Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Energy Systems (17)
- Physical Sciences and Mathematics (14)
- Applied Mechanics (10)
- Electrical and Computer Engineering (10)
- Biomechanical Engineering (9)
-
- Civil and Environmental Engineering (9)
- Other Mechanical Engineering (9)
- Chemical Engineering (8)
- Environmental Sciences (8)
- Aerodynamics and Fluid Mechanics (7)
- Aerospace Engineering (7)
- Materials Science and Engineering (6)
- Power and Energy (6)
- Biomedical Engineering and Bioengineering (5)
- Computer-Aided Engineering and Design (5)
- Physics (5)
- Transport Phenomena (5)
- Computer Engineering (4)
- Engineering Science and Materials (4)
- Environmental Engineering (4)
- Fluid Dynamics (4)
- Architecture (3)
- Atmospheric Sciences (3)
- Complex Fluids (3)
- Computational Engineering (3)
- Electro-Mechanical Systems (3)
- Environmental Design (3)
- Life Sciences (3)
- Institution
- Keyword
-
- Turbulence (6)
- Turbulence -- Measurement (6)
- Fluid mechanics (5)
- Microfluidics (5)
- Reduced gravity environments (5)
-
- Wakes (Aerodynamics) (5)
- Algorithms (3)
- Biomechanics (3)
- Capillarity (3)
- Mathematical optimization (3)
- Multiphase flow (3)
- Turbulence -- Mathematical models (3)
- Wind turbines (3)
- Anisotropy (2)
- Bubbles -- Effect of reduced gravity on (2)
- Buckling (Mechanics) (2)
- Computer algorithms (2)
- Drops (2)
- Energy harvesting (2)
- Expanded Height (2)
- Fluid mechanics -- Research (2)
- Human locomotion (2)
- Hydrophobic surfaces (2)
- Image processing -- Digital techniques (2)
- Indoor air quality (2)
- Jets -- Fluid dynamics -- Mathematical models (2)
- Microfluidics -- Mathematical models (2)
- Milling-machines (2)
- Neural networks (Computer science) (2)
- Optical pattern recognition (2)
Articles 31 - 60 of 129
Full-Text Articles in Mechanical Engineering
The Optimization Of Machining Parameters For Milling Operations By Using The Nelder Mead Simplex Method, Yubin Lee
Dissertations and Theses
Machining operations need to be optimized to maximize profit for computer numerical control (CNC) machines. Although minimum production time could mean high productivity, it can not guarantee maximum profit rate in CNC milling operations. The possible range of machining parameters is limited by several constraints, such as maximum machine power, surface finish requirements, and maximum cutting force for the stability of milling operations. Among CNC machining parameters, cutting speed and feed have the greatest effect on machining operations. Therefore, cutting speed and feed are considered as main process variables to maximize the profit rate of CNC milling operations.
A variety …
Adapting To Extreme Heat: Social, Atmospheric, And Infrastructure Impacts Of Air Conditioning In Megacities - The Case Of New York City, Harold Gamarro
Adapting To Extreme Heat: Social, Atmospheric, And Infrastructure Impacts Of Air Conditioning In Megacities - The Case Of New York City, Harold Gamarro
Dissertations and Theses
Extreme heat events are becoming more frequent and intense in most large cities. Built-up surfaces also limit cooling mechanisms, leading to warmer conditions in cities, a phenomenon called the Urban Heat Island (UHI). This presents major challenges to reduce adverse health effects of hot weather, particularly in vulnerable populations like the elderly and low-income communities. Here we explore the overall impacts of increasing air conditioning (AC) system adoption in residences as an adaptive measure to reduce human health risks under heat waves, with New York City (NYC) as a case study. This study uses AC adoption data from the 2017 …
A Micromechanics Study On Ferroelectrics And Multiferroic Composites, Zhiming Hu
A Micromechanics Study On Ferroelectrics And Multiferroic Composites, Zhiming Hu
Dissertations and Theses
Two kinds of modern composites are studied in this thesis. One is ferroelectric materials, and the other is the multiferroic composites. Based upon the essential properties of these two types materials, several issues need to be considered in order to study their effective properties. For example, the microstructures of the system including the shape, size and the distribution; the phase connectivity; and the loading conditions will impact the results. First, we focus on the investigation of ferroelectrics and its composites. Based on the experimental observations, the nonlinear electromechanical coupling responses of ferroelectrics are strongly depending on the frequency of the …
