bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Planning and Economic Evaluation of Small Scale Cogeneration System
Authors: Kwak Ho-Young , Oh Si-Doeck
Published: April 2008

Cogeneration plants, which simultaneously produce electricity and heat energy have been introduced increasingly for commercial and domestic applications in Korea because of their energy efficiency. The optimal plant configuration of a specific commercial building can be determined by selecting the size and the number of cogeneration systems, auxiliary equipment based on the annual demands of electricity, heating and cooling. In this study, a mixed-integer, linear programming, utilizing the branch and bound algorithm was used to obtain optimal solution. Both the optimal configuration system equipment and the optimal operational mode were determined based on the annual cost method for installation of a cogeneration system to a hospital and a group of apartments in Seoul, Korea. In addition, the economic evaluation for the optimal cogeneration system depending on the fuel tariff system was calculated. A short payback period and a high internal rate of return on the initial investment were found to be essential for the adoption of cogeneration plants to hospitals and apartments.
The Mesoscopic Simulation on the Structures of the Surfactant Solution Using Dissipative Particle Dynamics
Authors: Kim Ki Young , Byun Ki-Taek , Kwak Ho-Young
Published: April 2008

With a simple model of surfactant which consists of hydrophilic head group and hydrophobic tail groups connected by harmonic springs, structural change of the association structures of surfactant in an aqueous solution was studied using the dissipative particle dynamics (DPD) simulation. The effect of the hydrophilic interaction between the head and water molecules and the hydrophobic interaction between the tail and water molecules and the head and tail on the structural change of the association structures was studied. Simulations show that proper value of these interaction parameters could yield desirable change of the association structure depending on the concentration of the surfactant. For example, a hexagonal structure appears when the volume fraction of surfactant of SDS (sodium dodecyl sulfate) becomes 25% in aqueous solution, which is in good agreement with observation.
Carbon Nanotube-Tipped Microcantilever Arrays for High Speed Biological System Testing and Imaging
Authors: Lee Eunjeong
Published: April 2008

This paper discusses the design and control of massively parallel microcantilever arrays with multi-walled carbon nanotube tips. The integrated system can make a powerful tool for imaging, sensing and 3D nanomanipulation of nanoparticles and biological samples. The microcantilever has a multi-walled carbon nanotube tip and four additional carbon nanotubes for 3D fine manipulation by electrostatic forces. The reflected light from the deflected microcantilever is collected by a position sensitive photodetector and fast readout is achieved by a time-multiplexing scheme. A distributed parameter system model has been developed to study its dynamic behavior. Simulations have been performed for the carbon nanotube tipped microcantilevers of three different dimensions to investigate their open-loop and closed-loop performances. It is shown via simulations that with carefully selected dimensions they can demonstrate an excellent capability for nanomanipulation of samples and tapping mode operation for imaging under a simple PID controller.
Measurement and Analysis of Noise Characteristics for Diesel Engine
Authors: Liu Guangpu , Pan Hongxia , Huang Jinying
Published: April 2008

The vehicle interior noise is mainly caused by irregularity of road, engine and transmission. So it is important to study on the noise characteristics for diesel engine and identify the main noise source and investigate the effective methods to control noise. In this paper, by using the measurement and analysis system, we measured the sound pressures levels and their curves the noise of a military diesel engine, then made spectral analysis and coherence analysis. The results provide bases for low noise design of this diesel engine.
Accuracy of a Coherent Doppler Lidar for the Urban Boundary Layer Measurements
Authors: Li Xiangyi , Princevac Marko , Calhoun Ronald
Published: April 2008

A large field experiment, dubbed Joint Urban 2003 (JU2003), took place in Oklahoma City in July 2003. The key component of this experiment was to study the movement of inert tracer gases through the urban environment. A large variety of atmospheric measurement systems have been deployed during the experiment - providing unprecedented opportunities to investigate questions related to the urban flows and dispersion. Two Doppler lidars were deployed with the main purpose to give a deeper insight to the coupling between the free-stream wind and urban centers. The Coherent Doppler lidar technology provides an effective way for remote measurements of the mean winds and turbulence, however, lidars are prone to the noise related measurement errors. Generally, the accuracy of the lidar measurements decreases with the increasing distance due to the weakening of the signal-to-noise ratio (SNR). The first step in the analysis was the calculation of power density spectra of the radial velocity for each range gate. During the experiment the sampling rates of 10 and 5 Hz corresponding to the Nyquist frequency of 5 and 2.5 Hz, respectively, were used. In order to alienate the effect of estimation errors due to the high frequency noise, the constant part of spectrum was examined. The estimate variance as well as standard deviation of estimation errors were determined from the integral of this constant spectrum. To give more accurate description of estimation errors for the cases far away from the lidar where the noise becomes significantly large, the data was filtered using sample averaging technique. This study emphasizes the situations when the lidar measurements should be taken with caution. The recommendations for noise reduction and filtering techniques are given.
Bio-Droplets Self-Mixing by Pattern Surface
Authors: Yu Chih-Sheng , Lin Ming-Yu , Hu Yi-Chiuen , Hu Heng-Tsang , Chou Hsiao-Yu
Published: April 2008

