According to the latest data released in Journal Citation Reports(JCR) by Web of Science on June 20 th, 2019, there are 31 academic journals in the discipline of engineering aerospace worldwide covered by SCI. Among S...According to the latest data released in Journal Citation Reports(JCR) by Web of Science on June 20 th, 2019, there are 31 academic journals in the discipline of engineering aerospace worldwide covered by SCI. Among SCI-covered aerospace journals, Chinese Journal of Aeronautics(CJA), as the only China-sponsored journal, keeps its excellent performance.展开更多
The journalist learned from the "National Gas Security Working Conference" held recently that the coal seam gas power generation has been rapidly developed in recent years.As of July 2009,within the SGCC'...The journalist learned from the "National Gas Security Working Conference" held recently that the coal seam gas power generation has been rapidly developed in recent years.As of July 2009,within the SGCC's business area,the power generation展开更多
As of December 27,2020,the annual production of oil and gas equivalent in Changqing Oilfield has reached 60.08 million tons,exceeding 60 million tons,including the production of crude oil of 24.518 million tons and th...As of December 27,2020,the annual production of oil and gas equivalent in Changqing Oilfield has reached 60.08 million tons,exceeding 60 million tons,including the production of crude oil of 24.518 million tons and the production of natural gas of 44.531 billion cubic meters.It marked that Changqing Oilfield became the first super-large oil and gas field in China to reach the 60-million-ton mark in annual oil and gas output,inaugurating a new era in the history of China’s oil industry.展开更多
Online travel agency Ctrip released its 2022 National Day holiday forecast on Sept.15,which shows that starting from the Mid-Autumn Festival(Sept.10),the National Day holiday tourist orders have been on a steady rise,...Online travel agency Ctrip released its 2022 National Day holiday forecast on Sept.15,which shows that starting from the Mid-Autumn Festival(Sept.10),the National Day holiday tourist orders have been on a steady rise,with the average daily order growth rate exceeding 30 percent.展开更多
Nonreciprocal isolators enable unidirectional light propagation without back-reflection.Typical terahertz isolators require magnetic fields to break the time-reversal symmetry.Herein,we propose a nonmagnetic isolator ...Nonreciprocal isolators enable unidirectional light propagation without back-reflection.Typical terahertz isolators require magnetic fields to break the time-reversal symmetry.Herein,we propose a nonmagnetic isolator in the terahertz range based on nonreciprocal graphene plasmons operated in a reflection configuration.The bias voltage generates a drift current in graphene,which breaks the time-reversal symmetry and induces nonreciprocal reflection.The isolator device exhibited a high isolation exceeding 20 d B with an insertion loss of less than 3 d B.Moreover,the bandwidth wit isolation exceeding 20 d B can be broadened five times to 1.7 THz by tuning the carrier density.The indexes,including the isolation,insertion loss and bandwidth of the isolator,show a strong dependence on the drift velocity and mobility of graphene,as well as the air-gap thickness.Our study shows great potential in the burgeoning terahertz technology,where nonmagnetic and electrically tunable isolators are still lacking.展开更多
This letter describes the implementation of a high-precision time and frequency transmission system using a two-way and wavelength division multiplexing scheme over 3,143.6 km of field fiber links,connecting 21 sites ...This letter describes the implementation of a high-precision time and frequency transmission system using a two-way and wavelength division multiplexing scheme over 3,143.6 km of field fiber links,connecting 21 sites between Xi’an and Beijing,China.This scheme incorporates a link noise clean-up system(LNCUS),wherein a controlled very-low-phase noise BVA oscillator acts as an internal frequency source at the relay site to effectively suppress the interference caused by the fiber link noise.Additionally,the high-stability pulse generation technology in the LNCPS provides sufficient short-term stability to significantly improve the stability of the fiber time transfer.The results indicate a time transfer stability in terms of time deviation(TDEV)of less than2.07 ps@1s,5.9 ps@100,000s,and combined uncertainty of less than 49.29 ps for the 3,143.6 km field fiber link.The results represent a significant breakthrough in achieving high-accuracy time transfer and continuous operation over ultralong-span field optical fibers exceeding 3,000 km for the first time.This enabled time transfer and synchronization services over the longest international optical fiber distance,thereby establishing a fundamental basis for constructing a nationwide high-precision time service through optical fiber networks.展开更多
