bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Nonlinear Variation Accumulation in Auto-Body Assembly Process
Authors: Lian Jun , Lin Zhongqin , Yao Fusheng , Lai Xinmin
Published: June 2008

In the assembly process of auto-body, variations in the geometrical dimensions of sheet metal parts and fixtures are inevitable. These variations accumulate through the multi-station assembly process to form the dimensional variations of the final products. Compared with the assembly of rigid parts, the assembly process of the elastic parts is more complex because the variation accumulation patterns rely much on the variations of fixture, jointing methods and mechanical deformation. This paper aims at analyzing the variation transformation mechanism and accumulation characteristics for the assembly of sheet metal parts based on the analysis of dimensional coordination relations among parts and fixtures. Finite element method (FEM) and Monte-Carlo Simulation (MCS) were used to analyze the effect of jointing contact on variation transformation, while a state equation was developed to describe the variation accumulation mechanism. The result of the analysis indicates that the main characteristics of elastic assembly jointing are the overlap jointing methods and elastic contacts action. The fact that the variation transform coefficients (VTC) are variable makes the assembly variation distribution Non-Gaussian even if the dimension variation of parts is Gaussian distribution. The analysis conclusions have potential value for more reasonable tolerance synthesis of elastic parts assembly.
Diagnosability Analysis of Multi-Station Manufacturing Processes
Authors: Ding Yu , Shi Jianjun , Ceglarek Dariusz
Published: June 2008

Variation propagation in a multi-station manufacturing process (MMP) is described by the theory of “Stream of Variation.” Given that the measurements are obtained via certain sensor distribution scheme, the problem of whether the stream of variation of an MMP is diagnosable is of great interest to both academia and industry. We present a comprehensive study of the diagnosability of MMPs in this paper. It is based on the state space model and is parallel to the concept of observability in control theory. Analogous to the observability matrix and index, the diagnosability matrix and index are first defined and then derived for MMP systems. The result of diagnosability study is applied to the evaluation of sensor distribution strategy. It can also be used as the basis to develop an optimal sensor distribution algorithm. An example of a three-station assembly process with multi-fixture layouts is presented to illustrate the methodology.
Finite Element Simulations of Joints Used in the Automotive Industry
Authors: Bhalerao Rishikesh , Heers Brad , Bohm Mark , Schrank Marc
Published: June 2008

Finite element-based simulations of vehicle body systems are an effective means of optimizing a design. However, body systems often consist of components from a variety of sources. Hence, accurate modeling requires a robust set of analysis functionality for joining such components. Joints—such as welds, bolts, rivets, clinches, and adhesives—present unique challenges to the analyst. Despite the critical influence joints have on functional performance, there is little information on best practices for modeling such connections. This paper presents a survey of some of the approaches available in ABAQUS, a general-purpose commercial finite element code, and discusses various applications of these techniques through a series of case studies. While the modeling techniques discussed in this paper have been motivated largely by automotive applications, they are also applicable to other areas such as aerospace structures.
A Novel Annular Dorsal Skin Flap Chamber Freezing Apparatus
Authors: Elliott Gloria , McGrath John
Published: June 2008

One of the challenges in using a dorsal skin flap chamber (DSFC) to study freeze injury in rodents is to achieve a controlled and well-characterized cryolesion within the ∼1 cm viewing area. A novel freezing device was designed that allowed optical access to the DSFC tissue, thus permitting the simultaneous use of various imaging methods (e.g. fluorescence, infrared) throughout a cryosurgery procedure. Stainless steel annuli were implemented with an internal 2.3 mm channel for circulation of cold nitrogen vapor. Inlet and outlet ports were manufactured from hypodermic needles. A machined external groove on the surface of these rings provided the point of attachment for interfacing with each side of the DSFC. Using thermocouples and numerical modeling, temperature gradients in the viewable tissue were estimated to be less than 1°C/mm and highly reproducible freezing rates between 3 and 9 °C/min were achieved in the tissue. At the fastest pump rates the apparatus was capable of producing temperatures as low as −110 °C on the inner surface of the chamber. When these rings were cooled to their lowest temperatures and placed in contact with the DSFC, tissue cooling rates of ∼75 °C/min could be achieved. Numerical modeling results demonstrated that the temperature gradient throughout the thickness of the tissue was minimal, suggesting that surface temperature measurements would be representative of the temperature throughout the thickness of the intravital preparation.
The Role of Microstructure in MEMS Deformation and Failure
Authors: Buchheit T. E. , Boyce B. L. , Wellman G. W.
Published: June 2008

