Propagation Conditions Research Articles

Empirical Performance Evaluation of 5G Millimeter Wave System for Industrial-Use Cases in Real Production Environment

Wireless communication plays an important role in the digitization of industries. A 5G cellular communication system enables several industrial automation use cases. Fifth-generation deployments in industrial use cases have mainly been carried out in the sub-7 GHz frequency range. In this work, we empirically study 5G system performance in the millimeter wavelength (mmW) range for industrial use cases: additive manufacturing processes and precision manufacturing robotics. We carry out an experimental performance evaluation of a commercially available non-public 5G mmW system to assess its latency, reliability and throughput for uplink and downlink data traffic in a real industrial environment. We also investigate the impact of various 5G configurations on 5G performance characteristics with insights from the baseband log information as well as unidirectional latency measurements. Our empirical results indicate that 5G mmW system can achieve low latency with high reliability in both one-way traffic directions. The throughput is observed to be high for line-of-sight (LOS) scenarios, making the use of the 5G mmW system appealing especially for data rate-intensive and time-critical industrial use cases. We also observe that industrial environments with lots of metal and reflective surfaces provide favorable propagation conditions for non-LOS transmissions. Our results indicate that static industrial use cases with low mobility can leverage the performance benefits of 5G mmW systems.

БИОХИМИЯ И БИОЛОГИЯ ОБРАЗЦОВ ЧЕТЫРЕХ ВИДОВ ЛУКА ЧЕРЕМШИ В КУЛЬТУРЕ В РЕСПУБЛИКЕ БАШКОРТОСТАН

The pape presents the data of a study of 6 samples of wild garlic onion, which were carried out in the South Ural Botanical Garden-Institute of the Ural Federal Research Center of the Russian Academy of Sciences in 2018–2022, (Bashkir Cis-Urals, northern forest-steppe). Plantings of A. ochotense accessions (Syktyvkar and Irkutsk) are located in an open sunny area, plantings of the Syktyvkar accession A. victorialis are located in an open area and in the shade, plantings of A. microdictyon, A. ursinum and A. victorialis (VILAR) are in shade conditions. Biochemical analyzes were performed at the Bashkirsky Agrochemical Service Center according to generally accepted methods. The study of phenology, morphological and reproductive parameters was carried out according to standard methods recommended for botanical gardens. Studies showed that the greatest accumulation of ascorbic acid was noted in the victorious onion (Syktyvkar, 62.91 mg%), the lowest accumulation was in fine-meshed onion (Bashkortostan, 48.74 mg%), based on fresh weight. Victorious onion samples (Irkutsk, VILAR) differed in the maximum content of the following most important biologically active substances: carotene (1.68–2.89 mg/100 g), dry matter (22.81–25.23 %), crude fat (1 .04–1.13 %), protein (3.69–4.38 %), nitrogen (0.59–0.70 %), sugar (4.34–4.79 %), starch (0.41–0.95 %), potassium (0.36–0.4 %), phosphorus (0.11–0.12 %), calcium (0.08-0.09 %) and copper (1.09–1 .65 mg/kg) (based on fresh weight). The content of the minimum amount of the following biologically active substances was noted in bear onion (VILAR): dry matter (10.91 %), crude fat (0.50 %), protein (1.81 %), nitrogen (0.29 %), sugar (2.20 %). In the conditions of the sharply continental climate of the Republic of Bashkortostan, wild garlic onion samples are winter hardy, not damaged by pests and diseases. Seed productivity is satisfactory, vegetative propagation and general condition is good. Out of six samples of four types of wild garlic onion, the samples of A. victorialis have the highest indicators in terms of the content of biologically active substances. The studied samples of wild garlic are promising plants for cultivation in the Republic of Bashkortostan, as well as in the South Ural Region. This allows us to recommend them for expanding the range of useful (vitamin) and ornamental plants.

