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Population census is often a popular topic in everyday conversations. After extensive research, a conclusion was made that currently no services exist that offer a convenient, easily interpretable information about the census. Our solution for this problem is CroStats – a simple web interface for population census data visualization intended for general public. The central feature of the CroStats is its intuitive and simple graphical display. It analyzes the most important categories of the population census by county such as population, age, birth rate and mortality. All this information is displayed on an interactive map of the Republic of Croatia. Extra features offered are graphs of changes by year and interesting historical and demographic facts about counties that the broader audience may have interest in.

The Sava River Basin, as the largest river basin in Croatia, is of great importance for the water resources management and hydrological research in Croatia. The general intensification of extreme climatic conditions increases the number of flood events worldwide, which may indirectly affect the morphodynamical behavior in the riverbed. Valuable information on the flood-generation mechanisms may be contained in the flood hydrograph shapes, which can be expressed as continuous functions using a functional data approach [1]. In this research, we performed a preliminary analysis of annual flood events at the gauging station (GS) Zagreb by applying a clustering mechanism based on functional data to identify a set of representative hydrograph shapes that contain valuable information for future research on scour in the vicinity of bridges. Flood events that capture river’s flood regime can be represented as classical multivariate data or functional data, to be subsequently classified by applying a clustering algorithm. The functional analysis can provide a more objective and reproducible definition of the actual hydrological phenomena than the classical multidimensional analysis because it avoids the subjective selection of a set of hydrograph characteristics. Functional data analysis starts by considering the discrete data observations as part of a finite- dimensional space spanned by a set of basis functions and coefficients that define their linear combination. In addition, the choice of the appropriate order of polynomial segments and the number and placement of the knots are determined to represent the main characteristics of the hydrograph shapes. Finally, the resulting set of coefficients is used as an input for clustering. Since the hydrograph shape clusters can only be validated by their interpretability and usefulness, their evaluation was performed graphically [1, 2]. The input data for the analysis was a historical time series of daily discharge data from the Zagreb gauging station in the Sava River basin for the reference period 1960-2019, provided by the Croatian Meteorological and Hydrological Service. The time series consists of 21878 observations (60 years of data). The annual maxima method was applied to the time series to extract independent flood events corresponding to the maximum annual peak discharge values. For each event the flood volume and duration were determined over a fixed window corresponding to the longest duration of the rising and falling limb of all considered flood events, resulting in 16 days before and 38 days after the peak discharge (55 daily observations). The baseflow was separated from the direct flow using the R package “lfstat”, with the direct flow component normalized by dividing the ordinate of each hydrograph with the total volume of the flood event. Finally, a functional data analysis was performed by spanning B-spline functions of differing ranks onto the resulting direct flow data observations followed by implementing a k- means clustering algorithm to separate flood events into different clusters. For each cluster, a median was determined to represent three distinct types of hydrograph shapes. For this analysis the B-spline rank of 25 and the K value of 3 were ultimately chosen. This approach resulted in identifying three distinct types of flood events: (1) slow events described as both elongated rising and falling limbs, (2) intermediate events with steep rising limbs and moderately steep falling limb, and (3) fast events with steep rising and falling limbs of the hydrographs. This preliminary analysis was conducted in order to exploit the valuable process information contained in flood hydrograph shapes, which can be of great value for the future research within the R3PEAT project (“Remote Real- time Riprap Protection Erosion Assessment on large rivers”, UIP-2019-04-4046) supported by Croatian Science Foundation, that explores influences on the riverbed erosion around structure of bridges crossing large rivers in Croatia [3].

