For detecting the anomalous behavior of a user effectively, most researches have concentrated on statistical techniques. However, since statistical techniques mainly analyze the average behavior of a user's activities, some anomalies can be detected inaccurately. In addition, it is difficult to model intermittent activities performed periodically. In order to model the normal behavior of a user closely, a set of various features can be employed. Given an activity of a user, the values of those features that are related to the activity represent the behavior of the activity. Furthermore, activities performed in a session of a user can be regarded as a semantically atomic transaction. Although it is possible to apply clustering technique to these values to extract the normal behavior of a user, most of conventional clustering algorithms do not consider any transactional boundary in a data set. In this paper, a transaction-based clustering algorithm for modeling the normal behavior of a user is proposed. Based on the activities of the past transactions, a set of clusters for each feature can be found to represent the normal behavior of a user as a concise profile. As a result, any anomalous behavior in an online transaction of the user can be effectively detected based on the profile of the user.

Call Admission Control (CAC) is a very important issue in CDMA systems to guarantee a required quality of service (QoS) and to increase system capacity. In this paper, we proposed and analyzed the CAC scheme using multiple criterions (MCAC), which can provide a quicker processing time and better performance. One is based on the number of active users with the minimum/maximum threshold by considering the spillover ratio, and the other is based on the signal to interference ratio (SIR). If active users are lower/higher than the minimum/maximum number of users threshold (N_min )/(N_max ), we accept/reject the new call without any other considerations based on the first criterion. And if the number of active users is between the N_min and N_max, we consider the current SIR to guarantee QoS based on the second criterion. Then the system accepts the new call when the SIR satisfies the system requirements, otherwise, the call is rejected. The multiple criterions scheme is investigated and its performance is compared with the number of user based CAC and power based CAC.

A new scheme for evaluation of shapes of pips and craters formed by arc discharges on electrical contact surfaces is proposed. Measuring a height of a pip or a depth of a crater as well as an average diameter thereof with a scanning laser microscope and then putting a plot having the measured values as its vertical and horizontal coordinates enable us to numerically and briefly evaluate shapes of those pips and craters on arc-damaged contact surfaces. Some exemplary results obtained by this evaluation scheme are presented here.

