Formal Model Research Articles

Applications of Artificial Intelligence in Power Systems

A continuous and reliable supply of electricity is necessary for the functioning of today’s modern and advanced society. Since the early to mid 1980s, most of the effort in power systems analysis has turned away from the methodology of formal mathematical modeling which came from the areas of operations research, control theory and numerical analysis to the less rigorous and less tedious techniques of artificial intelligence (AI). Power systems keep on increasing on the basis of geographical regions, assets additions, and introduction of new technologies in generation, transmission and distribution of electricity. AI techniques have become popular for solving different problems in power systems like control, planning, scheduling, forecast, etc. These techniques can deal with difficult tasks faced by applications in modern large power systems with even more interconnections installed to meet increasing load demand. The application of these techniques has been successful in many areas of power system engineering.

Development of Tools for Creating Parallel Data Mining Algorithms

The purpose of this work is to develop tools for building parallel data mining algorithms for execution in a distributed environment. A formal model of a data mining algorithm is proposed, characterized by a representation of the algorithm in the form of a set of independent operations that change the state of the knowledge model and structural blocks that allow modifying the structure of the algorithm, including for parallel execution. A method is proposed for creating parallel algorithms for data mining, in contrast to existing ones, using a decomposition of the algorithm into thread-safe functional blocks and allowing parallelization, both by changing the structure of the parallel algorithm and by configuring its execution. A methodology is proposed for parallelizing data mining algorithms, which differs from those known in that the proposed method of creating parallel data mining algorithms taking into account the characteristics of a distributed environment is applied to sequential analysis algorithms. To create parallel data mining algorithms, software templates built on the basis of a formal model and separating the implementation of the algorithm from distributed execution tools are proposed. A library of parallel data mining algorithms has been developed for execution in a distributed environment, including the proposed templates.

A theory of symbiotic corruption

Symbiotic corruption occurs when senior officials employ the symbiotic relationship with junior officials in corrupt activities, to induce them to participate in the political contest for power and political rents. This paper develops a formal theoretical model to analyze the mechanics and consequences of symbiotic corruption prevailing in weakly institutionalized societies. We find that in the presence of symbiotic corruption, political contests tend to arise when the initial distribution of political rents between rival factions is disproportional to their de facto political power. Anti-corruption by increasing the effective penalty or enhancing monitoring of corruption works differently, but both are surprisingly ineffective in a society plagued by symbiotic corruption. In an unbalanced political system, where the initial distribution of political rents is relatively disproportional, an increase in the effective penalty induces rival factions to reach a tacit collusion to maintain peace and leads to universal symbiotic corruption; a rise in monitoring efficiency decreases total corruption but inevitably increases symbiotic corruption. In a balanced political system, universal corruption always emerges, and anti-corruption only affects the transformation between symbiotic and individual corruptions. This study not only sheds light on the (in)effectiveness of conventional anticorruption measures in the presence of symbiotic corruption, but also provides a new perspective on the link between bureaucratic hierarchies, national-level power dynamics, and corruption.

Incorporating Real Option Value in Valuing Innovation: A Way Forward.

Considerable progress has been made in defining and measuring the real option value (ROV) of medical technologies. However, questions remain on how to estimate (1) ROV outside of life-extending oncology interventions; (2) the impact of ROV on costs and cost effectiveness; and (3) potential interactions between ROV and other elements of value. We developed a 'minimal modeling' approach for estimating the size of ROV that does not require constructing a full, formal cost-effectiveness model. We proposed a qualitative approach to assessing the level of uncertainty in the ROV estimate. We examined the potential impact of ROV on the incremental cost-effectiveness ratio as well as on the potential interactions between ROV and other elements of value. Lastly, we developed and presented a 15-item checklist for reporting ROV in value assessment. The minimal modeling approach uses estimates on the efficacy of current treatment and potential future innovation, as well as success rate and length of new treatment development, and can be applied to all types of ROV across disease areas. ROV may interact with the conventional value, value of hope, productivity effects, and insurance value. The impact of ROV on cost effectiveness can be evaluated via threshold analysis. The minimal modeling approach and the checklist developed in this paper simplifies and standardizes the estimation and reporting of ROV in value assessment. Systematically including and reporting ROV in value assessment will minimize bias and improve transparency, which will help improve the credibility of ROV research and acceptance by stakeholders.

