Mechanical Engineering Commons^™

Neutron-Gamma Discrimination In Elpasolite Scintillator Detector, Brittany Morgan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Existing nuclear stockpiles and weapons-making capabilities imperil the global community. Current nonproliferation efforts involve the research and development of newer, more efficient detection systems that can be deployed for the interdiction and monitoring of special nuclear materials (SNM). Spontaneous and induced fission events in SNM produce neutrons and gamma rays, which can be detected and analyzed, in particular, using scintillator detectors. Various electronic data acquisition systems and data analysis methods have been employed to record and characterize neutron and photon signatures. The goal of this thesis is to develop a new method of discrimination between neutrons and photons in the …

Analyzing Data Of Thin-Film Photovoltaic Cells, Eric Ng, Shubra Bansal

AANAPISI Poster Presentations

The purpose of this study is to determine the basic device characteristics from the Current-Voltage curve of perovskite photovoltaic cells. Martin Green’s “Solar cell efficiency tables (Version 45)” highlighted the accomplishments in photovoltaic cell research for the year 2015. One notable achievement was done by KRICT using perovskites to achieve a 20.1% efficiency. According to Wall Street Journal article “Perovskite Offers Shot at Cheaper Solar Energy”, Ulicia Wang (2014) reports that perovskites have “achieved a jump in efficiency to 20% from around 10% just two years ago.”

Remote Sensing Of Neutron And Gamma Radiation Using Aerial Unmanned Autonomous System, Alex Barzilov, Jessica Hartman, Ivan Novikov

Graduate & Professional Student Association Research Forum

With the continuing advancement of nuclear technologies, the detection and identification of radioactive material is a necessary part of commercial and government applications. There is a wide array of options available for detection and identification of material, but most rely on compact devices which are manually positioned. The deployment of robots equipped with detection equipment is not always feasible, especially in locations where there is considerable debris on the ground, or where there are low clearance areas. To solve this, the goal of this research was to design a remote sensing system for radiation using unmanned aerial vehicles (UAVs). A …

College Of Engineering Senior Design Competition Fall 2015, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

Simulation Of An Air Cooled Single-Effect Solar Absorption Cooling System With Evacuated Tube Collectors, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consistently increasing CO2 emission and ozone depletion from synthetic refrigerants are serious environmental issues challenging the scientific community. Absorption cooling systems give scope of utilizing low grade energy source for generating cooling effect. Solar energy is one of these low grade energy sources and with considering the fact that cooling demand increases with the intensity of solar radiation, solar refrigeration has been considered as a logical solution.

This thesis consists of two different simulation stages, in the first stage, a single effect lithium bromide absorption cooling system with constant cooling capacity is modeled and the effect of ambient and generator …

Sound Attenuation Of Fiberglass Lined Ventilation Ducts, Jacob Albright

UNLV Theses, Dissertations, Professional Papers, and Capstones

Sound attenuation is a crucial part of designing any HVAC system. Most ventilation systems are designed to be in areas occupied by one or more persons. If these systems do not adequately attenuate the sound of the supply fan, compressor, or any other source of sound, the affected area could be subject to an array of problems ranging from an annoying hum to a deafening howl. The goals of this project are to quantify the sound attenuation properties of fiberglass duct liner and to perform a regression analysis to develop equations to predict insertion loss values for both rectangular and …

Designing, Building And Testing A Solar Thermoelectric Generation, Steg, For Energy Delivery To Remote Residential Areas In Developing Regions, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

New alternatives and inventive renewable energy techniques which encompass both generation and power management solutions are fundamental for meeting remote residential energy supply and demand today, especially if the grid is quasi-inexistent. Solar thermoelectric generators can be a cost-effective alternative to photovoltaics for a remote residential household power supply. A complete solar thermoelectric energy harvesting system is presented for energy delivery to remote residential areas in developing regions. To this end, the entire system was built, modeled, and then validated with LTspice simulator software via thermal-to-electrical analogy schemes. Valuable data in conjunction with two novel LTspice circuits were obtained, showing …

An Approach To Model Plastic Deformation Of Metallic Plates In Hypervelocity Impact Experiments, Shawoon Kumar Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Space structures are subjected to micro-meteorite impact at extremely high velocities of several kilometers per second. Similarly, design of military equipment requires understanding of material behavior under extremely high pressure and temperature. Study of material behavior under hypervelocity impact (HVI) poses many challenges since few researchers so far have approached this problem. Material models, equations of the state, and fracture mechanics are not well understood under these conditions.

