“平面连杆机构设计及分析平台”在《机械原理》课程中的应用

本文针对平面连杆机构设计比较复杂和抽象,研究开发了一种平面连杆机构设计及分析平台,建立连杆机构的选择模块、参数化设计模块和运动仿真模块,该平台操作性强,简单易行,可以满足不同的教学实验需要。     

AUTOCAD绘图软件包的指令文件在刚体导向中的应用

本文提出在用圆心曲线和圆点曲线进行刚体导引时,采用AUTOCAD绘图软件包的指令文件,可自动生成圆心曲线和圆点曲线图形;并提出用圆心曲线和圆点曲线的图形设计四连杆机构的一种可动性检验方法——用AUTOCAD绘图软件包的指令文件,对所设计的四连杆机构在计算机屏幕上进行运动模拟。     

求解平面连杆机构位置问题的牛顿法

从平面连杆机构的闭环矢量方程出发,介绍了求解平面连杆机构位置问题的牛顿迭代法.通过对典型平面连杆机构的分析,说明其在机构运动分析中的具体应用方法,并给出相应实例验证该方法的有效性,同时还介绍了机构运动分析中迭代初值的计算方法.     

AUTO CAD二次开发性能在机械图样绘制中的应用

绘制图样是机械制图课程学习的重要环节,直接使用AUTOCAD通用绘图软件辅助绘图,因其不具备专业绘图特点,效率不高。运用AUTOLISP开发AUTOCAD应用程序,给AUTOCAD增加新的绘图命令,从而辅助学生较快、较好地完成图样绘制。     

函数逼近理论与平面连杆机构近似综合问题的关系

针对运动几何学对平面连杆机构近似综合的不足，介绍了函数逼近理论与平面连杆机构近似综合问题的关系，为解析法进行平面四杆机构综合提供了简便的方法。     

平面四杆机构的动力学概率分析

在平面连杆机构运动学概率分析的基础上,建立了平面连杆机构动力学参数的概率分析模型,给出了平面四杆机构运动副反力的概率数字特征值计算公式,并以一简单平面铰链四杆机构介绍了此模型的使用.整个模型以矩阵形式表达,避开了对机构输出表达式直接微分时复杂的数学运算,成功地解决了机构输出参数误差的相关性问题.     

用残余位移法对二级以上平面连杆机构进行位置分析

文中利用转化机构原理对三级以上平面连杆机构的位置分析,提出了一种残余位移法。该方法只需调用二级机构位置分析的标准程序和残余位移方程求根程序,即可获得二级以上平面连杆机构位置分析的颇为满意结果。     

CAD技术在土木工程中的应用

AUTOCAD有着非常强大的绘图和编辑功能，可以方便的满足大部分绘图需要。但在完成某些特定的绘图工作时，有时就显得不太方便。一般说来，AUTOCAD的二次开发途径总体来说有两个：即文件开发和程序开发。在土木工程行业中，一般建筑物或构筑物的建设都要经过规划、设计、施工几个阶段，建成以后则进入维护管理阶段。目前，CAD技术已经被广泛应用于土木工程各个阶段。     

平面连杆机构急回特性讨论

为利用平面连杆机构的急回特性节省动力和提高劳动生产率,讨论了平面连杆机构的急回特性.运用Pro/ENGINEER对一个具体的双曲柄机构建模并进行运动仿真,找到其极位夹角,从而给出了一种验证双曲柄机构具有急回特性的方法.     

轴类零件通用CAD程序式参数化绘图研究

为提高绘图效率,本文对轴类零件为例,研究了通用CAD程序式参数化绘图的接口软件,充分利用了脚本文件和数据文件,将计算模块与绘图模块一体化,可由设计计算模块直接导入绘图模块自动绘出所需的工程图纸,实现了轴类零件的程序式参数化绘图。     

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.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…