 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | | The end of the list has been reached or no journals were found for your choice. |
|
|
- Inertial Wave Beam Path in a Non-uniformly Rotating Cylinder with Sloping
Ends-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The features of the inertial wave beam propagation in a librating cylindrical cavity with symmetrically inclined end-walls are experimentally studied. The geometry provides the existence of two flow regimes – inertial wave attractor and the case of symmetric beam reflection that is like the closed periodic orbit in a rotating spherical shell. Despite the visual similarity, the nature of the regimes is different. The first is due to the geometric focusing of the beams into the limit cycle after a series of reflections from sloping ends, and the second with the symmetry wave path for a given frequency and cavity geometry. Although the geometry of the problem is three-dimensional, these regimes are almost two-dimensional: the closed wave trajectory is trapping near the plane of the direction of the slope gradient of the ends. Also, we study the scaling laws for the width and amplitude of the oscillating shear layers in the axial section. At large amplitudes of the librational forcing, the global azimuthal vorticity grows in a quadratic manner, which indicates the development of a nonlinear regime of inertial waves. Fourier analysis shows that a spectrum, besides the fundamental frequency, contains two sets of closely spaced subharmonic frequencies that satisfy the triadic resonance condition.
PubDate: 2023-06-01
- Integrated Analysis of MRNA and MiRNA Expression Profiles in dys-1 Mutants
of C. Elegans After Spaceflight and Simulated Microgravity-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Dystrophin-like dys-1 gene is expressed and required in muscle tissue, playing a vital role in gravisensing in Caenorhabditis elegans (C. elegans). To date, microRNA (miRNA)-mediated epigenetic mechanism in microgravity-induced muscular atrophy remains to be elucidated. In the present study, we first analyzed mRNA and miRNA expression profiles in space-flown dys-1(cx18) mutants and wild type worms (wt) of C. elegans. The results showed that spaceflight and microgravity have fewer effects on mRNA and miRNA expression in dys-1 mutant than in wt worms. mRNA and miRNA expression patterns of dys-1 mutants were changed by microgravity. Hierarchical clustering analysis showed that the alterations of genes function on neuromuscular system under space environment. Seven miRNAs (cel-miR-52, 56, 81, 82, 84, 124 and 230) have 18 significant anti-correlated target genes under space environment. RT-qPCR analysis confirmed that miR-52 and cdh-3, miR-84 and lin-14, miR-124 and mgl-3 in dys-1 mutants reversely altered under microgravity environment and in simulated microgravity experiment. Locomotion ability was only reduced in F0 wt worms but not in dys-1 mutants as well as their F1 offspring after simulated microgravity. We observed expression alterations of 7 neuromuscular genes (unc-27, nlp-22, flp-1, egl-5, flp-4, mgl-3, unc-94) in F0 wt worms, which might be involved in the regulation of locomotion ability of C. elegans. This study provides important insights to reveal the mechanism in the pathogenesis of muscular atrophy induced by microgravity.
PubDate: 2023-06-01
- Stability and Bifurcation Analysis of Two-Immiscible Liquids Film Down an
Inclined Slippery Solid Substrate-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this work, the dynamic behavior of linear and nonlinear waves propagating at the separating surface between two thin layers of viscous Newtonian fluids is studied in the presence of the effect of insoluble surface surfactant. The two liquids are confined between two infinite rigid parallel plates and assumed to have different densities and viscosities. The equations of evolution for surface-wave elevation and concentration of surfactant are derived using the lubrication approximation. In the linear stage, by utilizing the normal mode approach, we have derived the dispersion relation that relates the wave angular frequency to the wave number and other parameters that is solved numerically to inspect the influences of some selected parameters on the stability criteria of the fluid flow. Also, analytical expressions for the growth rate as well as its maximum value with corresponding wave number are obtained in the special case of long-wave limiting. It is concluded that the Marangoni number \(\text {Ma}\) has acquired a significant stabilizing influence on the fluid flow, whereas the inverse of the slippery length of substrate plate \(\beta\) , resorts to the destabilize the motion of the interfacial waves. Consequently, both of the Marangoni number and the substrate slippy coefficient can be utilized to control the film flow regime, where they preserve the film laminar flow and tend to prevent the film breakdown. These can be useful in many industrial applications such as coating processes, heat exchangers, cooling microelectronic devices, chemical reactors, food processing, thermal protection design of combustion chambers in rocket engines and operation of Laser cutting and heavy casting production processes.
