期刊文献+
共找到13篇文章
< 1 >
每页显示 20 50 100
磁极性反转线附近黑子半影纤维的形态
1
作者 洪琴芳 张柏荣 王洪照 《云南天文台台刊》 CSCD 1996年第2期13-20,共8页
本文对8个活动区极性反转线(中性线)附近黑子半影纤维的形态进行了分析得出:1)具有强δ磁结构的活动区,穿过主要异极性黑子间的中性线近旁半影纤维或多或少地与中性线平行(交角小于30°),有关黑子半影呈旋涡形态;2)... 本文对8个活动区极性反转线(中性线)附近黑子半影纤维的形态进行了分析得出:1)具有强δ磁结构的活动区,穿过主要异极性黑子间的中性线近旁半影纤维或多或少地与中性线平行(交角小于30°),有关黑子半影呈旋涡形态;2)由新浮现发展形成的δ结构区,异级黑子在大黑子边缘或与大.黑子本影之间有一段距离,中性线两边的半影纤维有序排列,走向与中性线斜交,有关黑子呈弱的旋涡形态。3)对于较稳定的极群,N、S极性间的宽窄不一的半影稀疏区,中性线沿该区经过,两旁半影松散齿状,走向与中性线大体垂直,相反极性本影间距较远。 展开更多
关键词 太阳 黑子半影 磁极性线 半影纤维
下载PDF
基于支持向量机的太阳磁场活动区极性反转线位置的探测 被引量:2
2
作者 王强 郑胜 +4 位作者 邓元勇 黄宇 黎辉 甘为群 苏江涛 《天文学报》 CSCD 北大核心 2020年第4期107-114,共8页
太阳磁场的极性反转线(Polarity Inversion Line,PIL)是研究太阳活动、分析太阳磁场结构演变和预测太阳耀斑最重要的日面特征之一.磁场极性反转的位置是太阳耀斑和暗条可能出现的位置."先进天基太阳天文台(ASO-S)"是中国首颗... 太阳磁场的极性反转线(Polarity Inversion Line,PIL)是研究太阳活动、分析太阳磁场结构演变和预测太阳耀斑最重要的日面特征之一.磁场极性反转的位置是太阳耀斑和暗条可能出现的位置."先进天基太阳天文台(ASO-S)"是中国首颗空间太阳专用观测卫星,其搭载的"全日面矢量磁像仪(Full-Disk Vector Magnetograph,FMG)"主要任务是探测高空间、高时间分辨率的全日面矢量磁场.为了提高观测数据使用效率、快速监测太阳活动水平、提高太阳耀斑与日冕物质抛射的预报水平以及更好地服务于FMG数据处理与分析系统,采用了图像自动识别与处理技术,更加精确有效地检测极性反转线.从支持向量机(Support Vector Machine,SVM)的模型出发,将极性反转线位置的探测问题转化为一个模式识别中的二分类问题,提出了一种基于支持向量机的极性反转线检测算法,自动探测与识别太阳动力学天文台(Solar Dynamics Observatory,SDO)日震和磁成像仪(Helioseismic and Magnetic Imager,HMI)磁图的极性反转线位置.与现有算法的对比结果表明,此算法可以精确直观地检测太阳活动区的极性反转线. 展开更多
关键词 太阳:磁场 极性线 支持向量机 核函数
下载PDF
嵌入式人机界面中的键盘及其接口设计 被引量:6
3
作者 怯肇乾 《单片机与嵌入式系统应用》 2006年第4期24-27,共4页
对键盘及其接口设计,有很多常见的规范设计方法和新的设计思路。文中总结常见的键盘及其接口设计的方法,着重阐述现代嵌入式人机界面中键盘及其接口设计的原理和特点,对比说明各种键盘及其接口设计方法的优劣和应用特点。
关键词 扫描 编码 线反转 可鳊程逻辑器件 电荷移感测 键盘及其接口
下载PDF
Inverse Dynamics of Delta Robot Based on the Principle of Virtual Work 被引量:5
4
作者 赵永杰 杨志永 黄田 《Transactions of Tianjin University》 EI CAS 2005年第4期268-273,共6页
A systematic methodology for solving the inverse dynamics of the Delta robot is presented.First,the inverse kinematics is solved based on the vector method.A new form of the Jacobi matrix formulized by the vectors is ... A systematic methodology for solving the inverse dynamics of the Delta robot is presented.First,the inverse kinematics is solved based on the vector method.A new form of the Jacobi matrix formulized by the vectors is obtained so the three types kinematics singularities namely inverse, direct and combined types, can be identified with the physical meaning.Then based on the principle of virtual work, a methodology for driving the dynamical equations of motion is developed.Meanwhile the whole actuating torques, the torques caused by the gravity, the velocity and the acceleration are computed respectively in the numerical example. Results show that torque caused by the acceleration term is much bigger than the other two terms.This approach leads to efficient algorithms since the constraint forces and moments of the robot system have been eliminated from the equations of motion and there is no differential equation for the whole procedure when the principle of virtual work is applied to solving the inverse dynamical problem. 展开更多
关键词 Jacobi matrix: parallel robot inverse dynamics principle of virtual work
下载PDF
Extraction of potassium from K-feldspar via the CaCl_2 calcination route 被引量:9
5
作者 袁博 李春 +5 位作者 梁斌 吕莉 岳海荣 绳昊一 叶龙泼 谢和平 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第9期1557-1564,共8页
