Relationship between the transition frequency of local fluid flow and the peak frequency of attenuation

Local fluid flow（LFF） at the mesoscopic scale is the main dissipation mechanism of seismic waves in heterogeneous porous media within the seismic frequency band.LFF is easily influenced by the structure and boundary conditions of the porous media,which leads to different behaviors of the peak frequency of attenuation.The associated transition frequency can provide detailed information about the trend of LFF;therefore,research on the transition frequency of LFF and its relationship with the peak frequency of the corresponding attenuation（i.e.,inverse of quality factor） facilitates the detailed understanding of the effect of inner structures and boundary conditions in porous media.In this study,we firstly obtain the transition frequency of fluid flux based on Biot＇s theory of poroelasticity and the fast Fourier transform algorithm in a sample containing one repeating unit cell（RUC）.We then analyze changes of these two frequencies in porous media with different porous properties.Finally,we extend our analysis to the influence of the undrained boundary condition on the transition frequency and peak frequency in porous media with multiple RUCs.This setup can facilitate the understanding of the effect from the undrained boundary condition.Results demonstrate that these two frequencies have the same trend at low water saturation,but amplitude variations differ between the frequencies as the amount of saturation increases.However,for cases of high water saturation,both the trend and the amplitude variation of these two frequencies fit well with each other.

Simultaneous Removal of Surfactant Template from MCM-41 and Implantation of Transition Metal Complexes into Mesopores with Supercritical Fluid

The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.

Magma-Fluid Transition and the Genesis of Pegmatite Dike No.3,Altay,Xinjiang,Northwest China

Abstract: The physico-chemical conditions under which the pegmatite dyke No. 3 was formed were discussed in the light of fluid-melt inclusion evidence. Our results lend support to the frac-tionation of hydrothermal solutions from magma. For the pegmatite dike No. 3, the magma-derived hydrothermal solutions are dominated by NaCl + CO2 + H2O.

Computational fluid dynamics simulation of Hyperloop pod predicting laminar–turbulent transition

Three-dimensional compressible flow simulationswere conducted to develop a Hyperloop pod. Thenovelty is the usage of Gamma transition model, in whichthe transition from laminar to turbulent flow can be predicted.First, a mesh dependency study was undertaken,showing second-order convergence with respect to themesh refinement. Second, an aerodynamic analysis for twodesigns, short and optimized, was conducted with thetraveling speed 125 m/s at the system pressure 0.15 bar.The concept of the short model was to delay the transitionto decrease the frictional drag;meanwhile that of theoptimized design was to minimize the pressure drag bydecreasing the frontal area and introduce the transitionmore toward the front of the pod. The computed resultsshow that the transition of the short model occurred moreon the rear side due to the pod shape, which resulted in 8%smaller frictional drag coefficient than that for the optimizedmodel. The pressure drag for the optimized designwas 24% smaller than that for the short design, half ofwhich is due to the decrease in the frontal area, and theother half is due to the smoothed rear-end shape. The totaldrag for the optimized model was 14% smaller than that forthe short model. Finally, the influence of the systempressure was investigated. As the system pressure and theReynolds number increase, the frictional drag coefficientincreases, and the transition point moves toward the front,which are the typical phenomena observed in the transitionregime.

Fluid Shear Stress-Induced IL-8/CXCR Signaling Promotes Epithelial Mesenchymal Transition of Ovarian Cancer Cells

