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Travelling Wave Solution of the Fisher-Kolmogorov Equation with Non-Linear Diffusion

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Applied Mathematics 2013年第8期4卷 148-160页

作者： Muhammad Shakeel Department of Mathematics Air University Islamabad Pakistan

In this paper we study one-dimensional Fisher-Kolmogorov equation with density dependent non-linear diffusion. We choose the diffusion as a function of cell density such that it is high in highly cell populated areas and it is small in the regions of fewer cells. The Fisher equation with non-linear diffusion is known as modified Fisher equation. We study the travelling wave solution of modified Fisher equation and find the approximation of minimum wave speed analytically, by using the eigenvalues of the stationary states, and numerically by using COMSOL (a commercial finite element solver). The results reveal that the minimum wave speed depends on the parameter values involved in the model. We observe that when diffusion is moderately non-linear, the eigenvalue method correctly predicts the minimum wave speed in our numerical calculations, but when diffusion is strongly non-linear the eigenvalues method gives the wrong answer.

关键词： Fisher-Kolmogorov Equation Non-Linear Diffusion Travelling Wave Wave Speed Pulled front Pushed front

Motion Characteristics of Single Electrons of Atoms of Atomic Gas of Hydrogen and Single Electrons of Hydrogen-Like Ions in Form Gas or Vapour during Decays of Such Atoms and Ions. Emission Line Spectra

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Journal of Modern Physics 2014年第14期5卷 1302-1320页

作者： Ivan Antonovych Strilets Kyiv Ukraine

For the first time the vector differential equation of central motion of single electron in electric field of an atomic nucleus as in external central electric field is set up and solved. Here the following findings are reported. Each of single electrons of a part of atoms of atomic gas of hydrogen and a part of hydrogen-like ions in the form of a gas or a vapour revolves around corresponding atomic nucleus in a flat spiral which has an interior maximum of turns density. The distance between each of these single electrons and corresponding atomic nucleus increases while a speed of single electron decreases. Such motion of single electrons takes place with no expenditures of external energy and points to decays of foregoing parts of atoms and ions. The electric field strength of the atomic nuclei of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour is inversely proportional to the distance between the atomic nucleus and the corresponding single electron by greater than the power of 3. Calculated cyclic frequency (rough value 3.5×1014 s-1) of revolution of the electron around the nucleus of atom of atomic gas of hydrogen (in interior maximum of turns density of the flat spiral), which moves at speed 2.2×106 ms-1, and central cyclic frequency of α-line of Balmer series (4.5×1014 s-1) have the same order of magnitude. This fact and line structure of experimental emission line spectra confirm the formation of all lines of these spectra by continuous slight emission of light front by single electrons. The formation of series of lines of emission line spectra is linked to repeated creations of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour.

关键词： Atomic Gas of Hydrogen Hydrogen-Like Ions Slight Emission of Light front by Single Electron Emission Line Spectra

Evaluate Tectonic Activity of Tehran City (Iran) Based on Geomorphic Indices, Field Investigation and Remote Sensing Study

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Open Journal of Earthquake Research 2019年第1期8卷 19-36页

作者： Z. Mohammadi Asl M. R. Abbassi Department of Geophysics Graduate School of Science Kyoto University Kyoto Japan International Institute of Earthquake Engineering and Seismology Tehran Iran

Active tectonics in the south part of Alborz Mountain (Iran) has greatly influenced the drainage system and geomorphic expressions. The metropolis of Tehran is located at the southern foothills of the Alborz Mountains at the abrupt topographic boundary between the mountain range and the northern border of the central Kavir Desert. The presence of active faults and tectonic activity, threatens the area and shows the vulnerability of this Tehran city. So the evaluation of active tectonics of Tehran City is necessary because of vast human activity, which has hidden geomorphic feature. Active tectonics of Tehran City was evaluated by using Digital elevation model (DEM) derived drainage network and three geomorphic indices basin (asymmetry factor (AF), basin shape index (Bs) and mountain front sinuosity (Smf)). The average of the three measured geomorphic indices was used to evaluate the distribution of relative tectonic activity in the study area. Furthermore to overcome some inevitable error in this method, field investigation was carried out also remote sense was studied, and finally the obtained results were compared with existing seismic data. The result confirms that the East South, East North and West North Tehran have high rate of relative tectonic activity (RTA) respectively.

