bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mobility management in hybridad‐hocnetworks and the Internet environment
Authors: Denko M. K. 
Published: April 2007

AbstractThe integration of mobilead‐hocnetworks (MANETs) with the Internet provides flexible and multi‐hop communication capability in hybrid wired and wireless networks. Existing architectures for integrating these networks use Mobile IP andad‐hocrouting protocols with fixed gateways. In this paper, we propose a mobility management scheme based on a mobile gateways (MGs) architecture. We designed a buffering mechanism for micro‐ and macro‐mobility management in hybrid networks. The performance of mobility management with optimized handover (MM‐OH), optimized handover with prediction (MM‐OHP) and forced handover (MM‐FH) are evaluated using simulation. Our simulation results show that a buffering mechanism coupled with the hybrid gateway discovery results in a higher packet delivery ratio for MM‐OH and MM‐OHP compared with the MM‐FH scheme. The MM‐OHP scheme has a lower number of handovers compared with the MM‐OH scheme. Moreover, the simulation experiments reveal that the speed of the MG has a relatively higher impact on performance than the speed of mobile nodes. Copyright © 2007 John Wiley & Sons, Ltd.
EZRP: an enhanced zone‐based routing protocol forad‐hocnetworks
Authors: Koyama A. , Arai J. , Barolli L. , Durresi A. 
Published: April 2007

AbstractIn mobilead‐hocnetworks (MANETs), the nodes intercommunicate through single‐hop and multi‐hop paths in a peer‐to‐peer fashion. Intermediate nodes between two pairs of communication nodes act as routers. Thus, the nodes operate both as hosts and routers. The nodes are mobile, so the topology of the network may change rapidly and unexpectedly. One well‐known routing protocol forad‐hocnetworks is the Zone Routing Protocol (ZRP). However, when the protocol searches for a new route, it sends many useless control packets, which increase the network load and decrease the network performance. In this paper, we propose an Enhanced Zone Routing Protocol (EZRP). In EZRP, each node calculates the reliability of the route. In the case of a reliable route, the source node sends the data packet directly to the destination node using that route without route searching. In the case of an unreliable route, the source node searches for a new route again. We show that the network performance can be improved by using EZRP. Copyright © 2007 John Wiley & Sons, Ltd.
Classification and generation of schedules for VLIW processors
Authors: Kessler Christoph , Bednarski Andrzej , Eriksson Mattias 
Published: April 2007

AbstractExact methods for optimal instruction scheduling are gaining importance. They differ, however, considerably in the assumed processor model and in the space of schedules searched for an optimal solution. We identify and analyze different classes of schedules for VLIW processors. The classes are induced by various common techniques for generating or enumerating them, such as integer linear programming or list scheduling with backtracking. In particular, we study the relationship between VLIW schedules and their equivalent linearized forms (which may be used, e.g., with superscalar processors), and we identify classes of VLIW schedules that can be created from a linearized form using VLIW compaction methods that are just the static equivalents of dynamic instruction dispatch algorithms of in‐order and out‐of‐order issue superscalar processors. For example, we study the class of greedy schedules and show that, if all instructions have multiblock reservation tables, it is safe for time optimization to consider greedy schedules only. We also show that, in certain situations, certain schedules generally cannot be constructed by incremental scheduling algorithms that are based on topological sorting of the data dependence graph. We summarize our findings as a hierarchy of classes of VLIW schedules. These results can sharpen the interpretation of the term ‘optimality’ used with various methods for optimal VLIW scheduling, and may help to identify classes that can be safely ignored when searching for an optimal schedule. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient search‐space pruning for integrated fusion and tiling transformations
Authors: Gao Xiaoyang , Krishnamoorthy Sriram , Sahoo Swarup Kumar , Lam Chi‐Chung , Baumgartner Gerald , Ramanujam J. , Sadayappan P. 
Published: April 2007

