Hiroyuki OCHI Tatsuya SUZUKI Sayaka MATSUNAGA Yoichi KAWANO Takao TSUDA
Floating-point units (FPUs) are indispensable in processors, 3D-graphic engines, etc. To improve design productivity of these LSIs, FPU IPs are strongly desired. However, it is impossible to cover wide range of needs by an FPU IP, because there are various kind of options in specifications (e.g., operating frequency, latency, and ability of pipeline operation) and implementations (e.g., hardware algorithms). Thus, multiple IPs are needed even for the same functionality. In this paper, we propose to build an IP Library which consists of large number of FPU IPs with various kind of specifications and implementations, and which has catalogue data that shows not only specifications but also post-layout area and power dissipation of each IP. As the first step of the project, we have developed an IP Library targeted to Rohm 0.35 µm triple-metal process, which consists of 20 IPs for IEEE-754-standard single-precision floating-point division with 5 operating frequencies (50 MHz, 75 MHz, 100 MHz, 125 MHz, and 150 MHz), with two options whether pipelined or not, and with two hardware algorithms (the restoring method and the SRT method). We have also developed a catalogue for the IP Library, which shows post-layout area and power dissipation as well as specification of each IP. We have introduced two metrics "performance-area ratio (MFLOPS/mm2)" and "performance-power ratio (MFLOPS/W)" to afford a good insight into efficiency of implementations. From the catalogue data, the restoring method is, on the average, 1.4 times and 2.3 times better than the SRT method in terms of performance-area ratio and performance-power ratio, respectively. The developed catalogue is usable not only for selection of the optimal IP for a specific application, but also for quantitative analysis at the early stage of architecture design. It is also expected that the catalogue data based on an actual process technology is valuable for education.
Kenichi OKADA Kento YAMAOKA Hidetoshi ONODERA
This paper proposes a model to calculate statistical gate-delay variation caused by intra-chip and inter-chip variabilities. The variation of each gate delay directly influences the circuit-delay variation, so it is important to characterize each gate-delay variation accurately. Every transistor in a gate affects transient characteristics of the gate, so it is indispensable to consider an intra-gate variability for the modeling of gate-delay variation. This effect is not captured in a statistical delay analysis reported so far. Our model considers the intra-gate variability by sensitivity constants. We evaluate our modeling accuracy, and we show some simulated results of a circuit delay variation.
Recently, millimeter-wave energy has attracted much attention as a new and novel energy source for materials processing. In the present paper, several unique features of millimeter-wave heating in materials processing are reviewed briefly and development of materials processing machines by mm-wave radiation is also described. In the application of mm-wave heating, sintering of high quality alumina ceramics having a high bending strength of about 800 MPa are first demonstrated and followed by preparation of aluminum nitride with a high thermal conductivity over 200 W/(mK) at a sintering temperature lower by 473-573 K than the conventional method, by which this processing can be expected to be one of the environment-conscious energy saving processes. A newly developed post-annealing process with mm-wave radiation is described, in which crystallization of amorphous perovskite oxide films prepared by plasma sputtering was attained at temperatures lower than that by the conventional heating and the dielectric constant of post-annealed SrTiO3 (STO) films by mm-wave radiation were drastically improved.
Takeshi SHIRAISHI Toshio NISHIKAWA Kikuo WAKINO Toshihide KITAZAWA
A novel hybrid numerical method, which is based on the extended spectral domain approach combined with the mode-matching method, is applied to evaluate the scattering parameter of waveguide discontinuities. The formulation procedure utilizes the biorthogonal relation in the transformation, and the Green's functions in the spectral domain are obtained easily even in the inhomogeneous lossy regions. The present method does not include the approximate perturbational scheme, and it can evaluate accurately and stably the scattering parameters of either for the thin or thick obstacles made of the wide variety of materials, the lossless dielectrics to highly conductive media, in short computation time. The physical phenomena of transmission through the lossy obstacles are investigated by numerical computations. The results are compared with FEM where FEM computations are feasible, although the FEM computations cannot cover the whole performances of the present method. The good agreement is observed in the corresponding range. The matrix size in this method is smaller than that of other methods. Therefore, the present method is numerically efficient and it would be able to apply for the integrated evaluation of a successive discontinuity. The resonant characteristics of rectangular waveguide cavity are analyzed accurately taking the conductor losses into consideration.
