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R, Rakesh, Krishna Raj Ramachandran, Apurv Kumar Yadav, K. Gopakumar, Loganathan Umanand i Kouki Matsuse. "A Switched Capacitive Filter-Based Harmonic Elimination Technique by Generating a 30-Sided Voltage Space Vector Structure for IM Drive". IEEE Transactions on Power Electronics 35, nr 3 (marzec 2020): 2402–10. http://dx.doi.org/10.1109/tpel.2019.2930280.
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Jiménez Fernández, E., i E. A. Sánchez Pérez. "Lattice Copies ofℓ2inL1of a Vector Measure and Strongly Orthogonal Sequences". Journal of Function Spaces and Applications 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/357210.
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Letmbe anℓ2-valued (countably additive) vector measure and consider the spaceL2(m) of square integrable functions with respect tom. The integral with respect tomallows to define several notions of orthogonal sequence in these spaces. In this paper, we center our attention in the existence of stronglym-orthonormal sequences. Combining the use of the Kadec-Pelczyński dichotomy in the domain space and the Bessaga-Pelczyński principle in the range space, we construct a two-sided disjointification method that allows to prove several structure theorems for the spacesL1(m) andL2(m). Under certain requirements, our main result establishes that a normalized sequence inL2(m) with a weakly null sequence of integrals has a subsequence that is stronglym-orthonormal inL2(m∗), wherem∗is anotherℓ2-valued vector measure that satisfiesL2(m) = L2(m∗). As an application of our technique, we give a complete characterization of when a space of integrable functions with respect to anℓ2-valued positive vector measure contains a lattice copy ofℓ2.
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Raj R, Krishna, K. Gopakumar, Apurv Kumar Yadav, L. Umanand, Mariusz Malinowski i Wojciech Jarzyna. "A Twelve Concentric Multilevel Twenty-Four Sided Polygonal Voltage Space Vector Structure for Variable Speed Drives". IEEE Transactions on Power Electronics 34, nr 10 (październik 2019): 9906–15. http://dx.doi.org/10.1109/tpel.2019.2892329.
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Saikia, D. J., W. Junor, T. J. Cornwell, T. W. B. Muxlow i P. Shastri. "A VLA and MERLIN study of extragalactic radio sources with one-sided structure". Monthly Notices of the Royal Astronomical Society 245, nr 3 (1.08.1990): 408. http://dx.doi.org/10.1093/mnras/245.3.408.
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Summary To investigate the nature of extragalactic radio sources with extended emission on only one side of the active nucleus, we have observed a sample of suspected candidates with both the VLA and MERLIN. In this paper, we present observations of 13 sources which were either suspected of being ‘one-sided’ or were known to have lobes of very different surface brightnesses. Many of the candidates were found to have emission on both sides of the nucleus. Using our observations as well as those available in the literature, we have compiled a sample of 4C quasars having one-sided radio structure. We have then compared some of their properties with a sample of 4C quasars which are two-sided, in order to determine whether their apparently onesided structure is due to relativistic beaming in sources inclined at small angles to the line-of-sight. We find that the median values of fc, the fraction of emission from the core used as a statistical measure of source orientation, and l, their projected linear sizes are consistent with the hypothesis that the one-sided quasars are seen at smaller angles to the line-of-sight than the two-sided ones. We also suggest that the ϕ-fc relation for quasars, where ϕ is the angle between the core polarization vector and the overall radio axis, is consistent with this model, and discuss how the lobe depolarization properties may be useful for further investigations of this interpretation. The velocities required to explain the apparently one-sided quasars in the relativistic beaming framework are in the range of ˜ 0.2-0.8 c. The scarcity of highluminosity, Fanaroff-Riley class II radio galaxies with one-sided structure is consistent with the suggestion that they are at larger angles to the line-of-sight than quasars. In this case, the core-dominated radio galaxies are possibly the lowluminosity, Fanaroff-Riley class I radio galaxies seen at small angles to the line-ofsight, manifesting themselves as BL Lac objects in the more extreme cases.
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Krishna, Raj R., K. Gopakumar, Mathews Boby, Apurv Kumar Yadav, Leopoldo Garcia Franquelo i Sheldon S. Williamson. "Multilevel 24-Sided Polygonal Voltage-Space-Vector Structure Generation for an IM Drive Using a Single DC Source". IEEE Transactions on Industrial Electronics 66, nr 2 (luty 2019): 1023–31. http://dx.doi.org/10.1109/tie.2018.2831189.
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Yadav, Apurv Kumar, Mathews Boby, Sumit Kumar Pramanick, K. Gopakumar, Loganathan Umanand i Leopoldo G. Franquelo. "Generation of High-Resolution 12-Sided Voltage Space Vector Structure Using Low-Voltage Stacked and Cascaded Basic Inverter Cells". IEEE Transactions on Power Electronics 33, nr 9 (wrzesień 2018): 7349–58. http://dx.doi.org/10.1109/tpel.2017.2764541.
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Mendes-Gonçalves, Suzana, i R. P. Sullivan. "The Ideal Structure of Semigroups of Linear Transformations with Lower Bounds on Their Nullity or Defect". Algebra Colloquium 17, nr 01 (marzec 2010): 109–20. http://dx.doi.org/10.1142/s1005386710000131.
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Suppose V is an infinite-dimensional vector space and let T(V) denote the semigroup (under composition) of all linear transformations of V. In this paper, we study the semigroup OM(p,q) consisting of all α ∈ T(V) for which dim ker α ≥ q and the semigroup OE(p,q) of all α ∈ T(V) for which codim ran α ≥ q, where dim V = p ≥ q ≥ ℵ0. It is not difficult to see that OM(p,q) and OE(p,q) are a right ideal and a left ideal of T(V), respectively, and using these facts, we show that they belong to the class of all semigroups whose sets of bi-ideals and quasi-ideals coincide. Also, we describe Green's relations and the two-sided ideals of each semigroup, and determine its maximal regular subsemigroup. Finally, we determine some maximal right cancellative subsemigroups of OE(p,q).
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Lepoittevin, Christophe, i Olivier Leynaud. "Resolution of a modulated structure by electron and powder X-ray diffraction". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C928. http://dx.doi.org/10.1107/s2053273314090718.
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These past few years, many new structures have been solved using electron diffraction methods: zone axis precession electron diffraction (PED) and tomography in reciprocal space. Both methods enable to reduce importantly the multiple scattering, so that the reflection intensities can be used for structure determination by direct methods. The ferrite Sr25Fe30O77 belongs to a family of phases whose structures consist of an intergrowth of m perovskite layers with complex rocksalt type layers [1,2]. The compound of interest is the member m = 4 of this family and its structure has been solved by combining both electron diffraction methods cited above. This oxide crystallizes in an orthorhombic system with the sub-cell parameters a ≍ b ≍ 5.4 Å and c ≍ 42 Å in a F type lattice. The structure exhibits modulation along a axis with a modulation vector q = 2/5 a. The commensurate nature of the modulation enables to describe the structure in a supercell with the cell parameters a ≍ 27 Å, b ≍ 5.4 Å and c ≍ 42 Å. PED patterns were recorded in zone axis with a Spinning Star unit using a precession angle of 20. The intensities were extracted with CRISP software and the resulting dataset was then implemented in SIR2008 for structure solution. The tomography data collection, recorded by tilting manually every 0.5 degree from -30 to +30 degrees, was inserted in a "3D Electron Diffraction Tomography" software, which reconstructs the 3D reciprocal space and extracts automatically the reflection intensities. The intensity file was then used on SIR2008 for structure determination. In order to confirm and refine the structural model, a powder X-ray diffraction pattern was performed on a laboratory diffractometer with Cu Ka1 radiation. Cell parameters were refined with the WinPlotr and FullProf Softwares using both LeBail and Rietveld methods [3]. The structural model obtained with electron diffraction data was tried and confirmed as the correct structure by the Rietveld refinements.
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Stepan, Vasyliv, i Ternova Kateryna. "Study of the flow structure during the injection of detonation products into the supersonic nozzle". System technologies 2, nr 145 (11.05.2023): 11–18. http://dx.doi.org/10.34185/1562-9945-2-145-2023-02.
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The gradual unloading of the space stage by undocking objects from it or an emer-gency situation due to the undocking of one of the spacecraft leads to mass asymmetry. In outer space there is also the problem of the collision of a space object with elements of space debris. Therefore, the relevance of the topic of this work is determined by the need to develop a system for avoiding the collision of a rocket with elements of space de-bris and controlling the flight, observing the programmed trajectory of movement. The gas-dynamic aircraft system is characterized by the highest speed control. Injection of detonation products into the supercritical part of the nozzle was used as a gas-dynamic system. Modeling was carried out in the SolidWorks application software package. The purpose of the work is to develop alternative methods of the thrust vector control of the upper stage rocket engine. The scheme of the system for the thrust vector control of a rocket engine by the effect of a detonation wave on the gas flow in its nozzle has been developed. The simulation was carried out in a non-stationary flat model at angles to the axis of the combustion chamber of 90°, 60°, 45°, 30° and parallel to the axis, - 0°. The location of the detonation gas generator was near the nozzle section. Numerical simulation revealed that the impact of the detonation wave on the main gas flow in the nozzle causes two power factors. The first force factor is due to the reactive force when detonation products are thrown into the nozzle and on the wall of the high pressure zone where the detonation gas generator is located. The second force factor is due to the change in pressure distribution on the nozzle surface, where high pressure zone creates reflecting on it. The dependence of the relative lateral force on the injection angle of detonation products into the combustion chamber over time has been obtained. The structure of the flow according to the patterns of the velocity distribution in the nozzle during the injection of detonation products is also considered. In cases when the injec-tion is blown at 900 and 450, the release of detonation products initiates a shock wave of high intensity, which moves against the supersonic flow, retarding it. The developed scheme can be used for maneuvering the upper stage of a prospective launch vehicle to avoid its collision with elements of space debris.
