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This position paper provides first, a literature survey of selected domains with significant contributions to simulation interoperability research, such as defense and healthcare simulation, including insights from academia and research organizations. Next, four main interoperability methods are reviewed, i.e., messages-oriented methods, use of information exchange models and common object models, and reference modeling, including ontological means. This review leads to the observation that successful approaches do not only rely on technical solutions but are also using conceptual alignment of the underlying models as well. The Levels of Conceptual Interoperability Model is revisited to consider how it contributed—and still contributes today—to reach meaningful interoperability between model-based solutions. Its descriptive and prescriptive use is discussed, and it is applied to the four methods to show its practical applicability. [ABSTRACT FROM AUTHOR]

Entropy can signify different things. For instance, heat transfer in thermodynamics or a measure of information in data analysis. Many entropies have been introduced, and it can be difficult to ascertain their respective importance and merits. Here, we consider entropy in an abstract sense, as a functional on a probability space, and we review how being able to handle the trivial case of non-interacting systems, together with the subtle requirement of extensivity, allows for a systematic classification of the functional form. [ABSTRACT FROM AUTHOR]

Despite best efforts, various challenges remain in the creation and maintenance processes of digital twins (DTs). One of those primary challenges is the constant, continuous and omnipresent evolution of systems, their user’s needs and their environment, demanding the adaptation of the developed DT systems. DTs are developed for a specific purpose, which generally entails the monitoring, analysis, simulation or optimisation of a specific aspect of an actual system, referred to as the actual twin (AT). As such, when the twin system changes, that is either the AT itself changes, or the scope/purpose of a DT is modified, the DTs usually evolve in close synchronicity with the AT. As DTs are software systems, the best practices or methodologies for software evolution can be leveraged. This paper tackles the challenge of maintaining a (set of) DT(s) throughout the evolution of the user’s requirements and priorities and tries to understand how this evolution takes place. In doing so, we provide two contributions: (i) we develop DarTwin , a visual notation form that enables reasoning on a twin system, its purposes, properties and implementation, and (ii) we introduce a set of architectural transformations that describe the evolution of DT systems. The development of these transformations is driven and illustrated by the evolution and transformations of a family home’s DT, whose purpose is expanded, changed and re-prioritised throughout its ongoing lifecycle. Additionally, we evaluate the transformations on a laboratory-scale gantry crane’s DT. [ABSTRACT FROM AUTHOR]

Mathematical modeling has become a major tool to guide the characterization and synthetic construction of cellular processes. However, models typically lose their capacity to explain or predict experimental outcomes as soon as any, even minor, modification of the studied system or its operating conditions is implemented. This limits our capacity to fully comprehend the functioning of natural biological processes and is a major roadblock for the de novo design of complex synthetic circuits. A common cause of this problem is that cell-to-cell variability creates couplings between single-cell circuits and population processes such as selection or growth. Altering the circuit may then have unforeseen consequences inside growing populations. Here we construct a yeast optogenetic differentiation system that exploits cell-to-cell variability to enable external control of the population composition. We show that a simple deterministic model can explain the dynamics of the core system. However, modifying the context of the circuit by expressing system components from plasmids leads to failure of model predictions. Subsequently, we deploy theory from stochastic chemical kinetics to construct models of the system's components that simultaneously track single-cell and population processes and demonstrate that this allows us to quantitatively predict emerging dynamics of the plasmid-based system without any adjustment of model parameters. We conclude that carefully characterizing the dynamics of cell-to-cell variability using appropriate modeling theory may allow one to unravel the complex interplay of stochastic single-cell and population processes and to predict the functionality of complex synthetic circuits in growing populations before the circuit is constructed. [ABSTRACT FROM AUTHOR]

