BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Elemental magnetic vector charges linked to zero outward magnetic flux from any surface enclosing non-dipolar magnetic sources DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4851@events.saip.org.za DESCRIPTION:Speakers: Max Chirwa (Walter Sisulu University)\nA harmonious formulation of the inverse–square laws for fields shows that elemental s ources are rightfully represented as scalars for both gravitational and el ectric fields\, but as vectors for magnetic fields. This permits an effect ive simple illustration that\, unlike the gravitational or electric flux\, the magnetic flux out of any closed surface is zero irrespective of wheth er the enclosed magnetic source is dipolar or non-dipolar. Then Gauss’ l aws for gravitational\, electric and magnetic fields can be re-stated as: Out of any enclosing surface\, if the source is a scalar quantity then the net flux is equal to the source itself\; whereas if the enclosed source i s any vector quantity\, the net flux is the scalar zero.\n\nhttps://events .saip.org.za/event/7/contributions/4851/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4851/ END:VEVENT BEGIN:VEVENT SUMMARY:Ultrafast Transient Absorption measurements on Indoline D149 Dye DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4852@events.saip.org.za DESCRIPTION:Speakers: Egmont Rohwer (Stellenbosch University)\nD149 Dye ha s proven to be an effective photo-absorber for use in dye sensitized solar cells. Pump-probe measurements were conducted on D149 dye as well as D149 adsorbed to Zinc Oxide semi-conducting particles. Ultrafast dynamics on a sub-ps time scale\, easily resolved by the current experimental setup at the LRI\, were observed in both samples. Significant quenching of the exci ted state dynamics of the D149 molecule was seen in samples adsorbed to Zi nc oxide\, indicating the occurence of intermolecular charge transfer of p hoto-excited electrons from the singlet excited state of the D149 molecule and subsequent injection into the conduction band of the Zinc Oxide parti cles.\n\nhttps://events.saip.org.za/event/7/contributions/4852/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4852/ END:VEVENT BEGIN:VEVENT SUMMARY:The pair-model of monopolar and dipolar moments of elemental elect ric scalar and magnetic vector charges DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4857@events.saip.org.za DESCRIPTION:Speakers: Max Chirwa (Walter Sisulu University)\nA sequel to r epresenting elemental sources of magnetic fields as elemental magnetic vec tor charges is realizing that electric and magnetic dipole moments are dif ferent classes of moments. The distinction between monopolar and dipolar m oments becomes clearer when any distribution of electric scalar charge or magnetic vector charge is depicted as one or more pairs of charges with eq ual magnitudes. It is shown here that separation of the charges (electric scalar or magnetic vector) is essential for the very existence and other a ttributes of a dipole\, but not for a monopole. These representations are markedly different from the traditional analogous representations and noti ons of electric and magnetic dipole moments as sources of corresponding fi elds or potentials. It also emphasizes that fields and potentials are gene rated by the sources and not by their moments\; hence the difference betwe en these two entities.\n\nhttps://events.saip.org.za/event/7/contributions /4857/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4857/ END:VEVENT BEGIN:VEVENT SUMMARY:The effect of ventilation on the thermal performance of an energy efficient house DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4862@events.saip.org.za DESCRIPTION:Speakers: Thabiso Vincent Mthimunye (ufh)\nAn energy efficient passive solar house was designed\, constructed and its natural ventilatio n efficiency monitored. Carbon tracer test was used to measure the ventil ation efficiency of each ventilation component. Windows were found to have higher impact on the ventilation rate than doors. The correct operation o f the ventilation components was found to be the main contribution factor in natural ventilation.Tracer gas tests were conducted over a period of ti me to measure actual air change rates. Carbon dioxide was injected into th e house and its concentration monitored over time to determine how quickly the gas dissipates through the house’s envelope. The west side ventilat ion components were used to control the indoor environment by regulating t he amount of air flowing into the house. A carbon dioxide sensor was place d in the centre of the house at a height of about 0.45 m above the floor. A fan was used to pump the indoor air into the sensor at a rate of about 3 00 ml/min. To investigate the effects of each of the ventilation component configurations\, the ventilation rate tests were done in four configurati ons. A carbon dioxide sensor connected to a CR1000 data logger and a compu ter was used to monitor carbon dioxide concentration in the house. \nresul ts:The tracer gas technique was used to measure the air exchange rate. The average indoor and outdoor temperatures during these tests were\, Tin = 2 0 °C and Tout =17 °C\, and an average wind speed of 0.5 m/s blowing from W(600 150)N.when both windows and doors were opens. Results indicate that the concentration decays exponentially to the background concentration wi thin a period of 16 minutes. Assuming that the west window and door are th e only paths through which the westerly winds enter the house\, then the m ass air flow rate through the door and window is approximated.Take the ave rage air density to be 1.2 kg/m3\, an average indoor and outdoor pressure difference to be 4 Pa. For wide-open windows and doors\, the opening area is the sum of the windows and doors areas\, which gives 2.06 m2 and taking the discharge coefficient Cd=0.6 the average mass airflow was found to b e approximately 3.83 kg/s.Natural ventilation varies greatly on local fact ors such as wind speed and temperature which also influence at which occup ants open ventilation components.\n\nhttps://events.saip.org.za/event/7/co ntributions/4862/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4862/ END:VEVENT BEGIN:VEVENT SUMMARY:Generation of a Laguerre-Gaussian TEM01 mode in a monolithic micro chip laser DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4874@events.saip.org.za DESCRIPTION:Speakers: Darryl Naidoo (Council for Scientific and Industrial Research)\nWe explore a method in the selection of a specific higher-orde r mode through judicious shaping of the pump light to create a high modal overlap with the desired mode. To demonstrate this principle\, we create a donut-shaped pump profile in the focal plane of a converging lens by use of a beam shaping element. This pump profile is used to longitudinally pum p a monolithic microchip laser and a plano-concave resonator cavity where we achieve a TEM01 output with powers of ~12 mW and ~14 mW at slope effici encies of 17% and 21% respectively. In both cases the modal purity is high with a beam quality factor of ~2. Diffractive pump shaping of this form i s advantageous as it allows for high pump intensity even with low pumping powers\, thus ensuring sufficient gain is achieved for laser oscillation.\ n\nhttps://events.saip.org.za/event/7/contributions/4874/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4874/ END:VEVENT BEGIN:VEVENT SUMMARY:Analysis of aberrations generated in aerodynamic random media usin g computational fluid dynamics DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4878@events.saip.org.za DESCRIPTION:Speakers: Cosmas Mafusire (CSIR National Laser Centre)\nMedia generated by random mixing of hot and cold gases can be of great importanc e for laser beam propagation. However\, it is not always possible to repre sent the media’s behaviour using simple formulation. This opens the door for the use of numerical methods. We show that\, for aerodynamic media\, we can use computational fluid dynamics (CFD) software to acquire density distribution data to characterize both local and overall behaviour of the media. Using the Gladstone-Dale law\, we acquired refractive index distrib ution which we use to calculate Zernike coefficients from the respective l ocal phase values at various sections of the media. We show that once we h ave this data\, we can simulate the propagation of laser beams of various shapes in such media. We apply the method to analyse a spinning pipe gas l ens (SPGL) which is a horizontal pipe whose walls are heated rotated along its axis. We show that the results from the model agree with the SPGL exp erimental results.\n\nhttps://events.saip.org.za/event/7/contributions/487 8/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4878/ END:VEVENT BEGIN:VEVENT SUMMARY:Mathematical Modeling of a Concentrator-Diffuser Wind Energy syste m DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4880@events.saip.org.za DESCRIPTION:Speakers: Peace-Maker Masukume (University of Fort Hare\, Depa rtment of Physics)\n\nOptimization of power output from ducted wind turbin es has been the focus of many researchers in recent years. However many ha ve dwelt much on diffusers than concentrators (nozzles) . Diffusers are ch aracterized by flow separation due to deceleration of the fluid and this l eads to energy dissipation. On the other hand a concentrator is accompanie d by a favourable pressure gradient which stabilizes the boundary layer a nd thus minimizes energy dissipation. This study presents a mathematical m odel of a concentrator-Diffuser system which has been developed to optimiz e the power output of a low speed wind turbine. Optimization of the inclin ation angles of both the concentrator and the diffuser\, ducts exit ratios and the reduction in backpressure were found to augment the mass flow a t the rotor due to increased pressure drop and reduction in flow separatio n. It is illustrated that Power coefficients (Cp) of about 0.65 are achiev able.\n\nhttps://events.saip.org.za/event/7/contributions/4880/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4880/ END:VEVENT BEGIN:VEVENT SUMMARY:Batch anaerobic co-digestion of cow dung and donkey manure DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4883@events.saip.org.za DESCRIPTION:Speakers: Patrick Mukumba (University of Fort Hare)\nBiogas fr om anaerobic digestion can be a solution to current and future energy need s in South Africa. One option for improving biogas yield of anaerobic dige stion of organic matter is co-digestion. Cow dung and donkey manure were c o-digested together at different mixing ratios. Total Solids (TS) and vola tile solids (VS)\, ammonia-nitrogen\, pH\, alkalinity\, volatile fatty aci ds (VFA) and chemical oxygen demand (COD) were determined by using the sta ndard methods of the American Public Health Association (ALPHA). The press ure of the biogas was measured daily by means of a pressure gauge fixed on top on the batch biogas digester. Methane and carbon dioxide contents in the biogas were sensed by non-dispersive infra red sensors. Palladium/Nick el sensors were used for sensing hydrogen and hydrogen sulphide in biogas. Highest biogas yield was obtained for a mixing ratio of 50% cow dung to 5 0% donkey manure\, however lowest biogas yield was obtained from cow dung. For all the substrates the gas yield increased with time and then attains a constant value. However the co-digestion of cow dung and donkey manure attained maximum gas yield on 24th day while for cow dung it was on 28th d ay and for donkey manure it was on 26th day. Co-digestion of cow dung and donkey manure increased the gas yield by about 43%. Pure samples produced less biogas than co-digested samples. There was a strong positive relatio nship between gas production and % of co-substrates used (R2 = 0.999). The biogas produced from co-digestion can be a solution to lack of energy in rural areas in Eastern Cape Province of South Africa where plenty of donke ys and cattle are kept.