Equivalence Principle Research Articles

Observation of the effect of gravity on the motion of antimatter

Einstein’s general theory of relativity from 19151 remains the most successful description of gravitation. From the 1919 solar eclipse2 to the observation of gravitational waves3, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating content of the universe. Singularities in the general theory of relativity and the lack of a quantum theory of gravity suggest that our picture is incomplete. It is thus prudent to explore gravity in exotic physical systems. Antimatter was unknown to Einstein in 1915. Dirac’s theory4 appeared in 1928; the positron was observed5 in 1932. There has since been much speculation about gravity and antimatter. The theoretical consensus is that any laboratory mass must be attracted6 by the Earth, although some authors have considered the cosmological consequences if antimatter should be repelled by matter7–10. In the general theory of relativity, the weak equivalence principle (WEP) requires that all masses react identically to gravity, independent of their internal structure. Here we show that antihydrogen atoms, released from magnetic confinement in the ALPHA-g apparatus, behave in a way consistent with gravitational attraction to the Earth. Repulsive ‘antigravity’ is ruled out in this case. This experiment paves the way for precision studies of the magnitude of the gravitational acceleration between anti-atoms and the Earth to test the WEP.

Anisotropic viscoelasticity/damage coupled thermodynamic model for transparent polymer

Transparent polymer such as PMMA has been used for manufacturing viewport windows of deep-sea manned submersible. This paper develops an anisotropic viscoelasticity/ damage coupled thermodynamic model under finite-deformation framework for creep analysis of PMMA polymer. By introducing the strain equivalence principle with the effective stress concept, a four-order damage tensor that is composed of a two-order damage tensor conjugated to the two-order thermodynamic force, is imposed on the elastic tensors of two springs to describe mechanical degradation of material, and a damage potential function is proposed to derive the rate of two-order damage tensor. After the Drucker-Prager’s type failure criterion is met, damage induces anisotropy, which also accelerates damage evolution conversely. The developed model and numerical algorithm are first used to study the creep behaviors of a dog-done PMMA tensile specimen by comparing with the creep experimental results of material, and then the creep behaviors of the PMMA conical viewport window under constant water pressure by comparing with the creep experimental results of window well.

Current Status and Prospects on High-Precision Quantum Tests of the Weak Equivalence Principle with Cold Atom Interferometry

Current Status and Prospects on High-Precision Quantum Tests of the Weak Equivalence Principle with Cold Atom Interferometry

A nonlinear fatigue damage accumulation model under variable amplitude loading considering the loading sequence effect

Damage accumulation is nonlinear in the actual fatigue process, and the loading sequence is an important factor under variable amplitude loading. In this paper, a nonlinear fatigue damage accumulation model under variable amplitude loading considering the loading sequence effect is proposed. First, the cumulative rule of fatigue damage under variable amplitude loading is analyzed. It is suggested that the exponential function based on the load cycle ratio can be used to characterize the load sequence effect. Then, a nonlinear fatigue damage evolution equation of materials under constant amplitude load is proposed by taking the static toughness of the material as the damage parameter. Furthermore, the exponent of the load sequence influence parameter is determined as a function of the cycle life and elastic modulus. Then, a fatigue damage accumulation model under variable amplitude loading that considers the effect of the loading sequence is obtained based on the damage equivalence principle. Finally, the model is validated and compared through fatigue test data of five metal materials. It is found that the prediction accuracy of the proposed model is significantly higher than the other two models. In contrast, the difficulty of using the proposed model is lower than that of similar models.

