Leaching Of A Mongolian Chalcopyrite Concentrate,
2018
Edith Cowan University
Leaching Of A Mongolian Chalcopyrite Concentrate, Nicholas J. Welham, Jadambaa Temuujin, Nader Setoudeh
Research outputs 2014 to 2021
A Mongolian chalcopyrite flotation concentrate was leached using sodium hypochlorite adjusted to different pH using hydrochloric acid. It was found that using a starting pH of below 5.0 resulted in more efficient leaching. The extent of chalcopyrite leaching was determined by the concentration of sodium hypochlorite with > 40% dissolution being achieved. The residue after leaching was found to consist primarily of unreacted chalcopyrite which would be suitable for further leaching or smelting.
Implementation Of Magnesium Alloy Az91d On Wire And Arc Additive Manufacturing,
2018
University of Texas at El Paso
Implementation Of Magnesium Alloy Az91d On Wire And Arc Additive Manufacturing, David Adrian Martinez Holguin
Open Access Theses & Dissertations
As progress on Additive Manufacturing (AM) techniques focusing on ceramics and polymers evolve, metals continue to be a challenging material to manipulate when fabricating products. Current methods, such as Selective Laser Sintering (SLS) and Electron Beam Melting (EBM) face many intrinsic limitations due to the nature of their processes. Material selection, elevated cost and low deposition rates are some of the barriers to consider when one of these methods is to be used for the fabrication of engineering products. The research here presented demonstrates the use of a Wire and Arc Additive Manufacturing (WAAM) system for the creation of metallic …
การประมาณค่าในช่วงเชิงพหุนามลากรานจ์ร่วมกับตัวประกอบถ่วงน้ำหนักนอกช่วงแบบใหม่เพื่อแก้ปัญหาการไหลภายในช่องว่างสี่เหลี่ยมผืนผ้า,
2018
คณะวิศวกรรมศาสตร์
การประมาณค่าในช่วงเชิงพหุนามลากรานจ์ร่วมกับตัวประกอบถ่วงน้ำหนักนอกช่วงแบบใหม่เพื่อแก้ปัญหาการไหลภายในช่องว่างสี่เหลี่ยมผืนผ้า, อุทัย ประสพชิงชนะ
Chulalongkorn University Theses and Dissertations (Chula ETD)
งานวิจัยนี้มีวัตถุประสงค์เพื่อนำเสนอแผนแบบใหม่ที่มีชื่อว่าแผนแบบ LIP (Lagrange Interpolating Polynomial scheme) และการประมาณค่านอกช่วงแบบใหม่ที่มีชื่อว่าการประมาณค่านอกช่วงแบบ WF-LIP (Weighting Factors with Lagrange Interpolating Polynomial extrapolation) โดยแผนแบบ LIP ถูกใช้สำหรับการประมาณค่าของตัวแปรและอนุพันธ์ของตัวแปรทั้งเทียบกับระยะและเวลาในระเบียบวิธีไฟไนต์วอลู่ม ข้อดีของแผนแบบ LIP คือ เป็นแผนที่มีความแม่นยำลำดับสี่ เป็นแผนที่ง่ายต่อการพัฒนาโปรแกรมที่ใช้การแก้ปัญหาด้วยเม็สซ์ที่ไม่สม่ำเสมอ และเป็นทั้งแผนทางระยะและแผนทางเวลา สำหรับการประมาณค่านอกช่วงแบบ WF-LIP ถูกนำมาใช้ในการหาค่าคาดเดาเริ่มต้นของตัวแปรในแต่ละช่วงเวลาย่อยของปัญหาที่สภาวะไม่คงตัว ซึ่งใช้วิธีการหาคำตอบของแต่ละช่วงเวลาย่อยด้วยวิธีการทำซ้ำ จากผลการตรวจสอบความถูกต้องของคำตอบที่คำนวณจากแผนแบบ LIP และการทดสอบประสิทธิภาพของการประมาณค่านอกช่วงแบบ WF-LIP พบว่า คำตอบที่คำนวณจากแผนแบบ LIP มีความถูกต้องและมีความสอดคล้องกับคำตอบที่นำมาใช้ในการเปรียบเทียบความถูกต้อง ขณะที่การประมาณค่านอกช่วงแบบ WF-LIP สามารถช่วยลดระยะเวลาที่ใช้ในการคำนวณเพื่อหาคำตอบของปัญหาได้สูงสุดถึงร้อยละ 49.69 เมื่อเทียบกับกรณีที่การคำนวณหาคำตอบ โดยไม่ได้ใช้การประมาณค่านอกช่วงแบบ WF-LIP
Development And Characterization Of Novel Materials For The Advancement Of Additive Manufacturing By Material Extrusion 3d Printing,
2018
University of Texas at El Paso
Development And Characterization Of Novel Materials For The Advancement Of Additive Manufacturing By Material Extrusion 3d Printing, Jose Gilberto Siqueiros
Open Access Theses & Dissertations
The development of additive manufacturing technologies has been under the spotlight from the past decade due to its enormous potential to disrupt current manufacturing processes. Material extrusion 3D printing (ME3DP) is the most common type of additive manufacturing technology as it experienced an exponential growth after the expiration of the fused deposition modeling patent filed in 1989 by Scott Crump. The large interest behind this technology is generated from the capacity to create complex shapes, rapid prototyping, relatively ease of use, low cost, and high accessibility. The gradual evolution of material extrusion 3D printing calls to become a technology ordinarily …
