旅游景区市场营销策略探微

在目前旅游景区市场环境的基础上,探讨旅游景区市场营销途径.指出网络营销、合作集团营销、零距离服务营销、绿色营销是当前旅游景区市场营销途径的主体.     

乌塘鳢Bostrichthys sinensis（Lacépède）的年龄研究

研究乌塘鳢年龄的鉴定材料采用胸鳍支鳍骨。结果表明：胸鳍支鳍骨上骨化环的数目与年轮数目相一致，体长频率分布与各年龄组体长分布曲线基本相符。用胸鳍支鳍骨的骨化环来鉴定乌塘鳢的年龄是可信的。     

银河系中球状星团的空间分布和运动轨道

选用银河系中29个累积光谱型为F型的球状星团样本。根据它们的视向速度，绝对自行等参数，归算处理后得出了各样本星团的空间分布和运动速度。并以此作为初始条件，在给定的3种银河系引力势模型中，采用数值积分方法计算出各样本星团的运动轨道。计算结果表明：（1）大部分样本星团都位于银心距5kpc-10kpc的范围内，相对于银心呈球对称分布，它们的速度也呈椭球分布；（2）29个样本星团按其金属度大小和基本性发类，可分属HB和MP两个次系，且样本星团数随金属度[Fe/H]而变化，在[Fe/H]＝－1．6处出现一个峰值；（3）所有样本星团的轨道运动都呈周期性，大都在一个有界而不封闭的周期轨道上运动，其最大银心距大都在40kpc以内。不同的引力势模型对球状星团轨道的具体形态影响不大，在给定的引力势模型下，当某些星团的运动轨道穿越距银心1kpc附近的区域时会出现“混沌”行为。而样本星团的金属度与其轨道形态之间的相关性并不明显；（4）29个样本星团的轨道半长轴、远银心距和方位周期随金属度的变化规律基本相似。轨道偏心率与金属度有关，对于所选的晕族样本星团而言，大约有24％的样本星团的轨道偏心率低于0．4，不同的引力势模型对近银心距、偏心率和参数的不确定度等量影响较小，但是对远银心距、径向周期和方位周期等参数影响较为明显。     

The composition of asteroid 2 Pallas and its relation to primitive meteorites

High resolution spectroscopic observations of asteroid 2 Pallas from 1.7-3.5 μm are reported. These data are combined with previous measurements from 0.4-1.7 μm to interpret Pallas' surface mineralogy. Evidence is found for low-Fe²⁺ hydrated silicates, opaque components, and low-Fe²⁺ anhydrous silicates. This assemblage is very similar to carbonaceous chondrite matrix material such as is found in type CI and CM meteorites, but it has been subjected to substantial aqueous alteration and there is a major extraneous anhydrous silicate component. This composition is compared to that of asteroid 1 Ceres. Although there are substantial differences in their broad band spectral reflectances, it appears that both asteroids are genetically related to known carbonaceous chondrites.     

Theoretical interpretation of the ground-based photometry of Saturn's B ring

New photographic photometry at small tilt angles during the 1979 and 1981 apparitions is combined with earlier data to yield several physical parameters for Saturn's B ring in red and blue colors. Phase curves are obtained for a mean tilt angle B ? 6°. The value of the volume density D is 0.020±0.004 with no indication of dependence on either the color or the tilt angle for 6°<B<26°. This conclusion is not altered significantly if the individual ring particles have a phase function similar to the phase curves of bright solar system objects. For the geometric albedo of a single particle we derive 0.61±0.04 (red) and 0.41±0.03 (blue), which are superior to earlier estimates because of the additional data now available. These values and the derived amount of multiple scattering as a function of tilt angle constrain the particle phase function in the red to be moderately backscattering. Inferred values of the particle single-scattering albedo are $\text{0.7≤}\text{ω}{}_0\text{(}\text{red}\text{) ≤0.92}$ and $\text{0.5≤}\text{ω}{}_0\text{(}\text{blue}\text{) ≤0.7}$, depending on the choice of phase function. No indication was found that the particle photometric properties might depend on the vertical distance from the central plane. Our results show that the ground-based photometry is entirely consistent with the classical, many-particle-thick ring model.     

The range of validity of the two-body approximation in models of terrestrial planet accumulation: I. Gravitational perturbations

Gravitational perturbations in semimajor axis, eccentricity, and inclination resulting from close planetesimal encounters (near 1 AU) out to 10 Tisserand sphere of influence radii were calculated by two- and three-dimensional numerical integration. These are compared with the results of treating the encounter as a two-body problem, as is customary in Monte Carlo calculations of orbital evolution and in numerical and analytical studies of planetary accumulation. It is found that for values of $\text{(}\text{V}\text{V}{}_{\mathrm{e}}\text{) ? 0.35 (V =}\text{relative velocity}\text{, V}{}_{\mathrm{e}}\text{=}\text{escape velocity of largest body}\text{)}$, the two-body body approximation fails to describe the outcome of individual encounters. In this low-velocity region, the two-body “gravitational focusing” cross section is no longer valid; “anomalous gravitational focusing” often leads to bodies on distant unperturbed trajectories becoming close encounters and vice versa. In spite of these differences, average perturbations given by the two-body approximation are valid within a factor of 2 when $\text{V}\text{V}{}_{\mathrm{e}}\text{> 0.07}$. In this same velocity range the “Arnold extrapolation,” whereby a few very close encounters are used to estimate the effect of many more distant encounters, is found to be a useful approximation.     

The Application of 3D Visible Technology to Reservoir Management

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General-altitude transformations between geocentric and geodetic coordinates

Formulas for the general-altitude (height above the ellipsoid) transformation from geocentric to geodetic coordinates and vice versa are derived. The set of four formulas is expressed in each of two useful forms: series expansions in powers of the Earth's flattening and series expansions in powers of the Earth's eccentricity. The error incurred in these expansions is of the order of one part in 3×10⁷.