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Variations in Carbohydrate and Protein Accumulation among Spikelets at Different Positions Within a Panicle During Rice Grain Filling 被引量:2
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作者 DONG Ming-hui CHEN Pei-feng +2 位作者 XIE Yu-lin QIAO Zhong-ying YANG Jian-chang 《Rice science》 2012年第3期223-232,共10页
The accumulation dynamics of kernel components for spikelets at different positions within a rice panicle were investigated during grain filling to understand the physiological reasons for the variation of grain quali... The accumulation dynamics of kernel components for spikelets at different positions within a rice panicle were investigated during grain filling to understand the physiological reasons for the variation of grain quality.Two rice cultivars,Yangdao 6 (indica) and Yangjing 9538 (japonica),were field-grown,and the grain filling characters and contents of starch,soluble sugar,and protein of the spikelets at different positions were studied.There were significant differences in matter accumulation among spikelets at different positions during grain filling.The early-flowering spikelets presented dominance over the late-flowering spikelets in initial time and initial rate of accumulation.At the initial and mid filling stages,the contents and the rates of starch and amylose accumulation in spikelets decreased with the flowering sequence,but soluble sugar content (SSC) exhibited the opposite trend.The difference in SSC among the spikelets of Yangjing 9538 was greater than that of Yangdao 6,but amylose content in mature spikelets showed no obvious relationship to their flowering sequence.The crude protein content (CPC) of early-flowering spikelets decreased more rapidly than that of late-flowering ones at the initial filling stage,and CPC in the spikelets on the secondary branch was higher than that on the primary branch,but CPC in early-flowering ones was lower than that in late-flowering across the whole grain filling period.Grain water content (GWC) of early-flowering spikelets decreased more rapidly than that of late-flowering spikelets on the same branch at the initial and mid filling stages,especially for the top grain on each primary branch.The results suggested that poor grain filling of late-flowering spikelets may be attributed to their low biological activity rather than carbohydrate supply limitation. 展开更多
关键词 spikelet position STARCH protein accumulation dynamic variation rice grain filling
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THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS POSSIBLE MECHANISM 被引量:6
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作者 王黎娟 管兆勇 何金海 《Journal of Tropical Meteorology》 SCIE 2006年第2期113-120,共8页
Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of the relationship between the position variation of the west Pacific subtropical high (WPSH) and the apparcnt heating in June ... Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of the relationship between the position variation of the west Pacific subtropical high (WPSH) and the apparcnt heating in June 1998 based on the complete vertical vorticlty equation. It is tbund that the non-adiabatic heating plays an important role in the position variation of WPSH. In comparison with climatic mean status, the vertical change of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south side of WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to lhe south of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsula and South China Sea areas lead to the more southward position of WPSH than the mean. 展开更多
关键词 West Pacific subtropical high position variation apparent heating
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Estimation of annual variation of water vapor in the Arctic Ocean between 80°–87°N using shipborne GPS data based on kinematic precise point positioning 被引量:1
