Earth Gravity Research Articles

Gravity data reduction, Bouguer anomaly, and gravity disturbance

Each point on the earth has a gravity and gravity potential value. Surfaces formed by connecting points with equal gravity potential values are called equipotential surfaces or level surfaces. Determination of gravity field of the earth and the geoid which is one of the earth’s equipotential surfaces is very important for physical geodesy. Gravity values measured on the physical earth are not directly included in studies; firstly, they must be converted into gravity anomalies. For this, in this study precise leveling, gravity and GPS measurements were made in the field. Heights (H) with precise leveling measurements, gravity values (g) with gravity measurements and geographical latitudes (j) with GPS measurements were recorded. Then, gravity reductions (free-air, Bouguer) were calculated at the points. The actual gravity g measured on Earth is not immediately directly comparable to the normal gravity of the ellipsoid surface. Gravity values must be reduced to the geoid. Since there are masses outside the geoid, reduction methods differ according to the way these topographic masses are handled. Bouguer gravity anomalies and gravity disturbances are derived. The gravity anomaly (Dg) is defined as the scalar difference between the Earth’s gravity on the geoid and normal gravity on the surface of the reference ellipsoid. Gravity disturbance (dg) is defined as the difference between the actual gravity magnitude measured on Earth and its equivalent normal gravity in the normal gravity field for the same point. The changes and magnitudes of the calculated quantities are compared. Changes such as the observed gravity and height data, observed gravity changes versus calculated normal gravity changes, normal gravity on ellipsoid versus geographic latitude, observed gravity changes versus latitude changes, Bouguer gravity anomaly and gravity disturbance versus latitude and elevation, free-air reduction and Bouguer gravity reduction versus latitude and elevation have been investigated.

The Effects of Taheri Consciousness Fields on the Growth of Escherichia Coli BL21 and Absorption of Lead Heavy Metal by Saccharomyces Cerevisiae in Altered Gravity Conditions

In previous experiments, the growth of different microorganisms under the influence of T-Consciousness Fields (TCFs) was investigated. These fields with non-material and non-energetic properties can have traceable effects on the system under study, and it has been determined that they are different from magnetic, electric, and gravity fields. This study aims to investigate the effects of T-Consciousness Fields on the growth of Escherichia coli (E. coli) strain BL21 as a prokaryotic model organism under microgravity (MG) conditions and also to investigate the bioabsorption behavior of the heavy metal lead by Saccharomyces Cerevisiae, a eukaryotic model, in MG and Earth’s gravity (1G). In these experiments, which were conducted separately, samples without the influence of T-Consciousness Fields were considered as controls, and the duration of the experiment was 24 hours. First, bacterial growth was evaluated by measuring optical density at 600 nm (OD600). The results showed that the microgravity environment increased the growth of bacteria by about 1.4% compared to the earth's gravity (1G). While under the influence of T-Consciousness Fields, no significant difference was observed between MG and 1G samples. In the second study, the inductively coupled plasma mass spectrometry (ICP-MS) technique was used to evaluate heavy metal absorption. The results showed that yeast was able to absorb heavy metal in both gravities and MG environment increasing the absorption significantly and about 13.5% compared to Earth’s gravity. Although the effect of TCFs on the MG sample was not statistically significant, it significantly reduced the absorption of lead metal by about 9% in the conditions of the earth's gravity. In conclusion, the microgravity environment increased the growth of this strain of E. coli bacteria, and the application of T-Consciousness Fields inhibited this growth induction. Also, these fields affected the eukaryote model differently in 1G and MG gravity. It is suggested to investigate the effect of TCFs on the behavior of prokaryotic and eukaryotic organisms under microgravity stress in further studies.

