A Ramsey theorem for metric spaces

We show the Ramsey property of the metric spaces $(V,d)$ where $1\le d(x,y)\le 3$ ($x\ne y$).     

应用相位移法的二维光栅测量

本文介绍了二种二维位移测量的光栅方法。测试系统采用CCD摄象系统记录正交光栅图象,通过调整摄象机变焦镜头的放大倍数来控制采样的空间频率。采样后用数字信号处理的方法,通过软件手段实现水平向和垂直向光栅信号的分离,然后运用了相位移技术及载波—相位移技术得到二维位移。所开发的测试系统除具有高精度、高灵敏度的特点外,还具有较高的空间分辨率。     

SOME RESULTS ABOUT COVERING PROPERTIES OF PRODUCTS

ＳＯＭＥ ＲＥＳＵＬＴＳ ＡＢＯＵＴ ＣＯＶＥＲＩＮＧ ＰＲＯＰＥＲＴＩＥＳ ＯＦ ＰＲＯＤＵＣＴＳ ￥ＪＩＡＮＧＪＩＧＵＡＮＧ;ＴＥＮＧＨＵＩＡｂｓｔｒａｃｔ：Ｔｈｅｆｏｌｌｏｗｉｎｇｒｅｓｕｌｔｓａｒｅｐｒｏｖｅｄ：１．ＬｅｔＸｂｅａｓｃｒｅｅｎ...     

Conduction mechanism of metal-TiO2–Si structures

The conduction model has been proposed for the metal-TiO₂–Si (MIS) structures. Rutile films have been prepared on Si substrates by magnetron sputtering of TiO₂ target and annealing in the air at temperatures T?=?800 and 1050 K. The current-voltage (CVC) and capacitance-voltage characteristics of the structures have been measured over the range of T?=?283–363 K. At positive potentials on the gate, the conductivity of the MIS structures is determined by the space charge-limited current in the dielectric layer.     

Effect of epitaxial crystallization on packet-like space charge characteristics in low-density polyethylene under multi-field coupling conditions

In order to study the effect of epitaxial crystallization on charge transport in low-density polyethylene (LDPE) under multi-field coupling conditions, three typical epitaxial crystallizations, namely disorder (glass substrate), crossover (isotactic polypropylene substrate), and parallel (polytetrafluoroethylene substrate), were prepared and denoted as LD-G, LD-iPP, and LD-PT, respectively. Packet-like space charge through samples was analyzed by the pulsed electro-acoustic (PEA) method. It is shown that different microscopic surface morphologies appeared in the LDPE samples with different epitaxial crystallizations, which, however, do not change the crystalline structure of the bulk. Packet-like space charge phenomena were observed and the distortion field increased with the temperature which could be attributed to the larger amount of charge injection in a shorter period. The differences of the amount and injection rate of the space charge were explained and verified considering the typical chain alignment of epitaxial crystallization, which, in our opinions, contributes to the pass over of positive charge in LD-iPP samples.     

对碎裂结构岩体似连续介质特征的一点研究

通常情况下认为碎裂结构的岩体具有非连续介质的特征。但是随着西部大量水电工程的勘查和建设,遇到了一类比较特殊的岩体,这类岩体中裂隙发育,结构面间距很小,按照国标划分为碎裂结构岩体,但是其本身又具有较高的力学性质,表现为具有较高的变形模量、抗剪强度参数和完整性系数,并且具有似连续介质的特征,这与通常的碎裂结构岩体有本质的区别。本文将利用两个实例工程对这一现象进行初步的分析,得到了水电工程可利用岩体的一种新的评价方法。     

Relating geologic units and mobility system kinematics contributing to Curiosity wheel damage at Gale Crater,Mars

Curiosity landed on plains to the north of Mount Sharp in August 2012. By June 2016 the rover had traversed 12.9 km to the southwest, encountering extensive strata that were deposited in a fluvial-deltaic-lacustrine system. Initial drives across sharp sandstone outcrops initiated an unacceptably high rate of punctures and cracks in the thin aluminum wheel skin structures. Initial damage was found to be related to the drive control mode of the six wheel drive actuators and the kinematics of the rocker-bogie suspension. Wheels leading a suspension pivot were forced onto sharp, immobile surfaces by the other wheels as they maintained their commanded angular velocities. Wheel damage mechanisms such as geometry-induced stress concentration cracking and low-cycle fatigue were then exacerbated. A geomorphic map was generated to assist in planning traverses that would minimize further wheel damage. A steady increase in punctures and cracks between landing and June 2016 was due in part because of drives across the sharp sandstone outcrops that could not be avoided. Wheel lifetime estimates show that with careful path planning the wheels will be operational for an additional ten kilometers or more, allowing the rover to reach key strata exposed on the slopes of Mount Sharp.     

The Interpolation Problem on the Maximal Ideal Space of H~∞

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Plücker-type relations for orthogonal planes

We explore a Plücker-type relation which occurs naturally in the study of maximally supersymmetric solutions of certain supergravity theories. This relation generalises at the same time the classical Plücker relation and the Jacobi identity for a metric Lie algebra and coincides with the Jacobi identity of a metric n-Lie algebra. In low dimension we present evidence for a geometric characterisation of the relation in terms of middle-dimensional orthogonal planes in Euclidean or Lorentzian inner product spaces.