An Assay on The Hobbesian Trap and Axioms of First Contact

Discussion surrounding first contact with extra-terrestrial intelligence (ETI) is hotly debated in the literature. This paper responds to claims made by Jebari and Olsson-Yaouzis that the ‘dominant thought’ in the philosophy of language indicates that communication with ETI would not be possible, and that the resultant uncertainty forces us into the Hobbesian Trap—the proclivity to adopt pre-emptive military strategies as a function of mutual distrust and fear of imminent attack. The ‘dominant thought’ in the philosophy of language constitutes largely behaviourist thinking and hinges on ‘shared human context.’ However, shared universal contexts, together with the potential existence of post-biological ETI, suggest that communication at a level sufficient to interpret basic dispositions (what I call the level of ‘performative function’) may be possible.Deploying both philosophical and game theoretical analyses, this paper provides several refutations and a repudiation of Jebari and Olsson-Yaouzis's claims: I correct the assumption that ETI would necessarily adopt a game theoretical rationality, critique the notion that ETI would choose a risk-dominant strategy rather than a payoff-dominant strategy, repudiate the claim that communication with ETI would not be possible, and show how the Hobbesian equivalence principle is violated in a proximal first-contact situation. Finally, in the absence of game theoretic decision-making (and inline with the calls from the Billingham report), this paper commences work on the development of an incomplete set of Axioms of First Contact from which to generate a definitive groundwork for both post-detection protocol and rules of engagement. An open invitation to other contributors to criticise, augment, and advance this bottom-up approach to first contact is extended.

A quantitative assessment method for the correlation between rock mass basic quality and Protodyakonov coefficient

With the implementation of the “Belt and Road” initiative, tunnel projects were designed in accordance with Russian design specifications and constructed by Chinese companies in countries along the route. Design companies and construction companies use different rock classification methods, which will increase the safety risk and cost of the tunnels. Therefore, it is necessary to study the correlation between Chinese engineering rock mass classification and Russian rock mass classification. The goal was to establish the correlation between rock mass basic quality (BQ) and Protodyakonov coefficient (f) for rock mass classification. Firstly, based on the equivalence principle of uniaxial compressive strength (UCS), the relationship between BQ and f containing the velocity index of rock mass (Kv) was established by comparing the relationship between f and BQ in the empirical formula of UCS. Secondly, through the equivalent principle of volumetric joint count of rock mass (Jv), we compared the empirical formula between the intactness index of Kv and rock quality designation (RQD) and conducted linear regression analysis on a large amount of data. The relationship between Kv and RQD was established. Finally, the relationship between BQ and f is quantitatively expressed and a classification table corresponding to the Russian rock classification and the Chinese engineering rock classification is obtained. The method is applied to Kyrgyzstan mountain tunnels.

A time-domain fatigue damage assessment approach for the tripod structure of offshore wind turbines

Welded features in the tubular joints are one of the most severe sources of fatigue failure in supporting structure for offshore wind turbines (OWTs). Therefore, fatigue resistance becomes a vital design, inspection and maintenance criterion for tripod supporting structures. This paper proposes a time-domain fatigue damage assessment approach for tripod structures by establishing a detailed finite element model for the critical zones and simplified beam model for the remaining regions. The stress influence matrix (SIM) is formed once by utilizing multiple finite element analyses. Based on the equivalent static loads and linear superposition principle, the time-variant stress can be efficiently calculated. By comparing the fatigue damage caused by multiple loads to that caused by a single load in a particular direction, we conclude that the advantage of the proposed method over the conventional stress concentration factors method. Afterwards, we investigate the effects of environmental conditions on the cumulative fatigue damage of critical zones. The fatigue resistances of various structures by altering angles between the main barrel and up brace, and a novel structure inspired by topology optimization, are promptly verified. All results indicate that the present approach can determine the fatigue damage for the tripod structure with precision and efficiency.

Delays in transferring patients from prisons to secure psychiatric hospitals: An international systematic review.

