龙滩水电站地下厂房开挖爆破震动衰减规律研究

在地下厂房开挖支护过程中,爆破震动控制直接影响到高边墙的稳定及岩锚梁结构安全。本文根据龙滩水电站地下厂房Ⅲ~Ⅶ层开挖爆破震动监测数据,采用统计分析方法,经二元回归计算得到主厂房岩石高边墙、岩锚吊车梁以及已喷护岩石边墙、锚索(杆)墩(头)等防护目标的爆破振速衰减规律经验公式。结果表明,地下厂房开挖过程诱发的爆破震动沿高程H方向总体没有放大现象,但衰减较为缓慢或很缓慢,这为地下厂房工程开挖爆破施工提供了理论依据。     

采用保角变换求解一类TEM模传输线的衰减常数

本文提出采用保角变换法求解一类TEM模传输线的衰减常数。通过适当的保角变换能够映射成(包括数值保角变换)正规圆同轴线或平板电容的情况均可采用这种方法。文中给出了解析结果和数值实例。     

A comprehensive study on the effect of TeO2 on the radiation shielding properties of TeO2–B2O3–Bi2O3–LiF–SrCl2 glass system using Phy-X / PSD software

The present work deals with the detailed investigations on the radiation shielding features of TeO₂–B₂O₃–Bi₂O₃–LiF–SrCl₂ glass system. The recent software namely Phy-X/PSD has been used to report the change in the photons attenuation features of this glass system with increasing the content of TeO₂ from 25 to 85 mol% between 347 keV and 2506 keV. The results show that replacing B₂O₃ with TeO₂ causes the increase in the density of the glass from 3.66 to 5.91 g cm⁻³ which lead to increase the linear attenuation factor (μ). The μ has a direct relationship with energy and has a highly large value at 0.347 MeV (between 0.550 and 0.896 cm⁻¹). The maximum effective atomic number occurs at 0.347 MeV and equals to 17.75, 19.78, 21.94, 24.24, 26.68, 29.29 and 32.07 for the TeBBiLS1- TeBBiLS7 samples. Thereafter, Z_eff decreases quickly down to 0.826 MeV, and becomes almost constant between 1.173 and 1.333 MeV and very slightly increases at 2.506 MeV. The tenth value layer results imply that increasing the weight percentage of TeO₂ in the glasses from 25 to 85 mol% can reduce the thickness needed to attenuate or block the photons. TeBBiLS1 has the maximum half value layer (HVL) and was found to be in the range of 3.034–4.823 cm and TeBBiLS7 sample has the lowest HVL. Also, the results revealed that as the density increased, the mean free path (MFP) gradually decreased, and the attenuation ability improves.     

高分子复合材料粘弹性的超声波评价

基于复数弹性理论,分别用直接接触法和水延迟透射法阐述了EPDM5Si乙丙橡胶高分子复合材料的超声波衰减系数和相速度的求解方法,并利用衰减系数和相速度相关,求解材料的储藏弹性率和损失弹性率的比值损失正切tanδ。最后用动态力学分析(DMA)方法对求得的tanδ值进行了验证,结果非常吻合。建立了适于高分子复合材料动态粘弹性的超声无损评价系统。     

工程爆破地震安全问题

本文论及与工程爆破地震安全有关的问题，主要包括瀑破地震动衰减规律、爆破地震动与爆破减震设计、分段爆破与地震动叠加、爆破地震动持续时间等。与安全相关的爆破地震动参数主要包括地震动幅值、频谱和持续时间等。为减小爆破地震的影响，爆破减震设计常采用分没爆破和预裂爆破的方法。分段爆破会产主地震动的叠加，叠加系数直接关系到等效药量的计算。瀑破地震动持续时间与叠加系数的关系甚大，对持续时间的试验与研究对爆破减震设计和工程安全都是有价值的。     

Thermoelastic Lamb waves in a transversely isotropic plate bordered with layers of inviscid liquid

Analysis for the propagation of thermoelastic waves in a homogeneous, transversely isotropic, thermally conducting plate bordered with layers of inviscid liquid or half space of inviscid liquid on both sides, is investigated in the context of coupled theory of thermoelasticity. Secular equations for homogeneous transversely isotropic plate in closed form and isolated mathematical conditions for symmetric and anti-symmetric wave modes in completely separate terms are derived. The results for isotropic materials and uncoupled theories of thermoelasticity have been obtained as particular cases. It is shown that the purely transverse motion (SH mode), which is not affected by thermal variations, gets decoupled from rest of the motion of wave propagation and occurs along an in-plane axis of symmetry. The special cases, such as short wavelength waves and thin plate waves of the secular equations are also discussed. The secular equations for leaky Lamb waves are also obtained and deduced. The amplitudes of displacement components and temperature change have also been computed and studied. Finally, the numerical solution is carried out for transversely isotropic plate of zinc material bordered with water. The dispersion curves for symmetric and anti-symmetric wave modes, attenuation coefficient and amplitudes of displacement and temperature change in case of fundamental symmetric (S₀) and skew symmetric (A₀) modes are presented in order to illustrate and compare the theoretical results. The theory and numerical computations are found to be in close agreement.     

针刺延期火帽的设计技术

分析了针刺延期火帽延期时间的影响因素,提出改善其延期时间精度的措施.通过对产品结构、延期药进行分析,设计了衰减装置.结果证明:选用合适的延期药,设计合适的传火通道和传火面积是提高延期时间精度的技术关键,并通过方案及性能试验进行验证.     

一种微波幅度均衡器的设计与仿真

该文对同轴谐振器、同轴线进行了理论上的分析和研究，并根据具体工程的实际要求，设计了一种C波段吸收型同轴式均衡器的子结构，在该子结构中主传输线采用内圆外方同轴线来代替普通的圆同轴线，得到了较大的功率容量。利用HFSS仿真软件对其进行仿真，仿真结果表明：该子结构电路不仅能对中心频率进行调节，而且能对频率衰减幅度进行调节，达到了同轴均衡器单子结构的要求，为大功率幅度同轴均衡器的设计提供了一种新的方法。     

用超声波方法检测高水基流体介质浓度的研究

通过对高水基流体介质内部组成结构及超声波在介质中衰减的分析,提出用超声波衰减测量法检测高水基流体介质浓度的方法,设计了超声波传感器的发射和接收电路,并进行了浓度检测实验。实验结果表明：超声波在高水基流体介质中的衰减与一定范围的介质浓度存在较好的线性关系。     

充粘液管材超声导波检测模式及频厚积的选择

对超声纵向导波在充粘性液体管材中的轴向功率流分布进行了计算和分析,结合了系统中导波传播的衰减系数分布曲线,以此确定了用各模式检测管材的最佳频厚积范围以及其适合检测的缺陷位置。分析表明:频厚积在0.07 MHz·mm以下,用L(0,1)模式检测较为理想,检测管内壁缺陷时更为灵敏;在0.09～O.16 MHz·mm之间用L(0,2)模式检测及在0.18～0.28 MHz·mm之间用L(0,3)模式检测时较为理想。轴向功率流分布能有效地选择检测的最佳导波模式及频厚积。