This paper proposes spread-spectrum clock modulation algorithms for EMI reduction in digitally-controlled DC-DC converters. In switching regulators using PWM, switching noise and harmonic noise concentrated in a narrow spectrum around the switching frequency can cause severe EMI. Spread-spectrum clock modulation can be used to minimize EMI. In conventional switching regulators using analog control it is very difficult to realize complex spread-spectrum clocking, however this paper shows that it is relatively easy to implement spread-spectrum EMI-reduction using digital control. The proposed algorithm was verified using a power converter simulator (SCAT).

The recognition performance of the conventional 3D face recognition algorithm using ICP (Iterative Closest Point) is degraded for the 3D face data with expression changes. Addressing this problem, we consider the use of the expression-invariant local regions of a face. We find the expression-invariant regions through the distance analysis between 3D face data with the neutral expression and smile, and propose a robust 3D face recognition algorithm using passive stereo vision. We demonstrate efficient recognition performance of the proposed algorithm compared with the conventional ICP-based algorithm through the experiment using a stereo face image database which includes the face images with expression changes.

In this article, we introduce a new concept for the future information environment, called an "ambient information environment (AmIE)." We first explain it, especially emphasizing the difference from the existing ubiquitous information environment (UbIE), which is an interaction between users and environments. Then, we focus on an ambient networking environment (AmNE) which supports the AmIE as a networking infrastructure. Our approach of a biologically inspired framework is next described in order to demonstrate why such an approach is necessary in the AmIE. Finally, we show some example for building the AmNE.

The problem of analyzing transient in transmission line circuits is studied with emphasis on obtaining the transient voltage and current distributions. A new method for solving Telegrapher equation that characterizes the uniform transmission lines is presented. It not only gives the time domain solution of the line terminal voltage and current, but also their distributions within the lines. The method achieves its goal by treating the voltage and current distributions as distributed state variables and transforms the Telegrapher equation into an ordinary differential equation. This allows the coupled transmission lines to be treated as a single component that behaves like other lumped dynamic components, such as capacitors and inductors. Using Backward Differentiation Formulae for time discretization, the transmission line component is converted to its time domain companion model, from which its local truncation error for time step control can be derived. As the shapes of the voltage and current distributions get more complicated with time, they can be approximated by piecewise exponential functions with controllable accuracy. A segmentation algorithm is thus devised so that the line is dynamically bisected to guarantee that the total piecewise exponential approximation error is only a small fraction of the local truncation error. Using this approach, the user can see the line voltage and current at any point and time freely without explicitly segment the line before starting the simulation.

A call admission control (CAC) scheme based on statistical information is proposed, called the statistical CAC scheme. A conventional scheme needs to manage session information for each link to update the residual bandwidth of a network in real time. This scheme has a scalability problem in terms of network size. The statistical CAC rejects session setup requests in accordance to a pre-computed ratio, called the rejection ratio. The rejection ratio is computed by using statistical information about the bandwidth requested for each link so that the congestion probability is less than an upper bound specified by a network operator. The statistical CAC is more scalable in terms of network size than the conventional scheme because it does not need to keep accommodated session state information. Numerical results show that the statistical CAC, even without exact session state information, only slightly degrades network utilization compared with the conventional scheme.

Privacy preserving is indispensable in data mining. In this paper, we present a novel clustering method for distributed multi-party data sets using orthogonal transformation and data randomization techniques. Our method can not only protect privacy in face of collusion, but also achieve a higher level of accuracy compared to the existing methods.

Accompanying with the popularization of portable equipments, and the rapid growth of the size of the electric systems, efficient low power design methodologies have been highly required. To satisfy these requests, a high accurate and high efficient power analysis in higher abstraction level is very important. The design environment is composed by efficient algorithms of power modeling, power library building, and data extracting. Those components of the environment should be balanced for the total efficiency and accuracy. We have proposed a new efficient power modeling environment which uses a look-up table (LUT). It reduces the size of the LUT drastically, compared to conventional algorithms. It makes the power analysis and library building high efficient. The experimental results show that our approach reduces the computation time to build the library to one tenth while keeping the accuracy of the power analysis. The RMS error and the largest error has been less than 8.30%, 59.16%, respectively.

In this paper, we propose a control method for the synchronization of chaotic systems that does not require the systems to be connected, unlike existing methods such as that proposed by Pecora and Carroll in 1990. The method is based on the reinforcement learning algorithm. We apply our method to two discrete-time chaotic systems with mismatched parameters and achieve M step delay synchronization. Moreover, we extend the proposed method to the synchronization of continuous-time chaotic systems.

In this study, a performance isolation mechanism based on a fuzzy control technique is developed in such a way that ambiguous situations caused when estimating the workload of cluster-based web servers, client request rates, and dynamic request rates can be represented effectively. The proposed mechanism involving a fuzzy-based technique is compared with a non-fuzzy technique in terms of the response time in the 95th percentile. Experiments showed that the proposed technique improves the performance of web servers that provide differentiated services.

