bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Transmission Shift Calibration Based on Parallel-Modulated Neural Network (PMNN) Friction Component Model
Authors: Cao M. , Wang K. W. , Fujii Y. , Tobler W. E.
Published: April 2008

The parallel-modulated-neural-network (PMNN) -based friction component model [19] provides a simple pressure-torque formula, which possesses much improved scalability with respect to the applied pressure. In this paper, the PMNN friction component model is implemented within a comprehensive powertrain model, to simulate the shifting process of an automatic transmission (AT) system under various operating conditions. Simulation results demonstrate that the PMNN model can be effectively applied as a part of powertrain system model to accurately predict transmission shift dynamics. A pressure-profiling scheme through a quadratic polynomial pressure-torque relationship from the PMNN model is developed for the transmission shifting optimization. This scheme is implemented to improve the transmission shifting quality under certain operating conditions. The pressure profiling results illustrate that the proposed pressure profiling technique can be potentially applied to a wide range of operating conditions. This study demonstrates that the PMNN architecture not only outperforms the conventional network modeling techniques in accuracy and numerical efficiency, but is also a new tool for AT controller design.
Design and Analysis of Retaining Ring Locking Key Groove in Turbine Generators
Authors: Tong Wei
Published: April 2008

Retaining rings in a turbine generator serve to restrain the rotor endwindings from tremendous centrifugal forces and axial forces experienced at high rotating speeds. The failure of these rings in service can cause catastrophic damage to not just the generator, but to the entire power plant. In order to optimize the generator retaining ring design for enhancing operation reliability, the retaining ring stress analysis was performed using a finite element model. Based on the results, the innovative design of the retaining ring locking key grooves was proposed for achieving favorable stress reduction and cost benefit.
Broad-Band Optical End-Point Detection for Linear Chemical-Mechanical Planarization Processes Using an Image Matching Technique
Authors: Yi Jingang , Xu C. Shan
Published: April 2008

In this paper we discuss an end-point detection (EPD) method for the dielectric linear chemical-mechanical planarization (CMP) processes. The proposed EPD algorithms utilize the interferometry optical signals to determine the film post-thicknesses. A set of collected broadband spectral signals is formed as an spectral image. An image-matching technique is then used to match the pre-processed signal image to the reference image template obtained at the target film thickness. Several matching criteria are discussed and compared. We find that the image correlation coefficient is a good indicator to determine the process end-point. We also consider the impact of the material removal rate variations on the interferometry spectral signals. An analytical calculation is carried out to find an extraction and compression searching range of the spectral image to compensate for the removal rate uncertainties in real processes. The correctness and effectiveness of the proposed algorithms have been demonstrated through applications to an inter-metal dielectric (IMD) device CMP process. Compared with other optical EPD methods, the proposed image-matching method are robust to the CMP process variations.
Investigation of Operator Feedback in Human-Machine Haptic Interfaces for Steer-by-Wire Transportation Systems
Authors: Mandhata U. , Parker R. , Wagner J. , Dawson D. , Post B.
Published: April 2008

The application of haptic technology to the human-vehicle interface permits customization based on the operator’s needs, mission requirements, and surrounding environment. In mechatronic systems, haptics typically encompass force reflecting devices through the integration of sensors, actuators, and real time microprocessor control algorithms. Some transportation-based haptic interface technology examples include ground vehicles, electric wheelchairs, remote-controlled drones, aircraft, and mobile robots. Drive-by-wire vehicles and tele-operated robots can benefit from haptic concepts through the provision of tunable force feedback using servo-motors to upgrade traditional systems such as hydraulic power steering and non-force feedback joysticks. In addition, haptics can potentially improve the operator’s performance and overall system safety. In this paper, driver interface feedback has been studied on a steer-by-wire haptic interface platform integrated with a virtual reality driving environment. Operator performance over a prescribed series of driving maneuvers and feedback settings has been investigated through real time data logging and post-test questionnaires. Finally, external observations have been made on individual driver behavior when subjected to varying steering feedback configurations.
On the Mechanism of Stick and Non-Stick, Periodic Motions in a Forced Linear Oscillator Including Dry Friction
Authors: Luo Albert C. J. , Gegg Brandon C.
Published: April 2008

In this paper, the dynamics mechanism of stick and non-stick motion for a dry-friction oscillator is discussed. From the theory of Luo in 2004, the conditions for stick and non-stick motions are achieved. The stick and non-stick periodic motions are predicted analytically through the appropriate mapping structures. The local stability and bifurcation for such periodic motions are obtained. The stick motions are illustrated through the displacement, velocity and force responses. This investigation provides a better understanding of stick and nonstick motions of the linear oscillator with dry-friction. The methodology presented in this paper is applicable to oscillators with non-linear friction forces.
A Method for Characterizing Elastic Structures in the Mid-Frequency Region
Authors: Shepard W. Steve , Liu Yi
Published: April 2008

