Parallel and Distributed Computing

The 14 chapters presented in this book cover a wide variety of representative works ranging from hardware design to application development. Particularly, the topics that are addressed are programmable and reconfigurable devices and systems, dependability of GPUs (General Purpose Units), network topologies, cache coherence protocols, resource allocation, scheduling algorithms, peertopeer networks, largescale network simulation, and parallel routines and algorithms. In this way, the articles included in this book constitute an excellent reference for engineers and researchers who have particular interests in each of these topics in parallel and distributed computing

Dynamic Dependability Analysis using HOL Theorem Proving with Application in Multiprocessor Systems

Dynamic dependability analysis has become an essential step in the design process of safety-critical systems to ensure the delivery of a trusted service without failures. Dependability usually encompasses several attributes, such as reliability and availability. A dynamic dependability model is created using one of the dependability modeling techniques, such as Dynamic Fault Trees (DFTs) and Dynamic Reliability Block Diagrams (DRBDs). Several analysis methods, including paper-and-pencil or simulation, exist for analyzing these models to ascertain various dependability related parameters. However, their results cannot be always trusted since they may involve some approximations, truncations or even errors. Formal methods, such as model checking and theorem proving, can be used to overcome these inaccuracy limitations due to their inherent soundness and completeness. However, model checking suffers from state-space explosion if the state space is large. While, theorem proving was used only for the static dependability analysis without considering the system dynamics. In order to conduct the formal dependability analysis of systems that exhibit dynamic failure behaviors within a theorem prover, these models need to be captured formally, where their structures, operators and properties are properly formalized. In this thesis, we provide a complete framework for the formal dependability analysis of systems modeled as DFTs and DRBDs in the HOL4 higher-order logic theorem prover. We provide the formalization of DFT gates and verify important simplification theorems based on well-known DFT algebra. In addition, our framework allows both qualitative and quantitative DFT analyses to be conducted using theorem proving. We use this formalization to formally verify the DFT rewrite rules, that are used by automated DFT analysis tools, to ascertain their correctness. Due to the lack of a DRBD algebra that allows the analysis using a theorem prover, in this thesis, we develop and formalize a novel algebra that includes operators and simplification theorems to formalize traditional RBD structures, such as the series and parallel, besides the DRBD spare construct. We formally verify their reliability expressions, which allows conducting both the qualitative and quantitative analyses of a given system. Leveraging upon the complementary nature of DFTs and DRBDs, our proposed framework provides the possibility of formally converting one model to the other, which allows reasoning about both the success and failure of a given system. Our framework provides generic expressions of probability of failure and reliability that are independent of the failure distribution of an arbitrary number of system components, which cannot be obtained using other formal tools, such as model checking. In order to demonstrate the usefulness of the proposed framework, we formally model and analyze the dependability of the terminal, broadcast and network reliability of shuffle-exchange networks, which are multistage interconnections networks that are used to connect the elements of multiprocessor systems. Conducting a sound analysis with generic expressions is essential in these systems, where it is required to accurately capture and analyze the failure behavior

Three Highly Parallel Computer Architectures and Their Suitability for Three Representative Artificial Intelligence Problems

Virtually all current Artificial Intelligence (AI) applications are designed to run on sequential (von Neumann) computer architectures. As a result, current systems do not scale up. As knowledge is added to these systems, a point is reached where their performance quickly degrades. The performance of a von Neumann machine is limited by the bandwidth between memory and processor (the von Neumann bottleneck). The bottleneck is avoided by distributing the processing power across the memory of the computer. In this scheme the memory becomes the processor (a smart memory ). This paper highlights the relationship between three representative AI application domains, namely knowledge representation, rule-based expert systems, and vision, and their parallel hardware realizations. Three machines, covering a wide range of fundamental properties of parallel processors, namely module granularity, concurrency control, and communication geometry, are reviewed: the Connection Machine (a fine-grained SIMD hypercube), DADO (a medium-grained MIMD/SIMD/MSIMD tree-machine), and the Butterfly (a coarse-grained MIMD Butterflyswitch machine)