The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-fe... The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl.As much as approximately 41% of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91% in 40 min, while the extraction was reduced to only 22% at the theoretical mass ratio of 0.2. Optimal process conditions are as follows: ore particle size of 50–75 μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min.The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the conversion reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min. 展开更多
关键词 K-feldspar Calcium chloride Potassium extraction Calcination
下载PDF
Contrast enhancement of medical ultrasound imaging with reversal phase-inversion pulse technology 被引量:1
6
作者 李琴 谭冠政 A.S.M.Libda 《Journal of Central South University》 SCIE EI CAS 2013年第3期696-701,共6页
A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the ... A new ultrasound contrast imaging technique was proposed for eliminating the harmonic components from the emission signal transmitted by the broadband ultrasonic system.Reversal phase-inversion pulse was used for the first time to separate the contrast harmonics from the harmonics in the emission signal to improve the detection of contrast micro-bubbles.Based on the nonlinear acoustic theory of finite-amplitude effects and the associated distortion of the propagating wave,the Bessel-Fubini series model was applied to describe the nonlinear propagation effects of the reversal phase-inversion pulse,and the Church's equation for zero-thickness encapsulation model was used to produce the scattering-pulse of the bubble.For harmonic imaging,the experiment was performed using a 64-element linear array,which was simulated by Field II.The results show that the harmonic components from the emission signal can be completely cancelled,and the harmonics generated by the nonlinear propagation of the wave through the tissue,can be reduced by 15-30 dB.Compared with the short pulse,the reversal phase-inversion pulse can improve the contrast and definition of the harmonic image significantly. 展开更多
关键词 reversal pulse phase inversion Church model ultrasound imaging CONTRAST
下载PDF
车辆前照灯光轴校正装置
7
作者 李英 《邢台职业技术学院学报》 1998年第1期51-52,共2页
现代汽车上多装有汽车前照灯光轴校正装置,为便于操作和维修,本文主要介绍该装置组成及工作过程,以供参考。
关键词 前照灯 校正装置 光轴 固定组件 轴载荷 校正器 感器 线 调整螺钉 工作原理
下载PDF
Inverse Eigenvalue Problems for a Structure with Linear Parameters
8
作者 伍良生 杨家华 +3 位作者 魏源迁 门浩 杨庆坤 刘振宇 《Journal of Donghua University(English Edition)》 EI CAS 2005年第1期116-119,共4页
The inverse design method of a dynamic system with linear parameters has been studied. For some specified eigenvalues and eigenvectors, the design parameter vector which is often composed of whole or part of coefficie... The inverse design method of a dynamic system with linear parameters has been studied. For some specified eigenvalues and eigenvectors, the design parameter vector which is often composed of whole or part of coefficients of spring and mass of the system can be obtained and the rigidity and mass matrices of an initially designed structure can be reconstructed through solving linear algebra equations. By using implicit function theorem, the conditions of existence and uniqueness of the solution are also deduced. The theory and method can be used for inverse vibration design of complex structure system. 展开更多
关键词 inverse eigenvalue problems REDESIGN structure.
