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[Keyword] fragment(13hit)

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  • Fragmentation-Minimized Periodic Network-Bandwidth Expansion Employing Aligned Channel Slot Allocation in Flexible Grid Optical Networks

    Hiroshi HASEGAWA  Takuma YASUDA  Yojiro MORI  Ken-ichi SATO  

     
    PAPER-Fiber-Optic Transmission for Communications

      Pubricized:
    2021/06/01
      Vol:
    E104-B No:12
      Page(s):
    1514-1523

    We propose an efficient network upgrade and expansion method that can make the most of the next generation channel resources to accommodate further increases in traffic. Semi-flexible grid configuration and two cost metrics are introduced to establish a regularity in frequency assignment and minimize disturbance in the upgrade process; both reduce the fragmentation in frequency assignment and the number of fibers necessary. Various investigations of different configurations elucidate that the number of fibers necessary is reduced about 10-15% for any combination of upgrade scenario, channel frequency bandwidth, and topology adopted.

  • Defragmentation with Reroutable Backup Paths in Toggled 1+1 Protection Elastic Optical Networks

    Takaaki SAWA  Fujun HE  Takehiro SATO  Bijoy Chand CHATTERJEE  Eiji OKI  

     
    PAPER-Network Management/Operation

      Pubricized:
    2019/09/03
      Vol:
    E103-B No:3
      Page(s):
    211-223

    This paper proposes a defragmentation scheme using reroutable backup paths in toggled-based quasi 1+1 path protected elastic optical networks (EONs) to improve the efficiency of defragmentation and suppress the fragmentation effect. The proposed scheme can reallocate spectrum slots of backup paths and reroute of backup paths. The path exchange function of the proposed scheme makes the primary paths become the backup state while the backup paths become the primary. This allows utilization of the advantages of defragmentation in both primary and backup paths. We formulate a static spectrum reallocation problem with rerouting (SSRR) in the toggled-based quasi 1+1 path protected EON as an integer linear programming (ILP) problem. The decision version of SSRR is proven to be an NP-complete problem. A heuristic algorithm is introduced to solve the problem for large networks networks where the ILP problem is not tractable. For a dynamic traffic scenario, an approach that suppresses the fragmentation considering rerouting and path exchanging operations is presented. We evaluate the performances of the proposed scheme by comparing it to the conventional scheme in terms of dependencies on node degree, processing time of network operations and interval time between scheduled defragmentations. The numerical results obtained from the performance evaluation indicate that the proposed scheme increases the traffic admissibility compared to the conventional scheme.

  • A Study of Online State-of-Health Estimation Method for In-Use Electric Vehicles Based on Charge Data

    Di ZHOU  Ping FU  Hongtao YIN  Wei XIE  Shou FENG  

     
    PAPER-Artificial Intelligence, Data Mining

      Pubricized:
    2019/03/29
      Vol:
    E102-D No:7
      Page(s):
    1302-1309

    The real-time state-of-health (SOH) estimation of lithium-ion batteries for electric vehicles (EV) is essential to EV maintenance. According to situations in practical applications such as long EV battery capacity test time, unavailability of regular daily tests, and availability of full-life-cycle charge data of EV recorded on the charging facility big data platform, this paper studies an online in-use EV state-of-health estimation method using iterated extended Gaussian process regression-Kalman filter (GPR-EKF) to incorporate lithium-ion battery data at the macro time scale and the micro time scale based on daily charge data of electric vehicles. This method proposes a kernel function GPR (Gaussian process regression) integrating neutral network with cycles to conduct fitting for data at the macro time scale to determine colored measurement noise; in addition, fragment charge data at the micro time scale is adjusted with real-time iteration to be used as the state equation, which effectively addresses issues of real-time SOC calibration and nonlinearization. The pertinence, effectiveness and real-time performance of the model algorithm in online battery state-of-health estimation is verified by actual data.

  • Pre-Adjustment Rerouting for Wavelength Defragmentation in Optical Transparent WDM Networks

    Akihiro KADOHATA  Atsushi WATANABE  Akira HIRANO  Hiroshi HASEGAWA  Ken-ichi SATO  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E98-B No:10
      Page(s):
    2014-2021

    We propose a new extension to reconfiguration algorithms used to address wavelength defragmentation to enhance the path accommodation efficiency in optical transparent wavelength division multiplexing networks. The proposed algorithm suppresses the number of fibers employed to search for a reconfigurable wavelength channel by combining routes between the target path and the existing path in a reconfigured wavelength channel. This paper targets three main phases in reconfiguration: i) the reconfiguration trigger; ii) redesign of the wavelength path; and iii) migrating the wavelength paths. The proposed and conventional algorithms are analyzed from the viewpoints of the number of fibers, accommodation rate and the number of migrating sequences. Numerical evaluations show that the number of fibers is suppressed by 9%, and that the accommodation efficiency is increased by approximately 5%-8% compared to when reconfiguration is not performed.

