bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermo-Mechanical Analysis of Various Film Cooling Hole Geometries
Authors: Ramesh Sridharan , LeBlanc Christopher , Ekkad Srinath , Alvin Mary Anne
Published: December 2013

Tripod hole film cooling designs can provide improved cooling with reduced coolant usage. It is essential to determine the impact of strong cooling near hole locations due to increased thermal gradients around the hole region. In this paper, efforts have been made to predict the same using a numerical analysis. Local temperature distribution on the blade surface causes different rates of expansion, resulting in a differential strain, furthering the impact of the numerical study and creating a need to understand the thermo-mechanical behavior of blade design. The thermal stresses that are generated near the film cooling holes are compared for different cooling hole shapes and eventually weigh the thermal advantage of a tripod hole over the cylindrical standard design. Standard k-ε was used to validate the CFD results, ensuring by a fine mesh of 5 million tetrahedrons. Validation includes comparison of the experimental results, with a numerical one where similar blade material and working temperatures are used. Upon validation, CFD was run again at engine temperature conditions with Haynes230 alloy as the blade material. Surface temperature contour enabled structural analysis using a finite element approach. Equivalent stresses (Von-Mises stresses) on the blade emerging from the analysis provided more information about stress dependency on blowing ratio.
Experimental Investigation of the Effect of Synthetic Jets on Local Heat Transfer Coefficients in Minichannels During Laminar and Turbulent Flow Conditions
Authors: Sykes David M. , Carpenter Andrew L. , Cole Gregory S.
Published: December 2013

Microchannels and minichannels have been shown to have many potential applications for cooling high-heat-flux electronics over the past 3 decades. Synthetic jets can enhance minichannel performance by adding net momentum flux into a stream without adding mass flux. These jets are produced because of different flow patterns that emerge during the induction and expulsion stroke of a diaphragm, and when incorporated into minichannels can disrupt boundary layers and impinge on the far wall, leading to high heat transfer coefficients. Many researchers have examined the effects of synthetic jets in microchannels and minichannels with single-phase flows. The use of synthetic jets has been shown to augment local heat transfer coefficients by 2–3 times the value of steady flow conditions. In this investigation, local heat transfer coefficients and pressure loss in various operating regimes were experimentally measured. Experiments were conducted with a minichannel array containing embedded thermocouples to directly measure local wall temperatures. Flow regimes ranged from laminar to turbulent. Local wall temperature measurements taken directly beneath the synthetic jet in a laminar flow regime indicated that when a synthetic jet was used, the heat transfer coefficient was increased as much as 2.8 times the value as when synthetic jets were not used. Significant heat transfer coefficient augmentation also propagated to the upstream location, where heat transfer was increased to 2.2 times the value as when the synthetic jets were not used. Additional measurements show that synthetic jets significantly altered the pressure loss coefficient of the minichannels and that this effect was more pronounced in laminar flow than in turbulent flow. The effect of operating frequency on heat transfer and pressure loss is also presented. It was shown that the optimal operating point for the synthetic jet within a minichannel was in transitional to weakly turbulent flow (2600<Re<4500) to maximize the increase in heat transfer coefficient and minimize the increase in pressure loss.
Numerical Study on Thermo-Hydraulic Performance in the Shell Side of Spiral-Wound Heat Exchanger
Authors: Zhang G. P. , Zeng M. , Li Y. , Niu Y. Z. , Wang Q. W.
Published: December 2013

The spiral-wound heat exchangers are widely used in industrial applications, but the mechanism of flow and heat transfer in shell side has not been clarified yet. A three-dimensional model is developed based on the FLUENT software in this study, with emphasis on quantifying the effects of the main geometry parameters, such as the tube number per circle in the first layer, the tube external diameter, the central cylinder diameter and the tube pitch, on the flow and heat transfer are discussed respectively. It is found that as the tube number per circle in the first layer increases, the Nusselt number increases and the pressure loss per unit length increases first and then decreases and the similar trend is obtained as the central cylinder diameter increases. The Nusselt number and pressure loss both increase with the increase of tube external diameter. As the tube pitch increases, the Nusselt number and the pressure loss both decreases.
Sensitivity of Thermal Transport and Phase-Change in Thin Porous Layers to the Distribution of the Solid Matrix
Authors: Konduru Vinaykumar , Medici Ezequiel , Allen Jeffrey S.
Published: December 2013

Understanding the water transport in the Porous Transport Layer (PTL) is important to improve the operational performance of polymer electrolyte membrane fuel cells (PEMFC). High water content in the PTL and flow channel decreases the transport of the gas reactants to the polymer electrolyte membrane. Dry operating conditions result in increased ohmic resistance of the polymer electrolyte membrane. Both cases result in decreased fuel cell performance. Multi-phase flow in the PTL of the fuel cell is simulated as a network of pores surrounded by the solid material. The pore-phase and the solid-phase of the PTL are generated by varying the parameters of the Weibull distribution function. In the network model, the mass transfer takes place in the pore-phase and the bulk heat transfer takes place in the both the solid-phase and liquid phase of the PTL. Previous studies have looked at the thermal and mass transport in the porous media considering the pore size distribution. In the present study, the sensitivity of the thermal and mass transport to the different arrangements of the solid-phase is carried out and the effect of different solid-phase distributions on the thermal and liquid transport in PTL of PEM fuel cell are discussed.
Steady State Temperature Gradients in a Non-Blinking Human Eye Prepared for Surgery
Authors: Abdelmessih Amanie N.
Published: December 2013

