bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Symphony Hall: L'Auditori Barcelona
Authors: Arau-Puchades Higini 
Published: February 2013

This paper describes the design of the Concert Hall of Barcelona, called “L'Auditori”. The acoustical design of the project was finished in 1990 but it was built later and finally opened on 22nd March 1999. The acoustics of the concert hall have been very well received by audiences. In this manuscript, we outline several acoustic features which had to be designed using old methods because the more modern systems had not yet been developed. However, construction was delayed nine years, which meant that new computer tools were available when work was coming to an end in 1990, it allowed us to carry out an overall review of many aspects of the design, A very important issue that required years of research before we discovered the cause of the problem was that musicians could not hear themselves on stage, yet Gade's measurements of ST1 made in 2001 were comparable with those found in the best reference halls. In this paper we discuss this issue, and conclude that the musicians were correct.
New methods for the localization of discontinuities of the first kind for functions of bounded variation
Authors: Ageev Alexandr L. , Antonova Tatyana V. 
Published: February 2013

Abstract.
We construct and study methods for approximating the positions (localization) of discontinuities of the first kind of a one-dimensional function.
Instead of the exact function, its approximation in and the perturbation level are known; smoothness conditions are imposed on the function outside
the discontinuities.
The number of discontinuities is countable, and all the discontinuities are divided into two sets: with the absolute value of the jump greater than some
positive and discontinuities satisfying a smallness condition for the value of the jump. It is required to find the number of discontinuities in the first
set and localize them using the approximately given function and the perturbation level. Since the problem is ill-posed, regularization algorithms should be used for its solution.
Under additional conditions on the exact function, we construct regular methods for the localization
of discontinuities and obtain estimates for the accuracy of localization and for the separability threshold, which is another important characteristic of the method.
The order optimality of the constructed methods on classes of functions with discontinuities is established.
An inverse problem for the quadratic pencil of non-self-adjoint matrix operators on the half-line
Authors: Bondarenko Natalia , Freiling Gerhard 
Published: February 2013

Abstract
We consider a pencil of non-self-adjoint matrix Sturm–Liouville
operators on the half line and study the inverse problem of constructing this pencil
by its Weyl matrix. A uniqueness theorem is proved, and a constructive algorithm for the solution
is obtained.
Variational smoothness assumptions in convergence rate theory—an overview
Authors: Flemming Jens 
Published: February 2013

Abstract.
Variational smoothness assumptions are a concept for measuring abstract
smoothness of solutions to operator equations. Such assumptions are useful
for analyzing regularization methods, especially for proving convergence
rates in Banach spaces and in more general settings. We collect results from different papers published by several
authors during the last five years. The aim is to present an overview of
this relatively new concept to the interested reader without going too
deep into the details.
A Laboratory Study to Predict the Rutting and Fatigue Behavior of Asphalt Concrete Using the Indirect Tensile Test
Authors: Wen Haifang , Bhusal Sushanta 
Published: February 2013

Abstract
Rutting, fatigue, moisture susceptibility, and thermal cracking are the primary distresses of asphalt pavement. Currently several test methods are used to predict the rutting and fatigue behavior of asphalt concrete. This study uses the indirect tensile (IDT) test to evaluate both the rutting and fatigue behavior of asphalt. Recycled concrete aggregate (RCA) and virgin aggregate are blended at different percentages (0 %, 20 %, 40 %, 60 %, 80 %, and 100 %) to produce mixes with a variety of fatigue and rutting performance. The IDT rutting test was performed by running high temperature IDT flow time and strength tests. In addition, flow number tests were performed using an asphalt mixture performance tester (AMPT). A strong correlation is observed between the high temperature IDT flow time/strength and flow number from AMPT. The test results show that IDT tests can be used to predict the rutting behavior of asphalt concrete at high temperatures. To characterize fatigue, cyclic IDT and monotonic fracture energy tests were performed at intermediate temperatures. At intermediate temperatures, good correlation is found between the fatigue life obtained from cyclic IDT test results and the fracture energy obtained from monotonic fracture test results. Based on the laboratory test results, the IDT test can be used to evaluate both the fatigue and rutting behavior of asphalt concrete. Considering that IDT testing has been used to characterize thermal cracking and moisture susceptibility, the IDT test has the potential to serve as a single performance test for fatigue, rutting, thermal cracking and moisture damage. Validation of the findings with more materials and field performance are recommended.
Stress-Relaxation Cracking Test for Welded Joints
Authors: Kuhn B. , Ullrich C. , Tschaffon H. , Beck T. , Singheiser L. 
Published: February 2013

