AFM/STM observations were performed on sub nm thick C-Au-S film by co-operation process of plasma CVD and sputtering with using CH4, SF6 and Ar mixture gas and Au plate discharge electrode. From the refractive index values, the conductive granular molecules with a size of 0.4-0.6 nm were expected to exist in the film. For the film at thickness similar to the molecular size, Ra (arithmetic mean departures of roughness profile from the mean line) values were measured to be 0.712/6.10 nm by AFM/STM measurement, respectively. The one order large STM Ra value compared to the AFM Ra value suggests that the film contains conductive granular molecules.

A novel multi-phase charge-sharing technique is proposed for the dot-inversion method to reduce AC power consumption of the TFT-LCD column driver without requiring any external capacitor for charge conservation. Simple and easy-to-control circuitry is applied in the proposed method, and the power saving efficiency depends on number of charge phases. Increasing the number of charge phases, the saving power efficiency is also raised. Excluding power dissipation of switches, the power saving efficiency is up to 75% theoretically with infinite phases. For previous work, the maximum power saving efficient is 50% without external capacitor. The HSPICE simulation results including power dissipation of all switches show that the proposed method with seven charge phases (eight-column lines as one group) decreases the power consumption of 23-68% and 10-18%, respectively, compared with original circuit (without any low-power scheme) and previous low-power charge-recycling works.

A cache replacement policy which takes the transcoding time into account in making replacement decisions, for the emerging transcoding proxy servers is proposed. Simulation results show the proposed policy outperforms the conventional LRU in both the cache hit rate and the average object transcoding time.

A mobile ad hoc network (MANET) is characterized by multi-hop wireless links in the absence of any cellular infrastructure as well as by frequent host mobility. This paper proposes a SMPQ: Spiral-Multi-Path QoS routing protocol in a MANET, while the MAC sub-layer adopts the CDMA-over-TDMA channel model. This work investigates the bandwidth reservation problem of on-demand QoS routing in a wireless mobile ad-hoc network. The proposed approach increases the ability of a route to identify a robust path, namely a spiral-multi-path, from source host to destination host, in a MANET to satisfy certain bandwidth requirements. Two important contributions of the proposed spiral-multi-path are: (1) the spiral-multi-path strengthens route-robustness and route-stability properties and (2) the spiral-multi-path increases the success rate of finding the QoS route. Performance analysis results demonstrate that our SMPQ protocol outperforms other protocols.

Synchronous Gaussian code-division multiple access (CDMA) systems employing group-orthogonal signature waveforms are proposed and analyzed. All users in the system are divided into groups of users. The signature waveforms are constructed such that all the signature waveforms in one group are orthogonal to all the signature waveforms used in all other groups. This construction of signature waveforms ensures that there is no inter-group interference (i.e., among users in different groups), but at the expense of having intra-group interference (i.e., among users in the same group). However, by choosing a small size for each group, the intra-group interference can be effectively handled by a low-complexity, optimal (or suboptimal) multiuser detector. It is shown that a significant improvement in the system capacity can be achieved by the proposed technique over the conventional one that uses signature waveforms constructed from Welch-bound-equality (WBE) sequences. In particular, it is demonstrated that, while the conventional system's error performance is very sensitive to even small amount of overload, the proposed system with an appropriate design of signature waveforms can achieve a much higher overload (up to 300% as shown in the paper) with an excellent error performance.

This paper discusses far-end crosstalk (FEXT) cancellation methods for multicarrier transmission system. A system arrangement and its tap update method are proposed when FEXT cancelers and a frequency-domain equalizer (FEQ) are jointly adapted to combat channel intersymbol interference, FEXT, and other additive noise. We present mathematical formulation of minimum mean-square error (MSE) and the optimum tap coefficients for the FEXT cancelers and the FEQ when FEXT cancellation techniques are introduced for multiuser discrete multitone (DMT) based very high-speed digital subscriber line (VDSL) transmission. It is shown that FEXT cancellation enhances the achievable bit rate in FEXT-limited systems. Computer simulation and analytical results show that the performance of jointly adapted FEXT cancelers and an FEQ is better than that of separately adapted FEXT cancelers and an FEQ.

We implement an efficient Secure Socket Layer (SSL) accelerator, which is embedded in the kernel level and utilizes kernel threads as the same number of CPUs. In comparison with the conventional Apache with/without our SSL accelerator, the SSL accelerator significantly improves the web-server performance by up to 200%.