LASER surgery on the human eye is intended to reduce a person’s dependency on glasses or contact lenses. Any type of Laser surgery has heat effects on the eye. In laser surgery specific parts of the eye are exposed to concentrated high heat doses, too high heat at a certain spot results in permanent medical damage to the specific exposed eye cells. Precise temperature monitoring of the live interior of the human eye is not possible with the current technology. Published modeling assumes that the human eyeball is at a constant temperature, mostly at 37 °C. Understanding the exact temperature gradients in the prepared open human eyeball in room temperature before surgery is a first step in better understanding the heat effects of either laser surgery on specific treated spots of the cornea, or the effects of insertion of synthetic lenses in the human eye, or treating the retina with laser. In this article the anatomy of the human eyeball, dimensions, and properties are considered in constructing a finite element steady state thermal model of the normal open human eye for an adult, in preparation for surgery under normal room conditions. Also, room boundary conditions are used. Based on the model, the temperature gradients in the open eye are reported.
Understanding Enhanced Boiling With Triton X Surfactants
Authors: Cho H. Jeremy , Sresht Vishnu , Blankschtein Daniel , Wang Evelyn N.
Published: December 2013

Heat transfer performance in pool boiling is largely dictated by bubble growth, departure, and number of nucleation sites. It is a well known phenomenon that adding surfactants can lower the liquid-vapor surface tension and increase the bubble departure frequency, thereby enhancing heat transfer. In addition to faster departure rates, surfactants are observed to dramatically increase the number of nucleation sites, which cannot be explained by simple surface tension arguments. Furthermore, it is not well understood which surfactant properties such as chemical composition and molecular structure affect boiling most significantly. From our experiments using Triton X-100 and Triton X-114 nonionic surfactants, we attribute boiling enhancement mainly to adsorption to the solid-liquid interface. Using the Mikic-Rohsenow model for boiling, a simple linear adsorption model, and the Cassie-Baxter description for contact angle, we developed a model that shows agreement with experimental results. This work offers some insights on how to predict boiling enhancement based on surfactant chemistry alone, which may aid in choosing optimal surfactants for boiling in the future.
Modeling of Thermally Grown Oxide Layer Growth as a Moving Boundary Problem
Authors: Benissan Michael , Akwaboa Stephen , Jana Amitava , Mensah Patrick
Published: December 2013

Thermal efficiency of energy conversion systems such as gas turbines can be increased greatly with an increase in the turbine inlet temperature of combustion gases. However, this necessitates the use of efficient cooling techniques in addition to thermal barrier coatings (TBCs) to help significantly improve the life expectancy of gas turbine blades. The effect of TBC use is the formation of oxides, particularly alumina, at the interface of the ceramic top coat and bond coat material during in-service application. This effect is well known to cause failure of TBCs exposed to extreme high temperature environments. The objective of this paper is to present a micro-scale finite difference thermal model for the TBC-Substrate system that considers growth of the TGO layer and predicts in-situ thermal gradients. The governing equation is the transient heat diffusion equation discretized over a 1-D domain using mean value finite volume method with grid adaptation for zones involving depletion of bond coat (BC) material and TGO growth; hence, necessitating a moving interfacial boundary problem. The resulting algebraic equations are simultaneously solved in MATLAB to produce temperature distributions and BC/TGO interfacial locations. The model has utility in studying the evolution of residual stresses and hence prediction of TBC durability and failure.
Numerical Simulation of Air Sampling in Micro Scale Rising Bubbles
Authors: Mirzaee Kakhki Iman , Charmchi Majid , Sun Hongwei , Song Minghao
Published: December 2013

Capturing particles, mainly bio-particles, such as viruses and spores, from the air into a liquid is critical for air purification and analysis of the sampling systems. In the conventional impinger sampling systems, the air bubbles carrying the particles are injected into a liquid column. The particles are captured from the air into the liquid as the bubbles travel to the surface due to the buoyancy forces. This paper focuses on the numerical simulation of a newly developed microfluidic air sampling system. In this system, a microscale liquid column, equipped with an array of microchannels as pressure controlled gas injection points, is used for gas bubbling process for air sampling purpose. The air bubbles containing the particles are injected into the bottom of the microscale column filled with a liquid (such as water). As the microscale bubbles (of about 250∼500 microns) travel to the surface, a shear driven flow will develop within the bubbles and the airborne particles will follow the flow toward the boundary of the bubble. The inertia force of particles will result in the departure of particles from the flow into the liquid. The fraction of the particles departed from air bubble and trapped in the liquid represents the collection efficiency of the air sampler. For tracking the liquid/gas interface, the Volume-of-Fluid (VOF) method along with Youngs’ algorithm for geometric reconstruction of the free surface is used. The particle trajectories are predicted by integrating the force balance on each particle, which is based on a Lagrangian frame of reference. It is found that in addition to the particle departure during the bubble rising, a considerable amount of particles are trapped in the liquid during the air injection and bubble formation which may be due to the high velocity of the injected air and oscillation of the bubble interface. It is worth noting that this is the first time that the numerical simulation is performed to understand the whole air sampling process which was never addressed in the past. As a comparison, an experimental study was conducted to measure the collection efficiency. The fluorescent polystyrene latex particles with different diameters (diameters: 0.5, 1, 2 microns) were used in the experiment. The experimental results were compared with that of numerical simulation. Both the experiments and computations revealed that a collection efficiency of 90% can be achieved by the microfluidics based impinger, which is much higher than that of conventional, macro-scale, impinger systems. In addition to verifying the existing experimental work, this numerical simulation method provides a valuable tool to design and improve new generations of air sampling systems.
Visualization of Dynamic Contact Angle
Authors: Field Brandon S.
Published: December 2013

