Component Of Gravity Research Articles

The Level of Markers Stimulating Growth Factor 2 (ST2), N-Terminal Prohormone of Brain Natriuretic Peptide (NT-proBNP), and D-Dimer in Healthy Volunteer Testers in 21-Day Head-Down -6° Tilt Bed Rest as a Model of Hypodynamia.

The paper presents an analysis of the proteomic composition in relation to both the risk of thrombosis and changes in the state of cardiomyocytes associated with the risk of cardiac fibrosis and heart failure. We examined 12 practically healthy male volunteers exposed to head-down -6° tilt bed rest (HDBR) for 21 days. The revealed decrease in the level of stimulating growth factor 2 (ST2) on days 10 and 21 relative to the initial values (background; 5 days before HDBR) indicated a decrease in the myocardial load and cardiomyocyte extensibility. The level of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) increased on day 2, decreased on days 10 and 21 of HDBR relative to the background levels, and returned to baseline values after the recovery period (5 days after HDBR). The revealed changes in the level of NT-proBNP reflected the increase in circulating blood volume corresponding to HDBR duration and the role of the gravity component in increasing the functional load on the myocardium. Unchanged blood level of D-dimer at all points of the study indicates that there is no risk of thrombosis under the conditions of this study.

Computational comparison of approaches based on geometrical orientation and gravity components in analysing the melting behaviour of thermal energy storage system

Computational comparison of approaches based on geometrical orientation and gravity components in analysing the melting behaviour of thermal energy storage system

A switched-gain nonlinear observer for estimation of thoracoabdominal displacements and detection of asynchrony

This paper develops and evaluates a wearable sensor-based system for the estimation of three-dimensional thoracoabdominal displacements and the detection of respiratory asynchrony between chest and abdomen. Such estimation is useful for a number of respiratory diagnosis applications, including detection of paradoxical breathing, quantification of tidal volume, and decision-support for initiation of, or weaning from, mechanical ventilation. The use of inertial sensors on the body to estimate respiratory displacements is challenging due to the tilting of the body that occurs with breathing, causing continuous changes in the gravity component at the same frequency as the breathing frequency. A method to estimate the front-to-back and side-to-side tilt angles is developed using a nonlinear observer. Due to the complex multivariable nonlinear measurement functions involved, a switched gain nonlinear observer is found to be necessary. The global stability of the observer is analyzed using Lyapunov analysis. Respiratory asynchrony is evaluated using Lissajous curves and a cross correlation phase angle calculation method. Example experimental results are presented using data from three subjects at various breathing frequencies, tidal volumes, and inspiratory resistances. Displacement estimates are found to be typically within ± 1 mm compared to a gold standard reference for most data sets. Phase angles are found to increase monotonically with inspiratory resistive or elastic loading.

A gravitational eye: a method for extracting maximum information from gravitational potentials

Gravity measurements have uses in a wide range of fields including geological mapping and mine-shaft inspection. The specific application under consideration sets limits on the survey and the amount of information that can be obtained. For example, in a conventional gravity survey at the Earth’s surface a gravimeter is translated on a two-dimensional planar grid taking measurements of the vertical component of gravity. If, however, the survey points cannot be chosen so freely, for example if the gravimeter is constrained to operate in a tunnel where only a one-dimensional line of data could be taken, less information will be obtained. To address this situation, we investigate an alternative approach, in the form of an instrument which rotates around a central point measuring the gravitational potential or its radial derivative on the boundary of a sphere. The ability to record additional components of gravity by rotating the gravimeter will give more information than obtained with a single measurement traditionally taken at each point on a survey, consequently reducing ambiguities in interpretation. We term a device which measures the potential, or its radial derivatives, around the surface of a sphere a gravitational eye. In this article we explore ideas of resolution and propose a thought experiment for comparing the performance of diverse types of gravitational eye. We also discuss radial analytic continuation towards sources of gravity and the resulting resolution enhancement, before finally discussing the possibility of using cold-atom gravimetry and gradiometry to construct a gravitational eye. If realised, the gravitational eye will offer revolutionary capability enabling the maximum information to be obtained about features in all directions around it.

