Equilibrium and oscillations of liquid fuel free surface in coaxial-cylindrical vessels under microgravity conditions

In the absence of significant mass forces, the behavior of liquid fuel under microgravity conditions is determined by surface tension forces, which are intermolecular forces at the interface of two phases. The paper posed and solved the problem of equilibrium and small oscillations of an ideal liquid under microgravity conditions, and also quantified the influence of various parameters: the contact angle α0, the Bond number, the ratio of the radii of the inner and outer walls of the vessel and the depth of the liquid. For the coaxial-cylindrical vessels, there were obtained expressions in the form of a Bessel series for the potential of the fluid velocities and the free surface displacement field. The study relies on the analytical and experimental data available in the literature and proves the reliability of the developed numerical algorithm. Findings of research show that for and r, with the physical state of the wetted surface being unchanged, the shape of the free surface tends to be flat and the contact angle has little effect on the intrinsic vibration frequency of the free surface of the liquid. The results obtained can be used to solve problems of determining the hydrodynamic characteristics of the movement of liquid fuel in outer space.

Multifrequency radar observations of clouds and precipitation including the G-band

Observations collected during the 25 February 2020 deployment of the Vapor In-Cloud Profiling Radar at the Stony Brook Radar Observatory clearly demonstrate the potential of G-band radars for cloud and precipitation research, something that until now was only discussed in theory. The field experiment, which coordinated an X-, Ka-, W- and G-band radar, revealed that the Ka–G pairing can generate differential reflectivity signal several decibels larger than the traditional Ka–W pairing underpinning an increased sensitivity to smaller amounts of liquid and ice water mass and sizes. The observations also showed that G-band signals experience non-Rayleigh scattering in regions where Ka- and W-band signal do not, thus demonstrating the potential of G-band radars for sizing sub-millimeter ice crystals and droplets. Observed peculiar radar reflectivity patterns also suggest that G-band radars could be used to gain insight into the melting behavior of small ice crystals. G-band signal interpretation is challenging, because attenuation and non-Rayleigh effects are typically intertwined. An ideal liquid-free period allowed us to use triple-frequency Ka–W–G observations to test existing ice scattering libraries, and the results raise questions on their comprehensiveness. Overall, this work reinforces the importance of deploying radars (1) with sensitivity sufficient enough to detect small Rayleigh scatters at cloud top in order to derive estimates of path-integrated hydrometeor attenuation, a key constraint for microphysical retrievals; (2) with sensitivity sufficient enough to overcome liquid attenuation, to reveal the larger differential signals generated from using the G-band as part of a multifrequency deployment; and (3) capable of monitoring atmospheric gases to reduce related uncertainty.

Marangoni convection in the transient flow of hybrid nanoliquid thin film over a radially stretching disk

Within a magnetohydrodynamic environment, Marangoni convection (Thermocapilarity effect) in an unsteady thin film of hybrid nanoliquid flow over a disk has been discussed. A set of simplified Navier-Stokes equation using boundary layer theory is written in order to model the above mentioned flow situation. The dissipative effects caused by viscosity and magnetic field have been incorporated in temperature-balance equation. A suitable choice of transform variables facilitate a system of ordinary differential equations (ODEs) from original partial differential equations (PDEs) representing the flow phenomena. This system of ODEs are solved by shooting technique in conjunction with Runge-Kutta 4th order numerical scheme. This study reveals that by increasing the surface tension along the liquid-air interface, the velocity of hybrid nanoliquid can be increased. In the context of this research work, the hybrid nanoliquid prepared by dispersing blade shaped [Formula: see text] and Cu nanoparticles, is an ideal liquid as far as liquid coolants are concerned.

METHOD OF DISCRETE FEATURES AS PLANNING MEANS IS AERODYNAMIC OUTLINES OF TRANSPORT VEHICLES

The main stages of the development of the discrete singularities’ method are described. Modern results on the numerical solution of boundary hypersingular integral equations by the methods of collocations and piecewise constant approximations are given. The modern going near planning of aerodynamic design outline of transport vehicles conditionally can be divided into three stages: engineering approaches are close, design on the basis of methods of discrete singularities, approaches that arе based on integration of complete and the Reynolds-averaged of Navier-Stokes equations. On the first stage various engineering approaches are used for forming of aerodynamic outline, going out a requirement specification and requirements of customer. Close geometrical and aerodynamic descriptions are determined in the first. An aerodynamic outline is formed in the first close. On the second stage it follows to use more difficult models of aerodynamics on the basis of various approaches that is built on the model of ideal liquid. Bearing properties are determined, power and moment characteristics for the corresponding outline of aircraft. The third stage is most difficult and expensive cost. On this stage it follows to use methods and models that are based on equations for turbulent flow. The second stage is in-process considered – as means of the previous planning of aerodynamic arrangement with the use of methods of discrete features. A non-stationary chart in that tearing away is designed from all sharp edge of wing is in-process used. This chart has the most general case of forming of process of flowing around of the bearing system of aircraft. However, complication of physical interpretation of forming of such processes in the conditions of ideal liquid remains problematic. The necessities of practice require expansion and deepening of theoretical approaches for the study of non-stationary. Application of model of ideal liquid for the calculation of the bearing system of a perspective transport vehicle allows to set forth aerodynamic task as task of Neumann for Laplace operator. The calculations of the bearing systems of difficult geometrical plane form are conducted. Dependences of carrying capacity and longitudinal moment are got depending on the corner of attack and distance to the ground clearance. A computational experiment confirmed that a method of discrete vorteces was one of important methods of computational aerodynamics. He is effective means for untiing of a number of aerodynamic tasks.