This investigation proposes a new multiplication algorithm in the finite field GF(2m) over the polynomial basis, in which the irreducible xm +xn + 1 with gcd(m,n) = 1 generates the field GF(2m). The algorithm involves two steps--the intermediate multiplication and the modulo reduction. In the first step, the intermediate multiplication algorithm permutes a polynomial to construct the full-bit-parallel systolic intermediate multiplier. The circuit is identical of m2 cells, each cell is identical of one 2-input AND gate, one 2-input XOR gate, and four 1-bit latches. In the second step, based on the results of the intermediate multiplication in the first step, the modulo reduction circuit is built using regular and simple reduction operations. The latency of the proposed multiplier requires m + k + 1 clock cycles, where k = + 1. Notably, the latency can be very low if n is in the range 1 n . For the computing multiplication in GF(2m), the novel multiplier exhibits much lower latency than the existing systolic multipliers, and is well suited to VLSI systems due to their regular interconnection pattern, modular structure and fully inherent parallelism.
Toshiyuki MIYAMOTO Sadatoshi KUMAGAI
Autonomous distributed manufacturing systems(ADMS) consist of multiple intelligent components with each component acting according to its own judgments. The ADMS objective is to realize more agile and adaptive manufacturing systems. This paper presents the introduction of context-dependent agents (CDAs) in ADMS, and switch strategies depending on system conditions to achieve better performance can be realized by agents that use the same strategies under all system conditions. For the real-time job scheduling problem, the present paper recalls a basic CDA architecture, and presents the results of an extensive empirical evaluation its performance relative to other rule-based schemes based on several common indices for real-time dispatch.
Toshiyuki MIYAMOTO Syoji YAMASHITA Sadatoshi KUMAGAI Hideaki OHTA Koichi FUKUMOTO Yoichi NAGAO
The present paper discusses an assembly line balancing problem (ALBP). ALBP discussed up to now does not consider rack spaces where tools or parts are stored. We introduce an extended resource planning and assembly line balancing problem that takes the rack space into account. An exact search method for solving the problem by using a graph structure, and a heuristics for the method are proposed. The proposed method is evaluated by computational experiments.
The auction is a popular way of trading. Despite of the popularity of the auction, only a small number of papers have addressed the protocol which realize the double auction. In this paper, we propose a new method of double auction which improves the algorithm of the existing double auction protocol. Our new method is based on the idea of number comparison which is realized by homomorphic encryption. The new method solves the problem of the privacy of losing bids found in the existing algorithm. The buyers and the sellers can embed a random number in their bidding information by the use of the homomorphic encryption. The players in an auction cannot get anyone else's bidding information. The new method is more efficient than the existing ones. Our new method satisfies the criteria for the auction protocol.
Norimasa NAKASHIMA Mitsuo TATEIBA
The boundary element method (BEM), a representative method of numerical calculation of electromagnetic wave scattering, has been used for solving boundary integral equations. Using BEM, however, we finally have to solve a linear system of L equations expressed by dense coefficient matrix. The floating-point operation is O(L2) due to a matrix-vector product in iterative process. Greengard-Rokhlin's fast multipole algorithm (GRFMA) can reduce the operation to O(L). In this paper, we describe GRFMA and its floating-point operation theoretically. Moreover, we apply the fast Fourier transform to the calculation processes of GRFMA. In numerical examples, we show the experimental results for the computation time, the amount of used memory and the relative error of matrix-vector product expedited by GRFMA. We also discuss the convergence and the relative error of solution obtained by the BEM with GRFMA.
