Studying Effects Of Adhesive Layer On Electrical Signals Of Piezoelectric Transducer Bonded With Structure,
2017
University of Texas at Arlington
Studying Effects Of Adhesive Layer On Electrical Signals Of Piezoelectric Transducer Bonded With Structure, Md Mazharul Islam
Mechanical and Aerospace Engineering Dissertations - Archive
Piezoelectric wafer active sensors (PWAS) are the most attractive transducers for guided-wave or ultrasound based structural health monitoring (SHM) because of their light weight and compact size. In order to excite guided waves in a structure, the PWASs are usually bonded on the surface of the structure by adhesive materials. The electrical signal applied to the surface bonded PWAS is converted to mechanical deformation of the PWAS which in turn is transferred to the structure through the adhesive layer. Thus, understanding the effects of the adhesive layer on the electrical response of the PWAS enables us to optimize the mechanical …
Nonlinear Model Predictive Control For Cooperative Control And Estimation,
2017
University of Texas at Arlington
Nonlinear Model Predictive Control For Cooperative Control And Estimation, Pengkai Ru
Mechanical and Aerospace Engineering Dissertations - Archive
Recent advances in computational power have made it possible to do expensive online computations for control systems. It is becoming more realistic to perform computationally intensive optimization schemes online on systems that are not intrinsically stable and/or have very small time constants. Being one of the most important optimization based control approaches, model predictive control (MPC) has attracted a lot of interest from the research community due to its natural ability to incorporate constraints into its control formulation. Linear MPC has been well researched and its stability can be guaranteed in the majority of its application scenarios. However, one issue …
Characterization Of Vertically Split Distribution-Wet Cooling Media Used In Data Centers,
2017
University of Texas at Arlington
Characterization Of Vertically Split Distribution-Wet Cooling Media Used In Data Centers, Mullaivendhan Varadharasan
Mechanical and Aerospace Engineering Theses - Archive
Data Centers houses substantial number of information technology (IT) equipment like computer servers and storage modules associated with various electronic components which consume high volume of electricity. The IT equipment in data center housing keeps dissipates heat energy as it is constantly running day and night. To keep the data center environment under thermally control and to favor the reliability of electronic components, we need to adopt a cooling technique which aids the module level cooling, with due consideration of the size of the data center and its geographical location. One of the adopted cooling technique in data center thermal …
Composite Plate Optimization With Structural And Manufacturing Constraints,
2017
University of Texas at Arlington
Composite Plate Optimization With Structural And Manufacturing Constraints, Deepak Polaki
Mechanical and Aerospace Engineering Theses - Archive
This is a design optimization study that focuses on the value of free size optimization technology on composite structures which incorporates realistic structural requirements and practical manufacturing limitations to achieve an iterative design with effective structural performance. To detail a study on such practical implementation, a sample structure is required. A rectangular composite laminate with a central hole cutout is considered for this study and is designed using finite elemental tools which includes compression, tension and shear loading conditions with load reactions at bolted joints and buckling stability. Free size optimization and size optimization are used in this study to …
Reliability Assessment Of Solder Joint Using Bga Package – Megtron 6 Versus Fr4 Printed Circuit Boards,
2017
University of Texas at Arlington
Reliability Assessment Of Solder Joint Using Bga Package – Megtron 6 Versus Fr4 Printed Circuit Boards, Mugdha Anish Chaudhari
Mechanical and Aerospace Engineering Theses - Archive
When it comes to the mechanical and electrical seam of the Printed Circuit Board (PCB) and package, reliability of the board plays a major impact on PCB. As the frequency increases, losses in signals increase. This necessitates the use of new materials for such applications. Nelco 4000-13EPSI, Rogers 4350B, Panasonic Megtron 6 are few high-speed materials used. Studies have shown that Megtron 6 has the least dielectric losses so far, low transmission loss, high heat resistance and has low weight loss than the FR-4 boards. With an increasing demand for high performance, reliability and lower costs, the field of electronic …
Solder Joints Design Optimization Of Qfn Packages For Different Boards By Investigating Solder Joint Reliability,
