Characteristic Of Fields Research Articles

Numerical study of the upwelling and downwelling effects of artificial reefs along tidal cycles in the Pearl River Estuary

Artificial reefs (ARs) are a preferred option for managers due to their distinctive hydrodynamic properties, which support a highly productive local ecosystem. However, the hydrodynamics characteristics of ARs in natural marine environments have not been conducted. Being the first to explore the spatiotemporal characteristic of flow fields around ARs along tidal cycles in marine environments, this study redefined the upwelling and downwelling of ARs, based on natural vertical velocities, and separated the upwelling into co-direction upwelling and re-direction upwelling, and the downwelling into co-direction downwelling and re-direction downwelling. This study simulated the flow field in the Wanshan ARs area of the Pearl River Estuary along the tidal cycles using the MIKE3-FM. Numerical simulations revealed that (1) co-direction upwelling and co-direction downwelling were the dominant components of the vertical flow field effects of ARs; (2) the areas sum of upwelling and downwelling were largest in the medium water column, with about 1.6 and 1.03 times as large as the bottom and surface water column, respectively, while the fluxes sum of the upwelling and downwelling were largest in bottom water column, with approximately 1.3 and 2.2 times larger than those in the middle and surface water columns; (3) the area and volume of the upwelling and downwelling gradually decreased along neap-spring tide, exhibited significantly negative correlations with current speeds; while the upwelling flux and downwelling flux gradually increased along neap-spring tide; exhibited a significantly positive correlation with current speed; (4) the effects of tide to upwelling and downwelling of AR are forced by the northward velocity of current speed, the net flux of upwelling and downwelling showed a significant positive correlation with the northward velocity of current speed (r = 0.94). These results could provide a reference for assessing the flow field effect of ARs and a guide for the configuration and management of ARs.

THE DEVELOPMENT OF ECOLOGICAL THINKING IN PRACTICAL ACTIVITIES AND ENSURING THE FUNCTIONING OF THE ECONOMY IN ACCORDANCE WITH THE REQUIREMENTS OF ENVIRONMENTAL PROTECTION

The deterioration of the majority of ecosystems in the biosphere, significant reduction in bioproductivity and biodiversity, catastrophic depletion of soils and mineral resources due to unprecedented pollution of the Earth's surface, hydrosphere, and atmosphere, are all linked to the intensive growth of the global population and the development of scientific and technological progress over the past 50 years. The necessity to meet the ever-increasing needs of human society has led to a tremendous expansion of economic activities, changes in the proportions of the world economy, production capacities, techniques, and technologies, as well as the variety of products and consumption patterns. The production and consumption models that have emerged in the world no longer correspond to the conditions of sustainable coexistence between humans and nature. The analysis of the state of the natural environment indicates that in recent years, there have been no significant positive shifts in the ecological situation, and in some areas, it has even worsened. The high concentration of industry and agriculture, along with ecologically unjustified economic activities, have made Ukraine one of the most environmentally troubled countries in Europe. The situation was significantly exacerbated by the Chernobyl nuclear power plant accident and the armed conflict in Ukraine. The aim of the article is to develop of ecological thinking involves aligning human practical activities with the laws of nature and ensuring that the economy operates in accordance with the requirements of environmental preservation. The study of human ecology is an interdisciplinary science that focuses on a clearly defined and specific set of issues. In its research, it utilizes both general scientific methods (grounded in philosophical and general scientific principles) and specific methods (characteristic of certain fields of scientific activity). General scientific methods include empirical research methods (observation, measurement, comparison) and empirical-theoretical methods (abstraction, analysis, synthesis, induction, deduction, analogy, modeling) as well as theoretical methods (ascending from abstract to concrete, forecasting, systematic approach). The most specific method used in the study of human ecology is anthropoecological monitoring, a system of observations of changes in human life processes in connection with environmental factors' impact on them. It also involves monitoring and evaluating environmental conditions that negatively affect population health and contribute to the spread of diseases. The article systematizes the main threats to economic security in Ukraine and describes their main consequences. In further research, the author's efforts will be focused on the development of measures to neutralize the impact of these threats on the ecological security of Ukraine.