AbstractCompile‐time optimizations involve a number of transformations such as loop permutation, fusion, tiling, array contraction etc. The selection of the appropriate transformation to minimize the execution time is a challenging task. We address this problem in the context of tensor contraction expressions involving arrays too large to fit in main memory. Domain‐specific features of the computation are exploited to develop an integrated framework that facilitates the exploration of the entire search space of optimizations. In this paper, we discuss the exploration of the space of loop fusion and tiling transformations in order to minimize the disk I/O cost. These two transformations are integrated and pruning strategies are presented that significantly reduce the number of loop structures to be evaluated for subsequent transformations. The evaluation of the framework using representative contraction expressions from quantum chemistry shows a dramatic reduction in the size of the search space using the strategies presented. Copyright © 2007 John Wiley & Sons, Ltd.
NADPH oxidase of human dendritic cells: Role in Candida albicans killing and regulation by interferons, dectin‐1 and CD206
Authors: Donini Marta , Zenaro Elena , Tamassia Nicola , Dusi Stefano 
Published: April 2007

AbstractHuman monocyte‐derived DC express the enzyme NADPH oxidase, responsible for ROS production. We show that Candida albicans did not activate NADPH oxidase in DC, and was poorly killed by these cells. However, Candida‐killing activity increased upon DC stimulation with the NADPH oxidase activator PMA and was further enhanced by DC treatment with IFN‐α or IFN‐γ. This fungicidal activity took place at high DC‐to‐Candida ratio, but decreased at low DC‐to‐yeast ratio, when Candida inhibited the NADPH oxidase by contrasting the assembly of the enzyme on DC plasma membrane. The NADPH oxidase inhibitor diphenyliodonium chloride abrogated the PMA‐dependent DC candidacidal capacity. Engagement of β‐glucan receptor dectin‐1 induced NADPH oxidase activation in DC that was depressed by mannose‐binding receptor CD206 co‐stimulation. Candida was internalized by DC through mannose‐binding receptors, but not through dectin‐1, thus explaining why Candida did not elicit NADPH oxidase activity. Our results indicate that NADPH oxidase is involved in DC Candida‐killing activity, which is increased by IFN. However, Candida escapes the oxidative damage by inhibiting NADPH oxidase and by entering DC through receptors not involved in NADPH oxidase activation.
Blockade of TREM‐2 exacerbates experimental autoimmune encephalomyelitis
Authors: Piccio Laura , Buonsanti Cecilia , Mariani Margherita , Cella Marina , Gilfillan Susan , Cross Anne H. , Colonna Marco , Panina‐Bordignon Paola 
Published: April 2007

AbstractTriggering receptor expressed on myeloid cells (TREM‐2) is a membrane receptor associated with DAP12 that is expressed primarily in myeloid cells, including dendritic cells and microglia, and promotes fusion of osteoclast precursors into multinucleated cells. A rare autosomal recessive condition, Nasu‐Hakola disease (NHD) is associated with loss‐of‐function mutations in DAP12 and TREM‐2. The brain pathology observed in NHD patients suggests that disruption of the TREM‐2/DAP12 pathway leads to neurodegeneration with demyelination and axonal loss. In this study, we have characterized TREM‐2 protein expression on microglia using a newly produced monoclonal antibody directed against the mouse TREM‐2 receptor. We report that TREM‐2 expression is up‐regulated in the spinal cord during both the early inflammatory and chronic phases of myelin oligodendrocyte glycoprotein (MOG)35–55 peptide‐induced experimental autoimmune encaphalomyelitis (EAE). We also demonstrate that TREM‐2 is highly expressed on microglial cells in the central nervous system (CNS) during EAE and that blockade of TREM‐2 during the effector phase of EAE results in disease exacerbation with more diffuse CNS inflammatory infiltrates and demyelination in the brain parenchyma. These results demonstrate a critical role for TREM‐2 during inflammatory responses in the CNS.
An improved response spectrum method for calculating seismic design response. Part 2: Non‐classically damped structures
Authors: Maldonado G. O. , Singh M. P. 
Published: April 2007

