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We consider a structural approach to the consensus building problem in multi‐group multi‐layer (MGML) distributed sensor networks (DSNs) common in many natural and engineering applications. From among the possible network structures, we focus on bipartite graph structure as it represents a typical MGML structure and has a wide applicability in the real world. We establish exact conditions for consensus and derive a precise relationship between the consensus value and the degree distribution of nodes in a bipartite MGML DSN. We also demonstrate that for subclasses of connectivity patterns, convergence time and simple characteristics of network topology can be captured by explicit algebra. Direct inference of the convergence behavior of consensus strategies from MGML DSN structure is the main contribution of this paper. The insights gained from our analysis facilitate the design and development of large‐scale DSNs that meet specific performance criteria. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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H-Infinity Static Output-feedback Control for Rotorcraft 总被引:1,自引:0,他引:1
Jyotirmay Gadewadikar Frank L. Lewis Kamesh Subbarao Kemao Peng Ben M. Chen 《Journal of Intelligent and Robotic Systems》2009,54(4):629-646
The problem of stabilization of an autonomous rotorcraft platform in a hover configuration subject to external disturbances
is addressed. Necessary and sufficient conditions are presented for static output-feedback control of linear time-invariant
systems using the H-Infinity approach. Simplified conditions are given which only require the solution of two coupled matrix
design equations. This paper also proposes a numerically efficient solution algorithm for the coupled design equations to
determine the output-feedback gain. A major contribution is that an initial stabilizing gain is not needed. The efficacy of
the control law and the disturbance accommodation properties are shown on a rotorcraft design example. The helicopter dynamics
do not decouple as in the fixed-wing aircraft case, so that the design of helicopter flight controllers with a desirable intuitive
structure is not straightforward. In this paper an output feedback approach is given that allows one to selectively close
prescribed multivariable feedback loops using a reduced set of the states. Shaping filters are added that improve performance
and yield guaranteed robustness and speed of response. This gives direct control over the design procedure and performance.
Accurate identification of the System parameters is a challenging task for rotorcraft control, addition of loop shaping facilitates
implementation engineers to counteract unmodeled high frequency dynamics. The net result yields control structures that have
been historically accepted in the flight control community. 相似文献
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Kamesh MadduriEun-Jin Im Khaled Z. Ibrahim Samuel WilliamsStéphane Ethier Leonid Oliker 《Parallel Computing》2011,37(9):501-520
The next decade of high-performance computing (HPC) systems will see a rapid evolution and divergence of multi- and manycore architectures as power and cooling constraints limit increases in microprocessor clock speeds. Understanding efficient optimization methodologies on diverse multicore designs in the context of demanding numerical methods is one of the greatest challenges faced today by the HPC community. In this work, we examine the efficient multicore optimization of GTC, a petascale gyrokinetic toroidal fusion code for studying plasma microturbulence in tokamak devices. For GTC’s key computational components (charge deposition and particle push), we explore efficient parallelization strategies across a broad range of emerging multicore designs, including the recently-released Intel Nehalem-EX, the AMD Opteron Istanbul, and the highly multithreaded Sun UltraSparc T2+. We also present the first study on tuning gyrokinetic particle-in-cell (PIC) algorithms for graphics processors, using the NVIDIA C2050 (Fermi). Our work discusses several novel optimization approaches for gyrokinetic PIC, including mixed-precision computation, particle binning and decomposition strategies, grid replication, SIMDized atomic floating-point operations, and effective GPU texture memory utilization. Overall, we achieve significant performance improvements of 1.3-4.7× on these complex PIC kernels, despite the inherent challenges of data dependency and locality. Our work also points to several architectural and programming features that could significantly enhance PIC performance and productivity on next-generation architectures. 相似文献
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Mumtaz Ahmad Ashraf Aboulnaga Shivnath Babu Kamesh Munagala 《The VLDB Journal The International Journal on Very Large Data Bases》2011,20(4):589-615
The typical workload in a database system consists of a mix of multiple queries of different types that run concurrently.
Interactions among the different queries in a query mix can have a significant impact on database performance. Hence, optimizing
database performance requires reasoning about query mixes rather than considering queries individually. Current database systems
lack the ability to do such reasoning. We propose a new approach based on planning experiments and statistical modeling to
capture the impact of query interactions. Our approach requires no prior assumptions about the internal workings of the database
system or the nature and cause of query interactions, making it portable across systems. To demonstrate the potential of modeling
and exploiting query interactions, we have developed a novel interaction-aware query scheduler for report-generation workloads.
Our scheduler, called QShuffler, uses two query scheduling algorithms that leverage models of query interactions. The first algorithm is optimized for workloads
where queries are submitted in large batches. The second algorithm targets workloads where queries arrive continuously, and
scheduling decisions have to be made online. We report an experimental evaluation of QShuffler using TPC-H workloads running
on IBM DB2. The evaluation shows that QShuffler, by modeling and exploiting query interactions, can consistently outperform
(up to 4x) query schedulers in current database systems. 相似文献