Scouts behave as streakers in honeybee swarms

Harmonic radar tracking was used to record the flights of scout bees during takeoff and initial flight path of two honeybee swarms. One swarm remained intact and performed a full flight to a destination beyond the range of the harmonic radar, while a second swarm disintegrated within the range of the radar and most of the bees returned to the queen. The initial stretch of the full flight is characterized by accelerating speed, whereas the disintegrating swarm flew steadily at low speed. The two scouts in the swarm displaying full flight performed characteristic flight maneuvers. They flew at high speed when traveling in the direction of their destination and slowed down or returned over short stretches at low speed. Scouts in the disintegrating swarm did not exhibit the same kind of characteristic flight performance. Our data support the streaker bee hypothesis proposing that scout bees guide the swarm by traveling at high speed in the direction of the new nest site for short stretches of flight and slowing down when reversing flight direction.     

一种提高飞行器结构天地力学环境地面试验有效性的方法及其应用

目的研究提高飞行器结构地面试验有效性的途径。方法计算同一被试件结构在飞行状态和地面试验状态下的有限元模型,测量地面试验状态下的模态以验证有限元模型的正确性;计算各特征点(也可以是遥测点)在天地状态下的响应,用机器学习法获取各特征点的映射关系模型;基于该模型由飞行点响应(或遥测数据)确定出地面试验件对应点的响应,并用载荷反求法得到它们的等效载荷;最终确定施加在试验系统上的载荷。结果以细长体结构为例,所得到由其组成试验系统的有限元模型与实测模型之间的固有频率最大相对误差为6.76%,利用映射关系模型预测出对应点在飞行状态下的振动响应。确定了飞行状态下结构响应的特征点,由地面试验系统所对应的响应点反推出应施加的载荷为60 N。结论利用天地数值计算-地面试验验证联合法,无需在地面试验状态下刻意模拟飞行状态的边界条件,确定出所需要施加的载荷,从而提高了飞行器地面试验的有效性。     

A juvenile coelurosaurian theropod from China indicates arboreal habits

Here we report an unequivocal arboreal coelurosaur, Epidendrosaurus ningchengensis gen. et sp. nov. This juvenile coelurosaur's third manual digit is extremely elongated, distinctively different from that of other known dinosaurs and birds. It represents certainly a type of adaptation previously unreported from the Mesozoic although the exact function of the third manual digit is unclear. The relatively long forelimb, penultimate phalanx of manual digit II, and pedal penultimate phalanges, are interpreted as evidence for the arboreal habit of Epidendrosaurus. Because Epidendrosaurus is more similar to advanced birds in some arboreal features than to Archaeopteryx, we suggest that the initial appearance of tree-adaptation in theropods was probably not directly related to flight but to other functions, such as seeking food or escaping from predators. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00114-002-0353-8. On that page (frame on the left side), a link takes you directly to the supplementary material.     

再入飞行振动环境试验等效性探讨

目的提高再入体实验室模拟再入飞行振动环境的等效性,确保地面环境试验结果的可靠性。方法首先分析再入飞行过程中受脉动压力等因素影响诱发的振动环境载荷特征。其次,基于飞行实测数据,分析再入飞行振动响应的空间分布规律和频域能量分布特征。最后,将飞行试验实测数据与传统实验室振动模拟试验结果进行对比,从载荷传递规律、空间分布规律、频谱特征等方面对主要关注区域"天地"响应存在的差异进行探讨,研究实验室等效模拟再入飞行振动环境的因素。结果针对特定的再入体结构,设置有限等效响应目标点,通过对试验系统动态特性分析、夹具优化设计、试验控制方式、振动台激振模式等多方面综合研究,可以提升再入飞行振动环境模拟等效性。结论提出了以"天地一致性"为目标的工程可行措施和实验室振动试验等效原则,为再入飞行振动环境的实验室等效模拟提供了支撑。     

单机寿命监控中飞行时间的确定方法及影响研究

对飞机实际的飞行时间判断正确与否将直接影响到对飞机损伤量的计算。对两种飞行时间确定方法进行了对比,分析表明,通过发动机转速同时结合地速为判断准则,可以更为准确地从飞行参数数据中提取飞行时间。评估了8种机型损伤量的计算结果,对比表明,对于经常使用加力状态起飞的飞机或起降性能一般的飞机来说,飞行时间上的变化会对损伤量的计算值产生较大影响。     

Statistical comparison of the AGDISP model with deposit data

An aerial spray Agricultural Dispersal (AGDISP) model was tested against quantitative field data. The microbial pesticide Bacillus thuringiensis (Bt) was sprayed as fine spray from a helicopted over a flat site in various meteorological conditions. Droplet deposition on evenly spaced Kromekote cards, 0.15 m above the ground, was measured with image analysis equipment. Six complete data sets out of the 12 trials were selected for data comparison. A set of statistical parameters suggested by the American Meteorological Society and other authors was applied for comparisons of the model prediction with the ground deposit data. The results indicated that AGDISP tended to overpredict the average volume deposition by a factor of two. The sensitivity test of the AGDISP model to the input wind direction showed that the model may not be sensitive to variations in wind direction within 10 degrees relative to aircraft flight path.     

