Engineering Commons^™

Synthesis Of Nano/Micro Particles Using Supercritical Method And Particle Characterization, Abhijit Aniruddha Gokhale

Theses

The thesis work consists of the two parts, jet behavior of solvents (ethanol and acetone) and the particle formation using SAS method. In the first part, the study of the effects of process parameters like temperature, pressure, injection velocity and internal diameter of nozzle on liquid jets are studied. The critical pressure for which liquid jet of solvents changes to gas - like jet, is investigated.

In the second part, the experiments are done to study the process of the particle formation using SAS method. Effects of process parameters like pressure, injection velocity of solution, the inner diameter of nozzle …

A Study Of Radiofrequency Cardiac Ablation Using Analytical And Numerical Techniques, Ryan Todd Roper

Theses and Dissertations

Studies on radiofrequency (RF) ablation are often aimed at accurately predicting tissue temperature distributions by numerical solution of the bioheat equation. This thesis describes the development of an analytical solution to serve as a benchmark for subsequent numerical solutions. The solution, which was obtained using integral transforms, has the form of a surface integral nested within another surface integral. An integration routine capable of evaluating such integrals was developed and a C program was written to implement this routine. The surface integration routine was validated using a surface integral with a known analytical solution. The routine was, then, used to …

Incorporating Functionally Graded Materials And Precipitation Hardening Into Microstructure Sensitive Design, Mark Edward Lyon

Theses and Dissertations

The methods of MSD are applied to the design of functionally graded materials. Analysis models are presented to allow the design of compliant derailleur for a case study and constraints are placed on the design. Several methods are presented for relating elements of the microstructure to the properties of the material, including Taylor yield theory, Hill elastic bounds, and precipitation hardening.

Applying n-point statistics to the MSD framework is also discussed. Some results are presented for the information content of the 2-point correlation statistics that follow from the methods used to integrate functionally graded materials into MSD.

For the compliant …

Design And Analysis Of End-Effector Systems For Scribing On Silicon, Bennion Rhead Cannon

Theses and Dissertations

This thesis investigates end-effector systems used in a chemomechanical scribing process. Chemomechanical scribing is a method of patterning silicon to selectively deposit a monolayer of material on the surface of the silicon. This thesis details the development of a unique end-effector for chemomechanical scribing using a compliant mechanism solution. The end-effector is developed to scribe lines that have uniform geometry and produce less chipping on the surface of the silicon. The resulting scribing mechanism is passively controlled, has high lateral stiffness, and low axial stiffness. The mechanism is analyzed using the pseudo-rigid-body model and linear-elastic beam method to determine the …

Modeling For The Control Of The Laser Aided Manufacturing Process (Lamp), Mallikharjuna R. Boddu, Vishnu P. Thayalan, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Many state-of-the-art Rapid Prototyping (RP) technologies adopt lasers to fabricate 3-D solid parts by material deposition in layers. The ability of these RP technologies to control the process requires a thorough understanding of the process mechanics. This paper presents the analysis of an analytical, dynamic model explaining the complex phenomenon of Laser Aided Manufacturing Process (LAMP). The equilibrium of the dynamic model is analyzed and dynamic simulations are performed to determine its stability characteristics. This model forms the basis for the real-time control of the LAMP.

Process Control Of Laser Metal Deposition Manufacturing -- A Simulation Study, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The laser metal deposition process is a rapid manufacturing operation capable of producing functional prototypes with complex geometries and thin sections. This process inherently contains significant uncertainties and, therefore, extensive experimentation must be performed to determine suitable process parameters. An alternative is to directly control the process on-line using feedback control methodologies. In this paper, a nonlinear control strategy based on feedback linearization is created to automatically regulate the bead morphology and melt pool temperature. Extensive simulation studies are conducted to validate the control strategy.

