步行式挖掘机方向纠偏控制参数多目标优化方法

针对步行式挖掘机自行上运输车过程中，实现一次方向纠偏控制参数的求解问题，建立了步行式挖掘机方向纠偏时的运动学微分方程，构造了一种求解方向纠偏控制参数多目标优化模型，用两级优化模型对纠偏控制参数进行求解。第一级优化模型利用信赖域法对一阶微分方程进行求解，得到步行式挖掘机方向纠偏过程中的运动参数；第二级优化模型用序列二次规划法对多目标优化模型求解，得到不同接近角情况下一次纠偏控制优化参数。利用仿真分析对第一级优化模型进行了验证。研究表明，建立的步行式挖掘机纠偏模型正确，当接近角小于25°时，步行式挖掘机可实现一次方向纠偏，所提出的两级优化模型控制参数求解方法可为步行式挖掘机无人化纠偏提供理论依据。     

轮履变体式车辆底盘越障性能研究

对全地形轮履变体式车辆底盘的典型越障性能进行研究.首先,参考某型车辆底盘,设计轮履复合轮（即变体轮）尺寸,建立三维模型;通过运动学和力学分析,确定出变体轮跨越壕沟、攀爬台阶及爬坡的临界状态,得到最大越壕宽度、最大越台阶高度和极限爬坡度.结果表明,轮履变体式车辆底盘具有很强的环境适应能力和较高的越障性能,且整体越障性能优于传统轮式和履带式车辆.这些为轮履变体式底盘的结构优化以及未来轮履复合式车辆的广泛应用提供了充分的理论依据.     

核探测机器人底盘设计与越障性能仿真验证

为减少核辐射对工作人员身体的损伤,设计了一款可用于强辐射环境的、具有较好通过性和地形适应能力的附有减震系统的核环境探测机器人。该机器人搭载多种探测传感器并对关键驱控部分进行了辐射屏蔽,可在强辐射环境下完成探查、巡检作业;机器人的履带移动底盘设计采用驱动轮与地面具有一定角度的离地角同时使诱导轮接地的方法以保证机器人具有较好的越障性能和地形适应能力;底盘设计了减震结构以减少机器人震动对探测器造成的影响。通过理论分析确定了移动底盘相关参数,通过三维绘图软件SolidWorks建立了机器人三维模型,利用动力学仿真软件RecurDyn对机器人底盘越障能力进行了仿真分析,得出了机器人在越障过程中其质心与驱动扭矩的变化关系,验证了底盘越障可靠性,为实验样机的研制奠定了理论基础。     

基于ADAMS的载人月球车性能分析

以载人月球车为研究对象,对月球车转弯性能和抗倾覆性能进行了理论分析.利用PATRAN和ADAMS建立了月球车车轮、底盘、悬架及月面环境模型,对月球车转弯性能进行了分析,并对月球车爬坡、两侧同时越障、单侧越障、越过沟壑时的俯仰稳定角、滚转稳定角进行了仿真.结论指出:转弯半径随着内外侧车轮转速比的减小而减小,当转速比为0时该月球车模型具有最小转弯半径2.4 m;坡度对俯仰稳定角的不利影响最大,月球车爬坡时俯仰稳定角的减小值与坡度的倾斜角度相等,滚转稳定角受沟壑的影响最大.     

挖掘机在复杂路面条件下行走稳定性仿真

研究履带式挖掘机行驶过程中的跑偏及履带系统的受力情况.应用PROE建立挖掘机的主体模型,将其导入到多体动力学软件RecurDyn中,利用RecurDyn建立挖掘机行走履带系统的虚拟样机模型,应Ground模块建立路面横、纵向倾斜模型,仿真研究了挖掘机在复杂路面条件下行驶时履带部张紧油缸的受力、驱动轮的受力与矩特性,以及挖掘机重心的位移、加速度变化情况.仿真结果表明:挖掘机在上、下坡过程中履带各关键部件受力存在一定的冲击,行走时存在着的跑偏现象,路面纵向坡度对跑偏影响较大,横向坡度次之.通过对仿真结果的分析得出加大张紧油缸的预张力能够减小上、下坡过程中跑偏及振动状况.     

