bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuzzy Control of Spindle Torque in High-Speed Milling Processes
Authors: Haber Rodolfo , Liang Steven Y. , Alique Jose´ R. , Alique Angel , Ros Salvador
Published: April 2008

Torque control through feed rate and spindle speed manipulation can produce significant economic benefits for machining processes by reducing the cycle time. This paper focuses on the design and implementation of a fuzzy-logic-based torque control system, embedded in an open architecture computer numerical control (CNC), in order to provide an optimization function for the material removal rate. The control system adjusts the feed rate and spindle speed simultaneously as needed, to regulate the cutting torque using the CNC’s own resources without requiring additional hardware overhead. The control system consists of a two inputs (i.e., torque error and change of error) -two outputs (i.e., the feed rate and spindle speed increment) fuzzy controller, which are embedded within the kernel of a standard open control. Two approaches are tested and their performance is assessed using several performance measurements. These approaches are the two inputs-two outputs for the fuzzy controller and a single-output fuzzy controller (i.e., only feed rate modification). The results demonstrate that the proposed control strategy provides better accuracy, and machining cycle time than the others, thus increasing the metal removal rate.
The Characteristic Curve Method in Energy Systems Diagnosis: Analysis of Uncertainties in a Real Plant
Authors: Lazzaretto Andrea , Toffolo Andrea , Passuello Riccardo , Ju¨des Marc , Cziesla Frank , Tsatsaronis George
Published: April 2008

Thermoeconomic diagnostic approaches have proved to be effective in quantifying additional exergy consumption and costs, whereas they demonstrated to be less appropriate in the search of malfunction causes. With the intent of overcoming this limitation the Characteristic Curve Method was suggested by Toffolo and Lazzaretto, which is based on the idea that every malfunction leaves an undeletable trace in the system: the modification of the component characteristic curve. An exergetic index was found to be very suitable to highlight this trace, and demonstrated consequently to be very effective in identifying the causes of malfunctions. In this paper the method is applied to an existing cogeneration plant, that is simulated using a commercially available code. Simulation errors due to the iterative criterion used by the simulator to find convergence are considered in the analysis, and the reliability of the method under these conditions checked. The example of application is used to show all the calculation steps to be performed, and the way of reading the results in order to properly detect causes of malfunctions. This helps avoid misleading conclusions and demonstrates the practical and easy application of the method when commercial simulator codes are used.
MMM Stress Evaluation and Fracture Analysis for Steam Turbine Failure Blade
Authors: Xing Hai-Yan , Yu Min Qiang , Li Xue Feng
Published: April 2008

Metal magnetic memory (MMM) technology, a new NDE method, has been applied to stress evaluation and fracture analysis for the 50MW turbine failure blade. The static and dynamic stress of failure blade is calculated and analyzed. The rupture blade of steam turbine is detected at workshop. Given are the MMM signal characteristics of stress distribution for the failure blade and fracture face. It has been found: for the blade profile, the MMM air-out side curve occurs more zero passage signals than air-in side one; for the fracture surface, the crack transition zone’s MMM variation amplitude is minimal, the crack initiation zone’s is in the middle, and the tear fracture zone’s is maximal. The result from small hole stress measuring method is consistent with MMM result. This shows MMM technology is a new tool of fracture analysis and stress testing in engineering practice.
Implementation of GapSpace Analysis
Authors: Morse Edward P. , You Xiaobin
Published: April 2008

Tolerance analysis of mechanical assemblies requires the identification of locations of potential part interference, and determining whether the allowable geometric variation permitted by the part tolerances will cause part interference. Current commercial assembly modelers (and much of the classic work in assembly research [1-3]) require that the degrees of freedom between parts in an assembly be fully constrained prior to analysis. This method relies on the kinematics of the assembly contacts to determine whether the parts will assembly without interference. Our method — GapSpace — does not require these constraints in determining if interference-free assembly is possible [4]. Less restrictive, and thus less costly, tolerances can be used in assemblies where the specific relationships between surfaces is not predetermined. One difficulty we’ve had in implementing this GapSpace method is overcoming the constraints imposed by commercial modeling systems [5]. In this paper we report our success in implementing the GapSpace techniques in one such modeling system. Included in this system are additional user menus and interfaces which allow the identification of “fitting conditions” and analysis of the tolerances placed on the assembly components.
Effect of Flow Fields on Morphology of PP/Nano/CaCO3 Composite and Its Rheological Behavior
Authors: Huang Han-Xiong , Jiang Guo , Mao Shan-Qiang
Published: April 2008

Polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was prepared using a co-rotating, intermeshing twin-screw extruder. The effect of flow fields on the morphology of the nanocomposite was investigated. Transmission electron microscopy (TEM) was used for the determination of the morphology in the nanocomposite. The crystallization behavior of the nanocomposite was studied by using differential scanning calorimetry (DSC) and the melt shear viscosity was investigated by a melt flow index tester. The study showed that the flow field, through appropriately combining the type of the screw elements in this work, plays an important role in developing morphology of the nanocomposite. In addition, it was shown that the melt viscosity for the nanocomposite at the filler content less than 10 wt% is lower than that of neat PP.
Computational Analysis of Flow Inside a Diffuser of Three-Dimensional Supersonic Non-Steady Ejectors
Authors: Alhussan Khaled , Garris Charles
Published: April 2008

The work to be presented herein is a Computational Fluid Dynamics investigation of the complex fluid mechanisms that occur inside a non-steady, three-dimensional, supersonic pressure exchange ejector, specifically with regard to the pressure exchange mechanisms and the induction processes between a “driving” primary fluid and a “driven” secondary fluid and how this is affected by the diffuser surface. The results will show that this ejector is capable of producing the desire affect of the flow induction in a three-dimensional supersonic, non-steady, viscous flow. Results of contour plots of total pressure and static pressure demonstrate that the flow inside the diffuser is a critical element in flow induction mechanism, especially when a pressure recovery is needed. Results of velocity vectors will show the structure of flow induction mechanism in a complex three-dimensional conical surface.
Effect of Surfactant Additives on a Boundary Layer on a Flat Plate
Authors: Ogata Satoshi , Fujita Takeshi
Published: April 2008

The effect of surfactant solutions on the boundary layer over a flat plate has been investigated in the Reynolds number range of approximately Re < 153,000. Experiments were carried out by measuring the velocity profile using a PIV system. Surfactant solutions tested were aqueous solutions of oleyl-bihydroxyethyl methyl ammonium chloride (Ethoquad O/12) in the concentration range of 50 to 500 ppm, to which sodium salicylate was added as a counterion. It was clarified that the boundary layer thickness of surfactant solutions increases significantly near the leading edge comparing with that of tap water, and parallelly develops in that obtained by the Blasius equation. For lower surfactant concentration (50 and 200 ppm) the velocity profile near the wall is distributed between that of laminar flow and turbulent flow for Newtonian fluid. When the Reynolds number increases, the velocity profile gradually increases from the outer edge of the boundary, and approaches the turbulent velocity profile of Newtonian fluid. For higher surfactant concentration (500 ppm), the velocity profile shows large S-shape. The velocity profile does not change very much, even if the Reynolds increases. The shape parameter with surfactant solutions decreases slightly comparing that of tap water at Re < 92,000, The value of shape parameter H with surfactant solution shows 1.66 < H < 2.32.
Numerical Prediction of Atherosclerotic Plaque Temperature as a Function of Plaque Size and Composition
Authors: Ley Obdulia , Kim Taehong
Published: April 2008

Atherosclerotic plaque or cholesterol deposits in arteries with high likelihood of rupture experience an inflammatory cascade that produces a temperature inhomogeneity within the affected artery. As a result, a new and promising method to detect plaque vulnerability is based on the measurement of the arterial wall temperature (AWT). In this paper, the energy equation is solved to determine the plaque temperature distribution on the vessel wall considering blood flow, inflammatory cell density, and plaque size. Two different blood vessel shapes are considered: a stenotic straight artery, and an arterial bend, both with geometry and dimensions that correspond to the human aorta and a human coronary artery, respectively. These vessels were selected because atherosclerotic plaques are commonly encountered in such arteries. The plaque is located in the sites of low shear stress and variations in its volume and cell density are considered. The heat generation in the vulnerable plaque due to macrophage activation in inflammatory processes is taken from the literature. This paper presents steady state calculations. Reynolds numbers of 300 and 500 are used to represent maximum and minimum velocities during the cardiac cycle. Plots of plaque and arterial wall temperature as a function of macrophage concentration, and activation stage are presented; and the maximum plaque temperature is compared with arterial wall temperature values found in the literature.
Self-Organized Multilayers via a Dipole Interaction Mechanism
Authors: Salac David , Lu Wei
Published: April 2008

A phase field model is developed to simulate the molecular motion and patterning under the combined actions of dipole moments, intermolecular forces, entropy, and external electric field. The study reveals self-alignment, pattern conformation and the possibility to reduce the domain sizes via a layer by layer approach.
A Numerical Study of Uncertainty in Stability and Surface Location Error in High-Speed Milling
Authors: Kurdi Mohammad H. , Schmitz Tony L. , Haftka Raphael T. , Mann Brian P.
Published: April 2008

