bluuebunny/crossref_metadata_2025 huggingface dataset:
An Intelligent Foot Monitoring System for Diabetic Patients to Prevent Foot Ulcerations
Authors: Chitikeshi Vyshali , Mahajan Ajay , Chitikeshi Sanjeevi , Gupta Ravinder , Schoen Marco
Published: April 2008

Elevated plantar pressure plays a major role in foot problems in diabetic patients. High pressures interrupt arterial blood flow, which is further compounded by the fact that diabetic patients lose sensory feedback from their feet, hence are not able to change their stance leading to unnatural pressure points. This can lead to dermal ulcerations, necrosis, and ultimately to partial or total amputation of the foot. This paper presents a preliminary design of an intelligent shoe-insert that automatically monitors critical foot parameters in diabetic patients. The objective is to collect information on plantar pressure, temperature and moisture and come up with a system that would help in the prevention of foot ulcerations. This would be accomplished by keeping track of these parameters and sounding alarms when critical thresholds may be reached. This paper describes a comprehensive monitoring system with sensing, A/D, data storage, interpretation, transmission and alarm sounding capabilities in a single unit.
A Higher Resolution, Local Thermal Analysis of an AC Armature Winding of a High Temperature Superconductor Motor
Authors: Morega A. M. , Ordonez J. C.
Published: April 2008

The armature of high performance synchronous motors with High Temperature Superconductor (HTS) field is an AC copper winding, mounted in an iron-less stator – a so-called "air winding". Its thermal design poses difficult problems because while the armature works at ambient temperatures it is siege of higher than usual power dissipation by Joule and variable magnetic field effects. Considering that air windings are not common in classical electrical machines design, novel cooling solutions need to be considered. The standard, design class lumped thermal circuit analysis may not suffice, and it has to be complemented with a finer resolution investigation of the regions with increased structural and heat transfer complexity. As a detailed, field analysis of the entire armature is not practical a local analysis is both desirable and feasible. This paper reports a mathematical model for the heat flow in a critical part of the air-winding armature of a forced convection air-cooled HTS motor. The heat transfer mechanisms and paths, the thermal load structure unveiled by numerical simulation are then used to produce a high resolution lumped thermal circuit that conveniently complements the design class schemes used for sizing models and prototypes.
An Assessment of Myers-Briggs Temperament Indicator Based Team Formation Strategies for One-Semester Design Projects
Authors: Bannerot Richard
Published: April 2008

There has been some discussion in the literature concerning whether homogeneous or heterogeneous design teams produce the better results. This study compares the performances of three aspects of the design process as produced by 81 student teams. The teams are categorized by the Myers-Briggs Type Indicators of their members. The more personality homogeneous teams produced the better quality work. Hence, the study has added some support to the argument that homogeneous teams may be preferable, at least for relatively short projects. However, there are many factors besides similar of personalities, such as past academic performance, age, gender mix, ethnic mix, and work experience, that may affect team performance. Therefore it would be a mistake to assume that forming teams based on personality type alone will significantly and uniformly affect their performances.
Characteristics of an Evaporating Thin Film in a Microchannel
Authors: Wang Hao , Garimella Suresh V. , Murthy Jayathi Y.
Published: April 2008

The thin-film region of an evaporating meniscus is investigated through an augmented Young-Laplace model and the kinetic theory-based expression for mass transport across a liquid-vapor interface. A fourth-order differential equation for the thickness profile is developed and the boundary conditions at the beginning of the thin-film region are discussed in detail. A perturbation on the initial thickness is employed to avoid the evaporation being totally suppressed all along the meniscus. The role of capillary pressure in controlling the meniscus profile and rate of liquid supply is detailed. The evaporation heat transfer coefficient is greatly suppressed at the beginning of the thin-film region due to disjoining pressure; in the intrinsic meniscus, evaporation is suppressed due to capillary pressure, especially for low wall superheat. The importance of the thin-film region in determining the overall heat transfer is shown to depend on the channel size and degree of superheat.
Stream-of-Variation (SOVA) Modeling II: A Generic 3D Variation Model for Rigid Body Assembly in Multi Station Assembly Processes
Authors: Huang Wenzhen , Lin Jijun , Kong Zhenyu , Ceglarek Dariusz
Published: April 2008

A 3D rigid assembly modeling technique is developed for stream of variation analysis (SOVA) in multi-station processes. An assembly process is modeled as a spatial indexed state transition dynamic system. The model takes into account product and process factors such as: part-to-fixture, part-to-part and inter-station interactions, which represent the influences coming from both tooling errors and part errors. The incorporation of the virtual fixture concept [14] and inter-station interaction leads to the generic, unified SOVA model formulation. An automatic model generation technique is also developed for surmounting difficulties in modeling based on first principles. It enhances the applicability in modeling complex assemblies. The developed SOVA methodology outperforms the current simulation based techniques in computation efficiency, not only in forward analysis of complex assembly systems (tolerance analysis, sensitivity analysis), but it is also more powerful in backward analysis (tolerance synthesis and dimensional fault diagnosis). The model is validated using industrial case studies and series of simulations conducted using standardized industrial software (3DCS).
A Microfabricated Multilayer Impedance System for Ionic Transport Characterization in Nanocapillary Arrays
Authors: Prakash Shaurya , Yeom Junghoon , Shannon Mark A.
Published: April 2008

