Engineering Commons^™

The Effect Of Material Strain Hardening On The Buckling Strength Of A Perforated Plate Under Uniaxial Loading, Mayuri Suresh Patil

Mechanical and Aerospace Engineering Theses - Archive

Plates or members containing plate elements have been used in the offshore, aerospace and construction industry. Cutouts are often located to lighten the weight of the structure, but these cutouts reduce the ultimate strength of the plate. A number of studies have taken place for determining the buckling strength of a perforated plated but few discuss the effect of material strain hardening on the buckling strength of a perforated plate. Buckling strength is often considered as an important criterial to determine the serviceable limit of the perforated plate in the offshore structure. The aim of the present study is to …

Estimation Of Fracture Mechanics Parameters In 3d Tsv Package During Chip Attachment Process, Mohammed Shahid Ali

Mechanical and Aerospace Engineering Theses - Archive

Nowadays, the packaging of electronic products is becoming revolutionized, since the packages are becoming more and more complex, dense, thinner and lighter for greater portability. Miniaturization of packages is being taken to the next level, and hence, 3D packaging has become a hot topic in the present research area. Three dimensional chips stacking with TSV technology has gained momentum to meet such requirements of significant miniaturization and power reduction which result in increased performance. However, the unique issues related to yield and reliability of critical areas in TSV based 3D ICs need to be evaluated. Therefore, Reliability of such electronic …

Cfd Based Design And Modelling Of Wind Fence To Mitigate High-Speed Wind Loading On A Modular Data Center, Devi Prasad Gorrepati

Mechanical and Aerospace Engineering Theses - Archive

A Modular Data Center (MDC) is a portable method of deploying a data center’s capacity. As an alternative to the traditional data center, an MDC can be placed anywhere data capacity is required. But this comes at the cost of making the MDC operable at any desired location with the environmental factors such as earthquakes and heavy winds. This study focuses on mitigating high-speed wind loading on the MDCs by designing a wind fence to reduce wind speed. Although wind fences are used in many agricultural and farming practices, their usage pertaining to MDCs is very limited. The challenge is …

Enhancement Of Fog-Collection Efficiency Of A Raschel Mesh Using Surface Coatings And Geometric Changes, Mithun Rajaram

Mechanical and Aerospace Engineering Theses - Archive

In a few countries, such as Chile, a Raschel mesh is widely used in the field to collect fog. In this work, we explored the possibility of enhancing fog-collection efficiency of a typical Raschel mesh through surface modification and geometric changes. We demonstrated about 100% enhancement in the fog-collection efficiency.

Tbi Induced Rate Dependent Viscoelastic Response Of Axon: Predictions From A Mathematical Model, Manikanta Jonnalagadda

Mechanical and Aerospace Engineering Theses - Archive

Traumatic brain injury (TBI) accounts to almost one fifth of total fatal injuries. Even though there are various mechanisms hypothesized for the causes leading to TBI, diffuse axonal injury (DAI) is found to be the most observed criterion. The reason for axonal failure in DAI has been studied extensively using experimental and computational models. It was found that axons behave like viscoelastic materials, thus exhibiting rate dependent behavior under loading. This viscoelastic behavior of axons is believed to drive the failure of axons and its substructures. It was observed that axon failure is caused by failures and distortions in axonal …

The Relationship Of Life Prediction For Quad Flat N0-Lead Package (Qfn )Packages Using 4 Point Bend Test And Thermal Cycle Testing, Monisha Mohan

Mechanical and Aerospace Engineering Theses - Archive

In the structural design of the Printed Circuit Boards, the stiffness modulus of the involved Fr4 and Cu layers play an important role. The 4 point bend test is one of the few test methods which is included in the JEDEC standard for the Monotonic Bend characterization for board level interconnects. The study in the past has shown that the damage mechanism of these two testing methods is similar. And also, correlation had been drawn by observation of failure mechanism through Scanning Electron Microscope (SEM). The purpose of this study is to create a methodology for co-relating 4 point bend …

Parametric Study Of An Igbt Cold Plate And Affect Of Device Level Modelling On System Level Thermal Predictions, Abhishek Raj Urs Kadaba Nagaraja Urs

