Explore the vast range of titles available.

The parameter model of the full-open safety valve with different recoil disc convex angles is constructed. Additionally, the CFD software simulation and UDF dynamic mesh technology are used to analyze the change of the convex angle of the recoil disc of the spring full-open safety valve, the pressure distribution, and flow rate distribution of the front and rear areas of the valve disc and the recoil disc on the valve lift. The research results show that the valve lift curve of the recoil disc, convex at different side angles, exhibits clear proportional and protruding characteristics. The lift curve of the safety valve disc increases nonlinearly with the increase of the opening height, and the total lift appears at the maximum at the recoil disc convex angle of 72°. The main factor affecting the lift of the valve disc is the pressure in the front area of the recoil disc.

Recoil leaders develop in lightning flash decayed channels. The propagation of a recoil leader depends on the charges stored at its tip and the conductivity of the decayed channel. When the recoil leader propagates over the entire channel, a subsequent return stroke happens. Recoil leaders very often cease propagating before they reach the ground, that is, only part of the decayed channel is reionized. The present work aims to analyze the herein named secondary recoil leader that connect with the primary recoil leaders and cause them to start propagating again. We believe that the secondary recoil leader injects additional charge into the primary recoil leader, allowing the recoil leader reionize the whole decayed channel of the lightning flash. High‐speed videos analysis of upward lightning flashes shows that secondary recoil leaders play an important role on the formation and progression of dart leaders/subsequent return strokes. Plain Language Summary The recoil leader is a phenomenon that occurs in all types of lightning flashes (upward, downward and intracloud flashes). They arise in the remnants of decayed channels of positive leaders, partially or completely rebuilding these channels. The recoil leaders are responsible for some physical processes observed in lightning flashes. Thus, understanding how these physical processes originate is of significant importance. This work presents the role of secondary recoil leaders (recoil leaders that connect to preexisting recoil leaders) in the integral reconstruction of the decayed channels of the analyzed lightning flashes. Key Points Use of high‐speed cameras to study recoil leaders in upward lightning flashes Secondary recoil leaders boost the development of previous recoil leaders Secondary recoil leaders likely influence the development of dart leaders/subsequent return strokes

Recoilless launch can improve the adaptability of unmanned platforms to weapons by eliminating recoil, but it has the disadvantage of reducing the initial velocity of the projectile. The initial velocity of the recoilless gun can be improved by increasing the charge mass, so research into the recoilless efficiency of recoilless firing with increasing charge mass is of great importance for future applications of recoilless weapons. Based on the combustible cartridge and induction ignition, the one-dimensional homogeneous flow internal ballistic of a recoilless gun with high initial velocity is established. The effect of the Laval nozzle diameter on the efficiency of the recoilless gun is then investigated. The results show that, compared to conventional guns, the recoil can be reduced to 1N-s without reducing the initial velocity of the projectile. A ballistic test on a slide-rail mount is carried out to verify the results of the analysis. The results should make an important contribution to the development of a recoilless rifle.

The PandaX-4T is a dark matter direct search experiment with a dual-phase xenon detector. It is located at Jinping underground laboratory in Sichuan, China. In 2.8-ton fiducial mass and energy region of interest (range from 1 to 10 keV), the total electron recoil and nuclear recoil backgrounds are estimated to be (4.9±0.5) × 10 −2 mDRU and (2.8±0.5) × 10 −4 mDRU. With an exposure of 5.6 ton-years, the expected sensitivity of PandaX-4T could reach a spin-independent dark matter-nucleon cross section of 6 × 10 −48 cm 2 at a dark matter mass of 40 GeV/c 2 . An overview of detector design, background control and current status will be presented in this paper.

Aiming at the requirement of a 30% reduction in the recoil of the automatic shotgun, the researchers investigated the various thicknesses of the stock rubber, the different hardness of the stock rubber, and the floating buffer mechanism of the gun body. Researchers also conducted the recoil test and comparison to determine the structural scheme for recoil reduction. The test results indicate that the recoil force of the automatic shotgun is reduced by 51.9% compared with that of a fixed shotgun when using NBR (nitrile rubber buna) with a thickness of 20 mm and a hardness of 20 Shore hardness. The technical measures adopted are effective and can meet the requirements of the specified technical indicators.

In order to model recoil motion of artillery elaborately, the pneumatic recuperator was modelled and analyzed by thermodynamic theory, and a recuperator force model based on energy equation was proposed. The thermal power, mechanical power and gas equation of state were considered. Comparison with the classical recuperator force model based on polytropic process, the change of gas state with time is directly considered in this model. The effectiveness of the model was verified based on firing experiment data of a soft recoil artillery, and numerical analysis was carried out based on a normal recoil artillery. The results show that the recuperator force model based on energy equation can describe the hysteretic nonlinear properties of the gas state, and can predict the changes of gas pressure and temperature at the end of firing process relative to the start.

The fine-structure constant, α, is a dimensionless constant that characterizes the strength of the electromagnetic interaction between charged elementary particles. Related by four fundamental constants, a precise determination of α allows for a test of the Standard Model of particle physics. Parker et al. used matter-wave interferometry with a cloud of cesium atoms to make the most accurate measurement of α to date. Determining the value of α to an accuracy of better than 1 part per billion provides an independent method for testing the accuracy of quantum electrodynamics and the Standard Model. It may also enable searches of the so-called “dark sector” for explanations of dark matter. Science , this issue p. 191 Atom interferometry provides a precise measurement of the fine-structure constant. Measurements of the fine-structure constant α require methods from across subfields and are thus powerful tests of the consistency of theory and experiment in physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, we recorded the most accurate measurement of the fine-structure constant to date: α = 1/137.035999046(27) at 2.0 × 10 −10 accuracy. Using multiphoton interactions (Bragg diffraction and Bloch oscillations), we demonstrate the largest phase (12 million radians) of any Ramsey-Bordé interferometer and control systematic effects at a level of 0.12 part per billion. Comparison with Penning trap measurements of the electron gyromagnetic anomaly g e − 2 via the Standard Model of particle physics is now limited by the uncertainty in g e − 2; a 2.5σ tension rejects dark photons as the reason for the unexplained part of the muon’s magnetic moment at a 99% confidence level. Implications for dark-sector candidates and electron substructure may be a sign of physics beyond the Standard Model that warrants further investigation.

The purpose of this paper is to study the characteristics of recoil motion of a new suggested recoil system designed for the Russian 120- mm PM-38 mortar, rather than the conventional fixed-barrel mortar system. The new recoil system enables to reduce the total force imparted by the mortar system to the carriage, with the purpose of the mortar can be mounted on tracked/wheeled vehicles. The paper presents the suggestion of the new recoiling mortar system along with the discussion of the presentation of constructional considerations and constraints. The dynamic characteristics of recoil motion have been modelled with the aid of a new mathematical model that have been established using MATLAB software. As a result of the suggestion of the new recoiling mortar system, the maximum recoil resistance force is predicted to be reduced by more than 60% compared to that in the traditional fixed-barrel mortar system. In addition, the maximum recoil distance was predicted to be around 26 cm.

This paper presents modelling analysis and experimental testing of the performance of gun recoil system provided with variable recoil length and braked recuperator. The gun recoil cycle is studied considering the effect of presence of spring-loaded valve (SLV) in recoil system. A mathematical model has been developed using MATLAB/Simulink for the 130 mm M-46 Field Gun (FG). The model is validated by comparing theoretical recoil parameters with experimental data measured due to real firing tests. The firing tests were implemented for a new self-propelled system of the 130 mm FG that was designed and manufactured by the Egyptian Armed Forces. The results indicate that the recoil parameters are highly affected by the presence of the SLV. It has been found that the measured counter-recoil (CR) velocity is about 11% less than its counterpart predicted by the mathematical model without considering the effect of SLV. In addition, the driving force during CR is predicted to be 33% less compared to that without considering the effect of SLV. This causes the duration of CR time period to be 10% longer and the resistance against CR to be about 20% less compared to these values without considering the effect of SLV.

A bstract We introduce a — somewhat holographic — dictionary between gravitational observables for scattering processes (measured at the boundary) and adiabatic invariants for bound orbits (in the bulk), to all orders in the Post-Minkowskian (PM) expansion. Our map relies on remarkable connections between the relative momentum of the two­body problem, the classical limit of the scattering amplitude and the deflection angle in hyperbolic motion. These relationships allow us to compute observables for generic orbits (such as the periastron advance ∆Φ) through analytic continuation, via a radial action depending only on boundary data. A simplified (more geometrical) map can be obtained for circular orbits, enabling us to extract the orbital frequency as a function of the (conserved) binding energy, Ω( E ) , directly from scattering information. As an example, using the results in Bernet al. [ 36 , 37 ], we readily derive Ω( E ) and ∆Φ( J , E ) to two-loop orders. We also provide closed-form expressions for the orbital frequency and periastron advance at tree-level and one-loop order, respectively, which capture a series of exact terms in the Post-Newtonian expansion. We then perform a partial PM resummation, using a no-recoil approximation for the amplitude. This limit is behind the map between the scattering angle for a test-particle and the two-body dynamics to 2PM. We show that it also captures a subset of higher order terms beyond the test-particle limit. While a (rather lengthy) Hamiltonian may be derived as an intermediate step, our map applies directly between gauge invariant quantities. Our findings provide a starting point for an alternative approach to the binary problem. We conclude with future directions and some speculations on the classical double copy.