Application Of A Diagnostic Tool In Laser Aided Manufacturing Processes, Sashikanth Prakash, Mallikharjuna Rao Boddu, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lasers play a vital role in producing parts with high dimensional accuracy, strength and quality in today's rapid prototyping industry. In the process of Laser Metal Deposition, many problems are encountered where the part quality does not meet the required standards. This could be due to the nonconformity of control parameters or unnecessary interactions between the control factors. This paper discusses the implementation of Dr. Genichi Taguchiï's optimization techniques using Design of Experiments (DOE) where a series of fractional factorial experiments are performed on the laser deposition process. The results from these experiments are evaluated with respect to the rate …

Mapping Of Ecosystems In Mount Bromo Using Remote Sensing Technology, Bangun Muljo Sukojo

Makara Journal of Technology

Mapping of Ecosystems in Mount Bromo Using Remote Sensing Technology. Covered land analyses of Landsat image have been done to get ecosystem types and map in Mount Bromo region using remote sensing technology. There are nine types of ecosystems in Mount Bromo region, i.e. primary forest, secondary forest, lake, crater, sands, uncovered land, underbrush, dry-field and residence. Distribution of rock analysis has also been done by comparing the manual image interpretation with geological map. The results were coorelated with the digital image interpretation to find rock distribution map which can be useful to get the information about water reservation potencial …

Capacity Of High-Speed Powerline Communication In Vehicles, Deny Hamdani, Ery Safrianti

Makara Journal of Technology

Powerline Communication (PLC) Systems intents to use the mains network in vehicles for high-speed data transmission. Carrier frequencies in the range of MHz are required to establish data rates of some megabits per second. In this paper, typical reference channels extracted from channel measurements are presented and computation results of their capacities according to Shannon’s theorem are presented. Furthermore, the effect of limitations of frequency range and power spectral density of transmitted signal on achievable capacity is investigated. This paper outlines an assessment for theoretical channel capacity and achievable data rates of vehicular PLC transmission schemes. Finally, EMC (Electromagnetics Compatibility) …

Diffuser Optimation At Exhaust System With Catalytic Converter For 110 Cc Mopet With Fluid Flow Cfd Simulation, Tresna P. Soemardi, Ahmad Indra Siswantara, Erwin Erwin

Makara Journal of Technology

Diffuser Optimation at Exhaust System with Catalytic Converter for 110 cc Mopet with Fluid Flow CFD Simulation. CFD simulation used to get behavior of exhaust gas through catalyst, this result will be used to optimize geometry form to perform uniform stream distribution to catalyst, and CFD Simulation will used to analyze backpressure that happened at the model.

The Study On Fluorescence Characteristics Of Chlorella Spp: Ph Influence On Culture, Retno Wigajatri P., Andrianto Handojo, Hendrik Kurniawan, N. B. Prihantini

Makara Journal of Technology

The Study on Fluorescence Characteristics of Chlorella spp: pH Influence on Culture. Experiments for measuring the fluorescence characteristics of Chlorella spp. by using high stability and high repetition rate nitrogen laser of energy 5 mJ with pulse duration of 5 ns have been carried out. The results show that for a cell concentration range from 2,625 cells/ml up to 2,769,000 cells/ml, the fluorescence intensities at pada λ = 687 nm have a linear relationship with the cell concentration. It has been also found that for a 7 days old chlorella culture, the pH variation at the starting culture influenced the …

The Performance Analysis Of A Unicast Network When Two Protocols, Sctp (Stream Control Transmission Protocol) And Tcp (Transmission Control Protocol) Coexist In The Network, Bagio Budiardjo, Michael Thiotrisno

Makara Journal of Technology

This paper elaborates the performance analysis of a unicast network when two protocols, SCTP (Stream Control Transmission Protocol) and TCP (Transmission Control Protocol) coexist in the network. These two protocols are tested using File Transfer Protocol (FTP) and Constant Bit Rate (CBR) based traffic. From the simulations, it could be concluded that SCTP could achieve better throughput compared to TCP in both FTP and CBR based traffic, with sufficiently high fairness index of both intrafairness and interfairness. The increase of simulation time yields to the increase and relatively stable network performance. The increase of the number of sessions of small …

