Design Of Simulation Model Research Articles

Design and simulation analysis of an improved wearable power knee exoskeleton

The wearable lower limb power robotic exoskeleton is a device that can improve the human walking ability. In this paper, an improved exoskeleton device for knee joint is designed, including the improvement of mechanical structure and hydraulic cylinder. In order to verify the effectiveness of the improvement of the hydraulic cylinder, we have carried out the following studies. Firstly, in terms of mechanical structure, length adjusting device is added to meet the needs of different people. At the same time, a limit device is added to the knee joint to improve the safety performance and comfort. Secondly, the dynamics of the model is carried out by Lagrange, and the exoskeleton model is established for ADAMS motion simulation. The force of ADAMS simulation, the calculated by Lagrange equation and the force of the first edition of hydraulic cylinder are compared, and the force selection of hydraulic cylinder is analyzed. By comparison with the first edition, the optimization rate of the improved hydraulic cylinder reaches 8 %. Finally, in order to verify the rationality of ADAMS simulation and the effectiveness of hydraulic cylinder improvement, the wear test is carried out, the average errors of leg centroid in normal walking, wearing exoskeleton walking and ADAMS simulation data are compared. The average error rate is less than 10 %. The results show that the simulation model design is reasonable, and the effectiveness of the hydraulic cylinder improvement is verified. The exoskeleton device designed can well follow the human motion. The simulation analysis of the exoskeleton provides important parameters for the manufacture and it also provides theoretical basis for the later control theory.

Implementation of a Single Effect Absorption LiBr-H2O Refrigeration Chiller by using Thermodynamic Modeling and Steady State Simulation

The objective of this research paper is to present steady state simulation model and EES program for design and thermodynamic analysis is used to predict the performance of single effect vapor absorption chiller. The working condition of steam is entering and exit to the generator. At that point, the program gives the thermodynamic properties of all purposes of the state, for example, design information each heat exchangers in the cycle and the overall performance of the cycle. The outcome is from EES program is utilized to contemplate the impact of structure parameters on cycle performance. In the conventional absorption refrigeration system dilute solution of LiBr is directly goes to the generator at inlet of generator in this type high heat source is required and increasing the area of the generator. In this paper is to present incorporation of heat reclaimer in the solution heat exchanger and the generator. The addition of one heat exchanger with increasing COP as well as reduced heat source and heat transfer area in the generator. This program gives the operating parameter at all state points, design value of all heat exchanger and design performance of the system. The refrigeration capacity of the system is 100TR. To check the performance of system by using changing flow rate of heat source, heat exchanger effectiveness. The output of this program and simulation results use for the sizing of new refrigeration system.

Design and Implementation of Real Time Integer Order PID Controller for Infrared Heater

A modified technique is introduced to understand the design of Integer order PID controller. Due to simple tuning rules, conventional PID controller has the great success with the automatic tuning feature and tables that simplify their design. The Integer order PID controller show better robustness performance with the comparison of PID control's experimental to Heating control system (HIL). In Integer order control, design of simulation model of system can be designed straight forwardly with design specification based on frequency analysis which can be change continuously. The simulation analysis and real time results shows that Integer order PID controller is more effective way to enhance the system control performance.

Integrated Design Approaches for 3D Printed Tissue Scaffolds: Review and Outlook.

Emerging 3D printing technologies are enabling the fabrication of complex scaffold structures for diverse medical applications. 3D printing allows controlled material placement for configuring porous tissue scaffolds with tailored properties for desired mechanical stiffness, nutrient transport, and biological growth. However, tuning tissue scaffold functionality requires navigation of a complex design space with numerous trade-offs that require multidisciplinary assessment. Integrated design approaches that encourage iteration and consideration of diverse processes including design configuration, material selection, and simulation models provide a basis for improving design performance. In this review, recent advances in design, fabrication, and assessment of 3D printed tissue scaffolds are investigated with a focus on bone tissue engineering. Bone healing and fusion are examples that demonstrate the needs of integrated design approaches in leveraging new materials and 3D printing processes for specified clinical applications. Current challenges for integrated design are outlined and emphasize directions where new research may lead to significant improvements in personalized medicine and emerging areas in healthcare.

