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41.
Influence analysis of bracket set on seismic performance of steel eave columns in Chinese traditional style buildings 下载免费PDF全文
Jianyang Xue Linlin Ma Zhanjing Wu Weixin Gao 《The Structural Design of Tall and Special Buildings》2018,27(8)
This paper presents influence analysis of bracket set on seismic performance of steel eave columns in Chinese traditional style buildings. Eight 1/1.5‐scale steel eave columns were constructed and tested under low cyclic reversed loading, including 4 specimens with bracket set and 4 specimens without bracket set. Based on the analysis of the strain of the specimens, the failure modes of the specimens were obtained. In addition, the hysteresis loops, skeleton curves, degradations of stiffness and strength, ductility, and dissipation capacities of the specimens were analyzed. Bracket set changed the force transfer mechanisms and failure modes of the specimens and had a significant influence on the seismic performance of the specimens. Compared with the specimens without bracket set, the yielded and ultimate bearing capacities of the specimens with bracket set improved by 30.7% and 24.0%, respectively. And also, the stiffness of the specimens with bracket set at the yielded and ultimate points increased by 52.8% and 135.6%. The dissipation capacities of the specimens with bracket set were 2.12 times those of the specimens without bracket set at yielded load. However, the ductility of the specimens with bracket set slightly decreased by 8.5%. It was shown that the seismic performance of the specimens with bracket set was better than that of the specimens without bracket set. The work in this paper provides a basis for further theoretical study on the seismic performance of steel eave columns in Chinese traditional style buildings. 相似文献
42.
以三塘湖盆地中、低煤阶煤层含气量和主要气体成分为基础,结合盆地构造、沉积及水文地质特征,对汉水泉凹陷和条湖凹陷煤层甲烷风化带进行了划分,并对库木苏凹陷、马朗凹陷、淖毛湖凹陷和苏鲁克凹陷煤层甲烷风化带进行了预测。结果表明,三塘湖盆地甲烷风化带深度为400~1000 m.由于受东北冲断隆起带的影响,三塘湖盆地北部甲烷风化带浅于南部。沉积方面,盆地东部淖毛湖凹陷、马朗凹陷和条湖凹陷深湖—半深湖和辫状河三角洲成煤环境优于盆地西部汉水泉凹陷和库木苏凹陷扇三角洲成煤环境,盆地东部甲烷风化带普遍浅于西部;水文地质方面,条湖凹陷和马朗凹陷中开启性局部滞留水文地质单元形成的甲烷风化带浅于其他凹陷封闭性弱径流水文地质单元的甲烷风化带。初步预测马朗凹陷北部为下一步煤层气勘探开发的优势区块,条湖凹陷北部为下一步煤系气勘探开发的优势区块。 相似文献
43.
研究以"翠香"猕猴桃为试材,比较两种温度(0±0.5℃和2±0.5℃)下,贮藏果实的冷害发生情况及品质差异,同时关注果实贮藏期间果实苦味的产生,以期找出果实苦味产生的原因。结果表明,0±0.5℃贮藏时,果实硬度保持较好,果实呼吸强度下降,有冷害和褐变发生,并伴有果实发苦现象;而2±0.5℃贮藏的果实未见冷害和褐变发生,色度得以保持,多酚氧化酶(PPO)和过氧化物酶(POD)活性下降,极显著延缓了细胞膜透性的升高,此外,果实可溶性固形物和维生素C的含量也显著提高,果实没有出现苦味。试验中发现"翠香"猕猴桃苦味现象和冷害伴随产生,并随着冷害发展加重,推测"翠香"果实的苦味可能是由冷害造成的。 相似文献
44.
在对沁水盆地赵庄矿煤层气开发地质、煤层气生产井资料深入研究的基础上,分析、总结了区内煤层气直井低产原因,并据此提出了区内地面抽采后续开发方向。研究认为:3号煤层气含量偏低、含气饱和度低、临储比低,致使排采阶段气含量可降幅度低,是其低产的宏观表征;3号煤储层不匹配孔级,较差连通性,即微、小孔为主,中孔次之,大孔不发育,微裂隙连通性差,致使扩散缓慢、影响储层改造和抽采效果,是其低产的微观表征;3号煤层远高于顶底板塑性及相近的水平应力,进一步造成改造缝长受限,泄流面积不足。因此,建议区内后续地面抽采方式应以增大泄流面积开发方式为主。 相似文献
45.
