An approach is proposed for constructing a dependable server cluster composed only of server nodes with all nodes running the same algorithm. The cluster propagates an IP multicast address as the server address, and clients multicast requests to the cluster. A local proxy running on each client machine enables conventional client software designed for unicasting to communicate with the cluster without having to be modified. Evaluation of a prototype system providing domain name service showed that a cluster using this technique has high dependability with acceptable performance degradation.

At the initial stage of developing parallel machines, a software monitor, which manages communication between host computers, program loading and debugging, is necessary. However, it is often a cumbersome job to develop such a monitoring system especially when the target takes a parallel architecture. To solve this problem, we developed an integrated monitor system called "Pot". "Pot" consists of a system runs on the host computer and simple code on a target machine. In order to reduce the development costs, the program on a target machine is as simple as possible while "Pot" on the host computer itself provides various functions for system development.

Field Configurable Self-assembly is a novel programmable force field based heterogeneous integration technology. Herein, we demonstrate application of the method to rapid, parallel assembly of similar and dissimilar sub-200 µm GaAs-based light emitting diodes at silicon chip substrates. We also show that the method is compatible with post-process collective wiring techniques for fully planar hybrid integration of active devices.

Multipath is a big problem for TCP traffic in traffic engineering. To solve it, hash functions such as CRC-16 are usually applied over source and destination address segments in packet headers. Through simulations and performance comparison of several multipath algorithms, it is found out that high network utilization achieved by using hash functions is at the expense of low fairness among coexisting TCP flows. It is also illustrated that packet size has significant influence on performance.

The conventional clustering method has the unique potential to be the framework for power-conserving ad hoc networks. In this environment, studies on energy-efficient strategies such as sleeping mode and redirection have been reported, and recently some have even been adopted by some standards like Bluetooth and IEEE 802.11. However, consider wireless sensor networks. The devices employed are power-limited in nature, introducing the conventional clustering approach to the sensor networks provides a unique challenge due to the fact that cluster-heads, which are communication centers by default, tend to be heavily utilized and thus drained of their battery power rapidly. In this paper, we introduce a re-clustering strategy and a power-limit constraint for cluster-based wireless sensor networks in order to address the power-conserving issues in such networks, while maintaining the merits of a clustering approach. Based on a practical energy model, simulation results show that the improved clustering method can achieve a lifetime nearly 3 times that of a conventional one.

In this paper, a new method is proposed to construct a visual secret sharing scheme with a general access structure for plural secret images. Although the proposed scheme can be considered as an extension of Droste's method that can encode only black-white images, it can encode plural gray-scale and/or color secret images.

In an optical time domain reflectometer type strain measurement system, we theoretically derive the shape of the Brillouin gain spectrum produced in an optical fiber under a parabolic strain distribution which is formed in a uniformly loaded beam. Based on the derived result, we investigate the effects of the parabolic strain distribution parameters and the measurement conditions such as the launched pulse width and the measurement position on the beam on the deformation of the Brillouin backscattered-light power spectrum shape. In addition, we investigate the strain measurement error resulting from the deformation of the power spectrum shape by analyzing the peak-power frequency at which the power spectrum is maximized.

Automatic text summarization has the goal of reducing the size of a document while preserving its content. Generally, producing a summary as extracts is achieved by including only sentences which are the most topic-related. DOCUSUM is our summarization system based on a new topic keyword identification method. The process of DOCUSUM is as follows. First, DOCUSUM converts the content words of a document into elements of a context vector space. It then constructs lexical clusters from the context vector space and identifies core clusters. Next, it selects topic keywords from the core clusters. Finally, it generates a summary of the document using the topic keywords. In the experiments on various compression ratios (the compression of 30%, the compression of 10%, and the extraction of the fixed number of sentences: 4 or 8 sentences), DOCUSUM showed better performance than other methods.

In this paper, we propose a method to introduce an A* search control into sentential matching mechanism for question-answering systems, in order to reduce the response time while the accuracy of the answer is preserved. The question answering is a new technology to retrieve not relevant documents but the answer(s) directly by combining several methodology including IR and IE. One of the essential processes is the sentential matching between the user's query and each sentence in documents. In general, in order to obtain matching score precisely in higher resolution, we need some processes with higher computational costs. We therefore introduce an A* search in which both the processing cost and the resolution of matching score are took into account simultaneously. According to the experiments in NTCIR3 QAC1 Task1, the system with the controlled search is 3.4-8.5 times faster than the system with no control.

