Atomistic Simulations of the Efficiencies of Ge and Pt Ion Implantation into Graphene

Recent success in the direct implantation of 74Ge+ ion, the heaviest atomic impurity to date, into monolayer graphene presents a general question of the efficiency of low-energy ion implantation technique for heavy atoms. A comparative computational study, using classical molecular dynamics, of low-energy Ge and Pt ions implantation into single- and double-layer graphene is presented. It confirms that the highest probability for the perfect substitutional doping of single-layer graphene, i.e., direct implanting of ion into monovacancy, can be achieved 80 eV and it reaches the value of 64% for Ge ions directed at 45° angle to graphene plane and 21% for Pt ion beam perpendicular to graphene. Implantation efficiency is strongly dependent on the angle of ion beam. The sputtering yield of carbon atoms is found to be lower for double layer of graphene, which has better protective properties against low-energy ion irradiation damage than a single graphene layer. In double-layer graphene, incident ions traveling in the direction perpendicular to graphene can be trapped between the layers with the highest efficiency above or equal to 80% in the energy range of 40–90 eV for Ge ions and above 90% in the energy range of 40–70 eV for Pt ions. The energy range corresponding to the efficient trapping of ions in double-layer graphene is shifted toward higher energies upon tilting of the angle of incident ion beam

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ПОДАВЛЕНИЯ АКТИВНЫХ ПОМЕХ В РЛС ПЕРЕХВАТА ВОЗДУШНЫХ ЦЕЛЕЙ В РЕЖИМЕ ОБЗОРА

The modified algorithm of the adaptive compensating of the active noise jamming, based on usage of the recurrence estimation of inverse covariance matrix of jamming in the course of an self-tuning is considered. The matrix estimation is formed by a method of a serial regression (SRM), a consequence application of a lemma about inversing of a matrix to differential – to the difference equation for a rounded estimation of direct covariance matrix of jamming (CMJ). The single estimation of straight line CMJ is formed as result dyad products of the instant vectors of noises in handling channels. In partial channels the adaptive transversal filters with the self-tuning on value of a signal of an aggregate error are implemented.In article skeleton diagrams of devices of the compensating implemented by various methods are resulted. Mathematical modeling of operation of the algorithms, implemented by a method of the least squares (criterion of a minimum RMS error) and a method of a serial regression is performed.Results of mathematical modeling of operation of the device of compensating of active noises jamming in the conditions of the active radio-electronic counteraction at multipath propagation of signals both non-identical amplitude and phase characteristics of channels of handling are resulted. Optimal values of technical parameters of devices of compensating of the active noises jamming providing obtaining of demanded values of coefficient of suppression are given. The comparative analysis of indexes of efficiency of classical and offered algorithms of compensating is made. Advantage of algorithm of compensating of the active noises jamming, using the recurrence estimation of a inverse covariance matrix of jamming is shown.The algorithm of functioning on the basis of SRM allows to lower essentially requirements to specialized VLSI (FPGA) at implementation is hardware – program complexes for preprocessing of the radar, radio communication and radio – navigation information in the conditions of influence of the active noises jamming in the presence of effects of multipath propagation of signals, in the presence of delay of signals on an antenna system aperture, and also at unremovable technological dispersion amplitude and phase characteristics of the microwave of channels of handling.Рассматривается модифицированный алгоритм адаптивной компенсации активных шумовых помех, основанный на использовании рекуррентной оценки обратной ковариационной матрицы помех в процессе самонастройки. Оценка матрицы формируется методом последовательной регрессии (МПР), являющегося следствием применения леммы об обращении матрицы к дифференциально-разностному уравнению для сглаженной оценки прямой ковариационной матрицы помех (КМП). Разовая оценка прямой КМП формируется как результат диадного произведения мгновенных векторов помех в каналах обработки. В парциальных каналах реализуются адаптивные трансверсальные фильтры с самонастройкой по величине сигнала суммарной ошибки. В статье приведены структурные схемы устройств компенсации, реализованных различными способами.Выполнено математическое моделирование работы алгоритмов, реализованного методом наименьших квадратов (критерий минимума среднеквадратической ошибки) и методом последовательной регрессии.Приводятся результаты математического моделирования работы устройства компенсации помех в условиях активного радиоэлектронного противодействия при многолучевом распространении сигналов и неидентичных амплитудных и фазовых характеристиках каналов обработки. Даны оптимальные значения технических параметров устройств компенсации помех, обеспечивающих получение требуемых величин коэффициента подавления. Выполнен сравнительный анализ показателей эффективности классического и предлагаемого алгоритмов компенсации. Показано преимущество алгоритма компенсации активных помех, использующего рекуррентную оценку обратной ковариационной матрицы помех.Алгоритм функционирования на основе МПР позволяет существенно снизить требования к специализированным СБИС (ПЛИС) при реализации аппаратно-программных комплексов для первичной обработки радиолокационной, радиосвязной и радионавигационной информации в условиях воздействия активных шумовых помех при наличии эффектов многолучевого распространения сигналов, при наличии запаздывания сигналов по раскрыву антенной системы, а также при неустранимом технологическом разбросе амплитудно-фазовых характеристик СВЧ-тракта каналов обработки

