DS-CDMA provides a flexible support for the low-to-high bit rate of multimedia services upon a specific user's request. A simple capacity expression is derived for a power-controlled reverse link of orthogonal multi-code DS-CDMA with multiple connections. It is found that an orthogonal multi-code user having multiple connections is equivalent to a single connection user, but with a spreading factor reduced by a factor of the total number of parallel codes and a required signal energy per symbol-to-interference plus noise power spectrum density ratio which is the average taken over multiple connections. Furthermore, the use of antenna diversity is found equivalent to the use of higher spreading factor increased by a factor of the number of antennas.

This paper presents a method of extracting car license plates captured from the arbitrary directions by using symmetry features. The generalized symmetry transform (GST) produces continuous features of symmetry between two points by combining locality constraint and reflectional symmetry, but its time complexity of GST is increased by the second power of the radius of a searching window. To achieve considerable reduction of this time complexity, we propose a scan line based GST (SLGST) which calculates the symmetry between a pair of edge pixels along the scan lines. Instead of calculating the global symmetry of a license plate, we assign the symmetry contribution acquired from SLGST to the corner point estimated from two edge points and their gradient orientations. The right angle tuned SLGST (RATSLGST) is newly proposed to detect the right angle corners more effectively. Image normalization by image warping is adopted to make such segmentation of license plate and later identification much easier. We also adopt the verifier that evaluates a candidate license plate to enhance extraction rate. Our experiments show that the proposed method for extracting perspectively distorted license plates is fairly reliable.

This paper discusses encoding of vehicular position information using predictive algorithms in inter-vehicle communications (IVC) from the viewpoints of source coding and noisy channels. Two vehicular driving models are assumed; one is the 15-mode as a suburban rapid transit driving pattern, the other is called calming mode as a street-driving pattern. Three types of schemes are compared; a pulse code modulation (PCM) scheme, a predictive coding (PC) scheme, and the variable interval prediction (VIP) scheme that is proposed here. This paper assumes that precise position information is got from a positioning system, and that all the transmitters and receivers have common predictors. Performance comparisons of the three types of schemes are carried out both of noiseless and noisy channels. Results show that the VIP scheme is superior to any other scheme.

Recently, information display equipment such as a navigation system has often come to be installed in a vehicle, and a variety of useful information has been offered to the driver by voice and images while driving. The necessity of improving safety when the driver receives such information has come to be stressed. As one of the means of solving this problem, we can develop a system that presents the driving and road conditions information such as a lane changing car to the driver by using a warning sound. The purpose of our study is to clarify the effectiveness of an auditory display that uses spatial sounds on such a system. An experiment for measuring the driver's reaction time and eye movements to LED lighting during actual driving has been carried out to investigate whether the spatial sound can quicken the driver's operation and decrease human error. We evaluated the effectiveness by two measures, average reaction time and the number of largely delayed reactions. We considered that the average reaction time corresponds to the quickness of the driver's operation, and the number of largely delayed reactions corresponds to the probability of human error. As a result of the experiment, the use of directional sound clearly showed better performance than the use of monaural sound and no sound in the number of largely delayed reactions. Moreover, we analyzed the factors involved in delay of the reaction by the results of eye movement measurements. Consequently, it has been found that directional sound can decrease the number of the largely delayed reactions, which lead to an accident during actual driving.

Among ITS applications, it is very important to acquire detailed statistics of traffic flows. For that purpose, vision sensors have an advantage because of their rich information compared to such spot sensors such as loop detectors or supersonic wave sensors. However, for many years, vehicle tracking in traffic images has suffered from the problems of occlusion effect and illumination effect. In order to resolve occlusion problems, we have been proposing the Spatio-Temporal Markov Random Field model(S-T MRF) for segmentation of Spatio-Temporal images. This S-T MRF model optimizes the segmentation boundaries of occluded vehicles and their motion vectors simultaneously by referring to textures and segment labeling correlations along the temporal axis as well as the spatial axis. Consequently, S-T MRF has been proven to be successful for vehicle tracking even against severe occlusions found in low-angle traffic images with complicated motions, such at highway junctions. In addition, in this paper, we define a method for obtaining illumination-invariant images by estimating MRF energy among neighbor pixel intensities. These illumination-invariant images are very stable even when sudden variations in illumination or shading effect are occurred in the original images. We then succeeded in seamlessly integrating the method for MRF energy images into our S-T MRF model. Thus, vehicle tracking was performed successfully by S-T MRF, even against sudden variations in illumination and against shading effects . Finally, in order to verify the effectiveness of our tracking algorithm based on the S-T MRF for practical uses, we developed an automated system for acquiring traffic statistics out of a flow of traffic images. This system has been operating continuously for ten months, and thus effectiveness of the tracking algorithm based on S-T MRF model was proven.

