In peer-to-peer (P2P) content sharing, users can share their content by contributing their own resources to one another. However, since there is no incentive for contributing contents or resources to others, users may attempt to obtain content without any contribution. To motivate users to contribute their resources to the service, incentive-rewarding mechanisms have been proposed. On the other hand, emerging wireless technologies, such as IEEE 802.11 wireless local area networks, beyond third generation (B3G) cellular networks and mobile WiMAX, provide high-speed Internet access for wireless users. Using these high-speed wireless access, wireless users can use P2P services and share their content with other wireless users and with fixed users. However, this diversification of access networks makes it difficult to appropriately assign rewards to each user according to their contributions. This is because the cost necessary for contribution is different in different access networks. In this paper, we propose a novel incentive-rewarding mechanism called EMOTIVER that can assign rewards to users appropriately. The proposed mechanism uses an external evaluator and interactive learning agents. We also investigate a way of appropriately controlling rewards based on the system service's quality and managing policy.

We propose a new methodology of DOA (direction of arrival) estimation named SPIRE (Stepwise Phase dIfference REstoration) that is able to estimate sound source directions even if there is more than one source in a reverberant environment. DOA estimation in reverberant environments is difficult because the variance of the direction of an estimated sound source increases in reverberant environments. Therefore, we want the distance between microphones to be long. However, because of the spatial aliasing problem, the distance cannot be longer than half the wavelength of the maximum frequency of a source. DOA estimation performance of SPIRE is not limited by the spatial aliasing problem. The major feature of SPIRE is restoration of the phase difference of a microphone pair (M1) by using the phase difference of another microphone pair (M2) under the condition that the distance between the M1 microphones is longer than the distance between the M2 microphones. This restoration process enables the reduction of the variance of an estimated sound source direction and can alleviates the spatial aliasing problem that occurs with the M1 phase difference using direction estimation of the M2 microphones. The experimental results in a reverberant environment (reverberation time = about 300 ms) indicate that even when there are multiple sources, the proposed method can estimate the source direction more accurately than conventional methods. In addition, DOA estimation performance of SPIRE with the array length 0.2 m is shown to be almost equivalent to that of GCC-PHAT with the array length 0.5 m. SPIRE can executes DOA estimation with a smaller microphone array than GCC-PHAT. From the viewpoint of the hardware size and coherence problem, the array length is required to be as small as possible. This feature of SPIRE is preferable.

Rubbed polyimide films have been widely used as liquid crystal alignment films for liquid crystal displays. Washing after rubbing is essential to fabricate liquid crystal displays, and should affect alignment of liquid crystal as well as rubbing. We investigated the effects of rubbing condition and soaking in acetone on polyimide films by grazing incidence X-ray diffraction. It was found that soaking in acetone promoted crystallization of surface aligned polymers, and that the crystallization by acetone was dependent on the initial polymer alignment. The larger initial crystalline phase was, the more newly crystallization occurred by soaking. It was also revealed that the crystallization by soaking in acetone was completed within 1 min.

We report effects of washing rubbed polyimide film on the near surface. Especially we focused dependence of solvent. Rubbed polyimide films have been used as liquid crystal alignment films in Liquid crystal displays (LCDs), and in actual LCD panel fabrication washing on film surfaces after rubbing is essential process to remove dust and pollution. We investigated the effects of washing by grazing incidence X-ray diffraction (GIXD) measurements. In GIXD, the X-ray penetration into the polymer was changed from 8 nm (suface sensitive) to 4 nm (bulk sensitive) by variation of the X-ray incidence angle. It was found that crystallization near the surface induced by soaking was considerably dependent on solvent. However, in-plane distribution of the surface polymer chains of polyimide film was not found to be dependent on the solvents.

The design and analysis of block ciphers is an established field of study which has seen significant progress since the early 1990s. Nevertheless, what remains on an interesting direction to explore in this area is to design block ciphers with provable security against powerful known attacks such as differential and linear cryptanalysis. In this paper we introduce seven new block cipher structures, named Feistel-variant A, B, CLEFIA and MISTY-FO-variant A, B, C, D structures, and show that these structures are provably resistant against differential cryptanalysis. The main results of this paper are that the average differential probabilities over at least 2 rounds of Feistel-variant A structure and 1 round of Feistel-variant B structure are both upperbounded by p2, while the average differential probabilities over at least 5 rounds of CLEFIA, MISTY-FO-variant A, B, C and D structures are upperbounded by p4+2p5, p4, p4, 2p4 and 2p4, respectively, if the maximum differential probability of a round F function is p. We also give provable security for the Feistel-variant A, B and CLEFIA structures against linear cryptanalysis. Our results are attained under the assumption that all of components in our proposed structures are bijective. We expect that our results are useful to design block ciphers with provable security against differential and linear cryptanalysis.

