颗粒流电磁垂直输运装置物理设计

为满足中国加速器驱动的次临界系统(C-ADS)对于可靠性的要求,计划采用基于螺线管的电磁垂直输运方案,将经过质子束辐照后下落的散裂靶颗粒球再次输运至初始高度。基于解析方法对颗粒流垂直输运装置进行了分析和设计,通过基于螺线管散热、径轴向颗粒流聚散焦效应和互感损耗等方面的考虑,得到了适合于垂直输运颗粒流的螺线管驱动方式和螺线管构型及排布。利用基于本文解析方法的模拟程序,对不同输运管道内径、不同螺线管驱动电流和不同螺线管构型和排布下的颗粒流垂直输运装置进行了模拟,并从中筛选出了该装置的优化设计。模拟表明,采用该优化设计的输运装置可将质量流量为19.6kg/s的颗粒流垂直输运至40m高度,并满足颗粒球出口速度足够大的要求。

南黄海营养盐的垂直分布特性及其垂向输运规律

根据“中韩黄海水循环动力学合作研究”项目１９９６～１９９８年６个航次的调查资料，对南黄海营养盐的垂直分布特征及其垂向输运规律进行了初步探讨。结果表明：（１）南黄海中北部（３４～３７°Ｎ），除冬季营养盐呈垂直均匀分布外，其他季节在远岸海域则呈现明显的层化现象，且在某些海域营养盐等值线呈上凸趋势或呈马鞍形分布，这与生物活动和黄海冷水团及其垂直环流有关；在近岸浅水区，营养盐基本呈垂直均匀分布。（２）南黄海南部（３４°Ｎ以南）：西侧浅水区（水深＜４０ｍ），营养盐基本呈垂直均匀分布且含量很高；东侧深水区，冬、春季营养盐垂直分布均匀且含量较低，夏、秋季时由于来自东海北部的冷水沿坡爬升，营养盐等值线呈极明显的上凸趋势。

Vertical transportation system of solid material for backfilling coal mining technology

For transportation of solid backfill material such as waste and fly ash from the surface to the bottom of the shaft in a fully mechanized backfilling coal backfilling coal mining technology, we developed a new vertical transportation system to transport this type of solid backfill material. Given the demands imposed on safely in feeding this material, we also investigated the structure and basic parameter of this system. For a mine in the Xingtai mining area the results show that: (1) a vertical transportation system should include three main parts, i.e., a feeding borehole, a maintenance chamber and a storage silo; (2) we determined that 486 mm is a suitable diameter for bore holes, the diameter of the storage silo is 6 m and its height 30 m in this vertical transportation system; (3) a conical buffer was developed to absorb the impact during the feeding process. To ensure normal implementation of fully mechanized backfilling coal mining technology and the safety of underground personnel, we propose a series of security technologies for anti-blockage, storage silo cleaning, high pressure air release and aspiration. This vertical transporting system has been applied in one this particular mine, which has fed about 4 million tons solid material with a feeding depth of 350 m and safely exploited 3 million tons of coal.

Modeling vertical heat transport in the wave affected surface layer of the ocean

In considering the vertical heat boundary approximation for the free surface applied. However, due to the existence of the transport problems in the upper ocean, the flat upper and the horizontal homogenous hypothesis are usually wave motion, the application of this approximation may result in some errors to the solar irradiation since it decays quickly in respect to the actual thickness of the water layer below the surface; on the other hand, due to the fluctuation of the water layer depth, it is improper to neglect the effects of the horizontal advection and turbulent diffusion since they also contribute to the vertical heat transport. A new model is constructed in this study to reflect these effects. The corresponding numerical simulations show that the wave motion may remarkably accelerate the vertical heat transferring process and the variation of the temperature in the wave affected layer appears in an oscillating manner.

Study on the Dynamic Characteristics of an Eastward-offshore Mesoscale Vortex along the Meiyu-Baiu Front

The eastward-moving Meiyu-Baiu frontal mesoscale vortices (MBFMVs) appear frequently and often cause heavy rainfall events along their tracks. A move-off-shore MBFMV was selected to enhance our understanding of this type of vortex. Synoptic analyses indicate that the MBFMV is a type of meso-α vortex and mainly occurs in the lower troposphere. A short wave trough near the coastline is highly favorable for the formation, sustainment, and displacement of the MBFMV. Vorticity budgets indicate that at lower levels of the MBFMV, convergence is the dominant factor for the increase of positive vorticity, and at high levels of the MBFMV, the vertical transportation associated with convective activities is the most important factor. The hori-zontal transportation was the main factor decreasing the positive vorticity. The land and sea environments are crucial to the evolution of the MBFMV. The characteristics of the Meiyu-Baiu Front (MBF) are also vital to the variation of the vortex.

