bluuebunny/crossref_metadata_2025_split huggingface dataset:
A stochastic model and synthesis for near‐fault impulsive ground motions
Authors: Yang Dixiong , Zhou Jilei 
Published: October 2014

SummaryThe orientations of ground motions are paramount when the pulse‐like motions and their unfavorable seismic responses are considered. This paper addresses the stochastic modeling and synthesizing of near‐fault impulsive ground motions with forward directivity effect taking the orientation of the strongest pulses into account. First, a statistical parametric analysis of velocity time histories in the orientation of the strongest pulse with a specified magnitude and various fault distances is performed. A new stochastic model is established consisting of a velocity pulse model with random parameters and a stochastic approach to synthesize high‐frequency velocity time history. The high‐frequency velocity history is achieved by integrating a stochastic high‐frequency accelerogram, which is generated via the modified K‐T spectrum of residual acceleration histories and then modulated by the specific envelope function. Next, the associated parameters of pulse model, envelope function, and power spectral density are estimated by the least‐square fitting. Some chosen parameters in the stochastic model of near‐fault motions based on correlation analysis are regarded as random variables, which are validated to follow the normal or lognormal distribution. Moreover, the number theoretical method is suggested to select efficiently representative points, for generating artificial near‐fault impulsive ground motions with the feature of the strongest pulse, which can be used to the seismic response and reliability analysis of critical structures conveniently. Finally, the simulated ground motions demonstrate that the synthetic ground motions generated by the proposed stochastic model can represent the impulsive characteristic of near‐fault ground motions. Copyright © 2014 John Wiley & Sons, Ltd.
Nonlinear rooftop tuned mass damper frame for the seismic retrofit of buildings
Authors: Johnson Jerod G. , Pantelides Chris P. , Reaveley Lawrence D. 
Published: October 2014

SummaryNumerical studies of existing buildings demonstrate the effectiveness of nonlinear/inelastic rooftop tuned mass damper frames (NRTMDF) used as a retrofit for reducing seismic response. The technique utilizes a rooftop penthouse as a tuned mass damper with mass incorporated as the roof deck of the penthouse while targeted nonlinearity and energy dissipation are introduced through buckling restrained braces (BRBs) linking the penthouse mass to the structure below. The writers summarize numerical studies of ten existing buildings modified with a specifically tuned NRTMDF. The studies demonstrate the effectiveness of the technique that stems from elastic and transient inelastic period shifts enabled by the damper coupled with targeted energy dissipation in the penthouse BRBs. Numerical simulations using response nonlinear time‐history analysis techniques show that for many structures and sites, the NRTMDF decreases peak transient response and overall seismic demand of the original structure. The technique also reduces seismic demand on nonstructural elements and components, manifested as reductions in floor acceleration spectra. Energy methods show that the approach enables significant reductions in energy demand on the original structure through the complete earthquake acceleration history. Copyright © 2014 John Wiley & Sons, Ltd.
Ground motion directionality in the 2010–2011 Canterbury earthquakes
Authors: Bradley Brendon A. , Baker Jack W. 
Published: October 2014

SummaryThis paper examines the observed directionality of ground motions in the Christchurch urban area during the 2010–2011 Canterbury, New Zealand earthquakes. A dataset of ground motions recorded at 20 strong motion stations over 10 different earthquake events is utilized to examine the ratios of various response spectral directionality definitions and the orientation of the maximum direction. Because the majority of previous related studies have utilized overlapping ground motion datasets from the NGA database, the results of this study provide a largely independent assessment of these ground motion aspects. It is found that the directionality ratio between the maximum (100th percentile) and 50th percentile orientation‐independent spectral acceleration is similar to that obtained from recent studies. Ground motions from the 4 September 2010 Darfield earthquake are shown to exhibit strong directionality for source‐to‐site distances up to Rrup = 30 km, notably further than results from a previous study, which suggests that such effects are generally limited to Rrup < 5 km. The adopted dataset also offers the unique potential to consider site‐specific effects on directionality ratios and maximum direction orientations; however, in both cases, site‐specific effects are found not to be significant in the observed empirical results. Copyright © 2014 John Wiley & Sons, Ltd.
Pipe–soil interaction for segmented buried pipelines subjected to dip faults
Authors: Erami Mohammad Hossein , Miyajima Masakatsu , Kaneko Shogo , Toshima Toshio , Kishi Shozo 
Published: October 2014

