751,936 research outputs found

    Integrating libpesto with subversion

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    Subversion, an open-source centralized version control system, developed by CoallabNet, is currently the second most popular version control system, after the ever popular CVS. Like CVS, Subversion uses a client-server architecture, but has a cleaner, modular architecture. One set of subversion modules, are the filesystem backends modules of subversion. Two ``official'' backends are currently supplied with subversion, a berkleyDB based backend(bdb), and a custom filebased filesystem implementation (fsfs). At least another un-official backend module using an SQL-database exists. Pesto is a secure, decentralized, distributed peer-to-peer storage system, implemented both as a NetBSD filesystem, and as middelware, a portable C-library (libpesto). Currently two applications using libpesto have been written, a C\#\/.Net windows client, and a highly scalable serverfarm for Pesto, written in Java. In this project we integrate subversion with pesto, by creating a new filesystem backend for subversion using libpesto. The result is a version-control system, that works like a centralized version-control system, but has decentralized storage. We show that this system can be used for backup, mirroring of repositories, and as a decentralized version-control system

    A Self-Tuning procedure for resource management in InterCloud Computing

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    Beijing Key Laboratory on Integration and Analysis of Large-scale Stream Data, College of Computer Science, North China University of Technology, Beijing, China The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.InterCloud Computing is a new cloud paradigm designed to guarantee service quality or performance and availability of on-demand resources. InterCloud enables cloud interoperability by promoting the interworking of cloud systems from different cloud providers using standard interfacing. Resource management in InterCloud, considered as an important functional requirement, has not attracted commensurate research attention. The focus of this paper is to propose a Software Cybernetic approach, in the form of an adaptive control framework, for efficient management of shared resources in peer-to-peer InterCloud computing. This research effort adopts cooperative game theory to model resource management in InterCloud. The space of cooperative arrangements (resource sharing) between the participant cloud systems is presented by using Integer Partitioning to characterise the worst case communication complexity in peer to peer InterCloud. Essentially, this paper presents an Integer partition based anytime algorithm as an optimal cost solution to the bi-objective optimisation problem in resource management, anchored principally on practical trade-off between the desired performance (quality of service) and communication complexity of collaborating resource clouds

    Robust H8 design for resonant control in a CVCF inverter application over load uncertainties

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    CVCF (constant voltage, constant frequency) inverters are electronic devices used to supply AC loads from DC storage elements such as batteries or photovoltaic cells. These devices are used to feed different kinds of loads; this uncertainty requires that the controller fulfills robust stability conditions while keeping required performance. To address this, a robust H8 design is proposed based on resonant control to track a pure sinusoidal voltage signal and to reject the most common harmonic signals in a wide range of loads. The design is based on the definition of performance bounds in error signal and weighting functions for covering most uncertainty ranges in loads. Experimentally, the H8 controller achieves high-quality output voltage signal with a total harmonic distortion less than 2%Peer ReviewedPostprint (published version

    A review of convex approaches for control, observation and safety of linear parameter varying and Takagi-Sugeno systems

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    This paper provides a review about the concept of convex systems based on Takagi-Sugeno, linear parameter varying (LPV) and quasi-LPV modeling. These paradigms are capable of hiding the nonlinearities by means of an equivalent description which uses a set of linear models interpolated by appropriately defined weighing functions. Convex systems have become very popular since they allow applying extended linear techniques based on linear matrix inequalities (LMIs) to complex nonlinear systems. This survey aims at providing the reader with a significant overview of the existing LMI-based techniques for convex systems in the fields of control, observation and safety. Firstly, a detailed review of stability, feedback, tracking and model predictive control (MPC) convex controllers is considered. Secondly, the problem of state estimation is addressed through the design of proportional, proportional-integral, unknown input and descriptor observers. Finally, safety of convex systems is discussed by describing popular techniques for fault diagnosis and fault tolerant control (FTC).Peer ReviewedPostprint (published version

    The role of effective communication and trustworthiness in determining guests’ loyalty

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.This study investigates the role of trustworthiness and effective communication in the development of guests’ loyalty within the hotel sector. We propose and test a conceptual model that differentiates between two types of loyalty: attitudinal and behavioral. As hotels can control and manage how they communicate their desired characteristics to guests, we posit effective communication and a hotel’s trustworthiness as the key concepts in building loyalty. This study reports on the findings of a study based on 322 hotel guests. Data were analyzed using structural equation modeling. The results reveal that implementing effective communication methods leads to a trustworthy image, which in turn has a positive impact on attitudinal and behavioral loyalty. This research provides hotel managers with strategic directions for cultivating guest loyalty

    A variable structure control approach to active queue management for TCP with ECN