In this paper we compare various parallel preconditioners such as Point-SSOR (Symmetric Successive OverRelaxation), ILU(0) (Incomplete LU) in the Wavefront ordering, ILU(0) in the Multi-color ordering, Multi-Color Block SOR (Successive OverRelaxation), SPAI (SParse Approximate Inverse) and pARMS (Parallel Algebraic Recursive Multilevel Solver) for solving large sparse linear systems arising from two-dimensional PDE (Partial Differential Equation)s on structured grids. Point-SSOR is well-known, and ILU(0) is one of the most popular preconditioner, but it is inherently serial. ILU(0) in the Wavefront ordering maximizes the parallelism in the natural order, but the lengths of the wavefronts are often nonuniform. ILU(0) in the Multi-color ordering is a simple way of achieving a parallelism of the order N, where N is the order of the matrix, but its convergence rate often deteriorates as compared to that of natural ordering. We have chosen the Multi-Color Block SOR preconditioner combined with direct sparse matrix solver, since for the Laplacian matrix the SOR method is known to have a nondeteriorating rate of convergence when used with the Multi-Color ordering. By using block version we expect to minimize the interprocessor communications. SPAI computes the sparse approximate inverse directly by least squares method. Finally, ARMS is a preconditioner recursively exploiting the concept of independent sets and pARMS is the parallel version of ARMS. Experiments were conducted for the Finite Difference and Finite Element discretizations of five two-dimensional PDEs with large meshsizes up to a million on an IBM p595 machine with distributed memory. Our matrices are real positive, i.e., their real parts of the eigenvalues are positive. We have used GMRES(m) as our outer iterative method, so that the convergence of GMRES(m) for our test matrices are mathematically guaranteed. Interprocessor communications were done using MPI (Message Passing Interface) primitives. The results show that in general ILU(0) in the Multi-Color ordering and ILU(0) in the Wavefront ordering outperform the other methods but for symmetric and nearly symmetric 5-point matrices Multi-Color Block SOR gives the best performance, except for a few cases with a small number of processors.

We have previously proposed a diffusion-type flow control mechanism as a solution for severely time-sensitive flow control required for high-speed networks. In this mechanism, each node in a network manages its local traffic flow using the basis of only the local information directly available to it, by using predetermined rules. In addition, the implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies show that our flow control mechanism with certain parameter settings works well in high-speed networks. However, to apply this mechanism to actual networks, it is necessary to clarify how to design a parameter in our control mechanism. In this paper, we investigate the range of the parameter and derive its optimal value enabling the diffusion-type flow control to work effectively.

SHACAL-2 is a 64-round block cipher with a 256-bit block size and a variable length key of up to 512 bits. It is a NESSIE selected block cipher algorithm. In this paper, we observe that, when checking whether a candidate quartet is useful in a (related-key) rectangle attack, we can check the two pairs from the quartet one after the other, instead of checking them simultaneously; if the first pair does not meet the expected conditions, we can discard the quartet immediately. We next exploit a 35-round related-key rectangle distinguisher with probability 2-460 for the first 35 rounds of SHACAL-2, which is built on an existing 24-round related-key differential and a new 10-round differential. Finally, taking advantage of the above observation, we use the distinguisher to mount a related-key rectangle attack on the first 44 rounds of SHACAL-2 . The attack requires 2233 related-key chosen plaintexts, and has a time complexity of 2497.2 computations. This is better than any previously published cryptanalytic results on SHACAL-2 in terms of the numbers of attacked rounds.