SummaryThis paper describes an investigation of pipe–soil interaction equations suggested by currently used pipeline seismic design codes and the applicability of these equations to segmented pipelines. The results of computer‐aided analyses were compared to results obtained in full‐scale experiments on a segmented ductile iron pipeline 93 mm in diameter and 15 m in length. The pipeline was installed 600 mm below the ground surface in a sandy soil compacted to two different subgrade reaction values. The type of fault considered was a reverse fault with an intersection angle of 60° with the pipeline, and the fault movement was a total of 350 mm in three same steps in the fault trace direction. The findings of this study demonstrate the necessity of considering the nature of soil behavior in pipe–soil interaction equations and the effects of connection joints on the integrated response of pipelines to fault‐induced ground deformations. A new combination of equations constituting a direction‐wise selection from among the equations proposed by currently used guidelines is introduced as a new series to describe pipe–soil interaction for segmented pipelines and is verified using the results of full‐scale experiments. Copyright © 2014 John Wiley & Sons, Ltd.
Enhancement of real‐time hybrid simulation on a shaking table configuration with implementation of an advanced control method
Authors: Günay Selim , Mosalam Khalid M. 
Published: October 2014

SummaryThis paper presents the implementation of Three Variable Control (TVC), an advanced control method, to the existing hybrid simulation (HS) system at the University of California, Berkeley. Motivation, background, and implementation of the TVC are explained together with modifications in the existing HS system. An application, which consists of the real‐time HS of electrical disconnect switches on a shaking table configuration, demonstrates successful implementation of the TVC. The presented application also covers other HS‐related features, namely employment of a three‐dimensional analytical substructure, real‐time HS‐compatible operator‐splitting integration method, and an efficient equation solver for faster computations. Copyright © 2014 John Wiley & Sons, Ltd.
Robust integrated actuator control: experimental verification and real‐time hybrid‐simulation implementation
Authors: Ou Ge , Ozdagli Ali Irmak , Dyke Shirley J. , Wu Bin 
Published: October 2014

SummaryIn this paper, we propose a new actuator control algorithm that achieves the design flexibility, robustness, and tracking accuracy to give real‐time hybrid‐simulation users the power to achieve highly accurate and robust actuator control. The robust integrated actuator control (RIAC) strategy integrates three key control components: loop shaping feedback control based on H∞ optimization, a linear‐quadratic‐estimation block for minimizing noise effect, and a feed‐forward block that reduces small residual delay/lag. The combination of these components provides flexible controller design to accommodate setup limits while preserving the stability of the H∞ algorithm. The efficacy of the proposed strategy is demonstrated through two illustrative case studies: one using large capacity but relatively slow actuator of 2500 kN and the second using a small‐scale fast actuator. Actuator tracking results in both cases demonstrate that the RIAC algorithm is effective and applicable for different setups. Real‐time hybrid‐simulation validation is implemented using a three‐DOF building frame equipped with a magneto‐rheological damper on both setups. Results using the two very different physical setups illustrate that RIAC is efficient and accurate. Copyright © 2014 John Wiley & Sons, Ltd.
Entropy‐based opportunistic spectrum access for cognitive radio networks
Authors: Pirmoradian Mahdi , Adigun Olayinka , Politis Christos 
Published: October 2014

