Comparison Of Meteorological Drought Indices In Tanzania Using The Meteorological Drought Monitoring Software Package,
2024
Environmental and Atmospheric Sciences Group, Department of Physics, University of Dar es Salaam, P. O. Box 35063, Dar es Salaam, Tanzania
Comparison Of Meteorological Drought Indices In Tanzania Using The Meteorological Drought Monitoring Software Package, Paul Ts Limbu
Tanzania Journal of Engineering and Technology (TJET)
Low precipitation, substantial evaporation, and an unequal distribution of precipitation throughout the area are the characteristics of drought, a climatic abnormality. This study used the Meteorological Drought Monitoring (MDM) software and monthly rainfall data from the Tanzania Meteorological Authority (TMA) to examine and compare the Deciles Index (DI), Standardised Precipitation Index (SPI), Percent of Normal Index (PNI), Rainfall Anomaly Index (RAI), Z-Score Index (ZSI), China-Z Index (CZI), and Modified China-Z Index (MCZI) for drought monitoring in Tanzania from 1988 to 2017. It was found that ZSI represented the dry years better than other indices, followed by DI, RAI, PNI, SPI, …
An Optimization Tool For A Standalone Photovoltaic System,
2024
Department of Mechanical and Industrial Engineering, College of Engineering and Technology, University of Dar es Salaam
An Optimization Tool For A Standalone Photovoltaic System, Johanes Kasilima
Tanzania Journal of Engineering and Technology (TJET)
Stand-alone photovoltaic systems (SAPV) are often used in remote areas where access to grid electricity is limited. This system depends on solar energy. However, Photovoltaic (PV) systems need a greater initial investment than conventional sources of energy, and their effectiveness is reliant on a number of environmental conditions such as the unpredictable solar radiation. One step in reducing the investment cost of a PV system is determining the optimal size of solar PV components that minimize costs. This paper presents a Particle Swarm based optimization tool for sizing Stand-alone PV systems. The optimization tool selects the optimal Levelized Cost of …
Study Of Indium-Silicon Co-Doped Gallium Oxide For Effective N-Type Doping,
2024
University of South Carolina
Study Of Indium-Silicon Co-Doped Gallium Oxide For Effective N-Type Doping, Muhammad Hassan Tahir, Nifat Jahan, Md Ghulam Zakir
Faculty Publications
We present the research efforts to achieve effective n-type doping in gallium oxide (Ga2O3), an ultrawide bandgap semiconductor, grown by metal-organic chemical vapor deposition (MOCVD). The application of semiconductors for power electronics requires wide and ultrawide bandgap materials that can be doped to create higher electron (n-type) or hole (p-type) densities. Ga2O3, with a bandgap of 4.9 eV, is an emerging and promising material. The bandgap of Ga2O3 is much higher than other wide bandgap material that have been adopted by or in the process of adoption by the industry for power electronics. However, the doping of Ga2O3 has some …
Gallium Oxide Based Avalanche Photo Detector,
2024
University of South Carolina
Gallium Oxide Based Avalanche Photo Detector, Muhammad Hassan Tahir Mr, Nifat Jahan, Md Ghulam Zakir
Faculty Publications
Gallium oxide (Ga₂O₃), an ultrawide bandgap semiconductor with a bandgap of 4.6 eV and a high critical electric field of 10.3 MV/cm, offers strong potential for high-performance avalanche photodetectors (APDs). This project explores the design and characterization of a Ga₂O₃-based APD featuring doped and undoped epitaxial layers optimized for high electric field generation and low thermal conductivity, enabling stable operation in high-temperature environments. Simulation results show a uniform electric field of 1 MV/cm under a 100 V applied bias, while material characterization confirms excellent surface smoothness with a mean roughness of ~1.1 nm and an electron mobility of 21.7 cm²/V·s …
Exploring Various Integration Methods Of Carbon Quantum Dots In Cspbcl3 Perovskite Solar Cells For Enhanced Power Conversion Efficiency,
2024
Helwan University
Exploring Various Integration Methods Of Carbon Quantum Dots In Cspbcl3 Perovskite Solar Cells For Enhanced Power Conversion Efficiency, Eman Sawires, Zahraa Ismail, Mona Samir, Ahmed Agour, Fathy Amer, Hassan Nageh, Sameh O. Abdellatif
Electrical Engineering
No abstract provided.
