Sound velocity and density of liquid Ni68S32 under pressure using ultrasonic and X-ray absorption with tomography methods

A new experimental setup for simultaneous P-wave velocity (V_P) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (K_S) and to discuss the correlation between the V_P and ρ of the liquid sample. We measured V_P and ρ of liquid Ni₆₈S₃₂ up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the V_P and ρ values of liquid Ni₆₈S₃₂ is similar to that of liquid Fe₅₇S₄₃. (Both compositions correspond to near-eutectic ones.) The obtained K_S values are well fitted to the finite strain equation with a $K_{{\text{S}}_0}$ value (K_S at ambient pressure) of 31.1 GPa and a dK_S/dP value of 8.44. The measured V_P was found to increase linearly with increasing ρ, as approximated by the relationship: V_P [m/s] = 1.29 ρ [kg/m³] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dV_P/dρ slope is similar between Ni₆₈S₃₂ and Fe₅₇S₄₃ liquids, while the V_P–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the V_P–ρ relation of planetary and Moon's molten cores.     

Estimating absolute salinity (SA) in the world׳s oceans using density and composition

The practical (S_p) and reference (S_R) salinities do not account for variations in physical properties such as density and enthalpy. Trace and minor components of seawater, such as nutrients or inorganic carbon affect these properties. This limitation has been recognized and several studies have been made to estimate the effect of these compositional changes on the conductivity–density relationship. These studies have been limited in number and geographic scope. Here, we combine the measurements of previous studies with new measurements for a total of 2857 conductivity–density measurements, covering all of the world׳s major oceans, to derive empirical equations for the effect of silica and total alkalinity on the density and absolute salinity of the global oceans and to recommend an equation applicable to most of the world׳s oceans. The potential impact on salinity as a result of uptake of anthropogenic CO₂ is also discussed.     

Li2SO4溶液中离子间的缔合相互作用:基于密度泛函理论和分子动力学模拟的研究

基于密度泛函理论,使用B3LYP/aVDZ方法对[Li_2SO_4(H_2O)_n]~0(n=0~10、18)水合团簇的结构和性质进行了系统地研究,并结合Car-Parrinello分子动力学(CPMD)模拟了不同浓度的Li_2SO_4溶液结构,目的在于理解在Li_2SO_4溶液中离子间缔合相互作用及可能存在的物种。研究发现,对于[Li_2SO_4(H_2O)_n]~0(n=0~10、18)水合团簇,双配位单齿螯合接触离子对结构比双配位双齿螯合接触离子对结构更稳定,溶剂共享离子对结构最不稳定。同时,CPMD模拟结果表明,在3.09和3.17 mol/kg的Li_2SO_4溶液中,双配位单齿螯合接触离子对结构仍然是主要物种。以上结果表明在饱和的Li_2SO_4溶液(3.16 mol/kg)中,Li~+和SO_4~(2-)离子间的相互缔合作用主要以双配位单齿螯合接触离子对结构的物种存在,而具有双配位双齿螯合离子对结构的物种占少数,溶剂共享离子对结构几乎不存在。     

氯化物型和硫酸盐型卤水物性参数变化规律研究

在野外自然条件下光照和温度对盐湖卤水的物性参数有很大影响,在实验室条件下模拟一里坪盐湖卤水和黑北凹地卤水,研究了温度对氯化物型和硫酸盐型卤水多元体系的pH、黏度和密度的影响规律。结果表明,一里坪硫酸盐型和黑北凹地氯化物型卤水的pH和黏度随着温度升高而减小,密度随着温度升高而增大。     

Interdecadal variation of precipitation days in August in the Korean Peninsula

The present study examines a climate regime shift in the time series of the number of rainy days during August in the Korean Peninsula. The statistical change-point analysis indicates that a significant shift occurred in the time series around 1998, providing a rationale to divide it into two parts: 1975–1997 for the shorter rainy-day period and 1998–2012 for the longer rainy-day period. To examine the cause of recent rapid increases in the number of days with precipitation in August in the Korean Peninsula, differences in the averages of large-scale environments between the 1998–2012 period and the 1975–1997 period were analyzed.The differences in stream flows showed that anomalous cyclones were reinforced in the East Asian continent while anomalous anticyclones were reinforced in the western North Pacific at all layers of the troposphere. The anomalous anticyclones reinforced in the western North Pacific were associated with the western North Pacific subtropical high (WNPSH) developed a little more toward the Korean Peninsula recently. Consequently, the Korean Peninsula has been affected by anomalous south westerlies that supplied warm and humid airs from low tropical regions to the Korean Peninsula. The vertical thermal instability (warm anomaly at lower-level and cold anomaly at middle and upper-level) developed near the Korean Peninsula. In addition, upper tropospheric jets were reinforced further recently near the Korean Peninsula to provide good environments for development of upward flows. The frequency of TCs that affect the Korean Peninsula in August also increased rapidly since 1998.     

