Distributed Simulation Approach Research Articles

Environmental effect of high-, upper, and lower middle-income economies’ energy mix: Is there a trade-off between unemployment and environmental quality?

The fact that scenarios of high unemployment potentially offer the opportunity for improved environmental sustainability remains a dilemma. In instances when environmental sustainability is triggered by increased unemployment, that poses a challenge in the simultaneous achievement of sustainable development goals (SDGs) 8 (decent work and economic growth) and 13 (climate action). On the basis of this concern, in this study, we examine whether a swap association exists between unemployment and environmental quality vis-à-vis the environmental Phillips curve (EPC) hypothesis for high-, upper, and lower middle-income (HUmLmI) economies (comprising both developed and developing countries) over the period 1990–2020. We used the novel dynamic autoregressive distributed lag simulation approach. From the findings, the EPC hypothesis is not valid in high-income (developed) economies in the short and long term. However, the validity of the EPC hypothesis was upheld in the upper and lower middle-income (developing) economies. This implies that the lack of decent work opportunities/high unemployment rates hampers environmental quality in high-income countries, promotes environmental quality in upper middle-income countries, and does not drive environmental quality in lower middle-income countries. In addition, economic growth and the use of fossil energy exacerbate environmental degradation. On the other hand, the consumption of renewable energy sources reduces environmental woes by −0.22, −0.54, and −1.15 in HUmLmI countries, respectively. This shows that renewable energy sources adapt to the environmental sustainability motive. These results imply that policy instruments to drive SDGs 8 and 13 in these income-categorized economies should be case specific rather than taking a unilateral policy approach.

Revisiting the nexus between fiscal decentralization and CO2 emissions in South Africa: fresh policy insights

The argument over fiscal decentralization and carbon dioxide emission (CO2) reduction has received much attention. However, evidence to back this claim is limited. Economic theory predicts that fiscal decentralization affects environmental quality, but the specifics of this relationship are still up for debate. Some scholars noted that fiscal decentralization might lead to a race to the top, whereas others contended that it would result in a race to the bottom. In light of the current debates in environmental and development economics, this study aims to provide insight into how this relationship may function in South Africa from 1960 to 2020. In contrast to the existing research, the present study uses a novel dynamic autoregressive distributed lag simulation approach to assess the positive and negative changes in fiscal decentralization, scale effect, technique effect, technological innovation, foreign direct investment, energy consumption, industrial growth, and trade openness on CO2 emissions. The following are the main findings: (i) Fiscal decentralization had a CO2 emission reduction impact in the short and long run, highlighting the presence of the race to the top approach. (ii) Economic growth (as represented by the scale effect) eroded ecological integrity. However, its square (as expressed by technique effect) aided in strengthening ecological protection, validating the environmental Kuznets curve hypothesis. (iii) CO2 emissions were driven by energy utilization, trade openness, industrial value-added, and foreign direct investment, whereas technological innovation boosted ecological integrity. Findings suggest that further fiscal decentralization should be undertaken through further devolution of power to local entities, particularly regarding environmental policy issues, to maintain South Africa’s ecological sustainability. South Africa should also establish policies to improve environmental sustainability by strengthening a lower layer of government and clarifying responsibilities at the national and local levels to fulfill the energy-saving functions of fiscal expenditures.

Testing the pollution haven hypothesis on the pathway of sustainable development: Accounting the role of nuclear energy consumption

The environmental effects of China's nuclear energy consumption in a dynamic framework of the pollution haven hypothesis are examined. This study uses a dynamic autoregressive distributed lag simulation approach. Empirical evidence confirms that the pollution haven hypothesis does not exist for China; i.e., foreign direct investment plays a promising role in influencing environmental outcomes. Furthermore, empirical results concluded positive contribution of nuclear energy in pollution mitigation. From the results it is expected that encouraging foreign investment to increase generation of nuclear energy would benefit environmental quality by reducing CO2 emissions.

Distributed simulation: state-of-the-art and potential for operational research

In Operational Research conventional simulation practices typically focus on the conceptualization, development and use of a single model simulated on a single computer by a single analyst. Since the late 1970s the field of Distributed Simulation has led research into how to speed up simulation and how to compose large-scale simulations consisting of many reusable models running using distributed computers. There have been significant advances in the theories and technologies underpinning Distributed Simulation and there have been major successes in defence, computer systems design and smart urban environments. However, from an Operational Research perspective, Distributed Simulation has had little impact on mainstream research and practice. To argue the potential benefits of Distributed Simulation for Operational Research, this article gives an overview of Distributed Simulation approaches and technologies as well as discussing the state-of-the-art of Distributed Simulation applications. It will investigate the potential advantages of Distributed Simulation for Operational Research and present a possible sustainable future, based on experiences from e-Science, that will help Operational Research meet future challenges such as those emerging from Big Data Analytics, Cyber-physical systems, Industry 4.0, Digital Twins and Smart environments.

