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
In this paper, we study the joint limit distributions of point processes of exceedances and partial sums of multivariate Gaussian sequences and show that the point processes and partial sums are asymptotically indepen...In this paper, we study the joint limit distributions of point processes of exceedances and partial sums of multivariate Gaussian sequences and show that the point processes and partial sums are asymptotically independent under some mild conditions. As a result, for a sequence of standardized stationary Gaussian vectors, we obtain that the point process of exceedances formed by the sequence （centered at the sample mean） converges in distribution to a Poisson process and it is asymptotically independent of the partial sums. The asymptotic joint limit distributions of order statistics and partial sums are also investigated under different conditions.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
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
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
Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results a...Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results are acquired. The truncation level adopted in probabilistic seismic hazard analysis （PSHA） should be determined by an aleatory uncertainty model （i.e., distribution model） of ground motions and the possible maximum and minimum ground motion values of a specific earthquake. However, at the present time, it is impossible to establish the upper bound model for ground motions based on the source characteristics and/or ground motion propagation. McGuire suggested a truncation level be fixed at a number of = 6, or the distribution of residuals be truncated in such a manner that site intensity cannot be greater than the epicenter intensity. This study aims to find a reasonable and feasible truncation level to be used in PSHA when the physical mechanism is not available to find the extreme ground motion. A mathematical analysis of the influence of the truncation level on PSHA, case studies of sites in different seismotectonic settings, and a distribution analysis of ground motion residuals are conducted in this study. It is concluded that = 4 is the minimum acceptable value for engineering applications for APEs within 0.002 to 10-4, and for low APEs, such as 10-5 and 10-6, the value of should be no less than 5 in most regions of China.展开更多
The performance-based passive control analysis of the Maxwell dampers between one 10-story and one 6-story adjacent RC frames is conducted in this work.Not only the optimal parameters but also the optimal arrangements...The performance-based passive control analysis of the Maxwell dampers between one 10-story and one 6-story adjacent RC frames is conducted in this work.Not only the optimal parameters but also the optimal arrangements of the Maxwell dampers are proposed based on the optimal target of making the total exceeding probability of the adjacent structures to be minimal.The applicability of the analytical expressions of the Maxwell damper damping parameters under different seismic performance targets are firstly examined and then the preferable damping parameters of the Maxwell dampers are proposed through the extensive parametric studies.Furthermore,the optimal arranging positions and optimal arranging numbers of the Maxwell dampers between the adjacent buildings are derived based on a large number of seismic fragility analyses,as well.The general arranging laws of the Maxwell dampers between the adjacent buildings are generated based on the discussion of the theoretical method through the simplified plane model.The optimal parameters and optimal arrangement of the Maxwell dampers presented make both the adjacent structures have preferable controlled effects under each seismic performance target which can satisfy the requirements of multi-performance seismic resistance of the modern seismic codes.展开更多
Organic solar cells(OSCs)show a promising commercialization prospect with their power conversion efficiencies(PCEs)exceeding 18%[1−6].Among various types of OSCs,all-polymer solar cells(all-PSCs)with a physical blend ...Organic solar cells(OSCs)show a promising commercialization prospect with their power conversion efficiencies(PCEs)exceeding 18%[1−6].Among various types of OSCs,all-polymer solar cells(all-PSCs)with a physical blend of p-and n-type polymer as the active layer to harvest solar irradiation attract growing attention due to their unique advantages like excellent morphological stability,and mechanical durability[7].展开更多
Organic–inorganic hybrid perovskite solar cells(PSCs)have been recognized as a promising and cost-effective photovoltaic technology with the power conversion efficiency(PCE) exceeding 25%[1–3]. The high efficiency i...Organic–inorganic hybrid perovskite solar cells(PSCs)have been recognized as a promising and cost-effective photovoltaic technology with the power conversion efficiency(PCE) exceeding 25%[1–3]. The high efficiency is attributed to the exceptional optoelectronic properties, such as high absorption coefficient, long carrier diffusion length, low non-radiative recombination rate, and so on[4–7].展开更多
