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941.
介绍了超导托克马克聚变实验装置中加速极电源系统的光纤监控网络;为了保证电源系统的安全和稳定,必须对各电源模块的状态进行实时监控;对高电压、强电磁干扰环境中的光纤监控网络进行了软、硬件设计,通过模拟调试。给当了系统在传输速度为9600bps时的通讯时间和复位时间,证实了该方法的可行性。 相似文献
942.
一个求解次短和渐次短路径的实用算法 总被引:1,自引:0,他引:1
求解第k短路径问题在决策支持系统和咨询系统中具有广泛的用途,本文基于Dijkstra算法,给出了一个求解次短路径和渐次短路径的算法,并且分析了算法的时间复杂度和空间复杂度。 相似文献
943.
In the present study, flow homogenization by distributors in chemical apparatus is studied as a process of flow control and its mechanism is reconsidered from the model of resistance to the model of radial flow. This process is composed of four consecutive behaviors: the generation, distribution, conversion of the radial flow and the momentum transfer of axial flow. Based on these flow behaviors, the novel distributor is designed as the combination of perforated plate in the center area and vertical guiding baffles around. Taking the wire-screen catalytic reactor as a case study, numerical simulation is employed to optimize the structure of distributor and a CFD-based design scheme called “flow field analysis scheme” is proposed. Numerical simulation is conducted in the apparatus with a diffuser (inlet D0 = 500 mm, main part D1 = 3,000 mm) under the gas velocity of 3.6 m/s (corresponding Re ≈ 12,000). The numerical results from optimized distributor show that compared with the traditional perforated plate, the flow field adjusted by the novel distributor can achieve a better flow uniformity with lower energy consumption. The theoretical analysis and numerical results are also validated and proved by the experimental results. 相似文献
944.
Pengju Chen Peng Xiao Zhuan Li Ling Pan Jinwei Li Zeyan Liu Dongmei Pu Yang Li 《Journal of the American Ceramic Society》2020,103(1):82-93
Mullite coating, SiC whiskers toughened mullite coating (SiCw-mullite), and cristobalite aluminum phosphate (c-AlPO4) particle modified SiCw-mullite coating (c-AlPO4-SiCw-mullite) were prepared on SiC coated C/SiC composites using a novel sol-gel method combined with air spraying. Results show that molten SiO2 formed by the oxidation of SiC whiskers and molten c-AlPO4 improved the bonding strength between mullite outer coating and SiC–C/SiC composites due to their high-temperature bonding properties. The bonding strength between mullite, SiCw-mullite, c-AlPO4-SiCw-mullite outer coatings and SiC–C/SiC composites were 2.41, 4.31, and 7.38 MPa, respectively. After 48 thermal cycles between 1773 K and room temperature, the weight loss of mullite/SiC coating coated C/SiC composites was up to 11.61%, while the weight losses of SiCw-mullite/SiC and c-AlPO4-SiCw-mullite/SiC coatings coated C/SiC composites were reduced to 7.40% and 5.12%, respectively. The addition of appropriate SiC whiskers can considerably improve the thermal shock resistance of mullite coating owing to their excellent mechanical properties at high temperature. In addition, c-AlPO4 particles can further improve the thermal shock resistance of SiCw-mullite coating due to their high-temperature bonding and sealing properties. No obvious micro-pores and cracks were observed on the surface of c-AlPO4-SiCw-mullite coating after 48 thermal cycles due to timely healing effect by formation of secondary mullite. 相似文献
945.
Wengao Pan Minghe Cao Hua Hao Zhonghua Yao Zhiyong Yu Hanxing Liu 《Journal of the American Ceramic Society》2020,103(11):6298-6307
Defect chemistry of Sr site nonstoichiometry in SrxTi0.985(Nb2/3Zn1/3)0.015O3 ceramics and the resulting effects on the structure and dielectric behavior are systematically investigated by experiment and density functional theory (DFT) methods. The results indicate that, appropriate Sr deficiency benefits the dielectric properties and grain growth due to the creation of Sr vacancy. While Sr excess deteriorates the dielectric properties and inhibits the grain growth by forming a Ruddlesden-Popper structure. In Sr-deficient sample, more point defects arise and aggregate into defect clusters, resulting in great changes in local structures and the enhancement of dielectric properties. The Sr vacancy benefits the generation of oxygen vacancy, thus facilitating the localization of electrons and the decrease in dielectric loss. Besides, the electronic polarization and structural polarization are also improved by Sr vacancy and the resultant oxygen vacancy, leading to the further enhanced dielectric properties. These findings may facilitate the development of defect engineering towards novel multifunctional electronic materials. 相似文献
946.
