Engineering Science and Materials Commons^™

Moisture Induced Deformations In Glulam Members - Experiments And 3-D Finite Element Model, Henry Meleki Kiwelu

Tanzania Journal of Engineering and Technology (TJET)

Experiments were performed on scaled glue laminated bending specimens to observe time dependent development of deformations during drying and wetting. Measurements determined changes in the average moisture content and external shape and dimensions between when specimens were placed into constant or variable climates. Alterations in the external shape and dimensions reflected changes in the average value and distribution of moisture and mechanosorptive creep in the glulam. The results are being used to develop a sequentially-coupled three-dimensional hygrothermal Finite Element (FE) model for predicting temporally varying internal strains and external deformations of drying or wetting solid wood structural components. The model …

Handling Of Syringe Sharps In A Non-Incineration Health Care Waste Disposal, Tito Mwinuka

Tanzania Journal of Engineering and Technology (TJET)

An attempt has been made by the R&D team of the University of Dar es Salaam to design and manufacture two needle cutter prototypes, a manually operated and an automatic needle cutter to be used in rural and urban areas, respectively. This is part of the UNDP and WHO efforts aimed at promoting the non-burn medical waste disposal technologies in developing countries such as Argentina, India, Latvia, Lebanon, Philippines, Senegal, Tanzania and Vietnam. The project also involves designing and manufacturing of the autoclaves for sterilizing of needle cutters and other infectious medical waste. The use of needle cutters in hospitals …

Preparation Of Nis2 Nanosheet And Its Application In Asymmetric Supercapacitor, Yuan-You Wang, Ya-Nan Liu, Dang-Qin Jin

Journal of Electrochemistry

In this work, the NiS₂ nanosheets have been synthesized using Ni(OH)₂  as a precursor through a sacrificial template method. The microstructure and chemical composition of as-prepared NiS₂ were characterized by XRD, EDS, BET, SEM and TEM techniques. The results showed that both Ni(OH)₂  and NiS₂  were composed of nanoplates. The electrochemical tests revealed that NiS₂ exhibited the high specific capacitance of 1067.3 F•g^-1 at a current density of 1 A•g^-1 and excellent rate performance. Furthermore, in order to evaluate the practical application of NiS₂, an asymmetric supercapacitor, NiS₂ as …

Electroactivities Of Pd/Fe3O4-C Catalysts For Electro-Oxidation Of Methanol, Ethanol And Propanol, Tao Zou, Qing-Feng Yi, Yuan-Yuan Zhang, Xiao-Ping Liu, Guo-Rong Xu, Hui-Dong Nie, Xiu-Lin Zhou

Journal of Electrochemistry

Development of palladium (Pd) catalysts with high electroactivity for alcohol oxidation is significant for alcohol fuel cells. In this work, Pd nanoparticles were formed by sodium borohydride (NaBH₄) reduction method and subsequently deposited on the surface of carbon supported ferriferrous oxide (Fe₃O₄/C) composites to obtain the Pd/Fe₃O₄-C catalysts with different Fe₃O₄ loadings. Their transmission electron microscopic (TEM) images show that the Pd nanoparticles were uniformly dispersed on the Fe₃O₄/C. Electroactivities of the prepared Pd/Fe₃O₄-C catalysts toward oxidations of C1-C3 …

Kinetics And Mechanism Toward Electrochemical Reductions Of Sodium Bromide And Methanol Over Iron Electrodes, Qun Liao, Shu-Feng Zhang, Wen-Hua Leng

Journal of Electrochemistry

It is of technological value and scientific interest to the electro-synthesis of ferrocene, conversion of carbon dioxide (CO₂) and organic electro-synthesis in non-aqueous solutions by investigating the kinetics and mechanism toward electrochemical reductions of sodium bromide (NaBr) and methanol over iron electrodes. However, few reports in the related researches are available. In this article, the kinetics and mechanism toward electrochemical reductions of NaBr and methanol over iron electrodes were examined in detail by carrying out the polarization curve and electrochemical impedance spectroscopic measurements. The results showed that methanol was the reactant, while Na⁺ ions were functioned only …

Effect Of Peg-Coating On Properties Of Lithium-Sulfur Battery Cathode Material Containing Carbon Fiber Conductive Agent, Jie-Cheng Tan, Yan-Hong Tian, Xue-Jun Zhang, Kai-Le Fan