This letter presents a simple A/D converter based on the circle map. The converter encodes a dc input into a binary output sequence and has the trapping window that extracts an available part of the output sequence. Using the available part, the decoder provides an estimation by a fraction with variable denominator: it can realize higher resolution. Theoretical evidences for the estimation characteristics are given.

This letter examines a very simple iterative chip-by-chip multiuser detection strategy for spread spectrum communication systems. An interleaving-based multiple-access transmission technique is employed to facilitate detection. The proposed scheme can achieve near single-user performance in situations with very large numbers of users while maintaining very low receiver complexity.

The aim of this paper is to raise utilization of resource and handover success rate at handover time. The proposed method takes advantage of the moving history of a mobile host at connection admission control time. We demonstrate the benefit of the proposed method over previously proposed reservation schemes by simulation.

Recently, wireless networks have become a major sector in the telecommunication industry. More and more applications seek to become wireless. However, a major obstacle in adapting wired applications to wireless is the quality of service problem. Although the wireless bandwidth is improving at a fast pace, it still is not enough for modern multimedia applications. Even if we solve the bandwidth problem, the mobility of users also poses challenges for QoS provision. If the user moves randomly, how and where can resources be reserved in advance for roaming users to move smoothly and seamlessly? In this paper, we propose a method for predictive resource reservation in wireless networks. Resources reserved but not used will seriously affect the system performance. Therefore, we also have mechanisms to release the reserved resources when it is not used within a time limit and allow resources to be used temporarily by another mobile user. We compare the performance of our method with those of fixed allocation scheme and shadow cluster scheme. The results indicate its effectiveness and feasibility.

Mining traversal patterns on the Internet is one of critical issues for exploring the user access behaviors. In this paper, we propose a new data mining scheme for mining frequent trip traversal patterns on the Internet. First, we define a trip traversal as a historical contiguous sequence of web sites or web pages, which were surfed or visited on an information-providing system by one user. Next, we derive all of the maximal trip traversals by analyzing and filtering these collected trip traversals. For mining the large trip traversals from the maximal trip traversals, we present a data mining scheme integrated with the schemes presented in. Here, the extracted large trip traversals can be thought of as the realistic frequent browsed behaviors for most of users either on a web site or on an information-providing system, such as a proxy server. Finally, we implement and design a data mining system to explore the large trip traversal patterns in order to capture user access patterns to some proxy server.

Among the many scheduling algorithms which can guarantee delay bounds of sessions, the EDF scheduler with regulators has received wide attention since it can admit a very high number of sessions. However, due to regulators, EDF with regulators has difficulty in scalable implementation. To implement a regulator, a buffer and a timer are needed to restrict the incoming traffics. Given N number of sessions, N regulators are required. Moreover, due to regulators, the entire scheduling algorithm is not work-conserving. To enforce work-conserveness, it is known in the literature that additional buffers and a complex mechanism are required to bypass regulators. Thus, scalable implementation becomes much more difficult in the case of the work-conserving EDF with regulators. In this paper, however, we show that the buffers and timers used to implement regulators are unnecessary to guarantee delay bounds of admitted sessions in fixed-sized packet networks. Then, we can remove those unnecessary buffers and timers. By the removal, the resulting scheduling algorithm can be implemented in a scalable way and becomes work-conserving for free.

Suppose that we need to design a controller for the system x(t) = A x(t) + B u, u = -K x(t), y(t) = C x(t), where matrices A, B and C are given and K is the matrix to to determine. It is required to determine K so that y(t) should not exceed prescribed value (i.e., the peak of output y(t) is limited). This kind of specification, in general, difficult to satisfy, since the peak ymax of y(t) (we define ymax to be max0 t |y(t)|) is a non-trivial function of design parameter K, which can not be expressed explicitly generally. Therefore, a controller design with such specifications often requires try and error process. In this paper, we approximate ymax in the form of formal power series and give an efficient algorithm to compute the series. We also give a design example of a control system as an application of the algorithm.

