bluuebunny/crossref_metadata_2025 huggingface dataset:
A Neuro-Muscular Elasto-Dynamic Model of the Human Arm
Authors: Moody Cody B. , Barhorst Alan A. , Schovanec Lawrence
Published: May 2008

In this paper we develop a neuro-muscular elasto-dynamic model of the human arm. The generality of the approach provides a method for relating effects of neural and muscular control on stress development in skeletal structures. The humerus is pinned parallel to the body and allowed to rotate in the plane. The radius and ulna are free to move in the sagittal plane. The bones are modeled as elastic elements, allowing large transverse deflections and elongations. Standard Hill-type models of the musculotendon actuators are used to generate the joint torques. Simulations are presented that correspond to both open and closed loop neural stimulus, and stresses and strains that result from both types of control are compared.
Human Response to Dynamic Rollover Conditions
Authors: Bish Jack , Honikman Terence , Sigel Jason , Nash Carl , Friedman Donald
Published: May 2008

To date, human responses in motor vehicle rollover accidents have been studied through the use of Hybrid III dummies in dolly vehicle rollover tests, quasi-static spit tests where the vehicle and occupant are rotated slowly about the rotation axis of the spit fixture, computer simulations and vehicle drop tests. To demonstrate human responses to dynamic rollover conditions more accurately we designed and built a fixture to accommodate a passenger compartment in a hoop structure that rotates as it translates. The rotational axis of the hoop structure is offset from the rotational axis of the passenger compartment to replicate vehicle center of gravity motion seen in dolly rollover tests. Testing showed the difference in restraint behavior depending upon whether the occupant was seated on the near (initially leading) or far side. It demonstrated that human and Hybrid III dummy neck response is very different. The human test subject received no injuries from diving into the roof of the passenger compartment even though this is the predicted injury mechanism reported in several technical papers.
The Effects of Refreezing on the Tensile Properties of the Medial Collateral Ligament-Bone Complex: A Rabbit Model
Authors: Moon Daniel K. , Gabriel Mary T. , Abramowitch Steven D. , Takakura Yoshiyuki , Woo Savio L.-Y.
Published: May 2008

Biomechanical tests of soft tissues, especially those from human cadavers, are generally done after a period of postmortem storage by freezing. In some instances, specimen preparation and testing can be complex and can take place over several days, thus necessitating an additional period of frozen storage before biomechanical evaluation is completed. Studies have been done in the past, which investigated the effects of postmortem freezing on the tensile properties of ligament-bone complexes (Viidik and Lewin 1966; Noyes and Grood 1976; Dorlot 1980; Barad 1982; Nikolaou 1986; Woo, Orlando et al. 1986). It has been shown in our laboratory that careful postmortem freezing for up to three months did not significantly change the mechanical properties of the ligament midsubstance and the cyclic stress relaxation behavior and the structural properties of the ligament-bone complex, but the area of hysteresis was significantly reduced in the stored specimens for the first few cycles of cyclic stress relaxation (Woo, Orlando et al. 1986). Hence, it is important to ensure that an additional freezing and thawing cycle will not further change the tensile properties of these tissues. Therefore, the objective of this study was to evaluate the effects of freezing and thawing twice at 20°C on the structural and viscoelastic properties of femur-medial collateral ligament-tibia complex (FMTC) in a rabbit model.
Development and Validation of a Finite Element Model of the Pelvis
Authors: Anderson Andrew E. , Peters Christopher L. , Tuttle Benjamin D. , Weiss Jeffrey A.
Published: May 2008

An improved understanding of the stress distribution in and around the hip joint may provide important information regarding the relationship between altered pelvic and acetabular geometry and development of hip osteoarthritis, as well as point to improved diagnostic methods and analysis of surgical treatment. It is very difficult to accurately assess how changes in pelvic geometry affect the stress and strain distribution of the joint in an experimental setting. The finite element (FE) method provides an alternative approach for study of hip joint mechanics. Although FE models of the pelvis have been developed, validation by direct comparison with subject-specific experimental measurements has not been performed. In addition, previous models have utilized over-simplified bone geometry and homogeneous material properties. The objectives of this study were to 1) develop and validate a FE model of the pelvis using subject-specific measurements of bone geometry as well as location-dependent cortical thickness and trabecular bone elastic modulus, and 2) assess the sensitivity of the subject-specific FE model to changes in material properties and cortical thickness.
Occupant Protection and Standup Forklift (Lift Truck) Dynamics
Authors: Harris Gerald F. , DeRosia John
Published: May 2008

This paper investigates dynamic standing postural stability during standup forklift operation through a series of live subject tests to determine the sensitivity to loss of stability and falling. Through a set of controlled tests, the tolerance to accelerations in the lateral, oblique, and longitudinal orientations is determined. The levels of acceleration causing loss of balance are in close agreement with earlier studies and support the use of a door in the case of a standup forklift and the use of a control corridor in the case of a pallet jack (walkie-rider) during routine operation.
Large Deformation of Biological Cells by Optical Tweezers
Authors: Suresh S. , Lim C. T. , Dao M.
Published: May 2008

