The hyperspectral reflectance of the canopy and the leaves on the main stemfor six varieties, two each of rice corn, and cotton crops, were measured at different growth stageswith an ASD FieldSpec Pro FR^(TM) to analy...The hyperspectral reflectance of the canopy and the leaves on the main stemfor six varieties, two each of rice corn, and cotton crops, were measured at different growth stageswith an ASD FieldSpec Pro FR^(TM) to analyze red edge characteristics forleaf area indices (LAI),aboveground biomass, as well as the chlorophyll, carotenoid, and nitrogen content, emphasizingcomparative differences on the red edge parameters. The results showed a 'double peak' phenomenonfor the red edge of the canopy spectra but not for the leaves. There were 'increase' and 'decrease'change rules for the red edge position, lambda_r, the red edge slope, D lambda_r, and the red edgearea, S_r, of the canopy spectra for all 3 crops with a 'blue shift' for lambda_r of the leafspectra for all 3 crops as the development stages progressed. For rice, corn, and cotton the LAI andfresh leaf mass had highly significant correlations (P < 0.01) to the red edge parameters lambda_r,D lambda_r, and S_r of their canopy spectra. Additionally, for all crops the chlorophyll-a,chlorophyll-b, total chlorophyll, and carotenoid content of the leaves all had highly significant (P< 0.01) correlations to their lambda_r. For rice, the nitrogen content of the leaves in g kg^(-1)and phytomassfor a unit area of land in g m^(-2) also had a highly significant (P < 0.01)correlation to lambda_r, D lambda_r lambda_r, and S_r of the canopy spectra.展开更多
Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound so...Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound source without exact orientation, this method horizontally rotates the array exactly once, performs eigen value decomposition for the covariance matrix of received data, then computes the gain and phase error according to the formulas. In the near field, using the same single sound source, it is necessary to rotate the array horizontally at most three times, build equations according to geometric relations, then solve them. Using the formula proposed in this paper, spherical waves are modified into plane waves. Then eigen values decomposition is performed. These two calibration methods were shown to be valid by simulation and are fast, accurate and easy to use. Finally, an analysis of factors influencing estimation precision is given.展开更多
To efficiently exploit the performance of single instruction multiple data （SIMD） architectures for video coding, a parallel memory architecture with power-of-two memory modules is proposed. It employs two novel ske...To efficiently exploit the performance of single instruction multiple data （SIMD） architectures for video coding, a parallel memory architecture with power-of-two memory modules is proposed. It employs two novel skewing schemes to provide conflict-free access to adjacent elements （8-bit and 16-bit data types） or with power-of-two intervals in both horizontal and vertical directions, which were not possible in previous parallel memory architectures. Area consumptions and delay estimations are given respectively with 4, 8 and 16 memory modules. Under a 0.18-pm CMOS technology, the synthesis results show that the proposed system can achieve 230 MHz clock frequency with 16 memory modules at the cost of 19k gates when read and write latencies are 3 and 2 clock cycles, respectively. We implement the proposed parallel memory architecture on a video signal processor （VSP）. The results show that VSP enhanced with the proposed architecture achieves 1.28× speedups for H.264 real-time decoding.展开更多
This paper aims to examine the existence of calendar anomalies including month-of-year effect, turn-of-month effect, and weekend effect in Thai stock market. The stock return is computed from SET index during 1988 to ...This paper aims to examine the existence of calendar anomalies including month-of-year effect, turn-of-month effect, and weekend effect in Thai stock market. The stock return is computed from SET index during 1988 to 2009 and the SET50 index gathered since it was created in 1995. The unit root test is performed to ensure that the stock return series have no unit root. The multiple regression techniques using dummy variables are employed to test the difference of the return during each calendar anomalies period. If the regression model suffers from conditional heteroskedasticity, the GARCH （1, 1） model will be used instead of normal ordinary least square regression. It was found that the calendar anomalies exist in Thai stock market. The return is abnormally high during December and January, which can be addressed to be the turn-of-year effect. The return during the turn-of-month period, which can be defined as the last trading day and the first four trading days of the following months, is also abnormally high. Finally, the return is also abnormally high on Fridays but abnormally low on Mondays, which is addressed as weekend effect. This may create the opportunity to make above-average profit to investors exploiting these calendar anomalies. Although these calendar anomalies may be difficult to be exploited in practice because of transaction costs and ability to replicate the stock index, the existing evidence of calendar anomalies can help investors as the clue for the timing of investment.展开更多
