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1

Dependability model of automated intelligent regenerative life support system for space missions

Kabashkin Igor, Glukhikh Sergey

International Journal of Electronics and Telecommunications

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2024

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Vol. 70, No. 1

39--44

EN

Long-duration human space missions require intelligent regenerative life support systems that can recycle resources and automatically manage failures. This paper explores using Petri nets to model the reliability and complex interactions of such closed-loop systems. An architecture consisting of primary systems, backups, and consumable reserves is outlined. The automation system that controls everything is described. Petri nets can capture concurrency, failure modes, redundancy, and dynamic behavior. A modular modeling methodology is presented to develop hierarchical Petri net models that scale in fidelity. Elementary fragments represent failures and redundancy. Subsystem modules can be substituted for more detailed models. Analysis and simulation assess system reliability and failure response. This supports designing ultra-reliable systems to safely sustain human life in space.

2

Generation of synchronizing state machines from a transition system: A region-based approach

Teren Viktor, Cortadella Jordi, Villa Tiziano

International Journal of Applied Mathematics and Computer Science

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2023

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Vol. 33, no. 1

133--149

EN

Transition systems (TSs) and Petri nets (PNs) are important models of computation ubiquitous in formal methods for modeling systems. A crucial problem is how to extract, from a given TS, a PN whose reachability graph is equivalent (with a suitable notion of equivalence) to the original TS. This paper addresses the decomposition of transition systems into synchronizing state machines (SMs), which are a class of Petri nets where each transition has one incoming and one outgoing arc. Furthermore, all reachable markings (non-negative vectors representing the number of tokens for each place) of an SM have only one marked place with only one token. This is a significant case of the general problem of extracting a PN from a TS. The decomposition is based on the theory of regions, and it is shown that a property of regions called excitation-closure is a sufficient condition to guarantee the equivalence between the original TS and a decomposition into SMs. An efficient algorithm is provided which solves the problem by reducing its critical steps to the maximal independent set problem (to compute a minimal set of irredundant SMs) or to satisfiability (to merge the SMs). We report experimental results that show a good trade-off between quality of results vs. computation time.

3

On the Complexity of Techniques That Make Transition Systems Implementable by Boolean Nets

Devillers Raymond, Tredup Ronny

Fundamenta Informaticae

|

2022

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Vol. 189, nr 3-4

261--296

EN

Let us consider some class of (Petri) nets. The corresponding Synthesis problem consists in deciding whether a given labeled transition system (TS) A can be implemented by a net N of that class. In case of a negative decision, it may be possible to convert A into an implementable TS B by applying various modification techniques, like relabeling edges that previously had the same label, suppressing edges/states/events, etc. It may however be useful to limit the number of such modifications to stay close to the original problem, or optimize the technique. In this paper, we show that most of the corresponding problems are NP-complete if the considered class corresponds to so-called flip-flop nets or some flip-flop net derivatives.

4

Performance enhancement of a solar water pumping system using a new three level parallel multicellular converter topology

Khaled Miloudi, Mabrouk Sellami, Tayeb Allaoui, Rafik Boukhlif, Mouloud Denai

Przegląd Elektrotechniczny

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2021

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R. 97, nr 12

7--13

EN

The use of phtovoltaic energy in water pumping is an economically viable and sustainable solution to rural communities without access to the electricity grid. The aim of this paper is to improve the performance of a phtovoltaic water pumping system by using a new converter structure based on three levels parallel multicell converter. This converter is controlled by two control loops, an external control based on the SMC and FLC MPPT algorithms and an internal control of the output branch current with the hybrid control based on the Petri nets. A comparative study between the boost converter and a three-levels parallel multicellular converter with the SMC and FLC MPPT has been made, which allows us to conclude that the new structure is more advantageous than the conventional structure especially. The boost gives rise to a wide band of strong power oscillations as well as the current and a voltage of PV, which translates into a high harmonic ratio with respect to the three-level parallel multicellular converter structure.

