Inertial Features Research Articles

Real-time smart and standalone vision/IMU navigation sensor

In this paper, we present a smart, standalone, multi-platform stereo vision/IMU-based navigation system, providing ego-motion estimation. The real-time visual odometry algorithm is run on a nano ITX single-board computer (SBC) of 1.9 GHz CPU and 16-core GPU. High-resolution stereo images of 1.2 megapixel provide high-quality data. Tracking of up to 750 features is made possible at 5 fps thanks to a minimal, but efficient, features detection–stereo matching–feature tracking scheme runs on the GPU. Furthermore, the feature tracking algorithm benefits from assistance of a 100 Hz IMU whose accelerometer and gyroscope data provide inertial features prediction enhancing execution speed and tracking efficiency. In a space mission context, we demonstrate robustness and accuracy of the real-time generated 6-degrees-of-freedom trajectories from our visual odometry algorithm. Performance evaluations are comparable to ground truth measurements from an external motion capture system.

Crime and punishment: evidence from dynamic panel data model for North Carolina (2003–2012)

This paper exploits a dynamic panel data model to analyze the endogeneity of certain deterrent covariates, measurement errors in crime and inertial features of crime, and to check for unobserved heterogeneity in order to extract more precise and reliable estimates of the deterrent effect of law enforcement in North Carolina. It uses panel data on 90 counties of North Carolina over the period 2003–2012. After checking various socioeconomic covariates, among the deterrent variables, likelihood of arrest and conviction always showed deterrent effects on criminal behavior for different kinds of violent and property crimes. Since property crimes have relatively higher inertia than violent crimes, their associated long-run elasticities with respect to significant deterrence variables are greater, which implies that allocating more resources to increasing the likelihood of arrest for property crimes can effectively decrease them in the long run.

An analysis of dynamics of risers during vessel motion by means of the rigid finite element method

The widespread use of lines, cables and risers in offshore applications requires research on the dynamic behavior of such systems. Accurate prediction of riser motion during operations is crucial. The models presented in the paper are used for static and dynamic analysis of planar slender systems undergoing large elastic deformations. Slender links are discretized by means of a modification of the rigid finite element method, which allows us to consider both bending and longitudinal flexibility. The method consists in dividing a link into rigid finite elements assuming inertial features connected by massless spring-damping elements; additionally, a spring element reflecting longitudinal flexibility is added. The formulation of the method presented allows us to take into account hydrodynamic forces and added mass. Correctness of the models and programs developed is proved by comparison of the results with an analytical solution and commercial software.When installing or moving a riser to a new site, any contact between it and another object should be prevented if possible. Thus, the numerical simulations presented in the paper concern the movement of a vessel with an attached riser (with and without fluid) in such a way that an obstacle on the seabed can be avoided.

Relationship between inertial features of the upper extremity and simple reaction time in boys and girls aged 17–18

The latent period of visual sensor-motor reaction depends, in part, on the sensory and integrative processes in the brain, but is also influenced by the rate of the muscle contraction. There is no clear evidence in the literature whether the rotational inertia of segments of limbs has any direct effect on the reaction time. The aim of our study was to identify this relationship. The study involved 566 right handed students aged 16-17 of both genders beginning their post puberty period. Reaction time was measured during experimental adduction of the forearm and hand, using a special rotating handle and lever connected to a computer that recorded the reaction time (+/- 1 ms). Calculations of the rotational inertia were carried out using regression models by Zatsiorsky and other authors. Each gender group was divided into three subgroups: with high, medium and low values of rotational inertia. It was found that individuals with high values of rotational inertia of forearm and wrist demonstrated significantly longer reaction times. This pattern was apparent in both gender groups. Although males illustrated greater values of rotational inertia than females they demonstrated relatively shorter reaction times. This contradiction can be explained by greater muscle power of young men. We recommend taking into account the amount of rotational inertia of the responsive segment in all kinds of research which require measurement of reaction time.

A Dynamical Approach to an Inertial Forward-Backward Algorithm for Convex Minimization

We introduce a new class of forward-backward algorithms for structured convex minimization problems in Hilbert spaces. Our approach relies on the time discretization of a second-order differential system with two potentials and Hessian-driven damping, recently introduced in [H. Attouch, P.-E. Mainge, and P. Redont, Differ. Equ. Appl., 4 (2012), pp. 27--65]. This system can be equivalently written as a first-order system in time and space, each of the two constitutive equations involving one (and only one) of the two potentials. Its time dicretization naturally leads to the introduction of forward-backward splitting algorithms with inertial features. Using a Liapunov analysis, we show the convergence of the algorithm under conditions enlarging the classical step size limitation. Then, we specialize our results to gradient-projection algorithms and give some illustrations of sparse signal recovery and feasibility problems.

