bluuebunny/crossref_metadata_2025 huggingface dataset:
Annular Pressure Reduction During Primary Cementing
Authors: Zhou Desheng , Wojtanowicz Andrew K.
Published: September 2011

Annular pressure reduction during cementing is a major factor causing annular gas flow. It has been widely accepted and proven experimentally that the pressure reduction phenomenon results from the shear stress opposing downward motion of slurry undergoing volume reduction. The models that have been proposed to describe this process are based on the gel strength and shear stress developments in time and ignore system compressibility. They explain the pressure reduction process observed in the lab where compressibility of the system is very small. However, the models cannot explain the pressure reduction patterns observed on the field where compressibility is significant and the time-dependent effects of cement slurry volume loss significantly contributes to the process. The paper presents a mathematical model combining the effects of gel strength, volume reduction, and compressibility of cement slurry to describe pressure loss in the annular cement column. Results from the model, shown in the paper, compare very well with the data from the laboratory and field tests. Also, the simulated results explain discrepancies between the pressure loss patterns observed in the lab and field tests.
Cell-to-Cell Variability in Deformations Across Compressed Myoblasts
Authors: Slomka Noa , Gefen Amit
Published: September 2011

Many biological consequences of external mechanical loads applied to cells depend on localized cell deformations rather than on average whole-cell-body deformations. Such localized intracellular deformations are likely to depend, in turn, on the individual geometrical features of each cell, e.g., the local surface curvatures or the size of the nucleus, which always vary from one cell to another, even within the same culture. Our goal here was to characterize cell-to-cell variabilities in magnitudes and distribution patterns of localized tensile strains that develop in the plasma membrane (PM) and nuclear surface area (NSA) of compressed myoblasts, in order to identify resemblance or differences in mechanical performances across the cells. For this purpose, we utilized our previously developed confocal microscopy-based three-dimensional cell-specific finite element modeling methodology. Five different C2C12 undifferentiated cells belonging to the same culture were scanned confocally and modeled, and were then subjected to compression in the simulation setting. We calculated the average and peak tensile strains in the PM and NSA, the percentage of PM area subjected to tensile strains above certain thresholds and the coefficient of variation (COV) in average and peak strains. We found considerable COV values in tensile strains developing at the PM and NSA (up to ∼35%) but small external compressive deformations induced greater variabilities in intracellular strains across cells compared to large deformations. Interestingly, the external deformations needed to cause localized PM or NSA strains exceeding each threshold were very close across the different cells. Better understanding of variabilities in mechanical performances of cells—either of the same type or of different types—is important for interpreting experimental data in any experiments involving delivery of mechanical loads to cells.
Changes in the Tangent Modulus of Rabbit Septal and Auricular Cartilage Following Electromechanical Reshaping
Authors: Lim Amanda , Protsenko Dmitry E. , Wong Brian J. F.
Published: September 2011

Transforming decades’ old methodology, electromechanical reshaping (EMR) may someday replace traditionally destructive surgical techniques with a less invasive means of cartilage reshaping for reconstructive and esthetic facial surgery. Electromechanical reshaping is essentially accomplished through the application of voltage to a mechanically deformed cartilage specimen. While the capacity of the method for effective reshaping has been consistently shown, its associated effects on cartilage mechanical properties are not fully comprehended. To begin to explore the mechanical effect of EMR on cartilage, the tangent moduli of EMR-treated rabbit septal and auricular cartilage were calculated and compared to matched control values. Between the two main EMR parameters, voltage and application time, the former was varied from 2–8 V and the latter held constant at 2 min for septal cartilage, 3 min for auricular cartilage. Flat platinum electrodes were used to apply voltage, maintaining the flatness of the specimens for more precise mechanical testing through a uniaxial tension test of constant strain rate 0.01 mm/s. Above 2 V, both septal and auricular cartilage demonstrated a slight reduction in stiffness, quantified by the tangent modulus. A thermal effect was observed above 5 V, a newly identified EMR application threshold to avoid the dangers associated with thermoforming cartilage. Optimizing EMR application parameters and understanding various side effects bridge the gap between EMR laboratory research and clinical use, and the knowledge acquired through this mechanical study may be one additional support for that bridge.
Novel Technique for Online Characterization of Cartilaginous Tissue Properties
Authors: Yuan Tai-Yi , Huang Chun-Yuh , Yong Gu Wei
Published: September 2011

The goal of tissue engineering is to use substitutes to repair and restore organ function. Bioreactors are an indispensable tool for monitoring and controlling the unique environment for engineered constructs to grow. However, in order to determine the biochemical properties of engineered constructs, samples need to be destroyed. In this study, we developed a novel technique to nondestructively online-characterize the water content and fixed charge density of cartilaginous tissues. A new technique was developed to determine the tissue mechano-electrochemical properties nondestructively. Bovine knee articular cartilage and lumbar annulus fibrosus were used in this study to demonstrate that this technique could be used on different types of tissue. The results show that our newly developed method is capable of precisely predicting the water volume fraction (less than 3% disparity) and fixed charge density (less than 16.7% disparity) within cartilaginous tissues. This novel technique will help to design a new generation of bioreactors which are able to actively determine the essential properties of the engineered constructs, as well as regulate the local environment to achieve the optimal conditions for cultivating constructs.
3D Finite Element Analysis of Nutrient Distributions and Cell Viability in the Intervertebral Disc: Effects of Deformation and Degeneration
Authors: Jackson Alicia R. , Huang Chun-Yuh C. , Brown Mark D. , Yong Gu Wei
Published: September 2011

