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This research proposition introduces a novel microstrip antenna design that features triple notches for ultra-wideband (UWB) applications. The antenna, measuring 35.4 mm × 28.82 mm × 1.57 mm, incorporates rectangular and semi-circular slots, as well as a pentagonal stub. A modified U-shaped slot on the pentagonal stub creates one notched frequency band at 3.3–3.7 GHz. Additionally, two Split Ring Resonators (SRRs) are integrated into the antenna's rear surface, resulting in two more notched bands at 5.1–5.8 GHz and 7.1–7.8 GHz. Operating within a frequency range from 3 to 11.2 GHz with VSWR ≤ 2, the antenna effectively excludes the triple stop bands at 3.3–3.7 GHz (11.4%), 5.1–5.8 GHz (12.8%) and 7.1–7.8 GHz (9.4%). The proposed antenna has been successfully prototyped and verified. An extensive result analysis has been conducted, confirming that the developed antenna is suitable for application in a range of wireless systems. Moreover, the article includes the implementation of an equivalent circuit for the proposed antenna. [ABSTRACT FROM AUTHOR]

Designing an electromagnetic radiating element that can enhance the capacity of a device operating with multiple frequencies simultaneously, while maintaining its compactness and compatibility with customer premise equipment, is a significant challenge. To tackle this issue, this work proposes a multiple input multiple output (MIMO) antenna with eight elements placed 45° apart on a Rogers 5880 substrate which has been micromachined from sixteen edges with a thickness of 0.252 mm. The substrate measures the area of 717.46 mm2 boasting a dielectric constant of 2.2 and loss tangent of 0.0009 with a unique star shape. The slot technique improves the return loss accompanied by defected ground structure to achieve dual-band operation at 28.1 GHz (n261) with the impedance bandwidth from 27.95 to 28.4 (0.45 GHz) and 39.5 GHz (n260) having impedance bandwidth from 38.6 to 40.4(1.8 GHz). The inter-element isolation of more than 60 dB is achieved for both bands with micromachined substrate. The measured gain at 28 GHz is 7dBi and at 39 GHz it is obtained as 7.4dBi. The 8-port MIMO is simulated for all the diversity metrics such as Diversity Gain (DG), Channel Capacity Loss (CCL), Envelope Correlation Coefficient (ECC), Mean Effective Gain, Total Active Reflection Co-efficient (TARC). The parameters evaluated for all eight ports are within the standard values with ECC of < 0.001, DG > 9.99 dB, CCL < 0.1b/s/Hz, and the TARC < − 10 dB. The MIMO has been fabricated and tested for various results which favourably aligned with the simulated results validating the applicability of the proposed mm-Wave 8-port MIMO antenna for practical 5G applications. Furthermore, the 8-port is also simulated for conformality check which showed a minor change in impedance bandwidth at 15°, 30°, and 45°. The Specific Absorption Ratio (SAR) analysis has provided values less than 1.6 W/kg for both the intended bands. The conformal and SAR analysis has added an advantage to the application of the proposed antenna for 5G as well as for wearable on-body applications. [ABSTRACT FROM AUTHOR]

Copyright of Scientia Iranica. Transaction D, Computer Science & Engineering & Electrical Engineering is the property of Scientia Iranica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research explores the efficacy of a passive control strategy designed to enhance the performance of an axial hollow fan. This investigation uses a dedicated experimental setup to evaluate various aspects of the fan's performance, including characteristics, efficiency, acoustic emissions, and flow topology. The control strategy involves introducing a portion of the main flow into the hollow fan through an upstream opening in the hub. Capitalizing on centrifugal forces, this air portion is injected into the fan's periphery via an axial slot at the rotating shroud ring. Additionally, to refine the previous strategy, a centrifugal fan is incorporated into the hub to assist in directing the flow toward the hollow blades and effectively overcoming losses. The study's findings reveal that implementing this control strategy broadens the fan's operating range and shifts its optimal operating point towards higher flow rates. This improvement is accompanied by a substantial increase in the fan's power density. Furthermore, a notable reduction in sound emissions of approximately 3 dB was recorded, especially when employing the centrifugal fan in the hub. This control strategy also significantly modifies the flow topology downstream of the fan, shifting it from an axial direction to a radial one. [ABSTRACT FROM AUTHOR]

