bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of Major Aspects of Wind Energy Generation
Authors: Hobbs William B.
Published: July 2009

The objective of this project was to perform an analysis of all of the major aspects of implementing electrical power generation using wind energy in a specific location. The project consisted of three main sections: location selection, turbine modeling and selection, and an economic analysis of the potential project as a whole. A limiting factor for a location was the availability of adequate wind speed data for analysis of the area’s potential. With these criteria, several locations were considered, and the Dominican Republic was selected because of high wind energy potential as well as high demand for electricity. There were several regions of the country with class 4 winds [1], and the average cost of electricity was very high at $0.15/kWh [2]. For the modeling and design of a wind turbine, a program named PROPID was used, which is a tool that takes design and wind parameters and returns simulated data such as power curves. The software was first validated for known configurations, to show the accuracy of the program, and it was then used to iteratively design new turbine configurations. The design of a popular 1300 kW commercial turbine, the Nordex N60, was scaled down to produce 1000 kW, and then gradually redesigned to increase the ratio of the power output to the surface area of the turbine, which was termed the design-factor, which would help to increase profitability of the turbine. The design-factor was increased from 320.9 for the original design to 466.2 for the final design. The final portion of the project was an economic analysis of a proposed wind farm. A software tool called HOMER was used, as well as Microsoft Excel’s internal rate of return function to calculate the long-term return of the project. Initial and annual costs were estimated based on available data for existing projects, and a 10 MW, 20 year life-span project was simulated using the newly designed turbine. Total levelized cost of energy was found to be between $0.042 and $0.057/kWh, depending on actual costs, and the overall annual return on investment in the project was calculated to be between a very conservatively determined value of 9.1% and a more general value of 12.9%. These values are limited in accuracy, and a more detailed study would be required prior to further project consideration, however they do indicate that this area is highly likely to have profitable wind energy resources.
Using Staged Compression to Increase the System Efficiency of a Coal Based Gas Turbine Fuel Cell Hybrid Power Generation System With Carbon Capture
Authors: VanOsdol John G. , Gemmen Randall , Parsons Edward
Published: July 2009

This paper examines two coal-based hybrid configurations that employ separated anode and cathode streams for the capture and compression of CO2. One system uses a single compressor to compress and partially preheat the cathode air flow. The second system replaces the single compressor with a two stage compression process with an intercooler to extract heat between the stages, and to reduce the work that is required to compress the air flow in the cathode stream. Calculations are presented for both systems with and without heat recuperation. For the single compressor system with heat recuperation the hybrid system assumes the form of a recuperated Brayton cycle; when the recuperator is not present the hybrid system assumes the form of a standard Brayton cycle. The calculation results show that an increase of 2.2% in system efficiency was obtained by staging the compression for these cycles.
Performance of Nozzle, Venturi, and Orifice Meters Relative to Extrapolation Criteria
Authors: Nystrom James B. , Stacy Phillip S.
Published: July 2009

Flow meter performance is described by the dimensionless numbers of discharge coefficient and Reynolds number. To achieve the best flow measurement uncertainty, meters are tested (calibrated) to determine the discharge coefficient behavior versus Reynolds number (magnitude and slope). Various meter designs have differing Reynolds number dependence. In many cases calibration laboratories can not achieve the Reynolds number at which the flow meter will operate. This deficiency is usually due to fluid properties (density and viscosity) at operating conditions being considerably different than those in a water-based calibration laboratory. Testing using fluids such as natural gas may increase the achievable Reynolds number but it is difficult to achieve the low uncertainty of the discharge coefficient possible in a water calibration due to the additional uncertainty of the expansion factor required with compressible fluids and the problems associated with gravimetric measurements of compressible fluids. In some power industry applications, operating Reynolds numbers may be an order of magnitude higher than can be achieved during calibration. Therefore, calibration data must be used to infer the discharge coefficient at operating conditions (Reynolds number), defining extrapolation. In Code tests, minimum flow measurement uncertainty is the objective and the uncertainty must be estimated. The largest uncertainty component in a flow measurement application usually is the discharge coefficient, which is dependent on the care of fabrication, the calibration data, and the extrapolation process. Measured discharge coefficients of Throat Tap Nozzles, Venturi meters Wall Tap Nozzles, and Orifice Meters are compared to predictive equations.
Investigating a Power-Obsorber Wave Energy Converter
Authors: Rahmati M. T. , McCabe A. P. , Aggidis G. A. , Chaplin R. V.
Published: July 2009

This paper presents the assessment of the optimum performance of a wave energy converter. In this device which is hinged at the seabed, wave forces act on the face of a collector body, carried on an arm that rotates about a fixed horizontal axis. The collector body oscillates at about the frequency of the ocean swell generating high power from this relatively small and economical device. The performance of the device is investigated using numerical hydrodynamic analysis and the wave tank experiment for a model at a nominal scale of 1/100. Also the optimum mean power output of the device in irregular wave climates is assessed. A first-order method is used to calculate the mean power spectrum of the device in waves of dissimilar spectra. It is shown that the choice of tuning period has a major effect on the power absorbed, hence on the power output.
Eliminating Steam Blow Piping Overcleaning During Power Plant Startup
Authors: Jarvis Julie M. , Vieiria Allen T. , Babel Paul J. , Kochis Paul J.
Published: July 2009

