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991.
研究了一类执行器饱和非线性Hamilton网络控制系统H∞状态反馈控制器设计问题。该类网络控制系统中存在不确定的网络时延及丢包,待设计的控制器受到饱和因素的约束,且系统的外部扰动范数有界但统计特性未知。结合Hamilton系统结构特性,当网络时延和连续丢包有界时,将网络时延和连续丢包转化为时变时滞,应用Lyapunov-Krasovskii稳定性理论来分析和设计H∞控制器,使其满足H∞性能指标,控制器中的未知参数通过求解不等式来确定。算例分析与仿真验证了方法的有效性。 相似文献
992.
海洋工程物探勘察中多种设备同时作业中常常遇到各种干扰现象,降低作业效率和资料质量,严重时造成作业失败、资料作废.本文将多种工程物探设备之间的干扰现象从船舶、电源、电磁和声学四方面进行分类,分别举例,分析干扰原因,针对各种类型的干扰提出了从理论和实践中总结出的的预防和解决方法,为其它作业中遭遇类似问题的处理提供理论支持和经验借鉴. 相似文献
993.
纳米TiO2碳热氮化制备纳米晶Ti(C0.7,N0.3)固溶体 总被引:1,自引:0,他引:1
在封闭系统中,对纳米TiO2碳热还原氮化反应合成纳米晶Ti(C,N)固溶体粉末进行研究。结果表明,当以C/Ti值为2.7配料,氮气压力为0.005 MPa时,一定量纳米TiO2/纳米碳黑混合料在1600℃下保温4 h,可以合成晶粒尺寸为32 nm的球形Ti(C0.7,N0.3)固溶体粉末。 相似文献
994.
采用水热共沉淀法和原位氧化还原法制备MnOx/MgAl类水滑石(Mg3Al1-LDHs)催化剂,以水玻璃作为黏结剂将其负载到铝蜂窝上,用于室温下去除甲醛。通过X射线衍射(XRD)、热重分析(TG)、X射线光电子能谱(XPS)、N2吸附-脱附、傅里叶变换红外光谱(FT-IR)等手段进行表征。表征结果表明:MnOx/Mg3Al1-LDHs具有典型类水滑石结构,大量结合水和羟基; MnOx为δ-MnO2和Mn3O4的混合物,具有高比例Mn4+/Mn3+和丰富的吸附氧。实验结果表明:室温(25 ℃,相对湿度60%)下反应4 h后,MnOx/Mg3Al1-LDHs催化剂可将甲醛质量浓度由1.30 mg/m3降至0.10 mg/m3以下,且经过8次和连续15 d实际测试,表明催化剂具有良好的稳定性和甲醛去除效果。MnOx/Mg3Al1-LDHs催化剂最佳负载量(质量分数)为5%,风扇最佳功率为10 W,空气中湿度对甲醛去除效果影响较小,该催化剂具有较强水分抵抗能力,反应温度提升会较大程度提高甲醛去除效果。 相似文献
995.
Niranjan Sitapure Hyeonggeon Lee Francisco Ospina-Acevedo Perla B. Balbuena Sungwon Hwang Joseph Sang-II Kwon 《American Institute of Chemical Engineers》2021,67(1):e17073
Li metal anode is the “Holy Grail” material of advanced Lithium-ion-batteries (LIBs). However, it is plagued by uncontrollable dendrite growth resulting in poor cycling efficiency and short-circuiting of batteries. This has spurred a plethora of research to understand the underlying mechanism of dendrite formation. While experimental studies suggest that there are complex physical and chemical interactions between heterogeneous solid-electrolyte interphase (SEI) and dendrite growth, most of the studies do not reveal the mechanisms triggering these interactions. To deal with this knowledge gap, we propose a multiscale modeling framework which couples kinetic Monte Carlo and Molecular Dynamics simulations. Specifically, the model has been developed to account for (a) heterogeneous SEI, (b) dendrite-SEI interactions, and (c) effect of electrolyte on Li electrodeposition and potential dendrite formation. This allows the proposed computational model to be extended to various electrolytes and SEI species and generate results consistent with previous experimental studies. 相似文献
996.
Numerical simulation of atomic layer deposition for thin deposit formation in a mesoporous substrate
Liwei Zhuang Peter Corkery Dennis T. Lee Seungjoon Lee Mahdi Kooshkbaghi Zhen-liang Xu Gance Dai Ioannis G. Kevrekidis Michael Tsapatsis 《American Institute of Chemical Engineers》2021,67(8):e17305
ZnO deposition in porous γ-Al2O3 via atomic layer deposition (ALD) is the critical first step for the fabrication of zeolitic imidazolate framework membranes using the ligand-induced perm-selectivation process (Science, 361 (2018), 1008–1011). A detailed computational fluid dynamics (CFD) model of the ALD reactor is developed using a finite-volume-based code and validated. It accounts for the transport processes within the feeding system and reaction chamber. The simulated precursor spatiotemporal profiles assuming no ALD reaction were used as boundary conditions in modeling diethylzinc reaction/diffusion in porous γ-Al2O3, the predictions of which agreed with experimental electron microscopy measurements. Further simulations confirmed that the present deposition flux is much less than the upper limit of flux, below which the decoupling of reactor/substrate is an accurate assumption. The modeling approach demonstrated here allows for the design of ALD processes for thin-film membrane formation including the synthesis of metal–organic framework membranes. 相似文献
997.