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作者 LUO Xiaowen ZHANG Tao +2 位作者 GAO Jinyao YANG Chunguo WU Zaocai 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第6期1-4,共4页
The measurement of atmospheric water vapor (WV) content and variability is important for meteorological and climatological research. A technique for the remote sensing of atmospheric WV content using ground-based Gl... The measurement of atmospheric water vapor (WV) content and variability is important for meteorological and climatological research. A technique for the remote sensing of atmospheric WV content using ground-based Global Positioning System (GPS) has become available, which can routinely achieve accuracies for integrated WV content of 1-2 kg/m2. Some experimental work has shown that the accuracy of WV measurements from a moving platform is comparable to that of (static) land-based receivers. Extending this technique into the marine environment on a moving platform would be greatly beneficial for many aspects of meteorological research, such as the calibration of satellite data, investigation of the air-sea interface, as well as forecasting and climatological studies. In this study, kinematic precise point positioning has been developed to investigate WV in the Arctic Ocean (80°-87°N) and annual variations are obtained for 2008 and 2012 that are identical to those related to the enhanced greenhouse effect. 展开更多
关键词 annual variation estimation water vapor Arctic Ocean kinematic precise point positioning
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Precise Positioning Method for Seafloor Geodetic Stations Based on the Temporal Variation of Sound Speed Structure 被引量:1
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作者 Shuang ZHAO Zhenjie WANG +3 位作者 Zhixi NIE Kaifei HE Huimin LIU Zhen SUN 《Journal of Geodesy and Geoinformation Science》 CSCD 2023年第2期81-92,共12页
At present,GNSS-Acoustic(GNSS-A)combined technology is widely used in positioning for seafloor geodetic stations.Based on Sound Velocity Profiles(SVPs)data,the equal gradient acoustic ray-tracing method is applied in ... At present,GNSS-Acoustic(GNSS-A)combined technology is widely used in positioning for seafloor geodetic stations.Based on Sound Velocity Profiles(SVPs)data,the equal gradient acoustic ray-tracing method is applied in high-precision position inversion.However,because of the discreteness of the SVPs used in the forementioned method,it ignores the continuous variation of sound velocity structure in time domain,which worsens the positioning accuracy.In this study,the time-domain variation of Sound Speed Structure(SSS)has been considered,and the cubic B-spline function is applied to characterize the perturbed sound velocity.Based on the ray-tracing theory,an inversion model of“stepwise iteration&progressive corrections”for both positioning and sound speed information is proposed,which conducts the gradual correction of seafloor geodetic station coordinates and disturbed sound velocity.The practical data was used to test the effectiveness of our method.The results show that the Root Mean Square(RMS)errors of the residual values of the traditional methods without sound velocity correction,based on quadratic polynomial correction and based on cubic B-spline function correction are 1.43 ms,0.44 ms and 0.21 ms,respectively.The inversion model with sound velocity correction can effectively eliminate the systematic error caused by the change of SSS,and significantly improve the positioning accuracy of the seafloor geodetic stations. 展开更多
关键词 GNSS-Acoustic sound speed structure temporal variation seafloor positioning
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Body Position Changes Influence Stroke Volume Variation in Mechanically Ventilated Patients with Sepsis 被引量:3
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《麻醉与监护论坛》 2012年第1期26-31,共6页
关键词 摘要 编辑部 编辑工作 读者
