管板组合结构等效力学模型

通过将管板组合结构等效为正交各向异性板的方法,探讨该类结构的力学响应的计算方法.首先从平面问题本构方程出发,应用变形协调条件得到其等效材料参数,然后应用刚度分析法得到其等效厚度与等效密度,最后通过与3D有限元结果比较说明等效模型的正确性.     

Venlo型温室结构设计软件的开发与应用

目前市场上的温室结构设计软件存在无法按三维模型计算、施工图难以满足工程要求等不足,基于AutoCAD平台开发了用于Venlo型温室结构设计软件GreenHouse。GreenHouse操作方便、计算准确、功能齐全。软件分为前处理、核心计算和后处理三大模块,快速建模可提升建模效率,三维模型计算可提高内力分析的准确性,详细计算书和施工图的输出方便工程师应用,并以工程实例说明了软件的功能和应用情况。     

喷雾车计算机动态模拟中圆柱型储液罐中液体影响的动力模型

本文介绍了一种通过实验和分析建立储液罐中液体晃动影响的动力模型的方法．在车辆的计算机动力性能模拟中采用该模型可以计入液体晃动对整车的影响，从而提高模拟的精度     

供水不足地区园艺植物类温室自动灌溉系统的设计与试验

目前温室自动灌溉系统大多针对供水充足的稳定环境,为了提高供水不足情况的灌溉效率,设计了一种采用物联网的园艺植物类温室自动灌溉系统。计算流体力学模型能够模拟温室中土壤-植物-空气的水分交换过程,并且无须对历史数据的学习即可建立模型,将植物作为多孔介质与蒸腾源,采用一个二维瞬态计算流体力学模型预测植物的需水量。此外,设计一种考虑气孔阻力的子模块,基于灌溉与蒸腾作用之间的平衡来计算基质的含水量。在山东潍坊地区采用水仙花盆景进行试验,对供水充足与供水不足2种情况均进行了试验,试验结果显示,该模型能够有效地拟合温室内的微气候、植物活动参数与泥炭土基质势的变化趋势。     

基于等效刚度法的裂纹梁振动特性分析

针对含裂纹横向振动梁,采用包含裂缝位置及裂纹深度信息的裂纹梁等效弯曲刚度和等效剪切刚度模型,运用计算变截参数梁横向振动特性的半解析方法,计算了不同长高比的铁木辛柯梁在不同深度裂纹影响下的固有频率,将计算结果与有限元计算结果进行比较,验证了等效刚度模型的有效性,分析了裂纹对梁固有频率衰减的影响.     

用边界元法分析纳米硬度实验中的位错生成

利用边界积分方法及基于Peierls-Nabarro模型的位错理论,分析了理想纳米触头下位错的生成,得到了滑移原子层上相对滑移量、位错产生的临界载荷以及激发位错所需的激发能.导出了位错产生临界载荷的近似解析式,用于验证数值分析结果的有效性.该方法在连续力学的计算中引入了包含原子信息的层间势能函数,为分析多尺度的力学问题提供了有效的方法.     

喷雾车计算机动态模拟中圆柱型储液罐中液体影响的动力模型

本文介绍了一种通过实验和分析建立储液罐中液体晃动影响的动力模型的方法，在车辆的计算机动力性能模拟中采用该模型可以计入液体晃动对整车的影响，从而提高模拟的精度。     

基于GIS和地统计学的土壤养分空间变异特征研究——以新疆农七师125团为例

基于地理信息系统(GIS)和地统计学,以地理信息系统软件ArcGIS为平台,采用Geostatisical Analyst地统计分析模块中的Kriging插值方法研究了新疆农七师125团土壤养分的空间变异性.应用GIS能够将系统变量的属性数据同地理数据相结合,使大区域范围内进行地统计学分析变得较为方便,研究结果表明,全氮、有机质、速效磷、速效钾均具有中等的空间相关性,但变异尺度不同.分析中还发现Kriging插值模型的选择及Crossin-ValNation交叉验证的检验与系数修正均影响分析工作的结果精度.     

油气管道悬空沉降变形失效评估

管道在实际运行过程中常常受到因沉降变形导致的外部载荷作用,而已有的管道失效评估标准与方法大多局限于内压对管体的影响.针对油气管道悬空沉降变形问题采用力学模型、有限元分析、开挖试验等方法进行了系统研究,模拟了无缺陷和含缺陷悬空管道的应力分布,结果表明,缺陷在管道底部时等效应力最大.通过开挖试验获得了最大应力点的应力变化等试验数据,验证了有限元方法用于工程实践的可行性,指出在实际工程评估中尚需考虑缺陷位置、土质等因素的影响.     

储罐液体晃荡问题的有限元分析

采用有限元方法数值求解了任意容器内液体晃动的固有频率、模态和地震响应动力学问题。基于液体晃动的泛函极值原理,在晃动自由面上忽略液体的表面张力,对液体晃动有限元方程进行静态缩聚,计算了矩形容器内液体晃动的特征频率,并与解析解进行比较。研究表明,利用该方法计算的结果具有较高精确度,可以为研究储罐晃动动力特性分析提供参考。     

Global mineralogical and aqueous mars history derived from OMEGA/Mars Express data

Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.     

车-液耦合响应下液罐车稳定性控制仿真

为了提高液罐车行驶安全性、减少液罐车侧翻、失稳所带来的危害,对于液罐车在转向或换道时车-液耦合动态响应对整车稳定性的影响进行了研究。联合液体纳维斯托克斯和流动控制方程,应用计算流体动力学软件ANSYS/Fluent建立并求解液体晃动模型,通过结合液体晃动模型和三自由度液罐车刚体模型获得液罐车车-液耦合动力学模型,分析有无控制策略情况下,液体晃动对液罐车横向稳定性的影响。仿真结果表明:提出的模糊差动制动控制策略能够有效提高车辆抗侧翻能力,减少罐车运输过程中交通事故的发生,对液罐车运输有指导意义。     

Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.     