Abstract
Scientific and technological research concerning the underlying damage mechanism and the evaluation of adequate countermeasures of so called strain-age (SAC), stress-relaxation (SRC), or ductility-dip cracking (DDC) of service exposed base materials and welded joints suffers a lack of specialized testing methods, that are able to detect the most cracking susceptible area of the weld and result in a definite “pass or fail” distinction for every single experiment without leaving ambiguity in the interpretation of testing results. For these reasons an advanced four-point-bending technique was developed on the basis of the three-point-bending test established by van Wortel. The proposed method was applied for evaluating the cracking susceptibility of Alloy617B welded joints. The technique proved to be suitable for the base metal as well as for welded joints. All as-welded joints failed by interdentritic fracture within the weld and the site of fracture corresponded well with the maximum hardness location (HV10) evaluated after the bending tests. The proposed testing method distinctively provided evidence for reduced cracking susceptibility of welded joints caused by a post-weld heat treatment (980°C, 3 h, air). All heat treated joints surpassed the bending test without cracking underlining the unambiguity of the proposed testing technique.
Advances in the Understanding of Gelation in the Framework of the Test ASTM D5133
Authors: Maroto-Centeno J. A. , Pérez-Gutiérrez T. , Quesada-Pérez M. 
Published: February 2013

Abstract
This work presents a theoretical survey that sheds light on the physical meaning of the gelation index, that is, the main parameter involved in ASTM D5133. More specifically, it is proved that the pulse-shaped region of the gelation curve can be explained as the relief of the supersaturation of the solution, which is a nucleation process that finishes when the saturation ratio takes a value equal to 1. Comparison between experiments and the theoretical approach put forward in this work reveals qualitative agreement. This work also confirms the poor reproducibility of ASTM D4684, which is an alternative test for the evaluation of gelation in engine oils. Particularly, it is shown that the poor reproducibility of this test can be attributed to a systematic error made during the measurements. The lack of accuracy of the temperature, in particular the final test temperature, could be the main cause for discrepancies between laboratories. Finally, it is shown that in order to predict gelation within ASTM D5133, not only must the gelation index be considered, but the gelation index temperature also plays an important role.
Improved Digital Image Correlation Method for Eliminating Pixel Shape-Induced Errors in Shear-Strain Calculations
Authors: Peng Bei , Huang Chengcheng , Zhou Wu , Yu Huijun , Zeng Zhi 
Published: February 2013

Abstract
Digital image correlation is widely used in non-contact displacement/strain measurements for numerous engineering applications. Under rigid body rotation or shear deformation, however, the calculated surface strain of specimens is unreliable when camera pixels are characterized by non-square geometry, that is, the width-to-height ratio of pixels is not 1. This study analyzes the computational errors introduced by cameras, and proposes a modified least-squares method that eliminates such errors when the strain field is calculated. Experimental results confirm that the algorithm validly and effectively computes shear strain.
Computation and Uncertainty Evaluation of Offset Yield Strength
Authors: Matusevich Ariel E. , Massa Julio C. , Mancini Reinaldo A. 
Published: February 2013

