The Qaidam Basin in the NE Tibetan Plateau has contributed the largest amount of potash in China.However,how the potash was formed has long been a subject of debate.Here we carried out a deep drilling
Abstract： In the hot strip rolling control system, the temperature distribution and deformation resistance are the main parameters affecting prediction of rolling force. In order to improve the model prediction preci...Abstract： In the hot strip rolling control system, the temperature distribution and deformation resistance are the main parameters affecting prediction of rolling force. In order to improve the model prediction precision, an optimiza- tion algorithm based on objective function was put forward, in which the penalty function index was adopted. During the adaptation process, the temperature distribution and deformation resistance were taken as the optimized parame ters, and the Nelder-Mead simplex algorithm was used to search the optimal solution of the objective function. Fur thermore, the temperature adaptation and force adaptation were solved simultaneously. Application results show that the method can improve the accuracy of the rolling force model obviously, and it can meet the demand of the indus trial production and has a good application prospect.展开更多
（TiCp＋ TiBw）/Ti-6Al-4V titanium matrix composites（PTMCs） have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforc...（TiCp＋ TiBw）/Ti-6Al-4V titanium matrix composites（PTMCs） have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.展开更多
A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for th...A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge. Also, the deformation of a workpiece was estimated in the second step using the ANSYS. The deformation was analyzed for a 150 mm-long workpiece at three different measuring points, such as 10, 70 and 130 mm from a reference point, and the amounts of the deformation were compared through experiments. /n the results of the comparison and analysis, the values obtained from these comparison and analysis represent similar tendencies. Also, it is verified that their geometric errors increase with the increase in temperature. In addition, regarding the factors that affect the deformation of a workpiecc, it can be seen that the geometric error in the lathe is about 15%, the error caused by the cutting force is about 10%, and the deformation caused by the heat is about 75%.展开更多
The combustion chamber temperature of newgeneration aircraft engines can reach an ultrahigh temperature of 1800℃,making temperature monitoring of key components crucial.Thin-film thermocouples(TFTCs)are highly sensit...The combustion chamber temperature of newgeneration aircraft engines can reach an ultrahigh temperature of 1800℃,making temperature monitoring of key components crucial.Thin-film thermocouples(TFTCs)are highly sensitive and have rapid response times;however,their upper-temperature limit remains below 1800℃.This study proposes an ultrahightemperature film thermocouple,which is enhanced by yttriastabilized zirconia(YSZ)for positive films,indium oxide(In_(2)O_(3))for negative films,and aluminum oxide(Al_(2)O_(3))for protective films.The thermocouple is designed on the basis of temperature measurement principles,first principles,and simulations,and it is manufactured via screen printing.The results indicate that the maximum working temperature is 1850℃.In experiments with different doping ratios at 1800℃,the thermocouple achieves a maximum temperature electromotive force(TEMF)of 258.5 mV and a maximum Seebeck coefficient of 180.9μV/℃,with an In_(2)O_(3):YSZ92(ZrO_(2)(92 wt%):Y_(2)O_(3)(8 wt%))ratio of 9:1 in wt%.Through the lumped heat capacity method,the response time was measured at 2.8 ms,which demonstrated good dynamic response characteristics.A film thermocouple was successfully utilized to measure a gas temperature of 1090℃ at the outlet of an air turbine rocket(ATR)engine,confirming its high-temperature operational capability.To improve the repeatability of the TFTCs without affecting their thermoelectric outputs,a convolutional neural network-long short-term memory network(CNN-LSTM)-attention neural network is implemented to mitigate the repeatability errors,achieving a high repeatability of 99.53%.Additionally,the compensated temperature data are compared with those obtained from a standard B-type thermocouple,showing a full-scale error of±0.73%FS.This study provides a feasible solution for ultrahigh temperature measurements.展开更多
The results from some general circulation models show distinct radiative forcing （RF） by dust aerosol, which potentially has an effect on climate change. The direct RF and regional climatic effects of dust aerosol o...The results from some general circulation models show distinct radiative forcing （RF） by dust aerosol, which potentially has an effect on climate change. The direct RF and regional climatic effects of dust aerosol over the East Asian region are investigated in this study using NCAR＇s Community Atmospheric Model version 3.1. The negative RF at the top of the atmosphere （TOA） and the surface （SRF） has been revealed except for some high-albedo regions, which leads to a decrease in the surface air temperature and brings an increase of atmospheric radiative heating under both clear- and all-sky conditions. The decrease in the surface air temperature can be found over a wide region that includes the Indian peninsula and northwest China. It accompanies an increase in eastern China and the Korean peninsula, and temperature changes are not limited to regions with a large dust optical depth. A belt of vapor increase is revealed from the Indian peninsula extending east to northern China, while vapor content evidently deceases in southwest China. An increase in precipitation can also be found in the belt of increased vapor accompanying the reduction of precipitation across the regions to the south of 30~N. The pattern of rainfall change helps to offset the trend of increasing wetness in the south and increasing dryness in the north of China in recent years.展开更多
文摘The Qaidam Basin in the NE Tibetan Plateau has contributed the largest amount of potash in China.However,how the potash was formed has long been a subject of debate.Here we carried out a deep drilling
基金Sponsored by National Natural Science Foundation of China(51074051)The Fundamental Research Funds for the CentralUniversities of China(N110307001)
文摘Abstract： In the hot strip rolling control system, the temperature distribution and deformation resistance are the main parameters affecting prediction of rolling force. In order to improve the model prediction precision, an optimiza- tion algorithm based on objective function was put forward, in which the penalty function index was adopted. During the adaptation process, the temperature distribution and deformation resistance were taken as the optimized parame ters, and the Nelder-Mead simplex algorithm was used to search the optimal solution of the objective function. Fur thermore, the temperature adaptation and force adaptation were solved simultaneously. Application results show that the method can improve the accuracy of the rolling force model obviously, and it can meet the demand of the indus trial production and has a good application prospect.