Toward Closing The Urban Surface Energy Balance Using Satellite Remote Sensing, Joshua Hrisko
Toward Closing The Urban Surface Energy Balance Using Satellite Remote Sensing, Joshua Hrisko
Dissertations and Theses
The energy exchanges at the Earth’s surface are responsible for many of the processes that govern weather, climate, human health, and energy use. This exchange, commonly known as the surface energy balance (SEB), determines the near-surface thermodynamic state by partitioning the available energy into surface fluxes. The net all-wave radiation is often the primary energy source, while the heat storage and sensible and latent heat fluxes account for the majority of energy distributed elsewhere. While the SEB of various natural environments(trees, crops, soils) has been well-observed and modeled, the urban surface energy balance remains elusive. This is due to the …
On The Energy Sustainability Of Active And Passive Building Integrated Technologies In The Context Of A Changing Climate For Tropical Coastal Cities, Rabindra Pokhrel
On The Energy Sustainability Of Active And Passive Building Integrated Technologies In The Context Of A Changing Climate For Tropical Coastal Cities, Rabindra Pokhrel
Dissertations and Theses
Caribbean Sea surface temperatures have been rising at an alarming rate of 0.020C/year. The effect of rising sea surface temperatures is reflected in increasing in 2m air temperature over the Caribbean. The rise in extreme temperatures increases human discomfort and energy demands for air conditioning (AC) putting both the population and energy infrastructure at higher risk of vulnerability. This vulnerability is amplified in compact cities where anthropogenic heat removal from the built environment further increases the temperature of the urban canyon with feedback on human comfort and energy demands. Although there has been prior work reported on mitigating energy demands …
Capillary Forces And Wetting Dynamics By Diffuse-Interface Modeling, Fanny Thomas
Capillary Forces And Wetting Dynamics By Diffuse-Interface Modeling, Fanny Thomas
Dissertations and Theses
Wetting phenomena underlie many natural and industrial processes, from the proper functioning of the lungs to the thin coating of surfaces. The three-phase interactions involved at microscopic scales play a critical role. Adding solid particles to an emulsion, for example, can drastically change the flow behavior due to capillary bridging between the particles. The study of these three-phase systems is especially relevant to the petroleum industry, where gas hydrates forming large clusters in subsea pipelines during crude oil transportation is a major concern. The dynamics of such systems is also of great interest from a fundamental perspective. Indeed describing non-equilibrium …
Passive Separation Of Binary Fluid Mixtures In Microchannels Using Lattice Boltzmann Method, Mohanad Kamil Radhi
Passive Separation Of Binary Fluid Mixtures In Microchannels Using Lattice Boltzmann Method, Mohanad Kamil Radhi
Dissertations and Theses
Fluid mixtures in real life exist in two forms: miscible and immiscible. Separation of these mixtures using chemical agents or thermal energy has both environmental and economic disadvantages. The high cost and the environmental damage caused by the traditional separation techniques have stimulated both academia and industry to seek alternatives. The emergence of microfluidics offers robust solutions for a broad span of transport problems due to the high surface to volume ratio and reduced length scales. Particularly, the separation efficiency increases significantly due to the aforementioned feature. However, there is still a pressing need of passive separations for the sake …
Tracking Center Of Mass With Limited Inertial Measurement Units, Connor Nathaniel Morrow
Tracking Center Of Mass With Limited Inertial Measurement Units, Connor Nathaniel Morrow
Dissertations and Theses
Wearable motion tracking systems pose an opportunity to study and correct human balance and posture during movement. Currently, these observations are either being conducted in laboratories with the use of camera systems and markers placed on the body, or through the use of suits containing large numbers (15-20) of inertial measurement units. However, to aid with rehabilitation of individuals with impaired balance, there needs to be an option to collect these observations outside of clinics and without incurring much cost from the user. I have focused on three inertial measurement units, one placed on each shank and one placed on …