A principal attraction of ATM networks, in both wired and wireless realizations, is that the key quality of service (QoS) parameters of every call, including end-to-end delay, jitter, and loss are guaranteed by the network when appropriate cell-level traffic controls are imposed at the user network interface (UNI) on a per call basis, utilizing the peak cell rate (PCR) and the sustainable cell rate (SCR) values for the multimedia--voice, video, and data, traffic sources. There are three practical difficulties with these guarantees. First, while PCR and SCR values are, in general, difficult to obtain for traffic sources, the typical user-provided parameter is a combination of the PCR, SCR, and the maximum burstiness over the entire duration of the traffic. Second, the difficulty in accurately defining PCR arises from the requirement that the smallest time interval must be specified over which the PCR is computed which, in the limit, will approach zero or the network's resolution of time. Third, the literature does not contain any reference to a scientific principle underlying these guarantees. Under these circumstances, the issue of providing QoS guarantees in the real world, through traffic controls applied on a per call basis, is rendered uncertain. This paper adopts a radically different, high level approach to the issue of QoS guarantees. It aims at uncovering through systematic experimentation a relationship, if any exists, between the key high level user traffic characteristics and the resulting QoS measures in a realistic operational environment. It may be observed that while each user is solely interested in the QoS of his/her own traffic, the network provider cares for two factors: (1) Maximize the link utilization in the network since links constitute a significant investment, and (2) ensure the QoS guarantees for every user traffic, thereby maintaining customer satisfaction. Based on the observations, this paper proposes a two-phase strategy. Under the first phase, the average "link utilization" computed over all the links in a network is maintained within a range, specified by the underlying network provider, through high level call admission control, i.e. by limiting the volume of the incident traffic on the network, at any time. The second phase is based on the hypothesis that the number of traffic sources, their nature--audio, video, or data, and the bandwidth distribution of the source traffic, admitted subject to a specific chosen value of "link utilization" in the network, will exert a unique influence on the cumulative delay distribution at the buffers of the representative nodes and, hence, on the QoS guarantees of each call. The underlying thinking is as follows. The cumulative buffer delay distribution, at any given node and at any time instant, will clearly reflect the cumulative effect of the traffic distributions of the multiple connections that are currently active on the input links. Any bounds imposed on the cumulative buffer delay distribution at the nodes of the network will also dominate the QoS bounds of each of the constituent user traffic. Thus, for each individual traffic source, the buffer delay distributions at the nodes of the network, obtained for different traffic distributions, may serve as its QoS measure. If the hypothesis is proven true, in essence, the number of traffic sources and their bandwidth distribution will serve asa practically realizable high level traffic control in providing realistic QoS guarantees for every call. To verify the correctness of the hypothesis, an experiment is designed that consists of a representative ATM network, traffic sources that are characterized through representative and realistic user-provided parameters, and a given set of input traffic volumes appropriate for a network provider approved link utilization measure. The key source traffic parameters include the number of sources that are incident on the network and the constituent links at any given time, the bandwidth requirement of the sources, and their nature. For each call, the constituent cells are generated stochastically, utilizing the typical user-provided parameter as an estimate of the bandwidth requirement. Extensive simulations reveal that, for a given link utilization level held uniform throughout the network, while the QoS metrics--end-to-end cell delay, jitter, and loss, are superior in the presence of many calls each with low bandwidth requirement, they are significantly worse when the network carries fewer calls of very high bandwidths. The findings demonstrate the feasibility of guaranteeing QoS for each and every call through high level traffic controls. As for practicality, call durations are relatively long, ranging from ms to even minutes, thereby enabling network management to exercise realistic controls over them, even in a geographically widely dispersed ATM network. In contrast, current traffic controls that act on ATM cells at the UNI face formidable challenge from high bandwidth traffic where cell lifetimes may be extremely short, in the range of µs. The findings also underscore two additional important contributions of this paper. First, the network provider may collect data on the high level user traffic characteristics, compute the corresponding average link utilization in the network, and measure the cumulative buffer delay distributions at the nodes, in an operational network. The provider may then determine, based on all relevant criteria, a range of input and system parameters over which the network may be permitted to operate, the intersection of all of which may yield a realistic network operating point (NOP). During subsequent operation of the network, the network provider may guide and maintain the network at a desired NOP by exercising control over the input and system parameters including link utilization, call admittance based on the requested bandwidth, etc. Second, the finding constitutes a vulnerability of ATM networks which a perpetrator may exploit to launch a performance attack.

In this letter we suggest sets of features to classify genres of web documents. Web documents are different from textual documents in that they contain URL and HTML tags within the pages. We introduce the features specific to web documents, which are extracted from URL and HTML tags. Experimental results enable us to evaluate their characteristics and performances. On the basis of the experimental results, we implement a user interface of a web search engine that presents documents grouped by genres.

In the process of visual servoing, images are often blurred when the camera is moving. To solve this problem, a visual servoing system is proposed based on image moments of a planar target. According to image moment errors, the system can drive a camera to approach a static target with a 3D translational velocity. In this paper, it was proved that 0- and 1-order image moments are not only image's blur invariants, but also include the information of a target's position relative to the camera. Besides, the state equation of a moving image was deduced, based on which the control structure and an adaptive control strategy of our visual servoing system were designed. At last, some simulation results were presented to demonstrate the validity of the system.

Recently, broadband access is widely spreading, and many broadband network E-commerce services are planned and developed. This article proposes a broadband online shop where a videoconferencing system is used to enable direct, face-to-face communication. It is important for a broadband online shop to understand what preference their customers want in order to provide them with more appropriate information. By using customer preferences, a salesclerk can have a serviceable conversation with few questions to his online customers. So, we are developing a visual Customer Relationship Management system (v-CRM system) that offers customer preferences to broadband network service such as broadband online shop. In this paper, we classify customer preferences, and describe three visualization methods that enable customer preferences to be intuitively understood quickly. We outline the v-CRM evaluation system and describe an experiment where we evaluated how accurately customer preferences can be recognized using these methods. The results show that v-CRM system is effective for understanding customer preferences.

