Dragging spin-orbit-coupled solitons by a moving optical lattice

It is known that the interplay of the spin-orbit-coupling (SOC) and mean-field self-attraction creates stable two-dimensional (2D) solitons (ground states) in spinor Bose-Einstein condensates. However, SOC destroys the system's Galilean invariance, therefore moving solitons exist only in a narrow interval of velocities, outside of which the solitons suffer delocalization. We demonstrate that the application of a relatively weak moving optical lattice (OL), with the 2D or quasi-1D structure, makes it possible to greatly expand the velocity interval for stable motion of the solitons. The stability domain in the system's parameter space is identified by means of numerical methods. In particular, the quasi-1D OL produces a stronger stabilizing effect than its full 2D counterpart. Some features of the domain are explained analytically.

ANALYSIS OF THE PARAMETERS OF DYNAMIC SUPERPLASTICITY THE INDUSTRIAL ALUMINUM ALLOYS

The problem of determining the features of the development of blurred phase transitions observed under conditions of dynamic superplasticity of aluminum alloys is solved using the specific heat capacity function. Within the framework of the developed model representations, the deformation mechanisms characteristic of superplasticity and boundary metastable states are analyzed using the Fokker-Planck equation. Using a macrokinetic model, an explicit expression is obtained for the function that characterizes the mechanism of grain boundary slippage (the “drift " coefficient) that prevails in superplasticity. By integrating the differential equations resulting from the model, the solution of which establishes the type of functions responsible for the implementation of the mechanisms of grain boundary slippage and diffusion processes. It is proposed that the diffusion coefficient is responsible for the accumulation of irreversible deformations outside the velocity range of superplasticity. The function responsible for the effects of grain boundary slippage (the "drift" coefficient) is particularly active towards the middle of the superplasticity velocity interval. It is confirmed that outside the velocity range of superplasticity, there is a redistribution of mass transfer forms, the responsibility for which is assigned to the diffusion coefficient. It is shown that the diffusion function shows a tendency to decrease when approaching the range of superplasticity rates. Metastable states are characterized by the competition of diffusion mechanisms and grain boundary slippage.

A review of foot pose and trajectory estimation methods using inertial and auxiliary sensors for kinematic gait analysis

The use of foot mounted inertial and other auxiliary sensors for kinematic gait analysis has been extensively investigated during the last years. Although, these sensors still yield less accurate results than those obtained employing optical motion capture systems, the miniaturization and their low cost have allowed the estimation of kinematic spatiotemporal parameters in laboratory conditions and real life scenarios. The aim of this work was to present a comprehensive approach of this scientific area through a systematic literature research, breaking down the state-of-the-art methods into three main parts: (1) zero velocity interval detection techniques; (2) assumptions and sensors’ utilization; (3) foot pose and trajectory estimation methods. Published articles from 1995 until December of 2018 were searched in the PubMed, IEEE Xplore and Google Scholar databases. The research was focused on two categories: (a) zero velocity interval detection methods; and (b) foot pose and trajectory estimation methods. The employed assumptions and the potential use of the sensors have been identified from the retrieved articles. Technical characteristics, categorized methodologies, application conditions, advantages and disadvantages have been provided, while, for the first time, assumptions and sensors’ utilization have been identified, categorized and are presented in this review. Considerable progress has been achieved in gait parameters estimation on constrained laboratory environments taking into account assumptions such as a person walking on a flat floor. On the contrary, methods that rely on less constraining assumptions, and are thus applicable in daily life, led to less accurate results. Rule based methods have been mainly used for the detection of the zero velocity intervals, while more complex techniques have been proposed, which may lead to more accurate gait parameters. The review process has shown that presently the best-performing methods for gait parameter estimation make use of inertial sensors combined with auxiliary sensors such as ultrasonic sensors, proximity sensors and cameras. However, the experimental evaluation protocol was much more thorough, when single inertial sensors were used. Finally, it has been highlighted that the accuracy of setups using auxiliary sensors may further be improved by collecting measurements during the whole foot movement and not only partially as is currently the practice. This review has identified the need for research and development of methods and setups that allow for the robust estimation of kinematic gait parameters in unconstrained environments and under various gait profiles.

Influence of the delamination loading velocity on textile bonds and sewn seams strength

Purpose The purpose of this paper is to determine the influence of the loading velocity on textile bonds and sewn seam strength. Design/methodology/approach Commercially produced polyamide and polyester knitted fabric, and polyester woven fabrics as well as three commercially available monolayer urethane thermoplastic films were used in this research. Two layers of each fabric were laminated at 160°C temperature at 5.6 kPa for 20 seconds. Sewn specimens were joined applying (301) and (514) stiches for woven and knitted fabrics, respectively. The bond and sewn seam strength was investigated at different delamination loading velocities (50, 100, 150, 200, 300 mm/min). These values of velocities lies in the velocity interval which covers the different standard requirements for testing of the quality of textiles and their seams or were applied in the research works of previous scientists. As the influence of loading velocity was more significant for bond strength, the bond strength results were analyzed together with the analysis of bond rupture character. Findings The determined influence of the loading velocity on textile bonds strength has proved that the loading velocity in bond strength test is of high importance for the prediction of the behavior of clothing being in exploitation under different conditions. The opposite tendency was determined for the sewn seams, the strength of which was independent on loading velocity. Originality/value The influence of the loading velocity on textile bond and sewn seam strength was not analyzed in the previous research works published by other scientists. It was known that the standard velocity is 50 mm/min for seams and 100 mm/min for textiles strength testing. It was shown there that the real exploitation of a garment as a whole complicated heterogenic dynamic system could be simulated with changing loading velocities during their seam strength testing. It was also determined that the loading velocity makes different influence on bonded and sewn seams of textiles.

An Improved Clutter Suppression Method for Weather Radars Using Multiple Pulse Repetition Time Technique

This paper describes the implementation of an improved clutter suppression method for the multiple pulse repetition time (PRT) technique based on simulated radar data. The suppression method is constructed using maximum likelihood methodology in time domain and is called parametric time domain method (PTDM). The procedure relies on the assumption that precipitation and clutter signal spectra follow a Gaussian functional form. The multiple interleaved pulse repetition frequencies (PRFs) that are used in this work are set to four PRFs (952, 833, 667, and 513 Hz). Based on radar simulation, it is shown that the new method can provide accurate retrieval of Doppler velocity even in the case of strong clutter contamination. The obtained velocity is nearly unbiased for all the range of Nyquist velocity interval. Also, the performance of the method is illustrated on simulated radar data for plan position indicator (PPI) scan. Compared with staggered 2-PRT transmission schemes with PTDM, the proposed method presents better estimation accuracy under certain clutter situations.