Investigating the Effects of Taheri Consciousness Fields in Microgravity Conditions on Living Organisms and Inanimate Materials

Prior studies have demonstrated through numerous laboratory experiments that TCFs possess a non-physical nature and can exert an influence on the matter and energy of the studied system. In this issue, researchers have engaged in the design and implementation of a comprehensive set of studies where they established microgravity conditions in laboratory settings by creating standard conditions in the field of aerospace sciences. Utilizing precise and global tools in this domain, these studies were conducted on various living organisms, such as human natural and cancerous cells, Escherichia coli bacteria, yeast, wheat plants in the early stages of growth, and materials (pure iron atoms). In these experiments, the effectiveness of T-Consciousness under microgravity conditions was meticulously and repetitively examined compared to control conditions. The results of these experiments not only confirm the entirely independent and distinct nature of these fields from the recognized physical force of gravity but also indicate that TCFs enhance the vitality and survival of cells under microgravity stress. Moreover, they bring the behavior of microorganisms and even the properties of materials closer to conditions under Earth's normal gravity. These observations substantiate the adaptability of information indices and the formation of a novel state under microgravity conditions, enabling the possibility of survival.

Shell-Based Finite Element Modeling of Herøysund Bridge in Norway

This paper thoroughly examines the application of the Finite Element Method (FEM) to the numerical modal analysis of Herøysund Bridge, focusing on the theoretical backdrop, the construction process, and FEM techniques. This work examines the specific applied FEM approaches and their advantages and disadvantages. This Herøysund Bridge analysis employs a two-pronged strategy consisting of a 3D–solid model and a shell model. To forecast the physical behavior of a structure, assumptions, modeling methodologies, and the incorporation of specific components such as pillars are applied to both approaches. This research also emphasizes the importance of boundary conditions, examining the structural effects of standard Earth gravity, a post-tensioned load, and a railing and asphalt load. The Results section thoroughly explores the mode shapes and frequencies of the 3D–solid and shell models. The conclusion of this work includes findings obtained from the study, implications for Herøysund Bridge, and a comparison of both modeling strategies. It also incorporates ideas for future research and guides employing FEM 3D–solid and shell methods to design and construct more efficient, resilient, and durable bridge structures.

Stress Analysis and Structural Improvement of LNG Tank Container Frames under Impact from Railway Transport Vehicles

As the stress of the frame, especially the bottom side rail supports and bottom inclined supports, of a traditional LNG tank container could be significantly greater than its allowable stress, and the container cannot meet the strength requirement of the specification when it is impacted by a transport vehicle during railway transportation, three improved frame structures were suggested, which removed or changed the side rails or bottom inclined supports; the stress and deformation of these improved frames and the tank container were analyzed using the finite element method under the impact test. The results show that all three improved frames can meet the strength requirement, i.e., the maximum Mises stress is less than the allowable stress and the deformation requirement of the diagonal length difference is less than the allowable value, meaning that the tank containers with improved frames can pass the impact test. Moreover, for the FRP support rings and impact side heads, although the maximum values are different, they are still less than the respective allowable stresses. In addition, the maximum value of the middle cross section of the outer vessel in the direction of gravity does not increase with the change in the frame, and the deformation of the outer vessel remains within the elastic range. Therefore, the improvements of the frames have little effect on the stress and deformation of the other components of the tank container, in particular, the inner vessel and outer vessel. Compared to the frame of the traditional tank container, removing the side rails partially or completely can reduce the weight of the frame by 17.99% and 38.34%, respectively, greatly reducing manufacturing and transportation costs. It can also reduce the maximum Mises stress by 38.89% and 39.24% and the maximum diagonal difference by 57.95% and 61.16%.

Improvement of density inversion efficiency with projected gradient method: Application to FTG data

With the development of instruments for measuring Earth's gravity gradient tensor, full tensor gravity (FTG) data can be obtained validly and accurately. The highly precise performance of FTG data ensures that they can play an important role in many domains. Generally, FTG data can be acquired from airborne platform, and large-scale data can be obtained by long term observations. For this type of data, research methods for large data processing are very important. Three-dimensional data inversion is an effective and significant method for the quantitative interpretation of FTG data, which has received much attention. Large-scale data inversion is inevitable, and may consume large amounts of time with increase in the amount of data and model parameters. The main aim of this study is to improve the calculation efficiency of FTG data inversion compared with general conjugate gradient (CG) method. Accordingly, an improved gradient method with projections onto a convex set (the projected gradient method) was applied to accelerate the recovery rate of the sub-surface rock density, and a corresponding preconditioning factor was introduced to further improve the calculation efficiency of inversion. This new projected gradient method can improve the calculation efficiency of large amounts of FTG data, which is very necessary for practical application of FTG data. The application of synthetic FTG data with Gaussian noise and the real data demonstrated the feasibility and application value of the proposed inversion method.

