197 research outputs found
Time evolution of spin state of radical ion pair in microwave field: An analytical solution
The paper reports an exact solution for the problem of spin evolution of
radical ion pair in static magnetic and resonant microwave field taking into
account Zeeman and hyperfine interactions and spin relaxation. The values of
parameters that provide one of the four possible types of solution are
analysed. It is demonstrated that in the absence of spin relaxation, besides
the zero field invariant an invariant at large amplitudes of the resonant
microwave field can be found. The two invariants open the possibility for
simple calculation of microwave pulses to control quantum state of the radical
pair. The effect of relaxation on the invariants is analysed and it is shown
that changes in the high field invariant are induced by phase relaxation.Comment: 18 pages, 7 figure
Methodological approaches to evaluation of efficiency of new biotechnologies for remediation of soils contaminated with oil and oilfield liquids
© 2018 Neftyanoe Khozyaistvo. All rights reserved. Currently available is a wide range of biotechnologies for remediation of oil-polluted areas. These are based on application of hydrocarbon oxidizing microorganisms, humic compounds, and sorbents, which have various efficiency depending on the nature of pollution, climatic conditions, grain size distribution, and soil type. The purpose of the present research effort is to summarize the lessons learned in evaluation of the performance of new biotechnologies for remediation of soils contaminated with oil or oilfield liquid. Integrated performance assessment of biotechnologies for soil remediation should include the following diagnostic blocks: determination of oil product content, agrochemical and microbiological parameters, toxicological characteristics, mutagenicity of soil samples and phytoproductivity. Infrared spectrometry is recommended for determination of petroleum product content. This method provides for extraction of petroleum products from soil using tetrachloride carbon, chromatographic separation from associated organic compounds of other classes and quantitative analysis based on intensity of infrared absorption. Determination of agroecological parameters in soil samples involves рН of aqueous and salt extracts, chlorides, sulfates, dissolved solids of aqueous extract, humic matter, alkali hydrolyzable nitrogen, labile phosphorous compounds and exchange potassium. Microbiological monitoring includes determination of the amount of hydrocarbon oxidizing, heterotrophic microorganisms, micromycetes, total microbial biomass and basal respiration. Analysis of soil mutagenic activity is a part of soil assessment process. Of the several technologies available for identification of mutagenes, the most common are tests on microorganisms, fruit fly, in vitro tests using mammal cell cultures, mammalian in vivo micronucleus tests
Simulation of Coherent Diffraction Radiation Generation by Pico-Second Electron Bunches in an Open Resonator
In this report we present new approach for calculation of processes of diffraction radiation generation, storage and decay in an open resonator based on generalized surface current method. The radiation characteristics calculated using the developed approach were compared with those calculated using Gaussian-Laguerre modes method. The comparison shows reasonable coincidence of the results that allows to use developed method for investigation of more complicated resonators
Assessment of oil treatment facilities impact on radiation environment in adjacent areas
Upstream and downstream activities result in large environmental emissions of natural radionuclides. Specific activity of radionuclides in soil samples from Tatneft assets was analyzed to evaluate oil treatment facilities impact on radiation pollution of the environment. Reliable identification of radio-geochemical anomalies was achieved through landscape-geochemical zoning and detailed analysis using R statistical software
Cluster analysis and classification of process data by use of principal curves
Thesis (M.Ing.) -- University of Stellenbosch, 1999.ENGLISH SUMMARY: In this thesis a new method of clustering as wen as a new method of classification is
proposed. Cluster analysis is a statistical method used to search for natural groups in
an unstructured multivariate data set. Clusters are obtained in such. a way that the
observations belonging to the same group are more alike than observations across
groups. For instance, long data records are found in mineral processing plants, where
the data can be reduced to clusters according to different ore types. Most of the
existing clustering methods do not give reliable results when applied to engineering
data, since these methods were mainly developed in the domains of psychology and
biology.
Classification analysis can be regarded as the natural continuation of cluster analysis.
In order to classify objects, two types of observations are needed. The first are those
observations whose group memberships are known a priori, which can be acquired
through cluster analysis. The second kind of observations are those whose group
memberships are unidentified. By means of classification these observations are
allocated to one of the existing groups.
Both of the proposed techniques are based on the use of a smooth one-dimensional
curve, passing through the middle of the data set. To formalise such an idea,
principal curves were developed by Hastie and Stuetzle (1989). A principal curve
summarises the data in a non-linear fashion. For clustering, the principal curve of the
entire unstructured data set is extracted. This one-dimensional representation of the
data set is then used to search for different clusters. For classification, a principal
curve is fitted to every known group in the data set. The observations to be assigned
to one of the known groups are allocated to the group closest to the new point.
Clustering with principal curves grouped engineering data better than most of the
well-known clustering algorithms. Some shortcomings of this method were also
established. Classification with principal curves gave similar, optimal results as compared to some existing classification methods. This classification method can be
applied to data of any distribution, unlike statistical classification techniques.AFRIKAANSE OPSOMMING: In hierdie tesis word 'n nuwe metode elk vir trosanalise en klassifikasie analise
voorgestel. Trosanalise is 'n statistiese tegniek waarrnee natuurlike groepe in 'n
ongestruktureerde meerveranderlike datastel gevind word. Groepe word op so 'n
wyse verkry dat die waamemings in dieselfde groep meer eenders is as waarnemings
tussen groepe. Byvoorbeeld, in mineraalaanlegte is lang datarekords algemeen, wat
deur middel van trosanalise gereduseer kan word na verskillende groepe,
ooreenkomstig verskillende ertstipes. Die meerderheid bestaande groeperingsmetodes
lewer nie betroubare resultate in hul toepassing op ingenieursdata nie, aangesien
hierdie tegnieke meestal hul oorsprong in die sielkundige en biologiese velde het.