Ultrasound Technique For Prediction Of Statistical Characteristics Of Grid-Generated Turbulence, Tatiana A. Andreeva, William W. Durgin

Office of the Provost Scholarship

Ultrasonic measurement techniques can be used to determine some characteristics of turbulent flows. In this work measurements of the difference in propagation times of ultrasonic waves along two paths are combined with the Kolmogorov (²/₃)-power law to study characteristics of grid-generated turbulence. The paper focuses on ultrasonic measurements of turbulent flow using the travel-time technique. The present research is of interest from two points of view. First, it demonstrates an ultrasonic method of investigation of turbulence, and second, it furthers understanding of the effect of turbulence on sound propagation.

Sufficient Conditions Used In Admittance Selection For Force-Guided Assembly Of Polygonal Parts, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

Admittance control approaches show significant promise in providing reliable force-guided assembly. An important issue in the development of these approaches is the specification of an appropriate admittance control law. This paper identifies procedures for selecting the appropriate admittance to achieve reliable force-guided assembly of planar polyhedral parts for single-point contact cases. A set of conditions that are imposed on the admittance matrix is presented. These conditions ensure that the motion that results from contact reduces part misalignment. We show that, for bounded misalignments, if an admittance satisfies the misalignment-reduction conditions at a finite number of contact configurations, then the admittance …

Volumetric Growth Of Thermoelastic Materials And Mixtures, Stephen M. Klisch, Anne Hoger

Mechanical Engineering

The proteoglycan and collagen constituents of cartilage serve distinct mechanical roles. Changes to the mechanical loading conditions during cartilage growth lead to changes in the concentrations of these molecules and, consequently, the mechanical properties. The main aim of this paper is to present a theory that can describe the mechanical aspects of cartilage growth. The model for cartilage growth is based on a general thermomechanical theory for a mixture of an arbitrary number of growing elastic constituents and an inviscid fluid. Our development of a growth mixture theory is accomplished in two steps. First, the thermodynamics of growing elastic materials …

Learning Real-Time A* Path Planner For Sensing Closely-Spaced Targets From An Aircraft, Jason K. Howlett, Michael A. Goodrich, Timothy W. Mclain

Faculty Publications

This work develops an any-time path planner, based on the learning real-time A* (LRTA*) search, for generating flyable paths that allow an aircraft with a specified sensor footprint to sense a group of closely-spaced targets. The LRTA* algorithm searches a tree of flyable paths for the branch that accomplishes the desired objectives in the shortest distance. The tree of paths is created by assembling primitive turn and straight sections of a specified step size. The operating parameters for the LRTA* search directly influence the running time and path-length performance of the search. A modified LRTA* search is presented that terminates …

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (May. 01 – July 31, 2003), Yingtao Jiang, Bingmei Fu, Woosoon Yim

Transmutation Sciences Materials (TRP)

The report for Y01 has been prepared and submitted. The final part of our apparatus, the N3Si4 stirrer, was received by the end of May. The assembly of the apparatus has almost been completed. The control plan for our apparatus has been revised. To run FLUENT, a high-end Unix-based Sun workstation has been acquired. Plan has been made to ship our apparatus to LANL.

Analysis And Design Of Surface Micromachined Micromanipulators For Out-Of-Plane Micropositioning, Kimberly A. Jensen

Theses and Dissertations

This thesis introduces two ortho-planar MEMS devices that can be used to position microcomponents: the XZ Micropositioning Mechanism and the XYZ Micromanipulator. The displacement and force relationships are presented. The devices were fabricated using surface micromachining processes and the resulting mechanisms were tested. A compliant XYZ Micromanipulator was also designed to reduce backlash and binding. In addition, several other MEMS positioners were fabricated and tested: the Micropositioning Platform Mechanism (MPM), the Ortho-planar Twisting Micromechanism (OTM), and the Ortho-planar Spring Micromechanism (OSM).