Capillary rise of air-water-solid systems have been recorded with high-speed video. Glass and metal have been used as the solid phase, and the dynamic shape of the meniscus and contact angle have been characterized. The advancing and receding contact angle is of interest in computational simulations of boiling flow, and the present visualizations attempt to quantify the dynamic aspects of contact line motion. The centroid of the capillary meniscus has been tracked in order to determine the force at the contact line based on a force balance of the elevated fluid phase. The solid phase is raised and lowered in the fluid at different rates to observe advancing and receding contact lines.
Optimization of an Urea Decomposition Chamber Using CFD and VR
Authors: Chen Xingjian , Tang Guangwu , Wu Bin , Zhou Chenn Q. , Colella Christopher P.
Published: December 2013

Selective Catalytic Reduction (SCR) is an important air pollution control process that consists of injecting ammonia (NH3) into the boiler flue gas and passing the flue gas through a catalyst bed where the NOx and NH3 react to form nitrogen gas (N2) and water vapor (H2O). [1] At a coal-fired power station, a decomposition chamber uses combustion air and a natural gas burner to provide the necessary temperature, air flow and pressure to convert the injected urea solution into ammonia gas. The inspections of this decomposition chamber indicate debris formations occurring at the burner/roof block the chamber from achieving proper temperature for conversion and redirect the burner flame/flow, which can potentially shift the flow pattern in the chamber. In order to identify the cause of this debris formation, Computational Fluid Dynamics (CFD) and Virtual reality fVR have been employed to simulate and visualize the flow distribution and species concentration inside this decomposition chamber. By analyzing the simulation data, excessive ammonia recirculation had been identified as the cause of the debris formation at the top of the chamber. Parametric studies have also been conducted to optimize the existing chamber design by introducing multiple turning vanes to eliminate the excessive recirculation, thus minimizing debris formation.
Recession Experiments and Modeling for Carbon Surface Oxidation Processes
Authors: Kurzawski Andrew , Ezekoye Ofodike A. , Koo Joseph H. , Yee Colin , Hardee Theodore
Published: December 2013

We examined numerical and experimental use of a coupled-transducer system comprised of a thermocouple temperature measurements and time of flight acoustic measurements to determine the recession rate of a carbon material. A problem in the use of ultrasonic transducers for high temperature thickness measurements is that the temperature of the specimen is not always known. The variation of the speed of sound with temperature makes this a challenging problem and the use of a limited number of temperature measurements helps to construct a temperature profile on which the acoustic time of flight measurement can be characterized. In the problem of interest, a high heat flux is directed towards the surface of a carbon based material. A temperature profile is set up in the material. Initially the heated face simply increases in temperature with no mass loss. With increasing heating and oxygen transport to the surface, the hot face begins to oxidatively erode. Temperature measurements Y (xi) are made at xi locations within the material. At the same time a time of flight measurement is made in the material. We can assume that the time of flight measurement takes place over a time period that is small relative to the time for which the spatial temperature variation evolves. As such, the time of flight measurement primarily involves a weighted spatial integration of a function of temperature. Given the temperature measurements and the time of flight measurement, we seek the recession rate or equivalently, the sample length. We develop a simple thermal model with appropriate representation of oxidation kinetics to describe the process. A simple inversion analysis is developed and tested on synthetic data to best fit the experimental data.
Experimental Heat Transfer Study of Aluminum Oxide Nanofluid Flow in Tubes for Laminar Thermal Entry Region
Authors: Tang Clement C. , Tiwari Sanjib , Cox Matthew W.
Published: December 2013

Experiments have been conducted to characterize the viscosity, thermal conductivity, and Nusselt number of aluminum oxide (Al2O3) nanoparticle dispersions at 6% vol. in liquid water flowing through circular tubes. Rheological characterization of the Al2O3–water nanofluid has shown that it exhibits a Newtonian fluid behavior for the shear rate range of 6 to 122 s−1 between 6 and 75°C. Measurements of the nanofluid thermal conductivity have been performed for temperatures between 6 and 55°C, and were found to be 8 to 17% higher than that of water. Heat transfer measurements for nanofluid flow in laminar thermal entry region have been conducted for three different test sections with L/D of 155, 194, and 299. The experimental results within this study indicate that the heat transfer characteristics of the Al2O3–water nanofluid flow are largely in agreement with conventional theory for single-phase flow.
Simulation of Counter-Current Gas-Liquid Churn Flow
Authors: Tekavčič Matej , Končar Boštjan , Kljenak Ivo
Published: December 2013

