超声波复合振动加工机理及应用的研究

在超声波复合振动的基础上，分别对纵向振动和两种横向振动组成的Ⅰ型，Ⅱ型超声波复合振动的加工特性进行了较系统的试验研究，研究结果表明：Ⅰ型超声波复合振动可以对未烧结陶瓷等非导电脆性材料的异型孔穴，窄槽进行高效加工，而Ⅱ型超声波复合振动适用于对上述材料进行精细加工。     

复合型启裂韧度 J_(MC) 的测定方法和断裂准则的探讨

应用有限元方法和断裂实验对铝合金材料Ｌｙ１２和４０ＣｒＮｉＭｏ钢在Ⅰ＋Ⅱ型载荷下启裂韧度ＪＭＣ的测定方法及弹塑性断裂行为进行了研究，给出了２种材料复合断裂的Ｊ积分准则．结果表明：１）根据复合型ＪＲ阻力曲线，应用裂纹延伸区零扩张量法测定的不同复合比下的启裂韧度ＪＭＣ值能够满足工程精度，且简便易行；２）不同复合比下的启裂韧度ＪＭＣ值满足一定的关系式．只要能得到材料的ＪⅠＣ、ＪⅡＣ值，任何复合比下的ＪＭＣ值都可由一定的关系式计算得到．另外，得出了适用于具有较好塑韧性和中高强度材料的复合型弹塑断裂准则     

J积分断裂准则在弹塑性Ⅰ－Ⅱ复合型加载下的应用探讨

在分解Ｊ积分法调制的弹塑性大变形有限元程序计算基础上，用阻力曲线法研究了两种油井钻杆材料不同Ⅰ－Ⅱ复合比下的Ｊ积分阻力特性，结果表明：随Ⅱ型分量增加，以Ｊ积分形式表示的断裂抗力降低，提出了一个适于钻杆钢等中低强度、塑韧性较好的材料的复合型延性断裂准则：Ｊｃ＝ＪⅡｃ—（α—１）ＪⅡ（其中α为一材料常数，但在实验范围内，试样尺寸对α还有一定影响）．并结合复合延性断裂微观过程的观察，对该准则和α值做了解释和讨论。     

不锈钢,高温合金超声波振动车削试验研究

本文分析了不锈钢、高温合金的加工特性并介绍了超声波振动切削的优点。对超声波振动车削不锈钢和高温合金的表面粗糙度、表面加工硬化、切削功率以及切屑形态等进行了试验。试验结果表明,超声波振动切削不但可显著降低切削力、切削温度,而且明显改善了加工表面的质量和断屑的效果,是加工难加工材料的一种有效的方法。     

复合型启裂韧工JMC的测定方法和断裂准则的探讨

应用有限元方法和断裂实验对铝合金材料Ｌｙ１２和４０ＣｒＮｉＭｏ钢在Ⅰ＋Ⅱ型载荷下启裂韧工ＪＭＣ的测定方法及弹塑性断裂行为进行了研究，给出了２种材料复合断裂的Ｊ积分准则。结果表明：１．根据复合型ＪＲ阻力曲线，应用理解纹延伸区零扩张量法测定的不同复合比下的启裂韧度ＪＭＣ值能够满足工程精度，且简便易物；２．不同复合比下的启裂韧度ＪＭＣ值满足一定的关系式。     

超声波扭转激振镗刀镗孔工艺的实验研究

本文阐述了超声波扭转激振镗刀镗孔工艺.对超声波振动镗孔加工的规律及机理进行了探讨.这项工艺可用于难加工材料及有色金属的深孔加工.     

电磁成型加工及其实现方法研究

特种加工是不同于以往利用纯机械能的方式来进行加工的方法,在特种加工领域,采用电磁加工成型的研究还不多见,对电磁的研究多在电磁铸造等材料由液态向固态转变过程的机理和应用上进行。本文结合振动（超声波）加工技术,试图探讨一种利用电磁力进行加工成型工件的一种方法。在研究电磁加工过程能量转化基础上,讨论影响电磁成型加工方法和加工速度的因素,并在原理上提供一套电磁力与振动（超声波）加工的同步方法。     

特种加工技术在金属结合剂金刚石磨轮修整中的应用

对电火花，电解，电火花一电解复合，超声波振动等特种加工技术在金刚石磨具的修整中的应用，本文着重从各种修整办法的原理，应用范畴及国内外研究概况等方面，做了比较详细的介绍。     

澳大利亚含脂羊毛的超声波洗毛法研究

研究了超声波振动在传统非离子洗剂洗毛中的应用．实验中选用不同纤维直径的羊毛，不同冼毛时间和洗毛温度，试样经超声波振动或不经超声波振动．洗涤效果通过残脂率、纤维白度、产量和毡并率进行评估．同时使用扫描电子显微镜观察洗净毛，以评价超声波振动对纤维表面结构的影响．超声波振动处理中用较低的洗剂浓度即可达到传统洗毛过程的洗涤效果．对于细度为22μm的纤维，若用超声波洗毛法，可采用较低的洗毛温度50℃．超声波振动使洗毛过程中纤维不会产生纠缠．由于超声波振动使纤维表面变化，发生了一定程度的蚀刻．纤维的裂缝增加了40℃时含金属染料的上染速率．     

微小孔振动钻削机理研究

采用振动钻削的方法对微小孔进行钻削加工,设计制作了一台新型、高效的超声波振动钻削设备,在几种常见材料上,通过改变振动钻削参数,进行孔径为０．２￣１．０ｍｍ的粘削实验;借助扫描电镜,分析孔的表面和剖面形状,对普通钻削与振动钻削加工的孔进行了比较;从入钻过程、孔的尺寸形位精度、切屑切屑形式、孔的表面质量、钻头寿命等方面分析总结出微孔振动钻削的加工机理。     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the