Microstructural Characterization Of LensTm Ti-6al-4v: Investigating The Effects Of Process Variables Across Multiple Deposit Geometries,
2018
Wright State University
Microstructural Characterization Of LensTm Ti-6al-4v: Investigating The Effects Of Process Variables Across Multiple Deposit Geometries, Laura Christine Davidson
Browse all Theses and Dissertations
Laser based additive manufacturing of Ti-6Al-4V components is under consideration for aerospace applications. The mechanical properties of the finished components depend on their microstructure. Process mapping compares process variables such as heat source power, heat source travel speed, material feed rate, part preheat temperature and feature geometry to process outcomes such as microstructure, melt pool geometry and residual stresses. In this work, the microstructure of two-dimensional pads, multilayer pads, thin walls, and structural components at the steady state location was observed. A method for measuring β grain widths that allows for the calculation of standard deviations, confidence intervals, and variances …
Galvanic And Pitting Corrosion Of A Fastener Assembly,
2018
The University of Akron
Galvanic And Pitting Corrosion Of A Fastener Assembly, Julie Shallman
Williams Honors College, Honors Research Projects
This research focuses on coupled galvanic/pitting corrosion of AA7075 when combined with stainless steel in a fastener assembly. A one-dimensional mathematical model of a well-mixed thin film electrolyte is developed to predict the damage profile of the AA7075 surface when its protective coating is damaged. The damage exposes the galvanic couple. A time dependent system of partial differential equations for potential, chloride concentration, aluminum ion concentration, and damage is developed and solved numerically. Two approaches to calculate the current density within aluminum pits are discussed. The first is a current balance between the cathodic, anodic and passive portions of the …
Defect Engineering: Novel Strengthening Mechanism For Low- Dimensional Zinc Oxide Nanostructures,
2018
Wright State University
Defect Engineering: Novel Strengthening Mechanism For Low- Dimensional Zinc Oxide Nanostructures, Seyed Emad Rezaei
Browse all Theses and Dissertations
The advent of nanomaterials has opened a new avenue for designing and fabricating materials with unique properties, e.g., superior mechanical properties. Based on a common notion, the perfect structures are assumed to exhibit better mechanical properties, such as higher yield strength and Young's modulus. Therefore, researchers have devoted an extensive amount of time to decrease defect concentration by fabricating materials with the micro/nanoscale, e.g., nanowires (NWs) and nanobelts (NBs), to enhance the mechanical characteristics of the system. However, defects are a part of the fabrication process and precise control over synthesizing procedure is needed to eliminate them from the material. …
Functionalization And Characterization Of Chemical Vapor Deposited Graphene Sheets Towards Application In Chemical Vapor Sensing,
2018
Wright State University
Functionalization And Characterization Of Chemical Vapor Deposited Graphene Sheets Towards Application In Chemical Vapor Sensing, Nicholas Alexander Engel
Browse all Theses and Dissertations
Chemical/biological sensors serve many purposes in protecting machinery, the environment, and human life/wellness. Graphene, a two-dimensional (2-D) material made up of carbon atoms in a honeycomb-like lattice, is promising for applications to chemical/biological sensing due to its unique properties. Functionalization of graphene by surface decorating with nanoparticles and increasing interior adsorption sites can tailor its catalytic activity and electrical properties, and hence, important for detecting and distinguishing trace hazardous gases. This research introduces two different approaches to functionalize graphene towards enhanced sensitivity and selectivity of graphene-based sensors. The morphologies, structures, and electrical properties of the functionalized graphene are systematically characterized. …