The intervertebral disc (IVD) receives important nutrients, such as glucose, from surrounding blood vessels. Poor nutritional supply is believed to play a key role in disc degeneration. Several investigators have presented finite element models of the IVD to investigate disc nutrition; however, none has predicted nutrient levels and cell viability in the disc with a realistic 3D geometry and tissue properties coupled to mechanical deformation. Understanding how degeneration and loading affect nutrition and cell viability is necessary for elucidating the mechanisms of disc degeneration and low back pain. The objective of this study was to analyze the effects of disc degeneration and static deformation on glucose distributions and cell viability in the IVD using finite element analysis. A realistic 3D finite element model of the IVD was developed based on mechano-electrochemical mixture theory. In the model, the cellular metabolic activities and viability were related to nutrient concentrations, and transport properties of nutrients were dependent on tissue deformation. The effects of disc degeneration and mechanical compression on glucose concentrations and cell density distributions in the IVD were investigated. To examine effects of disc degeneration, tissue properties were altered to reflect those of degenerated tissue, including reduced water content, fixed charge density, height, and endplate permeability. Two mechanical loading conditions were also investigated: a reference (undeformed) case and a 10% static deformation case. In general, nutrient levels decreased moving away from the nutritional supply at the disc periphery. Minimum glucose levels were at the interface between the nucleus and annulus regions of the disc. Deformation caused a 6.2% decrease in the minimum glucose concentration in the normal IVD, while degeneration resulted in an 80% decrease. Although cell density was not affected in the undeformed normal disc, there was a decrease in cell viability in the degenerated case, in which averaged cell density fell 11% compared with the normal case. This effect was further exacerbated by deformation of the degenerated IVD. Both deformation and disc degeneration altered the glucose distribution in the IVD. For the degenerated case, glucose levels fell below levels necessary for maintaining cell viability, and cell density decreased. This study provides important insight into nutrition-related mechanisms of disc degeneration. Moreover, our model may serve as a powerful tool in the development of new treatments for low back pain.
Computational Simulations for Aortic Coarctation: Representative Results From a Sampling of Patients
Authors: LaDisa John F. , Alberto Figueroa C. , Vignon-Clementel Irene E. , Jin Kim Hyun , Xiao Nan , Ellwein Laura M. , Chan Frandics P. , Feinstein Jeffrey A. , Taylor Charles A.
Published: September 2011

Treatments for coarctation of the aorta (CoA) can alleviate blood pressure (BP) gradients (Δ), but long-term morbidity still exists that can be explained by altered indices of hemodynamics and biomechanics. We introduce a technique to increase our understanding of these indices for CoA under resting and nonresting conditions, quantify their contribution to morbidity, and evaluate treatment options. Patient-specific computational fluid dynamics (CFD) models were created from imaging and BP data for one normal and four CoA patients (moderate native CoA: Δ12 mmHg, severe native CoA: Δ25 mmHg and postoperative end-to-end and end-to-side patients: Δ0 mmHg). Simulations incorporated vessel deformation, downstream vascular resistance and compliance. Indices including cyclic strain, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) were quantified. Simulations replicated resting BP and blood flow data. BP during simulated exercise for the normal patient matched reported values. Greatest exercise-induced increases in systolic BP and mean and peak ΔBP occurred for the moderate native CoA patient (SBP: 115 to 154 mmHg; mean and peak ΔBP: 31 and 73 mmHg). Cyclic strain was elevated proximal to the coarctation for native CoA patients, but reduced throughout the aorta after treatment. A greater percentage of vessels was exposed to subnormal TAWSS or elevated OSI for CoA patients. Local patterns of these indices reported to correlate with atherosclerosis in normal patients were accentuated by CoA. These results apply CFD to a range of CoA patients for the first time and provide the foundation for future progress in this area.
Trend Towards Integrated Facilities: Marseille
Authors: Garci´a de Herreros David
Published: September 2011

In May 2005, the Spanish based group URBASER was awarded by the “Metropolitan Provence of Marseille” with the Design, Financing, Construction and Operation for a 20 year period of an Integrated Waste Treatment Facility in the southern French city of Marseille. The Integrated Facility will treat 390,000 tons per year of mainly unsorted Municipal Solid Waste generated by 1 million inhabitants in the 18 towns of the Region.
The Latest Updates on Waste-to-Energy and Conversion Technologies: Plus Projects Under Development
Authors: Gershman Harvey W.
Published: September 2011

Technologies that burn municipal solid waste (MSW) with energy recovery have come a long way in the past 100 years. Although the last new MSW-processing waste-to-energy (WTE) facilities constructed in the United States commenced operations in 1996, recent years have witnessed a renaissance of interest and activity, some of it in traditional mass-burn combustion but more in new conversion technologies. This presentation will provide an update on these renewable energy technologies and highlight several projects under development.
SCR DeNOx Systems in Hitachi Zosen Inova’s European EfW Facilities
Authors: Chromec Peter
Published: September 2011