\n\nhttps://events.saip.org.za/event/7/contribution s/4883/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4883/ END:VEVENT BEGIN:VEVENT SUMMARY:Ion irradiation effects on the formation of metal nanoparticles in crystals DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4898@events.saip.org.za DESCRIPTION:Speakers: Anna Kozakiewicz (Wits)\nMetal nanoparticles (MNP) w ere synthesized by room temperature ion implantation of high fluences (fro m 6x1016 to 5x1017 cm-2) of 150 keV Ag and 15 -22 MeV Au ions into Al2O3 a nd MgO single crystals.\nOptical absorption (OA) spectra show surface plas mon resonance (SPR) bands characteristic of the implanted metal ions. Upon annealing (300°-1200°C) the optical response of the metal nanostructure s changes\, related directly to their morphology\, shape and size. High re solution transmission electron micrographs indicate that the particles are often crystalline. The implanted ions profiles were obtained from 1.6 MeV He+ Rutherford Backscattering (RBS) for the silver implanted substrates a nd High Resolution Transmission Electron Microscopy (HRTEM)\, revealed bur ied layers of implanted ions.\n\nhttps://events.saip.org.za/event/7/contri butions/4898/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4898/ END:VEVENT BEGIN:VEVENT SUMMARY:Vanadium Dioxide Nanoplatelets Based nanocomposites for IR Solar R adiation Modulation DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4910@events.saip.org.za DESCRIPTION:Speakers: Aline SIMO (PHD Student)\nExamples of novel coating technologies towards Infrared solar radiation regulation/modulation in sma rt glass windows for the satellite sector include electrochromic and therm ochromic based high vacuum manufactured dynamic coatings. The latter two t echnologies are solar radiations control oriented technologies in the visi ble and infrared radiation respectively. The thermochromic smart coated wi ndows are infrared active and self regulating systems. Due to its natural phase transition around 68°C\, vanadium dioxide coated systems exhibit an exceptional reversible and self induced optical modulation in the infrare d solar spectrum. If the temperature of the vanadium dioxide coated on a g lass window is smaller than 68°C\, the smart window is transparent to the solar infrared radiations i.e. heat transmitting while it reflects the in frared radiations if its temperature is higher than 68°C i.e. heat opaque . To apply such a thermochromic smart material on a large scale in automot ive and building sector\, it is required to shift their transition tempera ture to about 25°C as well as innovating a physical-chemical process for production of large surface coatings. While the first requirement can be a chieved by tungsten doping\, the second could be reached by a hybrid polym er- VO2 (M) nanoparticles based coatings. This contribution reports the ph ysical and specifically the optical characteristics of VO2 nanoplatelets/P VP nano-composites.\n\nhttps://events.saip.org.za/event/7/contributions/49 10/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4910/ END:VEVENT BEGIN:VEVENT SUMMARY:A Diagnostic 'tool' to prevent the consequences of material failur e DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4912@events.saip.org.za DESCRIPTION:Speakers: Ike Sikakana (Vaal University of Technology)\nIn mat erials’ manufacturing\, evaluation and/or characterization is a key fina l stage in the production process. This quality assurance tests whether t he product meets an industry norm or specified standard required by the cu stomer.\nThe evaluation is also required on machinery / plant parts that a re already in operation. The parts are periodically ‘tested’ to ascer tain as to whether they can still function safely and as originally design ed.\nThe evaluation\, characterization\, testing is conducted using techni ques that do not damage these parts / materials. This novel way of materia ls’ examination\; referred to as Non-Destructive Testing / Evaluation (N DT/E)\; is finding increasing applications is numerous industries.\nThis p aper focuses\, first\, on the use of NDT/E in selected industries and its critical nature in the safe operation of plant machinery and structures.\n Secondly\, an overview of the education and training required in NDT/E is discussed. The qualification offered at the Vaal University of Technology (VUT) and its impact on the NDT/E profession in South Africa is reflected upon.\nThirdly\, the rewards of an NDT/E career are discussed. This is c ontrasted with the perceived low profile of NDT/E amongst practicing engin eers in South Africa.\nLastly\, an argument for the urgent need of a legis lative framework for the regulation and recognition of NDT/E qualification s and certification in South Africa is advanced. It is emphasized that thi s is a necessary measure to have accountability and a code of ethics entre nched in this growing profession.\n\nhttps://events.saip.org.za/event/7/co ntributions/4912/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4912/ END:VEVENT BEGIN:VEVENT SUMMARY:Influence of solvent effects on Qy transitions in chlorophyll DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4915@events.saip.org.za DESCRIPTION:Speakers: Jacoba Smit (CSIR Biosciences\, Pretoria\, South Afr ica)\nThe most abundant and efficient light harvesting\, energy transfer a nd transduction systems are found in nature within the process of photosyn thesis. Although the processing sequences of an absorbed solar photon in t he photosynthetic apparatus have been deciphered\, the underlying physical basis of photosynthesis is not well understood yet. Our research aims to contribute to this understanding by characterising the level of organisati on of the Light Harvesting II complexes (LHCII) and energy transfer system s when incorporated into artificial vesicles called PheroidTM. LHCII was e xtracted from spinach leaves in a 20 mM Tricine buffer to stabilise the pr oteins. Raman\, FTIR and absorbance spectra of samples were compared. The Qy transitions of chlorophyll in the red (Qy) region of the absorption spe ctra appears to red-shift by 3.5 – 5.5 nm\; indicating a possible change in organisation of the light harvesting system after incorporation into t he PheroidTM. These shifts however could also be interpreted as bathochrom ic solvent effects due to the Tricine buffer. The objectives of this study were (1) to investigate whether the red-shifts were due to the Tricine bu ffer and (2) if so\, whether the alternative use of a 20 mM K2HPO4 / KH2PO 4 buffer could eliminate the bathochromic solvent effects. The Tricine buf fer was dialysed out of the samples directly into a 20 mM K2HPO4 / KH2PO4 buffer to prevent denaturing of the LHCII proteins. Preliminary results in dicated a lessening of the bathochromic effects with the K2HPO4 / KH2PO4 b uffer.\n\nhttps://events.saip.org.za/event/7/contributions/4915/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4915/ END:VEVENT BEGIN:VEVENT SUMMARY:Testing the Cosmic Ray-Lightning Connection Hypothesis DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4936@events.saip.org.za DESCRIPTION:Speakers: Andrew Collier (University of KwaZulu-Natal)\nThe pr oposed dependence of atmospheric electrical properties on the ionizing inf luence of cosmic rays has resulted in numerous attempts to obtain convinci ng correlations. While most of the studies remain largely theoretical\, a few results (e.g. Stozhkov\, 2003) indicate that there is a plausible link between lightning activity and the cosmic ray ionization rate measured at specific locations on Earth. The present work uses data from the World Wi de Lightning Location Network (WWLLN) to investigate the impact of cosmic rays on lightning on a global scale. The availability of global lightning data from WWLLN\, and assimilated cosmic ray data from a global network of neutron monitors provides a good opportunity to study the relationship be tween cosmic ray variations and lightning occurrence on a larger spatial s cale than was previously possible.\n\nhttps://events.saip.org.za/event/7/c ontributions/4936/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4936/ END:VEVENT BEGIN:VEVENT SUMMARY:Atmospheric turbidity over Gauteng DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4938@events.saip.org.za DESCRIPTION:Speakers: Thabang Sethabane (Dept. Physics\, University of Joh annesburg)\nWe have analysed broad-band global solar irradiation measureme nts collected at the Soweto campus of the University of Johannesburg over the two-year period 1998-1999. We estimate the direct and diffuse irradiat ion using radiation models\, and utilise the results to determine the atmo spheric turbidity for all cloud-free days. From this we calculate aerosol densities and the solar radiation potential for the location. We further evaluate the applicability of several irradiation models\, incorporating m olecular absorption\, Rayleigh and Mie scattering\, to this part of Gauten g.\n\nhttps://events.saip.org.za/event/7/contributions/4938/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4938/ END:VEVENT BEGIN:VEVENT SUMMARY:Towards Scientific Establishment and Validation of Quality Standar ds for Digital Thermal Neutron Imaging DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4939@events.saip.org.za DESCRIPTION:Speakers: Mabuti Jacob Radebe Radebe (Necsa)\nDigital thermal neutron imaging (radiography and tomography) is a powerful non-destructive analytical tool and has demonstrated its importance in industrial and res earch application world-wide. However\, standards through test samples\, methods and procedures\, which are essential when the technique is to be a pplied in the national and international industrial and research environme nt\, do not exist yet. Firstly\, characterization of the hardware faciliti es is essential in order to determine their capabilities in terms of beam properties\, detection properties and subsequent combinations of the two s uch as spatial and temporal resolution\, acquisition period\, L/D\, S/N ra tio\, etc. This can be achieved through the implementation of test sample s and test methods which entails the efforts towards achieving the correct test specimens\, procedures and practices. \nSecondly\, obtaining accurat e quantitative information from digital thermal neutron images is an impor tant development of this decade\, and establishment and finalization of st andardization in this regard is essential. A properly validated methodolog y to standardize quantitative digital thermal neutron imaging is of import ance in a number of current research fields of global interest which inclu des in-situ investigations of fuel cell dynamics as well as quantification in porous media. This presentation provides the layout of the proposal fo r the PhD study intended at contributing towards the establishment of nati onal and international standards for digital thermal neutron imaging. This entails a contribution towards the establishment\, evaluation\, validatio n and improvement of special test specimens as well as the creation and re finement of measurements\, procedures and practice utilizing digital neutr on radiographs and tomograms.