共查询到20条相似文献，搜索用时 31 毫秒
1.
This paper describes the noise mechanism of rotary vane compressor JSS -96 by the method of running independently, spectrum and the measurement of the sound intensity. The noise sources of this type compressor mainly include noise of electromotor, outlet noise and intake noise. Electromotor noise and outlet noise among them have most influence on the compressor noise. This is the further basis of noise control for rotary vane compressor. 相似文献
2.
There are two main problems in the kinematic analysisof slewing mechanism on hydraulic excavator driven by variable displace-ment pumps with total hp-control when the excavator works and it'spumps get into variable displacement state as well.The first is how todetermine the oil flow in the hydraulic system according to the sum ofthe instantaneous pressure existing both in the slewing motor and in theworking cylinder.The second is how to calculate the driving torqueacting on the mechanism according to the instantaneous pressure existingin the motor.At pressent,the methods used for the kinematic analysisof the mechanism are based upon the assumption of the mechanism to bedriven by the fixed displacement pumps or by the variable displacementpumps with individual constant hp-control.But in these ways,theproblems mentioned above cannot be solved.This paper,on the basisof the variable displacement characteristic of the pumps with totalconstant hp-control,analyses the general kinematic pattern of the slewingmechanism in detail,presents the mathematical model and the numericalmethod used for it's kinematic analysis and establishes the the basis forevaluating it's design. 相似文献
3.
LIN Yuan-hua~ 《保鲜与加工》2004,(2):24
Based on the research on the motion law of the drilling fluid along the blade, the necessary condition of the blade shape for a high efficiency turbodrill is obtained. Hence a mathematical model how to design a blade shape has been put forward, and the solution method of the model is obtained, which helps to design a high efficiency turbodrill. What's more, a 3 dimension model of the blade has been set up using Pro/E software, which can link with the advanced computer language by a interface routine and modify the 3-D blade model automatically. Based on the theory, a software has been compiled to design the blade automatically, which can improve the design efficiency and the design quality of the turbodrill. 相似文献
4.
Basing on the theory of engagement, a design has been done for a new type of counter-intermeshing twin-screw kneader. Profile of the screw includes arcs and its envelope lines, and the profile is smooth and continuous without cuspidal points. Milling cutter blade profiles also have been calculated and corrected for manufacturing the helical parts designed and getting the clearance acquired. There may be interference between the cutter and the workpiece, so interference check must be done to insure the milling cutter and screw will not be interfered. 相似文献
5.
The steering performance of vehicle is directly affected by the kinematic accuracy of steering trapezoid mechanisms. Considering uncertainties that exist in steering mechanisms, the theory of kinematic time-dependent reliability is adopted to study the analysis and synthesis of the integrated mechanisms. A new method for high accuracy actual steering mechanisms design with the uncertainties is presented. Probabilistic model of kinematic error with dimension random variable is established, and analytical models of up-crossing rate and down-crossing rate for solving the time-dependent reliability of steering mechanisms are derived. A determination model and reliability model for mechanisms synthesis are built, and a numerical example are given to verify the effectively and robustness of time-dependent reliability synthesis method. 相似文献
6.
The analysis method for profile characteristics based on Kauhunen Loeve transform is presented. The profile characteristics are represented using eigenvalues and eigenvectors, thus the error surface profile can easily be reconstructed. The main eigenvectors can be used to monitor and predict the surface error. Examples show that this method is feasible and very effective. 相似文献
7.
Due to lack of estimation during initial stage of traditional physical design process for industry product, the efficiency of conduct development is low with high cost. A basic framework of twisted blade virtual design is set up based on the theory and method of product virtual design, and aiming at the thermodynamic process of middle or lower stage of steam turbine. The molding rule of twisted blade is found by thermodynamic computation program. The study of blade virtual design is carried through from 3-dimensional modeling to simulation test. The combination of thermal power theory, computer simulation technology and CAD system forms a kind of design method with the superiority such as high efficiency, low cost and good decidability is represented in the virtual design of turbine blade. 相似文献
8.
Li Jianping Zhang Wanping Chen Tinghuai Shu Wenzhi 《保鲜与加工》1997,(2):63-68
Based on the optimal control theory and Lagrange interpolation an optimal design model of plane cascades of 3D blade in an arbitrary surface of revolution is established. Using wavelet theory to solve the model, and lots of numerical results are obtained. The results show that the wavelet method is more effective than the conventional methods. 相似文献
9.