PubDate: 2023-05-27
- Peculiarities of Surfactant Extraction by a Droplet from its Homogeneous
Solution-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The process of surfactant extraction by a droplet from the surrounding homogeneous solution was studied experimentally via selecting the system of liquids in which the surfactant concentration in the droplet (upon completion of the diffusion) is many times higher than its initial concentration in the environment. It has been found that, under normal gravity, a significant concentration gradient is formed in the droplet, which results in the development of Marangoni convection, although an external gradient is absent. Visualization of flow patterns and concentration fields in the droplet and the environment made it possible to trace their evolution and to determine the conditions for occurrence of an oscillatory mass transfer regime. The results obtained demonstrate how the surfactant concentration and its vertical distribution vary vs. the droplet diameter, the initial surfactant concentration in the surrounding liquid and the time elapsed from the droplet formation.
PubDate: 2023-05-26
- Development of an Experimental Device for the Assessment of Emulsions
Dynamic Behavior and Stability in Micro-gravity-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Emulsions are encountered in foods, cosmetics and pharmaceuticals. Their stability depends strongly on gravity (creaming or sedimentation) and interface driven destabilization mechanisms (coalescence or aggregation) occurring after their production. Although of great significance, coalescence and aggregation cannot be studied in-depth on ground due to coupling with gravity driven mechanisms. To overcome this restriction, the design, development and preliminary testing of a new experimental device to be used in the forthcoming ESA parabolic flights for the evaluation of emulsion dynamic behavior and stability under low gravity conditions, is presented. Such conditions allow to get rid of creaming and sedimentation and, thus, to isolate droplets coalescence and aggregation. A novel miniature emulsification cell, along with advanced electrical and optical diagnostics to produce and investigate emulsions are incorporated to custom experimental cells. Optical diagnostics include a high speed camera (up to 750.000 fps) to monitor droplets breakup and droplet-droplet interactions and a high resolution DSLR camera (20MP) to determine droplet size distribution. The EU patented I-VED electrical impedance spectroscopy technique (EP 3 005 942 A1, 2016) is employed to monitor the evolution of oil volumetric fraction as a function of time and gravity. Experimental parameters under study include: oil volume fraction, surfactant concentration, pulsation duration and stroke frequency for emulsification. The implementation of the experimental device, including two racks and one baseplate, complies with ESA technical requirements and safety regulations, while a number of experiments on-ground with a conventional oil-in-water emulsion validates it from a technical and functional point of view.
PubDate: 2023-05-25
- Viscous Effect on the Frequency Shift of an Oscillating-Rotating Droplet
-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: For an inviscid, spherical, infinitesimal-amplitude oscillating droplet, the surface tension is obtained by the oscillation frequency based on the linear theory. In reality, however, it is not fully applicable due to the severe presuppositions and frequency shift appears which introduces non-ignorable measurement errors in surface tension. In this work, a series of three-dimensional simulations were conducted to investigate the influence of property ratio, oscillation amplitude, viscous effect as well as rotation rate on frequency shift of an oscillating droplet. With the increase of oscillation amplitude, negative frequency shift was observed while positive frequency shift appears with increasing rotation rate, during which the viscous dissipation played role of hindering it. An empirical formula was proposed to determine the frequency shift of an oscillating-rotating droplet and it is in good agreement with experimental results. With this work, it was expected that the measurement accuracy of surface tension of droplet can be further enhanced by considering the frequency shift induced by amplitude, rotation and viscous effect.
