STUDY OF INTERACTION OF SUPER HIGH FREQUENCY WAVES WITH GRAIN

The paper considers the interaction of ultrahigh-frequency waves with moist grains, in which the moisture information is represented as a function of two variables: the attenuation and phase shift of the electromagnetic wave. Wet material is represented as consisting of three flat layers: water, dry matter and air. Based on uncomplicated calculations, the conversion functions are derived and the influence of moisture, temperature and density coupling forms on the error of moisture conversion is studied.

Разработка инновационной энергосберегающей технологии очистки резервуаров путем диспергирования отложений

An obvious global trend in recent years is the increase in the proportion of viscous and heavy oils featured by high density and content of asphalt-resin-paraffin deposits. Due to the deterioration of the rheological properties of oil, the processes of its extraction, preparation in the fields, further transportation and subsequent processing have been made more difficult. The object of the study is the cleaning of oil and petroleum products storage tanks from the accumulated bottom sediments. The existing methods of tanks cleaning have been analyzed, the most promising methods and technical means for removing sediment and reducing the volume of sediment formation have been identified. The urgency of the development and implementation of innovative technologies enabling minimization of accumulation of deposit to reduce the scope of work in tank cleaning has been established. In this regard, experimental laboratory studies were conducted to determine the effectiveness of ultrasonic exposure with the occurrence of cavitation on the rheological properties of oil. The obtained results are indicative of a positive effect of ultrasound treatment of high-paraffin oil, such effect been expressed in decreased oil viscosity. A method is proposed for cleaning the tank from bottom sediments with the use of hydraulic washout system and ultrasonic plant. That method is based on the use of the cavitation effect caused by high-frequency waves, which makes it possible to temporarily adjust the rheological properties of oil and sludge deposit, reduce the deposit deposition rate and thereby slow down the process of sediment deposition during the storage of oil and petroleum products in large-volume tanks. Очевидной тенденцией последних лет в мире является увеличение доли вязких и тяжелых нефтей, характеризующихся высокой плотностью и содержанием асфальтосмолопарафиновых отложений. Вследствие ухудшения реологических свойств нефти затрудняются процессы ее добычи, подготовки на промыслах, дальнейшей транспортировки и последующей переработки. Объектом исследования является очистка резервуаров для хранения нефти и нефтепродуктов от образующихся донных отложений. Проанализированы существующие способы очистки резервуаров, выявлены наиболее перспективные методы и технические средства для удаления осадка и снижения объема образования отложений. Установлена актуальность вопроса разработки и использования инновационных технологий, позволяющих минимизировать выпадение осадка с целью уменьшения объема работ при очистке резервуаров. В этой связи проведены экспериментальные лабораторные исследования для определения эффективности ультразвукового воздействия с возникновением кавитации на реологические свойства нефти. Полученные результаты свидетельствуют о положительном эффекте обработки ультразвуком высокопарафинистой нефти, который выражается в снижении ее вязкости. Предложен способ очистки резервуара от донных отложений с применением гидравлической системы размыва и ультразвуковой установки. Он основан на использовании эффекта кавитации, вызываемой посредством высокочастотных волн, что позволяет провести временную корректировку реологических свойств нефти и осадка нефтешлама, снизить скорость выпадения осадка и таким образом замедлить процесс образования отложений при хранении нефти и нефтепродуктов в резервуарах большого объема.

Were recently reported MHz events planet mass primordial black hole mergers?

A bulk acoustic wave cavity as high frequency gravitational wave antenna has recently detected two rare events at 5.5MHz. Assuming that the detected events are due to gravitational waves, their characteristic strain amplitude lies at about $$h_c\approx 2.5 \times 10^{-16}$$ h c ≈ 2.5 × 10 - 16 . While a cosmological signal is out of the picture due to the large energy carried by the high frequency waves, the signal could be due to the merging of two planet mass primordial black holes ($$\approx 4\times 10^{-4} M_\odot $$ ≈ 4 × 10 - 4 M ⊙ ) inside the Oort cloud at roughly 0.025 pc (5300 AU) away. In this short note, we show that the probability of one such event to occur within this volume per year is around $$1:10^{24}$$ 1 : 10 24 , if such Saturn-like mass primordial black holes are $$1\%$$ 1 % of the dark matter. Thus, the detected signal is very unlikely to be due the merger of planet mass primordial black holes. Nevertheless, the stochastic background of saturn mass primordial black holes binaries might be seen by next generation gravitational wave detectors, such as DECIGO and BBO.

Automatic Detection and Classification of Boundary Crossings in Spacecraft in situ Data

<p>Planetary magnetospheres create multiple sharp boundaries, such as the bow shock, where the solar wind plasma is decelerated and compressed, or the magnetopause, a transition between solar wind field and planetary field.<br />We attempt to use convolutional neural networks (CNNs) to identify magnetospheric boundaries, i.e.  planetary and interplanetary shocks crossings and magnetopause crossings in spacecraft in situ data. The boundaries are identified by a discontinuity in a magnetic field, plasma density, and in the spectrum of high-frequency waves. These measurements are available on many planetary missions. Data from Earth's missions Cluster and THEMIS are used for CNN training. We ultimately strive for successful classification of boundaries (shock, magnetopause, inbound, outbound) and the correct handling of multiple crossings.</p>

Abundant breather and semi-analytical investigation: On high-frequency waves’ dynamics in the relaxation medium

This paper investigates the high-frequency waves’ dynamical behavior in the relaxation medium through two recent analytical schemes. This study depends on the Vakhnenko–Parkes (VP) equation that has been reduced from the well-known Ostrovsky equation. The modified Khater (MKhat) and the extended simplest equation (ESE) methods are used to handle the considered model. As a result, many novel solitary wave solutions have been obtained to construct the initial and boundary conditions. These conditions allow employing the variational iteration (VI) method to study the semi-analytical solutions of the considered model. The accuracy of solutions is explained along with showing the matching between analytical and semi-analytical solutions and comparing our obtained solutions with the previous results that have been obtained in published research papers. Moreover, the high-frequency waves’ behavior relaxation medium is illustrated through some distinct sketches. The methods’ performance shows their effectiveness, direct, easy, and consequential for studying many nonlinear evolution equations.