1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic inform...1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic information sciences,remote sensing and cartography.Manuscripts come from different parts of the world.2 Format and style Contributions should be typed on A4 paper using Times New Roman typeface in Word format,normally not exceeding 20,000 words.3 Abstract and keywords The text should be preceded by an abstract of 200-300 words,which should be followed by 3-7keywords on a separate line.展开更多
Polarization control and modulation of optical signals play a crucial role in optical information transmission,with widespread applications in optical communication,sensing,and signal processing.Here,we propose an int...Polarization control and modulation of optical signals play a crucial role in optical information transmission,with widespread applications in optical communication,sensing,and signal processing.Here,we propose an intrinsically chiral nano-kirigami metasurface featuring out-of-plane twisting,which enables switchable spinselective light transmission.At the operating wavelength,it nearly completely blocks the transmission of one type of circularly polarized light while maintaining a transmission exceeding 70%for the other type.Crucially,by merely adjusting the rotation angles or deformation heights of the four arms of the nano-kirigami structures,the metasurface can switch from selective transmission of left-handed circularly polarized light to right-handed circularly polarized light,and vice versa,without the need for dramatic structural geometric chirality changes through mirror operations.Simultaneously,a remarkable circular dichroism of up to 0.74 is achieved,and its sign reverses with the transition of transmission.Electromagnetic multipolar analysis reveals that this switching of chiral response is governed by handedness-dependent excitations of toroidal dipole modes.Additionally,the spin-encoded near-field imaging results demonstrate the potential applications of this switchable spin-selective transmission based on nano-kirigami metasurfaces in digital imaging and chiroptical encryption.展开更多
1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic inform...1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic information sciences,remote sensing and cartography.Manuscripts come from different parts of the world.2 Format and style Contributions should be typed on A4 paper using Times New Roman typeface in Word format,normally not exceeding 20,000 words.展开更多
Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of e...Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of exceeded tolerance hole is necessary and meaningful from the perspective of suiting more and more wide-scrapped equipment in the industrial field.UltrasonicAssisted R-AFSR(UA-RAFSR)is proposed as a strategy to achieve the 2024 aluminum(Al)alloy repaired hole with high strength.Analyses of microstructure formation indicate that the addition of ultrasonic eliminated the kissing bond and“S”line,refined the grain size,enlarged the interfacial bonding area and enhanced the atomic diffusion.Thus,the mechanical properties of 2024 Al alloy repaired hole were heightened by ultrasonic,and the maximum compressive shear and tensile strengths respectively reached 214.5 MPa and 297.3 MPa,which were 98.6% and 94.0% of those of the standard mechanical hole.The research results confirm that the UA-RAFSR is a powerful technology for the nearly-equal-strength repair of exceeded tolerance hole.展开更多
Marine services-ranging from ocean tourism and maritime transport to public marine services-have become a powerful driver of China’s ocean economy.In 2024,the country’s gross ocean product(GOP)exceeded 10 trillion y...Marine services-ranging from ocean tourism and maritime transport to public marine services-have become a powerful driver of China’s ocean economy.In 2024,the country’s gross ocean product(GOP)exceeded 10 trillion yuan(US$1.4 trillion)for the first time,with marine services contributing 6.28 trillion yuan(US$880 billion),or 59.6 percent of the total.Among them,marine tourism and maritime transport accounted for the lion’s share.展开更多
介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,...介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,并与国外同类的钠热管固定点炉的技术指标进行比较.此外,分析了影响固定点炉等温性能的因素.