Transfer to a psychiatric hospital of prisoners who need inpatient treatment for a mental disorder is an important part of prison healthcare in the UK. It is an essential factor in ensuring the principle of equivalence in the treatment of prisoners. In England and Wales, delays in transferring unwell prisoners to hospital were identified by the 2009 Bradley Report. There has been no subsequent systematic review of progress in so doing nor a corresponding appraisal of transfer arrangements in other parts of the world. To conduct a systematic review of international literature about transfers of mentally unwell individuals from prison to hospital for the treatment of mental disorder since 2009. Eight databases were searched for data-based publications using terms for prison and transfer to hospital from 1 January 2009 to 4 August 2022. Inclusion criteria limited transfer to arrangements for pre-trial and sentenced prisoners going to a health service hospital, excluding hospital orders made on the conclusion of criminal hearing. In England, four articles were identified, all showing that transfer times remain considerably longer than the national targets of 14days (range, 14days to >9months); one study from Scotland found shorter mean transfer times, but more patients had been transferred to psychiatric intensive care units than to secure forensic hospitals. There were only two studies that investigated prison to hospital transfers for mental disorder from outside the UK and only one reported time-to-transfer data. Findings from this literature review highlight failures to resolve transfer delays in England and provide little evidence about the problem elsewhere. Given the lack of data, it is unclear whether other countries do not have this problem or simply that there has been no research interest in it. A possible confounding factor here is that, in some countries, all treatment for prisoners' mental disorders occurs in prison. However, the principle that prisons are not hospitals seems important when people need inpatient care. Prospective, longitudinal cohort studies are urgently needed to map transfer times and outcomes.

오염된 토지, 특히 폐기물이 매립된 토지와 하자담보책임

In the contract of sale, warranty liability for defects has the character of incomplete performance in that the original obligation was not fulfilled and according to the general principle of compensation for damages, it is reasonable to regard the contents of damages as defect warranty liability as performance gains. For this reason, recently, the Supreme Court, through the Supreme Court's decision 2017da202050 Decided April 8, 2021(hereinafter referred as ‘the Judgement’), made a ruling in the case of the sale of land where wastes were buried, even if the seller was not at fault, the amount of waste disposal costs that exceeded the purchase price was clearly recognized as damages according to warranty liability for defects. This is meaningful in that it was revealed that the scope of compensation for damages under warranty liability for defects in the sale of specific goods could reach the performance benefit separately from the fault of the seller. However, it would have been a more faithfully reflected judgment if it had been judged together with the calculation of the scope of damages on whether the principle of equivalence still plays its role in calculating damages under warranty liability for defects. In particular, in view of the fact that warranty liability for defects is operated as a seller's no-fault liability in principle, it would be a fair and faithful interpretation to consider that it is possible to adjust the scope of compensation for damages under the principle of good faith in consideration of the buyer's responsibility for the occurrence of defects. Such an interpretation of warranty liability for defects will play a role in drawing attention to the seller's obligation to provide warranty against defects in the object of sale, especially in cases involving environmental issues such as waste landfill.

The irreversibility of relativistic time-dilation

The fluctuation relations, which characterize irreversible processes in nature, are among the most important results in non-equilibrium physics. In short, these relations say that it is exponentially unlikely for us to observe a time-reversed process and, thus, establish the thermodynamic arrow of time pointing from low to high entropy. On the other hand, fundamental physical theories are invariant under time-reversal symmetry. Although in Newtonian and quantum physics the emergence of irreversible processes, as well as fluctuation relations, is relatively well understood, many problems arise when relativity enters the game. In this work, by considering a specific class of spacetimes, we explore the question of how the time-dilation effect enters into the fluctuation relations. We conclude that a positive entropy production emerges as a consequence of both the special relativistic and the gravitational (enclosed in the equivalence principle) time-dilation effects.

