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991.
建立了冷凝热利用热力学分析模型,根据热力学分析结果,确定冷凝温度、热水温度为影响冷凝热利用的关键因素.分析了影响因素变化时冷凝热利用的能效情况.结果表明,当冷凝温度达到40℃以上时,可获得接近50℃的热水,但此时机组的制冷能效将低于4.0.提出了结合机组能效确定热水温度的优化方法,优化得到的最佳热水设定温度范围为50~54℃,此时机组制冷能效大于4.5,综合能效大于5.6. 相似文献
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用粒径1.18~5.00mm,600μm~1.18mm,300~600μm和<300μm这4种废玻璃分别取代(质量分数)30%,60%,100%天然砂配制砂浆,测试砂浆在20,300,400,600,800,900℃的抗压强度和劈裂抗拉强度.结果表明:在常温下,用粒径≥300μm废玻璃取代天然砂后,砂浆强度低于基准砂浆,且随废玻璃取代率增大而降低;用粒径<300μm的废玻璃取代部分天然砂后,砂浆劈裂抗拉强度略大于基准砂浆,抗压强度则大大高于基准砂浆;所有配合比砂浆强度均随着加热温度的提高不断降低,强度与加热温度间呈良好的线性关系,相关系数大多>0.980;用粒径<300μm废玻璃取代60%以上天然砂,高温益化系数>1.25,可显著提高砂浆的高温性能. 相似文献
993.
广州骑楼是具有自身性格特征的一道建筑景观,它凝聚着清末民初时期的政治、历史、经济和文化,体现着古今文化和中西文化的兼容并蓄.今以广州骑楼的历史文化演变为切入口,从建筑符号学的角度分析广州骑楼的内结构和外结构的符号特征,挖掘出其符号精神内涵,使之与现代设计相结合,实现可持续发展. 相似文献
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Synthesis and characterization of a novel fluorene‐alt‐carbazole polymer to host green,blue, and red phosphorescence 下载免费PDF全文
A novel fluorene‐alt‐carbazole polymer host Poly(9,9‐dioctyl‐9H‐fluorene‐2,7‐diyl‐alt‐N‐tetrahydropyran‐3,6‐carbazole) (PFCz), composed of N‐tetrahydropyran‐3,6‐carbazole and 9,9‐dioctyl‐2,7‐fluorene in the polymer backbone, was synthesized by Suzuki coupling. The PFCz possesses good thermal stability and proper lowest unoccupied molecular orbital (LUMO)/highest occupied molecular orbital (HOMO) energy levels to facilitate the injection and transport of electrons and holes. Upon doping with blue, green, and red phosphors, red ‐ green ‐ blue (R‐G‐B) phosphorescent devices hosted by PFCz have been fabricated and investigated. In contrast to those of blue and green devices, the red devices give better performances with a maximum luminous efficiency of 4.88 cd/A and a maximum power efficiency of 1.85% at 149.84 cd/m2, due to favorable triplet energy level (ET) of PFCz for red phosphor, bis(2‐methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(III) [Ir(MDQ)2(acac)]. Additionally, with different doped concentrations of Ir(MDQ)2(acac), the PFCz‐related red devices emit nearly pure red light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.57, 0.38), (0.60, 0.38), (0.61, 0.38), and (0.62, 0.38), which were very close to the standard red (0.66, 0.34) by the National Television System Committee. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43234. 相似文献
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Functional modification of poly(vinyl alcohol) by copolymerizing with a hydrophobic cationic double alkyl‐substituted monomer 下载免费PDF全文
In this paper, a hydrophobic monomer (HM) that has a cationic double alkyl‐substituted group bonded to the nitrogen atom was first synthesized. Then a hydrophobic poly(vinyl alcohol) (PVA) was prepared by a radical solution copolymerization of vinyl acetate (VAc) with the HM followed by an alcoholysis reaction in alkaline conditions. The structures of HM and hydrophobically modified PVA (H‐PVA) were confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The effect of hydrophobic cationic segments on crystallization behaviors, mechanical properties, morphology, solution viscosity, and hydrophobic property were investigated. The results indicated that the crystallinity decreased from 37.2% of pure PVA to the minimum 23.2% of H‐PVA with the incorporation of 1.15 mol % HM. The thermal decomposition temperature of H‐PVA increased by about 50 °C compared with that of pure PVA. The viscosity of the H‐PVA solution was several times higher than that of the corresponding unmodified PVA solution over the whole shear rate range, which demonstrated that the H‐PVA had good shear‐resistance ability. Furthermore, the contact angle was significantly increased from 55.1° to 115° with the incorporation of only 0.83% HM, which illustrated that the H‐PVA had high hydrophobicity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43888. 相似文献
1000.
Determination of trace macrolide antibiotics in milk with online solid‐phase extraction with an ionic‐liquid‐based monolithic column 下载免费PDF全文
An ionic liquid (IL)‐based monolithic poly(ionic liquid glycidylmethacrylate‐co‐ethylene glycol dimethacrylate) column was prepared via in situ free‐radical polymerization with 1‐vinyl‐3‐butylimidazolium chlorine as one of the comonomers. The obtained monolithic column was used as the sorbent of solid‐phase extraction (SPE) and coupled with high‐performance liquid chromatography for the simultaneous determination of the macrolide antibiotics roxithromycin (ROX) and acetylspiramycin (ACE) in processed pure milk. The monolithic column was characterized by Fourier transform infrared spectrometry, scanning electron microscopy, nitrogen absorption–desorption, mercury intrusion porosimetry, and thermogravimetric analysis. The results reveal that the monolithic column exhibited a high selectivity and good permeability to the macrolide antibiotics in milk. The optimized method offered excellent linearity with a linear regression coefficient greater than 0.998. The precisions for interday and intraday were both less than 7.7%. The accuracies expressed by the recoveries for ROX and ACE were in the ranges 92.5–103.8 and 93.0–107.6%, respectively. Compared to the previous methods, this method had a low limit of detection and a good accuracy. As a result, the polymer IL based monolithic column could feasibly be used as a high‐selectivity online SPE sorbent for determining trace macrolide antibiotics in milk. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43943. 相似文献