Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to t...Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to the macro-linear strain along the same direction. Quantitative relation between λ and microstructure parameters of the composite is obtained. As an example of applying and verifying λ, the stress-strain curve of ［AlBO］w/Al composite under tensile loading is predicted and favorably compared with experiments. By using λ, the stiffness modulus of the composite with arbitrary reinforcer orientation under any loading condition is predicted from the microstructure parameters of material.展开更多
The paper aims at providing a computerized design environment to support product design practically. The authors solved this problem by taking the product life-cycle issues into consideration as more as possible durin...The paper aims at providing a computerized design environment to support product design practically. The authors solved this problem by taking the product life-cycle issues into consideration as more as possible during the design process from the designer-oriented perspective of view. Design for X-abilities (DFX) is an effective approach to this philosophy. So the paper mainly presents the infrastructure of an intelligent DFX mechanism which is the essential part of the developed product design environment. At first the designer-oriented computer environment DesignerSpace is introduced for understanding the designer how to implement design activities and DFX method better. In order to integrate design knowledge from downstream aspects for the optimization and the design decision-making, an intelligent DFX mechanism is developed to incorporate knowledge base, algorithm-base and monitoring/debugging tools. DesignerSpace is implemented with DFX abilities and applied to the blisk design of aircraft engine and the further development is strongly intended.展开更多
This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immers...This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immersion times of 0 h(UF),3 h(AK3),6 h(AK6),9 h(AK9),and12 h(AK12).Thermogravimetric analysis(TGA)analysis shows that treated CF has higher thermal stability than CF without treatment.Cantala fiber was tested by X-ray diffraction.After alkali treatment with a 6-h soaking,it had a crystallinity index of 73.65%.Scanning electron microscopy(SEM)showed that the fibers were cleaner after alkali treatment because hemicellulose,wax,and other impurities were removed.Examination of the contact angle and surface energy showed that treated CF has smaller contact angles and greater surface energy.展开更多
Carpal coalitions are uncommon and are frequently asymptomatic. 15 Patients with persistent symptomatic scaphotrapeziotrapezoid (STT) carpal coalitions unresponsive to six months of conservative treatment with no hist...Carpal coalitions are uncommon and are frequently asymptomatic. 15 Patients with persistent symptomatic scaphotrapeziotrapezoid (STT) carpal coalitions unresponsive to six months of conservative treatment with no history of trauma went for further investigations. CT scans and bone scans revealed that coalition was the only abnormality to account for the patient’s ongoing problems. The senior authors explored the carpal coalition surgically excising the affected region and interposing capsular fibrous tissue. Histologically partial bony and cartilaginous bridging was evident with no features of degenerative arthritis being noted. Good or excellent subjective results were achieved in all patients at final review an average of 2.7 (1.0 - 4.2) years after surgery. All patients described significant reduction in visual analogue pain scores from an average of 71.5 to 18.4 points. The Green and O’Brien wrist scores improved from a mean of 58.2 to 94.2, with all patients returning to work with improved function. Normally carpal coalition is treated with arthrodesis or excision of part of the carpus. A further treatment option is outlined here with recreation of the joint space in symptomatic, isolated, nonsyndromic scaphotrapezio-trapezoidal coalition.展开更多
基金National Natural Science Foundation of China (19872 0 6 5 19732 0 6 0 ) Chinese Academy of Sciences Foundation (KJ95 1-1-2
文摘Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to the macro-linear strain along the same direction. Quantitative relation between λ and microstructure parameters of the composite is obtained. As an example of applying and verifying λ, the stress-strain curve of ［AlBO］w/Al composite under tensile loading is predicted and favorably compared with experiments. By using λ, the stiffness modulus of the composite with arbitrary reinforcer orientation under any loading condition is predicted from the microstructure parameters of material.
文摘The paper aims at providing a computerized design environment to support product design practically. The authors solved this problem by taking the product life-cycle issues into consideration as more as possible during the design process from the designer-oriented perspective of view. Design for X-abilities (DFX) is an effective approach to this philosophy. So the paper mainly presents the infrastructure of an intelligent DFX mechanism which is the essential part of the developed product design environment. At first the designer-oriented computer environment DesignerSpace is introduced for understanding the designer how to implement design activities and DFX method better. In order to integrate design knowledge from downstream aspects for the optimization and the design decision-making, an intelligent DFX mechanism is developed to incorporate knowledge base, algorithm-base and monitoring/debugging tools. DesignerSpace is implemented with DFX abilities and applied to the blisk design of aircraft engine and the further development is strongly intended.
文摘This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immersion times of 0 h(UF),3 h(AK3),6 h(AK6),9 h(AK9),and12 h(AK12).Thermogravimetric analysis(TGA)analysis shows that treated CF has higher thermal stability than CF without treatment.Cantala fiber was tested by X-ray diffraction.After alkali treatment with a 6-h soaking,it had a crystallinity index of 73.65%.Scanning electron microscopy(SEM)showed that the fibers were cleaner after alkali treatment because hemicellulose,wax,and other impurities were removed.Examination of the contact angle and surface energy showed that treated CF has smaller contact angles and greater surface energy.
文摘Carpal coalitions are uncommon and are frequently asymptomatic. 15 Patients with persistent symptomatic scaphotrapeziotrapezoid (STT) carpal coalitions unresponsive to six months of conservative treatment with no history of trauma went for further investigations. CT scans and bone scans revealed that coalition was the only abnormality to account for the patient’s ongoing problems. The senior authors explored the carpal coalition surgically excising the affected region and interposing capsular fibrous tissue. Histologically partial bony and cartilaginous bridging was evident with no features of degenerative arthritis being noted. Good or excellent subjective results were achieved in all patients at final review an average of 2.7 (1.0 - 4.2) years after surgery. All patients described significant reduction in visual analogue pain scores from an average of 71.5 to 18.4 points. The Green and O’Brien wrist scores improved from a mean of 58.2 to 94.2, with all patients returning to work with improved function. Normally carpal coalition is treated with arthrodesis or excision of part of the carpus. A further treatment option is outlined here with recreation of the joint space in symptomatic, isolated, nonsyndromic scaphotrapezio-trapezoidal coalition.