High-speed milling offers an efficient tool for developing cost effective manufacturing processes with acceptable dimensional accuracy. Realization of these benefits depends on an appropriate selection of preferred operating conditions. In a previous study, optimization was used to find these conditions for two objectives: material removal rate (MRR) and surface location error (SLE), with a Pareto front or tradeoff curve found for the two competing objectives. However, confidence in the optimization results depends on the uncertainty in the input parameters to the milling model (time finite element analysis was applied here for simultaneous prediction of stability and surface location error). In this paper the uncertainty of these input parameters such as cutting force coefficients, tool modal parameters, and cutting parameters is evaluated. The sensitivity of the maximum stable axial depth, blim, to each input parameter at each spindle speed is determined. This enables identification of parameters with high contribution to stability lobe uncertainty. Two methods are used to calculate uncertainty: 1) Monte Carlo simulation; and 2) numerical derivatives of the system eigenvalues. Once the uncertainty in axial depth is calculated, its effect is observed in the MRR and SLE uncertainties. This allows robust optimization that takes into consideration both performance and uncertainty.
Modelling Transient Behavior of a Mechanical System Including a Rolling and Sliding Contact
Authors: So¨derberg Anders , Spiegelberg Christer
Published: April 2008

The friction and wear of rolling and sliding contacts are critical factors for the operation of machine elements such as bearings, gears, and cam mechanisms. In precision machines, for example, the main concern is to compensate for frictional losses, so as to improve control accuracy. In other applications it is often desirable to minimize friction losses to improve efficiency, though sometimes high friction is desired to prevent sliding and wear. The aim of this study is to simulate the behavior of a test equipment and show that simulations can be used to study and optimize mechanical systems that include rolling and sliding contact. Simulations can be used to study the system as a whole, as well as the contact conditions. The test equipment and the measurement procedure used are described. In the simulations, a contact model designed to handle transient contact conditions is integrated into a system model. The results show that the contact strongly influences the system. The simulations show that the use of a contact model allows the simulation of systems that contain contacts with different amounts of slip, and that such simulations can be used to study the contact as well as the system. Surface roughness influences the contact stiffness and is included in the simulations.
Evaporation and Viscous Flow in Triangular Grooves in Micro Heat Pipes
Authors: Markos Mulugeta , Ajaev Vladimir S. , Homsy G. M.
Published: April 2008

We develop a lubrication type model of a liquid flow in a wedge in the limit of small capillary numbers and negligible gravity. The model incorporates the effects of capillary pressure gradients and evaporation. Steady vapor-liquid interface shapes are found for a range of parameters. In the limit of weak evaporation the flow is the same in all cross-sections and can be controlled by changing the wedge angle. We find the wedge angle that results in the maximum value of the flow rate for a given contact angle. For high evaporation rates, both the flow rate and the amount of liquid in each cross-section along the wedge decrease until the point of dry-out is reached. The location of the dry-out point is studied as a function of evaporation. Practical suggestions about optimization of micro heat pipes are given.
Modeling and Control of a 1-D Membrane Strip With an Integrated PZT Bimorph
Authors: Ruggiero Eric J. , Inman Daniel J.
Published: April 2008

Ultra-lightweight, ultra-large and deployable satellite technology is at the forefront of research efforts for future on-orbit reconnaissance missions. The minimal mass and stowage volume associated with the technology are attractive traits for getting larger bandwidth satellites on-orbit. One of the key components for such a satellite is the membrane lens or aperture for optical or radar applications, and understanding the membrane’s dynamics is critical for mission success. As either an optical reflector or radar antenna, the vibration levels of the membrane must be minimized and eliminated. This work examines the possibility of integrating a PZT bimorph near the boundary of a strip sample to eliminate detrimental vibration. By starting with a 1-D model, the dominant governing phenomena of the system dynamics can be established and used to build more complex models with confidence. A physics-based finite element (FE) model of a thin strip of Kapton HN material with a monolithic PZT bimorph bonded near a boundary is developed in a MatLab environment and verified experimentally. The membrane strip under tension is modeled as a beam under axial load. In doing so, the FE model is able to capture the relevant transverse dynamics of the experimental setup. Having verified the FE model, an LQR controller is developed and simulated to demonstrate effective control over the transverse dynamics of the membrane sample.
Control of Electro-Hydraulic Poppet Valves via Online Learning and Estimation
Authors: Opdenbosch Patrick , Sadegh Nader
Published: April 2008

Online learning state trajectory control applied to Electro-Hydraulic Poppet Valves (EHPV) is considered herein. The control problem is to track a desired flow conductance coefficient KV for pressure or flow control applications. In general terms, the control methodology employed herein computes the input signal sent to the valve from the addition of three components. The first component comes from an experimentally approximated inverse input-output map of the system which gives a nominal input. The second component is computed through a neural network structure called the Nodal Link Perceptron Network that learns online the adjustment of this nominal map. The third component is an adaptive proportional feedback control input. This last component uses two system parameters known as the Jacobian and the Controllability parameter, which are estimated online via a recursive least squares algorithm with forgetting factor. The proposed controller is explored through experimental data on a pressure control application and the results are discussed.
Mechanical Testing of Freestanding Nano-Films Using a Novel Finite Diameter Tip MEMS-Based Testing Machine
Authors: Leseman Zayd C. , Sheikh Zuhaib , Mackin Thomas J. , Begley Matthew
Published: April 2008