Objective Epithelial mesenchymal transition(EMT)plays a very important role in ovarian cancer metastasis,and IL-8 released from mechanosensitive cancer cells may contribute to the EMT process of solid carcinomas.In this study,we have explored IL-8 and its receptors signal transduction process of human ovarian cancer cells under conditions of FSS,and simultaneously detected the EMT process of ovarian cancer.Methods After the fluid shear stress was loaded,LightCyclerTM system and ELISA were employed to assay the IL-8 mRNA expression and protein production,respectively.Meanwhile,IL-8 reporter gene pEGFP1-IL8USCS was constructed for determining IL-8 gene transcriptional activation through gene transfer and flow cytometric analysis.RT-PCR,Northern blot and immunofluorescence were used to determine the expression of IL-8 receptor CXCR2 at mRNA and protein levels.IL-8 downstream signaling molecule NF-κB nuclear translocation was observed by immunocytofluoresent staining.Western blot was used to examine IκB phosphorylation and EMT-related protein.Results(1)The increase of IL-8 mRNA expression by shear stress was time-dependent.The expression increased when SKOV3 cells exposed to fluid shear stress for 1 h,reached the summits at 2 h,gradually decreased at 3 h and remained at a constant level at 4~12 h.Additionally,IL-8 expression was negatively associated with the intensity of shear stress.After SKOV3 cells were exposed to low fluid shear stress(1.5 dyne/cm2)for 1 h and 2 h,IL-8 mRNA expression increased near 68 and 52 times respectively as that of SKOV3 cells exposed to a high fluid shear stress of 5.0 dyne/cm^2.(2)The productions of IL-8 protein in SKOV3 cells subjected to shear stress were time-dependent.The secretion reached the summit when SKOV3 cells exposed to fluid shear stress for 5 h,then IL-8 secretion gradually decreased at 8 h of stimulation by shear stress.IL-8 secretion increased obviously when fluid shear stress(0.5,1.5,or 2.0 dyne/cm2)was exerted on SKOV3 cells for 1 h.Notablely,the secretion of IL-8 was the highest when SKOV3 cells subjected to fluid shear stress 1.5dyne/cm^2,which was near 6 or 7 times as that of SKOV3 cells subjected to high fluid shear stress(5.0 dyne/cm^2).(3)There was an increase in enhanced green fluorescent protein expression in pEGFPI-IL8USCS-transfected SKOV3 cells subjected to a fluid shear stress of 1.5 dyne/cm2 for 2 h,suggesting a flow shear stress induced IL-8 gene transcriptional activation;(4)CXCR2,which was constitutively present on the surface of SKOV3 cells,increased following exposure to fluid shear stress for 60 min.(5)Following the application of a shear stress of 1.5 dyne/cm^2,NF-κB p65 became detectable in the cell nuclei and Phosphorylated IκB in cell lysates increased significantly;(6)Compared with the control group,critical EMT-related proteins vimentin was upregulated,E-cadherin was downregulated after the application of the 1.5 dyne/cm2shear stress for 2 h,which suggested the EMT of ovarian cancer.Conclusions FSS triggered IL-8/CXCR2 signaling of SK-OV3 cells represents an early gene activation and the activation can be mediated through NF-κB.When the fluid shear stress-induced IL-8/CXCR signaling activated,the expression of EMT-related proteins changed.This observation suggested that fluid shear stress-induced IL-8 activation and the downstream signal pathways may have important contribution to the EMT process of ovarian cancer cells.

Discontinuity of mode transition and hysteresis in hydrogen inductively coupled plasma via a fluid model

A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to in- vestigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determi- native role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase （decrease） at the E to H （H to E） mode transition, indicating an improved （worsened） inductive power coupling efficiency.

Isotropic-Nematic Transition of Hard Ellipsoid Fluids

We numerically study the thermodynamic properties of a hard ellipsoid fluid by mainly focusing on its phase transition from an isotropic phase into a nematic phase （i.e. isotropie-nematic phase transition）. To improve the accuracy, precision, and efficiency of our computations, we attempt to employ the Wang-Landau NPT Monte Carlo algorithm in our simulations to calculate the function p（V） that gives the probability of arriving at the threshold density of the isotropic-nematic transition. Our results directly reveal that the nematic fluid phase, which is characterized by an ordered direction rather than an ordered configuration, appears and coexists with the isotropic phase when the aspect ratio a of the ellipsoid is located in a relatively narrow range of α = 2.0-2.25, and it becomes dominant and is fully established when α≥αcut = 2.25. We find that our estimated αcut is significantly lower than previously reported values of around 2.75. This prediction is further confirmed by the calculations of both the fluid reduced density and pressure of coexistence which show that the pressure grows up as the density increases and the probability function p（V） exhibits double peaks when the pressure enters the coexistence region. Based on these consistent results we are able to conclude that when α≥2.25 an ellipsoid fluid can fully display the nematic behavior. This study will place a useful and tight theoretical constraint on investigations of the isotropic-nematic phase transition in the future.

