Inertial Field Research Articles

Theoretical study on pressure oscillation dominant frequency of bubbles submerged jet under rolling condition

Steam direct contact condensation is a highly efficient heat and mass transfer phenomenon, usually accompanied by strong mass, momentum and energy exchanges at the water-steam interface, which can rapidly realize cooling and pressure relief, but also accompanied by pressure oscillations. When the relevant equipment is used in offshore nuclear power plants and naval non-energetic systems, the additional inertial force field caused by ocean motion may cause greater harm to the safe operation of the relevant devices. Therefore, a theoretical study is conducted to investigate the effect of rolling motion on dominant frequency of steam submerged jets pressure oscillation with low mass fluxes. Firstly, based on bubble dynamics theory, a theoretical model of bubble condensation oscillations under rolling motion with low mass flux is established. Then, the mechanism of the rolling conditions on the dominant frequency of pressure oscillation is analyzed from the aspect of theoretical derivation. Finally, on the basis of the potential flow function theory and small perturbation theory, the predicted correlation of pressure oscillation dominant frequency under the rolling motion with low mass flux is derived, and compared with the numerical simulation results, the prediction deviation is within ±10%.

Invariant Kalman Filter Design for Securing Robust Performance of Magnetic–Inertial Integrated Navigation System under Measurement Uncertainty

This study proposes an enhanced integration algorithm that combines the magnetic field-based positioning system (MPS—Magnetic Pose Estimation System) with an inertial system with the advantage of an invariant filter structure. Specifically, to mitigate the nonlinearity of the propagation model and perturbing effect from the estimated uncertainty, the formulation of the invariant Kalman filter was derived in detail. Then, experiments were conducted to validate the algorithm with an unmanned vehicle equipped with an IMU and MPS receiver. As a result, the navigation performance of the IEKF-based inertial and magnetic field integration system was presented and compared with the conventional Kalman filter results. Furthermore, the convergence and navigation performance were evaluated in the presence of state variable initialization errors. The findings indicate that the inertial and magnetic field coupled with the IEKF outperforms the typical KF approach, particularly when dealing with initial estimate uncertainties.

Design and simulation of an accelerometer based on NV center spin–strain coupling

The nitrogen-vacancy (NV) center quantum systems have emerged as versatile tools in the field of precision measurement because of their high sensitivity in spin state detection and miniaturization potential as solid-state platforms. In this paper, an acceleration sensing scheme based on NV spin–strain coupling is proposed, which can effectively eliminate the influence of the stray noise field introduced by traditional mechanical schemes. Through the finite element simulation, it is found that the measurement bandwidth of this ensemble NV spin system ranges from 3 kHz to hundreds of kHz with structure optimization. The required power is at the sub-μW level, corresponding to a noise-limited sensitivity of 6.7×10−5g/Hz . Compared with other types of accelerometers, this micro-sized diamond sensor proposed here has low power consumption, exquisite sensitivity, and integration potential. This research opens a fresh perspective to realize an accelerometer with appealing comprehensive performance applied in biomechanics and inertial measurement fields.

Cavitation bubble structures below a soft boundary in an ultrasonic field

We studied the layer structure of bubbles just below water/air and water/EPE (Expand aple poly ephylene) interfaces using high-speed photography. The layer structure was generated by floating spherical clusters, the source bubbles of which were identified to come from the attachment of bubble nuclei at the interface, the floating of bubbles in the bulk liquid, or bubbles generated on the surface of the ultrasonic transducer. The boundary shape affected the layer structure, which assumed a similar profile below the water/EPE interface. We developed a simplified model composed of a bubble column and bubble chain to describe interface impacts and the interaction of bubbles in a typical branching structure. We found that the resonant frequency of the bubbles is smaller than that of an isolated single bubble. Moreover, the primary acoustic field plays an important role in the generation of the structure. A higher acoustic frequency and pressure were found to shorten the distance between the structure and the interface. A hat-like layer structure of bubbles was more likely to exist in the low-frequency (28 and 40 kHz) intense inertial cavitation field, in which bubbles oscillate violently. By contrast, structures composed of discrete spherical clusters were more likely to form in the relatively weak cavitation field at 80 kHz, in which stable and inertial cavitation coexisted. The theoretical predictions were in good agreement with the experimental observations.

