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Reverse logistics
No full textPovratna logistika bavi se upravljanjem obrnutim tokovima proizvoda i materijala,
odnosno distribucijom robe od kupca prema prodavaču ili proizvođaču. Ključni aspekt povratne
logistike je efikasno upravljanje ciklusom vraćanja proizvoda i materijala iz potrošačke faze
natrag u opskrbni lanac s ciljem recikliranja, ponovne uporabe ili ponovne proizvodnje. Cilj
rada je prikazati značajke i ulogu povratne logistike na temelju sekundarnih izvora podataka i
analize poslovanja odabranog poslovnog subjekta. Analizirani su različiti aspekti povratne
logistike i istraženo je kako efikasno integrirati povratne tokove materijala i proizvoda unutar
opskrbnih lanaca s ciljem smanjenja negativnog utjecaja na okoliš, optimizacije resursa te
unaprjeđenja ekonomske izvedivosti. Na primjeru online trgovine ASOS, pokazano je kako
logistika povrata pozitivno utječe na poslovanje, odnosno jača konkurentnost, štiti okoliš,
doprinosi društvenoj odgovornosti, a samim time i imidžu kompanije.Reverse logistics deals with the management of the reverse flow of products and
materials, i.e. the distribution of goods from the customer to the seller or manufacturer. A key
aspect of reverse logistics is the efficient management of the returning products process from
the consumer back into the supply chain with the aim of recycling, re-use or re-production. The
aim of the paper is to present the features and role of reverse logistics based on secondary data
sources and analysis of the operations of the selected business entity. Different aspects of
reverse logistics were analyzed and it was investigated how to efficiently integrate the return
flows of materials and products within supply chains with the aim of reducing the negative
impact on the environment, optimizing resources and improving economic feasibility. Using
the example of the ASOS online store, it was shown how reverse logistics positively affects
business, i.e. strengthening competitiveness, protecting the environment and contributing to
social responsibility and thus the company's image
A New Approach for Improving GNSS Geodetic Position by Reducing Residual Tropospheric Error (RTE) Based on Surface Meteorological Data
No full textPositioning error components related to tropospheric and ionospheric delays are caused by the atmosphere in positioning determined by global navigation satellite systems (GNSS). Depending on the user’s requirements, the position error caused by tropospheric influences, which is commonly referred to as zenith tropospheric delay (ZTD), must be estimated during position determination or determined later by external tropospheric corrections. In this study, a new approach was adopted based on the reduction of residual tropospheric error (RTE), i.e., the unmodeled part of the tropospheric error that remains included in the total geodetic position error, along with other unmodeled systematic and random errors. The study was performed based on Global Navigation Satellite System (GLONASS) positioning solutions and accompanying meteorological parameters in a defined and harmonized temporal-spatial frame of three locations in the Republic of Croatia. A multidisciplinary approach-based analysis from a navigational science aspect was applied. The residual amount of satellite positioning signal tropospheric delay was quantitatively reduced by employing statistical analysis methods. The result of statistical regression is a model which correlates surface meteorological parameters with RTE. Considering the input data, the model has a regional character, and it is based on the Saastamoinen model of zenith tropospheric delay. The verification results show that the model reduces the RTE and thus increases the geodetic accuracy of the observed GNSS stations (with horizontal components of position accuracy of up to 3.8% and vertical components of position of up to 4.37%, respectively). To obtain these results, the Root Mean Square Error (RMSE) was used as the fundamental parameter for position accuracy evaluation. Although developed based on GLONASS data, the proposed model also shows a considerable degree of success in the verification of geodetic positions based on Global Positioning System (GPS). The purpose of the research, and one of its scientific contributions, is that the proposed method can be used to quantitatively monitor the dynamics of changes in deviations of X, Y, and Z coordinate values along coordinate axes. The results show that there is a distinct interdependence of the dynamics of Y and Z coordinate changes (with almost mirror symmetry), which has not been investigated and published so far. The resultant position of the coordinates is created by deviations of the coordinates along the Y and Z axes—in the vertical plane of space, the deviations of the coordinate X (horizontal plane) are mostly uniform and independent of deviations along the Y and Z axes. The proposed model shows the realized state of the statistical position equilibrium of the selected GNSS stations which were observed using RTE values. Although of regional character, the model is suitable for application in larger areas with similar climatological profiles and for users who do not require a maximum level of geodetic accuracy achieved by using Satellite-Based Augmentation Systems (SBAS) or other more advanced, time- consuming, and equipment-consuming positioning techniques