Abstract：
Two sodium heat-pipe fixed point furnaces (SHPF-1, SHPF-2) developed at the National Institute of Metrology (NIM) are described, and their vertical temperature uniformities are measured. When the temperatures of the these two furnaces are controlled about 2 ℃ and 3 ℃ respectively, below the freezing point of the aluminum, the largest temperature differences did not exceed 15 mK and 11 mK in a distance about 150mm along the reentrant well of the aluminum point cell, respectively. These temperature uniformities are compared with those of foreign similar sodium heat pipe furnaces. Additionally, factors influencing isothermal characteristics of fixed point furnaces are analyzed.展开更多
With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprise...With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprises to positive response to the call of national energy conservation and emission reduction, using plant waste heat green development is the only way to realize the transformation and upgrading of the steel industry. This paper will be mainly for the domestic steel enterprise 6kV system short circuit current exceeds the limit and take the restrictive measures for detailed analysis and discussion for the industry reference.展开更多
Dementia is a progressive cognitive impairment that affects the activities of daily living.Alzheimer’s disease (AD) is the most common form of the dementia worldwide accounting for 60-80%of all dementia cases.With an...Dementia is a progressive cognitive impairment that affects the activities of daily living.Alzheimer’s disease (AD) is the most common form of the dementia worldwide accounting for 60-80%of all dementia cases.With an estimated cost exceeding$290 billion in the USA,understanding and development of future therapeutic strategies is vital.In this perspective,we will be examining the current thinking of AD research and therapeutic strategies,while proposing a possible new direction for diagnosis,understanding,and treatment targets.展开更多
Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ（n） =EX1Xn＋1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level （x/√2 l...Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ（n） =EX1Xn＋1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level （x/√2 log n＋√2 log n-log（4π log n）/2√log n） √1-τ（n） ＋ X^-n by X1,X2,…, Xn. Under some mild conditions, Nn and Sn are asymptotically independent, and Nn converges weakly to a Poisson process on （0,1].展开更多
The current acid deposition critical loads in Guangdong, China were calculated using the PROFILE model with a 3 km × 3 km resolution. Calculations were carded out for critical loads of potential acidity, actual a...The current acid deposition critical loads in Guangdong, China were calculated using the PROFILE model with a 3 km × 3 km resolution. Calculations were carded out for critical loads of potential acidity, actual acidity, sulfur and nitrogen, with values in extents of 0-3.5, 0-14.0, 0-26.0 and 0-3.5 kmol/（hrnE.year）, respectively. These values were comparable to previously reported results and reflected the influences of vegetation and soil characteristics on the soil acid buffering capacity. Simulations of SO2 emission and sulfur deposition in this study showed that sulfur deposition core areas mirrored SO2 emission centers. The prediction of sulfur deposition after 20% and 40% reduction of SO2 emission suggested that the reduction of area sources contributed greatly to the decrease of sulfur deposition. Thus, abatement of area source emissions could be the primary way to mitigate sulfur deposition in Guangdong to meet both the provincial and national regulations of air pollution control.展开更多
文摘According to the latest data released in Journal Citation Reports(JCR) by Web of Science on June 20 th, 2019, there are 31 academic journals in the discipline of engineering aerospace worldwide covered by SCI. Among SCI-covered aerospace journals, Chinese Journal of Aeronautics(CJA), as the only China-sponsored journal, keeps its excellent performance.
文摘The journalist learned from the "National Gas Security Working Conference" held recently that the coal seam gas power generation has been rapidly developed in recent years.As of July 2009,within the SGCC's business area,the power generation
文摘As of December 27,2020,the annual production of oil and gas equivalent in Changqing Oilfield has reached 60.08 million tons,exceeding 60 million tons,including the production of crude oil of 24.518 million tons and the production of natural gas of 44.531 billion cubic meters.It marked that Changqing Oilfield became the first super-large oil and gas field in China to reach the 60-million-ton mark in annual oil and gas output,inaugurating a new era in the history of China’s oil industry.
文摘Online travel agency Ctrip released its 2022 National Day holiday forecast on Sept.15,which shows that starting from the Mid-Autumn Festival(Sept.10),the National Day holiday tourist orders have been on a steady rise,with the average daily order growth rate exceeding 30 percent.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11934011 and 12274365)National Key R&D Program of China(Grant Nos.2022YFA1402400 and 2022YFA1400043)+1 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LR24A040001)Open project of Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education)of Shanghai Jiao Tong University。
文摘Nonreciprocal isolators enable unidirectional light propagation without back-reflection.Typical terahertz isolators require magnetic fields to break the time-reversal symmetry.Herein,we propose a nonmagnetic isolator in the terahertz range based on nonreciprocal graphene plasmons operated in a reflection configuration.The bias voltage generates a drift current in graphene,which breaks the time-reversal symmetry and induces nonreciprocal reflection.The isolator device exhibited a high isolation exceeding 20 d B with an insertion loss of less than 3 d B.Moreover,the bandwidth wit isolation exceeding 20 d B can be broadened five times to 1.7 THz by tuning the carrier density.The indexes,including the isolation,insertion loss and bandwidth of the isolator,show a strong dependence on the drift velocity and mobility of graphene,as well as the air-gap thickness.Our study shows great potential in the burgeoning terahertz technology,where nonmagnetic and electrically tunable isolators are still lacking.
