bluuebunny/crossref_metadata_2025_split huggingface dataset:
A flatness based view on state controllability of simple hyperbolic distributed parameter systems. A string with interior point mass.
Authors: Woittennek Frank 
Published: December 2011

AbstractA flatness based approach to the analysis of state controllability of systems described by one or more boundary coupled 1D hyperbolic second order equations is analyzed on the basis of a nontrivial example. Introducing a state which corresponds to the parametrization of the solution trajectories by a so called flat output and establishing the state transformation to the original state space the controllability problem reduces to a simple interpolation problem. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stabilization of unknown nonlinear systems using a cognition‐based framework
Authors: Shen Xi , Zhang Fan , Söffker Dirk 
Published: December 2011

AbstractThis paper considers an adaptive control method based on a cognition‐based framework to stabilize unknown nonlinear systems. In order to fulfill the task of stabilization, neither the information about the systems dynamical structure nor the knowledge about system physical behaviors, but the system states, which are assumed as measurable, are required. The structure of the proposed controller consists of three parts. The first part is based on a recurrent neural network (RNN) to be used for local identification of the unknown nonlinear system in real time. The network can be utilized as system characteristics, which is further used to design the controller within the third part. In the second part, the set of the given input values leading to stable behavior of the closed‐loop system will be calculated numerically with a geometrical criterion based on a suitable definition of quadratic stability. In the third part, a suitable control input value is chosen accordingly to a time‐relevant criteria from the set of input values generated in the second part of the controller. These three parts and their internal connections are arranged within a so‐called cognition framework. The proposed cognitive controller is able to gain useful knowledge (with local validity) and define autonomously a suitable control input with respect to the requirements of the time‐relevant criteria. Numerical examples are shown to demonstrate the successful application and performance of the method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Short communication: Dimensionality reduction of curvelet sparse regularizations in limited angle tomography
Authors: Frikel Jürgen 
Published: December 2011

AbstractWe investigate the reconstruction problem for limited angle tomography. Such problems arise naturally in applications like digital breast tomosynthesis, dental tomography, etc. Since the acquired tomographic data is highly incomplete, the reconstruction problem is severely ill‐posed and the traditional reconstruction methods, such as filtered backprojection (FBP), do not perform well in such situations. To stabilize the inversion we propose the use of a sparse regularization technique in combination with curvelets. We argue that this technique has the ability to preserve edges. As our main result, we present a characterization of the kernel of the limited angle Radon transform in terms of curvelets. Moreover, we characterize reconstructions which are obtained via curvelet sparse regularizations at a limited angular range. As a result, we show that the dimension of the limited angle problem can be significantly reduced in the curvelet domain. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale total variation regularization in image restoration
Authors: Dong Yiqiu , Hintermüller Michael , Rincon‐Camacho M. Monserrat 
Published: December 2011

AbstractA total variation model for image restoration is introduced. The model utilizes a spatially dependent regularization parameter in order to enhance image regions containing details while still sufficiently smoothing homogeneous features. A local variance estimator is used to automatically adjust the regularization parameter. A generalized hierarchical decomposition of the restored image is integrated to the algorithm in order to speed‐up the performance of the update scheme. The corresponding subproblems are solved by a superlinearly convergent algorithm based on Fenchel‐duality and inexact semismooth Newton techniques. Numerical tests illustrate the performance of the algorithm. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Multi‐level Voting Scheme of Kernel Fisher Discriminant Classifiers for Liver Fibrosis Identification in Ultrasound Images
Authors: Salca Victor‐Eugen , Gordan Mihaela , Vlaicu Aurel 
Published: December 2011