In this paper, we characterize a gradient of surface tension by patterning surface that containing radiative texture and hydrophobic behavior. The protein absorption is a challenge on the hydrophobic surface; we describe a method to manipulate the blood-droplet moving on the hydrophobic surface without stick effect. The phenomenon of droplet self-motion is due to hysteresis effect that triggered the droplet to move with a velocity of about 20mm/s. Mixing of two droplets is experimentally in this device and mixing time less than ten seconds.
Optimized Thermal Design for LED Back-Light Unit (BLU)
Authors: Ghim Joongel , Chung Kilyoan , Jeong Giho , Yang Siyoung , Kim Changsung Sean
Published: April 2008

This paper presents thermal optimization of back-light unit (BLU) using a Design of Experiment (DOE) used in conjunction with numerical simulation. The technique is used to optimize multiple aspects of thermal performance for various parameters that are all variable for heat sink and fan. The outcome of this optimization provided with reducing the number of empirical prototype cycles and experiments, and cost of performing these processes. Therefore, it gave a more mature and viable cooling solution. Using DOE technique, thermal design for BLU was optimized and applied to the model.
Feedforward Neural Network Compensation and State Estimation in Suppressing Mechanical Vibrations in a PMLSM
Authors: Hirvonen M. , Yousefi H. , Handroos H.
Published: April 2008

Neural networks have been proposed for the control and compensation of electromechanical systems during the past decade. In this study, a neural network compensator for suppressing mechanical vibrations in a Permanent Magnet Linear Synchronous Motor (PMLSM) application is postulated. The linear motor itself is controlled by a conventional PI-velocity controller, and the vibration of the flexible mechanism on the linear motor is suppressed from an outer control loop using a compensation signal from a feedforward neural network. The neural network compensation is based on feedback, which is produced from the acceleration estimation of a moving mass by using the Kalman Filter. The algorithm is first designed in the simulation program, and then implemented in the physical linear motor using a DSP application. The results of the responses are presented in this paper. The proposed method is robust in all conditions and satisfies all control evaluation criteria.
Vehicle Design, Simplifying the CAD Process
Authors: Tucker Craig , Brown Robert D.
Published: April 2008

It is a feature of several courses that students undertake a military vehicle design and costing exercise. Many of the students do not have engineering or technical backgrounds and are unfamiliar with conventional engineering techniques of graphical representation. Learning a complex CAD package solely for this exercise is inappropriate, it would require considerable time to be found in the timetable and it is highly unlikely that the student would use this skill again. As a result Cranfield University has developed a user friendly design package which allows the students to design and build their vehicle by selecting suitable vehicle components from a drop down menu and arranging them on the workspace. In summary, this design package has greatly reduced the design time. It has helped students to appreciate the problems related to accommodating major subassemblies and their packaging and has allowed compromises and trade-offs to be understood and addressed rapidly.
Modelling Conduction and Radiation in the Reactive Porous Bed of the Gasifier
Authors: Sharma Avdhesh K. , Ravi M. R. , Kohli S.
Published: April 2008

This paper presents the heat transfer model for the gasifier to predict the temperature profile in the bed using the single zone sub-model. The single zone sub-model is also used to verify the correctness and to demonstrate the effect of various parameters for e.g. solid/fluid flow, temperatures of inflow/outflow control volume (CV), heat generation/absorption and with/without heat loss. The study shows that solid/fluid flow, inflow CV temperature and heat generation/absorption within the CV of interest are the strong influencing parameters, whether, the outflow CV temperature has insignificant effect on the temperature values of the CV of interest. The six similar zones correspond to preheating, drying, pyrolysis, oxidation, reduction and annular jacket zone are also coupled in order to predict the temperature profile in the gasifier bed. The simulation result shows that temperature of the down stream zones are more sensitive to heat generation in the bed as compared to upstream zone temperature, while the increase in gas flow rate resulting into the decrease in temperature profile depending upon the values of heat generation/absorption in bed is being fixed.
Multiphase Flow Separators in Reduced Gravity
Authors: McQuillen John , Sankovic John , Hall Nancy Rabel
Published: April 2008