Effect Of Fabrication Parameters On The Ferroelectricity Of Hafnium Zirconium Oxide Films: A Statistical Study,
2024
Air Force Institute of Technology
Effect Of Fabrication Parameters On The Ferroelectricity Of Hafnium Zirconium Oxide Films: A Statistical Study, Guillermo A. Salcedo, Ahmad E. Islam, Elizabeth Reichley, Michael Dietz, Christine M. Schubert Kabban, Kevin D. Leedy, Tyson C. Back, Weison Wang, Andrew Green, Timothy S. Wolfe, James M. Sattler
Faculty Publications
Ferroelectricity in hafnium zirconium oxide (Hf1−xZrxO2) and the factors that impact it have been a popular research topic since its discovery in 2011. Although the general trends are known, the interactions between fabrication parameters and their effect on the ferroelectricity of Hf1−xZrxO2 require further investigation. In this paper, we present a statistical study and a model that relates Zr concentration (x), film thickness (tf), and annealing temperature (Ta) with the remanent polarization (Pr) in tungsten (W)-capped Hf1−xZrxO2. …
Exploring The Morphological Surface Resistance And Optical Absorption Of Thin Black Carbon Nanotube Films For Electronic And Optoelectronic Devices, Ziad Khalifa, Sameh Osama Abdellatif
Chemical Engineering
This study investigates the optical and electrical properties of thin black films of carbon nanotubes (CNTs) fabricated under various conditions to explore their potential integration as either a perfect broadband absorber or enhanced counter electrode. The study involves SEM measurements, surface resistance measurements, and UV–Vis. spectrometer analysis. The results show that the CNT thin films exhibit high electrical conductivity and strong light absorption across various wavelengths. Optically, we investigated the impact of varying the growth temperature and catalyst temperature on the absorption profile of the thin films. The fabricated and deposited CNTs showed broadband absorption spectra, reaching 92.8% of the …
The Impact Of N-Doped Carbon Quantum Dots On Dye-Sensitized Solar Cells Operating Under Diffused- And Low-Light Intensity,
2024
The British University in Egypt
The Impact Of N-Doped Carbon Quantum Dots On Dye-Sensitized Solar Cells Operating Under Diffused- And Low-Light Intensity, Mona Samir, Ahmed Agour, Zahraa Ismail, Hassan Nageh, Sameh O. Abdellatif
Electrical Engineering
This study investigates the double role of N-doped carbon quantum dots (N-CQDs) in dye-sensitized solar cells (DSSCs) that operate under diffused- and low-light intensity conditions. We demonstrate that the incorporation of N-CQDs leads to a substantial improvement in the performance of DSSCs. Under standard one-sun illumination, the maximum power conversion efficiency (PCE) achieved with N-CQDs is 2% higher than that of the bare cell. Moreover, we introduce two new metrics, the diffused-light coefficient and the low-light intensity coefficient, to evaluate the performance of DSSCs under nonideal illumination conditions. The diffused-light coefficient is recorded at 1.55, which indicates a notable enhancement …
Impact Of Chips And Science Act Of 2022 On China's Related Industries And Policy Suggestions,
2024
School of Economics and Management, University of Chinese Academy of Sciences, Beijing 100190, China
MOE Philosophy and Social Science Laboratory of Digital Economic Monitoring, Forecasting, Early Warning, and Policy Simulation (Cultivation) University of Chinese Academy of Sciences, Beijing 100190, China
Impact Of Chips And Science Act Of 2022 On China's Related Industries And Policy Suggestions, Jiuling Shi, Yongmiao Hong, Ying Liu
Bulletin of Chinese Academy of Sciences (Chinese Version)
As the cornerstone of modern information technology, chips are the strategic commanding heights of competition game and industrial development of countries all over the world. In recent years, the United States has taken advantage of its technological advances to successively introduce chip laws against China, which seriously violates the laws of market economy and has a significant impact on the global semiconductor industry chain. This study first sorts out the development pattern of the global semiconductor industry, and then introduces the background, content and purpose of CHIPS and Science Act of 2022. Then, it analyzes the impact of the …
Exploring Forward Scattering Mechanisms In Tio2 With Carbon Quantum Dots: Insights Into Photovoltaic Applications,
2024
The Electrical Engineering department and FabLab, Centre for Emerging Learning Technologies CELT, British University in Egypt (BUE), Cairo, 11387, Egypt
Exploring Forward Scattering Mechanisms In Tio2 With Carbon Quantum Dots: Insights Into Photovoltaic Applications, Mona Samir, Zahraa Ismail, Ahmed M. Agour, Hassan Nageh, Sameh O. Abdellatif
Electrical Engineering
No abstract provided.
