Grouping multiple voice frames into a single IP packet ("frame grouping") is a commonly mentioned approach to saving bandwidth in IP telephony. But little is known as to when, how, and how much frame grouping should be done in Internet environment. This paper explores the feasibility and the methods of frame grouping based on Internet delay measurement. Specifically, we propose an adaptive frame grouping method that minimizes the delay violation while reducing the bandwidth usage by as much as a factor of two under real Internet delay fluctuations. The performance of the method is evaluated as it is used against a single voice stream and then against multiple voice streams.

We present a simple framework for multicasting video in an active network, in which we overcome heterogeneity in the quality requests by filtering the video stream at some properly located active nodes. The framework includes the requirements for the underlying active network and outlines the video multicast application. We then introduce a heuristic algorithm for electing the filtering nodes to conform a multicast distribution tree, in which we use an objective function to, for example, minimize the required bandwidth. We evaluate the performance of our algorithm comparing it with simulcast and layered encoded transmission through simulation experiments, showing some advantages of using active filtering.

We have developed a 200-channel imaging system that enables measurement of changes in oxygenation and blood volume and that covers a wider area (45 cm 15 cm) than that covered by conventional systems. This system consisted of 40 probes of five channels, a light-emitting diode (LED) driver, multiplexers and a personal computer. Each probe was cross-shaped and consisted of an LED, five photo diodes, and a current-to-voltage (I-V) converter. Lighting of the LEDs and acquisition of 200-channel data were time-multiplexed. The minimum data acquisition time for 200 channels, including the time required for calculation of oxygenation and monitoring of a few traces of oxygenation on a computer display, was about 0.2 s. We carried out exercise tests and measured the changes in oxy- and deoxy-hemoglobin concentrations in the thigh. Working muscles in exercises could be clearly imaged, and spatio-temporal changes in muscle oxygenation during exercise and recovery were also shown. These results demonstrated that the 200-channel imaging system enables observation of the distribution of muscle metabolism and localization of muscle function.

In order to navigate a mobile robot or an autonomous vehicle in indoor environment, which includes several kinds of obstacles such as walls, furniture, and humans, the distance between the mobile robot and the obstacles have to be determined. These obstacles can be considered as walls with complicated edges. This paper proposes a mobile-robot-navigation method by using the polar coordinate transformation from an omnidirectional image. The omnidirectional image is obtained from a hyperboloidal mirror, which has the prominent feature in sensing the surrounding image at the same time. When the wall image from the camera is transformed by the transformation, the straight lines between the wall and the floor appear in the curve line after transformation. The peak point represents the distance and the direction between the robot and the wall. In addition, the wall types can be classified by the pattern and number of peak points. They are one side wall, corridor and corner. To navigate the mobile robot, in this paper, it starts with comparing a peak point obtained from the real image with the reference point determined by designed distance and direction. If there is a difference between the two points, the system will compute appropriate wheel angle to adjust the distance and direction against the wall by keeping the peak point in the same position as the reference point. The experiments are performed on the prototype mobile robot. The results show that for the determining distance from the robot to the wall between 70-290 cm, the average error is 6.23 percent. For three types of the wall classification, this method can correctly classify 86.67 percent of 15 image samples. In the robot movement alongside the wall, the system approximately consumes the 3 frame/s processing time at 10 cm/s motion speed. The mobile robot can maintain its motion alongside the wall with the average error 12 cm from reference distance.

We applied control theory to nerve-muscle in order to model and systematize the muscle system. The association between nerve stimulation frequencies and electromyogram (EMG) amplitude was studied in rat nerve-muscle under normal and hypokalemic conditions. From these results, we modeled the nerve-muscle and simulated frequency response from the nerve-muscle system which can be expressed as a closed loop transfer function.

We have developed optical encoding devices for processing femtosecond pulses. These devices are based on spectral separation devices and light modulators with fiber gratings. Experiments were made to encode a light pulse in the spectral domain. These experiments utilize the characteristics that a femtosecond light pulse has a very broad spectrum. An input femtosecond light pulse is decomposed into a series of wavelength components. Each wavelength component with narrow spectra <1 nm width is successfully extracted into a single mode fiber. Light modulators corresponding to wavelength components are assigned to the 1st bit, the 2nd bit, the 3rd bit, , the nth bit, respectively. All of the encoded wavelength components are again recombined into a single time-varying signal and transmitted through an optical fiber. Decoding at receiving site is made by the reverse operation. Encoding and decoding for 2-bit and 4-bit signals were demonstrated for 200 fs input light pulse with about 40 nm spectral width.

This paper presents a method for detection of calcification, which is an important early sign of breast cancer in mammograms. Since information of calcifications is located in inhomogeneous background and noises, it is hard to be detected. This method uses wavelet packet transform (WPT) for elimination of the background image related to low frequency components. However, very high frequency signals of noises exist with the calcifications and make it hard to suppress them. Since calcification location can be represented as vertical, horizontal, and diagonal edges in time-frequency domain, the edges in spatial domain can be utilized as a filter for noise suppression. Then the image from inverse transform will contain only required information. A free-response operating characteristic (FROC) curve is used to evaluate a performance of proposed method by applying it to thirty images of calcifications. The results show 82.19 percent true positive detection rate at the cost of 6.73 false positive per image.