We present a novel experimental method for measuring the mechanical properties of nano-thickness materials using a freestanding membrane test. Specially fabricated axisymmetric freestanding membranes are centrally deflected using a spherical indenter attached to a custom-designed MEMS load cell. Experiments on freestanding films allows us to determine directly the mechanical properties of the films, over a broad range of length scales, without the confounding effects of a substrate.
Postural Stability of Stand-Up Forklift Operators in Response to Normal Braking Procedures
Authors: Mkandawire Chimba , Nicosia Mark A. , Moor Tara L. A. , Corrigan Catherine F.
Published: April 2008

Balance retention and postural stability of forklift operators have not been well investigated in the literature. Our testing shows that forklift operators can maintain postural stability during routine braking procedures while using standup lift trucks, and that peak acceleration levels generated by lift trucks are below the peak acceleration levels mandated by the Americans with Disabilities Act for moving platforms. Our review of studies involving balance retention has shown that acceleration levels experienced by subjects who maintained postural stability were greater than the peak accelerations during forklift braking operation. In addition, acceleration levels alone are a poor predictor of a subject’s ability to maintain postural stability.
Numerical Investigation of Injury Biomechanics of the Thorax and Lower Extremities Under Different Restraint Systems Using Wayne State University Human Model
Authors: Yoon Jong Young , Lee Seoung Hoon , Cho Young Nam , Park Yong Jae , Lee Jong B. , Yang King H. , King Albert I.
Published: April 2008

Although newer vehicles are equipped with airbags and there is a high percentage of vehicular occupants who are wearing seatbelts, injuries to the thorax and lower extremities accounted for 33% of all occupant injuries. Moreover, when considering the frequency of injuries with a severity on the Abbreviated Injury Scale (AIS) of 3 to 6 (heretofore referred to as AIS 3+), injuries to the chest and lower extremities accounted for a total of approximately 43% of all occupants with these injuries. Consequently, a more detailed study of injury risks to these two body regions is called for. A series of numerical studies has been conducted to simulate a frontal crash using a three-dimensional (3D) finite element (FE) whole body human model representing a 50th percentile male to estimate the injury risks to the thorax and lower extremities. Three different combinations of restraint systems were simulated along with the no restraint condition. Results indicate that injury risks to the thorax were much higher in an unrestrained driver compared to those of a driver restrained by either the airbag only, three-point belt only, or combined airbag and three-point belt condition. On the other hand, injury risks to the lower extremities in occupants without any restraint or airbag only were greater than those restrained by three-point belt only or combined airbag and three-point belt. The combined airbag and three-point belt system simulated in this study showed the lowest injury risks to the thorax and lower extremities.
Surface Acoustic Wave Band Gaps and Phononic Structures on Thin Solid Plates
Authors: Zhang Xinya , Jackson Ted , Lafound Emmanuel , Deymier Pierre , Vasseur Jerome
Published: April 2008

Novel phononic crystal structures on thin plates for material science applications in ultrasonic range (~ MHz) are described. Phononic crystals are created by a periodic arrangement of two or more materials displaying a strong contrast in their elastic properties and density. Because of the artificial periodic elastic structures of phononic crystals, there can exist frequency ranges in which waves cannot propagate, giving rise to phononic band gaps which are analogous to photonic band gaps for electromagnetic waves in the well-documented photonic crystals. In the past decades, the phononic structures and acoustic band gaps based on bulk materials have been researched in length. However few investigations have been performed on phononic structures on thin plates to form surface acoustic wave band gaps. In this presentation, we report a new approach: patterning two dimensional membranes to form phononic crystals, searching for specific acoustic transport properties and surface acoustic waves band gaps through a series of deliberate designs and experimental characterizations. The proposed phononic crystals are numerically simulated through a three-dimensional plane wave expansion (PWE) method and experimentally characterized by a laser ultrasonics instrument that has been developed in our laboratory.
Thermal Optimal Design for Multichip Module Disks With an Unconfined Round-Jet Impingement
Authors: Fang C. J. , Wu M. C. , Peng C. H. , Lee Y. C. , Hung Y. H.
Published: April 2008

