吉黑高速公路孙吴至黑河段地质灾害调查与评价

通过对吉黑高速公路孙吴至黑河段不良地质现象的调查与分析,对于该段可能诱发的地质灾害进行了评价,确定了该路段存在的主要地质问题。     

Numerical simulation of flow phenomena and optimum operation of tundish

1　INTRODUCTIONDuringthecourseofcontinuouscastingsteel,theflowofliquidsteelintundishwasafairlycomplexprocesscontainingmomentumtransfer,masstransfer,energytransferandphase changeofmultiphasecomponents .Ac cordingtoRefs.[1,2 ],someinfluencingfactorsincastingsteelwerefound ,includingthecompositionofliquidsteel,thetechnicalparametersoftundishandre oxidationofmoltenmetal.Theprocesswouldaffectdirectlysurfacedefectsandinternalstructureformationofthecastingsteelproductsaswellastherealizationofhig…     

SLA中僵化现象的研究及其对英语口语教学的启示（英文）

了解非英语专业学生僵化现象的总体情况及僵化现象是否是暂时性的以及造成僵化现象的原因,分析和总结了非英语专业学生的口语僵化的程度,提高对大学生口语水平进行实验研究.实验数据表明,实验组学生在接受特殊训练后所犯的错误明显少于控制组学生;大学生的口语水平通过训练是能够得到提高的,僵化现象只是暂时性的,不是长久的,这种现象是可以被打破的.     

Construction and application of fractal interpolation surfaces

Fractal geometry has unique advantages for a broad class of modeling problems, including natural objects and patterns. This paper presents an approach to the construction of fractal surfaces by triangulation. After introducing the notion of iterated function systems (IFSs), we prove theoretically that the attractors of this construction are continuous fractal interpolation surfaces (FISs). Two fast, parallel, and iterative algorithms are also provided. Several experiments in natural phenomena simulation verify that this method is suitable for generating complex 3D shapes with self-similar patterns.Project supported by the National Natural Science of China     

汉语词性标注方法的研究

1 引言自然语言中,表达意义的符号(词)往往在各个层面上有歧义。在句法层面上,一个词可以兼好几种词性;在语义层面上,一个词可能有多个义项。词性歧义是由语言中的兼类词,即具有不止一个词性特征的词所引起的,只有在一定的上下文语境关系中,词所表现     

Random Constraint Satisfaction: A More Accurate Picture

In the last few years there has been a great amount of interest in Random Constraint Satisfaction Problems, both from an experimental and a theoretical point of view. Quite intriguingly, experimental results with various models for generating random CSP instances suggest that the probability of such problems having a solution exhibits a threshold–like behavior. In this spirit, some preliminary theoretical work has been done in analyzing these models asymptotically, i.e., as the number of variables grows. In this paper we prove that, contrary to beliefs based on experimental evidence, the models commonly used for generating random CSP instances do not have an asymptotic threshold. In particular, we prove that asymptotically almost all instances they generate are overconstrained, suffering from trivial, local inconsistencies. To complement this result we present an alternative, single–parameter model for generating random CSP instances and prove that, unlike current models, it exhibits non–trivial asymptotic behavior. Moreover, for this new model we derive explicit bounds for the narrow region within which the probability of having a solution changes dramatically.     

Modeling and animating turbulent gaseous phenomena using spectral synthesis

This paper presents a new spectral synthesis method, motivated by the spectral turbulence theory, for visual modeling and the realistic and computer-effective animation of turbulent gaseous motion in 2-D and 3-D, which avoids the computational costs of direct simulation. Animation of gases is achieved through a phase shift in the frequency domain according to Kolmogorov's exponential law. The parameters of the turbulence model are intuitive, enabling animaters and designers to become familiar with them quickly. Owing to the method's computational effectiveness, an interactive, (quasi-)real-time, parallelized version, which provides the fast feedack needed to easily adjust the model's parameters, could be implemented.     

Hybrid molecular dynamics-continuum simulation for nano/mesoscale channel flows

The present study deals with multiscale simulation of the fluid flows in nano/mesoscale channels. A hybrid molecular dynamics (MD)-continuum simulation with the principle of crude constrained Lagrangian dynamics for data exchange between continuum and MD regions is performed to resolve the Couette and Poiseuille flows. Unlike the smaller channel heights, H < 50σ (σ is the molecular length scale, σ ≈ 0.34 nm for liquid Ar), considered in the previous works, this study deals with nano/mesoscale channels with height falling into the range of 44σ ≤ H ≤ 400σ, i.e., O(10)–O(10²) nm. The major concerns are: (1) to alleviate statistic fluctuations so as to improve convergence characteristics of the hybrid simulation—a novel treatment for evaluation of force exerted on individual particle is proposed and its effectiveness is demonstrated; (2) to explore the appropriate sizes of the pure MD region and the overlap region for hybrid MD-continuum simulations—the results disclosed that, the pure MD region of at least 12σ and the overlap region of the height 10σ have to be used in this class of hybrid MD-continuum simulations; and (3) to investigate the influences of channel height on the predictions of the flow field and the slip length—a slip length correlation is formulated and the effects of channel size on the flow field and the slip length are discussed. An erratum to this article can be found at     

计及Casimir效应时旋转式NEMS致动器的动态稳定性研究

分析了Casimir力对旋转式纳电子机械(NEMS)致动器动态稳定性的影响.计及Casimir效应时,旋转式致动器失稳时的临界倾角和临界电压和结构的几何尺寸有关.外加电压为零时,导出了旋转式致动器在Casimir力作用下发生吸合的临界特征几何尺寸.给出了旋转式致动器的无量纲化运动控制方程,并对它作了定性分析.定性分析表明:该运动方程相应的自治系统在相平面上的平衡点包括中心点、稳定的焦点和不稳定的鞍点;相图呈现周期轨道、同宿轨道以及异宿轨道.另外系统还存在分叉现象.     

用MATLAB实现电磁波与目标作用的动态可视化

给出了一种实现电磁波与目标相互作用现象可视化的方法。首先用时域有限差分法在数值上模拟电磁波与目标相互作用过程,获取电磁场数据,然后利用MATLAB软件的科学计算可视化功能,将原始数据转换为动态图像。从而能够观察到电磁波传播、穿透、散射和吸收等现象,为直观地了解电磁波与目标相互作用的过程提供了一个有效的手段。