The chemical and biological functions of living cells are known to be influenced strongly by mechanical forces and deformation, and the ability of cells to detect and support forces, in turn, is also affected by chemical and biological factors. Furthermore, the progression of a number of inherited and infectious diseases have also been identified to have a strong correlation with the mechanical deformation characteristics of biological cells. Consequently, the deformation characteristics of whole cells and cell membranes have long been investigated using a variety of experimental methods, such as the micropipette aspiration technique, and by computational modeling (see, for example, refs. [1, 2]). Recent advances in experimental techniques capable of probing mechanical forces and displacements to a resolution of picoNewton and nanometer, respectively, have facilitated use of mechanical test methods for living cells whereby precise measurements of response under different stress states could be investigated.
Contact Stress in a Gerotor Pump
Authors: Gamez-Montero P. Javier , Codina Esteve
Published: May 2008

The aim of the first part of this paper is to reach the optimum design parameters of a gear set when it works as part of an internal gear pump type gerotor. The performance of the gear teeth and the whole gear set are evaluated through analytical studies to obtain the maximum contact stress in gear teethe and the volumetric characteristics. Several gear sets have been examined and the results are presented. The aim of the second part of the this paper is to documents a better understanding of the performance of a crankshaft mounted gerotor pump for IC engines lubrication. Modeling, simulation and experimental work have been examined for a specific unit. A preliminary 2D simulation is carried out by using the Finite Element Method (FEX) to calculate the maximum contact stress. At the testing phase, a prototype model of the gear set provides the maximum contact stress on a pair of teeth by using photoelasticity measurement techniques. The results are exposed and discussed and possible alterations are proposed.
Model of Piezoelectric Power Harvesting Beam
Authors: Sodano Henry A. , Park Gyuhae , Leo Donald J. , Inman Daniel J.
Published: May 2008

Piezoelectric materials can be use as mechanisms to transfer mechanical energy, usually ambient vibration into electrical energy ahtat can be stored and used to power other devices. With the recent advances in wireless and MEMS technology, sensors can be places almost anywhere necessary. Since these devices are devices are wireless it becomes necessary that they have their own power supply. This power supply in most cases is the conventional bettery, however problems can occur when using batteries bacause of their finite life span. When the battery is extinguished of all its power, the sensor must be retrieved and the battery changed. Because wireless sensors are developed so that they can be placed in remote locations such as structural sensors on a bridge or GPS tracking devices on animals in the wild, obtaining the sensor simply to replace the battery can become a very expensive task. Therefore, if a method of obtaining the untapped energy surrounding these sensors was implemented,significant life could be added to the power supply. One method is to use piezoelectric materials to obtain energy lost due to vibrations of the test specimen. This captured energy could then be used to prolong the life of the power supply or in the ideal case provide endless energy for the sensors lifespan. The goal of this study is to develop a model of the piezoelectric power harvesting device. This model would simplify the design procedure necessary for determining the approapriate size and vibration levels necessary for sufficient energy to be produced and supplied to the electronics devices. An experimental verification of the model is also performed to ensure its accuracy.
Effective Test Procedures for Evaluating Force Characteristics of Magneto-Rheological Dampers
Authors: Ahmadian Mehdi , Poynor James C.
Published: May 2008

This paper will provide a new test procedure for determining the force characteristics of magneto rheological (MR) dampers that are commonly used for vehicle suspensions. Force characteristics of a damper, in this case, refers to establishing the amount of force that the damper can provide at different relative velocities across the two ends of the damper, Force characteristics of a damper, which are commonly presented as a plot of force versus relative velocity—commonly known as force-velocity curve—are established in a shock (or damper) dynamometer in which one end of the damper is kept fixed and the other end is moved in a cyclical manner at a prescribed displacement and frequency. The peak damper force at each velocity is measured and plotted as discrete data points versus relative velocity across the damper. This is a well-understood and commonly used procedure for passive shock absorbers or dampers. For magneto rheological dampers, however, our study shows that such procedures do not necessarily provide an accurate assessment of the force characteristics of MR dampers in all damping conditions. The damping condition of MR dampers can be changed by a small amount of electrical current that can be provided to the damper. The inaccuracies are mainly due to the changing dynamics of the MR fluid inside the damper at different damping conditions. This paper will provide the test results for a MR damper, using the new and the conventional test procedures. The test results indicate that the use of the new test procedure will procedure will allow for an accurate representation of the MR damper force at all velocities, within the range of the currents that the damper is designed for.
Biomechanical Benefits of Crosslink Augmentation in Spinal Discs
Authors: Hedman Thomas P. , Chuang Shih-Youeng , Syed Baber , Gray Dean
Published: May 2008