Method for Automatic Estimation of Instantaneous Frequency and Group Delay in Time-Frequency Distributions with Application in EEG Seizure Signals Analysis
No full textInstantaneous frequency (IF) is commonly used in the analysis of electroencephalogram (EEG) signals to detect oscillatory-type seizures. However, IF cannot be used to analyze seizures that appear as spikes. In this paper, we present a novel method for the automatic estimation of IF and group delay (GD) in order to detect seizures with both spike and oscillatory characteristics. Unlike previous methods that use IF alone, the proposed method utilizes information obtained from localized Rényi entropies (LREs) to generate a binary map that automatically identifies regions requiring a different estimation strategy. The method combines IF estimation algorithms for multicomponent signals with time and frequency support information to improve signal ridge estimation in the time–frequency distribution (TFD). Our experimental results indicate the superiority of the proposed combined IF and GD estimation approach over the IF estimation alone, without requiring any prior knowledge about the input signal. The LRE-based mean squared error and mean absolute error metrics showed improvements of up to 95.70% and 86.79%, respectively, for synthetic signals and up to 46.45% and 36.61% for real-life EEG seizure signals
Safety settings of electronic chart display and information system
No full textMeđunarodna pomorska organizacija donosi pravila i propise u svrhu vođenja sigurne navigacije. Kroz svoja pravila i zahtjeve, uz suradnju s drugim organizacijama doneseni su standardi i zakoni vezani za vođenje sigurne navigacije na informacijskom sustavu i prikazu elektroničkih karata. Zakoni koji su doneseni propisuju minimalne uvjete koje sustav mora ispuniti u pogledu integracije sustava s drugim navigacijskim uređajima i koje se vrste elektroničkih karata koriste i na koji način se podaci s tih karata moraju prikazati na zaslonu sustava. Osim prikaza elektroničkih karata, propisano je kako sustav mora davati i određene informacije u pogledu vođenja sigurne navigacije. Jedne od tih informacija jesu postavke sigurnosnih dubina i sigurnosne margine, te kako sustav daje upozorenja za sigurnost navigacije na temelju ovih parametara i kako se ovi parametri postavljaju da bi se zadovoljio pojam sigurne navigacije.The International Maritime Organization provides with rules and regulations for the purpose of conducting safe navigation. Through these regulations, in cooperation with other organizations, standards and requirements related to safe navigation on the electronic charts display and information system have been adopted. Regulations that have been passed dictate the minimum requirements that the system must meet regarding the integration with other navigation devices and what types of electronic charts are used and how the data from these charts must be displayed on the system display. In addition to the display of electronic charts, it is stipulated that the system must also provide certain information regarding safe navigation. One of this information is the settings of safety depths and safety margins, as well, how the system gives navigation safety warnings based on these parameters and how these parameters are set to meet the concept of safe navigation
Model of autonomous ships for the search and resque system at sea
No full textTraganje i spašavanje na moru predstavlja neke od najkompleksnijih radnji u pomorskom prometu. Često suočeni s otežanim uvjetima traganja i spašavanja, zapovjednici brodova i koordinatori spasilačkih akcija moraju imati na umu velik broj parametara po kojima će organizirati spašavanje i osigurati optimalan ishod istog.
Modeli autonomnih brodova predstavljaju jedan od najvažnijih suvremenih nastojanja u pomorskim znanostima. Od brodogradnje, pa sve do traganja i spašavanja na moru, autonomni se brodovi razvijaju s namjerom da povećaju sigurnost plovidbe, smanje kako troškove prijevoza tako i potrošnju goriva, ali i kao odgovor na manjak obrazovanog i obučenog osoblja kada je u pitanju pomorstvo kao takvo. Kada je riječ o traganju i spašavanju na moru, autonomni brodovi predstavljaju važnu inovaciju koja ima potencijala potpuno ukloniti faktor ljudske pogreške te predvidjeti neke od opasnih nadolazećih okolnosti i na taj način spasiti više ljudskih života, svevremeno štedeći na naporima, materijalima i najvažnije vremenu koje je potrebno da se optimizira ustanovljena teška situacija. Radi se o važnoj tehnologiji čiji razvoj obilježava početak 21. stoljeća u pomorstvu, a izvjesno je da će današnji studenti pomorstva imati priliku raditi na ili pri nekim od ovih brodova, s obzirom na to da se ove inovacije odnose na poboljšanje ne samo pomorstva i osiguranje ljudskih života, već i na održivost pomorske kulture, ali i pomorskog ekosustava kao takvog.Search and rescue at sea represents some of the most complex operations in maritime transport. Often faced with difficult search and rescue conditions, ship captains and rescue coordinators must keep in mind a large number of parameters by which they will organize the rescue and ensure its optimal outcome.
