基于在线图修剪的网格地图寻路

跳点搜索算法(JPS)是网格地图上最先进的图形修剪技术,由Daniel Harabor在2011年开发。它是A*的变种,提高了A*在等价网格上寻路的速度,当考虑当前节点的孩子可能被添加到OPEN集合时候,跳点搜索算法则直接从当前节点跳跃到了远处可见的节点。本文给出了跳点搜索算法的两个规则,并通过实证分析,将跳点搜索算法与两个先进的搜索空间约化算法进行了对比。结果显示:跳点搜索算法相对于Swamps(保持最优性的修剪技术)来说有显著地改进;同样,相对于很多情况下性能上占优的HPA*(次优寻路算法)也具有优越性。     

基于打破对称性的快速寻路算法

基于Java实现了跳点搜索算法,给出了算法实现的过程.实验结果表明:跳点搜索算法找到了一条从起始节点到目标节点的最优路径,且能够有效地识别和消除网格地图上的路径对称性,大幅度减少了节点扩展的数量.对比A*、宽度优先搜索、最佳优先搜索和Dijkstra可知,在所求解的路径长度一致的情况下,跳点搜索在平均搜索时间上显著快于其他算法.因此,跳点搜索是快速、高效的.     

基于跳点搜索算法的网格地图寻路

等价网格环境下的寻路问题普遍存在于机器人、电子游戏等应用领域.其中,最先进的技术都被分层寻路算法所主导,这些算法速度快且内存开销较小,但通常返回的路径都是次优的.本文提出了一个新颖的、特定于网格的搜索策略,该策略速度快、最优且无需内存开销,其算法可以描述为一个宏算符,该宏算符识别和有选择地扩展网格地图上的仅仅某些节点,我们称之为跳点,连接两个跳点的路径上的中间节点将不再被扩展.我们将证明该方法计算出的解总是优解的;然后,进行了深入的实证分析,并将我们的方法与其他文献上的相关工作做对比.我们发现利用跳点进行搜索能将A＊算法的速度提高一个数量级甚至更多;同时,我们报告了跳点搜索相对于当前最先进的技术而言有明显的改进.     

一种面向非结构化环境的改进跳点搜索路径规划算法

为解决非结构化复杂场景下基于搜索的寻路算法中存在的计算时间长、路径非最优等问题,在跳点搜索(jump point search,JPS)算法的基础上,提出一种带权重的跳点搜索(weighted jump point search,WJPS)算法.WJPS算法改进了启发式函数,同时采用非传统的距离表达,最终实现了在保证全局路径最短的同时,降低了计算时间.为了验证WJPS算法的有效性,设计了多种非结构化复杂场景地图,对A?、JPS算法和WJPS算法在寻路时间、扩展点数和路径长度3方面进行了对比.实验结果显示,相比A?算法和JPS算法,WJPS算法在复杂环境中能保证生成路径是最短的,同时利用JPS跳点算法中寻找拓展点的策略,能够实现毫秒级别的规划,且算法效率能够满足智能体对路径规划层的要求.另外,WJPS算法采用微分平坦法对生成的路径点作曲线拟合,使智能体的运动轨迹更加平滑.     

面向移动机器人快速全局路径规划的改进跳点搜索算法

针对传统全局路径规划算法计算量大,寻路时间过长等问题,为了进一步提高移动机器人综合作业能力,本文提出了一种基于跳点搜索算法的快速全局路径规划算法,旨在减少时间成本,以满足移动机器人在实际复杂环境中对智能性、高效性、安全性和可靠性的要求。首先通过“块”操作方法,在一次搜索中快速扫描底层网格中的一个区域,将跳点搜索算法的修剪规则一次应用于多个节点,减少搜寻跳点时所涉及的大部分迭代计算,并在采取“对角优先”方式的前提下,剔除仅具有改变方向的中间转折点,大量减少Openlist和Closedlist的不必要节点,减少计算量,提高路径规划的实时性。为了验证改进算法的有效性与可行性,分别在规则的网格地图、测试库基准地图及移动机器人Turtlebot2进行仿真实验验证,结果表明在生成相同路径的基础上,改进跳点搜索算法与A*算法相比扩展节点数目缩减了68.9%,搜索耗费时间降低了71.9%;与传统跳点搜索算法相比,扩展节点数目缩减了41.3%,搜索耗费时间降低了33.4%,能够满足移动机器人快速全局路径规划的要求。     

