73 research outputs found
Current usage of Component based Principles for Developing Web Applications with Frameworks: A Literature Review
Component based software development has become a very popular paradigm in many software engineering branches. In the early phase of Web 2.0 appearance, it was also popular for web application development. From the analyzed papers, between this period and today, use of component based techniques for web application development was somewhat slowed down, however, the recent development indicates a comeback. Most of all it is apparent with W3Cās component web working group. In this article we want to investigate the current state of web application development with component approach. Most of all we are interested in which way components are used, which web development frameworks are being used, for which domains is component based web development most popular and successful, etc. How many current web development frameworks explicitly refer to component-based approach? To answer this question, we performed a literature review
NumeriÄko optimiranje krutosti konstrukcije
U radu je izvrÅ”ena numeriÄka analiza krutosti konstrukcije robotiziranog sustava koji
se koristi u podruÄju neurokirurgije. Dio konstrukcije koji se proraÄunava je luÄni nosaÄ na
koji dolazi alat koji se koristi prilikom operacije. PredviÄeno je da nosaÄ bude izraÄen je
aluminija.
Cilj proraÄuna je odrediti kako Äe se konstrukcija ponaÅ”ati pod zadanim optereÄenjem i
koliki Äe tada biti maksimalni pomaci. Za to je najprije potrebno odrediti koji su konaÄni
elementi optimalni za analizu zadane konstrukcije.
Prije numeriÄke simulacije ponaÅ”anja predložene konstrukcije nosaÄa, napravljena je
verifikacija na dva modela. Prva verifikacija je provedena na luÄnom nosaÄu oblika Äetvrtine
kružnice punog pravokutnog popreÄnog presjeka, uklijeÅ”tenom na jednom kraju i
optereÄenom silom na drugom kraju. Druga verifikacija je provedena na luÄnom polukružnom
nosaÄu kutijastog profila, uklijeÅ”tenom na oba kraja i optereÄenog silom u sredini. Isti
proraÄuni su provedeni i u raÄunalnom programu Abaqus te je provedena usporedba
dobivenih rezultata. Za verifikaciju u Abaqusu su koriÅ”teni heksaedarski i tetraedarski konaÄni
elementi prvog i drugog reda.
Nakon verifikacije prikazana je numeriÄka analiza pomaka u realnom modelu
primjenom metode konaÄnih elemenata u raÄunalnom programu Abaqus. Konstrukcija je
optereÄena kontinuiranim optereÄenjem koje djeluje na povrÅ”inu na mjestu gdje dolazi
prihvatni mehanizam alata i uklijeÅ”tena na obje strane. NumeriÄka simulacija je provedena
koriŔtenjem heksaedarskih i tetraedarskih elemenata drugog reda. Pretpostavlja se da je jedino
optereÄenje koje djeluje kontinuirano optereÄenje na toj povrÅ”ini. Primarni cilj je analiza
pomaka, jer je analizom naprezanja utvrÄeno da se u nosaÄu dogaÄaju samo elastiÄne
deformacije puno manje od granice teÄenja materijala, pa daljnja analiza naprezanja nije
potrebna.
Na kraju su usporeÄeni pomaci za konstrukciju izraÄenu od razliÄitih materijala da bi
se odredilo koji od materijala je najbolji za izradu konstrukcije. Usporedbom je utvrÄeno da je
za izradu konstrukcije najpogodniji aluminij
NumeriÄka analiza debelostjenih cijevi kod naglog poveÄanja tlaka
Debelostjene cijevi imaju Å”iroku primjenu u strojarstvu, izmeÄu ostalog i u ispitivanjima eksploziva. Prilikom eksplozije, tlak u cijevi odmah naraste na svoju maksimalnu vrijednost i nakon toga u odreÄenom vremenu padne na nultu vrijednost. Zbog nagle promjene tlaka, koja ovisi o vremenu, statiÄka analiza ne može dobro opisati ponaÅ”anje cijevi te je potrebno napraviti dinamiÄku analizu.
Najprije je napravljena verifikacija na jednostavnijem primjeru na kojem se može odrediti analitiÄko rjeÅ”enje i to rjeÅ”enje se usporeÄuje s numeriÄkim. Za verifikacijski model je odabrana greda na dva oslonca na koju u sredini s visine h pada uteg mase m. Proveden je analitiÄki proraÄun kojim je dobiven maksimalni statiÄki i dinamiÄki progib grede. Te su vrijednosti usporeÄene s numeriÄkim rezultatima. NumeriÄki proraÄun je proveden pomoÄu metode konaÄnih elemenata u raÄunalnom programu Abaqus. Greda je modelirana kao trodimenzionalno tijelo i diskretizirana heksaedarskim elementima prvog reda. Konvergencija je ispitivana na statiÄkoj analizi, da bi se uÅ”tedjelo na vremenu. Nakon toga je napravljena i dinamiÄka analiza primjenom eksplicitne i implicitne metode. Iz rezultata se moglo zakljuÄiti da obje metode za zadani primjer daju približno jednake rezultate, a njihova razlika u odnosu na analitiÄko rjeÅ”enje ovisi o pozitivnoj fazi trajanja optereÄenja.
