bluuebunny/crossref_metadata_2025 huggingface dataset:
The Couple That Prays Together: Race and Ethnicity, Religion, and Relationship Quality Among Working‐Age Adults
Authors: Ellison Christopher G. , Burdette Amy M. , Bradford Wilcox W.
Published: July 2010

A substantial body of research has shown that relationship quality tends to be (a) lower among racial and ethnic minorities and (b) higher among more religious persons and among couples in which partners share common religious affiliations, practices, and beliefs. However, few studies have examined the interplay of race or ethnicity and religion in shaping relationship quality. Our study addresses this gap in the literature using data from the National Survey of Religion and Family Life (NSRFL), a 2006 telephone survey of 2,400 working‐age adults (ages 18–59), which contains oversamples of African Americans and Latinos. Results underscore the complex nature of the effects of race and ethnicity, as well as religious variables. In particular, we found that couples' in‐home family devotional activities and shared religious beliefs are positively linked with reports of relationship quality.
Conflict Resolution in Mexican‐Origin Couples: Culture, Gender, and Marital Quality
Authors: Wheeler Lorey A. , Updegraff Kimberly A. , Thayer Shawna M.
Published: July 2010

This study examined associations between Mexican‐origin spouses' conflict resolution strategies (i.e., nonconfrontation, solution orientation, and control) and (a) gender‐typed qualities and attitudes, (b) cultural orientations, and (c) marital quality in a sample of 227 couples. Results of multilevel modeling revealed that Mexican cultural orientations were positively associated with solution orientation, and Anglo cultural orientations were negatively associated with nonconfrontation. Expressive personal qualities were negatively associated with control, whereas instrumental qualities were positively related to control. Links between conflict resolution and marital quality revealed that control and nonconfrontation were associated with spouses' ratings of marital negativity. In some cases, different patterns emerged for husbands and wives. Discussion highlights the role of culture and gender dynamics in marital relationships.
Peroxisomes as dynamic organelles: peroxisomal matrix protein import
Authors: Wolf Janina , Schliebs Wolfgang , Erdmann Ralf
Published: July 2010

The heterogeneity of peroxisomal matrix proteins which are imported in a folded, even oligomeric state, requires adaptive and dynamic properties of the translocation machinery. Dynamic multicompartmental subcellular distribution of peroxisomal proteins is governed by the accessibility of targeting signals. Conformational changes of peroxisomal targeting receptors upon cargo‐binding might serve as a docking ‘quality control’. Although the mechanisms are not understood in detail, recent work suggests the existence of a transient translocon within the peroxisomal membrane. Rapid formation and disassembly of the transient import pore ensures the integrity of the peroxisomal membrane barrier for small metabolites. In this review, we will focus on the regulatory aspects of peroxisomal matrix protein import.
Evolution of the star formation histories of BLAST galaxies
Authors: Dye Simon , Eales Steve , Moncelsi Lorenzo , Pascale Enzo
Published: July 2010

We have measured star formation histories (SFHs) and stellar masses of galaxies detected by the Balloon-borne Large Aperture Submillimetre Telescope (BLAST) over ∼9 deg2 centred on the Chandra Deep Field-South. We have applied the recently developed SFH reconstruction method of Dye et al. to optical, near-infrared and mid-infrared photometry of 92 BLAST galaxies. We find significant differences between the SFHs of low-mass (≲1011 M⊙) and high-mass (≳1011 M⊙) systems. On average, low-mass systems exhibit a dominant late burst of star formation which creates a large fraction of their stellar mass. Conversely, high-mass systems tend to have a significant amount of stellar mass that formed much earlier. We also find that the high-mass SFHs evolve more strongly than the low-mass SFHs. These findings are consistent with the phenomenon of downsizing observed in optically selected samples of galaxies.
Walls of secrecy and silence
Authors: Van De Bunt Henk
Published: July 2010

Research Summary

Most analysts of the causes of the contemporary credit crunch have concluded that the supervising agencies failed in their duties. The same is true for studies of several major fraud scandals, including the Madoff affair and the Dutch construction fraud. The remedy seems immediately obvious: more and better regulation and supervision. However, this line of reasoning seems somewhat simplistic by ignoring the question of how illegal activities can remain hidden for many years from supervising agencies, victims, and bystanders. This research article argues that the problem also lies in the successful concealment of illegal activities by the perpetrators and in the presence of silence in their social environment.

