Comprehensive evaluation of water quality parameters in Tianjin Dagu Dainage Canal

In this paper, some indices of sulfide, organic carbon, oil and heavy metals （copper, lead, zinc, cadmium, mercury, arsenic and chromium） in the sediments from Dagu Dainage Canal at the Bohai Bay during four seasons in 2012 - 2013 are selected, and Water Quality Pollution Index （API） is applied to evaluate water quality indices, aiming for the systematic evaluation of the water quality of Dagu Dainage Canal. The results showed that four stations of D3, D6, D7and D9 for S2 had the type Ⅱand Ⅲ of water; others had the type Ⅰ ; the total level of TOC, TPH, Cu, Pb, Zn, Cd, Hg, As and Cr were type Ⅰ, Ⅳ, Ⅱ, Ⅴ, Ⅱ, Ⅴ, Ⅲ, Vand Ⅴ. Water Quality Pollution Index （API） was 3.28, which illustrated Dagu Dainage Canal was in the state of contamination and the degree of pollution exceeded the standard functional areas.

Detection of gas hydrate sediments using prestack seismic AVA inversion

Bottom-simulating reflectors (BSRs) in seismic profile always indicate the bottom of gas hydrate stability zone, but is difficult to determine the distribution and features of gas hydrate sediments (GHS). In this study, based on AVA forward modeling and angle-domain common-image gathers we use prestack AVA parameters consistency inversion in predicting gas hydrate sediments in the Shenhu area at northern slope of South China Sea, and obtain the vertical and lateral features and saturation of GHS.

Effect of gelcasting conditions on quality of porous Al-Cu alloy

The porous A1-Cu alloy was prepared by the gelcasting process. And the effects of gelcasting conditions, such as monomer, the volume ratio of cross-linker and monomer, dispersant and redox initiating system on the height, gelling time and the quality of green body were investigated. （It was found that the dispersant and monomer played significant roles in the height and quality of green bodies, respectively.） The optimal conditions were 10% monomer, 2% cross-linker, 0.2% initiator （volume fraction）, and 1.2 g dispersant, in which the green body exhibited the best quality. The mechanisms of process conditions in eliminating the cracks and forming the pores of in the five stages were proposed. Mercury porosimetry provided a description of pore diameter ranging from 10 to 10000 nm and open porosity of 38.78 %.

Determination of photosynthetic parameters in two seawater-tolerant vegetables

It is difficult to determine the photosynthetic parameters of non-fiat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters （such as PN, gs, E） based on unit fresh mass, instead of leaf area. The light/COftemperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.

Sensitivity Analysis of Petrophysical Parameters for Estimating Hydrate Saturation in the Shenhu Area

Acoustic and electrical methods are commonly used to evaluate hydrate saturation based on P-wave velocity(Vp)and resistivity,respectively.We evaluate hydrate saturation using petrophysical parameters directly related to the presence of hydrates.Five petrophysical parameters sensitive to hydrate saturation were first analyzed using the equivalent medium rock physical model,logging intersection plots,and petrophysical parameter inversion.The simulated annealing global optimization method was then used to estimate the hydrate saturation profile in the Shenhu Area,China.The petrophysical parameters Vp,λρ,andλμ,which are associated with the rock elastic and shear moduli,are highly sensitive to hydrate saturation for an estimated saturation range of 0.1-0.44.This range is consistent with that obtained from the original well diameter curves.However,the parameters Vs andμρ,which are only related to the rock shear modulus,yield high hydrate saturation estimates of 0.22-0.43 and exhibit some deviations from the real-time data.Owing to its sensitivity,the Poisson’s ratio is least desired for hydrate evaluation among the studied parameters.The sensitivity of hydrate saturation depends on the petrophysical model used for studying hydrate physical properties and storage analysis.