Multi-level simulation of Internet of Things on smart territories

In this paper, a methodology is presented and employed for simulating the Internet of Things (IoT). The requirement for scalability, due to the possibly huge amount of involved sensors and devices, and the heterogeneous scenarios that might occur, impose resorting to sophisticated modeling and simulation techniques. In particular, multi-level simulation is regarded as a main framework that allows simulating large-scale IoT environments while keeping high levels of detail, when it is needed. We consider a use case based on the deployment of smart services in decentralized territories. A two level simulator is employed, which is based on a coarse agent-based, adaptive parallel and distributed simulation approach to model the general life of simulated entities. However, when needed a finer grained simulator (based on OMNeT++) is triggered on a restricted portion of the simulated area, which allows considering all issues concerned with wireless communications. Based on this use case, it is confirmed that the ad-hoc wireless networking technologies do represent a principle tool to deploy smart services over decentralized countrysides. Moreover, the performance evaluation confirms the viability of utilizing multi-level simulation for simulating large scale IoT environments.

Implementation of Health Monitoring System using Mixed Environment

Background: Research shows that the health care cost per capita have grown 2.4 percent faster than the gross domestic product (GDP) since 1970. The aim of this paper is to present a useful model of wireless system that can combine both hardware and software environments and it can also integrate with other technologies or infrastructure at a low cost, which can be used for the patient monitoring system. Methods: The biomedical sensor which is attached to the patient, will read analog data. The recorded data will be converted digitally by using Analog to Digital Converter (ADC) and a FPGA transmitter will be used to send this data to Phase Shift Keying (PSK) transmitter. The modulated data will be received by PSK receiver and another FPGA receiver will be used to get the data back on the system. For behavioural modelling Verilog hardware descriptive language is used to provide a high level abstraction and language constructions. And the Simulink software is used to provide a high-level mathematical modelling condition for digital communication system which can be used for the verification and algorithm development.The important modules implemented for the transmitter and receiver FPGA are bus interfacing, compression and the data framing. Findings: A short range wireless health monitoring wireless system is modelled by using a mixed software and hardware simulation environment.At all the stages of the hardware and software designs, different types of languages like Verilog HDL codes and MATLAB used to verify the operation of the modules. The behavioural HDL designed of the FPGA transmitter and receiver will be interfaced with the RF Simulink models of PSK transmitter and receiver by using System Generator (Sysgen) tool that acts as the converter simulator. A realistic design model of health monitoring system is implemented which can be used for future hardware design. Compression and framing are the two main operations used in the transmitter side. Data compression is implemented by Run-Length Encoding method and for data framing high data link control protocol has been used. The unique features of this models simulation are low cost, less complexity, low power dissipation and efficient data transmission. Finally the FPGA based healthcare system allows us to change the design configurations or up gradation of the system based on the requirements. Conclusion: In this paper distributed simulation approach is used for designing the health monitoring system which allows checking the specification of design at all the stages. Simulation by HDL and Simulink mixed models in not the objective of this work, but to prove that realistic design is possible for future health care system design.

Ad hoc distributed simulation for transportation system monitoring and near-term prediction

The widespread deployment of sensors, computers, and communications in vehicles and roadways is creating new challenges and opportunities to effectively exploit the wealth of real-time data and information that is now becoming increasingly available. In this paper the authors capitalize on these rapid technological advancements using a technique termed on-line ad hoc distributed simulation. This approach utilizes a dynamic collection of autonomous simulations interacting with each other and with real-time data in a continuously running, distributed, real-time simulation environment. Within the ad hoc distributed simulation approach a rollback-based time synchronization method is used to allow the simulations to adapt to unanticipated changes in traffic and to changes in predictions produced by other simulations. The proposed approach is tested on a transportation network with different geographical distributions of client locations and randomized network partitioning under different traffic demand scenarios. The results demonstrate that the proposed approach has the ability to share complex traffic data among participating vehicles and process the data in an effective way to provide drivers/system monitoring with near-term traffic predictions.

