In IP-based mobile networks, a few of mobility agents (e.g., home agent, foreign agent, etc.) are used for mobility management. Recently, Hierarchical Mobile IPv6 (HMIPv6) was proposed to reduce signaling overhead and handoff latency occurred in Mobile IPv6. In HMIPv6, a new mobility agent, called mobility anchor point (MAP), is deployed in order to handle binding update procedures locally. However, the MAP can be a single point of performance bottleneck when there are a lot of mobile node (MNs) performing frequent local movements. This is because the MAP takes binding update procedures as well as data packet tunneling. Therefore, it is required to control the number of MNs serviced by a single MAP. In this paper, we propose a load control scheme at the MAP utilizing an admission control algorithm. We name the proposed load control scheme proactive load control scheme to distinct from the existing load control schemes in cellular networks. In terms of admission control, we use the cutoff priority scheme. We develop Markov chain models for the proactive load control scheme and evaluate the ongoing MN dropping and the new MN blocking probabilities. As a result, the proactive load control scheme can reduce the ongoing MN dropping probability while keeping the new MN blocking probability to a reasonable level.

Checking the equivalence of two Boolean functions under permutation of the variables is an important problem in the synthesis of multiplexer-based field-programmable gate arrays (FPGAs), and the problem is known as Boolean matching. This paper presents an efficient breadth-first search technique for computing a canonical form--namely P-representative--of Boolean functions under permutation of the variables. Two functions match if they have the same P-representative. On an ordinary workstation, on the average, the method requires several microseconds to check the Boolean matching of functions with up to eight variables against a library with tens of thousands of cells.

A digitally controlled dc-dc power converter is useful to dc power supply systems for telecommunications and data communications systems that require high reliability and high performance. This paper presents a design criterion and output characteristics of 1 MHz high-speed digitally controlled dc-dc converter using a voltage controlled oscillator (VCO) as an analog to digital signal converter in the digital control circuit. As a result, it is revealed theoretically and experimentally that the proposed 1 MHz high-speed digitally controlled dc-dc converter has excellent static and dynamic characteristics. The adjustability of output voltage is less than 10 mV and there is no steady-state error within the integral controlled regulation range. Also, the overshoot is suppressed enough within 0.1 V and the transient time is very short.

Public telephone network have been dramatically changing to IP (Internet Protocol) based network. This paper starts with an overview of the present status of the telecommunications network and the rapid evolution of iDCs (internet Data Centers) now underway. Next, we focus on the existing configurations and the characteristics of power systems for IP equipment and iDCs, and then clarify the cutting-edge technologies for highly reliable powering systems and the advantages of DC power systems. Finally, the paper demonstrates energy-saving activities, and the prospected issues to be solved in the field of power systems for the coming full-fledged IT Age.

A simple, novel and low cost optical device with the possibility of being integrated into a network of wireless sensors has been developed for the colorimetric detection of iron (II). The proposed device used is based on two light emitting diodes (LEDs) configured so that one acts as an emitter and the other as a light detector, and a simple threshold detection/timer circuit to measure the photocurrent at the detector LED. The colorimetric reaction is based on the chelating reaction of divalent iron with the ligand 1,10-phenanthroline. The calibration graph shows that the detection limit (DL) of iron (II) using this approach is 5 ppb with a RSD of 0.08%. All experiments were carried out in triplicate (N = 3). The effect of some cations on the determination of Fe (II) using the proposed method was also studied. Results found showed that the system is relatively free from interferences.

Liquid-crystal devices with in-plane switching electrodes (IPS-LCD) are superior to twisted nematic ones in their wider range of viewing angle, but show serious color shift with viewing angle. The color shift is a phenomenon governed by the three-dimensional orientation of liquid-crystal molecules. In order to evaluate such effects numerically, light wave propagation in the IPS-LCD is studied using a two-dimensional finite-difference time-domain method, where all six components of electromagnetic field are analysed and the three-dimensional properties of liquid-crystal materials are taken into account through the dielectric tensor. The computational space termination is provided by a combination of the uniaxial perfectly matched layer and periodic boundary conditions. It is found for the first time numerically that the color shift effects strongly depend on the asymmetrical profile of liquid-crystal orientation, which is originated from the small pretilt angle.

