Engineering Commons^™

Dynamic Properties Of Railway Track And Its Components : A State-Of-The-Art Review, Sakdirat Kaewunruen, Alexander Remennikov

Faculty of Engineering - Papers (Archive)

Recent findings indicate one of major causes of damages, which is attributed to the resonant behaviours, in a railway track and its components. Basically, when a railway track is excited to generalised dynamic loading, the railway track deforms and then vibrates for certain duration. Dynamic responses of the railway track and its components are the key to evaluate the structural capacity of railway track and its components. If a dynamic loading resonates the railway track’s dynamic responses, its components tend to have the significant damage from excessive dynamic stresses. For example, a rail vibration could lead to defects in rails …

Synthesis And Characterization Of Polymer Brushes For Controlled Adsorption Of Proteins, Olha Hoy

All Dissertations

Performance of biomedical devices to a large extent depends on the interactions between the device surface and the biological liquids/protein molecules. To achieve controllable interactions between the device and biomolecules and still retain the required mechanical strength on the whole, modification of the surface is often done.
In the present study surface properties were modified through a polymer brush approach. After the modification, surfaces gain tunability toward protein adsorption. Mixed polymer brushes consisting of protein repelling and protein attractive components were used, with a 'grafting to' method employed for the synthesis of polymer layers. First, poly(ethylene glycol), the protein repelling …

Nondestructive Evaluation Of Aircraft Composites Using Terahertz Time Domain Spectroscopy, Christopher D. Stoik

Theses and Dissertations

Terahertz (THz) time domain spectroscopy (TDS) was assessed as a nondestructive evaluation technique for aircraft composites. Material properties of glass fiber composite were measured using both transmission and reflection configuration. The interaction of THz with a glass fiber composite was then analyzed, including the effects of scattering, absorption, and the index of refraction, as well as effective medium approximations. THz TDS, in both transmission and reflection configuration, was used to study composite damage, including voids, delaminations, mechanical damage, and heat damage. Measurement of the material properties on samples with localized heat damage showed that burning did not change the refractive …

Nanostructured Chitosan Membranes For Filtration, Keyur Desai

Doctoral Dissertations

Chitosan is a non-toxic and biodegradable biopolymer derived from naturally occurring chitin. It has excellent metal binding and anti-microbial properties which could be beneficial in air and water filtration applications. Nanofibers have distinctly high surface area to volume ratio.

Electrospinning is a process by which nano-sized polymer fibers can be produced using an electrostatically driven jet of polymer solution. The fibers are collected as a non-woven mat and offer a high surface area to volume ratio.

Electrospinning of pure chitosan is hindered by its limited solubility in aqueous acids and high molecular weight with high degree of inter and intra …

A Study Of The Indentation Size Effect In Copper, Jeremy Harper Strader

Doctoral Dissertations

A simple model for an expanding array of screw dislocations is developed to evaluate the size of the containment zone of the geometrically necessary dislocations as it relates to the indentation size effect. The model as developed predicts the same functional form as the Nix-Gao model, H²=H₀²(1+h^*/h), but a new relation for h^* applies that depends only on the Burgers vector and the Taylor constant, where as the Nix-Gao model predicts a strong dependence of the macroscopic hardness and the tip angle. The continuous stiffness method, CSM, is critically examined using experimental …

Mechanical Behavior Of A Ni-Based Crystalline And A Zr-Based Amorphous Materials Subjected To Surface Severe Plastic Deformation, Jiawan Tian

Doctoral Dissertations

A surface-treatment process, surface-severe-plastic deformation (S²PD), is developed and applied on both crystalline and amorphous materials to introduce the plastic deformation in the near-surface layer. A S²PD-processed crystalline component is expected to have enhanced fatigue properties because the refined grains in the near-surface layer and the coarse grains in the interior have good resistance to the crack initiation and propagation, respectively.

