Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-l...Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented.展开更多
Based on direct current measurements from two separated cruises in October 2008-January 2009 and July-August 2009, we obtained a valuable deep current observation of the Luzon Strait (LS). Rectified wavelet power spec...Based on direct current measurements from two separated cruises in October 2008-January 2009 and July-August 2009, we obtained a valuable deep current observation of the Luzon Strait (LS). Rectified wavelet power spectra analysis (RWPSA) and the geostrophic current calculation are used to study the deep current. We find that the deep current differs in different seasons. The current is strongest in autumn (October-November) and weaker in summer (July-August) and in winter (December-January). The cyclonic and anti-cyclonic meander with different subtidal current directions plays an important role in the seasonal difference of the deep current in the LS. The observed seasonal difference of the deep current in the LS is connected with the deep current observed at the western boundary of the northern Philippine Basin and is also linked with the overflow near the central Bashi Channel and Luzon Trough. The RWPSA of the long observation suggests the dominant periods of 8 d, 19 d in the deep current. The dynamical cause of the resulting velocity distribution at 1850 and 1760 m is the pressure field and bottom topography steering. The observed deep current agrees well with the geostrophic current calculation.展开更多
On the basis of the current measurements from the moored Long Ranger ADCP in the upper 450 m layer and the deep current measurements at 2000 and 2300 m from the moored current meters with the time series data of about...On the basis of the current measurements from the moored Long Ranger ADCP in the upper 450 m layer and the deep current measurements at 2000 and 2300 m from the moored current meters with the time series data of about 7 months at the mooring station in the northeastern South China Sea, the spectral analyses and calculation have been made. The major results are as follows: (i) From the progressive vector diagrams of the observed daily currents at the water levels from 50 m to 400 m, its temporal variation of velocity rotated counterclockwise in most of the observing time. This agrees basically with the result from the qualitative analysis of the sea surface height data, which was obtained from TOPEX/ERS-2 altimeter data by CCAR. The daily and monthly average velocities are both the largest in November, next in October and minimum in August. (ii) At the 2000 and 2300 m levels, the daily and monthly average velocities are both the largest in January, next in September and minimum in August. From the seasonal change of currents, the current velocity is the strongest in winter (January-March), next in autumn, and weak in summer. (iii) There exists the variation of tidal current with the change of depth. In the upper layer, the height of diurnal peak is higher than that of semidiurnal peak. However, the semidiurnal peak is higher than the diurnal peak at the levels from 200 m to 400 m. In the layers above 450 m the clockwise component is dominant in their fluctuations. In the layers below 1500 m the diurnal peak is again higher than the semidiurnal peak. (iv) There is the prominent periodic fluctuation of more than two months in the layer from 50 m to 2300 m. The period of this prominent peak is 75 d and its fluctuation is counterclockwise in the upper 450 m layers, and is 68 d and 69 d at the depths of 2000 and 2300 m, respectively, and the counterclockwise component is dominant in their fluctuations. (v) There are the variations of periods fluctuating with the change of depth in the upper 450 m layers. For example, when f>0, there are the prominent fluctuations of about 22 d and 15 d period at the 50 and 100 m levels. However, there are no such periods at the layer from 200 m to 400 m, where only the fluctuation of about 13 d period occurs. (vi) There are the fluctuations with periods of more than one month, 23 d and 15 d at the 2000 m and 2300 m levels. (vii) In the layer from 50 m to 2300 m there are the following prominent peaks: i) the fluctuation in the period range of about 4-8 d, which occurs in the weather process; ii) the fluctuation with inertial period, the fluctuation is clockwise; and iii) the fluctuations with short periods of about 8 h and 6 h. (viii) From the cross spectral estimates between two time series, it is shown that there are significant coherence peaks with the periods of more than two months(T = 68.3 d) and more than one month between the two time series of currents at 2000 m and 2300 m depths, and also those with periods of about half a month (15.5 d), 2 d and so on between two time series of currents at 100 m and 2300 m depths.展开更多