AbstractUltrasound imaging remains important for computer aided medical diagnosis. The assessment of hepatic fibrosis from ultrasound images has been investigated in recent works. Fibrosis modifies the liver texture; this is reflected in the hepatic ultrasound image. The existing works report the extraction of different texture features from small regions of interest (ROIs) in the hepatic ultrasound image used as inputs to machine learning classifiers. As the obtained accuracies are generally moderate (85‐90%), new texture descriptors and classifier schemes are still investigated. Here we assess the performance of the Kernel Fisher Discriminant (KFD) due to its success in other similar tasks. KFD allows an implicit texture discrimination learning from a set of texture samples. The novelty of our solution is its use in a multi‐level scheme. With a training set of ultrasound liver image ROIs of 64×64 pixels, we generate 3 training image sets, one at full size and the others by the decomposition of ROIs into 32×32 and 16×16 pixels blocks. Three KFD classifiers are trained. In the classification phase, each test ROI is classified and the result is obtained by a majority voting scheme. The accuracy of the proposed solution is 89%, on the level of the state of the art, and it can probably be improved by increasing the training set. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An hp‐Efficient Residual‐Based A Posteriori Error Estimator for Maxwell's Equations
Authors: Bürg Markus 
Published: December 2011

AbstractWe present a residual‐based a posteriori error estimator for Maxwell's equations in the electric field formulation. The error estimator is formulated in terms of the residual of the considered problem and we state upper and lower bounds in terms of the energy error of the computed solution for the estimator. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cellular Automata (CA) for Simulations of Complex Geothermal Reservoirs
Authors: Srisupattarawanit Tarin , Ostermeyer George‐Peter 
Published: December 2011

AbstractThe exploitation of geothermal power is a renewable energy source with great potential in future. But the exploration and development of deep geothermal energy is connected with high cost and risk. These require a reliable functionality of geological heat exchanger. However the geothermal reservoirs are really complicated as phenomena and concrete downhole data are not completely discovered at present. In order to simulate them, complex modelings combined with different time scale are necessary. Recently, the cellular automata (CA) method is being developed and widely used for solving many complex problems in different fields. Here we introduced CA method combined with Navier‐Stoke equation and heat transfer; the domains of reservoirs are initially discretized into many lattice cells. The different cell type and their physical properties (e.g. water cell, porous cell, etc.) are introduced. Thermodynamically correct computation and computing fluid flow in different formations are performed. The paper will give some computational results, showing the efficiency and accuracy of this method, in order to complete the phenomena of complex geothermal problem. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selfadjoint Schrödinger operators on the half‐space with compactly supported Robin boundary conditions
Authors: Behrndt Jussi , Kühn Christian , Rohleder Jonathan 
Published: December 2011

AbstractSchrödinger differential operators on a half‐space with compactly supported Robin boundary conditions are studied. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Note on Homogenization of Ordinary Differential Equations with Delay Term
Authors: Waurick Marcus , Kaliske Michael 
Published: December 2011

AbstractAn approach to homogenization of delay differential equations is proposed. Assuming some dependence between the delay and the micro‐scale, the effective equation is explicitly computed. The effective equations of homogenization of delay equations and the respective equations without delay are compared. In either cases, the effective equation is of integro‐differential‐type. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Expansion of random field gradients using hierarchical matrices
Authors: Busch Ingolf , Ernst Oliver G. , Ullmann Elisabeth 
Published: December 2011

AbstractWe present two expansions for the gradient of a random field. In the first approach, we differentiate its truncated Karhunen‐Loève expansion. In the second approach, the Karhunen‐Loève expansion of the random field gradient is computed directly. Both strategies require the solution of dense, symmetric matrix eigenvalue problems which can be handled efficiently by combining hierachical matrix techniques with a thick‐restart Lanczos method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic analysis of dielectric elastomer actuators
Authors: Xu Bai‐Xiang , Müller Ralf , Klassen Markus , Gross Dietmar 
Published: December 2011