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Belenkaya, E. S., I. I. Alexeev, M. S. Blokhina, S. W. H. Cowley, S. V. Badman, V. V. Kalegaev i M. S. Grigoryan. "IMF dependence of the open-closed field line boundary in Saturn's ionosphere, and its relation to the UV auroral oval observed by the Hubble Space Telescope". Annales Geophysicae 25, nr 5 (4.06.2007): 1215–26. http://dx.doi.org/10.5194/angeo-25-1215-2007.
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Abstract. We study the dependence of Saturn's magnetospheric magnetic field structure on the interplanetary magnetic field (IMF), together with the corresponding variations of the open-closed field line boundary in the ionosphere. Specifically we investigate the interval from 8 to 30 January 2004, when UV images of Saturn's southern aurora were obtained by the Hubble Space Telescope (HST), and simultaneous interplanetary measurements were provided by the Cassini spacecraft located near the ecliptic ~0.2 AU upstream of Saturn and ~0.5 AU off the planet-Sun line towards dawn. Using the paraboloid model of Saturn's magnetosphere, we calculate the magnetospheric magnetic field structure for several values of the IMF vector representative of interplanetary compression regions. Variations in the magnetic structure lead to different shapes and areas of the open field line region in the ionosphere. Comparison with the HST auroral images shows that the area of the computed open flux region is generally comparable to that enclosed by the auroral oval, and sometimes agrees in detail with its poleward boundary, though more typically being displaced by a few degrees in the tailward direction.
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Pegram, G. G. S., i A. N. Clothier. "Downscaling rainfields in space and time, using the String of Beads model in time series mode". Hydrology and Earth System Sciences 5, nr 2 (30.06.2001): 175–86. http://dx.doi.org/10.5194/hess-5-175-2001.
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Abstract. The String of Beads model is a space-time model of rainfields measured by weather radar. It is here driven by two auto-regressive time series models, one at the image scale, the other at the pixel scale, to model the temporal correlation structure of the wet-period process. The marginal distribution of the pixel scale intensities on a given radar-rainfall image is described by a log-normal distribution. The spatial dependence structure of each image is defined by a power spectrum approximated by a power law function with a negative exponent. It is demonstrated that this stochastic modelling approach is valid because the images sampled are effectively stationary above a scale of 30 km, which is less than a quarter of the image width. By advecting a simulated sequence of images along the same cumulative advection vector as the observed event and matching the image-scale statistics of each simulated image with those of the corresponding observed image, a simulated sequence of plausible images is generated which mimics (has the same space-time statistics as) the observed event but differs from it in detail. Aggregating the pixel scale intensities in each sequence over a number of time and space intervals and then comparing their spatial and temporal statistics, demonstrates that the model captures the intermediate scale behaviour well, showing satisfactorily its ability to downscale rainfall in space and time. The model thus has potential as an operational space-time model of rainfields. Keywords: Space-time, rainfield modelling, weather radar, multifractals, Gaussian random fields
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Kuang, Wenhui, Shu Zhang, Xiaoyong Li i Dengsheng Lu. "A 30 m resolution dataset of China's urban impervious surface area and green space, 2000–2018". Earth System Science Data 13, nr 1 (14.01.2021): 63–82. http://dx.doi.org/10.5194/essd-13-63-2021.
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Abstract. Accurate and timely maps of urban underlying land properties at the national scale are of significance in improving habitat environment and achieving sustainable development goals. Urban impervious surface (UIS) and urban green space (UGS) are two core components for characterizing urban underlying environments. However, the UIS and UGS are often mosaicked in the urban landscape with complex structures and composites. The “hard classification” or binary single type cannot be used effectively to delineate spatially explicit urban land surface property. Although six mainstream datasets on global or national urban land use and land cover products with a 30 m spatial resolution have been developed, they only provide the binary pattern or dynamic of a single urban land type, which cannot effectively delineate the quantitative components or structure of intra-urban land cover. Here we propose a new mapping strategy to acquire the multitemporal and fractional information of the essential urban land cover types at a national scale through synergizing the advantage of both big data processing and human interpretation with the aid of geoknowledge. Firstly, the vector polygons of urban boundaries in 2000, 2005, 2010, 2015 and 2018 were extracted from China's Land Use/cover Dataset (CLUD) derived from Landsat images. Secondly, the national settlement and vegetation percentages were retrieved using a sub-pixel decomposition method through a random forest algorithm using the Google Earth Engine (GEE) platform. Finally, the products of China's UIS and UGS fractions (CLUD-Urban) at a 30 m resolution were developed in 2000, 2005, 2010, 2015 and 2018. We also compared our products with six existing mainstream datasets in terms of quality and accuracy. The assessment results showed that the CLUD-Urban product has higher accuracies in urban-boundary and urban-expansion detection than other products and in addition that the accurate UIS and UGS fractions were developed in each period. The overall accuracy of urban boundaries in 2000–2018 are over 92.65 %; and the correlation coefficient (R) and root mean square errors (RMSEs) of UIS and UGS fractions are 0.91 and 0.10 (UIS) and 0.89 and 0.11 (UGS), respectively. Our result indicates that 71 % of pixels of urban land were mosaicked by the UIS and UGS within cities in 2018; a single UIS classification may highly increase the mapping uncertainty. The high spatial heterogeneity of urban underlying covers was exhibited with average fractions of 68.21 % for UIS and 22.30 % for UGS in 2018 at a national scale. The UIS and UGS increased unprecedentedly with annual rates of 1605.56 and 627.78 km2 yr−1 in 2000–2018, driven by fast urbanization. The CLUD-Urban mapping can fill the knowledge gap in understanding impacts of the UIS and UGS patterns on ecosystem services and habitat environments and is valuable for detecting the hotspots of waterlogging and improving urban greening for planning and management practices. The datasets can be downloaded from https://doi.org/10.5281/zenodo.4034161 (Kuang et al., 2020a).
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Bandoli, Giuliano, Jan Bergman, Kurt J. Irgolic, Antonio Grassi i Giuseppe C. Pappalardo. "Solid State and Solution Conformation of Di-2-thienyl Telluride: X-Ray Structure and Dipole Moment Studies". Zeitschrift für Naturforschung B 40, nr 9 (1.09.1985): 1157–60. http://dx.doi.org/10.1515/znb-1985-0911.
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The crystal and molecular structure of di-2-thienyl telluride was determined by X-ray analysis. Crystal (monoclinic) data were: a = 9.526(4), b = 6.252(4), c - 16.302(5) Å; β = 97.29(3)°, Z = 4, space group P21/c. Hydrogen bonds are absent and only van der Waals forces are determining crystal packing. The Cring-Te bond distances suggest little conjugation of Te atom with the rings. Comparisons with published structures for Car-X-Car (X = chalcogen) type molecules revealed that the C (l)-Te-C(5) angle takes the lowest value (95.6°) in the molecule understudy. The remaining bond lengths and angles are close to standard values. The molecular conformation found in the crystal is “butterfly-like” , with thienyl ring planes nearly perpendicular to the C(l)-Te-C(5) plane and the S atoms distal to each other. Dipole moment was measured for di-2-thienyl telluride in benzene solution (μ = 1.18 D at 30°). This value, which was interpreted via classical vector addition method in terms of rotation angles about C(l)-Te and C(5)-Te bonds, showed that the molecular conformation found in the crystalline state is retained in solution.
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Sato, Taku, Yusuke Nambu, Tao Hong, Masaaki Matsuda, Huibo Cao, Masataka Kinoshita, Shinichiro Seki, Shintaro Ishiwata i Yoshinori Tokura. "Magnetic structure of the chiral triangular magnet MnSb2O6". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C387. http://dx.doi.org/10.1107/s2053273314096120.
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Incommensurate helical (or cycloidal) magnetic structure may have left- and right-wound states (helicity), which are in principle equally populated in a magnet with inversion symmetry. In addition, for a Heisenberg triangular antiferromagnet, clockwise and counter-clockwise rotations of the 120 degree spin structure provide another intriguing degree of freedom. Hence, a triangular magnet that has incommensurate helical ordering along the stacking direction will show intriguing interplay of the helicity (of the helical structure) and chirality (in the triangular plane). Such phenomenon is, however, rarely studied in the past since only one example, the Ba3NbFe3Si2O14 langathite, has been known to date [1]. In this work, we study MnSb2O6, which consists of distorted triangular lattice stacking along the c-axis [2,3]. MnSb2O6 belongs to the space group P321, and hence lacks inversion symmetry. Due to this fact, unique selection of the helicity and chirality may be expected. However, the earlier studies were carried out using unpolarized neutron diffraction with mostly the powder sample, and thus helicity and chirality selection cannot be concluded. Here, we have performed single-crystal diffraction experiment using polarized neutrons in addition to the unpolarized ones, and have succeeded in determination of the magnetic structure of MnSb2O6. The resulting magnetic structure is nearly cycloidal with the magnetic modulation vector q = (0, 0, 0.182) (see figure below). The spin rotation plane is, however, inclined from the ac-plane toward the b-axis for approximately 30 degrees. Polarization analysis indicates that both the helicity of the (nearly-) cycloidal structure and chirality of the in-plane 120 degree structure are uniquely selected. The 30 degree inclination from the ac-plane is a key finding of this work, allowing new kind of multiferroicity in this material.
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Wang, Xueyuan, Hongpo Zhang, Zongmin Wang, Yaqiong Qiao, Jiangtao Ma i Honghua Dai. "Con&Net: A Cross-Network Anchor Link Discovery Method Based on Embedding Representation". ACM Transactions on Knowledge Discovery from Data 16, nr 2 (30.04.2022): 1–18. http://dx.doi.org/10.1145/3469083.