Analytical modelling and device design optimisation of epitaxial layer‐based III–V tunnel FET

The line tunnelling and heterojunction are two important techniques to improve the performance of the tunnelling field-effect transistors (TFETs). The TFETs that utilise both of these techniques perform superior to the conventional TFETs. The recently proposed T-shaped TFET (TTFET) is one such heterojunction-based line tunnelling device that is expected to become energy efficient switch. For the first time, a physics-based analytical model for surface potential and drain current of epitaxial layer-based heterojunction line TFET has been developed. The model describes the impact of device design parameters on the electrical performance of the device. The Poisson equation is solved with precise boundary conditions to obtain the surface potential model. Kane's model is used to calculate drain current by utilising surface potential model. A good agreement between Synopsys technology computer-aided design simulation and analytical model is observed with 5.4% error in on current at V GS = V DS = 0.5 V, an average error of 5.80% in surface potential and 7.24% in transconductance. Finally, a device design guideline is presented according to the analytical expressions.

Efficient generation of non-cubic stochastic periodic bicontinuous nanoporous structures

A direct method is proposed for the generation of 3D stochastic bicontinuous microstructures on general periodic parallelepiped cells, providing flexibility in the design of atomistic nanoporous simulation models. The method combines the ideas of Cahn with a modified Fibonacci grid to ensure the generation of a stochastic structure, while strictly enforcing periodicity in a flexibly defined parallelepiped cell. To validate the method, the topology of three parallelepiped cells is evaluated: cubic, rectangular prism, with different edge lengths, and general parallelepiped, with different edge lengths and angles. Results show consistent ligament size distribution among the different microstructures. The Mean and Gaussian curvatures for all systems calculated at different relative densities agree well with their theoretical values. The scaled genus density for relative density ranging from 25% to 55% is in good agreement with experimental values and data from molecular dynamics and phase field methods. The proposed method offers an efficient framework for the generation of 3D stochastic periodic bicontinuous microstructures. The method is particularly convenient in the design of adjustable nanoporous models for atomistic simulations.

A system dynamics simulation model to evaluate project planning policies

ABSTRACT Computer simulation modeling approach has been used for the last decades to address the growing need for estimation, analysis and improvement of project performance indicators. In this research, a dynamic simulation model is developed capturing both hierarchical and dynamic complexities of projects. This paper discusses how changes in dynamics can influence the critical performance indicators of a project throughout its lifecycle. The designed simulation model is capable of assessing the robustness and suitability of the scope and change management policies. The validity of the model was tested by a real-world project in the petrochemical industry. The significant factors influencing a project’s performance are investigated in the case study. The simulation results indicate that resource allocation decisions could be optimized to improve project performance indicators. The developed decision model can be regarded as a flexible and predictive tool in the construction industry with the purpose of explaining the dynamic behavior of a project. Abbreviation SD: System Dynamics

Design and test of simulation model of the controller of electromechanical tap-changers for hv/mv transformer

At present, the simulation model of the electromechanical tap changer controller is not generally available. It is necessary in order to carry out tests of the voltage regulation system in the Main Supply Point (MSP). It is a lower voltage regulation system. The article presents simulation models of the tap changer controller working in a HV/MV station. The construction of all subsystems of the model is presented. Various methods of implementation of current compensation were also considered. The subsystems of the model and the whole have been simulated.

Design and Development of an Efficient Computer Simulation Model for Response Analysis of a Moored Semi-Submersible

This paper presents the design and development of an efficient modular ‘Computer Simulation Model (CSM)’ for response analysis of a moored semi-submersible. The computer simulation model is designed in two split models (i.e. computational and experimental models) and each of these models consists of various modules. The modules are developed from basic governing equations related to motion and modules are integrated and we aim for a seamless integration. The moored semi-submersible is represented mathematically as six degrees of freedom dynamic system and the coupling effects between the structure and mooring lines are considered. The basic geometric configuration of semisubmersible is modelled and analyzed for stability computations in MS-Excel*TM and then the basic governing equations related to motion are modelled mathematically in a module and solved numerically with Ansys-AQWA**TM. The computational model is validated and verified with some available experimental results. The CSM is utilized to study the surge and sway responses with respect to the horizontal range of mooring lines and our results show good validation with the existing experimental results. Our presented results show that the fibre wires have minimum steady state response in surge and sway degrees of freedom as compared with the steel wires. However, they have large drift as compared with steel wires. Finally, we show that the computer simulation model can help in detailed analysis of responses and results can be utilized for design and development of new age semi-submersibles for optimum performances for a given set of parameters.

