Engineering Commons^™

The Study Of Electrostatic And Magnetostatic Active Space Radiation Shielding For Deep Space Missions, Leroy A. Fung

Electrical & Computer Engineering Theses & Dissertations

A goal of the National Aeronautics and Space Administration (NASA) has been to develop technologies that will enable deep space explorations. Such missions include a prolonged stay on the Moon and the ability to sustain a long duration of travel time to Mars and beyond. Long-term human exposures to radiation are a crucial concern. Recent research has taken focus on active and passive shielding methods as a way of eliminating the hazard posed by radiation particles. Passive shielding involves the use of materials that has the ability to withstand radiation particles and reduce the dose by stopping or slowing the …

Investigation Of Potential Benefits Of Revising Exception 1 Under Florida Building Code, Energy Conservation, Section 101.4.7.1.1 Duct Sealing Upon Equipment Replacement, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

Section 101.4.7.1.1, Duct sealing upon equipment replacement (Mandatory), of the 2012 Supplement to the Florida Building Code, Energy Conservation went into effect briefly in 2013. The new section required sealing of accessible ducts at the time of HVAC equipment replacement. Exception #1 however, eliminates the requirement for ducts in conditioned space, and by doing so, effectively eliminates the sealing requirement for building cavities in conditioned space that are used as air distribution paths. However, test results show that these building cavities are often connected to adjacent unconditioned spaces, in effect they are not really in the conditioned space because they …

Quantifying The Local Density Of Optical States Of Nanorods By Fluorescence Lifetime Imaging, Jingjing Liu, Xunpeng Jiang, Satoshi Ishii, V. M. Shalaev, Joseph Irudayaraj

Birck and NCN Publications

In this paper, we demonstrate a facile far-field approach to quantify the near-field local density of optical states (LDOS) of a nanorod using CdTe quantum dot (QD) emitters tethered to the surface of the nanorods as beacons for optical readouts. The radiative decay rate was extracted to quantify the LDOS; our analysis indicates that the LDOS of the nanorod enhances both the radiative and nonradiative decay of QDs, particularly the radiative decay of QDs at the end of a nanorod is enhanced by 1.17 times greater than that at the waist, while the nonradiative decay was enhanced uniformly over the …

Novel Models And Efficient Algorithms For Network-Based Optimization In Biomedical Applications, Seyed Javad Sajjadi

USF Tampa Graduate Theses and Dissertations

We introduce and study a novel graph optimization problem to search for multiple cliques with the maximum overall weight, to which we denote as the Maximum Weighted Multiple Clique Problem (MWMCP). This problem arises in research involving network-based data mining, specifically, in bioinformatics where complex diseases, such as various types of cancer and diabetes, are conjectured to be triggered and influenced by a combination of genetic and environmental factors. To integrate potential effects from interplays among underlying candidate factors, we propose a new network-based framework to identify effective biomarkers by searching for "groups" of synergistic risk factors with high predictive …

Dc And Rf Characterization Of High Frequency Ald Enhanced Nanostructured Metal-Insulator-Metal Diodes, Olawale Adebimpe Ajayi

USF Tampa Graduate Theses and Dissertations

Metal-Insulator-Metal (MIM), Metal-Insulator-Insulator-Metal (MIIM), and Metal-Insulator-Insulator-Insulator-Metal (MIIIM) quantum tunneling diodes have been designed, fabricated, and characterized. The key interest of this work was to develop tunneling diodes capable of operating and detecting THz radiation up to 30THz, which is well beyond the operation ranges of other semiconductor-based diodes.

Al2O3, HfO2 and TiO2 metal oxides were employed for studying the behavior of metal-insulator-metal (MIM) and metal-insulator-insulator-metal (MIIM) quantum tunneling diodes. Specifically, ultra-thin films of these oxides with varied thicknesses were deposited by atomic layer deposition (ALD) as the tunneling junction material that is sandwiched between platinum (Pt) and titanium (Ti) electrodes, …

Probabilistic Analysis For Reliable Logic Circuits, Scott Blakely

Dissertations and Theses

Continued aggressive scaling of electronic technology poses obstacles for maintaining circuit reliability. To this end, analysis of reliability is of increasing importance. Large scale number of inputs and gates or correlations of failures render such analysis computationally complex. This paper presents an accurate framework for reliability analysis of logic circuits, while inherently handling reconvergent fan-out without additional complexity. Combinational circuits are modeled stochastically as Discrete-Time Markov Chains, where propagation of node logic levels and error probability distributions through circuitry are used to determine error probabilities at nodes in the circuit. Model construction is scalable, as it is done so on …

