First, we show that the necessary and sufficient condition for the existence of a balanced bowtie decomposition of the complete tripartite multi-graph λ Kn1,n2,n3 is (i) n1=n2=n3 0 (mod 6) for λ 1,5 (mod 6), (ii) n1=n2=n3 0 (mod 3) for λ 2,4 (mod 6), (iii) n1=n2=n3 0 (mod 2) for λ 3 (mod 6), and (iv) n1=n2=n3 2 for λ 0 (mod 6). Next, we show that the necessary and sufficient condition for the existence of a balanced trefoil decomposition of the complete tripartite multi-graph λ Kn1,n2,n3 is (i) n1=n2=n3 0 (mod 9) for λ 1,2,4,5,7,8 (mod 9), (ii) n1=n2=n3 0 (mod 3) for λ 3,6 (mod 9), and (iii) n1=n2=n3 3 for λ 0 (mod 9).

Recently, Vatan, Roychowdhury and Anantram have presented two types of revised versions of the Calderbank-Shor-Steane code construction, and have also provided an exhaustive procedure for determining bases of quantum error-correcting codes. In this paper, we investigate the revised versions given by Vatan et al., and point out that there is no essential difference between them. In addition, we propose an efficient algorithm for searching for bases of quantum error-correcting codes. The proposed algorithm is based on some fundamental properties of classical linear codes, and has much lower complexity than Vatan et al.'s procedure.

In current-mode signal processing, a companding integrator is attractive from the viewpoint of linearity under a low power supply voltage. In this paper, new instantaneous companding integrators using MOSFET's are proposed. The companding integrator utilizes a nature of MOSFET square law. HSPICE simulation results demonstrate several advantages of the proposed circuits.

In this study, we consider a filtering method for image sequence degraded by additive Gaussian noise and/or impulse noise (i.e., mixed noise). For removing the mixed noise from the 1D/2D signal, weighted median filters are well known as a proper choice. We have also proposed a filtering tool based on the weighted median filter with a data-dependent method. We call this data-dependent weighted median (DDWM) filters. Nevertheless, the DDWM filter, its weights are controlled by some local information, is not enough performance to restore the image sequence degraded by the noise. The reason is that the DDWM filter is not able to obtain good filtering performance both in the still and moving regions of an image sequence. To overcome above drawback, we add motion information as a motion detector to the local information that controls the weights of the filters. This new filter is proposed as a Video-Data Dependent Weighted Median (Video-DDWM) filter. Through some simulations, the Video-DDWM filter is shown to give effective restoration results than that given by the DDWM filtering and the conventional filtering method with a motion-conpensation (MC).

Using decision trees to fill the missing values in data has been shown experimentally to be useful in some domains. However, this is not the general case. In other domains, using decision trees for imputing missing attribute values does not outperform other methods. Trying to identify the reasons behind the success or failure of the various methods for filling missing values on different domains can be useful for deciding the technique to be used when learning concepts from a new domain with missing values. This paper presents a technique by which to approach to previous goal and presents the results of applying the technique on predicting the success or failure of a method that uses decision trees to fill the missing values in an ordered manner. Results are encouraging because the obtained decision tree is simple and it can even provide hints for further improvement on the use of decision trees to impute missing attribute values.

We propose a vector-pipeline processor VP-DSP for low-rate videophones which can encode and decode 10 frames/sec. of QCIF through a 29.2 kbps low-rate line. We have already fabricated a VP-DSP LSI by a 0.35 µm CMOS process. The area of the VP-DSP core is 4.26 mm2. It works properly at 25 MHz/1.6 V with a power consumption of 49 mW. Its peak performance is up to 400 MOPS, 8.2 GOPS/W.

The transmission S-parameter, S21, between dipole elements on a rectangular finite ground plane is calculated by the MoM with planar-segments in the horizontally and vertically polarized configurations. Supposed a 1/10 scaling, the frequency range is selected 0.15-0.8 GHz. The size of the finite ground plane is 40 cm 100 cm. The dipole-element length is 18.8 cm (half-wavelength at 0.8 GHz). The distance between dipole elements is 30 cm. The results are compared to the calculated results with the conventional MoM-GTD hybrid method and also the measured results with a TRL-calibrated network analyzer. It makes clear that the MoM-GTD hybrid method is not applicable to a small ground plane in the vertically polarized configuration. The results calculated by the MoM with planar-segments agree well to the measured results both in the horizontal and vertical polarizations. The results show that the size of the finite ground plane for the vertical polarization should be much larger than for the horizontal polarization.

