bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Absorption on Solar Energy Collection in Solid Structure
Authors: Huang Yong , Gao Qing , Liu Yan , Yan Y. Y.
Published: May 2012

The application of seasonal solar energy usually needs a convenient thermal collection system attached to the engineering. The study of solar energy collection in solid structure was to explore available methods and assess to the possibility of renewable energy generation being exploited within the highway network. The solid structure, like road, building wall and envelop as solar collector has been being considered to be an effective way using renewable energy. This paper focused on the characteristics of temperature in four structures, such as asphalt, red brick, composite cement and concrete road slab under the solar radiation. Furthermore, the collecting heat based on a hydronic system was investigated experimentally. As to four structure slabs, their temperature differences of absorbing solar radiation varies greatly. The asphalt slab gets the highest temperature and the weakest reflection among them. Comparing others, the asphalt slab is higher by 8.1%, 14.9% and 16.4% respectively than brick, composite cement and concrete. The reflection intensity growth ratio was defined and it can denote the growth potential for absorbing radiation from the solid slab surface. From experiments, it is clear that a suitable selection of road materials can produce a great effect to improve thermal absorption, conduction and penetration in the solid slab.
Uncertainty of Thrust Prediction for a Small Demonstration Turbojet
Authors: Perez-Blanco H. , Kunkel D.
Published: May 2012

A small turbojet, the SR-30, is often used in academic settings to demonstrate thrust generation. The experience and insights afforded by this type of experimentation we find invaluable, because the students appraise a turbojet, from start-up to wind down, in all its dimensions: from basic thermodynamics to creep considerations, passing through instrumentation and lubrication. Experimental uncertainties of measurements taken on this unit lead to conflict with basic thermofluids laws, and have been reported in the literature. The present work introduces a thermodynamic model whereby the thrust can be calculated for a range of speeds. The model resorts to conservation principles and efficiencies to factor in the turbine irreversibilities. Six significant variables are assigned uncertainties, and a thrust distribution is generated via a Monte-Carlo analysis. The parameters of the thrust distribution are analyzed to determine the reliability of thrust predictions. Intermediate cycle temperatures can be estimated via an approach consistent with the thermo-fluids laws.
Experience in Teaching Turbomachinery Using Advanced Dedicated Software
Authors: Perez-Blanco H. , Rigg A. , Moroz L.
Published: May 2012

Whereas turbomachinery design has evolved over the last two decades, updating instruction on the topic to reflect the new prevailing methods and techniques remains a challenge. Part of this challenge stems from the diversity of technologies covered in the courses; part of it ensues from the extensive use of software by industry designers. A review of the literature shows that varying degrees of complexity in software have been adopted for teaching, and that numerical experimentation has in some universities replaced laboratory experimentation. This paper describes the experience and outcomes of teaching turbomachinery to senior engineering students using advanced design software. The cases and results analyzed by the students for axial compressors and turbines are discussed, and the results of the effort are evaluated from the somewhat different perspectives of the students and of the instructor. Whereas the use of the program must be viewed in the context of the entire course (two hardware labs are held along with conventional lectures and homework), the use of design software could be seen to multiply the skills of the students, enabling broad 3-D design considerations and visualization seldom possible otherwise. In addition, an understanding of prevailing stresses is initiated with the software.
Transient Response of Strain Rate Dependent Composite Plates Using Finite Difference Method
Authors: Shokrieh M. M. , Karamnejad A.
Published: May 2012

In the present work, the response of laminated composite plate under dynamic loading is investigated using a macro-mechanical approach by use of a finite difference model which accounts for geometric nonlinearity and strain rate effects. Coupled nonlinear equations of motion of a laminated plate based on classical laminated plate theory (CLPT) and first-order shear deformation laminated plate theory (FSDT) are derived and reduced to nonlinear ordinary differential equations in time domain by finite difference approximations for displacements. Newmark time integration scheme in association with Newton-Raphson iteration method is applied to solve the system of nonlinear equations. Sudden material property degradation rules are modified to account for strain rate effects. A progressive damage model is developed based on the modified material property degradation rules and Hashin-type failure criteria and added to a finite difference model. The model is implemented into a computer code in Mathematica 6. The model is validated by comparison of the present results with those are available in the literature. The effects of transverse shear strain are studied by comparison of the results obtained using CLPT and FSDT. In order to investigate the strain rate effects, a clamped Glass/Epoxy composite plate subjected to a triangular load is considered. Results for static model, in which the mechanical properties are constant and dynamic model which has strain rate dependent mechanical properties are compared for various stacking sequences and load magnitudes. The results show that the deflections are overestimated by static model and the difference between static and dynamic models results increases with the magnitude of load. Furthermore, the variation trend of maximum displacement with stacking sequence is the same for both material models.
The Dynamic Analysis of the Notation Reducer With Swinging Bevel Gears
Authors: Liu Huran
Published: May 2012

