There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.

A review of single-phase grid-connected inverters for photovoltaic modules

This paper discusses the control technique improvement of a three-phase inverter using directquadrature-
zero (d-q-0) controller based on DSP TMS320F2812 for dynamic voltage restorer (DVR)
applications. The output of the inverter is then connected to a voltage grid via a second order filter and
injection transformer. The control algorithms are developed using TMS320F 2812 DSP. The proposed
technique achieves voltage regulation with low total harmonics distortion (THD) for both voltage and
current. This paper also highlights a series of discussion, analysis and studies performed on the
proposed control technique, including L-C filter design issue and the concept of DVR in the distribution
system. An analysis and experimental results validate the effectiveness of the DSP controller in
mitigating voltage sags and harmonics issues in the distribution system

https://www.academicjournals.org/article/article1380789290_Omar and Rahim.pdf

Three phase inverter control using DSP controller for dynamic voltage restorer (DVR) application

This paper presents the design process of a novel axial-flux permanent-magnet (AFPM) motor capable of auto-starting. The preliminary design is a slot-less double-sided solid-rotor line-start AFPM motor with 4 poles for high torque density and stable rotation. One spaced raised ring was added to the inner radii of the rotor disc for smooth line-start motor. The design allows the motor to operate at both starting and synchronous speeds. The basic equations for the solid ring of the rotor for the proposed axial-flux permanent-magnet motor are presented. Non-symmetry of the designed motor led to its 3D time-stepping finite element analysis (FEA), which is used to evaluate the design parameters and predict the transient performance. The designed motor was fabricated and tested; sample experimental result showed good agreement with those of FEA based simulated results. The prototype motor showed excellent characteristics (high starting torque, good synchronization), and excellent steady-state performance.

Line-start axial-flux permanent-magnet synchronous motor

Direct torque control (DTC) is considered as the best alternative for permanent magnet synchronous (PMSM) drives. Classic switching-table based DTC has high torque and flux ripple due to the implementation of hysteresis control. Switching frequency can be made constant by replacing hysteresis control with space vector PWM (SVM) and requires mathematical modification on SVM input. Propotional+integral control and reference flux vector calculation (RFVC) is used to improve the torque response, flux and torque ripple. These scheme still utilizing similar torque and flux estimator as introduced in classic DTC. Propotional+integral control DTC performed better in term of torque step response whilst RFVC torque and flux ripple are the best among these three schemes.

Switching-table and space vector modulation direct torque control of permanent magnet synchronous motor drives simulation

This paper presents a new schematic for three phase seven-level inverters. The proposed topology minimizes switching, reduces short circuiting, is easy to control, and can mask through upper-level switches the work of lower levels. System improvements include low ripple-current, high power conversion and minimized switching, which are verified in simulations using the Matlab/Simulink software package. Experimental results are obtained through the use of field programmable gate arrays (FPGA), and the pulse generation is carried out using the SPARTAN 3A DSP board. The proposed topology has been experimentally implemented for both five-level and seven-level pulse width modulated laboratory inverters.

Nasrudin Abd Rahim

Papers

Three phase inverter control using DSP controller for dynamic voltage restorer (DVR) application

Line-start axial-flux permanent-magnet synchronous motor

Switching-table and space vector modulation direct torque control of permanent magnet synchronous motor drives simulation

New topology three phase multilevel inverter for grid-connected photovoltaic system

Switching Functions Model of a Three-phase Voltage Source Converter (VSC)