The near-surface structures of the processed specimens were characterized by means of the optical microscopy, scanning-electron microscopy (SEM), X-ray diffraction (XRD), and transmission-electron microscopy (TEM). Mechanical properties, such as the microhardness, yield strength, and four-point-bend …

Localized Corrosion Behavior Of Zr-Based Bulk Metallic Glasses In Neutral Nacl Electrolytes, Brandice Annette Green

Doctoral Dissertations

The electrochemical behaviors the Zr₅₀Cu₄₀Al₁₀, Zr₅₀Cu₃₃Al₁₀Pd₇, and Zr_52.5Cu_17.9Al₁₀Ni_14.6Ti_5.0 BMGs were investigated in NaCl solutions. Both Zr₅₀Cu₄₀Al₁₀ and Zr₅₀Cu₃₃Al₁₀Pd₇ exhibited poor corrosion behaviors. Zr₅₀Cu₄₀Al₁₀ was vulnerable to localized corrosion at the open-circuit conditions (OCC). Zr₅₀Cu₃₃Al₁₀Pd₇ experienced localized corrosion at OCC or at slightly higher potentials. Anodic-polarization of both alloys demonstrated that small increases in …

Magnetic Field Effects On Photocurrent And Photovoltaic Processes In Organic Solar Cells, Zhihua Xu

Doctoral Dissertations

Two mechanisms were investigated to understand the magnetic field effects on photocurrent (MFP), a phenomenon whereby an external magnetic field (MF) can increase or decrease photocurrent in organic solar cells (OSCs). The first one relates to MF-modulated intersystem crossing (ISC) between singlet and triplet polaron pairs and charge transfer (CT) complexes, accounting for the positive MFP in low and high magnetic field, respectively. The second mechanism originates from the interaction between triplet excited states and charge carriers, namely triplet-charge reaction (TCR). External magnetic field was found to reduce the rate constant of TCR, leading to negative MFP.

MFP measurements were …

Deformation And Fatigue Behavior Of Bulk-Metallic Glasses (Bmgs), Dongchun Qiao

Doctoral Dissertations

The objectives of the thesis research are 1) to study the strain rate effect on the deformation behavior of bulk-metallic glasses (BMGs), 2) to investigate the loading mode effect on the fatigue behavior of BMGs.

The main results are obtained as follows. At room temperature, during the inhomogeneous deformation, BMGs show the strain softening caused by the increase of the free volume in the shear bands. However, BMGs have a high-energy state and trend to crystallize, especially in the shear bands with the maximum shear stress and the increasing temperature. The instability of BMGs makes it possible for strain hardening. …

Utilizing Quantum Dots To Enhance Solar Spectrum Conversion Efficiencies For Photovoltaics, Richard N. Savage, Hans Mayer, Matthew Lewis, Dan M. Marrujo

Materials Engineering

Silicon-based photovoltaics typically convert less than 30% of the solar spectrum into usable electric power. This study explores the utilization of CdSe based quantum dots as spectral converters that absorb the under utilized UV portion of the solar spectrum and fluoresce at wavelengths near the band-gap of silicon-based solar cells. A flexible 1 mm thick thin-film structure that contains an array of microfluidic channels is designed and fabricated in polydimethylsiloxane (PDMS) using soft-lithographic techniques. The channels are approximately 85 microns wide by 37 microns tall and are filled with a solution containing the quantum dots. The thin-film structure can easily …

Design, Fabrication, Modeling And Characterization Of Electrostatically-Actuated Silicon Membranes, Brian C. Stahl

Master's Theses

This thesis covers the design, fabrication, modeling and characterization of electrostatically actuated silicon membranes, with applications to microelectromechanical systems (MEMS). A microfabrication process was designed to realize thin membranes etched into a silicon wafer using a wet anisotropic etching process. These flexible membranes were bonded to a rigid counterelectrode using a photo-patterned gap layer. The membranes were actuated electrostatically by applying a voltage bias across the electrode gap formed by the membrane and the counterelectrode, causing the membrane to deflect towards the counterelectrode. This deflection was characterized for a range of actuating voltages and these results were compared to the …

A New Set-Up To Measure The Viscoelastic Properties Of Porous Media Using A Specific Electrodynamic Transducer, Dauchez Nicolas, Olivier Doutres Ph.D., Jean-Michel Génevaux, Guy Lemarquand

Olivier Doutres Ph.D.