Termination Reaction in the Anionic Polymerization of Methacrylonitrile

The anionic polymerization of methacrylonitrile initiated by triethylphosphine in dimethylformamide was studied. Experimental evidence for two mechanisms of termination reaction was obtained. By addition of water or alcohol in polymerizing system the rate of polymerization and molecular weight of polymethacrylon1itrile decrease, which proves the termination reaction to be bimolecular and proceed by interaction of the active carbanion with water or alcohol. The rate constant for termination of free anions with water was determined, k~,0 = 2.2 x 102 dm3 moP s-1• The termination reaction could not be excluded by purification and prolonged drying of all components of the system, which indicates that the second mechanism of termination is operative as well. Conductivity measurements gave evidence for a monomolecular spontaneous reaction leading to deactivation of the anion

АНАЛИТИЧЕСКИЙ СИНТЕЗ МЕТОДА НАВЕДЕНИЯ СВЕРХЗВУКОВОГО БЕСПИЛОТНОГО ЛЕТАТЕЛЬНОГО АППАРАТА НА ОСНОВЕ МНОГОМЕРНОЙ НЕЛИНЕЙНОЙ ДИНАМИЧЕСКОЙ МОДЕЛИ

A method of analytical synthesis of an optimal controller for the terminal control task of supersonic unmanned aerial vehicles based on synergetic approach to the design of control systems for nonlinear multidimensional dynamic objects is considered.The article provides analytical expressions describing the algorithm for control the velocity vector position of a supersonic UAV, the simulation results and the comparative analysis of the proposed control algorithm with the modified method of proportional navigation.Рассматривается аналитический синтез метода наведения для терминальной задачи управления сверхзвуковыми беспилотными летательными аппаратами на основе синергетического подхода к проектированию систем управления нелинейными многомерными динамическими объектами. Метод основан на введении в пространстве состояний синтезируемых систем оптимальных инвариантных многообразий – аттракторов, на которых наилучшим образом согласуются общие естественные (энергетические, механические, баллистические и др.) свойства объекта и частные требования конкретной технологической задачи. При этом обеспечиваются желаемые динамические характеристики и гарантируется асимптотическая устойчивость движения системы оптимальный регулятор – объект управления.Приводятся аналитические выражения, описывающие алгоритм управления положениемвектора скорости сверхзвукового беспилотного летательного аппарата, результаты математического моделирования и сравнительного анализа предлагаемого алгоритма управления с модифицированным методом пропорциональной навигации

Permanent annihilation of thermally activated defects which limit the lifetime of float-zone silicon