An effective method for performing the thermal optimization of stationary and rotating MCM disks with an unconfined round-jet impingement under space limitation constraint has been successfully developed. The design variables of stationary and rotating MCM disks with an unconfined round-jet impingement include: the ratio of jet separation distance to nozzle diameter (H/d), steady-state Grashof number (Grs), jet Reynolds number (Rej), rotational Reynolds number (Rer). The total experimental cases for stationary and rotating MCM disks are statistically designed by the Central Composite Design (CCD) method. In addition, a sensitivity analysis, the so-called ANOVA, for the design factors has been performed. In the stationary MCM disk with an unconfined round-jet impingement, the contribution percentage of jet Reynolds number on the thermal performance is 95.86%. The effect of jet Reynolds numbers on chip temperature distribution is more significant than that of the H/d ratio and steady-state Grashof number. In rotating MCM disk with an unconfined round-jet impingement, the effect of jet Reynolds number, which has the contribution percentage of 91.81%, dominates the thermal performance. Furthermore, the comparisons between the predictions by using the quadratic Response Surface Methodology (RSM) and the experimental data are made. The maximum deviations for transient stagnation Nusselt number and transient average Nusselt number for the cases of stationary MCM disk are 10.05% and 11.82%, respectively; and 9.41% and 12.44% for the cases of rotating MCM disk, respectively. Finally, with the Sequential Quadratic Programming (SQP) technique, a series of thermal optimal designs under space limitation constraint H/d≤12 has been efficiently performed. Comparisons between the numerical optimization results and the experimental data are made with a satisfactory agreement.
Inner-Loop Feedback for Deadband Compensation in Electromechanical Flight Surface Actuation Systems
Authors: Habibi S. R. , Roach J. , Luecke G.
Published: April 2008

This manuscript pertains to the application of an inner-loop control strategy to electro-mechanical flight surface actuation systems. Modular Electro-Mechanical Actuators (EMA) are increasingly used in-lieu of centralized hydraulics for the control of flight surfaces in the aerospace sector. The presence of what is termed as a dead zone in these actuators significantly affects the maneuverability, stability, and the flight profiles of aircrafts that use this actuation concept. The hypothesis of our research is that flight surface actuation systems may be desensitized to the effects of dead zone by using a control strategy with multiple inner-loops. The proposed strategy involves: high-gain inner-loop velocity control of the driving motor; and inner-loop compensation for the differential velocity between the motor versus the aileron. Our results indicate that this strategy is very effective and that it can considerably improve the system’s performance. The above hypothesis is confirmed by theoretical and simulated analysis using the model of an EMA flight surface actuator.
Numerical Modeling of Thermoplastic Films in a Laser Welding Process
Authors: Whalen Richard A. , Kowalski Gregory J.
Published: April 2008

A numerical simulation code is used to investigate the size of the heat affected zone (HAZ) and the onset of thermal damage in a short pulsed transmission laser welding process. The welding process involves the lap welding of two thin 30 microns thick, moving layers, of thermoplastic films. The investigated welding conditions are transparent material over a semi-transparent or opaque material and two transparent materials over a reflective backing. The results provide temperature profiles that illustrate the relationship between; surface cooling, laser intensity, velocity feed rates and material thermo-physical properties.
A Negative Impedance Approach to the Design Synthesis and Control of Multi-Energy Active Elements
Authors: Connolly Thomas J.
Published: April 2008

This paper covers the continuing development and experimental validation of our approach to the design synthesis and control of active devices in dynamic mechanical systems. Active devices, such as electric motors and hydraulic actuators, require an external power input. An innovative feature of this synthesis approach is the use of non-physically realizable elements, i.e., elements that have negative impedances, to model the behavior of an active device. The synthesis method also features the use of bond graphs, as they facilitate modeling of multi-energy systems and devices. The procedure applies to the design or retrofit of systems for which a desired frequency response is prescribed. The overarching goal of the synthesis method is to yield options for the general framework of a controllable, stable, and parameterizable system, using simulation-based techniques. Thus the procedure yields a stable “first draft” of the active device and its control system that can be handed off to respective specialists for further refinement. Simulation results indicate that design possibilities can include purely active devices or a hybrid combination of active and passive elements. In addition, atypical control system architectures, that depart from traditional PI, PD, or PID controllers can arise from the synthesis procedure. We describe validation experiments that use electric motors and rack-and-pinion systems to achieve active control of a quarter-vehicle test article. The results will provide insight into: (1) refining the synthesis procedure to include systems that feature continuous elements, (2) partially automating the synthesis procedure to make it a more versatile design tool, and (3) practical limitations of the synthesis method.
Characterization of Mechanical Behavior of Polyurethane Foams Using Digital Image Correlation
Authors: Jin Helena (Huiqing) , Lu Wei-Yang , Scheffel Simon , Neilsen Michael K. , Hinnerichs Terry D.
Published: April 2008