\n\nhttps://events.saip.org.za/event/7/contri butions/4939/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4939/ END:VEVENT BEGIN:VEVENT SUMMARY:The extent of the chorus observed at Marion Island DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4942@events.saip.org.za DESCRIPTION:Speakers: Andrew Collier (Hermanus Magnetic Observatory)\nOn t he 4 August 2010\, chorus was observed at Marion Island from 03:00 - 07:00 UT (06:00 - 10:00 LT). Marion Island (46.9°S/37.1°E\, L = 2.62) is with in the plasmasphere during periods of low geomagnetic disturbance\, making the observation of chorus there a rare occurrence. On the 4 August\, a mo derate geomagnetic storm occurred\, with a maximum Kp of 6+\, and a minumu m DST of -70nT. These conditions compressed the plasmasphere to such an ex tent that Marion Island was near to\, or outside\, the plasmaspause at the time of the emission\, making the observation of chorus possible. On the same day\, there chorus was also observed at SANAE IV (L = 4.32). The spec tral properties of these chorus are different\, meaning that the chorus ob served at SANAE IV was generated in a different region to that observed at Marion Island. We present broadband data from both Marion Island and SANA E IV\, and extent of the chorus generating region is inferred from DEMETE R data.\n\nhttps://events.saip.org.za/event/7/contributions/4942/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4942/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational study of some Carbon modification DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4944@events.saip.org.za DESCRIPTION:Speakers: MOSHIBUDI SHAI (UNIVERSITY OF LIMPOPO)\nClassical mo lecular dynamics simulations were used to study the modification of some c arbon forms. The type of carbons that were used is diamond and nanocarbon. Carbon is unique among other elements in its ability to form strong chemi cal bonds with a variety of coordination numbers. The simulations predict that the behaviour of diamond and nanocarbon are similar although the nano tube has low minimum energy compared to the bulk diamond. The radial distr ibution functions of the two forms differ by half a magnitude.\n\nhttps:// events.saip.org.za/event/7/contributions/4944/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4944/ END:VEVENT BEGIN:VEVENT SUMMARY:The Effects Of High Atomic Material On Photon Beams At The Interfa ce DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4953@events.saip.org.za DESCRIPTION:Speakers: Enoch Sithole (University of Limpopo)\nThe purpose o f this work was to study the dose enhancement factor (DEF) by high-Z mater ial in water phantom\, irradiated by photon beams. Two energies\, 6 and 15 MeV generated by Varian linear accelerator were used. Monte Carlo techniq ue (EGSnrc code) was used in this study. The source model was validated ag ainst measured data. The effect of photon beam quality\, atomic number (Z) and the material thickness in the water phantom were studied. Calculation s for a variety of materials and photon beams showed that dose enhancement factor increase with Z\; decrease with decreasing material thickness\; an d decrease with decreasing incident photon beam energy.\n\nhttps://events. saip.org.za/event/7/contributions/4953/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4953/ END:VEVENT BEGIN:VEVENT SUMMARY:Polarization Encoded QKD in Fibre DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4960@events.saip.org.za DESCRIPTION:Speakers: Sharmini Pillay (University of KwaZulu-Natal)\nQuant um Key Distribution employs the laws of quantum mechanics for the purpose of cryptography. Two parties\, called Alice and Bob\, are able to create a random key which is used to encrypt a message. QKD is a provably secure m ethod for cryptography because any eavesdropper attempting to anonymously retrieve the key must make measurements\, thereby disturbing the system. U sing this principle\, a high error rate between the two authenticated part ies indicates a compromise in the system and the process by which the key is shared is aborted.\nThe quantum channel can be implemented using a free -space link between Alice and Bob\, but in many instances\, this is not pr actical for implementations. Fibre optic cables provide an alternative wit h current technology. In order to implement protocols such as the BB84 pro tocol\, the state of polarization of photons must be maintained between Al ice and Bob. This is because the BB84 protocol utilizes the states of pola rization of photons as qubits (quantum bits). However\, the polarization o f light is altered when passed through a fibre. This is due to impurities in the fibre\, manufacturing errors or environmental stresses such as heat ing or movement. This causes refractive differences between polarized stat es which change the state of polarization. This property is called birefri ngence.\nPolarization mode dispersion allows for the state of polarization to be corrected when a photon is transmitted through fibre. If the fibre is fixed\, the environmental stresses result in a unique and constant chan ge of polarization [4]. This can be compensated for by rotating each photo n appropriately before being measured and each length of fibre will requir e its own unique adjustment. If the fibre is subjected to variable conditi ons\, changes in the state of polarization of photons must be monitored an d adjustments must be made at suitable time intervals. Using this method\, polarization encoded QKD can be implemented in fibre.\n\nhttps://events.s aip.org.za/event/7/contributions/4960/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4960/ END:VEVENT BEGIN:VEVENT SUMMARY:Evaluation of WC-9Co-4Cr laser surface alloyed coatings on stainle ss steel DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4985@events.saip.org.za DESCRIPTION:Speakers: BABATUNDE OBADELE (TSHWANE UNIVERSITY OF TECHNOLOGY) \nIn order to examine the effect of Cr on the microstructure and hardness behaviour of WC cermet\, coatings have been obtained by laser surface allo ying technique. WC-9Co-4Cr particulate was injected into the surface of AI SI 304L stainless steel under different processing variables. The morpholo gies and microstructures of the composite coatings were investigated using optical microscopy and high resolution scanning electron microscopy\, whi le the phase changed were observed using x-ray diffraction. The surface ha rdness was determined using the Vickers microhardness tester. The excessiv e heat from the laser beam partially melt the WC-Co which results in carbo n deficiency and precipitation of carbon as graphite to form CO2 pores wi thin the coatings. 4% Cr has been added to compensate for the precipitatio n of graphite to form Cr3C2. A considerable increase in hardness value fro m 246 to 1331 Hv0.1 was achieved when alloying was carried out at high las er power and speed\, the pores being completely eliminated.\n\nhttps://eve nts.saip.org.za/event/7/contributions/4985/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4985/ END:VEVENT BEGIN:VEVENT SUMMARY:Clay/sawdust porous pots for water treatment DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4980@events.saip.org.za DESCRIPTION:Speakers: Joseph A Varkey (University of Swaziland)\nThe suppl y of adequate clean water to communities is a problem in many countries\, especially in Africa where the rural population depend on water from river s\, dams and streams for domestic use. Such water contains many chemical s ubstances and microorganisms that affect the health of human beings and an imals. Use of simple water purification systems\, like filters\, by househ olds\, is a possible solution to this problem. In our laboratory\, we hav e developed a porous pot water filter using sawdust and clay. Both materi als are available locally. Sawdust was sieved using 100\, 250 and 600 micr ometer sieve and then mixed with clay in the clay/ sawdust ratio of 1:3 by volume. The mixture was then used to make pots\, which were porous. These pots were tested for their capacity to purify contaminated water collecte d from rivers. The filtration rate\, as a function of the clay/coal ratio\ , was also measured. Subsequently\, quality tests were done on the filtere d water and raw water to determine the potability of the filtered water. T he tests included microbiological\, physical and chemical properties. The results were then compared with standards provided by World Health Organiz ation.\n\nhttps://events.saip.org.za/event/7/contributions/4980/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4980/ END:VEVENT BEGIN:VEVENT SUMMARY:Schottky contact on GaN DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-4990@events.saip.org.za DESCRIPTION:Speakers: Mmantsae Diale (University of Pretoria)\nMetal Au\, Ni and Ni/Au contacts on n-GaN were studied for metal contacts for the fab rication of Shottky barrier ultraviolet photodetectors. AES\, RBS and curr ent-voltage measurements were used to study the samples. Figure 2 shows th e current voltage mechanism of Au\, Ni and Ni/Au transparent contacts onto GaN. The Schottky barrier heights of Au contacts were averaged at 0.84 ± 0.02 eV and the ideality factors of 1.7 ± 0.3. Series resistance for the se contacts was about 481 ± 4 Ω. Ni contacts onto GaN are dominated by t unneling currents and the leakage current is higher than that of Au. The S chottky barrier heights of Ni contacts were averaged at 0.82 ± 0.04 eV an d the ideality factors of 1.9 ± 0.2. Series resistance for these contacts was about 38 ± 1 Ω\, far less than that of Au contacts. Ni/Au contacts are annealed at 500 °C for transparency. The leakage current of Ni/Au is two orders of magnitude lower than that of Ni and Au\, and the Schottky ba rrier height was averaged at 2.04 ± 0.01 eV for ideality factors of about 1.6 ± 0.4.\n\nhttps://events.saip.org.za/event/7/contributions/4990/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/4990/ END:VEVENT BEGIN:VEVENT SUMMARY:Ionospheric response during the geomagnetic storm events on 24-27 July 2004: Long-duration positive storm effect DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5003@events.saip.org.za DESCRIPTION:Speakers: Chigomezyo Ngwira (Rhodes University/SANSA Space Sci ence)\nIonospheric storms represent large global disturbances in the ionos pheric F2 region electron density in response to geomagnetic storms. The m echanisms for generation of negative storms are well understood and accept ed. In contrast\, positive storms show different characteristics and have not been fully understood. In this study\, we investigate the ionospheric response during the geomagnetic storm events on 24-27 July 2004 using a mu lti-instrument approach. The period was characterised by strong geomagneti c activity that produced a positive ionospheric total electron content (TE C) effect over a four day period\, but the most significant enhancements ( with respect to the quiet day reference) were observed on 25 and 27 July a nd are presented here. It is noted that the enhancement on 25 July (40 TEC U) was about twice as high as that observed on 27 July\, even-though the l ater day was more geomagnetically disturbed. The positive storm enhancemen t on 25 July lasted over 9 hours and that on 27 July lasted about 7 hours\ , thus can both be classified as long-duration positive storm effects. Als o\, IMF Bz had a southward orientation for more than 15 hours on 25 July a nd could have been the mean by which energy was continuous fed into the ma gnetosphere. The DMSP F15 satellite which flew over the region of positive storm also observed the enhancement. In addition\, the F-region critical frequency (foF2) values observed at two ionosonde stations showed marked p ositive responses and were associated with increase in ionospheric height. \n\nhttps://events.saip.org.za/event/7/contributions/5003/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5003/ END:VEVENT BEGIN:VEVENT SUMMARY:Performance monitoring of a downdraft System Johansson Biomass Gas ifier™ DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5004@events.saip.org.za DESCRIPTION:Speakers: Sampson Mamphweli (University of Fort Hare)\nBiomass gasification for electricity generation has attracted much attention over the past few years. This is due to the fact that biomass is a renewable r esource\, which is also considered to be carbon neutral. However electrici ty generation using biomass gasifiers can only be technically and economic ally achieved at small scale using downdraft gasifier systems\, which prod uce gas that has very little quantities of tar. This paper presents the te chnical and operational challenges experienced in biomass gasification for electricity generation. The data was collected at the System Johansson Bi omass Gasifier installed by Eskom. NDIR and Pd/Ni gas sensors were used to measure the gas profiles while type K thermocouples were used to measure the temperature in the reactor. This paper presents the performance monito ring results including the gasifier operating conditions\, fuel properties \, gas profiles as well as gas heating value and cold gas efficiency.