A transient simulation of air-water counter-current flow by the means of two-fluid model with interface sharpening is performed. The gas-liquid inhomogeneous model with both phases considered as incompressible is used. Turbulence is modelled for each phase separately using the two-equation eddy viscosity model. The numerical domain consists of an axisymmetric wedge with the porous wall inlet region representing a vertical pipe experimental test section. Evolution of volume fraction, velocities and pressure variations along the interface is presented. Simulation results are compared with the known experimental data (from the literature) for the wave frequency and velocity. The present simulation is also compared to a known numerical simulation found in literature that used volume of fluid method. Sensitivity study of several modelling parameters is performed to evaluate and discuss their impact on simulation results in an attempt to establish best practice guidelines for modelling of realistic counter-current flows, important in nuclear reactor systems.
Phase-Change Heat Transfer of Ethanol-Water Mixtures: Towards Development of a Distributed Hydrogen Generator
Authors: Moharana Manoj Kumar , Nemade Rohan M. , Khandekar Sameer
Published: December 2013

Hydrogen fuel from renewable bio-ethanol is a potentially strong contender as an energy carrier. Its distributed production by steam reforming of ethanol on microscale platforms is an efficient upcoming method. Such systems require (a) a pre-heater for liquid to vapor conversion of ethanol water mixtures (b) a gas-phase catalytic reactor. We focus on the fundamental experimental heat transfer studies (pool and flow boiling of ethanol-water mixtures) required for the primary pre-heater boiler design. Flow boiling results (in a 256 μm square channel) clearly show the influence of mixture composition. Heat transfer coefficient remains almost constant in the single-phase region and rapidly increases as the two-phase region starts. On further increasing the wall superheat, heat transfer starts to decrease. At higher applied heat flux, the channel is subjected to axial back conduction from the single-phase vapor region to the two-phase liquid-vapor region, thus raising local wall temperatures. Simultaneously, to gain understanding of phase-change mechanisms in binary mixtures and to generate data for the modeling of flow boiling process, pool-boiling of ethanol-water mixtures has also been initiated. After benchmarking the setup against pure fluids, variation of heat transfer coefficient, bubble growth, contact angles, are compared at different operating conditions. Results show strong degradation in heat transfer in mixtures, which increases with operating temperature.
The In Situ Adaptive Tabulation (ISAT) Algorithm for Reacting Flow Computations With Complex Surface Chemistry
Authors: Mazumder Sandip , Kumar Ankan
Published: December 2013

The In Situ Adaptive Tabulation (ISAT) procedure, originally developed for the efficient computation of homogeneous reactions in chemically reacting flows, is adapted and demonstrated for reacting flow computations with complex heterogeneous (or surface) reactions. The treatment of heterogeneous reactions within a reacting flow calculation requires solution of a set of nonlinear differential algebraic equations at boundary faces/nodes, as opposed to the solution of an initial value problem for which the original ISAT procedure was developed. The modified ISAT algorithm, referred to as ISAT-S, is coupled to a three-dimensional unstructured reacting flow solver, and strategies for maximizing efficiency without hampering accuracy and convergence are developed. These include use of multiple binary tables, use of dynamic tolerance values to control errors, and periodic deletion and/or re-creation of the binary tables. The new procedure is demonstrated for steady-state catalytic combustion of a methane-air mixture on platinum using a 24-step reaction mechanism with 19 species, and for steady-state three-way catalytic conversion using a 61-step mechanism with 34 species. Both reaction mechanisms are first tested in simple 3D channel geometry with reacting walls, and the impact of various ISAT parameters is investigated. As a final step, the catalytic combustion mechanism is demonstrated in a laboratory-scale monolithic catalytic converter geometry with 57 channels discretized using 354,300 control volumes (4.6 million unknowns). For all of the cases considered, the reduction in the time taken to perform surface chemistry calculations alone was found to be a factor of 5–11.
Thermal Characterization of Polymer Composites by Using the 3-Omega Method
Authors: Oh Dong-Wook , Kim Young , Choi Jun Seok , Kim Ook Joong , Lee Kong Hoon
Published: December 2013

Polymer composites having comparable thermal conductivity to stainless steel at room temperature are commercially available nowadays. Metal or carbon fiber and particles are added to base polymers to enhance mechanical and thermal performance. However for polymer composites having high additive concentration, characterizing mechanical and thermal properties of the composite may be a challenging problem due to an-isotropic natural and non-homogeneity. In this paper, a novel thermal property measurement method based on the 3-omega (3ω) is proposed for thermal analysis of polymer composites. Sensitivity and feasible limit of the 3ω method with “boundary mismatch assumption” is analyzed for measurement of polymer composites having broad range of thermal conductivity.
Mathematical Modeling of Draining of Dual-Strand Caster Tundish With Unequal Throughputs at United States Steel Corporation
Authors: Sinha Asish K. , Piccone Thomas J. , Miller Paul D.
Published: December 2013

