Jephias Gwamuri

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Verified

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• Doctor of Engineering
• Professor at National University of Science and Technology

Load forecasting is a technique used by power utilities to predict electricity demand to maintain the balance between supply and demand. The problem comes when the power utilities draw more than the inadvertent power from the power pool. This necessitates the need for more accurate forecasting models. In this study, a short-term load forecasting sy...

Failure to invest in newer means of generating power has resulted in decreased power generation in the backdrop of a subsequent increase in demand for power in Zimbabwe. To mitigate problems associated with energy shortages in the country which is affecting the proper running of institutions of higher learning including NUST, a PV microgrid system...

The agglomeration/dewetting process of thin silver films provides a scalable method of obtaining self-assembled nanoparticles (SANPs) for plasmonics-based thin-film solar photovoltaic (PV) devices. We show the effect of annealing ambiance on silver SANP average size, particle/cluster finite shape, substrate area coverage/particle distribution, and...

A source of large surface areas for solar photovoltaic (PV) farms that has been largely overlooked in the 13,000 United States of America (U.S.) airports. This paper hopes to enable PV deployments in most airports by providing an approach to overcome the three primary challenges identified by the Federal Aviation Administration (FAA): (1) reflectiv...

In this study applications and potential uses of 3D printing in the plastic thermoforming industry are studied. Additive manufacturing has revolutionized the modern manufacturing process and engineering design process. Thermoforming is widely used in plastic manufacturing industries to produce a range of polymer products such as products in the pac...

The study first uses numerical simulations of hexagonal triangle and sphere arrays to optimize the performance of hydrogenated amorphous silicon (a-Si:H) photovoltaic devices. The simulations indicated the potential for a sphere array to provide optical enhancement (OE) up to 7.4% compared to a standard cell using a nanosphere radius of 250 nm and...

The recent introduction of RepRap (Self-Replicating Rapid Prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered...

Scientists have begun using self-replicating rapid prototyper (RepRap) 3-D printers to manufacture open source digital designs of scientific equipment. This approach is refined here to develop a novel instrument capable of performing automated large-area four-point probe measurements. The designs for conversion of a RepRap 3-D printer to a 2-D open...

The recent introduction of RepRap (Self-Replicating Rapid Prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered...

The recent introduction of RepRap (Self-Replicating Rapid Prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered...

Solar photovoltaic (PV) devices are an established, technically-viable and sustainable solution to society’s energy needs, however, in order to reach mass deployment at the terawatt scale, further decreases in the levelized cost of electricity from solar are needed. This can be accomplished with thin-film PV technologies by increasing the conversio...

Recent numerical modeling of plasmonic metallic nanostructures have shown great potential as a method of light management in thin-film nanodisc-patterned hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells. A significant design challenge for such plasmonic-enhanced PV devices is the requirement for ultra-thin transparent conductin...

Recent numerical modeling of plasmonic metallic nanostructures have shown great potential as a method of light management in thin-film nanodisc-patterned hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells. A significant design challenge for such plasmonic-enhanced PV devices is the requirement for ultra-thin transparent conductin...

The opportunity for substantial efficiency enhancements of thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells using plasmonic absorbers requires ultra-thin transparent conducting oxide top electrodes with low resistivity and high transmittances in the visible range of the electromagnetic spectrum. Fabricating ultra-thin...

The release of the open source 3-D printer known as the RepRap (a self-Replicating Rapid prototyper) resulted in the potential for distributed manufacturing of products for significantly lower costs than conventional manufacturing. This development, coupled with open source-appropriate technology (OSAT), has enabled the opportunity for 3-D printers...

Metals in the plasmonic metamaterial absorbers for photovoltaics constitute undesired resistive heating. However, tailoring the geometric skin depth of metals can minimize resistive losses while maximizing the optical absorbance in the active semiconductors of the photovoltaic device. Considering experimental permittivity data for InxGa1-xN, absorb...

Metals in the plasmonic metamaterial absorbers for photovoltaics constitute undesired resistive heating. However, tailoring the geometric skin depth of metals can minimize resistive losses while maximizing the optical absorbance in the active semiconductors of the photovoltaic device. Considering experimental permittivity data for InxGa1-xN, absorb...

Assessing snow-related energy losses is necessary for accurate predictions of photovoltaic (PV) performance. A PV test platform with seven portrait-oriented modules placed at four tilt angles (0°, 15°, 30°, and 45°) was installed in Calumet, MI, USA, to measure the energy loss in this snowy climate. As a best-case snow-shedding configuration, simil...

This study investigates ultra-thin transparent conducting oxides (TCO) of indium tin oxide (ITO), aluminum doped zinc oxide (AZO) and zinc oxide (ZnO) to determine their viability as candidate materials for use in plasmonic-enhanced thin-film amorphous silicon solar photovoltaic (PV) devices. First a sensitivity analysis of the optical absorption f...

The recent introduction of RepRap (Self-Replicating Rapid Prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered...

Although the trend in manufacturing has been towards centralization to leverage economies of scale, the recent rapid technical development of open-source 3-D printers enables low-cost distributed bespoke production. This paper explores the potential advantages of a distributed manufacturing model of high-value products by investigating the applicat...

To study how light behaves inside a highly diffusing medium such as biological tissues; it is necessary to know the optical properties of the media. We investigated how light propagates inside turbid media by evaluating the optical properties of phantom tissues. The studies were performed, in vitro by measuring optical properties of the medium. The...

Band gap engineering provides an opportunity to not only provide higher overall conversion efficiencies of the reference AM1.5 spectra but also customize PV device design for specific geographic locations and microenvironments based on atmospheric conditions characteristic to that particular location. Indium gallium nitride and other PV materials o...

We study polarization independent improved light trapping in commercial thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic cells using a three-dimensional silver array of multi-resonant nano-disk structures embedded in a silicon nitride anti-reflection coating (ARC) to enhance optical absorption in the intrinsic layer (i-a-Si:H) f...

Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired re...

Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired re...

This chapter reviews the recent promising advances in the use of plasmonic nanostructures forming metamaterials to improve absorption of light in thin-fi lm solar photovoltaic (PV) devices. Sophisticated light management in thin-fi lm PV has become increasingly important to ensure absorption of the entire solar spectrum while reducing semiconductor...

The unrestrained combustion of fossil fuels has resulted in vast pollution at the local scale throughout the world, while contributing to global warming at a rate that seriously threatens the stability of many of the world's ecosystems. Solar photovoltaic (PV) technology is a clean, sustainable and renewable energy conversion technology that can he...

Mutoko district is one of the districts targeted for implementation of out grower Jatropha schemes. A study was conducted in Mutoko district to strengthen the understanding of the status of biofuels in Zimbabwe and its potential impact on farming systems, markets, trade and socio-economic issues in rural communities. This book explores some of thes...

Zimbabwe is currently experiencing daily load shedding as the utility power company; the Zimbabwe Electricity Supply Authority (ZESA) is failing to cope with the ever increasing energy demand. Selbourne Brooks is one of the new up-market suburbs in the city of Bulawayo where residents have been waiting to be connected to the grid for more than five...