Lubrication analysis of the piston ring for the two-stroke marine diesel engine based on modified radial tension

As the piston ring is inserted into the bore, it is forced against the liner by radial tension, thereby creating a seal. Radial tension not only affects the piston ring’s seal, but also significantly influences its tribological properties. To investigate the effect of non-uniform radial tension of piston ring on the lubrication properties, a contact finite element model of piston ring and cylinder liner tribo-pairs is constructed in this study. The contact pressure distribution between the tribo-pairs is determined based on this model. The obtained pressure is then regarded as the non-uniform radial tension of the ring, which is fitted to a formula. The formula is validated in two ways. Firstly, its generality is verified by simulating several different piston rings using the contact model and comparing their results with the formula. Second, a test rig was designed and set up to measure the piston ring’s circumferential tension. To verify the formula’s accuracy, an equivalent principle model of distributed pressure and concentrated force was proposed. This formula is used as an initial force to modify the piston ring mixed lubrication model. Based on this model, the lubrication performance of the piston ring with uniform radial tension and non-uniform radial tension into consideration is investigated. The findings demonstrate that the piston ring radial tension is of significance to its lubrication performance and can be modified to lessen local friction and wear issues, particularly those related to the piston ring gap, and thus improve the dependability of the piston ring.

Gravitational redshift explained as a Doppler Effect in uniformly accelerated frames

Einstein predicted a change in the energy of photons in the proximity of a gravitational field, the change being directly proportional with the distance from the gravitational source. In the early 60’s Pound and Rebka have set to verify Einstein’s prediction. The experiment was reprised with even higher precision by Pound and Snider. Later, Vessot reprised the experiment in space at a much improved precision. The standard explanation of gravitational redshift falls out straight from the Schwarzschild solution of the Einstein Field Equations (EFE). In the following, we will present an approach to the experiment relying on the Einstein Equivalence Principle and on the recently derived expressions of Doppler Effect for uniformly accelerated motion of the source and the receiver. We will conclude with a chapter on the numerical limits of applicability of the described method.

Calibration Method of a Wideband AC Resistance Voltage Divider Based on an Equivalent Model.

Aiming at the problem of large measurement error and phase shift in resistance voltage dividers under high-frequency conditions in the field of power measurement, such as power harmonics, an error correction method is proposed for an alternating current (AC) resistance voltage divider based on the equivalence principle. Firstly, the frequency error model of the AC resistance voltage divider precision is established, and the angle difference of the continuous spectrum ratio difference from 50 Hz to 100 kHz is corrected by determining the shielding structure and the resistance parameters and fine-tuning the shielding potential correction method to reduce the capacities error of the AC resistance voltage divider design precision. At the same time, the performance parameters such as the direction and magnitude of the shielding potential compensation capacitive error are investigated. Finally, the precision voltage divider (the maximum voltage applied is 480 V) calibration experiments verify that the important characteristic judgment factor of the voltage divider is independent of the frequency and the equivalent capacitance value, which effectively solves the phase correction problem of harmonic power measurement.

A novel theoretical model for obtaining Norton's law of creep materials using different small specimens

The test method for evaluating the creep properties of a material using small specimens mostly relies on an empirical correlation equation derived through uniaxial tests, and it is difficult to obtain a unified theoretical model for creep specimens with different configurations. We propose a novel and unified theoretical model that describes the creep displacement–time curves based on the energy density equivalent principle, which can be expressed as h = h*B(P/A*)vt. A simple expression of the model parameters related to sizes was established for cantilever beam, ring compression, and flat small punch specimens using finite element analysis (FEA). Forward and reverse verification using FEA and experimental validation of the model using small specimens of a zinc alloy (ZA27) at 27°C were conducted. The results revealed that the Norton's law parameters predicted using the new creep model are in good agreement with the results obtained using the uniaxial creep test. The new model does not require an empirical correlation between the displacement and uniaxial reference equivalent strain and has a uniform characterization for four types of specimens with different configurations and sizes.

