A temporal logic-based model of event-driven nets

Decision procedures are presented for checking a small but useful class of properties for any finite-state system consisting of real-time discrete-event processes. A timed transition model (TTM) is used for representing real-time discrete-event processes, and real-time temporal logic (RTTL) is the assertion language in which the property to be verified is stated. The relationship of TTMs to other formalisms is summarized along with a complete definition of TTMs and an overview of RTTL. The construction of reachability graphs is discussed, two different procedures are presented for constructing reachability graphs, and the corresponding decision procedures are given. >

Responsive communication protocols must incorporate both real-time and fault-tolerant properties. In this paper, we propose a new method for detecting design faults in specifications of responsive communication protocols based on real-time temporal logic. We also present a case study where a connection establishment protocol for a plant control system is dealt with.

In this paper, we introduce a real-time temporal knowledge logic, called RTKL, which is a combination of real-time temporal logic and knowledge logic. It is showed that temporal modalities such as “always in an interval”, “until in an interval”, and knowledge modalities such as “knowledge in an interval” and “common knowledge in an interval” can be expressed in such a logic. The model checking algorithm is given. Furthermore, we add cooperation modalities to RTKL and get a new logic RATKL, which can express not only real-time temporal and epistemic properties but also cooperation properties. The model checking algorithm for RATKL is also given.

A (possibly infinite-state) real-time discrete-event plant is modeled as a timed transition system. The free (uncontrolled) behavior of the plant is usually unsatisfactory in some important respect. A specification (written in real-time temporal logic) of required plant behavior is therefore to be imposed on the plant. The key result is a controller development procedure which shows how to systematically develop control strategies for a class of safety properties. The procedure isolates the unsafe part of the behavior, and gives a set of conditions under which the unsafe behavior can be made safe. If the conditions are satisfied, then the plant is guaranteed to satisfy the required specification. The states of the system are not explicitly represented in the design procedure; instead, predicates and predicate transformers, are used to overcome some of the problems of combinatorial explosion of states in large systems. >

A specification architecture for multimedia systems in Open Distributed Processing

The inference of performance models from low-level location tracking traces provides a means to gain high-level insight into customer and/or resource flow in complex systems. In this context our earlier work presented a methodology for automatically constructing Petri Net performance models from location tracking data. However, the capturing of synchronisation between service centres – the natural expression of which is one of the most fundamental advantages of Petri nets as a modelling formalism – was not explicitly supported. In this paper, we introduce mechanisms for automatically detecting and incorporating synchronisation into our existing methodology. We present a case study based on synthetic location tracking data where the derived synchronisation detection mechanism is applied.KeywordsLocation TrackingPerformance ModellingData MiningGeneralised Stochastic Petri Nets

Fine-Grained Parallel and Distributed Spatial Stochastic Simulation of Biological Reactions

Model-Generation of a Fictitious Clock Real-Time Logic Using Sharing Trees

In this paper, we introduce a real-time temporal probabilistic knowledge logic, called RATPK, which can express not only real-time temporal and probabilistic epistemic properties but also cooperation properties. It is showed that temporal modalities such as “always in an interval”, “until in an interval”, and knowledge modalities such as “knowledge in an interval”, “common knowledge in an interval” and “probabilistic common knowledge” can be expressed in such a logic. The model checking algorithm is given and a case is studied.

Increasing operating costs and decreasing net revenues have greatly underlined the importance of optimizing production operations. The development of automation systems in the Petroleum Industry has become important in uniting isolated production facilities to form integrated systems. This paper briefly traces the history and development of remote and computer control systems for gas and oil production. It also describes the development of the remote control and monitoring system installation at Union Oil onshore and offshore production facilities in East Kalimantan. Emphasis is placed more on the description of the remote process system monitoring and control in the Attaka field. The wireless communication and process control system are being used to transmit alarm and flow metering, emergency shutdown, and paging functions between five satellite wellhead platforms and production platform central monitoring system at the Attaka field. Each producing facility is designed to be compatible with remote supervisory control. To obtain this compatibility and a high degree of safety, conditions in each portion of the process system are monitored. Paralleling the development of automatic control techniques were computer applications. A simple computer system are being used to control and monitor three gas dehydration towers which comprise a portion of the Union LEX Plant operation at Santan onshore facility. Expectations and development of future systems and evaluation of past experience are discussed in the conclusion.

BackgroundCar accidents due to unexpected forward or backward runaway by older drivers are a serious social problem. Although the cause of these accidents is often attributed to stepping on the accelerator instead of the brake, it is difficult to induce such pedal application errors systematically with usual drive simulators. We developed a simple personal computer system that induces the pedal errors, and investigate the effects of age on the error behaviors.MethodsThe system consisted of a laptop computer and a three-pedal foot mouse. It measured response time, accuracy, and flexibility of pedal operation to visual stimuli. The system displayed two open circles on the computer display, lighting one of the circles in a random order and interval. Subjects were instructed to press the foot pedal with their right foot as quickly as possible when the circle was lit; the ipsilateral pedal to the lit circle in a parallel mode and the contralateral pedal in a cross mode. When the correct pedal was pressed, the light went off immediately, but when the wrong pedal was pressed, the buzzer sounded and the light remained on until the correct pedal was pressed. During a 6-min trial, the mode was switched between parallel and cross every 2 min. During the cross mode, a cross mark appears on the display. The pedal responses were evaluated in 52 subjects divided into young (20–29 years), middle-aged (30–64 years), and older (65–84 years) groups. Additionally, the repeatability of the pedal response characteristic indicators was examined in 14 subjects who performed this test twice.ResultsThe mean response time was 95 ms (17%) longer in the older group than in the young group. More characteristically, however, the older group showed 2.1 times more frequent pedal errors, fell into long hesitations (response freezing > 3 s) 16 times more often, and took 1.8 times longer period to correct the wrong pedal than the young groups. The indicators of pedal response characteristics showed within-individual repeatability to the extent that can identify the age-dependent changes.ConclusionsHesitations and extended error correction time can be associated with increased crash risk due to unexpected runaway by older drivers. The system we have developed may help to uncover and evaluate physiological characteristics related to crash risk in the elderly population.