Analysis of probability density functions for aperture-averaged fluctuations of laser radiation power for extended range of atmospheric propagation conditions

Analysis of probability density functions for aperture-averaged fluctuations of laser radiation power for extended range of atmospheric propagation conditions

Наземные наблюдения ОНЧ аврорального хисса в обсерваториях «Ловозеро» и «Баренцбург»

The paper presents the results of the analysis of auroral hiss bursts, measured at Lovozero and Barentsburg observatories. These points are located on close geomagnetic meridians in the auroral and circumpolar zones. The auroral hiss bursts occur first in the auroral zone at Lovozero Observatory. Then, they fade out smoothly and occur in the circumpolar zone at Barentsburg Observatory. These events are observed when geomagnetic activity and the source of phase scintillation of GPS signals move from auroral to circumpolar latitudes. Analysis of magnetic field polarization and arrival angles of the bursts has shown that the area on the Earth surface, illuminated by hiss bursts, arose at auroral latitudes near Lovozero Observatory, and then moved to higher latitudes. Since propagation of the hiss to the ground and occurrence of GPS signal scintillation requires the presence of electron density irregularities of similar scales in the ionosphere, we assume that the same irregularities could cause both phenomena. A possible cause of their occurrence is the development of current-convective and (or) drift instability in the ionosphere caused by the development of field-aligned currents. Their development is indicated by the simultaneous recording of Pi1B pulsations. The results show that the termination of hiss at auroral latitudes may be caused by a shift of the geomagnetic disturbance region to high latitudes, rather than changes of wave propagation conditions in the ionosphere.

Ground-based observations of the VLF auroral hiss at Lovozero and Barentsburg observatories

The paper presents the results of the analysis of auroral hiss bursts, measured at Lovozero and Barentsburg observatories. These points are located on close geomagnetic meridians in the auroral and circumpolar zones. The auroral hiss bursts occur first in the auroral zone at Lovozero Observatory. Then, they fade out smoothly and occur in the circumpolar zone at Barentsburg Observatory. These events are observed when geomagnetic activity and the source of phase scintillation of GPS signals move from auroral to circumpolar latitudes. Analysis of magnetic field polarization and arrival angles of the bursts has shown that the area on the Earth surface, illuminated by hiss bursts, arose at auroral latitudes near Lovozero Observatory, and then moved to higher latitudes. Since propagation of the hiss to the ground and occurrence of GPS signal scintillation requires the presence of electron density irregularities of similar scales in the ionosphere, we assume that the same irregularities could cause both phenomena. A possible cause of their occurrence is the development of current-convective and (or) drift instability in the ionosphere caused by the development of field-aligned currents. Their development is indicated by the simultaneous recording of Pi1B pulsations. The results show that the termination of hiss at auroral latitudes may be caused by a shift of the geomagnetic disturbance region to high latitudes, rather than changes of wave propagation conditions in the ionosphere.

Method of determining the coordinates of a low altitude object under the conditions of using several radio signals.

Currently, in large cities, there is a steady tendency to increase the spatial density of telecommunication systems. The saturation of the radio spectrum with analog and digital systems used to solve the problems of radio communication and television allows to improve the technologies of semi-active radar detection and determination of the coordinates of a low-altitude object on their basis. Conducting radar surveillance using non-radar radar transmitters is often called semi-active radar using extraneous or parasitic radiation sources. The advantages of such systems are the minimization of deployment costs, low operating energy costs, low probability of malfunctioning, stealth of the fact of operation, environmental friendliness, and the absence of requirements for the allocation of radio frequency resources. Relatively high heights of antennas of communications and television transmitters with the existing radiated power create favorable conditions for detecting low-altitude objects. Digital signals of modern telecommunication systems have a spectrum width that provides acceptable resolution and accuracy of measuring the total distance and angular coordinates [20; 21]. In the general case, systems of this type are a multi-position system consisting of one or more radiation sources and one or more receiving positions spread in space [22; 23]. The paper gives a general description of the proposed method of determining the coordinates of an aerial object at low altitude under the conditions of propagation of several beams of radio signals. The method and its technical solution capable of determining the coordinates of an unauthorized low-altitude object under the conditions of the existence of several rays of radio signal propagation are defined, and the algorithm of its operation necessary for the technical implementation of the proposed method is presented. The paper considers options for determining the coordinates of aerial objects with different composition of primary coordinate measurements and the number of receiving points. The accuracy of determining the location of the object for multi-position radio systems of this type was evaluated under the conditions of the existence of several beams of radio signal propagation in the developed model, taking into account the number of received signals and their measurement errors.