Gas phase and liquid phase separation is necessary for one of two reasons. First, system-critical components are designed to specifically operate in a single phase mode only. Pumps, especially centrifugal pumps, lose their prime when gas bubbles accumulate in the impellor housing. Turbines and compressors suffer from erosion problems when exposed to vapor laden with liquid droplets. The second reason is that system performance can be significantly enhanced by operating in a single phase mode. The condensation heat transfer coefficient can be enhanced when the liquid of an entering two-phase stream is stripped thus permitting initial direct contact of the vapor with the cold walls of the condenser. High efficiency and low mass Environmental Control and Life Support Systems invariably require multiphase processes. These systems consist of water filtration and purification via bioreactors that encounter two phase flow at the inlets from drainage streams associated with the humidity condensate, urine, food processing, and with ullage bubble effluent from storage tanks. Entrained gases in the liquid feed, could have deleterious effects on the performance of many of these systems by cavitating pumps and poisoning catalytic packed bed bioreactors. Phase separation is required in thermal management and power systems whereby it is necessary to have all vapor entering the turbine and all liquid exiting the condenser and entering the pump in order to obtain the highest reliability and performance of these systems. Power systems which utilize Proton Exchange Membrane Fuel Cells generate a humidified oxygen exit stream whereby the water vapor needs to be condensed and removed to insure reliable and efficient system operation. Gas-liquid separation can be achieved by a variety of means in low gravity. Several active and passive techniques are examined and evaluated. Ideally, a system that functions well in all gravity environments that the system experiences is a requirement
Development of Membrane Micro Embossing (MeME) Process for Self-Supporting Polymer Membrane Microchannel
Authors: Ikeuchi Masashi , Ikuta Koji
Published: April 2008

In this work, we have successfully fabricated self-supporting polymer membrane microchannels with width of 50μm, depth of 50μm, and wall thickness of ~5μm. To fabricate this self-supporting polymer membrane microchannel, we have developed novel micro fabrication process named “membrane micro embossing (MeME)”. In this process, a thin (~μm) thermoplastic polymer membrane set between a master mold and a deformable support substrate is heated to glass transition temperature, and pressed to fit the membrane onto the mold surface. By heat-sealing the embossed membrane with another planar membrane, we can fabricate sealed membrane microchannels. This membrane microchannel surrounded by only thin membrane walls will provide a powerful platform for micro-scale biological and chemical analysis.
Numerical and Experimental Investigation of Flow Through Vane Swirlers
Authors: Thundil Karuppa Raj R. , Ganesan V.
Published: April 2008

This paper is concerned with the computational and experimental study of steady flow through vane swirlers for various vane angles from 15° to 60° in steps of 15°. In the computational study the geometry and meshing is done using pre-processor GAMBIT. Three dimensional flow within the geometry and through the swirler has been simulated by solving the appropriate governing equations viz. conservation of mass and momentum using FLUENT code. Turbulence effects are taken care of by the Reynolds stress model for high swirls and standard k-ε model for low swirls. The effects of vane angle on flow characteristics have been studied. A parametric study is done for a 45° vane swirler to investigate the effect of number of vanes. Experimental results of axial velocity profiles downstream of the swirler are found to be in close agreement with the numerical results. The total pressure loss factor, maximum reverse velocity and maximum reverse mass flow for each swirler are determined
Model Based Development of an Integrated Sensor-Actuator System for Online Quality Monitoring in Ultrasonic Wire Bonding
Authors: Bro¨kelmann Michael , Wallaschek Jo¨rg , Hesse Hans J.
Published: April 2008

Quality monitoring in microelectronics becomes more and more important because of the constantly rising complexity and miniaturization of modern microelectronic devices. This paper describes a model based method for online quality monitoring in ultrasonic wire bonding. This new approach aims to reconstruct the metallophysical processes within the bonding zone by the aid of a validated analytical model of the bonding system. The model comprises a 2-DOF electromechanical analogous circuit representing the ultrasonic transducer, a phase-locked-loop controller for frequency control and time varying spring-damper elements representing the bond process. It will be shown how faulty bonds can clearly be identified by this method.
Predicting Turbulent Boundary Layer Wall Pressure Fluctuations in Adverse Pressure Gradients
Authors: Aldrich Frank J.
Published: April 2008

A physics-based approach is employed and a new prediction tool is developed to predict the wavevector-frequency spectrum of the turbulent boundary layer wall pressure fluctuations for subsonic airfoils under the influence of adverse pressure gradients. The prediction tool uses an explicit relationship developed by D. M. Chase, which is based on a fit to zero pressure gradient data. The tool takes into account the boundary layer edge velocity distribution and geometry of the airfoil, including the blade chord and thickness. Comparison to experimental adverse pressure gradient data shows a need for an update to the modeling constants of the Chase model. To optimize the correlation between the predicted turbulent boundary layer wall pressure spectrum and the experimental data, an optimization code (iSIGHT) is employed. This optimization module is used to minimize the absolute value of the difference (in dB) between the predicted values and those measured across the analysis frequency range. An optimized set of modeling constants is derived that provides reasonable agreement with the measurements.
Assisted Passive Snake Robots:Conception and Dynamic Modeling Using Kane’s Method
Authors: Pendar Hodjat , Vossoughi Gholamreza , Khoshnood Atefeh , Poursamad Amir
Published: April 2008

