Theoretical study on forced transverse oscillations of root in soil with provision for soil’s elastic and damping properties

The topic of the paper is the theory of the forced transverse oscillations performed by the root fixed in the soil under the action of the harmonic perturbing force vectored at right angle to the root’s centreline and along the line of the translational motion performed by the lifter. On the basis of applying the Ostrogradsky-Hamilton variational principle and using the equivalent schematic model developed by the authors, the expressions have been obtained that allow to determine the amplitude of the forced transverse root body oscillations as function of the perturbing force amplitude value as well as the soil’s elastic deformation and damping coefficients. The ranges of the elastic soil deformation coefficient values, at which the resonant behaviour is observed, that is, at which the forced elastic root body oscillation amplitude value exceeds the tolerance limits, have been determined for the 10, 15 and 20 Hz frequencies of the perturbing force produced by the vibrational lifting tool. That said, the mentioned oscillation amplitude values can vary from 0.58 to 0.45 m, which is sufficient to result in the root breaking. Moreover, it has been proved that, with the increase of the perturbing force frequency, the resonant behaviour ranges shift towards the increased values of the elastic soil deformation coefficient. Therefore, such elastic soil deformation coefficient ranges should be avoided in case of the lifting tool design proposed in the paper. As regards the damping properties of the soil, it has been proved that they do not cause any resonance phenomena

Message-Passing Methods for Complex Contagions

Message-passing methods provide a powerful approach for calculating the expected size of cascades either on random networks (e.g., drawn from a configuration-model ensemble or its generalizations) asymptotically as the number $N$ of nodes becomes infinite or on specific finite-size networks. We review the message-passing approach and show how to derive it for configuration-model networks using the methods of (Dhar et al., 1997) and (Gleeson, 2008). Using this approach, we explain for such networks how to determine an analytical expression for a "cascade condition", which determines whether a global cascade will occur. We extend this approach to the message-passing methods for specific finite-size networks (Shrestha and Moore, 2014; Lokhov et al., 2015), and we derive a generalized cascade condition. Throughout this chapter, we illustrate these ideas using the Watts threshold model.Comment: 14 pages, 3 figure

Theoretical research into operation of rotary potato harvester

Received: May 25th, 2021 ; Accepted: June 22nd, 2021 ; Published: June 28th, 2021 ; Correspondence: [email protected] topic of the paper is the determination and justification of the rational design and kinematic parameters of clod breaking tools in rotary potato harvesters with the aim of improving their separating efficiency. A new mathematical model has been developed for the motion of a soil particle on the working surfaces of the cone-shaped and cylindrical vanes in the rotary tool of the new design developed by the authors. Differential equations have been generated for the motion of a soil clod as a material particle from the moment of its arrival to the surface of the vane until the moment of its departure from the said surface. As a result of the completed investigations, relations have been established between the time of contact and absolute displacement of the soil particle and the velocity of its departure from the rotor vane surface, on the one hand, and the kinematic and design parameters of the rotor, on the other hand. For example, when the machine translation velocity increases, the absolute displacement of the soil particle within the interval from the time zero to the moment of its departure from the vane surface increases from 0.59 m to 0.65 m, the velocity of soil particle departure from the vane surface - from 1.61 m s–1 to 1.81 m s–1. The highest values of the absolute displacement of the soil particle and the velocity of its departure from the vane surface are achieved at a machine translation velocity of 2.0 m s–1. The time of the contact between the material particle and the vane surface decreases with the rise of the translation velocity. When the rotor rotation frequency varies within the range from 20 min–1 to 100 min–1, the absolute velocity, with which the soil particle leaves the vane surface, rises to 4 m s–1. The duration of the contact between the material particle and the vane reaches its maximum value of 0.33 s, when the rotor rotation frequency varies within the range of 30–40 min–1

Selectivity estimation on set containment search

© Springer Nature Switzerland AG 2019. In this paper, we study the problem of selectivity estimation on set containment search. Given a query record Q and a record dataset S, we aim to accurately and efficiently estimate the selectivity of set containment search of query Q over S. The problem has many important applications in commercial fields and scientific studies. To the best of our knowledge, this is the first work to study this important problem. We first extend existing distinct value estimating techniques to solve this problem and develop an inverted list and G-KMV sketch based approach IL-GKMV. We analyse that the performance of IL-GKMV degrades with the increase of vocabulary size. Motivated by limitations of existing techniques and the inherent challenges of the problem, we resort to developing effective and efficient sampling approaches and propose an ordered trie structure based sampling approach named OT-Sampling. OT-Sampling partitions records based on element frequency and occurrence patterns and is significantly more accurate compared with simple random sampling method and IL-GKMV. To further enhance performance, a divide-and-conquer based sampling approach, DC-Sampling, is presented with an inclusion/exclusion prefix to explore the pruning opportunities. We theoretically analyse the proposed techniques regarding various accuracy estimators. Our comprehensive experiments on 6 real datasets verify the effectiveness and efficiency of our proposed techniques

