Mechanical Engineering Commons^™

An Experimental Study Of Potential Residential And Commercial Applications Of Small-Scale Hybrid Power Systems, Michael Anthony Acosta

Theses and Dissertations - UTB/UTPA

The research presented in this thesis provides an understanding of small-scale hybrid power systems. Experiments were conducted to identify potential applications of renewable energy in residential and commercial applications in the Rio Grande Valley of Texas. Solar and wind energy converted into electric energy was stored in batteries and inverted to power common household and commercial appliances. Several small to medium size hybrid power systems were setup and utilized to conduct numerous tests to study renewable energy prospects and feasibility for various applications. The experimental results obtained indicate that carefully constructed solar power systems can provide people living in isolated …

A Study On Gas Penetration And Fingering Behavior In Injection Molding Of Polymer And Powder Metal Feedstock, Edna I. Orozco

Theses and Dissertations - UTB/UTPA

The effect of processing variables on the level of gas penetration in parts fabricated by gas-assisted injection molding from two different materials was compared. The materials used were polypropylene and stainless steel powder metal/thermoplastic feedstock. Software simulation and physical experiments were conducted. Taguchi analysis was used to reduce the number of experiment trials and to find the optimum processing conditions. Four different variables were changed using nine different combinations. The processing variables are the pressure, the delay time before gas is injected, the temperature of the material injected, and the amount of the material injected. The results showed that the …

Phase Tunable Holographic Fabrication For Three-Dimensional Photonic Crystal Templates By Using A Single Optical Element, Di Xu, Kevin P. Chen, Ahmad Harb, Daniel Rodriguez, Karen Lozano, Yuankun Lin

Mechanical Engineering Faculty Publications

This paper demonstrates a phase tunable holographic fabrication of three-dimensional photonic lattice structures using a single optical element. A top-cut four-side prism is employed to generate five-beam three-dimensional interference patterns. A silica glass slide is inserted into the optical path to adjust the phase of one interfering beam relative to other four beams. The phase control of the interfering laser beam renders the lattice of the interference pattern from a face-center tetragonal symmetry into a high contrast, interconnecting diamondlike symmetry. This method provides a flexible approach to fabricating three-dimensional photonic lattices with improved photonic band structures.

Thermodynamic, Heat Transfer Analysis And Simulation Of A Domestic Size, Double Stage, Lithium Bromide Absorption System, Carlos R. Lima

Theses and Dissertations - UTB/UTPA

The research presented in this thesis provides an investigation into the thermodynamic and heat transfer requirements for a, 3 ton, Water / Lithium-Bromide absorption system. Thermodynamics results for one stage and two stages absorption system are presented. Heat transfer principles provided a design guideline. Flat-plate, solar, water heaters and auxiliary devices using natural gas were analyzed as the main sources for energy inputs into the generator. Experimental data from the solar collector is provided under several configurations. A TRNSYS simulation of the overall absorption, cooling systems and its alternative energy means provided different scenarios where heating loads into the generator …

Investigation Of The Electromagnetic Interference Shielding Of Titanium Carbide Coated Nanoreinforced Liquid Crystalline Polymer, Karen Lozano, Lesly Espinoza, K. Hernandez, Ananta R. Adhikari, Gangaram Radhakrishnan, P. M. Adams

Mechanical Engineering Faculty Publications

The development and analysis of electrical and electromagnetic interference shielding effectiveness of titanium carbide (TiC)-coated carbon nanofiber (CNF) reinforced liquid crystalline polymer composites are presented. The studied samples consisted of different weight percentages (5, 10, and 15 wt %) of CNFs distributed and dispersed homogeneously within the polymeric matrix. A titanium carbide layer was deposited using pulsed laser deposition, and was conducted at room temperature, which eliminated possible thermal degradation of the polymer matrix. The effect of the thickness of the TiC layer on the electrical properties of the polymeric composites was analyzed. A synergistic behavior between the TiC coating …

Analysis Of Flux-Base Fins For Estimation Of Heat Transfer Coefficient, Kevin D. Cole, Constantine Tarawneh, Brent M. Wilson

Mechanical Engineering Faculty Publications

Exact solutions are given for the transient temperature in flux-base fins with the method of Green’s functions (GF) in the form of infinite series for three different tip conditions. The speed of convergence is improved by replacing the steady part by a closed-form steady solution. For the insulated-tip case, a quasi-steady solution is presented. Numerical values are presented and the conditions under which the quasi-steady solution is accurate are determined. An experimental example is given for estimation of the heat transfer coefficient (HTC) on a non-rotating roller bearing, in which the outer bearing race is treated as a transient fin.

