oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 4 )

2019 ( 432 )

2018 ( 6252 )

2017 ( 6120 )

Custom range...

Search Results: 1 - 10 of 364972 matches for " 彭荣荣<br>WANG Guowei "
All listed articles are free for downloading (OA Articles)
Page 1 /364972
Display every page Item
基于色关联高斯噪声理论下捕食者-被捕食者模型中被捕食者的平均灭绝时间
The mean extinction time of prey for a preador-prey model based on the colored cross-correlated noises theory

王国威,付 燕,<br>WANG Guowei,FU Yan,PENG Rongrong
- , 2018,
Abstract: 在经典的捕食者—被捕食者模型中,引入分析猎物演化趋势的平均灭绝时间,利用最快下降法,通过理论计算推导得到该模型的平均首次通过时间的解析表达式,对噪声强度及其关联对被捕食者(猎物)和系统的平均灭绝时间之间的影响进行分析.理论计算结果的数值分析研究表明:(1)被捕食者的平均灭绝时间T+(x-→xu)随加性噪声强度D的变化趋势呈现出单调递减函数图像.(2)平均灭绝时间T-(x+→xu)随着D的增加而迅速减小,即T-(x+→xu)关于D呈现出单调减函数的关系图.(3)随着乘性噪声强度Q的增加,T(x±→xu)出现一个迅速增加并达到峰值的过程,然后迅速减小.(4)噪声间关联强度λ对平均灭绝时间T-(x+→xu)和T+(x-→xu)呈现出完全不同的影响方式.上述结果可以从统计物理学的角度为濒危物种、稀有珍贵物种保护提供一定理论指导,以确保生物多样性保护更有力地开展.
Adjustment and stabilization of sex ratio in Ceratosolen solmsi marchali
对叶榕传粉小蜂性比率的调节和稳定

PENG Yanqiong,YANG Darong,WANG Qiuyan,<br>艳琼,杨大,王秋艳
生态学报 , 2005,
Abstract: All fig-pollinating wasps share a similar life cycle. Generally some number of mated foundress wasps enter a receptive male fig, lay eggs in ovaries of flowers, then and die. The offspring finish development within the ovary. The wingless adult males first emerge from natal galls, and crawl around the interior of syconium, and mate with females still contained in galls. The mated female wasps then emerge from their galls, gather pollen, leave the syconium, and disperse to begin the cycle anew. The natural history of fig-pollinating wasps makes them well suited for the study of sex ratio evolution, especially local mate competition (LMC), and good fits have been obtained between empirical data and model preditions incorporating LMC and inbreeding effects at the population level. At present, LMC, inbreeding and haplodiploidy are generally regarded as three mechanisms of adjusting progeny sex ratio in fig wasps. Undoubtedly, the haplodiploid genetic system favors a female-biased sex ratio, and its effect is independent of any influence of LMC or inbreeding, a mother may adjust the sex ratio of her brood by fertilizing or not fertilizing eggs with sperm she stores in the spermatheca. However, LMC and inbreeding cannot explain all variation observed in sex ratios. In this study, we analyzed the impact on pollinator sex ratio of pollinator adjustment and non-pollinators. The results showed: (i) Sex ratio increases with reduced LMC intensities; (ii) The proportion of males drops with increasing foundress mating times, this being the first reported negative relationship between sex ratio and mating times; (iii) non-pollinating fig wasps did not affect the sex ratio of fig-pollinating wasps. Philotrypesis drained food resources from pollinators and starved them to death. Apocrypta bakeri parasitized pollinators or Philotrypesis and directly killed them. Though three species of non-pollinating fig wasps decreased pollinator numbers, no significant impact on pollinator sex ratio was found. Ensuring normal reproduction of fig-pollinating wasps might be a key factor that enables non-pollinating fig wasps to successfully invade the fig-pollinator mutualism system and coexist in the long term.
ITERATIVE APPROXIMATION PROBLEM OF FIXED POINTS FOR UNIFORMLY L-LIPSCHITZ AND ASYMPTOTICALLY PSEUDOCONTRACTIVE MAPPINGS
一致L-Lipschitz的渐近伪压缩映象不动点的Ishikawa迭代逼近问题