This study involved an investigation into the effect of non-toxic crosslink augmentation on spinal discs on disc durability and joint stability. Non-destructive indentation techniques were developed to quantify annulus fibrosis material property degradation resulting from non-traumatic cyclic fatigue. Joint stability was assessed using two different natural zone measures. A non-toxic crosslinking reagent formulation reduced fatigue-induced viscoelastic relaxation by two- to three-fold compared to controls. The same treatment was found to produce a four-fold reduction of instability scores. Stabilization was observed to be greater in the more mechanically unstable discs.
Synthesis and Characterization of MgB2 Bulk Superconductors With Enhanced Properties by Means of Silver Doping
Authors: Kumar D. , Yarmolenko S. , Waters C. , Sankar J.
Published: May 2008

Ag-doped MgB2 bulk superconductors have been prepared using a standard solid state processing. The addition of Ag to MgB2 powders during the sintering process has been found to result in an important advantage, namely, the prevention/reduction of loss of Mg, a problem most commonly observed in the sintering of MgB2 bulk samples at elevated temperature and ambient pressures. The Ag-doped MgB2 sample has a distinct superconducting transition temperature around 39 K, while the undoped MgB2 undergoes only a very feeble transition to a diamagnetic superconducting state at around 39 K. The normal conducting silver regions in the MgB2 matrix acts as pinning centers resulting in the realization of high critical currents in the presence of magnetic fields.
Non-Contact Area Measurement Techniques for Cross Sectional Properties of Soft Tissues
Authors: Bose Dipan , Kerrigan Jason R. , Ivarsson Johan , Madeley N. Jane , Millington Steve A. , Bhalla Kavi S. , Crandall Jeff R.
Published: May 2008

In this study, a non-contact optical three-dimensional digitization technique is described to account for area measurement problems related to soft tissue. The technique is used to generate digitized models of human knee ligaments (collateral and cruciate ligament bundles). Cross-sectional area of knee ligaments is determined by applying Green’s theorem on data obtained from the digitized models. The surface concavity features of different ligaments shown in this study signify the extent of approximation done by projection based methods. The study also reports the variation in cross-sectional shape of a ligament along its long axis, indicating the importance of deciding the appropriate cross section for stress calculation measurements.
Hybrid Ammonia Water Absorption System of Small and Medium Capacity
Authors: Chiriac Florea , Gavriliuc Robert , Dumitrescu Rodica , Ilie Anica , Piˆrvu Cristina
Published: May 2008

The paper presents an absorption system with compact heat exchangers (micro-channels), working with ammonia water solution, driven by either solar or electrical energy. The construction of the solar panels includes heat pipes, and they are able to provide hot water with a maximum temperature of 130°C. The cooling capacity of the system ranges from 5 to 10 kW. The system is designed for comfort the technological air conditioning, providing inside air temperatures in the range of 10°C to 20°C. The project promotes ammonia as an ecological and natural refrigerant and aims to experimentally evaluate the thermal performances of each component of the system (condenser, evaporator, absorber and vapor generator) and of the entire system. The next step consists in a theoretical versus experimental comparison of data. The thermal performances refer to heat transfer coefficients in micro-channels on water ammonia side, as well as on the airside, and to the performance coefficient for various working conditions.
Quantum Dots and FRET-Nanobeads for Probing Genes, Proteins, and Drug Targets in Single Cells
Authors: Agrawal Amit , Gao Xiaohu , Nitin Nitin , Bao Gang , Nie Shuming
Published: May 2008

Quantum dots are tiny light-emitting particles on the length scale of 2–10 nm, and FRET-nanobeads for fluorophore-embedded nanoparticles on the length scale of 40–200 nm based on the phenomenon of fluorescence resonance energy transfer (FRET). These materials are emerging as a new class of biological labels with properties and applications that are not available with traditional organic dyes and fluorescent proteins. In this ASME contribution, we report new developments in using semiconductor quantum dots for quantitative imaging and spectroscopy of single cancer cells. We also show results from intracellular staining of actin filaments using FRET-nanobeads. These results raise new possibilities in disease diagnostics, drug and biochemical discovery, cancer imaging, molecular profiling, and disease staging.
Numerical Simulation of Electromagnetically Driven Flow in the Weld Pool During Arc Welding
Authors: Kumar A. , DebRoy T.
Published: May 2008

