Design Of Simulation Experiments Research Articles

Optimizing Whole-Body Kinematics During Single-Leg Jump Landing to Reduce Peak Abduction/Adduction and Internal Rotation Knee Moments: Implications for Anterior Cruciate Ligament Injury Risk.

Knee abduction/adduction moment and knee internal rotation moment are known surrogate measures of anterior cruciate ligament (ACL) load during tasks like sidestepping and single-leg landing. Previous experimental literature has shown that a variety of kinematic strategies are associated or correlated with ACL injury risk; however, the optimal kinematic strategies needed to reduce peak knee moments and ACL injury are not well understood. To understand the complex, multifaceted kinematic factors underpinning ACL injury risk and to optimize kinematics to prevent the ACL injury, a musculoskeletal modeling and simulation experimental design was used. A 14-segment, 37-degree-of-freedom, dynamically consistent skeletal model driven by force/torque actuators was used to simulate whole-body single-leg jump landing kinematics. Using the residual reduction algorithm in OpenSim, whole-body kinematics were optimized to reduce the peak knee abduction/adduction and internal/external rotation moments simultaneously. This optimization was repeated across 30 single-leg jump landing trials from 10 participants. The general optimal kinematic strategy was to bring the knee to a more neutral alignment in the transverse plane and frontal plane (featured by reduced hip adduction angle and increased knee adduction angle). This optimized whole-body kinematic strategy significantly reduced the peak knee abduction/adduction and internal rotation moments, transferring most of the knee load to the hip.

The importance of incorporating rain intensity profiles in rainfall simulation studies of infiltration, runoff production, soil erosion, and related landsurface processes

The temporal sequence of fluctuating rainfall intensities during an event - the intensity profile or 'rainfall pattern' - is known to affect water partitioning at the ground surface and associated erosional processes. There can be large differences in runoff ratios and runoff rates between early-peak and late-peak events, and hence in the depth, speed, and sediment transport capacity of resulting overland flow. Whilst rainfall intensity may fluctuate continually during all IPs in natural rainfall, there is little information on the rates of such intensity fluctuations that can be used to guide the design of rainfall simulation experiments. This review analyses relevant data derived from published high-resolution rainfall records and also from new analyses of data from Australian ground observing stations. Both sources confirm the occurrence of rates of intensity change of greater than 500 mm h−1 min−1. It is suggested that the fluctuating intensities characteristic of natural rainfall need to be employed in rainfall simulation experiments in order to generate results applicable to natural landsurface processes like infiltration or soil removal. Constant-intensity rain, as commonly used in rainfall simulation experiments, lacks both the kinds of rapid intensity fluctuations seen in natural rainfall, as well as any representation of natural intensity profiles. These unrepresentative conditions can result in lower runoff rates and larger proportions of infiltration than when intensity fluctuations are present. There is thus a strong case for changing the design of rainfall simulation to reflect more closely natural intensity fluctuations and intensity profiles and their influence on key surface processes such as overland flow and soil erosion.

Resilience analysis for reconfigurable network with cascading failures

A network is a topology composed of nodes and the edges of connecting nodes. The nodes interact with each other through edges and realize the function of network. The break of one or several nodes in the network will cause the failure of other nodes through the connection relationship between nodes and this phenomenon is known as cascading failure. The function of large network depends on network structure. When some nodes or edges fail, the network can restore and maintain certain functions by means of reconstruction and load distribution. Based on the cluster of unmanned aerial vehicle (UAV) and communication network, the cascading failure and reconfigurable features are considered in this study. By introducing the limitation of the maximum number of connections of nodes, a multi-state cascading failure rule based on information load distribution and a dynamic network reconnection rule based on probability are proposed, and the influence of the spread and propagation of cascading failure behavior on the invulnerability of the network are studied. Through simulation experiment design and analysis, several feasible suggestions to improve the invulnerability of UAV clusters are concluded.

Rainfall drop arrival rate at the ground: A potentially informative parameter in the experimental study of infiltration, soil erosion, and related land surface processes

Rainfall drop arrival rate (DAR) quantifies the number of impacts at the ground of drops of varying size per unit area and time. It can be calculated from the drop size distribution and fall speed data used for rain integral parameters such as total kinetic energy or rainfall intensity. However, the DAR can also be calculated for individual drop size classes, revealing the relative number of impacts of small and large drops. New calculations of DAR are developed, and show that for increasingly intense rain, impacts by drops of large diameters become more common, and contribute an increasing proportion of the total kinetic energy. This may exert an important influence on many landsurface processes. A comparison with the kinds of rainfall arrival rates present in simulated rainfall is made, and suggests that although simulated rainfall may be generated with an intensity corresponding to natural rain, the DAR, especially for small and large drops, is often significantly different to the value expected in natural rain. For research on soil splash, interrill erosion, infiltration, and other important land surface processes, it is suggested that attention to DAR may prove informative, both as a potentially useful explanatory variable in field studies made under natural rainfall, and as a target parameter in the design of rainfall simulation experiments.

