Any investigation of society's historical development should begin with the fundamental issue of productivity level.The Song witnessed at least 45 new advances in production technologies,items and tools,of which a...Any investigation of society's historical development should begin with the fundamental issue of productivity level.The Song witnessed at least 45 new advances in production technologies,items and tools,of which at least 15 took place in agriculture and 30 in handicraft.Although the Song surpassed previous dynasties in overall productivity,it was also affected by a number of limitations,seven of which were particularly relevant to productivity level.With the exception of agricultural technology and firearms,the Ming and Qing failed to make major breakthroughs in the remaining five fields.Although these dynasties outperformed the Song in terms of total productivity and technology,particularly in the introduction of crops,they fell behind in productivity per capita and quality of growth,due to the population boom and the stagnation and even regression of farm technologies.Whether compared with previous dynasties or with the Ming and Qing,the Song dynasty saw the zenith of productivity development in ancient China.The level of productivity underlies Song progress and Ming and Qing stagnation,as well as the rise of Europe.展开更多
Most used products must be maintained before they are reused. The modelingmethod for maintenance design of product level reuse based on quality function deployment ispresented. A fuzzy linear optimization model is dev...Most used products must be maintained before they are reused. The modelingmethod for maintenance design of product level reuse based on quality function deployment ispresented. A fuzzy linear optimization model is developed under financial uncertainty. Objective ofthe model is to maximize improvement rate of customer satisfaction level. Maintenance cost constrainis fuzzy. The algorithm for solution to the model is given. Its optimized results not only giveattention to satisfaction degree of cost constraint, but also maximize objective value. Anillustrative example involved water bump reuse is studied and the results show that the proposedmodel can effectively help maintenance planner determine the better design scheme.展开更多
The dose-response relationship for asbestos exposure in a chrysotile product factory was studied. The past gravimetric dust concentration values, obtained from different worksites, were converted into fiber concentrat...The dose-response relationship for asbestos exposure in a chrysotile product factory was studied. The past gravimetric dust concentration values, obtained from different worksites, were converted into fiber concentration values according to conversion factors that were worked out by simultaneous sampling in this study. The conversions were made so that exposure could be expressed in fiber-years (f-yr). Asbestosis was diagnosed on the basis of chest radiographs and occupational histories. Cumulative dust exposure (f-yr) was calculated up to the date of diagnosis for asbestosis patients, and up to September 1982 for the remaining workers. A dose-response relationship expressed as fiber-years exposed vs cumulative prevalence of asbestosis was established by the life table method on the basis of these data. Predicted 3 and 1% prevalence of asbestosis corresponded to 43 and 22 f-yr exposure, respectively. Considering that a worker can work for 35 years, these doses are commensurate with dust concentrations of 1.22 and 0.63 f/ml, respectively. It is recommended that 1 f/ml be taken as the maximum allowable concentration of airborne asbestos dust for the workplace with an anticipated prevalence of about 2% asbestosis after 35 years of exposure. 1990 Academic Press, Inc.展开更多
Following the progress of satellite data assimilation in the 1990s, the combination of meteorological satellites and numerical models has changed the way scientists understand the earth. With the evolution of numerica...Following the progress of satellite data assimilation in the 1990s, the combination of meteorological satellites and numerical models has changed the way scientists understand the earth. With the evolution of numerical weather prediction models and earth system models, meteorological satellites will play a more important role in earth sciences in the future. As part of the space-based infrastructure, the Fengyun (FY) meteorological satellites have contributed to earth science sustainability studies through an open data policy and stable data quality since the first launch of the FY-1A satellite in 1988. The capability of earth system monitoring was greatly enhanced after the second-generation polar orbiting FY-3 satellites and geostationary orbiting FY-4 satellites were developed. Meanwhile, the quality of the products generated from the FY-3 and FY-4 satellites is comparable to the well-known MODIS products. FY satellite data has been utilized broadly in weather forecasting, climate and climate change investigations, environmental disaster monitoring, etc. This article reviews the instruments mounted on the FY satellites. Sensor-dependent level 1 products (radiance data) and inversion algorithm-dependent level 2 products (geophysical parameters) are introduced. As an example, some typical geophysical parameters, such as wildfires, lightning, vegetation indices, aerosol products, soil moisture, and precipitation estimation have been demonstrated and validated by in-situ observations and other well-known satellite products. To help users access the FY products, a set of data sharing systems has been developed and operated. The newly developed data sharing system based on cloud technology has been illustrated to improve the efficiency of data delivery.展开更多
As culture is the soul of a nation,the three books,＂History of Chinese Philosophy,＂＂History of Chinese Culture＂and＂History of Chinese Science and Technology＂have demonstrated the superiority of our great Chinese...As culture is the soul of a nation,the three books,＂History of Chinese Philosophy,＂＂History of Chinese Culture＂and＂History of Chinese Science and Technology＂have demonstrated the superiority of our great Chinese culture,and its significant impact in the field of international culture.Both core value and practical value of the Chinese culture are very clear,reflected in the views of universe,nature,life,health,disease,and therapy and related considerations,concepts,and technical methods.展开更多
文摘Any investigation of society's historical development should begin with the fundamental issue of productivity level.The Song witnessed at least 45 new advances in production technologies,items and tools,of which at least 15 took place in agriculture and 30 in handicraft.Although the Song surpassed previous dynasties in overall productivity,it was also affected by a number of limitations,seven of which were particularly relevant to productivity level.With the exception of agricultural technology and firearms,the Ming and Qing failed to make major breakthroughs in the remaining five fields.Although these dynasties outperformed the Song in terms of total productivity and technology,particularly in the introduction of crops,they fell behind in productivity per capita and quality of growth,due to the population boom and the stagnation and even regression of farm technologies.Whether compared with previous dynasties or with the Ming and Qing,the Song dynasty saw the zenith of productivity development in ancient China.The level of productivity underlies Song progress and Ming and Qing stagnation,as well as the rise of Europe.