Abstract
This paper presents computer procedures for the calculation of offset yield strength (Sy) and for the evaluation of the uncertainty in its computation. Offset yield strength is obtained from the plot of stress-strain data recorded in a tension test, as the stress that corresponds to the intersection between the stress-strain curve and a line parallel to its proportional region (offset by a prescribed strain). In the proposed method, the problem is reduced to finding the point of intersection between two straight lines, one that fits the curve in the neighborhood of the intersection and the offset line. For the fitting of each line, we propose the use of a weighted total least-squares algorithm that takes into account uncertainties in both ordinates and abscissas. The evaluation of the uncertainty associated with Sy, in accordance with the Guide to the Expression of Uncertainty in Measurement, considers the correlation between the parameters involved in its calculation. The implementation of these procedures motivated the development of dedicated software for the computation of tensile parameters from tension-test raw data and for the estimation of their associated uncertainties. To validate the program, developed in MATLAB as a standalone application, we used a set of ASCII data curves that have agreed values for the tensile parameters and which are publicly available at the web site of the National Physical Laboratory of the United Kingdom. Using these curves we demonstrate the validity of the proposed method for the computation of Sy; to validate the uncertainty-evaluation procedure, we use the law of propagation of probability distributions through Monte Carlo simulation. The computational tool, whose capabilities are presented in this work, is currently being used at the Laboratory of Mechanical Testing of the National Institute of Industrial Technology (INTI), in Córdoba, Argentina.
Failure Analysis of a Set of Flapper Valves Under ALT With Alternative Test Device
Authors: Martins J. A. , Ferreira I. , Leite D. , Romão E. C. 
Published: February 2013

Abstract
In search of further understanding and continuous improvement of mechanical products which suffer dynamics loading, several methods of analysis have been applied, among them, computational simulations and laboratorial experiments. This paper aims to describe the failure mechanics of a regular flapper valve and valve reed used on Hermetic Compressors when tested under accelerated test conditions by a special device, created for testing purpose. The results obtained from the valve reed were plotted on a graph, which reveals the endurance under fatigue, versus the device speed/load change. These curves represent the obtained valve reed lifetime by Weibull ALT (accelerated life test) (statistical analysis). The values obtained were analysed using the normality and the probability approaches beyond t-student. The Weibull ALT graph (fatigue lifetime), microscopic analysis by SEM (scanning electron microscope) and EDS (energy dispersive spectroscopy) were performed on the failed valve reed surface as well as on the valve plate seat utilised throughout the tests.
Compressive Behavior of Square-Cell Titanium Honeycomb
Authors: Parsons Ryan , Frink Elizabeth , Lease Kevin , Dubnicka Suzanne 
Published: February 2013

Abstract
The purpose of this study was to experimentally characterize the compressive behavior of square-cell titanium honeycomb cores according to the American Society of Testing and Materials Standard C365-05. By varying the honeycomb cell size and height, as well as the foil thickness, many configurations of titanium honeycomb were manufactured utilizing a laser welding and expansion method. The test matrix consisted of 1080 compression specimens. The compression specimens were split evenly into stabilized and bare tests. At the conclusion of the characterization, a comprehensive statistical analysis was performed on the data. It was determined that the compressive behavior has a strong dependence on the relative density of the honeycomb. The compressive strength was found to be slightly affected by the presence of a stabilizing face sheet, and largely unaffected by specimen core height. The compressive modulus was affected by both the core height and the presence of a face sheet. The compression behavior of the honeycomb was compared with experimental results of honeycomb from existing publications and found to be consistent.
Stressing Lipid Membranes: Effects of Polymers on Membrane Structural Integrity
Authors: Wang Jia-Yu , Cheng Chi-Yuan , Kausik Ravinath. , Chin Jaemin , Han Songi. , Marks Jeremy D. , Lee Ka Yee C. 
Published: February 2013

