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排序方式： 共有775条查询结果，搜索用时 0 毫秒
71.
This paper deals with pool boiling of water–Al2O3 and water–Cu nanofluids on porous coated, horizontal tubes. Commercially available stainless-steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate a test heater. Aluminum porous coatings 0.15 mm thick with porosity of about 40% were produced by plasma spraying. A smooth tube served as a reference tube. The experiments were conducted under different absolute operating pressures of 200 kPa, 100 kPa, and 10 kPa. Nanoparticles were tested at concentrations of 0.01%, 0.1%, and 1% by weight. In all cases tested, enhancement heat transfer was always observed during boiling of water–Al2O3 and water–Cu nanofluids on smooth tubes compared to boiling of distilled water. Contrary to smooth tubes, addition of even a small amount of nanoparticles resulted in deterioration of heat transfer during pool boiling of water–Al2O3 and water–Cu nanofluids on porous coated tubes in comparison with boiling of distilled water. 相似文献
72.
Janusz Jankowski 《热应力杂志》2013,36(9):965-992
ABSTRACT The work includes a proposal of solving coupled quasi-static problems of linear thermoelasticity with coupled initial state by Helmholtz potentials. The proposal is based on an extension of the body region to the whole space where the space integral as a particular solution of the Helmholtz initial-boundary value problem is derived. Thermomechanical fictitious sources are separated from the space integral. Their capacities are determined on an approximate way from the boundary conditions in a bounded time interval. The approximated solution of the initial-boundary value problem of thermoelasticity was obtained by contraction of the space integral in space and time. 相似文献
73.
74.
Jacek Biesiada Janusz Zieliński 《Journal of Superconductivity and Novel Magnetism》1997,10(5):513-517
The anisotropic superconductivity has been considered in the two-dimensional Hubbard model. We allow for on and off-site intralayer
Cooper pairs. Interlayer momentum-conserving Josephson tunneling which couples adjacent layers has been taken into account.
The meanfield solution for the superconducting transition temperature demonstrates the competition between local Coulomb repulsion
and interlayer tunneling in thes-wave channel. This competition leads to the mixedsd superconducting state at low doping. We also demonstrate thatc-phonon-assisted transitions between intra and interlayer states can effectively give rise to momentum-conserving Josephson
tunneling. 相似文献
75.
Janusz Adamiec 《Drying Technology》2002,20(4):839-853
Sludge wastes are a very attractive source of many valuable compounds such as nitrogen, phosphorus and organic matter. One of the interesting methods of sludge utilization is dewatering and drying. In this paper some problems of drying of two types of sludge wastes of different form and origin are presented. One of the sludges—a brewery by-product— contains spent grain suspension of brewer's yeast and diatomaceous earth. The second one is a by-product of a biotechnological process which contains mainly lime, protein, many microelements and some microorganisms. Moisture content of both sludges is about 65-70% w/w. The laboratory experiments of sludge drying in the fluidized bed dryer with a mixer, fluidized bed hydrodynamics, and the effects and advantages of sludge drying are shown. 相似文献
76.
Polyurethane (PU) recycling is a topic of growing interest due to the increasing amount of polyurethane waste. The main purpose of polyurethane chemical recycling is to recover the starting polyol. In this study, a method of polyurethane thermochemical recycling, glycerolysis by means of crude glycerin, is proposed. This work presents a comparative study of commercial catalysts used in order to accelerate the decomposition process, namely triethylamine (TEA), potassium acetate (KAc), 1,4‐diazabicyclo[2.2.2]octane (DABCO), sodium hydroxide (NaOH), dibutyltin dilaurate (DbDl), and stannous octoate (StOc).The effect of used catalyst on the chemical structure and rheological properties was studied. The type of catalyst does not have significant influence on the chemical structure, but causes different course of reaction: split‐ and single‐phase in applied conditions. Glycerolysates were measured by Brookfield Rheometer. It was found that repolyols can be described by the Herschel–Bulkely mathematical model in the best accuracy. The investigation showed that the rheological behavior of glycerolysates depended on the catalyst used in glycerolysis process. POLYM. ENG. SCI., 57:891–900, 2017. © 2016 Society of Plastics Engineers 相似文献
77.
78.