Cosmological implications of non-minimally coupled f(Q) gravity

We experience some challenges in general gravitational theory owing to Einstein to explain late time acceleration of universe. To address this issue, geometric components of gravity have been modified in quite a few occasions to have a more general structure with some freedom. One such approach is to change the geometric components of gravity where gravitational interaction is denoted by Q, Q being the non-metricity. In our work, we have considered symmetric teleparallel gravity i.e, modified the geometry with the help of non-metricity Q or [Formula: see text] gravity. We have considered a specific form of [Formula: see text] which is nothing but the linear combination of Q and [Formula: see text], [Formula: see text], where Q is coupled with Lagrangian matter. Forming the autonomous system from governing equations and then solving it, we have tried to analyze the nature of universe using dynamical system analysis. We have studied the behavior of the universe under several circumstances. Then, we have studied the stability around critical points and considering the recent observational data available for some cosmological parameters, feasible solutions are noted which depict late time acceleration. We can see that [Formula: see text] gravity model can be considered as an alternative model to [Formula: see text]CDM model.

Thermal and hydraulic characteristics analysis of horizontal lead-bismuth reactor assembly based on sub-channel analysis code

In this paper, the self-developed subchannel analysis program SACOS-PB was used to analyze the thermal hydraulic characteristics of 127 rods in horizontal lead-bismuth reactor under steady state and typical ocean transient conditions. The results of the steady-state analysis showed that the coolant flow and temperature of the vertical assembly were symmetrically distributed, the coolant flow of the horizontal assembly gradually increased along the gravity direction, the temperature rose first and then fell, and the peak coolant temperature of the cross-sectional channel was about 365 °C. Three typical ocean transient operating conditions, inclined, undulating and swing, were also carried out. The results showed that the maximum temperature of the coolant at the exit of the assembly increased with the increase of the transverse heeling angle and the decrease of the trim angle after the incline motion changes the gravity component. Under the undulating and swing conditions, the coolant hydrothermal parameters fluctuated periodically, and the parameter fluctuation period is 10s in line with the oceanic conditions. In the above transient conditions, the peak coolant temperature at the assembly outlet increases and exceeds 365 °C. Compared with the pitching motion on the Y-axis, the rolling and tumbling motion on the X-axis had a significant effect on the coolant flow rate and temperature distribution. The calculation results can provide support for the analysis study of the safety characteristics of lead-bismuth power units under marine conditions.

The relationship between GRACE gravity and the seismic b-value: a case study of the Northern Chile Triple Junction (25° S–40° S)

SUMMARY The northern Chile Triple Junction (CTJ) is characterized by the ongoing subduction of the Nazca plate beneath the South American plate. The geological structures within the subduction zone undergo complex changes, resulting in significant tectonic activities and intense seismicity along the western margin of South America. Based on the Gravity Recovery and Climate Experiment (GRACE) data and earthquake catalogues, this study selects the northern CTJ area (25° S–40° S, 75° W–65° W) as the research object, adopts the mathematical methods of independent component analysis (ICA) and principal component analysis (PCA) to separate the earthquake-related signals within the GRACE data, and fits the changes of seismic b-values through the frequency–magnitude relationship. The characteristics of gravity changes before and after seismic events, the seismic activity parameter b-values, and the relationship between the gravity signals and b-values are discussed. The results show that mathematical methods can effectively extract seismic-related gravity components from the GRACE data. ICA, compared to PCA, provides better results in capturing the temporal variations associated with b-value time-series, which exhibit good consistency in long-term trend changes. The average change of b-values in the study area is 0.66 ± 0.003, fluctuating over time. Generally, prior to larger seismic events, b-values tend to decrease. Along the western margin of South America, b-values are low; this aligns with the active tectonic activities between subducting plates. Additionally, a certain correlation between b-values and gravity changes is observed, but due to the influence of tectonic activities, the correspondence between b-values and gravity anomalies may not be consistent across different areas. The b-value is highly consistent with the strain rate model. Low b-values correspond to high strain rates along the western edge of South America, which is in line with the tectonic characteristics of frequent seismic activity in this area. A gradual concentration of gravity anomalies before major earthquakes is observed, accompanied by the gradual accumulation of smaller seismic events. Meanwhile, several months before the two major earthquakes, the spatial distribution of gravity appears to be similar to the coseismic signals, but the nature of its generation remains to be explored. These methods and results not only add to the applications of GRACE in seismic studies but also raise questions for further exploration.

