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2015

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Articles 5341 - 5370 of 7525

Full-Text Articles in Engineering

Sustainable Methodology For The Use Of Fuel Cells In Data Centers, Vignesh Balasubramanian Jan 2015

Sustainable Methodology For The Use Of Fuel Cells In Data Centers, Vignesh Balasubramanian

Mechanical and Aerospace Engineering Theses - Archive

Data centers have become the lynchpin of the modern economy - from the small to medium-sized organizations, to the enterprise data centers that operates American corporations and the server farms that operate cloud-computing services accommodated by Facebook, Amazon, Google, and others. The booming of cloud storage, extensive data analysis, e-commerce, and internet traffic is also making data centers one of the rapidly growing clients of electricity in developing countries, and one of the key drivers in the construction of new power plants. Key researches are carried out for sustainable development of power usage in data centers. Fuel cells have gone …

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Semi-Active Suspension System Using A Magnetorheological Damper, Abinav Suresh Jan 2015

Semi-Active Suspension System Using A Magnetorheological Damper, Abinav Suresh

Mechanical and Aerospace Engineering Theses - Archive

Magnetorheological (MR) Fluid changes its yield strength when it is subjected to a magnetic field. When this fluid is used inside a damper, it has the ability to change the damping coefficients when it is acted upon by magnetic fields. In this experiment, a MR damper was tested on a shock dyno, where characteristics of the damper was found. Three parameters were changed during the course of the experiment, namely: electric current supplied through the solenoid of the damper, displacement amplitude of the piston and driving frequency of the motor. The results show that there was an increase in damping …

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Development Of Alkali Chlorides As Heat Transfer Fluids With Addition Of Nanoparticles, Sriram Sambasivam Jan 2015

Development Of Alkali Chlorides As Heat Transfer Fluids With Addition Of Nanoparticles, Sriram Sambasivam

Mechanical and Aerospace Engineering Theses - Archive

Recent studies have shown that using a single fluid for Heat Transfer and Thermal Energy Storage, improves the working and efficiency of a CSP. It improves the conversion efficiency (thermal energy to electrical) and also reduce the thermal losses due to heat exchangers by eliminating them. Other methods of storage are thermo chemical TES or phase change TES, but they require heat exchanger between HTF and TES medium, due to which the thermal losses between them are significant. CSP works on a conventional thermodynamic cycle (Rankine Cycle, Brayton Cycle) indicating that higher operating temperature are required to achieve higher efficiency. …

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Dynamics And Control Of The Smart Maintenance And Inspection Robotic Free-Flyer (Smirff), Ameya Rajendra Godbole Jan 2015

Dynamics And Control Of The Smart Maintenance And Inspection Robotic Free-Flyer (Smirff), Ameya Rajendra Godbole

Mechanical and Aerospace Engineering Theses - Archive

The aim of the future space missions would be exploring near earth planets and asteroids. This would mean longer flight durations requiring a space habitat. Longer flight durations would require frequent maintenance and repairs of the space habitat. This would involve the risk of exposing astronauts to the harsh environments while conducting extra-vehicular activities. This risk can be minimised by using a tele-operated free- flying robot. Free- flying robots are a unique class of robots which do not have rigid fixed base and oat in space. A concept of Smart Maintenance Inspection and Robotic Free- flyer (SMIRFF) is presented in …

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Analysis Of A Composite Beam With Unsymmetrical C Crossection, Martin M. Kora Jan 2015

Analysis Of A Composite Beam With Unsymmetrical C Crossection, Martin M. Kora

Mechanical and Aerospace Engineering Theses - Archive

The research work focuses on analysis of composite beam, where a closed form analytical solution was developed to determine the sectional properties of composite beam with unsymmetrical C cross section. The sectional properties such as centroid, equivalent axial stiffness and equivalent bending stiffness are computed. A parametric study of shear center and centroid with different layup sequences was conducted using the developed solution. The ply stresses developed in the C beam is also calculated analytically and is verified by finite element analysis. The result from the proposed theory gives excellent agreement with the ANSYS™

