This study is aimed at clarifying the mechanism of wear process for Ag plating. The samples of different hardness Ag plating on copper alloys were prepared as coupon and embossment specimens, which simulated terminal contacts. During the sliding test, the contact resistance and the friction coefficient versus sliding distance are measured. The surface observation and surface roughness of the Ag films after wear tests were investigated. As results, the hard Ag plating film (120 Hv) exhibited higher contact resistance comparing to the soft Ag plating film (80 Hv). The soft Ag film delivered wider wear trace on coupon specimens compared to the hard one. Moreover, the observation of tribofilms formed on the Ag films after wear tests suggested that a mixed-type of adhesive and abrasive wears occurred for both of soft and hard Ag films. Furthermore, the fretting corrosion resistance of Ag plating samples with different hardness was also investigated. As results, the wear resistance of hard Ag film was stronger than that of soft Ag film.

From past experience of the large-scale cutoff of existing networks as a result of the East Japan Great Earthquake and tsunamis, and from previous research on stabilizing ad hoc networks that lack control mechanisms, we have strengthened the resilience of NerveNet. NerveNet was originally designed and developed as an access network for providing context-aware services with the use of sensors and actuators. Thus, at present, it has the capability to enable resilient information sharing and communications in a region even if access to the Internet is impossible in emergency situations. NerveNet is composed of single or multiple base stations interconnected by a variety of Ethernet-based wired or wireless transmission systems. A network is formed using line, star, tree, or mesh topology. Network and data management works in each base station in a distributed manner, resulting in the resilience of this system. In collaboration with the town of Shirahama in Wakayama prefecture in Japan, we have been conducting a pilot test with the NerveNet testbed. The test includes nine base stations interconnected by 5.6-GHz Wi-Fi and Fixed Wireless Access (FWA), providing tourists and residents with Internet access. In the future, we expect that not only NerveNet but also other novel technologies will contribute to solving social problems and enriching people's lives.

In ProvSec 2014, Wang and Tanaka proposed a transformation which converts weakly existentially unforgeable (wEUF) signature schemes into strongly existentially unforgeable (sEUF) ones in the bounded leakage model. To obtain the construction, they combined leakage resilient (LR) chameleon hash functions with the Generalised Boneh-Shen-Waters (GBSW) transformation proposed by Steinfeld, Pieprzyk, and Wang. However, their transformation cannot be used in a more realistic model called continual leakage model since secret keys of LR chameleon hash functions cannot be updated. In this paper, we propose a transformation which can convert wEUF signature schemes into sEUF ones in the continual leakage model. To achieve our goal, we give a new definition of continuous leakage resilient (CLR) chameleon hash function and construct it based on the CLR signature scheme proposed by Malkin, Teranishi, Vahlis, and Yung. Although our CLR chameleon hash functions satisfy the property of strong collision-resistance, due to the existence of the updating algorithm, an adversary may find the kind of collisions such that messages are the same but randomizers are different. Hence, we cannot combine our chameleon hash functions with the GBSW transformation directly, or the sEUF security of the transformed signature schemes cannot be achieved. To solve this problem, we improve the original GBSW transformation by making use of the Groth-Sahai proof system and then combine it with CLR chameleon hash functions.

The development of multi-view video has paved the way for emerging 3D applications. In general multi-view video streaming, video frames for all viewpoints, i.e., cameras, must be transmitted to viewers because the view-switching demands of all viewers are unpredictable. However, existing transmission schemes are highly vulnerable to frame loss. Specifically, frame loss in one viewpoint can induce a collapse in decoding for other viewpoints. To improve loss-resilience, this paper proposes a multi-path based multi-view video transmission scheme. Our scheme encodes video frames into multiple versions that are independent of each other, using inter-view prediction. The scheme then transmits each version using multiple transmission paths. Our scheme makes three contributions: 1) it reduces video traffic even for a large number of cameras, 2) it prevents an increase in the number of undecoded video frames caused by single-frame loss, and 3) it conceals frame loss by taking video frames from other paths. Evaluations show that our proposed scheme improves video quality by 3 dB, as compared to existing transmission schemes in loss-prone environments.