This work presents a method for characterizing elastic structures when spatially varying properties over the input and output contact regions are considered. Most analytical or experimental approaches, such as the four-pole parameter method, are limited by the inherent use of lumped quantities to represent critical parameters. When the excitation frequency increases, however, the structural wavelength becomes comparable to the dimensions of the contact region. As a result, the point-quantity assumption is no longer valid. To address this limitation, the work described here reformulates the traditional four-pole method in terms of quantities defined over planes. Consequently, spatial variations across the region connecting the structures can be considered. After the method is derived, it is applied to a simplified engine mount model in which two elastic beams are coupled through a set of elastic and inertial elements. Just like for the four-pole method, the formulation approach uses building blocks for simple structures that can be assembled to represent more complex structures. Some of the potential applications for this method are also discussed. By using this method, a meaningful characterization of the dynamic behavior can be obtained for structures when the frequency increases beyond that for which the point quantity approaches become invalid.
Floor, Wall and Ceiling Approach for Pocket Machining
Authors: Chiou John C. J.
Published: April 2008

This paper presents a floor-wall and ceiling (FWC) approach to determining the tool axes for five-axis machining. The paper focuses on the pocket floor finishing by using ball-end tool. This FWC method generates tool axes by simply linking the corresponding points between tool location paths on floor and tool axial paths on ceiling. The geometry of the floor, wall, and ceiling of a pocket are first discussed. The construction and manipulations of the tool location paths and the tool axial paths are then addressed. The relationship between the tool axis variation and the manipulations are analyzed such that the generated tool axes are guaranteed to be smooth, optimized, and collision-free. Computer illustrations and example demonstrations are shown in this paper. The results reveal that the FWC method can generate much higher quality tool axes than the traditional methods.
Reconstructions of the Knee Following Combined Injury to the Posterior Cruciate Ligament and the Posterior Lateral Structures
Authors: Askew Michael J. , Wiley William B. , Melby Arne , Noe Donald A.
Published: April 2008

The posterior cruciate ligament (PCL) provides primary restraint to posterior tibial translation (1). Knee injuries involving only the PCL usually result in minimal disability, and are commonly treated non-surgically (2). However, combined injuries of the PCL and the posterior lateral structures (PLS) in the knee can result in considerable abnormal posterior laxity and posterolateral rotary instability leading to rapid cartilage degeneration (3). There is consensus that, in most cases, knees with this combined injury require surgical reconstruction.
Weld Analysis Methods for Aerospace Systems
Authors: Mulvihill Robert J. , Lo Yunnhon
Published: April 2008

An example of the application of probabilistic structural analysis to welds is presented below. . The same methodology can be used for probabilistic structural analysis of parent metals in tank structures and other structural components such as supports. The methodology is based on a stress vs. strength model. The results may be used for a comparative analysis of candidate weld process improvements. The model can be incorporated into a probabilistic risk assessment which includes the undesirable impacts of weld failure.
Primary Chip Formation During an Extremely High Speed Micromachining Process
Authors: Jackson M. J. , Hamme C. H. , Hyde L. J. , Robinson G. M. , Sein H. , Ahmed W.
Published: April 2008

The advent of nanotechnology has created a demand for precision-machined substrates so that ‘bottom-up’ nanomanufacturing processes can be used to produce functional products at the nanoscale. However, machining processes must be scaled down by an order of magnitude that requires very stable desktop machine tools to produce precision-machined substrates using cutting tools that are rotated at speeds in excess of one million revolutions per minute. Therefore, the mechanics of chip formation at this scale are critical when one considers the effect of chip formation on the generation of surface roughness on the substrate. The tight curl of a machined chip in orthogonal machining appears to be part of the primary shear process. It is also known that transient tight curl occurs before a secondary shear zone develops ahead of the removal of the chip from the cutting zone. However, continuum models predict that curled chips incorporate stresses due to the establishment of a secondary shear zone. A model is presented in terms of the heterogeneous aspects of continuous chip formation, which shows very good agreement with experimental data.
Bone Tissue Strain and Lattice Strain of HAp Crystals Under Tensile Loading
Authors: Fujisaki Kazuhiro , Tadano Shigeru , Sasaki Naoki
Published: April 2008

Bone tissue is a composite material composed of hydroxyapatite (HAp) and collagen. Because HAp in bone tissue is a crystal structure, the X-ray diffraction method is available to measure the lattice strain of HAp. A relationship between macroscopic bone tissue strain and lattice strain of HAp in a bone specimen was investigated using X-ray strain measurement under tensile loading. The strip specimens were cut from cortical bone in a shaft of bovine femur. As a result, lattice strains of HAp showed lower value than the bone tissue strain. The strain ratio of the HAp crystals to the bone tissue was formulated with an elastic modulus and volume fraction of HAp in the bone tissue.
Dynamics and Stability of Locomotion for Actively Powered Simplest Walkers
Authors: Safak Koray K.
Published: April 2008