AbstractDielectric elastomer actuators (DEAs) with a typical sandwich structure of electrode‐elastomer‐electrode arrangement provide large deformation. DEAs outperform most large displacement actuators in terms of light weight, low cost, and high efficiency. The actuation mechanism of DEAs relies primarily on the electrostatic force or the Maxwell stress which is due to the reaction of material polarization in an electric field. By a dynamic nonlinear electromechanical continuum model implemented with the finite element method, the dynamic response of a homogeneous DEA is studied. Results show that the actuation magnitudes can be increased when the frequency of the applied electric field approaches to the eigenfrequency of the DEAs. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Two‐Phase Steels based on Statistically Similar Representative Volume Elements
Authors: Balzani Daniel , Schröder Jörg , Brands Dominik 
Published: December 2011

AbstractAn increasing number of engineering structures in the fields of light weight constructions or automotive applications makes use of advanced high‐strength steels. To optimize the overall mechanical behavior computer simulations taking into account the micro‐heterogeneity of these materials have been becoming the major tool. Direct micro‐macro‐transition procedures, also known as the FE2‐method, provide a suitable numerical framework. The main problem of these methods applied to large random microstructures turns out to be the high computational cost with respect to both, the amount of memory and the computation time. In this context the definition of a representative volume element (RVE) plays an important role. Therefore, we focus on the construction of statistically similar RVEs (SSRVEs), which are characterized by a much less complexity than usual random RVEs and which represent still the mechanical response of the real material. For the construction of these SSRVEs we select several statistical measures of the microstructure of a two‐phase steel and assume them to be as similar as possible to the ones computed for the SSRVE. These measures are included in a least‐square functional, which has to be minimized. The accuracy of this method is presented by some representative numerical simulations, where the response of the real microstructure of the considered two‐phase steel and the SSRVEs is compared to each other. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatial dispersion and binomial sequential sampling for the potato psyllid (Hemiptera: Triozidae) on potato
Authors: Butler Casey D , Trumble John T 
Published: December 2011

AbstractBACKGROUND: The potato psyllid is a serious pest of potatoes. Sampling plans on potatoes for the potato psyllid have yet to be developed, thus the authors' objectives were (1) to determine the most efficient within‐plant sampling unit, (2) to determine the spatial dispersion of potato psyllids in potato fields and (3) to develop a binomial sequential sampling plan for this pest.RESULTS: Significantly more potato plants were infested with potato psyllids on the edges of the field, and significantly more plants were infested with psyllids on the ‘top’ and ‘middle’ of the potato plant. Significantly more psyllids were also found on the undersides of leaves. The potato psyllid has an aggregated distribution in potato fields. Binomial sequential sampling plans were developed for three action thresholds representing 0.5, 1 and 5 psyllids per plant. The average sample numbers for these action thresholds were between 12 and 16 samples, depending on the action thresholds. However, based on the shape of the operating characteristic curve, the 0.5 and 1 sampling plans were more reliable than the 5 psyllids per plant plan.CONCLUSION: The binomial sequential sampling plans are useful for detecting potato psyllids at low levels of infestation, which will be useful for pest management purposes. Copyright © 2011 Society of Chemical Industry
Designer repellents: combining olfactory, visual or taste cues with a secondary repellent to deter free‐ranging house sparrows from feeding
Authors: Clapperton Barbara Kay , Porter Richard ER , Day Tim D , Waas Joseph R , Matthews Lindsay R 
Published: December 2011

AbstractBACKGROUND: Repellents may prevent bird pests from eating crops or protect non‐target birds from eating harmful substances. The feeding behaviour of free‐ranging house sparrows (Passer domesticus) presented with wheat treated with the secondary repellent anthraquinone (AQ), paired with visual and/or olfactory and taste cues, was recorded in a series of trials. The aim was to determine the suitability of repellent combinations for preventing birds from consuming pest baits.RESULTS: Anthraquinone significantly reduced wheat consumption. The addition of cinnamon oil did not reduce consumption further, but the addition of either a blue colour or d‐pulegone enhanced repellency. Green wheat was consumed more than blue wheat. In a multichoice test, the sparrows did not differentiate between low and high concentrations of AQ on blue‐dyed wheat. With treatments on separate tables, the higher concentration was more repellent. Additional olfactory/gustatory cues palatable to pest mammals did not make the AQ‐treated wheat more or less acceptable to sparrows. AQ‐treated blue wheat with/without cinnamon oil was more repellent than green wheat with cinnamon oil, a colour/odour combination typically used for pest baits in New Zealand.CONCLUSIONS: These data demonstrate the potential of combining the secondary repellent AQ with additional salient cues for modifying the feeding behaviour of sparrows. Copyright © 2011 Society of Chemical Industry
Second Moment Reliability Evaluation vs. Monte Carlo Simulations for Weld Fatigue Strength
Authors: Lorén Sara , Svensson Thomas 
Published: December 2011

