A wireless sensor networks MAC protocol for real-time applications

Wireless sensor networks (WSN) are designed for data gathering and processing, with particular requirements: low hardware complexity, low energy consumption, special traffic pattern support, scalability, and in some cases, real-time operation. In this paper we present the virtual TDMA for sensors (VTS) MAC protocol, which intends to support the previous features, focusing particularly on real-time operation. VTS adaptively creates a TDMA arrangement with a number of timeslots equal to the actual number of nodes in range. Thus, VTS achieves an optimal throughput performance compared to TDMA protocols with fixed size of frame. The frame is set up and maintained by a distributed procedure, which allows sensors to asynchronously join and leave the frame. In addition, duty cycle is increased or decreased in order to keep latency constant below a given deadline. Therefore, a major advantage of VTS is that it guarantees a bounded latency, which allows soft real-time applications.

A proof of convergence for Ant algorithms

A proof of convergence for Ant algorithms is developed. Ant algorithms were modeled as branching random processes: the branching random walk and branching Wiener process to derive rates of birth and death of ant paths. Substitution is then carried out in birth–death processes which proves that a stable distribution is surely reached. This indicates that Ant algorithms converge with probability one. This analogy models Ant algorithms complexity parameters such as the number of cycles, the degrees of freedom of problem and the number of ants.     

A symbolic framework for multi-faceted security protocol analysis

Verification of software systems, and security protocol analysis as a particular case, requires frameworks that are expressive, so as to properly capture the relevant aspects of the system and its properties, formal, so as to be provably correct, and with a computational counterpart, so as to support the (semi-) automated certification of properties. Additionally, security protocols also present hidden assumptions about the context, specific subtleties due to the nature of the problem and sources of complexity that tend to make verification incomplete. We introduce a verification framework that is expressive enough to capture a few relevant aspects of the problem, like symmetric and asymmetric cryptography and multi-session analysis, and to make assumptions explicit, e.g., the hypotheses about the initial sharing of secret keys among honest (and malicious) participants. It features a clear separation between the modeling of the protocol functioning and the properties it is expected to enforce, the former in terms of a calculus, the latter in terms of a logic. This framework is grounded on a formal theory that allows us to prove the correctness of the verification carried out within the fully fledged model. It overcomes incompleteness by performing the analysis at a symbolic level of abstraction, which, moreover, transforms into executable verification tools.     

Focus points and convergent process operators: a proof strategy for protocol verification

We present a method for efficiently providing algebraic correctness proofs for communication systems. It is described in the setting of μCRL [J.F. Groote, A. Ponse, The syntax and semantics of μCRL, in: A. Ponse, C. Verhoef, S.F.M. van Vlijmen (Eds.), Algebra of Communicating Processes, Workshops in Computing, Springer, Berlin, 1994, pp. 26–62] which is, roughly, ACP [J.C.M. Baeten, W.P. Weijland, Process Algebra, Cambridge Tracts in Theoretical Computer Science, vol. 18, Cambridge University Press, Cambridge 1990, J.A. Bergstra, J.W. Klop, The algebra of recursively defined processes and the algebra of regular processes, in: Proceedings of the 11th ICALP, Antwerp, Lecture Notes in Computer Science, vol. 172, Springer, Berlin, 1984, pp. 82–95] extended with a formal treatment of the interaction between data and processes. The method incorporates assertional methods, such as invariants and simulations, in an algebraic framework, and centers around the idea that the state spaces of distributed systems are structured as a number of cones with focus points. As a result, it reduces a large part of algebraic protocol verification to the checking of a number of elementary facts concerning data parameters occurring in implementation and specification. The resulting method has been applied to various non-trivial case studies of which a number have been verified mechanically with the theorem checker PVS. In this paper the strategy is illustrated by several small examples and one larger example, the Concurrent Alternating Bit Protocol (CABP).     

A formal framework for real-time information flow analysis

We view Multi-Level Secure (MLS) real-time systems as systems in which MLS real-time tasks are scheduled and execute, according to a scheduling algorithm employed by the system. From this perspective, we develop a general trace-based framework that can carry out a covert-timing channel analysis of a real-time system. In addition, we propose a set of covert-timing channel free policies: If a system satisfies one of our proposed security policies, we demonstrated that the system can achieve a certain level of real-time information flow security. Finally, we compare the relative strength of the proposed covert-timing channel free security policies and analyze whether each security policy can be regarded as a property (a set of execution sequences).     