A new method for measuring viscoelastic properties of sound absorbing materials is presented. This method is derived from the quasistatic method using a loudspeaker as actuator and sensor. Previous results carried out with a traditional electrodynamic loudspeaker were limited to 100 Hz because of transducer nonlinearities. In this paper, viscoelastic properties are determined up to 500 Hz due to the design of a specific loudspeaker devoid of the main nonlinearities.

Detection Of Voids In Prestressed Concrete Bridges Using Thermal Imaging And Ground-Penetrating Radar, David G. Pollock, Kenneth J. Dupuis, Benjamin Lacour, Karl R. Olsen

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Thermal imaging and ground-penetrating radar was conducted on concrete specimens with simulated air voids. For the thermal imaging inspections, six concrete specimens were constructed during the month of June 2007 to simulate the walls of post-tensioned box girder bridges. The objective was to detect simulated air voids within grouted post-tensioning ducts, thus locating areas where the post-tensioning steel strands are vulnerable to corrosion. The most important deduction taken from these inspections was that PT-ducts and simulated voids were more detectable in the 20 cm (8 in.) thick specimens than in the 30 cm (12 in.) thick specimens. While inspections of …

Improvements In Steel Melting Efficiency -- Industrial Trials, Kent D. Peaslee, Semen Naumovich Lekakh, Edith Martinez

Materials Science and Engineering Faculty Research & Creative Works

Industrial trials were completed to improve energy efficiency in steel melting. First, the benefits of increased chemical energy from an oxyfuel burner and a Co-Jet system in a basic 20 ton electric arc furnace (EAF) were studied. Observations and measurements were made during production before and after the installation of the two systems. The additional chemical energy improved energy efficiency and resulted in increased production. In addition, production using a basic EAF practice was compared to the traditional acid EAF practice. Second, an industrial trial using a 750 lb ladle with a combination of a lightweight alumina castable refractory and …

Energy Efficiency In Steel Casting Production, Raymond Monroe, Kent D. Peaslee, R. Eppich

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

'Fabrication And Characterization Of Polymer Blends And Composites Derived From Biopolymers', Suraj Sharma

All Dissertations

This research focuses on fabricating blends and composites from natural polymers especially from proteins and natural epoxy, and describing the properties of plastics made from them. Specifically, plastic samples from partially denatured feathermeal and bloodmeal proteins, derived from the animal co-products (rendering) industry, were successfully produced through a compression molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. Therefore, this study explored blending methods for …

Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy

All Dissertations

The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility.
Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to …

Using Automated Inclusion Analysis For Casting Process Improvements, Vintee Singh, Semen Naumovich Lekakh, Kent D. Peaslee

Materials Science and Engineering Faculty Research & Creative Works

Different industrial melting and ladle practices (deoxidation, slag, refractory types, etc.) used in steel foundries were analyzed and compared using an ASPEX automated inclusion analyzer for study of inclusions. The effects of deoxidation and pouring practices on the size, type and number of inclusions were evaluated for steel foundries equipped with induction and arc melting furnaces, with capacities ranging from 1 to 20 tons. Samples were collected from the furnace, ladle, and castings. Specific rules were developed for classification of inclusions by composition, size distribution and shape. Inclusion statistics, including composition, quantity, shape, and size during cast steel processing from …

Chitosan/Calcium Phosphate Composites Scaffolds Prepared By Membrane Diffusion Process, P Thanaphat, P Thunyakitpisal, W Techaboonyakiat

Journal of Metals, Materials and Minerals

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) and Dicalcium phosphate dihydrate (CaHPO4.H2O, DCPD) were homogeneously hybridized into chitosan solution by membrane diffusion process. The threedimensional scaffolds were obtained by freeze-drying process. The organic and inorganic contents of scaffold were determined by using thermogravimetry analysis (TGA). The surface morphology of the scaffold and characteristic of calcium phosphate were investigated by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX), and X-ray diffraction (XRD), respectively. Compressive modulus was also determined by dynamic mechanical analysis (DMA). The hybridized inorganic content ranges from 35-45%. Both chitosan/HAp and chitosan/DCPD scaffolds showed interconnected porous structure. The calcium to phosphorus ratios …

