Active Control of Free Paraboloidal Membrane Shells Using Photostrictive Actuators

The paraboloidal membrane shell with free boundary condition is actively controlled using photostrictive actuators which can provide contactless actuation under the illumination of ultraviolet light. The governing equations of the paraboloidal shell laminated with paired photostrictive actuators are established based on membrane approximation. The modal control actions of meridional/circumferential actuators are respectively formulated and evaluated by case studies. Constant light intensity related to the velocity of the shell is adopted, and then the governing equations are written in a closed-loop form which can be solved with Newmark-β method. Considering the multi-field coupling behavior of photostrictive actuators, time histories of transverse displacement and control light intensity are simulated and evaluated. The results show that photostrictive actuators can effectively control the vibration of the paraboloidal membrane shell, and the photostrictive actuators oriented along circumferential direction can give better control effect than photostrictive actuators placed along the meridional direction.

Assessment and Prediction of Thermodynamic Functions of Compounds in Sialon System

According to the quasi paraboloid rule, a computer program was developed and the Gibbs free energy functions of some compounds in Sialon system were assessed and predicted. It makes the theoretical design of the Sialon materials possible.

Effect of Porosity on the Wind Loads on a Hyperbolic Paraboloid Canopy Roof

A discussion is made of the wind force coefficients for designing the main wind force resisting systems of H.P. （Hyperbolic-Paraboid）-shaped porous canopy roofs on the basis of a wind tunnel experiment. Roof models with a number of small circular holes were made of nylon resin using laser lithography. The porosity was changed from 0 （solid） to 0.4. Besides the porosity, the geometric parameters of the models were the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments acting on a model were measured by a six-component force balance in a turbulent boundary layer. The results indicate that the porosity significantly reduces the wind loads. The design wind force coefficients for porous canopy roofs can be provided by those for solid roofs with the same configuration multiplied by a reduction factor. The proposed wind force coefficients are verified by a comparison of the load effect predicted by the proposed wind force coefficients with the maximum load effect obtained from dynamic analyses using the time history of wind force and moment coefficients. The axial forces induced in the columns supporting the roof are regarded as the load effect for discussing the design wind loads.

Wind Loading on a Hyperbolic Paraboloid Free Roof

Wind loading on an H.P. （hyperbolic paraboloid） free roof has been investigated on the basis of a wind tunnel experiment. The roof models of 1 mm thickness were made of nylon resin using laser lithography. The parameters under consideration are the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments were measured by a six-component force balance in a turbulent boundary layer. Based on a combination of the lift and moment coefficients, the design wind force coefficients, CNW^＊ and CNL^＊, on the windward and leeward halves of the roof are proposed. Focus is on the column axial forces induced by wind loading as the load effect for discussing the design wind loads, assuming that the roof is rigid and supported by four comer columns. Indeed, two pairs of CNW^＊ and CNL^＊, generating the maximum tension and compression in the columns, are provided for each of the two or three wind directions parallel to the roof＇s diagonal lines. The proposed values of the wind force coefficients are compared with the specified values in the Australia/New-Zealand Standard for a limited range of rise to span ratio.

Theories and Analyses Thick Hyperbolic Paraboloidal Composite Shells

This paper presents the stress resultants of hyperbolic paraboloidal shells using higher order shear deformation theory recently developed by Zannon [1]-[3]. The equilibrium equations of motion use Hamilton’s minimum energy principle for a simply supported cross-ply structure by Zannon (TSDTZ) [2] [3]. The results are calculated for orthotropic, two-ply unsymmetrical [90/0] shells. The extensional, bending and coupling stiffness parameters are calculated using MATLAB algorithm for laminated composite hyperbolic paraboloidal shells. A comparison of the present study with other researchers in the literature is given, and is in good agreement.

