Details of a Researcher - Nishi, Hiroaki

Papers - Nishi, Hiroaki

Division display 221 - 240 of about 314 ／ All the affair displays >>

An expression of system connection considering transmission delay

Kenji Natori, Hiroaki Nishi and Kouhei Ohnishi

Electrical Engineering in Japan (SCRIPTA TECHNICA-JOHN WILEY & SONS) 170 ( 1 ) 45 - 54 2010.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 0424-7760

This paper presents an expression of system connection considering transmission delay. In a research field of decentralized system or information system, the expression method of the system connection is a very important issue. Therefore, several expression methods of system connection have been proposed so far. However, those expressions are mainly based on binary operations without consideration for the transmission delays on connection paths although the concept of time is very important for expression of system connection. In this paper, expression methods of system connection considering transmission delays on the paths are proposed. Those expressions are based on exponential-type expression and can express both connections and transmission delays. Furthermore, the expression that can express connections, transmission delays, and past subsystems is also proposed. As one example of the application of proposed expressions, application for path selection of the design of network-based control system is described. © 2009 Wiley Periodicals.

Access to Document (DOI)

コールドブートアタックに対する防御手法の提案

池原幸司, 西宏章

電気学会情報通信部門誌 (The Institute of Electrical Engineers of Japan) 130 ( 8 ) (to be appeared) - 1356 2010

Research paper (scientific journal), Single Work, Accepted, ISSN 0385-4221

This paper proposes four different methods for preventing cold boot attacks. These attacks exploit DRAM remanence to acquire private information stored in a memory. DRAM modules can keep stored values for many seconds without a power supply, in particular at low temperature. To address cold boot attacks, circuit-shorting method, SRAM preservation method and cell selection method are proposed. The integrated method of these methods is also proposed because these methods are independent and can be achieved together. These proposed methods are evaluated by using actual testbeds. © 2010 The Institute of Electrical Engineers of Japan.

Access to Document (DOI)

Self-organized Link State Aware Routing for Multiple Mobile Agents in Wireless Network

Akihiro Oda, Hiroaki Nishi

IEICE TRANSACTIONS on Communications E93-B ( 8 ) 2012-2021 2010

Research paper (scientific journal), Single Work, Accepted

A regular expression processor embedded in service-friendly router for future Internet

Yasutsugu Nagatomi, Michihiro Koibuchi, Hideyuki Kawashima, Koichi Inoue, Hiroaki Nishi

Proceedings of the International Conference on Parallel Processing Workshops (IEEE Computer Society) 82 - 88 2010

Accepted, ISSN 1530-2016

For the future application-friendly Internet, we have presented a router architecture that enables to interact with a variety of rich services. The proposed router snoops a traffic data stream, inspects the packet payload as well as packet headers, and stores the designated data in the associated database. The service-friendly router uses the technology of DPI (Deep Packet Inspection) for enriching services. For this purpose, high-throughput regular expression processing becomes a crucial component embedded in the router in order to extract the required information from traffic streams. Moreover, target patterns of the regular expression processing can be dynamically and frequently updated according to the applications requests. In this paper, we mainly focus on the design and evaluation of the high-throughput regularexpression processor. It accelerates the processing performance of OR matching (pipe(\)-based matching) that is familiar in various emerging applications of future Internet. The proposed regular-expression processor achieves a low overhead processing under the condition that the updates of the regularexpression patterns are frequently issued. Evaluation results show that the proposed processor achieves 6.0-Gbps throughput of regular-expression matching when using 45nm standard cell library. © 2010 IEEE.

Access to Document (DOI)

Distributed Demand Side Management system for home Energy Management

Yukio Suhara, Tomohisa Nakabe, Gouki Mine, Hiroaki Nishi

IECON Proceedings (Industrial Electronics Conference) (IEEE) 2430 - 2435 2010

ISSN 1553-572X

Energy Management System, including Demand Side Management, are contributing to energy saving. However, power demand for home consumers, unlike large power consumers, is considered difficult to control each electric device because these power demands depend on consumer's behavior. Therefore, predicting power demand eagerly requested. KNIVES (Keio University Network oriented Intelligent and Versatile Energy saving System) is an ICT based demand side management system and controls electric power by using distributed and cooperative power control algorithm. We propose a management system for households with a smart circuit breaker box, which can measure power consumption of each outlet and enables integrated control by using KNIVES. In addition, I propose prediction method of demand power in a household by using proposed system. © 2010 IEEE.