Magnetic fields at neptune

The National Aeronautics and Space Administration Goddard Space Flight Center-University of Delaware Bartol Research Institute magnetic field experiment on the Voyager 2 spacecraft discovered a strong and complex intrinsic magnetic field of Neptune and an associated magnetosphere and magnetic tail. The detached bow shock wave in the supersonic solar wind flow was detected upstream at 34.9 Neptune radii (R(N)), and the magnetopause boundary was tentatively identified at 26.5 R(N) near the planet-sun line (1 R(N) = 24,765 kilometers). A maximum magnetic field of nearly 10,000 nanoteslas (1 nanotesla = 10(-5) gauss) was observed near closest approach, at a distance of 1.18 R(N). The planetary magnetic field between 4 and 15 R(N) can be well represented by an offset tilted magnetic dipole (OTD), displaced from the center of Neptune by the surprisingly large amount of 0.55 R(N) and inclined by 47 degrees with respect to the rotation axis. The OTD dipole moment is 0.133 gauss-R(N)(3). Within 4 R(N), the magnetic field representation must include localized sources or higher order magnetic multipoles, or both, which are not yet well determined. The obliquity of Neptune and the phase of its rotation at encounter combined serendipitously so that the spacecraft entered the magnetosphere at a time when the polar cusp region was directed almost precisely sunward. As the spacecraft exited the magnetosphere, the magnetic tail appeared to be monopolar, and no crossings of an imbedded magnetic field reversal or plasma neutral sheet were observed. The auroral zones are most likely located far from the rotation poles and may have a complicated geometry. The rings and all the known moons of Neptune are imbedded deep inside the magnetosphere, except for Nereid, which is outside when sunward of the planet. The radiation belts will have a complex structure owing to the absorption of energetic particles by the moons and rings of Neptune and losses associated with the significant changes in the diurnally varying magnetosphere configuration. In an astrophysical context, the magnetic field of Neptune, like that of Uranus, may be described as that of an "oblique" rotator.     

船舶液货舱晃荡模拟系统研制

主要设计了船舶液舱晃荡模拟系统的机械结构、液压驱动系统以及信号输出控制系统。通过机械机构部分实现晃荡中心改变，液压系统与信号控制系统实现晃荡振幅、晃荡频率改变。系统的晃荡平台可以承载不同大小的模拟液舱，使实验多样性。最后进行了系统调试试验，分析系统误差产生原理，对以后的研究有着重要的指导意义。     

Venus ionosphere: photochemical and thermal diffusion control of ion composition

The major photochemical sources and sinks for ten of the ions measured by the ion mass spectrometer on the Pioneer Venus bus and orbiter spacecraft that are consistent with the neutral gas composition measured on the same spacecraft have been identified. The neutral gas temperature (Tn) as a function of solar zenith angle (chi) derived from measured ion distributions in photochemical equilibrium is given by Tn (K) = 323 cos(1/5)chi. Above 200 kilometers, the altitude behavior of ions is generally controlled by plasma diffusion, with important modifications for minor ions due to thermal diffusion resulting from the observed gradients of plasma temperatures. The dayside equilibrium distributions of ions are sometimes perturbed by plasma convection, while lateral transport of ions from the dayside seems to be a major source of the nightside ionosphere.     

液罐车稳定性最优控制仿真

针对重型液罐车在紧急避障或转弯时液体和车体相互耦合作用引发的侧翻危险,用势流理论建立液体晃动控制方程并求解液体晃动力和力矩,结合半挂车刚体模型,将液体晃动模型统一到液罐车整车模型中。在鱼钩工况下,对比分析装载等质量液体和固体在激励作用下对罐车稳定性的影响。在非稳态因素影响下,设计了最优控制策略,并进行TruckSim/Simulink 联合仿真分析。结果表明:最优控制策略提高了车辆的鲁棒性,对增强液罐车的稳定性具有指导意义。     

Superior conjunction of pioneer 6

Spectrograms of the radio signals from Pioneer 6 were taken as the spacecraft was occulted by the sun. The spectral bandwidths increased slowly at first, then very rapidly at 1 degree from the sun. In addition, six solar "events" produced marked increases of bandwidth lasting for several hours. The received signal power seemed unaffected by the solar corona.     

关于对"三个代表"重要思想的几个认识问题

“三个代表”重要思想,是基于对党和国家前途命运的深沉忧患,回应当代世界和中国新的发展变化,全面推进建设中国特色社会主义事业,实现中华民族伟大复兴的强大思想武器。作为与时俱进的理论创新成果,其在基本理论层面主要表现为综合创新;在政策措施层面,则主要表现为继发性创新。“三个代表”重要思想由理论精髓、思想内核、学说本体和政策展开4个层面构成了严谨的理论体系。     

Ion-Induced Morphological Changes in "Crew-Cut" Aggregates of Amphiphilic Block Copolymers

The addition of ions in micromolar (CaCl2 or HCl) or millimolar (NaCl) concentrations can change the morphology of "crew-cut" aggregates of amphiphilic block copolymers in dilute solutions. In addition to spherical, rodlike, and univesicular or lamellar aggregates, an unusual large compound vesicle morphology can be obtained from a single block copolymer. Some features of the spontaneously formed large compound vesicles may make them especially useful as vehicles for delivering drugs and as models of biological cells. Gelation of a dilute spherical micelle solution can also be induced by ions as the result of the formation of a cross-linked "pearl necklace" morphology.