Mathematical modeling of the tundish draining process was undertaken in response to the pouring of slag into the caster mold during draining of the dual-strand caster tundish at one of United States Steel Corporation’s plants before a tundish change. It was observed upon dumping of the tundish that the tundish skull was mostly slag on one side (the strand with the slag in the mold) and nearly all steel on the other. The current study attempted to reproduce the tundish draining event via mathematical modeling using the PHOENICS computational fluid dynamics software. The tundish draining was modeled for the case where the throughput of one strand was double that of the other strand. Transient flow modeling of the draining process included solving for the pressure and velocities for the two-phase slag-steel flows for two cases, one with a 6-inch thick slag layer and one with a 2-inch slag layer. The results showed that the draining process was affected significantly by the thickness of the initial slag layer. The simulations also qualitatively predicted the tendency of the slag to accumulate on the side with the higher throughput during tundish draining for a dual-strand tundish containing dams on both sides of the pouring area in the center.
Analytic Models for Temperature Distribution Near a Nanoantenna
Authors: Brock Casey N. , Walker Greg , Coppens Zack
Published: December 2013

Thermoplasmonic structures produce highly localized temperature fields. For simplicity, researchers often use a superposition of representative spheres to model the temperature in the non-conductive region (presumably a substrate) near the metallic structures deposited on the substrate. The superposition model provides reasonable solutions, but direct comparison to experiments is difficult because local temperature variations at the nanoscale are not accessible. Moreover, the model requires several approximations. Therefore, we compare this model to other analytic models to determine the efficacy of the superposition approach in capturing temperature distributions close to the surface of the substrate and to capture realistic boundary conditions. Results indicate that a 3D analytic model can relax approximations required for the superposition model and show that the superposition model consistently over-predicts the surface temperature.
Optimal Allocation of Heat Exchanger Inventory for Maximum COP and Exergetic Performance of a Two-Stage Vapor Compression Cycle
Authors: Abdel-Rahim Yousef M. , Sherif S. A.
Published: December 2013

In the present study the optimum heat exchanger inventory allocation to maximize the thermal performance of a two-stage vapor compression system with two evaporators has been investigated. Both the cooling (A/C) and heating (H/P) Carnot and non-Carnot non-isentropic cycles have been considered. The optimum operating ranges of cycle parameters that maximize both the coefficient of performance (COP) and exergetic efficiency (η2) of the cycles for both cooling and heating purposes are discussed. The research upon which this paper partly reports covered all possible ranges of cycle parameters using the Monte-Carlo method. For the Carnot cycle, maximum values of the cooling coefficient of performance (COPC), cooling exergetic efficiency (ηIIC), heating coefficient of performance (COPH), and heating exergetic efficiency (ηIIH) were found to be 9.6, 0.47, 10.7 and 0.87, respectively. The low-pressure (LP) thermal load and temperature difference in the condenser were found to critically affect both the A/C and H/P performance, while the heat conductance ratio and the mass flow rate ratio were found to have a pronounced effect on only the H/P performance. The best A/C and H/P cycle performance may be achieved by having the two evaporators with both the thermal load and mass flow rate in the high-pressure loop to be 20% less than that in the low-pressure loop. The analysis performed on the non-Carnot two-compressor, two-evaporator A/C and H/P non-isentropic cycles determined both the feasible and optimal ranges of variations of the controlling parameters. The combined maximum values of the low- and high-pressure evaporator thermal loads was found to be 10–15% lower than the maximum value of the condenser heat rejection rate, thus reflecting the relative sizes of these units as heat exchangers. Other factors that may help provide guidance for utilizing the system for cooling and heating purposes include the values of the COPC and COPH, the relative amounts of the mass flow rates in the low-pressure and high-pressure loops of the cycle, and the values of the low-pressure and high-pressure compressor powers.
Assessment of In Vitro Patellar Laxity in the Native Knee
Authors: Komosa Mark C. , Shalhoub Sami S. , Cyr Adam J. , Maletsky Lorin P.
Published: December 2013

Patellar instability is a frequent knee problem and relates to anterior knee pain [1–3]. Patellofemoral (PF) joint laxity is a multifactor problem that depends on the active stabilization from the quadriceps muscles, the passive stabilization from the ligaments and retinacular tissue in the PF joint, and the static stabilization from the articular geometries of the distal femur and patella. The purpose of this study was to use a novel patellar laxity instrument to measure patellar laxity and to assess subject-to-subject variation in patellar laxity.
Construction of 3D Human Knee Joint Models Using a 3D Statistical Deformable Model
Authors: Zhu Zhonglin , Li Guoan
Published: December 2013

Statistical shape model (SSM) has been established as a useful method for reconstruction of patient-specific 3D surface models, such as the hip or proximal femur using a single radiographic image of the joint [1, 2]. However, there are few studies that have reconstructed patient-specific 3D models of the entire knee joint. We propose to utilize the strong embedded spatial information in a 2D knee joint radiographic image to predict the 3D human knee joint shape model using the SSM method. We also present a preliminary study to test the accuracy of this method when applied to predict human knee joint shapes.
Application of a Density-Elastic Modulus Equation Developed for the Distal Ulna to Multiple Forearm Positions: A Finite Element Study
Authors: Neuert Mark A. C. , Austman Rebecca L. , Dunning Cynthia E.
Published: December 2013

