In this paper, we present an efficient method for the fault simulation of the reconvergent fan-out stem. Our method minimizes the fault propagating region by analyzing the topology of the circuit, whose region is smaller than that of Tulip's. The efficiency of our method is illustrated by experimental results for a set of benchmark circuits.

A processor allocation scheme for mesh computers greatly affects their system utilization. The performance of an allocation scheme is largely dependent on its ability to detect available submeshes. We propose a new type of submesh, called a link-disjoint submesh, for processor allocation in mesh computers. This type of submesh increases the submesh recognition capability of an allocation scheme. A link-disjoint submesh is not a contiguous submesh as in the previous scheme, but this submesh still has no common communication link with any other submesh. When wormhole routing or circuit switching is used, the communication delay caused by non-contiguous processor allocation is minor. Through simulation, the performance of our scheme is measured and compared to the previous schemes in terms of such parameters as finish time and system utilization. It is shown through simulation that the link-disjoint submesh increases the performance of an allocation scheme.

PID-type controllers have been well-known and widely used in many industries. Their regulation property of those was more improved through the addition of Bang-Bang-action. In spite of the potentials of these PID-plus Bang-Bang controllers, their regulation property is still limited by the fixed window limit value that determines the control action, i. e., PID or Bang-Bang. Thus, this paper presents an approach for improving the regulation property by dynamically changing the window limit value according to the plant dynamics with Neural Network predictive model. The improved regulation property is illustrated through simulation studies for position control of DC servo-motor system in the sense of classical figures of merit such as overshoot and rise time.

A Hierarchical Cubic Network (HCN) is a hierarchical hypercube network proposed by Ghose. The HCN is topologically superior to many other similar networks, in particular, the hypercube. It has a considerably lower diameter than a comparable hypercube and is realized using almost half the number of links per node as a comparable hypercube. In this paper, we propose the shortest routing algorithm in HCN(n, n) and show that the diameter of HCN(n, n) with 22n nodes is n(n1)/31 which is about 2/3 of that of a comparable hypercube. We also propose the optimal routing algorithm in HCN(m, n) where mn and obtain that its diameter is n(m1)/31. Typical parallel algorithms run in HCN(m, n) with the same time complexity as a hypercube and the hypercube topology can be emulated with O(1) time complexity in it.

In static multiprocessor scheduling, heuristic algorithms have been widely used. Instead of gaining execution speed, most of them show non promising solutions since they search only a part of solution spaces. In this paper, we propose a scheduling algorithm using the genetic algorithm (GA) which is a well-known stochastic search algorithm. The proposed algorithm, named ordered-deme GA (OGA), is based on the multiple subpopulation GA, where a global population is divided into several subpopulations (demes) and each demes evolves independently. To find better schedules, the OGA orders demes from the highest to the lowest deme and migrates both the best and the worst individuals at the same time. In addition, the OGA adaptively assigns different mutation probabilities to each deme to improve search capability. We compare the OGA with well-known heuristic algorithms and other GAs for random task graphs and the task graphs from real numerical problems. The results indicate that the OGA finds mostly better schedules than others although being slower in terms of execution time.

A method to reduce the bandwidth between texture memory and the rasterization processor is proposed. It achieves the reduction by not fetching useless texels from texture memory in bilinear filtering. Since it does not depend on cache and loss compression, it can be used in applications where the reusability of texels is low and loss compression is prevented.

We present a scalable parallel rasterizer based on our interleaved scanline rasterization. The sorting overhead of a conventional scanline-based parallel rendering approach has been studied and removed by implementing a scanline assignment hardware. All advantages of the scanline-based parallel rendering are kept such that a good scalability and a small memory usage are achieved. Our architecture is evaluated precisely by a discrete event-based simulation, and the rendering performance and utilization are shown for a various number of rasterizers. The simulation results show more than 8 Mtriangles/s of performance with 64 rasterization engines running at 10 MHz.

A simple method is presented to calculate the parasitic capacitance effect in the propagation delay of series-connected MOS (SCM) structures. This method divides SCM circuits into two parts and accurately calculates the contribution of each part to the difference from the delay without parasitic capacitances.

We propose a simplified model of real-time joint source-channel coding, which can be used to adaptively determine the quality-optimal code rate of forward error correction (FEC) coding. The objective is to obtain the maximum video quality in the receiver, while taking time-varying packet loss into consideration. To this end, we propose a simplified model of the threshold set of the residual video packet loss rate (RVPLR). The RVPLR is the rate of residual loss of video packets after channel decoding. The threshold set is defined as a set of discrete RVPLRs in which the FEC code rate must be changed in order to maintain minimum distortion during increases or decreases of channel packet loss. Because the closed form of the proposed model is very simple and has one scene-dependent model parameter, a video sender can be easily implemented with the model. To train the scene-dependent model parameters in real-time, we propose a test-run method. This method accelerates the test-run while remaining sufficiently accurate for training the scene-dependent model parameters. By using the proposed model and test-run, the video sender can always find the optimal code rate on the fly whenever there is a change in the packet loss status in the channel. An experiment shows that the proposed model and test-run can efficiently determine the near-optimal code rate in joint source-channel coding.

Footprint assembly was proposed to reduce the blurriness of texture mapped image by mipmapping. Even though it can improve the quality of texture mapped image, there are yet blurring due to the limitation of it's filter kernel. This paper proposes a novel texture filtering, called adaptive footprint assembly (AFA), to overcome the limitation of footprint assembly. The proposed method greatly improves the quality of texture mapped images.

