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Multi-layer phenomena in petawatt laser-driven acceleration of heavy ions
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作者 苏琬晴 曹喜光 +2 位作者 马春旺 王玉廷 张国强 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第2期70-76,共7页
Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW l... Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum,ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process. 展开更多
关键词 petawatt laser-plasma interaction laser-driven heavy-ion accelerator for synthesizing superheavy nuclei PARTICLE-IN-CELL multi-layer phenomena target fabrication
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Unraveling Mystique: Long-Delay Echoes;Anomalous Propagation of Radar Signals under the Influence of Unidentified Anomalous Phenomena
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作者 John Tedesco Gerald Thomas Tedesco 《Open Journal of Applied Sciences》 2024年第12期3618-3648,共31页
This research study represents an ongoing research effort on Unidentified Anomalous Phenomena (UAP) with a focus on anomalous propagation of radar echo returns, mirroring established theoretical constructs of gravitat... This research study represents an ongoing research effort on Unidentified Anomalous Phenomena (UAP) with a focus on anomalous propagation of radar echo returns, mirroring established theoretical constructs of gravitational effects on light, which occur at higher frequencies and shorter wavelengths within the Electromagnetic Spectrum. These influences are also illustrated through other technologies, including Light Detection and Ranging (LIDAR) and the chromatic effects captured by hyperspectral cameras. This research addresses the complexities of interpreting unusual propagation patterns, such as Long Delay Echoes (LDE) and unexpected Field Echoes (UFE), which disrupt the anticipated propagation and echo protocols, thereby challenging our understanding and comprehension of radio transmission norms that may be influenced by a form of quantum entanglement. The paper posits a significant and largely unexamined correlation between these phenomena in the context of UAP activity, highlighting the urgent need for further research and innovative strategies in navigation technology and environmental monitoring to investigate these potential occurrences, which have remained enigmatic for nearly a century. Radar signals are vulnerable to intricate dynamics that can lead to Unusual Field Echoes (UFE), resulting in emergent anomalies, such as Multiple echo returns and LDEs. This study employed a 3-centimeter marine-based X-band radar operating in two scan geometries and a portable short-range millimeter-wave Doppler radar system. An analysis of these radar echoes over a two-year study identified signal propagation that deviated from navigational standards on Plan Position Indicators (PPI). This paper explores and investigates the potential impacts of UAP on radar transmission routes. Examining these complexities makes a case for an enhanced understanding of the interactions between established technological factors and elusive aerial phenomena. 展开更多
关键词 Radio Detection and Ranging (RADAR) Light Detection and Ranging (LIDAR) Long-Delay-Echo (LDE) Millimeter-Wave (MW) RADAR Unidentified Aerial phenomena (UAP) Anomalous Propagation (AP) Universal Field echoes (UFE) Plan Position Indicator (PPI)
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某丙烷脱氢装置大型管道高频振动特性分析
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作者 贺佳 梁浩华 +3 位作者 张国华 杨玉强 胡美妃 陈政清 《振动与冲击》 北大核心 2025年第4期144-150,共7页
大型石化管道服役期间,受复杂工作环境影响,可能发生高频剧烈振动,影响结构正常使用,并存在较大的安全隐患,因此,很有必要对此类振动现象开展相关研究。以某丙烷脱氢装置的大型管道为对象,基于现场实测数据,分析了管道振动特性,并利用... 大型石化管道服役期间,受复杂工作环境影响,可能发生高频剧烈振动,影响结构正常使用,并存在较大的安全隐患,因此,很有必要对此类振动现象开展相关研究。以某丙烷脱氢装置的大型管道为对象,基于现场实测数据,分析了管道振动特性,并利用传递矩阵法,获取了管道内部不同工况下的气柱固有频率。研究发现:管道振动的加速度幅值大、位移幅值小,振动频率较高,且卓越频率之间存在明显的倍数关系,即倍频现象,如26 Hz和52 Hz;气柱固有频率与管道固有频率接近,结合压缩机的激励频率,引发了管道的共振现象。该研究采用的方法简便高效,可用于分析丙烷脱氢装置大型管道的振动特性,探求管道振动的原因,并为类似管道的性能评估和减振方案设计提供参考依据。 展开更多
关键词 管道振动 倍频现象 气柱固有频率 传递矩阵法
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可压缩欧拉方程解的blowup现象 被引量:7
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作者 梁之磊 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2012年第4期657-659,共3页
考虑带有温度项的可压缩欧拉方程解的大时间行为.通过引入特殊的速度函数u(x,t)=c(t)x+b(t),其中b(t)可看作时间扰动项,得到一类显式光滑解.进而来研究欧拉方程解的blowup现象和整体存在性.