Water Soluble Chitosan As An Environment-Friendly Coagulant In Removal Of Rubber Particles From Skim Rubber Latex, R Werathirachot, P Danwanichakul, C Kongkaew, S Loykulnant

Journal of Metals, Materials and Minerals

Water soluble chitosan, dissolved in hot deionized water to obtain 0.8% solution, was used for the coagulation-flocculation of skim natural rubber latex. The efficiency of coagulation-flocculation of skim rubber latex without pH adjustment was much poorer than that of neutral skim rubber latex. When adding chitosan solution to the neutral skim rubber latex with a rubber content of 5.300 %wt/vol until the concentration of chitosan in the dispersion was 0.107%, the phase separation between rubber particles and yellow serum was clearly observed. At this condition, the removal efficiency of skim rubber particles was found to be the best among all …

Electrodeposition Of Nickel Nanowires And Nanotubes Using Various Templates, Asli Ertan, Surendra N. Tewari, Orhan Talu

Chemical & Biomedical Engineering Faculty Publications

Nickel nanotubes and nanowires are grown by galvanostatic electrodeposition in the pores of 1000, 100, and 15 nm polycarbonate as well as in anodised alumina membranes at a current density of 10 mA cm-2. The effects of pore size, porosity, electrodeposition time, effective current density, and pore aspect ratio are investigated. Nickel nanotube structures are obtained with 1000 nm pore size polycarbonate membrane without any prior treatment method. At the early stages of electrodeposition hollow nickel nanotubes are produced and nanotubes turn into nanowires at longer depositon times. As effective current density accounting for the membrane porosity decreases, the axial …

Preparation And Characterization Of Particles From Chitosan With Different Molecular Weights And Their Trimethyl Chitosan Derivatives For Nasal Immunization, W Boonyo, H E. Junginger, N Waranuch, A Polnok, T Pitaksuteepong

Journal of Metals, Materials and Minerals

According to previous studies, molecular weights (MW) of chitosan presented an influence on the level of immune response to model antigen when administering with chitosan through nasal route. Moreover, trimethyl chitosan (TMC) with a degree of quaternization (DQ) of 40%, chitosan derivatives, was also shown to be the most potent nasal OVA delivery platforms compared to TMC with DQ of 20% and 60% in mice model. The aims of this study were to prepare particles from chitosan with difference MW and their TMC derivatives (DQ = 40%) and to characterize size, zeta potential, loading efficiency and release profile in order …

Preparation Of Ultrafine Silver Powder Using Glycerol As Reducing Agent, E Nisaratanaporn, K Wongsuwan

Journal of Metals, Materials and Minerals

The production of silver nanoparticles and sub-micron particles can be achieved by silver alkoxide from silver sulfate and subsequently reducing with glycerol. To reduce the particle size of silver sulfate precursors, ball milling was employed to reduce particle sizes down to 0.81 microns. However, silver sulfate without grinding provided smaller particle sizes of silver particles as opposed to ground specimens. Stirring silver alkoxide simultaneously was efficient to provide for uniform distribution of silver powder. The silver powder thus produced had brain-like shape consisted of very fine aggregate silver particles. The yield of silver powder was in the range of 95-99 …

Influence Of Reinforced Plastomers On Injection Moulds Wear, A Guzanová, J Brezinová

Journal of Metals, Materials and Minerals

The contribution deals with wear of injection moulds based on aluminium alloy Alumec 89 in friction couples with plastomers reinforced with different glass fibres content. Friction relations in injection moulding were simulated by adhesion dry wear test with help of Amsler equipment with area contact of friction couple. Wear intensity was evaluated by friction coefficient and relative wear by weight loss. Simultaneously, changes of aluminium alloy surface morphology after wear in particular friction couples were analysed.

