In view of increasing application of sensitivity assessment (SA) to environmental simulation models, a relatively short, informal introduction to aims and methods of SA is given. Their variety, ...motivation and scope are illustrated by outlines of a broad selection of approaches. Methods based on derivatives, algebraic analysis, sparse sampling, variance decomposition, Fourier analysis and binary classification are included.
•A concise introductory overview of sensitivity assessment (SA) methods for simulation models is given.•A broad selection of methods is introduced informally and with no more mathematics than necessary.•The motivation of the methods, their scope and their limitations are discussed.•Derivative-based SA, algebraic SA, SA of dynamical models, sampled SA, regional SA and SA by emulation are outlined.
Risks are involved in every aspect of earthwork projects. This paper specifically discusses the cost risk associated with the volume calculation of such projects. In the design phase, it is not ...possible to accurately predict the quantity per soil type underground of the site. As a result, there are uncertainties in the excavation cost that may cause cost overrun. There is a need for an innovative method to forecast, control, monitor, and manage excavation cost from design phase to completion. There is, however, an innovative method for calculating volume accurately using a digital surface model method. The digital surface model can be acquired using GPS and unmanned aerial vehicles (UAV). This paper proposes a simulation model which is able to analyze, control, and monitor the cost based on excavation volume so stakeholders are able to gain the actual volume quickly and accurately. Monte Carlo simulation is applied to the excavation volume per soil type, resulting in a range of possible outcomes for excavation cost. The developed model was verified by applying it to an actual case project. Throughout the project, the cost was successfully monitored and maintained below the maximum expected cost. However, the final actual cost in the last simulation almost reached the maximum expected cost, indicating the need for cost monitoring. By periodically comparing the simulation result to the actual excavated volume obtained from the UAV, the proposed model can assist stakeholders in controlling the cost overrun risk and developing strategies during the earthwork life cycle.
In this paper, the performance of several sliding mode control strategies used for the boost driver in LED headlamps is analysed and compared. At first the topology, control framework, and ...mathematical model of the boost LED driver is presented. Based on the mathematical model, a traditional differential sliding mode control law, a terminal sliding mode control law with finite convergence time, and a 2nd-order sliding mode control law with the Super-Twisting algorithm are derived and designed. Finally the simulation models of these sliding mode control laws are built. Simulation results show that the terminal sliding mode control has a faster convergence speed than the traditional differential sliding mode control. And the 2nd-order sliding mode control has a fastest convergence speed and low chattering, but the control result has a certain overshoot.
Advances in sports medicine, rehabilitation applications and diagnostics of neuromuscular disorders are based on the analysis of skeletal muscle contractions. Recently, medical imaging techniques ...have transformed the study of muscle contractions, by allowing identification of individual motor units' activity, within the whole studied muscle. However, appropriate image-based simulation models, which would assist the continued development of these new imaging methods are missing. This is mainly due to a lack of models that describe the complex interaction between tissues within a muscle and its surroundings, e.g., muscle fibres, fascia, vasculature, bone, skin, and subcutaneous fat. Herein, we propose a new approach to overcome this limitation. In this work, we propose to use deep learning to model the authentic intra-muscular skeletal muscle contraction pattern using domain-to-domain translation between in silico (simulated) and in vivo (experimental) image sequences of skeletal muscle contraction dynamics. For this purpose, the 3D cycle generative adversarial network (cycleGAN) models were evaluated on several hyperparameter settings and modifications. The results show that there were large differences between the spatial features of in silico and in vivo data, and that a model could be trained to generate authentic spatio-temporal features similar to those obtained from in vivo experimental data. In addition, we used difference maps between input and output of the trained model generator to study the translated characteristics of in vivo data. This work provides a model to generate authentic intra-muscular skeletal muscle contraction dynamics that could be used to gain further and much needed physiological and pathological insights and assess and overcome limitations within the newly developed research field of neuromuscular imaging.
This paper investigates the performance of the credit‐card‐augmented Divisia monetary aggregates in forecasting US inflation and output growth at the 12‐month horizon. We compute recursive and ...rolling out‐of‐sample forecasts using an autoregressive distributed lag model based on Divisia monetary aggregates. We use the three available versions of those monetary aggregate indices, including the original Divisia aggregates, the credit card‐augmented Divisia, and the credit‐card‐augmented Divisia inside money aggregates. The source of each is the Center for Financial Stability. We find that the smallest root mean square forecast errors are attained with the credit‐card‐augmented Divisia indices used as the forecast indicators. We also consider Bayesian vector autoregression for forecasting annual inflation and output growth.
Abstract
In order to better solve the problems of current cable-overhead hybrid lines that are affected by transition resistance, fault phase angle, and fault type in fault location, this paper ...proposes to use the zero-sequence current method to determine the large fault section first, and then according to the electromagnetic time reversal theory (EMTR) to realize the accurate location of faults in small sectionsa. A simulation model of a cable-overhead hybrid transmission line was established using ATP-EMTP, and the program was verified in MATLAB. The simulation results show that the method is not only not affected by the transition resistance and the phase angle of the fault, but also the type of fault has no effect on the results of the distance measurement, and it has higher positioning accuracy. With the allowable relative error, different types of faults can be accurately located.
Abstract
Aiming at the small output displacement of the gas-liquid temperature difference power device, a flexible hinge displacement amplification system was designed and optimized using the lever ...principle. The formula for calculating the magnification of the lever-type flexible hinge mechanism was derived by taking into account the offset of the flexible hinge's rotational center. Likewise, consider how the parameters of the mechanism affect the output performance of the amplifying mechanism. Combining SolidWorks and Workbench to improve the amplifying mechanism's parameters, find the best value for the parameters, and experimentally validate the optimized results. The research shows that the error between the experimental data and the finite element simulation value is 2.49%, which verifies the correctness of the simulation model. The design goals of high magnification of the mechanism and output after displacement amplification are realized.
Using computer‐aided design (TCAD) simulation, the impact of the Fe doping profile, including concentration, decay rate, and depth of the doping region on current‐collapse magnitude (▵CC) in 0.5‐μm ...gated GaN‐based high electron mobility transistors (HEMTs) is systematically investigated. Accurate simulation models are established and developed to facilitate the fabrication of electronics. It is elucidated that the intricate interplay between trapping and de‐trapping of Fe‐related traps at the gate‐drain edge is responsible for current collapse. The concentration and decay rate of the doping region have a more significant impact on current collapse than the depth. Increased trap state density near two‐dimensional electron gas (2DEG) channel caused by deep‐level acceptors would boost ▵CC. However, a minor dynamic reduction in 2DEG density (nT) induces a relatively small ▵CC. By adjusting the concentration, decay rate, and depth of the doping region, ▵CC of GaN‐based Radio Frequency (RF) HEMTs can be reduced by approximately 50.3 %. The optimized distribution of Fe doping discussed in this work helps to prepare GaN‐based RF HEMTs with a limited current collapse effect.
Accurate simulation models are established and developed to investigate Fe doping profile on current collapse in GaN‐based Radio Frequency (RF) high electron mobility transistors (HEMTs). By controlling Fe doping profile in GaN buffer layer, current‐collapse magnitude (▵CC) of GaN‐based RF HEMTs can be reduced by approximately 50.3 %.
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