The preliminary analysis of climatic variation in China during the last 39 years has been made in this paper. The results show that although the global climate is getting warmer, some parts of China are cooling. The w...The preliminary analysis of climatic variation in China during the last 39 years has been made in this paper. The results show that although the global climate is getting warmer, some parts of China are cooling. The warming only occurs in Northeast, North and the west part of Northwest China while the areas between about 35°N and Nanling Mountain, east of the Tibetan Plateau in China are getting cooler. The cooling centers are located in Sichuan, the south part of Shaanxi and the north part of Yunnan respectively. According to the theory of greenhouse effect, there are much precipitation at low and high latitudes and less precipitation in middle latitude. However, the precipitation in the most parts of China has been decreased, especially in North and Northwest China.展开更多
On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made b...On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.展开更多
The origin of arcuate islands and deep-sea trenches has been studied for a long time and various interpretations have been proposed. In this paper, some analytical models are put forward from a geometrical viewpoint a...The origin of arcuate islands and deep-sea trenches has been studied for a long time and various interpretations have been proposed. In this paper, some analytical models are put forward from a geometrical viewpoint and then the theoretical dip angles of the underthrusting slabs of circum-Pacific island arcs are computed and compared with those of the Benioff zone. As a result, it is found that the dip angle of the underthrusting slab is one of the main factors determining the curvature of the arcuate structure. The authors consider that this result may contribute to the plate theory.展开更多
A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:The changes of ...A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:The changes of kinetic energy are mainly attributed to the generation due to non-divergent wind. During the early stage of the typhoon landing, there exits only a small quantity of kinetic energy exchanging with the environment. And after it is transformed into an extratropical cyclone, a large amount of kinetic energy is exported from the system toward the environment.The horizontal and vertical flux-divergence terms of eddy available potenlial energy are the prominent sinks in the budgets of eddy kinetic energy. The generations of eddy kinetic energy due to both the barotropic and baroclinic processes are source terms. The former is remarkable during the initial stage. But after the depression is transformed into an extratropical cyclone, the roles of the generation by the barotropic and baroclinic processes are reversed, 1. e. , the latter has become more significant than the former.Diabatic heating is the most dominant heat source. The terms of vertical heat flux by cumulus and large-scale motion are the major sinks. And the latter is prominent after the system is transformed into an extratropical cycfone.展开更多
The development and appli- cation of modern computer information and network technology is a double- edged sword. On the one hand, thanks to the rapid and convenient spread and exchange of computer- ized information a...The development and appli- cation of modern computer information and network technology is a double- edged sword. On the one hand, thanks to the rapid and convenient spread and exchange of computer- ized information and the compressed time and space on the Internet, computerized information plays a positive role in many areas like the economy, culture, education, sci- ence and technology, and politics. On the other hand, it also leads to various online rights infringements： citizens＇ individual information is revealed online; personal comput- ers are hacked; and online shopping lists are copied. Many Internet users worry about these problems to some extent. Especially in recent years, as information technology has devel- oped rapidly, people＇s online privacy rights have faced unprecedented challenges. How to strengthen pro- tection of online individual privacy has become an important challenge to the healthy development of informa- tion networks.展开更多
This paper describes procedures used for preliminary design analysis of a roll-on;roll-off passenger vessel abbreviated as RoPox. As the name presupposes, RoPax ships are used for carriage of rolling type-cargoes and ...This paper describes procedures used for preliminary design analysis of a roll-on;roll-off passenger vessel abbreviated as RoPox. As the name presupposes, RoPax ships are used for carriage of rolling type-cargoes and as well as passengers. RoPax are usually medium size ships with high performance characteristics that enhance their application for both long and short distance journeys. For instance, in Nigeria where most of her regions are surrounded by seas, this type of ship is apt. Several methods were implemented in order to obtain some preliminary results scoped in dimension, hydrostatic and hydrodynamic characteristics. The methods used correlate well with conventional values discussed in reality and in literatures.展开更多