民航飞机起飞过程气态污染物排放特征分析

民航飞机在起飞过程中发动机推力高、耗油量大,并且飞行高度低,由其排放的污染物对局地空气质量和人体健康存在较大影响.选择B737-800作为典型机型,通过对飞机性能参数的模拟,精确计算了其在全推力和减推力等多种方式下起飞离场爬升至1 000 m高度过程中NO_x、CO、HC和SO_2的排放量,并与ICAO基准模型估算结果进行对比.结果表明,NO_x是排放量最大的污染物.其中,全推力起飞过程4种污染物的排放量分别为4.849、0.062、0.031和0.229 kg.减推力起飞方式下,选择更高的灵活温度后,NO_x和CO排放量分别降低和升高,HC和SO2排放量变化不大.经过对比发现,ICAO的基准排放模型,对4种污染物的估算结果存在较大偏差.与机动车相比,单次全推力起飞过程与一辆小客车行驶9 508 km的NO_x排放量相当.精确计算方法为准确估算机场区域飞机污染排放清单提供基础.     

基于实测数据的空空导弹自由飞振动条件制定方法研究

目的基于实测数据来分析和研究空空导弹自由飞振动环境,讨论并建议空空导弹自由飞振动试验条件制定方法。方法针对空空导弹振动数据的特殊性对数据进行处理分析。结果实测数据处理得到空空导弹每个区域的振动响应谱,通过地面试验和动力学仿真分析修订得出地面试验谱。结论要制定一个合理的空空导弹自由飞振动试验条件,必须基于实测数据进行处理分析,并建立在适当的振动实施条件下。     

高超声速钝锥等离子体鞘套电波传播特性研究

目的改进现阶段地面指控站对临近空间高超声速飞行器的通信和测控效果。方法采用计算流体动力学技术模拟钝锥体在不同高超声速飞行条件下的头身部绕流流场特性,并运用相关公式建立钝锥等离子体鞘套电磁模型。然后运用改进的移位算子时域有限差分方法计算电磁波经过等离子体鞘套的传播特性。结果计算结果表明,电磁波在等离子体鞘套内的传播特性在频率处于最大等离子体频率附近时发生转折,电磁波通过等离子体鞘套的透射效果与飞行工况和入射波条件密切相关。相对其他入射角度,当电磁波垂直于飞行体物面入射到等离子体鞘套尾部时的电磁波衰减较小。飞行高度增加或飞行速度减小时,等离子体鞘套对电磁波的衰减效应将减弱。结论该研究可为有效测控临近空间高超声速飞行器、缓解再入通讯中断现象提供一定的技术突破方法。     

一种基于综合环境剖面的导弹弹上设备加速贮存试验方法

目的 基于导弹武器在历经地面使用载荷后,还要满足飞行载荷的特点,讨论用于评估导弹弹上设备贮存期的加速贮存试验流程与方法。方法 开展加速因子试验,获得加速因子计算公式,根据实际使用环境载荷,制定综合环境试验剖面,按照贮存期目标值开展加速贮存试验,等效地面使用环境载荷,开展飞行环境载荷考核试验,试验成功后,给出贮存期评估结论。结果 该方法在多型导弹贮存延寿工程的弹上设备贮存期评估中得到应用,应用表明,可以评估导弹弹上设备的贮存期,具有工程应用价值。结论 获得加速因子计算公式后,将导弹弹上设备的地面使用环境载荷累计影响与能够经受飞行载荷环境分步进行试验,能够体现导弹弹上设备历经的环境载荷,可以用于弹上设备的贮存期评估。     

<Emphasis Type="Bold">Chronodisruption and cancer</Emphasis>

Research into health effects of chronodisruption (CD), a relevant disturbance of the circadian organization of physiology, endocrinology, metabolism and behaviour, is evolving at a rapid pace. With regard to malignancies, our synthesis of key experiments indicates that CD can play a causal role for cancer growth and tumor progression in animals. Moreover, our meta-analyses of 30 epidemiological studies evince that flight personnel and shift workers exposed to chronodisruption may have increased breast and prostate cancer risks: summary relative risks (RRs) for investigations of flight personnel and of shift workers suggested a 70 and 40% increase in the risk of breast cancer, respectively, and excess relative risks of prostate cancer in nine studies in flight personnel (40%) and in two studies in male shift workers. There was a remarkable indication of homogeneity of results from the individual studies that contribute to the average statistics. However, in view of doubts about whether the differing assessments of CD can really be regarded as valid reflections of the same causative phenomenon and the lack of control of covariates in the majority of studies, it is premature to conclude that the risk observations reflect a real, rather than spurious, association with CD. The challenge for future epidemiological investigations of the biologically plausible links between chronodisruption and human cancers is to conduct studies which appreciate details of transmeridian travelling, of shift work and of covariates for the development of the diseases.     

