An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measur...An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measuring Mission(TRMM) sea surface temperature(SST) data,a relatively high resolution data for space.This phenomenon only shows up in boreal summer(June to September),and becomes obvious when WPWP SST is higher than 29℃.As observed,East Asian summer monsoon(EASM) impinges on Philippine Islands in July,which has an important impact on the formation and maintenance of the "sandwich structure".Winds affect the distribution of SST in two ways:one by increasing the local latent heat flux and the other by transporting cold water towards the southeast of Philippine Islands.展开更多
Both 1981 and 2013 were weak La Nifia years with a similar sea surface temperature （SST） anomaly in the tropical Pacific, yet the westem Pacific subtropical high （WPSH） during August exhibited an opposite anomaly ...Both 1981 and 2013 were weak La Nifia years with a similar sea surface temperature （SST） anomaly in the tropical Pacific, yet the westem Pacific subtropical high （WPSH） during August exhibited an opposite anomaly in the two years. A comparison indicates that, in the absence of a strong SST anomaly in the tropics, the cold advection from Eurasian high latitudes and the convection of the western Pacific warm pool play important roles in influencing the strength and position of the WPSH in August. In August 1981, the spatial pattern of 500 hPa geopotential height was characterized by a meridional circulation with a strong ridge in the Ural Mountains and a deep trough in Siberia, which provided favorable conditions for cold air invading into the lower latitudes. Accordingly, the geopotential height to the north of the WPSH was reduced by the cold advection anomaly from high latitudes, resulting in an eastward retreat of the WPSH. Moreover, an anomalous cyclonic circulation in the subtropical western Pacific, excited by enhanced warm pool convection, also contributed to the eastward retreat of the WPSH. By contrast, the influence from high latitudes was relatively weak in August 2013 due to a zonal circulation pattern over Eurasia, and the anomalous anticyclonic circulation induced by suppressed warm pool convection also facilitated the westward extension of the WPSH. Therefore, the combined effects of the high latitude and tropical circulations may contribute a persistent anomaly of the WPSH in late summer, despite the tropical SST anomaly being weak.展开更多
Two measuring methods, high-speed camera and optical monitoring system, were used to study processes of laser welding. Molten pool, cooling time and temperature field were analyzed based on real measured images and op...Two measuring methods, high-speed camera and optical monitoring system, were used to study processes of laser welding. Molten pool, cooling time and temperature field were analyzed based on real measured images and optical signal data. The results show that the width of molten pool is almost equal to the width of weld, and length is about 7. 8 mm. The solidification time is about 0. 5 s and the temperature gradient is great, so HAZ is very small. The method and results will be of benefit to build the relationship between welding parameters and microstructure.展开更多
The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPW...The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPWP). The WPWP is chosen as the region (110–160°E, 10–20°N), where the Outgoing Longwave Radiation (OLR) shows a great year-to-year variance. A composite study was carried out to examine the differences in atmospheric circulation and SSTs between weak and strong convection over WPWP. First, NCEP/NCAR re-analysis data and satellite-observed OLR data are used to examine the differences. ERA data, in which the OLR data are calculated, are then used for re-examination. The composite results show that the differences are remarkably similar in these two sets of data. The difference in circulations between weak and strong convection over WPWP is significantly associated with westward extension of the North Pacific subtropical anticyclone and stronger westerlies at the northwestern edge of the subtropical anticyclone. It also corresponds with the significant easterly anomaly and the descent anomaly in situ, i.e., over the WPWP. The most prominent characteristics of the difference of SSTs between weak and strong convection over the WPWP are the significant positive SST anomalies in the Indian Ocean, the Bay of Bengal and the South China Sea. In WPWP, however, there are only weak negative SST anomalies. Thus, the anomaly of OLR over WPWP is weakly associated with the SST anomalies in situ, while closely associated with the SST anomalies west of WPWP. Key words Convection over the western Pacific warm pool - Northwest Pacific subtropical high - Sea surface temperatures This study was supported by the “ National Key Programme for Developing Basic Sciences” G1998040900 Part 1.展开更多