基金co-supported by the National Natural Science Foundation of China (Nos. 51235004, 51375235)the Fundamental Research Funds for the Central Universities (No. NE2014103) of ChinaPriority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) of China
文摘（TiCp＋ TiBw）/Ti-6Al-4V titanium matrix composites（PTMCs） have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.
基金Project(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge. Also, the deformation of a workpiece was estimated in the second step using the ANSYS. The deformation was analyzed for a 150 mm-long workpiece at three different measuring points, such as 10, 70 and 130 mm from a reference point, and the amounts of the deformation were compared through experiments. /n the results of the comparison and analysis, the values obtained from these comparison and analysis represent similar tendencies. Also, it is verified that their geometric errors increase with the increase in temperature. In addition, regarding the factors that affect the deformation of a workpiecc, it can be seen that the geometric error in the lathe is about 15%, the error caused by the cutting force is about 10%, and the deformation caused by the heat is about 75%.
基金supported in part by the National Key R&D Program(No.2023YFB3209600)the National Natural Science Foundation of China(No.52475570).
文摘The combustion chamber temperature of newgeneration aircraft engines can reach an ultrahigh temperature of 1800℃,making temperature monitoring of key components crucial.Thin-film thermocouples(TFTCs)are highly sensitive and have rapid response times;however,their upper-temperature limit remains below 1800℃.This study proposes an ultrahightemperature film thermocouple,which is enhanced by yttriastabilized zirconia(YSZ)for positive films,indium oxide(In_(2)O_(3))for negative films,and aluminum oxide(Al_(2)O_(3))for protective films.The thermocouple is designed on the basis of temperature measurement principles,first principles,and simulations,and it is manufactured via screen printing.The results indicate that the maximum working temperature is 1850℃.In experiments with different doping ratios at 1800℃,the thermocouple achieves a maximum temperature electromotive force(TEMF)of 258.5 mV and a maximum Seebeck coefficient of 180.9μV/℃,with an In_(2)O_(3):YSZ92(ZrO_(2)(92 wt%):Y_(2)O_(3)(8 wt%))ratio of 9:1 in wt%.Through the lumped heat capacity method,the response time was measured at 2.8 ms,which demonstrated good dynamic response characteristics.A film thermocouple was successfully utilized to measure a gas temperature of 1090℃ at the outlet of an air turbine rocket(ATR)engine,confirming its high-temperature operational capability.To improve the repeatability of the TFTCs without affecting their thermoelectric outputs,a convolutional neural network-long short-term memory network(CNN-LSTM)-attention neural network is implemented to mitigate the repeatability errors,achieving a high repeatability of 99.53%.Additionally,the compensated temperature data are compared with those obtained from a standard B-type thermocouple,showing a full-scale error of±0.73%FS.This study provides a feasible solution for ultrahigh temperature measurements.
基金sponsored by the National Key Program for Developing Basic Sciences of China(No.2006CB400506),KZCX2-YW-Q11-03the Hundred Talents Program(Aerosol Characteristics and its Climatic Impact)of the Chinese Academyof Sciences+2 种基金sponsored by the Chinese Natural Science Foundation(40975092)the Natural Science Foundation(2009CD021)the Foundation of Younger Scholars in Science and Technology(2009CI046)of Yunnan Province
文摘The results from some general circulation models show distinct radiative forcing （RF） by dust aerosol, which potentially has an effect on climate change. The direct RF and regional climatic effects of dust aerosol over the East Asian region are investigated in this study using NCAR＇s Community Atmospheric Model version 3.1. The negative RF at the top of the atmosphere （TOA） and the surface （SRF） has been revealed except for some high-albedo regions, which leads to a decrease in the surface air temperature and brings an increase of atmospheric radiative heating under both clear- and all-sky conditions. The decrease in the surface air temperature can be found over a wide region that includes the Indian peninsula and northwest China. It accompanies an increase in eastern China and the Korean peninsula, and temperature changes are not limited to regions with a large dust optical depth. A belt of vapor increase is revealed from the Indian peninsula extending east to northern China, while vapor content evidently deceases in southwest China. An increase in precipitation can also be found in the belt of increased vapor accompanying the reduction of precipitation across the regions to the south of 30~N. The pattern of rainfall change helps to offset the trend of increasing wetness in the south and increasing dryness in the north of China in recent years.
