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1.
研究了高速滚齿滚削力与振劝的关系,切削用量及切削方式对滚削力的影响,得出结论为:滚削和的交变作用引起滚切过程的受迫振动,滚切过程的物性形自激振动条件,可通过刀具,切削用量及切削方式的合理选用防止自激振动出现,避免共振与迫振,使滚削力的变化趋于平缓。  相似文献   

2.
本文分析了无冲切钢筋混凝土板的冲切破坏形态并提出了考虑弯曲对冲切强度影响的冲切破坏模式和相应的计算公式,经与209块钢筋混凝土板的实验数据比较.说明了本文公式计算值与实验值吻合良好.  相似文献   

3.
钢筋混凝土板冲切强度的试验研究   总被引:2,自引:0,他引:2       下载免费PDF全文
在冲切强度试验的基础上,进一步分析了钢筋砼板的冲切破坏机理,认为冲切破坏是剪力与弯矩联合作用下的一种破坏形态.与破坏机理一致,本文提出了一种考虑弯曲变形影响的冲切破坏模式.应用极限平衡理论导出冲切强度理论解,计算式中体现了板面抗弯钢筋对冲切强度的作用.理论计算值与209个试验结果相比,其均值与方差分别为1.018和0.1 25.  相似文献   

4.
针对高温合金钻削困难、钻削过程中摩擦力大等问题,采用超声振动技术加工.首先,分析了超声振动减摩机理,构建了平均摩擦力与振动参数之间的关系,并得出了平均摩擦力与振幅之间的变化趋势.建立轴向超声振动钻削系统,利用该系统对高温合金进行钻削加工.结果表明:振动振幅对孔壁表面质量的影响符合超声振动钻削的减摩特性.利用优化后的振幅超声振动钻削,与普通钻削相比,切屑形态更加规整,孔壁表面粗糙度值更小,表面质量更好.  相似文献   

5.
讨论了用于研究振动钻削过程的实验研究系统,给出了由此系统所得的实验结果,此系统通过对振动钻削过程中动态切削力的采集及分析处理来研究振动钻削过程,它能够检测出切削过程中出现的异常状态,并可实现对振动钻削过程的监控.  相似文献   

6.
振动钻削中切削力的实验研究系统   总被引:1,自引:1,他引:0  
讨论了用于研究振动钻削过程的实验研究系统,给出了由此系统所得的实验结果。此系统通过对振动钻削过程中动态切削力的采集及分析处理来研究振动钻削过程,它能够检测出切削过程中出现的异常状态,并可实现对振动钻削过程的监控。  相似文献   

7.
选择钢琴音板用木材北美云杉(Picea spp.)作为研究试材,测定了云杉木材含水率为7 %时径切板的动弹性模量(E)、比动态弹性模量(E/ρ)、对数衰减率(δ)、损耗角正切(tan δ)等声学性能指标。结果表明:板厚中心线与生长轮切线之间夹角为90°的径切板,径向、弦向振动时的声学性能均优于夹角为60°的径切板;夹角为90°的径切板弦向振动时的声学性能优于径向振动时的声学性能。  相似文献   

8.
板柱结构的中柱节点传递剪力和不平衡弯矩的冲切承载力   总被引:1,自引:1,他引:1  
在《混凝土结构设计规范》(GB50010—2002)中,新增加了一节(7.7.5):在板柱结构中柱节点传递剪力和不平衡弯矩的受冲切承栽力的设计方法。然而,在国内讨论这个课题的论文很少。本文讨论了文献中报导的试验结果,阐述了板的破坏形态和特征,基于剪应力线性分布假定,推导出校核由剪力传递不平衡弯矩系数知的公式,并对试验结果作了验证,文中提出了这类构件受冲切承栽力计算方法,按此方法计算所得值与国内外试验结果的符合程度较好,文中也验证了新规范(GB50010—2002)冲切计算公式的计算值偏于安全。  相似文献   

9.
通过振动钻削实验装置,采用普通麻花钻和螺旋面钻头在不同的振动钻削参数下对高温合金和碳钢进行振动钻削实验,分析基于螺旋面钻头普通钻削和轴向振动钻削条件下不同的断屑效果.并针对钻削中轴向钻削力和扭矩进行实验研究和理论分析,研究普通麻花钻和刃磨螺旋面麻花钻对加工过程的不同影响.实验结果表明:与普通钻削所得的切屑比较,振动钻削有利于断屑,切屑体积小,排屑顺畅;复杂螺旋面振动钻削中轴向力与扭矩比普通麻花钻小,其轴向力的变化过程也比普通麻花钻平稳.  相似文献   

10.
波浪载荷与砰击载荷联合作用下SWATH船结构动态响应   总被引:1,自引:0,他引:1  
针对SWATH船特点,基于平板砰击理论,考虑砰击载荷的时变特性和空间分布不均匀性,提出了随时间和空间变化的砰击载荷公式;采用实时直接加载技术模拟波浪载荷与砰击载荷的联合作用,对某SWATH船在波浪载荷与砰击载荷联合作用下振动响应特性进行了整船数值仿真研究,讨论了砰击对结构总强度的影响. 研究发现:对于SWATH船,波浪载荷与砰击载荷联合作用有其特殊的结构响应模式. 联合作用的整体效应并不是单体船那种沿纵向的两节点弯曲振动,而是连接桥结构的横向弯曲振动;联合载荷作用对湿甲板边缘和支柱外板与横框架连接处的强度威胁较大;砰击对船体振动响应影响重大,从而影响结构总强度和总变形.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
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.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
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.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
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-  相似文献   

20.
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-  相似文献   

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