Experience of amplitude-frequency estimation of ground vibrations in the range of 0,05–0,5 Hz using the sensing element of the GNU-KV gravimeter

Background. The responsive element of the GNU-KV Russian gravimeter comprises a Golitsyn lowfrequency vertical seismograph, which outperforms modern industrial SM-3KV seismographs in terms of sensitivity to ground vibrations. A team of geophysicists at the Sergo Ordzhonikidze Russian State University for Geological Prospecting modified the construction of GNU-KV to adapt this device to work in the mode of a portable seismological station for recording natural seismic vibrations in the frequency range of 0.05–0.5 Hz. Given the equivalence of gravitational and inertial fields, the presented technology is capable of not only detecting low-frequency ground vibrations, but also estimating accelerations and amplitudes of ground displacement at these frequencies.Aim. To investigate the capabilities of the GNU-KV gravimeter for recording and estimating the amplitude of ground vibrations in mm and mGal.Materials and methods. The proposed method for determining the anomalous areas of increased ground vibration using a GNU-KV gravimeter was tested in two geographical sites: in the vicinity of the Educational and Laboratory Complex of Sergo Ordzhonikidze Russian State University for Geological Prospecting and in the area of the RUDN University near a subway tunnel.Results. When determining the amplitude of ground vibrations in mm and their acceleration in mGal, the conversion coefficient for the results of a digital signal obtained by GNU-KV and inertial accelerations in mGal was determined.Conclusion. The conducted studies confirm the capabilities of the GNU-KV gravimeter for the quantitative estimation of ground vibrations.

MAGINAV: Long-Term Accurate Navigation Algorithm Using Inertial and Magnetic Field Sensor Fusion

MAGINAV: Long-Term Accurate Navigation Algorithm Using Inertial and Magnetic Field Sensor Fusion

Self-Test and Self-Calibration of Digital Closed-Loop Accelerometers

For accelerometers targeted in inertial navigation field, the DC bias error is the most destructive system error, affecting the final precision of long-term dead reckoning. This paper proposes a novel self-test and self-calibration technique for canceling out the DC bias error of the digital closed-loop accelerometers. The self-test of system DC bias is realized by injecting a 1-Bit ΣΔ modulated digital excitation and measuring the second-order harmonic distortion. As illustrated, the second-order harmonic distortion is related to the servo position deviation of the MEMS sensing element, which is one of the main causes of system DC bias error. The automatic capacitance compensation is carried out based on the amplitude and phase information of the detected second-order harmonic distortion, which can dynamically calibrate out the DC bias error. Test results show that there exists a near-linearity relationship between the system DC bias error and the second-order harmonic distortion, which is consistent with the proposed theoretical deduction. Based on the proposed method, the system DC bias error is effectively reduced from 150 to 4 mg, and unaffected by external acceleration bias.

Earth Velocity and Rigid-Body Attitude Estimation on SO(3) Using Biased Measurements

This article addresses the problem of simultaneously estimating: 1) the attitude of a rigid body on the special orthogonal group of order 3 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathsf {SO}(3)$</tex-math></inline-formula> ); 2) the Earth’s spin vector expressed in body-fixed coordinates; and 3) a pair of time-varying sensor measurement biases. The available sensor readings include biased angular velocity measurements collected from a set of high-grade rate gyros sensitive to the rotation of the planet and biased vector observations of some known inertial reference field. The estimation solution consists of a Lagrangian-based pseudo Kalman filtering routine, which is partially constrained to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathsf {SO}(3)$</tex-math></inline-formula> vis-á-vis the attitude. Most noticeably, the geometric relationship between the Earth’s angular velocity and the inertial field is leveraged to relax common practical, as well as theoretical, demands closely linked to conventional attitude estimation solutions, namely, the need for explicit body-fixed measurements of two inertial vector fields. The proposed algorithm is validated through a set of realisticsimulations. Experimental results are also included to further demonstrate the performance of this strategy in a real-world application.

ANTI-SYMMETRY AND CAVITATION TOPOLOGICAL DISRUPTIONS OF COMPLEX SPACE AND INERT MASS ON THE BASIS OF EXCIMER SYSTEMS OF QUANTUM GENERATION OF EXCHANGE INERTIAL RADIATION. MONOMER EQUILIBRIUM AND MATTER FORMATION