Sensor networks that carry heterogeneous traffics and are responsible for reporting very time-critical important events necessitate an efficient and robust data dissemination framework. Designing such a framework, that can achieve both the reliability and delay guarantee while preserving the energy efficiency, namely multi-constrained QoS (MCQoS), is a challenging problem. Although there have been many research works on QoS routing for sensor networks, to the best of our knowledge, no one addresses the above three service parameters all together. In this paper, we propose a new aggregate routing model and a distributed aggregate routing algorithm (DARA) that implements the model for achieving MCQoS. DARA is designed for multi-sink, multipath and location aware network architecture. We develop probabilistic models for multipath reliability constraint, sojourn time of a packet at an intermediary node and node energy consumption. Delay-differentiated multi-speed packet forwarding and in-node packet scheduling mechanisms are also incorporated with DARA. The results of the simulations demonstrate that DARA effectively improves the reliability, delay guarantee and energy efficiency.

To predict the thermal behavior of switchgear quickly, the Thermal Network Finite Difference Analysis method (TNFDA) is adopted in thermal analysis of AC contactor in the paper. The thermal network model is built with nodes, thermal resistors and heat generators, and it is solved using finite difference method (FDM). The main circuit and the control system are connected by thermal resistors network, which solves the problem of multi-sources interaction in the application of TNFDA. The temperature of conducting wires is calculated according to the heat transfer process and the fundamental equations of thermal conduction. It provides a method to solve the problem of boundary conditions in applying the TNFDA. The comparison between the results of TNFDA and measurements shows the feasibility and practicability of the method.

To design secure blockciphers, estimating immunity against differential attack and linear attack is essential. Recently, Diffusion Switching Mechanism (DSM) is proposed as a design framework to enhance the immunity of Feistel structure against differential attack and linear attack. In this paper, we give novel results on the effect of DSM on three generalized Feistel structures, i.e. Type-I, Type-II and Nyberg's structures. We first show a method for roughly estimating lower bounds of a number of active S-boxes in Type-I and Type-II structures using DSM. Then we propose an improved search algorithm to find lower bounds for generalized structures efficiently. Experimental results obtained by the improved algorithm show that DSM raises lower bounds for all of the structures, and also show that Nyberg's structure has the slowest diffusion effect among them when SP-type F-functions are used.

An all-optical phase multiplexing scheme for phase-modulated signals is proposed and experimentally demonstrated using four-wave mixing (FWM) in a highly-nonlinear fiber (HNLF). Two 10-Gb/s π/2-shifted differential phase-shift keying (DPSK) wavelength-division multiplexing (WDM) signals are experimentally demonstrated to be converted and phase-multiplexed into a 20-Gb/s differential quadrature phase-shift keying (DQPSK) signal with non-return-to-zero (NRZ) and return-to-zero (RZ) formats, respectively. Experimental results show that, due to phase-modulation-depth doubling effect and phase multiplexing effect in the FWM process, a DQPSK signal is successfully generated through the proposed all-optical phase multiplexing with improved receiver sensitivity and spectral efficiency.

AlN/GaN Metal Insulator Semiconductor Field Effect Transistors (MISFETs) were designed, simulated and fabricated. DC, S-parameter and power measurements were also performed. Drift-diffusion simulations using DESSIS compared AlN/GaN MISFETs and Al32Ga68N/GaN Heterostructure FETs (HFETs) with the same geometries. The simulation results show the advantages of AlN/GaN MISFETs in terms of higher saturation current, lower gate leakage and higher transconductance than AlGaN/GaN HFETs. First results from fabricated AlN/GaN devices with 1 µm gate length and 200 µm gate width showed a maximum drain current density of 380 mA/mm and a peak extrinsic transconductance of 85 mS/mm. S-parameter measurements showed that current-gain cutoff frequency (fT) and maximum oscillation frequency (fmax) were 5.85 GHz and 10.57 GHz, respectively. Power characteristics were measured at 2 GHz and showed output power density of 850 mW/mm with 23.8% PAE at VDS = 15 V. To the authors knowledge this is the first report of a systematic study of AlN/GaN MISFETs addressing their physical modeling and experimental high-frequency characteristics including the power performance.

