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271.
CHANG Min PENG Dan XU Ke-xin 《光电子快报》2007,3(3):211-214
A double beam near-infrared spectrometer is developed to compensate the water absorption and instrumental drift in intensity. The spectrometer may be used for both single and double beam measurements,and the two operation modes are compared. The results show that the double beam technique eliminates instrumental drift in the single beam measurement and therefore the stability of the system increases by more than 20%. The compensation of the double beam system on water absorption is verified by the measurement of fat content in milk. The results show that the spectrum data based on double beam mode get better calibration model and lower prediction error than traditional single beam mode. 相似文献
272.
Using the Embedding Atom Method (EAM) for highly undercooled Ni3Al alloy, the melting point and the specific heat were studied by a molecular dynamics simulation. The simulation of melting
point was carried out by means of the sandwich method and the NVE ensemble method, and the results show a good agreement,
whereas are larger than the experimental value of 1663 K. This difference is attributed to the influence of surface melting
on experimental results, which causes the smaller measurements compared with the thermodynamic melting point. The simulated
specific heat of Ni3Al alloy weakly and linearly increases with the increase of undercooling in the temperature range from 800 K to 2000 K.
Supported by the National Natural Science Foundation of China (Grant No. 50395101) 相似文献
273.
For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we propose using a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge. With two-dimensional (2D) particle-in-cell (PIC) simulations, we show that, in spite of Coulomb forces, all of the electrons in the laser spot can be accelerated synchronously, and the REM keeps its surface charge density during evolution. We also developed a self-consistent 1D theory, which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory allows us to predict the REM parameters and shows a good agreement with the 2D PIC simulations. 相似文献
274.
Within the framework of the effective-mass approximation, the exciton states and interband optical transitions in InxGa1−xN/GaN strained quantum dot (QD) nanowire heterostructures are investigated using a variational method, in which the important built-in electric field (BEF) effects, dielectric-constant mismatch and three-dimensional confinement of the electron and hole in InxGa1−xN QDs are considered. We find that the strong BEF gives rise to an obvious reduction of the effective band gap of QDs and leads to a remarkable electron-hole spatial separation. The BEF, QD height and radius, and dielectric mismatch effects have a significant influence on exciton binding energy, electron interband optical transitions, and the exciton oscillator strength. 相似文献
275.
采用基于密度泛函的第一性原理方法研究了(Si3-xCux)N4(x=0,0.25,0.5,0.75,1)晶体的稳定性、力学性能和电子结构,分析了Cu掺杂对β-Si3N4力学性能的影响机制.结果表明,(Si3-xCux)N4为热力学稳定结构,Cu掺杂降低了β-Si3N4的稳定性.由弹性常数和Voigt-Reuss-Hill近似看出,(Si3-xCux)N4满足波恩力学稳定性判据,Cu掺杂使得β-Si3N4的体模量、剪切模量和杨氏模量降低,当x=0时,(Si3-xCux)N4的体模量、剪切模量和杨氏模量最大,分别为234.3 GPa、126.7 GPa和322.1 GPa.根据泊松比和G/B值判断出(... 相似文献
276.
Won Keun Min 《Acta Mathematica Hungarica》2010,129(4):350-356
We introduce the notion of (δ,δ′)-continuous functions on generalized topological spaces and investigate characterizations for such functions. We study the
relationship between (δ,δ′)-continuity and several types of continuity on generalized topological spaces. 相似文献
277.
本文用Liapunov第二方法分析非保守力作用下直杆的塑性动态稳定性.杆处于粘性阻尼介质中,并受到切向均布的随动载荷作用.分析中在应力-应变关系中引入了应变率效应.导出了一个稳定性条件,并求出了临界失稳载荷,讨论了应变率效应对杆的稳定性的影响. 相似文献
278.
本文考虑的是备货型商品的生产与优化管理。商品的生产过程是随机可控的。需求过程是一个根据销售价格高低来控制的随机过程。本文主要研究是这样一个系统的利润函数。 相似文献
279.
A popular approach to solving the complementarity problem is to reformulate it as an equivalent equation system via a complementarity
function. In this paper, we propose a new class of functions, which contains the penalized natural residual function and the
penalized Fischer–Burmeister function for symmetric cone complementarity problems. We show that this class of functions is
indeed a class of complementarity functions. We finally prove that the merit function of this new class of complementarity
functions is coercive. 相似文献
280.
The objective of this study is to generate an optimal surgery schedule of elective surgery patients with uncertain surgery operations, which includes uncertainty in surgery durations and the availability of downstream resources such as surgical intensive care unit (SICU) over multi-periods. The stochastic optimization is adapted and the sample average approximation (SAA) method is proposed for obtaining an optimal surgery schedule with respect to minimizing the total cost of patient costs and overtime costs. A computational experiment is presented to evaluate the performance of the proposed method. 相似文献