Optimal communication algorithms for hypercubes

Cover title.Includes bibliographical references.Supported by NSF with matching funds from Bellcore, Inc. ECS-8519058 ECS-8552419 Supported by the ARO. DAAL03-86-K-0171 Supported by the AFOSR. AFOSR-88-0032by D.P. Bertsekas ... [et al.]

Research of Lightweight Structures for Sandwich Core Model

The objective of this chapter is to focus on finding mechanical properties for two models defined as core-filled model (Type 1) and core-spaced model (Type 2) created by direct metal laser sintering (DMLS). Applied material is aluminum alloy AlSi10Mg powder and each model is created as a vertical additive manufacturing with DMLS. After quasi-static compression, Type 1 showed 19% higher elastic modulus, 12% higher compressive yield strength, and 51.6% higher elongation than Type 2. By uniaxial compressive test, there found two issues that can be the reasons to make weaker models by 3D printing were found: melted metals by DMLS are not connected with each other preciously and a space in additive layer when additive manufacturing makes a shape of specimen. In addition, anisotropy is the significant factor to decide stiffness or strength. In nearby future, various kinds of unit models such as core-filled or core-spaced model hope to be made a sandwich core structure and to be investigating more deeply about bending or shear properties continuously. In the near future, it is hoped that we see more upgraded 3D printing techniques for making aerospace materials

Assessing and Remedying Coverage for a Given Dataset

Data analysis impacts virtually every aspect of our society today. Often, this analysis is performed on an existing dataset, possibly collected through a process that the data scientists had limited control over. The existing data analyzed may not include the complete universe, but it is expected to cover the diversity of items in the universe. Lack of adequate coverage in the dataset can result in undesirable outcomes such as biased decisions and algorithmic racism, as well as creating vulnerabilities such as opening up room for adversarial attacks. In this paper, we assess the coverage of a given dataset over multiple categorical attributes. We first provide efficient techniques for traversing the combinatorial explosion of value combinations to identify any regions of attribute space not adequately covered by the data. Then, we determine the least amount of additional data that must be obtained to resolve this lack of adequate coverage. We confirm the value of our proposal through both theoretical analyses and comprehensive experiments on real data.Comment: in ICDE 201

Multinode broadcast in hypercubes and rings with randomly distributed length of packets

Includes bibliographical references (p. 19-20).Cover title.Research supported by the NSF. NSF-DDM-8903385 Research supported by the ARO. DAAL03-b6-K-0171by Emmanouel A. Varvarigos and Dimitri P. Bertsekas

Partial multinode broadcast and partial exchange algorithms for d-dimensional meshes

Caption title. "Revision of January 1992."Includes bibliographical references (p. 24-26).Supported by NSF. NSF-ECS-8519058 Supported by ARO. DAAL03-86-K-0171by Emmanouel A. Varvarigos and Dimitri P. Bertsekas

Transposition of banded matrices in hypercubes : a "nearly isotropic" task

Includes bibliographical references (p. 19).Supported by NSF. NSF-DDM-8903385 Supported by the ARO. DAAL03-92-G-0115by Emmanouel A. Varvarigos, Dimitri P. Bertsekas

Efficient hypercube communications

Hypercube algorithms may be developed for a variety of communication-intensive tasks such as sending a message from one node to another, broadcasting a message from one node to all others, broadcasting a message from each node to all others, all-to-all personalized communication, one-to-all personalized communication, and exchanging messages between nodes via fixed permutations. All these communication patterns are special cases of many-to-many personalized communication. The problem of many-to-many personalized communication is investigated here. Two routing algorithms for many-to-many personalized communication are presented here. The algorithms proposed yield very high performance with respect to the number of time steps and packet transmissions. The first algorithm yields high performance through attempts to equibalance the number of messages at intermediate nodes. This technique tries to avoid creating a bottleneck at any node and thus reduces the total communication time. The second algorithm yields high performance through one-step time-lookahead equibalancing. It chooses from the candidate intermediate nodes the one which will probably have the minimum number of messages in the next cycle

Communication algorithms for isotropic tasks in hypercubes and wraparound meshes

Cover title.Includes bibliographical references (p. 29-30).Research supported by the NSF. NSF-ECS-8519058 Research supported by the ARO. DAAL03-86-K-0171by Emmanouel A. Varvarigos and Dimitri P. Bertsekas

Using offline routing to implement a low latenc 3D FFT in a multinode FPGA system

Thesis (M.S.)--Boston UniversityApplications that require highly parallel computing along with low latency communication due to strong scaling, such as a calculating a 3D FFT for Molecular Dynamics simulations, can be problematic for traditional high performance computing (HPC) clusters. A multinode FPGA array is a good solution for these types of problems due to the direct high speed connections and flexible internal fabric inherent in FPGAs. Offline routing uses precomputed routing information to direct packets and can avoid much of the switching and congestion communication overhead. Two architectures are explored here which show the feasibility ofusing offline routing techniques to reduce communication latencies in FPGA systems. The first architecture targets a single FPGA that was built for initial exploration and to show how the powerful and flexible a single FPGA can be. It attained a maximum clock frequency of 102MHz and latencies of 64us and 250us for 3D FFT calculations of 32^3 and 64^3 data points respectively. The second architecture targets an FPGA that is intended to be the model for each node in the array. The best multinode version is based on a multilevel switching architecture. It has a maximum clock frequency of 134MHz. When scaled to a cluster, latencies project to 2.4us and 5.5us for 3D FFT calculations of 32^3 and 64^3 data points respectively. The two designs show the potential for using a single FPGA and multi-FPGA arrays for HPC applications where communication latency is critical to the application