顺层岩质边坡失稳破坏机理及滑动岩体临界长度分析

顺层岩质边坡常因工程建设活动中在坡体下部开挖形成临空面(剪出口)从而产生顺层滑移—拉裂破坏,在对顺层岩质边坡进行支挡设计时确定滑动岩体临界长度是设计人员最关心的问题。根据岩层面的抗剪强度指标通过边坡稳定性分析来确定滑动岩体临界长度。根据理论分析建立顺层岩质边坡失稳破坏长度计算式,结合习水县和播州区两个工程项目进行理论计算滑动岩体临界长度与实际岩体后缘拉裂长度对比印证,通过印证比对基本吻合。在对顺层岩质边坡进行开挖过程中应先进行预支护或预加固后方可进行岩体开挖。

基于临界压脚体的某滑坡体削坡压脚土方量平衡研究

针对某滑坡体治理时压脚土方量大于削坡土方量的问题,通过敏感性分析不同压脚体下滑坡体的安全系数发现,当压脚体的体积增大到一定程度后,滑坡体的抗滑稳定安全系数不再变化,由此提出基于临界压脚体进行滑坡体治理方案。分别对滑坡体高压脚少卸荷、低压脚多卸荷2种治理方案进行不同压脚体下的稳定性分析和土方量计算。分析结果表明,随着导流缺口占河床的比例逐渐减小,2种方案的全局搜索最小安全系数先增大,然后渐趋稳定;临界压脚体对应的导流缺口占河床比例均约1/2。基于临界压脚体进行滑坡体治理,可以较好地解决压脚土方量和削坡土方量的不平衡问题。

临界包裹体及其在金矿地质研究中的应用

临界包裹体具有在热动力过程中气液相比不变直至均一成一个流体相的特征 .它在超临界流体中 ,当临界体积为一定值时才能形成 .它可以在各类岩浆岩、火山岩、深变质岩以及铁、铜、金等多金属矿床中出现 .利用临界包裹体的临界均一温度结合该流体体系的相图 ,可以获得如成矿流体体系的热力学状态、流体基本组分特征、临界压力、盐度、密度等成矿物理化学信息 .通过多年研究发现 ,临界包裹体在中国北方深变质岩区的很多金矿床都有出现 ,它的临界均一温度都小于纯水的临界温度 ( 3 74 2℃ ) ,表明成矿早期的超临界流体是由一种低盐度CO2 -H2 O体系组成 ,它可能来自古老的深变质岩 .另一种较高盐度的成矿热液来自与矿床毗邻的中生代中酸性小岩体 .它们通过超临界流体成矿地质作用 ,形成了具有中国特色的多源多期多成因金矿床 .这在包裹体冷冻法及其成分分析和包裹体水的氢氧同位素分析的结果中也得到证实 .

超临界流体在化学反应中的应用

超临界流体可将化学反应的产物快速有效地移出反应体系，避免产物进一步发生副反应，并可提高反应速率或反应的转化率。在超临界流体介质中进行的化学反应，其反应速率可以大幅度提高。这些应用归因于超临界流体的特性，其中根本原因之一是超临界流体分子与溶质分子之间存在着超强相互作用，在宏观上这种作用表现为溶质具有绝对值很大的负的偏摩尔体积。

超超临界汽缸体铸件新型浇注系统研究

浇注系统对铸件质量具有决定性的影响。在本文中针对1 000 MW超超临界汽缸体铸件设计了带有排气道的浇注系统,排气道和直浇道关于铸件对称,以使初始浇注钢液冲洗完直浇道后进入出气端,从而保证浇注钢液的纯净。采用该浇注系统浇注了汽缸体铸件并对排气道进行了解剖夹杂物分析。对采用该新型浇注系统的汽缸体铸件的充型过程进行了数值模拟,并和传统的浇注系统的效果进行了对比分析。研究结果表明:采用带排气道的浇注系统有利于型腔内气体排出,使充型时钢液更平稳,对浇道冲击小,并且能有效减少铸件中的夹杂物缺陷,提升铸件质量作用明显。