A new objective speech quality measure, Bark Coherence Function is presented. The Coherence Function was used for evaluating the non-linear distortion of low-to-medium rate speech coders. However, it is not well suited for quality estimation in modern speech transmission, especially, CDMA mobile communication system. In the proposed method, Coherence Function is newly defined in psycho-acoustic domain as the cognition module of perceptual speech quality measure and evaluates the perceptual non-linear distortion of mobile system. The experimental results showed that the proposed method has good performance over CDMA PCS and digital cellular system.

We propose a frequency stabilization system for laser diodes (LD's), in which the major parameters in the stabilization process can be controlled in respond to the monitored frequency noise characteristics in real-time basis. The performance of this system was also tested through stabilizing a 35 mW visible LD. The center frequency of the LD has been stabilized by negative electrical feedback based on Pound-Drever-Hall technique. The linewidth of the LD has been reduced by adapting optical feedback from resonant confocal Fabry-Perot (CFP) cavity. The controlling parameters, especially gain levels and frequency responses of the negative electrical feedback loop can be manipulated to remove the instantaneous frequency noise by monitoring power spectral density (PSD) of the frequency error signals in the real-time basis. The achieved PSD of frequency noise of a sample LD stabilized by the present system was less than 1105 Hz2/Hz for the Fourier frequency < 10 MHz. The reduced linewidth was estimated to be narrower than 400 kHz. The achieved minimum square root of the Allan variance was 3.910-11 at τ = 0.1 msec.

A numerically efficient analysis method, combining closed-form Green's functions with the method of moments (MoM) of the mixed potential integral equation (MPIE) approach, is considered for the electromagnetic coupling problem through an aperture into a parallel plate waveguide (PPW), as a complementary problem to the microstrip patch structure problem, and then applied to the electromagnetic pulse (EMP) penetration problem. Some discussion on the advantages of the present method is also presented from the perspective of computational electromagnetics.

When a randomized algorithm elects a leader on anonymous networks, initial information (which is called in general initial condition in this paper) of some sort is always needed. In this paper, we study common properties of initial conditions that enable a randomized algorithm to elect a leader. In the previous papers, the author introduced the notion of transformation between initial conditions using distributed algorithms. By using this notion of transformation, we investigate the property of initial conditions for the leader election. We define that an initial condition C is p(N)-complete if there exists some randomized algorithm that elects a leader with probability p(N) on any size N network satisfying C. We show that we can divide p(N)-completeness into four types as follows. 1. p(N)=1: For any 1-complete initial conditions, there exists a deterministic distributed algorithm that can compute the size of the network for any initial information satisfying the initial condition. 2. inf p(N) >0: For any p(N)-complete initial conditions with inf p(N) >0, there exists a deterministic distributed algorithm that can compute an upper-bound for the size of the network for any initial information satisfying the initial condition. 3. inf p(N) converges to 0: The set of p(N)-complete initial conditions varies depending on the decrease rate of p(N). 4. p(N) decreases exponentially: Any initial condition is regarded as p(N)-complete.

This study attempts to demonstrate that activated leukocytes are involved in vascular shut down effect (VSD) in photodynamic therapy (PDT). Hydrogen peroxide (H2O2), a reactive oxygen specie (ROS) that is found in monocytes, was visualized under a confocal laser scanning microscope, and ROS formation was quantified by fluorescence image analysis. The fluorescence intensity was expressed as a gray level graded from 0 to 255. Only the fluorescence derived from monocytes that had ZnCP-III incorporated and were irradiated with an HeNe laser caused increases in the fluorescence distribution over time, while no change of distribution was observed in three other conditions (only Zn CP-III added, only HeNe laser irradiation, or non-treated). The result indicates that the photochemical reaction induced by excitation of a photosensitizer, and ROS was derived from the reaction-stimulated monocytes. The activated monocytes generated ROS themselves and H2O2 was visualized by the DCFH fluorescence method. In conclusion, the result clearly shows that activated monocytes are involved in the VSD effect.

In this paper, a network dimensioning approach suitable to the Internet is discussed. Differently from the traditional telephone networks, it is difficult to guarantee QoS for end-users even in a statistically sense due to an essential nature of an end-to-end communication architecture in the Internet. We should therefore adopt another approach, based on the traffic measurement. In the approach, the traffic measurement is performed for monitoring the end-to-end QoS. Then, the network adaptively controls the link capacities to meet the user's QoS demands. For this purpose, the underlying network should support such a capability that the link capacities can be flexibly reused. With the WDM network as an underlying network, an example scenario for network provisioning is finally illustrated.