In this paper conception and dynamic modeling of a snakelike robot with passive wheels and compliant joints is investigated. The proposed robot has the ability to follow a so-called Serpenoid curve passively by using an appropriate set of initial conditions. Introduction of a unique structure at each joint enables the robot to achieve passive motion. A torsional spring is used in series with an actuator between each two consecutive links. Using wheels at the middle of each link imposes many non-holonomic constraints to the system. These constraints reduce the degrees of freedom of the system to only two. Due to the existence of these non-holonomic constraints, dynamic equations governing the locomotion of the articulated robot are obtained using Kane’s method. This technique is highly effective in reducing the complexity of the dynamic equations and results in significant reduction of the simulation time. Comparing the number of mathematical operations and the simulation time needed in the Kane’s and Lagrange’s methods illustrates the considerable difference.
Design and Control of a New Tendon-Driven Exoskeletal Lower Body Power Assistive Device
Authors: Kong Kyoungchul , Jeon Doyoung
Published: April 2008

Recently the exoskeletal power assistive equipment which is a kind of wearable robot has been widely developed to help the human body motion. For the elderly people and patients, however, some limits exist due to the weight and volume of the equipments. As a feasible solution, a tendon-driven exoskeletal power assistive device for the lower body, and caster walker are proposed in this research. Since the caster walker carries the heavy items, the weight and volume of the wearable exoskeleton are minimized. The fuzzy control is used to generate the joint torque required to assist motions such as sitting, standing and walking. Experiments were performed for several motions and the EMG sensors were used to measure the magnitude of assistance. When the motion of sitting down and standing up was compared with and without wearing the proposed device, the 27% assistance was acquired.
A Stress Analysis and Strength Estimation of Stepped Lap Adhesive Joints Under Static and Impact Tensile Loadings
Authors: Sawa Toshiyuki , Ichikawa Kohei
Published: April 2008

The stress variations and stress distributions in stepped-lap adhesive joints of dissimilar adherends under impact tensile loadings were analyzed in elastic range using three-dimensional finite element method. The impact loadings were applied to the lower adherend by dropping a weight. The stress distributions in stepped-lap adhesive joints of dissimilar adherends under static tensile loadings were also analyzed using FEM. The effects of Young’s modulus of the adherends, the adhesive thickness and the number of butted steps of adherents ware examined under both impact and static loadings. As the results, The maximum value of stress σ1 increased as Young’s modulus of the adherends increased for the impact loadings. The maximum value of stress σ1 increased as the numbers of steps in the adherends increased for the static loadings. In addition, the experiments to measure the strain response of joints subjected to impact tensile loadings were carried out using strain gauges. A fairly good agreement was found between the numerical and the measured results concerning the strain responses.
Real Time Monitoring of Vehicle/Track Interaction
Authors: Najikovsky Boris , Kesler Kevin , Stevens Jeffrey
Published: April 2008

ENSCO, Inc. has developed the next generation of real time Vehicle Track Interaction (V/TI) Monitoring system. The system provides continuous measurement of car body, truck motions and axle impacts. Software detects various acceleration events, tag them with GPS time and location information, and deliver the data to a central processing system through the latest Code Division Multiple Access (CDMA) wireless communication network. Upon delivery, the information is automatically tagged with milepost and subdivision or other geographic reference and loaded into an enterprise database management system. The data is available in near real time via the web on maps of the track and track infrastructure where users have the option of generating tabular reports or viewing the actual waveform of the acceleration event. In addition, the system offers real time pager and email notifications of predefined user events. This system automatically provides real time monitoring and detection of track profile and alignment problems, battered joints, rail-end mismatch, misaligned switches and damaged frogs. The information generated by this system helps railroads prioritize maintenance for these track anomalies that can cause equipment or lading damage. The location information picked up by the system allows railroads to navigate back to the track areas for follow up remedial actions or enhance track maintenance planning decisions. There are over 60 systems in operation on passenger and freight railroads. This paper will address the technology behind the monitoring, the events detected in the field, and how the system can be used to supplement traditional track inspection technologies.
Design of a Biopsy Module for the Capsule Type Endoscope
Authors: Kong Kyoungchul , Jeon Doyoung
Published: April 2008

Recently the technology of capsule endoscopy has developed dramatically and many researchers are making efforts to combine surgical function into the capsule type endoscope. In this paper, the micro biopsy module which is a part of the capsule endoscope is proposed. The proposed module is less than 2 mm in thickness and has a diameter of 10 mm. It consists of a trigger with paraffin block, rotational tissue-cutting razor with a torsion spring and a controller. This module makes it possible for the capsule endoscope to obtain a sample tissue inside the small intestine which can not be reached by a conventional biopsy device. Through dedicated experiments, tissue samples were successfully extracted using the proposed biopsy module and the cells in the samples were extracted and tested by a microscope.
Modeling of a Partial-Flow, Diesel, Lean NOx Trap Systems
Authors: Midlam-Mohler Shawn , Guezennec Yann
Published: April 2008

