Вопросы обеспечения единства измерений при межведомственных испыта-ниях спектрометров для трибодиагностики ГТД

The article is devoted to the organization of ensuring problem how to obtain the uniformity of measurements at in-teragency testing of new generation of tribodiagnostics of aircraft GTE on the example of the x-ray spectrum analyzers. The article provides a synthesis of the obtained in testing results of measuring the concentration of products of wear pro-cess taking place in working oils, as well as recommendations and conclusions.Статья посвящена вопросам организации обеспечения единства измерений при проведении межведомственных испытаний нового поколения средств трибодиагностики авиационных ГТД на примере рентгеноспектральных анализаторов. Приводится обобщение полученных при испытаниях результатов измерений концентрации продуктов изнашивания в работающих маслах, а также даются рекомендации и выводы

Is it really possible to grow isotropic on-lattice diffusion-limited aggregates?

In a recent paper (Bogoyavlenskiy V A 2002 \JPA \textbf{35} 2533), an algorithm aiming to generate isotropic clusters of the on-lattice diffusion-limited aggregation (DLA) model was proposed. The procedure consists of aggregation probabilities proportional to the squared number of occupied sites ($k^2$). In the present work, we analyzed this algorithm using the noise reduced version of the DLA model and large scale simulations. In the noiseless limit, instead of isotropic patterns, a $45^\circ$ ($30^\circ$) rotation in the anisotropy directions of the clusters grown on square (triangular) lattices was observed. A generalized algorithm, in which the aggregation probability is proportional to $k^\nu$, was proposed. The exponent $\nu$ has a nonuniversal critical value $\nu_c$, for which the patterns generated in the noiseless limit exhibit the original (axial) anisotropy for $\nu<\nu_c$ and the rotated one (diagonal) for $\nu>\nu_c$. The values $\nu_c = 1.395\pm0.005$ and $\nu_c = 0.82\pm 0.01$ were found for square and triangular lattices, respectively. Moreover, large scale simulations show that there are a nontrivial relation between noise reduction and anisotropy direction. The case $\nu=2$ (\bogo's rule) is an example where the patterns exhibit the axial anisotropy for small and the diagonal one for large noise reduction.Comment: 12 pages, 8 figure

АНАЛИЗ ПРОЦЕДУР ОБЕCПЕЧЕНИЯ ДОCТОВЕРНОCТИ CРЕДCТВ И МЕТОДОВ ИЗМЕРЕНИЯ ВИБРАЦИИ В ПРОЦЕCCАХ ПОДДЕРЖАНИЯ ЛЕТНОЙ ГОДНОCТИ ВОЗДУШНЫХ CУДОВ

On the basis of system approach the structure of the aviation activity areas on air transport related to monitoring and measurements of vibration parameters is presented.The technology analysis of laboratory tests of the onboard equipment control of vibration parameters is carried out. The issues related to ensuring the unity of measurements of vibration parameters are researched and summarized.While dealing with the works on metrological certification described in the article, the risks arising from aviation activity on air transport are taken into account. The certification methods of measuring channels of vibration parametersused on stands for testing GTE at the repairing of aircraft engines are developed. The methods are implemented when conducting initial and periodic certifications of test benches for twelve types of aircraft GTE in repair organizations. The reliability of the results of the conducted research due to the fact that they were carried out with the use of certified measurement equipment, included in the State register of measuring instruments. The research is conducted for a sufficiently high statistical confidence level with the boundaries 0.95. The studies have shown that running on air transport measurements of vibration parameters are metrologically secured, the unity of measurements and their traceability from the national primary reference to special measuring instruments, test equipment, and onboard controls of the aircraft is maintained.На основе системного подхода представлена структура направлений авиационной деятельности на воздушном транспорте, связанных с контролем и измерениями параметров вибрации, наблюдаемой на авиационной технике.Проведен анализ технологий лабораторных проверок бортовой аппаратуры контроля параметров вибрации, исследованы и обобщены вопросы, связанные с обеспечением единства измерений параметров вибрации воз-душных судов с газотурбинными двигателями.В процессе выполнения описанных в статье работ по аттестации учтены метрологические риски, возника-ющие при производстве авиационной деятельности на воздушном транспорте. Разработаны методы проведенияаттестации измерительных каналов параметров вибрации, применяемых на стендах испытательных станций приремонте авиационных двигателей.Методы внедрены при проведении первичных и периодических аттестаций испытательных стендов длядвенадцати типов авиационных газотурбинных двигателей в организациях по ремонту. Достоверность результатовпроведенных исследований обусловлена тем, что они проводились с применением аттестованного измерительногооборудования, внесенного в Государственный реестр средств измерений. Исследования проведены для достаточновысокого статистического уровня достоверности с границами 0,95.Проведенные исследования показали, что выполняемые на воздушном транспорте измерения параметроввибрации метрологически обеспечены: поддерживается единство измерений и их прослеживаемость от государ-ственного первичного эталона до специальных средств измерений, испытательного оборудования и бортовыхсредств контроля воздушных судов.В статье содержатся нормы по контролю параметров вибрации, виды проверок, место их проведения, при-меняемое оборудование и инструментарий

