面板堆石坝中面板“脱空”的预测和防治

充分模拟坝体材料分区、实际施工、蓄水过程等计算工况,对某水电站高面板堆石坝进行了三维非线性有限元仿真计算。详细地分析了整个大坝的应力变形,对面板与垫层间"脱空"可能和影响机理给予了特别的关注,计算结果显示面板与垫层是否会出现"脱空"现象是可以预测的。计算表明,只要面板不是一次施工完成,面板与垫层间就有可能出现"脱空"现象。提出了面板与垫层间"脱空"的预测和防治方案,当面板分期施工时,建议防治面板与垫层间"脱空"现象发生的几点措施。

Critical load position for cavities beneath CRCP slab under vehicle loading

In order to study the critical load position that causes cavities beneath the continuously reinforced concrete pavement（ CRCP） slab under vehicle loading, the elliptical load is translated into the square load based on the equivalence principle.The CRCP slab is analyzed to determine the cavity position beneath the slab under vehicle loading. The influences of cavity size on the CRCP slab＇s stress and vertical displacement are investigated. The study results showthat the formation of the cavity is unavoidable under traffic loading, and the cavity is located at the edge of the longitudinal crack and the slab corner.The cavity size exerts an obvious influence on the largest horizontal tensile stress and vertical displacement. The slab corner is the critical load position of the CRCP slab. The results can be used to assist the design of CRCP in avoiding cavities beneath slabs subject to vehicle loading.

Deflection and stress of hollow CRCP slab under concentrated vehicle load

Based on the equivalence principle of deflection and stress, the concentrated vehicle load which acts on the center of continuously reinforced concrete pavement （CRCP） is translated into the equivalent half-wave sine load by the Fourier transform. On the basis of this transform and the small deflection theory of elastic thin plates, the deflection and stress formulae of CRCP under the concentrated vehicle load with a hollow foundation are put forward. The sensitivity of parameters is analyzed. The results show that maximum deflection is directly proportional to the concentrated vehicle load and the slab width, and inversely proportional to the lateral bending stiffness and slab thickness. The effects of slab width and thickness are significant with regard to maximum deflection. Maximum stress is directly proportional to the concentrated vehicle load and the slab width as well as inversely proportional to slab thickness. The effect of slab thickness is significant with regard to maximum stress. According to the calculation results, the most effective measure to reduce maximum deflection and stress is to increase slab thickness.

Thermodynamics of removing impurities from crude lead by vacuum distillation refining

A novel technique was developed to remove impurities from crude lead by vacuum distillation.The thermodynamics on vacuum distillation refining process of crude lead was studied by means of saturated vapor pressure of main components of crude lead,separation coefficients and vapor-liquid equilibrium composition of Pb-i（i stands for an impurity） system at different temperatures.The behaviors of impurities in the vacuum distillation refining process were investigated.The results show that the vacuum distillation should be taken to obtain lead from crude lead,in which Zn,As and partial Sb are volatilized at lower temperature of 923-1023 K.Lead is distilled from the residue containing Cu,Sn,Ag and Bi at higher temperature of 1323-1423 K,but the impurity Bi is also volatilized along with lead and cannot be separated from lead.

A STUDY OF THE PROPERTIES OF S25C-SUS405 STEEL JOINTS BY VAOUUM DIFFUSION WELDING

In this paper, the properties of S25C-SUS405 steel joints by vacuum diffusion welding are discussed, and the specific deformation, tensile strength and hardness of the joints made of those two kinds of steel are introduced. Through metallographic examination and microanalysis, it can be observed that at the weld interface of the joints there is a decarbonized layer on the S25C steel side and a carburized layer on the SUS405 steel side. This is the main cause giving rise to the heterogeneity of microstructure distribution and the nonuniformity of hardness distribution in weldment. In addition, with the help of electronic probe microanalysis the element distribution, such as carbon and chrome, is reported in this paper.

Pt nanoparticles encapsulated on V_(2)O_(5)nanosheets carriers as efficient catalysts for promoted aerobic oxidative desulfurization performance

Platinum group metals(PGMs)usually exhibit promising aerobic catalytic abilities,providing a green and feasible oxidative desulfurization method.However,often,the PGM nanoparticles(NPs)get leached,and the catalysts are deactivated.In this work,Pt NPs with particle sizes of approximately 4–5 nm were encapsulated effectively and uniformly on the surface of vanadium pentoxide(V2O5)nanosheets(with thicknesses of approximately six atomic layers)through strong metal-support interactions.The synthesized catalysts promote catalytic aerobic oxidation reactions,realizing deep desulfurization(99.1%,<5μg g^(–1))under atmospheric pressure and 110℃reaction temperature.Remarkable degrees of sulfur removal could be achieved for oils with different initial S-concentrations and substrates.Additionally,the as-prepared catalysts could be recycled for reuse at least seven times.