The proposed mechanism of formation of inert mass, electric charge and gravitational mass through cavitational topological ruptures of complex space. Stabilization of gaps is carried out through the quantum generation of exchange inertial radiation. On the basis of the relations of non-relativistic quantum mechanics, such radiation was separated into two components: zeron radiation from the zero energy level of the quantum oscillator and heaton radiation from higher levels populated as a result of thermal excitations. Different signs of energy and temperature in two subspaces of the complex space form an antisymmetric excimer system of exchange inertial radiation generation, while the decomposition of these systems into monomers leads to the formation of stable and quasi-stable forms of matter. The parameters of such forms in elementary and cosmic systems are calculated. Quantitative relations in gravitational systems, obtained by the universal use of the constant fine structure and the extended analogue of the Planck constant, are consistent with actual data, in particular, regarding the jet expansion of the Metagalaxy, non-stationary processes in the interior and in the shells of celestial bodies, the mechanisms of thermoregulation of the Earth’s climate and the generation of the geomagnetic field. Turbulent energy cascades in tribocontact and collider systems, manifested in the emission spectra of excimer structures in these systems, are analyzed. The components of the inert mass of leptons, mesons, and hadrons were calculated, and the stabilization of the group velocity of heaton radiation quanta in the basis of giant nuclear resonances was found. The processes of tunnel breakdown of the energy barrier of excimers, which lead to the formation of energy vortices and jets in natural systems of different levels of organization, are analyzed. The negative consequences of mixing excimer structures of the inertial field with monomeric structures are shown on the example of well-known disasters in nuclear power and hydropower. It is shown that the widely reproduced Lorentz-invariant forms of the fields and the limitations of Einstein’s theories of relativity on the rate of propagation of interactions are adequate only in isolated monomeric systems where primitive conservation laws apply. The results obtained in the work are completely consistent with the fundamental theological concept of Creatio ex nihilo.

Diplomacia cultural: uma arena de embates na Ditadura Militar

An analysis of Brazilian cultural diplomacy in the beginning of the military dictatorship (1964-1985) sheds light on the tensions that emerged between diverging interlocutors and different procedural currents on how the Brazilian State should project its message in the international system. Despite its efforts, the dictatorship was never able to pacify these conflicts, nor did it transform cultural diplomacy into regime propaganda. The coexistence of continuity and contradiction in cultural diplomacy suggests that it is a disruptive, inertial and erratic field.

Frequency Spectrum Separation Method of Suppressing Backward-Light-Related Errors for Resonant Integrated Optical Gyroscope

With on-chip integration enabled, resonant integrated optical gyroscope (RIOG) is a promising choice of rotation rate sensor in the novel micro inertial navigation systems. However, various optical errors, especially the backward-light-related errors including backscattering error and back-reflection error caused by the manufacturing process and heterogeneous materials in the optical elements, limit the performance of RIOG. Here, we propose the frequency spectrum separation method to suppress the backward-light-related errors for improving the detection precision of RIOG. The method can separate the angular velocity signal from the backward-light-related errors in the frequency domain. And, we investigate the optimal strategy of modulation frequencies to obtain maximum spectrum gaps of clockwise and counter-clockwise light for suppressing the backward-light-related errors, and simultaneously maintain maximum demodulation gain and minimum nonlinearity of optical effect for improving detection sensitivity. With the frequency spectrum separation method, the long-term bias stability of RIOG achieves 0.3°/h based on Allan deviation, which is the best reported result to the best of our knowledge. The proposed method of backward-light-related errors suppression can significantly improve the detection precision of RIOG based on a photonic chip, which contributes to the application of RIOG in the novel micro inertial navigation field such as cluster unmanned aerial vehicles and micro-nano satellites.

Visualization of hydrodynamic and physico-chemical processes in rotating and vibrating containers

Variable inertial fields are an efficient way to control the behaviour of hydrodynamic systems. Forces of inertia can be used, for example, to stabilize or destabilize systems with an interface or density gradient, to mix multiphase or non-isothermal fluids. The implementation of this approach means that liquids fill the periodically moving containers. In this paper, the situations are considered when the containers perform either rotation or translational vibrations. Methods for measuring the density and velocity fields of convective flows in reacting hydrodynamic systems are described. Interferometry is used to visualize the density distribution. Particle image velocimetry (PIV) is used to study the structure and velocity of the flows. Optical instruments are installed stationary in the laboratory system. For video recording, a camera shutter is synchronized with the motion of a container, and thus the images are captured in a fixed phase of oscillations or rotation. Constructions of the containers make it possible to illuminate the working volume through transparent walls at different angles or in different planes. They also provide a compensation for the centrifugal pressure and allow interference cells to be used in overload conditions. The successful application of the methods in experimental studies of chemo-hydrodynamic processes is demonstrated.