A multilayer micro-electrochemical impedance spectroscopic (μ-EIS) system with an integrated Ag/AgCI reference electrode has been developed using MEMS technologies. This μ-EIS system is used to characterize ionic and fluidic transport across nanocapillary array membranes (NCAM), which are comprised of arrays of individual nanopores. Impedance measurements giving magnitude, phase, and I-V characteristics provide insight into the interaction between translocating ions and the electric double layer (EDL) within nanocapillaries due to changes in the surface zeta potential and the ionic charge of the electrolyte. μ-EIS measurements for ionic flow through the NCAM with pore diameters from 10 to 800 nm with an aqueous salt solution indicate that these NCAM behave as nearly ideal RC circuits at electrolyte concentrations on the order of 100 mM, when the EDL within these pores do not overlap. Nyquist plots show an increase in the RC time constant with decreasing salt concentration. Under conditions of EDL overlap, hindered transport in the pores causes deviation from ideal RC circuit-like behaviour with the capacitive component of impedance beginning to dominate.
Development of a Virtual 7-Post Test Rig for Experimental Validation
Authors: Chan B. J. , Sandu Corina
Published: April 2008

A seven-post test rig is an experimental device that allows the simulation/recreation of driving conditions (e.g., racing track conditions) in the controlled environment of the laboratory. In general, the vehicle models used for tuning the real vehicle are very simplified. This may lead to differences between the results obtained using the computer model and the actual vehicle behavior as measured when mounted on the seven post test rig. This paper presents an effort to create a virtual seven post model to analyze the difference between the actual laboratory tests and the virtual model with the simplified vehicle models. A simplified full-car model is mounted on the virtual seven post rig with the ideal road input and the ideal parameters. Data from the simulation is meant to be compared with the actual experimental data from the rig to provide insight into tuning the suspension of the vehicle to optimize the tire force generation and vehicle handling. Moreover, a virtual seven post rig will allow researchers to run simulations of tuned vehicles or develop control policies for suspension system prior to performing the tests on the actual rig. The virtual rig will actually save development time and eliminate dangerous scenarios, and reduce the possibility of damaging the rig.
Friction Induced Brake Vibrations at Low Speeds: Experiments, State-Space Reconstruction and Implications on Modeling
Authors: Hetzler Hartmut , Seemann Wolfgang
Published: April 2008

Today, low frequency disc-brake noises are commonly explained as self-sustained stick-slip oscillations. Although, at a first glance this explanation seems reasonable, there are indices that cast doubt on it. For instance, the basic frequency of the observed oscillations does not scale with the disc-speed as it is with stick-slip oscillations and the classical model does not explain the observed ending of the vibrations beyond a certain speed. Indeed, our experimental studies on groaning noises reveal two different vibration patterns: stick-slip vibrations at almost vanishing relative speed and a second, differing vibration pattern at low to moderate relative speeds. Yet, these two patterns produce a very similar acoustic impression. While the experiment provides a vast amount of data, the dimension and structure of the underlying oscillation is not known a priori – hence, constructing phenomenological minimal models usually must rely on assumptions, e.g. about the number of DOF, etc. Due to noise and complexity, the measured raw data did only allow for a first straight forward insight, rendering further analysis necessary. Hence, time-delay embedding methods together with a principle component analysis were used to reconstruct a pseudo-phase space together with the embedded attractor to analyse for the system's dimension and to separate signal from noise.
On-Board Road Condition Monitoring System Using Slip-Based Tire-Road Friction Estimation and Wheel Speed Signal Analysis
Authors: Li Kang , Misener James A. , Hedrick Karl
Published: April 2008

This paper presents an on-board road condition monitoring system developed for the safety application in Vehicle Infrastructure Integration (VII) project. The system equipped on the so-called probe vehicle is able to continuously evaluate road surface in terms of slipperiness and coarseness. Road surface is classified into four grades using stock mobile sensors and GPS speed-based measurements. The task of distinguishing slippery extents of road surfaces was treated as a "pattern-recognition" problem based on experimental results such that road surfaces can be classified into three slip levels, normal (μmax ≥0.5), slippery (0.3≥μmax <0.5), and very slippery (μmax <0.3) provided enough excitation. To distinguish rough road surfaces like gravel roads from normal asphalt roads, a separate classifier making use of a filterbank for analyzing wheel speed signal was implemented. Experimental results demonstrate the feasibility of this road condition monitoring system for detecting slippery and rough road surfaces in close to real-time. Once a slippery road condition is detected by the probe vehicle, a warning message with accurate GPS position can be transmitted from the probe vehicle to road side equipment (RSE) and further be relayed to following vehicles as well as traffic management center (TMC) via Dedicated Short Range Communication (DSRC); hence the safety of road users can be improved with the aid of this cooperative or VII active safety system.
Experimental Validation for Control-Oriented Modeling of Multi-Cylinder HCCI Diesel Engines
Authors: Canova Marcello , Midlam-Mohler Shawn , Guezennec Yann , Rizzoni Giorgio , Garzarella Luca , Ghisolfi Marco , Chiara Fabio
Published: April 2008