Метрологическое обеспечение эксплуатационных испытаний наземной ав-томатизированной системы контроля: методология и анализ результатов

The article is devoted to the methodology of metrological assurance during of operational test of the new-gen ground-based automated control of system. On the example of ATE-200, designed to measure the parameters (to diagnose) onboard means of control and other aircraft equipment. The basic test results have been summarized and presented.В статье излагаются вопросы методологии метрологического обеспечения при проведении эксплуатационных испытаний наземной автоматизированной системы контроля нового поколения. На примере НАСКД-200, предназначенной для контроля параметров (диагностирования) бортовых средств контроля и иного авиационного оборудования, проведено обобщение и представлен анализ основных результатов, полученных при испытаниях

Experimental study of negative photoconductivity in n-PbTe(Ga) epitaxial films

We report on low-temperature photoconductivity (PC) in n-PbTe(Ga) epitaxial films prepared by the hot-wall technique on -BaF_2 substrates. Variation of the substrate temperature allowed us to change the resistivity of the films from 10^8 down to 10_{-2} Ohm x cm at 4.2 K. The resistivity reduction is associated with a slight excess of Ga concentration, disturbing the Fermi level pinning within the energy gap of n-PbTe(Ga). PC has been measured under continuous and pulse illumination in the temperature range 4.2-300 K. For films of low resistivity, the photoresponse is composed of negative and positive parts. Recombination processes for both effects are characterized by nonexponential kinetics depending on the illumination pulse duration and intensity. Analysis of the PC transient proves that the negative photoconductivity cannot be explained in terms of nonequilibrium charge carriers spatial separation of due to band modulation. Experimental results are interpreted assuming the mixed valence of Ga in lead telluride and the formation of centers with a negative correlation energy. Specifics of the PC process is determined by the energy levels attributed to donor Ga III, acceptor Ga I, and neutral Ga II states with respect to the crystal surrounding. The energy level corresponding to the metastable state Ga II is supposed to occur above the conduction band bottom, providing fast recombination rates for the negative PC. The superposition of negative and positive PC is considered to be dependent on the ratio of the densities of states corresponding to the donor and acceptor impurity centers.Comment: 7 pages, 4 figure

Diffusion-limited aggregation: A relationship between surface thermodynamics and crystal morphology

We have combined the original diffusion-limited aggregation model introduced by Witten and Sander with the surface thermodynamics of the growing solid aggregate. The theory is based on the consideration of the surface chemical potential as a thermodynamic function of the temperature and nearest-neighbor configuration. The Monte Carlo simulations on a two-dimensional square lattice produce the broad range of shapes such as fractal dendritic structures, densely branching patterns, and compact aggregates. The morphology diagram illustrating the relationship between the model parameters and cluster geometry is presented and discussed.Comment: 5 pages, 6 figure

Newcastle Disease Virus in Madagascar: Identification of an Original Genotype Possibly Deriving from a Died Out Ancestor of Genotype IV

In Madagascar, Newcastle disease (ND) has become enzootic after the first documented epizootics in 1946, with recurrent annual outbreaks causing mortality up to 40%. Four ND viruses recently isolated in Madagascar were genotypically and pathotypically characterised. By phylogenetic inference based on the F and HN genes, and also full-genome sequence analyses, the NDV Malagasy isolates form a cluster distant enough to constitute a new genotype hereby proposed as genotype XI. This new genotype is presumably deriving from an ancestor close to genotype IV introduced in the island probably more than 50 years ago. Our data show also that all the previously described neutralising epitopes are conserved between Malagasy and vaccine strains. However, the potential implication in vaccination failures of specific amino acid substitutions predominantly found on surface-exposed epitopes of F and HN proteins is discussed