bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Equipment for Manufacturing Helically-Coiled Tubes and its Automatic Control System
Authors: Chen Chang-Nian , Han Ji-Tian , Shao Li , Jen Tien-Chien , Yen Yi-Hsin
Published: May 2012

A simple but accurate method for manufacturing helically-coiled tubes was proposed, and the manufacturing equipment and its automatic control system were designed. The main geometric parameters of helically-coiled tubes are determined exactly based on the theorem “three given points determine a circle” and the definition of the helix angle of helically-coiled tubes. The finished equipment primarily consists of the mechanical noumenon and the automatic control system. In this design, three die wheels A, B and C made of wearable steel are used to adjust the positions of the raw materials in order to determine the product geometric parameters expected in advance. Three servo motors working with precision linear sliding rheostat and PID closed-loop control functions drive the three wheels mentioned above in different directions. The parameter e determining the base circle diameter of coil diameter is obtained by adjusting the position of wheel C up and down, and the parameter e’ determining the helix angle is obtained by adjusting the relative distance between wheel B and wheel A in the helical axis direction. The whole manufacture process is automatically controlled by a piece of software compiled by Visual Basic, including the processes of baiting and cutting, installing wheels and calibration, motor controlling, bending tubes, and product inspection etc. The design parameters for manufacturing helically-coiled tubes using SUS304 stainless steel or other similar materials are tube diameters of 6–50 mm, coil diameters of 100–700 mm and helical pitches of 10–50 mm. A total of fourteen finished products were selected as random samples for inspection. The result showed that the average working velocity was about 0.6 m/min; the root mean square errors (RMSE) of coil diameter and helical pitch of finished products were 3.85 mm and 0.97 mm, respectively; and the maximum roundness error of tubes was only 0.09 mm.
Design and Performance of Two-Phase Flow Heat Transfer Experiment Platform Using R134a as Working Fluid
Authors: Chen Chang-Nian , Han Ji-Tian , Shao Li , Jen Tien-Chien , Yen Yi-Hsin
Published: May 2012

A two-phase flow heat transfer experiment platform using alternative refrigerant R134a as working fluid was designed and built to investigate the characteristics of two-phase flow heat transfer. It was primarily made up of circle power, heating/cooling sources, parallel test sections, accumulator and data acquisition system. The working loop was designed for performance pressure of 1.6 MPa and temperature of 200°C, preheated section power of 24 V × 300 A and test section of 60 V × 500 A. The refrigeration chilling unit had a maximum output of 50 kW. The preheated and test section were designed as horizontal helically-coiled tubes, and a visual reservoir made of electric melting-quartz glass was designed to observe flow patterns intuitively. Technology and methods related to fluid and mechanics were discussed in this paper including the aspects of materials and welding, sealing and heat preservation, special machining and accessories installation etc. Pressure testing, heat balance testing, heat transfer characteristics experiments were performed under various conditions to analyze the usability and stability of this platform. Test results showed that the leak ratio was no more than 250 Pa/h at 2.0 MPa and the heat loss of the system wrapped with PEF materials was less than 5%. Under the conditions of pressures of 0.30–0.95 MPa, mass fluxes of 120–620 kg/m2s, inlet qualities of −0.08–0.38 and heated power of 0.45–1.30 kW, R134a two-phase flow boiling heat transfer characteristics were investigated and discussed in detail. This platform can be used for studying the characteristics of two-phase flow pressure drop, boiling heat transfer and fluid-to-fluid modeling technique etc.
Emulation-Based Optimal Control of Chiller Plants
Authors: Huang Zhizhong , Pan Yiqun , Wu Gang
Published: May 2012

Chiller plants of HVAC systems usually operate in part-load conditions during most time of a year. Energy efficiency (i.e. energy input ratio, EIR) of chiller plant components such as chillers, pumps, and cooling towers are the functions of part-load ratio (PLR) and other variables. However, different chiller plant components have different functions of EIR to PLR and don’t reach their respective peaks at the same part-load ratio. Based on this fact, there are possibilities that overall efficiency of a chiller plant can be improved to and maintained at the maximum via optimal control of operating numbers and set-points of various plant components at various part-load ratios. An emulation-based optimal control strategy for chiller plants is introduced in the paper. The main idea of this control strategy is to set up a virtual chiller plant as a mirror of a real system. The virtual system is composed of mathematical models that are obtained through theoretical derivation, numerical calculation or off-line test. These models can emulate energy performances of the physical components in the real system. An optimization algorithm is first run on the virtual system to search for an optimal combination of the operating number and set-points of various components to achieve the highest overall efficiency of a chiller plant. An objective function of the optimization algorithm is the overall efficiency of a chiller plant, having real-time cooling load and meteorological data as inputs, and energy and mass balance and component capacities and restrictions as constraint conditions. Once an optimal combination is identified, it will be used to control the real system operation. A mockup system has been installed and operated in a 50,000 m2 office building in Shanghai, China in order to test and verify the optimal control strategy. Preliminary testing results show that the annual overall energy efficiency of the chiller plant (with constant speed centrifugal chillers) is from 0.7 kW/Ton to 0.75 kW/Ton, about 25% less than that of the same plant controlled by normal strategy.
Experimental Analysis on the Tightening Torque - Preloading Force Relationship in Threaded Fasteners
Authors: Croccolo D. , De Agostinis M. , Vincenzi N.
Published: May 2012

