热-水力-力学-传质耦合过程模型及工程土障数值模拟

提出了一个非饱和多孔介质中的热 -水力 -力学 -传质耦合过程模型。利用文献 [1]中提出的热 -水力 -力学本构模型 ,对工程土障系统进行数值模拟。数值模拟结果显示了环境条件对废物场中的热量产生和传输过程对工程土障中水力 -力学行为的影响以及可能在工程土障中产生塑性应变 ,导致土障破坏。污染物浓度分布的数值结果显示了温度与降水过程对污染物随地下水向土障周边自然环境渗透的倾向。

膨胀性非饱和土水力和力学性质的弹塑性模拟

Alonso等人提出的非饱和土弹塑性本构模型(BBM),不能用于预测膨胀性非饱和土的力学性质。现有的膨胀性非饱和土的弹塑性模型(BExM),其微观参数及微宏观变形的转换关系确定非常困难。从宏观角度,在已有的非膨胀性非饱和土水力特性和力学性质耦合的弹塑性本构模型的基础上,发展和建立了一个可预测非饱和膨胀土的水力特性和力学特性的弹塑性本构模型。模型引入不同形状的等孔隙比线与屈服线,并考虑了变形对土水特性的影响。对已公开发表的非饱和膨胀土的试验结果进行预测,包括常净应力的吸湿试验,吸力不变的等向压缩试验及三轴剪切试验。预测结果表明该模型能够定量的描述膨胀性非饱和土的水力和力学特性。

山前小流域水文—水力学耦合洪水预报研究

为了提高受人类活动影响显著的小流域洪水预报精度,以浙江省杭州市东苕溪流域为研究对象,分别以半分布式新安江模型、平原区水文模型、分洪区水动力模型以及一维河网模型模拟山区、平原区、分洪区以及河道的洪水过程,在卡尔曼滤波实时校正技术的支持下,建立流域水文—水力学耦合预报模型。通过对1996年以来瓶窑站典型洪水进行率定和验证,表明该模型符合东苕溪预报的精度要求。在2012年"海葵"台风的实时预报应用中,该模型发挥了辅助决策的作用,可作为后期防汛决策的参考。

含离子类溶质黏土的C-H-M本构模型

在水力-力学本构模型基础上,采用化学软化公式引入孔隙水中含盐、碱类等离子类溶质对土体前期固结压力的影响,得到土体的化学-水力-力学耦合本构模型(C-H-M模型).根据试验结果对化学软化公式的参数进行数值拟合,通过算例验证了C-H-M本构模型的有效性.

A Molecular Thermodynamic Model for Interfacial Tension in Surfactant-Oil-Water System

An interfacial equation of state based on perturbation theory for surfactant-oil-water system has been developed. By combining the interfacial equation of state with Boudh-Hir and Mansoori's model, a molecular ther-modynamic model has been proposed. The interfacial tension of surfactant-oil-water systems can be calculated from the surface tensions of pure oil and water by this model. The interfacial tension data for sodium dodecyl sulphate-heptane-water system, polyoxyethylene n-octylphenol-heptane-water system and hexadecyl trimethyl ammonium bromide-heptane-water system have been correlated. By using the adjustable parameters obtained, the interfacial tensions of these systems at other temperatures have been predicted. Both the correlated and the predicted values are satisfactory.

Study on Hydraulic System Efficiency of Heaving-Buoy Wave Energy Converter

The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy WEC.We derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy accumulator.The model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic resistance.We also studied the relationship between the efficiency and the initial conditions.Finally,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.

Theoretical analysis on water-inrush mechanism of concealed collapse pillars in floor

In order to study the water-inrush mechanism of concealed collapse pillars from the mechanical view, a mechanical model for water-inrush of collapse pillars has been established based on thick plate theory of elastic mechanics in this paper.By solving this model the deformation of water-resistant rock strata under the action of water pressure and the expression of critical water pressure for collapse pillar waterinrush have been obtained The research results indicate that：the boundary conditions and strength of water-resistant strata play important roles in influencing water-inrush of collapse pillars.The critical water-inrush pressure is determined by both relative thickness and absolute thickness of water-resistant strata.

Research status of soil frost-heave theory and frost-heave prediction models

Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and those achievements recently made by scholars. In this paper, we also discus researching achievements of the soil-prediction model during the past 40 years, including the water-dynamics model, the rigid-ice model, the segregation-potential model, and the thermo-dynamic model. This summary and discussion will enable readers to understand the latest direction of research; it also summarizes the development of frost-heave prediction models and their advantages and shortcomings.