Application Of Remotely Sensed Rainfall Data In Rainfall-Runoff Modelling. A Case Of Pangani River Basin, Tanzania, Joel Nobert

Tanzania Journal of Engineering and Technology (TJET)

Rainfall runoff modelling in a river basin is vital for number of hydrologic application including water resources assessment. However, rainfall data from sparse gauging stations are usually inadequate for modelling which is a major concern in Tanzania. This study presents the results of comparison of Tropical Rainfall Measuring Mission (TRMM) satellite rainfall products at daily and monthly time-steps with ground stations rainfall data; and explores the possibility of using satellite rainfall data for rainfall runoff modelling in Pangani River Basin, Tanzania. Statistical analysis was carried out to find the correlation between the ground stations data and TRMM estimates. It was …

Analysis Of Different Techniques For Improving Performance Of Flat Plate Solar Collectors For Fruits Drying, Godfrey Mbabaye

Tanzania Journal of Engineering and Technology (TJET)

Fruits drying had become a broader technology in fruits and vegetables value addition. The technology is reported to be a promising way of drying without incurring higher cost but its adaptation has not been feasible in rural areas. Solar dryers have been developed but its poor performance limits its applicability. In this study, several techniques for modifications of traditional solar collector were addressed. It was observed that, varying collector designs in different techniques, a range of collector performances can be archived. The research shows that, collector efficiency can be improved by 9.6% when employing double duct counter flow compared to …

Noise Pollution In Maize Milling Smes, Erasto Elias

Tanzania Journal of Engineering and Technology (TJET)

Maize milling SMEs emit high levels of noise which can have adverse effects on human beings and therefore require controlling. This paper reports on a study that involved assessment and measurement of noise level in maize milling SMEs in DSM and Morogoro urban, gathering opinions of workers and the neighbouring population on noise problems, and suggesting solutions for noise control. Noise measurements in 41 SMEs were recorded from 89-103 dBA in DSM and 92-103 dBA in Morogoro near the milling machines. These values were higher than the safe level of 85 dBA for 8 hours working shift. Measurement also indicated …

Preliminary Test Of A Real-Time, Interactive Silent Speech Interface Based On Electromagnetic Articulograph, Jun Wang, Ashok Samal, Jordan R. Green

School of Computing: Conference and Workshop Papers

A silent speech interface (SSI) maps articulatory movement data to speech output. Although still in experimental stages, silent speech interfaces hold significant potential for facilitating oral communication in persons after laryngectomy or with other severe voice impairments. Despite the recent efforts on silent speech recognition algorithm development using offline data analysis, online test of SSIs have rarely been conducted. In this paper, we present a preliminary, online test of a real-time, interactive SSI based on electromagnetic motion tracking. The SSI played back synthesized speech sounds in response to the user’s tongue and lip movements. Three English talkers participated in this …

Anisotropy Modulations Of Femtosecond Laser Pulse Induced Periodic Surface Structures On Silicon By Adjusting Double Pulse Delay, Weina Han, Lan Jiang, Xiaowei Li, Qingsong Wang, Hao Li, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

We demonstrate that the polarization-dependent anisotropy of the laser-induced periodic surface structure (LIPSS) on silicon can be adjusted by designing a femtosecond laser pulse train (800 nm, 50 fs, 1 kHz). By varying the pulse delay from 100 to 1600 fs within a double pulse train to reduce the deposited pulse energy, which weakens the directional surface plasmon polarition (SPP)-laser energy coupling based on the initial formed ripple structure, the polarization-dependent geometrical morphology of the LIPSS evolves from a nearly isotropic circular shape to a somewhat elongated elliptical shape. Meanwhile, the controllable anisotropy of the two-dimensional scanned-line widths with different …

Lemongrass And Cinnamon Essential Oils As Vitamin C Preservatives And Flavour Enhancers In Jam, Denice Byarushengo

Tanzania Journal of Engineering and Technology (TJET)