Shenjian LIU Qun WAN Yingning PENG
In this paper, we consider the problem of bearing estimation for spatially distributed sources in unknown spatially-correlated noise. Assumed that the noise covariance matrix is centro-Hermitian, a differential denoising scheme is developed. Combined it with the classic DSPE algorithm, a differential denoising estimator is formulated. Its modified version is also derived. Exactly, the differential processing is first imposed on the covariance matrix of array outputs. The resulting differential signal subspace (DSS) is then utilized to weight array outputs. The noise components orthogonal to DSS are eliminated. Based on eigenvalue decomposition of the covariance matrix of weighted array outputs, the DSPE null spectrum is constructed. The asymptotic performance of the proposed bearing estimator is evaluated in a closed form. Moreover, in order to improve the performance of bearing estimation in case of low signal-to-noise ratio, a modified differential denoising estimator is proposed. Simulation results show the effectiveness of the proposed estimators under the low SNR case. The impacts of angular spread and number of sensors are also investigated.
Chun Jen LIN Chien-Ching CHIU Yi-Da WU
In this paper, an efficient optimization algorithm for solving the inverse problem of a two-dimensional lossless homogeneous dielectric object is investigated. A lossless homogeneous dielectric cylinder of unknown permittivity scatters the incident wave in free space and the scattered fields are recorded. Based on the boundary condition and the incident field, a set of nonlinear surface integral equation is derived. The imaging problem is reformulated into optimization problem and the steady-state genetic algorithm is employed to reconstruct the shape and the dielectric constant of the object. Numerical results show that the permittivity of the cylinders can be successfully reconstructed even when the permittivity is fairly large. The effect of random noise on imaging reconstruction is also investigated.
Takeshi TATEYAMA Seiichi KAWATA Hideaki OHTA
In this paper, a new grouping method for Group Technology using Self-Organizing Map (SOM) is proposed. The purpose of our study is to divide machines in a factory into any number of cells so that the machines in each cell can process a similar set of parts to increase productivity. A main feature of our method is to specify not only the number of the cells but also the maximum and minimum numbers of machines in a cell. Some experimental results show effectiveness of our proposed algorithm.
Akihiko SUGIURA Keiichi YONEMURA
Aging is progressing in our country. Cerebral disease poses a serious problem. Viewing this problem objectively, we can say that support of aging and cerebral disease patients is a useful research theme. To the present, we have done rank evaluation of cerebral disease using synthetic face picture images. This study assesses cognitive ability and expression control ability for intoxication, which is known to impair thinking, cognition, and memory ability. We also examine correspondence of intoxication to cerebral disease. Measurement of cognitive ability corresponds to observation of an internal condition; the measurement of expression control ability corresponds to observation of an external condition. In measurement of cognitive ability, we simulated early stage symptoms of vascular dementia in the second stage of BAC. Also, decreased cognitive ability occurs from the first stage of BAC on face recognition to figure and language. Moreover, face test results show significant difference between decrease in the first stage of BAC and one in the second stage of BAC. These results indicate the possibility of rank evaluation and early stage detection of vascular dementia using a face picture image. From measurement of expression control ability, we obtained the result that we can judge whether a subject has reached second stage of BAC by observing an expression's strength of smile. The second stage of BAC shows symptoms similar to those of vascular dementia. We found the possibility that smile is valid as one externally-observable index for detection of cerebral disease.
Yong Up LEE Joong-Hoo PARK Yeongjun SEO
The performance enhancement technology for indoor-to-outdoor wireless communication systems is discussed in this study. In outdoor communication systems, transmitted signals may be severely degraded mainly by multipath fading effect of the channel and this problem can be overcome using conventional multiple antenna technology and array signal processing algorithms. But, since channel characteristics depend on both multipath fading and angle spread in indoor-to-outdoor communication systems, conventional algorithms which do not consider the effect caused by angle spread cannot give good results. In this letter, characteristics of indoor-to-outdoor channels are analyzed and a channel model suitable for this situation is proposed. And a new array antenna processing algorithm exploiting the concept of the mean steering vector is presented and the system performance is analyzed. It can be shown that the proposed algorithm outperforms conventional methods through computer simulations for the case in which signals sent from indoor transmitters arrive at outdoor receivers.
