中国西南四种常见松树火适应性状比较

野火对松属植物的进化和分布有重要的影响。在与野火长期抗争中,松属植物形成了一系列性状提高在易火生境中的适合度,维持种群生存与繁衍。西南地区是中国野火高发区,作为这一地区特有松树,云南松、思茅松和高山松具有一些典型的火适应性状,如厚树皮。以这3种松树和东部常见的马尾松为研究对象,比较4种松树的火适应对策。结果表明:4种松树的火适应性状存在一定的差异。与火适应相关的13项性状主成分分析显示,4个种在空间上总体是分离的,也表现出一些重叠。其中云南松火适应生活史对策是火耐受型和火依赖型的中间类型,适应会发生林冠火的生境。高山松、思茅松和马尾松都是火耐受型,通过快速高生长、厚树皮等性状适应生境不同频度的地表火。四种松树火适应对策与分布区火险基本相符。表明野火在这一区域广泛存在,并对植物进化和森林格局有重要影响。野火在西南地区松属分布和种群维持中的生态作用应被给予足够重视。

不同温度处理对疏序黄荆种子萌发的影响

以中国西南元谋干热河谷地区典型物种疏序黄荆(Vitex negundo L.f.laxipaniculata Pei)种子为实验材料,探究萌发前高温处理对种子萌发率的影响,探讨植物对火长期干扰的适应进化。结果表明,1)除100℃(5 min)和100℃(10 min)2种处理方式萌发率低于常温对照外,其余各组萌发率均高于常温对照组,萌发率在80℃(5 min)处理时最高,为(62.33±3.13)%,具有明显的热冲击效应;2)除100℃(5 min)和100℃(10 min)2种处理方式种子热冲击效应指数RI小于0外,其余各组均大于0,在80℃(5 min)时达到最大(0.3529),表明在一定温度范围内热冲击对疏序黄荆种子萌发具有促进作用;3)主效应方差分析表明,处理温度和时间长度对疏序黄荆种子的萌发率均有显著影响,其中温度(F=148.092,p<0.001)影响最大;4)萌发前的高温处理对种子活力也具有一定的影响,温度过高可能会破坏种子结构,影响其萌发;5)热冲击可以在一定范围内提高疏序黄荆种子的萌发势,加速种子萌发,且在80℃(5 min)时达到最大。研究表明,疏序黄荆种子具有明显的热冲击效应,且热冲击可提高其萌发势,缩短萌发所需时间。

栎类林对火的适应和响应研究进展

近年来,由于人类活动的影响,加之极端天气常现,森林火灾呈现持续多发且频发的趋势,火格局(发生季节、频率、强度等)也发生相应改变。尽管栎类林出现了各种不同频率和强度的火灾,但大多数栎类已经进化出能够在周期性火灾中生存的能力。需要明确栎类对森林火灾的响应,进而揭示栎类对火的适应性策略。本文从栎类林特征、燃烧性、栎类植物自然更新以及个体和种群对火干扰的适应与响应等方面入手,论述了栎类林对火的适应与响应,对其现存研究问题进行了分析,并对未来的研究方向进行了展望。研究结果能够为生态恢复树种选择、防火树种筛选、生物防火林带营建等提供科学依据,有利于我国栎类的适地适树造林和管护,特别有利于火灾频发多发区域选择抗火性强的栎类树种;有利于对栎类的分类经营和管理,提高生产力;有利于栎类的高效综合利用,发挥生态、经济和社会效益。

Application of adaptive Kalman filter in rocket impact point estimation

In order to measure the parameters of flight rocket by using radar,rocket impact point was estimated accurately for rocket trajectory correction.The Kalman filter with adaptive filter gain matrix was adopted.According to the particle trajectory model,the adaptive Kalman filter trajectory model was constructed for removing and filtering the outliers of the parameters during a section of flight detected by three-dimensional data radar and the rocket impact point was extrapolated.The results of numerical simulation show that the outliers and noise in trajectory measurement signal can be removed effectively by using the adaptive Kalman filter and the filter variance can converge in a short period of time.Based on the relation of filtering time and impact point estimation error,choosing the filtering time of 8-10 scan get the minimum estimation error of impact point.

Adaptive fault-tolerant control of heavy lift launch vehicle via differential algebraic observer

A novel adaptive fault-tolerant control scheme in the differential algebraic framework was proposed for attitude control of a heavy lift launch vehicle （HLLV）. By using purely mathematical transformations, the decoupled input-output representations of HLLV were derived, rendering three decoupled second-order systems, i.e., pitch, yaw and roll channels. Based on a new type of numerical differentiator, a differential algebraic observer （DAO） was proposed for estimating the system states and the generalized disturbances, including various disturbances and additive fault torques. Driven by DAOs, three improved proportional-integral- differential （PID） controllers with disturbance compensation were designed for pitch, yaw and roll control. All signals in the closed-loop system were guaranteed to be ultimately uniformly bounded by utilization of Lyapunov＇s indirect method. The convincing numerical simulations indicate that the proposed control scheme is successful in achieving high performance in the presence of parametric perturbations, external disturbances, noisy corruptions, and actuator faults.