A new kind of notation reducer suitable for the low velocity, large torque, high efficiency and mutable velocity output have been researched and developed in this paper. There are a series of creations and in advantage, such as, the oil flow distribution, the principle of reducer, the output mechanics and the total structure. It features in the simple in construction, small of size, large ratio of reducer, high f ratio of torque-power, and low in energy consumption. It is suitable for all the occasions with hydraulic supply and all the fields when low velocity, large torque, high efficiency and mutable velocity output ware needed. Such as the construction mechanics, ship mechanics, heavy machine tool, heavy capstan and so on. The frequency of the hydraulic system is about 1000–2000/min, the reduced ratio of the planetary drive of swinging bevel gear is about 20–100, with 150 the maximum. This paper introduced the fundamental principle of the transmission of this mechanics, designed the basic structure of this mechanics, and analyzed the movement and forces.
Stability of Liquid Films
Authors: Narendranath Aneet D. , Kimball Jeramy , Hermanson James C. , Kolkka Robert W. , Allen Jeffrey S.
Published: May 2012

Macroscopic thin liquid films are entities that are important in biophysics, physics, and engineering, as well as in natural settings. They can be composed of common liquids such as water or oil, rheologically complex materials such as polymers solutions or melts, or complex mixtures of phases or components. When the films are subjected to the action of various mechanical, thermal, or structural factors, they display interesting dynamic phenomena such as wave propagation, wave steepening, and development of chaotic responses. Such films can display rupture phenomena creating holes, spreading of fronts, and the development of fingers. The present work examines, through the solution of a onesided evolution equation as an initial value problem with periodic boundary conditions, the various mechanisms that affect the stability of liquid films. The numerical program employed to solve the non-linear evolution equation is validated by comparing the results produced with previously published data. The wavenumber associated with various destabilizing mechanisms is extracted. The effect of pinned boundary conditions versus periodic boundary conditions will be discussed.
Analytical Solution of Chamber Effective Length in the Axial Engine
Authors: Dehghani S. R. , Mozafari A. A. , Saidi M. H. , Ghafourian A.
Published: May 2012

In this research chamber effective length, which is the minimum chamber length required for complete combustion, for a dilute monopropellant spray, constant area, one dimensional and fixed volume engine is analytically predicted. A new evaporation rate in the form of dk+1 relation, instead of d2 law, is introduced. In case of controlling the vaporization by radiative heat transfer, k is equal to zero, and when molecular processes control the vaporization, k will be equal to unity and in some cases the vaporization data need the value of k greater than one to fit properly to related equation. Development of this approach can be used in design of combustion chambers with optimum length and with using vaporization rate of R = R0〈r〉0k/〈r〉k. Spray equation and distribution function in one-dimensional coordinate in direction of chamber axis is used as governing equations. Multiplying velocity and displacement variables by the simplified spray equation and some manipulation lead to a final form of integral equation. Definition of β1β3 as criteria will simplify the complex integral equation to a solvable relation. Results provide dimensionless velocity of droplets (from initial state to completely vaporization) and the chamber effective length for various values of k. The results obtained by employing dk+1 relation show that increasing k increases in the droplet vaporization rate as well as the oxidizer velocity and decreases in the chamber effective length.
Optimum Layout of Passive Constrained Layer Damping Treatment Using Genetic Algorithms
Authors: Hou S. W. , Jiao Y. H. , Chen Z. B.
Published: May 2012

The passive constrained layer damping (CLD) treatments have been used widely for vibration suppression of various flexible structures. Fully covered CLD treatment is extensively used to depress the vibration over a wide frequency range in engineering applications. In most of these treatments it is required that the CLD treatment should not significantly increase the weight or volume. This paper focuses on damping optimization of fully coating beam with a constrained viscoelastic layer. The governing equation of motion of a CLD covered beam is derived using an energy approach and Lagrange’s method. The assumed modes method is employed in solving the equation to obtain the modal loss factors which are used as the objective of optimal layout. A genetic algorithm with large-scale mutation method is employed to search for the optima of the thicknesses of both the constraining layer (CL) and the viscoelastic layer (VL) and the shear modulus of the viscoelastic material (VEM) with the restriction of added volume of the total CLD treatment. Numerical results show that the optima of three design variables, the thicknesses of the CL and the VL and the shear modulus of its viscoelastic material, are highly relevant to each other. The softer or thinner constraining layer requires a softer viscoelastic material for an optimal damping treatment, and high value of the elastic modulus of the base beam matches high shear modulus of the viscoelastic material. The variation of the CL thickness decreases slowly and that of the VL thickness increases with the increase of the thickness of the CLD treatment. Stiffer constraining layer assure greater modal loss factors.
Identification of Underwater Vehicle Hydrodynamic Coefficients Using Model Tests
Authors: Sadeghzadeh B. , Mehdigholi H.
Published: May 2012

