50 research outputs found

    The structural and parametrical organization of elements of a power supply system in the conditions of network centrism

    Get PDF
    Purpose. Development of indicators of the structural and parametrical organization of effective active and adaptive system of service of power supply systems in the conditions of ideology of Smart Grid. Methodology. In the conditions of application of ideology of Smart Grid for increase of intellectualization of electrical power system there is a need of introduction of the principle of a network centrism in the structural and parametrical organization of elements of power supply systems that involves performance of conditions on implementation of provisions of the principle of Situational Awareness. The essence of this principle consists in that, information on a condition of system has to be presented in the form convenient for the analysis, recognition, transfer, distribution and storage, to be coordinated for flexible and optimum development at the subsystem and object-by-object levels. Results. Structural and parametrical optimization of elements of power supply systems in the conditions of a network centrism and the concept of SG involves use of provisions of the theory of systems and concepts of multicriteria optimizing synthesis. It is offered to use the modified adaptive indicator of the generalizing effect of synthesis of structure of active and adaptive system of service of power supply systems in the form of a difference of the generalizing effects: the introduced option of structure of system and basic. Originality. Introduction of an adaptive indicator of synthesis of system of service of power supply systems considers the concept of «service of system on the basis of a response» in the presence of false and true refusals. Practical value. Use of the specified indicator will allow to specify procedure of selection of competitive options for the purpose of definition of a set of admissible structures which meet the requirements of criterion function.В статье рассмотрены тенденции развития и принципы организации интеллектуальных энергосистем при введении понятия сетецентризма в условиях идеологии Smart Grid. В качестве решения задач указанной проблематики предлагается создание активно-адаптивной системы, реализующей концепцию «обслуживания системы на основе отклика»

    Einstein gravity as a 3D conformally invariant theory

    Get PDF
    We give an alternative description of the physical content of general relativity that does not require a Lorentz invariant spacetime. Instead, we find that gravity admits a dual description in terms of a theory where local size is irrelevant. The dual theory is invariant under foliation preserving 3-diffeomorphisms and 3D conformal transformations that preserve the 3-volume (for the spatially compact case). Locally, this symmetry is identical to that of Horava-Lifshitz gravity in the high energy limit but our theory is equivalent to Einstein gravity. Specifically, we find that the solutions of general relativity, in a gauge where the spatial hypersurfaces have constant mean extrinsic curvature, can be mapped to solutions of a particular gauge fixing of the dual theory. Moreover, this duality is not accidental. We provide a general geometric picture for our procedure that allows us to trade foliation invariance for conformal invariance. The dual theory provides a new proposal for the theory space of quantum gravity.Comment: 27 pages. Published version (minor changes and corrections

    Cell therapy for ischemic stroke

    Get PDF
    Stroke is the second, and in some countries the third cause of mortality in the population and one of the causes of disability in the adult population. According to statistics, in 2018, 15 million cases of stroke and 6 million deaths were diagnosed,The only currently approved treatments for acute stroke are intravenous tissue plasminogen activator (rtPA) and intra-arterial thrombectomy, which are used in less than 10% and 1% of patients, respectively.The literature review is devoted to the pathophysiology and molecular mechanisms of damage in cerebral ischemia. The modern concept of two strategies of cell therapy is discussed: neuroprotection and remodeling; the role of stem cells in reducing local and systemic inflammation, neurogenesis and angiogenesis, increasing neuronal plasticity, and protecting the blood-brain barrier, the role of paracrine factors and extracellular vesicles is shown.Methods of stem cell delivery are described: direct intracerebral transplantation, intraventricular and intrathecal, intravenous and intraarterial; the number of cells, their type and optimal delivery time depending on the acute, subacute and chronic periods of stroke. We also described recently designed the radially branched deployment (RBD) device and Cleveland multiport catheter for convection-enhanced delivery in which a cell-delivery catheter can be deployed at various angles and depths from a single longitudinal cannula. Finally, data on the completed 15 clinical trials from 2015 to the present, in which 513 patients took part, are presented. A detailed analysis of the efficacy and safety of cell therapy has been carried out

