bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Analysis of the Performance of a Parabolic Trough Solar Concentrator System
Authors: Hammad M. , Al-Qtiemat A. , Alshqirate A.
Published: April 2014

The increasing fossil fuel costs have led the world to use the clean and naturally available energy from the sun to produce electric power.

Parabolic trough technology is nowadays the most extended solar system for electricity production or steam generation for industrial processes. It is the most proven, lowest cost and large-scale solar power technology available today. It is basically composed of a concentrator collector field which converts solar irradiation into thermal energy that will be used as input for a Rankine power cycle. In such plants, a storage system can be implemented in order to increase plant production.

This work aimed to conclude with a simulation model of a solar thermal power plant using a parabol solar concentrator. The Euro Trough (ET) Concentrator was used as case study. MATLAB software was used for the analysis and performance evaluation. Different working fluids were used in the simulation which were: Pressurized water, Boiling water and Oil (Therminol-VP1).

It was found that using water (pressurized or boiling) in the receiver tube is better than the Therminol-VP1 oil.

And the pressurized water has the highest value of efficiency compared to the boiling water and Therminol-VP1 oil. The oil using system presented the highest energy losses system, and the lowest efficiencies. The ET performance was tested at different places in Jordan, and the distribution of direct solar irradiance at different days around the year was calculate and exhibited for Ma’an city as a case study. A comparison between simulated results and that found in literature were carried out with observed good conformity.
Observation and Evaluation of Scratch Damage Characteristics of Injection Molded, Rubber Toughened Poly(Methylmethacrylate)
Authors: An Jihun , Kang Byoung-Hyun , Choi Byoung-Ho , Kim Hyoung-Jun
Published: April 2014

Poly(methylmethacrylate) (PMMA) is one of popular engineering polymers for many engineering applications such as glass substitutes, medical applications, electronic goods, optical fibers, laser disk optical media and so on. PMMA is a lightweight material with excellent optical properties and balanced mechanical properties. However, PMMA is commonly blended with various functional fillers, and rubber particles are one of them to improve the low impact toughness of unfilled PMMA comparing with other engineering polymers such as polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) copolymer and so on. PMMA is generally used to make exterior of a commercial product, so scratch characteristics of PMMA is very important in terms of the aesthetic point of view.

In this paper, rubber toughened PMMA plates are prepared by injection molding, and static and progressive scratch tests are performed. Samples are prepared by various injection molding conditions, and two orientations (machine direction and transverse direction) of the injection molded plate are considered for scratch tests. Three scratch damage mechanism stages, i.e. mar/ploughing, whitening and cutting stages, are identified by observing the scratch damages and two critical loads to define the variation of scratch damage mechanisms are recorded to evaluate the scratch resistance of rubber toughened PMMA samples. Scratch damage characteristics are examined by various microscopy techniques such as optical microscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, optical profiler and so on. It is clearly observed that scratch damage characteristics of rubber toughened PMMA are changed sensitively for various test conditions due to rubber particles, so it can be known that the mold design should be carefully optimized to improve scratch characteristics of injection molded rubber toughened PMMA product.
A Study of Urban Electric Bus With Hybrid Energy Storage System Based on Battery and Supercapacitors
Authors: Mapelli Ferdinando Luigi , Tarsitano Davide , Annese Davide , Sala Marco , Bosia Giorgio
Published: April 2014

Nowadays considerable resources have been invested on low emission passenger vehicle both for private and public transportation. A feasible solution for urban buses is a full electrical traction system fed by supercapacitor that can be recharged at each bus stop while people are getting on and off. Such vehicle covers a short distance between consecutive stops, usually less than half a kilometer. An energy storage system able to provide high power peaks and small amount of energy is required. For these reasons, supercapacitors, which are capable of fast charging during bus stops, appear the most appropriate storage devices [1]. In order to consider the worst operating condition for the bus (like traffic jam of higher distance to be covered), a conventional battery is also installed, getting an hybrid energy storage system. An energy management function, able to manage the energy storage system, has been developed and validated by means of a numerical simulation model.
Test Rig Design to Explore Water Droplet Behavior in a Four Stage Axial Compressor
Authors: Clauss S. , Schnitzler J. P. , Barabas B. , Nagabhushan P. S. , Benra F. K. , Dohmen H. J.
Published: April 2014

The efficiency of gas turbine cycles can be enhanced by many applications and combinations according to the choice of the thermodynamic cycle. Gas turbine cycles which operate with humid air and water injection at different locations of the compressor are in the focus of present thermodynamic analysis and experimental research. Reasoned by their high potential in efficiency and power output augmentation, they have been implemented on many industrial gas turbines. The evaporation process of water droplets, especially at high temperature and pressure levels has been recently investigated with the laser based measurement technique Phase Doppler Particle Analyzer (PDPA) in detail in a stationary test rig at the University of Duisburg-Essen. The focus of these investigations was on the analysis of the evaporation process in a free stream or cross flow without droplet wall interaction [1–5]. In this paper the development of a novel four stage axial compressor test rig which is designed for water injection will be introduced and results of numerical investigations will be presented. This test rig has been designed to adopt the results from the stationary test rig to a real compressor.