Due to the explosive growth of the network technologies, 3D models and animations have led to a great interest in various media. Especially 3D mesh models (3D meshes), which approximate surfaces by polygonal meshes are widely used to model 3D objects. In 1D and 2D signals such as speech, audio, images, video, etc., the signal values are located on "grids", for example the signals of images are defined on pixels. Thus, the errors of such signals can be explicitly defined by differences of the values on the "grids". However since in the 3D meshes, vertices are located on arbitrary positions in a 3D space and are triangulated in arbitrary ways, the grids cannot be defined. This makes it difficult to measure error on the 3D meshes. In this paper, we propose a new numerical method to measure the errors between two different 3D meshes.

MC-CDMA has attracted significant attention as a downlink communication method for fourth generation mobile communication systems. However, MC-CDMA has a peak power problem, similarly to other nonspread multicarrier systems. In this paper, we propose a novel peak power reduction technique for MC-CDMA using code selection at the transmitter. In the proposed system, the transmitter selects the code shift pattern from plural pre-assigned code shift patterns in each cluster to minimize the output peak power of downlink signals. The proposed technique can achieve the blind code detection of transmitting codes at the receiver. However, the detection performance degrades if the number of users is extremely large or extremely small. Therefore, in this paper, a code detection error recovery technique is also considered.

Many cooperated web cache systems and protocols have been proposed. These systems, however, require expensive resources, such as external bandwidth and CPU power or storage of a proxy, while inducing hefty administrative costs to achieve adequate client population growth. Moreover, a scalability problem in the cache server management still exists. This paper suggests peer-to-peer client-clustering. The client-cluster provides a proxy cache with backup storage which is comprised of the residual resources of the clients. We use DHT based peer-to-peer lookup protocol to manage the client-cluster. With the natural characteristics of this protocol, the client-cluster is self-organizing, fault-tolerant, well-balanced and scalable. Additionally, we propose the Backward ICP which is used to communicate between the proxy cache and the client-cluster, to reduce the overhead of the object replication and to use the resources more efficiently. We examine the performance of the client-cluster via a trace driven simulation and demonstrate effective enhancement of the proxy cache performance.

In a question-answering (QA) task, "real" information retrieval, rather than document retrieval is required. Effective QA thus involves complicated and time-consuming processing, such as natural language processing and named-entity processing. To reduce the amount of processing needed, the quantity of documents in a database can be narrowed down during an initial stage of the answering procedure. This paper proposes a new evaluation measurement and compares the retrieval accuracy of initial-stage searching that uses "overall" document retrieval and "partial" passage retrieval with the TREC QA data set. The initial search and final result accuracy for various cutoff points defined according to the number of documents or words that are output is evaluated. A variety of experiments demonstrate that middle-length passage-retrieval is effective for QA, and short-length passage-retrieval could improve the accuracy of the final result for a specific question type.

Association mining extracts common relationships among a finite number of categorical data objects in a set of transactions. However, if the data objects are not categorical and potentially unlimited, it is impossible to employ the association mining approach. On the other hand, clustering is suitable for modeling a large number of non-categorical data objects as long as there exists a distance measure among them. Although it has been used to classify data objects in a data set into groups of similar objects based on data similarity, it can be used to extract the properties of similar data objects commonly appearing in a set of transactions. In this paper, a new clustering method, CLOCK, is proposed to find common knowledge such as frequent ranges of similar objects in a set of transactions. The common knowledge of data objects in the transactions can be represented by the occurrence frequency of similar data objects in terms of a transaction as well as the common repetitive ratio of similar data objects in each transaction. Furthermore, the proposed method also addresses how to maintain identified common knowledge as a summarized profile. As a result, any data difference between a newly collected transaction and the common knowledge of past transactions can be easily identified.

This paper presents a Japanese Question Answering (QA) system based on a "Question Answering as Abduction" perspective. This perspective regards QA as the process of abductively explaining why a question is true based on logical contents of appropriately described textual information. This perspective is strongly inspired by Jerry Hobbs et al.'s "Interpretation as Abduction". It is also a simple conceptualization of Harabagiu et al.'s logic based QA system. We reify this concept in our QA system called SAIQA-Is. This system was designed to output only most likely answer candidates to a question. This system was participated in NTCIR QAC1. SAIQA-Is provided very good results in Task 2 and Task 3 of the QAC experiments. This results demonstrated strong feasibility and high potential of our Question Answering as Abduction approach.

