bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variance of collapse capacity of SDOF systems under earthquake excitations
Authors: Ibarra Luis , Krawinkler Helmut 
Published: January 2011

AbstractThe variance of collapse capacity is an important constituent of probabilistic methodologies used to evaluate the probability of collapse of structures subjected to earthquake ground motions. This study evaluates the effect of ground motion randomness (i.e. record‐to‐record (RTR) variability) and uncertainty in the deterioration parameters of single‐degree‐of‐freedom (SDOF) systems on the variance of collapse capacity.Collapse capacity is evaluated in terms of a relative intensity defined as the ratio of ground motion intensity to a structure strength parameter. The effect of RTR variability on the variance of collapse capacity is directly obtained by performing dynamic analyses of deteriorating hysteretic models for a set of representative ground motions. The first‐order second‐moment (FOSM) method is used to quantify the effect of deterioration parameter uncertainty. In addition to RTR variability, the results indicate that uncertainty in the displacement at the peak (cap) strength and the post‐capping stiffness significantly contribute to the variance of collapse capacity. If large dispersion of these parameters exists, the effect of uncertainty in deterioration parameters on the variance of collapse capacity may be comparable to that caused by RTR variability. Copyright © 2011 John Wiley & Sons, Ltd.
The variation of heat transfer in a two‐sided lid‐driven differentially heated square cavity with nanofluids containing carbon nanotubes for physical properties of fluid dependent on temperature
Authors: Gavili Anwar , Isfahani Taghi Dallali , Sabbaghzadeh Jamshid 
Published: January 2011

AbstractThe behavior of nanofluids containing cylindrical nanoparticles are investigated numerically inside a two‐sided lid‐driven differentially heated square cavity to gain insight into the convective recirculation and flow processes induced by a nanofluid. The physical properties of the base fluid such as viscosity, thermal conductivity and thermal expansion coefficient are, respectively, assumed to be temperature independent (taking the mean temperature of the left and right walls) and temperature dependent. A model is developed to analyze the behavior of nanofluids taking into account the nanoparticle volume fraction whereas the transport equations are solved numerically with finite volume approach using SIMPLEC algorithm. The left and right moving walls are maintained at different constant temperatures while the upper and bottom walls are thermally insulated. The directions of the moving walls were considered in a way that the force and natural convections aid each other. The governing parameter Richardson number was 0.1<Ri<50.0 but due to space constraints only the results for 0.1<Ri<10.0 from fluid flow are presented. It was found that the temperature dependency of physical properties at different Richardson numbers and nanoparticle volume fractions affects the fluid flow and heat transfer in the cavities. Finally, comparisons between the behaviors of the average Nusselt number at the left wall for two cases are presented. Copyright © 2011 John Wiley & Sons, Ltd.
Numerical modeling of the generation of internal waves by uniform stratified flow over a thin vertical barrier
Authors: Houcine H. , Chashechkin Yu. D. , Fraunié P. , Fernando H. J. S. , Gharbi A. , Lili T. 
Published: January 2011

AbstractNumerical simulations of two‐dimensional stratified flow past an obstacle (thin vertical strip) were performed at relatively low Reynolds numbers. A finite differences solver was adopted to simultaneously solve Navier–Stokes equations together with transport equations for salinity (stratifying agent), and the standard Smagorinsky turbulent closure scheme was called in whenever necessary to account for turbulence. The emphases were on the evaluation of code for unsteady stratified flow applications as well as identification of transient and steady internal‐wave processes during flow past obstacles. Simulations were compared with laboratory experiments, where observations were made using a high resolution Schlieren technique and conductivity probes. Blocking was observed upstream of the obstacle, surrounded by near‐zero frequency internal waves, the phase lines of which joined those of lee waves through a transition zone in the proximity of the obstacle. This pattern was preceded by initial transients of the starting flow in which propagating internal waves played a dominant role. Confluence of isopycnals passing over/under the obstacle in the wake led to interesting flow phenomena, including the radiation of internal waves. The numerical simulations were in good agreement with observations, except that some phenomena could not be captured due to resolution issues of either numerical or experimental techniques. The efficacy of the code in point for stratified flow calculations with relevance to the atmosphere and oceans was confirmed. Copyright © 2011 John Wiley & Sons, Ltd.
Compound wall treatment with low‐Re turbulence model
Authors: Rahman M. M. , Siikonen T. 
Published: January 2011