Hygienic characteristic of magnetic fields at different arc welding methods

Hygienic characteristic of magnetic fields at different arc welding methods

Гігієнічна характеристика магнітних полів при різних способах дугового зварювання

Гігієнічна характеристика магнітних полів при різних способах дугового зварювання

Understanding the Impact of Reservoir Low-Permeability Subdomains in the Steam Injection Process

Optimizing production in the mature fields of heavy oil reservoirs is still challenging. In most cases, conventional recovery techniques are not effective, although they are suitable for applying thermal recovery methods. Steam injection involves injecting steam into the reservoir where the heat exchange with the oil occurs. This promotes a reduction in oil viscosity and thus increases its mobility. One of the challenges of the EOR project is understanding how the presence of regions with contrasting properties, such as fractures, caves, and barriers, could affect the steam flow. This work investigates the impact of low-permeability barriers in the steam injection process. The barriers were created on a semi-synthetic reservoir characteristic of Brazilian onshore mature fields. We used the three-phase pseudo-compositional reservoir simulation STARS (Steam Thermal Advanced Processes Reservoir Simulation) for simulations. Our results show that the shape, number, and arrangement of barriers in a porous medium can affect the amount of oil recovered. They may also be able to anticipate or delay oil production.

Spatial Coherence Manipulation on the Disorder-Engineered Statistical Photonic Platform.

Coherence, similar to amplitude, polarization, and phase, is a fundamental characteristic of the light fields and is dominated by the statistical optical property. Although spatial coherence is one of the pivotal optical dimensions, it has not been significantly manipulated on the photonic platform. Here, we theoretically and experimentally manipulate the spatial coherence of light fields by loading different random phase distributions onto the wavefront with a metasurface. We achieve the generation of partially coherent light with a predefined degree of coherence and continuously modulate it from coherent to incoherent by controlling the phase fluctuation ranges or the beam sizes. This design strategy can be easily extended to manipulate arbitrary phase-only special beams with the same degree of coherence. Our approach provides straightforward rules to manipulate the coherence of light fields in an extra-cavity-based manner and paves the way for further applications in ghost imaging and information transmission in turbulent media.

3D Navigation Control of Untethered Magnetic Microrobot in Centimeter-Scale Workspace Based on Field-of-View Tracking Scheme

Automatic 3D navigation control of microrobot in large microenvironment is one of the primary challenges hindering its applications. In this article, we present a systematic approach to use an electromagnetic manipulation system to deal with this challenge. Two movable orthogonal microscopic cameras scan the microenvironment on the top view and side view to build a stereo occupancy map automatically. The initial position of microrobot can be located on the basis of the similarity curves generated by the scanning sequences. In accordance with the distribution characteristic of electromagnetic fields in workspace, an enhanced rapidly exploring random tree algorithm is proposed to avoid obstacles in the complex environment. To ensure continuous visual servo in wide range, a field-of-view tracking method is developed using a specific image definition evaluation algorithm. A prescribed performance controller with disturbance observer is designed, which guarantees that the microrobot can remain in the view of microscopic cameras, and the transient and steady-state performance of the system can satisfy the expected requirements. A set of experiments are performed to verify the effectiveness of the proposed automatic 3D navigation strategy. Experimental results show that the microrobot can navigate automatically in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{12}\,\times 10\,\times \text{10-mm}$</tex-math></inline-formula> microenvironment containing obstacles, and achieve reliable field-of-view tracking and path following at high speed.

The effect of temperature fields on soil and plant cover formation in arid ecosystems of the Uvs Nuur basin

Introduction of remote and automated methods into the practice of soil and ecological studies urges for development of the methodological basis for combined analyses of surface and satellite data. The aim of the study was to explore the possibility to identify and typologise the structural and functional borders of soil cover using temperature fields, obtained by combined analysis of the temperature time series obtained by field and remote temperature monitoring. The functional relationships that are expressed within geosystems as the flux of energy and matter are reflected in soil temperature regimes, hydrophysical soil properties and plant cover biological productivity, which were studied in the arid ecosystems of the Uvs Nuur depression in Tuva, Russia. The quantitative characteristic of the temperature fields of the psammophytic soils were obtained, and the effect of hydrothermal conditions and soil hydrophysical properties on above- and belowground phytomass stocks of the sand massif Zuger-Els revealed and discussed.

ОСНОВНЫЕ ЭТАПЫ ГЕОЛОГИЧЕСКОГО ОСВОЕНИЯ ШЕЛЬФА КАСПИЙСКОГО МОРЯ

The article gives a brief overview of the shelf zone of the northern part of the Caspian Sea and presents general physical and geographical information of the study region. The general history of oil production in the Caspian Sea is given, as well as new hydrocarbon deposits on the shelf of the northern Caspian are listed. A modern characteristic of oil and gas fields in the northern Caspian (Russian sector) is given. The issues of the ecological situation that have developed at the present time in the shelf zone are considered. The role of environmental safety at the present stage of solving the problem has been substantiated.

