共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
陈曦 《中国新技术新产品》2013,(23):111-111
本文分析了机械设计中零件公差的选择,探讨了机械设计中零件公差标准的适用范围与公差选用中需要注意的问题,论述了机械设计中零件公差的运用。 相似文献
3.
本文阐述了单一中径的测量方法。着重论述了螺距误差不对单一中径的测量产生影响,并给出了单一中径测量的误差公式,它不同于传统的三线法误差公式。还证实了用非理想三线测量单一中径也是可行的。最后,给出了作用中径的计算方法和实例。 相似文献
4.
《中国新技术新产品》2017,(14)
随着经济的发展,中低压农网应用范围越来越广,解决了绝大多数农村的用电问题,带动了农村经济的发展。由于中低压农网较复杂,因此施工中必须注意多种事项。本文主要介绍了中低压农网改造升级中存在的问题及原因,并提出了中低压农网改造升级中的典型经验,希望可以给同类工程提供借鉴。 相似文献
5.
6.
7.
本文分析了变电运行管理中存在的危险点及求,阐述了变电运行管理中存在的危险点类型,并及时提出了变电运行管理中危险点的防范措施。 相似文献
8.
一种无频带错位的小波包算法 总被引:5,自引:0,他引:5
研究了数字信号处理中的小波分析方法。基于多尺度分析的思想,提出了信号的小波分解及重构新算法和小波包算法。由于算法中采用了频移技术,在小波分解中避免了频率的折叠现象,同时在小波包算法中也解决了频带的错位问题。算法在工程中更具实用价值 相似文献
9.
为提高中铬铸铁共晶碳化物中M7C3比例,研究了中铬硅铸铁(290Cr8Si2).建立了铸态中铬硅铸铁基体的价电子结构,运用固体与分子经验电子理论(EET)分析了中铬硅铸铁中Si的作用.分析和实验结果表明,中铬硅铸铁基体含C、Cr、Si的γ-Fe晶胞中,C原子与Si原子的结合力强于C原子与Cr原子的结合力,较高的含Si量降低了铸铁基体的含Cr量,提高了共晶碳化物的含Cr量,进而提高了共晶碳化物中M7C3的比例.耐磨损中铬硅铸铁(290Cr8Si2)共晶碳化物(M7C3 M3C)中M7C3占94.2%(体积分数),明显高于中铬铸铁(290Cr8Si1)共晶碳化物中的M7C3的71.7%(体积分数). 相似文献
10.
研究了GCr15钢片状珠光体温变形过程中组织结构的变化。对变形中发生的变形应力随变形量增加而降低的动态软化现象进行了分析。结果表明,在温变形中,渗碳体片发生了明显的断裂,断裂的方式主要为剪切断裂和弯曲断裂,铁索体发生了动态回复,渗碳体中出现了位错的规则排列。动态软化现象主要是由于变形过程中片状渗碳体发生了断裂所造成的。 相似文献
11.
12.
《Advanced Powder Technology》2023,34(7):104058
The powder distribution and interaction between the laser beam and powder flow affect the deposition quality during the process of laser direct energy deposition with a continuous coaxial nozzle. In this paper, some key analytical formulae related to the laser beam-powder flow interaction are comprehensively deduced and validated. The powder distribution formulae for different regions are first established considering the divergence angles of powder jet. The energy attenuation formulae of laser beam passing through the powder flow are derived considering the change of powder distribution from annular to circular Gaussian modes. The temperature formulae of powder particles passing through the laser beam are derived based on a proposed temperature formula with the solid-liquid phase transition, and the powder temperature is also further analyzed. These formulae are validated by published deposition examples and used to analyze the laser beam-powder flow interaction. 相似文献
13.
A comparative analysis of various mechanisms for the generation of X-rays by relativistic particles 总被引:1,自引:0,他引:1
V.G. Baryshevsky I.D. Feranchuk 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,228(2-3):490-495
Simple formulae for the estimation of the intensity of X-rays generated by relativistic particles in various processes are found. These formulae enable us to compare the efficiency of different radiation mechanisms for obtaining quasi-monochromatic X-rays and Mössbauer gamma-rays. 相似文献
14.
水压控制爆破药量计算公式 总被引:3,自引:1,他引:2
本文分析研究了常用的九个水压爆破药量计算公式,根据十几次水压爆破的成败经验,建立了水压爆破药量计算的综合经验公式,其计算结果与实际用药量的爆破效果表明,这个公式符合得比较好。最后给出了五个实例的对比计算结果。 相似文献
15.