On the linear and non-linear fluid response to the circular forcing in a rotating spherical shell

Fluid flow excited by a core oscillating in a rotating spherical cavity is experimentally investigated. Oscillations are set by an external inertial field so that in the reference frame of the cavity, the core moves along a circular trajectory around the rotation axis. Two situations are considered: when the core oscillations are co-directed or counter-directed with respect to the rotation of the cavity. The oscillating core is a source of non-axisymmetric inertial waves that form a system of cone-shaped shear layers in fluid bulk. Depending on the oscillation frequency, various inertial flow regimes arise, the spatial structure of which strongly depends on the sign of the oscillations. It is found that a strong non-linear response in the form of a steady zonal flow corresponds to each flow regime. The flow structure is a system of nested liquid geostrophic cylinders, one of which is associated with the critical latitude at the core boundary, where inertial waves are generated. The next one is associated with the wave reflection from the cavity boundary and is clearly manifested when they are focused on the wave attractor. The most intense zonal flow occurs when inertial waves are superposed and global vortex structures are resonantly excited.

IMU Data and GPS Position Information Direct Fusion Based on LSTM.

In recent years, the application of deep learning to the inertial navigation field has brought new vitality to inertial navigation technology. In this study, we propose a method using long short-term memory (LSTM) to estimate position information based on inertial measurement unit (IMU) data and Global Positioning System (GPS) position information. Simulations and experiments show the practicability of the proposed method in both static and dynamic cases. In static cases, vehicle stop data are simulated or recorded. In dynamic cases, uniform rectilinear motion data are simulated or recorded. The value range of LSTM hyperparameters is explored through both static and dynamic simulations. The simulations and experiments results are compared with the strapdown inertial navigation system (SINS)/GPS integrated navigation system based on kalman filter (KF). In a simulation, the LSTM method’s computed position error Standard Deviation (STD) was 52.38% of what the SINS computed. The biggest simulation radial error estimated by the LSTM method was 0.57 m. In experiments, the LSTM method computed a position error STD of 23.08% using only SINSs. The biggest experimental radial error the LSTM method estimated was 1.31 m. The position estimated by the LSTM fusion method has no cumulative divergence error compared to SINS (computed). All in all, the trained LSTM is a dependable fusion method for combining IMU data and GPS position information to estimate position.

Superfluidity of non-condensate bosons in Bose–Einstein condensed systems

We present a general theory for superfluidity of non-condensate bosons in Bose–Einstein condensed systems. Considering a system enclosed in a cylindrical vessel rotating about its axis, the superfluid density is determined by analyzing the response of the system to an inertial force field specified by a vector potential in the frame rotating together with the vessel. We derive a general formula for the superfluid density of non-condensate bosons expressed in terms of Green’s functions. It is shown that the superfluidity of non-condensate bosons is caused by the anomalous self-energy describing the pairing correlation between them. The total superfluid density is given by the sum of the condensate density and the superfluid density of non-condensate bosons, reducing to the Landau formula within mean-field approximations neglecting the damping of quasiparticles. We generalize the linear relation between the current and inertial vector potential to satisfy the gauge invariance, introducing the pairing wave function for the superfluid component of non-condensate bosons. We find that the phase of the pairing wave function is twice that of the condensate wave function and the circulation is still quantized in units of 2π∕m even in the presence of the pairing current of non-condensate bosons.

Centrifugal convection in a two-layer system of reacting miscible fluids

The authors study the effect of uniform rotation on the system of two reacting miscible liquids placed in a cylindrical Hele-Shaw cell. The cell performs a rotation with a constant velocity around the axis of symmetry resulting in a radially directed inertial field. The initial configuration of the system is statically stable and consists of two concentric layers of aqueous solutions of acid and base, which are spatially separated. When liquids are brought into contact, a neutralization reaction begins, which is accompanied by the release of salt. In this work, we obtain a system of governing equations and present the results of numerical simulation. We found that reaction-diffusion processes lead to the formation of a non-monotonic density profile with a potential well. If the rotation rate gradually increases, then a cellular convection pattern can develop in the potential well. We found that with further growth of the control parameter, the periodicity of the pattern is violated due to the influence of another convective instability, which independently develops in the domain close to the axis of rotation. The action of the inertial field results in the ejection of some convective vortices from the potential well.