With a heralded single photon source(HSPS), a measurement-device-independent quantum key distribution(MDIQKD) protocol is proposed, combined with a three-intensity decoy-state method. HSPS has the two-mode characteris...With a heralded single photon source(HSPS), a measurement-device-independent quantum key distribution(MDIQKD) protocol is proposed, combined with a three-intensity decoy-state method. HSPS has the two-mode characteristic, one mode is used as signal mode, and the other is used as heralded mode to reduce the influence of the dark count. The lower bound of the yield and the upper bound of the error rate are deduced and the performance of the MDI-QKD protocol with an HSPS is analyzed. The simulation results show that the MDI-QKD protocol with an HSPS can achieve a key generation rate and a secure transmission distance which are close to the theoretical limits of the protocol with a single photon source(SPS). Moreover, the key generation rate will improve with the raise of the senders' detection efficiency. The key generation rate of the MDI-QKD protocol with an HSPS is a little less than that of the MDI-QKD protocol with a weak coherent source(WCS) in the close range, but will exceed the latter in the far range. Furthermore, a farther transmission distance is obtained due to the two-mode characteristic of HSPS.展开更多
Ultra high-velocity collisionless shocks are generated using an ultra-intense laser interacting with foil-gas target,which consists of copper foil and helium gas.The energy of helium ions accelerated by shock and the ...Ultra high-velocity collisionless shocks are generated using an ultra-intense laser interacting with foil-gas target,which consists of copper foil and helium gas.The energy of helium ions accelerated by shock and the proton probing image of the shock electrostatic field show that the shock velocity is 0.02c,where c is the light speed.The numerical and theory studies indicate that the collisionless shock velocity exceeding 0.1c can be generated by a laser pulse with picosecond duration and an intensity of 1020 W/cm2.This system may be relevant to the study of mildly relativistic velocity collisionless shocks in astrophysics.展开更多
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 National Natural Science Foundation of China(Grant No.11171275)the Program for Excellent Talents in Chongqing Higher Education Institutions(Grant No.120060-20600204)supported by the Swiss National Science Foundation Project(Grant No.200021-134785)
文摘In this paper, we study the joint limit distributions of point processes of exceedances and partial sums of multivariate Gaussian sequences and show that the point processes and partial sums are asymptotically independent under some mild conditions. As a result, for a sequence of standardized stationary Gaussian vectors, we obtain that the point process of exceedances formed by the sequence （centered at the sample mean） converges in distribution to a Poisson process and it is asymptotically independent of the partial sums. The asymptotic joint limit distributions of order statistics and partial sums are also investigated under different conditions.
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.
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 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.
基金Program of Seismic Ground Motion Parameter Zonation Map of Chinathe Basic Research Fund of the Institute of Geophysics Under Grant No.DQJB11C18the Special Funds for Science and Technology Research Under Grant No.200708003
文摘Recent studies on assessment of a very low annual probability of exceeding （APE） ground motions, 10-4 or less, have highlighted the importance of the upper bound of ground motions when very low probability results are acquired. The truncation level adopted in probabilistic seismic hazard analysis （PSHA） should be determined by an aleatory uncertainty model （i.e., distribution model） of ground motions and the possible maximum and minimum ground motion values of a specific earthquake. However, at the present time, it is impossible to establish the upper bound model for ground motions based on the source characteristics and/or ground motion propagation. McGuire suggested a truncation level be fixed at a number of = 6, or the distribution of residuals be truncated in such a manner that site intensity cannot be greater than the epicenter intensity. This study aims to find a reasonable and feasible truncation level to be used in PSHA when the physical mechanism is not available to find the extreme ground motion. A mathematical analysis of the influence of the truncation level on PSHA, case studies of sites in different seismotectonic settings, and a distribution analysis of ground motion residuals are conducted in this study. It is concluded that = 4 is the minimum acceptable value for engineering applications for APEs within 0.002 to 10-4, and for low APEs, such as 10-5 and 10-6, the value of should be no less than 5 in most regions of China.
