This paper deals with the finite element analysis of the demagnetization process of the line start permanent magnet synchronous motor. Special attention has been paid to demagnetization risk assessment after resynchronization during a short-term supply power outage. The current and torque waveforms have been determined assuming the difference depending initial rotor position angle. It has been demonstrated that the highest demagnetization risk occurs when resynchronization (motor reclosing) is performed whe induced electromotive forces are in anti-phase to the supply voltage waveforms. The effect of cage winding resistance on the risk of demagnetization is examined and discussed.
Scattering of sound waves in two stepped cylindrical duct which walls are coated with different acoustically absorbent materials is investigated by using Wiener-Hopf technique directly and by determining scattering matrices. First, by using Fourier transform technique we obtain a couple of modified Wiener-Hopf equations whose solutions involve four sets of infinitely many unknown expansion coefficients providing systems of linear algebraic equations. Then we determine scattering matrices of the problem and we state the total transmitted field by using generalized scattering matrix method. Numerical results are compared for different parameters.
We study an elegant snap system with only one nonlinear term, which is a quadratic nonlinearity. The snap systemdisplays chaotic attractors,which are controlled easily by changing a system parameter. By using analysis, simulations and a real circuit, the dynamics of such a snap system has been investigated. We also investigate backstepping based adaptive control schemes for the new snap system with unknown parameters.
This article presents a wearable system that localizes people in the indoor environment, using data from inertial sensors. The sensors measure the parameters of human motion, tracking the movements of the torso and foot. For this purpose, they were integrated with shirt and the shoe insole. The values of acceleration measured by the sensors are sent via Bluetooth to a smartphone. The localization algorithm implemented on the smartphone, presented here, merges data from the shirt and the shoe to track the steps made by the user and filter out the localization errors caused by movements the shirt and torso. The experimental verification of the algorithm is also presented.
Background: The aim of the study was to determine the predominant learning style and type of intelligence based on the VARK questionnaire and Multiple Intelligences Questionnaire respectively in second year medical students. Determining the relationship between individual preferences of students, based on their learning style and predominant type of intelligence and the perception of the modified Peyton’s four-step approach used to teach cardiac auscultation.
Methods: The opinion of participants 236 of the modified four-step approach was attained through the use of anonymous questionnaires. Using the VARK questionnaire, the participants’ learning style was defined. The predominant type of intelligence was determined by the Multiple Intelligences Question-naire.
Results: The kinesthetic style was the predominant unimodal learning style in second year medical students (in Polish and international students). The most predominant type of intelligence in Polish students was visual-spatial and mathematical and logical, while in international students the predominant types were visual-spatial and mixed type of intelligence. Quantitative analysis indicated that the modified Peyton’s approach is a valuable learning and teaching method for most students, independent of their predominant learning style or intelligence type. The exception was a small group of students with lin-guistic intelligence predominance according to the Multiple Intelligence Questionnaire, for which the Peyton method was more difficult.
Conclusions: This study proves that the modified Peyton’s approach is useful and effective didactic tool and can be successfully applied to most students. This is a new learning strategy for teaching cardiac auscultation in laboratory conditions in classes for a significant majority. Due to the fact that a group of students with a predominance of linguistic intelligence more often perceived the Peyton method to be difficult, it is worth combining traditional methods with new ones in class so that all students, regardless of unimodal learning style or prevailing type of intelligence, are taught satisfactorily.
B a c k g r o u n d: The aim of the study was to evaluate the usefulness of the modified Peyton’s four-step approach in the teaching of cardiac auscultation and to determine students’ perception of Peyton’s four-step approach.
Me t h o d s: The opinion of the participants on the usefulness of the modifi ed four-step approach was attained through the use of anonymous questionnaires, voluntarily completed by students, and on the basis of semi-structured interviews conducted with a subset of students. 187 second-year students of our 6-year long curriculum were enrolled. They attended an obligatory Laboratory Training of Clinical Skills course. The average group size was 16 students.
R e s u l t s: The survey findings identified that 88.1% of participants found it helpful in developing their understanding of cardiac auscultation. 89.8% of all participants claimed that the new modified four-step approach facilitated memorization. The modified Peyton’s four-step method allows for better organization of classes in the opinion of 87.6% students. The advantages of the method were noticed by the majority of students.
C on c l u s i o n s: The modified Peyton’s four-step approach in the teaching of cardiac auscultation under laboratory conditions was perceived by students to be a comprehensible method that facilitates understanding and memorization. Th is approach allows for improved organization of classes. From the student’s perspective this method allows one to master the technique of cardiac auscultation in the classroom, through the increased demand of the participants’ attention, activity and involvement.
Wood plastic composite (WPC) is a lightweight material, resistant against corrosion and damage, with recyclability of consuming materials. These materials usually used in marine structures frequently due to their unique features. In order to strengthen beams made by this material, usually Fibre-reinforced plastic (FRP) sheets are used, and one of the fracture modes in these beams is debonding of FRP sheet from the surface of the beams. To deal with this problem some grooves are used in the surface of the beam to improve the contact surface. The grooves include longitudinal, transverse and diagonal grooves. The main goal of this study is to assess different grooving methods in WPC-FRP beams. In this regard, primarily criteria (improving resistance, performance speed, performance complexity, performance costs, displacement and absorbing energy) were determined through interviews with experts in this field in order to assess the beams. Then, SWARA method employed to evaluate criteria with a policy based perspective and finally EDAS method applied for evaluating related alternatives. Based on obtained results, the longitudinal groove method is the best way of strengthening WPC beams to prevent debonding.