Experiments And Models For The Thermal Response Of Railroad Tapered-Roller Bearings, Constantine Tarawneh, Kevin D. Cole, Brent Wilson, Fadi Alnaimat

Mechanical Engineering Faculty Publications

The need to understand and quantify the heat transfer paths within tapered-roller bearings is of great importance in the railroad industry since bearing cup temperature measurement is the primary tool utilized in the removal of distressed bearings from service. Experiments were performed to acquire temperature histories at several locations on a stationary bearing subjected to heat sources imbedded in two rollers. The experimental results were compared to zero- and first-order thermal models to estimate overall heat transfer coefficients from the bearing. The results presented here can be used to explain some of the mechanisms that lead to overheating of tapered-roller …

Holographic Fabrication Of Photonic Crystals Using Multidimensional Phase Masks, Yuankun Lin, Ahmad Harb, Daniel Rodriguez, Karen Lozano, Di Xu, K. P. Chen

Mechanical Engineering Faculty Publications

This paper reports the experimental approaches to the fabrication of two-layer integrated phase masks and the fabrication of photonic crystal templates using the phase mask based on holographic lithography technique. The photonic crystal template is formed by exposing photoresist mixtures to five-beam interference patterns generated through the phase mask. The fabricated phase mask consists of two layers of orthogonally oriented gratings produced in a liquid crystal and photoresist mixture. A polymerization-induced phase separation preserves the grating structure during the exposure. The vertical spatial separation between two layers of gratings produces a phase difference among diffracted laser beams, which enables the …

Multisensor Processing Algorithms For Underwater Dipole Localization And Tracking Using Mems Artificial Lateral-Line Sensors, Saunvit Pandya, Yingchen Yang, Douglas L. Jones, Jonathan Engel, Chang Liu

Mechanical Engineering Faculty Publications

An engineered artificial lateral-line system has been recently developed, consisting of a 16-element array of finely spaced MEMS hot-wire flow sensors. This represents a new class of underwater flow sensing instruments and necessitates the development of rapid, efficient, and robust signal processing algorithms. In this paper, we report on the development and implementation of a set of algorithms that assist in the localization and tracking of vibrational dipole sources underwater. Using these algorithms, accurate tracking of the trajectory of a moving dipole source has been demonstrated successfully.

Design And Manufacturing Of Functionally Graded Materials With Polymer Chain And Nano-Reinforcement Orientation For Compressive Applications, Sanjay Varma Kalidindi

Theses and Dissertations - UTB/UTPA

Functionally Graded Materials for compressive applications were designed and manufactured by tailoring the properties of Pure Polyethylene (PE) and Vapor Grown Carbon Nanofiber (VGCNF) Reinforced PE Composites. Properties of NRPC have been extensively studied. Properties are dependent on parameters such as the reinforcement/matrix interaction; reinforcement volume fraction, orientation, dispersion, and packing, and the final matrix microstructure. However, there is limited literature on their properties under compression loading. Compression strength studies for high density PE reinforced with VGCNF for different fiber volume fraction (0%, 5%, 10% and 15%) were carried out. The role of interface and alignment was studied. Samples were …

Electrorheology Of Fullerene Suspensions, Maricela Lizcano

Theses and Dissertations - UTB/UTPA

Electrorheological fluids are suspension materials whose rheological behavior changes with an applied voltage. In particular, the material changes from a fluid to a solid behavior with an applied voltage and reverses to its original state when the voltage is removed. This function classifies ER fluids as smart materials. ER fluids may be developed and used as mechanical devices with no mechanical parts such as pumps, actuators, and dampers. Until recently, research was concentrated with micro-particle suspension fluids. This research project investigates the electrorheology of carbon nano-particle suspension.