Magma Chamber Response to Ice Unloading: Applications to Volcanism in the West Antarctic Rift System.

Volcanic activity has been shown to affect Earth's climate in a myriad of ways. One such example is that eruptions proximate to surface ice will promote ice melting. In turn, the crustal unloading associated with melting an ice sheet affects the internal dynamics of the underlying magma plumbing system. Geochronologic data from the Andes over the last two glacial cycles suggest that glaciation and volcanism may interact via a positive feedback loop. At present, accurate sea-level predictions hinge on our ability to forecast the stability of the West Antarctic Ice Sheet, and thus require consideration of two-way subglacial volcano-deglaciation processes. The West Antarctic Ice Sheet is particularly vulnerable to collapse, yet its position atop an active volcanic rift is seldom considered. Ice unloading deepens the zone of melting and alters the crustal stress field, impacting conditions for dike initiation, propagation, and arrest. However, the consequences for internal magma chamber dynamics and long-term eruption behavior remain elusive. Given that unloading-triggered volcanism in West Antarctica may contribute to the uncertainty of ice loss projections, we adapt a previously published thermomechanical magma chamber model and simulate a shrinking ice load through a prescribed lithostatic pressure decrease. We investigate the impacts of varying unloading scenarios on magma volatile partitioning and eruptive trajectory. Considering the removal of km-thick ice sheets, we demonstrate that the rate of unloading influences the cumulative mass erupted and consequently the heat released into the ice. These findings provide fundamental insights into the complex volcano-ice interactions in West Antarctica and other subglacial volcanic settings.

Shallow water communication with an object buried in bottom sediments

Underwater acoustic communications (UAC) in shallow water applications is a very difficult task. This task becomes even more difficult when there is a need to ensure reliable communication with an object buried in bottom sediments. The article presents a simulation of an acoustic transmission channel in conditions of strong multi-path propagation to an object buried in bottom sediments. The impulse response method was used, supported by a technique derived from the ray tracing image source method. Simulation results are presented for both narrowband and broadband signals with LFM frequency modulation. Based on the simulation, the conditions that should be met by the transmission signals to ensure correct communication were determined. Examples of data transmission to an object buried in bottom sediments in a simulated shallow channel with multi-path propagation were also presented.

Investigation of Tropospheric Radio Refractivity and other Relevant Parameters across Some Selected Locations in the Sahelian Region of Nigeria

The troposphere's internal processes are complex and exhibit nonlinear trends, which have a significant impact on the transmission and reception of high-quality signals worldwide. This study used measured monthly climatic data of temperature, relative humidity, and atmospheric pressure for Maiduguri and Sokoto from the National Aeronautic and Space Administration (NASA) over a forty-two-years period (1981 to 2022) to estimate the seasonal tropospheric radio refractivity and examine its variations with other meteorological parameters and refractive index. The refractivity gradiant, effective earth radius, and percentage contribution of the dry and wet term radio refractivity were also examined. According to the results, radio refractivity was found to be highest at the two locations during the rainy season and lowest during the dry season. In Maiduguri, during the rainy season and dry seasons are 361.4837 N-units in August, 272.4506 N-units in March while for Sokoto are 366.7093 N-units in August, 277.1162 N-units in February. For Maiduguri and Sokoto, the wet term (Nwet) contributes to the significant variation with 19.9753 % and 21.1831%, respectively, while the dry term (Ndry) contributes 80.0247 % and 78.8169 % to the total value of radio refractivity. The average refractivity gradients in the studied locations were found to be -42.3746 and -42.3928 N-units/km. Furthermore, it was discovered that Maiduguri and Sokoto had average effective earth radiuses (k-factors) of 1.3697 and 1.3698, respectively. These values implied super refraction propagation condition.

