液晶空间光调制器相位调制特性研究

研究了美国BNS公司生产的Modal P256反射型电寻址液晶空间光调制器的相位调制特性和时间响应特性.采用He-Ne激光作光源,建立迈克尔孙干涉光路观察波前相位变化,给出器件的相位调制特性曲线.分析测量了器件的相位响应不一致性和像素间的相位交连.通过测量液晶器件对方波和正弦控制信号的相位响应延迟,分析了液晶空间光调制器(LC-SLM)的时间响应特性.理论分析与实验结果说明:在特定的入射偏振条件下,LC-SLM实现纯相位调制,可用作高分辨力波前校正器件,然而极慢的响应速度和极低的时间带宽限制了它在动态变化波前相差校正中的应用.     

哈特曼波前传感器的自动孔径搜索与匹配方法

为了使夏克-哈特曼波前传感器(SHWFS)能保证精度的同时又能获得更大的动态范围,介绍了一种用于SHWFS的自动子孔径搜索与匹配算法.该方法在实施时,先根据待测量图像计算背景阈值,然后以减闽值后的图像中心位置的一个光斑为参考光斑的参考中心,按图像的横、纵方向依次搜索其它光斑点,接着将搜索的结果拼接起来得到所有孔径的分布,最后根据两幅图像得到的各自的子孔径分布按横、纵方向平移进行配准,以达到最优的匹配结果.文中利用实验对本论文提出的方法进行了验证.结果表明,本文提出的方法能够实现SHWFS的子孔径搜索与匹配,提高哈特曼的动态范围.     

Containers monitoring through the Physical Internet: a spatial 3D model based on wireless sensor networks

The Physical Internet concept was developed to address the current unsustainability problem of logistic systems. The key elements are the encapsulation and the handling of world-standard smart green modular containers (π-containers) throughout an open global logistic infrastructure. Logistic processes such as partial loading/unloading or splitting/merging of π-containers play an important role for a successful Physical Internet. However, the large variety of transformation processes can introduce desynchronisation between the physical and informational flows, i.e. the real composition of a composite π-container (a set of stacked π-containers) can differ of the information stored in the supply chain management system. To overcome this problem, this paper proposes a system to generate and maintain automatically a virtual three-dimensional layout reflecting the spatial distribution of π-containers. The proposed approach uses smart π-containers equipped with wireless sensor nodes. The relative position of π-containers can be determined by the neighbourhood relationships between the sensor nodes. From this information, a constraint set is formulated in a Constraint Satisfaction Problem where each solution is a potential loading pattern. The methodology is developed and computational experiments are proposed, as a proof-of-concept. The results show that our proposed method yields quick and satisfactory results.     

基于均匀设计及非线性偏最小二乘法的非闭合电极ECT传感器参数优化设计

提出了一种非闭合电极电容层析成像(ECT)传感器结构参数的优化方法.采用均匀设计结合非线性偏最小二乘(NPLS)回归,提取传感器结构参数(电极极板的宽度 L、绝缘外壳的壁厚δ1.、屏蔽罩与绝缘外壳间距δ2及绝缘外壳材料的相对介电常数ε)与待优化指标(敏感场的均匀度及灵敏度指标p1、最大与最小电容的比值 K)间的函数关系,建立相应的优化目标泛函,通过对优化目标泛函的求解,最终获得传感器结构参数的最优值.并以 10 电极非闭合电极 ECT 传感器为研究对象,进行了结构参数的优化设计,根据优化结果设计制作了非闭合电极 ECT 传感器,对其成像进行了仿真与实测.结果表明,参数优化后的传感器图像重建质量优于未优化的传感器.     