In this paper we explore methods to achieve actively powered walking on level ground using a simple 2D walker model. The walker is activated either by applying equal joint torques at hip and ankle, or by an impulse applied at toe-off immediately before heel-strike, or by the combination of both. We show that activating the walker by equal joint torques at hip and ankle on level ground is equivalent to the dynamics of the passive walker on a downhill slope. We calculate the stability of the gait cycle by an analytical approximation to the Jacobian of the walking map. Results indicate that short-period gait cycle always has an unstable eigenvalue, whereas stability of the long-period gait cycle depends on the selection of initial stance angle.
Transient Non-Linear Heat Conduction Solution by a Dual Reciprocity Boundary Element Method With an Effective Posteriori Error Estimator
Authors: Divo Eduardo , Kassab Alain J.
Published: April 2008

A Dual Reciprocity Boundary Element Method is formulated to solve non-linear heat conduction problems. The approach is based on using the Kirchhoff transform along with lagging of the effective non-linear thermal diffusivity. A posteriori error estimate is used to provide effective estimates of the temporal and spatial error. A numerical example is used to demonstrate the approach.
Test Facility for Multiphase Pumps in Serial and Parallel Operation
Authors: Vauth Thorsten , Rausch Tobias , Mewes Dieter , Reichwage Mark
Published: April 2008

Multiphase twin screw pumps are investigated experimentally and theoretically. A test facility with two screw pumps that can be continuously operated with water, oil and air mixtures is used to measure the delivering characteristics and the influence of recirculation on pump performance. Unsteady flow regimes like slug flow often occur in natural oil and gas processing. Therefore the operational behavior of the multiphase pumps is investigated for this case. In the development of new oil fields multiphase pumps are installed not only individually but also in pipeline networks. Serial operation of two srew pumps is investigated for steady and unsteady flow conditions. In addition to experiments a model to calculate the volumetric efficiency of the pumps is presented. The calculated results are compared to measured ones.
Wearable Conductive Fiber Sensors for Continuous Joint Movement Monitoring
Authors: Gibbs Peter , Asada H. Harry
Published: April 2008

This paper describes a technique that uses conductive fibers as part of a wearable sensor for continuous monitoring of joint movements. Conductive fibers are incorporated into flexible, skin-tight fabrics that are comfortable and acceptable for long-term wear in everyday settings. Continuous monitoring of single or multi-axis joint movement is therefore possible, even when not in the presence of a therapist. A brief overview of the sensor design is presented, including functional requirements and important design parameters. Misalignment errors that may be created every time the subject takes off and puts on the wearable sensor are accounted for by incorporating an array of fiber sensors around the joint and analyzing each sensor’s sensitivity to joint movement during use. This eliminates any need for re-calibration after an initial calibration.
On the Teaching of Condensation Heat Transfer
Authors: Arnas A. O¨zer , Boettner Daisie D. , Benson Michael J. , Van Poppel Bret P.
Published: April 2008

The topic of condensation heat transfer is usually included in a chapter on Boiling and Condensation in most Heat Transfer textbooks. The assumptions made are those of laminar liquid film with constant thermo-physical properties, uniform vapor temperature equal to the saturation temperature of the vapor, negligible shear at the liquid-vapor interface, and negligible momentum and energy transfer by advection in the condensate film. The results presented are normally for the film thickness, the local convective heat transfer coefficient, and the Nusselt number. However, no means are presented to the student to determine if all of these simplifying assumptions are actually satisfied for a given problem. This investigation clarifies these points to improve teaching of the material and understanding by the student at the undergraduate and graduate level.
Function-Block Enabled Job Shop Planning and Control With Uncertainty
Authors: Wang Lihui , Liu Zhenkai , Shen Weiming , Lang Sherman
Published: April 2008

The objective of this research is to develop a methodology of distributed process planning and its execution control for job shop operations. The manufacturing processes of job shop operations are rather complex, especially at shop floors where highly mixed products in small batch sizes are handled simultaneously. In addition to the fluctuating job shop operations, unpredictable events like job delay, urgent job insertion, fixture shortage, missing tool, and even machine break-down, are regularly challenging the job shop operations. Targeting the fluctuations, this research proposes a DPP (distributed process planning) approach to generate process plans that are responsive and adaptive to the changes. In this paper, a function block enabled approach is introduced. It is expected that the new approach can largely enhance the dynamism of fluctuating job shop operations.
Liquid Water Transport in Polymer Electrolyte Fuel Cells With Multi-Layer Diffusion Media
Authors: Pasaogullari Ugur , Wang Chao-Yang , Chen Ken S.
Published: April 2008