Lemongrass and cinnamon essential oils (LEO and CEO) are natural oils with high anti oxidation capacity, pleasant flavour, and various health benefits. Their ability to preserve vitamin C and flavour in jam have not been tested. In this study the performance of two essential oils (EOs) in preserving vitamin C and improving jam flavour were investigated. The EOs were produced by hydro-steam distillation of fresh lemongrasses and cinnamon leaves using a Clevenger apparatus. Jam samples were dosed with various concentrations of either single or mixed EOs and then stored at either room or refrigeration temperature. Samples were analysed for changes …

Accuracy Of Dem-Based Topographic Data In Flood Inundation Modelling: A Case Of Wami River, Tanzania, Preksedis Ndomba

Tanzania Journal of Engineering and Technology (TJET)

Ihe objective of this Biper is to evaluate and further convnent on the accuracy of the DEW- based topographic data us input in flood mchdelling. Recent studies have indicated that hydraulic of the modified sections based on high resolution are geometrically and hydraulically similar to the measured ones, In the study hydraulic modelling intended to guide a developnent project whereby a protection embankment is contemplated. Therefore, accuracy in terns of positioning/alignment of natural features such as river banks and heights/elevarions was imperative m arrain. In order m achieve these, accuracy of various topographic data sources were qualitatively and/or quantitatively before …

Safety Verification Of Semi-Algebraic Dynamical Systems Via Inductive Invariant, Hui Kong, Fei He, Xiaoyu Song, Ming Gu, Hongyan Tan, Jiaguang Sun

Electrical and Computer Engineering Faculty Publications and Presentations

To verify the safety of nonlinear dynamical systems based on inductive invariants, key issues include defining the most complete inductive condition and discovering an inductive invariant that satisfies the specified inductive condition. In this paper, to lay a solid foundation for future research into the safety verification of semi-algebraic dynamical systems, we first establish a formal framework for evaluating the quality of continuous inductive conditions. In addition, we propose a new complete and computable inductive condition for verifying the safety of semi-algebraic dynamical systems. Compared with the existing complete and computable inductive condition, this new inductive condition can be easily …

From The Editor-In-Chief, Ibrahim A. Baggili

Journal of Digital Forensics, Security and Law

We are proud to share with you this special edition issue of the JDFSL. This year, JDFSL partnered with both the 6th International Conference on Digital Forensics and Cyber Crime (ICDF2C) and Systematic Approaches to Digital Forensic Engineering (SADFE)–two prominent conferences in our field that were co-hosted. Fifty-three papers were submitted, and the Technical Program Committee accepted only 17 after a rigorous review process.

A New Silver Electrode Based On The Composite Silver Sulfide/Attapulgite As Ionophore, Wen-Zhuo Li, Ding-Jia Xu, Jun Wang, Jian-Long Wang

Journal of Electrochemistry

A novel silver ion selective electrode with its ionophore being a kind of organic/inorganic composite composed of silver sulfide and attapulgite has been prepared. Attapulgite is a type of natural inorganic polymer which has some properties similar to zeolite, such as a higher specific surface area and plenty of intercrystalline cavities. In this work, the silver ions were firstly adosrbed in the micropores of the attapulgite, then thioacetamidetiny was selected to mix with the prepared silver ions/ attapulgite composite. Owning to the existence of sulfur atoms in the structure of thioacetamide molecules, thioacetamide molecules can react with the silver ions/attapulgite …

Surface Enhanced Raman Spectroscopic Studies Of Pyridine Adsorbed On Ti/Au@Sio2 Film Electrode, Min-Min Xu, Ke Liu, Qing-Hua Guo, Jian-Lin Yao

Journal of Electrochemistry

This study was performed based on shell-isolated nanoparticles-enhanced Raman spectroscopy (SHINERS) technology. The Au@SiO₂ nanoparticles were prepared and characterized by TEM and cyclic voltammetry. It was shown that the shell of SiO₂ was compact. The high quality signal measured by surface enhanced Raman spectroscopy (SERS) was obtained from the adsorbed pyridine on Ti/Au@SiO₂ electrode. The origin of the SERS signals was further confirmed by testing Pt and Ni electrodes. In addition, potential dependent adsorption behavior was investigated. It was found that pyridine was adsorbed parallel on the surface from -0.1 V to -0.6 V, and converted to …

Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai

Journal of Electrochemistry

The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E₀′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E₀′ on solution pH indicated …

Novel Electrochemical Interfaces Based On Functional Nanomaterials And Their Related Applications, Cheng-Zhou Zhu, Lei Han, Shao-Jun Dong

