无穷多目标优化的Geoffrion真有效性及其在鲁棒优化中的应用

在多目标优化中,Pareto有效性体现了目标之间的妥协与补偿,而Geoffrion真有效性能保证补偿是有界的.本文对有无穷多个目标的优化问题引入了真有效性,完整保留了Geoffrion的结构.基于一族锥,揭示了Geoffrion真有效性的特点及其与Pareto有效性的区别.并将Geoffrion真有效性的思想用于鲁棒优化,得到了著名的Hurwicz决策准则.     

Influence ofΛ Hyperons 1S0 Superfluidity on the Direct Urca Processes with Hyperons

In the framework of the relativistic mean field theory (RMFT), the relativistic energy losses of the direct Urca processes withhyperons (Y-DURCA) for reactionsΛ→p + e +\bar{\nu}_{e} andΞ^- →Λ + e +ν_e arestudied in neutron stars. We calculate the energy gap ofΛ hyperons and investigate the effects of the ¹S₀superfluidity (SF) ofΛ hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data\Delta B_ΛΛ∽1.01±0.20^+0.18_-0.11 MeV.The results indicate that the ¹S₀ SF ofΛ hyperons exists in most density ranges of happening the two reactions. The
theoretical cooling curves are in agreement with observation data.     

Piezoelectricity of ordered (ScxGa1-xN) alloys from first principles

First-principles calculations are performed to compute the e₃₃ piezoelectric coefficients of GaN, ScN and (Sc_xGa_1-xN) alloys exhibiting an alternation of hexagonal GaN, with hexagonal ScN along the c-axis. For Sc compositions larger than 50%, each atom has nearly five nearest neighbors (i.e., the ground state exhibits a phase that is five-fold coordinated). On the other hand, Sc-deficient (Sc, Ga) N alloys adopt a ground-state that is four-fold coordinated). The magnitude of e₃₃ in the Sc-deficient ideally ordered (Sc_0.25Ga_0.75N) is found to be larger than the magnitude of the corresponding e₃₃ coefficients resulting from the compositional weighted average over the hexagonal (h-ScN) and the wurtzite (w-GaN) parent compounds. On the other hand, the e₃₃ coefficients of the Sc-rich ordered (Sc_0.75Ga_0.25N) is found to be negligibly small. In addition, e₃₃ piezoelectric coefficients in ordered (Sc_0.5Ga_0.5N) exhibit quite large magnitudes, due to the nonpolar to polar transition occurs at Sc composition x = 0.5, and thus can bridge the corresponding coefficients of (Ga, In) N and ferroelectric alloys. The microscopic origins for this huge enhancement in the piezoelectric behavior in Sc-low and Sc-intermediate alloys and the role of each atom are revealed and discussed.     

水波聚焦的研究

利用水波槽装置观察到了水波聚焦现象,并利用流体力学中的表面波理论,借用光学中对折射率的定义,推出了与光线通过薄透镜聚焦完全对应的水波聚焦理论公式,以及焦距随水深变化的关系曲线,从而将水波的几何特性与光波的几何特性统一起来。     

水平梯度表面能材料表面上的滴状凝结换热系数

本文在均质表面的单个球缺形液滴换热模型和液滴通用尺度分布规律的基础上,结合梯度表面能材料表面的液滴分布和凝结换热特性,得到了一维水平梯度表面能材料表面上的滴状凝结换热计算式。在此基础上,研究了壁面过冷度、接触角梯度、工质物性等参数对梯度表面能材料表面滴状凝结换热性能的影响。结果表明:随着过冷度的增加和凝结工质汽化潜热的增大和表面张力的减小和接触角梯度的增大,平均表面凝结换热系数会增大。     

Gauge-invariant treatment of the exponential decay of an unstable atomic state

Summary By using a self-consistent projection-operator method, developed recently by the present author, a gauge-invariant Markovian treatment of the spontaneous decay of an unstable atomic state is presented. Without ignoring retardation and electron-spin effects a gauge-invariant result for the probability amplitude of finding the atom in the unstable state is obtained.     

X-ray fluorescence intensity distribution in circular specimens

Summary The relative X-ray fluorescence (XRF) intensities for annular source and various annular specimen are measured with a Ge-Li detection system and calculated by the Monte Carlo numerical techniques (MCNT).Kα X-ray intensities of annular specimens with different radii prepared from a pure-molybdenum foil are measured and it is seen that the measured values are in good agreement with the values calculated by MCNT. The variation of the fluorescence intensity due to the collimator radius is also studied. The differences between the MCNT and experimental results are discussed in terms of the possible sources of errors.     

Axiomatic Geometric Formulation of Electromagnetism with Only One Axiom: The Field Equation for the Bivector Field <Emphasis Type="Italic">F</Emphasis> with an Explanation of the Trouton-Noble Experiment

In this paper we present an axiomatic, geometric, formulation of electromagnetism with only one axiom: the field equation for the Faraday bivector field F. This formulation with F field is a self-contained, complete and consistent formulation that dispenses with either electric and magnetic fields or the electromagnetic potentials. All physical quantities are defined without reference frames, the absolute quantities, i.e., they are geometric four-dimensional (4D) quantities or, when some basis is introduced, every quantity is represented as a 4D coordinate-based geometric quantity comprising both components and a basis. The new observer-independent expressions for the stress-energy vector T(n) (1-vector), the energy density U (scalar), the Poynting vector S and the momentum density g (1-vectors), the angular momentum density M (bivector) and the Lorentz force K ((1-vector) are directly derived from the field equation for F. The local conservation laws are also directly derived from that field equation. The 1-vector Lagrangian with the F field as a 4D absolute quantity is presented; the interaction term is written in terms of F and not, as usual, in terms of A. It is shown that this geometric formulation is in a full agreement with the Trouton-Noble experiment.     

垂直入射时无限长分层柱电磁散射的改进算法及应用

结合非均匀球粒子对平面波散射的散射场计算的改进算法,提出了平面波垂直入射无限长分层圆柱散射场快速稳定而有效的改进电磁散射算法。与已有算法相比,改进算法所能计算的无限长非均匀介质圆柱的尺寸参量突破10000,计算层数达到106,并且计算时间很短,最多仅为几秒。该算法可以用于不同的波段以及不同领域的任意无耗或吸收无限长圆柱体散射场的计算。最后将该算法应用于梯度折射率聚合物光纤(GI-POF)散射特性的研究,为非接触、在线测量聚合物光纤折射率分布提供了理论依据。     

A novel frame shift and integral technique for processing low-light-level moving image sequence

A new method for processing low-light-level moving image sequence is proposed, in which (1) a novel algorithm based on difference processing has been firstly developed to determine the motion parameters of moving image sequence, (2) the spatial relativity of the frames within moving image sequence can be then well established after frame shifting according to motion parameters obtained above, (3) finally, frame integration method can be applied to each processed frame, thereby increasing the signal-to-noise ratio of low-light-level moving image sequence. Experiments have been carried out to verify the validity of the proposed method, which show that the parameters obtained by the developed algorithm coincide well with the actual values, and the SNRs of the moving image sequences were effectively increased with the proposed method, indicating that the method offers significant advantages in the enhancement of low-light-level moving image sequence.