Journal of Electrochemistry

The composite materials contained high modulus carbon fiber (HMCF) were successfully prepared by employing a ball-milling process based on the coating treatment of polyethylene glycol (PEG), and their structures and morphologies were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques．The influences of PEG content on sulfur cathode capacity, cycle stability and rate performance were systematically studied. It was found that by the pre-coating of PEG, the cathode exhibited the high initial discharge specific capacity of 1312.5 mAh⋅g^-1 at a current rate of 0.2C, and the reversible discharge capacity of 650 mAh⋅g …

Capacity Fading Analyses Of Lini0.5Co0.2Mn0.3O2And Lini0.5Co0.2Mn0.3O2/Lifepo4 Cathode Materials For Lithium-Ion Battery, Yi Hu, Xiang-Zhu He, Zhong-De Deng, Ling-Yong Kong, Wei-Li Shang

Journal of Electrochemistry

The LiNi _0.5Co _0.2Mn _0.3O₂/LiFePO₄ (NMC532/LFP) composite cathode material for lithium-ion battery was prepared by wet ball-milling. The capacity fading behaviors of LiNi _0.5Co _0.2Mn _0.3O₂ (NMC532) and LiNi _0.5Co _0.2Mn _0.3O₂/LiFePO₄ (NMC532/LFP) were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), charge/discharge and electrochemical impedance spectroscopy (EIS) tests. The results indicated that the capacity retention values of NMC532/LFP were 97.80% and 86.48%, respectively, after 50 cycles and 60℃ high temperature storage. The NMC532/LFP exhibited better cycle performance and high temperature storage performance. …

Cobalt-Based Nitrogen-Doped Carbon Non-Noble Metal Catalysts For Oxygen Reduction Reaction, Meng-Xiu Jiang, Jing Zhang, Yue-Hua Li, Rong Zhang

Journal of Electrochemistry

Transition metal-nitrogen co-doped carbon catalysts have attracted significant attention because of their reasonable activity and remarkable selectivity toward oxygen reduction reaction (ORR) as cathodic reaction in fuel cells. However, the role of transition metal in the active sites of the catalysts still is uncertain. In this work, the Co_x-N_y/C-T catalysts were prepared with BP2000 as a carbon source, urea (Ur) as a nitrogen source and Co(OAc)₂•4H₂O as a metal precursor by a simple chemical method. Meanwhile, in order to optimize the ORR activity, the catalysts were synthesized with different amounts of Co …

Core-Shell Pd@Pt Ultrathin Nanowires As Durable Oxygen Reduction Electrocatalysts, Xin Wang, Yun-Jie Xiong, Liang-Liang Zou, Qing-Hong Huang, Zhi-Qing Zou, Hui Yang

Journal of Electrochemistry

This paper describes a simple CO-assisted reduction approach for the controllable synthesis of ultrathin Pd nanowires along the one-dimensional (1D) direction. Ultrathin Pt films from one to several atomic layers were successfully decorated onto ultrathin Pd nanowires by utilizing Cu UPD deposition, and followed by in-situ redox replacement reaction of UPD Cu by Pt. The core–shell structure and composition of the Pd@Pt ultrathin nanowires have been verified using transmission electron microscopy and energy dispersive X-ray spectrometry. The core–shell Pd@Pt ultrathin nanowires exhibited comparative electrocatalytic activity and improved durability for the oxygen reduction reaction in comparison with commercial Pt black. The …

Effect Of Allyl Thiourea On Nickel Electrodeposition From Solution Containing Ammonia And Chloride, Ya-Ning He, Liang Yuan, Zhi-Ying Ding, Shi-Jun Liu

Journal of Electrochemistry

The effects of allylthiourea (ATU) concentration on the cathodic polarization behaviour, nucleation and surface morphology of nickel electrodeposited on the glassy carbon electrode from ammonia-ammonium chloride-water (NH₃-NH₄Cl-H₂O) solutions were investigated by cyclic voltammogry, cathodic polarization and current transient methods. The results revealed that the addition of ATU inhibited nickel deposition, which was enhanced with an increase in ATU concentration from 5 to 50 mg•L^-1. The initial deposition kinetics corresponded to a model including instantaneous nucleation and diffusion controlled growth. In the presence of ATU, the initial nucleation of nickel electrocrystallisation remained unchanged. …

Effects Of Jet Milling And Classifying Process On The Performance Of Lifepo4/C In Full Batteries, Xing-Liang Liu, Mao-Ping Yang, Wei-Wei Wang, Yong Cao

Journal of Electrochemistry

The carbon coated lithium iron phosphate (LiFePO₄/C) composite cathode material was prepared by using iron phosphate process. The effects of jet milling and classifying process on the electrochemical performance of LiFePO₄/C cathode material in full batteries were investigted. Scanning electron microscopic analyses suggested that the globose secondary particles were crustily crushed during the jet milling and classifying process, which would further result in lower tap density and carbon content. The LiFeP₄/C composite cathode materials with different physical characteristics were further tested in full batteries to evaluate the electrochemical properties. The results showed no obvious …