Upper Bound Analysis and Routing in Optical Benes Networks

Multistage Interconnection Networks (MIN) are popular in switching and communication applications. It has been used in telecommunication and parallel computing systems for many years. The new challenge facing optical MIN is crosstalk, which is caused by coupling two signals within a switching element. Crosstalk is not too big an issue in the Electrical Domain, but due to the stringent Bit Error Rate (BER) constraint, it is a big major concern in the Optical Domain. In this research dissertation, we will study the blocking probability in the optical network and we will study the deterministic conditions for strictly non-blocking Vertical Stacked Optical Benes Networks (VSOBN) with and without worst-case scenarios. We will establish the upper bound on blocking probability of Vertical Stacked Optical Benes Networks with respect to the number of planes used when the non-blocking requirement is not met. We will then study routing in WDM Benes networks and propose a new routing algorithm so that the number of wavelengths can be reduced. Since routing in WDM optical network is an NP-hard problem, many heuristic algorithms are designed by many researchers to perform this routing. We will also develop a genetic algorithm, simulated annealing algorithm and ant colony technique and apply these AI algorithms to route the connections in WDM Benes network

Efficient parallel computation on multiprocessors with optical interconnection networks

This dissertation studies optical interconnection networks, their architecture, address schemes, and computation and communication capabilities. We focus on a simple but powerful optical interconnection network model - the Linear Array with Reconfigurable pipelined Bus System (LARPBS). We extend the LARPBS model to a simplified higher dimensional LAPRBS and provide a set of basic computation operations. We then study the following two groups of parallel computation problems on both one dimensional LARPBS\u27s as well as multi-dimensional LARPBS\u27s: parallel comparison problems, including sorting, merging, and selection; Boolean matrix multiplication, transitive closure and their applications to connected component problems. We implement an optimal sorting algorithm on an n-processor LARPBS. With this optimal sorting algorithm at disposal, we study the sorting problem for higher dimensional LARPBS\u27s and obtain the following results: • An optimal basic Columnsort algorithm on a 2D LARPBS. • Two optimal two-way merge sort algorithms on a 2D LARPBS. • An optimal multi-way merge sorting algorithm on a 2D LARPBS. • An optimal generalized column sort algorithm on a 2D LARPBS. • An optimal generalized column sort algorithm on a 3D LARPBS. • An optimal 5-phase sorting algorithm on a 3D LARPBS. Results for selection problems are as follows: • A constant time maximum-finding algorithm on an LARPBS. • An optimal maximum-finding algorithm on an LARPBS. • An O((log log n)2) time parallel selection algorithm on an LARPBS. • An O(k(log log n)2) time parallel multi-selection algorithm on an LARPBS. While studying the computation and communication properties of the LARPBS model, we find Boolean matrix multiplication and its applications to the graph are another set of problem that can be solved efficiently on the LARPBS. Following is a list of results we have obtained in this area. • A constant time Boolean matrix multiplication algorithm. • An O(log n)-time transitive closure algorithm. • An O(log n)-time connected components algorithm. • An O(log n)-time strongly connected components algorithm. The results provided in this dissertation show the strong computation and communication power of optical interconnection networks

Parallel computation on sparse networks of processors

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A review on economic and technical operation of active distribution systems

© 2019 Elsevier Ltd Along with the advent of restructuring in power systems, considerable integration of renewable energy resources has motivated the transition of traditional distribution networks (DNs) toward new active ones. In the meanwhile, rapid technology advances have provided great potentials for future bulk utilization of generation units as well as the energy storage (ES) systems in the distribution section. This paper aims to present a comprehensive review of recent advancements in the operation of active distribution systems (ADSs) from the viewpoint of operational time-hierarchy. To be more specific, this time-hierarchy consists of two stages, and at the first stage of this time-hierarchy, four major economic factors, by which the operation of traditional passive DNs is evolved to new active DNs, are described. Then the second stage of the time-hierarchy refers to technical management and power quality correction of ADSs in terms of static, dynamic and transient periods. In the end, some required modeling and control developments for the optimal operation of ADSs are discussed. As opposed to previous review papers, potential applications of devices in the ADS are investigated considering their operational time-intervals. Since some of the compensating devices, storage units and generating sources may have different applications regarding the time scale of their utilization, this paper considers real scenario system operations in which components of the network are firstly scheduled for the specified period ahead; then their deviations of operating status from reference points are modified during three time-intervals covering static, dynamic and transient periods