The objective of this research is to present an approach for studying plastic deformation of metallic plates under HVI conditions. A two-stage light gas gun can be used to simulate these conditions …

The Comparison Of Two Supine Manikins And The Use Of A Shock And Vibration Isolation System For Litter Patients In Air Medical Transport, Karina Karlui Saenz Acosta

UNLV Theses, Dissertations, Professional Papers, and Capstones

Studies show that repeated shock and vibration during aero medical and ground transport are causing patient pain and may be adversely affecting patients’ medical outcome. Patients with spine and head injuries and other severe neurological injuries are the most vulnerable to repeated shock and vibration exposure caused by the vehicle. It is crucial to minimize the effects of these forces on patients during air and ground medical transport. The development of new medical evacuation platforms creates a need to better understand the effects of human exposure to shock and vibration. The use of human subjects to measure whole body vibration …

Cfd Simulation Of Heat Enhancement In Internally Helical Grooved Tubes, Sogol Pirbastami

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heat exchanger devices are widely used in industries, air conditioning systems, refrigeration, etc. These devices have a major role in energy conservation; therefore, increasing the performance of heat exchangers helps save energy, costs and materials. The technique to increase the heat transfer performance is called heat augmentation, which can be applied to pipe surfaces and other surfaces which are used in heat exchangers to improve thermal performance. These techniques are categorized into 3 groups: passive, active and compound technique. In this study a helically machined rectangular groove on the inside of a 2.0 m tube with a diameter of 7.1mm …

Feasibility Study Of Custom Manufacturing Of Ionic Polymer-Metal Composite Sensors, Shelby E. Nelson

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ability to create an ion exchange membrane with any shape or thickness through custom manufacturing techniques is highly desirable in ionic polymer-metal composite (IPMC) research. This is caused by the poor selection and limited availability of certain thicknesses of commercial ion exchange membranes. The objective of this study is to determine the feasibility of manufacturing custom ion exchange membranes for IPMC sensors. The manufacturing methods used in this study are extrusion, injection molding, and hot pressing. A commercial membrane from Golden Energy Fuel Cells (GEFC) is used as a comparison. After the membranes are fabricated, certain properties of the …

College Of Engineering Senior Design Competition Spring 2015, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

The Design, Build, And Validation Of A Hybrid Tower Used To Conduct Helmet Impact Tests, Darren Benn

UNLV Theses, Dissertations, Professional Papers, and Capstones

The National Operating Committee on Standards for Athletic Equipment (NOCSAE) was established to enlist research directed towards the reduction of head injuries in organized sports. The function of the test methods developed by NOCSAE is to provide the blueprint for reliable and repeatable procedures to measure the evaluation of various types of protective sports headgear and projectiles. In addition, the methods also govern hardware such as testing apparatus and data acquisition instrumentation. In helmet testing, the method dictates whether the impact is induced by a projectile system or by a drop tower system with an anvil at the base. Altogether, …

Parameters Identification For A Composite Piezoelectric Actuator Dynamics, Mohammad Saadeh, Mohamed Trabia

Mechanical Engineering Faculty Research

This work presents an approach for identifying the model of a composite piezoelectric (PZT) bimorph actuator dynamics, with the objective of creating a robust model that can be used under various operating conditions. This actuator exhibits nonlinear behavior that can be described using backlash and hysteresis. A linear dynamic model with a damping matrix that incorporates the Bouc–Wen hysteresis model and the backlash operators is developed. This work proposes identifying the actuator’s model parameters using the hybrid master-slave genetic algorithm neural network (HGANN). In this algorithm, the neural network exploits the ability of the genetic algorithm to search globally to …

College Of Engineering Senior Design Competition Fall 2014, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

Designing A Biomimetic Testing Platform For Actuators In A Series-Elastic Co-Contraction System, Ryan Tyler Schroeder

UNLV Theses, Dissertations, Professional Papers, and Capstones

Actuators determine the performance of robotic systems at the most intimate of levels. As a result, much work has been done to assess the performance of different actuator systems. However, biomimetics has not previously been utilized as a pretext for tuning a series elastic actuator system with the purpose of designing an empirical testing platform. Thus, an artificial muscle tendon system has been developed in order to assess the performance of two distinct actuator types: (1) direct current electromagnetic motors and (2) ultrasonic rotary piezoelectric motors. Because the design of the system takes advantage of biomimetic operating principles such as …