Polyurethane foams have good energy absorption properties and are effective in protecting sensitive components from damages due to impact. The foam absorbs impact energy by crushing cells and undergoing large deformation. The complex deformation of the foam needs to be modeled accurately to simulate the impact events. In this paper, the Digital Image Correlation (DIC) technique was implemented to obtain the deformation field of foam specimens under compression tests. Images of foam specimen were continuously acquired using high-speed cameras. The full field displacement and strain at each incremental step of loading were calculated from these images. The closed-cell polyurethane foam used in this investigation was nominal 0.32 kg/m^3 (20 pcf). In the first experiment, cubic specimens were compressed uniaxially up to 60%. The full-field displacements and strains obtained using the DIC technique provide detailed information about the inhomogeneous deformation over the area of interest during loading. In the second experiment, compression tests were conducted for a simple foam structure - cubic foam specimens with a steel cylinder inclusion. The strain concentration at the interface between steel cylinder and foam was studied to simulate the deformation of foam in a typical application. In the third experiment, the foam was loaded from the steel cylinder during the compression. The strain concentration at the interface and the displacement distribution over the surface were compared for cases with and without a confinement fixture to study the effects of confinement. These experimental results demonstrate that the DIC technique can be applied to polyurethane foams to study the heterogeneous deformation. The experimental data is briefly compared with the results from modeling and simulation using a viscoplastic model for the foam.
Study on the Drilling of Titanium/Graphite Hybrid Composites
Authors: Kim D. , Ramulu M.
Published: April 2008

Titanium/graphite hybrid composites (TiGr) are a potentially enabling technology which satisfies the low structural weight fraction and long operational lifetime required for the High Speed Civil Transport. TiGr composites are made of thermoplastic polymer matrix composite (PMC) plies with titanium foils as the outer plies. The two materials are assembled by bonding the polymer matrix composite plies and titanium foils to form a hybrid composite laminate. Both experimental and analytical work has been performed to characterize major hole quality parameters and cutting mechanisms encountered in drilling of TiGr composites. The effects of consolidation processing, such as induction heating press and autoclave processe, on drilling characteristics of TiGr composites were examined. The hole quality parameters and hole exit damage was investigated and discussed.
Rapid Mixing in an Overlapping Crisscross Micromixer
Authors: Wang Lilin , Yang Jing-Tang
Published: April 2008

We have developed a novel PDMS-based microfluidic mixer that incorporates an overlapping crisscross entrance with patterned microchannels and that acts as a high-performance micromixer. Such an entrance design generates significant flow tumbling and promotes axial advection between mixing fluids. A systematic numerical analysis reveals the overall mixing trends and the bulk flow structure. The downstream mixing performance is greatly enhanced as a result of the design of the entrance, at which there is vertical advection between mixing fluids, and four split flow zones generated by a staggered floor structure. After flowing through 12 pattern grooves, the mixing indexes of this device range between 0.16 and 0.51. The variation of aspect ratio of the microchannels controls the turning ratio of diverting flow rate versus straightforward flow rate and might be extensible for implementation in a disposable device. The effects of dimensionless control parameters and experimental investigation will be further discussed in the final draft.
High Precision Tracking Control Using Piezoelectric Actuator Network
Authors: Xue X. , Tang J.
Published: April 2008

Although piezoelectric actuators have been widely used in active control, the hysteresis nonlinearity and the non-minimum phase characteristic could potentially deteriorate the system performance, especially in high precision control applications under disturbance. In this study, a resistance/inductance circuit is connected to the piezoelectric actuator to form an actuator network. With the actuator dynamics, the system model can be directly cast into the state-space whereas the system nonlinearity appears as explicit functions of the state variables. We then develop an integral continuous sliding mode control scheme to tackle the hysteresis nonlinearity and the disturbance issues. Instead of inverse hysteresis cancellation which might not be reliable due to the measurement noise, a direct piezoelectric hysteresis compensation can be achieved using this control strategy. The newly developed control scheme combines the advantages of both integral control and continuous sliding mode control with cubic state feedback. Not only can the control action react efficiently and effectively for the non-minimum phase response, but also, a zero steady state tracking error is guaranteed. Detailed analysis and case studies demonstrate that this new methodology can lead to improved tracking control precision, enhanced control robustness, and smoother control action.
Output Feedback Control of Saturated Linear Systems Using Parameter-Dependent Lyapunov Functions
Authors: Zheng Qian , Wu Fen
Published: April 2008

In this paper, we present an output feedback control approach for discrete-time linear systems subject to actuator saturations using parameter-dependent Lyapunov functions. The saturation level indicator serves as a scheduling parameter. The resulting nonlinear controller is expressed in a quasi-LPV form and the controller synthesis problem is formulated and solved as an optimization problem with LMI constraints. Our approach is less conservative than a single quadratic Lyapunov function method. The proposed output feedback control law asymptotically stabilizes the open loop system with a larger domain of attraction and achieves better performance under energy and magnitude bounded disturbances.
Optimal Extension of District Heating Systems Through Thermoeconomics
Authors: Ciano C. , Verda V. , Cali` M.
Published: April 2008

