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排序方式: 共有651条查询结果,搜索用时 593 毫秒
641.
Akihide Kuwabara Xiang Gao Ralf Riedel Emanuel Ionescu Yuichi Ikuhara 《International Journal of Applied Ceramic Technology》2023,20(1):190-196
Transition-metal-doped silicon nitride ceramics have attracted much attention as gate materials for semiconductors because of their electrical properties as well as chemical and thermal stability. The present study aims to clarify the defect structures of Hf-doped β-Si3N4 by theoretical calculations and scanning transmission electron microscopy (STEM). First-principles calculations based on a hybrid functional method were performed. It was found that Hf dopants are mainly substituted for the Si sites and can be occasionally located at interstitial sites in the lattice of β-Si3N4. The substitution sites of Hf dopants predicted by the first-principles calculations were also confirmed by the high-resolution STEM images. 相似文献
642.
A review of stabilization methods for DCMG with CPL, the role of bandwidth limits and droop control 下载免费PDF全文
DC microgrids (DCMGs) integrate and coordinate various DC distribution generation units including various renewable energy sources and battery storage systems, and have been used in satellites, the International Space Station, telecom power stations, computer power supplies, electric aircraft, and electric ships. However, the presence of constant power loads (CPLs) can cause instability in DCMGs. Thus, this paper reviews the stabilization techniques that can resolve instability caused by CPLs, as well as various parameters of CPLs, such as bandwidth, and the frequency of the CPLs that can stabilize the DCMGs. It also discusses recent trends and future work in finding stability limits using the parameters of CPLs. It should be useful for directing research towards appropriate mathematical and experimental approaches for the stability of DCMGs with CPLs. 相似文献
643.
Model Identification and Control of Electromagnetic Actuation in Continuous Casting Process With Improved Quality 下载免费PDF全文
Isabela Birs Cristina Muresan Dana Copot Clara Ionescu 《IEEE/CAA Journal of Automatica Sinica》2023,10(1):203-215
This paper presents an original theoretical framework to model steel material properties in continuous casting line process. Specific properties arising from non-Newtonian dynamics are herein used to indicate the natural convergence of distributed parameter systems to fractional order transfer function models. Data driven identification from a real continuous casting line is used to identify model of the electromagnetic actuator device to control flow velocity of liquid steel. To ensure product specifications, a fractional order control is designed and validated on the system. A projection of the closed loop performance onto the quality assessment at end production line is also given in this paper. 相似文献
644.
Rémy Cochereau Viviana Maffeis Elena C. dos Santos Emanuel Lörtscher Cornelia G. Palivan 《Advanced functional materials》2023,33(48):2304782
Giant unilamellar vesicles (GUVs) are microcompartments serving to confine reactions, allow signaling pathways, or design synthetic cells. Polymer GUVs are composed of copolymer membranes mimicking cell membranes, and present advantages over lipid-based GUVs, such as higher mechanical stability and chemical versatility. Such microcompartments are essential for understanding reactions/signaling occurring in cells, which are difficult to study by in vivo approaches due to the cell's complexity. However, the lack of control over their production, stability, and membrane diffusion properties is still limiting their use for bio-related applications. Here, polymer GUVs produced by microfluidics and permeabilized with DNA-origami nanopores (DoNs) that present a high level of control over these essential properties are introduced. After systematic optimization of conditions, DoN-GUVs reveal a narrow size distribution, allow for high encapsulation efficiencies, and are stable for weeks, protecting encapsulated biomolecules. The kinetics of diffusion of molecules through the GUV's membrane is tuned by insertion of DoNs with a controlled 3D- structure. DNA polymerase I, encapsulated as model for bioreactions, successfully produced DNA duplex strands with spatiotemporal control. DoN-GUVs loaded with active molecules open new avenues in bioreactions, from the detection of biomolecules, over the tuning of molecular transport rates, to the investigation of cellular processes/signaling. 相似文献
645.
Alexander Baer Ingo Hoffmann Najet Mahmoudi Alexandre Poulhazan Matthew J. Harrington Georg Mayer Stephan Schmidt Emanuel Schneck 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2300516
For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins—the presumed building blocks of the fiber core—are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiber formation. 相似文献
646.