PL

Wykorzystanie energii fotowoltaicznej do pompowania wody jest ekonomicznie opłacalnym i zrównoważonym rozwiązaniem dla społeczności wiejskich bez dostępu do sieci elektrycznej. Celem tego artykułu jest poprawa wydajności fotowoltaicznego systemu pompowania wody poprzez zastosowanie nowej struktury konwertera opartej na trójpoziomowym równoległym konwerterze wieloogniwowym. Przetwornica ta jest sterowana przez dwie pętle sterowania, sterowanie zewnętrzne oparte na algorytmach SMC i FLC MPPT oraz sterowanie wewnętrzne prądu gałęzi wyjściowego ze sterowaniem hybrydowym opartym na sieciach Petriego. Przeprowadzono badanie porównawcze pomiędzy konwerterem boost a trójpoziomowym równoległym konwerterem wielokomórkowym z SMC i FLC MPPT, co pozwala stwierdzić, że nowa konstrukcja jest szczególnie korzystniejsza niż konstrukcja konwencjonalna. Wzmocnienie powoduje powstanie szerokiego pasma silnych oscylacji mocy oraz prądu i napięcia PV, co przekłada się na wysoki współczynnik harmonicznych w stosunku do trójpoziomowej równoległej struktury wielokomórkowej przetwornic.

5

Methods of process mining and prediction using deep learning

Cieplak Tomasz, Rymarczyk Tomasz, Kłosowski Grzegorz, Maj Michał, Pliszczuk Damian, Rymarczyk Paweł

Przegląd Elektrotechniczny

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2021

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R. 97, nr 3

146--149

EN

The first part of the article presents analytical methods to understand how processes (security or business) occur and function over time. The second part presents the concept of a predictive system using deep learning methods that would enable the prediction of subsequent operations or steps that are part of the process under consideration. The article was supplemented with a review of scientific publications related to the content and theoretical foundations were provided. The research was of an applied nature, therefore the considerations are based on the example of analysis and forecasts based on historical data contained in process logs.

PL

Pierwsza część artykułu przedstawia metody analityczne pozwalające zrozumieć, w jaki sposób procesy (dotyczące bezpieczeństwa lub biznesu) zachodzą i funkcjonują w czasie. W drugiej części przedstawiono koncepcję systemu predykcyjnego wykorzystującego metody głębokiego uczenia, które umożliwiałyby przewidywanie kolejnych operacji lub kroków wchodzących w skład rozważanego procesu. Uzupełnieniem artykułu był przegląd publikacji naukowych pod kątem merytorycznym oraz podano podstawy teoretyczne. Badania miały charakter aplikacyjny, dlatego rozważania opierają się na przykładzie analiz i prognoz opartych na danych historycznych zawartych w logach procesów.

6

Analysis of safeness in a Petri net-based specification of the control part of cyber-physical systems

Wojnakowski Marcin, Wiśniewski Remigiusz, Bazydło Grzegorz, Popławski Mateusz

International Journal of Applied Mathematics and Computer Science

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2021

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Vol. 31, no. 4

647--657

EN

The paper proposes an algorithm for safeness verification of a Petri net-based specification of the control part of cyber-physical systems. The method involves a linear algebra technique and is based on the computation of the state machine cover of a Petri net. Contrary to the well-known methods, the presented idea does not require obtaining all sequential components, nor the computation of all reachable states in the system. The efficiency and effectiveness of the proposed method have been verified experimentally with a set of 243 test modules (Petri net-based systems). The results of experiments show high efficiency of the proposed method since a solution has been found even for such nets where popular techniques are not able to analyze the safeness of the system. Finally, the presented algorithm is explained in detail using a real-life case-study example of the control part of a cyber-physical system.

7

Investigating Reversibility of Steps in Petri Nets

de Frutos Escrig David, Koutny Maciej, Mikulski Łukasz

Fundamenta Informaticae

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2021

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Vol. 183, nr 1-2

67--96

EN

In reversible computations one is interested in the development of mechanisms allowing to undo the effects of executed actions. The past research has been concerned mainly with reversing single actions. In this paper, we consider the problem of reversing the effect of the execution of groups of actions (steps). Using Petri nets as a system model, we introduce concepts related to this new scenario, generalising notions used in the single action case. We then present properties arising when reverse actions are allowed in place/transition nets (PT-nets). We obtain both positive and negative results, showing that allowing steps makes reversibility more problematic than in the interleaving/sequential case. In particular, we demonstrate that there is a crucial difference between reversing steps which are sets and those which are true multisets. Moreover, in contrast to sequential semantics, splitting reverses does not lead to a general method for reversing bounded PT-nets. We then show that a suitable solution can be obtained by combining split reverses with weighted read arcs.