Convectively-coupled High-frequency waves triggered Kerala floods in 2018 and 2019

Floods have repeatedly battered the South Indian state, Kerala, as a result of extremely anomalous rainfall during Boreal Summers, since 2018. Previous studies have seldom adopted a systematic approach to understand the phenomenon responsible for the extreme events. Hence, this study intends to identify this dynamical phenomenon based on spectral methods, and attempts to render a preliminary solution to the problem. The study exposes the presence of westward-propagating high-frequency tropical atmospheric waves of 5-8 days period, which originated from east Indian Ocean or West Pacific and headed towards the east coast of Africa. The wave troughs ensured sufficient moisture availability along its path, causing extreme precipitation over Kerala on the way.

The need for new techniques to identify the high-frequency MHD waves of an oscillating coronal loop

Context. Magnetic arcades in the solar atmosphere, or coronal loops, are common structures known to host magnetohydrodynamic (MHD) waves and oscillations. Of particular interest are the observed properties of transverse loop oscillations, such as their frequency and mode of oscillation, which have received significant attention in recent years because of their seismological capability. Previous studies have relied on standard data analysis techniques, such as a fast Fourier transform (FFT) and wavelet transform (WT), to correctly extract periodicities and identify the MHD modes. However, the ways in which these methods can lead to artefacts requires careful investigation. Aims. We aim to assess whether these two common spectral analysis techniques in coronal seismology can successfully identify high-frequency waves from an oscillating coronal loop. Methods. We examine extreme ultraviolet images of a coronal loop observed by the Atmospheric Imaging Assembly in the 171 Å waveband on board the Solar Dynamics Observatory. We perform a spectral analysis of the loop waveform and compare our observation with a basic simulation. Results. The spectral FFT and WT power of the observed loop waveform is found to reveal a significant signal with frequency ∼2.67 mHz superposed onto the dominant mode of oscillation of the loop (∼1.33 mHz), that is, the second harmonic of the loop. The simulated data show that the second harmonic is completely artificial even though both of these methods identify this mode as a real signal. This artificial harmonic, and several higher modes, are shown to arise owing to the periodic but non-uniform brightness of the loop. We further illustrate that the reconstruction of the ∼2.67 mHz component, particularly in the presence of noise, yields a false perception of oscillatory behaviour that does not otherwise exist. We suggest that additional techniques, such as a forward model of a 3D coronal arcade, are necessary to verify such high-frequency waves. Conclusions. Our findings have significant implications for coronal seismology, as we highlight the dangers of attempting to identify high-frequency MHD wave modes using these standard data analysis techniques.

Studies of Spectral Broadening of the Lower Hybrid Wave Line in the Current-Drive Regimes and Ion Heating at the FT-2 Tokamak

The experiments at the FT-2 tokamak are described that were focused on clearing up the role of the parametric decay instabilities in decreasing the generation efficiency of the non-inductive current excited by the electromagnetic waves in the lower hybrid frequency range. The most discussed instability of such kind is the decay of the pump wave into the daughter high-frequency waves and the low-frequency ion–acoustic quasi-modes. The studies performed have shown that, under conditions of the FT-2 experiment, the ion–acoustic instability has no decisive effect on the decrease in the efficiency of the lower hybrid current drive.

From weekly to seasonal variability of the North Brazil - Equatorial Undercurrent retroflection

<p>The northward flow in the western tropical Atlantic Ocean is carried mainly by North Brazil Current (NBC), hence playing a major role in the cross-equatorial exchange of properties. As thermocline waters reach the equator, they largely retroflect to feed the Equatorial Undercurrent (EUC), a quasi-permanent zonal current that brings salty and highly-oxygenated waters to the eastern side of the basin. This retroflection system is governed by the zonal pressure gradient, which is driven by the trade winds. Hence, the wind fluctuations represent the major source of variability at seasonal and interannual scales. However, at shorter time scales, the variability of the retroflection system may be associated with both interior and coastal waves. In the present study we describe the water mass balance at the NBC-EUC retroflection area using a combination of shipboard observations and numerical reanalysis. The observations, from an oceanographic campaign in April 2010, provide a synoptic view of the retroflection region and allow assessing the goodness of the numerical data. We then use the ocean reanalysis GLORYS2v4 to analyse the temporal variability of this region, from intra-seasonal to seasonal scales, and use Lagrangian simulations to identify the principal water mass pathways feeding the retroflection. We find a substantial seasonal cycle in the boundary and interior (southern and northern) origins of those waters that feed the EUC. Our results also show the propagation of high-frequency waves (16-30 days) along the coast from the south, probably as coastal trapped waves, while waves with 30-60 days period come from the northern hemisphere, probably as westward Rossby waves reach the coast of America and follow south as Kelvin waves. These short-term fluctuations have a high impact on the water mass pathways that feed the EUC and the retroflection structure itself.</p>