Monte Carlo simulations have become very popular in industrial applications as a tool to study variational influences on reliability assessments. The method is appealing because it can be done without any statistical knowledge and produces results that appear very informative. However, in most cases, the information gathered is no more than a complicated transformation of initial guesses because the statistical distributions of the dominating variational influences are unknown. The seemingly informative result may then be highly misleading, in particular, when the user lacks sufficient statistical knowledge. Instead, in cases where the input knowledge of the distributional properties is vague, it may be better to use a reliability method based on the actual knowledge, often not more than second moment characteristics. This can easily be done by using a method, based on variances, covariances, and sensitivity coefficients.Here, a specific problem of fatigue life of a welded structure is studied by (i) a Monte Carlo simulation method and (ii) a second moment method. Both methods are evaluated on a fatigue strain–life approach and use experimental data showing variation in weld geometry and material strength parameters.The two methods are compared and discussed in view of the engineering problem of reliability with respect to fatigue damage. Copyright © 2011 John Wiley & Sons, Ltd.
Service selection and horizontal multi‐sourcing in process‐oriented capability outsourcing
Authors: Ukor Roland , Carpenter Andy 
Published: December 2011

SUMMARYProcess‐oriented capability outsourcing is a type of B2B collaboration in which one organisation outsources parts of its business process to other organisations known as service providers. Current models and solution approaches for service selection in process‐oriented capability outsourcing do not provide support for horizontal multi‐sourcing—the ability to dynamically outsource a business capability to multiple independent service providers. This paper presents a new problem model for service selection based on the notion of request tokens, and evaluates three solution approaches to the problem: integer programming, tree‐search heuristic and genetic algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Flex‐eWare: a flexible model driven solution for designing and implementing embedded distributed systems
Authors: Jan Mathieu , Jouvray Christophe , Kordon Fabrice , Kung Antonio , Lalande Jimmy , Loiret Frédéric , Navas Juan , Pautet Laurent , Pulou Jacques , Radermacher Ansgar , Seinturier Lionel 
Published: December 2011

SUMMARYThe complexity of modern embedded systems increases as they incorporate new concerns such as distribution and mobility. These new features need to be considered as early as possible in the software development life cycle. Model driven engineering promotes an intensive use of models and is now widely seen as a solution to master the development of complex systems such as embedded ones. Component‐based software engineering is another major trend that gains acceptance in the embedded world because of its properties such as reuse, modularity, and flexibility.This article proposes the Flex‐eWare component model (FCM) for designing and implementing modern embedded systems. The FCM unifies model driven engineering and component‐based software engineering and has been evaluated in several application domains with different requirements: wireless sensor networks, distributed client/server applications, and control systems for electrical devices. This approach highlights a new concept: flexibility points that arise at several stages of the development process, that is, in the model (design phase), in the execution platform, and during the execution itself. This flexibility points are captured with model libraries that can extend the FCM. Copyright © 2011 John Wiley & Sons, Ltd.
Catalytically propelled micro‐/nanomotors: how fast can they move?
Authors: Gao Wei , Sattayasamitsathit Sirilak , Wang Joseph 
Published: December 2011