Nakon verifikacije je napravljena analiza debelostjene cijevi ukljeÅ”tene na jednom kraju i slobodne na drugom kraju te optereÄene tlakom iznutra. Radi boljeg opisivanja geometrije, koriÅ”ten je cilindriÄni koordinatni sustav. Najprije su se analitiÄkim proraÄunom izraÄunali radijalni pomaci, ekvivalentna, radijalna, cirkularna i aksijalna naprezanja pri statiÄkom optereÄenju. Te veliÄine se raÄunaju na gornjem rubu cijevi, gdje rubni uvjeti ne utjeÄu na konaÄne rezultate pa se one mogu puno lakÅ”e odrediti nego u ostatku cijevi. Ista je analiza nakon toga provedena numeriÄki, primjenom metode konaÄnih elemenata u raÄunalnom programu Abaqus. Cijev se diskretizirala 3D heksaedarskim elementima prvog reda. Da bi se uÅ”tedjelo na vremenu, konvergencija je napravljena na statiÄkoj analizi. Osim po visini cijevi, mijenjao se i broj elemenata po debljini cijevi. Rezultati statiÄke analize su usporeÄeni s analitiÄkim rezultatima i dobiveni rezultati se ne razlikuju previÅ”e u odnosu na analitiÄke rezultate.
Nakon toga je napravljena i dinamiÄka analiza na mreži konaÄnih elemenata kod koje je iskonvergiralo rjeÅ”enje statiÄke analize. DinamiÄka analiza je napravljena primjenom eksplicitne i implicitne metode. Rezultati dobiveni eksplicitnom i implicitnom metodom se razlikuju viÅ”e nego je to bio sluÄaj kod grede. Iz rezultata je uoÄeno da dinamiÄki faktor kod eksplicitne metode iznosi dva i pol, a kod implicitne neÅ”to manje od dva. Maksimalno ekvivalentno naprezanje je veÄe od granice teÄenja materijala pa se zakljuÄuje da su pojedini dijelovi cijevi uÅ”li u plastiÄno podruÄje, zbog Äega je potrebno poveÄati debljinu cijevi ili promijeniti materijal cijevi ili smanjiti koliÄinu eksploziva, Äime se dobije manji tlak kojim je cijev optereÄena.
Kako je u verifikaciji pokazano da se bolje poklapanje s analitiÄkim rjeÅ”enjem dobije pri poveÄanju vremena optereÄenja, napravljena je dinamiÄka analiza te cijevi kod vremena trajanja optereÄenja od jedne sekunde. Ti su se rezultati usporedili s rezultatima dobivenima kod kraÄeg vremena trajanja.
Na kraju je napravljena analiza cijevi od jednakog materijala i pri jednakom optereÄenju, ali s veÄom debljinom stijenke i ta je cijev zadovoljila uvjet da su naprezanja niža od granice teÄenja
INFLUENCE OF DIMENSIONS OF TEST SPECIMENS ON THE MACHANICAL PROPERTIES OF MATERIAL
U teorijskom dijelu ovog zavrÅ”nog rada bit Äe opisana mehaniÄka svojstva materijala i metode ispitivanja tih svojstava, dok Äe u drugom dijelu biti opisan pokus i analiza dobivenih rezultata. Kod opisivanja mehaniÄkih svojstava, pažnja Äe biti usmjerena na ispitivanje statiÄkim vlaÄnim pokusom i ispitivanje tvrdoÄe koje Äe se detaljnije analizirati i dodatno objasniti, dok Äe ostale metode biti u kratko opisane. TakoÄer, bit Äe i objaÅ”njeno poboljÅ”avanje materijala jer su epruvete poboljÅ”avane. U eksperimentalnom dijelu, pogled je na materijal koji je koriÅ”ten za izradu epruveta te dodatan opis njegovih karakteristika. Zatim slijedi opisivanje opreme koju smo koristili pri ovome pokusu, plan pokusa, te naposljetku, rezultati pokusa, njegova analiza i zakljuÄak.In the theoretical part of this thesis, mechanical properties of materials and the methods of assesing those properties will be described. In the second segment the experiment will be described and an analysis of the results will be given. When describing the mechanical properties, the focus will be put on the using the static tensile test and the hardness testing which will be analyzed in detail and additionally explained, while the other methods will be described in brief. Also, since the vials were enhanced, we will describe material improvements. In the experimental segment, we will focus on the material used for making the epruvetes and will add a description of its properties. Next, we will describe the equipment used in this experiment, the experimental protocol, and, the results, their analysis and conclusion
Two Years of Gamification of the Course - Lessons Learned
Gamification has been applied in different levels of education (elementary, high school, university) for roughly last 5 years. Many researches deal with how to improve education process by usage of game mechanics and other game based elements in their teaching activities. One of the important part of research in the area of education is what part of the course is involved in the research. If it covers some smaller part of the course, for example, one topic that correspondents to a chapter from common course literature and the gamification is limited to few weeks then we could not get the full picture of its real good and bad sides. Some students got excited when teacher use new methods and lost interest after few weeks. However, the course lasts much longer then few weeks and it is much harder to apply gamification for the full course content and to keep studentsā interest during the whole education process like semester with 15 weeks. The paper presents our experience with gamified course in two consecutive academic years. We gamified whole course content and learning activities. First year we had half students in gamified version of the course as an experimental group and the other half of students as a control group. The experimental group based on their groupings had all gamified experiences that standard Moodle distribution and chosen plugins