8

Synthesis for Various Petri Net Classes with Union/Find

Wolf Karsten

Fundamenta Informaticae

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2019

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Vol. 169, nr 1-2

57--84

EN

We propose a new algorithmic approach for the synthesis of a Petri net from a transition system. It is first presented for a class of place/transition Petri nets we call Δ1-Petri nets. A Δ1-Petri net has an incidence matrix where entries have values 0, 1, and -1 only. The algorithm employs Tarjans union/find algorithm for managing sets of vertices. It requires just O(|V||T|) space where V is the set of vertices and T is the set of transition labels. Consequently, problem instances even beyond 1,000,000 vertices have a manageable memory footprint. Our results are experimentally validated using a prototype implementation. We further present ideas for adapting the method to various classes of Petri nets, including pure (loop-free), safe and k-bounded, ordinary nets as subclasses of Δ-1-Petri nets as well as an extension to Δk-Petri nets. This article is an extended version of [1].

9

Operational Semantics, Interval Orders and Sequences of Antichains

Janicki Ryszard, Koutny Maciej

Fundamenta Informaticae

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2019

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Vol. 169, nr 1-2

31--55

EN

A representation of interval orders by sequences of antichains is discussed, and its relationship to the Fishburn’s representation by sequences of the beginnings and endings of domain elements is analysed in detail. Moreover, an operational semantics based on sequences of maximal antichains is proposed and investigated for a general class of safe Petri nets with context arcs.

10

Co-Finiteness and Co-Emptiness of Reachability Sets in Vector Addition Systems with States

Jančar Petr, Leroux Jérôme, Sutre Grégoire

Fundamenta Informaticae

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2019

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Vol. 169, nr 1-2

123--150

EN

The boundedness problem is a well-known exponential-space complete problem for vector addition systems with states (or Petri nets); it asks if the reachability set (for a given initial configuration) is finite. Here we consider a dual problem, the co-finiteness problem that asks if the complement of the reachability set is finite; by restricting the question we get the co-emptiness (or universality) problem that asks if all configurations are reachable. We show that both the co-finiteness problem and the co-emptiness problem are exponential-space complete. While the lower bounds are obtained by a straightforward reduction from coverability, getting the upper bounds is more involved; in particular we use the bounds derived for reversible reachability by Leroux (2013). The studied problems were motivated by a result for structural liveness of Petri nets; this problem was shown decidable by Jančar (2017), without clarifying its complexity. The structural liveness problem is tightly related to a generalization of the co-emptiness problem, where the sets of initial configurations are (possibly infinite) downward closed sets instead of just singletons. We formulate the problems even more generally, for semilinear sets of initial configurations; in this case we show that the co-emptiness problem is decidable (without giving an upper complexity bound), and we formulate a conjecture under which the co-finiteness problem is also decidable.

11

Modelling of processes with use of process mining techniques

Brzychczy E., Napieraj A., Sukiennik M.

Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska

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2018

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z. 116

23--36

EN

The main purpose of the paper is presentation of new opportunities for process modelling. In the literature review section, Petri nets as one of the formal modelling notation of processes is highlighted and introduction of relatively young research discipline – process mining – is presented. One of the process mining tasks is process model discovery from event logs gathered in informatics systems in enterprise. In the article practical example of process model discovery with ProM software is given with use of real event log from Volvo IT Belgium. In conclusions further opportunities of process mining techniques in process management are emphasized.