Nitrogen Oxide (NOx) emissions of new Energy-from-Waste (EfW) facilities, especially in ozone non-attainment zones, are coming under increased scrutiny by permitting agencies in the US as new EfW projects are permitted. While the EPA national technology based limits for EfW plants under the New Source Performance Standards are still at 150 ppmdv at 7% O2, many permitting authorities are requiring substantially lower limits for new EfW plants in their states or air quality regions under EPA’s New Source Review/Prevention of Significant Deterioration air quality permitting program. This trend is directly related to the question, how the Lowest Achievable Emission Rate (LAER) and Best Available Control Technology (BACT) limits for NOx in EfW plants should be defined in ozone nonattainment and attainment areas respectively. Since lower NOx limits increase the cost of EfW as a sustainable waste management method, too stringent emission limits may have the adverse effect that more waste is landfilled due to the economic competition between these waste management methods which will actually lead to higher overall emissions and lower sustainability. Like other technology suppliers, Hitachi Zosen Inova (HZI, earlier AE&E Inova), a worldwide leader in EfW technology, has used various NOx control options. Apart from standard SNCR systems which can safely meet the EPA NSPS limits, there is DyNOR™, the advanced SNCR-based technology which can safely reach values below 100 ppmdv at 7% O2, and the SCR (Selective Catalytic Reduction) technology, which can reach values down to far below 50 ppmdv at 7% O2. However, once a certain emission limit is determined, the question is how this limit can be safely and continuously achieved with the lowest possible cost per ton of waste treated.
Advanced Boiler Cleaning Solutions for Increased Boiler Runtime
Authors: Billings Brandon , Rodia Greg , Scavone Ryan , Tirkschleit Marc
Published: September 2011

Clyde Bergemann Power Group (CBPG) and Covanta Niagara, a Waste-to-Energy facility (WTE) plagued by boiler cleanliness issues, have collectively worked to implement a Shower Clean System (SCS) trial in Boiler 3’s second pass. The SCS’s cleaning concept is designed to traverse down through the roof of the boiler into a narrow open pass using a custom design water spray nozzle to clean the water walls. A SCS trial assembly was operated at the facility from July 27, 2010 to September 1, 2010. A total of 16 cleaning cycles were performed. During this trial period, on average, the second pass outlet flue gas temperature saw a 62 degrees Fahrenheit (degF) reduction after a cleaning event was performed. Based on years of SCS operating experience, CBPG determined a cleaning event should not be initiated if the temperature rise in the second pass is less than 30 degF. This insures that the second pass would not be over cleaned causing material stress to the water walls. In order to estimate the proper cleaning frequency for Niagara’s permanent SCS, an average second pass fouling rate was calculated. Using the fouling rate and the minimum allowable flue gas temperature rise, a cleaning frequency was estimated. Based on the trial results, the recommended operating frequency of the permanent SCS at Covanta Niagara will employ the Umbrella nozzle in the second pass twice per day or once per shift (12 hours). This recommendation is based on observations of the six week operating trial of the SCS and is subject to change based on myriad variables such as waste characteristics and first pass outlet flue gas temperatures. Typical boiler operation at Niagara utilizes industrial cleanings once per week to extend its boiler runtime. During the six week trial the SCS helped reduce the total number of industrial cleanings necessitated to keep the boiler online. Once a permanent SCS is implemented and used daily, there could be significant benefits to boiler runtime without having a total dependence on industrial cleanings. Becoming more reliant on the SCS to maintain lower boiler flue gas temperatures will result in less costs associated with online boiler cleaning and potentially less damage to the third pass convective surface from less high pressure water washing.
Changes in Public Perception of Role of Waste-to-Energy for Sustainable Waste Management of MSW
Authors: Themelis Nickolas J.
Published: September 2011

In the last ten years, public and government perceptions of waste-to-energy have changed considerably. Most people who bothered to visit waste management facilities recognize that landfilling can only be replaced by a combination of recycling and thermal treatment with energy recovery. During the same period, the Earth Engineering Center (EEC) of Columbia University research and public information programs have concentrated on advancing all means of sustainable waste management in the U.S. and abroad. The results of EEC research are exemplified in the graphs of the Hierarchy of Waste Management and the Ladder of Sustainable Waste Management of nations; in this paper, the latter has also been used to compare the waste management status of the fifty states of the Union. This paper also describes how the European Union has directed that thermally efficient treatment of MSW is equivalent to recycling. The rapid growth of WTE in this century is exemplified by the hundreds of new WTE plants that have been built or are under construction, most with, government assistance as in the case of other essential infrastucture. The need for concerted action by concerned scientists and engineers around the world has led to the formation of the Global WTERT Council. By now there are sister organizations of EEC and WTERT in Brazil, Canada, China, France, Germany, Greece (SYNERGIA) and Japan. Others are being formed in other countries.
Induction Heat Tube Extraction for Generating Bank Replacement
Authors: Blaser Wade P.
Published: September 2011

