Motion estimation of indoor robot based on image sequences and improved particle filter

Robot motion estimation is fundamental in most robot applications such as robot navigation, which is an indispensable part of future internet of things. Indoor robot motion estimation is difficult to be resolved because GPS (Global Positioning System) is unavailable. Vision sensors can provide larger amount of image sequences information compared with other traditional sensors, but it is subject to the changes of light. In order to improve the robustness of indoor robot motion estimation, an enhanced particle filter framework is constructed: firstly, motion estimation was implemented based on the distinguished indoor feature points; secondly, particle filter method was utilized and the least square curve fitting was inserted into the particle resampling process to solve the problem of particle depletion. The various experiments based on real robots show that the proposed method can reduce the estimation errors greatly and provide an effective resolution for the indoor robot localization and motion estimation.

     

长庆气田钻井施工中的问题及对策

根据长庆气田钻井施工中存在的问题,归纳出了施工中经常出现的一些技术难点,如漏失严重,钻具易刺、断,钻头断齿等。在认真分析该区块各个层位的地层和岩性特点基础上,针对这些难点提出了相应的解决办法,包括钻头选型,转速和钻压值的确定,低固相、无固相钻井液的应用,钻具管理,钻遇漏层时采取的相应措施等,并对今后在该区的钻井工作提出了建议。     

The role of rare earth elements in controlling sulfide morphology and transverse impact properties of steels

Addition of mischmetal into ingot mould and melting bath in steelworks or laboratory. Identification of type, shape, distribution, and size of the inclusions. Inspection of transverse impact values in relation to other factors.     

Cerium carbide in steel

Cerium carbide was found in steel. It has been investigated and identified by means of metallography, electron microprobe, Auger spectra, X-ray diffraction technique and electrolytic separation. The results obtained can be summarized as follows: When the amount of cerium is about 4 times the total amount of oxygen and sulfur, cerium carbide (CeC₂) of a dark grey to black colour forms in steel. It is distributed along the grain boundaries, and is rearranged in working direction after rolling or forging. CeC₂ in steel contains a certain amount of iron, oxygen and some sulfur, also chromium if it is available in the matrix. Cerium carbides are unstable, oxidize in air and decompose in water. It is difficult to separate them from the matrix by the electrolytic method. When steel is held at high temperatures, CeC₂ will change into Fe₄Ce₄C₇ of a light yellow colour. It is much more stable than CeC₂. When steel containing CeC₂ is heated in an oxidizing atmosphere, the CeC₂ will easily be changed into cerium dioxide. This Ce-oxide contains carbon. As soon as Ce-carbide forms in steel, the carbon needed for cementite is decreased. Therefore the pearlite content in steel will be correspondingly decreased.     

Global finite-time stabilization for a class of high-order nonlinear systems with multiple unknown control directions

This paper considers the problem of the global finite-time stabilization for the high-order nonlinear systems with unknown control directions. Due to the uncertainty of control directions, the paper analyzes all possible conditions of the directions. The Lyapunov-based logic switching rule ensures that we can find the correct control directions. The adaptive switching controller with a switching parameter which is to be tuned online guarantees that the derivative of Lyapunov function is less than a negative definite function and the closed-loop system is globally finite-time stable. The effectiveness of the proposed method is illustrated by an example.     

Metallography of telluride on free cutting steel

The results of investigation and analysis of telluride and sulfides in free cutting steel containing tellurium and sulfur can be summerized as follows. No tellurium is found in steel matrix. All the tellurium exists in solid solution in manganese sulfide. The extra amount of tellurium in excess of the solubility in manganese sulfide exists as MnTe in steel. The tellurium content in manganese sulfide is 2.5 wt% on average, and the sulfur content in MnTe is about 3 wt %. In annealed steel, the content of iron solutionized in MnS (steel containing 1–2 % Mn) and in MnTe are both about 2 wt %. MnTe usually forms complex inclusions with MnS. The greater the Te/S, the higher the MnTe content in the complex inclusions. There is no single phase MnTe in steel with Te/S as high as 0.84. When steel is hot worked, MnTe deforms more easily than MnS. MnTe appears light grey in a bright field, and opaque in a dark field. In cast steel it is anisotropic and in forged steel it is isotropic under polarized light. In cold drawn steel, most of the MnS is anisotropic and remained so after annealing at 1100°C. If Te/S in steel is too high, the MnTe formed is prone to stretch in the working direction during press work. Hence, in so far as controlling the shape of the sulfide with the aid of tellurium is concerned, a Te/S of about 0.1 is appropriate. When the MnTe and MnS in steel are separated electrolytely in the four different solutions used in this work, the equilibrium potential of MnS is relatively positive, and that of MnTe is relatively negative in comparison with iron. When an organic solution (No. 3) is used, the MnS in steel can be almost completely and MnTe partly separated.     

北京正负电子对撞机人身安全联锁系统的改进

本文介绍北京正负电子对撞机人身安全联锁系统的改进，主要叙述了人身安全联锁的要求和新系统方案的确定，改进后的新系统不仅提高可靠性，增强了系统的可维护性及信息传递的准确性，还实现了人身安全联锁系统与中央联锁系统的联网通讯。     

Metallography and properties of cerium-iron intermetallics in steel

Samples of steel containing Ce-Fe intermetallics were prepared in our laboratory. The Ce-Fe intermetallics were identified with metallograph and electron microprobe, and their possibilities of separation using the electrolytic method were investigated. CeFe₂ phase in steel is light yellow in a bright field, opaque in a dark field, and is isotropic in polarized light. The colour of the Ce₂Fe₁₇ phase is the same as that of the α-iron matrix in a bright field, it is also opaque in a dark field, but anisotropic in polarized light. These phases are electrolysed more easily than the α-Fe matrix during electrolytic separation. On heating at high temperatures in an oxidizing atmosphere, these Ce-Fe phases are transformed to Ce₂O₃. When the steel contains a higher amount of rare earths, RE-inclusion containing carbon may appear.     

基于组播和操作意图冲突检测的协同实验

针对目前的虚拟实验系统无法解决多用户同步协同实验的问题,设计了协同实验通信架构,提出了实验操作一致性处理方法.协同实验通信架构采用IP组播来减少群组通信所需带宽,并利用组播地址分配算法和无效组播地址回收算法使得组播地址可以动态分配和循环使用;实验操作通过附加环境参数并且按照时间戳和优先级的顺序执行,保证了所有协同参与者处结果一致,利用操作意图冲突检测机制来消除操作意图冲突.通过在现有的数字逻辑虚拟实验系统中实现协同实验并进行实验,结果表明,采用文中方法可有效地解决虚拟实验系统中协同实验问题.