Behavioural correlates of urbanisation in the Cape ground squirrel Xerus inauris

Urbanisation critically threatens biodiversity because of habitat destruction and novel selection pressures. Some animals can respond to these challenges by modifying their behaviour, particularly anti-predator behaviour, allowing them to persist in heavily transformed urban areas. We investigated whether the anti-predator behaviour of the Cape ground squirrel Xerus inauris differed in three localities that differed in their level of urbanisation. According to the habituation hypothesis, we predicted that ground squirrels in urban areas would: (a) be less vigilant and forage more; (b) trade-off flight/vigilance in favour of foraging; and (c) have shorter flight initiation distances (FID) when approached by a human observer. Observations were made in winter and summer at each locality. As expected, ground squirrels in urbanised areas were less vigilant and had shorter FIDs but did not trade-off between foraging and vigilance. In contrast, a population in a non-urbanised locality showed greater levels of vigilance, FID and traded-off vigilance and foraging. A population in a peri-urban locality showed mixed responses. Our results indicate that Cape ground squirrels reduce their anti-predator behaviour in urban areas and demonstrate a flexible behavioural response to urbanisation.     

Diel flight behaviour and dispersal patterns of aquatic Coleoptera and Heteroptera species with special emphasis on the importance of seasons

Dispersal flight is the most important and almost the only way for primary aquatic insects to find new water habitats. During a 30-week-long project, we monitored the flight dispersal behaviour of aquatic beetles and bugs with using highly and horizontally polarizing agricultural black plastic sheets laid onto the ground. Based on the flight data of more than 45,000 individuals and 92 species, we explored and described eight different diel flight activity patterns. We found that seven of eight dispersal patterns are consistent with the previous knowledge, while three conspicuous mass dispersal periods can be identified as in the mid morning and/or around noon and/or at nightfall. As an exception, we found a ‘daytime’ pattern occurred exclusively in spring, in which mass dispersal can be seen from mid morning to late afternoon. In contrast to previous studies, we emphasize here that the seasonality has to be considered in evaluation of the diurnal flight activity. According to the seasons, a ‘three code sign’ was proposed to indicate the diel dispersal flight behaviour of a species for a year. Most of the species utilize different diel activity patterns in different seasons. In spring, the daytime pattern was the preferred type, but in summer and autumn, the evening types were the most popular patterns. We stated that the seasonal change of air temperature has a crucial role in that a pattern could be manifested in a given season or not and brings a need to change the diel dispersal pattern among seasons.     

再入环境测量火箭测试平台总体设计与关键技术

目的研究弹头再入飞行时表面的脉动压力等参数特征及变化规律,借助火箭测试平台飞行试验,同步获取自由飞行状态下载荷段外部脉动压力、时均压力、温度与内部结构振动、冲击响应数据,认识和预测脉动压力载荷与结构响应的相关性,同时为结构响应等效的数值模拟验证提供支撑。方法根据飞行试验测试的目的和要求,计算火箭测试平台的总体参数和设计系统组成,开展总体设计技术、测试系统设计技术、防热设计技术、气动弹道设计技术等关键技术研究。结果设计了再入环境测量火箭测试平台,并完成了地面试验验证,用于开展飞行试验,获取典型再入环境下的气动力热数据、弹道参数和结构响应数据。结论通过地面试验,验证了再入环境测量火箭测试平台总体设计的正确性和系列关键技术的有效性。     

再入飞行器振动环境工程预示方法

目的为再入飞行器振动环境设计提供方法支撑,并为结构设计和地面环境试验条件制定提供载荷输入。方法分析再入飞行器振动环境主要特征及其诱导因素,结合飞行试验实测振动数据研究小攻角对飞行振动环境的影响规律,辨识出脉动压力与动压、马赫数以及攻角的关系式。在传统脉动压力预测方法基础上,建立涉及攻角影响的再入飞行均方根脉动压力预测模型,并给出再入振动环境工程预示方法。结果构建模型计算的脉动压力变化趋势与实测振动量值变化趋势基本一致,辨识出来的脉动压力与攻角、动压以及马赫数之间的关系式是基本合理的。结论基于实测数据及脉动压力特性建立了再入飞行器振动环境工程预示模型,结合实测振动数据和气动载荷数据可预测出再入飞行器振动环境,能够实现再入飞行器振动环境载荷的精细化设计,并为结构设计提供载荷输入。     