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Dosimetric Impact of Inter-Fraction Variation in Interstitial HDR Brachytherapy
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作者 Saravanan Kandasamy K. S. Reddy +2 位作者 Vivekanandan Nagarajan Parthasarathy Vedasoundaram Gunaseelan Karunanidhi 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2013年第4期111-116,共6页
Background: Patient setup errors in External Beam Radiotherapy (EBRT) are minimized to a great extent, due to recent technological developments but in contrary brachytherapy received least attention in inter-fraction ... Background: Patient setup errors in External Beam Radiotherapy (EBRT) are minimized to a great extent, due to recent technological developments but in contrary brachytherapy received least attention in inter-fraction catheter movement and its impact in dose delivery. This article deals with inter-fraction interstitial catheter movement and its impact in dose delivery to the target. An attempt is made to study the dosimetric impact of this variation. Objectives: The objective of the study is to evaluate the inter-fraction variation in the position of implanted interstitial applicators and to assess the dosimetric impact in interstitial High Dose Rate (HDR) brachytherapy. Materials and Methods: 55 patients treated for carcinoma tongue, breast, buccal mucosa, cervix, floor of mouth and soft tissue sarcoma over a period of 2 years (December 2011-May 2013) were considered. All the patients underwent CT scan on the next day of the implant and 3D planning was done either by Eclipse or Oncentra Master plan Treatment Planning System (TPS). Patients were treated by HDR brachytherapy remote after-loading units, either by Gamma Med iX plus or Microselectron. At the end of the last fraction, CT scan was repeated and re-planning done. The variation in position of the implanted applicators/catheters and its impact on dosimetric parameters were evaluated and analyzed. Results: The range of positional displacement of the interstitial catheters ranges from 4.5 mm to 6.8 mm. The maximum variation in prescribed dose to D90 of Clinical Target Volume was 10.88%. Conclusions: If the total duration of interstitial implant of HDR brachytherapy extends for more than a week from the day of imaging, it is recommended to do CT imaging and re-plan again. It is mandatory to suture the buttons of the implant to the skin. Edema and movement of organs (e.g., tongue) are the main cause for the positional variation of the catheters. 展开更多
关键词 HDR BRACHYTHERAPY INTERSTITIAL IMPLANT inter-fraction variatION Dosimetric variatION
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An Evaluation of Inter-Fractional Set-Up Errors in Patients Treated with Distinct Immobilization Equipment for Varying Anatomical Regions
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作者 Sibel Karaca Hamit Başaran +1 位作者 Timur Koca Ferhat Özbayrak 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2016年第2期121-129,共9页
This study aims to evaluate inter-fractional set-up errors in patients treated with distinct immobilization equipment (thermoplastic mask, knee-fix and feet-fix, wing board and vac-lok) for four anatomical regions inc... This study aims to evaluate inter-fractional set-up errors in patients treated with distinct immobilization equipment (thermoplastic mask, knee-fix and feet-fix, wing board and vac-lok) for four anatomical regions including brain, head and neck (HN), thorax and pelvis. Data of randomly selected 140 patients who were treated for four anatomical regions were obtained using Hi-Art Helical Tomotherapy (HT) system. Pre-treatment planning was based on automatic registration readings of computed tomography (CT) and mega-voltage computed tomography (MVCT) on a daily basis. Distinct immobilization equipment was used for varying anatomical regions. Individual mean set-up error (M), systematic error (Σ), and random error (σ) values were calculated through