A very general form of the probability density distribution of the fading envelope has been presented by M.Nakagami, including the Nakagami-Rice and Nakagami-Hoyt distributions as special cases. This paper gives the series form expanded in positive terms of the m-distribution for it. Previously, the feasibility of such an expansion was predicted, but there has been no explicit description to date. The properties of the well-known m-distribution and the positive sign in each term of this series make it practical for numerical calculation, approximation and analysis.

In policy-based management, in addition to deliver and enforce policies in managed systems, it is inevitable to manage the policy life-cycle. We mean the policy life-cycle as cyclic iteration of processes involving monitoring to see if the enforced policies actually work at operators' will and their adaptation based on monitoring. Enabling such policy life-cycle management by the current centralized management paradigm such as SNMP may, however, result in poor scalability and reliability. This is typically due to much bandwidth consumption for monitoring and communication failure between a management system and a managed system. It may also impose a heavy burden on the operators in analyzing management information for the policy adaptation. For a solution to that, we propose a scalable and reliable policy-based management scheme enabling the policy life-cycle management based on distributed management paradigm. In the scheme, we provide a new management script describing policies and how their life-cycle should be managed, and execute the script on the managed system with enough computation resources. The scheme can make the current policy-based management more scalable by reducing management traffic, more reliable by distributing management tasks to the managed systems, and more promising by relieving of the operators' burden. We implement a prototype system based on the scheme taking Differentiated Services as a policy enforcement mechanism, and evaluate the scheme from the following viewpoints: 1) the reliability, 2) relievability, and 3) scalability. The first two will be shown with a policy adaptation scenario in an operational network. The last one will be investigated in terms of the management traffic reduction by a management script, the management traffic required for the management of a management script, and the load on a managed system to execute management scripts. As deployment consideration of the proposed scheme besides technical aspects, we also discuss how the prototype system could be integrated with managed systems compliant to the standards emerging in the marketplace.

The market for IP convergence services is expanding rapidly due to the rising number of Internet users. To respond to market trends, service systems must provide services quickly. This paper discusses that application server called the service agent which provides IP convergence services. The service agent meets the requirements for four application servers, centralized intelligence, supporting various interfaces: service creativity and scalability. The architecture is based on that of AIN systems, but whole system is written in Java especially to achieve service creativity and scalability. As a result of trial manufacture, feasibility of the service agent and scalability was achieved. Enough performance was also confirmed to obtain for commercial services.

We describe a next generation service creation environment (SCE), which is designed to support efficient service application development for IP networks. Considering the IP-network environment we extract the features required for the next generation SCE and propose an architecture for the next generation SCE based on design concepts to provide these features. In our approach, we do not create large components, such as service features, or construct chains of them. Instead, we define application-programming interface (API) control flows through which we utilize existing APIs, such as open APIs. Since service providers, such as ASPs and third parties, must have some knowledge of the APIs, this capability will enable the development of services that correspond to various service provisioning patterns as well as to differentiation of services from those offered by other providers, without the addition of service components. The feasibility and productivity of the next generation SCE are evaluated by developing sample services, including a general Voice over IP (VoIP) service using a Parlay API and a presence service using a presence and availability management (PAM) API. Evaluation shows that the environment not only assists in the development of service applications but also raises the productivity of the next generation SCE itself, thus confirming its effectiveness the rapid, economical development of high-quality IP network services.

A power and spreading gain allocation strategy is considered to effectively provide data services for mobile users with different levels of priorities in a DS-CDMA system. The priority level of a user is specified by a factor that is a weighting on the data throughput of the user. Our strategy implements a relative prioritization that affords a trade-off between spectral efficiency and strict prioritization.

Using ultrafast nonlinear-optical response of organic dye films, a train of picosecond optical pulses can be converted into a space pattern of a mm scale. As applications of this technique we demonstrate a single-shot multichannel optical switching for 1 Tbit/s pulse trains, and a timing jitter suppression of pulse trains using a control system with femtoseconds time resolution.