The aim of this study is to provide an experimental methodology useful to determine the friction coefficients in bolted joints and, therefore, to relate precisely the tightening torque to the preloading force. The components under investigation are some clamped joints made of aluminium alloy and used in front motorbike suspensions to connect the steering plate (fork) to the legs and the legs to the wheel pin. The aluminium alloy is realised by a casting or a forging process afterwards anodized or spry-painted in surface. Some specific specimens have been appropriately designed and realised with the same process of the actual components. The bolt torque is given by a torque wrench whereas the preloading force has been evaluated by means of a strain gauge. Thread and underhead friction coefficients have been studied separately, by applying an axial bearing located between the bolt head and the flange of the specimen. The overall friction coefficient and the torque coefficient (nut factor) have been calculated. Experimental tests have been carried out by applying the Design of Experiment (DOE) method in order to obtain an accurate mathematical model that involves the significant friction variables and their interactions. The results of this preliminary study have been, then, applied to those connections used in front motorbike suspensions to lock the steering plates with the legs and the legs with the wheel pin, by means of one or two bolts. The preloading force, produced during the tightening process, should be evaluated accurately, since it must lock safely the shaft, without overcoming the yielding point of the hub. Firstly, the applied tightening torque has been precisely related to the imposed preloading force by means of the friction coefficients definition. The tensile state of clamps, have been evaluated both via FEM and by leveraging some design formulae proposed by the Authors as functions of the preloading force and of the clamp geometry. Finally the results have been compared to those given by some strain gauges applied on the tested clamps: the discrepancies between numerical analyses, design formulae and experimental results remains under a threshold of 10%.
Resonance Behavior of Magnetostrictive Sensor in Biological Agent Detection
Authors: Ramasamy Madhumidha , Prorok Barton C.
Published: May 2012

The growing threat of biowarfare agents and bioterrorism has led to the development of specific field tools that perform rapid analysis and identification of encountered suspect materials. One such technology, recently developed is a microscale acoustic sensor that uses experimental modal analysis. Ferromagnetic materials with the property to change their physical dimensions in response to changing its magnetization can be built into such sensors and actuators. One such sensor is fashioned from Metglas 2826mb, a Magnetostrictive strip actuated in their longitudinal vibration mode when subjected to external magnetic field. Due to mass addition, these magnetostrictive strips are driven to resonance with a modulated magnetic field resulting in frequency shifts. In vibration mechanics the frequency shift for a certain amount of mass will have a tolerance limit based on their distribution and discrete position over the sensor platform. Moreover lateral positioning of same amount of mass does not influence the resonant frequency shift of the sensor. In this regard, this work concentrates on developing a model correlating experimental and numerical simulations to determine the mass of E.coli O157:H7 cells attached to the sensor platform.
Thermo-Fluiddynamic Numerical Simulation and Entropy Generation Maps of an Ultra-Micro-Turbogas Compressor Wheel
Authors: Pierandrei Giovanni , Sciubba Enrico
Published: May 2012

The present study was designed to gain deeper insight of the thermofluiddynamic fields in a compressor wheel. The compressor is part of an ultra-micro-turbogroup developed by the University of Roma 1, co-funded within the frame of a National Research Project, conceived as a portable energy conversion system delivering electricity to a broad range of small devices, for medical, military or emergency use. The expected electrical power output is 400 watts. The turbogroup, fuelled by natural gas, has a single-shaft configuration and is coupled with a reversible electric motor-generator, granting a more compact overall system, encapsulated in a relatively small self-contained assembly. The compressor wheel has an outlet diameter of 38 mm, spins at 175,000 rpm and delivers the fluid to the vaneless diffuser endowed with a static pressure of 155 kPa. The mass flow rate is 0.02 kg/s, and the total inlet temperature is 300 K and the total temperature of the flowing out fluid is about 400 K. The rotor, featuring 6 full- and 6 splitter blades, is coupled with a vaneless diffuser followed by a toroidal volute that collects the almost purely radial fluid at diffuser exit and delivers it to the regenerator. The numerical simulation based upon the k-ε turbulent model has been run within the commercial software Fluent®, on a very fine mesh constructed on a geometry obtained from a commercial turbocharger manufacturer. A critical analysis has been performed on the turbulent structures that evolve within the rotor channel, to better understand the dissipative mechanisms. To this goal, the thermal and viscous entropy generation rate, have been computed on the converged solution of the thermal-fluiddynamic field, and their maps have been inspected to study the development of turbulent structures. The results of this study confirm that an accurate analysis of the local entropy generation rates provides useful hints on how to introduce design improvements and to achieve a higher stage efficiency.
Assessment of Noise Transmission Mechanisms and Approaches to Mitigate Underwater Noise Associated With Installation of Monopile Foundations for Off-Shore Wind Turbines
Authors: Davis Dwight E. , Stokes Ann W. , Warwick David C.
Published: May 2012