Induction is used to rapidly heat generating bank tubes in situ to 1000 C, which causes plastic deformation due to thermal expansion under restraint by the tube sheet (drum). When cooled, the tube shrinks, breaking contact with the drum, providing for ease of removal. A second process has also been developed, and Patented, for the removal of previously over expanded tube stubs from headers and drums. The Heat and PullSM method extracts the stub by hydraulic jacking from outside the drum while Induction heating from inside the drum. Prior bell removal is not required, as the bell collapses and is pulled through with the stub. Cost and schedule improvements may be achieved with both Induction Heat Tube Extraction processes. Both processes eliminate the risk of tube seat damage often caused by the traditional tube removal methods of arc air gouging or flame cutting. This paper describes the technology of both Induction Heat Tube Extraction methods as well as developments on current boiler generating bank replacement jobs.
Numerical Modeling of Pollution Formation in Waste-to-Energy Systems Using Computational Fluid Dynamics
Authors: Frank Alex , Castaldi Marco J. , Nakamura Masato R.
Published: September 2011

This investigation has been undertaken to better understand pollutant formation in Waste-to-Energy (WTE) systems by using Computation Fluid Dynamics (CFD). An above-grate gas phase only model was built and calculated in FLUENT™ with the intent of specifically studying the factors that influence the formation of NOx. Results are shown for a typical reciprocating-grate WTE boiler operating on municipal solid waste (MSW). Contours of velocity, temperature, CO2, CO, H2O, and O2 agree well with previous modeling and data resulting in a high fidelity model that can be implemented in the next phase of this research. Preliminary data is shown for thermal NOx and the results are promising. The next phase of this research will include the development and implementation of detailed kinetic mechanisms (DKM) to model NOx formation with the current boiler presented as well as others with varying fuels.
Behind the Scenes: Sneak Peak at Procurement of Innovative Recycling and Waste-to-Fuel Conversion System Expected to Yield 80% Diversion
Authors: Brickner Robert H.
Published: September 2011

New Hanover County, NC, hired Gershman, Brickner & Bratton, Inc. (GBB) to help prepare a Request for Proposals (RFP) for the management and long-term operations of the County’s solid waste disposal facilities, which include a secure landfill with more than 40 years of remaining life, a 20+ year old waste-to-energy (WTE) plant, and seven recycling drop-off sites receiving over 200,000 tons per year. The RFP requested a single-service provider to provide all of the services currently being undertaken by the County under a single contract going forward. During the course of the procurement, GBB’s Project Manager made three presentations to the New Hanover County Board of Commissioners (County Board), advancing the RFP process from eight vendor proposals, to interviews of five firms and performing a technical and economic review of each, to short-listing two firms, to the final recommendation of going forward with high-tech start-up R3 Environmental LLC (R3). In September 2010, the County Board signed a landmark contract with R3 for the management of the County’s waste system that was intended to position the County as a world leader in innovative disposal, according to County officials. Under the agreement, R3 was to implement a modern Municipal Solid Waste (MSW) processing facility pulling out recyclables and making a low-ash, high-BTU Refused-Derived Fuel (RDF) biomass product, refurbishing the current mass-burn WTE facility into an RDF biomass-fired system, and implementing a new construction waste and demolition debris recycling (C&D) processing system. The new solid waste sorting facility, with advanced machinery, dubbed a “Smart MRF,” was expected to be in operation in two years, extracting recyclables and converting the organic waste stream into fuel. R3 guaranteed to divert over 80% of the incoming solid waste from the landfill. This paper provides a unique behind-the-scenes look at the procurement process used to select this “innovative technology proposal” from R3 as it pertained to recycling potential, carbon credits and renewable energy credits, and significant long-term cost benefits to the County. It will also provide a review of the vendor evaluation process that led to this landmark contract, from the RFP preparation, proposals evaluation, technical/economic reviews, short-listing, recommendations, and technical contract negotiation.
Energetic and Environmental Analysis of a New Cogenerative Configuration for the Waste to Energy Plant of Piacenza
Authors: De Servi Carlo , Rigamonti Lucia , Consonni Stefano
Published: September 2011

This study aims at estimating the energy and environmental performances of a new cogenerative configuration of the waste to energy (WTE) plant in Piacenza. At present, the plant is authorized to treat 120,000 t/y of waste, but this limit does not represent the full treatment capacity of the facility. To exploit the plant potential and, at the same time, to reduce total equivalent emissions of the WTE process, a cogenerative configuration has been proposed. In this new scenario a back pressure turbine would be installed in parallel to the existing one, in order to supply heat to the district heating network of Piacenza and the total amount of waste treated per year by the facility would be increased to 134,100 t. The increase of 14,100 t should be satisfied by industrial and commercial waste, which would otherwise go to landfill. To compare the cogenerative scenario with the current situation, the environmental impact for the two cases has been evaluated by means of a life cycle assessment methodology. The results of the analysis show that the new configuration can ensure significant energy and environmental benefits.
A Directed Protein Interaction Network for Investigating Intracellular Signal Transduction
Authors: Vinayagam Arunachalam , Stelzl Ulrich , Foulle Raphaele , Plassmann Stephanie , Zenkner Martina , Timm Jan , Assmus Heike E. , Andrade-Navarro Miguel A. , Wanker Erich E.
Published: September 2011