The first part of the paper deals with the mechanical and aerothermodynamic design of the test rig. Certain design parameters, the optical access for the PDPA measurements and a comparison between numerical and experimental results without water injection are outlined.

In the second part of the paper, first comparative results from numerical investigations of the compressor performance in dry and wet compression operating conditions are presented. Furthermore, numerical results for droplet wall interaction in the four stage axial compressor are shown. This analysis outlines the need for further experimental research in the future to validate numerical methods with accurate droplet wall interaction behavior in turbomachines.
Combining Product Innovation With Service Innovation to Increase Value Created With a System
Authors: Ritola Tuomas , Coatanéa Eric
Published: April 2014

The focus in the businesses of manufacturing and selling technological devices has been increasingly shifting from USA and Europe towards Asiatic countries due to cost-effectiveness and lower costs of resources. In the areas where costs are inevitably higher, new measures have to be considered in order to be able to compete in the global economy. In this article, we study how can we utilize combined benefits of technological and service innovations in competing against the traditional product-oriented offerings. Product-service systems are integrated systems of products and services that create value through use for customers; the hypothesis in this article is that the efficiency of the business network can be increased by designing an integrated product-service system in comparison to the product-oriented approach. The hypothesis is studied via a real-life product-service system design case study of an automated recycling system, and system dynamics simulation is used to analyze the value created with the system in the related business network. In theory, product-service systems have many potential benefits in comparison to product-oriented offerings; identifying the benefits in practice in a case study increases the understanding of product-service systems design and facilitate their application in the industry.
Trigonometric Collocation for Computation of Steady State Response of a Cracked Beam
Authors: Bakeer Bakeer , Shiryayev Oleg
Published: April 2014

Development of vibration-based structural health monitoring techniques requires the use of various computational methods to predict dynamic responses of damaged structures. The method described in this work can be used for prediction of steady state harmonic responses for structures with fatigue cracks and may have several advantages over alternative techniques.

The method appears to be relatively easy to implement and computationally inexpensive. The steady state response of the system at a given number of time points distributed over one vibration period is represented in terms of Fourier series containing higher frequency harmonics. Equations of motion are formulated in the form that allows for easy computation of Fourier coefficients for all terms in the series. Iterative procedure is used for determining the time of stiffness change in order to capture bilinear dynamic behavior. We present results of initial investigation by applying the method to a model of a cantilever beam with a crack.
Thermal Tomography Using Experimental Measurement Data
Authors: Toivanen Jussi M. , Kolehmainen Ville , Tarvainen Tanja , Huttunen Janne , Savolainen Tuomo , Orlande Helcio R. B. , Kaipio Jari P.
Published: April 2014

Experimental measurement data is used to test the feasibility of thermal tomography. The 3D distributed thermal conductivity, heat capacity and surface heat transfer coefficient of a mortar target containing an air hole are estimated using measurement data obtained with a prototype thermal tomography measurement device.
Sustainability-Driven Tolerancing and Design Optimization of an Aircraft Engine Component
Authors: Hoffenson Steven , Forslund Anders , Söderberg Rikard
Published: April 2014

Design for sustainability requires decision-makers to simultaneously consider the economic, ecological, and social consequences of their products and production processes for a broad range of stakeholders. While some choices may mutually benefit the three sustainability categories, there are often tradeoffs where improving one objective comes at a cost to another. Previous studies have shown that geometric tolerance decisions can affect all three sustainability criteria and create tradeoffs, particularly when they are made in conjunction with other design decisions. This paper presents a framework for analyzing product design decisions through a multi-objective optimization approach to sustainable design, tailored to the application of an aircraft engine turbine component. Models are constructed for production and maintenance costs, ecological impacts from manufacturing and use, and social impacts from neighborhood noise and delays caused by reliability-based maintenance events. Using advanced computational simulation and optimization, tradeoffs are shown and sustainable decision-making strategies are discussed.
Identification of Dynamics of Surface Suction Over an Airfoil at Low Reynolds Numbers
Authors: Chawla Jasvipul S. , Suryanarayanan Shashikanth , Sheridan John , Falzon Brian G.
Published: April 2014

