Study on numerical simulation to water lowering in an open coal mine digging

In view of the situation of excavation of open coal mine for the underground water disaster,we should carry out simulation studies for the numerical value of the water lowering project and improve the accuracy and the level of the water lowering project.On the basis of the hydrological geological conditions of certain open mine digging,a more reasonable seepage numerical model was built according to MODFLOW.It was simulated in advance that the process of the confined water level descending with the time,and combining with the actual observations to test the correctness of the model.The calculation showed that the results coincided well with the results of actual measurement.Based on this,different water lowering numerical simulations were built for the open coal mine digging.It could be simulated and forecast that the changes of the groundwater level in drainage process within and outside the mine pit,and it was quantitatively assessed that the possible water lowering result of the opencast water drainage process,which provide an important basis for the actual water lowering project and the possible project disposal.     

常顶瓦斯油吸附法脱除微量氯的实验研究

炼油厂将常压塔顶油和减一线油作为重整原料,但由于氯含量过高(30×10-6)无法利用,传统方法是将其中的有机氯转化为无机氯化氢后脱除,但其对加氢催化剂有毒害,采用常顶瓦斯油吸附法可直接脱除微量氯。     

基于3维GIS的热带气旋路径动态演化模拟方法研究

我国是世界上受热带气旋影响最为严重的国家之一,因此研究其机理演变规律将更有利于指导做好防灾减灾工作。本文利用GIS的显示功能,重建和再现热带气旋的登陆路径全过程,在空间格局上,进行时间维的动态演化模拟,为更好地研究热带气旋的演化机理提供一种实用的分析手段。结果表明,该方法对在时空上了解和认识气旋登陆演化全过程的研究具有一定意义。     

基于STC单片机的实验开发平台的设计

介绍了基于STC89C516RD＋单片机的实验开发平台的硬件电路设计、ISP编程、软件开发实例及系统的抗干扰措施.为帮助学生学习单片机技术,同时也为有经验者开发和调试产品打下基础.     

用传输矩阵方法研究多层介质增透膜的透射特性

利用麦克斯韦方程组和边界条件,推导出由高低折射率介质组成周期性的多层增透膜系的传输矩阵,用传输性矩阵求出增透膜系的反射率和透射率表示式,采用Maple语言和数值计算方法得到4层和8层高反射膜系的反射率随入射光波长变化曲线,分析和讨论入射光的入射角对反射率和透射率的影响.得到的结果有利于对多层介质增透膜系结构的理解,为光学仪器镀膜的设计提供了理论依据.     

Approximate third integrals for axisymmetric potentials using local Stäckel fits

We use a set of Stäckel potentials to obtain a local approximation for an effective third integral in axisymmetric systems. We present a study on the feasibility and effectiveness of this approach. We apply it to three trial potentials of various flattenings, corresponding to nearly ellipsoidal, discy and boxy density isophotes. In all three cases, a good fit to the potential requires only a small set of Stäckel potentials, and the associated Stäckel third integral provides a very satisfactory, yet analytically simple, approximation to the trial potentials effective third integral.     

Time evolution of galactic warps in prolate haloes

A recent observation with the Hipparcos satellite and some numerical simulations imply that the interaction between an oblate halo and a disc is inappropriate for the persistence of galactic warps. Following on from this , we have compared the time evolution of galactic warps in a prolate halo with that in an oblate halo. The haloes were approximated as fixed potentials, while the discs were represented by N -body particles. We have found that the warping in the oblate halo continues to wind up, and finally disappears. On the other hand, for the prolate halo model, the precession rate of the outer disc increases when the precession of the outer disc recedes from that of the inner disc, and vice versa. Consequently, the warping in the prolate halo persisted to the end of the simulation by retaining the alignment of the line of nodes of the warped disc. Therefore, our results suggest that prolate haloes could sustain galactic warps. The physical mechanism of the persistence of warp is discussed on the basis of the torque between a halo and a disc and that between the inner and outer regions of the disc.     

Non-linear hydrodynamical evolution of rotating relativistic stars: numerical methods and code tests

We present numerical hydrodynamical evolutions of rapidly rotating relativistic stars, using an axisymmetric, non-linear relativistic hydrodynamics code. We use four different high-resolution shock-capturing (HRSC) finite-difference schemes (based on approximate Riemann solvers) and compare their accuracy in preserving uniformly rotating stationary initial configurations in long-term evolutions. Among these four schemes, we find that the third-order piecewise parabolic method scheme is superior in maintaining the initial rotation law in long-term evolutions, especially near the surface of the star. It is further shown that HRSC schemes are suitable for the evolution of perturbed neutron stars and for the accurate identification (via Fourier transforms) of normal modes of oscillation. This is demonstrated for radial and quadrupolar pulsations in the non-rotating limit, where we find good agreement with frequencies obtained with a linear perturbation code. The code can be used for studying small-amplitude or non-linear pulsations of differentially rotating neutron stars, while our present results serve as testbed computations for three-dimensional general-relativistic evolution codes.     

Galaxy destruction and diffuse light in clusters

Deep images of the Centaurus and Coma clusters reveal two spectacular arcs of diffuse light that stretch for over 100 kpc, yet are just a few kiloparsecs wide. At a surface brightness of m _b ∼27–28 mag arcsec⁻² , the Centaurus arc is the most striking example known of structure in the diffuse light component of a rich galaxy cluster. We use numerical simulations to show that the Centaurus feature can be reproduced by the tidal debris of a spiral galaxy that has been tidally disrupted by the gravitational potential of NGC 4709. The surface brightness and narrow dimensions of the diffuse light suggest that the disc was corotating with its orbital path past pericentre. Features this prominent in clusters will be relatively rare, although at fainter surface brightness levels the diffuse light will reveal a wealth of structure. Deeper imaging surveys may be able to trace this feature for several times its presently observed extent, and somewhere along the tidal debris, a fraction of the original stellar component of the disc will remain bound, but transformed into a faint spheroidal galaxy. It should be possible to confirm the galactic origin of the Centaurus arc by observing planetary nebulae along its length with redshifts close to that of NGC 4709.     

Self-similar shocked accretion of collisional gas with radiative cooling

We describe similarity solutions that characterize the collapse of collisional gas on to scale-free perturbations in an Einstein–de Sitter universe. We consider the effects of radiative cooling and derive self-similar solutions under the assumption that the cooling function is a power law of density and temperature, Λ( T , ρ )∝ ρ ^3/2 T . We use these results to test the ability of smooth particle hydrodynamics (SPH) techniques to follow the collapse and accretion of shocked, rapidly cooling gas in a cosmological context. Our SPH code reproduces the analytical results very well in cases that include or exclude radiative cooling. No substantial deviations from the predicted central mass accretion rates or from the temperature, density and velocity profiles are observed in well-resolved regions inside the shock radius. This test problem lends support to the reliability of SPH techniques to model the complex process of galaxy formation.