Novel Adaptive Simulated Annealing Algorithm for Constrained Multi-Objective Optimization

In recent years, sinmlated annealing algo-rithms have been extensively developed and uti-lized to solve nmlti-objective optimization problems. In order to obtain better optimization perfonmnce, this paper proposes a Novel Adaptive Simulated Annealing （NASA） algorithm for constrained multi-objective optimization based on Archived Multi-objective Simulated Annealing （AMOSA）. For han-dling multi-objective, NASA makes improverrents in three aspects： sub-iteration search, sub-archive and adaptive search, which effectively strengthen the stability and efficiency of the algorithnm For handling constraints, NASA introduces corresponding solution acceptance criterion. Furtherrrore, NASA has also been applied to optimize TD-LTE network perform-ance by adjusting antenna paranleters; it can achieve better extension and convergence than AMOSA, NS-GAII and MOPSO. Analytical studies and simulations indicate that the proposed NASA algorithm can play an important role in improving multi-objective optimi-zation performance.

Dynamic characteristic analysis of whole machine tools based on Kriging model

In order to study the variation of machine tools’dynamic characteristics in the manufacturing space,a Kriging approximate model is proposed.Finite element method(FEM)is employed on the platform of ANSYS to establish finite element(FE)model with the dynamic characteristic of combined interface for a milling machine,which is newly designed for producing aero engine blades by a certain enterprise group in China.The stiffness and damping of combined interfaces are adjusted by using adaptive simulated annealing algorithm with the optimizing software of iSIGHT in the process of FE model update according to experimental modal analysis(EMA)results.The Kriging approximate model is established according to the finite element analysis results utilizing orthogonal design samples by taking into account of the range of configuration parameters.On the basis of the Kriging approximate model,the response surfaces between key response parameter and configuration parameters are obtained.The results indicate that configuration parameters have great effects on dynamic characteristics of machine tools,and the Kriging approximate model is an effective and rapid method for estimating dynamic characteristics of machine tools in the manufacturing space.

The Research on Key Technologies of Chinese Heavy-Lift Launch Vehicle Control System

This paper reviewed the development of control technology in domestic and foreign launch vehicle(LV), and based on which, the key technologies of control system for Chinese heavy-lift launch vehicles were proposed. A dynamic on-line trajectory planning technique was discussed to meet the demand of guidance control under complex constraints, and model based identification and adaptive control technology was suggested to deal with the control problems caused by model uncertainty and disturbance, and an integrated avionics system based on high speed communication was put forward for module integration and distributed control, and FBG based real time flight control was also discussed. Moreover, other key technologies, such as wireless interconnection, wireless power transfer, and temporal and spatial partitioning operating system, are both briefly introduced for the application in control systems. These studies will lead to breakthroughs in autonomous flight control in LV, and provide technical support for more long-term deep space explorations.

烟促种子萌发研究新进展

野火是全球陆地生态系统植被更新的重要驱动力,野火伴生的烟气含有多种活性化合物,可以促进火后植物的种子萌发。传统观点认为,烟气中普遍含有纤维素热解产生的Karrikin类物质,是促进火后种子萌发的主要烟信号化合物。最新研究发现,木质素热解产生的丁香醛也可以促进火后植物的种子萌发。本文综述了烟信号化合物的发现历程,阐释了烟信号化合物与植物火后更新的生态相关性,并对植物烟信号适应性的演化进行了探讨。在此基础上,本文提出了烟促种子萌发研究领域仍待解答的一些科学问题,并对本领域的未来研究方向进行了展望。

Delay-induced firing behavior and transitions in adaptive neuronal networks with two types of synapses

In this paper, we study delay-induced firing behavior and transitions in adaptive Newman-Watts networks of thermosensitive neurons with electrical or chemical synapses. It is found that electrical and chemical synapse time delay-induced firing behavior and transitions differ significantly. In the case of electrical synapses, the bursts for a fixed delay involve equal number of spikes in each burst, and for certain time delays the firing can be inhibited. However, in the case of chemical synapses the bursts for a fixed delay involve different numbers of spikes in each burst, and no firing inhibition is observed. It is also shown that larger growth rates of adaptive coupling strength or larger network randomness can enhance the synchronization of bursting in the case of electrical synapses but reduce it in the case of chemical synapses. These results show that electrical and chemical synapses have different effects on delay-induced firing behavior and dynamical evolution. Compared to electrical synapses, chemical synapses might be more beneficial to the generation of firing and abundant firing transitions in adaptive and delayed neuronal networks. These findings can help to better understand different firing behaviors in neuronal networks with electrical and chemical synapses.

Alignment control for a long span urban rail-transit cable-stayed bridge considering dynamic train loads

In this paper, bridge alignment control with considering dynamic train loads was experimentally and theoretically investigated.Analytical process of bridge dynamics and the self-adaptive Kalman filter bridge alignment control method with considering the dynamic train loads were briefly introduced. The static measurement, the dynamic test, the field alignment measurement as well as the finite element analysis(FEA) of the second longest rail transit cable-stayed bridge in the world were carried out.Based on the results, the train dynamic load effect on the bridge alignment was obtained quantitatively. Subsequently, alignment control of the rail transit bridge with considering this effect using a self-adaptive Kalman filter method was analyzed. The results show that:(a) the dynamic train loads have effects on alignment control of the bridge and therefore cannot be neglected;(b) the self-adaptive Kalman filter method is applicable and reliable for alignment control of bridges during construction. The analytical method and whole process contribute to develop a related specification and further engineering applications.