Quantifying soil complexity using network models of soil porous structureMarko Samec
, A. Santiago
, J. P. Cardenas
, R. M. Benito
, A. M. Tarquis
, Sacha Jon Mooney
, Dean Korošak
, 2013, izvirni znanstveni članek
Opis: This paper describes an investigation into the properties of spatially embedded complex networks representing the porous architecture of soil systems. We suggest an approach to quantify the complexity of soil pore structure based on the node-node link correlation properties of the networks. We show that the complexity depends on the strength of spatial embedding of the network and that this is related to the transition from a non-compact to compact phase of the network.
Ključne besede: soil complexity, soil pore networks, complex systems
Objavljeno: 21.07.2017; Ogledov: 91; Prenosov: 2
Celotno besedilo (3,85 MB)
Drago Pupavac: Logistički operator - čimbenik dinamičke optimalizacije globalnih logističkih lanacaRatko Zelenika
, 2007, recenzija, prikaz knjige, kritika
Opis: Temeljni cilj znanstvenog istraživanja ove doktorske disertacije jest učinak logističkih operatora u funkciji snižavanja ukupnih troškova globalnih logističkih lanaca. Da bi se cilj istraživanja i ostvario u odgovarajućim kombinacija korištene su brojne znanstvene metode od kojih se izdvajaju metoda anketiranja, metoda dinamičkog programiranja i metoda mješovitog cjelobrojnog programiranja. Zahvaljujući primijenjenoj znanstvenoj metodologiji mr.sc. Drago Pupavac uspješno je interpretirao dobivene rezultate dokazujući da modelski pristup odabira aktivnih sudionika logističkoga lanca logističkom operatoru daje uvid u sposobnosti potencijalne logističke mreže, opisuje sposobnosti pojedinih izvršitelja u logističkoj mreži, specificira logističke aktivnosti svakog pojedinog logističkog pothvata, daje informacije o troškovima izvršavanja specificiranih logističkih aktivnosti, daje neograničene mogućnosti procjene promjene strukture logističkog lanca, te dokazuje da je logistički operator stanju optimalizirati logističke lance i braniti ih od promjenjivosti i nepostojanosti potražnje.
Ključne besede: logistični operater, dinamična optimizacija, globalne logistične verige logistika, transport, promet
Objavljeno: 18.07.2017; Ogledov: 101; Prenosov: 4
Celotno besedilo (263,66 KB)
Mixed-integer nonlinear programming based optimal time scheduling of construction projects under nonconvex costsRok Cajzek
, Uroš Klanšek
, 2016, izvirni znanstveni članek
Opis: Optimal project scheduling under nonconvex time-cost relations represents a challenging problem in construction management. The nonconvex time-cost relations may appear in a construction project when several different duration options are available for its activities due to alternative technological processes enabled for their realization or wide accessibility of production resources. The source of nonconvexity of the project scheduling optimization problem can also be the project penalty- or bonus-duration relations arranged within the construction contract. The aim of this paper is to present the mixed-integer nonlinear programming (MINLP) based optimal time scheduling of construction projects under nonconvex costs. For this purpose, the MINLP model was developed and applied. A numerical example from literature and an example of construction project time-cost trade-off analysis under practical nonconvex penalty function are given in the paper to demonstrate advantages of MINLP optimization. The example from literature first presented the capability of the MINLP approach to obtain the optimal solution for difficult, highly combinatorial nonconvex discrete project scheduling problem. Thereupon, the following example revealed that the optimal project time-cost curve may take very nonuniform shape on account of discrete nature of activity direct cost options and nonconvex relation between project duration and total cost. In this way, the presented study intends to provide practitioners with new information from the field of optimization techniques for project scheduling as well as an alternative view on performance of total cost when project duration is changed.
Ključne besede: extreme environments, construction management, discrete optimization, mixed-integer nonlinear programming, nonconvex costs, time scheduling
Objavljeno: 12.07.2017; Ogledov: 90; Prenosov: 11
Celotno besedilo (807,33 KB)
Analysis of the influence of car-following input parameters on the modelled travelling timeIrena Ištoka Otković
, Tomaž Tollazzi
, Matjaž Šraml
, 2013, kratki znanstveni prispevek
Opis: The calibration process is a basic condition of traffic model application in local conditions. The choice of input parameters, which are used in calibration process, influences the success of the calibration process itself; therefore, the goal is to choose parameters with a larger influence on the modelling process. This paper offers a detailed analysis of car-following input parameters and their influence on the modelled travelling time. The experimental basis was a one-lane roundabout, and the tool used for traffic simulation was the VISSIM microsimulation traffic model. The results show that the car-following input parameters should be a part of the set of input parameters, which will enter the process of calibration. The examined car-following input parameters affect the capacity of intersections and results show that it is necessary to revise the range of input values of one of the observed car-following input parameters.
