Implementation of piezoelectric coupled electro-mechanica behavior for damage detection in engineering structures

Assessment of the structural condition plays an important role in determining structural reliability. Development of systems which can monitor structural condition should lead to improved structural safety and reliability. Damage detection is a crucial issue in structural health monitoring and represents therefore an important focus of the research interest over the past years. In this work we present the methodology based on implementation of active piezoelectric materials embedded in or attached to engineering structures, which can successfully be implemented for detection of possible damages owing to their coupled electro-mechanical behavior. Here particularly we are focused on piezoelectrically induced wave propagation through concrete structures, with the aim of damage detection. The method presented here is based on determination of damage indices which reflect the energy variations of the output piezoelectric sensor signals. Due to wave energy change in directions between actuators and sensors in the presence of a damage it is possible to locate the damage by overlaying the images of the damage indices in different directions. Implementation of the method is documented by examples

Optimal actuator and sensor placement with regard to coupled electro-mechanical behaviour of smart structures

In this paper the problem of optimal actuator and sensor placement for active large flexible structures is considered. The proposed placement optimization method is based on balanced reduced models. It overcomes disadvantages arising from demanding numeric procedures related with high order structural models. Optimization procedure relies on H2 and H∞ norms, as well as on controllability and observability Gramians, related with structural eigenmodes of interest. The optimization procedure is documented by examples, which show a good agreement between the results obtained using different placement indices

Numerical modelling of coupled electro-mechanical problems for the state space controller design

Model development for coupled electro-mechanical problems in light-weight smart structure design is the subject of this paper. The paper addresses development of reliable models for the controller design of piezoelectric smart structures and systems, within an overall design procedure. Model development is based on the finite element (FE) approach, with application of modal reduction techniques for obtaining the state space models convenient for the controller design. Modal truncation and balanced modal reduction are considered as modal reduction techniques, with regard to controllability and observability issues. From the model optimization and verification point of view the experimental modal analysis and identification issues are addressed as well. Examples of model application to controller design document the feasibility of the technique

Application of 3D animation principles and tools in geometrical education

Geometrical education using 3D animation principles and tools represents a new methodology approach and its final result is presented on new way, as multimedia tool. The originality of the paper is based on interdisciplinary approach and use of new technologies. The method derived from the overlap of multiple disciplines such as architecture, structural systems, descriptive geometry, computer animation and programming. Teamwork is comprised of different disciplines since the authors working in different domains of architectural studies. This paper is presented as a visual dynamic educational tool for students of technical and applied arts faculties. The aim is to simplify the perception of geometric forms and the process of their construction. The results leads to the production of geometry with complex topology and could be more developed. So, the results are multilayered, and are the solid basis for further scientific research and further development in practice. The geometrical education target group is the students of the technical and art faculties. It is necessary to emphasize that this work is the beginning of our further scientific research papers in different areas due to an interdisciplinary approach. These areas are: geometrical education, pedagogical theory and psychological aspects of teaching and experimental design in architecture. Aspects and research results presented in this paper are: the basic structure of multimedia learning aid, production methodology, and the final application in education

Application of 3D animation principles and tools in geometrical education

Geometrical education using 3D animation principles and tools represents a new methodology approach and its final result is presented on new way, as multimedia tool. The originality of the paper is based on interdisciplinary approach and use of new technologies. The method derived from the overlap of multiple disciplines such as architecture, structural systems, descriptive geometry, computer animation and programming. Teamwork is comprised of different disciplines since the authors working in different domains of architectural studies. This paper is presented as a visual dynamic educational tool for students of technical and applied arts faculties. The aim is to simplify the perception of geometric forms and the process of their construction. The results leads to the production of geometry with complex topology and could be more developed. So, the results are multilayered, and are the solid basis for further scientific research and further development in practice. The geometrical education target group is the students of the technical and art faculties. It is necessary to emphasize that this work is the beginning of our further scientific research papers in different areas due to an interdisciplinary approach. These areas are: geometrical education, pedagogical theory and psychological aspects of teaching and experimental design in architecture. Aspects and research results presented in this paper are: the basic structure of multimedia learning aid, production methodology, and the final application in education

Estrategias de afrontamiento ante el duelo por pérdida de un miembro familiar

La muerte representa un tema tabú debido al dolor que suscita. Esto ha generado que no se aborde con la profundidad necesaria; y que, ante la pérdida de un ser querido, las personas se sientan frente a una situación novedosa sin estrategias que les permitan afrontar con menor sufrimiento el suceso; el cual implica, una etapa posterior de adaptación, a la cual se le denomina duelo. El objetivo del presente trabajo es identificar la relación entre el tipo de duelo y las estrategias de afrontamiento utilizadas en familias que pierden a uno de sus miembros; a partir de la revisión aplicada de trabajos relevantes existentes en la literatura científica. De un total de 559 referencias bibliográficas, se seleccionaron siete estudios que cumplían con los criterios de selección definidos. Los resultados de la revisión evidencian la relación entre las estrategias de afrontamiento centradas en las emociones y el duelo complicado; y entre las estrategias de afrontamiento centradas en el problema y el duelo normal.Death is a taboo subject because of the pain it causes. This has generated that it is not approached with the necessary depth; and that, when a loved one is lost, people feel faced with a new situation without strategies that allow them to face the event with less suffering; which implies a later stage of adaptation, which is called mourning. The objective of this work is to identify the relationship between type of grief and coping strategies used in families that lose one of their members; from the applied review of relevant existing works in the scientific literature. From a total of 559 bibliographic references, seven studies were selected that met the defined selection criteria. The review results show the relationship between coping strategies focused on emotions and complicated grief; and between problem-focused coping strategies and normal grief

Rana alergijska reakcija na metilprednizolon sa tolerancijom drugih kortikosteroida

