Influence of Compaction Pressure on the Accelerated Carbonation of Calcium Hydroxide

Mineral carbonation using waste cement is a promising method to solve the problems caused by CO_2 emission and waste cement. Compaction pressure is an important parameter for mineral carbonation of calcium hydroxide, one of the most dominant composite of waste cement that can be carbonated. The carbonation degree, morphology of products and compressive strength of carbonated compacts are influenced by compaction pressure significantly. Results show that the carbonation degree of calcium hydroxide increases at first（0-8 MPa） and then decreases in the higher compaction pressure range（10-14 MPa）. At the meantime, results also indicate that lower compaction pressure accelerates the early carbonation but hinder carbonation in the later stages. For the morphologies of carbonation products, calcium carbonate tends to form typical crystal morphology of calcite（rhombohedral） under lower compaction pressure, while it will become ellipsoidlike when compaction pressure reaches 8 MPa. TGA and water content results show that there is an optimal water content for the carbonation. In addition, lower water content is adverse to the carbonation at later stage and the CO_2 is difficult to penetrate into the inside of compacts when water content is high, which will hinder the carbonation. XRD and TGA results show that the carbonation products are calcite and small amount of amorphous calcium carbonate.

CONSOLIDATION THEORY OF UNSATURATED SOIL BASED ON THE THEORY OF MIXTURE(Ⅱ)

The present paper uses the mathematics model for consolidation of unsaturated soil developed in ref.[I]to solve boundary value problems.The analytical solutions for one-dimensional consolidation problem are gained by making use of Laplace transform and finite Fourier transform.The displacement and the pore water pressure as well as the pore gas pressure are found from governing equations simultaneously.The theoretical formulae of coefficient and degree of consolidation are also given in the paper.With the help of the method of Galerkin Weighted Residuals,the finite element equations for two-dimensional consolidation problem are derived.A FORTRAN program named CSU8 using 8-node isoparameter element is designed.A plane strain consolidation problem is solved using the program,and some distinguishing features on consolidation of unsaturated soil and certain peculiarities on numerical analysis are revealed.These achievements make it convenient to apply the theory proposed by the author in engineering practice.

Site observations of weathered granitic soils subjected to cementation and partial drainage using SCPTU

Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test with pore pressure measurements has long been known for its reliability in site investigations and stratigraphic profiling.However,although extensive piezocone test results and experience are available for sedimentary soil,similar advances are yet to be made for weathered granitic soil.Moreover,the experience from sedimentary soil may not be directly applicable to weathered profiles because of the essentially different natures of the two types of geomaterials.This study performs seismic piezocone tests in a weathered granitic profile comprising residual granitic soil,completely weathered granite,and highly weathered granite.Pore pressure is measured at both the cone mid-face and the shoulder,and the effects of penetrometer size and penetration rate are considered.A series of updated soil behavior type charts is proposed to interpret the test results,thereby allowing the effect of weathering to be evaluated.This paper offers an important extension to the sparse data on the in situ responses of weathered materials.

The Numerical Simulation of Gas Turbine Inlet-Volute Flow Field

The structural and aerodynamic performance of the air inlet volute has an important influence on the performance of the gas turbine. On one hand, it requires the airflow flowing through inlet volute as even as possible, in order to reduce the pressure loss, to avoid a decrease in the effective output power and an increase of the fuel consumption rate of the internal combustion engine which indicate the inefficiency of the entire power unit;On the other hand, it requires the size of the inlet volute to be as small as possible in order to save mounting space and production costs. The thesis builds the structure model and develops flow fields numerical simulation of several different sizes of the inlet volutes. Further, the unreasonable aerodynamic structure is improved according to the flow field characteristics and thereby, a better aerodynamic performance of the inlet volute is obtained.