Homogeneous Charge Compression Ignition (HCCI) is a combustion process based on a lean, homogeneous, premixed charge reacting and burning uniformly throughout the mixture volume. This principle leads to a consistent decrease in NOx and PM emissions, while the combustion efficiency remains comparable to traditional Compression Ignition Direct Injection (CIDI) engines at low and mid-load operations. However, understanding and controlling the combustion process is still extremely difficult, as well as finding a proper method for the fuel introduction. A viable method consists of premixing the charge by applying a proper fuel atomization device in the intake port, thus decoupling the HCCI mixture formation from the traditional in-cylinder injection. This avoids the traditional drawbacks associated to external Diesel mixture preparation, such as high intake heating, low compression ratio, wall wetting, and soot formation. The system, previously developed and tested on a single-cylinder engine, has been successfully applied to multi-cylinder Diesel engine for automotive applications. Building on previous modeling and experimental work, the paper reports a detailed experimental analysis of HCCI combustion with external mixture formation. In the considered testing setup, the fuel atomizer has been applied to a four-cylinder turbo-charged Common Rail Diesel engine equipped with a cooled EGR system. In order to extend the knowledge on the process and to provide a large base of data for the identification of Control-Oriented Models, Diesel-fueled HCCI combustion has been characterized over different values of loads, EGR dilution and boost pressures. The data collected were then used for the validation of a HCCI Diesel engine model that was previously built for steady state and transient simulation and for control purposes. The experimental results obtained, especially considering the emission levels and efficiency, suggest that the technology developed for external mixture formation is a feasible upgrade for automotive Diesel engines without introducing additional design efforts or constraints on the DI combustion and injection system.
Analysis of Heat Generation Through-Electromagnetic Energy Conversion for Magnetic Hyperthermia Cancer Treatment
Authors: Hayek Saleh S. , Chen Ching-Jen , Haik Yousef S. , Weatherspoon Mark H.
Published: April 2008

Hyperthermia (HT) is a cancer treatment that utilizes a variety of heating methods to destroy cancerous tumors. A diversity of technical problems still exists regarding HT's different approaches, therapeutic potential, and evidence of effectiveness. The foremost problem is in generating and controlling heat in tumors to target cancer sites. The window of temperature for HT is between 42°C and 45°C, with the literature suggesting 43°C to be the ideal temperature for inducing apoptosis (programmed cell death). Normal cells undergo necrosis at higher temperatures than that of the specified range. To address control problems, various methods have been utilized to localize HT heating and limit its temperatures through various applicators, materials, and procedures. One method has been to implant various materials into the human body to heat tumors, a process known as Magnetic Hyperthermia (MH) as it uses magnetic nanoparticles (NP). This method is particularly useful for sending thermal energy to deep seated tumors by using ferro/ferri magnetic NP that absorb non-ionizing electromagnetic (EM) fields delivered into the human body externally. These NP have been shown to heat surrounding tissue until they reach a Curie temperature (Tc) at which generated heat is minimized (many thermodynamic properties change at Tc, such as dielectric, elastic, optical and thermal properties. Fabricated NP, due to spontaneous polarization, can heat via hysteresis losses under applied EM fields making them candidates for testing in (EM) HT systems. Various ferro- and ferromagnetic materials have been studied extensively by this group (e.g.: Ni-Cu, Ni-Co, Ni-Cr, Er, Ce, Gd, and their alloys, etc.) as candidates for HT due to their production of heat through hysteresis or magnetic spin mechanisms. With the use of these nanoparticle systems, the focus of this paper is to produce analysis of heat generation through electromagnetic energy conversion for magnetic hyperthermia cancer treatment and to investigate the heat transfer and heat generation of magnetic NP due to temperature rise upon application of externally applied AC magnetic field. Both, polarization switching and inhomogenities affect polarization orientation within a crystal. Domain switching occurs in two steps: first, the domain nucleates at critical level of applied EM field; second, the interface between the two domains propagates. Particles moving across the interface transform from one domain type to another, which leads to a release of energy in the form of heat. This, in turn, leads to a temperature rise at the interface.
Modeling Lattice Dynamics and Heat Capacities of Zeolites
Authors: Greenstein Abraham , Hudiono Yeny , Nair Sankar , Graham Samuel
Published: April 2008

