On the constraints violation in forward dynamics of multibody systems

It is known that the dynamic equations of motion for constrained mechanical multibody systems are frequently formulated using the Newton-Euler’s approach, which is augmented with the acceleration constraint equations. This formulation results in the establishment of a mixed set of partial differential and algebraic equations, which are solved in order to predict the dynamic behavior of general multibody systems. The classical resolution of the equations of motion is highly prone to constraints violation because the position and velocity constraint equations are not fulfilled. In this work, a general and comprehensive methodology to eliminate the constraints violation at the position and velocity levels is offered. The basic idea of the described approach is to add corrective terms to the position and velocity vectors with the intent to satisfy the corresponding kinematic constraint equations. These corrective terms are evaluated as function of the Moore-Penrose generalized inverse of the Jacobian matrix and of the kinematic constraint equations. The described methodology is embedded in the standard method to solve the equations of motion based on the technique of Lagrange multipliers. Finally, the effectiveness of the described methodology is demonstrated through the dynamic modeling and simulation of different planar and spatial multibody systems. The outcomes in terms of constraints violation at the position and velocity levels, conservation of the total energy and computational efficiency are analyzed and compared with those obtained with the standard Lagrange multipliers method, the Baumgarte stabilization method, the augmented Lagrangian formulation, the index-1 augmented Lagrangian and the coordinate partitioning method.The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Polska, Ukraina, świat

Od Wydawcy: "Krakowska Szkoła Wyższa im. Andrzeja Frycza Modrzewskiego, największa niepubliczna szkoła wyższa w Małopolsce od początku swego powstania przywiązuje wagę do kontaktów z uczelniami zagranicznymi. Współpraca nawiązana z wieloma partnerami zagranicznymi nie tylko pozwoliła kadrze dydaktycznej i studentom Frycza nawiązać interesujące kontakty naukowe i biznesowe, wzbogacić księgozbiór o specjalistyczne publikacje, ale zaowocowała także wieloma cennymi programami. Współpraca Szkoły z Międzynarodowym Uniwersytetem REG I im. Akademika Stepana Demianczuka w Równem na Ukrainie - pierwszym partnerem zagranicznym, z którym umowę podpisano w grudniu roku 2001 - przebiega na wielu płaszczyznach (wymiana studentów i pracowników, udział w konferencjach, wspólne publikacje). Owocem jej je st też poniższa książka Polska, Ukraina, Świat pod redakcją Klemensa Budzowskiego i Anatolija Stiepanowicza Demianczuka, zawierająca dorobek naukowy pracowników obu uczelni."(...

Body composition and Hashimoto disease

Background. Body weight or BMI do not provide any information about the content of muscle tissue, water content, body fat and its distribution in the body. Thyroid dysfunction is associated with a change in body weight, but also its composition regardless of physical activity. Objective. The aim of the study was to compare the body composition of female patients diagnosed with Hashimoto's disease (HD) and the body composition of healthy women who have never been treated before due to thyroid diseases. Materials and methods. The study involved 47 women diagnosed with Hashimoto disease (HD) and 65 women declaring good health. Body mass and height and body composition analysis using bioelectrical impedance analysis were performed using the TANITA multi-frequency segmental body composition analyzer. Variables having a distribution similar to the normal distribution were analyzed by the analysis of variance (ANOVA), otherwise the Kruskal-Wallis test was used. Results. Women with Hashimoto disease were characterized by significantly higher values of body weight, and thus BMI index, than healthy women (respectively 73.64 kg vs. 64.36 kg, p <0.0001; 27.65 kg/m2 vs. 23.95 kg/m2, p <0.001).The problem of excess body fat in the body statistically significantly more often affected women with Hashimoto disease than healthy women (44.7% vs. 13.8%, p <0.001). Conclusions. The results regarding the weight and composition of the patients treated for thyroid disease indicate the need for further in-depth analyses. Even small abnormalities of the thyroid function in the range of reference values may result in the development of many adverse changes in the body

Assessment of caffeine intake with food by Polish females and males

Background. Caffeine is the most widespread psychoactive substance in the world. With long-term consumption of caffeinated beverages, there is a high probability of overtaking on caffeine. Objective. The aim of the study was to estimate the consumption of caffeine in the daily caffeine intake of Polish consumers, determine the caffeinated products in the intake of this substance. Materials and methods. The survey was completed by 433 respondents living in Poland. The research tool was the electronic questionnaire, which consisted of: a) questions about personal data and measurement anthropometric and the level of physical activity and smoking; b) questions regarding the portion size and frequency of consumption of coffee, tea, cocoa, chocolate, energy drinks and colacarbonated beverages. Results. The main sources of caffeine in the respondents' diet include: coffee (Me 43.64 mg/d) and tea (Me 37.60 mg/d). Approximately 20% of respondents exceeded the threshold of daily caffeine intake (safety level for children and adolescents up to 3 mg/kg b.w, for adults up to 5.7 mg/kg b.w), considered safe. Conclusions. Respondents who have crossed the safe dose of caffeine intake, should limit the consumption of products being its main source (coffee

Failure of skeleton timber structure of swimming pool walls

W artykule przedstawiono opis konstrukcji parterowego budynku basenu kąpielowego wykonanego w technologii szkieletu drewnianego. W wyniku błędów projektowych i wykonawczych, po kilku latach użytkowania obiektu wystąpił stan awaryjny konstrukcji nośnej szkieletu spowodowany butwieniem drewna. Przedstawiono sposób wymiany uszkodzonych elementów oraz jego realizację.Structure of one floor building of swimming pool realized as a skeleton made out of timber is presented. Failure of structure was a result of decay of wood after just few years of exploitation. Paper presents a realization of damage repair

Examples of damages of detached houses built-up area due to tornado in Kalina village

W artykule przedstawiono przykłady uszkodzeń budynków mieszkalnych i gospodarczych, stanowiących zwartą zabudowę jednorodzinną, w wyniku działania trąby powietrznej 15 sierpnia 2008 r.This paper presents the examples of damages of residential and farm buildings forming the compact built-up area, due to tornado in 15th August 2008

Causes of building catastrophe of residential-service building

W artykule przedstawiono opis katastrofy budowlanej powstałej w wielokondygnacyjnym budynku usługowo-mieszkalnym pochodzącym z przełomu XIX i XX wieku. Katastrofa powstała podczas prowadzonych robót budowlanych mających na celu zmianę sposobu użytkowania usługowych pomieszczeń parteru. Opisano zakres prowadzonych robót oraz popełnione błędy projektowe i wykonawcze, które doprowadziły do katastrofy.In this article was presented the catastrophe of residential-service building which was built in the late 19th and early 20th centuries. The collapse of the building began during refurbishment building works which aimed to change the usage of the ground floor of building. In this paper were presented the scope of building works as well as design and execution faults which caused the catastrophe