Analysis of Heat Budget, Dissipation and Frontogenesis in a Shallow Density Current

High frequency wind and temperature measurements, obtained in March 1995 from a 10-m tower array situated in south-east Kansas, are used to analyze the structure of a shallow density current. This current is approximately 7 m deep and exhibits a current head that is estimated to be about twice the current depth. The event lasted approximately 900 s and its origin appears to be a shallow slope 2–:5 km to the west of the site, where cold air drainage occurs. The onset of the event is marked by a 5 °C temperature decrease at the 3-m level, increased variance of temperature and of wind velocity, and increased dissipation of kinetic energy, measured by a hot-wire anemometer at the 3-m level. The primary contributors to temperature changes following the frontal passage are both horizontal and vertical advections; contributions from flux divergences of temperature and of radiation, and from dew formation, do not appear to be significant. Postulated frontogenesis, prior to the arrival of the apparent equilibrated front of approximately 176-m width at the site, is examined by means of a theoretical model. The time required to equilibrate the front, by means of kinetic energy dissipation within the frontal zone, is determined to be less than 300 s, or less than the estimated travel time from the orographic slope to the observational site. The absence of upstream data is determined, however, to be a limitation of the analysis performed.     

密度法与色度法描述印刷颜色之比较

文中作者着重从测量和计算两个方面,对密度法与色度法描述印刷颜色的优劣进行了分析和比较。     

基于比值均方根的杨氏模量反演方法

杨氏模量和泊松比是表征岩石脆性、评价储层可压性以及描述储层流体特征的重要参数,叠前地震反演是从地震数据中得到此类参数的有效手段.常规的叠前地震反演方法多使用Zeopppritz方程的近似式计算反射系数,近似式的误差影响了反演结果的精度.针对这个问题,推导了比值均方根形式的杨氏模量、泊松比和密度的Zoeppritz方程,并基于广义线性反演构建了杨氏模量和泊松比直接反演方法,有效地避免了使用近似式的局限性,提高了反演的精度.模型测试和实际资料试算结果表明：采用比值均方根形式构建的反演流程稳定,能够从叠前地震数据中获得可信的杨氏模量、泊松比和密度,提供了一种可靠的杨氏模量和泊松比直接反演方法.     

接收函数确定Moho面速度和密度跃变的方法研究及应用

通过对单层模型反射和透射系数的推导,提出了利用接收函数一次转换波和多次波确定Moho面速度和密度跃变的速度-密度跃变(δβ-δρ)扫描叠加方法.利用反射率法计算了不同模型的远震理论地震图,按照与处理实际观测波形一致的方法和流程计算了理论接收函数;根据不同模型数值试验结果,深入分析了界面速度和密度跃变对接收函数震相幅度的影响.利用(δβ-δρ)扫描叠加方法,对理论接收函数进行了数值试验,结果证明了该方法的可行性.最后将该方法应用于位于青藏高原东北缘的高台(GTA)台和兰州(LZH)台,确定了两个台站下方Moho面的速度跃变分别约为(19±1)%和(20±1)%,密度跃变最小值为(4±2)%和(6±2)%.     

青藏高原东南缘Moho面速度密度跃变研究

青藏高原东南缘地下深部结构的研究对了解青藏高原的变形机制和动力学过程具有重要意义.本文利用四川、云南固定台站记录到的远震波形资料,首先采用接收函数H-k叠加方法获得青藏高原东南缘台站下方的地壳厚度和波速比.进而利用接收函数一次转换波和多次波幅度信息确定了青藏高原东南缘Moho面上的S波速度和密度跃变.研究结果表明:研究区由南到北地壳厚度逐渐增加,从永德、沧源、孟连地区的33 km左右增至巴塘地区的69.7 km左右,厚度变化了近乎37 km.四川盆地和松潘甘孜块体南部的姑咱地区具有高泊松比、速度密度跃变较小特征,表明这两个地区含有较多铁镁物质.腾冲地区、龙门山西侧的汶川地区、四川盆地西南缘的沐川地区以及则木河断裂的石门坎至东川地区同属于高泊松比、速度密度跃变较大,显示这些地区壳内存在部分熔融.