A theoretical study of the heat capacities of Quartz, zeolite MTT, and zeolite MFI is presented. The technique used to calculate the heat capacity can be applied to a many dielectrics, even those that are highly anisotropic, with complex crystal structures. For the aforementioned materials the assumptions used in Debye theory are too restrictive, the methodology presented in this paper uses a full set of dispersion relations obtained from atomistic simulation. Agreement with experiment for all materials studied is excellent, with the exceptions of temperature regions where phase transitions occur. The methodology that is used was developed with thermal conductivity in mind. It is hoped that this model will be smoothly incorporated into future conductivity models. Additionally, the effect of Al substitution on the heat capacity of MFI is investigated. It is predicted that aluminum substitution has a miniscule effect on the heat capacity of MFI.
Analysis of Natural Convection Coupled With Thermal Radiation in Novel High-Concentration Nonimaging-Optics-Based System for Multi-Junction Solar Cells
Authors: Diaz Gerardo C. , Winston Roland , Ritschel Alexander , Pineda Sergio , Benitez Pablo
Published: April 2008

The design of solar concentrators based on nonimaging optics provides an inexpensive, but highly powerful concentrating system with large angular tolerance and uniform cell illumination. However, multi-junction tandem-cell-based concentrators require high levels of concentration to become cost effective. The two-mirror design is capable of working at an average concentration over 800 suns with local concentrations below 2000 suns without a homogenizing kaleidoscope. With this level of concentration it is essential to analyze the thermal effects of the unit at different operating conditions. In this paper we analyze the coupled effects of natural convection and surface thermal radiation inside the air-filled enclosure formed by the primary mirror and the cover of the concentrator that holds the secondary mirror. A coordinate transformation is applied to the governing equations to generate a mapping from a parabolic domain to a rectangular domain. The results show an increase in the total Nusselt number with a decrease in the maximum temperature of the secondary mirror.
Analytical Redundancy Based Fault Tolerant Control of a Steer-by-Wire System
Authors: Anwar Sohel , Chen Lei
Published: April 2008

This paper presents a novel observer-based analytical redundancy for a steer-by-wire (SBW) system. In order to achieve high level of reliability for a By-Wire system, double, triple, or even quadruple redundant sensors, actuators, communication networks, and controllers are needed. But this added hardware increases the overall cost of the vehicle. This paper utilizes a novel analytical redundancy methodology to reduce the total number of redundant road-wheel angle (RWA) sensors in a triply redundant RWA-based SBW system, while maintaining a high level of reliability. The self-aligning torque at road-tire interface due to the steering dynamics has been modeled as a function of the linear vehicle states. A full state observer was designed using the combined model of the vehicle and SBW system to estimate the vehicle body side slip angle. The steering angle was then estimated from the observed and measured states of the vehicle (body side slip angle and yaw rate) as well as the current input to the SBW electric motor(s). With at least two physical road-wheel angle sensors and the analytical estimation of the RWA value (which replaces the third physical sensor), a fault detection and isolation (FDI) algorithm was developed using a majority voting scheme. The FDI algorithm was then used to detect faulty sensor(s) in order to maintain safe drivability. The proposed analytical redundancy based fault detection & isolation algorithms and the linearized vehicle model were modeled in SIMULINK. Simulation of the proposed algorithm was performed for both single and multiple sensor faults. Simulation results show that the proposed analytical redundancy based fault detection and isolation algorithm provides the same level of fault tolerance as in an SBW system with full hardware redundancy against single point failures.
Self-Reproducing Machines: Preventing Degeneracy
Authors: Owens Patrick D. , Ulsoy A. Galip
Published: April 2008

Machines produced by humans exhibit insufficient complexity to produce similar machines. As John von Neumann originally postulated, if biological systems are able to successfully reproduce, then there must be some characteristic that we can embed in machines to give them the ability to reproduce. Such a self-reproductive machine, also imbued with the ability to do constructive work, could prove enormously useful to the human race. This paper considers a simple self-reproducing machine, which consists of a 2-DOF, planar robot arm capable of picking up and placing the components of another arm. If the robot places the components within the allowable tolerance, then the original arm has successfully reproduced. An assembly line is constructed, so that a self-reproduction process can proceed along a track. If this process eventually fails because one robot is not capable of assembling another, then the system is said to be degenerate. Otherwise, the system is sustainable. A kinematic model that maps component placement errors from one generation of the robot arm to the next was derived. The system exhibited exponential growth in component placement errors. Thus, this self-reproduction system is degenerate. This system is then augmented to provide error-correction during the assembly process. With the application of error-correction the self-reproduction process is made sustainable. The minimal amount of error-correction required to achieve sustainable self-reproduction was investigated through sensor quantization, and it was shown that the amount of fidelity in the error-correction signal determines the success of the self-reproduction process. This self-reproduction system was also analyzed in the context of Kabamba's Generation Theory, which could predict the results obtained through simulation regarding degeneracy or sustainability.
Polymer Grippers as End-Effectors for Biological Sample Manipulation
Authors: Colinjivadi Karthik S. , Honnatti Meghana , Lee J.-B. , Draper Rockford , Ellis Matthew , Skidmore George , Hughes Gareth
Published: April 2008