  • Plasma Polymerization for Protein Patterning: Reversible Formation with Fullerene Modification

    Hayato TAKAHASHI  Naoya MURATA  Hitoshi MUGURUMA  

     
    LETTER-Organic Molecular Electronics

      Vol:
    E93-C No:2
      Page(s):
    211-213

    Partial plasma polymerization for coexistence of hydrophobic/hydrophilic area in several ten micrometer size is the typical technique for protein patterning. A hydrophobic hexamethyldisiloxane plasma-polymerized film (HMDS PPF) was deposited on a glass substrate and this surface was partially modified by subsequent nitrogen plasma treatment (hydrophilic surface, HMDS-N PPF) with a patterned shadow mask. An antibody protein (F(ab')2 fragment of anti-human immunoglobulin G) was selectively adsorbed onto the HMDS-N area and was not adsorbed onto the HMDS area. Distinct 8080 µm2 square spots surrounded by a non-protein adsorbed 80 µm-wide grid were observed. Then, when the protein modified by fullerene was used, the reversible patterning was obtained. This indicated that the modification by fullerene changed the hydrophilic nature of F(ab')2 protein to hydrophobic one, as a result, the modified protein was selectively adsorbed onto hydrophobic area.

  • Selective Adsorption of an Antibody onto a Plasma-Polymerized Film for Protein Patterning

    Atsunori HIRATSUKA  Naoya MURATA  Hitoshi MUGURUMA  Kazunari MATSUMURA  

     
    LETTER-Organic Molecular Electronics

      Vol:
    E91-C No:6
      Page(s):
    978-980

    Techniques for patterned modification of substrate surfaces are important for forming microarrays on protein chips. A hexamethyldisiloxane plasma-polymerized film (HMDS PPF) was deposited on a glass substrate and the resulting surface was partially modified by subsequent nitrogen plasma treatment with a patterned shadow mask. When surface adsorption of an antibody protein (F(ab')2 fragment of anti-human immunoglobulin G) was visualized by fluorescence microscopy, distinct 8080 µm2 square spots were observed, surrounded by a non-fluorescent 80 µm-wide grid. This pattern could be attributed to proteins selectively adsorbed onto the nitrogen plasma-treated regions but not onto the surface of pristine HMDS PPF. This provided a simple fabrication method of protein patterning.

  • UDP Large-Payload Capability Detection for DNSSEC

    Kenji RIKITAKE  Koji NAKAO  Shinji SHIMOJO  Hiroki NOGAWA  

     
    PAPER-Network Security

      Vol:
    E91-D No:5
      Page(s):
    1261-1273

    Domain Name System (DNS) is a major target for the network security attacks due to the weak authentication. A security extension DNSSEC has been proposed to introduce the public-key authentication, but it is still on the deployment phase. DNSSEC assumes IP fragmentation allowance for exchange of its messages over UDP large payloads. IP fragments are often blocked on network packet filters for administrative reasons, and the blockage may prevent fast exchange of DNSSEC messages. In this paper, we propose a scheme to detect the UDP large-payload transfer capability between two DNSSEC hosts. The proposed detection scheme does not require new protocol elements of DNS and DNSSEC, so it is applicable by solely modifying the application software and configuration. The scheme allows faster capability detection to probe the end-to-end communication capability between two DNS hosts by transferring a large UDP DNS message. The DNS software can choose the maximum transmission unit (MTU) on the application level using the probed detection results. Implementation test results show that the proposed scheme shortens the detection and transition time on fragment-blocked transports.

  • Efficient Methods for Determining DNA Probe Orders

    Hiro ITO  Kazuo IWAMA  Takeyuki TAMURA  

     
    PAPER

      Vol:
    E89-A No:5
      Page(s):
    1292-1298

    In STS-based mapping, it is necessary to obtain the correct order of probes in a DNA sequence from a given set of fragments or an equivalently a hybridization matrix A. It is well-known that the problem is formulated as the combinatorial problem of obtaining a permutation of A's columns so that the resulting matrix has a consecutive-one property. If the data (the hybridization matrix) is error free and includes enough information, then the above column order uniquely determines the correct order of the probes. Unfortunately this does not hold if the data include errors, and this has been a popular research target in computational biology. Even if there is no error, ambiguities in the probe order may still remain. This in fact happens because of the lack of some information regarding the data, but almost no further investigation has previously been made. In this paper, we define a measure of such imperfectness of the data as the minimum amount of the additional fragments that are needed to uniquely fix the probe order. Polynomial-time algorithms to compute such additional fragments of the minimum cost are presented. A computer simulation using genes of human chromosome 20 is also noted.

