509 research outputs found
Distributed state estimation for uncertain Markov-type sensor networks with mode-dependent distributed delays
This the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 John Wiley & Sons, Ltd.In this paper, the distributed state estimation problem is investigated for a class of sensor networks described by uncertain discrete-time dynamical systems with Markovian jumping parameters and distributed time-delays. The sensor network consists of sensor nodes characterized by a directed graph with a nonnegative adjacency matrix that specifies the interconnection topology (or the distribution in the space) of the network. Both the parameters of the target plant and the sensor measurements are subject to the switches from one mode to another at different times according to a Markov chain. The parameter uncertainties are norm-bounded that enter into both the plant system as well as the network outputs. Furthermore, the distributed time-delays are considered, which are also dependent on the Markovian jumping mode. Through the measurements from a small fraction of the sensors, this paper aims to design state estimators that allow the nodes of the sensor network to track the states of the plant in a distributed way. It is verified that such state estimators do exist if a set of matrix inequalities is solvable. A numerical example is provided to demonstrate the effectiveness of the designed distributed state estimators.This work was supported in part by the Royal Society of the U.K., the National Natural Science Foundation of China under Grants 60804028 and 61028008, the Specialized Research Fund for the Doctoral Program of Higher Education for New Teachers in China under Grant 200802861044, the Teaching and Research Fund for Excellent Young Teachers at Southeast University of China, the International Science and Technology Cooperation Project of China under Grant No. 2009DFA32050, and the Alexander von Humboldt Foundation of Germany
Model-Based Security Testing
Security testing aims at validating software system requirements related to
security properties like confidentiality, integrity, authentication,
authorization, availability, and non-repudiation. Although security testing
techniques are available for many years, there has been little approaches that
allow for specification of test cases at a higher level of abstraction, for
enabling guidance on test identification and specification as well as for
automated test generation.
Model-based security testing (MBST) is a relatively new field and especially
dedicated to the systematic and efficient specification and documentation of
security test objectives, security test cases and test suites, as well as to
their automated or semi-automated generation. In particular, the combination of
security modelling and test generation approaches is still a challenge in
research and of high interest for industrial applications. MBST includes e.g.
security functional testing, model-based fuzzing, risk- and threat-oriented
testing, and the usage of security test patterns. This paper provides a survey
on MBST techniques and the related models as well as samples of new methods and
tools that are under development in the European ITEA2-project DIAMONDS.Comment: In Proceedings MBT 2012, arXiv:1202.582
Properties of odd nuclei and the impact of time-odd mean fields: A systematic Skyrme-Hartree-Fock analysis
We present a systematic analysis of the description of odd nuclei by the
Skyrme-Hartree-Fock approach augmented with pairing in BCS approximation and
blocking of the odd nucleon. Current and spin densities in the Skyrme
functional produce time-odd mean fields (TOMF) for odd nuclei. Their effect on
basic properties (binding energies, odd-even staggering, separation energies
and spectra) is investigated for the three Skyrme parameterizations SkI3, SLy6,
and SV-bas. About 1300 spherical and axially-deformed odd nuclei with 16 < Z <
92 are considered. The calculations demonstrate that the TOMF effect is
generally small, although not fully negligible. The influence of the Skyrme
parameterization and the consistency of the calculations are much more
important. With a proper choice of the parameterization, a good description of
binding energies and their differences is obtained, comparable to that for even
nuclei. The description of low-energy excitation spectra of odd nuclei is of
varying quality depending on the nucleus
Finanzmärkte, Unternehmungen, Informationen: Ergebnisse des Projektes im Wintersemester 2015/2016