12

Model agenta upostaciowionego bazujący na hierarchicznej sieci Petriego

Figat M., Zieliński C.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2018

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z. 196

395--406

PL

W ogólności system robotyczny projektowany jest jako pojedynczy agent upostaciowiony lub ich zestaw, ale ta praca koncentruje się na działaniu pojedynczego agenta. Agent upostaciowiony dekomponowany jest na współdziałające podsystemy. W dotychczasowych pracach działanie podsystemów opisywane było za pomocą hierarchicznych automatów skończonych, z których stanami były skojarzone operacje. W tym podejściu sposób komunikacji między podsystemami traktowany był jako zagadnienie implementacyjne. W artykule przedstawiono alternatywną metodę opisu agenta upostaciowionego za pomocą hierarchicznych sieci Petriego z dozorami. Hierarchiczna sieć powstaje poprzez przekształcenie automatu skończonego opisującego działanie podsystemu w sieć Petriego wyposażoną w podsieci definiujące zachowania. Wyspecyfikowanie zachowania wymaga natomiast wyjawienia za pomocą sieci Petriego wykorzystywanych modeli komunikacyjnych określających interakcje między podsystemami. Podejście wykorzystujące sieć Petriego umożliwia całościowe określenie działania agenta upostaciowionego w fazie specyfikacji.

EN

In general a robotic system is designed as a single embodied agent or a network of such agents. Nevertheless this work focuses on the activities of a single agent. An embodied agent is decomposed into interacting subsystems. Up till now the activities of subsystems have been specified by using hierarchic finite state automatons. Subsystem operations were associated with the states of those automatons. Communication between subsystems was treated as an implementation issue. This paper presents an alternative method of defining an embodied agent. A hierarchic Petri net with guards is used. A hierarchic net is the result of transformation of a finite state automaton describing the activities of a subsystem. Its subnets represent subsystem behaviours. Specification of behaviours requires the definition of inter-subsystem communication model, that also can be defined by a Petri net. Thus the resulting hierarchic Petri net specifies all of the activities of an embodied agent.

13

Process Modelling Based on Event Logs

Brzychczy E.

Multidisciplinary Aspects of Production Engineering

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2018

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Vol. 1, Iss. 1

385--392

EN

Process modelling is a very important stage in a Business Process Management cycle enabling process analysis and its redesign. Many sources of information for process modelling purposes exist. It may be an analysis of documentation related directly or indirectly to the process being analysed, observations or participation in the process. Nowadays, for this purpose, it is increasingly proposed to use the event logs from organization’s IT systems. Event logs could be analysed with process mining techniques to create process models expressed by various notations (i.e. Petri Nets, BPMN, EPC). Process mining enables also conformance checking and enhancement analysis of the processes. In the paper issues related to process modelling and process mining are briefly discussed. A case study, an example of delivery process modelling with process mining technique is presented.

14

Ore value chain modeling and cost analysis based on Petri nets

Ma Z., Hu N., Li G., Liu D., Pan T.

Gospodarka Surowcami Mineralnymi

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2018

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T. 34, z. 3

99--118

EN

At present, with the increase of production capacity and the promotion of production, the reserves of most mining enterprises under the original industrial indexes are rapidly consumed, and the full use of low-grade resources is getting more and more attention. If mining enterprises want to make full use of low-grade resources simultaneously and obtain good economic benefits to strengthening the analysis and management of costs is necessary. For metal underground mines, with the gradual implementation of exploration and mining projects, capital investment and labor consumption are dynamic and increase cumulatively in stages. Consequently, in the evaluation of ore value, we should proceed from a series of processes such as: exploration, mining, processing and the smelting of geological resources, and then study the resources increment in different stages of production and the processing. To achieve a phased assessment of the ore value and fine evaluation of the cost, based on the value chain theory and referring to the modeling method of computer integrated manufacturing open system architecture (CIMOSA), the analysis framework of gold mining enterprise value chain is established based on the value chain theory from the three dimensions of value-added activities, value subjects and value carriers. A value chain model using ore flow as the carrying body is built based on Petri nets. With the CPN Tools emulation tool, the cycle simulation of the model is carry out by the colored Petri nets, which contain a hierarchical structure. Taking a large-scale gold mining enterprise as an example, the value chain model is quantified to simulate the ore value formation, flow, transmission and implementation process. By analyzing the results of the simulation, the ore value at different production stages is evaluated dynamically, and the cost is similarly analyzed in stages, which can improve mining enterprise cost management, promote the application of computer modeling and simulation technology in mine engineering, more accurately evaluate the economic feasibility of ore utilization, and provide the basis for the value evaluation and effective utilization of low-grade ores.

