带有负顾客且具有反馈的M/G/1排队模型

将负顾客和反馈相结合研究了一类带有负顾客且具有反馈的M／G／1排队系统，正顾客服务完会以一定的概率立刻排到队尾等待下一次服务，以一定的概率离开系统，永不再来。这里考虑了负顾客的两种抵消情况，分别是负顾客抵消队列中的最后一个正顾客和负顾客抵消队首的正顾客，并分别给出了它们稳态存在的充分必要条件，利用补充变量法和状态转移分析模型，得到了它们的稳态队长的概率母函数。     

Stream flow forecasting using neuro‐wavelet technique

This paper proposes the application of a neuro‐wavelet technique for modelling monthly stream flows. The neuro‐wavelet model is improved by combining two methods, discrete wavelet transform and multi‐layer perceptron, for one‐month‐ahead stream flow forecasting and results are compared with those of the single multi‐layer perceptron (MLP), multi‐linear regression (MLR) and auto‐regressive (AR) models. Monthly flow data from two stations, Gerdelli Station on Canakdere River and Isakoy Station on Goksudere River, in the Eastern Black Sea region of Turkey are used in the study. The comparison results revealed that the suggested model could increase the forecast accuracy and perform better than the MLP, MLR and AR models. Copyright © 2008 John Wiley & Sons, Ltd.     

The continuous limit of the multiple lens effect and the optical scalar equation

We study the continuous limit of the multiple gravitational lensing theory based on the thin lens approximation. We define a new, light-path dependent angular diameter distance     and show that it satisfies the optical scalar equation. The distance provides relations between quantities used in gravitational lensing theory (the convergence, the shear and the twist terms) and those used in scalar optics theory (the rates of expansion, shear and rotation).     

Post-Common-Envelope Binaries with Distorted Secondaries

We will examine the properties of binary systems which have Roche lobe filling secondaries and white dwarf primaries as well as systems where the secondary is only partially filling its Roche lobe. We will also discuss observational properties such as ellipsoidal variations, light reprocessing and radial velocity measurements of the close binary systems BPM 71214, EC 13471-1258 and GD 245. The properties of BPM 71214 and EC 13471-1258 show that these systems may be pre-cataclysmic variables just prior to the onset of mass transfer or they may be hibernating novae. GD 245 is a pre-cataclysmic variable.     

南海海域4种笛鲷的微卫星DNA分析

摘要：采用聚丙烯酰胺凝胶电泳技术，从20对西大西洋笛鲷（Lutjanus campechamus）的微卫星引物中筛选适用于红鳍笛鲷（L．erythopterus）、勒氏笛鲷（L.russellii）、紫红笛鲷（L.argentimaculatus）和约氏笛鲷（L.johnii）基因组分析的微卫星引物，分析4种笛鲷的遗传多样性及系统发生。经反应条件的优化，从20对引物中筛选出17对可稳定扩增出特异片段的引物。通过测序证实扩增产物含微卫星位点后，以该17对引物对4个种的群体进行遗传多样性分析。其中16对可在约氏笛鲷、勒氏笛鲷、紫红笛鲷基因组中扩增出重复性好的特异性条带，分别有65％、65％、60％呈现出种内多态：15对可在红鳍笛鲷中扩增出重复性好的特异性条带，并且全部呈现出种内多态。四种笛鲷中，红鳍笛鲷的多态性最高，高度多态基因座占检测座位的66．67％；勒氏笛鲷的多态性最低，低度多态基因座占43．75％。获得3个种间特异性分子标记。用风和DA两种方法计算4种笛鲷的遗传距离，构建了系统发生树。     

Analytical model for fully three‐dimensional radial dispersion in a finite‐thickness aquifer

Analytical solutions for contaminant transport in a non‐uniform flow filed are very difficult and relatively rare in subsurface hydrology. The difficulty is because of the fact that velocity vector in the non‐uniform flow field is space‐dependent rather than constant. In this study, an analytical model is presented for describing the three‐dimensional contaminant transport from an area source in a radial flow field which is a simplest case of the non‐uniform flow. The development of the analytical model is achieved by coupling the power series technique, the Laplace transform and the two finite Fourier cosine transform. The developed analytical model is examined by comparing with the Laplace transform finite difference (LTFD) solution. Excellent agreements between the developed analytical model and the numerical model certificate the accuracy of the developed model. The developed model can evaluate solution for Peclet number up to 100. Moreover, the mathematical behaviours of the developed solution are also studied. More specifically, a hypothetical convergent flow tracer test is considered as an illustrative example to demonstrate the three‐dimensional concentration distribution in a radial flow field. The developed model can serve as benchmark to check the more comprehensive three‐dimensional numerical solutions describing non‐uniform flow contaminant transport. Copyright © 2009 John Wiley & Sons, Ltd.     

