科技保险中项目投资损失保险投保比例优化决策

针对我国科技保险第二批推行险种--项目投资损失保险,以科技企业为研究主体,综合考虑其期望利润和科技风险(方差),构建了投保比例模型.在对武汉市迪源光电科技有限公司投保科技保险的具体案例中,运用线性不等式组的旋转算法进行求解,计算出企业在项目组合投资中如何优化各项投保比例,使其以最小的风险承担得到最大的期望利润.     

多周期多目标条件风险值模型

在商业、工业、电力和房地产等行业中存在许多复杂的多周期风险决策问题,它的数学模型研究对于解决这些问题具有重要的作用.作者建立了一种新的多周期多目标条件风险值(CVaR)数学模型理论和方法.先定义了一种带时间段的多周期多目标损失函数下的α-VaR和α-CVaR值,给出了一类多周期多目标CVaR最优化模型.然后,证明了多目标意义下的对应模型的等价定理,给出了多周期多目标CVaR模型的近似求解等价模型.最后,建立了一种生产企业在供过于求和供不应求两种情形下产生的多周期双目标CVaR模型,针对一个电力生产企业进行的数值实验,表明了模型可以得到在最小供给的用电损失分布下的各周期下的相匹配供电策略,可以帮助供电部门各个时期供电不平衡状况下的风险控制.     

Classification with Gaussians and convex loss Ⅱ:improving error bounds by noise conditions

We continue our study on classification learning algorithms generated by Tikhonov regularization schemes associated with Gaussian kernels and general convex loss functions. Our main purpose of this paper is to improve error bounds by presenting a new comparison theorem associated with general convex loss functions and Tsybakov noise conditions. Some concrete examples are provided to illustrate the improved learning rates which demonstrate the effect of various loss functions for learning algorithms. In our ...     

桁架拱结构在地震动双向多点激励下的反应分析

基于经验相干损失函数和《建筑抗震设计规范》定义的反应谱模拟了空间变化地震动,进行了空间变化水平向和竖向地震动共同激励下桁架拱结构的反应分析。数值分析结果表明,与一致激励引起的结构反应相比,考虑地震动的空间变化增大了桁架拱结构的地震反应,引起地震动空间变化的每一个因素对于结构反应都有重要的影响。传统的基于一致地震动和仅考...     

Thermal and dielectric studies of nickel malonate dihydrate single crystals

Single crystals of nickel malonate dihydrate were grown by the gel technique, employing the single diffusion method. Thermal dehydration of the crystal was investigated by thermogravimetric and differential thermal analyses. The title compound exhibits a steady thermal behaviour at higher temperature range of 350-800 °C. The dielectric properties of the prepared sample were analyzed as a function of frequency in the range of 1 kHz-1 MHz and at temperatures between 40 and 140 °C.     

Fabrication of fluorinated polyimide optical waveguides by micropen direct writing technology

A novel and cheap direct writing method based on the micropen has been developed to fabricate fluorinated polyimide stripe optical waveguides on Si/SiO₂ wafers. The overall design, starting material, micropen direct writing system and fabrication processes of the stripe optical waveguides are presented. The effects of the key direct writing parameters, such as the tip-to-substrate distance, extrusive gas pressure, writing speed and viscosity of the polyamic acid, on the dimension and morphology of the stripe optical waveguides are discussed in detail. After deposition by the micropen system and baking process, the fluorinated polyimide stripe optical waveguides with good morphology and surface quality can be fabricated using the optimal parameters. The propagation losses at the wavelength of 1.55 μm are in the range of 1.4-3.5 dB cm⁻¹ as characterized by different length combinations of the strip optical waveguides.     

内锥式流量计数值模拟及优化设计

多相流过程参数的准确测量在石油化工与冶金工业等工业过程中十分重要。内锥式流量计作为一种新型差压流量计在多相流测量中逐渐受到关注,它能在较短的直管段条件下对流体实现准确的测量,但其结构尚存在优化的空间,需进行深入研究。本文对传统内锥式流量计做结构变形和优化研究,利用计算流体力学(CFD)方法对DN50 mm水平管道中内锥变形体的流场进行数值模拟,分析在不同结构参数下锥体的水力特性以优化结构。数值仿真结果表明,综合内锥式流量计在取压点、永久压损及测量精确度等因素,优化后的结构可以显著降低永久压损,提高测量重复性和精确度。     

北半球环流系统季节内及年际以上振荡信号的信息传输

利用NCEP/NCAR月平均高度场再分析资料,分别提取季节内和年际以上振荡的基本特征和形式,运用信息传输理论分析这两种振荡信号的信息在低纬度与中高纬度间的传输.发现季节内振荡信号信息损失率较年际以上的偏大,且在特定地区这两种振荡信号的信息具有反向传输的特征;空间传输的水平分布上,两种振荡信号均表现为纬向上低纬度信息损失率大且海陆分布差异显著;空间传输的垂直分布上,年际以上振荡信号的低纬度高空信息损失率较大,中高纬度从对流层至平流层底信息损失率都较小,而季节内振荡信号则是低空信息损失率大,高空信息损失率小. 关键词： 滤波 高度场 信息损失率     

THz波在金属镀层空芯波导中传输的理论和实验研究

本文基于微扰法求得不同金属镀层空心圆波导中各模式的损耗系数,对金属镀层空芯波导中THz波传输损耗随金属材料、波导结构等参数的变化关系进行了数值模拟.根据数值分析结果,优化设计并拉制了内径为1.1 mm的镀银空芯波导,实验测得当THz波的频率为2.5 THz时,传输损耗为8.6 dB/m,实现了THz波短距离的有效传输. 关键词： 太赫兹波 金属空芯波导 传输损耗     

The influence of compressive stress applied by hard coatings on the power loss of grain oriented electrical steel sheet

To reduce the core loss of electrical steel the vacuum arc ion plating technique has been used to deposit titanium nitride (TiN) layers on highly grain oriented electrical steel sheets. The layer thickness, the stresses of layers and coated sheets and the achieved reduction in core losses have been measured as functions of coating duration and applied bias voltage. Well adhered layers with high compressive stress up to 6.8 GPa have been produced. With increasing bias voltage the layer thickness decreases and the intrinsic stress of the layers increase. A further increase of bias voltage leads to a drop in stress due to thermal relaxation. In general, the tensile stress of the coated sheets rises with increasing layer thickness while the core loss of the coated material decreases with increasing tensile stress of the steel sheet and increasing bias voltage. The highest reduction of core loss has been found to be 28% (from P_1.7=0.86 W/kg for commercially coated HGO electrical steel sheet with glass film to 0.62 W/kg for TiN coated material) and is due to the reduction of excess loss only.