Optimum Configuration of Solar PV Topologies for DC Microgrid Connected to the Longhouse Communities in Sarawak, Malaysia

In the past few years, the prime focus of supplying electricity to the longhouse communities in the rural areas of Sarawak has been initiated based on the utilization of a single-source microgrid configuration. The existing AC power supply-based solar photovoltaic (PV) systems in these areas pose many problems, mainly owing to the stages of conversion, energy losses, and the quality of power transfer. As the solar PV system is a DC source and most of the appliances in longhouse communities could be operated using DC source, an opportunity to design a microgrid with high reliability and efficiency would be achieved by the implementation of an optimal DC microgrid configuration. With this aim, the paper proposes a multiple-source DC microgrid configuration for the longhouse communities in Sarawak. Initially, a framework has been developed to design simulation models for both microgrid configurations (single and multiple sources) using MATLAB Simulink. The configuration of each system consists of a solar PV and energy storage to form a standalone microgrid. Due to the change in system configuration of DC microgrid, in the modeling approach, the standard power flow equations are modified to include solely the DC parameters. To validate the proposed configuration with the associated modeling approach in terms of the power flow reliability, system efficiency, and power-voltage curve, an experimental setup representing the Simulink model has been designed for each standalone microgrid configuration. The configurations have been assessed in the same location with different daily weather conditions. The obtained simulation and experimental results confirm that the proposed configuration of multiple sources is more reliable and efficient than the existing single-source configuration.

Analysis of critical machine reliability in manufacturing cells

Purpose: In an increasingly competitive business environment, machine reliability problem merits special attention in operations of manufacturing cells. This is mainly due to flow line nature of the cellular layout, interdependency of downstream and upstream of machines related to each other. This study investigates the effect of critical machine reliability improvement on production capacity and throughput time in manufacturing cells. Design/methodology/approach: A discrete-event simulation model was developed to investigate the effectiveness of a reliability plan focusing on the most critical production machines in improving the performance level as an alternative to increasing the reliability of all machines. Four machine criticality policies are examined in the simulation experiments.Findings: The results of this experimental study indicated that an improvement of reliability of a limited number of machines leads to an increase in overall production capacity and speed in cellular manufacturing operations. A reliability plan, that focuses on a set of critical machines, potentially offers a more economical alternative to increasing the reliability of all machines in such facility.Research limitations/implications: The results demonstrate that to achieve higher production capacity and shorter throughput times, managers should consider directing more resources to increase the reliability of critical machines, particularly, those with shorter mean time to failure and higher utilization.Originality/value: The designed simulation model is unique in representing the dynamics of a real world manufacturing cell environment by encoding operational functions such as machine failure, maintenance resource allocation, material flow, job sequencing and scheduling. A new machine availability metric is defined as well.

Building heating and cooling load under different neighbourhood forms: Assessing the effect of external convective heat transfer

Neighbourhood form imposes complex effects on the local microclimate. The overlook of neighbourhood microclimate will lead to miscalculation of building energy performance. In this paper, a neighbourhood-scale building simulation coupled between building energy simulation and CFD is proposed to assess the impact of external convective heat transfer coefficient (CHTC) to the building thermal performance. The co-simulation is run for different types of buildings inside the neighbourhood with different combinations of neighbourhood form parameters. The developed simulation scheme allows the iterations of neighbourhood design parameters and simulation model generation in CFD and EnergyPlus. Five empirical methods are used to predict CHTC, and the results of CHTC values, heating and cooling load intensity are compared in detail with the proposed CFD coupled method. The results suggest that the orientation and multiplier are crucial to the building load intensity in Chicago and the neighbourhood form can affect the thermal load of residential building up to about +27.1% and −18.6%, and +17.2% and −7.7% for office buildings. The proposed method and framework in this paper is capable of generating design guidelines for the optimal energy performance of the buildings in the neighbourhood.

