Analyticity of the sine family with L p -maximal regularity for second order Cauchy problems

If the second order problem u（t） ＋ Bu（t） ＋ Au（t） = f（t）, u（0） =u（0） = 0 has L^p-maximal regularity, 1 〈 p 〈 ∞, the analyticity of the corresponding propagator of the sine type is shown by obtaining the estimates of ‖λ（λ^2 ＋ λB ＋ A）^-1‖ and ‖B（λ^2 ＋ λB ＋ A）^-1‖ for λ∈ C with Reλ 〉 ω, where the constant ω≥ 0.     

Optimal policies for inventory systems with discretionary sales, random yield and lost sales

We determine replenishment and sales decisions jointly for an inventory system with random demand, lost sales and random yield. Demands in consecutive periods are independent random variables and their distributions are known. We incorporate discretionary sales, when inventory may be set aside to satisfy future demand even if some present demand may be lost. Our objective is to minimize the total discounted cost over the problem horizon by choosing an optimal replenishment and discretionary sales policy. We obtain the structure of the optimal replenishment and discretionary sales policy and show that the optimal policy for finite horizon problem converges to that of the infinite horizon problem. Moreover, we compare the optimal policy under random yield with that under certain yield, and show that the optimal order quantity （sales quantity） under random yield is more （less） than that under certain yield.     

利用数值再现实现彩虹全息色差评价

为了在计算机制彩色彩虹全息图输出之前定量得到再现像的色彩保真度,提出了一种采用数值再现进行色差评价的方法.首先对彩虹全息图进行了频谱分析,得到再现参量与频谱分布之间的关系;然后采用频域滤波算法实现彩色彩虹全息图数值再现,得到再现像的相对功率谱分布;最后采用CIE1976UCS均匀颜色空间对再现像色差情况进行了计算.设计了7个色块并制作了计算机制真彩色彩虹全息图,以金卤射灯作为照明光源进行了光学再现实验,给出实验结果及分析.研究证明了采用数值再现方法实现对计算彩虹全息再现像光谱分布和色差进行计算分析是一种快速经济的方法.     

以发光二极管为背光源的平板显示对人体非视觉的影响

针对以发光二极管为背光源的平板显示对人体生理节律等非视觉的影响,采用节律因子评价模型设计了实验系统.通过全空间平均辐射法,采用国际电工委员会标准中平均图像电平的节目画面,测量显示不同图像时以发光二极管为背光源的平板显示器光辐射的节律因子.结果发现:以发光二极管为背光源的平板显示器在显示白场和大部分彩色图像时的节律因子为5.0以上,其非视觉效应比普通照明要强得多,且与显示的图像内容密切相关;该平板显示器的光学辐射对人体生理节律等非视觉具有不可忽视的影响.     

年报“补丁”之思

在每年上市公司年报的披露期间以及结束后的几个月,“年报打补丁”现象都会成为一道风景。今年,更不例外。 相关数据显示,截至5月15日,在2471家出具2012年年度财务报表的上市公司中,已经有86家上市公司先后发布了年报更正公告,占比3．5％。     

High optical-efficiency integral imaging display with a gradient-aperture parallax barrier

We propose a one-dimensional integral imaging (1DII) display that consists of a display panel and a gradient-aperture parallax barrier. The gradient-aperture parallax barrier is symmetrical, and its slit widths gradually increase from both sides to the middle. The leftmost and rightmost slits are used to fix the viewing angle, whereas the other slits are used to increase the optical efficiency. A prototype of the proposed 1DII display is developed. Its optical efficiency is higher than that of the conventional display, but the viewing angles are the same.     

三种固体转轮除湿系统的模拟比较

分别建立单级转轮系统、厚转轮系统以及两级转轮系统的模型.利用模型比较分析了三种系统的性能.结果显示两级系统处理的潜热、显热负荷和产生的冷量均为最大,但其COP在三者之中最低;厚转轮系统与单级系统的差异不显著.通过实际的两级除湿系统的实验结果,验证模拟结果的准确性.     

离心压气机叶片前缘几何形状对性能的影响

本文采用数值模拟的方法研究了不同的叶片前缘几何形状对离心压气机性能的影响,研究表明:圆形前缘与钝头前缘相比能提高压气机的流通能力,并使压比和效率有明显的提高,但同时也会使得工作范围变窄,而椭圆形前缘会使得性能得到进一步的提高.流场分析显示,圆形前缘和椭圆形前缘可以减小叶片前缘造成的分离损失,并减小出口尾迹的损失,从而使得效率提高.采用圆形前缘和椭圆形前缘可以使得从分流叶片前缘位置往后的主叶片的载荷分布比较平均,使得主叶片和分流叶片的载荷分布比较合理,同时椭圆形前缘还可以使得分流叶片的做功能力增加.     

Optical Defect in GaN-Based Laser Diodes Detected by Cathodoluminescence

GaN-based laser diodes （LDs） with 399 nm wavelength are grown on sapphire substrates by metal organic chemical vapour deposition （MOCVD）. Electroluminescence spectra of the fabricated LDs show that the LDs from some grown wafers failed to emit laser. The SEM and XRD results show the similar surface morphology and interface qualities of multi quantum wells （MQWs） and super-lattices between LDs that succeed and fail to emit laser. However, the cathodoluminescence （CL） measurements reveal a kind of optical defect rather than structural defect in un-emitted LDs. Further depth-dependent CL imaging observation indicates that such optical defects originate from the MQWs to the surface of LDs as a non-irradiative recombination centre that should cause the failure of laser emitting of LDs.     

声-地震耦合探雷技术分析

根据声-地震耦合原理,分析地震波与地雷的机械作用,并设计一个基于地震检波器串的探雷实验系统.把高顺性雷体与其上方的土壤视作一个质量-弹簧系统,用解析法分析其谐振机理.采用扬声器发出可扫频的单音正弦波穿透到地下土壤,作为系统信号激励源,采用地震检波器串测出地表震动速度.根据有无地雷处的地表震动速度幅频特性曲线,分析地雷对地表震动的影响.实验结果显示,地雷上方的地表震动速度要明显高于没有地雷的情况,该系统可用于声波探雷的进一步研究.