生态压力测度法在流域水资源生态压力空间格局分析中的应用研究

文章以辽宁中部某流域为研究区域,采用生态压力测度方法对流域的水资源生态压力进行测算。测算结果表明:研究流域的水资源生态压力指数在1.08~2.39,平均压力指数为1.42,区域水资源生态压力受人类经济活动影响较大;区域的水资源生态压力全局Moran指数均值为-0.3419,呈现较为显著的空间变差性;区域水资源生态压力局部Moran指数为-0.3218,呈现较低的变异中心。研究成果可以为区域水资源生态保护提供参考。

基于可视化的山西省土地压力测度及缓解途径研究

土地作为农业发展的基础和载体,同时面临经济建设和生态环境保护的需求.随着人类活动的加剧,土地面临着前所未有的压力.从农业发展、经济建设和生态环境保护三个角度,采用土地利用总体规划中期的现状数据与规划预期数据,对山西省土地压力进行科学测度,基于地统计学理论,对山西省土地压力空间分布格局进行可视化表达,进而分析成因并提出缓解土地压力的对策.结果表明:山西省土地压力具有明显的空间分异规律,土地综合压力指数呈团状和点状的分布格局,自北向南逐渐下降,中部局部地区略低于周边;耕地压力指数呈南北高、中间低,且东部略高于西部;建设用地压力呈中部高、四周低;生态用地压力呈由北向南逐渐递减的趋势.

“双碳”目标下我国煤炭减量化使用的压力指数测度研究

煤炭是我国能源供给的主体品种,煤炭使用是我国碳排放的主要来源,在双碳目标和能源保供给的双重约束下,煤炭减量化使用很迫切,但会给国民经济带来较大的压力。本文通过修正的等方差加权法测度我国30个省(区、市)煤炭减量化使用的压力。在全国层面的分析中,本文基于ARIMA模型与ARMA-EGARCH(1,1)模型,得到了煤炭减量化使用压力指数在2021~2035年有下降的趋势,且煤炭波动的风险处于可控范围的结论;在地区视角下的研究区域层面的分析中,本文基于ARIMA模型与灰色关联度模型,得到了煤炭减量化使用压力指数的变化趋势存在地区间、地区与全国层面的异质性,在2014年后异质性逐步降低,在2021年后异质性变化将进一步平稳等结论。应坚持“先立后破”的能源转型思路,大规模发展可再生能源,为煤炭减量化使用创造宽松的外部经济环境;要积极赋能煤资源型地区和煤炭企业进行自我转型,降低煤资源型地区的减煤压力。

中国超额住房贷款压力测度研究

本文从住房需求的角度构建均衡住房贷款的理论模型,估计中国4个直辖市超额住房贷款的压力及其决定因素。结果表明,超额住房贷款的规模取决于城市的地区收入、住房价格和首付比例;北京和上海存在较大的超额住房贷款压力,天津和重庆目前尚不存在超额住房贷款压力;拥有较高超额住房贷款压力的城市,住房价格往往高于其他城市,这些城市首付比例的杠杆效应也十分显著。

大凌河中上游水生态压力空间格局分析

结合生态压力测度模型对大凌河中上游水生态压力空间格局进行测算分析。分析结果表明,大凌河上游水生态压力指数为0.21~0.51,平均值为0.34。流域生态压力空间格局Moran指数均值为-0.3077,水生态压力指数空间变差性较显著。

中国金融压力的测度和时变特征研究——基于MIMIC和MS-AR模型的分析

金融压力反映金融体系的系统性风险,有效测度金融压力对于维持金融体系稳定具有重要意义。本文在系统分析金融压力影响因素和表现特征的基础上,运用多指标多因素(MIMIC)模型测算得到反映中国金融压力水平的金融压力指数,并运用马尔科夫区制转移(MS-AR)模型识别金融压力的时变特征。研究表明:模型测算得到的金融压力指数能够较好地反映中国的金融压力状况,对样本期内发生的极端风险事件均准确进行了响应;中国金融压力较难实现不同区制间的转换,低压力区制的持续性更强;中国金融压力水平的变化主要源于内部经济状况和外部经济形势的联动影响。针对模型结果,本文提出了相关政策建议。

Use of casing and its effect on pressure cells

Although pressure cells have been produced and installed successfully for decades,the accuracy of measured pressure is often inadequate.Due to large differences between the stiffness of pressure cells and the surrounding media,there is a considerable difference between applied pressure and that measured from pressure cells.It is often difficult and expensive to make a pressure cell with stiffness（modulus of elasticity） similar to the surrounding material in which it will be embedded.In order to improve this situation,a casing material with proportional dimensions is recommended as a means to obtain reliable results.In our study,the effect of using casing in the installation of pressure cells is investigated,providing the characteristics of casing.Some practical recommendations are presented to improve the accuracy of the results using casing.

