虚拟声屏障在变压器低频降噪中的实验研究

针对开口房间内的变压器,在开口处布放若干扬声器和误差传声器构成虚拟声屏障,实验研究了虚拟声屏障对通过开口向外辐射的低频线谱噪声的控制效果。将15个次级源近似均匀分布在面积为2 m′ 2.7 m的开口面上,左右间距约58.5 cm、上下间距45-65 cm,15个误差传声器分别位于对应的次级源正前方1 m,系统采用自适应谐波降噪算法。结果表明：虚拟声屏障系统在误差点100 Hz、200 Hz和300 Hz的平均降噪量分别达到12.7 dB、19.9 dB和22.2 dB,虚拟声屏障对100 Hz、200 Hz、300 Hz线谱噪声的控制效果与单层封闭窗户相当,且内部合成参考信号,无需外接参考传声器。采用虚拟声屏障对开口房间内的变压器降噪的好处是实现室内外的自然通风,便于变压器的散热。     

基于多指标区间逼近的住宅建筑节能改造方案评价

鉴于住宅建筑节能改造的效果的总体评价的复杂性及其影响因素的不确定性,将区间数关联决策方法应用于节能改造效果的评价领域.通过引入区间数序列的范数完成多指标决策矩阵的规范化处理,建立多指标区间数整体逼近关联决策模型,完成住宅建筑节能效果评估得出最终结论.计算实例验证了该模型的有效性和实用性,较好地解决了住宅建筑节能改造效果评价的实际问题,取得较为满意的结果.     

Equivariant Novikov conjecture for groups acting on Euclidean buildings

We prove the equivariant Novikov conjecture for groups acting on Euclidean buildings by using an equivariant Hilsum-Skandalis method. We also obtain an equivariant version of the Connes-Gromov-Moscovici theorem for almost flat -algebra bundles.

     

A review on research of fire dynamics in high-rise buildings

Since serious fire occurred frequently in recent years, fire safety of high-rise building hasattracted extensive attention. A National Basic Research Program (973 program) of China has been setup by Ministry of Science and Technology (MOST) of China in 2012 to meet the research requirementsof fire safety in high-rise buildings. This paper reviews the current state of art of research onfire dynamics of high-rise buildings, including the up-to-date progress of this project. Thefollowing three subjects on fire dynamics of high-rise buildings are addressed in this review: theejected flame and fire plumebehavior over facade out ofthe compartment window, the flame spread behavior over facade thermal insulation materials, and the buoyancy-driven smoke transportationcharacteristicsalong long vertical channels in high-rise buildings. Prospective future works are discussed andsummarized.     

三维爆炸与冲击问题仿真软件研究

针对三维复杂爆炸流场的数值模拟,开发了欧拉型三维爆炸与冲击问题数值模拟软件EXPLOSION-3D,对该软件的三个组成模块即计算程序MMIC-3D、有限差分网格自动生成前处理程序MESH-3D和可视化后处理程序VISC-3D的基本理论和算法进行了讨论。以楼群中爆炸流场的三维数值模拟为例,采用该软件对大型爆炸发生后形成的爆炸场进行了数值模拟研究,得到一些有意义的数值结果,这些结果对于爆炸灾害的预防和评估具有重要的参考价值。     

高层钢-混凝土混合结构地震作用下的能量反应分析

针对目前高层建筑混合结构中常用的外钢框架-内混凝土核心筒混合结构,从地震能量输入和结构能量耗散的角度对其进行了地震作用下的能量反应分析.通过选取不同的地震动参数对混合结构的总输入能及其在滞回耗能和阻尼耗能之间的分配情况进行了研究,明确了地震动各参数的变化对混合结构能量反应的影响;通过分析不同地震波作用下混合结构的滞回耗能在外钢框架和内混凝土核心筒间的分布以及在结构层间的分部情况知,底层剪力墙是整个混合结构中滞回耗能比较集中的区域,地震破坏最为严重.通过本文研究知,地震反应的能量分析方法是一种能较好反应混合结构在地震作用下的地震反应全过程及其弹塑性性能的方法.     

Non-discrete affine buildings and convexity

Affine buildings are in a certain sense analogs of symmetric spaces. It is therefore natural to ask for analogs of results for symmetric spaces. We prove a version of Kostant?s convexity theorem for thick non-discrete affine buildings. Kostant proves that the image of a certain orbit of a point x in the symmetric space under a projection onto a maximal flat is the convex hull of the Weyl group orbit of x. We obtain the same result for a projection onto an apartment in an affine building. The methods are mostly borrowed from metric geometry. Our proof makes no appeal to the automorphism group of the building. However the final result has an interesting application for groups acting nicely on non-discrete buildings, such as groups admitting a root datum with non-discrete valuation. Along the proofs we obtain that segments are contained in apartments and that certain retractions are distance diminishing.     

历史文化建筑保护和力学

讨论了历史文化建筑维修、保护和力学的关系,综述了中国历史文化建筑保护中的力学问题,讨论了木质历史文化建筑结构的建模问题．介绍了世界各国和中国对文化遗产保护的发展史,及中国历史文化建筑保护现状与任务;重点介绍了力学在历史文化建筑保护领域所作的贡献和面临的机遇与挑战．并对历史文化建筑保护措施和研究方向提出建议．     

Spherical harmonic analysis on affine buildings

Let be a locally finite regular affine building with root system R. There is a commutative algebra spanned by averaging operators A _λ , λ ∈ P ⁺, acting on the space of all functions f:V _P → , where V _P is in most cases the set of all special vertices of , and P ⁺ is a set of dominant coweights of R. This algebra is studied in [6] and [7] for à _n buildings, and the general case is treated in [15]. In this paper we show that all algebra homomorphisms h: may be expressed in terms of the Macdonald spherical functions. We also provide a second formula for these homomorphisms in terms of an integral over the boundary of . We may regard as a subalgebra of the C ^*-algebra of bounded linear operators on ?²(V _P ), and we write for the closure of in this algebra. We study the Gelfand map , where M ₂= , and we compute M ₂ and the Plancherel measure of . We also compute the ?²-operator norms of the operators A _λ , λ ∈ P ⁺, in terms of the Macdonald spherical functions.     

Active vibration control of nonlinear benchmark buildings

The present nonlinear model reduction methods unfit the nonlinear benchmark buildings as their vibration equations belong to a non-affine system. Meanwhile, the controllers designed directly by the nonlinear control strategy have a high order, and they are difficult to be applied actually. Therefore, a new active vibration control way which fits the nonlinear buildings is proposed. The idea of the proposed way is based on the model identification and structural model linearization, and exerting the control force to the built model according to the force action principle. This proposed way has a better practicability as the built model can be reduced by the balance reduction method based on the empirical Grammian matrix. A three-story benchmark structure is presented and the simulation results illustrate that the proposed method is viable for the civil engineering structures.