Magneto-Optical Properties Of Thin Permalloy Films: A Study Of The Magneto-Optical Generation Of Light Carrying Angular Momentum,
2018
University of Kentucky
Magneto-Optical Properties Of Thin Permalloy Films: A Study Of The Magneto-Optical Generation Of Light Carrying Angular Momentum, Patrick D. Montgomery
Theses and Dissertations--Electrical and Computer Engineering
Magneto-optical materials such as permalloy can be used to create artificial spin- ice (ASI) lattices with antiferromagnetic ordering. Magneto-optical materials used to create diffraction lattices are known to exhibit magnetic scattering at the half- order Bragg peak while in the ground state. The significant drawbacks of studying the magneto-optical generation of OAM using x-rays are cost, time, and access to proper equipment. In this work, it is shown that the possibility of studying OAM and magneto-optical materials in the spectrum of visible light at or around 2 eV is viable. Using spectroscopic ellipsometry it is possible to detect a change …
Flow Patterns Through Vascular Graft Models With And Without Cuffs,
2018
Rensselaer Polytechnic Institute
Flow Patterns Through Vascular Graft Models With And Without Cuffs, Chia Min Leong, Gary B. Nackman, Timothy Wei
Department of Mechanical and Materials Engineering: Faculty Publications
The shape of a bypass graft plays an important role on its efficacy. Here, we investigated flow through two vascular graft designs±with and without cuff at the anastomosis. We conducted Digital Particle Image Velocimetry (DPIV) measurements to obtain the flow field information through these vascular grafts. Two pulsatile flow waveforms corresponding to cardiac cycles during the rest and the excitation states, with 10% and without retrograde flow out the proximal end of the native artery were examined. In the absence of retrograde flow, the straight end-to-side graft showed recirculation and stagnation regions that lasted throughout the full cardiac cycle with …
Dislocations Interaction Induced Structural Instability In
Intermetallic Al2cu,
2018
Xi'an Jiaotong University
Dislocations Interaction Induced Structural Instability In Intermetallic Al2cu, Qing Zhou, Jian Wang, Amit Misra, Ping Huang, Fei Wang, Kewei Xu
Department of Mechanical and Materials Engineering: Faculty Publications
Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic deformation. Using atomistic simulations, we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al2Cu. Interaction of non-coplanar <001> dislocation dipoles during plastic deformation results in anomalous reactions—the creation of vacancies accompanied with climb and collective glide of <001> dislocation associated with the dislocation core change and atomic shuffle—accounting for structural instability in intermetallic Al2Cu. This process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be …
Mechanical Performance Of Plla Stent,
2018
University of Nebraska-Lincoln
Mechanical Performance Of Plla Stent, Longzhen Wang, Junfei Tong, Pengfei Dong, David L. Wilson, Hiram G. Bezerra, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
Stent implantation is widely used to treat blocked lumen. Stents were meshed structure made of polymers and metal alloys, including stainless steel, cobalt chrome and nitinol [1]. Clinical studies had demonstrated that stents helped to scaffold the diseased lesion up to one year when tissue adapted to the stented environment [2]. However, the permanently implanted stents inside artery were associated with complications such as stent fracture, tissue inflammation, in-stent restenosis and thrombosis [3]. Currently, biodegradable stents are attracting more attention due to its potential long-term efficacy in treating blocked lumens. The detailed characterizations of biodegradable stents are essential for the …
Plaque Burden Influences Accurate Classification Of Fibrous Cap Atheroma
By In-Vivo Optical Coherence Tomography In A Porcine Model Of Advanced
Coronary Atherosclerosis.,