Comparison Of Sliding Mode And State-Feedback Control Applied To A Partially Treated Actively Constrained Layer Damped (Acld) Beam, Jose J. Rodriguez

Theses and Dissertations - UTB/UTPA

In this research, a sliding mode control (SMC) was utilized in the control of a partially treated, actively constrained layer damped (ACLD), Timoshenko beam model. The resulting vibration control was compared to the vibration control achieved by a state-feedback linear quadratic regulator (LQR) for several loading conditions. An observer was designed and model order reduction (MOR) was performed to achieve a simplified, efficient, and more controllable finite element system model. As a result of model simplification, modeling errors in the form of unstructured uncertainties were introduced into the system. It was determined that the SMC and LQR achieved similar vibration …

A Stochastic Production Cost Model For Remanufacturing Systems, Gaurang S. Patel

Theses and Dissertations - UTB/UTPA

Growing environmental concern throughout this decade coupled with enforced legislation, customer expectations and economic incentives have forced increasing number of manufacturers to take back their products from end user. Managing this reverse flow of products is called reverse logistics. The stochastic nature of returned products complicates the production planning for remanufacturing systems in reverse logistics. In this thesis a stochastic production cost model, considering various costs associated under different situations for remanufacturing systems of returned products is developed. A search algorithm method is recommended to determine optimal production run size, production rate and space for remanufacturing systems in reverse logistics. …

The Effect Of The Shear-Thickening Transition Of Model Colloidal Spheres On The Sign Of N1 And On The Radial Pressure Profile In Torsional Shear Flows, M. Lee, Mataz Alcoutlabi, J. J. Magda, C. Dibble, M. J. Solomon, X. Shi, G. B. Mckenna

Mechanical Engineering Faculty Publications

A novel rheometer plate was used to measure radial pressure profiles during cone-and-plate and parallel-plate shearing flows of a concentrated colloidal dispersion of polymethyl methacryalate spheres suspended in dioctyl phthalate. There is a long history of using suspensions of this type as a model rheological system. The measured pressure profile can be used to calculate N1 and N2, and also provides a check on the flow field in the rheometer. At shear rates just below onset of shear thickening, our measurements show that N1 is positive as predicted by Stokesian dynamics simulations of model Brownian hard spheres, but we are …

Composite Mechanical Property Enhancement Through The Use Of Y-End Shaped Short Fibers, Jin Tan

Theses and Dissertations - UTB/UTPA

This study uses Finite Element Analysis (FEA) to predict the mechanical property enhancement of the composites reinforced by end-shaped short fibers with different aspect ratios and volume fractions at microscale. Fibers used include conventional straight short fibers (CSSF), dumbbell-end shaped short fibers (DSSF), bone-end shaped short fibers (BSSF) and Y-end shaped short fibers (YSSF) with various lengths and angles. The critical distances between neighboring fiber ends for FEA modeling were theoretically deduced and numerically verified. This study has never been done before and the results fill a gap to this field.

In conclusion, planar-end Y-shaped short fiber reinforced composites showed …

Fabrication Of Magnetic Hollow Silica Nanospheres For Bioapplications, L. Shao, Dumitru Caruntu, J. F. Chen, C. J. O'Connor, W. L. Zhou

Mechanical Engineering Faculty Publications

Different kinds of nanospheres are used in magnetic nanosphere fabrication for bioapplications. In this paper, we report a successful synthesis of magnetic hollow silica nanospheres (MHSNS). The MHSNS were fabricated with a one step coating of Fe3O4 magnetic nanoparticles (NPs)(∼10nm) and silica on nanosized (20–100nm) spherical calcium carbonate (CaCO3) surface under alkaline conditions, in which the nanosized CaCO3 were used as nanotemplates and tetraethoxysilane and magnetic NPs were used as precursors. The as-synthesized nanoshperes were immersed in an acidic solution to remove nanosized CaCO3, forming MHSNS. The MHSNS were characterized by SEM, TEM, and SQUID. SEM and TEM results showed …

Extension Of Stereolithography Mold Life Using Gas-Assisted Injection Molding, Dilip Bose Ramalingam Nagarajan

Theses and Dissertations - UTB/UTPA

Stereolithography (SL) molds show great promise for injection molding of limited number of parts, greatly reducing the time to product and production cost. However, they present challenges to designers because of their strength, thermal characteristics and shorter lifetimes compared to metal molds. Gas-assisted injection molding (GAIM) has been used to alleviate the problems of distortion and thermal damage. The use of GAIM makes it possible to produce a large number of parts compared to conventional injection molding in epoxy molds with higher quality. In this research solid models of the mold with different part geometry were created using CAD and …