This letter presents a method for reducing power dissipation in a protocol converter. The communication protocol of a VLSI chip hierarchically consists of several sub-protocols and only one of them can be actively working at any given time. In general, protocol converters are implemented by dual protocols of the initially given protocols which are to be interfaced. If the duals of those sub-protocols are implemented in separate modules, we can separate active modules and inactive modules on the fly since only one of the modules can be active at a time. The active/inactive state of a module can be monitored by the control signals that represent the execution of the protocol corresponding to the module. Power reduction can be achieved by dynamically suppressing the clock supply to inactive modules. To trade-off the power reduction rate against the area overhead, the module granularity must be properly chosen. For this purpose, we implement the duals of the atomic protocols in the same module if their state graphs share states except the initial state. Our experimental results show that this method provides significant savings in power consumption of between 18.4% and 92.1% with a 5.3% area overhead.

Applications usually have their own phases in heap memory usage. The traditional garbage collector fails to match various application phases because the same heuristic on the object behavior is used throughout the entire execution. This paper introduces a phase-adaptive garbage collector which reorganizes the heap layout and adjusts the invocation time of the garbage collection according to the phases. The proposed collector identifies phases by detecting the application methods strongly related to the phase boundaries. The experimental results show that the proposed phase-adaptive collector successfully recognizes application phases and improves the garbage collection time by as much as 41%.

In a conventional file system, the directory tree is traversed to find the inode number of a file. The inode lookup performance degrades as the size of the directory tree increases. In this letter, a new directory scheme, called direct hashing directory, is proposed. The inode number of a file is the cyclic redundancy code of the file's absolute path name such that the inode number can be computed directly. The average number of disk accesses for inode lookup is 1.08, which is order of magnitude faster than the conventional directory schemes such as hashing, B tree, and sequential directory.

This paper addresses a method for constructing surface representation of 3D structures from a sequence of cross-sectional images. Firstly, we propose cell-boundary representation, which is a generalization of PVP method proposed by Yun and Park, and develop an efficient surface construction algorithm from a cell-boundary. Cell-boundary consists of a set of boundary cells with their 1-voxel configurations, and can compactly describe binary volumetric data. Secondly, to produce external surface from the cell-boundary representation, we define 19 modeling primitives (MP) including volumetric, planar and linear groups. Surface polygons are created from those modeling primitives using a simple table look-up operation. Since a cell-boundary can be obtained using only topological information of neighboring voxels, there is no ambiguity in determining modeling primitives which may arise in PVP method. Since our algorithm has data locality and is very simple to implement, it is very appropriate for parallel processing.

In this paper, we define an attributed random graph, which can be considered as a generalization of conventional ones, to include multiple attributes as well as numeric attribute instead of a single nominal attribute in random vertices and edges. Then we derive the probability equations for an attributed graph to be an outcome graph of the attributed random graph, and the equations for the entropy calculation of the attributed random graph. Finally, we propose the application areas to computer vision and machine learning using these concepts.

Joint source-channel coding (JSCC) is a method to jointly allocate the given total transmission bitrate to the source coding and channel coding to maximize the video quality at the receiving end. In this paper, we propose a practical model for efficiently determining a near-optimal code rate for JSCC in real-time video communications. The conventional code rate decision schemes using analytical source coding distortion model and channel-induced distortion model are usually complex, and typically employ the process of model parameter training which involves potentially high computational complexity and implementation cost. To avoid the complex modeling procedure, we introduce a very simple video quality model based on the playable bitrate which is defined as the total bit amount per unit time that is not affected by the channel loss during transmission including correctly recovered bits by the channel decoder. Because the video quality at the receiving end is clearly commensurate with the playable bitrate, we can easily determine the quality-oriented near-optimal code rate by finding the code rate that maximizes the playable bitrate at the sender side. The proposed playable bitrate model is very simple because it does not require the complex training procedure for obtaining model parameters, which is usually required in the conventional code rate decision method. It is shown by simulations that the proposed code rate decision scheme based on the playable bitrate model can efficiently determine the near-optimal code rate for JSCC in terms of high accuracy on the optimal code rate.

A method of range image segmentation using four Markov random field(MRF)s is described in this paper. MRFs are used in depth smoothing, gradient smoothing, edge detection and surface type labeling stage. First, range and its gradient images are smoothed preserving jump and roof edges respectively using line process concept one after another. Then jump and roof edges are extracted, combined and refined using penalizing undesirable edge patterns. Finally, curvatures are computed and the surface types are labeled according to the signs of principal curvatures. The surface type labels are refined using winner-takes-all layers in the stage. The final output is a set of regions with its exact surface type. The energy function is used in order to represent constraints of each stage and the minimum energy state is found using iterative method. Several experimental results show the generality of our approach and the execution speed of the proposed method is faster than that of a typical region merging method. This promises practical applications of our method.

This paper proposes a multi-host RAID-5 architecture in which multiple hosts can access disk array via storage area network. In this configuration, parity inconsistency occurs when different hosts try to write to the same stripe simultaneously. Parity consistency can be ensured by the serialization of the writes to the same stripe with locking method. While conventional locking methods can be used, the performance is degraded in the case of large number of hosts. When multiple-reader single-writer file consistency semantic is used, most of the stripes are written exclusively by a single host, so parity inconsistency problem does not occur. By removing locking of those stripes which amounts to 95% in practical workloads, the performance becomes more scalable and 50% faster than using the conventional stripe locking methods.