The electromagnetic force results from the interaction between the current flow and the induced magnetic field in the weldment. Comprehensive three-dimensional calculations of current flow and induced magnetic field are needed for accurate determination of the electromagnetic force. In the literature, several simplifying analytical expressions for the electromagnetic force have been suggested and widely used without any critical evaluation of their intrinsic merit, since accurate numerical calculations were difficult in the past because of lack of fast computers. With the advances in computational hardware and software, it is now possible to do relatively complex calculations that were much more difficult to perform just a few decades ago. The objective of the present investigation is to propose a mathematical model to numerically solve the electromagnetic force field in the wildment and determine the effect of commonly used simplifications on the accuracy of the calculated electromagnetic force field and weld pool temperature and velocity fields. A numerical model has been developed to accurately calculate the current density and magnetic flux fields and the resulting electromagnetic force field in three dimensions in the entire weldment. The computed electromagnetic force field was used in a 3-D heat transfer and fluid flow model to calculate the temperature and velocity distributions in the weld pool. The fusion zone geometry was experimentally measured for different current, voltage and arc power distribution. The agreements between the calculated and experimental FZ geometries indicate that the proposed numerical model gives accurate electromagnetic force distribution inside the workpiece.
Investigation of Microcrack Growth in [0/90]s Composite Laminates
Authors: Verges Melody A. , Schilling Paul J. , Herrington Paul D. , Tatiparthi Arun K.
Published: May 2008

Techniques such as optical microscopy and X-radiography have provided useful information regarding damage in composite laminates, particular in therms of microcracking behavior in individual plies. This focuses on the investigation of microcracking and damage evolution in loaded composite laminates via X-ray computed microtomography. The main advantage in the use of such a technique is that damage within the composite can be assessed in three-dimensions without destruction of the composite. In this work, IM7/977–2, IM7/5555, and IM7/5276-1 coupons were uniaxially tested in a tensile substage, Graphs that convey microcracking density information as a function of applied load were created for [0/90/90/0] laminates. The three dimensional geometry and connectivity of microcracks and other damage in these samples were investigated through microtomographic reconstruction.
Comparison of the Experimental Behavior of a Shape Memory Alloy in Compression and Tension
Authors: Hesse Tobias , Ghorashi Mehrdaad , Inman Daniel J.
Published: May 2008

The concept of Shape Memory Alloy (SMA) has been a subject of extensive research in the recent few years. In many SMA applications, wire elements have been used in order to control structural specifications like shape and stiffness. Since a wire can only be subjected to tensile forces, the available theoretical models for DMA discuss only the tensile loading. The present paper is an endeavor to overcome this shortcoming. It gives experimental resluts for tension and compression tests on specimens (having different geometries) made of an identical shape memory alloy. The corresponding results are compared with each other. Using stress-strain diagrams, several important material properties are obtained. These parameters can then be implemented in SMA models in order to analyze and predict the mechanical behavior of SMA elements subjected to compression.
Influence of Topological Characteristics of a Brazed Joint Formation on Joint Thermal Integrity
Authors: Zhao Hui , Salazar Abraham J. , Sekulic Dusan P.
Published: May 2008

Adequate thermal integrity of brazed joints is a critical feature of a state-of-the-art compact heat exchanger design. New generations of aluminum compact heat exchangers with highly augmented heat transfer surfaces (such as micro-channeled extruded tubes in conjunction with composite AA3003/AA4343 multi-louvered fin foils) can provide significantly enhanced thermal performance—if the related manufacturing process, e.g., controlled atmosphere brazing (CAB) is performed flawlessly. However, empirical evidence indicates that often, even under a very tight brazing process control, design requirements imposed by heat transfer considerations lead to a more or less poor joint formation. This paper deals with an analysis of thermal features of a fin-tube joint as a function of topological alterations of the AA4343 joint filet size formed by materials processing during brazing. These alterations are caused by poor wetting and/or pronounced Si diffusion and/or increased liquid clad penetration. These phenomena lead to a less than optimal joint formation and will be illustrated by both empirical evidence and theoretical predictions. Based on numerical predictions of a joint topology formed by the surface tension driven reactive flow of molten metal, and subsequently verified by empirical evidence gathered through both laboratory and industrial testing, several topology alterations were devised as being representative for thermal integrity studies, and thermal characteristics of corresponding fin-tube joints were determined in terms of the spreading thermal contact resistance and corresponding temperature fields. Numerical predictions of joint topology were devised with an in-house developed finite element code and verified by Surface Evolver code. Temperature distributions established within selected fin-tube joint configurations were simulated using CFD software (FLUENT). Experimental data were obtained using a computer controlled transparent hot zone with an ultra high purity nitrogen background atmosphere.
Pulsed Spray Generation for Microfluidic Applications
Authors: Wittren Danielle , Shekarriz Reza , Forster Fred K.
Published: May 2008

Electrospray is the atomization of liquid caused by an applied electric field. Much research has been done based on dc electrical excitation of liquid transported to a nozzle under constant flow conditions. In contrast, very little research has been conducted in the area of pulsed electrospray, i.e. atomization based on time-varying electrostatic excitation. We report for the first time that his technique is capable of 1) spray-on-demand for a range of volume flow rates, pulse heights, pulse widths, pulse train frequencies and 2) continuous spray with higher energy efficiency compared to dc excitation in terms of flow rate per watt of electrical power.
Electrokinetic Particle Migration in Heterogeneous Electrolyte Systems
Authors: Devasenathipathy Shankar , Santiago Juan G. , Yamamoto Takahiro , Sato Yohei , Hishida Koichi
Published: May 2008