\n\nh ttps://events.saip.org.za/event/7/contributions/5004/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5004/ END:VEVENT BEGIN:VEVENT SUMMARY:An investigation of high velocity flows in HF radar data during no rthward interplanetary magnetic field\, non-substorm intervals DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5006@events.saip.org.za DESCRIPTION:Speakers: Zolile Mtumela (University of KwaZulu-Natal)\nSevera l previous studies\, including one using early Sanae radar data\, have fou nd examples of high speed ionospheric plasma flows on the nightside\, mapp ing to the magnetospheric tail\, during periods which were magnetically qu iet. These high speed flows were interpreted to be associated with the rel ease of energy from a rapid reconfiguration of tail magnetic field lines d ue to reconnection. Such events are now known as ‘TRINNIs’ or ‘tail reconnection during IMF northward\, non-substorm intervals’. The purpose of this study was to identify further TRINNI events\, using SuperDARN dat a from both hemispheres. In situations where the y-component of the Interp lanetary Magnetic Field dominates over the z-component\, the directions of both the high speed flows and the underlying convection pattern depend on the direction of the y-component. Some examples of likely TRINNI events f or cases where the y-component was positive and negative are presented and discussed. The assumption of a non-substorm interval is justified by magn etometer and GOES satellite data\, and the observations are discussed in r elation to magnetic reconnection in the magnetotail.\n\nhttps://events.sai p.org.za/event/7/contributions/5006/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5006/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigating the effect of atmospheric dymanics on HF propagation DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5010@events.saip.org.za DESCRIPTION:Speakers: Racheal Athieno (South African National Space Agency (SANSA) Space Science)\nHF propagation involves transmission and receptio n of radio signals within a frequency range of 3 − 30 MHz. It finds appl ications in a number of communication fields such as international short w ave broadcasting\, mobile telephone systems\, radio navigation and operati on of radar systems. However\, it depends on the ionosphere which is cons tantly varying mainly due changes in the neutral atmosphere which are a co nsequence of atmospheric dynamics. In this paper\, we investigate the effe ct of atmospheric dynamics on High Frequency (HF) propagation using the co -located radars at SANSA Space Science (19.2o E\, 34.4o S)\, Hermanus\, So uth Africa. These radars include the HF Doppler radar\, Ionosonde\, Globa l Positioning System (GPS) receiver and GPS Ionospheric Scintillation Tota l Electron Content (TEC) Monitor (GISTM). HF propagation results from the HF Doppler radar are presented. The comparison of results of the HF Dopp ler radar with other radars is also included. Results show that radio comm unication is affected by atmospheric dynamics which results into signal fa ding or at worst signal loss.\n\nhttps://events.saip.org.za/event/7/contri butions/5010/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5010/ END:VEVENT BEGIN:VEVENT SUMMARY:Simulation of a pencil proton beam in a water phantom using variou s monte carlo codes. DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5011@events.saip.org.za DESCRIPTION:Speakers: Carmen Jacobs (University of the Western Cape)\n\nTh is study investigates the Pencil Proton Beam scanning technique to determi ne the dosage obtained during clinical treatments due to secondary radiati on. Simulations in MCNPX and GEANT4/GATE are of particular interest in thi s study. The study is based on a variation of the traditional Hogstrom Pen cil beam model for electron beams to provide a description of clinical pro ton beams. This new Hogstrom model is based on the Fermi-Eyges theory of p article transport.\n \nThe method used in this investigation is to simulat e a proton pencil beam entering a water phantom at various discrete energi es and determining the secondary particles distributed throughout the wate r phantom by studying both Coulombic and Nuclear interactions of the incid ent proton in water. This allows one to determine how much of the total do sage obtained by the patient is from the primary particle and what part of the dosage is due to the secondary particles. In order to accurately comp are the Monte Carlo codes\, a further study was done to understand the und erlying physics principles used by MCNPX and GEANT4. The development of an analytical model for primary proton beams which included depth distributi on\, propagations of protons in matter\, and scattering theory was also in vestigated. \n\nBesides comparing Monte Carlo codes this study also has re al life implications. Pencil beam scanning leads to improving and advancin g treatment planning.\n\nhttps://events.saip.org.za/event/7/contributions/ 5011/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5011/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of carbon modification on the electrical\, structural and o ptical properties of TiO2 electrodes and their performance in lab-scale dy e sensitized solar cells DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5020@events.saip.org.za DESCRIPTION:Speakers: Raymond Taziwa (University of Fort hare)\nCarbon mod ified titanium dioxide nanoparticles (C:TiO2 NPs) have been synthesized by ultrasonic nebulizer spray pyrolysis (USP) and pneumatic spray pyrolysis (PSP) techniques using titanium tetraethoxide as the precursor solution. H igh resolution transmission electron microscopy on the NPs shows differenc e in lattice spacing in the NP structures prepared by the two methods – 2.02 Å for the USP NPs and an average of 3.74 Å for the PSP NPs. The mos t probable particle sizes are 3.11 nm and 5.5 nm respectively. The carbon doping only changes the lattice spacings of the TiO2 lattice\; the most pr edominant plane is the (101) in TiO2 reciprocal lattice as determined from the fast Fourier transform of most of the particle images. Raman spectros copy supported by FTIR confirms the TiO2 polymorph to be anatase with the intense phonon frequency at 153 cm-1 blue-shifted from 141 cm-1 due to bot h carbon doping and particle size. A modified phonon confinement model fo r nanoparticles has been used to extract phonon dispersion and other param eters for anatase for the first time. Electronic measurements show “nega tive conductance” at some critical bias voltage\, which is characteristi c of n-type conductivity in the carbon doped TiO2 NPs as confirmed by the calculated areas under the I-V curves. This is a necessary material proper ty for the Grätzel type of solar cells application. Practical solar cells built from carbon doped TiO2 electrodes show up to 5 times improvement in efficiency compared to pure TiO2 electrodes of similar construction.\n\nh ttps://events.saip.org.za/event/7/contributions/5020/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5020/ END:VEVENT BEGIN:VEVENT SUMMARY:Trajectories of electrons in a realistic model of the Earth's magn etic field DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5021@events.saip.org.za DESCRIPTION:Speakers: Mahassin Nemair (University of KawZulu-Natal)\nDurin g the onset of a substorm\, a burst of energetic (10-100 keV) electrons is injected into the inner\nmagnetosphere. The subsequent motion of these el ectrons is dictated by their energy\, pitch angle\nand the Earth's magneti c field geometry. More specifically\, if the Earth's magnetic field is not \nvarying rapidly then the three adiabatic invariants associated with each of the electrons' periodic\nmotions (drift\, bounce and gyration) are con served. In this work we study the motion of electrons in\nthe Earth's magn etic field. A realistic magnetic field geometry is employed which depends on\nconditions in the solar wind by applying time varying magnetic filed c alculated from Tsyganenko\nmodel. The initial electron source location is presumed to be at L = 9 at midnight. The trajectories\nof electrons with e nergies of 10-100 KeV are studied using Tsyganenko model of the\nmagnetosp here. Results are compared with other model simulated .\n\nhttps://events. saip.org.za/event/7/contributions/5021/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5021/ END:VEVENT BEGIN:VEVENT SUMMARY:Stellar Masses of Star Forming Galaxies in Galaxy Cluster DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5030@events.saip.org.za DESCRIPTION:Speakers: Solohery Randriamampandry (SAAO/UWC)\nWe determine t he stellar mass of star forming galaxies in the X-ray luminous cluster MS 0451.6-0305 at z ∼ 0.54. The stellar masses are estimated from fitting m odel spectral energy distributions (SEDs) to deep\, optical UBRIz observat ions obtained from WIYN 3.5m telescope and public NIR K-band image from Pa lomar Observatory telescope. The model SEDs are based on the stellar popul ation synthesis (SPS) model of Bruzual & Charlot (2003) and Conroy et al. (2009) that span a wide range of age\, star formation history\, initial ma ss function\, metallicity and dust content. We measure stellar masses for galaxies down to M* ∼ 2x108Mʘ. We find a tight correlation between stel lar masses derived from the two SPSs. We compare the derived stellar masse s to the dynamical masses for a set of 25 star-forming galaxies. The dynam ical masses are derived from high resolution\, spectroscopic observations of emission lines from the DEIMOS spectrograph on the Keck telescope. A st rong correlation is seen between the dynamical and stellar mass for the ga laxies\; and the star forming galaxies show fairly constant ratio between stellar and dynamical mass. When comparing to the field sample of Guzmán et al. (2003) of luminous compact blue galaxies\, we see an excess of low mass galaxies in the cluster.