地球内部物质组成及其性质的研究     

臧绍先  宁杰远 《地球物理学进展》1993,(2)

地球内部物质组成的研究涉及对地表现象的深入解释,与地球动力学、地球热结构及宇宙演化有着密切的关系.本文综述了这方面的研究结果及近期的进展,指出两种地幔模型的主要分歧点,讨论了地幔中的主要相变及与间断面的关系,对今后研究提出四点意见.  相似文献   

H~+,Li~+,Mg~(2+)∥Cl~-—H_2O四元水盐体系在-10℃时的平衡溶解度相图     

王继顺  高世扬  刘铸唐  王波 《盐湖研究》1993,(2)

本文利用等温溶解度法测定了H~+,Li~+,Mg~(2+)//Cl~-—H_2O四元水盐体系在—10℃±0.1℃时的溶解度并绘制了等温相图。相图由HCl·MgCl_2·7H_2O、MgCl_2·8H_2O、HCl·6H_2O和LiCl·2H_2O四个相区构成,只有一个零变量点I:LiCl·2H_2O+MgCl_2·6H_2O+HCl·MgCl_2·7H_2O+L_(?)利用坐标变换和直线外推法,对溶解度数据进行处理后,用湿渣结线法解决了低温平衡固相较难确定的问题。  相似文献   

三元体系Li~+,Mg~(2+)∥SO_4~(2-)—H_2O 25℃相关系及溶液物化性质的研究          下载免费PDF全文

李冰  房春晖  王庆忠  李军  宋彭生 《盐湖研究》1993,(3)

研究了三元体系Li~+,Mg~(2+)∥SO_4~(2-)—H_2O在25℃时的相关系和平衡液相的密度、粘度、折光率、电导等物化性质,该体系为简单共饱型,两段溶解度曲线对应于体系的两种原始组份Li_2SO_4·H_2O和MgSO_4·7H_2O的结晶区,无复盐和固溶体形成,亦无脱水作用发生,应用电解质溶液Pitzer模型检测该体系25C的溶解度,并用经验或半经验公式对平衡液相的密度和折光率进行了理论计算,计算值与实验值非常接近。  相似文献   

水汽瞬态相变的激波管实验研究进展     

傅云飞  龚闽卫  韩肇元 《气象学报》1997,55(4):453-465

从激波管内水汽瞬态相变实验研究的角度出发，探讨利用激波管理论及实验技术应用于人工影响降雨、消雹所涉及的云雾瞬态相变问题。首先介绍利用激波管研究水汽瞬态相变的概况，并介绍一些特殊激波管及实验状态的控制。然后介绍激波管内水汽相变过程研究的测试原理及方法。最后讨论在研究爆炸方法进行人工降雨、消雹和自然闪电、雷击等问题时，应用激波管理论及实验技术进行实验研究爆炸作用于云雾等微物理过程的方法和内容  相似文献   

确定精密重力仪相位滞后方法的研究   总被引：2，自引：0，他引：2       下载免费PDF全文

张贤林 《地球物理学报》1997,40(3):392-401

从系统辨识的原理出发,给出了确定精密重力仪相位滞后的一种方法,即记录精密重力仪在阶跃信号作用下的输出数据,利用这些数据对仪器的传递函数进行辨识,从而确定重力仪对各潮汐波产生的相位滞后角度.用这种方法对ET-21地潮重力仪进行了相位滞后的确定,并给出这台仪器对15个主要潮汐波的相位滞后角度.  相似文献   

气候噪声和气候系统的分维   总被引：8，自引：0，他引：8       下载免费PDF全文

辛国君 《应用气象学报》1997,8(1):85-91

根据相空间嵌入定理，按照Grassberger和Procaccia提出的计算分数维的方法，利用近百年来南、北半球地面气温资料，估算了气候吸引子的分数维，计算结果表明:气候吸引子的分数维南半球为3.3～3.7，北半球为3.2～3.7。它提供了气候吸引子的自相似结构的基本信息，表明模似气候系统最少需要4个独立变量。另外，还讨论了气候噪声对估算维数的影响。  相似文献   

Observation of gravity waves in a boreal forest     

X. Lee  H.H. Neumann  G. Hartog  R.E. Mickle  J.D. Fuentes  T.A. Black  P.C. Yang  P.D. Blanken 《Boundary-Layer Meteorology》1997,84(3):383-398