Superior and versatile interface transition layer with a sandwich-like multiscale rigid-soft dual-locked structure for high performance composites

In order to integrate eco-friendly, flexible and versatile purpose into interphase design strategy, a multiscale rigid-soft dual-locked interface layer with sandwich structure was designed and fabricated to modify the interface between carbon fibers (CFs) and matrix by a facile and green method, with water as the only solvent. Polydopamine (PDA) was chosen as a functional platform to introduce Ni(OH)2 nanosheets self-assembling onto the CFs surface. After incorporation with a soft and amine-rich polymer, a steadier and more entangled dual-locked interface layer could be realized. The interlaminar shear strength (ILSS) results indicated that the ILSS improved up to 43.38%, compared with untreated CFs composites, the flexural properties represented a dramatic breakthrough, indicating the superiority of this interfacial network. Interestingly, this design strategy could be extended to other system due to the versatile characteristic of PDA and cater different application fields by varying functional nanoparticles.

Lyapunov Control of Quantum Systems Based on Energy-Level Connectivity Graphs

This paper proposes a new multilayer Lyapunov control scheme based on energy-level connectivity graphs of quantum systems, which enables a high-probability population transfer to any eigenstate in high-dimensional quantum systems. We provide a graph connectivity result for stability analysis and explore the selectivity characteristic of the Lyapunov control fields. A systematic layering method for the energy-level connectivity graph is presented to achieve a layer-by-layer population transfer to the target state. Several applications including a five-level quantum system, a three-qubit superconducting system, and a spin chain of five qubits are presented to demonstrate the effectiveness of the multilayer Lyapunov control method.

Quantifying Process Nonclassicality in Bosonic Fields**Supported by the Young Scientists Fund of the National Natural Science Foundation of China under Grant No 11605006, the National Natural Science Foundation of China under Grant No 11875317, the National Center for Mathematics and Interdisciplinary Sciences of Chinese Academy of Sciences under Grant No Y029152K51, and the Key Laboratory of Random Complex Structures and

Nonclassicality of optical states, as a key characteristic of bosonic fields, is a valuable resource for quantum information processing. We investigate the generation of nonclassicality in quantum processes from a quantitative perspective, introduce three information-theoretic measures of nonclassicality for quantum-optical processes based on the Wigner–Yanase skew information and coherent states, and illustrate their physical significance through several well-known single-mode quantum processes.

Density maps of geophysical study as a new type of integrated characteristic of geophysical fields in atlases

Abstract. Nowadays the geophysical section of traditional atlases is not sufficiently informative. The amount of geophysical fields’ maps rarely exceeds two. On the other hand, the electronic GIS atlases invariably include in their composition maps of study of geophysical observations, which make it possible to assess the level of exploration on the mapped territory. The creation and design of such maps today are limited to displaying only the factual location of observation profiles and other objects. In order to expand the possibilities of analyzing geophysical information, the authors suggests a method for creating of density maps of geophysical study. The study on these maps is shown with isolines – usual method for geophysical maps. The authors of this article describe the method of creating density maps of geophysical study. This method includes the following steps: selection and analysis of information sources of geophysical study; choice of study parameters for mapping; calculation of the density of objects of geophysical study; interpolation and creation of isolines of objects of geophysical study density. The created study maps of density dynamics represent the approbation of the method; they allow increasing the information content of geophysical section of the atlas. The study is also a special factor that determines general need of mapping the phenomenon and characterizes the availability of data sources for mapping. Therefore, the opportunities for using developed maps for the automated determination of the atlas structure are also shown in the article.