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Cross-network anchor link discovery is an important research problem and has many applications in heterogeneous social network. Existing schemes of cross-network anchor link discovery can provide reasonable link discovery results, but the quality of these results depends on the features of the platform. Therefore, there is no theoretical guarantee to the stability. This article employs user embedding feature to model the relationship between cross-platform accounts, that is, the more similar the user embedding features are, the more similar the two accounts are. The similarity of user embedding features is determined by the distance of the user features in the latent space. Based on the user embedding features, this article proposes an embedding representation-based method Con&Net(Content and Network) to solve cross-network anchor link discovery problem. Con&Net combines the user’s profile features, user-generated content (UGC) features, and user’s social structure features to measure the similarity of two user accounts. Con&Net first trains the user’s profile features to get profile embedding. Then it trains the network structure of the nodes to get structure embedding. It connects the two features through vector concatenating, and calculates the cosine similarity of the vector based on the embedding vector. This cosine similarity is used to measure the similarity of the user accounts. Finally, Con&Net predicts the link based on similarity for account pairs across the two networks. A large number of experiments in Sina Weibo and Twitter networks show that the proposed method Con&Net is better than state-of-the-art method. The area under the curve (AUC) value of the receiver operating characteristic (ROC) curve predicted by the anchor link is 11% higher than the baseline method, and Precision@30 is 25% higher than the baseline method.
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Neneng, Neneng, Kusworo Adi i Rizal Isnanto. "Support Vector Machine Untuk Klasifikasi Citra Jenis Daging Berdasarkan Tekstur Menggunakan Ekstraksi Ciri Gray Level Co-Occurrence Matrices (GLCM)". JURNAL SISTEM INFORMASI BISNIS 6, nr 1 (30.11.2016): 1. http://dx.doi.org/10.21456/vol6iss1pp1-10.
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Texture is one of the most important features for image analysis, which provides informations such as the composition of texture on the surface structure, changes of the intensity, or brightness. Gray level co-occurence matrix (GLCM) is a method that can be used for statistical texture analysis. GLCM has proven to be the most powerful texture descriptors used in image analysis. This study uses the four-way GLCM 0o, 45o, 90o, and 135o. Support vector machine (SVM) is a machine learning that can be used for image classification. SVM has a high generalization capability without any requirement of additional knowledge, even with the high dimension of the input space. The data used in this study are the image of goat meat, buffalo meat, horse meat, and beef with shooting distance 20 cm, 30 cm and 40 cm. The result of this study shows that the best recognition rate of 87.5% was taken at a distance of 20 cm with neighboring pixels distance d = 2 in the direction GLCM 135o.
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Wu, Yue-Liang. "Theory of quantum gravity beyond Einstein and space-time dynamics with quantum inflation". International Journal of Modern Physics A 30, nr 28n29 (20.10.2015): 1545002. http://dx.doi.org/10.1142/s0217751x15450025.
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In this talk, I present a theory of quantum gravity beyond Einstein. The theory is established based on spinnic and scaling gauge symmetries by treating the gravitational force on the same footing as the electroweak and strong forces. A bi-frame space-time is initiated to describe the laws of nature. One frame space-time is a globally flat coordinate Minkowski space-time that acts as an inertial reference frame for the motions of fields, the other is a locally flat non-coordinate Gravifield space-time that functions as an interaction representation frame for the degrees of freedom of fields. The Gravifield is sided on both the globally flat coordinate space-time and locally flat non-coordinate space-time and characterizes the gravitational force. Instead of the principle of general coordinate invariance in Einstein theory of general relativity, some underlying principles with the postulates of coordinate independence and gauge invariance are motivated to establish the theory of quantum gravity. When transmuting the Gravifield basis into the coordinate basis in Minkowski space-time, it enables us to obtain equations of motion for all quantum fields and derive basic conservation laws for all symmetries. The gravity equation is found to be governed by the total energy–momentum tensor defined in the flat Minkowski space-time. When the spinnic and scaling gauge symmetries are broken down to a background structure that possesses the global Lorentz and scaling symmetries, we arrive at a Lorentz invariant and conformally flat background Gravifield space-time that is characterized by a cosmic vector with a non-zero cosmological mass scale. We also obtain the massless graviton and massive spinnon. The resulting universe is in general not isotropic in terms of conformal proper time and turns out to be inflationary in light of cosmic proper time. The conformal size of the universe has a singular at the cosmological horizon to which the cosmic proper time must be infinitely large. We show a mechanism for quantum inflation caused by the quantum loop contributions. The Gravifield behaves as a Goldstone-like field that transmutes the local spinnic gauge symmetry into the global Lorentz symmetry, which makes the spinnic gauge field becomes a hidden gauge field. As a consequence, the bosonic gravitational interactions can be described by the Goldstone-like Gravimetric field and space-time gauge field. The Einstein theory of general relativity is expected to be an effective low energy theory. Two types of gravity equation are resulted, one is the extension to Einstein’s equation of general relativity, and the other is a new type of gravitational equation that characterizes the spinnon dynamics.
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Berestova, T. F., i A. V. Mikhailova. "Methodology of a spatial approach in library science: prevalence and specificity of applying". Bibliosphere, nr 4 (30.12.2017): 51–61. http://dx.doi.org/10.20913/1815-3186-2017-4-51-61.
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Space is one of the basic categories of philosophy having extensive operational and analytical capabilities. Nowadays the specificity of different types of spaces is studied, and the methodology of a spatial approach has become recognized as an effective method of knowledge in various sciences: philosophy, philology, pedagogics and psychology, political science, sociology, art history and cultural studies, economics and law, technical and natural sciences (physics, mathematics, biology, chemistry). As a special tool, the spatial approach is included in the scientific-educational store of documentary communication cycle’s sciences. To proof this statement authors examined an array of dissertations on library science and bibliography. A vector of cognitive activity, formed in librarian works of last 20-30 years, was directed on researching a spatial-information subject, as well as related to an «information space» phenomenon. However, many scientists, focusing on spatial terminology, have not deepened theoretical aspects and set tasks to detect an entity and structure of the information space without trying to offer its definition. Nevertheless, after representation theoretical and methodological foundations for studying information space scientists by T. F. Berestova in her doctoral dissertation researches began operating spatial terminology more confidently. Works’ analysis in library science allowed concluding that studying information or any other space researchers always focus their attention on investigating the interaction of the subject, which simultaneously acts as a part and as a creator of the space with other subjects and objects within it. This interaction provides course of integrative processes between subjects. The library science has already studied some form of interaction, identified a number of areas of integration processes, which are involved and initiated by the library. Thus, the analysis of works revealing the spatial issues enabled to summarize the methodology and to identify some common theoretical and methodological positions, which should be relied while developing a new epistemological tool in library science: methodology of the spatial approach. This article offers recommendations to use the spatial approach in library science and bibliographic researches.
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Bondar, V. S., D. R. Abashev i D. Yu Fomin. "COMPARATIVE ANALYSIS OF PLASTICITY THEORIES UNDER COMPLEX LOADING". Problems of Strength and Plasticity 84, nr 4 (2022): 493–510. http://dx.doi.org/10.32326/1814-9146-2022-84-4-493-510.
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Variants of theories of plastic flow under combined hardening, widely used in practical calculations of structures, are considered. A comparative analysis of the variants of theories under complex loading along plane and spatial deformation trajectories is carried out, covering a wide range of trajectories from multi-link polylines to curved trajectories of variable curvature and torsion. Trajectories from medium to large curvature and torsion are considered. The analysis of the research results is carried out in the vector space of A.A. Ilyushin. The plane trajectories of deformations in the form of a square and a curved trajectory of variable curvature in the form of an astroid are considered, as well as the spatial trajectory of deformations of variable curvature and torsion in the form of a helix. The results of calculations are compared with the results of experimental studies on stress response trajectories, scalar and vector properties. Variants of the theories are considered: the isotropic hardening model; the Ishlinski–Prager–Kadashevich–Novozhilov model (linear kinematic hardening + isotropic hardening); a model similar to the Ono–Wang model; the Armstrong-Frederick-Kadashevich model; the Shabosh model with three Armstrong–Frederick–Kadashevich evolutionary equations; the Temis model based on the invariant theory of plasticity; the Cooper model with a three-membered structure the evolutionary equation for kinematic hardening. The material parameters (functions), the closing versions of the theories of plasticity are given. Satisfactory compliance with the experiment for all deformation trajectories is achieved by calculations based on the Shabosh and the Bondar models – the difference between the results of calculations and experiments does not exceed 30% with the best correspondence to the experiment of the Bondar model. It should be noted that the Bondar plasticity model is closed by three parameters of anisotropic hardening and one function of isotropic hardening, and the Shabosh model is closed by six parameters and one function.
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Bondar, V. S., D. R. Abashev i D. Ju Fomin. "Theories of plasticity under complex loading along flat trajectories of deformations". PNRPU Mechanics Bulletin, nr 3 (15.12.2021): 35–47. http://dx.doi.org/10.15593/perm.mech/2021.3.04.
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The paper considers variants of theories of plastic flow with combined hardening, which are widely used in applied calculations of structures. A comparative analysis of the theories under complex loading along flat strain trajectories is carried out and covers the entire range of strain paths from multilink polylines to curved trajectories of constant and variable curvatures. The strain path from medium to large curvatures are considered. The analysis of the research results is carried out in the vector space of A.A. Il’yushin. We consider plane trajectories of deformations in the form of a square, three circles passing the origin of coordinates, and trajectories in an asteroid-like form. The results of the calculations are compared with the results of the experimental studies of the response stress trajectories, scalar and vector properties. Variants of theories are considered: isotropic hardening model; Ishlinsky-Prager-Kadashevich-Novozhilov model (linear kinematic and isotropic hardening); model similar to Ono-Wang's model; the Armstrong-Frederick-Kadashevich model (the Korotkikh model is based on this model); the Shabosh model with three evolutionary Armstrong-Frederick-Kadashevich equations; Themis model based on the invariant theory of plasticity; Bondar model with a three-term structure of the evolutionary equation for kinematic hardening. We give the material parameters (functions) that close the variants of plasticity theories. A satisfactory agreement with the experiment for all deformation trajectories is achieved in calculations based on the models of Ishlinsky-Prager-Kadashevich-Novozhilov, Shabosh and Temis. The difference between the results of calculations and experiments does not exceed 30 %. The best agreement with the experiment is achieved on the basis of the Bondar model with the difference between the results of the calculations and experiments for all trajectories less than 10 %.