We report the development of completely releasable SU-8 based polymer microgripper and the manipulation of normal rat kidney (NRK) cells suspended in phosphate buffered saline (PBS) solution using a generic biological sample manipulator, which incorporates such a polymer microgripper as an end-effector. The electrically insulative polymer gripper consists of a thick (~50 μm), patterned high aspect ratio (~5:1) layer of SU-8 as the structural layer and a thin nickel layer as the electrothermal heating layer. The fabricated polymer gripper was completely released from the substrate and mounted onto a ceramic pad. The gripper was characterized in air and PBS, and the displacement at the tips was 12 μm for 0.5 V in air and for 2 V in PBS. The mounted gripper was assembled as end-effector onto a biological nano-manipulator (L200, Zyvex Corporation, Richardson, TX). Pick-and-place of a single cell from a cluster of suspended cells in aqueous medium has been demonstrated using this set-up.
Investigation of Packaging Effect of Silicon-Based Piezoresistive Pressure Sensor
Authors: Chu Chen-Hing , Chou Tsung-Lin , Lin Chun-Te , Chiang Kuo-Ning
Published: April 2008

The silicon-based pressure sensor is one of the major applications in the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in industry and its measurement accuracy is more rigorous in many advanced applications. In order to operate the piezoresistive pressure sensor in harsh environment, the silicone get is usually used to protect the die surface and wire bond while allowing the pressure signal to be transmitted to the silicon diaphragm. The major factor affecting the high performance applications of the piezoresistive pressure sensor is the temperature dependence of its pressure characteristics. Therefore, the thermal and packaging effects caused by the silicone gel behaviors should be taken into consideration to obtain better sensor accuracy and sensitivity. For this reason, a finite element method (FEM) is adopted for the sensor performance evaluation, and the thermal and pressure loading is applied on the sensor to study the output signal sensitivity as well as the packaging-induced signal variation, thermal/packaging effect reduction, and output signal prediction for the pressure sensors. The design parameters include silicon die size, silicone gel geometry and its material properties. The simulation results show that the smaller die size and the thicker die thickness can reduce the packaging-induced thermal effect. Furthermore, the different geometry of silicone gel also influences the sensitivity of pressure sensor.
Experimental Investigation of Pulsed Laser Deposition Based on a Compressible Flow Framework
Authors: Sheng Biqing , Zhang Zhaoyan
Published: April 2008

Pulsed laser deposition (PLD) is a popular technique for creating thin films. The film characteristics are directly related to the kinetic energy of the laser-induced plume. According to the theory of transient shock wave expansion during laser ablation, laser-induced plume properties are strongly affected by laser intensity as well as ambient temperature, pressure, and gas species. This theory leads to the development of PLD strategies to properly optimize the PLD parameters. The experiments were carried out to deposit diamond-like carbon (DLC) thin films under different ambient temperature, pressure and gas species. The deposited DLC thin films were characterized by Raman spectroscopy. Experimental results showed that the thin film quality can be improved by decreasing the ambient temperature, increasing the ambient pressure and using ambient gases with low molecular weight. Experimental results agree well with the theoretical prediction.
Finite Element Simulation of Plane Magnetic Abrasive Finishing
Authors: Khatri Atul , Yadava Vinod
Published: April 2008

The final machining (or finishing) of precision parts with high accuracy level is making the application of abrasive finishing technologies increasingly important. Magnetic abrasive finishing (MAF) is a new advanced finishing process used for fine finishing of extremely hard materials. It is employed for finishing of metals and non-metals. This paper focuses on the modeling and simulation for the prediction of surface roughness in plane magnetic abrasive finishing. A finite element based model is developed to find the magnetic potential distribution in gap between tool and workpiece. Further, magnetic potential is used to evaluate machining pressure, material removal and finally surface roughness of the workpiece surface. The simulation results are confirmed compared with the experimental results available in the literature. The simulated workpiece surface roughness shows features which are similar in nature to the experimental results.
Numerical Simulation of Submerged Flows With Baffles Using v2-f- and k-e Turbulence Models
Authors: Mehdizadeh A. , Firoozabadi B. , Sherif S. A.
Published: April 2008