PubDate: 2023-05-19
- Numerical Modelling for the Droplets Formation in Microfluidics - A Review
-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Microfluidic technology has advantages in producing high-quality droplets with monodispersity which is promising in chemical engineering, biological medicine and so on. An in-depth study on the underlying mechanism of droplet formation in microfluidics is of great significance, and to understand it, numerical simulation is highly beneficial. This article reviews the substantial numerical methods used to study the fluid dynamics in microfluidic droplet formation, mainly including the continuum methods and mesoscale methods. Moreover, the principles of various methods and their applications in droplets formation in microfluidics have been thoroughly discussed, establishing the guidelines to further promote the numerical research in microfluidic droplet formation. The potential directions of numerical modelling for droplet formation in microfluidics are also given.
PubDate: 2023-05-16
- Method of Taking into Account Influence of Thermal Shock on Dynamics of
Small Satellite and its Use in Analysis of Microaccelerations-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The article resents a method that allows taking into account the effect of thermal shock on the satellite dynamics. This method make possible to correct the motion model of a small satellite by adding effect of thermal shock to the model. Numerical modeling was carried out to analyze microaccelerations from thermal shock in the a one-dimensional model of thermal conductivity. The results of the research can be used to create small satellite for technological purposes.
PubDate: 2023-05-09
- Three-Dimensional Phase Interface Reconstruction of Micro-Grooved Heat
Pipe Based on Optical Sectioning Microscopy-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this paper, the three-dimensional vapor–liquid two-phase interface reconstruction of the micro-grooved heat pipe is investigated by a visualization system based on the principle of optical sectioning microscopy. Three-dimensional distribution characteristics of the vapor–liquid interface and heat transfer regimes are analyzed. In addition, the effects of heat load on transport characteristics of the liquid phase between evaporator and condenser are examined. The results indicate that gravity has weak effects on distribution of the liquid layer in direction of axial and radial, the liquid layer distributes in sharp corners of the square groove or covers the wall of the groove almost symmetrically. Differing from gravity, the effect of surface tension on distribution of the liquid phase is significant, the vapor–liquid two-phase interface of the condensate liquid plug distributes in central region of grooves symmetrically as a shape of the bullet, and the warhead points to condenser. Driven by the capillary pressure difference, the condensate flows from condenser through the adiabatic to evaporator. And the thickness of the liquid layer covering the inner wall of the groove decreases gradually from condenser to evaporator. The increase of heat load strengthens the circulation of the working medium, increases the thickness of the liquid layer in condenser, and even leads to no liquid plug in condenser. Meanwhile, the increase of heat load can also promote evaporation in evaporator and reduce the thickness of the liquid layer in evaporator.
PubDate: 2023-05-04
- Experimental Investigation of Liquid Interface Stability During the
Filling of a Tank in Microgravity-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The storage of propellants in space as well as the transfer and filling of spacecraft tanks is a prerequisite for future long-term space exploration missions. In this work, the vented filling of a partially filled tank, which is envisioned as a spacecraft tank, was investigated experimentally under compensated gravity in the Bremen Drop Tower. Experiments were performed with a partially filled tank and a test liquid HFE-7500. The drop tower provides 9 s of compensated gravity. The shape of the free liquid surface inside a right circular cylinder changes from the normal gravity configuration to a free fall configuration during the test. The filling was initiated after 3.5 s and continued until the end at 9 s. The interaction of the incoming liquid jet with the liquid interface was studied for different volumetric flow rates. A stable, but not steady liquid interface was characterized by a deformation due to the incoming liquid jet and the formation of a geyser. The growth of the geyser and the following disintegration into liquid droplets indicated an unstable liquid interface. Subcritical, critical and supercritical regimes of the volumetric flow rates were identified to classify stable and unstable liquid interfaces. The critical Weber number was found to be 1.04, which corresponds to a critical volumetric flow rate of 1.30 mL s-1. This critical Weber number was compared with the existing literature. Additionally, the behaviour of the liquid interface during the reorientation of the liquid inside the tank was observed.