Relief Degree of Land Surface and Population Distribution of Mountainous Areas in China

Evaluation on the population pressure in the mountainous areas is a necessary condition for the protection and good governance. The evaluation depends on accurate population density assessment. Traditional methods used to calculate population density often adopt the administrative region as a scale for statistical analysis. These methods did not consider the effects of the relief degree of land surface(RDLS) on the population distribution. Therefore they cannot accurately reflect the degree of population aggregation, especially in mountainous areas. To explore this issue further, we took the mountainous areas of China as the research area. China has A total area of 666 km2 can be classified as mountainous area,accounting for 69.4% of the country's total landmass. The data used in this research included the digital elevation model(DEM) of China at a scale of 1:1,000,000, National population density raster data, the DEM and the national population density raster data. First, we determined the relief degree of land surface(RDLS). Next, we conducted a correlation analysis between the population distribution and the RDLS using the Statistical Package for Social Science(SPSS). Based on the correlation analysis results and population distribution, this new method was used to revise the provincial population density of themountainous areas. The revised results were used to determine the population pressure of different mountainous areas. Overall, the following results were obtained:(1) The RDLS was low in most mountainous areas(with a value between 0 and 3.5) and exhibited a spatial pattern that followed the physiognomy of China;(2) The relationship between the RDLS and population density were logarithmic, with an R2 value up to 0.798(p<0.05), and the correlation decreased from east to west;(3) The difference between the revised population density(RPD) and the traditional population density(PD) was larger in the southeastern region of China than in the northwestern region;(4) In addition, compared with traditional results, the revised result indicated that the population pressure was larger. Based on these results, the following conclusions were made:(1) the revised method for estimating population density that incorporates the RDLS is reasonable and practical,(2) the potential population pressure in the southeastern mountainous areas is substantial,(3) the characteristics of the terrain in the high mountainous areas are important for the scattered distribution of the population, and(4) the population distribution of mountainous areas in China should be guided by local conditions, such as social, economic, and topographic conditions.

Mechanism of high pressure roll grinding on compression strength of oxidized hematite pellets

The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.

Pressure-impulse diagram with multiple failure modes of one-way reinforced concrete slab under blast loading using SDOF method

Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.

Influential factors of loess liquefaction and pore pressure development

The liquefaction of loess under dynamic loading is studied experimentally with a dynamic triaxial test system. The effects of over-consolidation ratio (OCR), saturation degree and the frequency of dynamic loading upon loess liquefaction are investigated. The development of pore pressure within loess samples is also discussed. Based on the experimental results, the empirical relationship between pore pressure ratio and loading cycle number ratio is established for normal consolidated saturated loess.

Experimental and Numerical Study of Impact of Air Filter Holes Masking on Altitude at Heavy-Duty Diesel Engine

At high altitudes, power of an internal combustion engine reduces due to air density reduction. In turbocharged diesel engine this issue affects the performance of the compressor and can result in unstable operation of the turbocharger if the power is not decreased by engine actuator. Mainly for testing the effects of altitude in the test room, air throttle valve and combustion air handling unit were used to reduce the suction air pressure. Easier and cheaper solution to consider effect of altitude on engine performance is to mask part of the air filter to reduce the suction pressure. In this paper, pressure drop against 0%, 26%, 52%, 66% and 74% of air filter hole’s masking for different mass flow rates has been studied by computational fluid dynamics. The analysis output mass flow rate-pressure diagram for the air filter, will be used as input data in the GT-Power software which is a one-dimensional computational fluid dynamics software and the effect of masking on altitude and performance at different revolutions per minute of the engine is investigated. Also, an experimental and computational fluid dynamics study was carried out to predict altitude against different proportions of air filter hole’s masking at 1000 rpm. The predicted results are validated by comparing with those of experimental data. A good agreement between the predicted and experimental values ensures the accuracy of the numerical predictions with the present work.

Mixture Preparation and Combustion of CNG Low-Pressure Compound Direct Injection Spark-Ignited Engines

A set of compressed natural gas (CNG) multi-point direct injection system of spark-ignited engines and the corresponding measurement and data acquisition systems were developed in this paper. Based on different injection modes, the mixture formation and combustion of CNG low-pressure direct injection (LPDI) engines were studied under varying factors such as air/ fuel ratio, injection timing. Meanwhile, three-dimensional simulations were adopted to explain the mixture formation mechanisms of CNG low-pressure compound direct injection (LPCDI) mode. On the basis of test results and simulation of the mixture homogeneous degree, the conception of injection window was proposed, and the LPCDI mode was proved to be more beneficial to the mixture concentration stratification formation in cylinder under lean-burning conditions, which resulted in effective combustion and stability.

