19 research outputs found
INTERES ZA DODIPLOMSKI STUDIJ POMORSTVA U SLOVENIJI
Future navigating and engineering officers in Slovenia are educated at a higher education level at the Faculty of Maritime Studies and Transportation, Portorož in two separate courses: Navigation and Mechanical Engineering. The first-year students in both courses, who were registered for the first time, were analyzed for two selected periods of time. For the selected generation of students, the qualities that were important for their success were determined. The final results of the selected generation of final-year students were analyzed and on the basis of this analysis the maritime-programme teachers’ work was assessed and, in addition, recommendation for its improvement were made.Budući časnici palube i stroja obrazuju se u Sloveniji na dodiplomskom studiju Fakulteta za pomorstvo i transport u Portorožu na dva odvojena odjela: nautičkom i brodostrojarskom. Odabrana su dva određena vremenska perioda unutar kojih je izvršena analizana studenta oba smjera koji su prvi puta upisali prvu godinu
studija. Kod odabrane generacije studenata utvrđene su kvalitete koje su neophodne za uspješno studiranje. Konačni rezultati do kojih se došlo kod odabrane generacije studenata završne godine studija podvrgnuti su također analizi, na temelju koje se ocijenio rad predmetnih nastavnika pomorske struke, dajući im istovremeno
i preporuke kako poboljšati i osuvremeniti stručne nastavne predmete
Magnetic Storms and their Influence on navigation
U radu se prikazuju karakteristike Sunčevih i Zemljinih magnetskih polja, njihova međusobna povezanost, ali i njihove anomalije. Broj Sunčevih pjega, koje se povećavaju i smanjuju u nejednakim ciklusima, odgovara broju registriranih magnetskih oluja na Zemlji. Sunčeve plazma-zrake koje izbijaju iz Sunčevih pjega uzrokuju porast broja solarnih vjetrova i pri tome utječu na geomagmetsko polje i Zemljinu atmosferu. Jedan primjer takve uzročne veze bila je najžešća magnetska oluja koja se pojavila u tijeku posljednja dva Sunčeva ciklusa. Trajala je od 28. listopada do 02. studenoga 2003. godine. Uspješna plovidba ovisi o uzimanju u obzir svih promjena na Zemlji koje nastaju zbog promjena na Suncu.This article presents the nature of the Sun’s and Earth’s magnetic fields, their mutual connection and anomalies. The number of sunspots, that increase and decrease in unequal cycles, correspond to the number of registered magnetic storms on the Earth. The Sun’s plasma streams that shoot out from the sunspots cause an increase in the solar winds and in doing so they affect the geomagnetic field and the Earth’s atmosphere. One example of such a causal connection was the most extreme magnetic storm that has occurred during the last two Sun Cycles. It lasted from October 28th to November 2nd 2003. Successful navigation depends on taking into consideration all the changes on the Earth that arises from changes on the Sun
Load Tracking in Road Transport
For the first time in history, remole moniloring and safekeepingof the assels is now possible also during road lransporl.These possibililies were enabled by developmelll of !he informaliontechnology during the last decade. Whereas such developmenlcontinues in a planned direction, !he influence of !heimproved and cheaper means of informal ion upon !he transporicompanies could be foreseen.This arlicle includes !he !ales/ guidelines for !ruck and loadmoniloring syslems develop men!. On the basis of lhese guidelines,!he role of users in !he rem ole monitoring syslems developmentis also presenled. In order lo express !heir problemsmore quickly and lo respond wilh grea/er efficiency, if may benecessmy for !hem lo gel basic knowledge aboul lelecommunicalionand informalics
Određivanje svojstava cementnog gela transverzalnim ultrazvučnim valovima