文摘This letter describes the implementation of a high-precision time and frequency transmission system using a two-way and wavelength division multiplexing scheme over 3,143.6 km of field fiber links,connecting 21 sites between Xi’an and Beijing,China.This scheme incorporates a link noise clean-up system(LNCUS),wherein a controlled very-low-phase noise BVA oscillator acts as an internal frequency source at the relay site to effectively suppress the interference caused by the fiber link noise.Additionally,the high-stability pulse generation technology in the LNCPS provides sufficient short-term stability to significantly improve the stability of the fiber time transfer.The results indicate a time transfer stability in terms of time deviation(TDEV)of less than2.07 ps@1s,5.9 ps@100,000s,and combined uncertainty of less than 49.29 ps for the 3,143.6 km field fiber link.The results represent a significant breakthrough in achieving high-accuracy time transfer and continuous operation over ultralong-span field optical fibers exceeding 3,000 km for the first time.This enabled time transfer and synchronization services over the longest international optical fiber distance,thereby establishing a fundamental basis for constructing a nationwide high-precision time service through optical fiber networks.
文摘1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic information sciences,remote sensing and cartography.Manuscripts come from different parts of the world.2 Format and style Contributions should be typed on A4 paper using Times New Roman typeface in Word format,normally not exceeding 20,000 words.3 Abstract and keywords The text should be preceded by an abstract of 200-300 words,which should be followed by 3-7keywords on a separate line.
基金supported by the National Natural Science Foundation of China(Grant Nos.62205282 and 12074331)the Hebei Natural Science Foundation(Grant No.A2022203035)the Science and Technology Project of Hebei Education Department(Grant No.BJK2023009)。
文摘Polarization control and modulation of optical signals play a crucial role in optical information transmission,with widespread applications in optical communication,sensing,and signal processing.Here,we propose an intrinsically chiral nano-kirigami metasurface featuring out-of-plane twisting,which enables switchable spinselective light transmission.At the operating wavelength,it nearly completely blocks the transmission of one type of circularly polarized light while maintaining a transmission exceeding 70%for the other type.Crucially,by merely adjusting the rotation angles or deformation heights of the four arms of the nano-kirigami structures,the metasurface can switch from selective transmission of left-handed circularly polarized light to right-handed circularly polarized light,and vice versa,without the need for dramatic structural geometric chirality changes through mirror operations.Simultaneously,a remarkable circular dichroism of up to 0.74 is achieved,and its sign reverses with the transition of transmission.Electromagnetic multipolar analysis reveals that this switching of chiral response is governed by handedness-dependent excitations of toroidal dipole modes.Additionally,the spin-encoded near-field imaging results demonstrate the potential applications of this switchable spin-selective transmission based on nano-kirigami metasurfaces in digital imaging and chiroptical encryption.
文摘1 General information Journal of Geographical Sciences is an international academic journal that publishes papers of the highest quality in physical geography,natural resources,environmental sciences,geographic information sciences,remote sensing and cartography.Manuscripts come from different parts of the world.2 Format and style Contributions should be typed on A4 paper using Times New Roman typeface in Word format,normally not exceeding 20,000 words.
基金supported by the National Natural Science Foundation of China(Nos.51874201 and 52074184)the Fundamental Research Funds for the Universities of Liaoning Province,China(No.LJ222410143035)。
文摘Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of exceeded tolerance hole is necessary and meaningful from the perspective of suiting more and more wide-scrapped equipment in the industrial field.UltrasonicAssisted R-AFSR(UA-RAFSR)is proposed as a strategy to achieve the 2024 aluminum(Al)alloy repaired hole with high strength.Analyses of microstructure formation indicate that the addition of ultrasonic eliminated the kissing bond and“S”line,refined the grain size,enlarged the interfacial bonding area and enhanced the atomic diffusion.Thus,the mechanical properties of 2024 Al alloy repaired hole were heightened by ultrasonic,and the maximum compressive shear and tensile strengths respectively reached 214.5 MPa and 297.3 MPa,which were 98.6% and 94.0% of those of the standard mechanical hole.The research results confirm that the UA-RAFSR is a powerful technology for the nearly-equal-strength repair of exceeded tolerance hole.