MEMS technologies create complex devices with critical dimensions on the order of 1–100μm from alimited, but expanding materials base. Two standard MEMS technologies of interest to Sandia National Laboratories are surface micromachining (SMM) and LIGA-based high aspect ratio microfabrication. SMM techniques produce complex devices on the surface of a silicon wafer with critical dimensions of about 2μm using a patterned multilayer film deposition process. LIGA (Lithographie, Galvanoformung, Abformung) is a process in which structural material is electrodeposited into a polymethyl-methacrylate (PMMA) mold realized by deep x-ray photolithography. The resolution of the LIGA process can be as precise as 1μm, but typical component sizes range in the 100’s of microns. In both technologies, material microstructural features, e.g. grains and defects, scale with component sizes. Consequently, issues surrounding the mechanical response of components fabricated from these technologies are often caused by this microstructure-component size scale equivalence. The objective of this paper is to present an overview of select mechanical properties results and associated microstructure evaluations expected to be useful for developing damage mechanics models that accurately predict the lifetime of MEMS devices. A companion paper (IMECE2002-32393) discusses experimental results and observations from micromechanical evaluation studies of SMM-MEMS. This paper discusses experimental results and observations on LIGA fabricated materials and some complementary, straightforward polycrystal elastic deformation simulations of SMM polysilicon.
A Virtual Prototyping Framework for Electronics Manufacturing
Authors: Cecil J. , Kanchanapiboon A.
Published: June 2008

This paper presents a framework for supporting virtual prototyping related activities in the domain of printed circuit board (PCB) assembly. The focus of discussion is restricted to Surface Mount Technology (SMT) based processes only. In general, Virtual Prototyping enables the conceptualization, evaluation and validation of proposed ideas, plans and solutions. Using a virtual prototyping framework, cross functional evaluation and analysis can be facilitated where designers, manufacturing engineers, testing and other life-cycle team members can communicate effectively as well as identify and eliminate problems, which may arise later in the downstream manufacturing and testing activities.
A Quantitive Analysis on Virtual Reality-Based Computer Aided Design System Interfaces
Authors: Chu Chi-Cheng , Gadh Rajit
Published: June 2008

In this paper, a series of interface tests on interaction approach for the generation of geometric shape designs via multi-sensory user interface of a Virtual Reality (VR) based System is presented. The goal of these interface tests is to identify an effective user interface for VR based Computer-Aided Design (CAD) system. The intuitiveness of the VR based interaction approach arises from the use of natural hand movements/gestures, and voice commands that emulate the way in which human beings discuss geometric shapes in reality. The focus of this paper is on determining a set of effective interaction approaches by using the combinations of auditory, tactile, and visual sensory modalities to accomplish typical CAD tasks. In order to evaluate the proposed interaction approach, a prototypical VR-CAD system is implemented. A series of interface tests were performed on the prototypical systems to determine the relative efficiency of a set of potential interaction approach with respect to specific fundamental design tasks. The interface test and its results are presented in this paper.
Simulation of Flow-Induced Oscillations of a Rectangular Bluff Body in Incompressible, Turbulent Flow
Authors: Bunge Ulf , Gurr Andreas , Thiele Frank
Published: June 2008

The incompressible flow around a rectangular body with a length to height ratio of L/H = 2 and its flow–induced oscillatory behavior is numerically investigated at different Re–numbers in a range between 1 to 6 · 104. The body has one degree of freedom perpendicular to the mean–flow direction with a linear spring and linear damping. To compute the flow a finite–volume based Navier–Stokes CFD-code is used, which is enhanced by a finite–difference based algorithm to solve the vibration differential equation. Target is the numeric simulation of a incident flow velocity where resonance occurs and the exact determination of the physical mechanisms especially in the flowing medium. Particular substantial parameters of the total model, e.g. turbulence modeling, time step or grid, which exert influence on the quality of the simulation are examined. To achieve this aim simulations with steady and oscillating body are compared with experimental data and deviations are analyzed.
Effects of Sterilization Techniques and Culture Time on the Creep of Collagenous Ligament Analogues
Authors: Dickerson Darryl A. , Dee Kay C. , Livesay Glen A.
Published: June 2008

Every year, approximately 200,000 anterior cruciate ligament (ACL) injuries occur in the United States; of these cases, 60,000–75,000 patients undergo ACL reconstruction [1]. The ACL plays a critical role in knee stability; however, it possesses little inherent capacity for healing. Although reconstruction is often used in active patients, issues such as donor site morbidity and long term joint stability have motivated interest in tissue-engineered ligament analogues.
Age-Related Differences in the Biaxial Biomechanical Behavior of Human Abdominal Aorta
Authors: Vande Geest Jonathan P. , Sacks Michael S. , Vorp David A.
Published: June 2008

The biomechanical response of abdominal aortic tissue to uniaxial loading conditions has been reported previously [1]. This testing identified the uniaxial mechanical response of aortic tissue to specimens oriented in the longitudinal and circumferential directions, but did not provide significant evidence for the isotropy or anisotropy of this tissue. The information taken from uniaxial tensile testing is insufficient for the characterization of the multi-axial mechanical response of aortic tissue. In particular, the uniaxial response of a biological tissue in a given direction does not incorporate the effects of loading in an orthogonal direction. For these reasons, there exists a need for an enhanced description of the mechanical response of aortic tissue to loading in multiple planar directions. For the current investigation, biaxial tensile testing was performed on normal abdominal aortic tissue in order to gain insight into the anisotropy and age related differences of the biomechanical response of this tissue.
Tissue-Engineered Arteries Created by Directed Remodeling of Intact Arterial Segments
Authors: Nichol Jason W. , Clerin Valerie M. , Gooch Keith J.
Published: June 2008