A tripartite game model of trust cooperation in cloud service

Cloud computing is a very popular information technology, to obtain mutual trust and win-win cooperation between the users and the cloud service provider (CSP), we propose a game model-based trust prediction. Different participants have different motives and interests in the service game process. First, we use the Bayesian formula to predict the trust level of behavior attribute, further propose trust decision function and weight algorithm of trust attribute to ensure the accuracy by maximum dispersion principle. Second, we discuss the existence possibility of the game equilibrium and establishes a dynamic game model from the short-term benefit of the user. Third, from the long-term benefit of the CSP, we establish a tripartite game model that has multiple possible equilibria that can be converted into a mixed strategy under specific common conditions. Finally, we design simulation experiments to verify the regulation and several related factors have an important influence to improve trust and honesty and control the malicious behavior of participants; further, we compare and discuss the research results with other papers in the real data set scenario, and show the advantages and highlight value.

Innovative Talents Training of Internet of Things Based on Virtual Simulation Experiment Teaching

The construction of virtual simulation teaching experiment platform environment is of great significance for colleges and universities to carry out virtual simulation experiment teaching. This paper expounds the necessity of innovative talents of Internet of things, and explains the role of virtual simulation experiment teaching platform in the cultivation of innovative talents. The virtual simulation technology is introduced into the practical teaching of the Internet of things, and the teaching practice of the virtual simulation experiment of the Internet of things is carried out, which provides a reference for the design and implementation of the virtual simulation experiment of other majors in the school of information engineering of Tarim University.

Interaction Law between Natural Fractures-Vugs and Acid-Etched Fracture during Steering Acid Fracturing in Carbonate Reservoirs

Steering acid fracturing is a technique that improves the conductivity of carbonate reservoir. It is widely used in a carbonate reservoir. However, due to the lack of comparative experiments, the application of steering acid to improve the fracturing results is still unknown. Therefore, a series of true triaxial acid fracturing experiments were conducted to study steering acid fracturing in carbonate reservoir. The carbonate specimens used in the experiment were from the Qixia group and Dengsi Member in Sichuan, China. In this study, slick water, cross-linked gel, and self-generating acid were used as ahead fluid to cooperate with steering acid. Experimental results show that (1) the low-viscosity ahead fluid with steering acid can result in more complex fractures; (2) the complexity of fractures is influenced by natural fracture and the viscosity of the ahead fluid; and (3) based on the 3D scanning results of the fracture surface, different ahead fluids will lead to different corrosion results. This study provides useful suggestions on steering acid fracturing design and physical simulation experiments.

Stochastic modelling and simulation of a kidney transplant waiting list

We created a dynamic stochastic model to evaluate the performance of a kidney transplantation system. Our model is applicable in the context of a small country where the legislation requires that a kidney from a deceased donor should be used whenever available. Using a systematic design of simulation experiments, we performed a complex simulation study based on real medical data to explore the impact of factors representing different rates of deceased kidneys harvesting, the proportion of patients with a willing living donor and different allocation policies. On the basis of careful statistical analysis carried out by two different statistical methodologies, ANOVA and bootstrap, we draw some important conclusions about the effects of these factors and recommendations for the medical community. The results of the study clearly demonstrate that in addition to increasing the numbers of kidney donors, deceased as well as living, the introduction of a kidney exchange program leads to further expansion of the numbers of donations and to shortening of waiting time for transplantation. Moreover, we observed that the largest and most counter-intuitive effect on waiting time and transplantation probability was obtained by replacing the currently implemented first-come-first-transplanted allocation policy to a policy that prioritizes the most vulnerable group of patients. This change has led to shortening the waiting time of these patients by enormous 28 months on average while leaving the waiting time of other patients practically the same.