Silicon-on-insulator (SOI) has become one of the most famous materials in recent years, especially in silicon photonics applications. This paper presents a comparative performance of a SOI-based optical interconnect (OI) vs. an electrical interconnect (EI) for high-speed performances at a circuit level. The SOI-based optical waveguide was designed using OptiBPM to obtain a single mode condition (SMC). Then, the optical interconnect (OI) link was simulated in OptiSPICE and was tested as an interconnection in two-stage CS amplifiers. The results showed that the two-stage CS amplifier using OI offered several advantages in terms of electrical performances, such as voltage gain, frequency bandwidth, slew rate, and propagation delay, which makes it superior to the EI.

The electron retention characteristics of memory capacitors with blocking oxide-silicon carbonitride (SiCN)-tunnel oxide stacked films were investigated for application in embedded charge trapping nonvolatile memories (NVMs). Long-term data retention in the SiCN memory capacitors was estimated to be more than 10 years at 85 °C. We presented an improved method to analyze the energy distribution of electron trap states numerically. Using the presented analytical method, electron trap states in the SiCN film were revealed to be distributed from 0.8 to 1.3 eV below the conduction band edge in the SiCN band gap. The presence of energetically deep trap states leads us to suggest that the SiCN dielectric films can be employed as the charge trapping film of embedded NVMs.

In this paper, we have investigated the characteristics of PdYb-silicide layer formed by the silicidation of Pd/Yb/n-Si(100) stacked structures for the first time. Pd (12-20 nm)/Yb (0-8 nm) stacked layers were deposited on n-Si(100) substrates by the RF magnetron sputtering at room temperature. Then, 10 nm-thick HfN encapsulating layer was deposited at room temperature. Next, silicidation was carried out by the RTA at 500°C/1 min in N2 followed by the selective etching. From the J-V characteristics of fabricated Schottky diode, Schottky barrier height (SBH) for electron was reduced from 0.73 eV of Pd2Si to 0.4 eV of PdYb-silicide in case the Pd/Yb thicknesses were 14/6 nm, respectively.

In this paper, Epitaxial (Epi) Junction Termination Extension (JTE) technique for silicon carbide (SiC) power device is presented. Unlike conventional JTE, the Epi-JTE doesn't require high temperature (about 500°C) implantation process. Thus, it doesn't require high temperature (about 1700°C) process for implanted dose activation and surface defect curing. Therefore, the manufacturing cost will be decreased. Also, the fabrication process is very simple because the dose of the JTE is controlled by epitaxy growth. The blocking characteristic is analyzed through 2D-simulation for the proposed Epi-JTE. In addition, the effect was validated by experiment of fabricated SiC device with the Single-Zone-Epi-JTE. As a result, it has blocking capability of 79.4% compared to ideal parallel-plane junction breakdown.

With the scaling of technology, nanoscale CMOS integrated circuits are becoming more sensitive to single event double node upsets induced by charge sharing. A novel highly robust hardened latch design is presented that is fully resilient to single event double node upsets and single node upsets. The proposed latch employs multiple redundant C-elements to form a dual interlocked structure in which the redundant C-elements can bring the affected nodes back to the correct states regardless of the energy of the striking particle. Detailed HSPICE results confirm that the proposed latch features complete resilience to double node upsets and achieves an improved trade-off in terms of robustness, area, delay and power in comparison with previous latches. Extensive Monte Carlo simulations validate the proposed latch features as less sensitive to process, supply voltage and temperature variations.

Video quality generally suffers from packet losses caused by an unreliable channel when video is transmitted over an error-prone wireless channel. This quality degradation is the main reason that a video compression encoder uses error-resilient coding to deal with the high packet-loss probability. The use of adequate error resilience can mitigate the effects of channel errors, but the coding efficiency for bit reduction will be decreased. On the other hand, H.264/AVC uses multiple reference frame (MRF) motion compensation for a higher coding efficiency. However, an increase in the number of reference frames in the H.264/AVC encoder has been recently observed, making the received video quality worse in the presence of transmission errors if the cyclic intra-refresh is used as the error-resilience method. This is because the reference-block selection in the MRF chooses blocks on the basis of the rate distortion optimization, irrespective of the intra-refresh coding. In this paper, a new error-resilient reference selection method is proposed to provide error resilience for MRF based motion compensation. The proposed error-resilient reference selection method achieves an average PSNR enhancement up to 0.5 to 2dB in 10% packet-loss-ratio environments. Therefore, the proposed method can be valuable in most MRF-based interactive video encoding system, which can be used for video broadcasting and mobile video conferencing over an erroneous network.