下载PDF
“Liverscore”is predictive of both liver fi brosis and activity in chronic hepatitis C
9
作者 Shoukat Ali Arain Qamar Jamal Amir Omair 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第41期4607-4613,共7页
AIM:To formulate a noninvasive index predictive of se-verity of liver f ibrosis and activity in chronic hepatitis C.METHODS:This cross sectional study was conducted on polymerase chain reaction positive,treatment nave... AIM:To formulate a noninvasive index predictive of se-verity of liver f ibrosis and activity in chronic hepatitis C.METHODS:This cross sectional study was conducted on polymerase chain reaction positive,treatment nave patients.Fibrosis was staged on a f ive point scale from F0-F4 and activity was graded on a four point scale from A0-A3,according to the METAVIR system.Patients were divided into two overall severity groups,minimal disease(< F2 and < A2)and signif icant disease(≥ F2 or ≥ A2).Eleven markers were measured in blood.Sta-tistically,the primary outcome variable was identif ica-tion of minimal and signif icant overall disease.Indices were formulated using β regression values of different combinations of nine statistically significant factors.Diagnostic performance of these indices was assessed through receiver-operating characteristic curve analysis.RESULTS:A total of 98 patients were included and of these 46 had an overall clinically significant disease.Our f inal six marker index,Liverscore for Hepatitis C,consisted of age,alanine transaminase,gamma-gluta-myl transpeptidase,apolipoprotein A-1,alpha-2 macro-globulin and hyaluronic acid.The area under the curve was found to be 0.813.On a 0-1 scale,negative predic-tive value at a cutoff level of ≤ 0.40 was 83%,while positive predictive value at ≥ 0.80 remained 89%.Al-together,61% of the patients had these discriminative scores.CONCLUSION:This index is discriminative of minimal and significant overall liver disease in a majority of chronic hepatitis C patients and can help in clinical de-cision making. 展开更多
关键词 Chronic hepatitis C Staging and grading Liver fibrosis and activity Noninvasive assessment Liverscore
下载PDF
Sound speed profile inversion using a horizontal line array in shallow water 被引量:4
10
作者 LI ZhengLin HE Li +3 位作者 ZHANG RenHe LI FengHua YU YanXin LIN Peng 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第1期47-53,共7页
It is better to use a simple configuration to enhance the matched-field inversion method based on a horizontal line applicability of ocean environment inversion in shallow water. A array (HLA) is used to retrieve th... It is better to use a simple configuration to enhance the matched-field inversion method based on a horizontal line applicability of ocean environment inversion in shallow water. A array (HLA) is used to retrieve the variation of sound speed profile. The performance of the inversion method is verified in the South China Sea in June, 2010. An HLA laid at bottom was used to receive signals from a bottom-mounted transducer. Inverted mean sound speed profiles from 9-hour long acoustic signals are in good agreement with measurements from two temperature chains at the sites of the source and receiver. The results show that an HLA can be used to monitor the variability of shallow-water sound speed profile. 展开更多
关键词 acoustic inversion matched-field processing horizontal line array
原文传递
(1.2)INVERSES OF OPERATORS BETWEEN BANACH SPACES AND LOCAL CONJUGACY THEOREM 被引量:27
11
作者 MA JIPU(Department of Mathematics,Nanjing University,Nanjing 210093,China) 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1999年第1期57-62,共6页