Although wavelength division multiplexing-passive optical network (WDM-PON) is known as a high-speed transfer, it creates high channel costs per subscriber and low bandwidth utilization due to the fact that a wavelength is dedicated to each subscriber. Thus, it is imperative to reduce channel costs per subscriber and improve the bandwidth utilization. To achieve these, we first adopt a existing WDM-PON, which uses the bidirectional transmission with a single source for cost-efficiency by employing a gain-saturated reflective semiconductor optical amplifier (RSOA). Secondly, based on the existing WDM-PON, we propose an enhanced hybrid WDM/TDM-PON, which can extend the number of subscribers supported in each wavelength with splitters in the physical layer and a shared-time division duplex (TDD) frame format in the media access control (MAC) layer. Moreover, it can adaptively control the bandwidth through a dynamic bandwidth allocation (DBA) scheme according to the volume of traffic. Compared to the non TDD-based hybrid WDM/TDM-PON, it can reduce channel costs per subscriber from the extended number of subscribers supported in each wavelength. Furthermore, due to the DBA, it can improve the total queueing delay and throughput, and thus increase the bandwidth utilization.

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.

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.

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.

Low energy and high performance embedded processor is crucial in the future nomadic embedded systems design. Improvement of memory accesses, especially improvement of spatial and temporal locality is well known technique to reduce energy and increase performance. However, after transformations that improve locality, address calculation often becomes a bottleneck. In this paper, we propose novel AGU (Address Generation Unit) exploration and mapping technique based on a reconfigurable AGU model. Experimental results show that the proposed techniques help exploring AGU architectures effectively and designers can get trade-offs of real life applications for about 10 hours.

In this paper, an information distribution model based on human's behavior is proposed. We also propose dynamic parameters to make the model more practical for real life social network. Subsequently, the simulations are conducted based on the small-world network and its characteristics, and the parameters in the model are analyzed to increase efficiently the power of information distribution. Our study and simulation results show that the proposed model can be used to analyze and predict the effectiveness of information distribution. Moreover, the study also shows how to use the model parameters to increase power of the distribution.

Privacy remains an issue for IT services. Users are concerned that their history of service use may be traceable since each user is assigned a single identifier as a means of authentication. In this paper, we propose a perfectly anonymous attribute authentication scheme that is both unidentifiable and untraceable. Then, we present the evaluation results of a prototype system using a PC and mobile phone with the scheme. The proposed scheme employs a self-blindable certificate that a user can change randomly; thus the certificate is modified for each authentication, and the authentication scheme is unidentifiable and untraceable. Furthermore, our scheme can revoke self-blindable certificates without leaks of confidential private information and check the revocation status without online access.

A subdivision of a rectangle into rectangular faces with horizontal and vertical line segments is called a rectangular drawing or floorplan. It has been an open problem to determine whether there exist a polynomial time algorithm for computing R(n). We affirmatively solve the problem, that is, we introduce an O(n4)-time and O(n3)-space algorithm for R(n). The algorithm is based on a recurrence for R(n), which is the main result of the paper. We also implement our algorithm and computed R(n) for n 3000.

It is a very important and intriguing problem in digital image-processing to decompose an input image into intuitively convincible image-components such as a structure component and a texture component, which is an inherently nonlinear problem. Recently, several numerical schemes to solve the nonlinear image-decomposition problem have been proposed. The use of the nonlinear image-decomposition as a pre-process of several image-processing tasks will possibly pave the way to solve difficult problems posed by the classic approach of digital image-processing. Since the new image-processing approach via the nonlinear image-decomposition treats each separated component with a processing method suitable to it, the approach will successfully attain target items seemingly contrary to each other, for instance invisibility of ringing artifacts and sharpness of edges and textures, which have not attained simultaneously by the classic image-processing approach. This paper reviews quite recently developed state-of-the-art schemes of the nonlinear image-decomposition, and introduces some examples of the decomposition-and-processing approach.

A method is proposed for estimating code and carrier phase parameters of GNSS reflected signals in low SNR (signal-to-noise ratio) environments. Simulation results show that the multipath impact on code and carrier with 0.022 C/A chips delay can be estimated in 0 dB SNR in the condition of 46 MHz sampling rate.

In RFID systems, collision resolution is a significant issue in fast tag identification. This letter presents a dynamic frame-slotted ALOHA algorithm that uses a collision factor (DFSA-CF). This method enables fast tag identification by estimating the next frame size with the collision factor in the current frame. Simulation results show that the proposed method reduces slot times Required for RFID identification. When the number of tags is larger than the frame size, the efficiency of the proposed method is greater than those of conventional algorithms.