Predicting the hydrodynamic coefficients of an autonomous underwater vehicle (AUV) is important during vehicle design. SUT-2 is an AUV, being developed by the Marine Engineering Research Center of Sharif University of Technology in Iran (MERC). Model tests are done in the marine engineering laboratory towing tank. In this research, hydrodynamic coefficients are calculated using model test results of an autonomous underwater vehicle. Hydrodynamic forces are also analyzed. These coefficients are used for dynamic modeling and autonomous controller design.
Reliability Assessment of 3D Chip Stacking Package Using Metal Bonding and Through Silicon Via Technologies
Authors: Syu Shih-Yi , Hung Tuan-Yu , Huang Chao-Jen , Wang Han-Jung , Lee Hsin-Li , Chiang Kuo-Ning
Published: May 2012

In this study, the thermo-mechanical finite element (FE) analysis of the 3D chip stacking packaging is accomplished by employing the commercial software, ANSYS®. After manufacturing process, the thickness of the deposited material becomes variable. For the most part, this is due to the uncertainty of the manufacture process. In analyzing the effect of thickness difference, the process modeling technique is adopted. The technique can be demonstrated by comparing simulation results and the designed experiment for established chip displacement measurements. The out-of-plane displacement of the fabricated chip is measured by the Twyman-Green (T/G) interferometer. According to the results simulated by the validated process modeling technique, the effect of the thickness difference of the ABF layer is insignificant. In thermo-mechanical FE analysis, the thermal expansion of ABF material can induce stress concentration at the copper via. Moreover, thermal expansion of the ABF material and copper via can also affect the reliability of the silicon chip. Based on the design concept, the effect of the copper via diameter is analyzed. Based on the results, the stress concentration phenomenon at the copper via improves as the diameter increases. However, a larger thermal expansion of the copper via can damage the chip structure because of the larger diameter.
Numerical Predictions of the Performance in Flight of an Air-Breathing Hypersonic Vehicle: HyShot II
Authors: Iaccarino Gianluca , Pec´nik Rene , Terrapon Vincent , Doostan Alireza
Published: May 2012

The uncertainties inherent to the operating conditions of the Hyshot II scramjet flight test are assessed. In particular, the variability of the pressure prediction in the combustor due to uncertain free stream conditions is investigated using a probabilistic methodology based on stochastic collocation. The uncertainties in Mach number, angle of attack and flight altitude are inferred from pressure measurements in the unfueled combustor using a Bayesian inversion approach. The forward computation relies on a reduced order model that represents the combustion processes in the scramjet combustor. A ground based experimental data set obtained from 1-to-1 model of the HyShot II vehicle with well defined operating conditions is used to validate the non-reacting solver and to calibrate the heat release model for the reacting combustor. The model prediction agrees well with the experimentally aquired flight data. On the other hand, our estimated flight free stream conditions differ from previously published results.
Time-Limited Ageing Analyses for Justification of Long-Term Operation of Paks NPP
Authors: Katona Tama´s Ja´nos , Ra´tkai Sa´ndor , Ja´nosine´ Bi´ro´ A´gnes , Go˝si Pe´ter
Published: May 2012

In this paper a comprehensive set of the time-limited ageing analyses for justification of long-term operation of WWER-440/213 type units will be presented. The scope covers mainly fatigue analyses of Safety Class 1 and 2 structures and components, reactor pressure vessel pressurized thermal shock analyses, etc. like in usual practice in case of PWRs. However some specific analyses are required for comprehensive justification of long-term operation, e.g. high cycle fatigue analysis of flow-induced vibration of internal structures of the reactor pressure vessel and internal structures of the steam generators, thermal ageing analysis of Safety Class 1 and 2 components, analysis for material property change of heavy concrete structures of reactor shielding, crack propagation analysis of detected defects, thermal stratification analysis, fatigue analysis of the containment for increased pressure level during integral leak-tightness test. The necessity of the specific analyses is discussed. Arguments are based on the WWER operation experience and engineering considerations. Specific requirements and methodology for routine and specific time-limited ageing analyses and the most important results with explanation of possible consequences will also be presented.
Time-Frequency Characterization of a Cracked Rotor Sliding Bearing System With Rotor-Stator-Rub
Authors: Alugongo Alfayo A.
Published: May 2012

Constitutive dynamics of a cracked rotor supported on sliding bearings are modeled and analyzed by Wavelet Transform. The effect of the ensuing non-linear disturbances, namely, oil film forces, rotor stator rub forces, and a switching crack on the rotor shaft is numerically simulated. Subsequently, the system response is evaluated under various scenarios and the results reported. A sensitivity analysis on various system parameters is performed and discussed to emphasize the modeling. The current technique as a tool for condition monitoring of rotors has been demonstrated by analysis in this paper.
On the Modeling of Gas-Solid Fluidization: Which Physics Are Most Important to Capture?
Authors: Battaglia Francine , England Jonas A. , Kanholy Santhip , Deza Mirka
Published: May 2012