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Test And Evaluation Of An Inlet Barrier Filter To Increase Engine Time-On-Wing For The Bell Boeing V-22 Osprey Tiltrotor, Victor Hwa Jan 2015

Test And Evaluation Of An Inlet Barrier Filter To Increase Engine Time-On-Wing For The Bell Boeing V-22 Osprey Tiltrotor, Victor Hwa

Mechanical and Aerospace Engineering Theses - Archive

The Bell Boeing V-22 Osprey Tiltrotor has seen significant deployment to austere environments where airborne sand and dust is generated due to aircraft operation on, or near, the ground. Current V-22 production aircraft are equipped with an engine air particle separator (EAPS) to remove larger particles of sand and dust, but finer particulates remain an issue for engine combustion air. A prototype engine inlet barrier filter (EIBF) has been developed as a more robust particle filtration solution. Inlet air filtration with the prototype EIBF is expected to quadruple engine time-on-wing by preventing nearly all fine particulates from entering the engine. …

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Manufacturing And Characterization Of Ultra Light Bio-Inspired Nanocomposite Structures, Sushma Pothana Jan 2015

Manufacturing And Characterization Of Ultra Light Bio-Inspired Nanocomposite Structures, Sushma Pothana

Mechanical and Aerospace Engineering Theses - Archive

The inner part of bones is spongy cell-type three dimensional structure called cancellous bone which is the major contributor in keeping the bone weight very low. Yet, bone can sustain body weight and reasonable impact loads implying bone is a naturally optimized light-weight but strong structure. This study demonstrates a novel approach to manufacture bone-like nanocomposite structure for weight saving structural applications. For this, Silicon Carbide (SiC )nano particles are dispersed in SC-15 epoxy resin (a two part liquid resin that solidifies when mixed together at room temperature). Using our novel 3D+ manufacturing technique we developed lighter but stronger nanocomposite …

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Experimental And Simulation Board Level Reliability Assessment Of Wafer Level Chip Scale Packages (Wcsps) Under Thermal Cycling, Hassaan Ahmad Khan Jan 2015

Experimental And Simulation Board Level Reliability Assessment Of Wafer Level Chip Scale Packages (Wcsps) Under Thermal Cycling, Hassaan Ahmad Khan

Mechanical and Aerospace Engineering Theses - Archive

Various studies have been conducted to study the effect of varying board thickness on thermo-mechanical reliability of BGA packages. Wafer level chip scale packages (WLCSP) have also been studied in this regard to determine the effect of PCB build-up thickness on the solder joint reliability. The studies clearly demonstrate that the thinner Printed Circuit Boards (PCBs) result in longer thermo-mechanical fatigue life of solder joints. Due to an extensive research, literature and past trends to support the theory that thinner PCBs perform better than thicker ones, Texas Instruments (TI) opted to move forward by decreasing the thickness of their PCBs …

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Efficient Method To Cool The Data Center Using Solar Energy, Krishna Desai Jan 2015

Efficient Method To Cool The Data Center Using Solar Energy, Krishna Desai

Mechanical and Aerospace Engineering Theses - Archive

Solar energy is the only source which is abundantly available and which can beused to power a cooling system that is based on absorption cycle.Solar cooling system can be used to provide refrigeration for food and medicinesand comfort cooling also. Such systems are specifically applicable to the large applications having large cooling loads for particularly big periods of a year. Peak demandfor the cooling of a building and the highest availability of solar radiation are in similar phase, which makes solar cooling of any building a potential energy source andalso a green solution.In this project, The Lithium bromide-water absorption cycle …

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Analytical Modeling Of Helium Turbomachinery Using Fortran 77, Purushotham Balaji Jan 2015

Analytical Modeling Of Helium Turbomachinery Using Fortran 77, Purushotham Balaji

Mechanical and Aerospace Engineering Theses - Archive

Advanced Generation IV modular reactors, including Very High Temperature Reactors (VHTRs), utilize helium as the working fluid, with a potential for high efficiency power production utilizing helium turbomachinery. Helium is chemically inert and nonradioactive which makes the gas ideal for a nuclear power-plant environment where radioactive leaks are a high concern. These properties of helium gas helps to increase the safety features as well as to decrease the aging process of plant components.The lack of sufficient helium turbomachinery data has made it difficult to study the vital role played by the gas turbine components of these VHTR powered cycles. Therefore, …