Mechanical and Aerospace Engineering Theses - Archive

In power electronics, as there is continuous increase in performance of the electronic devices, simultaneously the size of the components used in these devices keep on decreasing. This has resulted in increased power densities and the requirements for excellent cooling as well in order to avoid the failure of those devices. Traditionally, while designing a cooling system for a device, uniform heat flux is assumed throughout the components. In many cases this method may not be accurate for a particular model design. There are chances that the heat flux distribution around the components are non-uniform and requires a more accurate …

Additive Manufacturing Methodologies For Multi Process And Multi Material Scenarios, Tushar Saini

Mechanical and Aerospace Engineering Theses - Archive

Additive Manufacturing processes have been developing and continuously improving but are primarily constrained to single materials, albeit some commercial multi extrusion 3D printers do exist where by it is possible to print with multi-colored fluidic polymers or at most two filaments of the same type. 3D printing an object with volumetric varying properties requires manual modification of the G-Code, not a feasible option considering the average size of G-Code generated by the slicing software. This research focuses on developing a post processing methodology that modifies the large G-Code files generated by the slicing software according to user requirements. The proposed …

Board Level Flexural Reliability Testing And Failure Analysis Of Printed Circuit Boards With Wcsp Packages, Guruprasad Shrikant Shinde

Mechanical and Aerospace Engineering Theses - Archive

Printed circuit boards, widely known as PCBs; are the skeleton behind every technology today. Electronics have integrated with every other engineering domain to improve the outcomes. It is very important that they remain intact in slightly extreme physical conditions. They are used in wide range applications which may lead to mechanical stress-strain in some conditions. There are various boards with different kinds of packages on them. A 0.7mm thick board with WCSP; Wafer chip scale package is a prime specimen for my work. The research includes designing exact replica of given PCB into ANSYS and its reliability testing. A 3-point …

Interface Reaction Induced Stress Development In An Aluminum Thin Film Copper Bulk Plate Diffusion Couple, Michael Codie Mishler

Material Science and Engineering Theses - Archive

This thesis investigates the mechanism of the interface reaction induced intermetallic phase formation (IMC) and its impact on the interface reliability in Al-Cu diffusion couple pairing. This study is motivated by the accelerated failure experiments in lead frame to integrated circuit (IC) package wire-bonds using copper (Cu) wire and aluminum (Al) bond-pad that have shown failure most often occurs at the interface of the intermetallic compound (IMC) γ2-phase (Cu9Al4). In order for simulative investigation, we created a diffusion couple consisting of Cu bulk plate coated pure Al thin films with thickness of ~2µm. This configuration is adapted to resemble the …

Influence Of The Volume-Contact Area Ration On The Growth Behavior Of The Cu-Sn Intermetallic Phase, Venkatakamakshi Supraja Giddaluri

Material Science and Engineering Theses - Archive

Solder Joints play a very important role in electronic packaging industry by serving as mechanical support and provides integrity to the device. The increasing demand for high performance, environmental and economic feasibility and miniaturization led to the development of high density interconnects. With the reduction in the size/stand off height of the solder is the reliability issues in the surface mount assemblies and packaging structures under various rigorous environments. One of the most important impact factors that affect the solder joint reliability is the growth rate IMC formed between the solder and substrate. IMC formation is required to ensure good …

Solution Processed Optical Coatings For Solar Cell Applications, Rajesh Tummala

Material Science and Engineering Theses - Archive

In the recent past the demand for higher energy conversion efficiency of solar cells is on the rise. Extensive research is carrying out and many new methods have been proposed by changing either fabrication process or implementation of anti-reflection coatings. In this thesis, the solution processed omni directional anti-reflection coatings have been demonstrated on commercial amorphous silicon solar cells and on fabricated organic solar cells. A simple convective coating technique is utilized to deposit spherical silica micro-particles on the commercial amorphous silicon solar cells and on fabricated organic solar cells. In order to investigate the behavior of solar cells at …

