9232977
Placement constraints in floorplan design
In floorplan design, it is common that a designer will want to control the positions of some modules in the final packing for various purposes like datapath alignment and I/O connection. There are several previous works focusing on some particular kinds of placement constraints. In this paper, we will present a unified method to handle all of them simultaneously, including preplace constraint, range constraint, boundary constraint, alignment, abutment, and clustering, etc., in general, nonslicing floorplans. We have used incremental updates and an interesting idea of reduced graph to improve the runtime of the method. We tested our method using some benchmark data with about 1/8 of the modules having placement constraints and the results are very promising. Good packings with all the constraints satisfied can be obtained efficiently.
12807811
A matrix synthesis approach to thermal placement
In this paper, we consider the thermal placement problem for gate arrays. We introduce a new combinatorial opti- mization problem, matrix synthesis problem (MSP), to model the thermal placement problem. Given a list of nonnegative real numbers and an integer , MSP constructs a matrix out of the given numbers such that the maximum sum among all submatrices is minimized. We show that MSP is NP-complete and present several provably good approximation algorithms for the problem. We also demonstrate that our thermal placement strategy is flexible enough to allow simultaneous consideration of other objectives such as wiring.
34361185
Dilation-5 embedding of 3-dimensional grids into hypercubes
We present an algorithm to map the nodes of a 3-dimensional grid to the nodes of its optimal hypercube on a one-to-one basis with dilation at most 5.<<ETX>>
12805154
Efficient rectilinear Steiner tree construction with rectilinear blockages
Given n points on a plane, a rectilinear Steiner minimal tree (RSMT) connects these points through some extra points called Steiner points to achieve a tree with minimal total wire length. Taking blockages into account dramatically increases the problem complexity. It is extremely unlikely that an efficient optimal algorithm exists for rectilinear Steiner minimal tree construction with rectilinear blockages (RSMTRB). Although there exist some heuristic algorithms for this problem, they have either poor quality or expensive running time. In this paper, we propose an efficient and effective approach to solve RSMTRB. The connection graph we used in this approach is called spanning graph which only contains O(n) edges and vertices. An O(n log n) time algorithm is proposed to construct spanning graph for RSMTRB. The experimental results show that this approach can achieve a solution with significantly reduced wire length. The total run time increased is negligible in the whole design flow.
53246587
A revisit to floorplan optimization by Lagrangian relaxation
52810492
Optimal cell flipping in placement and floorplanning
In a placed circuit, there are a lot of movable cells that can be flipped to further reduce the total wirelength, without affecting the original placement solution. We aim at solving this flipping problem optimally. However, solving such a problem optimally is non-trivial given the gigantic sizes of modern circuits. We are able to identify a large portion of cells (about 75%) of which the orientation (flipped or not flipped) can be determined independent of the orientations of all the other cells. We have derived three non-trivial conditions to identify those so called independent cells, strictly solvable cells and conditionally solvable cells. In this way, we can greatly reduce the number of cells whose orientations are dependent on each other. Finally, the cell flipping problem of the remaining dependent cells can be formulated as a mixed integer linear programming (MILP) problem and solved optimally. However, this may still be too slow for extremely large circuits and we have applied two other methods, linear programming (LP) and linear programming followed by mixed integer linear programming (LP+MILP) to solve the problem. Experimental results show that by identifying those independent and solvable cells first and applying the LP+MILP technique, we can solve this flipping problem effectively and obtain results just 0.01% more than the optimal. In addition, we can improve the wirelength and number of overflow tiles by 5% and 9% respectively on the floorplanning benchmarks
37782928
A multi-dimensional version of the I test
Abstract Two-dimensional arrays with linear subscripts occur quite frequently in real programs. In general, for multi-dimensional linear arrays under constant bounds the Lambda test is an efficient data dependence method to check whether there exist real solutions. In this paper, we propose a multi-dimensional version of the I test, the multi-dimensional I test, that can be applied to testing whether there are integer solutions for multi-dimensional linear arrays under constant limits. Experiments with benchmark showing the effects of the multi-dimensional I test on testing precision and testing efficiency are also presented.
17686405
A time-series biclustering algorithm for revealing co-regulated genes
Although existing bicluster algorithms claimed to be able to discover co-regulated genes under a subset of given experiment conditions, they ignore the inherent sequential relationship between crucial time points and thus are not applicable to analyze time-series gene expression data. A simple and effective deletion-based algorithm, using the mean squared residue score as a measure, was developed to bicluster time-series gene expression data. While enforcing a threshold value for the score, the algorithm alternately eliminates genes and time points according to their correlation to the bicluster. To ensure the time locality, only the starting and ending points in the time interval are eligible for deletion. As a result, the number of genes and the length of time interval are simultaneously maximized. Our experimental results shown that the proposed method is capable of identifying co-regulated genes characterized by partial time-course data that previous methods failed to discover.
7900750
A Web-service oriented framework for building SCORM compatible learning management systems
Managing the large amount of learning content involved in the development of an expandable learning management system (LMS) is a critical task for most educational organizations. In designing such a system, consideration must be given not only to the requirement of instructors and students, but also to the adaptive qualities of the system itself, because of the rapidly changing software environment. Unlike most enterprises, educational organization can't afford high system maintenance. Development of a flexible, expandable and reliable learning management system is, therefore, imperative. This paper proposes a Web service oriented framework in building a sharable content object reference model (SCORM) compatible LMS. We integrated the SCORM concept with distributed computing technologies to build the components of the LMS and demonstrate how these services can be configured to create a complete system. This framework increases reusability and reduces the maintenance requirements of the LMS. It provides a way for small educational organizations, with limited resources, to build a complete SCORM compatible LMS. In such an ideal situation, the content provider not only provides the content, but also the service for the consumers of that content.
41515379
The I+ Test
The I test is an efficient and precise data dependence method to ascertain whether integer solutions exist for one-dimensional arrays with constant bounds. For one-dimensional arrays with variable limits, the I test assumes that there may exist integer solutions. In this paper, we propose the I+ test|an extended version of the I test. The I+ test can be applied towards determining whether integer solutions exist for onedimensional arrays with either variable or constant limits, improving the applicable range of the I test. Experiments with benchmark cited from EISPACK, LINPACK, Parallel loops, Livermore loops and Vector loops showed that among 1189 pairs of one-dimensional arrays tested, 183 had their data dependence analysis amended by the I+ test. That is, the I+ test increases the success rate of the I test by approximately 15:4 percent. Comparing with the Power test and the Omega test, the I+ test has higher accuracy than the Power test and shares the same accuracy with the Omega test when determining integer solutions for these 1189 pairs of one-dimensional arrays, but has much better efficiency over them.
8131087
Multipath-Based Multicasting Strategies for Wormhole-Routed Star Graph Interconnection Networks
The star graph interconnection network has been recognized as an attractive alternative to the popular hypercube network. In this paper, we present a multipath-based multicast routing model for wormholerouted star graph networks, propose two efficient multipath routing schemes, and contrast the performance of the proposed schemes with the performance of the scheme presented in our previous work. Both of the two proposed schemes have been proven to be deadlock-free. The first scheme, simplemultipath routing, uses multiple independent paths for concurrent multicasting. The second scheme, two-phase multipath routing, includes two phases: source-to-relay and relay-to-destination. For each phase, multicasting is carried out using simple multipath routing. Experimental results show that, for short and medium messages with small message startup latencies, the proposed schemes reduce multicast latency more efficiently than other schemes.