Complex manufacturing systems are challenging to study because of the high level of information required and the inaccessibility of most of it. Their tractability is however essential for the efficiency of state-of-th...
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Complex manufacturing systems are challenging to study because of the high level of information required and the inaccessibility of most of it. Their tractability is however essential for the efficiency of state-of-the-art industries. This is particularly the case in the semiconductor industry that faces high mix and low volume conditions, and for which traditional methods fail to capture the high complexity and require continuous actions and corrections to adjust to heterogeneous toolsets and product-mix. We present the Concurrent WIP (CWIP), a new way of studying such systems at the level of a process-cluster by identifying each job's queue from its own perspective. CWIP is designed to be practical, with a low level of resource investments, yet informative. We explain how CWIP can be computed based on historical data and then used to derive capacity estimates and clearing functions without any assumptions on the system or on the form of the functions. In the process, we derive not only an average workload-dependent capacity, but also a confidence interval on this capacity. The relevance and efficiency of the proposed estimates are experimentally tested on a simulated system mimicking a small but complex process-cluster of the semiconductor industry. The estimates are used to predict WIP absorption times and we show how they characterize well not only the average behavior but also the full range of possible behaviors of the system. Finally, we discuss further applications of CWIP, that could be used to compute refined clearing functions or to monitor complex systems. Copyright (C) 2022 The Authors.
The protection against Advanced Persistent Threats (APTs) is an important topic in nuclear and industrial information technology security since the last decade. Nowadays steganography, i.e. information hiding techniqu...
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The protection against Advanced Persistent Threats (APTs) is an important topic in nuclear and industrial information technology security since the last decade. Nowadays steganography, i.e. information hiding techniques are increasingly used by attackers in order to operate without being detected. The usage of hidden channel communication in APTs creates a novel form of attack scenarios for which the current defense mechanisms are usually ineffective. In order to defend industrial control systems against those attacks, it is necessary to understand and comprehend the attacks. Thus, this paper presents how attack modelling based on the Lockheed Martin Cyber Kill Chain can be used to analyze hidden channel APT attack scenarios and how it can be used to elaborate defense mechanisms and to reveal attack indicators along all phases of those attack scenarios. Copyright (C) 2020 The Authors.
The objective of this paper is to propose an approach to decentralized robust stabilization with state-dependent supervisor for a class of nonlinear switched symmetric composite systems. The proposed methodology emplo...
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Theoretical study of complex systems receives more and more attention as most sciences broaden their perspectives. The paper first briefly overviews a few important complexity approaches, then it presents a triple-lev...
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Theoretical study of complex systems receives more and more attention as most sciences broaden their perspectives. The paper first briefly overviews a few important complexity approaches, then it presents a triple-level model for describing and analyzing collaborating enterprises. The environment is treated as a stochastic process, the core topology of the collaboration is represented by a graph and, finally, the dynamic behavior of collaborating enterprises is modeled as a Complex Adaptive System (CAS). complexity measures for the different sub-models are suggested, some complexity drivers are investigated and it is argued that the resulted model can be effectively analyzed by simulation.
In recent years, several approaches to the analysis of automation systems dependability through the application of formal verification techniques have been proposed. Much of the research has been concerned with the mo...
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In recent years, several approaches to the analysis of automation systems dependability through the application of formal verification techniques have been proposed. Much of the research has been concerned with the modelling languages used, and how best to express the automation systems, so that automated verification might be possible. Less attention, however, has been devoted to the process of writing properties that accurately capture the requirements that need verification. This is however a crucial aspect of the verification process. Writing appropriate properties, in a logic suitable for verification, is a skilful process, and indeed there have been reports of properties being wrongly expressed. In this paper we put forward a tool and a collection of property patterns that aim at providing help in this area.
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