Sve ne-destruktivne metode za ispitivanje svježog betona posebno su zanimljive, jer omogućavaju predviđanje svojstava betona u njegovoj konačnoj fazi (faza zrelog betona) i to prije njegovog polaganja. Zato je takvim metodama posvećena najveća pažnja. Jedna od uspješnih metoda za određivanje mehaničkih svojstava cementnog gela u trenutku njegovog prelaska u čvrsto stanje, jeste metoda koja koristi refleksiju ultrazvuka pri njegovom prelasku kroz ispitivani uzorak. Metoda se bazira na mjerenju refleksije transverzalnih ultrazvučnih valova od gornjeg sloja cementnog gela u trenutku njegovog stvrdnjavanja korištenjem linije kašnjenja. Moduli elastičnosti i viskoznosti odrede se na osnovi odnosa između prvog i drugog reflektiranog vala. Za mjerenje kinetike hidratacije konstruiran je mjerni sustav u koji su unesene određene popravke za postizanje točnijih rezultata. Pri tom se naročito vodilo računa da se izradi odgovarajuća ispitivačka komora u koju se postavlja uzorak cementnog gela kod ultrazvučnog mjerenja. Uzajamno djelovanje cementnog gela i ultrazvučnih valova može se primijeniti kod ispitivanja kakvoće samog mjerenja kinetike hidratacije uz primjenu mjernih standarda. Pored toga primjena mjernih standarda omogućava još brže određivanje svojstava uzorka, jer se u tom slučaju može iskoristiti podatak o ubrzanju hidratacije. Opisane su i prednosti koje donosi spektralna analiza demoduliranog signala refleksija i spektralna analiza samog signala visoke frekvencije ispred demodulatora.All non-destructive testing methods in civil engineering for fresh concrete are of special interest because they allow predictions to be made about the concrete's properties prior to its placement. That is why the special attention is devoted to such types of the testing method. The Determination of Elastic Properties of Fresh Special Concrete Using Ultrasonic Shear Waves Ultrasonic waves have been used successfully for the determination of the mechanical properties of hardened cement paste and concrete. For this purpose researchers are measuring the ultrasonic shear wave reflections from the upper layer of the hardening cement paste using the buffer rod. The modulus of elasticity and viscosity are determined as a rate between the first and second reflected waves. For measuring of the cement mortar hydration kinetics there has been constructed the measuring setup, which was improved to achieve the more accurate results. The greatest importance is given to the appropriate measuring chamber were the cement gel sample should be inserted, for the ultrasound testing measurements. The interaction between the cement gel and the ultrasonic waves, together with application of the measuring standards, could be used to obtain information on the quality of the cement mortar hydration kinetics measuring process. Besides, usage of the measuring standards enables the earlier determination of the sample properties, because the data on the hydration acceleration is available. There are also described the advantages of the demodulated-reflection-signal spectrum analysis and the spectrum analysis of the high-frequency-signal on the demodulator input
Određivanje svojstava cementnog gela transverzalnim ultrazvučnim valovima
Sve ne-destruktivne metode za ispitivanje svježog betona posebno su zanimljive, jer omogućavaju predviđanje svojstava betona u njegovoj konačnoj fazi (faza zrelog betona) i to prije njegovog polaganja. Zato je takvim metodama posvećena najveća pažnja. Jedna od uspješnih metoda za određivanje mehaničkih svojstava cementnog gela u trenutku njegovog prelaska u čvrsto stanje, jeste metoda koja koristi refleksiju ultrazvuka pri njegovom prelasku kroz ispitivani uzorak. Metoda se bazira na mjerenju refleksije transverzalnih ultrazvučnih valova od gornjeg sloja cementnog gela u trenutku njegovog stvrdnjavanja korištenjem linije kašnjenja. Moduli elastičnosti i viskoznosti odrede se na osnovi odnosa između prvog i drugog reflektiranog vala. Za mjerenje kinetike hidratacije konstruiran je mjerni sustav u koji su unesene određene popravke za postizanje točnijih rezultata. Pri tom se naročito vodilo računa da se izradi odgovarajuća ispitivačka komora u koju se postavlja uzorak cementnog gela kod ultrazvučnog mjerenja. Uzajamno djelovanje cementnog gela i ultrazvučnih valova može se primijeniti kod ispitivanja kakvoće samog mjerenja kinetike hidratacije uz primjenu mjernih standarda. Pored toga primjena mjernih standarda omogućava još brže određivanje svojstava uzorka, jer se u tom slučaju može iskoristiti podatak o ubrzanju hidratacije. Opisane su i prednosti koje donosi spektralna analiza demoduliranog signala refleksija i spektralna analiza samog signala visoke frekvencije ispred demodulatora.All non-destructive testing methods in civil engineering