Investigation of cladding layer formation in uphill wire laser additive manufacturing on inclined substrate

In wire laser additive manufacturing (WLAM), the position posture of substrate is highly related to the formation process of the cladding layer which will affect the forming quality and service performance of the manufacturing parts. The forming quality of the cladding layer is often difficult to be controlled under the condition of the inclined substrate. Therefore, a three-dimensional dynamic model is established in this paper to investigate the WLAM process on inclined substrate. The influence of the inclined substrate on the forming quality of the cladding layer is analyzed from the evolution of wire molten metal transfer process and oscillation behaviors of the molten metal in the molten pool. It is found that the backward gravity component plays a major role in promoting the backward oscillation process of the molten metal in the molten pool on inclined substrate. The backward oscillation process of the molten metal is the main factor for the formation of cladding layer with wave morphology. The calculated cladding layer morphology is validated by the experimental results. The proposed model is of great theoretical significance for understanding the molten pool dynamic behaviors of the WLAM process and improving the forming quality of the cladding layer on inclined substrate further.

High-precision 1′ × 1′ bathymetric model of Philippine Sea inversed from marine gravity anomalies

Abstract. The Philippine Sea, located at the edge of the northwestern Pacific Ocean, possesses complex seabed topography. Developing a high-precision bathymetric model for this region is of paramount importance, as it provides fundamental geoinformation essential for Earth observation and marine scientific research, including plate motion, ocean circulation, and hydrological characteristics. The gravity–geologic method (GGM), based on marine gravity anomalies, serves as an effective bathymetric prediction technique. To further strengthen the prediction accuracy of conventional GGM, we introduce the improved GGM (IGGM). The IGGM considers the effects of regional seafloor topography by employing weighted averaging to more accurately estimate the short-wavelength gravity component, along with refining the subsequent modeling of long-wavelength gravity component. In this paper, we focus on seafloor topography modeling in the Philippine Sea based on the IGGM, combining shipborne bathymetric data with the Scripps Institution of Oceanography (SIO) V32.1 gravity anomaly. To reduce computational complexity, the optimal parameter values required for IGGM are first calculated before the overall regional calculation, and then, based on the terrain characteristics and distribution of sounding data, we selected four representative local sea areas as the research objects to construct the corresponding bathymetric models using GGM and IGGM. The analysis indicates that the precision of the IGGM models in four regions is improved to varying degrees, and the optimal calculation radius is 2′. Based on the above finding, a high-precision 1′×1′ bathymetric model of the Philippine Sea (5–35° N, 120–150° E), known as the BAT_PS model, is constructed using IGGM. Results demonstrate that the BAT_PS model exhibits a higher overall precision compared to the General Bathymetric Chart of the Oceans (GEBCO), topo_25.1, and DTU18 models at single-beam shipborne bathymetric points.

Computational study of magneto-convective flow of aqueous-Fe3O4 nanoliquid in a tilted cylindrical chamber partially layered by porous medium: Entropy generation analysis

In various industrial applications, the main objective is to enhance thermal efficiency by minimizing the generation of entropy. Specifically, achieving optimal thermal efficiency in a tilted cylindrical chamber poses significant challenges due to the combined effects of tangential and normal gravity components. Our study focuses on the flow dynamics, thermal transport, and entropy generation of Fe3O4/H2O nanoliquid within a cylindrical annular enclosure by incorporating the synergistic effects of magnetic force, geometric inclination angle, and thickness of the porous region. The Brinkman–Forchheimer-extended Darcy model for ferrofluid motion and the one-equation model for heat transfer are applied in the porous region, while the conventional Navier–Stokes and energy equations are used in the fluid-only region. A series of computations is performed for various key parameters, such as Hartmann number (0≤Ha≤60), Darcy number (10−5≤Da≤10−1), porous layer thickness (0.1≤ε≤0.9), and angle of inclination (−60°≤γ≤60°). Our results reveal that the heat transport rate is enhanced by 48.6% with an increase in the Darcy number from 10−5 to 10−1. Moreover, the flow circulation and heat transport can be optimized by tilting the enclosure anticlockwise. It has been found that 91.8% of flow strength can be enhanced by rotating the enclosure from −60° to 60°. Finally, this study suggests that the inclination angle of 30° and a porous layer thickness of 0.3 emerge as the ideal configuration to obtain optimal performance, particularly for lower Hartmann and higher Darcy numbers. Our findings will provide insight into optimizing thermal processes in nanoliquid-filled enclosures subjected to magnetic force.

