三层介质中的磁偶极子的场量分布

磁偶极子在不同介质中的场量分布研究对于感应测井具有重要意义,本文通过有限元程序模拟仿真磁偶极子在三层不同介质中的场量分布。结果表明,磁偶极子离边界越近,涡流减弱,方向沿界面方向流动;电流密度在边界处发生突变,高阻影响大,低阻影响小。

高温空气燃烧技术中换向时间对炉内工况的影响

为了研究在高温空气燃烧技术中换向时间对炉内场量分布和节能效果的影响,在流量控制模式下进行了各种不同切换时间的实验,并采用了3种不同的蓄热体,实验发现升温阶段不进行切换能够解决冷态点火启动困难的问题;实验条件下,分别比较了蓄热速率、炉温分布的均匀性和排烟NO浓度随切换时间的变化,并比较了蜂窝蓄热体和小球蓄热体的蓄热能力。所得结论有一定的应用价值。

铝合金轴固定件热挤压成形的有限体积法模拟研究

由于变形剧烈,复杂铝型材挤压成形有限元模拟会因网格不断重划分而精度欠佳。文中基于可以有效避免网格重划分难题的有限体积法,对铝合金门轴固定产品的热挤压过程进行数值模拟,详细分析挤压成形中各个阶段金属流动情况以及应力、应变、温度、速度等场量的分布变化情况。棒料进入模口至完全流出工作带这段时间是型材挤压最为困难的阶段,材料在工作带处的应力、应变最大,温度最高,因而对模具工作带处造成的磨损也最为严重。进入到最终稳定挤压阶段时挤压方向金属流速计算值与理论挤出速度吻合很好。模拟结果表明所用有限体积法是有效的,可以为铝型材挤压的模具设计与工艺参数的选择提供理论指导。

Modeling Evolution of Weighted Clique Networks

We propose a weighted clique network evolution model, which expands continuously by the addition of a new clique （maximal complete sub-graph） at. each time step. And the cliques in the network overlap with each other. The structural expansion of the weighted clique network is combined with the edges＇ weight and vertices＇ strengths dynamical evolution. The model is based on a weight-driven dynamics and a weights＇ enhancement mechanism combining with the network growth. We study the network properties, which include the distribution of vertices＇ strength and the distribution o~ edges＇ weight, and find that both the distributions follow the scale-free distribution. At the same time, we also find that the relationship between strength and degree of a vertex are linear correlation during the growth of the network. On the basis of mean-field theory, we study the weighted network model and prove that both vertices＇ strength and edges＇ weight of this model follow the scale-free distribution. And we exploit an algorithm to forecast the network dynamics, which can be used to reckon the distributions and the corresponding scaling exponents. Furthermore, we observe that mean-field based theoretic results are consistent with the statistical data of the model, which denotes the theoretical result in this paper is effective.

A Plane-Symmetric Inhomogeneous Cosmological Model of Perfect Fluid Distribution with Electromagnetic Field Ⅰ

A plane-symmetric inhomogeneous cosmological model of perfect fluid distribution with electro-magnetic field is obtained. F12 is the non-vanishing component of electromagnetic field tensor. To get a deterministic solution, we assume the free gravitational field is Petrov type-Ⅱ non-degenerate. Some physical and geometric properties of the model are also discussed.

The Implementation of Radiological Characterization for Reactor Decommissioning

The radiological characterization is to determine the type, the distribution and the radioactivity of the radionuclide in the reactor by investigation of the information, instrumentation detection, sampling analyses and theoretical calculation. It is used for determination of the decommissioning implementation option and radiological protection measure of the workers. After completion of the decommissioning it is used for determination of the site release. The radiological characterization should go through whole decommissioning process, which includes： the collection and review of historical file, the performing calculation of radionuclide inventory in the reactor, in situ measurement, sampling analyses, the review and evaluation of the data obtained and the comparison of calculated result with measured date etc.. The special attention should be paid to the radiological characterization information from the key part of reactor in decommissioning end state. The sampling from the ＂hot spot＂ should not be lost; the number of the sampling should be reasonable based on reliable statistics. The radioactivity density for site release should comply with the guide, standard and regulation of International Atomic Energy Agency and China.