for fresh concrete are of special interest because they allow predictions to be made about the concrete's properties prior to its placement. That is why the special attention is devoted to such types of the testing method. The Determination of Elastic Properties of Fresh Special Concrete Using Ultrasonic Shear Waves Ultrasonic waves have been used successfully for the determination of the mechanical properties of hardened cement paste and concrete. For this purpose researchers are measuring the ultrasonic shear wave reflections from the upper layer of the hardening cement paste using the buffer rod. The modulus of elasticity and viscosity are determined as a rate between the first and second reflected waves. For measuring of the cement mortar hydration kinetics there has been constructed the measuring setup, which was improved to achieve the more accurate results. The greatest importance is given to the appropriate measuring chamber were the cement gel sample should be inserted, for the ultrasound testing measurements. The interaction between the cement gel and the ultrasonic waves, together with application of the measuring standards, could be used to obtain information on the quality of the cement mortar hydration kinetics measuring process. Besides, usage of the measuring standards enables the earlier determination of the sample properties, because the data on the hydration acceleration is available. There are also described the advantages of the demodulated-reflection-signal spectrum analysis and the spectrum analysis of the high-frequency-signal on the demodulator input
Određivanje svojstava cementnog gela transverzalnim ultrazvučnim valovima
Sve ne-destruktivne metode za ispitivanje svježog betona posebno su zanimljive, jer omogućavaju predviđanje svojstava betona u njegovoj konačnoj fazi (faza zrelog betona) i to prije njegovog polaganja. Zato je takvim metodama posvećena najveća pažnja. Jedna od uspješnih metoda za određivanje mehaničkih svojstava cementnog gela u trenutku njegovog prelaska u čvrsto stanje, jeste metoda koja koristi refleksiju ultrazvuka pri njegovom prelasku kroz ispitivani uzorak. Metoda se bazira na mjerenju refleksije transverzalnih ultrazvučnih valova od gornjeg sloja cementnog gela u trenutku njegovog stvrdnjavanja korištenjem linije kašnjenja. Moduli elastičnosti i viskoznosti odrede se na osnovi odnosa između prvog i drugog reflektiranog vala. Za mjerenje kinetike hidratacije konstruiran je mjerni sustav u koji su unesene određene popravke za postizanje točnijih rezultata. Pri tom se naročito vodilo računa da se izradi odgovarajuća ispitivačka komora u koju se postavlja uzorak cementnog gela kod ultrazvučnog mjerenja. Uzajamno djelovanje cementnog gela i ultrazvučnih valova može se primijeniti kod ispitivanja kakvoće samog mjerenja kinetike hidratacije uz primjenu mjernih standarda. Pored toga primjena mjernih standarda omogućava još brže određivanje svojstava uzorka, jer se u tom slučaju može iskoristiti podatak o ubrzanju hidratacije. Opisane su i prednosti koje donosi spektralna analiza demoduliranog signala refleksija i spektralna analiza samog signala visoke frekvencije ispred demodulatora.All non-destructive testing methods in civil engineering for fresh concrete are of special interest because they allow predictions to be made about the concrete's properties prior to its placement. That is why the special attention is devoted to such types of the testing method. The Determination of Elastic Properties of Fresh Special Concrete Using Ultrasonic Shear Waves Ultrasonic waves have been used successfully for the determination of the mechanical properties of hardened cement paste and concrete. For this purpose researchers are measuring the ultrasonic shear wave reflections from the upper layer of the hardening cement paste using the buffer rod. The modulus of elasticity and viscosity are determined as a rate between the first and second reflected waves. For measuring of the cement mortar hydration kinetics there has been constructed the measuring setup, which was improved to achieve the more accurate results. The greatest importance is given to the appropriate measuring chamber were the cement gel sample should be inserted, for the ultrasound testing measurements. The interaction between the cement gel and the ultrasonic waves, together with application of the measuring standards, could be used to obtain information on the quality of the cement mortar hydration kinetics measuring process. Besides, usage of the measuring standards enables the earlier determination of the sample properties, because the data on the hydration acceleration is available. There are also described the advantages of the demodulated-reflection-signal spectrum analysis and the spectrum analysis of the high-frequency-signal on the demodulator input