AbstractA response spectrum method which combines the analytical advantage of the mode acceleration formulation and the practical advantage of the mode displacement formulation is developed for seismic response calculation of non‐classically damped structures. It reduces the error associated with the truncation of the high frequency modes without explicitly using them in the analysis. The method is especially effective for calculating the response of stiff structural systems and also for calculating the response quantities which are strongly affected by high frequency modes. Even with flexible structures, it is shown to provide more accurate response results than the results obtained with the mode displacement approach.
Effects of ground motion spatial variability on the response of cable‐stayed bridges
Authors: Nazmy Aly S. , Abdel‐Ghaffar Ahmed M. 
Published: April 2007

AbstractIn order to extend our knowledge of the performance of long‐span bridges under earthquake loading the effects of spatial variability of ground motion on the structural response of cable‐stayed bridges are studied; the result can be useful to practising bridge engineers. The multiple‐support excitation analysis is described, and two three‐dimensional models representing the modern and future trends in cable‐stayed bridge design are utilized to shed some light on salient features of the seismic response characteristics of these modern bridges. In addition, models of steel‐ and concrete‐design alternates of an existing bridge are considered. Differential ground motion records (obtained from dense instrument arrays) are used as synchronous and non‐synchronous support motions; in addition, non‐dispersive seismic waves travelling along the bridge are considered. The bridge response to non‐uniform ground motion is compared to its response to uniform input. An overview of the unique dynamic characteristics of these cable‐supported bridges is also presented. Finally, the study, which was used in the seismic design of several existing cable‐stayed bridges in U.S. and Canada, indicates that the response quantities may increase substantially from the non‐uniform input ground motion, especially for more rigid bridges and for bridges having different dynamic properties of the local soils at the supporting points, but the degree of increase depends upon the specific problem, in particular upon the aspects of span length, rigidity and structural redundancy. Thus, the response to non‐uniform input ground motion should be examined for these bridges.
A unified mode combination theory for stationary response of structural systems
Authors: Igusa Takeru 
Published: April 2007

AbstractA general theory of mode combination is developed for structural systems subjected to stationary stochastic excitation. The analysis begins with a brief review of a mode combination expression for first‐order systems. Then, new fundamental properties of this result are developed. These properties are used to establish common analytical foundations and make new extensions of previously developed mode combination results for under‐critically damped, classically damped, cascaded and non‐linear structures. In the second part of the paper, an efficient and general mode combination method is developed for cascaded structures. It is shown how the unified mathematical framework established herein can be applied to cascaded structures composed of different types of substructures without the need to derive separate mode combination expressions.
The system damping, the system frequency and the system response peak amplitudes during in‐plane building‐soil interaction
Authors: Todorovska M. I. , Trifunac M. D. 
Published: April 2007

AbstractThe system damping, the system frequency, the relative building response and the base rocking response peak amplitudes are studied, as those depend on the building mass and height, the flexibility of the soil, the structural damping, the type of incident waves and their angle of incidence. A linear two‐dimensional model is used, which assumes the soil to be a homogeneous isotropic half‐space, the foundation supporting the building to be a rigid embedded cylinder, and in which the building model is an equivalent single‐degree‐of‐freedom oscillator. The system frequency and the system damping ratio are determined by measuring the width and the frequency of the peak in the transfer function of the oscillator relative response, using the analogy with the half‐power method for a single‐degree‐of‐freedom fixed‐base oscillator. Previous similar studies are for dynamic soil‐structure interaction only, and for simplified models in which the stiffness of the soil and the damping due to radiation are represented by springs and dashpots. The study in this paper differs from the previous studies in that the wave passage effects (or the kinematic interaction) are also included, and that no additional simplifications of the model are made. Results are shown for excitation by plane P‐ and SV‐waves.
Response spectrum analysis of structures subjected to spatially varying motions
Authors: Berrah Mounir , Kausel Eduardo 
Published: April 2007