基金Projects(51408443,51178203)supported by the National Natural Science Foundation of ChinaProject(K201511)supported by the Science Foundation of Wuhan Institute of Technology,China
文摘The performance-based passive control analysis of the Maxwell dampers between one 10-story and one 6-story adjacent RC frames is conducted in this work.Not only the optimal parameters but also the optimal arrangements of the Maxwell dampers are proposed based on the optimal target of making the total exceeding probability of the adjacent structures to be minimal.The applicability of the analytical expressions of the Maxwell damper damping parameters under different seismic performance targets are firstly examined and then the preferable damping parameters of the Maxwell dampers are proposed through the extensive parametric studies.Furthermore,the optimal arranging positions and optimal arranging numbers of the Maxwell dampers between the adjacent buildings are derived based on a large number of seismic fragility analyses,as well.The general arranging laws of the Maxwell dampers between the adjacent buildings are generated based on the discussion of the theoretical method through the simplified plane model.The optimal parameters and optimal arrangement of the Maxwell dampers presented make both the adjacent structures have preferable controlled effects under each seismic performance target which can satisfy the requirements of multi-performance seismic resistance of the modern seismic codes.
基金financially supported by the National Key Research and Development Program of China(2017YFA0206600)Guangdong Innovative and Entrepreneurial Research Team Program(2019ZT08L075)+2 种基金Open Funds of State Key Laboratory of Fine Chemicals(KF1901)the Fundamental Research Funds for the Central Universities(D2190310)the National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support。
文摘Organic solar cells(OSCs)show a promising commercialization prospect with their power conversion efficiencies(PCEs)exceeding 18%[1−6].Among various types of OSCs,all-polymer solar cells(all-PSCs)with a physical blend of p-and n-type polymer as the active layer to harvest solar irradiation attract growing attention due to their unique advantages like excellent morphological stability,and mechanical durability[7].
基金supported by the National Natural Science Foundation of China (61774046)the National Key Research and Development Program of China (2017YFA0206600)the National Natural Science Foundation of China (51773045, 21772030, 51922032, and 21961160720) for financial support。
文摘Organic–inorganic hybrid perovskite solar cells(PSCs)have been recognized as a promising and cost-effective photovoltaic technology with the power conversion efficiency(PCE) exceeding 25%[1–3]. The high efficiency is attributed to the exceptional optoelectronic properties, such as high absorption coefficient, long carrier diffusion length, low non-radiative recombination rate, and so on[4–7].
基金supported by the National Natural Science Foundation of China(No.61302099)
文摘With a heralded single photon source(HSPS), a measurement-device-independent quantum key distribution(MDIQKD) protocol is proposed, combined with a three-intensity decoy-state method. HSPS has the two-mode characteristic, one mode is used as signal mode, and the other is used as heralded mode to reduce the influence of the dark count. The lower bound of the yield and the upper bound of the error rate are deduced and the performance of the MDI-QKD protocol with an HSPS is analyzed. The simulation results show that the MDI-QKD protocol with an HSPS can achieve a key generation rate and a secure transmission distance which are close to the theoretical limits of the protocol with a single photon source(SPS). Moreover, the key generation rate will improve with the raise of the senders' detection efficiency. The key generation rate of the MDI-QKD protocol with an HSPS is a little less than that of the MDI-QKD protocol with a weak coherent source(WCS) in the close range, but will exceed the latter in the far range. Furthermore, a farther transmission distance is obtained due to the two-mode characteristic of HSPS.
基金Supported by the Science Challenge Project under Grant Nos TZ2018005 and TZ2016005the National Key Research and Development Program of China under Grant No 2016YFA0401100
文摘Ultra high-velocity collisionless shocks are generated using an ultra-intense laser interacting with foil-gas target,which consists of copper foil and helium gas.The energy of helium ions accelerated by shock and the proton probing image of the shock electrostatic field show that the shock velocity is 0.02c,where c is the light speed.The numerical and theory studies indicate that the collisionless shock velocity exceeding 0.1c can be generated by a laser pulse with picosecond duration and an intensity of 1020 W/cm2.This system may be relevant to the study of mildly relativistic velocity collisionless shocks in astrophysics.