Introduction. In spite of the wide usage of corticosteroids for the treatment of a plethora of diseases, sometimes they can induce immediate hypersensitivity reactions, which are however uncommon. Case Outline. We report a case of immediate allergic reaction induced by intravenous methylprednisolone given before operation for surgical repair of an arm contracture as a sequel of burns, which the child had tolerated a month before. Six weeks later the patient repeated the anaphylactic reaction during skin testing to methylprednisolone. In addition, basophile activation test with methylprednisolone (BAT) was positive. Conclusion. This case report describes a patient who experienced intraoperative anaphylaxis and anaphylactic reaction induced by skin testing. This is the first report on induction of both anaphylactic reactions by methylprednisolone in the same child. Clinical findings, positive BAT and positive skin tests with methylprednisolone imply that the child developed type-I hypersensitivity. The lack of cross-reactivity with other corticosteroids emphasizes that the reactions were caused by the steroid molecule.Uvod. Uprkos širokoj primeni kortikosteroida u lečenju od različitih bolesti, oni ponekad mogu izazvati ranu alergijsku reakciju. Prikaz bolesnika. Kod dvanaestogodišnjeg dečaka došlo je do rane alergijske reakcije izazvane intravenskom primenom metilprednizolona neposredno pre hirurške intervencije, tačnije, korekcije kontrakture šake koja se javila kao komplikacija opekotine. Mesec dana pre pojave alergijske reakcije dete je primalo metilprednizolon i dobro ga podnosilo. Šest nedelja posle operacije ponovo se javila anafilaktička reakcija tokom kožnog testiranja metilprednizolonom. Primenjen je i test aktivacije bazofila (BAT) ovim lekom, čiji je nalaz bio pozitivan. Zaključak. Ovo je prvi prikaz dve vrste anafilaktičke reakcije izazvane metilprednizolonom kod iste osobe. Klinička slika, pozitivni nalaz BAT i pozitivne kožne probe na metilprednizolon pokazuju da se kod deteta razvio prvi tip hipersenzitivne reakcije. Nedostatak unakrsne reaktivnosti s ostalim kortikosteroidima ukazuje na to da je alergijska reakcija izazvana steroidnim molekulom

Clinical and laboratory differences between Epstein–Barr and cytomegalovirus infectious mononucleosis in children

© 2016, Serbia Medical Society. All rights reserved. Introduction Infective mononucleosis is most commonly caused by Epstein–Barr virus (EBV), and in smaller percentage by cytomegalovirus (CMV). Objective The aim of this paper was to determine the clinical and laboratory differences between EBV and CMV infectious mononucleosis in children. Methods Cohort retrospective analytical research was conducted. We used data from medical history in six years period and monitored anamnestic data, frequency of inspection and palpation obtained data during physical examination, several laboratory tests, abdomen ultrasonography examination finding and emergence of disease complications. Statistical processing of data has been performed using SPSS 20. Results Total number of examined children was 137, out of which 85.4% were with EBV and 14.6% with CMV infection. Affected children were most commonly younger than eight years. Boys were affected more often. There was no difference in frequency of high temperature, sore throat, bad breath, and respiratory symptomatology between examined children. Differences were discovered in frequency of stomachaches, eyelid swelling, skin rash and fatigue. Differences were not proven in the frequency of angina, lymphadenopathy and splenohepatomegaly between the groups. Values of transaminases and lactic dehydrogenases significantly decreased after seven days of hospitalization in both groups. In children with EBV, values of transaminases declined faster than in children with CMV. Anemia and bacterial superinfection of pharynx were most common disease complications. Thrombocytopenia was more common in children with CMV infection. Average duration of hospitalization was 6.7 days. Conclusion In children with CMV abdominal pain, eyelid swelling, skin rash, fatigue and thrombocytopenia were more common. In children with EBV values of transaminases declined significantly faster

Numerical analysis of local and global buckling of a stiffened beam-column

Fenomen linearnog izvijanja je očito vrlo bitan za stabilnosti tlačenih nosača. Kritična sila izvijanja predstavlja važnu karakteristiku za projektiranje čeličnih konstrukcija. Osim toga, postojanje ukrućenja na konstrukcijskim elementima ploče ima vitalnu ulogu u cilju povećanja kritične sile izvijanja. Međutim, ova ukrućenja izazvaju preraspodjelu načina izvijanja u smislu lokalnog i globalnog izvijanja. U ovom radu uvedena su poprečna i uzdužna ukrućenja stvarne gredne konstrukcije sa zadatkom da maksimalno povećaju kritične sile izvijanja. Funkcija cilja je pronaći optimalnu geometrijsku karakteristiku ukrućenja. Na osnovu metode konačnih elemenata, numerički model je napravljen uporabom Abakus programa za utvrđivanje kritične sile izvijanja. Rezultati su pokazali da poprečna ukrućenja i njhov položaj imaju znatan utjecaj na lokalno izvijanje, dok uzdužna ukrućenja imaju mali utjecaj na lokalno i globalno izvijanje.The linear buckling phenomenon is obviously very important for stability of compressed supports. The determination of buckling resistance is an important characteristic of the design of steel structure. Besides, the presence of stiffeners in structural plate elements has a vital role in order to increase critical buckling load capacity. However, these stiffeners cause a redistribution in buckling behaviour in terms of local and global buckling. In this paper the transverse and longitudinal stiffeners were employed on a real beam-column structure to maximize the critical buckling loads. The objective is to find the optimum geometry of stiffeners. Based on the finite element method, a numerical model is made using the Abaqus program in order to observe the critical buckling capacity. The results showed that the local critical buckling has been significantly affected by stiffener\u27s position in the case of transverse stiffeners, but little effect is observed on the critical local and global buckling in the case of longitudinal stiffeners