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Okunev, I., i V. Vinogradov. "Regional Security Complexes (Spatial Autocorrelation and Cluster Analysis Stimulation)". World Economy and International Relations 65, nr 4 (2021): 30–41. http://dx.doi.org/10.20542/0131-2227-2021-65-4-30-41.
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Received 23.03.2020. Security studies are going through a new stage of development. The 20th century was marked by scientific discussions about globalization itself and its possible impact on international security, the need to adjust concepts and methodologies. Many modern challenges are a direct consequence of increased global interdependence. At the same time, global attention is shifting towards regions, because the processes originating there can explain and determine the structure of international security. In turn, it is vital to adopt the knowledge and methodology of regional studies and political geography to avoid the “territorial trap”. In our opinion, international studies are still missing the importance of spatiality and its influence on the world political system. Regardless the importance of geographical factor and the fact that in some way it determines the vector of the world political system development, spatiality is often overlooked. “Thinking in the space” is a skill necessary for any researcher. Spatiality is not just a set of geographical characteristics, but something more integral. Therefore, to understand international security and prospects for its further development, we need a comprehensive approach taking a wide range of factors into account. Moreover, an important problem of modern international security is the lack of comprehensive security studies at the global level that take into account the factor of space and regionalization. The research identifies Regional Security Complexes using cluster analysis of k-means. A spatial autocorrelation analysis is used to justify found systems, which consider the mutual influence of countries on each other. In a nutshell, it can explain regionalization of international security and the role of spatial factor in this process, create methodological framework for further analysis of Regional Security Complexes. Acknowledgements. The article has been supported by the grant of the IIS MGIMO No. 1921-01-09 “Geopolitical Atlas of the Modern World: Cartograms Modelling, Multidimensional Scaling and Determination of Local Indicators of Spatial Autocorrelation in World Politics”.
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du Plessis, Louis, Christo Venter, Zorawar Wadiasingh, Alice K. Harding, David A. H. Buckley, Stephen B. Potter i P. J. Meintjes. "Probing the non-thermal emission geometry of AR Sco via optical phase-resolved polarimetry". Monthly Notices of the Royal Astronomical Society 510, nr 2 (11.12.2021): 2998–3010. http://dx.doi.org/10.1093/mnras/stab3595.
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ABSTRACT AR Sco is a binary system that contains a white and red dwarf. The rotation rate of the white dwarf (WD) has been observed to slow down, analogous to rotation-powered radio pulsars; it has thus been dubbed a ‘white dwarf pulsar’. We previously fit the traditional radio pulsar rotating vector model to the linearly polarized optical data from this source, constraining the system geometry as well as the WD mass. Using a much more extensive data set, we now explore the application of the same model to binary phase-resolved optical polarimetric data, thought to be the result of non-thermal synchrotron radiation, and derive the magnetic inclination angle α and the observer angle ζ at different orbital phases. We obtain an ∼10° variation in α and ∼30° variation in ζ over the orbital period. The variation patterns in these two parameters is robust, regardless of the binning and epoch of data used. We speculate that the observer is detecting radiation from an asymmetric emission region that is a stable structure over several orbital periods. The success of this simple model lastly implies that the pitch angles of the particles are small and the pulsed, non-thermal emission originates relatively close to the WD surface.
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Vollmer, B., C. Pappalardo, M. Soida i A. Lançon. "Two uneven sisters". Astronomy & Astrophysics 620 (grudzień 2018): A108. http://dx.doi.org/10.1051/0004-6361/201731910.
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Since the Virgo cluster is the closest galaxy cluster in the northern hemisphere, galaxy interactions can be observed in it at kiloparsec resolution. The spiral galaxy NGC 4388 underwent a ram-pressure stripping event ∼200 Myr ago caused by its highly eccentric orbit within the Virgo cluster. This galaxy fulfills all diagnostic criteria for having undergone active ram-pressure stripping in the recent past: it has a strongly truncated HI and Hα disk, an asymmetric ridge of polarized radio continuum emission, extended extraplanar gas toward the opposite side of the ridge of polarized radio continuum emission, and has undergone a recent (a few hundred million years ago) quenching of its star formation activity in the outer, gas-free galactic disk. We made dynamical simulations of the ram-pressure stripping event to investigate the influence of galactic structure on the observed properties of NGC 4388. The combination of a deep optical spectrum of the outer gas-free region of the galactic disk together with deep HI, Hα, far-ultraviolet, and polarized radio continuum data allows us to constrain numerical simulations to derive the temporal ram-pressure profile, the three-dimensional velocity vector of the galaxy, and the time since peak ram pressure with a high level of confidence. From the simulations, an angle between the ram-pressure wind and the galactic disk of 30° is derived. The galaxy underwent peak ram pressure ∼240 Myr ago. The observed asymmetries in the disk of NGC 4388 are not caused by the present action of ram pressure, but by the resettling of gas that has been pushed out of the galactic disk during the ram-pressure stripping event. For the detailed reproduction of multi-wavelength observations of a spiral galaxy that undergoes or underwent a ram-pressure stripping event, galactic structure, such as spiral arms for example, must be taken into account.
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Gogoleva, Elena. "Information Policy of Local Authority in Internet as a Factor of Societal Regulation: Sociological Analysis". Logos et Praxis, nr 2 (październik 2022): 81–90. http://dx.doi.org/10.15688/lp.jvolsu.2022.2.9.
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Influence of information on the social management is constantly increasing. Information policy in Russian local self-government system is a given of maintaining significant social relationships in municipality and a factor of the development of civil society. The interactive information policy contributes to the preservation of sensed-presence effect of local community in the public area, and to the setting new goals of the municipal development. Research problem is the lack of actual sociological facts about the abilities and limitations of organization and implementation of local information policy that are adequate to the needs of the local community. The goal of the sociological research is to define and evaluate content and functional characteristics of the local authoritys work on keeping feedback with local community in the space of Internet. The methodological basis of the sociological research is the system approach under which local self-government analyzed as the open system in which interaction between social agents is supported through information. Discourse analysis as a method of qualitative empirical research has made it possible to identify the specifics of information representation by local governments on the Internet in the process of creating and maintaining an information and communication structure of social interaction. On the basis of the data obtained, insufficient information openness, interactivity and usability of the Internet sites of local governments were established, which complicates the development of intergroup ties and relations. The author focuses on the declarative realization of information policy in the sites that focuses on the one-sided vector of information and the dominance of the subject of management. The functionality of the Internet-sites is limited to the execution of ideological and legal functions while the local authorities do not pay the attention to the forming identity of local community members and their involvement in local government. These facts hinder societal regulation in the municipality that shows in unstable interaction in the process of state-public relations.
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CHURIKANOVA, Olena, i Oksana DENYSENKO. "CIRCULAR ECONOMY – THE FUTURE OF SUSTAINABLE DEVELOPMENT". Herald of Khmelnytskyi National University. Economic sciences 312, nr 6(1) (29.12.2022): 202–7. http://dx.doi.org/10.31891/2307-5740-2022-312-6(1)-30.
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The work is devoted to the analysis of the main principles and approaches to the introduction of the circular economy concept at the state level. The article contains both the theoretical foundations of the introduction of the circular economy, the conceptual apparatus and the analysis of practical cases of the successful introduction of the principles in the global space. In addition, the main problems that may stand in the way of the successful implementation of the circular economy at the state level are outlined. The paper considers the main aspects of the introduction of the concept of circular economy at the state and regional levels. The conceptual apparatus of the circular economy is presented and illustrated, the differences and advantages in comparison with the generally accepted system of the linear economy are noted. Also, the structure of the circular economy at the micro, macro, and meso levels is considered in detail in the work, the key aspects of implementation in the spheres of production, consumption, waste management, and development support are noted. Considerable attention was paid in the study to the tools for the introduction of the circular economy both at the state and regional levels and at the level of other subjects of economic activity. The circular economy toolkit proposed for analysis was considered both in terms of the economic effect of its introduction, and from the point of view of the presence of a certain number of problems for each of the tools. The identified problems on the way to successful application of circular economy tools outlined the vector of further research in this direction with the aim of accelerating the transformation processes of the transition from a linear to a circular form of economy.
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Orienti, M., G. Migliori, G. Brunetti, H. Nagai, F. D’Ammando, K.-H. Mack i M. A. Prieto. "Jansky VLA observations of synchrotron emitting optical hotspots of 3C 227 and 3C 445 radio galaxies". Monthly Notices of the Royal Astronomical Society 494, nr 2 (20.03.2020): 2244–53. http://dx.doi.org/10.1093/mnras/staa777.
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ABSTRACT We report results on deep Jansky Very Large Array (VLA) A-configuration observations at 22 GHz of the hotspots of the radio galaxies 3C 227 and 3C 445. Synchrotron emission in the optical on scales up to a few kpc was reported for the four hotspots. Our VLA observations point out the presence of unresolved regions with upper limit to their linear size of about 100 pc. This is the first time that such compact components in hotspots have been detected in a mini-sample, indicating that they are not a peculiar characteristic of a few individual hotspots. The polarization may reach values up to 70 per cent in compact (about 0.1 kpc scale) regions within the hotspot, indicating a highly ordered magnetic field with size up to a hundred parsecs. On larger scales, the average polarization of the hotspot component is about 30–45 per cent, suggesting the presence of a significant random field component, rather than an ordered magnetic field. This is further supported by the displacement between the peaks in polarized intensity and in total intensity images that is observed in all the four hotspots. The electric vector position angle is not constant, but changes arbitrarily in the central part of the hotspot regions, whereas it is usually perpendicular to the total intensity contours of the outermost edge of the hotspot structure, likely marking the large-scale shock front. The misalignment between X-ray and radio-to-optical emission suggests that the former is tracing the current particle acceleration, whereas the latter marks older shock fronts.
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Pötzl, F. M., A. P. Lobanov, E. Ros, J. L. Gómez, G. Bruni, U. Bach, A. Fuentes i in. "Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron". Astronomy & Astrophysics 648 (kwiecień 2021): A82. http://dx.doi.org/10.1051/0004-6361/202039493.