Policy Implications

The cases analyzed in this article suggest that financial misconduct also could be controlled by breaking the conspiracies of silence. The strengthening of supervision is unlikely to be effective without simultaneous efforts to encourage people to speak out and to give them incentives to want to know and to tell the truth.
REVIEW: Nonpharmacological Therapies for Atrial Fibrillation
Authors: Meshil Mark Alber , Bhakta Deepak
Published: July 2010

In recent years, nonpharmacological therapies for atrial fibrillation (AF) have emerged given the limitations of medical therapy. Advancements in particular have been made in the areas of radiofrequency catheter ablation and AF surgery, and have been accompanied by substantial technological improvements. This article will discuss several different modalities of nonpharmacological AF management including catheter ablation, AF surgery and device‐based therapy.
Contact Time Study of Microsystems Actuated by Ramp-Input Voltages
Authors: Moghimi Zand M. , Rashidian B. , Ahmadian M. T.
Published: July 2010

This paper presents a model to analyze contact phenomenon in microsystems, actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEM-FDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also investigated. It is shown that magnitude and position of applying the reverse voltage is very important in preventing pull-in instability.
A Methodology of an Automotive Engine Cooling Using a Phase Change Material
Authors: Kim Kibum , Choi Kyung-wook , Lee Ki-hyung , Lee Kwan-soo
Published: July 2010

The size of a cooling inventory is generally designed based on which size can endure the excessive heat load situations that occur sporadically. As a result, cooling systems are often too large for most normal driving modes. There have been numerous efforts to downsize the automotive engine cooling system using novel concepts and strategies (e.g. THEMIS cooling system, CoolMaster, UltimateCooling). However, in terms of the system design, preserving the passive cooling strategy may be simpler and more practical than implementing any major changes. Vetrovec (2008) proposed the use of a heat accumulator that has a phase change material (PCM) within the automotive cooling system. Excessive heat generated during severe operating conditions is stored in the heat accumulator, and it is dissipated during periods of low heat load. The heat dissipation capacity of the radiator and the amount of coolant in the cooling system are normally designed such that the system can sustain itself at peak heat load during acceleration and hill ascents in hot summer periods. Therefore, the unnecessarily large cooling inventory creates an overloaded vehicle which increases the fuel consumption rate. A heat accumulator which averages out the peak heat loads can reduce the entire cooling system remarkably in terms of both its volume and weight. Effective cooling in automobiles is beneficial in reducing harmful emissions as well as improving fuel economy. A simulation was conducted to validate the feasibility of using a novel cooling strategy that utilized the heat load averaging capabilities of a phase change material (PCM). Three prototypes were designed: full size, down sized, and a down sized prototype with a heat accumulator containing the PCM inside. When the full size of the cooling inventory was downsized by 30%, this smaller design failed to dissipate the peak heat load and consequently led to a significant increase in the coolant temperature, around 25 °C greater than that in the full size system. However, the peak heat load was successfully averaged out in the downsized system with a heat accumulator. Experimental study is also on-going to validate the simulation results and find more suitable PCM for the application.
High Throughput Continuous Fabrication of Large Surface Area Microstructured PDMS
Authors: DiBartolomeo Franklin J. , Trinkle Christine A.
Published: July 2010

Rapid creation of devices with microscale features is a vital step in the commercialization of a wide variety of technologies, such as microfluidics, fuel cells and self-healing materials. The current standard for creating many of these microstructured devices utilizes the inexpensive, flexible material poly-dimethylsiloxane (PDMS) to replicate microstructured molds. This process is inexpensive and fast for small batches of devices, but lacks scalability and the ability to produce large surface-area materials. The novel fabrication process presented in this paper uses a cylindrical mold with microscale surface patterns to cure liquid PDMS prepolymer into continuous microstructured films. Results show that this process can create continuous sheets of micropatterned devices at a rate of 3.94 in2/sec (100 mm2/sec), almost an order of magnitude faster than soft lithography, while still retaining submicron patterning accuracy.
Fast Harmonic MEMS Simulation With Arnoldi Model Order Reduction
Authors: Binion David , Chen Xiaolin
Published: July 2010

Recent years has witnessed a large increase in the use of vibrating Micro-Electro-Mechanical-Systems (MEMS) especially in the expanding wireless telecommunication industry. In particular, the use of microresonators to generate or filter signals has facilitated a reduction in the size of many popular cell phones. Advances in microfabrication have increased the ability to create complex MEMS devices. Finite Element Analysis (FEA) has widely been used in the design of these devices. To obtain accurate simulations of complex MEMS devices, a dense FEA mesh is required resulting in computationally demanding simulation models. Arnoldi Model Order Reduction has been investigated and implemented to improve the computational efficiency of MEMS simulations. Using ANSYS, a popular FEA program, a micro resonator model was created. With Arnoldi, a Krylov subspace was extracted from the model and the model was projected onto the subspace reducing the model size. A harmonic simulation over normal operating frequencies was performed on the reduced model and compared with a simulation of the original model. It was found that the computational time was drastically reduced through the use of Arnoldi while achieving similar accuracy as compared to the original model.
Research on Reliability Design Theory and Methods of CNC System
Authors: Wang Taiyong , Liu Qingjian , Wang Yunfeng , Yue Jianhai , Jin Dafeng
Published: July 2010