The growth of the Internet has resulted in an increasing need for personalized information systems. The paper describes an autonomous agent, the Web Robot Agent or WebBot, which integrates with the web and acts as a personal recommendation system that cooperates with the user in order to identify interesting pages. The Apriori algorithm extracts the characteristics of the web pages in the form of association words that are semantically related and mines a bag of association words. Using hybrid components from collaborative filtering and content-based filtering, this hybrid recommendation system can overcome the shortcomings associated with traditional recommendation systems. In this paper, we present an improved recommendation system, which uses the user preference mining through hybrid 2-way filtering. The proposed method was tested on a database, and its effectiveness compared with existent methods was proven in on-line experiments.

Digital halftoning is used to quantize a grayscale image to a binary image. Error diffusion halftoning generates a high-quality binary image, but also generates some defects such as the warm effect, sharpening, and so forth. To reduce these defects, Kite proposed a modified threshold modulation method that utilizes a multiplicative parameter for controlling sharpening. Nevertheless, some degradation was observed near the edges of objects with a large luminance change. In this paper, we propose a method of controlling the multiplicative parameter in proportion to the magnitude of the local edge slope. The results of computer simulation show a greater reduction of sharpening in the halftone image. In particular, there is a great improvement in the quality of the edges of objects with a large luminance change.

In this letter, we propose an approach to incorporate a statistical model for the voiced/unvoiced (V/UV) speech decision under background noise environments. Our approach consists of splitting the input noisy speech into two separate bands and applying a statistical model for each band. We compute and compare the likelihood ratio (LR) for each band based on the statistical model and estimated noise statistics for the V/UV decision. According to the simulation test, the proposed V/UV decision shows a better performance compared with the selectable mode vocoder (SMV) V/UV decision algorithm, particularly in clean and white noise environments.

In this paper, we propose a probabilistic feature-based parsing model for head-final languages, which can lead to an improvement of syntactic disambiguation while reducing the parsing cost related to lexical information. For effective syntactic disambiguation, the proposed parsing model utilizes several useful features such as a syntactic label feature, a content feature, a functional feature, and a size feature. Moreover, it is designed to be suitable for representing word order variation of non-head words in head-final languages. Experimental results show that the proposed parsing model performs better than previous lexicalized parsing models, although it has much less dependence on lexical information.

Currently, multi-party video conference does not provide equivalent quality in comparison to face-to-face conference. One assumed reason is that participants cannot be aware of "who is focusing on whom". We introduce virtual space to a multi-party conference system, allocating avatars in a space. We also introduce intuitive input interface using motion processor in order to construct a multi-party conference system, which the user can use without being aware of it. A new displaying method is essential for this system, and we introduce a way by which a user can obtain the feedback of which user he/she is focusing on. We introduce e-MulCS as the system that fulfils these proposals. By comparing this system with the video conference system, the results show that our system supports the intuitive multi-party communication better.

This paper presents a method for improving the performance of syntactic analysis by using accurate temporal expression processing. Temporal expression causes parsing errors due to its syntactic duality, but its resolution is not trivial since the syntactic role of temporal expression is understandable in the context. In our work, syntactic functions of temporal words are decisively identified based on local contexts of individual temporal words acquired from a large corpus, which are represented by a finite state method. Experimental results show how the proposed method, incorporated with parsing, improves the accuracy and efficiency of the syntactic analysis.

Ultrafast all-optical switching was experimentally demonstrated using four-wave mixing in an SOA. Two pump pulses with different wavelengths and timings were used for 12 switching. The cross-correlation measurements of FWM signals using a short reference pulse show the high-speed switching capability for wavelength routing in OTDM networks.

This paper describes an approach to feature extraction in speech recognition systems using kernel principal component analysis (KPCA). This approach represents speech features as the projection of the mel-cepstral coefficients mapped into a feature space via a non-linear mapping onto the principal components. The non-linear mapping is implicitly performed using the kernel-trick, which is a useful way of not mapping the input space into a feature space explicitly, making this mapping computationally feasible. It is shown that the application of dynamic (Δ) and acceleration (ΔΔ) coefficients, before and/or after the KPCA feature extraction procedure, is essential in order to obtain higher classification performance. Better results were obtained by using this approach when compared to the standard technique.