Autonomous ship models represent one of the most important contemporary endeavors in maritime sciences. From shipbuilding to search and rescue at sea, autonomous ships are being developed with the intention of increasing the safety of navigation, reducing both transportation costs and fuel consumption, but also as a response to the lack of educated and trained personnel when it comes to maritime as such. When it comes to search and rescue at sea, autonomous ships represent an important innovation that has the potential to completely eliminate the factor of human error and predict some of the dangerous upcoming circumstances and thus save more human lives, all the while saving efforts, materials and most importantly time necessary to optimize the established difficult situation. It is an important technology whose development marks the beginning of the 21st century in maritime affairs, and it is certain that today's maritime students will have the opportunity to work on or with some of these ships, given that these innovations relate to the improvement of not only maritime affairs and insurance human lives, but also on the sustainability of maritime culture, but also of the maritime ecosystem as such
Measuring instruments, devices and locations in ships propulsion complex
No full textBrodski strojni kompleks složen je niz sustava i podsustava koji zahtijeva konstantan nadzor. Međutim za ostvarivanje opisanog, potrebno je primijeniti odgovarajuće mjerene instrumente i uređaje te određeni oblik logike prilikom njihovog pozicioniranja unutar nadziranog sustava. Logika pozicioniranja ponajprije je definirana tehničkim pravilima klasifikacijskih društava za granju bodova, dok u manjoj mjeri iskustvom. Opisani pristup u konačnici rezultira jednostavnijom dijagnostikom te smanjenim brojem zastoja, pritom osiguravajući učinkovit i siguran način rada.Ships propulsion complex is a complex series of systems and subsystems that requires constant monitoring. However, to achieve the described, it is necessary to apply appropriate measuring instruments and devices along with a certain form of positioning logic. The logic behind positioning is primarily defined by the technical rules of classification societies, while to a lesser extent by experience. The described approach ultimately results in simpler diagnostics and a reduced number of downtimes, while ensuring efficiency and safety
Tourism and sustainable development
No full textFokus ovog rada stavljen je na istraživanje održivog razvoja i održivog turizma. Ova dva usko povezana pojma su pokazatelj kako se može zaštititi okoliš, postojeći i novi resursi, samim time i poboljšati život trenutnih, a ujedno i budućih generacija. Održivi turizam ima veliku važnost i za Republiku Hrvatsku, koja je sastavila strategiju razvoja održivog turizma. Ovom strategijom pokušat će se zaštiti okoliš i resursi, ali i povećati broj turista van ljetnih mjeseci. Primorsko-goranska županija ima veliki potencijal da se promakne u vodeću županiju koja svojim djelovanjem može biti primjer ostatku države.The focus of this thesis is on the research of sustainable development and sustainable tourism. These two closely related concepts are an indicator of how to protect the environment, existing and new resources, and thus improve the life of current and future generations. Sustainable tourism is also of great importance for the Republic of Croatia, which has drawn up a strategy for the development of sustainable tourism. This strategy will attempt to protect the environment and resources, but also increase the number of tourists outside of the summer months. The Primorsko-goranska county has great potential to become a leading county, which can set an example for the rest of the country through its activities
Determining the position of the ship using the Sun in the time interval (Running fix)
No full textNebeska navigacija predstavlja korištenje promatranih položaja nebeskih tijela za određivanje
položaja plovila. U svakom trenutku neko nebesko tijelo, najčešće Sunce, nalazi se u zenitu
bilo kojeg određenog mjesta na površini zemlje. Iz ovih informacija može se iscrtati linija
položaja. Navigator zatim koristi sekstant za mjerenje visine nebeskog objekta i bilježi tu
visinu, s pomoću koje procjenjuje svoj položaj. Visina i smjer koji bi nebesko tijelo imalo na
tom položaju izračunavaju se ili uzimaju iz tablica. Iz ovih informacija i iz razlike između
opažene i izračunate visine nebeskog objekta, može se izračunati položaj plovila. Određivanje
pozicije broda metodama astronomske navigacije predstavlja vrlo staru vještinu koja se
koristila sve do dolaska suvremen tehnologija koja omogućava vrlo precizno određivanje
položaja. Koriste se različite metode, ovisno o potrebama, a Sunce je najčešći nebeski objekt
koji služi za određivanje položaja.Celestial navigation is the use of observed positions of celestial bodies to determine the
position of the vessel. At any moment, a celestial body, most often the sun, is at the zenith of
any particular place on the earth's surface. A position line can be drawn from this information.