PubDate: 2023-04-29
- Thermocapillary Bubble Oscillations and Migration in a Vibrating Cylinder
in a Zero-Gravity Environment-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Bubble migration in a vibrating zero gravity environment is numerically investigated using ANSYS-FLUENT software. A 3D CFD model is developed describing the two-phase flow of a nitrogen bubble immersed in a container full of ethanol. The Volume of Fluid (VOF) method and the geometric reconstruction scheme are used to track the gas–liquid interface. The liquid in the container is vibrated horizontally in the x momentum with different frequencies from 0 to 1 Hz, and amplitudes from 0.005 to 0.1 m/s2. The vibration impact on the bubble arrival time to the top and its ensuing dynamic is analyzed. Different bubble trajectory shapes are observed, other than the conventional vertical translation induced by the temperature difference. Compared to the no vibration case, the bubble motion is slightly either accelerated or decelerated for very low vibration amplitudes. For a fixed frequency f = 1 Hz, the bubble takes more time to reach the top with the vibration amplitude increment relatively to the no vibration case. The vibration effect becomes more intense with the Marangoni number decrease when f = 0.2 Hz and Ab = 0.005 m/s2. Those results are difficult to obtain experimentally, signifying the importance of this numerical study to understand bubble motion and migration in space.
PubDate: 2023-04-21
- Numerical Analysis of Microbubble Rising in an Oil–water Liquid Layer
under Gravity Based on Three-phase Field Method-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this paper, we conduct two-dimensional simulations based on three-phase field method to analyze the bubble rising behaviors in an oil–water liquid layer. During the rising process, if the inertial force is higher than the combined effect of interfacial tension and viscous force, the bubble will deform and successfully pass through the oil–water interface, otherwise, it will be trapped by the fluidic interface. And the microbubble will carry some water fluid into the oil phase when it passes through the oil–water interface. The effects of various factors including bubble diameter, liquid density, interfacial tensions, fluid viscosity and non-Newtonian properties of fluids on single bubble rising, deformation and entrainment are systematically studied. What’s more, the rising behaviors of two closely distributed bubbles are further analyzed. These conclusions can help to understand the mechanism of bubble rising in an oil–water liquid layer under gravity and give useful guidelines for those applications concerning bubble rising such as the flow boiling for heat sink in space science.
PubDate: 2023-04-13
- Connection of Dried Blood Spot Proteomic Composition Dynamics and Heart
Rate Variability in 3-day Female Dry Immersion-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: For the first time, the peculiarities of the blood proteomic composition depending on the predominance of the vegetative regulation type were analyzed under the conditions of dry immersion in women volunteers (age 30.17 ± 5.5 years, height 1.66 ± 0.1 m, weight 62.05 ± 8.4 kg, BMI 22.39 ± 2.2 kg/m2) with a natural menstrual cycle. The experiment “NAIAD-2020” was carried out at the Institute of Biomedical Problems (Moscow, Russia). It has been shown that under normal motor activity (in baseline studies), in individuals with various modulating types of autonomic influences, energy expenditure is provided mainly by carbohydrate metabolism, which has genetic features in the implementation of the pentose pathway. During dry immersion, with minimal motor activity, energy expenditure sharply decreases, leveling out vagus-mediated differences between the groups. On the second day of the recovery period, processes related to the functions of heat shock proteins and excosomes were noted.
PubDate: 2023-03-31
- Numerical Simulation of Vapor Configuration and Bubbles Coalescence in
Cryogenic Propellant Tank Under Microgravity-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The Volume of Fluid (VOF) method was used to numerically study the configuration characteristics of the vapor region in the cryogenic propellant tank under microgravity in this study. The deformation characteristics of the gas–liquid interface, the bubble motion and coalescence characteristics in the tank were analyzed. The liquid infiltration and liquid infiltration expansion were proposed to evaluate the vapor region deformation characteristics under microgravity, and the stagnation time was proposed to describe the bubble motion characteristics. Results showed that the surface tension drove the liquid to climb along the wall under microgravity. When the filling rate was 95%, the liquid infiltration decreased as the contact angle and the gravity level increased. Under 10−5 g gravity level, when the contact angle was 5°, the tank with 80% filling rate had the largest increased infiltration area, while the infiltration expansion ratio decreased when the filling rate was less than 65%. The average velocity of the bubble motion increased with the increase of Eötvös number (Eo). When the radius of the bubble located in the center of the tank was less than 100 mm, the bubble had a stagnation period before moving. The stagnation time increased with the decrease of the bubble radius. Multiple bubbles could coalesce to form a large bubble similar to an ellipsoid under microgravity. The results verified the feasibility of the lumped vapor method under microgravity, and the finally stable shape of the vapor region was similar to an ellipsoid.