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Context. Supermassive black holes in the centres of radio-loud active galactic nuclei (AGN) can produce collimated relativistic outflows (jets). Magnetic fields are thought to play a key role in the formation and collimation of these jets, but the details are much debated. Aims. We study the innermost jet morphology and magnetic field strength in the AGN 3C 345 with an unprecedented resolution using images obtained within the framework of the key science programme on AGN polarisation of the Space VLBI mission RadioAstron. Methods. We observed the flat spectrum radio quasar 3C 345 at 1.6 GHz on 2016 March 30 with RadioAstron and 18 ground-based radio telescopes in full polarisation mode. Results. Our images, in both total intensity and linear polarisation, reveal a complex jet structure at 300 μas angular resolution, corresponding to a projected linear scale of about 2 pc or a few thousand gravitational radii. We identify the synchrotron self-absorbed core at the jet base and find the brightest feature in the jet 1.5 mas downstream of the core. Several polarised components appear in the Space VLBI images that cannot be seen from ground array-only images. Except for the core, the electric vector position angles follow the local jet direction, suggesting a magnetic field perpendicular to the jet. This indicates the presence of plane perpendicular shocks in these regions. Additionally, we infer a minimum brightness temperature at the largest (u, v)-distances of 1.1 × 1012 K in the source frame, which is above the inverse Compton limit and an order of magnitude larger than the equipartition value. This indicates locally efficient injection or re-acceleration of particles in the jet to counter the inverse Compton cooling or the geometry of the jet creates significant changes in the Doppler factor, which has to be > 11 to explain the high brightness temperatures.
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Marton, G., P. Ábrahám, E. Szegedi-Elek, J. Varga, M. Kun, Á. Kóspál, E. Varga-Verebélyi i in. "Identification of Young Stellar Object candidates in the Gaia DR2 x AllWISE catalogue with machine learning methods". Monthly Notices of the Royal Astronomical Society 487, nr 2 (14.05.2019): 2522–37. http://dx.doi.org/10.1093/mnras/stz1301.
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ABSTRACT The second Gaia Data Release (DR2) contains astrometric and photometric data for more than 1.6 billion objects with mean Gaia G magnitude <20.7, including many Young Stellar Objects (YSOs) in different evolutionary stages. In order to explore the YSO population of the Milky Way, we combined the Gaia DR2 data base with Wide-field Infrared Survey Explorer (WISE) and Planck measurements and made an all-sky probabilistic catalogue of YSOs using machine learning techniques, such as Support Vector Machines, Random Forests, or Neural Networks. Our input catalogue contains 103 million objects from the DR2xAllWISE cross-match table. We classified each object into four main classes: YSOs, extragalactic objects, main-sequence stars, and evolved stars. At a 90 per cent probability threshold, we identified 1 129 295 YSO candidates. To demonstrate the quality and potential of our YSO catalogue, here we present two applications of it. (1) We explore the 3D structure of the Orion A star-forming complex and show that the spatial distribution of the YSOs classified by our procedure is in agreement with recent results from the literature. (2) We use our catalogue to classify published Gaia Science Alerts. As Gaia measures the sources at multiple epochs, it can efficiently discover transient events, including sudden brightness changes of YSOs caused by dynamic processes of their circumstellar disc. However, in many cases the physical nature of the published alert sources are not known. A cross-check with our new catalogue shows that about 30 per cent more of the published Gaia alerts can most likely be attributed to YSO activity. The catalogue can be also useful to identify YSOs among future Gaia alerts.
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Zou, Yajie, Xuedong Hua, Yanru Zhang i Yinhai Wang. "Hybrid short-term freeway speed prediction methods based on periodic analysis". Canadian Journal of Civil Engineering 42, nr 8 (sierpień 2015): 570–82. http://dx.doi.org/10.1139/cjce-2014-0447.
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Short-term traffic speed forecasting is an important issue for developing Intelligent Transportation Systems applications. So far, a number of short-term speed prediction approaches have been developed. Recently, some multivariate approaches have been proposed to consider the spatial and temporal correlation of traffic data. However, as traffic data often demonstrates periodic patterns, the existing methodologies often fail to take into account spatial and temporal information as well as the periodic features of traffic data simultaneously in the multi-step prediction. This paper comprehensively evaluated the multi-step prediction performance of space time (ST) model, vector autoregression (VAR), and autoregressive integrated moving average (ARIMA) models using the 5 minute freeway speed data collected from five loop detectors located on an eastbound segment of Interstate 394 freeway, in Minnesota. To further consider the cyclical characteristics of freeway speed data, hybrid prediction approaches were proposed to decompose speed into two different components: a periodic trend and a residual part. A trigonometric regression function is introduced to capture the periodic component and the residual part is modeled by the ST, VAR, and ARIMA models. The prediction results suggest that for multi-step freeway speed prediction, as the time step increases, the ST model demonstrates advantages over the VAR and ARIMA models. Comparisons among the ST, VAR, ARIMA, and hybrid models demonstrated that modeling the periodicity and the residual part separately can better interpret the underlining structure of the speed data. The proposed hybrid prediction approach can accommodate the periodic trends and provide more accurate prediction results when the forecasting horizon is greater than 30 min.
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Chandrasenan, Archa, i Joseph Zacharias. "Non-linear photonic loop mirror based co-site interference canceller". Laser Physics Letters 19, nr 11 (13.10.2022): 116207. http://dx.doi.org/10.1088/1612-202x/ac9679.
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Abstract Full duplex-in band (FDIB) is a well-established solution for increasing the data rate and spreading the link range for future communication systems. FDIB systems need no additional bandwidth requirement. However, they are confronted with a major interference challenge on the same site, called co-site interference (CSI). Long-established co-site interference cancellation (CSIC) methods achieve a cancellation depth upto 35 dB, conversely it has space containments, manufacturing imperfections, induces noise penalties and limits isolation bandwidth. To overcome these problems, RF photonic CSIC methods have been developed, which have produced 30 dB wide-band interference suppression. They also increase bandwidth, have a flexible structure, minimize losses and prevent periodic power fading. But these systems have a problem of inherent DC drift, low maintenance of coherence, and low isolation at low transmission power. Thus, there is a high need for photonic CSIC designs of FDIB systems that operate over wider bandwidths and at higher transmission powers. Here, a newfangled CSIC system based on a non-linear photonic loop and frequency down-conversion is proposed. It shows excellent CSIC suppression of greater than 61 dB, for a single frequency signal of interest (SOI) with maximum RF power of 13 dBm. Without frequency down-conversion, the system maintains an average cancellation depth of 62.541 dB for single frequency SOI. After frequency down conversion, the system maintains an average cancellation depth of 61.208 dB for narrow band SOI. The system attains 18% error vector magnitude at −20 dB RF output power, which confirms the comprehensive quality of the system.
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Poveschenko, Yuri Andreevich, Alexander Yur’evich Krukovskiy, Dmitri Sergeevich Boykov, Victoria Olegovna Podryga i Parvin Ilgar gizi Rahimly. "Three-dimensional modeling of hydrodynamic problems taking into account elastic processes". Keldysh Institute Preprints, nr 30 (2021): 1–15. http://dx.doi.org/10.20948/prepr-2021-30.
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A finite-difference approximation of elastic forces on spaced Lagrangian grids is constructed, based on the method of support operators. For displacement vectors on irregular grids, on the topological and geometric structure of which minimal reasonable restrictions are imposed, the approximations of vector analysis operations are constructed in relation to difference schemes for problems of elasticity theory. Taking into account the energy balance of the medium, the constructed families of integrally consistent approximations of vector analysis operations are sufficient for discrete modeling of these processes. The schemes are considered, both using the stress tensor in an explicit form, and dividing it into spherical and shear components (pressure and deviator). The latter is used to construct homogeneous algorithms applicable to both the solid and the vaporized phase. The linear theory of elasticity is used for constructing approximations. The resulting forces in spatial geometry are obtained explicitly. Calculations of the sound waves propagation in a three-dimensional orthogonal aluminum plate due to end impact are presented. These calculations confirm the good quality of the difference schemes constructed in work.
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Kuo, F. S., H. Y. Lue, C. L. Fern, J. Röttger, S. Fukao i M. Yamamoto. "Statistical characteristics of AGW wave packet propagation in the lower atmosphere observed by the MU radar". Annales Geophysicae 27, nr 10 (2.10.2009): 3737–53. http://dx.doi.org/10.5194/angeo-27-3737-2009.
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Abstract. We study the horizontal structure of the atmospheric gravity waves (AGW) in the height ranges between 6 and 22 km observed using the MU radar at Shigaraki in Japan, during a 3 day period in January and a 4 day period in August 1988. The data were divided by double Fourier transformation into a data set of upward moving waves and a data set of downward moving waves for independent analysis. The phase and group velocity tracing technique was applied to measure the vertical group and phase velocity as well as the characteristic period of the gravity wave packet. Then the dispersion equation of the linear theory of AGW was solved to obtain its intrinsic wave period – horizontal wavelength and horizontal group velocity – and the vertical flux of horizontal momentum associated with each wave packet was estimated to help determine the direction of the characteristic horizontal wave vector. The results showed that the waves with periods in the range of 30 min~6 h had horizontal scales ranging from 20 km to 1500 km, vertical scales from 4 km to 15 km, and horizontal phase velocities from 15 m/s to 60 m/s. The upward moving wave packets of wave period of 2 h~6 h had horizontal group velocities mainly toward east-south-east and northeast in winter, and mainly in the section between the directions of west-north-west and north in summer.
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Nicholls, Stephen D., i George S. Young. "Dendritic Patterns in Tropical Cumulus: An Observational Analysis". Monthly Weather Review 135, nr 5 (1.05.2007): 1994–2005. http://dx.doi.org/10.1175/mwr3379.1.