In recent years microstrip patch antennas having minute size is an exciting topic for many researchers and design engineers. In this paper a novel miniaturized microstrip patch antenna for Wi-Fi applications is proposed. The concept of defected ground plane (DGS) is used for achieving miniaturization. The prototype is designed and analyzed by CST Microwave Studio. Low cost FR-4 substrate having thickness of 0.8 mm is used for the design of the antenna. The antenna is having compact size of 16 × 17 mm2. The simulated results demonstrate that the antenna has bandwidth of 2.02% (49 MHz) with -41.46 dB reflection coefficient at resonating frequency. The antenna has bidirectional radiation pattern. The proposed design provides a size reduction of 75.46% in comparison to conventional patch. The proposed antenna is having compact size and is low cost which makes it a suitable candidate for 2.4 GHz Wi-Fi band.

The article deals with frame structures in which the concept战争 / WAR serves as a slot in Chinese media discourse. Given Ukraine’s prolonged state of threat, the study of this concept holds a central position in Ukrainian scholarly research, contrasting with its relatively underexplored status in Chinese discourse. This difference prompts an investigation into the features in Chinese media discourse as the most open type of discourse that exchanges concepts with other discourses. The article identifies the types of basic frames (subject frame, taxonomic or hyponymic frame, associative or, in other words, conceptual metaphor), where the concept战争 / WAR is an integral part. It categorizes the basic frames according to the type of propositions that link the slots and describes the linguistic units of Chinese media discourse that represent the semantics of these frames involving the concept战争 / WAR. The subject frame is represented by 战 争即邪恶 zhànzhēng jí xié’è – WAR IS EVIL, where the second slot gives the first one a strong negative evaluation, being its basic conceptual domain. This is manifested through various lexico-grammatical means: in the negative semantics of the representatives of the concept 战争 / WAR, as well as their collocations. The taxonomic (hyponymic) frame is exemplified by 战争即政治 zhànzhēng jí zhèngzhì – WAR IS POLITICS, where the second concept is superordinate to the subordinate first concept. Additionally, the second concept serves as a means of resolving war, thus striving towards the concept和平 hépíng / PEACE. Finally, the third type of frame structures (associative frames) includes these frames: 战争即赌博 zhànzhēng jí dǔbó – WAR IS A GAME, whose main characteristic is unpredictability; 战争即灾难 zhànzhēng jí zāinàn – WAR IS A DISASTER, specifically fire, which can be further specified as 战争即火焰 zhànzhēng jí huǒyàn – WAR IS FIRE; and 战争即戏剧 zhànzhēng jí xìjù – WAR IS A PLAY.

This research explores the efficacy of a passive control strategy designed to enhance the performance of an axial hollow fan. This investigation uses a dedicated experimental setup to evaluate various aspects of the fan's performance, including characteristics, efficiency, acoustic emissions, and flow topology. The control strategy involves introducing a portion of the main flow into the hollow fan through an upstream opening in the hub. Capitalizing on centrifugal forces, this air portion is injected into the fan's periphery via an axial slot at the rotating shroud ring. Additionally, to refine the previous strategy, a centrifugal fan is incorporated into the hub to assist in directing the flow toward the hollow blades and effectively overcoming losses. The study's findings reveal that implementing this control strategy broadens the fan's operating range and shifts its optimal operating point towards higher flow rates. This improvement is accompanied by a substantial increase in the fan's power density. Furthermore, a notable reduction in sound emissions of approximately 3 dB was recorded, especially when employing the centrifugal fan in the hub. This control strategy also significantly modifies the flow topology downstream of the fan, shifting it from an axial direction to a radial one.