Bioconvection Mangnetohydrodynamic Tangent Hyperbolic Nanofluid Flow with Quartic Chemical Reaction Past a Paraboloid Surface

In this numerical study,the effect of quartic autocatalysis type of chemical reaction,buoyancy force and thermal radiation phenomenon and magnetic effect on tangent hyperbolic nanofluid past an upper horizontal surface of a paraboloid has been studied.By considering the Buongiorno model approach,a diffusion of unequal coefficients in the presence of gyrotactic microorganism is discussed.Implementation of microorganism’s idea is used to stabilize the nanoparticles through bioconvection.The modeled PDEs of the problems are converted into nonlinear ODEs with the assistant of the similarity transformations.To tackle nonlinear ODEs,MATLAB package bvp4c is used.In addition,a hallmark of the Matlab code with the reported results in the literature is achieved by benchmarking.The variations in motion,concentration,temperature,and motile density due to sundry parameters have been analyzed in-depth via graphs.Our analysis shows that the density profile of motile of microorganism is hiked with an increment in the bioconvection Rayleigh number but decreases for higher thermal Grashof number.

Surface registration algorithm for rapid detection of surface thermal deformation of paraboloid antennas

In order to obtain and master the surface thermal deformation of paraboloid antennas,a fast iterative closest point( FICP) algorithm based on design coordinate guidance is proposed,which can satisfy the demands of rapid detection for surface thermal deformation. Firstly,the basic principle of the ICP algorithm for registration of a free surface is given,and the shortcomings of the ICP algorithm in the registration of surface are analysed,such as its complex computation,long calculation time,low efficiency,and relatively strict initial registration position. Then an improved FICP algorithm based on design coordinate guidance is proposed. Finally,the FICP algorithm is applied to the fast registration test for the surface thermal deformation of a paraboloid antenna. Results indicate that the approach offers better performance with regard to fast surface registration and the algorithm is more simple,efficient,and easily realized in practical engineering application.

Numerical and Experimental Investigation of an Elliptical Paraboloid Shell Model

For practical engineering purpose, a new flat shell element baptized （ACM_Q4SBE1） is presented in this paper. The formulated element can be used for the analysis of thin shell structures; no matter how the geometrical shape might be. Tests on standard problems have been examined. Since, the analysis of thin shell structures has generally been purely carried out on a theoretical basis; it is of importance to present some experimental results of an elliptical paraboloid under uniformly distributed load pressure. The results obtained from both numerical and experimental work are presented.

A Yield Mapping Procedure Based on Robust Fitting Paraboloid Cones on Moving Elliptical Neighborhoods and the Determination of Their Size Using a Robust Variogram

The yield map is generated by fitting the yield surface shape of yield monitor data mainly using paraboloid cones on floating neighborhoods. Each yield map value is determined by the fit of such a cone on an elliptical neighborhood that is wider across the harvest tracks than it is along them. The coefficients of regression for modeling the paraboloid cones and the scale parameter are estimated using robust weighted M-estimators where the weights decrease quadratically from 1 in the middle to zero at the border of the selected neighborhood. The robust way of estimating the model parameters supersedes a procedure for detecting outliers. For a given neighborhood shape, this yield mapping method is implemented by the Fortran program paraboloidmapping.exe, which can be downloaded from the web. The size of the selected neighborhood is considered appropriate if the variance of the yield map values equals the variance of the true yields, which is the difference between the variance of the raw yield data and the error variance of the yield monitor. It is estimated using a robust variogram on data that have not had the trend removed.

不同施肥方法对马来沉香和土沉香苗期根系生长的影响

以珍贵树种马来沉香、土沉香1年生播种苗木为材料进行试验,研究指数施肥、平均施肥对2种沉香苗期根系生长动态及对N的响应特征。结果表明,经氮素处理的马来沉香、土沉香的根系生物量、根系长度、根系表面积、根系平均直径、根体积等指标均显著高于对照处理(P<0.05)。经指数施肥处理的苗木根系生长及各形态指标均高于平均施肥处理。同一时期在相同施肥处理方式下,马来沉香苗根系生长及根系形态指标值均高于土沉香。洛伦兹模型对不同施肥方法处理下马来沉香、土沉香苗木生长指标与根系生物量进行拟合,具有较高的R2(0.95—0.99)和较低的RSMD(0.538—2.352);抛物面模型对不同施肥方法处理下马来沉香、土沉香苗木生长指标与比根长进行拟合,具有较高的R2(0.92—0.99)和较低的RSMD(3.218—6.692)。

