Smart Bio-Impedance-Based Sensor for Guiding Standard Needle Insertion

A venipuncture is the most common non-invasive medical procedure, and is frequently used with patients; however, a high probability of post-injection complications accompanies intravenous injection. The most common complication is a hematoma, which is associated with puncture of the uppermost and lowermost walls. To simplify and reduce complications of the venipuncture procedure, and as well as automation of this process, a device that can provide information of the needle tip position into patient’s tissues needs to be developed. This paper presents a peripheral vascular puncture control system based on electrical impedance measurements. A special electrode system was designed to achieve the maximum sensitivity for puncture identification using a traditional needle, which is usually used in clinical practice. An experimental study on subjects showed that the electrical impedance signal changed significantly once the standard needle entered the blood vessel. On basis of theoretical and experimental studies, a decision rule of puncture identification based on the analysis of amplitude-time parameters of experimental signals was proposed. The proposed method was tested on 15 test and 9 control samples, with the results showing that 97% accuracy was obtained.

The influence of different game formats on technical actions and playing time parameters – A study with under-7 and under-9 soccer players in a competitive context

Soccer competitions in childhood should ensure a high involvement of all players regardless of their talent. The purpose of the present study was to compare soccer players’ technical actions and playing time parameters in 7v7 in comparison to 3v3 (on mini-goals without goalkeepers; under-7) and 5v5 (on 1.65 × 5 m. goals with goalkeepers; under-9) game formats in a competitive context. Using a quasi-experimental within-subject design, tournaments with under-7 ( n = 42) and under-9 ( n = 43) players were conducted. Technical actions and playing time parameters were rated. Based on the total number of technical actions in 7v7, median splits of the samples were conducted to compare differences between high-involved (dominant) and low-involved (non-dominant) players. No differences in the effective playing time comparing game formats within the age groups were found. In total, 7884 technical actions were rated. In both age groups, the total number of technical actions was higher in the smaller game formats. In under-7, the number of technical actions in all variables was higher in 3v3. In under-9, the number of technical actions was also higher in 5v5 except for unsuccessful passes as well as successful 1v1 situations. More unsuccessful 1v1 situations were found in 7v7. Concerning the total number of technical actions, both dominant and non-dominant players in both age groups performed more technical actions in small-sided games. Due to the higher involvement of the children, better conditions for the acquisition of soccer-specific skills in the smaller game formats compared to 7v7 game formats can be concluded.

A Hybrid Approach for Feature Selection Based on Correlation Feature Selection and Genetic Algorithm

In today's world, machine learning has become a vital part of our lives. When applied to real-world applications, machine learning encounters the difficulty of high dimensional data. Unnecessary and redundant features can be found in data. The performance of classification algorithms employed in prediction is harmed by these superfluous features. The primary step in developing any decision support system is to identify critical features. In this paper, authors have proposed a hybrid feature selection method CFGA by integrating CFS (Correlation feature selection) and GA (genetic algorithm). The efficiency of proposed method is analyzed using Logistic Regression classifier on the scale of accuracy, sensitivity, specificity, precision, F-measure and execution time parameters. Proposed CFGA method is also compared to six other feature selection methods. Results demonstrate that proposed method have increased the performance of the classification system by removing irrelevant and redundant features.

Fluid relaxation and retardation time properties in the flow of Burgers fluid subject to modified heat and mass flux theory

In this study, the heat transport is scrutinized in the flow of magnetized Burgers fluid accelerated by stretching cylinder. Rather than, classical Fourier's and Fick's laws, the Cattaneo-Christov theory featuring the improved heat and mass conduction is utilized to investigate the energy transport. Further, the transport of thermal and solutal energy is controlled by the significant influence of heat generation/absorption and chemical reaction. The physical flow problem is modelled in the form of partial differential equations (PDEs) which are then transformed into the non-linear ordinary differential equations (ODEs) by invoking appropriate similarity variables. The numerical simulation to the system of ODE's is tackled by employing BVP-Midrich scheme in Maple. The numerical results for flow field, thermal and concentration distributions are exhibited graphically. The impact of fluid relaxation and retardation time parameters on the velocity field are observed in growing and decaying way, respectively. Both the thermal and solutal energy transport decline with higher values of retardation time parameter. The rise in Burgers fluid parameter enhances the transport of energy during the fluid motion. The effect of thermal and solutal relaxation time parameters on heat and mass transport in the fluid are noticed in the declining manner.

