In light of economic globalization and the international economic landscape that has been changed by the global financial crisis,China's economy has already been completely integrated into the global economy.The C...In light of economic globalization and the international economic landscape that has been changed by the global financial crisis,China's economy has already been completely integrated into the global economy.The Chinese enterprises face fierce competition not only internationally as they pursue a "going global" strategy,but also in the domestic market from foreign companies.Therefore,to make their business operations international is not an option,but a must.Entergrises must cultivate international strategic thinking and an international vision,learn to use international resourcrs and markets,optimize resource distribution,develop advantages,and raise their core competiveness.展开更多
Aerospace microelectronic technology has become the core competence of aerospace technology. For evaluating the aerospace microelectronic industry, it is necessary to change descriptive language of goal to quantitativ...Aerospace microelectronic technology has become the core competence of aerospace technology. For evaluating the aerospace microelectronic industry, it is necessary to change descriptive language of goal to quantitative index that can be measured. Knowing quantified goals or tree structure and array of general goal system, with certain algorithm and processing each corresponding list or array, we can bring out a quantified general goal value. The multi-objective (multi-attribute) evaluation method and the relevant weight sum algorithm have been adopted to quantitatively evaluate and forecast the developing state of the industry. A practical example illustrates that the applied decision technique and the algorithm are feasible and effective.展开更多
Aerospace product development and manufacturing are key components of the air transport system. At national levels in developed countries, the aerospace industry is considered as a highly strategic sector. A solid nat...Aerospace product development and manufacturing are key components of the air transport system. At national levels in developed countries, the aerospace industry is considered as a highly strategic sector. A solid national aerospace industry is therefore a symbol of strength. Countries are pragmatic: the positive impact of a well-developed transportation network on economic growth is indubitable and civil aircraft production is a key element of this network. Countries may also assert their sovereignty by being recognized players in the defence segment of aerospace. This paper will look at the cases of France and Quebec where local governments have invested significant public funding in poles of competitiveness (in the case of France) and clusters (in the case of Quebec). While our examination of the France and Quebec aerospace scenes reveals a surprisingly large number of groupings, it does not indicate that all their members, large and small, equally benefit from participating in them. In this thick institutional environment, aerospace clusters and poles of competitiveness may compete against each other and become self-serving rather than representing and promoting their members.展开更多
Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high ...Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high power components.In this paper we report a novel approach to realize an effective increase in the multipaction threshold by employing micro-porous surfaces.Two micro-porous structures,i.e.,a regular micro-porous array fabricated by photolithography pattern processing and an irregular micro-porous array fabricated by a direct chemical etching technique,are proposed for suppressing the secondary electron yield(SEY) and multipaction in components,and the benefits are validated both theoretically and experimentally.These surface processing technologies are compatible with the metal plating process,and offer substantial flexibility and accuracy in topology design.The suppression effect is quantified for the first time through the proper fitting of the surface morphology and the corresponding secondary emission properties.Insertion losses when using these structures decrease dramatically compared with regular millimeter-scale structures on high power dielectric windows.SEY tests on samples show that the maximum yield of Ag-plated samples is reduced from 2.17 to 1.58 for directly chemical etched samples.Multipaction testing of actual C-band impedance transformers shows that the discharge thresholds of the processed components increase from 2100 W to 5500 W for photolithography pattern processing and 7200 W for direct chemical etching,respectively.Insertion losses increase from 0.13 d B to only 0.15 d B for both surface treatments in the transmission band.The experimental results agree well with the simulation results,which offers great potential in the quantitative anti-multipaction design of high power microwave components for space applications.展开更多