    СЕТЕЦЕНТРИЧЕСКИЕ ТЕХНОЛОГИИ УПРАВЛЕНИЯ РЕЖИМАМИ РАБОТЫ ТРЕХФАЗНОЙ СЕТИ

    Get PDF
    Purpose. The development of the control system for three-phase network is based on intelligent technologies of network-centric control of heterogeneous objects. The introduction of unmanned aerial vehicles for monitoring of three-phase network increases the efficiency of management. Methodology. The case of decomposition of the instantaneous capacities of the fixed and variable components for 3-wire system. The features of power balance for the different modes of its functioning. It should be noted that symmetric sinusoidal mode is balanced and good, but really unbalanced, if the standard reactive power is not zero. To solve the problem of compensation is sufficient knowledge of the total value of the inactive components of full power (value of the inactive power) without detail. The creation of a methodology of measurement and assessment will require knowledge of the magnitudes of each inactive component separately, which leads to the development of a unified approach to the measurement and compensation of inactive components of full power and the development of a generalized theory of power. Results. Procedure for the compensation of the current of zero sequence excludes from circuit the source, as the active component of instantaneous power of zero sequence, and a vector due to a current of zero sequence. This procedure is performed without time delay as it does not require integration. Only a 3–wire system with symmetrical voltage eliminates pulsations and symmetrization of the equivalent conductances of the phases of the task. Under asymmetric voltage, the power is different, its analysis requires the creation of a vector mathematical model of the energy processes of asymmetrical modes of 3–phase systems. Originality. The proposed method extends the basis of the vector method for any zero sequence voltages and shows that the various theories of instantaneous power three wired scheme due to the choice of a basis in a two-dimensional subspace. Practical value. The algorithm and software implementation for the decomposition of the zero sequence current, which allocated the procedure of obtaining null-balanced vectors of phase and interfacial voltage, calculation of active and inactive instantaneous power is zero balanced mode. The simulation results obtained in the software package Matlab by the method of visual programming in Simulink.Интеграция интеллектуальных и сетецентрических технологий в процесс управления режимами работы трехфазной сети обеспечивают оперативность компенсации нелинейностей в системе за счет ортогонального разложения тока и использования метода базисных функций для минимизации потерь

    The development of the theory of instantaneous power of three-phase network in terms of network centrism

    Get PDF
    Purpose. Information technologies allow multidimensional analysis of information about the state of the power system in a single information space in terms of providing network-centric approach to control and use of unmanned aerial vehicles as tools for condition monitoring of three-phase network. Methodology. The idea of energy processes in three independent (rather than four dependent) curves vector-functions with values in the arithmetic three-dimensional space adequately for both 4-wire and 3–wire circuits. The presence of zero sequence current structural (and mathematically) features a 4-wire scheme of energy from a 3-wire circuit. The zero sequence voltage caused by the displacement of the zero voltage phases. Offset zero in the calculations can be taken into account by appropriate selection of the reference voltages. Both of these energetic phenomena with common methodical positions are described in the framework of the general mathematical model, in which a significant role is played by the ort zero sequence. Results. Vector approach with a unified voice allows us to obtain and analyze new energy characteristics for 4–wire and 3–wire circuits in sinusoidal and non-sinusoidal mode, both in temporal and frequency domain. Originality. Symmetric sinusoidal mode is balanced, even with non-zero reactive power. The converse is not true. The mode can be balanced and unbalanced load. The mode can be balanced and unbalanced voltage. Practical value. Assessing balance in network mode and the impact of instantaneous power on the magnitude of the losses, will allow to avoid the appearance of zero sequence and, thus, to improve the quality of electricity.Обеспечение сетецентрического подхода к режиму управления трехфазной сетью и оценка сбалансированности режима сети с учетом влияния мгновенной мощности на величину потерь даст возможность исключить появление нулевой последовательности и, тем самым, повысить качество электроэнергии