ENDOR Spectroscopy Reveals the "Free" 5'-Deoxyadenosyl Radical in a Radical SAM Enzyme Active Site Actually is Chaperoned by Close Interaction with the Methionine-Bound [4Fe-4S]2+ Cluster.

1/2H and 13C hyperfine coupling constants to 5'-deoxyadenosyl (5'-dAdo•) radical trapped within the active site of the radical S-adenosyl-l-methionine (SAM) enzyme, pyruvate formate lyase-activating enzyme (PFL-AE), both in the absence of substrate and the presence of a reactive peptide-model of the PFL substrate, are completely characteristic of a classical organic free radical whose unpaired electron is localized in the 2pπ orbital of the sp2 C5'-carbon (J. Am. Chem. Soc. 2019, 141, 12139-12146). However, prior electron-nuclear double resonance (ENDOR) measurements had indicated that this 5'-dAdo• free radical is never truly "free": tight van der Waals contact with its target partners and active-site residues guide it in carrying out the exquisitely precise, regioselective reactions that are hallmarks of RS enzymes. Here, our understanding of how the active site chaperones 5'-dAdo• is extended through the finding that this apparently unexceptional organic free radical has an anomalous g-tensor and exhibits significant 57Fe, 13C, 15N, and 2H hyperfine couplings to the adjacent, isotopically labeled, methionine-bound [4Fe-4S]2+ cluster cogenerated with 5'-dAdo• during homolytic cleavage of cluster-bound SAM. The origin of the 57Fe couplings through nonbonded radical-cluster contact is illuminated by a formal exchange-coupling model and broken symmetry-density functional theory computations. Incorporation of ENDOR-derived distances from C5'(dAdo•) to labeled-methionine as structural constraints yields a model for active-site positioning of 5'-dAdo• with a short, nonbonded C5'-Fe distance (∼3 Å). This distance involves substantial motion of 5'-dAdo• toward the unique Fe of the [4Fe-4S]2+ cluster upon S-C(5') bond-cleavage, plausibly an initial step toward formation of the Fe-C5' bond of the organometallic complex, Ω, the central intermediate in catalysis by radical-SAM enzymes.

Towards a sociology of the future: An exploration in cognitive social theory

The aim of this article is a sociology of the future. Since the standard sociological practice of extrapolating from everyday semantics of the future and the time-consciousness of modernity is inadequate, an integrated cognitive sociological perspective allied to critical theory is introduced. It makes visible an essential dimension of social life that is either largely taken for granted, misunderstood or ignored by identifying different levels of cognitive structures organising minds, institutions and culture and following their role in societal dynamics. This perspective mediates the sociocultural and naturalistic approaches and introduces the concept of space-time. Centrally, a modal analysis of the key present-past-future sequence is presented, with the focus on the distinct status of the future. It is modally conceptualised, not simply in terms of possibility as is usual, but rather in terms of its modality as a necessary formal generic cultural model that makes the future in the first place conceivable and enables an orientation towards it to be established and maintained. The resulting cognitive sociological account offers a novel theoretical understanding of the future which could facilitate thorough sociological and critical theoretical analyses in the societal space-time field.