WANG Shaorong,WANG Pengde,YANG Zeheng,XIONG Ming,<br>王绍,,杨泽恒,熊明
系统科学与数学 , 2010,
Abstract: The purpose of this paper is to investigate the strong convergence of the modified Ishikawa and Mann iterative processes with errors for approximating fixed points of uniformly L-Lipschitz and asymptotically pseudocontractive mappings in an arbitrary real Banach space. By removing the restriction $$\sum\limits_{n=0}^{\infty}\alpha_{n}^{2}<\infty,\q \sum\limits_{n=0}^{\infty}\gamma_{n}<\infty, \q \sum\limits_{n=0}^{\infty}\alpha_{n}(\beta_{n}+\delta_{n})<\infty,\q \sum\limits_{n=0}^{\infty}\alpha_{n}(k_{n}-1)<\infty,$$it is proven that the relevant results remain true. The results presented in this paper improve and extend some recent existing results.
Cyclostationarity-based spectrum sensing in cognitive radio
认知无线电中基于循环平稳特征的频谱感知方法

QI Yuan,PENG Tao,QIAN Rong-rong,WANG Wen-bo,<br>漆渊,,,王文博
重庆邮电大学学报(自然科学版) , 2009,
Abstract: 提出一种基于信号频域循环平稳特征的频谱感知方法,该方法能够区分出授权和非授权信号的类型从而获取不同的频谱共享策略.将授权信号及非授权信号分别建模成线性周期时变变换,对授权信号和非授权信号进行频域的循环平稳特征分析,给出2类信号呈现循环平稳特征的位置,并给出用于鉴别2类信号的检测方法,其中推导了复过程中近似协方差矩阵的计算.仿真结果验证了该方法能在低信噪比中有效地鉴别出授权及非授权2类信号.
Numerical analysis of Marangoni convection in liquid bridge with liquid encapsulation
液封液桥内热毛细对流的数值模拟

Peng Lan,Li Yourong,Zeng Danling,Wang Zhong,<br>,李友,曾丹苓,王忠
力学学报 , 2006,
Abstract: The physical and mathematical models of the Marangoni convection in an encapsulated liquid column(or two immiscible coaxial liquid columlis)were established.A numerical simulation of the Marangoni convection in the encapsulated liquid column was performed by using the vorticity-streamfunction method and the alternative direction implicit scheme based on finite difference.The distributions of temperature and flow field in two immiscible coaxial liquid columns are obtained.It is verified that the liquid encapsulation can reduce the Marangoni convection in the encapsulated liquid bridge.Effects of non-dimensional parameters on Marangoni convection are analyzed.
Research on Two-Channels Pulse to Pulse Frequency Shifting Outdoor RCS Measurement Radar
双通道脉间变频外场RCS测试雷达的研究

Peng Gang,Tian Jin-jun,Wang Zhen-rong,<br>,田进军,王振
电子与信息学报 , 2006,
Abstract: Design of two-channels high-range-resolution pulse to pulse frequency shifting RCS outdoor measurement radar is researched. A waveform design and a system realization method are presented. The numerical relationship between range-profile’s distortion and frequency is analyzed. A method to calculate the target’s radial velocity by the measurement results is discussed based on the architecture that the radar can measure the target on two different frequency band at the same time. The target’s radial velocity effect on range profile can be corrected. The method is used to process the real outdoor measured data. The amplitude of the target’s imaging is boosted and the major lobe of the target’s imaging become narrower after being corrected.
Determination of Trace Levels of Nitrophenols in Water by Polyvinylpyrrolidone Modified Carbon Paste Electrode
聚乙烯毗咯烷酮修饰碳糊电极溶出伏安法测定水中硝基酚

