In this study, I have numerically investigated the temperature distribution of n-type Si Nano Wire MOS Transistor induced by the self-heating effect by using a 3-D device simulator. The dependencies of temperature distribution within the Si Nano Wire MOS Transistor on both its gate length and width of the Si nano wire were analyzed. First, it is shown that the peak temperature in Si Nano Wire MOS Transistor increases by 100 K with scaling the gate length from 54 nm to 14 nm in the case of a 50 nm width Si nano wire. Next, it is found that the increase of its peak temperature due to scaling the gate length can be suppressed by scaling the size of the Si nano wire, for the first time. The peak temperature suppresses by 160 K with scaling the Si nano wire width from 50 nm to 10 nm in the case of a gate length of 14 nm. Furthermore, the heat dissipation in the gate, drain, and source direction are analyzed, and the analytical theory of the suppression of the temperature inside Si Nano Wire MOSFET is proposed. This study shows very useful results for future Si Nano Wire MOS Transistor design for suppressing the self-heating effect.

Sensor networks have promising applications such as battlefield surveillance, biological detection, and emergency navigation, etc. Crucial problems in sensor networks are energy-efficiency and collision avoidance in wireless communication. To deal with the problems, we consider a self-stabilizing solution to the construction of k disjoint sense-sleep trees, where range adjustment and the use of GPS are allowed. Each root is determined by its identifier and is distinguished by its color, the identification of a tree. Using a dominating k-partition rule, each non-root node first determines a color irrelevant to the root. Then, the non-root node determines a parent node that is equally colored with minimal distance. If there is no appropriate parent, the range is extended or shrunk until the nearest parent is determined. Finally, we perform a simulation.

Arrayed waveguide grating (AWG) is a promising technology for constructing high-speed large-capacity WDM switches, because it can switch fast, is scalable to large size and consumes little power. To take the full advantage of high-speed AWG, the routing control of a massive AWG-based switch should be as simple as possible. In this paper, we focus on the self-routing design of AWG-based switches with O(1) constant routing complexity and propose a novel construction of self-routing AWG switches that can guarantee the attractive nonblocking property for both the wavelength-to-wavelength and wavelength-to-fiber request models. We also fully analyze the proposed design in terms of its blocking property, hardware cost and crosstalk performance and compare it against traditional designs. It is expected that the proposed construction will be useful for the design and all-optical implementation of future ultra high-speed optical packet/burst switches.

In a multi-hop mobile ad-hoc network, broadcasting is an elementary operation to support many applications. Broadcasting by flooding may cause serious redundancy, contention, and collision in the network, which is referred to as the broadcast storm problem. Many broadcasting schemes have been proposed to give better performance than simple flooding in mobile ad-hoc network. How to decide whether rebroadcast or not also poses a dilemma between reachability and efficiency under different host densities. In this paper, we propose an enhanced broadcasting scheme, which can reduce rebroadcast packets without loss of reachability. Simulation results show that the proposed scheme offers better reachability and efficiency than other previous schemes.

This paper presents an FPGA implementation of highly modular universal discrete transforms. The implementation relies upon the unified discrete Fourier Hartley transform (UDFHT), based on which essential sinusoidal transforms including discrete Fourier transform (DFT), discrete Hartley transform (DHT), discrete cosine transform (DCT) and discrete sine transform (DST) can be realized. It employs a reconfigurable, scalable and modular architecture that consists of a memory-based FFT processor equipped with pre- and post-processing units. Besides, a pipelining technique is exploited to seamlessly harmonize the operation between each sub-module. Experimental results based on Xilinx Virtex-II Pro are given to examine the performance of the proposed UDFHT implementation. Two practical applications are also shown to demonstrate the flexibility and modularity of the proposed work.