This paper presents the methods on the structure reliability design of embedded computer numerically controlled (CNC) system. An effective reliability model is developed and tested in a real-time CNC system. The evaluation method for the importance of the reliability of each function module of CNC systems is also investigated. Fuzzy mathematics is used to judge the importance of module reliability design. Cases studies have been performed to validate and illustrate all the analysis.
Prediction Method of Thrombus Formation Process in Separation and Reattachment Blood Flow Using Lattice Boltzmann Method
Authors: Tamagawa Masaaki
Published: July 2010

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow.
Finite Element Approach to Model Displacement Control of Smart Beams Using Photostrictive Optical Actuators
Authors: Rahman Mosfequr , Jackson John E.
Published: July 2010

The objective of this research work is to investigate the displacement control of smart beams of different boundary conditions using photostrictive optical actuators. The authors have developed a computational method useful for design of systems incorporating thin film photostrictive actuators. The element has been implemented in an in-house finite element code. A finite element for static analysis of photostrictive thin films has already been developed and verified with analytical analysis approach of another author. Also the effect of different parameters such as actuator thickness, incident light intensity and convective heat transfer coefficient in the actuation of beam using the thin film photostrictive actuators has been investigated by the authors. In this current work, derived finite element for static analysis of photostrictive thin films has been used to investigate the application of photostrictive actuators for optimum displacement control of beam structure of various boundary conditions. Studies are performed on the effects of various actuator location and length on photoactuation. Photostrictive materials are ferrodielectric ceramics that have a photostrictive effect. The photostrictive effect arises from a superposition of the photovoltaic effect and the converse piezoelectric effect. Photostrictive materials are (Pb, La)(Zr, Ti) O3 ceramics doped with WO3, called PLZT, exhibit large photostriction under uniform illumination of high-energy light. Photostrictive actuators can directly convert photonic energy to mechanical motion. Photostrictive materials can produce strain as a result of irradiation from high-intensity light. Neither electric lead wires nor electric circuits are required. Thus, photostrictive actuators are relatively immune from electrical interference. They have potential use in numerous MEMS devices where actuation of microbeams is a common phenomenon.
Modeling and Simulation of pH Dependent Isotachophoresis
Authors: Shim Jaesool , Dutta Prashanta , Ivory Cornelius F.
Published: July 2010

This paper presents a mathematical model for pH gradient ITP in a microfluidic system. The mathematical model is based on mass conservation, charge conservation and electroneutrality condition in the system. A finite volume based numerical model is developed to simulate pH dependent isotachophoresis (ITP) in microfluidic devices. Numerical results of pH dependent ITP are obtained for straight and dog-leg microchannels. For both channels, five ionic components are used to simulate the model ITP system. The ITP results obtained from dog-leg microchannel capture the band broadening and band dispersion observed in T-channel junction. However, no such dispersion is noticed for ITP in the straight microchannel.
Evaluation of a Thermal Interface Material Fabricated Using Thermocompression Bonding of Carbon Nanotube Turf
Authors: Hamdan Amer M. , Cho Jeong H. , Johnson Ryan D. , Bahr David F. , Richards Robert F. , Richards Cecilia D. , Jiao Jun
Published: July 2010

In this work, the use of vertically aligned carbon nanotubes (VACNTs) as thermal interface materials is presented. The VACNT structure is fabricated on 4×4 mm silicon substrates using chemical vapor deposition (CVD). These VACNT structures can be transferred to other substrates using a thermocompression bonding process; the process transfers the VACNTs to metalized silicon die which are tested after that as thermal interface materials. Two configurations of VACNTs were tested: one with a full coverage of VACNTs and one with patterned VACNTs. For the full coverage turf a thermal interface resistance as low as 1.082 cm2K/W was obtained, while a thermal interface resistance of 0.044 cm2K/W was obtained for the patterned turfs.
Accuracy of External Force Measurements Based on Particle Tracking Velocimetry
Authors: Laughlin Blaine , Tabatabaie Assad , Huang Peter
Published: July 2010

In microfluidic systems external forces are frequently applied to fluids or colloidal suspensions in order to accomplish or enhance mass transport tasks. The complexities of microscale geometries and material properties, however, can cause discrepancies between theoretical predictions and the actual values of the applied force. Therefore a calibration experiment is necessary to validate the actual magnitude of the applied force. One method of such in vivo calibration is through observations of tracer particle motions using particle tracking velocimetry (PTV). In microfluidic applications, the tracer particles of choice are typically submicron in diameter and therefore undergo significant Brownian motion. Further complicating the matter is the presence of the solid channel boundaries whose presence can lead to hindered Brownian motion and position-dependent hydrodynamic drag. In this paper we present a Langevin simulation study of the effects of normal and hindered Brownian motions, and the time between image acquisitions on the accuracy of external force measurements based on PTV. It is found that the relative strength between the random forces that cause Brownian motion and the applied external force plays a critical role in measurement accuracy. We also found that hindered Brownian motion and the associated sampling trajectory biases contribute additional force measurement inaccuracies when PTV is conducted in the vicinity of a solid boundary.
Arbitrary Geometry Cellular Automata for Elastodynamics
Authors: Hopman Ryan K. , Leamy Michael J.
Published: July 2010

