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41.
42.
1H n.m.r. and i.r. spectroscopy of aromatic and polar fractions of two tars from the rapid pyrolysis of coal in a fluidized bed at 550 °C show that the nature of the products depends on the reactivity of the pyrolysis gas. In the presence of flue gas, there is more thermolysis leading to shorter and fewer alkyl side chains and generation of lower molecular mass material. Pyrolysis by means of char gasification gas results in much less thermolysis of the tar but leads to secondary reactions which can be interpreted by a radical mechanism involving the reactive constituents of the char gas. 相似文献
43.
Mostafa Zaman Chowdhury Yeong Min Jang Zygmunt J. Haas 《Wireless Personal Communications》2011,60(1):83-104
The femto-access-point, a low-cost and small-size cellular base-station, is envisioned to be widely deployed in subscribers homes, as to provide
high data-rate communications with improved quality of service. As femtocellular networks will co-exist with macrocellular networks, mitigation of the interference between these two network types is a key challenge for successful integration of
these two technologies. In particular, there are several interference mechanisms between the femtocellular and the macrocellular
networks, and the effects of the resulting interference depend on the density of femtocells and the overlaid macrocells in a particular coverage area. While improper interference management can cause a significant reduction in the system capacity
and can increase the outage probability, effective and efficient frequency allocation among femtocells and macrocells can
result in a successful co-existence of these two technologies. Furthermore, highly dense femtocellular deployments—the ultimate
goal of the femtocellular technology—will require significant degree of self-organization in lieu of manual configuration.
In this paper, we present various femtocellular network deployment scenarios, and we propose a number of frequency-allocation
schemes to mitigate the interference and to increase the spectral efficiency of the integrated network. These schemes include:
shared frequency band, dedicated frequency band, sub-frequency band, static frequency-reuse, and dynamic frequency-reuse. We derive an analytical model, which allows us to analyze in details the users outage probability, and we compare the performance
of the proposed schemes using numerical analysis. 相似文献
44.
Zygmunt Kolenda Janusz Donizak Jose C. Escobedo Bocardo 《Metallurgical and Materials Transactions B》1999,30(3):505-513
Classical boundary and initial-boundary value problems in heat and mass transfer are generally formulated in a mathematically
unique way. Boundary and initial conditions together with physical properties of the thermodynamic system are treated as exactly
known. The influence of different kinds of mathematical model simplifications on the accuracy of solution and reliability
of the model are not usually analyzed. The problems become more complicated when inverse ill-posed initial-boundary problems
are considered. The widely used procedure of model validation is based on direct comparison of analytical or numerical solution,
unique in a mathematical sense, with measurement results. The main feature of the method presented in this article is that
all experimental results are included into the mathematical model. Thus, because of the inevitable errors of measurements,
the system of model equations becomes internally contradicted as the number of unknown variables is less than the number of
equations. In consequence, basic laws of energy and mass conservation are not satisfied. To adjust the experimental data to
the mathematical model, an orthogonal least-squares method is proposed. Special attention has been paid to the coupling of
experimental data with the nucleation and grain growth models formulated by Rappaz and co-workers. Theoretical considerations
are illustrated with experimental data for an Al-Si alloy. 相似文献
45.