Effective prediction of the direction of signal flow in an interaction network enables modeling of signaling dynamics and identification of regulatory proteins.
Small Molecule–Mediated Activation of the Integrin CD11b/CD18 Reduces Inflammatory Disease
Authors: Maiguel Dony , Faridi Mohd Hafeez , Wei Changli , Kuwano Yoshihiro , Balla Keir M. , Hernandez Dayami , Barth Constantinos J. , Lugo Geanncarlo , Donnelly Mary , Nayer Ali , Moita Luis F. , Schürer Stephan , Traver David , Ruiz Phillip , Vazquez-Padron Roberto I. , Ley Klaus , Reiser Jochen , Gupta Vineet
Published: September 2011

Drugs that activate integrins inhibit leukocyte recruitment to sites of inflammation.
Crowdsourcing Network Inference: The DREAM Predictive Signaling Network Challenge
Meeting Information:
The DREAM4 Predictive Signaling Network Challenge took place in the summer of 2009. Results were presented at the DREAM4 conference, December 2009, The Broad Institute of MIT and Harvard, Cambridge, Massachusetts.
Authors: Prill Robert J. , Saez-Rodriguez Julio , Alexopoulos Leonidas G. , Sorger Peter K. , Stolovitzky Gustavo
Published: September 2011

By aggregating the efforts of the research community, comprehensive and accurate inference of signaling networks may become achievable.
Variable Entrainment
Authors: Ray L. Bryan
Published: September 2011

A positive feedback loop in a biological oscillator allows effective setting of the clock by external cues.
COMPLEXITY AND SYNCHRONIZATION IN CHAOTIC INJECTION-LOCKING SEMICONDUCTOR LASERS
Authors: YANG LEI , PAN WEI , YAN LIAN SHAN , LUO BIN , XIANG SHUI YING , JIANG NING
Published: September 2011

The chaotic complexity properties of semiconductor lasers in the chaotic synchronization systems are investigated numerically, based on the information theory based quantifier, the permutation entropy (PE). We find that, on the one hand, the degree of complexity for the master laser increases with the feedback strength firstly and then saturate at higher feedback strength, but are hardly affected by the feedback delay. On the other hand, for the slave laser, the complexity degree is closer to that for the master laser when the high quality chaos synchronization is obtained, which shows that, the PE method is a successful quantifier to evaluate the degree of complexity for the chaotic signals in chaos synchronization systems, and can be considered as a complementary tool to observe the synchronization quality.
THE TOPOLOGICAL STRUCTURE OF SINGLE VORTEX IN THE FF STATE
Authors: SHANG XINLE , ZHANG PENGMING , ZUO WEI
Published: September 2011

In this paper, we study the coexistence of the vortex and the FF state by using the generalized Ginzburg–Landau (GL) functional with the applied magnetic field, and obtain the numeric solutions. Furthermore, we investigate the topological structure of the vortex and find that the property of vortices relies heavily on the modulation q along z-axis. There is no topological vortex when q < qp, and the value [Formula: see text] is more favorable for the topological vortex. Moreover the magnetic field at the core of the vortex is obtained for the topological vortex.
INSTABILITY OF QCD GHOST DARK ENERGY MODEL
Authors: EBRAHIMI ESMAEIL , SHEYKHI AHMAD
Published: September 2011

We investigate the instability of the ghost dark energy model against perturbations in different cases. To this goal we use the squared sound speed [Formula: see text] whose sign determines the stability of the model. When [Formula: see text] the model is unstable against perturbation. At first we discuss the noninteracting ghost dark energy model in a flat FRW universe and find out that such a model is unstable due to the negativity of the [Formula: see text] in all epoches. The interacting ghost dark energy model in both flat and nonflat universe are studied in the next parts and in both cases we find that the squared sound speed of ghost dark energy is always negative. This implies that the perfect fluid for ghost dark energy is classically unstable against perturbations. In both flat and non flat cases we find that the instability of the model increases with increasing the value of the interacting coupling parameter.
INFLUENCE OF ADHESION LAYERS ON THE SURFACE MORPHOLOGY OF PLATINUM-BASED BOTTOM ELECTRODES FOR Pb(Zr,Ti)O3 THIN FILMS
Authors: HUY NGUYEN THANH , HUNG VU NGOC
Published: September 2011

A thin adhesion layer is required to glue Pt bottom electrodes of ferroelectric Pb(Zr,Ti)O 3 thin films to a SiO 2/ Si wafer. Here we report the effect of adhesion layers, Ti and TiO 2, on the crystalline structure and surface properties of Pt electrode. The results show that the hillock formation is observed for the case of Ti glue layer, while the surface of Pt layer is flat and uniform with TiO 2 layer used instead. The crystallization in PZT thin films on Pt / TiO 2/ SiO 2/ Si substrate is investigated during post-deposition annealing. The perovskite phase is completely formed in the film annealed at 650°C for one hour.
STRUCTURAL PROPERTIES OF AlN FILMS WITH OXYGEN CONTENT DEPOSITED BY REACTIVE MAGNETRON SPUTTERING: XRD AND XPS CHARACTERIZATION
Authors: GARCÍA-MÉNDEZ MANUEL , MORALES-RODRÍGUEZ SANTOS , SHAJI SADASIVAN , KRISHNAN BINDU , BARTOLO-PÉREZ PASCUAL
Published: September 2011

