EXERCISES WITH INCREASING AND DECREASING MUTUAL DISTANCE BETWEEN THE TWO COURTYARDS IN DEVELOPING THE ACCURACY OF THE SERVE IN TENNIS

The research aims to identify the importance of the exercises used in the research using exercises with increasing and decreasing distance on both sides of the court, the aim of which is to develop the accuracy of the transmission in ground tennis, which is one of the most important skills of the game of tennis, as the experimental method was used for its suitability and the nature of the research, the research sample included the team of the University of Anbar In tennis for the academic year (2020-2021), they were chosen deliberately, and the following statistical methods were used: arithmetic mean, standard deviation, t-test for linked samples, t-test for unrelated samples and percentage The researchers reached the following conclusion The development of the accuracy of the serve skill in tennis. Key words:

Assessment of the Genetic Diversity of Chrysanthemum Cultivars Using SSR Markers

Chrysanthemums are undoubtedly one of the most popular flowering plants in the world. Their exceptional importance in Asian culture resulted in the global popularization of this species, which resulted in the high interest of breeders. Chrysanthemums can be divided into three groups: small-flowered, mid-flowered, and large-flowered. The exceptional economic importance and a large number of varieties make them problematic to identify, resulting in a less efficient breeding process. In the case of chrysanthemums, genotypes are almost impossible to distinguish by using phenotypic methods due to the high variation in morphological characteristics, even when they belong to the same group. The aim of the study was to evaluate the genetic diversity of 97 chrysanthemum cultivars using 14 selected SSR markers. Large-flowered varieties (Angali and Rosee D’une) were characterized by the smallest mutual distance, and the greatest distance was between large-flowered (Impact Rood) and small-flowered (Conaco Yellow) varieties. All methods of visualizing the results reveal a clear distinctiveness of small-flowered cultivars, except for the cultivars from the Moira series.

VALIDATION OF A UAV-DERIVED POINT CLOUD BY SEMANTIC CLASSIFICATION AND COMPARISON WITH TLS DATA

Recent years showed a gradual transition from terrestrial to aerial survey thanks to the development of UAV and sensors for it. Many sectors benefited by this change among which geological one; drones are flexible, cost-efficient and can support outcrops surveying in many difficult situations such as inaccessible steep and high rock faces. The experiences acquired in terrestrial survey, with total stations, GNSS or terrestrial laser scanner (TLS), are not yet completely transferred to UAV acquisition. Hence, quality comparisons are still needed. The present paper is framed in this perspective aiming to evaluate the quality of the point clouds generated by an UAV in a geological context; data analysis was conducted comparing the UAV product with the homologous acquired with a TLS system. Exploiting modern semantic classification, based on eigenfeatures and support vector machine (SVM), the two point clouds were compared in terms of density and mutual distance. The UAV survey proves its usefulness in this situation with a uniform density distribution in the whole area and producing a point cloud with a quality comparable with the more traditional TLS systems.

Decoding of EEG signals reveals non-uniformities in the neural geometry of colour

The idea of colour opponency maintains that colour vision arises through the comparison of two chromatic mechanisms, red versus green (RG) and yellow versus blue (YB). The four unique hues, red, green, blue, and yellow, are assumed to appear at the null points of these the two chromatic systems. However, whether unique hues have a distinct signature that can be reliably discerned in neural activity is still an open question. Here we hypothesise that, if unique hues represent a tractable cortical state, they should elicit more robust activity compared to non-unique hues. We use a spatiotemporal decoding approach to reconstruct an activation space for a set of unique and intermediate hues across a range of luminance values. We show that electroencephalographic (EEG) responses carry robust information about isoluminant unique hues within a 100-300 ms window from stimulus onset. Decoding is possible in both passive and active viewing tasks, but is compromised when concurrent high luminance contrast is added to the colour signals. The efficiency of hue decoding is not entirely predicted by their mutual distance in a nominally uniform colour space. Instead, the encoding space shows pivotal non-uniformities which suggest that anisotropies in neurometric hue-spaces are likely to represent perceptual unique hues. Furthermore, the neural code for hue temporally coincides with the neural code for luminance contrast, thus explaining why potential neural correlates of unique hues have remained so elusive until now.

Design of a Wireless Charging System for e-Scooter

This article deals with the design and practical evaluation of a wireless charging system for e-scooters. As wireless charging undertakes popularity, initially, the state of the art within application area is realized. Consequently, due to variability of the configuration of the whole system, several alternatives are discussed considering the utilization of the power converter stages. High attention is given to the construction of the coupling elements and calculation of the main circuit components of the considered power converters. The experimental part of the paper is supported by the measurements of key properties, i.e., the operational characteristics of the whole converter system together with coupling coils. Here, the efficiency characteristics, together with the output power characteristics in dependency on the mutual distance between the transmitting and receiving coils, are evaluated. Received results represent an adequate design approach and practical use of the proposed Wireless Power Transfer (WPT) e-scooter charging configuration.

