A characterization of some geometries of Lie type

For geometries associated with permutation representations of the groups of Lie type E ₆, E ₇, E ₈ on certain maximal parabolic subgroups (e.g. the stabilizers of root subgroups), axiom systems are given that characterize them in terms of points and lines.     

高层建筑动态风干扰的瞬态风压积分法研究

提出通过在风洞试验中多通道测量刚性模型表面瞬态风压并进行积分的方法研究高层建筑的动态风干扰。模型表面的瞬态风压利用多通道同步压力测量而得到。为提高数值积分精度,测压孔位置按高斯求积节点布置。设计了表面布置有测压孔的受扰高层建筑刚性模型和三种不同高度的干扰建筑模型,研究了相同高度以及不同高度的两个高层建筑之间的顺风向和横风向动态风干扰。借助干扰因子讨论了近邻建筑的位置、距离以及楼高对受扰建筑基础动态倾覆力矩的影响规律,并与传统方法所得结果作了比较。     

高层与超高层框架——芯筒结构中刚性加强层的布置对侧移控制作用的研究

采用文献［１］构造的有旋转自由度的平台单元，建立起有刚性加强层的框架—芯筒结构计算模型，对刚性加强层在高层建筑结构控制侧移方面的作用进行较精确的数值分析，计算结果可供高层建筑结构设计工作者参考     

Precision measurements of kaonic atoms at DA ΦNE and future perspectives

The DAΦNE electron-positron collider at the Frascati National Laboratories has made available a unique “beam" of negative kaons providing unprecedented conditions for the study of the low-energy kaon-nucleon interaction, a field still largely unexplored. The DEAR (DAΦNE Exotic Atom Research) experiment at DAΦNE and its successor SIDDHARTA (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) aim at a precision measurement of the strong-interaction shift and width of the fundamental 1s level, via the measurement of the X-ray transitions to this level, for kaonic hydrogen and kaonic deuterium. The aim is to extract the isospin-dependent antikaon-nucleon scattering lengths and to contribute to the understanding of aspects of chiral symmetry breaking in the strangeness sector.     

乌鲁木齐市既有居住建筑采暖现状和改造形式浅析

建筑物使用过程中,能源消耗以采暖和空调所占的比例最大约为65％．采暖能耗是建筑能耗的最主要部分．也是浪费最为严重和节能潜力最大的部分．为贯彻落实国家提出的建设资源节约型和环境友好型社会的要求,有效降低建筑采暖能耗,既有建筑的节能改造成为开展节能工作的重点．本文就乌鲁木齐市既有居住建筑供热现状和建筑采暖方式进行了基础调查分析,并对采暖系统节能改造和新建居住建筑采暖系统形式进行了分析,以朗为乌鲁木齐市既有居住建筑采暖系统改造提供参考．     

低层四坡屋面房屋风载体型系数的分析与实用计算

利用数值模拟和风洞模型试验,获得了低层四坡屋面房屋在不同风向角下的屋面风载体型系数的实用计算公式。首先对缩尺比为1∶20的四坡屋面房屋模型(足尺为平面7.5 m×15 m,檐口高度9.6 m,挑檐长度1.5m)进行了风洞试验,再通过改变体型参数对5种屋面坡角、5种房屋高宽比和长宽比情况的屋面风压进行了数值模拟。通过对数值模拟和试验结果的分析发现,屋面坡角及房屋高宽比是影响屋面风荷载的主要因素。据此提出了屋面各分区风载体型系数的实用计算公式,并给出了计算实例,将计算结果与试验结果作了比较。结果表明,该实用公式简便准确,可直接供四坡屋面房屋抗风设计参考和应用。     

Zero finite-temperature charge stiffness within the half-filled 1D Hubbard model

Even though the one-dimensional (1D) Hubbard model is solvable by the Bethe ansatz, at half-filling its finite-temperature T>0$T>0$ transport properties remain poorly understood. In this paper we combine that solution with symmetry to show that within that prominent T=0$T=0$ 1D insulator the charge stiffness D(T)$D\left(T\right)$ vanishes for T>0$T>0$ and finite values of the on-site repulsion U$U$ in the thermodynamic limit. This result is exact and clarifies a long-standing open problem. It rules out that at half-filling the model is an ideal conductor in the thermodynamic limit. Whether at finite T$T$ and U>0$U>0$ it is an ideal insulator or a normal resistor remains an open question. That at half-filling the charge stiffness is finite at U=0$U=0$ and vanishes for U>0$U>0$ is found to result from a general transition from a conductor to an insulator or resistor occurring at U=U_c=0$U=U_c=0$ for all finite temperatures T>0$T>0$. (At T=0$T=0$ such a transition is the quantum metal to Mott-Hubbard-insulator transition.) The interplay of the η$\eta$-spin SU(2)$SU\left(2\right)$ symmetry with the hidden U(1)$U\left(1\right)$ symmetry beyond SO(4)$SO\left(4\right)$ is found to play a central role in the unusual finite-temperature charge transport properties of the 1D half-filled Hubbard model.     

Numerical study of the thermal behavior of bi-zone buildings

This work aims at studying the thermal behavior of bi-zone buildings by the nodal method (using the FORTRAN simulation: DIGITAL Visual FORTRAN 95) based on an electrical analogy. The building temperature is assumed to be variable with time or imposed at a setpoint temperature. The results show the influence of various parameters (weather temperature, setpoint temperature of the indoor air in each zone) and the effect of common wall, which is composed by the alveolar structure in two different senses (insulating and conducting ones), on the thermal behavior of a building.     

Modeling vortex-shedding effects for the stochastic response of tall buildings in non-synoptic winds

This study derives a model for the vortex-induced vibration and the stochastic response of a tall building in strong non-synoptic wind regimes. The vortex-induced stochastic dynamics is obtained by combining turbulent-induced buffeting force, aeroelastic force and vortex-induced force. The governing equations of motion in non-synoptic winds account for the coupled motion with nonlinear aerodynamic damping and non-stationary wind loading. An engineering model, replicating the features of thunderstorm downbursts, is employed to simulate strong non-synoptic winds and non-stationary wind loading. This study also aims to examine the effectiveness of the wavelet-Galerkin (WG) approximation method to numerically solve the vortex-induced stochastic dynamics of a tall building with complex wind loading and coupled equations of motions. In the WG approximation method, the compactly supported Daubechies wavelets are used as orthonormal basis functions for the Galerkin projection, which transforms the time-dependent coupled, nonlinear, non-stationary stochastic dynamic equations into random algebraic equations in the wavelet space. An equivalent single-degree-of-freedom building model and a multi-degree-of-freedom model of the benchmark Commonwealth Advisory Aeronautical Research Council (CAARC) tall building are employed for the formulation and numerical analyses. Preliminary parametric investigations on the vortex-shedding effects and the stochastic dynamics of the two building models in non-synoptic downburst winds are discussed. The proposed WG approximation method proves to be very powerful and promising to approximately solve various cases of stochastic dynamics and the associated equations of motion accounting for vortex shedding effects, complex wind loads, coupling, nonlinearity and non-stationarity.