Network extension is an issue in planning district heating systems, specially in a large town; the optimal network does not necessarily connect all the buildings, because of technical and economical reasons. The selection of areas to be connected should be made during the design process, since further variations in the topology are usually difficult and conduct to a non-optimal configuration. This paper deals with the optimal extension of the district heating network using economic criteria. The algorithm here proposed is based on the application of thermoeconomics, together with some concepts derived from the optimization technique called simulated annealing. The algorithm reduces significantly the time required for solving the problem with respect to other optimization techniques such as genetic algorithms. An initial superstructure connecting all the possible users is built. Then the structure is progressively simplified, until the optimal configuration is found. The procedure is applied first to the actual district heating network operating in Turin. The application to a small portion of the central urban area of Turin, at the moment not connected with the DH network. is also proposed. Some general considerations about the optimal network configuration are then obtained by varying the climatic data, the volume of the buildings in the considered area and the distribution of users throughout this area.
Biochemical Mass Detection Using Mode Localization in Microcantilever Arrays
Authors: Spletzer Matthew , Raman Arvind , Reifenberger Ron , Wu Alexander Q. , Xu Xianfan
Published: April 2008

Microcantilever based biochemical sensors rely on accurately detecting the selective binding of small amounts of the target analyte to a functionalized microcantilever. Commonly, the added mass of the bound analyte is detected by measuring accompanying shift in cantilever resonant frequency. In this paper we explore the possibility of using Anderson or mode localization in coupled oscillator arrays as a potentially more sensitive method for detecting the added mass. According to this method, the eigenvectors of an array of coupled, nominally identical cantilevers are expected to be extremely sensitive to small disorder such as that introduced by the added mass of the target biochemical analyte. A simple lumped parameter model of the cantilever array is used to establish theoretical feasibility of the method. The effects on the eigenvector sensitivity of initial statistical variability introduced due to inherent manufacturing tolerances are investigated. Experimental results are presented for a two cantilever array laser fabricated out of gold foil, and the results compared to theoretical expectations. Both the theoretical and experimental results indicate that added mass induced shifts in eigenvectors of such arrays can be orders of magnitude more sensitive than the resonance frequency shifts.
A Mechanical and Electrical Engineering Interdisciplinary Capstone Design Project
Authors: Rocheleau David N. , Dougal Roger A.
Published: April 2008

Since Spring 2000, and running every semester, the University of South Carolina Department of Mechanical Engineering and Department of Electrical Engineering have collaborated on a capstone senior design project. In the beginning, the collaboration was between a junior level mechanical engineering class and the electrical engineering senior capstone design class. The collaboration has evolved and is currently between both departments’ senior capstone design classes. This paper outlines the growth of the collaboration from inception to current state with focus on the recent history of the collaboration. In its current embodiment students from mechanical engineering design, develop, construct and deliver a robotic vehicle platform for electrical engineering students to place a microcontroller for use in the autonomous control of the robotic platform. The integrated and completed robotic platform is used in the Southeastern Conference IEEE student competition held each Spring. The collaboration is considered successful by both departments and is used as a key example of an interdisciplinary design effort between the two departments for ABET review considerations.
A Parametric Study on Injuries to the Knee-Thigh-Hip Complex Using a Three-Dimensional FE Model of the Human Body and Knee Airbag
Authors: Kim Yong Sun , Choi Hyeong Ho , Cho Young Nam , Park Yong Jae , Lee Jong B. , Gundimeda Phalgun , Yang King H. , King Albert I.
Published: April 2008

Although extensive biomechanical studies have been conducted on the knee-thigh-hip (KTH) complex to improve our understanding of its injury mechanisms, injury risks to the KTH complex due to the knee airbag have not been characterized so far. In this study, a detailed three-dimensional (3D) finite element (FE) model of a 50th percentile male KTH complex was integrated into a previously developed torso model and used to simulate frontal crashes with and without a generic knee airbag. The FE model of the KTH complex explicitly represented the ilium, ischium, sacrum, articular cartilage, femoral head, femoral neck, femoral shaft, femoral condyles, patella, patella tendon, and the rest of the leg. The Design of Experiments (DOE) method based on Taguchi’s approach was adopted in this study. The three vehicular interior design parameters considered were knee airbag pressure, knee airbag volume and impact speed. Each of these parameters were assigned three design levels to simulated to predict their respective effects on the potential of KTH injury in a frontal impact.
Estimation of Anisotropic Thermal Conductivity in Nanoscale Confined Semiconductors via Lattice Boltzmann Method
Authors: Ghai Sartaj S. , Kim Woo Tae , Amon Cristina H. , Jhon Myung S.
Published: April 2008