Development Of Advanced High Temperature Heat Exchangers: Proposal, University Of Nevada, Las Vegas. Research Foundation

Publications (NSTD)

A research team led by the University of Nevada, Las Vegas (UNLV) Research Foundation proposes a project to develop advanced high temperature heat exchangers (HTHX) for hydrogen production and electrical energy conversion from advanced nuclear reactor concepts. This project will also support the development of Generation IV reactors. The research team includes researchers from UNLV, General Atomics (GA), Sandia National Laboratories (SNL), The University of California, Berkeley UCB) and Oak Ridge National Laboratory (ORNL).

The proposed project will be administered by the University of Nevada Las Vegas Research Foundation (UNLVRF). UNLVRF will provide the overall contract administration and is the …

Development Of An Advanced Stem Heating Model, Joshua L. Jones

Theses and Dissertations

A new one-dimensional heat conduction model for predicting stem heating during fires is presented. The model makes use of moisture and temperature dependent thermal properties for bark and wood. Also, the thermal aspects of the processes of bark swelling, desiccation, and devolatilization are treated in an approximate fashion. Simulation with a surface flux boundary condition requires that these phenomena be accounted for. Previous models have used temperature-time boundary conditions, which prevents them from being directly coupled to fire behavior models. This model uses a flux-time profile for its boundary condition, making it possible to eventually couple it to fire behavior …

Moving Screw Dislocations In Piezoelectric Bimaterials, Xiangfa Wu, Yuris A. Dzenis, Wen-Sheng Zou

Department of Engineering Mechanics: Faculty Publications

An explicit solution for a moving screw dislocation in a piezoelectric bimaterial is given by means of complex variables. The electroelastic fields and forces acting on the moving dislocation are obtained in closed form. As special cases, solutions for a moving screw dislocation in a piezoelectric half-plane with a free or rigid surface are obtained explicitly.

Study Of Geometric Effects On Local Corrosion Rates For Lbe Loop, Chao Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Corrosion is an extremely important issue in nuclear cooling system applications. Many scientific and engineering efforts have been contributed to the research of finding an ideal material, which has resistance to corrosive Lead Bismuth Eutectic (LBE). A Delta Loop was designed and constructed in Los Alamos National Lab (LANL) to obtain the experimental data. This loop is a multi-section closed system that differs in diameter from one part to another. As a result, an intensive study on the geometry effect is hence necessary and valuable. In this thesis, this problem was simulated by commercial software STAR-CD. Results provide a good …

Piezoelectric Sensor In The Application Of Rolling Bearing Health Monitoring, Yinyin Liu

Mechanical & Aerospace Engineering Theses & Dissertations

A condition-based monitoring concept for rolling element bearings in machinery utilizing a piezoelectric load sensor is investigated in this thesis. The radially polarized cylindrical piezoelectric sensor is modeled in its specific coordinates. The sensor registers the stress occurring in all directions around it. The sensor's behavior due to several typical loads is analyzed. Based on the induced stresses in the sensor, the sensor's output as an electric charge can be obtained using the method of integration.

Considering both the normal and tangential loads distributed on the rolling beating's roller-raceway contact surface, the dynamic stress distribution in the outer raceway was …

Optimization-Based Architecture For Managing Complex Integrated Product Development Projects, Hisham Mohamed El-Sayed Abdelsalam

Mechanical & Aerospace Engineering Theses & Dissertations

By the mid-1990's, the importance of early introduction of new products to both market share and profitability became fully understood. Thus, reducing product time-to-market became an essential requirement for continuous competition. Integrated Product Development (IPD) is a holistic approach that helps to overcome problems that arise in a complex product development project. IPD emphasis is to provide a framework for an effective planning and managing of engineering projects. Coupled with the fact that about 70% of the life cycle cost of a product is committed at early design phases, the motivation for developing and implementing more effective methodologies for managing …

Nonlinear Response And Fatigue Estimation Of Aerospace Curved Surface Panels To Acoustic And Thermal Loads, Adam Przekop