A two-phase, multi-component, full cell model is developed in order to analyze the two-phase transport in polymer electrolyte fuel cells with multi-layer cathode gas diffusion media, consisting of a coarse gas diffusion layer (GDL) (average pore size ~ 10 μm) and a micro-porous layer (MPL) (average pore size ~ 0.2–2 μm). The relevant structural properties of MPL, including average pore size, wettability, thickness and porosity are examined and their effects on liquid water transport are discussed. It is found that MPL promotes back-flow of liquid water across the membrane towards the anode, consequently alleviating cathode flooding. Furthermore, it is seen that unique porous and wetting characteristics of MPL causes a discontinuity in the liquid saturation at MPL-GDL interface, which in turn reduces the amount of liquid water in cathode catalyst layer-gas diffusion medium interface in some cases. Our analyses show that the back-flow of liquid water increases with the increasing thickness and decreasing pore size, hydrophobicity and bulk porosity of the MPL.
Transport Phenomena and Defect Formation in Laser Welding of Zinc-Coated Steels
Authors: Zhou J. , Tsai H. L. , Wang P. C.
Published: April 2008

Zinc-coated steels are used extensively in the auto industry because they are inexpensive, durable and have high corrosion resistance. Lasers are being used to weld zinc-coated steels due to high welding speed, small seam and narrow heat affected zone. However, it is difficult to laser weld lap-joint zinc-coated steel sheets under a very small gap condition between the metal interfaces since there is a considerable amount of zinc vapor generated. This vapor must be vented out; otherwise it will be trapped in the weld pool leading to different welding defects, such as large voids at the tip of the weld and porosities in the form of small bubbles in the weld. These defects can significantly decrease the strength of the weld. In this paper, a mathematical model and the associated numerical techniques have been developed to study the transport phenomena in laser welding of zinc-coated steels. The volume-of-fluid (VOF) method is employed to track free surfaces. The continuum model is used to handle the liquid phase, solid phase and mushy zone of the metal. The enthalpy method is employed to account for the latent heat during melting and solidification. The transient heat transfer and melt flow in the weld pool during the keyhole formation and collapse processes are calculated. The escape of zinc vapor through the keyhole and the interaction between zinc vapor and weld pool are studied. The aforementioned weld defects are found to be caused by the combined effects of zinc vapor-melt interactions, keyhole collapse and solidification process. By controlling the laser pulse profile, it is found that the keyhole collapse and solidification process can be delayed, allowing the zinc vapor to escape, which results in the reduction or elimination of weld defects.
Ultrafast Photon-Electron Interactions in Dielectrics by a Single Laser Pulse
Authors: Jiang L. , Tsai H. L.
Published: April 2008

This study develops a quantum mechanical model to investigate energy absorption in ultrafast laser of dielectrics. The model investigates the optical property variations, electron temperature, and density changes at femtosecond scales. The ionizations and electron heating are two major factors considered for pulse absorption occurring within the pulse duration. The flux-doubling model is employed to calculate the free electron generation mainly through impact ionization and photoionization. The quantum mechanical treatments are used to account for the specific heat and the relaxation time for free electrons. The time and space dependent optical properties of the dense plasma generated by the ultrafast laser pulse are calculated. The predictions of ablation threshold and ablation depth of fused silica and barium aluminum borosilicate (BBS) are in good agreements with published experimental data. The model greatly improves the accuracy in predicting the ablation depth and can predict the crater shape.
Analysis of Side Release Motor Vehicle Seat Belt Buckles
Authors: Clarke Richard , Sances Anthony , Kumaresan Srirangam , Syson Steve
Published: April 2008

The purpose of the current study was to evaluate the likelihood of inertial release of various production side release automotive seat belt buckles under acceleration loading conditions that could be expected to occur in real world accident events. Each test sample was secured to a specially designed vertical acceleration test fixture. This produced a rigid mount, which allowed impacts to be transmitted to the test buckle. A commercially available M/RAD 0909 Pneumatic Shock Machine was used to control the magnitude, shape and duration of the pulses transmitted to the fixture and test buckle. To measure and analyze the shock pulse generated by the M/RAD Pneumatic Shock Machine, an M/RAD SRA-1200 Shock Instrumentation System was used with the capacity to capture, display and analyze half-sine, saw tooth and square wave pulses. A display screen and computer printouts record peak accelerations, pulse durations and change in velocity. An ICP 305A04 accelerometer was attached to the base of the test fixture. All information was recorded at a rate of 8 kHz and was filtered using a digital four pole Butterworth zero phase shift filter, and a low pass filtering system set at L-P1 with a cutoff of 1100 Hz. The current test fixture was designed to accommodate various production side release buckles with interchangeable jaw plates, for the different style buckles, to provide a “rigid mount.” A constant load can be placed on the latch plate and can be varied from 4 to 133 N. The forces for a fixed latch side buckle did not open upto accelerations of about 480 G’s. In contrast, unprotected side release buckle released at accelerations of about one fourth that of protected.
A Collaborative Interdisciplinary Teaching and Learning Project: A Capstone Experience
Authors: Schmidt Klaus , Stier Kenneth W.
Published: April 2008

