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排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
Gabor Schmera Adi Bulsara David Pierson Frank Moss Enrico Di Cera 《Journal of statistical physics》1993,71(5-6):1179-1190
We consider the class of experiments which can be characterized by a Fokker-PIanck dynamics corresponding to the overdamped motion of a state point in a suitable stochastic potential. We assume that the general form of the potential is known (or can be guessed with reasonable accuracy), but that its parameters are to be determined experimentally by measurements made with a noisy instrument. This possible method for determining the potential parameters, which exploits the system's own internal stochastic motion in order to explore rapidly its available parameter space, is substantially more efficient than traditional methods involving time averages of single point measurements, and yet does not appear to have been previously considered. The method could be important when, for example, the experiment must be completed in a limited time owing either to the expense of the experimental materials or to the temporary stationarity of the preparation, situations which are commonly encountered in experimental biochemistry and biology. 相似文献
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Three augmented penalty function algorithms are tested and compared with an ordinary penalty function algorithm for two demonstration optimal control problems. Although the augmented penalty function is quite helpful in solving control problems with terminal state constraints, the convergence can be improved significantly by providing systematic increases in the penalty constant. 相似文献
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M. J. Jackson C. Gilligan A. V. Davies R. Britton J. I. Friese L. R. Greenwood B. D. Pierson Z. S. Finch B. N. Gartman D. Dry I. May N. C. Smythe A. J. Gaunt E. R. Thomas K. E. Roberts N. K. Harward K. J. Thomas P. T. Woody P. Zhao 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(1):107-115
Samarium-153 (\({}^{153}\hbox {Sm}\)) is a short-lived radionuclide that decays to stable europium-153 via beta emission, with subsequent de-excitation via gamma emission and internal conversion. Historical measurements of \({}^{153}\hbox {Sm}\) by gamma spectrometry and beta liquid scintillation counting have shown a low bias compared to beta proportional counting. In order to investigate this, four national laboratories jointly conducted an experimental inter-comparison exercise on a certified \({}^{153}\hbox {Sm}\) sample, created from neutron activation of samarium-152. Radiometric measurements were conducted using gamma spectrometry, liquid scintillation counting, gas proportional counting, and passivated implanted planar silicon detectors and compared across the four institutions against the certified value. The results from this experiment are presented together with a number of conclusions which suggest that the current published cumulative fission yield for \({}^{153}\hbox {Sm}\), as used by many laboratories, is approximately 15% high and is the likely cause of the previously observed bias. 相似文献
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M. Hari Prasad Reddy J. F. Pierson S. Uthanna 《Crystal Research and Technology》2011,46(12):1329-1336
Thin films of Ag2Cu2O3 were formed on glass substrates by RF magnetron sputtering technique under different oxygen partial pressures in the range 5 × 10‐3 – 8 × 10‐2 Pa using mosaic target of Ag70Cu30. The influence of oxygen partial pressure on the core level binding energies, crystallographic structure, and electrical and optical properties of the deposited films was studied. The atomic ratio of copper to silver in the films was 0.302. The oxygen content was in correlation with the oxygen partial pressure maintained during the growth of the films. The films formed at oxygen partial pressures < 2 × 10‐2 Pa was mixed phase of Ag2Cu2O3 and Ag. The films deposited at 2 × 10‐2 Pa were single phase of Ag2Cu2O3. The crystallite size of the films formed at 2 × 10‐2 Pa was 12 nm, while those films annealed at 473 K was 16 nm. The nanocrystalline Ag2Cu2O3 films formed at oxygen partial pressure of 2 × 10‐2 Pa showed electrical resistivity of 8.2 Ωcm and optical band gap of 1.95 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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P. Narayana Reddy A. Sreedhar M. Hari Prasad Reddy S. Uthanna J. F. Pierson 《Crystal Research and Technology》2011,46(9):961-966
Nano‐crystalline silver oxide films were deposited on glass and silicon substrates held at room temperature by RF magnetron sputtering of silver target under different oxygen partial pressures. The influence of oxygen partial pressure on the structural, morphological, electrical and optical properties of deposited films was investigated. Varying oxygen partial pressure during the sputter deposition leads to changes of mixed phase of Ag2O and Ag to a single phase of Ag2O and to AgO. The X‐ray diffraction and X‐ray photoelectron spectroscopy results showed the formation of single phase Ag2O with cubic structure at oxygen partial pressures of 2x10‐2 Pa while the films deposited at higher oxygen partial pressure of 9x10‐2 Pa showed the formation of single phase of AgO with monoclinic structure. Raman spectroscopic studies on the single phase Ag2O showed the stretching vibration of Ag‐O bonds. Single‐phase Ag2O films obtained at oxygen partial pressure of 2x10‐2 Pa were nano‐crystalline with crystallite size of 20 nm and possessed an electrical resistivity of 5.2x10‐3 Ωcm and optical band gap of 2.05 eV. The films deposited at higher oxygen partial pressure of 9x10‐2 Pa were of AgO with electrical resistivity of 1.8x10‐2 Ωcm and optical band gap of 2.13 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Adrian Huang Kellie Wo Allene Pierson So Yeun Christine Lee Erin Yang Catherine Johnson 《Journal of heterocyclic chemistry》2016,53(5):1499-1504
The novel and one‐pot synthesis of 5‐hydroxyl hydantoins from Ugi five‐component condensation procedures is reported. The transformation was promoted via a microwave heating method and provided 5‐hydroxyl hydantoins in workable yields, representing a direct approach to this synthetically challenging and biologically interesting pharmacophore. 相似文献