The acoustic Echo Intensity (EI) was recorded with 38k shipborne AcousticDoppler Current Profiler (AD-CP) in the Western Pacific in four cruises between Sept. 2001 and Oct.2002. The main Deep Scattering Layer (DSL) wa...The acoustic Echo Intensity (EI) was recorded with 38k shipborne AcousticDoppler Current Profiler (AD-CP) in the Western Pacific in four cruises between Sept. 2001 and Oct.2002. The main Deep Scattering Layer (DSL) was observed at 400m-600 m depth in the four cruises. Thelatitudinal variation of the main DSL, which has high level of back-scatter strength (BS) at highlatitude, is prominent during both nighttime and daytime. The influences of environmental conditionson the DSL are discussed. Since high-oxygen water in the north is a friendly environment of marineanimals which form the main DSL, more animals are expected to aggregate in the 400dbars-600dbarslayer in the north. Dissolved Oxygen (DO) is the principal factor that causes the main DSL to varywith latitude, and its spatial distributions result from formation and transport of North PacificIntermediate Water (NPIW).展开更多
In underground mines, high air temperatures in the summer months lead to an increase in inlet airflow temperatures. This leads to seasonal thermal pollution in the mines. This paper examines the dynamics and effects o...In underground mines, high air temperatures in the summer months lead to an increase in inlet airflow temperatures. This leads to seasonal thermal pollution in the mines. This paper examines the dynamics and effects of seasonal variation in surface air temperatures and surrounding rock temperatures in deep coal mines. It also examines temperature variations in the main ventilation circuit, working face, and surrounding rock. The study results revealed that airflow temperatures were significantly affected by seasonal air temperature variations. The greater the distance was between the inlet and the wellhead of the ventilation shaft, the less the effect was on temperature. Moreover, slight temperature variations (1.0-3.0 ℃) were observed between various points on the return route during the summer months. Airflow temperatures along the airflow inlet to the return route of the working face first decreased, but then increased. The temperature field of the surrounding rock increased gradually with increased distance between the mine roadway and inlet, with recorded rock temperatures as high as 40.53 ℃. The radius of the heat-adjusting layer was between 28 and 33 m.展开更多
文摘Luquire et al. ' s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented.
文摘Based on direct current measurements from two separated cruises in October 2008-January 2009 and July-August 2009, we obtained a valuable deep current observation of the Luzon Strait (LS). Rectified wavelet power spectra analysis (RWPSA) and the geostrophic current calculation are used to study the deep current. We find that the deep current differs in different seasons. The current is strongest in autumn (October-November) and weaker in summer (July-August) and in winter (December-January). The cyclonic and anti-cyclonic meander with different subtidal current directions plays an important role in the seasonal difference of the deep current in the LS. The observed seasonal difference of the deep current in the LS is connected with the deep current observed at the western boundary of the northern Philippine Basin and is also linked with the overflow near the central Bashi Channel and Luzon Trough. The RWPSA of the long observation suggests the dominant periods of 8 d, 19 d in the deep current. The dynamical cause of the resulting velocity distribution at 1850 and 1760 m is the pressure field and bottom topography steering. The observed deep current agrees well with the geostrophic current calculation.
