晴朗天气大气对微波的衰减

本文用两套公式，由标准大气的气象要素分别计算了０￣２ｋｍ、２￣６ｋｍ（不含２ｋｍ）、６￣１１ｋｍ（不含６ｋｍ）及０￣１１ｋｍ晴空大气层中氧分子、水汽分子和大气气体分子对微波的衰减。分析了各层大气吸收的特性。结果表明两套公式计算晴空大气衰减都是成熟的。     

Interaction of oblique waves with an infinite cylinder

A Green's function procedure is applied to compute the oblique wave interaction with a cylinder of arbitrary section on the free surface in water of infinite depth. Also, the hydrodynamic coefficients associated with the motion of the cylinder oscillating in its three degrees of freedom, periodic along its axis, are treated. A computer program based on the present procedure is found to be accurate and efficient. The results are applicable to the analysis of floating breakwaters, floating bridges, ship hulls and other elongated structures on a free surface.     

集中荷载作用下装配式迭合面板研究

本文通过集中荷载作用下钢筋砼装配式迭合面板的试验，研究了单向板抗弯计算荷载有效分布宽度和弯矩分配系数的主要影响因素。根据试验结果建立了单向板抗弯荷载有效分布宽度计算公式。计算结果和试验结果符合性较好，并提出了连续板弯矩分配系数。     

Influence of wave approach angle on TLP's response

The current study focuses on the response analysis of triangular tension leg platform (TLP) for different wave approach angles varying from 0° through 90° and its influence on the coupled dynamic response of triangular TLPs. Hydrodynamic loading is modeled using Stokes fifth-order nonlinear wave theory along with various other nonlinearities arising caused by change in tether tension and change in buoyancy caused by set down effect. Low frequency surge oscillations and high frequency tension oscillations of tethers are ignored in the analysis. Results show that wave approach angle influences the coupled dynamic response of triangular TLP in all degrees of freedom except heave. Response in roll and sway degrees of freedom are activated which otherwise are not present in TLP's response to unidirectional waves. Pitch and roll responses are highly stochastic in nature indicating high degree of randomness. Variation in surge, sway and heave responses are nonlinear and are not proportional to change in wave height for the same period.     

Ambiguous reflection coefficients for anelastic media

The calculation of reflection and transmission coefficients of plane waves at a plane interface between two homogeneous anelastic media may become ambiguous because it is not always obvious how to determine the sign of the vertical component of the slowness vector of the scattered waves. For elastic media, the sign is determined by applying so-called radiation condition when the slowness vector is complex-valued, but it has long been known that this approach does not work satisfactorily for anelastic media. Other approaches have been suggested, e.g., by requiring that the reflection and transmission coefficients should vary continuously with increasing incident angles, or by relating the sign to the direction of the energy flux. In the present paper, it is shown that these approaches may give different results, and that the results can be inconsistent with the elastic case even for weak attenuation. Instead, it is demonstrated that the ambiguity in the reflection coefficient can be resolved by expressing the seismic response of a point source over an interface as a superposition of plane waves and their reflection coefficients, and solving the resulting integral by the saddle point approximation. Although the saddle point itself (point of stationary phase) does not provide new insight, the ambiguity is removed by considering the steepest descent path through the point. Ray synthetic seismograms computed by this method compare well with synthetics computed by the reflectivity method, which does not suffer from the above-mentioned ambiguity since the integration path is taken along the real axis. This paper concentrates on the isotropic case, but it is discussed how the result may be extended to layered transversely isotropic media. The suggested approach, derived for a point source and plane layers, does not directly apply to 2-D or 3-D laterally inhomogeneous media, or to media of general anisotropy. A generalization of the result found is that the sign of the vertical slowness components should be chosen according to the energy flux direction for subcritical incidence and according to the radiation condition for supercritical incidence, even if this creates a discontinuity in the coefficients at the critical incidence angle. Such a discontinuity is sometimes necessary to get results which are consistent with the elastic case. It is discussed how the generalized result can be obtained by applying certain continuity criteria for the sub-and supercritical angle intervals, but the validity of this approach for general models remains to be proved.     

南海西南季风爆发前后海-气通量交换系 数研究

动量交换系数(CD)、感热交换系数(CH)和潜热(或水汽)交换系数(CE)是气候模式中参数化海-气通量必需的参数,不同地区、天气、海况的试验中计算结果各异。文章利用2002年4月24日至6月20日在西沙海区进行的第3次南海海-气通量观测试验资料,使用涡旋相关法和TOGA COARE2.5b版本通量计算方案,计算了西南季风爆发前后海-气界面动量、感热通量、潜热通量等的湍流交换系数,讨论了各通量交换系数的变化特征及其与气象要素变化的关系。结果表明:西南季风爆发前后,随着风向、风速、云量、降水、湿度及海面状态等变化,通量交换系数也发生变化:中性条件动量交换系数(CDn)在季风爆发前数值略小,季风爆发后数值增大;中性条件感热交换系数和潜热交换系数(CHn,CEn)对天气变化的反应不够敏感。动量交换系数主要受风速影响,但在不同风速区间相关关系有异。(CH)与海-气温差呈现正相关关系,和气温有明显的负相关关系。CE与风速的关系密切,但当风速>12 m/s,CE随风速的变化趋向一个稳定值。另外当海-气温差大约<2℃时,CE随着海-气温差增大相应增大,反映了通量交换系数不仅与风影响下的下垫面特性有关,而且还与稳定度参数有关。各通量交换系数与气象要素变化的关系可以拟合为多项式或者简单的线性关系式。     