ABSTRACTDisruption of cell membranes triggers rapid metabolic energy exhaustion, then acute cellular necrosis. Cell membrane dysfunction due to loss of structure integrity is the pathology of tissue death in trauma, muscular dystrophies, reperfusion injuries and common diseases. It is now established that certain PEG-based biocompatible polymers, such as Poloxamer 188, Poloxamine 1107 and PEG, are effective in sealing of injured cell membranes, and thus can prevent acute necrosis if delivered within a few hours after injury. Despite these broad applications of PEG-based polymers for human health, the fundamental mechanisms of how PEG-based polymers interact with cell membranes are still under debate. Here, the effects of PEG-based biocompatible polymers on phospholipid membrane integrity under external stimuli (osmotic stress and oxidative stress) were explored using giant unilamellar vesicles (GUVs) as model cell membranes. Through fluorescence leakage assays and time-lapse fluorescence microscopy, we directly observed that the surface-adsorbed P188 can efficiently inhibits the loss of structural integrity of giant unilamellar vesicles (GUVs) under hypo-osmotic stress. We propose that the adsorption of polymers on the membrane surface is responsible for the cell membrane resealing process, while the insertion of the hydrophobic portion of the polymers increases membrane permeability. To elucidate the mechanism by which hydrophilic polymers help restore membrane integrity while their hydrophobic counterparts disrupt it,1H Overhauser Dynamic Nuclear Polarization (ODNP)-NMR spectroscopy, a newly developed NMR technique that provides unprecedented resolution for differentiating weak surface adsorption versus translocation of polymers to membranes, was employed to sensitively detect polymer-lipid membrane interactions through the modulation of local hydration dynamics in lipid membranes. Our study shows that P188—the most hydrophilic poloxamer known as a membrane sealant—weakly adsorbs onto the membrane surface, yet effectively retards membrane hydration dynamics. Contrarily, P181—the most hydrophobic poloxamer known as a membrane permeabilizer—initially penetrates past lipid headgroups and enhances intrabilayer water diffusivity. Consequently, our results illustrate that the relative hydrophilic/hydrophobic ratio of the polymer dictates its functions. These findings gleaned from local hydration dynamics are well supported by our thermodynamics and fluorescence data.
Ion Implanted Dielectric Films for an Improved Optical and Electronic Silicon Photovoltaic Response
Authors: Shalav Avi , Henderson Christian , Ratcliff Tom , Thomson Andrew 
Published: February 2013

ABSTRACTOver the past few years, ion implanters specifically developed for the high throughput required by the silicon photovoltaic industry, have become commercially available. Recent research and development has focused on the formation of doped surface regions, particularly the formation of selective emitters. In this study we explore two effects of ion implantation into a thermal silicon dioxide passivating/antireflection dielectric. We show evidence that the electronic and optical performance of the layer can be improved via the incorporation of charges created within the dielectric film and the creation of a graded refractive index, minimizing the surface recombination and reflection losses respectively.
Determination of the Density of States on N-type Ptcdi-c13 Organic Thin-film Semiconductor
Authors: Puigdollers J. , Marsal A. , Galindo S. , Carreras P. , Voz C. , Bertomeu J. , Alcubilla R. 
Published: February 2013

ABSTRACTIn this paper we study the density of states in n-type N,N’-ditridecylperylene-3,4,9,10-tetracarboxylic diimide organic semiconductor using two different methods. The first one is based on the temperature dependence of the channel conductance in field-effect transistors. The second one is based on the subgap optical absorption coefficient measured using the Photothermal Deflection Spectroscopy technique. Both techniques allow estimating the distribution of localized states in the band gap of the semiconductor.
Enhanced Electrocaloric Effect in Poly(vinylidene fluoride-trifluoroethylene)-based Composites
Authors: Chen Xiang-Zhong , Qian Xiao-Shi , Li Xinyu , Lu David Sheng-Guo , Gu Haiming , Lin Minren , Shen Qun-Dong , Zhang Qiming 
Published: February 2013

ABSTRACTThe poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) based ferroelectric and relaxor materials have been proved to be good electrocaloric (EC) materials. To further enhance the EC effect in ferroelectric relaxor terpolymer poly(vinylidene fluoride–trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), composites such as polymer-polymer blends and nanocomposites filled with inorganic nanoparticles are fabricated and investigated. It is found that the addition of small amount of filler (such as P(VDF-TrFE) or nano-ZrO2) can increase terpolymer’s crystallinity and enhance its relaxor behavior through interface couplings. The increased crystallinity and enhanced relaxor behavior together result in enhanced electrocaloric effect. The results demonstrate the promise of composite approaches in tailoring and enhancing ECE in the relaxor terpolymers.
Precursor Investigation in the Synthesis of PtPb Nanocatalysts
Authors: Porter Nathan , Wu Hong , Kong Minji , Sun Kai , Kumbhar Amar , Fang Jiye 
Published: February 2013