Vibration Analysis of Continuous Maglev Guideway Considering the Magnetic Levitation System

The dynamic interaction between moving vehicles and two-span continuous guideway was discussed. With the consideration of the magnetic levitation system, the maglev vehicle/guideway dynamic interaction model was developed. Numerical simulation was performed to understand dynamic characteristics of the guideway used in practice. The results show that vehicle speed, span length and primary frequency of the guideway have an important influence on the dynamic responses of the guideway and there is no distinct trend towards resonance vibration when fl equals 1.0. The definite way is to control the impact coefficient and acceleration of the guideway. The conclusions can serve the design of high speed maglev guideway.

User Preference Survey on Staircase Rotation

Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.

The Characteristics of Turbulence Structure and Transfer over the Middle Area of the Tibetan Plateau

In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport, and the dissipation rates of turbulent kinetic energy, temperature variance, and humidity variance in the middle area of the Tibetan Plateau. The turbulent spectra of wind velocity, potential temperature, and humidity satisfy the-2/3 power law in the high frequency range. Horizontal transportation of heat and water vapor is negligible compared with vertical transportation under strong unstable conditions, and as the stability parameter z/L increases (where z is the observational height, and L is the Monin Obukhov length), horizontal transportation becomes dominant under near-neutral, neutral, and stable conditions. The non-dimensional temperature and humidity variances are 20% less than the temperature and humidity gradient variances. These deficits appear to increase as the absolute stability parameter increases. Moreover, the effects of turbulence transportation and pressure variance exist throughout the entire stability region.

Transient response of Reynolds stress transport to opposition control in turbulent channel flow

The mechanism for turbulence suppression by opposition control developed by Choi is studied via the analysis of Reynolds stress transport in the initial period of control.It is found that the pressure-strain and pressure-diffusion terms first break up the balance in vertical normal Reynolds stress transport,and result in the final global suppression of turbulence intensities.The transient growth in spanwise normal Reynolds stress is also caused by the pressure-strain term.

Interactions Between Exogenous Rare Earth Elements and Phosphorus Leaching in Packed Soil Columns

Rare earth elements （REEs） increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus （P） from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum （La）, neodymium （Nd）, samarium （Sin）, and cerium （Ce）, were investigated with addition of exogenous REEs at various doses to packed soil columns （20 cm deep）. Vertical transfers of REEs and P were relatively small, with transport depths less than 6 cm for most REEs and P. Export of applied REEs in leachate accounted for less that 5% of inputs. The addition of Ce, Nd and Sm to soil columns significantly decreased concentrations of extractable soil P up to a depth of 4 cm, with soil P concentrations unaffected at depths 〉 4 cm. In general, REEs had little effect on the vertical leaching of P in packed soil columns.

A Comparison of Five Different Techniques to Determine Hydraulic Conductivity of a Riparian Soil in North Bavaria, Germany

Soil saturated hydraulic conductivity(K_s) is a predominant input factor when forecasting the vertical transport of contaminants through the soil or when estimating the flood retention capacity of the soil. Displacement of contaminants in the soil over extended periods of time can be attributed mainly to matrix flow, whereas flow through macropores becomes significant under untypically wet conditions, e.g., during spills or rain storms. To obtain matrix conductivities for a soil, the effects of macropores should be excluded.However, the K_s values of a soil profile are unlikely to be reflected solely by pedotransfer tables based on soil texture and bulk density.In this study, we examined five different methods(pedotransfer table, soil core, borehole permeameter, particle-size distribution curve, and instantaneous profile) to determine K_s values for a mercury-contaminated riparian soil for subsequent simulation of longterm mercury displacement toward groundwater. We found that the determined K_s values increased in the following order: borehole permeameter < particle-size distribution curve < pedotransfer table < instantaneous profile < soil core. The instantaneous profile method yielded K_s values of matrix flow, which additionally reflected the structure-related features of K_s values as provided by the soil core method. Despite being labor intensive and requiring expensive field sensors, the instantaneous profile method may provide the best representative in-situ K_s values for the studied site.

The effect of heat transfer on the nonlinear peristaltic transport of a Jeffrey fluid through a finite vertical porous channel

In this paper we analyze the influence of free convection on nonlinear peristaltic transport of a Jeffrey fluid in a finite vertical porous stratum using the Brinkman model. Heat is generated within the fluid by both viscous and Darcy dissipations. The coupled nonlinear governing equations are solved analytically. The expressions for the temperature, the axial velocity, the local wall shear stress and the pressure gradient are obtained. The effects of various physical parameters such as the Jeffrey parameter λ1, the permeability parameter σ and the heat source/sink parameter β are analyzed through graphs, and the results are discussed in detail. It is observed that the velocity field increases with increasing values of the Jeffrey parameter but it decreases with increasing values of the permeability parameter. It is found that the pressure rise increases with decreasing Jeffrey parameter and increasing permeability parameter. We notice that the effect of the permeability parameter a is the strongest on the bolus trapping phenomenon. For λ1 = 0, N =0, the results of the present study reduce to the results of Tripathi [Math. Comput.Modelling 57 （2013） 1270-1283]. Further the effect of viscous and Darcy dissipations is to reduce the rate of heat transfer in the finite vertical porous channel under peristalsis.