\n\nhttps://events.saip.org.za/event/7/contri butions/5030/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5030/ END:VEVENT BEGIN:VEVENT SUMMARY:Femtosecond amplifier pulse characterization: FROG and shaper-assi sted techniques DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5038@events.saip.org.za DESCRIPTION:Speakers: Attie Hendriks (SAIP member)\nWe present pulse chara cterization of various amplified shaped pulses\, using second harmonic aut ocorrelation\, frequency resolved optical gating (FROG)\, as well as their analogue techniques using only the pulse shaper and no moving parts in th e experimental setup. This involves creating double pulse seperations usin g the pulse shaper only and recording the resulting SHG autocorrelation an d FROG signals. Pulse shaper assisted characterization is presented in det ail for our setup which includes an acousto-optic programmable dispersive filter (Dazzler) coupled with a Matlab program incorporating pulse energy stabilization to compensate for shaper efficiency changes.\n\nhttps://even ts.saip.org.za/event/7/contributions/5038/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5038/ END:VEVENT BEGIN:VEVENT SUMMARY:Efficiency Dependence of Tm3+ -Doped Silica Triple-Clad Fiber Lase r DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5042@events.saip.org.za DESCRIPTION:Speakers: Wilfrid Ndebeka (MSc Student)\nWe present measuremen ts of the slope efficiency of a Tm3+ -doped silica triple-clad fiber laser emitting at 2.02 µm using different cooling techniques. The maximum slop e efficiency of 53.6 % was obtained at a temperature of 25o C with a maxim um output power of 5 W for 19 W of absorbed power at the pump wavelength o f 800 nm and 9.9 W threshold. In a slightly different setup\, the output p ower could be increased to 10 W for an absorbed pump power of 32 W.\n\nhtt ps://events.saip.org.za/event/7/contributions/5042/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5042/ END:VEVENT BEGIN:VEVENT SUMMARY:An automated temperature control model for a well-mixed biomass re actor DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5044@events.saip.org.za DESCRIPTION:Speakers: FELIX PAGONA (PHYSICS DEPARTMENT\, UNIVERSITY OF FOR T HARE)\nA mathematical model for temperature control in a continuously st irred tank reactor is developed. The startegy used involves a coil immerse d in a coolant which proves to provide sufficient heat removal by contro lling the coolant flow rate in exponential mode. The approach shows that s pecific ranges of exponents for the coolant flow rate must be used for the reactor to operate optimally.\n\nhttps://events.saip.org.za/event/7/contr ibutions/5044/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5044/ END:VEVENT BEGIN:VEVENT SUMMARY:Metal-Semiconductor Ohmic Contacts: An ab initio Density Functiona l Theory Study of the Structural and Electronic Properties of Metal-Diamon d (111)-(1x1) Interfaces. DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5058@events.saip.org.za DESCRIPTION:Speakers: Isaac Motochi (PhD student\, University of the Witwa tersrand)\nMetal contacts on clean\, hydrogenated and oxygenated diamond s urfaces have been studied using ab initio Density Functional Theory. Five metals\, i.e.\, gold\, titanium\, tantalum\, vanadium and palladium on the three surfaces were considered. Gold and palladium were found to form wea k bonds on clean\, hydrogenated or oxygenated diamond (111) surfaces compa red to the other three metals. Bulk properties were also studied following the formation of the respective ohmic contacts on the three surfaces. The clean diamond surface was found to have surface states which were modifie d by oxygen but removed by hydrogen. Density of states studies revealed th at all the investigated metals had an effect on the electrical properties of the diamond surface. A peak that is characteristic of diamond was obser ved at ≈ -11.8 eV. For the clean diamond surface terminated with gold an d palladium\, states due to Au-2p orbitals were observed at ≈ -2.5 eV an d ≈ -1.5 eV\, while Pd-5s orbitals were located at ≈ -1.7 eV and ≈ - 0.5 eV on the same surface. Titanium\, tantalum and vanadium showed unique states at high binding energies of ≈ -38 eV for vanadium\, ≈ -34 eV f or tantalum and ≈ -32.5 eV for titanium\, which were thought to be respo nsible for their strong bonding.\nKey words: Metal-diamond interface\, Ads orption\, ohmic contacts\n\nhttps://events.saip.org.za/event/7/contributio ns/5058/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5058/ END:VEVENT BEGIN:VEVENT SUMMARY:A Magnetic Field Study Using Polarized Dust Emission of Nearby Sta rburst Galaxies DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5070@events.saip.org.za DESCRIPTION:Speakers: Lerothodi Leeuw (University of Johannesburg)\nWe wil l present submillimeter (submm) polarized imaging of the nearby star-formi ng galaxies M82 and NGC253. The data\, obtained with the Caltech Submillim eter Observatory in Hawaii\, probe the emission from dust grains aligned b y magnetic fields in these galaxies\, and thus fields in relatively dense regions of the galaxies.\n\nhttps://events.saip.org.za/event/7/contributio ns/5070/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5070/ END:VEVENT BEGIN:VEVENT SUMMARY:Spectral response as a diagnostic tool for PV and PC solar cells DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5072@events.saip.org.za DESCRIPTION:Speakers: Maibi Malape (Fort Hare Institute of Technology)\nTh e spectral response measurement system is an important tool for optimizati on of solar cells. Its measurement permit an examination of how photons of different wavelength contribute to the cell generated current at zero bia s voltage. In this study photovoltaic (PV) and photochemical (PC) solar ce lls were used and their spectral responses were measured. The aim is to us e the spectral response data in order to investigate the effect of shading on PV and PC solar cells. Preliminary results showed that the shading of cells degrade cells responsivity.\n\nhttps://events.saip.org.za/event/7/co ntributions/5072/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5072/ END:VEVENT BEGIN:VEVENT SUMMARY:Daytime modeling of VLF radio waves over land and sea\, comparison to DEMETER satellite data. DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5085@events.saip.org.za DESCRIPTION:Speakers: Andrew Collier (Hermanus Magnetic Observatory)\nVery Low Frequency (VLF) radio waves travel with little attenuation in the Ear th-ionosphere waveguide. The waveguide propagation conditions are determi ned by a variety of factors including the surface of the Earth and the fre e electron density profile. Perturbations of the lower ionosphere modify the waveguide and the propagation conditions in it. A model based on Wait 's mode theory is developed and used to investigate the propagation of VLF radio waves under different conditions. As the VLF radio waves reflect o ff the lower ionosphere\, a portion of the energy leaks up into space\, le aving a 'fingerprint' of the modal interference pattern of the waveguide m odes. This idea is used to test the validity of the model by comparing si mulation results with satellite data from DEMETER taken over the NWC trans mitter in North-West Australia.\n\nhttps://events.saip.org.za/event/7/cont ributions/5085/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5085/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for the Standard Model Higgs boson to WW with a hadronic ta u channel DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5122@events.saip.org.za DESCRIPTION:Speakers: Simon Connell (University of Johannesburg)\nIn the l arge mass region\, the dominant decay mode of the Higgs boson is to two W bosons\, where the Higgs can be produced via either gluon fusion or vector boson fusion. Of the possible W decay modes\, the current analyses focus on the W(->l nu)W(->l nu) decay channels where the lepton is either an ele ctron or muon. At a center of mass energy of 7 TeV\, the results from the ATLAS detector are combined for each of the three modes ee\, e mu\, or mu mu\, in order to maximise the signal sensitivity. We investigate the possi ble sensitivity gained in including a single hadronic tau channel (W->tau nu->(tau_had nu) nu) in this analysis\, and discuss the method in comparis on to the standard H->WW->l nu l nu search. Our work currently focuses on the hadronic tau identification and understanding the jet -> tau fake rate .\n\nhttps://events.saip.org.za/event/7/contributions/5122/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5122/ END:VEVENT BEGIN:VEVENT SUMMARY:Development of a laser cooling and magneto-optical trapping experi ment for Rubidium 87 atoms DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5086@events.saip.org.za DESCRIPTION:Speakers: Charles Rigby (Laser Research Institute\, Stellenbos ch University)\nA magneto optical trap (MOT) is capable of trapping a vapo r cloud consisting of atoms cooled down to the micro Kelvin range. Three o rthogonal pairs of counter-propagating laser beams of the correct circular polarisation form an optical molasses which facilitates the cooling of ne utral atoms. Additionally a spatially non-uniform\nmagnetic field produced by two current carrying coils in a Maxwell gradient configuration is used to trap the cooled atoms.\n\nIn this poster the effects of the trap param eters\, including the laser beam intensity and frequency detuning\, beam d iameter and magnetic field gradient\, on the number of trapped atoms are d iscussed. The nature of the beam polarisation and its importance in the co ntext of the experiment is measured and discussed.\n\nThe current status o f our development of an experimental setup for laser cooling and trapping of 87Rb atoms in vacuum with the aid of a MOT is presented.\n\nhttps://eve nts.saip.org.za/event/7/contributions/5086/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5086/ END:VEVENT BEGIN:VEVENT SUMMARY:Ultraluminous X-ray Sources in Nearby Galaxies DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5130@events.saip.org.za DESCRIPTION:Speakers: Deatrick Foster (South African Astronomical Observat ory)\nFor many Galactic black hole binaries\, there exists kinematic data that constrain the black hole masses to be within the stellar-mass regime. However\, due to their extragalactic distances\, ultraluminous X-ray sour ces (ULXs) have no such available dynamical information. Hence\, in order to constrain the system parameters\, we must use indirect methods. We pres ent an analysis of recent observations which suggest that\, rather than be ing powered by intermediate-mass black holes\, ULXs may represent an extre me form of "conventional" stellar-mass black holes.\n\nhttps://events.saip .org.za/event/7/contributions/5130/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5130/ END:VEVENT BEGIN:VEVENT SUMMARY:Direct water cooling effect on a photovoltaic module DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5107@events.saip.org.za DESCRIPTION:Speakers: Busiso Mtunzi (Fort Hare Institute of Technology\, U niversity of Fort Hare\, Physics Department)\nThis paper gives the details of a photovoltaic water heating system and the effects of direct water co oling on the performance of a photovoltaic module. The SW 80 polcrystallin e modules were used in the investigation. They wehre both fixed next toe a ch other on a north facing rack located on roof top. One of the modules h ad a batch water cooling container and the other module had no cooling sys tem attached to it. The water cooled module wer noted to operate at an ave rage temperature of 43°C on a sunny cloudless day\, while the uncooled mo dule's temperature rose to about 70°C impacting negatively on electricity production.Photovoltaic water heating system may improve life span of the module and at the same time alleviate the burden of conventional energy c onsumption in South Africa for heating and lighting purposes.