Sustavi za društveno umrežavanje (Facebook, Twitter, Instagram i slični) široko su rasprostranjena digitalna platforma za komunikaciju i interakciju milijardi ljudi. Podatci o interakciji ljudi pohranjuju se na strukturiran – računalno čitljiv način, što (uz odgovarajuću suglasnost ljudi o čijim se podatcima radi) omogućuje njihovu obradu, analizu i izlučivanje različitih zaključaka. Dostupnost podataka o interakciji temelj je svih istraživanja društvenih mreža – kako onih sociologijskih i psihologijskih, tako i onih iz područja računalne znanosti. U ovome doktorskome radu provedena su društvena istraživanja kroz koja su (uz suglasnost ispitanika) prikupljeni podatci o interakciji korisnika na sustavu za društveno umrežavanje Facebook te usporedno korisničke procjene njihova odnosa s ljudima s kojima na Facebooku interaktiraju. Time je oformljen referentni podatkovni skup za istraživanja društvenih mreža. Oformljen referentni podatkovni skup u radu je detaljno analiziran. Korištenjem referentnog podatkovnog skupa, osmišljen je, implementiran, ugođen i verificiran model za računanje društvene udaljenosti na temelju podataka o interakciji ljudi na Facebooku. Za razliku od prethodnih istraživanja koja su intenzitet odnosa među ljudima prikazivala primjenom koncepta težine ili snage veze, društvena udaljenost inovativan je način iskazivanja intenziteta odnosa među ljudima kroz primjenu koncepta udaljenosti. Osnovna značajka koncepta udaljenosti jest da se veći intenzitet prikazuje manjim brojem, što je vrlo pogodno za daljnje primjene kao što su određivanje vremena propagacije informacije ili određivanje približne geografske lokacije korisnika. U radu je definiran model obogaćenoga društvenoga grafa. Obogaćeni društveni graf formalni je prikaz društvene mreže, tj. odnosa među ljudima. Obogaćenim društvenim grafom moguće je zapisati različite vrste i intenzitete odnosa među ljudima. Intenzitet odnosa među ljudima bilježi se kao njihova društvena udaljenost, a ona se računa na temelju modela koji se u ovom radu uvode. Social networking sites (Facebook, Twitter, Instagram, etc.) are widely used digital platforms for communication and interaction between billions of people. Data about users’ interaction is stored in a structured and computer readable format, which makes possible (with the appropriate consent of the people whose data are) to process it, analyze and come up with various conclusions. The availability of data about people’s interaction is the foundation for all social networks' researches – both sociological and psychological, as well as those in the field of computer science. In this doctoral thesis a number of social surveys were conducted (with the appropriate consent of the examinees) and reference datasets for social network researches were collected. Datasets contain data about users’ interaction on the social networking site Facebook and users’ estimation of the relationship intensities with their Facebook friends. Collected reference datasets are analyzed in detail. By using a reference dataset, a model for computing social distance based on people's interaction data on Facebook is designed, implemented, fine-tuned and verified. Unlike previous researches showing the intensity of interpersonal relations by applying the concept of weight or tie strength, social distance is an innovative way of expressing the intensity of relationship between people through the concept of distance. The main feature of the concept of distance is that the higher intensity is shown by the smaller number. It is very suitable for further applications such as determining the propagation information time or determining the user’s approximate geographic location. Thesis defines model of enriched social graph. Enriched social graph is formal representation of social network, i.e. formal representation of relations between people. Enriched social graph can record different types of interpersonal relations and their intensities. Intensity of interpersonal relations is shown as their social distance, which is calculated by using model previously introduced in this thesis.

Predavanje se bavi izgradnjom i analizom društvenih grafova. Prezentirani su primjeri iz telekomunikacijske i financijske industrije te primjer izgradnje društvenog grafa na temelju interakcije korisnika na društvenoj mreži Facebook.

Facebook, the popular online social network, is used on daily basis by over 1 billion people each day. Its users use it for message exchange, sharing photos, publishing statuses etc. Recent research shows that a possibility exists of determining the connection level (or strength of their friendship, tie strength) between users based on analyzing their interaction on Facebook. The aim of this paper is to explore, as a proof of concept, the possibility of using a model for calculating strength of friendship to compare and classify ego-user’s Facebook friends. A survey, which involved more than 2500 people and collected a significant amount of data, was conducted through a developed web application. Analysis of collected data revealed that the model can determine with a high level of accuracy the stronger connections of ego-user and classify ego-user’s friends into several groups according to the estimated strength of their friendship. Conducted research is the base for creating an enriched social graph – graph which shows all kinds of relations between people and their intensity. Results of this research have plenty of potential uses, one of which is specifically improvement of the education process, especially in the segment of e- learning.

Elaborat analizira SEPA-u.

Rad se bavi pohranom elektroničkog potpisa u formatu XML.

Rad se bavi analizom tehnologija e-poslovanja.

U prva dva poglavlja elaborata analiziraju se predlošci za XML-dokumente: DTD i XML Schema. Analizirane su tehnologije za obradu i validaciju XML-dokumenata spram predloška: SAX, DOM, JiBX i XSLT. U trećem poglavlju opisana je tehnologija razmjene poruka u Javi - Java Message Service (JMS). U četvrtom poglavlju objašnjeni su temeljni principi usluga weba. U petom poglavlju analizirani su načini pohrane XML-dokumenata. U šestom poglavlju razmatrana je sigurnost u elektroničkom poslovanju s naglaskom na sigurnost XML-dokumenata, tj. mogućnost njihova digitalnog potpisivanja.