Preparation of silver nanoparticles in a high voltage AC arc in water

The article presents for the first time the synthesis of silver nanoparticles in an electric arc of high-voltage alternating current with a frequency of 50 Hz. In particular, the method and apparatus necessary for the preparation of nanoparticles in water solution is discussed. Current–voltage characteristics depending on the mutual distance between the electrodes are presented which show a very high stability of the generated discharge phenomena. The obtained nanoparticles were examined using various analytical techniques such as UV–Vis spectroscopy, dynamic light scattering (DLS), zeta potential, energy dispersive X-Ray analysis (EDS), X-ray diffraction (XRD), and X-ray fluorescence (EDXRF). The morphology, surface and size of the obtained nanoparticles was carried out using transmission electron microscopy (TEM) and scanning TEM (STEM) equipped with the annual dark-field imaging scanning atomic-scale chemical mapping (STEM). The designed simple power supply unit consisting of an autotransformer and a microwave oven transformer (MOT) makes the preparation of silver nanoparticles both simple and economical.

Investigating close binary supermassive black holes at high angular resolution

Gravitational waves (GW) in the nano-Hz domain are expected to be radiated by close-binaries of supermassive black holes (CB-SMBHs; components bound in a Keplerian binary at mutual distance less than ~ 0.1 pc), which are relicts of galaxy mergers and anticipated to be measured via the Pulsar Timing Array (PTA) technique. The challenge of present CB-SMBH investigations is that their signatures are elusive and not easily disentangled from a single SMBH. PTAs will typically have a glimpse of an early portion of the binary inspiral to catch the frequency evolution of the binary only with sufficiently high mass and initially high eccentricity. Thus, we have to make use of electromagnetic observations to determine orbital parameters of CB-SMBHs and test nano-Hz GW properties. The 2D reverberation mapping (RM) is a powerful tool for probing kinematics and geometry of ionized gas in the SMBHs (single or binary) vicinity, yet it can lose information due to projection on the line of sight of the observer. Nevertheless, spectroastrometry with AMBER, GRAVITY, and successors can provide an independent measurement of the emitting region's size, geometry, and kinematics. These two techniques combined can resolve CB-SMBHs. In this review, we focus on RM and spectroastrometry observational signatures of CB-SMBHs with non-zero eccentricity from recent simulations with particular attention to recent developments and open issues.

Feasibility analysis for active near/far field acoustic pattern synthesis in free space and shallow water environments

In this paper, a detailed sensitivity and feasibility analysis of the active manipulation scheme for scalar Helmholtz fields proposed in our previous works, in both free space and constant-depth homogeneous ocean environments, is presented. We apply the method of moments (MoM) together with Tikhonov regularization with the Morozov discrepancy principle to investigate the effects of varying the problem parameters to the accuracy and feasibility of the proposed active field control strategy. We discuss the feasibility of the active scheme (with respect to power budget, control accuracy and process error) as a function of the frequency, the distance between the control region and the source, the mutual distance between the control regions, and the size of the control region. Process error is considered as well to investigate the possibility of an accurate active control in the presence of manufacturing or feeding noise. The numerical simulations show the accuracy of the active field control scheme and indicate some challenges and limitations for its physical implementation.

Homogenization of a non-homogeneous heat conducting fluid

We consider a non–homogeneous incompressible and heat conducting fluid confined to a 3D domain perforated by tiny holes. The ratio of the diameter of the holes and their mutual distance is critical, the former being equal to ε 3 , the latter proportional to ε, where ε is a small parameter. We identify the asymptotic limit for ε → 0, in which the momentum equation contains a friction term of Brinkman type determined uniquely by the viscosity and geometric properties of the perforation. Besides the inhomogeneity of the fluid, we allow the viscosity and the heat conductivity coefficient to depend on the temperature, where the latter is determined via the Fourier law with homogenized (oscillatory) heat conductivity coefficient that is different for the fluid and the solid holes. To the best of our knowledge, this is the first result in the critical case for the inhomogenous heat–conducting fluid.

Сontribution to the knowledge of Parabelbella (Acari, Oribatida, Damaeidae): description of two new species from Russia and the U.S.A., redescription of P. inaequipes (Banks, 1947) and a key to known species

The genus Parabelbella (Oribatida, Damaeidae), with nine known species, is distributed in the Holarctic and Neotropical regions; of these, two new species from the Russian Far East and the U.S.A. are described on the basis of adult specimens. Parabelbella rusfareastensis sp. nov. differs from Parabelbella crenatosetosa Bulanova-Zachvatkina, 1967 by the smaller body size, the absence of propodolateral apophysis, direction of notogastral seta c1, and the mutual distance between notogastral setae c. Parabelbella pseudoinaequipes sp. nov. differs from Parabelbella inaequipes (Banks, 1947) by the presence of distinctly barbed notogastral setae la and lm and sparsely barbed setae c1, c2, lp, h3, shorter and thinner dorsal notogastral setae, anterior median ventral tubercle, and by distance between insertions of seta lm–lp. The redescription of P. inaequipes is presented, based on material from the U.S.A. The main morphological traits for this species are summarized. An identification key to known species of Parabelbella is provided.