The paper gives a brief description about the current main forest fire danger rating systems in the world, which in- clude forest fire danger rating system used in Canada, USA, Australia, and other countries. It show...The paper gives a brief description about the current main forest fire danger rating systems in the world, which in- clude forest fire danger rating system used in Canada, USA, Australia, and other countries. It shows the composition, structure and development of the main fire danger rating systems. The limitations of those systems are also discussed. Through a comparison of the three main forest fire danger rating systems the paper describes their differences on development, fuel complex descriptions, inputs and outputs, and their applications and finds that the technologies of the Canadian forest fire danger rating system can be adopted for China to develop a national forest fire danger rating system. Two steps are needed to develop our own national forest fire danger rating system. Firstly, we apply the CFFDRS directly. Then some studies should be done to calibrate the FDRS to local weather and fuel characteristics.展开更多
Food is the paramount necessity of the people,and safety is most essential for food. Food safety is related to people's fundamental interests,affecting people's basic health. It is an important factor in promo...Food is the paramount necessity of the people,and safety is most essential for food. Food safety is related to people's fundamental interests,affecting people's basic health. It is an important factor in promoting people's livelihood development and social progress. Compared with European countries and the United States in developed food safety supervision systems,the development of food safety supervision system in China is still relatively backward. As food safety supervision is not in place,food safety incidents have occurred in recent years,so that public's panic about food safety has intensified. It has a strong impact on social stability and the food economy. Thus,strengthening the construction of food safety supervision system is imperative. Since experiencing a series of food safety incidents,the EU has gradually improved its food safety supervision system and has developed the most comprehensive and mature food safety supervision system in the world. On the basis of sorting out the characteristics of EU's food safety supervision system,the development direction of China's food safety supervision system is proposed from four aspects: supervisor,legal system,law enforcement ability and safety standards.展开更多
State-of-the-art technologies such as the Internet of Things(IoT),cloud computing(CC),big data analytics(BDA),and artificial intelligence(AI)have greatly stimulated the development of smart manufacturing.An important ...State-of-the-art technologies such as the Internet of Things(IoT),cloud computing(CC),big data analytics(BDA),and artificial intelligence(AI)have greatly stimulated the development of smart manufacturing.An important prerequisite for smart manufacturing is cyber-physical integration,which is increasingly being embraced by manufacturers.As the preferred means of such integration,cyber-physical systems(CPS)and digital twins(DTs)have gained extensive attention from researchers and practitioners in industry.With feedback loops in which physical processes affect cyber parts and vice versa,CPS and DTs can endow manufacturing systems with greater efficiency,resilience,and intelligence.CPS and DTs share the same essential concepts of an intensive cyber-physical connection,real-time interaction,organization integration,and in-depth collaboration.However,CPS and DTs are not identical from many perspectives,including their origin,development,engineering practices,cyber-physical mapping,and core elements.In order to highlight the differences and correlation between them,this paper reviews and analyzes CPS and DTs from multiple perspectives.展开更多
Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is mo...Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is more efficient and has a higher power density resulting in higher power MMICs and FETs.Subject to system link budgets, we usually want to run a given amplifier as close to saturation as possible to minimize CAPEX costs. Running an amplifier closer to saturation causes many non-linear effects that can cause link performance degradation and interfere with other users.To better understand and quantify the differences between GaN and GaAs amplifiers and the impact of this on system performance, some amplifier and system measurements will be taken. The findings will be documented in a white paper.展开更多
基金Supported by the Beijing Fund of Natural Science (Grant No. 6042025),China NKBRSF Project (Grant No. 2001CB409600) and the fund of Forest Protection Laboratory,State Forestry Administration
文摘The paper gives a brief description about the current main forest fire danger rating systems in the world, which in- clude forest fire danger rating system used in Canada, USA, Australia, and other countries. It shows the composition, structure and development of the main fire danger rating systems. The limitations of those systems are also discussed. Through a comparison of the three main forest fire danger rating systems the paper describes their differences on development, fuel complex descriptions, inputs and outputs, and their applications and finds that the technologies of the Canadian forest fire danger rating system can be adopted for China to develop a national forest fire danger rating system. Two steps are needed to develop our own national forest fire danger rating system. Firstly, we apply the CFFDRS directly. Then some studies should be done to calibrate the FDRS to local weather and fuel characteristics.
文摘Food is the paramount necessity of the people,and safety is most essential for food. Food safety is related to people's fundamental interests,affecting people's basic health. It is an important factor in promoting people's livelihood development and social progress. Compared with European countries and the United States in developed food safety supervision systems,the development of food safety supervision system in China is still relatively backward. As food safety supervision is not in place,food safety incidents have occurred in recent years,so that public's panic about food safety has intensified. It has a strong impact on social stability and the food economy. Thus,strengthening the construction of food safety supervision system is imperative. Since experiencing a series of food safety incidents,the EU has gradually improved its food safety supervision system and has developed the most comprehensive and mature food safety supervision system in the world. On the basis of sorting out the characteristics of EU's food safety supervision system,the development direction of China's food safety supervision system is proposed from four aspects: supervisor,legal system,law enforcement ability and safety standards.
基金This work is financially supported by the National Key Research and Development Program of China(2016YFB1101700)the National Natural Science Foundation of China(51875030)the Academic Excellence Foundation of BUAA for PhD Students.
文摘State-of-the-art technologies such as the Internet of Things(IoT),cloud computing(CC),big data analytics(BDA),and artificial intelligence(AI)have greatly stimulated the development of smart manufacturing.An important prerequisite for smart manufacturing is cyber-physical integration,which is increasingly being embraced by manufacturers.As the preferred means of such integration,cyber-physical systems(CPS)and digital twins(DTs)have gained extensive attention from researchers and practitioners in industry.With feedback loops in which physical processes affect cyber parts and vice versa,CPS and DTs can endow manufacturing systems with greater efficiency,resilience,and intelligence.CPS and DTs share the same essential concepts of an intensive cyber-physical connection,real-time interaction,organization integration,and in-depth collaboration.However,CPS and DTs are not identical from many perspectives,including their origin,development,engineering practices,cyber-physical mapping,and core elements.In order to highlight the differences and correlation between them,this paper reviews and analyzes CPS and DTs from multiple perspectives.
文摘Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is more efficient and has a higher power density resulting in higher power MMICs and FETs.Subject to system link budgets, we usually want to run a given amplifier as close to saturation as possible to minimize CAPEX costs. Running an amplifier closer to saturation causes many non-linear effects that can cause link performance degradation and interfere with other users.To better understand and quantify the differences between GaN and GaAs amplifiers and the impact of this on system performance, some amplifier and system measurements will be taken. The findings will be documented in a white paper.