PubDate: 2023-03-31
- Onset of Penetrative Convection in a Multilayered Heat-generating Porous
System with Thin Air Interlayers-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The study is devoted to a new problem concerning the onset of penetrative convection via internal heating in a multilayered air-porous system under the gravitational field. The system consists of porous sublayers separated by thin air interlayers. The governing equations are supplemented by the effective boundary conditions which contain the interlayer parameter and parameter of thermal conductivity jump. The parameters are combinations of the relative air interlayer depth, Darcy number and thermal conductivity ratio. The numerical results show that the large-scale convection covering the entire unstably stratified upper region initiates in a multilayered system with porous sublayers of equal depth and permeability. The addition of air interlayers speeds up the convection onset and increases the wavelength of convective patterns. The effect becomes stronger as the number of porous sublayers increases because the number of air interlayers also increases. Local convection can be obtained when the permeability of any one porous sublayer exceeds that of the other porous sublayers by an order of magnitude or more. The local flow originates in the highly permeable porous sublayer that belongs to the upper half of the system. Convection becomes of a large scale at any other position of this sublayer. It is found that the permeability ratio can be both destabilizing and stabilizing. It is explained by a transition from the large-scale to local convective regimes. The destabilizing effect of air interlayers is observed for both local and large-scale regimes in the multilayered system with a highly permeable porous sublayer.
PubDate: 2023-03-18
DOI: 10.1007/s12217-023-10043-2
- Effects of Thermocapillary and Natural Convection During the Melting of
PCMs with a Liquid Bridge Geometry-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The results of a numerical investigation of the melting of a PCM occupying an axisymmetric volume in the presence of gravity are presented. The PCM is held between two circular supports maintained at different temperatures. The melting process, which is analyzed for n-octadecane, is affected by a combination of thermocapillary and natural convection. If the PCM is heated from above, the convective motion driven by the thermocapillary force is opposed by the buoyant force, which reduces the heat transfer rate. If the PCM is heated from below, natural convection acts in the same sense as thermocapillary convection and the heat transfer rate is increased. The volume \(\mathcal {V}\) of the PCM relative to an ideal cylinder, which selects the shape of the PCM/air interface, is found to play an important role. The overall effect of natural convection on heat transfer is characterized by the ratio of the melting time in microgravity to that of the same system with gravity. This gain factor is greater (less) than unity when heating from below (above) and depends strongly on \(\mathcal {V}\) , particularly for smaller PCM volumes.
PubDate: 2023-03-13
DOI: 10.1007/s12217-023-10040-5
- Volume of Fluid Simulations of Heat Transfer in Liquid-Liquid Segmented
Flows in Microfluidic channel-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: This study presents the investigations on the effect of heat transfer on droplet formation in T-type microfluidic channel. Mineral oil acts as a continuous phase, and water acts as a dispersed phase. The Volume of Fluid model is used to investigate the formation of droplets of water in oil in the microchannel. The physical properties of both fluids change with an increase in temperature of dispersed phase, of which the dominant properties are viscosities of fluids and interfacial tension. The parameters such as droplet diameter, distance between two consecutive droplets and detachment time were studied with respect to temperature in the range of 300 K to 325 K. These properties are also studied at different flow rate ratios 0.125, 0.25, and 0.5. The distance between two consecutive droplets was found to decrease with the increase in temperature due to the rapid motion of droplets in the temperature zone. The droplet detachment time also decreases, due to the decrease in interfacial forces which hold the droplets in the dispersed phase. The droplet diameter decreases initially with the increase in temperature, but it was observed that after 320 K the diameter of the droplet increases due to the coalescence of two consecutive droplets downstream in the microchannel. This temperature is reported as a limiting condition for thermally controlled water-in-oil microemulsions.