There is a sizable unmet demand for effective small-diameter vascular prostheses for use in coronary bypass surgery. Currently, the best replacements for occluded arteries are autologous arteries, which have a cumulative patency rate of up to 93% after 5 years [1]. In spite of recent surgical advances the use of autologous arteries, such as the internal thoracic artery, is limited by the availability of donor arteries of appropriate length and diameter. Donor veins of appropriate dimensions are more readily available and frequently used despite substantially lower patency (45% after 5 years) [1]. Many have created tissue-engineered arteries that grossly resemble native vessels, but in animal studies, their performance was inferior to that of autologous veins with about half having decreased perfusion or loss of patency within 1 month [2] whereas human saphenous vein grafts have a patency of ∼90% at early time points and 81% after 1 year [3]).
Computational Modeling of Human Leukocyte
Authors: Marella Saikrishna , Udaykumar H. S.
Published: June 2008

Leukocytes (white blood cells) occupy only about 1/600th of blood by volume [1,2]. However, in view of the fact that leukocytes are larger and much stiffer than red blood cells, their presence is critical to the fluid mechanics of blood flow in the peripheral blood vessels, where the vessel diameters are comparable to those of the cells. These circulating cells must navigate through narrow micro-capillaries and recover to their undeformed spherical shape. Leukocytes act as the first line of defense in fighting disease. Leukocyte recruitment for this role involves a series of steps, including margination to vessel walls, rolling, adhesion to the endothelium, activation and locomotion and extravasation through the vessel wall to the tissue, which is afflicted by the trauma. Because the leukocyte is stiff and difficult to deform it can plug occluded micro-capillaries, leading to events such as ischemic stroke. Furthermore, leukocyte agglomeration and subsequent emolization can have serious consequences in patients under trauma, causing organ loss or even fatalities due to ischemia reperfusion injury. In these various scenarios, the rheological behavior, i.e. the physics of deformation and recovery of leukocytes under a wide variety of imposed flows, is essential.
The Effect of Bone Modulus on the Stress Distribution in a Dental Implant: A 3D Finite Element Analysis
Authors: Bozkaya Dinc¸er , Mu¨ftu¨ Sinan
Published: June 2008

The long-term success of dental implants depends, in part, on the stress distribution created in the bone, when the implant is loaded by biting forces. In this presentation, we present our findings on the stress distribution characteristics of a dental implant by varying bone mechanical properties surrounding the implant.
Mechanical Stress Patterns in the Human Proximal Tibial Growth Plate During the Stance Phase of Normal Gait
Authors: Lerner Amy L. , Gushue David L. , Gedbaw Emily A.
Published: June 2008

Since the mid 1800’s clinicians and researchers have considered the effect of mechanical stresses on bone growth and the development of growth disorders [1]. However, the specifics of this relationship remain poorly understood. Both clinical and experimental evidence support the concept that magnitude, frequency and duration of loads are critical in defining the response of cartilage to pressures [2, 3]. Yet, the range of physiologic pressures in the growth plate has not been identified, and most models of growing bones have considered single quasi-static loading conditions and/or elastic material models that can not accurately represent time dependence [4, 5]. It was the goal of this study to implement loading conditions representing an entire stance phase of gait in a two-dimensional model of the proximal tibia of a normal child. A poroelastic material model was used in order to identify the variations in growth plate pressures in both time and location, and investigate the potential for fluid flow within the growth plate.
Functional Evaluation of Soft Tissue Insertions to Bone
Authors: Raasch James B. , Livesay Glen A.
Published: June 2008

Soft tissue insertions into bone are of critical importance in transmitting forces from ligaments and tendons to bone, and thus are crucial in joint stability and musculoskeletal motion. Despite their importance, there exists no established experimental method for rigorously determining their function. Previous studies [1–3] have established the pull-out test as the standard method of evaluating the mechanical function of soft-tissue insertions, however, as this method tests response at a single orientation it may not capture the overall function of soft-tissue insertions.
Fatigue Crack Behavior and Fracture Toughness of Gamma Irradiated 1900H and GUR 1050 UHMWPE
Authors: Eberhardt Alan W. , Cole Jantzen C. , Lemons Jack E.
Published: June 2008

Gamma irradiation, oxidation and crosslinking of ultra-high molecular weight polyethylene (UHMWPE) may influence the material’s resistance to delamination in reciprocating sliding experiments and in knee simulators. It may also alter fracture toughness and fatigue crack propagation resistance. While 1900H components displayed less delamination wear as compared to machined GUR 415 [1], strength and ductility were reduced in aged, gamma irradiated, compression molded 1900H as compared to GUR 1050 [2]. The purpose of the present study was to determine the effects of gamma irradiation crosslinking, at different levels of irradiation, on the fatigue crack growth resistance and fracture toughness of 1900H and GUR 1050 UHMWPE. It was hypothesized that, for both resins, fatigue crack resistance and fracture toughness would decrease when gamma irradiation was applied, and that decreases would be dosage dependent. We further conjectured that the GUR 1050 resin would, overall, outperform the 1900H resin.
Biomechanical Comparison of Posterior and Transforaminal Interbody Fusion Constructs for the Degenerative Lumbar Spine
Authors: Lee Stan , Ghanayem Alexander , Hodges Scott , Voronov Leonard , Havey Robert , Patwardhan Avinash
Published: June 2008

