Distributed Agent-Based Load Balancer for Cloud Computing

In this paper we present a concept of an agent-based strategy to allocate services on a Cloud system without overloading nodes and maintaining the system stability with minimum cost. To provide a base for our research we specify an abstract model of cloud resources utilization, including multiple types of resources as well as considerations for the service migration costs. We also present an early version of simulation environment and a prototype of agent-based load balancer implemented in functional language Scala and Akka framework

Sensor Intelligence for Tackling Energy-Drain Attacks on Wireless Sensor Networks

In this paper we propose a model for intelligent agents (sensors) on a Wireless Sensor Network to guard against energy-drain attacks in an energy-efficient and autonomous manner. This is intended to be achieved via an energy-harvested Wireless Sensor Network using a novel architecture to propagate knowledge to other sensors based on automated reasoning from an attacked sensor

Temporal specification and deductive verification of a distributed component model and its environment

In this paper we investigate the formalisation of distributed and long-running stateful systems using our normative temporal specification framework. We analyse aspects of a component-oriented Grid system, and the benefits of having a logic-based tool to perform automated and safe dynamic reconfiguration of its components. We describe which parts of this Grid system are involved in the reconfiguration process and detail the translation procedure into a state-based formal specification. Subsequently, we apply deductive verification to test whether dynamic reconfiguration can be performed. Finally, we analyse the procedure required to update our model for reconfiguration and justify the validity and the advantages of our methodology

Dynamic reconfiguration of GCM components

We detail in this report past research and current/future developments in formal specification of Grid component systems by temporal logic and consequent resolution technique, for an automated dynamic reconfiguration of components. It is analysed the specification procedure of GCM (Grid Component Model) components and infrastructure in respect to their state behaviour, and the verification process in a dynamic and reconfigurable distributed system. Furthermore it is demonstrated how an automata based method is used to achieve the specification, as well as how the enrichment of the temporal specification language of Computation Tree Logic CTL with the ability to capture norms, allows to formally define the concept of reconfiguration

Specification and verification of reconfiguration protocols in grid component systems

In this work we present an approach for the formal specification and verification of the reconfiguration protocols in Grid component systems. We consider Fractal, a modular and extensible component model. As a specification tool we invoke a specific temporal language, separated clausal normal form, which has been shown to be capable of expressing any ECTL+ expression thus, we are able to express the complex fairness properties of a component system. The structure of the normal enables us to directly apply the deductive verification technique, temporal resolution defined in the framework of branching-time temporal logic

Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the current-voltage characteristics of the discharge have been interpreted

Enhancement of CO2 uptake and selectivity in a metal-organic framework by incorporation of thiophene functionality

The complex [Zn2(tdc)2dabco] (H2tdc = thiophene-2,5-dicarboxylic acid; dabco = 1,4-diazabicyclooctane) shows a remarkable increase in CO2 uptake and CO2/N2 selectivity compared to the non-thiophene analogue [Zn2(bdc)2dabco] (H2bdc = benzene-1,4-dicarboxylic acid; terephthalic acid). CO2 adsorption at 1 bar for [Zn2(tdc)2dabco] is 67.4 cm3 x g–1 (13.2 wt.%) at 298 K and 153 cm3 x g–1 (30.0 wt.%) at 273 K. For [Zn2(bdc)2dabco] the equivalent values are 46 cm3 x g–1 (9.0 wt.%) and 122 cm3 x g–1 (23.9 wt.%), respectively. The isosteric heat of adsorption for CO2 in [Zn2(tdc)2dabco] at zero coverage is low (23.65 kJ x mol–1), ensuring facile regeneration of the porous material. The enhancement by the thiophene group on the separation of CO2/N2 gas mixtures has been confirmed by both ideal adsorbate solution theory (IAST) calculations and dynamic breakthrough experiments. The preferred binding sites of adsorbed CO2 in [Zn2(tdc)2dabco] have been unambiguously determined by in situ single crystal diffraction studies on CO2 loaded [Zn2(tdc)2dabco], coupled with quantum chemical calculations. These studies unveil the role of the thiophene moieties in the specific CO2 binding via an induced dipole interaction between the CO2 and the sulfur center, confirming that enhanced CO2 capacity in [Zn2(tdc)2dabco] is achieved without the presence of open metal sites. The experimental data and the theoretical insights suggest a viable strategy for improvement of adsorption properties of already known materials through incorporation of S-based heterocycles within their porous structures

Defect model for the mixed mobile ion effect

This paper presents a new defect model for the mixed mobile ion effect. The essential physical concept involved is that simultaneous migration of two unlike mobile ions in mixed ionic glass is accompanied by expansion or contraction of the guest-occupied sites with distortion of surrounding glass matrix; in many cases, an intensity of the local stresses in glass matrix surrounding ionic sites occupied by foreign ions is much greater than, or at least comparable to the glass network binding energy. Hence, when the stress exceeds the breaking threshold, relaxation occurs almost immediately via the rupture of the bonds in the nearest glass matrix with generation of pairs of intrinsic structural defects. The specificity of the mechanism of defect generation leads to the clustering of negatively charged defects, so that rearranged sites act as high energy anion traps in glass matrix. This results in the immobilization of almost all minority mobile species and part of majority mobile species, so mixed mobile ion glass behaves as single mobile ion glass of much lower concentration of charge carriers. Generation of defects leads also to the depolymerization of glass network, which in turn results in the reduction of the glass viscosity and Tg as well as in the compaction of glass structure (thermometer effect). The magnitude of the mixed mobile ion effect is defined by the size mismatch of unlike mobile ions, their total and relative concentrations, the binding energy of the glass-forming network, and temperature. Although the proposed model is based upon the exploration of alkali silicate glass-forming system, the approach developed here can be easily adopted to other mixed ionic systems such as crystalline and even liquid ionic conductors.Comment: 33 pages, 2 figure

Safety and liveness of component-oriented protocols: a feasibility study

Interaction in both agent-based and component-based architectures is facilitated by sharable, verified and unambiguous protocols with desirable properties. An interaction protocol may be expressed as a logical theory e.g. dynamic logic, joint intention theory or event calculus, thereby enabling the proof of its properties and its correctness. This paper focuses on new joint work in specifying and proving properties such as safety and liveness, of interaction protocols, in componentbased frameworks. A safe and sound interaction allows no unpredictable states and transitions, and states allowed for the behaviour are only those that are defined by the protocol. Other properties such as termination, soundness, completeness, stability and fairness can be specified and verified for such protocols