StochSD: A Full Potential CSS Language for Dynamic and Stochastic Modelling, Simulation and Statistical Analysis

It is vital that a well-defined conceptual model can be realized by a macro-model (e.g., a Continuous System Simulation (CSS) model) or a micro-model (e.g., an Agent-Based model or Discrete Event Simulation model) and still produce mutually consistent results. The Full Potential CSS concept provides the rules so that the results from macro-modelling become fully consistent with those from micro-modelling. This paper focuses on the simulation language StochSD (Stochastic System Dynamics), which is an extension of classical Continuous System Simulation that implements the Full Potential CSS concept. Thus, in addition to modelling and simulating continuous flows between compartments represented by “real” numbers, it can also handle transitions of discrete entities by integer numbers, enabling combined models to be constructed in a straight-forward way. However, transition events of discrete entities (e.g., arrivals, accidents, deaths) usually happen irregularly over time, so stochasticity often plays a crucial role in their modelling. Therefore, StochSD contains powerful random functions to model uncertainties of different kinds, together with devices to collect statistics during a simulation or from multiple replications of the same stochastic model. Also, tools for sensitivity analysis, optimisation and statistical analysis are included. In particular, StochSD includes features for stochastic modelling, post-analysis of multiple simulations, and presentation of the results in statistical form. In addition to making StochSD a Full Potential CSS language, a second purpose is to provide an open-source package intended for small and middle-sized models in education, self-studies and research. To make StochSD and its philosophy easy to comprehend and use, it is based on the System Dynamics approach, where a system is described in terms of stocks and flows. StochSD is available for Windows, macOS and Linux. On the StochSD homepage, there is extensive material for a course in Modelling and Simulation in form of PowerPoint lectures and laboratory exercises.

THE METHOD OF PHOTOPLASTIC SIMULATION AND ITS APPLICATION ON COMPLICATED DEFORMATION

The paper concisely introduced the hoopment of photoplastic simulation and the principle of its appli- cation.Deformations of combine extrusion and strain distributin in the process of upsetting the cylinder with void were studied by this physical photoplasic simulation method. Some important informations obtained from the simulation experiment are helpful to understand the deformation law and the charac- teristics of material flowing.The validity of the physical simulation method and the importance of com- bining the physical simulation method with numerical simulation method together were proposed in the paper.

Novel Cylinder Movement Modeling Method Based on Aerodynamics

The cylinder movement is affected by multiple factors and it is difficult to establish the accurate movement model of the cylinder. In order to improve the reliability of the production line design and to speed up the production line debugging, a novel cylinder movement modeling method based on aerodynamics is proposed. The kinetic theory, thermodynamic theory and kinematics knowledge are applied and integrated various factors which affect the movement characteristics of the cylinder are considered. According to the proposed mathematical model of cylinder movement, thecombined simulation software of cylinder movement based on Visual Studio and Visual Component （3D Create） is developed to calculate thevelocity, accel- eration and movement time of the cylinders during the running of the assembly line. Comparison results of cylinder＇s movement time under different intake air and displacement show that the mathematical model of cylinder movement based on aerodynamic is more accurate and the degree of fittingis 0.9846, which proves the effectiveness of the combined simulation software of cylinder movement. By the cylinder movement modeling method based on aerodynamic, accurate value of takt and the debug parameters can be calculated as a reference for the designers and debuggers of the cylinder-driven assembly lines.

Parallel Critical Path Tracing——A Fault Simulation Algorithm for Combinational Circuits

Critical path tracing,a fault simulation method for gate-level combinational circuits,is extended to theparallel critical path tracing for functional block-level combinational circuits.If the word length of the hostcomputer is m,then the parallel critical path tracing will be approximately m times faster than the originalone.

Chance-constrained Coordinated Optimization for Urban Electricity and Heat Networks

Urban electricity and heat networks(UEHN)consist of the coupling and interactions between electric power systems and district heating systems,in which the geographical and functional features of integrated energy systems are demonstrated.UEHN have been expected to provide an effective way to accommodate the intermittent and unpredictable renewable energy sources,in which the application of stochastic optimization approaches to UEHN analysis is highly desired.In this paper,we propose a chance-constrained coordinated optimization approach for UEHN considering the uncertainties in electricity loads,heat loads,and photovoltaic outputs,as well as the correlations between these uncertain sources.A solution strategy,which combines the Latin Hypercube Sampling Monte Carlo Simulation(LHSMCS)approach and a heuristic algorithm,is specifically designed to deal with the proposed chance-constrained coordinated optimization.Finally,test results on an UEHN comprised of a modified IEEE 33-bus system and a 32-node district heating system at Barry Island have verified the feasibility and effectiveness of the proposed framework.