Automatic deployment system of computer program application based on cloud computing

Cloud computing hides the huge possibility of development. It has developed rapidly in recent years. With the development of domestic cloud computing technology, cloud computing technology has become a technology of widespread concern. This research mainly discusses the design of an automated deployment system for computer program applications based on cloud computing. In order to meet the potential load conditions, computer servers usually reserve enough resources for the maximum load, which will greatly reduce resource utilization. At the same time, the server load will be monitored in real time. According to a specific capacity expansion strategy, the capacity expansion operation will be triggered in time to increase or decrease the number of back-end virtual servers to ensure the service quality of the application and increase the resource utilization rate of the server. The allocation strategy of the deployment system adopts a configurable and customizable method, which greatly improves the flexibility of the system. With the goal of expanding component-based computer program applications, format the deployment problem of component-based computer program applications, optimize deployment efficiency based on dynamic scaling algorithms, and design simulation experiments to verify the feasibility of the algorithm. Compared with previous data centers, the success rate of cloud data centers has exceeded 87%. The research results show that the deployment system can meet the specific application requirements of users, and can be properly installed and deployed in some existing systems, and can obtain better scalability according to the particularity of the cloud computing environment.

An Analytic Framework for Effective Public Health Program Design Using Correctional Facilities

We present a decision analytic framework that uses a mathematical model of Chlamydia trachomatis transmission dynamics in two interacting populations using ordinary differential equations. A public health survey informs model parametrization, and analytical findings guide the computational design of the decision-making process. The potential impact of jail-based screen-treat (S-T) programs on community health outcomes is presented. Numerical experiments are conducted for a case study population to quantify the effect and evaluate the cost-effectiveness of considered interventions. Numerical experiments show the effectiveness of increased jail S-T rates on community cases when resources for a community S-T program stays constant. Although this effect decreases when higher S-T rates are in place, jail-based S-T programs are cost-effective relative to community-based programs.Summary of Contribution: Public health programs have been developed to control community-wide infectious diseases and to reduce prevalence of sexually transmitted diseases (STD). These programs can consist of screening and treatment of diseases and behavioral interventions. Public correctional facilities play an important role in operational execution of these public health programs. However, because of lack of capacity and resources, public health programs using correctional facilities are questioned by policy-makers in terms of their costs and benefits. In this article, we present an analytical framework using a computational epidemiology model for supporting public health policy making. The system represents the dynamics of Chlamydia trachomatis transmission in two interacting populations, with an ordinary differential equations-based simulation model. The theoretical epidemic control conditions are derived and numerically tested, which guide the design of simulation experiments. Then cost-effectiveness of the potential policies is analyzed. We also present an extensive sensitivity analyses on model parameters. This study contributes to the computational epidemiology literature by presenting an analytical framework to guide effective simulation experimentation for policy decision making. The presented methodology can be applied to other complex policy and public health problems.

The Study of the Single Event Effect in AlGaN/GaN HEMT Based on a Cascode Structure

An attractive candidate for space and aeronautic applications is the high-power and miniaturizing electric propulsion technology device, the gallium nitride high electron mobility transistor (GaN HEMT), which is representative of wide bandgap power electronic devices. The cascode AlGaN/GaN HEMT is a common structure typically composed of a high-voltage depletion-mode AlGaN/GaN HEMT and low-voltage enhancement-mode silicon (Si) MOSFET connected by a cascode structure to realize its enhancement mode. It is well known that low-voltage Si MOSFET is insensitive to single event burnout (SEB). Therefore, this paper mainly focuses on the single event effects of the cascode AlGaN/GaN HEMT using technical computer-aided design (TCAD) simulation and heavy-ion experiments. The influences of heavy-ion energy, track length, and track position on the single event effects for the depletion-mode AlGaN/GaN HEMT were studied using TCAD simulation. The results showed that a leakage channel between the gate electrode and drain electrode in depletion-mode AlGaN/GaN HEMT was formed after heavy-ion striking. The enhancement of the ionization mechanism at the edge of the gate might be an important factor for the leakage channel. To further study the SEB effect in AlGaN/GaN HEMT, the heavy-ion test of a cascode AlGaN/GaN HEMT was carried out. SEB was observed in the heavy-ion irradiation experiment and the leakage channel was found between the gate and drain region in the depletion-mode AlGaN/GaN HEMT. The heavy-ion irradiation experimental results proved reasonable for the SEB simulation for AlGaN/GaN HEMT with a cascode structure.

