Engineering Commons^™

Influence Of Casting Techniques On Hardness, Tarnish Behavior And Microstructure Of Ag-Cu-Zn-Si Sterling Silver Jewelry Alloys, C. Chanmuang, W. Kongmuang, J.T.H. Pearce, T. Chairuangsri

Journal of Metals, Materials and Minerals

The effects of Zn and Si on the hardness, tarnish resistance and microstructures of experimental Ag-Cu-Zn-Si alloy were investigated by means of vickers hardness, tarnish testing, optical and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The various compositions of 935 sterling silver alloys produced by different casting techniques, investment (lost wax) process and metal mould casting, were compared. An induction casting machine with a vacuum system was used for investment casting at 1,025C with the mould temperature at 600C whereas a LPG/oxygen single flame tip torch was used for the metal mould process. Vickers hardness of the samples …

Ballistic Performance Of Ceramic/S2-Glass Composite Armor, K. Dateraksa, K. Sujirote, R. Mccuiston, D. Atong

Journal of Metals, Materials and Minerals

Ceramic composite armor was initially developed during the Vietnam War for use as helicopter armor and personnel armor. The requirements for the armor were light weight and the capability to defeat small caliber armor piercing (AP) projectiles. Several different ceramics were developed and tested for this application. It was found that aluminum oxide (Al2O3), silicon carbide (SiC) and boron carbide (B4C) had the best combination of properties to meet the requirements. The long term goal of this research is to develop domestic knowledge, design and production capability of ceramic composite armors. In this present research, the relationship between the ballistic …

Bismuth Vanadate (Bivo4) Powder Prepared By The Sol-Gel Method, P. Pookmanee, S. Kojinok, S. Phanichphant

Journal of Metals, Materials and Minerals

Bismuth vanadate (BiVO4) powder was prepared by the sol-gel method. Bismuth nitrate and ammonium vanadate were used as the starting precursors with mole ratio of 1:1 in ethanol at 70C for 1 hour. The obtained sol was changed to the yellow gel after addition of deionized water and acetic acid. The yellow gel was dried at 100C for 48 h and calcined at 400-600C for 2 hours. The phase of BiVO4 powder was studied by X-ray diffraction (XRD). The morphology of BiVO4 powder was investigated by scanning electron microscopy (SEM). The element composition of BiVO4 powder was indicated by energy …

Effect Of Milling Method On The Particle Size Of Calcined 0.65pmn-0.35pt Powder, A. Boonruang, P. Ngernchuklin, C. Eamchotchawalit

Journal of Metals, Materials and Minerals

In this study, stoichiometric 0.65PMN-0.35PT powders have been prepared by columbite method. The perovskite single phase of PMN-PT was successfully synthesized after calcination of the mixed oxide at 900C/4hr. Due to the particle size of calcined powder has greatly effect on the electrical properties of sintered samples. Therefore, two different milling methods including high energy ball milling (HBM) and conventional ball milling (CBM) were used to grind the calcined powders. The results showed that the particle size distribution of calcined powders from HBM and CBM were 0.17 and 0.19 ?m, respectively. As a result, the relative density of the sintered …

Effect Of Zn Addition On Sol-Gel Derived Apatite/Wollastonite Glass-Ceramics Scaffolds, S. Tubsungneon Rattanachan, N. Srakaew, R. Pethnin, N. Suppakarn

Journal of Metals, Materials and Minerals

Bioactive glasses and glass-ceramics consisting of CaO-MgO-P2O5-SiO2 system have been shown to be bioactive, resorbable and to exhibit appropriate mechanical properties for bone tissue engineering applications. Bioactive glass-ceramics scaffolds consisting of zinc doped-apatite/wollastonite (AW) glassceramics were prepared by coating polyurethane foams with sol-gel derived glass gels. Density and compressive strength of the scaffolds decreased with increased in zinc contents. In vitro bioactivity of Zndoped AW glass-ceramics in a simulated body fluid (SBF) showed the formation of apatite layer on the surface within 7 days of soaking. However, increasing Zn addition increased the chemical durability of the AW glass-ceramics, resulting in …

Characterization And Drug Behavior In Shellac Wax Poloxamer Matrix Tablets Fabricated With Mold Technique, C. Choncheewa, T. Phaechamud