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Abstract An observational analysis of the structure and synoptic setting of tropical dendritic cumulus formations was undertaken using 30 months of global data from the Moderate Resolution Imaging Spectroradiometer aboard the National Aeronautics and Space Administration Terra satellite, the Quick Scatterometer aboard the SeaWinds satellite, and the National Centers for Environmental Prediction global reanalysis. This analysis yielded 1216 cases of tropical dendritic cumulus formations of which 61 were randomly selected for quantitative study. From these sample cases, it was found that dendritic patterns in shallow cumulus occurred over warm tropical oceans in response to cold air advection. They typically dissipate downstream in regions of cooler water, neutral to warm advection, or deep convection. Moreover, shallow cumulus formations take on a dendritic pattern only in areas where the background wind velocity is between 1.5 and 13 m s−1 in the surface to the 850-mb layer and a shallow layer of conditional instability is present. Individual cumulus clouds in these dendritic formations are arranged in a compound, hierarchical branching pattern in which each element of the pattern takes the form of a Y-shaped cloud line. Analysis of the cloud pattern observations in conjunction with the scatterometer-derived surface winds and the lower-tropospheric wind profiles from reanalysis data reveals that the individual Y elements are aligned closely with the surface wind direction, as linear cloud streets would be. These Y elements are oriented so that their forked end aligns as closely as possible with the surface-to-850-mb shear vector, even when this conflicts with the surface wind direction. A formation mechanism is hypothesized by which the secondary circulation of a towering cumulus line modifies the shear and stability profiles in the adjacent areas to favor shallower cumulus lines oriented at an angle to itself, thus forming a hierarchical branching structure. This hypothesis is supported by stability profiles from the reanalysis data.
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Agapitov, O., V. Krasnoselskikh, Yu Zaliznyak, V. Angelopoulos, O. Le Contel i G. Rolland. "Observations and modeling of forward and reflected chorus waves captured by THEMIS". Annales Geophysicae 29, nr 3 (11.03.2011): 541–50. http://dx.doi.org/10.5194/angeo-29-541-2011.
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Abstract. Discrete ELF/VLF chorus emissions are the most intense electromagnetic plasma waves observed in the radiation belts of the Earth's magnetosphere. Chorus emissions, whistler-mode wave packets propagating roughly along magnetic field lines from a well-localized source in the vicinity of the magnetic equator to polar regions, can be reflected at low altitudes. After reflection, wave packets can return to the equatorial plane region. Understanding of whistler wave propagation and reflection is critical to a correct description of wave-particle interaction in the radiation belts. We focus on properties of reflected chorus emissions observed by the THEMIS (Time History of Events and Macroscale Interactions During Substorms) spacecraft Search Coil Magnetometer (SCM) and Electric Field Instrument (EFI) at ELF/VLF frequencies up to 4 kHz at L≥8. We determine the direction of the Poynting flux and wave vector distribution for forward and reflected chorus waves. Although both types of chorus waves were detected near the magnetic equator and have similar, discrete structure and rising tones, reflected waves are attenuated by a factor of 10–30 and have 10% higher frequency than concurrently-observed forward waves. Modeling of wave propagation and reflection using geometrical optics ray-tracing allowed us to determine the chorus source region location and explain observed propagation characteristics. We find that reflected wave attenuation at a certain spatial region is caused by divergence of the ray paths of these non-ducted emissions, and that the frequency shift is caused by generation of the reflected waves at lower L-shells where the local equatorial gyrofrequency is larger.
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Akhmedov, Yunus, Shuhrat Asadov i Bobir Azimov. "Two-sided estimation of linear approximation error second - order hypersurfaces". Journal of Physics: Conference Series 2388, nr 1 (1.12.2022): 012124. http://dx.doi.org/10.1088/1742-6596/2388/1/012124.
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Abstract The following aspects of multidimensional space are considered in the article. The parametrizations of the hypersurface of the second order are considered, which allow visualizing them in the process of discretization. The development of the principle of vector modeling for displaying objects of multidimensional space on a two-dimensional plane made it possible to visually display the solution to the problem of linear approximation of a second-order hypersurface. The proposed method for discretizing a second-order hypersurface makes it possible to create a simple algorithm for its linear ash-approximation, which is the basis for solving the linear programming problem in automatic mode. The developed method of two-sided estimation of the error in the case of linear approximation of the second-order hypersurface allows us to present the problem of determining the bearing capacity of structures as a linear programming problem.
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R, Rakesh, Mriganka Ghosh Majumder, K. Gopakumar, Loganathan Umanand, Carlo Cecati i Dariusz Zielinski. "A Dense Multilevel 30-Sided Space Vector Generation Using a Single DC Link for an Induction Motor Drive". IEEE Transactions on Power Electronics 36, nr 10 (październik 2021): 11681–90. http://dx.doi.org/10.1109/tpel.2021.3070078.
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Frolova, E. V., T. M. Ryabova, O. V. Rogach i N. V. Medvedeva. "State Educational Order as a Factor in the Socio-Economic Development of Regions". Education and science journal 22, nr 1 (5.02.2020): 9–30. http://dx.doi.org/10.17853/1994-5639-2020-1-9-30.
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Introduction. Successful solution of the tasks of socio-economic development in the modern world is possible only in the case of effective functioning of the education system, which would provide training for a competitive personality, focused on continuous development and capable of “complying” with rapidly changing conditions of social reality. It is assumed that building an education development strategy, setting its goals and objectives should be based on the needs and problems of society, creating the basis for sustainable prosperity of the country and taking into account the needs of individual regions and territories. One of the most important mechanisms for the development of the regions of the Russian Federation remained the state educational order – officially developed task by the authorities for the creation of a specific educational product.The aims of the present article are the following: to determine the relationship between the educational state order, the volume of investments in the education system and the level of socio-economic condition of the regions; to identify the territories, which require support.Methodology and research methods. In the course of the study, the methods of comparative, statistical and system analysis, deduction and induction, generalisation and theoretical modelling were used. The object of the content analysis was the regional programmes for the development of education in 40 regions of the Russian Federation, covering the entire territory of Russia and reflecting the specific development of various regions depending on the remoteness of the capital, the status of the subject of the Russian Federation and the socio-economic development of the region.Results and scientific novelty. Russian regions were classified into four groups according to the results of the analysis of regional educational development – very high, high, moderate and low. A number of general and specific problems of education in the regions were identified: the lack of a single educational space and, as a result, the heterogeneity of educational programmes; regional leaders disregard for opportunities to expand socio-economic potential of the territories through the implementation of such programmes; the gap between the financing of education and its socio-economic importance, etc. The authors conclude that state educational order at the regional level is not considered as a vector of social and economic development of the territories, and its role is reduced to an educati onal level. It is established that the rate of development of education in the Russian regions does not always depend on their key socio-economic indicators. The greatest differentiation of the trend is recorded, when comparing the rate of development of the regional education systems and the gross regional product.Practical significance. The authors give recommendations to resolve disagreements over the formation of state education orders in the context of the socioeconomic development of regions. The need to develop regional economic development programmes, taking into account the specific social structure of the region, is emphasised. It is proposed to organise permanent social monitoring, which measures the quality of implementation of educational state order and strengthen the role of public participation when determining its content. The research materials and findings might be used by the executive authorities of the constituent entities of the Russian Federation, whose competence includes educational development issues.
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Launhardt, R., Th Henning, A. Quirrenbach, D. Ségransan, H. Avenhaus, R. van Boekel, S. S. Brems i in. "ISPY-NACO Imaging Survey for Planets around Young stars". Astronomy & Astrophysics 635 (marzec 2020): A162. http://dx.doi.org/10.1051/0004-6361/201937000.
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Context. The occurrence rate of long-period (a ≳ 50 au) giant planets around young stars is highly uncertain since it is not only governed by the protoplanetary disc structure and planet formation process, but also reflects both dynamical re-structuring processes after planet formation as well as possible capture of planets not formed in situ. Direct imaging is currently the only feasible method to detect such wide-orbit planets and constrain their occurrence rate. Aims. We aim to detect and characterise wide-orbit giant planets during and shortly after their formation phase within protoplanetary and debris discs around nearby young stars. Methods. We carry out a large L′-band high-contrast direct imaging survey for giant planets around 200 young stars with protoplanetary or debris discs using the NACO instrument at the ESO Very Large Telescope on Cerro Paranal in Chile. We use very deep angular differential imaging observations with typically >60° field rotation, and employ a vector vortex coronagraph where feasible to achieve the best possible point source sensitivity down to an inner working angle of about 100 mas. This paper introduces the NACO Imaging Survey for Planets around Young stars (NACO-ISPY), its goals and strategy, the target list, and data reduction scheme, and presents preliminary results from the first 2.5 survey years. Results. We achieve a mean 5 σ contrast of ΔL′ = 6.4 ± 0.1 mag at 150 mas and a background limit of L′bg = 16.5±0.2 mag at >1.′′5. Our detection probability is >50% for companions with ≳8 MJup at semi-major axes of 80–200 au and >13 MJup at 30–250 au. It thus compares well to the detection space of other state-of-the-art high-contrast imaging surveys. We have already contributed to the characterisation of two new planets originally discovered by VLT/SPHERE, but we have not yet independently discovered new planets around any of our target stars. We have discovered two new close-in low-mass stellar companions around R CrA and HD 193571 and report in this paper the discovery of close co-moving low-mass stellar companions around HD 72660 and HD 92536. Furthermore, we report L′-band scattered light images of the discs around eleven stars, six of which have never been imaged at L′-band before. Conclusions. The first 2.5 yr of the NACO-ISPY survey have already demonstrated that VLT/NACO combined with our survey strategy can achieve the anticipated sensitivity to detect giant planets and reveal new close stellar companions around our target stars.
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Förster, M., S. E. Haaland, G. Paschmann, J. M. Quinn, R. B. Torbert, H. Vaith i C. A. Kletzing. "High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements". Annales Geophysicae 26, nr 9 (12.09.2008): 2685–700. http://dx.doi.org/10.5194/angeo-26-2685-2008.