Non-Contact Distillation, Rawand Muzafar Rasheed
Non-Contact Distillation, Rawand Muzafar Rasheed
Dissertations and Theses
Leidenfrost phenomenon has been studied extensively for its role in applications ranging from nuclear reactor cooling, to metals manufacturing, combustion, and other fields. Herein, Leidenfrost phenomenon is pursued towards non-contact distillation processes with hopes of reducing or even eliminating contaminant fouling. In particular, the microgravity environment of a drop tower is exploited to demonstrate the facility with which droplets achieve and sustain the Leidenfrost state. Dynamic Leidenfrost impacts in microgravity are presented for impacts on hydrophilic and superhydrophobic planar substrates, macro-pillar arrays, confined passageways, and others. Nearly ideal elastic non-contact impacts and droplet oscillation modes are observed. Dynamic Leidenfrost impacts …
Design Of A Canine Inspired Quadruped Robot As A Platform For Synthetic Neural Network Control, Cody Warren Scharzenberger
Design Of A Canine Inspired Quadruped Robot As A Platform For Synthetic Neural Network Control, Cody Warren Scharzenberger
Dissertations and Theses
Legged locomotion is a feat ubiquitous throughout the animal kingdom, but modern robots still fall far short of similar achievements. This paper presents the design of a canine-inspired quadruped robot named DoggyDeux as a platform for synthetic neural network (SNN) research that may be one avenue for robots to attain animal-like agility and adaptability. DoggyDeux features a fully 3D printed frame, 24 braided pneumatic actuators (BPAs) that drive four 3-DOF limbs in antagonistic extensor-flexor pairs, and an electrical system that allows it to respond to commands from a SNN comprised of central pattern generators (CPGs). Compared to the previous version …
Characterizing Tilt Effects On Wind Plants, Ryan Scott
Characterizing Tilt Effects On Wind Plants, Ryan Scott
Dissertations and Theses
Tilting the nacelle of a wind turbine modifies entrainment into the wind plant and impacts total efficiency. Extreme angles can produce flying and crashing wakes where the wake either disrupts entertainment from the undisturbed flow above or is decimated on the ground. The effect of tilt angle on downstream wake behavior was investigated in a series of wind tunnel experiments. Scale model turbines with a hub height and diameter of 12 cm were arranged in a Cartesian array comprised of four rows of three turbines each. Nacelle tilt was varied in the third row from -15° to 15° in chosen …
Infinite Photovoltaic Solar Arrays: Considering Flux Of Momentum And Heat Transfer, Andrew D. S. Glick
Infinite Photovoltaic Solar Arrays: Considering Flux Of Momentum And Heat Transfer, Andrew D. S. Glick
Dissertations and Theses
Large scale solar farms supply an increasing amount of the worlds electricity supply. However, in order to reach cost parity with fossil fuels, further reductions are necessary. Towards this end, photovoltaic (PV) panel cooling becomes increasingly important; high temperatures both decrease efficiency and panel lifetime. To better understand, characterize, and exploit the natural convective cooling of utility scale solar farms, a model solar farm was created. Using both thermal measurements and particle image velocimetry to characterize heat transfer and velocity fields, wind tunnel experiments were conducted using the model solar farm. Three parameters were examined for their effect on heat …
Fatigue Characteristics Of New Eco Series Aluminum 7175 Alloy, Chinh Q.L. Vu
Fatigue Characteristics Of New Eco Series Aluminum 7175 Alloy, Chinh Q.L. Vu
Dissertations and Theses
In this dissertation, the fatigue characteristics of three newly developed experimental compositions for aluminum 7175, with improved mechanical strength, that uses magnesium-calcium alloy instead of pure magnesium are studied.
Specimens of each variant were fabricated and subjected to fatigue life testing, fatigue life data analysis, and observation of their fracture characteristics through optical microscopy and scanning electron microscopy (SEM), and metallography to study their grains and surface characteristics.