provide. The control group was not formally and fully included in all aspects of gamified version of the course but the teachers manually record all their earnings (badges, experience points etc.) even the students were not aware of it. We made some comparisons based on those groups and their achievements, usage of the Moodle etc. We analysed the studentsā survey they fill at the end of the course, also our remarks we made during the course. Those were inputs to smaller adjustments for next year (for example we provided more information about the best award). In the second year, the whole course student population was using gamified version of the course. Again, we analysed the studentsā survey they fill at the end of the course. We compared those two years in many elements. Some of results were expected but some were not. Finally, we compare our experience with other researches in the area of gamification
News Cohesiveness: an Indicator of Systemic Risk in Financial Markets
Motivated by recent financial crises significant research efforts have been
put into studying contagion effects and herding behaviour in financial markets.
Much less has been said about influence of financial news on financial markets.
We propose a novel measure of collective behaviour in financial news on the
Web, News Cohesiveness Index (NCI), and show that it can be used as a systemic
risk indicator. We evaluate the NCI on financial documents from large Web news
sources on a daily basis from October 2011 to July 2013 and analyse the
interplay between financial markets and financially related news. We
hypothesized that strong cohesion in financial news reflects movements in the
financial markets. Cohesiveness is more general and robust measure of systemic
risk expressed in news, than measures based on simple occurrences of specific
terms. Our results indicate that cohesiveness in the financial news is highly
correlated with and driven by volatility on the financial markets
Process Model Improvement for Source Code Plagiarism Detection in Student Programming Assignments
In programming courses there are various ways in which students attempt to cheat. The most commonly used method is copying source code from other students and making minimal changes in it, like renaming variable names. Several tools like Sherlock, JPlag and Moss have been devised to detect source code plagiarism. However, for larger student assignments and projects that involve a lot of source code files these tools are not so effective. Also, issues may occur when source code is given to students in class so they can copy it. In such cases these tools do not provide satisfying results and reports. In this study, we present an improved process model for plagiarism detection when multiple student files exist and allowed source code is present. In the research in this paper we use the Sherlock detection tool, although the presented process model can be combined with any plagiarism detection engine. The proposed model is tested on assignments in three courses in two subsequent academic years
Common Metamodel of Component Diagram and Feature Diagram in Generative Programming
Component-based software engineering and generative programming are common approaches in software engineering. Each approach has some benefits and domain of usage. Component-based development is used to build autonomous components that can be further combined in different ways, while generative programming is more suitable when building systems that have different variants. Before a variable component based system can be build, it needs to be modeled. In this article, a new common metamodel that aims to enable modeling a system which combines both component-based development and generative programming is introduced. The introduced metamodel proposed in this paper combines the component diagram that is used to model systems in component-based development and the feature diagram that is employed in modeling systems in generative programming. The combined metamodel enables modeling of variable systems using components
Integrity constraints in graph databases - implementation challenges
Graph databases are becoming more and more popular as they represent a good alternative to relational databases for some problem scenarios. Searching a graph is sometimes very convenient, unlike writing complex SQL queries that require a table to be joined to itself several times. However, graph databases do not support all the constraints that are familiar and used in relational databases. In this paper, we discuss integrity constraints in graph databases and technical implementation issues that prevent these constraints from being specified
Integrity constraints in graph databases - implementation challenges
Graph databases are becoming more and more popular as they represent a good alternative to relational databases for some problem scenarios. Searching a graph is sometimes very convenient, unlike writing complex SQL queries that require a table to be joined to itself several times. However, graph databases do not support all the constraints that are familiar and used in relational databases. In this paper, we discuss integrity constraints in graph databases and technical implementation issues that prevent these constraints from being specified
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