A set of aluminium nitride ( AlN ) and oxidized AlN ( AlNO ) thin films were grown with the technique of direct current (dc) reactive magnetron sputtering. The main purpose of this investigation is to explore the influence of the oxygen on the structural properties of AlN and AlNO films. The crystalline properties and chemical identification of phases were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Electrical properties were analyzed from I-V measurements. It was found that films crystallized under the AlN würzite structure and presented a polycrystalline preferential growth along [0001] direction, perpendicular to substrate. Small amounts of secondary aluminium oxide phases were detected too. The oxide phases can induce defects, which can alter crystallinity of films.
LONG-TERM INFLUENCE OF CONCRETE DEGRADATION ON DAM–FOUNDATION INTERACTION
Authors: BURMAN A. , MAITY D. , SREEDEEP S. , GOGOI I.
Published: September 2011

The dam–foundation interaction behavior under the application of seismic load has been investigated in the present paper using finite element technique in the time domain. Since the dam face is in constant contact with water, concrete degradation due to hygromechanical loading is inevitable and should be considered in the analysis procedure. This ageing process of concrete leads to loss of stiffness and strength of the material. Therefore, to assess the behavior of the dam at a later stage of its life, it is important to determine the proper strength of the concrete at a certain age. An approach to include the time-dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic degradation index is presented. An iterative scheme has been developed to model the dam–foundation interaction effects of the coupled system. The strains and the displacements are observed to increase if the ageing procedure of the gravity dam is taken into account. The long-term behavior of the aged concrete gravity and foundation interaction has been observed by using a developed ageing model for concrete.
DYNAMIC ELASTOPLASTIC ANALYSIS USING THE MESHLESS LOCAL NATURAL NEIGHBOR INTERPOLATION METHOD
Authors: CHEN SHENSHEN , LI QINGHUA , LIU YINGHUA , XIA JIANGTAO , XUE ZHIQING
Published: September 2011

Dynamic elastoplastic analysis is a subject of great engineering importance and can practically be handled only by numerical methods due to its complexity. The aim of this paper is to develop the meshless local natural neighbor interpolation (MLNNI) method to perform the dynamic analysis of elastoplastic structures under plane stress or plane strain conditions. The MLNNI, as an effective truly meshless method for solving partial differential equations, employs local weak forms over a local subdomain and shape functions from the natural neighbor interpolation (NNI). The shape functions so formulated possess delta function property and, therefore, the essential boundary conditions can be implemented as ease as in the finite element method (FEM). The predictor-corrector form of the Newmark algorithm is used for the time-marching process and iterations are performed at every time step. The applied loads can have any transient time variation. Comparative results are presented at the end to illustrate the effectiveness of the proposed method and demonstrate its accuracy.
DISPERSION ANALYSIS OF AN ENERGY-ORTHOGONAL THIN PLATE FINITE ELEMENT
Authors: CASTRO FRANCISCO JOSÉ BRITO
Published: September 2011

This paper studies the propagation of plane harmonic waves in thin plates discretized by using a finite element where the stiffness matrix and the elastic energy are split into basic and higher-order components. These ones are obtained from constant and deviatoric curvature fields, respectively. Based on the properties of the higher-order energy, four reference frequencies are defined. Depending on the desired precision, one of those values is selected as optimum cutoff frequency to properly capture a wave field. A scaling coefficient multiplying the higher-order stiffness is updated in order to enhance the accuracy of the discretized model.
THE INVERSE PROBLEM OF RED BLOOD CELLS DEFORMED BY OPTICAL TWEEZERS
Authors: ZHOU X. Z. , ZHAO F. P. , SUN Z. H. , WU H. A.
Published: September 2011

Optical tweezers are widely used to study the mechanical properties of human red blood cells. This paper examines the inverse problem of computing constitutive parameters from the experimental loading-response data. Hyperelastic constitutive models are employed to characterize the stress–strain relationship of red blood cells. The large deformation and evolution of stress in red blood cells under different tensile loadings are investigated using finite element simulations. The results show that the Yeoh model provides a better characterization of human red blood cells. A nonlinear regression analysis method is presented to derive hyperelastic parameters from the experimental results. The obtained constitutive model and parameters are validated by comparing the force–displacement curves from finite element simulations and from experimental data.
NONCONVENTIONAL FINITE ELEMENT MODELS FOR NONLINEAR ANALYSIS OF BEAMS
Authors: KIM WOORAM , REDDY J. N.
Published: September 2011

