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

To study the operational behaviour of λ-terms, we will use the denotational (mathematical) approach. A denotational semantics for a language is based on the choice of a space of semantics values, or denotations, where terms are to be interpreted. Choosing a space with nice mathematical properties can help in proving the semantic properties of terms, since to this aim standard mathematical techniques can be used.

λ Δ -Models

Public awareness of the need to reduce global warming and the significant increase in the prices of conventional energy sources have encouraged many countries to provide new energy policies that promote the renewable energy applications. Such renewable energy sources like wind, solar, hydro based energies, etc. are environment friendly and have potential to be more widely used. Combining these renewable energy sources with back-up units to form a hybrid system can provide a more economic, environment friendly and reliable supply of electricity in all load demand conditions compared to single-use of such systems. One of the most important issues in this type of hybrid system is to optimally size the hybrid system components as sufficient enough to meet all load requirements with possible minimum investment and operating costs. There are many studies about the optimization and sizing of hybrid renewable energy systems since the recent popular utilization of renewable energy sources. In this concept, this paper provides a detailed analysis of such optimum sizing approaches in the literature that can make significant contributions to wider renewable energy penetration by enhancing the system applicability in terms of economy.

Optimum design of hybrid renewable energy systems: Overview of different approaches

The demand for electricity is increasing day by day, which cannot be fulfilled by non-renewable energy sources alone. Renewable energy sources such as solar and wind are omnipresent and environmental friendly. The renewable emulnergy sources are emerging options to fulfill the energy demand, but unreliable due to the stochastic nature of their occurrence. Hybrid renewable energy system (HRES) combines two or more renewable energy sources like wind turbine and solar system. The objective of this paper is to present a comprehensive review of various aspects of HRES. This paper discusses prefeasibility analysis, optimum sizing, modeling, control aspects and reliability issues. The application of evolutionary technique and game theory in hybrid renewable energy is also presented in this paper.

Solar–wind hybrid renewable energy system: A review

Online fault diagnosis plays a crucial role in providing the required fault tolerance to drive systems used in safety-critical applications. Short-circuit faults are among the common faults occurring in electrical machines. This paper presents a review of existing techniques available for online stator interturn fault detection and diagnosis (FDD) in electrical machines. Special attention is given to short-circuit-fault diagnosis in permanent-magnet machines, which are fast replacing traditional machines in a wide variety of applications. Recent techniques that use signals analysis, models, or knowledge-based systems for FDD are reviewed in this paper. Motor current is the most commonly analyzed signal for fault diagnosis. Hence, motor current signature analysis is a topic of elaborate discussion in this paper. Additionally, parametric and finite-element models that were designed to simulate interturn-fault conditions are reviewed.

Recent Advances in Modeling and Online Detection of Stator Interturn Faults in Electrical Motors

This paper describes the skewed analytical model of an axial flux permanent magnet synchronous machine (AFPMSM) for further optimization process of a 10 kW/130 rpm slotted axial flux machine dedicated to wind energy application. The proposed model is based on the exact 2D solution of the magnetic field in the generator by solving the Maxwell's equations. This approach is very helpful to calculate accurately the magnetic field distribution in the machine with a reasonable computation time. The global quantities of the machine (inductances, EMF) are then calculated by using the winding functions technique. The developed model is finally used to study the influence of skewing on the main quantities (EMF, cogging torque, main torque) of a 10 kW/130 rpm, 14 poles AFPMSM dedicated for wind energy applications.

Influence of skewing on the performances of an axial flux PM wind generator coupled to a diode rectifier

This paper presents a design optimization of an axial flux permanent magnet synchronous machine (AFPMSM). The design optimization is performed using separately two different algorithms: a deterministic algorithm and a stochastic algorithm. The used DIRECT algorithm and genetic algorithm (GA) are described and tested separately to optimize a 10kW / 130 rpm AFPMSM. The obtained results by the two algorithms are compared in terms of precision of the found global optimum, convergence speed and simplicity of implementation. In particular, optimal design results show the effectiveness of DIRECT algorithm.

Design Optimization of an Axial Flux PM Synchronous Machine: Comparison Between DIRECT Method and GAs Method

In this paper a methodology for calculation of the optimum size of a stand-alone hybrid wind/photovoltaic (wind/PV) system is developed. The collection of six months of data of wind speed and ambient temperature recorded for every hour of the day and an estimate of solar irradiance were used. These data and manufacturer's specifications on a wind turbine and a PV module were used to calculate the average power generated by the wind turbine and the PV module for each hour of the day. A deterministic algorithm is used to minimize the life cycle cost of the system while guaranteeing the satisfaction of the load. The mathematical modeling of the principal elements of the hybrid wind/PV system is exposed showing the main sizing variables. The deterministic algorithm is presented and implemented to minimize the objective function.

Modeling and optimization of wind/PV system for stand-alone site

Flux-Switching machines (FSM) have been gaining attention during the last decade. Their electromagnetic behavior has been extensively studied for various topologies, i.e. U-core and E-core, simple (wound field or PM) and hybrid excitations FSM machines. Even though noise and vibrations of electromagnetic origins can be important drawbacks, depending on the application, only few studies are analyzing these aspects. As a result, this paper aims at understanding the sound power level of U-core flux-switching permanent magnet (FSPM) machines whose rotors have different number of poles. The stator of the extensively studied 12/10 stator/rotor pole FSPM machine (12s10rp) serves as a basis for investigating 12s11rp, 12s13rp and 12s14rp configurations. Electromagnetic pressure is calculated from the Maxwell stress tensor where the magnetic flux density is obtained with 2-D finite element analysis (FEA). It then serves as input of a mechanical and acoustical 3-D FEA model of the stator with carter.

Impact of pole and slot combination on noise and vibrations of flux-switching PM machines

The goal of this paper is to review generator systems used in wind turbines and to determine suitable generator concepts for future high power wind turbines. An up to date state of the art of wind turbine generators is first presented. It will help, through a critical analysis, to identify limiting constraints to power rating increase of wind turbine generator systems. Finally, some potential solutions are discussed.

Georges Barakat

Papers

Influence of skewing on the performances of an axial flux PM wind generator coupled to a diode rectifier

Design Optimization of an Axial Flux PM Synchronous Machine: Comparison Between DIRECT Method and GAs Method

Modeling and optimization of wind/PV system for stand-alone site

Impact of pole and slot combination on noise and vibrations of flux-switching PM machines

Overview of high power wind turbine generators