Rad se bavi transformacijom e-računa između normi e-SLOG i UBL 2.1

Izvedeni su ispitani te međusobno uspoređeni modeli dubinske analize podataka za predviđanje krovne brojke i akcijskog udjela prodavaonica za zadane artikle koji će omogućiti unaprjeđenje promocijske prodaje. Pri predviđanju krovne brojke potrebno je napraviti dobre procjene na dvije razine: (1) procijeniti krovnu brojku – ukupnu potražnju za određenim artiklom na određenoj akciji na nivou cijele Hrvatske, i (2) predvidjeti najbolju distribuciju – podijeliti akcijski artikl po prodavaonicama kako bi što manje dolazilo do prekomjernih zaliha ili pak do nestašica. Analizirane su postojeće baze podataka vezane uz akcije te skladišta podataka vezana uz maloprodaju, te je napravljen konceptualni model skladišta podataka akcijskih prodaja koji bi omogućio različite analize i višedimenzionalne prikaze podataka vezanih uz akcijsku prodaju.

Social networks based on ICT (Information and Communication Technology) are nowadays one of the most popular services based on the Internet infrastructure. They are global phenomenon that greatly affects the modern way of life. Contrary to the widespread opinion, which assumes that social networks are interesting only for private users, these networks can produce added value in companies as well. The corporate social network is a system based on the web technologies that enables agile collaboration and information exchange within company. According to the method of making connections, social networks can be divided into two groups: implicit and explicit networks. While in explicit social networks a person herself defines another person to connect with, implicit networking is determined by a person’s interests and by the level of communication and collaboration with other persons. This paper addresses the question of developing implicit corporate social networks. Based on the analysed communication performed through several communication channels (i.e. e- mail, file transfer, telephone calls and instant messaging) between the employees of a multinational company, we propose an algorithm for building the social network graph. Our algorithm calculates the level of connection between employees based on the level of communication between them. We verified the proposed algorithm on our prototype test application, the FER CSN Analysis.

Elektronička razmjena računa donosi značajno smanjenje troškova. Za smanjenje troškova i poticanje korisnika na elektroničku razmjenu računa iznimno je važna automatizacija procesa razmjene e-računa. Cilj je proces razmjene računa provesti u potpunosti elektronički bez potrebe za ispisivanjem računa. Također, pošiljatelj računa treba biti u mogućnosti poslati račun primatelju samo na temelju informacije tko je primatelj, a bez da mora znati tko je informacijski posrednik primatelja. O usmjeravanju računa među informacijskim posrednicima trebaju se brinuti sami informacijski posrednici. U Hrvatskoj trenutno posluje 10-ak informacijskih posrednika koji uglavnom međusobno ne razmjenjuju račune što onemogućuje gore opisani proces. U takvoj situaciji pošiljatelj računa može slati račune samo ostalim klijentima svog informacijskog posrednika. Omogućavanje razmjene e-računa među različitim informacijskim posrednicima preduvjet je za automatizirani proces razmjene računa što će neminovno rezultirati i porastom broja elektronički razmijenjenih računa (trenutno se u Hrvatskoj elektronički razmjenjuje tek 2% računa). Bitna karika za automatizaciju tog procesa jest registar korisnika e-računa. U registru korisnika bilježit će se podatci o korisnicima zajedno s informacijom o tome tko je informacijski posrednik pojedinog korisnika što će omogućiti razmjenu i automatsko usmjeravanje računa među korisnicima različitih informacijskih posrednika. Na predavanju će biti prikazana motivacija za uvođenje registra korisnika e-računa u sklopu čega će biti i osvrt na Stručni skup o registru korisnika e-računa koji je u studenom 2012. održan na Fakultetu elektrotehnike i računarstva (FER). Također, bit će prezentirane i šire aktivnosti koje se provode na FER-u u području oblikovanja i izgradnje sustava za razmjenu elektroničkih računa s naglaskom na registar korisnika e-računa. Electronic invoice exchange brings significant cost savings. To reduce costs and encourage users to exchange invoices electronically, automation of e-invoice exchange process is extremely important. The goal is to carry out the invoice exchange process fully electronically without printing invoices. Also, an invoice sender should be able to send an invoice to the receiver based only on information who the receiver is, and without having to know who the receiver’s service provider is. Service providers should take care about e-invoice routing. Nowadays, about 10 service providers operate in Croatia and they generally do not exchange e-invoices between themselves. In this situation, an e-invoice sender can send e- invoices only to other customers of the same service provider. Enabling e-invoice exchange between different service providers is a prerequisite for automation of e-invoice exchange process, which will result in increasing rate of electronically exchanged invoices (nowadays, only 2% of invoices are electronically exchanged in Croatia). An e-invoice users registry is very important for the automation of this process. In the registry, data about users and their service providers will be stored. By using the registry, exchange and automatic e-invoice routing between different service providers will be enabled. This presentation will show a motivation for the implementation of the e-invoice users registry in Croatia. An overview of Expert conference on e-invoice users registry, held at the Faculty of Electrical Engineering and Computing in Zagreb (FER) in November 2012, will be given. Furthermore, general activities that are carried out at FER in the field of designing and implementing an e-invoice exchange system, with emphasis on the e-invoice users registry, will be presented.