An efficient cluster and decomposition algorithm for mining association rules

Conventional algorithms for mining association rules operate in a combination of smaller large itemsets. This paper presents a new efficient which combines both the cluster concept and decomposition of larger candidate itemsets, while proceeds from mining the maximal large itemsets down to large 1-itemsets, named cluster-decomposition association rule (CDAR). First, the CDAR method creates some clusters by reading the database only once, and then clustering the transaction records to the kth cluster, where the length of a record is k. Then, the large k-itemsets are generated by contrasts with the kth cluster only, unlike the combination concept that contrasts with the entire database. Experiments with real-life databases show that CDAR outperforms Apriori, a well-known and widely used association rule.     

A simple population protocol for fast robust approximate majority

We describe and analyze a 3-state one-way population protocol to compute approximate majority in the model in which pairs of agents are drawn uniformly at random to interact. Given an initial configuration of x’s, y’s and blanks that contains at least one non-blank, the goal is for the agents to reach consensus on one of the values x or y. Additionally, the value chosen should be the majority non-blank initial value, provided it exceeds the minority by a sufficient margin. We prove that with high probability n agents reach consensus in O(n log n) interactions and the value chosen is the majority provided that its initial margin is at least . This protocol has the additional property of tolerating Byzantine behavior in of the agents, making it the first known population protocol that tolerates Byzantine agents.     

A real-time flood-routed voice protocol for fibre optic local area networks

A simple real-time flood routing voice (RTFRV) protocol which is suitable for point-to-point arbitrarily connected fibre optic local area networks is described. Simulation on a 3 Mbit/s nine-node mesh network which employs the protocol has shown that it is capable of supporting about 50 simultaneous two-way voice conversations (or 100 users) with packet delay of less than 10 ms and without any loss of information. The overall results suggest that voice transmission on such a network is feasible and that it performs better than voice transmission over Ethernet. Furthermore, the network is also very robust and allows easy network reconfiguration.     

Cones and foci: A mechanical framework for protocol verification

We define a cones and foci proof method, which rephrases the question whether two system specifications are branching bisimilar in terms of proof obligations on relations between data objects. Compared to the original cones and foci method from Groote and Springintveld, our method is more generally applicable, because it does not require a preprocessing step to eliminate τ-loops. We prove soundness of our approach and present a set of rules to prove the reachability of focus points. Our method has been formalized and proved correct using PVS. Thus we have established a framework for mechanical protocol verification. We apply this framework to the Concurrent Alternating Bit Protocol.

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A probabilistic framework for real-time performance assessment of inferential sensors

A definition for the reliability of inferential sensor predictions is provided. A data-driven Bayesian framework for real-time performance assessment of inferential sensors is proposed. The main focus is on characterizing the effect of operating space on the reliability of inferential sensor predictions. A holistic, quantitative measure of the reliability of the inferential sensor predictions is introduced. A methodology is provided to define objective prior probabilities over plausible classes of reliability based on the total misclassification cost. The real-time performance assessment of multi-model inferential sensors is also discussed. The application of the method does not depend on the identification techniques employed for model development. Furthermore, on-line implementation of the method is computationally efficient. The effectiveness of the method is demonstrated through simulation and industrial case studies.     

A context model for fuzzy concept analysis based upon modal logic

In this paper we present interesting relationships between the context model, modal logic and fuzzy concept analysis. It has been shown that the context model proposed by Gebhardt and Kruse [Int. J. Approx. Reason. 9 (1993) 283] can be semantically extended and considered as a data model for fuzzy concept analysis within the framework of the meta-theory developed by Resconi et al. in 1990s. Consequently, the context model provides a practical framework for constructing membership functions of fuzzy concepts and gives the basis for a theoretical justification of suitably use of well-known t-norm based connectives such as min–max and product–sum rules in applications. Furthermore, an interpretation of mass assignments of fuzzy concepts within the context model is also established.     