Prestressed Continuous Bridge Evaluation using Structural Health Monitoring System

Dorim Goh is a prestressed concrete (PSC) continuous bridge in Seuol, Korea. The structural health monitoring is used to assess the behavior of this bridge. 12 strain, 6 displacement and two accelerometer sensors are used to collect the behavior of the bridge under static and dynamic loads. The low-pass filter is used to estimate the static behavior of bridge and extract the accurate values for the bridge performances. Six’s cases of static loads and truck’s speeds from 10 to 60 Km/h are evaluated. The maximum strain and deflection collect during static loads are 60 με and 1.8 mm, respectively. Moreover, the distribution of stress on the bridge deck is assessed, and we find that the bridge status is safe under static loads. The dynamic factor (DF) is calculated during dynamic test, and the results show that the maximum DF is 0.228. In addition, Fast Fourier Transformation (FFT) is used to estimate the dominant frequency of bridge. The dominant frequency is estimated from acceleration measurements after filtering the collection data; the results show that the dominant frequency of bridge girder is 4.94 Hz. The results are compared with the design simulation model results and we find that the bridge is safe under applied loads.

Design of zeolite boiler in thermochemical energy storage and transport system utilizing unused heat from sugar mill

In Tanegashima, an isolated island in Japan, a 1500 ton/day sugar mill produces raw sugar and residual bagasse simultaneously. The bagasse is burned to generate steam that drives power turbines, but the bagasse boiler burns more bagasse than that is required. Accordingly, the process has a high temperature flue gas and a sizeable amount of unused heat at around 200 °C is exhausted from the sugar mill. Conversely, many other factories on the island burn imported oil in package boilers to generate process steam at temperatures up to 120 °C, all year around. To resolve this spatial and seasonal mismatch, we employ a thermochemical energy storage and transport system that uses a zeolite steam adsorption and desorption cycle. We introduce a basic design of a heat discharging device (a “zeolite boiler”) that features a moving bed with an indirect heat exchanger. The zeolite boiler’s performance is predicted by an in house designed simulation model that includes empirical equilibrium adsorption kinetics and a heat transfer model of the exotherm for zeolite 13X adsorbing water vapor. The effects of the mass flow rates of zeolite and injected steam are computed and suggest that optimal conditions to produce 800 kg/h of steam could decrease fuel consumption by the existing oil-fired package boiler of 23.2%. We then design an advanced zeolite boiler to recover the zeolite’s sensible heat, which would otherwise be wasted. Employing this economizing process yielded a total decrease in fuel consumption of 29.6%.

A methodology for design and fatigue analysis of power cables for wave energy converters

The recent development of subsea power cables for various offshore marine renewable energy technologies has identified the need for new cables that have low structural stiffness properties. This type of cable is referred to as dynamic cable because of its high bending flexibility compared to static cables. The current study presents a cable design model and simulation models that were developed for the design and fatigue analysis of dynamic cables. These models were applied on a subsea dynamic power cable with a design that is suitable for a floating point-absorbing wave energy converter (WEC), where the cable must withstand cyclic loads imposed by the motions of the WEC, the waves and the ocean currents. The cable design model is presented with its detailed design and dimensioning methodology for cables with multiorder helical structures, with respect to desired (target) mechanical properties. The cable design model is verified against a verification study in the literature. A simulation model of a fatigue test rig for accelerated rotational bending is presented. The results from the numerical simulations and the subsequent fatigue analyses are compared against results from experiments using the test rig. The influence of the dynamic effects and mechanical properties on the fatigue life of the cable is discussed. This study contributes to a better understanding of the fatigue failure mechanisms of the cable, and it also highlights the importance of further development of numerical models.

Design of simulation models and study on their basis the dynamics of the cyclic mechanisms

Reliability and performance of mechanical systems of cyclic action are largely determined by the level of oscillatory processes in their links. Violation accuracy positioning of the output links mechanisms, the destruction of their elements during operation, accelerated wear - all this is the result of the presence of dynamic forces in the mechanism, the speed of the elements of which cyclically changes from a certain minimum to maximum value. Calculations of such mechanisms are based on their dynamic models. A model is a representation of a mechanism in the form of a system of concentrated masses connected by elastic-dissipative, piecewise-continuous (due to the presence of gaps), holonomic bonds. This work is devoted to automation processes for creating such models and calculating on their basis the dynamic characteristics of the mechanism.