One major breakthrough on the communication society recently is the extension of networking from wired to wireless networks. This has made possible creating a mobile distributed computing environment and has brought us several new challenges in distributed protocol design. Obviously, wireless networks do have some fundamental differences from wired networks that need to be paid special attention of, such as lower communication bandwidth compared to wired networks, limited electrical power due to battery capacity, and mobility of processes. These new issues make traditional recovery algorithm unsuitable. In this paper, we propose an efficient algorithm with O(nr) message complexity where O(nr) is the total number of mobile hosts (MHs) related to the failed MH. In addition, these MHs only need to rollback once and can immediately resume its operation without waiting for any coordination message from other MHs. During normal operation, the application message needs O(1) additional information when it transmitted between MHs and mobile support stations (MSSs). Each MSS must keep an ntotal_h*n cell_h dependency matrix, where O(ntotal_h) is the total number of MHs in the system and ncell_h is the total number of MHs in its cell. Finally, one related issue of resending lost messages is also considered.

This paper deals with a study of a problem for finding the minimum-cost spanning tree with a response-time bound. The relation of cost and response-time is given as a monotonous decreasing and convex function. Regarding communication bandwidth as cost in an information network, this problem means a minimum-cost tree shaped routing for response-time constrained broadcasting, where any response-time from a root vertex to other vertex is less than a given time bound. This problem is proven to be NP-hard and consists of the minimum-cost assignment to a rooted tree and the minimum-cost tree finding. A nonlinear programming algorithm solves the former problem for the globally optimal solution. For the latter problem, different types of heuristic algorithms evaluate to find a near optimal solution experimentally.

The head tissue heterogeneity required in the spatial peak specific absorption rate (SAR) assessment for portable telephones was investigated by using the FDTD method in conjunction with an MRI-based human head model. The tissue heterogeneity of the head model was changed from one type of tissue to 17 types of tissue. The results showed that, at 900 MHz and 2 GHz, the homogeneous modeling results in an underestimate about 20% for the λ/2 monopole antenna portable telephones and an overestimate to the same extent for the λ/4 monopole or helical antenna portable telephones. A head model with a simple skin-fat-muscle-bone-brain structure seems to be sufficient to obtain a fairly accurate one-gram or ten-gram averaged spatial peak SAR value in computational dosimetry for portable telephone compliance.

We study the performance of oblivious routing algorithms that follow minimal (shortest) paths, referred to as minimal oblivious routing algorithms in this paper, using competitive analysis on a d-dimensional, N = 2d-node hypercube. We assume that packets are injected into the hypercube arbitrarily and continuously, without any (e.g., probabilistic) assumption on the arrival pattern of the packets. Minimal algorithms reduce the total load in the network in the first place and they preserve locality. First we show that the well known deterministic oblivious routing algorithm, namely, the greedy routing algorithm, has competitive ratio Ω(N1/2). Then we show a problem lower bound of Ω(Nlog 2 (5/4)/log5 N). We also give a natural randomized minimal oblivious routing algorithm whose competitive ratio is close to the problem lower bound we provide.

This paper investigates a hierarchical property based on the number of inkdots in the accepting powers of sublogarithmic space-bounded multi-inkdot two-way alternating Turing machines with only universal states. For each k1 and any function L(n), let strong-2UTMk(L(n)) (weak-2UTMk(L(n))) be the class of sets accepted by strongly (weakly) L(n) space-bounded k-inkdot two-way alternating Turing machines with only universal states. We show that for each k1, strong-2UTMk+1(log log n) - weak-2UTMk(o(log n)) Ø.

Private information retrieval for k 1 databases (denoted by (k,l)-PIR for short) is a protocol that (1) a user sends an l tuple query to each of k noncommunicating replicated databases; (2) each database responds the user with an answer corresponding to the l tuple query; (3) the user privately retrieve any single bit out of the n bits of data stored in k databases. In this model, "privacy" implies that the user retrieves the bit he is interested in but releases to each database nothing about which bit he wishes to get. In general, the efficiency of (k,l)-PIR is measured by the total amount of bits exchanged between the user and the k databases, but few about its lower bounds are known except for restricted cases. In this paper, we classify (k,l)-PIR into a linear type, a multilinear type, and an affine type with respect to the relationship between queries to each database (made by the user) and answers to the user (made by each database), and show that (1) the lower bound for the communication complexity of any multilinear type (k,l)-PIR is Ω(n1/(l+1)) (Theorem 3.1); (2) the lower bound for the communication complexity of any linear type (k,l)-PIR is Ω(n) (Corollary 3.2); (3) the lower bound for the communication complexity of any affine type (k,l)-PIR is Ω(n1/(l+1)) (Theorem 4.2).

