سبد خرید

Pocket Book for Simulation Debriefng in Healthcare

Debriefng is a crucial aspect of simulation-based educational interventions in healthcare. This section of this pocket book aims to clarify what debriefng is really about and why it is such an important aspect of the learning process for everyone involved: participants, simulation observers, and facilitators alike. It also places emphasis on the aspect of briefng as a phase that sets foundation for a successful debriefng so learners understand the approach adopted and what will be expected from them during that phase and its purpose. The many other critical aspects around the practicalities of debriefng, which are “the what, who, when, where, and how to debrief”, are individually explored to provide clear advice with support of relevant references. Of notable importance in this section is the clear description of the most common education performance review approaches (directive feedback, plus/delta, after action review, structured debriefing, etc.) so the most appropriate one can be selected depending on various parameters such as the learning objectives being addressed, the level of expertise of the participants, and the time available.

A comparison of the performance of various project control methods using earned value management systems

Recent literature on project management has emphasised the effort which is spent by the management team during the project control process. Based on this effort, a functional distinction can be made between a top down and a bottom up project control approach. A top down control approach refers to the use of a project control system that generates project based performance metrics to give a general overview of the project performance. Actions are triggered based on these general performance metrics, which need further investigation to detect problems at the activity level. A bottom up project control system refers to a system in which detailed activity information needs to be available constantly during the project control process, which requires more effort. In this research, we propose two new project control approaches, which combines elements of both top down and bottom up control. To this end, we integrate the earned value management/earned schedule (EVM/ES) method with multiple control points inspired by critical chain/buffer management (CC/BM). We show how the EVM/ES control approach is complementary with the concept of buffers and how they can improve the project control process when cleverly combined. These combined top down approaches overcome some of the drawbacks of traditional EVM/ES mentioned in the literature, while minimally increasing the effort spent by the project manager. A large computational experiment is set up to test the approach against other control procedures within a broad range of simulated dynamic project progress situations.

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I–V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array datasheets, the method finds the best I–V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I–V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulationsof PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.

Numerical Simulation of the Current-Voltage Curve in Dye-Sensitized Solar Cells

A theoretical model based on the numerical integration of the continuity equation for electrons with traplimited density-dependent diffusion and recombination constants is implemented to describe the functioning of dye-sensitized solar cells (DSSC). The application of the model combines recent theory on charge transport in nanocrystalline materials with parameters extracted from five simple measurements: the UV/vis spectrum of the dye in solution, the steady-state current-voltage curve, the open circuit photovoltage versus light intensity curve, photocurrent transient upon switching on an illumination source, and open-circuit voltage decay upon switching off the illumination source. As a novel feature not previously included in this kind of calculations, the model includes an additional term that accounts for the charge transfer from the transparent conducting oxide (TCO) substrate to the electrolyte solution. The general applicability of the model is illustrated by applying it to two different types of cell: a TiO2-based solar cell with an organic solvent electrolyte and a ZnO-based solar cell with a solvent-free electrolyte. It is found that the numerical model is capable of adequately fitting all data for both systems, resulting in quantitative estimates for the main parameters controlling solar cell functioning and efficiency. The results show that it is possible to provide a global description of DSSCs based on fundamental theories for trap-limited transport and recombination using simple experimental techniques available to every solar cell laboratory. The present paper tries to help fill the gap between pure theoreticians and experimentalists working on this kind of system.