In this paper, we propose an answer seeking algorithm for question answering that integrates structural matching and paraphrasing, and report the results of our empirical evaluation conducted with the aim of examining effects of incorporating those two components. According to the results, the contribution of structural matching and paraphrasing was not so large as expected. Based on error analysis, we conclude that structural matching-based approaches to answer seeking require technologies for (a) coreference resolution, (b) processing of parse forests instead of parse trees, and (c) large-scale acquisition of paraphrase patterns.

Let us introduce n ( 2) nonlinear mappings fi (i = 1,2,,n) defined on complete linear metric spaces (Xi-1,ρ) (i = 1,2,,n), respectively, and let fi: Xi-1 Xi be completely continuous on bounded convex closed subsets Xi-1,(i = 1,2,,n 0), such that fi() . Moreover, let us introduce n fuzzy-set-valued nonlinear mappings Fi: Xi-1 Xi {a family of all non-empty closed compact fuzzy subsets of Xi}. Here, we have a fixed point theorem on the recurrent system of β-level fuzzy-set-valued mapping equations: xi Fiβ(xi-1,fi(xi-1)), (i = 1,2,,n 0), where the fuzzy set Fi is characterized by a membership function µFi(xi): Xi [0,1], and the β-level set Fiβ of the fuzzy set Fi is defined as Fiβ {ξi Xi | µFi(ξi) β}, for any constant β (0,1]. This theorem can be applied immediately to discussion for characteristics of ring nonlinear network systems disturbed by undesirable uncertain fluctuations and to fine estimation of available behaviors of those disturbed systems. In this paper, its mathematical situation and proof are discussed, in detail.

This paper describes a practical Japanese natural language Question Answering system adopting effective selection of dynamic passages, Lexico-Semantic Patterns (LSP), and Predictive Answer Indexing. By analyzing the previous TREC QA data, we defined a dynamic passage unit and developed a passage selection method suitable for Question Answering. Using LSP, we identify the answer type of a question and detect answer candidates without any deep linguistic analyses of the texts. To guarantee a short response time, Predictive Answer Indexing is combined into our overall system architecture. As a result of the three engineering techniques, our system showed excellent performance when evaluated by mean reciprocal rank (MRR) in NTCIR-3 QAC-1.

A reactive sputtering method using an Electron-Cyclotron-Resonance (ECR) microwave plasma was used to deposit Ni-Zn ferrite thin-films for a soft magnetic backlayer of Co-containing spinel ferrite thin-film perpendicular magnetic recording (PMR) media. The Ni-Zn spinel ferrite thin-films with a preferential orientation of (100) and a relatively low coercivity of 15 Oe were obtained at a high deposition rate of 14 nm/min and at a temperature below 200 degrees C. Although post-annealing treatment in air at 200 degrees C was effective to decrease the coercivity of the Ni-Zn ferrite thin-films, the saturation magnetization and initial permeability decreased and the surface smoothness was deteriorated simultaneously. The Ni-Zn ferrite thin-films prepared by ECR sputtering are promising as the backlayer of the perpendicular magnetic recording medium, but further improvement is required in terms of the soft magnetic properties, the grain size and the surface roughness.

A new technique to reduce the isolation network's size in a Marchand balun needed for perfect all-port matching and isolation is proposed. The proposed isolation circuit is realized using a coupled-line phase-inverter in place of the bulky 180line section that has been previously proposed. Analysis of the proposed circuit yields the required relationship between coupling coefficient and electrical length of the coupler. Based on the design equations, the circuit is experimentally demonstrated at 1.8 GHz and has shown excellent results. The obtained output return loss and isolation loss are more than 18 dB and 40 dB, respectively. The proposed balun was then applied to the application of a doubled-balanced ring-diode mixer. The designed mixer achieves a low conversion loss of 6 dB at its operating frequency, which is 1.5 dB lower than for a doubled-balanced diode mixer using a conventional impedance-transforming Marchand balun. The RF-IF and LO-IF isolations are well below 25 dB and 18 dB across 1 GHz RF operating bandwidth, respectively.