This paper introduces the concept of a submerged hydraulic jump being used for energy dissipation. A baffle wall is used to produce a stable deflected surface jet, thereby deflecting the high-velocity supercritical stream away from the bed to the surface. An elliptic relaxation turbulence model ([Equation] - f model) has been used to simulate this submerged flow. During the last few years, the [Equation] - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proved that the [Equation] - f model is superior to other RANS methods in many fluid flows where complex flow features are present. In this study, we compared the results of both models with each other and with available experimental data. In addition, based on a series of numerical simulations, a diagram was developed that predicts the effect of baffle position on the friction coefficient over the bed. This feature should help preventing or reducing erosion over the bed. Moreover, we have shown that in numerical simulation, like experimental data, in some cases the flow regimes of submerged flow with baffles can either be a deflected surface jet or reattached wall jet.
Architecture Design for Automatic Step-NC Code Generation Within Distributed Integrated Manufacturing Environment
Authors: Mohamed Khaled A.
Published: April 2008

Most of the companies still use the old or traditional practice for generating the NC code for machining as opposed to automated NC code generation, because they either lack the CAD/CAM technology or suffer from a gap between CAD/CAM (or CAM) and CNC machining. That leads to a missing link between the design department and the manufacturing department (or shop floor). The primary objective of this work is to create an integrated manufacturing environment in which a part would be designed using a standard available CAD system. The design is saved in a CAD file has standard format (STEP, ISO 10303). Feature extraction system is developed and used to extract out machining or manufacturing features. Artificial Intelligence (AI) and knowledge-based systems are developed based on 'Agent Technology'. The agents are programmed to accomplish various activities such as selecting machine types, cutting tools and cutting parameters to machine specific geometries or features. Then, feature data is saved in a in a STEP-NC (ISO14649) file, which can be transmitted between various locations and CAX systems. They are used for information retrieval, data exchange, and decision-making support. So, product data and information is available to shop floor and machine tool in addition to CAD/CAM systems.
A Local Steady State Approach for Fault Diagnosis of Continuous Production Systems
Authors: Schrems Andrea , Efendic Hajrudin , del Re Luigi
Published: April 2008

Data based models are frequently and successfully used to monitor the operation state and detect faults in industrial plants. Deriving these models from data, however, can be quite difficult and unreliable, especially if data from actual operation have to be used, as the resulting optimization problem often becomes ill conditioned: available data may not contain sufficient information, in particular for continuous production systems which are often run for longer times under almost constant operating conditions. This paper presents a local steady state approach for such problems based on complexity reduction: data are pre-processed prior to the modeling phase to allow the build-up of reduced complexity models, thus replacing the original ill conditioned problem with a better conditioned one. A method is presented to extract the relevant information about the process from measurement data in such a way to guarantee that the resulting simplified models will retain the essential characteristics of the original system required to perform fault diagnosis successfully. This approach has been used in different industrial applications and has proved reliable and efficient.
Stabilization of the Rotary Inverted Pendulum Using Aggregate Modeling
Authors: Kiriakidis Kiriakos , Feemster Matthew , O'Brien Richard
Published: April 2008

Using the method of aggregate modeling, the paper derives an approximation of the rotary pendulum's Euler-Lagrange dynamics within a specified operating region. Based on the resulting aggregate model, the authors cast the system's stabilization as a feasibility problem associated with linear matrix inequalities. Furthermore, the authors test the resulting stabilizing controller on the actual rotary pendulum and verify the expected results experimentally.
Analytical Modeling of On-Chip Hotspot Cooling Using Silicon Thermoelectric Microcoolers
Authors: Wang Peng , Bar-Cohen Avram , Yang Bao
Published: April 2008

Thermal management of microprocessors has become an increasing challenge in recent years because of localized high flux hotspots which can not be effectively removed by conventional cooling techniques. This paper describes the novel use of the silicon chip itself as thermoelectric microcooler to suppress the hotspot temperature. A three-dimensional analytical thermal model of the silicon chip, including localized silicon thermoelectric cooling, thermoelectric heating, Joule heating, hotspot heating, background heating, and conductive/convective cooling on the back of the silicon chip, is developed and used to predict the on-chip hotspot cooling performance. The effects of chip thickness, microcooler size, doping concentration and parasitic Joule heating from the electric contact resistance on hotspot cooling are investigated in details.
Reference-Free Transducer Self-Diagnosis Scheme Development
Authors: Lee Sang Jun , Sohn Hoon
Published: April 2008

A self-sensing scheme, which allows using Lead Zirconate Titanate (PZT) materials for simultaneous sensing and actuation, has been developed in the context of structural health monitoring (SHM). Based on the self-sensing scheme developed, a time response of the PZT transducer coupled with a mechanical response of the host structure is successfully extracted while the same PZT transducer is excited by a specific input signal. Then, the measured PZT response is used for detecting transducer defects such as PZT cracking and debonding. In order to improve the reliability of transducer diagnosis, the reference-free transducer self-diagnosis scheme based on the developed self-sensing scheme is proposed. Finally, the effectiveness of the proposed self-diagnosis scheme is examined using PZT wafers instrumented on a fixed-free aluminum beam.
Input Shaping for Nonlinear Drive Systems
Authors: Bradley Thomas H. , Hall Terry , Xie Qiulin , Singhose William , Lawrence Jason W.
Published: April 2008