Engineering The Electrochemical Capacitive Properties Of Activated Carbon By Correct Selection Of Ionic-Liquid Electrolytes, Qiu-Hong Zhang, Bao-Shou Shen, Song-Lin Zuo, Xin-Yu Wei

Journal of Electrochemistry

In order to improve the electrochemical capacitive properties and to apply coconut shell activated carbon (AC) serving as electrode materials in ionic liquid (IL)-based supercapacitor (SC), the coconut shell AC material was re-activated using a steam as an activating agent in this work, forming a secondary AC (W-AC). The results showed that the specific capacitance of the W-AC electrode was much larger than that of the raw activated carbon electrode (R-AC) in 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF₄). The electrochemical techniques including cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) measurement, and electrochemical impedance spectroscopy (EIS) were used to systematically study the capacitive …

Applications Of N-Methyl-N-Butyl-Pyrrolidinium Bromide And N-Methyl-N-Ethyl-Pyrrolidinium Bromide In Zn-Br Flow Batteries, Qi Zhang, Miao-Miao Zhang, Lin Meng

Journal of Electrochemistry

It is extremely important for battery performance and safety in Zn-Br flow battery to use quaternary ammonium salts as complex agents for bromine. In this work, the effects of electrolyte compositions and concentrations on the electrode reactions and battery performances were studied in the absence and presences of N-methyl-N-ethyl-pyrrolidinium bromide (MEP) or N-methyl-N-butyl-pyrrolidinium bromide (MBP). The conductivities in the electrolytes containing different constitutions and concentrations were measured by EIS method. The charge-discharge performance for the battery and the complex ability for bromine in different electrolytes were also investigated. The results showed that the electrolyte containing MBP was better than that …

Effect Of Fe2+/Fe3+Interconvertion On Reduction Behavior Of Fe3+ In Acidic Electrolytes, Jian-Xin Qin, Feng Lin, Wen-Ping Liu, Chao Chen, Meng-De Ren

Journal of Electrochemistry

The influences of ferrous/ferric (Fe²⁺/Fe³⁺) interconvertion on electrochemical reduction and electrode reaction of Fe³⁺ were investigated by using linear sweep voltammetry, potentiostatic method and cyclic voltammetry (CV) in acidic electrolytes containing chloride ion (Cl^-) and sulfate ion (SO₄^2-). It was shown that the reduction process of Fe³⁺/Fe²⁺ would take place in two independent stages: (1) the reduction of Fe³⁺ to Fe²⁺ at E=0.35V and (2) the co-precipitation of Fe²⁺ by forming Fe(OH)₂ (E≤-0.3 V) instead of Fe. The major effect of Fe^{2+ …}

Effect Of Calcium On Atmospheric Corrosion Resistance Of Bridge Steel, Dong-Liang Li, Gui-Qin Fu, Miao-Yong Zhu

Journal of Electrochemistry

The corrosion behavior of bridge steel in simulated hot and humid industrial-marine atmosphere was investigated by mass loss analysis, XRD, SEM, electrochemical methods and a wet/dry alternate immersion corrosion test using 0.1 mol•L^-1 NaCl+0.01 mol•L^-1 NaHSO₃ solutions. The corrosion depth (W) of experimental steels before and after calcium treatment versus time (t) curves showed a good agreement with the power function of W=Atⁿ. The corrosion products were mainly composed of amorphous phase and a small amount of crystals including α-FeOOH, β-FeOOH, γ-FeOOH and Fe₃O₄. Trace calcium could promote the formation of …

Characterization Of Structural Dynamics Of The Human Head Using Magnetic Resonance Elastography, Andrew Arun Badachhape

McKelvey School of Engineering Graduate Student Theses & Dissertations

In traumatic brain injury (TBI), the skull-brain interface, composed of three meningeal layers: the dura mater, arachnoid mater, and pia mater, along with cerebrospinal fluid (CSF) between the layers, plays a vital role in transmitting motion from the skull to brain tissue. Magnetic resonance elastography (MRE) is a noninvasive imaging modality capable of providing in vivo estimates of tissue motion and material properties. The objective of this work is to augment human and phantom MRE studies to better characterize the mechanical contributions of the skull-brain interface to improve the parameterization and validation of computational models of TBI. Three specific aims …

Characterization And Modeling Of Asphalt Concrete For Dynamic Properties And Performances, A S M A. Rahman

