Effect of target material on the laser induced pressure pulse measurements for thick P(VDF-TrFE) copolymers

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A comparison study on algorithms for incremental update of frequent sequences

The problem of mining frequent sequences is to extract frequently occurring subsequences in a sequence database. Algorithms on this mining problem include GSP, MFS, and SPADE. The problem of incremental update of frequent sequences is to keep track of the set of frequent sequences as the underlying database changes. Previous studies have extended the traditional algorithms to efficiently solve the update problem. These incremental algorithms include ISM, GSP+ and MFS+. Each incremental algorithm has its own characteristics and they have been studied and evaluated separately under different scenarios. This paper presents a comprehensive study on the relative performance of the incremental algorithms as well as their non-incremental counterparts. Our goal is to provide guidelines on the choice of an algorithm for solving the incremental update problem given the various characteristics of a sequence database. © 2002 IEEE.published_or_final_versio

GPU-TLS: an efficient runtime for speculative loop parallelization on GPUs

Recently GPUs have risen as one important parallel platform for general purpose applications, both in HPC and cloud environments. Due to the special execution model, developing programs for GPUs is difficult even with the recent introduction of high-level languages like CUDA and OpenCL. To ease the programming efforts, some research has proposed automatically generating parallel GPU codes by complex compile-time techniques. However, this approach can only parallelize loops 100% free of inter-iteration dependencies (i.e., DOALL loops). To exploit runtime parallelism, which cannot be proven by static analysis, in this work, we propose GPU-TLS, a runtime system to speculatively parallelize possibly-parallel loops in sequential programs on GPUs. GPU-TLS parallelizes a possibly-parallel loop by chopping it into smaller sub-loops, each of which is executed in parallel by a GPU kernel, speculating that no inter-iteration dependencies exist. After dependency checking, the buffered writes of iterations without mis-speculations are copied to the master memory while iterations encountering mis-speculations are re-executed. GPU-TLS addresses several key problems of speculative loop parallelization on GPUs: (1) The larger mis-speculation rate caused by larger number of threads is reduced by three approaches: the loop chopping parallelization approach, the deferred memory update scheme and intra-warp value forwarding method. (2) The larger overhead of dependency checking is reduced by a hybrid scheme: eager intra-warp dependency checking combined with lazy inter-warp dependency checking. (3) The bottleneck of serial commit is alleviated by a parallel commit scheme, which allows different iterations to enter the commit phase out of order but still guarantees sequential semantics. Extensive evaluations using both microbenchmarks and reallife applications on two recent NVIDIA GPU cards show that speculative loop parallelization using GPU-TLS can achieve speedups ranging from 5 to 160 for sequential programs with possibly-parallel loops. © 2013 IEEE.published_or_final_versio

Adaptive live VM migration over a WAN: modeling and implementation

Recent advances in virtualization technology enable high mobility of virtual machines and resource provisioning at the data-center level. To streamline the migration process, various migration strategies have been proposed for VM live migration over a local-area network (LAN). The most common solution uses memory pre-copying and assumes the storage is shared on the LAN. While applied to a wide-area network (WAN), the VM live migration algorithms need a new design philosophy to address the challenges of long latency, limited bandwidth, unstable network conditions and the movement of storage. This paper proposes a three-phase fractional hybrid pre-copy and post-copy solution for both memory and storage to achieve highly adaptive migration over a WAN. In this hybrid solution, we selectively migrate an important fraction of memory and storage in the pre-copy and freeze-and-copy phase, while the rest (non-critical data set) is migrated during post-copying. We propose a new metric called performance restoration agility, which considers both the downtime and the VM speed degradation during the post-copy phase, to evaluate the migration process. We also develop a profiling framework and a novel probabilistic prediction model to adaptively find a predictably optimal combination of the memory and storage fractions to migrate. This model-based hybrid solution is implemented on Xen and evaluated in an emulated WAN environment. Experimental results show that our solution wins over all others in adaptiveness for various applications over a WAN, while retaining the responsiveness of post-copy algorithms.published_or_final_versio

Probabilistic best-fit multi-dimensional range query in Self-Organizing Cloud

With virtual machine (VM) technology being increasingly mature, computing resources in modern Cloud systems can be partitioned in fine granularity and allocated on demand with 'pay-as-you-go' model. In this work, we study the resource query and allocation problems in a Self- Organizing Cloud (SOC), where host machines are connected by a peer-to-peer (P2P) overlay network on the Internet. To run a user task in SOC, the requester needs to perform a multi-dimensional range search over the P2P network for locating host machines that satisfy its minimal demand on each type of resources. The multi-dimensional range search problem is known to be challenging as contentions along multiple dimensions could happen in the presence of the uncoordinated analogous queries. Moreover, low resource matching rate may happen while restricting query delay and network traffic. We design a novel resource discovery protocol, namely Proactive Index Diffusion CAN (PID-CAN), which can proactively diffuse resource indexes over the nodes and randomly route query messages among them. Such a protocol is especially suitable for the range query that needs to maximize its best-fit resource shares under possible competition along multiple resource dimensions. Via simulation, we show that PID-CAN could keep stable and optimized searching performance with low query delay and traffic overhead, for various test cases under different distributions of query ranges and competition degrees. It also performs satisfactorily in dynamic node-churning situation. © 2011 IEEE.published_or_final_versionThe 40th International Conference on Parallel Processing (ICPP-2011), Taipei City, Taiwan, 13-16 September 2011. In Proceedings of the 40th ICPP, 2011, p. 763-77

Spontaneous depolarization current in different mole ratio VDF/TrFE ferroelectric copolymers

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Structure of nanocrystalline powder and thin films of lead lanthanum titanate prepared by the sol-gel process

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Thermally stimulated depolarization current of BaTiO₃/P[VDF(70)-TrFE(30)] 0-3 ferroelectric composites

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Effects of site substitutions and concentration on upconversion luminescence of Er³⁺-doped perovskite titanate

Author name used in this publication: Jianhua Hao2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Raman spectra and structural phase transition in nanocrystalline lead lanthanum titanate

Author name used in this publication: Q. F. ZhouAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: Q. Q. ZhangAuthor name used in this publication: C. L. Choy2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe