Investigating the Conditions of Automatic Assembly of Polyhedral Joints

Purpose – Providing the technological reliability of the robotic assembly of joints with RK-profile on the basis of adaptation devices and low-frequency oscillations. Design/methodology/approach – Ensuring the assembly conditions is achieved by the vibration device that provides oscillations relative to the two axes, perpendicular to the assembly direction and rotation about the assembly axis. Compensation of the linear error in the position of the parts is attained by an adaptive gripper with a flexible link. Findings – A mathematical model describing the assembly process of parts relative to the non-inertial coordinate system is developed. The technological modes of profile parts assembly are defined. Originality/value – The robotic assembly method of profile joints by the adaptation devices, namely a combination of elastic fixing of the installed profile part and the simultaneous rotation and vibration of the base part to improve the process reliability is developed. Experimental studies confirmed the adequacy of the created mathematical model. The patent for the assembly method of profile joints with a gap is received.

On the subject of influence of dissipative and constant of moments on the stability of uniform rotations of non-free two elastically connected gyroscopes of Lagrange

The conditions for asymptotic stability of uniform rotations in a resisting medium of two heavy Lagrange gyroscopes connected by an elastic spherical hinge are obtained in the form of a system of three inequalities. The bottom gyroscope has a fixed point. The rotation of the gyroscopes is maintained by constant moments in the inertial coordinate system. The influence of the elasticity of the hinge on the stability conditions is estimated. It is shown that for a sufficiently high rigidity of the hinge, the asymptotic stability conditions are determined by only one inequality, which coincides with the inequality obtained for the case of a cylindrical hinge. When the angular velocities of the gyroscopes' own rotations coincide, this inequality coincides with the well--known condition for one gyroscope. Cases of degeneration of an elastic spherical hinge into a spherical inelastic, cylindrical and universal elastic hinge (Hooke's hinge) are considered. For the Hooke hinge, it is shown that there is no asymptotic stability at a sufficiently high angular velocity of gyroscopes rotation.

The Special theory of relativity in different media(Ⅰ)

In this paper, the special theory of relativity in different media is established, based on the fundamental invariant of the space-time four-dimensional space x2 + y2 + z2 - c2 t2 = x'2 + y'2 + z'2 - c' t'2 . First of all, the inertial coordinate system is strictly defined in mathematical language. The inertial coordinate system that uses the actual measured different speeds of light as the limit speed still retains its most basic characteristics as an inertial coordinate system. Then, the space-time coordinate transformation and velocity transformation formulas between inertial coordinate systems with different light velocity are derived. These results not only break through the limitation of "vacuum", but also all are exactly the same as the conclusions of the traditional special theory of relativity when c = c' ; and when c ≠ c' give the new physical content. This all lifted the threat of the theory of relativity by the speed of light experiment, making c = c' ; and c ≠ c' both inclusively under the basic point of view of the theory of relativity; which will inevitably broaden the way of using relativity to deal with physics problems and clarify many problems left over in the study of relativity. The article discusses the problem of relativistic kinematics involving the measurement of time and space, correctly interprets the effects of “ruler contraction” and “clock retardation”, and uncovers and correctly answers the “clock paradox” that accompanied the birth of relativity. For two motion systems S and S', that are separated from each other by constant velocity, at any time and where, the product of the proper time elapsed evenly and uniformly and the speed of light in the respective system are equal, cτ = c' τ'; and the product of the coordinates time read out in observing and recognizing the other party's proper time and the speed of light in the respective system are also equal, ct = c' t' . It is confirmed that the product of any moving individual's uniform disappearance proper time and its measured speed of light remain unchanged; and the proper time cannot be determined purely by the individual's subjective way. Deduced the uncertain relationship between the proper time and the coordinate time for an inertial coordinate system which was not noticed by the traditional special theory of relativity. Remind the practical astronomy workers who do the time measurement and the time service work to understand that it is impossible to equate practical scientific coordinate time and the proper time of ideal uniform disappearance (the so-called “Ephemeris Time”). Thereby pay attention to the impact of this uncertain relationship on the time measurement and the time service work, and propose ways to verify. Subsequent work will use this expanded special theory of relativity to conduct a comprehensive review of related physics, which will inevitably extend to issues that have not been or cannot be examined by traditional special theory of relativity.

A new result under weak and non-relativistic approximation from general theory of relativity

We have derived a metric field equation in the locally inertial coordinate system from Einstein's field equation considering the energy density of the moving particle with the approximations that the force field under which the particle is moving is weak and the velocity of the particle is non-relativistic. We study the motion of different microscopic systems using this metric equation and compared the results with the experimentally measured values and we find that the results are identical.

Velocity and absurdity in modern physics

When physicists write the variable v, they usually mean the velocity of an object in an inertial coordinate system, otherwise known as a reference frame. This is the most common velocity concept in modern physics. The velocity of an object in this sense depends on which inertial coordinate system one is working with. For example, an airplane in flight has a velocity of about 500 miles per hour in a coordinate system anchored in a nearby mountain, a velocity of more than 60 000 miles per hour in a coordinate system anchored in the sun, and a velocity of 0 in a coordinate system anchored in the airplane itself. The widely accepted idea that the ticking rate of a clock is a function of this type of clock velocity is absurd. It implies that a human analyst can control the ticking rates of physical clocks through the mental act of selecting a coordinate system. This is a nonsensical mingling of imagination with reality that is akin to believing that a movie character can jump out of your television set and take a seat in your living room. Despite this absurdity, the idea that a clock’s ticking rate depends on its velocity in an inertial coordinate system is a staple of modern physics. It is a pillar of Einstein’s special theory of relativity. It is central to the standard analysis of the so-called twin paradox. It underlies the predictions of Hafele and Keating concerning the ticking rates of clocks that travel in airplanes. Velocity absurdity of this sort flourishes today, and it may well continue to flourish for many years to come.

Integrated navigation approaches of vehicle aided by the strapdown celestial angles

The integrated navigation method based on star sensor celestial angles (altitude angle and azimuth angle) is proposed to serve the need for rapidly responsive, reliable, and precise of a hypersonic vehicle under a sophisticated environment. An integrated navigation algorithm suitable for large azimuth misalignment is established under launching point inertial coordinate and local geographical coordinate system based on altitude angle and azimuth angles. Meanwhile, a Bayesian method for data dropouts aided by the strapdown celestial angles is presented for the rapid variability in the celestial star angle with active galaxies. A nonlinear Bayesian filter is applied to implement the simulation on account of the nonlinear feature of the state and measurement equations. The simulation results showed that the Bayesian method for integrated navigation data dropouts could be accomplished by altitude angle and azimuth angle aiding in both launching point inertial coordinate and local geographical coordinate systems, which converge to 1′ in 10 s. The method indicated that the integrated navigation significant errors derived from initial localization and initial attitude alignment could be modified by the strapdown inertial navigation system (SINS) supported by the star sensor’s celestial angle in the local geographic coordinate system in the early launch stage. For the seconds of the flight phase, the integrated navigation aided by celestial angles in the launching point inertial coordinate system was guaranteed for the feasibility and validity. During the flight, the feasibility and validity of integrated navigation were guaranteed aided by celestial angles in launching point inertial coordinate system.

Magnitude and direction of the local interstellar magnetic field inferred from Voyager 1 and 2 interstellar data and global heliospheric model

In this Letter, we provide constraints on the direction and magnitude of the pristine (i.e., unperturbed by the interaction with the Sun) local interstellar magnetic field. The constraints are based on analysis of the interstellar magnetic field components at the heliopause measured by magnetometer instruments on board Voyager 1 and 2 spacecraft. The analysis was performed with the help of our kinetic-magnetohydrodynamical model of the global heliosphere. The model shows that the solar-induced disturbances of the interstellar magnetic field are extended relatively far from the Sun up to 400−500 AU. The field is draped around the heliopause and compressed. By comparison of the model results with Voyager data we found that the model provides results comparable with the data for the interstellar magnetic field of BLISM = 3.7−3.8 μG in magnitude and directed towards ≈125° in longitude, and ≈37° in latitude in the heliographic inertial coordinate system.

Counterexample and example of the principle of relativity

In the Earth-centered locally inertial coordinate system, the Principle of Relativity is not satisfied when using the experimental data of the global positioning system (GPS). The clocks in the GPS satellites tick off time more slowly by the velocity v G = 4 km/s after elimination of the gravitational effects. Between two local gravity fields, the Principle of Relativity is satisfied.

Influence of the Dynamic Motion of a Splash-Lubricated Gearbox on Churning Power Losses

To investigate the influence of the dynamic motion of a gearbox on lubricating flow field and churning power losses under splash lubrication, a computational fluid dynamics (CFD) method based on a combination of the fluid of volume (VOF) method and turbulence model is presented in this paper. A non-inertial coordinate system was employed to simulate the motion of the gearbox, and the feasibility and accuracy of the method was validated by the available experimental results. Numerical models of the gearbox with a spur gear pair under no load operation condition were established, and sinusoidal motions with different frequencies and amplitudes were implemented in the gearbox. The effects of the rotational speed of gears, oil immersion depth, and the frequency and amplitude of sinusoidal motions were studied. The results showed that the dynamic motion of the gearbox can exert a significant influence on churning losses and the oil supply of the gear contacting zone, and the gear pair may be in a loss-of-lubrication state.

Correction Strategy of Mortars with Trajectory Correction Fuze Based on Image Sensor

For a higher accuracy of projectiles, a novel trajectory correction fuze is proposed. In this design, the sensor and actuator were reduced to achieve a balance between performance and affordability. Following introduction of the fuze concept, the flight model was presented and the crossrange and downrange components of trajectory response under control were investigated. The relationship between the inertial coordinate system and the detector coordinate system was studied so that the imager feedback could be used to derive the actual miss distance. The deployment time of canards and roll angle of the forward fuze were derived and used as the inputs of the control system in this strategy. Example closed-loop simulations were implemented to verify the effectiveness of the strategy. The results illustrate that the accuracy increase is evident and the proposed correction concept is applicable for terminal correction of mortars.