    Network-centric technologies for control of three-phase network operation modes

    Get PDF
    Purpose. The development of the control system for three-phase network is based on intelligent technologies of network-centric control of heterogeneous objects. The introduction of unmanned aerial vehicles for monitoring of three-phase network increases the efficiency of management. Methodology. The case of decomposition of the instantaneous capacities of the fixed and variable components for 3-wire system. The features of power balance for the different modes of its functioning. It should be noted that symmetric sinusoidal mode is balanced and good, but really unbalanced, if the standard reactive power is not zero. To solve the problem of compensation is sufficient knowledge of the total value of the inactive components of full power (value of the inactive power) without detail. The creation of a methodology of measurement and assessment will require knowledge of the magnitudes of each inactive component separately, which leads to the development of a unified approach to the measurement and compensation of inactive components of full power and the development of a generalized theory of power. Results. Procedure for the compensation of the current of zero sequence excludes from circuit the source, as the active component of instantaneous power of zero sequence, and a vector due to a current of zero sequence. This procedure is performed without time delay as it does not require integration. Only a 3–wire system with symmetrical voltage eliminates pulsations and symmetrization of the equivalent conductances of the phases of the task. Under asymmetric voltage, the power is different, its analysis requires the creation of a vector mathematical model of the energy processes of asymmetrical modes of 3–phase systems. Originality. The proposed method extends the basis of the vector method for any zero sequence voltages and shows that the various theories of instantaneous power three wired scheme due to the choice of a basis in a two-dimensional subspace. Practical value. The algorithm and software implementation for the decomposition of the zero sequence current, which allocated the procedure of obtaining null-balanced vectors of phase and interfacial voltage, calculation of active and inactive instantaneous power is zero balanced mode. The simulation results obtained in the software package Matlab by the method of visual programming in Simulink.Интеграция интеллектуальных и сетецентрических технологий в процесс управления режимами работы трехфазной сети обеспечивают оперативность компенсации нелинейностей в системе за счет ортогонального разложения тока и использования метода базисных функций для минимизации потерь

    Biochemical markers of vital biodestruction in common oak (Quercus robur)

    Get PDF
    The wood of the common oak (Quercus robur L.) has high mechanical strength, elasticity and resistance to fracture. However, constitutional stability is not always able to provide the plants with reliable protection from wood-decay fungi, and the initial stages of biodegradation are difficult to determine. Therefore, this study concerns research on appropriate biochemical markers for early diagnostics of wood defects. The total content of phenolic compounds in leaves and wood was determined by a spectrophotometer Optizen Pop using Folin & Ciocalteu’s phenol reagent; the flavonoid content in leaves – by adding solutions of aluminum chloride and sodium acetate to methanolic extracts; catechins content – by the reaction with vanillin reagent; the concentration of phenolic antioxidants – by Brand Williams; chlorophyll and carotenoids’ contents in leaves – by the formula for methanol extracts; the qualitative composition of phenolic compounds – by high performance liquid chromatography and highly effective thin-layer chromatography. During the planned felling of oak trees on the territory of the Boyar Forest Research Station, trees were found with signs of brown streak and biodestruction of wood. Brown streak in wood is caused by a polycondensation of phenolic compounds, which are deposited on the internal surfaces of tracheal elements. In cases of an increase in the total amount of oxidized polyphenols, the cell walls are also stained. Active oxidation processes in wood have a systemic nature for the plants and affect the physiological state of the assimilation apparatus. We determined that in leaves of the trees with signs of brown streak the total phenol content increases in comparison with the control by 1.6 times, as well as flavonoid and catechin content. Our research has shown that the complex of plastid pigments in common oak leaves does not significantly change in the early stages of destructive processes. Increase of brown streak and appearance of rot in wood are associated with slight increase in chlorophyll a to b ratio in leaves. Chromatographic profiling of the leaves showed that the presence of brown streak changes the content of individual phenolic compounds. The trees with brown rot have more substances with UV spectrum characteristic for kaempferol glycosides compared to the control. The results have shown that the biochemical profiles of the trees with signs of brown streak and brown rot differ from the control by the composition of low and medium polar compounds. The absence or presence of some individual phenolic components and their ratio in the leaves are considered as biochemical markers of hidden wood defects