Detailed maps of the molecular basis of the disease are powerful tools for interpreting data and building predictive models. Modularity and composability are considered necessary network features for large-scale collaborative efforts to build comprehensive molecular descriptions of disease mechanisms. An effective way to create and manage large systems is to compose multiple subsystems. Composable network components could effectively harness the contributions of many individuals and enable teams to seamlessly assemble many individual components into comprehensive maps. We examine manually built versions of the RAS–RAF–MEK–ERK cascade from the Atlas of Cancer Signalling Network, PANTHER and Reactome databases and review them in terms of their reusability and composability for assembling new disease models. We identify design principles for managing complex systems that could make it easier for investigators to share and reuse network components. We demonstrate the main challenges including incompatible levels of detail and ambiguous representation of complexes and highlight the need to address these challenges. [ABSTRACT FROM AUTHOR]

In this paper a passive integrator dedicated to input/output Hamiltonian systems approximation is presented. In a first step, a discrete Hamiltonian framework endowed with a Lie derivative-like formula is introduced. It is shown that the discrete dynamics encodes energy conservation and passivity. Additionally, the characterization of the discrete dynamics in terms of Dirac structure is shown to be invariant by interconnection. The class is thus composable: networked systems belong to the class. In a second step, the discrete dynamics is considered as a one-step integration method. The method is shown to be convergent and provides a discrete-time approximation of an input/output Hamiltonian system. Accordingly, the discrete dynamics inherits intrinsic energetic characteristics (storage function and dissipation rate) from the original system. The method is thus tagged as passive integrator. As an illustration, the closed-loop behavior of interconnected subsystems and the stabilization of a rigid body spinning around its center of mass are presented. [ABSTRACT FROM AUTHOR]

The last two decades witnessed the success of many efficient designs of concurrent data structures. A large set of them has a common base principle: each operation is split into a read-only traversal phase, which scans the data structure without locking or monitoring, and a read-write commit phase, which atomically validates the output of the traversal phase and applies the needed modifications to the data structure. In this paper we introduce Optimistic Transactional Boosting (OTB), an optimistic methodology for extending those designs in order to support the composition of multiple operations into one atomic execution by building a single traversal phase and a single commit phase for the whole atomic execution. As a result, OTB-based data structures are optimistic and composable . The former because they defer any locking and/or monitoring to the commit phase of the entire atomic execution; the latter because they allow the execution of multiple operations atomically. Additionally, in this paper we provide a theoretical model for analyzing OTB-based data structures and proving their correctness. In particular, we extended a recent approach that models concurrent data structures by including the two notions of optimism and composition of operations. [ABSTRACT FROM AUTHOR]

The composability of simulation models is the core of research of the theory and method of composable simulation. Based on the composition-oriented M&S framework, the significance of the "context" to composability evaluation was described. Through the formal definitions of the application context, the model context and their relationship with the composability, the validity of composability is to determine whether the model context of simulation models and their composition is true under the restriction of the application context, therefore, based on the interface pruning and behavior pruning in the model context, the conditions of model composition which meet the application requirements were put forward, and then the criteria for the four IO levels were induced. The criteria not only help to clearly describe the research level and content of composability evaluation, but also help to carry out the engineering practice of composable design and simulation models' maturity. [ABSTRACT FROM AUTHOR]

Service discovery is a hot topic in the field of services computing. As compared to classic methods that focus on service contents, this paper presents a new approach from the viewpoint of interconnectivity, to find important services and the corresponding composable services based on previous records of service composition. Empirical results show that (1) 95% of mashups on the website ProgrammableWeb contain important Web APIs discovered by our approach, and (2) the rate of success for analyzing the composability of a given set of Web APIs runs up to 98%. Thus, this approach would be helpful for effectively searching and recommending services on the Internet. [ABSTRACT FROM AUTHOR]

Triple-modular-redundant applications are widely used for fault-tolerant safety–critical computation. They have strict timing requirements for correct operation. We present an architecture which provides composability and mixed-criticality to support integration and to ease certification of such safety–critical applications. In this architecture, an additional layer is required for the sharing/partitioning of resources. This potentially jeopardizes the synchronization necessary for the triple-modular-redundant applications. We investigate the effects of different (unsynchronized) scheduling methods for the resource-sharing layer in this architecture and conclude that an out-of-the-box solution, which guarantees the technical separation between applications with fast reaction time requirements is only feasible when executing at most one instance of a triple-modular-redundant application per CPU-core for single and multi-core CPUs. Only when accepting changes in the applications or the applications’ synchronization mechanisms, are more flexible solutions with good performance and resource utilization available. [ABSTRACT FROM AUTHOR]