\n\nhttps://e vents.saip.org.za/event/7/contributions/5107/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5107/ END:VEVENT BEGIN:VEVENT SUMMARY:Variability of methanol maser in the massive star formation region s DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5109@events.saip.org.za DESCRIPTION:Speakers: jabulani Paul maswanganye (Wits University/HartRAO)\ nStar formation constitutes one of the basic problems of astrophysics due to the fact that stars are fundamental objects of astronomy. Shu et al. (1 987) reviews the theory of low mass star formation from the molecular clou d via accretion disk-outflow. The formation of high mass stars is still no t well understood. They may also be formed through accretion disk plus out flow (Shu et al. 1987) or by collision-coalescence which was proposed by Wolfire \\& Cassinelli (1987) and Bonnell et al. (1998)\, but most observ ations support the accretion disk-outflow model.\nThe brightest methanol m asers occur at 6668 MHz and 12178 MHz and are found in the star forming r egions containing very young massive protostars even before the formation of an ultracompact HII region (Longmore et al. 2007). These masers serve as useful tools to study these regions.\nThe poster will be on the analys is of the time series of 6668 MHz and 12178 MHz methanol maser emission li nes in some of the sources which were showing periodic variations in monit oring before the 26 meter Hartebeesthoek Radio Astronomy Observatory (Hart RAO) Telescope bearing failure in 2008. After the telescope was repaired i n 2010\, the programme to monitor these sources was restarted. These two m ethanol emission lines are radiatively pumped which implies that their var iability could be due to the decrease or increase in the seed photons at t he radio frequency\, or the infrared radiation field that pumps the masers . Since there has been a two year gap in the monitoring program of these s ources\, we want to establish whether the periodic variations continue. Su ch periodic behaviour has not been seen in other maser species in star f orming regions\, so it can provide new insights into what is happening in these regions.\n\nhttps://events.saip.org.za/event/7/contributions/5109/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5109/ END:VEVENT BEGIN:VEVENT SUMMARY:Observations of the 22GHz Water maser in the source Orion KL DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5110@events.saip.org.za DESCRIPTION:Speakers: Sunelle Otto (HartRAO)\nStars are believed to be for med from massive stable gas clouds\, which under enough perturbation will collapse to form a protostar. The protostar evolves to form a star by accr eting matter until the fusion is initiated in the dense core. Surrounding these protostars are ionized hydrogen (HII) regions and molecule species w here masing occurs. MASER is an acronym for Microwave Amplification by Sti mulated Emission of Radiation. It is here that Water masers are also found . Amongst the sources of water masers\, is the Orion KL source region. Fl ares in this region from the 1.35cm water maser emission line occurred in 1984\, with the second flare in 1998 and again this year (2011) there have been reports of the flare. The flare is very intense\, increasing its fl ux density from around hundreds to millions of janskies. This poster will show the summary of observations made by the Hartebeesthoek Radio Astronom y Observatory (HartRAO) telescope for the water maser in the Orion KL sour ce region as well as the calibration method. Jupiter is used as the calibr ator source\, while the absorption by atmospheric water vapour must also b e allowed for. This uses estimates based on atmospheric temperature and hu mdity or can also be based on the time delay of GPS signals\, corrected fo r barometric pressure.\n\nhttps://events.saip.org.za/event/7/contributions /5110/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5110/ END:VEVENT BEGIN:VEVENT SUMMARY:Space Weather Prediction and Forecast in South Africa DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5114@events.saip.org.za DESCRIPTION:Speakers: Mpho Tshisaphungo (SANSA Space Science)\nSpace weath er describes the conditions in space that affect both Earth- and Space bou nd technological and biological systems. It is a consequence of the behavi or of the Sun\, the nature of the Earth’s magnetic field and atmosphere\ , and our location in the solar system. Space weather is one of the princi pal threats to modern technology. With the increase in technological syste ms the need for accurate space weather predictions and forecasts has incre ased. The paper presents the space weather predictions and forecasts done by African Space Weather Centre at the Hermanus Magnetic Observatory (HMO) . The African Space Weather Centre has been appointed by ISES (Internation al Space Environment Service) as the Regional Warning Center (RWC) for Afr ica.\n\nhttps://events.saip.org.za/event/7/contributions/5114/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5114/ END:VEVENT BEGIN:VEVENT SUMMARY:Simulating chorus generation via Particle-in-cell simulations DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5123@events.saip.org.za DESCRIPTION:Speakers: Marlie van Zyl (University of KwaZulu Natal)\nChorus emissions are whistler mode waves propagating through the Earth’s magne tosphere in two distinct frequency bands\, typically in the range of 0.1-0 .8 fce\, where fce is the equatorial electron gyro-frequency. Chorus consi sts of discrete elements\, which are normally rising tones\, each of which lasts for a few tenths of a second. Chorus is predominantly observed duri ng the onset of the substorm expansion phase when energetic electrons are injected into the magnetosphere. As these electrons drift eastward around towards noon\, their distribution becomes unstable to the amplifiation of whistler mode waves. It is thought that the amplification process proceeds via the Doppler-shifted cyclotron resonance interaction. Particle-in-cell (PIC) simulations\, which simulate the motion of groups of similar partic les on a two dimensional grid subject to the self-consistent electric and magnetic fields generated by their spatial distribution and motion\, are u sed to simulate the amplification of whistler-mode waves propagating along the magnetic field. A population of electrons having a velocity distribut ion with a thermal anisotropy is injected into the plasma and the growth o f the resulting waves is investigated.\n\nhttps://events.saip.org.za/event /7/contributions/5123/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5123/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigating the thermal performance of a hybrid PV solar system DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5126@events.saip.org.za DESCRIPTION:Speakers: Michael Simon (FHIT)\nPhotovoltaic thermal heating s ystem have gained momentum in the recent years with many investigations be been done on how to maximize the heat harnessing mechanisms. In some cas e copper tubes fixed on the back part of the module\, are used to circulat e forced water around them by external driving force e.g. pumps and\, in t he process extract heat from the module and provide the cooling effect as well. As more heat is extracted from the these devices\, the final water temperature rises above the ordinary ambient temperature and stays hot for longer hours after the sun has gone down. This effect on the performance of the PV system due to long temperature lag and uneven heat distribution on the back of the module as a result of thermodynamics processes in the water will be presented in the final paper.\n\nhttps://events.saip.org.za/ event/7/contributions/5126/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5126/ END:VEVENT BEGIN:VEVENT SUMMARY:Radiation Shielding calculations using MCNPX transport code for co st optimization of the shielding material to be used in the new cyclotron vault at iThemba Labs DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5136@events.saip.org.za DESCRIPTION:Speakers: Zipho Ngcobo (iThemba Labs)\nIon Beam Applications ( IBA) commercial cyclotron (IBA Cyclone 70) with capability of accelerating protons up to 70MeV and 350µA of current is to be constructed at iThemba Labs to increase the capacity of the current facility. The two opposite s imultaneous extraction of beams using the Carbon foil stripper\, enable fo r the concurrent production of radioactive ion beam (RIB) for nuclear rese arch and isotope production.\nThis high energy beam is expected to have lo sses of about 10% in total meaning 70µA of the total beam will interact w ith surrounding materials during acceleration. Thus this proton beam is a possible radiation source\, presenting a threat of ionising radiation. The cyclotron is mainly made of magnetic steel which is rather stable provind ing local shielding inside the vault. There are not many significant openi ngs for the radiation to rather escape in the less dense media to the surr ounding other than in the extraction sides. Between the two poles of the c yclotron\, the strip made of steel\, which seals the two poles\, is thick enough to shield radiation. Considering efficiencies at the extraction sid e of the cyclotron\, it is expected that radiation contamination will accu mulate and be transported to the vault and surroundings during cyclotron o perations.\nParticles of concern are neutrons and photons formed during pr oton beam interaction. Bremstrahlung x-rays (photons) could be from proton acceleration and neutrons could be produced by (p\, n) reactions. Photons and neutrons are not easy to shield. There is a need to simulate the radi ation transport using MCNPX transport code so that the levels of doses can be investigated to provide extra safety cautions and adequate selection o f materials and correct dimensions for shielding walls to keep the dose ra tes at acceptable levels. Additionally\, water in the cooling system as i t consists of Hydrogen isotopes that can react with protons to produce neu trons will also be investigated as it will increase the neutron flux into the vault.\n\nhttps://events.saip.org.za/event/7/contributions/5136/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5136/ END:VEVENT BEGIN:VEVENT SUMMARY:Current Status of Ultrafast Electron Diffraction at the Laser Rese arch Institute DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5160@events.saip.org.za DESCRIPTION:Speakers: Ilana Boshoff (University of Stellenbosch (Laser Res earch Institute))\nWe will show the changes and improvements made to the U ltrafast Electron Diffraction setup which led us to doing the first time-r esolved experiments. \nWe have implemented beam tracking and correction s ystems in both the pump and probe beams\, ensuring that we keep spatial ov erlap during a measurement. By using a different cathode and metal coati ng we were able to improve the electron efficiency. These improvements en able us to do measurements of up to 20 hours without losing the electron s ignal.\nPreciously a commercial 8-bit Nikon camera was used to gather data . We have switched to a 16-bit EHD CCD Camera to increase the amount of i nformation we get from one data point.\nPrevious problems concerning the b ackground were solved by reducing the electron energy and applying a small voltage to the sample holder to prevent photo electrons from reaching the detector.\nA big challenge in UED is the preparation of thin (<100nm) sam ples. We will show the techniques we use to overcome this problem.