Lean NOx Traps (LNTs) have shown promise for Diesel applications; however, production implementation in vehicles poses a number of challenges. Much of the literature reports on LNT systems in which the catalyst always receives the full flow of exhaust from the engine, referred here as full-flow regeneration systems. Another implementation of the LNT is one in which the exhaust can be partially or fully diverted from the catalyst to allow local introduction of the necessary reductants for regeneration. The physical aspects of one such system, as well as a control-oriented model are presented with experimental validation. In the system described here, the exhaust flow is diverted around the catalyst during regenerations. In the low exhaust flow through the catalyst, reductant is added (Diesel fuel typically) which provides the rich conditions for regenerating the trap. This allows the engine to continue to run in normal lean mode, which overcomes one of the major challenges for full-flow regeneration systems. Successful regeneration with liquid Diesel fuel is strongly dependent on catalyst temperature, which is addressed by proper thermal management of the system through the addition of fuel prior to regeneration. In this paper, both component level and vehicle level simulations are presented in terms of fuel economy versus NOx reduction. Several different system configurations and control strategies are compared.
Thermal Analysis on Filling Process in Hydrogen Tank
Authors: Koshimizu Takao , Kasao Daisaku , Takata Yasuyuki , Monde Masanori
Published: April 2008

When hydrogen is filled into a hydrogen tank, it is considered that the gas temperature in the tank rises considerably because the gas is pressurized to very high pressure. If the ultimate pressure is constant, the gas temperature is influenced by the heat exchange between the gas and the inner wall of the tank, filling time and filling methods. In this research, a numerical analysis of heat and fluid flow has been performed to investigate the behavior of pressure and gas temperature in the tank during and after the filling process when an adiabatic wall and an isothermal wall are variously arranged for each wall that composed the hydrogen tank. As a result, it is found that using an isothermal wall for the wall of the circumference is very effective to cooling of the gas in the tank. In addition, a numerical analysis considering the heat capacity of the wall and the heat exchange between the gas and the inner wall of the tank has been performed to clarify the behavior of pressure and gas temperature in the tank and wall temperature of the tank under a more realistic condition, and to compare its result with the numerical results under the condition in which an adiabatic wall and an isothermal wall are variously arranged. As a result, it is found that the behavior of pressure and gas temperature under the more realistic condition is very similar to those under the condition in which an isothermal wall is used for the wall of the circumference, and consequently when the behavior for a short time is shown, realistic behavior in the tank can be clarified even under the condition of an isothermal wall because the change in wall temperature is very small. Finally, the change in wall temperature under the more realistic condition is shown and consequently the behavior of the small increase of the wall temperature is clarified.
Real-Time Simulated Pressure Relief Valves in Physical Hydraulic Circuits
Authors: Eskola Tero , Handroos Heikki , Nishiumi Takao
Published: April 2008

The present paper deals with hardware-in-the-loop (HIL) simulation of hydraulic components and systems. The main idea is to develop hydraulics by using a simulation model of it as a part of the machine. The interface between the real and simulated parts is defined by means of pressures and flows. The proposed idea makes it possible to test a variety of design parameters of a hydraulic system or single component on-line while running the practical experimental machine. The method is demonstrated in its application to a single-stage pressure relief valve in a simple hydraulic circuit. The real valve is replaced in the circuit by a HIL simulator mimicking the dynamic behavior of the valve. Finally the dynamic responses of original pressure relief valve and the HIL simulator are compared.
Design and Fabrication of a Micro Flywheel Energy Storage System With a High-Temperature Superconductor Bearing
Authors: Kim Bongsu , Ko Junseok , Jeong Sangkwon , Lee Seung S.
Published: April 2008

A micro flywheel energy storage system with a high-temperature superconductor (HTS) bearing which is characterized by the diamagnetic effect and the flux pinning effect has been developed. The micro flywheel is made up of circumferential magnets for a motor/generator as well as concentric magnets for an HTS bearing and they are fitted into a 34-mm diameter and 3-mm thick aluminum disk. Mass and moment of inertia of the micro flywheel are 12.75 g and 1.84E−6 kgm2, respectively. For simplicity and miniaturization of the whole system, the micro flywheel directly takes torque from a planar stator, which consists of an axial flux type brushless DC motor/generator. The micro flywheel successfully rotated up to 38,000 rpm in vacuum condition as it is levitating above the stator with a gap of about 1 mm. However, there are some eddy current losses in the stator and non-axisymmetry in magnetic field causing large drag torque. In order to solve these problems, an improved magnet array in the flywheel including a Halbach array is proposed and 3D simulations have been conducted.
Ultrafast Laser Radiation and Conduction Heat Transfer in Biological Tissues
Authors: Kim Kyunghan , Guo Zhixiong
Published: April 2008