Klassifikasie analise kan gesien word as die natuurlike opvolging van trosanalise.
Om objekte te klassifiseer, word gebruik gemaak van twee soorte waarnemings. Die
eerste tipe is daardie waamemings met a priori bekende groepsidentiteite, wat deur
trosanalise gevind kan word. Die tweede soort is die waarnemings met onbekende
groepsidentiteite. Elkeen van hierdie waarnemings kan deur middel van klassifikasie
toegewys word aan een van die bestaande groepe.
Beide hierdie voorgestelde tegnieke is gebaseer op die gebruik van 'n gladde, eendimensionele
kromme wat deur die middel van die datastel beweeg. Om hierdie idee
te formaliseer, is hoojkrommes ontwikkel deur Hastie en Stuetzle (1989). 'n
Hoofkromme gee 'n nie-lineere opsomming van die data. Vir groeperingsdoeleindes
word 'n hoofkromme uit die algehele ongestruktureerde datastel onttrek. Met
klassifikasie word'n hootkurwe aan elke bekende groep in die datastel gepas. Die
waameming wat aan een van die bestaande groepe toegewys moet word, word in die
groep naaste aan die betrokke punt geplaas.
Groepering met behulp van hoofkrommes, het met ingenieursdata beter resultate
gelewer as meeste van die bestaande tegnieke. Deur middel van praktiese voorbeelde
is sekere tekortkominge van hierdie groeperingsmetode vasgestel. Klassifikasie met behulp van hoofkrornmes lewer soortgelyke, optimale resultate as die van bekende
vergelykende tegnieke. Die voorgestelde klassifikasie tegniek kan toegepas word op
datastelle van enige verde ling, in teenstelling met die statistiese klassifikasietegnieke.Maste
One-step synthesis of 2,5-bis(chloromethyl)-1,4-dioxane from epichlorohydrin using ZIF-8, taking advantage of structural defects
We demonstrate herein the ZIF-8-only-mediated catalysis of the cyclodimerization of epichlorohydrin to 2,5-bis(chloromethyl)-1,4-dioxane in the absence of co-catalyst and solvent. The easy handling and economic aspects of ZIF-8, in addition to the one-step reaction to produce the cyclodimer, make this catalyst attractive even for industry. It has been clearly illustrated that the nature of the method used to synthesize ZIF-8 affected the yields of the cyclodimers. Specifically, the method employed to produce ZIF-8 directly influences the amount of crystal structural defects, which in turn impacts their performance as catalysts. To emphasize the role of defects, other physical properties, such as surface area and particle size, were controlled during the synthesis of the ZIF-8 catalysts. Remarkably, the amount of structural defects was quantified by temperature program desorption analysis
Status of the Novosibirsk terahertz FEL
The first stage of Novosibirsk high-power free-electron laser (FEL) was commissioned in 2003. It is based on a
normal conducting CW energy recovery linac. Now the FEL provides electromagnetic radiation in the wavelength
range of 120…180 micrometers. An average power is 400 W. The minimum measured line width is 0.3%, which is
close to the Fourier-transform limit. A user-beamline assembly is in progress, parts of the full-scale machine are
manufactured. The latter will operate in the near IR region and provide higher average powerВ 2003 году в Новосибирске заработала первая очередь мощного лазера на свободных электронах (ЛСЭ).
Машина построена на базе линака-рекуператора непрерывного действия. В настоящее время ЛСЭ работает в
диапазоне длин волн 120…180 мкм, его средняя мощность достигает 400 Вт. Минимальная измеренная ши-
рина полосы излучения составляет 0.3%, что близко к теоретическому минимуму. В настоящее время
монтируются каналы разводки излучения для пользователей, части полномасштабной машины запущены в
производство. Полномасштабная машина будет работать в ближнем ИК-диапазоне и обладать большей
мощностью.В 2003 році в Новосибірську заробила перша черга потужного лазера на вільних електронах (ЛВЕ).
Машина побудована на базі лінака-рекуператора безперервної дії. Зараз ЛВЕ працює в діапазоні довжин
хвиль 120...180 мкм, його середня потужність досягає 400 Вт. Мінімальна виміряна ширина смуги
випромінювання становить 0.3%, що близько до теоретичного мінімуму. Зараз монтуються канали
розведення випромінювання для користувачів, частини повномасштабної машини запущені у виробництво.
Повномасштабна машина буде працювати в ближньому ІЧ-діапазоні і мати більшу потужність
First experimental results obtained using the highpower free electron laser at the siberian center for photochemical research
The first lasing near the wavelength of 140 µm was achieved in April 2003 using a high-power free electron laser (FEL) constructed at the Siberian Center for Photochemical Research. In this paper we briefly describe the design of the FEL driven by an accelerator–recuperator. Characteristics of the electron beam and terahertz laser radiation, obtained in the first experiments, are also presented in the paper.У Сибірському центрі фотохімічних досліджень навесні 2003 року отримана генерація випромінювання з довжиною хвилі 140 мкм на потужному лазері на вільних електронах (ЛВЕ). У роботі коротко описана конструкція ЛВЕ на базі прискорювача рекуператора і представлені результати вимірювання деяких параметрів електронного пучка і терагерцового випромінювання.В Сибирском центре фотохимических исследований весной 2003 года получена генерация излучения с длиной волны 140 мкм на мощном лазере на свободных электронах (ЛСЭ). В работе кратко описана конструкция ЛСЭ на базе ускорителя рекуператора и представлены результаты измерения некоторых параметров электронного пучка и терагерцового излучения
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