Access to Document (DOI)

Construction of energy measuring system in a university for cluster Energy Management System

Yuto Kamiyoshi, Tomohisa Nakabe, Gouki Mine, Hiroaki Nishi

IECON Proceedings (Industrial Electronics Conference) (IEEE) 2423 - 2429 2010

ISSN 1553-572X

To deal with environmental problems such as global warming and depletion of energy resources, energy conservation measures in the civilian sector and the spread of renewable energy are required strongly. As a next-generation energy system to achieve them, Cluster Energy Management System (CEMS) is beginning to be studied in Japan. CEMS is the energy management system, which cooperates with various dispersed power sources and buildings using information technology. CEMS monitors and adjusts energy supply and demand in real-time to form the best combination of them, and achieves high efficiency energy usage. In this study, the electricity energy measurement system using KNIVES (Keio University Network oriented Intelligent and Versatile Energy saving System) was build in Keio University Shonan Fujisawa Campus (SFC). In addition, it is declared that this system can predict electric power demand based on the past data obtained from itself. © 2010 IEEE.

Access to Document (DOI)

Construction method of dynamic microgrid by using optimized grouping method

Gouki Mine, Robert Borer, Friederich Kupzog, Hiroaki Nishi

IEEE International Conference on Industrial Informatics (INDIN) 780 - 785 2010

ISSN 1935-4576

Dynamic microgrid was proposed in our laboratory in order to utilize distributed power sources effectively. It means that structure of microgrid is varying according to demand fluctuation. To realize the dynamic microgrid, it is indispensable to obtain both energy demand and supply and keeps balance them by using ICT based sensor network. KNIVES (Keio University Network oriented Intelligent and Versatile Energy saving System) is an ICT based supply and demand side management system that supports distributed and cooperative power control. In this study, KNIVES is introduced to actual consumers such as care facility, school and store as a platform of dynamic microgrid. Topology of the microgrid is changeable dynamically, and it is determined to conduct optimized calculation by referring energy consumption data and targeted value set measured from individual groups. This paper describes construction method of the dynamic microgrid and evaluation of feasibility and availability from a standpoint of calculation cost. © 2010 IEEE.

Access to Document (DOI)

Effective data sharing system for fault tolerant structural health monitoring system

Yoshinao Matsushiba, Hiroaki Nishi

International Workshop on Advanced Motion Control, AMC (IEEE) 76 - 81 2010

Structural Health Monitoring (SHM) system is a promising technology to determine the health condition of a structure and localize its damage. SHM system is widely used, especially in gigantic structures for its strong requirements of safety. Many researches about SHM system have been conducting. However, conventional SHM system did not take account of an accidental collapse caused by earthquake. As a result, there is a possibility that sensor nodes, network links, and a center server cause failures in processing or storing of data gathered in the building. These failures may lose important data that contains useful information for post-analyzing the collapse. The data includes when, where and why the structure is damaged and collapsed. Theses information have a great deal of potential for preventing similar damage or collapse and it will make great contribution to accelerate future structural researches. To solve the problem of data losses in a damage, data sharing system for SHM system is proposed. This system shares data within sensor nodes. The proposed system achieves the following three processes; node search, backup node selection and backup data transfer process. It is important to conduct these processes under the condition of limited resources due to small and not powerful sensor nodes. Backup node selection is an important process of this system. This paper mainly focused on this selection. Round-trip time, a size of free memory space of backup nodes and value of displacement caused by vibration are used for the selection. In this paper, the selection method based on displacement was checked. An experiment was conducted by using practical sensor nodes and acceleration data. From the result of this experiment, proposed system could share data by using selection method based on displacement. © 2010 IEEE.