This study extends a recently-developed [1] cellular automata (CA) elastodynamic modeling approach to arbitrary two-dimensional geometries through development of a rule set appropriate for triangular cells. The approach is fully object-oriented (OO) and exploits OO conventions to produce compact, general, and easily-extended CA classes. Meshes composed of triangular cells allow the elastodynamic response of arbitrary two-dimensional geometries to be computed accurately and efficiently. As in the previous rectangular CA method, each cell represents a state machine which updates in a stepped-manner using a local “bottom-up” rule set and state input from neighboring cells. The approach avoids the need to develop partial differential equations and the complexity therein. Several advantages result from the method’s discrete, local and object-oriented nature, including the ability to compute on a massively-parallel basis and to easily add or subtract cells in a multi-resolution manner. The extended approach is used to generate the elastodynamic responses of a variety of general geometries and loading cases (Dirichlet and Neumann), which are compared to previous results and/or comparison results generated using the commercial finite element code, COMSOL. These include harmonic interior plate loading, uniform boundary traction, and ramped boundary displacement. Favorable results are reported in all cases, with the CA approach requiring fewer degrees of freedom to achieve similar accuracy, and considerably less code development.
Micro-Propulsion System of a Thermospheric Explorer CubeSat
Authors: Udrea Bogdan , Huang Adam , Cosgrove Russell , Doe Richard , Malsbury John
Published: July 2010

The major design driver for the Dipping Thermospheric Explorer (DipTE) CubeSat mission is that the satellite shall fly a significant amount of orbit arcs at altitudes of 300km and below. It is assumed that the DipTE satellite will be released in a circular orbit above the altitudes of scientific interest for the mission. A propulsion system will be employed to make the orbit elliptic and satisfy the design driver. The apogee of the elliptic orbit will be at the altitude of the initial circular orbit. The inclination of the orbit will stay the same. A few design iterations of the mission converged to a satellite configuration capable of storing 0.375 kg of propellant, and a propulsion system with a specific impulse Isp of 86 s. About 90 % of the total impulse of 313 Ns stored on board was budgeted to perform orbital maneuvers, with a 1 N thruster orbital maneuvering thruster (OMT). The remainder of 10% of the propellant mass has been budgeted for attitude control maneuvers, such as those performed during detumbling and initial attitude acquisition. The attitude control maneuvers are performed with the thrusters of a reaction control system (RCS). The 12 two-dimensional (2D) microthrusters of the RCS produce 40 mN each and are installed such that they provide three-axis control of the spacecraft. This paper describes the preliminary design of the propulsions system.
Size-Dependent Elastic Behavior of Silicon Nanofilms: Molecular Dynamics Study
Authors: Sadeghian Hamed , Goosen Johannes F. L. , Bossche Andre , Thijsse Barend J. , van Keulen Fred
Published: July 2010

In this paper, the size-dependence of the elastic behavior of silicon nanofilms terminated by (100) surfaces is studied by means of molecular dynamics with the modified embedded atom method (MEAM). The results indicate that the (100) surfaces undergo 2×1 reconstruction, which significantly influences the mechanical properties of ultra-thin films. The simulations are carried out at room temperature and structural relaxation is performed. The effective Young’s modulus, in extensional mode, is determined for different thicknesses. The surface energy, surface stress and surface elasticity of layers near the surfaces (non-bulk layers) in the thin silicon films are obtained. The surface properties of nanofilms of a few layers are shown to deviate from thicker films, suggesting a size-dependence of surface parameters and, especially, surface energy. Finally, the results of a recently developed semi-continuum approach are compared with the molecular dynamics results. Below 3 nm, there is a difference between the effective Young’s modulus, calculated by the semi-continuum approach and that provided by MD, suggesting that the continuum approach can no longer provide accurate results.
Theory and Design of Practical Metamaterials for Acoustic Cloaking
Authors: Popa Bogdan-Ioan , Cummer Steven A.
Published: July 2010

Significant research has recently been dedicated to reducing the interaction between acoustic waves and given objects. The coordinate transformation theory provides an elegant approach to the design of coatings capable of reaching this goal. First demonstrated for electromagnetic waves [1], this method has later been adapted to acoustic waves [2–5]. Its appeal stems from its generality: it can be applied to obtain coatings capable to conceal objects of arbitrary shapes and sizes. Moreover, its efficacy depends only on our ability to create materials having the right acoustic properties. However, these properties are quite restrictive. They include inhomogeneity, i.e. material parameters that vary continuously with position, and a high degree of anisotropy. In practice, one would relax these constraints but reduce the performance of the design. For example, in many instances an inhomogeneous material can be approximated by thin layers of homogeneous media. However, a large number of such layers are usually required to obtain acceptable results [6].
Modeling and Simulation of the Coupled Mechanical-Electrical Response
Authors: Gao Zhan , Tuncer Ergin A. , Cuitin˜o Alberto M.
Published: July 2010