A novel transient thermal transport model based on lattice Boltzmann method is developed to capture the sub-continuum effects including anisotropic thermal behavior of solids at nanoscale. Rigorous boundary condition treatment is incorporated via ghost boundary formulation. These sub-continuum effects deviate significantly from the bulk behavior and can not be accurately captured by the continuum based models such as Fourier equation. We observed that as the thickness of the semiconductor film is decreased to the scale of its carrier’s mean free path, the thermal conductivity of the film reduces drastically from its bulk value and starts to show anisotropic behavior. In addition, a temperature jump, which does not exist at the bulk conditions, is observed at the interfaces. These sub-continuum effects are successfully captured by the lattice Boltzmann model and simple equations have been developed to accurately estimate these effects using the film geometry and properties.
Estimation of a Moving Vehicle’s Position and Orientation Using Probabilistic Data Association
Authors: Lei Yu , Lu Guang
Published: April 2008

This paper presents a computationally efficient algorithm for real-time vehicle tracking, by detecting the two taillights using a laser scanning radar (LIDAR) sensor. It is assumed that the two targets are constrained by fixed known separation distance 2l. To reject clutter, a Probability Data Association (PDA) based algorithm is proposed. The algorithm first predicts the orientation of the vehicle and the position of one of the two targets. Then it uses a two-dimensional PDA filter to estimate the position of this target. All the measurements whose distance from the estimated target is close to 2l are converted into orientation angles. This is followed by a one-dimensional PDA filter, which probabilistically combines calculated angles to estimate the orientation of the vehicle. Simulation results show significant improvement by this algorithm over other methods, in terms of orientation tracking.
A Fuzzy Nonlinear Modeling of a McPherson Suspension System
Authors: Tavassoli Ali , Jafarian Hamed , Eghtesad Mohammad
Published: April 2008

The Takagi-Sugeno fuzzy model (TSfm) is a universal approximation of continuous real functions that are defined in a closed and bounded subset of Rn. This strong property of the TSfm can find several applications in modeling of dynamical systems that are described by differential equations. In this paper, we consider Takagi-Sugeno fuzzy model for a McPherson suspension system. One advantage of TSfm is its wide domain of attraction in compare with the other methods. To apply TSf modeling, one must precisely choose the nonlinear terms of the system governing equations. For each nonlinear term, there should be selected some linear subsystems that together represent the equivalent of the original nonlinear suspension system. This equivalence, for our case study, is illustrated by simulation results for various road disturbances and initial conditions which show the Takagi-Sugeno model can give a realistic and reliable model for dynamical systems.
Automated Occupant Model Evaluation and Correlation
Authors: Liu Xiaoping , Chen Weigang , Paas Michel
Published: April 2008

Rapid advance in computational power and modeling techniques has greatly promoted the application of computer simulations of physical systems in various areas. In the vehicle occupant safety design and analysis, computer models have been widely used to simulate vehicle interior, restraint system and occupants under different crash conditions. However, to ensure the quality of an occupant model engineers often spend tremendous time on model correlation task, especially when correlating multiple occupant injury curves, as in New Car Assessment Program (NCAP), head injury, Chest G, chest deflection, shoulder belt load, femur loads and neck loads and moment etc. all need to be considered. A commonly used approach for model correlation is visual model evaluation and manual model correlation by a trial and error method. This paper develops an automated model correlation program through multiobjective optimization, which is able to achieve a balanced model quality improvement for the multiple responses simultaneously. The developed method has been applied to a real MADYMO model and the results have demonstrated the proposed method is effective and efficient in achieving a high quality occupant model.
Virtual Locator Trimming in Pre-Production: Rigid and Non-Rigid Analysis
Authors: Lindkvist Lars , Carlson Johan S. , So¨derberg Rikard
Published: April 2008

In pre-production, during assembly of newly produced components geometrical deviations, caused by form errors of the parts, are discovered that can cause either functional or esthetical problems. One commonly used way of solving this is to reposition the components by adjusting their locators, also known as trimming. Traditionally this is done by assembling a number of components, measuring the deviations to surrounding parts, adjusting the locator points, reassembling the components and measuring the result. This is repeated until the result is satisfactory, and is a quite time and effort consuming activity. This paper presents a method and a tool that simplifies this process. Based on inspection data from the initial components all trimming activities are performed in the computer tool presented. After the locators are adjusted, the result is presented directly, which eliminates the need for physical inspection in order to verify the result of the trimming. The presented tool also includes optimization of the trimming. By formulating the problem of minimizing the geometrical deviations as a linear least square problem a general optimization package can be used. The optimization handles both boundaries on the allowed trimming and weighting of the different inspection features. By using the method of influence coefficients, also compliant (non-rigid) components can be handled.