Timed Bounded Verification of Inclusion Based on Timed Bounded Discretized Language

2021 ◽  
pp. 1-28
Author(s):  
Ikhlass Ammar ◽  
Yamen El Touati ◽  
John Mullins ◽  
Moez Yeddes
Keyword(s):  
Timed Automata ◽  
Inclusion Problem ◽  
Countable Number ◽  
New Approach ◽  
Discretization Technique ◽  
The Common ◽  
Common Problems ◽  
Execution Times ◽  
Time Systems ◽  
Timed Automaton

The inclusion problem is one of the common problems in real-time systems. The general form of this problem is undecidable; however, the time-bounded verification of inclusion problem is decidable for timed automata. In this study, we propose a new discretization technique to verify the inclusion problem. The proposed technique is applied to a non-Zeno timed automaton with an upper bound that does not contain a non-reachable space for each transition. The new approach is based on the generation of timed bounded discretized language that represents an abstraction of timed words in the form of a set of a countable number of discrete timed words. A discrete timed word aggregates all timed words that share the same actions and their execution times that create the time continuous intervals. The lower and the upper bounds of an interval in a discrete timed word is defined by the minimum and maximum execution times associated to a given transition-run. In addition, we propose the verification schema of the inclusion between two timed bounded discretized languages generated by two non-Zeno timed automata.

MODELING AND ANALYSIS OF REAL-TIME SYSTEMS WITH MUTEX COMPONENTS

2012 ◽  
Vol 23 (04) ◽  
pp. 831-851 ◽  
Author(s):  
GUOQIANG LI ◽  
XIAOJUAN CAI ◽  
SHOJI YUEN
Keyword(s):  
Real Time ◽  
Timed Automata ◽  
Expressive Power ◽  
Behavioral Model ◽  
Parallel Composition ◽  
Real Time Systems ◽  
Modeling And Analysis ◽  
Compositional System ◽  
Time Systems ◽  
Timed Automaton

Timed automata are commonly recognized as a formal behavioral model for real-time systems. For compositional system design, parallel composition of timed automata as proposed by Larsen et al. [22] is useful. Although parallel composition provides a general method for system construction, in the low level behavior, components often behave sequentially by passing control via communication. This paper proposes a behavioral model, named controller automata, to combine timed automata by focusing on the control passing between components. In a controller automaton, to each state a timed automaton is assigned. A timed automaton at a state may be preempted by the control passing to another state by a global labeled transition. A controller automaton properly extends the expressive power because of the stack, but this can make the reachability problem undecidable. Given a strict partial order over states, we show that this problem can be avoided and a controller automaton can be faithfully translated into a timed automaton.

scholarly journals Model Checking via Reachability Testing for Timed Automata

1997 ◽  
Vol 4 (29) ◽  
Author(s):  
Luca Aceto ◽  
Augusto Burgueno ◽  
Kim G. Larsen
Keyword(s):  
Model Checking ◽  
Timed Automata ◽  
Reachability Problem ◽  
Liveness Properties ◽  
Time Logic ◽  
Definition Of ◽  
Reachability Testing ◽  
Time Systems ◽  
Timed Automaton ◽  
Theoretical Side

In this paper we develop an approach to model-checking for timed automata via reachability testing. As our specification formalism, we consider a dense-time logic with clocks. This logic may be used to express safety and bounded liveness properties of real-time systems. We show how to automatically synthesize, for every logical formula phi, a so-called test automaton T_phi in such a way that checking whether a system S satisfies the property phi can be reduced to a reachability question over the system obtained by making T_phi interact with S. <br />The testable logic we consider is both of practical and theoretical interest. On the practical side, we have used the logic, and the associated approach to model-checking via reachability testing it supports, in the specification and verification in Uppaal of a collision avoidance protocol. On the theoretical side, we show that the logic is powerful enough to permit the definition of characteristic properties, with respect to a timed version of<br />the ready simulation preorder, for nodes of deterministic, tau-free timed automata. This allows one to compute behavioural relations via our model-checking technique, therefore effectively reducing the problem of checking the existence of a behavioural relation among states of a timed automaton to a reachability problem.

scholarly journals Detection of Common Problems in Real-Time and Multicore Systems Using Model-Based Constraints