VIBRATIONS OF A LONGITUDINALLY STIFFENED, LIQUID-FILLED CYLINDRICAL SHELL IN LIQUID

In the paper we study free vibrations of a longitudinally stiffened, viscous liquid-filled orthotropic cylindrical shell in ideal liquid. The Navier – Stokеs linearized equation is used to describe the motion of the internal viscous liquid, the motion of the external liquid is described by a wave equation written in the potential by perturbed velocity. Frequency equation of a longitudinally stiffened orthotropic, viscous liquid-contacting cylindrical shell is obtained on the basis of the Hamilton – Ostrogradsky principle of stationarity of action. Characteristic curves of dependence are constructed.

First Light Multi-Frequency Observations with a G-band radar

Observations collected during the 25-February-2020 deployment of the Vapor In-Cloud Profiling Radar at the Stony Brook Radar Observatory clearly demonstrate the potential of G-band radars for cloud and precipitation research, something that until now was only discussed in theory. The field experiment, which coordinated an X-, Ka, W- and G-band radar, revealed that the Ka-G pairing can generate differential reflectivity signal several decibels larger than the traditional Ka-W pairing underpinning an increased sensitivity to smaller amounts of liquid and ice water mass and sizes. The observations also showed that G-band signals experience non-Rayleigh scattering in regions where Ka- and W-band signal don’t, thus demonstrating the potential of G-band radars for sizing sub-millimeter ice crystals and droplets. Observed peculiar radar reflectivity patterns also suggest that G-band radars could be used to gain insight into the melting behavior of small ice crystals. G-band signal interpretation is challenging because attenuation and non-Rayleigh effects are typically intertwined. An ideal liquid-free period allowed us to use triple frequency Ka-W-G observations to test existing ice scattering libraries and the results raise questions on their comprehensiveness. Overall, this work reinforces the importance of deploying radars with 1) sensitivity sufficient to detect small Rayleigh scatters at cloud top in order to derive estimates of path integrated hydrometeor attenuation, a key constraint for microphysical retrievals, 2) sensitivity sufficient to overcome liquid attenuation, to reveal the larger differential signals generated from using G-band as part of a multifrequency deployment, and 3) capable of monitoring atmospheric gases to reduce related uncertainty.

Development and Evaluation of Thermodynamic Models for Predicting Cold Flow Properties of Biodiesel

Biodiesel, especially palm oil-based methyl esters (PME), is steadily increasing in consumption in Indonesia and Malaysia as a petroleum diesel substitute. PME has poor cold flow properties due to the presence of saturated bound glycerols. Bound glycerols, such as monoglycerides (MAGs), diglycerides (DAGs), and triglycerides (TAGs), are impurities in biodiesel as a result of incomplete transesterification, and have high melting points. These minor components often solidify even at temperatures higher than the cloud point and thus cause clogging in fuel filters. It is, therefore, essential to predict the solidification temperature for the application of biodiesel, particularly in high blending levels. This study developed and evaluated thermodynamic models for predicting the solidification of biodiesel. Binary and multicomponent mixtures of fatty acid methyl esters (FAMEs) and bound glycerols were prepared as biodiesel models. The solidification temperature was measured by differential scanning calorimetry and the results were compared with the predicted values. It was discovered that most of the binary mixtures of a FAME and a bound glycerol (MAG, DAG, or TAG) behaved as eutectic systems, in which a solid phase consists of a single component. In the case of the eutectic system, the solidification temperature could be estimated by assuming non-ideal liquid solutions, and the modified UNIFAC (Dortmund) model helped calculate the activity coefficient. However, the mixtures of MAG/MAG differed from the eutectic system, suggesting that the solid compounds of different types of MAGs were formed. Thus, the compound formation model was developed, which was successful in predicting the solidification temperatures of biodiesel model fuels that consist of several kinds of FAMEs and MAGs.

EVQuant; high-throughput quantification and characterization of extracellular vesicle (sub)populations

Extracellular vesicles (EVs) reflect the cell of origin in terms of nucleic acids and protein content. They are found in biofluids and represent an ideal liquid biopsy biomarker source for many diseases. Unfortunately, clinical implementation is limited by available technologies for EV analysis. We have developed a simple, robust and sensitive microscopy-based high-throughput assay (EVQuant) to overcome these limitations and allow widespread use in the EV community. The EVQuant assay can detect individual immobilized EVs as small as 35 nm and determine their concentration in biofluids without extensive EV isolation or purification procedures. It can also identify specific EV subpopulations based on combinations of biomarkers and is used here to identify prostate-derived urinary EVs as CD9-/CD63+. Moreover, characterization of individual EVs allows analysis of their size distribution. The ability to identify, quantify and characterize EV (sub-)populations in high-throughput substantially extents the applicability of the EVQuant assay over most current EV quantification assays.