Topology and geometry of Gaussian random fields I: on Betti numbers, Euler characteristic, and Minkowski functionals

This study presents a numerical analysis of the topology of a set of cosmologically interesting three-dimensional Gaussian random fields in terms of their Betti numbers $\beta_0$, $\beta_1$ and $\beta_2$. We show that Betti numbers entail a considerably richer characterization of the topology of the primordial density field. Of particular interest is that Betti numbers specify which topological features - islands, cavities or tunnels - define its spatial structure. A principal characteristic of Gaussian fields is that the three Betti numbers dominate the topology at different density ranges. At extreme density levels, the topology is dominated by a single class of features. At low levels this is a \emph{Swiss-cheeselike} topology, dominated by isolated cavities, at high levels a predominantly \emph{Meatball-like} topology of isolated objects. At moderate density levels, two Betti number define a more \emph{Sponge-like} topology. At mean density, the topology even needs three Betti numbers, quantifying a field consisting of several disconnected complexes, not of one connected and percolating overdensity. A {\it second} important aspect of Betti number statistics is that they are sensitive to the power spectrum. It reveals a monotonic trend in which at a moderate density range a lower spectral index corresponds to a considerably higher (relative) population of cavities and islands. We also assess the level of complementary information that Betti numbers represent, in addition to conventional measures such as Minkowski functionals. To this end, we include an extensive description of the Gaussian Kinematic Formula (GKF), which represents a major theoretical underpinning for this discussion.

A new extrapolation expression for exposure evaluation inside a human-equivalent liquid phantom in the vicinity of wireless power transfer systems

To ensure human safety against electromagnetic exposures from wireless power transfer (WPT) systems operating at MHz-band frequencies, a compliance test must be conducted using either numerical simulations or measurements. In practice, measurements of the specific absorption rate (SAR) inside a human-equivalent liquid phantom are required for exposure evaluation. However, accurate measurements of SAR are difficult, especially at a location close to the phantom boundary, owing to the boundary effect, caused by the field disturbance due to the SAR probe itself. Hence, it is necessary to use an extrapolation method to determine the internal electric field or SAR. In this study, we propose a new extrapolation expression based on the characteristic of electromagnetic fields inside the phantom in order to estimate internal electric field strength or SAR. The validity of the proposed expression was demonstrated both numerically and experimentally. From the results, we confirmed that the difference in the internal electric field strength inside a liquid phantom was less than 3% between our proposed extrapolation expression and the method of moments (MoM). For SAR measurements using two types of actual WPT systems, i.e., solenoid and flat-spiral types, we found that the proposed expression can be used to evaluate the spatial peak 10-g average SAR with a difference of less than 30% compared with those numerically obtained by MoM.

Двойственность в абелевых многообразиях и формальных группах над локальными полями

Статья посвящена памяти Олега Николаевича Введенского (1937 – 1981 гг.). О. Н. Введенский был учеником академика И. Р. Шафаревича. Исследования О. Н. и полученные им результаты связаны с двойственностью в эллиптических кривых и с соответствующими когомологиями Галуа над локальными полями, со спариванием Шафаревича-Тэйта и с другими спариваниями, с локальной и квази-локальной теорией полей классов эллиптических кривых, с теорией абелевых многообразий размерности больше 1, с теорией коммутативных формальных групп над локальными полями. Представлены как результаты, полученные О. Н. Введенским, так и новые избранные результаты, развивающие исследования в направлениях фундаментальных групп схем, главных однородных пространств (торсеров) и двойственности. Первая часть статьи, представлення здесь, является введением как в результаты, полученные О. Н. Введенским в направлении двойственности абелевых многообразий и формальных групп, так и в новые избранные результаты, развивающие исследования в направлениях фундаментальных групп схем, главных однородных пространств (торсеров) и двойственности. Во Введении приведены предварительные сведения и представлено содержание статьи. В первом разделе дан краткий обзор избранных результатов по теории алгебраических, квазиалгебраические и проалгебраические группы и групповых схем. Далее, в разделе 2 преставлены избранные результаты по фундаментальным группам алгебраических многообразий, по фундаментальным группам схем, а в разделе 3 - избранные результаты о главных однородных пространствах (торсерах), развивающие исследования О. Н. и других авторов. Термин торсер мы используем как перевод на русский язык в редакции И.Р. Шафаревича английского термина torsor. В разделе 4 даны сведения о двойственности, а в разделе 5 представлены результаты О. Н. по арифметической теории формальных групп и их развитие. Результаты, этого раздела, представленные над локальными и квази-локальными полями K, над их кольцами целых, и над их полями вычетов k, связанны (1) с формальной структурой абелевых многообразий, (2) с коммутативными формальными группами, (3) с соответствующими гомоморфизмами и изогениями. В статье алгебраические многообразия, абелевы схемы и коммутативные формальные групповые схемы определены, как правило, над локальными и квази-локальными полями, над их кольцами целых, и над их полями вычетов. Но кратко рассматриваются эти объектыи и над глобальными полями, так как О. Н. интересовала тематика алгебраических многообразий над глобальными полями и он проводил соответствующие исследования. Предполагается, что характеристика полей вычетов больше 3, если не оговаривается иное.Я признателен В.Н. Чубарикову за предложение опубликовать статью в сборнике.Особая признательность Н. М. Добровольскому за помощь и поддержку в процессе подготовки статьи к печати.