Ridge instability in dense suspensions caused by the second normal stress difference

A dense suspension of the cornstarch flowing on a very inclined wall finally forms some ridge-like patterns of the free surface. The onset of pattern formation is the primary target to elucidate the mechanism. In this work, based on the continuity of fluids and the force balance, we show that the flat free surface is unstable when the second normal stress difference N2 is negatively proportional to shear stress and the gravity component perpendicular to the wall is weak enough. Such instability is inevitable for the growth of a ridge-like surface profile oriented parallel to the flow direction. We use the instability criterion to predict the critical slope angle for the formation of ridge patterns. The estimated critical angle was found to be in agreement with experimental observations for a cornstarch suspension.

Salt rejection/discharge strategies of a reverse-distillation device with a water layer for sustainable solar desalination: From two dimensions to three dimensions

The recently proposed solar-driven reverse-distillation device with a water layer has shown promising potential in solar energy conversion efficiency and impactful advantages in salt rejection by constructing a rapid brine flow driven by gravity/density differences. However, a lack of profound understanding and explanation of the salt-rejection mechanism and accurate salt-discharge regulation strategies may hinder the further improvement of reverse-distillation devices. In this paper, we thoroughly discuss and analyze the mechanism of how gravity affects the internal brine flow and determines the salt rejection/discharge performance while providing comprehensive salt-discharge regulation strategies for feed brine with a wide range of salinities. The results show that only a 4° inclination angle enables the two-dimensional (2D) device with a 1-mm-thick water layer in the dissolution mode to dispose 3.5 wt% brine for 8 h without salt saturation, while the value is also merely 10° for a three-dimensional (3D) device, indicating the realization of the brine flow driven by a small gravity component and demonstrating a strong adaptability for the device. In the salt discharge mode, the ratio of the discharge flow rate to the evaporation rate determines the salt saturation risk. We discuss the salinity distribution of the evaporation surface at varied feed-brine salinities and discharge flow rates, providing a theoretical basis for precisely matching the thermal characteristics and enabling improved design for efficient and sustainable solar-distillation devices. Finally, we discuss the scalability of salt rejection and propose a scheme for scalable water production, which may offer important support for further realizing large-scale sustainable solar desalination by using the reverse-distillation device with a water layer.

Aerobics Arm Movement Trajectory Recognition with Motion Computer Assistance

Abstract Aerobics is an internationally famous fitness and sports competition program. This paper aims to design an aerobics arm movement trajectory recognition method with the assistance of a sports computer to detect aerobics movements in real-time. The study first introduces the Gaussian kernel function based on the Kalman filter pose solution method to construct the aerobics arm GP-SUKF pose solution model. The acceleration data are then coordinate transformed to remove the gravity component of each axis, and the features of the aerobics action trajectory are extracted by combining the time-frequency domain integration method and eliminating the cumulative error. Finally, a support vector machine algorithm based on particle swarm optimization is constructed to classify and identify the features extracted from the trajectory of the extracted aerobics arm. In the simulation experiments, the algorithm in this paper provides more motion trajectory points for the aerobics arm movements. It is closer to the actual value of the wrist movements offered by the OptiTrack system, with the error ranging from 0.02m to 0.04m, and a better tracking effect can be obtained in the case of fast movements. This study can accurately track the trajectory of aerobics arm movements and provide more accurate posture and movement assistance for professional athletes and bodybuilders.

Extraction of gravity components related to W-Sn polymetallic deposits using Bi-dimensional empirical mode decomposition (BEMD) in the Laojunshan Ore Cluster Region, SW China