基金This work was supported by the State Basic Research Program of China (Grand Nos. G1999043805 and G1999043810)
文摘On the basis of the current measurements from the moored Long Ranger ADCP in the upper 450 m layer and the deep current measurements at 2000 and 2300 m from the moored current meters with the time series data of about 7 months at the mooring station in the northeastern South China Sea, the spectral analyses and calculation have been made. The major results are as follows: (i) From the progressive vector diagrams of the observed daily currents at the water levels from 50 m to 400 m, its temporal variation of velocity rotated counterclockwise in most of the observing time. This agrees basically with the result from the qualitative analysis of the sea surface height data, which was obtained from TOPEX/ERS-2 altimeter data by CCAR. The daily and monthly average velocities are both the largest in November, next in October and minimum in August. (ii) At the 2000 and 2300 m levels, the daily and monthly average velocities are both the largest in January, next in September and minimum in August. From the seasonal change of currents, the current velocity is the strongest in winter (January-March), next in autumn, and weak in summer. (iii) There exists the variation of tidal current with the change of depth. In the upper layer, the height of diurnal peak is higher than that of semidiurnal peak. However, the semidiurnal peak is higher than the diurnal peak at the levels from 200 m to 400 m. In the layers above 450 m the clockwise component is dominant in their fluctuations. In the layers below 1500 m the diurnal peak is again higher than the semidiurnal peak. (iv) There is the prominent periodic fluctuation of more than two months in the layer from 50 m to 2300 m. The period of this prominent peak is 75 d and its fluctuation is counterclockwise in the upper 450 m layers, and is 68 d and 69 d at the depths of 2000 and 2300 m, respectively, and the counterclockwise component is dominant in their fluctuations. (v) There are the variations of periods fluctuating with the change of depth in the upper 450 m layers. For example, when f>0, there are the prominent fluctuations of about 22 d and 15 d period at the 50 and 100 m levels. However, there are no such periods at the layer from 200 m to 400 m, where only the fluctuation of about 13 d period occurs. (vi) There are the fluctuations with periods of more than one month, 23 d and 15 d at the 2000 m and 2300 m levels. (vii) In the layer from 50 m to 2300 m there are the following prominent peaks: i) the fluctuation in the period range of about 4-8 d, which occurs in the weather process; ii) the fluctuation with inertial period, the fluctuation is clockwise; and iii) the fluctuations with short periods of about 8 h and 6 h. (viii) From the cross spectral estimates between two time series, it is shown that there are significant coherence peaks with the periods of more than two months(T = 68.3 d) and more than one month between the two time series of currents at 2000 m and 2300 m depths, and also those with periods of about half a month (15.5 d), 2 d and so on between two time series of currents at 100 m and 2300 m depths.
文摘The acoustic Echo Intensity (EI) was recorded with 38k shipborne AcousticDoppler Current Profiler (AD-CP) in the Western Pacific in four cruises between Sept. 2001 and Oct.2002. The main Deep Scattering Layer (DSL) was observed at 400m-600 m depth in the four cruises. Thelatitudinal variation of the main DSL, which has high level of back-scatter strength (BS) at highlatitude, is prominent during both nighttime and daytime. The influences of environmental conditionson the DSL are discussed. Since high-oxygen water in the north is a friendly environment of marineanimals which form the main DSL, more animals are expected to aggregate in the 400dbars-600dbarslayer in the north. Dissolved Oxygen (DO) is the principal factor that causes the main DSL to varywith latitude, and its spatial distributions result from formation and transport of North PacificIntermediate Water (NPIW).
基金This work was supported by the National Natural Science Foundation of China (Nos. 5157-4139 and 5180-4247)De Montfort University through its distinguished Vice-Chancellor 2020 ProgrammeUK Science and Technology Facilities Council (STFC) through Batteries Early Career Researcher Award.
文摘In underground mines, high air temperatures in the summer months lead to an increase in inlet airflow temperatures. This leads to seasonal thermal pollution in the mines. This paper examines the dynamics and effects of seasonal variation in surface air temperatures and surrounding rock temperatures in deep coal mines. It also examines temperature variations in the main ventilation circuit, working face, and surrounding rock. The study results revealed that airflow temperatures were significantly affected by seasonal air temperature variations. The greater the distance was between the inlet and the wellhead of the ventilation shaft, the less the effect was on temperature. Moreover, slight temperature variations (1.0-3.0 ℃) were observed between various points on the return route during the summer months. Airflow temperatures along the airflow inlet to the return route of the working face first decreased, but then increased. The temperature field of the surrounding rock increased gradually with increased distance between the mine roadway and inlet, with recorded rock temperatures as high as 40.53 ℃. The radius of the heat-adjusting layer was between 28 and 33 m.
