多工况应力约束下的连续体结构拓扑优化映射变换解法

针对多工况连续体结构拓扑优化常见模型中存在的目标函数非连续性,基于独立连续拓扑变量概念及映射变换方法,建立了多工况应力约束下连续体结构拓扑优化新的连续模型,考虑多工况结构拓扑优化中“荷载病态”现象,提出应用荷载加权系数的单元删除准则及分层优化算法求解,算例验证了本文方法的正确性和高效性。     

基于整车虚拟样机的车体结构拓扑优化

基于整车零部件几何模型,结合车体的有限元网格划分及模态分析,构建履带装甲车辆刚柔混合虚拟样机,进行典型工况下的多体动力学仿真分析,输出若干关键时间点车体承受的荷载.利用有限元分析技术将荷载加载到车体有限元模型上,对车体进行结构力学分析和多荷载步拓扑优化.根据拓扑优化结果修改车体局部结构,并重新构建虚拟样机模型再次进行仿真分析,将应力和变形分析结果与原仿真结果进行比较.结果表明,结合动力学仿真和有限元分析进行结构拓扑优化,可以改善关键零部件的力学性能,提高刚强度,为改善装甲车辆的结构性能提供了一种有效方法.     

荷载工况多目标下钢筋混凝土深梁的拓扑拉压杆模型设计

为了提高钢筋混凝土深梁构件配筋设计方法的合理性,选用遗传演化结构优化算法,并延伸出荷载工况多目标下的应用方式,同时基于拓扑解构建拉压杆模型,衔接拓扑优化与工程设计环节,建立荷载工况多目标拓扑拉压杆模型。采用两个深梁数值算例验证了该模型的可行性和稳定性。从建立拉压杆模型的角度以其力学特性出发,将荷载工况多目标优化的拓扑解分别与各荷载工况单目标优化解、其弹性叠加结果,以及所有荷载工况共同作用下的单目标优化解进行比较,证实了新模型更契合深梁类构件的受力特性,具有更佳的全局寻优能力。荷载工况多目标遗传演化结构优化可以有效解决多目标优化中的病态荷载问题,依据其建立的拉压杆模型直观可行,可以为钢筋混凝土深梁设计提供参考。     

连续体结构拓扑优化设计的ICM方法

基于独立连续拓扑变量及映射变换（ＩＣＭ）的拓扑优化方法应用于连续体结构,建立了统一的以重量为目标、考虑应力约束的连续体结构拓扑优化模型．提出基于综合评价的高效单元删除准则及算法．给出的经典的二维和三维连续体结构拓扑优化算例表明,这种统一的模型由骨架结构发展到连续体结构的拓扑优化也是成功的．该方法具有算法简单、收敛速度快和稳定性好等优点     

基于类桁架材料模型优化方法计算稳定性研究

推导了2相正交类桁架材料模型,建立了基于类桁架连续体材料模型的单工况和多工况应力约束拓扑优化方法.以杆件在结点位置的密度和方向为设计变量,在单工况下,采用满应力准则法优化杆件密度,将杆件方向与主应力方向对齐;在多工况下,采用方向刚度包络线拟合的方法,由各单工况优化结构导出.通过反复迭代形成类桁架连续体材料优化分布场,进而形成类桁架结构.通过3个经典算例,验证了不同有限单元网格密度和形状下该拓扑优化方法的稳定性,克服了各种拓扑优化普遍存在的单元依赖性.     

结构拓扑优化方法在拱式渡槽拱轴线设计中的应用

针对拱式渡槽拱轴线的受力特点,建立拱轴线拓扑优化模型,并将结构拓扑优化方法生成的拱式渡槽拱轴线与相同矢跨值的圆弧拱轴线和二次抛物线拱轴线进行了对比.结果表明,由结构拓扑优化方法生成的拱轴线,自重作用下的弯矩值以及相同均布荷载作用下的应力值都比相同矢跨值的圆弧拱轴线和二次抛物线拱轴线小.这说明连续体结构拓扑优化方法可应用于作用荷载相对均匀的拱式渡槽拱轴线设计.     

塔式起重机臂架周期性拓扑优化设计

为实现塔式起重机臂架桁架结构腹杆的布局优化,提出了基于连续体拓扑优化的桁架结构优化设计方法.首先去除起重臂腹杆,用腹板代替,同时为克服臂架细长难以进行拓扑优化的特点,将起重臂划分为若干个优化周期,建立臂架的周期性板梁优化模型;然后使用周期性SKO(soft kill option)方法对腹板进行连续体拓扑优化,优化中使用温度过滤函数消除棋盘格式现象,得到优化的腹板拓扑构型;最后使用有限单元8-邻域网格模型骨架提取算法得到腹板拓扑的中心骨架进而得到优化的腹杆布局.选取QTZ63塔式起重机最大幅度、最大起重量和最大应力3种典型工况作为优化工况,并考虑起升动载荷、风载荷及惯性载荷进行优化设计.基于3种典型工况,从强度、刚度、稳定性方面对原臂架和优化臂架进行了对比分析,验证了优化方法的有效性.     

几何非线性连续体结构拓扑优化仿生方法

利用基于Wolff法则的仿生方法对几何非线性、线弹性连续体进行拓扑优化.该仿生方法中引入构造张量作为设计变量用于描述设计域内各点处材料微结构的几何特征及其宏观弹性本构.同时,引入参考应变区间并结合Wolff法则用于确定结构中某点处材料的更新方案.考查了结构最优拓扑的网格依赖性以及参考应变区间对结构的最优拓扑及材料分布的影响.数值算例表明,结构的最优拓扑无网格依赖性.几何非线性线弹性连续体结构的最优拓扑明显地依赖于参考应变区间的选取.如果参考应变区间长度为零且荷载为指定位移时,按同比例改变荷载及参考应变区间上确界,可得到相近的最优拓扑和材料的分布.     

不同荷载工况下钢筋混凝土深梁的拓扑优化设计

为探讨不同荷载工况对钢筋混凝土深梁拓扑优化的影响,同时改进当前深梁设计方法,采用渐进演化类拓扑优化算法寻求钢筋混凝土开洞深梁在不同集中加载工况和荷载集度工况下的最优拓扑结构,再依据这些最优拓扑结构建立相应的压杆[CD*2]拉杆模型,并分析这些最优拓扑结构和压杆[CD*2]拉杆模型的差异。结果表明：压杆[CD*2]拉杆模型均为较符合满应力分布的Michell结构;集中荷载作用在梁顶时,荷载从加载点通过最短直线压杆以压力的形式向支座传递;集中荷载作用梁腹和梁底时,荷载则通过伞状拉杆悬吊在主压拱上,再向支座传递;随着荷载集度降低,最优拓扑结构向拱或拱[CD*2]组合压杆的组合体系演化。在工程设计中,对于不同荷载工况条件下的钢筋混凝土深梁,可以参照最优拓扑结构在内部有针对性地设计隐藏的受压加强构件或受拉钢筋。     

汽车转向节静动态特性分析与多目标拓扑优化

为使复杂工况下运行的SUV汽车在满足各项性能要求的基础上实现轻量化,以汽车转向节为研究对象,利用变密度连续体结构拓扑优化与折衷规划法相结合来建立多目标优化函数模型,利用层次分析法确定各子目标的权重,进行多目标拓扑优化,得到了材料的理想分布.优化前后的转向节静动态特性对比分析表明,采用多目标拓扑优化方法设计的汽车转向节在轻量化的基础上提高了其结构的刚度和固有频率,实现了多目标同时优化.     

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.