Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these pr...Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.展开更多
This paper proposes an analysis method of the manufactured tolerances applied to a cylinder head of car engine. This method allows to determine the manufacturing tolerances in the case of angular chains of dimensions ...This paper proposes an analysis method of the manufactured tolerances applied to a cylinder head of car engine. This method allows to determine the manufacturing tolerances in the case of angular chains of dimensions and to check its correspondence with the functional tolerances. The objective of this work is to analyze two parameterized functions: the angular defect Δα and the projected length lg of the toleranced surface. The angular defects are determined from the precision of the machine tools, we consider only the geometrical defects (position and orientation of surfaces), making the assumption that the form defects are negligible. The manufactured defect is determined from these two parameterized functions. Then it will be compared with the functional condition in order to check if the selected machining range allows, at end of the manufacturing process, to give a suitable part.展开更多
With tissue cultured-seedlings of Rhododendron chrysanthum Pall. in Changbai Mountain as test material, the effect of EMS treatment on the heat toler- ance of R. chrysanthum, as well as the possible heat tolerance mec...With tissue cultured-seedlings of Rhododendron chrysanthum Pall. in Changbai Mountain as test material, the effect of EMS treatment on the heat toler- ance of R. chrysanthum, as well as the possible heat tolerance mechanism, was in- vestigated in this study so as to lay a foundation for the popularization, application and germplasm resource innovation of R. chrysanthum. The results showed that when the leaves of the tissue cultured seedlings were treated with medium with 0.1% of EMS for 2 d, the survival rate of the leaves was 48.92%, thus the con- centration of EMS was close to the semi-lethal dose, and the EMS concentration and treatment time could be used as screening conditions for heat-tolerant mutants. The plantlets regenerated from EMS-treated leaves were treated with different tem- peratures, and related physiological indicators were determined. The results showed that the chlorophyll content, MDA content, Pro content, SOD activity, POD activity and soluble sugar content of regeneration plantlets in the treatment group were sig- nificantly different from those in the control group. At the same temperature, the chlorophyll content, soluble sugar content, Pro content, SOD activity and POD ac- tivity were significantly higher and the MDA content was significantly lower in the treatment group compared with the control. In conclusion, EMS treatment improved the heat tolerance of tissue-cultured R. chrysanthum seedlings.展开更多
文摘Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.
文摘This paper proposes an analysis method of the manufactured tolerances applied to a cylinder head of car engine. This method allows to determine the manufacturing tolerances in the case of angular chains of dimensions and to check its correspondence with the functional tolerances. The objective of this work is to analyze two parameterized functions: the angular defect Δα and the projected length lg of the toleranced surface. The angular defects are determined from the precision of the machine tools, we consider only the geometrical defects (position and orientation of surfaces), making the assumption that the form defects are negligible. The manufactured defect is determined from these two parameterized functions. Then it will be compared with the functional condition in order to check if the selected machining range allows, at end of the manufacturing process, to give a suitable part.
基金Supported by College Students’ Innovative Entrepreneurial Training Program 2016~~
文摘With tissue cultured-seedlings of Rhododendron chrysanthum Pall. in Changbai Mountain as test material, the effect of EMS treatment on the heat toler- ance of R. chrysanthum, as well as the possible heat tolerance mechanism, was in- vestigated in this study so as to lay a foundation for the popularization, application and germplasm resource innovation of R. chrysanthum. The results showed that when the leaves of the tissue cultured seedlings were treated with medium with 0.1% of EMS for 2 d, the survival rate of the leaves was 48.92%, thus the con- centration of EMS was close to the semi-lethal dose, and the EMS concentration and treatment time could be used as screening conditions for heat-tolerant mutants. The plantlets regenerated from EMS-treated leaves were treated with different tem- peratures, and related physiological indicators were determined. The results showed that the chlorophyll content, MDA content, Pro content, SOD activity, POD activity and soluble sugar content of regeneration plantlets in the treatment group were sig- nificantly different from those in the control group. At the same temperature, the chlorophyll content, soluble sugar content, Pro content, SOD activity and POD ac- tivity were significantly higher and the MDA content was significantly lower in the treatment group compared with the control. In conclusion, EMS treatment improved the heat tolerance of tissue-cultured R. chrysanthum seedlings.