Reasonable location parameters of pick and nozzle in combined cutting system

The drum shearer and high pressure water jet combined cutting system is an effective technology to cut hard coal-rock, but one problem of the technology is the choice of pick and nozzle location parameters. In order to solve the problem, the process and mechanism of combined cutting arc studied and mining seepage catastrophe theory is used to construct the mathematic and physical model of combined cutting hard coal-rock. Based on the model and detailed analysis of combined cutting mechanism, the single pick and nozzle combined cutting test-bed is built to test the main pick and nozzle location parameters of drum shearer and water jet combined cutting system. Test results show that the best vertical distance between the pick-tip and nozzle center point is the sum of cutting thickness and proper target distance in the Y axial direction; the best horizontal distance is the length between pick-tip point and coal-rock surface bursting crack point in the X axial direction. The best incident angle of water jet should be the same as the bursting crack line＇s angle in theory, but considering other important factors comprehensively, it is more reasonable when the incident angle of water jet is 90°.

镁渣脱硫剂的水合及添加剂改性研究

在实验室条件下通过镁渣和粉煤灰的水合反应,制备了可用于循环流化床锅炉的脱硫剂。采用热重分析方法对不同水合条件下的脱硫剂的钙转化率进行了研究;借助X射线衍射分析研究了水合前后以及脱硫前后物质的变化,并分析水合以及脱硫反应的原理。在此基础上研究了水合过程中不同添加剂的影响。结果表明,在最佳水合条件下,所制备的脱硫剂的钙转化率可达36.70%,最佳的脱硫反应温度为920℃。水合过程添加乙二酸或氢氧化钠,脱硫剂钙转化率最大可以进一步提高至73.7%。

Removal of strontium ions from aqueous solution using hybrid membranes: Kinetics and thermodynamics

The removal of radionuclide from radioactive wastewater has captured much attention.Strontium-90 is one of the major radionuclides.To develop a new type of adsorbents to remove strontium ions from the radioactive wastewater,in this study,novel hybrid membranes were prepared and characterized.The adsorption kinetics,thermodynamic parameters of AG,AH and AS,as well as surface SEM and EDS images were used to investigate the removal of strontium ions from stimulated radioactive wastewater using the previously prepared hybrid membranes as efficient adsorbents.The study of kinetic model confirmed that the adsorption of strontium ions on these hybrid membranes followed the Lagergren pseudo-second order model.Moreover,it was proved that the adsorption of strontium ions on these samples was solely controlled by intraparticle diffusion.The negative values of AG and the positive values of AH indicated that the adsorption of strontium ions on samples A-D is a spontaneous and endothermic process in nature.Furthermore,surface SEM and DES images give significant evidence to confirm the existence of strontium ions on the surface of the adsorbed samples.These findings demonstrate that these hybrid membranes are promising adsorbents for the removal of strontium ions from aqueous solution and can be potentially applied in the adsorptive separation of radionuclides from the radioactive wastewater.

激冷水合改性镁渣脱硫剂性能实验

为了达到以废治废的目的,对镁冶炼产生的废弃物-镁还原渣通过激冷水合方式制备脱硫剂进行研究。采用XRD获得不同激冷条件下样品的物质组成,通过SEM研究炽热镁渣激冷样品的表观形貌。通过实验室激冷水合实验研究不同水合参数对水合反应以及脱硫性能的影响。对比现场炽热镁渣激冷水合与实验室激冷水合活化方式下水合样品的脱硫性能。结果表明:镁渣激冷后的主要成分为β-C2S,且表面变得粗糙多孔;脱硫钙转化率与水合反应程度间存在抛物线关系;当激冷温度为950℃,水合温度为50℃,实验室炽热镁渣激冷水合反应所制备的脱硫剂在水合时间为6 h时,钙转化率最高,为14.1%,而水合时间为8 h时,水合反应程度最大,为0.16 g·g^(-1);与实验室炽热镁渣激冷水合样品和自然冷却水合样品相比,现场炽热镁渣激冷水合样品的钙转化率最高,达30.33%。

An Analytic Solution to Well-water Level Changes under Barometric Pressure

Under barometric pressure, groundwater flow in well-aquifer systems is a kind of hydromechanical coupling problem. Applying the flux boundary conditions on borehole wall and water pressure equilibrium conditions inside and outside the borehole wall under barometric pressure （BP）, an analytic solution to well-water level changes has been proposed in this paper. The formulation shows that the BP coefficients increase with time and tend to BP constant. The Change of BP coefficients over time depends only on the ratio of transmissivity （T） to the well radius squared （ r2, ） , and has nothing to do with the change in BP. The BP constant only relates to aquifer loading efficiency （B）, and has nothing to do with the aquifer transmissivity and well radius. The BP coefficients＇ change over time in the analytic formulation is consistent with the analysis of measured data from the Nanxi wells. Based on the BP coefficient changes over time, a parameter estimation method is suggested and discussed in its application to the estimation of the aquifer BP constant （or B） and transmissivity by using the Nanxi well data.