Effect of vibrations on thermal convection in thick rotating annulus

The effect of transverse vibrations on thermal convection in a rotating thick cylindrical fluid layer is investigated experimentally. The layer rotates about the horizontal axis of symmetry. The temperatures of the layer boundaries are different (the outer boundary is cold) and maintained constant. The study is limited to the case of fast rotation. The centrifugal force of inertia plays a stabilizing role, bringing the fluid into a state of a stable mechanical equilibrium. The vibrations affect the equilibrium of the layer in a narrow frequency range close to the rotation frequency. The structure of the convective flows is studied using PIV-method. It is found that when the frequencies of vibrations and rotation definitely coincide, the convective flow has a form of the couple of symmetric two-dimensional vortices, the position of which is stationary in the cavity reference frame. The convection occurs under the action of an induced inertial force field (superposition of vibrational and centrifugal inertial force fields). With a frequency mismatch, the induced force field rotates in the cavity reference frame. The maximum heat transport corresponds to a resonant excitation of the azimuthal two-dimensional inertial oscillations of the non-isothermal fluid layer. The convective heat transport in this case is much higher than in the case of the frequencies coincidence. The dependence of heat transport, both under resonance conditions and with equal frequencies, on vibration parameters is studied. It is shown that the centrifugal and vibrational mechanisms play a key role in the development of the convection.

Physics Formalism Helmholtz Iyer Markoulakis Hamiltonian Mechanics Metrics towards Electromagnetic Gravitational Hilbert Coulomb Gauge String metrics

Iyer Markoulakis Helmholtz Hamiltonian metrics have been gauged to Coulombic Hilbert metrics, representing Gilbertian and Amperian natures of electromagnetic fields from mechanics of vortex rotational fields acting with gradient fields, typically in zero-point microblackhole general fields, extending to vacuum gravitational fields gauge. This ansatz general gaging helps to properly isolate field effects with physical analyses – mechanical, electric, magnetic components within the analytical processes. Vacuum gravitational fields and the flavor Higgs-Boson matter inertial gravitational fields have been thus quantified extending to stringmetrics constructs matrix showing charge asymmetry gauge metrics. Physical Analysis with applications to particle physics, Quantum ASTROPHYSICS, as well as grand unification physics have been advanced. Particle physics gauge matrix pointing to Dirac seas of electrons, monopoles with positrons, electron-positron annihilation leading to energy production, and the relativistic energy generating matter provided literature correlations. Quantum astrophysics extending gauge metrix analyzes of superluminal profile of signals velocity generating electron-positron chain like “curdling” action validates formalism with physics literature of electron-photon observed oscillatory fields configurations. Mechanism of creation of neutrino antineutrino pair orthogonal to electron positron “curdling” planes, that may lead to formation of protonic hydrogen of stars or orthogonally muon particles. These proposals will help to explain receding or fast expanding universe with the dark matter in terms of flavor metrics versus gauge associating metrics fields. Vacuum and gravitational monopoles, that are representation of compressed mass out of vortex Helmholtz decomposition fields have been interpolated to energy generation via electron positron monopole particles at cosmos extent of infinity

Transient contact-impact behavior for passive walking of compliant bipedal robots

When bipedal robots walk, the compliance of local contact zone and whole structure usually causes high amplitude contact force and wave propagation excited by impact. The object of this paper is to analyze the transient contact-impact behavior during the walking of compliant bipedal robots (CBR) using a completely flexible body model (CFBM) and obtain its fine contact modes. The applicability of the traditional method based on completely rigid body model (CRBM) to the compliant bipedal robots is also discussed. In CFBM, the structural deformation field and inertial field are discretized by finite element theory, and the penalty function method is adopted to account for the unilateral contact constraint. The dynamic equations, strain and stress equations for the CFBM are derived. The contact forces, impact-induced wave propagation and total mechanical energy of the CBR are calculated. The results show that the relative contact motions between the foot and the slope experience two phases: (1) macroscopic oblique impact phase (duration time is 0.1∼0.2 s) and (2) rolling phase (duration time is 0.6∼0.7 s). Phase 1 consists of a series of fast normal contact-separation switches and tangential stick–slip switches. Phase 2 means there are continuous normal compression and tangential stick. Since the traditional method neglects the first phase, it is not comprehensive for investigating the CBR with impact-induced waves and vibration, especially for the case of lower coefficient of friction (COF) μ. In addition, a ‘dynamic self-locking’ phenomenon is found as μ>0.9, which will lead to the walking unstable.

Inertial waves generated by circular oscillations of inner core in a rotating spherical cavity

The fluid flow excited by a core oscillating in a rotating spherical cavity is experimentally investigated. The core performs circular oscillations around the rotation axis under the action of an external inertial field and generates inertial waves. The main attention is paid to the effect of the oscillation frequency on the instantaneous flow structure and intensity. It is found that at a certain frequency, inertial waves experience spatial resonance, resulting in the intensification of oscillatory flow.