Influence of Two Mass Variables on Inertia Cone Crusher Performance and Optimization of Dynamic Balance

Inertia cone crushers are widely used in complex ore mineral processing. The two mass variables (fixed cone mass and moving cone mass) affect the dynamic performance of the inertia cone crusher. Particularly the operative crushing force of the moving cone and the amplitude of the fixed cone are affected, and thus the energy consumption of the crusher. In this paper, the process of crushing steel slag is taken as a specific research object, to analyze the influence of two mass variables on the inertia cone crusher performance. A real-time dynamic model based on the multi-body dynamic (MBD) and the discrete element method (DEM) is established. Furthermore, the influence of the fixed cone mass and moving cone mass on the operative crushing force, amplitude and average power draw are explored by the design of simulation experiments. The predictive regression models of inertia cone crusher performance are obtained using response surface methodology (RSM). After increasing the fixed cone mass, the optimized amplitude, average power and moving cone mass are decreased by 37.1%, 33.1% and 10%, respectively, compared to without the adjustment. Finally, a more effective dynamic balancing mechanism of inertia cone crusher is achieved, which can utilize the kinetic energy of a balancer, and minimize the mass of the fixed and moving cone. The fixed cone mass and moving cone mass of a balancing crusher are decreased by 78.9% and 22.8%, respectively, compared to without the balancing mechanism.

Validation of production system throughput potential and simulation experiment design

<p>The throughput potential of a production system must be designed and validated before implementation. Design includes creating product flow by setting the takt time consistent with meeting customer demand per time period and the average cycle time at each workstation being less than the takt time. Creating product flow implies that the average waiting time preceding each workstation is no greater than the takt time. Kingman’s equation for the average waiting time can be solved for the variation component given the utilization, and the cycle time. The variation component consists of the variation in the demand and the variation in cycle time. Given the variation in demand, the maximum allowable variation in cycle time to create flow can be determined. Throughput potential validation is often performed using discrete event simulation modeling and experimentation. If the variation in cycle time at every workstation is small enough to create flow, then a deterministic simulation experiment can be used. An industrial example concerning a tier-1 automotive supplier with two possible production systems designs and various levels of variation in demand assumed is used to demonstrate the effectiveness of throughput validation using deterministic discrete event simulation modeling and experimentation.</p>

A joint production and carbon trading policy for unreliable manufacturing systems under cap-and-trade regulation

Manufacturing systems are one of the largest emitters of carbon emissions. Governments enforce environmental regulations to control and reduce such emissions. Cap-and-trade is one of the most efficient and widely-used regulations in which a tradable initial allowance is given to each emitter to sell or buy in the carbon market. In this study, we address the trading and production planning problem for unreliable manufacturing systems under cap-and-trade regulation. Regarding the carbon price which randomly changes in the market, it is challenging and complex for companies to know how to determine their production rate and trading quantity to take advantage of the carbon market. We aim to develop a new joint production and trading control policy for unreliable manufacturing systems considering the stochastic and dynamic context. Our objective is to guide the managers to jointly determine when to buy/sell allowances or increase/decrease the production rate to minimize the total cost and reduce carbon emissions of the system. The policy is specifically designed for the cap-and-trade regulation to minimize total costs consisting of emission, backlog, inventory, trading, and transaction costs. Simulation modelling, experimental design, and response surface methodology are implemented to optimize parameters of our proposed control policy. Finally, sensitivity analysis as well as comparative study are carried out to show how our proposed joint policy brings significant cost saving and emissions reduction in comparison with existing policies adapted from the literature.

Effect of particle contact point treatment on the CFD simulation of the heat transfer in packed beds

In recent years, computational fluid dynamic (CFD) simulation of fully resolved fixed beds has become a popular tool for getting deeper insight in local phenomena in packed beds. To get correct simulation results, special care has to be taken on how to treat particle/particle and particle/wall contact points.In this work a local contact point modification, the local bridges method is investigated to study its effect on the heat transfer in packed beds. Packings were created using the Discrete Element Method (DEM) software discrete Flow, and were modified to implement the bridges. Using Design of Simulation Experiments (DoSE) the influence of different parameters on the heat transfer was studied. The simulated heat transfer in packed beds, considering conduction as well as natural convection, is compared to measurements and well-established correlations. Based on the Design of Simulation Experiments, a model for the correction of the effective thermal conductivity of bridges, to reduce the simulation error as a function of particle diameter D, is suggested. The suggested correction was tested on spheres of different material and sizes to check its validity. Using this correction, the simulation error for the beds surface temperature could be reduced by 75 % in a representative example case.

