基于神经网络的渐开线圆柱齿轮动态优化设计

通过分析渐开线圆柱齿轮振动力学性能 ,建立了渐开线圆柱齿轮动态优化设计模型。利用BP神经网络映射齿轮动态响应与设计变量之间的函数关系 ,提高优化设计效率。对直齿轮传动动态优化设计的结果表明该方法是行之有效的。     

三级圆柱齿轮传动的系列优化设计算法探析

三级圆柱齿轮系列优化设计的数学模型包含有连续变量和离散变量,分析各设计变量之间的关系和约束条件,并考虑各设计变量对系列优化目标的影响,将三级传动系列优化设计问题转换为传动比分配优化设计与每一级齿轮传动优化设计问题的求解。     

基于混合离散变量复合形法的弧齿锥齿轮优化设计

以齿数Z1,模数m,齿厚系数ψR作为设计变量,建立弧齿锥齿轮的物理模型,以体积最小、传递功率最大为目标,以齿轮的强度要求等作为约束条件的优化设计模型。由于齿数和模数是非均匀的离散设计变量,齿厚系数是连续变量,因此,借鉴了连续变量和非均匀离散变量的处理方法———一种混合离散复合形法,并引用离散变量搜索优化方法。在混合离散复合形法基础上,探讨了解决有约束非线性混合离散变量的优化设计问题。经实例计算结果表明,混合离散复合形法可用于具有实际应用价值的弧齿锥齿轮优化问题。     

时变啮合刚度作用下直齿与斜齿圆柱齿轮的振动特性分析

作为传递动力与能量的关键部件,齿轮系统在石油石化装备中有着十分广泛的应用。针对常用的直齿与斜齿齿轮传动系统,分别利用能量法与累计积分能量法建立了直齿与斜齿圆柱齿轮齿的变截面悬臂梁模型,对比分析了直齿与斜齿圆柱齿轮系统时变啮合刚度的基本特性。利用集中参数法,分别建立直齿与斜齿圆柱齿轮齿的弯扭耦合振动模型。利用Nemark-β数值积分法对模型进行了仿真求解,对比分析了时变啮合刚度作用下直齿与斜齿圆柱齿轮系统的振动特性。结果表明:直齿圆柱齿轮时变啮合刚度存在阶跃性突变,而斜齿圆柱齿轮时变啮合刚度波动较为平稳。由于直齿圆柱齿轮时变啮合刚度的阶跃性突变,直齿圆柱齿轮的振动幅值与冲击响应要远远大于斜齿圆柱齿轮。本文阐明了直齿与斜齿圆柱齿轮在时变啮合刚度及振动响应上的异同点,从动力学分析的角度揭示了斜齿圆柱齿轮系统传动平稳的内在机理,可为齿轮传动系统的减震降噪及结构优化提供理论基础。     

高副接触摩擦学设计模型的构建

给出了直齿圆柱齿轮传动的强度设计模型 ,建立了润滑设计准则 ,并进而建立了直齿圆柱齿轮传动的摩擦学设计模型     

基于复合—遗传算法斜齿轮减速器优化设计

针对标准复合形算法在设计变量较多时容易陷入局部最优的缺点,提出了复合形—遗传算法.建立了两级斜齿圆柱齿轮减速器的结构参数优化模型,并开发了相应的计算程序.以齿轮中心距之和为优化目标,在所确定的约束条件下,采用复合形—遗传算法对两级斜齿圆柱齿轮减速器进行结构参数优化设计.结果表明,减速器原方案并不是最优方案,尚有较大的优化空间,同时优化结果也证明该优化设计方法的可行性.     

采用NSGA-Ⅱ算法的面齿轮副小轮拓扑修形多目标优化

为合理确定面齿轮副小轮的修形参数,设计了均由2段抛物线与1段直线组成的直齿小轮齿廓和齿向修形曲线,将由三次B样条拟合得到的修形曲面与理论齿面相叠加来构造拓扑修形齿面。采用带精英策略的快速非支配排序遗传算法(NSGA-Ⅱ),结合面齿轮副的几何接触分析(TCA)和承载接触分析(LTCA)技术,提出了以修形曲线参数为优化变量,使抛物线几何传动误差曲线两端对称、接触印痕限制在齿宽中部、承载传动误差波动幅值最小的小轮拓扑修形多目标优化设计方法,并编制了相应的Matlab程序。算例表明:优化修形参数后得到了对称的抛物线几何传动误差和位于大轮齿宽中部的接触印痕,并大幅度减小了承载传动误差波动,从而可有效降低安装误差敏感性和齿轮副的振动、噪声。     

齿轮噪声产生机理及控制方法

齿轮传动是目前应用最为普遍的传动方式,渐开线直齿圆柱齿轮齿型加工比较容易,相对加工误差比较小,加工手段和加工方法多样,决定了其应用的广泛性。本文对渐开线直齿圆柱齿轮传动噪音与振动的产生原因以及如何采取相应的控制措施等方面作了分析,对其他不同啮合方式的齿轮传动也提供了借鉴。     

基于UG NX和ANSYS的减速箱渐开线圆柱齿轮有限元分析

通过三维机械设计软件UG NX构建直齿圆柱齿轮几何实体模型,运用有限元分析软件ANSYS对齿根进行应力分析计算,计算出齿轮的最大应力和最大应变.通过与理论分析结果的出较,说明ANSYS在齿轮计算中的有放性.有限元分析有利于对齿轮传动过程中力学特性进行深入研究,为齿轮传动的优化设计提供了基础理论.     

汽车动力传动系参数的优化方法

在讨论分析普通的汽车传动系参数的普通优化方法和汽车传动系参数的模糊优化方法的基础上 ,提出了汽车传动系参数的区间优化方法 在这一模型里 ,设计变量变为区间数 ,优化目的是在保证一定的汽车基本性能的前提下 ,求设计变量的最大可行区间 它可以解决变速器优化设计中齿轮配齿问题 实例对比表明 ,采用区间优化方法更加符合工程实际     

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.