Measuring the Internal Velocity of Debris Flows Using Impact Pressure Detecting in the Flume Experiment

Measuring the internal velocity of debris flows is very important for debris flow dynamics research and designing debris flow control works. However, there is no appropriate method for measuring the internal velocity because of the destructive power of debris flow process. In this paper, we address this problem by using the relationship between velocity and kinetic pressure, as described by surface velocity and surface kinetic pressure data. Kinetic pressure is the difference of impact pressure and static pressure. The former is detected by force sensors installed in the flow direction at the sampling section. Observations show that static pressure can be computed using the formula for static water pressure by simply substituting water density for debris flow density. We describe the relationship between surface velocity and surface kinetic pressure using data from seven laboratory flume experiments. It is consistent with the relationship for single phase flow, which is the measurement principle of the Pitot tube.

Experimental study on the effects of big particles physical characteristics on the hydraulic transport inside a horizontal pipe

This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.

Prediction of Pressure Gradient and Holdup in Small Eoetvoes Number Liquid-Liquid Segregated Flow

The segregated flow pattern, which occurs in a 26.1 mm diameter, horizontal, stainless steel test section, is investigated. Pressure gradient and in situ phase distribution data were obtained for different combinations of phase superficial velocities ranging from 0.05 m.s^-1 to 0,96 m.s^-1. For the current small Eoetvoes number liquid-liquid system （EOD=4.77）, the dominant effect of interfacial tension and wall-wetting properties of the liquids over the gravity is considered. The approach introduces the closure relationship for the case of turbulent flow m a rough pipe, and attempts to modify the two-fluid model to account for the curved interface. In present flow rates range, wave amplitudes were found small, while interfacial mixing was observed. An adjustable definition for hydraulic diame- ters of two fluids and interfacial friction factor is adopted. The predicted pressure gradient and in situ phase distribution data have been compared with present experimental data and those reported in the literature.

Ab initio Predictions of Structural and Thermodynamic Properties of Zr2AIC Under High Pressure and High Temperature

The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.

RELATIONSHIP BETWEEN P-T CONTITIONS OF TWO PHASES OF TAN-LU STRIKE-SLIP SHEAR ZONES AND DELAMINATION OF OROGENIC BELTS ON THE EASTERN MARGIN OF THE DABIE MOUNTAINS

The Tan-Lu fault zone joins the Dabie Mountains on its eastern margin, and offsets the Dabie and Sulu orogenic belts sinistrally for about 500 kin. On the basis of calculation of temperature and pressure experienced by the two phases of the fault zone as well as the thermo-chronological information on mylonite from the earlier and later Tan-Lu fault zones on the eastern margin of the Dabie Mountains, this paper discusses the delamination history and uplifting magnitudes of the Dabie Mountains from earlier Jurassic to earlier Cretaceous. From mineral assemblages, mineral deformation and muscovite-chlorite geothermometry calculation, it is known that the temperature experienced by the two phases of Tan-Lu fault zones are between 40℃ and 450℃, and the confining pressures are between 0.25Gpa and 0.36GPa for the earlier shear zones and 0.24-0.39GPa for the late shear zones. According to the geobarometry of Si-in-phengite and by considering shear heating and tectonic over-pressure, it is concluded that the maximum formation depths for the two phases of the ductile shear zones are not more than 12 kin. Differential formation depths for the two phases of shear zones are 1-2 km at most. At about 190 Ma and 128 Ma, the Tan-Lu fault zone experienced two phases of cooling events. During this period, the eastem margin of the Dabie Mountains experienced a tectonic calm period and no uplifting. According to information from the Tan-Lu fault zone, the uplifting magnitudes of the Dabie orogenic belts are not more than 12 km during the earlier Cretaceous.

Online dynamic measurement of saturation-capillary pressure relation in sandy medium under water level fluctuation

An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.

Nondestructive evaluation of mechanical properties of nanostructured Al-Cu alloy at room and elevated temperatures

The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)test were used for evaluating the mechanical properties of this alloy.The tests were conducted at 21℃ on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios(BPR)of 30:1 and 90:1.Furthermore,the tests were conducted at 200 and 400℃ on the samples that were processed at BPR of 90:1.Increasing BPR resulted in raising the final indentation load from(316±26)to(631±9)N and reducing the final indentation depth from 111 to 103μm.Regarding the samples that were processed at BPR of 90:1,increasing the test temperature from 21 to 400℃ resulted in decreasing the final load from(631±9)to(125±1)N and increasing the final depth from 103 to(116±1)μm.The sample processed at BPR of 90:1 and tested at 21℃ revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400℃ exhibited the lowest strength and the greatest deformability,as compared to all samples under study.