This paper presents a preliminary evaluation of an electrokinetic process for the buffer transfer and stacking of charged colloidal particles in solution. The mechanism exploits the effects of particle stacking across stacking across streamlines in a flow with electrical conductivity gradients transverse to the flow direction. Particle velocity fields and particle concentration measurements in a T-shaped microchannel system are presented. Upon application of an electric field, negatively charged particles are extracted from a low conductivity stream and stacked into a high conductivity stream. A simplified numerical model of the process with a commercial software code captures the generation of a transverse electric field.
Investigation Into the Utilization of Peanut Fibers in Nonwovens
Authors: Bieak Nicole , George Brian R.
Published: May 2008

Peanuts are one of the leading food crops produced in the United States today. One of the problems of peanut production is disposal of the shells, or hulls, of the peanut, which are generally landfilled. The current research focused on obtaining fibers from the shells, characterizing them, and creating nonwoven fabrics containing these fibers, which were also characterized. The fibers obtained ranged in length from 0.6 cm to 6.3 cm, and were generally stiff. Wet laid nonwovens were produced and a variety of bonding methods such as needlepunching and latex bonding were performed. Latex bonding gave the best results, and the resulting fabrics were characterized in terms of strength, moisture, and light penetration, and thermal insulation capability. The fabrics had similar light and moisture penetration properties as some commercially available erosion control fabrics and thus may be suitable for this purpose. The fabrics also retained some heat, and may be suitable for insulation purpose.
Nonlinear Vibrations in a Parametrically Excited Fluid-Structure Interaction System With One-to-One Internal Resonance
Authors: Ikeda Takashi
Published: May 2008

Theoretical resonance curves prove that a structure’s resonance can facilitate liquid sloshing even when the internal resonance ratio is one-to-one. An investigation of nonlinear sloshing liquid vibrations in a rectangular tank supported by an elastic structure that is subjected to a vertical and sinusoidal excitation reveals that liquid sloshing occurs when the structure’s natural frequency is approximately equal to the natural frequency of sloshing, that is, in the state of one-to-one internal resonance, and that amplitude-modulated motions appear when the condition of the internal resonance deviates to some extent. A special consideration of the nonlinear inertia effects of liquid force and the use of Galerkin’s method help derive the differential (modal) equations governing the dynamic behaviors of the fluid-structure interaction system, while van der Pol’s method helps express the theoretical resonance curves. These theoretical results are in quantitative agreement with the experimental data.
Analysis on Critical Phenomena of a Hysteretic System
Authors: Chen Z. , Wu Z. Q. , Yu P.
Published: May 2008

In this paper, a nonlinear mechanical system with external forcing is investigated to study the critical phenomena of the system. The system involves a von der Pol type damping and a hysteretic damper representing a restoring force. Numerical simulations are used to show that under an external exciting force, the hysteretic restoring force may not follow the routes described by a conventional form of piecewise function, but exhibit some irregular behavior. We call this unusual situation the critical phenomenon of the system. Simulations results suggest that a device with hysteretic property (e.g., the damper considered in this paper) may change its typical characteristics under external forcing. This new finding may enhance the study of nonlinear dynamical systems with hysteretic property under external excitement.
Analytical Study on a Dynamical Behavior of Loading Buckets Interacting With Bulk Materials
Authors: Yoshida Mitsuhiro , Morii Shigeki
Published: May 2008

A new analytical model has been developed to calculate the dynamical behavior of a column on which buckets loading and interacting with bulk materials, such as iron ore and coal with various grain sizes, are set. A set of linear equations of motion was obtained by considering the effective load, the stiffness, and the friction of materials. From the analysis of the equation, the growth of vibration in a column was indicated, which was caused by the cross term of a stiffness matrix because of the interaction between buckets and a material. In addition, bucket speed was found to affect the damping of the vibration through the critical condition Δxω∼vB where Δx is bucket displacement, ω is the characteristic frequency of a column, and v is bucket speed. A simplified characteristic function was obtained for the stability of a system and compared with the results of a laboratory-scale experiment in order to evaluate the analytical model.
Numerical Simulation of an Electroosmotic Micromixer
Authors: Chen Han , Zhang Yanting , Mezic Igor , Meinhart Carl , Petzold Linda
Published: May 2008

We present a micromixer fabricated using MEMS technology which takes advantage of electroosmosis to mix fluids. A time dependent electric field is applied and the resulting electroosmosis perturbs the low Reynolds number flow. It is shown that the electric field can be deemed quasi-steady and the electroosmotic slip boundary condition can be applied when the incompressible Navier Stokes equation is solved. Both the electric field and the electroosmotic flow are simulated numerically. Study of the particle traces shows folding and stretching of material lines, and a positive Lyapunov exponent is found which indicates chaotic-like mixing.
Experimental Investigation of the Energy Dissipated in a Magneto-Rheological Damper for Semi-Active Vehicle Suspensions
Authors: Goncalves Fernando D. , Ahmadian Mehdi
Published: May 2008

