本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2—丙二醇(16.8%),一缩二乙二醇(15.0%),邻苯二甲酸酐(32.8%),顺丁烯...本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2—丙二醇(16.8%),一缩二乙二醇(15.0%),邻苯二甲酸酐(32.8%),顺丁烯二酸酐(21.7%),加入反应釜内,加热至100℃时,物料熔融后开始搅拌,继续升温至150℃开始控温,保持温度范围在150～160℃,展开更多
本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2一丙二醇(16.8%),一缩二乙二醇(15.0%),一缩二乙二醇(15.0%),邻苯二...本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2一丙二醇(16.8%),一缩二乙二醇(15.0%),一缩二乙二醇(15.0%),邻苯二甲酸酐(32.8%),顺丁烯二酸酐(21.7%),加入反应釜内,加热至100℃时,物料熔融后开始搅拌,继续升温至150℃开始控温。展开更多
Firstly, using the damage model for rock based on Lemaitre hypothesis about strain equivalence, a new technique for measuring strength of rock micro-cells by adopting the Mohr-Coulomb criterion was developed, and a st...Firstly, using the damage model for rock based on Lemaitre hypothesis about strain equivalence, a new technique for measuring strength of rock micro-cells by adopting the Mohr-Coulomb criterion was developed, and a statistical damage evolution equation was established based on the property that strength of micro-cells is consistent with normal distribution function, through discussing the characteristics of random distributions for strength of micro-cells, then a statistical damage constitutive model that can simulate the full process of rock strain softening under specific confining pressure was set up. Secondly, a new method to determine the model parameters which can be applied to the situations under different confining pressures was proposed, by deeply studying the relations between the model parameters and characteristic parameters of the full stress-strain curve under different confining pressures. Therefore, a unified statistical damage constitutive model for rock softening which can reflect the effect of different confining pressures was set up. This model makes the physical property of model parameters explicit, contains only conventional mechanical parameters, and leads its application more convenient. Finally, the rationality of this model and its parameters-determining method were identified via comparative analyses between theoretical and experimental curves.展开更多
The ammonia synthesis reactor is the core unit in the whole ammonia synthesis production. The ammonia concentration at the ammonia converter outlet is a significant process variable, which reflects directly the produc...The ammonia synthesis reactor is the core unit in the whole ammonia synthesis production. The ammonia concentration at the ammonia converter outlet is a significant process variable, which reflects directly the production efficiency. However, it is hard to be measured reliably online in real applications. In this paper, a soft sensor based on BP neural network (BPNN) is applied to estimate the ammonia concentration. A modified group search optimization with nearest neighborhood (GSO-NH) is proposed to optimize the weights and thresholds of BPNN. GSO-NH is integrated with BPNN to build a soft sensor model. Finally, the soft sensor model based on BPNN and GSO-NH (GSO-NH-NN) is used to infer the outlet ammonia concentration in a real-world application. Three other modeling methods are applied for comparison with GSO-NH-NN. The results show that the soft sensor based on GSO-NH-NN has a good prediction performance with high accuracy. Moreover, the GSO-NH-NN also provides good generalization ability to other modeling problems in ammonia synthesis production.展开更多
According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets： common faults and fatal faults. Common faults cause slight loss when they are ...According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets： common faults and fatal faults. Common faults cause slight loss when they are activated. A fatal fault can lead to significant loss, and even damage the safety-crltical system entirely when it is activated. A software reliability growth model for safety-critical systems is developed based on G - 0 model. And a software cost model is proposed too. The cost model considers maintenance and risk costs due to software failures. The optimal release policies are discussed to minimize the total software cost. A numerical exampie is provided to illustrate how to use the results we obtained.展开更多
文摘本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2—丙二醇(16.8%),一缩二乙二醇(15.0%),邻苯二甲酸酐(32.8%),顺丁烯二酸酐(21.7%),加入反应釜内,加热至100℃时,物料熔融后开始搅拌,继续升温至150℃开始控温,保持温度范围在150～160℃,
文摘本工艺采用化学方法合成与天然玉石、象牙、琥珀相类似特征的材料,通过软模成型可制做各种仿玉制品、工艺品。一、材料的合成1.合成仿玉 L 型树脂将乙二醇(13.7%),1,2一丙二醇(16.8%),一缩二乙二醇(15.0%),一缩二乙二醇(15.0%),邻苯二甲酸酐(32.8%),顺丁烯二酸酐(21.7%),加入反应釜内,加热至100℃时,物料熔融后开始搅拌,继续升温至150℃开始控温。
基金Project (50378036) supported by the National Natural Science Foundation of China Project (03JJY5024) supported by the Natural Science Foundation of Hunan Province, China
文摘Firstly, using the damage model for rock based on Lemaitre hypothesis about strain equivalence, a new technique for measuring strength of rock micro-cells by adopting the Mohr-Coulomb criterion was developed, and a statistical damage evolution equation was established based on the property that strength of micro-cells is consistent with normal distribution function, through discussing the characteristics of random distributions for strength of micro-cells, then a statistical damage constitutive model that can simulate the full process of rock strain softening under specific confining pressure was set up. Secondly, a new method to determine the model parameters which can be applied to the situations under different confining pressures was proposed, by deeply studying the relations between the model parameters and characteristic parameters of the full stress-strain curve under different confining pressures. Therefore, a unified statistical damage constitutive model for rock softening which can reflect the effect of different confining pressures was set up. This model makes the physical property of model parameters explicit, contains only conventional mechanical parameters, and leads its application more convenient. Finally, the rationality of this model and its parameters-determining method were identified via comparative analyses between theoretical and experimental curves.
基金Supported by the National Natural Science Foundation of China (61074079)Shanghai Leading Academic Discipline Project(B504)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education of China (20100074120010)the Natural Science Foundation of Shanghai City (11ZR1409700)
文摘The ammonia synthesis reactor is the core unit in the whole ammonia synthesis production. The ammonia concentration at the ammonia converter outlet is a significant process variable, which reflects directly the production efficiency. However, it is hard to be measured reliably online in real applications. In this paper, a soft sensor based on BP neural network (BPNN) is applied to estimate the ammonia concentration. A modified group search optimization with nearest neighborhood (GSO-NH) is proposed to optimize the weights and thresholds of BPNN. GSO-NH is integrated with BPNN to build a soft sensor model. Finally, the soft sensor model based on BPNN and GSO-NH (GSO-NH-NN) is used to infer the outlet ammonia concentration in a real-world application. Three other modeling methods are applied for comparison with GSO-NH-NN. The results show that the soft sensor based on GSO-NH-NN has a good prediction performance with high accuracy. Moreover, the GSO-NH-NN also provides good generalization ability to other modeling problems in ammonia synthesis production.
基金Sponsored by the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20020213017).
文摘According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets： common faults and fatal faults. Common faults cause slight loss when they are activated. A fatal fault can lead to significant loss, and even damage the safety-crltical system entirely when it is activated. A software reliability growth model for safety-critical systems is developed based on G - 0 model. And a software cost model is proposed too. The cost model considers maintenance and risk costs due to software failures. The optimal release policies are discussed to minimize the total software cost. A numerical exampie is provided to illustrate how to use the results we obtained.