Compared to experimental studies using strain gauges, finite element (FE) models are not limited to strain measurements at discrete locations and can be used to examine the continuous strain and stress field throughout bone. As such, they can be a useful tool for biomechanical investigations interested in stress and strain changes as a result of multiple loading conditions, implant designs, etc. Critical to their development is the assignment of material properties.
Pseudoelastic Hinges Promoting Muscle “Creep” as Opposed to Relaxation for the Rehabilitation of Spastic Syndromes
Authors: Viscuso Stefano , Garavaglia Lorenzo , Pittaccio Simone
Published: December 2013

The evolution of spastic pathologies as a consequence of brain damage is a complex phenomenon involving disuse, immobility and brain tissue remodeling [1]. The vicious circle leading to a worsening of the patients’ status proceeds through muscle shortening by contractures, disruption of the normal reflex behaviour and sensory disturbances. A way to prevent chronicity of major consequences could be to favour mobility and any residual use of the affected limb.
Nature-Inspired Design: Modeling the Biomechanics of the Seahorse Tail
Authors: Praet Tomas , Adriaens Dominique , De Beule Matthieu , Verhegghe Benedict
Published: December 2013

Billions of years of evolutionary pressure have forced organisms to develop efficient solutions to real-world problems. More and more engineers realize that they are faced with similar problems on a daily basis. Instead of trying to reinvent the wheel, one should first take a look at existing solutions, e.g. in nature. This nature inspired approach can be interesting for a multitude of engineering domains, including bioengineering.
Transport and Mixing in Patient Specific Abdominal Aortic Aneurysms With Lagrangian Coherent Structures
Authors: Arzani Amirhossein , Shadden Shawn C.
Published: December 2013

Abdominal aortic aneurysms (AAA) are characterized by disturbed flow patterns, low and oscillatory wall shear stress with high gradients, increased particle residence time, and mild turbulence. Diameter is the most common metric for rupture prediction, although this metric can be unreliable. We hypothesize that understanding the flow topology and mixing inside AAA could provide useful insight into mechanisms of aneurysm growth. AAA morphology has high variability, as with AAA hemodynamics, and therefore we consider patient-specific analyses over several small to medium sized AAAs. Vortical patterns dominate AAA hemodynamics and traditional analyses based on the Eulerian fields (e.g. velocity) fail to convey the complex flow structures. The computation of finite-time Lyapunov exponent (FTLE) fields and underlying Lagrangian coherent structures (LCS) help reveal a Lagrangian template for quantifying the flow [1].
Controllable nitrogen doping in as deposited TiO2 film and its effect on post deposition annealing
Authors: Deng Shaoren , Verbruggen Sammy W. , Lenaerts Silvia , Martens Johan A. , Van den Berghe Sven , Devloo-Casier Kilian , Devulder Wouter , Dendooven Jolien , Deduytsche Davy , Detavernier Christophe
Published: December 2013

In order to narrow the band gap of TiO2, nitrogen doping by combining thermal atomic layer deposition (TALD) of TiO2 and plasma enhanced atomic layer deposition (PEALD) of TiN has been implemented. By altering the ratio between TALD TiO2 and PEALD TiN, the as synthesized TiOxNy films showed different band gaps (from 1.91 eV to 3.14 eV). In situ x-ray diffraction characterization showed that the crystallization behavior of these films changed after nitrogen doping. After annealing in helium, nitrogen doped TiO2 films crystallized into rutile phase while for the samples annealed in air a preferential growth of the anatase TiO2 along (001) orientation was observed. Photocatalytic tests of the degradation of stearic acid were done to evaluate the effect of N doping on the photocatalytic activity.
Superluminal? You bet!
Authors: Higbie Jack
Published: December 2013

We have been told that nothing can travel faster than light, but in fact, most of the Universe has traveled away from us at superluminal speeds since time began, and in order to understand how that happens, we will need a brief introduction to cosmology and the relativistic Friedmann model for a radially expanding universe.
A Left-Hand Rule for Faraday's Law
Authors: Salu Yehuda
Published: December 2013

A left-hand rule for Faraday's law is presented here. This rule provides a simple and quick way of finding directional relationships between variables of Faraday's law without using Lenz's rule.
Complete Genome of Salmonella enterica Serovar Typhimurium Myophage Maynard
Authors: Tatsch Casey O. , Wood Thammajun L. , Chamakura Karthik R. , Kuty Everett Gabriel F.
Published: December 2013

Salmonella enterica
serovar Typhimurium is a pathogenic bacterium that has been a major concern for food and public safety. Phages infecting
S
. Typhimurium may prove to be useful therapeutics against this harmful bacterium. Here, we announce the complete genome of
S
. Typhimurium T4-like myophage Maynard and describe its features.
Thoracic aortic dissection presenting as acute coronary syndrome
Authors: Jackson Emma , Stewart Michael
Published: December 2013