Based on theory of cylinders subjected to uniform internal pressure, the mechanical performance of a steel tubular column filled with equidistant fiber reinforced polymer (FRP) ring stiffening concrete is investigated. The solutions for the stress and displacement are regarded as the superposition of elementary and improved solutions. The elementary solutions are found by using two dimensional elastic theory. The improved solutions are found by using the Love displacement function method. Considering the conditions of the displacement continuum of the FRP ring and the steel tube exterior, a more accurate solution for an equidistantly FRP ring stiffened cylinder subjected to a uniform internal pressure is obtained. Several numerical calculations are also carried out. The results indicate the solutions possess good convergence. 相似文献
10.
A mathematical model for accurate relief grinding of gear hob cutters along radial directions is presented based on the analysis of grinding geometry. Both the design and manufacturing models of gear hob cutters are carefully derived and presented. By employing the plane envelope theory, the reference contour of the grinding wheel is determined in order to attain the design tool profile precisely. The tooth profile error model after regrinding is also given to confirm the grinding parameters. The model provides accurate solutions for both the tool profile and the sectional contour of the grinding wheel. It is simple and straightforward and can be used to produce high precision hob cutters systematically. Two numerical examples are presented to illustrate the effectiveness of the proposed method. The model computing results indicate that the proposed method is practical, precise and reliable. The method provides valuable reference for the design and machining of hob cutters. 相似文献
11.
Higher-order elliptical bevel gear is a typical form of the noncircular bevel gear transmission.Space spherical coordinate system of the bevel gear meshing is set up based on the meshing theory of space transmission.The varying relationship among the pitch curve,tooth profile and mesh lines are analyzed,and the equation of the gear tooth surface is developed with matrix method based on space coordinate transformation.The basic parameters of the noncircular bevel gear such as transmission ratio,modulus and the number of teeth are designed,and detailed analysis of the influence of the eccentricity on the relevant parameters is carried out as well.By using discrete numerical method and three-dimensional software,the mathematical model of the tooth profile and virtual physical model of the noncircular bevel gear are established,and then simulation on its motion and interference checking are performed.Finally,the approach for design,calculation and generation of the tooth profile is obtained and its correction has been verified by experiment. 相似文献
12.
13.
3种筛选NPT-Ⅱ标记转基因油菜方法研究 总被引：1，自引：0，他引：1
利用卡那霉素溶液叶片涂抹法、种子浸泡法以及卡那霉素MS培养基筛选法三种方法对含有NPT-Ⅱ标记基因的转基因油菜种子（T0）进行筛选。结果表明,三种筛选方法的最佳卡那霉素选择压为200mg/L;涂抹叶片法4-5d可以明显识别植株对卡那霉素抗性与否,此法筛选到的4株植株PCR检测全部呈阳性,可靠性达100%;浸泡种子法2-3d可以明显识别植株对卡那霉素抗性与否,此法筛选到的5株植株PCR检测全部呈阳性,可靠性100%;MS培养基筛选法一般10d可以明显植株识别对卡那霉素抗性与否,此法筛选到20株植株,移栽后存活5株,PCR检测3株呈阳性,2株是假阳性植株,可靠性为60%。因此可以认为卡那霉素涂抹叶片和浸泡种子两种方法是转基因油菜进行大规模、快速的筛选及后代的遗传分析的理想方法。 相似文献
14.
Belt grinding machine with multi axis computer number control(CNC) system can effectively process parts with complex moulding surfaces.In this paper,iso parametric and iso planar tool path planning strategies customized for this kind of machine are proposed.The tool path generation methods are designed based on the analysis of the belt grinding process.By using least square method,optimized cross section normal is computed in the iso planar method.To improve the design efficiency of path planning,reduce experiments and increase economical benefit,the geometric simulation program based on linear grinding model is developed.Experiment on a turbine blade profile shows that the proposed algorithms work satisfyingly. 相似文献
15.
为了分析卧式青核桃脱皮机中刀片及刀片安装板等核心关键部件的结构强度和力学性能,通过设计和计算确定了刀片及刀片安装板的结构参数,采用UG三维模型软件,创建了刀片及刀片安装板的分析模型,并通过ANSYS有限元分析软件对刀片及刀片安装板进行了静力学分析和模态分析。结果表明：刀片及刀片安装板既可以实现对青核桃的输送功能,又可以实现刀片对青皮的切割作用;刀刃边缘位置的变形最大,最大值为0.509 mm;刀片折弯位置的应力和应变值最大,最大值出现在0°刀片的折弯位置,最大值为114.7 MPa;在工作过程中最大等效应力远小于材料的屈服强度,刀片及刀片安装板的模态分析前三阶固有频率分别为466.99、1 206.8、2 199.7 Hz,而机构的工作频率远小于所分析零部件的固有频率,刀片及刀片安装板的结构能够满足强度和刚度要求,且工作过程中不会出现共振问题,这为研制卧式青核桃脱皮机链板输送机构提供了理论依据。 相似文献
16.