PL

Obecnie wraz ze wzrostem zapotrzebowania na surowce mineralne, zasoby większości tych surowców podlegają bardzo szybkiemu sczerpaniu, a wykorzystanie zasobów o niskiej jakości jest brane pod uwagę coraz powszechniej. Jeśli przedsiębiorstwa wydobywcze chcą w pełni wykorzystać zasoby surowców mineralnych niskiej jakości i jednocześnie uzyskać dobre wyniki ekonomiczne, niezbędna jest szeroka analiza i zarządzanie kosztami. W przypadku podziemnych kopalń rud metali, przy stopniowej realizacji projektów poszukiwawczo-wydobywczych, nakłady inwestycyjne i nakłady pracy są dynamiczne i wzrastają stopniowo w realizowanych procesach. W związku z tym, w ocenie wartości rudy powinno się uwzględniać szereg procesów, takich jak: poszukiwanie, wydobycie, przeróbkę i hutnictwo, a następnie rozpatrywać przyrosty wartości i kosztów na poszczególnych etapach produkcji i przetwarzania. Aby osiągnąć etapową ocenę wartości rudy i dokładną ocenę kosztów, w oparciu o teorię łańcucha wartości, należy zastosować metodę komputerowego modelowania zintegrowanej produkcji otwartej architektury systemu (CIMOSA). Ramy analizy łańcucha wartości przedsiębiorstwa wydobywczego złota są ustalane z trzech ocen: wartości dodanej, wartości podmiotów i wartości nośników. Model łańcucha wartości wykorzystujący przepływ rudy zbudowany jest w oparciu o sieci Petriego. Symulacja cyklu modelu jest realizowana przez kolorowe sieci Petriego, które zawierają hierarchiczną strukturę. Przykładem jest wielkoskalowe przedsiębiorstwo wydobywcze złota, w którym model łańcucha wartości jest określany ilościowo w celu symulacji procesów tworzenia, przepływu, przeniesienia i realizacji. Analizując wyniki symulacji, wartość rudy na poszczególnych etapach produkcji jest oceniana dynamicznie, a koszty są również analizowane etapami, co może: poprawić zarządzanie kosztami przedsiębiorstw górniczych, promować zastosowanie modelowania komputerowego i technologii symulacji w inżynierii górniczej, bardziej dokładnie ocenić ekonomiczną wykonalność wykorzystania rudy i zapewnić podstawę do oceny wartości i efektywnego wykorzystania rud niskiej jakości.

15

Reversing Transitions in Bounded Petri Nets

Barylska K., Erofeev E., Koutny M., Mikulski Ł., Piątkowski M.

Fundamenta Informaticae

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2018

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Vol. 157, nr 4

341--357

EN

Reversible computation deals with mechanisms for undoing the effects of actions executed by a dynamic system. This paper is concerned with reversibility in the context of Petri nets which are a general formal model of concurrent systems. A key construction we investigate amounts to adding ‘reverse’ versions of selected net transitions. Such a static modification can severely impact on the behaviour of the system, e.g., the problem of establishing whether the modified net has the same states as the original one is undecidable. We therefore concentrate on nets with finite state spaces and show, in particular, that every transition in such nets can be reversed using a suitable set of new transitions.

16

Konstrukcja modeli barwnych sieci Petriego w celu intensyfikacji produkcji chemicznej

Trebuna P., Straka M., Rosova A., Malindzakova M., Makysova H.

Przemysł Chemiczny

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2016

|

T. 95, nr 7

1300--1303

PL

Barwne sieci Petriego zastosowano do zilustrowania warunków przebiegu procesu, w którym wytwarzano puszki i nakrywki polipropylenowe z powierzchniowymi nadrukami. Sieci te umożliwiły stworzenie szczegółowych modeli tego dość złożonego procesu przemysłowego. Analiza modeli pozwoliła na zrozumienie roli poszczególnych operacji i procesów jednostkowych oraz na określenie krytycznych węzłów na schemacie technologicznym, które normalnie pozostałyby niezauważone. W efekcie wykryto rezerwy produkcyjne i osiągnięto pewne oszczędności, poprawiając tym samym konkurencyjność przedsiębiorstwa.