Civil Engineering ETDs

The recently developed mechanistic-empirical pavement design guide (MEPDG, also known as Pavement M-E design method) uses the nationally calibrated, binder viscosity-based dynamic modulus predictive model for the design and analysis of asphalt pavements. In this study, this model is assessed for its appropriateness for asphalt-aggregate mixtures typically used in New Mexico. In essence, this study investigates the predictability issue of complex modulus of New Mexico mixes. A total of 54 Superpave mixes with different aggregate gradations, air voids, and binder grades were collected from the mixing plants and from the pavement construction sites. The loose asphalt mixtures were then compacted, …

The Inter-Laminar Shearing Effect On Wrinkle Development In Composite Forming Processes, David Sundquist

McKelvey School of Engineering Graduate Student Theses & Dissertations

Composite materials are becoming prevalent in aerospace industries as the uniqueness of the composite structure allows the composite to be tailored specifically for individual applications. Many fabrication techniques produce defects in composite parts such as wrinkles, fiber waviness, fiber misalignment, and porosity. The driving mechanisms behind these defects occurring during forming processes are not fully understood and, thus, characterization formation of these defects in a uncured state is beneficial to optimize composite processing. This work primarily investigated the influence of how uncured pre-impregnated carbon ply properties affect the wrinkling behavior of a composite laminates. Several factors affecting composite ply forming …

Functional Bio-Nano Hybrids Through A Precise Control Of Interfacial Interactions At The Nanoscale, Sirimuvva Tadepalli

McKelvey School of Engineering Graduate Student Theses & Dissertations

During the course of evolution, proteins have evolved to perform exquisite functions including structural support, signal transduction, actuation, sensing, catalysis, trafficking, gating, light-harvesting, charge transfer, molecular recognition, self-assembly, self-organization, or combinations of two or more of these functions. A precise control and manipulation of the structure and function of proteins is conceivable with the advent of nanotechnology, which has facilitated the integration of nanomaterials with functional biomolecules to realize bio-nano hybrids with synergistically enhanced functionalities.

At the genesis of bionanotechnology, a paucity in the fundamental understanding of the bio-nano interfaces is a grave impediment to the progress of the field. …

Wireless Power Transfer Roadway Integration, Trevor Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Electric vehicles represent a major accomplishment in the energy and transportation industry. Unfortunately, they are restricted to a small travel range because of limited battery life. Successful integration of wireless power transfer (WPT) systems into the infrastructure would remove the range restrictions of EVs. To successfully integrate this technology, several requirements must be met. First, the embedment process cannot interfere with the electrical performance of the inductive power transfer (IPT) system. Second, the presence of the IPT system in the pavement structure cannot negatively affect the roadway’s lifespan.

Several systems were directly embedded in roadway materials. The electrical properties of …

Optical Flow Method For Blood Flow Velocimetry Based On Digital X-Ray Subtraction Angiography: A Brief Review, Zifeng Yang

Mechanical and Materials Engineering Faculty Publications

Detailed blood flow information has been recognized as the key information for diagnosis of vascular diseases, such as vascular stenosis and aneurysms. Optical flow method (OFM) is an emergent technique as a tool to analyze the digital x-ray subtraction angiographic images of blood vessels to obtain the detailed blood flow distribution in vascular systems. A brief review isconstructed to discuss the status, applicability, accuracy and future direction of the optical flow technique in the physical study of vascular flow.

The Role Of Soil Stiffness In Reverse Fault Rupture Propagation, Moises I. Buelna

Master's Theses

A nonlinear Mohr-Coulomb constitutive model with a strain dependent yield surface and non-associated flow was employed to study the plastic soil properties which affect the rate of surface fault rupture propagation in reverse events. These numerical simulations show a trend for soils with higher stiffness to have a higher rate of rupture propagation. Additionally the study shows the effects of strain softening and hardening on the rate of rupture propagation. Soils which strain harden exhibiting ductile behavior typically require more basal offset to rupture to the surface than soils which strain soften exhibiting brittle behavior. These results agree with our …

Me-Em Enewsbrief, July-December 2017, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

A Comparison Study Of Composite Laminated Plates With Holes Under Tension, Joun S. Kim

Master's Theses

A Comparison Study of Composite Laminated Plates with Holes under Tension

A study was conducted to quantify the accuracy of numerical approximations to deem sufficiency in validating structural composite design, thus minimizing, or even eliminating the need for experimental test. Error values for stress and strain were compared between Finite Element Analysis (FEA) and analytical (Classical Laminated Plate Theory), and FEA and experimental tensile test for two composite plate designs under tension: a cross-ply composite plate design of [(0/90)4]s, and a quasi-isotropic layup design of [02/+45/-45/902]s, each with a single, centered hole of 1/8” diameter, and 1/4" diameter (four sets …