AbstractAn important aspect of earthquake loads exerted on extended structures, or structures founded on several foundations, is the spatial variability of the seismic motion. Hence, a rigorous earthquake resistant design of lifeline structures should account for the spatial character of the seismic input, at least in an approximate way.A procedure is proposed which enables addressing the problem of multiply supported structures, subjected to imperfectly correlated seismic excitations, by means of an extension to the response spectrum method. A modified response spectrum model is developed for the design of extended facilities subjected to single and multicomponent ground motion. The modification procedure is based on adjusting each spectral value of the given design response spectrum by means of a correction factor, which depends on the structural properties and on the characteristics of the wave propagation phenomenon. Finally, the theoretical model is validated through digital simulation of seismic ground motion, whereby model predictions are found to be in good agreement with exact results.
Predictive control of base‐isolated structures
Authors: Inaudi J. , López‐Almansa F. , Kelly J. M. , Rodellar J. 
Published: April 2007

AbstractA control design for absolute motion reduction of base‐isolated structures subjected to earthquake excitation is presented herein. The control objective is to provide a vibration‐free environment for sensitive equipment protection. Predictive control theory is used for the control design. This theory allows the designer to handle time delays generated by the dynamics of actuators. The study reported herein demonstrates, by numerical simulation, the efficacy of this controller in reducing acceleration response in the superstructure in the presence of delays. Stability analysis, frequency response and response to ground motion excitation are developed to assess the characteristics of the controller.
Design of torsionally unbalanced structural systems based on code provisions I: Ductility demand
Authors: Tso W. K. , Zhu T. J. 
Published: April 2007

AbstractUsing a three element single mass model, this paper presents the ductility demands on the elements of torsionally unbalanced systems when subjected to strong earthquake shaking. Torsionally unbalanced systems based on nine structural configurations are considered, ranging from torsionally stiff systems with the centre of rigidity (CR) centrally located to torsionally flexible systems with CR eccentrically located. The strength of the elements is designed based on the Canadian and New Zealand codes, and the Uniform Building Code (UBC) of the United States. It is shown that all three codes can limit the ductility demands on the elements to that of a similar but torsionally balanced system when the system is torsionally stiff. However, substantial additional ductility demands on the element at the stiff edge of the system exist for torsionally flexible systems when the New Zealand code or UBC is used. The large ductility demand is caused by the low strength of the stiff‐edge element permitted by these codes.
Orientation error estimation of buried seismographs in array observation
Authors: Yamazaki Fumio , Lu Lin , Katayama Tsuneo 
Published: April 2007

AbstractArray observation is an efficient tool to investigate various characteristics of earthquake ground motion. However, seismographs used in arrays may involve unexpected errors in their orientations. Methods of orientation error estimation were developed in three‐dimensional space by comparing recorded ground motions at a reference point with those at a checking point. A maximum cross‐correlation method and a maximum coherence method were proposed and their accuracy was demonstrated. The earthquake ground motions recorded in the Chiba array and in two other arrays were used in numerical examples. Non‐trivial orientation errors were detected for all these arrays. The cross‐correlation coefficients and the coherence values between two points increased significantly by correcting the estimated orientation errors.
Dynamic characteristics of multiple substructures with closely spaced frequencies
Authors: Xu Kangming , Igusa Takeru 
Published: April 2007

AbstractThis paper considers a main structure supporting a large number of substructures. The substructures have closely spaced natural frequencies, and the combined main structure/multiple substructures system is subjected to harmonic or wide‐band forces. The goal is to characterize the effects of the substructures on the response of the main structure.A special, fundamental case is studied in detail, where the substructures are oscillators with equal stiffnesses and equally spaced natural frequencies. The exact response expressions for the combined system are in terms of a complicated rational polynomial. However, by taking the limit where the number of substructures becomes large, the response expressions reduce to simple, physically meaningful results. It is found that the multiple substrutures are equivalent to a single viscous damping which is added to the damping of the main structure. An example illustrates how the results can be applied to passive vibration control of large structures.
Transient elastodynamic analysis by time domain bem in cylindrical coordinates
Authors: Lei Z. X. , Tham L. G. , Cheung Y. K. 
Published: April 2007

