Dual frequency liquid crystals: a review

We review the recent progress in developing high performance dual frequency liquid crystal (DFLC) materials. A new figure of merit is derived for evaluating the DFLC performance. The dielectric relaxation and electro-optical properties of several high performance compounds, which possess a positive dielectric anisotropy at low frequencies and a relaxation frequency in the kilohertz region, are presented. Potential applications of these compounds are discussed. Compounds with a negative dielectric anisotropy were also compared and discussed. Two experimental DFLC mixtures were demonstrated with one intended for room temperature operation and another for elevated temperature operation.     

基于Hoek-Brown强度准则磷矿体开采稳定性分析

磷矿是保障精细磷化工生产和粮食供应的物质基础,而地下缓倾斜磷矿体的开采一直是个难题.该文以湖北兴山后坪矿段磷矿层地下开采为研究背景,采用有限差分软件FLAC3D,基于Hoek-Brown强度准则,对磷矿层的开采过程进行了数值模拟.首先进行单轴压缩模拟试验,求得各岩体的单轴抗压强度、弹性模量和泊松比,模拟试验结果和室内试验结果基本一致.然后研究了磷矿层开采过程中采空区围岩的应力变化情况、上覆岩体的位移规律和矿柱屈服区分布情况,从而评价采空区的稳定性.最后,分析了在缓倾斜磷矿体中实施浅孔房柱法开采的的可行性.     

细胞自动机位相展开算法用于三维传感

研究了细胞自动机算法用于复杂面形三维传感问题。提出采用调制度分析的方法构造二元控制模板，以确保细胞自动机算法能展开复杂位相场。给出了采用这种方法对口腔牙型测量的结果。     

垄断情形下的配套产品定价策略研究

本文中,我们建立了一个垄断情形下的配套产品的线性定价模型,分析当整个配套产品只由一个垄断厂商生产时,垄断者的最优定价策略.模型的分析结论表明,垄断者最优定价时,对主件定价较高,对配件定价较低,但两者均小于单独出售时的最优垄断定价.     

ACEL 六位数字屏显示暗室安全钟

开发研究了电致发光屏六位数字显示的数字钟，设计了电子线路并分析了它们的工作原理．它在彩色胶片和相纸生产的暗室中使用是安全的．     

激光片光三维传感的直接映射方法

提出了一种新的全场高度映射方法，利用激光片光产生的莫尔条纹的性质，拟合出两个映射曲面。通过这两个曲面方程，可同时直接得出ＣＣＤ探测器表面任意一点在实际世界坐标系中对应的高度和一维横向坐标。此方法具有极大的实用价值。     

High-pressure delta-Al(OH)3 and delta-AlOOH phases and isostructural hydroxides/oxyhydroxides: new structural insights from high-resolution 1H and 27Al NMR

In order to shed light on the proton distributions and order/disorder in high-pressure delta-Al(OH)3 and delta-AlOOH phases, two-dimensional, high-resolution 1H CRAMPS (FSLG)-MAS NMR and 27Al 3QMAS NMR spectra have been obtained. For delta-Al(OH)3, the 1H CRAMPS-MAS NMR revealed two peaks with an intensity ratio close to 2:1. The 27Al MAS and 3QMAS NMR suggest a single Al site with a well-defined local structure. For delta-AlOOH, the 1H and 27Al NMR indicate the presence of a single H and Al site each. These results are consistent with crystal structures refined from X-ray diffraction. For comparison, 1H MAS and CRAMPS-MAS NMR spectra were also obtained for several other hydroxides/oxyhydroxides, including In(OH)3 and InOOH that have similar structures to delta-Al(OH)3 and delta-AlOOH, respectively. These data not only provide additional insights into the proton distributions in these important crystal structure classes but also together provide a better defined quantitative correlation between 1H chemical shift and hydrogen-bonding O...O distance.     

Pressure and solvent induced low-temperature synthesis of monodisperse superparamagnetic nanocrystals: The case of Fe3O4 in alkanols

The synthesis of nanoparticles via the decomposition of organometallic compounds has been studied extensively, but the effect of pressure has received little attention. Here we firstly focus on the pressure effect, and utilize it as well as the solvent and temperature effects to develop a “green” cheap low-temperature (140–200 °C) strategy via the decomposition of iron oleate in alcohol (or other alkanols) using oleic acid as the protecting reagent. The obtained monodisperse Fe₃O₄ nanocrystals (NCs) exhibit satisfying superparamagnetism. The mechanism of the process has been investigated and it was shown both high pressure and alkanol as the solvent can facilitate the formation of magnetite NCs. Furthermore, the solvent used in the preparation can control the shape, size and dispersion of NCs. In addition, the effects of reactant concentration, reaction time, temperature, and the mol ratio of oleic acid on the Fe₃O₄ NCs have also been discussed.     

A Method for Obtaining Three-dimensional Images with Visual Reality of Real Objects

A new method to remove the shadows in laser triangulation and a computer model for three-dimensional images with visual reality of three-dimensional diffuse objects are presented. The methods for acquiring color data in optical three-dimensional sensing are discussed. A method for obtaining three-dimensional images with visual reality of real objects is presented. The principles,the system structure and the experimental results are provided.     

付立叶变换轮廓术中参数的优化选择

利用等效波长的概念对ＦＴＰ测量方法中的参数θ与载频ｆ０进行优化选择，保证了付立叶频谱中各级谱的完全分离与系统测量精度，运用空间带宽积的概念，实现了对ＦＴＰ测量系统中若干参数的最高允许值进行选择与限制，计算机模拟的结果验证了理论上的推导。