Mitigation Of Moving Shocks In An Expanding Duct, Veraun Chipman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inviscid flow theory governs the bulk motion of a gas at some distance away from the walls (i.e. outside the boundary layer). That is to say, there are no viscous forces in the bulk flow, which is modeled using the Euler equations. The Euler equations are simply the Navier-Stokes equations with zero viscosity terms. An ideal inviscid fluid, when brought into contact with a surface or wall, would naturally slip right past it since the fluid has no viscosity. In real life, however, a thin boundary layer forms between the wall or surface and the bulk flow. Shock wave boundary …

Induction Of Differentiation Of Dental Pulp-Derived Mesenchymal Stem Cells (Dpsc), Aubrey Young

UNLV Theses, Dissertations, Professional Papers, and Capstones

Mesenchymal stem cells are derived from a variety of human tissues and are being bioengineered and studied for possible uses in the advancement of medicine. Recent efforts are being focused on Dental Pulp Stem Cells (DPSC's) due to the accessibility of this tissue. Many factors influence DPSC quality and quantity, including the specific methods used to isolate, collect, concentrate, and store these isolates once they are removed. Ancillary factors, such as the choice of media, the selection of early versus late passage cells, and cryopreservation techniques may also influence the differentiation potential and proliferative capacity of DPSC isolates.

The objective …

Neutron Spectroscopy With Scintillation Detectors Using Wavelets, Jessica Hartman

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to study neutron spectroscopy using the EJ-299-33A plastic scintillator. This scintillator material provided a novel means of detection for fast neutrons, without the disadvantages of traditional liquid scintillation materials. EJ-299-33A provided a more durable option to these materials, making it less likely to be damaged during handling. Unlike liquid scintillators, this plastic scintillator was manufactured from a non-toxic material, making it safer to use, as well as easier to design detectors. The material was also manufactured with inherent pulse shape discrimination abilities, making it suitable for use in neutron detection.

The neutron spectral unfolding …

Development Of A Black-Box Transient Thermal Model For Residential Buildings, Andrew Cross

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heavily populated metropolitan areas located in cooling-dominated climates, as are found in the Desert Southwest, pose a challenge to electrical utilities that service these areas. During the late afternoons of the summer months, residents of these metropolitan areas require larger than normal amounts of power to run their homes' air conditioning systems, at significant expense to the utilities. In the study reported here, interior temperature and power consumption data, accumulated over the course of a year and a half from seven houses within a Las Vegas neighborhood, are used to develop a predictive black-box statistical model for residential thermal transience. …

Feedback Speed Control Of A Small Two-Stroke Internal Combustion Engine That Propels An Unmanned Aerial Vehicle, Paul D. Fjare

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unmanned aerial vehicles (UAV) require intelligent control of their power source. Small UAV are typically powered by electric motors or small two-stroke internal combustion (IC) engines. Small IC engines allow for longer flight times but are more difficult to control and cause significant ground noise. A hybrid operation that uses the engine at high altitudes and the electric motors at low altitudes is desired. This would allow for extended flight with acceptable ground noise levels. Since the engine can not be restarted in the air it must be able to remain at idle for an extended time without stalling. A …

Cfd Simulation Of The Thermal Performance Of A Parallel Counter-Parallel Flow Heat Exchanger For The Treatment Of Hypothermia, Alex Heller

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hypothermia is a life-threatening condition. Currently, active warming methods are the most effective treatment for dysthermic patients. The aim of this study is to investigate the use of computational fluid dynamics (CFD) in evaluating the thermal performance of a parallel/counter-parallel flow heat exchanger used as part of a fluid warmer to treat Hypothermia. The 3D model of the heat exchanger is divided into three regions; Infusate (fluid to be heated), Hot Water (heating fluid), and a Solid Region (wall). At the end of the heat exchanger, an elbow section is used to create the counter-parallel flow arrangement specific to this …

Analytical And Experimental Analysis Of Magnetorheological Elastomers, Sarah Trabia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many engineering applications ranging from robotic joints to shock and vibration mitigation can benefit by incorporating components with variable stiffness. In addition, variable stiffness structures can provide haptic feedback (the sense of touch) to the user. In this work, it is proposed to study Magnetorheological Elastomers (MRE), where iron particles within the elastomer compound develop a dipole interaction energy, to be used in a device for haptic feedback. A novel feature of this MRE device is to introduce a field-induced variable shear modulus bias via a permanent magnet and using a current input to the electromagnetic control coil to change …