This paper deals with identification of dynamics in suction control of airfoils for low Reynolds number regimes (8 × 104 – −5 × 105). In particular, the dynamics of interest is the map that relates suction pressure and surface pressure. Identification of such dynamics is of use to a variety of active control applications including suction control in small/medium wind turbines which operate in these Reynolds number regimes. Prior research has largely focussed on higher Reynolds number regimes, creating a need for such a study. The dynamic relation between suction and surface pressure was identified as an overdamped second order system.
Boundary Layer Measurements on a Rotating Disk
Authors: Raghav Vrishank , Komerath Narayanan
Published: April 2014

Dynamic stall occurs on helicopter rotor blades, wind turbine blades, and even insect and bird wings. Although most studies on dynamic stall are conducted assuming two-dimensional behavior, it has been shown that this phenomenon is highly three-dimensional. Recent studies of dynamic stall on a rotating blade of helicopter in forward flight and wind turbines in yaw have shown that the nature of the radial flow near the surface has first-order significance in the stalled flow field. Past literature suggests that the boundary layer over a rotating disk has been correlated to that over a swept wing. Drawing a similar parallel it is hypothesized that fundamental insights into dynamic stall may be derived from studying the boundary layer over a rotating blade in dynamic stall is similar to that over a rotating disk. Particle image velocimetry (PIV) is used to investigate the boundary layer development on a rotating disk. The first set of measurements was conducted using PIV with a micro lens attachment to the camera. Next, a microscope was used to conduct μ-PIV measurements. The measured radial velocity profiles show substantially higher radial jet peak velocities than the analytical solution for a mirror-smooth disk. This difference is narrowed down to the effect of surface roughness of the painted disk, representative of reality on rotor blades used in PIV. This results in a much higher effective viscosity in the near-surface layer, contributing to additional radial flow, as seen from the centrifugal pump literature. However, the non dimensional radial velocity profile exhibits the expected self similar behavior at various radial locations.
A Hybrid Geothermal-Solar Power System: Optimal Design and Operation
Authors: Ghasemi Hadi , Mitsos Alexander
Published: April 2014

A model is developed for an existing plant with an organic Rankine cycle (ORC) utilizing a low-temperature geothermal brine. The model includes the performance characteristics of the ORC components. Since the size of turbines in this ORC is over-designed for available geothermal energy source, the model is reconfigured to switch the number of functioning turbines in the ORC. At a given ambient temperature, the configuration with the maximum output power is chosen as the optimal configuration. The model is validated with a set of 7200 measured data collected from one-year operation of the plant. The measured data include the net output power of the ORC as a function of ambient temperature ranging from −15 to 37 °C. The operation of the ORC is optimized maximizing the net output power of the system. The developed model is used as a basis for development of a hybrid geothermal-solar system. A hybrid geothermal-solar system in solar heating mode is analyzed and optimized. The geothermal stream has the potential to provide up to 240 MW thermal energy to the ORC and the heat transfer rate of the solar system to the cycle at nominal time is 17.6 MW. A hybridization strategy is developed that achieves a significant boost in the net output power of the system compared to the geothermal ORC. The enhancement by this approach ranges from 10%–40% as an increasing function of ambient temperature. At low ambient temperatures (Tamb ≤ 1.66 °C), two recuperators are required to be included in the hybrid system to satisfy the lower bound on temperature of geothermal brine (GB).
Preparation of Elastic Bipolar Plate for Polymer Electrolyte Fuel Cells
Authors: Lee Jae-Young , Choi Bumchoul , Lee Woo-Kum , Shim Joong-Pyo , Lee Hong-Ki
Published: April 2014

Highly conductive bipolar plate for polymer electrolyte membrane fuel cell (PEMFC) was prepared using phenol novolac-type epoxy/graphite powder (GP)/carbon fiber filament (CFF) composite, and a rubber-modified epoxy resin was introduced to the phenol novolac-type epoxy resin in order to give elasticity to the bipolar plate. The cure condition of the neat epoxy system, differential scanning calorimetry (DSC) was carried out and the DSC data were introduced to Kissinger equation. And tensile and flexural tests were carried out using universal testing machine (UTM) and the surface morphology of the fractured specimen and the interfacial bonding between epoxy matrix and CFF were observed by a scanning electron microscopy (SEM). Kissinger expression showed that the activation energy for the cure kinetics of novolac epoxy (9.3g)/rubber epoxy (1.0g)/curing agent (9.6g)/accelerator (0.1g) system was 76.8 kJ/mol and the pre-exponential factor was 1.73 × 1010 min−1. As was expected, electrical conductivity increased with increasing total carbon content, and the value increased with increasing CFF content at the same carbon content. Tensile strength and flexural strength linearly decreased with increasing epoxy content, however at the same carbon content, these values increased with increasing CFF content. It was because the CFF acted as electrical conductive pass and the good effect on the mechanical properties was due to the strong bonding between CFF and epoxy resin, which was confirmed by the SEM.
Synthesis and Experimental Investigation of Rheological Behavior of EG and Water Based hBN Nanofluids
Authors: Kurt Melike , Ertürk Hakan , Atalık Kunt
Published: April 2014