daily translational and rotational deviation values. The size of translational, systematic and random error was 1.31 - 4.93 mm for brain, 2.28 - 4.88 mm for HN, 4.04 - 9.90 mm for thorax, and 6.34 - 14.68 mm for pelvis. Rotational values were as follows: 0.06&deg - 0.73&deg for brain, 0.42&deg - 0.6&deg for HN, 0.48&deg - 1.14&deg for thorax and 0.65&deg - 1.05&deg for pelvis. The highest translational, systematic and random error value was obtained from the pelvic regional. The highest standard and random error value in pitch and roll was produced in the rotational direction of the pelvis (0.05° and 0.71°), while the highest error value in yaw was (1.14°) produced from thorax. Inter-fractional set-up errors were most commonly produced in the pelvis, followed by thorax. Our study results suggest that the highest systematic and random errors are found for thorax and pelvis. Distinct immobilization equipment was important in these results. Safety margins around the clinical target volume (CTV) are changeable for different anatomical regions. A future work could be developed to new equipment for immobilization because of the reduced margins CTV. 展开更多
关键词 Hi-Art Helical Tomotherapy IGRT inter-fractional Set-Up Errors Rotational variation Translational variation
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MULTIPLICITY AND CONCENTRATION BEHAVIOUR OF POSITIVE SOLUTIONS FOR SCHRDINGER-KIRCHHOFF TYPE EQUATIONS INVOLVING THE p-LAPLACIAN IN R^N 被引量:3
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作者 贾慧芳 李工宝 《Acta Mathematica Scientia》 SCIE CSCD 2018年第2期391-418,共28页
In this article, we study the multiplicity and concentration behavior of positive solutions for the p-Laplacian equation of SchrSdinger-Kirchhoff type -εpM(εp-N∫RN|△u|p)△pu+v(x|u|p-2u=f(u)in RN, where ... In this article, we study the multiplicity and concentration behavior of positive solutions for the p-Laplacian equation of SchrSdinger-Kirchhoff type -εpM(εp-N∫RN|△u|p)△pu+v(x|u|p-2u=f(u)in RN, where △p is the p-Laplacian operator, 1 〈 p 〈 N, M : R+ → R+ and V : RN →R+ are continuous functions, ε is a positive parameter, and f is a continuous function with subcritical growth. We assume that V satisfies the local condition introduced by M. del Pino and P. Felmer. By the variational methods, penalization techniques, and Lyusternik- Schnirelmann theory, we prove the existence, multiplicity, and concentration of solutions for the above equation. 展开更多
关键词 SchrSdinger-Kirchhoff type equation variational methods multiple positive solutions concentrating solution penalization method
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POSITIVE SOLUTIONS FOR WEAKLY COUPLED NONLINEAR ELLIPTIC SYSTEMS 被引量:1
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作者 龙静 杨健夫 《Acta Mathematica Scientia》 SCIE CSCD 2010年第5期1577-1592,共16页
In this article, we consider the existence of positive solutions for weakly coupled nonlinear elliptic systems {-△u+u=(1+a(x))|u|P-1u+μ|u|a-2u|v|β+λv in Rn,-△u+u=(1+b(x))|v|p-1v+μ|u|a|... In this article, we consider the existence of positive solutions for weakly coupled nonlinear elliptic systems {-△u+u=(1+a(x))|u|P-1u+μ|u|a-2u|v|β+λv in Rn,-△u+u=(1+b(x))|v|p-1v+μ|u|a|v|β-2v+λu in Rn To find nontrivial solutions, we first investigate autonomous systems. In this case, results of bifurcation from semi-trivial solutions are obtained by the implicit function theorem. Next, the existence of positive solutions of problem (0.1) is obtained by variational methods. 展开更多
关键词 Elliptic system in RN positive solution BIFURCATION variational method
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Robust SLAM localization method based on improved variational Bayesian filtering 被引量:1
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作者 Zhai Hongqi Wang Lihui +1 位作者 Cai Tijing Meng Qian 《Journal of Southeast University(English Edition)》 EI CAS 2022年第4期340-349,共10页