AbstractThis paper proposes an opportunistic spectrum decision scheme based on the weighted residual entropy concept for cognitive radio networks. The proposed scheme maximum entropy channel access selects appropriate spectrum opportunities based on the usefulness of the idle‐channel remaining lifetime estimated through the weighted residual entropy function for the unoccupied channels. The performance of the proposed spectrum decision scheme is evaluated using a wealth of efficiency metrics, namely channel utilisation, channel collision, spectrum handoff rate and collision probability in perfect and imperfect spectrum sensing environments. The probabilities of primary signal detection and false detection are taken into the proposed spectrum hole selection technique. Despite the increasing probability of false detection, simulation results show that this central spectrum decision scheme greatly improves spectrum utilisation when the stated performance metrics were compared with those of known spectrum decision schemes such as random channel access, first‐opportunity channel access and maximum remaining lifetime. Copyright © 2014 John Wiley & Sons, Ltd.
Barium Borosilicate Sealing Glasses Synthesized by a Sol–Gel Process: Chemical Interactions with a Stainless Steel and Gas‐Tightness of a SOFC
Authors: Puig J. , Ansart F. , Lenormand P. , Bailly N. , Georges S. , Dailly J. 
Published: October 2014

AbstractSeveral glasses synthesized by sol–gel route and based on the BaO–B2O3–X–Al2O3–SiO2 (X = CaO, MgO) glass system have been investigated to evaluate their applicability as sealant for solid oxide fuel cell (SOFC). Chemical interactions with K41X stainless steel and hydrogen‐tightness of these materials were evaluated after operations at high temperatures over 1,000 h in air atmosphere. Formation of a new phase at the steel–glass interface and formation of porosity in the glass were observed and determined as critical problems over mid‐term operations. The role of MgO is important to obtain a gas‐tight sealing. Application of the glass paste without binder addition was performed in order to avoid possible residual porosity related problems. The best glass was finally used as sealant between anodic and cathodic compartments in complete SOFCs operated at 760 and at 800 °C. Open circuit voltages and power densities of the cells were recorded during the first hours of operation.
Sintering and Electrical Characterization of La and Nb Co‐doped SrTiO3 Electrode Materials for Solid Oxide Cell Applications
Authors: Sudireddy B. R. , Agersted K. 
Published: October 2014

AbstractSingle‐phase lanthanum and niobium co‐doped strontium titanate (Sr1–3x/2LaxTi0.9Nb0.1O3; x = 0–0.02) ceramics were prepared. Dilatometry in reducing atmosphere showed an increase in the sintering rate and sintered density with an increase in La amount. Microscopy of fractured surfaces of sintered samples showed that the average grain size increased drastically in reducing conditions with increasing La content (and associated A‐site vacancies). By incorporating 2 mol.% La, the electronic conductivity significantly improved from 80 to 135 S cm−1 at 1,000 °C, and even larger improvements were observed at lower temperatures. These observations demonstrate the flexibility in tailoring the microstructure and electronic transport properties by doping small amounts of La into the Nb‐doped SrTiO3 and show that Sr1–3x/2LaxTi0.9Nb0.1O3 is a potential electrode material for solid oxide cells.
Use of Grooved Microchannels to Improve the Performance of Membrane‐Less Fuel Cells
Authors: D'Alessandro J. , Fodor P. S. 
Published: October 2014

AbstractIn this work, the fluid dynamics within a membrane‐less microchannel fuel cell is analyzed computationally. The membrane‐less design is a result of the laminar nature of the fluid flow at small Reynolds numbers, restricting the fuel and oxidant to the vicinity of the corresponding electrodes, without the need of a proton exchange membrane (PEM). However, the performance of such cells is limited by the slow diffusive mass transport near the electrodes, with a large fraction of the reactants leaving the channel without coming in contact with the catalytic surfaces, and thus not being used. We mitigate this problem through the introduction of channel surface modification consisting of angled grooves designed to create convective flows that direct the reactants toward the active surfaces. The grooved structures are optimized for maximum fuel utilization. Operation of this type of cells at Péclet numbers close to 2,500 leads to a performance doubling compared with unmodified cells. Moreover, this increase in efficiency is accompanied by a more uniform distribution of the current across the electrodes, reducing the possibility of hot spots being developed.
Syringe fading as treatment for feeding refusal
Authors: Groff Rebecca A. , Piazza Cathleen C. , Volkert Valerie M. , Jostad Candice M. 
Published: October 2014