Access to Document (DOI)

Multi-context-aware cache accelerating processing on network processors for future internet traffic

Airi Akimura, Hiroaki Nishi

International Conference on Advanced Communication Technology, ICACT (IEEE) 1 377 - 382 2010

Accepted, ISSN 1738-9445

The next-generation backbone routers need large-bandwidth communication capability because of increased future Voice over Internet Protocol (VoIP) services. Providing these or other future ubiquitous services will require new Network Processor (NP) designs, since these protocols or services are expected to require enormous increases in processing power in order to address their fine-grain communication pattern. These improvements of processing power will not be enough for future NP designs due to the requirements of cost reduction and lower power consumption. To meet these requirements, the cache mechanism has received increasing attention in NP design. Cache can reduce the load and time needed for table lookup by taking advantage of temporal localities in network traffic. For these reasons P-Gear, an advanced cache-based network processor, has been proposed by our laboratory. P-Gear, which provides a sophisticated cache architecture, can be used not only for table lookup but also for determining processing results, and achieves high-speed packet processing. In this paper, the cache architecture of P-Gear is shown and an extended cache mechanism called Multi-Context-Aware cache is proposed. Multi-Context-Aware cache can improve the speed of packet processing because it can control cache entry by analyzing the packet header and payload. To evaluate the validity of this proposed method, simulators of SIP (Session Initiation Protocol)-Aware cache, IKE (Internet Key Exchange)-Aware cache and FTP (File Transfer Protocol)-Aware cache were designed as subsets of Multi-Context-Aware cache. According to the simulation results, SIP-Aware, IKE-Aware and FTP-Aware cache can all make contributions to improving the cache hit rate by managing cache entry. In addition, they all can reduce processing unit requirements.

Link state aware routing for multiple mobile robots in wireless sensor network

Akihiro Oda, Hiroaki Nishi

Proceedings of the 9th IASTED International Conference on Parallel and Distributed Computing and Networks, PDCN 2010 143 - 149 2010

In recent years, instead of wired communication, wireless communication technology has been utilized in many applications. Particularly, wireless sensor networks can be utilized as a communication medium of multiple mobile robots for environmental monitoring, security service, space exploration etc. In this paper, to accomplish reliable packet routing in mobile ad-hoc network, a novel QoS sensitive routing algorithm is discussed. Wireless network topology could be changing dynamically by robot movement, radio disturbance or fading in continuously shifting situation. Therefore, a packet routing algorithm should guarantee QoS by using some quality indicators of a wireless network. In proposed routing algorithm, routing table is constructed by using Received Signal Strength Indicator(RSSI) and the table information is periodically flooded in the network. Novel hash based routing entry management by using extended-MAC address can eliminate the overhead of message flooding. An analysis of the collision of hash values contributes to determine the length of the hash values, which is minimum required. Simulations are conducted to evaluate the effectiveness of proposed algorithm and to validate the theory in general wireless network routing algorithm.

Access to Document (DOI)

Implementation of lossy haptic data compression using integer DCT to FPGA

Hiroyuki Tanaka, Kouhei Ohnishi, Hiroaki Nishi

IECON Proceedings (Industrial Electronics Conference) (IEEE) 1726 - 1731 2010

Accepted, ISSN 1553-572X

In this paper, lossy compression based on Integer DCT (Discrete Cosine Transform) for haptic data is presented and implemented to an FPGA (Field Programmable Gate Array). The lossy data compression accomplishes to reduce data size of the haptic data. In the lossy data compression, DCT-based techniques are often used. The Integer DCT (IntDCT) achieves the operation of the DCT with the format of integer. The compatibility of the IntDCT with the FPGA is therefore high. The lossy compression method is applied to a bilateral control system and the efficacy is confirmed by experiments. © 2010 IEEE.

Access to Document (DOI)

Failure prediction method for network management system by using Bayesian network and shared database

Erwin Harahap, Wataru Sakamoto, Hiroaki Nishi

8th Asia-Pacific Symposium on Information and Telecommunication Technologies, APSITT 2010 2010

Network Management System (NMS) is a service that employs a variety of tools, applications, and devices to assist network administrators on monitoring and maintaining network. Keeping the network in high quality of service is the main purpose of NMS. This paper proposed a method to solve the network problem by making a prediction of failure based on network-data behavior. The prediction represented by conditional probability generated by Bayesian network. Bayesian network is a probability graphical model for representing the probabilistic relationship among a large number of variables and doing probabilistic inference with those variables. In order to describe how the prediction works, we discuss the prediction result by simulation on network congestion.