This paper reviews our investigation of the underwater noise mitigation technologies applicable to the installation of large monopile foundations. The purpose of this effort is to provide technical background and understanding of the issues surrounding underwater noise generation associated with monopile foundation installation in order to better inform future decisions regarding the need for and effectiveness of proposed mitigation plans and technologies. The paper outlines the fundamental physics basis for the generation and transmission of acoustic energy into the water through three primary paths including airborne-to-water, direct radiation from the wetted structure into the water column, and structure-to-seismic coupling and radiation. Descriptions of the modeling approaches used to assess the significance of each path are presented along with the findings. The models for each path are integrated into a layered-media propagation code that calculates the spreading and distribution from each path, individually and combined, into the water column. The paper then presents the predicted performance for a range of mitigation approaches selected for this study, which focus on the controlling mechanisms of noise transmission. These cases range from highly idealized treatment configurations, intended to bound the performance of any treatment option, to models representing more practical engineering implementations appropriate to the scale of the these structures and the environment. This study was funded by the Department of the Interior Minerals Management Service.
Sustainable Desalination Process Simulation
Authors: Abutayeh Mohammad , Goswami D. Yogi , Stefanakos Elias K.
Published: May 2012

Experimental and theoretical simulations of a novel sustainable desalination process have been carried out. The simulated process consists of pumping seawater through a solar heater before flashing it under vacuum in an elevated chamber. The vacuum is passively created and then maintained by the hydrostatic balance between pressure inside the elevated flash chamber and outdoor atmospheric pressure. The experimental simulations were carried out using a pilot unit built to depict the proposed desalination system. Theoretical simulations were performed using a detailed computer code employing fundamental physical and thermodynamic laws to describe the separation process, complimented by experimentally based correlations to estimate physical properties of the involved species and operational parameters of the proposed system setting it apart from previous empirical desalination models. Experimental and theoretical simulation results matched well with one another, validating the developed model. Feasibility of the proposed system rapidly increased with flash temperature due to increased fresh water production and improved heat recovery. In addition, the proposed desalination system is naturally sustainable by solar radiation and gravity, making it very energy efficient.
Risk-Informed Decision Making for High-Consequence Outcomes
Authors: Smith Curtis , Vedros Kurt
Published: May 2012

The issues faced during the operation of high-consequence facilities or systems require a blended quantitative and qualitative risk-informed approach to decision-making. For example, in the case of the operation of nuclear power plants or manned space missions, a risk-informed metric one might consider is the probability of loss of the plant or failure of the mission, where this probability is balanced by the consequences of the event. However, as we will discuss, one should focus on the observable event itself (e.g., the actual loss or failure) rather than the probability of the event. We will describe the general approach of making probabilistic decisions, including the focus on predictive distributions for outcomes such as a complex system failure.
Fatigue Strength of Ribbon Bonds
Authors: Bresney S. M. , Saigal A.
Published: May 2012

Ribbon or wire bonding is a common manufacturing process used in the microelectronic industry to make interconnections between electronic components. This process is used because it can make up for misalignment and inconsistent spacing between the components due to tolerance stack ups. In addition, since the ribbons are not rigid they will flex and absorb any stresses that develop when the components expand and contract in the field due to temperature changes. This paper investigates the use of a mechanical method to exercise ribbons in this fashion until they failed. Ribbons of a constant profile but different sizes were exercised at different levels of stress to develop a fatigue life model. It is found that ribbons exercised only a small percentage of their overall span survive exponentially longer than the same ribbons exercised at a higher percentage of their overall span. In addition, at short span lengths relative to the thickness, the ribbon becomes less ‘thread like’ and more stiff. The model developed in this study can be used for designing ribbon size and shape based upon expected thermal expansion cycling and necessary life or reliability.
Calculations of Scald Burns: Effects of Water Temperature, Exposure Duration, and Clothing
Authors: Johnson Nessa , Abraham John , Helgeson Zach
Published: May 2012