Hexagonal boron nitride (hBN) is a ceramic material with high thermal conductivity and superior chemical stability that makes it a suitable candidate for nanofluid synthesis. The studies that focus on hBN nanofluids are mostly limited to hBN-oil dielectric nanofluids. However, using hBN with other base fluids has also significant potential applications. This study focuses on stability and rheological behavior of hBN-water and hBN-ethylene glycol nanofluids that have not been investigated in detail. Nanofluids with hBN nanoparticles of an effective diameter of 70 nm are synthesized using the two-step method. The main problem in this method is sedimentation as a result of disproportionate amount of clustering of nanoparticles within the nanofluids. In the preparation procedure of nanofluids, sonication and pH level control are used. The stability of the hBN-water nanofluids is determined either by quantitative methods such as zeta potential measurements and/or effective particle size measurements via dynamic light scattering, or qualitative methods such as SEM (Scanning Electron Microscopy) and STEM (Scanning Transient Electron Microscopy). Following the investigation of the effect of several parameters, such as sonication time, pH level of the suspension on the stability of the nanofluids, rheological behavior is investigated experimentally. Rheology experiments are conducted with a cone–plate rheometer. In these experiments different volume concentrated (0.5–1%) nanofluids are considered. Validation studies for preparation and characterization methods are carried out with alumina (Al2O3), nanofluids which are synthesized by dispersing γ-Al2O3 nanoparticles of 15 nm into deionized water.
Optimized Multi-Floor Throughflow Micro Heat Exchangers
Authors: Abdoli Abas , Dulikravich George S.
Published: April 2014

Multi-floor networks of straight-through liquid cooled microchannels have been investigated by performing conjugate heat transfer in a silicon substrate of size 15×15×1 mm. Two-floor and three-floor cooling configurations were analyzed with different numbers of microchannels on each floor, different diameters of the channels, and different clustering among the floors. Thickness of substrate was calculated based on number of floors, diameter of floors and vertical clustering. Direction of microchannels on each floor changes by 90 degrees from the previous floor. Direction of flow in each microchannel is opposite of the flow direction in its neighbor channels.

Conjugate heat transfer analysis was performed by developing a software package which uses quasi-1D thermo-fluid analysis and a 3D steady heat conduction analysis. These two solvers are coupled through their common boundaries representing surfaces of the cooling microchannels. Using quasi-1D solver significantly decreases overall computing time and its results are in good agreement with 3D Navier-Stokes equations solver for these types of application.

Multi-objective optimization with modeFRONTIER software was performed using response surface approximations and genetic algorithm. Maximizing total amount of heat removed, minimizing coolant pressure drop, minimizing maximum temperature on the hot surface, and minimizing non-uniformity of temperature on the hot surface were four simultaneous objectives of the optimization. Pareto-optimal solutions demonstrate that thermal loads of 800 W cm−2 can be effectively managed with such multi-floor microchannel cooling networks. Two-floor microchannel configuration was also simulated with 1,000 W cm−2 uniform thermal load and shown to be feasible.
Product Life-Oriented Development of Component Commonality and Variety
Authors: Eilmus Sandra , Krause Dieter
Published: April 2014

To reach many customers and have a broad range of products at marketable prices companies aim for high commonality across product variants. Commonality is known as the sharing of components by product variants. But using the same components for different product variants can also lead to trade-offs in product function and fulfillment of customer requirements as well as in internal processes. The aim of this paper is to investigate by literature review and a case study on forklift trucks how benefits and trade-offs can be balanced according to corporate needs. Existing tools from the Integrated PKT-Approach for Developing Modular Product Families are applied and advanced in the case study. Practical examples demonstrate that commonality is a gradual property that can be given to variant components as well and that it is influenced by the modular structure and how components are handled as modules in different life phases. New product concepts with enhanced commonality are derived and evaluated by estimating the created lot size caused and code number caused costs.
Enhancing Infeasibility Detection Method for Mechanical Design Problems
Authors: Khorshid E. , Falah A.
Published: April 2014

This paper presents the application of the Multistart point technique in order to enhance a previous existing infeasibility detection method based on Sequential Quadratic Programming (SQP) used for detecting modeling errors by finding the Minimum Intractable Subsystem (MIS) of constraints. This new method showed a great potential in detecting infeasibility without countering the problems of the initial starting point faced by many methods for Nonlinear Programming Problems. The real performance of the anticipated method is demonstrated by solving complex mechanical systems were inconsistency constraints are presented. The proposed method succeeded to find the MIS set of constraints that cause infeasibility in the these models while direct Nonlinear Programming solver, based on Sequential Quadratic Programming only, failed to detect the correct inconsistent constraints.
A Teaching Strategy for Advanced Manufacturing Courses
Authors: Ahmad Basel Alsayyed
Published: April 2014

