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排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
We have developed an electronic classroom environment based on an analog/digital hybrid network, ComWeb. This environment supplements traditional methods of presentation by providing powerful communication tools between the students and the teacher directed from the instructor's workstation. The instructor can access every student's workstation at any time to monitor the student's work or to transmit information from any source. ComWeb has facilities for individual and group supervision. It can be adapted for teaching deaf or hard of hearing students in a mainstream environment. We describe the implementation of a ComWeb-based classroom at our site. The performance of students in conventional sections of a computer literacy course is compared with that in a section using ComWeb. For most of the material, performance of students in the ComWeb based section was markedly superior. 相似文献
2.
A new empirico-statistical model is suggested to distinguish dependent narrative texts from independent narrative texts by means of their volume functions. A regard for information principle and an amplitude correlation principle are formulated. The model and both principles are examined experimentally using specific historical texts.Anatoliy T. Fomenko (Dr. Sci. in mathematics, Lomonosov State University) is a Professor at Lomonosov State University, Moscow. He is author of twelve monographs and textbooks, and is co-author of the two-volume Modern Geometry (Springer-Verlag). He is also artist and historian.Svetlozar T. Rachev (Dr. Sci., Steklov Mathematical Institute) is a Professor at the University of California, Santa Barbara. He has published more than seventy papers and is co-author of the monographMathematical Models for Construction of Queuing Models (Moscow, 1988). His main interests are: stability of stochastic models, theory of probability metrics, queuing theory and survival models. 相似文献
3.
Agrawal Prateek Chaudhary Deepak Madaan Vishu Zabrovskiy Anatoliy Prodan Radu Kimovski Dragi Timmerer Christian 《Multimedia Tools and Applications》2021,80(4):5319-5350
Multimedia Tools and Applications - Automated bank cheque verification using image processing is an attempt to complement the present cheque truncation system, as well as to provide an alternate... 相似文献
4.
Vladimir Aniskin Sergey Mironov Anatoliy Maslov 《Microfluidics and nanofluidics》2013,14(3-4):605-614
Results of research on microjets escaping into an ambient space from nozzles with diameters of 341–10.4 μm are described. A special Pitot microtube is used for studying the structure of supersonic microjets. The main feature of this microtube is a small diameter of the intake hole (12 μm). The main parameters of supersonic underexpanded microjets are identified, including the size of shock cells and the supersonic core length of the microjet. The results show a significant increase in the supersonic core length of microjets compared to macrojets. The Reynolds numbers of the laminar–turbulent transition in microjets are found to be in the range of 1,100–2,100. In addition, a classification of supersonic underexpanded axisymmetric microjets escaping into the ambient space is proposed. 相似文献
5.
Yuli D. Chashechkin Vasiliy G. Baydulov Anatoliy V. Kistovich 《Journal of Engineering Mathematics》2006,55(1-4):313-338
Results of analytical studies of the governing equations of stratified rotating fluids based on the unification of theories
of continuous and discrete groups, perturbations and modern numerical visualizations are described. Symmetries of basic systems
and their simplified versions, different approximations and constitutive turbulent models are compared. A new method to calculate
discrete groups analytically, which does not need a preliminary search for continuous groups, is developed. As an example
of the practical use of the developed algorithm, a complete classification of cellular and roll structures of Bénard convection
is presented. A complete classification of 3D periodic motions in compressible viscous stratified and rotating fluids, including
regular (wave) and singular elements, is performed by perturbation methods. In all cases, in a viscous fluid, besides waves
there are two different periodic boundary layers. In a homogeneous fluid the split boundary layers are merged, thus forming
a joint doubly-degenerate structure. Stratification and rotation reduce the degeneration of the 3D periodic boundary layers.
Calculations of a 3D periodic wave beam emitted by an oscillating part of a sloping plane are visualized by a computer-graphics
method. The existence of thin extended components on the edges of the 3D wave cone is demonstrated. 相似文献
6.