A numerical model has been constructed to assess the depth of injury incurred when skin is exposed to heated water. The model includes an extended duration which occurs when clothing, saturated with hot water is kept in contact with the skin after the direct exposure has ended. The model takes data from a broad summary of the literature which examines the ranges of reported tissue thicknesses, tissue thermophysical properties, and blood perfusion. Water temperatures ranging from 60–90°C and total exposure durations up to 110 seconds were modeled. As expected, longer durations and elevated temperatures lead to a greater extent of tissue injury. Calculated values of tissue injury were compared with prior injury reports. These reports, taken from the literature, reinforce the present calculations. It is seen that numerical models can accurately predict burn injury as observed in clinical settings, in fact, the calculations of burn injury presented here provide more information for the appropriate treatment of burn injuries compared to visual observation.
Concept Design of Composite Aircraft Wing
Authors: Rao J. S. , Kiran S.
Published: May 2012

This paper is concerned with an optimal concept design of aircraft wing from an airfoil. The airfoil itself is generated from CFD studies but there is no baseline of the wing structure. Topology optimization is recently applied for weight reduction given an operating baseline structure; here it is demonstrated that this optimization can be used to derive the concept of the wing structure directly. The optimized concept design is realized in to CAD and then a composite free-size optimization is performed to determine material distribution and ply drop regions etc. Finally a composite size and shape optimization is done and the ribs thus realized are presented.
Vibrational Effects of the Turbogenerator Bearing Misalignment Defect Represented in the Defect Maps
Authors: Rybczynski Jozef
Published: May 2012

The paper presents results of computer simulation of the bearing misalignment defect in a power turbogenerator and specific methodology applied for presentation of the misalignment effects. Necessary calculations were carried out by means of a set of computer codes composing the system MESWIR, which was developed in the IFFM in Gdansk. For this purpose the turbogenerator final elements numerical model was created and the machine’s response to the simulated defect was calculated. The results are presented in the form of graphs showing the bearing vibration parameters as a function of bearing misalignment. The essence of the presented work is a methodology consisting in presentation of diagnostic relations in the form of “defect maps”. The maps allow to map the machine’s technical state in certain domain of events represented by defects. In this case the “domain of events” is the area of possible bearing dislocations and the “technical state” may be expressed by e.g. vibrations of the machine elements. The result of this work is the complete set of maps, which present distribution of bearing vibration as functions of individual bearing displacements. Within this work various types of bearing misalignment maps were constructed, intended for different applications in the turbogenerator diagnostic system.
Modeling of Two-Phase Micro-Channel Flow for Thermal Management of Electronic Systems
Authors: Zhou Siyi , Sammakia Bahgat G.
Published: May 2012

Traditional thermal solutions are reaching their practical limits on heat removal requirement for processers with high circuit power density over the coming years. The implementation of forced convective boiling in microchannels is a promising alternative, as attainable heat transfer rate is very favorable. In this study, the instabilities of two-phase boiling flow in a single microchannel are computationally explored by utilizing commercial software. Based on previous studies, numerical results get really qualitative agreement. For the steady state, the bubble growth, from isolated bubbles to elongated bubbly flow near the outlet region, can be exactly observed in the current simulation. As for transient analysis, boiling regimes are investigated in terms of two specified mass velocities. The time-dependent fluctuations in wall temperature are given to indicate the transition of different flow patterns and the effect of varied mass flux. In addition, boiling mechanisms are found to be strongly dependant on wall surface conditions. A comparison of the computed flow boiling in a microchannel with reentrant cavities on side walls to experimental results is performed. The cavities are shown to help to facilitate boiling nucleation, enhance the critical heat flux, and reduce the superheat for the boiling onset. Finally, the size effect of nucleation sites is analyzed and addressed, the cavity diameter and depth being carefully considered. Based on the compatible view, the optimal configuration of reentrant cavities is located.
Online Course Design Informed by Students’ Epistemic Beliefs: A Case Study of a Thermodynamics Course
Authors: Hall Simin , Amelink Catherine T. , Conn Samuel , Brown Eugene
Published: May 2012

Online offerings of abstract engineering courses such as thermodynamics provide a medium to present course material using pedagogy that employs problem-based learning (PBL). This shift requires a student-centered approach to course design and delivery that addresses several key elements in the educational setting, including students’ self-efficacy as it relates to problem-solving and students’ epistemic beliefs as they relate to interacting with peers, instructors, and instruction. This paper reports results from a mixed-method study that collected data useful in design of an online course focused on teaching problem solving skills among students. The data were collected through qualitative and quantitative methods used to determine how students approach problem solving, the role of instructor in facilitating problem solving, and the role of peers and students’ use of technology as it relates to accomplishing course work related to problem solving. Results reveal that students are confident in their problem-solving skills but rely primarily on the instructor to show them how to solve problems. Analysis and discussion focus on how to change the manner in which the content of the course is designed and presented to improve students’ self-efficacy in problem solving and students’ epistemic beliefs through active engagement with materials and collaboration with peers and instructor.
Experiments on Liquid Droplet Impinging Erosion
Authors: Yamagata Takayuki , Fujisawa Nobuyuki , Ikarashi Akiharu , Hama Daichi , Takano Tsuyoshi
Published: May 2012