Evaluating And Augmenting Fuel-Saving Benefits Obtained In Aircraft Formation Flight, Wendy Awele Okolo

Mechanical and Aerospace Engineering Dissertations - Archive

When an aircraft flies, it generates wake vortices, which induce a non-uniform wind distribution in its wake. A trail aircraft, placed in the wake of a lead's aircraft vortices experiences this non-uniform wind distribution with varying directions and magnitudes, depending on the location within the wake. It has been demonstrated that there is a "sweet spot" within the wake of a leader in which a trail can experience upwash which leads to reduced drag. Through this mechanism, aircraft can save significant amounts of fuel by flying at the sweet spot of the lead aircraft's wake. This dissertation provides two metrics …

Magnetic Resonance Imaging Of Cerebrovascular Reactivity Using Gas Inhalation Challenges, Harshan Ravi

Bioengineering Dissertations - Archive

Cerebrovascular reactivity (CVR) is a measure of dilation capacity of cerebral vasculature. It is an important biomarker for the vascular functionality and integrity, and may have clinical indications in stroke, atherosclerosis, Moyamoya disease, multiple sclerosis, brain tumor, and other neurological disorders. The most commonly used approach to measure CVR is by applying a physiological maneuver to alter the arterial carbon dioxide (CO2) concentration (e.g. inhaling a small amount of CO2 which is a potent vasodilator), while continuously acquiring BOLD MR images. However, the current method suffers from several limitations related to specificity, sensitivity, and physiological modeling of the measured signal. …

Improving Water Quality Forecasting Using Data Assimilation, Hamideh Riazi

Civil Engineering Dissertations - Archive

Population growth increases agricultural, industrial and human activities which threaten the quality of water resources, especially water supply sources such as lakes and reservoirs. In potentially high-impact situations such as algal blooms, active measures such as controlled release from reservoirs may be necessary. To minimize release while meeting the water quality requirements, accurate short-range water quality forecast is necessary. Because watershed water quality models have a large number of state variables most of which are never observed, their initial conditions (IC) are subject to large uncertainties which may propagate into large forecast errors. In this research, a data assimilation (DA) …

Landfill Volume Gain From The Diversion Of Construction And Demolition Waste, Aayush Raj Tiwary

Civil Engineering Theses - Archive

Construction and Demolition (C&D) waste is one of the major components of the solid waste and is defined as a waste stream resulting from the construction, renovation and demolition of structures such as buildings, roads, and bridges. The amount of C&D waste has been in an upsurge with rapid growth in construction works and is expected to grow even more. As such, the effective waste management for C&D disposal has been a global issue owing to the increasing construction works worldwide. Although landfill disposal of C&D waste is not the preferred method of the C&D waste management, a significant portion …

Estimation Of Rebar Corrosion In Concrete Using Ground Penetrating Radar, Rakesh Krishnarajapete Raju

Civil Engineering Theses - Archive

The purpose of this research was to quantitatively relate the amount of rebar corrosion in concrete with the amplitude of electromagnetic waves generated from Ground penetrating radar (GPR). Many studies have been undertaken on qualitative measurement of corrosion, but there are very few studies regarding estimation of rebar corrosion quantitatively. This experiment involved the use of accelerated corrosion by impressed current technique to corrode the rebar inside the concrete and GPR to determine the extent of corrosion, while making a comparison with a stainless steel bar which was used as a cathode to create a galvanic cell action. Rebars were …

Improving The Rainfall And Flood Frequency Analyses Using Stochastic Storm Transposition Method, Morteza Kiani

Civil Engineering Theses - Archive

Reproduction and realization of historical rainfall events provides foundations for flood and rainfall frequency analyses and the advancement of meteorological studies. Stochastic storm transposition (SST) is a method for such a purpose and enables us to perform frequency analyses by transposing observed historical storm events over any given watershed. The goal of this study is to stochastically examine the impacts of extreme events on all locations in a homogeneity zone. Storms with the same probability of occurrence on a defined homogenous neighborhood will generate various impacts due to spatial and temporal variations of the storms. Transposing storms occurring in the …