Environmental-amenity aware controller for demand side management

Tomohisa Nakabe, Hiroaki Nishi

IEEE International Conference on Industrial Informatics (INDIN) 798 - 803 2010

ISSN 1935-4576

Deterioration of indoor condition is confirmed by decreasing efficiency of working in earlier study. Maintaining indoor condition is an important factor to control electric appliances in living space. This paper focuses on a trade-off relationship between power consumption and environmental amenity. In DSM (Demand Side Management) system, a control method for controlling electric appliances should aware environmental amenity. In addition, life styles of the system users differs request of demand control policy. In this policy, there are three elements of control, power consumption control, environment control, and user defined control. Proposed control method integrates these elements of the control policy. In addition, the proposed method enables to compare some operational methods. Simulation results suggest a possible beneficial effect of the proposed method in the environmental-amenity aware DSM. © 2010 IEEE.

Access to Document (DOI)

Character-string Processing Architecture for High-throughput Complex Regular-Expression Matching

NAGATOMI Yasutsugu, ISHIDA Shinichi, HARASHIMA Shingo, KOIBUCHI Michihiro, KAWASHIMA Hideyuki, NISHI Hiroaki

情報処理学会研究報告. 計算機アーキテクチャ研究会報告 (情報処理学会) 184 ( 21 ) U1 - U9 2009.08

ISSN 0919-6072

正規表現は，ネットワーク侵入検知システム（NIDS）などをはじめ様々なネットワークアプリケーションで広く使われている．しかしこれらの多くはソフトウェアベースのため処理速度が遅くネットワークのサービス品質に影響を及ぼしている．高速な処理を妨げる要因の一つは処理時間の大半を占めるパターンマッチングである．NIDS のパターンマッチングに用いられるパターン数は膨大であり，かつ複雑な正規表現も含まれている．このような膨大かつ複雑な正規表現を高速で処理できるエンジンのニーズは高い．本論文では膨大なパターン処理を可能とするパターン絞り込み機構を提案する．Regular-expression is widely used in various network applications, such as a network intrusion detection system (NIDS). However, high-throughput regular-expression execution couldn't achieve enough processing throughput because most of NIDSs have been implemented by software. Pattern matching function, which is a part of regular-expression processing， requires comparatively longer processing time. A huge amount of patterns are used for this pattern matching in NIDS. High-throughput processing engine are strongly required in order to execute a large number of complicated regular expression. In this paper, a pattern filtering architecture is discussed that enables to achieve a large number of patterns matching.

Implementation of Bilateral Control System Based on Acceleration Control Using FPGA for Multi-DOF Haptic Endoscopic Surgery Robot

Hiroyuki Tanaka, Kouhei Ohnishi, Hiroaki Nishi, Toshikazu Kawai, Yasuhide Morikawa, Soji Ozawa, Toshiharu Furukawa

IEEE Trans. on Industrial Electronics (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC) 56 ( 3 ) 618-627 - 627 2009.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 0278-0046

Bilateral control systems are strongly required to apply to endoscopic surgeries. It is necessary that the system has enough degrees of freedom for applying various operation procedures including endoscopic surgery. When the degrees of freedom of the system are increased, the amount of control calculation is also increased, and it is hard to keep sampling periods short. The bilateral control systems, however, require comparatively shorter sampling periods, particularly the control system based on an acceleration control system. Hence, it is a difficult issue to increase the degrees of freedom of the bilateral control system. In this paper, the sampling period is kept short in the multi-degree of freedom system by using field programmable gate arrays as processors. The bilateral control system based on the acceleration control system is implemented in a robot system, which has 12 DOF, and some experimental results are shown, and the errors between the response of the master and slave robots are discussed. © 2009 IEEE.

Access to Document (DOI)

Design of acceleration control system considering current dynamics

Hiroyuki Tanaka, Kouhei Ohnishi, Hiroaki Nishi

Proceedings of the IEEE International Conference on Industrial Technology (IEEE) 591 - 596 2009

Accepted

Sampling periods in digital control systems have been shortened thanks to the development of both hardware and software technologies. In recent years, FPGA (Field Programmable Gate Array) has been applied to robot systems to achieve hard real-time system with short sampling periods. Due to the short sampling periods, the effect of the time quantization has been reduced. Some other hardware restrictions, however, become critical issue. In this paper, current dynamics in motor driver is considered as the hardware restriction. The current response dynamics acts as a low-pass filter, and it can be the restrictions of performance improvement. In the proposed method, the dynamics is modeled as low-pass filter, and the modeled dynamics is compensated by a phase-lead compensator. The tracking performance in an acceleration control system is improved by the proposed method. The effectiveness of the proposed method is validated through simulations and experimental results.