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Design And Cfd Analysis Of The Intake Manifold For The Honda Cbr250rr Engine, Subhash Seshadri Jan 2015

Design And Cfd Analysis Of The Intake Manifold For The Honda Cbr250rr Engine, Subhash Seshadri

Mechanical and Aerospace Engineering Theses - Archive

The scope of this project is to improve reliability issues on a turbocharged Honda CBR250RR engine and boost the performance by redesigning the intake manifold - one of the key components of this engine package. The engine has been used in the past by the UTA Formula SAE team in several open-wheeled race cars providing a light weight platform with a high power to weight ratio. Previous intake manifolds did not provide balanced distribution of air flow among all cylinders. This lead to incorrect air/fuel ratios were some cylinders ran too lean at times, while others were running too rich. …

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Numerical Investigation Of Steady State And Transient Thermal Performance Of A Multi-Chip Vapor Chamber, Mohammad Parhizi Jan 2015

Numerical Investigation Of Steady State And Transient Thermal Performance Of A Multi-Chip Vapor Chamber, Mohammad Parhizi

Mechanical and Aerospace Engineering Theses - Archive

Effective dissipation of heat generated in microelectronic devices during operation is critical for reliability and performance, particularly for advanced architectures such as microserver chips. Vapor chambers are a class of heat spreaders that have received much recent attention due to their passive nature and superior heat spreading capability. Several studies have investigated thermal performance of vapor chambers as heat spreading devices. However, developing a simple and accurate model which could be easily used in industry is still a big challenge. Moreover, more work needs to be done to optimize the performance of vapor chambers. For instance, developing a vapor chamber …

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Developing A 7mmx7mm Qfn Package Using Liquid Crystal Polymer, Mitul H. Naik Jan 2015

Developing A 7mmx7mm Qfn Package Using Liquid Crystal Polymer, Mitul H. Naik

Mechanical and Aerospace Engineering Theses - Archive

Quad Flat No-Lead (QFN) packages are one of the most widely used and popular packages in the industry. The QFN packages gained popularity in the last decade because of its excellent electrical/thermal characteristics and lower costs. QFN packages are widely used in automotive, defense, handheld devices where space is a constraint and high current circuits require the package is mounted on thick printed circuit boards. This work makes an attempt to develop an economical 7mm*7mm QFN package using Liquid Crystal Polymer (LCP).The first challenge in this work investigate the different grades of LCP to match the electrical as well as …

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Fluid-Crack Interaction In Hydraulic Fracturing, Harshil Vora Jan 2015

Fluid-Crack Interaction In Hydraulic Fracturing, Harshil Vora

Mechanical and Aerospace Engineering Theses - Archive

Hydraulic fracturing has been one of the major improvements in petroleum engineering in the past few decades. Since then this process has been used progressively and over million wells have been fracked using hydraulic fracturing technology. A thorough understanding of the formation of fracture network and its propagation is essential to keep evolving the technology. In the present study, the Linear Elastic Fracture Mechanics (LEFM) approach is applied to the crack propagation to understand the fluid crack interaction in brittle rocks under hydraulic loading. The boundary element method (BEM) is used to carry out the numerical analysis. Additionally, an explicit …

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Design And Optimization Of Under Tray For Formula Sae Race Car Using Cfd Analysis, Girish Bangalore Jalappa Jan 2015

Design And Optimization Of Under Tray For Formula Sae Race Car Using Cfd Analysis, Girish Bangalore Jalappa

Mechanical and Aerospace Engineering Theses - Archive

With the advent of inverted wings to produce down-force in Formula-1 during the 1960's, aerodynamics has played a big role in increasing the vehicle performance. An aerodynamics system consists of front, rear wings and an under-tray. This thesis focuses on design of a new under-tray using CFD analysis for a Formula-SAE car.

