The home network system (HNS, for short) enables the flexible integration of networked home appliances, which achieves value-added integrated services. Assuring safety within such integrated services is a crucial issue to guarantee a high quality of life in smart home. In this paper, we present a novel framework for the safety of the HNS integrated services. We first propose a way to define safety in the context of the integrated services, which is characterized by local safety, global safety, and environment safety. We then propose a method that can validate the above three kinds of safety for given HNS implementations. Exploiting the concept of Design by Contract (DbC, for short), the proposed method represents every safety property as a contract between a provider and a consumer of an HNS object. The contracts are embedded within the implementations, and then are validated through elaborate testing. We implement the method using Java Modeling Language (JML, for short) and JUnit with a test-case generation tool TOBIAS. Using the proposed framework, one can define and validate the safety of HNS integrated services, systematically and efficiently.
Maintaining replicated data between nodes can improve the dependability of data. We propose a probabilistic trapezoid protocol for replicated data that combines the trapezoid protocol with the concept of a probabilistic quorum system. We analyzed the read availability, the latest version's read availability and the average number of nodes accessed for the protocol. Our numerical evaluations demonstrated that it improves not only the read availability but also the latest version's read availability. Furthermore, when the number of nodes is greater than 100, it could effectively reduce the system's load. We designed and implemented a file transfer protocol to replicate data. Experimental results proved that the trapezoid protocol could achieve a better throughput than the voting system or the grid protocol. Despite node failure, the probabilistic trapezoid protocol also achieved a relatively better throughput.
The mobile Internet is characterized by “Easy-come and easy-go” characteristics, which causes challenges for many content providers. The 24-hour clickstream provides a rich opportunity to understand user's behaviors. It also raises the challenge of having to cope with a large amount of log data. The author proposes a stream-mining oriented algorithm for user regularity classification. In the case study section, the author shows the case studies in commercial mobile web sites and presents that the recall rate of the following month revisit prediction reaches 80-90%. The restriction of the stream mining gives a small gap to the recall rates in literature, but the proposed method has the advantage of small working memory to perform the given task of identifying the high revisit ratio users.
We have been developing a volumetric computing graphics cluster system in the form of a PC cluster with its rendering and calculation performance enhanced by graphics boards and dedicated devices. The goal of the system is to perform real-time simulation for a practical surgical simulator. A space-partition scheme for parallel processing inevitably requires data communications for both simulation and visualization. We studied the effects of both types of communications through experiments. On the basis of the results, we discuss a performance model and propose a performance metric for time-restricted processing. To provide an example, we evaluated our VGCluster system by using the proposed metric. The metric shows the effect of sustaining scalability by using a dedicated image-composition device.
Of all the major world languages, Japanese is lagging behind in terms of publicly accessible and searchable corpora. In this paper we describe the development of JpWaC (Japanese Web as Corpus), a large corpus of 400 million words of Japanese web text, and its encoding for the Sketch Engine. The Sketch Engine is a web-based corpus query tool that supports fast concordancing, grammatical processing, ‘word sketching’ (one-page summaries of a word's grammatical and collocational behaviour), a distributional thesaurus, and robot use. We describe the steps taken to gather and process the corpus and to establish its validity, in terms of the kinds of language it contains. We then describe the development of a shallow grammar for Japanese to enable word sketching. We believe that the Japanese web corpus as loaded into the Sketch Engine will be a useful resource for a wide number of Japanese researchers, learners, and NLP developers.
In this paper, we propose an abstraction for maintaining XML data partition, especially for holistic twig joins processing in a cluster system through a multidimensional data model. As XML documents, XML schemas and queries are numerous and intricacy in our system, we extract their metadata to define such a relationship among them in a multidimensional data model. For the partitioning purpose, we propose a series of multidimensional analysis operations outlined in three basic steps: document clustering, query clustering and partition refinement. Each step yields partitions with their associated costs computed by a cost model that takes a query processing cost as the basis. During simulated distribution of partitions to cluster computers, we refine some partitions residing in an overloaded cluster node and redistribute them in order to achieve considerably well balanced costs among all cluster nodes. Finally, we show the effectiveness of our proposed method indicated by achieving minimized cost variance in the cluster system and good performance of query execution.
