The orbital elements of space objects provide collision warning and can be used to adjust the launch window of satellites, space stations and spacecraft. The observation of low earth orbit (LEO) objects are mainly carried out using ground-based radars. The effectiveness of space observation radar can be reflected by the ability of new object discovery, observation efficiency, the accuracy of measurement and orbit determination, the quality of radar imaging, and the recognition rate. Specifically, the higher the number of space objects with determined parameters observed in the same time, the higher is the observation efficiency of radar.

本平台拟采用以JAVA语言结合SQL数据库进行开发，主要分为前台设计、后台模块管理及数据库设计等。在开发过程中，应该以图书馆的馆藏资源为主要服务依托，通过cookies脚本程序与国内的豆瓣网、卓越亚马逊网、Google Books等网站链接，便于读者浏览相关的书评，以达到加强阅读推广效果的目的。

It turns out to be an optimization problem to improve the performance of space observation on the constraint of radar resources. There are many previous studies on radar resources management for multiple target detection. G. Van Keuk[1] and Yinfei Fu[2] studied task scheduling for ground-based phased array radar and wireless sensor networks respectively; to select the subset of jobs to be processed during the given planning period and determining the starting time and scan-off angle for each selected job, M.R. Taner[3] studied the problem of scheduling the searching, verification, and tracking tasks of a ground-based three-dimensional military surveillance radar. They scheduled tasks to realize radar resource optimization for common targets, while the issue of observing more targets to improve efficiency was not considered. For space objects, the priori orbital elements can be utilized for observation and tracking, and further optimization can be implemented by prearrangement of observation order. Zhongchao Xu[4] scheduled the space objects according to requirement and equipment constraint to improve the observation efficiency of facilities, without utilizing orbital elements. Hua Liang[5] made simulations on observation objects arrangement using prior orbital elements, while the actual constraints and realizability of facilities were not considered.

Phased array radars with the characteristics of beam agility track multiple objects seamlessly, while the mechanical scan radar has a single beam, and its antenna servo system has the characteristic of inertia. Therefore, for a ground- based mechanical scanning radar, it is necessary to arrange multiple objects observation scheduling reasonably, considering the requirement of observation rate. While the observation scheduling is optimized, the number of observation objects can be maximized during a period of observation time, and a high precision performance for orbit determination can be achieved.

This letter presents an observation scheduling algorithm for multiple objects based on semi-random search. The observation scheduling is screened by a designed fitness function. Additionally the connection time pair (CTP) and the tracks between two objects are determined for mechanical scanning radar. The multiple target observation is equivalent to long-time single target observation, so highly efficient observation is obtained. The scheme of scheduling optimization is shown in Fig.1.

Fig.1 Scheme of scheduling optimization

1 Optimization of the Initial Observation Scheduling Based on Semi-random Search

The visibility of each object should be determined first for an object set to be observed.We define “observation session” as a period of continuous operating time of radar and “observation bin” as a fraction of time. Observation bin is the increment of time to assign observation tasks. Observation session can be uniformly divided into a series of successive observation bins.

Initial observation scheduling is generated by simulations.Fig. 2 shows the simulation results of 7 objects.

Designate an object for each observation bin utilizing a random search method and considering the constraints on multiple objects observations. This random search with constraints is called a semi-random search. Initial observation scheduling can so be obtained by using semi-random search. The constraints here mainly refer to observation strategy. The factors include the observation rate (observing L revolutions during M days), object priority and minimum or maximum observation time per revolution or arc. Observation rate is determined by the principle of orbital altitude stratification, importance of objects and the requirement of orbit determination accuracy or radar imaging resolutions[8]. Object priority is set according to observation requirement, the more important the objects are, the higher their priority.For mechanical scanning radar, the servo system constraints should also be considered, which include the elevation range of the antenna, its angular velocity range and angular acceleration range in azimuth and elevation.

“Highest Priority First” and “Earliest Deadline First” are the two main strategies proposed to generate initial observation scheduling by this semi-random search method. “Highest Priority First” refers to the condition that low-priority objects can be selected only after all the high-priority objects are successfully observed. The priority of one object will be adjusted to minimum if its observation rate requirement has been met. Select one object randomly if several objects have the same priority. “Earliest Deadline First” specifies that the object whose observation time expires the earliest should be selected first. The so-called “expired time” is the last time the moment in which the object could be observed in the current revolution.