基于密度分类的JPS+移动机器人全局路径规划算法

近年来,跳点搜索(Jump Point Search, JPS)算法在移动机器人的全局路径规划中得到广泛运用,但其本身存在计算量较大、用时较长等问题。因而有人又提出了通过地图预处理提高效率的JPS+算法,但仍然在计算量和用时上有改进空间。针对业界存在的现实问题,首先介绍了JPS+的主要工作,并对JPS+算法进行了详尽分析,继而阐明了本文提出的两点改进策略。一是引入了一种基于密度的判断障碍物角点规则,进而减少主要跳点的数量;二是在进行最短路径求解过程中对目标跳点的判定规则进行了修改,从而实现了减少计算量、缩短计算时长的目标。为验证所提改进型JPS+算法的有效性,将JPS+算法在不同类型地图中与改进型JPS+算法进行了比较。仿真结果表明,改进型JPS+算法在多种地图中均能有效提高搜索速度,路径规划也十分合理,由此证明所提改进型JPS+算法对于全局路径规划具有实用价值和推广意义。     

基于改进A*算法的燃气微泄漏四足巡检机器人路径规划

针对四足机器人在城市燃气微泄漏巡检中路径规划的需求,提出了一种基于改进A*算法的四足机器人燃气巡检路径获取方法。首先,采用网格法构建了四足机器人的二维工作地图。然后改进A*算法的启发函数,引入了自适应调整策略,让搜索节点减少且路径更不易陷入局部最优。最后从路径长度、平均搜索时间、搜索节点个数三个性能方面进行评估,改进A*算法达到了预期效果。使用Matlab2016b作为仿真软件,仿真结果显示,改进A*算法完成了寻路任务。与经典A*算法相比,改进算法的平均搜索时间降低了52.13%,搜索节点个数减少了30.23%。该算法在尺寸200×200以下地图的路径规划中具有较高的搜索效率。     

融合插点和跳跃点改进A*算法的路径规划

为了解决传统A*算法在路径规划中存在的一些问题,提出了一种融合插值点跳跃搜索路径算法来改进A*算法。在对栅格环境图中具有特殊意义的多组数据进行预处理后,通过起始点和目标点确定目标函数,并搜索出一条最优路径。利用MATLAB软件平台对8组规格不同的环境图进行了路径规划仿真。实验结果表明,改进后的算法可以减少计算时间、搜索节点数量、内存占用和搜索路径长度。可见改进后的算法在搜寻最佳路径方面的效率更高。     

基于同步可视图构造和A~*算法的全局路径规划

为提高全局路径规划的效率,在路径搜索的过程中同步构造可视图,提出了1种新的算法。在搜索过程中,使用A~*算法确定待扩展的节点。根据节点状态,构造上一节点到当前节点或者当前节点到目标点的连线。如果该连线没有穿越障碍物,则将其添加到可视图中,否则将被穿越障碍物远离连线的2个顶点添加到待扩展列表中。仿真结果表明,与完整可视图+A~*算法、导向可视图(OVG)+A~*算法、简化可视图+A~*算法比较,该文算法在能够搜索到最优路径的前提下,降低了路径规划的耗时。     

基于双向同时无碰撞检测目标偏置RRT算法的路径规划方法

针对传统RRT算法在复杂环境中对不必要区域的搜索和路径规划的时间代价过高等问题,提出了一种双向同时无碰撞检测目标偏置快速扩展随机树算法——TNCG RRT*。该算法将B RRT*中的双向搜索策略和BIT*中的启发式搜索融合作为文中的基础算法,引入神经网络的批量抓取数量决定一次采样的节点数目从而影响采样速度;然后,将正向树和反向树的扩展同时进行以加快路径搜索速度,通过对目标偏向策略中扩展顶点队列的改进和对采样区域的不断更新明确扩展方向,缩小随机树生长的范围;最后,利用3次B样条曲线使生成的路径趋于平滑。与B RRT算法和BIT*算法进行对比实验,实验结果表明:TNCG RRT*算法在路径生成时间上缩短4.5%,剪枝数增加80%,路径代价（即路径长度）缩短9%,证明了TNCG RRT*算法的有效性。     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

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

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.