Machine Learning Algorithms In Photovoltaics: Evaluating Accuracy And Computational Cost Across Datasets Of Different Generations, Sizes, And Complexities,
2024
The British University in Egypt
Machine Learning Algorithms In Photovoltaics: Evaluating Accuracy And Computational Cost Across Datasets Of Different Generations, Sizes, And Complexities, Omar Elsaban, Muath Alkadi, Saif Qaid, Abdullah Ahmed, Sameh O. Abdellatif
Electrical Engineering
This paper evaluates the compatibility of five different machine learning (ML) algorithms for analyzing datasets extracted from solar cell devices. The selected ML algorithms span a range of complexity, from linear regression and polynomial regression models to random forest (RF), neural network, and a hybrid version of the latter two. The algorithms underwent testing with and without hyperparameter optimization to tune the model parameters. The study investigated the expected increased computational cost resulting from hyperparameter optimization, with improved ML accuracy. Additionally, five distinct datasets were utilized to measure the performance of the ML models across different dataset characteristics, including dataset …
Enhancing Electromigration Reliability In Solder Interconnects Through Microstructure Control And Thermomechanical Failure Mechanisms In Thin Metal Lines Under Surge Current Conditions,
2024
University of Texas at Arlington
Enhancing Electromigration Reliability In Solder Interconnects Through Microstructure Control And Thermomechanical Failure Mechanisms In Thin Metal Lines Under Surge Current Conditions, Hariram Mohanram
Material Science and Engineering Dissertations - Archive
The relentless miniaturization of semiconductor devices has intensified reliability challenges in electronic packaging, particularly for solder interconnects and thin metal lines. This dissertation investigates two critical failure mechanisms—electromigration (EM) and thermomechanical fatigue (TMF)—and explores strategies to mitigate these effects. Electromigration, driven by high-density current-induced atomic migration, significantly impacts solder interconnects. This study examines the role of Under-Bump Metallization (UBM) and solder microstructure in improving EM reliability. Findings reveal that thicker UBMs delay void nucleation and enhance EM resistance, while the absence of UBM leads to failure through vertical void propagation. Additionally, grain orientation, particularly the c-axis alignment in Sn grains, …
Analysis Of Noise Sources In Avalanche Region Of Reverse Biased P-N Junctions,
2024
University of Texas at Arlington
Analysis Of Noise Sources In Avalanche Region Of Reverse Biased P-N Junctions, Md Sakiul Islam Sudman
Electrical Engineering Theses - Archive
There is a need to understand the physical mechanisms for excess noise factor (F) in avalanche diodes for all regions of operation. The current classical theory accounts for F only for low carrier multiplication where single carrier injection starts the avalanche process. Our model fits the white noise exhibited by reverse-biased avalanche diodes in the entire operation region of four orders of current magnitude. In this sense, it is a first. The measured noise data was provided by Texas Instruments. We fitted the measured noise components with the calculated noise components where carrier multiplication takes place. The least …
Nano-Patterned Si Structures For Optical Filters And Electro-Mechanical Relays: Fabrication, Characterization, Prospects, And Limitations,
2024
Virginia Commonwealth University
Nano-Patterned Si Structures For Optical Filters And Electro-Mechanical Relays: Fabrication, Characterization, Prospects, And Limitations, Md Ataul Mamun
Theses and Dissertations
Nanofabrication technology, especially nanopatterning, is a rapidly advancing field that has already resulted in creating novel devices and holds promise for producing even more with unmatched performance. These techniques also allow us to gain insight into physical phenomena at the micro- and nanoscale. The ultimate performance of nanofabricated devices and their compatibility with existing Si-based CMOS technology hinge upon the careful selection of materials and precise design, coordinated with meticulous pattern transfer. In this work, we applied nanopatterning techniques on silicon to create optical filters for the shortwave infrared (SWIR) region and nanoelectromechanical system (NEMS) relay-based logic gates. Additionally, these …
Semiconductor Photonic Crystal Surface Emitting Lasers For High Power, High Brightness And High Speed Applications,
2024
University of Texas at Arlington
Semiconductor Photonic Crystal Surface Emitting Lasers For High Power, High Brightness And High Speed Applications, Chhabindra Gautam
Electrical Engineering Dissertations - Archive
Photonic Crystal Surface Emitting Laser (PCSEL) is the promising third generation semiconductor laser technology as it addresses the challenges of the conventional semiconductor lasers (EEL/VCSEL) by providing single mode high power output with good beam quality (thus high brightness). The large area in plane coupling resulting from the multiple Bragg’s diffraction conditions in the periodic 2D photonic crystal cavities in the lasing cladding region leads to single mode operation over very large area. By model design engineering, such in plane lasing cavity can leak the light out of the plane, which result in surface emission. The ability to scale the …