Comparison of methods to determine the root length density of crops
In this paper, in a first step a comparison of the soil core or monolith method with the profile wall method was undertaken with data obtained for sugar beets.
Results show that differences between both methods, expressed as a factor, decline destinctly during the vegetation period. This means that the calibration of the profile wall method with the help of a time independent, average factor cannot be recommended.
In a second step, we compared the monolith method with a new procedure to estimate root growth.
Results for a soil derived from loess show that values measured and estimated correspond very well, while for a sandy soil, there was only a satisfactory correspondence.
The comparison led to the conclusion, that in field work the monolith method should be preferred to the profile wall method, and the root growth estimation procedure is available alternative to determine the root length density of cereals. 相似文献
In this paper, in a first step a comparison of the soil core or monolith method with the profile wall method was undertaken with data obtained for sugar beets.
Results show that differences between both methods, expressed as a factor, decline destinctly during the vegetation period. This means that the calibration of the profile wall method with the help of a time independent, average factor cannot be recommended.
In a second step, we compared the monolith method with a new procedure to estimate root growth.
Results for a soil derived from loess show that values measured and estimated correspond very well, while for a sandy soil, there was only a satisfactory correspondence.
The comparison led to the conclusion, that in field work the monolith method should be preferred to the profile wall method, and the root growth estimation procedure is available alternative to determine the root length density of cereals. 相似文献
17.
Based on the relation between the incipient yield pressure and the limit of yielding in cylinder according to the elastic disabled rule, a laboratorial method of determining limit of yielding of material is designed and a set of experimental data were gained by the method. The incipient yield pressure of the cylinder is gained by analyzing the experimental data, and then the limit of yielding is gained. The laboratorial method has a good reliability as the experimental value has a little error to the theory value. It has a definite engineering signification and theory value to research the mechanical capability of material and the disabled rule of high pressure vessel. 相似文献
18.
Several mathematic methods used in the numerical control system of profile followed grinding robot are described. Cubic parametric Spline surface function is employed to fit the geometric model of the surface grinded with high precision. Improvement of the physics performance of blade is obtained by reconstructing the large size surface of turbine blade based on calculation geometry. Graphic linear transfer technique is provided to users with unique format of programming. Graphic non linear transfer technique is used to solve some more difficult problems successfully including transformation of the coordinates of comtrolled points in multicoordinates system, adjustment of the attitude of grinding head as well as realization of constant pressure grinding. All these mathematics methods are demonstrated feasible and efficient in actual practice and are valuable in developing large size surface grinding robots. 相似文献
19.
采用在线监测系统监测进行随钻参数的采样与分析,建立了派生参数与直测参数的理论表达式,提出了多因素组合的地层比功模型,实现了地层地质条件与随钻参数的有机结合。以重庆市某高压变电站施工场地为依托,建立了不同地层如素填土层、粉质粘土层、砂岩层及泥岩层的地层比功演化曲线,对比地勘信息可知,不同地层的比功值存在显著差异。可见,合理的地层比功阈值是辨识地层类型的重要参量。运用统计学原理对勘测孔附近不同地层的比功值阈值进行保值优化,通过地勘获得的地层信息来验证阈值区间的可靠性。进一步采用如上地层比功阈值对该区域的其他桩位所在地层进行分析验证,说明了地层比功阈值优化的统计方法可行,其阈值区间合理,可用于其他赋存环境的地层比功阈值确定及地层识别。 相似文献
20.
ZHOU Xiao-ping~ 《保鲜与加工》2004,(1):73-76
In elastic-plastic solution of expansion of spherical cavities, based on Mohr-Coulomb strength criterion, the effect of intermediate principal stress on yield and failure of soil is not analyzed. Therefore, there is disparity between results obtained by Mohr-Coulomb strength criterion and those obtained from experimental data. In this paper, the elastic-plastic solution of expansion of spherical cavities, based on unified strength theory is established and unified solutions are obtained. The corresponding solutions of different materials can be obtained. The unified solution cannot only be used to fit the properties of the materials with different tension-pressure strength, but also those with equal tension-pressure strength. The results show that by this solution, full use of the properties of the materials can be attained to reduce supports, which is of important significance for engineering 相似文献