Fatigue life testing shows all three variants have a fatigue strength that is approaching approximately 200 MPa. ECO7175v3 is shown to have the highest fatigue strength of approximately 220 MPa at 5x10 …
A Study Of Thermal Energy Storage Of Phase Change Materials: Thermophysical Properties And Numerical Simulations, Kyung-Eun Min
A Study Of Thermal Energy Storage Of Phase Change Materials: Thermophysical Properties And Numerical Simulations, Kyung-Eun Min
Dissertations and Theses
A Thermal Energy Storage (TES) system is meant for holding thermal energy in the form of hot or cold materials for later utilization. A TES system is an important technological system in providing energy savings as well as efficient and optimum energy use. The main types of a TES system are sensible heat and latent heat. A latent heat storage is a very efficient method for storing or releasing thermal energy due to its high energy storage density at constant temperatures, and a latent heat storage material can store 5-14 times more heat per unit volume than a sensible heat …
Wrinkling Of Membrane And Thin Film Under Torsion, Tingting Chen
Wrinkling Of Membrane And Thin Film Under Torsion, Tingting Chen
Dissertations and Theses
Membranes and thin film structures are widely used in modern technologies. Applications include solar sails and sunshields in space missions, biological membranes and flexible circuit boards. Wrinkling of membrane or a stiff film on a soft substrate may occur in either desired or unwanted patterns. This work tries to obtain some understanding on the wrinkling phenomenon and provide guidance in avoiding wrinkling or effectively controlling the wrinkle patterns.
Many works have been published about wrinkling in the thin sheets since the 20th century. However, there is no simple analytical way to systematically characterize the wrinkling in these studies. In …
The Influence Of Size And Progression Of Intra-Cerebral Hematoma On The Lateral Ventricles, Muhammad J. Ashraf
The Influence Of Size And Progression Of Intra-Cerebral Hematoma On The Lateral Ventricles, Muhammad J. Ashraf
Dissertations and Theses
Cerebrovascular diseases like intra cerebral hemorrhage are quite deadly and may disturb functioning of the brain, expanding and resulting in formation of an intra cerebral hematoma(ICH). It is imperative to comprehend how hematoma and its expansion inside the brain endangers human life. One of the influences of an ICH inside brain tissue is on the Lateral Ventricles(LV). When the hemorrhage occurs close enough to the lateral ventricles, filled with cerebrospinal fluid(CSF), it disrupts the balance of fluid in LV. A minor pressure change in LV can negatively influence the production of CSF as well as an increase in intracranial pressure. …
Void Fraction Measurements In Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensor And Pressure Transducers- Effect Of Sparger, Afolabi Gabriel Ojo
Void Fraction Measurements In Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensor And Pressure Transducers- Effect Of Sparger, Afolabi Gabriel Ojo
Dissertations and Theses
The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …
Literature Survey Of Wet-Waste And Hydrothermal Carbonization System: A Comparative Evaluation, Ramat Olaide Yusuf
Literature Survey Of Wet-Waste And Hydrothermal Carbonization System: A Comparative Evaluation, Ramat Olaide Yusuf
Dissertations and Theses
This thesis describes the process of Hydrothermal carbonization and a comparative assessment on recent work done on the process using different feedstocks such as Raw Apple (RA), Apple chip pomace (ACP), apple juice pomace (AJP), grape pomace (GP), macadamia nut-shell (MNS), Sewage Sludge (SS), Poultry Litter (PL) and Grape Marc (GM). The data obtained from the literature survey was compared with the data obtained by the CCL team on the SWPS gasifier (HTC of poultry litter) to obtain how carbon conversion efficiency, syngas composition, thermal efficiency, char production rate, gas production rate and energy utilization vary with carbonization process conditions, …
Void Fraction Measurements In A Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensors And Pressure Transducers: Effect Of Spargers, Afolabi G. Ojo
Void Fraction Measurements In A Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensors And Pressure Transducers: Effect Of Spargers, Afolabi G. Ojo
Dissertations and Theses
