太空安全的概念、源起与规则研析

太空安全日益受到国际社会的关注,但“安全”一词,在不同语言背景下含义并不相同。汉语语境下的“安全”对应了英语语境下safety和security两个词汇。前者对应的是免受危险和风险,后者对应的是免受人为的威胁。联合国文件中并未使用space safety这一表述,仅有少量联合国文件在特定情况下援引或提及space security,这在某种程度上暗示其与防止外空军备竞赛有一定联系。space safety这一用语的出现,表明部分西方国家开始将其安全诉求包装、隐藏于普遍性的太空安全问题中,将自身安全关切国际化,试图通过相关领域的讨论推进有利于自己的国际规则,从而冲击、淡化乃至取代防止外空军备竞赛的谈判。在推进太空安全国际规则方面,中俄与美西方一直存在尖锐对立。太空安全国际规则目前散见于联合国有关外空条约和一些国际软法中。近些年来,通过联大决议并利用联合国平台来推进太空安全规则已经成为一种潮流,但这些行为既有成功也有失败。中国已就太空安全立场做了清晰的阐释。为避免误导与混淆,对太空安全一词,应考虑其使用场合,并做适当变通处理。

Mathematical Description of the Arming Process of a Fuze Safety System

By determining the state variables of a fuze safety system,some mathematical models——the system of ordinary differential and functional differential equations about the system's arming process are founded in a state space.Also,the arming states and restricted relations of the safety factors are described and some demonstrations are presented.

Partition airflow varying features of chaos-theory-based coalmine ventilation system and related safety forecasting and forewarning system

To realize real-time monitoring and short-term forecasting and forewarning of coalmine ventilation systems(CVS), in this paper, we first established a joint surface and underground CVS safety management system consisting of main ventilation fan, safety-partition linked passageways, and air-required locations. We then applied chaos theory to identify the air quantity and gas concentration of underground partition boundaries, and adopted a fixed data quantity, multi-step progressive, weighted first-order local-domain method to setup a chaos prediction model and a CVS safety forecasting and forewarning system formed by the normal change level, orange forewarning level, and red alarm level. We next conduct the on-field application of the system in a coalmine in Jining, Shandong, China. The results showed that (1) in the statistical scale of 5 min, the changes in both air quantity and gas concentration along CVS partition airflow boundaries were characteristic of chaos and could be used for short-term chaos prediction, and the latter was more chaotic than the former;(2) the setup chaos prediction model had a higher prediction precision and the established safety prediction system could not only predict the variation in CVS stability but also reflect the rationality of underground mining intensity. Thus, this CVS safety forecasting and forewarning system is of better application value.

UNITED STABILIZING SCHEME FOR EDGE DELAY IN OPTICAL BURST SWITCHED NETWORKS

A novel scheme, namely united stabilizing scheme for edge delay, is introduced in optical burst switched networks. In the scheme, the limits of burst length and assembly time are both set according to certain qualifications. For executing the scheme, the conception for unit input bit rate is introduced to improve universality, and the assembly algorithm with a buffer safety space under the self-similar traffic model at each ingress edge router is proposed. Then, the components of burst and packet delay are concluded, and the equations that limits of burst length and assembly time should satisfy to stabilize the burst edge delay under different buffer offered loads are educed. The simulation results show that united stabilizing scheme stabilizes both burst and packet edge delay to a great extent when buffer offered load changes from 0.1 to 1, and the edge delay of burst and packet are near the limit values under larger offered load, respectively.

An improved bicubic imaging fitting algorithm for 3D radar detection target

3D ground-penetrating radar has been widely used in urban road underground disease detection due to its nondestructive,efficient,and intuitive results.However,the 3D imaging of the underground target body presents the edge plate phenomenon due to the space between the 3D radar array antennas.Consequently,direct 3D imaging using detection results cannot reflect underground spatial distribution characteristics.Due to the wide-beam polarization of the ground-penetrating radar antenna,the emission of electromagnetic waves with a specific width decreases the strong middle energy on both sides gradually.Therefore,a bicubic high-precision 3D target body slice-imaging fitting algorithm with changing trend characteristics is constructed by combining the subsurface target characteristics with the changing spatial morphology trends.Using the wide-angle polarization antenna’s characteristics in the algorithm to build the trend factor between the measurement lines,the target body change trend and the edge detail portrayal achieve a 3D ground-penetrating radar-detection target high-precision fitting.Compared with other traditional fitting techniques,the fitting error is small.This paper conducts experiments and analyses on GpaMax 3D forward modeling and 3D ground-penetrating measured radar data.The experiments show that the improved bicubic fitting algorithm can eff ectively improve the accuracy of underground target slice imaging and the 3D ground-penetrating radar’s anomaly interpretation.

Evaluation of fire smoke control in underground space

The main goal of the fire management strategy is to avoid people interaction with fire hazards,therefore several studies are carried out for optimal escape route planning as well as smoke management and mechanical ventilation design.Underground spaces are a special case of study due to their technical characteristics that create different fire spread conditions compared to conventional buildings.In this paper,a comparative study on the fire smoke propagation is carried out taking into account the use and performance of smoke mitiga-tion techniques.The Underground Hazardous Waste Management Repository of Lavrion Technological and Cultural Park in Greece,is selected as a case study to achieve the paper objectives.A Computer Fluid Dynamic software is used to simulate various fire scenarios based on the specific characteristics of the underground space.Parameters that have significant impact on evacuation procedure and human health such as visibility and carbon monoxide concentration are monitored.Finally,the results are presented and an evaluation method is proposed based on evacuation simulation results,in order to predict the impact of the smoke control design on the conditions inside the underground space.The results reveal that the ventilation shaft(passive system)offers an effective smoke control without any other combined control system and that the installation of smoke curtains,which are activated on time,offers significant improvement on smoke spread control extending the available egress time(ASET)in case of fire.

Cooperative Lane-Change Maneuver for Multiple Automated Vehicles on a Highway

With the development of vehicle-to-vehicle(V2V)communication,it is possible to share information among multiple vehicles.However,the existing research on automated lane changes concentrates only on the single-vehicle lane change with self-detective information.Cooperative lane changes are still a new area with more complicated scenarios and can improve safety and lane-change efficiency.Therefore,a multi-vehicle cooperative automated lane-change maneuver based on V2V communication for scenarios of eight vehicles on three lanes was proposed.In these scenarios,same-direction and intersectant-direction cooperative lane changes were defined.The vehicle that made the cooperative decision obtained the information of surrounding vehicles that were used to cooperatively plan the trajectories,which was called cooperative trajectory planning.The cooperative safety spacing model was proposed to guarantee and improve the safety of all vehicles,and it essentially developed constraints for the trajectory-planning task.Trajectory planning was treated as an optimization problem with the objective of maximizing safety,comfort,and lane-change efficiency under the constraints of vehicle dynamics and the aforementioned safety spacing model.Trajectory tracking based on a model predictive control method was designed to minimize tracking errors and control increments.Finally,to verify the validity of the proposed maneuver,an integrated simulation platform combining MATLAB/Simulink with CarSim was established.Moreover,a hardware-in-the-loop test bench was performed for further verification.The results indicated that the proposed multi-vehicle cooperative automated lane-change maneuver can achieve lane changes of multiple vehicles and increase lane-change efficiency while guaranteeing safety and comfort.