The satisfactory performance of electrical equipments depends on their operating temperature. In order to maintain these devices within the safe temperature limits, an effective cooling is needed. High heat transfer r...The satisfactory performance of electrical equipments depends on their operating temperature. In order to maintain these devices within the safe temperature limits, an effective cooling is needed. High heat transfer rate of compact in size and reliable operation are the challenges of a thermal design engineer of electronic equipment. Then, it has been simulated the transient a three-dimensional model to study the heating phenomenon with two assumption values of heat generation. To control for the working of this equipment, cooling process was modeled by choosing one from different cooling technique. Constant low speed fan at one direction of air flow was used for cooling to predict the reducing of heating temperature through working of this equipment. Numerical Solution of finite difference time domain method （FDTD） has been utilized to simulate the temporal and spatial temperature profiles through two processes, which would minimize the solution errors.展开更多
Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-dev...Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-developed software Position And Navigation Data Analysis(PANDA) and Beidou Experimental Tracking Stations (BETS),which are built by Wuhan University,the study of Beidou precise orbit determination,static precise point positioning (PPP),and high precision relative positioning,and differential positioning are carried out comprehensively.Results show that the radial precision of the Beidou satellite orbit determination is better than 10 centimeters.The RMS of static PPP can reach several centimeters to even millimeters for baseline relative positioning.The precision of kinematic pseudo-range differential positioning and RTK mode positioning are 2-4 m and 5-10 cm respectively,which are close to the level of GPS precise positioning.Research in this paper verifies that,with support of ground reference station network,Beidou satellite navigation system can provide precise positioning from several decimeters to meters in the wide area and several centimeters in the regional area.These promising results would be helpful for the implementation and applications of Beidou satellite navigation system.展开更多
Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation so...Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation sources and then extracting the lightning channel,it can accurately obtain the length of the channel.To validate the feasibility of the approach,a simulation experiment is designed,and it shows the length error is no more than 10%.The relationship between the NO production of per unit arc length and atmospheric pressure obtained in laboratory is applied to the NOX production of per unit flash length at different altitudes in this paper.The channel length and the NOX production of 11 negative cloud-to-ground flashes and 59 intracloud flashes in an isolated thunderstorm in the northeastern Qinghai-Tibet Plateau are calculated.The results show that the average channel lengths of per cloud-to-ground and intracloud flash are 28.9 and 22.3 km respectively;the average NOX productions of per cloud-to-ground and intracloud flash are 1.89×1025 and 0.42×1025 molecules,respectively.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 40171065 and 40271078) the National '863' Project of China (Nos. 2002AA243011 and 2002AA130010).
文摘The hyperspectral reflectance of the canopy and the leaves on the main stemfor six varieties, two each of rice corn, and cotton crops, were measured at different growth stageswith an ASD FieldSpec Pro FR^(TM) to analyze red edge characteristics forleaf area indices (LAI),aboveground biomass, as well as the chlorophyll, carotenoid, and nitrogen content, emphasizingcomparative differences on the red edge parameters. The results showed a 'double peak' phenomenonfor the red edge of the canopy spectra but not for the leaves. There were 'increase' and 'decrease'change rules for the red edge position, lambda_r, the red edge slope, D lambda_r, and the red edgearea, S_r, of the canopy spectra for all 3 crops with a 'blue shift' for lambda_r of the leafspectra for all 3 crops as the development stages progressed. For rice, corn, and cotton the LAI andfresh leaf mass had highly significant correlations (P < 0.01) to the red edge parameters lambda_r,D lambda_r, and S_r of their canopy spectra. Additionally, for all crops the chlorophyll-a,chlorophyll-b, total chlorophyll, and carotenoid content of the leaves all had highly significant (P< 0.01) correlations to their lambda_r. For rice, the nitrogen content of the leaves in g kg^(-1)and phytomassfor a unit area of land in g m^(-2) also had a highly significant (P < 0.01)correlation to lambda_r, D lambda_r lambda_r, and S_r of the canopy spectra.
文摘Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound source without exact orientation, this method horizontally rotates the array exactly once, performs eigen value decomposition for the covariance matrix of received data, then computes the gain and phase error according to the formulas. In the near field, using the same single sound source, it is necessary to rotate the array horizontally at most three times, build equations according to geometric relations, then solve them. Using the formula proposed in this paper, spherical waves are modified into plane waves. Then eigen values decomposition is performed. These two calibration methods were shown to be valid by simulation and are fast, accurate and easy to use. Finally, an analysis of factors influencing estimation precision is given.