Inertial fusion features in degenerate plasmas

Inertial fusion features in degenerate plasmas

Mechanisms and Implications of Animal Flight Maneuverability

Accelerations and directional changes of flying animals derive from interactions between aerodynamic force production and the inertial resistance of the body to translation and rotation. Anatomical and allometric features of body design thus mediate the rapidity of aerial maneuvers. Both translational and rotational responsiveness of the body to applied force decrease with increased total mass. For flying vertebrates, contributions of the relatively heavy wings to whole-body rotational inertia are substantial, whereas the relatively light wings of many insect taxa suggest that rotational inertia is dominated by the contributions of body segments. In some circumstances, inertial features of wing design may be as significant as are their aerodynamic properties in influencing the rapidity of body rotations. Stability in flight requires force and moment balances that are usually attained via bilateral symmetry in wingbeat kinematics, whereas body roll and yaw derive from bilaterally asymmetric movements of both axial and appendicular structures. In many flying vertebrates, use of the tail facilitates the generation of aerodynamic torques and substantially enhances quickness of body rotation. Geometrical constraints on wingbeat kinematics may limit total force production and thus accelerational capacity in certain behavioral circumstances. Unitary limits to animal flight performance and maneuverability are unlikely, however, given varied and context-specific interactions among anatomical, biomechanical, and energetic features of design.

Intraventricular pressure drop and aortic blood acceleration as indices of cardiac inotropy: a comparison with the first derivative of aortic pressure based on computer fluid dynamics

This paper presents a computational approach to ventricular fluid mechanics to evaluate three inotropic indices of early ejection: the intraventricular pressure drop (Δ p), the first derivative of aortic flow rate (d f/d t) and the first derivative of aortic pressure d p/d t. d p/d t is one of the most frequently used indices for assessing myocardial inotropy. Δ p and d f/d t are characteristic of inertia driven flows and reflect the impulsive nature of the flow inside the ventricle during the ejection phase. The study is based on an axisymmetric fluid dynamics model of the left ventricle, developed according to the finite element approach. The fluid cavity is bounded by a shell containing two sets of counter-rotating contractile fibres. Two simulation sets were performed: the former to investigate the sensitivity of Δ p and d f/d t peaks (Δ p max and d f/d t max) with respect to changes in the inotropic state of the fibre. The latter allows the evaluation of the dependency of Δ p max and d f/d t max on afterload by means of two supravalvular stenoses of 50% and 70%. The model simulates the inertial features of ventricle behaviour. The calculated values of the indices investigated are in close agreement with those reported in the literature. The sensitivities of Δ p max, d f/d t max and d p/d t max are calculated for the two simulation sets. Data are normalised with respect to the maximum values reached in the simulation set. The comparison indicates that Δ p max has a greater sensitivity (3.4 vs. 3.1) and a more linear pattern than d p/d t max for changes in the inotropic state of the fibre. d f/d t max, shows a sensitivity close to d p/d t max. Results confirm that the afterload does not affect d p/d t max, in accordance with experimental observations, while Δ p max and, to a major degree, d f/d t max decrease when the afterload is increased.

On the meaning ofE=mc 2

Einstein's original derivation of the energy-mass relation is re-examined. It is shown that while his conclusion that gamma emission from an excited nucleus must accompany a reduction of the inertial (rest) mass of the nucleus is valid for a structureless particle, it is not necessarily valid when the complex structure of the nucleus is taken into account. In the latter case, in addition to the change in kinetic energy of the entire emitting nucleus that was considered in Einstein's analysis, one must also take account of the change in nuclear configuration energies, from the period before to the period after de-excitation. It is then concluded that the inertial mass of a body (i.e. its resistance to a change of state of motion) of a gamma-emitting nucleus could be exactly the same before and after emission if the internal configuration energy of the nucleus would be correspondingly altered in the process. An experimental test that utilizes the Mossbauer effect is suggested. Einstein's further conclusion that mass is a measure of the energy content of matter is questioned with reference to theconceptual differences between the inertial and energetic features of matter. It is concluded thatE=mc2 is not an identity (i.e. an ‘if-and-only-if’ relation) but it is rather an ‘if-then’ relation, with meaningful connotation only in the local domain, where the formalism of special relativity theory is a useful approximation for a generally relativistic formulation for theories of matter.