本研究建立了一种准确、简便的测定心肌组织中ATP等能量代谢物质的含量的方法，但其仅直接测定各组别心肌组织中各种能量物质的含量，由于几种能量代谢物质之间转化过程及其机制尚不明确，对于个别能量指标变化尚不能完全解释，比如，ATP、AMP、PCr同时增加，难以完全支持“ATP的生成需消耗ADP、AMP使其含量减少”这一单纯的理论推测，尚需进一步深入研究或结合整体动物实验中其他指标综合考虑。

In this paper, GA is applied to optimize CTP by adjusting time increment.N initial observation scheduling lead to N observation scheduling optimized. A final observation scheduling can be determined according to experimental requirement and the value of each element in fitness function. Some factors are required to be considered in the fitness function. The maximum of each factor is 1 for the convenience of weighting.

比阴柔审美更可怕的是“精神娘气”，缺铁缺钙，失去阳刚，羸弱无力。人们重视阴柔审美的问题，希望荧屏硬朗一点，其实也是担心阳刚之气成为新一代身上的稀缺品。要解决这个问题，不仅需要荧屏作出努力，家庭、学校和社会都要重视这个问题，让我们的孩子“保持着元气淋漓的气象”（梁启超语）。

Referred to space object parameters provided by satellite situation report (SSR) and two-line element (TLE)[6], the visible object set can then be obtained by analyzing the constraints such as relative position between radar and objects, transmitting power and visual angle. Range, azimuth and elevation (RAE) of all visible objects can be calculated using the simplified general perturbations (SGP4) model[7], and then the visible objects in each observation bin can be obtained.

这样根据幼儿的年龄特点，从时间、空间上进行具体、周密的设计和安排，既可以错开时间有效利用场地，使之发挥最高使用率和最好使用效果，又可以避免相互的影响，确保幼儿开展活动有时间、有场地、有器材、有成效；同时丰富有趣的晨间体育锻炼活动，慢慢的也改变了个别孩子入园习惯，不仅充分保证了幼儿每天充足的户外活动时间，而且增加了幼儿的活动密度，确保幼儿在锻炼中身体得到良好发育，增强体质，全面提升幼儿的各项综合素质，促进其对外界环境的适应能力。

Fig.2 Schematic of observation scheduling generation

The entire scheduling process of multiple objects is completed when all the tracks of antenna beam steering are determined.Finally, the RAE time sequence comprising multiple objects can be obtained, and it can be used as the guidance for the radar observation.

2 Optimization of CTP Based on GA and Track Design for Mechanical Scanning

For the mechanical scanning radar, further optimization is needed due to its inertia of the servo system. The realizability of connection between two objects should be paid attention to. CTP between two adjacent objects in observation order can be optimized using GA, and the tracks in the spare time are designed, following which the seamless observation for multiple targets can be achieved.

The observation on TDM mode for multiple objects is shown in Fig.3. Tob is the minimum observation time of each object; Tsp is the spare time without target observation; t′e,i is the end of observation zone of object i, t′s,i+1 is the beginning of observation zone of object i+1. The end time of object i, denoted as A, can be set anywhere with t′e,i. The start time of object i+1, denoted as B, can be set anywhere within t′s,i+1. {A,B} is defined as TCP. Ti is the track of attenna beam from object i to object i+1.

1.2.3 性状测定方法 在油菜成熟准备收割前，对B、C、D、E 4个地块中倒伏情况进行统计。油菜成熟收割时，每个处理中随机选出3株油菜，使用卷尺、游标卡尺、量角器等工具测量其株高、茎粗、分枝角度、冠幅等多个性状，做好原始数据记载。

Fig.3 Observation on TDM mode for multiple objects

GA is an optimization algorithm imitating natural selection and genetic mechanism[9].Genetic algorithm with its evolution mutation strategy has strong global search capability[11]. It operates selection operator, crossover operator and mutation operator on initial population generated randomly. The optimal or local optimal solution can be obtained according to the appropriate fitness function. The selection operator combines the means of best individual preservation and fitness proportionate selection[10]. Crossover operator is a manner of two-point crossover, the cross position randomly generated must be located at the end area of an observation arc. Time increment is mutated by mutation operator at a certain probability to ensure its diversification.

For mechanical scanning radar, the strategy “Frontier First” should be considered.This refers to the condition that the next neighboring object which becomes present along the scan of antenna beam steering is selected. In this way the burden of antenna servo is reduced. If several objects are the frontier objects, we select one object randomly.

从覆盖广度来看，分类监管能够促使村镇银行整体的不合规贷款规模下降、合规贷款规模上升，而在现有的制度约束下，合规贷款大部分投向农户和小微企业。从覆盖深度来看，覆盖深度不仅取决于贷款规模，还取决于贷款的客户数，在分类监管的政策框架之下，监管部门虽然能够监管村镇银行的贷款投向及风险状况，但是无法监管村镇银行是否将贷款投向农户及小微企业中更为富裕的群体。由此，我们得出结论3:分类监管激励了村镇银行向农户及小微企业的贷款规模上升，拓宽了村镇银行服务的覆盖广度，但并不一定能够加深村镇银行服务的覆盖深度。

Observation interval：17/12/2013 0:00:00-8:20:00; international number of objects： 01616,04331,22652,22692,23787,27560,27868,32955; time of observation bin is 10 s; number of bins forward search cross：10; time of mean observation span： 6h; priority of each object is 1; observation rate M,L(observe L times during M days)=(1,1).