We have observed very large changes in the minority carrier lifetime when high purity float-zone (FZ) silicon wafers are subject to heat-treatments in the range of 200– 1100˚C. Recombination centres were found to become activated upon annealing at 450–700˚C, causing significant reductions in the bulk lifetime, detrimental for high efficiency solar cells and stable high powered devices. Photoluminescence imaging of wafers annealed at 500˚C revealed concentric circular patterns, with lower lifetimes occurring in the centre, and higher lifetimes around the periphery. Deep level transient spectroscopy measurements on samples extracted from the centre of an n-type FZ silicon wafer annealed at 500˚C revealed a large variety of defects with activation energies ranging between 0.16– 0.36eV. Our measurements indicate that vacancy related defects are causing the severe degradation in lifetime when FZ wafers are annealed at 450–700˚C. Upon annealing FZ silicon at temperatures >800°C, the lifetime is completely recovered, whereby the defect-rich regions vanish and do not reappear (permanently annihilated). Our results indicate that, in general, as-grown FZ silicon should not be assumed to be defect lean, nor can it be assumed that the bulk lifetime will remain stable during thermal processing, unless annealed at temperatures >1000°C

The Dynamics of Zeroth-Order Ultrasensitivity: A Critical Phenomenon in Cell Biology

It is well known since the pioneering work of Goldbeter and Koshland [Proc. Natl. Acad. Sci. USA, vol. 78, pp. 6840-6844 (1981)] that cellular phosphorylation- dephosphorylation cycle (PdPC), catalyzed by kinase and phosphatase under saturated condition with zeroth order enzyme kinetics, exhibits ultrasensitivity, sharp transition. We analyse the dynamics aspects of the zeroth order PdPC kinetics and show a critical slowdown akin to the phase transition in condensed matter physics. We demonstrate that an extremely simple, though somewhat mathematically "singular" model is a faithful representation of the ultrasentivity phenomenon. The simplified mathematical model will be valuable, as a component, in developing complex cellular signaling network theory as well as having a pedagogic value.Comment: 8 pages, 3 figure

90 Years to the Society of Anatomists, Histologists and Embryologists

Scientific research of the members of society in 90 years are diverse and they are numerous, they dedicated to questions of ethnic and integrative anthropology, to study of versions and anomalies in different systems of the organs of man, to study of cardiovascular and nervous systems in the aspect dependent on age and with the pathology, to development and the regeneration of the cardiovascular system, to questions of anatomical and anthropological equipment, comparative and veterinary anatomy. The members of society actively participated in the work of the forums of morphologists and clinicians. Was formed the sufficiently authoritative Rostov school of morphologists, whose representatives led departments in Russia cities and abroad

Energy state distributions of the P(b) centers at the (100), (110), and (111) Si/SiO(2) interfaces investigated by Laplace deep level transient spectroscopy

The energy distribution of the P(b) centers at the Si/SiO(2) interface has been determined using isothermal laplace deep level transient spectroscopy. For the (111) and (110) interface orientations, the distributions are similar and centered at 0.38 eV below the silicon conduction band. This is consistent with only P(b0) states being present. For the (100) orientation, two types of the interface states are observed: one similar to the (111) and (110) orientations while the other has a negative-U character in which the emission rate versus surface potential dependence is qualitatively different from that observed for P(b0) and is presumed to be P(b1). (C) 2008 American Institute of Physics. (DOI: 10.1063/1.2939001

ПОВЫШЕНИЕ ТОЧНОСТИ ОЦЕНИВАНИЯ КООРДИНАТ ОБЪЕКТА В МНОГОПОЗИЦИОННОЙ РАДИОЛОКАЦИОННОЙ СИСТЕМЕ С ПРИЕМНЫМ ПУНКТОМ ВОЗДУШНОГО БАЗИРОВАНИЯ

The dependence of the accuracy of the object's coordinates estimation on the relative position of transmitting and receiving points of the multi-position radar system was studied. A way to increase of the accuracy of the object's coordinates estimation for small elevation angles by placement of the one receiving positions on the aerial vehicle was proposed.Исследована зависимость точности оценки координат объекта от взаимного расположения передающего и приемных пунктов суммарно-разностно-дальномерной многопозиционной радиолокационной системы (МПРЛС). Предложен способ повышения точности оценивания координат для малых углов места за счет расположения одной из позиций на летательном средстве