Extended fundamental frequency analysis of the LCC resonant converter

Fundamental frequency techniques are used to analyze the series-parallel resonant converter under heavy load conditions, both with a continuous, but distorted parallel capacitor voltage waveform, and with a discontinuous capacitor voltage waveform. The analysis is validated with results from an experimental prototype. The application of the technique to the parallel-loaded L-C resonant converter is also considered.     

The design of experiments when there are errors in all the variables

The Error-in-Variables Model (EVM) applies to a large class of problems in parameter estimation in which there is error in all the variables. This property makes it of more general applicability than the widely used technique of ordinary Least Squares. While there is a voluminous literature on EVM there is nothing on a general method for designing experiments when EVM applies. In this paper we present an extension of the concept of D-optimality to provide such a general method. It is illustrated by applying it to the estimation of copolymer reactivity ratios and to fitting an ellipse.     

MR monitoring of focused ultrasonic surgery of renal cortex: experimental and simulation studies

The aim of the study was to test the hypothesis that magnetic resonance (MR) imaging-guided and -monitored noninvasive ultrasonic surgery can be performed in highly perfused tissues from outside the body. A simulation study was performed to evaluate the optimal sonication parameters. An MR-compatible positioning device was then used to manipulate a focused ultrasound transducer in an MR imager, which was used to sonicate kidneys of five rabbits at various power levels and different durations. Temperature elevation during sonication was monitored with a T1-weighted spoiled gradient-echo sequence. The simulation study demonstrated that a sharply focused transducer and relatively short sonication times (30 seconds or less) are necessary to prevent damage to the overlying skin and muscle tissue, which have a much lower blood perfusion rate than kidney. The experiments showed that the imaging sequence was sensitive enough to show temperature elevation during sonication, thereby indicating the location of the beam focus. Histologic evaluations showed that kidney necrosis could be consistently induced without damage to overlying skin and muscle. The study demonstrated that highly perfused tissues such as the renal cortex can be coagulated from outside the body with focused ultrasound and that MR imaging can be used to guide and monitor this surgery.     

Degradation of junction leakage in devices subjected to gateoxidation in nitrous oxide [MOS transistors]

Nitrided gate oxides offer several electrical and reliability advantages over conventional oxides and also provide a good barrier against impurity diffusion. Oxidation in nitrous oxide (N₂O) has been very successful in overcoming some of the problems associated with nitridation in ammonia. The authors have observed that the extent of N₂O oxidation has a strong detrimental effect on the drain leakage current of MOS transistors in the off state. This phenomenon has been identified to be caused by an increase in the active area junction leakage current     

Crystallization and melting behaviour of poly(butylene terephthalate) in poly(butylene terephthalate)/polyarylate blends

Summary The crystallization and melting behaviour of poly(butylene terephthalate) has been studied in the pure state and in its blends with a polyarylate of bisphenol A and isophthalic/terephthalic acids. Differential scanning calorimetry has been used as experimental technique and the effects of different thermal treatments have been analyzed. Results show the hindrance for the crystallization of poly(butylene terephthalate) imposed by the presence of polyarylate, as well as the existence of multiple melting after isothermal crystallization. Explanations are given for the observed behaviours.     

Markov decision processes with delays and asynchronous cost collection

Markov decision processes (MDPs) may involve three types of delays. First, state information, rather than being available instantaneously, may arrive with a delay (observation delay). Second, an action may take effect at a later decision stage rather than immediately (action delay). Third, the cost induced by an action may be collected after a number of stages (cost delay). We de rive two results, one for constant and one for random delays, for reducing an MDP with delays to an MDP without delays, which differs only in the size of the state space. The results are based on the intuition that costs may be collected asynchronously, i.e., at a stage other than the one in which they are induced, as long as they are discounted properly.     

Phase Relations and Properties of Phases in the TlInSe2–TlPrSe2 System

The phase diagram of the TlInSe₂–TlPrSe₂ system was mapped out using differential thermal analysis and x-ray diffraction data. The system was found to contain a partial solid-solution series (0–10 mol % TlPrSe₂) and a quaternary compound of composition Tl₂InPrSe₄. The electrical conductivity, Hall coefficient, and thermoelectric power of TlPrSe₂ and Tl₂InPrSe₄ were measured in the temperature range 300–1100 K. The charge carriers in these compounds were shown to be scattered mainly by longitudinal acoustic phonons.