某专用校车顶部安全性能仿真与改进

为提高专用校车顶部安全性,对某专用校车在翻滚事故中的顶部结构对乘员的保护作用进行了研究.利用Hypermesh与Hypercrash软件建立其车身有限元模型.针对碰撞包含几何非线性、材料非线性和边界非线性的特点,选择并定义了合适的非线性材料和壳单元,进行了焊接及其他连接方式的模拟.利用RADIOSS求解器,进行校车翻滚保护仿真及乘用车顶部抗压强度仿真.结果表明:在翻滚保护仿真中,该车车身结构能承受标准要求的1.5倍整备质量载荷,在顶部抗压强度仿真中,施力板下表面侵入量为46 mm,满足标准要求.参照有关国际标准,对A柱及横梁结构进行改进设计,使单根横梁的最大承载能力达到64700 N,提高了该车的翻滚保护性能.     

多学科与多材料匹配的客车车身轻量化优化设计

提出基于多材料匹配与模块化设计的客车车身轻量化设计方法.基于车身轻量化设计的多学科特性,结合Kriging近似技术与协同优化设计方法,建立基于侧翻安全性、顶部抗压学科的客车车身多学科优化设计模型,并采用遗传算法进行多学科数值寻优.优化结果表明:基于灵敏度分析的模块化设计能较好地降低车身设计维度,并获得具有较好力学性能的多材料匹配客车车身;多材料车身不仅改善车身的安全特性,而且提高车身顶部的抗压强度,并较好地达到轻量化设计的要求.     

侧翻安全性的校车侧围结构轻量化设计

根据《客车上部结构强度的规定》对校车车身结构侧翻安全性的规定,建立和验证某校车有限元分析模型.采用均匀设计方法对校车的侧围结构厚度参数进行多水平多因素实验设计和侧翻仿真分析,并拟合实验设计数据获得轻量化水平较优的因素水平组合.结果表明:在侧围结构满足法规对生存空间要求的前提下,选择因素水平组合U₂₄₆₅并参考实际型钢的厚度规格(1(1.0,1.0),2(2.0,1.5),3(3.0,2.0),4(2.5,2.0)),可使侧身结构质量轻量化24.39%.     

基于LS-DYNA的校车侧翻有限元分析

基于LS-DNYA软件,对某型号校车建立有限元模型,参考GB 17578-2013进行校车动态翻滚碰撞过程的仿真研究,并依据仿真结果对原结构进行优化加强,使其满足国标要求。     

大功率船用齿轮箱结构优化

综合考虑齿轮啮合力及箱体重力作用,采用有限元法建立大功率船用齿轮箱的有限元静力学模型,分析计算4种工况下齿轮箱的承载能力,并对原齿轮箱的强度和结构刚度进行分析评价.基于等强度原则,将优化设计与可靠性设计理论相结合,建立齿轮箱优化模型.在满足齿轮箱结构安全的条件下,对齿轮箱进行优化设计.优化后的齿轮箱重量减轻1.06 t,并且强度分布趋向均匀,结构变得更加合理,具有一定的理论和工程实用价值.     

基于双地震动强度指标的桥墩地震易损性模型研究

基于双地震动强度指标,开展典型桥墩的地震易损性模型研究.采用Open Sees软件建立桥墩的有限元分析模型,通过增量动力分析方法计算得到桥墩的地震响应.根据受试者工作特性分析方法对地震动强度指标进行评价,选择出有效性较好的地震动强度指标组合,基于线性组合的方法分别建立双地震动强度指标桥墩易损性模型,并和单地震动强度指标模型进行对比.结果表明:双地震动强度指标的有效性普遍优于单一地震动强度指标;桥墩发生相同损伤状态时,基于双地震动强度指标建立的易损性曲面的中位值小于基于单一地震动强度指标得到的中位值.研究结果可为桥梁结构的后续风险评估及加固决策提供参考.     

基于均匀色差空间向量分解模型的彩色图像质量评价方法

针对三要素(亮度、色调和饱和度)空间方法缺乏视觉均匀色差思想的支持,而均匀色差空间方法又需要其他有效评价模型的补充,该文立足于图像的两个基本属性,即光特性(亮度、色调和饱和度)和结构特点,结合反映彩色空间特性的均匀色差空间模型以及空间向量分解模型,提出了均匀色差空间向量分解模型.实验结果表明基于均匀色差空间向量分解模型较传统评价方法和单项模型更能够全面地评价彩色图像质量.     

X形柔性铰链等效刚度分析及结构特性研究

基于抗压双片段柔性铰链,设计了4片段X形柔性铰链,并对其结构特性进行了研究.X形柔性铰链中的主要变形片段为弯扭耦合片段,分别运用微分法和基于抗压双片段柔性铰链等效刚度算法分析了其弯扭耦合等效刚度,推导出了X形柔性铰链的等效刚度理论计算公式.设计了几组不同尺寸的X形柔性铰链实例,分别利用2种方法对这些实例进行了计算,并在ABAQUS软件中进行了仿真分析,3种分析方法结果表明了理论计算公式和仿真模型的正确性.最后,通过对不同尺寸的X形柔性铰链结构特性的分析,得到了铰链设计时应该尽量避免的结构参数范围.     

规则递归T-S模糊模型及其辨识方法

针对传统T-S模糊模型不能较好描述系统时变特性的问题,提出了一种基于递归策略的动态T-S模糊模型及其辨识方法.规则递归T-S模糊模型在传统T-S模糊模型基础上,增加了具有一定权重的反馈环节,该环节对当前激励强度与前一时刻激励强度进行加权和得到当前时刻新的规则激励强度,从而实现动态递归变化,有效描述了系统的动态过程.为使规则递归T-S模糊模型具有较少的规则数量和较好的泛化能力,前件参数采用一种基于规则激励强度的模糊聚类算法获得,而后件和递归环节参数则采用一种由支持向量机和粒子群优化算法组成的联合辨识方法获得.Box-Jenkins煤气炉的仿真结果表明,规则递归T-S模糊模型及其辨识方法具有较好的动态描述能力,与混合聚类方法相比,均方差降低了1.2％.     

基于递推动力学的汽车悬架实时仿真模型

针对车辆动力学实时仿真的要求,面向悬架具体结构,应用递推动力学方法,建立了悬架系统模型.模型由于铰链相对坐标的引入,减少了需求解的方程数目,提高了求解效率,使模型既能面向悬架具体结构,又能够满足车辆动力学实时仿真的需要.基于这种建模方法建立了国产某轿车的麦弗逊式悬架模型,并进行仿真,其结果与道路试验及ADAMS仿真结果有较好的一致性,验证了模型的精度.     

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。     

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.