Slope Stabilization And Performance Monitoring Of I-35 And Sh-183 Slopes Using Recycled Plastic Pins, Sandip Tamrakar

Civil Engineering Theses - Archive

The United States earth retaining structure market exceeds 170 million square feet annually and there are over 50 different retaining systems to select from which are unique in design and construction. Depending on the type of retaining structure, unit costs vary from less than $20 to in excess of $250 per square foot. Selecting the technically appropriate and cost-effective system is often critical to project cost and schedule. The Recycled Plastic Pin (RPP) has potential to be utilized as a sustainable and cost effective option to stabilize the surficial slope failure. RPP have been successfully used in Missouri, Iowa and …

Experimental Study On Seismic Performance Of Reinforced Concrete Coupling Beams And Rectangular Squat Walls With Innovative Reinforcement Configurations, Poorya Hajyalikhani

Civil Engineering Theses - Archive

Reinforced concrete core walls, coupled by diagonally reinforced coupling beams (DCBs), are a very efficient seismic force resisting system for medium- to high-rise buildings. The diagonal reinforcing bars in DCBs are most effective when the beam has a span-to-depth ratio, ln/h, less than 2. Modern construction, due to architectural requirements, typically requires span-to-depth ratios between 2.4 to 4, which leads to a very shallow angle of inclination of the diagonal reinforcement (generally between 10 to 20 degrees). The lower angles of inclination, combined with the detailing requirements specified in ACI 318, results in reinforcement congestion as well as design and …

Characterization And Comparison Of Fresh And Landfilled Solid Waste, Kavya Koganti

Civil Engineering Theses - Archive

The understanding of the characteristics of Municipal Solid Waste (MSW) is very important in planning, designing and operating and/or upgrading the landfill operation system. It is well anticipated that the fresh MSW will be different from the landfilled MSW due to degradation. However, there is no systematic study on the comparison of physical properties of fresh and landfilled waste from bioreactor and/or enhanced leachate recirculated (ELR) landfills. The most important MSW properties to be considered while planning a landfill system are physical composition, moisture content, unit weight and volatile solids content. These properties are of particular interest especially when an …

Thermo-Hydro-Mechanical Behavior Of Unsaturated Clayey Soils Via Thermo/Suction-Controlled Ring Shear Testing, Jairo Edmundo Yepes Heredia

Civil Engineering Dissertations - Archive

There is a lot of geotechnical infrastructure made of compacted soil, or resting on unsaturated ground, which involves a wide range of deformations. Calculation of foundation settlement, for instance, requires a good estimation of soil stiffness at relatively small strains. Analysis of natural and engineered earth slopes, embankments, and soil bearing capacity, on the other hand, requires good estimations of shear strength, from peak to residual. Besides, despite the critical importance of the thermo-mechanical behavior of unsaturated soils in many geotechnical applications, the effect of relatively high temperature on shear strength and stiffness properties of unsaturated soils is not yet …

A Look At Commercial Building Energy Use And Energy Efficiency Technologies From 1980 To Present, Marvin M. Arroyo

Mechanical Engineering Undergraduate Honors Theses

Energy consumption has increased considerably in the last fifty years as population rises. At the same time, design and efficiency of all equipment used in commercial buildings have changed as well. The purpose of this thesis is to explain how HVAC systems have changed and how they have affected energy consumption. Entities like the US Department of Energy (DOE) and the US Energy Information Administration (EIA) facilitate the data-gathering process by offering databases of energy information from actual monthly energy bills to promote public understanding of energy and its interaction with the economy and the environment. Moreover, in order to …

Industrial Energy Consumption, Benchmarking, And Analysis In The United States, Daniel Maldonado

Mechanical Engineering Undergraduate Honors Theses

The purpose of this paper is to analyze the energy consumption of the industrial sector in the United States, and to identify the tools that can be used to minimize the consumption and improve the energy efficiency of all facilities in the country. The first part of the paper is a historical analysis of the industrial sector energy consumption, where the different energy sources are identified. The second part details different electronic tools that will provide facilities the ability of performing benchmarking, in order to understand their energy performance. Finally, the third part of this paper provides information about the …

Mega Wall Block Welded Wire Mesh Connection, Tyler B. Loertscher

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Mechanically Stabilized Earth (MSE) walls restrain hillslopes to unnatural gradients using reinforced soil. Traditional MSE walls are constructed of large reinforced concrete panels bolted to steel strips for soil reinforcement. Segmented Retaining Walls (SRWs) are a form of MSE walls composed of precast concrete modular blocks that incorporate geosynthetic soil reinforcement. In comparison, traditional MSE walls have faster construction times and are typically stronger, but SRWs have increased in popularity because they are much cheaper to build.

