다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

Renewable energy sources like wind, sun, and hydro are seen as a reliable alternative to the traditional energy sources such as oil, natural gas, or coal. Distributed power generation systems (DPGSs) based on renewable energy sources experience a large development worldwide, with Germany, Denmark, Japan, and USA as leaders in the development in this field. Due to the increasing number of DPGSs connected to the utility network, new and stricter standards in respect to power quality, safe running, and islanding protection are issued. As a consequence, the control of distributed generation systems should be improved to meet the requirements for grid interconnection. This paper gives an overview of the structures for the DPGS based on fuel cell, photovoltaic, and wind turbines. In addition, control structures of the grid-side converter are presented, and the possibility of compensation for low-order harmonics is also discussed. Moreover, control strategies when running on grid faults are treated. This paper ends up with an overview of synchronization methods and a discussion about their importance in the control

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Overview of Control and Grid Synchronization for Distributed Power Generation Systems

DC and AC Microgrids are key elements to integrate renewable and distributed energy resources as well as distributed energy storage systems. In the last years, efforts toward the standardization of these Microgrids have been made. In this sense, this paper present the hierarchical control derived from ISA-95 and electrical dispatching standards to endow smartness and flexibility to microgrids. The hierarchical control proposed consist of three levels: i) the primary control is based on the droop method, including an output impedance virtual loop; ii) the secondary control allows restoring the deviations produced by the primary control; and iii) the tertiary control manage the power flow between the microgrid and the external electrical distribution system. Results from a hierarchical-controlled microgrid are provided to show the feasibility of the proposed approach.

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Hierarchical control of droop-controlled DC and AC microgrids — a general approach towards standardization

The use of distributed energy resources is increasingly being pursued as a supplement and an alternative to large conventional central power stations. The specification of a power-electronic interface is subject to requirements related not only to the renewable energy source itself but also to its effects on the power-system operation, especially where the intermittent energy source constitutes a significant part of the total system capacity. In this paper, new trends in power electronics for the integration of wind and photovoltaic (PV) power generators are presented. A review of the appropriate storage-system technology used for the integration of intermittent renewable energy sources is also introduced. Discussions about common and future trends in renewable energy systems based on reliability and maturity of each technology are presented

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Power-Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey

The integration of renewable energies and electric vehicle (EV) charging stations is challenging the electric grid in terms of resonances caused by complex interaction mechanisms involving power convertor control and electromagnetic transients of the grid. Very often, these problems have been tackled with decentralized control approaches, which have difficulties in taking all the interdependencies into consideration. This article proposes a different perspective: a centralized control approach through a smart transformer (ST). 

Stabilization of Distribution Grids With High Penetration of Renewables: The Path From Decentralized Control to a Centralized One

When unbalances happen among the cells of a cascaded H-bridge (CHB) converter, variable angle phase-shifting (VAPS) pulse-width modulation (PWM) methods can be employed to improve the total harmonic distortion (THD) performance. However, as conventional methods are based on optimization algorithms which require a huge amount of evolutionary computations, the optimal carrier phase-shifting (PS) angles cannot be timely updated with a common standard digital signal processor (DSP) or microcontroller. During the period when the optimization is not finished, the THD of the total output voltage may significantly increase, bringing about higher power losses. Thus, a computation-efficient VAPS PWM method is proposed in this paper. With multiple calculation units (CUs) implemented in field programmable gate arrays (FPGAs), multiple calculations can be executed in parallel, significantly improving the optimization speed of the VAPS PWM method. Experimental results on a 4-cell CHB converter have demonstrated the effectiveness of the proposed method.

Computation-Efficient Variable Angle Phase-Shifting PWM Method for Cascaded H-Bridge Converters

The 34 articles in this special section are selected papers from the 2010 IEEE International Symposium on Industrial Electronics that was held in Bari, Italy, on July 4-7, 2010.

Introduction to the Special Section on the 2010 IEEE International Symposium on Industrial Electronics

A simultaneous wireless information and power transfer system employing separated frequency bands for energy and data, dubbed dual-band SWIPT, is investigated. Elementary circuit elements are optimized numerically. An experimental testbed based on a gallium nitride (GaN) full-bridge converter demonstrates data rates in excess of 450 kbps employing on-off keying in conjunction with a simple diode detector for data recovery.

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Simultaneous Wireless Information and GaN-Based Power Transfer Exploiting a Dual Frequency Band

Low power system inertia in power electronics-dominated grids is a widely discussed problem. Power synchronization allows to emulate inertia by means of the active power low-pass filter, slowing down the grid frequency excursions. Nevertheless, inertia emulation during grid disturbances results in high energy exchange with the dc-link, which brings large dc voltage excursions. When the dc voltage dips below the ac line voltage peak, the modulation index can become too high and make the converter unable to produce the requested ac voltage. The consequent saturation of the voltage can cause current control wind-up, harmonic distortion and loss of controllability. Moreover, when the reference voltage is saturated, the converter does not behave anymore according to the power synchronization control law, making the conventional stability analyses not valid. Despite the relevance of these issues, a systematic analysis about the voltage saturation induced by grid disturbances in power converters is still missing. For that, this paper proposes a mathematical tool based on Bode plots. The target of this tool is to properly chose the converter parameters in order to tolerate grid disturbances without reaching the voltage saturation. Simulations and experiments are provided.

Marco Liserre

Papers

Stabilization of Distribution Grids With High Penetration of Renewables: The Path From Decentralized Control to a Centralized One

Computation-Efficient Variable Angle Phase-Shifting PWM Method for Cascaded H-Bridge Converters

Introduction to the Special Section on the 2010 IEEE International Symposium on Industrial Electronics

Simultaneous Wireless Information and GaN-Based Power Transfer Exploiting a Dual Frequency Band

Analysis of Overmodulation in Power Synchronization-based Voltage Source Converters