Haris Balta Janusz Bedkowski Shashank Govindaraj Karol Majek Pawel Musialik Daniel Serrano Kostas Alexis Roland Siegwart Geert De Cubber 《野外机器人技术杂志》2017,34(3):539-582
Search‐and‐rescue operations have recently been confronted with the introduction of robotic tools that assist the human search‐and‐rescue workers in their dangerous but life‐saving job of searching for human survivors after major catastrophes. However, the world of search and rescue is highly reliant on strict procedures for the transfer of messages, alarms, data, and command and control over the deployed assets. The introduction of robotic tools into this world causes an important structural change in this procedural toolchain. Moreover, the introduction of search‐and‐rescue robots acting as data gatherers could potentially lead to an information overload toward the human search‐and‐rescue workers, if the data acquired by these robotic tools are not managed in an intelligent way. With that in mind, we present in this paper an integrated data combination and data management architecture that is able to accommodate real‐time data gathered by a fleet of robotic vehicles on a crisis site, and we present and publish these data in a way that is easy to understand by end‐users. In the scope of this paper, a fleet of unmanned ground and aerial search‐and‐rescue vehicles is considered, developed within the scope of the European ICARUS project. As a first step toward the integrated data‐management methodology, the different robotic systems require an interoperable framework in order to pass data from one to another and toward the unified command and control station. As a second step, a data fusion methodology will be presented, combining the data acquired by the different heterogenic robotic systems. The computation needed for this process is done in a novel mobile data center and then (as a third step) published in a software as a service (SaaS) model. The SaaS model helps in providing access to robotic data over ubiquitous Ethernet connections. As a final step, we show how the presented data‐management architecture allows for reusing recorded exercises with real robots and rescue teams for training purposes and teaching search‐and‐rescue personnel how to handle the different robotic tools. The system was validated in two experiments. First, in the controlled environment of a military testing base, a fleet of unmanned ground and aerial vehicles was deployed in an earthquake‐response scenario. The data gathered by the different interoperable robotic systems were combined by a novel mobile data center and presented to the end‐user public. Second, an unmanned aerial system was deployed on an actual mission with an international relief team to help with the relief operations after major flooding in Bosnia in the spring of 2014. Due to the nature of the event (floods), no ground vehicles were deployed here, but all data acquired by the aerial system (mainly three‐dimensional maps) were stored in the ICARUS data center, where they were securely published for authorized personnel all over the world. This mission (which is, to our knowledge, the first recorded deployment of an unmanned aerial system by an official governmental international search‐and‐rescue team in another country) proved also the concept of the procedural integration of the ICARUS data management system into the existing procedural toolchain of the search and rescue workers, and this in an international context (deployment from Belgium to Bosnia). The feedback received from the search‐and‐rescue personnel on both validation exercises was highly positive, proving that the ICARUS data management system can efficiently increase the situational awareness of the search‐and‐rescue personnel. 相似文献
79.
Michał Terlecki Saumya Badoni Michał K. Leszczyński Stanisław Gierlotka Iwona Justyniak Hanako Okuno Małgorzata Wolska-Pietkiewicz Daniel Lee Gaël De Paëpe Janusz Lewiński 《Advanced functional materials》2021,31(49):2105318
Colloidal nanoplatelets (NPLs) and nanosheets with controlled thickness have recently emerged as an exciting new class of quantum-sized nanomaterials with substantially distinct optical properties compared to 0D quantum dots. Zn-based NPLs are an attractive heavy-metal-free alternative to the so far most widespread cadmium chalcogenide colloidal 2D semiconductor nanostructures, but their synthesis remains challenging to achieve. The authors describe herein, to the best of their knowledge, the first synthesis of highly stable ZnO NPLs with the atomically precise thickness, which for the smallest NPLs is 3.2 nm (corresponding to 12 ZnO layers). Furthermore, by means of dynamic nuclear polarization-enhanced solid-state 15N NMR, the original role of the benzamidine ligands in stabilizing the surface of these nanomaterials is revealed, which can bind to both the polar and non-polar ZnO facets, acting either as X- or L-type ligands, respectively. This bimodal stabilization allows obtaining hexagonal NPLs for which the surface energy of the facets is modulated by the presence of the ligands. Thus, in-depth study of the interactions at the organic–inorganic interfaces provides a deeper understanding of the ligand–surface interface and should facilitate the future chemistry of stable-by-design nano-objects. 相似文献
80.
The cycloaddition of CO2 to epoxides represents a green efficient method to form bis(cyclic carbonate)s. The main purpose of the work reported in this paper was to examine the effect of the gas flow rate (20, 40, 60 and 100 mL min–1) during carbonation on the conversion yield, chemical structure, rheological behaviour and thermal properties of the prepared compounds. A series of new bis(cyclic carbonate)s was obtained from bio‐based polyether polyol. The syntheses were performed in the absence of toxic solvents and the process did not require the use of elevated pressure. The progressive structural changes and the presence of characteristic chemical groups were monitored by attenuated total reflection Fourier transform infrared spectroscopy. The characterization of the structure by 1H NMR and 13C NMR also confirmed the formation of cyclic carbonate moieties. The non‐Newtonian behaviour and the optimal mathematical model (Herschel–Bulkley) were verified by rheological measurements. The materials obtained could be used as a chemical intermediate to synthesize advanced materials based upon polyurethanes without using isocyanates. © 2019 Society of Chemical Industry 相似文献