Cyclical helping hands: seasonal tailwinds differentially affect migrating Oriental Storks (Ciconia boyciana) travel speed

Background:The Oriental Stork(Ciconia boyciana)breeds in southeastern Siberia and parts of northeast China,and winters mainly in southeast China.Although the autumn migration pattern of Oriental Storks has been previ-ously described,differences between spring and autumn migration travel speed in relation to wind assistance were unknown.Methods:Using GPS/GSM transmitters,we tracked the full migrations of 18 Oriental Storks during 2015-2018 to compare differences in autumn and spring migration patterns,and combined the satellite telemetry data with the National Center for Environmental Prediction Reanalysis data to explain the relationship between 850 mbar wind vec-tors and seasonal differences in travel speed.Results:Differences in tailwinds contributed to significant differences in daily average Oriental Storks travel speed in spring(258.11±64.8 km/day)compared to autumn(172.23±49.7 km/day,p<0.001).Storks stopped significantly more often in autumn than spring(1.78±1.1 versus 1.06±0.9,p<0.05),but stopover duration(15.52±12.4 versus 16.30±15.1 days,respectively,p=0.3)did not differ significantly.Tailwinds at 850 mbar pressure level(extracted from the National Center of Environmental Prediction Reanalysis data archive)significantly affected daily flying speed dur-ing spring and autumn migration.Tailwind conditions in spring(mean 4.40±5.6 m/s)were always more favourable than in autumn when they received no net benefit(0.48±5.6 m/s,p<0.001).Despite mean spring migration dura-tion being less than autumn(27.52±15.9 versus 32.77±13.4 days,p=0.17),large individual variation meant that this duration did not differ significantly from each other.Conclusions:For long distance migratory soaring birds(such as storks),relative duration of spring and autumn migration likely relates to the interaction between imperative for earliest arrival to breeding grounds and seasonal meteorological conditions experienced en route.

Floating Car Data Based Nonparametric Regression Model for Short-Term Travel Speed Prediction

A K-nearest neighbor （K-NN） based nonparametric regression model was proposed to predict travel speed for Beijing expressway. By using the historical traffic data collected from the detectors in Beijing expressways, a specically designed database was developed via the processes including data filtering, wavelet analysis and clustering. The relativity based weighted Euclidean distance was used as the distance metric to identify the K groups of nearest data series. Then, a K-NN nonparametric regression model was built to predict the average travel speeds up to 6 min into the future. Several randomly selected travel speed data series, collected from the floating car data （FCD） system, were used to validate the model. The results indicate that using the FCD, the model can predict average travel speeds with an accuracy of above 90%, and hence is feasible and effective.

Effect of travel speed on seed spacing uniformity of corn seed meter

Both seeding performance of seed metering unit and travel speed of seed planter have significant effects on seeding quality,thereby affecting crop growth and yields.In order to determine the effects of different travel speeds on seed spacing uniformity,four different types of seed meters were evaluated at five different travel speeds on seed meter test bench and in field.The tested seed meters included a finger pickup seed meter,a scoop-wheel seed meter,an air-pressure type seed meter and an air-blowing type seed meter.The seeding performance of the horizontal distribution of seeds within a row was described by using the coefficient of variation,the quality of feed index,the multiple index and the miss-seeding index.Experiments were performed in laboratory and field,respectively.Results indicated that different travel speeds have statistically significant effects on seed spacing uniformity.The four types of seed meters performed better on the seed meter test bench than in the field.Coefficient of variation increases and quality of feed index decreases as the travel speed of seed planter increases.The best seed spacing uniformity was obtained with the air-pressure type seed meter,followed with the air-blowing type seed meter,the finger pickup seed meter and the scoop-wheel seed meter.There were considerable differences between the performances of the scoop-wheel seed meter in the bench test and field test;the seeding qualities were much better in the bench test than in the field test.The scoop-wheel seed meter is more sensitive to vibration than the other types of seed meters.