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Simulation Of Indeterminate Multiple, Simultaneous Impact And Contact For A Flexible Multibody System, Rohit Vijay Katti Jan 2015

Simulation Of Indeterminate Multiple, Simultaneous Impact And Contact For A Flexible Multibody System, Rohit Vijay Katti

Mechanical and Aerospace Engineering Theses - Archive

This work presents a method for understanding the impact behaviour of a flexible body undergoing multiple, simultaneous contacts. A continuous model is used with an event-driven function in MATLAB, which detects the collisions. The flexible body is defined as a system of particles, having inter-particle forces in terms of spring, damper coefficients. Equations of motion for such a Flexible MultiBody system are determined and then solved for different phases.In the method presented, the indeterminate nature of equations of motion encountered, during impact, and contact for flexible body are examined. Constraint forces are determined during the different phases of an impact …

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Thermo-Mechanical Design Considerations At The Server And Rack Levels To Achieve Maximum Data Center Energy Efficiency, Richard Mark Eiland Jan 2015

Thermo-Mechanical Design Considerations At The Server And Rack Levels To Achieve Maximum Data Center Energy Efficiency, Richard Mark Eiland

Mechanical and Aerospace Engineering Dissertations - Archive

Continually increasing demand for information technology (IT) applications and services has provided sustained growth and interest in data centers. The large amounts of energy consumed by data center facilities have placed a significant emphasis on the energy efficiency of their overall operation. One area of particular importance is the cooling energy required. Heat generation within a data center starts at the server level, specifically within the microelectronic devices that process digital information. Convective heat transfer is the primary driver for the removal of heat from an individual server. As such, cooling efficiency at the server level will be dictated by …

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Nanoscale Toughening Mechanisms Of Ultra High Temperature Novel Hfb2 Based Multiphase Ceramics, Zoher Shabbir Lavangia Jan 2015

Nanoscale Toughening Mechanisms Of Ultra High Temperature Novel Hfb2 Based Multiphase Ceramics, Zoher Shabbir Lavangia

Mechanical and Aerospace Engineering Theses - Archive

During return of spacecraft they endure very high temperatures (3000°F), few materials can withstand temperatures this high along with additional loads of the spacecraft. Reinforced carbon-carbon (RCC) material system is used as Thermal Protection System (TPS) which is made of laminated graphite rayon-phenolic epoxy, which need to sustain extreme heat. However, these materials are very prone to premature degradation due to oxidation. Silicon Carbide (SiC) and Hafnium Diboride (HfB2) are candidate materials for TPS but, they inherently lack the required toughness for such applications. This research is carried out in two stages, first is to study the individual properties of …

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Minimizing Power Consumption At Module, Server And Rack-Levels Within A Data Center Through Design And Energy-Efficient Operation Of Dynamic Cooling Solutions, John Edwards Fernandes Jan 2015

Minimizing Power Consumption At Module, Server And Rack-Levels Within A Data Center Through Design And Energy-Efficient Operation Of Dynamic Cooling Solutions, John Edwards Fernandes

Mechanical and Aerospace Engineering Dissertations - Archive

Data center energy consumption continues to increase with the proliferation in online services such as social networking, banking, entertainment, cloud computing, etc. Recent estimates show that associated power consumption accounts for around 2% and 1.8% of electricity production in the United States and worldwide respectively. In addition to growth in the industry, power densities continue to rise in IT equipment increasing the criticality of thermal management in data center operation. Cooling systems account for around a third of overall power consumption requiring more energy-efficient solutions across all levels within the facility.Liquid cooling of high power modules using cold plates has …

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Formalization Of The Engineering Science Discipline - Knowledge Engineering, Xiao Peng Jan 2015

Formalization Of The Engineering Science Discipline - Knowledge Engineering, Xiao Peng

Mechanical and Aerospace Engineering Dissertations - Archive

Knowledge is the most precious ingredient facilitating aerospace engineering research and product development activities. Currently, the most common knowledge retention methods are paper-based documents, such as reports, books and journals. However, those media have innate weaknesses. For example, four generations of flying wing aircraft (Horten, Northrop XB-35/YB-49, Boeing BWB and many others) were mostly developed in isolation. The subsequent engineers were not aware of the previous developments, because these projects were documented such which prevented the next generation of engineers to benefit from the previous lessons learned. In this manner, inefficient knowledge retention methods have become a primary obstacle for …