2.1 Efficiency factors

For mechanical scanning radar, the observation scheduling could be used for multiple target seamless observation only if the azimuth and elevation information of beam in spare time are appended in. Therefore, after the final observation scheduling is determined, the tracks of antenna beam should be designed according to the constraints of the servo system. The track is expressed in Fig.3. The principles of kinematics should be obeyed here. Rotational angular velocity and acceleration should be as small as possible to get smoothed track when motion displacement and spare time are fixed.

② Object observation ratio: β=Nob/Nt, where Nob is the number of objects observed, Nt is the total number of objects during observation session.

③The average displacement of antenna steering in the spare time Tsp:

is the average Euclidean distance of azimuth and elevation between the beginning of next arc and the end of current arc, Narc is the total number of arcs observed. is the max distance of azimuth and elevation of the beam during observation.

在实际调查分析研究期间可以发现，各区域与各层次调查学生具有的困难具有较大差距，在遇到问题时学生不知道使用怎样的方法与思路对问题进行分析与思考，若根据实际需求对动点问题进行分类与总结，可使学生在问题解答期间具有较为良好的思路。其中函数动点问题可分为三种类型分别为：与反比例函数结合、与一次函数结合以及与二次函数结合，其中与各种函数知识进行结合都可在题干与图中发现相应的信息。同时，也需要学生对函数的表达式、图形以及性质等具有较为良好的了解与掌握。

2.2 Performance factors

① The normalized variance of observation time for each arc: λ=1/(1+varw), where varw=var (Tarc) is the variance of observation time for each arc.

② The normalized average signal to noise ratio where S(·) is sigmoid function; is the average rSNR of all objects.

Orbit accuracy requirements, image quality and image resolution requirements can be expressed by performance elements.

2.3 Equipment consumption factor

① The normalized times of beam direction reentrant: ρ=Ma/Mm, where Ma is the reentrant time of beam steering trend for observing another object, Mm is the maximum time.

So the fitness function is

(1)

where q1,q2,…,q6 are the weighting coefficients and set by experience.

For each new individual generated, it is verified that the constraints are satisfied in the genetic process. The optimization procedure of CTP using GA is shown in Fig.4.

Fig.4 Optimization procedure of CTP

①Effective observation time ratio: α=Tob/Tos , where the observation time of all objects, Tos is the observation session.

1.3 观察指标 尿失禁评价指标：鼓励患者建立排尿日记，记录患者治疗前以及治疗后3～7 d的平均每日自愿排尿次数、每日SUI次数，并统计发生尿失禁的患者比例[7]。

In Fig. 2, ordinate object1…object7 are the objects mentioned above, and the black blocks represent that the objects are visual to radar.Ordinate observation scheduling 1 and observation scheduling 2 are the results of observation scheduling generation, and the object to be observed corresponding to each observation bin is arranged.

3 Outdoor Experiment and Performance Evaluation

3.1 Overview of the outdoor experiment

The outdoor experiment was carried out on December 17, 2013 using an S-band high-precision observation and measurement radar. This mechanical scanning radar is armed with a Cassegrain antenna and operated on data guidance mode in the experiment. The latest TLE and SSR are adopted.

In the experiment, in order to keep the antenna from being damaged when tracking multiple objects automatically, some parameters value of servo system were reduced by 0.9 times, such as azimuth angular velocity/angular acceleration and elevation angular velocity/angular acceleration. The parameters of antenna servo system are shown in Tab.1.

机器人辅助的腹腔镜前列腺癌根治手术因采用极端的头低脚高体位会造成眼内压升高，升高幅度随手术时间延长和呼气末CO2分压升高而加重，并伴随眼灌注压的进行性下降；患者恢复平卧位后眼内压力会迅速降低[33]。虽然目前因极度头低脚高位而造成的眼部并发症很罕见，但这种并发症风险是存在的；而且一旦发生将是灾难性的[34]。最近的一项随机对照研究显示：与30°头低脚高位相比，25°体位明显降低了眼内压升高幅度，且并未增加手术难度[35]。在一项荟萃分析中，丙泊酚静脉麻醉可能有助于减轻因头低位引起的眼内压升高[21]。