In contrast with Au/Ni/Al0.25Ga0.75N/GaN Schottky contacts, this paper systematically investigates the effect of thermal annealing of Au/Pt/Alo.25Ga0.75N/GaN structures on electrical properties of the two-dimensional ...In contrast with Au/Ni/Al0.25Ga0.75N/GaN Schottky contacts, this paper systematically investigates the effect of thermal annealing of Au/Pt/Alo.25Ga0.75N/GaN structures on electrical properties of the two-dimensional electron gas in Alo.25Ga0.75N/CaN heterostructures by means of temperature-dependent Hall and temperature-dependent current-voltage measurements. The two-dimensional electron gas density of the samples with Pt cap layer increases after annealing in N2 ambience at 600℃ while the annealing treatment has little effect on the two-dimensional electron gas mobility in comparison with the samples with Ni cap layer. The experimental results indicate that the Au/Pt/Al0.25Ga0.75N/GaN Schottky contacts reduce the reverse leakage current density at high annealing temperatures of 400-600 ℃. As a conclusion, the better thermal stability of the Au/Pt/Alo.25Gao.75N/GaN Schottky contacts than the Au/Ni/Al0.25Ga0.75N/GaN Schottky contacts at high temperatures can be attributed to the inertness of the interface between Pt and AlxGa1-xN.展开更多
In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in...In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in this way and the wavelets extracted with the seismic statistics techniques were used separately for inverting the seismic data of the southern part of Tahe oilfield, Tarim basin. The results showed that the resolution of the wavelet inversion with the higher-order statistics method was greatly improved, and the wavelet-inverted section could better distinguish the thin sandstone reservoirs of the upper and lower Carboniferous and their lateral distribution, providing a reliable basis of analysis for the study of thin sandstone reservoirs.展开更多
The electrode configuration determines the thermophysical field during the electroslag remelting(ESR) process and affects the final microstructure of the ingot. In this work, ingot with a diameter of 400 mm was prepar...The electrode configuration determines the thermophysical field during the electroslag remelting(ESR) process and affects the final microstructure of the ingot. In this work, ingot with a diameter of 400 mm was prepared with two electrode configuration modes of single power ESR process, namely one electrode(OE) and two series-connected electrodes(TSCE). Finite element simulation was employed to calculate the electromagnetic field, flow field and temperature field of the ESR system. The results show that the temperature of the slag pool and the metal pool of the TSCE process is lower and more uniform than that of the OE process.The calculated temperature distribution of the ingot could be indirectly verified from the shape of the metal pool by the experiment. The experimental results show that the depth of the metal pool in the OE ingot is about 160 mm, while the depth of the TSCE ingot is nearly 40 mm shallower than that of the OE ingot. Microstructural comparisons indicate that coarse eutectic carbides are formed in the center of the OE ingot, whereas more even eutectic carbides appear in the center of the TSCE ingot. In general, compared with the OE process, the TSCE process is preferred to remelt high speed steel ingots.展开更多
基金National Natural Science Foundation of China (40975038, 40830106)National Basic Research Program of China (973 Program:2012CB955604)+1 种基金Program from China Meteorological Administration (GYHY200906008)Project 111 (B07036)
文摘An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measuring Mission(TRMM) sea surface temperature(SST) data,a relatively high resolution data for space.This phenomenon only shows up in boreal summer(June to September),and becomes obvious when WPWP SST is higher than 29℃.As observed,East Asian summer monsoon(EASM) impinges on Philippine Islands in July,which has an important impact on the formation and maintenance of the "sandwich structure".Winds affect the distribution of SST in two ways:one by increasing the local latent heat flux and the other by transporting cold water towards the southeast of Philippine Islands.
基金supported by the National Science Foundation of China(Grant Nos.41475052 and 41405058)
文摘Both 1981 and 2013 were weak La Nifia years with a similar sea surface temperature （SST） anomaly in the tropical Pacific, yet the westem Pacific subtropical high （WPSH） during August exhibited an opposite anomaly in the two years. A comparison indicates that, in the absence of a strong SST anomaly in the tropics, the cold advection from Eurasian high latitudes and the convection of the western Pacific warm pool play important roles in influencing the strength and position of the WPSH in August. In August 1981, the spatial pattern of 500 hPa geopotential height was characterized by a meridional circulation with a strong ridge in the Ural Mountains and a deep trough in Siberia, which provided favorable conditions for cold air invading into the lower latitudes. Accordingly, the geopotential height to the north of the WPSH was reduced by the cold advection anomaly from high latitudes, resulting in an eastward retreat of the WPSH. Moreover, an anomalous cyclonic circulation in the subtropical western Pacific, excited by enhanced warm pool convection, also contributed to the eastward retreat of the WPSH. By contrast, the influence from high latitudes was relatively weak in August 2013 due to a zonal circulation pattern over Eurasia, and the anomalous anticyclonic circulation induced by suppressed warm pool convection also facilitated the westward extension of the WPSH. Therefore, the combined effects of the high latitude and tropical circulations may contribute a persistent anomaly of the WPSH in late summer, despite the tropical SST anomaly being weak.