Aimed at the problem that the state estimation in the measurement update of the simultaneous localization and mapping(SLAM)method is incorrect or even not convergent because of the non-Gaussian measurement noise,outli... Aimed at the problem that the state estimation in the measurement update of the simultaneous localization and mapping(SLAM)method is incorrect or even not convergent because of the non-Gaussian measurement noise,outliers,or unknown and time-varying noise statistical characteristics,a robust SLAM method based on the improved variational Bayesian adaptive Kalman filtering(IVBAKF)is proposed.First,the measurement noise covariance is estimated using the variable Bayesian adaptive filtering algorithm.Then,the estimated covariance matrix is robustly processed through the weight function constructed in the form of a reweighted average.Finally,the system updates are iterated multiple times to further gradually correct the state estimation error.Furthermore,to observe features at different depths,a feature measurement model containing depth parameters is constructed.Experimental results show that when the measurement noise does not obey the Gaussian distribution and there are outliers in the measurement information,compared with the variational Bayesian adaptive SLAM method,the positioning accuracy of the proposed method is improved by 17.23%,20.46%,and 17.76%,which has better applicability and robustness to environmental disturbance. 展开更多
关键词 underwater navigation and positioning non-Gaussian distribution time-varying noise variational Bayesian method simultaneous localization and mapping(SLAM)
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EXISTENCE OF POSITIVE SOLUTIONS TO QUASI-LINEAR EQUATION INVOLVING CRITICAL SOBOLEV-HARDY EXPONENT
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作者 康东升 《Acta Mathematica Scientia》 SCIE CSCD 2004年第4期639-644,共6页
This paper is concerned with the quasi-linear equation with critical Sobolev-Hardy exponent whereΩ(?)RN(N(?)3)is a smooth bounded domain,0∈Ω,0(?)s<p,1<p<N,p(s):=p(N-s)/N-p is the critical Sobolev-Hardy exp... This paper is concerned with the quasi-linear equation with critical Sobolev-Hardy exponent whereΩ(?)RN(N(?)3)is a smooth bounded domain,0∈Ω,0(?)s<p,1<p<N,p(s):=p(N-s)/N-p is the critical Sobolev-Hardy exponent,λ>0,p(?)r<p,p:=Np/N-p is the critical Sobolev exponent,μ>,0(?)t<p,p(?)q<p(t)=p(N-t)/N-p.The existence of a positive solution is proved by Sobolev-Hardy inequality and variational method. 展开更多
关键词 positive solution quasi-linear equation critical Sobolev-Hardy exponent variational method
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MULTIPLICITY OF POSITIVE SOLUTIONS FOR A CLASS OF CONCAVE-CONVEX ELLIPTIC EQUATIONS WITH CRITICAL GROWTH
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作者 廖家锋 蒲洋 唐春雷 《Acta Mathematica Scientia》 SCIE CSCD 2018年第2期497-518,共22页
In this article, the following concave and convex nonlinearities elliptic equations involving critical growth is considered,{-△u=g(x)|u|2*-2u+λf(x)|u|q-2u,x∈Ω u=0,x∈δΩ where Ω RN(N ≥ 3) is an op... In this article, the following concave and convex nonlinearities elliptic equations involving critical growth is considered,{-△u=g(x)|u|2*-2u+λf(x)|u|q-2u,x∈Ω u=0,x∈δΩ where Ω RN(N ≥ 3) is an open bounded domain with smooth boundary, 1 〈 q 〈 2, λ 〉 0. 2*= 2N/N-2 is the critical Sobolev exponent, f ∈L2*/2N/N-2 is nonzero and nonnegative, and g E (Ω) is a positive function with k local maximum points. By the Nehari method and variational method, k + 1 positive solutions are obtained. Our results complement and optimize the previous work by Lin [MR2870946, Nonlinear Anal. 75(2012) 2660-26711. 展开更多
关键词 Semilinear elliptic equations critical growth positive solutions Nehari method variational method
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Positive Radial Solutions for a Class of Semilinear Elliptic Problems Involving Critical Hardy-Sobolev Exponent and Hardy Terms