This paper investigates and justifies the use of a minimum necessary cleaning force ratio or cleaning factor for steam blows. Steam line blowing is an operational cleaning method used to clean steam piping and reheaters prior to turbine powering for steam power plants. The steam blows remove weld bead deposits, slag, debris, surface scale, and other foreign materials which could be carried into the steam turbines and damage the turbine blades during normal plant operation. Piping is blown, bypassing the turbine, with sufficient boiler pressure to ensure the dynamic pressure throughout the piping is greater than would be experienced during all plant operating conditions. By providing flow rates corresponding to the maximum service condition for any given section of piping, there will be sufficient kinetic energy to ensure complete removal of any impurities from the pipe. Historically, the required steam blow pressures are calculated to achieve a cleaning force ratio of 1.2. Cleaning Force Ratio (CFR) or Cleaning Factor (CF) is an industry-accepted factor that quantifies the ratio of required dynamic pressure for cleaning to maximum dynamic pressure experienced during system operation. For CFRs, the turbine vendors tend to have guidelines or ranges rather than definitive acceptance criteria. It is usually left up to the commissioning engineer, the Project Startup Manager and Owner to determine what is necessary for final acceptance. It is desirable to reduce the required minimum blowout pressure and flow rate to facilitate plant startup. By reducing the required minimum blowout pressure and flow rate, permanent plant equipment and temporary steam blow piping wear can be reduced and over cleaning avoided. Further, time between steam blows can be reduced. This paper examines the CFR guidelines for various turbine vendors and justifies reducing the CFR from 1.2 to 1.0. Advantages of the use of a minimum necessary CFR include reduced required steam blow pressures which result in safer steam blows, and less expensive temporary steam blow piping. Use of a minimum necessary CFR will still maintain the effectiveness of the steam blow.
Condenser Tube Examination Using Acoustic Pulse Reflectometry
Authors: Amir Noam , Barzelay Oded , Yefet Amir , Pechter Tal
Published: July 2009

Acoustic Pulse Reflectometry (APR) has been applied extensively to tubular systems in research laboratories, for purposes of measuring input impedance, bore reconstruction, and fault detection. Industrial applications have been mentioned in the literature, though they have not been widely implemented. Academic APR systems are extremely bulky, often employing source tubes of six meters in length, which limits their industrial use severely. Furthermore, leak detection methods described in the literature are based on indirect methods, by carrying out bore reconstruction and finding discrepancies between the expected and reconstructed bore. In this paper we describe an APR system designed specifically for detecting faults commonly found in industrial tube systems: leaks, increases in internal diameter caused by wall thinning, and constrictions. The system employs extremely short source tubes, on the order of 20cm, making it extremely portable, but creating a large degree of overlap between forward and backward propagating waves in the system. A series of algorithmic innovations enable the system to perform the wave separation mathematically, and then identify the above faults automatically, with a measurement time on the order of 10 seconds per tube. We present several case studies of condenser tube inspection, showing how different faults are identified and reported.
Inspections of Tread Damaged Wheelsets
Authors: Cummings Scott M. , Lauro Don
Published: July 2009

Inspections of 163 wheelsets conducted by the Wheel Defect Prevention Research Consortium (WDPRC) have produced critical information in identifying the high-level root causes of tread damage. While the overall wheel tread damage problem appears to be split fairly evenly between shelling and spalling, the type of tread damage on a wheelset is strongly linked to the type of car from which it was removed. Coal car wheels, which generally run in heavy axle load, high-mileage service with minimal yard handling, are almost exclusively subject to shelling damage with little spalling damage. On the other hand, mixed freight cars, such as tank cars and covered hopper cars, tend to run in lower mileage service with more yard handling, resulting in fewer loading cycles under lighter stress and more frequent use of hand brakes. Not surprisingly then, wheels from these types of cars were observed to have a mix of spalling and shelling damage, with spalling being the predominant damage mechanism. Nearly every high impact wheel (HIW) inspected showed either spalling, shelling, or some combination of the two. As expected, wheel impact load detector (WILD) readings and radial tread run out data were found to be related. Rim thickness deviations and rim lateral face deviations were not found to be important contributors to shelling. The lateral tread location of radial run-out deviations and crack bands could be an important clue in discovering the root cause of shelling. Radial run-out data and crack band location data shows that shelling damage is most prevalent outboard of the tapeline. This is the expected wheel/rail contact position of a wheel in the lead wheelset position of a truck, while riding on the low (inside) rail of a curve. Many of the wheels that were removed for wear causes were found to have noncondemnable shelling and spalling, indicating that tread damage is more prevalent than repair records would indicate.
Finite Element Analyses of Railroad Tank Car Head Impacts
Authors: Tang Y. H. , Yu H. , Gordon J. E. , Jeong D. Y.
Published: July 2009