Modeling & Simulation (M&S) is making successful contributions to different areas in industry and academia. However, there are certain key issues that are preventing the field from addressing larger domains and from achieving wide-scale impact. Formulating these as grand challenges arguably focuses attention on these key issues and may bring a critical mass of effort to bear that could result in a major leap forward. This article is one of several concurrent activities aimed at reinvigorating the debate on grand challenges in M&S. These grand challenges include Big Simulation, human behavior, composability, cloud-based M&S, reproducibility in M&S research and the democratization of M&S. Two themes emerge: the need for large-scale cloud-based cyberinfrastructures for M&S and the democratized access to M&S and its outputs. [ABSTRACT FROM AUTHOR]

We present Abstract (ABortable STate mAChine replicaTion), a new abstraction for designing and reconfiguring generalized replicated state machines that are, unlike traditional state machines, allowed to abort executing a client's request if "something goes wrong." Abstract can be used to considerably simplify the incremental development of efficient Byzantine faulttolerant state machine replication (BFT) protocols that are notorious for being difficult to develop. In short, we treat a BFT protocol as a composition of Abstract instances. Each instance is developed and analyzed independently and optimized for specific system conditions. We illustrate the power of Abstract through several interesting examples. We first show how Abstract can yield benefits of a state-of-the-art BFT protocol in a less painful and errorprone manner. Namely, we develop AZyzzyva, a new protocol that mimics the celebrated best-case behavior of Zyzzyva using less than 35% of the Zyzzyva code. To cover worst-case situations, our abstraction enables one to use in AZyzzyva any existing BFT protocol. We then present Aliph, a new BFT protocol that outperforms previous BFT protocols in terms of both latency (by up to 360%) and throughput (by up to 30%). Finally, we present R-Aliph, an implementation of Aliph that is robust, that is, whose performance degrades gracefully in the presence of Byzantine replicas and Byzantine clients. [ABSTRACT FROM AUTHOR]

The adoption of Networks-on-Chip (NoCs) as the communication infrastructure for complex integrated systems is a fact, and has been promoted by the growing number of processing elements integrated in current MPSoCs. These are designed to execute several applications in parallel, with different communication requirements and distinct levels of required quality of service. To meet these restrictions, most designs customize the MPSoC at design time, using specific NoC communication services as adaptive routing algorithms, priorities, and connections. However, MPSoCs are increasingly used in embedded systems, where new applications may be added at runtime, characterizing dynamic workload scenarios. Such scenarios require adaptability at runtime, with applications having the possibility to select the most appropriate communication service according to their respective requirements. The goal of the present work is to link the hardware level of NoCs to the MPSoC application level, proposing the development of a communication API that exposes the communication services offered by the NoC to the application developer. Executing real and synthetic applications in two different MPSOCs, and using four different NoC communication services enabled to demonstrate the efficiency of the proposed approach to meet applications requirements. [ABSTRACT FROM PUBLISHER]

Abstract: The European ARTEMIS ACROSS project aims to overcome the limitations of existing Multi-Processor Systems-on-a-Chip (MPSoC) architectures with respect to safety–critical applications. MPSoCs have a tremendous potential in the domain of embedded systems considering their enormous computational capacity and energy efficiency. However, the currently existing MPSoC architectures have significant limitations with respect to safety–critical applications. These limitations include difficulties in the certification process due to the high complexity of MPSoCs, the lacking temporal determinism and problems related to error propagation between subsystems. These limitations become even more severe, when subsystems of different criticality levels have to be integrated on the same computational platform. Examples of such mixed-criticality integration are found in the avionics and automotive industry with their desire to integrate safety–critical, mission critical and non-critical subsystems on the same platform in order to minimize size, weight, power and cost. The main objective of ACROSS is to develop a new generation of multi-core processors designed specially for safety–critical embedded systems; the ACROSS MPSoC. In this paper we will show how the ACROSS MPSoC overcomes the limitations of existing MPSoC architectures in order to make the multi-core technology available to the safety–critical domain. The proposed approach enables efficient certification, complexity management, mixed-criticality integration and the development of temporally deterministic hard real-time systems. The major technological innovations of ACROSS are an increased level of design abstraction, message-based interfaces for core-to-core communication and reliable fault and error containment established by a novel time-triggered network-on-chip. The achieved results comprise, a novel architecture for MPSoCs, a prototype implemenation on FPGA technology as a proof-of-concept, a comprehensive set of middle-ware services and multiple demonstrators that show the benefits of the ACROSS Architecture in real world industrial applications. [Copyright &y& Elsevier]

