41746629
Quick Buddy-Subcube Compaction in Hypercubes
After repeated subcube allocation and deallocation, the hypercube system tends to become fragmented, which can be taken care of by using subcube compaction. Basic buddy-subcube compaction deals with compacting free buddy-subcubes with the same dimension concurrently. All migration paths are pairwise disjoint and contain no links of active subcubes, so that task migration can be performed without suspending the execution of other jobs. This paper considers quick buddy-subcube compaction in that not only can free subcubes with two adjacent dimensions be compacted concurrently, but two disjoint paths can be established between every pair of source-target nodes. Parallel subcube compaction with two concurrent dimensions apparently speeds up subcube compaction by a factor of two. The use of double disjoint paths between each pair of source-target nodes also speeds up subcube compaction by a factor of nearly two. Thus, our approach can speed up subcube compaction by a factor of nearly four.
19964958
Near-optimal data allocation over multiple broadcast channels
Data broadcast is known as a scalable way to transmit database items to large client populations through a wireless channel. However, with a large set of items, the expected delay of receiving desired data increases due to the sequential nature of the broadcast channel. One possible solution is to increase the number of available channels and allocate items evenly over these channels, then cyclically broadcast data in each channel. In view of data access skew (the access frequencies of data are usually different), some channels may be reserved exclusively for those few frequently requested items, while the infrequently accessed bulk of data are allocated on other channels. In this paper, an O(N log K) restricted dynamic programming (RDP) algorithm is proposed to partition N items over K channels assuming data access is skewed with the object of minimizing the average expected delay (aed) of clients. To speed up the DP process, for any partition, we predict a possible location which may be very close to the optimal cut by using a low bound as the actual aed for the remaining items. Thus, the number of comparisons in DP can be restricted to a small interval around the predicted cut point. To further reduce the costs in DP, the hierarchical property of optimal solution is adopted. Simulation results show that, the hit rate obtained by RDP is higher than 90% and it also outperforms the existing algorithm 200%. We extend the work of RDP and develop an O(N log N log K) PKR algorithm; simulation results show that the solution is optimal.
12433317
Characterization of 1/f noise vs. number of gate stripes in MOS transistors
This paper examines low-frequency 1/f noise (or Bicker noise) in metal oxide semiconductor field-effect transistors (MOSFETs) versus number of gate stripes and bias conditions. Simulations using SPICE/Spectre with Cadence models have displayed the dependence of 1/f noise on the number of gate stripes and the bias conditions. Experimental results from a test chip designed and fabricated in a 0.5 /spl mu/m CMOS process show that 1/f noise is independent of the number of gate stripes in both saturation and linear regions for both P-channel and N-channel devices. The measured results have also shown that 1/f noise is independent of the bias conditions in the saturation region but dependent on the bias conditions in the linear region.
5569010
A Fast Efficient Parallel Hough Transform Algorithm on LARPBS
A parallel algorithm for Hough transform on a linear array with reconfigurable pipeline bus system (LARPBS) is presented. Suppose the number of θ-values to be considered is m, for an image with n × n pixels, the algorithm can complete Hough transform in O(1) time using mn2 processors and achieve optimal speed and efficiency. We also illustrate how to partition data and perform the algorithm on a LARPBS with fewer than mn2 processors, and hence show that the algorithm is highly scalable.
9276534
Setuid Demystified
641995
An Admission Control Scheme for Predictable Server Response Time for Web Accesses
The diversity in web object types and their resource requirements contributes to the unpredictability of web service provisioning. In this paper, an eÆcient admission control algorithm, PACERS, is proposed to provide di erent levels of services based on the server workload characteristics. Service quality is ensured by periodical allocation of system resources based on the estimation of request rate and service requirements of prioritized tasks. Admission of lower priority tasks is restricted during high load periods to prevent denial-of-services to high priority tasks. A doublequeue structure is implemented to reduce the e ects of estimation inaccuracy and to utilize the spare capacity of the server, thus increasing the system throughput. Response delays of the high priority tasks are bounded by the length of the prediction period. Theoretical analysis and experimental study show that the PACERS algorithm provides desirable throughput and bounded response delay to the prioritized tasks, without any signi cant impact on the aggregate throughput of the system under various workload.
196155386
Compound brushing
This paper proposes a conceptual model called compound brushing for modeling the brushing techniques used in dynamic data visualization. In this approach brushing techniques are modeled as higraphs with five types of basic entities: data, selection, device, renderer, and transformation. Using this model, a flexible visual programming tool is designed not only to configure/control various common types of brushing techniques currently used in dynamic data visualization, but also to investigate new brushing techniques.