This paper describes engineering analyses of a railroad tank car impacted at its head by a rigid punch. This type of collision, referred to as a head impact, is examined using dynamic, nonlinear finite element analysis (FEA). Commercial software packages ABAQUS and LS-DYNA are used to carry out the nonlinear FEA. The sloshing response of fluid and coupled dynamic behavior between the fluid inside the tank car and the tank structure are characterized in the model using both Lagrangian and Eulerian mesh formulations. The analyses are applied to examine the structural behavior of railroad tank cars under a generalized head impact scenario. Structural behavior is calculated in terms of forces, deformations, and puncture resistance. Results from the two finite element codes are compared to verify this methodology for head impacts. In addition, FEA results are compared to those from a semi-empirical method.
Effect of Residual Stress, Temperature and Adhesion on Wheel Surface Fatigue Cracking
Authors: Stone Daniel H. , Cummings Scott M.
Published: July 2009

The Wheel Defect Prevention Research Consortium (WDPRC) conducted an analysis pertaining to the fatigue cracking of wheel treads by incorporating the effects of residual stresses, temperature, and wheel/rail contact stress. Laboratory fatigue tests were conducted on specimens of wheel tread material under a variety of conditions allowing the analysis to properly account for the residual stresses accumulated in normal operating conditions. Existing literature was used in the analysis in consideration of the effects of contact stress and residual stress relief. This project was performed to define a temperature range in which the life of an AAR Class C wheel is not shortened by premature fatigue and shelling. Wayside wheel thermal detectors are becoming more prevalent on North American railroads as a means of identifying trains, cars, and wheels with braking issues. Yet, from a wheel fatigue perspective, the acceptable maximum operating temperature remains loosely defined for AAR Class C wheels. It was found that residual compressive circumferential stresses play a key role in protecting a wheel tread from fatigue damage. Therefore, temperatures sufficient to relieve residual stresses are a potential problem from a wheel fatigue standpoint. Only the most rigorous braking scenarios can produce expected train average wheel temperatures approaching the level of concern for reduced fatigue life. However, the variation in wheel temperatures within individual cars and between cars can result in temperatures high enough to cause a reduction in wheel fatigue life.
Simulation of Solidification of a 19 Inch Diameter, Double Length Steel Ingot
Authors: Dedmon Steven L. , Dutler Shelly , Pilch James , Galbraith Jay
Published: July 2009

Identifying the process variables that are important to ensuring the production of high quality ingots intended to make railway wheels and axles can be done through costly experimentation, or by numerical simulations. Using MAGMASOFT® software, we created a base model. The base model was validated in three different ways, using results from production to compare against the simulation. Process parameters were then varied to determine if the changes were beneficial or detrimental to conditions such as porosity, pipe and segregation.
Rail RCF and the Effects of Different Wheel Profiles
Authors: Mehrgou Mehdi , Nasr Asghar
Published: July 2009

Wheel lateral profile has considerable effects on the wheel/rail dynamic interactions such as the shape and size of the contact area, instantaneous rolling radius and contact forces. Theses themselves have indirectly important roles on the rolling contact fatigue (RCF) which is known to be the main reason for large portion of rail maintenance costs. In this study the wheel/rail dynamic interaction of an Iranian railway passenger wagon under three different wheel profiles are investigated using ADAMS\Rail commercial simulation software. The dynamic simulation results regarding contact load and contact features of the wheel and rail are used for fatigue analysis to calculate RCF damage to the rail using reliable damage criteria reported in the literature. The two major parameters having serious roles on the RCF are believed to be the contact stress and the tangential force at the contact patch. These parameters are obtained from vehicle dynamic simulation studies. This paper describes and compares the effects of three different wheel profiles known as S1002, P8 and IR1002 on the rail RCF in both the curved and tangent sections of a track. The primary results clearly identify the effects of wheel profile on the RCF.
A Percolation Based Micromechnical Constitutive Model for Flexible Piezoelectric Paint
Authors: Li Xin , Zhang Yunfeng
Published: July 2009

A percolation theory based micromechanics model is proposed in this paper to describe the elastoelectric properties of flexible piezoelectric paint. Piezoelectric paint consists of tiny piezoelectric ceramic particles randomly dispersed in a polymer matrix and therefore belongs to the “0–3” piezoelectric composite. Because of its ease of application, piezoelectric paint can be readily fabricated into sensing element with complex patterns. To guide the sensor design, a micromechanics model for describing the electromechanical properties of piezoelectric paint is proposed. The focus of this research is given to piezoelectric paint with a piezoelectric ceramic volume fraction ranging from 35% to 65%, for which some of the active particles form 1–3 connectivity, leading to higher piezoelectric activity than previous models for piezoelectric 0–3 composites predict. Percolation theory is used to model the quick increase of piezoelectric activity after a threshold level of piezoelectric ceramic particle volume fraction is exceeded in the piezoelectric paint. The effect of piezoelectric ceramic volume fraction on the electromechanical properties of piezoelectric paint is first examined. The proposed model for piezoelectric paint considers the effect of air void contents and poling field on the elastoelectric properties of piezoelectric paint. The parameters of the present model are calibrated with experimental data.
Performance of Embedded Multi-Frequency Communication Devices in Smart Composite Structures
Authors: Sulic E. , Pell B. , John S. , Gupta Rahul K. , Rowe W. , Ghorbani K. , Zhang K.
Published: July 2009

