Control of vibrational field in an elastic vibration unit with DC motors and time-varying observer

In the paper the problem of feedback control of vibrational fields in a vibration unit is analyzed taking into account the influence of the elasticity of cardan shafts, the drive dynamics, saturation for control torques. In addition, the synthesized rotor synchronization control algorithm uses the estimates of a non-stationary observer, which makes it possible to implement it practically on a two-rotor vibration unit SV-2. The performance of the closed loop mechatronic systems is examined by simulation for the model of the two-rotor vibration unit SV-2.

Optical data implies a null simultaneity test theory parameter in rotating frames

The simultaneity framework describes the relativistic interaction of time with space. The two major proposed simultaneity frameworks are differential simultaneity, in which time is offset with distance in “moving” or rotating frames for each “stationary” observer, and absolute simultaneity, in which time is not offset with distance. We use the Mansouri and Sexl test theory to analyze the simultaneity framework in rotating frames in the absence of spacetime curvature. The Mansouri and Sexl test theory has four parameters. Three parameters describe relativistic effects. The fourth parameter, [Formula: see text], was described as a convention on clock synchronization. We show that [Formula: see text] is not a convention, but is instead a descriptor of the simultaneity framework whose value can be determined from the extent of anisotropy in the unidirectional one-way speed of light. In rotating frames, one-way light speed anisotropy is described by the Sagnac effect equation. We show that four published Sagnac equations form a relativistic series based on relativistic kinematics and simultaneity framework. Only the conventional Sagnac effect equation, and its associated isotropic two-way speed of light, is found to match high-resolution optical data. Using the conventional Sagnac effect equation, we show that [Formula: see text] has a null value in rotating frames, which implies absolute simultaneity. Introducing the empirical Mansouri and Sexl parameter values into the test theory equations generates the rotational form of the absolute Lorentz transformation, implying that this transformation accurately describes rotational relativistic effects.

On the ‘Rigidity’ of the Force Field of a Moving Source

In the present paper, we propose a heuristic and intuitive approach to visualize how force fields “move” when their source moves at a constant velocity [Formula: see text] or accelerates with acceleration [Formula: see text] relative to a stationary observer. Our approach is based on the application of the principle of relativity and the principle of equivalence and holds regardless of the nature of the force field. The results presented here have been derived in the nonrelativistic approximation ([Formula: see text] and [Formula: see text], [Formula: see text] being the interval of time within which we observe the field). We shall show that in both cases of uniform and accelerated motion of the source, the field moves rigidly with the source. Namely, for every observer, however distant from the source, the field is always directed away from (or points towards) the present, instantaneous position of the source. We also show that these results are in agreement with what we know from experimental evidence and full-fledged physical theories (of electromagnetism and gravitation) beyond the nonrelativistic approximation. The proposed approach may be considered as a tool to facilitate students in graduate and undergraduate courses to familiarize themselves with (and self convince of) such a counter-intuitive feature of the force fields.

An approach to directly probe simultaneity

The theory of special relativity derives from the Lorentz transformation. The Lorentz transformation implies differential simultaneity and light speed isotropy. Experiments to probe differential simultaneity should be able to distinguish the Lorentz transformation from a kinematically-similar alternate transformation that predicts absolute simultaneity, the absolute Lorentz transformation. Here, we describe how published optical tests of light speed isotropy/anisotropy cannot distinguish between the two transformations. We show that the shared equations of the two transformations, from the perspective of the “stationary” observer, are sufficient to predict null results in optical resonator experiments and in tests of frequency changes in one-way light paths. In an influential 1910 exposition on differential simultaneity, Comstock described how a “stationary” observer would observe different clock readings for spatially-separated “moving” clocks. The difference in clock readings is an integral aspect of differential simultaneity. We derive the equation for the difference in clock readings and show that it is equivalent to the Sagnac correction that describes light speed anisotropies in satellite communications. We describe an experimental strategy that can measure the differences in spatially-separated clock times to allow a direct probe of the nature of simultaneity.

Film space as mental space

This paper explores the hypothesis that the three-dimensionality and continuity of film space is a mental construct based on our perception of the images projected on the screen and our knowledge of/about the world and our knowledge of/about film. Starting from Alberti’s (1804 [1435]) visual pyramid as a geometric representation of the vision of a stationary observer, such as a painter, and Gardies’ (1993) mirror ball representing the vision of a dynamic spectator, such as a camera, the paper proposes a new schema aiming to explain how the three spaces – real, virtual, and mental – participate in the construction of film meaning.

ON THE ENERGY–MOMENTUM FLUX IN GÖDEL-TYPE MODELS

In this paper, we work in the context of Teleparallelism Equivalent to General Relativity (TEGR) in order to construct the energy–momentum flux for Gödel-type solutions of Einstein's equations. We use an stationary observer, which is settled by the tetrad choice, to obtain the gravitational pressure for each direction of space in cartesian coordinates. Then, we write down the total pressure for each direction in terms of the pressure of the fluid, thus we are able to identify the role of the gravitational pressure.

Research on Total Error of Anti-Radiation Missile against Target Radiation Source Shutdown

This paper established the total error model of Anti-Radiation Missile under condition of target radiation source shutdown, which includes three dimensional passive location error model using information of azimuth and elevation angle as well as their changing rates, and gyroscope drift error model of Strap-down Inertial Navigation System. By analyzing the three dimensional passive location method to moving emitter using single stationary observer, the paper had a research to the hit probability of Anti-Radiation Missile under various flying conditions. If higher hit probability is required, the missile should increase its azimuth and elevation angle as much as possible while not to overstep its attack angle. Simulation result showed that the shutdown occasion of radiation source did much influence to the hit probability of Anti-Radiation Missile, which has great meaning to improve he bat efficiency of Anti-Radiation Missile.

Judgments about Collisions in Simulations of Scenes with Textured Surfaces and Self-Motion: Do Display Enhancements Affect Performance?

To move through the environment safely, people must make effective judgments about collisions. It has been asserted that most studies of time-to-collision judgments are limited due to a lack of visual realism (Manser & Hancock, 1996). Studies that compared performance among displays which differed in realism provided mixed results. We measured judgments about whether, and when, two objects would have collided with each other. Results from simulations of scenes with colored, textured surfaces and a moving observer were mostly comparable to earlier results from simulations of black-and-white, line-drawn objects and a stationary observer (DeLucia, 1995; DeLucia & Meyer, 1999). Texture and self-motion affected performance in a restricted set of conditions and did not eliminate errors due to misleading depth cues. Increases in realism, which incur more costs and computational time, may not always be justifiable from a performance standpoint. Results have design implications for simulators and virtual reality systems.