Controllable Subspaces of Open Quantum Dynamical Systems

This paper discusses the concept of controllable subspace for open quantum dynamical systems. It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perform open-loop coherent control on open quantum systems will allow decoherence-free subspaces to be controllable. This is in contrast to the observation that open quantum dynamical systems are not open-loop controllable. To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subspaces can be useful for quantum computation.

Entropy Exchange and Entanglement in Superconducting Charge Qubit Inside a Resonant Cavity with Intrinsic Decoherence

By considering the intrinsic decoherence effect, we investigate the entropy exchange and entanglement in the interacting system of a superconducting charge qubit coupled to a single-mode optical cavity. We found that although the intrinsic decoherence leads to an irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator, and has an apparently influence on the partial entropies of the two-component subsystems, it dose not destroy entropy exchange behavior. In addition, the lower bound of the concurrence, as the measure of entanglement of the coupling system, is calculated. It is shown that the evolution of entanglement is sensitive to the change of the intrinsic decoherence.

Modeling investigation of geometric size effect on pervaporation dehydration through scaled-up hollow fiber NaA zeolite membranes

A mass transfer model in consideration of multi-layer resistances through NaA zeolite membrane and lumen pressure drop in the permeate side was developed to describe pervaporation dehydration through scaled-up hollow fiber supported NaA zeolite membrane. It was found that the transfer resistance in the lumen of the permeate side is strongly related with geometric size of hollow fiber zeolite membrane, which could not he neglected. The effect of geometric size on pervaporation dehydration could be more significant under higher vacuum pressure in the permeate side. The transfer resistance in the lumen increases with the hollow fiber length but decreases with lumen diameter. The geometric structure could be optimized in terms of the ratio of lumen diameter to membrane length. A critical value of d1/L （Rc） to achieve high permeation flux was empirically correlated with extraction pressure in the permeate side. Typically, for a hollow fiber supported NaA zeolite membrane with length of 0.40 m, the lumen diameter should be larger than 2.0 mm under the extraction pressure of 1500 Pa.

Outgassing from internal adhesive joints of vacuum devices

Kinetics of the formation of residual atmosphere in vacuum devices with internal adhesive joints and the application of the mass spectral and chromatographic methods to measure the specific outgassing rate of volatile compounds from the cured adhesives are considered in this paper.The outgassing comparison data for the various types of adhesives are given and the effectiveness of the outgassing of adhesive joints is demonstrated.The possible options to provide vacuum in the various devices are considered.At moderate requirements to the residual pressure(about10-2Pa),it is enough to degass the adhesive joints during a few hours.It is much more difficult to provide vacuum in devices with internal adhesive joints at the level of about10-4Pa.This requires the use of the built-in getter and the high temperature degassing.It is expedient to provide deep vacuum(10-5-10-4Pa)in the rare-used or once-used devices by short(a few minutes)activation the built-in getters before operating the vacuum devices.This allows to remove the main residual gas hydrocarbons component from the vacuum house and provide the necessary level of vacuum for a certain interval of time.

Activation of small molecules over praseodymium-doped ceria

Praseodymium can modify the properties of ceria (CeO2), changing the electronic structure, reducibility and catalytic behavior. Oxygen vacancies in the ceria-based samples can activate C–O and C–H bonds of small molecules such as CO2 and propane. Partially reduced Pr/CeO2-x can selectively activate C–H of propane, giving a propylene selectivity of ca. 75% at a propane conversion of 5% to 10%. Excess reduction of Pr/CeO2-x induces coking reactions during propane dehydrogenation, resulting in fast catalyst deactivation.

Stability of Decoherence-Free Subspaces under Stochastic Phase Fluctuations

We study the stability of decoherence-free subspaces under stochastic phase fluctuations by analytically and numerically evaluating the fidelity of the corresponding decoherence-free subspace bases with stochastic phase fluctuations under the evolution of environment. The environment is modeled by a bath of oscillators with infinite degrees of freedom and the register-bath coupling is chosen to be a general dissipation-decoherence form. It is found that the decoherence-free subspaces take on good stability in the case of small dissipation and small phase fluctuations.

Vortex-Induced Vibration of Two Parallel Risers:Experimental Test and Numerical Simulation

The vortex-induced vibration of two identical rigidly mounted risers in a parallel arrangement was studied using Ansys-CFX and model tests.The vortex shedding and force were recorded to determine the effect of spacing on the two-degree-of-freedom oscillation of the risers.CFX was used to study the single riser and two parallel risers in 2–8D spacing considering the coupling effect.Because of the limited width of water channel,only three different riser spacings,2D,3D,and 4D,were tested to validate the characteristics of the two parallel risers by comparing to the numerical simulation.The results indicate that the lift force changes significantly with the increase in spacing,and in the case of 3D spacing,the lift force of the two parallel risers reaches the maximum.The vortex shedding of the risers in 3D spacing shows that a variable velocity field with the same frequency as the vortex shedding is generated in the overlapped area,thus equalizing the period of drag force to that of lift force.It can be concluded that the interaction between the two parallel risers is significant when the risers are brought to a small distance between them because the trajectory of riser changes from oval to curve 8 as the spacing is increased.The phase difference of lift force between the two risers is also different as the spacing changes.