Multi-view video streaming plays an important role in new interactive and augmented video applications such as telepresence, remote surgery, and entertainment. For those applications, interactive multi-view video transmission schemes have been proposed that aim to reduce the amount of video traffic. Specifically, these schemes only encode and transmit video frames, which are potentially displayed by users, based on periodical feedback from the users. However, existing schemes are vulnerable to frame loss, which often occurs during transmissions, because they encode most video frames using inter prediction and inter-view prediction to reduce traffic. Frame losses induce significant quality degradation due to the collapse of the decoding operations. To improve the loss resilience, we propose an encoding/decoding system, Frame Popularity-based Multi-view Video Streaming (FP-MVS), for interactive multi-view video streaming services. The main idea of FP-MVS is to assign intra (I) frames in the prediction structure for less/more popular (i.e., few/many observed users) potential frames in order to mitigate the impact of a frame loss. In addition, FP-MVS utilizes overlapping and non-overlapping areas between all user's potential frames to prevent redundant video transmission. Although each intra-frame has a large data size, the video traffic can be reduced within a network constraint by combining multicast and unicast for overlapping and non-overlapping area transmissions. Evaluations using Joint Multi-view Video Coding (JMVC) demonstrated that FP-MVS achieves higher video quality even in loss-prone environments. For example, our scheme improves video quality by 11.81dB compared to the standard multi-view video encoding schemes at the loss rate of 5%.

Recent research has shown that the class of rotation symmetric Boolean functions is beneficial to cryptographics. In this paper, for an odd prime p, two sufficient conditions for p-variable rotation symmetric Boolean functions to be 1-resilient are obtained, and then several concrete constructions satisfying the conditions are presented. This is the first time that resilient rotation symmetric Boolean functions have been systematically constructed. In particular, we construct a class of 2-resilient rotation symmetric Boolean functions when p=2m+1 for m ≥ 4. Moreover, several classes of 1-order correlation immune rotation symmetric Boolean functions are also got.

A statistical call admission control (CAC) allows more calls with on-off patterns to be accepted and a higher channel efficiency to be achieved. In this paper, we propose three statistical CACs for VoIP calls with silence suppression considering the priority of each VoIP call, where the call priority is determined by the call acceptance order in an IP-PBX. We analyse the packet loss rates in an IP-PBX under the proposed strategies and express the end-to-end QoS of a VoIP call as an R-factor in a VoIP service network. The performances of the proposed CACs are evaluated using the maximum allowable number of VoIP calls while satisfying the end-to-end QoS constraint, the average QoS of acceptable VoIP calls and the channel efficiency. The advantage of the proposed statistical CACs over the non-statistical CAC is verified in terms of these three performance metrics. The results indicate that a trade-off is possible in that the maximum allowable number of VoIP calls in an IP-PBX increases as the average QoS of acceptable VoIP calls is lowered according to the proposed statistical CAC used. Nevertheless, the results allow us to verify that the channel efficiencies are the same for all the statistical CACs considered.

We have developed membrane distributed Bragg reflector (DBR) lasers on thermally oxidized Si substrate (SiO2/Si substrate) to evaluate the parameters of the on-Si lasers we have been developing. The lasers have InGaAsP-based multi-quantum wells (MQWs) grown on InP substrate. We used direct bonding to transfer this active epitaxial layer to SiO2/Si substrate, followed by epitaxial growth of InP to fabricate a buried-heterostructure (BH) on Si. The lateral p-i-n structure was formed by thermal diffusion of Zn and ion implantation of Si. For the purpose of evaluating laser parameters such as internal quantum efficiency and internal loss, we fabricated long-cavity lasers that have 200- to 600-µm-long active regions. The fabricated DBR lasers exhibit threshold currents of 1.7, 2.1, 2.8, and 3.7mA for active-region lengths of 200, 300, 400, and 600µm, respectively. The differential quantum efficiency also depends on active-region length. In addition, the laser characteristics depend on the distance between active region and p-doped region. We evaluated the internal loss to be 10.2cm-1 and internal quantum efficiency to be 32.4% with appropriate doping profile.