We propose a blind source separation algorithm for the mixture of finite alphabet sources where sensors are less than sources. The algorithm consists of an update equation of an estimated mixing matrix and enumeration of the inferred sources. We present the bound of a step size for the stability of the algorithm and two methods of assignment of the initial point of the estimated mixing matrix. Simulation results verify the proposed algorithm.

In this paper, we present a computer-aided diagnosis (CAD) system to automatically detect lung cancer candidates at an early stage using a present and a past helical CT screening. We have developed a slice matching algorithm that can automatically match the slice images of a past CT scan to those of a present CT scan in order to detect changes in the lung fields over time. The slice matching algorithm consists of two main process: the process of extraction of the lungs, heart, and descending aorta and the process of matching slices of the present and past CT images using the information of the lungs, heart, and descending aorta. To evaluate the performance of this algorithm, we applied it to 50 subjects (total of 150 scans) screened between 1993 and 1998. From these scans, we selected 100 pairs for evaluation (each pair consisted of scans for the same subject). The algorithm correctly matched 88 out of the 100 pairs. The slice images for the present and past CT scans are displayed in parallel on the CRT monitor. Feature measurements of the suspicious regions are shown on the relevant images to facilitate identification of changes in size, shape, and intensity. The experimental results indicate that the CAD system can be effectively used in clinical practice to increase the speed and accuracy of routine diagnosis.

As one form of electronic commerce, the scale of online trading in stocks is rapidly growing. Although brokers lie between the customers as trustees in the current market, retrenchment of broker seems inevitable. This paper proposes a protocol that allows trading to proceed with only the market and the customers. We show the required characteristics for this type of trading at first. Next, to fulfil these characteristics, we apply an electronic auction protocol and digital signatures. The result is a trading protocol with security equivalent to that the current trading system.

Can we find in polynomial time an elliptic curve of a given order over a finite field? This paper is concerned with this question which is open since 1986. Consider the partial multivalued function that outputs such an elliptic curve. We characterize the difficulty of computing this function, and show that the polynomial time hierarchy collapses if sat reduces to this function with respect to the polynomial time Turing reducibility, where sat is the partial multivalued function that on input a Boolean formula, outputs a satisfying assignment. We also give a problem that is equivalent to the open question under the Extended Riemann Hypothesis.

In this paper, we propose a realtime concatenation technique between basic skeletal motions obtained by the motion capture technique and etc. to generate a lifelike behavior for a humanoid character (avatar). We execute several experiments to show the advantage and the property of our technique and also report the results. Finally, we describe our applied system called WonderSpace which leads participants to the exciting and attractive virtual worlds with humanoid characters in cyberspace. Our concatenation technique has the following features: (1) based on a blending method between a preceding motion and a succeeding motion by a transition function, (2) realizing "smooth transition," "monotone transition," and "equivalent transition" by the transition function called paste function, (3) generating a connecting interval by making the backward and forward predictions for the preceding and succeeding motions, (4) executing the prediction under the hypothesis of "the smooth stopping state" or "the state of connecting motion", (5) controlling the prediction intervals by the parameter indicating the importance of the motion, and (6) realizing realtime calculation.

This paper proposes a method for implementing a metric computation accelerator for fractal image compression using reconfigurable hardware. The most time-consuming part in the encoding of this compression is computation of metrics among image blocks. In our method, each processing element (PE) configured for an image block accelerates these computations by pipeline processing. Furthermore, by configuring the PE for a specific image block, we can reduce the number of adders, which are the main computing elements, by a half even in the worst case.

The need for electronic sealed-bid auction services with quantitative competition is increasing. This paper proposes a new method that combines one-way functions and a bit commitment technique for quantitative competitive sealed-bid auctions. Since each modular exponentiation is replaced with a one-way function, the proposed method's computational time is one forty thousandth that of the former methods and the proposed method suits mass bidder systems.