Abstract WMP94: Quantifying the Enhanced Clinical Benefit of Endovascular Thrombectomy Performed With Contemporary Workflows and Devices

Background: To date, the magnitude of the benefit of endovascular thrombectomy (EVT) over medical management in acute ischemic stroke has been quantified by the data of the five breakthrough RCTs of 2015. But contemporary EVT care has faster EVT workflow speeds and achieves higher rates of reperfusion. Updated quantitative estimates of the benefit of EVT vs medical management are needed. Methods: Contemporary FDA-monitored (TIGER/ARISE II) and pivotal (HERMES) EVT trial group differences were quantified for workflow speed (door-to-reperfusion time) and reperfusion rates (eTICI distribution). The projected effect of the faster workflow speed in further improving disability (mRS) outcomes were calculated using established HERMES treatment time-benefit models and the projected effect of higher reperfusion rates using established HERMES eTICI tier-specific outcomes. Results: Contemporary EVT trial groups, compared with pivotal trial EVT groups, had door-to-reperfusion 57 minutes faster (146m vs 89m), successful reperfusion 22.6% more often (71.0% vs 93.6%), and excellent reperfusion 45.1% more often (29.4% vs 74.5%). Figure 1 shows the resulting projected improvements in mRS distributions. For functional independence (mRS 0-2), outcome rates for MM vs pivotal EVT vs contemporary EVT were 25.2% vs 44.6% vs 74.5%. The number needed to treat (NNT) for 1 more patient to achieve functional independence improved from 5.2 to 2.5. For nondisabled outcome (mRS 0-1), outcome rates were 10.1% vs 27.4% vs 46.0%. The NNT for 1 more patient to achieve nondisabled outcome improved from 5.8 to 2.8. Over the entire mRS range, the NNT for 1 more patient to have less disability by at least one mRS level improved from 2.6 to 1.6. Conclusion: Formal modeling indicates that contemporary EVT confers substantially enhanced benefits over medical management. Among every 100 patients treated with EVT, 63 will have a less disabled long-term outcome including 36 more becoming disability-free.

Автоматизированная система оперативной регистрации технических изменений предприятия радиоэлектронной промышленности

The modern production of radio-electronic equipment is a typical example of a make-to-order type of production. With custom-made products, each order is a unique product. The repeatability of orders in the total volume of orders is quite small compared to new orders, which leads to a large increase in the product range. As a rule, manufactured products are complex, high-tech products that can have a large structure, consist of a large number of components, and have a complex manufacturing process. Thus, the implementation of the full cycle of production of products and the preparation of design documentation requires the support of specialized software. Given the complexity of finished products and the large number of participants involved in production activities, there is an exponential growth in the volume of information. Without the availability of up-to-date data and methods for quick decision making, the development and production process will not be effective. The issues of automating the tracking of operational changes in design documentation at all stages of the production of radio-electronic equipment are considered. Automated systems responsible for managing the life cycle of products are called PLM – Product Lifecycle Management – this is a strategy for the production of industrial products that manages the product at all stages of the life cycle. Existing commercial solutions in this area have redundant functionality and are difficult to integrate into the existing information space of the enterprise. Aim. Study of the process of registration of technical changes in design documentation. Methods. The article presents the process of implementing technical changes in the form of a formal model and a functional model for implementing the changelog using the IDEF0 notation. The architecture of the electronic log of operational registration of changes in the form of diagrams of UML graphic notation is presented. Results. Models for the development of an automated system for managing the electronic journal of operational registration of changes are proposed. The software implementation of the system for managing the electronic journal of operational registration of changes at a research and production enterprise is considered. Conclusion. The automated system proposed in the study allows in a short time to bring to the production shops of the enterprise information about the proposed changes in the design of a prototype product, stop production, take the necessary corrective actions and finalize the product with minimization of losses for the production of a new prototype.