The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …
Development Of Electromagnetic Friction Dampers For Improving Seismic Performance Of Civil Structures, Mohsen Amjadian
Development Of Electromagnetic Friction Dampers For Improving Seismic Performance Of Civil Structures, Mohsen Amjadian
Dissertations and Theses
Energy dissipation is critical to limiting damage to civil structures subjected to extreme natural events such as earthquakes. Friction is one of the most reliable mechanisms of energy dissipation that has been utilized extensively in friction dampers to improve seismic performance of civil structures. Friction dampers are well-known for having a highly nonlinear hysteretic behavior caused by stick-slip motion at low velocities, a phenomenon that is inherent in friction and increases the acceleration response of the structure under control unfavorably, in spite of the fact that the displacement is generally reduced because of the energy dissipation. This increase in acceleration …
Thermally (Un-) Stratified Wind Plants: Stochastic And Data-Driven Reduced Order Descriptions/Modeling, Naseem Kamil Ali
Thermally (Un-) Stratified Wind Plants: Stochastic And Data-Driven Reduced Order Descriptions/Modeling, Naseem Kamil Ali
Dissertations and Theses
Wind energy is one of the significant sources of renewable energy, yet a number of challenges preclude optimal operation of wind plants. Research is warranted in order to minimize the power losses and improve the productivity of wind plants. Here, a framework combining turbulence theory and data mining techniques is built to elucidate physics and mechanisms driving the energy extraction of the wind plants under a number of atmospheric/operating conditions. The performance of wind turbines is subjected to adverse effects caused by wake interactions. Therefore, it is crucial to understand wake-to-wake interactions as well as wake-to-atmospheric boundary layer interactions. Experimental …
Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian
Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian
Dissertations and Theses
Ozone in indoor environments can pose a health risk to human occupants; around half of exposure to this pollutant occurs inside buildings. One approach to reducing indoor O3 levels is to mitigate O3 as it enters a building via outdoor air ventilation supply. Often, mechanical systems that introduce outdoor air into buildings are placed on building rooftops. At the urban scale, greenery has been shown to reduce levels of some harmful pollutants, including ozone and cities like Portland, OR, are mandating green roofs be built on large commercial buildings to increase urban green surfaces. We investigate if rooftop …
Chemo-Thermo Cure Of Viscoelastic Materials For Semiconductor Packaging Applications, Anjali Pradeep Kumar
Chemo-Thermo Cure Of Viscoelastic Materials For Semiconductor Packaging Applications, Anjali Pradeep Kumar
Dissertations and Theses
Viscoelastic polymer materials are being actively considered as a novel material for semiconductor packaging applications as a result of their ability to develop strong adhesive bonds at lower temperatures. Viscoelastic thermoset materials are impacted by the stresses generated during the curing process, which is also accompanied by a dissipation of thermal energy. There is a need to develop a generic modeling formulation that is applicable to any material of interest in order to enable the study of different bonding materials and develop optimized curing cycles. This study reports a numerical formulation to evaluate the stress generated and energy dissipated during …
Reliability Of Solder Joints In Embedded Packages Using Finite Element Methods, Valeri Aisha Yunusa
Reliability Of Solder Joints In Embedded Packages Using Finite Element Methods, Valeri Aisha Yunusa
Dissertations and Theses
Solder joints serve as both mechanical and electrical connections between elements in a package. They are subjected to shear strains generated as a result of the different behaviors of the elements in the package (tension and compression) due to the differences in coefficients of thermal expansion during service conditions.
Some of the causes of solder joint failures are due to the following:
Vibration: small rapid displacements of parts of the assembly. This is not necessarily an issue with electronic components but larger parts like automobiles.