Ultrafast laser radiation heat transfer in biological tissues is governed by time-dependent equation of radiative transfer and modeled using the transient discrete ordinates method. The divergence of radiative heat flux is then obtained and used for predicting the local temperature response due to radiation energy absorption within the ultrashort time period. To this end, the lumped method is employed and heat diffusion is negligible. Both single pulse and pulse train irradiations are considered. For the single pulse irradiation, the transient radiation field is obtained and the local temperature keeps rising until a time of about 20 times of the short pulse width; and then a stable local temperature profile is reached and maintained until the start of heat conduction. For the pulse train case (104 ultrashort pulses until 1 ms), the local temperature response is an accumulation of continuous single pulses because the thermal relaxation time of biological tissues was reported in the range of 1-100 sec and is much longer than the pulse train duration (1 ms). After a stable local temperature field is achieved, the hyperbolic heat conduction model is adopted to describe the heat conduction. MacCormark’s scheme is utilized for solving the thermal wave equations. Thermal wave behavior is observed during the heat transfer process. It is found that the hyperbolic wave model predicts a higher temperature rise than the classical heat diffusion model. After several thermal relaxation times the thermal wave behavior is substantially weakened and the predictions between the hyperbolic and diffusion models match.
Theory, Simulation, and Hardware: Lab Design for an Integrated System Dynamics Education
Authors: Clark Jonathan E. , Provancher William R. , Mitiguy Paul
Published: April 2008

This article describes a series of experimental and simulation laboratory sessions that are designed to support a system dynamics course. A novel hardware setup is used in different configurations throughout the eight-lab sequence. The labs incrementally build upon themselves and culminate in the final lab with the stabilization of a coupled dynamic system. The labs augment the fundamental theory taught in class with hands-on experience using hardware and software simulations. We find that the labs that most effectively create and resolve tension between the results of physical experiments, simulation, and theory yield the most satisfying and effective lab sessions. The absence of any one of these three elements diminishes the educational value of the course. End-of-quarter lab surveys are used to quantify our findings.
Assessment of Influence and Analysis of Mechanism on the Reliability for Solder Joints of Electronic Device
Authors: Yu Qiang , Jin Jae-Chul , Abe Hirokazu , Koyama Takahiro , Shibutani Tadahiro , Shiratori Masaki
Published: April 2008

In recent years, the development of the electronic device using the semiconductor is remarkable. In current advanced technology, it has succeeded in making the package which size is almost equal to the IC chip. Moreover for miniaturization and high integration of the electronic device, it has been fined in soldered joints divisions. As a result, the strength reliability become an important problem, since the thermal fatigue fracture is generated by thermal expansion difference between package and printed-circuit board. However, it is difficult to guarantee quality during the design stage, because it is hard to know which design factors will prolong the fatigue life. So it is needed that a quantitative evaluation technique of the relation between the design change and the thermal fatigue reliability. The authors introduced a simple approach to help solving the design and development of a package system by using the SDSS (statistical design support system) and FEM (Finite Element Method) analysis. In this study, in order to improve the reliability, evaluations of the influence of various design factors on the reliability of BGA (Ball Grid Array) soldered joints were carried out. By using the total equivalent inelastic strain range obtained by FEM analysis, the sensitivity is calculated and the authors got the influence of each design factor. With the results, the design engineers can know the rate of each factors’ effect on the reliability of solder joints and they can use the results to assess the reliability of their design from the concept design stage. Consequently, it can be expected that almost reliability problems can be avoided at the beginning, and it will lead a great advantage of shortening design period and slashing costs. And this will lead design engineers to come up with more new ideas.
Dynamic Actuation of Electro-Elastic Spherical Membranes Using Dielectric Elastomers
Authors: Goulbourne Nakhiah , Mockensturm Eric , Frecker Mary
Published: April 2008

This paper presents dynamic results for spherical dielectric elastomer actuators subject to an inflating mechanical pressure and an applied voltage. Different equilibria modes arise during dynamic operation due to inertial effects. In previous work, the inertial effects have been studied for the limited case of a constant applied pressure during membrane deformation [1]. Here, novel results are presented in which the dynamic response of spherical dielectric elastomer actuators to a pressure-time loading history as well as a more realistic constant gas flow rate are considered. The results are calculated for both the damped and the zero-damped cases. The spherical membrane is assumed to follow the Mooney material model where various inflation modes arise depending on the material parameters. The range of Mooney material parameters considered, the driving pressure and the applied voltage all affect the dynamic response.
Negotiation in Agent Based Manufacturing Scheduling Using Auction Models
Authors: Wang Chun , Shen Weiming , Ghenniwa Hamada
Published: April 2008

