星际甲醇6.7GHz脉泽的激发机制

天文中醇脉泽源可分为两类．第一类脉泽源在6．7GHz及12．2GHz上有强的吸收特征，而第二类脉泽源则在6.7GHz和12.2GHz上有强的脉泽发射．注意到甲醇的第二类源总是6．7GHz和12．2GHz脉泽同时存在，并与超致密HII区成协，本文对此提出一种新的激发机制，即无粒子数反转的甲醇6．7GHz脉泽激发机制．本文论证了这一机制与天文条件相符，与其它机制工不排斥，互相补充，是一种有前途的模型．     

Probability of capture for the second fundamental model of resonance

The extension of the adiabatic invariant theory for one-degree of freedom Hamiltonian systems with varying parameters proposes a way of evaluating the probability of capture from one domain of the phase space into another. We derive here analytic expressions for these probabilities for a typical model of resonance of orderN. We show that the probabilities depend only upon two parameters and not four as expected a priori.     

Accuracy in measurements and the temperature and volume dependence of thermoelastic parameters

To obtain the temperatureT and volumeV (or pressureP) dependence of the Anderson-Grüneisen parameter _T , measurements with high sensitivity are required. We show two examples:P, V, T measurements of NaCl done with the piston cylinder and elasticity measurements of MgO using a resonance method. In both cases, the sensitivity of the measurements leads to results that provide information about _T (,T), where V/V ₀ andV ₀ is the volume at zero pressure. We demonstrate that determination of _T leads to understanding of the volume and temperature dependence ofq=( ln / lnV) _T over a broadV, T range, where is the Grüneisen ratio.     

风成沙纹形成的风洞模拟研究

风成沙纹形成于沙质床面下游的沙粒蠕移,发展于沙粒跃移－风沙流的“波粒二重性”作用,消亡于气流与风沙流的正弦波共振。以细沙和极细沙为优势粒级的天然沙丘沙是风成沙纹形成的最佳粒配。沙纹移动速度ＶＲ是缓慢的,其数量级为１０－１ｃｍ·ｍｉｎ－１～１０１ｃｍ·ｍｉｎ－１,实验关系式为：ＶＲ＝１．５８×（ＶＬ－５．５）０．６７。     

Magnetic resonance imaging of the Lake Agassiz–Lake Winnipeg transition

As part of the Geologic Survey of Canada (GSC) Lake Winnipeg Study, we have successfully imaged the Lake Agassiz to Lake Winnipeg transition in Section 4 of Core Namao 94-900-122a (i.e., from 313 cm to 465 cm), using a newly-developed magnetic resonance imaging (MRI) technique called SPRITE (Single-Point, Ramped Imaging with T₁ Enhancement). Whole core, gamma-ray attenuation measurements have been used to calculate the bulk porosity of the sediment at 1 cm intervals for comparison with the SPRITE images. Image contrast and image intensities observed in the SPRITE images of Section 4 are related to local porosity and magnetic susceptibility variations. In general, regions of the core with low signal intensity contain high porosity and low magnetic susceptibility. The best contrast between sediment layers is observed from regions of the core with high magnetic susceptibility. High signal intensity is observed from regions with low porosity and/or high magnetic susceptibility.     

An unsteady three-dimensional eutrophication model in Tolo harbour, Hong Kong

The eutrophication phenomenon often leads to undesirable water quality. This paper delineates an unsteady three-dimensional finite difference numerical model for eutrophication dynamics in the coastal waters of Tolo harbour, Hong Kong, employing the numerically generated, boundary-fitted, orthogonal curvilinear grid system as well as a grid “block” technique. It models the transport and interaction of nine water quality constituents. Adjustments of values of some kinetic coefficients in the model are effected through calibration with field data. It is demonstrated that the model can reasonably reproduce the interactions amongst all the water quality constituents, the eutrophication processes and, in particular, the featured bottom water anoxic condition during the summer in Tolo harbour.     

Phonon density of states in iron at high pressures and high temperatures

The phonon density of states (DOS) in iron has been measured in situ by nuclear resonance inelastic X-ray scattering (NRIXS) at high pressures and high temperatures in a resistively heated diamond anvil cell. The DOS data provide a variety of thermodynamic and elastic parameters essential for characterizing iron at depth in the Earth interior, such as average sound velocity, Debye temperature, atomic mean square displacement, average kinetic energy, vibrational entropy and specific heat. The NRIXS data were collected at 6, 20, and 29 GPa and at temperatures up to 920 K. Temperatures were directly determined from the measured spectra by the ratio of intensities of the phonon creation/annihilation side bands that are determined only by the Boltzmann factor. The change of the DOS caused by the structural transition from -Fe to -Fe is small and not resolvable within the experimental precision. However, the phonon energies in -Fe are clearly shifted to lower values with respect to - and -Fe. The temperature dependence of derived thermodynamic parameters is presented and compared with those obtained by Debyes model. The Debye temperatures that best describe the data decrease slightly with increasing temperature.     

大力开发整治射阳河之浅见

分析苏北里下河地区排水入海的最大干河－－射阳河在本流域中的地位和作用，目前河道淤积，工程老化和水污染严重等现状，以及射阳河蕴藏着的河海联运，水源充足，自然和人文景观众多潜在优势；阐述了整治和综合开发利用射阳河的重要性和迫切性；提出了整治和开发利用的３条总体原则，大体思路及保证顺利实施的关键措施。