Dinamička analiza rastojnika-prigušivača

U radu je predočena teorijska baza pojave eolskih vibracija snopa vodiča dalekovoda te princip njihovog prigušenja primjenom rastojnika-prigušivača. Analiziran je jedan tip rastojnika-prigušivača te su dobivene elastične i inercijske karakteristike pojedinih dijelova i čitavog sklopa. Korištenjem programa za konačne elemente kreiran je dinamički model rastojnika kojemu su pridružene dobivene elastične i inercijske karakteristike, zadana ograničenja u vidu nekoliko krutih tijela radi pojednostavljenja modela te su definirane kontaktna ograničenja u zglobovima. Zadani su rubni uvjeti na temelju ograničavanja sustava prilikom laboratorijskih ispitivanja. Model je prevučen mrežom konačnih elemenata te je provedena frekvencijska analiza pa je dobiveno prvih deset glavnih formi vibriranja i slobodnih vibracija. U numerički program za analizu eolskih vibracija su zatim uneseni dobiveni podaci te je dobiveno ponašanje čitavog sustava s dva vodiča i četiri rastojnika

Solving mathematical problems in real context: Qualitative and quantitative analysis of achievement

Osnovno istraživačko pitanje kojim se bavi ovaj rad je pitanje identifikovanja osnovnih prepreka na koje učenici nailaze pri rešavanju zadataka iz matematike, kako bi se definisali tipični koraci u ovladavanju matematičkim veštinama potrebnim za rešavanje primenjenih zadataka. U konceptualnom pogledu, rad je uklopljen u savremena određenja matematičke pismenosti kao kompetencije koja omogućava pojedincu da razume svet u kojem živi i da je osposobljen da donosi zasnovane odluke (npr. OECD/PISA). Istraživanje je realizovano u dve faze. Kvalitativnim istraživanjem, u uslovima individualnog ili interaktivnog rada na zadatku, nastojali smo da utvrdimo na koje načine učenici greše i na koje poteškoće nailaze pri rešavanju zadataka smeštenih u realan kontekst, kao i da utvrdimo koje su od tih grešaka i poteškoća tipične. Analizom sadržaja verbalnih iskaza učenika tokom rešavanja zadataka izdvojeni su problemi koji čine strategije rešavanja neefikasnim. Kvantitativnim istraživanjem proveravali smo u kojoj meri su greške i poteškoće ustanovljene u prethodnoj fazi tipične, što može biti jasan dijagnostički znak koji ukazuje na sistemski nedostatak u nastavi matematike i instrumentima za procenu postignuća učenika. Uzorak je činilo 379 učenika prvog razreda beogradskih srednjih škola. Rezultati pokazuju da se uklanjanjem suvišnog podatka iz matematičkog zadatka statistički značajno podiže uspešnost u rešavanju, što ukazuje na to da učenici uspešno rešavaju one zadatke u kojima su selektovani podaci koji su potrebni za predviđene matematičke procedure. Preporuka je da se nastavnom praksom podržava i razvija veština selekcije podataka - da se iz velikog broja raspoloživih podataka izdvoje samo oni koji su neophodni u procesu rešavanja zadataka.The basic research issue that this paper is dealing with relates to the question of identifying major obstacles the students meet when solving mathematical tasks, in order to define typical steps in acquiring mathematical skills necessary for solving applied tasks. Concetualization wise, our work is in accordance with contemporary definitions of mathematical literacy, seen as a competence which enables the individual to understand the world in which they live and to reach sound decisions (e.g. OECD, PISA). The research was conducted in two phases. By a qualitative research, in the conditions of individual and interactive work on the task, we tried to establish the ways in which the students make mistakes and the difficulties they encounter when solving the tasks situated in real context, as well as to determine which of these mistakes and difficulties are typical. By analyzing the students' verbal comments during the performance we singled out the problems which make the selected strategies inefficient. Using quantitative analysis we tried to establish which mistakes and difficulties, determined in the previous phase, are typical and might be taken as a clear diagnostic signal indicating a systemic lack in teaching mathematics and instruments for measuring students' achievements. The sample comprised 379 first-grade students from secondary schools in Belgrade. The results show that after removal of redundant data from a mathematical task successfulness in solving it increases statistically significantly, which indicates that students successfully solve those tasks which contain only selected data, necessary for the application of adequate mathematical procedures. Our suggestion is that teaching practice should support and develop the skill of data selection, i.e. from numerous data to select only those which are necessary in the process of task solving

STANKO KLISKA (1896 – 1969): ARCHITECT OF THE HOSPITAL AT SUŠAK IN RIJEKA

Aim: This paper is to show that the hospital in Su{ak, Rijeka has been built on modern principles of hospital building during, even though it is seventy-odd years old. Material and methods: The paper relies on published texts and illustrations about the hospital in Su{ak and about its architect Stanko Kliska. Results: Designing the hospital, architect Stanko Kliska focused on the needs of the patient He has built it using simple materials, seeking to meet all requirements imposed by function and the surroundings. The hospital in Su{ak has a three-storey building with a cellar and a roof terrace. The hospital is about one hundred metres long and is divided in two aisles. Its front faces south-west. Patient rooms look to the south. Other accessory and operating rooms look to the north. The hospital has three wide stairways; one runs in the middle and other on the sides of the building central hall. Conclusion: There is no doubt that the hospital in Su{ak, Rijeka is a product of modern architectural design. Since 1934, with its impressive vista, it has been regarded as a rehabilation center rather than any of the contemporary hospitals of the turn of the 21st century