Formulae for Arithmetic on Genus 2 Hyperelliptic Curves 总被引:1,自引:0,他引:1
Tanja Lange 《Applicable Algebra in Engineering, Communication and Computing》2005,15(5):295-328
The ideal class group of hyperelliptic curves can be used in cryptosystems based on the discrete logarithm problem. In this article we present explicit formulae to perform the group operations for genus 2 curves. The formulae are completely general but to achieve the lowest number of operations we treat odd and even characteristic separately. We present 3 different coordinate systems which are suitable for different environments, e. g. on a smart card we should avoid inversions while in software a limited number is acceptable. The presented formulae render genus two hyperelliptic curves very useful in practice.The first system are affine coordinates where each group operation needs one inversion. Then we consider projective coordinates avoiding inversions on the cost of more multiplications and a further coordinate. Finally, we introduce a new system of coordinates and state algorithms showing that doublings are comparably cheap and no inversions are needed. A comparison between the systems concludes the paper.Acknowledgement First of all I would like to thank Gerhard Frey and Henri Cohen for encouragement and interest. Furthermore, thanks go to Roberto Avanzi for proof reading and to Bertrand Byramjee, Sylvain Duquesne, Guilhem Castagnos, and Marc Stevens for spotting some typos in the formulae of the previous papers [20, 21, 22]. I acknowledge the help of MAGMA to check the consistency of the formulae. 相似文献
16.
浅层水中爆炸冲击波压力的测试与分析 总被引:3,自引:1,他引:2
浅层水中爆炸研究是一个十分复杂的问题。本文根据对浅层水中单个球形药包爆炸的冲击波骑数的试验研究,详细地推导了分析爆炸场压力分布与变化规律的多元线性回归模型,并根据试验获得的数据给出了在试验范围内的冲击波压力的经验计算公式。 相似文献
17.
Summary Complex hypersingular (finite-part) integrals and integral equations are considered in the functional class of N. Muskhelishvili. The appropriate definition is given. Three regularization (equivalence) formulae follow from this definition. They reduce hypersingular integrals to singular ones and allow to derive hypersingular analogues for Sokhotsky-Plemelj's formulae and for conditions that are necessary and sufficient for the function to be piecewise holomorphic. Two approaches to get and investigate complex hypersingular equations follow from these results: one of them is based on the equivalence formulae; as to the other, it is based on above-mentioned conditions. As an example, authors' equation for plane elasticity is studied. The existence of a unique solution is stated and some advantages over singular equations are outlined. To solve hypersingular equations the quadrature rules are presented. The accuracy of different quadrature formulae is compared, the examples being used. They confirm the need to take into account asymptotics and to carry out a thorough analytical investigation to get safe numerical results. 相似文献
18.
《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1988,270(1):62-68
Angular distributions of radiation occuring at the passing of particles of different velocities through transparent media of different thickness have been calculated in this paper on the basis of various formulae for the intensity of the Vavilov-Cherenkov radiation (VChR) and the optical transitional radiation. In all cases, i.e. at particle velocities both above and below the VChR threshold, the angular distributions are represented as sets of maxima of different orders of K. For particle velocities above the VChR threshold there are maxima with both positive and negative K in addition to the zero (Cherenkov) maximum (K = 0). At velocities below the VChR threshold there are only maxima with positive K in the angular distributions.Comparison of the angular distributions of the radiation calculated by Tamm's formulae (for radiation within the medium) and by Pafomov's formulae (for radiation outside the medium) with the angular distributions of the transitional radiation described by the Ginsburg-Frank formulae has shown that the radiation at velocities below the VChR threshold is also transitional radiation, though not a continuous one (as in the case of particles crossing the boundary of semi-infinite media) but with maxima of different orders.This “transformed” transitional radiation accounts for the unthresholdness effect earlier found by Kobzev and Frank. 相似文献
19.
The efficiency of chillers (refrigeration and heat pump devices) is limited by the dissipation from their principal components: compressor, throttler, and heat exchangers at the condenser and evaporator. Developing a generalized finite-time thermodynamics model for reciprocating chhillers, we derive analytic formulae for how the fixed finite resources of cycle time and heat exchanger inventory should be allocated so as to optimize chiller performance. Our predictions for optimal operating schemes are compared with detailed experimental data from two different commercial chillers. The agreement between theory and actual performance data attests to the empirical wisdom that has evolved in chiller manufacture. Besides quantitatively documenting the individual sources of irreversibility, we show how the limitations of currently-available chiller components affect optimal chiller design, as well as how potentials steps to improve chiller efficiency can be evaluated within a universal thermodynamic framework. 相似文献