关键词： Alborz Mountain Geomorphic Indices Asymmetry Factor Basin Shape Index Mountain front Sinuosity

Invariance in the Seasonal Median Dates for Mono-Modal Monsoonal Rainfall Distribution over the Semi-Arid Ecotone of Sub-Saharan West Africa

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International Journal of Geosciences 2013年第6期4卷 1-7页

作者： Naraine Persaud Moustafa Elrashidi Xiaobo Zhou Xining Zhao Xiaoli Chen Department of Agricultural and Biosystems Engineering Iowa State University Ames USA Department of Crop and Soil Environmental Sciences Virginia Polytechnic Institute and State University Blacksburg USA Institute of Water Saving Agriculture in Arid Areas of China Northwest A&F University Yangling China Natural Resources Conservation Service Lincoln USA

Seasonal distribution of mono-modal, monsoonal rainfall across the semi-arid ecotone of sub-Saharan of West Africa is highly variable and unpredictable. The ever-present risk of drought and crop failure in this environment often results in food shortages that are met by emergency food aid. Humanitarian assistance planners would be better prepared for such interventions in a timely manner if they have reliable indicators that forewarn the impending failure of the rains. A good indicator would be a characteristic of the seasonal rainfall distribution that can be shown to be reasonably invariant over time and space. The objective of this study is to investigate whether such invariance existed for the seasonal median date (meaning the date when 50% of the seasonal total occurs). Such invariance is expected since the sun’s cyclic declination forces the advance and retreat of the Inter-tropical front over West Africa. We examined the statistical properties of the seasonal median date for 1349 station-years of rainfall records for 30 rainfall stations in Burkina Faso and Niger with coordinates ranging from 9.88° to 18.5° north latitude and -4.77° to 13.2° longitude. The results showed that the median date was quite narrowly distributed over years with rather weak dependence on geographical coordinates. It can therefore be used as a reasonable ex-ante indicator of the success or failure of the rains as the rainy season progress.

关键词： Inter-Tropical front Inter-Tropical Convergence Zone Semi-Arid Rainfall Prediction Humanitarian Food Assistance Food Insecurity Semi-Arid Tropics Niger Burkina Faso

Research on the Effect of High Power Microwave on Low Noise Amplifier and Limiter Based on the Injection Method

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Journal of Electromagnetic Analysis and Applications 2010年第2期2卷 111-115页

作者： D. Chen L.M. Xu B.S. Zhang H.G. Ma 不详

The reliability of electronic device is threatened in high power microwave (HPM) environment. In accordance with the situation that the emulation is ineffective in evaluating the accuracy and precision of the HPM effect to electronic device, the experimental method is used to resolve the problem. Low Noise Amplifier (LNA) and Limiter are selected as the objects for the experiments, the structural characteristic of the front-end of radar receiver is described, the phenomena and criterion are elaborated and analyzed using injection method due to its ability to get an accurate threshold avoiding the complex coupling, the basic principle of injection experiment is demonstrated, and the method and process of effect experiment about Low Noise Amplifier and Limiter are also explained. The experimental system is established, and the system is composed of low power microwave source such as TWT, test equipment for obtaining the effect parameters, and some of auxiliary equipments as camera, optical microscope or electron microscopy, attenuator, detector, and directional coupler etc. The microwave delivered from source is adjusted to the power infused by attenuator, and pour in the decanting point of effecter via directional coupler, then the couple signal created by directional coupler is input to the recording instrument after detecting by detector, finally the power of effecter is obtained. The value of power, which damages the effecter in the microwave pulse environment, is classified at the index of sensitivity, and the threshold is obtained by power diagnose and wave test. Some regular understandings of the HPM effect to electronic device are obtained based on the results of the experiments. It turns out that the index of electronic device is influenced significantly by the energy via front door coupling, the MOSFET made up of GaAs is the most wearing part to HPM in LNA, the damage threshold of LNA is about 40dBm under single pulse while in repetitive pulse the value is from 33.3dBm to 43.9dBm according to different wa

