3 research outputs found
An E.S.R. spectrometer for the study of transient paramagnetic species
Get PDFThis thesis is concerned with a description of work carried out in the design, development and use of suitable equipment to be utilised with an Electron Spin Resonance Spectrometer and a Computer of Average Transients in order to record E.S.R. spectra of transient paramagnetic species. The first part of the thesis contains a basic outline of the theory of E.S.R. and a description and discussion of E.S.R. spectrometers. There follows a discussion on signal to noise considerations with particular emphasis on the device known as the phase sensitive detector (P.S.D.) with a natural transition to averaging systems which play an important part in a rapid recording spectrometer. An explanatory review of various methods of recording data on transient paramagnetic species is included, along with the reasons for the development of the particular system utilised by the author. A description of the apparatus used is included with a detailed description of the design, development and testing of the information processing equipment. A brief analysis of the E.S.R. spectra of atomic oxygen is given, followed by a description and discussion of the results obtained on the kinetics of their formation and decay processes, in an r.f. discharge, observed as a test sample for an assessment of the equipment.The concluding chapter discusses the relative merits of the author's system in particular and the advantages and disadvantages of rapid recording systems in general. A final discussion of the possible improvements and alternative versions of the present system is included, along with a technique using an on line computer in conjunction with a fast record slow playback (F.R.S.P.) device to record and present all the relevant data as a “3 dimensional" display
The correlation between reading and mathematics ability at age twelve has a substantial genetic component.
Get PDFDissecting how genetic and environmental influences impact on learning is helpful for maximizing numeracy and literacy. Here we show, using twin and genome-wide analysis, that there is a substantial genetic component to children's ability in reading and mathematics, and estimate that around one half of the observed correlation in these traits is due to shared genetic effects (so-called Generalist Genes). Thus, our results highlight the potential role of the learning environment in contributing to differences in a child's cognitive abilities at age twelve
FIELD-ORIENTED CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR DRIVE SYSTEM USING MATRIX CONVERTER
Get PDFIn this paper a Field-Oriented Control of permanent magnet synchronous motor (PMSM) drive system using adapted hysteresis current control based on matrix converter is presented. The matrix converter is an arrangement of controlled semiconductor switches that connects directly the three-phase source to the three-phase load. This converter has several attractive features that have been research in the last two decades. To increase use of input voltage assets, input voltages are split into 12 divisions within one cycle. A adapted current controller collected of two nested current hysteresis control is evaluate in details. According to the outputs of current controller and division of input voltages, a proper input voltage must be selected to increase or decrease output current of matrix converter. The division table is evaluate and moderately deduced. Finally, simulation system is designed. Simulating results illustrate that Field-Oriented Control of PMSM drive system using adapted hysteresis current control based on matrix converter has the quality of practicability and efficiency, which brings out theoretical fundamentals of experimentation