Sowing uniformity of bed-type pneumatic maize planter at various seedbed preparation levels and machine travel speeds

Precision planters are important machines in the regime of modern technological agriculture.Field conditions,seed metering system and machine operating parameters affect the pneumatic planter performance.The pneumatic planter was evaluated to determine the effect of three tillage levels(L1,L2,and L3)and four travel speeds(S1,S2,S3 and S4).The sowing uniformity of the planter was observed with respect to the horizontal distribution of seeds within a row and described by using the precision index(Ip),the multiple index(Imult),the miss-seeding index(Imiss)and the quality of feed index(Iqf).The results revealed that the tillage levels(L)and travel speed(S)had a significant effect(p<0.05)on dependent variables.The maximum Imiss(22.12%)was observed at L1 and S4 whereas the maximum Imult was observed at L1 and S1.The mean values of missing-,multi-,quality-feed and precision indices were 5.14%,5.833%,89.03%and 17.85%at L3,respectively.The mean values of multi-index 17.59%,14.44%,12.40%and 10.18%,quality feed index 74.07%,75.92%,75.74%and 74.07%and precision indices 21.47%,23.26%,25.51%and 28.53%were at S1,S2,S3 and S4,respectively.The study showed that maize could be seeding within an acceptable precise range by bed-type pneumatic planter subjected to the proper seedbed preparation level.

An estimation of vehicle kilometer traveled and on-road emissions using the traffic volume and travel speed on road links in Incheon City

The objective of this study is to estimate the vehicle kilometer traveled（VKT） and on-road emissions using the traffic volume in urban. We estimated two VKT; one is based on registered vehicles and the other is based on traffic volumes. VKT for registered vehicles was 2.11 times greater than that of the applied traffic volumes because each VKT estimation method is different. Therefore, we had to define the inner VKT is moved VKT inner in urban to compare two values. Also, we focused on freight modes because these are discharged much air pollutant emissions. From analysis results, we found middle and large trucks registered in other regions traveled to target city in order to carry freight, target city has included many industrial and logistics areas. Freight is transferred through the harbors,large logistics centers, or via locations before being moved to the final destination. During this process, most freight is moved by middle and large trucks, and trailers rather than small trucks for freight import and export. Therefore, these trucks from other areas are inflow more than registered vehicles. Most emissions from diesel trucks had been overestimated in comparison to VKT from applied traffic volumes in target city. From these findings, VKT is essential based on traffic volume and travel speed on road links in order to estimate accurately the emissions of diesel trucks in target city. Our findings support the estimation of the effect of on-road emissions on urban air quality in Korea.

How fast is it to city centers?The average travel speed as an indicator of road traffic accessibility potential

Transportation is the lifeblood of a modern metropolis.Accessibility generally refers to the interconnection between nodes in a regional traffic network.The purpose of the paper is to obtain more realistic and accurate measures of travel speed and to study the road traffic accessibility potential in cities.This study proposes a method for analyzing road traffic accessibility potential which is based on the average travel speed to city centers in off-peak times and which ranks 80 cities around the world.Based on the Suomi National Polar-Orbiting Partnership satellite’s visible-infrared imaging radiometer suite(NPP-VIIRS)night-time light data,urban built-up areas and city centers were extracted.Further,with the aid of the Google Maps application programming interface(API)network crawling technique,travel times and travel distances for several optimal routes to city centers by car were obtained.Feasible proposals for improving road traffic accessibility and planning urban transportation in different cities are presented.The proposed method offers a new possibility of analyzing traffic accessibility using internet data and geo-spatial methods.

CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

Stability and a fast calculation method of travel speed of pulse peak in convergence zone

A long-range sound propagation experiment was conducted in the West Pacific Ocean in summer 2013.The signals received by a towed array indicate that the travel speed of pulse peak(TSPP)in the convergence zones is stable.Therefore,an equivalent sound speed can be used at all ranges in the convergence zones.A fast calculation method based on the beam-displace-ment ray-mode(BDRM)theory and convergence zone theory is proposed to calculate this equivalent sound speed.The computation speed of this proposed method is over 1000 times faster than that of the conventional calculation method based on the normal mode theory,with the computation error less than 0.4%compared with the experimental result.Also,the effect of frequency and sound speed profile on the TSPP is studied with the conventional and fast calculation methods,showing that the TSPP is almost independent of the frequency and sound speed profile in the ocean surface layer.

REMARK ON CRITICAL SPEED OF TRAVELING WAVEFRONTS FOR NICHOLSON'S BLOWFLIES EQUATION WITH DIFFUSION

This note is devoted to the son＇s blowflies equation with diffusion, a critical speed of traveling waves, we give behavior with respect to the mature age study on the traveling wavefronts to the Nicholtime-delayed reaction-diffusion equation. For the a detailed analysis on its location and asymptotic

Influence of the Domain Boundary on the Speeds of Traveling Waves

Let H > 0 be a constant, g ≥ 0 be a periodic function and Ω ={(x, y) ||x| H + g (y), y ∈R}. We consider a curvature flow equation V = κ + A in Ω, where for a simple curve γt Ω, V denotes its normal velocity, κ denotes its curvature and A > 0 is a constant. [1] proved that this equation has a periodic traveling wave U, and that the average speed c of U is increasing in A and H, decreasing in max g' when the scale of g is sufficiently small. In this paper we study the dependence of c on A, H, max g' and on the period of g when the scale of g is large. We show that similar results as [1] hold in certain weak sense.