Journal of Electrochemistry

Due to the unique optical, electronic, magnetic and catalytic properties, functional nanomaterials provide new opportunities for the rapid development in a variety of disciplines and show considerable promise in different fields. Specifically, constructions of the novel electrochemical interface using various nanomaterials and exploring their advanced electrochemical properties have received great attention to develop electrochemical devices with potential applications. In this account, we focus on our up-to-date progress in the construction of novel electrochemical interfaces based on nanomaterials, mainly highlighting our research advances on electrochemical sensors, fuel cells and fluorescence spectroelectrochemistry. These novel advanced nanomaterials endow them excellent performances and open …

Preparation And Photocatalytic Properties Of Zno Nanorod Arrays On Ti Substrates, Jia-Ming Yang, Ling-Jun Han, Li-Ping Zhong, Zhen-Hai Liang

Journal of Electrochemistry

In this paper, the uniform ZnO nanorod arrays were prepared by galvanostatic electrodeposition on Ti Substrates. The morphology and structure of samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the concentration of Zn(NO₃)₂ and the deposition current on the morphology of the ZnO nanorod arrays were investigated. Photocatalytic properties of ZnO nanorod arrays were investigated by degradation of methyl orange (MO) under UV-light irradiation. The analysis revealed that the concentration of Zn(NO₃)₂ and the deposition current strongly influenced the morphology of the ZnO nanorod arrays. Compared with …

The Ionic Diffusion Model For The Solid Oxide Cathode And Its Verification By The Electrolysis Of Ta2O5 In Molten Cacl2, Hua-Lin Chen, Zhi-Yong Wang, Xian-Bo Jin, George Z. Chen

Journal of Electrochemistry

The deoxidation speed of a solid oxide cathode in molten CaCl₂ can be estimated by the PRS steady diffusion model of O^2-, which correlates the deoxidation speed with the precursor porosity, P, the metal-to-oxide molar volume ratio, R, and the cathode volume shrinkage S. The PRS model indicates that the porosity of the oxide cathode has important influence on the deoxidation speed, and provides a very simple equation for the prediction of the optimal cathode porosity. For the electrolysis of Ta₂O₅, the porosity of the cathode is better to be within 50%. …

Effects Of Conformational Transformations On Electronic Transport Properties Of Optical Molecular Switches: An Ab Initio Study, Yuan-Yuan He, Jian-Wei Zhao

Journal of Electrochemistry

A series of model molecules with 4 kinds of conformational transformations have been investigated as optical molecular switches by using density functional theory combined with nonequilibrium Green’s function method. The theoretical calculations show that molecules after conformational transformations have photoswitching characteristics. We find that the photochromic molecules with the same conformational transformation usually have a similar current on/off state when they are applied as photoshwitches. Among these transformations, the molecular switch with E(“trans”)/Z(“cis”)-isomerisation of the NN double bond has the highest current on-off ratio. The influences of the energy gap (HLG) between the highest occupied molecular orbital (HOMO) and the …

Role Of Strain On Electronic And Mechanical Response Of Semiconducting Transition-Metal Dichalcogenide Monolayers: An Ab-Initio Study, David M. Guzman, Alejandro Strachan

Birck and NCN Publications

We characterize the electronic structure and elasticity of monolayer transition-metal dichalcogenides MX2 (M = Mo, W, Sn, Hf and X = S, Se, Te) based on 2H and 1T structures using fully relativistic first principles calculations based on density functional theory. We focus on the role of strain on the band structure and band alignment across the series of materials. We find that strain has a significant effect on the band gap; a biaxial strain of 1% decreases the band gap in the 2H structures, by as a much as 0.2 eV in MoS2 and WS2, while increasing it for …

23Na Mas Nmr Spectroscopic Study Of Na2Mnpo4F As Cathode Material For Sodium-Ion Battery, Xu Hou, Gui-Ming Zhong, Xiao-Chen Lin, Zi-Geng Liu, Xiao-Biao Wu, Yong Yang

Journal of Electrochemistry

The Na₂MnPO₄F is one of the promising cathode materials for the sodium ion batteries. In the paper, we employed the ex situ X-ray diffraction and solid state NMR techniques to study the charge and discharge processes of this material, including the crystal structure and sodium sites changes. The ex situ x-ray diffraction patterns showed that two new diffraction peaks could be observed at 31^o and 36^o indicating an intermediate phase formed with the extraction of Na⁺. From the ²³Na MAS NMR spectrum of the material, three peaks were seen at -209 …

