Nonlinearity of Nonradial Modes in Evolved Stars

We show that in evolved stars, even at relatively low surfaceamplitudes, nonradial modes become strongly nonlinear in thehydrogen shell source, where the Brunt-Väisälä frequency hasits absolute maximum. The measure of nonlinearity is the productof horizontal displacement times the radial wavenumber, . It becomes large already in evolved -Scuti stars.This nonlinearity presents a major problem for interpretations ofamplitude modulation in RR Lyrae stars in terms of nonradial modeexcitation.     

The Apsidal Antialignment of the HD 82943 System

We perform numerical simulations to explore the dynamical evolution of the HD 82943 planetary system. By simulating diverse planetary configurations, we find two mechanisms of stabilizing the system: the 2:1 mean motion resonance (MMR) between the two planets can act as the first mechanism for all stable orbits. The second mechanism is a dynamical antialignment of the apsidal lines of the orbiting planets, which implies that the difference of the periastron longitudes ₃ librates about 180° in the simulations. We also use a semi-analytical model to explain the numerical results for the system under study.     

A general model for modifying Stokes’ formula and its least-squares solution

Today the combination of Stokes formula and an Earth gravity model (EGM) for geoid determination is a standard procedure. However, the method of modifying Stokes formula varies from author to author, and numerous methods of modification exist. Most methods modify Stokes kernel, but the most widely applied method, the remove compute restore technique, removes the EGM from the gravity anomaly to attain a residual gravity anomaly under Stokes integral, and at least one known method modifies both Stokes kernel and the gravity anomaly. A general model for modifying Stokes formula is presented; it includes most of the well-known techniques of modification as special cases. By assuming that the error spectra of the gravity anomalies and the EGM are known, the optimum model of modification is derived based on the least-squares principle. This solution minimizes the expected mean square error (MSE) of all possible solutions of the general geoid model. A practical formula for estimating the MSE is also presented. The power of the optimum method is demonstrated in two special cases. AcknowledgementsThis paper was partly written whilst the author was a visiting scientist at The University of New South Wales, Sydney, Australia. He is indebted to Professor W. Kearsley and his colleagues, and their hospitality is acknowledged.     

Geographic Patterns of Air Passenger Transport in China 1980–1998: Imprints of Economic Growth,Regional Inequality,and Network Development*

This research analyzes the geographic patterns of domestic air passenger transport in China from 1980 to 1998, with three foci: (1) impacts of economic reforms, (2) regional inequality in air transport development, and (3) network development. Accessibility to air transport improved significantly as China expanded its air transport system, 1980–1998. The dominance of major airports declined as the air transport system expanded to medium and small cities. The centroid of passenger volume migrated toward southeast, consistent with the expansion of economic growth in southeast coastal areas. The rule of distance decay in air traffic was more applicable to China in 1998 than in 1985 as the market economy worked its way into China's air transport system. The East Region had a much higher share of air passengers than its share of population and GDP, followed by the West and the Middle Regions, reflecting an interesting “flyover” effect. By 1998, a hub‐and‐spoke air transport system was clearly in place in China.     

重力场中正高的理论与研究

在大地测量学中的正高又称海拔高，它为地球重力场所制约，海拔高在当今数字地球中占有重要位置，它的功用已表现在经济、国防建设科学研究等诸多方面。尽管近50年来我国仍采用正常高系统，但随着时代的发展、研究的深入，如今推求正高的精度又与正常高的非常接近，况且它又符合我国幅员广大的高海拔山区的实际情况，因此用正高（系统）代替正常高（系统）的观念将会被人们所接受。这里对正高研究与发展的3个阶段进行了阐述，它们是：正高的定义与近似值，正常高的提出，正高的精确值的推求；还对高程(正高)基准面(geoid)上w0（大地水准面上的位值）的推求方法加以介绍。     

Integral Equations for Kinematic Dynamo Models

A new technique for the treatment of the kinematic dynamo problem is presented. The method is applicable when the dynamo is surrounded by a medium of finite conductivity and is based on a reformulation of the induction equation and boundary conditions at infinity into an integral equation. We show that the integral operator involved here is compact in the case of homogeneous conductivity, which is important for both mathematical and numerical treatment. A lower bound for the norm of then yields a necessary condition for the generation of magnetic fields by kinematic dynamos. Numerical results are presented for some simple ²-dynamo models. The far-field asymptotics for stationary and time-dependent field modes are discussed.     

218P0 测量法寻找基岩裂隙水研究

论述了利用218P₀测量法寻找基岩裂隙水的基本原理;阐明了水、氡在断裂等构造条件下,运移、汇集、赋存的特征及富氡富水、氡少水贫和同步对应,及部位一致的基本规律。介绍了高值异常峰顶型、低值异常凹斗型、无异常平缓型三种曲线类型及其分析方法。试验实践证明,此法具有轻便快速、高效准确、省时省力等优点,辅以其它方法找水定井,成井率达到98.2%.实践意义大,推广价值高。     

Analysis of oil lens removal by extraction through a seepage face

Removal of LNAPL (oil) from an aquifer is described using a multiphase flow model. At the well boundary seepage face conditions are imposed. These conditions are implemented in a numerical model and withdrawal in a twodimensional domain is simulated for two different geometries of the oil lens and for varied values of the physical parameters. Assuming vertical equilibrium, the oil flow equation is reduced by vertical integration. The well boundary condition is approximated by imposing zero oil lens thickness. Similarity solutions of the reduced equations for the two geometries show good agreement with the numerical results in most cases.     

Obtaining the free frequencies of the non‐rigid Earth

In this paper, the mathematical algorithm elaborated by González, Getino and Farto (1998) is applied to four different nonrigid Earth models, in order to obtain the analytical expressions of the corresponding free frequencies. The solutions are studied, and the contributions of the different considered effects are evaluated. A numerical integration is also carried out, showing the validity of the obtained analytical solutions.