城市轨道交通网络系统效率评价指标改进

为提高城市轨道交通网络系统效率评价指标的可比性和完备性,引入有效行程速度和有效客流密度的概念,改进了网络系统效率评价指标,并以重庆市中心城区2017年和2019年运营的城市轨道交通线网为例验证了改进后评价指标的科学性和可操作性。研究表明:既有评价指标由于显著受到线网服务范围的影响,且未体现网络的投入产出效率,无法直接作为网络结构优化的目标函数;改进后的系统效率评价指标能够综合反映剔除线网服务范围影响后的网络结构性能和投入产出效率,且存在理论上的最优值;平衡网络中节点换乘时间和路段行程时间,并适度加密城市核心区域的轨道交通线路和站点,是持续提升网络系统效率的2个重要手段。

站城融合理念下高铁站点换乘导视系统优化设计研究

目的本文以重庆建设国际性综合交通枢纽城市为研究背景,满足各类人群高铁出行的适宜性与多样性需求,升级城市形象展示窗口。深入剖析高铁站点导视系统在换乘枢纽中的实际应用情况,紧密关注城市智慧交通导视系统的发展趋势与最新动态,致力于解决用户在换乘过程中可能遇到的视觉困扰和引导不足等核心问题,并在此基础上提出具有针对性的优化设计方案。方法对城市高铁站轨道换乘导视系统的设计要点和布设方法进行举证研究,重点就城市智慧出行、数字导视系统进行分析,结合对乘客空间寻路、安全感、舒适感等心理需求的调研,总结轨道交通换乘站点导视系统的设计思路。综合考虑色彩及应用、字号及对比度、字体及视觉度、布设逻辑与信息分级,把控导视系统的视觉度、布设尺度、色彩材质、技术工艺。结合我国高铁站轨道换乘导视系统的发展现状,提出重庆西站换乘导视系统的优化设计策略。结论在尊重空间动向、用户体验、视觉流程的基础上,以智慧交通导视系统为研究对象,充分探寻高铁站点轨道换乘导视系统的高效性、便捷性,旨在提升枢纽的建设水平、运行效率,以及人民群众的出行体验。

数理统计分析算法下智能插秧机作业优化研究

以智能插秧机驱动电机功率分配与参数优化为研究对象,通过试验验证的方式获取电动插秧机作业过程中不同载荷和不同行进速度条件下的牵引力大小数据,并采用数理统计分析算法得出牵引力平均数据。根据插秧机分插机构和方形机构的作业功率需求,对电动插秧机的功率分布进行分析,同时确定各机构的驱动电机与插秧机整体电源需求功率,进一步对插秧机的作业参数进行优化。采用试验的方式获取电动插秧机在不同载荷和不同行进速度条件下的最大作业面积数据,通过数理统计分析算法原理得出插秧机最大作业面积均值数据。试验结果表明:当插秧机行进速度为0.5m/s时,可以获得最大连续作业面积。

高速铁路旅客智慧出行服务数据体系研究

新一代信息技术的发展给出行方式带来了巨大变化,旅客对出行服务提出了更高的要求。智慧出行服务有望利用数据信息分析与处理技术提升服务质量,但目前还存在数据标准不一、数据治理平台尚无、数据共享困难等难题。以高速铁路旅客服务为中心,贯穿出行前与售后、枢纽乘降与接驳和列车在途3个阶段,梳理旅客出行全过程的相关数据;以出行数据全生命周期管理为主线,从数据汇集、存储、治理、共享、应用与安全6个方面,设计高速铁路旅客智慧出行服务数据体系框架,并提出高速铁路旅客出行服务数据标准体系的建设思路,以期发挥高速铁路旅客智慧出行数据体系的数据价值,为智慧出行服务和运营管理发展提供理论依据。

高速挖掘机涉水条件下的机动能力仿真与评估

高速挖掘机的机动性能是装备遂行工程保障行动效率的重要指标之一,涉水条件是高速挖掘机在机动过程中经常遇到的自然条件,结合这一常见环境影响因素,基于实装数据,构建装备仿真模型,分析涉水条件下的动力学模型.以高速挖掘机的最高行驶速度和加速能力两个方面为例,开展高速挖掘机涉水条件下的机动性能仿真与评估研究,计算得到不同涉水深度和不同水流流速条件下的加速时间、最高行驶速度,能够为科学研判高速挖掘机的相关机动性能提供理论参考,为高速挖掘机使用单位提供借鉴指导.