Posterior lumbar interbody fusion (PLIF) is an established technique that allows circumferential fusion of lumbar spine through a single incision. A variation of PLIF called transforaminal lumbar interbody fusion (TLIF) uses a posterior approach to the spine but accesses the disc space via a path that runs through the far lateral portion of the vertebral foramen. TLIF provides the surgeon with a fusion procedure that reduces many of the risks and limitations associated with PLIF. Like PLIF, TLIF is easily enhanced when combined with posterolateral fusion (PLF) and instrumentation. TLIF offers an advantage in that it is usually done via a unilateral approach preserving the facet joint and the interlaminar surface on the contralateral side [1]. It minimizes soft tissue stripping and neural element retraction compared to PLIF, while providing a single-stage circumferential fusion. This study compared the biomechanical performance of these two constructs in flexion, extension, and lateral bending under physiologic compressive preloads.
Machining Process Monitoring and Control: The State–of–the–Art
Authors: Liang Steven Y. , Hecker Rogelio L. , Landers Robert G.
Published: June 2008

Automation at the process level for machining operations and machine tools has been a focus of research attention in both academia and industry alike for several decades. Research in this area has carried strong expectations in the context of increased productivity, improved part quality, reduced costs, and relaxed part design constraints. The basis for these expectations is two-fold. First, machining process automation, if exercised strategically and advantageously, can perform consistently for large batch production or flexibly for small batch jobs. Secondly, process automation can be set up to autonomously tune the machine parameters (feed, speed, depth of cut, etc.) in pursuit of desirable performance (tolerance, finish, cycle time, etc.), thereby bridging the gap between product design and process planning while reaching beyond the human operators’ capability. The success of manufacturing process automation hinges primarily on the effectiveness of process monitoring and control systems. This paper reviews the evolution and the state of the art of machining process monitoring and control technologies. Key issues to be presented include sensor techniques, control techniques, hardware availability, and implementation examples. Also to be reviewed are the benefits of the systems and the reasons for their delayed realization in many of today’s industrial application domains.
Laplace’s Equation, Genetic Algorithms, and Evolution
Authors: Tsourkas Philippos K. , Rubinsky Boris
Published: June 2008

With the advent of problems in genetics that are either too difficult or too dangerous to solve experimentally, it is important to have mathematical tools available so that these problems may be solved through modeling and computation. To this end we developed a mathematical experimentation procedure to simulate the evolution of a population of individuals. The procedure employs genetic algorithm methodology to study a ‘species’ that is comprised of solutions to the Laplace equation. The algorithm is applied to the study of a particularly significant and controversial problem: The release of genetically engineered organism in the wild.
An Inverse Method to Measure the Complex Dynamic Moduli of Elastomers
Authors: Berthelot Yves H. , Wu Lei
Published: June 2008

The dynamic moduli of elastomers are estimated from measurements of the surface velocity of a 3D sample. The measured values are matched with predictions from a finite element model in which the material properties are adjustable parameters. The sensitivity of the inversion technique to the locations of the measurements is discussed. Numerical simulations indicate that the method might be used to determine the moduli of two isotropic layers bonded together. Results also indicate the possibility of detecting the presence of a large defect in the sample.
Enhancement of Reconstruction Accuracy of the HELS Method
Authors: Semenova Tatiana , Wu Sean F.
Published: June 2008

The validity of the HELS method (Wu, 2000) for reconstructing the acoustic pressure field inside the minimum circle that encloses an arbitrary object is examined. Results show that the HELS solutions are approximate and the corresponding matrix equation is ill conditioned in general for back propagation of the acoustic field. Accordingly, the further the reconstruction point moves inside the minimum circle, the worse the reconstruction accuracy becomes. To overcome this difficulty new strategy for sensor placement is proposed. This strategy together with a constrained minimization are shown to yield satisfactory reconstruction inside the minimum circle. The same procedures can be extended to three-dimensional problems.
A Continuum Model of Thrombus Growth and Flow Impingement
Authors: Wootton David M.
Published: June 2008

A species transport model of thrombosis is developed, which includes effects of thrombus impingement on the flow and finite platelet size. The model is implemented in commercial CFD package for easy transfer. Preliminary calculations, neglecting platelet activation kinetics, are consistent with experiments, and model the deflection of flow around the growing thrombus.
Numerical Simulation of Vortex Shedding in Tube Arrays
Authors: Sweeney C. , Meskell C.
Published: June 2008