文摘Marine services-ranging from ocean tourism and maritime transport to public marine services-have become a powerful driver of China’s ocean economy.In 2024,the country’s gross ocean product(GOP)exceeded 10 trillion yuan(US$1.4 trillion)for the first time,with marine services contributing 6.28 trillion yuan(US$880 billion),or 59.6 percent of the total.Among them,marine tourism and maritime transport accounted for the lion’s share.
文摘介绍了中国计量科学研究院新研制的两台高精度钠热管固定点炉(SHPF-1、SHPF-2),并测量了其垂直温场.当这两台钠热管固定点炉的炉温分别控制在比铝凝固点低约2℃、3℃时,铝点容器温度计阱底部150 mm范围内温场均匀性分别为15 mK和11 mK,并与国外同类的钠热管固定点炉的技术指标进行比较.此外,分析了影响固定点炉等温性能的因素.
Abstract：
Two sodium heat-pipe fixed point furnaces (SHPF-1, SHPF-2) developed at the National Institute of Metrology (NIM) are described, and their vertical temperature uniformities are measured. When the temperatures of the these two furnaces are controlled about 2 ℃ and 3 ℃ respectively, below the freezing point of the aluminum, the largest temperature differences did not exceed 15 mK and 11 mK in a distance about 150mm along the reentrant well of the aluminum point cell, respectively. These temperature uniformities are compared with those of foreign similar sodium heat pipe furnaces. Additionally, factors influencing isothermal characteristics of fixed point furnaces are analyzed.
文摘With the rapid development of economy, strengthen the continuous construction of national infrastructure, etc., many industry demand for steel, steel enterprise capacity expands, at the same time, the steel enterprises to positive response to the call of national energy conservation and emission reduction, using plant waste heat green development is the only way to realize the transformation and upgrading of the steel industry. This paper will be mainly for the domestic steel enterprise 6kV system short circuit current exceeds the limit and take the restrictive measures for detailed analysis and discussion for the industry reference.
基金supported by the Division of Rehabilitation Sciences,College of Health Professions,University of Tennessee Health Science Center。
文摘Dementia is a progressive cognitive impairment that affects the activities of daily living.Alzheimer’s disease (AD) is the most common form of the dementia worldwide accounting for 60-80%of all dementia cases.With an estimated cost exceeding$290 billion in the USA,understanding and development of future therapeutic strategies is vital.In this perspective,we will be examining the current thinking of AD research and therapeutic strategies,while proposing a possible new direction for diagnosis,understanding,and treatment targets.
基金Supported by the Program for Excellent Talents in Chongqing Higher Education Institutions (120060-20600204)
文摘Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ（n） =EX1Xn＋1, Sn =∑i=1^nXi,and X^-n=Sn/n.And let Nn be the point process formed by the exceedances of random level （x/√2 log n＋√2 log n-log（4π log n）/2√log n） √1-τ（n） ＋ X^-n by X1,X2,…, Xn. Under some mild conditions, Nn and Sn are asymptotically independent, and Nn converges weakly to a Poisson process on （0,1].
基金supported by Guangdong Provincial Natural Science Foundation (No. 02-38100-4202003 and 06202438)New Century Excellent Talents Program of Ministry of Education of the People’s Republic of China(No. NCET-04-0790)
文摘The current acid deposition critical loads in Guangdong, China were calculated using the PROFILE model with a 3 km × 3 km resolution. Calculations were carded out for critical loads of potential acidity, actual acidity, sulfur and nitrogen, with values in extents of 0-3.5, 0-14.0, 0-26.0 and 0-3.5 kmol/（hrnE.year）, respectively. These values were comparable to previously reported results and reflected the influences of vegetation and soil characteristics on the soil acid buffering capacity. Simulations of SO2 emission and sulfur deposition in this study showed that sulfur deposition core areas mirrored SO2 emission centers. The prediction of sulfur deposition after 20% and 40% reduction of SO2 emission suggested that the reduction of area sources contributed greatly to the decrease of sulfur deposition. Thus, abatement of area source emissions could be the primary way to mitigate sulfur deposition in Guangdong to meet both the provincial and national regulations of air pollution control.