A New Method for Measuring the Stitch Length of Weft Knitted Fabric in a Static Environment

It is essential to measure the stitch length of weft knitted fabric in a static environment for economy and improving productivity. The image inputted was dealt with the digital image processing techniques： the paper carried out the transformation of grey scale; then removed impurities with filtering; the characteristic of the stitch structure was abstracted by using the Fourier transform technique. To obtain the stitch length more accurately, we should establish ageometric medal of the stitch lined on the digital image processing, which provides a way to transform the stitch length in the two-dimenslon space into a three-dimension space. This study provides a new methed for measuring the stitch length without damaging the fabric.

Influence of Hydrostatic Pressure on Compressive Strength of Self-consolidating Concrete

The design of unique chamber, in which the SCUWC （self-consolidating underwater concrete） can be tested under the impact of the hydrostatic pressure from 0.1 MPa to 0.5 MPa, is presented in the paper. The results of the preliminary tests of the effect of the hydrostatic pressure on the compressive strength of SCUWC were shown. The impact of the hydrostatic pressure on the compressive strength values of test specimens has been confirmed. There has been an increase in the strength of the specimens taken from the upper parts of the concrete samples. As it can be seen from the preliminary research, the differences in compressive strength are related to the differences that occur in the size and distribution of air voids in the samples taken from upper and lower parts of the test specimens. On the basis of the carried out investigations of the compressive strength, it can be concluded that the hydrostatic pressure has a favorable effect on the compressive strength of the tested specimens of SCUWC. Increase of the compressive strength is observed mostly in the upper layers of the samples. Preliminary analysis of the quantity and distribution of air pores in the samples of concrete subjected to pressure 0.5 MPa confirms the positive impact of the hydrostatic pressure on the layers close to the surface indicated by the absence of large air voids above 1,500μm and by reducing the quantity of air pores of size above 300μm.

A fast explicit finite difference method for determination of wellhead injection pressure

A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected.

A new adaptive bending method using closed loop feedback control

As the competition from companies in low cost countries increases,the need for more automated production which reduces labour cost while improving product quality is required.A new rotary compression bending set-up with automated closed-loop feedback control is thus being developed.By transferring in-process measurement data into an algorithm for predicting springback and bend angle prior to the unloading sequence,the dimensional accuracy is improved.This work focuses on the development of this steering model.Since the method used does not increase cycle time,it is attractive for high-volume industrial applications.More than 150 bending tests of AA6060 extrusions were conducted to determine the capability of the technology.The results show that by activating the automated closed-loop feedback system,the dimensional accuracy of the bent parts is more than three times better than that obtained by traditional compression bending.Since the steering model permits the direct use of additional process data,such as instant wall thickness and cross sectional distortions,it is believed that extension of the measurement capabilities would improve the accuracy of the methodology even further.

Solubility of Paclitaxel in Mixtures of Dichloromethane and Supercritical Carbon Dioxide

Phase behavior of paclitaxel in solvent mixtures of dichloromethane and supercritical carbon dioxide was investigated using a supercritical phase monitor.Cloud point pressures were determined as a function of temperature,pressure and paclitaxel content from 313.1 to 343.1K and pressures up to 33.52 MPa.The ternary mixtures exhibit a typical lower critical solution temperature behavior.When paclitaxel content increases,the single-phase region shrinks in size.Three cubic equations of state(Redlich-Kworng,Soave-Redlich-Kwong and Peng-Robinson equation of state) coupled with the van der Waals one-fluid mixing rules were selected to correlate the experimental data.The results indicate that SRK EOS coupled with two binary interaction parameters kij and lij can predict paclitaxel solubility for the best fit of experimental data.

Application of artificial neural networks and multivariate statistics to estimate UCS using textural characteristics

Before any rock engineering project,mechanical parameters of rocks such as uniaxial compressive strength and young modulus of intact rock get measured using laboratory or in-situ tests,but in some situations preparing the required specimens is impossible.By this time,several models have been established to evaluate UCS and E from rock substantial properties.Artificial neural networks are powerful tools which are employed to establish predictive models and results have shown the priority of this technique compared to classic statistical techniques.In this paper,ANN and multivariate statistical models considering rock textural characteristics have been established to estimate UCS of rock and to validate the responses of the established models,they were compared with laboratory results.For this purpose a data set for 44 samples of sandstone was prepared and for each sample some textural characteristics such as void,mineral content and grain size as well as UCS were determined.To select the best predictors as inputs of the UCS models,this data set was subjected to statistical analyses comprising basic descriptive statistics,bivariate correlation,curve fitting and principal component analyses.Results of such analyses have shown that void,ferroan calcitic cement,argillaceous cement and mica percentage have the most effect on USC.Two predictive models for UCS were developed using these variables by ANN and linear multivariate regression.Results have shown that by using simple textural characteristics such as mineral content,cement type and void,strength of studied sandstone can be estimated with acceptable accuracy.ANN and multivariate statistical UCS models,revealed responses with 0.87 and 0.76 regressions,respectively which proves higher potential of ANN model for predicting UCS compared to classic statistical models.