The navigator then uses a sextant to measure the altitude of the celestial object and records
that altitude, which he uses to estimate his position. The altitude and direction that the
celestial body would have at that position are calculated or taken from tables. From this
information and from the difference between the observed and calculated height of the
celestial object, the position of the vessel can be calculated. Determining a ship's position
using astronomical navigation methods is a historical skill that was used until the arrival of
modern technology that enables very precise position determination. Different methods are
used, depending on the needs, and the sun is the most common celestial object used to
determine the position
Human factor and the prevention of collisions at sea
No full textSudari na moru predstavljaju katastrofalne događaje koji mogu dovesti do gubitka života, ekološke štete i značajnih ekonomskih posljedica. Sudari su najčešće rezultat pogreške ili nemara najmanje jednog, a često i više, časnika (navigatora, pomoraca) na brodovima koji sudjeluju u sudaru, odnosno da je u 90% slučajeva uzrok sudara baš ljudski faktor. Ljudski element je najnepredvidljiviji faktor s obzirom na to da svatko ima drugačije ponašanje i razumijevanje, sposobnost ljudi da se sigurno i učinkovito nose sa složenošću, pritiscima, radnim opterećenjem ili poteškoćama svakodnevnih zadataka te se ono, ne samo u hitnim situacijama nego i tijekom svakodnevne rutine, može se razlikovati. Stoga temelj uspješnosti posade leži u njihovom pomorskom obrazovanju, posebice sveobuhvatnoj obuci zapovjednika i časnika. Obrazovanje služi kao kamen temeljac njihove kompetencije, opremajući ih potrebnim vještinama za rješavanje raznih situacija na moru. Ovisno o njihovim specifičnim pozicijama na brodu, svaki član posade stječe posebna znanja relevantna za njihove uloge tijekom brodskih operacija. Pomorska industrija svjedočila je brojnim sudarima na moru koji su doveli do značajnih posljedica i vrijednih lekcija za poboljšanje sigurnosti i sprječavanje budućih incidenata. Kroz analizu studija slučaja, istraživanja i uvida u industriju, ovaj rad je rasvijetlio višestruku prirodu ljudskih čimbenika koji pridonose sudarima između brodova. Ovi čimbenici variraju od propusta u prosudbi do neuspjeha u učinkovitom komuniciranju namjera. Ipak, ključna lekcija koja se nameće jest da ti ljudski čimbenici nisu inherentne slabosti, već prije izazovi koji se mogu riješiti kroz sveobuhvatne strategije.Collisions at sea are catastrophic events that can lead to loss of life, environmental damage and significant economic consequences. Collisions are most often the result of the error or negligence of at least one, and often more, officers (navigators, sailors) on the ships participating in the collision, that is, in 90% of cases the cause of the collision is the human factor. The human element is the most unpredictable factor considering that everyone has a different behavior and understanding, the ability of people to safely and effectively deal with the complexity, pressures, workload or difficulties of daily tasks and that, not only in emergency situations but also during daily routine , may differ. Therefore, the basis of the crew's success lies in their maritime education, especially the comprehensive training of commanders and officers. Education serves as the cornerstone of their competence, equipping them with the necessary skills to handle various situations at sea. Depending on their specific positions on board, each crew member acquires specific knowledge relevant to their roles during shipboard operations. The maritime industry has witnessed numerous col-lisions at sea that have led to significant consequences and valuable lessons for improving safety and preventing future incidents. Through case study analysis, research and industry insights, this paper has shed light on the multifaceted nature of human factors that contribu-te to collisions between ships. These factors range from lapses in judgment to failure to ef-fectively communicate intentions. However, the key lesson that emerges is that these human factors are not inherent weaknesses, but rather challenges that can be addressed through comprehensive strategies
Implementing the FMEA method in preventive maintenance
No full textU završnom radu je opisano preventivno održavanje i koliko je ono važno za duži vijek trajanja nekog proizvoda ili sustava, te za upravljanje njihovom kvalitetom. Kao dio preventivnog održavanja također je pojašnjena i Analiza utjecaja i posljedica pogrešaka (FMEA) koja je velika pomoć kod procjene rizika i sprječavanja nastanka potencijalnih pogrešaka, njezinih uzroka i posljedica. Prikazana je primjena FMEA metode u analizi kvarova automobila, te procjene glavnih parametara analize. Nakon procjena navedene su preventivne mjere koje su potrebne da bi se spriječili potencijalni kvarovi, smanjili troškovi, sačuvala zadana funkcija za pravilan i siguran rad automobila.The undergraduate thesis describes preventive maintenance and how important it is for the longer duration of a product or system, and for the management of their quality. As part of preventive maintenance, Failure Modes and Effects Analysis (FMEA) has also been clarified, which is a major help in risk evaluation and prevention of potential failure, their causes and consequences. Implementation of FMEA method is presented in the analysis of car failures and also the evaluation of the main parameters of analysis. Preventive measures, which are necessary for preventing potential failures, reducing costs, preserving the default function for proper and safe operation of the car, are listed after the evaluation