Hybrid congestion control for high-speed networks

Nowadays, more and more applications require fast transfer of massive data over networks, and the emergence of high-speed networks provides an ideal solution to this challenge. Due to the limitations of the conservative congestion control algorithm, the standard TCP is no longer appropriate for highspeed networks to efficiently utilize the bandwidth resources. Therefore, several high-speed TCP variants have been suggested to conquer the problem. However, although these protocols perform successfully to improve the bandwidth utilization, they still have the weakness on the performance such as RTT-fairness, TCP-friendliness, etc. In this paper, we propose HCC TCP, a hybrid congestion control algorithm using the synergy of delay- based and loss-based approach for the adaptation to high speed and long distance network environment. The algorithm uses queuing delay as the primary congestion indicator, and adjusts the window to stabilize around the size which can achieve the full utilization of available bandwidth. On the other hand, it uses packet loss as the second congestion indicator, and a loss-based congestion control strategy is utilized to maintain high bandwidth utilization in the cases that the delay-based strategy performs inefficiently in the networks. The two approaches in the algorithm are dynamically transferred into each other according to the network status. We finally perform simulations to verify the properties of the proposed HCC TCP. The simulation results demonstrate HCC TCP satisfies the requirements for an ideal TCP variant in high-speed networks, and achieves efficient performance on throughput, fairness, TCP-friendliness, robustness, etc.

Optimal geometric design of monolithic thin-film solar modules: Architecture of polymer solar cells

In this study the geometrical optimization of monolithically integrated solar cells into serially connected solar modules is reported. Based on the experimental determination of electrodes0 sheet and intermittent contact resistances, the overall series resistance of individual solar cells and interconnected solar modules is calculated. Taking a constant photocurrent generation density into account, the total Joule respectively resistive power losses are determined by a self-consistent simulation according to the 1-diode model. This method allows optimization of the solar module geometry depending on the material system applied. As an example, polymer solar modules based on ITO-electrodes and ITO-free electrodes were optimized with respect to structuring dimensions

Research on Active Suspension Control Strategy Based on The Model With Parameters of Hydraulic System

The disadvantage that ordinary active suspension model is in low accuracy and practicability which is caused by the neglect of actuator motion is brought forth through analyzing the assemble of active suspension. The model including hydraulic system parameters is obtained through building the active suspension hydraulic system model. The weighting coefficient matrix of car body acceleration, suspension deflection, and tyre displacement is determined through analyzing the principle of LQG control and the active suspension LQG control strategy is brought out. The conclusion that active suspension promote more control stability and riding comfort than passive suspension and PID control is made by simulation and comparing with passive suspension and active suspension PID control. The force output amplitude performance of the LQG control is better than the PID control which can be get from the force signals.

روش های کاهش واریانس در روش مونت کارلو

روش شبیهسازی مونت کارلو، روشی برای تقریب زدن انتگرال به کمک اعداد تصادفی میباشند. ایدهی اصلی این روش، تبدیل انتگرال به یک امید ریاضی بر اساس یک تابع چگالی احتمال مشخص، تولید نمونهی تصادفی از این تابع چگالی و استفاده از قانون اعداد بزرگ برای تقریب این امید ریاضی است. در روش مونت کارلو، با تولید دنبالهای از متغیرهای تصادفی، که امید ریاضی آنها برابر با θاست، θبرآورد می شود. میزان کارایی این روش زمانی که متغیر تصادفی دارای واریانس کوچک باشد افزایش می یابد. به روشهایی که میتوانند متغیر تصادفی با امید θو واریانس نسبتا کوچک تولید کنند روشهای کاهش واریانس می گویند. در این مقاله به بررسی روشهای کاهش واریانس می پردازیم.

Simulation of OLEDs with a polar electron transport layer

Organic light-emitting diodes (OLEDs) rely on the use of functional materials with suitable energy levels and mobilities for selective charge carrier injection and transport of one species only at the respective electrode. Until recently, however, the dipolar nature of many organic semiconductors has been largely ignored in this context. In particular, electron transports layers (ETLs) often exhibit spontaneous orientation polarization leading to interfacial charges that modify the electrical potential landscape inside a hetero-layer device. Here we demonstrate that the effect of polar ETLs can be simulated using the well-established Poisson and drift-diffusion formalism, if these interfacial charges are taken into account. Impedance spectroscopy is used in order to validate our approach and to characterize the polarity of the material. Finally, simulations allow to quantify the impact of polar ETLs on device performance.

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