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The Effects Of Deposition Conditions On The Mechanical Properties Of Titanium Silicon Nitride Nanocomposite Coatings, Suo Liu Jan 2015

The Effects Of Deposition Conditions On The Mechanical Properties Of Titanium Silicon Nitride Nanocomposite Coatings, Suo Liu

Material Science and Engineering Theses - Archive

Titanium Silicon Nitride has received much attention in recent years for its theoretical super hardness and oxidation resistance at high temperature. In this work, the mechanical properties of TiSiN thin films including hardness, coefficient of friction, wear rate, wear mechanism were studied in detail using nanoindentation, pin-on-disk tribometer, optical profilometer, SEM and XPS. Four deposition conditions were varied to find the optimal conditions that produce the TiSiN film with the highest hardness and the best wear resistance. First, four substrate biases (100V, 200V, 300V, and 500V) were used, respectively. Then, different power (50W, 55W, 60W) and different N2 ratio (20%, …

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Aspects Of Intuitive Control Framework: Stabilize, Optimize, And Identify, Pavan Kumar Nuthi Jan 2015

Aspects Of Intuitive Control Framework: Stabilize, Optimize, And Identify, Pavan Kumar Nuthi

Mechanical and Aerospace Engineering Dissertations - Archive

The duality of estimation and control problems is a well known fact in control theory literature. Parameter convergence and closed loop stability are usually competing interests for a given control scheme. This motivates identification routines to be performed only in offline experiments. On the other hand stable controllers do not guarantee parameter convergence to true parameters. Thus there is a need for a higher level abstraction for a control scheme which acts in stages and prioritizes various aspects at different stages. The stage abstraction for controller is inspired by human intuition towards dealing with control and identification simultaneously and hence …

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A Numerical Study Of Microfluidic Droplet Motions In Parallel-Plate Electrowetting-On-Dielectric (Ewod) Devices, Yin Guan Jan 2015

A Numerical Study Of Microfluidic Droplet Motions In Parallel-Plate Electrowetting-On-Dielectric (Ewod) Devices, Yin Guan

Mechanical and Aerospace Engineering Dissertations - Archive

Microscale water droplet motions in parallel-plate electrowetting-on-dielectric (EWOD) devices including transport, splitting, merging and dispensing have been numerically studied. The transient governing equations for the microfluidic flow are solved by a finite volume scheme with a two-step projection method on a fixed computational domain. The interface between liquid and gas is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. A continuum surface force (CSF) model is employed to model the surface tension at the interface. Contact angle hysteresis which is an essential component in EWOD modeling is implemented together with a simplified model for the viscous stresses exerted …

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Feasibility Studies To Support Landfill Gas Recovery In Ghana, Neda Jangikhatoonabad Jan 2015

Feasibility Studies To Support Landfill Gas Recovery In Ghana, Neda Jangikhatoonabad

Civil Engineering Theses - Archive

According to World Bank Ghana generates 0.09 kg of solid waste per person per day, where there are only 4 engineered landfills in the country. In 2010, Ghana contributed to 0.13% of global greenhouse gases emissions, 10% of which was associated with waste sector. On the other hand, according to the World Bank in 2011, 39.5 % of Ghana’s population did not have access to electricity. Tapping landfill gas will not only provide portion of needed energy for the country, but will also help solve many of the environmental problems. Currently there is no landfill gas to energy project in …

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Using Lean Techniques To Reduce Waste And Improve Performance In Municipal Project Delivery, Yasir E. Abdelrazig Jan 2015

Using Lean Techniques To Reduce Waste And Improve Performance In Municipal Project Delivery, Yasir E. Abdelrazig

Civil Engineering Theses - Archive

The basic concepts of lean thinking in construction projects are to reduce waste, improve communication, and promote teamwork integration through a common set of tools and techniques. With increased demand for public works projects, there is a need to focus attention on the efficient delivery of construction project services in the public sector, and in particular, on municipal project delivery. Performance improvements using lean techniques are considered to overcome problems, facilitate project progress, and offer recommendations for better municipal construction project processes. Municipal projects are a part of the public works which include a broad category of infrastructure projects, financed …

