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21.
Sanjay B. Bansode Ramesh S. Kapadnis Abu S. Ansari Vasant G. Wagh Anil N. Kulkarni Sampat S. Kale Habib M. Pathan 《Journal of Materials Science: Materials in Electronics》2016,27(12):12351-12356
Films of indium selenide was deposited onto glass and indium tin oxide coated glass substrates in acidic medium using chemical bath deposition at room temperature. Indium sulphate and sodium selenosulphate were used as precursors of In3+ and Se2?, respectively. The structural, surface morphological and optical properties of the deposited films were studied. Diffractograms in structural study revealed the deposited material is In2Se3 films. Controlled bath conditions resulted in the evolution of the In2Se3 microrod-like morphology. The optical band gap of the film was found to be 1.7 eV. 相似文献
22.
Common-input models for multiple neural spike-train data 总被引:2,自引:0,他引:2
Recent developments in multi-electrode recordings enable the simultaneous measurement of the spiking activity of many neurons. Analysis of such multineuronal data is one of the key challenge in computational neuroscience today. In this work, we develop a multivariate point-process model in which the observed activity of a network of neurons depends on three terms: (1) the experimentally-controlled stimulus; (2) the spiking history of the observed neurons; and (3) a hidden term that corresponds, for example, to common input from an unobserved population of neurons that is presynaptic to two or more cells in the observed population. We consider two models for the network firing-rates, one of which is computationally and analytically tractable but can lead to unrealistically high firing-rates, while the other with reasonable firing-rates imposes a greater computational burden. We develop an expectation-maximization algorithm for fitting the parameters of both the models. For the analytically tractable model the expectation step is based on a continuous-time implementation of the extended Kalman smoother, and the maximization step involves two concave maximization problems which may be solved in parallel. The other model that we consider necessitates the use of Monte Carlo methods for the expectation as well as maximization step. We discuss the trade-off involved in choosing between the two models and the associated methods. The techniques developed allow us to solve a variety of inference problems in a straightforward, computationally efficient fashion; for example, we may use the model to predict network activity given an arbitrary stimulus, infer a neuron's ring rate given the stimulus and the activity of the other observed neurons, and perform optimal stimulus decoding and prediction. We present several detailed simulation studies which explore the strengths and limitations of our approach. 相似文献
23.
Samples of the copper-cadmium ferrite series Cd
x
Cu1–x
Fe2O4 (x=0 to 1) have been investigated by means of Mössbauer spectroscopy at 77 K. Mössbauer spectra forx=0.0 to 0.7 suggest the existence of two hyperfine fields, one due to the Fe3+ tetrahedral ions (A-sites) and the other due to the Fe3+ octahedral ions (B-sites), while forx=0.8 it shows relaxation behaviour and forx0.9 it exhibits a paramagnetic quadrupole doublet. The systematic dependence of the isomer shifts, line widths, quadrupole interactions and nuclear magnetic fields of57Fe3+ ions in both A and B sites has been determined as a function of cadmium content. The variation of nuclear magnetic fields at the A and B sites is explained on the basis of the A-B and B-B supertransferred hyperfine interactions. Analysis of the average Mössbauer line widths as a function of cadmium concentration suggests that the relaxation spectrum observed atx=0.8 (77 K) is possibly due to domain wall oscillations. It has been found here that QS (B) increases from CuFe2O4to CdFe2O4 as the cadmium concentration is increased. 相似文献
24.
Proactive thermal management in green datacenters 总被引:1,自引:1,他引:0
Eun Kyung Lee Indraneel Kulkarni Dario Pompili Manish Parashar 《The Journal of supercomputing》2012,60(2):165-195
The increasing demand for faster computing and high storage capacity has resulted in an increase in energy consumption and
heat generation in datacenters. Because of the increase in heat generation, cooling requirements have become a critical concern,
both in terms of growing operating costs as well as their environmental and societal impacts. Presently, thermal management
techniques make an effort to thermally profile and control datacenters’ cooling equipment to increase their efficiency. In
conventional thermal management techniques, cooling systems are triggered by the temperature crossing predefined thresholds.
Such reactive approaches result in delayed response as the temperature may already be too high, which can result in performance
degradation of hardware. 相似文献
25.
T. K. Vishnuvardhan V. R. Kulkarni C. Basavaraja S. C. Raghavendra 《Bulletin of Materials Science》2006,29(1):77-83
Conducting polymer composites of polypyrrole/yttrium oxide (PPy/Y2O3) were synthesized byin situ polymerization of pyrrole with Y2O3 using FeCl3 as an oxidant. The Y2O3 is varied in five different weight percentages of PPy in PPy/Y2O3 composites. The synthesized polymer composites are characterized by infrared and X-ray diffraction techniques. The surface
morphology of the composite is studied by scanning electron microscopy. The glass transition temperature of the polymer and
its composite is discussed by DSC. Electrical conductivity of the compressed pellets depends on the concentration of Y2O3 in PPy. The frequency dependent a.c. conductivity reveals that the Y2O3 concentration in PPy is responsible for the variation of conductivity of the composites. Frequency dependent dielectric constant
at room temperature for different composites are due to interfacial space charge (Maxwell Wagner) polarization leading to
the large value of dielectric constant. Frequency dependent dielectric loss, as well as variation of dielectric loss as a
function of mass percentage of Y2O3 is also presented and discussed. 相似文献
26.