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作者 Yong-Yi Lan 《Journal of Applied Mathematics and Physics》 2017年第11期2205-2217,共13页
In this paper, we investigate the solvability of a class of semilinear elliptic equations which are perturbation of the problems involving critical Hardy-Sobolev exponent and Hardy singular terms. The existence of at ... In this paper, we investigate the solvability of a class of semilinear elliptic equations which are perturbation of the problems involving critical Hardy-Sobolev exponent and Hardy singular terms. The existence of at least a positive radial solution is established for a class of semilinear elliptic problems involving critical Hardy-Sobolev exponent and Hardy terms. The main tools are variational method, critical point theory and some analysis techniques. 展开更多
关键词 HARDY SINGULAR TERMS Hardy-Sobolev EXPONENT positive Radial Solution Perturbation Method variatIONAL Approach
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Ultrasonographic identification of lateral femoral cutaneous nerve anatomical variation in persistent meralgia paresthetica:A case report
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作者 Hyeong-Woo Park Kyung-Suk Ji +2 位作者 Jun-Hyung Kim Li-Na Kim Kang-Wook Ha 《World Journal of Clinical Cases》 SCIE 2023年第31期7699-7705,共7页
BACKGROUND Meralgia paresthetica(MP)is an entrapment mononeuropathy of the lateral femoral cutaneous nerve(LFCN).Although structural abnormalities in nerve tissues can be confirmed using ultrasonography,this is not ro... BACKGROUND Meralgia paresthetica(MP)is an entrapment mononeuropathy of the lateral femoral cutaneous nerve(LFCN).Although structural abnormalities in nerve tissues can be confirmed using ultrasonography,this is not routinely performed.CASE SUMMARY Herein,we present the case of a 52-year-old woman who developed MP after laparoscopic gynecological surgery.The patient was referred to our clinic from an obstetrics and gynecology clinic with symptoms of numbness and a tingling sensation in the left anterolateral thigh,which developed after surgery performed 5 mo earlier.Tests were performed to assess the disease status and determine the underlying causes.Ultrasonographic examination revealed an anatomical variation,where the left LFCN was entrapped within the inguinal ligament.This case suggests that performing ultrasonographic examination before and after surgery in the lithotomy position could help prevent MP.CONCLUSION This case demonstrates the value of ultrasonography in detecting anatomical variation and diagnosing persistent MP.Ultrasonography should be considered an adjunct to electromyography for optimal MP management.Further,this case would help other clinicians determine patient prognosis and decide on targeted treatment strategies. 展开更多
关键词 Lateral femoral cutaneous nerve Anatomical variation Meralgia paresthetica Lithotomy position ULTRASONOGRAPHY Case report
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Existence and Multiplicity of Positive Solutions for a Coupled Fourth-Order System of Kirchhoff Type
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作者 LI Zhen-hui XU Li-ping 《Chinese Quarterly Journal of Mathematics》 2021年第1期49-66,共18页
In this paper,we study a coupled fourth-order system of Kirchhoff type.Under appropriate hypotheses of V_(i)(x)for i=1,2,f and g,we obtained two main existence theorems of weak solutions for the problem by variational... In this paper,we study a coupled fourth-order system of Kirchhoff type.Under appropriate hypotheses of V_(i)(x)for i=1,2,f and g,we obtained two main existence theorems of weak solutions for the problem by variational methods.Some recent results are extended. 展开更多
关键词 A coupled fourth-order system of Kirchhoff type positive solutions Lack of compactness variational methods
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知识变异视角下学科知识创新生长现状分析——以引文分析领域为例
