集中载荷高速履带车辆稳态转向模型分析

基于履带车辆接地压力分布复杂,模型计算精度不够准确等问题,考虑履带车辆的滑移和滑转,以及离心力作用,分析集中载荷接地压力分布特点并建立剪切模型。分析不同转向速度和不同相对转向半径下履带车辆稳态转向过程各性能参数变化趋势。最后将转向试验数据与计算结果进行对比验证。     

履带车辆软地面稳态转向驱动力计算模型

通过对履带车辆稳态转向时接地履带剪切位移计算式的引入,根据接地履带与地面间的剪切应力与剪切位移及驱动力与剪切应力计算关系,考虑接地履带滑转(滑移)及转向中心偏移等因素,建立了履带车辆软地面稳态转向驱动力计算模型。参考某型号橡胶履带拖拉机已知参数进行了试验及仿真分析,仿真结果与试验结果有较好的一致性。     

基于新型双功率流差速转向机构的履带车辆转向性能

转向机构直接影响履带车辆的转向性能。传统机械式双功率流差速转向机构只能实现数目有限的转向半径,并且往往需要制动器等元件,为此,设计一种具有连续转向半径且可避免磨损的新型机械式双功率流差速转向机构;建立差速转向机构的两电机轴(输入)转速与两半轴(输出)转速的运动学模型。根据两半轴转速与履带车转向半径之间的关系,得到履带车的两电机轴(输入)转速与转向半径的运动学模型;建立考虑履带宽度以及滑转、滑移的履带车稳态转向数学模型;最后进行运动仿真和理论分析对比研究。研究结果表明:对差速转向机构的转速仿真结果与理论值相对误差最大为1.50%,且能够使履带车辆实现任意的连续转向半径,该研究成果能为履带车辆的电机选取、转向控制以及结构优化等提供理论参考。     

特种履带车辆小半径转向功率匹配机理研究

针对特种履带车辆小半径转向功率匹配难以计算的问题,建立了特种履带车辆小半径转向功率匹配计算模型,推导出在考虑履带接地比和履带宽度的情况下,该特征车辆小半径转向功率匹配的修正模型,并利用某型军用特种履带车辆的相关参数对该模型进行了仿真,结果表明:小半径转向功率匹配随转向半径变化而变化,转向内侧履带较外侧履带变化更明显;转向摩擦阻力矩对功率匹配特性影响更大;该仿真结果与某型军用特种履带车辆电机功率选型相一致。这为特种履带车辆驱动部件选型及整机结构设计提供了一定的理论依据。     

基于RecurDyn的平架湿地型履带推土机转向性能分析

为使平架湿地型履带推土机在湿地路面实现更高效转向，分析湿地土壤物理特性对该类车辆转向性能的影响.利用PRO/E和RecurDyn软件创建履带推土机三维模型，建立不同含水量湿地路面模型，对模型进行不同载荷下的多体动力学仿真，对比分析履带推土机转向半径、转向极横向偏移量、左侧履带驱动牵引力和右侧履带制动力，得出不同湿地土壤、不同载荷下平架湿地型履带推土机的转向性能参数变化规律.     

履带车辆液压机械差速转向操纵系统性能分析

液压机械差速转向机构是结合了液压传动无级调速和机械传动高效率等优点的一种新型履带车辆转向机构。本文根据履带车辆的转向特点,对液压机械差速转向操纵系统组成及工作原理进行分析,建立转向操纵系统运动模型和仿真模型,仿真分析其动态特性。仿真结果表明,所设计的转向操纵系统具有良好的稳定性和动态特性,能满足履带车辆液压机械差速转向行驶要求。     

履带滑移和转向中心线偏移对车辆稳态转向特性的影响

履带车辆的稳态转向特性直接影响到其工作效率以及安全性。本文建立了履带车辆稳态转向的数学模型并提出了数值求解方法,将履带滑移半径以及转向中心线移动量作为其稳态转向特性的评价指标,并进行了仿真分析,结果表明:随着转向半径和车速的变化,滑移半径以及转向中心线移动量的增大或减小,影响车辆的转向稳定性。     

履带车辆转向机构的研究现状及发展趋势

履带车辆的转向机构是重要的总成之一，其性能的优劣直接影响着车辆的转向机动性和生产效率。因此对性能优良的转向机构的研究一直是车辆工程领域的重要研究课题。本文从履带车辆传统转向机构的构成出发，介绍了各种转向机构的优缺点及新型转向机构的工作原理和研究现状，指出履带车辆转向机构的发展趋势是大力加强对机动性高、能耗低、性能优良的机械液压连续无级转向机构的研究与开发。     

履带车辆软地转向性能理论分析

建立了一个履带车辆软地稳态转向模型,模型中考虑到了车辆沉陷、纵向倾角等因素;对模型参数进行了数值计算,并以此分析了土壤、车辆结构诸多参数对转向性能的影响.     

地面不平条件下考虑滑动转向特性的履带车辆路径跟踪控制

针对履带式车辆自主行驶控制中滑动参数难以精确估计和在复杂地面条件下难以稳定跟踪目标路径的问题,提出一种考虑履带车辆滑动转向特性的改进模型,并以此为被控对象设计基于深度强化学习方法的路径跟踪控制器.首先,基于球?面接触原理建立履带车辆的动力学模型.其次,提出基于实车稳态转向实验数据的滑移率估计方法,并结合履带车辆的滑动转...     

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.     

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.     

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.     

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.     

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.