Research on the effect of double sealing gaskets arrangement on the mechanical behavior of the segment longitudinal joints with large diameter shield tunnel

The sealing gasket of the traditional double waterproof system of the large diameter shield tunnel consists of two sealing gaskets which are arranged on the outside of the bolt hole(SGOH) or arranged on both sides of the bolt hole(SGBH). The different arrangement of the double sealing gaskets has significant effects on the mechanical behaviors of the longitudinal joints of the segment. In this paper, based on the energy equivalence principle, the actual distribution stress of the compression zone of the segment longitudinal joints was simplified equivalently as rectangular distribution stress. Then, a progressive mechanical model was established for the longitudinal joint, taking into account the effect of double sealing gaskets arrangements. Furthermore, the proposed mechanical model was validated through former experimental results and other analytical models. Finally, the effect of different arrangements of the double sealing gaskets on the mechanical behavior of the longitudinal joints of the segment was compared and analyzed. The results showed that the difference in the arrangement of the double sealing gaskets results in varying effects of the additional bending moment on the joint bending deformation under sagging and hogging moments, leading to the unequal bending stiffness of the joint. The difference in bending stiffness caused by the double sealing gasket arrangements is approximately 100∼150 MN·m/rad. To optimize the mechanical behaviors of the joints, the double sealing gaskets should be arranged on both sides of the bolt hole(SGBH), with the bolt located at the center of both the longitudinal joints and the core compressive zone of the longitudinal joints.

STRING EXPANDS TO FABRIC

Consider the following experiment: a person is put in a room-size box high above the moon (chosen because there is no air and hence no air friction) with a bunch of measuring devices. This box is then taken high above the lunar surface and then let go: the box is then freely falling. The question is now, can the observer determine whether he/she is falling or whether he/she is in empty space unaffected by external forces (of course the answer is supposed to come before the box hits the surface). The answer to that is a definite NO! The observer can do experiments by looking at how objects move when initially at rest and when given a kick, he/she will find that they appear to move as is there were no gravitational forces at all! Similarly any experiment in physics, biology, etc. done solely inside the box will be unable to determine whether the box is freely falling or in empty space. Why is that? Because of the equality of the gravitational and inertial masses. All objects are falling together and are assumed to be rather close to each other (the box is not immense) hence the paths they will follow will be essentially the same for each of them. So if the observer lets go of an apple, the apple and the observer follow essentially the same trajectory, and this implies that the observer will not see the apple move with respect to him. In fact, if we accept the principle of equivalence, .We could find extra dimension in this experiment . International Journal of Scientific Research in Engineering and Management (IJSREM) Volume: 07 Issue: 08 | August - 2023 SJIF Rating: 8.176 ISSN: 2582-3930 © 2023, IJSREM | www.ijsrem.com DOI: 10.55041/IJSREM25096 | Page 2 nothing can be done to determine the fact that the observer is falling towards the Moon, for this can be done only if we could find some object which behaved differently from all the rest, and this can happen only if its gravitational and inertial masses are different. The principle of equivalence then implies that the observer will believe that he/she is an inertial frame of reference...until disabused of the notion by the crash with the surface. The principle of equivalence is of interest neither because of its simplicity, nor because it leads to philosophically satisfying conclusions. Its importance is based on the enormous experimental evidence which confirms it; as with the Special Theory, the General Theory of Relativity is falsifiable.

Evaluation of the microscale structure and performance of asphalt mixtures under different design methods

Asphalt mixture design methods have an important influence on both the microscale structure formed and the corresponding properties. This research compared the performance of asphalt mixtures with the Balanced design method, Marshall design method, and Superpave design method. CT scans were performed on the mixture specimens under different design methods to analyze the mixtures' void distribution law and skeleton structure stability. Then, the water stability of asphalt mixtures with different skeleton structures was evaluated by the water immersion Marshall test and freeze–thaw splitting test, and the effects of temperature and loading frequency on the dynamic modulus of asphalt mixtures under different skeleton structures were assessed by uniaxial compression dynamic modulus test. Finally, based on the time–temperature equivalence principle and Sigmoid model, the master curves of the dynamic modulus of asphalt mixtures under different design methods were constructed. The results showed that the number of coarse aggregate contact points and the average coordination number of asphalt mixtures were relatively larger under the Balanced design method, and the residual strength ratio of asphalt mixture under the Marshall design method was 1.4% larger than that of the Balanced design method, and the residual strength ratio of specimens under Superpave design method was 6.1% larger than that of the Balanced design method. At the same time, based on the differences in the air void of the specimens under different design methods and the different skeleton structures, the dynamic modulus laws under the action of different frequencies were obtained, and the mechanism of the influence of the skeleton structure on the dynamic modulus of the mixture was revealed. This research has important implications for the durability improvement of asphalt mixtures.