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Abstract. In this study, we investigate statistical, systematic variations of the high-latitude convection cell structure during northward IMF. Using 1-min-averages of Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for six and a half years (February 2001 till July 2007), and mapping the spatially distributed measurements to a common reference plane at ionospheric level in a magnetic latitude/MLT grid, we obtained regular drift patterns according to the various IMF conditions. We focus on the particular conditions during northward IMF, where lobe cells at magnetic latitudes >80° with opposite (sunward) convection over the central polar cap are a permanent feature in addition to the main convection cells at lower latitudes. They are due to reconnection processes at the magnetopause boundary poleward of the cusp regions. Mapped EDI data have a particular good coverage within the central part of the polar cap, so that these patterns and their dependence on various solar wind conditions are well verified in a statistical sense. On average, 4-cell convection pattern are shown as regular structures during periods of nearly northward IMF with the tendency of a small shift toward negative clock angles. The positions of these high-latitude convection foci are within 79° to 85° magnetic latitude and 09:00–15:00 MLT. The MLT positions are approximately symmetric ±2 h about 11:30 MLT, i.e. slightly offset from midday toward prenoon hours, while the maximum (minimum) potential of the high-latitude cells is at higher magnetic latitudes near their maximum potential difference at ≈−10° to −15° clock angle for the North (South) Hemisphere. With increasing clock angle distances from ≈IMFBz+, a gradual transition occurs from the 4-cell pattern via a 3-cell to the common 2-cell convection pattern, in the course of which one of the medium-scale high-latitude dayside cells diminishes and disappears while the other intensifies and merges with the opposite main cell of the same polarity to form the large "round-shaped" convection cell when approaching a well-known IMFBy-dominated configuration. Opposite scenarios with interchanged roles of the respective cells occur for the opposite turning of the clock angle and at the Southern Hemisphere. The high-latitude dayside cells become more pronounced with increasing magnitude of the IMF vector.
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Haaland, S., B. Sonnerup i G. Paschmann. "More about arc-polarized structures in the solar wind". Annales Geophysicae 30, nr 5 (25.05.2012): 867–83. http://dx.doi.org/10.5194/angeo-30-867-2012.
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Abstract. We report results from a Cluster-based study of the properties of 28 arc-polarized magnetic structures (also called rotational discontinuities) in the solar wind. These Alfvénic events were selected from the database created and analyzed by Knetter (2005) by use of criteria chosen to eliminate ambiguous cases. His studies showed that standard, four-spacecraft timing analysis in most cases lacks sufficient accuracy to identify the small normal magnetic field components expected to accompany such structures, leaving unanswered the question of their existence. Our study aims to break this impasse. By careful application of minimum variance analysis of the magnetic field (MVAB) from each individual spacecraft, we show that, in most cases, a small but significantly non-zero magnetic field component was present in the direction perpendicular to the discontinuity. In the very few cases where this component was found to be large, examination revealed that MVAB had produced an unusual and unexplained orientation of the normal vector. On the whole, MVAB shows that many verifiable rotational discontinuities (Bn ≠ 0) exist in the solar wind and that their eigenvalue ratio (EVR = intermediate/minimum variance) can be extremely large (up to EVR = 400). Each of our events comprises four individual spacecraft crossings. The events include 17 ion-polarized cases and 11 electron-polarized ones. Fifteen of the ion events have widths ranging from 9 to 21 ion inertial lengths, with two outliers at 46 and 54. The electron-polarized events are generally thicker: nine cases fall in the range 20–71 ion inertial lengths, with two outliers at 9 and 13. In agreement with theoretical predictions from a one-dimensional, ideal, Hall-MHD description (Sonnerup et al., 2010), the ion-polarized events show a small depression in field magnitude, while the electron-polarized ones tend to show a small enhancement. This effect was also predicted by Wu and Lee (2000). Judging only from the sense of the plasma flow across our DDs, their propagation appears to be sunward as often as anti-sunward. However, we argue that this result can be misleading as a consequence of the possible presence of magnetic islands within the DDs. How the rotational discontinuities come into existence, how they evolve with time, and what roles they play in the solar wind remain open questions.
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Line, C. M. B., M. T. Dove, K. S. Knight i B. Winkler. "The low-temperature behaviour of analcime. 1: high-resolution neutron powder diffraction". Mineralogical Magazine 60, nr 400 (czerwiec 1996): 499–507. http://dx.doi.org/10.1180/minmag.1996.060.400.11.
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AbstractThe structure of a synthetic sample of analcime has been determined as a function of temperature between 30–300 K by high-resolution neutron powder diffraction. Although there are some reports of samples of analcime having non-cubic structures, the sample in our experiments remained cubic (space group la3d), and hence disordered, down to low temperatures. The absence of phase transitions involving ordering of the orientations of the water molecules, ordering of the sodium positions, or a displacive instability as in leucite and related materials, is discussed. We speculate that part of the reason for the absence of ordering of the water molecules or sodium cations is associated with the Al/Si disorder, which cannot order at low temperatures. We also discuss the likely distribution of the orientations of the water molecules at low temperatures, and propose that the water diads lie close to any of the crystal diads with the H-H Vectors lying close to the triads.
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Gay, Jeffrey P., Lowell Miyagi, Samantha Couper, Christopher Langrand, David P. Dobson, Hanns-Peter Liermann i Sébastien Merkel. "Deformation of NaCoF<sub>3</sub> perovskite and post-perovskite up to 30 GPa and 1013 K: implications for plastic deformation and transformation mechanism". European Journal of Mineralogy 33, nr 5 (30.09.2021): 591–603. http://dx.doi.org/10.5194/ejm-33-591-2021.
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Abstract. Texture, plastic deformation, and phase transformation mechanisms in perovskite and post-perovskite are of general interest for our understanding of the Earth's mantle. Here, the perovskite analogue NaCoF3 is deformed in a resistive-heated diamond anvil cell (DAC) up to 30 GPa and 1013 K. The in situ state of the sample, including crystal structure, stress, and texture, is monitored using X-ray diffraction. A phase transformation from a perovskite to a post-perovskite structure is observed between 20.1 and 26.1 GPa. Normalized stress drops by a factor of 3 during transformation as a result of transient weakening during the transformation. The perovskite phase initially develops a texture with a maximum at 100 and a strong 010 minimum in the inverse pole figure of the compression direction. Additionally, a secondary weaker 001 maximum is observed later during compression. Texture simulations indicate that the initial deformation of perovskite requires slip along (100) planes with significant contributions of {110} twins. Following the phase transition to post-perovskite, we observe a 010 maximum, which later evolves with compression. The transformation follows orientation relationships previously suggested where the c axis is preserved between phases and hh0 vectors in reciprocal space of post-perovskite are parallel to [010] in perovskite, which indicates a martensitic-like transition mechanism. A comparison between past experiments on bridgmanite and current results indicates that NaCoF3 is a good analogue to understand the development of microstructures within the Earth's mantle.
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Vermennikova, L. V., A. N. Lupishko i D. V. Veselova. "SYNERGY OF LEAN TECHNOLOGIES AND DIGITALIZATION IN THE CONTEXT OF INCREASING THE EFFECTIVENESS OF PROCESSES IN AN EDUCATIONAL INSTITUTION". Bulletin of Udmurt University. Series Economics and Law 30, nr 3 (26.06.2020): 325–52. http://dx.doi.org/10.35634/2412-9593-2020-30-3-325-332.
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Digitalization of universities is an actual trend of our time, due to the direction of development of the Russian economy, focused on improving its efficiency. The tools for achieving this goal are largely lean and digital technologies.The existing regulatory framework of the Russian Federation in the field of effective development is analyzed. The object of analysis is federal and national projects and programs, the purpose of which is to increase labor productivity, ensure the quality and accessibility of services in various fields. The existence of links between federal projects aimed at improving the efficiency of various sectors of the economy through the introduction of lean manufacturing and projects aimed at creating a digital space is demonstrated. The necessity of conforming the development path of educational structures to the vectors of modern social development is substantiated in terms of transferring their internal processes to a qualitatively new level using lean technologies and digitalization of processes. The experience of implementing projects for improvements using lean technologies and digitalization at the Kuban State Medical University is described. The analysis of the effectiveness of projects implemented in the framework of the concept of "Lean university", with the use of digitalization and without its use. Conclusions are drawn about the limitations of the use of digitalization to improve the efficiency of processes, the risks of its use in educational institutions, as well as the need for the synthesis of lean technologies and digitalization in the context of the effective development of organizations.
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Khoroshavin, V. S., i V. S. Grudinin. "Optimal programmed movement with variable control times". Radio industry (Russia) 30, nr 3 (8.09.2020): 40–49. http://dx.doi.org/10.21778/2413-9599-2020-30-3-40-49.
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The problems of speed and accuracy are typical in the theory and practice of optimal control, and the requirement for the technology of minimum deviation from a given motion is often more important than speed. The search for controls that ensure the accuracy of reproducing the trajectory of motion for a given time of the transient process is considered. The Pontryagin maximum principle is used as the main method. It is supplemented for the study of special situations without analyzing auxiliary variables by the state commonness conditions (SCC) for nonlinear systems in extended coordinate space, taking into account an object, a criterion nonlinear in coordinate deviations, and an explicit occurrence of time. To expand the control algorithms, the elements of the vectors that affect the execution of the SCC are investigated. The transition time is determined by the parameter introduced into the integral criterion of accuracy, which characterizes the rate of change of coordinates. An example of a transition to the origin of coordinates of an object with two series-connected integrators with a criterion that takes into account the accuracy and time of the transition is considered. With the help of SCC, new control algorithms and structures of closed systems are obtained. Relationships between the regulation time parameter and the initial conditions for coordinates are determined. Taking into account the constraint on the control, the conditions for realizing the continuous special control and / or sliding mode are obtained. Analytical materials are confirmed by the results of system modeling. The results of the work can be used for control, including nonlinear objects, in robotics, thermal processes (furnaces, autoclaves, intermittent heating control in buildings).
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Sheu, Albert Jeu-Liang. "A Cancellation Theorem for Modules Over the Group C*-Algebras of Certain Nilpotent Lie Groups". Canadian Journal of Mathematics 39, nr 2 (1.04.1987): 365–427. http://dx.doi.org/10.4153/cjm-1987-018-7.
