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1.
建立了金刚石削单晶锗切削力的分布模型,研究了车削单晶锗平面时表面粗糙度呈现扇形区分布特征的成因机制,并进行实验验证,采用飞切方法加工单晶锗时,可以制得表面粗糙度Ra值为0.007~0.009μm的匀质光滑表面。  相似文献   

2.
表面粗糙度的激光在线测量   总被引:3,自引:0,他引:3  
为了克服现有方法在表面粗糙度测量范围和抗震动等方面的不足,分析了最近发展起来的几种动态表面粗糙度测量方法的优缺点,提出采用被测表面激光反射图的暗区比来实现运动表面粗糙度的实时测量。该方法的测量范围可达30倍跨度,即可测量的表面粗糙度为0.05μm到1.6μm或0.4μm到12.5μm。分析了试样的运动速度和初试平均光强对暗区比的影响,该方法的测量结果与Telyer-soft表面形貌测量仪的测量结果很吻合。  相似文献   

3.
就细颗粒流化床的炉衬表面粗度对(准)散式流化状态的影响进行了试验研究。试验采用粒径为0.076 ̄0.45mm的细石墨粒子,通过变换不同的炉衬和采用自制的炉内电阻网络测量装置,得到了炉内流化滞区的分布和表面粗糙度与壁面附近流化滞区厚度的关系,并结合细颗粒与不同炉衬壁面之间的摩擦系数的测量结果,对炉衬表面粗糙度与流化滞区的关系进行了理论分析。研究表明,粗糙的炉衬表面会产生较大的流化滞区,并使流化状态过  相似文献   

4.
本文利用带料弯曲拉伸试验机、扫描电镜和表面轮廓仪等设备,探讨了模具和板材的表面粗糙度对拉深摩擦系数和工件表面质量的影响,同时研究了模具表面粗糙度对板材表面形貌的影响,磨擦系数与润滑剂粘度、拉深速度、板材表面粗糙度的三维全图关系,以及模具和板材的表面粗糙度对摩擦系数的协同作用效果.结果表明:提高润滑剂粘度和拉探速度,以及适当地提高板材表面粗糙度有利于降低磨擦,但增大模具表面粗糙度或模具与板材的表面粗糙度同时增大会加剧摩擦磨损.  相似文献   

5.
为了改善高速进给铣削加工时的表面花纹模式和降低表面粗糙度,采用切削实验和理论解析的方法,探讨了在切削过程中始终存在的刀刃相位差和回转偏心对加工表面的影响,得出如下结论:(1)垂直加工时,表面粗糙度远大于理论值,但不受刀刃相位差和回转偏心的影响;(2)倾斜加工时,刀刃相位差和回转偏心分别影响间歇进给方向和进给方向的表面花纹模式和表面粗糙度.当刀刃相位差和回转偏心约为零时,表面粗糙度接近最小值.如果再采用大的进给量,则加工面花纹以矩形形式整齐均匀排列,并且可以在不增大粗糙度的情况下大幅度提高加工效率;(3)当刀刃相位差和回转偏心大于零时,表面粗糙度有可能成倍增加.  相似文献   

6.
针阀体座面形位误差及表面粗糙度的精密测量   总被引:1,自引:0,他引:1  
研制了针阀体座面(内圆锥面)形位误差及表面粗糙度的专用测量系统,该系统由直角弯头测杆,柱面全息衍射光栅位移传感器及所浮式精密回转工作台等构成,传感器的分辨率为0.005μm;整个测量系统的精度用标准半球进行校验,测得圆度误差仅为0.163μm。  相似文献   

7.
结合剪切干涉技术与显微干涉技术,提出了显微剪切干涉非接触表面粗糙度轮廓测量方法.由于自参考干涉和共路偏振相移干涉特点,建议的干涉仪具有极好的抗环境干扰和振动的能力,同时能取得一般显微干涉仪的表面粗糙度测量精度,适合制造环境下表面粗糙度精密测量.介绍了发展的显微剪切干涉仪的原理,以及相应于粗糙度轮廓的波前重建算法.实验结果证明了该方法的可行性.  相似文献   

8.
用恒电位和动电位极化法研究了表面粗糙度对非晶态NiCrFeSiB合金亚稳态小孔形核和生长的影响,粗糙表面显著促进亚稳态小孔的形核,在恒电位下,亚稳小孔的生长电流随时间的平方线性增长为I-I0=k(t-t0)2.生长速度参数k和亚稳态小孔的峰值电流都服从对数正态分布。在粗糙表面上亚稳态小孔的生长速度略高,且分布范围较大。  相似文献   

9.
AFM研究Sol-Gel法制备的TiO_2和Al_2O_3-TiO_2-SiO_2涂膜表面形貌   总被引:1,自引:0,他引:1  
载玻片在金属醇化物的溶胶中浸涂、热处理,获得厚度为50~90nm的TiO2和XAl2O3-YTiO2-ZSiO2涂膜(X=0~30,Y=0.25~0.60,Z=0.20~0.65,摩尔分数)。使用原子力显微镜(AFM)研究涂膜表面纳米范围的形貌。研讨了化学组成,热处理温度与时间,以及热处理前或后的贮存史对表面形貌,rms-均方根粗糙度和锐钛矿结晶的影响。  相似文献   

10.
光学系统杂光分析对航天航空,精细细微分析领域的光学设计有着重要意义,其首要问题是研究光学系统中典型受光表面的散射模型。该文用小镜面细分非成像表面,结合概率论的方法,在考虑表面遮挡因子的基础上,推导了光学系统训均方粗糙度与光波波长之比〉1.0的非成像表面双向反射分布函数的数学模型,把表面特征参数与表面散射分布显式地联系起来。  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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