Jing Cheng Yan Xing Ziyuan Wang Xiaohui Zhao XiQiang Zhong Wei Pan 《Journal of the American Ceramic Society》2020,103(5):2975-2978
Mo2N/MoO2 composite nanofibers have been prepared via an electrospinning and controlled nitridation process. The composite nanofibers exhibit a highly efficient Rhodamine B (RhB) absorption behavior with a rate constant of 0.153 g min−1 mg−1, which is about 20 times of the commercial-activated carbon material. Furthermore, the nanofibers show stable absorption activity after recycled by an environmental friendly procedure for four times. The excellent absorption performance of Mo2N/MoO2 composite nanofibers demonstrates a promising application of Mo2N-related materials as an absorbent for wastewater treatment. 相似文献
947.
Wujie Zhang Xiangjun Li Muhammad A. Nawaz Jiahao Pan Jiancheng Cao Dianhua Liu 《加拿大化工杂志》2020,98(5):1148-1156
Polyoxymethylene dimethyl ethers (PODEn) are extremely effective diesel additives to reduce soot formation during combustion. We introduce a series of Fe-Zn composite solid acid catalysts (SO42−/xFe2O3-yZnO), for the condensation reaction of methanol and paraformaldehyde (PF) with a cheap and feasible route to efficiently synthesize PODEn. These catalysts were characterized by different characterization techniques, namely BET, XRD, SEM, EDS, FTIR, and NH3-TPD and the results showed that Fe/Zn molar ratios strongly influenced the physicochemical characteristics of catalysts, thus affecting the methanol conversion and PODE1-6 and PODE3-6 selectivity. Accordingly, the methanol conversion was decreased and the selectivity of PODE3-6 was increased after increasing the Zn molar content. Comparatively, SO42−/Fe2O3-2ZnO exhibited superior catalytic activity among the various investigated catalysts due to the high acid density of strong acid sites. The optimal reaction conditions were observed to be at a 3.0 wt% catalyst loading (catalyst/reactant mass ratio), 2.5 hours ours of reaction time, a reaction temperature of 403 K, and a molar ratio of 3:1 of CH2O to methanol, achieving a high selectivity of 99.09% PODE1-6 and 28.23% PODE3-6 with 55.16% methanol conversion during the reaction. 相似文献
948.
A multistep processing method was developed to fabricate a partial wetting morphology for improving toughness of flame retardant polymer. In the first step, high-density polyethylene (HDPE) and nylon 6 (PA6) were melt-extruded with intumescent flame retardant (IFR) for fabricating HDPE/PA6/IFR blends with a core–shell structure (core: IFR, shell: PA6). At the second step, maleic anhydride-grafted-linear low-density polyethylene (LLDPE-g-MAH) was melted with HDPE/PA6/IFR at processing temperatures slightly below the melting temperature of PA6 to produce a partial wetting morphology in which LLDPE-g-MAH phase with the sphere was dispersed at the HDPE/PA6 interface. The effect of the LLDPE-g-MAH content on the impact strength was investigated, and high toughness was exhibited in the blend with 2 wt % LLDPE-g-MAH. Its elongation at break and notched impact strength were 43 and 270% higher, respectively, than that of neat HDPE. The unique interface failure mode was responsible for the high impact strength. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48735. 相似文献
949.
Dan Meng Jiazhuo Xie Geoffrey I. N. Waterhouse Kun Zhang Qinghua Zhao Shuo Wang Shuo Qiu Kaijun Chen Jinxi Li Chizhen Ma Yue Pan Jing Xu 《应用聚合物科学杂志》2020,137(12):48485
The accumulation of nonbiodegradable petrochemical-based polymers in the environment motivates the development and use of low-cost, eco-friendly, and biodegradable polymers. A series of biodegradable poly(butylene adipate-co-terephthalate) composites reinforced by sustainably sourced nanochitin were successfully prepared using melt blending and compression molding methods. Structural, thermal, and mechanical characterizations of poly(butylene adipate-co-terephthalate) (PBAT)/nanochitin composites were performed. SEM revealed that the nanochitin was uniformly dispersed throughout the PBAT matrix at low contents (<2 wt %), while DSC analyses revealed a corresponding increase in the crystallinity (32.6% enhancement) of the PBAT matrix. The tensile strength and elongation at break of the PBAT/nanochitin composite containing 0.5 wt % nanochitin were higher by 82.5 and 64.2%, respectively, compared with pristine PBAT. The Chitin-0.5 composite also showed improved thermal stability compared with PBAT (the char yield improved by 8%) due to the uniform dispersion of nanochitin in the PBAT matrix. The enhanced performance of the PBAT/nanochitin composites, prepared without an added compatibilizer, informs the development of improved biodegradable PBAT-based polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48485. 相似文献
950.