Inhomogeneous Dielectric Target Properties for Increased Non-thermal Pressure in Laser Boron Fusion by CPA-Pulses

Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-thermal forces using terms of extremely powerful components of Maxwell’s stress tensor at the interaction of CPA(chirped pulse amplification)laser pulses in the fusion plasmas of hydrogen with the isotope 11 of boron.This is caused by a recoil mechanism given by the Fresnel formulas of the suppression of the reflectivity of inhomogeneous plasma given by optical constants of the plasma properties.

Solution of Terzaghi one-dimensional consolidation equation with general boundary conditions

Boundary conditions for the classical solution of the Terzaghi one-dimensional consolidation equation conflict with the equation＇s initial condition. As such, the classical initial-boundary value problem for the Terzaghi one-dimensional consolidation equation is not well-posed. Moreover, the classical boundary conditions of the equation can only be applied to problems with either perfectly pervious or perfectly impervious boundaries. General boundary conditions are proposed to overcome these shortcomings and thus transfer the solution of the Terzaghi one-dimensional consolidation equation to a well-posed initial boundary value problem. The solution for proposed general boundary conditions is validated by comparing it to the classical solution. The actual field drainage conditions can be simulated by adjusting the values of parameters b and c given in the proposed general botmdary conditions. For relatively high coefficient of consolidation, just one term in series expansions is enough to obtain results with acceptable accuracy.

Pore structure of unidirectional solidified lotus-type porous silicon

Lotus-type porous silicon with elongated pores was fabricated by unidirectional solidification under pressurized hydrogen. Porosity, pore diameter, and pore length can be adjusted by changing solidification speed and hydrogen pressure. The porosity of the ingot is nearly constant under different solidification speeds, but decreases with the increase of hydrogen pressure. The overall porosities of ingots fabricated at different hydrogen pressures were evaluated through a theoretical model. Findings are in good agreement with experimental values. The average pore diameter and pore length increase simultaneously while the average pore aspect ratio changes slightly with the decreases of solidification speed and hydrogen pressure. The average pore length is raised from 7 to 24 mm and the pore aspect ratio is raised from 8 to 20 respectively with the average pore diameter promoted by about 0.3 mm through improving the superheat degree of the melt from 200 to 300 K.

Fuzzy Logic for Solving an Optimal Control Problem of Hypoxemic Hypoxia Tissue Blood Carbon Dioxide Exchange during Physical Activity

This paper aims at using of an approach integrating the fuzzy logic strategy for hypoxemic hypoxia tissue blood carbon dioxide human optimal control problem. To test the efficiency of this strategy, the authors propose a numerical comparison with the direct method by taking the values of determinant parameters of cardiovascular-respiratory system for a 30 years old woman in jogging as her regular physical activity. The results are in good agreement with experimental data.

Wellbore Cleaning Degree and Hydraulic Extension in Shale Oil Horizontal Wells

The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.

Degree One Loading by Pressure Variations at the CMB

Hemispherical asymmetry in core dynamics induces degree-1 pressure variations at the core mantle boundary （CMB）, which in turn deforms the overlaying elastic mantle, at the same time keeps center of mass of the whole Earth stationary in space. We develop a systematic procedure to deal with the degree-1 CMB pressure loading. We find by direct calculation a surprisingly negative load Love number h1=-1.425 for vertical displacement. Further analysis indicates that the negative hi corre- sponds to thickening above the positive load that defies intuition that pressure inflation pushes over- laying material up and thins the enveloping shell. We also redefine the pressure load Love numbers in general to enable comparison between the surface mass load and the CMB pressure load for the whole spectrum of harmonic degrees. We find that the gravitational perturbations from the two kinds of loads at degrees n〉l are very similar in amplitude but opposite in sign. In particular, if the CMB pressure variation at degree 2 is at the level of -1 hpa/yr （1 cm water height per year）, it would perturb the variation of Earth＇s oblateness, known as the J2, at the observed level.