EN

Colored Petri nets were used for modeling a process for com. prodn. of polypropylene cups and lids and colorprinting their surface. Use of the nets resulted in a better understanding of the individual operations and in an identification of weak points of the technol. process.

17

Ocena wskaźników niezawodnościowych stacji 110kV/SN i rozdzielni sieciowych SN w oparciu o metody analityczne oraz symulacyjne

Chojnacki A. Ł.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 7

180--185

PL

W artykule przedstawiona została analiza wskaźników niezawodnościowych stacji elektroenergetycznych 110kV/SN oraz rozdzielni sieciowych RS w oparciu o cząstkowe wskaźniki niezawodnościowe poszczególnych urządzeń oraz elementów tych stacji. Obliczenia zostały przeprowadzone w oparciu o metody analityczne oraz symulacyjne. Jako metodę analityczną zastosowano metodę minimalnych ścieżek niesprawności, natomiast metoda symulacyjna bazowała na teorii rozszerzonych sieci Petriego.

EN

The article presents an analysis of reliability indicators of 110kV / MV substations and switchgear station based on reliability partial indicators of the devices and elements of these stations. The calculations were carried out based on analytical and simulation methods. As an analytical method used method of minimal pathways malfunction, while the simulation method was based on the theory of extended Petri nets.

18

Synthesis of Petri net based model of a discrete event manufacturing system for nonlinear process plan

Słota A., Zając J., Uthayakumar M.

Management and Production Engineering Review

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2016

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Vol. 7, No. 2

62--72

EN

This work presents a modelling approach for nonlinear process plan (NLPP) implementation in discrete event manufacturing system (DEMS). NLPP is used for the building of the modular structure of an Object Observable Petri Net model of DEMS. The general capabilities of DEMS are defined by resources’ operation templates and the transition incidence relation. Based on system specification and NLPP executed in the system, the modular model of DEMS is defined. The required steps for constructing a modular model through the integration of resource models are presented. The proposed approach to modular modelling is illustrated by means of a sample DEMS and an example of NLPP.

19

On Liveness and Reversibility of Equal-Conflict Petri Nets

Hujsa T., Delosme J.-M., Munier-Kordon A.

Fundamenta Informaticae

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2016

|

Vol. 146, nr 1

83--119

EN

Weighted Petri nets provide convenient models of many man-made systems. Real applications are often required to possess the fundamental Petri net properties of liveness and reversibility, as liveness preserves all the functionalities (fireability of all transitions) of the system and reversibility lets the system return to its initial state (marking) using only internal operations. Characterizations of both behavioral properties, liveness and reversibility, are known for wellformed weighted Choice-Free and ordinary Free-Choice Petri nets, which are special cases of Equal-Conflict Petri nets. However, reversibility is not well understood for this larger class, where choices must share equivalent preconditions, although characterizations of liveness are known. In this paper, we provide the first characterization of reversibility for all live Equal-Conflict Petri nets by extending, in a weaker form, a known condition that applies to the Choice-Free and Free-Choice subclasses. We deduce the monotonicity of reversibility in the live Equal-Conflict class. We also give counter-examples for other classes where the characterization does not hold. Finally, we focus on well-formed Equal-Conflict Petri nets, for which we offer the first polynomial sufficient conditions for liveness and reversibility, contrasting with the previous exponential time conditions.

20

Sieci Petriego jako narzędzie intensyfikacji produkcji w przetwórstwie tworzyw sztucznych

Trebuna P., Straka M., Rosova A., Malindzakova M.

Przemysł Chemiczny

|

2015

|

T. 94, nr 9

1605-1608

PL

Przemysłowa produkcja polipropylenowych puszek i przykrywek przez wtryskiwanie została sformalizowana w postaci sieci Petriego i skutecznie wykorzystana do poprawy ekonomiki i konkurencyjności przedsiębiorstwa.

EN

Com. prodn. of polypropylene cans and lids by injection moulding was formalized as a Petri net and successfully evaluated to improve the economy and competitiveness of the company.