AbstractA generalized treatment for the wall boundary conditions relating to turbulent flows is developed that blends the integration to a solid wall with wall functions. The blending function ensures a smooth transition between the viscous and turbulent regions. An improved low Reynolds number k−ε model is coupled with the proposed compound wall treatment to determine the turbulence field. The eddy viscosity formulation maintains the positivity of normal Reynolds stresses and Schwarz' inequality for turbulent shear stresses. The model coefficients/functions preserve the anisotropic characteristics of turbulence. Computations with fine and coarse meshes of a few flow cases yield appreciably good agreement with the direct numerical simulation and experimental data. The method is recommended for computing the complex flows where computational grids cannot satisfy a priori the prerequisites of viscous/turbulence regions. Copyright © 2011 John Wiley & Sons, Ltd.
Aerodynamic design using the truncated Newton algorithm and the continuous adjoint approach
Authors: Papadimitriou D. I. , Giannakoglou K. C. 
Published: January 2011

AbstractIn this paper, the so‐called ‘continuous adjoint‐direct approach’ is used within the truncated Newton algorithm for the optimization of aerodynamic shapes, using the Euler equations. It is known that the direct differentiation (DD) of the flow equations with respect to the design variables, followed by the adjoint approach, is the best way to compute the exact matrix, for use along with the Newton optimization method. In contrast to this, in this paper, the adjoint approach followed by the DD of both the flow and adjoint equations (i.e. the other way round) is proved to be the most efficient way to compute the product of the Hessian matrix with any vector required by the truncated Newton algorithm, in which the Newton equations are solved iteratively by means of the conjugate gradient (CG) method. Using numerical experiments, it is demonstrated that just a few CG steps per Newton iteration are enough. Considering that the cost of solving either the adjoint or the DD equations is approximately equal to that of solving the flow equations, the cost per Newton iteration scales linearly with the (small) number of CG steps, rather than the (much higher, in large‐scale problems) number of design variables. By doing so, the curse of dimensionality is alleviated, as shown in a number of applications related to the inverse design of ducts or cascade airfoils for inviscid flows. Copyright © 2011 John Wiley & Sons, Ltd.
Does voice go flat? How tenure diminishes the impact of voice
Authors: Avery Derek R. , McKay Patrick F. , Wilson David C. , Volpone Sabrina D. , Killham Emily A. 
Published: January 2011

AbstractAlthough many studies have shown that the opportunity to provide input (voice) leads to more favorable employee reactions, fewer studies have examined the boundary conditions for the effect of voice on worker outcomes. Building upon Greenberg and Strasser's (1986) model of personal control in organizations, we hypothesize that the positive effect of voice on intent to remain will be less pronounced for employees with longer organizational tenures. Converging results of national surveys from the United Kingdom and the United States support the anticipated relationships. It appears the beneficial effects of voice on employee attitudes may decrease as employees accrue tenure with their employer. © 2011 Wiley Periodicals, Inc.
The effects of downsizing on labor productivity: The value of showing consideration for employees' morale and welfare in high‐performance work systems
Authors: Iverson Roderick D. , Zatzick Christopher D. 
Published: January 2011

AbstractAlthough downsizing remains a topic of great interest to scholars and practitioners, little research has examined the link between the process and organizational performance. The current study examines whether organizations showing greater consideration for employees' morale and welfare in the downsizing process experience increased labor productivity. Further, because downsizing diminishes human capital and interferes with an organization's social exchange relationships, we posit that attention to employees' morale and welfare will be particularly important for high‐performance work systems (HPWS) that rely on human capital for competitive advantage. We tested our hypothesis with a sample of organizations that had downsized using survey data matched with secondary data. Results support our prediction that organizations with more extensive HPWS can reduce productivity losses from downsizing by heightening their consideration for employees' morale and welfare. We discuss the implications of these findings. © 2011 Wiley Periodicals, Inc.
Digital Biosensors with Built‐in Logic for Biomedical Applications
Authors: Wang Joseph , Katz Evgeny 
Published: January 2011

AbstractThis article overviews recent advances in biomedical applications of enzyme‐based logic systems, particularly for the analysis of pathophysiological conditions associated with various injuries. Novel biosensors digitally processing multiple biomarker signals produce a final output in the form of YES/NO response through Boolean logic networks composed of biomolecular systems. The biocomputing approach applied to biosensors leads to high‐fidelity biosensing compared to traditional single‐analyte sensing devices. By processing complex patterns of multiple physiological biomarkers, such multi‐signal digital biosensors should have a profound impact on the rapid diagnosis and treatment of diseases, and particularly can provide timely detection and alert of medical emergencies (along with immediate therapeutic intervention). The novel biosensing concept has been exemplified with the systems for logic analysis of various injuries, including soft tissue injury, traumatic brain injury, liver injury, abdominal trauma, hemorrhagic shock, and oxidative stress.
Predicting the form and direction of work role performance from the Big 5 model of personality traits
Authors: Neal Andrew , Yeo Gillian , Koy Annette , Xiao Tania 
Published: January 2011