Vascular smooth muscle cell-specific miRNA-214 deficiency alleviates simulated microgravity-induced vascular remodeling.

The human cardiovascular system has evolved to accommodate the gravity of Earth. Microgravity during spaceflight has been shown to induce vascular remodeling, leading to a decline in vascular function. The underlying mechanisms are not yet fully understood. Our previous study demonstrated that miR-214 plays a critical role in angiotensin II-induced vascular remodeling by reducing the levels of Smad7 and increasing the phosphorylation of Smad3. However, its role in vascular remodeling evoked by microgravity is not yet known. This study aimed to determine the contribution of miR-214 to the regulation of microgravity-induced vascular remodeling. The results of our study revealed that miR-214 expression was increased in the forebody arteries of both mice and monkeys after simulated microgravity treatment. Invitro, rotation-simulated microgravity-induced VSMC migration, hypertrophy, fibrosis, and inflammation were repressed by miR-214 knockout (KO) in VSMCs. Additionally, miR-214 KO increased the level of Smad7 and decreased the phosphorylation of Smad3, leading to a decrease in downstream gene expression. Furthermore, miR-214 cKO protected against simulated microgravity induced the decline in aorta function and the increase in stiffness. Histological analysis showed that miR-214 cKO inhibited the increases in vascular medial thickness that occurred after simulated microgravity treatment. Altogether, these results demonstrate that miR-214 has potential as a therapeutic target for the treatment of vascular remodeling caused by simulated microgravity.

Experimental Investigation of Critical Heat Flux of Nucleate Pool Boiling of Water and Nanofluid on Platinum Wire Under Hypergravity and Earth Gravity

Experimental Investigation of Critical Heat Flux of Nucleate Pool Boiling of Water and Nanofluid on Platinum Wire Under Hypergravity and Earth Gravity

Increased H3K9me3 and F-Actin Reorganization in the Rapid Adaptive Response to Hypergravity in Human T Lymphocytes.

Our study explored the impact of hypergravity on human T cells, which experience additional acceleration forces beyond Earth's gravity due to various factors, such as pulsatile blood flow, and technology, such as high-performance aircraft flights or spaceflights. We investigated the histone modifications Histone 3 lysine 4 and 9 trimethylation (H3K4me3 and H3K9me3, respectively), as well as the structural and cytoskeletal organization of Jurkat T cells in response to hypergravity. Histone modifications play a crucial role in gene regulation, chromatin organization and DNA repair. In response to hypergravity, we found only minimal changes of H3K4me3 and a rapid increase in H3K9me3, which was sustained for up to 15 min and then returned to control levels after 1 h. Furthermore, rapid changes in F-actin fluorescence were observed within seconds of hypergravity exposure, indicating filament depolymerization and cytoskeletal restructuring, which subsequently recovered after 1 h of hypergravity. Our study demonstrated the rapid, dynamic and adaptive cellular response to hypergravity, particularly in terms of histone modifications and cytoskeletal changes. These responses are likely necessary for maintaining genome stability and structural integrity under hypergravity conditions as they are constantly occurring in the human body during blood cell circulation.