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A Parametric Study Of The Effects Of Ɛ And ��̅ On The Poisson Boltzmann Equation For One And Two Spherical Particles Using A Boundary Integral Equation Method, Oumama H. Lingamfelter Jan 2015

A Parametric Study Of The Effects Of Ɛ And ��̅ On The Poisson Boltzmann Equation For One And Two Spherical Particles Using A Boundary Integral Equation Method, Oumama H. Lingamfelter

Civil Engineering Theses - Archive

Many biomolecules, such as DNA, exhibit properties that are dependent on their electrostatic interaction with an electrolytic solution. Both explicit atomistic and implicit continuum models have been developed to solve the electrostatic problem. The implicit models are based on the Poisson-Boltzmann (PB) equation, whose lower computational cost makes them favored for bio-molecular applications, particularly as the molecule size increases. Among the implicit models, a boundary integral equation (BIE) method involving only numerical treatment on a surface in turn is more efficient than domain-based finite element and finite difference methods. This is especially so in the present case where the electric …

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Comparison Of Post-Tensioned Cast In Place Concrete And Steel-Concrete Composite Bent Caps, Francisco David Berrocal Ruiz Jan 2015

Comparison Of Post-Tensioned Cast In Place Concrete And Steel-Concrete Composite Bent Caps, Francisco David Berrocal Ruiz

Civil Engineering Theses - Archive

Civil engineering projects are conditioned not only by the technology available but also by resources availability as well as budget and construction time. Special conditions applicable to particular projects can also control their development.The correct selection from the different feasible alternatives can determine the final output of a project. In that sense, the importance of bridge structures on both the overall budget and schedule of civil engineering projects makes the selection of the proper structural typology decisive for their success or failure. In some cases, special characteristics can establish the need of innovative solutions to guarantee a successful development of …

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Smart Speed Bumps, Mohammed Shakir Rajani Jan 2015

Smart Speed Bumps, Mohammed Shakir Rajani

Civil Engineering Theses - Archive

The research underscores the need and importance of traffic calming devices and provides the basis for designing and building a device for traffic calming in neighborhoods with high pedestrian traffic, particularly children. The thesis focuses on developing a traffic calming device that is responsive to driver behavior rather than a static traffic calming device. The design presented herein involves modifying conventional speed bumps used for calming traffic in areas with high pedestrian traffic. The relevant engineering issues that are addressed include:* The functional requirements of the overall system and each of the system components* Operational challenges* Testing framework for evaluating …

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Concrete Chloride Ingress: Effect Of Frp Type, Layers And Epoxy, Vinod Reddy Kamagani Kuntla Jan 2015

Concrete Chloride Ingress: Effect Of Frp Type, Layers And Epoxy, Vinod Reddy Kamagani Kuntla

Civil Engineering Theses - Archive

The main objective of this research is to reduce the chloride ingress in concrete due to the effects of Fiber Reinforced Polymer (FRP) type, layers and Epoxy. It has been established from previous researches that FRP wrap used to retrofit concrete structures offer a high resistance to chemical solutions but in this case study different variables like FRP, layers of FRP and only epoxy are used to know the resistance of concrete structures to chemical solutions. The ACI 318-11 Code allows for a reduction of clear cover depth if an equivalent clear cover depth can be establish. The FRP used …

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Development And Validation Of Tdr Based Sensors For Thermal Conductivity And Soil Suction Measurements, Nan Zhang Jan 2015

Development And Validation Of Tdr Based Sensors For Thermal Conductivity And Soil Suction Measurements, Nan Zhang

Civil Engineering Dissertations - Archive

Simultaneous measurement of soil thermal conductivity, moisture content, dry density and soil suction is a challenging issue and very important to the design of geothermal related structures such as geothermal energy piles (GEP), ground source heat pump (GSHP) systems borehole thermal energy storage (BTES) systems, etc. The measurement of these properties is mainly done in laboratory conditions which can be time consuming. Hence, an attempt is made in this research to determine a new field sensor that can provide these properties about time frame. TDR technique had been used successfully to measure soil moisture content and dry density by analyzing …

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