The study is devoted to the explication of the frame LOVE AFFAIR in the lexico-semantic system of the Russian language and speech itself. The research is based on the data from Russian etymological, explanatory dictionaries, dictionaries of synonyms, and modern podcasts. The urgency of the research is determined by the undying interest of scientists to the words that reflect stereotypes of people’s social interaction, which is explained by the importance of looking into ethical categories such as human acts. The lexemes that are examined in the study are selected from dictionaries with the help of the definitional analysis. The method of frame modelling is also used in the study to organize the data into a structure. In order to create a frame model of the act the following procedures are involved: the analysis of the semantics of the words that represent the situation of a love affair, the analysis of the synonyms and the combinability of the words. These procedures help to reconstruct the frame of the object in study. The next step is to verify the frame in modern speech. This paper is the first study of the concept LOVE AFFAIR in modern public communication such as podcasts. The choice of the material is explained by the fact that podcasts look at the most important questions from all angles. The research identifies the most important characteristics of all the elements of the situation «love affair», shows the interrelation of these elements, determines the peculiarities of the explication of the model in the language system and modern speech, marks the prototypical meanings of the structural elements. As a result, the conclusion about semantic broadening of the word affair is made, as well as reinterpretation of traditional negative evaluation of the act «love affair».

Summary A compact flag‐shaped slotted multiple input multiple output (MIMO) antenna is deliberated in the article for triple‐band applications. The flag‐shaped slotted antenna is built with the help of four radiating patches having rectangular slots and disconnected ground structures. The suggested flag‐shaped slotted antenna can operate in the key frequencies of 2.4, 3.5, and 5 GHz. The antenna elements are oriented orthogonally with each other, such that no external decoupling structures are required to provide isolation. The complete size of the four‐element MIMO is 30*30*1.6 mm3. The minimum isolation between the four flag‐shaped slotted elements is −61, −55, and −47 dB in the operating frequency band of 2.3–2.8 GHz, 3.4–3.9 GHz, and 4.5–5.6 GHz, respectively. The simulated and measured results agree with each other, and they have stable radiation and gain. The MIMO performance parameters are measured, and it is noticed that the envelope correlation coefficient is lower than 0.04 and the diversity gain is 9.99 dB in the considered working frequency bands. The proposed flag‐shaped slotted MIMO is appropriate for WLAN, 5G sub‐6 GHz, and ISM wireless applications. [ABSTRACT FROM AUTHOR]

Most communication systems developed for the space industry are employing two passive antennas: one being dedicated to the uplink channel and the other to the downlink channel. Our challenge in this paper is to develop a dual-band antenna operating for both channels. This work presents the dual-band antenna design process and describes its simulated performances measurements and results using CST MWS. The antenna consists of a square patch with four slots around edge, two layers of substrate separated by a ground plane, and a suitable feed network located at the bottom. The design shown has a small footprint of 70 × 70 × 7.012 m m suitable for CubeSat communication system. The designed antenna achieves the following main characteristics: in uplink a bandwidth of 141.6MHz (from 1.9533 to 2.0949GHz), a gain of 7.13dB with a return loss of - 23.62 d B , and an axial ratio of 1.254dB for the 2.034GHz frequency. In the downlink, a bandwidth of 153.3MHz (from 3.1519 to 3.3052GHz), a gain of 7.3dB with a return loss of - 19.18 d B , and an axial ratio 2.649dB for the 3.252GHz frequency. [ABSTRACT FROM AUTHOR]