P-SV波AVO方法研究进展

为有效地利用AVO(amplitude versus offset)信息来反演岩性参数和预测油气储层，详细介绍了P—SV转换波AVO方法的研究现状和主要进展，并针对几种具有代表性的方法的基本思路、方法特点及参数反演等方面进行了对比和评述。同时，给出了两个不同形式的近似公式，并讨论了利用这两种近似公式进行AVO分析的思路和参数反演的方法，通过对比和讨论可以得出：不同近似的主要目的是为了提高近似精度并体现不同的岩性参数对反射系数的影响、敏感程度及其在参数反演中的意义；根据弹性模量和波速之间的关系，目前所有的PP波和P—SV波反射系数近似公式都可以统一表示成射线参数幂级数的形式，这些结论对于AVO理论研究和参数反演都具有重要意义。     

An Improved Gradual Deformation Method for Reconciling Random and Gradient Searches in Stochastic Optimizations

Constraining stochastic models of reservoir properties such as porosity and permeability can be formulated as an optimization problem. While an optimization based on random search methods preserves the spatial variability of the stochastic model, it is prohibitively computer intensive. In contrast, gradient search methods may be very efficient but it does not preserve the spatial variability of the stochastic model. The gradual deformation method allows for modifying a reservoir model (i.e., realization of the stochastic model) from a small number of parameters while preserving its spatial variability. It can be considered as a first step towards the merger of random and gradient search methods. The gradual deformation method yields chains of reservoir models that can be investigated successively to identify an optimal reservoir model. The investigation of each chain is based on gradient computations, but the building of chains of reservoir models is random. In this paper, we propose an algorithm that further improves the efficiency of the gradual deformation method. Contrary to the previous gradual deformation method, we also use gradient information to build chains of reservoir models. The idea is to combine the initial reservoir model or the previously optimized reservoir model with a compound reservoir model. This compound model is a linear combination of a set of independent reservoir models. The combination coefficients are calculated so that the search direction from the initial model is as close as possible to the gradient search direction. This new gradual deformation scheme allows us for reducing the number of optimization parameters while selecting an optimal search direction. The numerical example compares the performance of the new gradual deformation scheme with that of the traditional one.     

Diffusion-controlled olivine corona textures in granitic rocks from Lofoten, Norway: calculation of Onsager diffusion coefficients, thermodynamic modelling and petrological implications

Reactions occurring during cooling of charnockitic intrusives on the Lofoten Islands produce characteristic diffusion-controlled textures around fayalite and Fe–Ti oxides. Thermobarometry indicates the corona textures formed at 780–840 °C and pressures of 4–10 kbar, whereas the magmatic assemblage of the charnockite (clinopyroxene–olivine–quartz) crystallized at about 850–870 °C and 4 kbar. The succession olivine|orthopyroxene+magnetite|orthopyroxene+garnet and olivine|orthopyroxene+magnetite|amphibole developed where olivine reacted with adjacent plagioclase or K-feldspar, but the modes and the thicknesses of the corona textures vary according to the feldspar type, indicating that the primary magmatic ternary feldspar was already exsolved into albitic plagioclase and alkali feldspar when the corona formation began. Simultaneously, in other parts of the rock, primary magmatic clinopyroxene reacted to amphibole and Fe–Ti oxides reacted to orthopyroxene+garnet coronas or to amphibole. Textures demonstrate significant Al diffusion in the rocks under granulite facies conditions and they suggest that no pervasive fluid influx occurred and that amphibole formation was dependant on a local source of H₂O probably related to water-release during the last stages of magmatism. Calculation of the net reaction by accounting for all observed reactions at different sites in the rock indicates that the system can be regarded as balanced on a hand-specimen scale with respect to all elements except for Na and H₂O. The larger variety of textures developed in rocks of granitic bulk composition provide more constraints than textures from gabbroic compositions, and permitted calculation of a set of relative diffusion coefficients which also reproduce textures in the gabbroic and anorthositic rocks from the Lofoten Islands. The following set of relative diffusion coefficients (L_i/L_Fe) reproduces the observed textures in the Lofoten rocks: Si=0.82, Mg=0.59, Mn=0.05, Na=0.38, K=0.39, Al=0.05 and Ca=0.07.     

A Chemical Equilibrium Model for Natural Waters

This paper reviews the present status of the Pitzer chemical equilibrium model, which can be used to characterize the one-atmosphere activity coefficients of ionic and non-ionic solutes in natural waters as a function of temperature and ionic strength. The model considers the ionic interactions of the major seasalt ions (H, Na, K, Mg, Ca, Sr, Cl, Br, OH, HCO₃, B(OH)₄, HSO₄, SO₄, CO₃, CO₂, B(OH)₃, H₂O) and is based on the 25 °C model of Weare and co-workers. The model has been extended by a number of workers so that reasonable estimates can be made of the activity coefficients of most of the major seasalt ions from 0 to 250 °C. Recently coefficients for a number of solutes that are needed to determine the dissociation constants of the acids from 0 to 50 °C (H₃CO₃, B(OH)₃, H₂O, HF, HSO ₄ ^- , H₃PO₄, H₂S, NH ₄ ⁺ etc.) have been added to the model. These results have been used to examine the carbonate system in natural waters and determine the activity of inorganic anions that can complex trace metals. The activity and osmotic coefficients determined from the model are shown to be in good agreement with measured values in seawater. This model can serve as the foundation for future expansions that can examine the activity coefficient and speciation of trace metals in natural waters. At present this is only possible from 0 to 50 °C over a limited range of ionic strengths (<1.0) due to the limited stability constants for the formation of the metal complexes. The future work needed to extend the Pitzer model to trace metals is discussed.