Differentiated Services architecture provides a framework that enables relative differentiation of Assured Forwarding (AF) service. The differentiation is quantified by QoS parameters in terms of loss probability and maximum delay. We develop herein an efficient model to compute resource allocation in terms of buffer and service rate that satisfies the QoS differentiation between classes of service. To evaluate the performance of the proposed model, we conducted extensive simulation on both single-node and multi-node cases. The simulation studies show that the model can provide an efficient method to allocate network resources for aggregated traffic.

Timing noise of 160 GHz optical pulses has been evaluated over nine decades of Fourier frequency using the optoelectronic harmonic mixing technique. For down-converting the 160 GHz pulse intensity into a low-frequency IF signal, the fourth order modulation sidebands produced by a Mach-Zehnder intensity modulator have been employed. Phase noise power spectral density and timing jitter for 155.552-GHz optical time-division multiplexed pulses and 160.640-GHz passively mode-locked pulses are measured using the time domain demodulation and time interval analysis techniques, respectively.

The oscillation characteristics of a 40 GHz, 1-3 ps regeneratively and harmonically mode-locked erbium-doped fiber laser have been investigated in detail with respect to stability, linewidth, and mode hopping. We show that because the Q value of the microwave filter in the feedback loop is limited to around 1000, which is almost the same as that in a 10 GHz laser, the cavity length should not be greatly increased as this would result in as much as a fourfold increase in the number of longitudinal beat signals. We undertook a detailed stability analysis by using three cavity lengths, 60, 80, and 230 m. The 80 m long cavity greatly improved the long-term stability of the laser because the supermode noise was suppressed and there were not too many longitudinal modes. We measured the linewidth of the longitudinal mode of the laser using a heterodyne method, and it was less than 1 kHz. We also point out that there is a longitudinal mode hopping effect with time that is induced by very small changes in temperature.

Integral equation method is used to compute three-dimension-structure capacitance in this paper. Since some multi-conductor structures present regular periodic property, the periodic cell is used to reduce the computational domain with adding appropriate magnetic and electric walls. The periodic Green's function in the integral equation method is represented in the form of infinite series with slow convergence. In this paper, Shanks transformation is used to accelerate the convergence. Numerical examples show that the proposed method is accurate with a much higher efficiency in capacitance extraction for 3-D periodic structures.

In this letter, we investigate the path length priority effect of existing just-enough-time (JET) scheme for optical burst switching (OBS) in the multiple hop network environments. And, we propose a novel hop-by-hop priority increasing (HPI) scheme using the input fiber delay lines (FDLs) at each node. Simulation results showed that the proposed FDL/delayed reservation (DR) with HPI scheme can avoid the path length priority effect and enhance the end-to-end throughput in multiple hop network environments.

In 1960, the famous computer pioneer J.C.R. Licklider described a vision for human-computer interaction that he called "man-computer symbiosis. " Licklider predicted the development of computer software that would allow people "to think in interaction with a computer in the same way that you think with a colleague whose competence supplements your own. " More than 40 years later, one rarely encounters any computer application that comes close to capturing Licklider's notion of human-like communication and collaboration. We echo Licklider by arguing that true symbiotic interaction requires at least the following three elements: a complementary and effective division of labor between human and machine; an explicit representation in the computer of the user's abilities, intentions, and beliefs; and the utilization of nonverbal communication modalities. We illustrate this argument with various research prototypes currently under development at Mitsubishi Electric Research Laboratories (USA).

This paper considers the problem of providing relative service differentiation in IEEE 802.11 Wireless LAN by using different Medium Access Control (MAC) parameters for different service classes. We present an analytical model which predicts the saturation throughput of IEEE 802.11 Distributed Coordination Function with multiple classes of service. This model allows us to show that relative service differentiation can be achieved by varying the initial contention window alone. In this case, the saturation throughput of a station can be shown to be approximately inversely proportional to the initial contention window size being used by that station. The simulation results validate our analytical model.