Dielectric elastomer (DE) is one type of electro-active polymers (EAP) that responds to electrical stimulation with a significant shape and size change. As EAPs, dielectric elastomers are lightweight, inexpensive, pliable and can be fabricated into various shapes, all of which are attractive properties to justify the intense research in the field. This paper presents a nonlinear, electrical and mechanical coupled, large deformation finite element formulation for DEAs. Maxwell’s equations for the electroquasistatic fields were solved simultaneously with equation of linear momentum. The hyperelastic Ogden model and total Maxwell stress methods were combined to describe the material. The formulation was based on the weak forms of Maxwell’s equation and linear momentum expressed in the reference configuration. The closed form consistent tangent moduli for dielectric elastomers were derived. To our knowledge, the large deformation electric-mechanical coupled finite element application and the closed-form expressions of the tangent moduli have not been reported previously. The results of the simulation have demonstrated the validity of the method from the computational aspect.
Hybrid Control and Transport Using Bacteria-Driven Microbiorobots
Authors: Steager Edward , Sakar M. Selman , Kim Dalhyung , Kumar Vijay , Pappas George J. , Kim Min Jun
Published: July 2010

We are examining techniques for manipulation of microfabricated elements using arrays of bacteria as microactuators. Flagellated Serratia marcescens bacteria are attached to microstructures using a blotting technique that creates a bacterial monolayer carpet. These bacterial carpets naturally self-coordinate to propel the microstructures. We refer to these constructs as microbiorobots (MBR). Generally, the motion pattern of the MBRs is largely rotational in nature, and the center of mass deviates no more than several hundred microns from its original position. However, the angular velocity and orientation of the MBRs may be controlled using ultraviolet light stimulus, and the translational position may be adjusted using electrokinetic stimulus. Here, we demonstrate precision positional adjustment of a microbiorobotic transporter that is used to engage and transport cube-shaped particles 10 μm on each side.
Use of the Freely-Swimming, Serratia Marcescens Bacteria to Enhance Mixing in Microfluidic Systems
Authors: Peysepar Mahyar , Shafii Mohammad Behshad , Rasoulian Ramin , Jamalifar Hosein , Fazeli Mohammad Reza
Published: July 2010

Mixing has become a challenge in micro-fluidic systems because of the low Reynolds number in micro-channels. The method which is implemented in this paper is to use freely-swimming bacteria to enhance the mixing process. Accordingly, the Serratia marcescens bacteria were used for this matter. The mixing performance of the system is quantified by measuring the diffusion rate of Rhodamine B in a particular section of a channel connected to a chamber with varying Rhodamine B concentration. The concentration of Rhodamine B was measured using the Laser Induced Fluorescence (LIF) technique. The channel is in the form of a pipe and is closed on the extending side. In this paper, it is demonstrated that the corresponding diffusion coefficient can be augmented by bacterial participation and that this augmentation can be continued for several hours, depending on the environmental conditions. Additionally, it is shown that the mixing process reacts in response to modifications to the chemical environment of the system, which in turn affect the metabolic activity of the bacteria. Also, a 30 mM glucose buffer was used to show the impact of food on the performance of the bacterial system. It is thus shown that the existence of glucose increases the mixing ability of bacteria.
Parametric Influence on the Sound Absorption Coefficient of Porous Asphalt
Authors: Sachakamol Punnamee , Dai Liming
Published: July 2010

This research intends to develop a method for predicting the sound absorption coefficient of various porous highway pavement materials. Since many of the existing prediction models for acoustic properties and traffic noise still have limitations and problems with accuracy, sound absorption coefficients are measured with the impedance tube method to verify numerical values obtained from the model. Results obtained from the experiment and numerical simulations are compared and presented to reveal the effect and influence of the control parameters.
Properties, Characterization and Fiber Extrusion Simulation of Novel Amorphous Polymers for Optical Application
Authors: Gipson Kyle G. , Brown Philip J. , Stevens Kathryn A. , Cox Christopher L.
Published: July 2010

Polymeric optical fibers are generally manufactured in the same manner as traditional glass (silica) fibers. As technology advances, more efficient, cost effective materials and processes are being developed to serve the duties of optical materials within networks. Traditional polymer optical fibers are comprised of hydrocarbon amorphous polymers and include polymethyl methacrylate (PMMA) and polystyrene (PS). These types of polymers have inherent issues in optical applications such as their signal absorption loss. This is largely due to the vibration of the carbon-hydrogen (C-H) bond contained in the polymer backbone. Therefore, to broaden the scope of polymer optical fibers, novel exotic amorphous polymers are being developed. One such polymer family, reported to have excellent optical properties, is perfluorocyclobutyl aryl ethers (PFCB), which do not exhibit the strong C-H vibrations associated with absorption loss. At this time, little is known of the intrinsic properties of PFCBs as well as the behavior of the polymer melt during extrusion. This work will review the thermal and rheological properties of two PFCB polymers: biphenylvinyl ether (BPVE) and hexafluoroisopropylidene vinyl ether (6F). The information gathered from the analysis of these two intrinsic properties will be used as the input data for a fiber extrusion simulation model, FiSim. The application of the FiSim software was done in order to produce a viable limited range of process conditions for which fibers could be melt spun.
Implementation of a Semi-Implicit Pressure-Based Multigrid Fluid Flow Algorithm on a Graphics Processing Unit
Authors: Shinn Aaron F. , Vanka S. P.
Published: July 2010