Natallia V. Dubashynskaya Anton N. Bokatyi Anatoliy V. Dobrodumov Igor V. Kudryavtsev Andrey S. Trulioff Artem A. Rubinstein Arthur D. Aquino Yaroslav A. Dubrovskii Elena S. Knyazeva Elena V. Demyanova Yuliya A. Nashchekina Yury A. Skorik 《International journal of molecular sciences》2023,24(1)
The growth of microbial multidrug resistance is a problem in modern clinical medicine. Chemical modification of active pharmaceutical ingredients is an attractive strategy to improve their biopharmaceutical properties by increasing bioavailability and reducing drug toxicity. Conjugation of antimicrobial drugs with natural polysaccharides provides high efficiency of these systems due to targeted delivery, controlled drug release and reduced toxicity. This paper reports a two-step synthesis of colistin conjugates (CT) with succinyl chitosan (SucCS); first, we modified chitosan with succinyl anhydride to introduce a carboxyl function into the polymer molecule, which was then used for chemical grafting with amino groups of the peptide antibiotic CT using carbodiimide chemistry. The resulting polymeric delivery systems had a degree of substitution (DS) by CT of 3–8%, with conjugation efficiencies ranging from 54 to 100% and CT contents ranging from 130–318 μg/mg. The size of the obtained particles was 100–200 nm, and the ζ-potential varied from −22 to −28 mV. In vitro release studies at pH 7.4 demonstrated ultra-slow hydrolysis of amide bonds, with a CT release of 0.1–0.5% after 12 h; at pH 5.2, the hydrolysis rate slightly increased; however, it remained extremely low (1.5% of CT was released after 12 h). The antimicrobial activity of the conjugates depended on the DS. At DS 8%, the minimum inhibitory concentration (MIC) of the conjugate was equal to the MIC of native CT (1 µg/mL); at DS of 3 and 5%, the MIC increased 8-fold. In addition, the developed systems reduced CT nephrotoxicity by 20–60%; they also demonstrated the ability to reduce bacterial lipopolysaccharide-induced inflammation in vitro. Thus, these promising CT-SucCS conjugates are prospective for developing safe and effective nanoantibiotics. 相似文献
7.
Mohammad Mangir Murshed Malik Šehović Michael Fischer Anatoliy Senyshyn Hartmut Schneider Thorsten M. Gesing 《Journal of the American Ceramic Society》2017,100(11):5259-5273
The evolution of metric parameters of 2:1 and 3:2 mullites have been measured between 4 K and 1320 K using neutron and X‐ray powder diffraction. Negative thermal expansion was observed at low temperature for the a‐cell parameter and consequently for the cell‐volume, which is more pronounced for 2:1 mullite than those for 3:2 mullite. Each parameter is simulated using Grüneisen first‐order approximation for the zero pressure equation of state at 0 K, where the vibrational energy was calculated using microscopic approach. While the b‐ and c‐cell parameters require only one Debye term, a second Debye spectrum with negative Grüneisen parameter was required to fit the a‐cell parameter as well as the cell volume. At 4 K, 300 K and 1320 K the model, respectively, calculates the volume thermal expansion coefficients of 0.09x10?6 K?1, 9x10?6 K?1, and 17.3x10?6 K?1 for 2:1 mullite, and 0.09x10?6 K?1, 8.7x10?6 K?1, and 17.3x10?6 K?1 for 3:2 mullite. Temperature‐dependent Raman spectra and phonon density of states hint for the possible microscopic sources of the cell contraction at low temperature. A simple polynomial approach is presented to calculate the elastic stiffness coefficients of the 3:2 mullite, which are not available from experiments. 相似文献
8.
Monitoring of ethylene by a pulsed quantum cascade laser 总被引:2,自引:0,他引:2
We report on the development and performance of a gas sensor based on a quantum cascade laser operating at a wavelength of approximately 10 microns to measure ethylene (C2H4) concentrations by use of a rotational component of the fundamental nu 7 band. The laser is thermoelectrically cooled and operates in a pulsed mode. The influence of pulse-to-pulse fluctuations is minimized by use of a reference beam and a single detector with time discriminating electronics. Gas absorption is recorded in a 100-m optical path-length astigmatic Herriott cell. With a 10-kHz pulse repetition rate and an 80-s total acquisition time, a noise equivalent sensitivity of 30 parts per billion has been demonstrated. The sensor has been applied to monitor C2H4 in vehicle exhaust as well as in air collected in a high-traffic urban tunnel. 相似文献
9.
Polina Vakuliuk Anatoliy Burban Victorya Konovalova Mihailo Bryk Marina Vortman Nina Klymenko Valeriy Shevchenko 《Desalination》2009,235(1-3):160-169
Microbiological contamination of polymeric membranes in the process of their exploitation is an essential problem of membrane technology. It results in the increase of manufacturing costs, destruction of membranes, operating life reduction and secondary contamination of water by the metabolism products of microorganisms. For the purpose of reduction of membrane biofouling and biodegradation investigation of adsorption of the guanidine containing oligomers on the surface of PET track membranes was conducted and their influence on the selectivity and antibacterial properties of the membranes was investigated. It was established that modified membranes have substantially higher resistance to biofouling. 相似文献
10.
Oleg I. Belous Anatoliy I. Fisun Ivan P. Olchovskiy Svetlana P. Sirenko 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(9):1451-1462
The construction and operating characteristics of the highly stabilized millimeter wave IMPATT oscillator are described. The frequency stability is 8.1 × 10-7 at 115 GHz. The output power is no less than 15 mW. The sphere-corner-echelette open resonator have been used for oscillator stabilization. This approach is also adaptable to the Gunn oscillator. 相似文献