120吨转炉炉下道轨基础的适应性改造

介绍了银山型钢120吨转炉炉下道轨基础损坏的主要原因，提出了解决转炉炉下道轨基础酥松、基础预埋件与砼脱离及道轨变形的改造方案，并进行了有效实施。

250t转炉炉下道轨基础改造

介绍了造成250t转炉炉下道轨基础损坏的原因及后果,提出了一种解决转炉炉下渣坑两侧铸铁板脱落、混凝土剥落及轨道悬空的改造方案,并进行了实施。

Node scattering manipulation based on trajectory model in wireless sensor network

To deploy sensor nodes over the area of interest,a scheme,named node scattering manipulation,was proposed.It adopted the following method:during node scattering,the initial states of every node,including the velocity and direction,were manipulated so that it would land in a region with a certain probability;every sensor was relocated in order to improve the coverage and connectivity.Simultaneously,to easily analyze the process of scattering sensors,a trajectory model was also proposed.Integrating node scattering manipulation with trajectory model,the node deployment in wireless sensor network was thoroughly renovated,that is,this scheme can scatter sensors.In practice,the scheme was operable compared with the previous achievements.The simulation results demonstrate the superiority and feasibility of the scheme,and also show that the energy consumption for sensors relocation is reduced.

Dynamic Connectivity in Cislunar Communication Networking Based on Geosynchronous Orbit Relay Satellites

The architecture of cislunar multi-hop communication networks, which focuses on the requirements of lunar full-coverage and continuous cislunar communications, is presented on the basis of Geosynchronous Orbit (GEO) satellite network relays. According to the geographical distribution of the forthcoming Chinese Deep Space Measuring and Controlling Network (DSMCN), two networking schemes are proposed and two elevation angle optimization models are established for locating GEO relay satellites. To analyze the dynamic connectivity, a dynamic network model is constructed with respect to the time-varying characteristics of cislunar trunk links. The advantages of the two proposed schemes, in terms of the Connectivity Rate (CR), Interruption Frequency (IF), and Average Length of Connecting Duration (ALCD), are corroborated by several simulations. In the case of the lunar polar orbit constellation case, the gains in the performance of scheme I are observed to be 134.55%, 117.03%, and 217.47% compared with DSMCN for three evaluation indicators, and the gains in the performance of scheme II are observed to be 238. 22%, 240.40%, and 572.71%. The results validate that the connectivity of GEO satellites outperforms that of earth facilities significantly and schemes based on GEO satellite relays are promising options for cislunar multi-hop communication networking.

Railway Foundation Design Principles

There are a number of design procedures which have been developed to determine the appropriate thickness of trackbed layers on a railway track in order to reduce train induced stresses to an acceptable level thus ensuring that subgrade failure does not occur prematurely. This paper briefly describes four such procedures and compares the thickness of trackbed layers proposed by each for a number of hypothetical situations. To demonstrate further the suitability of each procedure, two existing sites in the UK are analysed and the trackbed layer thickness given by each procedure is then compared. The research shows that the procedures do not give consistent results. Subsequently it is suggested that it is important to consider other aspects in addition to the prescription of a suitable thickness of trackbed layers in any new build, renewal or remediation scheme.

A reconfigurable tracked mobile robot based on four-linkage mechanism

A novel reconfigurable tracked robot based on four-link mechanism was proposed and released for the complicated terrain environment. This robot was modularly designed and developed, which is composed of one suspension and one pair of symmetrical deployed reconfigurable track modules. This robot can implement multiple locomotion configurations by changing the track configuration, and the geometric theory analysis shows that the track length keeps constant during the process of track reconfiguration. Furthermore, a parameterized geometric model of the robot was established to analyze the kinematic performance of the robot while overcoming various obstacles. To investigate the feasibility and correctness of design theory and robot scheme, an example robot was designed to climb 45° slopes and 200 mm steps, and a group of design parameters of the robot were determined. Finally, A prototype of this robot was developed, and the test results show that the robot own powerful mobility and obstacle overcoming performance, for example, running across obstacle like mantis, extending to stride over entrenchment, standing up to elevate height, and going ahead after overturn.

The Space Infrastructure Vulnerability Cadastre:Orbital Debris Critical Loads

Orbital debris from over 50 years of human activity in space are threatening the operations of existing and future satellites and the sustainability of high-value satellite orbits. This technical memorandum calls for the development of a cadastre that depicts the vulnerability of critical satellite orbits to accumulating orbital debris. A space infrastructure vulnerability cadastre could serve as a governance tool for use by developers and operators of critical space infrastructures to better communicate the current and future vulnerability of high-value orbits to the accumulation of orbital debris. These high-value orbits are susceptible to 'loss' for decades or centuries if generation of orbital debris continues unabated. The concept of environmental critical loads is applied to heavily used orbits as a way to indicate acceptable debris density for satellite operations, and when debris density/risk thresholds approach unacceptable levels that reduce the probability of sustaining spacecraft operations in those orbits.

Orbit control strategy for Lagrange point orbits based on an analytical method

The periodic or quasi-periodic orbits around collinear Lagrange points present many properties that are advantageous for space missions. These Lagrange point orbits are exponentially unstable. On the basis of an analytical method, an orbit control strategy that is designed to eliminate the dominant unstable components of Lagrange point orbits is developed. The proposed strategy enables the derivation of the analytical expression of nonlinear control force. The control parameter of this strategy can be arbitrarily selected provided that the parameter is considerably lower than the negative eigenvalue of motion equations, and that the energy required keeps the same order of magnitude. The periodic or quasi-periodic orbit of controlled equations remains near the periodic or quasi-periodic orbit of uncontrolled equations.

Floquet-based design and control approach to spacecraft formation flying in libration point orbits

A method for spacecraft formation flying (SFF) design and control near libration point orbits was developed by making use of the Floquet theory for periodic orbits. Firstly, the Floquet theory used in libration point orbits was introduced and the coefficients of four Floquet periodic modes were proved to be nearly constant when the amplitude in z direction of earth-moon L1 halo orbits is less than 20000 km. On this basis, a configuration design approach to SFF in L1 halo orbits was proposed, and several types of special configurations were obtained with periodic mode 3 and mode 5 or mode 4 and mode 6. Then, in order to control the SFF configuration concisely, those coefficients of the 5 modes (except the stable one) must be kept constant. A stationkeeping method for SFF was developed, which controls 5 Floquet modes simultaneously. Finally, simulations showed that the Floquet-based approach of configuration design and control for SFF is effective, simple and convenient. The research may be of value for deep space explorations.