Space debris environment engineering model 2019: Algorithms improvement and comparison with ORDEM 3.1 and MASTER-8

As an essential tool for realistic description of the current or future debris environment, the Space Debris Environment Engineering Model (SDEEM) has been developed to provide support for risk assessment of spacecraft. In contrast with SDEEM2015, SDEEM2019, the latest version, extends the orbital range from the Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) for the years 1958–2050. In this paper, improved modeling algorithms used by SDEEM2019 in propagating simulation, spatial density distribution, and spacecraft flux evaluation are presented. The debris fluxes of SDEEM2019 are compared with those of three typical models, i.e., SDEEM2015, Orbital Debris Engineering Model 3.1 (ORDEM 3.1), and Meteoroid and Space Debris Terrestrial Environment Reference (MASTER-8), in terms of two assessment modes. Three orbital cases, including the Geostationary Transfer Orbit (GTO), Sun-Synchronous Orbit (SSO) and International Space Station (ISS) orbit, are selected for the spacecraft assessment mode, and the LEO region is selected for the spatial density assessment mode. The analysis indicates that compared with previous algorithms, the variable step-size orbital propagating algorithm based on semi-major axis control is more precise, the spatial density algorithm based on the second zonal harmonic of the non-spherical Earth gravity (J2) is more applicable, and the result of the position-centered spacecraft flux algorithm is more convergent. The comparison shows that SDEEM2019 and MASTER-8 have consistent trends due to similar modeling processes, while the differences between SDEEM2019 and ORDEM 3.1 are mainly caused by different modeling approaches for uncatalogued debris.

Effect of leakage source condition on the unignited hydrogen released issuing through a horizontal realistic pipeline geometry

An unignited gas release experiment system for the schlieren visualization and concentration quantitative measurement is designed and built to investigate the diffusion and concentration distribution features of turbulent hydrogen jets issuing from a realistic pipeline geometry. Helium is used in place of hydrogen for safety reasons. The spatial and temporal evolution of the asymmetry of turbulent helium jets was studied. The influence mechanisms of the volumetric flow rate (Q), the ratio of orifice diameter to the inner diameter of pipeline (R), and the angle between the normal of the leakage orifice and the opposite direction of gravity (θ) on the asymmetric concentration distribution are revealed. The experimental results show that the diffusion angle (α) and the inclination angle (β) of the turbulent helium jet are the largest when Q is 15 SLPM, R is 0.3, and θ is 0°, and the asymmetric feature of the turbulent helium jet is obvious. As the Q increased, the slope k of the inverse helium concentration (1/volume fraction) and a scaled distance L (L = (x/d)·(ρa/ρ0)1/2) became small. The increase of Q aggravated the concentration attenuation caused by the volumetric flow rate and the asymmetry jet. As R increased, the slope k of the inverse helium concentration and a scaled distance L first decreased and then increased. The slope k got the minimum value when R was 0.3. The downward movement of the leakage orifice position increased the turbulent intensity near the leakage orifice. This work can provide theoretical support for accident prevention and emergency treatment of hydrogen leakage accidents in long-distance pipeline low-pressure hydrogen transportation.

A Simulation Study for Future Geodetic Satellites Tracked by Satellite Laser Ranging

AbstractSatellite laser ranging (SLR) measurements play a key role in determining global geodetic parameters, such as station coordinates, geocenter motion, low‐degree Earth's gravity field parameters, and Earth rotation parameters. Observations to two LAser GEOdynamics Satellites (LAGEOS) and two Etalon satellites provide operational standard products and contribute to the realization of the scale and the origin of the International Terrestrial Reference Frame (ITRF). Currently, an extension of the ITRF realizations is being considered with the inclusion of the Laser Relativity Satellite (LARES). In July 2022, the LARES‐2 satellite was launched with the main purpose to verify fundamental physics, especially the Lense‐Thirring effect emerging from General Relativity. We simulate orbits and observations for the LARES‐2 satellite, as well as the LARES‐like satellites, which complement the current constellation of LAGEOS‐1/‐2 and LARES‐1/‐2 using the butterfly configuration. We assess the impact of the observations to satellites with different orbital parameters on the determination of global geodetic parameters. We show that placing a satellite in a retrograde orbit (against the Earth's rotation), can improve the quality of the global geodetic parameters. The solution based on LAGEOS‐1/‐2 + LARES‐1/‐2 + a satellite supplementary to LAGEOS‐2 in a retrograde orbit achieves the 3D mean error at the level of 1.62 mm for the station coordinates, and mean errors of 0.7, 0.7, and 1.3 mm for the X, Y, and Z geocenter components, respectively, bringing us closer to fulfilling the requirements established by the Global Geodetic Observations System (GGOS) of 1 mm accuracy for the reference frame stability.