Magneto-rheological (MR) fluid dampers are often characterized by their field-dependent yield stress. This fielddependent yield stress and their fast response time make MR fluid dampers attractive alternatives to conventional viscous dampers. In comparing passive dampers with MR dampers, an equivalent viscous damping coefficient is often found from the energy dissipated by the MR damper. This study considers the energy dissipated by the MR damper under semi-active control. A hybrid control policy for semi-active vehicle suspensions is considered. A quarter car rig was used to evaluate the dynamics of the hybrid suspension using an MR damper. The steady-state performance of hybrid control is investigated with regard to the RMS displacements and accelerations of the sprung and unsprung masses. A frequency domain analysis is also presented. The transmissibilities of the sprung and unsprung masses are found using a range specific chirp signal. Results indicate that hybrid control with equal contributions from skyhook and groundhook can offer benefits to both the sprung and unsprung masses. With the performance of the hybrid semi-active suspension known, the study then considers the energy dissipated by the MR damper under hybrid control. An investigation into the possible correlation between performance and the energy dissipated by the MR damper is presented. Force-displacement curves are generated and an energy ratio is introduced. The energy ratio is the energy metric used to evaluate the energy dissipation of the MR damper. The energy ratio is defined as the ratio of the energy dissipated by the MR damper and the energy input into the system. The results indicate that the MR damper under hybrid control can dissipate nearly 70% of the energy input to the system.
Investigation of Structural and Material Effects on Crashworthiness of Advanced High Strength Steel Columns
Authors: Ben-Yahia Faycal , Nemes James A. , Hassani Farid
Published: May 2008

An experimental and numerical study was performed to evaluate the crashworthiness of several advanced high strength steels. The behavior of two Dual Phase (DP) steels and an HSLA steel are compared by examining the crush response of longeron column specimens, experimentally and computationally. The closed section columns, fabricated by spot welding formed channel sections, in both single hat and double hat configurations were exposed to 182 kg and 454 kg axial impacts at different velocities. Final column height and impact force history were recorded and compared with results of finite element simulation of the columns. Good agreement was found between experiments and computations.
Blow-Down Valve Noise and Interactions With Downstream Orifice Plates
Authors: Karczub Denis G. , Catron Fred W. , Fagerlund Allen C.
Published: May 2008

In a blow-down situation as might occur at a natural gas processing facility, noise levels are very high and significantly exceed the noise levels one would normally associate with a control valve. As the blow-down operation is an infrequent event, this may be permissible but requires consideration of the duration of these high noise levels to ensure that occupational noise exposure limits and acoustic fatigue limits are not exceeded. Tests of noise levels due to an 8-inch control valve in a 12-inch pipeline under blow-down conditions are compared here with noise level predictions based on the IEC standard. Consideration is also given to the impact of placing an orifice plate downstream of the control valve as is often done to reduce pressure drop across the valve in the expectation that control valve noise levels will be reduced. Simple orifice plates often installed by plant operators to achieve this goal are shown to have an adverse impact, and it is shown that a multi-hole diffuser or low-noise control valve should instead be used.
The Development of a Wayside Detection System for the Identification of Hunting Rail Car Trucks
Authors: Harrison Harold , Snyder Todd , GeMeiner William
Published: May 2008

A hunting truck detector was developed to identify that small portion of the rail car population that exhibits hunting behavior under normal operating speeds. An algorithm called Hunting Index (HI) was developed to produce a reliable descriptor of hunting behavior without the benefit (and expense) of a fully instrumented measuring zone. A correlation study was performed to relate very low values of the Hunting Index with ride quality to help screen rail cars for their usefulness as carriers of ride sensitive cargo.
Locomotive Cab Occupant Protection
Authors: Zolock John D. , Tyrell David C.
Published: May 2008

The effectiveness of fitting a locomotive cab with a passive inflatable restraint system utilizing inflatable structures, and interior padding to protect the operator has been evaluated for the in-line collision scenario. It is a challenge to design a system that increases protection for the locomotive operator within the cab during accidents, while allowing that operator to react to a specific situation by choosing either to leave or remain in the seat or cab. Numerous strategies have been proposed to increase locomotive cab occupant protection; however, most of these proposals have either required an active response from the cab occupants, e.g., getting into a refuge, or inhibited the potential for fleeing the cab, e.g., seatbelts. In this study, the occupant protection of a typical locomotive cab interior with a vertical console-stand style control is compared with the occupant protection of an interior modified with the addition of two tube-shaped inflatable structures for secondary impact injury mitigation. The crashworthiness performances of these two interior arrangements are compared for in-line train-to-train collision scenarios that approximate a locomotive-led train collision with another locomotive or cab car-led train. The analysis uses, as a basis, accident data and information on the crashworthiness performance of the locomotive interior in a train-to-train collision between a standing locomotive-led consist and a moving cab car-led consist conducted on January 31, 2002 at the Transportation Technology Center in Pueblo, Colorado. An analysis model is developed and validated using the full-scale train-to-train test locomotive interior/occupant experiment. The interior/occupant model then serves as a means of interpolating to different crash pulses, and with the alternative protection method using inflatable tube-like structures and interior padding. A range of locomotive operator sizes is investigated, as well as a range of selected initial seating positions for the locomotive operator.
Dynamic Properties of Squeeze Type Mount Using MR Fluid
Authors: Ha Jong-Yong , Ahn Young Kong , Yang Bo-Suk , Kim Dong-Jo , Ahmadian Mehdi
Published: May 2008