Rares Buta Emanuel Puschita Botond Sandor Kirei Cristian Codau Tudor Palade Paul Dolea Andra Pastrav 《International Journal of Satellite Communications and Networking》2023,41(5):477-498
The scope of this paper is to present the proof-of-concept and functional verification of a Wireless-SpaceWire bridge (High-Throughput Wireless-SpaceWire Bridge for Intra-Satellite Transmissions [HiSAT] bridge) designed to replace the wired SpaceWire (SpW) connections for intraspacecraft communications. To provide proper data handling and conversion, the proposed solution implements two main components: (1) the SpW Converter, which provides the SpW interface, and (2) the Wireless Converter, which provides the multiantenna radio frequency (RF) front-end. High-end research infrastructure is used in the solution implementation. STAR-Dundee SpW products emulate real spacecraft instrumentation and implement the SpW links and interfaces. Xilinx FPGA ZCU102 boards are used for the implementation of the hardware/software communication stack of the SpW Converter. A comprehensive National Instruments USRP Software Defined Radio platform is used to implement the Wireless Converter. End-to-end laboratory tests are run to evaluate the performance of the proposed solution in terms of average end-to-end delay, average data rate, and packet success rate and to assess the technology readiness. The results demonstrate that the HiSAT bridge is TRL4 and that the technological approach (i.e., using FPGAs and OFDM transmissions) can successfully replace an on-board intraspacecraft SpW link. 相似文献
647.
Soberanis M. A. Escalante Vales-Pinzón Caridad Hernández-Núñez Emanuel Flota-Bañuelos Manuel Medina J. Quintal-Palomo R. San-Pedro Liliana Ruiz-Gómez Miguel 《Clean Technologies and Environmental Policy》2023,25(1):35-49
Clean Technologies and Environmental Policy - Hydrogen (H2) is an energy carrier capable of replacing fossil fuels without the main effect of combustion-based pollutant generation into the... 相似文献
648.
Alexander Ott Johannes Peter Leonore Wiehl Vasily Potapkin Ulrike I. Kramm Hans-Joachim Kleebe Ralf Riedel Emanuel Ionescu 《International Journal of Applied Ceramic Technology》2022,19(2):838-846
Cellulose-based paper samples were surface-modified by a polymeric single-source precursor prepared from perhydropolysilazane (PHPS) and iron(III)acetylacetonate (Fe(acac)3) and ammonolyzed at 500°C, 700°C, 900°C, and 1000°C, leading to C/SiFe(N,C)O-based ceramic papers with in situ-generated hierarchical micro/nano-morphology. As reference, cellulose-free samples were prepared under the same conditions. Upon thermal treatment, the microstructure evolutions of the resulting ceramic paper and the reference sample were comparatively investigated. Scanning electron microscopy (SEM) showed that for all temperatures, the ceramic papers exhibit the same morphology as the template, however, with noticeable shrinkage and curling, particularly evident at higher temperatures. X-ray diffraction (XRD) measurements of the reference samples and the ceramic papers showed a similar crystallization behavior and phase evolution in both materials. In the ceramic paper, the crystallization process seems to occur at a later time. The results provide a comprehensive understanding of the investigated C/SiFe(N,C)O-based ceramic system. It was shown that use of the cellulose-based paper template has the benefit of retaining the microstructure and furthermore, apart from transforming the cellulose fibers into turbostratic carbon, does not change the phase evolution during the polymer-to-ceramic transformation, allowing at the same time the manufacturing of novel morphologically complex parts by a convenient one-pot synthesis approach. 相似文献
649.
From extraction experiments with 85Sr as a tracer, the extraction constant corresponding to the equilibrium Pb2+(aq) + SrL2+(nb) ⇄ PbL2+(nb) + Sr2+(aq) taking place in the two-phase water – nitrobenzene system (L = 18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(Pb2+, SrL2+) = 1.5. Further, the stability constant of the PbL2+ complex in nitrobenzene saturated with water was calculated: log βnb(PbL2+) = 12.9. 相似文献
650.
Emmanuel III Ricohermoso Eva Heripre Susana Solano-Arana Ralf Riedel Emanuel Ionescu 《International Journal of Applied Ceramic Technology》2023,20(2):735-746
Silicon oxycarbide film deposited on a silicon substrate has shown superior electrical conductivity relative to its monolithic counterpart. In this work, the evolution of different microstructures detected on the SiOC film reveals its hierarchical microstructure. The existence of sp2-hybridized carbon domains has been unambiguously confirmed by means of Raman spectroscopy and transmission electron microscopy corroborated with electron energy loss spectroscopy. The diffusion coefficient of carbon in silica and its dependence on temperature were studied by assessing energy-dispersive X-ray spectroscopy profiles taken from the cross-sections of samples annealed at temperatures in the range from 1100°C to 1400°C. The activation energy for diffusion of carbon in silica was determined to be approximately 3.05 eV, which is significantly lower than the values related to the self-diffusion of silicon and oxygen. The microstructural evolution of precursor to SiCnO4-n and SiC serves as migration path of sp2-hybridized carbon to the SiOx layer. With increasing temperature, the formation of microscale carbon-rich segregation is promoted while the SiOC film becomes thinner. 相似文献