基于弹性模型的飞机操纵动响应分析

目的 更好地研究飞机在操纵情况下的机体载荷和机体响应,同时验证动态响应分析模型和方法。方法 以某型飞机突风载荷分析用的动气弹仿真模型为基础,考虑机体弹性修正和气动模型修正,梳理试验试飞的舵偏数据,利用MSC软件的动气弹仿真分析模块,将试飞的舵偏数据作为输入信号,开展舵面操纵情况下的机体响应仿真,并将飞机操纵情况下的机体响应分析结果与试验试飞结果进行对比。结果 经过仿真和对比分析可以发现,分析数据和试飞数据整体吻合较好,能够较好地表征飞机的气动特性和结构动力学特性,同时在分析数据和试飞数据中均有比较明显的机体弹性响应成分。对于弹性飞机而言,除操纵造成的机体刚体响应外,机体弹性会带来额外的振动响应,对于特定的部位,这种振动可能是不可忽略的,需要根据具体情况进行详细分析。结论 这种振动响应对飞机操纵、乘客舒适性是否会产生不利影响,需要进一步开展研究工作。     

基于实际飞行数据的首都机场飞机发动机日排放清单估算方法研究

根据航班实际飞行数据估算机场飞机主发动机排放量,可以提升机场排放清单编制的准确度.基于北京首都机场某日运行数据和国内1326架次航班的机载飞行数据(QAR数据),研究了基于飞行数据的机场飞机主发动机排放清单制定方法.采用一阶近似3.0(FOA3.0)方法补充国际民航组织发动机排放数据库颗粒物基准排放指数,结合QAR数据,应用波音燃油流量法2(BFFM2)估算了实际飞行条件下污染物排放指数,编制了首都机场该日飞机主发动机排放清单,分析了首都机场航班排放特征.在此基础上,探讨了结合实际数据本地化的着陆和起飞循环,以期为机场飞机主发动机排放量的快速准确核算提供新的思路.结果发现,该日航班主发动机HC、CO、NO_x和PM_(2.5)排放量分别为933.9、10967.8、14703.5和85.5 kg,较标准LTO循环估算结果的偏差分别为15.6%、13.2%、-29.1%和-18.9%.NO_x排放主要集中在起飞和爬升阶段,占其排放总量的68.0%;HC和CO排放主要集中在滑行和慢车阶段,分别占其排放总量的90.0%和88.0%;PM_(2.5)在各飞行阶段的排放较为平均.对于单位LTO循环,航班滑行过程中平均排队等候(地速为零)时间为7.7 min,产生的HC、CO、NO_x和PM_(2.5)分别占总滑行阶段对应污染物排放量的26.3%、27.5%、25.7%和27.5%,这一部分排放量有望通过场面运行优化进一步控制.     

飞机飞行振动预计技术研究

介绍了飞机飞行振动的主要来源和特征,分析了传统预计方法的不足,针对飞机飞行振动与高度、马赫数和攻角等飞行参数呈非线性关系的特点,提出了基于BP神经网络的飞行振动预计新技术,建立了预计模型,通过8组建模样本训练网络,确定了预计模型中的各个参数值。预计结果和实测飞机飞行振动信号比较分析表明,该方法预计精度高,验证了BP神经网络预计飞机飞行振动的可行性。     

基于任务剖面的机载外挂温度试验条件探讨

目的获取一种合理的温度试验条件用以考核机载外挂对温度环境的适应性。方法针对影响机载外挂温度的自然或诱发环境因素,分别分析自然环境、气动加热以及设备工作发热的三种典型因素的不同特点,并结合机载外挂的空中挂飞使用状态,给出相应的温度计算方法。结果通过对某载机的典型任务剖面的计算,指出了现有机载外挂基于地面使用温度制定的试验条件无法完全覆盖空中挂飞时的温度环境,并由此提出了基于任务剖面的温度试验条件,以更好地考核机载外挂温度环境适应性。结论给出了一种用于考核机载外挂温度环境适应性的温度试验条件及其计算方法。     

结合QAR数据的全航段排放估算及其对飞行成本的影响研究

随着排放对环境的影响日趋严重,排放成本被纳入飞行总成本的趋势已成为必然.在对基础飞行成本模型进行改进过程中,为了准确计算飞机排放量,依据机载QAR（Quick Access Recorder,快速存取记录器）数据中表征发动机实际运行的诸多参数,准确获取排放量,进而利用改进飞行总成本模型计算实际飞行成本.同时,讨论了燃油成本、时间成本及排放成本在综合成本中所占的比例.结果表明,燃油成本占比最大,约为41.63%;时间成本约占34.13%,排放成本占比达到24.24%,超过燃油成本的1/2.由此可见,排放成本对总成本影响很大,其影响不可忽视,多方面考虑计算排放量及排放成本,可为航空公司初步评估飞机运行成本提供有效依据.