An on-chip power supply noise canceller with higher voltage supply and switching transistor is proposed and the effectiveness of the canceller is experimentally verified. The noise canceller is effective for nano-second order noise caused by circuit wakeup or step increase of frequency in frequency hopping. The principle of the noise canceller is to reduce the current flowing through the supply line of VDD by injecting additional current from the higher voltage supply, so that the voltage drop across the VDD supply line is reduced. As additional current flow from higher supply, switching transistor has to be turned off not to increase the power consumption. With turn-off time of 2L/R, this current can be turned off without inducting another droop due to the increase of current flowing through the power supply line. The measurement shows the canceller reduces 68% of the noise with load circuit equivalent to 530 k logic gates in 90-nm CMOS with 9% wire overhead, 1.5% area overhead, and 3% power overhead at 50 k wake-ups/s. Compared to passive noise reduction, proposed noise canceller reduces power supply noise by 64% without wire overhead and to achieve same noise reduction with passive method, 77 times more C or 45 times less L is required. Too large switching transistor results in saturated noise reduction effect and higher power consumption. A rule-of-thumb is to set the on-resistance to supply 100% of load current when turned-on.

Flooding is an indispensable operation for providing control or routing functionalities to mobile ad hoc networks (MANETs). Previously, many flooding schemes have been studied with the intention of curtailing the problems of severe redundancies, contention, and collisions in traditional implementations. A recent approach with relatively high efficiency is 1HI by Liu et al., which uses only 1-hop neighbor information. The scheme achieves local optimality in terms of the number of retransmission nodes with time complexity Θ(nlog n), where n is the number of neighbors of a node; however, this method tends to make many redundant transmissions. In this paper, we present a novel flooding algorithm, 2HBI (2-hop backward information), that efficiently reduces the number of retransmission nodes and solves the broadcast storm problem in ad hoc networks using our proposed concept, "2-hop backward information." The most significant feature of the proposed algorithm is that it does not require any extra communication overhead other than the exchange of 1-hop HELLO messages but maintains high deliverability. Comprehensive computer simulations show that the proposed scheme significantly reduces redundant transmissions in 1HI and in pure flooding, up to 38% and 91%, respectively; accordingly it alleviates contention and collisions in networks.

In static wireless ad hoc networks such as wireless mesh networks and wireless sensor networks, multipath routing techniques are very useful for improving end-to-end delay, throughput, and load balancing, as compared to single-path routing techniques. When determining multiple paths, however, multipath routing protocols should address the well-known route coupling problem that results from a geographic proximity of adjacent routes and that hampers performance gain. Although a lot of multipath routing protocols have been proposed, most of them focused on obtaining node or link-disjoint multipaths. In order to address the route coupling problem, some multipath routing protocols utilizing zone-disjointness property were proposed. However, they suffer from an overhead of control traffic or require additional equipment such as directional antenna. This paper therefore proposes a novel multipath routing protocol, based on geographical information with low overhead, called 3-directional zone-disjoint multipath routing protocol (3DMRP). 3DMRP searches up to three zone-disjoint paths by using two techniques: 1) greedy forwarding, and 2) RREP-overhearing. One primary and two secondary paths are obtained via greedy forwarding in order to reduce control overhead, and these secondary paths are found by avoiding the RREP overhearing zone created during the primary path acquisition. In particular, two versions of 3DMRP are introduced in order to avoid the RREQ-overhearing zone. Through ns-2 simulations, 3DMRP is evaluated to verify that it achieves performance improvements in terms of throughput and control overhead.

This paper describes a distinctive phonetic feature (DPF) extraction method for use in a phoneme recognition system; our method has a low computation cost. This method comprises three stages. The first stage uses two multilayer neural networks (MLNs): MLNLF-DPF, which maps continuous acoustic features, or local features (LFs), onto discrete DPF features, and MLNDyn, which constrains the DPF context at the phoneme boundaries. The second stage incorporates inhibition/enhancement (In/En) functionalities to discriminate whether the DPF dynamic patterns of trajectories are convex or concave, where convex patterns are enhanced and concave patterns are inhibited. The third stage decorrelates the DPF vectors using the Gram-Schmidt orthogonalization procedure before feeding them into a hidden Markov model (HMM)-based classifier. In an experiment on Japanese Newspaper Article Sentences (JNAS) utterances, the proposed feature extractor, which incorporates two MLNs and an In/En network, was found to provide a higher phoneme correct rate with fewer mixture components in the HMMs.