Tab.1 Parameters of antenna servo system

Azimuthrange/(°)Azimuthrangeensuringaccuracy/(°)Maximumangularvelocityofazimuth/((°)·s-1)Azimuthangularvelocityrangeensuringaccuracy/((°)·s-1)Maximumangularaccelerationofazimuth/((°)·s-2)Azimuthangularaccelerationrangeensuringaccuracy/((°)·s-2)0-3600-3607.20.02-60.720.4Elevationrange/(°)Elevationrangeensuringaccuracy/(°)Maximumangularvelocityofelevation/((°)·s-1)Elevationangularvelocityrangeensuringaccuracy/((°)·s-1)Maximumangularaccelerationofelevation/((°)·s-2)Elevationangularaccelerationrangeensuringaccuracy/((°)·s-2)-1-18110-603.60.02-30.360.2

The experiment was performed with number of objects which could be observed 559, observation session 08:00-10:00,minimum observation time per arc 30 s, observation time range per revolution [180,600] s, observation bin 30 s,observation rate {M,L}={2,2}, times of genetic iteration 200,species size 21,maximum ratio of optimal individual 0.92,mutation probability 0.005, the weighting coefficients in fitness function {q1,q2,q3,q4,q5,q6}={2,3,1,1,1,1}. Here, observation rate and the maximum ratio of optimal individual are set by Engineering requirements for space objects observation;times of genetic iteration is determined by experiments, while the times of genetic iteration is over 200, the optimization results will not be better, considering time spent and optimization results, the times of genetic iteration is set 200; mutation probability is set by engineering experience; weighting coefficients are set by experience and engineering requirements, for example, q1 is effective observation time ratio, the more important the objects are, the q1 is bigger; q3 is the average displacement of antenna steering in the spare time, considering the servo system, q3 should not be taken too big, or the servo system will be damaged easily.

2.持续提升巡视干部业务能力。从纪委、组织、审计和财务等单位抽调年富力强、经验丰富的干部，充实巡视组。以提高政策把握、调查研究、文字综合等能力为重点，加强对巡视干部的教育培训。有计划、有针对性地强化巡视干部学习教育，不断强化政治理论素养和业务工作能力，切实提升做好巡视工作的本领。

3.2 Results of the experiment

The effective observation time are 81.48 min within 120 min. 78 objects are expected to be observed in the optimized scheduling, and they were all observed successfully in the experiment. The number of times of antenna direction reentrant Ma is 52. As an example, the RAE time sequence of 3 objects observed in a 2 min interval is shown in Tab.2. And the statistics of scheduling results of outdoor experiments are shown in Tab.3.

Tab.2 Scheduling results (08:00:00-10:00:00)

ObjectNORADNo.TimeR/kmA/(°)E/(°)08:00:021632.620212.645024.74011165…………08:00:411832.180207.150020.10008:00:42—206.968019.980N/A(Tsp)…………08:01:29—178.841013.31008:01:302421.260178.834013.24020104…………08:02:042633.590178.512010.270

3.3 Performance evaluation

78 objects were observed within 120 min, which means the observation efficiency of this mechanical scanning radar is over 10 times higher than that of scanning radar before. The minimum observation time is 20 s and the minimum antenna latency time is 15 s, more than 30 objects can be observed within one hour. The effective tracking time ratio is close to 70%, which means the spare time is lower than one third. If the minimum observation time is 20 s, the maximum observation time is 60 s and the minimum antenna latency time is 15 s. 30 objects could be observed within 30 minutes, and the radar could observe one object in one minute.

Tab.3 Statistics of scheduling results of outdoor experiments

ItemsValueStarttime12/17/20138:00:00Endtime12/17/201310:00:00TotalnumberofobjectsNt559NumberofobjectsobservedNob78ObjecttrackingratioRtrack0.140TimesofantennadirectionreentrantMa52Totalobservationtime/min81.48EffectivetrackingtimeratioRt0.679Theaverageobservationtime/min1.045

It is verified by more experiments that the expected performance can be obtained by adjusting the weighting factors of the fitness function and other parameters. However, the weighting factors of the fitness function can be optimized by using Greedy algorithm to make the fitness function achieve the maximum in the future.

4 Conclusion

A scheduling optimization algorithm for multi-target observation based on TDM is proposed using priori orbital information of objects. The optimized observation scheduling is obtained by a semi-random search and fitness function screening when using phased array radar. For a mechanical scanning radar, the CTP between objects is optimized via GA and the tracks of antenna beam in the spare time are designed additionally. The issue of scheduling optimization of space object observations by radar was validated during anoutdoor experiment. The experiment results showed that the observation efficiency of the mechanical scanning radar has improved significantly. An important observation here is that if the number of measured targets was big enough and the observation time of each object was shorter, the effective utilization of observation time would be higher. Different optimization results can be obtained by adjusting parameters (like the weighting of coefficients of the fitness function) for different demands such as orbit determination and imaging.

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