Input shaping is effective at eliminating vibration in many types of flexible systems. This paper discusses how input shaping is affected by actuators with unequal acceleration and deceleration dynamics. It is shown that traditional Unity Magnitude Zero Vibration (UMZV) shapers have degraded performance when used with such actuators. A new type of UMZV shaped input command is developed to compensate for the nonlinearity. Experiments on a portable bridge crane demonstrate the effectiveness of the proposed approach.
Buckling Stability of Adhesively Bonded Composite Conical Shells Under Both Axial Compressive and External Pressure Loads
Authors: Yavuz A. Kadir , Phoenix S. Leigh
Published: April 2008

A mathematical model is developed for buckling stability of an adhesively bonded composite conical shell system consisting of carbon fiber in a polyimide (PI) matrix. The conical shell is modeled by two orthotropic layers bonded together with a PI adhesive. In-plane compressive and external surface pressure loads are applied. The adhesive layer is modeled by mechanical linear normal and shear springs. The Galerkin method is applied to analyze the buckling stability of the structure as an eigenvalue problem to give critical buckling loads and corresponding mode shapes. Parametric studies are performed to show effects of system parameters on buckling stability of the system.
Tunable Piezoelectric Cantilever Beams for Energy Harvesting
Authors: Charnegie David , Mo Changki , Frederick Amanda A. , Clark William W.
Published: April 2008

Over the past several years, there has been increasing interest in harvesting energy from ambient vibrations in the environment by converting mechanical energy into electrical energy. A popular method is to use a piezoelectric cantilever beam. In order to harvest the most energy with the device, the beam's fundamental mode must be excited. However, this is not always possible due to manufacturing of the device or fluctuations in the vibration source. By being able to change the frequencies of the beam, the device can be more effective in harvesting energy. In this paper, a model for a three layered piezoelectric cantilever beam utilizing a shunt tuning circuit will be presented. The fundamental frequency of a cantilever beam is dependent on the stiffness and mass of the beam. Either adding a tip mass to the end of the beam or increasing the dimensions of the beam can alter the mass. The stiffness of the beam is a function of the geometry, mechanical properties, and the electromechanical coupling of the piezoelectric element. In this paper we prepare the use of a piezoelectric layer with an attached shunt circuit for tuning its stiffness, and thus the beam frequency. The piezoelectric coefficients of this layer and its shunt circuit determine the amount of electromechanical coupling. By varying the shunt circuit, the beam can be tuned to a certain frequency. This paper presents a study of the effects additional harvesting and tuning layers have on the amount of tuning and generated power in the beam. These additional layers will add more piezoelectric material as well as mass to the beam and therefore there will be a balance between the amount of harvested energy and the tunable frequency range. By quantifying the effects of these parameters, it will be easier to design a harvester to be used in a particular frequency range as well as to produce a certain level of power.
Analysis of Segregation Phenomenon in Granular Motion
Authors: Fang X. , Tang J.
Published: April 2008

Over the past decade, many studies have been carried out to investigate one of the unique phenomena in granular materials: vibration-induced segregation in granular mixture, i.e., under vertical vibration, larger granules rise to the top even without density difference with other granules. However, the mechanisms behind this phenomenon are not yet completely understood. In this study, the discrete element method (DEM) is used for the numerical analysis of the granular segregation in a vertically vibrating container. We systematically investigate the rising time of an intruder inside the granular mixture as a function of the granular size, density, depth, and the vibrating frequency and amplitude. Our studies show that the segregation phenomenon is caused by a variety of mechanisms within different vibration regimes. Under weak vibration, segregation is driven by the geometrical effect and inertia. Under moderate vibration, segregation can be enhanced dramatically with the occurrence of convection. Under strong vibration where the granular material becomes fluidized, the buoyancy or sinkage of granules prevails and segregation may be suppressed.
Granular Damping Analysis Using a Direct Simulation Monte Carlo Approach
Authors: Fang X. , Tang J.
Published: April 2008