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Raphaël Beamonte ◽  
Michel R. Dagenais
Keyword(s):  
Real Time ◽  
System Analysis ◽  
Multicore Systems ◽  
New Approach ◽  
Model Driven ◽  
Model Based ◽  
Development Methodology ◽  
Multiple Processes ◽  
Common Problems ◽  
Time Systems

Multicore systems are complex in that multiple processes are running concurrently and can interfere with each other. Real-time systems add on top of that time constraints, making results invalid as soon as a deadline has been missed. Tracing is often the most reliable and accurate tool available to study and understand those systems. However, tracing requires that users understand the kernel events and their meaning. It is therefore not very accessible. Using modeling to generate source code or represent applications’ workflow is handy for developers and has emerged as part of the model-driven development methodology. In this paper, we propose a new approach to system analysis using model-based constraints, on top of userspace and kernel traces. We introduce the constraints representation and how traces can be used to follow the application’s workflow and check the constraints we set on the model. We then present a number of common problems that we encountered in real-time and multicore systems and describe how our model-based constraints could have helped to save time by automatically identifying the unwanted behavior.

scholarly journals Exact acceleration of complex real-time model checking based on overlapping cycle

2020 ◽  
Vol 6 ◽  
pp. e272
Author(s):  
Guoqing Wang ◽  
Lei Zhuang ◽  
Yu Song ◽  
Mengyang He ◽  
Ding Ma ◽  
...  
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Timed Automata ◽  
System Model ◽  
Real Time Systems ◽  
Time Model ◽  
Real Time System ◽  
Acceleration Method ◽  
Time Systems ◽  
Timed Automaton

When real-time systems are modeled as timed automata, different time scales may lead to substantial fragmentation of the symbolic state space. Exact acceleration solves the fragmentation problem without changing system reachability. The relatively mature technology of exact acceleration has been used with an appended cycle or a parking cycle, which can be applied to the calculation of a single acceleratable cycle model. Using these two technologies to develop a complex real-time model requires additional states and consumes a large amount of time cost, thereby influencing acceleration efficiency. In this paper, a complex real-time exact acceleration method based on an overlapping cycle is proposed, which is an application scenario extension of the parking-cycle technique. By comprehensively analyzing the accelerating impacts of multiple acceleratable cycles, it is only necessary to add a single overlapping period with a fixed length without relying on the windows of acceleratable cycles. Experimental results show that the proposed timed automaton model is simple and effectively decreases the time costs of exact acceleration. For the complex real-time system model, the method based on an overlapping cycle can accelerate the large scale and concurrent states which cannot be solved by the original exact acceleration theory.

Applying Possessive pronoun in Writing Sentences: Exploring Students’ Ability and Problems in a Mixed Method Study

2019 ◽  
Vol 1 (3) ◽  
pp. 79-83
Author(s):  
Eka Utami Putri ◽  
Syahdan Syahdan
Keyword(s):  
Mixed Method ◽  
Simple Random Sampling ◽  
Average Score ◽  
Mixed Method Study ◽  
Z Score ◽  
Possessive Pronoun ◽  
Efl Students ◽  
The Common ◽  
Common Problems ◽  
Essay Test

The purpose of this research was to find out the students' ability in applying Possessive pronoun in writing sentences and the problems encounter it.  This mixed method study employs an explanatory design to reveals it. 53 students out of 105 students from1st semester EFL students from one reputable University in Pekanbaru, Indonesia, were invited to this study. These 53 students were selected using simple random sampling and enrolled for an essay test and interview to see the students' ability and explaining the problems. The data analysis using SPSS showed that the average score of students was 52.98. Meanwhile for the median is 48, the mode is 20. The score of Standard Deviation is 27.93, Variance is 780.25, and Range is 84.  Z-Score was found 41.5%, which is means higher than average and 58.5% while, students' ability was indicated below the average. It showed that the students were low ability in applying possessive pronoun in writing sentences. The study also found the common problems, i.e., (1) students still mixed up between possessive pronoun and possessive adjectives. (2) students used the wrong pattern in using a possessive pronoun. (3) students did not understand clearly about a possessive pronoun, (4) experiencing difficulties in learning possessive pronoun. 

scholarly journals Common issues in the hetero-epitaxial seeding on SiC substrates in the sublimation growth of AlN crystals