Randomized Testing of RISC-V CPUs Using Direct Instruction Injection

TestRIG (Testing with Random Instruction Generation) is a testing framework for RISC-V implementations. The RISC-V community has standardized a formal model of the architecture in the Sail language <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> , giving a human-readable specification that can also be used for simulation and verification. The Sail language is designed for this purpose by allowing instruction semantics to be described conveniently (for example, by supporting variable bit-widths). Ideally, a RISC-V implementor could formally prove equivalence between their implementation and the Sail model, but proof tools are not yet sufficiently automated to be routinely used on the whole-processor level. They instead focus on equivalence between combinational logic functions, with verification of a full out-of-order microarchitecture remaining an open problem. As a pragmatic compromise, we use TestRIG to check equivalence between the model and an implementation by generating random instruction sequences, executing the same sequences on the model and the implementation under test, and comparing execution traces (tandem execution). This approach does not prove equivalence but can demonstrate divergence, and is usable in all stages of development.

A framework for embedded software portability and verification: from formal models to low-level code

AbstractPorting software to new target architectures is a common challenge, particularly when dealing with low-level functionality in drivers or OS kernels that interact directly with hardware. Traditionally, adapting code for different hardware platforms has been a manual and error-prone process. However, with the growing demand for dependability and the increasing hardware diversity in systems like the IoT, new software development approaches are essential. This includes rigorous methods for verifying and automatically porting Real-Time Operating Systems (RTOS) to various devices. Our framework addresses this challenge through formal methods and code generation for embedded RTOS. We demonstrate a hardware-specific part of a kernel model in Event-B, ensuring correctness according to the specification. Since hardware details are only added in late modeling stages, we can reuse most of the model and proofs for multiple targets. In a proof of concept, we refine the generic model for two different architectures, also ensuring safety and liveness properties. We then showcase automatic low-level code generation from the model. Finally, a hardware-independent factorial function model illustrates more potential of our approach.

Analysis of Accounting Information Systems on MSME Performance with Emotional Intelligence as Moderation

Good Emotional Intelligence (comprising self-awareness, motivation, and social skills) enables one to make appropriate decisions under a variety of circumstances. An organization's accounting information system is a device utilized to streamline the majority of business operations, regardless of the company's size (small, medium, or large). Due to the fact that MSMEs are a primary driver of economic expansion, the creation of new employment is crucial to their ability to make sound decisions.The analysis technique refers to a process of data analysis designed to yield information that can be utilized in this study. In order to facilitate researchers' comprehension of the data as a foundation for decision making, it is necessary to analyze the data for interpretation. The present study employed the Partial Least Squares (PLS) methodology is carried out in in three stages: Outer model analysis, Inner model analysis, Hypothesis testing. In accordance with the formal model, latent variables are defined explicitly as linear aggregates of observed variables or their indicators. In order to generate weight estimates for latent variable score components, the inner and outer model specifications are compared.Determine the impact of emotional intelligence (self-awareness, motivation, and social skills) on the performance of micro, small, and medium-sized enterprises (MSME) in relation to the implementation of accounting information systems. The primary data utilized in this study were collected through the distribution of questionnaires to MSME entrepreneurs in Jember Regency, who provided their responses. Clearly, the accounting information system plays a crucial role in the progress and growth of MSMEs. Emotional Intelligence has no appreciable impact on the efficacy of MSME businesses as it relates to accounting information systems. Nonetheless, Emotional Intelligence significantly impacts the business performance of SMEs.

Risk analysis and Fuzzy Based Model for the Estimation of Contingency Cost of Construction Projects

Abstract: Construction projects play a significant role in the economic and overall development of any country. They also involve significant financial investments, and costs related to risks are known as contingency costs. In order to determine the contingency cost, contractors must take project risks into account while estimating and projecting the cost of completion. Typically, contractors use their subjective judgment to estimate cost contingencies, ranging from 5 to 10% of the expected cost based on previous projects that are comparable to theirs. Nevertheless, this approach lacks a solid foundation and is difficult to support or defend. As a result, more impartial techniques for calculating project cost contingency have been offered. But the majority of approaches still depend on formal modeling techniques, which are difficult to implement in the construction sector. Based on risk analysis and the fuzzy expert system idea, this study suggests a flexible and logical way for estimating cost contingency that might take into account contractors' subjective assessment. The creation of a cost contingency model for Indian construction and infrastructure projects was the suggested technique in this study. A case study project is examined to show how the proposed model may be used. The validation result showed that, in comparison to real cost contingencies, the system's forecasts were within 20% of accuracy.