Can a variation of fine structure constant influence the fate of gravitational collapse?

We show that it is possible to steer clear of a spacetime singularity during gravitational collapse by considering time-variation of a fundamental coupling, in this case, the fine structure constant alpha . We study a spherical distribution of cold dark matter coexisting with other fluid elements, collapsing under its own gravity. The dark matter is written as a scalar field interacting with electrically charged matter. This leads to a time variation of alpha and as a consequence, a breakdown of local charge conservation within the sphere. The exterior has no such field and therefore, Einstein’s GR and standard equivalence principles remain valid. We derive the lowest possible bound on the collapse of this sphere beyond which there is a bounce and dispersal of most of the accumulated matter. We discuss the critical behavior of the system around this point and show that the bound is connected to a length scale of the order of Planck, introduced in the theory for dimensional requirements.

General formalism of the quantum equivalence principle

A consistent theory of quantum gravity will require a fully quantum formulation of the classical equivalence principle. Such a formulation has been recently proposed in terms of the equality of the rest, inertial and gravitational mass operators, and for non-relativistic particles in a weak gravitational field. In this work, we propose a generalization to a fully relativistic formalism of the quantum equivalence principle, valid for all background space-times, as well as for massive bosons and fermions. The principle is trivially satisfied for massless particles. We show that if the equivalence principle is broken at the quantum level, it implies the modification of the standard Lorentz transformations in flat space-time and a corresponding modification of the metric in curved space-time by the different mass ratios. In other words, the observed geometry would effectively depend on the properties of the test particle. Testable predictions of potential violations of the quantum equivalence principle are proposed.

Anchorage performance of large-diameter FRP bolts and their application in large deformation roadway

In underground coal mines, fibre reinforced polymer (FRP) bolt is ideal for mined rib reinforcements as it can prevent gas explosions caused by shearer frictional spark. With increasing mining depth, small diameter FRP bolts used in shallow underground mining cannot fulfil the rib support requirements. Under the engineering background of deep underground shortwall mining in Wudong coal mine, this paper systematically studies Φ27 mm FRP bolt support for large deformation coal rib. Specimens with a fan-shaped cross-section were used to enable the tensile testing of the bolt rod, the measured average tensile strength of the studied FRP bolt was (486.1 ± 9.6) MPa with a maximum elongation of 5.7%±0.6%. The shear strength of the bolt was measured as approximately 258 MPa using a self-made double shear testing apparatus. Based on the equivalent radial stiffness principle, a laboratory short encapsulation pullout test (SEPT) method for rib bolting has been developed undertaken consideration of the mechanical properties of the coal seam. Results showed that the average peak anchorage forces of the Φ27 mm FRP bolt and Φ20 mm steel rebar bolt were 108.4 and 66.4 kN, respectively, which were agreed with the theoretical calculations and field measurements. Based on theoretical analysis of the loading states of the bolt under site conditions, bolting method of full-length resin grouting was adopted to offset the weaknesses of the FRP bolt. Numerical method was employed to compare the bolting effect using Φ27 mm FRP bolts and steel rebar bolts. Large diameter FRP bolting was determined as the optimum rib support scheme to increase the productivity of the coal mine and to enhance the ground control capability for +425 level mining roadways. This study provides the laboratory testing design and theoretical prediction of large diameter FRP bolts used for rib support in large deformation roadways.