2017
University of Texas at Arlington
Solder Joints Design Optimization Of Qfn Packages For Different Boards By Investigating Solder Joint Reliability, Rishikesh Vilas Tendulkar
Mechanical and Aerospace Engineering Theses - Archive
Quad Flat No-lead package (QFN) is one of the most cutting-edge technologies emerged in the market, exhibiting high performance and efficiency with unparalleled cost effectiveness. QFN, a leadless package, is an ideal choice for applications where size, weight thermal and electrical characteristics are critical, particularly in mobile and handheld devices. Applications like automotive, defense and high current circuits require the package to be mounted on thick printed circuit boards (PCB). The motivation of this work is to understand the effect of design variations of solder joints affecting reliability and optimize the solder package to improve reliability for application on different …
An Improved Method For Measurement Of Radial Thermal Conductivity Of Cylindrical Bodies,
2017
University of Texas at Arlington
An Improved Method For Measurement Of Radial Thermal Conductivity Of Cylindrical Bodies, Salwa Shaik
Mechanical and Aerospace Engineering Theses - Archive
Li-ion cells are ubiquitously found in day to day electronic devices due to their high power density storage capacity. These batteries are known to exhibit sharp reduction in performance at high temperature. Due to this, several attempts have been made in the past to measure thermal properties of the Li-ion cell. This work improves upon past measurements by showing that heat loss during measurements is non-negligible, and by developing an analytical model to account for such heat loss. Experimental measurements carried out on multiple materials demonstrate non-negligible heat loss. When accounted analytically, these data result in thermal conductivity values that …
Electro-Pneumatic Shifting And Servo Control Of A Clutch For A Fsae Racecar,
2017
University of Texas at Arlington
Electro-Pneumatic Shifting And Servo Control Of A Clutch For A Fsae Racecar, Rahul Janardhan Chalmela
Mechanical and Aerospace Engineering Theses - Archive
FSAE is an international student design competition held by SAE International where students design, build and compete in static events like cost, design and dynamic events ranging from acceleration, autocross to endurance. UTA Racing has been a part of FSAE since 1982 and have been using a mechanical design for their shifter and clutch since then. This year for the 2017 design competition an electro-pneumatic system is developed to replace the mechanical system. This system consists of pneumatic cylinders controlling a sequential shifter and a servo clutch. The cylinders are controlled using direction control valves, these receive their signals from …
Rack Level Study Of Hybrid Cooled Servers Using Warm Water Cooling With Variable Pumping For Centralized Coolant System,
2017
University of Texas at Arlington
Rack Level Study Of Hybrid Cooled Servers Using Warm Water Cooling With Variable Pumping For Centralized Coolant System, Chinmay Sanjay Kshirsagar
Mechanical and Aerospace Engineering Theses - Archive
As the worldwide demand for the data centers grows, so does the size and load placed on data centers which leads to the applied constraints on power and space available to the operator. Cooling power consumption is a major contributor of the total energy consumption of the system. In the process of optimization of cooling energy consumption per performance unit, liquid cooling technology has emerged as one of the most viable solutions. In this rack level study, 2OU (Open U) hybrid cooled web servers are tested for an evaluation of warm water cooling in centralized coolant system. Effects of higher …
Load Carrying Capacity Management Of Compound Anisotropic Composite Rings Under External Pressure,
2017
University of Texas at Arlington
Load Carrying Capacity Management Of Compound Anisotropic Composite Rings Under External Pressure, Salman Bakhrayba
Mechanical and Aerospace Engineering Theses - Archive
Composites have much higher strength than conventional materials such as steel. This makes it attractive to replace heavy loaded structural elements, made traditionally from steel, by elements made from composites. However, it is not a trivial task for statically indeterminate structures due to anisotropy of elastic and strength properties of composites. Present investigation is done for a ring subjected to external load. Such rings are used as bulkheads in many applications. Dependence of ultimate external pressure on thickness of the ring is nonlinear one. It is related to non-uniformity of distribution of circumferential stresses, with anisotropy of material, with set …
Comparative Study Of Viscoelastic Modeling And Linear Modeling For Wafer Level Chip Scale Package Under Drop Impact,
