The gains of parallel query execution can be limited because of high start-up time, interference between execution entities, and poor load balancing. In this paper, we present a solution which reduces these limitations in DBS3, a shared-memory parallel database system. This solution combines static data partitioning and dynamic processor allocation to adapt to the execution context. It makes DB...

An approach for solving sparse triangular systems of equations on highly parallel computers employs a partitioned representation of the inverse of the triangular matrix so that the solution can be obtained by a series of matrix-vector multiplications. This approach requires a number of global communication steps that is proportional to the number of factors in the partitioning. The problem of n...

this study was conducted to evaluatethe effects of different inter- and intra-row spacing on the dry matter accumulation and partitioning coefficients in faba bean, barakat cultivar. experiment was conducted as factorial in a randomized complete block design with three replications. factors were inter-row spacing (15, 30, 45 and 60 cm) and intra-row spacing (5, 10 and 15 cm). the plant dry matt...

We demonstrate the efficiency of the multidomain sampler (MDS) in finding multiple distinct global minima and low-energy local minima in the hydrophobic-polar (HP) lattice protein model. Extending the idea of partitioning energy space in the Wang-Landau algorithm, our approach introduces an additional partitioning scheme to divide the protein conformation space into local basins of attraction. ...

To minimize data movement, state-of-the-art parallel sorting algorithms use sampling and histogramming techniques to partition keys prior to redistribution. Samples enable partitioning to be done using representative subset of the keys, while histogramming enables evaluation and iterative improvement of a given partitioning. We introduce Histogram sort with sampling (HSS), which combines sampli...

We consider the problem of partitioning rectilinear polygons into rectangles, using segments of minimum total length. This problem is NP-hard for polygons with holes. Even for hole-free polygons no known algorithm can nd an optimal partitioning in less than O(n 4) time. We present the rst linear-time algorithm for computing rectangula-tions of hole-free polygons, within a constant factor of the...

Quorum systems are a mechanism for obtaining fault-tolerance and efficient distributed systems. We consider geographic quorum systems; a geographic quorum system is a partitioning of a set X of points in the plane (representing servers) into quorums (i.e. clusters) of size k. The distance between a point p and a cluster C is the Euclidean distance between p and the farthest point in C. We prese...

In this paper, we propose and study a new semi-random model for graph partitioning problems. We believe that it captures many properties of real–world instances. The model is more flexible than the semi-random model of Feige and Kilian and planted random model of Bui, Chaudhuri, Leighton and Sipser. We develop a general framework for solving semi-random instances and apply it to several problem...

Adaptive Block FSAI (ABF) is a novel and promising preconditioner for the efficient parallel solution of linear systems and eigenproblems arising from subsurface applications. However, one of its main drawbacks stems from the reduced scalability, as the iteration count to converge tends to grow increasing the number of processors. Graph partitioning techniques can help improve both the precondi...