Papers by Keyword: Fluctuation

Abstract: We analyzed fluctuations of interactions between low pressure reactive plasmas and nanoparticles formed in the plasmas, to shed light on origins of fluctuations of interactions and to control fluctuations in plasma processes. Spatiotemporal fluctuations of nanoparticle density develop not only in a linear way but also in a nonlinear way. The results suggest nonlinear interactions potentially induce spatial and temporal process fluctuations.

Abstract: We are developing plasma nanofabrication, namely, nanoand micro scale guided assembly using plasmas. We manipulate nanoand micro objects using electrostatic, electromagnetic, ion drag, neutral drag, and optical forces. The accuracy of positioning the objects depends on fluctuation of position and energy of a fine particle (= each object) in plasmas. Here we evaluate such fluctuations and discuss the mechanism behind them. In the first experiment, we grabbed a fine particle in plasma using an optical tweezers. The fine particle moves in a potential well made by the optical tweezers. This is a kind of Brownian motion and the position fluctuation can be caused by neutral molecule collisions, ion collisions, and fluctuation of electrostatic force. Among theses possible causes, fluctuation of electrostatic force may be main one. In the second experiment, we deduced interaction potential between two fine particles during their Coulomb collision. We found that there exist repulsive and attractive forces between them. The repulsive force is a screened Coulomb one, whereas the attractive force is likely a force due to a shadow effect, a non-collective attractive force. Moreover, we noted that there is a fluctuation of the potential, probably due to fluctuation of electrostatic force. These position and potential energy fluctuations may limit the accuracy of guided assembly using plasmas.

Abstract: Econophysics is a new interdiscipline where physics concept and methods are applied to financial analysis. For example, the application of theoretical physics in the modeling of financial markets has aroused wide concern. In the process of random fluctuation of prices in financial markets, many nonlinear dynamical problems are hidden in set coefficients and assumptions, resulting in the invisibility of market price fluctuations and unavailability of hidden benefits in fluctuations. Based on the analysis of price fluctuation mechanism in financial markets, this paper analyzes the characteristics of price fluctuation, and constructs the dynamical model of price fluctuation by means of physics theory, thereby providing a theoretical reference for the control and prevention of transaction risks.

Abstract: While analyzing the line loss, power supply enterprise always encounters circumstances in which the line loss rate swings heavily, especially during the months when there exists season alternate or long vacations, the fluctuation range of the line loss rate grows larger, and it will be apparently on the high side or on the low side. This text figured out the major factors influencing the fluctuation of the line loss rate, quantitatively analyzing three factors’ effects on line loss rate, which respectively are non-correspondence electric quantity for supplying and selling, the dedicated line which large consumer load transfers and the change of electric quantity which is nondestructive for sale, thus facilitating the grid enterprises dynamically analyzing the line loss in time, providing authentic line loss data for electric power departments at all levels, electricity board, power supply station, improving the accuracy of line loss analysis, dismissing the human factors during the fluctuation of line loss.

Abstract: Form accuracy and smooth surface is required in precision grinding. And the form accuracy and surface roughness are improved year by year. However, the more the surface roughness becomes smooth, the more the grinding marks become remarkable. The grinding mark deteriorates the uniformity of ground surface. In this study, relationship between the uniformity of non-axisymmetric aspherical ground surface and grinding condition is analyzed theoretically. As a result, it is found that there are optimum grinding conditions.

Abstract: Kinetic characteristics of chain drive system were investigated in this paper and some corresponding mathematical models were established. In accordance with the theory of chain drive, based on the multi-body dynamics software platform, a dynamic analysis model of timing bushing chain system for diesel engine was established. Chain tension force, chain contact force and chain fluctuation in a rotation cycle at different running speeds were analyzed. By analysis and evaluation these results, the kinematic and dynamic characteristics of the chain drive system during the operation could be effectively recognized, this research results can provide a basis for production tests.

Abstract: With the use of representative observed wind speed data for a whole year in Jiuquan field in Gansu province of Hexi Corridor ,we analysed the characteristics of ten-minutes wind speed, diurnal wind speed, monthly wind speed variation , as well as the influence of the wind power change rate in different time periods and diurnal variation in four seasons. Studies have shown that ten-minutes short-term wind turbulence characteristics was more obvious, with some randomness , but mainly exhibited typical diurnal characteristics of variation. In addition to mean state of wind conditions, there were sustained gale, short-term gale, continued small wind, regular small wind appeared. Monthly variation of wind speed is characterized by the "three peaks and three valleys" , showing the regular change that wind speed was larger in spring and summer , and it was smaller in autumn and winter. Daily fluctuation of wind electricity generation in four seasons presented similar trends, it was a peak-valley feature, valley generally appeared between 9-11 a.m., the peak occurred between 5-7 p.m..Wind power got larger between 1 and 11 p.m., this period was the peak electricity needed, wind power added can significantly ease the power grid pressure and will has significant positive effect for the power grid control. Ten-minute power variation was relatively stable, with the time interval increased, variation in electricity generation of one day rate increased gradually.

Abstract: With expansion of the scale of wind power used in grid, its impact on the power grid has become more and more apparent. Because of its characteristics of intermittency and randomness, it is necessary to study the effect of wind power fluctuation on power system risk. The large scale wind power farm is connected to the power grid, the influence of its output fluctuation on static security of power grids is studied in this paper, and corresponding evaluation risk index of the power grid security is built. A new type of power system analysis software (PSAT) is used for the simulation analysis, and the results show that output fluctuation of wind power has great influence on low voltage and overload risk of power system.

Abstract: To model the fluctuation characteristics of wind power is the basis for solving wind power integration problems. This paper studies the cluster effects of large-scale wind power, proposed a series of new cluster effect evaluation indexes, which have clear physical meanings and is conducive to the actual needs of the power system; based on Gaussian Mixture distribution, the probability distribution model of the cluster effect is established, which was verified with the actual operation data; The paper then proposed confidence interval model of cluster effect evaluation indexes, studied the variation of the cluster effect, shown the power function relationship between cluster effect evaluation indexes with scale of wind power.

Abstract: The model of metal solidification based on dissipative structure theory is established, which is reduced to threshold depending on the constitutional undercooling criterion, and trigger depending on volume fluctuation and temperature fluctuation. In accordance with the relation of volume fluctuation and temperature fluctuation, the transformation of solid-liquid interface is discussed in three cases.