With the prevalence of net-centric environments, Service-Oriented Architectures (SOAs) have emerged as a paradigm that greatly impacts the modeling and simulation (M&S) community. This paper has two interrelated goals. The first is to give a comprehensive review of various service-oriented simulation frameworks to help researchers select the appropriate one for their specific purpose. The second goal is to combine the common features derived from the review into one unifying framework that can describe and prescribe various specific approaches. The focus of this paper is on the common functionalities of service-oriented simulations reflected in the review and unifying framework. In particular, we emphasize the way SOAs and M&S are combined, and the interoperability and composability challenges of distributed M&S services. We describe some fundamental concepts first. Then we present a comprehensive survey of several classical frameworks, including formalism-based, model-driven, interoperability protocol based, eXtensible Modeling and Simulation Framework (XMSF), Open Grid Services Architecture (OGSA) based, and ontology-driven frameworks. Based on the review, we propose a novel three-dimensional reference model that can unify the ad hoc approaches into a common framework. The model can be used as a guideline or an analytic means to find potential and possible future directions. In particular, the model inspects the crossover between the disciplines of M&S, service-orientation, and software/systems engineering. Based on the model, we present a detailed comparison of the reviewed frameworks. Finally the significance of the paper is discussed and future directions are recommended. [ABSTRACT FROM PUBLISHER]

In this paper, we explore how component-based Modeling and Simulation can benefit from the Levels of Conceptual Interoperability Model, which is a three-level interoperation model, by proposing an ontology-based and domain-independent approach supporting composability (conceptual level) and interoperability (during execution). The proposed approach is in accordance with three standards: High-level Architecture for the implementation level, Base Object Model for the conceptual level, and meta object facility for the knowledge level. We apply this approach in implementing a normalized large-scale rescue management system by reusing existing agent-based simulators. The proposed approach is useful for modeling complex systems and facilitating interoperation between models (conceptual level) and between simulators (implementation level). [ABSTRACT FROM PUBLISHER]

• Novel high molecular weight 100% bio-based random aliphatic-aromatic copolymers of PTF containing different amounts of sebacic acid were synthesized by eco-friendly polycondensation in the melt. • Low amounts of PTSeb comonomeric units significantly modify PTF thermal, mechanical and barrier properties and render the final material compostable. • PTF15PTSeb copolyester exhibited superior gas barrier properties to O 2 and CO 2 , and temperature induced shape memory behavior, which foreshadows possible new applications, including as example biomedical ones, for these new PTF copolymers beyond food packaging ones. Highly promising fully biobased random copolyesters, poly(trimethylene 2,5-furandicarboxylate- co -trimethylene sebacate) (PTFcoPTSeb), were synthesized by using bio derived 1,3-propanediol, dimethyl ester of 2,5- furandicarboxylic acid, and sebacic acid, through eco-friendly polycondensation in the melt. Copolymers with high molecular weight containing 5, 15, 25 mol % of PTSeb were obtained, and their chemical structure confirmed by 1H NMR and FTIR spectroscopy. The thermal, tensile and gas barrier properties and composability were studied in relation to the copolymer supramolecular structure. As expected, introduction of PTSeb co-units results in lowering of glass transition temperature of copolymers and improves their flexibility. Besides, all copolymers showed outstanding gas barrier properties to O 2 and CO 2 , with copolymer containing 15 mol % of PTSeb showing exceptional gas barrier properties, better than those of PTF and comparable to those of EVOH, currently used in multilayer packaging films. The same copolymer exhibited temperature induced shape memory behaviour. It was found that low amounts (15-25 mol %) of PTSeb in copolymer significantly modifies PTF thermal, mechanical and barrier properties and renders the final material compostable. Copolyesters containing 15 and 25 mol % of PTSeb can compete in some applications with commercially available compostable Ecoflex® polymer, but with markedly improved barrier properties. [ABSTRACT FROM AUTHOR]