汽车前照灯近光灯系统的比较

本文根据汽车前照灯近光系统的发展,对反射式系统和投射式系统近光灯的区别以及其同一系统中不同类型的前照灯近光进行了比较。

三元系中拟抛物面规则及其实验验证

从热力学基本原理出发，经严格的数学推导，得到了三元系中摩尔组元自由能与组成的关系符合拟抛物面规则；并用固体电解质电池测定了Ｌａ－Ｃｏ－Ｏ三元系中若干中间化合物的标准生成自由能，验证了该规则的正确性。

色温星模拟器用抛物面离轴反射光学系统设计

为了在室内测试星敏感器对无穷远星光的跟踪能力,设计一款运用宽光谱色温光源通过平行光管来提供无穷远星光色温模拟的光学系统。该系统采用孔径离轴方式规避同轴系统存在的遮光比现象,主镜引用抛物面使得系统像质更加良好,同时结合楔形状半反半透型次镜解决了透射接收端的宽光谱消像散问题。设计指标要求为:工作波段400~900 nm,入瞳直径300 mm,焦距3150 mm,全视场角0.05°.实际测试结果表明:在次镜不引入非球面情况下,光学系统可实现反射端及透射端的传递函数均接近衍射极限;各视场的波像差均方根值均优于λ/30(λ为系统主波长),出射光平行度优于1″的指标要求。

双曲抛物面组合扭壳屋盖施工技术

对空间大跨度组合扭壳屋盖结构的施工过程从屋盖的空间定位、内架的搭设、钢筋的安放与绑扎、混凝土的浇筑、预应力筋的张拉及内架的拆除等方面进行详细阐述,通过采用空间三维坐标控制技术、合理的支撑体系设计、对钢筋绑扎及预应力筋的精确定位、混凝土浇筑区域的合理划分及确定拆模顺序等,为实现设计意图、满足功能要求及保障施工期的安全奠定良好的基础。

折反射全景成像系统

折反射全景成像系统能实现大于半球视场的全景成像 ,在视频会议、监视和机器人导航等领域有着广泛的应用。本文介绍了折反射全景成像系统的原理和主要类型 。

大型抛物面天线精密校准测量自动化和精度

本文提出了T2000电子经纬仪与PC-1500计算机联机系统（简称TPC系统）及工作原理。该系统能实现对大型设备精密校准测量的数据采集，传送、处理自动化。作者成功地把该系统用于抛物面天线的校准测量。文中详细说明了数据处理方法，分析了各项主要因素对天线校准测量的误差影响。结论指出：TPC系统能达到±0.6毫米的点位精度，不失为用于大型设备安装或精密校准测量的一种先进手段。

旋转抛物面薄透镜组的光心

为了研究旋转抛物面薄透镜组的光心,首先讨论了单个抛物面薄透镜的光心,在此基础上,根据等效光学系统理论,对旋转抛物面薄透镜组的光心定义、性质和位置进行了详细的探讨和研究,发现旋转抛物面薄透镜组的光心位置取决于两抛物面薄透镜的间距、抛物面的形状、两透镜材料及其周围介质的折射率,最后讨论了空气中旋转抛物面薄透镜组在几种特殊情况下的光心位置.

抛物面反射准直镜的光源位置容差估算

给出了光源位置存在纵向和横向离焦时的反射波面近似表达式,进而导出了以平面和球面作为参考波面时的光源位置容差估算公式。以实际例子对容差进行了估算,其结果与经验数据相符。

太阳能收集和传输的研究

对高精度太阳能抛物面镜收集器和大孔径低损耗PMMA／Ag泄漏型空芯光纤进行了设计与研究，安装在收集器上的光电追踪器保证了入射光线聚焦在抛物面轴上，有利于聚焦光斑有效地传输到空芯光纤内。与传统的太阳能利用装置相比较，本装置不需要进行能量转换，因此效率高，结构简单，可以实现聚焦后太阳能的远距离高效传输。

一种基于复合抛物面聚光器的太阳能幕墙模块结构

项目组设计了一套选择性聚光光伏系统及其智能控制APP,能够广泛应用于现代城市建筑的外表面,提供一种综合采光、隔热与太阳能利用的解决方案。相比于传统光伏幕墙具有光伏板使用面积减少64%;能够通过自主调节工作模式,保证光伏板工作温度不超过50℃,以避免墙体过热的优势。