基于双端行波频率变化特性的中低速磁浮交通供电轨故障定位方法

中低速磁浮供电轨供电过程中容易发生直流接地故障,由于其供电距离较短、接地网结构复杂,发生直流接地故障后不易准确定位故障点。为此针对以上问题,根据列车运行过程中车体与轨道无接触的特点,建立中低速磁浮牵引供电系统,分析双端故障测距与单端故障测距的优缺点,研究供电轨发生接地故障后故障行波时域分布与频域分布的关系;并通过计算式计算分析行波频谱的产生机理,得出故障行波的频率分布不受车站内阻抗、过渡电阻的影响,只与故障点位置和故障行波到达线路两端的时间相关;基于此,提出基于双端频率变化特性的中低速磁浮交通供电轨故障定位方法,根据故障行波频率特性与行波速度计算故障点位置。并且通过仿真验证,该方法不受故障点位置、过渡电阻大小影响,且适用于单处接地故障、多处接地故障类型,故障误差始终保持在1%以内,相比传统的直流牵引供电系统故障定位方法,测量精度更高,适用于中低速磁浮交通供电轨接地故障。

超高速快轴旋转圆形弹光调制技术研究

针对目前广义椭偏测量速度受限问题,提出利用对称性更优的圆形弹光调制器代替机械旋转补偿器实现超高速测量。对弹光调制器内部受力进行理论研究,得到纯行波模式调制条件并利用COMSOL仿真验证。仿真结果表明,当弹光调制器处于纯行波调制模式时可视为一种快轴方向高速旋转的相位调制器。通过建立阻尼弦振动模型分析不同快轴方向下弹光晶体表面振动位移分布,提出一种弹光调制器在纯行波调制模式下的中心支撑方式用于实验。实验结果表明弹光调制器的快轴以f/2的角速率做圆周运动。同时验证了中心支撑方式可确保弹光调制器谐振后所受阻力均匀且最小,达到最佳支撑效果。研究结果可用于后续广义椭偏测量及各类高速偏振调制领域。

100 kHz弹光调制器多功能调制仿真

针对弹光调制器(photoelastic modulator,PEM)在超高速全偏振领域的测量问题,研究一种目标频率在100 kHz附近的圆型PEM,由弹光晶体和2个方位角相差45°的压电驱动器组成。通过理论计算弹光晶体谐振频率和压电驱动器振动频率,当二者频率达到一致时,PEM工作在谐振状态,此时PEM的调制效率达到最高。当PEM达到谐振状态并趋于稳定后,调节两压电驱动器驱动电压的幅值与相位,实现纯驻波模式和纯行波模式两种特殊调制,纯驻波模式可实现纯电控制下调制快轴的延迟量和方位角;纯行波模式可实现纯电控制下调制快轴以PEM谐振频率的半频速度高速旋转。最后,利用COMSOL有限元仿真模拟两种调制模式下PEM,验证两种调制状态下的PEM振型及其快轴方向,表明PEM可实现多功能弹光调制,为后续偏振测量提供理论支撑。

车辆行驶方向与参照物存在夹角时车速计算方法研究

在运用GA/T 1133--2014《基于视频图像的车辆行驶速度技术鉴定》标准推荐的视频车速计算方法中,目标车辆的行驶轨迹被设定为一种理想状态(车辆与参照物为垂直姿态),然而,方法中并未所选取的特征点到车辆纵向平面的距离不相等时车速计算的方法,以及目标车辆行驶方向与参照物之间存在夹角的问题。在计算视频车速时,如果所选取的特征点到车辆纵向平面的距离不相等,和(或)目标车辆的行驶方向和参照物之间存在角度时,考虑角度变化与忽略角度计算结果存在明显差值。为了能够准确、客观地计算出车辆的实际车速,针对所选取的特征点到车辆纵向平面的距离不相等和(或)行驶方向和参照物之间存在夹角的情况,提出了三种解决办法。