PubDate: 2023-03-10
DOI: 10.1007/s12217-023-10041-4
- Development and Validation of a Novel Head-down Tilt Microgravity
Simulation Device for Canines-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The simulation of a microgravity environment on earth is an effective strategy to perform studies on the physiological effects of microgravity. Studying the microgravity-related physiological changes in canines is more effective rather than studying those in smaller animals such as rats. However, presently, no microgravity simulation models have been established with respect to canines. A novel canine head-down tilt microgravity (CHDTM) simulation device was developed based on the characteristic physiological structure and habits of canines. Beagles were subjected to head-down tilt (HDT) rest at tilt angles of −6° and −12°, respectively, for 21 d, or subjected to HDT bed rest (−12°) for 7, 14, and 21 d, respectively. The changes in the bone and muscle metabolisms of beagles subjected to this HDT model was investigated, including the hind limb muscle content, the expression of myosin, troponin, MuRF-1, and atrogin-1 in their soleus muscles, and the serum concentrations of alkaline phosphatase (ALP), osteocalcin, and calcium. The CT imaging of femurs was performed to estimate the cortical thickness (Ct.Th), bone area (BArea), bone volume/tissue volume (BV/TV), and trabecular number (Tb.N). The simulated state of weightlessness of the beagles in the −12° groups for 21 d significantly affected the bone (serum ALP, osteocalcin and calcium content, bone density) and muscle metabolism (hind limb circumference, the expression of myosin, troponin, MuRF-1, and atrogin-1 in soleus muscles) of the canines, which is consistent with the results of previous studies associated with the physiological effects of microgravity. The parameters in the beagles in the −12° HDT groups for 7 and 14 d were not significantly different from Control group. The weightlessness simulation was successful when beagles were subjected to −12° HDT for 21 d. The novel CHDTM simulation device developed in the study could be used in the weightlessness simulation experiment and pharmaceutical development of large animals.
PubDate: 2023-03-01
DOI: 10.1007/s12217-023-10039-y
- Direct Simulation on the Dynamics of Liquid Films Flowing Down a Fiber
-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Direct simulations on the dynamics of a liquid film coating on the outer surface of a vertical fiber are performed in the present paper. A domain mapping technique has been used on solving the Navier-Stokes problem in stream function form and predicts the dynamics of the various flow regimes with remarkable accuracy. We investigated the morphologies that develop in the coating flow down fiber and analyze the effects of Bond number and fiber diameter on the maximum liquid film height and drop speed. The results showed that the Bond number and fiber diameter have a significant effect on the instability. The transition between the Plateau-Rayleigh and convective regimes occurs at the conditions when the flow transitions from absolutely to convectively unstable.
PubDate: 2023-03-01
DOI: 10.1007/s12217-023-10032-5
- Dust Cloud Convections in Inhomogeneously Heated Plasmas in Microgravity
-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Convection is a phenomenon that often occurs in the presence of temperature gradients. In microgravity, free convection can not occur due to the lack of buoyancy. However, during parabolic flights we observed convections of microparticles in a gas discharge within the cylindrical plasma chamber of the setup PK-4. The microparticles and the plasma were exposed to a thermal gradient. There, the cloud convections and dust waves were observed. Analysis by tracking the microparticles’ trajectories showed that the vortices were induced by thermal creep, a gas flow that commonly occurs in gases with low pressures at inhomogeneously heated solid interfaces. This effect has driven a gas convection which in turn caused the convection of the microparticle cloud.
PubDate: 2023-02-27
DOI: 10.1007/s12217-023-10038-z
|
Hybrid journal (It can contain Open Access articles)