Journal of Metals, Materials and Minerals

Shellac wax is a waste product from shellac manufacturing process and has not been reported to be used as pharmaceutical matrix base. This study was to prepared and characterized shellac wax - poloxamer 407 matrix tablet comprising hydrophilic or hydrophobic drug which were prepared by molten technique. The ratios of poloxamer 407: shellac wax was varied and subsequently loaded with the different drug content before characterized with differential scaning calorimetry (DSC), thermogravimetric analysis (TGA) and powder x-ray diffractometry (PXRD). Drug release study was also performed for 25 mg drug loaded matrix tablet in distilled water using dissolution apparatus II at …

Role Of Aluminum Monostearate On Heat Treated-Chitosan Sponges Properties, K. Yodkhum, T. Phaechamud

Journal of Metals, Materials and Minerals

Heat treatment can be employed to modify properties such as biocompatibility and degradation rate of chitosan-based materials. However, heat treatment generally has effect on worsening of physical properties of the biomaterials. Our previous study indicated that fatty additive; aluminum monostearate (Alst), could improve thermal stability of chitosan sponges. Aim of this study is to investigate an effect of amount of Alst on physicochemical properties of chitosan sponges treated by different heat treatment methods. Two methods of heat treatment including moist heat (autoclave at 121°C, 15 psi for 5 minutes) and dry heat (vacuum heat at 110°C for 24 hours) were …

Preparation And Characterization Of Highly Filled Graphite-Based Polybenzoxazine Composites, A. Pengdam, S. Rimdusit

Journal of Metals, Materials and Minerals

This research aims to study suitable preparation methods and to characterize highly filled graphite composites using polybenzoxazine as a matrix. The high loading of graphite filler was attained in the range of 40 to 80% by wt. due to the very low a-stage viscosity of the benzoxazine resin (BA-a) used. The suitable condition for the compression molding of the highly filled graphite-polybenzoxazine (PBA-a) composites was at temperature of 200°C, and pressure of 15 MPa in the hydraulic hot-press machine for 3 hours to assure a fully cured specimen. The densities of the obtained composites were found to be in a …

Effect Of Silicon On Subcritical Heat Treatment Behavior And Wear Resistance Of 16 Wt% Cr Cast Iron With 2 Wt% Mo, P. Kosasu, S. Inthidech, P. Srichareonchai, Y. Matsubara

Journal of Metals, Materials and Minerals

Effects of Si content on the hardness, decomposition of austenite and abrasive wear resistance during subcritical heat treatment of hypoeutectic 16 wt% Cr -2 wt% Mo cast irons were investigated. The hypoeutectic 16 wt%Cr-2wt% Mo cast irons with 0.5-2.0 wt% Si were prepared. The as-cast specimens were heated up to subcritical temperatures at 50 K intervals from 673K for 14.4 ks ,28.8 ks and 43.2 ks and then, cooled to the room temperature by fan air cooling. In the as-cast state, the hardness increased gradually as Si content increased to 1.5 wt% and then decreased rapidly. The size and the …

Twin-Jet Electropolishing Of Cast Sterling Silver Alloys Using Perchloric Acid And Potassium Cyanide Solutions, W. Kongmuang, T. Chairuangsri, C. Chanmuang

Journal of Metals, Materials and Minerals

Twin-jet electropolishing of Ag-4.87 wt%Cu-0.79 wt%Zn-0.09 wt%Si alloy was studied. Two electrolytes, i.e. potassium cyanide solution in distilled water and glycerol-perchloric acid solution in absolute ethanol, were used in the experiments. Effects of parameters including voltage and electrolyte concentration have been studied. Surface of polishing specimens and artifact formed were characterized by light microscopy and electron microscopy. In general, the potassium cyanide solution is a better electrolyte than the glycerol-perchloric acid solution. A more uniform polishing can be obtained from the potassium cyanide solution at the voltage higher than 5 V. Increasing of the potassium cyanide concentration reduced the electrical …

Study Of Dynamic Vulcanized Pla/Enr Tpv Filled With Various Organic Modified Mmt (Ommt), C. Thongpin, N. Kuttanate, K. Kampuang, N. Suwanwanit