Let E and F be Banach spaces and f non-linear C1 map from E into F. The main result isTheorem 2.2, in which a connection between local conjugacy problem of f at x0E and a localfine property of f'(x) at x0(see the ... Let E and F be Banach spaces and f non-linear C1 map from E into F. The main result isTheorem 2.2, in which a connection between local conjugacy problem of f at x0E and a localfine property of f'(x) at x0(see the Definition 1.1 in this paper) are obtained. This theoremincludes as special cases the two known theorems: the finite rank theorem and Berger's Theoremfor non-linear Fredholm operators. Moreover, the thcorem gives rise the further results for somenon-linear semi-Fredholm maps and for all non-linear semi-Wedholm maps when E and F areHilbert spaces. Thus Theorem 2.2 not only just unifies the above known theorems but alsoreally generalizes them. 展开更多
关键词 Nonlinear semi-Fredholm maps Conjugacy problem Banach space
原文传递
Curcumin induces apoptosis through the mitochondria-mediated apoptotic pathway in HT-29 cells 被引量:12
12
作者 Jin-bo WANG Li-li QI +1 位作者 Shui-di ZHENG Tian-xing WU 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2009年第2期93-102,共10页
Objective: To investigate the effects of curcumin on release of cytochrome c and expressions of Bcl-2, Bax, Bad, Bcl-xL, caspase-3, poly ADP-ribose polymerase (PARP), and survivin of HT-29 cells. Methods: HT-29 ce... Objective: To investigate the effects of curcumin on release of cytochrome c and expressions of Bcl-2, Bax, Bad, Bcl-xL, caspase-3, poly ADP-ribose polymerase (PARP), and survivin of HT-29 cells. Methods: HT-29 cells were treated with curcumin (0-80 μmol/L) for 24 h. The release of cytochrome c from the mitochondria and the apoptosis-related proteins Bax, Bcl-2, Bcl-xL, Bad, caspase-3, PARP, and survivin were determined by Western blot analysis and their mRNA expressions by reverse transcriptase-polymerase chain reaction (RT-PCR). Results: Curcumin significantly induced the growth inhibition and apoptosis of HT-29 cells. A decrease in expressions of Bcl-2, Bcl-xL and survivin was observed after exposure to 10-80 μmol/L curcumin, while the levels of Bax and Bad increased in the curcumin-treated cells. Curcumin also induced the release of cyto- chrome c, the activation ofcaspase-3, and the cleavage of PARP in a dose-dependent manner. Conclusion: These data suggest that curcumin induced the HT-29 cell apoptosis possibly via the mitoehondria-mediated pathway. 展开更多
关键词 CURCUMIN APOPTOSIS Mitochondrial pathway HT-29 cells
原文传递
Science Letters:Optimization of soybean (Glycine max (L.) Merrill) in planta ovary transformation using a linear minimal gus gene cassette 被引量:3
13
作者 Ming LIU Jun YANG +1 位作者 Yun-qing CHENG Li-jia AN 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2009年第12期870-876,共7页
Soybean transformation by ovary-drip was improved by optimizing the length of the transformation pathway by cutting the styles. These modifications facilitated soybean transformation manipulation and improved transfor... Soybean transformation by ovary-drip was improved by optimizing the length of the transformation pathway by cutting the styles. These modifications facilitated soybean transformation manipulation and improved transformation reproducibility and efficiency. Using a linear minimal gus gene cassette as the foreign DNA, a maximum transformation frequency of 11% was obtained in flowers of the soybean cultivar ‘Liaodou 14’ with their styles mostly removed, whereas removal of only the stigma, partial style cutting and partial ovary cutting gave transformation frequencies of 0%, 1%, and 2%, respectively. An average transformation frequency of 8.2% was obtained when 619 flowers from three soybean cultivars (‘Liaodou 14’, ‘Liaodou 13’, and ‘Tiefeng 29’) were transformed by this optimized method. Southern blotting analysis showed that the gus reporter gene (encoding β-glucuronidase) was stably inherited with a simple pattern. Reverse transcription-polymerase chain reaction (RT-PCR) and GUS staining confirmed the expression of the gus gene in transgenic plants. 展开更多
关键词 SOYBEAN Glycine max (L.) Merrill In planta ovary-drip transformation Optimization Style cutting Minimal gus renorter gene cassette
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部