2018
Aarhus University Hospital
Plaque Burden Influences Accurate Classification Of Fibrous Cap Atheroma By In-Vivo Optical Coherence Tomography In A Porcine Model Of Advanced Coronary Atherosclerosis., Christian B. Poulsen, Ryan M. Pedrigi, Nilesh Pareek, Ismail D. Kilic, Niels R. Holm, Jacob F. Bentzon, Hans Erik Botker, Erling Falk, Rob Krams, Ranil De Silva
Department of Mechanical and Materials Engineering: Faculty Publications
Advanced coronary atherosclerosis assessed by in-vivo optical coherence tomography (OCT) has not been directly compared with histology. In a porcine model with human-like coronary atherosclerosis we compared in-vivo OCT images with histology in five animals. We found a high sensitivity but modest specificity of OCT in classifying fibrous cap atheroma (FCA). The modest specificity was caused by misclassification of FCA lesions as pathological intimal thickening. The misclassification most frequently occurred when plaque burden exceeded ~20%. Compared with histology, OCT has high sensitivity but modest specificity for identifying FCA. The study suggests that plaque burden should be considered when interpreting OCT …
Multifunctional Operational
Component For Robotic Devices,
2018
University of Nebraska-Lincoln
Multifunctional Operational Component For Robotic Devices, Shane M. Farritor, Amy Lehman, Mark Rentschler
Department of Mechanical and Materials Engineering: Faculty Publications
The various embodiments disclosed herein relate to modular medical devices, including various devices with detachable modular components and various devices with pivotally attached modular components. Additional embodiments relate to procedures in which various of the devices are used cooperatively. Certain embodiments of the medical devices are robotic in vivo devices.
Scaffold Structural Microenvironmental Cues To
Guide Tissue Regeneration In Bone
Tissue Applications,
2018
Sichuan University
Scaffold Structural Microenvironmental Cues To Guide Tissue Regeneration In Bone Tissue Applications, Xuening Chen, Hongyuan Fan, Xiaowei Deng, Lina Wu, Tao Yi, Linxia Gu, Changchun Zhou, Yujiang Fan, Xingdong Zhang
Department of Mechanical and Materials Engineering: Faculty Publications
In the process of bone regeneration, new bone formation is largely affected by physico-chemical cues in the surrounding microenvironment. Tissue cells reside in a complex scaffold physiological microenvironment. The scaffold should provide certain circumstance full of structural cues to enhance multipotent mesenchymal stem cell (MSC) differentiation, osteoblast growth, extracellular matrix (ECM) deposition, and subsequent new bone formation. This article reviewed advances in fabrication technology that enable the creation of biomaterials with well-defined pore structure and surface topography, which can be sensed by host tissue cells (esp., stem cells) and subsequently determine cell fates during differentiation. Three important cues, including scaffold …
Heat Transfer Across A Nanoscale
Pressurized Air Gap And Its
Application In Magnetic Recording,
2018
University of Nebraska-Lincoln
Heat Transfer Across A Nanoscale Pressurized Air Gap And Its Application In Magnetic Recording, Jinglin Zheng, Yung-Kan Chen, Qin Zhou
Department of Mechanical and Materials Engineering: Faculty Publications
In this study, we investigated how a thermally actuated air bearing slider heats up a fast-spinning storage disk through a highly pressurized nanoscale air gap in a magnetic recording system. A Euleriandescription- based computational approach is developed considering heat conduction through a pressurized air film and near-field radiation across the gap. A set of field equations that govern the air bearing dynamics, slider thermo-mechanics and disk heat dissipation are solved simultaneously through an iterative approach. A temperature field on the same order as the hot slider surface itself is found to be established in the disk. The effective local heat …
Interfacial Characterization By Pull-Out Test Of
Bamboo Fibers Embedded In Poly(Lactic Acid),
2018