The Laojunshan ore cluster region is situated at the north Song Chay dome, which is the junction of the Yangtze, the Cathaysia, and the Indo-China Blocks. The north Song Chay dome characterized by the Laojunshan metamorphic core complex is an important ore-forming region for W-Sn-Pb-Zn-In elements related to the Late Cretaceous granitic magmatism. In this paper, the Bi-dimensional empirical mode decomposition (BEMD) is applied to separate gravity components from the original gravity data, combined with the known geological and mineralized information, to explore the relationships between the gravity components and various ore-controlling factors at different depths. Four intrinsic mode functions (IMFs) and a residue are obtained. They may imply the spatial distribution of the geological bodies with featured gravity components at different depths. The results are shown as follows:(1) The low-pass filtering gravity component (BIMF4) implies the deeply buried geological units in the study region. The Cretaceous Laojunshan granitic complex and the Nanwenhe gneissic granite display negative gravity components and weak positive gravity components, respectively. The former is closely related to Sn-Zn-In mineralization, the latter is closely related to W polymetallic deposits. Therefore, the negative gravity components showing the Laojunshan granitic complex are the prospecting targets for deeply buried Sn-Zn-In deposits. The weak positive gravity components displaying the Nanwenhe gneissic granite are the prospecting targets for deeply buried W polymetallic deposits.(2) The band-pass filtering gravity component (BIMF3) implies the geological units at middle depth. The skarn-type Sn-W polymetallic deposits are observed in the transition zones from the positive to the negative gravity components, which coincide with the contact metasomatic zones between the Cretaceous granite and the Cambrian-Devonian carbonate rocks. Some small quartz vein W deposits occur within the Cretaceous Laojunshan granite with negative gravity components, and some layered W deposits occur in the Silurian gneissic granite with a weak positive gravity component.(3) High-pass filtering gravity component (BIMF2) implies geological units at the shallow crust, which shows that most of the deposits (occurrences) are located within the positive gravity component zones. These positive gravity component zones should be ore-finding targets for further prospecting for the undiscovered Sn and W polymetallic deposits.(4) The gravity components separated by BEMD coincide with the spatial distribution of the granites associated with various types of mineralization and alteration zones at different depths, which will give insights for further prospecting for concealed ore bodies in this study region.

2D fast Fourier transform analytical solutions in all space for all gravity and magnetic components

ABSTRACTForward modelling of potential field data is an important part of optimization algorithms used to invert large datasets such as those involving rugged terrain or borehole data. Two‐dimensional fast Fourier transform modelling with a prism or a dipole is one of the most efficient methods compared to the forward modelling in the space domain. However, the exact solution of a prismatic source is limited to the case of a half‐space with the computation of data on a horizontal datum above the topography. Starting from the three‐dimensional Fourier forward modelling analytical formulation for a prism, an integration according to the wavenumber w is accomplished which allowed to find a two‐dimensional Fourier exact analytical formulation outside, at the interfaces of, and inside a prism for all potential field components. This new formulation requires the calculation of only four integrals. The gravity and magnetic fields are computed with this two‐dimensional fast Fourier transform formulation in the entire domain and compared with the analytical space domain and the three‐dimensional fast Fourier transform formulations. From the three‐dimensional calculated field, each component can be interpolated with the tri‐linear interpolation method along a borehole or on a drape surface simulating an airborne survey. Based on experiments demonstrated in this work, the two‐dimensional formulation in the Fourier domain gave accurate results with greater speed of execution in comparison to modelling in the space domain. The forward modelling method is tested on real gravity data from the north of Alberta (Canada).

MODELING OF THE LITHOSPHERE IN THE WHITE SEA REGION USING DECOMPOSITION OF ANOMALOUS GRAVITATIONAL AND MAGNETIC FIELDS

The research area includes the White Sea and adjacent land located in the junction zone of the eastern part of the Fennoscandian Shield and the Russian Plate. The purpose of the study is to construct a model of the lithospheric structure of the region using decomposition of anomalous gravitational and magnetic fields and inverse problem solving for components of gravity and magnetic fields, respectively. The decompositions of the fields were provided by the singular spectral method in the software package "R 4.3.1". The inverse problems were solved using the programs of the "Integro" complex. The components of the fields help to identify and analyze buried geological structures. The rift system of the White Sea is most clearly represented by the fourth component of the gravitational and magnetic fields. The positions of density and magnetic inhomogeneities of the Earth’s crust corresponding the components of the fields have been determined. The component model is compared with the seismic density and magnetic models of the lithosphere along the 3-AР geotraverse (Kem – White Sea Throat).