Liquid propellant rocket engines for a launch vehicle are an essential aerospace technology, representing the advanced level of hi-tech in a country. In recent years, China’s aerospace industry has made remarkable ac...Liquid propellant rocket engines for a launch vehicle are an essential aerospace technology, representing the advanced level of hi-tech in a country. In recent years, China’s aerospace industry has made remarkable achievements, and liquid rocket engine technology has also been effectively developed. In this article, the development processes of China’s liquid rocket engines are discussed. Then, the performance features of China’s new generation liquid rocket engines as well as the flight tests of the new-generation launch vehicles are introduced. Finally, the development direction and the most recent progress of the next generation large-thrust liquid rocket engine is presented.展开更多
This paper studies the factors affecting the technology-transfer within international research and development (R&D) networks. Specifically, this study examines the characteristics of ties, actors, and internationa...This paper studies the factors affecting the technology-transfer within international research and development (R&D) networks. Specifically, this study examines the characteristics of ties, actors, and international network configuration to assess finn's accessibility to unique technologies. This study was conducted by research analysis in the aerospace industry. The total sample size used in this study is 125 cases of international R&D consortiums from January 1980 to December 2000. The result of this study supports the effects of "strength of tie" and "characteristic of actors" on the technology transfer explained by network theory. It also demonstrates that the international network structure that would facilitate the technology transfer is shaped by dual type of tie; the apparent type of tie is general, usual, and functional tie, and the hidden one is the national culture.展开更多
The mobile hybrid machining robot has a very bright application prospect in the field of high-efficiency and high-precision machining of large aerospace structures.However,an inappropriate base placement may make the ...The mobile hybrid machining robot has a very bright application prospect in the field of high-efficiency and high-precision machining of large aerospace structures.However,an inappropriate base placement may make the robot encounter a singular configuration,or even fail to complete the entire machining task due to unreachability.In addition to considering the two constraints of reachability and non-singularity,this paper also optimizes the robot base placement with stiffness as the goal to improve the machining quality.First of all,starting from the structure of the robot,the reachability and nonsingularity constraints are transformed into a simple geometric constraint imposed on the base placement:feasible base placement area.Then,genetic algorithm is used to search for the base placement with near optimal stiffness(near optimal base placement for short)in the feasible base placement area.Finally,multiple controlled experiments were carried out by taking the milling of a protuberance on the spacecraft cabin as an example.It is found that the calculated optimal base placement meets all the constraints and that the machining quality was indeed improved.In addition,compared with simple genetic algorithm,it is proved that the feasible base placement area method can shorten the running time of the whole program.展开更多
文摘In light of economic globalization and the international economic landscape that has been changed by the global financial crisis,China's economy has already been completely integrated into the global economy.The Chinese enterprises face fierce competition not only internationally as they pursue a "going global" strategy,but also in the domestic market from foreign companies.Therefore,to make their business operations international is not an option,but a must.Entergrises must cultivate international strategic thinking and an international vision,learn to use international resourcrs and markets,optimize resource distribution,develop advantages,and raise their core competiveness.
文摘Aerospace microelectronic technology has become the core competence of aerospace technology. For evaluating the aerospace microelectronic industry, it is necessary to change descriptive language of goal to quantitative index that can be measured. Knowing quantified goals or tree structure and array of general goal system, with certain algorithm and processing each corresponding list or array, we can bring out a quantified general goal value. The multi-objective (multi-attribute) evaluation method and the relevant weight sum algorithm have been adopted to quantitatively evaluate and forecast the developing state of the industry. A practical example illustrates that the applied decision technique and the algorithm are feasible and effective.