AbstractA time domain boundary element in a cylindrical coordinate system is developed for the analysis of wave propagation in a half space. The integral formulation is based on Graffi's dynamic reciprocal theorem and Stokes' fundamental solutions. The field quantities (displacements and tractions) are expressed as products of Fourier series in the tangential direction and linear polynomials in the other spatial directions. Gaussian integration is used to integrate the non‐singular parts of the integral equations, whereas the integration of the singular components, which are either of order 1/r or 1/r2, is handled by special numerical schemes. In the time marching aspect, the field quantities are assumed to vary linearly in the temporal direction as well.Examples for wave propagation due to various forms of surface excitations are reported to demonstrate the accuracy of the method.
One‐dimensional modelling of the non‐linear far field in soil–structure‐interaction analysis
Authors: Wolf John P. , Paronesso Antonio 
Published: April 2007

AbstractIn a bounded domain elasto‐plastic wave propagation can be modelled accurately using the finite‐element method. As is even the case for an elastic analysis, an unbounded domain, e.g. a semi‐infinite soil or fluid, can, however, not be represented in this manner, as any spatial discretization has to be avoided. For one‐dimensional wave propagation with a bi‐linear elasto‐plastic material law involving one stress component an analytical solution exists. The latter is used in modelling the non‐linear far field of an unbounded medium using a rigorous bookkeeping procedure of the generated elastic and plastic waves propagating in both directions. The need for a non‐linear model of the far field arises, as in a two‐dimensional representation of soil‐structure interaction the surface waves do not decay.
A FE–BE method for dynamic analysis of dam–foundation–reservoir systems in the time domain
Authors: Touhei Terumi , Ohmachi Tatsuo 
Published: April 2007

AbstractBy coupling FEM and BEM, a numerical method was developed for dynamic response analyses of dam–foundation–reservoir systems in the time domain. During formulation, the weighted residual procedure was applied to the coupling of several equations of motion for solid and fluid in the FE and BE regions, and an algorithm similar to the Newmark beta procedure was finally obtained. The algorithm is advantageous in that it takes into account all the effects of dam–foundation, dam–reservoir and reservoir–foundation interactions, as well as of the absorption of both elastodynamic and hydrodynamic waves at the boundaries of the foundation and the reservoir. To demonstrate the validity of the present method, the impulsive response of a dam–foundation–reservoir system was calculated using the algorithm, and showed a good agreement with the existing results obtained by other researchers.
Inelastic response and design criteria of plan‐wise asymmetric systems
Authors: De Stefano Mario , Faella Giuseppe , Ramasco Roberto 
Published: April 2007

AbstractThe study of the torsional response of buildings in the inelastic range of behaviour is of great interest since the ability of structures to resist strong earthquakes mainly relies on their ductility and capacity for energy dissipation. Furthermore, an examination of the performance of structures during past earthquakes demonstrates that plan‐asymmetric buildings suffered greater damage due to torsional response. The paper deals with this subject by analysing a model which idealizes a one‐storey building with resisting elements oriented along two perpendicular directions. In addition to the parameters of the elastic behaviour, the inelastic system response depends on full yield capacity and plan‐wise strength distribution. The influence of the criterion adopted for the design of resisting elements on local ductility demand and damage has been evaluated by parametric analysis. In particular, a comparison has been carried out between systems with equal design levels for all elements and systems with design levels dependent on the element location. For a given elastic behaviour and total capacity, the strength distributions in plan have been defined which minimize ductility demand and structural damage. Finally, based on these findings, responses from models designed according to several seismic codes have been compared.