Various niching methods have been developed to maintain the population diversity. The feature of these methods is to prevent the proliferation of similar individuals in the niche (subpopulation) based on the similarity measure. This paper demonstrates that they are effective to avoid premature convergence in a case where only one global optimum in multimodal functions is searched. The performance of major niching methods in such a case is investigated and compared by experiments using seven benchmark functions. The niching methods tested in this paper are deterministic crowding, probabilistic crowding, restricted tournament selection, clearing procedure and diversity-control-oriented genetic algorithm (DCGA). According to the experiment, each method shows a fairly good global-optimum-searching capability. However, no method can completely avoid premature convergence in all functions. In addition, no method shows a better searching capability than the other methods in all functions.

Finding corresponding edges is considered being the most difficult part of edge-based stereo matching algorithms. Usually, correspondence for a feature point in the first image is obtained by searching in a predefined region of the second image, based on epipolar line and maximum disparity. Reduction of search region can increase performances of the matching process, in the context of execution time and accuracy. Traditionally, hierarchical multiresolution techniques, as the fastest methods are used to decrease the search space and therefore increase the processing speed. Considering maximum of directional derivative of disparity in real scenes, we formulated some relations between maximum search space in the second images with respect to relative displacement of connected edges (as the feature points), in successive scan lines of the first images. Then we proposed a new matching strategy to reduce the search space for edge-based stereo matching algorithms. Afterward, we developed some fast stereo matching algorithms based on the proposed matching strategy and the hierarchical multiresolution techniques. The proposed algorithms have two stages: feature extraction and feature matching. We applied these new algorithms on some stereo images and compared their results with those of some hierarchical multiresolution ones. The execution times of our proposed methods are decreased between 30% to 55%, in the feature matching stage. Moreover, the execution time of the overall algorithms (including the feature extraction and the feature matching) is decreased between 15% to 40% in real scenes. Meanwhile in some cases, the accuracy is increased too. Theoretical investigation and experimental results show that our algorithms have a very good performance with real complex scenes, therefore these new algorithms are very suitable for fast edge-based stereo applications in real scenes like robotic applications.

This paper presents an active vision system for on-line traffic sign recognition. The system is composed of two cameras, one is equipped with a wide-angle lens and the other with a telephoto lens, and a PC with an image processing board. The system first detects candidates for traffic signs in the wide-angle image using color, intensity, and shape information. For each candidate, the telephoto-camera is directed to its predicted position to capture the candidate in a larger size in the image. The recognition algorithm is designed by intensively using built-in functions of an off-the-shelf image processing board to realize both easy implementation and fast recognition. The results of on-road experiments show the feasibility of the system.

This paper presents a flexible learning algorithm for the binary neural network that can realize a desired Boolean function. The algorithm determines hidden layer parameters using a genetic algorithm. It can reduce the number of hidden neurons and can suppress parameters dispersion. These advantages are verified by basic numerical experiments.

A siphon-trap of a Petri net N is defined as a place set S with S = S, where S = { u| N has an edge from u to a vertex of S} and S = { v| N has an edge from a vertex of S to v}. A minimal siphon-trap is a siphon-trap such that any proper subset is not a siphon-trap. The following polynomial-time algorithms are proposed: (1) FDST for finding, if any, a minimal siphon-trap or even a maximal class of mutually disjoint minimal siphon-traps of a given Petri net; (2) FDSTi that repeats FDST i times in order to extract more minimal siphon-traps than FDST. (3) STFM_T (STFM_Ti, respectively) which is a combination of the Fourier-Motzkin method and FDST (FDSTi) and which has high possibility of finding, if any, at least one minimal-support nonnegative integer invariant.

This letter presents text-independent speaker identification results for telephone speech. A speaker identification system based on Karhunen-Loeve transform (KLT) derived from codebook design using genetic algorithm (GA) is proposed. We have combined genetic algorithm (GA) and the vector quantization (VQ) algorithm to avoid typical local minima for speaker data compression. Identification accuracies of 91% were achieved for 100 Mandarin speakers.

The reception quality of terrestrial digital broadcasting when the directional pattern of a mobile terminal is controlled has been experimentally evaluated using test signal. It was found that the reception probabilities with a controlled directional pattern were significantly improved over the case when an omni-directional antenna was used.

The locally optimum rank detector achieves a simpler detector structure when reference observations, in addition to regular observations, are available. Without reference observations, we have to use the sign statistics of regular observations, and using the sign statistics results in a complex detector structure. Instead, more computations are necessary to deal with additional reference observations.