Recently routing protocols for QoS aware multicast are actively studied, but there are few studies focusing on the scalability of link state advertisement when the available bandwidth of a link is updated along with the QoS aware multicast tree construction. This paper proposes a new QoS aware multicast routing protocol that is scalable in terms of the link state advertisement exchange. Our protocol has the following features; (1) A multicast network is divided into domains, and the advertisement of information on links within a domain is limited within the domain. (2) Among the border multicast routers, only the link state information of inter-domain links is advertised. As a result, the number of link state advertisement messages will be drastically reduced. (3) When a multicast tree spreads over multiple domains, the tree construction needs to be performed without information on links in other domains, and it is possible that the construction may fail. In order to cope with this problem, the crank back mechanism of a tree construction is introduced. This paper describes the detailed procedures and the message formats of our protocol. It also describes the evaluation of the number of exchanged link state advertisement messages and shows that our protocol can reduce the number comparing with the conventional protocols.

The explosive growth of the Web contents has led to increasing attention on two major challenges: scalability and high availability of network file system. In this paper, based on our previous reports, we introduced the concept of intermediate file handle to cover the heterogeneity of file system and proposed a new data consistency scheme to reduce the overhead of write request in the reliable network file system. In addition, we also proposed a simple load-sharing mechanism for NFS client to switch to a lightly-load server in order to improve the response time of READ requests. With such an approach, NFS Clients are always active. They issued their requests and waited the corresponding replies. Finally, we analyzed the new data consistency scheme. It shows truly that the scheme is able to improve the performance of our network file system

In this paper, we study reliable decentralized supervisory control of discrete event systems with a control architecture where certain controllable events are controlled under the conjunctive fusion rule, and certain others are controlled under the disjunctive fusion rule. We first introduce a notion of reliable co-observability with respect to such a partition of the controllable event set. We then prove that reliable co-observability together with Lm(G)-closure and controllability is a necessary and sufficient condition for the existence of a reliable decentralized supervisor under a given partition. Moreover, we present necessary and sufficient conditions for the existence of a partition of the controllable event set under which a given specification language is reliably co-observable.

Constraints have been used extensively for the construction of graphical user interfaces. User interface constraints that are declarative are more favorable but require sophisticated constraint planning algorithms. Constraint planning algorithms proposed previously are getting more and more complicated as they were asked to handle more general requirements. We believe that the difficulty is mainly caused by the complicated data structure that is translated directly from the problem. By a transformation, we propose a simplified graph model for the problem and prove that the constraint planning problem can be reduced to finding feedback vertex sets on the simplified graph model. We also consider the general problem of handling non-uniform user interface constraints.

Various network resources, including wireless access services and multimedia appliances (device) are expected to be available in ubiquitous computing environments. Since resource availability can change when a user migrates from one place to another, functions to monitor the availability of resources in use and, if necessary, switch from obsolete resources to new ones are necessary for continuous service provision. This paper proposes adaptive terminal middleware called AMID that performs policy-based dynamic resource selection and host-based session management to ease network administrative tasks, and hide session failures and resource changes from applications and a user. AMID supports two kinds of mobility; session maintenance on vertical handoff and device handoff (service mobility). By AMID, a mobile host keeps entire handoff control and session state to eliminate the need for network-layer or intermediate-node mobility support, and mitigate responsibility of devices for session management. AMID realizes a Reliable Virtual Socket (RVS), on top of real sockets, which employs a seamless session handoff mechanism for resource changes, and a reliable session resume mechanism against unplanned disconnection of a wireless link. It achieves seamless session handoff through a proactive soft handoff method; to conceal setup and signaling latency, it initiates setup procedures with neighbor resources in advance of actual handoff and utilizes multiple wireless interfaces and devices redundantly. We implemented AMID and a follow-me audio application on top of it to evaluate the performance. Redirection of audio streams from built-in speakers to external ones, and handoff between 802.11b and Cellular are autonomously performed when a user migrates in the house. We confirmed that AMID achieved reliable session maintenance against wireless link failure, concealed latency of handoff management, and prevented packet loss during handoff.

Hash-based IP traceback is a technique to generate audit trails for traffic within a network. Using the audit trails, it reconstructs not only the true attack paths of a Distributed Denial of Service attack (DDoS attack), but also the true path of a single packet attack. However, hash-based IP traceback cannot identify attacker nodes themselves because it has no audit trail on the subnet's layer-2 network under the detected leaf router, which is the nearest node to an attacker node on a layer-3 network. We propose a layer-2 extension to hash-based IP traceback, which stores two identifiers with packets' audit trails while reducing the memory requirement for storing identifiers. One of these identifiers shows the leaf router's interface through which an attacking packet came, and the other represents the ingress port on a layer-2 switch through which the attacking packet came. We implement a prototype on FreeBSD and evaluate it in a preliminary experiment.