Generalized small-signal modelling of dual active bridge DC/DC converter

this paper presents a novel generalised approach of the small-signal modelling of dual active bridge (DAB) DC/DC converter. The adopted analysis is based on a per-unit fundamental frequency representation of the DAB. The outcome of the proposed modelling approach is a small signal, linearised, state-space DAB model; which is considered as a main building block for future control applications. The developed small signal DAB model includes all possible degrees of freedom affecting the performance of the DAB; this includes the voltage conversion ratio to allow the study of all DAB operation modes (i.e.: unity-gain and buck/boost modes.). Furthermore, since triple phase shift control (TPS) is used in this development work, the proposed model incorporates phase shift in addition to duty ratios. This feature allows for bridge voltage regulation, which is essential for efficient DAB operation in the case of buck/boost operation. Another key achievement is that the proposed small signal modelling methodology can be applied to any bidirectional DC-DC converter regardless of ratings, parameter values and number of ports. Extensive simulation is carried out to verify the proposed analysis

The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.Comment: 8 pages, 12 figures, Data presented at 2006 NSREC, Final Version to be published in IEEE Transactions on Nuclear Science, 53, NO. 6, December 2006. Index Terms: GaAs, Ion-irradiation, Lithium, NIEL, Photovoltaic cells, Radiation effects, Silico

An improved method for the synthesis of cyclopropyl ketoesters

A simple and versatile method for the synthesis of cyclopropyl ketoesters starting from chalcones and ethyl cyanoacetate in benzene using sodium powder as base is described

Unusually heavy catches of ribbon fish close to the shore at Visakhapatnam

Very heavy catches of ribbonfish were observed quite close to the shore at Visakhapatnam for a very short duration. Observations were made on this fishery and certain important biological aspects Ribbonfish do not generally come very close to the shore. As such they are vei7 rarely caught in the shore-seines. They are normally caught in boatseines operating 3-4 km away from the shore and in trawl nets. It is possible that the ribbon fish shoal after spawning hit the shore chasing their food consisting of Stolephorus sp, Leiognathus sp. Etc. Which might have been moving closer to the Shore to avoid the cold upwelled water

Magnetic studies of Bi x Y3-x Fe5O12 fabricated using conventional method

A series of Bi substituted yttrium iron garnet (Bi-YIG) nanoparticles with nominal formula of BixY3 − xFe5O12 in which x varied in steps of 0.0, 0.25 and 0.5 are prepared by conventional method. Vibration sample magnetometer (VSM) at Room temperature (RT) shows saturation magnetization decreases from 27.4 to 25.2 (emu/g) as x value increases from 0.0 to 0.5. Room temperature 57Fe Mössbauer spectra are recorded for these series. The hyperfine field value for octahedral and tetrahedral of samples increases from 484 and 390 kOe to 491 and 397 kOe respectability, as Bi replaces Y in (BixY3 − xFe5O12) atom with increasing x value. The effect of Bi3 +  substitution for Y3 +  on lattice constants, morphology and magnetic properties of pure YIG has been investigated

Tunneling and Non-Universality in Continuum Percolation Systems

The values obtained experimentally for the conductivity critical exponent in numerous percolation systems, in which the interparticle conduction is by tunnelling, were found to be in the range of $t_0$ and about $t_0+10$, where $t_0$ is the universal conductivity exponent. These latter values are however considerably smaller than those predicted by the available ``one dimensional"-like theory of tunneling-percolation. In this letter we show that this long-standing discrepancy can be resolved by considering the more realistic "three dimensional" model and the limited proximity to the percolation threshold in all the many available experimental studiesComment: 4 pages, 2 figure

Testing Point Null Hypothesis of a Normal Mean and the Truth: 21st Century Perspective

Testing a point (sharp) null hypothesis is arguably the most widely used statistical inferential procedure in many fields of scientific research, nevertheless, the most controversial, and misapprehended. Since 1935 when Buchanan-Wollaston raised the first criticism against hypothesis testing, this foundational field of statistics has drawn increasingly active and stronger opposition, including draconian suggestions that statistical significance testing should be abandoned or even banned. Statisticians should stop ignoring these accumulated and significant anomalies within the current point-null hypotheses paradigm and rebuild healthy foundations of statistical science. The foundation for a paradigm shift in testing statistical hypotheses is suggested, which is testing interval null hypotheses based on implications of the Zero probability paradox. It states that in a real-world research point-null hypothesis of a normal mean has zero probability. This implies that formulated point-null hypothesis of a mean in the context of the simple normal model is almost surely false. Thus, Zero probability paradox points to the root cause of so-called large n problem in significance testing. It discloses that there is no point in searching for a cure under the current point-null paradigm

A qualitative test for the determination of isoniazid acetylator phenotype

A qualitative test procedure for phenotyping isoniazid acetylators is described. It is based on a colour reaction which depends on the free sulphadimidine content in the total urine excreted over any one-hour period between 21 and 26 hours following a dose of sulphadimidine 1.0 or 1.5 g. depending on body-weight. The test correctly classified 96 per cent of 109 slow and 96 per cent of 68 rapid inactivators. Storage of urine samples at room-temperature up to 14 days did not affect the accuracy of the results