Generating electricity from wave is predicted to be a new source of renewable energy conversion gaining more attention and is considered in various countries as promising renewable resource. Being surrounded by sea, M...Generating electricity from wave is predicted to be a new source of renewable energy conversion gaining more attention and is considered in various countries as promising renewable resource. Being surrounded by sea, Malaysia has the advantage of tapping energy from the nearest sea wave. However, Malaysia has low wave climate compared to other regions. On top of that, the technologies available for extracting this energy are still in infancy stage. This study explored the potential of generating electricity from low height wave energy. The recorded average electricity can be generated from the lab scale device which is 0.224 V, 0.175 A and 0.039 W. The data collected from Mukah Beach show that the maximum voltage recorded is 1.021 V, maximum current of 0.86 A and highest power of 0.878 W. By comparing results from both locations, the difference is almost 10-fold which validates the wave maker built in laboratory with 1:10 ratio. The standard deviation of all the outputs is small which indicates that the output generation from low height wave would be consistent. Although the output is small, it could be paired together to make a larger system to generate higher output. This study concludes that the developed lab scale model is useful for harnessing electrical energy from sea wave. The future direction of research would be to optimize the current method to maximize energy capture from sea wave. Another direction for future study is to make a system comprised of a large number of such devices to generate higher output.展开更多
为解决短波辐射源到达时间差(time difference of arrival,TDOA)定位(简称时差定位)方法受电离层影响导致的定位精度下降的问题,提出了一种利用参考源修正的短波辐射源目标时差定位方法。针对地球表面短波辐射源,基于电离层球面反射模...为解决短波辐射源到达时间差(time difference of arrival,TDOA)定位(简称时差定位)方法受电离层影响导致的定位精度下降的问题,提出了一种利用参考源修正的短波辐射源目标时差定位方法。针对地球表面短波辐射源,基于电离层球面反射模型的电离层反射虚高近似方法,建立了利用参考修正的短波目标时差定位模型。考虑参考源与目标共用电离层反射区域对电离层虚高的影响,将各电离层反射点的距离相关性引入电离层虚高的协方差矩阵中,实现了目标定位精度的修正。通过推导和仿真所提模型的克拉美·罗下界,分析了参考源修正目标定位精度的可行性。进一步给出基于Armijo直线搜索Newton法的最大似然估计方法,通过仿真数据验证了所提算法的有效性,实现了良好的定位效果。展开更多
A barotropic model containing large-scale topography and zonal mean flow is established to discuss the effects of large-scale topography on the low-frequency waves. The results show that what affects low-frequency wav...A barotropic model containing large-scale topography and zonal mean flow is established to discuss the effects of large-scale topography on the low-frequency waves. The results show that what affects low-frequency waves mostly is maximal height of topography and topographic slope. The former makes frequency of topographic Rossby waves decrease, the latter makes Rossby waves instable. Moreover, when topographic slope is appropriate, it can also make Rossby waves turn into low-frequency waves.展开更多
The low-frequency variance of the surface wave in the area of the Antarctic Circumpolar Current （ACC） and its correlation with the antarctic circumpolar wave （ACW） are focused on. The analysis of the series of 44 ...The low-frequency variance of the surface wave in the area of the Antarctic Circumpolar Current （ACC） and its correlation with the antarctic circumpolar wave （ACW） are focused on. The analysis of the series of 44 a significant wave height （SWH） interannual anomalies reveals that the SWH anomalies have a strong periodicity of about 4-5 a and this signal propagates eastward obviously from 1985 to 1995, which needs about 8 a to complete a mimacircle around the earth. The method of empirical orthogonal function （EOF） is used to analyze the filtered monthly SWH anomalies to study the spatio-temporal distributions and the propagation characteristics of the low-frequency signals in the wave field. Both the dominant wavenumber- 2 pattern in space and the propagation feature in the south Pacific, the south Atlantic and the south Indian ocean show strong consistency with the ACW. So it is reasonable to conclude that the ACW signal also exists in the wave field. The ACW is important for the climate in the Southern Ocean, so it is worth to pay more attention to the large- scale effect of the surface wave, which may also be important for climate studies.展开更多
Combining with the exigent demand of the development of satellite gravimetry system in China, aiming at the determination of technical indexes of gravity satellite orbit parameters, on the basis of the numerical exper...Combining with the exigent demand of the development of satellite gravimetry system in China, aiming at the determination of technical indexes of gravity satellite orbit parameters, on the basis of the numerical experiments and results analysis, the design indexes of gravity satellite orbit height, inter-satellite range and the orbit inclination are analyzed and calculated, and the issues towards twin gravity satellites such as coherence requirement of the orbit semi-major axes, control requirement of the pitch angle and time interval requirement to keep twin satellites formation in mobility are diseussed. Results show that the satellite orbit height is 400 km to 500 km, the inter-satellite range is about 220 km, the satellite orbit inclination is between polar orbit and sun-synchronous orbit, the semi-major axes difference of twin satellites orbit is within ± 70. 146 m, the pitch angle of twin satellites is about 0.9 degree, and the time interval to keep twin satellites formation in mobility is 7 days to 15 days.展开更多
文摘Generating electricity from wave is predicted to be a new source of renewable energy conversion gaining more attention and is considered in various countries as promising renewable resource. Being surrounded by sea, Malaysia has the advantage of tapping energy from the nearest sea wave. However, Malaysia has low wave climate compared to other regions. On top of that, the technologies available for extracting this energy are still in infancy stage. This study explored the potential of generating electricity from low height wave energy. The recorded average electricity can be generated from the lab scale device which is 0.224 V, 0.175 A and 0.039 W. The data collected from Mukah Beach show that the maximum voltage recorded is 1.021 V, maximum current of 0.86 A and highest power of 0.878 W. By comparing results from both locations, the difference is almost 10-fold which validates the wave maker built in laboratory with 1:10 ratio. The standard deviation of all the outputs is small which indicates that the output generation from low height wave would be consistent. Although the output is small, it could be paired together to make a larger system to generate higher output. This study concludes that the developed lab scale model is useful for harnessing electrical energy from sea wave. The future direction of research would be to optimize the current method to maximize energy capture from sea wave. Another direction for future study is to make a system comprised of a large number of such devices to generate higher output.