AbstractSynthetic micro‐/nanomotors represent one of the most exciting challenges facing nanotechnology and hold considerable promise for diverse future applications. This review discusses different strategies to improve the speed of the catalytic nanomotors, summarizing and comparing the maximum absolute and relative speeds obtained with different catalytically propelled micro‐/nanomotors. Remarkably ultrafast nanowires and microtube engines, with speeds of 60 and 375 body lengths s−1, respectively, have been developed recently. Achieving such amazingly high speed and power has been accomplished through rational optimization of key factors governing the propulsion behavior, including composition of the motor and fuel, the motor morphology and various external stimuli. We hope that our discussion will serve as a guide to the rational design of even faster and more powerful catalytically propelled fuel‐efficient micro‐/nanomotors, with speed limits that are limited only by our imagination. DOI 10.1002/tcr.201100031
Short‐circuit analysis of a doubly fed induction generator wind turbine with direct current chopper protection
Authors: Sulla F. , Svensson J. , Samuelsson O. 
Published: December 2011

ABSTRACTModern doubly fed induction generator (DFIG) wind turbines can ride through a symmetrical fault in the network by using a chopper protection on the direct current (DC) link without triggering a crowbar protection. A novel method to model the DC link system of such wind turbines as an equivalent resistance during symmetrical faults is presented in this paper. The method allows looking at the DFIG with chopper protection as to one with an equivalent crowbar protection and, hence, to apply to the former type of DFIG short‐circuit calculation methods developed for a DFIG with crowbar protection. This may be a valid help in short‐circuit calculations, for example, for protection settings. It also allows simulating for short‐circuit studies a DFIG with chopper protection, often not available in a standard power system simulation software, by using an equivalent DFIG with crowbar protection, which is a standard model in power system simulation software. The results for the short‐circuit current obtained through the proposed method are compared with simulations of a detailed model of a DFIG with chopper protection under different conditions, which showed good agreement. It is also shown that the DFIG with chopper protection delivers lower short‐circuit current than a DFIG with standard crowbar protection, especially for low initial loading. Copyright © 2011 John Wiley & Sons, Ltd.
Safety profile of Alzheimer's disease populations in Alzheimer's Disease Neuroimaging Initiative and other 18‐month studies
Authors: Henley David B. , Sundell Karen L. , Sethuraman Gopalan , Siemers Eric R. 
Published: December 2011

AbstractBackgroundDemonstration of a disease‐modifying effect of a therapeutic agent on Alzheimer's disease (AD) requires a trial lasting for at least 18 months. An understanding of expected rates of adverse events (AEs), overall discontinuations, and discontinuations due to AEs, serious AEs, and deaths would be useful in planning such trials.MethodsWe examined safety information for patients taking placebo from five published 18‐month AD trials and for patients from the Alzheimer's Disease Neuroimaging Initiative study.ResultsAEs reported consistently across multiple studies were dyspnea (occurring in 5.3%–5.8% of patients), headache (4.0%–5.5%), constipation (4.3%–4.7%), nausea (2.0%–5.8%), joint swelling (3.6%–3.7%), vomiting (3.6%–3.7%), and anxiety (3.2%–3.6%). Larger multinational studies, as compared with smaller studies with fewer sites and geographies, demonstrated greater overall discontinuations (24.6%–33.0% vs 8.2%–21.0%) and greater discontinuations due to AEs (9.5%–11.6% vs 2.7%–3.2%). Rates of death (1.8%–2.4%) and SAEs (19.9%–21.2%) were consistent across 18 month published studies and in ADNI; fall was the most common SAE (2.6%–4.0%) where SAEs were reported.ConclusionsIn general, comparable types of AEs, frequency of deaths, and serious AEs were seen for patients taking placebo in five randomized, controlled 18‐month AD trials and in Alzheimer's Disease Neuroimaging Initiative, whereas rates of discontinuations were more variable. Evaluation across studies was complicated by inconsistent methods of reporting safety information. Evaluation of large databases of placebo patients from therapeutic AD trials is needed to further enhance the understanding of expected safety outcomes in clinical trials of AD patients.