Structural trace of adaptation in motive nuclei of spinal cord of rats in hypokinesia and after physical loading in the recovery period

The purpose of this paper is to study the morphological changes of neurocytes in spinal cord of rats in hypokinesia and subsequent physical loading. Studies were performed on 55 laboratory rats of Wistar line. Materials of the research were the anterior horns of the gray matter of L5-S2 spinal segments. Preparations stained by Nissl and Viktorov were examined histologically. Hypokinesia was modeled following on the author’s technique. It was established that during prolonged hypokinesia in neurocytes of spinal cord of rats morphological changes in cell size and shape of the motor nuclei of all segments under study have been recorded. The number of hypochromic, hyperchromic destructively unchanged and hyperchromic destructively altered neurocytes increase; shadow cells appears, as well as cases of satellitosis and neuronophagia. Decrease in of albumen synthetical neurocyte function has been recorded. Physical loading of the average aerobic capacity leads to normalization of structural and functional state of neurocytes and enhances the reparative processes, as evidenced by a number of positive changes in morphometric parameters: increase in the number of normochromic neurocytes and decreasing the number of hyper- and hypochromic neurocytes with destructive signs, absence of pyknotic forms. Morphological parameters of neurocytes and their nuclei after physical loading of average aerobic capacity do not differ from those in the control group of intact animals. In neurocytes of this group of rats RNA concentration increases by 12.6% compared to animals after prolonged hypokinesia. Neurocytes of spinal cord of rats after prolonged hypokinesia develop significant morphological changes which are characterized by emergence of a significant number of hyperchromic neurocytes with signs of destructive changes and shadow cells, as well as and hypochromic neurocytes with signs of destructive changes, reduction in size and change of shape of perikaryons of neurocytes and their nuclei. Morphological changes of neurocytes after prolonged hypokinesia are accompanied by violations of biosynthetic processes, as evidenced by RNA decrease in the cytoplasm of efferent neurocytes of spinal cord of rats. Physical loading of average aerobic capacity leads to normalization of structural and functional state of neurocytes and promotes the reparative processes suported by positive changes in morphometric parameters

Prevention of the Dissemination of the Ideology of Extremism and Terrorism through State Youth Policy

В статье рассмотрены вопросы осуществления работ по противодействию идеологии экстремизма и терроризма в молодежной среде. Авторами проанализированы понятия «экстремизм» и «терроризм», развитие террористической деятельности на современном этапе. Представлены способы работы, направленные на воспитание правовой культуры молодежи. Проанализирована деятельность отряда «Кибердружина».The article discusses issues on the implementation of work on countering the ideology of extremism and terrorism in a youth environment. The authors analyzed the concepts of “extremism” and “terrorism”, the development of terrorist activities at the present stage. The paper presents ways to work aimed at raising the legal culture of young people. Analyzed the activity of the “Cyberdip” squad

Extracellular Vesicles in Musculoskeletal Pathologies and Regeneration

The incidence of musculoskeletal diseases is steadily increasing with aging of the population. In the past years, extracellular vesicles (EVs) have gained attention in musculoskeletal research. EVs have been associated with various musculoskeletal pathologies as well as suggested as treatment option. EVs play a pivotal role in communication between cells and their environment. Thereby, the EV cargo is highly dependent on their cellular origin. In this review, we summarize putative mechanisms by which EVs can contribute to musculoskeletal tissue homeostasis, regeneration and disease, in particular matrix remodeling and mineralization, pro-angiogenic effects and immunomodulatory activities. Mesenchymal stromal cells (MSCs) present the most frequently used cell source for EV generation for musculoskeletal applications, and herein we discuss how the MSC phenotype can influence the cargo and thus the regenerative potential of EVs. Induced pluripotent stem cell-derived mesenchymal progenitor cells (iMPs) may overcome current limitations of MSCs, and iMP-derived EVs are discussed as an alternative strategy. In the last part of the article, we focus on therapeutic applications of EVs and discuss both practical considerations for EV production and the current state of EV-based therapies

Theoretical investigation of a rear-mounted linkage for wide-span tractors

The work is devoted to the investigation of the peculiarities of aggregation of wide-span tractors (vehicles) with agricultural machines and implements. As a result of the conducted studies, it has been established that, from the point of view of the control impact (the turning angle of the driven wheels) and the disturbing impact (the turning angle of the mounted implement in a horizontal plane) exerted by the wide-span tractor, the most desirable is such a variant of configuration of the mounted device in which the instantaneous centre of rotation, formed by the convergence rays of its lower links, is in the centre of the mass of the tractor. When using wide-span tractors(vehicles) with mounted implements of the high 4N and 4 categories in accordance with the ISO 730: 2009, one should consider a possibility to configure them both for a three-point and a two-point scheme