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    Cataloged from PDF version of article.It has been shown that the transmission control protocol (TCP) connections through the congested routers can be modeled as a feedback dynamic system. In this paper, we design a variable structure (VS) based control scheme in active queue management (AQM) supporting explicit congestion notification (ECN). By analyzing the robustness and performance of the control scheme for the nonlinear TCP/AQM model, we show that the proposed design has good performance and robustness with respect to the uncertainties of the round-trip time (RTT) and the number of active TCP sessions, which are central to the notion of AQM. Implementation issues are discussed and ns simulations are provided to validate the design and compare its performance to other peer schemes’ in different scenarios. The results show that the proposed design significantly outperforms the peer AQM schemes in terms of packet loss ratio, throughput and buffer fluctuation

    Piezoelectric Phononic Plates: Retrieving the Frequency Band Structure via All-electric Experiments

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    We propose an experimental technique based on all-electric measurements to retrieve the frequency response of a one-dimensional piezoelectric phononic crystal plate, structured periodically with millimeter-scaled metallic strips on its two surfaces. The metallic electrodes, used for the excitation of Lamb-like guided modes in the plate, ensure at the same time control of their dispersion by means of externally loaded electric circuits that offer non-destructive tunability in the frequency response of these structures. Our results, in very good agreement with finite-element numerical predictions, reveal interesting symmetry aspects that are employed to analyze the frequency band structure of such crystals. More importantly, Lamb-like guided modes interact with electric-resonant bands induced by inductance loads on the plate, whose form and symmetry are discussed and analyzed in depth, showing unprecedented dispersion characteristics.Comment: This is the version of the article before peer review or editing, as submitted by an author to Smart Materials and Structures. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-665X/ab4aa

    The effect of strategic supplementation with trans-10,cis-12 conjugated linoleic acid on the milk production, estrous cycle characteristics, and reproductive performance of lactating dairy cattle

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    Peer-reviewedThis is the author’s version of a work that was accepted for publication in Journal of Dairy Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Dairy Science, Volume 95, Issue 5, May 2012, Pages 2442-2451: DOI 10.3168/jds.2011-4632The objective was to determine the effects of a protected (lipid-encapsulated) conjugated linoleic acid (LE-CLA) supplement on milk production, estrous cycle characteristics, and reproductive performance in lactating dairy cows on a pasture-based diet. Spring calving dairy cows (n = 409) on a single pasture-based commercial dairy farm were used in a completely randomized block design. Cows were assigned to 1 of 2 dietary supplements [LE-CLA (n = 203) or no supplement (control, n = 206)]. The LE-CLA cows received 51 g/d of a lipid supplement containing 5 g of both trans-10,cis-12 and cis-9,trans-11 CLA from 0 to 60 d in milk. Milk samples were collected 3 times weekly, and each sample was analyzed for progesterone to determine the interval to first ovulation and estrous cycle characteristics. Milk yield and concentrations of fat, protein, and lactose were measured every 2 wk. Cows were inseminated following visual observation of estrus. The breeding season commenced on April 8, 2009 and continued for 16 wk. Transrectal ultrasonography was carried out at 30 to 36 d and 60 to 66 d post-AI to diagnose pregnancy. The LE-CLA treatment resulted in a decrease in milk fat concentration (36.9 ± 0.06 g/kg vs. 30.7 ± 0.06 g/kg for control and LE-CLA, respectively) and yield (0.91 ± 0.02 kg/d vs. 0.84 ± 0.02 kg/d for control and LE-CLA, respectively); however, milk yield was increased by LE-CLA supplementation (24.7 ± 0.7 kg/d vs. 27.2 ± 0.7 kg/d for control and LE-CLA, respectively), resulting in no overall difference in milk energy output. No effect of LE-CLA was observed on any estrous cycle characteristics or measures of reproductive performance. These results support that in pasture-based systems of dairy production, where energy intake limits milk production, energy spared by CLA-induced milk fat depression is partitioned toward increasing milk yield rather than toward body reserves

    An Efficient Asynchronous Peer to Peer Auction using Yao Oblivious Transfer

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    Distributed electronic auctions are increasingly preferred over centralized electronic auctions today. The success of peer-to-peer file sharing networks has made distributed electronic auctions a possibility. Due to trust and conflict of interest issues with centralized auctioneer systems, multiple auctioneers in distributed roles are preferred. However, there is a possibility of auctioneer node collusion [16] and auctioneer-bidder collusion and auctioneer-seller collusion in such mechanisms. To overcome these problems, a new peer-to-peer auction protocol [17] with auctioneers forming auctioneer groups has been proposed. This protocol keeps the auctioneers honest by ensuring that no single auctioneer in the group has absolute control over the auction process. But, it leads to multiple bid comparisons and thus increases redundancy. It also fails to enforce a secure bid comparison method and hence fails to provide privacy of bids. This thesis presents a modified version of this protocol where the oblivious transfer method [14] is used to solve the Yao millionaires\u27 problem [22] that arises between two auctioneer groups when they have to compare bids. Additionally, a 2nd price mechanism in which only the second highest bid is known to all the auctioneer groups except for the auctioneer group which holds the highest bid, ensures that no unnecessary bid comparisons are made between auctioneer groups. Hence, the result is an efficient auction protocol which is iterative, asynchronous, 2nd price and based on a peer to peer mechanism
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