Vortex shedding may occur in tube arrays, resulting in strong excitation forces at discrete frequencies. In the past the Strouhal numbers governing vortex shedding in these systems were determined experimentally. This paper presents a method of numerical simulation for the unsteady flow through a rigid normal triangular tube array and hence provides a method of determining both the frequency of vortex shedding and the magnitude of the fluid forces acting on the tubes. The technique used is based on a discrete vortex method similar to the cloud-in-cell approach which has been applied to flow problems for small numbers of cylinders. However, in the current implementation the flow velocity calculation is carried out on an unstructured grid using a finite element discretization. Thus, the complex geometry associated with a tube array can be easily accomodated. The method, referred to as the “Cloud-in-element” method, is validated for the standard case of flow over a single cylinder and then applied to flow through a normal triangular array with a pitch diameter of 1.6. The Reynolds number is 2200. The Stouhal number obtained from the numerical simulation is 1.27, which is within 6% of the value available in the literature. Qualitatively, the vortex shedding pattern obtained is in agreement with published flow visualization.
Improved Crashworthy Aircraft Seat Design
Authors: Kasturi Kash , Kwok Peter
Published: June 2008

An innovative transport aircraft passenger seat concept for superior occupant protection, meeting all structural requirements used in typical seat designs was developed. This was accomplished with the use of new energy-absorbing structural members and precise control of seat deformation characteristics. Advanced dynamic finite element modeling technique was utilized to analyze the integrated design of the seat, occupants, restraints and energy absorbing elements. Results from certification tests on an existing seat design were used to validate the analytical model. Verification studies have shown good correlation between the analytical simulations and the test data. In addition, further improvements to occupant protection of this new aircraft seat design were accomplished by incorporating the seat back tilt mechanism coupled with the use of shoulder belt. The seat back tilt mechanism utilizes similar energy-absorption concept and provides additional energy absorption while being pulled forward by the shoulder belt.
Effect of Gravity on a Free-Free Fluid-Structure System
Authors: Schotte´ Jean-Se´bastien , Ohayon Roger
Published: June 2008

In this paper, we propose a symmetric variational formulation for the eigenmode computation of a free-free elastic tank partially filled with an incompressible inviscid liquid in presence of a gravity field. The originality of this model is to take into account the strong coupling between the sloshing of the liquid free surface and the hydroelastic deformations of the tank. We will show that this allows the rigid body modes of the system to be predicted correctly.
Development of a Laser-Based Micro-Drilling Center
Authors: Jackson Mark J. , Mills Benjamin
Published: June 2008

The micro-machining of components for use in electronic and mechanical devices is a well-established science. Techniques have advanced sufficiently for the realisation of an increasingly diverse range of microstructures that can be used as components for micro-systems. Demand for micro-components has necessitated the need to employ alternative manufacturing techniques so that a wider range of materials such as polymers, metals, ceramics and composites can be used in microstructures. Current research in this area is focused on the machining of engineering materials at the micro-level through the use of nanosecond, pulsed lasers. The use of nanosecond, pulsed lasers provides surface intensities of the order of 1012W/cm2, enabling rapid vaporisation of the material at the surface of the workpiece. This paper discusses the challenges presented by laser micro drilling of M2 tool steels.
Integrated Piezoelectric Linear Motor for Vehicle Applications
Authors: Vaughan Mark , Leo Donald J.
Published: June 2008

The focus of this research was to create a linear motor that could easily be packaged and still perform the same task of the current DC motor linear device. An incremental linear motor design was decided upon, for its flexibility in which the motor can be designed. To replace the current motor it was necessary to develop a high force, high speed incremental linear motor. To accomplish this task, piezoelectric actuators were utilized to drive the motor due their fast response times and high force capabilities. The desired overall objectives of the research is to create an incremental linear motor with the capability of moving loads up to one hundred pounds and produce a velocity well over one inch per second. To aid the design process a lumped parameter model was created to simulate the motor’s performance for any design parameter. Discrepancies occurred between the model and the actual motor performance for loads above 9.1 kilograms (20 pounds). The resulting model, however, was able to produce a good approximation of the motor’s performance for the unloaded and lightly loaded cases. The incremental linear motor produced a velocity of 4.9 mm/sec (0.2 in/sec) at a drive frequency of 50 Hz. The velocity of the motor was limited by the drive frequency that the amplifiers could produce. The motor was found to produce a stall load of 17 kilograms (38 pounds). The stall load of the design was severely limited by clearance losses.
Generalizing the Theory of Microdialysis
Authors: Banerjee Rupak K. , Bungay Peter M. , Sarntinoranont Malisa , Chippada Srinivas
Published: June 2008