Total radiation dose at geostationary orbit 总被引:1,自引:0,他引:1
Active semiconductor components in satellites are sensitive to accumulated ionization radiation dose. Radiation dose and shielding estimations for electronic components are usually carried out using NASA models of space radiation particle flux. Accurate measurement of accumulated dose during the life of a satellite is essential for optimizing radiation shielding design for electronic components. Dosimeters were designed using radiation sensitive field-effect transistors (RADFETs) and accumulated dose at geostationary orbit was measured. Radiation dose as measured by these dosimeters with spherical aluminum shields are presented and compared with NASA model doses. 相似文献
27.
A comparative dielectric relaxation study of PMN–PT and PMN–PZ ceramics using impedance spectroscopy
Surya M. Gupta Pragya Pandit Pankaj Patro Ajit R. Kulkarni Vinod K. Wadhawan 《Materials Science and Engineering: B》2005,120(1-3):194-198
AC-impedance spectroscopic studies in the temperature range of 30–400 °C are carried out on solid solutions of lead magnesium niobate (PMN) with lead titanate (PT) and lead zirconate (PZ), both of them in the 65/35 atomic ratio. For PMN–PT this corresponds to the morphotropic phase boundary composition (with normal ferroelectric behaviour), and for PMN–PZ it is near the phase boundary between normal ferroelectric and relaxor ferroelectric compositions. The variation of dielectric permittivity with temperature at different frequencies shows normal ferroelectric and relaxor-like dependence for PMN–PT and PMN–PZ, respectively. Temperature-dependent spectroscopic modulus plots reveal a much broader peak for PMN–PZ compared to that for PMN–PT, which is consistent with the dielectric behaviour. PMN–PT shows nearly ideal Debye behaviour below Tm (the temperature of the permittivity maximum) and the behaviour departs from ideality above Tm, whereas non-ideal Debye behaviour is seen both below and above Tm for PMN–PZ. Complex modulus plots fit well with two depressed semicircles and three depressed semicircles, respectively, for PMN–PT and PMN–PZ. The relaxation observed in the spectroscopic plots around 1 MHz for PMN–PT has been assigned to polarisation relaxation expected for normal-sized domains. No such relaxation could be observed for PMN–PZ around 1 MHz because of the mesoscopic domain sizes. 相似文献
28.
S. Di Gennaro C. Horn S. R. Kulkarni P. J. Ramadge 《Discrete Event Dynamic Systems》1998,8(4):343-351
We consider a class of hybrid dynamical systems and obtain conditions under which the behavior of these systems can be reduced to a finite state automaton. Specifically, we consider timed automata with more general enabling regions coupling the continuous and discrete dynamics than those previously considered. We provide a necessary condition for the existence of a finite state reduction, together with examples showing that this condition is not sufficient. We then give two sufficient conditions that provide a large class of systems with general enabling regions which admit finite reductions. 相似文献
29.
Cao Dongyang Malakooti Sadeq Kulkarni Vijay N. Ren Yao Lu Hongbing 《Mechanics of Time-Dependent Materials》2021,25(3):353-363
Mechanics of Time-Dependent Materials - Debonding at the core–skin interphase region is one of the primary failure modes in core sandwich composites under shear loads. As a result, the... 相似文献
30.
In the present work, the nanocomposites based on different transition metal oxides like iron oxide (Fe2O3), zinc oxide (ZnO), silicon dioxide (SiO2), zirconium dioxide (ZrO2), and titanium dioxide (TiO2) in PVA matrix have been studied for their suitability as electromagnetic interference (EMI) shielding materials in the frequency range of 4–8 GHz (C-band) and 8–12 GHz (X-band). The nanocomposites containing 0.1, 0.5, 1.0, 5.0, and 10.0 wt% of oxides in the matrix were synthesised by solvent casting method. The EMI attenuation studies in 4–12 GHz frequency range were carried out using the Vector Network Analyzer R & S: ZVA40 method by measuring the loss due to reflection. The minimum reflectivity values for the composites containing Fe2O3, ZnO, SiO2, ZrO2, and TiO2 in PVA matrix at 10 wt% concentration level in the matrix were found to be ?38.85 dB (10.4 GHz), ?33.65 dB (10.4 GHz), ?41.90 dB (10.4 GHz), ?24.90 dB (11.0 GHz), and ?32.90 dB (9.76 GHz), respectively. Based on these results, the SiO2- and Fe2O3-based composites, which also exhibit high thermal stability and mechanical strength, are found to be low-cost and efficient EMI shielding materials. 相似文献