College Of Engineering Senior Design Competition Spring 2014, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

Bi-Directional Variable Stiffness Magnetorheological Elastomer (Mre) Design, Sarah S. Trabia

College of Engineering: Graduate Celebration Programs

What is MRE?
•MRE is a semi-active silicon with embedded iron particles for variable stiffness changes under external magnetic flux

Research Objective
•Feasibility of using MRE as a haptic feedback device.
•Design a MRE device that can increase or decrease the stiffness.
•Design an effective way of providing a “pre-strain” to the base silicon material.

Computational Simulation
•COMSOL 4.3b Finite Element Analysis
•2D axisymmetric model
•Parametric sweep was run to find the amount of current needed to counteract the permanent magnet.

Investigation Of Phase Change In A36 Steel As A Result Of High Velocity Impact Loading, Mena Slewa

College of Engineering: Graduate Celebration Programs

High velocity projectiles cause severe damage to target materials upon impact. The target material is subject to high pressure and temperature over a very short period of time. This work studies the effects of Lexan projectiles impacting A36 steel at velocities between 3 km/sec and 6 km/sec. The damage zone develops in the target within 5 microseconds. Some steel materials go through a reversible phase change when subject to elevated temperature and high quasi-static pressure. It is unknown whether A36 steel experiences this phase change during high velocity impact. The objective of this work is to investigate if any permanent …

Computational Feasibility Study Of Dual Photon/Neutron Imaging Technique, Jessica Hartman, Alexander Barzilov

College of Engineering: Graduate Celebration Programs

• Non-destructive testing (NDT) is crucial for industrial applications, particularly when imaging of internal components or structures is desired

• Current NDT imaging techniques, such as x-rays, focus primarily on isolating unique shapes. Rarely are these methods capable of distinguishing materials or material composition

• Potential application in the car industry for testing and examining the functional durability of products
  − Vehicle engines are composed of a combination of low-z and high-z materials with significant variation in density
  − Being able to determine the location of material during operation eliminates the need to disassemble an engine during study

Design And Analysis Of Hydrogen Powered Actuator Integrating Metal Hydride Storage System, Md Mainul Hossain Bhuiya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The multi-fold purposes of this dissertation consists of construction, simulation and validation of a model describing hydrogen sorption kinetics in metal hydride. The project involves a comprehensive review of engineering applications involving metal hydrides and furthermore, design and investigation of a thermo-kinetically driven actuation system integrating metal hydrides for compact and soft robotic actuation. This will also shed some light on the feasibility of designing a damping system integrating metal hydride. Firstly, a mathematical model along with comprehensive simulation strategy of hydrogen absorption and desorption processes in porous metal hydride compacts was developed. A two dimensional axisymmetric model was built …

Biomechanical Analysis Of Gait Kinetics Resulting From Use Of A Vacuum Socket On A Transtibial Prosthesis, Maria De Lourdes Ramos Gonzalez

Honors College Theses

The technology and design of lower limb prosthetics have evolved greatly since their introduction. The current study proposed to compare the effects of a conventional pin socket attachment and a vacuum socket attachment for a transtibial amputee. Whereas traditional measurements of gait utilize force plates and camera systems, this study made use of a small tri-axial load cell located at the base of the socket to measure the forces and moments exerted during a regular gait cycle. The hypothesis tested stated that a vacuum pump socket attachment, when compared to a non-vacuum (pin) socket, will have a significant effect on …

Numerical Study Of A Novel Fin Configuration Of A High Temperature Ceramic Plate Fin Heat Exchanger, Vijaisri Nagarajan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Compact heat exchangers are widely used in industries due to their compactness, reduced space, energy requirement and desired thermal performance. The proposed ceramic plate fin heat exchanger (PFHE) based on the offset strip fin design is used in applications which require extreme operating temperatures. It is well known that the compact heat exchanger requires small fins and channels to achieve high heat transfer rate and thermal performances. The fins in the ceramic heat exchanger ensure periodic restart of the boundary layer region which increases the thermal performance or heat transfer enhancement of the heat exchanger.

In this dissertation a novel …