In the present paper, liquid droplet impinging erosion is studied using a newly developed spray-jet-type apparatus to evaluate the erosion rate of aluminum material due to the droplets having a diameter of tens of micrometers. In order to characterize the droplet properties, such as velocity, diameter and number density, optical measurements have been introduced using PIV, direct imaging and light extinction method, respectively. While, the erosion rate of aluminum material is evaluated using the spray-jet apparatus. The present measurements indicate that the non-dimensional erosion rate agrees closely with the previous result obtained at larger droplet diameters. However, the threshold velocity was estimated to be larger than that of the previous result, suggesting the influence of droplet diameter on the threshold velocity.
Two-Phase Flow Simulation of a Non-Boussinesq Density Current
Authors: Mehdizadeh A. M. , Bazargan-Lari M. R. , Mansoori A. , Mehdizadeh A.
Published: May 2012

Boussinesq approximation was widely used in the previous studies to model dilute density or turbidity currents. This approximation was helping to simplify the governing equations and employing a single phase simulation of density currents. In contrast to the general approach of the previous researches who tried to avoid two-phase flow simulation, in this study the two-phase simulation of density current is performed to compare the solution based on the non-Boussinesq behaviour of the fluid with that assuming the Boussinesq approximation. The above goal has been achieved by employing the mixture model for the two-phase flow simulation. The geometry of study is based on a long shallow channel in which a high speed jet of salt-water entering the stilling fresh water via the sluice gate. Different turbulence models results have been compared with the experimental data in order to verify the best results. Also, results of two-phase simulation have been compared to those obtained by the Boussinesq approximation, results show that the two-phase simulation provides superior prediction compared to the conventional single phase flow simulation.
A New Device to Quantify Human Trunk-Control Measurements
Authors: Plotkowski Alex , Barakat Nael
Published: May 2012

When helping in the rehabilitation of stroke and head trauma patients, physical therapists often find a need to measure the patient’s control of the muscles in their torso. This is called trunk control. Currently, there are two options for the measurement of trunk control. The first is qualitative analysis by the physical therapist, and the second is large, expensive equipment that measures the patient’s balance. The goal of this project was to create a low cost, quantitative means of measuring trunk control. The device used accelerometers placed on the back of the patient’s neck to measure the angle of the patient’s torso from vertical, as compared to acceleration due to gravity, in both left to right and forward to backward directions. The data taken from the accelerometers is stored on a micro-SD card, which is then inserted into a personal computer and analyzed using software built in the lab. The software produces a graphical representation of the data and displays useful calculations. During the course of the project, careful consideration had to be taken to stay within the bounds of professional ethics from a biomedical point of view. This included restricting the testing of the device and taking patient safety as a primary consideration during the entirety of the design process. Future iterations of the device will include technical and aesthetic improvements based on feedback from a group of physical therapy students who are currently testing the quality of the device’s measurements as well as its integration into a clinical setting. Additionally, a group of business students are constructing a business plan for the marketing and sales of this product.
Micro Texture Dependence of Both the Mechanical and Electrical Properties of Electroplated Copper Thin Films Used for Interconnection
Authors: Murata Naokazu , Saito Naoki , Tamakawa Kinji , Suzuki Ken , Miura Hideo
Published: May 2012

Both mechanical and electrical properties of electroplated copper thin films were investigated experimentally with respect to changes in their micro texture. Clear recrystallization was observed after the annealing even at low temperature of about 150°C. The fracture strain of the film annealed at 400°C increased from the initial value of about 3% to 15%, and at the same time, the yield stress of the annealed film decreased from about 270 MPa to 90 MPa. In addition, it was found that there were two fatigue fracture modes in the film annealed at the temperatures lower than 200°C. One was a typical ductile fracture mode with plastic deformation and the other was brittle one. When the brittle fracture occurred, the crack propagated along weak or porous grain boundaries which remained in the film after electroplating. The brittle fracture mode disappeared after the annealing at 400°C. These results clearly indicated that the mechanical properties of electroplated copper thin films vary drastically depending on their micro texture. Next, the electrical reliability of electroplated copper thin film interconnections was discussed. The interconnections used for electromigration (EM) tests were made by damascene process. The width of the interconnections was varied from 1 μm to 10 μm. An abrupt fracture mode due to local fusion appeared in the as-electroplated films within a few hours during the test. Since the fracture rate increased linearly with the increase of square of the applied current density, this fracture mode was dominated by local Joule heating. It seemed that the local resistance of the film increased due to the porous grain boundaries and thus, the local temperature around the porous grain boundaries increased drastically. On the other hand, the life of the interconnections annealed at 400°C was improved significantly. This was because of the increase of the average grain size and the improvement of the quality of grain boundaries in the annealed films. The electrical properties of the electroplated copper films were also dominated by their micro texture. However, the stress migration occurred in the interconnections after the annealing at 400°C. This was because of the high residual tensile stress caused by the constraint of the densification of the films by the surrounding oxide film in the interconnection structures during the annealing. Finally, electroplating condition was controlled to improve the electrical properties. Both the resistance of electromigration and electrical resistivity were improved significantly. However, electromigration of copper atoms still occurred at the interface between the electroplated copper and the thin tantalum (Ta) layer sputtered as base material. Therefore, it is very important to control the crystallographic quality of electroplated copper films and the interface between different materials for improving the reliability of thin film interconnections.
Curving Simulation of Ultralow-Floor Light Rail Vehicles With Independently Rotating Wheelsets
Authors: Sugiyama Hiroyuki , Yamashita Shunpei , Suda Yoshihiro
Published: May 2012

