Striping is a technique that distributes file content over multiple storage servers and thereby enables parallel access. In order to be able to provide a consistent view across file data and metadata operations, the file system has to track the layout of the file and know where the file ends and where it contains gaps. In this paper, we present a light-weight protocol for maintaining a consiste...

To perform dextrous manipulation e ciently, it is necessary to coordinate the interactions of many component processes. This paper investigates one approach to coordination: discrete-event systems. The applicability of discrete-event systems to the modeling of dextrous manipulation tasks is studied. Discrete-event control theory o ers formal methods for determining whether a coordinator of the ...

This paper deals with day-ahead static security assessment with respect to a postulated set of contingencies while taking into account uncertainties about the next day system conditions. We propose a heuristic approach to check whether, given some assumptions regarding these uncertainties, the worst case with respect to each contingency is still controllable by appropriate combinations of preve...

In this paper, we investigate the dual control problem*TCP #ow control at the TCP layer and ABR #ow control at the ATM layer. First, we observe that TCP #ow control and ABR #ow control cannot co-operate well. The worst case is that the slow start after packet loss causes high but unused ACR (Allowed Cell Rate) which raises the potential of cell loss and an under#owed switch queue which reduces ...

Calculating the WCET of mission-critical satellite applications is a challenging issue. The European Space Agency is currently undertaking the CryoSat mission, consisting of a radar altimetry satellite to be launched in 2005. This paper describes the challenges and the first experimental results of calculating the WCET of the Control and Data Management Unit (CDMU) subsystem of the satellite. T...

Mandatory access control (MAC) mechanisms control which users or processes have access to which resources in a system. MAC policies are increasingly specified to facilitate managing and maintaining access control. However, the correct specification of the policies is a very challenging problem. To formally and precisely capture the security properties that MAC should adhere to, MAC models are u...

This paper addresses point stabilization for the extended chained form (ECF), a control system that may be used to model a number of mechanical underactuated systems. A control law is proposed, based on well-known hybrid open-loop/feedback techniques, which exponentially stabilizes the origin of a dynamic extension of the ECF and ensures a degree of robustness to additive disturbance terms that...

Standard optimal control methods perform optimization in the time domain. However, many experimental settings demand the expression of the control signal as a superposition of given waveforms. Since this type of constraint is not time-local, Optimal Control Theory cannot be used without modifications. Simplex methods, used as a substitute in this case, tend to be less efficient and less reliabl...

Darcs is a distributed version control system based on a unique algebra of patches called Patch Theory. Patch Theory was originally described informally by David Roundy and the formalisation of Darcs basis continue to be an unresolved topic nowadays, which keeps open the question of Darcs reliability since it may fail in some corner cases. In this work, I follow a different approach, instead of...

This paper presents a new technique for generating linear fractional transformation based uncertainty models for use in the robustness analysis of flight control systems using the structured singular value . The proposed approach does not require closedform linear expressions for the aircraft dynamics – only a non-linear software model of the closed loop aircraft, which can be efficiently trimm...