Statistical process monitoring with independent component analysis

In this paper we propose a new statistical method for process monitoring that uses independent component analysis (ICA). ICA is a recently developed method in which the goal is to decompose observed data into linear combinations of statistically independent components [1 and 2]. Such a representation has been shown to capture the essential structure of the data in many applications, including signal separation and feature extraction. The basic idea of our approach is to use ICA to extract the essential independent components that drive a process and to combine them with process monitoring techniques. I², I_e² and SPE charts are proposed as on-line monitoring charts and contribution plots of these statistical quantities are also considered for fault identification. The proposed monitoring method was applied to fault detection and identification in both a simple multivariate process and the simulation benchmark of the biological wastewater treatment process, which is characterized by a variety of fault sources with non-Gaussian characteristics. The simulation results clearly show the power and advantages of ICA monitoring in comparison to PCA monitoring.     

A framework for real-time semantic social media analysis

This paper presents a framework for collecting and analysing large volume social media content. The real-time analytics framework comprises semantic annotation, Linked Open Data, semantic search, and dynamic result aggregation components. In addition, exploratory search and sense-making are supported through information visualisation interfaces, such as co-occurrence matrices, term clouds, treemaps, and choropleths. There is also an interactive semantic search interface (Prospector), where users can save, refine, and analyse the results of semantic search queries over time. Practical use of the framework is exemplified through three case studies: a general scenario analysing tweets from UK politicians and the public’s response to them in the run up to the 2015 UK general election, an investigation of attitudes towards climate change expressed by these politicians and the public, via their engagement with environmental topics, and an analysis of public tweets leading up to the UK’s referendum on leaving the EU (Brexit) in 2016. The paper also presents a brief evaluation and discussion of some of the key text analysis components, which are specifically adapted to the domain and task, and demonstrate scalability and efficiency of our toolkit in the case studies.     

A simulation model for eliciting scheduling knowledge: an application to the precast manufacturing process

This paper discusses the process of eliciting scheduling knowledge from a simulation model and the development of a dynamic modelling approach to the scheduling process in the precast concrete industry. Due to the problems associated with eliciting scheduling knowledge from an ‘expert’ in the precast industry or perhaps in most of the manufacturing industries, simulation is used to complement human knowledge in this paper. Such knowledge will be used for online support to advise production schedulers and for further development of the simulation model by incorporating the knowledge in the model and making it more dynamic. The paper suggests that dynamic selection of scheduling rules during real-time operation has been recognised as a promising approach to the scheduling process in the precast industry. For this strategy to work effectively, sufficient knowledge is required to enable the model to predict the most effective scheduling rule to meet current factory status. The paper concludes that if the knowledge rules are used effectively, they could be a considerable managerial tool for exploring and improving managerial practices. Recommendations have been made regarding the development of a more realistic and practical scheduling system.     

Support system for finite element analysis

This paper describes work aimed at developing an intelligent support system for finite element modeling and a methodology for managing input data model. Analyzing various statement structures of input data, three structural interface models — the hierarchical browser, the spread sheet and the model generator — are proposed for advanced representation and editing. Two knowledge models composed of macro visual data representation (user oriented model) and micro regularized data representation (processor oriented model) are revealed in conformity with the approach of object-orientation. Moreover, an extended relational schema composed of a composite object (assembly of functional elements) and several abstracted scalar indexes has been implemented for case retrieval.     

An efficient response-time analysis for real-time transactions with fixed priority assignment

In the general context of tasks with offsets (general transactions), only exponential methods are known to calculate the exact worst-case response time (WCRT) of a task. The known pseudo-polynomial techniques give an upper bound of the WCRT. In this paper, we present a new worst-case response-time analysis technique (mixed method) for transactions scheduled by fixed priorities, and executing on a uniprocessor system. This new analysis technique gives a better (i.e. lower) pseudo-polynomial upper bound of the WCRT. The main idea is to combine the principle of exact calculation and the principle of approximation calculation, in order to decrease the pessimism of WCRT analysis, thus allowing improving the upper bound of the response time provided while preserving a pseudo-polynomial complexity. Then we define the Accumulative Monotonic property on which a necessary condition of feasibility is discussed. We also propose, to speed up the exact and mixed analysis, the dominated candidate task concept that allows reducing significantly the number of critical instants to study in an analysis.     

A new measure of consistency for positive reciprocal matrices

The analytic hierarchy process (AHP) provides a decision maker with a way of examining the consistency of entries in a pairwise comparison matrix and the hierarchy as a whole through the consistency ratio measure. It has always seemed to us that this commonly used measure could be improved upon. The purpose of this paper is to present an alternative consistency measure and demonstrate how it might be applied in different types of matrices.