基于特征建模的TDD系统大气波导干扰控制体系研究

大气波导干扰是特定气象条件下发生的时分双工（time-division duplex，TDD）系统内干扰，是TDD移动通信系统大规模组网面临的顽疾。在总结分析大气波导干扰成因和分类等的基础上，对大气波导干扰进行建模和表征，验证了海量干扰源在时域和频域的功率集总特征，并结合大量4G/5G现网实测数据给出了典型条件下内陆波导和海面波导的量化干扰信号传播模型，对于干扰的预测和预防具有重要意义。基于干扰特征，给出了TDD系统预防大气波导干扰的帧结构与组网的4项设计原则，5G现网数据表明干扰控制方案有效，上行干扰下降10 dB以上，相关原则对于6G系统的设计也具有指导意义。     

Flame characteristics of premixed H2-air mixtures explosion venting in a spherical container through a duct

The explosion venting duct can effectively reduce the hazard degree of a gas explosion and conduct the venting energy to the safe area. To investigate the flame quantitative propagation law of explosion venting with a duct, the effects of hydrogen fraction and explosion venting duct length on jet flame propagation characteristics of premixed H₂-air mixtures were analyzed through experiment and simulation. The experiment results under initial conditions of room temperature and 1 atm show that when hydrogen fraction was high enough, part of the unburned hydrogen was mixed with air again to reach an ignitable concentration, resulting in the secondary combustion was easier produced and the duration of the secondary flame increased. With the increase of venting duct length, the flame front distance and propagation velocity increased. Meanwhile, the spatial distribution of pressure field and temperature field, and the propagation process and mechanism of the flame venting with a duct were analyzed using FLUENT software. The variation of the pressure wave and the pressure reflection oscillation law in the explosion venting duct was captured. Therefore, in the industrial explosion venting design with a duct, the hazard caused by the coupling of venting pressure and venting flame under different fractions should be considered comprehensively.     

风管摩擦阻力的直接计算方法

提出用高精度的反映密度、黏度和温度关系的经验公式和Colebrook公式计算风管摩擦阻力系数的方法。分析和算例表明，用该方法计算，计算结果比采用常用工程设计方法更为准确，为应用计算机进行风道设计提供了直接、简便的方法。     

住宅厨房共用排烟系统性能比较

介绍了当地住宅厨房通风设计的发展简况，比较了两种房共用排烟系统的构造，尺寸，性能，造价及能耗，对厨房通风设计和施工提出了建议。     

空调系统柔性风管压力损失特性实验与分析

介绍了柔性风管压力损失的理论模型。通过实验研究了两种常用柔性风管在全伸展状态时的压力损失,得出了它们的绝对粗糙度值。给出了柔性风管完全展开时的阻力计算图,可供工程设计时使用。     

Numerical experiments of preconditioned Krylov subspace methods solving the dense non-symmetric systems arising from BEM

Discretization of boundary integral equations leads, in general, to fully populated non-symmetric linear systems of equations. An inherent drawback of boundary element method (BEM) is that, the non-symmetric dense linear systems must be solved. For large-scale problems, the direct methods require expensive computational cost and therefore the iterative methods are perhaps more preferable. This paper studies the comparative performances of preconditioned Krylov subspace solvers as bi-conjugate gradient (Bi-CG), generalized minimal residual (GMRES), conjugate gradient squared (CGS), quasi-minimal residual (QMR) and bi-conjugate gradient stabilized (Bi-CGStab) for the solution of dense non-symmetric systems. Several general preconditioners are also considered and assessed. The results of numerical experiments suggest that the preconditioned Krylov subspace methods are effective approaches solving the large-scale dense non-symmetric linear systems arising from BEM.     

云台山隧道进口黄土段施工技术

从防排水、边仰坡支护、洞口加固、洞内超前支护、钢拱架锚喷联合支护等方面详细介绍了云台山隧道进口黄土段的施工技术,总结了该隧道的施工效果,强调了黄土隧道施工中防排水超前支护预注浆、施工监控的作用,积累了隧道施工经验.     

改造加热炉系统 提高加热炉热效率

分析了重整装置加热炉热效率低的原因，介绍了提高加热炉热效率采取的几项措施。     

The result of a wall failure in-pile experiment under the EAGLE project

The WF (wall failure) test of the EAGLE program, in which 2 kg of uranium dioxide fuel-pins were melted by nuclear heating, was successfully conducted in the IGR (Impulse Graphite Reactor) of NNC/Kazakhstan. In this test, a 3 mm-thick stainless steel (SS) wall structure was placed between fuel pins and a 10 mm-thick sodium-filled channel (sodium gap). During the transient, fuel pins were heated, which led to the formation of a fuel-steel mixture pool. Under the transient nuclear heating condition, the SS wall was strongly heated by the molten pool, leading to wall failure. The time needed for fuel penetration into the sodium-filled gap was very short (less than 1 s after the pool formation). The result suggests that molten core materials formed in hypothetical LMFBR core disruptive accidents have a certain potential to destroy SS-wall boundaries early in the accident phase, thereby providing fuel escape paths from the core region. The early establishment of such fuel escape paths is regarded as a favorable characteristic in eliminating the possibility of severe re-criticality events. A preliminary interpretation on the WF test results is presented in this paper.     

中国低空大气波导出现概率和波导特征量的统计分析

本文简要说明了我们对大气波导的统计方法，并对统计结果作了讨论和分析。文中详细讨论了中国低空大气波导在不同地区的出现情况，说明了它们在各地出现概率随季节月份的变化情况及日变化情况，还说明了悬空波导和贴地波导基本分布状况；对于波导顶高、强度、厚度、高度等特征量，主要给出了它们的平均值和波导在不同数值上的分布。结果表明，我国低空大气波导出现的高概率区是南部沿海、东南沿海、东部沿海和西北地区中部；我国的四大高原、天山以北和东北平原是无波导区；我国低空大气波导的顶高一般在地面上２０００ｍ以内，强度在０～２０Ｍ单位之间，厚度一般是１００～５００ｍ，高度是西北地区绝大部分为０米，沿海地区大多数超过３００ｍ。同时文中也讨论了我国低空大气波导的分布和我国各地的具体地理位置、气候条件的相关情况。