The concept of a "standardized brain" is familiar in modern functional neuro-imaging techniques including PET and fMRI, but it has never been adopted for optical imaging studies that deal with a regional cortical area rather than the whole brain. In this paper, we propose a "standardized barrel cortex" for rodents, and present a method for mapping optically detected neural activity onto the standard cortex. The standard cortex is defined as a set of simple cortical columns, which are modeled on the cytoarchitectonic patterns of cell aggregates in cortical layer IV of the barrel cortex. Referring to its underlying anatomical structure, the method warps the surface image of individual cortices to fit the standard cortex. The cortex is warped using a two-dimensional free-form deformation technique with direct manipulation. Since optical imaging provides a map of neural activity on the cortical surface, the warping consequently remaps it on the standard cortex. Data presented in this paper show that somatosensory evoked neural activity is successfully represented on the standardized cortex, suggesting that the combination of optical imaging with our method is a promising approach for investigating the functional architecture of the cortex.

For several years, more and more people are joining the Internet and various kind of packets (so called transaction-, block-, and stream-types) have been transmitted in the same network, so that poor network conditions cause loss of the stream-type data packets, such as voices, which request smaller transmission delay time than others. We consider a switching node (router) in a network as an N-series M/G/1-type queueing model and have mainly evaluated the fluctuation of packet delay time and end-to-end delay time, using the two moments matching method with initial value, then define the delay jitter D of a network which consists of jointed N switching nodes. It is clarified that this network is not suitable for voice packets transmission media without measures.

The backward direction Soft Output Viterbi Algorithm (a backward SOVA) is compared with the conventional SOVA (a forward SOVA) in turbo code decoding. We find noticeable performance improvement for the backward SOVA when it is not terminated, which turns out to be due to a smaller reliability value, indicating that the termination conditions of the turbo encoder strongly affect the performance of the backward SOVA decoder. We also propose a hardware efficient serially mixed SOVA decoder composed of a forward SOVA decoder and a backward SOVA decoder. Simulation results show that the proposed serially mixed SOVA decoder has a 0.2 dB coding gain at 2.0 dB Eb/No over the forward SOVA for a typical turbo code example.

Besides single byte errors which are caused by single chip failures, semiconductor memories used in some applications, such as satellite memory systems, are highly vulnerable to random double bit errors. It is therefore necessary to design Double bit Error Correcting--Single b-bit byte Error Correcting (DEC-SbEC) codes which correct both random double bit errors and single b-bit byte errors. This correspondence proposes a class of generic DEC-SbEC codes that are applicable to computer memory systems using recent high density DRAM chips with wide I/O data, such as, 8, 16 or 32 bits per chip. The proposed DEC-S8EC codes are suitable for memory systems using DRAM chips with 8-bit I/O data, and require 24 check bits for practical information lengths such as 64 and 128 bits.

In this paper, genetic algorithms is employed to determine the shape of a conducting cylinder buried in a half-space. Assume that a conducting cylinder of unknown shape is buried in one half-space and scatters the field incident from another half-space where the scattered filed is measured. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the imaging problem is reformulated into an optimization problem. The genetic algorithm is then employed to find out the nearly global extreme solution of the object function such that the shape of the conducting scatterer can be suitably reconstructed. In our study, even when the initial guess is far away from the exact one, the genetic algorithm can avoid the local extremes and converge to a reasonably good solution. In such cases, the gradient-based methods often get stuck in local extremes. Numerical results are presented and good reconstruction is obtained both with and without the additive Gaussian noise.

The paper proposes a vision-based system for adaptively inferring the interactional intention of a person coming close to a robot, which plays an important role in the succeeding stage of human/robot cooperative handling of works/tools in production lines. Here, interactional intention is ranged in the meaning of the intention to interact/operate with the robot, which is proposed to be estimated by the human head moving path during an incipient period of time. To implement this intention inference capability, first, human entrance is detected and is modeled by an ellipse to supply information about the head position. Second, B-spline technique is used to approximate the trajectory with reduced control points in order that the system acquires information about the human motion direction and the curvature of the motion trajectory. Finally, Hidden Markov Models (HMMs) are applied as the adaptive inference engines at the stage of inferring the human interactional intention. The HMM algorithm with a stochastic pattern matching capability is extended to supply whether or not a person has an intention toward the robot at the incipient time. The reestimation process here models the motion behavior of an human worker when he has or doesn't have the intention to operate the robot. Experimental results demonstrate the adaptability of the inference system using the extended HMM algorithm for filtering out motion deviation over the trajectory.

We propose an efficient, low cost, multicast ATM switch which is fair to all inputs. The switch consists of a novel copy network which creates unicast packets in a fair manner, followed by a network that routes packets to their correct Address Translation Tables (ATT's) and ultimately a unicast routing network which ensures sequencing. The copy and routing networks are based on deflection routing. We show that our switch requires O(log N) stages and can be designed for any arbitrarily low level of packet loss. The theoretical results are backed up by simulations. Switching elements in both the copying and routing networks have O(1) bit complexity, making the overall bit level hardware complexity of the network O(N log N). The latency of the switch is proportional to the number of stages O(log N). Unlike other existing copy networks, our copy network drops packets in a fair manner and hence can provide quality of service (QoS) support. The switch is output queued and allows the delivery of multiple packets to the same destination during a time slot.