Lately, there has been an increased demand for vehicle manufacturers to incorporate a large number of communication, security, guidance and entertainment devices in their new vehicle models. In recent decades, the list has expanded from the AM and FM radio antennas to include GPS, mobile phone, collision avoidance radar, Digital Radio and Digital TV antennas. In addition, new technologies such as vehicle to vehicle and vehicle to road side communication are being implemented at 5.9 GHz in the next generation of vehicles. In the past the AM/FM antenna was typically a mast antenna protruding from the vehicle’s exterior, recently however, the trend has been to limit the visibility of vehicular antennas as much as possible to improve vehicle design and aerodynamics. This has lead to integration of antennae so that they become a seamless part of the vehicle structure. This paper reports on a parametric study of embedding an antenna in a polymeric composite substrate in relation to several material processing and coating parameters.
Post-Buckled Precompressed Techniques in Adaptive Aerostructures: An Overview
Authors: Vos Roelof , Barrett Ron
Published: July 2009

An overview of the development and application of postbuckled precompressed (PBP) piezoelectric actuators is presented. It has been demonstrated that PBP actuators outperform conventional piezoelectric actuators by relying on axial compression to counter the inherent stiffness in the actuator element. In doing so the mechanical work output has been shown to increase three-fold compared to conventional bimorph actuators. Actuator stroke has been demonstrated to increase up to 300% without compromising the blocked force capability. This results in an expansion of the design space of piezoelectric bender elements and makes them excellent candidates for substituting conventional electromechanical flight control actuators. Successful application of PBP elements can be found in unmanned aerospace systems ranging from subscale vertical-take-off-and-landing vehicles to supersonic missile fins. With respect to conventional electromechanical servoactuators it is demonstrated that PBP actuator elements induce a lower systems weight fraction, a substantially higher bandwidth, and an order of magnitude lower power consumptions and part count.
Design and Proof-of-Concept Validation of a Latched Arch Active Seal
Authors: Toma Monica , Luntz Jonathan , Brei Diann , Alexander Paul W. , Browne Alan L. , Johnson Nancy L.
Published: July 2009

Seals are integral to many industries such as aerospace, marine, oilfield and automotive. A key performance metric for seal quality is quantified by the normal force between the seal and contact surface. Many applications have conflicting requirements on the normal force depending on the operational state. For example in panel closures, to ease engagement of the seal the normal force (closing force) should be small; whereas, to maintain a high-quality seal the normal force (sealing force) should be large. While there is an abundance of seal technologies, there still exists a need for adaptable seals that can better accommodate the conflicting demands of multiple operational states and variations in application platforms. This paper introduces an active seal which controls normal force through modification of the structure of a rubber arch seal. While there are several options for actuation, this new technology is modeled, fabricated and experimentally validated utilizing a Shape Memory Alloy web actuation scheme. Finite element models provide a basis for a parametric study from which design guidelines are derived. The technology and supporting models/processes are demonstrated for an automotive panel closure successfully reducing the closing force by almost 50% while simultaneously increasing the sealing force by over 30%.
A Preliminary Study of Piezoelectric Vibration Energy Harvester for Vibration Condition Monitoring Applications of Rotating Machinery
Authors: Adachi Kazuhiko , Tanaka Tohru
Published: July 2009

Rotating machinery is widely used in the industrial plant, for example, power plant, chemical plant, mass-production plant and so on. In order to ensure safety operation of the rotating machinery, vibration condition monitoring of the machinery can play a crucial role. In this study, the cantilever type of vibration energy harvester is designed for vibration condition monitoring applications of rotating machinery. The mechanical resonant frequency of piezoelectric bimorph cantilever will be tuned to the rotating speed of the machinery. Recently, new d31 type Macro-Fiber Composite (MFC) can be commercially available. Due to the d31 configuration, electrical impedance of new MFC is much smaller than that of previous d33 type MFC. This study experimentally compares the ability two types of MFC, d31 and d33 configurations, to generate electrical energy when subjected to mechanical vibration.
Numerical Tool Based on Finite Element Method for SMA Structures Design
Authors: Chemisky Yves , Duval Arnaud , Piotrowski Boris , Ben-Zineb Tarak , Patoor Etienne
Published: July 2009

A macroscopic model for SMA materials is proposed. Thermodynamics considerations, strain mecanisms and numerical implementation in a commercial code are presented here. This numerical tool is used to design structures, such elastomer/SMA composites ribbons, and by adding scale transition schemes, this model is able to predict the behavior of allied SMA, like commercial Ni47Ti44Nb9. Simulations in these two cases are compared to experimental datas.
Transient Thermodynamic Modelling and Experimental Validation of an Antagonistic SMA Actuator
Authors: Pathak Anupam , Brei Diann , Luntz Jonathan
Published: July 2009