This paper investigates issues in the application of auctions as negotiation mechanisms to agent based manufacturing scheduling. We model the negotiation environments that agents encounter as inter-enterprise environment and intra-enterprise environment. A formulation of intra-enterprise scheduling economy is presented. We proved that at price equilibrium, the solution computed by the agents in the economy is a Pareto optimal. AS our first attempt, we formally formulate automated auction configuration as an optimization problem. By solving the problem adaptive negotiation in multi-agent systems can be achieved. In addition to the theoretical models, we discussed various types of auction mechanisms and their applications to agent based manufacturing scheduling. Heuristics and procedures are proposed for solving the automated auction configuration problem. To validate the analysis and proposed approaches, as a case study, we apply the automated auction configuration heuristics and the procedure to an agent based shop floor scheduling environment. Experimental results show that the auction protocol selected by the proposed heuristics provides correct system functionalities. In addition, we compared the selected mechanism with other candidate mechanisms. We found that the selected one performs better in terms of reducing communication cost and improving solution quality.
Thermoacoustic Control Modeling
Authors: Kashani Reza
Published: April 2008

Thermoacoustics can be viewed as the combination of two feedback coupling mechanisms between heat release fluctuation and the acoustics of the combustor: one resulting from the perturbations in velocity causing fluctuation in flame surface area and the other from perturbation in equivalence ratio, both causing perturbation in heat release. As in most feedback system, instability could occur when heat release perturbation is in phase with the acoustic pressure perturbation of the combustion enclosure. The emphasis of this paper is the state space formulation of the acoustics model to be used as part of the thermoacoustics model containing the first two interaction mechanisms.
A Study on Managing Cycle of Measures for Incident Based on Visualizing Problems
Authors: Otsuka Yuichi , Noguchi Hiroshi
Published: April 2008

A lot of organizations have introduced a system that collects and analyzes accident information to prevent accidents reccurence [1,2]. However, an introduced accident measures system has the following problems.
Tuned Damping of Floor Vibration
Authors: Al-hulwah Khalid , Kashani Reza , Zoghi Manoochehr
Published: April 2008

Control of floor vibration, via damping, using a three-degree-of-freedom (DOF) tuned mass damper (TMD) is explored. Three-DOF TMDs can provide as much effectiveness as traditional one degree-of-freedom TMDs while possessing less internal damping than the traditional TMDs. In this work, the use of such a system as a damping treatment for floor vibration is explored. To evaluate the effectiveness of the proposed damping-enhancement system, a scaled floor with the first resonant frequency of around 9 Hz (typical first resonant frequency of most commercial building floors) is fabricated. A 3-DOF TMD, appended to the center of the floor, is tuned to the first mode of the floor to provide damping at that mode. The comparison of the floor vibration without and with this damping treatment exhibited an average reduction of close to 10 dBs in the magnitude of the targeted mode, signifying the high damping effectiveness of the treatment.
Simulations of Rupture in Thin Films of Evaporating Liquids
Authors: Ajaev Vladimir S.
Published: April 2008

Evolution of dry patches in a thin film of a volatile liquid on a uniformly heated plate is investigated in the framework of a lubrication-type model. The effects of surface tension, evaporation, thermocapillarity, and disjoining pressure are taken into account. Dry areas on the plate are modeled by isothermal microscopic films, which are in thermodynamic equilibrium with the vapor. For non-polar liquids such equilibrium is achieved due to van der Waals forces. Simulations indicate formation of a well-defined capillary ridge around a growing dry patch and show increase in the contact line speed with time. For polar liquids the microscopic film is formed by combined action of van der Waals and electrical double layer forces, the capillary ridge is very small and the contact line speed quickly approaches a constant value. Numerical simulations demonstrate that the proposed model is capable of describing a number of complicated phenomena observed in dewetting of evaporating films.
Characterization of the Novel Coevaporated Polymer Planar Waveguide Devices
Authors: Hwang Shug-June , Yu Hsin-Her
Published: April 2008

Aromatic polyurea waveguide were fabricated by the co-evaporation of a diamino monomer and a diisocyanate monomer on a substrate. The optimum co-evaporation process conditions of the polyurea films were evaluated by FTIR measurement. The optic properties of the polymeric guiding film were characterized by the heterodyne Mach-Zehnder interferometer and prism coupler system.
Methodological Proposal to Evaluate Industrial Logistics Through Formalization
Authors: Hatakeyama K. , Reaes P. A. , Ferreira J. C. E.
Published: April 2008

In the global world reality the success of large companies depends on a permanent logistics evaluation. But to measure the stage of logistics level, a methodology, models and references are required. The national and international performance measurement in logistics activities references was used. This was carried out in order to develop a field survey, using a methodology, model and references described in this paper. Also, survey results on the use of formalization in logistics are analyzed, i.e. how the logistics organization influences the whole structure to improve the supply chain management.
Introduction of the REUSE Method: Retrieving Knowledge From Existing Product Designs
Authors: Alizon Fabrice , Shooter Steve , Simpson Timothy
Published: April 2008