Access to Document (DOI)

Evaluation of cooperative demand control system on micro grid

Gouki Mine, Toshihiko Handa, Tomokazu Tachikawa, Yuji Watanabe, Jun Ichi Ichimura, Hiroaki Nishi

IECON Proceedings (Industrial Electronics Conference) (IEEE) 3593 - 3598 2009

ISSN 1553-572X

KNIVES (Keio University Network oriented Intelligent and Versatile Energy saving System) is an IT based supply and demand side management system that supports distributed and cooperative power control. In this study, KNIVES is constructed on a real experimental facility of microgrid. The facility includes some distributed power generator and controllable/uncontrollable loads. It is also connected with general power grid. Therefore, it can introduce the electric power from the power grid when the power supply is insufficient. An experiment of demand control was achieved in this facility and the affectivity of KNIVES was confirmed. In this experiment, error ratio of demand balancing with distributed and cooperative demand controls were evaluated and compared with that without the demand control. ©2009 IEEE.

Access to Document (DOI)

Quality of Connectivity Guarantee of ZigBee based Wireless Mobile Sensor Network

Akihiro Oda, Tomohisa Nakabe, Hiroaki Nishi

2009 7TH IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS, VOLS 1 AND 2 (IEEE) 452 - 457 2009

Accepted, ISSN 1935-4576

In recent years, instead of wired communication, wireless communication technology has been utilized in many applications. Particularly, sensor networks are used in cases such as environmental monitoring, security service, space exploration etc. In this paper, motion planning and keeping connectivity of multiple robots distributed in a ZigBee based sensor networks are discussed in order to sense their unknown surroundings. The multiple robots distributed in a ZigBee based sensor network exchange information each other over the wireless sensor network and accomplish cooperative tasks in a closed area. In a rescue task, it changes dynamically according to the continuously shifting situation. In this case, the robots need to keep connectivity between other robots in order to accomplish the tasks in the real world. The proposed method enables mobile robot to be controlled under non-holonomic constraint and it is controlled based on the indicator of communication connectivity, which is related to the quality of communication as a real-time and real world application.

Access to Document (DOI)

Lightweight data duplication for fault tolerant Structural Health Monitoring System

Yoshinao Matsushiba, Hiroaki Nishi

IFAC Proceedings Volumes (IFAC-PapersOnline) 42 ( 3 ) 255 - 258 2009

ISSN 1474-6670

Structural Health Monitoring (SHM) is a key technology for determining the health condition of structures, such as buildings and bridges. SHM is widely used especially in gigantic structures due to the requirements of safety. However, conventional sensor network system for SHM did not take account of an accidental collapse. As a result, there is a possibility that a sensor network node, a network link, and also a center server cause failures in processing or storing of data gathered system. These failures may lose important data that contains useful information for a post-analyzing of the collapse. To solve this problem, a lightweight data duplication system for SHM that prevents the data failures or loss is proposed. Proposed system consists of three functions; node search, backup node selection and backup data transfer function. In backup node selection, round-trip delay and a size of free memory space of backup nodes are used.

Access to Document (DOI)

Haptic communication system using FPGA and real-time network framework

Hiroyuki Tanaka, Kouhei Ohnishi, Hiroaki Nishi

IECON Proceedings (Industrial Electronics Conference) (IEEE) 2931 - 2936 2009

Accepted, ISSN 1553-572X

In this paper, a scheme for a haptic communication system is proposed by using an FPGA (Field Programmable Gate Array) and real-time network framework, RTnet. In the haptic communication system, the FPGA is used as a motion control processor, and the Linux-based real-time network framework is applied to the communication line between a master and a slave robot. The FPGA can execute control calculations in a short interval. Sending a large number of packets in a short period is, however, not acceptable for the communication line. In the haptic communication system, the FPGA execute the control calculation in every 50 μs, and the packets are sent in every 1 ms to prevent network congestion. The degrees-of-freedom(DOF) of the haptic device can be increased without increasing the number of sending packets, since the data of the each DOF is packed into one packet in a Linux module. In this paper, a master-slave haptic communication system is developed. The master side consists of a haptic device, whereas the slave side consists of a virtual haptic device and a virtual environment. The validity of the haptic communication system is shown through an experiment. ©2009 IEEE.

Access to Document (DOI)

　 Previous page - Next page 　