The experimental results of micro-structure in grid-produced turbulence

The variation of main turbulent quantities in an isotropic turbulent flow, such as the decay of turbulent energy and the variation of Taylor microscale of turbulence with time are obtained, by employing a hot-wire anemometer and a nearly isotropic turbulent flow which is produced by a gridscreen located at the entrance of the test section in a low-level turbulence and low-speed wind tunnel in Peking University. The experimental results of the decay of turbulent energy and the variation of Taylor microscale of turbulence with time at the whole period from initial to final stage, normalized in an non-dimensional form, are consistent quite well with the computational results by the theory of the statistical vorticity structure^[1]. The experimental results presented in this paper also agree with Townsend's results obtained in earlier years^[2] as well as with Bennett's in the seventy's^[3].     

响应面重构的若干方法研究及其在可靠度分析中的应用

在地下隧洞稳定的可靠性分析中，得到极限状态方程的解析表达式往往是非常困难的。因而本文基于数值模拟研究了响应面重构的若干方法，以模拟实际工程中常见的功能函数不能明确的可靠度计算问题。重点探讨了有理多项式技术和人工神经网络方法在响应面重构中的应用，并与目前常用的两种响应面方法进行了比较分析。最后,通过程序编制和算例分析对响应面重构的若干方法研究进行了验证。     

高超声速钝锥流场红外辐射实验研究

报道了在JF-10氢氧爆轰驱动高焓激波风洞中开展的再入流场红外辐射实验研究. 风洞的试 验状态为：驻室总压19.6MPa, 总焓15.5MJ/kg, 自由流速度约5 km/s. 实验以锑化铟多元红外成像系统为测量手段，以球头钝锥体为试验模型，测量激波层与近尾流中红外辐射功率 的横向分布剖面. 试验数据呈现明显的规律性. 试验结果表明，激波层内壁面附近的红外辐 射功率较小，中间有一区域辐射较大且相对均匀，激波层外缘辐射单调减小；尾流中红外辐 射功率在轴线附近的核心区最大，随着离轴线距离的增大而单调减小.     

铁路深埋隧道区岩溶发育特征研究

对圆梁山隧道毛坝向斜段揭露溶洞进行分析的基础上 ,结合向斜区岩溶分布的勘察 ,对毛坝段深层岩溶发育特征及影响因素进行了研究。认为岩溶水在水力坡度或压力水头 ,尤其是水重力的作用下有不断向深层运移的趋势 ,所以在水具有侵蚀性的前提下 ,岩溶也具有向深层发育的趋势 ,并在厚层隔水底板及排泄基准面附近形成岩溶较发育带。而岩溶分布的层位及构造部位 ,在同一地质单元中的浅层和深层区具有类似性     

沉管隧道地震响应分析中的三维接触模型与算法研究

针对土体与埋置在土体中的管段以及沉管隧道各个柔性接头处不同构件之间的动力相互作用,采用基于超级计算机的三维接触模型对上海某沉管隧道进行了地震响应分析,并进行了三维接触算法的研究。整个模型单元数超过了120万,节点数超过了100万。研究证明,应用文中提出的接触模型和算法可将接触处理的CPU时间大大缩短。地震波载荷选用调幅后的唐山地震波,应用通用非线性动力分析有限元程序LS-DYNA进行求解,计算结果可为隧道的抗震设计提供有力依据。     

公路隧道防排水技术进展

综述了公路隧道近几十年防排水技术的进展。其内容包括 :公路隧道防排水技术标准 ,复合式衬砌防排水技术 ,断层、破碎带地层中的防排水技术 ,隧道导排水结构。并结合某些工程问题进行了讨论。     

地铁隧道工程的应力监测

本文利用应变电测法，对天津地铁隧道工程进行现场应力监测。为保证施工安全和优化工程设计，提供了可靠测试数据。     

RESPONSE CHARACTERISTICS OF WIND EXCITED CABLES WITH ARTIFICIAL RIVULET

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｒｅｈａｖｅｂｅｅｎｍａｎｙｒｅｐｏｒｔｓｉｎｔｈｅｐａｓｔｔｅｎｙｅａｒｓｏｎｅｘｃｅｓｓｉｖｅａｎｄｕｎａｎｔｉｃｉｐａｔｅｄｖｉｂｒａｔｉｏｎｏｆｃａｂｌｅｓｉｎｃａｂｌｅｓｕｐｐｏｒｔｅｄｂｒｉｄｇｅｓｕｎｄｅｒｔｈｅｓｉｍｕｌｔａｎｅｏｕｓｏｃｃｕｒｒｅｎｃｅｏｆｗｉｎｄａｎｄｒａｉｎ[1-5] .Ｔｈｅａｕｔｈｏｒｓａｌｓｏｏｂｓｅｒｖｅｄｗｉｎｄ＿ｒａｉｎｉｎｄｕｃｅｄｃａｂｌｅｖｉｂｒａｔｉｏｎｆｒｏｍａｃａｂｌｅ＿ｓｔａｙｅｄｂｒｉｄｇｅｒｅｃｅｎｔｌｙ…     

回转筒体轴向窜动的力学性能分析及控制

基于长期生产实践，针对回转窑筒体在运转时发生持续下滑，引起系统频发故障，造成停机的问题，应用弹性滑动理论和摩擦传动理论分析论证了窑体下滑的原因；给出了窑体轴向滑动速度的计算方法；介绍了控制窑体轴向窜动的方法。     

Mass spectrometric measurements of the freestream composition in the T4 free-piston shock-tunnel

The freestream composition is an important parameter in ground-based aerodynamic testing, and direct measurement of it is very important. This paper reports extensive composition measurements in the freestream of the T4 free-piston shock-tunnel, employing a recently improved time-of-flight mass spectrometer. A wide range of nozzle reservoir conditions were used. The results show good agreement between measured and theoretical values for nitric oxide over the entire enthalpy range reported (2.5–13 MJ/kg). This provides confidence that the chemistry model is correctly predicting sudden freezing of NO in the nozzle expansion. On the other hand, no monatomic species have been measured other than those produced by dissociative ionisation within the mass spectrometer, even at flow conditions where significant freestream dissociation is expected. Furthermore, excess diatomic oxygen is detected at high enthalpies. These observations are consistent with the possibility that oxygen recombination is not correctly predicted in the nozzle expansion, with sudden freezing occurring significantly later than predicted. However, the observations are also consistent with possible catalytic recombination in the skimmer system. The possibility for producing an empirical correlation between the freestream composition and the reservoir entropy has also been observed. PACS 07.75.th; 47.40.-x