关键词 可压缩欧拉方程 blowup现象 光滑解
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一类退化抛物型方程初边值问题的Blowup 被引量:1
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作者 幸冬梅 《南昌大学学报(理科版)》 CAS 北大核心 2001年第4期326-329,共4页
利用Gauss公式和Poincare公式 ,讨论一类退化方程第一类初边值问题解u的爆破性质 ,并对 | u|进行估计。
关键词 退化抛物型方程 爆破性质 初值问题 边值问题 Causs公式 Poincare公式
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端齿同轴度误差对双锥度叶片-机匣系统加速特性分析
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作者 金淼 王艾伦 +3 位作者 王青山 尹伊君 陈雅孺 衡星 《振动工程学报》 北大核心 2025年第2期420-431,共12页
在航空涡轴发动机装配过程中,端齿同轴度误差是一个重要的技术指标,对整机系统的性能和使用寿命有重要的影响。以航空涡轴发动机涡轮叶片-机匣为研究对象,考虑将端齿同轴度误差(定位误差和定向角误差)引入到叶尖-机匣的间隙方程中,基于H... 在航空涡轴发动机装配过程中,端齿同轴度误差是一个重要的技术指标,对整机系统的性能和使用寿命有重要的影响。以航空涡轴发动机涡轮叶片-机匣为研究对象,考虑将端齿同轴度误差(定位误差和定向角误差)引入到叶尖-机匣的间隙方程中,基于Hamilton能量原理和Galerkin方法建立了考虑双锥度叶片-机匣系统的非线性动力学模型,通过ANSYS有限元方法验证了理论模型的正确性。在此基础上,运用Newmark-β数值求解方法分析了不同端齿同轴度误差对系统在定值加速函数(函数1)与余弦波加速函数(函数2)下的瞬态响应的影响,数值计算结果表明:增加同轴度误差,会进一步缩小叶尖与机匣之间的最小间隙,导致碰摩诱发的振幅更加严重;与函数1相比,采用函数2的加速度可以更快地通过系统临界转速,导致碰摩开始时间提前,当靠近目标转速时,减速作用可以有效减少最大碰摩力和侵入量,以减缓系统的隆起现象和跳跃现象。 展开更多
关键词 转子动力学 叶片-机匣碰摩 端齿同轴度误差 余弦波加速函数 跳跃和隆起现象
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一类四阶非线性波动方程初边值整体解的惟一存在性及其blowup性质
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作者 郭大鹏 《江汉大学学报(自然科学版)》 2005年第3期10-13,共4页
对在研究压缩物质层物理波的传播时所提出的一类四阶非线性波动方程进行了研究,用压缩映射原理和解的延拓方法证明了其初始值整体广义解和整体古典解的存在性与惟一性,同时还讨论了其解的爆破性质.
关键词 四阶非线性波动方程 初边值 整体解 blowup(爆破)性质
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Oral Fossilization Phenomena of Vocational College Non-English Majors
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作者 谢盈盈 《海外英语》 2011年第14期389-390,共2页
This thesis sets out to classify the fossilized errors made by the subjects from lexical and syntactic levels respectively,through the empirical experiment and questionnaire.
关键词 FOSSILIZATION phenomena Experiment LEXICAL SYNTACTIC
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阿秒条纹时间延迟及动量振荡振幅的研究
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作者 谢梦飞 姜维超 《光子学报》 北大核心 2025年第1期201-210,共10页
求解氦原子三维含时薛定谔方程,建立弱场近似经典解析模型,研究光电子中的阿秒条纹时间延迟和动量振荡振幅。发现阿秒条纹时间延迟和动量振荡振幅强烈依赖于极紫外脉冲的光子能量和红外脉冲的波长。阿秒条纹时间延迟对极紫外脉冲持续时... 求解氦原子三维含时薛定谔方程,建立弱场近似经典解析模型,研究光电子中的阿秒条纹时间延迟和动量振荡振幅。发现阿秒条纹时间延迟和动量振荡振幅强烈依赖于极紫外脉冲的光子能量和红外脉冲的波长。阿秒条纹时间延迟对极紫外脉冲持续时间不敏感,而动量振荡振幅随着极紫外脉冲持续时间的增加而减小。 展开更多
关键词 原子光学 强场激光物理学 红外 极紫外 光电离 超快现象
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尼泊尔工程地质条件分析
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作者 杨志刚 贾宁 乔建伟 《水利水电快报》 2025年第3期33-39,共7页
尼泊尔工程地质条件复杂,工程建设面临多种地质灾害威胁。通过收集文献,初步分析了尼泊尔的地质构造、地形地貌、地层岩性、水文地质条件和不良地质现象等工程地质条件。结果表明:①尼泊尔4条近东西向断裂可将其划分为5个构造单元;②尼... 尼泊尔工程地质条件复杂,工程建设面临多种地质灾害威胁。通过收集文献,初步分析了尼泊尔的地质构造、地形地貌、地层岩性、水文地质条件和不良地质现象等工程地质条件。结果表明:①尼泊尔4条近东西向断裂可将其划分为5个构造单元;②尼泊尔地形起伏大,可划分为8个不同的地貌单元;③发源于青藏高原的8条主要河流在纵向上将尼泊尔划分为六大流域;④对工程建设造成不利影响的不良地质现象主要包括地震、崩塌、滑坡和泥石流等,在工程建设初期应充分评价地震及“崩滑流”对建设场地的不利影响,重点项目建议开展专项研究。研究成果可为尼泊尔工程建设提供技术支撑。 展开更多
关键词 工程地质条件 工程建设 不良地质现象 尼泊尔
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CP^n(Q)的加权blowup及陈-阮上同调群 被引量:1
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作者 林奕武 《中山大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第2期1-4,10,共5页
对加权射影空间CPn(Q)进行了加权blowup,分析了blowup后的toric结构和orbifold结构,以及所有twisted sector的变化。用组合论的方法计算了blowup前后每个twisted sector的奇异上同调,并且分析了其陈-阮上同调群的变化。
关键词 加权射影空 加权blowup 陈-阮上同调群
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拟线性双曲方程的两种Blowup机制
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作者 季小东 郑琴 何春 《解放军理工大学学报(自然科学版)》 EI 2002年第5期99-102,共4页
对于一般的初值 ,拟线性双曲方程不一定存在整体经典解 ,若不存在整体经典解 ,则解在有限时间内 blowup。主要考虑几种特殊的 Burgers方程 ,讨论其经典解的存在区间以及解发生 blowup时 ,几何blowup与常微 blowup之间的先后顺序。
关键词 拟线性双曲方程 blowup机制 BURGERS方程 几何blowup 常微blowup 整体经典解
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Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries 被引量:12
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作者 Ao Xu Wei Shyy Tianshou Zhao 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2017年第3期555-574,共20页
Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electro... Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined. 展开更多
关键词 Lattice Boltzmann method Transport phenomena Multiphase flow Fuel cells Flow batteries
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Predictive factors for photic phenomena after refractive,rotationally asymmetric,multifocal intraocular lens implantation 被引量:16
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作者 Hungwon Tchah Kiyeun Nam Aeri Yoo 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2017年第2期241-245,共5页
AIM: To investigate the independent factors associated with photic phenomena in patients implanted with refractive,rotationally asymmetric,multifocal intraocular lenses(MIOLs).METHODS: Thirty-four eyes of 34 patie... AIM: To investigate the independent factors associated with photic phenomena in patients implanted with refractive,rotationally asymmetric,multifocal intraocular lenses(MIOLs).METHODS: Thirty-four eyes of 34 patients who underwent unilateral cataract surgery,followed by implantation of rotationally asymmetric MIOLs were included.Distance and near visual acuity outcomes,intraocular aberrations,preferred reading distances,preoperative and postoperative refractive errors,mesopic and photopic pupil diameters,and the mesopic and photopic kappa angles were assessed.Patients were also administered a satisfaction survey.Photic phenomena were graded by questionnaire.Independent-related factors were identified by correlation and bivariate logistic regression analyses.RESULTS: The distance from the photopic to the mesopic pupil center(pupil center shift) was significantly associated with glare/halo symptoms [odds ratio(OR)=2.065,95% confidence interval(CI)=0.916-4.679,P=0.006] and night vision problems(OR=1.832,95% CI=0.721-2.158,P=0.007).The preoperative photopic angle kappa was significantly associated with glare/halo symptoms(OR=2.155,95% CI=1.065-4.362,P=0.041).The photopic angle kappa was also significantly associated with glare/halo symptoms(OR=2.155,95% CI=1.065-4.362,P=0.041) and with night vision problems(OR=1.832,95% CI=0.721-2.158,P=0.007) in patients implanted with rotationally asymmetric MIOLs.CONCLUSION: A large pupil center shift and misalignment between the visual and pupillary axis(angle kappa)may play a role in the occurrence of photic phenomena after implantation of rotationally asymmetric MIOLs. 展开更多
关键词 rotationally asymmetric multifocal intraocular lens pupil center photic phenomena dysphotopsia kappa angle pupil center shift
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BLOWUP CRITERION FOR THE COMPRESSIBLE FLUID-PARTICLE INTERACTION MODEL IN 3D WITH VACUUM 被引量:3
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作者 丁时进 黄炳远 卢友波 《Acta Mathematica Scientia》 SCIE CSCD 2016年第4期1030-1048,共19页
In this article, we consider the blowup criterion for the local strong solution to the compressible fluid-particle interaction model in dimension three with vacuum. We establish a BKM type criterion for possible break... In this article, we consider the blowup criterion for the local strong solution to the compressible fluid-particle interaction model in dimension three with vacuum. We establish a BKM type criterion for possible breakdown of such solutions at critical time in terms of both the L^∞ (0, T; L^6)-norm of the density of particles and the ^L1(0, T; L^∞)-norm of the deformation tensor of velocity gradient. 展开更多
关键词 blowup criterion compressible fluid-particle interaction model VACUUM
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Gas–liquid mass transfer and flow phenomena in the Peirce–Smith converter: a water model study 被引量:5
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作者 Xing Zhao Hong-liang Zhao +1 位作者 Li-feng Zhang Li-qiang Yang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2018年第1期37-44,共8页
A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a... A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume (Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coeffi- cient), and gas utilization ratio (t/) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and n steadily increased. When the converter was rotated clockwise, both Ak/F and t/increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these para- meters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3.h-1 and 10°, respectively. 展开更多
关键词 Peirce-Smith converter water model mass transfer flow phenomena volumetric mass transfer coefficient