A miniature Multiple Input Multiple Output (MIMO) Ultrawideband (UWB) antenna with C-band notch is recommended for wireless communications. The radiator is etched on an economical FR4 substrate and is 40 × 21 mm2 in size. The antenna is comprised of a circularly notched rectangular patch embedded with an ellipse and is fed by a 50-Ω microstrip line. To reduce mutual coupling by < −18 dB throughout the whole operational bandwidth of 2.94–11.61 GHz without employing any coupling device, the two radiators are positioned side-by-side with a separation of 0.03 λ0 (λ0 is the wavelength at the lower cutoff frequency of 2.94 GHz). A U-type slit is cut into the patch to produce the band-notch at C-band across 3.63–4.15 GHz. Results from simulation and experiment concludes that the suggested radiator has a wide impedance bandwidth (S11< – 10 dB) and strong mutual coupling (S21 < −18 dB) between 2.94 and 11.61 GHz. Except at the notch frequency of 4 GHz, where the gain is −3.21 dBi, the peak gain and peak radiation efficiency are both 4.21 dBi and more than 82%, respectively. The measured envelope correlation coefficient (ECC) of 0.002, peak diversity gain (DG) of 9.999 dB, and mean effective gain (MEG) of less than −3 dB over operating band, along with the omnidirectional characteristics of the radiator, prove its suitability for use in wireless systems. [ABSTRACT FROM AUTHOR]

Loot boxes (LBs) are microtransactions within video games that offer players the opportunity to acquire virtual items randomly. LBs shared structural and psychological features with gambling, especially slot machines. However, one potential shared feature that has been scarcely explored in LBs, is the level of arousal experienced by players. This study explores changes in electrodermal activity (EDA), heart rate (HR) and respiratory rate (RR) during the opening of LBs in FIFA and during simulated slot machine spin in gamblers (n = 14, M = 19.93 years), LB users (n = 13, M = 19.62 years) and a control group (n = 13, M = 21.92 years). Additionally, the study aimed to compare psychophysiological activation levels produced by both dynamics in each group. Results indicated that both gamblers and LB users showed increased EDA during LB opening and slot machine spins, while HR or RR did not exhibit significant changes. The control group showed increased EDA during the slot machine spin, with no changes during LB opening or in other psychophysiological measures. The comparison between LB opening and slot machine spin revealed similar levels of psychophysiological activation for gamblers and LB users. These findings suggest a potential link between gambling and LBs, which could inform the development of policies for safer gaming environments.

The paper focuses on the comparative study into the effectiveness of film cooling of a flat wall surface by pulsed blowing of secondary airflow through a slot inclined at an angle of 30 deg to the main flow. The impact intensity of pulsation affecting the development of the heat shield was analyzed at different values of the blowing ratio. [ABSTRACT FROM AUTHOR]

В статье рассматриваются особенности актуализации слота «персонаж» как одного из ключевых составных элементов структуры фрейма мифообраза ‘Russia’, формируемого в современных британских и американских новостных текстах. С помощью метода корпусного анализа, описательно-аналитического и дистрибутивно-статистического методов, а также метода контекстуального и когнитивно-прагматического анализа, были выявлены особенности вербализации образа России через слот «персонаж», конструируемого авторами англоязычных новостных сообщений, на примере языковой единицы ‘Putin’ и производных от нее неологизмов, используемых авторами с целью воздействия на сознание и ценностные установки реципиентов новостного сообщения. На основе рассмотренных новостных текстов заключается, что актуализация образа президента России в современных англоязычных новостных текстах посредством слота фрейма ‘Russia’ носит мифологизированный характер и реализует скрытую интенцию авторов, использующих фрейминг как способ языкового конструирования образа, и, в частности, неологизмы-дериваты, реализуя таким образом прагматический эффект новостного сообщения и способствуя мифологизации образа личности.