AbstractThis research examined the prediction of the form and direction of work role performance from the Big 5 model of personality traits. Nine dimensions of work role performance are created by cross‐classifying the form of work role behavior (proficient, adaptive, and proactive) with the level at which that behavior contributes to effectiveness (individual, team, and organizational). The authors collected self‐report measurements of personality from 1447 government employees and supervisor ratings of performance. Openness to experience and agreeableness had opposing effects on individual proactivity – openness was positively related, whereas agreeableness was negatively related to this dimension. Openness to experience also had opposing effects on the form of work role performance – it was positively related to individual and organizational proactivity but negatively related to team and organizational proficiency. Conscientiousness was a stronger predictor of individual task proficiency than the remaining eight dimensions, whereas the reverse was true for neuroticism. Extraversion was negatively related to individual proficiency. Using a broad taxonomy of performance that incorporates a theoretical framework for distinguishing between constructs shows promise for identifying which personality traits are important for which aspects of work role performance. Copyright © 2011 John Wiley & Sons, Ltd.
Water‐stress mitigation by selenium in Trifolium repens L.
Authors: Wang Chang‐Quan 
Published: January 2011

AbstractThis study was designed to examine whether external selenium (Se) may improve the tolerance of Trifolium repens L. to polyethylene glycol (PEG)–induced water deficit, and to determine the physiological mechanisms of the possibly enhanced tolerance. Trifolium repens seedlings were subjected to PEG‐induced water deficit alone or combined with 5 μM Na2SeO4 for 24, 48, and 72 h. During the experimental period, the fresh weight (FW) of T. repens seedlings and the relative water content (RWC) of the leaves decreased gradually, and the chlorophyll concentration increased after 24 and 48 h, but decreased after 72 h. The PEG+Se‐treated plants had higher FW, RWC, and chlorophyll concentration than the PEG‐treated plants. Smaller amounts of thiobarbituric acid‐reactive substances (TBARS) and H2O2 accumulated in PEG+Se‐treated plants than in plants treated only with PEG. The activity of superoxide dismutase (SOD) increased gradually during the water‐deficit period, and Se application promoted SOD activity further. Catalase (CAT) activity remained unchanged after 24 and 48 h and insignificantly increased after 72 h of water deficit, whereas ascorbate peroxidase (APOX) activity increased linearly and glutathione reductase (GR) activity increased slightly over the course of treatment. Whereas the Se application exhibited no effect on the CAT activity, seedlings treated with PEG+Se had higher APOX activity during the whole experimental period and a higher GR activity after 48 and 72 h than PEG‐treated plants. These results suggest that exogenous Se treatment enhanced T. repens tolerance to PEG‐induced water deficit, and this enhancement was related to alleviation of lipid peroxidation and activation of antioxidant enzymes such as SOD, APOX, and GR.
Re‐visiting potassium‐ and phosphate‐fertilizer responses in field experiments and soil‐test interpretations by means of data mining
Authors: Kuchenbuch Rolf O. , Buczko Uwe 
Published: January 2011

AbstractCurrently, potassium (K)‐ and phosphate (P)‐fertilizer recommendation in Germany is based on standardized soil‐testing procedures, the results of which are interpreted in terms of nutrient availability. Although site‐specific soil and plant properties (e.g., clay and carbon content, pH, crop species) influence the relation between soil nutrient content and fertilizer effectiveness, most of these factors are not accounted for quantitatively when assessing fertilizer demand. Recent re‐evaluations of field observations suggest that even for soil nutrient contents well within the range considered to indicate P or K deficiency, fertilizer applications often resulted in no yield increase. In this study, results from P‐ and K‐fertilization trials (in total about 9000 experimental harvests) conducted during the past decades in Germany and Austria were re‐analyzed using a nonparametric data‐mining procedure which consists of a successive segmentation of the data pool in order to elaborate a modified recommendation scheme. In addition to soil nutrient content, fertilizer‐application rates, nutrient‐use efficiency, and site properties such as pH, clay content, and soil organic matter, have a distinct influence on yield increase compared to an unfertilized control. For K, nutrient‐use efficiency had the largest influence, followed by soil‐test K content, whereas for P, the influence of soil‐test P content was largest, followed by pH and clay content. The results may be used in a novel approach to predict the probability of yield increase for a specified combination of crop species, fertilizer‐application rate, and site‐specific data.
Subcellular distribution and chemical forms of chromium in rice plants suffering from different levels of chromium toxicity
Authors: Zeng Fanrong , Zhou Weihui , Qiu Boyin , Ali Shafaqat , Wu Feibo , Zhang Guoping 
Published: January 2011