In this paper we present a weighted fuzzy production rules method incorporating the concepts of local weight with fuzzy Petri net. An improved method to compute the fuzzy value of the gene expression levels of the consequent part and a better way to interpret the linguistic meaning of the consequent are proposed here. Our approach offers the advantages of enhancing the knowledge representation power of a fuzzy production rules, reducing the undesirable effects when computing the consequent part by the graphical representation of fuzzy Petri net. In the proposed model, a gene expression profile is first transformed into a mapping form and then the transformed data are mapped into the fuzzy inference system. We have built the fuzzy Petri net model and classified the input data in terms of time point and obtained the output data, so the system can be viewed as the two-input of five sets (very low, low, medium, high, and very high) and one output system.

In the process of software development, software testing is a huge project, and most of the software functionality testing is complex and repetitive, should to spend a lot of cost and manpower. Therefore, you can save a lot of manpower and costs, avoid human error and improve software quality if we can achieve automated testing. In the software development process, the application of model-driven developments has grown wider recently. The main concept is to fetch all of the significant properties referring to system design, and use formal or semi-formal model to describe system in different levels of abstraction. In this paper, we apply a tool based on high level Petri Net model of automated testing -- MISTA [1](Model based Integration and System Testing Automation) to automated generate test code for system. In this paper, through capture the information of the state machine diagram describes the behavior of the system in the Unified Modeling Language. Through the eXtensible Markup Language automation converted to High Level Petri Net test model, and then using automated test code generating software MISTA generation test cases and test code of system to achieve automated testing, and save the software required for testing a large number of human costs, and the software development process from design architecture to the software testing for a bridging.

Model checking is a systematic way of checking the absence of errors in a distributed system, i.e., assessing the functional requirements in a distributed system. However, there are certain challenges in this field, e.g., developing true abstract models and on their basis generalizing/guranteeing results, limited capacity of model checking tools and computational resources, identification of all requirements and their accurate specifications, etc. To understand and face such challenges, it is necessary to apply the prominent model checking techniques to different distributed systems designed for different communication models. In this thesis this challenge is accepted and resultantly encountered issues are discussed/addressed. The results reported are sufficient for advocating the need for applying model checking techniques as debugging. Therefore, we report bugs and the propose fixes but for ambiguous algorithms, we reconstruct them. We model check both fixed and reconstructed algorithms. We assess the following protocols: • Accelerated heartbeat protocols, • Consensus protocols in asynchronous distributed systems, • Group membership protocols and • Efficient algorithms to implement failure detectors in partially synchronous systems. We found that the accelerated heartbeat protocols proposed in [M.G. Gouda and T.M. McGuire, Accelerated Heartbeat Protocols, Proc. Of ICDCS’98], violated some natural and essential properties. We proved the results by giving counterexamples and developed the techniques to address the time-triggered events in mCRL2 and investigated the correct time bounds for all the protocols. Regarding consensus problem, we proved the correctness of the proposed algorithms where the failure detectors are unreliable (i.e., failure detectors may make mistakes). These algorithms are proposed in [T. Deepak Chandra and S. Toueg, Unreliable Failure Detectors for Reliable Distributed Systems, J. ACM, 1996 ]. For the group membership protocols proposed in [Y. Amir, D. Dolev, S. Kramer and D. Malki, Membership Algorithms for Multicast Communication Groups, Springer-Verlag, 1992], we found that the original specifications and the text explaining the protocols can be interpreted in different ways and even some natural interpretations contradict each other. Our formalization with respect to different interpretations showed the violation of claimed properties. So to resolve the ambiguities, we reconstructed the protocols and model-checked them. For analyzing the algorithms proposed in [M. Larrea, S. Arevalo and A.Fernndez, Efficient Algorithms to Implement Unreliable Failure Detectors in Partially Synchronous Systems, Proc. of DISC’99 ], we applied symmetry reduction techniques. We found that every algorithm encounters a deadlock if there is a bounded (yet arbitrarily large) buffer in the communication channel between a pair of nodes. We propose fixes for deadlock avoidance and model check the proposed algorithm in UPPAAL, FDR2 and MCRL2. We also present a comparison of these three tools for model checking one of the given four protocols.

A critical issue in patient planning is to determine whether the medical processes of a patient can be completed by a time constraint based on the available resources in hospitals. The problem is a Temporal Constraint Satisfaction Problem (TCSP). The objectives of this paper are to propose a viable and systematic approach to develop a distributed cooperative problem solver for TCSP and estimate the shortest and the longest completion time for handling a patient in the presence of uncertainty based on Multi-agent systems (MAS) architecture. Our approach combines MAS with a subclass of time Petri net (TPN) models to solve TCSP. Existing analysis methods of TPN based on state classes cannot be applied directly due to distributed architecture of MAS. In this paper, a temporal analysis method based on MAS architecture is proposed. Our temporal analysis method efficiently deduces the earliest and latest completion time of a patient based on interaction between agents.