A significant barrier to the combined use of simulation and AI techniques such as Machine Learning (ML) are that developers have differing backgrounds and use different tools. In particular simulation model developers may lack expertise in the software tools and coding abilities needed for the development of ML algorithms. In order to bridge this gap this article presents a discrete-event simulation (DES) that incorporates the use of a reinforcement learning (RL) algorithm which determines an approximate best route for robots in a factory moving from one physical location to another whilst avoiding collisions with fixed barriers. The study shows how the object modelling and graphical facilities of the Simio commercial off-the-shelf (COTS) DES software package enables an RL capability without the need to use program code or require an interface with external RL software.
This paper reports on the co-simulation of a team of robots deployed in an exploration task, coordinated by a bio-inspired exploration algorithm. The co-simulation integrates the high-level exploration algorithm with detailed implementations of the robot controllers and kinematic models. Co-simulation results are used to find and correct mismatches between submodels.
This paper proposes a three-dimensional (3D) communication channel model for an indoor environment considering the effect of the Hypersurface. The Hypersurface is a software controlled intelligent metasurface, which can be used to manipulate electromagnetic waves, as for example for nonspecular reflection and full absorption. Thus it can control the impinging rays from a transmitter towards a receiver location in both LOS and NLOS paths, e.g. to combat distance and improve wireless connectivity. We focus on the 60 GHz mmWave frequency band due to its increasing significance in 5G/6G networks and evaluate the effect of Hypersurface in an indoor environment in terms of attenuation coefficients related to the Hypersurface reflection and absorption functionalities, using CST simulation, a 3D electromagnetic simulator of high frequency components. To highlight the benefits of Hypersurface coated walls versus plain walls, we use the derived Hypersurface 3D channel model and a custom 3D ray-tracing simulator for plain walls considering a typical indoor scenario for different Tx-Rx location and separation distances.
In this paper, we simulated a distributed, cooperative path planning technique for multiple drones (~200) to explore an unknown region (~10,000 connected units) in the presence of obstacles. The map of an unknown region is dynamically created based on the information obtained from sensors and other drones. The unknown area is considered a connected region made up of hexagonal unit cells. These cells are grouped to form larger cells called sub-areas. We use long range and short range communication. The short-range communication within drones in smaller proximity helps avoid re-exploration of cells already explored by companion drones located in the same subarea. The long-range communication helps drones identify next subarea to be targeted based on weighted RNN (Reverse nearest neighbor). Simulation results show that weighted RNN in a hexagonal representation makes exploration more efficient, scalable and resilient to communication failures.
As a basic element of organisms, motivation shapes the action pattern. There are abundant biological and social systems that originate from motivations, which have attracted widespread attention. To pave the technical foundation of relevant researches, this paper presents an effective model to simulate the spatial distribution of motivation within complex environments, which is named as the quasi-potential field. Our modelling process includes three steps. First, we suggest an original algorithm for structure reduction, which can preserve all the topological properties of a given environment. Second, we define the quasi-potential value on the reduced structure, which works as the root of the whole field. Third, we extend the field from the root to all the available spaces. Thus, the motivation distribution in the real environment can be finally generated. In our paper, several simulation experiments are carried out to verify the effectiveness of our model, whose results are proved to be promising.
Forests have crucial importance for the sustainability of Earth and humanity and one of the biggest threats to the existence of forests are the fires. This paper proposes a conceptual model for mitigating forest fire risk by use of self-adaptive and autonomous unmanned aerial vehicles (UAVs). Memoryless property of exponential distribution is also reflected and considered in the calculations of forest fire probabilities. Stochastic and dynamic properties of the situation and the mathematical complexity of the routing problem entailed and justified a simulation study. The effectiveness of the proposed dispatching approach for routing UAVs and the validity of the proposed model are tested on a small sized realistic scenario. Experimental results encourage the development of complex models. Integrating the proposed model with advanced information technologies may lead to the development of a digital twin system.
This paper describes DyFMCapA, a tool for analyzing a defense force's capacity to meet time-varying mission demands, and illustrates the exploration of metrics with which to inform the modification of a force's mix of assets. The importance of key requirements for agility in modeling and analysis is highlighted: a common modeling, simulation, data analysis, and visualization environment that supports a combination of relational data operations with array and imperative computation, and having mature programmatic and data interfaces to the prevailing data source environment.