2017
University of Texas at Arlington
Comparative Study Of Viscoelastic Modeling And Linear Modeling For Wafer Level Chip Scale Package Under Drop Impact, Navya Sri Reddy Kasi Reddy
Mechanical and Aerospace Engineering Theses - Archive
Wafer level chip scale packages are one the preferred choice in the electronic industry to meet the need of new miniaturization of the recent devices. It has high efficiency in packaging and has low cost. On the other hand, the drop impact failure is one of the growing risk in day to day use of the portable devices. Therefore, to ensure product quality and to integrate more complicated functionality in these devices comprehensive reliability tests need to be performed before delivering the product. Accelerated thermal cycling, drop testing and power cycling are some accepted test methods used to access board …
A Comparative Study Of Wooden And Composite Crossarm Of An Electric Utility Pole,
2017
University of Texas at Arlington
A Comparative Study Of Wooden And Composite Crossarm Of An Electric Utility Pole, Amith Venkatesh
Mechanical and Aerospace Engineering Theses - Archive
Currently, most of the crossarms existing in the nation are made of wood. However, wood has a set of negative features like shorter life span due to environmental cracking, damages by insects and birds. Secondly, an insufficient strength and stiffness which is compensated either by increasing the cross-section or by reducing the span between two poles. Also, it’s reduced insulating property in case of high humidity of air which can be accounted to its hygroscopic behavior. Replacement of wooden crossarms by composite crossarms is a known solution to many problems. However, the existing projects are far from optimal. Present investigation …
Thermal Characterization Of An Isolated Hybrid Cooled Server With Pump And Fan Failure Scenarios,
2017
University of Texas at Arlington
Thermal Characterization Of An Isolated Hybrid Cooled Server With Pump And Fan Failure Scenarios, Uschas Chowdhury
Mechanical and Aerospace Engineering Theses - Archive
Modern day data centers are operated at high power for increased power density, maintenance, and cooling which covers almost 2 percent (70 billion kilowatt-hours) of the total energy consumption in the US. IT components and cooling system occupy the major portion of this energy consumption. Although data centers are designed to perform efficiently, cooling the high-density components is still a challenge. So, alternative methods to improve the cooling efficiency has become the drive to reduce the cooling cost. As liquid cooling is more efficient for high specific heat capacity, density, and thermal conductivity, hybrid cooling can offer the advantage of …
Comparison Of Mechanical Behaviour Of Metallic And Composite Front Door Of A Standard Automobile Car By Fea,
2017
University of Texas at Arlington
Comparison Of Mechanical Behaviour Of Metallic And Composite Front Door Of A Standard Automobile Car By Fea, Aniket Chandu Thosar
Mechanical and Aerospace Engineering Theses - Archive
With the advent of technology, materials have advanced many folds; one such technical revelation has been Fiber-reinforced Composite Materials. Composite materials have two major advantages, among many others: improved strength and stiffness, especially compared to other materials on a unit weight basis and low density with ease of manufacturing. These advantages have led to new aeronautical, automobile and marine designs that are radical departures from past efforts based on conventional materials. This paper focusses on a comparative study between Aluminum Alloys, Manganese alloys, structural steel, Composite materials and investigates the static and dynamic behaviors for a composite front door of …
Experimental And Computational Investigation Of The Need For An Acclimation For Operating It Equipment,
2017
University of Texas at Arlington
Experimental And Computational Investigation Of The Need For An Acclimation For Operating It Equipment, Ramesh Prasanna Manohar
Mechanical and Aerospace Engineering Theses - Archive
Acclimation of IT equipment is not only for newly commissioned equipment but are also for the equipment that is already in use. In conventional Data Center, IT Equipment are cooled by traditional cooling methods, but due to increasing serious energy crisis, Data Centers are Free cooled because of the reduced power consumption. Free Cooling a Data Center is, when the outside air conditions are appropriate, they are drawn into the Data Center to cool the Operating IT Equipment. Data Centers uses dampers to control the type of cooling to be used. Due to a rapid change in the temperature and …
Numerical Study Of Marangoni Convection And Mass Transport In Microdroplets,
2017
University of Texas at Arlington