Koncern AGROKOR, kao najveća privatna i jedna od najuspješnijih hrvatskih kompanija, opredijelio se prije više godina za sustavno uvođenje elektroničkog poslovanja i poslovne inteligencije. U okviru toga u suradnji s FER-om napravljeno je niz istraživanja i unaprjeđenja njegovih postojećih informacijskih sustava. Neke od obrađenih tema su preporučiteljski sustavi, upotreba aplikacija otvorenog koda, izgradnja implicitne korporacijske društvene mreže (iCSN) poduzeća mStart te njezina analiza (SNA), analiza korištenja korporacijskih usluga kao i unaprjeđenje postojećih te razvoj novih aplikacija.

Rad prikazuje aktivnosti u području elektroničkog poslovanja na Fakultetu elektrotehnike i računarstva s posebnim naglaskom na sustav za razmjenu e-računa - FER e-račun.

An e-invoice is the most widely used electronic document in the world. Although it covers only one segment of the entire supply chain, the e- invoice has a central role in the development of electronic business. In this paper, concept, development and implementation of electronic invoicing systems are presented on a case study of an e-invoice system named FER e-invoice. The system has the following characteristics that make it different from other similar systems: the FER e-invoice system is based on scalable, open and modern 4-corner architecture which is applicable in real business environment ; the system is able to transform invoices between some of the most used XML-based e-invoice standards (the system contains one of the first implementations of the CII 2.0 standard) – this feature enables both SMEs and large enterprises to use the system ; it is the first implementation of e-invoice system in accordance with the E-invoice specification issued by Croatian E-invoice Committee ; the system enables automatic generation of a payment order from an e-invoice ; as functional addition to the basic system, a data warehouse was developed to enable business analyses process ; the system was developed by using modern technologies such as web application and web services that enterprises enables reducing coasts.

U današnje vrijeme sve je važnije poslovne procese čim više automatizirati što se obavlja elektroničkim poslovanjem. Vrlo važan poslovni proces razmjena je elektroničkih računa (e- računa). Na FER-u je razvijen sustav za razmjenu elektroničkih računa FER e-račun. Sigurnost informacijskih sustava općenito pa tako i sigurnost sustava FER e-račun vrlo je važna. U ovom je članku opisano kako je u sustavu FER e- račun implementirana sigurnost. Ona je u ovom sustavu implementirana u pet osnovnih koraka: za pristup korisnika bilo kojoj od aplikacija od kojih se sustav sastoji potrebno je proći proces autentifikacije i autorizacije ; sav korisnički unos provjerava se s ciljem zaštite od unosa zlonamjernog koda ; veza između klijentskih računala i poslužitelja informacijskih posrednika provodi se korištenjem sigurnosne nadgradnje protokola HTTP, protokolom HTTPS koji koristi sigurnosni protokol SSL/TLS ; komunikacija između informacijskih posrednika odvija se korištenjem web-usluga čija je sigurnost osigurana sigurnosnim proširenjem WS-Security ; računi koji se kroz sustav razmjenjuju digitalno se potpisuju korištenjem FINA-ine pametne kartice.

An e-invoice is the most widely used electronic document in the world. Although it covers only one segment of the entire supply chain, the e- invoice has a central role in the development of electronic business. An electronic invoicing system named an FER e-invoice is built at the University of Zagreb Faculty of Electrical Engineering and Computing (FER). The FER e- invoice system contains business processes that should be monitored and analyzed. Therefore, a data warehouse, containing data extracted from e- invoice XML documents, has been developed. Multidimensional model of the data warehouse consists of two fact tables, one for the invoice heading and one for the invoice items, and of 14 dimensional tables. In this paper the developed data warehouse is presented.