The efficiency of sampling or delivering solutes (analytes) by in vivo microdialysis is influenced by the diffusive permeabilities of the probe and the tissue in which the probe is implanted. In tissue, processes removing the analyte from the extracellular space are as important as diffusion in determining permeability. In addition to diffusion, analyte permeation through these media may be augmented or diminished by bulk fluid movement (transmembrane and interstitial convection). Within the perfusate, the dominant process is axial convection. Both diffusive and convective determinants of probe efficiency may be influenced by probe geometry (Figure 1; longitudinal cross-sectional view). The main geometric parameters are the probe membrane length and radii, but inner cannula geometry can also be an appreciable factor. The objective of this study is to generalize the mathematical description of microdialysis. The treatment extends in several ways previous mathematical models (Bungay et al. [1]; Morrison et al. [2]; Morrison et al. [3]; Wallgren et al. [4]). In addition to removing some simplifications and approximations and adding convective transport, the revised theory is applicable to low-molecular-weight lipophilic, as well as hydrophilic solutes. This is achieved by incorporating transcellular solute movement as a pathway paralleling interstitial diffusion. This change accompanies employing the combined intracellular and extracellular volumes, rather than the interstitial volume, as the basis for solute mass balances.
Aeroelastic Analysis of Oscillatory Blowing Control of the Airfoil’s Flutter at Large Attack Angle
Authors: Yan Jin , Xin Yuan
Published: June 2008

It is known that oscillatory blowing on the back of an airfoil can delay the flow separation and the stall. The purpose of the present paper is to apply the oscillatory blowing technique to the control of the airfoil’s flutter. High accuracy, high solution fluid-structure coupling numerical method is used in the study. The numerical results show that the steady blowing will weaken the flutter, but at the same time the excess blowing will make the lift coefficient to drop. The best blowing velocity can be found by the present numerical method. The influence of the frequency and the amplitude of the oscillatory blowing on the airfoil’s vibration is studied in the paper. The numerical results show that the oscillatory blowing is more efficient in the cases of flutter than steady blowing.
Transient Response Study on Rolling Effectiveness of Multiple Control Surfaces
Authors: Tang Deman , Li Aiqin , Dowell Earl H.
Published: June 2008

In the present paper, a transient response study of the effectiveness of trailing and leading edge control surfaces has been made for a rolling wing-fuselage model. An experimental model and wind tunnel test are used to assess the theoretical results. The theoretical model includes the inherently nonlinear dry friction damping moment that is present between the spindle support and the experimental aeroelastic wing model. The roll trim equation of motion and the appropriate aeroelastic equations are solved for different combinations of leading and trailing edge control surface rotations using a reduced order aerodynamic model based upon the fluid eigenmodes of three dimensional vortex lattice aerodynamic theory. The present paper provides new insights into the transient dynamic behavior and design of an adaptive aeroelastic wing using trailing and leading edge control surfaces.
Quantitative Assessment of Glenohumeral Joint Forces in Positions of Overhead Activities: Effects of Shoulder Arthroplasty
Authors: Lee Thay Q. , Schamblin Mark , Yang Bruce Y. , McGarry Michelle H. , Gupta Ranjan
Published: June 2008

Glenohumeral arthroplasty as well as hemiarthroplasty, although providing adequate pain relief, has not shared in the success of similar joint replacement procedures such as total knee arthroplasty or total hip arthroplasty. Short comings of this procedure include a decreased range of motion postoperatively as well as increased incidents of glenoid component loosening in total shoulder procedures. This is especially a problem in the end ranges of motion where eccentric loading of the glenoid component are thought to occur. The purpose of this study was to quantify the glenohumeral joint forces before and after bipolar shoulder hemiarthroplasty and total shoulder arthroplasty for positions simulating overhead activities and commonly relied upon by the wheelchair dependent individual.
Extraction of Flow Information in Choriocapillaris in Human Eyes From ICG Dye Angiography Images
Authors: Zhu L. , He Q. , von Kerczek C. H. , Topoleski L. D. T. , Flower R. W.
Published: June 2008

Indocyanine green (ICG) dye angiography has been used by ophthalmologists as a useful tool for routine examination of the vasculature of the choroid in human eyes. ICG dye angiography is performed by venous injecting of ICG dye, which is delivered to different vascular structures in the eyes at different times. A multi-spectral fundus camera is used to take the dye intensity images of the eye at a speed of thirty images per second. In this study, a new approach is developed to extract information of velocity distribution in the choriocapillaris and its feeding blood vessels from the ICG dye angiograms. The ICG dye intensity rise and decay curves are constructed from the ICG dye images at each image pixel location in the choriocapillaris. It is shown that the magnitude of the local velocity in the choriocapillaris is proportional to the transient of the ICG dye intensity curve. The approach allows the determination of the absolute value of the velocity in the choriocapillaris and is calibrated by the image data at two axial locations of a straight blood vessel of uniform cross-section area. The velocity image of the entire choriocapillaris is then constructed. This approach could be used in clinical applications for diagnostic purposes since it provides detailed quantified flow information in human eyes.
Shear Stress Effect on the Production of Nitric Oxide in Cultured Rat Aorta Endothelial Cells
Authors: Ye Jianfeng , Chen Baoguo , Xu Lisa X.
Published: June 2008

