Exact controllability of non-Lipschitz semilinear systems

We present sufficient conditions for exact controllability of a semilinear infinite-dimensional dynamical system. The system mild solution is formed by a noncompact semigroup and a nonlinear disturbance that does not need to be Lipschitz continuous. Our main result is based on a fixed point-type application of the Schmidt existence theorem and illustrated by a nonlinear transport partial differential equation

A finite element model for abrasive waterjet machining

This paper presents a first attempt to model abrasive waterjet (AWJM) machining process using the powerful tool of the finite element method (FEM) in order to explain the abrasive particle-workpiece interaction. The new model takes into account precise representation of the constitutive behaviour of the workpiece material under AWJ dynamic loading conditions which was ignored in previous AWJM models. In the present model, forces acting on the abrasive particle need not be initially determined, as in previous AWJM studies, as they are automatically calculated at each time step. The results show that the finite element method is a useful tool in predicting abrasive-material interaction and AWJ depth of cut.Modelowanie obróbki strumieniem wodnościernym metodą elementów skończonych. W artykule przedstawiono pierwsze podejście do modelowania obróbki strumieniem wodnościernym metodą elementów skończonych. Celem badań jest próba wyjaśnienia zjawisk występujących na styku ścierniwa i przedmiotu obrabianego. Ten nowy model w sposób precyzyjniejszy uwzględnia właściwości materiału poddanego dynamicznym obciążeniom, co we wcześniejszych modelach nie było uwzględniane. W modelu tym nie trzeba definiować początkowej siły działającej na ścierniwo (jak to miało miejsce w poprzednich modelach), ponieważ jest ona automatycznie obliczana w każdym kroku czasowym. Wyniki symulacji pokazują, że MES jest bardzo dobrym narzędziem do przewidywania reakcji pomiędzy ścierniwem i przedmiotem obrabianym oraz głębokości skrawania

ULTRASONIC LIGHT DIFFRACTION FOR THE CASE OF THE INTENSE LASER BEAM GENERATING A 3rd HARMONIC IN LIQUIDS

Un calcul de la diffraction par une onde ultrasonore de la lumière intense émise par un laser est exposé dans le cas du sulfure de carbone, du tétrachlorure de carbone et du benzène. Des essais ont été effectués pour trouver les conditions expérimentales qui confirment les prévisions théoriques.Some calculations of the intensity distributions of intense laser light diffracted on an ultrasonic wave were made for carbon disulfide, carbon tetrachloride and benzene. Attempts have been made to find some proper conditions for the experiment to prove theoretical predictions

Effects of anthropometric factors on postural stability in individuals with hearing impairment

Identification of factors that affect postural stability may help to improve diagnostic accuracy and enhance the quality of treatment and rehabilitation. This study sought to assess the relationship between postural stability parameters and anthropometric factors of persons with hearing impairment (HI). Methods: The study included 128 individuals – 42 subjects with HI and 86 without HI (healthy controls). Research methodology included an interview and a medical examination, anthropometric measurements and stabilometric tests on platforms with stable and unstable surfaces. Results: In the group of female study participants with HI, significant correlations were only noted between body height and the Fall Risk Index (FRI). In the group of male subjects with HI, the study revealed significant correlations between FRI and body mass, BMI, % MM (muscle mass percentage) and % FAT (fat percentage). Moreover, moderate correlation was found between COP path with eyes open and body mass, while high correlation was observed between COP path with eyes open and BMI, % MM and % FAT. No significant correlation was noted between FRI and body height in men with HI. Conclusions: The examination of correlations between postural stability and body build of persons with HI did not confirm the effects of body height on postural stability in the examined group of individuals with HI, but revealed a greater influence of somatic parameters (body mass, BMI, % MM, % FAT) on postural stability in hearing-impaired men

Anaerobic variables as specific determinants of functional classification in wheelchair basketball

Every parasport is currently encouraged to consider evidence-based classification to develop their respective classification system. Therefore, the aims of this study were to: (1) assess the relationship between trunk function and anaerobic power determining proficiency in wheelchair basketball, and (2) define “natural classes” in wheelchair basketball based on anaerobic power. Fifty-nine elite players (representing five national teams) were divided into four main functional classes: Group 1 (n=17), Group 2 (n=14), Group 3 (n=16), Group 4 (n=12). They performed the 6x10s Anaerobic Power Test using an arm crank ergometer. Average values of mean power, peak power, relative mean power, relative peak power, and power decrement were calculated for the 6x10s and 3x10s tests. The Spearman’s correlation matrix revealed significant correlations between classes and values recorded in the 6x10s test. This confirmation between anaerobic power and players’ classification endorses the division of players into different classes. Furthermore, cluster analysis (with fair quality) divided players into two “natural classes”. The first resulting class was mainly formed of participants from Group 1 (71%). An important complement to this research could be to consider wheelchair acceleration and the volume of trunk action in wheelchair basketball classification