Speed sensorless field oriented control of ac induction motor using model reference adaptive system

In order implement the vector control technique, the motor speed information is required. Incremental encoder, resolvers and tachogenerator, are used to reveal the speed. These sensors require careful mounting and alignment and special attention is required with electrical noises. Sensorless speed vector control is greatly used and applied in induction machine drives instead of scalar control and vector control for their robustness and reliability, and very low maintenance cost. In this project MRAS based techniques are used to estimate the rotor speed based on rotor flux estimation, the estimated speed in the MRAS algorithm is used as a feedback for the vector control system. The model reference adaptive control system is predicated on the comparison between the outputs of adjustable model and reference model. The error between them is employed to drive a suitable adaptation mechanism which generates the estimated rotor speed for the adjustable model. And indirect vector control scheme controls the flux and torque by restricting the torque and flux errors with respective hysteresis bands, and motor flux and torque are controlled by the stator voltage space vectors using optimum inverter switching table. Modeling and simulation of the induction machine and the vector control drives implemented in MATLAB/SIMULINK. Simulation results of proposed MRAS and indirect vector control technique are presented

Neutrino and anti-neutrino energy loss rates due to iron isotopes suitable for core-collapse simulations

Accurate estimate of neutrino energy loss rates are needed for the study of the late stages of the stellar evolution, in particular for cooling of neutron stars and white dwarfs. The energy spectra of neutrinos and antineutrinos arriving at the Earth can also provide useful information on the primary neutrino fluxes as well as neutrino mixing scenario (it is to be noted that these supernova neutrinos are emitted after the supernova explosion which is a much later stage of stellar evolution than that considered in this paper). Recently an improved microscopic calculation of weak-interaction mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. Here I present for the first time the fine-grid calculation of the neutrino and anti-neutrino energy loss rates due to $^{54,55,56}$Fe in stellar matter. In the core of massive stars isotopes of iron, $^{54,55,56}$Fe, are considered to be key players in decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture on these nuclide. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes. The calculated cooling rates are also compared with previous calculations.Comment: 12 pages, 3 figures and 1 table. arXiv admin note: text overlap with arXiv:1108.4569, arXiv:1203.4675, arXiv:1203.434

Cancer cell expulsion of anticancer drugs through shedding of microvesicles: association with drug resistance and tumour survival

Microvesicles (MVs) are small (0.1-≤1 µm in diameter) heterogeneous vesicles released from cells constitutively or upon activation, that mediate intercellular communication. Multi-drug resistance (MDR) has been defined as the ability of cancer cells to survive after treatment with various drugs. However, the mechanism(s) used by cancer cells to evade apoptosis induced by anticancer drugs remain unclear and was the subject of our investigation. Here we report a novel mechanism of cancer cell expulsion of anticancer drugs through the release of MVs, followed by the recruitment of lysosomes to the site of release to repair the resulting damage. In addition, we show for the first time that inhibition of MV release by pretreatment of PC3M cells with the calpain inhibitor, calpeptin, sensitizes cancer cells to drug-elicited apoptosis mediated by the addition of methotrexate (MTX) and docetoxel (DOC) using at least 10-fold lower concentrations, both in vitro and in vivo. Treatment of cancer patients with MET or DOC leads to significant side effects due to the use of higher doses. Here we show that these drugs when administered together with calpeptin can be given at doses 100 times lower and still induce effective killing of target cancer cells. Overall our studies shed light on the role of MV release in cancer cell expulsion of anticancer drugs and subsequent evasion and survival from apoptosis and suggest new combination therapies for existing cancer drugs.Peer reviewedFinal Accepted Versio