In this study, mixed finite element models of beam bending are developed to include the membrane forces and shear forces in addition to the bending moments and displacements. Mixed finite element models were developed based on the weighted residual statements of governing equations. The Euler–Bernoulli beam theory (EBT) and the Timoshenko beam theory (TBT) are used. The effectiveness of the new mixed models is evaluated in light of other mixed models to show the advantages. Each newly developed model is examined and compared with other models to verify its performance under various boundary conditions. In the linear analysis, solutions are compared with available analytical solutions and solutions of existing models. In the nonlinear case, direct and Newton–Raphson methods are used to solve the nonlinear equations. The converged solutions are compared with available solutions of the displacement models. Post-processed data of the mixed model developed herein shows better accuracy than the conventional displacement-based model.
SYSTEMATIC MODELING AND MODEL-BASED SIMULATION OF A REMOTELY OPERATED VEHICLE USING MATLAB AND SIMULINK
Authors: CHIN C. S.
Published: September 2011

Dynamic modeling and simulation of underwater robotic vehicles is essential for control. In this paper, systematic dynamic modeling and simulation of a remotely operated vehicle (ROV) is developed and named as ROV Design and Analyses (RDA). For the initial design, hydrodynamic coefficients used in the ROV dynamic model were estimated using computational fluid dynamic software and experiments. The proposed RDA toolbox written in MATLAB™ and Simulink™ platform provides a means to simulate the mathematical models of ROV and the control system design before final hardware implementation. The control simulation using a proportional–integral–derivative controller is able to model the positions and velocities output of the ROV that is highly uncertain and nonlinear.
DGHPSIM:
Authors: Günal Murat M. , Pidd Michael
Published: September 2011

The British National Health Service (NHS) has a performance management framework that aims to guarantee short waiting times for patients by including mandatory targets for hospitals. DGHPSim is a suite of four components that simulates the activities of an NHS general hospital to show the effect of different policies on waiting times in these hospitals. DGHPSim has a generic structure that is used to simulate a particular hospital by employing data appropriate to that hospital from available data sets. Two of the components of DGHPSim, the accident and emergency simulator and the outpatient simulator, may be used independently as stand-alone simulators of these hospital functions. The DGHPSim suite incorporates a novel way of simulating the multitasking behavior of clinicians and uses transition matrices, extracted from standard datasets, to represent the states through which patients pass and the wards in which they may be treated. As a whole, the DGHPSim suite may be used to investigate improvement options before their implementation or to investigate how a hospital has improved its performance. We show how DGHPSim is used to investigate reported performance improvements in an English general hospital.
Prefetch-aware shared resource management for multi-core systems
Authors: Ebrahimi Eiman , Lee Chang Joo , Mutlu Onur , Patt Yale N.
Published: September 2011

Chip multiprocessors (CMPs) share a large portion of the memory subsystem among multiple cores. Recent proposals have addressed high-performance and fair management of these shared resources; however, none of them take into account prefetch requests. Without prefetching, significant performance is lost, which is why existing systems prefetch. By not taking into account prefetch requests, recent shared-resource management proposals often significantly degrade both performance and fairness, rather than improve them in the presence of prefetching.

This paper is the first to propose mechanisms that both manage the shared resources of a multi-core chip to obtain high-performance and fairness, and also exploit prefetching. We apply our proposed mechanisms to two resource-based management techniques for memory scheduling and one source-throttling-based management technique for the entire shared memory system. We show that our mechanisms improve the performance of a 4-core system that uses network fair queuing, parallelism-aware batch scheduling, and fairness via source throttling by 11.0%, 10.9%, and 11.3% respectively, while also significantly improving fairness.
Energy-efficient mechanisms for managing thread context in throughput processors
Authors: Gebhart Mark , Johnson Daniel R. , Tarjan David , Keckler Stephen W. , Dally William J. , Lindholm Erik , Skadron Kevin
Published: September 2011

Modern graphics processing units (GPUs) use a large number of hardware threads to hide both function unit and memory access latency. Extreme multithreading requires a complicated thread scheduler as well as a large register file, which is expensive to access both in terms of energy and latency. We present two complementary techniques for reducing energy on massively-threaded processors such as GPUs. First, we examine register file caching to replace accesses to the large main register file with accesses to a smaller structure containing the immediate register working set of active threads. Second, we investigate a two-level thread scheduler that maintains a small set of active threads to hide ALU and local memory access latency and a larger set of pending threads to hide main memory latency. Combined with register file caching, a two-level thread scheduler provides a further reduction in energy by limiting the allocation of temporary register cache resources to only the currently active subset of threads. We show that on average, across a variety of real world graphics and compute workloads, a 6-entry per-thread register file cache reduces the number of reads and writes to the main register file by 50% and 59% respectively. We further show that the active thread count can be reduced by a factor of 4 with minimal impact on performance, resulting in a 36% reduction of register file energy.
Adaptive granularity memory systems
Authors: Yoon Doe Hyun , Jeong Min Kyu , Erez Mattan
Published: September 2011

We propose
adaptive granularity
to combine the best of fine-grained and coarse-grained memory accesses. We augment virtual memory to allow each page to specify its preferred granularity of access based on spatial locality and error-tolerance tradeoffs. We use sector caches and sub-ranked memory systems to implement adaptive granularity. We also show how to incorporate adaptive granularity into memory access scheduling. We evaluate our architecture with and without ECC using memory intensive benchmarks from the SPEC, Olden, PARSEC, SPLASH2, and HPCS benchmark suites and micro-benchmarks. The evaluation shows that performance is improved by 61% without ECC and 44% with ECC in memory-intensive applications, while the reduction in memory power consumption (29% without ECC and 14% with ECC) and traffic (78% without ECC and 66% with ECC) is significant.
SpecTLB
Authors: Barr Thomas W. , Cox Alan L. , Rixner Scott
Published: September 2011

Data-intensive computing applications are using more and more memory and are placing an increasing load on the virtual memory system. While the use of large pages can help alleviate the overhead of address translation, they limit the control the operating system has over memory allocation and protection. We present a novel device, the SpecTLB, that exploits the predictable behavior of reservation-based physical memory allocators to interpolate address translations.