This paper presents an investigation of damping characteristics of a squeeze mode type MR (Magneto-Rheological) mount. Since the damping property of an MR fluid is changed by the variation of the applied magnetic field strength, the squeeze mode type MR mount proposed in this study has variable damping characteristics. In the present work, the performance of the mount was experimentally investigated according to the magnetic field strength and exciting frequency. The experimental results show that the MR mount can effectively reduce the vibration amplitude in a wide frequency range by controlling the field strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents in this study and MR effect is reduced by increasing exciting frequency.
Emissions From Waste-to-Energy: A Comparison With Coal-Fired Plants
Authors: Albina Dionel O. , Themelis Nickolas J.
Published: May 2008

Nationwide data of the emissions from waste-to-energy and coal-fired power plants arecompared. The emissions of sulfur dioxide and hydrogen chloride, particulate matter, nitrogen oxides and trace elements, such as cadmium, lead and mercury are compared, both in terms of thermal energy input and electrical energy output. The results of the study have shown that emissions of sulfur dioxide, particulate matter and nitrogen oxides were lower from waste-to-energy (WTE) facilities than from coal-fired plants. Hydrogen chloride emissions are higher in WTE flue gases. Emissions of cadmium, lead and mercury from WTE and coal-fired plants are nearly the same.
Boundary Layer Solution for the Turbulent Swirling Decay Flow Through a Fixed Pipe: SBR at the Inlet
Authors: Najafi A. F. , Saidi M. H. , Sadeghipour M. S. , Souhar M.
Published: May 2008

In this study the developing turbulent swirling pipe flow is investigated both numerically and analytically. Governing equations are derived accompanying the boundary layer assumptions. Uniform and solid body rotation (SBR) distributions are taken into account for the axial and tangential velocities at the inlet of the pipe, respectively. Beyond the boundary layers, the flow pattern is considered to be the potential flow. Making use of the fourth-order Runge-Kutta scheme, the numerical solution of the differential equations is obtained. Further more, by simplifying the governing equations for large Rossby number, the analytical solution is performed. The results of numerical and analytical swirl intensity have been compared showing reasonable agreement. As an alternative solution, a CFD analysis has been done as well, having applied FLUENT software to support the ability of our methodology.
Compact Spinning: A Critical Review
Authors: Kumar Akshay , Ishtiaque S. M. , Salhotra K. R.
Published: May 2008

Compact spinning is a novel concept generated through re-engineering of established ring spinning process by attaching a pneumatic zone to existing ring spinning machine. Compact spinning achieves a remarkable improvement in yarn quality and yarn structure through better utilization of fibre properties. The advantageous yarn characteristics provide better opportunities for cost savings in subsequent processing stages. Another interesting aspect is the possibility of developing new textile products using compact spinning. There are three major manufacturers in the field of compact spinning machines namely, Sussen (Elite spinning), Rieter (Comfor spin), and Zinser (Air-Com- Tex 700). First launch of Elite spinning machine in India faced a setback due to few practical problems like inadequate lubricating film on ring (does not allow the maximum spindle speed to be achieved), higher maintenance cost, higher labour cost and apron clogging due to accumulation of fly. However, with further developments compact spinning will certainly be the future of ring spinning, on account of its higher productivity and yarn quality.
Measurements of Bluff Body Wake Flow Around a Conformable Flow Control Surface
Authors: Ericson David A. , Jonson Michael , Koopmann Gary
Published: May 2008