In this paper, the author presents an experiment for teaching advanced manufacturing courses with the objective to maximize the learning experience based on course outcomes. A CAM course was selected to run the experiment on the students in two male sections and two female sections. The course’s outcomes were drafted based on the mechanical engineering program’s objectives. Their focus is on fulfilling as many of the program outcomes as possible. The level of fulfilling a program objective by a course outcome is then also monitored. The strategy focuses on increasing the hands on experience of the students as well as introducing more computer and technology content in the course. Every activity will be evaluated quantitatively and qualitatively. Based on the progress in a regular semester, the students’ performance is monitored and a calibration of theory versus practical experience is done accordingly. Initial results reveal that the sooner the practical part of the course is introduced the better the results will be for both understanding the practical as well as the theoretical part of the course.
Development of the PIRT for the Small-Break Loss-of-Coolant Accident With High Pressure Injection Failure
Authors: Kinoshita Ikuo , Yamada Minoru , Torige Toshihide , Murase Michio , Yoshida Yoshitaka
Published: April 2014

In order to improve the reliability of using the accident management procedure “low pressure injection by intentional depressurization of the steam generator secondary side” in a small-break loss-of-coolant accident (SBLOCA) with high pressure injection (HPI) failure, the statistical safety evaluation method is applied to the thermal hydraulic analysis of this event. The cornerstone of this method is the development of the phenomena identification ranking table (PIRT). In this paper, the PIRT was developed for the SBLOCA with HPI failure in a conventional PWR plant. The safety evaluation parameter was the peak cladding temperature (PCT). In the PIRT development, the phenomena identification was conducted by dividing the event progression into five phases: blowdown, natural circulation, loop seal, boil-off, and core recovery. As a result, 24 important phenomena were extracted in the PIRT, and the reasons used for ranking of these phenomena were described extensively. In addition, sensitivity analyses using the RELAP5/MOD3.2 code were performed for the most important phenomena. Uncertainty of the analytical models of the three phenomena: “uncovered core heat transfer”, “CCFL at the inlet of the U-tubes”, and “critical flow of the break” had a large influence on the predicted PCT. Therefore it is important to investigate separate effect tests for these phenomena thoroughly in order to prevent the model uncertainty distributions from being extended excessively.
Numerical Analysis on Stress Induced Corrosion With Emphasis on Ti-Alloy Total Hip Arthroplasty Stem Failure
Authors: Paliwal Manish
Published: April 2014

Modular designs give orthopaedic surgeons a greater flexibility to custom fit the implant to the patients bone while performing total hip arthroplasty. Titanium alloy (Ti6Al4V (ASTM F-136)) is typically used for modular hip implant stems. This highly corrosion resistant alloy forms passive surface oxide films spontaneously. However, with modular designs, micro-motion may occur at the taper junctions during mechanical loading. Crevices between the taper junctions may allow the body fluids to enter and remain stagnant. These conditions make the modular tapers susceptible to fatigue and mechanically assisted crevice corrosion. The in vivo degradation of metal alloy implants compromises the structural integrity. The influence of stress induced corrosion and pitting leading to the in vivo catastrophic failure of a titanium-alloy modular implant in cementless total hip arthroplasty was numerically investigated. The effect of pit geometric parameters are discussed in terms of taper performance.
Experimental and Computational Investigation of the Drag of a Towed Hydropower Turbine
Authors: Bryan G. T. , Platzer M. F. , Kwon Y. W.
Published: April 2014

In a previous paper (IMECE2011-62311) Platzer et al proposed the use of sailing ships equipped with hydropower turbines to generate the electricity required for the production of hydrogen and oxygen by means of electrolysis which then is brought back to land for re-conversion into electric power. A crucial aspect of the practicality of this “energy ship” concept is the drag of the hydro-turbines. Since little information exists about the drag of towed hydropower generators in this paper the drag of a small hydropower turbine was investigated in a towing tank. Drag measurements are presented for a speed range between 0.6 and 1.8 m/s. Comparisons with available data and the predictions by a computational fluid dynamics analysis show good agreement.
Vibratory Stress Suppression in Turbine Blades Subjected to Aerodynamic Loading
Authors: Aziz Imran , Tarar Wasim , Akhtar Imran , Azam M. Nadeem
Published: April 2014