面向新世纪挑战的瑞典汉学

本文介绍瑞典汉学自十七世纪以来的发展,以及当前所面临的问题及解决问题的思路。作者认为,不应该把汉学视为排他性的学科,主张在保持对古典研究的传统上,转为把现代中国文化作为主要研究领域,并提出了迎接新世纪时的四项工作重点。

Supercritical Fluid Extraction of Essential Oil from Dry Rhizome of Ligusticum chuanxiong Hort and Their Characterization by GC/MS

Supercritical fluid extraction (SFE) of essential oil from dry rhizome ofLigusticum chuanxiong Hort was developed. GC/MS was used for the determination of the composition ofessential oil. Forty-four compounds were identified. The conventional extraction method wasconducted in parallel for comparison. The extracts were qualitatively compared by GC/MS. The yieldsof SFE and steam distillation-extraction were 4.16 % ( v/w) and 0.8 % ( v/w), respectively.Application of SFE of zessential oil from dry rhizome of Ligustiaan chuanxiong Hort was preferable.

Studies on preparations and analysis of essential oil from Chinese fir

Three steam distillation devices (D-1, D-2 and D-4) or one simultaneous distillation (D-3, water-diethyl ether) as well as the process of CO2-SFE (Supercritical fluid extraction) were adopted in extraction of essential oils from Chinese-fir (Cunninghamia lancedata (Lamb) Hook.) and the chemical components of the extracted essential oil were analyzed by Gas chromatograph-MS analyses. The results showed that the essential oil could be almost extracted out within 2 hours and the device-3 had the highest extraction efficiency. The major chemical component of the oil was cedrol. The yield of the extracted essential oils from Chinese fir decreased gradually with the increase of the distillation time. The best condition for extraction by means of CO2-SFE is 100 kg·cm?2 in pressure and 40°C in temperature for. Keywords Chinese fir - Essential oil - Cedrol - Supercritical fluid extraction CLC number S781.4 Document code A Foundation item: This paper was support by the Key Foundation Research Project (G1999016001) of China and the Japan International Cooperation AgencyBiography: HUANG Luo-hua (1957-), male, Research associate, Research Institute of Wood Industry, Chinese Academy of forestry, Beijing 100091, P. R. ChinaResponsible editor: Song Funan

斜管沉淀池结构参数优化的理论分析

研究认为斜管沉淀池的结构参数(管径d、管长l、倾角θ)和控制参数(表面负荷q、管内流速)影响沉淀效率。分析了进入斜管内絮体的运动轨迹,并借助姚氏特征参数推求设计参数对临界沉速u0的影响情况;同时,对沿斜管内壁下滑的絮团进行受力分析,求取其对结构参数的最低要求。结果表明,u0与表面负荷q成正比,且存在满足絮团下滑条件的最大q;综合考虑絮体沉降和絮团下滑,不同q下存在较优管径d;考虑管长方向上的比临界沉速,斜管长度l可以选择为1.2～1.4m;q相同时,斜管倾角为35°～60°能基本满足絮团下滑的要求。

Linear numerical calculation method for obtaining critical point,pore fluid,and framework parameters of gas-bearing media

Up to now, the primary method for studying critical porosity and porous media are experimental measurements and data analysis. There are few references on how to numerically calculate porosity at the critical point, pore fluid-related parameters, or framework-related parameters. So in this article, we provide a method for calculating these elastic parameters and use this method to analyze gas-bearing samples. We first derive three linear equations for numerical calculations. They are the equation of density p versus porosity Ф, density times the square of compressional wave velocity p Vp^2 versus porosity, and density times the square of shear wave velocity pVs^2 versus porosity. Here porosity is viewed as an independent variable and the other parameters are dependent variables. We elaborate on the calculation steps and provide some notes. Then we use our method to analyze gas-bearing sandstone samples. In the calculations, density and P- and S-velocities are input data and we calculate eleven relative parameters for porous fluid, framework, and critical point. In the end, by comparing our results with experiment measurements, we prove the viability of the method.