Our device provides speculative translations for many TLB misses on small pages without referencing the page table. While these interpolations must be confirmed, doing so can be done in parallel with speculative execution. This effectively hides the execution latency of these TLB misses. In simulation, the SpecTLB is able to overlap an average of 57% of page table walks with successful speculative execution over a wide variety of applications. We also show that the SpecTLB outperforms a state-of-the-art TLB prefetching scheme for virtually all tested applications with significant TLB miss rates. Moreover, we show that the SpecTLB is efficient since mispredictions are extremely rare, occurring in less than 1% of TLB misses. In essense, the SpecTLB effectively enables the use of small pages to achieve fine-grained allocation and protection, while avoiding the associated latency penalties of small pages.
Scalable power control for many-core architectures running multi-threaded applications
Authors: Ma Kai , Li Xue , Chen Ming , Wang Xiaorui
Published: September 2011

Optimizing the performance of a multi-core microprocessor within a power budget has recently received a lot of attention. However, most existing solutions are centralized and cannot scale well with the rapidly increasing level of core integration. While a few recent studies propose power control algorithms for many-core architectures, those solutions assume that the workload of every core is independent and therefore cannot effectively allocate power based on thread criticality to accelerate multi-threaded parallel applications, which are expected to be the primary workloads of many-core architectures. This paper presents a scalable power control solution for many-core microprocessors that is specifically designed to handle realistic workloads, i.e., a mixed group of single-threaded and multi-threaded applications. Our solution features a three-layer design. First, we adopt control theory to precisely control the power of the entire chip to its chip-level budget by adjusting the aggregated frequency of all the cores on the chip. Second, we dynamically group cores running the same applications and then partition the chip-level aggregated frequency quota among different groups for optimized overall microprocessor performance. Finally, we partition the group-level frequency quota among the cores in each group based on the measured thread criticality for shorter application completion time. As a result, our solution can optimize the microprocessor performance while precisely limiting the chip-level power consumption below the desired budget. Empirical results on a 12-core hardware testbed show that our control solution can provide precise power control, as well as 17% and 11% better application performance than two state-of-the-art solutions, on average, for mixed PARSEC and SPEC benchmarks. Furthermore, our extensive simulation results for 32, 64, and 128 cores, as well as overhead analysis for up to 4,096 cores, demonstrate that our solution is highly scalable to many-core architectures.
Acute Liver Injury with Severe Coagulopathy in Marasmus Caused by a Somatic Delusional Disorder
Authors: Stein Lance L. , Jesudian Arun B.
Published: September 2011

Marasmus is a severe form of protein-calorie malnutrition characterized by the depletion of fat stores, muscle wasting, and the lack of edema. In developed countries, marasmus is often the result of anorexia nervosa. Abnormal transaminases with liver synthetic dysfunction have rarely been reported with anorexia nervosa. To our knowledge, we report the first detailed case of acute liver injury with severe coagulopathy (INR>1.5) in a patient with marasmus due to self-induced calorie restriction caused by a somatic delusional disorder. This case highlights the severity of liver injury that may occur with significant weight loss from self-induced calorie restriction and the rapid normalization of this injury with treatment. It is important for clinicians to be aware of patterns of acute liver injury in patients with severe protein-calorie malnutrition, regardless of the underlying cause.
Laparoscopic Bipolar Coagulation of Hypogastric Artery in Postpartum Haemorrhage: A Case Report
Authors: Panuccio Enrico , Volpi Eugenio , Ferrero Annamaria , Sismondi Piero
Published: September 2011

Background. Postpartum haemorrhage (PPH) is a significant contributor to worldwide maternal morbidity and mortality. When PPH continues despite aggressive medical treatment, early consideration should be given to surgical intervention. Various surgical interventions may be used but conservative interventions are recommended primarily.Case. This case report describes laparoscopic coagulation of hypogastric artery technique in a patient with PPH.Conclusions. Laparoscopic ligature of the hypogastric artery for PPH treatment can be a valid alternative to laparotomy in patients with vaginal delivery.
Combinatorics inN=1Heterotic Vacua
Authors: Lee Seung-Joo
Published: September 2011

We briefly review an algorithmic strategy to explore the landscape of heteroticE8×E8vacua, in the context of compactifying smooth Calabi-Yau threefolds with vector bundles. The Calabi-Yau threefolds are algebraically realised as hypersurfaces in toric varieties, and a large class of vector bundles are constructed thereon as monads. In the spirit of searching for standard-like heterotic vacua, emphasis is placed on the integer combinatorics of the model-building programme.