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11.
《Mechatronics》2022
A large-scale high-precision scan stage is important equipment in the industrial productions of micro-fabrication such as flat panel display (FPD) lithography systems. Designing controllers for multi-input multi-output (MIMO) systems is time-consuming and needs experience because of the interaction between each axis and many controller tuning parameters. The aim of this study is to develop a peak filter design method based on frequency response data to reduce repetitive disturbance. This data-based approach does not use the model and only uses the frequency response data of the controlled system and the disturbance spectrum calculated from the scanning error data (Contribution 1). The peak filter is designed by convex optimization and satisfies robust stability conditions for six-degree-of-freedom systems (Contribution 2). The control performance of the designed peak filter is experimentally demonstrated with an industrial MIMO large-scale high-precision scan stage in reducing the scanning error of the main stroke of the translation along the -axis (Contribution 3). 相似文献
12.
利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油,试验结果表明:沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s,残碳由7.16%降低至6.48%,实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成,沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响,从分子角度阐述空化改质重油的机理。研究结果表明:水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小;沥青质对低DBE化合物吸附性能降低;沥青质团聚体微晶结构更加松散;沥青质胶束粒度分布降低;沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能,改质处理后焦炭产率降低1.85个百分点,液体收率和气体产率分别增加1.52和0.33个百分点,水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。 相似文献
13.
《Ceramics International》2022,48(1):10-21
Pc-WLEDs are considered to play a spectacular role in future generation light sources in view of their outstanding energy efficiency. In this regard, Eu3+ activated BaY2ZnO5 phosphor was prepared and investigated by XRD, PL and SEM analyses. Rietveld refinement analysis was carried out to confirm the structure of the synthesized phosphor. The prepared phosphor shows an intense red emission around 627 nm under excitation by near UV light. The 5D0-7F2 transition intensity of the prepared phosphor is three times higher compared to the commercial (Y,Gd)BO3:Eu3+ red phosphor. The CIE colour coordinates of BaY2ZnO5:Eu3+ (9mol%) phosphor corresponds to be (0.6169, 0.3742) and it has a high 97.9 % colour purity. The obtained results reveal the utility of BaY2ZnO5:Eu3+ phosphor as an efficient red component in WLEDs, anti-counterfeiting and fingerprint detection applications. 相似文献
14.
《Ceramics International》2022,48(2):1889-1897
SiC fiber reinforced ceramic matrix composites (SiCf-CMCs) are considered to be one of the most promising materials in the electromagnetic (EM) stealth of aero-engines, which is expected to achieve strong absorption and broad-band performance. Multiscale structural design was applied to SiCf/Si3N4–SiOC composites by construction of micro/nanoscale heterogeneous interfaces and macro double-layer impedance matching structure. SiCf/Si3N4–SiOC composites were fabricated by using SiC fibers with different conductivities and SiOC–Si3N4 matrices with gradient impedance structures to improve impedance matching effectively. Owing to its unique structure, SiCf/Si3N4–SiOC composites (A3-composites) achieved excellent EM wave absorption performance with a minimum reflection coefficient (RCmin) of ?25.1 dB at 2.45 mm and an effective absorption bandwidth (EAB) of 4.0 GHz at 2.85 mm in X-band. Moreover, double-layer SiCf/Si3N4–SiOC with an improved impedance matching structure obtained an RCmin of ?56.9 dB and an EAB of 4.2 GHz at 3.00 mm, which means it can absorb more than 90% of the EM waves in the whole X-band. The RC is less than ?8 dB at 2.6–2.8 mm from RT to 600 °C in the whole X-band, displaying excellent high-temperature absorption performance. The results provide a new design opinion for broad-band EM absorbing SiCf-CMCs at high temperatures. 相似文献
15.
《International Journal of Hydrogen Energy》2022,47(73):31202-31222
Dark fermentation of sugarcane vinasse can be used as a “cleaning” step to remove sulfate prior to methanogenesis because sulfidogenic conditions can be successfully established in parallel with biohydrogen production. Using a 22 central composite rotational design (CCRD) and response surface methodology (RSM), this study assessed the impacts of bicarbonate and sulfate availability on the establishment of sulfidogenesis in the thermophilic (55 °C) fermentation of vinasse in batch reactors, equally assessing the impacts on biohydrogen evolution. CCRD-RSM results indicated the favoring of biohydrogen production at the lowest sulfate and bicarbonate concentrations, whilst the opposite was observed for sulfidogenesis. Glycerol, lactate, and hydrogen were the preferential electron donors utilized by sulfate-reducing bacteria (SRB), whilst ethanol was markedly consumed only at high sulfate concentrations. SRB were inhibited by sodium when dosing excess NaHCO3 and Na2SO4. Complementary tests revealed maximum biohydrogen production (2.40 mmol) out of the CCRD, at pH exceeding 7.5 with no interference of sulfidogenesis. Non-efficient biohydrogen production was observed at low pH (<5.0; ~1.90 mmol) because the uptake of lactate was inhibited. Meanwhile, homoacetogenesis was established under intermediate pH range (5.5–6.5), as revealed by the accumulation of acetate (up to 2.5 g L?1). 16S rRNA gene amplicon sequencing further revealed the genera Thermoanaerobacterium/Pseudoclostridium, Desulfotomaculum/Desulfohalotomaculum and Sporomusaceae/Moorella as the main biohydrogen-producing, sulfate-removing and biohydrogen-consuming (homoacetogens) microbial groups, respectively. Hence, using a single inoculum source, vinasse may provide a butyrate-rich (along with biohydrogen-rich biogas) or a sulfate-free and acetate-rich fermented effluent, depending mainly on proper pH control. 相似文献
16.