Non-axisymmetric Flow Characteristics in Centrifugal Compressor

The flow field distribution in centrifugal compressor is significantly affected by the non-axisymmetric geometry structure of the volute.The experimental and numerical simulation methods were adopted in this work to study the compressor flow field distribution with different flow conditions.The results show that the pressure distribution in volute is characterized by the circumferential non-uniform phenomenon and the pressure fluctuation on the high static pressure zone propagates reversely to upstream,which results in the non-axisymmetric flow inside the compressor.The non-uniform level of pressure distribution in large flow condition is higher than that in small flow condition,its effect on the upstream flow field is also stronger.Additionally,the non-uniform circumferential pressure distribution in volute brings the non-axisymmetric flow at impeller outlet.In different flow conditions,the circumferential variation of the absolute flow angle at impeller outlet is also different.Meanwhile,the non-axisymmetric flow characteristics in internal impeller can be also reflected by the distribution of the mass flow.The high static pressure region of the volute corresponds to the decrease of mass flow in upstream blade channel,while the low static pressure zone of the volute corresponds to the increase of the mass flow.In small flow condition,the mass flow difference in the blade channel is bigger than that in the large flow condition.

Solutions without a maximum mass limit of the general relativistic field equations for neutron stars

We have investigated the general relativistic field equations for neutron stars.We find that there are solutions for the equilibriummass distribution without a maximum mass limit.The solutions correspond to stars with a void inside their centers.In thesesolutions,the mass density and pressure increase first from zero at the inner radius to a peak and then decrease to zero at the outerradius.With the change of the void boundary,the mass and particle number of the star can approach infinity.Neutron stars withlarge masses can remain stable and do not collapse into black holes.

Field measurement of wind-induced stress on glass facade of a coastal high-rise building

The glass facade of high-rise building in coastal areas is vulnerable under typhoon.The research works in the literature on facade's wind-resistance performance,however,have some limitations to apply to this issue.During typhoon landing,the whole facade will vibrate and deform due to the change of atmosphere,temperature and impacted torrential rain,to result in a quite different strain or stress distribution in the glass facade from those in model test and wind tunnel test.In this paper,the field measurement on glass facade of a coastal high-rise building in Xiamen was performed,the wind pressure on the glass facade was measured and a large number of windinduced stress data were obtained during typhoon landing.The relationship between wind pressure and stress or strain of the glass panel was analyzed and the situation of stress distribution was summarized.

Photo-Detached Electron Flux Distribution in a Gradient Electric Field

This paper investigates the flux distributions of the electron photo-detached from Hion localized in a gradient electric field. In contrast with the photodetachment in the uniform electric field [Phys, Rev. A 40 （1989） 4983], where only two electron trajectories interfere at each given point on a detector, for the photodetachment in a gradient electric field, the electrons waves can travel along multiple paths from the negative ion to a given point on the detector plane, which makes the electron flux distributions on the detector plane become much complex. Using the semi-classicaJ theory, we put forward a formula for calculating the electron flux. Our calculation results suggest that the electron flux distributions on a given detector plane is not only related to the propagation time of the detached electron, but also related to the detached electron＇s energy. With the increase of the detached electron＇s energy, the oscillating region in the electron flux distributions becomes enlarged and the oscillating structure in the flux distributions becomes much more complicated. This study will guide future experiment research on the photodetachment microscopy of the negative ions in the presence of non-uniform external fields.

PIV Measurements of Coolant Flow Field in a Diesel Engine Cylinder Head

This paper presents experimental measurements of coolant flow field in the water jacket of a diesel engine cylinder head. The test was conducted at three different flow rates using a 2-D PIV system. Appropriate tracing particles were selected and delivery device was designed and manufactured before the test. The flow parameters, such as velocity, vorticity and turbulence, were used to analyze the flow field. The effects of vortex which was located between the intake valve and the exhaust valve were discussed. The experimental results showed an asymmetric distribution of velocity in the water jacket. This led to an asymmetric thermal distribution, which would shorten the service life of the cylinder head. The structure optimization to the water jacket of cylinder head was proposed in this paper. The experimental system, especially the 2-D PIV system, is a great help to study the coolant flow structure and analyze cooling mechanism in the diesel engine cylinder head.