Floriography is part of many cultures and provides an effective characterization means for a particular linguistic culture. The frame analysis method is a popular tool in phraseology, but it has never been applied to phraseological units with the flowers component. The study examined phraseological units with the flowers component in Russian, English, and Chinese in order to define their role in the corresponding linguistic worldviews. The frame organization analysis made it possible to identify the way these languages categorize reality. Phraseological units with flowers are more typical of Chinese and English; they are less typical of the Russian linguistic culture as a result of the harsh climatic conditions and the farming traditions. In this research, the frame analysis hinted at similar cognitive processes in all the three linguistic cultures, which was manifested as common subframes at all levels. The main subframes included characteristics of the subject, action aimed at the subject, qualitative assessment of reality, and evaluative characteristics of the action. In addition, flower names described different human qualities, characterized an ongoing event, and evaluated actions performed by the subject. Differences were registered at the slot level as a partially overlapping list of qualities, assessments, characteristics, and actions, which reflected the specifics of each national worldview. The results can facilitate intercultural communication for Russian, English, and Chinese speakers.

In the article, the effect of the surface on the strength of the corner joint on the window was analyzed. The corner joint on the window is made in the variant with double and triple dowel and slot using PVaC adhesive. Samples were made from pine tree (Pinus Nigra). For research purposes, a special holder was made for the samples to enable testing according to the EN514:2018 standard method. The aim of the work is to determine the influence of the connection element on the strength of the corner joint of the window when using PVaC glue. The samples were divided into 2 groups of 30 samples each, depending on the number of dowels. The standard methods of statistical analysis were used. The test showed that the connection with triple dowel and slot has higher breaking strength values compared to double dowel and slot.

Nowadays, axial fans participate in the most important areas of industry and research, including aviation, navy, wind tunnels, cooling towers, and even automobiles. Thus, more emphasis has been placed on improving their aerodynamic performances. It is important to notice that the parameters involved in designing a fan are mainly concerned with aeraulic power, torque and efficiency. This study investigates the utilization of flow control techniques to improve performances of an axial fan equipped with hollow blades, shroud, and hub. These features grant the fan crucial characteristics, namely, its lightweight and facilitate the blowing action by taking advantage on its hollow parts. The fan's performance is evaluated using a steady RANS numerical model with a k-ω SST turbulence closure, which was validated with experimental data. An active control air blowing through a slot was introduced with various positions and dimensions. The results demonstrate a significant improvement in the fan's performance, with an up to 56% increase in aeraulic power gain, accompanied by changes in the overall flow topology, noticed by closely analyzing the flow structure near the tip clearance.

Summary: A small size, dual‐band and dual‐sense monopole antenna is proposed to improve the axial ratio bandwidth (ARBW). The proposed antenna is considered on a low‐cost lossy FR4 substrate with parasitic strips (PSs) and partial ground plane of half guided wavelength dimensions. The dimension of the antenna in terms of wavelength is 0.27λ0×0.29λ0×0.02λ0, where λ0 is the wavelength at the lowest resonant frequency. The circularly polarized (CP) mode is created for strong orthogonal electric fields EX and EY. The obtained phase difference (PD) between two electric fields EX and EY is varied from 86° to 96° under ARBW. The achieved ARBW is 3.68–3.8 GHz, 4.84–12.58 GHz, and impedance bandwidth (IBW) is 3.51–3.82 GHz and 4.28–15 GHz. The applications of the proposed antenna are International Telecommunication Union (ITU) for 5G, C‐band IEEE 802.11a wireless local area network (WLAN) at 5 GHz (5.15–5.825 GHz) and X‐band wireless systems. [ABSTRACT FROM AUTHOR]

Nowadays, axial fans participate in the most important areas of industry and research, including aviation, navy, wind tunnels, cooling towers, and even automobiles. Thus, more emphasis has been placed on improving their aerodynamic performances. It is important to notice that the parameters involved in designing a fan are mainly concerned with aeraulic power, torque and efficiency. This study investigates the utilization of flow control techniques to improve performances of an axial fan equipped with hollow blades, shroud, and hub. These features grant the fan crucial characteristics, namely, its lightweight and facilitate the blowing action by taking advantage on its hollow parts. The fan's performance is evaluated using a steady RANS numerical model with a k-ω SST turbulence closure, which was validated with experimental data. An active control air blowing through a slot was introduced with various positions and dimensions. The results demonstrate a significant improvement in the fan's performance, with an up to 56% increase in aeraulic power gain, accompanied by changes in the overall flow topology, noticed by closely analyzing the flow structure near the tip clearance. [ABSTRACT FROM AUTHOR]

