Individual consistency in spatiotemporal characteristics of migratory Whimbrels in the East Asian-Australasian Flyway

Many migratory birds exhibit interannual consistency in migration schedules,routes and stopover sites.Detecting the interannual consistency in spatiotemporal characteristics helps understand the maintenance of migration and enables the implementation of targeted conservation measures.We tracked the migration of Whimbrel(Numenius phaeopus)in the East Asian-Australasian Flyway and collected spatiotemporal data from individuals that were tracked for at least two years.Wilcoxon non-parametric tests were used to compare the interannual variations in the dates of departure from and arrival at breeding/nonbreeding sites,and the inter-annual variation in the longitudes when the same individual across the same latitudes.Whimbrels exhibited a high degree of consistency in the use of breeding,nonbreeding,and stopover sites between years.The variation of arrival dates at nonbreeding sites was significantly larger than that of the departure dates from nonbreeding and breeding sites.Repeatedly used stopover sites by the same individuals in multiple years were concentrated in the Yellow Sea coast during northward migration,but were more widespread during southward migration.The stopover duration at repeatedly used sites was significantly longer than that at sites used only once.When flying across the Yellow Sea,Whimbrels breeding in Sakha(Yakutia)exhibited the highest consistency in migration routes in both autumn and spring.Moreover,the consistency in migration routes of Yakutia breeding birds was generally higher than that of birds breeding in Chukotka.Our results suggest that the northward migration schedule of the Whimbrels is mainly controlled by endogenous factors,while the southward migration schedule is less affected by endogenous factors.The repeated use of stopover sites in the Yellow Sea coast suggests this region is important for the migration of Whimbrel,and thus has high conservation value.

Hierarchical and Distributed Optimal Control Strategy for Power and Power Quality of Microgrid Based on Finite-Time Consistency

Droop control is one of the main control strategies of islanded microgrid(MG),but the droop control cannot achieve reasonable power distribution of microgrid,resulting in frequency and voltage deviation from the rating value,which needs the upper control link to eliminate the deviation.However,at present,most layered control requires a centralized control center,which excessively relies on microgrid central controller(MGCC)and real-time communication among distributed generation(DG),which has certain limitations.To solve the above problems,this paper proposes a hierarchical distributed power and power quality optimization strategy based on multi-agent finite time consistency algorithm(MA-FTCA).Firstly,based on the first layer droop control,MA-FTCA is applied to introduce frequency and voltage compensation to stabilize the system frequency and voltage at the rated value.Secondly,in the third layer,the MA-FTCA is adopted to estimate the total active power and total reactive power spare capacity of the system,to realize the reasonable distribution of active power and reactive power output of each DG according to its proportion of spare capacity when the system load side changes.The control strategy proposed in this paper adopts a completely distributed control method and does not need a centralized control center in each layer of control.Finally,MATLAB/Simulink simulation platform is used to verify the correctness and effectiveness of the proposed optimization strategy.

ENTROPY CONSISTENCY OF LARGE TIME STEP SCHEMES FOR ISENTROPIC EQUATIONS OF GAS DYNAMICS

In this paper, We show for isentropic equations of gas dynamics with adiabatic exponent gamma=3 that approximations of weak solutions generated by large time step Godunov's scheme or Glimm's scheme give entropy solution in the limit if Courant number is less than or equal to 1.

Photodissociation Dynamics of 2-1odotoluene Investigated by Femtosecond Time-Resolved Mass Spectrometry

The photodissociation dynamics of 2-iodotoluene following excitation at 266 nm have been investigated employing femtosecond time-resolved mass spectrometry. The photofragments are detected by multiphoton ionization using an intense laser field centered at 800 nm. A dissociation time of 3804-50 fs was measured from the rising time of the co-fragments of toluene radical （C7H7） and iodine atom （I）, which is attributed to the averaged time needed for the C-I bond breaking for the simultaneously excited nσ and ππ＊ states by 266 nm pump light. In addition, a probe light centered at 298.23 nm corresponding to resonance wavelength of ground-state iodine atom is used to selectively ionize ground-state iodine atoms generated from the dissociation of initially populated hσ＊ and ππ＊ states. And a rise time of 4004-50 fs is extracted from the fitting of time-dependent I＋ transient, which is in agreement with the dissociation time obtained by multiphoton ionization with 800 nm, suggesting that the main dissociative products are ground-state iodine atoms.