Dynamical properties and detectability of the magneto-thermal instability in the intracluster medium

Context.Amongst the many plasma processes potentially relevant to the dynamics of the intracluster medium (ICM), turbulence driven at observable scales by internal magnetised buoyancy instabilities such as the magneto-thermal instability (MTI) stands out in the outskirts of the ICM, where the background temperature decreases with the radius.Aims.We characterise the statistical properties of MTI turbulence in the ICM and assess whether such large-scale magnetised plasma dynamics would be detectable with the future X-ray calorimeter X-IFU on board Athena.Methods.We made use of scaling laws previously derived to phenomenologically estimate the observable turbulent saturation levels and injection length of MTI turbulence for different ICM thermodynamic profiles, and performed a numerical magnetohydrodynamic simulation of the dynamics with Braginskii heat and momentum diffusion. As a prospective exercise, we used the simulation to virtually observe MTI turbulence through the X-IFU.Results.In bright enough regions amenable to X-ray observations, the MTI drives mild turbulence up to ∼5% and ∼100 km s−1(root-mean square temperature fluctuation and velocity). However, the measurable integrated temperature fluctuation and line-of-sight velocity fields, the latter being essentially the azimuthal velocity component in cluster haloes, hardly exceed 1% and 10 km s−1, respectively (root-mean square). We show that such moderate signals would be difficult to detect with upcoming X-ray telescopes. We also find that MTI turbulence is anisotropic in the direction of gravity and develops at scales ≳0.2 Mpc. If the fluctuation intensities were to be stronger than the current theoretical estimates, MTI fluctuations would be detectable and their anisotropy discernible with the X-IFU.Conclusions.Finding direct signatures of magnetised plasma dynamics in the ICM, even at observable scales typical of the fluid MTI, remains challenging. This study only marks a first step in this direction. Several numerical and observational strategies are discussed to make further progress in the future.

A new method for finding the proper initial conditions in passive locomotion of bipedal robotic systems

In this paper, the walking motion of a biped robot consisting of upper and lower body members (arms, legs, upper trunk and neck) on an inclined surface is analyzed kinematically and dynamically. Some of the challenges faced by this research include the dual-phase dynamics that govern the periodic gait of this robotic system and the consideration of all the body parts that are involved in the walking motion; which make it extremely difficult to derive the kinetic equations of such robotic systems. To deal with these challenges, the Gibbs-Appell formulation and the Newton's impact laws are employed to derive the most general form of the system's dynamic equations in the swing and transient phases of motion. Subsequently, by using the obtained motion equations and implementing a systematic procedure, we achieve an eigenvalue problem. By solving this problem, the suitable initial conditions that are necessary for the passive gait of this biped robot on a sloping surface are determined. By considering the obtained initial conditions as well as the dynamic response of the system to the Earth's gravity, we describe a general method for designing a biped robot's walking trajectory on an inclined surface. The most important feature of the designed trajectory is its close agreement with the trajectory followed by a biped robot walking passively down a sloping ramp. This close match between the said trajectories enables us to guide the robot in tracking a desired path by applying very small control torques to the robot joints at the start of each step. This claim is corroborated by the simulations carried out for a biped walking robot composed of 6 rigid links, in which the control torques that are applied to the actuated robot joints are obtained by employing a feedback linearization method and via a designed LQR controller.

