In this paper an analysis of component and system reliability for lattice systems is proposed when component failures are not statistically independent. We deal the case that the failure rate of a component depends on the number of the adjacent failed components. And we discuss the maintainability of the system when a failed component is replaced by a spare component. At first we discuss the approximated reliability of each component. Then we estimate the mean number of failed components. Furthermore, the system reliability is approximated by using the component reliability.

In this paper, we propose a new robust model predictive control (MPC) technique for linear parameter varying (LPV) systems expressed as linear systems with feedback parameters. It is based on the minimization of the upper bound of finite horizon cost function using a new parameter dependent terminal weighting matrix. The proposed parameter dependent terminal weighting matrix for norm-bounded uncertain models provides a less conservative condition for terminal inequality. The optimization problem that satisfies the terminal inequality is solved by semi-definite programming involving linear matrix inequalities (LMIs). A numerical example is included to illustrate the effectiveness of the proposed method.

This paper presents a method for tuning the structure of a causal network (CN) to evaluate a learner's profile for a learning assistance system that employs hierarchically structured learning material. The method uses as an initial CN structure causally related inter-node paths that explicitly define the learning material structure. Then, based on this initial structure other inter-node paths (sideway paths) not present in the initial CN structure are inferred by referring to the learner's database generated through the use of a learning assistance system. An evaluation using simulation indicates that the method has an inference probability of about 63% and an inference accuracy of about 30%.

This paper presents a method of simple adaptive control (SAC) using neural networks for a class of nonlinear systems with bounded-input bounded-output (BIBO) and bounded nonlinearity. The control input is given by the sum of the output of the simple adaptive controller and the output of the neural network. The neural network is used to compensate for the nonlinearity of the plant dynamics that is not taken into consideration in the usual SAC. The role of the neural network is to construct a linearized model by minimizing the output error caused by nonlinearities in the control systems. Furthermore, convergence and stability analysis of the proposed method is performed. Finally, the effectiveness of the proposed method is confirmed through computer simulation.

Diseases in the gastro-intestinal track are becoming more prevalent. In order to diagnose a patient, the various signals of the digestive organ, such as temperature, pH, and pressure, can offer helpful information. The variation of a pressure signal of the gastro-intestinal track can offer information about digestive troubles or provide clues about diseases. This paper presents a wireless system for the pressure monitoring system, which includes a swallow-type pressure capsule and the external receiving system. A transmitter, a transmitting antenna (Helix), a receiver, and a receiving antenna (Loop) were designed and fabricated in consideration of the MPE, power consumption, system size, signal to noise ratio and modulation method. The wireless system designed and implemented for the pressure monitoring system was verified by in-vivo experiments. As a result, we found each organ has its own characteristic pressure fluctuation.

We investigated performance improvement in a cellular system by introducing direct communication between terminals. Previous research has indicated that direct communication efficiently uses channels; however, this is not always so. We studied two factors that affect how much efficiency improves. One is the distribution of terminals. We defined some typical distributions with localization of terminals and analyzed how the difference between the distributions affected the performance improvement by direct communication. Another factor is the mobility of terminals, because mobility shortens the length of time during which terminals are directly connected. We analyzed how mobility affected performance improvement by direct communication. For the analyses, we used some theoretical techniques.

This paper proposes a gonio-spectral imaging system for measuring light reflection on an object surface by using two robot arms, a multi-band lighting system, and a monochrome digital camera. It allows four degrees of freedom in incident and viewing angles necessary for full parametrization of a reflection model function. Spectral images captured for various incident and viewing angles are warped as if they were all captured from the same viewing direction. The intensity of reflected light is thus recorded in a normalized image form for any incident and viewing directions. The normalized images are used to estimate reflection model parameters at each surface point. To ensure point-wise reflection modeling, a calibration method is also proposed based on a geometrical model of the robot arms and camera. The proposed system can deal with objects with surface texture. Experiments are done on system calibration, reflection model, and spectral estimation. The results using colored objects show the feasibility of the proposed imaging system.