In this paper, we consider a multi-pair two-way full-duplex relaying system with multiple-input-multiple-output (MIMO) users. Each pair of users exchange information with the aid of a massive MIMO amplify-and-forward (AF) relay, and correlation between the antennas both at the users as well as the relay is considered. The direct link between all user nodes is assumed to be non-negligible, which is suitable for practical urban scenarios. The low-complexity transceiver design at the relay based on maximum ratio combining/maximum ratio transmission (MRC[MRT) processing is presented. The performance of the system is evaluated in terms of the achievable sum-spectral efficiency under two communication schemes. The first scheme attempts to make use of the joint benefits of the relayed and direct links, while in the second scheme the direct link is considered as interference. Comparison analysis show that the first scheme outperforms the second in the presence of a strong direct link. Moreover, the detrimental effect of spatial correlation between the antennas at each user node is investigated.
Within the scope of the personnel organization, it should be clarified, which employees are to be responsible for what kind of maintenance tasks. The individual competence of an employee's abilities can be checked against the maintenance requirements using the well-known profile comparison. However, it is less clear how the corporate competence of a team of employees can be identified, but a suitable solution can be found using the personnel-oriented simulation. Regarding the organizational structure of the staff, maintenance tasks are often transferred to a central department. However, there is also a tendency to integrate them into the production area. In many cases this results in mixed organizational forms of central and decentralized maintenance. A novel product quality-oriented maintenance concept will be presented and simulated using the example of a mechanical workshop. In addition to a case-related planning solution, general statements on the department organization of maintenance are derived.
Software systems need to be complex and large-scale to keep up with growing user expectations with ever-increasing technological improvements. Building these systems from scratch is costly and time-consuming; thus, the importance of reuse and interoperability is increasing. Live-virtual-constructive (LVC) simulation systems are composed of multiple heterogeneous subsystems. These subsystems may have different implementations and designs. In such multiarchitecture LVC environments, gateways are promising solutions to address interoperability issues. In this article, a gateway-based solution is proposed to achieve LVC interoperability with a particular focus on two standard middleware, namely, data distribution service for real-time systems (DDS) and high-level architecture (HLA) for distributed simulation. The gateway is capable of providing two-way data transfer between DDS and HLA. The design of the gateway adheres to the idea of configurable connectors, which allow users to generate a customized gateway. The gateway is capable of converting primitive and structured data types between DDS and HLA. These conversions are specified by users resulting in different configurations of the gateway. The gateway can also be adapted to different configurations at runtime. This research addresses the increasing importance of interoperability and reuse considering the complex and large-scale LVC systems. The effectiveness of the proposed gateway is demonstrated by academic and industrial case studies.
The technological revolution of the Internet of Things (IoT) is transforming our society by registering and analyzing users and infrastructures' behavior in order to develop new services for improving life quality and resource management. IoT-based applications demand a vast amount of both localized and location-based information services. For these scenarios, current cloud-based services appear to be inefficient in terms of latency, throughput and power consumption. Edge computing proposes new infrastructures for effective real-time decision making. These facilities should be able to process a vast amount of data from multiple geographically distributed sources. To that end, new urban edge data centers are to be deployed, bringing computing resources closer to data sources while reducing both core network congestion and overall energy demand. This paper presents an Edge Federation simulator for data stream analytics in a 5G scenario that provides the necessary resource management for efficient service-oriented computing.
System Entity Structure (SES) is a high-level ontology which was introduced for knowledge representation of decomposition, taxonomy and coupling of systems. It has its roots from the systems theory-based approaches to modeling and simulation. SES has been applied for various purposes by modeling and simulation community, however, there still exists a lack of standardized computational representation. This hinders the shareability of SES artifacts and interoperability of SES tools. In search for wider acceptance and eventual standardization, this paper proposes a computational representation and supporting application agnostic tool suite: SESEditor and PESEditor.