海陆过渡相页岩储层液岩作用机理及钻井液体系构建

我国海陆过渡相页岩地质储量大、资源丰度高,开发前景广阔。但钻井过程中井壁极易发生掉块、坍塌,导致井壁失稳影响钻井安全。本文通过钻井岩心观察、电镜和CT扫描、X射线衍射分析等相关实验,得到储层岩样矿物组分及微观结构等特征,结果表明:页岩气储层全岩主要含石英和黏土矿物,地层黏土矿物含量高达45.7%,且黏土矿物中不含蒙脱石,高岭石含量为35%,伊/蒙混层含量为26%;岩样表面纳微米孔隙和微裂缝发育,裂缝宽度在微米级并连通多条窄裂缝;通过岩液作用后晶层间距、表面张力、线性膨胀率和裂缝扩展变化分析,海陆过渡相页岩仅发生表面水化,揭示了海陆过渡相页岩气储层岩液作用机理。优选了水基钻井液抑制剂、封堵剂与润滑剂,构建了一套海陆过渡相页岩气储层的高性能水基钻井液体系,并对其展开了室内评价。钻井液常规性能、抑制性、封堵性、润滑性评价实验结果表明,该钻井液体系抗温100℃,高温高压失水6 mL,泥页岩膨胀率为1.03%,钻井液润滑系数整体小于0.15,体系30 min的API滤失量较基浆降低40%,可对地层微裂缝实现有效封堵,且生物毒性EC50值为37260 mg/L,属于无毒级别,能够满足海陆过渡相页岩气钻井作业施工对钻井液性能的要求并进行了现场应用,封堵防塌效果良好,可有效解决海陆过渡相泥页岩井壁失稳的技术难题。

大雷诺数下对称翼型的转捩判断与规律研究

围绕翼型的转捩问题,以NACA0012、NACA0015、NACA0018三种不同厚度的对称翼型为研究对象,基于TSST湍流模型的数值模拟方法,提出基于湍流强度的转捩判断方法并研究在5种大雷诺数条件下翼型表面流动的转捩规律,以期为风力机叶片设计提供新的参考思路。研究表明,基于湍流强度的转捩判断方法是有效、可行的,使用翼型表面湍流强度曲线的阶跃现象观测转捩,可有效避免转捩前流动扰动带来的影响。同时利用湍流强度的变化情况可为风力机叶片设计寻找最佳设计参数。研究发现,增大攻角和雷诺数使得翼型上翼面转捩位置前移、下翼面转捩位置后移。此外,随着攻角的减小、雷诺数的增大、翼型表面厚度的增加,在翼型转捩前的流动逐渐稳定。

三元采出液电脱水器过渡层处理技术研究

受三元采出液机械杂质含量高、油水乳化严重、稳定性增强影响,油水界面之间形成稳定过渡层,其具有高导电率的特点,造成原油脱水设备处理效率下降,电脱水器平稳运行困难。为提升脱水系统稳定性,重点攻关复合驱中间层的处理方法,明确过渡层的形成及稳定机理,创新研发了过渡层高效抑制药剂,从源头减少电脱水器内过渡层的富集,保障电脱水器平稳运行。同时,电脱水器放水得到明显改善,有效降低了下游污水站的处理难度。此外,为实现过渡层内油、水、固三相分离,完全从系统内剥离,形成了“消融沉降、提温离心”的减量化处理技术,经处理后油中含水率低于0.3%,可满足外掺条件。通过实施过渡层专项处理技术,有力保障了脱水系统平稳运行及外输原油保质保量。