文摘Aerospace product development and manufacturing are key components of the air transport system. At national levels in developed countries, the aerospace industry is considered as a highly strategic sector. A solid national aerospace industry is therefore a symbol of strength. Countries are pragmatic: the positive impact of a well-developed transportation network on economic growth is indubitable and civil aircraft production is a key element of this network. Countries may also assert their sovereignty by being recognized players in the defence segment of aerospace. This paper will look at the cases of France and Quebec where local governments have invested significant public funding in poles of competitiveness (in the case of France) and clusters (in the case of Quebec). While our examination of the France and Quebec aerospace scenes reveals a surprisingly large number of groupings, it does not indicate that all their members, large and small, equally benefit from participating in them. In this thick institutional environment, aerospace clusters and poles of competitiveness may compete against each other and become self-serving rather than representing and promoting their members.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1537211)the National Key Laboratory Key Foundation,China(Grant No.9140C530101150C53011)China Postdoctoral Science Foundation(Grant No.2015M572661XB)
文摘Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high power components.In this paper we report a novel approach to realize an effective increase in the multipaction threshold by employing micro-porous surfaces.Two micro-porous structures,i.e.,a regular micro-porous array fabricated by photolithography pattern processing and an irregular micro-porous array fabricated by a direct chemical etching technique,are proposed for suppressing the secondary electron yield(SEY) and multipaction in components,and the benefits are validated both theoretically and experimentally.These surface processing technologies are compatible with the metal plating process,and offer substantial flexibility and accuracy in topology design.The suppression effect is quantified for the first time through the proper fitting of the surface morphology and the corresponding secondary emission properties.Insertion losses when using these structures decrease dramatically compared with regular millimeter-scale structures on high power dielectric windows.SEY tests on samples show that the maximum yield of Ag-plated samples is reduced from 2.17 to 1.58 for directly chemical etched samples.Multipaction testing of actual C-band impedance transformers shows that the discharge thresholds of the processed components increase from 2100 W to 5500 W for photolithography pattern processing and 7200 W for direct chemical etching,respectively.Insertion losses increase from 0.13 d B to only 0.15 d B for both surface treatments in the transmission band.The experimental results agree well with the simulation results,which offers great potential in the quantitative anti-multipaction design of high power microwave components for space applications.
文摘Liquid propellant rocket engines for a launch vehicle are an essential aerospace technology, representing the advanced level of hi-tech in a country. In recent years, China’s aerospace industry has made remarkable achievements, and liquid rocket engine technology has also been effectively developed. In this article, the development processes of China’s liquid rocket engines are discussed. Then, the performance features of China’s new generation liquid rocket engines as well as the flight tests of the new-generation launch vehicles are introduced. Finally, the development direction and the most recent progress of the next generation large-thrust liquid rocket engine is presented.
文摘This paper studies the factors affecting the technology-transfer within international research and development (R&D) networks. Specifically, this study examines the characteristics of ties, actors, and international network configuration to assess finn's accessibility to unique technologies. This study was conducted by research analysis in the aerospace industry. The total sample size used in this study is 125 cases of international R&D consortiums from January 1980 to December 2000. The result of this study supports the effects of "strength of tie" and "characteristic of actors" on the technology transfer explained by network theory. It also demonstrates that the international network structure that would facilitate the technology transfer is shaped by dual type of tie; the apparent type of tie is general, usual, and functional tie, and the hidden one is the national culture.
基金supported by National Natural Science Foundation of China(Nos.91948301,52175025 and 51721003).
文摘The mobile hybrid machining robot has a very bright application prospect in the field of high-efficiency and high-precision machining of large aerospace structures.However,an inappropriate base placement may make the robot encounter a singular configuration,or even fail to complete the entire machining task due to unreachability.In addition to considering the two constraints of reachability and non-singularity,this paper also optimizes the robot base placement with stiffness as the goal to improve the machining quality.First of all,starting from the structure of the robot,the reachability and nonsingularity constraints are transformed into a simple geometric constraint imposed on the base placement:feasible base placement area.Then,genetic algorithm is used to search for the base placement with near optimal stiffness(near optimal base placement for short)in the feasible base placement area.Finally,multiple controlled experiments were carried out by taking the milling of a protuberance on the spacecraft cabin as an example.It is found that the calculated optimal base placement meets all the constraints and that the machining quality was indeed improved.In addition,compared with simple genetic algorithm,it is proved that the feasible base placement area method can shorten the running time of the whole program.