The Use Of Confidence Intervals For The Control Limits Of X¯ And S Control Charts, Daniel A. Lopez

Theses and Dissertations - UTB/UTPA

This research focuses on the variation observed on the control limits of X¯ and S control charts, due to the sampling schemes. In previous studies it has been shown that the estimated control limits derived by a small number of subgroups does not help in setting up reliable control limits. It has also been shown that estimating control limits from a large number of subgroups is not a feasible option. In this research quantile tables will be derived by sampling from the standard normal distribution and used to explain the effects of sampling on the control limits. The tables will …

The Development Of Web-Based Aerobic And Anaerobic And Muscle Static Work Capacity Modules Using Legacy Cycle Approach, Anant Ravindra Deshpande

Theses and Dissertations - UTB/UTPA

The Legacy cycle is an instructional model that emphasizes inquiry. Learners are faced with progressively complex challenges. For each challenge, learners generate initial thoughts on how they might react to the challenges. In this thesis, a web based instructional method that evaluates interactivity and motivation is presented. The system presented in the thesis helps student to integrate the use of legacy cycle approach in the regular study of aerobic and anaerobic and muscle static work capacity modules. The thesis also focuses on developing modules which contain challenges encompassing various sections, which helps student as an asynchronous learning tool, intended for …

Adaptive Optimal Control Design For Stable Vibration Attenuation Of Active Constrained Layer Damping Beam Structure, Tatyana G. Korotkova-Egan

Theses and Dissertations - UTB/UTPA

Vibration suppression using active constrained layer damping (ACLD) has proven to be an invaluable means for improving the performance of a wide variety of engineering systems. The ACLD creates the hybrid of active and passive damping, attaining favorably high damping characteristics, while at the same time, combines unattractive attributes of both treatments, such as stability sensitivity. Control efforts are needed to achieve an adequate performance of the structures treated with ACLD. The purpose of this research is to investigate theoretically and numerically the adaptive optimal controller of the constrained layer damped beam system, using the classical three-layered distributed-parameter model that …

Dynamic Mechanical And Thermal Analysis Of Aligned Vapor Grown Carbon Nanofibers Reinforced Polyethylene, Jose Jaime Taha-Tijerina

Theses and Dissertations - UTB/UTPA

Dynamic-mechanical and thermal characterization of aligned vapor grown carbon-nanofibers (VGCNFs)-reinforced high-density polyethylene (HDPE) has been performed. VGCNFs with diameters ranging from 50–200nm were used. Nanofibers were purified to remove amorphous carbon and metal catalyst, resulting in deagglomeration, and creating an open network that allowed polymer infiltration during mixing. High-shear mixing was used to disperse and distribute the nanofibers uniformly within the matrix. Extensional flow at different draw ratios (λ) was used to obtain anisotropic nanoreinforced composite (NC) tapes. Dynamic Mechanical Analysis (DMA) showed a dual increase, in storage and loss modulus, with draw ratio. This behavior is attributed to the …

The Effects Of Nationality In The Intercultural Relationship In A Maquila Environment, Cultural Dimensions A Practical Approach, Daniel Martin Reynoso Ortiz

Theses and Dissertations - UTB/UTPA

The Maquiladora Industry has enhanced economic development in the U.S. and Mexico border region. Initially, investors came to set up assembly lines requiring a small amount of technical skill; however, increases in the technological level of products have created the need for companies to require more technical expertise from their staff. Today, the requirement is for the design or redesign of some of their products and the manufacturing processes required to make these products. This brings managerial problems in dealing with technical people in cross cultural environments. These problems deal with staffing issues such as getting the right people and …

Analysis Of Performance Capacity Of Hand Grip Through An Integrated Learning Curve Model, Miguel Torres

Theses and Dissertations - UTB/UTPA

There are few activities or work task in the manufacturing industry that does not involve grip strength. That is why it is in the best interest of the manufacturing industry to have an understanding of the optimum grip strength gain capacity over time that would lead to better performance, accuracy and most of all prevent hand grip related injuries. For that reason, this thesis was concentrated in discovering a possible basic working model for estimating grip strength over time for a specific grip strength activity. The first step was to observe the trend characteristics of the strength gain data over …

Analysis Of Lifting Performance Capacity Through An Integrated Learning Curve Model, Jose Roel Flores

