The variations of the meltwater runoff draining from Kartamak Glacier in Mt. Muztag Ata in China were studied by using the measured hydrological data from 1 June to 25 August 2003. The meltwater runoff is mainly affec...The variations of the meltwater runoff draining from Kartamak Glacier in Mt. Muztag Ata in China were studied by using the measured hydrological data from 1 June to 25 August 2003. The meltwater runoff is mainly affected by ambient temperature and precipitation. Meltwater and precipitation samples were collected from 10 to 23 August 2003. Their pH, EC (electric conductivity) and the major ions (Na^+, K^+, Ca^(2+), Mg^(2+), Cl^-, NO_3^-, SO_~4^(2-)) were determined. pH values showed a positive correlation with EC values for all samples. Meltwater samples were slightly alkaline. Sulfate and calcium were the dominant anion and cation in the measured ions, respectively. All the ion concentrations had inverse relationships with runoff or water level. In order to discuss the origins of dissolved chemical substances in the glacial meltwater, a principal component analysis was carried out. The results showed that water-rock interaction determined the ion components of the meltwater.展开更多
In this article, the author will analyze the phenomena of soaring oil price today, how it happened, and find the reasons for the creation of OPEC, how it conducted its affairs in the market, and the economic factors t...In this article, the author will analyze the phenomena of soaring oil price today, how it happened, and find the reasons for the creation of OPEC, how it conducted its affairs in the market, and the economic factors that influenced Dr. Yamani in managing the organization effectively for a fairly long period of time to attain by the goals set out by him. I will apply the economic theories of market models, substitutability of products, the concept of price leadership etc. to explain the situation in the oil market and OPEC＇s function, which also illustrates current market behavior in the business world.展开更多
This paper presents the analysis and implementation of a synchronizer to the grid using a linear Kalman filter. The synchronizer is used in a single-phase inverter, which is applied in an environment of microgrids. Th...This paper presents the analysis and implementation of a synchronizer to the grid using a linear Kalman filter. The synchronizer is used in a single-phase inverter, which is applied in an environment of microgrids. The inverter converts the energy that comes from renewable energy sources （photovoltaic, wind, fuel cell, etc.）. The main objective of obtaining the phase of the grid is to achieve a power factor close to unity in the inverter. For this reason it is vital that the phase difference between the synchronizer and the grid zero. To obtain synchronizer algorithm using LKF （linear Kalman filter） is necessary to know the EKF （extended Kalman filter）. This allows to analyze the operation of the filter, which allows to reach reduce linear Kalman filter or also known as simplified Kalman filter. It is necessary to generate an orthogonal signal in order to obtain a stationary reference frame from a single-phase grid because the linear Kalman filter works with a stationary reference frame. Orthogonal signal is created with an all-pass filter.展开更多
基金This work was supported by the National Basic Research Program of China （Grant No.2005CB422004）；the Knowledge Innovation Project of CAS of China （Grant No. KZCX3-SW-339）；the Innovative Research Team of the National Natural Science Foundation of China （Grant No. 40121101）.
文摘The variations of the meltwater runoff draining from Kartamak Glacier in Mt. Muztag Ata in China were studied by using the measured hydrological data from 1 June to 25 August 2003. The meltwater runoff is mainly affected by ambient temperature and precipitation. Meltwater and precipitation samples were collected from 10 to 23 August 2003. Their pH, EC (electric conductivity) and the major ions (Na^+, K^+, Ca^(2+), Mg^(2+), Cl^-, NO_3^-, SO_~4^(2-)) were determined. pH values showed a positive correlation with EC values for all samples. Meltwater samples were slightly alkaline. Sulfate and calcium were the dominant anion and cation in the measured ions, respectively. All the ion concentrations had inverse relationships with runoff or water level. In order to discuss the origins of dissolved chemical substances in the glacial meltwater, a principal component analysis was carried out. The results showed that water-rock interaction determined the ion components of the meltwater.
文摘In this article, the author will analyze the phenomena of soaring oil price today, how it happened, and find the reasons for the creation of OPEC, how it conducted its affairs in the market, and the economic factors that influenced Dr. Yamani in managing the organization effectively for a fairly long period of time to attain by the goals set out by him. I will apply the economic theories of market models, substitutability of products, the concept of price leadership etc. to explain the situation in the oil market and OPEC＇s function, which also illustrates current market behavior in the business world.
文摘This paper presents the analysis and implementation of a synchronizer to the grid using a linear Kalman filter. The synchronizer is used in a single-phase inverter, which is applied in an environment of microgrids. The inverter converts the energy that comes from renewable energy sources （photovoltaic, wind, fuel cell, etc.）. The main objective of obtaining the phase of the grid is to achieve a power factor close to unity in the inverter. For this reason it is vital that the phase difference between the synchronizer and the grid zero. To obtain synchronizer algorithm using LKF （linear Kalman filter） is necessary to know the EKF （extended Kalman filter）. This allows to analyze the operation of the filter, which allows to reach reduce linear Kalman filter or also known as simplified Kalman filter. It is necessary to generate an orthogonal signal in order to obtain a stationary reference frame from a single-phase grid because the linear Kalman filter works with a stationary reference frame. Orthogonal signal is created with an all-pass filter.
