| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


41 - 50 / 628
Na začetekNa prejšnjo stran12345678910Na naslednjo stranNa konec
41.
Comparison of methods for determination of polyphenols in wine by HPLC-UV/VIS, LC/MS/MS and spectrophotometry
Vesna Mila Meden, Matija Strlič, Drago Kočar, 2009, izvirni znanstveni članek

Opis: Phenolic antioxidants are usually grouped into flavonoids and non-flavonoids, according to their structure. With regard to the tannic character, phenolic antioxidants are further subdivided to tannic phenols and non-tannic phenols. Collectively, these compounds contribute to the high antioxidant capacity of wine. In this work, we compare determination of gallic acid, catechin, epicatechin, resveratrol, quercetin, dihydrobenzoic acid, sinapic acid, vanillic acid, caffeic acid, chlorogenic acid, ferullic acid, ellagic acid, p-coumaric acid and caftaric acid in 141 wine samples using two liquid chromatographic methods and detection systems, i.e. with UV detection and mass-spectrometric detection. In addition, we applied the conventional Folin-Ciocalteu spectrophotometric method for determination of the total phenolic content in wine samples and compared the results with those obtained using the chromatographic methods. Despite satisfactory correlations statistically significant differences between HPLC-UV/VIS and LC/MS/MS were established, which could be related to coelution not detectable with UV/VIS detectors. The correlations between results of the spectrophotometric method and sum of LC/MS/MS determinations are not satisfactory and are different for white, red, and rosé wines.
Ključne besede: food analysis, wine, antioxidants, chromatography
Objavljeno v DKUM: 17.08.2017; Ogledov: 2031; Prenosov: 153
.pdf Celotno besedilo (185,67 KB)
Gradivo ima več datotek! Več...

42.
Suitability of the double Langevin function for description of anhysteretic magnetization curves in NO and GO electrical steel grades
Simon Steentjes, Martin Petrun, G. Glehn, Drago Dolinar, Kay Hameyer, 2017, izvirni znanstveni članek

Opis: This paper compares the match obtained using the classical Langevin function, the tanh function as well as a recently by the authors proposed double Langevin function with the measured anhysteretic magnetization curve of three different non-oriented electrical steel grades and one grain-oriented grade. Two standard non-oriented grades and a high-silicon grade (Si content of 6.5%) made by CVD are analyzed. An excellent match is obtained using the double Langevin function, whereas the classical solutions are less appropriate. Thereby, problems such as those due to propagation of approximation errors observed in hysteresis modeling can be bypassed.
Ključne besede: polarization, magnetization measurement, magnetic materials, hysteresis models, Langevin function, electrical steel, saturation
Objavljeno v DKUM: 03.08.2017; Ogledov: 1094; Prenosov: 406
.pdf Celotno besedilo (652,05 KB)
Gradivo ima več datotek! Več...

43.
Rate-dependent extensions of the parametric magneto-dynamic model with magnetic hysteresis
Simon Steentjes, Martin Petrun, G. Glehn, Drago Dolinar, Kay Hameyer, 2017, izvirni znanstveni članek

Opis: This paper extends the parametric magneto-dynamic model of soft magnetic steel sheets to account for the phase shift between local magnetic flux density and magnetic field strength. This phase shift originates from the damped motion of domain walls and is strongly dependent on the microstructure of the material. In this regard, two different approaches to include the rate-dependent effects are investigated: a purely phenomenological, mathematical approach and a physical-based one.
Ključne besede: magnetic hysteresis, eddies, magnetic flux, viscosity, magnetic fields, magneto-dynamic models, parametric
Objavljeno v DKUM: 03.08.2017; Ogledov: 1106; Prenosov: 401
.pdf Celotno besedilo (567,72 KB)
Gradivo ima več datotek! Več...

44.
Prediction of standard lactation curves for primiparous Holstein cows by using corrected regression models
Janez Jeretina, Drago Babnik, Dejan Škorjanc, 2015, izvirni znanstveni članek