文摘为解决短波辐射源到达时间差(time difference of arrival,TDOA)定位(简称时差定位)方法受电离层影响导致的定位精度下降的问题,提出了一种利用参考源修正的短波辐射源目标时差定位方法。针对地球表面短波辐射源,基于电离层球面反射模型的电离层反射虚高近似方法,建立了利用参考修正的短波目标时差定位模型。考虑参考源与目标共用电离层反射区域对电离层虚高的影响,将各电离层反射点的距离相关性引入电离层虚高的协方差矩阵中,实现了目标定位精度的修正。通过推导和仿真所提模型的克拉美·罗下界,分析了参考源修正目标定位精度的可行性。进一步给出基于Armijo直线搜索Newton法的最大似然估计方法,通过仿真数据验证了所提算法的有效性,实现了良好的定位效果。
文摘A barotropic model containing large-scale topography and zonal mean flow is established to discuss the effects of large-scale topography on the low-frequency waves. The results show that what affects low-frequency waves mostly is maximal height of topography and topographic slope. The former makes frequency of topographic Rossby waves decrease, the latter makes Rossby waves instable. Moreover, when topographic slope is appropriate, it can also make Rossby waves turn into low-frequency waves.
基金The National Natural Science Foundation of China under contract Nos 40976005 and 40930844
文摘The low-frequency variance of the surface wave in the area of the Antarctic Circumpolar Current （ACC） and its correlation with the antarctic circumpolar wave （ACW） are focused on. The analysis of the series of 44 a significant wave height （SWH） interannual anomalies reveals that the SWH anomalies have a strong periodicity of about 4-5 a and this signal propagates eastward obviously from 1985 to 1995, which needs about 8 a to complete a mimacircle around the earth. The method of empirical orthogonal function （EOF） is used to analyze the filtered monthly SWH anomalies to study the spatio-temporal distributions and the propagation characteristics of the low-frequency signals in the wave field. Both the dominant wavenumber- 2 pattern in space and the propagation feature in the south Pacific, the south Atlantic and the south Indian ocean show strong consistency with the ACW. So it is reasonable to conclude that the ACW signal also exists in the wave field. The ACW is important for the climate in the Southern Ocean, so it is worth to pay more attention to the large- scale effect of the surface wave, which may also be important for climate studies.
基金supported by the National Natural Science Foundation of China(41174026,41104047,41174017)the Key laboratory Foundation of Geo-space Environment and Geodesy of Ministry of Education(11-01-03)
文摘Combining with the exigent demand of the development of satellite gravimetry system in China, aiming at the determination of technical indexes of gravity satellite orbit parameters, on the basis of the numerical experiments and results analysis, the design indexes of gravity satellite orbit height, inter-satellite range and the orbit inclination are analyzed and calculated, and the issues towards twin gravity satellites such as coherence requirement of the orbit semi-major axes, control requirement of the pitch angle and time interval requirement to keep twin satellites formation in mobility are diseussed. Results show that the satellite orbit height is 400 km to 500 km, the inter-satellite range is about 220 km, the satellite orbit inclination is between polar orbit and sun-synchronous orbit, the semi-major axes difference of twin satellites orbit is within ± 70. 146 m, the pitch angle of twin satellites is about 0.9 degree, and the time interval to keep twin satellites formation in mobility is 7 days to 15 days.
基金the National Science & Technology Support Program inthe 12th Five-Year Plan of China (No.2011BAD20B09-10)The Fundamental Research Funds for the Central Universities (No.2012QJ118)