Humidity: the package being exposed to water or ionic species can undergo corrosion if an …
Emulating Balance Control Observed In Human Test Subjects With A Neural Network, Wade William Hilts
Emulating Balance Control Observed In Human Test Subjects With A Neural Network, Wade William Hilts
Dissertations and Theses
Human balance control is a complex feedback system that must be adaptable and robust in an infinitely varying external environment. It is probable that there are many concurrent control loops occurring in the central nervous system that achieve stability for a variety of postural perturbations. Though many engineering models of human balance control have been tested, no models of how these controllers might operate within the nervous system have yet been developed. We have focused on building a model of a proprioceptive feedback loop with simulated neurons. The proprioceptive referenced portion of human balance control has been successfully modeled by …
Biomimetic Design And Construction Of A Bipedal Walking Robot, Alexander Gabriel Steele
Biomimetic Design And Construction Of A Bipedal Walking Robot, Alexander Gabriel Steele
Dissertations and Theses
Human balance and locomotion control is highly complex and not well understood. To understand how the nervous system controls balance and locomotion works, we test how the body responds to controlled perturbations, the results are analyzed, and control models are developed. However, to recreate this system of control there is a need for a robot with human-like kinematics. Unfortunately, such a robotic testbed does not exist despite the numerous applications such a design would have in mobile robotics, healthcare, and prosthetics.
This thesis presents a robotic testbed model of human lower legs. By using MRI and CT scans, I designed …
Wind Energy And Wind-Energy-Inspired Turbulent Wakes: Modulation Of Structures, Mechanisms And Flow Regimes, Elizabeth H. Camp
Wind Energy And Wind-Energy-Inspired Turbulent Wakes: Modulation Of Structures, Mechanisms And Flow Regimes, Elizabeth H. Camp
Dissertations and Theses
The interaction of turbulent wakes with one another and with the adjacent fluid directly impacts the generation of electricity in wind turbine arrays. Computational modeling is well suited to the repeated iterations of data generation that may be required to inform understanding of the function of wind farms as well as to develop control schemes for plant function. In order to perform such computational studies, a simplified model of the turbine must be implemented. One of the most computationally efficient parametrizations of the blade utilizes a stationary disk which has a prescribed drag and produces a wake. However, since accurate …
Design Optimization For A Cnc Machine, Alin Resiga
Design Optimization For A Cnc Machine, Alin Resiga
Dissertations and Theses
Minimizing cost and optimization of nonlinear problems are important for industries in order to be competitive. The need of optimization strategies provides significant benefits for companies when providing quotes for products. Accurate and easily attained estimates allow for less waste, tighter tolerances, and better productivity. The Nelder-Mead Simplex method with exterior penalty functions was employed to solve optimum machining parameters. Two case studies were presented for optimizing cost and time for a multiple tools scenario. In this study, the optimum machining parameters for milling operations were investigated. Cutting speed and feed rate are considered as the most impactful design variables …
Relationship Between Anisotropy And Dispersive Stress In Wind Plants With Variable Spacing, Tamara S. Dib
Relationship Between Anisotropy And Dispersive Stress In Wind Plants With Variable Spacing, Tamara S. Dib
Dissertations and Theses
Large eddy simulations are considered for wind plants with varied spanwise and streamwise spacing. Data from five different configurations of staggered and aligned LES wind turbine arrays with a neutrally stratified atmospheric boundary layer are employed for analysis. Fields are analyzed by evaluating the anisotropy stress invariants based on the Reynolds shear stresses and dispersive stress tensor. The relationship between quantities are drawn as a function of the wind plant packing. Reynolds stresses and dispersive stresses are investigated alongside a domain altered version of the second and third scalar invariants, ξ, η, as well as the combination of the …
Stress Analysis Of Embedded Devices Under Thermal Cycling, Sadhana Radhakrishnan
Stress Analysis Of Embedded Devices Under Thermal Cycling, Sadhana Radhakrishnan
Dissertations and Theses
Embedded active and passive devices has been increasingly used by in order to integrate more functions inside the same or smaller size device and to meet the need for better electrical performance of the component assemblies.
Solder joints have been used in the electronic industry as both structural and electrical interconnections between electronic packages and printed circuit boards (PCB). When solder joints are under thermal cyclic loading, mismatch in coefficients of thermal expansion (CTE) between the printed circuit boards and the solder balls creates thermal strains and stresses on the joints, which may finally result in cracking. Consequently, the mechanical …