超临界气体炮发射装置内弹道建模与数值分析

超临界二氧化碳相变发射是当前武器发射领域研究热点之一,为进一步扩展超临界气体炮发射的研究,基于高压发射技术和气体炮的基本原理,确立超临界相变发射装置的总体方案,对超临界态二氧化碳与火药燃气的换热过程进行拟合。以弹体发射速度为目标,根据热力学方程与内弹道方程,得到初始压力变化规律,建立了超临界相变气体炮发射模型。基于Fluent对超临界相变发射流场变化进行了研究,分析了相变发射装置内气流速度变化,得到了初始压力和弹体质量对弹体出口速度的影响规律以及弹体在不同运动时刻周边流体域的变化情况,总结了经验公式。与实验结果对比表明:设计的超临界相变发射方案符合弹体预定的发射指标,流体仿真模型可靠。

高硅花岗岩流体出溶作用的识别和意义

高硅花岗岩以暗色矿物含量低,富SiO_(2)、Rb,贫MgO、FeO、Sr、Ba为特征,富集稀有金属元素,其研究对于理解花岗岩成因演化、稀有金属元素富集和成矿过程至关重要。岩相学和地球化学特征指示其经历高程度的分异演化,H 2O等挥发分作为不相容组分在残余熔体中逐渐富集饱和,导致流体出溶在高硅花岗质熔体中,但如何识别这一过程是难点。文章从岩相学、地球化学、矿物学、金属稳定同位素(Li、Ba、Fe)等角度总结了高硅花岗岩中流体出溶作用的证据和指标。岩相学方面,晶洞构造、雪球结构、单向固结结构等特殊结构、构造的出现是流体出溶的重要标志;地球化学方面,极低的Nb/Ta值(<5)、Zr/Hf值、稀土元素四分组效应是流体-熔体相互作用的有效识别标志;矿物学方面,锆石蜕晶化作用、轻稀土元素富集及钾长石富Pb指示存在热液流体参与;金属稳定同位素方面,相对于普通花岗岩,高硅花岗岩通常富集重Li、轻Ba和重Fe同位素,流体-熔体相互作用很可能是主要控制因素。但部分地球化学指标还存在较大争论,在实际使用过程中需结合不同指标进行综合分析。经过岩浆演化和流体出溶两阶段的富集过程,稀有金属元素得以在出溶流体中极度富集进而成矿。

基于流固耦合的浸水钢弹簧浮置板减振效果分析

为养护维修浸水情况下的浮置板轨道,基于流固耦合理论建立浸水条件下钢弹簧浮置板振动模型,分析浮置板和基础结构间存在积水情况时,车致振动影响下不同浸水深度浮置板轨道的减振效果。结果表明:钢弹簧浮置板的板底积水影响浮置板结构的减振性能;当积水深度小于板侧空间高度的1/2时,隧道壁在其峰值频率63 Hz的振动已经增大5 dB左右;当积水深度达到板侧空间高度全满时,隧道壁加速度级在63 Hz处增大13.4 dB,增加约30.7%;隧道壁在63 Hz和80 Hz的振动级插入损失也分别增大13.36 dB和13.67 dB;浮置板板侧空间有1/2及以上的高度浸水,峰值频率对应的浮置板、隧道壁的垂向振动级较正常情况分别大5d B、10dB以上时,建议及时排水。

低流阻全外压平衡型膨胀节压降仿真计算

蒸汽管道温度高、敷设距离长,常采用补偿器补偿管道的热膨胀量。本文针对旁通直管压力平衡型膨胀节在压降上的不足,提出了一种DN500低流阻全外压平衡型膨胀节,采用Fluent软件对其压降进行计算,分析流体流通面积比和流体流向转变角度对其压降的影响。结果表明,当流体流通面积比为2.35,流体流向转变角度为25°~40°时,减阻效果最佳,且优于旋转补偿单元。根据仿真数据,拟合得到DN500低流阻全外压平衡型膨胀节的压降计算公式,能够快速进行压降计算,为实际工程应用提供理论依据。