Evolution of an elastic blister in the presence of sloping topography

The propagation of a finite blister of fluid beneath an elastic sheet is controlled by the local dynamics at the peeling periphery of the current. Previous works have described constant volume elastic blisters by considering the peeling due to curvature at these edges. Here, we show that an along-slope component of gravity fundamentally changes the dynamics by removing the role of curvature at the trailing, upslope edge. The local dynamics of this trailing edge is instead controlled by shear stress in the sheet, as in the elastic Landau–Levich problem, and thereby allows for a receding edge, in contrast to propagation by peeling for which only an advancing contact line is possible. Using an asymptotic analysis, we show that this receding edge condition allows for a new, nearly translating regime in which the body of the blister moves at an approximately constant speed, leaving behind a thin layer of fluid. This prediction is verified by detailed numerical modelling of the two-dimensional downslope spreading. We conclude by discussing the applicability of these results in the rapid spreading of subglacial meltwater.

Widening the bandwidth of vibration energy harvester by automatically tracking the resonant frequency with magnetic sliders

The mismatch between excitation and resonant frequencies, and the narrow bandwidth of the traditional vibration energy harvester, result in small amounts of generating power. This paper presents a novel automated resonant frequency tracking method by using a pair of cylindrical movable magnetic sliders. To increase the bandwidth, the slider can track the resonant frequency on the cantilever beam without manual intervention or additional energy input. The proposed method is validated experimentally by the sliding behavior of the sliders on a cantilever beam within magnetic slider vibration energy harvester (CBMS-VEH). The CBMS-VEH demonstrates 2.7 times increasing in bandwidth for low acceleration (<0.5 g) and low frequency (<10 Hz). Under different excitation frequencies, the relationship between the friction force on the slider and the tangential component of the slider gravity can be tuned to move the slider to specified positions for further widening the bandwidth. The comparative experiments with conventional cantilever beam-mass vibration energy harvester (CBM-VEH) indicate that the resonant frequency tracking method of CBMS-VEH works in the wider range of the energy-harvesting bandwidth (6–9 Hz). Finally, we have successfully demonstrated the great potential of this method in powering low-power electronics, such as digital clocks and LEDs.

Experimental study on the droplet dynamics after impacting an inclined superhydrophobic surface

Super-hydrophobic surface has been widely studied, related to surface self-cleaning and liquid transport. In this study, effects of the inclined angle and impact velocity on the dynamic characteristics of droplet impact are experimentally investigated, using high-speed photography. When the spreading break-up does not occur, the effect of the inclined angle on the maximum spreading diameter is mainly determined by the competition between the decrease in the inertial force component normal to the surface and the increase in the gravity and inertial force component parallel to the surface. A formula has been developed to predict the maximum spreading factor under different inclined angles. The increasing inclined angle promotes the complete rebound. When the impact velocity is constant, there exists a critical inclined angle, at which the rebounding time is minimum. Furthermore, the critical inclined angle increases with the impact velocity. The increasing inclined angle can affect droplet ejection and potentially hinder its occurrence. Droplet ejection is classified into five stages based on the change in the ratio of the ejected to initial droplet diameter versus Weber number normal to the surface. For stage 5, an empirical formula that predicts the diameter of ejected droplets under different inclined angles is given out. This study can provide a novel idea for the generation and transport of microdroplets of directed size, as well as the recycling of the remaining liquid film after droplet ejection.

Formation optimization of downward overlaid Inconel 625 on curved surface of X65 pipeline basing on dynamic behavior of molten pool

In practical engineering, overlaying on curved surfaces with constantly changing gravity components usually leads to various defects. In this study, Inconel 625 was downward overlaid on curved surface by cold metal transfer (CMT) process with varied heat input, and the dynamic behavior of the molten pool was observed by high speed camera. At high heat input (0.422 kJ/mm and 0.372 kJ/mm), the volume of the molten pool continued to expand due to the downward flow of the liquid, ultimately leading to overflow or instability defects. In contrast, low heat input (0.230 kJ/mm) will make the molten pool shrink during overlaying, which was attributed to the continuously weakened gravity, the relative position between the heat source and the molten pool was then changed. A well-formed and defect-free weld overlay was obtained at optimized heat input 0.230–0.280 kJ/mm. Compared with gas tungsten arc welding (GTAW) process, the weld overlay obtained employing CMT process has the largest thickness and the most uniform fusion line, while the content of Fe element was less than 0.5%. It was confirmed that CMT technology has great potential for overlaying on curved surface.