Wang Kaixiong,<br>王凯雄,徐娟宝,,图治,王国顺
环境科学 , 1996,
Abstract: In this paper, a method to determine simultaneously p-ni-trophenol and 2,4-dinitrophenol in water by differential pulse voltammetry (DPV) with a carbon paste electrode modified with 10% (W/W) polyvinylpyrrolidone (PVPr) was described. The electrode showed a strong response to the nitrophenols, and the sensitivity and selectivity were much higher than ordinary carbon paste electrode. The nitrophenols were preconcentrated in 0.1 mg/L KCI solution during open circuit period, then the preconcentrated nitrophenols at the electrode were determined in phosphate buffer solution (pH7.0). The oxidation peak potentials were+0.88 V and+1.23 V (VS Ag-AgCl) respectively and two current peaks were completely separated. The detection limits were 0.50 ig/L (p-nitrophenol)and 1.80 ig/L (2,4-dinitrophenol). This method had been applied to the determination of nitrophenols in pol luted surface water,and the recoveries of p-nitrophenol and 2,4-dinitrophenol wer 90±6% and 86±5% respectively.
Study on the classification method of environmental risk for sudden accidents in drinking water sources
饮用水源地突发事故环境风险分级方法研究

MA Yue,PENG Jianfeng,SONG Yonghui,WANG Chunrong,<br>马越,剑峰,宋永会,王春
环境科学学报 , 2012,
Abstract: A methodological framework of identifying environmental risk sources and classifying environmental risks for drinking water sources was developed to reduce its environmental risk. Quantified potential consequences of accident and risk level were determined by mathematical models; while grading indices and risk factors were determined by the analytic hierarchy method and the indicator system method. The method system analyzed the intensity of environmental risk sources based on the quantity of dangerous chemicals and their physical-chemical characteristics. Environmental risk representation forms targeting on different receptors were investigated by using grading thresholds to illustrate the level of environmental risk for sudden accidents in drinking water sources. The classification method is composed of three steps, namely preliminary screening of environmental risk sources, risk assessment and risk classification. According to the developed method system, the environmental risk of sudden accidents in the drinking water source of one chemical industrial park in Nanjing was evaluated. The results showed that through screening and assessment, the level of environmental risk can be represented by the system modeling assessment; with the risk classification achieved in parallel. In this case, the environmental risk value was 6128.3. It is classified as a Grade I drinking water source, according to the grading matrix.
Effect of incorporating rice straw into the soil on rice growth, soil N and P nutrients under different N and P fertilization models
不同氮肥配施方法下稻草还田短期效应研究

PENG N,WANG Kai-Rong,WANG Kai-Feng,XIE Xiao-Li,<br>,王凯,王开峰,谢小立
中国生态农业学报 , 2007,
Abstract: To determine the effect of incorporating rice straw into the soil on rice growth,soil N and P nutrients under different N and P fertilization methods,a pot experiment was conducted where varying amounts of rice straw was incorporated into the soil under different N and P fertilization models.Results show that rice straw leads to short-term decrease in soil NH4-N concentration,increase in soil available P,and sluggished plant growth.Though the effect of rice straw under different N fertilization is the same,it is,however,stronger with increasing levels of rice straw application.Thus it can be stated in conclusion that though straw application has some positive effects,applications in large amounts can lead to Fe toxicity.After rice straw incorporation,good drainage and more N and P fertilization are needed to eliminate possible Fe toxicity induced by the incorporated rice straw.
Mill Vertical-Torsion Coupling Dynamic Vibration Analysis Based on Experimental Study
基于实验研究的轧机垂扭耦合振动分析

SHI Rong,ZHAO Jing,PENG Yan,LIU Bin,WANG Song-jun,LI Wei,<br>史,赵静,,刘斌,王松军,李伟
实验力学 , 2012,
Abstract: According to multiple-degree-of-freedom (MDOF) system vibration theory, a modeling method of vertical-torsion coupling dynamic model is proposed in this paper, and differential equations describing the vertical-torsion coupling dynamic vibration were established for the 1780 hot-rolling mill R1 of Cheng De Iron & Steel Group CO., LTD. Corresponding system coupling coefficients were confirmed based on the field test measured data. Then, mill inherent frequency of the vertical vibration, the torsion vibration and the vertical-torsion coupling vibration was calculated respectively and compared. According to the inherent frequency variation in vertical-torsion coupling vibration, the first 15-order inherent frequencies were achieved. Through dynamic response analysis for the vertical-torsion coupled system during steel biting excitation, maximum vibration amplitude of the vertical vibration and the torsion vibration for upper and lower roller system were calculated respectively. By comparing the vibration amplitudes, interaction of torsion vibration and vertical vibration was demonstrated, and the theoretical analysis results were verified by field testing.
Page 1 /364972
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.