An atmospheric visibility measurement system capable of quantifying the most common operating range of onboard exteroceptive sensors is a key parameter in the creation of driving assistance systems. This information is then utilized to adapt sensor operations and processing or to alert the driver that the onboard assistance system is momentarily inoperative. Moreover, a system capable of either detecting the presence of fog or estimating visibility distances constitutes in itself a driving aid. In this paper, we first present a review of different optical sensors likely to measure the visibility distance. We then present our stereovision based technique to estimate what we call the "mobilized visibility distance". This is the distance to the most distant object on the road surface having a contrast above 5%. In fact, this definition is very close to the definition of the meteorological visibility distance proposed by the International Commission on Illumination (CIE). The method combines the computation of both a depth map of the vehicle environment using the "v-disparity" approach and of local contrasts above 5%. Both methods are described separately. Then, their combination is detailed. A qualitative evaluation is done using different video sequences. Finally, a static quantitative evaluation is also performed thanks to reference targets installed on a dedicated test site.

This paper proposes a novel compressing and expanding (companding) system for OFDM wireless communications that minimizes the compression distortion and so reduces the peak power of OFDM symbols. OFDM systems suffer from large variations in instantaneous peak power. Such transients distort the signals when they are passed through a nonlinear high power amplifier (HPA) prior to transmission. Existing companding systems are far from perfect since the receiver can not accurately estimate the degree of compression applied by the transmitter and thus can not regenerate the original signal by expansion; the key problems are the band pass filter (BPF), HPA, and the noise component enhanced by the channel compensation filter. In the proposed companding system, each symbol is divided into segments, and series of consecutive segments are grouped into clusters. Each cluster is multiplied by a weight equal to the inverse of the largest instantaneous power within the cluster. The receiver estimates the weight used for each time cluster. The weights for all clusters are averaged to mitigate the weight estimation error. As a result, the proposed expander can accurately estimate the weights used and thus well suppress the compression distortion.

Broadcast encryption technology enables a sender to send information securely to a group of receivers excluding specified receivers over a broadcast channel. In this paper, we propose a new key-tree structure based on Rabin cryptosystem, and an access control scheme using the structure. We show the security of the access control scheme and construct a new broadcast encryption scheme based on it. The proposed broadcast encryption scheme is a modification of the complete subtree method and it reduces the number of keys a receiver stores to one. There have been proposed some modifications of the complete subtree method which minimize the number of keys for a receiver to one, and the most efficient one among them with respect to the computational overhead at receivers is based on RSA cryptosystem. The computational overhead at receivers in our scheme is around log2e times smaller than the most efficient previously proposed one, where e is a public exponent of RSA, and the proposed scheme is the most efficient among tree based one-key schemes. This property is examined by experimental results. Our scheme achieves this reduction in the computational overhead in exchange for an increase in the size of nonsecret memory by [log n * few (e.g. eight)] bits, where n is the total number of receivers.

If a logic circuit was specialized to a specific input, the derived circuit would be faster and smaller than the original. This study presents various designs of a key-specific AES encryption circuit. In our iterative design, 41% of the logic gates and 20% of RAM were reduced, while 24% more performance was derived. In our pipelined design, 54% of the logic gates and 20% of RAM were reduced, while 74% higher performance was achieved. The results on DES encryption circuits are also presented for comparison.

Various mixed-signal very-high-speed integrated circuits have been developed using InP DHBTs. These circuits have been designed for fiber-optic 43 Gbit/s transmissions applications. They include: on the transmitting side, a clocked driver and an EAM driver, as well as a PSBT/DQPSK precoder; on the receiving side, a sensitive decision circuit, a limiting amplifier and an eye monitor. System experiments made possible by these circuits include a 6 Tbit/s transmission on >6000 km distance.

In this paper, we propose a new method to enhance the fault-tolerance of the Content Addressable Network (CAN), which is known as a typical pure P2P system based on the notion of Distributed Hash Table (DHT). The basic idea of the proposed method is to introduce redundancy to the management of index information distributed over the nodes in the given P2P network, by allowing each index to be assigned to several nodes, which was restricted to be one in the original CAN system. To keep the consistency among several copies of indices, we propose an efficient synchronization scheme based on the notion of labels assigned to each copy in a distinct manner. The performance of the proposed scheme is evaluated by simulation. The result of simulations indicates that the proposed scheme significantly enhances the fault-tolerance of the CAN system.

This paper studies the problem of the relations between existence conditions of common quadratic and those of common infinity-norm Lyapunov functions for sets of discrete-time linear time-invariant (LTI) systems. Based on the equivalence between the robust stability of a class of time-varying systems and the existence of a common infinity-norm Lyapunov function for the corresponding set of LTI systems, the relations are determined. It turns out that although the relation is an equivalent one for single stable systems, the existence condition of common infinity-norm type is strictly implied by that of common quadratic type for the set of systems. Several existence conditions of a common infinity-norm Lyapunov functions are also presented for the purpose of easy checking.