Numerical Study Of Marangoni Convection And Mass Transport In Microdroplets, Viraj Parag Sabane
Mechanical and Aerospace Engineering Theses - Archive
Marangoni convection is a flow resulting from a surface tension gradient at air/liquid interface caused by temperature gradient, concentration of surfactant or applied electric field. Marangoni convection when caused by temperature gradient is also known as thermo-capillary effect. A microgravity condition presents an ideal case to study this phenomenon, since interfacial forces are dominant over body forces. Hence Marangoni convection inside the micro-droplet was studied both numerically and experimentally. The potential application at micro-scale includes particle separation, chaotic mixing inside the droplet and possible enhancement in liquid liquid extraction. To explore these application, firstly flow field inside a droplet was …
Design And Analysis Of A 10” Carbon Fiber Wheel For A Formula Sae Racecar,
2017
University of Texas at Arlington
Design And Analysis Of A 10” Carbon Fiber Wheel For A Formula Sae Racecar, Pratik Ganesh G Bhagwat
Mechanical and Aerospace Engineering Theses - Archive
Formula SAE is an engineering design competition for students where the goal is to design, build, and compete a Formula-style single seater race vehicle. With a legacy dating back to 1982, UTA Racing has been one of the most competitive teams. In this project, a carbon fiber 10” wheel is designed for the first time, achieving reduced unsprung weight and lower rotational inertia, both of which are key performance characteristics in vehicle dynamics. The design follows Tire and Rim Association guidelines to ensure dimensional compatibility and ease of assembly and is analyzed for 2G cornering with 3G bump. The simulations …
Cfd Optimization Of The Cooling Of Yosemite Open Compute Server,
2017
University of Texas at Arlington
Cfd Optimization Of The Cooling Of Yosemite Open Compute Server, Aditya Gupta
Mechanical and Aerospace Engineering Theses - Archive
Rising energy demands in data centers have constantly made thermal engineers to think and come up with innovative cooling solutions in data centers. It is of utmost importance to have control over the environmental impact of Data Centers. In 2011, the Open Compute Project was started which aimed at sharing energy efficient practices for data centers. The hardware and electrical specifications of the first open compute server – Freedom was shared on open compute project’s website. It was a vanity free design and its components were custom designed. It was deployed in one of the data centers in Prineville, Oregon …
Thermal Optimization And Validation Of Gan High Electron Mobility Transistor,
2017
University of Texas at Arlington
Thermal Optimization And Validation Of Gan High Electron Mobility Transistor, Tanmay Pradip Kavade
Mechanical and Aerospace Engineering Theses - Archive
Gallium Nitride (GaN) is a binary III/V wide band gap semiconductor used in power electronics for operations at high power densities and high speeds. GaN has excellent characteristics like high break-down voltage, high thermal conductivity, and high electron saturation velocity which have led to an intensive study and wide use of GaN in many fields. Some of these fields range from amplifiers, MMIC, laser diodes, pulsed radars and counter-IED jammers to CAT-V modules and fourth generation infrastructure base-stations. Currently GaN devices suffer from high temperature due to self-heating which reduces the mean time to failure. In this study package level …
Conjugate Heat Transfer And Thermo-Structural Analysis Of The Actively Cooled Multi-Stage Conical Nozzle And Hypersonic Low-Reynolds Diffuser Of The New Arc-Heated Wind Tunnel (Awht-Ii) Of The University Of Texas At Arlington,
2017
University of Texas at Arlington
Conjugate Heat Transfer And Thermo-Structural Analysis Of The Actively Cooled Multi-Stage Conical Nozzle And Hypersonic Low-Reynolds Diffuser Of The New Arc-Heated Wind Tunnel (Awht-Ii) Of The University Of Texas At Arlington, David Ray Campbell
Mechanical and Aerospace Engineering Theses - Archive
Arc-heated wind tunnels are the primary test facility for screening and qualification of candidate materials for hypersonic thermal protection systems (TPS). Via an electric arc that largely augments the enthalpy (by tens of MJ/kg) of the working fluid (Air, Nitrogen, CO2 in case of Mars-entry studies) passed through a converging-diverging nozzle at specific stagnation conditions, different regimes encountered in entry and re-entry hypersonic aerothermodynamics can be simulated. Because of the high-enthalpies (and associated temperatures that generally exceed the limits required by the thermo-structural integrity of the facility) the active cooling of the arc-heated wind tunnel’s parts exposed to the working …