Der vorliegende Beitrag der Wirtschaftswissenschaftlichen Schriften ist ein Sammelband, der die Beiträge der Studierenden des 2. Fachsemesters im Masterstudiengang General Management aus dem Wintersemester 2015/2016 umfasst. Die Einzelbeiträge wurden in einer zwei Monate dauernden Projektarbeit im Herbst 2015 erarbeitet und im Januar 2016 präsentiert. Der diesjährige Themenschwerpunkt lag auf dem Bereich "Banken", jedoch fanden auch andere Bereiche Eingang in das Spektrum der Arbeiten. Das Besondere dieser Ausarbeitungen liegt darin, dass sie in Form eines journalistischen Artikels aufgebaut sind und die Autoren die Aufgabe hatten, eine auch für Nichtfachleute geeignete Form der Darstellung zu finden. Besonderer Wert wurde auch auf einen gut lesbaren Schreibstil und die Vielfalt der Gestaltungsformen gelegt. Die Arbeiten liegen hier in der Originalversion vor und wurden nicht redigiert. Die Fakten wurden nach bestem Wissen ermittelt, jedoch besteht kein Anspruch auf Vollständigkeit
Performance Analysis and Optimization of IEEE 802.11 Protocol in Wireless Ad Hoc Networks
作为新一代无线通信网络的核心技术之一,无线自组织网络技术已成为当前信息技术领域的一大研究热点。作为无线自组织网络的关键技术,媒体接入控制(MediumAccessControl,MAC)协议决定着无线信道的使用方式,并负责为节点分配无线通信资源,其性能的优劣直接影响无线信道的利用率和网络的整体性能。其中,IEEE802.11的MAC协议是目前无线自组织网络的测试系统和实际应用中使用最多的MAC协议之一,也是许多无线自组织网络MAC协议的研究基础。因此,系统研究IEEE802.11的性能并加以针对性的改进,具有极为重要的理论意义和广泛的应用价值。 IEEE802.11MAC协议以分布式协调功能...As one of the essential technologies of next generation mobile communication system, wireless Ad Hoc network has become the focus in the field of current information technologies. As the key component of wireless Ad Hoc networks, Media Access Control (MAC) protocols determine the usage mode of wireless channels and allocate radio resource for nodes, which can directly influence the efficiency of w...学位:工学博士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007015387
Structural constraints of pyocin S2 import through the ferripyoverdine receptor FpvAI
TonB-dependent transporters (TBDTs) mediate energized transport of essential nutrients into gram-negative bacteria. TBDTs are increasingly being exploited for the delivery of antibiotics to drug-resistant bacteria. While much is known about ground state complexes of TBDTs, few details have emerged about the transport process itself. In this study, we exploit bacteriocin parasitization of a TBDT to probe the mechanics of transport. Previous work has shown that the N-terminal domain of Pseudomonas aeruginosa–specific bacteriocin pyocin S2 (PyoS2NTD) is imported through the pyoverdine receptor FpvAI. PyoS2NTD transport follows the opening of a proton-motive force-dependent pore through FpvAI and the delivery of its own TonB box that engages TonB. We use molecular models and simulations to formulate a complete translocation pathway for PyoS2NTD that we validate using protein engineering and cytotoxicity measurements. We show that following partial removal of the FpvAI plug domain which occludes the channel, the pyocin's N-terminus enters the channel by electrostatic steering and ratchets to the periplasm. Application of force, mimicking that exerted by TonB, leads to unraveling of PyoS2NTD as it squeezes through the channel. Remarkably, while some parts of PyoS2NTD must unfold, complete unfolding is not required for transport, a result we confirmed by disulfide bond engineering. Moreover, the section of the FpvAI plug that remains embedded in the channel appears to serve as a buttress against which PyoS2NTD is pushed to destabilize the domain. Our study reveals the limits of structural deformation that accompanies import through a TBDT and the role the TBDT itself plays in accommodating transport
Biomechanical Testing of Spinal Segment Fixed by Arcofix System on the Swine Spine
Study DesignAn in vitro biomechanical study.PurposeTo evaluate the mechanical properties of the spinal segment in the intact, injured, and stabilized state after fixation by an Arcofix implant.Overview of LiteratureSeveral types of thoracolumbar spine injury necessitates anterior instrumentation. The Arcofix plate represents the latest generation of angular stablity systems. The biomechanical properties of these implants have not been sufficiently studied yet.MethodsA total of ten porcine specimens (levels Th12-L3) were prepared. The tests were performed for intact, injured, and implanted specimens. In each state, the specimen was subjected to a tension load of a prescribed force, and subsequently, twisted by a given angle. The force load was 200 N. The torsion load had a deformation character, i.e., the control variable was the twisting angle and the measured variable was the moment of a couple. The amplitude of the load alternating cycle was 3°. Another parameter that was evaluated was the area of the hysteresis loop. The area corresponds to the deformation energy which is dissipated during the cycle.ResultsA statistically significant difference was found between the intact and injured states as well as between the injured and implanted specimens. The statistical evaluation also showed a statistically different value of the hysteresis loop area. In the case of instability, the area decreased to 33% of the physiological value. For the implanted sample, the area increased to 170% of the physiological value.ConclusionsThe Arcofix implant with its parameters appears to be suitable and sufficiently stable for the treatment of the anterior column of the spine
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