Geobarmal Gradient in Orogenic Belt and Metamorphism Caused by Ultrahigh Pressure

The components and structures of lithosphere, inhomogeneous, are changing incessantly in different periods. Therefore, the state of load, called the pressure, in lithosphere is also incessantly changing. When the lithosphere volume remains the same, namely on the premise of isovolumes, the geobarmal gradient is: (d p /d h) v =( p / h) v +( p / T) v (d T /d h) v . If β =(d p /d h) v /( p / h) v is supposed, then β =1+ rg -1 C v (d T /d h) v . When the geothermal degree in (d T /d h) v is zero, then the pressure grade of lithosphere is equal to the lithostatic grade, which is the minimum value in the pressure grade of lithosphere. Suppose that the lithosphere is made only up of quartz, C v ≌ C p =0.782+5.718×10 -4 T -1.883×10 4 T -2 (J· g -1 · K -1 ) is obtained, which is the minimum one in lithospheric rock, and then the geothermal grade value of 20 ℃/km is calculated according to the geophysical transection data of Qinling Mountain orogeny. The results show that the high pressure and ultrahigh pressure eclogites in Jiangsu Province and Huangzhen, Dabie may, on the condition of incompletely isovolumes, occur in the depths of 17-40 km with the increase in geothermal temperature, whose values of β do not correspond to the theoretic value of 3.08.

四川盆地PT1井区海相地层工程地质特征研究

PT1井区超深海相地层钻井过程中气侵和井漏频发,严重制约该区块的安全高效开发。文章基于有效应力法,利用最优化方法开展了海相地层孔隙压力评价;结合断层和裂缝发育程度探讨了PT1井区气侵和井漏纵横向分布特征。结果表明,受异常高压和裂缝发育程度的双重影响,气侵主要发生在龙潭组,占比达40%;井漏主要发生在筇竹寺组和灯影组,占总漏失量的80%以上。气侵与异常压力、裂缝发育程度、断裂情况等因素有关,异常高压是气侵内在的原因,而断裂带和发育的构造裂缝为气侵提供了必要条件。井漏层位和漏失量主要受一、二级大型断裂带控制,不同断裂带的影响具有显著的叠加效应,断裂带附近发育的构造裂缝为漏失提供了通道,距离F I7断裂越近越易出现漏失,且漏失量越大。研究成果为PT1井区钻井过程井下复杂预防和处理提供了科学支撑。

热力耦合作用下有机类岩石渗透率演化规律及机理

在原位改性流体化采矿中,利用高温对矿床进行处理是一种有效方法。探明原位条件下有机类矿层的热解特性、细观结构、渗透率、变形等随温度的演化规律对资源的高效开采具有重要意义。利用高温高压三轴试验机结合含应力显微CT扫描技术,研究了热力耦合作用下3种有机类岩石(油页岩、烟煤及页岩)的渗透率、热解产气、细观结构及轴向变形随温度(≥300℃)的演化规律,同时结合热解产气、轴向变形及细观结构对渗透率演化机理进行了探究。结果表明:热力耦合作用下,有机类岩石的渗透率演化存在阈值温度,在轴压10 MPa,围压7 MPa的应力条件下,油页岩、烟煤及页岩的阈值温度分别为400、450及500℃;当热解温度小于阈值温度时,有机类岩石的渗透率由岩石强度主导,孔裂隙随温度的升高而闭合,渗透率与温度呈负相关变化;当热解温度大于阈值温度时,有机类岩石的渗透率由岩石的热解程度主导,孔裂隙随温度的升高逐渐发育并沟通,渗透率与温度呈正相关变化;进行阈值温度前后特性比较,油页岩热解程度与岩石强度在3种岩石中提升幅度最大,有机质热解并排出促进了孔裂隙的新生及连通,岩石强度的增大减弱了应力对岩石孔裂隙的压缩闭合作用,油页岩的渗透率呈现大幅度的提升。

基于PLC的油田注水全自动监控模型构建

油田注水全自动监控能够减少能耗,为实现油田注水全自动监控,构建一种基于PLC的油田注水全自动监控模型。首先设定监测目标,将注水量、供水量、注水井压力和注水井总流量作为约束条件,并建立基于油压、套压、注水水质、注水量、注水温度等预警指标,采用PID与PLC结合的方法实现油田注水全自动监控。实验结果表明,所提油田注水全自动监控模型在注水量监控、缓存罐液位监测、回水管路液体压力、油压监测等方面具有较高的准确性,能够满足方法设计需求,具有一定应用价值。