Vibratory stresses are the main cause of failure in gas turbine engines and other rotating machinery components. These stresses must be attenuated to an acceptable level through an efficient process in order to prevent failures in turbine blades. Research [8] has shown that a thin magneto mechanical coating layer can make a significant contribution to the damping and reduction of these vibratory stresses. Previous studies on analyzing the damping characteristics of these coatings for various applications, such as beams and turbine blades, employed general solid mechanics loads. In this study, we numerically compute aerodynamic loads on one and a half stage axial turbine in order to bring more reality to the problem. We employ a three-dimensional finite-volume based solver to simulate the flow in the turbine using SST model to account for turbulence effects. Sliding mesh technique is used to allow the transfer of flow parameters across the sliding rotor/stator interfaces. In order to model a single passage configuration, profile transformation method is used. A free vibration analysis has been performed to obtain natural frequencies and corresponding mode shapes to analyze resonance conditions. The computed CFD loads are then applied to an uncoated and coated turbine blade through a finite-element analysis (FEA) package. A forced response analysis is performed at the critical frequencies to obtain vibratory stresses. Numerical results show suppression of vibratory stresses at various low and high frequency vibration modes. The results are benchmarked against published data and closely match the expected outcome. The research presents an effective procedure for suppression of vibratory stresses in gas turbine engine component subjected to real world aerodynamic loading. The new procedure is a significant improvement towards more realistic simulation based solutions for vibration suppression problems.
Tailored Polyurea-Glass Interfaces and the Characterization by the Single-Fiber Fragmentation
Authors: Jia Zhanzhan , Rawal Ravish , Isaacs Jon , Nemat-Nasser Sia
Published: April 2014

Polyurea is an elastomer that has been intensively researched due to its excellent thermal and mechanical properties. Polyurea based composite material has recently become a research interest to further explore what this polymer has to offer. In order to better understand the overall static or dynamic mechanical properties of the polyurea based composites, how to tailor and characterize the polyurea-filler interface has become a crucial problem. This study focuses on one of the filler materials, glass. Three types of polyurea-glass interfaces are studied by using silane reagents that have similar molecular structures but with different end functional groups to modify the glass surfaces. Accordingly, bonds with different strengths are formed between the glass and the polyurea through the different chemical character of the reagent molecules. The polyurea-glass interfacial properties are tested by the single-fiber fragmentation, which is a widely used method to test the shear properties of the interface between the fiber and the polymer. Single-fiber fragmentation samples are fabricated by casting a single glass fiber along the axial direction of the dogbone-shaped polyurea tension test sample. Tension tests are conducted and the continuous photoelastic videos are taken to observe the single fiber fragmentation process until the fragmentation reaches its saturation state. Meanwhile, stress-strain data are recorded. By analyzing the single-fiber fragmentation data, the polyurea-glass interfacial shear strengths are calculated. The observation of the debonding zones at the interface is used to find the approximate models for the interfacial shear adhesion of polyurea-glass interfaces for different reagents, hence proving the potential for tailoring of the interfacial strength using surface treatment.
Streamline Analysis Method to Determine Force Loading on Axial Compressor Blades
Authors: Patel Ami , Ribando Robert , Untaroiu Alexandrina
Published: April 2014

Within the field of rotor dynamics, the aerodynamic loading on turbomachinery blades is an important factor for calculating the overall stability of these machines. In order to determine the magnitude of this force, it is necessary to analyze the flow of the fluid through the turbomachinery. With respect to modern jet engines, an axial compressor is the component through which the incoming air passes first. As the performance of the compressor often determines the efficiency of the overall engine, it is crucial to analyze and understand the fluid effects in the compressor properly. Therefore, the goal of this study is to determine the aerodynamic forces on the blades of axial compressors in jet engines for further use in rotor dynamic calculations. To avoid a time consuming and computationally expensive procedure, a two-dimensional “streamline” or “through-flow” analysis is adopted, in which various assumptions are used to simplify the Navier-Stokes equations. For the streamline model, the flow between blades is divided into “annuli”, and fluid properties are calculated from hub to casing while marching axially downstream through the multiple stages making up the compressor. This study uses a coded version of the streamline analysis method written in Matlab. Computational results are then compared with experimental values provided by industry, which are evaluated with respect to the total pressure ratios and temperature ratios across the compressor stages. Validation cases were run using experimental data made available in the literature by NASA. Cases studied include a single-stage rotor case called Stage 37, and a multistage compressors case called NASA 74A.
Study of Microstructure and Mechanical Properties of Yttrium Stabilized Zirconia Coating Deposited by Air Plasma Spray
Authors: Leither Chris P. , Roy Lauren E. , Azarmi Fardad , Tangpong X. W.
Published: April 2014