Effects of Biochar and Super Absorbent Polymer on Substrate Properties and Water Spinach Growth

Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar （0-160 mL L-1） and super absorbent polymer （SAP, 0.8 g L-1） on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach （Ipomoea aquatica Forsk）. Total porosity, water-holding capacity~ pH and electrical conductivity （EC） of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of pH and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates （100-160 mL L-l）. The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone （76.9%-83.7%）, whereas the rates increased to 83.6%-85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 mL L-1. There were significant cubic relationships between the uptake of nutrients （N, P, and K） and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth, the biochar application rate should be controlled at an optimal level （100 mL L-1 ）. The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of pH and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.

Simultaneous estimation of surface soil moisture and soil properties with a dual ensemble Kalman smoother

In this paper, a new state-parameter estimation approach is presented based on the dual ensemble Kalman smoother(DEn KS) and simple biosphere model(Si B2) to sequentially estimate both the soil properties and soil moisture profile by assimilating surface soil moisture observations. The Arou observation station, located in the upper reaches of the Heihe River in northwestern China, was selected to test the proposed method. Three numeric experiments were designed and performed to analyze the influence of uncertainties in model parameters, atmospheric forcing, and the model's physical mechanics on soil moisture estimates. Several assimilation schemes based on the ensemble Kalman filter(En KF), ensemble Kalman smoother(En KS), and dual En KF(DEn KF) were also compared in this study. The results demonstrate that soil moisture and soil properties can be simultaneously estimated by state-parameter estimation methods, which can provide more accurate estimation of soil moisture than traditional filter methods such as En KF and En KS. The estimation accuracy of the model parameters decreased with increasing error sources. DEn KS outperformed DEn KF in estimating soil moisture in most cases, especially where few observations were available. This study demonstrates that the DEn KS approach is a useful and practical way to improve soil moisture estimation.

Numerical and theoretical investigation on three-dimensional trajectory characteristics of skipping stones

An in-depth study of the complicated trajectory characteristics of skipping stones is carried out in the present work.A three-dimensional numerical simulation validated by acquiring good agreement with experimental results is established.It is devoted to illustrating five different types of motion responses after the stone impacts the water surface in the o-xy plane,including“dive”,“hydroplaning trout”,“hydroplaning skip”,“stable skip”,and“skipping trout”.Then,the lateral deviations are investigated quantitatively based on dimensionless parameter sin(α+β)cosαin the o-yz plane.Steady interval and linear interval are divided for lateral deviation Z1/D and Z2/D based on the values of(α+β)andα,respectively.The results reveal that(1)Z1/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in different(α+β)intervals;(2)Z2/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in differentαintervals;(3)in linear interval,numerical lateral deviations are much larger than the fitting values at pointsβ/α≥4.5,and much smaller than the fitting values at points 2.3≤β/α<4.3.Finally,a theoretical approach is proposed to predict the maximum immersion depth of trailing edge point P.

Influences of Crystal-Field and Interlayer Coupling Interactions on Dynamic Phase Diagrams of a Mixed-Spin(3/2,2)Bilayer System

Influences of crystal-fields （DA and DB ） and interlayer coupling interactions （J3） on dynamic magnetic critical behaviors of a mixed-spin （3//2, 2） bilayer system under an oscillating magnetic field are investigated by the Glauber-type stochastic dynamics based on the mean-field theory. For this purpose, dynamic phase diagrams are constructed in the reduced temperature and magnetic field amplitude plane for the ferromagnetic/ferromagnetic （FM/FM）, antiferromagnetic/ferromagnetic （AFM/FM） and AFM/AFM interactions in detail. We observe that the influences of DA, DB and Ja interactions parameters on the behavior of the dynamic phase diagrams are very much.