Granular damping, which possesses promising features for vibration suppression in harsh environment, has been studied using empirical analysis and more recently using the discrete element method (DEM). The mechanism of granular damping is highly nonlinear, and, when numerical analyses are performed, usually a relatively long simulation time of structural vibration is needed to reflect the damping behavior especially at low frequency range. The present research explores the granular damping analysis by means of the Direct Simulation Monte Carlo (DSMC) approach. Unlike the DEM that tracks the motion of granules using the direct numerical integration of Newton's equations, the DSMC is a statistical approach derived from the Boltzmann equation to describe the velocity evolution of the granular system. Since the exact time and locations of contacts among granules are not calculated in the DSMC, a significant reduction in computational time/cost can be achieved. While the DSMC has been exercised in a variety of granular systems, its implementation to granular damping analysis poses unique challenges. In this research, we develop a new method that enables the coupled analysis of the stochastic granular motion and the structural vibration. The complicated energy transfer and dissipation due to the collisions between the granules and the host structure and among the granules is directly and accurately incorporated into the analysis, which is essential to damping evaluation. Also, the effects of granular packing ratio and the excluded volume of granules, which may not be included in conventional DSMC method, are explicitly taken into account in the proposed approach. A series of numerical analyses are performed to highlight the accuracy and efficiency of the new approach. Using this new algorithm, we can carry out parametric analysis on granular damping to obtain guidelines for system optimization.
Design and Dynamical Analysis of a SAR Membrane Antenna Deployable Structure
Authors: Shen Yu , Montminy Steeve , Zheng Wanping
Published: April 2008

Large deployable membrane antennas for Synthetic Aperture Radar (SAR) satellites have attracted much attention for their low mass, high packaging efficiency, and low fabrication cost. An extendible support structure (ESS) could be used to deploy and support a multi-layer membrane antenna in a precise configuration once it is deployed on orbit. In this paper, an ESS for a membrane antenna with several foldable frames is designed. The ESS can be synchronously deployed by a six-bar-linkage mechanism and several closed-cable loops. A kinematical model of the deployable mechanism is developed to obtain the optimal design of the mechanism for a goal of all foldable frames locked in a same plane after they are fully deployed. A dynamic model of the ESS is developed to investigate its dynamical performance. The goal of the simulation is to compare the dynamic performances of the ESS when the frames are regarded as rigid and flexible. The simulation results are obtained with symbolic dynamic analysis software DynaFlexPro.
The Improvement of a Manufacturing Stream Using the DMAIC Method
Authors: Gentili Enzo , Aggogeri Francesco , Mazzola Marco
Published: April 2008

The need for globalization, the saturation and instability of markets, the life-cycle time reduction of products and the customer demands have been the main factors that have contributed to a radical change of management conceptions and strategies. In this context the application of improvement methodologies, which suggest techniques and methods to organize and manage the manufacturing and service of industrial processes, is essential to increase the business performance. The purpose of this paper is to show the main steps to improve the efficiency and effectiveness of the manufacturing stream of a company that produces both professional and simple kitchen knives. This company is leader in its market and it focuses on safety, reliability, design and quality of its products. The improvement project analyses all potential sources of product defects and scraps, assessing the main manufacturing processes (shearing, hardening, rolling, sharpening and pressing), and suggests every possible solution to increase the performance level. In order to achieve these goals the Lean Six Sigma methodology was applied, following the DMAIC (define, measure, analyse, improve and control) problem solving approach. The DMAIC is a better way to manage an improvement project putting the customer first and using facts and data to achieve better solutions. The project also highlights an economic analysis in order to understand the benefits and the convenience of a rigorous and structured improvement plan.
An Information Economic Approach for Model Selection In Engineering Design
Authors: Ling Jay , Paredis Christiaan J. J.
Published: April 2008

An important element of successful engineering design is the effective management of resources to support design decisions. Design decisions can be thought of as having two phases—a formulation phase and a solution phase. As part of the formulation phase, engineers must decide which models to use in support of design decisions. Although more accurate models typically lead to better decisions, they also cost more. The question therefore is: Which model provides the best cost-benefit trade-off? In this paper, we focus in particular on the situation in which the systematic error in the models can be bounded by an interval. Based on principles of information economics, the interval-based model error results in bounds on the expected economic value of using a particular model in support of a certain design decision. The decision maker can then select the model that provides the best overall value, considering both the expected benefits resulting from the decision and the cost of the decision-making process. The approach is illustrated with the design of an I-beam structure.
Cooperative Collision Detection Based on Future-Trajectory Prediction
Authors: Huang Jihua , Tan Han-Shue
Published: April 2008

Collision Warning Systems (CWSs) are becoming an important part of vehicle active safety. Commercial CWSs using information measured by the subject vehicle have been available on trucks, buses and passenger cars. Another emerging trend in the development of CWS is based on the cooperative driving concept, where vehicles are equipped with absolute-positioning systems and inter-vehicle communications. The absolute positions, together with the rich information from vehicle motion sensors, facilitate the prediction of vehicle future trajectories. With the current positions and the predicted trajectories of the surrounding vehicles, each vehicle in principle can establish a comprehensive understanding and anticipation of its driving environment. To leverage these potential advantages of the cooperative driving concept, this paper proposes, designs and experiments a collision warning system based on vehicle future-trajectory prediction. A systematic approach with probability measures is designed to detect potential trajectory conflict between the predicted trajectories. Collision detection is then based on the potential trajectory conflicts with examination of their persistency and urgency. Experimental results are provided to verify the feasibility of the design.