机场航班延误优化模型

针对空中交通日益严重的航班延误,给出了一种机场航班延误优化模型.模型将机场的到达和出发视为密切相关的两个过程,考虑了具有连续航程的航班(到达和出发均由同一架飞机在当天顺序执行)及其到达和出发过程之间的相互影响.模型还充分考虑了机场容量、需求以及天气等因素的动态特性,在达到和出发过程之间实现流量分配的协同决策.在机场延误不可避免的情况下,该模型可以为管制员提供未来一段时间内的流量分配优化方案,尽量降低延误的后续影响.最后,结合中国某国际机场的实际数据,利用遗传算法对模型进行了验证,取得了很好的效果.     

空中交通流量管理中的多机场地面等待策略

为解决航班延误问题,提出了一种考虑机场网络的延误累加效应及连续航程航班影响的多机场空中交通流量管理模型。该模型采用地面等待策略,对机场网络中各机场的延误情况进行综合考虑。当某些机场容量受恶劣天气或其他突发情况影响发生变化,使延误无法避免时,能够合理分配机场的出发和到达容量,减少航班的空中延误。结合中国3个枢纽机场的流量数据,对模型进行了仿真计算。仿真结果表明:该模型提供了一种更安全、更经济的航班调度策略,可为民航相关部门制定航班计划提供辅助的战略决策。     

基于元胞传输理论的航空器进场优化模型

随着空中交通流量的增长航班延误问题日益严重,终端区的情况尤为突出。为了缓解这一状况,利用标准雷达引导航线建立了基于元胞传输理论的终端区进场航班优化模型,结合实际案例,与当前实际进场运行情况进行了对比,求解得到系统运行最短时间、起点处延误时间。案例分析表明,该优化模型既能够反映终端区进场航班的动态特性,又在一定程度上减少了航班延误,可以为终端区进场航班的路径选择提供参考,满足实际的运行需求。     

成都双流机场容量与流量分配协同优化的供需平衡策略

针对成都双流机场容量资源评估需要及其流量分配中的问题,进行了机场容量与流量分配协同优化的供需平衡策略研究.采集历史的机场日常容量运行数据,利用容量包络线法来逼近机场实际容量和极限容量.在此基础上,应用整数线性规划方法建立机场容量、进港和离港容量三位一体的协同优化模型,并采用遗传算法对模型求解.查明了机场容量资源,并实现在不扩大机场容量情况下,通过对机场容量与进港和离港初始容量需求进行协同优化,最大限度满足交通需求,做到供需平衡,降低交通拥堵和航班延误的风险.     

基于多机场终端区交通态势的航班延误预测

为了针对性地制定后续优化措施,以降低多机场终端区内航班延误所带来的不利影响,并提高多机场系统内各机场的运营效率,进行多机场终端区航班延误的预测研究。首先,考虑多机场终端区交通态势对航班延误的影响,在对多机场终端区交通态势进行分析的基础上,建立了6个描述终端区交通态势的指标。接着,构建反向传播（back propagation,BP）神经网络航班延误预测模型,将终端区交通态势指标、航班信息和天气环境数据等作为输入,航班延误时间作为输出,并利用粒子群优化算法（particle swarm optimization,PSO）优化BP神经网络进行训练。通过实例验证和分析,基于多机场终端区交通态势的航班延误预测能够有效提高预测准确率,同时,通过粒子群优化BP神经网络的预测模型预测准确率均高于一般的考虑交通态势的BP和遗传算法优化的BP神经网络模型（genetic algorithm and back propagation,GA-BP）。     

基于优先级的航班到达调度算法

随着空中交通流量的迅猛增长,终端区空中交通拥堵以及由此导致的航班延误现象日益突出,甚至危及航空安全,航运效益也随之受到巨大的损失。作为终端区流量管理的核心,航班到达调度旨在为终端区待着陆的航班安排合理的着陆顺序和降落时刻,在确保安全的前提下提高进港航班运行效率。基于优先级思想,文章提出了PBSA和PBSA-CPS两种航班到达调度算法,并引入约束位置交换概念,以提高调度结果对于管制员的可操作特性。最后以首都机场为例进行了仿真,并与现行的先到先服务算法FCFS进行了对比。仿真结果表明,通过对航班赋予相应的优先级,有助于优化调配到达航班队列的降落时隙分配结果,提高终端区运行效率,减少延误损失。     

航班时刻资源优化配置与延误水平评估

针对中国大型机场由于航班时刻资源受限造成的航班延误问题,在评估机场容量的基础上,建立了降低机场航班延误水平的航班时刻分配模型。在满足机场容量限制,考虑航班连续性和中转旅客需求的约束下,应用改进的吱呀轮优化算法寻求航班调整总量最小的分配方案。以北京首都国际机场的航班时刻资源配置为例进行优化,并应用SIMMOD软件对模型设计算法,验证航班时刻优化模型的有效性。优化结果显示:北京首都国际机场的进离港延误水平都降低了26%以上,放行正常率提高了20%。     

终端区航空器排序方法研究

终端区空中交通流量瓶颈问题需要采用动态解决方案,文章应用A*启发式算法处理航班排序优化问题,在考虑航班最小安全间隔的基础上,尝试寻找最小最有进场航班序列,使航班总延误和平均延误最小。     

多元受限地面等待策略建模与分析

为了缓解航班大批量延误问题,综合考虑了恶劣天气下对航路扇区容量和目的机场容量约束,建立了以最小化延误总成本的多机场地面等待策略模型,并对航班延误成本进行了系统的研究分析,着重考虑了延误对航空公司的经济影响,指出延误成本与延误时间的指数型增长关系和连程航班的延误累积效应.利用CPLEX优化软件对多机场地面等待模型进行精确求解,根据目的机场接收率的动态变化以及不同航班单位时间延迟费用的不同,对航班的地面延误时间优化.仿真验证了其可行性,算法可求出符合各容量约束条件的满意实时解.     

基于点融合技术的机场终端区运行效率

为解决繁忙终端区运行效率低、飞行冲突严重、管制员工作负荷大、通信频道拥堵等问题,提出了一种基于点融合技术的进场航班流排序方法.通过细化基于点融合的进场航班排序过程,分析了基于点融合程序的空中交通管制工作流程;基于雷达管制模拟机设计并验证了点融合程序应用于中国西南某机场终端区的可行性.结果 表明:点融合程序能解决终端区大流量情况下的进场航班排序问题,相比于现行程序而言,雷达引导、高度速度调整指令次数均有不同程度的减少,有效降低了管制员和飞行员工作负荷,改善了陆空通话拥挤现状.同时,进场航班间的飞行间隔更均匀、有序,进场时间和间隔均有一定程度的减小,终端区空域容量和运行效率显著提升,能有效缓解航班延误.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the