Consolidation analysis of saturated multi‐layered soils with anisotropic permeability caused by a point sink

This paper presents the analytical layer‐element method to analyze the consolidation of saturated multi‐layered soils caused by a point sink by considering the anisotropy of permeability. Starting from the governing equations of the problem, the solutions of displacements and stresses for a single soil layer are obtained in the Laplace–Hankel transformed domain. Then, the analytical layer‐element method is utilized to further derive the solutions for the saturated multi‐layered soils in the transformed domain by combining with the boundary conditions of the soil system and continuity conditions between adjacent layers. The actual solutions in the physical domain can be acquired by the inversion of Laplace–Hankel transform. Numerical results are carried out to show the accuracy and stability of the proposed method and evaluate the influence of sink depth and anisotropic permeability on excess pore pressure and surface settlement. Copyright © 2011 John Wiley & Sons, Ltd.     

基于相似性原理超固结土不排水扩张半解析解

在实际工程中,土体往往因卸载、再加载等复杂应力路径而处于超固结状态,而现有的圆孔扩张问题的计算模型往往不能反映超固结土中剪胀、软化等一些特殊性质。为了解决这一问题,基于相似性原理和统一硬化（UH）模型,结合相关联的流动法则和大变形理论,采用相似求解技术求解了超固结土不排水扩张问题的半解析解答。通过理想化算例分析了圆孔扩张挤土产生的应力和孔压响应,并通过分析不同超固结比OCR的土体应力路径的变化规律,讨论了UH模型的适用性。结果表明：对于轻超固结土,空腔周围土体孔压在塑性区沿径向单调递减,随着OCR增大,塑性区内孔压分布呈现出“S”形的趋势,孔壁附近的孔压逐渐减小,孔壁周围甚至出现负孔压。随着OCR增大,压力?扩张曲线收敛变慢。在扩孔过程中正常固结土一直处于剪缩硬化阶段。而对于超固结土,土体则经历了临界状态→剪胀硬化阶段→临界（特征）状态→剪缩硬化阶段。该研究成果不仅丰富了相似求解技术的应用,而且为超固结土中桩基承载力、隧道围岩变形预测和原位测试参数等岩土工程问题的计算提供了理论依据。     

三种插值方法在降水等值线绘制中的对比分析

为对比不同插值方法在宁夏回族自治区的适用性,基于宁夏及其周边地区77个气象台站1956—2016年平均降水量数据,运用泰森多边形法、距离平均反比法、克里金插值法对降雨量数据进行空间插值和交叉验证,从插值方法的稳健性和准确度出发进行对比分析,得出适用于宁夏回族自治区的插值方法。研究表明：（1）从准确度来看,克里金插值法与观测值走向、位置较为相似;从稳健性来看,克里金插值法MAE平均值为4.43 mm、RMSE平均值为10.36 mm,显著小于泰森多边形法和距离平均反比法。（2）整体来看,克里金插值法更为理想,可以用于宁夏回族自治区降水量空间插值分析。     

一种基于快速傅里叶变换的多普勒天气雷达弱杂波识别方法

多普勒天气雷达探测时常会出现电磁干扰和超折射等杂波干扰问题,通过对弱径向干扰回波的规律性特征分析,提出了一种基于快速傅里叶变换的多普勒天气雷达干扰回波识别算法,并成功应用于多普勒天气雷达径向干扰回波的识别中。研究表明,一些干扰回波具有明显的空间周期性规律,对反射率因子进行快速傅里叶变换,得到的频域上能量分布具有与常规回波明显的差异。依靠这些差异可以较好地对一些弱的干扰回波进行识别并剔除。该方法对径向上离散分布的干扰回波均有较好的识别能力,但对相对均匀和密实的径向干扰回波识别能力较弱。