Imaging Lunar Craters with the Lucy Long Range Reconnaissance Imager (L’LORRI): A Resolution Test for NASA's Lucy Mission

NASA's Lucy mission is designed to better understand the unique population of Trojan asteroids. Trojans were probably captured in Jupiter's L4 and L5 points early in the solar system's evolution and little altered since then. A critical investigation of Lucy is to use its highest-resolution camera, the Lucy Long Range Reconnaissance Imager (L’LORRI), to image Trojans’ surfaces to understand their geology and impact crater populations. Through crater statistics, the population of smaller bodies that produced those impacts, relative age differences across the bodies, and other comparative investigations between bodies can be studied. Mapping the crater population to the minimum diameters needed to achieve Lucy's objectives might require image subsampling and deconvolution (“processing”) to improve the spatial resolution, a process whereby multiple, slightly offset images are merged to create a single, better-sampled image and deconvolved with L’LORRI's point-spread function. Lucy's first Earth Gravity Assist (EGA1) provided an opportunity to test this process's accuracy using L’LORRI images of the Moon, whose crater population is well characterized and therefore provides ground-truth testing. Specifically, the lunar crater imaging by L’LORRI during EGA1 allowed us to compare crater statistics derived from raw and processed L’LORRI images with ground-truth statistics derived from higher-resolution lunar imaging from other missions. The results indicate the processing can improve impact crater statistics such that features can be identified and measured to ≈70% the diameter that they can otherwise be reliably mapped on native L’LORRI images. This test's results will be used in the observation designs for the Lucy flyby targets.

Prediction technique for flow boiling heat transfer and critical heat flux in both microgravity and Earth gravity via artificial neural networks (ANNs)

This study is part of the Flow Boiling and Condensation Experiment (FBCE) and utilizes flow boiling data collected in both microgravity onboard the International Space Station (ISS) and Earth gravity at different channel orientations. The goal is to develop a prediction technique for heat transfer and critical heat flux (CHF) for flow boiling in both microgravity and Earth gravity using artificial neural networks (ANNs). The working fluid, n-perfluorohexane or FC-72, flows through a rectangular channel of 114.6 mm heated length, 2.5 mm heated width, and 5.0 mm unheated height with either one or two walls heated. The consolidated FBCE database for heat transfer coefficient comprises 29,226 datapoints spanning a mass velocity of 173 – 3200 kg/m2s, pressure of 102 – 238 kPa, subcooling of 0 – 44°C, and thermodynamic equilibrium quality of -0.60 – 0.95 (spanning from highly subcooled to high-quality saturated boiling). Following a statistical analysis of various input parameters relevant to flow boiling and optimization of key model parameters, a fully connected feed-forward ANN is developed to predict Nutp. It predicts the entire test database with an overall mean absolute error (MAE) of just 7.99% with consistent and accurate predictions in each subset. Similarly, 641 CHF datapoints from FBCE were consolidated into a database spanning a mass velocity of 99 – 3212 kg/m2s, inlet pressure of 97 – 239 kPa, inlet subcooling of 0 – 46°C, inlet thermodynamic equilibrium quality of -0.61 – 0.86, and CHF values of 4 – 54 W/cm2. A separate ANN is developed by following the same methodology as heat transfer, and it predicts dimensionless CHF, BoCHF, with an overall MAE of just 12.05%. Existing seminal correlations are assessed for subsets of the two consolidated FBCE databases, and the ANNs are shown to have better accuracies in each subset of the database. The ANNs’ high prediction accuracy, in conjunction with their ability to predict physical parametric trends in previously unseen data, shows their potential as prediction tools for both heat transfer and CHF for flow boiling in microgravity and Earth gravity.

Investigation on the Erosion Characteristics of Liquid–Solid Two-Phase Flow in Tee Pipes Based on CFD-DEM

Tee pipes are widely utilized in pipeline transportation, especially in subsea production systems and the chemical industry. The purpose of this research is to study the influences of gravity direction, conveying parameters and particle properties on the erosion distribution in tee junctions. Investigation using the CFD-DEM coupled method is conducted on the flow mechanisms and erosion characteristics in a tee junction under different flow conditions. Firstly, numerical calculations of liquid–solid two-phase flow in a vertical cylindrical pipe are performed, and the comparison between simulation results and experimental results is carried out. Then, the verified lift and erosion models are used for the numerical calculations of tee pipes. Flow mechanisms and erosion characteristics are numerically investigated through analysis of the velocity profiles, streamlines, and erosion contours. The results indicate that the gravity direction has a nonnegligible influence on the cross-sectional velocity profiles, particularly under the condition of high velocity and high particle concentration. The region with the maximum erosion rate occurred at the branch pipes, about three fourths of the pipe diameter away from the tee junction.