Tomasz Dbski Ewa Kijeska-Gawroska Aleksandra Zoociska Katarzyna Siennicka Anna Sysz Wiktor Paskal Pawe K. Wodarski Wojciech
wiszkowski Zygmunt Pojda 《International journal of molecular sciences》2021,22(11)
The aim was to examine the efficiency of a scaffold made of poly (L-lactic acid)-co-poly(ϵ-caprolactone), collagen (COL), polyaniline (PANI), and enriched with adipose-derived stem cells (ASCs) as a nerve conduit in a rat model. P(LLA-CL)-COL-PANI scaffold was optimized and electrospun into a tubular-shaped structure. Adipose tissue from 10 Lewis rats was harvested for ASCs culture. A total of 28 inbred male Lewis rats underwent sciatic nerve transection and excision of a 10 mm nerve trunk fragment. In Group A, the nerve gap remained untouched; in Group B, an excised trunk was used as an autograft; in Group C, nerve stumps were secured with P(LLA-CL)-COL-PANI conduit; in Group D, P(LLA-CL)-COL-PANI conduit was enriched with ASCs. After 6 months of observation, rats were sacrificed. Gastrocnemius muscles and sciatic nerves were harvested for weight, histology analysis, and nerve fiber count analyses. Group A showed advanced atrophy of the muscle, and each intervention (B, C, D) prevented muscle mass decrease (p < 0.0001); however, ASCs addition decreased efficiency vs. autograft (p < 0.05). Nerve fiber count revealed a superior effect in the nerve fiber density observed in the groups with the use of conduit (D vs. B p < 0.0001, C vs. B p < 0.001). P(LLA-CL)-COL-PANI conduits with ASCs showed promising results in managing nerve gap by decreasing muscle atrophy. 相似文献
46.
47.
Dariusz Bochenek Zygmunt Surowiak Józef Krok-Kowalski Jana Poltierova-Vejpravova 《Journal of Electroceramics》2010,25(2-4):122-129
An influence of compacting conditions on applied properties of the multiferroic PbFe1/2Nb1/2O3 (PFN) ceramics synthesized by the columbite method and powder calcination technique is presented in this work. The obtained specimens were subjected to X-ray and chemical composition homogeneity analyses, magnetic tests, electric direct current conductivity and electromechanical tests. Differences in the degree of diffuseness, densities and a grain size were observed depending on the sintering method. The dielectric and magnetic parameters as a function of temperature were measured. The tests confirmed that PFN powder compacting by a hot uniaxial pressing method had an advantageous influence on the crystalline structure ordering and the ceramics microstructure, what improves the applied properties of the material. 相似文献
48.
The variability of the proximate composition and fatty acid profiles in samples of sprat (Sprattus sprattus balticus) from the southern Baltic Sea were studied in relation to the catch season and location, individual fish size, and sex. Fatty acid profiles depended on such features as fish size and lipid content, which depend on the season of the year in which the fish were caught. No differences in fatty acid profiles were noted between the sexes in the individuals examined. Studies on fish lipids are necessary as fish lipids are important in the prevention of cardiac disease. One of the chief advantages of fish lipids that is relevant to the prevention of cardiac disease is their n−3 to n−6 fatty acid ratio. The most advantageous ratio of these fatty acids was noted in sprat that were the smallest in length. 相似文献
49.
Jiantao Pu Yagnanarayanan Kalyanaraman Subramaniam Jayanti Karthik Ramani Zygmunt Pizlo 《Computer Graphics and Applications, IEEE》2007,27(4):38-47
Due to increasing product design complexities and the ever-expanding variety of product parts, the amount of information that designers must catalog has exploded. Accordingly, capable CAD tools to help designers create engineering artifacts are now pervasive. The volume of such engineering artifacts generated has increased exponentially and enterprises spend huge resources to organize and archive them into repositories. In these large design repositories, traditional text-based searches prove unwieldy and impractical, and are thus insufficient for individuals seeking 3D content. The paper explains that while traditional text-based searches are impractical for users seeking 3D content in large repositories, existing 3D search systems present search results in a 1D list, which is hard to search. A new interaction paradigm lets users navigate results in 2D and 3D spaces and easily find 3D models that are similar overall or in a single orientation. 相似文献
50.
The activity of several NiMoly catalysts in the processes of dehydrogenation of tetralin or decalin and hydrogenation of coal-extract solution has been determined. In both processes studied, the activities of the catalysts investigated have been found to follow rectilinear relations with quantity. It has also been shown that the activity of a NiMoly catalyst can be predicted in hydrogenation of coal-extract solution, from its activity in dehydrogenation of tetralin or decalin; the latter reaction is relatively simple to conduct in laboratory conditions. However, caution must be exercised when very narrow pores, making possible Knudsen diffusion of hydrogen at high pressure, exist in the catalyst. 相似文献