Recent studies to predict biomass fluidization hydrodynamics motivated a new study to reassess how to model gas-solid characteristics that capture the same physics as that measured in experiments. An Eulerian-Eulerian multifluid model was used to simulate and analyze gas-solid hydrodynamic behavior of the fluidized beds. The relations for the pressure drop measured at fluidization were used to correct for the bed mass by either adjusting the initial solids packing fraction or initial bed height, two parameters that must be specified in a CFD model. Simulations using sand as the bed medium were compared with experiments and it was found that adjusting the bulk density, or in other words, the initial solids volume packing, correctly predicted the pressure drop measured experimentally, but significantly under-predicted the minimum fluidization velocity. By adjusting the initial bed height to correct for the mass, both the pressure drop and minimum fluidization velocity were successfully predicted. Ground walnut shell and ground corncob were used as biomass media and simulations were performed for two reactor bed diameters by simply adjusting the initial bed height to match the measured pressure drop. All of the simulations correctly predicted the pressure drop curves of the experimental data. Further examination of the simulations and experimental data for walnut shell confirmed that adjusting the bed height was the best approach to model fluidization without artificially altering the physics and retaining the known characteristics of the bed material.
Studying the Design of PWM Controllers for Air Motors With an Indirect Approach of Speed Measurement
Authors: Zakeri Vahid , Arzanpour Siamak
Published: May 2012

Efficiency of the air motors is a function of different variables, including the head and velocity of the fluid at the inlet and outlet of the air motor, and the load on its shaft. Among these variables, angular velocity control of air motors is a challengeable area for engineering. Although servo valves seem to be promising solutions for this application, however, they are slow and expensive. As a result, they cannot properly manage the fluctuations and discontinuities of the flow as well as the disturbances in the load for the optimum efficiency. This paper has studied designing of a PWM controller for air motors by investigating different pulses with different frequencies and duty cycles. In addition, considering practical point of view, speed-measurement in rotary systems can be challengeable and sometimes impossible. These changes such as detachment and reattachment of the shaft of the system, or installing the encoder around the shaft are sometimes impossible practically Thus, this paper has also presented an indirect method of speed-measurement by using vibration signature of air motors measured by accelerometers and microphones. The experimental results indicate the capability and suitability of this indirect measurement.
The Comparison Between the Theoretical Section Line and the Actual Section Line of the Vane Wheel by the 5-Axis NC Machining
Authors: Ran Liuhu , Yi Lou , Liu Quanhong
Published: May 2012

An accurate method to calculate the section line of the complicated surface after numerical controlled machining is presented in this paper. The method to calculate the tooth surface of the conjugate gearing is applied into the field of sculptured surface machining. It is the most precise method to determine the remaining scopes on the surface. The calculated remaining scopes are exact the same as that in practical cutting. The concept of contact is applied into the machining of the complex surface. If the contact line along the straight line of cutter, the contact line should along the asymptotic direction of the surface being machined. For the undeveloped ruled surface, the directions of the normal vectors are different, while the directions of the normal vectors on the straight line of cylinder are the same, so that there may be some over cutting on the surface. With the theory of this paper, the best cutter postural can be determined when the contact line not along the straight line of the cutter. And further more, with the concept of third order contact, both the best cutter postural and contact direction can be determined at same time.
Master-Slave Control Technology Research for Abdominal Minimally Invasive Surgery Robot
Authors: Fu Yili , Li Han , Xie Qi
Published: May 2012

According to characteristics of abdominal minimally invasive robotic surgical tasks, based on performant industrial computer platform, an extended multifunctional hardware communicates with PCI-bus is designed, a master-slave control system is studied. In order to solve the problem of low responsivity caused by traditional inverse kinematics transformation method, a algorithm based on equivalent differential transformation suitable for real-time master-slave surgical robot control is put forward, and the accumulated error of the algorithm is eliminated by feedback mechanism. A fast trajectory planning method efficient in real-time master-slave surgical robot control is put forward to replace traditional trajectory prediction and off-line calculation. Finally, in order to avoid the impact on the accuracy of the system coursed by hand-trembling of operators, a digital filter is designed to help filtering the master manipulator signal.
Prevention of Surface Crack Formations on Polymeric Coatings Using Carbon Nanotubes
Authors: Asmatulu R. , Mahmud G. A.
Published: May 2012