Ceramic materials have been used extensively in different industries due to their excellent properties in high temperature environment. Thermally sprayed ceramic coatings offer outstanding properties which make them suitable candidate for advanced applications. These coatings exhibit excellent wear resistant properties with high adhesion strength. Depending on the application, ceramic coatings can be subjected to in-plane or out-of-plane loading during service. When the components are exposed to extreme change in temperature, consistent expansion, and shrinkage of the materials will cause crack initiation and propagation, resulting in spallation of the coating and consequently failure of the components. In this study, mechanical performance of plasma sprayed Yttrium stabilized Zirconia coating was investigated. A powder mixture of Yttrium stabilized Zirconia (ZrO2−8Y2O3) was air plasma sprayed on a cast iron substrate. Microstructural characterization of the as-sprayed coating was performed to evaluate the microstructural uniformity of the deposited samples using scanning electron microscopy (SEM). Three-point bend tests were performed to measure bending modulus of the free standing as-sprayed coating samples. Knoop indentation technique was also used as an alternate method to determine the modulus of the coating. Damping properties of the samples were also evaluated. This study pays special attention to the dependency of the mechanical performance on the microstructural characteristics of the thermal sprayed ceramic coatings.
Comparative Study Between FEA-Based Sequentially-Coupled and Fully-Coupled Thermal Stress Models in a Laser Hardening Process
Authors: Ghosh Suhash , Sahay Chittaranjan , Connors Joseph
Published: April 2014

Numerous mathematical investigations of laser transformation hardening process have been conducted in the past three decades. The commonly used strategy of a sequentially coupled temperature-stress analysis is to first obtain temperature results from the temperature elements in a thermal loading model, followed by the calculations of thermal stresses from the structural elements under structural loading. Temperature is used as a predefined variable (varies with position and time only) as it is assumed to not change by the stress analysis. Fully coupled thermal-stress analysis is needed when the stress analysis is dependent on the temperature distribution and the temperature distribution depends on the stress solution This paper compares these two finite element (FE) based approaches for modeling temperature and thermal stress evolution in laser transformation hardening of hypoeutectoid steels. The dependence of temperature results on stresses and vice versa at higher temperatures involving significant inelastic strains has been demonstrated. Preliminary investigation reveals that under such circumstances thermal and mechanical solutions must be obtained simultaneously rather than sequentially.
Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications
Authors: Besarati Saeb M. , Goswami D. Yogi
Published: April 2014

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose, however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.
Strain Sensing of Glass Fiber Reinforced Coupons by Using Carbon Nanotube Doped Resin
Authors: Vairis Achilles , Alexopoulos Nikolaos D. , Favvas Evangelos P. , Nitodas Stefanos
Published: April 2014

Addition of different percentages of multi-wall carbon nanotubes (MWCNTs) on the mechanical behaviour of epoxy resin as well as glass fiber composite with symmetrical stacking sequence is assessed. GFRPs were manufactured with the vacuum assisted resin infusion (VARI) process. Performed tensile tests showed that the addition of the CNTs increased the modulus of elasticity with a simultaneously dramatic ductility decrease. The real merit of the CNT addition is the enhancement the composites multi-functionability; piezo-resistivity was recorded to further exploit the self-sensing ability of the innovative composites.
V-Learn-Fact: A New Approach for Teaching Manufacturing and Design to Mechanical Engineering Students
Authors: Kesavadas Thenkurussi
Published: April 2014

Students in the mechanical engineering curriculum are rarely given opportunities for direct experience in the topics in many areas. This is especially true for the education component of the manufacturing and design curriculums. Some reading and stylized laboratory and group projects often substitute for real experience. In this paper an innovative experiential learning curriculum called Virtual Learning Factory (V-Learn-Fact) is described for teaching manufacturing and design courses. In the V-Learn-Fact curriculum, the entire class takes part in a single large project, which covers product realization from concept to final production stage. V-Learn-Fact was implemented in MAE464/564 – Manufacturing Automation course (senior elective and graduate level course) between 2006–2012. A student survey was carried out to gauge effectiveness of this curriculum. 89% of the students fully or partially agreed that the V-Learn-Fact helped them learn topics in manufacturing automation better than traditional mechanical engineering courses. Written comments also provided interesting insights.
Concurrent Spatial Mapping of the Elasticity of Heterogeneous Soft Materials via a Polymer-Based Microfluidic Device: A Preliminary Study
Authors: Gu Wenting , Cheng Peng , Hao Zhili
Published: April 2014

This paper presents a preliminary study on achieving concurrent spatial mapping of the spatially-varying elasticity of heterogeneous soft materials via a polymer-based microfluidic device. Comprised of a single compliant polymer rectangular microstructure and a set of electrolyte-enabled distributed resistive transducers, this device is capable of detecting continuous distributed loads. Through pressing a specimen against the device by a rigid probe with precisely-controlled displacements, the spatially-varying elasticity of a specimen is captured by continuous distributed loads acting on the device and is further registered as discrete resistance changes at the locations of the transducers in the device. Concurrent spatial mapping is conducted on homogeneous and heterogeneous specimens, and the related data analysis is performed on the measured results to extract their elasticity. The obtained results demonstrate the feasibility of concurrent spatial mapping of the spatially-varying elasticity of heterogeneous soft materials via this polymer-based microfluidic device.
Spin Photovoltaic Effect on Molecule Coupled Ferromagnetic Films of a Magnetic Tunnel Junction
Authors: Tyagi Pawan
Published: April 2014

