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

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

LPAR1 (lysophosphatidic acid receptor 1)

Review on LPAR1 (lysophosphatidic acid receptor 1), with data on DNA, on the protein encoded, and where the gene is implicated

ENHANCEMENT OF SOLUBILITY AND DISSOLUTION RATE OF ACETYLSALICYLIC ACID VIA CO-CRYSTALLIZATION TECHNIQUE: A NOVEL ASA-VALINE COCRYSTAL

Objective: This study aims to synthesize acetylsalicylic acid (ASA) cocrystals using valine as a coformer via a co-crystallization technique to increase the solubility and dissolution rate of ASA. Methods: The ASA-valine cocrystal (1:1 molar ratio) was prepared using the solvent evaporation technique with ethanol: water (50:50). The cocrystal was characterized using Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), melting point to confirm the formation of cocrystal. The evaluation of cocrystal was done by drug content determination, solubility and dissolution studies. Results: The prepared cocrystal was successfully confirmed for the formation of a hydrogen bond. The melting point of prepared cocrystal was decreased compared to pure ASA and valine, which indicated the formation of a new crystalline form. The FT-IR studies showed the formation of a new hydrogen bond by shifting the-O-H,-C=O and-N-H functional groups. SEM studies ensured that the prepared cocrystals were in needle-like appearance. Finally, DSC and PXRD studies were also indicated the successful formation of ASA-valine cocrystal. The drug release of cocrystal was found to be 100% at 60th min. Where in the case of pure ASA and marketed product of ASA exhibited the dissolution rate of 59% and 69% at 60th min respectively. Conclusion: The co-crystallization technique can be adopted as the best strategy to increase the solubility and dissolution rate of BCS class 2 drugs. Therefore the prepared ASA-valine cocrystal can be a greater alternative to increase the solubility and dissolution rate compared with pure and marketed ASA

Test of the DWBA Description of Transfer Reactions at Intermediate Energies by Measuring a Complete Set of Single Nucleon and Elastic Scattering Data

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

The 3s Proton Occupancy in 206-Pb

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Investigation of pulsed laser induced dewetting in nanoscopic metal films

Hydrodynamic pattern formation (PF) and dewetting resulting from pulsed laser induced melting of nanoscopic metal films have been used to create spatially ordered metal nanoparticle arrays with monomodal size distribution on SiO_{\text{2}}/Si substrates. PF was investigated for film thickness h\leq7 nm < laser absorption depth \sim11 nm and different sets of laser parameters, including energy density E and the irradiation time, as measured by the number of pulses n. PF was only observed to occur for E\geq E_{m}, where E_{m} denotes the h-dependent threshold energy required to melt the film. Even at such small length scales, theoretical predictions for E_{m} obtained from a continuum-level lumped parameter heat transfer model for the film temperature, coupled with the 1-D transient heat equation for the substrate phase, were consistent with experimental observations provided that the thickness dependence of the reflectivity of the metal-substrate bilayer was incorporated into the analysis. The spacing between the nanoparticles and the particle diameter were found to increase as h^{2} and h^{5/3} respectively, which is consistent with the predictions of the thin film hydrodynamic (TFH) dewetting theory. These results suggest that fast thermal processing can lead to novel pattern formation, including quenching of a wide range of length scales and morphologies.Comment: 36 pages, 11 figures, 1 tabl