Polymeric coatings are frequently utilized for the protection of materials surface against UV light and other environmental factors (e.g., oxygen, pollutants and moistures) by many industries. However, the organic films have yet to be perfected and failures due to the degradation caused by the environmental factors are potential hazards. These hazards can cost the US economy billions of dollars and cause serious accidents. In order to minimize UV and other environmental factors on the polymeric coatings, new studies are focused on functional coating systems. In the present study, we have developed a nanocomposite coatings to reduce the crack formations and increase the life-time of the coatings. Different weight percentages (0%, 0.25%, 0.5%, 1% and 2%) of multi-wall carbon nanotubes (MWCNTs) were indvidually dispersed in the coating maetrials, and then sprayed on the surfaces of aircraft Al alloys. UV light and salt chamber tests were applied to the prepared coating samples. Optical microscopy and atomic force microscopy (AFM) studies showed that the micro and nanocrack formations on coatings were significanly lowered at higher MWCNT loadings (e.g., 2%). As a results, it is concluded that CNTs played a vital role in protecting of polymeric coatings against UV degradation and corrosion.
Enhancing the Superhydrophobic Behavior of Electrospun Fibers via Graphene Addition and Heat Treatment
Authors: Ceylan M. , Asmatulu R.
Published: May 2012

Polyvinyl chloride (PVC) fibers incorporated with graphene nanoflakes were produced using electrospinning technique, and then superhydrohobicity of the electrospun nanofibers were investigated as a function of inclusion and temperature. In the absence of graphene, water contact angle of the fibers is below 140°; however, the water contact angle values of 0.5, 1, 2 and 4% graphene in fibers become 142, 152, 165 and 166°, respectively. Using a heat treatment, the contact angle values of samples also increase up to glass transition temperature of PVC. This indicates that graphene inclusions in the polymeric fibers and temperature drastically change the surface morphology and chemistry, which results in higher contact angles. The reason behind this phenomena may be the formation of smaller nanosized graphene bumps on the fiber surface that make the contact area between the droplet and the fiber extremely small. As a result, this process minimizes attractive forces between the water molecules and surface atoms of the rough nanocomposite fibers to bead up and rolls off.
Electrical Properties of Recycled Plastic Nanocomposites Produced by Injection Molding
Authors: Reddy R. J. , Asmatulu R. , Khan W. S.
Published: May 2012

Plastic recycling is a recovery process of waste plastics to make new products into different forms. Plastics are usually sorted based on their resin identification codes before the recycling and melting processes. Although the recycling rate of plastics is significantly high, properties and economical value of the recycled plastics are fairly low, which in turn limits the use of recycled plastics in the market. In the present study, high density polyethylene (HDPE) in the form of pellets was dissolved in toluene, and then nanoscale graphene inclusions at different loadings (e.g., 0%, 0.25%, 0.5%, 1%, 2% and 4%) were added into the polymeric solutions. The remaining solvent was removed from the nanocomposite before the injection molding process. The injection molding process was conducted on the chopped recycled plastics associated with graphene loadings. The dielectric and electric properties of plastic nanocomposites were studied in detail. The test results showed that the dielectric properties were slightly improved by the addition of inclusions, which may be due to the non-polar nature of HDPE and/or residues in the recycled plastics. However, electrical conductivities of nanocomposites were significantly increased because of the improved electrical conduction, polarization and electron mobility at room temperature.
In Vivo Studies of the Drug Carrying Magnetic Nanocomposite Spheres via Fluorescent Molecules
Authors: Misak H. E. , Asmatulu R. , Gopu J. S. , Zheng S. , Wooley P. , Yang S.-Y.
Published: May 2012

Nanospheres utilized in targeted drug delivery systems have seen much attention, however it is difficult to detect the nanospheres in an in-vivo test due to their nanoscale in size. This is a crucial step in targeted drug delivery to show the nanosphere being concentrated at the spot of interest. Nanospheres developed by oil in oil (o/o) emulsion technique have the advantage of encapsulating molecules, such as 1,6-Diphenyl-1,3,5-hexatriene (DPH), without damages and chemical alterations. In current study, DPH was encapsulated into a nanosphere as a fluorescing tracer to visualize the nanospheres trafficking in a mouse model of squamous cell carcinoma (SCC). The SCC tumors were established on nude mice. 0.5 ml of a 0.3 mg/ml solution of fluorcescent nanospheres were subcutaneously injected around the tumor. The injections of the drug carrier system were repeated at 2-day intervals till the sacrifice of the tumor-bearing animals on day 10. The tumors were retrieved for frozen and paraffin-embedded histological preparation. Fluorsescent microscopy was used to image the frozen sections, and compared with H&E stained sections. The fluorescence nanoparticles were easily identifiable under fluorescent microscopy, while typical histology images were unable to detect the nanospheres. The data suggest that fluorescent nanoparticles can be used to identify the location or localization of the nanospheres in an in-vivo environment in a simple and straightforward method that aids in characterization of targeted drug delivery.
Fabrication of High Aspect Ratio Microcoils Using X-Ray Lithography
Authors: Noda Daiji , Setomoto Masaru , Hattori Tadashi
Published: May 2012