\n\nhtt ps://events.saip.org.za/event/7/contributions/5160/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5160/ END:VEVENT BEGIN:VEVENT SUMMARY:Cross phase modulation induced depolarization of a probe signal an d its impact on polarization mode dispersion compensators DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5158@events.saip.org.za DESCRIPTION:Speakers: Timothy Gibbon (Nelson Mandela Metropolitan Universi ty)\nNonlinear effects are easily observed in single mode optical fibres b ecause of the fibre small spot size and extreme low loss. At high optical intensities in fibres the refractive index becomes a function of the inten sity of the optical signal. This refractive index is known as the Kerr non linearity. This leads to the optical Kerr effect where the nonlinear phase shift induced by an intense high power pump changes the characteristics o f the probe beam. Cross phase modulation (XPM) refers to a nonlinear effec t where a pump beam with high intensity changes the phase of a low power p robe beam.\nIn this work\, we consider the composite problem of polarizati on mode dispersion (PMD) and XPM in wavelength division multiplexing (WDM) networks. PMD continues to pose a treat to high speed optical networks he nce the need for PMD compensators (PMDCs). PMDCs monitor the link PMD in a n indirect manner where a popular monitoring technique tracks the degree o f polarization (DOP) of a signal in the link. It can be shown that in a tw o channel WDM system an intensity modulated pump modulates the state of po larization (SOP) of a probe signal at the pump bit rate. In this work we e xperimentally demonstrate the depolarization of a probe signal in the pres ence of an intensity modulated pump signal. The results show that minimum interaction between the pump and probe signal occur when the pump and prob e input Stokes vectors are parallel and anti-parallel. Hence the probe sig nal incurs maximum depolarization when the two signals are arranged in an orthogonal configuration. These results are crucial to PMDC because the so urce of the DOP degradation may mislead the compensator.\n\nhttps://events .saip.org.za/event/7/contributions/5158/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5158/ END:VEVENT BEGIN:VEVENT SUMMARY:Atomic processes in gaseous nebulae DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5168@events.saip.org.za DESCRIPTION:Speakers: Andri Prozesky (Unisa)\nThe atomic physics relevant to gaseous nebulae is critically examined using modeling software with par ticular emphasis on recombination spectral lines that occur in the radio r egime. The spectral line intensities that we observe from nebulae can be d educed if we know the population structure of the bound electrons in the g as under non-thermal equilibrium conditions. The population structure of h ydrogen is solved for various environments using a capture-collision-casca de model.\n \nThe validity of assuming Case B of Baker & Menzel (1938) whe n modeling astronomical nebulae is investigated. It is known that Case B i s appropriate for levels with small principle quantum numbers (n < 40)\, b ut this assumption should be re-examined for high energy levels which are relevant to radio recombination lines.\n \nThe effect of an ambient radiat ion field on the population structure is examined and processes that are s timulated by a radiation field are included in the model. This is done as a preliminary investigation to extend the model to a full photoionization code that will be geometry-dependent and include an external radiation fie ld as well as the diffuse field that is emitted by the nebula itself.\n\nh ttps://events.saip.org.za/event/7/contributions/5168/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5168/ END:VEVENT BEGIN:VEVENT SUMMARY:Magneto-optical trap - First step towards BEC DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5183@events.saip.org.za DESCRIPTION:Speakers: Malehlohonolo Semonyo (University of KwaZulu-Natal)\ nThe experimental demonstration of Bose-Einstein Condensation (BEC) is one of the most exciting developments of recent years. It has enabled researc hers to study a macroscopic quantum object with well controllable paramete rs. This has sparked a lasting flurry of experiments covering an enormous range of fields\, which have made significant contributions to our underst anding of atomic and molecular physics\, precision metrology and future te chnologies in quantum optics and quantum information science. The success of these experiments has led to the award of several Nobel Prizes in recen t years. \n\nThe first step in the construction of an experiment for reali zing a Bose-Einstein condensation is obtaining an appropriate reservoir of cold atoms with sub-microKelvin temperatures. In our experiment\, we coo led and trapped Rubidium atoms by using a combination of lasers and magnet ic fields known as a magneto-optical trap (MOT) [2]. The MOT will be used as a reliable and robust source of cold atoms that will be cooled further to create a BEC. We report here on the construction of the MOT\, in partic ular we describe the absorption saturation spectroscopy used for locking t he lasers\, the type of lasers used as well as the construction of the mag netic coils needed for generating the field used for spatial trapping of t he atoms. We also describe the design and construction of the glass cell we used as the vacuum chamber and finally report on our main objective of realizing a BEC through evaporative cooling.\n\nhttps://events.saip.org.za /event/7/contributions/5183/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5183/ END:VEVENT BEGIN:VEVENT SUMMARY:Hi-speed Random Number Generator DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5204@events.saip.org.za DESCRIPTION:Speakers: Adedayo Olatinwo (University of Kwazulu Natal)\n Rec ently\, I . Kanter et al\, developed an Ultra fast random bit generator\, based on a semiconductor laser\, having time delayed self-feedback\, which operates reliably at rate up to 300 GB/s. The method uses a high derivati ve of the digitized laser intensity and generates the random sequence by r etaining a number of the least significant bits of the high derivative val ue. The generator is insensitive to laser operational parameters and elimi nate the necessity for all external constraints such as incommensurate sam pling rates and laser external cavity round trip time. The randomness of l ong bit string is verified by standard statistical tests\n\n An improved Random Number generator is proposed by making use of Zener noise. At the s ame time Field programmable Gateway Array for processing the final genera ted random numbers instead of using the Nth and Least Synthetic Bits (LSBS ). All the output from the FPGA will be transferred through USB cable into a connected PC where the random number is interpreted.\n\nhttps://events .saip.org.za/event/7/contributions/5204/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5204/ END:VEVENT BEGIN:VEVENT SUMMARY:Enhancement of hydrogen production using biomass gasification proc ess DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5211@events.saip.org.za DESCRIPTION:Speakers: Sampson Mamphweli (University of Fort Hare\, Institu te of Technology)\nHydrogen production from biomass holds the greatest pro mise\, since biomass is abundantly available everywhere in the world. Howe ver\, hydrogen from biomass has major challenges. The yield of hydrogen is low from biomass since the hydrogen content in biomass is low to begin wi th (approximately 6%) and the energy content is low due to the 40% oxygen content of biomass. A novel gasification method for hydrogen production fr om carbonaceous materials using a CO2 sorbent has been widely used. It mai nly uses steam as gasification agent. For this study the above method has been adopted to test if it will work for air-blown biomass gasifiers. The main purpose of this project is to enhance the yield of hydrogen from air- blown biomass gasification process. The produced hydrogen will be further separated and purified for fuel cell application. Ultimate and proximate a nalyses of the biomass material were conducted and the obtained results we re used for the simulations in order to determine the efficiency of the ga sifier with biomass and biomass/sorbent blends. It was found that the biom ass/sorbent blends increase the yield of not only H2 but also other syngas constituents such as CO leading to enhancement of the gasifier efficiency since it is dependent on the volume of combustible gases.\n\nhttps://even ts.saip.org.za/event/7/contributions/5211/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5211/ END:VEVENT BEGIN:VEVENT SUMMARY:Micromachining of optical fibers with a Nd:YAG laser at 532 nm usi ng a spatial filter DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5227@events.saip.org.za DESCRIPTION:Speakers: Diethelm Schmieder (University of Johannesburg)\nMic romachining of single-mode telecommunication fibres (SMF28) was accomplish ed with a Nd:YAG laser at a wavelength of 532 nm. The goal of the micromac hining process is to machine miniature Fabry-Perot interferometers in the fiber to manufacture fast temperature sensors. To produce micro features b y direct machining the laser beam is focused to spot sizes of 30 µm and b elow. The different shapes of the micro features are accomplished with sma ll apertures in close proximity and in line with the machining lens (focal length 24.5 mm). \n\nWe describe the experimental setup and the monitorin g process. Two mirrors BB1-E02 were installed at an angle of 45 degrees to eliminate the infrared radiation at 1.064 µm. The apertures in line with the machining lens are projected onto the fiber\, which was mounted on a three axis translation stage. The apertures could also be projected agains t the wall to assure homogeneous illumination. The fiber can be shifted be tween the machining area and a camera with 400 x magnification. The images are recorded with ProScope software\, stored in a computer and displayed on a screen.\n\nThe focal point is established by generating a white light supercontinuum by air breakdown. The centre position on the fibre is foun d with the help of the diffraction pattern produced by the fibre. The mach ining frequency was 10 Hz and we found the best laser beam powers between 1 – 3 mW or 0.1 – 0.3 mJ/pulse. We managed to machine right through t he fiber. The machining results will be presented.\n\nhttps://events.saip. org.za/event/7/contributions/5227/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5227/ END:VEVENT BEGIN:VEVENT SUMMARY:Super star clusters in nearby Luminous Infrared Galaxies DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5229@events.saip.org.za DESCRIPTION:Speakers: Zara Randriamanakoto (University of Cape Town)\nApar t from the presence of an active AGN\, very young and massive super star c lusters (SSCs) are likely \nto be found in local starbursts and interactin g luminous infrared galaxies. SSCs are responsible of a high \nstar format ion rate (SFR) of the host galaxy. From an on-going deep NIR AO imaging s urvey\, we were able to observe some\nSSCs hidden by the dusty central reg ions. To better understand the formation and the evolution of massive star \nclusters we derived the K-band SSC luminosity functions (LFs) of our sam ple.