SectionBuilder: An innovative finite element tool for analysis and design of composite rotor blade cross-sections

SectionBuilder is a finite element based tool for analysis and design of composite rotor blade cross-sections. The tool can create the cross-sections with parametric shapes and arbitrary configurations. It has the ability to generate single- and multi-cell cross-sections with arbitrary lay-ups where the material properties for each layer can be defined on the basis of the design requirements. It can create the variation of thickness of skin and D-spars for rotor blades by considering ply drops. Cross-sections are often reinforced by core material for constructing realistic rotor blade cross-sections. The tool has the ability to integrate core materials into the cross-sections. After meshing the cross-section, the tool determines the sectional properties using finite element analysis. This tool computes sectional properties including stiffness matrix, compliance matrix, mass matrix, and principal axes. A visualization environment is integrated with the tool for visualizing the stress and strain distributions over the cross-section. The detail about the development steps and application of SectionBuilder is presented in this paper.     

采用国际标准的冷冻集装箱性能测试室的改进设计及分析

主要依据国际标准ISO1496-2及ATP协议(国际易腐食品运输及其运输专用装备的协议)改进设计并建造了一个用于冷冻集装箱热工性能测试的试验系统.通过与原试验系统的比较分析,完成了环境室空气处理方案设计、测试用制冷系统的更新配置及温湿度控制方法的调整,并顺利地进行了漏热试验与冷机试验的项目考核.     

A new discrete Kirchhoff-Mindlin element based on Mindlin-Reissner plate theory and assumed shear strain fields—part I: An extended DKT element for thick-plate bending analysis

This is the first of a two-part paper on plate bending elements with shear effects included. This paper presents a new three-node, nine-d.o.f. triangular plate bending element valid for the analysis of thick to thin plates. The element, called DKMT, has a proper rank (contains no spurious zero-energy modes), passes the patch test for thin and thick plates in an arbitrary mesh and is free of shear locking. Very good results have been obtained for thin and thick plates' by the element. An extended DKQ element for thick-plate bending analysis is evaluated in Part II.²⁴     

A new discrete Kirchhoff-Mindlin element based on Mindlin–Reissner plate theory and assumed shear strain fields—part II: An extended DKQ element for thick-plate bending analysis

This is the second part of a two-part paper on plate bending elements with shear effects included. This paper presents a new four-node, 12-d.o.f. quadrilateral plate bending element valid for the analysis of thick to thin plates. The element called DKMQ, has a proper rank (contains no spurious zero-energy modes), passes the patch test for thin and thick plates in an arbitrary mesh and is free of shear locking. Very good results have been obtained for thin and thick plates by the element. An extended DKT element for thick-plate bending analysis is evaluated in Part I.¹⁹     

Optimization of acyclovir oral tablets based on gastroretention technology: Factorial design analysis and physicochemical characterization studies

The purpose of this research was to prepare a floating drug delivery system of acyclovir. Floating matrix tablets of acyclovir were developed to prolong gastric residence time and increase its bioavailability. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose 4000, Compritol 888. Sodium bicarbonate was used as a gas-generating agent. A 3² factorial design using the Design Expert Software (version 7.1.6) was applied to optimize the drug release profile systematically. The amounts of hydroxypropylmethylcellulose 4000 (X₁) and Compritol 888 (X₂) were selected as independent variables and the percentage drug released in 1 (Q₁), 6 (Q₆), and 12 (Q₁₂) h as dependent variables. The results of factorial design indicated that a high level of both hydroxypropylmethylcellulose 4000 (X₁) and Compritol 888 (X₂) favors the preparation of floating controlled-release of acyclovir tablets. Also, a good correlation was observed between predicted and actual values of the dependent variables chosen for the study. By fitting the data into zero-order, first-order, and Higuchi models, we concluded that the release followed Higuchi diffusion kinetics. Storage of the prepared formulations at 40°C/75% relative humidity for 3 months showed no significant change in drug release profiles and buoyancy of the floating tablets. We can conclude that a combination of hydroxypropylmethylcellulose 4000, Compritol 888, and sodium bicarbonate can be used to increase the gastric residence time of the dosage form up to 12?h. These floating tablets seem to be a promising gastroretentive drug delivery system.