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In recent years, there has been a rapid growth of the K-theory of C*-algebras. From a certain point of view, C*-algebras can be treated as “non-commutative topological spaces”, while finitely generated projective modules over them can be thought of as “non-commutative vector bundles”. The K-theory of C*-algebras [30] then generalizes the classical K-theory of topological spaces [1]. In particular, the K0-group of a unital C*-algebra A is the group “generated” by (or more precisely, the Grothendieck group of) the commutative semigroup of stable isomorphism classes of finitely generated projective modules over A with direct summation as the binary operation. The semigroup gives an order structure on K0(A) and is usually called the positive cone in K0(A).Around 1980, the work of Pimsner and Voiculescu [18] and of A. Connes [4] provided effective ways to compute the K-groups of C*-algebras. Then the classification of finitely generated projective modules over certain unital C*-algebras up to stable isomorphism could be done by computing their K0-groups as ordered groups. Later on, inspired by A. Connes's development of non-commutative differential geometry on finitely generated projective modules [2], the deeper question of classifying such modules up to isomorphism and hence the so-called cancellation question were raised (cf. [21] ).
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Ferreira, F. A., W. J. B. Corradi, F. F. S. Maia, M. S. Angelo i J. F. C. Santos. "Discovery and astrophysical properties of Galactic open clusters in dense stellar fields using Gaia DR2". Monthly Notices of the Royal Astronomical Society 496, nr 2 (15.06.2020): 2021–38. http://dx.doi.org/10.1093/mnras/staa1684.
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ABSTRACT We report the discovery of 25 new open clusters resulting from a search in dense low Galactic latitude fields. We also provide, for the first time, structural and astrophysical parameters for the new findings and 34 other recently discovered open clusters using Gaia Data Release 2 (DR2) data. The candidates were confirmed by jointly inspecting the vector point diagrams and spatial distribution. The discoveries were validated by matching near known objects and comparing their mean astrometric parameters with the available literature. A decontamination algorithm was applied to the three-dimensional astrometric space to derive membership likelihoods for clusters stars. By rejecting stars with low membership likelihoods, we built decontaminated colour–magnitude diagrams and derived the clusters astrophysical parameters by isochrone fitting. The structural parameters were also derived by King-profile fittings over the stellar distributions. The investigated clusters are mainly located within 3 kpc from the Sun, with ages ranging from 30 Myr to 3.2 Gyr and reddening limited to E(B − V) = 2.5. On average, our cluster sample presents less concentrated structures than Gaia DR2 confirmed clusters, since the derived core radii are larger while the tidal radii are not significantly different. Most of them are located in the IV quadrant of the Galactic disc at low latitudes, therefore, they are immersed in dense fields characteristic of the inner Milky Way.
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Bondar, V. S., D. R. Abashev i D. Ju Fomin. "Theories of plasticity under complex loading along spatial trajectories of deformations". PNRPU Mechanics Bulletin, nr 4 (15.12.2021): 41–48. http://dx.doi.org/10.15593/perm.mech/2021.4.05.
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Variants of theories of plastic flow with combined hardening, which are widely used in practical calculations of structures, are considered. A comparative analysis of variants of the theory under complex loading along the spatial trajectories of deformations of constant and variable curvature and torsion is carried out. The trajectories of large curvature and from medium to large torsion are considered. The analysis of the research results is carried out in the vector space of A.A. Il’yushin. The spatial trajectories of deformations in the form of helical lines of constant and variable curvature are considered. The calculation results are compared with the results of experimental studies on the response components of the stress vector and scalar properties along the deformation trajectory. Variants of the theory are considered: the Ishlinsky - Prager - Kadashevich - Novozhilov model (linear kinematic hardening and isotropic hardening); the Shabosh model with three evolutionary Armstrong - Frederick - Kadashevich equations; Themis model based on the invariant theory of plasticity; Bondar model with a three-term transformation of the evolutionary equation for kinematic hardening. Material parameters (functions) that close versions of the theory of plasticity are given. Satisfactory agreement with the experiment for all trajectories of deformations is achived when calculating on the basis of the Shabosh model - the difference between the results of calculations and experiments does not exceed 30 %. The best agreement with the experiment is achieved on the basis of the Bondar model - the difference between the results of calculations and experiments for all trajectories does not exceed 10 %. The Bondar Model is closed by three material parameters and one material function which are determined from simple experiments on uniaxial tension after preliminary compression (kink of the deformation trajectory by 180°). Bondar plasticity model has a generalization for non-isothermal loading, many features of cyclic disproportionate and proportional loading and describes the processes of damage accumulation (resource).
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Campbell, R. J., M. Mathioudakis, M. Collados, P. H. Keys, A. Asensio Ramos, C. J. Nelson, D. Kuridze i A. Reid. "Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere". Astronomy & Astrophysics 647 (marzec 2021): A182. http://dx.doi.org/10.1051/0004-6361/202040028.
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Context. While the longitudinal field that dominates in photospheric network regions has been studied extensively, small-scale transverse fields have recently been found to be ubiquitous in the quiet internetwork photosphere and this merits further study. Furthermore, few observations have been able to capture how this field evolves. Aims. We aim to statistically characterize the magnetic vector in a quiet Sun internetwork region and observe the temporal evolution of specific small-scale magnetic features. Methods. We present two high spatio-temporal resolution observations that reveal the dynamics of two disk-centre internetwork regions taken by the new GREGOR Infrared Spectrograph Integral Field Unit with the highly magnetically sensitive photospheric Fe I line pair at 15648.52 Å and 15652.87 Å. We record the full Stokes vector and apply inversions with the Stokes inversions based on response functions code to retrieve the parameters characterizing the atmosphere. We consider two inversion schemes: scheme 1 (S1), where a magnetic atmosphere is embedded in a field free medium, and scheme 2 (S2), with two magnetic models and a fixed 30% stray light component. Results. The magnetic properties produced from S1 inversions returned a median magnetic field strength of 200 and 240 G for the two datasets, respectively. We consider the median transverse (horizontal) component, among pixels with Stokes Q or U, and the median unsigned longitudinal (vertical) component, among pixels with Stokes V, above a noise threshold. We determined the former to be 263 G and 267 G, and the latter to be 131 G and 145 G, for the two datasets, respectively. Finally, we present three regions of interest, tracking the dynamics of small-scale magnetic features. We apply S1 and S2 inversions to specific profiles of interest and find that the latter produces better approximations when there is evidence of mixed polarities. We find patches of linear polarization with magnetic flux density of the order of 130−150 G and find that linear polarization appears preferentially at granule-intergranular lane boundaries. The weak magnetic field appears to be organized in terms of complex ‘loop-like’ structures, with transverse fields often flanked by opposite polarity longitudinal fields.
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Vlemmings, W. H. T., B. Lankhaar, P. Cazzoletti, C. Ceccobello, D. Dall’Olio, E. F. van Dishoeck, S. Facchini i in. "Stringent limits on the magnetic field strength in the disc of TW Hya". Astronomy & Astrophysics 624 (kwiecień 2019): L7. http://dx.doi.org/10.1051/0004-6361/201935459.
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Despite their importance in the star formation process, measurements of magnetic field strength in proto-planetary discs remain rare. While linear polarisation of dust and molecular lines can give insight into the magnetic field structure, only observations of the circular polarisation produced by Zeeman splitting provide a direct measurement of magnetic field strenghts. One of the most promising probes of magnetic field strengths is the paramagnetic radical CN. Here we present the first Atacama Large Millimeter/submillimeter Array (ALMA) observations of the Zeeman splitting of CN in the disc of TW Hya. The observations indicate an excellent polarisation performance of ALMA, but fail to detect significant polarisation. An analysis of eight individual CN hyperfine components as well as a stacking analysis of the strongest (non-blended) hyperfine components yields the most stringent limits obtained so far on the magnetic field strength in a proto-planetary disc. We find that the vertical component of the magnetic field |Bz| < 0.8 mG (1σ limit). We also provide a 1σ toroidal field strength limit of <30 mG. These limits rule out some of the earlier accretion disc models, but remain consistent with the most recent detailed models with efficient advection. We detect marginal linear polarisation from the dust continuum, but the almost purely toroidal geometry of the polarisation vectors implies that his is due to radiatively aligned grains.
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Pisetski, V. B., i K. S. Ivanov. "Development of a fluid-dynamical model (DFM) of the Yamal Novoportovsky oiland gas-condensing deposit (based on DFM seismic data interpretation)". LITHOSPHERE (Russia) 19, nr 5 (23.11.2019): 752–66. http://dx.doi.org/10.24930/1681-9004-2019-19-5-752-766.
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Research subject. The idea of forecasting fluid-dynamical parameters is based on the views connecting the processes of sedimentation, tectonogenesis and fluid flows into an active fluid-dynamical model of the “sedimentary cover–basement” system. In such models, main fluid-dynamical parameters of oil and gas collectors, i.e. penetration and the vector of the fluid flow, are functionally connected with the components of the current state of the rock massif having a discrete (block) structure. These parameters can be calculated using DFM-interpretation technology developed by the authors in their previous works.Materials and methods. For the first time, DFM results are provided for the Yamal Novoportovsky oiland gas-condensing deposit. Here, the paleozoic basement stripped at a depth of 2700–3200 m is largely represented by metamorphic schists and marbled limestones. The basement has been covered by sediments and a platform cover since the early Jurassic age. The forecast of parameters describing modern geodynamical processes was performed on the basis of a comprehensive tectonophysical analysis of major geological and geophysical data.Results. The main axes of the neo-tectonic activity of the plate complex break the area under study into a quite regular block system that reflects a right-sided shift of fundamental blocks, that, in its turn predetermines the block shift in plate complex with the turn of the shift axis by 30 degrees. The most significant oil and gas holes in terms of influx demonstrate a connection with the described scheme of block activity. Thus, practically all high-debit boreholes were drilled in active axial zones.Conclusion. The proposed scheme of block activity satisfies the general principles of geodynamics. The developed model of abnormal pressure estimations by main productive intervals shows a good agreement with the distribution oiland gas boreholes in terms of productivity. Contact zones of active blocks present a particular interest from the standpoint of selecting the location of high-debit boreholes. These zones should be taken into account when developing new oil and gas deposits.