Threshold pressure and infiltration behavior of liquid metal into fibrous preform

A dynamic measuring apparatus was developed to investigate the infiltration process of liquid metal into the fibrous preform. 10% （volume fraction） chopped carbon fiber preforms were infiltrated with magnesium alloy under different infiltration pressures. The threshold pressure and flow behavior of liquid metal infiltrating into the preforms were calculated and measured. The microstructure of obtained Ct4Mg composites was observed. The results indicate that the measured threshold pressure for infiltration was 0.048 MPa, which was larger than the calculated value. The infiltration rate increased with the increase of infiltration pressure, but the increase amplitude decreased gradually. The tiny pores in the composites could be eliminated by increasing the infiltration pressure. When the infiltration pressure rose to 0.6 MPa, high quality C1/Mg composite was obtained.

Effects of the profile of a supercavitating vehicle's front-end on supercavity generation

The authors designed three different front profiles for supercavitating vehicles based on cavity theory and the Granville streamlined equation are designed. Experiments were done using these front profiles in the Northwestern Polytechnical University high-speed water tunnel. The experiments indicated that the critical volume of gas required for supercavitation is affected by the axial distribution of the front-end＇s slope. The experimental data showed critical gas flow rates required for the three designs were less than rood-l, with the greatest decrease 24%. The experimental results also showed the supercavitation generation speeds of the models were faster than mod-1 by up to 32.4%. This verifies that the front profile of a supercaviting vehicle effects supercavity generation speed and critical gas flow rates. The smaller the changes in axial distribution of pressure, the higher the supercavity generation speed. The smaller the changes in curvature distribution of axial, the smaller the critical gas flow rates.

Self-diffusion Coefficient Model Based on Activation Energy and Free Volume

A new model for self-diffusion coefficients was proposed based oil both the concepts of molecular free volume and activation energy. The unknown parameters of this model were clearly defined and compared with the Chapman-Enskog model. At the same time a new method for calculating activation energy was devised and applied to the new model. In addition, the free volume was defined by implementing the generic van der Waals equation of state, the radial distribution function of which was obtained by using the Morsali- Goharshadi empirical formula. Under the same conditions, the new model was better than the original free volume model.

Advances in Supercritical Fluid Crystallization

The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritical fluid crystallization techniques, i.e. rapid expansion of supercritical solutions, supercritical fluid anti-solvent and particles from gas saturated solutions Some questions and the prospect of this technique were also discussed.

Supercritical Antisolvent Precipitation of Microparticles of Quercetin

Supercritical antisolvent (SAS) process is a recently developed technology to produce micro- and nano particles. This paper presents a continuous apparatus to conduct experiment of SAS process. With the apparatus, the effects of pressure, temperature and flow ratio of CO2 to the solution on the shape and size of particles are studied for the quercetin-ethanol-CO2 system. Spherical quercetin microparticles with diameters ranging form 1 μm to 6μm can be obtained while ethanol is used as organic solvent. The most effective fact on the shape and size of particles is pressure, the next is temperature and the last is the flow ratio of CO2 to solution.

Production of De-asphalted Oil and Fine Asphalt Particles by Supercritical Extraction

A continuous three-stage supercritical fluid extraction (SFE) process with a capacity of 1.0kg.h^-1 was setup to extract petroleum residue by pentane to obtain more oil for further upgrading. A discharging system integrated to the bottom of the extractor was used to recover solvent as gas while asphalt was obtained as fine particles. The influence of operating conditions on the yield and quality of extracts, i.e., deasphalted oil (DAO) and resin, was studied in the range of temperature 150-220℃, pressure of 4.0-6.0 MPa and the mass ratio of solvent to oil feed (S/O) 2.5-5.0. The particle size distribution, apparent forms and the packing density, which vary with operating pressure, were measured. The particle structures were observed by SEM as well. With the modification to conventional processes, furnace can be eliminated for solvent recovery from asphalt phase, so as to reduce energy consumption.

A Mathematical Method for Determination of Absolute Adsorption from Experimental Isotherms of Supercritical Gases

A mathematical method was proposed for the determination of absolute adsorption from experimental isotherms. The method is based on the numerical equality of the absolute and the excess adsorption when either the gas phase density or the amount adsorbed is not quite considerable. The initial part of the experimentalisotherms, which represents the absolute adsorption, became linear with some mathematical manipulations. The linear isotherms were reliably formulated. As consequence, either the volume or the density of the supercritical adsorbate could be determined by a non-empirical way. This method was illustrated by the adsorption data of supercritical hydrogen and methane on a superactivated carbon in large ranges of temperature and pressure.