We prepared alumina passivation films for p-type silicon substrates by sol-gel wet process mainly using aluminum isopropoxide (Al(O-i-Pr)3) as a precursor material. The precursor solution was spin-coated onto p-type silicon substrates and then calcined for 1 hour in air. Minority carrier lifetime of the passivated wafers was evaluated for different calcination temperature conditions. We also compared the passivation quality of the alumina passivation films using different alumina precursor, aluminum acetylacetonate (Al(acac)3). Obtained effective minority carrier lifetime indicated that the lifetime is strongly depends on the calcination temperature. The substrate calcined below 400°C shows relatively short lifetime below 100 µsec. On the other hand, the substrate calcined around 500°C to 600°C indicates lifetime from 250 to 300 µsec. Calcination temperature dependence of the lifetime for the samples using Al(O-i-Pr)3 precursors shows almost the same as that using Al(acac)3.

After the East Japan great earthquake on March 11, 2011, many Japanese coastal resident areas were isolated from other because of destruction of information infrastructure, disconnection of communication network and excessive traffic congestion. The undelivered disaster information influenced the speed of evacuation, rescue of injured residents, and sending life-support materials to evacuation shelters. From the experience of such disaster, more robust and resilient networks are strongly required, particularly for preparation of large scale disasters. In this paper, in order to respond to those problems, we introduce Delay Tolerant Network (DTN) for disaster information transmission application in challenged network environment. Message delivery by transport vehicles such as cars between disaster-response headquarter and evacuation shelters in challenged network environment is considered. A improved message delivery method combined with DTN protocols and cognitive wireless network is explained. The computer simulation for the actual rural area in Japan is made to evaluate the performance and effectiveness of proposed method.

Audio hashing has been successfully employed for protection, management, and indexing of digital music archives. For a reliable audio hashing system, improving hash matching accuracy is crucial. In this paper, we try to improve a binary audio hash matching performance by utilizing auxiliary information, resilience mask, which is obtained while constructing hash DB. The resilience mask contains reliability information of each hash bit. We propose a new type of resilience mask by considering spectrum scaling and additive noise distortions. Experimental results show that the proposed resilience mask is effective in improving hash matching performance.

We fabricated silicon solar cells with spin-coated sol-gel alumina passivation layers on the rear side. Spin-coated alumina passivation films have moderate passivation quality and are inferior to atomic layer deposited passivation films. However, low-cost and low temperature process of the sol-gel deposition is still beneficial for the cells using commercially available Cz silicon wafers. Thus, we consider an applicability of the spin-coated alumina passivation layer for rear side passivation. Dependence of cell efficiency on contact spacing and contact diameter of a rear electrode was investigated by both experiments and numerical calculation. The experimental results indicated that conversion efficiency of the cell is enhanced from 9.1% to 11.1% by optimizing an aperture ratio and contact spacing of the rear passivation layers. Numerical calculation indicated that small contact diameter with low aperture ratio of a rear passivation layer is preferable to achieve good cell performance in our experimental condition. We confirmed the effectivity of the spin-coated alumina passivation films for rear surface passivation of the low-cost silicon solar cells.

Many studies have applied the three-dimensional discrete wavelet transform (3D DWT) to video coding. It is known that corruptions of the lowest frequency sub-band (LL) coefficients of 3D DWT severely affect the visual quality of video. Recently, we proposed an error resilient 3D DWT video coding method (the conventional method) that employs dispersive grouping and an error concealment (EC). The EC scheme of our conventional method adopts a replacement technique of the lost LL coefficients. In this paper, we propose a new 3D DWT video transmission method in order to enhance error resilience. The proposed method adopts an error correction scheme using invertible codes to protect LL coefficients. We use half-rate Reed-Solomon (RS) codes as invertible codes. Additionally, to improve performance by using the effect of interleave, we adopt a new configuration scheme at the RS encoding stage. The evaluation by computer simulation compares the performance of the proposed method with that of other EC methods, and indicates the advantage of the proposed method.

Peer-to-peer (P2P) networks have attracted increasing attention in the distribution of large-volume and frequently accessed content. In this paper, we mainly consider the problem of key leakage in secure P2P content distribution. In secure content distribution, content is encrypted so that only legitimate users can access the content. Usually, users (peers) cannot be fully trusted in a P2P network because malicious ones might leak their decryption keys. If the redistribution of decryption keys occurs, copyright holders may incur great losses caused by free riders who access content without purchasing it. To decrease the damage caused by the key leakage, the individualization of encrypted content is necessary. The individualization means that a different (set of) decryption key(s) is required for each user to access content. In this paper, we propose a P2P content distribution scheme resilient to the key leakage that achieves the individualization of encrypted content. We show the feasibility of our scheme by conducting a large-scale P2P experiment in a real network.