In this investigation, curving performance of an ultralow-floor light rail vehicle (LRV) is investigated. To this end, LRV model with independently rotating wheels is developed and used for full vehicle dynamics simulations. A parallel computing algorithm for railroad vehicle simulations is implemented for reducing overall CPU time associated with wheel/rail contact search and force evaluations. Using the numerical procedure developed in this investigation, curving performances of an ultralow-floor LRV are discussed. Steady state lateral forces on small radius curved track are compared between the full vehicle simulation and the on-track test. Furthermore, it is demonstrated that use of friction modifiers on inner rail is effective for reducing lateral contact forces of LRV with independently rotating wheels on tight radius curved track.
Sensitivity Analysis of a Biomass Fired Stirling Engine Combined Cooling, Heating, and Power System for a Small Office Building
Authors: Harrod James C. , Mago Pedro J.
Published: May 2012

Over the past decade, rising energy demand and cost have created a surge of interest in alternative methods of power generation. As a result, the implementation of combined cooling, heating, and power (CCHP) systems has become a potential candidate for substitution in conventional power generation. The evaluation of a CCHP system must be based on its potential for savings in cost and primary energy reduction. In general, a CCHP system includes several components to satisfy the electric and thermal demands of the facility. These components include the prime mover, heat recovery system, auxiliary boiler, absorption chiller, heating coil unit, and hot water system unit. In practice, the most common prime mover used in CCHP technology is the internal combustion engine, which is limited by low thermal efficiency and poor emissions. Hence, this paper proposes the use of a Stirling engine prime mover that makes use of waste wood chips for fuel. In addition to the standard CCHP components, the Stirling engine houses heat exchangers to aid heat addition and rejection processes. These heat exchangers must be considered along with the other components when analyzing energy requirements. The goal of this study is to determine how the operational characteristics of a constant output biomass-fired Stirling CCHP system are affected by the performance of the individual CCHP system components. The results of this sensitivity analysis are useful in determining the most important parameters to be considered when implementing and designing the system. Results suggest that fuel cost, engine efficiency, engine size, chiller efficiency, and the Stirling engine’s hot side heat exchanger play the most important roles in the CCHP system operational cost. For example, the results show that increasing the engine size leads to increases in primary energy. In addition, an optimum engine size is suggested for cost savings, with smaller and larger engines both leading to increases in operational cost.
FEM Analysis on Damage Layer in Wire Saw Cutting Single Crystal Silicon
Authors: Zhang Jianhua , Zhang Xiaojun , Jen Tien-Chien , Liu Jiafu , Yen Yi-Hsin
Published: May 2012

With the rapid development of large scale integrated circuit (IC), there are strong demands for silicon wafers developing towards large diameter and thin wafer direction. The fixed-abrasive diamond wire saw (FAWS) technology is often used to cut the large diameter silicon. Currently, the detection of damage layers mainly depends on experiments, which are not only costly and time-consuming, but also would cause the new damage during the detection process, in the FAWS technology. In this paper, the damage layer of the material is studied by using the multi-grain finite element method. The interaction of grains and the whole wire cutting process are analyzed by means of the coupling shear stress field, which got by the simulation results. The influence of the process parameters on the damage layer of the crystal silicon is analyzed by FEM.
Mathematical Model of the Cooling of a Plastic, Thermoformed Part
Authors: Aidich Thomas M. , Jen Tien-Chien , Yen Yi-Hsin
Published: May 2012

