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11.
Jagadish Singh Oni Leke 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This paper investigates the motion around the triangular equilibrium points, of a passively gravitating dust particle in the gravitational field of a low-mass post-AGB binary system, surrounded by circumbinary disc. The two bodies of the binary are modeled as a triaxial star and a radiating-oblate star. Due to small deviation of disc stars on circular orbits, we have assumed that the Coriolis and centrifugal forces of the stars are slightly perturbed. The triangular equilibrium points of the particle are found. These points are defined by, triaxiality of the primary star, oblateness and radiation of the secondary one and the gravitational potential from the disc mass. Further, when the disc mass increases, the particle moves nearer to the stars and farther away from the disc. In general, these equilibrium points are linearly stable when μ < μC; where μ is the mass ratio and μC is the critical mass function, defined by the parameters of the system. The effects of each of these parameters on the size of the stability region are stated, and the periodic motion around the stable points is examined. It is seen that the orbits are ellipses, and the orientation, eccentricities, lengths of the semi-major and semi-minor axes are influenced by the parameters of the problem. In particular, for our numerical linear stability analysis, we have taken an extremely depleted pulsating star, IRAS 11472-0800 as the post-AGB triaxial star, with a weakly-radiating young white dwarf star; G29-38 as the secondary. For this system, the stability result of the triangular points comes out different. Here, μC < μ throughout the entire range of the mass ratio and the critical mass function. Hence, the triangular equilibrium points are unstable. The stability of the orbits is tested using the Poincaré surfaces of section (Pss). The region of stability is controlled by the introduced parameters and the Jacobi constant. 相似文献
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R/S方法求解网络流量自相似参数的实现与应用 总被引:6,自引:0,他引:6
基于网络流量具有统计自相似性的理论,通过计算自相似参数Hurst值来检验流量的自相似程度。采用R/S方法对流量数据进行分析,给出了R/S方法详细的实现算法,通过实验的分析与比较,验证了自相似性的存在。自相似性是正常网络流量具备的特征,当流量发生异常时,Hurst值会出现明显的变化,本文将这一变化应用于DDoS攻击检测做了初步的探讨。基于自相似理论的网络流量异常检测技术与传统的基于统计异常技术和数据包特征匹配等方法相比,具有更高的准确性和可靠性。 相似文献
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为提高换热强度、解决设备内部高热流密度散热问题,采用实验方法研究R141b在不同直径(D=0.5mm和1.0mm)水平圆形微通道内的沸腾换热特性,分析了热流密度(q=2.0kW/m~2~47.6kW/m~2)、质量干度(x=0~0.6)、质量流速(G=111.11kg/(m~2·s)~333.33kg/(m~2·s))的变化对平均传热系数h的影响,探究不同情况下影响沸腾换热的主导因素。实验研究表明:平均传热系数h随热流密度q的增加而减小,在不同范围内减小速率有明显差异;热流密度q=2kW/m~2~5kW/m~2时质量流速G对平均传热系数h影响较明显,热流密度较高时质量流速G对换热影响很小;在质量流速G=111.11kg/(m~2·s)~333.33kg/(m~2·s),质量干度x0.3时,平均传热系数h随质量干度x增加而明显下降,在设计微通道换热器时应尽量使R141b处于初始沸腾阶段以获得更好换热效果,并采取一定措施预防干度过高引起的换热恶化。 相似文献
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R134a的热物理性质计算 总被引:1,自引:0,他引:1
氯氟碳化合物(CFC)作为制冷与空调设备的工质,长期以来被广泛应用于生产和生活的各个部门。近年来,人们逐步认识到某些CFC对臭氧层具有破坏作用和挥发后产生温室效应,因此不得不寻求新的替代工质。替代R12的制冷剂方案中,有单一工质,也有混合工质。在单一工质中,从长远意义上最有希望替代R12的新工质是民134a。为了对制冷系统应用R134a进行性能评价,而要一套完整的热物理性质公式。目前,有关R134a的热力学性质数据较多,但有关它的热物理性质数据却很少。本文列出并推导了R134a热物理性质的计算方程式,给出了部分计算数据,为用R134a作为制冷剂循环的制冷装置及换热器计算机辅助设计打下基础。 相似文献
16.
本文在介绍MB86R01的特点和功能的基础上,以飞机座舱显示系统中常见的姿态画面为例,设计并开发了基于MB86R01的图形显示平台.这种图形显示平台在未来飞机显示系统中具有广阔应用前景。 相似文献
17.
机载蒸发循环系统动态仿真 总被引:1,自引:0,他引:1
从部件的数学模型出发,根据闭环系统各部件的耦合关系,建立了机载蒸发循环系统的动态数学模型。对充注R142b的机载蒸发循环系统进行了动态仿真,仿真数据与试验数据基本吻合,仿真方法可靠,可以作为机载蒸发循环系统优化及系统控制的依据。 相似文献
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Dmitri Nikolaevich Severov Valentina Pshennikov Alexsandr Vasilievich Remeslo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Fronts and thermohaline structure of the Brazil–Malvinas Confluence System (BMCS) are studied from climatic data, “Marathon Exp. Leg.8, 1984” data, and Sea surface temperature (SST) data base “ds277-Reynolds” (1981–2000). The South Atlantic Central Water (SACW) is divided in two main types: tropical (TW) and subtropical water (ST). Water masses, Fronts, Inter-Frontal and Frontal Zones are analysed and classified: (a) the water masses: Tropical Low-Salinity Water, Tropical Surface Water, Tropical Tropospheric Water, Subtropical Low-Salinity Water, Subtropical Surface Water, Subtropical Tropospheric Water. T,S characteristics of intermediate, deep and bottom water defined by different authors are confirmed and completed; (b) the Inter-Frontal Zones: Tropical/Brazil Current Zone, Subtropical Zone and Subantarctic Zone; (c) the Frontal Zones: Subtropical, Subantarctic and Polar, and (d) the Fronts: Subtropical Front of the Brazil Current, Principal Subtropical Front, North Subtropical Front, Subtropical Surface Front, South Subtropical Front, Subantarctic Surface Front, Subantarctic Front and Polar Front. Several stable T–S relationships are found below the friction layer and at the Fronts. The maximum gradient of the oceanographic characteristics occurs at the Brazil Current Front, which can be any of the subtropical Fronts, depending on season. Minimum mean depth of the pycnocline coincides with the Fronts of the BMCS, indicating the paths of low-salinity shelf waters into the open ocean. In the work it is shown how to recover the horizontal and vertical thermohaline structure of waters from satellite data RSMAS SST. 相似文献