Chuprov invariant for vector-scalar fields of multipole sources in a shallow sea

A computational and theoretical study of the properties of the well-known waveguide invariant S.D. Chuprova (IC) was carried out in a plane-parallel Pekeris waveguide. Unlike earlier works, in which predominantly non-directional (monopole) sources were used as a source, and sound pressure fields (scalar fields) were studied, in this work not only scalar, but also vector fields formed in the waveguide by directional - combined multipole sources with directivity in both horizontal and vertical planes. A differential equation has been obtained that makes it possible to fairly accurately calculate the IC values under different conditions of signal propagation and different depths of sources and receivers. This makes it possible, in a simpler way than “full computer modeling,” to predict the invariance (stability) of the IC when varying both the hydrophysical conditions in the waveguide and the geometry of the experiment. It is shown that the directionality of sources in the horizontal plane has virtually no effect on the properties of the IC, and the directionality in the vertical plane leads to a shift in the fan structure of the signal amplitude fields, but has little effect on the IC values. The properties of the fan structure change in a similar way when using vertical projections of the oscillatory velocity vector - despite the fact that another analytical relation, different from scalar fields, is used to calculate the IC, the IC value is close to (+1) at all frequencies and distances, except those at which new modes or dislocations arise. At these frequencies and in these zones, alternating emissions with different signs and magnitudes occur. It is concluded that the stability of IC allows the application of signal processing algorithms developed for scalar fields and non-directional sources to vector-scalar fields generated, including using directional sources.

Features of propagation in the atmosphere of nonlinear acoustic disturbances from pulse sources

The features of the propagation of nonlinear pulsed acoustic disturbances in the atmosphere are considered. Data are presented on the experimental observation of the formation of a shock front and the transition of a shock wave into a low-intensity acoustic wave with transformation of the pulse shape and expansion of the front at distances of more than 1000 km under conditions of both spherical and cylindrical propagation. The influence of Kelvin-Helmholtz instability during rapid gas compression on the formation of the shock front structure is discussed. Under atmospheric conditions, such instability significantly affects dissipative processes in the air and forms the front of a nonlinear wave.

Influence of density variations of ionosphere plasma on the conditions of electromagnetic whistler waves propagation in the ionosphere

Background. Plasma density variations caused by infrasonic wave can significantly affect conditions of propagation and reflection of whistler electromagnetic wave incident on the ionosphere from above. Aim. In that work, relationship between the coefficient of wave energy reflection from ionosphere, electromagnetic wave field near the ground surface and parameters of infrasonic wave are studied. Methods. The collocation method for solving the boundary problem for a plane-layered ionosphere and the perturbation theory method are used to find the electromagnetic wave field. Results. The greatest modulation of the reflection coefficient is associated with density perturbations at altitudes 80–110 km where whistler decay increases by an order of magnitude at the local altitude region (less than 15–20 km). In that case, the reflection coefficient variation can achieve 40 %. Conclusion. The results obtained are important for understanding the interconnection of magnetosphere radiation processes of different nature. The study of the modulation of coefficient of whistler reflection from the ionosphere is relevant for explaining the operation modes of a plasma magnetospheric maser.

Radiation and thermal embrittlement of RPV steels: the links of embrittlement mechanisms, fracture modes and microcrack nucleation and propagation properties. Part 1. Strategy, program and methods of experimental and numerical studies

Further development of local approach models is considered from viewpoint of links of local brittle fracture properties with embrittlement mechanisms and fracture modes for RPV steels. Strategy and program of experimental and numerical investigations have been developed that allows one to find how various embrittlement mechanisms and fracture modes are connected with the conditions of nucleation and propagation of microcracks resulting in brittle fracture of RPV steels. The experimental and numerical investigations are performed for 2Cr-Ni-Mo-V steel and A533 steel used for RPVs of WWER and PWR types. RPV steels are studied in the following states: (1) initial (as-produced); (2) thermally embrittled by a hardening mechanism; (3) thermally embrittled by a non-hardening mechanism; 4) irradiated. Experimental studies include testing specimens of different geometry (smooth and notched round bars, and cracked compact tension specimens), which allows us to obtain characteristics of brittle fracture under various stress triaxialities. Numerical studies performed with the probabilistic brittle fracture model Prometey aim to obtain the brittle fracture properties on micro- and macroscales for all the investigated states of the materials.Part 1 of the paper presents information concerning the investigated materials, the used procedures and methods. Part 2 gives the test results of smooth round bars of the investigated materials in various states and the stress-strain curves determined over wide temperature range. The experimental results for various specimens from the investigated steels in various states are represented and compared with the results predicted with the Prometey model in Part 3.

