SO2 seasonal variation and assessment of Ozone Monitoring Instrument (OMI) measurements at Sharpeville (27.86°E; 26.68°S) a South African ground-based station

In this study, seasonal, inter-annual variations of sulphur dioxide (SO₂) were analysed for Sharpeville, South Africa (27.86°E; 26.68°S) for the period 2007–2013. Sharpeville is a residential site located within a highly industrialized region. Inter-annual variations were investigated by analysis of data collated by a ground-based (GB) instrument as well as the SO₂ retrievals recorded by the Ozone Monitoring Instrument (OMI), a satellite-based sensor. The planetary boundary layer (PBL) SO₂ vertical column data recorded by OMI were converted to surface SO₂ volume mixing ratios using the pressure difference between surface and PBL. Accordingly, the OMI-derived SO₂ measurements overestimated GB values and showed a good correlation with GB data in the austral winter. Besides this, the overall comparisons i.e. their daily, seasonal, and yearly correlation studies found that OMI-derived measurements was in better agreement with GB regardless of its moderate relative percentage of difference with GB. The seasonal variations of SO₂ demonstrated that GB and OMI-derived measurements followed a general pattern of increasing trend from autumn until late winter and decreased from the onset of spring; however, the latter showed unique high SO₂ levels in summer. Together with this, the inter-annual variations of both computations displayed a small decrement in SO₂ values during the period 2011–2013. This however proved to be a stable variation when compared to other countries.     

Deposition and optoelectronic properties of ITO (In<Subscript>2</Subscript>O<Subscript>3</Subscript>:Sn) thin films by Jet nebulizer spray (JNS) pyrolysis technique

Nanocrystalline ITO thin films were deposited on glass substrates by a new spray pyrolysis route, Jet nebulizer spray (JNS) pyrolysis technique, for the first time at different substrate temperatures varying from 350 to 450 °C using a precursor containing indium and tin solution with 90:10 at% concentration. The structural, optical and electrical properties have been investigated as a function of temperature. X-ray diffraction analysis showed that the deposited films were well crystallized and polycrystalline with cubic structure having (222) preferred orientation. The optical band gap values calculated from the transmittance spectra of all the ITO films showed a blue shift of the absorbance edge from 3.60 to 3.76 eV revealing the presence of nanocrystalline particles. AFM analysis showed uniform surface morphology with very low surface roughness values. XPS results showed the formation of ITO films with In³⁺ and Sn⁴⁺ states. TEM results showed the nanocrystalline nature with grain size about 12-15 nm and SAED pattern confirmed cubic structure of the ITO films. The electrical parameters like the resistivity, mobility and carrier concentration are found as 1.82 × 10⁻³ Ω cm, 8.94 cm²/Vs and 4.72 × 10²⁰ cm⁻³, respectively for ITO film deposited at 400 °C. These results show that the ITO films, prepared using the new JNS pyrolysis technique, have the device quality optoelectronic properties when deposited under the proposed conditions at 400 °C.     

Automating factory performance diagnostics using overall throughput effectiveness (OTE) metric

The overall equipment effectiveness (OEE) metric is a powerful tool that can be used to measure performance and also perform diagnostics at the equipment level. Although important, gains made in OEE are insufficient; because the ultimate objective is a highly efficient integrated system, not brilliant individual equipment. Factory level performance monitoring and diagnostics can be facilitated by classifying the entire manufacturing system layout into unique subsystems including “series,” “parallel,” “assembly,” and “expansion.” The overall throughput effectiveness (OTE) metric is then derived for each of these subsystems. Factory level metric can be computed by synthesizing the subsystem level metrics, capturing their interconnectivity information. The objective of this paper is to present the algorithms developed to automate the factory-level performance monitoring and diagnostics process using OTE. The algorithms are implemented into a software tool called SIMPRO. SIMPRO allows factory professionals to efficiently measure performance and conduct factory level diagnostics (i.e., identify bottlenecks/hidden capacity). A glass manufacturing case study is used to illustrate automated performance diagnostics and the benefits obtained by using the approach.     

Performance improvement of electrode for polymer electrolyte membrane fuel cell

The very high power density output available from polymer electrolyte membrane fuel cells combined with low cost has high potential for commercialization. Such high power densities are attained via better utilization of Pt crystallites in the reaction layer. This enhanced performance can be achieved by making a thin catalyst layer on the membrane surface. The robustness in the front surface catalysts is essential to minimize the coagulation of Pt particles when the fuel cells are subjected to long-term operation. This robustness of the catalyst structure depends on the manufacturing processes and also the organic solvents used to make the slurry. In this work, five different electrodes were fabricated by using different fabrication procedures, and the poison effect of CO was investigated at the anode interface.