Journal of Metals, Materials and Minerals

In this research, we investigated the crystallization behavior of PLA and properties of PLA/ENR thermoplastic vulcanizates (TPVs). ENR was compounded with phenolic resin and with PLA at the blend ratio of 40/60 by using an internal mixer at 170°C and rotor speed of 70 rpm. Three types of organic modified montmorillonite (OMMT) which are Cloisite® 15A, Cloisite® 20 A and Cloisite® 30B were also added at various contents during mixing. The TPVs were pressed to form thin film in a compression molding machine and cooled down under pressure for 10 minutes. Crystallization behavior, thermal properties and morphology of TPVs were …

Preparation And Catalytic Property Of High Surface Area Mixed Oxides From Calcination Of Mgcucr- And Mgcual-Layered Double Hydroxides, W. Trakarnpruk

Journal of Metals, Materials and Minerals

In this research work layered double hydroxides (LDHs) containing Mg, Cu and Cr(or Al) were prepared with starting Mg:Cu:Cr (or Al) molar ratio of 2:1:1. They were calcined at 500 ºC for 5 h to convert into corresponding mixed oxides possessing high surface area. The catalysts were characterized by chemical analysis (ICP), infrared spectroscopy (FTIR), thermal analysis (TGA/DTA), powder X-ray diffraction (XRD), surface area measurements and H2 temperature programmed reduction (TPR). Catalytic property of these mixed oxides catalysts were tested in the oxidation of ethylbenzene using tertbutylhydroperoxide as an oxidant without added solvent. The experimental results show that high conversion …

Adaptive Local And Global Synchronization And Phase Control Of Inferior Olive Neurons (Ions), Srujan Kumar Chalike

UNLV Theses, Dissertations, Professional Papers, and Capstones

Clusters of inferior olive neurons (IONs) in the olive-cerebellar system play an important role in providing synchronized motor control signals for the activation of large number of muscles. However, the dynamics of IONs are highly nonlinear and the system parameters are assumed to be unknowm. The IONs evolving from arbitrary initial conditions are not synchronized. However the application of IONs for control of BAUV's requires that IONs oscillate in unison. The objective is to design control laws such that the controlled ION tracks the trajectories of the reference ION. The two control laws are derived based on tuning functions adaptive …

Mobile First Web And Content Strategy, Stefanie Havelka, David Stevens

Publications and Research

The paradigm shift from the traditional desktop to the mobile web experience is fast approaching, and providing relevant date, location and time-sensitive content to users via mobile devices becomes an essential piece of the overall web strategy. This presentation demonstrates the concepts, techniques and technologies used to develop both the overall mobile content strategy and user experience, as well as the aggregation and delivery of content to both the desktop and mobile form factors from a single content source.

Stable Fluorinated Antimicrobial Coatings, Asima Chakravorty

Theses and Dissertations

Contact antimicrobials for use in the medical device industry are being studied extensively to minimize the risk of hospital acquired infections, which are among the top ten leading causes of death in the US. Surfaces modified with quaternary ammonium containing side chains have been known to demonstrate excellent antimicrobial properties. Prior work has indicated that polyurethane surfaces with copolyoxetane soft blocks consisting of fluorinated and quaternary ammonium side chains can act as good antimicrobials. However, stabilizing the positive charge on the surface has been a challenge. The dissertation is aimed at creating a surface modifier that would confer a stable …

Cable Median Barrier Failure Analysis And Remediation, Cody S.. Stolle

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

On divided roadways, cross-median fatalities are disproportionately overrepresented in fatal and serious injury crashes. Many state DOTs sought to mitigate cross-median crash risk by installing cable median barriers. Despite increased crash rates, studies evaluating crash rates before and after cable median barriers were installed indicated excellent improvement in overall safety.

