岩石裂隙中非恒定渗流与变形耦合作用的DDA方法

由于渗流作用,会在岩石裂隙中形成非稳定流,非稳定流作为裂隙表面荷载会使岩体产生变形,变形又会影响岩土结构的渗流特性,从而产生渗流和变形耦合的作用.根据最小能量原理构造出单元DDA(不连续变形分析)瞬时平衡方程.编制了基于DDA的岩石裂隙中稳定渗流和不稳定渗流压力水头的有限单元计算程序,通过对实验结果与计算结果的比较,验证了计算程序所使用的数学模型的可靠性.地下水是影响边坡受力变形及稳定性的一个重要因素.通过对某隧洞破坏过程的模拟,用这种渗流-变形耦合DDA法研究了地下水对裂隙边坡稳定性的影响.模拟结果与实际发生的结果一致,验证了本文方法的可靠性.     

混编货车通过中小跨度桥梁时车桥振动分析

运用基于蠕滑理论的车桥耦合振动空间分析程序，分析了混编货车通过铁路上标准32m跨径预应力混凝土简支梁时的车桥振动特征．从列车在不同加载位置对桥梁的作用以及桥梁对车辆的反作用的角度出发，结合车桥的动力特性，揭示了混编货车过桥时，一般桥梁振动响应较大、轻车容易发生脱轨事故的机理——混编货车由于轴重差别显著，对桥梁产生周期性的大幅值的强迫荷载，导致桥梁振动剧烈，而桥梁的振动加剧又对轻车产生强烈的反作用．     

Algorithms for improving accuracy of spray simulation

Fuel spray is the pivotal process of direct injection engine combustion.The accuracy of spray simula- tion determines the reliability of combustion calculation.However,the traditional techniques of spray simulation in KIVA and commercial CFD codes are very susceptible to grid resolution.As a conse- quence,predicted engine performance and emission can depend on the computational mesh.The two main causes of this problem are the droplet collision algorithm and coupling between gas and liquid phases.In order to improve the accuracy of spray simulation,the original KIVA code is modified using the cross mesh droplet collision(CMC)algorithm and gas phase velocity interpolation algorithm.In the constant volume apparatus and D.I.diesel engine,the improvements of the modified KIVA code in spray simulation accuracy are checked from spray structure,predicted average drop size and spray tip penetration,respectively.The results show a dramatic decrease in grid dependency.With these changes,the distorted phenomenon of spray structure is vanished.The uncertainty in predicted aver- age drop size is reduced from 30 to 5μm in constant volume apparatus calculation,and the uncertainty is further reduced to 2μm in an engine simulation.The predicted spray tip penetrations in engine simulation also have better consistency in medium and fine meshes.     

异桥联(μ-Cl和μ-OCH_3)双核铜(II)配合物磁偶合体系中桥联原子的轨道互补效应

采用密度泛函结合对称性破损(DFT-BS)方法,研究了异桥联(μ-Cl和μ-OCH3)双核铜(II)配合物磁偶合体系中桥联原子轨道相互作用。计算结果表明,两个桥联配体原子轨道对反铁磁性偶合,表现为轨道互补效应。这种互补效应不仅表现在磁偶合作用的一致性,而且表现在对磁偶合贡献的加合性。分子轨道和自旋集居数分析都很好解释了计算的结果。     

附加质量模型在渡槽抗震计算中的适用性研究

针对南水北调中线某大型渡槽结构,分别基于流固耦合理论和附加质量方法建立了数值分析模型,对其自振频率和地震响应进行了分析。结果表明,两种模型的自振频率比较接近;附加质量模型的地震响应要大于流固耦合模型。因此,在渡槽抗震研究中,采用较简单的附加质量模型代替复杂的流固耦合模型考虑水体的影响是偏于安全的,适用于渡槽结构抗震的定性分析。     