Demonstration Of The Ntc Ceramic Application For Temperature Measurement And Control Using The Labview-Based Measurement System, T Panmatarith, K Poatong

Journal of Metals, Materials and Minerals

In the present paper, ZnO+0.01SnO2 ceramics were prepared using a standard ceramic method. We present the NTC ceramic application for temperature measurement and control using the LabVIEW-based measurement system. The measured resistance of the sample at room temperature was about 6.5 kΩ. The electrical resistance versus temperature of the sample was measured. The negative temperature coefficient of resistance of the sample was -1.018 %/°C. This sample showed NTC effect and exhibited NTC resistor, indicating their potential application as temperature sensor with low cost. It can be used as temperature sensor by using the NTC effect . The measured temperature (T) …

Production Of Sponge Rubber For Monolayer Rubber Stamp Using Salt Leaching Method, W Trakanpruk, Y Rodthong

Journal of Metals, Materials and Minerals

Sponge rubber used for monolayer rubber stamp was produced from nitrile butadiene rubber (NBR). Open cells in sponge rubber were created using salt leaching method. Effect of size and amount of sodium chloride which was used as a water soluble salt on the creation of open cells in the rubber was investigated. Carbon black was used as a filler. A different type of surfactant was added to increase the leaching out of salt from the rubber. Cure characteristics of the compound rubbers: maximum torque, minimum torque, scorch time and cure time as well as hardness of the prepared sponge rubber …

Properties Evaluation Of Sodium Nitrite Treated Chitosan-Cotton Fabric, S Srisuk, K Srikulkit

Journal of Metals, Materials and Minerals

In this study, chitosan coated-cotton fabric was prepared and then treated with sodium nitrite under mild condition, aiming at the partial removal of surface-chitosan in order to solve the problems of surface dyeing and fabric stiffness. The results showed that sodium nitrite treated chitosan-fabric exhibited an improvement of dyeability (higher dye exhaustion and color strength) when compared to untreated fabric. The improvement in dyeability was due to the availability of chitosan amino groups which had an affinity to anionic dyes including reactive dyes. Other fabric properties were evaluated. The results showed that color fastness properties (crocking fastness and light fastness) …

Application Of Chitosan In Rice Production, S Boonlertnirun, C Boonraung, R Suvanasara

Journal of Metals, Materials and Minerals

Chitosan is a natural biopolymer which stimulates growth and increases yield of plants as well as induces the immune system of plants. The objectives of this study were to determine appropriate applications for increasing of the rice yield. The experiment was performed with randomized complete block design ( RCBD) with four replications. Four treatments were done as follows : no chitosan application, seed soaking with chitosan solution, seed soaking and soil application with chitosan solution and seed soaking and foliar spraying with chitosan solution. The results showed that application of chitosan by seed soaking and soil application four times throughout …

Preparation Of N-Acetyl-D-Glucosamine Using Enzyme From Aspergillus Sp., P Setthakaset, R Pichyangkura, A Ajavakom, M Sukwattanasinitt

Journal of Metals, Materials and Minerals

N-acetyl-D-glucosamine (GlcNAc) is one of the basic constituents of mammal cartilage, which is known to help repair deteriorating cartilage and relieve pain and inflammation in osteoarthritis patients. The preparation of GlcNAc from squid pen β-chitin by using Aspergillus sp. chitinase in enzymatic hydrolysis is studied. The cultivation of the fungus in colloidal chitin minimum media at pH 3.5 and 40°C for 5 days gives the highest chitinolytic activity of 3.1 U/mL. The crude enzyme obtained from the the cultivation is used in the hydrolysis of milled squid pen β-chitin (50μm) at pH 4 (acetic acid 2M) and 45°C using 22 …

Chitin Nanowhisker And Chitosan Nanoparticles In Protein Immobilization For Biosensor Applications, P Na Nakorn

Journal of Metals, Materials and Minerals

In this study, bovine serum albumin (BSA) was used as a model protein for the optimization of protein immobilization on chitin nanowhisker and chitosan nanoparticles under different conditions. Chitosan nanoparticles showed better results than chitin in this immobilization purpose. The immobilization at 15 minutes, pH 6 and 20-25°C was the optimal condition. Subsequently, glucose oxidase (GOD), enzyme used for glucose determination, was applied in order to investigate the optimum immobilization condition on chitosan nanoparticles. The optimal condition prove to…at pH 7, 30°C and 0.5 mg/ml of initial GOD concentration via immobilization at 15 minutes. Chitin nanowhisker and chitosan nanoparticles in …