PENERAPAN MODEL SIMULASI PENJADWALAN ANTRIAN NASABAH BANK MEGA PADANG

Along with progress in improving communication and information, more people who gather as much information as possible through various media had. But not everyone is able to manage information to good use at the appropriate time efficiently and effectively. Because it has a lot of information alone is not sufficient if it can not manage to become the best alternative using the simulation system model of scheduling customers in a bank queue. With the design of simulation models the scheduling queue is expected to provide customers get into the parties will try to develop a simulation, so it can be seen every error that occurs during the development of models and simulations. The design of this system using excel simulation tests, with the implementation of systems using Microsoft Access 2003 database system and program visual basic 6.0. From system design are made to dipe.

Integrating Simulation-Based Optimization for Lean Logistics: A Case Study

The present work aims at the comprehensive application of stochastic and optimization tools with the support of Information and Communication Technologies (ICT) through a case study in a logistics process for electronic goods; simulation and Response Surface Methodology (RSM) are applied for this purpose. The problem to be evaluated is to define an optimal distribution cost for products shipped to wholesale customers located in different cities in Mexico from a manufacturing plant in Tijuana, Mexico. The factors under study are the product allocation for each distribution center, finished good inventory level and on time deliveries, which are supposed to be significant to get the objective. The methodology applied for this problem considers the design of a discrete event simulation model to represent virtually the real life of logistics process, which is considered a complex system due to different activities are interrelated to carry it out. This model is used to execute the different experiments proposed by the RSM. The results obtained from simulation model were analyzed with the RSM to define the mathematical model that allows identifying the parameters of the factors in order to optimize the process. The findings prove how the ICT facilitate the application of stochastic tools with the purpose of process optimization.

Comparación multinivel de grandes sistemas urbanos

For the first time the systems of cities in seven countries or regions among the largest in the world (China, India, Brazil, Europe, the Former Soviet Union (FSU), the United States and South Africa) are made comparable through the building of spatio-temporal standardised statistical databases. We first explain the concept of a generic evolutionary urban unit (“city”) and its necessary adaptations to the information provided by each national statistical system. Second, the hierarchical structure and the urban growth process are compared at macro-scale for the seven countries with reference to Zipf’s and Gibrat’s model: in agreement with an evolutionary theory of urban systems, large similarities shape the hierarchical structure and growth processes in BRICS countries as well as in Europe and United States, despite their positions at different stages in the urban transition that explain some structural peculiarities. Third, the individual trajectories of some 10,000 cities are mapped at micro-scale following a cluster analysis of their evolution over the last fifty years. A few common principles extracted from the evolutionary theory of urban systems can explain the diversity of these trajectories, including a specific pattern in their geographical repartition in the Chinese case. We conclude that the observations at macro-level when summarized as stylised facts can help in designing simulation models of urban systems whereas the urban trajectories identified at micro-level are consistent enough for constituting the basis of plausible future population projections. Keywords: urban system, Zipf's law, Gibrat, cities trajectories, BRICS

Design of Graphical User Interface Development Environment Software for sizing of Grid Connected Photovoltaic (GCPV) system

This work presents a design of graphical user interface development environment (GUIDE) software for sizing of Grid Connected Photovoltaic (GCPV) system. The simulation model of the GCPV system design is developed by using GUIDE in MATLAB. The developed GUI display the performance of the PV system based on the three scenarios. The three scenarios are sizing based on architecture constraint, the energy required and budget constraint. The size of the GCPV system is from 4.6 kW to 60.0 kW. A GUIDE is developed to design and calculate the suitable size of photovoltaic (PV) module, analyses the optimum array configuration, selection of inverter, size of cable, determine the specific yield and performance ratio. The GUI be able to make a user’s job easier and beneficial in assisting the GCPV system design process compared to the manual calculation of the GCPV system.