Although cable median barriers are intended to prevent serious cross-median crashes, cable barriers can also contribute to serious injury and fatality crashes which would not have otherwise occurred, including penetration and rollover crashes. In order to reduce the frequency of undesirable penetration and rollover crashes occurring with cable median barriers …

Predicting Vehicle Dynamics For Roadside Safety Using Multibody Systems Simulations, Brett D. Schlueter

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Accurate means for predicting vehicle dynamics is required in the design and testing of roadside safety hardware. Past research has used finite element (FE) modeling to this end, but multibody systems (MBS) modeling may provide a more efficient way to solve these problems. MBS modeling using Adams/Car was investigated by first compiling an introduction to the program, then performing basic vehicle dynamics simulations using a supplied model. Next, a model of a 2270 kg pickup was created and validated against physical test data involving impact with a speed bump. Finally, pickup trajectories in 4H:1V and 6H:1V V-ditches were predicted for …

Modular Joystick Design For Virtual Reality Surgical Skills Training, Michael Head

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

A modular control interface and simulated virtual reality environment was designed and created in order to determine how the kinematic architecture of a control interface affects minimally invasive surgery. A user is able to selectively determine how many, the type, and location of degrees of freedom they require for the specific surgical simulation through the use of modular joints and constraint components. Furthermore, passive locking was designed and implemented through the use of inflated latex tubing around rotational degree of freedom joints. It is believed these features will have the ability to effectively simulate a variety of surgical simulations and …

Filtering Techniques For Pose Estimation With Applications To Unmanned Air Vehicles, Bryce Benson Ready

Theses and Dissertations

This work presents two novel methods of estimating the state of a dynamic system in a Kalman Filtering framework. The first is an application specific method for use with systems performing Visual Odometry in a mostly planar scene. Because a Visual Odometry method inherently provides relative information about the pose of a platform, we use this system as part of the time update in a Kalman Filtering framework, and develop a novel way to propagate the uncertainty of the pose through this time update method. Our initial results show that this method is able to reduce localization error significantly with …

Improving Rapid Prototyping Through The Installment Of 3d Printers In Automotive Companies, Kelly Mccarthy

Honors Theses

Three-dimensional (3D) printing is a relatively new form of additive manufacturing that has the potential to induce a second industrial revolution. This technology utilizes a print head to lay down raw materials in successive layers to fabricate a three dimensional object. There are several techniques in 3D printing, two of which will be discussed hi this proposal: fused deposition modeling (FDM), and inkjet/polyjet matrix 3D printing.

Although this technology has been around since the 1980s, it is constantly evolving and new materials, uses, and objects are created daily. This technology presents the potential to manufacture a variety of objects across …

Development Of A Closed-Loop Force Reduction Mechanism In A Gait Rehabilitation Device, Jeffrey Frankart

Theses and Dissertations

Elliptical trainers are prescribed in rehabilitative exercise but difficult to implement in populations with significant functional gait deficits. Typical elliptical machines do not mimic normal gait and therefore require modifications for clinical rehabilitation. This research builds on previous modifications of an elliptical trainer designed to simulate level-surface walking. This design differed from a commercial version. It included articulated footplates and an electromechanically-driven virtual-cam to control footplate position. Ankle dorsiflexion elicited lower-extremity muscle spasticity which produced an unwanted gait variant during stroke patient testing. Spasticity is a hyperexcitable stretch reflex causing inefficient gait. This project’s purpose was to develop an autonomous …

A New Approach To Safety Assessment At Gated Highway–Rail Grade Crossings, Zheng Luo

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

A significant number of pedestrians and bicyclists (i.e., non-motorists) use the roadway system in the U.S. Research pertaining to the safety of them, especially their safety at highway-rail grade crossings (HRGCs), has drawn much attention in the past decade, and remains an important issue of safety research. Yet, the majority of existing research has examined non-motorist safety at intersections or motorist safety at HRGCs separately. Such research has related primarily to exploring relationships between safety countermeasures (e.g., engineering devices, education, enforcement, etc.) and crash frequency/severity, using different quantitative analysis approaches. A primary limitation of these studies is that few have …

Novel Shear-Thinning Of Aged Pdms/Fumed Silica Admixtures And Properties Of Related Silicone Elastomers, Wayne Brooke-Devlin

Theses and Dissertations

Fumed silica filler has long been used to structurally reinforce silicone elastomers. Unfortunately, the combination of as little as a few weight percent of untreated fumed silica nanoparticles [uFSN] with a siloxane polymer, such as PDMS, forms a difficult to process waxy solid admixture that even long periods of high shear mixing will not thin. In the course of the current work it was noted that after a period of storage certain solid admixtures would become viscous liquids when subjected to additional high shear mixing. It was further found that the required aging period could be decreased if the admixture …