2021 ◽  
Vol 127 (8) ◽  
Author(s):  
R. Radhakrishnan Sumathi
Keyword(s):  
Power Electronic ◽  
Etch Pit ◽  
Micro Hole ◽  
Wet Chemical ◽  
The Common ◽  
Common Problems ◽  
Hole Defects ◽  
Sublimation Growth ◽  
Impurity Elements ◽  
Very High

AbstractAluminium nitride (AlN) is a futuristic material for efficient next-generation high-power electronic and optoelectronic applications. Sublimation growth of AlN single crystals with hetero-epitaxial approach using silicon carbide substrates is one of the two prominent approaches emerged, since the pioneering crystal growth work from 1970s. Many groups working on this hetero-epitaxial seeding have abandoned AlN growth altogether due to lot of persistently encountered problems. In this article, we focus on most of the common problems encountered in this process such as macro- and micro-hole defects, cracks, 3D-nucleation, high dislocation density, and incorporation of unintentional impurity elements due to chemical decomposition of the substrate at very high temperatures. Possible ways to successfully solve some of these issues have been discussed. Other few remaining challenges, namely low-angle grain boundaries and deep UV optical absorption, are also presented in the later part of this work. Particular attention has been devoted in this work on the coloration of the crystals with respect to chemical composition. Wet chemical etching gives etch pit density (EPD) values in the order of 105 cm-2 for yellow-coloured samples, while greenish coloration deteriorates the structural properties with EPD values of at least one order more.

scholarly journals A New Approach to the PWM Modulation for the Multiphase Matrix Converters Supplying Loads with Open-End Winding

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 466
Author(s):  
Pawel Szczepankowski ◽  
Natalia Strzelecka ◽  
Enrique Romero-Cadaval
Keyword(s):  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Simulation Software ◽  
Common Mode ◽  
New Approach ◽  
Matrix Converters ◽  
Load Voltage ◽  
Common Mode Voltage ◽  
The Common ◽  
Open End Winding

This article presents three variants of the Pulse Width Modulation (PWM) for the Double Square Multiphase type Conventional Matrix Converters (DSM-CMC) supplying loads with the open-end winding. The first variant of PWM offers the ability to obtain zero value of the common-mode voltage at the load’s terminals and applies only six switches within the modulation period. The second proposal archives for less Total Harmonic Distortion (THD) of the generated load voltage. The third variant of modulation concerns maximizing the voltage transfer ratio, minimizing the number of switching, and the common-mode voltage cancellation. The discussed modulations are based on the concept of sinusoidal voltage quadrature signals, which can be an effective alternative to the classic space-vector approach. In the proposed approach, the geometrical arrangement of basic vectors needed to synthesize output voltages is built from the less number of vectors, which is equal to the number of the matrix converter’s terminals. The PWM duty cycle computation is performed using only a second-order determinant of the voltages coordinate matrix without using trigonometric functions. A new approach to the PWM duty cycles computing and the load voltage synthesis by 5 × 5 and 12 × 12 topologies has been verified using the PSIM simulation software.

scholarly journals Configurable verification of timed automata with discrete variables

2020 ◽  
Author(s):  
Tamás Tóth ◽  
István Majzik
Keyword(s):  
Timed Automata ◽  
Empirical Evaluation ◽  
Real Time Systems ◽  
Discrete Variables ◽  
Reachability Problem ◽  
Abstraction Refinement ◽  
Dependent Behavior ◽  
Wide Range ◽  
Time Systems ◽  
Lazy Abstraction

AbstractAlgorithms and protocols with time dependent behavior are often specified formally using timed automata. For practical real-time systems, besides real-valued clock variables, these specifications typically contain discrete data variables with nontrivial data flow. In this paper, we propose a configurable lazy abstraction framework for the location reachability problem of timed automata that potentially contain discrete variables. Moreover, based on our previous work, we uniformly formalize in our framework several abstraction refinement strategies for both clock and discrete variables that can be freely combined, resulting in many distinct algorithm configurations. Besides the proposed refinement strategies, the configurability of the framework allows the integration of existing efficient lazy abstraction algorithms for clock variables based on $${\textit{LU}}$$ LU -bounds. We demonstrate the applicability of the framework and the proposed refinement strategies by an empirical evaluation on a wide range of timed automata models, including ones that contain discrete variables or diagonal constraints.

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