Students studying web-development need experience in providing their expertise to people with limited Internet experience. On the other hand, students studying manufacturing management need experience to communicate ideas and concepts such as engineering drawings and tooling plans to non-engineering students. Based on this need, two faculty members developed an interdisciplinary collaborative project reflecting the essential elements of successful collaboration in teaching and learning. Students enrolled in either a web-development or a manufacturing course participated in this study. These students were working in interdisciplinary teams producing engineering drawings and production plans that were to be displayed and disseminated via interactive websites. As part of the challenge, students were required to use Internet tools such as chat rooms and discussion forums, to meet the outside-the-classroom communication component.
A Numerical Study of Single Bubble Dynamics During Flow Boiling
Authors: Li Ding , Dhir Vijay K.
Published: April 2008

Nucleate flow boiling is a liquid-vapor phase-change process associated with high heat transfer rates. A complete 3D numerical simulation of single bubble dynamics on surfaces inclined at 90°, 45° and 30° to the horizontal line and subjected to forced flow parallel to the surface is performed in this work. The continuity, momentum and energy equations are solved with finite difference method and the level-set method is used to capture the liquid-vapor interface. The heat transfer contribution of the micro-layer between the solid wall and evolving liquid-vapor interface is included in this numerical analysis. The effect of dynamic contact angle is also included. The numerical result of bubble growth and sliding distance have been compared with experimental data.
Pool Boiling Heat Transfer From Artificial Micro-Cavities Surface in Dielectric Liquid FC-72
Authors: Yu C. K. , Lu D. C. , Cheng T. C. , Tsai B. C.
Published: April 2008

Pool boiling heat transfer phenomenon of artificial micro-cavity enhanced surfaces by wet etching MEMS fabrication immersed in a saturated dielectric fluid has been experimentally studied. The present research is to investigate pool boiling behavior including heat transfer performance and flow pattern of “artificial micro cavities” heating surfaces simulating microelectronic devices at atmospheric pressure with FC-72 as the working fluid. The test surfaces are the solid silicon based blocks with 200 μm diameter circular cavities with flat plane, 16 × 16, 25 × 25, 33 × 33 array and 50 μm depth. Effects of this double enhancement technique on critical heat flux (CHF) and nucleate boiling heat transfer in the horizontal orientation (microcavities are vertical) were also investigated. Results indicated that, in general, increasing the number of micro cavities also increase the enhanced surface area and it could increase the critical heat flux. The pronounced increase of boiling heat transfer coefficients with the application of the artificial micro-cavity to the heat surface were also investigated in this paper.
Micromechanical Modeling of Functionally Graded Composites
Authors: Yin H. M. , Sun L. Z. , Paulino G. H.
Published: April 2008

A micromechanics-based elastic model is developed for two-phase functionally graded materials with locally pair-wise interactions between particles. While the effective material properties change gradually along the gradation direction, there exist two microstructurally distinct zones: particle-matrix zone and transition zone. In the particle-matrix zone, pair-wise interactions between particles are employed using a modified Green’s function method. By integrating the interactions from all other particles over the representative volume element, the homogenized elastic fields are obtained. The effective stiffness distribution over the gradation direction is further derived. In the transition zone, a transition function is constructed to make the homogenized elastic fields continuous and differentiable in the gradation direction. The model prediction is compared with other models and experimental data to demonstrate the capability of the proposed method.
Microfluidic Mixing Through Sequential Sample Injection With Rapid Expansion
Authors: Coleman Jeffrey T. , Sinton David
Published: April 2008

A novel micromixing strategy is presented which exploits axial diffusion of a continuous sequence of discrete samples in a microchannel expansion. Mixing of a continuous sequence in an electroosmotic flow through a sudden expansion region is modelled first assuming an ideal, square-wave injection. Different expansion geometries are examined as well as different sample lengths in order to determine the potential effectiveness of the mixing technique. To facilitate sequential injection on-chip, a new injection scheme is developed. The two outputs from the injector and an expansion region are integrated into a sequential injector micromixer chip design. Results for the sequential injection micromixer demonstrate rapid axial mixing of the individual stream sequences. However, cross-stream gradients in the output channel develop due to an inherent bias in the injection technique. Microchannel configurations that mitigate this bias were presented.
Designing Aspects of a Frontal-Sinusoidal Transmission With Balls
Authors: Bara Mircea
Published: April 2008

The frontal-sinusoidal transmission with balls is a new type of mechanical transmission, that allows movement transmission between two coaxial shafts. In the first part of this paper presents the geometric and kinematics study of the elements of a frontal -sinusoidal transmissions with balls, determining in this way the transmission ratios. In the second part of this paper presents the kinetostatic study of the elements of frontal transmission with balls, determining in this way the force that acts upon these forces which are necessary in the constructive dimensioning. An advantage of this transmission, as compared to other mechanical transmissions, is given by the possibility to obtain more transmission ratios. In case all disks of simple frontal-sinusoidal transmission are moving elements a differential transmission it obtained. Another advantage is given by the possibility of obtaining complex transmissions by series and/or parallel arrangement of frontal transmission simple units.
New Image-Based System for Vibration Measurement, Specially Developed for Forced Human Vibration Analysis
Authors: Hoviattalab Maryam , Narimani Roya , Yadollahi Azadeh , Abadpour Arash
Published: April 2008