The promises and pitfalls of precision: random and systematic error in physical geodesy, c. 1800–1910

ABSTRACT This article discusses the ways in which nineteenth-century geodesists reflected on precision as an epistemic virtue in their measurement practice. Physical geodesy is often understood as a quintessential nineteenth-century precision science, stimulating advances in instrument making and statistics, and generating incredible quantities of data. Throughout most of the nineteenth century, geodesists indeed pursued their most prestigious research problem – the exact determination of the earth’s polar flattening – along those lines. Treating measurement errors as random, they assumed that remaining discordances could be overcome by manufacturing better instruments and extending statistical analysis to a larger amount of data. In the second half of the nineteenth century, however, several German geodesists developed sophisticated methodological critiques of their discipline, in which they diagnosed a too-narrow focus on precision among their peers. On their account, geodesists urgently needed to identify and anticipate the causes of the remaining measurement errors that arose from the earth’s little understood interior constitution. While mostly overlooked in the literature, these critiques paved the way for many empirical successes in late nineteenth- and early twentieth-century geodesy, including the first convergent measurements of the earth’s polar flattening.

Comparation of Model and Experimental Results of Elastoplastic Structure Loaded with Bending Moment and Torsion

Experimental testing and numerical analysis were conducted on steel structure with 20 × 20 mm rectangular section loaded with combination of bending moment (M) and torsion (T), used to validated the previous study. Specimen used in the research was cantilever grid beam with fixed constraint at the end of the beam. The specimen was incrementally loaded parallel with gravity direction until failure occurred. Load, displacement and strain at observed point were recorded to analyze failure criteria based on Von Mises criteria. Numerical model using DIANA was used to analyze further the internal forces and stress distribution at the beam structure. 3D solid model was used for the numerical analysis in order to represent the experimental results. Experimental and numerical analysis results were in good agreement compared to the previous study. The experimental strain data shows that plastic joints formed gradually in one location and followed in other locations. Analysis using Von Mises criteria shows that the yield of the structure was significantly affected by bending with proportion of ± 90%. Numerical model located the same position of plastic joints compared to experimental. The stress distribution shows that the maximum stress is located at the vertical outer side of section which indicated that the bending stress is dominant.

Fluid and Bubble Flow Detach Adherent Cancer Cells to Form Spheroids on a Random Positioning Machine.

In preparing space and microgravity experiments, the utilization of ground-based facilities is common for initial experiments and feasibility studies. One approach to simulating microgravity conditions on Earth is to employ a random positioning machine (RPM) as a rotary bioreactor. Combined with a suitable low-mass model system, such as cell cultures, these devices simulating microgravity have been shown to produce results similar to those obtained in a space experiment under real microgravity conditions. One of these effects observed under real and simulated microgravity is the formation of spheroids from 2D adherent cancer cell cultures. Since real microgravity cannot be generated in a laboratory on Earth, we aimed to determine which forces lead to the detachment of individual FTC-133 thyroid cancer cells and the formation of tumor spheroids during culture with exposure to random positioning modes. To this end, we subdivided the RPM motion into different static and dynamic orientations of cell culture flasks. We focused on the molecular activation of the mechanosignaling pathways previously associated with spheroid formation in microgravity. Our results suggest that RPM-induced spheroid formation is a two-step process. First, the cells need to be detached, induced by the cell culture flask's rotation and the subsequent fluid flow, as well as the presence of air bubbles. Once the cells are detached and in suspension, random positioning prevents sedimentation, allowing 3D aggregates to form. In a comparative shear stress experiment using defined fluid flow paradigms, transcriptional responses were triggered comparable to exposure of FTC-133 cells to the RPM. In summary, the RPM serves as a simulator of microgravity by randomizing the impact of Earth's gravity vector especially for suspension (i.e., detached) cells. Simultaneously, it simulates physiological shear forces on the adherent cell layer. The RPM thus offers a unique combination of environmental conditions for in vitro cancer research.