ABSTRACTIn recent years, platinum-based single crystalline nanoalloys as nanoscale catalysts, such as Pt-M (M = Ni, Co, Fe..etc.), have exhibited improved catalytic performance due to the increase in the surface-to-volume ratio. Some Pt-M nanopolyhedra such as nanocubes and nano-octahedra have been reported with enhanced activity when being used as electrocatalysts. In order to further establish a correlation between the exposed nanocrystal facets (shapes) and their corresponding activities, a pursuit of shape-controlled nanocatalyst synthesis is essential. Although PtPb nanoalloys have been prepared using solution-based methods, few studies have highlighted their catalytic activity as a function of the nanocrystal shape. This work focuses on a modified polyol synthesis technique and an adjustment of the Pb-metal precursor, which serves as a “buffer” in the nucleation stage of the shape-controlled nanoalloy development. Using this developed synthetic strategy, shape-controlled hexagonally close-packed PtPb nanoalloys can be prepared in a one-pot synthesis without additional post-treatment. The as-prepared PtPb nanocrystals demonstrate an improved anode electrocatalytic performance.
Over 12% Light to Hydrogen Energy Conversion Efficiency of Hydrogen Generation from Water: New System Concept, Concentrated Photovoltaic Electrochemical Cell (CPEC)
Authors: Fujii Katsushi , Nakamura Shinichiro , Watanabe Kentaroh , Bagheri Behgol , Sugiyama Masakazu , Nakano Yoshiaki 
Published: February 2013

ABSTRACTEnergy storage is a key technology for establishing a stand-alone renewable energy system. Current energy-storage technologies are, however, not suitable for such an energy system. They are cost ineffective and/or are with low energy-conversion efficiency. Hydrogen generation and storage from water by sunlight is one of these technologies. In this study, a simple concept of hydrogen generation from water by using sunlight, “concentrated photovoltaic electrochemical cell (CPEC)” is proposed. It is experimentally shown that the CPEC operates stably and achieves conversion efficiency from light to hydrogen energy of over 12%.
Optical band-gap of TiO2 nanopowders doped with Al2O3
Authors: Yoshimura Keisuke , Hashimoto Tetsuya , Katsumata Hiroshi 
Published: February 2013

ABSTRACTOptical band-gap and cathode luminescence (CL) properties of anatase TiO2 nanopowders mixed with γ- Al2O3 powders by planetary ball mill were evaluated as a function of a powder mass ratio (x=Al2O3/TiO2) of 0 to 0.5 and their correlation with XRD spectra was also investigated. The optical band-gap of TiO2 increased from 3.36 eV to 3.41eV with increasing milling time (tm) up to 600 min, which was in good agreement with the blue shifts observed in the CL spectra with increasing tm and it was interpreted as a quantum size effect. In addition, the optical band-gap of TiO2 powders mixed with Al2O3 with tm=60min greatly increased from 3.36 eV to 3.48 eV with increasing x up to x=0.5. On the other hand, the optical band-gap of all the powders was decreased by annealing at temperatures above 600°C, which was evidenced by the XRD spectra to be due to the growth of grain size.
Intensity-Modulated Photovoltage Spectroscopy at Evaporated Bulk Heterojunctions of PcCu and C60to Determine the Average Effective Lifetime of Charge Carriers
Authors: Dragässer André , Schlettwein Derck 
Published: February 2013

ABSTRACTOrganic solar cells consisting of Phthalocyaninatocopper (PcCu) as donor and the Buckminsterfullerene C60as acceptor molecule were prepared by physical vapor deposition as planar or bulk heterojunctions. The devices were studied by IV-characterization as well as intensity-modulated photovoltage spectroscopy to determine the average lifetime of charge carriers formed subsequent to light absorption. An increasing charge carrier lifetime was determined for an increasing PcCu-content in the films. Back transfer of electrons at the undesired contact of C60with PEDOT:PSS as well as recombination following hole trapping in interface states in the contact of PcCu with C60or in isolated domains of PcCu are discussed as possible origins.