作者: Ming Yu Huang, Jing Jing Lv, Hong Jun Ni, Yu Zhu, Fu Bao Zhang

摘要: A lot of peptides were synthesized on the basis of the sequence of αs1-casein. These tri-peptides with the characteristics of low toxicity and high biological activity will be applied to screen a new type of antihypertensive drug. Angiotensin-converting enzyme inhibitors (ACEI) with the better biological activity were screened and their structure-activity relationship was studied. The method of Fmoc solid-phase synthesis had been used to synthesize tri-peptides, and the principle, species, steps of which had been introduced respectively. HPLC assay was applied to screen the activity of ACEI by detecting the concentrate of hippuric acid, which can correspond with the inhibitory activity of tri-peptides. The results showed that the tri-peptides containing hydrophobic amino acid or praline had higher inhibition activity, and the same to the one that containing an aromatic amino acid in N-terminal.

253

作者: Xiao Wei Zhang, Xing Hua Li, Bo Chen

摘要: In this paper, the mathematical model with errors for parallel double-joint coordinate measuring machine (CMM) was proposed. The main factor of the impact of circular grating measurement error--radial install eccentric error--was analyzed. The error was measured and the data obtained from measurement was used to curve fitting and form the error compensation formula. Experiments show that the method of error compensation has good usability and accuracy.

1899

作者: Fang Li, Shu Gui Liu, Lei Zhao

摘要: A new 5-DOF flexible coordinate measuring machine (CMM) is introduced in this paper, which uses REVO system produced by Renishaw. According to the D-H method, the mathematical model is built, and then the error model of the flexible CMM is derived. The parameter calibration based on the nonlinear least square method is analyzed theoretically. Due to the disadvantages of Gauss-Newton method, LM method is researched, which improved the singularity of the coefficient matrix. The calibration analysis is a basis for improving accuracy of the flexible CMM.

3273

作者: Yuan Rui Zhang, Jiang Zhu, Tomohisa Tanaka, Yoshio Saito

摘要: In this study, a small, 6-DOF (degree of freedom) parallel mechanism worktable for machine tool was developed. There are a lot of factors that affect the positioning error and the accuracy of the machine tools. The uncertainty in position is mainly due to the rigidity of the structure, the geometric error of parts and assembly errors. It is very difficult to estimate the assembly errors and the link parameter of each part. In this paper, the uncertainty factor in positioning of the worktable was investigated and compensated based on measurement of movement error by using coordinate measuring machine (CMM).

463

作者: Hai Tao Li, Wen Jun Wei, Xue Zhu Dong

摘要: In order to examine and evaluate the characteristics of a mechanical component, a 3-dimensional curve on the surface of the component needs to be measured on a coordinate measuring machine (CMM). A method of measuring a 3-dimensional curve on a surface with a CMM was put forward in this paper. The measuring method of each point of the curve on the surface is divided into three steps. The first step is to select some grid points of the surface near the measured point of the curve. Actually the measuring results are the coordinates of the center of the spherical probe and all of the grid points locate in the offset surface of the measured surface. So the probe radius should be compensated. In order to make the compensation reliable, easy and simply, some regular grid points where the probe center should be set are selected and a corresponding method of calculating the normal vector of the surface is used. A small surface patch of the actual surface is measured in the second step. In the last step, some new grid points are obtained after probe radius compensation. The real coordinates of the measured point is determined by using the interpolation method and the theoretical equation of the curve. The measuring method was used to examine the modification curve of a worm generated by linear cutter edge with two degrees of freedom and the results showed the coherence of the actual modification curve to the theoretical one.

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