关键词： High Power Microwave Low Noise Amplifier front Door Coupling Injection Experiment

Analysis on Extreme Gale of Capital Airport

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Meteorological and Environmental Research 2017年第4期8卷 12-14,19页

作者： Huang Jixiong Ji Pengfei Meteorological Center Air Traffic Management Bureau of North ChinaCAACBeijing 100621China

Observation data of extreme gale in Capital Airport during 1976-2013 were analyzed,and climate characteristics of extreme gale in Capital Airport were summarized. Moreover,three extreme gale weather processes with larger influences on December 10,2010,November 22,2011 and March 9,2013 were contrasted and analyzed,and results showed that extreme gale in Capital Airport mainly appeared during March-April or December-January. Occurrence frequency of extreme gale was the most from late afternoon to evening,and the minimum was from night to morning,while peak appeared during 14:00-15:00. Extreme gale of Capital Airport was dominated by northwest gale at the rear of cold front,and the peak occurred at the wind direction of 330°. The common effect of strong cold high pressure going south at the rear of ground cold front and highaltitude transverse trough turning vertical was main cause of extreme gale in Capital Airport,and momentum transmission below 500 hP a also had an important effect in the generation of extreme gale.

关键词： Extreme gale Cold front Northeast low pressure Momentum transmission Transverse trough turning vertical

The Roles Women Played During the Crusades

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英语广场（学术研究） 2019年第6期 8-9页

作者：李娇李永芹中国人民武装警察部队后勤学院基础部外语教研室

Medieval women participated in the European Crusades into the Middle East in various ways. Most commonly, they stayed home and took over responsibilities left by their husbands and fathers and brothers and sons who went on crusade. Some accompanied the crusading armies. This essay attempts to take an overall and concrete review of the roles of women during the Crusades.

关键词： the Crusades women on the home front women crusaders

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Pareto前沿在航线优化中的应用

控制工程 2005年第S2期12卷 60-64页

作者：樊铁成马孜大连海事大学自动化研究中心辽宁大连116026

在对水动力进行模拟仿真的基础上,提出了一种船舶航线最优化选择方案。在该方案中,多目标遗传算法被用来支持优化过程和最终决策来更好地解决这个系统中所存在的多目标、非线性的约束问题。以某公司某航线上的国际集装箱运输为例证明了... 详细信息

在对水动力进行模拟仿真的基础上,提出了一种船舶航线最优化选择方案。在该方案中,多目标遗传算法被用来支持优化过程和最终决策来更好地解决这个系统中所存在的多目标、非线性的约束问题。以某公司某航线上的国际集装箱运输为例证明了所提方案的有效性。其中航线上海洋的恶劣天气,尤其是海浪被作为一个主要因素考虑,把正常天气情况下的航线定义为主航线,而把恶劣天气情况下的航线看成是由以主航线上点为基点的连续弧线组成的轨迹。在建模的基础上,所提出的解决方案使该系统时间的延迟、油耗、加速度和砰击的可能性降到了最低。最后做了一个基于Paretofront的灵敏度分析,通过改变船舶装载量和释放约束,来检验这个方法的可靠性,发现此方法在实践中具有很高的可行性。

关键词：航线遗传算法优化 Pareto front 砰击

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出版社网页的设计与开发

科技与出版 2000年第5期 42-44页

作者：康军