A patient presented with symptoms consistent with non-ST elevation myocardial infarction (NSTEMI) and was given appropriate antiplatelet and anticoagulant therapy. Despite treatment of the NSTEMI and fluid resuscitation the patient remained persistently hypotensive. Further imaging demonstrated an extensive Stanford type A dissection extending from the aortic root to the left common iliac artery. The patient was taken to theatre and had an emergency hemiarch replacement with repair of the aortic root. Post surgery the patient had an uneventful recovery. We present this case to highlight the importance of considering dissection as a differential in patients presenting with chest pain and the lack of symptoms a patient with such a severe dissection can display.
Adolescent mental health and subsequent parenting: a longitudinal birth cohort study
Authors: Byford M , Abbott R A , Maughan B , Richards M , Kuh D
Published: December 2013

Background

Adolescent mental health problems are associated with a range of adverse outcomes in adulthood but little is known about the effects on adult parenting practices. This study aimed to examine prospective associations between adolescent conduct and emotional problems and subsequent parenting behaviours in adulthood.

Methods

The study sample comprised 1110 members from the MRC National Survey of Health and Development. Prospective data were collected from teacher reports of conduct and emotional problems at age 13 and 15 years and adult outcome measures of parenting included intellectual environment, cognitive stimulation, coercive discipline, parental interest and parental aspiration.

Results

In regression models adjusted for the confounding effects of social background, cognition and education, adolescent conduct problems predicted coercive parenting behaviours in adulthood. The effects of adolescent emotional problems on the development of coercive discipline practices were explained by covariates. Likewise, the inability of parents who displayed conduct problems in adolescence to provide an intellectually stimulating home environment was fully explained by the adjustment for education.

Conclusions

Adolescents who exhibit conduct problems are more likely to develop coercive styles of parenting.
Sixty years of antimicrobial use in animals: what is next?
Authors: Guardabassi Luca
Published: December 2013

This, the last in our series of feature articles celebrating 125 years of Veterinary Record, aims to provide an overview of antimicrobial use in animals. Starting with a journey through the history of antimicrobial use in animals, Luca Guardabassi gives his opinion on the current zoonotic risks associated with antimicrobial resistance and on how these risks might be tackled in the years to come.
Interrelationships between changes in anthropometric variables and computed tomography indices of abdominal fat distribution in response to a 1-year physical activity–healthy eating lifestyle modification program in abdominally obese men
Authors: Villeneuve Nicole , Pelletier-Beaumont Emilie , Nazare Julie-Anne , Lemieux Isabelle , Alméras Natalie , Bergeron Jean , Tremblay Angelo , Poirier Paul , Després Jean-Pierre
Published: December 2013

The objectives were to (i) measure the effects of a 1-year lifestyle modification program on body fat distribution/anthropometric variables; (ii) determine the interrelationships between changes in all these variables; and (iii) investigate whether there is a selective reduction in deep (DSAT) vs. superficial subcutaneous adipose tissue (SSAT) at the abdominal level following a 1-year lifestyle modification program. Anthropometric variables, body composition and abdominal and midthigh fat distribution were assessed at baseline and after 1 year in 109 sedentary, dyslipidemic and abdominally obese men. Reductions in anthropometric variables, skinfold thicknesses (except the trunk/extremity ratio) and fat mass as well as an increase in fat-free mass were observed after 1 year (p < 0.0001). Decreases in abdominal adipose tissue volumes were also noted (–23%, –26%, –18%, –19%, –17%, p < 0.0001 for total adipose tissue, visceral adipose tissue, subcutaneous adipose tissue, DSAT and SSAT, respectively). Adipose tissue areas at midthigh also decreased (–18%, –18%, –17%, p < 0.0001 for total, deep, and subcutaneous adipose tissue, respectively). A reduction (–9%, p < 0.0001) in low-attenuation muscle area and an increase (+1%, p < 0.05) in normal-attenuation muscle area were also observed. There was a positive relationship between changes in visceral adipose tissue and changes in DSAT (r = 0.65, p < 0.0001) or SSAT (r = 0.63, p < 0.0001). Although absolute changes in DSAT were greater than changes in SSAT, relative changes in both depots were similar, independent of changes in visceral adipose tissue. The 1-year lifestyle modification program therefore improved the body fat distribution pattern and midthigh muscle quality in abdominally obese men.
A HIGH ROBUSTNESS AND LOW COST CASCADING FAILURE MODEL BASED ON NODE IMPORTANCE IN COMPLEX NETWORKS
Authors: FAN WEN-LI , LIU ZHI-GANG , HU PING
Published: December 2013

In this paper, we investigate the trade-off problem between the high robustness against cascading failures and the low costs of network constructions in complex networks. Since the important nodes with highly connected components usually play a key role in the network structure and network dynamics, we propose an optimal capacity allocation model based on node importance. The novel model will increase the capacities of those important nodes but reduce the network construction cost with the appropriate capacity allocation parameter. Moreover, we also discover that our matching model can enhance the robustness against cascading failures on the IEEE 300 network.
TIGHT BOUNDS ON THE SYNTHESIS OF 3-BIT REVERSIBLE CIRCUITS: NFFr LIBRARY
Authors: YOUNES AHMED
Published: December 2013