基金Project (No. 2005AA1Z1271) supported by the Hi-Tech Research and Development Program (863) of China
文摘To efficiently exploit the performance of single instruction multiple data （SIMD） architectures for video coding, a parallel memory architecture with power-of-two memory modules is proposed. It employs two novel skewing schemes to provide conflict-free access to adjacent elements （8-bit and 16-bit data types） or with power-of-two intervals in both horizontal and vertical directions, which were not possible in previous parallel memory architectures. Area consumptions and delay estimations are given respectively with 4, 8 and 16 memory modules. Under a 0.18-pm CMOS technology, the synthesis results show that the proposed system can achieve 230 MHz clock frequency with 16 memory modules at the cost of 19k gates when read and write latencies are 3 and 2 clock cycles, respectively. We implement the proposed parallel memory architecture on a video signal processor （VSP）. The results show that VSP enhanced with the proposed architecture achieves 1.28× speedups for H.264 real-time decoding.
文摘This paper aims to examine the existence of calendar anomalies including month-of-year effect, turn-of-month effect, and weekend effect in Thai stock market. The stock return is computed from SET index during 1988 to 2009 and the SET50 index gathered since it was created in 1995. The unit root test is performed to ensure that the stock return series have no unit root. The multiple regression techniques using dummy variables are employed to test the difference of the return during each calendar anomalies period. If the regression model suffers from conditional heteroskedasticity, the GARCH （1, 1） model will be used instead of normal ordinary least square regression. It was found that the calendar anomalies exist in Thai stock market. The return is abnormally high during December and January, which can be addressed to be the turn-of-year effect. The return during the turn-of-month period, which can be defined as the last trading day and the first four trading days of the following months, is also abnormally high. Finally, the return is also abnormally high on Fridays but abnormally low on Mondays, which is addressed as weekend effect. This may create the opportunity to make above-average profit to investors exploiting these calendar anomalies. Although these calendar anomalies may be difficult to be exploited in practice because of transaction costs and ability to replicate the stock index, the existing evidence of calendar anomalies can help investors as the clue for the timing of investment.
文摘The satisfactory performance of electrical equipments depends on their operating temperature. In order to maintain these devices within the safe temperature limits, an effective cooling is needed. High heat transfer rate of compact in size and reliable operation are the challenges of a thermal design engineer of electronic equipment. Then, it has been simulated the transient a three-dimensional model to study the heating phenomenon with two assumption values of heat generation. To control for the working of this equipment, cooling process was modeled by choosing one from different cooling technique. Constant low speed fan at one direction of air flow was used for cooling to predict the reducing of heating temperature through working of this equipment. Numerical Solution of finite difference time domain method （FDTD） has been utilized to simulate the temporal and spatial temperature profiles through two processes, which would minimize the solution errors.
文摘Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-developed software Position And Navigation Data Analysis(PANDA) and Beidou Experimental Tracking Stations (BETS),which are built by Wuhan University,the study of Beidou precise orbit determination,static precise point positioning (PPP),and high precision relative positioning,and differential positioning are carried out comprehensively.Results show that the radial precision of the Beidou satellite orbit determination is better than 10 centimeters.The RMS of static PPP can reach several centimeters to even millimeters for baseline relative positioning.The precision of kinematic pseudo-range differential positioning and RTK mode positioning are 2-4 m and 5-10 cm respectively,which are close to the level of GPS precise positioning.Research in this paper verifies that,with support of ground reference station network,Beidou satellite navigation system can provide precise positioning from several decimeters to meters in the wide area and several centimeters in the regional area.These promising results would be helpful for the implementation and applications of Beidou satellite navigation system.
基金supported by the National Natural Science Foundation of Chi-na(Grant Nos.41075002,40775004,41030960)R&D Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201006005-03)
文摘Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation sources and then extracting the lightning channel,it can accurately obtain the length of the channel.To validate the feasibility of the approach,a simulation experiment is designed,and it shows the length error is no more than 10%.The relationship between the NO production of per unit arc length and atmospheric pressure obtained in laboratory is applied to the NOX production of per unit flash length at different altitudes in this paper.The channel length and the NOX production of 11 negative cloud-to-ground flashes and 59 intracloud flashes in an isolated thunderstorm in the northeastern Qinghai-Tibet Plateau are calculated.The results show that the average channel lengths of per cloud-to-ground and intracloud flash are 28.9 and 22.3 km respectively;the average NOX productions of per cloud-to-ground and intracloud flash are 1.89×1025 and 0.42×1025 molecules,respectively.