Abstract: Modern day applications require use of multi-processor systems for reasons of performance, scalability and power efficiency. As more and more applications are integrated in a single system, mapping and analyzing them on a multi-processor platform becomes a multi-dimensional problem. Each possible set of applications that can be concurrently active leads to a different use-case (also referred to as scenario) that the system has to be verified and tested for. Analyzing the feasibility and resource utilization of all possible use-cases becomes very demanding and often infeasible. Therefore, in this paper, we highlight this issue of being able to analyze applications in isolation while still being able to reason about their overall behavior – also called composability. We make a number of novel observations about how arbitration plays an important role in system behavior. We compare two commonly used arbitration mechanisms, and highlight the properties that are important for such analysis. We conclude that none of these arbitration mechanisms provide the necessary features for analysis. They either suffer from scalability problems, or provide unreasonable estimates about performance, leading to waste of resources and/or undesirable performance. We further propose to use a Resource Manager (RM) to ensure applications meet their performance requirements. The basic functionalities of such a component are introduced. A high-level simulation model is developed to study the performance of RM, and a case study is performed for a system running an H.263 and a JPEG decoder. The case study illustrates at what granularity of control a resource manager can effectively regulate the progress of applications such that they meet their performance requirements. [Copyright &y& Elsevier]

Abstract: We define reactive simulatability for general asynchronous systems. Roughly, simulatability means that a real system implements an ideal system (specification) in a way that preserves security in a general cryptographic sense. Reactive means that the system can interact with its users multiple times, e.g., in many concurrent protocol runs or a multi-round game. In terms of distributed systems, reactive simulatability is a type of refinement that preserves particularly strong properties, in particular confidentiality. A core feature of reactive simulatability is composability, i.e., the real system can be plugged in instead of the ideal system within arbitrary larger systems; this is shown in follow-up papers, and so is the preservation of many classes of individual security properties from the ideal to the real systems. A large part of this paper defines a suitable system model. It is based on probabilistic IO automata (PIOA) with two main new features: One is generic distributed scheduling. Important special cases are realistic adversarial scheduling, procedure-call-type scheduling among colocated system parts, and special schedulers such as for fairness, also in combinations. The other is the definition of the reactive runtime via a realization by Turing machines such that notions like polynomial-time are composable. The simple complexity of the transition functions of the automata is not composable. As specializations of this model we define security-specific concepts, in particular a separation between honest users and adversaries and several trust models. The benefit of IO automata as the main model, instead of only interactive Turing machines as usual in cryptographic multi-party computation, is that many cryptographic systems can be specified with an ideal system consisting of only one simple, deterministic IO automaton without any cryptographic objects, as many follow-up papers show. This enables the use of classic formal methods and automatic proof tools for proving larger distributed protocols and systems that use these cryptographic systems. [Copyright &y& Elsevier]

We propose a composability model to ascertain that Web services can safely be combined, hence avoiding unexpected failures at runtime. Composability is checked through a set of rules organized into four levels: syntactic, static semantic, dynamic semantic, and qualltative levels. We introduce the concepts of composability degree and τ-composability to cater for partial and total composability. We also propose a set of algorithms for checking composability. Finally, we conduct a performance study (analytical and experimental) of the proposed algorithms. [ABSTRACT FROM AUTHOR]

We consider the thermodynamic stability conditions (TSC) on the Boltzmann entropies generalized by Tsallis’ q- and Kaniadakis’ κ-deformed logarithmic functions. It is shown that the corresponding TSCs are not necessarily equivalent to the concavity of the generalized Boltzmann entropies with respect to internal energy. Nevertheless, both the TSCs are equivalent to the positivity of standard heat capacity. [Copyright &y& Elsevier]