Groupe de Physique des Matériaux
Interfacial Characterization By Pull-Out Test Of Bamboo Fibers Embedded In Poly(Lactic Acid), Quentin Viel, Antonella Esposito, Jean-Marc Saiter, Carlo Santulli, Joseph A. Turner
Department of Mechanical and Materials Engineering: Faculty Publications
In this work, the apparent shear strength at the interface between a bamboo fiber and the surrounding poly(lactic acid) (PLA) matrix is quantified. A method for processing pull-out test samples within a controlled embedded length is proposed and the details of the test procedure are presented, along with a critical discussion of the results. Two series of samples are considered: untreated and mercerized bamboo fibers from the same batch, embedded in the same polyester matrix. Electron and optical microscopy are used to observe the fiber–matrix interface before and after the test, and to identify the failure mode of each sample, …
Complementary Microscopy Techniques Applied For Characterizing The Localized Nanoscale Structure Of Poly (Vinylidene Fluoride),
2018
University of Nebraska-Lincoln
Complementary Microscopy Techniques Applied For Characterizing The Localized Nanoscale Structure Of Poly (Vinylidene Fluoride), Wen Qian, Shuo Sun, Charles Nguyen, Wenlong Li, Stephen Ducharme, Joesph A. Turner
Department of Mechanical and Materials Engineering: Faculty Publications
Poly (vinylidenefluoride) (PVDF), a well-recognized electroactive polymer, has been studied extensively over many decades. Recently, there has been increasing interest in tuning the electrical properties of PVDF from ferroelectric to piezoelectric and to pyroelectric, which can be attained via controlling the microscale structure down to the nanoscale structure [1-2]. To optimize the preparation conditions of PVDF and its copolymers, as well as to improve the performance for many applications, comprehensive analytical techniques are of great importance. In this paper, we demonstrate complementary nanoscale characterization and measurement techniques, by conducting a systematic and coordinated study involving scanning electron microscopy (SEM), high …
Improved A-B10C2+XHY/Si P-N Heterojunction Performance After Neutron Irradiation,
2018
University of Nebraska-Lincoln
Improved A-B10C2+XHY/Si P-N Heterojunction Performance After Neutron Irradiation, George Peterson, Qing Su, Yongqiang Wang, Natale J. Ianno, Peter Dowben, Michael Nastasi
Department of Mechanical and Materials Engineering: Faculty Publications
The impact of neutron irradiation, in the energy range of ~0.025 eV, on amorphous semiconducting partially dehydrogenated boron carbide (a-B10C2+xHy) on silicon p-n heterojunction diodes was investigated. The heterojunction devices were created by synthesizing a-B10C2+xHy via plasma enhanced chemical vapor deposition on n-type silicon. Unlike many electronic devices, the performance of the a-B10C2+xHy heterojunction diode improved with neutron irradiation, in spite of the large neutron cross section of 10B. There is also increased charge carrier lifetime of more than …
Tissue Stresses In Stented Coronary Arteries With Different Geometries: Effect Of The Relation Between Stent Length And Lesion Length,
2018
Jiangsu University
Tissue Stresses In Stented Coronary Arteries With Different Geometries: Effect Of The Relation Between Stent Length And Lesion Length, Xiang Shen, Song Ji, Yong-Quan Deng, Hong-Fei Zhu, Jia-Bao Jiang, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
In-stent restenosis after stent deployment remains an obstruction in the long-term benefits of stenting. This study sought to investigate the influence of the relation between stent length and lesion length on the mechanics of the arterial wall with different geometries, including straight and tapered vessels. Results showed that when the length of the stent was longer than the lesion length, the maximum stress in plaque and vessel increased as the length of stent increased. When the length of the stent was shorter than the lesion length, the vessel stress induced by stent inflation was lower; both ends of the stenosis …
