Property A and affine buildings

Yu's Property A is a non-equivariant generalisation of amenability introduced in his study of the coarse Baum Connes conjecture. In this paper we show that all affine buildings of type , and have Property A. Together with results of Guentner, Higson and Weinberger, this completes a programme to show that all affine building have Property A. In passing we use our technique to obtain a new proof for groups acting on buildings.     

Production of slow protonium in vacuum

We descrbe how protonium, the quasi-stable antiproton-proton bound system, has been synthesized following the interaction of antiprotons with the molecular ion in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events in the ATHENA experiment, evidence is presented for protonium production with sub-eV kinetic energies in states around n = 70, with low angular momenta. This work provides a new two-body system for studies using laser spectroscopic techniques.      

基于首次超越理论的高层隔震结构基础提离易损性分析

针对基础隔震的高层建筑,基于首次超越理论,计算了各个隔震支座在非平稳随机激励下发生基础提离破坏的易损性曲线。隔震结构采用三维有限元建模,隔震支座采用Bouc-Wen模型,经过等效线性化后,应用虚拟激励法求得结构的随机响应。讨论了隔震支座的阻尼比、屈服力以及地震动输入方向对隔震支座易损性曲线的影响。研究发现:增加隔震支座的阻尼比或是增加隔震支座的屈服力都会使得隔震支座发生基础提离的破坏概率增加,地震动的输入方向对隔震支座基础提离易损性曲线影响十分显著。     

He2 and HeH molecular ions in a strong magnetic field: The Lagrange-mesh approach

Accurate calculations for the ground state of the molecular ions He³⁺₂ and HeH²⁺ placed in a strong magnetic field B?10² a.u.$B?{10}^2\text{a.u.}$ (≈2.35×10¹¹ G$\approx 2.35\times {10}^{11}\text{G}$) using the Lagrange-mesh method are presented. The Born–Oppenheimer approximation of zero order (infinitely massive centers) and the parallel configuration (molecular axis parallel to the magnetic field) are considered. Total energies are found with 9–10 s.d. The obtained results show that the molecular ions He³⁺₂ and HeH²⁺ exist at B>100 a.u.$B>100\text{a.u.}$ and B>1000 a.u.$B>1000\text{a.u.}$, respectively, as predicted in Turbiner and López Vieyra (2007) [1] while a saddle point in the potential curve appears for the first time at B∼80 a.u.$B\sim 80\text{a.u.}$ and B∼740 a.u.$B\sim 740\text{a.u.}$, respectively.     

Silica Aerogel-Rubber Composite: A Sustainable Alternative for Buildings’ Thermal Insulation

Silica aerogel composites with recycled tire rubber have been synthesized and evaluated for their potential use for thermal protection in buildings. The present work describes for the first time the preparation of silica-based aerogel composites containing recycled rubber tires reinforced with polyvinyl butyral (PVB) by hot pressing. The developed composite was extensively characterized regarding its physical, morphological, thermal and mechanical features, and the results showed their properties were relevant, leading to composites with different properties/performances. The obtained bulk density values were satisfactory, down to 474 kg·m⁻³, and very good thermal properties were achieved, namely, thermal conductivity as low as 55 mW·m⁻¹·K⁻¹ for composites with silica aerogel, recycled tire rubber and PVB. The most promising composites were those based on low bulk density and thermal conductivity values, and they were thermally stable, indicating their suitability for thermal insulation applications.     

基于物理光学法的建筑物内高功率微波耦合场分布计算

利用物理光学法计算了高功率微波在建筑物内的耦合场分布。根据建筑物墙壁和窗户的透射率可以得到墙壁内侧的透射场,将它代入到矢量衍射公式中直接计算出在整个建筑物内的透射场;根据建筑物地面的反射率得到地板表面的反射场,将它代入到矢量衍射公式中可计算出整个建筑物内的反射场;对透射场与反射场进行矢量相加,得到叠加场。将本文方法得到的场分布情况和时域有限差分法得到的场分布进行比较,二者结果一致。物理光学法的优点在于其物理图像清晰,计算量小,计算速度快,适合应用在大型建筑物内部耦合场分布计算上。     

地方建筑的保护与开发

地方建筑作为一种文化遗产,具有较高的精神和经济价值以及深远的历史意义.当前,由于人们忽视地方建筑的价值,造成地方建筑资源的衰败.对如何正确保护地方建筑这一个重要课题进行了系统的总结和论述.     

Strengthening buildings of stone masonry to resist earthquakes

Stone masonry buildings are common in many areas in the Alpine-Himalayan earthquake zone, and their failure in recent earthquakes has been the cause of many deaths. Poverty and lack of alternatives prevent the replacement of stone masonry with more ductile materials, but the brittleness of unreinforced stone masonry can be considerably reduced by the incorporation of horizontal lacings of timber or reinforced mortar.As part of a joint research project with the Turkish Earthquake Research Institute in Ankara to study low-cost upgrading strategies for rural earthquake protection, full-scale wall elements were subjected to static lateral loading test and dynamic tests on an impulse table. A simple yield-line analysis based on wall overturning was shown to be able to give a useful prediction of the mode of failure and failure load in the static test, and give guidance on the relative performance of unreinforced and reinforced walls in the dynamic test. The results of these tests were used to assess the cost-effectiveness of a large-scale programme of upgrading rural buildings in eastern Turkey.

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Sommario Gli edifici in muratura di pietra sono molto diffusi in ampie zone della regione sismica alpino-himalayana ed il loro crollo ha provocato la perdita di numerose vite umane durante gli ultimi eventi sismici. Spessola poverta' e la mancanza di alternative impediscono la sostituzione della muratura di pietra con materiali piu' duttili: ciononostante il comportamento di tale materiale puo' essere sostanzialmente migliorato incorporando cuciture orizzontali di legno od introducendo elementi metallici nei ricorsi di malta. II progetto di ricerca che si va sviluppando congiuntamente con l'Istituto Turco di Ricerca sui Terremoti di Ankara si propone di individuare una serie di provvedimenti di basso costo per migliorare la qualita' antisimica dell' edilizia rurale. In tale schema sono stati condotti una serie di esperimenti su pannelli murari in scala reale soggetti a carichi statici laterali ed a prove dinamiche su tavola vibrante. Una semplice analisi a rottura basata sul ribaltamento dell'elemento murario si e'dimostrata in grado di fornire accurate previsioni sui meccanismi e sui carichi di rottura nelle prove statiche, e dare utili indicazioni sul comportamento di pannelli semplici e rinforzati sottoposti a prove dinamiche.I risultati di tali prove sono stati utilizzati per una analisi cost-benefici per la definizone di un programma su larga scalla del miglioramento del comportamento sismico di edifici rurali nella Turchia Orientale.

     

Detecting bubbles in exotic nuclei

The occurrence of a bubble, due to an inversion of s_1/2 state with the state usually located above, is investigated. Proton bubbles in neutron-rich argon isotopes are optimal candidates. Pairing effects which can play against the bubble formation are evaluated. They cannot prevent bubble formation in very neutron-rich argon isotopes such as ⁶⁸Ar. This pleads for a measurement of the charge density of neutron-rich argon isotopes in the forthcoming years, with the advent of electron scattering experiments in next generation exotic beam facilities such as FAIR or RIBF.