The reversible circuit synthesis problem can be reduced to permutation group. This allows Schreier–Sims algorithm for the strong generating set-finding problem to be used to find tight bounds on the synthesis of 3-bit reversible circuits using the NFFr library. The tight bounds include the maximum and minimum length of 3-bit reversible circuits, the maximum and minimum cost of 3-bit reversible circuits. The analysis shows better results than that found in the literature for the lower bound of the cost. The analysis also shows that there are 2460 universal reversible sub-libraries from the main NFFr library.
MEASURING COSMOLOGICAL PARAMETERS WITH GAMMA RAY BURSTS
Authors: AMATI LORENZO , VALLE MASSIMO DELLA
Published: December 2013

In a few dozen seconds, gamma ray bursts (GRBs) emit up to ~1054 erg in terms of an equivalent isotropically radiated energy E iso , so they can be observed up to z ~ 10. Thus, these phenomena appear to be very promising tools to describe the expansion rate history of the universe. Here, we review the use of the Ep,i–E iso correlation of GRBs to measure the cosmological density parameter ΩM. We show that the present data set of GRBs, coupled with the assumption that we live in a flat universe, can provide independent evidence, from other probes, that ΩM ~ 0.3. We show that current (e.g. Swift, Fermi/GBM, Konus-WIND) and forthcoming gamma ray burst (GRB) experiments (e.g. CALET/GBM, SVOM, Lomonosov/UFFO, LOFT/WFM) will allow us to constrain ΩM with an accuracy comparable to that currently exhibited by Type Ia supernovae (SNe–Ia) and to study the properties of dark energy and their evolution with time.
ENHANCING CONSENSUS UNDER OPINION BIAS BY MEANS OF HIERARCHICAL DECISION MAKING
Authors: PERONY NICOLAS , PFITZNER RENÉ , SCHOLTES INGO , TESSONE CLAUDIO J. , SCHWEITZER FRANK
Published: December 2013

We study the role of hierarchical structures in a simple model of collective consensus formation based on the bounded confidence model with continuous individual opinions. For the particular variation of this model considered in this paper, we assume that a bias toward an extreme opinion is introduced whenever two individuals interact and form a common decision. As a simple proxy for hierarchical social structures, we introduce a two-step decision making process in which in the second step groups of like-minded individuals are replaced by representatives once they have reached local consensus, and the representatives in turn form a collective decision in a downstream process. We find that the introduction of such a hierarchical decision making structure can improve consensus formation, in the sense that the eventual collective opinion is closer to the true average of individual opinions than without it. In particular, we numerically study how the size of groups of like-minded individuals being represented by delegate individuals affects the impact of the bias on the final population-wide consensus. These results are of interest for the design of organizational policies and the optimization of hierarchical structures in the context of group decision making.
EFFECT OF CARBONIZATION TEMPERATURE ON DIELECTRIC AND MICROWAVE ABSORBING PROPERTIES OF COBALT DOPED MESOPOROUS CARBON COMPOSITES
Authors: LIAN QIAN , WANG LIUDING , WU HONGJING , WU HAO
Published: December 2013

Co doped mesoporous carbon composites (MC– Co ) have been synthesized at different carbonization temperatures via evaporation-induced multicomponent co-assembly strategy. The nanostructures and chemical compositions of MC– Co composites were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction analysis (XRD), etc. Their electromagnetic and microwave absorption properties were investigated in the frequency ranging from 2 GHz to 18 GHz. By the measurement of electromagnetic parameters and theoretical simulation of reflection loss (RL), the results showed that the minimum RL value of the optimum composite MC– Co -800 reached up to -41.9 dB at 13.5 GHz with a thickness of only 1.80 mm, and the effective absorption bandwidth (< -10 dB) is 4.4 GHz (from 11.4 GHz to 15.8 GHz). This work demonstrated that the optimum carbonization temperature of the obtained composites is 800°C, which is critical to its electromagnetic properties. The excellent microwave absorption properties can be attributed to dielectric loss, Ohmic loss, and characteristic impedance matching. Therefore, the as-synthesized composites could be acted as a candidate of microwave absorber, especially for the light weight demand.
COST CONCEPTS FOR CLIMATE CHANGE MITIGATION
Authors: PALTSEV SERGEY , CAPROS PANTELIS
Published: December 2013

Major cost concepts used for evaluation of carbon policy are considered, including change in GDP, change in consumption, change in welfare, energy system cost, and area under marginal abatement cost (MAC) curve. The issues associated with the use of these concepts are discussed. We use the results from the models that participated in the European Energy Modeling Forum (EMF28) study to illustrate the cost concepts. There is substantial variability in the estimates of costs between the models, with some models showing substantial costs and some models reporting benefits from mitigation in some scenarios. Because impacts of a policy are evaluated as changes from a reference scenario, it is important to define a reference scenario. MAC cost measures tend to exclude existing distortions in the economy, while existing energy taxes and subsidies are substantial in many countries. We discuss that carbon prices are inadequate measures of the policy costs. We conclude that changes in macroeconomic consumption or welfare are the most appropriate measures of policy costs.