Economical solar energy harvesting can be boosted by the discovery of fundamentally new photovoltaic mechanism, and a suitable system to realize it with commonly available materials. One promising route is to focus on spin property of the electron, not charge, and develop spin photovoltaic effect with widely available ferromagnetic metals like iron and nickel. This paper reports the observation of photovoltaic effect on the molecular spintronics device composed of a magnetic tunnel junctions (MTJ) testbed and organometallic molecular clusters (OMCs). Our MSDs were produced by bridging the OMC channels between the ferromagnetic films of a prefabricated MTJ testbed with exposed side edges. The MTJ testbed exhibited OMC induced strong increase in exchange coupling and photovoltaic effect. Control experiments on isolated ferromagnetic films, same as utilized in the MTJ testbed, suggested that OMCs neither affected the magnetic properties nor produced any photovoltaic effect. Photovoltaic effect was only observed on the pair of ferromagnetic films serving as magnetic electrodes in a MTJ. Our recent Monte Carlo simulations and multiple magnetic characterizations provide evidence that molecules induced strong coupling between two ferromagnetic films can dramatically alter the overall magnetic properties of a MTJ; presumably making an ordinary MTJ suitable for spin based photovoltaic effect. The photovoltaic effect on our molecular spintronics devices (MTJ+OMCs) was sensitive towards the external magnetic field and temperature. Present paper motivates further studies to understand the spin photovoltaic effect in molecular spintronics devices.
Using an Inorganic Aqueous Solution (IAS) in Copper and Aluminum Phase Change Heat Transfer Devices
Authors: Yao Qi , Stubblebine Mike , Reilly Sean , Amouzegar Ladan , Catton Ivan
Published: April 2014

A novel Inorganic Aqueous Solution (IAS) is shown to have a better thermal performance than water when used as the working fluid in copper or aluminum made heat transfer devices. The effect of each chemical in the IAS and how it benefits heat transfer performance for different materials is explained. It was found that the IAS fluid reacts with copper and coats the surface with a layer of hydrophilic products during the initial boiling process. The surface roughness and wettability were increased which led to an enhanced heat transfer performance. The IAS passivates aluminum surfaces and makes water compatible for use with aluminum heat transfer devices. In addition, IAS has potential to improve the heat transfer performance by 50% lower the superheat when used with non-reactive material heat transfer devices.
Dynamics of Viscous Droplets Falling Towards Micro-Patterned Solid Surfaces
Authors: Beussman Kevin M. , Wang Yechun , Lim Wei Y. , Zhou Qixin
Published: April 2014

The interaction between droplets and solid surfaces is of great importance in industrial applications, biochemical processes, and fundamental material research on surface wettability. In this work, a three-dimensional spectral boundary element method has been employed to investigate the dynamics of a viscous droplet falling under gravity influence to micro-patterned solid surfaces. The dynamics of the droplet are investigated under the influence of the Bond number and the topological features of the substrate.
Numerical Simulation of Biodiesel Production Using Waste Cooking Oil
Authors: Mohiuddin A. K. M. , Adeyemi Nabeel Adedapo
Published: April 2014

The goal of this work was to carry out transesterification using computational fluid dynamics (CFD) method and obtain yield comparable to experimental values. First of all, the single–phase flow field was simulated and compared with experimental data obtained by means of particle image velocimetry (PIV) measurements. The velocities calculated from the RSM approach agreed quite well with those from PIV. The CFD simulations of biodiesel production were performed using the Reynolds stress model (RSM) coupled with the eddy dissipation model (EDM). CFD analysis of biodiesel yield compared fairly well with the experimental results available.
Study of Solar Ejector Refrigerant System Using Refrigerant R717 in Office Building
Authors: Zheng Hui-fan , Fan Xiao-wei , Liu Hong-chao
Published: April 2014

A detailed simulation program calculating the performance of solar ejector refrigerant system for comfort air conditioning was presented in this paper. Based on the climatic conditions of xi’an region, the performance of a solar ejector refrigerant system for office building has been analyzed using R717 as refrigerant, the results show that the coefficient of performance (COP) of the system decline in time sequence, and the average COP about the specific days from May to August can arrive to 0.22, 0.12, 0.11, and 0.14. In addition, it is found that solar ejector refrigerant system can provide 13% to 83% heat cooling that the office building needed when the evacuated tube solar collector is 500m2 in xi’an specific days from May to August. The simulation method and results are both a useful reference for the design of solar ejector refrigerant system in xi’an region.