《Ceramics International》2022,48(6):8297-8305
Pure and Sn/Fe co-doped (0.2 at.% Sn and 0.6 at.% Fe, 0.6 at.% Sn and 0.2 at.% Fe, 1.0 at.% Sn and 1.0 at.% Fe) TiO2 nanoparticles were synthesized via a sol-gel method and subsequently calcined at different temperatures. Furthermore, the particles were analyzed by TG-DSC, XRD, TEM, HRTEM, EDS, SAED and UV–Vis for investigating the influences of dopant and calcination temperature on the thermal effect, composition, morphology, energy band gap (Eg) and the degradation efficiency of methyl orange (MO) under various light irradiations respectively. Results indicated that Sn/Fe co-doping inhibited the crystallization transformation from anatase to rutile phase of TiO2 and decreased the Eg. The increased calcination temperature and Sn/Fe co-doped effect brought about the abnormal grain growth of TiO2 nanoparticles. 0.6 at.% Sn/0.2 at.% Fe and 1.0 at.% Sn/1.0 at.% Fe co-doped TiO2 nanoparticles presented better photocatalytic performance than pure and 0.2 at.% Sn/0.6 at.% Fe co-doped TiO2 nanoparticles under visible light irradiation mainly due to the decreased Eg. On the contrary, 0.2 at.% Sn and 0.6 at.% Fe co-doped TiO2 nanoparticles calcined at 650 °C showed the most excellent photocatalytic performance under UV light irradiation, which was about twice as large as that of pure TiO2 possibly due to the formed hybrid structure of anatase and rutile phase as well as the h+-mediated decomposition pathway. 相似文献
17.
《Ceramics International》2022,48(8):10613-10619
Alumina ceramics with different unit numbers and gradient modes were prepared by digital light processing (DLP) 3D printing technology. The side length of each functional gradient structure was 10 mm, the porosity ratio was controlled to 70%, and the number of units were (1 × 1 × 1 unit) and (2 × 2 × 2 unit) respectively. The different gradient modes were named FCC, GFCC-1, GFCC-2 and GFCC-3. SEM, XRD, and other characterization methods proved that these gradient structures of alumina ceramics had only α-Al2O3 phase and good surface morphology. The mechanical properties and energy absorption properties of alumina ceramics with different functional gradient structures were studied by compression test. The results show that the gradient structure with 1 × 1 × 1 unit has better mechanical properties and energy absorption properties when the number of units is different. When the number of units is the same, GFCC-2 and GFCC-3 gradient structures have better compressive performance and energy absorption potential than FCC structures. The GFCC-2 gradient structure with 1 × 1 × 1 unit has a maximum compressive strength of 19.62 MPa and a maximum energy absorption value of 2.72 × 105 J/m3. The good performance of such functional gradient structures can provide new ideas for the design of lightweight and compressive energy absorption structures in the future. 相似文献
18.
《Advanced Powder Technology》2022,33(12):103879
Heat transfer within ceramic feedstock powders is still unclear, which impedes optimization of the thermal and mechanical properties of the thermal sprayed coatings. The microspheres (yttria-stabilized zirconia YSZ and lanthanum zirconate LZO) were prepared via the electro-spraying assisted phase inversion method (ESP). The thermal properties of the two ESP microspheres and a commercial hollow spherical powder (HOSP) were investigated by using theoretical, experimental, and simulation methods. Thermal conductivity of the single microsphere was estimated via a novel nest model that was derived from the Maxwell-Eucken 1 and the EMT model. Thermal conductivity of a single YSZ/LZO-ESP microsphere prepared at 1100–1200 °C was within 0.36–0.75 W/m K, which was ~ 20 % lower than that of a single YSZ-HOSP microsphere with a similar porosity. Heat flux simulation showed that high tortuosity around the multi-scaled voids of the ESP microsphere led to a more efficient decrease in thermal conductivity compared with total porosity. 相似文献
19.
20.
《International Journal of Hydrogen Energy》2022,47(44):18972-18982
The present study focused on the novel material with significantly improved properties for the application in the area of clean energy. The new complex oxide BaLaIn0·5Y0·5O4 with layered perovskite structure was obtained for the first time. It was proved that the introduction of Y3+ ions in the perovskite layer of BaLaInO4 leads i) to the rise of the oxygen-ionic conductivity due to the increase in mobility of oxygen ions as a result of the expand of the cell volume and ii) to the enhancement of protonic conductivity due to the increase in the proton concentration and mobility. The sample BaLaIn0·5Y0·5O4 is nearly pure proton conductor below 400 °C and has the protonic conductivity value 1.6?10?5 S/cm at this temperature. 相似文献