[show abstract][hide abstract] ABSTRACT: While modern dynamic driving simulators equipped with six
degrees-of-freedom (6-DOF) hexapods and X-Y platforms have improved
realism, mechanical limitations prevent them from offering
a fully realistic driving experience. Solutions are often sought in
the ”washout” algorithm, with linear accelerations simulated by an
empirically chosen combination of translation and tilt-coordination,
based on the incapacity of otolith organs to distinguish between inclination
of the head and linear acceleration. In this study, we investigated
the most effective combination of tilt and translation to
provide a realistic perception of movement. We tested 3 different
braking intensities (deceleration), each with 5 inverse proportional
tilt/translation ratios. Subjects evaluated braking intensity using
an indirect method corresponding to a 2-Alternative-Forced-Choice
Paradigm. We find that perceived intensity of braking depends on
the tilt/translation ratio used: for small and average decelerations
(0:6 and 1:0m=s2), increased tilt yielded an increased overestimation
of braking, inverse proportionally with intensity; for high decelerations
(1:4m=s2), on half the conditions braking was overestimated
with more tilt than translation and underestimated with more
translation than tilt. We define a mathematical function describing
the relationship between tilt, translation and the desired level of deceleration,
intended as a supplement to motion cueing algorithms,
that should improve the realism of driving simulations.
[show abstract][hide abstract] ABSTRACT: Special relativity considered in [Albert Einstein, Zur Elektrodynamik der bewegte Körper, Ann. Phys. 17 (1905) 891–921], and gravitation, studied in a series of papers, notably in [Albert Einstein, Zum gegenwärtigen Stände des Gravitationsproblemen, Phys. Z. 14 (1913) 1249–1262], are further analyzed regarding the principle of relativity, gravitation, and the notion of mass. The energy relation derived by Einstein from the relativistic Maxwell equations is applied to potential energy W(x) of the gravitational field along the right line for which Einstein’s transformations are valid. This defines the intensity G(x)=dW/dx of the relativistic force of gravity along a right line of observation in the gravitational field. The force is proportional to the observed acceleration according to the formula εG(x)=μξττ=μxttβ3 where μ is the inert mass in the second Newton’s law of motion and ε is the charge (mass) in the relativistic electromagnetic (gravitational) field. In everyday life, we see that all bodies visually fall under gravity (i.e. in a common gravitational field) with the same observed acceleration ξττ as if having equal inert and gravitational masses: μ/ε=1, with respect to the synchronized time τ. However, if the principle of relativity extended by Einstein to the case of the uniformly accelerated rectilinear motion is valid, then this relation should also be true with respect to xtt, that is, (μ/ε)β3=1, in proper time t of a still observer and of the carrying system (falling body), thus, depending on velocity v at which the acceleration ξττ is measured. This means that the inert mass μ and the gravitational mass ε can be considered equal only at v=0, and otherwise are related by the equation ε=μβ3≥μ, where Einstein’s calibration factor β=[1−(v/V)2]−0.5≥1,|v|V, and β≅1 for small |v| compared with the speed of light V=300000km/s at which we see the falling bodies. If v>0, then the observed gravitational mass ε is greater than the inert mass μ. The increase of mass is concurrent with the increase of tensions that at high velocities v→V induce overheating in the particle accelerators and colliders. To comply with the nature of observation, the information transmittal signals are incorporated in the Lorentz invariant of the 4D geometry, leading to the local invariants of relativistic dynamics that include gravitation and the speed of signals used in observation of moving bodies. With the same communication signals, those invariants hold for the synchronized time and coordinates of moving systems irrespective of their relative velocities. A procedure is developed for measurement and computation of the accelerations produced by variable gravitational and/or electromagnetic fields through the measurements of velocities of a moving body, so that the motion of the body and the field of forces acting on it can be fully identified. The results open new avenues for research in the theory of relativity and its applications.
Computers & Mathematics with Applications. 01/2011; 61:1517-1535.
[show abstract][hide abstract] ABSTRACT: We discuss the BRST and anti-BRST symmetries for perturbative quantum gravity
in noncommutative spacetime. In this noncommutative perturbative quantum
gravity the sum of the classical Lagrangian density with a gauge fixing term
and a ghost term is shown to be invariant the noncommutative BRST and the
noncommutative anti-BRST transformations. We analyse the gauge fixing term and
the ghost term in both linear as well as non-linear gauges. We also discuss the
unitarity evolution of the theory and analyse the violation of unitarity of by
introduction of a bare mass term in the noncommutative BRST and the
noncommutative anti-BRST transformations.
Modern Physics Letters A 02/2013; 491(3). · 1.11 Impact Factor
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