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

1. Interaction. The interactions learners have with each other build interpersonal skills, such as listening, politely interrupting, expressing ideas, raising questions, disagreeing, paraphrasing, negotiating, and asking for help. 2. Interdependence. Learners must depend on one another to accomplish a common objective. Each group member has specific tasks to complete, and successful completion of each member’s tasks results in attaining the overall group objective.

将“Cooperative Learning”融入课堂——浅谈英语素质教育

Solar Engineering Of Thermal Processes

The recently introduced proportional-resonant (PR) controllers and filters, and their suitability for current/voltage control of grid-connected converters, are described. Using the PR controllers, the converter reference tracking performance can be enhanced and previously known shortcomings associated with conventional PI controllers can be alleviated. These shortcomings include steady-state errors in single-phase systems and the need for synchronous d-q transformation in three-phase systems. Based on similar control theory, PR filters can also be used for generating the harmonic command reference precisely in an active power filter, especially for single-phase systems, where d-q transformation theory is not directly applicable. Another advantage associated with the PR controllers and filters is the possibility of implementing selective harmonic compensation without requiring excessive computational resources. Given these advantages and the belief that PR control will find wide-ranging applications in grid-interfaced converters, PR control theory is revised in detail with a number of practical cases that have been implemented previously, described clearly to give a comprehensive reference on PR control and filtering.

Proportional-resonant controllers and filters for grid-connected voltage-source converters

Recent advancements in supercapacitor technology

People usually spend most of the time inside buildings. Therefore, it is necessary to reach an optimal thermal comfort situation since thermal comfort has a direct effect on people's productivity. The use of appropriate control strategies can highly contribute to this purpose. Usually the own people's influence is not taken into account at the time to maintain an optimal thermal comfort. People enter and leave the building following certain pattern which is repeated from one day to another. This paper presents a Repetitive Control (RC) approach which can counteract this periodic behaviour. This controller anticipates the effects produced by the entries and outputs of the people. Moreover, this controller is complemented by a feedback controller in order to cancel the non periodic disturbances. Simulation results obtained from the application of this control strategy to a characteristic room of a building are included and commented.

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Repetitive control to counteract the effect of people on thermal comfort control

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H∞ interactive controller design for teaching purposes

In the current context of increasing global energy needs and the depletion of traditional energy sources are particularly relevant management processes and the energy use improving. To contribute to the dissemination of these processes our institution has developed a project that aims to development a set of virtual laboratories to introduce these processes to engineering students. This paper presents an environment designed to illustrate the energy management ideas used in a metropolitan transportation system.

Virtual Laboratory for the dissemination of energy management systems. The case of the metropolitan transport system

The tracking/rejection of periodic disturbances in linear systems is achievable via internal model principle-based techniques, such as repetitive control. However, when the frequency of the signal to track/reject is uncertain or time-varying, the performance of these controllers decays dramatically. This article discusses the basics of Model Reference Adaptive Control with Minimal Controller Synthesis, and assesses its applicability to this problem from a comparative study of the performance of this type of controllers and a repetitive controller, both designed to regulate the speed of a DC motor subject to periodic disturbances. The study is supported by experimental results.

/pdf/rejection-of-periodic-disturbances-using-mrac-with-minimal-1rmjpb7wcf.pdf

Rejection of periodic disturbances using MRAC with minimal controller synthesis

This work presents the preliminary findings of a feasibility study for a class of sliding mode differentiators to be used in an on-line parameter estimation methodology for vanadium redox flow batteries (VRFB). Specifically, three high-order continuous differentiators are considered: a Standard Differentiator; a Filtering Differentiator, which excels the former by incorporating rejection to large noises small in average; and a Tracking Filtering Differentiator, which produces smooth consistent derivatives while inheriting the noise rejection capabilities from the previous one. To model the vanadium redox flow batteries an equivalent circuit model is employed, whose time-varying parameters are estimated by a recursive least squares algorithm with forgetting factor, that requires the VRFB measured voltage and current, together with their derivatives. To assess the performance of the different differentiation algorithms in obtaining reliable values of the VRFB parameters, the storage system is excited with standardised current demand profiles. Finally, representative simulation results are presented and discussed.

Ramon Costa-Castelló

Papers

Repetitive control to counteract the effect of people on thermal comfort control

H∞ interactive controller design for teaching purposes

Virtual Laboratory for the dissemination of energy management systems. The case of the metropolitan transport system

Rejection of periodic disturbances using MRAC with minimal controller synthesis

Feasibility analysis of a class of high-order sliding-mode differentiators for redox flow batteries parameter estimation