    СЕТЕЦЕНТРИЧЕСКАЯ ОПТИМИЗАЦИЯ ОПЕРАТИВНОГО ОБСЛУЖИВАНИЯ ЭЛЕМЕНТОВ ЭНЕРГОСИСТЕМЫ

    Get PDF
    Purpose. Development of precision selection criteria of options of technical realization of effective active and adaptive system of expeditious service of elements of a power supply system in the conditions of network-centric management. Methodology. In development of power supply systems their evolution from the elementary forms using elementary network technologies and models of interactions in power to more irregular shapes within the concept of Smart Grid with elements of network-centric character is observed. This direction is based on Internet-technologies of the last generation, and realize models of power activity which couldn't be realized before. Results. The number of possible options of active and adaptive system of expeditious service of elements of a power supply system is usually rather big and it is difficult to choose the acceptable option by direct search. Elimination of admissible options of the technical realization constructed on the principles of a network centrism means application of the theory of multicriteria optimization from a position of discrete programming. The basis of procedure of elimination is made by algorithm of an assessment of system by criterion of accuracy. Originality. The case of an assessment of the precision characteristic of system at restrictions for the set accuracy is connected with need of decomposition of requirements of all system in general and on separate subsystems. For such decomposition the ratios connecting the accuracy of functioning of a separate subsystem with variations of parameters of all system, and also with precision characteristics of subsystems of the lower levels influencing this subsystem are received. Practical value. In the conditions of the network-centric organization of management of expeditious service of elements of a power supply system elimination of options of subsystems when using precision criterion allows to receive the maximum number of essentially possible options of system of service taking into account the accepted service strategy.В статье уделено внимание вопросам использования сетецентрического подхода при формировании активно-адаптивной системы оперативного обслуживания элементов энергосистемы в условиях идеологии Smart Grid. Определен точностной критерий отсева вариантов технической реализации этой системы, реализующей концепцию «обслуживания на основе отклика».У статті приділена увага питанням використання сетецентричного підходу при формуванні активно-адаптивної системи оперативного обслуговування елементів енергосистеми в умовах ідеології Smart Grid. Визначений точносний критерій відсіювання варіантів технічної реалізації цієї системи, що реалізує концепцію «обслуговування на основі відклику»

    Singularity resolution depends on the clock

    No full text
    We study the quantum cosmology of a flat Friedmann–Lemaître–Robertson–Walker Universe filled with a (free) massless scalar field and a perfect fluid that represents radiation or a cosmological constant whose value is not fixed by the action, as in unimodular gravity. We study two versions of the quantum theory: the first is based on a time coordinate conjugate to the radiation/dark energy matter component, i.e., conformal time (for radiation) or unimodular time. As shown by Gryb and Thébault, this quantum theory achieves a type of singularity resolution; we illustrate this and other properties of this theory. The theory is then contrasted with a second type of quantisation in which the logarithm of the scale factor serves as time, which has been studied in the context of the 'perfect bounce' for quantum cosmology. Unlike the first quantum theory, the second one contains semiclassical states that follow classical trajectories and evolve into the singularity without obstruction, thus showing no singularity resolution. We discuss how a complex scale factor best describes the semiclassical dynamics. This cosmological model serves as an illustration of the problem of time in quantum cosmology

    Quantum Machian Time in Toy Models of Gravity

    Get PDF
    General Relativity on closed spatial topologies can be derived, using a technique called "best-matching", as an evolving 3-geometry subject to constraints. These constraints can be thought of as a way of imposing temporal and spatial relationalism. The same type of constraints can be used in non-relativistic particle models to produce relational theories that suffer from the same Problem of Time as that encountered in General Relativity. As a result, these simple toy models are well suited for studying the Problem of Time in quantum gravity. In this paper, a version of these particle models is studied where we "best-match" the time translational invariance of the theory. Using insights gained from this procedure, we can move back and forth between absolute and relational time by changing the way in which the relational fields are varied. We then proceed to quantize this theory using Dirac and path integral quantizations. We discover that one of the constraints of the theory, which we call the Mach constraint, is responsible for removing the dependence of the theory on a background structure. It is this Mach constraint that is responsible for making the theory temporally relational. Because of the deep relationship between these models and General Relativity, this work may shed new light on the Problem of Time in quantum gravity and how one might expect time to emerge on quantum subsystems of the universe.Comment: 27 pages, references added, typos fixed, additional comments added to abs/intro/concl, journal ref adde
    corecore