Modern developments in Shape Memory Alloys (SMA) has positioned the material as an attractive alternative actuation for high yield, low cost industries which stand to benefit from the materials simple form, light weight, and high energy densities. However, the speed and predictability still remain as a barrier to its acceptance and usage. The robotics community has shown promising results with antagonistic actuation architectures to increase the cyclic speed and produce controlled motions; however, such control-based approaches generally require sensing and feedback implementations and tuning that are undesirable for high production products. This paper presents a simple but effective physically-based thermodynamic model for generic antagonistic actuation architecture. The model is derived from three sets of equations: differential equations describing the thermomechanical phase transformation behavior of the material, compatibility equations specific to the antagonistic configuration relating stresses and strains in the two wires to each other, and heat transfer equations involving the thermal properties of both the environment and the wire material. This model takes into consideration several key-aspects of real devices such as the wires becoming slack or localalized boiling conditions. This model was experimentally validated and studied under a range of conditions including variations in driving frequency (0.3–10 Hz), duty cycle (10%–45%), amplitude (50%–100% transformation), and wire diameter (8–20 mil). The correlation over these widely varying conditions indicates the model’s accuracy and potential for use in the design process of future antagonistic actuators and their controllers for industrial applications.
Perspirable Skin: A Multifuctional Material System for Self-Cooling
Authors: Oguz Basak , Sun Li , Kwon Patrick
Published: July 2009

Utilizing the negative thermal expansion property of ZrW2O8, Perspirable skin, an autonomous cooling system, was designed for externally heated surfaces of reentry vehicles such as Space Shuttle. In this material system, several ZrW2O8 pegs are shrink-fit into the Reinforced Carbon-Carbon composite (RCC) skin. At working conditions, a gap or interference forms between the two materials and the compressed gas within the vehicle can blow out through the gap. The atmospheric air, rather than contributing to the frictional heat between air and skin, is mixed with the cold compressed air over the surface. Due to the nonlinear thermoelastic properties within the operating temperatures, Finite Element Analysis was used to design the geometry of the ZrW2O8 pegs and the best fiber arrangement of the RCC for this material system. The geometry of the peg with a larger radius at the top surface and a smaller radius at the bottom part ensures the secure contact of two materials at the working condition. The design with the frustum of a cone shaped top offered a better and shorter route for the coolant gas to be passed. The best type of RCC is found to be 3D woven orthogonal.
Single Crystal PMN-PT Electric Fatigue and Fracture Behavior
Authors: Gorzkowski E. P. , Pan M.-J. , DeGiorgi V. G. , Wimmer S. A. , Qidwai M. A. Siddiq
Published: July 2009

Piezoelectric single crystals are being incorporated into many new devices because of the superior properties they exhibit. Not much attention has been paid to the mechanical robustness of these materials. In this work the fracture and fatigue behavior of Pb(Mg1/3Nb2/3)O3−29 mol% PbTiO3 (PMN-29PT) is studied. Vickers indentation result show that the KIC of this material is 0.3 MPa m1/2. Intentional defects from the indentation show that the <100> direction is the weakest direction and that electrical fatigue is fastest in the <100> direction. By looking at the hysteresis behavior of this material before and after the fatigue runs, the material ages over time.
Analysis and Design of Smart Electromagnetic Structures
Authors: Ramesh Prashanth , Washington Gregory
Published: July 2009

Use of ferroelectric materials to improve antenna performance is an area of active research. Applying an electric field across a ferroelectric used as the dielectric in an antenna enables tuning the antenna performance. Ferroelectrics also have coupled electromechanical behavior due to which it is sensitive to mechanical strains and fluctuations in ambient temperature. Use of ferroelectrics in antenna structures, especially those subject to mechanical and thermal loads, requires knowledge of the phenomenological relationship between the ferroelectric properties of interest (especially dielectric permittivity) and the external physical variables, viz. electric field(s), mechanical strains and temperature. To this end, a phenomenological model of ferroelectric materials based on the Devonshire thermodynamic theory is presented. This model is then used to obtain a relationship expressing the dependence of the dielectric permittivity on the mechanical strain, applied electric field and ambient temperature. The relationship is compared with published experimental data and other models in literature. Subsequently, a relationship expressing the dependence of antenna performance on those physical quantities is described.
FE Analysis of SMA-Based Bio-Inspired Bone-Joint System
Authors: Yang Shibin , Seelecke Stefan
Published: July 2009

The application of shape memory alloys (SMA) as actuators in a smart structure is a quickly developing field. The particular focus of this paper is on the aspects of modeling and simulation of a bio-inspired bone-joint system using the finite element method (FEM). The actuation of a typical bat’s humerus-radius system is effected by means of micro-scale actuator wires performing like metal muscles when heated. In addition, the elbow is modeled as a flexible hinge using superelastic SMA wires. This system serves as a first step towards the design of a flapping wing to propel the next generation Micro Aerial Vehicle (MAV). In this bio-inspired bone-joint-system, the humerus and radius were modeled as standard elastic beams. Shape memory alloys were employed in two different ways: one is an SMA wire in the martensite phase, the other is an SMA beam in the austenite phase. The SMA wires work as muscles to actuate the bio-system due to contraction upon electric heating. The SMA beams work as flexible joints due to their superelastic character. In this work, the modeling and simulation of the adaptive structure was implemented in COMSOL Multiphysics. The active material model used is based on the Muller-Achenbach-Seelecke shape memory alloy model. The paper has a particular focus on the implementation of the SMA model into COMSOL combining general PDE modes with structural mechanics truss and beam elements. COMSOL has been chosen because of its natural way of handling multi-physics situations such as the thermomechanical coupling relevant for the SMA application.
Dependence of Mouse Embryonic Stem Cells on Threonine Catabolism
Authors: Wang Jian , Alexander Peter , Wu Leeju , Hammer Robert , Cleaver Ondine , McKnight Steven L.
Published: July 2009

Threonine Required

Embryonic stem (ES) cells divide rapidly, raising the possibility that they might exist in a metabolic state that facilitates rapid growth. By monitoring the abundance of common metabolites in mouse ES cells,

Wang
et al.