Influence of COVID-19 Pandemic in Students’ Distribution of Time in Distant Learning

Statistical analysis offers unprecedented opportunities to identify learning strategies. This fact has been boosted in the COVID-19 pandemic because of the data obtained in distant learning scenarios due to the confinement. This article deals with the identification of students’ strategies in different distant learning scenarios such as working autonomously as a support for face-to-face classes or learning autonomously in COVID-19 confinement. We have measured the influence of parameters such as the time they spent in self-evaluation, the scores obtained through this process and the distribution of time when studying autonomously. We have only detected significant results that guide to a better learning strategy when we include time parameters, such as the time between studying sessions or the time between students’ first session and their final exam. We demonstrate that students that started to study earlier and more dispersed get better success ratio (not necessarily better scores) than those that started later and do it more concentrate. The findings from this study suggest that the same amount of time spent in autonomous learning optimizes its effectiveness when it is extended in time. This learning strategy was found more often in COVID-19 confinement, where students were forced to stay at home.

Improving 3D Path Tracking of Unmanned Aerial Vehicles through Optimization of Compensated PD and PID Controllers

The development of quadrotor unmanned aerial vehicles (QUAVs) is a growing field due to their wide range of applications. QUAVs are complex nonlinear systems with a chaotic nature that require a controller with extended dynamics. PD and PID controllers can be successfully applied when the parameters are accurate. However, this parameterization process is complicated and time-consuming; most of the time, parameters are chosen by trial and error without guaranteeing good performance. The originality of this work is to present a novel nonlinear mathematical model with aerodynamic moments and forces in the Newton–Euler formulation, and identify metaheuristic algorithms applied to parameter optimization of compensated PD and PID controls for tracking the trajectories of a QUAV. Eight metaheuristic algorithms (PSO, GWO, HGS, LSHADE, LSPACMA, MPA, SMA and WOA) are reported, and RMSE is used to measure each dynamic performance of the simulations. For the PD control, the best performance is obtained with the HGS algorithm with an RMSE = 0.037247252379126. For the PID control, the best performance is obtained with the HGS algorithm with an RMSE = 0.032594309723623. Trajectory tracking was successful for the QUAV by minimizing the error between the desired and actual dynamics.

Increasing of the Accuracy of Signalsʼ Time Parameters Measuring Using Double Pulse Trains

In modern diagnostics, much attention is paid to measuring of time parameters, as well as their change over time. The purpose of this work is to develop a method for measuring of time intervals which made it possible to increase the measurement accuracy by reducing errors associated with the instability of main parameters of the pulse signal.In the most of approaches used, the error associated with the instability of main parameters of signals under study is not enough taken into account. As an alternative, a spectral method is proposed in which the measurement of time intervals, as well as their changes, is performed based on the analysis of pulse sequences formed on the basis of characteristic points of the measured signal. For this a double pulse sequence was considered, an equation for the amplitudes of its spectral components was obtained, and in accordance with this it was determined that the delay time between double pulses is the most informative parameter.Using the Mathcad software, an analysis of the sensitivity regions was carried out for the change in the main parameters of the pulse sequence, namely the repetition rate, as the main destabilizing factor.As a result of the implementation of the developed technique, a structural diagram of the measuring system is proposed and an analysis of the measurement error associated with the instability of the main parameters of the pulse sequence is carried out. This error is estimated to be less than 0.01 %.The considered method makes it possible to increase the accuracy of measuring time intervals due to the almost complete elimination of the influence of the instability of the reference frequency and the amplitude of the generated pulses which is unattainable with modern hardware, including digital signal processing.

Cosmic censorship, massless fermionic test fields, and absorption probabilities

In the conventional approach, fermionic test fields lead to a generic overspinning of black holes resulting in the formation of naked singularities. The absorption of the fermionic test fields with arbitrarily low frequencies is allowed for which the contribution to the angular momentum parameter of the space-time diverges. Recently we have suggested a more subtle treatment of the problem considering the fact that only the fraction of the test fields that is absorbed by the black hole contributes to the space-time parameters. Here, we re-consider the interaction of massless spin (1/2) fields with Kerr and Kerr–Newman black holes, adapting this new approach. We show that the drastic divergence problem disappears when one incorporates the absorption probabilities. Still, there exists a range of parameters for the test fields that can lead to overspinning. We employ backreaction effects due to the self-energy of the test fields which fixes the overspinning problem for fields with relatively large amplitudes, and renders it non-generic for smaller amplitudes. This non-generic overspinning appears likely to be fixed by alternative semi-classical and quantum effects.

FDA-MIMO Beampattern Synthesis with an Analytical Method

Since the beampattern has the characteristics of range-angle dependence, frequency diverse array multiple-input multiple-output (FDA-MIMO) radar has a good application prospect. There have been many studies to improve the performance of the beampattern by optimizing the frequency offset. However, on the basis of fully understanding the time parameters, the relationship between the array element frequency offset and the beampattern performance still needs to be clarified. Based on a new FDA-MIMO radar framework, this paper presents an analytical solution of the beampattern, which removes the influence of the time parameter. Taking the minimum main lobe as the objective function, an analytical method for solving a better frequency offset is given. Then, a method of using the window function was proposed to reduce the high side lobes of the range dimension. Comparing with the existing FDA radar beampattern design methods, it can achieve a more focusing beampattern. The simulation results verify the correctness of the theory.