[Objectives]The paper was to analyze the acoustic characteristics of Ips grandicollis larvae by pest acoustic detection technology,and to provide some reference for quarantine identification of pest larvae at ports.[M...[Objectives]The paper was to analyze the acoustic characteristics of Ips grandicollis larvae by pest acoustic detection technology,and to provide some reference for quarantine identification of pest larvae at ports.[Methods]The trial was performed in a self-invented insect sound recording container with good sound insulation effect.I.grandicollis larvae were placed separately on split P.ponderosa logs to observe and record the activities of larvae.AED-2010 was used for signal acquisition and SP-1 probe was used to collect signals at a distance of 5 cm from the larvae.The activity signals of larvae were intercepted,and the signal de-noising was further processed by Goldwave software.Finally,the acoustic signals were carried out correlation analysis by using MATLAB toolbox.[Results]I.grandicollis larvae had more regular feeding acoustic signal characteristics than crawling acoustic signal characteristics,and the two types of acoustic signal characteristics were quite different.The duration of feeding acoustic signal pulse of I.grandicollis larvae was 50-85 ms,the frequency was less than 1 KHz,and the signal frequency was mainly distributed in the range of 510.00-620.20 Hz.There was no obvious law in time domain features of larval crawling acoustic signals and the signal frequency was low,which was below 0.6 KHz and was mainly distributed in the range of 258.00-530.00 Hz.[Conclusions]It is feasible to carry out quarantine identification of I.grandicollis larvae by using feeding acoustic signals.It is suggested to select the feeding acoustic signals with obvious characteristics in the sound monitoring and identification of pests.展开更多
This paper investigates the optimal transfer trajectories from a circular parking orbit towards the apocenter of a rectilinear ellipse,where the spacecraft reaches a quasi-stationary condition relative to an inertial ...This paper investigates the optimal transfer trajectories from a circular parking orbit towards the apocenter of a rectilinear ellipse,where the spacecraft reaches a quasi-stationary condition relative to an inertial reference frame.The spacecraft is equipped with a propulsion system that provides a circumferential continuous propulsive acceleration,that is,an acceleration whose direction is perpendicular to the primary body-spacecraft line.The performance index to minimize is the total flight time,and an indirect method is used to analyze the transfer trajectories.In this context,the optimal transfer performance is obtained as a function of the spacecraft propulsive acceleration magnitude through an interpolation procedure of numerical simulations.The results obtained with a continuous thrust propulsion system are also compared with those derived from a multi-impulse transfer.Finally,the paper investigates a heliocentric mission scenario in which the spacecraft minimizes the flight time required to reach a rectilinear ellipse with a given value of the aphelion radius.展开更多
基金This work is supported by National Environment and Protect Agency under Program 891205
文摘The preliminary analysis of climatic variation in China during the last 39 years has been made in this paper. The results show that although the global climate is getting warmer, some parts of China are cooling. The warming only occurs in Northeast, North and the west part of Northwest China while the areas between about 35°N and Nanling Mountain, east of the Tibetan Plateau in China are getting cooler. The cooling centers are located in Sichuan, the south part of Shaanxi and the north part of Yunnan respectively. According to the theory of greenhouse effect, there are much precipitation at low and high latitudes and less precipitation in middle latitude. However, the precipitation in the most parts of China has been decreased, especially in North and Northwest China.
基金This subject is aided financially by Chinese National Natural Science Foundation.
文摘On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.
文摘The origin of arcuate islands and deep-sea trenches has been studied for a long time and various interpretations have been proposed. In this paper, some analytical models are put forward from a geometrical viewpoint and then the theoretical dip angles of the underthrusting slabs of circum-Pacific island arcs are computed and compared with those of the Benioff zone. As a result, it is found that the dip angle of the underthrusting slab is one of the main factors determining the curvature of the arcuate structure. The authors consider that this result may contribute to the plate theory.