Ground movement mechanism in tectonic stress metal mines with steep structure planes

When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.

Thermal dehydration kinetic mechanism of Mn_(1.8)Co_(0.1)Mg_(0.1)P_2O_7·2H_2O using Málek's equations and thermodynamic functions determination

Mn1.8Co0.1Mg0.1P2O7·2H2O was synthesized via hydrothermal method and the thermal dehydration product was confirmed to be Mn1.8Co0.1Mg0.1P2O7.The thermogravimetry/differential thermogravimetry/differential thermal analysis,Fourier transform infrared,atomic absorption spectrophotometry,X-ray diffraction and scanning electron microscopy techniques were employed for sample characterization.Non-isothermal kinetics was studied under air atmosphere at four heating rates and the single thermal dehydration process was observed.Iterative Kissinger-Akahira-Sunose equation was used to calculate the apparent activation energy Eαvalues.Dehydration process was confirmed to be a single-step kinetic process with the unique kinetic triplets.Málek’s equations were used to determine the kinetic model f（α）and pre-exponential factor A.？esták-Berggren model was suggested to be the mechanism function for the dehydration process.The best fit led to the kinetic triplets of Eα=（79.97±6.51）k J/mol,ln A=16.83 and f（α）=α^0.520（1-α）^1.255（αis the extent of conversion）.The thermodynamic functions of activation were calculated using activated complex theory together with A value.

The Application of Ecosystem Dynamic Model in Xiamen Bay

This paper is to establish a nitrogen and phosphorus nutrients cycle-based numerical model of ecological dynamics for Xiamen Bay on the basis of the existing three-dimensional barocline hydrodynamic model. The calculation results show that the estuarine district of Jiulongjiang estuary has the highest inorganic nitrogen concentration followed by the West Harbor, which demonstrates that Jiulongjiang River is the main input source of inorganic nitrogen in Xiamen Bay. The West Harbor has relatively high concentration of nutrients caused by the huge land pollution emission and its own poor water exchange capacity; while the distribution rules of phytoplankton biomass correspond with those of phosphates, demonstrating Xiamen Bay＇s phytoplankton controlled by phosphorus; the haloplankton biomass differs slightly, presenting the gradual reduction from the interior part to the exterior part of the bay.

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

Estimation of the Hydrodynamic Regime of the Water Movement under the Influence of the Atmospheric Processes in the Bering Sea and the Sea of Okhotsk

The given investigation presents the results of estimating the water circulation in the water area of the Bering Sea and the Sea of Okhotsks, considering the influence of various types of the atmospheric processes. To solve the given problem it is used a hydrodynamic model calculating the integral functions of the flow from the surface to the bottom. By results of calculations, the maps of the integral water circulation were built for the following types of atmospheric circulation： ＂north-western＂ and ＂okhotsk-aleutian＂. In accordance with the performed calculations for the water area being studied, the hydrodynamic structures are distinguished both non-depending and depending on the type of the atmospheric circulation. The non-depending structures are characterized by the cyclonic activity in the Bering Sea and the Sea of Okhotsk in whole. Hydrodynamic structures depending on types of the atmospheric circulation have their peculiarities in the spatial-temporal distribution.

Hydrodynamics of Liquid Flow in the Model of Theoretical Stage with Perfect Displacement

For the cyclic process of mass transfer in tray columns there are considered the hydrodynamic models of liquid flow during steam supply and during overflow of liquid from tray to tray. During steam supply, the hydrodynamic model is determined as perfect displacement model, and during liquid overflow, it is described as cell model. There were received the characteristics of liquid flow as follows： average residence time of liquid, degree of dispersion around the mean on the tray, number of perfect mixing cells depending on multiplication factor of exchange of liquid delay. In Y-X coordinates there is depicted a work line and theoretical stage of perfect displacement model. There were considered the conditions of mutual transfer of theoretical stage and theoretical stage with perfect displacement. The advantages of the mass transfer cyclic process to the stationary one arc stated.

Computation of the Viscous Hydrodynamic Forces on a KVLCC2 Model Moving Obliquely in Shallow Water

The viscous hydrodynamic force and moment on ships moving obliquely in shallow water are important for ship navigation safety.In the paper,the viscous flow field around a KVLCC2 model moving obliquely in shallow water is simulated and the hydrodynamic drag,lateral force and yaw moment acting on the hull are obtained by a general purpose computational fluid dynamics(CFD) package FLUENT with shear-stress transport(SST) k—ωturbulence model.The numerical computation is performed at different drift angels and water depths.The numerical results are compared with experimental results,and a good agreement is demonstrated.