湿基α-半水石膏制备高强石膏制品研究

为实现湿基α-半水石膏制备高强石膏制品,研究了湿基α-半水石膏陈化时间、粉磨时间、浇筑料浆温度及缓凝剂掺量等工艺参数对高强石膏凝结时间和强度的影响,并确定最佳制备工艺。此外,采用X射线衍射、扫描电子显微镜等微观测试手段,揭示了各因素对强度的影响机理。结果表明:陈化时间越长,石膏凝结时间越短,制品强度越低;随着粉磨时间延长,石膏凝结时间显著缩短,制品强度先升高后降低;料浆温度越高,石膏凝结时间越长,制品强度越低。最佳制备工艺:陈化时间5 min、粉磨时间20 s、料浆温度20℃。在此基础上加入0.08%(质量分数)缓凝剂能够有效地延长石膏凝结时间并提高硬化强度,制备的石膏制品性能优异,绝干抗折强度为14.1 MPa,绝干抗压强度为58.3 MPa。微观测试结果表明,各工艺参数会通过改变石膏标稠用水量和水化进程来影响石膏内部结构的密实程度和二水石膏晶体的生长发育,最终影响制品硬化强度。

Impact of time lags on diurnal estimates of canopy transpiration and canopy conductance from sap-flow measurements of Populus cathayana in the Qinghai–Tibetan Plateau

Recently, canopy transpiration （Ec） has been often estimated by xylem sap-flow measurements. However, there is a significant time lag between sap flow measured at the base of the stem and canopy transpiration due to the capacitive exchange between the transpiration stream and stem water storage. Significant errors will be introduced in canopy conductance （gc） and canopy transpiration estimation if the time lag is neglected. In this study, a cross-correlation analysis was used to quantify the time lag, and the sap flowbased transpiration was measured to pararneterize Jarvistype models of gc and thus to simulate Ec of Populus cathayana using the Penman-Monteith equation. The results indicate that solar radiation （Rs） and vapor pressure deficit （VPD） are not fully coincident with sap flow and have an obvious lag effect; the sap flow lags behind Rs and precedes VPD, and there is a 1-h time shift between Eo and sap flow in the 30-min interval data set. A parameterized Jarvis-type gc model is suitable to predict P. cathayana transpiration and explains more than 80% of the variation observed in go, and the relative error was less than 25%, which shows a preferable simulation effect. The root mean square error （RMSEs） between the predicted and measured Ec were 1.91×10^-3 （with the time lag） and 3.12×10^-3cm h^-1 （without the time lag）. More importantly, Ec simulation precision that incorporates time lag is improved by 6% compared to the results without the time lag, with the mean relative error （MRE） of only 8.32% and the mean absolute error （MAE） of 1.48 × 10^-3 cm h^-1.

Real-time crash prediction on freeways using data mining and emerging techniques

Recent advances in intelligent transportation system allow traffic safety studies to extend from historic data-based analyses to real-time applications. The study presents a new method to predict crash likelihood with traffic data collected by discrete loop detectors as well as the web-crawl weather data. Matched case-control method and support vector machines （SVMs） technique were employed to identify the risk status. The adaptive synthetic over-sampling technique was applied to solve the imbalanced dataset issues. Random forest technique was applied to select the contributing factors and avoid the over-fitting issues. The results indicate that the SVMs classifier could successfully classify 76.32% of the crashes on the test dataset and 87.52% of the crashes on the overall dataset, which were relatively satisfactory compared with the results of the previous studies. Compared with the SVMs classifier without the data, the SVMs classifier with the web-crawl weather data increased the crash prediction accuracy by 1.32% and decreased the false alarm rate by 1.72%, showing the potential value of the massive web weather data. Mean impact value method was employed to evaluate the variable effects, and the results are identical with the results of most of previous studies. The emerging technique based on the discrete traffic data and web weather data proves to be more applicable on real- time safety management on freeways.

A Numerical Algorithm Based on Quadratic Finite Element for Two-Dimensional Nonlinear Time Fractional Thermal Diffusion Model

In this article,a high-order scheme,which is formulated by combining the quadratic finite element method in space with a second-order time discrete scheme,is developed for looking for the numerical solution of a two-dimensional nonlinear time fractional thermal diffusion model.The time Caputo fractional derivative is approximated by using the L2-1formula,the first-order derivative and nonlinear term are discretized by some second-order approximation formulas,and the quadratic finite element is used to approximate the spatial direction.The error accuracy O(h3+
t2)is obtained,which is verified by the numerical results.