文摘Two measuring methods, high-speed camera and optical monitoring system, were used to study processes of laser welding. Molten pool, cooling time and temperature field were analyzed based on real measured images and optical signal data. The results show that the width of molten pool is almost equal to the width of weld, and length is about 7. 8 mm. The solidification time is about 0. 5 s and the temperature gradient is great, so HAZ is very small. The method and results will be of benefit to build the relationship between welding parameters and microstructure.
基金This study was supported by the " National Key Programme for Developing Basic Sciences"G 1998040900 Part 1.
文摘The difference is examined in atmospheric circulation and Sea Surface Temperatures (SSTs) in the trop-ics and subtropics between weak and strong convection over the tropical western Pacific warm pool (signified as WPWP). The WPWP is chosen as the region (110–160°E, 10–20°N), where the Outgoing Longwave Radiation (OLR) shows a great year-to-year variance. A composite study was carried out to examine the differences in atmospheric circulation and SSTs between weak and strong convection over WPWP. First, NCEP/NCAR re-analysis data and satellite-observed OLR data are used to examine the differences. ERA data, in which the OLR data are calculated, are then used for re-examination. The composite results show that the differences are remarkably similar in these two sets of data. The difference in circulations between weak and strong convection over WPWP is significantly associated with westward extension of the North Pacific subtropical anticyclone and stronger westerlies at the northwestern edge of the subtropical anticyclone. It also corresponds with the significant easterly anomaly and the descent anomaly in situ, i.e., over the WPWP. The most prominent characteristics of the difference of SSTs between weak and strong convection over the WPWP are the significant positive SST anomalies in the Indian Ocean, the Bay of Bengal and the South China Sea. In WPWP, however, there are only weak negative SST anomalies. Thus, the anomaly of OLR over WPWP is weakly associated with the SST anomalies in situ, while closely associated with the SST anomalies west of WPWP. Key words Convection over the western Pacific warm pool - Northwest Pacific subtropical high - Sea surface temperatures This study was supported by the “ National Key Programme for Developing Basic Sciences” G1998040900 Part 1.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60906041,10774001,60736033,and 60890193)the National Basic Research Program of China (Grant Nos. 2006CB604908 and 2006CB921607)
文摘In contrast with Au/Ni/Al0.25Ga0.75N/GaN Schottky contacts, this paper systematically investigates the effect of thermal annealing of Au/Pt/Alo.25Ga0.75N/GaN structures on electrical properties of the two-dimensional electron gas in Alo.25Ga0.75N/CaN heterostructures by means of temperature-dependent Hall and temperature-dependent current-voltage measurements. The two-dimensional electron gas density of the samples with Pt cap layer increases after annealing in N2 ambience at 600℃ while the annealing treatment has little effect on the two-dimensional electron gas mobility in comparison with the samples with Ni cap layer. The experimental results indicate that the Au/Pt/Al0.25Ga0.75N/GaN Schottky contacts reduce the reverse leakage current density at high annealing temperatures of 400-600 ℃. As a conclusion, the better thermal stability of the Au/Pt/Alo.25Gao.75N/GaN Schottky contacts than the Au/Ni/Al0.25Ga0.75N/GaN Schottky contacts at high temperatures can be attributed to the inertness of the interface between Pt and AlxGa1-xN.
文摘In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in this way and the wavelets extracted with the seismic statistics techniques were used separately for inverting the seismic data of the southern part of Tahe oilfield, Tarim basin. The results showed that the resolution of the wavelet inversion with the higher-order statistics method was greatly improved, and the wavelet-inverted section could better distinguish the thin sandstone reservoirs of the upper and lower Carboniferous and their lateral distribution, providing a reliable basis of analysis for the study of thin sandstone reservoirs.
基金financially surpported by the Foundation of Hebei Provincial Department of Education,China(Grant No.QN2018034 and QN2017051)
文摘The electrode configuration determines the thermophysical field during the electroslag remelting(ESR) process and affects the final microstructure of the ingot. In this work, ingot with a diameter of 400 mm was prepared with two electrode configuration modes of single power ESR process, namely one electrode(OE) and two series-connected electrodes(TSCE). Finite element simulation was employed to calculate the electromagnetic field, flow field and temperature field of the ESR system. The results show that the temperature of the slag pool and the metal pool of the TSCE process is lower and more uniform than that of the OE process.The calculated temperature distribution of the ingot could be indirectly verified from the shape of the metal pool by the experiment. The experimental results show that the depth of the metal pool in the OE ingot is about 160 mm, while the depth of the TSCE ingot is nearly 40 mm shallower than that of the OE ingot. Microstructural comparisons indicate that coarse eutectic carbides are formed in the center of the OE ingot, whereas more even eutectic carbides appear in the center of the TSCE ingot. In general, compared with the OE process, the TSCE process is preferred to remelt high speed steel ingots.