During the operation of certain structures, two questions arise: about the stress-strain state (SSS) at a point and in its neighborhood on the surface of the object under study and in its bulk, and about the remaining material strength in the considered area. The values of stresses and strains not at a point, but in a neighborhood, make it possible to use the results of the proposed research to test existing numerical and analytical calculation schemes, to find the direction of growth or decrease of the quantities under consideration, and to predict catastrophic events. It is proposed to assess the state of the material using classical formulations and methods of solid mechanics, which guarantee the existence and uniqueness of the solution and continuous dependence on the input data. To determine the SSS of the material in the neighborhood of the point, we start with the full unload of the latter in order to determine the unloading displacements at the boundary. The SSS within the area, including stresses at the boundary, is found from the known boundary displacements. When studying the SSS inside the body, it is proposed to install elongated reference elements with their ends reaching the surface. To measure unloading displacements, the existing optical, mechanical, and tensometric systems are used. The uniqueness of the proposed approach is in considering not only radial displacements, but also tangential ones. The aim of the work is experimental and analytical determination of the SSS at any point of the structure and at any time of its non-stop operation. [ABSTRACT FROM AUTHOR]

Asynchronous motors have become part of everyday life. There are various types and shapes, and they are found in all machines that are used to process materials. Recently, these motors have been mainly controlled by frequency regulators, that is, electronics that extract the desired performance from them. Not infrequently, the dimensions of these engines are reduced to the extreme, for the reason that they could fit into the requirements of the machines. As such, they are subject to breakdowns, and very often we are in a situation where we need a lot of time to procure and replace them. This causes very high costs in production, so in order to reduce them, winding of asynchronous motors is resorted to. In this context, the goal of the work was to examine whether rewinding, which was done according to all technical principles, affects the quality of the motor, that is, whether such a motor will still be able to perform its intended functions. The main idea was to accurately calculate the required wire cross-section and replace that calculated wire cross-section with two other wire cross-sections that are close to the calculated wire cross-section. The replacement was made for the reason that this most often happens in rewinding centers where they do not have the calculated cross-section of the wire, but replace the calculated cross-section with the cross-sections they have on hand. After this, we recorded the loads of individual parts of the engine using a thermal imaging camera and made the necessary conclusions. [ABSTRACT FROM AUTHOR]

A slotted microstrip patch antenna for fifth‐generation (5G) mobile applications is presented in this paper. The proposed antenna addresses the intrinsic narrow bandwidth of patch antennas by introducing rectangular slots in the form of a disjointed H‐slot to broaden the bandwidth. The patch design and the slots introduce two extra resonances to broaden the bandwidth of the antenna. An impedance bandwidth of 26.6% from 24.95 to 32.6 GHz was achieved. A measured peak gain of 9.44 dBi was also achieved with a minimum half‐power beamwidth of 36° over the entire bandwidth. The proposed slotted patch antenna is implemented on a 44.6 mm × 26.3 mm × 0.8 mm RT5880 Printed Circuit Board. [ABSTRACT FROM AUTHOR]