基金This project is supported by National Defense Science Foundation of China(No.2001QB1014).
文摘Most used products must be maintained before they are reused. The modelingmethod for maintenance design of product level reuse based on quality function deployment ispresented. A fuzzy linear optimization model is developed under financial uncertainty. Objective ofthe model is to maximize improvement rate of customer satisfaction level. Maintenance cost constrainis fuzzy. The algorithm for solution to the model is given. Its optimized results not only giveattention to satisfaction degree of cost constraint, but also maximize objective value. Anillustrative example involved water bump reuse is studied and the results show that the proposedmodel can effectively help maintenance planner determine the better design scheme.
文摘The dose-response relationship for asbestos exposure in a chrysotile product factory was studied. The past gravimetric dust concentration values, obtained from different worksites, were converted into fiber concentration values according to conversion factors that were worked out by simultaneous sampling in this study. The conversions were made so that exposure could be expressed in fiber-years (f-yr). Asbestosis was diagnosed on the basis of chest radiographs and occupational histories. Cumulative dust exposure (f-yr) was calculated up to the date of diagnosis for asbestosis patients, and up to September 1982 for the remaining workers. A dose-response relationship expressed as fiber-years exposed vs cumulative prevalence of asbestosis was established by the life table method on the basis of these data. Predicted 3 and 1% prevalence of asbestosis corresponded to 43 and 22 f-yr exposure, respectively. Considering that a worker can work for 35 years, these doses are commensurate with dust concentrations of 1.22 and 0.63 f/ml, respectively. It is recommended that 1 f/ml be taken as the maximum allowable concentration of airborne asbestos dust for the workplace with an anticipated prevalence of about 2% asbestosis after 35 years of exposure. 1990 Academic Press, Inc.
基金This work was supported by the National Key Research and Development Program of China(2018YFB0504900,2018YFB0504905).
文摘Following the progress of satellite data assimilation in the 1990s, the combination of meteorological satellites and numerical models has changed the way scientists understand the earth. With the evolution of numerical weather prediction models and earth system models, meteorological satellites will play a more important role in earth sciences in the future. As part of the space-based infrastructure, the Fengyun (FY) meteorological satellites have contributed to earth science sustainability studies through an open data policy and stable data quality since the first launch of the FY-1A satellite in 1988. The capability of earth system monitoring was greatly enhanced after the second-generation polar orbiting FY-3 satellites and geostationary orbiting FY-4 satellites were developed. Meanwhile, the quality of the products generated from the FY-3 and FY-4 satellites is comparable to the well-known MODIS products. FY satellite data has been utilized broadly in weather forecasting, climate and climate change investigations, environmental disaster monitoring, etc. This article reviews the instruments mounted on the FY satellites. Sensor-dependent level 1 products (radiance data) and inversion algorithm-dependent level 2 products (geophysical parameters) are introduced. As an example, some typical geophysical parameters, such as wildfires, lightning, vegetation indices, aerosol products, soil moisture, and precipitation estimation have been demonstrated and validated by in-situ observations and other well-known satellite products. To help users access the FY products, a set of data sharing systems has been developed and operated. The newly developed data sharing system based on cloud technology has been illustrated to improve the efficiency of data delivery.
文摘As culture is the soul of a nation,the three books,＂History of Chinese Philosophy,＂＂History of Chinese Culture＂and＂History of Chinese Science and Technology＂have demonstrated the superiority of our great Chinese culture,and its significant impact in the field of international culture.Both core value and practical value of the Chinese culture are very clear,reflected in the views of universe,nature,life,health,disease,and therapy and related considerations,concepts,and technical methods.