Jin Xu Tingting Zang Ding Du Sandeep Kumar Moolchand Sharma Rahul Vaish 《Journal of the American Ceramic Society》2021,104(4):1661-1668
The BaTiO3 powder was prepared via a solid-state reaction route. It was studied for the degradation of bacterial cells, dye, and pharmaceuticals waste using ultrasonically driven piezocatalytic effect. The bacterial catalytic behavior of poled BaTiO3 was remarkably increased during ultrasonication (10% E coli survival in 60 minutes). The structural damages were illustrated using scanning electron micrographs of bacterial cells which demonstrated morphological manifestations under different conditions. Methylene blue (MB dye), ciprofloxacin and diclofenac were also cleaned using the piezocatalytic effect associated with the poled BaTiO3 powder. Around 92, 85, and 78% of degradations were observed within 150 minutes duration for methylene blue, ciprofloxacin, and diclofenac, respectively. 相似文献
998.
This work was done to assess the role of precursors (agro and graphite) on performance of carbon nanoallotropes-biomacromolecules composite as drug delivery for controlling the release of niacin. In this respect graphene oxide and bagasse-based carbon oxide were synthesized and chelated with chitosan (Cs-GO and Cs-Co). These gel composites were characterized by many techniques [morphology, differential scanning calorimetry, Fourier-transform infrared spectroscopy, swelling, encapsulation efficiency (EE) and loading (L) % of niacin. Another series of experiments was carried out for studying the role of replacing part of carbon nanoallotrope by carboxymethyl cellulose (CMC) on performance of produced drug carries, these systems were coded as Cs-GO-CMC and Cs-Co-CMC. The data showed that, the Cs-GO gel composite provided maximum release of NA, at 5 h, for pH's simulated gastric and intestinal fluids; pH. 2.1 and pH 7.4 (1120 mg/L and 757 mg/L). The incorporation of CMC is not acceptable as it provided low drug release together with burst release of NA-drug, and consequently possible caused tissue irritation or toxicity in the human body. The Cs-GO and Cs-CO systems with relatively low drug loading were recommended for their better controllability system to NA release, which prolonging benefit of human with niacin. The NA release from all investigated gels followed Fickian and non-Fickian diffusion mechanisms. 相似文献
999.
Soubhik De P.N. Shivangi Saswat Choudhury Abhinav Omprakash Fulmali Bankim Chandra Ray Rajesh Kumar Prusty 《应用聚合物科学杂志》2021,138(42):51231
Carbon fiber reinforced epoxy (CE) composite is ideal for a cryogenic fuel storage tank in space applications due to its unmatched specific strength and modulus. In this article, inter-laminar shear strength (ILSS) of carbon fiber/epoxy (CE) composite is shown to be considerably improved by engineering the interface with carboxyl functionalized multi-walled carbon nanotube (FCNT) using electrophoretic deposition technique. FCNT deposited fibers from different bath concentrations (0.3, 0.5, and 1.0 g/L) were used to fabricate the laminates, which were then tested at room (30°C) and in-situ liquid nitrogen (LN) (−196°C) temperature as well as conditioning for different time durations (0.25, 0.5, 1, 6, and 12 h) followed by immediate RT testing to study the applicability of these engineered materials at the cryogenic environment. A maximum increment in ILSS was noticed at bath concentration of 0.5 g/L, which was ~21% and ~ 17% higher than neat composite at 30°C and − 196°C, respectively. Short-term LN conditioning was found to be detrimental due to developed cryogenic shock, which was further found to be compensated by cryogenic interfacial clamping upon long-term exposure. 相似文献
1000.
Hollow spheres of nickel oxide (NiO) and silver, gold, and platinum nanoparticle loaded NiO composites were successfully produced by using polystyrene (PS) latexes as hard template. Due to the presence of tertiary amine based diblock copolymer stabilizer on the surface of PS, the tertiary amine functional groups provided homogene deposition of nickel hydroxide, and then the precursor NiO salt production on the surface of PS latexes with a controlled precipitation technique. Then, NiO and NiO/metal NP hollow spheres were produced by calcination at 600 °C. Thermogravimetric analysis indicated that the amounts of NiO and NiO-composite after calcination were in the range of 21.1–29.7 wt%. The diameters of metal oxide spheres were in the range of 2.0–2.7 μm and the shell thickness were in the range of 250–350 nm. These structures had very low densities due to their porous and hollow structures and had outer layers with highly rough surfaces due to formation of nanosheets, which may offer important advantages for catalysis studies. 相似文献