As THz wave has the advantages of enough resolution and penetration to materials, it has been examined to be used for the imaging system. The propagation distance of THz wave is limited to be short. That is also the advantage for application to the indoor wireless communication etc. For the achievement of the ultra-high frequency oscillator (and concurrently transmitter) device, the properties of small, electronic excitation, the antenna constructed and being on the wafer are important. For the purpose, the Negative differential resistance Dual channel transistor (NDR-DCT) proposed by AIST is utilized. In this paper, as an initial theoretical analysis, we simulated the oscillation frequency of this device at about 100 GHz-1THz within the Terahertz band on which the above applications was expected. The equivalent circuit model of NDR-DCT was shown based on the analogy with the resonant tunnelling diode (RTDs), and the antenna as the resonance circuit part was designed by the numerical analysis. The possibility of the THz oscillation of this device was confirmed. The slit reflector that we proposed can realize the slot antenna on the device effectively and is suitable for three terminal structure semiconductor. its manufacturing is relatively easy.

A low distortion and low noise differential amplifier using the difference between the even- and odd-mode impedances is proposed. In order to realize an amplifier with high OIP3 and low NF characteristics, the impedance of the bias circuit should be low (<300 Ω) at the difference frequency and high (>4 kΩ) at the carrier frequency. Although the frequency response of the bias circuit impedance can only meet these conditions with difficulty, owing to the 20 MHz Tx signal bandwidth for 3G LTE, the proposed amplifier can achieve the impedance difference using the properties of a differential configuration where the difference frequency signal is the even-mode and the carrier frequency is the odd-mode. It has been demonstrated that the NF of the proposed amplifier, which has been fabricated in 0.18 µm SiGe BiCMOS technology operating at 2.14 GHz, can be kept to 1.6 dB or less and an OIP3 of 9.0 dBm can be achieved, which is 3 dB higher than that of a conventional amplifier, in the condition where the power gain is greater than 18 dB.

For wireless receivers, low-power 1.2-V 12-bit 100-MSPS pipeline ADCs are fabricated in 90-nm CMOS technology. To achieve low-power dissipation at 1.2 V without the degradation of SNR, the configuration of 2.5 bit/stage is employed with an I/Q amplifier sharing technique. Furthermore, single-stage pseudo-differential amplifiers are used in a Sample-and-Hold (S/H) circuit and a 1st Multiplying Digital-to-Analog Converter (MDAC). The pseudo-differential amplifier with two-gain-stage transimpedance gain-boosting amplifiers realizes high DC gain of more than 90 dB with low power. The measured SNR of the 100-MSPS ADC is 66.7 dB at 1.2-V supply. Under that condition, each ADC dissipates only 55 mW.

Although it is very important to conduct listening tests when constructing a practical sound field reproduction system based on wave field synthesis, listening tests are very expensive. A localization model of synthesized sound images that predicts the results of listening tests is proposed. This model reduces the costs of constructing a reproduction system because it makes it possible to omit the listening tests. The proposed model uses the precedence effect and predicts the direction of synthesized sound images based on the inter-aural time difference. A comparison of the results predicted by the proposed model and the localized results of listening tests shows that the model accurately predicts the localized results.

This paper presents a very wideband active RC polyphase filter (ARCPF). We propose a unit section of the ARCPF, which is an ordinary RCPF followed by opamps with parallel RC feedback. In the proposed unit section, pole and zero can be assigned independently. By using the unit ARCPFs, a very wideband image rejection filter can be realized by cascading the sections, which can greatly reduce the element value spread. To realize this, CMOS inverter based fully differential OTA which can operate under low supply voltage is also presented. This paper describes a six-stage active RC polyphase filter with 1-100 MHz passband in 0.18 µm CMOS technology.

Based on cyclic difference sets, sequences with two-valued autocorrelation can be constructed. Using these constructed sequences, two classes of binary constant weight codes are presented. Some codes proposed in this paper are proven to be optimal.

We present IND-ID-CPA secure identity-based encryption (IBE) schemes with tight reductions to the bilinear Diffie-Hellman (BDH) problem. Since the methods for obtaining IND-ID-CCA secure schemes from IND-ID-CPA secure schemes with tight reductions are already known, we can consequently obtain IND-ID-CCA secure schemes with tight reductions to the BDH problem. Our constructions are based on IBE schemes with tight reductions to the list bilinear Diffie-Hellman (LBDH) problem, and the schemes are converted to those with tight reductions to the BDH problem. Interestingly, it can be shown that there exists a black box construction, in which the former IBE schemes are given as black boxes. Our constructions are very simple and reasonably efficient.