Opis: Prediction of the expected milk yield is important for the management of the primiparous cows (PPC) with a few or no data on their own milk productivity. We developed a system of regression equations for predicting milk yields in standard lactation. The models include the systematic effects of the calving season, the five-year rolling herd average of milk yield of PPC, the breeding values of the parents for milk production, and daily milk recordings. A total of 21,901 lactations of Holstein PPC were collected during the regular monthly milk recordings of cows in the Republic of Slovenia. By including daily milk recordings in the model, the coefficients of determination of regression models for the prediction of milk yield increase: without known recordings (M0) R 2 =0.80; with one recording (M1) R 2 =0.82; with two first consecutive recordings (M2) R 2 =0.86; and with three recordings (M3) R 2 =0.89. Deviations of milk yield up to 500 kg in a standard lactation (<1.6 kg/day) were as follows: with the model M0, they occurred in 53.4% of PPC; with M1, they occurred in 56.3% of PPC; with M2, they occurred in 64.5% of PPC; and with M3, they occurred in 70.9% of PPC. We concluded that the developed system of regression models is an appropriate method for milk yield prediction of PPC.
Ključne besede: primiparous cows, milk yield, prediction, lactation curves, regression equations
Objavljeno v DKUM: 24.07.2017; Ogledov: 1210; Prenosov: 484
.pdf Celotno besedilo (497,85 KB)
Gradivo ima več datotek! Več...

45.
Environmental data exchanging – the need for management
Drago Vuk, 2000, kratki znanstveni prispevek

Opis: In this paper, the author analyses the beginning of the application of measures imposed by the Slovenian Law on the Environmental Protection and the Environmental Information System. On the basis of his knowledge of the actual state, he proposes a model by means of which it would be possible to systematically assure with EDI environmental balances and environmental accounting, thus providing the basis for the implementation of an applicable environmental information system.
Ključne besede: environmental protection, environmental data, electronic data interchange
Objavljeno v DKUM: 17.07.2017; Ogledov: 1212; Prenosov: 130
.pdf Celotno besedilo (251,75 KB)
Gradivo ima več datotek! Več...

46.
Vplivi različnih načinov vodenja sistema za uporovno točkovno varjenje na njegove izgube
Jernej Černelič, 2017, doktorska disertacija

Opis: V doktorski disertaciji je predstavljen srednje-frekvenčni sistem za uporovno točkovno varjenje (UTV) s katerim se v industriji varijo pločevine. Tak sistem je sestavljen iz frekvenčnega pretvornika, transformatorja, diodnega usmernika in varilnih klešč ter varjenih pločevin. S frekvenčnim pretvornikom lahko generiramo poljubne dolžine pulzov napetosti, s katero nato napajamo transformator. Posledično pa lahko uporabimo različne metode generiranja pulzov napajalne napetosti. V industriji se v ta namen najpogosteje uporablja pulzno-širinska modulacija, ki ji moramo definirati modulacijsko frekvenco, ki je pogosto konstantna. Ker lahko generiramo poljubne dolžine pulzov napajalne napetosti, pa lahko te prožimo tudi glede na potrebe procesa UTV. V disertaciji je tako predstavljen algoritem histereznega vodenja sistema za UTV, ki transformator napaja z minimalno frekvenco napajalne napetosti, ki jo sistem potrebuje, da lahko zagotovi želen bremenski tok. Pri tem pa se lahko frekvenca napajalne napetosti med obratovanjem tudi spremeni, kar ni značilno za pulzno-širinsko modulacijo. Zaradi spreminjanja frekvence napajalne napetosti v disertaciji obravnavamo število pulzov napajalne napetosti v enako dolgih varilnih ciklih. Spreminjanje frekvence pa vpliva na tako imenovane dinamične izgube sistema za UTV, ki so odvisne od frekvence napajalne napetosti. Med te izgube uvrščamo stikalne izgube frekvenčnega pretvornika, izgube povezane s kožnim pojavom v navitjih transformatorja in histerezne izgube železnega jedra transformatorja za UTV. Z zmanjšanjem frekvence se te običajno zmanjšajo, kar smo potrdili tudi v primeru sistema za UTV. Pri uporabi algoritma histereznega vodenja, ki transformator napaja z minimalno frekvenco napajalne napetosti pa naraste valovitost bremenskega toka. Ta je lahko še posebej velika pri varjenju pločevin z nizko vrednostjo nadomestne varilne upornosti. Za tak primer smo pripravili tudi algoritem vodenja, ki zmanjša valovitost bremenskega toka na polovico tako, da maksimalno dolžino pulza napajalne napetosti prepolovi. Pri tem algoritem vodenja samodejno določi dolžino pulza napajalne napetosti na podlagi prvega pulza napajalne napetosti, ki vrednost gostote magnetnega pretoka spremeni od ene točke nasičenja do druge. Oba razvita algoritma pa lahko uporabljamo tudi pri DC-DC pretvornikih, ki vsebujejo transformator. V disertaciji pa smo analizirali tudi vplive bremenskega toka, nadomestne upornosti bremena in napetosti enosmernega vodila na obremenitev sistema. Od obremenitve je namreč odvisno koliko bo lahko algoritem vodenja znižal frekvenco oziroma zmanjšal število pulzov napajalne napetosti. Na podlagi te analize lahko izberemo tak nabor varilnih parametrov, pri katerih bo izkoristek sistema za UTV največji. Vrednosti varilnih parametrov lahko namreč tudi nekoliko spremenimo, pri tem pa se kvaliteta nastalega spoja ne spremeni.
Ključne besede: uporovno točkovno varjenje, regulacija, histerezna regulacija, nasičenje, algoritem vodenja, minimalna frekvenca, izgube, izkoristek, valovitost bremenskega toka, frekvenčni pretvornik
Objavljeno v DKUM: 05.07.2017; Ogledov: 1731; Prenosov: 74
.pdf Celotno besedilo (9,12 MB)