Modeling and Control of Time-pressure Dispensing for Semiconductor Manufacturing

To improve the consistency of the adhesive amount dispensed by the time-pressure dispenser for semiconductor manufacturing, a non-Newtonian fluid flow rate model is developed to represent and estimate the adhesive amount dispensed in each cycle. Taking account of gas compressibility, an intelligent model-based control strategy is proposed to compensate the deviation of adhesive amount dispensed from the desired one. Both simulations and experiments show that the dispensing consistency is greatly improved by using the model-based control strategy developed in this paper.

Quorum systems for intrusion-tolerance based on trusted timely computing base

Quorum systems have been used to solve the problem of data consistency in distributed fault-tolerance systems. But when intrusions occur, traditional quorum systems have some disadvantages. For example, synchronous quorum systems are subject to DOS attacks, while asynchronous quorum systems need a larger system size （at least 3f＋1 for generic data, and f fewer for self-verifying data）. In order to solve the problems above, an intrusion-tolerance quorum system （ITQS） of hybrid time model based on trust timely computing base is presented （TTCB）. The TTCB is a trust secure real-time component inside the server with a well defined interface and separated from the operation system. It is in the synchronous communication environment while the application layer in the server deals with read-write requests and executes update-copy protocols asynchronously. The architectural hybridization of synchrony and asynchrony can achieve the data consistency and availability correctly. We also build two kinds of ITQSes based on TTCB, i.e., the symmetrical and the asymmetrical TTCB quorum systems. In the performance evaluations, we show that TTCB quorum systems are of smaller size, lower load and higher availability.

A probability-consistent method based on practical ground surface motion

In this paper, a new method for seismic hazard analysis, the probability-consistent method based on practical ground surface motion is proposed. Time histories on ground surface in the method correspond to earthquakes occurring at potential sources around sites. So of the envelope parameter, response spectrum, peak ground acceleration are of physical sense. Neglecting the response of site soil layers, the method is the same as routine probability-consistent method. The natural seismic acceleration time histories can be used for input wave directly. Generating ground motion is an approximation under lack of data of strong motion. Along with accumulating of the strong motion data around sites, we can describe the seismic environment more objectively.

Thermodynamic Consistency and Thermomechanical Dynamics (TMD) for Nonequilibrium Irreversible Mechanism of Heat Engines

The irreversible mechanism of heat engines is studied in terms of thermodynamic consistency and thermomechanical dynamics (TMD) which is proposed for a method to study nonequilibrium irreversible thermodynamic systems. As an example, a water drinking bird (DB) known as one of the heat engines is specifically examined. The DB system suffices a rigorous experimental device for the theory of nonequilibrium irreversible thermodynamics. The DB nonlinear equation of motion proves explicitly that nonlinear differential equations with time-dependent coefficients must be classified as independent equations different from those of constant coefficients. The solutions of nonlinear differential equations with time-dependent coefficients can express emergent phenomena: nonequilibrium irreversible states. The couplings among mechanics, thermodynamics and time-evolution to nonequilibrium irreversible state are defined when the internal energy, thermodynamic work, temperature and entropy are integrated as a spontaneous thermodynamic process in the DB system. The physical meanings of the time-dependent entropy, T(t)dS(t), , internal energy, dƐ(t), and thermodynamic work, dW(t), are defined by the progress of time-dependent Gibbs relation to thermodynamic equilibrium. The thermomechanical dynamics (TMD) approach constitutes a method for the nonequilibrium irreversible thermodynamics and transport processes.

Stackelberg微分博弈下的鲁棒最优投资-再保险问题

考虑一个以模糊厌恶再保险公司为领导者,模糊中立保险公司为追随者的Stackelberg随机微分博弈问题.通过求解拓展的HJB(Hamilton-Jacobi-Bellman)方程组,给出时间一致性均值-方差准则下的鲁棒最优投资-再保险策略以及相应的值函数.最后,通过数值例子和敏感性分析说明最优策略与主要参数之间的关系.