Grid Culture,
2024
CUNY Graduate Center
Grid Culture, Eliot Bates, Arseni Troitski
Publications and Research
In this essay, we provide our initial ethnographic research about lines, which at a superficial level can be considered a platform, but which is also synonymous with a community of 8800 users, and with 606k unique posts authored by these users that in aggregate constitute a discourse network (Aufschreibesysteme, see Kittler 1990). lines—as platform, community, and discourse network—is primarily designed to support the development, documentation and user-generated code efforts specific to a set of hardware synthesis-related objects (the two we will focus on are called Norns and Grid; we’ll discuss what they are and what they do through the subsequent …
Gas Assisted Electron Beam Patterning Processes,
2024
University of Kentucky
Gas Assisted Electron Beam Patterning Processes, Deepak Kumar
Theses and Dissertations--Electrical and Computer Engineering
Radiolysis is a complex phenomenon in which molecules subjected to ionizing radiation form new chemical species. Electron-beam irradiation has proven to be a versatile approach for significantly altering materials’ properties and forms the basis for electron-beam lithography using both organic and inorganic resists. Electron-beam exposure is normally carried out under high vacuum conditions to reduce contamination and allow for unhindered interaction between the electrons and the resist material. Exposure under an ambient gas at sub-atmospheric pressures has been found to provide a distinct mechanism which can be exploited to circumvent some of the challenges associated with material processing and significantly …
Reinventing Integrated Photonic Devices And Circuits For High Performance Communication And Computing Applications,
2024
University of Kentucky
Reinventing Integrated Photonic Devices And Circuits For High Performance Communication And Computing Applications, Venkata Sai Praneeth Karempudi
Theses and Dissertations--Electrical and Computer Engineering
The long-standing technological pillars for computing systems evolution, namely Moore's law and Von Neumann architecture, are breaking down under the pressure of meeting the capacity and energy efficiency demands of computing and communication architectures that are designed to process modern data-centric applications related to Artificial Intelligence (AI), Big Data, and Internet-of-Things (IoT). In response, both industry and academia have turned to 'more-than-Moore' technologies for realizing hardware architectures for communication and computing. Fortunately, Silicon Photonics (SiPh) has emerged as one highly promising ‘more-than-Moore’ technology. Recent progress has enabled SiPh-based interconnects to outperform traditional electrical interconnects, offering advantages like high bandwidth density, …
Photoluminescence Switching In Quantum Dots Connected With Carboxylic Acid And Thiocarboxylic Acid End-Group Diarylethene Molecules,
2024
University of Virginia
Photoluminescence Switching In Quantum Dots Connected With Carboxylic Acid And Thiocarboxylic Acid End-Group Diarylethene Molecules, Ephraiem S. Sarabamoun, Pramod Aryal, Jonathan M. Bietsch, Maurice Curran, Sugandha Verma, Grayson Johnson, Lucy U. Yoon, Amelia G. Reid, Esther H. R. Tsai, Charles W. Machan, Christopher Paolucci, Guijun Wang, Joshua J. Choi
Chemistry & Biochemistry Faculty Publications
We contrast the switching of photoluminescence (PL) of PbS quantum dots (QDs) cross-linked with photochromic diarylethene molecules with different end groups, 4,4′-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] (1C) and 4,4′-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenethiocarboxylic acid] (2T). Our results show that the QDs cross-linked with the carboxylic acid end group molecules (1C) exhibit a greater amount of switching in photoluminescence intensity compared to QDs cross-linked with the thiocarboxylic acid end group (2T). We also demonstrate that regardless of the molecule used, greater switching amounts are observed for smaller quantum dots. Varying these parameters allows for the fabrication of photoswitches with tunable PL change. We relate these observations to the …
Photoluminescence Of Beryllium-Related Defects In Gallium Nitride,
2024
Virginia Commonwealth University
Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov
Theses and Dissertations
This study explores the potential of beryllium (Be) as an alternative dopant to magnesium (Mg) for achieving higher hole concentrations in gallium nitride (GaN). Despite Mg prominence as an acceptor in optoelectronic and high-power devices, its deep acceptor level at 0.22 eV above the valence band limits its effectiveness. By examining Be, this research aims to pave the way to overcoming these limitations and extend the findings to aluminum nitride and aluminum gallium nitride (AlGaN) alloy. Key contributions of this work include. i)Identification of three Be-related luminescence bands in GaN through photoluminescence spectroscopy, improving the understanding needed for further material …