In this letter, a compact circular cavity‐backed, circularly polarized substrate integrated waveguide (SIW) multiband antenna is proposed. In the outer circular cavity, an array of two periodic metal slots, tilted at an angle, resonate at 25.32, 26.44, and 28.83 GHz, and the inner circular cavity's periodic slots radiate at 28.01 GHz. Two concentric SIW cavities are structured in such a distinct manner that no loss due to leakage takes place thus, achieving a maximum isolation of −43.8 dB at 28.83 GHz. The miniaturized antenna has dimensions of 2.2λo × 2.2λo × 0.1λo where λo is the operating wavelength. It achieves a maximum gain of 9.1 dBi at 26.44 GHz, and VSWR < 2 is achieved at all frequency bands. The antenna is circularly polarized at 26.44 and 28.01 GHz as well. The design results are plotted in the Ansys high‐frequency structure simulator version EM19.2 tool. The proposed antenna is fabricated and tested using an Anritsu Vector Network Analyzer version v4.0 with an anechoic chamber setup. [ABSTRACT FROM AUTHOR]

In this article, a triple-band patch antenna using a circular patch microstrip antenna is constructed with a low-profile patch antenna using a 1.5 mm thick FR4 substrate (εr= 4.3). As mobile devices like smartphones and laptops become more common, the usage of tiny, triple-band antennas has also become more common. The objective of this research is to design a circular patch antenna with a 3–11 GHz dipole-like radiation pattern, which may be used for industrial, scientific, and medical reasons. For the suggested tripleband antenna design, the slotted radiator with six arches and the reduction of the ground plane are among the components. In addition, the standard 50 Ω RF transmission line stimulates the patch antenna; this transmission line is attached to the microstrip line by an impedance-compliant SMA connection. Data from the experiments are obtained, evaluated, and compared; to the patch's surface current distributions, gain, and radiation patterns. According to the measurements, S11 has an impedance bandwidth in the 5.5 GHz band of less than -10 dB, 6.6 GHz band, and 10.4 GHz band at all frequencies. The superb radiation pattern performance, relatively consistent gain throughout the bands, and practical bandwidths of this antenna make it a good choice for C-band and dual X-band applications. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Ablai Khan KazUIRandWL: Series 'Philological sciences' is the property of Kazakh Ablai Khan University of International Relations & World Languages and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Influence of streamwise slots with the orientation angle φ = 0 and various depths h (corresponding Reynolds number Reh = 0–2000) on the stability of the supersonic (M = 2) flat-plate boundary layer with relation to natural disturbances of the first (vorticity) instability mode driving laminar-turbulent transition was investigated experimentally. Experiments shown that such kind of disturbances can be stabilized by small-depth streamwise slots, wherein the maximum stabilization occurs at the Reynolds number (based on the slot depth) of about Reh ≈ 1000. [ABSTRACT FROM AUTHOR]

A dual frequency band and a triple frequency band rectangular-shaped microstrip antenna will be discussed in this research study. The proposed antennas' microstrip patch has slots that have been loaded to provide them dual frequency band and triple frequency band features. The proposed antenna-(1) provides two resonance frequencies of 3.47 GHz and 4.78 GHz. At 3.47 GHz and 4.78 GHz, respectively, the simulated peak gains are 3.65 dBi and 2.8 dBi. The proposed antenna-(2) provides three resonant frequencies of 2.1 GHz, 3.26 GHz, and 5.48 GHz with simulated peak gains of 4.05 dBi, 1.55 dBi, and 1.53 dBi respectively. The proposed antenna-(1) has obtained a compactness of 51.10% in terms of its first resonance frequency, whereas the proposed antenna-(2) has acquired a compactness of 82.06% in terms of its first resonance frequency. At the two suggested antennas' various resonate frequencies, the radiation patterns (E and H plane) are good. High Frequency Structure Simulator (HFSS) software was used to construct and model the suggested antennas, and the simulated results (reflection coefficient (dB)), peak gain, and normalized (E-H plane radiation patterns) are presented here. There are a variety of wirelessly efficient applications that could be benefitted from the suggested antennas. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Faculty of Forestry / Glasnik Šumarskog Fakulteta is the property of University of Belgrade, Faculty of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since the Wright Brothers’ first flight in 1903, extensive research has been dedicated to improving the aerodynamic performance of aircraft. This study investigates the effect of two distinct wing geometric modifications on airfoil performance at high angles of attack (AOAs). These two modifications are slot, specifically the NACA 4412 with only a slot, and groove, specifically the NACA 4412 with both a slot and a groove. The investigation combines numerical simulation using ANSYS fluent with experimental evaluations conducted in the VDAS AF1300 subsonic wind tunnel. Since turbulent airflow often results in early stall, the primary objective of this research is to delay the stall angle of the normal NACA 4412 airfoil by mitigating local separation zones, and boundary layer transitions. Numerical simulations are performed at airspeeds of 20 m/s and 43.9 m/s, while experimental investigations are conducted at a speed of 20 m/s. The results indicate that both modified airfoils have higher lift-to-drag ratio than the normal airfoil at high AOAs. Specifically, the NACA 4412 airfoil with only a slot demonstrates the highest lift-to-drag ratio among the modified airfoils at high AOAs. Moreover, the NACA 4412 airfoil equipped with a slot and a groove demonstrates the highest stall angle, measured at 18°, compared to the normal NACA 4412 airfoil with a stall angle of 14°. At high AOA, the NACA 4412 airfoil with a slot generates a nearly 35 % higher lift coefficient than the normal NACA 4412 airfoil, while the NACA 4412 with a slot and a groove achieves almost a 16 % higher lift coefficient than the normal NACA 4412 airfoil.