In this paper, we propose a new job scheduling method for distributed parallel systems that can simultaneously achieve two main goals of the job scheduling in those systems: to minimize the execution time of a parallel job without disturbing the execution of the other jobs. We try to achieve those goals by introducing a new scheduler, called active scheduler, that dynamically controls the priority of parallel programs and balances the workload of host computers depending on the status of the underlying runtime environment. We implemented a prototype system of the scheduler to evaluate its effectiveness. The result of experiments implies that the overhead of introducing the active scheduler is at most 15% of the original execution time, and it is in fact effective to adjust the execution of parallel programs to an actual distributed environment in which many users execute their jobs simultaneously.

In this paper, three algorithms are proposed for rate maximization (RM) of transmitted data in multichannel (MC) communications, subject to joint constraints on available energy budget and tolerable degradation of service (DOS). Altogether referred to as the RM algorithms, they consist of the EADRM, the DADRM, and the fDADRM algorithms. Based on the rate-distortion optimization theory, closed-form expressions for optimally distributing the energy (for EADRM) or DOS (for DADRM and fDADRM ) among the subchannels (SC's) are derived, when the bit allocation is pre-specified. The specification of bit allocations is achieved by the use of the so-called eligible bit allocation matrix (EBAM), which is a function of the total data rate and the number of SC's. A greedy approach is adopted, where the total data rate is kept on raising until the relevant constraints can no longer be satisfied. While all three RM algorithms essentially generate identical maximum data rates, the fDADRM algorithm is much faster than the other two in computation. As compared to the result achievable by a single-channel communication scheme, the RM algorithms produce a much higher data rate for spectrally shaped channels.

The one-sample locally optimum rank detector test statistics for composite signals in multiplicative and signal-dependent noise are obtained. Since the one-sample locally optimum rank detector makes use of the sign statistics of observations as well as the rank statistics, both 'even' and 'odd' score functions have to be considered. Although the one-sample locally optimum rank detector requires two score functions while the two-sample detector requires only one score function, the one-sample detector requires fewer calculations since it has to rank fewer observations.

This paper proposes a new blind adaptive algorithm for computing the weight vector of an antenna array system. The new technique utilizes a Generalized On-Off algorithm to obtain the weight vector from the pilot channel of IS2000 1X system, of which the processing gain can be controlled arbitrarily. The proposed algorithm generates a suboptimal weight vector maximizing the SINR (signal to interference plus noise ratio) with a linear computational load. Based on the analysis obtained from various simulations, it is observed that the proposed algorithm is suitable for the practical IS2000 1X mobile communication environments.

Advances in broadcast digitization have been rapid in Japan since the broadcasting satellite (BS) digital broadcast services commenced in December 2000. It requires that the receiver, which may also be connected to appliances using a Home Network, has an inbuilt HDD for storing interesting programs. However, it is difficult to guarantee QoS level on a Home Network composed of heterogeneous sub-networks. Therefore, for the purpose of an efficient and appropriate transmission of a video stream, such as MPEG over the Home Network, a new scalable MPEG transmission method is required. For this we propose a Scalability method allowing for Impairments Propagation (SIP), which takes into account the impairments propagated to other frames due to the loss of a macroblock in a given frame. In this paper, we introduce the SIP technique, analyze it mathematically, and evaluate its performance.

A method to characterise the wall voltage distribution in a three-electrode AC PDP cell is discussed. The method makes use of a firing voltage loop in a two-dimensional voltage plane. From this "fingerprint," data on the relative wall voltages as well as on the non-uniformity of the wall voltages can be inferred. The properties of the loop are explained using a simple numerical model based on field line tracing. The fingerprint method is applied to analyse ramp waveforms on the scan and data electrode of a surface discharge PDP. Many features of the measurements can be understood in terms of uniform wall voltage distributions on the dielectrics covering the electrodes. A more detailed analysis, however, shows that considerable wall voltage non-uniformities can exist, which play an important role in the firing behaviour of the cell.

We have successfully produced laterally-grown grains on large (300 350 mm) glass substrates by means of a newly developed excimer laser crystallization system that features a high-precision mask stage and an auto-focusing system. The original grains were produced with a steep beam edge and their lateral growth was extended by repeated irradiation and translation. TFTs fabricated with these extended grains were found to have mobilities that remained almost constant at 270 cm2/Vs (n-ch. TFTs) and 230 cm2/Vs (p-ch. TFTs) over a wide range of laser fluence (400-600 mJ/cm2).