Recently, the demand of micro-fabrications such as micro-sensors, microcoils, micro-actuators etc is increasing. Actuators account for a large percentage and volume and weight of a product compared with other parts. Therefore, the progress in downsizing of actuators was required. In order to resolve these problems, the key technology to realizing micro-devices is micro-fabrication process. Particularly, it is essential to the technologies for processing high aspect ratio structures in the production of micro-parts. We have proposed a three-dimensional fabrication process using X-ray lithography technique, and fabricated spiral microcoils having coil lines of narrow pitch and high aspect ratio structures. We have fabricated spiral microcoils at a pitch of 60 μm, and aspect ratio of about 5 using X-ray lithography and narrow metallization techniques on acrylic pipe surface. In addition, we also estimated the suction force of electromagnetic actuators using these microcoils. Measurement results were relatively in good agreement with theoretical values using high aspect ratio microcoils. It is very expected that the high performance microcoils could be manufactured in spite of miniature size.
Fabrication of High Performance Light Guide Plate and New Design for High Luminance
Authors: Fujimoto Takaya , Yamashita Kenji , Nishida Satoshi , Noda Daiji , Hattori Tadashi
Published: May 2012

Recently, LED (Light Emitting Diode) is paid to attention as a new source of light. However, it doesn’t turn to shine on a wide area efficiently because LED is a point light. Then, the method of the light guide plate technology used for the liquid crystal display etc, and use as the LED lighting is examined. A minute reflection dots exists bottom of the light guide plate, system is such that light comes out from the surface because the light that hits the dots break a total reflection condition. In our laboratory, the function of the diffusion seat and the condensing prism seat that is complete parts of the lighting panel was involved by optimizing shape and the arrangement of the dots, and it works on the research of the light guide plate where uniform luminescence is enabled. In the process of study, it has been understood that luminance increases by increasing the number of dots, too. Therefore, an accumulating method of piling up two or more light guide plates was proposed as a method of achieving high luminance for highly effective lighting usage, and the device was analyzed with an optical simulator. As a result of optimization, the average luminance has improved by 15%. We are starting to fabricate this high luminance light guide plate by accumulating method. If this piled light guide plate is completed and luminance is improved in accordance with the simulation, it will be possible to convert it to a higher luminance light guide plate.
Investigation of Residual Thermal Stresses in Fiber-Reinforced Composites Incorporating Inhomogeneous Interphase Region
Authors: Shokrieh M. M. , Ghanei Mohammadi A. R.
Published: May 2012

In this paper, a new finite element model has been introduced with the aim of efficient investigation of residual thermal stresses in fiber-reinforced composites, in which the inhomogeneous interphase is considered. For the inhomogeneous interphase modeling, four different kinds of material properties variation of the interphase (power, reciprocal, cubic and exponential variations) with the radial coordinate have been used. A mono fiber circular unit cell is considered using a finite element (FE) method. Extending the mono fiber model, FE models with different arrays of fibers have been created to investigate the effects of neighboring fibers on the results. In order to assure the convergence of results, a convergence analysis has been carried out for each of the models. To verify the finite element model, the FE results are compared with theoretical results available in the literature. In this paper, three different types of RVE configurations, circular, square and hexagonal are modeled and the effects of each type of fiber packing are studied. Performing an extensive study, the appropriate boundary conditions for RVEs are presented. The boundary conditions presented in this research are proved to be able to model the overall behavior efficiently.
Optimal Design of Multi-Utility Complex for a Low Carbon City in China Integrating Renewable Energy
Authors: Pan Yiqun , Li Yuming , Shi Jie , Wang Chunxiang , Jeong Kwan Seok , Kim Jaemin , Lee Ji-young , Johnstone Cameron , Hong Jun , Park Ji Young , Park Gyoung Min
Published: May 2012

There are many new city and district development projects ongoing in China, which are aimed at developing and building the low carbon emission cities of the future. The Energy Utilities sector is also facing new challenges from policy and regulations aimed at improving energy efficiency, adopting clean energy and mitigating environmental impact. As such, energy supply systems are becoming increasingly complex due to the installation and operation of multiple renewable energy systems. A Multi Utility Complex (MUC) has been proposed as a new and more effective way of constructing urban utility systems, in which facilities for utility services (e.g. energy supplies, water/sewage treatment and waste management plants) are physically installed at one site and managed by an integrated operating centre. When designing a MUC to be ‘cleaner’, more efficient and economical, determining an appropriate capacity of each component constituting the MUC is an essential and not trivial task due to the complexity of resource /energy flows and constraints associated with energy policy and regulations. To address this, an optimization design methodology has been adopted on the basis of a population-base optimization algorithm in support of cost-effective investment. The methodology is implemented in a software tool, ‘Plant Optimizer’, equipped with an urban utility demand profile modeller, the MUC package with different installation scenarios, analysis modules and reporting facility. This paper describes the optimizing methodology and functions of the software tool, and presents a case study to demonstrate the applicability.
A CFD Study and Geometrical Improvement on Heavy Duty Diesel Engine for Ultra-Low Emissions
Authors: Koten H. , Yilmaz M. , Gul M. Z.
Published: May 2012