This paper presents research into the mechanism involved in the cooling of a plastic thermoformed part after it is formed onto a mold. The intent of this research is to develop a simple and practical mathematical model useful to small thermoforming companies without a large engineering staff that describes the transient heat conduction of the cooling process. The model should also be able to predict the temperature distribution within the thickness of the part during the cooling. This mathematical model, which began with simplified boundary conditions, was then compared to experimental cooling data and modified accordingly to properly fit that data and the actual boundary conditions of the cooling part. The research began by examining the cooling of a series of high molecular weight polyethylene thermoformed side panels for plastic, portable restrooms. These parts where chosen for this preliminary research because of their very simple, flat geometric shape that lends them to being modeled as simple plane walls in transient conduction. The shape of the parts also leads to near constant thickness over the vast majority of the part. Using the model of a plane wall in transient conduction, the governing partial differential equation was solved for two possible boundary conditions on the mold side of the part: constant imposed surface temperature and constant imposed surface heat flux. These two solutions were then compared to experimental data gathered on the temperature profile of the free surface of the part during a production environment. After the experimental data and simple mathematical models were compared the necessary changes to the assumed mold side boundary condition was made to adjust the mathematical model to the experimental data. The research found that the use of simple boundary conditions at the mold side of the part is incorrect. Neither the constant imposed surface temperature nor the imposed surface heat flux boundary conditions fit the data. Initial analysis of the experimental data showed that a time of 30 seconds into the cooling cycle an apparent change in that boundary condition occurs for the part and mold used to gather the data. Further analysis showed that the boundary condition begins as a constant surface heat flux and then changes to an imposed surface temperature that decays exponentially to the initial mold surface temperature. Using this boundary condition, a revised mathematical was developed that match the experimental data very well. The error of the new model compared to the experimental was less than 1.5% for all times during the cooling cycle.
Heavy Equipment Controls Guarding to Prevent Unintended Contact and Inadvertent Machine Motion (A Mechanical and Human Factors Analysis)
Authors: Ferrone Christopher W.
Published: May 2012

Powerful earth moving and other heavy equipment should only move when commanded by the operator. Equipment which may move as a result of the operator contacting one of the controls unintentionally can lead to property damage and bodily injury. This situation can openly occur without the operator realizing it. The general scenarios for unintended control contact are; operator entry / exit from the machine, operator seated but “leans” during distraction, operator seated but stands up and operator reaches through window for controls. The purpose of this paper, though mechanical and human factors analysis, is to inform equipment manufacturers, dealers and machine operators of this hazard. Additionally, it will provide design alternatives and concepts that will assist in mitigating and/or preventing these injuries altogether.
An In-Depth Study on the Mechanical and Thermal Properties of Nanoclay Reinforced Polymers at Various Temperatures
Authors: Bayar Selen , Delale Feridun , Liaw Benjamin , Li Jackie Ji , Chung Jerry , Dabrowski Matthew , Iyer Ramki
Published: May 2012

In this study, the mechanical properties of nanoclay reinforced polymeric resins are investigated at various temperatures. In recent years there has been heightened interest to develop nanoclay reinforced composites due to their superior performance compared to neat resins at high temperatures under various loading conditions, including impact. First, polypropylene (PP) resin specimens reinforced with varying weight fractions of nanoclay (0%, 1%, 3%, 6% and 10%) some instrumented with strain gages, were subjected to tensile loads and the stress-strain curves were obtained to determine the mechanical properties of the nanocomposite. Extensive experimental data were obtained. The results indicate that as the weight percentage of nanoclay increases, the strength and stiffness of the resulting nanocomposites also increase. Most of PP specimens exhibited significant deformation (more than 100%) and did not break. High temperatures have a deleterious effect on the strength and stiffness of nanoclay reinforced PP specimens. However, the addition of nanoclay, somewhat mitigates the deterioration of these properties. At lower temperatures the material stiffens, has higher strength and becomes more brittle as failure occurs at much lower strains. Also the tests using different PP resins indicate that the type of resin used has significant effect on the properties of the nanocomposite. A micromechanics model based on the Mori-Tanaka formulation was used to predict the results obtained experimentally. The comparison of theoretical/numerical and experimental results indicates that the Mori-Tanaka formulation may be a useful tool in predicting these properties.
A Case Study of Energy Saving by CCHP Technology in a Hospital
Authors: Okamoto S.
Published: May 2012

This paper describes a study that starts with an analysis of typical energy demand profiles in a hospital setting followed by a case study of a CCHP system. The CCHP idea is of an autonomous system for the combined generation of electrical, heating, and cooling energy in a hospital. The driving units are two high-efficiency gas engines that produce the electrical and heat energy. A gas engine meets the requirement for high electrical and heating energy demands; a natural gas-fuelled reciprocating engine is used to generate 735 kW of power. In our case, the electrical energy was used only in the hospital. A deficit in electricity can be covered by purchasing power from the public network. Generated steam drives three steam-fired absorption chillers and is delivered to individual heat consumers. This system can provide simultaneous heating and cooling. No technical obstacles were identified for implementing the CCHP. The typical patterns for driving units of CCHP were decided by the hourly energy demands in several seasons throughout the year. The average ratio between electric and thermal loads in the hospital is suitable for CCHP system operation. An analysis performed for a non-optimized CCHP system predicted a large potential for energy savings and CO2 reduction.
Application Study of BCHP System With Absorption Heat Pump of an Urban Original Sewage Source
Authors: Zhao X. L. , Fu L. , Zhang S. G. , Zhu J. Z. , Huang B. M. , He T.
Published: May 2012

