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 presents a fuel cell model supplying three-phase dc/ac inverter. Simulink used as interactive tool to model the proposed fuel cell system. The fuel cell output voltage is proportional to the change of the air (oxidant) pressure, the hydrogen (fuel) pressure and the current withdrawn from the fuel cell. Three-phase dc/ac inverter used to supply the ac load. Symmetric Space Vector Pulse Width Modulation used to drive the three-phase inverter so that minimum harmonic distortion on the load side voltage and current. Simulation results provided to validate the design.

Fuel Cell Model for Three-Phase Inverter

This paper presents the design of a flight path controller for an unmanned aircraft. Innovative control technique based on nested Proportional-Integral-Derivative (PID) loops is introduced in the design. The flight characteristics of the airframe used in the controller development is analyzed using a three degree of freedom point mass equation of motion. Simulation results of flight controller together with aircraft dynamics are demonstrated in order to show and validate the effectiveness of the proposed controller.

Design of an autonomous unmanned aircraft flight path controller

The application of boost converters is highly favored in PV module integrated converter (MIC) systems. The conventional boost converter operating in continuous inductor-current mode (CICM), however, has a pulsating, high-ripple input current, which causes power loss and decreases the energy flowing from non-linear sources like the PV panel. Therefore, this paper proposes a new modified boost converter that has a no-ripple input current. The proposed converter uses a series of input inductance to produce zero-ripple input current during continuous inductor-current mode, without any LC or C filter elements. It is capable of high power-conversion efficiency for the whole system without the use of any transformer or galvanic isolation components. In addition, this proposed boost converter is integrated with an H-Bridge inverter for a transformerless PV grid-connected system. The issue of electrical safety of the high ground-leakage current (due to the parasitic capacitance of the PV panel and frame and lack of galvanic isolation) is resolved by bipolar SPWM technique in the H-Bridge inverter, without any additional hardware. The proposed DC-AC transformerless inverter grid-connected PV system, which has a new modified boost converter and bipolar H-Bridge inverter, is verified by a 1-kW hardware prototype simulated and validated by experiment. The results show zero-ripple input current, high power-conversion efficiency, near-unity power factor, low current-THD, and low ground-leakage current.

Transformerless power converter for grid-connected PV system with no-ripple input current and low ground-leakage current

Aromatic rice (Oryza sativa L.) is considered as the best quality premium rice. The varieties are preferred by consumers because of its preference criteria such as shape, colour, distinctive aroma and flavour. The price of aromatic rice is higher than ordinary rice due to its special needed growth condition for instance specific climate and soil. Presently, the aromatic rice quality is identified by using its key elements and isotopic variables. The rice can also be classified via Gas Chromatography Mass Spectrometry (GC-MS) or human sensory panels. However, the uses of human sensory panels have significant drawbacks such as lengthy training time, and prone to fatigue as the number of sample increased and inconsistent. The GC–MS analysis techniques on the other hand, require detailed procedures, lengthy analysis and quite costly. This paper presents the application of in-house developed Electronic Nose (e-nose) to classify new aromatic rice varieties. The e-nose is used to classify the variety of aromatic rice based on the samples odour. The samples were taken from the variety of rice. The instrument utilizes multivariate statistical data analysis, including Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA) and K-Nearest Neighbours (KNN) to classify the unknown rice samples. The Leave-One-Out (LOO) validation approach is applied to evaluate the ability of KNN to perform recognition and classification of the unspecified samples. The visual observation of the PCA and LDA plots of the rice proves that the instrument was able to separate the samples into different clusters accordingly. The results of LDA and KNN with low misclassification error support the above findings and we may conclude that the e-nose is successfully applied to the classification of the aromatic rice varieties.

Classification of Malaysia aromatic rice using multivariate statistical analysis

This study presents the design and performance analysis of a prototype axial-flux permanent-magnet (AFPM) synchronous machine. First, the design of AFPM machine is optimised by genetic algorithm based sizing equation and finite element analysis. The design objectives of this machine are maximum power density, minimum total harmonic distortion (THD) of the sinusoidal back-electromotive force (back-EMF) waveform and low cogging torque. Based on the optimised design of the machine a prototype 1 kW, three-phase, 50 Hz, four-pole AFPM synchronous machine is built. Then, the performance of the prototype machine is tested to see the cogging torque, torque–speed characteristic, efficiency and the THD of the induced voltage. It is found that the prototype machine validates the design in terms of high-power density, lowest possible THD of the back-EMF, low cogging torque while maintaining high efficiency.

Nasrudin Abd Rahim

Papers

Fuel Cell Model for Three-Phase Inverter

Design of an autonomous unmanned aircraft flight path controller

Transformerless power converter for grid-connected PV system with no-ripple input current and low ground-leakage current

Classification of Malaysia aromatic rice using multivariate statistical analysis

Design and prototyping of an optimized axial flux permanent magnet synchronous machine