In this paper, a novel model of Gaussian pulse propagation in optical fiber is proposed to comprehensively analyze the impact of Group Velocity Dispersion (GVD) on the performance of two-dimensional wavelength hopping/time spreading optical code division multiple access (2-D WH/TS OCDMA) systems. In addition, many noise and interferences, including multiple access interference (MAI), optical beating interference (OBI), and receiver's noise are included in the analysis. Besides, we propose to use the heterodyne detection receiver so that the receiver's sensitivity can be improved. Analytical results show that, under the impact of GVD, the number of supportable users is extremely decreased and the maximum transmission length (i.e. the length at which BER 10-9 can be maintained) is remarkably shortened in the case of normal single mode fiber (ITU-T G.652) is used. The main factor that limits the system performance is time skewing. In addition, we show how the impact of GVD is relieved by dispersion-shifted fiber (ITU-T G.653). For example, a system with 321 Gbit/s users can achieve a maximum transmission length of 111 km when transmitted optical power per bit is -5 dBm.

Transient routing loops have been observed to form in Mobile Ad-hoc Networks running the OLSRv2 proactive link-state routing protocol. The packets falling into loops impact the surrounding network thus degrading throughput even though only a small proportion of the traffic may enter these loops and only for a short time. This becomes significantly more evident when Link Layer Notification is used to catch broken links, inadvertently leading to an increase in the number of loops. Two methods of Loop Detection are introduced and are used to trigger either Loop Suppression by selectively and preemptively discarding the looping packets that are unlikely to reach their destination, or Loop Correction by the notification of the routing protocol to cut the link over which the packet is looping. The newly introduced Loop Suppression and Loop Correction techniques used with Link Layer Notification are shown to significantly increase network performance over plain OLSRv2 and OLSRv2 with Link Layer Notification.

Recent research on overlay networks has revealed that user-perceived network performance, such as end-to-end delay performance, could be improved by an overlay routing mechanism. However, these studies consider only end-to-end delay, and few studies have focused on bandwidth-related information, such as available bandwidth and TCP throughput, which are important performance metrics especially for long-lived data transmission. In the present paper, we investigate the effect of overlay routing both delay and bandwidth-related information, based on the measurement results of network paths between PlanetLab nodes. We consider three metrics for selecting the overlay route: end-to-end delay, available bandwidth, and TCP throughput. We then show that the available bandwidth-based overlay routing provides significant gain, as compared with delay-based routing. We further reveal the correlation between the latency and available bandwidth of the overlay paths and propose several guidelines for selecting an overlay path.

With the growth of wireless computing and the popularity of eXtensible Markup Language (XML), wireless XML data management is emerging as an important research area. In this paper, cache invalidation methodology with XML update is addressed in wireless computing environments. A family of XML cache invalidation strategies, called S-XIR, D-XIR and E-XIR, is suggested. Using S-XIR and D-XIR, the unchanged part of XML data, only its structure changes, can be effectively reused in client caching. E-XIR, which uses prefetching, can further improve access time. Simulations are carried out to evaluate the proposed methodology; they show that the proposed strategies improve both tuning time and access time significantly. In particular, the proposed strategies are on average about 4 to 12 times better than the previous approach in terms of tuning time.

The goal of personal-style handwriting synthesis is to produce texts in the same style as an individual writer by analyzing the writer's samples of handwriting. The difficulty of handwriting synthesis is that the output should have the characteristics of the person's handwriting as well as looking natural, based on a limited number of available examples. We develop a synthesis algorithm which produces handwriting that exhibits naturalness based on the probabilistic character model.