47.
The role of environmental management
Drago Vuk, 1998, izvirni znanstveni članek

Opis: Unlike the currently experienced practice, author offers a new approach to the environmental protection issue. To different types of management he adds the environmental component , which has attained a notable level, both as a contribution to the subject of successful development of the economy, and on the implementation level, where it can serve as one of the sources of competitive advantage.
Ključne besede: management, environment, ecology
Objavljeno v DKUM: 04.07.2017; Ogledov: 1374; Prenosov: 95
.pdf Celotno besedilo (478,50 KB)
Gradivo ima več datotek! Več...

48.
The impact of regulation 561/2006 on fleet management viewed through efficient use of drivers' working time
Robert Muha, Drago Sever, 2009, pregledni znanstveni članek

Opis: The introduction of contemporary procedures to fleet management processes has recently changed the work planning and supervision of driver's work activities. Tendencies to control the implementation of driver's work have been present in modem professional practice for quite a long time; however, the equipment available on the market limited its implementation. The intensified development of digital tachographs has, in technical terms, ensured such equipment considerably before the legislative groundwork was prepared for its practical implementation. The Commission Regulation (EC) No. 561/2006 (implementation of Social legislation relating to Road Transport) does not bring any essential novelties in terms of permitted workload. Consistent monitoring of drivers activities, made possible by digital tachographs, will have impact on the existing working methods. The topic of the present paper is in deep analysis of the impact of the mentioned regulation with special emphasis on the conditions for the regulation of the current stage of drivers work and on the expected consequences. The essential importance lies on the expected change in the mentality and approach to planning the driver's activities in the transport process on the part of the carrier: the outcome will eventually result in the efficiency of each individual carrier.
Ključne besede: fleet management, driver's work planning, digital tachographs
Objavljeno v DKUM: 06.06.2017; Ogledov: 1059; Prenosov: 492
.pdf Celotno besedilo (2,98 MB)
Gradivo ima več datotek! Več...

49.
Simulation of crossroad traffic
Boris Tovornik, Drago Sever, Daniel Rogač, 2000, kratki znanstveni prispevek

Opis: It is difficult to find the right tool for making traffic regime models because so many different situations are involved. Simulink has proved to be one of the best. The paper shows the design and the use of components and models in the program Matlab/SIMULINK. It presents the simulation results for the model of a traffic light controlled crossroad and indicates the possibilities for the study of traffic optimisation in junctions.
Ključne besede: traffic, traffic light controlled crossroads, simulation, optimization
Objavljeno v DKUM: 05.06.2017; Ogledov: 1162; Prenosov: 147
.pdf Celotno besedilo (1,93 MB)
Gradivo ima več datotek! Več...

50.
Real capacity of ropeway transportation subsystem
Drago Sever, 2000, kratki znanstveni prispevek

Opis: The ropeway transportation system plays a major role in mountain resorts. In order to provide a sustainable development of the entire mountain resort system, the real capacity of the ropeway transportation system was set. The real capacity of the ropeway transportation system is one of the indicators of the development harmonisation level of single system elements. The research into this field was carried out at the Road Traffic Centre of the Faculty of Civil Engineering, University of Maribor. The paper deals with the basic points of the topic and the methods used. The know-how transfer of experiences into the Slovenian environment is presented together with the obtained results.
Ključne besede: traffic management, traffic, transport, ropeway, capacity
Objavljeno v DKUM: 05.06.2017; Ogledov: 1190; Prenosov: 154
.pdf Celotno besedilo (2,01 MB)
Gradivo ima več datotek! Več...

Iskanje izvedeno v 0.21 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici