河西地区1960年至2008年潜在蒸发量的时空变化分析   总被引：6，自引：2，他引：4  

王亚敏  张勃  戴声佩  王海军  郭铃霞  康淑媛 《资源科学》2010,32(1):139-148

利用FAO Penman-Monteith模型计算出潜在蒸发量,运用数理统计理论和GIS空间分析技术,对河西地区潜在蒸发的时空特征进行了分析,结合Morlet小波分析和Hurst指数预测潜在蒸发变化趋势。结果表明:①河西地区潜在蒸发总体呈波动下降趋势,20世纪60年代～90年代,潜在蒸发为稳定下降期,约2.76mm/年,其中70年代减少率最大,约11.3mm/年;夏季潜在蒸发变化速率最大,约-2.07mm/年,其次为春季和秋季,冬季最小;②河西地区潜在蒸发自西北向东南呈递减趋势,靠近祁连山地区最小;潜在蒸发主要集中在春季和夏季,分别占年潜在蒸发30%和40%,秋季次之,冬季最小;③影响河西地区潜在蒸发的主要因素为风速,而影响春季潜在蒸发的主要因素是气温;④河西地区潜在蒸发存在12年左右的主振荡周期,年潜在蒸发表现出比较强的持续性,即未来趋势与近12年变化趋势的一致,潜在蒸发呈上升趋势。  相似文献   

Nonlinear dynamic analysis of the whole vehicle on bumpy road     

王威  李瑰贤  宋玉玲 《天津大学学报(英文版)》2010,16(1):50-55

Through the research into the characteristics of 7-DoF high dimensional nonlinear dynamics of a vehicle on bumpy road, the periodic movement and chaotic behavior of the vehicle were found.The methods of nonlinear frequency response analysis, global bifurcation, frequency chart and Poincaré maps were used simultaneously to derive strange super chaotic attractor.According to Lyapunov exponents calculated by Gram-Schmidt method, the unstable region was compartmentalized and the super chaotic characteristic of the nonlinear system was verified.Numerical results by 4-order Runge-Kutta method presented the multiform dynamic behavior of the system.  相似文献   

Hilbert-type integral inequality with the homogeneous kernel of 0-degree     

杨必成 《上海大学学报(英文版)》2010,14(6):391-395

Through using weight function, we give a new Hilbert-type integral inequality with two independent parameters and two pair of conjugate exponents, which is a best extension of a Hilbert-type integral inequality with the homogeneous kernel of 0-degree. The equivalent form, the reverses and some particular results are considered.  相似文献   

Hilbert-type integral inequality with the homogeneous kernel of O-degree     

YANG Bi-cheng 《上海大学学报(英文版)》2010,14(6)

Through using the way of weight function, we give a new Hilbert-type integral inequality with two independent parameters and two pair of conjugate exponents, which is a best extension of a Hilbert-type integral inequality with the homogeneous kernel of O-degree. The equivalent form, the reverses and some particular results are considered.  相似文献   

Does local dynamic stability of kayak paddling technique affect the sports performance? A pilot study     

Daniel Hamacher  Tobias Krebs  Guido Meyer  Astrid Zech 《European Journal of Sport Science》2018,18(4):491-496

During competition, kayak athletes must optimally adapt to environmental factors (e.g. wind, waves) to achieve peak performance. However, the ability to adapt to such perturbations has never been assessed in kayak paddling. Therefore, the aim of the current study was to evaluate the local dynamic stability in sports technique of youth sprint kayak athletes. In a cross-sectional study, 14 healthy male athletes were recruited from an elite youth sprint kayak squad. During an incremental kayak ergometer test, mean power, heart rates and local dynamic technique stability of hands, arms, trunk and paddle were registered and the association with the athletes 2000?m free-water times were estimated using mixed models. The 2000?m free-water performance significantly predicted the paddles (p?=?.037) local dynamic stability whereas no association was found for the trunk or the upper extremity kinematics. In conclusion, kayak athletes with high-performance capability over 2000?m paddling depict high local dynamic technique stability. This emphasizes the importance of a stable technique for advanced kayak skills, especially regarding paddling movements.  相似文献   

带Hardy-Sobolev临界指数和权函数的半线性椭圆问题的非平凡解     

窦井波 《中国科学院大学学报》2010,27(3):306-313

借助环绕定理和非线性分析技巧,研究如下一类带Hardy-Sobolev临界指数和权函数的半线性椭圆方程 - Δ u-μ u |x|² =λu+K(x) |u|^2*(s)-2u |x|^s , x∈Ω; u=0, x∈Ω, 解的存在性,其中Ω是 R ^<em>N具有光滑边界的有界开区域,0∈Ω,N≥5,0≤s≤2, 0≤μ≤ N-2 2 ², λ>０,K(x)是 上有界正函数.  相似文献   

指数函数模型线性化后的误差问题     

孙翠先  郑书清  王成 《唐山学院学报》2009,22(6):10-10,17

基于一元线性回归,对指数函数模型线性化后的随机误差存在的问题进行分析。引入对数正态分布,比较线性化前后误差的期望。  相似文献   

基于竞争力择优的产业联盟知识转移网络动态演化模型     

张宇洁  吴洁  刘亭亭 《科技管理研究》2013,33(11)

针对BA网络模型模拟现实世界的局限性,综合考虑产业联盟复杂网络的动态演化特性、竞争性等特点,构建了竞争力择优动态演化模型.该模型在考虑节点增加的同时,包含了节点的删除、旧节点之间竞争力择优的再生连接和反择优的删除连接.运用连续介质理论和平均场理论建立起与之对应的演化方程,导出该模型的度分布仍然具有无标度网络的一般性质,BA无标度网络是它的一种特殊情形.数值仿真的模拟结果验证了理论分析的正确性.研究结果表明,通过调节参数可以与现实中许多复杂网络的幂率指数相吻合,因此,改进的模型更具有适应性和真实性.  相似文献   

星型网络中的混沌同步     

樊庆端  刘曾荣 《上海大学学报(英文版)》2004,8(2):124-127

Using an example,it was analytically proved that the dynamical systems constructed on a star coupled network is more easy to be synchronized than that in coupled map lattices(CML).The result shows that the synchronization in small-world networks may be realized more easily.  相似文献   

关于朗道相变理论的一个修正     

田国瑞 《新乡师范高等专科学校学报》2007,21(2):23-24

由单轴铁磁体对自发磁化强度M的对称性,对朗道相变理论中自由能的表达式作了一个修正,并运用卡尔丹公式得到其临界指数β=1/3,与实验值一致。  相似文献