Analysis of Influence of the Inner Diameter of the Permanent Magnet on Rotor Stress and Critical Speed for the High Speed Permanent Magnet Motor

While the rotor of a high-speed permanent magnet motor runs at high speed, it is difficult for the permanent magnet to bear the huge tensile stress which caused by centrifugal force. In addition, the rotor is also prone to vibration and even bending deformation due to resonance. Therefore, the strength and critical speed of the rotor must be analyzed and checked. In this paper, because of the slim characteristic of high speed permanent magnet rotors, the displacement and stress fields of a 150 kW, 30 000 r/min surface mounted high speed permanent magnet motor rotor are deduced based on the theory of the thick-walled cylinder. The finite element method is used to verify the correctness of the analytical calculation. Based on the deduced analytical formulas, the influences of the inner diameter of the permanent magnet and the sleeve material on the rotor stress are analyzed. At the same time, the finite element method is used to calculate the critical speed of the rotor and analysis the influences of the inner diameter of the permanent magnet and the sleeve material on the critical speed of the rotor shaft system. A basis for the design of the high speed permanent magnet motor rotor is given.

Mapping Global Health: A network analysis of a heterogeneous publication domain

This paper examines one of the most visible but oddly neglected aspects of the rapidly expanding Global Health (GH) enterprise: its vast literature. Basing our data on the PubMed MeSH term “World Health” (changed to “Global Health” in 2015) and utilizing the citation and funding metadata provided by Web of Science, we analyze nearly 20,000 articles using the software platform CorTexT for the automatic processing of large text corpora. We perform several types of scientometric network analyses, and provide maps displaying inter-citations among journals publishing GH articles, co-authorship among the 292 authors who published 12 or more papers, co-citation analysis of works (articles, books, and reports) cited at least 30 times by the papers in our database, and funding sources since 2008. The maps display the social, cognitive, and funding substructure of the GH publication field. We suggest that this somewhat fragmented and fuzzy domain is held together by (1) a core group of authors who have for some time been co-authoring numerous papers and reports with one another; (2) several central journals, most notably the Lancet, addressing wider audiences and transcending the narrow specialization characteristic of scientific and biomedical fields; and (3) a growing body of large-data metrics, most prominently the Global Burden of Disease, which has become a rhetorical resource for numerous groups with different agendas.

Stiefel-Whitney classes of curve covers

Let \(D\) be a Dedekind scheme with the characteristic of all residue fields not equal to 2. To every tame cover \(C\to D\) with only odd ramification we associate a second Stiefel-Whitney class in the second cohomology with mod 2 coefficients of a certain tame orbicurve \([D]\) associated to \(D\). This class is then related to the pull-back of the second Stiefel-Whitney class of the push-forward of the line bundle of half of the ramification divisor. This shows (indirectly) that our Stiefel-Whitney class is the pull-back of a sum of cohomology classes considered by Esnault, Kahn and Viehweg in ‘Coverings with odd ramification and Stiefel-Whitney classes’. Perhaps more importantly, in the case of a proper and smooth curve over an algebraically closed field, our Stiefel-Whitney class is shown to be the pull-back of an invariant considered by Serre in ‘Revetements a ramification impaire et theta-caracteristiques’, and in this case our arguments give a new proof of the main result of that article.

Homogenization in probabilistic terms: The variational principle and some approximate solutions

Studying of materials with evolving random microstructures requires the knowledge of probabilistic characteristics of local fields because the path of the microstructure evolution is controlled by the local fields. The probabilistic characteristics of local fields are determined by the probabilistic characteristics of material properties. In this paper it is considered the problem of finding the probabilistic characteristic of local fields, if the probabilistic characteristics of material properties are given. The probabilistic characteristics of local fields are sought from the variational principle for probabilistic measure. Minimizers of this variational problem provide all statistical information of local fields as well as the effective coefficients. Approximate solutions are obtained for electric current in composites for two cases: multi-phase isotropic composites with lognormal distribution of conductivities and two-phase isotropic composites. The solutions contain a lot of statistical information that has not been available previously by analytical treatments.