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71.
72.
南水北调中线工程运行以来,发挥了巨大社会效益,沿途及京津冀地区对其调水需求日增,渠道停水检修将带来较大风险,因此面临输水状态下渠道衬砌板破坏抢修难题。部分挖方渠道衬砌板下有复杂的渗控措施,输水状态下采用围堰干地抢修渠底和较深部位的渠坡衬砌板时,需解决围堰基坑内外水位差可能带来的基坑内渠坡抗浮和渗透破坏问题。鉴于此,在渠道渗控设计及围堰布置基础上,根据“前堵后排”思想,提出一种围堰基坑“外、中、内”三防线渗控方案,即围堰基坑外围渠基透水管封堵,基坑周边安装水泵抽排。三维渗流场模拟结果表明,该方案可显著降低基坑周边衬砌板下砂垫层内水平渗透比降和基坑涌水量,能保证基坑渗流安全。研究成果可为南水北调中线输水状态下挖方渠道围堰干地抢修提供理论依据和技术支持。 相似文献
73.
Ke Xu Zhenyun She Hongwei Wang Xingli Liu Yanyan Zhang Chengdeng Chi Hua Zhang 《International Journal of Food Science & Technology》2021,56(8):4081-4090
Effects of germination on components and structural changes of rice flours and, in turn, rheological properties and textural attributes of sweet dumplings were investigated in this study. Germination decreased starch, protein and lipid content, while slightly increased free amino acids content. Starch granular surface corroded, crystalline structure disrupted, and short-range ordered structures and helical structures decreased with germination. Moreover, germination resulted in a decreased paste viscosity and gel intensity of flour and a reduction of hardness and adhesiveness of dumplings. According to the Pearson’s correlation analysis, flours components and starch structures were significantly correlated with flours rheological properties that determined textural attributes of sweet dumplings. The germination contributed to significant changes in flours components and starch structures, which suggested the pretreatment of germination of waxy rice could be a promising pathway to control textural properties of sweet dumplings. 相似文献
74.
Jingjing Liu Wenlong Huo Bo Ren Ke Gan Yuju Lu Xiaoyan Zhang Xinyue Tang Jinlong Yang 《Ceramics International》2018,44(14):16751-16757
An innovative approach for fabricating porous alumina ceramics (PACs) with improved mechanical and thermal properties using walnut shell powders as pore-forming agent combined with alumina sol impregnation is reported in the present work. It is demonstrated that uniform distribution of spherical pores can be observed in as-prepared PACs by using above technical route. The decrease of walnut shell powder sizes significantly promotes the enhancement of crushing strength and reduction of thermal conductivity of the PACs. Meanwhile, the impregnated alumina sol is favoring for the formation of spherical micro-pores, then further improves their mechanical and thermal insulation performances. The lowest thermal conductivity and highest crushing strength of resulting sample reach 0.16?W/m?K and 29.2?MPa, respectively. This novel method offers new possibilities to fabricate high-quality PACs. 相似文献
75.
Recently, the rapid development of advanced communication systems increasingly strongly demands high-performance microwave dielectric ceramics in microwave circuits. Among them, Li2ZnTi3O8 ceramics have been one of the most widely investigated species, due to its high quality factor, moderate firing conditions and low cost. However, the dielectric constants of the already reported Li2ZnTi3O8 ceramics are fixed in a narrow range, limiting their wider applications. To adjust the dielectric constant of the Li2ZnTi3O8 based ceramics, in this work Li2ZnTi3O8 ceramics added with different amounts of Al2O3 (0–8?wt%) were prepared by conventional solid-state reaction. The microstructure and microwave dielectric properties of the samples were investigated. Due to the addition of Al2O3, the sintering temperature of the ceramics would be increased somewhat. Some Al3+ ions could substitute for Ti4+ ions in Li2ZnTi3O8, and the added Al2O3 would react with ZnO to produce a ZnAl2O4 phase accompanying with the formation of TiO2 phase, which would inhibit the growth of Li2ZnTi3O8 grains. The dielectric constant of the finally obtained ceramics would be reduced from 26.2 to 17.9, although the quality factors of the obtained ceramics would decrease somewhat and the temperature coefficient of resonant frequency would deviate further from zero. 相似文献
76.
Shanquan Chen Sicong Wei Fei Jin Shanming Ke Xierong Zeng Lang Chen Chuanwei Huang 《Ceramics International》2018,44(12):13695-13698
From the perspectives of scientific researches and practical applications, it is desirable to explore high operating temperature ferromagnetic films. The effect of biaxial strain on magnetic properties of (110)-oriented La0.7Sr0.3MnO3 films was studied. High quality La0.7Sr0.3MnO3 films were grown on (110)-oriented perovskite single crystal substrates using pulsed laser deposition, varying substrate-induced misfit strains from ??2.27–0.75%. A remarkable enhancement of Curie temperature has been achieved for (110)-oriented La0.7Sr0.3MnO3 films clamped with small misfit strains (i.e., grown on LAST (110)). The enhanced Curie temperature of (110)-oriented La0.7Sr0.3MnO3 films could be attributed to the misfit strain between the films and the underlying substrates and may have technological implication for applications at high temperature environments. 相似文献
77.
78.
Power Generation from Coke Oven Gas Using Chemical Looping Combustion: Thermodynamic Simulation 下载免费PDF全文
A chemical looping combustion (CLC) combined cycle with coke oven gas as fuel and NiO/NiAl2O4 as an oxygen carrier is proposed. The system was simulated by Aspen Plus® and the oxygen carrier circulation ratio was calculated. The effects of key operational temperatures and different gas turbines on the system performance were investigated. Under optimized conditions, a high CO2 capture efficiency could be achieved. To capture CO2 thoroughly, the PG6561B gas turbine can be employed, allowing for nearly 100 % CO2 capture efficiency. 相似文献
79.
Hongjun Zhang Hua Ke Huijiadai Luo Pengkang Guo Bin Yang Dechang Jia Yu Zhou 《Journal of the European Ceramic Society》2018,38(5):2353-2359
The 0.8Bi3.15Nd0.85Ti3O12 (BNdT)-0.2CoFe2O4 (CFO) composite multiferroic ceramics have been fabricated by spark plasma sintering (SPS) at 850?°C. The relative density of as-sintered SPS ceramic reaches 97.4 (±0.3)%. The composites are composed of pure BNdT and CFO phases without any preferred c-orientation. The a-orientation preference is more obvious perpendicular to the pressure direction. The average grain-sizes of BNdT and CFO are 163 and 146?nm, respectively. The BNdT phase has more grains below 100?nm (~20%). The super energy-dispersive X-ray analyses suggest no serious reaction between BNdT and CFO. The Raman spectrum verifies the nano-structure of the SPS ceramic via the broadening bands and peak shifts. The Curie temperature of the SPS ceramic declines to 560?°C with stabilized dielectric loss. The grain boundary resistance plays a dominant role on impedance above 700?°C. The remanent polarization approaches to 15.2?μC/cm2 (300?kV/cm) with lower coercive fields (?89/+95?kV/cm). 相似文献
80.
Tao Li Zehui Du Nobumichi Tamura Mao Ye Saikumar Inguva Wei Lu Xierong Zeng Shanming Ke Haitao Huang 《Journal of the European Ceramic Society》2018,38(4):1488-1497
(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (TC), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient. 相似文献