The Transition Edge Sensor (TES)-Energy Dispersive Spectrometer (EDS) is an X-ray detector with high-energy resolution (12.8 eV). The TES can be mounted to a scanning electron microscope (SEM). The TES-EDS is based on a cryogen-free dilution refrigerator. The high-energy resolution enables analysis of the distribution of various elements in samples under low acceleration voltage (typically under 5 keV) by using K-lines of light elements and M lines of heavy elements. For example, the energy of the arsenic L line differs from the magnesium K line by 28 eV. When used to analyze the spore of the Pteris vittata L plant, the TES-EDS clearly reveals a different distribution of As and Mg in the micro region of the plant. The TES-EDS with SEM yields detailed information about the distribution of multi-elements in a sample.

By use of the shadow theory developed recently, this paper deals with the transverse electric (TE) wave diffraction by a perfectly conductive periodic array of rectangular grooves. A set of equations for scattering factors and mode factors are derived and solved numerically. In terms of the scattering factors, diffraction amplitudes and diffraction efficiencies are calculated and shown in figures. It is demonstrated that diffraction efficiencies become discontinuous at an incident wave number where the incident wave is switched from a propagating wave to an evanescent one, whereas scattering factors and diffraction amplitudes are continuous even at such an incident wave number.

This paper addresses the interference and load imbalance problems in multi-radio infrastructure mesh networks where each mesh node is equipped with multiple radio interfaces and a subset of nodes serve as Internet gateways. To provide backbone support, it is necessary to reduce interference and balance load in Wireless Mesh Networks (WMNs). In this paper, we propose a new Load-Aware Routing Metric, called LARM, which captures the differences in transmission rates, packet loss ratio, intra/inter-flow interference and traffic load in multi-radio mesh networks. This metric is incorporated into the proposed load-balancing routing, called LBM, to provide load balancing for multi-radio mesh network. Simulation results show that LARM provides better performance compared to WCETT and hop-count routing metrics in LBM routing protocol.

This paper proposes a scan design for delay fault testability of dual circuits. In normal operation mode, each proposed scan flip flop operates as a master-slave flip flop. In test mode, the proposed scan design performs scan operation using two scan paths, namely master scan path and slave scan path. The master scan path consists of master latches and the slave scan path consists of slave latches. In the proposed scan design, arbitrary two-patterns can be set to flip flops of dual circuits. Therefore, it achieves complete fault coverage for robust and non-robust testable delay fault testing. It requires no extra latch unlike enhanced scan design. Thus the area overhead is low. The evaluation shows the test application time of the proposed scan design is 58.0% of that of the enhanced scan design, and the area overhead of the proposed scan design is 13.0% lower than that of the enhanced scan design. In addition, in testing of single circuits, it achieves complete fault coverage of robust and non-robust testable delay fault testing. It requires smaller test data volume than the enhanced scan design in testing of single circuits.

In reliable multicast, feedback and recovery traffic limit the performance and scalability of the multicast session. In this paper, we present an improvement to the many-to-many reliable multicast protocol, Group-Aided Multicast protocol (GAM), with a local-group based recovery by making use of forward error correction (FEC) locally in addition to NACK/retransmission. In contrast to the original GAM, which only makes use of NACK-based recovery, our scheme produces FEC packets and multicasts the packets within the scope of a local group in order to correct uncorrelated errors of the local members in each group of the multicast session, which reduces the need for NACK/retransmission. By using our scheme, redundancy traffic can be localized in each group within a multicast session, and the overall recovery traffic can be reduced.

We report on the spurious suppression effect in low-microwave power transmitters by high temperature superconducting (HTS) bandpass filters (BPFs) which are promising for devices requiring BPFs with high-frequency selectivity. Some of the major issues on the power BPFs with HTS planar circuits for wireless communication applications are reviewed. As a case study for the HTS filter and its spurious suppression effect, this paper describes an example of the measured power spectrum density (PSD) on the suppression effect by one of our developed power BPFs with YBCO films for the 5 GHz band. It was designed with equivalent cascade resonators of 16 poles. We demonstrated the effect by HTS power filter in a power amplifier for the 5 GHz band.