4,093 research outputs found
A combinatorial approach to the set-theoretic solutions of the Yang-Baxter equation
A bijective map , where
is a finite set, is called a \emph{set-theoretic solution of the Yang-Baxter
equation} (YBE) if the braid relation
holds in A non-degenerate involutive solution satisfying
, for all , is called \emph{square-free solution}. There
exist close relations between the square-free set-theoretic solutions of YBE,
the semigroups of I-type, the semigroups of skew polynomial type, and the
Bieberbach groups, as it was first shown in a joint paper with Michel Van den
Bergh.
In this paper we continue the study of square-free solutions and the
associated Yang-Baxter algebraic structures -- the semigroup , the
group and the - algebra over a field , generated by
and with quadratic defining relations naturally arising and uniquely
determined by . We study the properties of the associated Yang-Baxter
structures and prove a conjecture of the present author that the three notions:
a square-free solution of (set-theoretic) YBE, a semigroup of I type, and a
semigroup of skew-polynomial type, are equivalent. This implies that the
Yang-Baxter algebra is Poincar\'{e}-Birkhoff-Witt type algebra,
with respect to some appropriate ordering of . We conjecture that every
square-free solution of YBE is retractable, in the sense of Etingof-Schedler.Comment: 34 page
Time dependent correlations in marine stratocumulus cloud base height records
The scaling ranges of time correlations in the cloud base height records of
marine boundary layer stratocumulus are studied applying the Detrended
Fluctuation Analysis statistical method. We have found that time dependent
variations in the evolution of the exponent reflect the diurnal
dynamics of cloud base height fluctuations in the marine boundary layer. In
general, a more stable structure of the boundary layer corresponds to a lower
value of the - indicator, i.e. larger anti-persistence, thus a set of
fluctuations tending to induce a greater stability of the stratocumulus. In
contrast, during periods of higher instability in the marine boundary, less
anti-persistent (more persistent like) behavior of the system drags it out of
equilibrium, corresponding to larger values. From an analysis of the
frequency spectrum, the stratocumulus base height evolution is found to be a
non-stationary process with stationary increments. The occurrence of these
statistics in cloud base height fluctuations suggests the usefulness of similar
studies for the radiation transfer dynamics modeling.Comment: 12 pages, 6 figures; to appear in Int. J. Mod. Phys. C, Vol. 13, No.
2 (2002
Influence of raw material properties on the quality of solid biofuel and energy consumption in briquetting process
ArticleThe present paper is related to a pressing process research of raw materials with
different density in order to investigate impact of biomass density on a formation of monolithic
structure and the briquette’s strength. Another focus of the study is an influence of raw materials
particles’ size on agglomeration process and quality of final product. Different biomass materials
like two varieties of miscanthus, industrial hemp and apple wood were selected for experimental
purposes of this research. Mechanical durability which represents one the main indicator of
briquettes’ mechanical quality (strength) was determined. The research was conducted using
hydraulic piston briquetting press. For assessment of briquetting efficiency during the whole
process energy consumption was measured. One of the most important factors that can affect
briquetting process is the temperature of pressing chamber which was registered as well. The
main goal of the research was practical study of possibilities for increasing production efficiency
and quality of briquettes on hydraulic piston briquetting press with respect to optimization of
particles’ size of raw materials and use of raw materials the most appropriate density
Using of high-speed mills for biomass disintegration
ArticleThe need for mechanical disintegration of biomass is very current topic with regard to
the requirements of an agrarian sector, beside the importance of a material’s moisture content
reduction to be used in further applications. The drawbacks of commonly applied devices are the
limited use of moist biomass and high energy consumption for disintegration. In collaboration
with LAVARIS company, there were tested two high-speed mills LAV 400/1R with single rotor
(used for a first milling) and LAV 300/2R with double rotors (used for a second milling), which
were primarily designed for crushing of concrete, rubber and construction waste. The goal of the
new technical solution was a disintegration of biomass on example of pine sawdust and
miscanthus together with examination of simultaneous drying in order to achieve a desired
fraction (particle size) and moisture content of biomass material. Experimental tests on highspeed mills have shown the following results: in case of pine sawdust about 98% of output particle
size after passing through the first and second milling was smaller than 1.5 mm, and smaller than
1 mm for miscanthus (sieve analysis method was used for determination), i.e. significant
reduction was achieved comparing to initial particle size. Moisture content of the materials after
disintegration (first and second) decreased from 37.08% to 8.55% for pine sawdust and from