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作者 李长玲 栾锟 +2 位作者 王浩 徐卫杰 王庆华 《情报理论与实践》 CSSCI 北大核心 2024年第12期89-96,共8页
[目的/意义]知识变异是指两个或多个学科的知识基因重新组合产生创新知识的过程,基于知识变异视角分析学科知识创新生长现状,对于在大科学背景下把握学科发展现状、总结知识创新生长规律、探测复杂学术问题的解决具有重要意义。[方法/过... [目的/意义]知识变异是指两个或多个学科的知识基因重新组合产生创新知识的过程,基于知识变异视角分析学科知识创新生长现状,对于在大科学背景下把握学科发展现状、总结知识创新生长规律、探测复杂学术问题的解决具有重要意义。[方法/过程]定义学科交叉背景下知识创新生长的结果表现为跨学科知识生长点的产生,位于不同引用位置的跨学科知识对施引知识创新生长的刺激程度存在差异。因此,将文献引用位置划分为引言、综述、方法、讨论、结论5个部分并赋予不同的权重,从知识合作强度与知识合作有效性两方面构建跨学科知识生长点创新程度测度模型,测度知识变异程度及创新生长现状,并进行类型划分。[结果/结论]以引文分析领域为例进行实证分析,发现在这个领域中的核心专业知识与应用方向知识更容易受到跨学科输入知识的刺激。其中,理论概念类跨学科知识的刺激作用需要量的积累,方法类跨学科知识刺激快速高效,技术类跨学科知识的专业性差异会影响其刺激效果。 展开更多
关键词 知识变异 跨学科 知识创新生长 引用位置 引文分析
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井下电力电缆故障定位研究
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作者 商立群 张少强 +2 位作者 荣相 刘江山 王越 《工矿自动化》 CSCD 北大核心 2024年第2期130-137,共8页
针对传统井下电力电缆故障定位方法依赖主观参数选择和抗噪性能较差,无法满足强噪声背景下井下电力电缆故障精确定位要求的问题,提出了一种基于樽海鞘群算法(SSA)优化变分模态分解(VMD)并结合改进型Teager能量算子(NTEO)的井下电力电缆... 针对传统井下电力电缆故障定位方法依赖主观参数选择和抗噪性能较差,无法满足强噪声背景下井下电力电缆故障精确定位要求的问题,提出了一种基于樽海鞘群算法(SSA)优化变分模态分解(VMD)并结合改进型Teager能量算子(NTEO)的井下电力电缆故障定位方法。针对VMD在信号分解上存在的模态混叠、过分解和欠分解问题,采用SSA以模糊熵为适应度函数对VMD模态数K和惩罚因子α2个参数进行优化,得到更能反映故障特征信息的本征模态函数;采用NTEO对本征模态函数进行首波波头标定,得到首末两端的波头到达时刻,根据双端测距法得出故障位置。采用PSCAD/EMTDC进行井下电力电缆故障仿真,模拟具有强背景噪声的井下故障信号,结果表明:①在理想电流信号中加入9,12 dB噪声后,SSA-VMD的信噪比最低,皮尔逊相关系数最大,说明SSA-VMD在最大程度降噪的同时,能很好地保留信号的特征信息。②在不同过渡电阻下,SSA-VMD-NTEO的定位精度较高。③在不同故障相角下,SSA-VMD-NTEO在采样点上出现不同,但定位位置没有改变,依旧保持较高的定位精度。④在不同故障距离下,SSA-VMD-NTEO均能保证较高的定位精度。⑤在井下较大噪声和10 MHz采样频率下,SSA-VMD-NTEO较小波模极大值和VMD+NTEO 2种方法的定位精度具有明显优势。 展开更多
关键词 井下电力电缆 故障定位 樽海鞘群算法 变分模态分解 TEAGER能量算子 首波波头标定
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一类超线性双调和方程正解的存在性
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作者 吉蕾 《安徽大学学报(自然科学版)》 CAS 北大核心 2024年第5期12-17,共6页
研究以下双调和方程{Δ^(2)u+cΔu=f(x,u),x∈Ω,Δu=u=0,x∈∂Ω,其中Ω∈R^(N)是有界开集,其边界∂Ω光滑.c∈R,f:Ω×R→R是Caratheodory函数.当非线性项f(x,u)在无穷远处为超线性时,通过山路引理和强极大值原理获得了该方程的正解... 研究以下双调和方程{Δ^(2)u+cΔu=f(x,u),x∈Ω,Δu=u=0,x∈∂Ω,其中Ω∈R^(N)是有界开集,其边界∂Ω光滑.c∈R,f:Ω×R→R是Caratheodory函数.当非线性项f(x,u)在无穷远处为超线性时,通过山路引理和强极大值原理获得了该方程的正解,所设条件弱于相关文献中的条件,使得非线性项更具一般性,从而推广了相关文献中关于超线性的结果. 展开更多
关键词 双调和 超线性 变分方法 正解
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南京大气颗粒物化学组分的粒径分布和来源解析
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作者 卢睿霖 曹芳 +2 位作者 林煜棋 吴长流 章炎麟 《生态环境学报》 CSCD 北大核心 2024年第7期1079-1088,共10页
大气颗粒物中化学组分的粒径分布与其来源、形成过程、环境及健康效应密切相关。而过去对不同季节颗粒物的粒径分布特征,以及不同来源对粗、细颗粒物的贡献的研究相对较少。于2022年12月(冬季)和2023年8月(夏季)在南京采集了大气分粒径... 大气颗粒物中化学组分的粒径分布与其来源、形成过程、环境及健康效应密切相关。而过去对不同季节颗粒物的粒径分布特征,以及不同来源对粗、细颗粒物的贡献的研究相对较少。于2022年12月(冬季)和2023年8月(夏季)在南京采集了大气分粒径颗粒物样品,分析了粗颗粒物(PM_(2.1-10))和细颗粒物(PM_(2.1))中碳质组分和主要水溶性无机离子的粒径分布和季节变化,运用正定矩阵因子分解模型(Positive Matrix Factorization,PMF)进行PM_(2.1-10)和PM_(2.1)的源解析。结果表明,在粒径分布特征上,冬夏两季有机碳(OC)、元素碳(EC)、水溶性有机碳(WSOC)的平均浓度呈双峰型分布。SO_(4)^(2-)和NO_(3)^(-)的季节平均浓度均为双峰型分布。NH_(4)^(+)主要分布在细颗粒物中,季节平均浓度呈单峰型分布,冬夏季均在0.43-0.65μm出现峰值。在季节变化上,颗粒物中除Na^(+)和SO_(4)^(2-)外的主要化学组分浓度均在冬季高于夏季。冬夏两季Ca^(2+)、Mg^(2+)主要集中在粗颗粒物中。根据PMF模型解析结果,南京大气颗粒物主要有4类来源贡献,即交通源、二次生成、生物质燃烧和扬尘源。PM_(2.1)主要来自二次生成和生物质燃烧源,冬夏季分别贡献了65.7%和61.0%,其中冬季生物质燃烧和二次硝酸盐的贡献占主导地位,而夏季主要来自二次硫酸盐的贡献。冬季PM_(2.1-10)主要来自交通源(41.8%),夏季则主要来自生物质燃烧和硝酸盐的二次生成贡献(43.9%)。研究探讨了大气颗粒物的化学组分的粒径分布特征、季节差异及来源,可为制定有针对性的大气污染防控措施提供科学依据。 展开更多
关键词 大气颗粒物 碳质气溶胶 水溶性离子 粒径分布 季节差异 正定矩阵因子分解模型
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基于多种策略改进的鲸鱼优化算法
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作者 戴春雨 马廉洁 +1 位作者 蒋涵存 李红双 《计算机工程与科学》 CSCD 北大核心 2024年第9期1635-1647,共13页
针对标准鲸鱼优化算法收敛速度慢、搜索与开发不平衡、种群之间信息交流匮乏、容易陷入局部最优的问题,提出了一种改进算法。首先,采用Tent混沌映射提高初始种群的分布均匀性,并引入非线性收敛因子,提升算法前期的全局搜索和中后期局部... 针对标准鲸鱼优化算法收敛速度慢、搜索与开发不平衡、种群之间信息交流匮乏、容易陷入局部最优的问题,提出了一种改进算法。首先,采用Tent混沌映射提高初始种群的分布均匀性,并引入非线性收敛因子,提升算法前期的全局搜索和中后期局部开发的能力,协调了搜索与开发的转换机制。然后,将种群的平均位置向量引入随机搜索过程中,有效改善个体与种群之间缺乏信息交流的问题。接着,将自适应惯性权重引入位置更新公式中,以加快算法的收敛速度,提高求解精度。最后,利用柯西算子对陷入局部最优的个体进行变异扰动。通过15个基准测试函数对改进算法进行仿真实验,实验结果表明,改进后的鲸鱼优化算法具有良好的性能,并通过Wilcoxon秩和检验证明了改进算法的有效性。 展开更多
关键词 Tent混沌映射 非线性因子 平均位置 自适应权重 柯西变异
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