(p.
435
; published online 9 July) found altered levels of metabolites involved in carbon metabolism. Measurement of messenger RNA levels revealed unusually high expression of the gene encoding threonine dehydrogenase. In addition, in growth experiments, mouse ES cells were critically dependent on the amino acid threonine.
The Formation of Population III Binaries from Cosmological Initial Conditions
Authors: Turk Matthew J. , Abel Tom , O'Shea Brian
Published: July 2009

Genesis of Binary Stars

Numerical simulations of collapsing clouds of primordial gas indicate that the first luminous objects to form in the universe were isolated massive stars.

Turk
et al.

(p.
601
, published online 9 July) now show that it is possible for single primordial clouds to break up into two dense cores. Three-dimensional calculations, which follow the evolution of primordial gas (composed of hydrogen and helium, with traces of deuterium and lithium) and dark matter starting from realistic, cosmological initial conditions, suggest that these cores may evolve to form binary star systems.
Positive Selection of Tyrosine Loss in Metazoan Evolution
Authors: Tan Chris Soon Heng , Pasculescu Adrian , Lim Wendell A. , Pawson Tony , Bader Gary D. , Linding Rune
Published: July 2009

Cataloging Kinase Targets

Protein phosphorylation is a central mechanism in the control of many biological processes (see the Perspective by

Collins

). It remains a challenge to determine the complete range of substrates and phosphorylation sites altered by a kinase like cyclin-dependent kinase 1 (Cdk1), which controls cell division in yeast.

Holt
et al.

(p.
1682
) engineered a strain of yeast to express a modified Cdk1 molecule that could be inhibited by a specific small-molecule inhibitor. The range of Cdk1-dependent phosphorylation was assessed by quantitative mass spectrometry, which revealed many previously uncharacterized substrates for Cdk1. In addition to phosphorylation on serine and threonine residues, which appears to be evolutionarily ancient, tyrosine phosphorylation occurs primarily in multicellular organisms.

Tan
et al.

(p.
1686
, published online 9 July) compared the overall presence of tyrosine residues in human proteins (which are frequently phosphorylated) and in yeast proteins (which are not). Loss of tyrosine residues has occurred during evolution, presumably to reduce adventitious tyrosine phosphorylation.
SPECTRAL PROPERTIES AND LINEAR STABILITY OF SELF-SIMILAR WAVE MAPS
Authors: DONNINGER ROLAND , AICHELBURG PETER C.
Published: July 2009

We study co-rotational wave maps from (3 + 1)-Minkowski space to the three-sphere S3. It is known that there exists a countable family {fn} of self-similar solutions. We investigate their stability under linear perturbations by operator theoretic methods. To this end we study the spectra of the perturbation operators, prove well-posedness of the corresponding linear Cauchy problem and deduce a growth estimate for solutions. Finally, we study perturbations of the limiting solution which is obtained from fn by letting n → ∞.
SUBSONIC FLOWS FOR THE FULL EULER EQUATIONS IN HALF PLANE
Authors: CHEN JUN
Published: July 2009

We study the subsonic flows governed by full Euler equations in the half plane bounded below by a piecewise smooth curve asymptotically approaching the x1-axis. Nonconstant conditions in the far field are prescribed to ensure the real Euler flows. The Euler system is reduced to a single elliptic equation for the stream function. The existence, uniqueness, and asymptotic behaviors of the solutions for the reduced equation are established by the Schauder fixed point argument and some delicate estimates. The existence of subsonic flows for the original Euler system is proved based on the results for the reduced equation, and their asymptotic behaviors in the far field are also obtained.
Gas hydrate drilling transect across northern Cascadia margin - IODP Expedition 311
Authors: Riedel M. , Collett T. , Malone M. J. ,   IODP Expedition 311 Scientists
Published: July 2009