Intestinal helminth parasites of the grey wolf (Canis lupus L.) in Serbia

The grey wolf (Canis lupus L.) is the most widespread large carnivore in Europe with large populations in the Eastern part of Europe and the Balkan Peninsula. In this study, a total of 102 wolves were examined for intestinal helminth parasites. The carcasses were collected within the Serbian part of the wolf’s range during the period 2009–2014. Nine helminth species were found: one nematode, Toxocara canis (3.9%), one trematode, Alaria alata (1.0%), and seven cestodes, Taenia pisiformis (1.0%), T. hydatigena (9.8%), T. polyacantha (2.9%), T. taeniaeformis (2.0%), T. (syn. Multiceps) multiceps (3.9%), T. serialis (1.0%) and Mesocestoides litteratus (1.0%). Taenia (syn. Hydatigera) taeniaeformis has been registered for the first time in a wolf from Europe. An overall moderate prevalence (16.7%) of infected wolves was recorded. There was no statistically significant difference in prevalence between sexes. Of the years studied, the highest prevalence was found in 2014 (57.1%). The maximum number of helminth species per host specimen was four

The role of drug-coated balloons in endovascular interventions

The drug coated balloons are evolution in treatment of clotted blood vessels. The era of interventional endovascular medicine began with balloon dilatation, further progress represented bare metal stents and after that drug eluting stents. In the last few years, interventional cardiology recognized the need for further evolution in treating clotted arteries.1 The concept of DCB is distribution of cytostatic drug (most commonly Paclitaxel) locally through a balloon, which is blocking uncontrolled hyperplasia of the endothelium, most common cause of restenotic lesions. This is done to prevent implanting a permanent metal, and to shorten the usage of antiaggregation therapy. The main components of DCB are balloon drug and drug carrier. Drug carrier is very important in technical concept of successfully designed DCB. DCB is usually used as conventional balloon except avoiding hand contact with the surface of the balloon is necessary because it can damage the drug. The targeted drug delivery needs to be quick because the drug releases its substance at the moment when its entries in blood flow. Ideal drug delivery for coronary intervention to the vessel lesion is 60 seconds (time from entering in blood flow till finishing inflating the balloon). Indications for DCB usage in coronary interventions are in stent restenosis, coronary narrow lesions. DCB has wide usage in interventions of peripheral arteries. It’s more common usage of DCB in “de novo” coronary artery lesions after adequate preparation of the lesion with various methods (scoring balloons, cutting balloons, NC balloons). In now days DCB are unavoidable cardiac catheterization laboratory tool and whose usage is on the rise. For further expansion of indications and growing number of interventions additional study evaluations needs to be done

DYNAMIC BEHAVIOR OF TWO ELASTICALLY CONNECTED NANOBEAMS UNDER A WHITE NOISE PROCESS

This paper investigates the almost-sure and moment stability of a double nanobeam system under stochastic compressive axial loading. By means of the Lyapunov exponent and the moment Lyapunov exponent method the stochastic stability of the nano system is analyzed for different system parameters under an axial load modeled as a wideband white noise process. The method of regular perturbation is used to determine the explicit asymptotic expressions for these exponents in the presence of small intensity noises

Lumbricidae as transitory hosts in Metastrongylus infection in swine

Metastrongylidosis or lungworm disease in swine is a disease caused by several types of nematodes of the genus Metastrongylus. Metastrongylidae are biohelminths whose causes use transitory hosts for their development and maintaining their biological cycle, and in this case they are numerous species of Lumbricidae (earthworms). Depending on the geographic environment, numerous representatives of Lumbricidae persist as transitory hosts. In our environment, these are dominant earthworm species of the genus Eisenia spp, Dandreobena spp, Allopbophora spp, Lubricus spp, Octoiasium spp, Bimastus spp, and rarely those from the genus Heledrillus spp. Swine are infected perorally with Metastrongylidae when they ingest infected earthworms

Preliminary identification of residential environment assessment indicators for sustainable modelling of urban areas

Increasing population density in urban areas is closely followed by a number of negative aspects, which can significantly affect the quality of housing, as well as its sustainability. The aim of this paper is to identify the most important indicators influencing the quality of residential environment, and to give information for sustainable decision-making and modelling of urban areas. To know the significance of certain indicators presents a very important element in planning and decision making process. This gives the decision-maker an insight into elements to which a proper attention should be given during urban area management. Using a web-based questionnaire, as well as personal questioning, the data for three cities: Brno (Czech Republic), Rijeka (Croatia), and Podgorica (Montenegro) were collected, analyzed, and compared. Results of the performed statistical analysis show that differences among the examined cities exist, and that among indicators, several can be considered very similar, while others differ significantly. The indicators were categorized in three groups (key, important, and marginal) according to their given importance. The conducted research gives a preliminary insight into the population\u27s perception of the importance of indicators, which is established as a necessary element of the sustainable decision-making process in urban area management

Vitlo za vuču parajedrilice

širenjem padobranskog jedrenja u nizinske krajeve pojavila se potreba za mogućnošću lansiranja parajedrilica na terenima s velikom visinskom razlikom. Kao najraširenije rješenje pokazala su se vitla za vuču, bilo statička ili pokretna. U ograničenim prostorima bez dugih ravnih zaletnih terena statička vitla imaju prednost. Dosadašnja rješenja statičkih vitla su uglavnom kućne radinosti uz korištenje iskustvenih podataka leta parajedrilica. U ovom radu dana je fizikalna analiza promjenjive sile koja djeluju na uređaj, njen odnos s također promjenjivom brzinom vuče te su dane rezultirajuće potrebe za snagom. \Na temelju te analize pristupilo se metodičkoj razradi statičkog uređaja za vuču parajedrilica u kojoj je prikazan cijeli proces konstruiranja te cjelokupni tehnički proračun i potrebna tehnička dokumentacija