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ELASTIC MEMBRANE EQUATION WITH MEMORY TERM AND NONLINEAR BOUNDARY DAMPING:GLOBAL EXISTENCE,DECAY AND BLOWUP OF THE SOLUTION 被引量:2
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作者 Abderrahmane ZARA Nasser-eddine TATAR Salem ABDELMALEK 《Acta Mathematica Scientia》 SCIE CSCD 2013年第1期84-106,共23页
In this paper we consider the Elastic membrane equation:with memory term and nonlinear boundary damping: Under some appropriate assumptions on the relaxation function h and with certain initial data, the global exis... In this paper we consider the Elastic membrane equation:with memory term and nonlinear boundary damping: Under some appropriate assumptions on the relaxation function h and with certain initial data, the global existence of solutions :and a general decay for the energy are established using the multiplier technique. Also, 'we show that a nonlinear source of polynomial type is able to force solutions to blow up in finite time even in presence of a nonlinear damping. 展开更多
关键词 elastic membrane equation global existence boundary damping boundarysource general decay blowup
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SELF-SIMILAR SOLUTIONS AND BLOW-UP PHENOMENA FOR A TWO-COMPONENT SHALLOW WATER SYSTEM 被引量:2
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作者 周寿明 穆春来 王良晨 《Acta Mathematica Scientia》 SCIE CSCD 2013年第3期821-829,共9页
In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equat... In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation. 展开更多
关键词 Self-similar solutions blow-up phenomena two-component shallow water system
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Numerical simulation of flow phenomena and optimum operation of tundish 被引量:2
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作者 时章明 鄂加强 +3 位作者 刘春洋 梅炽 张全 周应其 《Journal of Central South University of Technology》 2003年第2期155-158,共4页
To enhance the quality of grade 20 carbon-steel on the continuous casting production line, the mechanism of forming blowholes and non-metallic inclusions in billets and numerical simulation of flow phenomena about liq... To enhance the quality of grade 20 carbon-steel on the continuous casting production line, the mechanism of forming blowholes and non-metallic inclusions in billets and numerical simulation of flow phenomena about liquid steel in tundish were studied. The results show that the configuration and operation of tundish play an important part in quality assurance of grade 20 carbon-steel products. By optimizing the configuration of the tundish, the depth of liquid bath in tundish is enhanced, the impact of liquid steel is decreased, and the residence time of liquid steel is lengthened, which is useful for eliminating inclusions and blowholes and improving the service life of tundish. Improving the pouring and tapping operation of liquid steel can avoid the contact of liquid steel with air, and decrease re-oxidation. Strict control of the superheat degree of casting liquid steel can decrease the non-metallic inclusion content of the re-oxidation in billets and reduce the erosion of tundish. The inclusions and blowholes in the continuous casting grade 20 steel billets are reduced to a great extent and qualification rate is enhanced from 60% to 80%. 展开更多
关键词 TUNDISH flow phenomena NUMERICAL simulation OPTIMUM
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The high-latitude ionospheric phenomena observed by DPS-4 at Zhongshan Station, Antarctica 被引量:3
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作者 刘顺林 刘瑞源 贺龙松 《Chinese Journal of Polar Science》 1999年第2期141-148,共8页
Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphc... Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphcric phcnomena occurred in the cusp region. They are particle precipitation effects in the E region. F region magnetic noon phenomena, slant Es phenomena and lacuna. F layer irregularity zone (FLIZ) phenomena, and auroral oval identification. Typical examples of ionograms and ionogram sequences observed at Zhongshan Station are displayed in this paper. 展开更多
关键词 IONOGRAM high-latitude ionosphere high-latitude phenomena Zhongshan Station
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