具有实际约束的多阶段M-V投资组合时间一致性策略研究

从动态规划的角度分析,方差算子的不可分离性导致标准的多阶段均值-方差模型的最优投资策略不满足时间一致性。文章采用条件期望映射的方法,构建了一个具有交易成本、借贷约束和阈值约束的多阶段M-V投资组合模型。由于考虑了交易成本,该模型是一个具有路径依赖性的动态优化问题。为了获得其时间一致性投资策略,文章将该问题近似地转化为连续性动态规划模型,证明最优解的近似度,并运用离散迭代算法求解。最后,使用上海证券交易所的部分历史数据验证了模型和算法的有效性。

Suppressive Influence of Time- Space White Noise on the Explosion of Solutions of Stochastic Fokker- Planck Delay Differential Equations

It is generally known that the solutions of deterministic and stochastic differential equations （SDEs） usually grow linearly at such a rate that they may become unbounded after a small lapse of time and may eventually blow up or explode in finite time. If the drift and diffusion functions are globally Lipschitz, linear growth may still be experienced, as well as a possible blow-up of solutions in finite time. In this paper, a nonlinear scalar delay differential equation with a constant time lag is perturbed by a multiplicative Ito-type time - space white noise to form a stochastic Fokker-Planck delay differential equation. It is established that no explosion is possible in the presence of any intrinsically slow time - space white noise of Ito - type as manifested in the resulting stochastic Fokker- Planck delay differential equation. Time - space white noise has a role to play since the solution of the classical nonlinear equation without it still exhibits explosion.

带落角约束的新型领弹-从弹固定时间协同制导律

针对多导弹以期望角度协同攻击机动目标问题,提出了一种新型领弹-从弹固定时间协同制导律。根据弹目相对运动关系建立了领弹-从弹协同制导模型;基于固定时间滑模控制理论设计了视线法向上的制导律,实现了领弹和从弹以期望的攻击角度对机动目标进行精准打击。在从弹视线方向上,基于一致性误差函数和固定时间滑模趋近律,设计了一种从弹视线方向制导律,充分利用了导弹间的信息交互,实现了从弹与领弹的剩余时间在固定时间内快速趋于一致。数值仿真和对比试验结果表明:所提制导律对时间协同和角度约束的控制精度高,避免了奇异和抖振现象,收敛速度快且收敛时间上界与初始状态无关,充分地验证了所提制导律的有效性和优越性。

房地产调控政策的有效性分析--基于动态一致性

近几年,中国对房地产市场实施了一系列的宏观调控政策,但效果却不容乐观。本文从政策动态一致性的视角,对房地产调控政策的有效性进行了研究。首先简要介绍了动态一致性理论的主要内容和动态不一致产生的原因;然后,对我国房地产市场的发展历程和调控政策进行了回顾,并分析了我国房地产调控政策动态不一致的原因;最后,指出为提高房地产调控政策有效性,应制定兼具规则与灵活性的政策、建立政府良好声誉、协调中央与地方政府关系,还要充分考虑公众反应。

光纤探针诊断100kA-LTD模块开关的同步性

设计了一套用于同轴多间隙气体开关导通起始时间诊断的光纤探针阵列测试系统,其由光纤阵列与多通道快响应光电转换仪两部分组成,系统同步时间小于1ns。使用该套系统同时对100kA-LTD模块所有并联支路的10只开关的放电过程进行了测试,获得了开关导通起始时间及模块的输出电流波形。实验结果表明:开关工作欠压比为85%时,时间抖动不超过6.9ns,负载波形重复一致性较好;开关工作欠压比降至53%时,时间抖动急剧增加至117.7ns,负载波形重复一致性显著恶化。同时将光纤测试系统获得的各个开关导通起始时间带入Pspice电路模型进行模拟反演,结果表明,模拟结果与实验得到的模块输出电流波形吻合较好,证明了测试系统的准确性。

水泥-石灰石粉浆体流变经时行为研究

研究了水泥-石灰石粉浆体流变参数随水化时间的变化,采取RHEORIAB QC型旋转黏度计测定水泥-石灰石粉浆体流变,采用Herschel-Bulkley模型拟合浆体曲线得到相关流变参数,分别利用Roussel和Philippe提出的模型对水泥-石灰石粉浆体的动态屈服应力和稠度进行拟合。结果表明:水泥浆体动态屈服应力比石灰石粉浆体小,稠度比石灰石粉浆体大;水泥-石灰石粉浆体动态屈服应力、稠度随水化时间线性增大,随石灰石粉掺量增加,增大速率线性减小,其初始动态屈服应力线性增大,初始稠度按二次抛物线先增大后减小。