Effects Of Oxygen Coverage And Hydrated Proton Model On The Dft Calculation Of Oxygen Reduction Pathways On The Pt(111) Surface, Li-Hui Ou, Sheng-Li Chen

Journal of Electrochemistry

DFT calculation is used to study various possible steps in the oxygen reduction reaction (ORR), including the adsorption and dissociation process of O₂ and the serial protonation process of dissociated products to form H₂O on the Pt(111) surface. By using slabs of different sizes, and different numbers of pre-adsorbed oxygen atoms, the coverage effects on the pathways are investigated. The calculated results using different hydrated proton models are also compared. It is shown that the initial step of the ORR is the formation of a protonated end-on chemisorbed state of OOH*, which can transform to an unprotonated …

Investigating The Potential Of Residential District Energy, Nelson Fumo, Vicente Bortone, Juan Zambrano, Aleyani Zambrano

Mechanical Engineering Faculty Publications and Presentations

The International District Energy Association claims that district energy: improve energy efficiency, enhanced environmental protection, fuel flexibility, ease of operation and maintenance, reliability, comfort and convenience for customers, decreased life-cycle costs, decreased building capital costs, and improved architectural design flexibility. In the U.S.A. most of the installed district energy systems are found in buildings such as colleges and universities, healthcare installations, government installations, airports and community utilities, as well as industry. All these applications have proved the advantages of district energy. However, for typical neighborhoods in small cities in the U.S.A., the dispersion of the dwelling imposes additional challenges to …

Electrochemistry At Liquid/Liquid Interfaces And Its Recent Progresses, Jing Gu, Yong-Hui Qiao, Xin-Yu Zhu, Xiao-Hong Yin, Xin Zhang, Ye Chen, Zhi-Wei Zhu, Yuan-Hua Shao

Journal of Electrochemistry

Electrochemistry and electroanalytical chemistry at a liquid/liquid interface have attracted much attention in the past few decades since they have been closely related to many applications including exploration in mechanisms of extraction processes and chemical sensing, as well as investigations in phase transfer catalysis, drug release and mimicking the function of biological membranes. In this review, recent progresses in this field in the last decade, especially the investigations in microstructure of liquid/liquid interface, charge (ion and electron) transfer reactions and functionalization of liquid/liquid interfaces, are reviewed.

Numerical Solution Of Burgers' Equation Arising In Longitudinal Dispersion Phenomena In Fluid Flow Through Porous Media By Crank-Nicolson Scheme, Ravi Borana, Vikas Pradhan, Manoj Mehta

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The present paper discusses the numerical solution of the Burgers’ equation arising in longitudinal dispersion phenomenon in fluid flow through porous media. In the porous medium pure water, salt water or contaminated water disperse in longitudinal direction gives rise to a non-linear partial differential equation in the form of Burgers’ equation. The equation is solved by using Crank-Nicolson finite difference scheme with appropriate initial and boundary conditions. The longitudinal dispersion phenomenon may be miscible or immiscible fluid flow through porous media. The problem of miscible displacement can be seen in the coastal areas, where fresh water beds are gradually displaced …

Evaporation From A Capillary Tube: Experiment And Modelization, Emmanuel Keita, Pamela Faure, Stephane Rodts, Phillippe Coussot, David Weitz

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Drying is known to play a major role in soils and buildings materials. Better understanding the physics may help saving cost and energy. Thus control of the drying kinetics is a key factor. In permeable porous media, capillary forces lead to constant curvature of the air/water interface. The value of the curvature and the shape of the interface depend strongly on the pore geometry. Thus small change in their shape may lead to main change of the air/water interface as the medium desaturates. As the surface is supplied with water the drying rate remains at a constant value set by …

Experimental Study For Air Cooling Using Membrane Covered Tray, Mohamed Ali, Obida Zeitoun, Hany Al-Ansary, Abdullah Nuhait

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

An experimental study is conducted to cool the outdoor air using a humidification technique. A wind tunnel was built with a membrane covered tray serves as a test section. An outdoor air passes over a tray full of water and covered with a specific membrane. Air temperatures and relative humidity are measured before and after the tray for several air and water speeds. Air speed is measured at different locations along the centerline of the cross section. Results show that as the angle of the tray increases the air temperature drop increases which improve the efficiency of the humidification technique. …