A refinement and abstraction method of the SPZN formal model for intelligent networked vehicles systems

A refinement and abstraction method of the SPZN formal model for intelligent networked vehicles systems

Digital Health Consent - for Better Interoperability and Consumer Control.

We present a framework for digital health consent in support of computable expression of medico-legal policies to govern consumer data sharing across providers. The approach is aligned with HL7 FHIR© standard, and is based on generic formalism for policy modelling, grounded in normative systems and deontic logic. We show the use of the framework for a clinical research scenario.

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Simulation models have been described using different perspectives, or worldviews. In the process interaction world view (PI), every entity is modeled by a sequence of actions describing its life cycle, offering a comprehensive model that groups the events involving each entity. In this paper we describe π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow, a formalism for representing hybrid models using a set of communicating processes. This set is dynamic, enabling processes to be created and destroyed at runtime. Processes are encapsulated into π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow base models and communicate through shared memory. π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow, however, can guarantee modularity by enforcing that models can only communicate by input and output interfaces. π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow extends current PI approaches by providing support for HyFlow concepts of sampling and dense (continuous) outputs, in addition to the more traditional event-based communication. Likewise HyFlow, π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow is a modeling & simulation formalism driven by expressiveness and performance analysis. We present π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow semantics, and several applications to illustrate π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}HyFlow ability to describe a diversity of systems.

Experimental investigation and thermodynamic assessment of the Na2O–Al2O3–CaO system

Thermodynamic investigation of the Na2O–Al2O3–CaO system plays an important role in the applications of HACs and refractory. However, the phase relationships in the Al2O3-rich corner of the isothermal section at 1473 K for this system are uncertain. Key experimental investigation was performed and an improved method was developed to prepare the samples. Four three-phase regions of NC3A8+CA2+β-Al2O3, CA2+CA6+β-Al2O3, CA6+β-Al2O3+Al2O3 and NC3A8+NA6+β-Al2O3 were confirmed by X-ray diffraction. The Na2O–Al2O3 system was reassessed by CALPHAD method and the Na2O–Al2O3–CaO system was optimized by using the ionic two-sublattice liquid model (Na+1,Al+3,Ca+2)P(AlO2−1,O−2)Q to describe the liquid phase and a sublattice compound energy formalism model (Na+1)2(Ca+2,Na+1)1(Al+3)4(O−2)8(Va,Na+1)1 to describe the ternary compound NCA2. A set of self-consistent thermodynamic parameters was finally obtained, satisfactorily reproducing the experimental data and predicting the liquidus projection and primary phase regions. The present thermodynamic investigation of the Na2O–Al2O3–CaO system contributes to compositional design in HACs and refractory.

QoE-aware budgeted edge data caching online: A primal–dual approach

Data caching has garnered significant attention in the field of edge computing due to the low-latency services offered by nearby edge servers. To efficiently utilize the data cache budget and ensure minimal data transmission latency, selecting appropriate edge servers for data caching is crucial. While the users’ Quality of Experience (QoE) plays a vital role in the service providers’ benefits, it has not been adequately considered in dynamic edge computing environments. This is primarily due to the non-linear correlation between QoE and Quality-of-Service (QoS), making cost-effective edge data caching challenging within the service provider’s limited budget. In this paper, we formally define the QoE-aware budgeted online edge data caching (QoE-BOEDC) problem, aiming to maximize the average user QoE while adhering to the service provider’s budget in a dynamic edge computing environment. Here, we formulate a formal optimization model for QoE-BOEDC, which can be proven to be NP-complete. Subsequently, we propose an online algorithm, PDOQ (Primal–Dual Optimization for QoE), based on the primal–dual technique, and theoretically establish its comparative ratio. Additionally, we conduct both small-scale and large-scale experimental tests, and the experimental results demonstrate that PDOQ significantly outperforms other representative algorithms.