A semi-implicit pressure based multigrid algorithm for solving the incompressible Navier-Stokes equations was implemented on a Graphics Processing Unit (GPU) using CUDA (Compute Unified Device Architecture). The multigrid method employed was the Full Approximation Scheme (FAS), which is used for solving nonlinear equations. This algorithm is applied to the 2D driven cavity problem and compared to the CPU version of the code (written in Fortran) to assess computational speed-up.
High Residual Stress Between Zirconia Grains Observed With Laue Micro-Diffraction
Authors: Bale Hrishikesh , Hanan Jay C.
Published: July 2010

Highly focused synchrotron X-rays were used to measure residual stresses in dental grade yttria stabilized zirconia. The technique uses a sub-micron polychromatic beam to produce Laue diffraction spots. Diffraction spots from individual grains of zirconia provide the deviatoric stress tensor of the residual stress. Significant local grain-grain stresses were observed nearly 10–15% of the 1500 grains examined exhibiting stresses above 500 MPa. These residual stresses influence crack propagation and fracture.
Fatigue Properties of a Graded Steel Component
Authors: Bru¨ckner-Foit Angelika , Zeismann Frank , Besel Michael
Published: July 2010

Rods of a Cr-V alloyed heat treatable steel in a soft annealed condition were locally heated to a temperature above austenization temperature and then subjected to an integrated forming and cooling procedure. The resulting component possesses a graded microstructure consisting of martensite, deformed base material and a transition phase with mixed microstructure. Miniature specimens were cut from this component which allowed assessing the local properties of the graded steel both under tensile loading and under cyclic loading. The martensite region had high strength and showed comparatively long lifetimes. The dominant damage accumulation process was identified to be crack initiation from local defects. The base material, on the other hand, contained numerous crack initiation sites. In-situ observation of the damage accumulation process on the surface showed how macroscopic cracks were formed by microcrack growth and coalescence. It is shown how these findings can be incorporated into a mechanism-based lifetime model.
High Pressure On-Chip Valves for Thermoplastic Microfluidics
Authors: Chen Chien-Fu , Liu Jikun , Chang Chien-Cheng , DeVoe Don L.
Published: July 2010

A high-pressure microvalve technology based on the integration of discrete elastomeric elements into rigid thermoplastic chips is described. The low-dead-volume valves employ deformable polydimethylsiloxane (PDMS) plugs actuated using a threaded stainless steel needle, allowing exceptionally high pressure resistance to be achieved. The simple fabrication process is made possible through the use of poly(ethylene glycol) (PEG) as a removable blocking material to avoid contamination of PDMS within the flow channel while yielding a smooth contact surface with the PDMS valve surface. Burst pressure tests reveal that the valves can withstand over 24MPa without leakage.
A Modern Approach to Bayesian Inference for Risk and Reliability Analysis
Authors: Smith Curtis L. , Kelly Dana L. , Vedros Kurt G.
Published: July 2010

Recent years have seen significant advances in the use of risk analysis in a variety of applications. Because risk and reliability models are intended to support these applications, it is critical that inference methods used in these models be robust and technically sound. The inference method described in this paper is that of Bayesian Inference. The inference we describe uses a modern computational approach known as Markov chain Monte Carlo (MCMC). MCMC methods work for simple cases, but more importantly, they work efficiently on very complex cases. Recently, with the advance of computing power and improved analysis algorithms, MCMC is increasingly being used for a variety of Bayesian inference problems. In the paper, an open-source program called OpenBUGS (commonly referred to as WinBUGS) is used to solve the inference problems that are described. The approach that is taken is to provide analysis “building blocks” that can be modified, combined, or used as-is to solve a variety of challenging problems. This paper provides an overview of guidelines for the evaluation of risk and reliability-related data. It is aimed at those familiar with risk and reliability methods and provides a hands-on approach to the investigation and application of a variety of risk and reliability data assessment methods, tools, and techniques.
Fabrication and Characterization of Thermoelectric Oxide La1−xSrxCoO3 (x∼0.05) Nanofibers
Authors: Xu Weihe , Xu Shiyou , Smiriglio Dante , Shi Yong
Published: July 2010