Experimental Investigation on Simultaneous Dry Blanching and Drying of Mushroom Slices Using Microwave Enhanced Hot Air Heating System

The study evaluated the feasibility of using microwave enhanced hot air heating system for simultaneous dry blanching and dehydration of mushroom slices. The technology involves application of microwave energy at the beginning of dehydration process to inactivate enzymes as well as to remove a certain amount of moisture at the same time and then followed by hot air drying to complete the process. The study investigated effects of different processing parameters, i.e., microwave power level and exposure time on dehydration and quality characteristics of mushroom slices. Mushroom slices were pretreated with different microwave power levels of 240, 360 and 480 W for 1, 3 and 5 min before the hot air-drying. The optimum range of the microwave power level and pretreatment time was found to be 360 W, 3 min and 360 W, 1 min in obtaining the maximum and minimum levels of response parameters.

Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO_(2)(110)

The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this work we have investigated the role of bridge bonded oxygen vacancy(O_(v))in methyl groups and carbon monoxide(CO)adsorption on rutile TiO_(2)(110)(R-TiO_(2)(110))with the temperature programmed desorption technique.The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen(O_(b)),and CO molecules on the five coordinate Ti^(4+)sites(Ti_(5c))as the Ovconcentration changes,suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO_(2)(110).

Removal of VOCs from Sudden Polluted Raw Water by Air Stripping

Volatile organic compounds （VOCs） are widely used in various industrial processes and generate water pollutions. VOCs removal from raw water is an important task for waterworks to guarantee drinking water security. The removal of VOCs such as chlorobenzene （CB） and ethylbenzene （EB） from raw water by air stripping was investigated under various conditions, inciuding the variation of temperature （5-30~C）, pH （3.5-10.5）, and air/water ratio （10-60）. The air stripping removal efficiency of VOCs decreased with VOCs concentration declining in water. And Henry＇s law constant was demonstrated as an indicator of the estimation of VOCs removal efficiency for air stripping. The effects of temperature and the ratio of air and water were found to play a great role in VOCs removal, but the effect of pH seemed to be negligible. This study demonstrates that air stripping provides a promising opportunity in removing VOCs in drinking water treatment, especially for the relatively high concentration of VOCs.

Kinetics of Wet Air Oxidation of Wastewater from Natural Fiber Web Desizing

This work described the application of wet air oxidation (WAO) to the treatment of desizing wastewater from natural fiber processing. A two-liter autoclave batch reactor was used for the experiments. The range of operating temperature examined was between 150 and 290℃, and partial pressure of oxygen ranged from 0.375 to 2.25 MPa standardized at 25℃. Variations in Chemical Oxygen Demand(COD) and Total Organic Carbon(TOC) were monitored during each experiment and used to assess the performance of the process. Experimental results showed that WAO can be an efficient method for the treatment of desizing wastewater. Furthermore, Catalytic Wet Air Oxidation (CWAO) was applied to reduce the reaction temperature and pressure in WAO process. A higher COD removal ratio was achieved under more mild reaction condition with the aid of CWAO. A mathematical model was also proposed to simulate the WAO process of desizing wastewater, in which three distinct kinetics steps were considered to describe the degradation of starch. The model simulations were in well agreement with the experimental data.

Commercial Test of Two Diesel Demulsifiers

PetroChina Lanzhou Petrochemical Company conducted commercial tests for application of two types of diesel demulsifiers, the HPL-2 and GX-02 demulsifiers, in order to solve the emulsion problem arising from caustic washing of straight-run diesel fraction obtained from atmospheric and vacuum distillation unit at the Lanzhou refinery. After addition of each demulsifier into the diesel fraction the oil content in caustic residue was apparently decreased, and discharge of waste caustic was reduced, resulting in the elimination of emulsification and a significant increase of economic benefits. When 70 ppm of the HPL-2 demulsifier was added to diesel fraction, the oil content in waste caustic exiting the second-stage caustic wash settling tank was reduced to 2.45% from 7.90 %, whereas this value was reduced to 2.81% from 5.96% with addition of the GX-02 demulsifier.

Simulations of the Allowable Load Current of the Overhead Lines in the Latvian Power Network

This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.

Entanglement Dynamics of Multipartite Systems Under Decoherence from a Spin Environment

The entanglement evolution of multipartite quantum states under a spin environment is analyzed. Due to interaction, the extent to which the entanglement vanishes depends not only on the size of system and the structure of quantum states, but also on the exchange couplings with environment. The decoherence-free subspaces have been identified by using the linear entropy.