Theses and Dissertations - UTB/UTPA

Physical fitness specific to job demands is necessary for jobs that require moderate or heavy effort. Fitness training is needed not just when a new job is learned but also when an individual has been away from the job for a few weeks and returns to perform the task. The basic problem is to have a good understanding of the dynamics of performance capacities to establish training and retraining regimes to prevent overexertion. To obtain this, a better understanding of the behavior of performance capacity over time is necessary. A performance capacity training regimen was designed for tasks that required …

Human Reliability Analysis In The Performance Of Advanced Cardiac Life Support Tasks, Lucia Veronica Rosas

Theses and Dissertations - UTB/UTPA

Error reduction in the performance of medical emergency situations is an area of great concern in today's society. This is specially the case when the situation involves a cardiac arrhythmia. These situations are generally categorized as Advanced Cardiac Life Support (ACLS) events. The American Heart Association provides the proper procedures that practitioners of ACLS should follow to provide care to patients presenting heart arrhythmia problems. These situations occur inside and outside the hospital, outside the hospital being the most critical ones considering the limitation of equipment and availability of qualified care. Errors made by the practitioners of ACLS in this …

Expert System Development For Hard Disk Drive Failure Analysis, Fernando Rodriguez Rosas

Theses and Dissertations - UTB/UTPA

The Computer's Hard Disk Drive is a complex high technology device, diagnosis of a failure is difficult even using sophisticated test equipments. These Drives are expensive and returning a new one when it fails within the warranty period is not an option. The failed drive must be tested and repaired. In the repair process the analysis and diagnosis of the failures is a key point in the process where decisions regarding the repair process that the failed Drive will follow. Therefore, there is a requirement to perform an effective analysis and provide an accurate diagnosis. The standard system utilized for …

Development Of New Heat Sink Technology For High-Density Microprocessors, Pedro Lopez Jr.

Theses and Dissertations - UTB/UTPA

This study investigates the performance of existing heat sinks and compares it with two heat-exchanger prototypes: aluminum-foam heat sink and PCM (phase-change material)-filled heat sink. Kapton flexible heaters are used to replicate the heat produced by a computer's CPU (central processing unit). A number of thermocouples are connected between the heater and the heat sink being used to measure the component's temperature. The thermocouples are also connected to a data acquisition card to collect the data using a LabVIEW program. The values obtained are compared to data published in literature to validate the experiments and the setup. This setup is …

Near-Field Calculations For A Rigid Spheroid With An Arbitrary Incident Acoustic Field, John P. Barton, Nicholas L. Wolff, Haifeng Zhang, Constantine Tarawneh

Mechanical Engineering Faculty Publications

A general spheroidal coordinate separation-of-variables solution is developed for the determination of the acoustic pressure distribution near the surface of a rigid spheroid for a monofrequency incident acoustic field of arbitrary character. Calculations are presented, for both the prolate and oblate geometries, demonstrating the effects of incident field orientation and character (plane-wave, spherical wave, cylindrical wave, and focused beam) on the resultant acoustic pressure distribution.

Switching Decisions For Diversity Antennas Using Autoregressive Techniques, Sebastian Mani Puthenpurayil

Theses and Dissertations - UTB/UTPA

Decision-making on switching for diversity antennas has been given considerable attention in recent times in mobile radio communications. Due to multipath propagation of radio waves the signals undergo a phenomenon known as fading and there will be considerable reduction in the average signal strength. By having multiple antennas in the receiver or transmitter the signal strength can be improved by switching back and forth to the antenna that has the maximum signal strength. In this thesis we have used linear prediction method for making decisions on which antenna gives the maximum signal strength. Linear prediction is applied on a single …

The Rheological Behavior Of Carbon Nanofiber-Reinforced Thermoplastic Composites, Qiang Zeng

Theses and Dissertations - UTB/UTPA

A rheological study of the thermoplastic HDPE filled with vapor grow carbon nanofiber (VGCNF) has been performed with a RheoStress 150 Tester. VGCNF having average 50 nm diameter were used. These nanofibers were purified to provide for an open network of high purity nanofibers. A rheomixer was used to disperse the nanofibers uniformly in the polyethylene matrix because of shear working conditions. The influence of fiber loading, frequency and temperature on the rheology was investigated. Studies were carried out in the temperature range of 160 to 210°C and frequency range of 0.062 to 628.3 rad/s. The rheological measurements show that …