Web-based Distributed Network Analyzer using a System Entity Structure over a Service-oriented Architecture

As a network’s uses, and especially the number of internet users, increases rapidly, an efficient system for managing large-network traffic datasets becomes an important issue. Although there are several network traffic analysis tools, such as tcpdump, Ethereal, and other applications, these tools have weaknesses, namely the limited size of files, the use of command line execution, the large memory and huge computational power requirements. In addition to these scalability limitations, both tcpdump and Ethereal have security issues. Files captured by these tools keep all of the packet information, such as internet protocol (IP) addresses, port numbers, and packet sizes. As well as basic network traffic information, the captured files contain secure information: user identification numbers (IDs) and passwords. Therefore, the captured files should not be allowed to be leaked out. However, network analyses need to be performed outside the target networks in some cases. This paper presents an approach to efficiently and quickly analyze a large number of network behaviors. This is achieved by applying System Entity Structure (SES) theory. To speed up evaluation time, a web-based distributed simulation approach over Service-oriented Architecture (SOA) is applied. Discrete Event System Specification/Service-oriented Architecture (DEVS/SOA) is used to deploy workloads into multi-servers, increasing overall system performance. A web-based distributed simulation contains two fundamental processes: distributing and analyzing among loosely coupled models through message-passing methods. The distributed simulation — allocating distributing models inside networks and assigning analyzing models outside networks — also allows the analysis of network behaviors out of networks while keeping important information secured.

A Novel Distributed Simulation Approach in Adaptive Distance Relaying

In this paper, an adaptive distance relaying strategy based on the global network simulation (GNS) concept is presented. The GNS concept is actually a distributed simulation approach (DSA) for piecewise analysis of large-scale power grids using diakoptics and large change sensitivity (LCS) concepts. To set each utility's relays trip settings adaptively in each power system condition, detailed short circuit analysis is run in the GNS environment. It first updates the pre-fault voltage profile across utilities and then modifies their nodal ZBus in such a way to reflect the effect of the whole network in local fault studies performed by individual utilities; hence, presenting an accurate and secure federative approach on a geographically decomposed grid using local information and computational resources. A set of currently experienced rules in distance coordination is outlined and adaptive as well as conventional relay zone settings in each sub-network are calculated based on the selected rules. An efficient easy-to-implement algorithm to consider the effect of zero sequence mutual impedance among parallel lines is also presented and well integrated into the proposed adaptive approach in the GNS environment. The IEEE 14 bus test system and a real version of a large-scale grid with more than 2,600 buses are used to illustrate the characteristics of the proposed adaptive strategy in terms of security and dependability by comparison with conventional distance protection.

A distributed time-driven simulation method for enabling real-time manufacturing shop floor control

This paper proposes a distributed simulation approach for scheduling discrete-events in manufacturing shop floors. The proposed approach employs a time-driven method to simulate occurrence of discrete-events using distributed entities that replicate physical entities in the manufacturing shop floor. In specific, the proposed approach iteratively controls the timing of discrete-events occurrence using a control theoretic model. In this approach, changing the speed of the simulation clock, termed time-scaling factor, can accelerate or decelerate the simulation speed resulting in simpler synchronizations of discrete-events and faster simulation than standard distributed discrete-event simulations according to the capability of the communication networks. Computational experiments are conducted to test the performance of the proposed system with different values of the time-scaling factor, and the relationship between the system performance and the time-scaling factor is investigated through analysis of the system model. Results obtained from the computational experiments show significant successes in speeding up discrete-event simulations in such a way that the proposed approach can be used for the control of manufacturing shop floors, providing real-time decision supports.

Conservative distributed simulation of Petri nets

This paper presents an implementation of distributed discrete event simulation of Petri nets. We consider the conservative distributed simulation approach. A method is presented: • to use any local simulator of Petri nets based to handle local simulation, • to reduce the number of Null messages used to circumvent deadlocks which can occur in the conservative approach, • to detect and resolve deadlocks.

Computer Network Integrated Manufacturing: Performance Evaluation Using Distributed Simulation

A novel approach to Computer Network Integrated Manufacturing System (CNIMS) performance evaluation is discussed. It is based on distributed discrete-event simulation. Corresponding performance and simulation models are developed to support the design of CNIMSs with a very high degree of inherent parallelism. As reference systems the systems, obtained by integration of differ-ent, may heterogeneous in application, control, management and/or computer techniques, systems in the environment of an established computer network are considered. A distribution simulation algorithm is presented which adopts the Basic distribution simulation scheme of Chandy, Misra and Bryant. It is conformed to the simulation of concurrency control and synchronization mechanisms. The proposed technology permits the assemblage of the available systems to be designed and the resultant system definition to be adjusted, taking into account such aspects as: organization and control of the processes in and among the component systems; the available equipment in the com-ponent systems (including computers and terminals); the communication lines among them (such as computer network channels and material transport channels). The performance evaluation of distributed control systems with a low degree of inherent parallelism could also yield to distributed simulation approaches, but is of less interest, because of the more close-to-centralized control there.