The vortex street is a unique type of unsteady flow separation seen commonly in flow over a bluff body with a characteristic periodic wake. A consequence of the periodic flow is that the drag and lift forces acting on the body also oscillate periodically. When the wake shedding frequency is near a structural frequency, flow induced resonance will occur. The continuing interest in the study of vortex street generation is propelled by the ever-present nature of these flows in a variety of applications including aerodynamics, hydrodynamics and underwater acoustics. Recent advances in material science and the development of high power density actuators have led to the study of adaptive structure technology wherein the vorticity of periodic flows can be actively controlled by changing the ‘bluffness’ or shape of the body. In this paper, the development and experimental testing of a two-dimensional shape-variable flow control surface are discussed in relation to the generation and manipulation of periodic flow separation. Two series of wind tunnel tests were designed to evaluate the potential of the morphing structure that replaced a section of the trailing edge of a symmetric airfoil. The test section successfully demonstrated a smooth transition between three prescribed trailing edge profiles ranging from sharp to blunt. Unsteady pressure spectra were measured near the trailing edge for three different shape profiles over a range of speeds between 50 and 110 ft/s. The measured pressure spectra amplitudes were compared to previously-published surface pressure spectra of a similar, two-dimensional, blunt edge foil. A second set of tests was performed to measure the resulting flow field in the direction transverse to the flow and downstream from the airfoil. Velocity measurements were made using a traversing hot-wire probe at three trailing edge configurations and speeds of 50, 70 and 90 ft/s. The corresponding Reynolds number based on wake thickness ranged from 3.9–9.8 × 104. Measured vortex shedding frequencies varied between approximately 50 to 130 Hz at the different trailing edge profiles. This type of change in the vortex shedding frequency can be used to reduce flow-induced vibration and its associated noise generation by avoiding shedding frequencies at operating speeds that coincide with airfoil resonances.
An Analytical Optimization Algorithm for Wind Energy Coupled GSHP Systems for Sustainable Building HVAC
Authors: Kilkis Birol I.
Published: May 2008

Effective utilization of low-enthalpy energy resources in heating, ventilating, and air-conditioning (HVAC) of sustainable buildings require a careful optimization to assure the most economical coupling of HVAC systems with low-enthalpy energy resources. In one of the two separate prior studies an optimization algorithm for the optimal coupling of heat pumps and radiant panel heating and cooling systems was developed. In the second prior study an optimization algorithm for driving ground source heat pumps with wind turbines was developed. In this study these two algorithms were combined for a compound utilization of alternative energy resources. This paper describes the optimization algorithms, emphasizes their importance in achieving a cost effective combined application, and discusses the results obtained from the examples given.
Extended Hamilton’s Principle for Fluid-Structure Interaction
Authors: Benaroya Haym , Wei Timothy
Published: May 2008

The problem of vortex-shedding from bluff bodies has been examined for over a century, as reflected by the extensive literature on the subject. The focus of these foregoing researches can be split into two broad categories: investigations into the flow characteristics around a body in a flow, and studies of the response of a bluff body to the forces from the flow.
Dynamic Stresses During Structural Impacts
Authors: Leishear Robert A. , Morehouse Jeffrey H.
Published: May 2008

Dynamic stresses that occur when an object strikes a structure can be described by considering both vibration theory and conservation of energy principles. An object striking a simple beam is used as one of several examples. The complete stresses are found by adding the stresses obtained from a vibration equation to the stresses found by using a conservation of energy equation. When combined, these two stresses establish the maximum stress in a structure subject to impact. This solution assumes that each point within the beam acts as a linear system, reacting to the dynamic application of a load to the structure. When struck, the surface of the beam is momentarily compressed, and the beam bends. The equations describe both the localized stresses at the point of impact and the bending stresses in the beam following impact. These equations are then extended to an elastoplastic case, using a bilinear model to describe the dual natured linear elastic and linear plastic material behavior. The general solution technique is applicable to cases other than the simple beam.
Determination of Mechanical Properties of Thin Film on Silicon Wafer
Authors: Wu Enboa , Yang Albert J. D. , Shao Ching-An , Yen C. S.
Published: May 2008

Nondestructive determination of Young’s modulus, coefficient of thermal expansion, Poisson ratio, and thickness of a thin film has long been a difficult but important issue as the film of micrometer order thick might behave differently from that in the bulk state. In this paper, we have successfully demonstrated the capability of determining all these four parameters at one time. This novel method includes use of the digital phase-shifting reflection moire´ (DPRM) technique to record the slope of wafer warpage under temperature drop condition. In the experiment, 1-um thick aluminum was sputtered on a 6-in silicon wafer. The convolution relationship between the measured data and the mechanical properties was constructed numerically using the conventional 3D finite element code. The genetic algorithm (GA) was adopted as the searching tool for search of the optimal mechanical properties of the film. It was found that the determined data for Young’s modulus (E), Coefficient of Thermal Expansion (CTE), Poisson ratio (ν), and thickness (h) of the 1.00 um thick aluminum film were 104.2Gpa, 38.0 ppm/°C, 0.38, and 0.98 um, respectively, whereas that in the bulk state were measured to be E=71.4 Gpa, CTE=23.0 ppm/°C, and ν=0.34. The significantly larger values on the Young’s modulus and the coefficient of thermal expansion determined by this method might be attributed to the smaller dislocation density due to the thin dimension and formation of the 5-nm layer of Al2O3 formed on top of the 1-um thick sputtered film. The Young’s Modulus and the Poisson ratio of this nano-scale Al2O3 film were then determined. Their values are consistent with the physical intuition of the microstructure.