Enhanced Fatigue Crack Detection in Complex Structure with Large Cutout Using Nonlinear Lamb Wave.

The large cutout structure is a key component in the bottom skin of an airplane wing, and is susceptible to developing fatigue cracks under service loads. Early fatigue crack detection is crucial to ensure structural safety and reduce maintenance costs. Nonlinear Lamb wave techniques show significant potential in microcrack monitoring. However, nonlinear components are often relatively weak. In addition, a large cutout structure introduces complex boundary conditions for Lamb wave propagation, making nonlinear Lamb wave monitoring more challenging. This article proposes an integrated data processing method, combining phase inversion with continuous wavelet transform (CWT) to enhance crack detection in complex structures, with phase-velocity desynchronization adopted to suppress the material nonlinearity. Experiments on a large cutout aluminum alloy plate with thickness variations were conducted to validate the proposed method, and the results demonstrated its effectiveness in detecting fatigue cracks. Furthermore, this study found that nonlinear components are more effective than linear components in monitoring closed cracks.

Experimental verification of the variability of amplitude modulation (AM) from wind turbines in relation to its assessment for annoyance

The analysis of the influence of amplitude modulation (AM) on the annoyance of noise generated by wind turbines (WT) is still the subject of numerous studies. However, there is still a lack of widely accepted quantitative methods that would determine the degree of influence of modulation phenomena on noise perception. The study analyzed the variability of the depth of AM over time within different frequency-ranges. The research was based on long-term measurements at selected measurement locations. Long-term measurement ensured consideration of diverse propagation conditions. The collected data were segmented into time intervals, which included basic AM parameters - depth, modulation frequency, and frequency band in which the AM was observed, as well as wind speed and direction. Statistical analysis of the gathered dataset was used to assess the regularity of distinguished AM parameters in correlation with WT noise energy values and recorded non-acoustic parameters. A significant variability of AM depth was observed depending on the frequency band, masking level, and position relative to the wind direction. By adopting a criterion for assessing the annoyance of WT noise (according to AMWG) with a threshold depth of AM not less than 2 dB, it was noticed in over 30% of the analyzed intervals.

Modelling the effects of a random medium on direct and reflected sound signals from a moving source

Randomnesses in acoustic propagation conditions affect the signal at a receiver placed at a distance from the source. Without any reflecting surface the random medium causes fluctuations in amplitude and phase of the received signal. In the presence of a wave reflecting surface, a version of the signal with other fluctuations is added at the receiver, with some amount of correlation between the direct signal and the reflected signal. A method is presented that in a single approach includes the random fluctuations of the received signals and the decorrelation effect for signal pairs. Numerical examples are calculated and validated in terms of mutual coherence functions by comparison with analytical solutions for different conditions of atmospheric turbulence. Exemplifying sounds with different source signals are produced for a moving source.

Modeling of a moving point source in inhomogeneous and turbulent media - Application to aircraft noise

Engineering solutions for the modeling of aircraft noise often rely on simplified approaches that consider quasi-static sources and homogenous propagation conditions. These hypothesis may lead to significant inaccuracies on sound pressure level predictions in certain configurations, especially for source traveling at high mach number and at several hundred meters from the receiver. In order to overcome these limitations, an efficient numerical model based on the coupling of a heuristic formulation and a ray-tracing model is proposed. The modeling takes into account source motion effect (Doppler effect and convective amplification), as well as the sound propagation phenomena in inhomogeneous media (waves refraction and scattering by atmospheric turbulence). Several case study related to aircraft noise are presented, for which wind and temperature profiles correspond to experimental measurements. The influence of atmospheric turbulence for such configuration is finally discussed. This work is part of the program MAMBO (Advanced methods for engine and aicraft noise modelling" coordinated by Airbus SAS and supported by the Direction Générale de l'Aviation Civile (DGAC).