Atherosclerotic lesions tend to develop in regions where there are separations from unidirectional laminar blood flow, typically near branches, bifurcations, regions of arterial narrowing, and curvatures in the arteries (1, 2). Obviously, homodynamic forces play a key role in atherosclerosis. Studies also indicate that vascular endothelium function disturbance, especially impairment of endothelium dependent vasodilation, is involved (3). Shear stress affects endothelial cells in many ways, such as cytoskeletal rearrangement, decrease of intracellular pH, release of PGI2 and some growth factors (PDGF, FGF, ECGF, TGF-b, etc), activation of IP3 and mitogen-activated protein kinases, and the significant increase in the production of nitric oxide (1,2,4,5). As an important function factor of vascular endothelial cells, nitric oxide (NO) is closely related to the endothelial dysfunction and atherosclerosis (6). Endothelial derived nitric oxide involves in many events in the vasculature, including vasodilation, inhibition of platelet aggregation, adhesion molecule expression, and vascular smooth muscle proliferation, which are directly or indirectly related to atherosclerosis. Endothelial cells release NO more potently in response to increased shear stress than to agonists that raise intracellular free calcium concentration [Ca2+]i. Studies have indicated that NO production increases with a calcium/CaM dependent manner in the first few minutes after exposed to shear stress, followed by a sustained NO production that occurs more than 30min which is Ca2+ independent (7). The activation of eNOS by shear stress, which modulated by Ca/CaM, G protein, tyrosine kinase phosphorylation and eNOS gene expression, is responsible for the increase of NO production (8). However, the contribution of extracellular calcium to the production of NO is somewhat contradictory.
Design of a Microfluidic System for 3D Culture of Osteocytes In Vitro
Authors: Takai Erica , Hung Clark T. , Tucay Aurea , Djukic Djordje , Linde Mary L. , Costa Kevin D. , Yardley James T. , Guo X. Edward
Published: June 2008

Bone adapts to its mechanical environment so that its form follows function, a mechanism known as Wolff’s law, or bone adaptation. Although the basic concepts of Wolff’s law have been generally accepted, the regulatory signals and the underlying cellular and molecular pathways, which mediate this adaptive process, are unknown. Failure of normal bone adaptation plays a significant role in the etiology of metabolic bone diseases such as osteoporosis and osteopetrosis, bone loss in space flight and failure of total joint replacements. During the past three decades, there have been extensive in vitro studies addressing mechano-signal transduction mechanisms in bone cells including osteoblasts, osteocytes, and osteoclasts [1–8].
Progress in Railroad Freight Car Engineering
Authors: Punwani Swamidas K.
Published: June 2008

Every year the Rail Transportation Division (RTD), American Society of Mechanical Engineers (ASME) conducts a survey to document progress in the design, construction and use of freight cars and components. This paper describes the new developments. Some information was obtained from web sites. The industry continued to focus on the evolution of freight equipment in 2002 by adding flexibility and versatility to designs developed in the recent past. Due to a slow down in new car building fewer responses were received.
LRV Compression Loads: Statistical Data and Recommendations
Authors: Lewalski Z. M. , Lewalski Elizabeth Eva
Published: June 2008

Carbody compression resistance is a major LRV safety feature in head-on collisions. Regrettably, one of the difficulties in writing LRV specifications has been establishing credible values for the design compression loads that the carbody shall demonstrate to resist. One reason for this difficulty is that setting compression loads involves judgment and therefore is to a great degree subjective. The other is that vehicle engineers have been setting design compression loads in relative isolation from each other, without the benefit of a broader discussion among them. This paper will attempt to reconcile the various positions and, based on statistical data, will recommend median values for compression loads as a function of carset kinetic energy.
Low Cost Microbolometer Development Using Commercially Available CMOS Foundry Processes
Authors: Dang Khoa V. , Pouliquen Philippe , Grenn Michael , Andreou Andreas , Blase Paul , Phu Sanh
Published: June 2008

We have demonstrated the monolithic fabrication of uncooled microbolometer Focal Plane Arrays (FPAs) for infrared imaging applications using available CMOS, BiCMOS foundry processing and micromachining techniques which trade higher performance with potentially much higher yield and lower production costs. Past and current efforts have exclusively focused on using the commercial silicon foundries for the Readout Integrated Circuits (ROICs) fabrication, and then the microbolometer detector bridges are fabricated on top of the ROICs using processes that involve many complex growth layers and etching steps. These current approaches require specialized microbolometer fabrication facilities and foundries to be built and maintained. We have demonstrated methods to fabricate inexpensive, reasonable performance uncooled microbolometer FPAs using commercially available silicon foundries. To be truly cost effective, we are using the commercial foundries to fabricate the microbolometer FPAs. To release or suspend the bolometer structures, we have used a simple post-foundry maskless anisostropic or isotropic wet/dry etch. We have fabricated a prototype 13×14 uncooled microbolometer FPA using the commercial AMI 1.5um CMOS process as well as a 38×38 microbolometer array using the AMI 0.5um CMOS process. Discussions of the microbolometer circuit designs, MEMS micromachining techniques, and test results will be presented.
Cavitation at Micro-Scale in MEMS Fluid Machinery
Authors: Pennathur S. , Peles Y. , Epstein A. H.
Published: June 2008