Measuring and Modelling of the Traffic Flow at Microscopic Level
The traffic flow theory is dealing with the better understandingof the traffic flow and its improvement. Most often, the researchedsubject was been the road traffic. It is namely thatheavy traffic and traffic jams are the frequent phenomena onthe roads.The traffic flow theory incorporates the different areas ofknowledge necessary to establish a successful traffic-flow simulationmodel. Good correlation between the simulation modelresults and data collected in the open road conditions are notthe only conditions which are necessary to approve the simulationmodel as accurate. The obtained simulation results may beused for the improvement of traffic conditions, only if themodel obeys the classical laws of physics.This paper is dealing with the simple microscopic model fortwo-vehicle-platoon behaviour in the traffic flow. The model isbased on solving of the delay differential equations. The simulationmodel results have been compared with the measurementresults. The comparison has enabled assessment of the selectedsimulation model to check whether it would be goodchoice for further traffic-flow researches at the microscopiclevel
Vehicle-Driver Behavioural-Responses Defined by Radio-Navigation System GPS
From the very beginning of its usage the navigation systemGPS has been applied in studying the cases of the car followingbehaviour of two-vehicle platoons. The navigation receiver isused for vehicle position and speed data collections. The measurementaccuracy is to be improved by the real-time dGPScorrection-data or by additional data post-processing. For additionalmeasurement of the vehicle-to-vehicle separation, bothvehicles should be equipped with a GPS receiver. The vehicle-to-vehicle separation is calculated later on, during the datapost-processing.This paper describes the choice of the experimental setup,on the basis of the radio-navigation system GPS, which may beused for recording the data on location, speed and time. Thepresented measurement results have been attained in two steps:first, the data were collected, through the process of tracking oftwo-vehicle platoons in real life traffic-flow, and then processed.The selected mathematical model is based on the PIDcontroller in the closed-loop control system. It enables evaluationof the measurement results and assessment of the behaviouralelements of each driver
SUNSPOT CYCLES IMPACTS ON TOURISM AND QUALITY OF LIFE
We live under the influence of natural cycles caused by the rotation of our planet and its revolution around the sun. The nature of our nearest star is also subject to cyclical change. This article presents a study of a correlation between sunspot cycles and foreign tourists arrivals in Slovenia, based on historical data between sunspot cycles and sea salt production in Slovenia's Municipality of Piran during the Maunder Minimum period (1645-1715). The production of salt by the solar evaporation of brine in salt pans and tourist industry are seasonal economic activities that are affected by changes to the weather. The paper looks at sea salt production in Piran during a particular period in the past. The repetition of the sea salt production in the past is not possible. For this reason, the study uses mathematical tools and an additional case study, which analyses arrivals of foreign tourists to Slovenia over the past 65 years (1948-2012). The study has two purposes: to identify a linear correlation coefficient, which provides evidence of a correlation between arrivals of foreign tourists to Slovenia and sunspot cycles and to develop a causal loop diagram (CLD) or so called qualitative model of a complex tourism system, which shows the interdependency of sunspot cycles, tourism system, and quality of life