The P-type perovskite oxides La1−xSrxCoO3 (x∼0.05) are a promising group of complex oxide thermoelectric materials. The thermal electric properties of these complexes are expected to increase significantly when their dimension was reduced to nano scale. In this project, the La1-xSrxCoO3 (x∼0.05) nanofibers, with diameters in the range of ∼30–80 nm, were prepared by the electrospinning process. Various substrates such as aluminum foil, silicon dioxide, and a specially designed tester were used to collect and anneal the nanofibers. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to characterize these thermoelectric nanofibers. Finally, a thermoelectric property tester device was developed and used to measure the voltage output of the nanofibers due to the Seebeck effect. The detected signal was at the mV level and the Seebeck coefficient was positive.
Magnon-Phonon Interactions in a Ferromagnetic Media: Reflection and Refraction of Magneto-Elastic Waves
Authors: Harutyunyan Satenik , Davis Robert B.
Published: July 2010

Reflection and refraction of magneto-elastic waves at the interface of two ferromagnetic half-spaces is considered. The space is in an external homogeneous magnetic field, the direction of which coincides with direction of the initial magnetization vector. A slipping contact on the interface of two ferromagnetic semi-spaces is considered. The existence of new type of waves is shown. These waves are localized on the interface of two ferromagnetic media and accompany the reflection and transmission waves and exist because of incident waves on the interface of two magneto-elastic media, and magneto-elastic properties of the media. These types of waves named as an accompanying surface magnetoelastic (ASM) waves. An analytical expression for the magnitudes of reflection, refraction, and ASM waves are derived. Coefficients of mentioned waves are strongly dependent on the applied magnetic field, material properties of each medium, as well as on frequency and the angle of an incident elastic wave. It has been shown that an applied magnetic field can totally eliminate or strengthen transmission and reflection waves and can be a control parameter for exchanging energies between these waves. Also, by eliminating transmission and reflection waves the magnetic field is able to control the ASM wave magnitudes. A new wave filtration mechanism can be drawn from these effects.
Flow-Through Nanohole Array Based Sensing
Authors: Escobedo Carlos , Wood Paul , Gordon Reuven , Brolo Alexandre G. , Sinton David
Published: July 2010

Integration of nanohole array based sensing in microfluidic environments has been focus of several recent works. However, nanohole array based sensing performed to date has involved dead-ended holes that fail to harness the potential benefits provided by flow-through operation. Potential benefits include enhanced transport of reactants via nanoconfinement and solution sieving. Here, we describe computer based analysis related with nanofluidic transport and solid mechanics under a flow-through sensing scheme. We also demonstrate experimental nanofluidic flow-through transport and its application to real-time monitoring of self-assembled monolayer creation and biomarker detection.
Investigation of the Properties of PEEK-Nanotube Composites Prepared by Solution Methods
Authors: Bartolucci Stephen F. , Mago Gaurav , Gevgilili Halil , Vural Seda , Dikovics Kimberly , Kalyon Dilhan M. , Fisher Frank T.
Published: July 2010

Poly(ether ether ketone) (PEEK) is an aromatic, very high temperature semi-crystalline polymer which exhibits a technologically useful combination of mechanical and chemical properties. In this study carbon nanofibers (CNFs) were used to prepare nanocomposites from PEEK using a polymer crystallization technique at intermediate temperatures. The solution processing technique was used to uniformly disperse the CNFs in the polymer solution and to prepare the nanocomposite samples with different loading of CNFs. Microstructural characterization shows dispersion at very low loading of CNFs, but agglomerates were formed at higher loading. Thermal analysis was used as a means to understand the effect of CNFs on the physical properties of the PEEK nanocomposites.
Enhanced Vehicle Identification Utilizing Sensor Fusion and Statistical Algorithms
Authors: Roussel Stephane , Porumamilla Hemanth , Birdsong Charles , Schuster Peter , Clark Christopher
Published: July 2010

Several studies in the area of vehicle detection and identification involve the use of probabilistic analysis and sensor fusion. While several sensors utilized for identifying vehicle presence and proximity have been researched, their effectiveness in identifying vehicle types has remained inadequate. This study presents the utilization of an ultrasonic sensor coupled with a magnetic sensor and the development of statistical algorithms to overcome this limitation. Mathematical models of both the ultrasonic and magnetic sensors were constructed to first understand the intrinsic characteristics of the individual sensors and also to provide a means of simulating the performance of the combined sensor system and to facilitate algorithm development. Preliminary algorithms that utilized this sensor fusion were developed to make inferences relating to vehicle proximity as well as type. It was noticed that while it helped alleviate the limitations of the individual sensors, the algorithm was affected by high occurrences of false positives. Also, since sensors carry only partial information about the surrounding environment and their measured quantities are partially corrupted with noise, probabilistic techniques were employed to extend the preliminary algorithms to include these sensor characteristics. These statistical techniques were utilized to reconstruct partial state information provided by the sensors and to also filter noisy measurement data. This probabilistic approach helped to effectively utilize the advantages of sensor fusion to further enhance the reliability of inferences made on vehicle identification. In summary, the study investigated the enhancement of vehicle identification through the use of sensor fusion and statistical techniques. The algorithms developed showed encouraging results in alleviating the occurrences of false positive inferences. One of the several applications of this study is in the use of ultrasonic-magnetic sensor combination for advanced traffic monitoring such as smart toll booths.
Defining Nascent Bone by the Molecular Nanomechanics of Mineralized Collagen Fibrils
Authors: Buehler Markus J.
Published: July 2010

