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《矿业科学技术学报(英文版)》2016,26(6):1117-1123
In order to study the influence of depth-thickness ratio on bedding slope stability, whose sliding surface is flexural concave in shape under mining conditions, this paper aims to study the characteristics of deformation and damage of bedding sliding with depth-thickness ratios of 200:1, 150:1, 120:1, 100:1 and 50:1by adopting numerical simulation analysis software combined with laboratory-made ‘‘under the influence of mining variable sliding surface slope similar simulation test bed", and to propose identification methods for slope stability under the influence of mining. The results show that mining activities under the slope reduce slope stability. With a decrease in the mining depth ratio, the influence of mining on the slope increases gradually, and the damage to the slope gradually expands, the stability of the slope gradually reduces, fracture occurs on the slope toe and the central fissure gradually develops to the surface,and reaches slide threshold when the depth-thickness ratio is 50:1. 相似文献
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以声波法为基础的无损检测技术已经逐渐取代传统的拉拔实验成为锚杆锚固质量检测的主要手段。随着锚杆锚固技术在各类土木工程中的应用日益增加,锚杆锚固质量无损检测数据处理方法的研究工作也越来越受到重视。本文在分析锚杆锚固质量无损检测原理的基础上提出了以Hilbert变换为基础的数据处理方法,并将该方法应用于实际工程中,验证了其可行性。 相似文献
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The design of critical aerospace alloys is primarily built on optimizing strength and ductility, both of which can be enhanced by controlling the alloying element additions as well as heat treatment conditions. The 7075 alloy is one such aerospace alloy. The main objective of this study was to optimize the 7075 strength. Several experimental alloys were prepared and tensile test bars were cast using an ASTM B-108 type permanent metallic mold. The as-cast samples were then solution heat-treated at 470 °C for times up to 48 h. The solution heat-treated bars were also aged in order to improve the alloy strength through precipitation hardening. Line scans for Mg, Cu and Zn were obtained from the various heat-treated alloy samples using an electron probe microanalyzer equipped with Energy Dispersive X-ray (EDX) and Wavelength Dispersive Spectroscopic (WDS) facilities. Peaks corresponding to the Mg, Cu and Zn concentrations in the as-cast samples disappeared after solution treatment, reflecting optimized homogeneity structures. The newly developed versions of the 7075 alloy displayed an ultimate tensile strength (UTS) of ∼1 GPa. 相似文献
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By using the π-conjugated phthalocyanine macrocycle as the versatile building block, a series of five sandwich-type ethylthio substituted phthalocyaninato europium complexes, namely double-decker Eu[Pc(SC2H5)8]2 (Pc-1), triple-decker Eu2[Pc(SC2H5)8]3 (Pc-2), and their corresponding dimers, [Pc(SC2H5)8]2Eu2[BiPc(SC2H5)12] (Pc-1@Pc-1), [Pc(SC2H5)8]3Eu3[BiPc(SC2H5)12] (Pc-1@Pc-2) and [Pc(SC2H5)8]4Eu4[BiPc(SC2H5)12] (Pc-2@Pc-2), are synthesized and prepared into the solution-processed films by a simple quasi-Langmuir-Shäfer (QLS) method. Combination between the extending π-conjugated system in the longitudinal and transverse directions of Pc macrocycles and/or radical nature of Pc-1 unit among different semiconducting molecules result in unusually small energy gaps (0.345–0.91 eV). Consequently, all of the semiconductors exhibit excellent conductivities. Among these materials, the conductivity for the radical species Pc-1@Pc-1, Pc-1@Pc-2 and Pc-1 is about 3–4 times larger than that for the non-radical compounds Pc-2@Pc-2 and Pc-2. Moreover, the QLS films of five semiconductors take excellent linear responses for both oxidizing NO2 (100–300 ppb) and reducing NH3 (4–8.6 ppm). Respectively, the sensitivity (in % ppm−1) gets increased in the order of Pc-1 < Pc-2 < Pc-1@Pc-1 < Pc-1@Pc-2 < Pc-2@Pc-2 for NO2, and Pc-1@Pc-2 < Pc-1 < Pc-1@Pc-1 < Pc-2@Pc-2 < Pc-2 for NH3. Depending on the highly extended π-conjugated systems, Pc-2@Pc-2 and Pc-2 films achieve the highest sensitivity of 208.2% ppm−1 and 0.97% ppm−1 to NO2 and NH3, respectively. In addition, with a less than 2 min response time within a limit of detection at 10 ppb for NO2 and 0.48 ppm for NH3, good reproducibility and selectivity have been revealed for the Pc-2@Pc-2 and Pc-2 films among the best gas sensors obtained so far for all the solution-processed films based on organic semiconductors in dry air at room temperature. More importantly, it is firstly demonstrated that the high NO2 sensing is resulted from low Oxd1, and high NH3 sensing is resulted from high Red1 among the sandwich Pc-based semiconductors. 相似文献
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《矿业科学技术学报(英文版)》2016,26(6):959-966
Classification systems such as Slope Mass Rating(SMR) are currently being used to undertake slope stability analysis. In SMR classification system, data is allocated to certain classes based on linguistic and experience-based criteria. In order to eliminate linguistic criteria resulted from experience-based judgments and account for uncertainties in determining class boundaries developed by SMR system,the system classification results were corrected using two clustering algorithms, namely K-means and fuzzy c-means(FCM), for the ratings obtained via continuous and discrete functions. By applying clustering algorithms in SMR classification system, no in-advance experience-based judgment was made on the number of extracted classes in this system, and it was only after all steps of the clustering algorithms were accomplished that new classification scheme was proposed for SMR system under different failure modes based on the ratings obtained via continuous and discrete functions. The results of this study showed that, engineers can achieve more reliable and objective evaluations over slope stability by using SMR system based on the ratings calculated via continuous and discrete functions. 相似文献
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主要介绍平面转弯带式输送机技术方案的设计计算及实现平面转弯的技术要点,保证托辊具有一定的安装支撑角,构成内曲线抬高角,增大成槽角,对线路进行合理设计,使普通带式输送机实现了平面转弯运行,并确定转弯半径和驱动功率,又用类比法对驱动装置进行了选型。具有良好的推广应用前景。 相似文献
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《Measurement》2016
The fiber Bragg grating geophone sensor with higher sensitivity and wider frequency range was reported. The methods to increase the sensitivity of the FBG cantilever sensor were presented. The acceleration sensitivity of the optimized FBG geophone is 220 pm/g, and the resonant frequency can reach to 295 Hz. The experiments show that the FBG geophone system has the minimum detectable acceleration of 1 mm/s2. Some factual application examples of using this fiber Bragg grating geophone monitoring system for micro seismic monitoring in coal mine were presented. 相似文献