Loss compensation in a RF CMOS active inductor with using a capacitor is proposed. This simple compensation technique yields a negative conductance characteristic that can compensate for the constant internal loss of active devices. Simulation results show that the inductor obtains a maximum Q-value of 1.2E8, an inductance value in the range of 50 nH to 450 nH, and a 1.4E-6 Ω of minimum total equivalent loss in the range of 0.6 GHz to 1.3 GHz.

This paper focuses on the processing of carbon nanotubes (CNTs) alignment as molecular bridge. A magnitude of an alternative voltage of about 1 V with 1 MHz was applied between two electrodes containing CNTs in suspension. The CNT bundles were well stretched along the field line distribution. Two kinds of directions could be distinguished around the electrode: the parallel and the Gaussian. On the other hand, different lengths of CNT bundles were aligned from one electrode side to the other. Those which were more than 1 µm reached both sides of electrodes while the short one did not but followed the Gaussian distribution of electric field. The short CNTs represent an increasing interest of study as far as their flexibility, mechanical and electrical properties are concerned. That's basically because one of their sides ended on the substrate. Among the advantages of the alignment of the CNT is to control the current flux and the thermal conductivity in composite resins or as new materials for the development of novel single-molecular transistors.

This paper proposes a post-layout transistor sizing method for crosstalk noise reduction. The proposed method downsizes the drivers of aggressor wires for noise reduction, utilizing the precise interconnect information extracted from the detail-routed layouts. We develop a transistor sizing algorithm for crosstalk noise reduction under delay constraints, and construct a crosstalk noise optimization method utilizing an analytic crosstalk noise model and a transistor sizing framework that have been developed. Our method exploits the transistor sizing framework that can vary transistor widths inside cells with interconnects unchanged. Our optimization method therefore never causes a new crosstalk noise problem, and does not need iterative layout optimization. The effectiveness of the proposed method is experimentally examined using 2 circuits. The maximum noise voltage is reduced by more than 50% without delay violation. These results show that the risk of crosstalk noise problems can be considerably reduced after detail-routing.

In this paper, a novel digitally-controlled varactor (DCV) for portable delay cell design is presented. The proposed varactor uses the gate capacitance differences of NAND/NOR gates under different digital control inputs to build up a digitally-controlled varactor. Then the proposed varactor is applied to design a high resolution delay cell and to achieve a fine delay resolution. Different types of NAND/NOR gates (2-input or 3-input) for DCV design are also investigated in this paper. The proposed DCV can be implemented with standard cells, thus it can be easily ported to different processes in a short time. A test chip fabricated on a standard 0.35 µm CMOS 2P4M process proves that the proposed delay cell has a fine delay resolution about 1.55 ps. As a result, the proposed DCV exhibits finer resolution, better linearity, and better portability than traditional delay elements, and is very suitable for portable delay cell design.

A large memory is typically designed with multiple identical memory blocks for reducing delay and power. The circuit verification of individual memory blocks can be effectively handled by the Symbolic Trajectory Evaluation (STE) approach. However, if multiple memory blocks are integrated into a single system, the STE approach cannot verify it economically. This paper introduces algorithms for verifying block-level connectivity of memories. The verification time of a large memory can be reduced drastically by using bottom-up verification scheme. That is, a memory block is first verified thoroughly, and then only the interconnection between memory blocks of the large memory needs to be verified. The proposed verification algorithms require (3n+2(log2n+1)+3log2m) Read/Write operations for a 2nm-bit memory, where n and m are the address width and data width, respectively. Also, the algorithms can verify 100% of the inter-port and intra-port signal misplaced faults of the address, data input, and data output ports.

This paper presents a fuzzy model-based approach for synchronization of time-delay chaotic system with input saturation. Time-delay chaotic drive and response system is respectively represented by Takagi-Sugeno (T-S) fuzzy model. Specially, the response system contains input saturation. Using the unidirectional linear error feedback and the parallel distributed compensation (PDC) scheme, we design fuzzy chaotic synchronization system and analyze local stability for synchronization error dynamics. Since time-delay in the transmission channel always exists, we also take it into consideration. The sufficient condition for the local stability of the fuzzy synchronization system with input saturation and channel time-delay is derived by applying Lyapunov-Krasovskii theory and solving linear matrix inequalities (LMI's) problem. Numerical examples are given to demonstrate the validity of the proposed approach.