The human being in the environments of modern technology has to endure stresses of many and varied kinds of vibrations [1]. Measuring vibration is an important tool in rehabilitation and biomechanical fields of research. We have proposed image processing as a new method to record and determine the frequency response of human body. The subjects were exposed to whole body periodical vibration while standing on a shaking table. Two digital camcorders were used to capture the motion of colored pencil-dot markers on the skin of human body (forehead) and on the edge of the shaking table. After color spotting each frame, the binary image results were processed using new circle factor criteria proposed in this work, for fast finding circles based on second order statistics. The extracted points were calibrated using our own extended version of the direct linear transformation (DLT) method. We subsequently used Borland Delphi 5.0 language to develop useful software for measuring and analyzing human body vibration. As a result, it was clear that the proposed method was lower noise-sensitive in comparison to accelerometer. In order to investigate the validity of the software, the obtained mechanical impedance of the body were compared with other investigations in literature and showed to be compatible. The main advantage of this method is working with a simple user-familiar hardware with no external device attached to the subject and also a user-friendly-software.
Taylor-Couette Instabilities in Partially-Obstructed Annular Spaces With Inner Cylinder Rotation
Authors: Loureiro Bruno V. , Souza Mendes Paulo R. , Azevedo Luis F. A.
Published: April 2008

The flow inside a horizontal annulus due to the inner cylinder rotation is studied. The bottom of the annular space is partially blocked by a plate parallel to the axis of rotation, thereby destroying the circumferential symmetry of the annular space geometry. This flow configuration the drilling process of horizontal petroleum wells, where a bed of cuttings is deposited at the bottom part of the annulus. The velocity field for this flow was obtained both numerically and experimentally. In the numerical work, the equations which govern the three-dimensional, laminar flow of both Newtonian and power-law liquids were solved via a finite-volume technique. In the experimental research, the instantaneous and time-averaged flow fields over two-dimensional meridional sections of the annular space were measured employing the particle image velocimetry (PIV) technique. Attention was focused on the determination of the onset of secondary flow in the form of distorted Taylor vortices. The results showed that the critical rotational Reynolds number is directly influenced by the degree of obstruction of the flow. The influence of the obstruction is more perceptible in Newtonian than non-Newtonian fluids. The larger is the obstruction, the larger is the critical Taylor number. The height of the obstruction also controls the width of the vortices. The calculated steady state axial velocity profiles agreed well with the corresponding measurements. Transition values of the rotational Reynolds number are also well predicted by the computations. However, the measured and predicted values for the vortex size do not agree as well. Transverse flow maps revealed a complex interaction between the Taylor vortices and the zones of recirculating flow, for moderate to high degrees of flow obstruction.
A DNA Hybridization Chip With Electrokinetically-Based Single Nucleotide Polymorphism (SNP) Discrimination
Authors: Erickson David , Liu Xuezhu , Venditti Roberto , Krull Ulrich , Li Dongqing
Published: April 2008

Biosensors and more specifically biochips exploit the interactions between a target analyte and an immobilized biological recognition element to produce a measurable signal. Systems based on surface phase nucleic acid hybridization, such as modern microarrays, are particularly attractive due to the high degree of selectivity in the binding interactions. In this work an electrokinetically controlled poly(dimethylsiloxane) based DNA hybridization microfluidic chip is presented. The electrokinetic delivery technique provides the ability to dispense controlled sample sizes to the hybridization array for quantitative analysis while serving to increase the mass transfer rate and therefore reduce the overall analysis time. An automatic, electrokinetically based, single-nucleotide polymorphism (SNP) discrimination technique (that takes advantage of the combined effects of joule heating, applied potential field and the shear gradients within the double layer field on the thermodynamic stability of the target: probe complex) will also be described for the first time. The clinical utility of the technique will be demonstrated through the detection of genetic markers associated with spinal muscular atrophy, specifically the common C←T mutation in the SMN1 gene.
An Approach to Product Family Planning Based on Hypergraph Theory
Authors: Wang Hong-Jun , Chen Xin , Zheng De-Tao
Published: April 2008

A widespread method employed in product planning is to use quality function deployment (QFD), which provides a means of translating a single customer’s needs into a product’s design requirements. Whereas, mass customization oriented product family planning should translate a group of different customers’ needs into all kinds of engineering characteristics in a product family life cycle by mapping the complicated information between adjacent stages of a product family development cycle so that the customer group’s needs can be carried out in a product family, which needs to develop a batch of products at the same time. Unfortunately, there is lack of a tool to supporting the product family planning at present. Aiming at this problem, this paper proposes a new approach to extend the house of quality (HoQ) in order to fulfill the product family planning for mass customization. Firstly, hypergraph (HG) theory and QFD are brought together, and the processes of information mapping between the adjacent stages of a product family development cycle are described through a relational hypergraph (RH). Secondly, primary-input driven paths in a relational hypergraph, which represent the different information at the same domain in a HoQ, are placed on the left or at the bottom of a HoQ, and secondary-input paths in a relational hypergraph, which represent the different information at the adjacent domain in a HoQ, are placed at the middle array of a HoQ, an extended HoQ (EHoQ) is obtained according to the method described as above, which provides the tool of planning a batch of products at the same time. Finally, the process of translating a group of different customer group’s needs into engineering characteristics is illustrated by means of an EHoQ.
Comparison of Analytical Model to Experimental Results and Numerical Simulations for Tailor Welded Blank Forming
Authors: Bravar Matt , Kinsey Brad , Krishnan Neil
Published: April 2008