The QoS(Quality of Service) guarantee mechanism is one of critical issues in the wireless network. Real-time applications like VoIP(Voice over IP) in All-IP networks need smooth handoffs in order to minimize or eliminate datagram loss as a Mobile Host(MH) transitions between network links. In this paper, we design a new DB(Dynamic Buffering) mechanism for IPv6 by which an MH can request that the router on its current subnet buffers packets on its behalf while the MH completes registration procedures with the router of a new subnet. Performance results show that our proposed buffering scheme with a dynamic buffer space allocation is quite appropriate for mobile Internet, or the All-IP environment in terms of the datagram loss rate and average waiting time.
Tomoyuki OHTA Munehiko FUJIMOTO Shinji INOUE Yoshiaki KAKUDA
Recently, in wired networks, a hierarchical structure has been introduced to improve management and routing. In ad hoc networks, we introduce a hierarchical structure to achieve the same goal. However, it is difficult to introduce the hierarchical structure because all mobile hosts are always moving around the network. So, we proposed the clustering scheme to construct the hierarchical structure before. In this paper, we propose a new hierarchical routing protocol called Hi-TORA based on the clustering scheme. And we show the experimental evaluation of Hi-TORA with respect to the number of control packets, accuracy of packet delivery and hop counts in comparison with TORA.
Rachaporn KEINPRASIT Prabhas CHONGSTITVATANA
In this paper an algorithm based on Ant Colony Optimization techniques called Ants on a Tree (AOT) is introduced. This algorithm can integrate many algorithms together to solve a single problem. The strength of AOT is demonstrated by solving a High-Level Synthesis problem. A High-Level Synthesis problem consists of many design steps and many algorithms to solve each of them. AOT can easily integrate these algorithms to limit the search space and use them as heuristic weights to guide the search. During the search, AOT generates a dynamic decision tree. A boosting technique similar to branch and bound algorithms is applied to guide the search in the decision tree. The storage explosion problem is eliminated by the evaporation of pheromone trail generated by ants, the inherent property of our search algorithm.
Shin-ichiro MORI Tomoaki TSUMURA Masahiro GOSHIMA Yasuhiko NAKASHIMA Hiroshi NAKASHIMA Shinji TOMITA
This paper describes the architecture of ReVolver/C40 a scalable parallel machine for volume rendering and its prototype implementation. The most important feature of ReVolver/C40 is view-independent real time rendering of translucent 3D object by using perspective projection. In order to realize this feature, the authors propose a parallel volume memory architecture based on the principal axis oriented sampling method and parallel treble volume memory. This paper also discusses the implementation issues of ReVolver/C40 where various kinds of parallelism extracted to achieve high-perfromance rendering are explained. The prototype systems had been developed and their performance evaluation results are explained. As the results of the evaluation of the prototype systems, ReVolver/C40 with 32 parallel volume memory is estimated to achieve more than 10 frame per second for 2563 volume data on 2562 screen by using perspective projection. The authors also review the development of ReVolver/C40 from several view points.
Alan O'RIORDAN Gareth REDMOND Thierry DEAN Mathias PEZ
Field Configurable Self-assembly is a novel programmable force field based heterogeneous integration technology. Herein, we demonstrate application of the method to rapid, parallel assembly of similar and dissimilar sub-200 µm GaAs-based light emitting diodes at silicon chip substrates. We also show that the method is compatible with post-process collective wiring techniques for fully planar hybrid integration of active devices.
Mamoru OHARA Masayuki ARAI Satoshi FUKUMOTO Kazuhiko IWASAKI
An approach is proposed for constructing a dependable server cluster composed only of server nodes with all nodes running the same algorithm. The cluster propagates an IP multicast address as the server address, and clients multicast requests to the cluster. A local proxy running on each client machine enables conventional client software designed for unicasting to communicate with the cluster without having to be modified. Evaluation of a prototype system providing domain name service showed that a cluster using this technique has high dependability with acceptable performance degradation.