On the possibility of long‐distance transmission of OAM beam in rectangular tunnels

AbstractThis letter explores the possibility of long‐distance transmission of an orbital angular momentum (OAM) beam through rectangular tunnels. Theoretical analysis reveals that the OAM beam propagating in the tunnel with square cross section fulfills the conditions for axial propagation and exhibits azimuth symmetry. In comparison with free‐space OAM generation, we draw the conclusion that long‐distance transmission of OAM beams is achievable in the tunnels with square cross section. The validity of our conclusion is further substantiated through numerical experiments. Simulation results demonstrate that the first‐order OAM beam radiated by a uniform circular antenna array exhibits favorable helical phase distribution and the circular symmetry of the amplitude distribution in the tunnel beyond the Rayleigh distance. However, these characteristics degrade with increasing mode order and propagation distance, because the increase of high‐order OAM beam divergence angle and propagation distance will exacerbate the impact of multipath effects in the tunnel environment.

Comparative study of the propagation and plaque titration conditions for human coronavirus OC43 as a surrogate for SARS-CoV-2.

The ongoing COVID-19 pandemic is threatening human health globally. The development of effective drugs and vaccines against SARS-CoV-2 is hindered by the limited access to high-biosafety-level facilities. Although human coronavirus (HCoV) OC43, a low-pathogenic endemic human coronavirus, has been used as a surrogate virus for SARS-CoV-2 research, a standard technique for HCoV-OC43 culture and plaque titration has not been established. Our objective was to establish optimized culture and titration protocols for HCoV-OC43. The growth kinetics and permissibility to HCoV-OC43 infection of seven different cell lines were examined concurrently at two different temperatures, 33°C and 37°C. Cell lines exhibiting a cytopathic effect (CPE) were selected for plaque titration. No significant difference in the rate of cell growth was observed at the two temperatures tested. Interestingly, HCoV-OC43 was found not to be a high-temperature-sensitive virus, since it grew well at 37°C. Although RD, LLC-MK2, MRC-5, and HCT-8 cell lines supported virus growth with an obvious cytopathic effect and a high yield of virus after two days of infection, only RD cells were suitable for producing countable plaques. The incubation of the cells with 1.2% low-viscosity Avicel as an overlay medium at 37°C for 4 days appeared to promote clearer and sharper plaque morphology. However, further optimization of the plaque titration protocol is still required due to the continued observation of plaque size variation and hazy zones. We propose a cost-effective protocol for HCoV-OC43 culture and plaque titration that can be implemented at a standard conventional temperature without the need for additional special equipment.

The mechanism of proppant transport dynamic propagation in rough fracture for supercritical CO2 fracturing

Supercritical CO2 fracturing technology has shown great potential for enhancing production in unconventional reservoirs. It is essential to clarify the transport mechanism of proppant under the dynamic propagation conditions within rough fractures. A realistic rough fracture model is reconstructed, and Computational Fluid Dynamics simulations are conducted to track proppant movement during fracture propagation. The typical transport characteristics of proppant within rough fractures are revealed, and the effects of fracture propagation rate, proppant density, mass flow rate, particle size, sand ratio, and temperature on the support effect are discussed. The results show that the flow channels formed by sand carrying fluid in rough fractures are complex, with fracture propagation changing some flow channels. The proppant forms an irregular sand bed interspersed with unfilled areas, and complex flow characteristics are generated. The increase in fractal dimension increases the resistance in the fluid flow process and affects the movement of the proppant, which tends to create unfilled areas. Low density and size of proppant can improve the proppant placement length. In a certain temperature range, high temperature injection of sand carrying fluid can improve the proppant placement effect. In addition, the low sand ratio and high mass flow rate pumping can be used to form the dominant channel, followed by pumping with a high sand ratio and low mass flow rate for effective support.