Combination of Supercritical Fluid Extraction with Ultrasonic Extraction for Obtaining Sex Hormones and IGF-1 from Antler Velvet

Supercritical CO2 (SC-CO2) extraction technology and ultrasonic technology were used to extract two active sex hormones, estradiol and progesterone, and insulin-like growth factor-1 (IGF-1) from antler velvet. The effects of SC-CO2 extraction condition on the extraction yield and content of sex hormones, the ultrasonic extrac-tion condition on the content of IGF-1 and the SC-CO2 extraction condition on the activity remaining of IGF-1 were studied. The optimal conditions were obtained. The experimental results showed that, in presence of 75% ethanol as the co-solvent, the mean yield and content of estradiol and progesterone were 87.67 pg·g-1 and 1224.10 pg·g-1, 12.38 ng·g-1 and 354.06 ng·g-1, respectively, with extraction pressure of 30 MPa, temperature of 35°C, extraction time of 30 min and CO2 consumption of 15 L·g-1 at the flow rate of 2.0 L·min-1. The highest content of IGF-1 was 7425.75 ng·g-1 antler velvet residue, when the pH10 ammonia-ammonium chloride buffer solution was used as the solvent, the ratio of solvent to sample was 20/1 (volume/mass), the extraction temperature was 0-35°C, and the ex-traction time was 4×15 min. Under these conditions, 93.68% activity remaining of IGF-1 in the residue was ob-tained, while little IGF-1 activity exists in traditional residue. The experimental results indicate that the technology of SC-CO2 with co-solvent is of advantage for getting high content sexual hormones and keeping high activity of IGF-1 in the residue, which can not be achieved by traditional extraction methods.

Measurement and Correlation of Solubilities of C.I. Disperse Red 73,C.I. Disperse Blue 183 and Their Mixture in Supercritical Carbon Dioxide

The solubility of disperse dyes and their mixture in supercritical carbon dioxide is an important property in study and development of supercritical fluid dyeing technology.In this study,solubilities of C.I.Disperse Red 73,C.I.Disperse Blue 183 and their mixture in supercritical CO2 are measured at temperatures from 343.2 to 383.2 K and pressures from 12 to 28 MPa with a static recirculation method.Under the experimental conditions for the binary(C.I.Disperse Red 73+CO2 or C.I.Disperse Blue 183+CO2) and ternary(C.I.Disperse Red 73+C.I.Disperse Blue 183+CO2) systems,the solubilities increase with pressure.The solubility of C.I.Disperse Blue 183 decreases with the increase of temperature when the pressure is lower than 16 MPa,and the trend is opposite when the pressure is higher than 16 MPa.However,there is no crossover pressure for C.I.Disperse Red 73.The solubilities are also affected by molecular polarity of dyes.The co-solvent effect exhibited in the dissolving process of mixed dyes promotes their dissolution in supercritical CO2.The experimental data of solubilities of C.I.Disperse Red 73,C.I.Disperse Blue 183,and their mixture are correlated with the Chrastil model and Mendez-Santiago/Teja model. The former is more accurate.

Dynamic Supercritical Fluid Devolatilization of Polymers

A number of studies have been reported on the applications of supercritical fluids to polymeric processes. The presence of volatiles can affect the end-use properties of polymer materials. Therefore, these volatiles must be reduced to a level below the maximum permissible limit. Conventional heat-relevant techniques for polymer devolatilization sometimes have limited effectiveness. Devolatilization with supercritical fluids, however, can enhance removal of volatiles from polymers. A model for diffusion-limited extraction is used to characterize dynamic supercritical fluid devolatilization of spherical polymer particles. The rate of supercritical fluid devolailization for styrene/polystyrene system is measured at 343 K and 18 MPa and at CO2 flow rate of 1.93, 3.27 and 5.62 L·min^-1, respectively. The model analysis, which is consistent with experimental results, indicates that the supercritical fluid devolatilization is not solubility-limited but diffusion-limited when CO2 flow rate is above 4.00 L·min^-1.