Introduction. In the spring of 2020, the pandemic of coronavirus was announced in the world – the disease caused by the new type of coronavirus SARS-COV-2. In connection with the progressive psychoemotional stress in society in the literature and the media, attempts are made in a simple and affordable form to explain the causes of this disease and prevention methods. Despite the fact that the children's contingent was the least susceptible to the disease, this topic was widely covered in children's books, posters and brochures. The purpose of this article, therefore, is to analyze and study various methods of verbalizing the renewal of knowledge about coronavirus infection through lexical units. The article describes the results of the analysis of the concept of “coronavirus”, reflecting the “childish” vision of the disease.Methodology and sources. To create an idea of the concept of “Coronavirus”, it is required to conduct a framework analysis and build concepts of concepts that dominate generally in the discourse. For this, it is necessary to conduct a case analysis of children's texts, conceptual analysis and method of modeling using the theory of cognitive metaphor. Also, the compilation of frames will need to conduct definition, etymological, component and contextual analyzes.Results and discussion. Within the framework of this article, the role of metaphor as the main mechanism for representing information about the disease and its prevention is presented. As a result of the study, strategies for the verbalization of knowledge about coronavirus infection were revealed, contributing to training and socializationConclusion. The significance of the presented work is determined by the possibility of using the results of the study in theoretical and practical courses in cognitive linguistics, discourse theory, text linguistics and metaphorology. In addition, the results of the study can be used in theoretical and practical medical activity to optimize the connection in the field of pediatrics.

Antenna design is usually done on FR4 substrates, since they have a dielectric constant of 4.4, and a loss tangent of 0.02. The proposed microstrip patch antenna operates at 28 GHz and incorporates substrate-integrated waveguides (SIW) in a 0.8 mm thick FR4 substrate into the design to increase bandwidth performance so that the 5G network can function reliably. In comparison with conventional patch antennas, substrate-integrated waveguides bear the advantage of being able to shift to a frequency of 29 GHz, therefore resulting in a more effective antenna. A slot of eyebolt shape has been added to the patch to increase antenna gain. The design was simulated with HFSS software, and it was able to attain a maximum bandwidth of 8 GHz (28%), a gain of 5.5 dB, and a minimal return loss of −38 dB. The VSWR of this antenna is 1.02, which indicates good impedance matching, and a high efficiency of 87% has been achieved as a result. This is a low-profile antenna that combines enhanced bandwidth with the ability to be mounted at the edge of a device, making it an ideal choice for the use of 5G technology to enable machine-to-machine communication.