A transect of four sites (U1325, U1326, U1327 and U1329) across the northern Cascadia margin was established during Integrated Ocean Drilling Program Expedition 311 to study the occurrence and formation of gas hydrate in accretionary complexes. In addition to the transect sites, a fifth site (U1328) was established at a cold vent with active fluid flow. The four transect sites represent different typical geological environments of gas hydrate occurrence across the northern Cascadia margin from the earliest occurrence on the westernmost first accreted ridge (Site U1326) to the eastward limit of the gas hydrate occurrence in shallower water (Site U1329). Expedition 311 complements previous gas hydrate studies along the Cascadia accretionary complex, especially ODP Leg 146 and Leg 204 by extending the aperture of the transect sampled and introducing new tools to systematically quantify the gas hydrate content of the sediments. Among the most significant findings of the expedition was the occurrence of up to 20 m thick sand-rich turbidite intervals with gas hydrate concentrations locally exceeding 50% of the pore space at Sites U1326 and U1327. Moreover, these anomalous gas hydrate intervals occur at unexpectedly shallow depths of 50–120 metres below seafloor, which is the opposite of what was expected from previous models of gas hydrate formation in accretionary complexes, where gas hydrate was predicted to be more concentrated near the base of the gas hydrate stability zone just above the bottom-simulating reflector. Gas hydrate appears to be mainly concentrated in turbidite sand layers. During Expedition 311, the visual correlation of gas hydrate with sand layers was clearly and repeatedly documented, strongly supporting the importance of grain size in controlling gas hydrate occurrence. The results from the transect sites provide evidence for a structurally complex, lithology-controlled gas hydrate environment on the northern Cascadia margin. Local shallow occurrences of high gas hydrate concentrations contradict the previous model of gas hydrate formation at an accretionary prism. However, long-lived fluid flow (part of the old model) is still required to explain the shallow high gas hydrate concentrations, although it is most likely not pervasive throughout the entire accretionary prism, but rather localized and focused by the tectonic processes. Differences in the fluid flow regime across all of the transect drill sites indicate site-specific and probably disconnected (compartmented) deeper fluid sources in the various parts of the accretionary prism. The data and future analyses will yield a better understanding of the geologic controls, evolution and ultimate fate of gas hydrate in an accretionary prism as an important contribution to the role of gas hydrate methane gas in slope stability and possibly in climate change.
Hydrate occurrences in the Namibe Basin, offshore Namibia
Authors: Swart Roger
Published: July 2009

Seismic data has long suggested the presence of methane hydrates offshore Namibia. The seismic data shows the presence of well-developed bottom-simulating reflectors which can be mapped over a large area. A recent seabed coring programme has confirmed the presence of hydrates in the Namibe Basin. The hydrates appear to be associated with slump features and are a drilling hazard as well as a potential resource. The methane hydrate appears to originate from both biogenic and thermogenic sources.
Interaction between muscle temperature and contraction velocity affects mechanical efficiency during moderate-intensity cycling exercise in young and older women
Authors: Bell Martin P. , Ferguson Richard A.
Published: July 2009

The effect of elevated muscle temperature on mechanical efficiency was investigated during exercise at different pedal frequencies in young and older women. Eight young (24 ± 3 yr) and eight older (70 ± 4 yr) women performed 6-min periods of cycling at 75% ventilatory threshold at pedal frequencies of 45, 60, 75, and 90 rpm under control and passively elevated local muscle temperature conditions. Mechanical efficiency was calculated from the ratio of energy turnover (pulmonary O2uptake) and mechanical power output. Overall, elevating muscle temperature increased ( P < 0.05) mechanical efficiency in young (32.0 ± 3.1 to 34.0 ± 5.5%) and decreased ( P < 0.05) efficiency in older women (30.2 ± 5.6 to 27.9 ± 4.1%). The different effect of elevated muscle temperature in young and older women reflects a shift in the efficiency-velocity relationship of skeletal muscle. These effects may be due to differences in recruitment patterns, as well as sarcopenic and fiber-type changes with age.
A Comparison of the Effects of Voice Massage™ and Voice Hygiene Lecture on Self-Reported Vocal Well-Being and Acoustic and Perceptual Speech Parameters in Female Teachers
Authors: Leppänen Kirsti , Laukkanen Anne-Maria , Ilomäki Irma , Vilkman Erkki
Published: July 2009

This study compared the effects of Voice Massage™ (VM) and a voice hygiene lecture (VHL) on 60 female teachers. VM is a Finnish massage method which treats muscles related to voice production. All subjects attended the VHL (3 h). Half of them were randomly assigned to the VM group, the other half received only VHL. VM was given 5 times in 1-hour sessions at intervals of 1–2 weeks. At the beginning and end of the autumn school term, before and after a working day, (1) a 1-min reading sample was recorded at both the subject’s habitual loudness and loudly, (2) a prolonged phonation on [a:] was recorded at habitual speaking pitch and (3) a questionnaire on voice quality, ease or difficulty of phonation, and tiredness of the throat was completed. The reading samples were analysed for the fundamental frequency (F₀), equivalent sound level (Leq) and α-ratio [Leq (1–5 kHz) – Leq (50–1,000 Hz)]. The vowel samples were analysed for the F₀ and Leq, as well as for jitter and shimmer. The reading samples were also evaluated perceptually by 3 speech trainers. The mean F₀ and difficulty of phonation increased from the beginning to the end of the term in the VHL group (p = 0.026, p = 0.007, respectively). In the VM group, the perceived firmness of loud reading decreased (p = 0.026). The results suggest that VM may help in sustaining vocal well-being during a school term.
Segmental Duration in Parkinsonian French Speech
Authors: Duez Danielle
Published: July 2009