24.43% to 7.19% for miscanthus. Based on the results, it can be concluded that the mechanical
disintegration of biomass by high-speed mills has a great potential to become an effective part of
raw materials’ pre-treatment technology, not only in agriculture, but also in production of
different types of biofuels
КОНЦЕПТУАЛЬНІ ПІДХОДИ ДО СИСТЕМАТИЗАЦІЇ МЕТОДІВ ОЦІНКИ ЯКОСТІ МЕДИЧНОЇ ДОПОМОГИ
Methodology of estimating the quality of medical care is offered. On the basis of generalization of world experience and new authorial developments on original quadrupole model of process of estimating the quality of medical care is offered. A model consists of four clusters which contain four criteria for estimating the quality of medical care and corresponding indeces for the analysis of these criteria. Clusters have been presented as an integral estimation of quality of medical care, technological, methodological and estimation of quality of medical care on separate additional criteria. The detailed description of clusters and indeces has been accordingly given. A particular attention has been paid to the mathematical design of processes of estimating the quality of medical care. Indisputable advantages of the worked out quadrupole model are simplicity of its introduction and availability for understanding by medical personnel.Предлагается методология оценки качества медицинской помощи. На основании обобщения мирового опыта и на основе авторских разработок предлагается оригинальная квадрупольная модель процесса оценки качества медицинской помощи. Модель состоит из четырех кластеров, включающих по четыре критерия оценки качества медицинской помощи и соответствующие показатели для анализа этих критериев. Кластеры представлены как интегральная оценка качества медицинской помощи, технологическая, методологическая и оценка качества медицинской помощи по отдельным дополнительным критериям. Представлена детальная характеристика кластеров и показателей. Отдельно освещено математическое моделирование процессов оценки качества медицинской помощи. К бесспорным преимуществам разработанной квадрупольной модели отнесены простота ее внедрения и доступность для понимания медицинским персоналом.Пропонується методологія оцінки якості медичної допомоги. На підставі узагальнення світового досвіду та на основі авторських розробок пропонується оригінальна квадрупольна модель процесу оцінки якості медичної допомоги. Модель складається з чотирьох кластерів, що містять по чотири критерії оцінки якості медичної допомоги та відповідні показники для аналізу цих критеріїв. Кластери представлені як інтегральна оцінка якості медичної допомоги, технологічна, методологічна та оцінка якості медичної допомоги за окремими додатковими критеріями. Представлена детальна характеристика кластерів та показників.Окремим розділом висвітлено математичне моделювання процесів оцінювання якості медичної допомоги. До безперечних переваг розробленої квадрупольної моделі віднесено простоту її впровадження та доступність для розуміння медичним персоналом.
Results of investigation of muon fluxes of superhigh energy cosmic rays with X-ray emulsion chambers
The overall data from the investigation of the cosmic ray muon flux in the range of zenith angles (0-90) deg within the energy range (3.5 to 5.0) TeV is presented. The exposure of large X-ray emulsion chambers underground was 1200 tons. year. The data were processe using the method which was applied in the experiment Pamir and differred from the earlier applied one. The obtained value of a slope power index of the differential energy spectrum of the global muon flux is =3.7 that corresponds to the slope of the pion generation differential spectrum, gamma sub PI = 2.75 + or - .04. The analysis of the muon zenith-angular distribution showed that the contribution of rapid generation muons in the total muon flux agree the best with the value .2% and less with .7% at a 90% reliability level
Mercaptophosphonic acids as efficient linkers in quantum dot sensitized solar cells
Control over the deposition of quantum dots (QDs) on nanostructured semiconductors is very important for the photovoltaic performance of QD sensitized solar cells. The best control is typically achieved using bifunctional molecular linkers, such as mercaptopropionic acid (MPA), to attach the QDs to metal oxides in a specific manner; however some materials, such as ZnO, are not compatible with these molecules due to their pH sensitivity. We have developed new linkers, mercaptophosphonic acids of different length, which allow efficient functionalization of ZnO nanowires and also mesoporous TiO2 without damaging their surface. Detailed XPS and contact angle studies of the mechanism of self-assembly of these acids show that their strong chelation of the oxide surface prevents protonic attack and etching. Using these linkers, we show that colloidal ternary quantum dots, CuInS2, can be conformally and homogeneously deposited on the functionalized metal oxides. Photophysical studies by means of time-resolved photoluminescence spectroscopy confirm efficient electron transfer from the QDs to the metal oxides with the rate and efficiency scaling with respect to the linker length and nature. The efficiency of the QD sensitized solar cells fabricated with such assemblies also strongly depends on the linkers used and follows the trends observed for the charge transfer
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