Model laboratories: A quick-start guide for design of simulation experiments for dynamic systems models

The use of dynamic systems models by scientists, managers, and policy-makers is becoming more common due to the increasingly complex nature of ecological and socio-economic problems. Unfortunately, most scientific training in the life sciences only includes dynamic modeling as elective, supplementary courses at a beginners-level, which is not conducive to generating the expertise needed to properly develop, test, and learn from dynamic modeling approaches and risks utilization of poor quality models and adoption of unreliable recommendations. The objective of this paper is to fill part of that gap, particularly regarding model experimentation, by summarizing key concepts in experimental design for simulation experiments and illustrating hands-on examples of experiments needed for developing a deeper understanding of complex, dynamic systems. The experiments include extreme conditions testing, sensitivity analyses of model behaviors given variation in both parameter values and graphical (table) functions, and “what-if?” experiments (e.g., counterfactual trajectories, boundary-adequacy tests, and intervention threshold experiments). Each experimental example describes the theoretical foundation of the test, illustrates its application using an ecological systems model, and increases in degree of difficulty from novice to advanced skill levels. By doing so, we demonstrate consistent, scientific means to glean valuable insights about the model's structure-behavior link, uncover any unforeseen model flaws or incorrect formulations, and enhance the confidence (validity) of the model for its intended use.

Basic methodology in construction of vertical gardening of a building

The research covers basic procedure of the formation of a model of vertical gardening of buildings within the concept of landscape gardening, ecology of vertical gardening, green construction technologies and measures to improve the energy performance of buildings. The “objective tree” is set; it determines the current trends of development of green panes. The content of the landscape-ecological “green constructor” of plant selection is set, in order to ensure the comfort of the living environment, the formation of the biodiversity of the urbanized environment, and the resolution of the socio-ecological problems of the city and agricultural issues. For the first time, a selection procedure for vertical gardening is offered. Architectural and landscape solutions for improving the environment with green panes in the city of Volgograd are presented. The work uses multivariate landscape-ecological analysis; simulation method and experimental design of a green pane in in the city of Volgograd. The developed methodology of landscape-ecological construction of green panes allows using these ideas in domestic and foreign construction in similar environmental conditions. New landscape solutions are presented. They increase the potential of energy-saving technologies of buildings in the formation of vertical gardening, including issues of improving comfort, health and safety of people.

Optimal control and simulation for production planning of network failure-prone manufacturing systems with perishable goods

The problem of controlling the production rates of failure prone manufacturing systems has stochastic features that make it more complex and challenging. In this study, we consider a network of manufacturing machines based on the hedging point policy where the final goods are perishable, and the demand rate is constant. Our objective in this paper is to control the production rates of multiple machines in failure prone manufacturing systems in the presence of perishable goods in order to minimise the expected cost consisting of holding, shortage, perished goods and repair costs over an infinite horizon. We develop a new framework by way of a simulation-optimisation approach to deal with complexity and uncertainty. To this end, we first formulate the analytical model subject to stochastic failures and corrective repairs. Then, we use a combination of simulated annealing metaheuristic, simulation and Taguchi experimental design to estimate the optimal control policy. In addition, a numerical example is presented to illustrate the applicability and efficacy of the proposed framework.

Pedestrian gaits observed from actual pedestrian-vehicle collisions

The problem of injury protection for pedestrian is a research hot spot in traffic safety, and simulations are important research tools. In the process of design of simulation experiments, pedestrian gaits become more and more important. Hence in the research three pedestrian gait serials (walking, running and emergency) were found through observing and reconstructing 150 vehicle-pedestrian collision videos. Further studies had found that pedestrian speed and pedestrian injury are different among the three gait serials and there is significant difference between the Pedestrian Speed Before the Collision (PSBC) and the Pedestrian Speed at the Instant of the Collision (PSIC) in the same gait serial; for the emergency gait serial, there is significant difference between the estimated and reconstructed pedestrian heights; and there is high relevance between angles of the left extremities and the corresponding right extremities. Furthermore, based on results observed from the 150 videos and those existing research results, ten pedestrian gaits in each gait serial were proposed, simulation results shown that the pedestrian injury in different gait serial and in different gaits in the same gait serial are all different. The observed pedestrian gaits will help us to design a more objective simulation experiments in the future in analyzing pedestrian injury.

Research on resource allocation of vocal music teaching system based on mobile edge computing

How to allocate vocal teaching system resources plays an important role in improving the performance of vocal teaching systems. With the development of mobile edge computing, the calculation and storage of resource data can be adapted to the operating needs of vocal teaching systems. This study proposes a method of system resource allocation based on power iteration and sets the throughput of the unloading process as an objective function and realizes the optimal allocation of normal power by iterative optimization. At the same time, in view of the low energy efficiency and resource utilization of edge servers, a heterogeneous network based on edge servers is proposed to find the optimal strategy based on ensuring the Nash equilibrium point. In addition, in order to verify the performance of the algorithm in this paper, a comparative experiment is performed by designing simulation experiments. The results show that the method proposed in this paper has certain effects and strong practicability, which can provide theoretical references for subsequent related research.