Mechanical & Aerospace Engineering Theses & Dissertations

This work presents a finite element modal formulation for large amplitude free vibration of arbitrary laminated composite shallow shells. The system equations of motion are formulated first in the physical structural-node degrees of freedom (DOF). Then, the system is transformed into general Duffing-type modal equations with modal amplitudes of coupled linear bending-inplane modes. The linear bending-inplane coupling is due to the shell curvature as well as unsymmetric lamination stacking. Multiple modes, inplane inertia, and the first-order transverse shear deformation for composites are considered in the formulation. A triangular shallow shell finite element is developed from an extension of the triangular …

Diode Laser Crystallization Of Hydrogenated Amorphous Silicon Thin Films For Solar Cell Applications, Brian A. Eaton

Mechanical & Aerospace Engineering Theses & Dissertations

The research objectives were to prove the crystallization of hydrogenated amorphous silicon (a-Si:H) thin films using a diode laser operating at an 805 nm wavelength and to provide morphology trends in laser crystallized samples. This work was primarily intended for solar cell applications.

One industry goal was to produce a high-efficiency and low-cost solar cell capable of competing economically with other energy sources at large scale in the world market. Excimer laser crystallization was one very promising technique. However, two important problems still hindered economic competition. This research addressed the problems associated with excimer laser crystallization by utilizing a diode …

Analytical Model Of A Thermomechanical Hot Channel Coupled To A Friction Stir Welding Process, Saptarshi Mandal

Mechanical & Aerospace Engineering Theses & Dissertations

Although fusion welding techniques are well established, recent developments in solid state joining techniques have produced high quality welds in materials that are difficult to fusion weld. Friction Stir Welding (FSW) was developed in 1991 as a robust solid-state joining technique that uses a specially shaped rotating tool to generate heat and plasticize material around the tool. The tool then mixes plasticized material along the joint line to produce the weld. Over the last decade, FSW has become increasingly popular for welding aluminum. The combination of attractive properties of the weld and cost-efficiency has led researchers to investigate the feasibility …

A Self-Retracting Fully Compliant Bistable Micromechanism, Nathan D. Masters, Larry L. Howell

Faculty Publications

A new class of fully compliant bistable mechanisms with the added benefit of integrated self-retraction has been developed (hereafter identified as Self-Retracting Fully compliant Bistable Mechanism or SRFBM). A technique using tensural pivots to manage compressive loading in compliant mechanisms is introduced and implemented in the SRFBM. The elimination of traditional kinematic joints and their associated clearance allows a total displacement between stable positions of 8.5 m, and the mechanism size is less than 300 m square when using 2.0 m minimum line widths. Maximum actuation force is approximately 500 N. The SRFBM's small linear displacement and reasonable actuation force …

The Displacement Of The Thermally Grown Oxide In Thermal Barrier Systems Upon Temperature Cycling, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans

Mechanical Engineering Faculty Publications

Models that characterize the displacement instability of the thermally grown oxide (TGO) found in some thermal barrier systems are reviewed, consolidated and extended. It is demonstrated that the simulations are only consistent with the observations whenever the bond coat and TGO both undergo plastic deformation. The TGO yields at the peak temperature, during growth, while the bond coat yields on thermal cycling. The trends oppose. Namely, the TGO displacement is diminished by increasing the high temperature strength of the bond coat, but is increased upon increasing the TGO strength. The model rationalizes certain experimental trends, particularly the decrease in durability …

Identification Of Macro- And Micro-Compliant Mechanism Configurations Resulting In Bistable Behavior, Brian D. Jensen

Theses and Dissertations

The purpose of this research is to identify the configurations of several mechanism classes which result in bistable behavior. Bistable mechanisms have use in many applications, such as switches, clasps, closures, hinges, and so on. A powerful method for the design of such mechanisms would allow the realization of working designs much more easily than has been possible in the past. A method for the design of bistable mechanisms is especially needed for micro-electro-mechanical systems (MEMS) because fabrication and material constraints often prevent the use of simple, well-known bistable mechanism configurations. In addition, this knowledge allows designers to take advantage …