Objectives: The present study had 2 main objectives: (1) examine the effect of Parkinson’s disease (PD) on vowel and consonant duration in French read speech and (2) investigate whether the durational contrasts of consonants and vowels are maintained or compromised. Results: The data indicated that the consonant durations were shortened in Parkinsonian speech (PS), compared to control speech (CS). However, this shortening was consonant dependent: unvoiced occlusives and fricatives were significantly shortened compared to other consonant categories. All vowels were slightly longer in PS than in CS, however, the observed differences were below the level of significance. Despite significant shortening of some consonant categories, the general pattern of intrinsic duration was maintained in PS. There was slightly less agreement for vowels with the normal contrast of intrinsic durations, possibly because vowel durational contrasts are more sensitive to PD disorders. Conclusion: Most PD patients tended to maintain the intrinsic duration contrasts of both vowels and consonants, suggesting that low-level articulatory constraints operate in a similar way and with the same weight in PS and CS.
Transplant Glomerulopathy: Morphology, Associations and Mechanism
Authors: Fotheringham James , Angel Carole A. , McKane William
Published: July 2009

Transplant glomerulopathy (TG) is a lesion with specific morphology and strong evidence of an immune mechanism. The incidence of TG is approximately 20% by 5 years after transplantation. TG is characterized by proteinuria, hypertension and declining graft function. Appearances on light microscopy include thickened capillary walls and double contours, with reduplication or lamination of the glomerular basement membrane on electron microscopy. TG is associated with acute rejection, the antibody status before transplantation and de novo HLA antibodies. HLA class II and/or donor-specific antibodies incur additional risks. Desensitization protocols do not always prevent the development of TG in highly sensitized individuals. Associations between TG, past or current C4d and the presence of alloantibodies are recognised, however, C4d in the peri-tubular capillaries or glomeruli is not a prerequisite at the time of diagnosis. Clinical observation and animal models suggest that TG arises as a consequence of chronic endothelial cell (EC) injury by the humoral arm of the immune system. In some cases, this follows a period of EC accommodation after an episode of acute injury. Proposed treatments include augmentation of background immunosuppression, and trials of monoclonal therapies targeted at CD20-positive B cells are underway.
Y-Box Protein 1 Stimulates Mesangial Cell Proliferation via Activation of ERK1/2
Authors: Feng Quancheng , Huang Songming , Zhang Aihua , Chen Qiuxia , Guo Xirong , Chen Ronghua , Yang Tianxin
Published: July 2009

Aims: To investigate the effects of Y-box protein 1 (YB-1) on the mitogen-activated protein kinase pathway to ascertain which signaling pathway is involved in YB-1-induced mesangial cell (MC) proliferation. Methods: The rat MC line HBZY-1 was transfected with pcDNA3.1-YB-1. Cell proliferation was determined by [3H]thymidine incorporation, cell counting and cell-cycle analysis. The expression of cyclins was examined by real-time RT-PCR and immunoblotting analysis. Phosphorylation of c-Raf, MEK1/2, and ERK1/2 was detected by immunoblotting analysis. Results: MCs transfected with YB-1 showed an increased DNA synthesis and number of cells in the S and G2 phases of the cell cycle. The expression of cyclins (cyclin A2, cyclin D1, cyclin E and p27) was increased, while p21 levels were decreased. The expression levels of phosphorylated c-Raf kinase, MEK1/2 and the ERK1/2 proteins were elevated in MCs transfected with YB-1. YB-1-stimulated cell proliferation was blocked by U0126, a specific inhibitor of ERK1/2. ERK1/2 regulated YB-1 expression in MCs stimulated with TGF-β, an effect that was inhibited by U0126. Conclusions: YB-1 has an apparent stimulatory effect on c-Raf, MEK1/2, ERK1/2 and cell-cycle progression in MCs, after which activated ERK1/2 goes on to upregulate YB-1 expression and augment the proliferative effect of YB-1.
Microsurgical Technique of Simultaneous Pancreas/Kidney Transplantation in the Rat: Clinical Experience and Review of the Literature
Authors: Matevossian E. , Doll D. , Sinicina I. , Kern H. , Bald C. , Nährig J. , Stangl M. , Thorban S. , Hüser N.
Published: July 2009

Background: For experimental basic research, standardized transplantation models reflecting technical and immunologic aspects are necessary. This article describes an experimental model of combined pancreas/kidney transplantation (PKTx) in detail. Materials and Methods: Donor rats underwent en bloc pancreatectomy and nephrectomy. Revascularization was performed using the aorta with the superior mesenteric artery and the inferior vena cava with the portal vein. Exocrine drainage of the pancreas took place over a segment of the duodenum which was transplanted side-to-side to the jejunum. The kidney vessels were transplanted end-to-side. The ureter was anastomosed by patch technique. Postoperatively, serum parameters were monitored daily. Biopsies for histopathology were taken on days 5, 8 and 12. Results: All 12 recipients survived the combined PKTx without serious surgical complications. One thrombosis of the portal vein led to organ failure. Blood glucose levels were normal by the 3rd postoperative day. The transplanted duodenal segment showed slight villous atrophy, and the kidneys were well perfused without vascular complications. The anastomosis between ureter and bladder was leakproof. Conclusions: Excellent graft function and survival rates can be achieved due to simplified operation technique and short operation time. It may thus have high clinical relevance to immunologic issues within the scope of basic research.