For V-band applications, this paper presents a fully embedded multi-layer dielectric waveguide filter (DWGF) with very low insertion loss and small size, which does not need any more assemblies such as flip-chip bonding and bond wires. The top and bottom plane are grounded, and therefore, although we make a metal housing, there will be no resonance occurrences. Especially, the proposed structure is very suitable for MMICs interconnection because the in/output pads consist of conductor backed co-planar waveguide (CBCPW). The filter is formed incorporating metallized through holes in low temperature co-fired ceramic (LTCC) substrates with relative dielectric constant of 7.05. The total volume of the filter including transitions is 4.5 mm2.65 mm0.4 mm. A fabricated DWGF with four transitions shows an insertion loss and a return loss of 2.95 dB and less than 15 dB at the center frequency of 62.17 GHz, respectively. According to the authors' knowledge, the proposed filter shows the lowest insertion loss among the embedded multi-layer millimeter-wave filters ever reported for 60 GHz applications.

A new simply implemented collusion-attack free identity-based non-interactive key sharing scheme (ID-NIKS) has been proposed. A common-key can be shared by executing only once a modular exponentiation which is equivalent to RSA deciphering, and the security depends on the difficulty of factoring and the discrete logarithm problem. Each user's secret information can be generated by solving two simple discrete logarithm problems and synthsizing their solutions by linear combination. The detail comparison with the Maurer-Yacobi's scheme including its modified versions shows that the computational complexity to generate each user's secret information is much smaller and the freedom to select system parameters is much greater than that of the Maurer-Yacobi's scheme. Then our proposed scheme can be implemented very easily and hence it is suitable for practical use.

Recent work has shown that the usage of multiple antennas at the transmitter and receiver in a flat fading environment results in a linear increase in channel capacity. But increasing the number of antennas induces the higher hardware costs and computational burden. To overcome those problems, it is effective to select antennas appropriately among all available ones. In this paper, a new antenna selection method is proposed. The transmit antennas are selected so as to maximize the channel capacity using the genetic algorithm (GA) which is the one of the general random search algorithm. The results show that the proposed GA achieves almost the same performance as the optimal selection method with less computational amount.

Content-based publish/subscribe systems provide a useful alternative to traditional address-based communication due to their ability to decouple communication between participants. It has remained a challenge to design a scalable overlay supporting the complexity of content-based networks, while satisfying the desirable properties large distributed systems should have. This paper presents the design of Mirinae, a new structured peer-to-peer overlay mesh based on the interests of peers. Given an event, Mirinae provides a flexible and efficient dissemination tree minimizing the participation of non-matching nodes. We also present a novel ID space transformation mechanism for balancing routing load of peers even with highly skewed data, which is typical of the real world. Our evaluation demonstrates that Mirinae is able to achieve its goals of scalability, efficiency, and near-uniform load balancing. Mirinae can be used as a substrate for content-search and range query in other important distributed applications.

In this paper, we propose an interactive instruction system named IMPRESSION, which allows performance of interactive presentations using multimedia educational materials in class. In recent years, although many practices of educational methodology with information technology and presentation tools using multimedia resources as educational materials have come into common use, instructors can only present such materials in a slide-sheet form through the use of such presentation tools in class. Therefore, instructors can neither do formative evaluations nor can they present suitable materials according to students' reactions in class. Our proposed methodology employs a scenario-based approach in a double loop instructional design process to overcome such problems. Instructors design an instructional plan as a scenario, and subsequently implement and modify the plan through formative evaluation during the class. They then conduct a summative evaluation based on planned and implemented instructions for redesign. To realize our methodology, in this paper we propose and design an instruction system that provides functions to select and present multimedia materials interactively provided on the Internet during the class; we then record these instructions. After implementing it, we confirmed that we can conduct the class flexibly based on our methodology through its practical use in an actual classroom environment.

This letter presents two high-performance level-converting flip-flops (LCFF) for multi-VDD systems, indirect precharging flip-flop (IPFF) and multi-supply complementary pass-transistor flip-flop (MCPFF). Employing a simple precharging scheme, IPFF provides high operating speed. MCPFF, on the other hand, provides low power operations by implementing the edge-triggering function with complementary pass transistors. Performance comparison indicates that IPFF operates at the highest speed and MCPFF consumes the lowest power among the seven LCFFs under evaluation.