This paper proposes a new musical feature to classify MPEG-4 TwinVQ compressed data into musical genre without decoding to audio signals. To extract the musical feature, we use the LSP (Line Spectrum Pair) parameters directly extracted from a bitstream without any computation, and the Discrete Wavelet Transform (DWT). We experimented on 2,196 compressed music data collected from 10 musical genres and evaluated the performance of the musical feature for musical genre classification. The maximum of average correct ratio for musical genre classification was 81.7%. Experiment showed that the musical feature had very good performance for musical genre classification in the compressed domain of MPEG-4 TwinVQ audio compression.
With the demand for bilingual dictionaries covering domain-specific terminology, research in the field of automatic dictionary extraction has become popular. However, the accuracy and coverage of dictionaries created based on bilingual text corpora are often not sufficient for domain-specific terms. Therefore, we present an approach for extracting bilingual dictionaries from the link structure of Wikipedia, a huge scale encyclopedia that contains a vast number of links between articles in different languages. Our methods analyze not only these interlanguage links but extract even more translations from redirect page and link text information. In an experiment which we have interpreted in detail, we proved that the combination of redirect page and link text information achieves much better results than the traditional approach of extracting bilingual terminology from parallel corpora.
In this paper, we propose a routing protocol for mobile ad hoc networks called Contact-based Hybrid Routing (CHR) protocol where each node maintains potential routes to the nodes which it encountered. Only one route request message is forwarded along the potential route maintained by the source to the destination. In forwarding the route request message, if an intermediate node finds that the potential route is broken, the node uses the potential route maintained by itself to the next node. Based on this idea, our goal is to reduce the number of route request messages by maintaining a small amount of information at the nodes. The experimental results in random way point mobility and disaster evacuation mobility have shown that CHR could reduce the number of messages while keeping reasonable accessibility to the destinations.
This paper addresses the problem of broadcasting (and multicasting) focusing on the two points of energy efficient networking and of time efficient computing, where all base stations are fixed and each base station operates as an omni-directional antenna. We developed one broadcasting algorithm based on the Stingy method and based on the above performances. We evaluate this and the other two algorithms based on the Greedy and Dijkstra methods.
To handle ubiquitous sensor data, we have been developing a geographical-location-based P2P network called “Mill”. In a ubiquitous sensing environment, data manipulation by users and sensing devices may have some characteristics. For example, sensor data are constantly generated and users keep getting these data in a particular region. When handling such an operation on existing overlay networks, relaying nodes have to process many queries issued by users. In this paper, we discuss an implementation methodology of “Mill” considering the characteristics of data manipulation. And we can also support event driven behaviors and consider the feasibility of the deployment through the implementation based on HTTP. The performance of the implementation shows that one Mill node can handle ten thousands users and sensing devices.
We introduce the concept of sensor-based applications for the daily business settings of organizations and their individual workers. Wearable sensor devices were developed and deployed in a real organization, a bank, for a month in order to study the effectiveness and potential of using sensors at the organizational level. It was found that patterns of physical interaction changed dynamically while e-mail is more stable from day to day. Different patterns of behavior between people in different rooms and teams (p < 0.01), as well as correlations between communication and a worker's subjective productivity, were also identified. By analyzing a fluctuation of network parameters, i.e., “betweenness centrality, ” it was also found that communication patterns of people are different: some people tend to communicate with the same people in regular frequency (which is hypothesized as a typical pattern of throughput-oriented jobs) while some others drastically changed their communication day by day (which is hypothesized as a pattern of creative jobs). Based on these hypotheses, a reorganization, such that people having similar characteristics work together, was proposed and implemented.
Recently, manufacturing companies have been moving into product-based service businesses in addition to providing the products themselves. However, it is not easy for engineers in manufacturing companies to create new service businesses because their skills, mental models, design processes, and organization are optimized for product design and not for service design. In order to design product-based services more effectively and efficiently, systematic design methodologies suitable for the service businesses are necessary. Based on the case analysis of more than 40 Japan-US product-based services, this paper introduces a product-based service design methodology called DFACE-SI. DFACE-SI consists of five steps from service concept generation to service business plan description. Characteristic features of DFACE-SI include visualization tools to facilitate stakeholders' recognition of new opportunities and difficulties of the target product-based service. Opportunities and difficulties are recognized using the customer contact expansion model and the failure mode checklist, respectively, which are extracted from the service case analysis. We apply DFACE-SI to a pilot project and illustrate its effectiveness.