Here we focus on recent advances in understanding the deformation and fracture behavior of collagen, Nature’s most abundant protein material and the basis for many biological composites including bone, dentin or cornea. We show that it is due to the basis of the collagen structure that leads to its high strength and ability to sustain large deformation, as relevant to its physiological role in tissues such as bone and muscle. Experiment has shown that collagen isolated from different sources of tissues universally displays a design that consists of tropocollagen molecules with lengths of approximately 300 nanometers. Using a combination of theoretical analyses and multi-scale modeling, we have discovered that the characteristic structure and characteristic dimensions of the collagen nanostructure is the key to the ability to take advantage of the nanoscale properties of individual tropocollagen molecules at larger scales, leading to a tough material at the micro- and mesoscale. This is achieved by arranging tropocollagen molecules into a staggered assembly at a specific optimal molecular length scale. During bone formation, nanoscale mineral particles precipitate at highly specific locations in the collagen structure. These mineralized collagen fibrils are highly conserved, nanostructural primary building blocks of bone. By direct molecular simulation of the bone’s nanostructure, we show that it is due to the characteristic nanostructure of mineralized collagen fibrils that leads to its high strength and ability to sustain large deformation, as relevant to its physiological role, creating a strong and tough material. We present a thorough analysis of the molecular mechanisms of protein and mineral phases in deformation, and report discovery of a new fibrillar toughening mechanism that has major implications on the fracture mechanics of bone. Our studies of collagen and bone illustrate how hierarchical multi-scale modeling linking quantum chemistry with continuum fracture mechanics approaches can be used to develop predictive models of hierarchical protein materials. We conclude with a discussion of the significance of hierarchical multi-scale structures for the material properties and illustrate how these structures enable one to overcome some of the limitations of conventional materials design, combining disparate material properties such as strength and robustness.
Prevention Through Design: An Idea Whose Time Has Come
Authors: Morse John S. , Batzer Stephen A.
Published: July 2010

Addressing occupational safety and health needs in the design process to prevent or minimize the work-related hazards and risks associated with the construction, manufacture, use, maintenance, and disposal of facilities, materials, and equipment,” is how the National Institute for Occupational Safety and Health (NIOSH) defines Prevention Through Design (PtD) [1]. This concept is an idea whose time has come, including its extension to products, since product-related injuries also occur outside of the workplace. Using PtD techniques on consumer products will yield significant safety benefits. Besides the desire to provide well designed products, save lives, prevent injuries and avoid lawsuits, engineers have a professional responsibility to promote safety. The fundamental canon of the American Society of Mechanical Engineers (ASME) Code of Ethics states, “Engineers shall hold paramount the safety, health and welfare of the public in the performance of their professional duties.” [2] The first fundamental canon of the National Society of Professional Engineers (NSPE) Code of Ethics [3] is virtually identical. Codes and standards alone are usually not a guarantor of safety, as no document can foresee every application and situation. Codes and standards differ widely in their ability to produce a safe product or process simply from adherence to their requirements. Further, many codes and standards do not consider foreseeable or known misuse, which must be considered in PtD. PtD requires hazard evaluation followed by affirmative measures that address hazards and failure modes until an acceptable, likely nonzero, level of risk is reached. Such measures provide safety even when a momentary and foreseeable level of carelessness or inattention occurs.
Finite Element Modeling and Simulation of a Two-Transducer Through-Wall Ultrasonic Communication System
Authors: Wilt K. R. , Scarton H. A. , Roa-Prada S. , Saulnier G. J. , Ashdown J. D. , Lawry T. J. , Das P. K. , Gavens A. J.
Published: July 2010

A finite element simulation of a through-wall ultrasonic communication system which permits data to be transferred from the inside of a sealed metal vessel to the outside without the need for physical penetrations is introduced. Two transducers are aligned axially on either side of a thick solid stainless steel wall. The outside transducer is forced with a continuous sinusoidal voltage at the crystal’s nominal 1 MHz longitudinal resonant frequency, launching a wave into the wall. The transmitted beam is partially reflected off of the inside of the wall where the inside transducer is located. The amplitude of the reflected wave is modulated by switching the electrical impedance placed across the leads of the inside transducer. The reflected wave is received at the outside transducer and the continuous wave amplitude is sensed to detect the transmitted data bits. The system is modeled and simulated using a commercial finite element modeling package. A coupled stress-strain and piezoelectric analysis is performed using an axisymmetric geometry. The model represents an existing system from which physical measurements were taken. Excellent correlation between the model and system were observed and the model has been used to further optimize the communication system.