In today’s marketplace, most products must better satisfy customers’ needs in the shortest time and be competitively priced. In this context, the reuse of knowledge about the targeted product is critical for developing potential product platforms. One can facilitate the reuse of existing knowledge to achieve a desired design by establishing a method that considers the layout of modules (or components) with identified flow interfaces, volume and the fundamental functional description. The problem grows with the number of candidate modules and with information-rich descriptions. The proposed REUSE (Reuse Existing Unit for Shape and Efficiency) Method greatly facilitates this search by filtering candidates based on their similarity to desired characteristics and their performance efficiency. By reusing existing information from components and modules, this approach allows the detailed specification of cost (e.g., investment and production cost for a module) along with other desired characteristics. This method applies to the complete product realization enterprise from conception through product launch. It also enables traceability of design decisions to help capture rationale and justification. A case study involving a family of cameras illustrates the proposed method.
Model for the Heat Transmission in the Human Eye
Authors: Ridouane El Hassan , Campo Antonio
Published: April 2008

Currently, most refractive surgery on the cornea is done by minimally invasive laser methods. Developing or improving new methods in laser medicine often is accompanied by theoretical modeling of the heat transmission in the human eye. The purpose of this study is to develop a mathematical model of the human eye based on the heat transfer equation. The intraocular temperature distribution is calculated using the finite volume method. The development of an accurate model of the human eye is difficult due to the lack of reliable biological data available on the constants and parameters that are used in the model. The different values for the parameters reported in the literature are employed in the model. The sensitivity of the temperature distribution to uncertainties in the parameters is investigated. The ambient temperature and blood flow rate lead to significant changes in the temperature in the anterior regions. In addition, remarkable effect is observed from the variation of the thermal conductivity of lens and blood temperature.
A Numerically Efficient Augmented Subspace Identification Algorithm for Instrumental Variable Approaches
Authors: Luo Dapeng , Leonessa Alexander
Published: April 2008

In this paper, a rank decreasing problem inherent to the application of a classical instrumental variable subspace identification (SIVID) approach will be discussed and an augmented identification approach will be proposed to address it. Simulations will demonstrate the validity of the proposed algorithm and its improved computational efficiency.
Structural Dynamics of an RF MEMS Switch
Authors: Sumali Hartono , Kuppers Jaron D. , Czaplewski David A. , Massad Jordan E. , Dyck Christopher W.
Published: April 2008

The radio-frequency micro-electromechanical system (RF MEMS) switch comprises a plate suspended by four double-cantilever springs. When electrostatic actuation is applied, the plate moves toward the substrate and closes the switch. This article discusses how simulation and experimental methods improve the performance of the switch by suppressing mechanical rebounds and thus electrical signal discontinuities. To accurately simulate the mechanical motion of the switch, a high-fidelity three-dimensional finite element model is created to couple the solid dynamics with the electrostatic actuation. The displacement of the switch at various points is measured using a laser Doppler velocimeter through a microscope. The operational deflection shapes agree with the model. The three-dimensional model produces the necessary information for an effective one-dimensional model. The latter model is used to calculate an actuation voltage waveform to minimize switch velocity at closure, thereby suppressing switch rebound. The waveforms can be refined experimentally to compensate for switch property variations. Laboratory tests indicate that the waveform suppresses or eliminates rebound events.
Analytical and Experimental Studies of Orthotropic Corner-Supported Plates With Segmented In-Plane Actuators
Authors: Sumali Hartono , Massad Jordan E. , Reu Philip L. , Chaplya Pavel M. , Martin Jeffrey W.
Published: April 2008

This paper outlines a model for a corner-supported, thin, rectangular bimorph actuated by a two-dimensional array of segmented, orthotropic PVDF laminates; it investigates the realization and measurement of such a bimorph. First, a model is derived to determine the deflected shape of an orthotropic laminate for a given distribution of voltages over the actuator array. Then, boundary conditions are realized in a laboratory setup to approach the theoretical corner-supported boundary condition. Finally, deflection measurements of actuated orthotropic PVDF laminates are performed with Electronic Speckle Pattern Interferometry and are compared to the model results.
Monotonicity and Active Set Strategies in Probabilistic Design Optimization
Authors: Chan Kuei-Yuan , Skerlos Steven J. , Papalambros Panos Y.
Published: April 2008

Probabilistic design optimization addresses the presence of uncertainty in design problems. Extensive studies on Reliability-Based Design Optimization (RBDO), i.e., problems with random variables and probabilistic constraints, have focused on improving computational efficiency of estimating values for the probabilistic functions. In the presence of many probabilistic inequality constraints, computational costs can be reduced if probabilistic values are computed only for constraints that are known to be active or likely active. This article presents an extension of monotonicity analysis concepts from deterministic problems to probabilistic ones, based on the fact that several probability metrics are monotonic transformations. These concepts can be used to construct active set strategies that reduce the computational cost associated with handling inequality constraints, similarly to the deterministic case. Such a strategy is presented as part of a sequential linear programming algorithm along with a numerical example.