AbstractThe subcellular distribution and chemical forms of different heavy metals in rice are correlated with their bio‐toxicity. An experiment was conducted to investigate the subcellular distribution and chemical forms of chromium (Cr) in two rice genotypes (Oryza sativa L. cv. Xiushui 113 and cv. Dan K5) differing in Cr accumulation, to understand the mechanisms of Cr toxicity and resistance in rice plants. The results show that Cr in the roots of rice plants exposed to Cr stress was mainly localized in cell walls, whereas Cr in leaves and stems was mainly present in both cell walls and vacuoles, suggesting that both compartments act as important protective barriers against Cr toxicity in rice plants. Although Cr ions in all plant tissues exist predominantly in the forms extracted by 80% ethanol and distilled water, the amount of Cr in the chemical forms extracted by 2% HAc, 0.6 M HCl, and in residues was significantly increased under the highest Cr level (100 μM Cr) compared to the plants grown under lower Cr levels. These results indicate that excess Cr accumulated in rice plants under Cr stress is bound to undissolved or low‐bioavailable compounds, such as undissolved phosphate and oxalate, being beneficial for rice plants to alleviate Cr toxicity. In addition, under the highest Cr level (100 μM), Dan K5 had a higher percentage of Cr in the chemical forms extracted by 2% HAc, 0.6 M HCl, and in residues compared to Xiushui 113 in both stems and leaves, indicating that more Cr ions in shoots of Dan K5 were bound to undissolved or low‐bioavailable compounds, in comparison with those of Xiushui 113. It is evident that the low bioavailability of Cr in the shoots of Dan K5 is related to a high Cr accumulation.
Reintroduction of a native Glomus to a tropical Ultisol promoted grain yield in maize after fallow and restored the density of arbuscular mycorrhizal fungal spores
Authors: Poomipan Phakpen , Suwanarit Amnat , Suwanarit Poonpilai , Nopamornbodi Omsub , Dell Bernard 
Published: January 2011

AbstractMaize (Zea mays L.) is an important crop in central Thailand where fallow is widely practiced and farmers are interested in crop rotation and beneficial soil biota. A pot experiment using a Typic Paleustult (topsoil + subsoil) from the National Corn and Sorghum Research Centre, Nakhonratchasima Province, Thailand was undertaken over three successive crops to evaluate effects of agronomic practices on populations of arbuscular mycorrhizal (AM) fungi and to determine whether reintroduction of a local Glomus was beneficial to maintain maize yield. The three crops and their treatments were: (1) preceding crop: maize grown in all pots; (2) subexperiment 1: agronomic practices [maize, fallow ± soil disturbance, fallow with solarization, non–AM host (cabbage)]; and (3) subexperiment 2: maize ± Glomus sp. 3 at three rates of P fertilization (0, 33, 92 kg P ha–1). The AM‐fungal community was established under the preceding crop. In subexperiment 1, the three fallow treatments decreased (30%–40%) the total AM spore number in the topsoil whereas there was no change under maize or cabbage. Glomus, the dominant genus, showed sensitivity to fallow. In subexperiment 2, inoculation with Glomus sp. 3 enhanced total AM spore number and root colonization when applied following the three fallow treatments. Furthermore, inoculation promoted grain yield; at nil P following fallow ± soil disturbance, at 33 kg P ha–1 following fallow without soil disturbance, and following solarization. Two treatments, maize following maize and maize following cabbage, did not respond to inoculation with Glomus sp. 3. Overall, the results suggest that reintroduction of Glomus sp. 3, a local AM fungus in this soil, may overcome negative effects of fallow and promote effectiveness of P fertilizer. Further work is needed to evaluate the benefits of other indigenous AM species that persist under modern fertilization practices.
Patterns and processes of initial terrestrial‐ecosystem development
Authors: Schaaf Wolfgang , Bens Oliver , Fischer Anton , Gerke Horst H. , Gerwin Werner , Grünewald Uwe , Holländer Hartmut M. , Kögel‐Knabner Ingrid , Mutz Michael , Schloter Michael , Schulin Rainer , Veste Maik , Winter Susanne , Hüttl Reinhard F. 
Published: January 2011

AbstractEcosystems are characterized as complex systems with abiotic and biotic processes interacting between the various components that have evolved over long‐term periods. Most ecosystem studies so far have been carried out in mature systems. Only limited knowledge exists on the very initial phase of ecosystem development. Concepts on the development of ecosystems are often based on assumptions and extrapolations with respect to structure–process interactions in the initial stage. To characterize the effect of this initial phase on structure and functioning of ecosystems in later stages, it is necessary to disentangle the close interaction of spatial and temporal patterns of ecosystem structural assemblages with processes of ecosystem development. The study of initial, less complex systems could help to better identify and characterize coupled patterns and processes.This paper gives an overview of concepts for the initial development of different ecosystem compartments and identifies open questions and research gaps. The artificial catchment site “Chicken Creek” is introduced as a new research approach to investigate these patterns and processes of initial ecosystem development under defined boundary conditions. This approach allows to integrate the relevant processes with related pattern and structure development over temporal and spatial scales and to derive thresholds and stages in state and functioning of ecosystems at the catchment level.