Tailor Welded Blanks offer several notable benefits including decreased part weight, reduced manufacturing costs, and improved dimensional consistency. However the reduced formability and other characteristics of the forming process associated with TWBs has limited the industrial utilization of this blank type. One concern with TWB forming is that weld line movement occurs which alters the final location of the various materials in the TWB combination. In this paper, an analytical model to predict the initial weld line placement necessary to satisfy the desired, final weld line location is presented. Good agreement between the model, experimental results, and numerical simulations with respect to weld line movement and initial placement was obtained for a symmetric, steel TWB case and a non-symmetric, Aluminum TWB case.
Simulation of a Crash Test of Minnesota’s Aluminum Type III Barricade
Authors: Paulsen Gale L. , Reid John D.
Published: April 2008

Full-scale crash testing was performed on Minnesota’s Aluminum Type III Barricade by the Midwest Roadside Safety Facility. Testing consisted of an 820 kg vehicle impacting the barricade at two positions, 0 and 90-degrees, at 100 km/h. This paper documents the modeling effort to simulate the physical crash events using LS-DYNA, a nonlinear finite element analysis program. As is typical for vehicle crash simulation, there were many modeling issues that needed careful attention. Four items of particular concern were (1) contact snagging - the barricade kept hooking on the hood with edge to edge snagging; (2) placement of barricade - small adjustments to the impact location could cause the tire to run over one of the barricade legs, which did not happen during the testing; (3) contact friction - the friction between the barricade and the front of the vehicle played an important role in how the barricade wrapped around and flipped off of the vehicle, and (4) sandbag weight - the weight of the sandbags, which are placed on the legs of the barricade and are used to prevent the barricades from being moved by the wind, makes a difference on how the sign legs flip up into the air when impacted by a vehicle. Simulation results are shown to be fairly accurate for both impact conditions. Future studies on various barricade configurations are now possible using the model developed during this research.
Model-Based Fuel Optimal Control of Hybrid Electric Vehicle Using Variable Structure Control Systems
Authors: Wei Xi , Utkin Vadim , Rizzoni Giorgio , Guzzella Lino
Published: April 2008

Hybrid electric vehicles provide promising alternatives to conventional engine-powered vehicles, offering improvements in fuel economy and emissions. Realization of these benefits depends, in part, upon proper control of the vehicle. This paper examines a variable structure control which switches between two operating points. The resulting sliding optimal control provides a better energy management strategy than that obtained conventionally from Pontryagin’s minimum principle. One of the operating points is zero engine power, thus the sliding optimal control is referred to as engine start-stop. Contrary to the general impression that the engine should stop at low speeds or during decelerations, new studies show that engine start-stop also improves fuel economy during highway cruising. The main contribution of this paper is to show that this “duty-cycle” operation mode is indeed optimal. The main tool used in the proof is Pontryagin’s minimum principle.
An Improved Reissner-Mindlin Plate Theory for Composite Laminates
Authors: Yu Wenbin
Published: April 2008

An improved Reissner-Mindlin theory for composite laminates without invoking ad hoc kinematic assumptions is constructed using the variational-asymptotic method. Instead of assuming a priori the distribution of three-dimensional displacements in terms of two-dimensional plate displacements as what is usually done in typical plate theories, an exact intrinsic formulation has been achieved by introducing unknown three-dimensional warping functions. Then the variational-asymptotic method is applied to systematically decouple the original three-dimensional problem into a one-dimensional through-the-thickness analysis and a two-dimensional plate analysis. The resulting theory is an equivalent single-layer Reissner-Mindlin theory with an excellent accuracy comparable to that of higher-order, layerwise theories. The present work is extended from the previous theory developed by the writer and his co-workers with two sizable contributions: (a) six more constants (33 in total) are introduced to allow maximum freedom to transform the asymptotically correct energy into a Reissner-Mindlin model; and (b) the semi-definite programming technique is used to seek the optimum Reissner-Mindlin model. Furthermore, it is proved the first time that the recovered three-dimensional quantities exactly satisfy the continuity conditions on the interface between different layers and traction boundary conditions on the bottom and top surfaces. It is also shown that that two of the equilibrium equations of three-dimensional elasticity can be satisfied asymptotically, and the third one can be satisfied approximately so that the difference between the Reissner-Mindlin model and the second order asymptotical energy can be minimized. Numerical examples are presented to compare with the exact solution as well as the classical lamination theory and first-order shear-deformation, demonstrating that the present theory has an excellent agreement with the exact solution.
Analysis of Interface Between Newtonian and Non-Newtonian Fluids Inside Annular Eccentric Tubes
Authors: Dutra Eduardo S. S. , Naccache Moˆnica F. , Souza Mendes Paulo R. , Souto Carlos A. O. , Martins Andre´ Leibsohn , de Miranda Cristiane Richard
Published: April 2008

