On Secure Workflow Decentralisation on the Internet

Decentralised workflow management systems are a new research area, where most work to-date has focused on the system's overall architecture. As little attention has been given to the security aspects in such systems, we follow a security driven approach, and consider, from the perspective of available security building blocks, how security can be implemented and what new opportunities are presented when empowering the decentralised environment with modern distributed security protocols. Our research is motivated by a more general question of how to combine the positive enablers that email exchange enjoys, with the general benefits of workflow systems, and more specifically with the benefits that can be introduced in a decentralised environment. This aims to equip email users with a set of tools to manage the semantics of a message exchange, contents, participants and their roles in the exchange in an environment that provides inherent assurances of security and privacy. This work is based on a survey of contemporary distributed security protocols, and considers how these protocols could be used in implementing a distributed workflow management system with decentralised control . We review a set of these protocols, focusing on the required message sequences in reviewing the protocols, and discuss how these security protocols provide the foundations for implementing core control-flow, data, and resource patterns in a distributed workflow environment

Diborane as a reducing agent: Part VIII–Reduction of trifluoroacetylindoles to trifluoroethyl- and hydroxytrifluoroethylindoles and novel dimeric 2-trifluoro-l[1'-(3'-alkylindolino)]ethylboranes

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A Message-Optimal Distributed Graph Algorithm: Partial Precedence Constrained Scheduling

This paper presents a distributed algorithm for the partial precedence constrained scheduling problem. In the classical precedence constrained scheduling problem all the dependent tasks must be scheduled before the task itself can be scheduled. The partial precedence constrained scheduling problem is a generalized version of the original precedence constrained problem in the sense that the number of dependent tasks to be scheduled before the task itself can be scheduled is considered a variable. Using a directed graph to model the partial precedence constrained scheduling problem in which n nodes represent the tasks and e edges represent the precedence constraints, it is shown that the distributed algorithm requires O(e) messages and O(n) units of time and is optimal in communication complexity to within a constant factor

A Message-optimal Distributed Graph Algorithm: Partial Precedence Constrained Scheduling 1

Abstract: This paper presents a distributed algorithm for the partial precedence constrained scheduling problem. In the classical precedence constrained scheduling problem all the dependent tasks must be scheduled before the task itself can be scheduled. The partial precedence constrained scheduling problem is a generalized version of the original precedence constrained problem in the sense that the number of dependent tasks to be scheduled before the task itself can be scheduled is considered a variable. Using a directed graph to model the partial precedence constrained scheduling problem in which n nodes represent the tasks and e edges represent the precedence constraints, it is shown that the distributed algorithm requires O(e) messages and O(n) units of time and is optimal in communication complexity to within a constant factor

An O(√n) Distributed Mutual Exclusion Algorithm Using Queue Migration

In this paper a distributed algorithm is proposed that realises mutual exclusion among n nodes in a computer network. There is no common or global memory shared by the nodes and there is no global controller. The nodes of the network communicate among themselves by exchanging messages only. The proposed algorithm is based on queue migration and achieves a message complexity of O(√n) per mutual exclusion invocation. Under heavy load, the number of required messages approaches 2 per mutual exclusion

Propagation of plane waves in a rotating magneto-thermoelastic fiber-reinforced medium under G-N theory

The article is concernedwith the possibility of plane wave propagation in a rotating elastic medium under the action of magnetic and thermal fields. The material is assumed to be fibre-reinforced with increased stiffness, strength and load bearing capacity. Green and Nagdhi’s concepts of generalized thermoelastic models II and III have been followed in the governing equations expressed in tensor notation. The effects of various parameters of the applied fields on the plane wave velocity have been shown graphically

AUDIO EVENT DETECTION FROM ACOUSTIC UNIT OCCURRENCE PATTERNS

In most real-world audio recordings, we encounter several types of audio events. In this paper, we develop a technique for detecting signature audio events, that is based on identifying patterns of occurrences of automatically learned atomic units of sound, which we call Acoustic Unit Descriptors or AUDs. Experiments show that the methodology works as well for detection of individual events and their boundaries in complex recordings