The goal of this study is to find out effects of the injection parameters on the combustion process for a single cylinder of a nine-liter six cylinder diesel engine. Partially premixed compression ignition (PPCI) cases are compared for improvements on the combustion chamber design of the engine to achieve near zero particulate matter (PM) and NOx emissions for homogenous charge compression ignition (HCCI) engine. Therefore combustion simulations of the engine have been performed to find out flow development and emission generation in the cylinder. Moreover, the interaction of air motion with high-pressure fuel spray injected directly into the cylinder has also been analyzed. Finally, a comparison has been made considering the performance of the engine for various configurations such as compression ratio, injection timing, cone angle and bowl geometry. The results are widely in agreement qualitatively with the previous similar experimental and computational studies in the literature.
Spot Weld Layout Optimization With Manufacturing Constraints for Vehicle Structural Performance
Authors: Wu Xueyuan , Xia Yong , Zhou Qing , Cai Wayne , Tilove Robert B.
Published: May 2012

Spot weld layout on thin walled vehicle structures is an influencing factor to the structural performance such as NVH, durability and crashworthiness. The weld layout is also subject to manufacturing constraints such as minimum weld pitch, thickness and curvature of flanges, and accessibility of weld gun. Using an S-shaped thin walled tube as an example, this paper presents a study of spot weld layout optimization considering both structural performance and manufacturing constraints for reducing design iterations between the performance design and the manufacturing design. First, several complex manufacturing constraints, including minimum spot weld pitch, maximum curvature of flange, etc., are mathematically characterized. Then, with and without typical manufacturing constraints, the weld layout is optimized respectively for crash performance and torsion performance of the structure. The effects of adding manufacturing constraints on the spot weld layout optimization are evaluated. The analysis results reveal that the crash performance responses are generally less sensitive to the spot weld layout while the torsion stiffness is closely related to the spot weld layout. To analyze why the crash performance is less dependent on the weld layout, a detailed study is further conducted to reveal the relation between the weld layout and the crash performance of S-shaped thin walled tube. It shows that the parameters for assessing the structural crash performance have distinct sensitivity to the spot weld layout design. For instance, the peak impact force is generally sensitive to the spot welds placed in the curved segment and the total energy absorption capacity is mainly determined by the curvature design of the tube instead of the spot weld layout design.
Parametric Analysis on a Novel Hybrid System of Solid Oxide Fuel Cell and Micro Gas Turbine
Authors: Zhang Wenshu , Zhang Huisheng , Weng Shilie
Published: May 2012

This paper presents the steady state parametric analysis of the solid oxide fuel cell and micro gas turbine hybrid system based on the IPSEpro software. The characteristic of the novel hybrid system is that both the fuel entering the heat exchanger reformer (HER) and air entering the fuel cell are preheated by mixing with the anode exhaust and cathode exhaust respectively, and thus the normally used heat exchangers can be cut. The heat exchange reformer is introduced for methane reforming. The analysis of the effects of methane reforming degree and the fuel utilization on the hybrid system performance is performed. The efficiency of the hybrid system is up to 67.3% at the design point. The results show the novel hybrid system has great potential for the practical application.
Integrity Management of Offshore Platforms: A Case Study of a Multinational Company in the Coast of West Africa
Authors: Ajayi O. O.
Published: May 2012

Integrity Management of pipeline structures and offshore platforms is of great concern in the oil industry to prevent failure and damage which can result in ecological and environmental pollution. This paper presents the experience of a multinational oil company in the coast of West Africa. It will focus on how integrity management is used as a proactive measure to prevent corrosion and damage to offshore platforms. The paper will focus on planning, implementation and management of the integrity management strategy in the company. The case study described in this paper will focus on the best practices and lessons learnt from other companies operating in the region.
An Optical Encoder Using Micromachined Two Gratings With Phase Difference
Authors: Shin Dongwon , Kim Byungki
Published: May 2012

This paper presents a new type of optical encoder which generates a quadrature signal with resolution of 1/8 wavelength of the laser source. The sensor is composed of two diffraction gratings with the period of 4μm and 6μm, which has step difference 86nm, so that the signals generated from two diffraction gratings have about 90° phase difference. The simulation and experiment results for displacement measurement show the validity of the proposed optical encoder.
Heat Transfer in a Stretching Sheet Problem in Electrically Conducting Newtonian Liquids With Temperature-Dependent Viscosity
Authors: Sekhar G. N. , Chethan A. S.
Published: May 2012