Controlled Electrochemical Reduction Of Gold And Palladium Metal Precursors In Polyaniline, Nicole Goodwin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively studied due to its unique electrochemical properties. The conjugated polymer is conductive with high chemical stability below 100°C, mechanical strength, and large surface area. The applications of PANI have included chemical sensing, corrosion inhibition coatings, light emitting diode and as a substrate for metal composite catalysts. Both chemical and electrochemical methods have been developed and utilized in the synthesis of PANI/metal composites. The simultaneous reduction of aniline and metal precursor produces a composite of PANI encapsulated metal, reducing the active surface area available for catalysis. Alternatively, chemical reduction of the metal precursor into preformed PANI …

Surface And Interface Characterization Of Solution-Processed Metal Oxides And Pedot:Pss Using Photoelectron Spectroscopy, Lynette M. Kogler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solution-processed materials are appealing for use in printable electronics as a means to lower production costs, but precise control of the process is crucial for achieving the desired properties in the final materials and their interfaces. Electronic interface properties depend on both the involved materials and their fabrication processes, impacting the development and commercialization of these materials. Analyzing the chemical and electronic structure of these materials, particularly at the surfaces and interfaces, is important not only for insuring that the materials have the desired properties, but also for understanding the effects of the fabrication process and how to modify properties …

Synthesis Of Magnetic Carbon Supported Manganese Catalysts For Phenol Oxidation By Activation Of Peroxymonosulfate, Yuxian Wang, Yongbing Xie, Chunmao Chen, Xiaoguang Duan, Hongqi Sun, Shaobin Wang

Research outputs 2014 to 2021

Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe₃O₄/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as the precursor of manganese oxide. The Mn/MCS catalysts were characterized by a variety of characterization techniques and the catalytic performances of Fe₃O₄/C/Mn nanoparticles were tested in activation of peroxymonosulfate to produce reactive radicals for phenol degradation in aqueous solutions. It was found that Fe₃O₄/C/Mn catalysts can be well dispersed …

Blanking Clearance And Punch Velocity Effects On The Sheared Edge Characteristic In Micro-Blanking Of Commercially Pure Copper Sheet, Didin Zakariya Lubis, Ichsan Ristiawan

Journal of Mechanical Engineering Science and Technology (JMEST)

This study aims to identify the influences between clearance and punch velocity on the part edge quality of blanked parts. Experiments have been conducted using material copper, punch-die clearance and punch velocity variations. In order to determine the reachable punch-die clearance and punch velocity required for blanking. The quality of the part-edge characteristics shows that higher punch velocity and decreases clearance value can improve the part-edge quality, resulting in smaller burr height and rollover, and a larger shear zone. Furthermore, it could be observed that the part-edge quality improvement when blanking with high punch velocity is much more distinct for …

Formula Of Moulding Sand, Bentonite And Portland Cement To Improve The Quality Of Al-Si Cast Alloy, Andoko Andoko, Poppy Puspitasari, Avita Ayu Permanasari, Didin Zakaria Lubis

Journal of Mechanical Engineering Science and Technology (JMEST)

A binder is any material used to strengthen the bonding of moulding sand grains. The primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. In this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% Portland cement, 4% bentonite + 6% Portland cement, 6% bentonite + 4% Portland cement, and 7% bentonite + 3% Portland cement. Each specimen was measured for its compressive strength, shear strength, tensile strength and permeability. The highest compressive strength was obtained fromthe specimen composed of 6% bentonite+ 4% Portland cement. The highest …

Modeling Of Antenna For Deep Target Hydrocarbon Exploration, Nadeem Nasir, Noorhana Yahya, Hasnah Mohd Zaid, Afza Shafie, Norhisham Hamid

Journal of Mechanical Engineering Science and Technology (JMEST)

Nowadays control source electromagnetic method is used for offshore hydrocarbon exploration. Hydrocarbon detection in sea bed logging (SBL) is a very challenging task for deep target hydrocarbon reservoir. Response of electromagnetic (EM) field from marine environment is very low and it is very difficult to predict deep target reservoir below 2km from the sea floor. This work premise deals with modeling of new antenna for deep water deep target hydrocarbon exploration. Conventional and new EM antennas at 0.125Hz frequency are used in modeling for the detection of deep target hydrocarbon reservoir. The proposed area of the seabed model (40km ´ …