全地形仿形行走车辆研究与试制

针对现有的车辆在崎岖的丘陵山区作业时出现的地面适应性差、车轮易打滑、附着力不足等问题,根据丘陵山区特殊的工作环境,采用底盘多自由度大变形的方法,设计一种适应丘陵山区农业作业的8轮驱动全地形仿形车辆,并计算分析相关设计参数.该车辆由底盘、车身和控制系统等组成,采用遥控控制方式.试验结果表明:爬坡度i为0.68,纵向通过半径R0为0.62 m,崎岖路面行驶时在极限范围内车轮不会出现悬空现象,适合丘陵山区农业使用.     

电动车全铝框架式车身拓扑分析及参数化优化方法

针对电动车全铝框架式车身优化时应当兼顾多种类型的型材和板材变量的问题,提出一种基于拓扑优化及隐式参数化模型的集成多目标优化方法。为了获得材料分布及载荷传递合理的框架式车身结构作为后续多目标优化的参考,概念设计阶段对原车身进行拓扑优化设计。基于拓扑优化结果建立车身隐式参数化模型,并利用参数化模型建立响应面近似模型以实现全铝框架式车身多目标优化的自动流程化。结果表明,全铝框架式车身在各项性能保持在目标范围的前提下减重11.9%。因此,基于拓扑优化及隐式参数化模型的集成多目标优化方法能够有效提高全铝框架式车身轻量化优化的效率和准确性。     

分布式全线控电动汽车的底盘集成控制

针对分布式全线控电动汽车四轮独立驱动/独立制动/独立转向的结构特点,提出一种基于分层架构的底盘集成控制策略.该策略包括参考目标设定、集成控制层以及控制分配层3个主要部分.参考目标设定主要实现驾驶员操作信息与车辆控制目标的转换,从车辆水平方向上可以划分成纵向加减速特性和侧向操纵稳定性;集成控制层利用具有反馈校正特征的模型预测控制方法实现对整车控制力和力矩的多目标优化;控制分配层以各车轮轮胎负荷率最低为优化目标,实现对各车轮驱动力矩和车轮转角的分配.从仿真分析和实车低速工况验证的结果来看,所提出的底盘集成控制策略能够使车辆在实际行驶时较好地跟踪参考目标,并通过控制各轮胎负荷率近似相等来提高车辆的稳定性.     

有轨电车长枕埋入式轨道复合地基多目标优化

为研究有轨电车长枕埋入式无砟轨道复合地基结构的关键影响因数和最优参数组合,采用有限单元法建立了长枕埋入式无砟轨道复合地基三维精细化计算模型.通过响应面试验得到了无砟轨道复合地基结构力学性能的响应面函数,并采用遗传算法进行多目标优化得到最优参数组合.结果表明:采用响应面模型替代有限元模型进行优化分析,可以大大减少优化迭代所需要的计算时间,且能够保证足够的计算精度;建议在进行长枕埋入式无砟轨道复合地基设计时将钢轨垂向位移作为关键评价指标;各设计变量对长枕埋入式无砟轨道复合地基结构力学性能影响的主次顺序依次为轨道板厚度、桩径、支承层厚度、桩纵向间距;最佳设计方案为轨道板厚度0.32m,支承层厚度0.18 m,桩径0.55 m,桩纵向间距1.6 m.     

摇臂式月球车的运动学建模及悬架参数优化

为了减小摇臂式月球车在崎岖不平的月球表面上行进时车体位姿的变化,给车栽科学仪器提供稳定的移动工作平台,对悬架结构参数进行了优化.在对摇臂悬架简化的基础上,定义了悬架的运动学参数,用坐标变换法建立了摇臂月球车的运动学模型,得到了以悬架运动学参数表示的车体位姿方程.以车体位姿中的垂直位移和俯仰角的变化为多目标函数,悬架结构参数为设计变量,建立了多目标优化数学模型,并利用MATLAB优化工具箱进行了优化求解.采用ADAMS软件进行了仿真分析,结果表明,优化后摇臂式月球车车体位姿的变化明显减小.     

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.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.