In this paper we report the results of the analysis of two 60-min wave events that occurred in a boreal aspen forest during the 1994 BOREAS (Boreal Ecosystems-Atmosphere Study) field experiment. High frequency wind and temperature data were provided by three 3-D sonic anemometer/thermometers and fourteen fine-wire thermocouples positioned within and above the forest. Wave phase speeds, estimated from information revealed by spectral analysis and linear plane wave equations, are 2.2 and 1.3 m s^-1 for the two events. The wavelengths are 130 m and 65 m respectively and are much larger than the vertical wave displacements. There is strong evidence from the present analysis and from the literature supporting our postulate that these waves are generated by shear instability. We propose that wind shear near the top of the stand is often large enough to reduce the gradient Richardson number below the critical value of 0.25 and thus is able to trigger the instability. When external conditions are favorable, the instability will grow into waves.  相似文献   

相转移催化合成乙酸苄酯的研究   总被引：4，自引：0，他引：4  

杨志成  张海峰 《华东地质学院学报》1996,19(1):73-78

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Phosphorus oxynitride PON, a silica analogue: structure and compression of the cristobalite-like phase; P –T phase diagram     

J. M. Léger  J. Haines  C. Chateau  G. Bocquillon  M. W. Schmidt  S. Hull  F. Gorelli  A. Lesauze  R. Marchand 《Physics and Chemistry of Minerals》2001,28(6):388-398

 The structure of the cristobalite-like polymorph of phosphorus oxynitride PON has been refined using neutron powder diffraction data. It is tetragonal, space group I&4macr;2d, Z=4. The four P–(O,N) distances are equal but the tetrahedron is compressed along c. In AX₂ or ABX₄ compounds, the tetragonal I&4macr;2d or I&4macr; structure is obtained when the average ratio of the cation to anion radius is below 1.186, whereas the tetragonal P4₁2₁2 or orthorhombic C222₁ structure is obtained at low temperatures for larger ratios. The cell parameters of this PON polymorph have been determined as a function of hydrostatic pressure by in situ angle dispersive X-ray powder diffraction in a diamond-anvil cell. Under truly hydrostatic pressure, a strong anisotropic behavior is observed with the c parameter being nearly incompressible. Very slight anisotropic stress strongly modifies the high-pressure behavior. According to the pressure-temperature conditions of treatment, three phases, cristobalite-, moganite-, and quartz-like, have been obtained by quenching experiments, and the P–T phase diagram of PON was derived. The high-pressure behavior of the α-quartz, moganite, and cristobalite-like polymorphs of PON and SiO₂ is discussed. Received: 7 August 2000 / Accepted: 21 January 2001  相似文献   

The crystal and magnetic structure of Li-aegirine LiFe3+Si2O6: a temperature-dependent study     

G. J. Redhammer  G. Roth  W. Paulus  G. André  W. Lottermoser  G. Amthauer  W. Treutmann  B. Koppelhuber-Bitschnau 《Physics and Chemistry of Minerals》2001,28(5):337-346

Single crystals of Li-aegirine LiFe³⁺Si₂O₆ were synthesized at 1573?K and 3?GPa, and a polycrystalline sample suitable for neutron diffraction was produced by ceramic sintering at 1223?K. LiFe³⁺Si₂O₆ is monoclinic, space group C2/c, a=9.6641(2)?Å, b= 8.6612(3)?Å, c=5.2924(2)?Å, β=110.12(1)^° at 300?K as refined from powder neutron data. At 229?K Li-aegirine undergoes a phase transition from C2/c to P2₁ /c. This is indicated by strong discontinuities in the temperature variation of the lattice parameters, especially for the monoclinic angle β and by the appearance of Bragg reflections (hkl) with h+k≠2n. In the low-temperature form two non-equivalent Si-sites with 〈SiA–O〉=1.622?Å and 〈SiB–O〉=1.624?Å at 100?K are present. The bridging angles of the SiO₄ tetrahedra O3–O3–O3 are 192.55(8)° and 160.02(9)° at 100?K in the two independent tetrahedral chains in space group P2₁ /c, whereas it is 180.83(9)° at 300?K in the high-temperature C2/c phase, i.e. the chains are nearly fully expanded. Upon the phase transition the Li-coordination changes from six to five. At 100?K four Li–O bond lengths lie within 2.072(4)–2.172(3)?Å, the fifth Li–O bond length is 2.356(4)?Å, whereas the Li–O3?A bond lengths amount to 2.796(4)?Å. From ⁵⁷Fe Mössbauer spectroscopic measurements between 80 and 500?K the structural phase transition is characterized by a small discontinuity of the quadrupole splitting. Temperature-dependent neutron powder diffraction experiments show first occurrence of magnetic reflections at 16.5?K in good agreement with the point of inflection in the temperature-dependent magnetization of LiFe³⁺Si₂O₆. Distinct preordering phenomena can be observed up to 35?K. At the magnetic phase transition the unit cell parameters exhibit a pronounced magneto-striction of the lattice. Below T _N Li-aegirine shows a collinear antiferromagnetic structure. From our neutron powder diffraction experiments we extract a collinear antiferromagnetic spin arrangement within the a–c plane.  相似文献