The classical Crane problem of the stretching sheet is extended to include temperature sensitivity of weakly electrically conducting Newtonian liquids. The thermo-rheological equation of state subscribed to in the problem involves an inverse relationship between dynamic viscosity and temperature. The problem is solved using the shooting technique with assistance from a series solution procedure. The Classical explicit Runge-Kutta fourth order method is used to solve the initial value problem by the shooting technique. The results show that the effect of variable viscosity is to hasten the boundary layer flow leading to an increase in heat transfer. The problem has applications in extrusion processes, thin films and such other applications.
Determining the Tool Life of a Cemented Carbide Drill Using Optimized Process, Delivery System, and Drill Design Parameters in Deep Hole Drilling Using Environment Friendly Machining Method
Authors: Hussain Muhammad I. , Filipovic A. , Dasch J. , Simon D.
Published: May 2012

Near dry machining or Minimum Quantity Lubrication (MQL) methodology appears to be a valid solution to meet environmental challenges of metal removal processes. However, in order to implement environmentally friendly machining into high production manufacturing environments, it is imperative to invent a robust solution for a wide variety of machined features. In previous work by the authors, capabilities of the MQL process, calibrated for machining extremely deep holes with length to diameter (L/D) ratio of up to 15, were proven. An optimal machining solution was developed using the Box and Behnken experimental design approach, and it was demonstrated that cemented carbide drills with proper cutting geometry and MQL settings can be used for deep hole drilling of aluminum. This work, focused on developing a production ready application, proved that MQL technology is also robust enough to achieve adequate tool life for high volume manufacturing requirements. It actually exhibited that such approach may even exceed tool life requirements currently enforced for conventional processes using gun drills or G-drills. In addition, machining time was significantly reduced with this innovative technology achieving productivity approximately 7 times higher than in traditional drilling operations. Considering these achievements, MQL has been demonstrated to be the drilling technology of future that will help reducing capital investments into production machinery and minimize landfill discharges of high production manufacturing facilities.
Investigation of Chaotic Dynamics in MST Based Precision Sensors
Authors: Tabe Arjmand M. , Spiewak Swavik
Published: May 2012

This paper is concerned with the accuracy and signal detection limits in ultra precision, Microsystems Technologies based inertial sensors. It focuses on conditions that lead to chaotic dynamics, detection of such dynamics. Development of the needed constitutive-empirical, scale-able models is presented and illustrated by example of axially preloaded microflexures. To eliminate uncertainties caused by the accumulation of numerical errors in commonly used engineering software we employ arbitrary precision computations. We detect chaotic dynamics in the investigated systems by means of Poincare map technique to show the evolution of phase space from deterministic to chaotic behavior.1
Design, Modeling, and Optimization for Highly Efficient Ionic Wind-Based Cooling Microfabricated Devices
Authors: Ongkodjojo Andojo , Abramson Alexis R. , Tien Norman C.
Published: May 2012

The purpose of this work is to re-design, model and optimize a single microfabricated ionic wind pump device [1]. The device could then be employed in a three-dimensional array for use in larger-scale microchip cooling and enhanced thermal spreading applications. The innovative microfabricated air-cooling technology employs an electrohydrodynamic corona discharge (i.e. ionic wind pump) for efficient heat removal from electronic components. Our single ionic wind pump element consists of two parallel collecting electrodes between which a single emitting tip is positioned. The collector electrodes are patterned with a grid structure, which enhances the overall heat transfer coefficient and facilitates a batch and IC compatible process. Various design configurations are explored and modeled computationally to investigate their influence on the cooling phenomenon. In particular, COMSOL Multiphysics™ is employed to computationally explore the effects of collector-emitter configuration on the electrohydrodynamic phenomenon, the flow field and resulting cooling effects. Using both computational and experimental results, we estimate that a two-dimensional array of microfabricated ionic wind pumps covering approximately 2″ square should be able to dissipate greater than 2 W of heat, using about 1/5 the power input as a conventional fan.
Simulation of NOx Reduction in an Ammonia-SCR System With an Fe-Zeolite Catalyst and Calibration of Related Parameters
Authors: Sharifian L. , Wright Y. M. , Boulouchos K. , Elsener M. , Kro¨cher O.
Published: May 2012

NOx reduction in a single representative channel of an SCR converter is modeled accounting for convective mass transfer along the channel, diffusive mass transfer and chemical reactions within the catalytic layer, coupled via mass transfer boundary condition at the wall. The proposed 1D+1D code for the channel has different parameters involving rate expression constants for the surface chemistry and properties of the catalytic and washcoated layer. A comprehensive set of experimental data on the Fe-Zeolite washcoated monolith was available for different feed concentrations, temperatures and flow rates. A genetic algorithm was used as an optimization technique to calibrate the model parameters by minimizing the error between simulation results and transient responses of the real system. Dynamic tests showing the response of the system during fast transients were subsequently used to assess the predictive quality of the model with the calibrated parameters. In particular, different rate expressions for the surface reactions were compared to find the best fit for the tested catalyst, providing insight with respect to the importance of the different reaction pathways and the chemico-physical properties of the system. Based on the findings, an optimization strategy could be proposed both in terms of sequence as well as minimum required experimental tests for each sub-system according to the parameters which can be determined separately.