联用技术在砷形态分析中的应用进展

综述了高效液相色谱与原子吸收光谱、原子发射光谱、原子荧光光谱和电感耦合等离子质谱等联用技术以及毛细管电泳原子荧光光谱联用技术在砷形态分析中的应用研究新进展,并对砷形态分析中的样品贮存、前处理技术进行了总结和评述。     

碳化硼的改性及其在有机硅树脂中的应用

为了提高碳化硼粉体与有机硅树脂的相容性，采用硅烷偶联剂KH-550对碳化硼粉体进行了表面改性，研究了表面改性的工艺条件及改性的碳化硼粉体对有机硅涂层性能的影响。通过接触角的测定，确定了改性工艺。偶联剂用量为碳化硼粉体质量的5.0％，改性温度为80℃，改性时间为3h。红外光谱分析表明，偶联剂在粉体表面产生了有效吸附，改变了粉体的表面性质。涂层机械性能、扫描电镜和交流阻抗测试的结果表明，改性的碳化硼粉体与有机硅树脂具有很好的相容性。     

Control of coupling among three major factors for formation of high-efficiency gas reservoir——A case study on the oolitic beach gas reservoir in Feixianguan Formation in the northeast Sichuan Basin

Through a case study of the high-efficiency gas reservoir in Feixianguan Formation in the northeast Sichuan Basin, quantitative and semi-quantitative analyses of key elements such as hydrocarbon generation, migration and accumulation, and reservoir evolution as well as their interplay in the critical moment of reservoir formation controlled by the energy field were carried out, by means of numerical modeling of the energy field. It was found that the climax time for Permian hydrocarbon generation was Late Triassic-Early Jurassic and accumulation of oil and gas has resulted in large-scale paleoreservoirs in paleostructural traps in Feixianguan Formation, a process facilitated by fractures connecting the sources. The paleoreservoirs have been turned into high-efficiency gas kitchens due to pyrolysis, which resulted from deep burial at a temperature of 170―210 ℃ as induced by tremendously thick sedimentation in the foreland basin of Daba Mountain in Late Jurassic-Cretaceous period. Meanwhile, abundant acid gas like H2S produced from thermo-chemical sulfate reduction (TSR) at high temperatures leads to extensive dissolution of dolostone in the paleoreservoirs, which may in turn result in modification of the reservoirs and preservation of the reservoir rock porosity. The present distribution of gas reservoirs was ultimately determined in the processes of adjustment, cooling and decompression of the paleoreservoirs resulting from intense deformation in the front of Daba Mountain during the Himalayan orogeny.     

Information flow among neural networks with Bayesian estimation

Estimating the interaction among neural networks is an interesting issue in neuroscience. Some methods have been proposed to estimate the coupling strength among neural networks; however, few estimations of the coupling direction (information flow) among neural networks have been attempted. It is known that Bayesian estimator is based on a priori knowledge and a probability of event occurrence. In this paper, a new method is proposed to estimate coupling directions among neural networks with conditional mutual information that is estimated by Bayesian estimation. First, this method is applied to analyze the simulated EEG series generated by a nonlinear lumped-parameter model. In comparison with the conditional mutual information with Shannon entropy, it is found that this method is more successful in estimating the coupling direction, and is insensitive to the length of EEG series. Therefore, this method is suitable to analyze a short time series in practice. Second, we demonstrate how this method can be applied to the analysis of human intracranial epileptic electroencephalogram (EEG) recordings, and to indicate the coupling directions among neural networks. Therefore, this method helps to elucidate the epileptic focus localization.     

基于快响应CAD方法的高速电磁开关阀设计

针对高速电磁开关阀电，磁，机，液的耦合特性及铁磁材料磁化过程的非线性，提出了一种新的耦合计算模型，其中非线性电磁子模型用等效电路和内插函数重新表示，并用迭代方法进行同步计算，可较好地解决各子系统之间的耦合问题和非线性问题，用该方法预测的高速电磁开关阀的性能与实验结果吻合良好，实现了高速电磁驱动元件的快响应设计。