Reconstruction of large scale flow structures in a stirred tank from limited sensor data

We combine reduced order modelling and system identification to reconstruct the temporal evolution of large scale vortical structures behind the blades of a Rushton impeller. We performed Direct Numerical Simulations at Reynolds number 600 and employed proper orthogonal decomposition (POD) to extract the dominant modes and their temporal coefficients. We then applied the identification algorithm, N4SID, to construct an estimator that captures the relation between the velocity signals at sensor points (input) and the POD coefficients (output). We show that the first pair of modes can be very well reconstructed using the velocity time signal from even a single sensor point. A larger number of points improves accuracy and robustness, and also leads to better reconstruction for the second pair of POD modes. Application of the estimator derived at Re=600 to the flows at Re=500 and 700, shows that it is robust with respect to changes in operating conditions

Exact computation of one-loop correction to energy of pulsating strings in AdS_5 x S^5

In the present paper, which is a sequel to arXiv:1001:4018, we compute the one-loop correction to the energy of pulsating string solutions in AdS_5 x S^5. We show that, as for rigid spinning string elliptic solutions, the fluctuation operators for pulsating solutions can be also put into the single-gap Lame' form. A novel aspect of pulsating solutions is that the one-loop correction to their energy is expressed in terms of the stability angles of the quadratic fluctuation operators. We explicitly study the "short string" limit of the corresponding one-loop energies, demonstrating a certain universality of the form of the energy of "small" semiclassical strings. Our results may help to shed light on the structure of strong-coupling expansion of anomalous dimensions of dual gauge theory operators.Comment: 49 pages; v2: appendix F and note about antiperiodic fermions added, typos corrected, references adde

The technology of contactless electromagnetic acoustic transmission and reception of ultrasonic waves in metals

The basic principles of technology EMAT are transformation mechanisms, the influence of the magnetizing field on the EMAT transformation, common structures of transducers. Special attention is paid to the transmission and reception of ultrasonic waves in ferromagnetic materials, modern methods and developments improving the efficiency of EMAT transformation under the control of ferromagnetic objects of any thickness are given.Рассматриваются основные принципы ЭМА технологии: механизмы ЭМА преобразования, влияние подмагничивающего поля на ЭМА преобразование, распространенные конструкции ЭМА преобразователей. Особое внимание уделено возбуждению и приему ультразвуковых волн в ферромагнетиках, приведены современные способы и разработки, позволяющие повысить эффективность ЭМА преобразования при контроле ферромагнитных объектов любой толщины

ANKLE JOINT REPLACEMENT (REVIEW)

Ankle joint replacement remains the most promising but at the same time one of the most challenging fields of orthopedics. In this article the authors analyzed the history of ankle joint replacement development with meticulous details of the prosthesis structure as well as complications occurring with different generations of the prosthesis. Major tendencies of development and improvements of the prosthesis are described while taking into account the complicated biomechanics of the ankle joint. Based on the completed analysis the conclusion was made that using new materials in combination with improved structure allows for major improvements in the ankle joint replacement

Carbon Sequestration Dynamics in Urban-Adjacent Forests: A 50-Year Analysis

Achieving carbon neutrality is crucial for urban ecosystems. Forests growing near cities largely determine the state of the environment in urban areas. The aim of the present research is to assess the carbon productivity dynamics in forests near Krasnoyarsk (a large industrial center) over a 50-year period in terms of carbon sequestration and conservation. The study was based on forest inventory conducted in Karaul'noe Forestry in 1972, 1982, and 2002 and forest inventory covering six forest compartments in 2022. The forest covers 3980 ha and consists of 52 forest compartments. The analysis was based on the assessment of carbon productivity dynamics and followed four levels of principles: forestry, structure, forest compartment, and forest stand. The research was based on forest fund dynamics, analyzing methods, long-term forest inventory, assessing carbon stock, and growing stock dynamics. Pine is the dominant forest-forming species that absorbs the most carbon in the study area. Pine is long-lived, covers a vast area, and has the highest carbon sequestration potential. At the forest structure level, the predominant carbon pools are mid-late successional and late successional stands dominated by pine, birch, and aspen. Forest compartment-level analysis revealed three trends in carbon sequestration: carbon balance, a decrease in carbon sequestration, and an increase in carbon sequestration. Notably, the prevailing trend is determined by changes in carbon sequestration by dominant forest-forming species (pine). Forest stand-level analysis showed that stands have become more and more uneven-aged. About 65% of total carbon stock is concentrated in mid successional, mid-late successional and late-successional stands, and 35% in young stands. The carbon sequestration rate decreases in forests with age. However, pine forests increase biological productivity and continue to successfully sequester carbon. Deciduous forests have lost their carbon sequestration potential, and the area they occupy is currently decreasing in the study area. The development of the young generation in pine stands suggests that the carbon sequestration potential in forests growing near the city will not decrease and may even increase due to climate change. Doi: 10.28991/CEJ-2023-09-09-08 Full Text: PD

Stevioside prevents oxidative stress in wheat seedlings

© 2015, Pleiades Publishing, Ltd. This is the first study on the effect of stevioside, a diterpene glycoside that is a new promising plant growth regulator, on the antioxidant and photosynthetic systems of seedlings of the winter wheat cultivar Kazanskaya 560. Stevioside has been demonstrated to cause a decrease in the malondialdehyde formation rate, an increase in the activities of antioxidant enzymes (peroxidase and ascorbate peroxidase), and the accumulation of proline and carotenoids. Apparently, this integrated effect of stevioside can prevent oxidative stress caused by adverse environmental factors in plants

Symmetry Breaking in Pyrrolo[3,2-b]pyrroles: Synthesis, Solvatofluorochromism and Two-photon Absorption

Five centrosymmetric and one dipolar pyrrolo[3,2-b]pyrroles, possessing either two or one strongly electron-withdrawing nitro group have been synthesized in a straightforward manner from simple building blocks. For the symmetric compounds, the nitroaryl groups induced spontaneous breaking of inversion symmetry in the excited state, thereby leading to large solvatofluorochromism. To study the origin of this effect, the series employed peripheral structural motifs that control the degree of conjugation via altering of dihedral angle between the 4-nitrophenyl moiety and the electron-rich core. We observed that for compounds with a larger dihedral angle, the fluorescence quantum yield decreased quickly when exposed to even moderately polar solvents. Reducing the dihedral angle (i.e., placing the nitrobenzene moiety in the same plane as the rest of the molecule) moderated the dependence on solvent polarity so that the dye exhibited significant emission, even in THF. To investigate at what stage the symmetry breaking occurs, we measured two-photon absorption (2PA) spectra and 2PA cross-sections (sigma(2PA)) for all six compounds. The 2PA transition profile of the dipolar pyrrolo[3,2-b]pyrrole, followed the corresponding one-photon absorption (1PA) spectrum, which provided an estimate of the change of the permanent electric dipole upon transition, approximate to 18D. The nominally symmetric compounds displayed an allowed 2PA transition in the wavelength range of 700-900nm. The expansion via a triple bond resulted in the largest peak value, sigma(2PA)=770GM, whereas altering the dihedral angle had no effect other than reducing the peak value two- or even three-fold. In the S0S1 transition region, the symmetric structures also showed a partial overlap between 2PA and 1PA transitions in the long-wavelength wing of the band, from which a tentative, relatively small dipole moment change, 2-7D, was deduced, thus suggesting that some small symmetry breaking may be possible in the ground state, even before major symmetry breaking occurs in the excited state.1111Ysciescopu