\n\nhttps://events.saip.org.za/event/7/contributions/5229/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5229/ END:VEVENT BEGIN:VEVENT SUMMARY:Intra-cavity beam control: a comparison of spatial light modulator s and adaptive mirrors DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5234@events.saip.org.za DESCRIPTION:Speakers: Liesl Burger (National Laser Centre)\nIt is well und erstood that the fundamental mode of a cavity may be selected by suitable choice of intra-cavity amplitude or phase elements. If one wishes to dyna mically control the mode\, for example\, to manage thermal aberrations\, t hen intra-cavity elements that are controllable are required. Two such el ements are adaptive mirrors and spatial light modulators (SLMs). In this poster we present early results on the intra-cavity use of SLMs\, and high light some expected and unexpected problems. We then compare our results to our first attempts at the use of an intra-cavity adaptive mirror.\n\nht tps://events.saip.org.za/event/7/contributions/5234/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5234/ END:VEVENT BEGIN:VEVENT SUMMARY:Developing a laser ionization test bench for radioactive beams DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5235@events.saip.org.za DESCRIPTION:Speakers: Lucky Makhathini (University of Zululand\, stellenbo sch and iThemba labs)\nNuclear reactions employed in the production of neu tron-rich radioactive beams often produce many species simultaneously. To extract these beams\, they must not only be ionized\, but ionized selecti vely\, so that only the desired species is extracted.\nWe are developing t he laser resonant ionization technique to fulfil these requirements. The m ethod makes use of high power pulsed lasers\, making it possible to assume that the ionization probability of atoms entering the laser beam zone wil l be close to 100%. A test setup-is being developed to ionize stable atoms . In our test bench\, a stream of atoms is produced by evaporation. Atoms in the stream are ionized by lasers and transported to an ion detector wit h the assistance of an electric field. Ionization can be either non-resona nt through a continuum of levels or resonant through excitation of an auto -ionizing state. For efficient atom ionization the transition must be satu rated at all excitation stages. The condition of saturation means 100% pro bability of excitation of all atoms in the laser radiation zone in the tim e shorter than the life time of the level being excited. \nThe lasers that are employed are the excimer laser and dye laser. The excimer laser is us ed to pump the dye laser and the dye laser is used to tune the wavelength. Instruments such as Fabry-Perot interferometers and diffraction gratings are used to select the wavelength required. The laser beam for ionization is directed to the chamber by means of mirrors and lenses.\nSeparation of ion makes it possible to obtain individual spectra of each ion without the use of mass separator.\n\nhttps://events.saip.org.za/event/7/contribution s/5235/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5235/ END:VEVENT BEGIN:VEVENT SUMMARY:Identification of isotopes using time differential\, event-by-even t gamma spectroscopy DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5252@events.saip.org.za DESCRIPTION:Speakers: Martin Cook (University of Johannesburg)\nIn the con text of activation studies\, in order to uniquely identify an isotope via gamma spectroscopy\, both the lifetime and the energy of the emitted gamma rays are required. Traditional detectors collect only integral data\, los ing information about the timing of individual events. This makes lifetime analysis a manually intensive task\, as data points must be obtained by c ycling the target in front of the detectors for well defined times at well defined intervals. Lifetime accuracy is limited by the manual details of this cycling procedure. \n\nA gamma spectroscopy system based on event-by- event acquisition implemented on the VME standard offers the advantage of recording time-stamped energy data for each event. The system described is capable of both coincident and single photon detection - enabling in addi tion the identification of PET isotopes amongst the other nuclides. The da ta can then be analyzed offline in a time differential manner\, to provide both the gamma-line energy and lifetime. If necessary\, the lifetime anal ysis can accommodate correlated and uncorrelated multiple lifetimes. One d etection run will therefore yield complete information about both the ener gies and lifetimes of all isotopes present\, allowing for unique isotope i dentification.\n\nThis poster outlines this technique\, then goes on to sh ow results from its application to the study of isotopes excited when an e lectron beam is incident on high Z targets. These experiments were conduct ed in the context of obtaining activation data for a diamond sorting techn ique based on positron emission tomography.\n\nhttps://events.saip.org.za/ event/7/contributions/5252/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5252/ END:VEVENT BEGIN:VEVENT SUMMARY:X-ray Timing and Spectral Analysis of the Propeller Driven Pulsar- like White Dwarf AE Aquarii DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5262@events.saip.org.za DESCRIPTION:Speakers: Bosco Oruru (University of the Free State)\nThe high ly transient multi-wavelength system AE Aqr consists of a fast rotating hi ghly magnetic WD\, accreting mass from a K3-5 secondary companion. This ma gnetic CV has a characteristic orbital period of 9.88 h\, and is in a prop eller state. The turbulent interaction between the fast spinning WD magnet osphere and the accretion flow is believed to play a crucial role in the m ulti-wavelength emission in the system. We have analysed the system's X-ra y lightcurves and spectra from data observed with Chandra and Swift-XRT\, and the results of this study show that the X-ray characteristics are uniq ue. In this paper\, the results of the analysis will be discussed\, with t he view to propose suitable models for the X-ray emission mechanisms.\n\nh ttps://events.saip.org.za/event/7/contributions/5262/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5262/ END:VEVENT BEGIN:VEVENT SUMMARY:Radon from building materials DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5269@events.saip.org.za DESCRIPTION:Speakers: RABECCA RAMOKONE THELEDI (UWC)\nRadon is a naturally occurring radioactive inert gas in the decay chain of uranium-238. High radon levels in houses have been linked to the occurrence of lung cancer via the deposition of radon progeny in the lungs.\nThe radon activity in h ouses depends on the concentration of radium in the soil below the house a nd the diffusion of radon into the house. Another pathway is the concentra tion of radium in building materials. There has been concerns that indoor radon from granite countertops and zircon tiles might contribute signific antly to the radon concentration in a house. \nThe aim of this work is to look at how much radon is coming out of some South African tiles and gran ite used in houses\, as well as other building materials. Radium content has been measured using a NaI detector and radon with the use of a RAD7 co ntinuous radon monitor as well as electrets ion chambers. Preliminary meas urements will be presented on material that has been used in construction in South Africa.\n\nhttps://events.saip.org.za/event/7/contributions/5269/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5269/ END:VEVENT BEGIN:VEVENT SUMMARY:KIC Rumple\, the binary system with eclipses and δ Scuti pulsatio ns DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5272@events.saip.org.za DESCRIPTION:Speakers: Christopher Middleton (University of Johannesburg)\n Studying pulsating stars in Eclipsing binaries has the potential to be an exacting test of theoretical stellar models as a result of the large numbe r of constraints physically that can be imposed on individual components i n the binary system. In this particular example\, Kpl Rumple\, the measur ement of the large number of frequencies in the star of precisely known ma ss and radius from binary modelling will enable the identification of puls ation modes. This is vital as a proper physical understanding of δ Scuti pulsations will ensue. It also holds the promise of direct detection of th e spatial distribution of pulsations on stellar surfaces.\n\nAsteroseismol ogy is the ultimate goal: the derivation of internal rotational behaviour in stars\, accurate determination of stellar aging with associated metalli cities and the determination of the amount of convective core overshooting in stellar interiors.\n\nThe research involves the analysis of data obtai ned through membership of the Kepler Asteroseismic Consortium Working Grou p 9\, analysing proprietary data received from the Kepler Space Telescope. \n\nThe data are de-trended\, and subject to refined sophisticated analys is routines using many software platforms based on sound physical principl es in the determination of the binary parameters and pulsating frequencies of the pair. \n\nAnticipated conclusions that might be derived from the c onclusion of this project are discussed.\n\nhttps://events.saip.org.za/eve nt/7/contributions/5272/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5272/ END:VEVENT BEGIN:VEVENT SUMMARY:Simple Pendulum: A first year students' dilemma. DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5279@events.saip.org.za DESCRIPTION:Speakers: Itumeleng Phage (Honorary)\nInvestigation of the Fir st-year students' abilities to use mathematical concepts of straight line equation and graph to analyse Physics properties with particular reference s to a Simple Pendulum motion experiment.\n\nhttps://events.saip.org.za/ev ent/7/contributions/5279/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5279/ END:VEVENT BEGIN:VEVENT SUMMARY:PLASMON: Data Assimilation of the Earth's Plasmasphere DTSTART;VALUE=DATE-TIME:20110714T150000Z DTEND;VALUE=DATE-TIME:20110714T170000Z DTSTAMP;VALUE=DATE-TIME:20260613T214401Z UID:indico-contribution-291-5280@events.saip.org.za DESCRIPTION:Speakers: Andrew Collier (Hermanus Magnetic Observatory)\nThe principal source and loss mechanisms in the Earth's radiation belts are cu rrently not completely understood. Loss rates are important since they det ermine the duration of exposure of satellites to enhanced radiation condit ions during a geomagnetic storm. The dominant loss process is relativistic electron precipitation via resonant interactions with a variety of wave m odes. These interactions are governed by the characteristics of the plasma sphere. Current models provide an inadequate representation of the spatial and temporal evolution of the plasmasphere. In situ measurements of the p lasmasphere provide only local characteristics and are thus unable to yiel d a complete global picture. Ground based measurements\, based on the anal ysis of Very Low Frequency (VLF) whistlers and Field Line Resonances (FLRs )\, are able to describe large sections of the plasmasphere\, extending ov er significant radial distances and many hours of local time. These measur ements provide electron number and plasma mass densities.\n\nPLASMON is a funded FP7 project between 11 international partners. PLASMON intends to a ssimilate near real time measurements of plasmaspheric densities into a dy namic plasmasphere model. The VLF whistler analyses will be conducted by a utomatic retrieval of equatorial electron densities using data from AWDAne t. Equatorial mass densities will be constructed from FLR measurements alo ng meridional magnetometer chains. The resulting model will facilitate the prediction of precipitation rates. The predicted rates will be compared t o observations from the AARDDVARK network.\n\nhttps://events.saip.org.za/e vent/7/contributions/5280/ LOCATION: Asteria URL:https://events.saip.org.za/event/7/contributions/5280/ END:VEVENT END:VCALENDAR