Rollbacks are widely used to maintain causality parallel optimistic simulations, specifically in Time Warp synchronized simulations. Despite their significance, literature is scant on fundamental characterization of the two key metrics of rollbacks, namely - 1 inter-rollback cycles, i.e., how many event processing cycles elapse before a rollback occurs, and 2 rollback lengths, i.e., how many cycles does a rollback cancel. This study proposes an experimental method to characterize rollbacks via statistical analysis. We have conducted experimental analyses using a widely used synthetic benchmark called phold. We have conducted 1000s of simulations with different combinations of phold settings on two different computational-clusters to analyze rollback-profiles of a broad spectrum of parallel simulation configurations. Our analysis shows that both rollback metrics are geometrically distributed with their aggregate characteristics following a normal distribution. Interestingly, the overarching metrics from 500 different simulation configurations are also normally distributed.
The Cell-DEVS methodology is formal modeling technique that permits defining each cell in a cell space as individual independent entity. We used Cell-DEVS to build a library that allows defining different models of traffic. We show how to model cell spaces with emerging behavior using this methodology. We present basic models and visualization tools based on 3D models in Maya.
As society and industry relies extensively on Cyber-Physical Systems (CPS), any malfunctions can have unforeseen catastrophic failures. Fault Injection (FI) techniques perturb a model of a CPS with the intention of causing a failure and measuring the robustness of the CPS. Naturally, the success of a FI simulation depends on three factors: (i) the realism of the faults injected; (ii) how quickly the faults cause catastrophic failure; and (iii) the fidelity of the model used. This paper proposes to improve the success rate of FI studies by addressing each one of these factors. An algorithm is presented that leverages traditional sensitivity analysis in hybrid systems to reduce an uncountable fault search space to a optimal finite set (factors and we use co-simulation as the model integration technique (factor iii). We evaluate our contribution on the power window system developed by MathWorks®.
Schruben's Event Graphs (EGs), defining the event types of a simulation model and event scheduling arrows between them, representing causal regularities, provide an elegant visual modeling language and formalism for event-based simulation, which can be viewed as the most fundamental Discrete Event Simulation (DES) approach. We show how to extend and visually improve the language of EGs by adding elements of the Business Process Modeling Notation (BPMN): (1) mini diamonds for designating conditional control flow arrows, (2) Gateways for conditional and parallel branching, (3) typed Data Objects for accommodating object-oriented (OO) state structure modeling, and (4) Activities. The resulting extension of EGs, called Discrete Event Process Modeling Notation (DPMN), is more expressive and visually more clear than traditional EGs, and its visual syntax is harmonized with BPMN process diagrams, thus building a bridge between the DES and the Business Process Management research communities.
Deep learning is a powerful means to classify and thus optimize Energy management in Buildings. Deep learning is effective especially when the training dataset has a reduced volume or when the test set changes at a higher frequency than the training set. Notwithstanding these favourable properties, the classification with deep learning could be distorted by an adversary who can be interested to alter the classification of the energy consumption. Several kinds of fraud could require this attack, as those aimed at energy theft. In this paper we will provide experimental implants where a dataset is tampered with in order to lead the classifier to acquire it as valid, while it contains samples attributable to energy thefts.
Autonomous vehicles will increasingly shape the streetscape in the future. At the beginning of the dissemination, interactions between autonomous vehicles will occur without a predefined communication interface. In this work, a simulation framework is set up that allows the investigation of the interaction of autonomous vehicles. In particular, an EGO centric vehicle simulation is converted into a vehicle simulation with multiple detailed modeled vehicles (MultiEGO) using co-simulation methods. To identify the risk in an early stage by using simulation methods, a criticality assessment of traffic situations is defined. In a case study, critical traffic situations are analyzed using a detailed vehicle model and a search method based on a generalized traffic scenario. This investigation shows how demanding it is to find all the driving malfunctions and gives an insight into the challenges of developing and releasing autonomous vehicles.
This paper presents property-based testing, an approach for testing implementations of agent-based simulations (ABS), never considered so far in this field. It is a complementary technique to unit-testing and allows to test specifications and laws of an implementation directly in code which is then checked using automated test-data generation. As case-studies, we present two different models, an agent-based SIR model and the SugarScape model, in which we will show how to apply property-based testing to explanatory and exploratory agent-based models and what its limits are.
In this article Non-Uniform Rational B-Spline (NURBS) surface is used to build mathematical models with various forms that can be used in a study for self-organized potential based shape determination. This requires that the NURBS model can be discretized into a hexagonal mesh like a graphene structure. Thereafter, the mesh is utilized for the determination based on the self-organization process.