Cavitation has long been a concern in the engineering of fluid machinery. The state of the art in MEMS is now such that micro-machines are being designed and built which, by conventional macro-world criteria, can operate in cavitating regimes. Specifically, cavitation in 900-micron-chord cascades characteristic of micro-centrifugal pumps was investigated through analysis and experiment for working fluids of water and ethanol. The primary finding was that cavitation in these micro-devices exhibited static and dynamic behavior very similar to that expected in large scale flows. Furthermore, conventional cavitation models coupled to 2D and 3D CFD simulations matched the micro-scale data well in predicting the onset of cavitation and the length of the cavitation zones. Also, no mechanical damage from cavitation was found. This implies that vacitation in micro-machines will offer no unusual surprises to device designers.
Decentralized Vibration Control in a Launch Vehicle Payload Fairing
Authors: Frampton Kenneth D.
Published: June 2008

The vibro-acoustic environment inside a launch vehicle payload fairing is extremely violent resulting in excessive development costs for satellites and other payloads. The development of smart structures and active noise and vibration control technologies promised to revolutionize the design, construction and, most importantly, the acoustic environment within these fairings. However, the early promise of these technologies has not been realized in such large-scale systems primarily because of the excessive complexity, cost and weight associated with centralized control systems. Now, recent developments in MEMS sensors and actuators, along with networked embedded processor technology, have opened new research avenues in decentralized controls based on networked embedded systems. This work describes the development and comparison of decentralized control systems that utilize this new control paradigm. The controllers are hosted on numerous nodes, possessing limited computational capability, sensors and actuators. Each of these nodes is also capable of communicating with other nodes via a wired or wireless network. The constraints associated with networked embedded systems control that the control systems be relatively simple computationally, scalable and robust to failures. Simulations were conducted that demonstrate the ability of such a control architecture to attenuate specific structural modes.
Aeroacoustical Coupling and Its Structural Effects on a PWR Steam Line: Part 1 — Numerical Investigations of Flow Acoustic Coupling in a Subsonic Flow Past a Shallow Cavity
Authors: Lafon Philippe , Lambert Christophe , Devos Jean-Paul , Caillaud Se´bastien
Published: June 2008

A pure tone phenomenon has been observed at 460 Hz in a PWR steam line. The acoustical energy has been identified to be generated in an open gate valve and to be of cavity noise type. The objective here is to understand the flow acoustic coupling in the cavity and in the duct. Both experimental and numerical investigation ways are used. The flow acoustic phenomena are modeled by computing the Euler equations. Two different computations are carried out: in the first one, a pure Euler modeling is used, in the second one, a boundary layer obtained from experimental data is introduced in the computation in order to have a realistic flow profile upstream the cavity. In the first computation, the acoustic excitation due to the cavity is qualitatively retrieved but the frequency is too high compared to the experimental one and no cavity duct coupling is detected. In the second computation, the frequency of the cavity oscillation is very close both the theoretical one and the experimental one. As it is also very close the frequency of the first transverse mode of the duct, the two modes of oscillation (the cavity one and the duct one) are coupled.
Study on Damage Progression Process for Plain-Woven Carbon Fabric Composites Under Cyclic Loading
Authors: Nishikawa Y. , Okobo K. , Fujii T.
Published: June 2008

In this study, the damage progression process for plain-woven carbon fabric composites (PW-CFCs) under cyclic loading was investigated. Under cyclic loading, the damage progression was estimated intermittently by using the thermo-elastic damage analysis (TDA) method. Crack density for each layer of the specimen was also estimated at several stages of fatigue. It was found from these results that the damage progression process was divided into three stages. In the first stage, especially, the damage accumulation occurred independently in the PW-CFC specimen and progressed easily along the transverse fiber bundles. All experimental results showed that the damage progression in the first fatigue stage was explained by considering damage-units (a unit area of damage progression and accumulation). Based on the percolation theory, the damage progression for PW-CFC under cyclic loading can be characterized by re-generating the distribution pattern of damage-units.
Application of the Electronic Speckle Pattern Interferometry (ESPI) Technique for the Localisation Analysis of Damage Development in Composites
Authors: Bouquet Pascal J. P. , Cardon Albert H.
Published: June 2008

The analysis of the long-term behaviour of polymer matrix composites has to be performed for their stiffness evolution and for their strength changes. Long fiber reinforced polymer matrix composites exhibit an anisotropic viscoelastic-viscoplastic behaviour. The non-linear viscoelastic constitutive equations proposed by R. Schapery [1], with a viscoplastic correction are able to analyse the long-term stiffness evolution on the basis of some short-term creep and creep-recovery tests. For the strength analysis it is possible to consider some delayed failure approach as the end of a viscoelastic-viscoplastic behaviour. The experimental follow-up of the creep evolution till rupture needs a full field technique in order to have a complete view of the strain field and the evolution of this field where the damage initiation and development transforms the homogeneous strain distribution in an heterogeneous one. The ESPI technique shows clearly the location of the damage initiation and allows us to follow the damage development. Examples of the ESPI technique on graphite epoxy specimen will be presented and the results in relation to the delayed failure analysis will be discussed.