  • Database Allocation Modeling for Optimal Design of Distributed Systems

    Jae-Woo LEE  Doo-Kwon BAIK  

     
    PAPER-Distributed, Grid and P2P Computing

      Vol:
    E87-D No:7
      Page(s):
    1795-1804

    By using distributed database systems, many advantages can be obtained such as database management cost, efficiency, and high integrity of systems through allocating fragments to many distributed sites with horizontal/vertical fragmentation of global database schema. To minimize costs, distributed algorithms must be applied so that database fragments are allocated to optimal sites. It is useful to replicate fragments, such as allocating many copies in many sites including load balancing. But there are too many possible combinations of each site and fragment, making it impossible to find a solution in real time, i.e., it is an NP-complete problem. This paper proposes near optimal heuristic algorithms for minimizing cost by defining a cost model based on read and update queries that are requested in many sites. Various factors are applied to the proposed algorithms for sizing efficient network resources that compute database transactions as remote query or update requests for consistency in replicated database systems. For network load balancing, incoming network traffic table is defined in each site. A request transaction from unallocated sites to allocated sites can be accessed properly at any other replicated sites by using the network traffic table. Finally, some experimental results verified the proposed algorithms by comparing actual cases of database allocation.

  • Throughput Enhancement for Mobile Ad Hoc Networks by Using Transfer Rate Adaptation, Back-to-Back Transmission, and Frame Fragmentation

    Chien-Yuan LIU  Chun-Hung LIN  

     
    PAPER-Ad-hoc Network

      Vol:
    E87-B No:5
      Page(s):
    1064-1074

    Multi-rate capabilities are supported by the physical layers of most 802.11 devices. To enhance the network throughput of MANETs, transfer rate adaptation schemes at MAC layer should employ the multi-rate capability at physical and the information of previous transmissions provided by MAC and physical layers. In this paper, we propose a transfer rate adaptation scheme plus back-to-back frame transmissions, and fragmentation at MAC layer, named TRAF. TRAF adopts a bi-direction-based approach with an extended option to select an appropriate rate for frame transmission under fast changing channel conditions. Consecutive back-to-back frame transmissions to fully utilize good channel quality during a coherent time interval and fragmentation algorithm to maintain high throughput under worse channel conditions are recommended in TRAF. Extensive simulation is experimented to evaluate the performance of TRAF. Regarding simulation results, frame delivery ratio, network throughput, and fairness of TRAF are significantly improved by comparing to that of fix rate, ARF, RBAR, OAR, and AAR protocols.

  • Mitigating Data Fragmentation for Small File Accesses

    Woo Hyun AHN  Daeyeon PARK  

     
    LETTER-Software Systems

      Vol:
    E86-D No:6
      Page(s):
    1126-1133

    In traditional file systems, data clustering and grouping have improved small file performance. These schemes make it possible for file systems to use large data transfers in accessing small files, reducing disk I/Os. However, as file systems age, disks become too fragmented to support the grouping and clustering. To offer a solution to this problem, we describe a De-Fragmented File System (DFFS), which gradually alleviates fragmentation of small files. By using data cached in memory, DFFS dynamically relocates blocks of small fragmented files, clustering them on the disks contiguously. In addition, DFFS relocates small related files in the same directory, grouping them at contiguous disk locations.

  • An Efficient Task Scheduling Scheme for Mesh Multicomputers

    Oh Han KANG  

     
    PAPER-Computer Systems

      Vol:
    E80-D No:6
      Page(s):
    646-652

    In this paper, we propose an efficient task scheduling scheme, called CTS (Class-based Task Scheduling), to obtain high performance in terms of high system utilization and low waiting times for tasks. While a better submesh allocation scheme can improve system performance, an allocation policy alone cannot improve performance significantly. This is due to the fact that the FCFS task scheduling policy leads to large external fragmentation. The CTS strategy maintains four separate queues, one for each incoming task class. This avoids the blacking property incurred in the FCFS scheduling. To reduce the external fragmentation, a job tends to wait for an occupied submesh of the same size instead of using a new submesh in the CTS strategy. Simulation results indicate that the proposed scheduling strategy improves the performance compared to the FCFS scheduling policy by reducing the average waiting delay significantly.

  • High-Performance, Fair Access Control Method for Wireless LANs

    Yoshihiro TAKIYASU  Eiichi AMADA  

     
    PAPER

      Vol:
    E77-B No:7
      Page(s):
    855-861

    This paper proposes a request-grant-type multiple access control called bandwidth-request labeled-slot multiple access (BLMA) for wireless LANs. BLMA employs slotted ALOHA in the request stage and has an algorithm to avoid unfair access due to the capture effect in this stage. In BLMA, terminals transmit data using fixed length slots called fragment slots in the transmission stage. The base station assigns the fragment slots one by one to terminals for peer-to-peer communication in which terminals communicate directly. It also controls the retransmission based on the stop and wait automatic repeat request scheme. The base station retransmits data for the source terminal as much as it can. BLMA provides simple and fair access control, efficient link utilization, and easy implementation. It also allows modes to be easily changed automatically from peer-to-peer communication to store-and-forward communication in which terminals communicate via the base station. Design concepts of a wireless MAC discussed and details of BLMA are described. The evaluation results of the BLMA are also shown.