In this work, flow of two adjacent fluids through annular eccentric tubes is analyzed numerically. This kind of flow is found in cementing processes of oil wells, where the cement paste pushes the drilling mud through annular space between the drilling column and the oil well wall. Both drilling mud and cement paste behave as non-Newtonian fluids, and between then a wash fluid is usually used, to avoid their contamination. The analysis of interface configuration between these fluids helps to determine contamination, and is an important tool for the process optimization. The numerical solution of the governing conservation equations is obtained via the finite volume technique and the volume of fluid method, using the Fluent software (Fluent Inc.). The effects of rheological parameters and eccentricity are investigated, for different flow rates. The results obtained show that the displacement is better when a more viscous fluid is used to push the other fluid. Also, it is observed that the interface shape is a function of flow regime and viscosities ratio. However, it is insensitive to eccentricity.
Analysis of Viscoelastic Flows Through Converging-Diverging Channels
Authors: Lane Mauricio , Naccache Moˆnica F. , Souza Mendes Paulo R.
Published: April 2008

In this work, the flow of viscoelastic fluids through axisimmetric converging-diverging channels is analyzed. The solution of mass and momentum conservation equations is obtained numerically via finite volume technique using the Fluent software. The Generalized Newtonian Fluid constitutive equation was used to model the non-Newtonian fluid behavior, using the Shunk-Scriven model for the viscosity, where a weighted geometric mean between shear and extensional viscosities is assumed. The results of pressure drop are compared to the ones predicted by a previously proposed simplified relation (Souza Mendes and Naccache, 2002) between pressure drop and flow rate, for viscoelastic fluids flow through porous media, in order to analyze its performance.
Numerical and Experimental Investigation of the Melt Casting of Explosives
Authors: Sun Dawei , Garimella Suresh V. , Singh Sanjeev , Naik Neelam
Published: April 2008

Melt casting of energetic materials is investigated, and a numerical model formulated for the analysis of the coupled fluid flow, heat transfer, and stress fields involved in this phase-change process. The numerical model is based on a conservative multi-block control volume method. The SIMPLE algorithm is employed along with an enthalpy method approach to model the solidification process. Results from the model are verified against experimental data as well as published numerical results for simplified cases. In the melt casting of RDX-binder mixtures, the very high viscosity of the melt leads to the influence of melt convection being very limited. The impact of different cooling conditions on the velocity, temperature and stress distributions, as well as on the solidification time, are discussed. The model can be used to improve the quality of cast explosives, by optimizing and controlling the processing conditions.
Membraneless Liquid-Fuel Microfluidic Fuel Cells: A Computational Study
Authors: Bazylak Aimy , Sinton David , Djilali Ned
Published: April 2008

Presented in this paper is a computational analysis of a membraneless microfluidic fuel cell that uses the laminar nature of microflows to maintain the separation of fuel and oxidant streams. The fuel cell consists of a T-shaped microfluidic channel with liquid fuel and oxidant entering at separate inlets and flowing in parallel without turbulent or convective mixing. Electrodes are placed along the walls, and the resulting redox reactions provide the cell voltage and current. A concise electrochemical model of the key reactions and appropriate boundary conditions for the computational fluid dynamic (CFD) modelling of this system are developed and implemented into the numerical model. The coupled flow, species transport and chemical aspects of the microfluidic fuel cell are simulated. The effects of geometry and flow rates on fuel cell performance are investigated. Results indicate that the microfluidic fuel cell performance is limited by the transport of reactants through the concentration boundary layer to the electrodes. Three typical geometries were simulated, and it was found that increasing the aspect ratio of the channel cross-section from a square geometry to a rectangular one leads to more than a two-fold increase in fuel utilization. The two rectangular geometries simulated consist of a design with a high aspect ratio in the direction perpendicular to the plane of cross-stream diffusion as well as a design with a high aspect ratio in the direction parallel to the plane of cross-stream diffusion. The electrode placement and geometry play key roles with respect to mixing and fuel utilization. The design with a high aspect ratio in the direction perpendicular to the plane of cross-stream diffusion demonstrated relatively less cross-stream mixing compared to the other rectangular geometry, and had the potential for improved fuel utilization with appropriate electrode design. In addition, results suggest that fuel utilization can be increased from previous values by a factor of two or more. Decreasing the inlet velocity from 0.1 m/s to 0.02 m/s caused the fuel utilization to increase non-linearly from 8 % to 23 %, and only caused an increase of 3 % in cross-stream mixing at the outlet.