文摘A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:The changes of kinetic energy are mainly attributed to the generation due to non-divergent wind. During the early stage of the typhoon landing, there exits only a small quantity of kinetic energy exchanging with the environment. And after it is transformed into an extratropical cyclone, a large amount of kinetic energy is exported from the system toward the environment.The horizontal and vertical flux-divergence terms of eddy available potenlial energy are the prominent sinks in the budgets of eddy kinetic energy. The generations of eddy kinetic energy due to both the barotropic and baroclinic processes are source terms. The former is remarkable during the initial stage. But after the depression is transformed into an extratropical cyclone, the roles of the generation by the barotropic and baroclinic processes are reversed, 1. e. , the latter has become more significant than the former.Diabatic heating is the most dominant heat source. The terms of vertical heat flux by cumulus and large-scale motion are the major sinks. And the latter is prominent after the system is transformed into an extratropical cycfone.
文摘The development and appli- cation of modern computer information and network technology is a double- edged sword. On the one hand, thanks to the rapid and convenient spread and exchange of computer- ized information and the compressed time and space on the Internet, computerized information plays a positive role in many areas like the economy, culture, education, sci- ence and technology, and politics. On the other hand, it also leads to various online rights infringements： citizens＇ individual information is revealed online; personal comput- ers are hacked; and online shopping lists are copied. Many Internet users worry about these problems to some extent. Especially in recent years, as information technology has devel- oped rapidly, people＇s online privacy rights have faced unprecedented challenges. How to strengthen pro- tection of online individual privacy has become an important challenge to the healthy development of informa- tion networks.
文摘This paper describes procedures used for preliminary design analysis of a roll-on;roll-off passenger vessel abbreviated as RoPox. As the name presupposes, RoPax ships are used for carriage of rolling type-cargoes and as well as passengers. RoPax are usually medium size ships with high performance characteristics that enhance their application for both long and short distance journeys. For instance, in Nigeria where most of her regions are surrounded by seas, this type of ship is apt. Several methods were implemented in order to obtain some preliminary results scoped in dimension, hydrostatic and hydrodynamic characteristics. The methods used correlate well with conventional values discussed in reality and in literatures.
基金Supported by Project of Lianyungang Science and Technology Association(Lkxqt2125)。
文摘[Objectives]The paper was to analyze the acoustic characteristics of Ips grandicollis larvae by pest acoustic detection technology,and to provide some reference for quarantine identification of pest larvae at ports.[Methods]The trial was performed in a self-invented insect sound recording container with good sound insulation effect.I.grandicollis larvae were placed separately on split P.ponderosa logs to observe and record the activities of larvae.AED-2010 was used for signal acquisition and SP-1 probe was used to collect signals at a distance of 5 cm from the larvae.The activity signals of larvae were intercepted,and the signal de-noising was further processed by Goldwave software.Finally,the acoustic signals were carried out correlation analysis by using MATLAB toolbox.[Results]I.grandicollis larvae had more regular feeding acoustic signal characteristics than crawling acoustic signal characteristics,and the two types of acoustic signal characteristics were quite different.The duration of feeding acoustic signal pulse of I.grandicollis larvae was 50-85 ms,the frequency was less than 1 KHz,and the signal frequency was mainly distributed in the range of 510.00-620.20 Hz.There was no obvious law in time domain features of larval crawling acoustic signals and the signal frequency was low,which was below 0.6 KHz and was mainly distributed in the range of 258.00-530.00 Hz.[Conclusions]It is feasible to carry out quarantine identification of I.grandicollis larvae by using feeding acoustic signals.It is suggested to select the feeding acoustic signals with obvious characteristics in the sound monitoring and identification of pests.
文摘This paper investigates the optimal transfer trajectories from a circular parking orbit towards the apocenter of a rectilinear ellipse,where the spacecraft reaches a quasi-stationary condition relative to an inertial reference frame.The spacecraft is equipped with a propulsion system that provides a circumferential continuous propulsive acceleration,that is,an acceleration whose direction is perpendicular to the primary body-spacecraft line.The performance index to minimize is the total flight time,and an indirect method is used to analyze the transfer trajectories.In this context,the optimal transfer performance is obtained as a function of the spacecraft propulsive acceleration magnitude through an interpolation procedure of numerical simulations.The results obtained with a continuous thrust propulsion system are also compared with those derived from a multi-impulse transfer.Finally,the paper investigates a heliocentric mission scenario in which the spacecraft minimizes the flight time required to reach a rectilinear ellipse with a given value of the aphelion radius.