AbstractThe efficacy of nonremoval of the cup or spoon as treatment for feeding refusal is dependent on prevention of escape from presentations. In the current investigation, 1 child with feeding refusal escaped presentations during nonremoval of the cup and spoon by clenching his teeth. Therefore, we used a syringe to deposit liquids and solids, increased the volume of liquids and solids in the syringe, and conducted syringe‐to‐cup and syringe‐to‐spoon fading.
Behavioral variability and autism spectrum disorder
Authors: Rodriguez Nicole M. , Thompson Rachel H. 
Published: October 2014

AbstractRestricted and repetitive behavior is a diagnostic characteristic of autism spectrum disorder (ASD). To the extent that the behavior of individuals with ASD can be conceptualized as problems of invariance, our understanding of environmental variables that influence restricted and repetitive behavior may be informed by the basic and applied literature on response variability. The purposes of this paper are (a) to describe how restricted and repetitive behavior can be conceptualized as problems of invariance, (b) to consider the implications of a lack of varied responding for individuals with ASD, (c) to review relevant basic and applied research on response variability, (d) to present methods to address invariant responding for individuals with ASD, and (e) to suggest areas for future research.
Effect of citric acid crosslinking cellulose‐based hydrogels on osteogenic differentiation
Authors: Raucci M. G. , Alvarez‐Perez M. A. , Demitri C. , Giugliano D. , De Benedictis V. , Sannino A. , Ambrosio L. 
Published: October 2014

AbstractUnderstanding the relationships between material surface properties and cellular responses is essential to designing optimal material surfaces for implantation and tissue engineering. In this study, cellulose hydrogels were crosslinked using a non‐toxic and natural component namely citric acid. The chemical treatment induces COOH functional groups that improve the hydrophilicity, roughness, and materials rheological properties. The physiochemical, morphological, and mechanical analyses were performed to analyze the material surface before and after crosslinking. This approach would help determine if the effect of chemical treatment on cellulose hydrogel improves the hydrophilicity, roughness, and rheological properties of the scaffold. In this study, it was demonstrated that the biological responses of human mesenchymal stem cell with regard to cell adhesion, proliferation, and differentiation were influenced in vitro by changing the surface chemistry and roughness. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2045–2056, 2015.
Three‐layered scaffolds for artificial esophagus using poly(ɛ‐caprolactone) nanofibers and silk fibroin: An experimental study in a rat model
Authors: Chung Eun‐Jae , Ju Hyung Woo , Park Hyun Jung , Park Chan Hum 
Published: October 2014

AbstractThe purpose of this study was to determine the feasibility of an artificial esophagus using a three‐layered poly(ε‐caprolactone) (PCL)‐silk fibroin (SF) scaffold in a rat model. The artificial esophagus was a three‐layered, hybrid‐type prosthesis composed of an outer and inner layer of PCL with a middle layer of SF. After depositing the inner layer of the PCL scaffold by electrospinning, the lyophilized middle SF layer was created. The outer layer of PCL was produced following the same procedure used to make the inner PCL layer. Eleven rats were anesthetized using inhaled anesthesia. Circumferential defects of the cervical esophagus (n = 11) were created and reconstructed. Groups of rats were sacrificed after the 1st and 2nd weeks. Three rats died of an esophageal fistula and wound infection. No gross evidence of a fistula, perforation, abscess formation, seroma accumulation, or surrounding soft‐tissue necrosis was observed in the other rats sacrificed after the 1st and 2nd weeks. The artificial esophagus constructs produced complete healing of the circumferential defects by the 2nd week. The composition of the three‐layered artificial esophagus was confirmed histologically to have an outer and inner layer of PCL and a middle layer of SF. The fusion of the PCL‐SF scaffold and the regenerative tissue remained intact. Our study proposes a more practical experimental model for studying a three‐layered PCL‐SF scaffold in the esophagus. However, further studies on circumferential defect reconstruction in a rat model are still required. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2057–2065, 2015.
Internal versus external control of calcium nutrition in kiwifruit
Authors: Montanaro Giuseppe , Dichio Bartolomeo , Lang Alexander , Mininni Alba N. , Nuzzo Vitale , Clearwater Michael J. , Xiloyannis Cristos 
Published: October 2014