Volleyball Information System (VIS) is an information system that was built to be used as a support for the conduct of volleyball competitions, as well as the support for informing the public about volleyball. The system is composed of a central database where all the data is stored and of a set of web portals through which the authorized users can enter data into the system and through which the stored data is clearly presented to the public. This paper presents the case study of Croatian Volleyball Information System. The architecture, functionality and importance of the designed system are described.

U današnje se vrijeme sve više poslovnih procesa digitalizira i automatizira. Kroz taj se proces javljaju novi sigurnosni izazovi. Potrebno je riješiti sigurnost prijenosa i pohranjivanja podataka te pronaći jednako vrijedan nadomjestak tradicionalnom vlastoručnom potpisu i pečatu. Za sigurnost prijenosa podataka komunikacijskom mreţom postoje različiti protokoli koje se mogu implementirati na različitim slojevima komunikacijske mreţe. Sigurnost pohrane podataka najjednostavnije se provodi primjenom sigurnosnih standarda nad samim dokumentima koji se razmijenjuju. Tradicionalni vlastoručni potpis i pečat vrlo se učinkovito nadomještaju s digitalnim potpisom. U ovom su radu analizirani pristupi zaštite sigurnosti sustava te su opisani osnovni standardi za sigurnost e-poslovanja. Opisani standardi verificirani su na Sustavu za razmjenu elektroničkih računa.

Cilj elektroničkog poslovanja jest digitalizirati poslovne procese. Vrlo važan poslovni proces razmjena je elektroničkih računa (e-računa). Razmjena podrazumijeva oblikovanje, slanje, primanje, pohranjivanje i pretraživanje e-računa. U radu će biti prikazan pilotski sustav za razmjenu e-računa oblikovan u sklopu studentskog projekta. Sustav je izgrađen od više raspodijeljenih komponenti povezanih komunikacijskom mrežom. Okosnicu sustava čini središnji poslužitelj sastavljen od središnje baze podataka te web-usluga koje omogućuju razmjenu e- računa. Svaki korisnik ima svoju (fizičku ili logičku) lokalnu bazu podataka u koju pohranjuje poslane i primljene e-račune. Implementiran je i prijedlog sustava registara korisnika e-računa. Korisnici sustavu pristupaju kroz dvije aplikacije: aplikacije za razmjenu e-računa te aplikacije za pristup registru korisnika e-računa.

U ovom radu je opisana izrada Web stranica za jedan studijski primjer, koristeći tehnologije PHP, MySQL i Ajax

Tema ovog rada bilo je stvoriti model za predviđanje rezultata kuglačkih utakmica, a pritom naučiti više o analizi zadanog podatkovnog skupa te baratanju istim. Cilj je svakako bio ostvariti predviđanja koja su približna stvarnima i za pojedinačne rezultate i za ekipne. Korišteno je prediktivno modeliranje kao širi skup. Preciznije, do rezultata se došlo pomoću metoda nadziranog učenja. Model je ostvaren u programskom jeziku R. Rezultati su zadovoljavajući. Predviđanje pobjednika utakmice je uspješno u prosječno 3 od 4 utakmice, a pojedinačni rezultati pripadaju prostoru unutar 5 %. Iako prostora za napredak ima, ovaj rad je pokazao kako kuglanje ipak ima konstantu koja se može iskoristiti za predikcije. Budući rad mogao bi se fokusirati na smanjenje pogreške i odstupanja, testiranje drugih metoda i slično, no metoda nadziranog učenja ispostavila se kao dobra metoda za predviđanje kuglačkih rezultata. The aim of this study was to create a model for predicting the outcomes of bowling matches while gaining a deeper understanding of analyzing the given dataset and handling it effectively. The ultimate goal was to achieve predictions that closely resemble the actual results for both individual and team matches. The chosen approach was predictive modeling, specifically utilizing supervised learning methods and the R programming language as the primary tool. The prediction of match winners was successful in approximately 3 out of 4 matches, and individual scores fell within a 5 % margin. Although there is room for improvement, this study demonstrated that predictive methods can be applied to a sport such as bowling. Future research could focus on reducing errors in individual predictions, exploring alternative methods, and so on. Nonetheless, supervised learning has proven to be an effective approach for predicting 9-pin bowling match results.