Safety Effectiveness Of Red Light Treatments For Red Light Running, Carl Scott Olson

Dissertations and Theses

Crashes resulting from automobiles running a red light are typically severe in nature. One way to try to reduce the number and severity of these types of crashes is by increasing the red clearance interval of a traffic signal. In Portland, Oregon, eight intersections received a variety of treatments including red extensions. Determining which treatment had what effect can be difficult to weed out. Using a combination of crash analysis and a model simulating an intersection with red extensions, this paper describes the estimated impact of red light running intersection upgrades and red extensions on crashes. By performing a variety …

Addressing The Need To Reform Construction Public Procurement In Ireland Through The Implementation Of Building Information Modelling, Barry Mcauley, Alan Hore, Roger West, Dermot Kehily

Conference papers

The Irish AEC Sector is facing one of its most uncertain and challenging periods and will see major cuts in all areas of the economy in 2012. Despite this the Irish Government has announced a number of large capital expenditure investments which have resultantly become a lifeline to a struggling construction industry. In order to compete within the public works sector AEC businesses must operate within the Governments Capital Works Management Framework. The objectives of the framework include achieving cost certainty, value for money and more effective delivery and appropriate risk sharing. The framework remains an area of contention and …

Site-Specific Metallization Of Multiple Metals On A Single Dna Origami Template, Bibek Uprety

Theses and Dissertations

This work examines the selective deposition of two different metals on the same DNA origami template for nanofabrication. DNA, with adjustable size and shape serves as a suitable template for fabricating metal junctions in the nanometer domain via bottom-up assembly. Bottom-up assembly utilizes the recognition capability of molecules like DNA to self-assemble and form structures. In this regard, DNA origami provides a useful means for forming nanostructures by folding single-stranded DNA into different two and three dimensional shapes. Selective deposition of metal on specific locations of a DNA template is essential for making DNA-templated electronic circuits.Site-specific metallization of DNA origami …

An Optimization-Based Method Of Traversing Dynamic S-Pareto Frontiers, Patrick K. Lewis

Theses and Dissertations

The use of multiobjective optimization in identifying systems that account for changes in customer needs, operating environments, system design concepts, and analysis models over time is generally not explored. Providing solutions that anticipate, account for, and allow for these changes over time is a significant challenge to manufacturers and design engineers. Products that adapt to these changes through the addition and/or subtraction of modules can reduce production costs through product commonality, and cater to customization and adaptation. In terms of identifying sets of non-dominated designs, these changes result in the concept of dynamic Pareto frontiers, or dynamic s-Pareto frontiers …

Compression Transmission Collar For Fastening, David Lecronier, Patrick Atkinson

Mechanical Engineering Patents

A compression transmission collar apparatus for implantation into a bone with a hole having a hole wall comprising an intramedullary nail defining a bore and a threaded fastener and a compression transmission collar including an exterior face and a top edge and a bottom edge and a first end interstcting the top edge at an acute angle and the bottom edge at an obtuse angle and a second end intersecting the top edge at an obtuse angle and the bottom edge at an acute angle and the first end partially overlapping and opposing the second end to define a slit …

Compression Transmission Collar For Fastening, Patrick Atkinson

Mechanical Engineering Patents

A compression transmission collar apparatus (20) for implantation into a bone (22) with a hole (28) having a hole wall (32) comprising an intramedullary nail (34) defining a bore (40) and a threaded fastener (42) and a compression transmission collar (58) including an exterior face (64) and a top edge (60) and a bottom edge (62) and a first end (70) intersecting the top edge (60) at an acute angle (α₁) and …

Measurement Of Thermal Diffusivities Using The Distributed Source, Finite Absorption Model, James B. Hall

Theses and Dissertations

Thermal diffusivity in an important thermophysical property that quantifies the ratio of the rate at which heat is conducted through a material to the amount of energy stored in a material. The pulsed laser diffusion (PLD) method is a widely used technique for measuring thermal diffusivities of materials. This technique is based on the fact that the diffusivity of a sample may be inferred from measurement of the time-dependent temperature profile at a point on the surface of a sample that has been exposed to a pulse of radiant energy from a laser or flash lamp. An accepted standard approach …