Інтерактивний контроль при формоутворенні багатогабаритних деталей

Physical phenomenon of warping (springing) can be observed as a technological heritage after large-dimensional articles forming or curing and consequent cooling of composite articles. This phenomenon can be seen as gaps between ready article contour and forming jig contour. Deviation degree of ready article surface from theoretical contour and article dimensions has to be controlled during manufacturing. Application of auxiliary controlling jig leads to expenses and labor-manufacturability increasing. Possibility of application forming jig with inserted jet gages is considered for articles shape controlling. Such gages and realization of acoustic methods allow to control not only final article shape but also geometry on intermediate stages of manufacturing.Після формоутворення багатогабаритних листових деталей з листових механічних заготовок або полімеризації і охолодження деталей з композитних матеріалів проявляється технологічна спадковість у вигляді викривлення (пружнення). Це спостерігається у вигляді неприлягання готової деталі до формозадаючої поверхні технологічного оснащення. При контролі якості формозміни необхідно вимірювати ступінь порушення форми і розмірів. Застосування контрольної оснастки дорого і складно. Розглянуто можливість використання для контролю формозадаючої оснастки з встановленими в ній повітряними струминними датчиками. Такі датчики і застосування акустичних методів дозволяють контролювати не тільки кінцеву форму заготовки, а й форму заготовки на попередваріантних етапах формозміни

Propagation of gravitational waves in multimetric gravity

We discuss the propagation of gravitational waves in a recently discussed class of theories containing N >= 2 metric tensors and a corresponding number of standard model copies. Using the formalism of gauge-invariant linear perturbation theory we show that all gravitational waves propagate at the speed of light. We then employ the Newman-Penrose formalism to show that two to six polarizations of gravitational waves may exist, depending on the parameters entering the equations of motion. This corresponds to E(2) representations N_2, N_3, III_5 and II_6. We finally apply our general discussion to a recently presented concrete multimetric gravity model and show that it is of class N_2, i.e., it allows only two tensor polarizations, as it is the case for general relativity. Our results provide the theoretical background for tests of multimetric gravity theories using the upcoming gravitational wave experiments.Comment: 21 pages, no figures, journal versio

Reconsiderando el significado de Hogar en la Rehabilitación: hacia una ciudad histórica sostenible

Despite the significant literature about the meaning of home and the scholars’ research concerning the home environment, the concept of home didn’t filter into the rehabilitation process. The conservation theory and the rehabilitation methodology are still concentrating on the material aspects of the built environment and ignoring the immaterial aspects and meanings. In view of that the dwellings are not only artifacts but they are a livable example of the social structure and behavioral patterns. Understanding the dwellers relationship with their dwellings will be helpful in establishing a connection between the rehabilitation of the historical domestic architecture and the concept of home. This requires reconsidering the theoretical frame work of the rehabilitation process so as to be able to recognize the change in the historical house’s spatial structure and order and to link them to the social structure and pattern of use.A pesar de la gran cantidad de literatura sobre el significado del hogar y las investigaciones hechas por académicos sobre el ambiente del hogar, el concepto de hogar no se filtró en el proceso de rehabilitación. La teoría de la conservación y la metodología de rehabilitación siguen concentrándose en los aspectos materiales del ambiente construido e ignoran los aspectos inmateriales. Tomando en cuenta que las viviendas no son sólo objetos, sino ejemplos de estructuras sociales, y patrones de conducta, el entendimiento de la relación entre habitantes y sus viviendas será de utilidad para establecer una conexión entre la rehabilitación de la arquitectura doméstica histórica y el concepto del hogar. Para ello es necesario reconsiderar el marco de trabajo teórico del proceso de rehabilitación con el fin de ser capaz de reconocer el cambio en la estructura espacial del hogar histórico y el orden, y vincularlos a la estructura social

Time-Resolved Temperature Measurements in a Shock Tube Facility

This paper presents non-intrusive, time-resolved temperature measurements in the post-shock flow within a shock tube. We detail the technique, characterise its sensitivity to noise at various pressures, and present temperature measurements after the incident shock wave. Comparisons of experimental measurements with analytical correlations show good agreement with calculated post-shock temperatures at measurement rates of 1 kHz, but systematic errors occur at scan frequencies of 3 kHz, due to the limited bandwidth of our current detector system

Non-linear MPC for winding loss optimised torque control of anisotropic PMSM

For a non-linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross-coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look-up-tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller

Non-linear MPC for winding loss optimised torque control of anisotropic PMSM

For a non-linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross-coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look-up-tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller

Stiffness Optimized Multi-Robot Behavior Planning using Reduced Hessian Method

Stiffness is a critical weakness in robot-driven manufacturing. Following the idea of enhancing stiffness by physically coupling multiple robots, the cooperative behavior should be optimized. We present a reduced Hessian method to generate stiffness optimized placement and motion for coupled robots with given manufacturing processes. To improve efficiency the search space dimension of the optimization problem is reduced while the high-dimensional path and coupling constraints are satisfied in each iteration. By integrating a stiffness model in the optimization, cooperative behavior with stiffness enhancement is generated. The results are validated by experiments for both 7-axis and 6-axis robots with physical coupling

Effects of jamming on non-equilibrium transport times in nano-channels

Many biological channels perform highly selective transport without direct input of metabolic energy and without transitions from a 'closed' to an 'open' state during transport. Mechanisms of selectivity of such channels serve as an inspiration for creation of artificial nano-molecular sorting devices and bio-sensors. To elucidate the transport mechanisms, it is important to understand the transport on the single molecule level in the experimentally relevant regime when multiple particles are crowded in the channel. In this paper we analyze the effects of inter-particle crowding on the non-equilibrium transport times through a finite-length channel by means of analytical theory and computer simulations

Bias-free Parameter Identification of a Fractional Order Model

This paper deals with the parameter identification of a fractional system considering a noisy observation of the output signal. The novelty is that the instrumental variable method is applied to the modulating function method applied to a fractional system. A simulated output signal which is not correlated to noise is required as the instrumental variable. Because all known simulation algorithms only consider zero initial conditions, the simulated output signal converges against the true output signal in an undefined time if the zero initial conditions are penalized. Therefore, an algorithm is extended with the short-memory principle. The benefit is that after a fixed time the error between the simulated and true output signal is small and can be used as the instrumental variable. Considering this extension of the simulation algorithms, it is shown that a consistent estimation is yield with the instrumental variable method

Post-Newtonian limit of teleparallel Horndeski gravity

We consider the newly proposed Bahamonde–Dialektopoulos–Levi Said (BDLS) theory, that is the Horndeski analog in the teleparallel framework and thus contains a non-minimally coupled scalar field, including higher order derivatives, that leads however to second order field equations both for the tetrad and the scalar field. This theory was mostly constructed to revive those models that were severely constrained in the scalar–tensor version of the theory from the GW170817, but includes also much richer phenomenology because of the nature of the torsion tensor. For this theory we determine the parameterized post-Newtonian (PPN) limit, calculate the full set of post-Newtonian parameters and highlight some special cases