Phase equilibria of advanced technology uranium silicide-based nuclear fuel

The phases in uranium-silicide binary system were evaluated in regards to their stabilities, phase boundaries, crystal structures, and phase transitions. The results from this study were used in combination with a well assessed literature to optimize the U-Si phase diagram using the CALPHAD method. A thermodynamic database was developed, which could be used to guide nuclear fuel fabrication, could be incorporated into other nuclear fuel thermodynamic databases, or could be used to generate data required by fuel performance codes to model fuel behavior in normal or off-normal reactor operations. The U3Si2 and U3Si5 phases were modeled using the Compound Energy Formalism model with 3 sublattices to account for the variation in composition. The crystal structure used for the USi phase was the tetragonal with an I4/mmm space. Above 450°C, the U3Si5 phase was modeled. The composition of the USi2 phase was adjusted to USi1.84. The calculated invariant reactions and the enthalpy of formation for the stoichiometric phases were in agreement with experimental data.

Descriptive design structure matrices for improved system dynamics qualitative modeling

AbstractQualitative modeling approaches can be useful in system information collection, model analysis, and formal model development. This is difficult when the number of elements and their interactions in the system is large. System dynamicists need additional tools and methods to conceptually model these large tightly coupled systems. We propose and test the Descriptive Design Structure Matrix (DDSM) as a qualitative system dynamics modeling tool and approach for systems with many elements and more interactions that can reasonably be modeled individually using traditional system dynamics methods. A DDSM consists of four parallel and internally consistent matrices that describe system interactions with binary relations, nontechnical text, technical text, and literature support. By including and documenting system information in multiple forms, DDSMs facilitate multiple stages of system dynamics modeling, improve modeler communication with system participants and domain experts, and improve model rigor. DDSM construction is described. A case study of the 2014 flooding in Kashmir is used to illustrate and test a DDSM and its application. Due to their compact format, DDSMs provide a useful visual communication aid, intuitive reasoning tool, and foundation for formal system dynamics modeling and analysis. © 2024 The Authors. System Dynamics Review published by John Wiley &amp; Sons Ltd on behalf of System Dynamics Society.

Modular rewritable Petri nets: An efficient model for dynamic distributed systems

Modern distributed systems are becoming pervasive and increasingly provided with adaptation, (self-)reconfiguration and mobility capability. On one side, to face the challenges of the highly dynamic environments where they are deployed. On the other side, to keep production/maintenance costs down. Therein lies the increasing demand for formal models encompassing all of these aspects (besides concurrency). Hardly any of the classical formalisms like Petri Nets, Automata, and Process Algebra, even though powerful, permits designers to easily specify dynamic structural changes to systems and evaluate their impact on system behaviour. That has led to several extensions of classical formal models (e.g., the Pi calculus or the Nets-within-Nets paradigm) rarely accompanied by suitable analysis techniques. A recent formalization of a class of Rewritable Place-Transition Nets (RwPT) in Maude has proved potentially convenient to specify dynamically reconfigurable systems. Concerning analogous proposals, the RwPT formalism provides more abstraction/flexibility in modelling and efficiency in analysis. Nevertheless, its ability to scale the size of distributed systems built of several similar (nested) components is limited.This paper presents a compositional approach to define large RwPT models in a typical algebraic way and to exploit the modular structure of models during the analysis: Symmetries are implicitly captured by composite node-labelling (reflecting the model's hierarchical structure) that is preserved by net rewrites. A distributed, gracefully degrading production system is used as a case study. Experimental evidence points out the dramatic impact of the approach against a non-modular one and the advantages over alternative techniques. Even if the emphasis is on state-space-based verification, the paper shows the convenience of combining it with structural analysis, which is typical of Petri nets as well. For that purpose, rewrite-rule abstractions are given in the form of guidelines.