The thermodynamic stability conditions (TSC) of nonadditive and composable entropies are discussed. Generally the concavity of a nonadditive entropy with respect to internal energy is not equivalent to the corresponding TSC. It is shown that both the TSC of Tsallis'entropy and that of the ?-generalized Boltzmann entropy are equivalent to the positivity of the standard heat capacity. [ABSTRACT FROM AUTHOR]

It is shown how, among a class of generalized entropies, the Tsallis entropy can uniquely be identified by the principles of thermodynamics, the concept of stability, and the axiomatic foundations. [ABSTRACT FROM AUTHOR]

Time-triggered (TT) distributed real-time computing systems are moving into the mainstream for the implementation of safety-critical applications in the aerospace and automotive sectors. This paper introduces the basic principles of a TT real-time computing system, and elaborates on the benefits that can be gained from the availability of a global time base in general, and in specifying the linking interfaces of components in particular. It describes the concept of a temporal firewall that forms a fully specified operational interface of a component. The most important contribution of the TT-paradigm is the establishment of a sound basis for the composability of a design and the reuse of components in distributed real-time systems. [Copyright &y& Elsevier]

ASTRAL is a formal specification language for realtime systems. It is intended to support formal software development and, therefore, has been formally defined. The structuring mechanisms in ASTRAL allow one to build modularized specifications of complex systems with layering. A realtime system is modeled by a collection of state machine specifications and a single global specification. This paper discusses the rationale of ASTRAL's design. ASTRAL's specification style is illustrated by discussing a telephony example. Composability of one or more ASTRAL system specifications is also discussed by the introduction of a composition section, which provides the needed information to combine two or more ASTRAL system specifications. [ABSTRACT FROM AUTHOR]

A permutation class C is said to be splittable if there exist two proper subclasses A , B ⊊ C such that any σ ∈ C can be red–blue colored so that the red (respectively, blue) subsequence of σ is order isomorphic to an element of A (respectively, B). The class C is said to be composable if there exists some number of proper subclasses A 1 , ... , A k ⊊ C such that any σ ∈ C can be written as α 1 ∘ ⋯ ∘ α k for some α i ∈ A i . We answer a question of Karpilovskij by showing that there exists a composable permutation class that is not splittable. We also give a condition under which an infinite composable class must be splittable. [ABSTRACT FROM AUTHOR]

• Herein, we reviewed the potential of bio-based food packaging materials as an alternative to petro- materials. • Effective deployment of suitable packaging material is a growing concern. • The broader applied spectrum of polymeric materials is discussed with suitable examples. In food industry, a growing concern is the use of suitable packaging material (i.e., biodegradable coatings and films) with enhanced thermal, mechanical and barrier characteristics to prevent from contamination and loss of foodstuff. Biobased polymer resources can be used for the development of biodegradable bioplastics. To achieve this goal, biopolymers should be economic, renewable and abundantly available. Bioplastic packaging materials based on renewable biomass could be used as sustainable alternative to petrochemically-originated plastic materials. This review summarizes the recent advancements in biopolymer-based coatings and films for active food packaging applications. Microbial polymers (PHA and PLA), wood-based polymers (cellulose, hemicellulose, starch & lignin), and protein-based polymers (gelatin, keratin, wheat gluten, soy protein and whey protein isolates) were among the materials most widely exploited for the development of smart packaging films. These biopolymers are able to synthesize coatings and films with good barrier properties against food borne pathogens and the transport of gases. Biobased reinforcements e.g., plant essential oils and natural additives to bioplastic films improve oxygen barrier, antibacterial and antifungal properties. To induce the desired functionality the simultaneous utilization of different synthetic and biobased polymers in the form of composites/blends is also an emerging area of research. Nanoscale reinforcements into bioplastic packaging have also been reported to improve packaging characteristics ultimately increasing food shelf life. The development of bioplastic/biocomposite and nanobiocomposites exhibits high potential to replace nonbiodegradable materials with characteristics comparable to fossil-based plastics, additionally, giving biodegradable and compostable characteristics. The idea of utilization of renewable biomass and the implications of biotechnology can firstly reduce the burden from fossil-resources, while secondly promoting biobased economy. [ABSTRACT FROM AUTHOR]