Yu Liu Xing Zou Xiaowei Niu Zhengquan Hu 《International Journal of Circuit Theory and Applications》2020,48(12):2056-2064
According to the characteristics of the chaotic oscillator in detecting weak signals, an algorithm based on Duffing chaotic oscillator array was proposed for acquisition of weak GLONASS signals. By means of GLONASS intermediate frequency and Duffing chaotic oscillator models, Lyapunov exponent is adopted to judge the critical condition of phase track and decide whether GLONASS signals exist or not by the change of the critical condition, and numeric iteration procedure is used to calculate the exponent. Finally, the performance of algorithm is simulated using GLONASS intermediate frequency data. The results indicate that acquisition algorithm can satisfy the need of object positioning in low signal-to-noise ratio environment. 相似文献
46.
Daylon Black Ryan Harper Patrick Ward Jacob Davlin Omar Bentancourt Donald Plumlee Jim Browning 《International Journal of Applied Ceramic Technology》2020,17(5):2393-2406
A low temperature co-fired ceramic (LTCC) material system has been used to develop a protype field emission cathode structure for use in an experimental magnetron oscillator. The structure is designed for used with 30 gated field emission array (GFEA) die electrically connected through silver metal traces and electrical vias. To approximate a cylinder, the cathode structure (48 mm long and 13.7 mm in diameter) is comprised of 10 faceted plates which cover the GFEA dies. Slits in the facet plates allow electron injection. The GFEA die (3 mm × 8 mm) are placed in axial columns of 3 and spaced azimuthally around a cylindrical support structure in a staggered configuration resulting in 10 azimuthal locations. LTCC manufacturing techniques were developed in order to fabricate the newly designed cathode with seven layers wrapped to form the cylinder with electrical traces and vias. Two different cathode wrapping techniques and two different via filling techniques were studied and compared. Two different facet plate manufacturing techniques were studied. Finally, four different support stand configurations for firing the cylindrical structure were also compared with a square post stand having the best circularity and linearity measurements of the fired structure. 相似文献
47.
Bilal Shahid Dangqiang Zhu Qian Wang Xiyue Yuan Irfan Ismail Yao Wu Zurong Du Renqiang Yang 《Polymer International》2020,69(6):564-570
To optimize the energy levels of the structural framework of isoindigo polymers, a series of asymmetric isoindigo based low bandgap polymers with chlorine, fluorine and thiazole substituents was constructed and their optical, electrochemical and photovoltaic properties were comparatively evaluated for the impact of different substitutions. In comparison with the polymer based on 2,2'‐bithiophene and isoindigo unit (PTi) with non‐substituted bithiophene as the donor moiety, the highest occupied molecular orbital energy level for the newly synthesized polymers is significantly decreased, and in turn an improvement of the open‐circuit voltage (VOC) is noted in the corresponding photovoltaic devices. More importantly, combined with a low bandgap of 1.32 eV, the energy losses (Eloss) could be reduced to 0.61 eV for polymer based on chlorinated 2,2'‐bithiophene and isoindigo unit (PCl). In addition, the halogen moieties are observed to be superior in device fabrication and give better values than the thiazole substituent. Both fluorinated and chlorinated polymer donors exhibited improved performance compared with the original polymer PTi. Consequently, this work not only presents the influence of different electron withdrawing substituents on the physicochemical and photovoltaic performance, but also backs the concept of how to reduce the energy loss via the heteroatom effect. © 2020 Society of Chemical Industry 相似文献
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《Journal of the European Ceramic Society》2020,40(4):1186-1190
Two melilite ceramics Sr2AGe2O7 (A = Mg, Zn) with low permittivity were prepared by a solid-state reaction method. The crystal structure and microstructure of the ceramics were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and scanning electron microscopy. Both ceramics crystallized in a single melilite structure with a tetragonal space group P-42m (113) and exhibited homogeneous microstructures. Optimum microwave dielectric properties with relative permittivity (εr) of 8.56, quality factor (Q × f) of 28,800 GHz, and temperature coefficient of resonance frequency (τf) of −70.5 ppm/°C were obtained in Sr2MgGe2O7 sintered at 1330 °C. Sr2ZnGe2O7 possessed εr of 8.81, Q × f of 35,700 GHz, and τf of −84.4 ppm/°C when sintered at 1290 °C. Thermal stability of resonance frequency was accessible when the negative τf values of Sr2AGe2O7 were adjusted after the formation of composite ceramics with CaTiO3. 相似文献