AbstractHigher calcium (Ca) concentration in several fleshy fruit including kiwifruit is a pre‐requisite for lower incidence of Ca‐related diseases and improved fruit nutritional value. This review examines the internal and external factors operating along the soil‐to‐fruit pathway that are involved in the uptake and partitioning of Ca in kiwifruit vines. After a brief description of fruit growth and the dynamic of nutrient accumulation during fruit development, the review considers the role of soil Ca concentration and availability, root elongation, mass flow in the apoplast, fruit transpiration, competition between fruit and highly transpiring leaves, weather variables and soil moisture. How fruit morphological and anatomical traits, including skin anatomy, xylem development and hydraulic resistance, influence physiological processes such as transpiration and impact on Ca accumulation is also discussed. The review highlights that approximately 80% of the total Ca content of fruit is accumulated during the early weeks after fruit‐set, suggesting that failure of good fruit Ca nutrition at that time may lead to poor fruit Ca content at harvest. Therefore, based on the analysis of the internal and external factors that influence Ca accumulation, recommendations are made for orchard practices that maximize Ca accumulation in the kiwifruit berry, including optimal pollination, nutrient and irrigation management, and manipulation of canopy architecture.
Ultrabroadband strong light absorption based on thin multilayered metamaterials
Authors: Ding Fei , Jin Yi , Li Borui , Cheng Hao , Mo Lei , He Sailing 
Published: October 2014

AbstractLight absorbers have drawn intensive attention as crucial components for solar‐energy harvesting, thermal emission tailoring, modulators, etc. However, achievement of light absorbers with wide bandwidth remains a challenge thus far. Here, a thin, unprecedentedly ultrabroadband strong light absorber is proposed and experimentally demonstrated, which consists of periodic taper arrays constructed by an alumina–chrome multilayered metamaterial (MM) on a gold substrate. This MM can change from a hyperbolic material to an anisotropic dielectric material at different frequency ranges and the special material features are the fundamental origins of the ultrabroadband absorption. The absorber is quite insensitive to the incident angle, and can be insensitive to the polarization. One two‐dimensional periodic array of 400‐nm height MM tapers is fabricated. The measured absorption is over 90% over almost the entire solar spectrum, reaching an average level of 96%, and remains high (above 85%) even in the longer‐wavelength range till 4 μm. The proposed absorbers open up a new avenue to realize broadband thin light‐harvesting structures.
Chemical shift separation with controlled aliasing for hyperpolarized 13C metabolic imaging
Authors: Shin Peter J. , Larson Peder E.Z. , Uecker Martin , Reed Galen D. , Kerr Adam B. , Tropp James , Ohliger Michael A. , Nelson Sarah J. , Pauly John M. , Lustig Michael , Vigneron Daniel B. 
Published: October 2014

PurposeA chemical shift separation technique for hyperpolarized 13C metabolic imaging with high spatial and temporal resolution was developed. Specifically, a fast three‐dimensional pulse sequence and a reconstruction method were implemented to acquire signals from multiple 13C species simultaneously with subsequent separation into individual images.Theory and MethodsA stack of flyback echo‐planar imaging readouts and a set of multiband excitation radiofrequency pulses were designed to spatially modulate aliasing patterns of the acquired metabolite images, which translated the chemical shift separation problem into parallel imaging reconstruction problem. An eight‐channel coil array was used for data acquisition and a parallel imaging method based on nonlinear inversion was developed to separate the aliased images.ResultsSimultaneous acquisitions of pyruvate and lactate in a phantom study and in vivo rat experiments were performed. The results demonstrated successful separation of the metabolite distributions into individual images having high spatial resolution.ConclusionThis method demonstrated the ability to provide accelerated metabolite imaging in hyperpolarized 13C MR using multichannel coils, tailored readout, and specialized RF pulses. Magn Reson Med 74:978–989, 2015. © 2014 Wiley Periodicals, Inc.