There are many precast companies that produce different SRW block designs, these blocks have facing areas that range from 1 to 13.75 sq. …

Mitigating Pavement Edge Drop Off, Wayne Jensen, Niles Uerling

Nebraska Department of Transportation: Research Reports

The objective of this research was to investigate and document practices currently being used by the Nebraska Department of Roads (NDOR) districts and other State DOTs to mitigate pavement edge drop off. The NDOR has developed (or borrowed) and is currently incorporating into its standard practices several procedures that significantly decrease the incidence and magnitude of pavement edge-drop off. As these practices become more fully integrated into highway reconstruction projects, pavement edge drop off is expected to decrease dramatically. Localized areas of pavement edge drop off along paved lanes with bare or vegetated shoulders were noted as posing particular problems …

Modeling Information Reliability And Maintenance: A Systematic Literature Review, Daysi A. Guerra Garcia

Industrial Engineering Undergraduate Honors Theses

Operating a business efficiently depends on effective everyday decision-making. In turn, those decisions are influenced by the quality of data used in the decision-making process, and maintaining good data quality becomes more challenging as a business expands. Protecting the quality of the data and the information it generates is a challenge faced by many companies across all industrial sectors. As companies begin to use data from these large data bases they will need to begin to develop strategies for maintaining and assessing the reliability of the information they generate using this data. A considerable amount of literature exists on data …

Medium-Range Ensemble Precipitation And Streamflow Forecasting For The Upper Trinity River Basin In Texas Via The Nws Hydrologic Ensemble Forecast Service, Hossein Sadeghi

Civil Engineering Theses - Archive

Compared to forecasts of short-term precipitation accumulations (daily or shorter) at lead times larger than a few days, those of longer-term accumulations (3-daily or longer) are significantly more skillful owing to the larger temporal scale of aggregation. If one can utilize this skill present in medium-range precipitation forecast in hydrologic prediction, it is very likely that the lead time of hydrologic forecasts, in particular, of streamflow and soil moisture may be extended. Though forecasts of longer-term accumulations of precipitation are more skillful than those of shorter-term accumulations, precipitation forecasts in general are too uncertain to be used as deterministic, or …

Feasibility Of Underground Freight Transportation (Uft) In Texas, Seyedeh Hosna Mousavipour

Civil Engineering Theses - Archive

The U.S. economy is expected to double in size over the next 30 years. Truck and rail freight traffic is expected to increase by approximately 45 percent. Air freight is expected to triple in response to demand for the rapid movement of high-value merchandise, while multimodal shipments will likely double. Texas with a gross state product (GSP) of $1.4 trillion dollars is the second largest economy in the U.S. Its size and population, central location, Gulf coastline, and energy resources require a reliable freight transportation system to facilitate further growth. This thesis focuses on the feasibility of Underground Freight Transportation …

Bayesian Statistics And Information Fusion For Gps-Denied Navigation, Brian Lee Copp

Mechanical and Aerospace Engineering Dissertations - Archive

It is well known that satellite navigation systems are vulnerable to disruption due to jamming, spoofing, or obstruction of the signal. The desire for robust navigation of aircraft in GPS-denied environments has motivated the development of feature-aided navigation systems, in which measurements of \textit{environmental features} are used to complement the dead reckoning solution produced by an inertial navigation system. Examples of environmental features which can be exploited for navigation include star positions, terrain elevation, terrestrial wireless signals, and features extracted from photographic data. Feature-aided navigation represents a particularly challenging estimation problem because the measurements are often strongly nonlinear, and the …