西华山钨矿床中熔融包裹体的初步研究与矿床成因探讨

过去一直认为西华山黑钨矿石英脉是高中温热液充填而成。研究发现 ,在黑钨矿石英脉的绿柱石中存在与流体 (气液 )包裹体共生的流体 -熔体包裹体和熔融包裹体 ,表明形成黑钨矿石英脉的成矿流体是一种岩浆 -热液过渡性流体。

内蒙古克什克腾旗小东沟斑岩型钼矿床成岩成矿机制探讨

本文选取内蒙古克什克腾旗的小东沟斑岩型钼矿区作为研究区,它位于西拉沐伦钼矿带的西南部。对小东沟岩体进行了主微量元素、SHRIMP锆石U-Pb定年等地球化学方面的研究;对岩体中的钾长石和含矿矿物辉钼矿进行了普通铅同位素分析。小东沟岩体具有高硅富钾、REE含量低、Zr含量高、无负铕异常、高ε_(Nd)(t)、低Sr_i等特点,指示岩浆起源于加厚新生下地壳的熔融,同时具有高温、快速熔融、快速析离逃离源区的特点;小东沟岩体的SHRIMP锆石U-Pb定年结果为142±2Ma,对应140Ma左右主应力场由南北向转为东西向的构造体制大转折时期,这个时期大兴安岭处于伸展的构造环境下,底侵作用发育,地幔物质可以添加到下地壳熔融形成的岩浆中;对岩体钾长石和辉钼矿进行的普通铅同位素分析显示前者具有从造山带-地幔过渡的特征,后者则显示有地幔特征,说明成岩、成矿物质来自两个不同的源区,下地壳的岩浆和地幔含矿流体发生了混合。通过以上的分析,结合水-岩浆物理反应的实验结果,本文提出小东沟斑岩型钼矿床的成矿模式:大兴安岭地区在早白垩世伸展的构造背景下,地幔含矿流体加入受底侵作用加热的下地壳中使之熔融形成岩浆,随后更多的地幔含矿流体进入岩浆房,促使其迅速析离逃逸出源区,二者一起上升侵位。在岩浆温度较高时,地幔含矿流体和岩浆大致以较稳定的液态不混溶的状态共存;当岩浆和流体侵位到较浅深度时,压力下降,温度降低,晶体增多,流体-岩浆体系变得不稳定,岩浆被流体分割成许多很小的岩浆团。流体中H^+、K^+和各种成矿元素的存在使之必然会和岩浆或冷却后形成的岩石发生蚀变反应,并晶出成矿矿物,形成现在我们看到的具有浸染状矿化现象的小东沟斑岩型钼矿床。

上地壳环境中的流体作用与灰岩的脆—韧性转变

对取自西南非纳米比亚Damara造山带Waterberg断层带中的细粒灰岩的变形结构与亚微结构开展的多方面综合研究 ,揭示出在流体相遍布的上部地壳环境中 ,细粒灰岩的变形属性具有双重性 :脆性与晶质塑性。这种双重性突出表现在破裂与微破裂构造的广泛发育 ,以及细粒动态重结晶颗粒沿着破裂带 (面 )的出现。导致这种双重过程的主要因素在于岩石变形作用过程中流体相的介入。破裂与微破裂的出现 ,为流体相介入岩石变形提供了通道 ,使得流体相能够弥散于高应变带及高应变晶体内。水解弱化是流体相影响岩石变形的重要机理。流体相促进位错滑移与攀移 ,并加速应变颗粒的恢复作用 ,以协调破裂过程。