A critical issue for BCHP (Building combined cooling heating and power) system is the efficient integration of power generation equipment with different heat utilization technologies. A BCHP system with an urban original sewage source absorption heat pump is proposed. The system is composed of an internal combustion engine, a water-water heat exchanger, a flue gas driven absorption heat pump, a filth block device, a wastewater heat exchanger, and other assistant facilities, such as pumps, fans, and end user devices. In the winter, the waste heat of the flue gas is used to drive absorption heat pump to recover the waste heat of sewage source and the flue gas, and in the summer, the waste heat of the flue gas is used to drive absorption heat pump for cooling, and the heat load of the building is removed to the sewage. In the paper, this kind of system was designed according to the energy consumption of the buildings, and the overall performance of the system in the heating and cooling mode was studied, and the energy efficiency level was analyzed. It is shown that the system is the efficient integration of clean energy and waste heat resource, and the energy efficiency of the system could be improved by 18.5% compared with the conventional BCHP systems.
Improvement in Surface Quality With Molybdenum Disulphide as Solid Lubricant in Turning AISI 4340 Steel
Authors: Gaur A. P. S. , Agarwal Sanjay
Published: May 2012

It is generally considered that the heat produced during the machining process is critical in terms of workpiece quality. Relatively high friction effects in machining cause heat generation that can lead to poor surface quality of a machined part. Coolant and lubrication therefore play decisive roles in machining. Cutting fluids are introduced in the machining zone to improve the tribological characteristics of machining processes and also to dissipate the heat generated, but they are partially effective within a narrow working range. In addition, they also create some techno-environmental problems. Solid lubricant assisted machining is a novel concept to control the machining zone temperature without polluting the environment. Solid lubricant, if employed properly, could control the machining zone temperature effectively by intensive removal of heat from the machining zone. Therefore, the aim of present study is to investigate the effect of molybdenum disulphide as solid lubricant in the zone of machining. Experiments were carried out to investigate the role of solid lubricant such as molybdenum disulphide on surface finish of the product in machining a AISI 4340 steel by coated carbide inserts of different tool geometry under different cutting conditions. Results indicate that the effectiveness of solid lubricant is substantial through the experimental domains.
The Theoretical Frequency Response of an Over-Center, Pressure-Controlled, Axial Piston Pump
Authors: Mehta Viral S. , Manring Noah D.
Published: May 2012

Axial piston pumps are ubiquitous in the hydraulic systems employed on various off-highway machines such as hydraulic excavators or wheel-loaders. These pumps exhibit a fairly slow response to the commanded input resulting in a slow response of the work tool (implement or transmission) as well, which is undesirable to machine operators and also slows down the machine’s productivity. Hence it is very important to understand the factors affecting the dynamic pump response. Much of the earlier work aims at understanding the steady state behavior of the pump control system using linear transfer function analysis. A closed-form solution for the dynamic frequency response has not been reported in previous research. This work presents the analysis of a variable displacement pump with an adjustable swash-plate for the purposes of identifying parameters that contribute to the response characteristics of the pump. The full model of the pump involves a seventh order model including a large number of non-linear terms. Hence a reduced order model has also been derived for calculating the frequency response of the pump in the closed form and it is shown that the design parameters that impact the frequency response most heavily are the actuator area, the swash-plate moment arm, and the flow gain of the four-way valve. As it turns out, an increased frequency response of the pump may be most readily achieved by increasing the charge pressure which in turn reduces the required actuator area and increases the flow gain of the valve.
Analysis and Characterization of Surface Plasmon Enhancement of Light Absorption in Organic Solar Cells by the Transfer Matrix Method
Authors: Rami´rez Francisco V. , Guzma´n Amador M.
Published: May 2012

Surface plasmons enhanced light absorption in organic solar cells based on a photoactive poly(2-methoxyl-5-(2-ethyl-hexyloxy)-1.4-phenylenevinylene):(6.6)-phenyl-C61-butyric-acid-methylester (MEH-PPV:PCBM), is studied by a computational model based on the transfer matrix method (TMM). Two physical situation with and without the bulk heterojunction film are considered and modeled on a 2D array of silver nanoparticles with a diameter of 40 nm embedded in a 50-nm-thick layer. The numerical simulation results that include optical properties in the wave length range of 350 and 750 nm, present qualitative and quantitative good agreement with previous results obtained by Duche et al (2009) in both conditions. Optical absorption results for incident light at an oblique angle of incidence are also obtained, with the purpose of determining the effect of the angle of incidence on the absorption properties.