岩浆到热液演化的包裹体记录--以骑田岭花岗岩体为例

骑田岭花岗岩是燕山期花岗岩早期多阶段侵入复式岩体,岩石化学的研究表明它是富碱的、高分异的A型花岗岩,形成于板内拉张的构造环境。在其第二阶段中细粒黑云母花岗岩内广泛发育着厘米级至米级似伟晶岩囊状体和石英晶洞,它们是富挥发份岩浆固结的产物,代表岩石形成过程经历了明显的岩浆-热液过渡阶段。包裹体显微岩相学研究在骑田岭黑云母花岗岩的石英中发现熔体-流体包裹体和流体包裹体共存,这一结果进一步证实骑田岭中细粒黑云母花岗岩中的似伟晶岩囊状体和石英晶洞是花岗质熔体在岩浆-热液过渡阶段的产物。显微测温结果显示,熔体-流体包裹体的捕获温度大于530℃,说明岩浆热液过渡阶段的温度不低于该温度;闪锌矿中流体包裹体的均一温度在285～417℃之间,盐度为11.7%NaCleqv,代表了成矿流体的温度和盐度;流体包裹体的均一温度为172～454℃,代表热液阶段流体的温度。从中细粒黑云母花岗岩到似伟晶岩囊状体再到石英晶洞,岩浆-热液体系经历了富挥份熔体→熔体+高盐度流体→高盐度流体→低盐度流体的完整演化过程,形成了CaCl2-NaCl-H2O-CO2体系的岩浆热液流体。包裹体岩相学及激光拉曼探针分析结果显示,在流体包裹体和多晶熔体-流体包裹体中含有长石、方解石、金红石及金属氧化物等子矿物,暗示其所捕获的流体具有较强的成矿能力。

普光气田高含硫气井溢流压井期间井筒超临界相态特征

针对超临界流体状态下烃类、硫化氢、二氧化碳的特性,结合p—T—ρ图版和实际气体状态方程,以及普光气田高含硫化氢、二氧化碳气井的实际情况,计算得出普光气田烃类与硫化氢、二氧化碳构成的混合物的相态图;建立了相应的数学模型,模拟了高酸性高压气井环空温度、偏差因子、压力和体积膨胀情况。从模拟计算结果可以看出:高含硫气体在溢流压井期间,在井筒较长井段处于超临界状态,远离临界点附近区域,从超临界状态转向低压气态时体积较明显的膨胀但不剧烈,不会出现在超临界点附近处特有的瞬时体积急剧膨胀现象;普光气田气井的酸性气体运移至距地面12%左右(即1120m)井深时,有体积膨胀趋势,运移至距地面10%左右(即560m)井深时有较明显的膨胀特征。

斑岩铜(钼-金)矿床的成矿流体

斑岩铜矿是主要的铜资源,是矿床研究和勘查的重要目标。斑岩铜矿按其与板块构造的关系可分为2种:俯冲带斑岩铜矿和碰撞造山带斑岩铜矿,它们在成矿流体方面有很多区别,其中较大的差别是碰撞造山带斑岩铜矿的钾化蚀变带比俯冲带斑岩铜矿的钾化蚀变带强得多,且范围也相对较宽。文章简述了这2种斑岩矿床的主要地质特征,着重从流体包裹体、蚀变作用和稳定同位素研究来探讨斑铜矿床成矿流体的主要特征,包括成矿流体的成分、形成温度和压力,氢、氧、碳和硫稳定同位素组成。这两种类型的斑岩铜矿中主要发育5种包裹体:M熔体包裹体;Ⅰ液体包裹体;Ⅱ气体包裹体;Ⅲ含子矿物的多相包裹体和CO2_H2O包裹体。Ⅱ类和Ⅲ类包裹体常共存,且均一温度相似,表明成矿流体经历了不混溶和沸腾作用。在Ⅲ类含子矿物的包裹体中发现了含金属硫化物(黄铜矿、黄铁矿)和氧化物(赤铁矿、磁铁矿)子矿物。在斑岩金矿和碰撞造山带的斑岩铜矿中出现CO2_H2O包裹体,在斑岩的斑晶和一些早期石英脉的石英中可见到熔体包裹体以及熔体_流体包裹体,它们代表斑岩岩浆的样品,说明斑岩铜矿的形成经历了岩浆和热液阶段。最近的研究表明,斑岩铜矿的初始流体是中等盐度和密度的岩浆流体。这种流体在上升过程中因压力释放而发生沸腾,形成气体包裹体和含子矿物的高盐度包裹体。