Ključne besede: car-following input parameters, input parameters for the process of calibration, VISSIM
Objavljeno: 11.07.2017; Ogledov: 95; Prenosov: 8
Celotno besedilo (680,10 KB)
Determinants of cruise passengers' expenditures in the port of callMaršenka Marksel
, Polona Tominc
, Stanislav Božičnik
, 2016, izvirni znanstveni članek
Opis: Cruise tourism generates different types of cruise consumption and related indirect, direct and induced expenditure effects, in homeports as well as in ports of call. Cruise passengers´ expenditures produce positive economic effects for destinations, from increasing the incomes and employment, to tax incomes, duties, etc. Therefore, it is no doubt that cruise stakeholders and local economies can benefit from increased cruise passenger consumption. To stimulate higher consumption and passengers´ satisfaction, it is necessary to design the supportive policy framework and build appropriate quality of products and services. Identifying influential variables of cruise passengers´ expenditures in this sense enables the design of appropriate policies and measures. In the current research, based on a survey of 357 cruise passengers, several variables included in a new theoretical model of the expenditures determinants, such as gender, nationality, frequency of cruising and frequency of visits, were found to be statistically significantly associated with cruise passengers´ expenditures. Several conclusions and suggestions to stimulate cruise passenger expenditures based on research findings are provided.
Ključne besede: cruise tourism, consumption, behavioural intentions, tourism, maritime transport
Objavljeno: 04.07.2017; Ogledov: 66; Prenosov: 3
Celotno besedilo (773,65 KB)
Isospin violating decays of positive parity Bs mesons in HMχPTSvjetlana Fajfer
, Anita Prapotnik Brdnik
, 2016, izvirni znanstveni članek
Opis: Recent lattice QCD results suggest that the masses of the first two positive parity Bs mesons lie below the BK threshold, similar to the case of D∗s0(2317)+ and Ds1(2460)+ mesons. The mass spectrum of Bs mesons seems to follow the pattern of a Ds mass spectrum. As in the case of charmed mesons, the structure of positive parity Bs mesons is very intriguing. To shed more light on this issue, we investigate the strong isospin violating decays B∗0s0→B0sπ0, B0s1→B∗0sπ0, and B0s1→B0sππ within heavy meson chiral perturbation theory. The two-body decay amplitude arises at tree level and we show that the loop corrections give significant contributions. On the other hand, in the case of three-body decay B0s1→B0sππ the amplitude occurs only at loop level. We find that the decay widths for these decays are Γ(B0s1→B0sππ)∼10−3 keV, and Γ(B∗0s0→B0sπ0)≤55 keV, Γ(B0s1→B∗0sπ0)≤50 keV. More precise knowledge of the coupling constant describing the interaction of positive and negative parity heavy mesons with light pseudo-scalar mesons would help to increase the accuracy of our calculation.
Ključne besede: physics, elementary particles, B mesons, decays
Objavljeno: 26.06.2017; Ogledov: 116; Prenosov: 2
Celotno besedilo (743,71 KB)
Open space evaluation methodology and three dimensional evaluation model as a base for sustainable development trackingMelita Rozman Cafuta
, 2015, izvirni znanstveni članek
Opis: Sustainable development, as a concept of controlled development, is a management characteristic. Adaptation to progress is important to achieve sustainability. The research focus here is on developing an evaluation methodology for determining the characteristics of urban open space. A method was designed for use in the comparative analysis of environmental perception evaluation between different time sequences. It allows us to compare results before and after spatial interventions or spatial development tracking over time. The newly-developed SEC model (suitable for everyone, environmentally-accepted, and cost-effective) was an essential element used in the research methodology. The model was designed using the systematic principle, the top–down approach, and the decomposition method. Three basic dimensions were divided into six factors. Factors were divided into eighteen indicators that are either quantitatively or qualitatively assessed. Indicators were divided into several aspects. An instrument (questionnaire) was developed to support the evaluation methodology of urban open space characteristics. Every aspect belongs to a question in the questionnaire. The applicability of the SEC model was demonstrated in two case studies. Evaluation took place during two different time sequences, once during the day-time and once during the night. Obtained results provide useful information of the current spatial situation needed for sustainable development strategy preparation.
Ključne besede: urbano okolje, vizualna percepcija, vizualno zaznavanje, vidno zaznavanje, metodologija vrednotenja, SEC model
Objavljeno: 22.06.2017; Ogledov: 130; Prenosov: 4
Celotno besedilo (2,65 MB)
On algebraic approach in quadratic systemsMatej Mencinger
, 2011, pregledni znanstveni članek
Opis: When considering friction or resistance, many physical processes are mathematically simulated by quadratic systems of ODEs or discrete quadratic dynamical systems. Probably the most important problem when such systems are applied in engineering is the stability of critical points and (non)chaotic dynamics. In this paper we consider homogeneous quadratic systems via the so-called Markus approach. We use the one-to-one correspondence between homogeneous quadratic dynamical systems and algebra which was originally introduced by Markus in (1960). We resume some connections between the dynamics of the quadratic systems and (algebraic) properties of the corresponding algebras. We consider some general connections and the influence of power-associativity in the corresponding quadratic system.
Ključne besede: quadratic systems, nonlinear systems
Objavljeno: 14.06.2017; Ogledov: 180; Prenosov: 3
Celotno besedilo (2,74 MB)
An application of the Sakai's theorem to the characterization of H*-algebrasBorut Zalar
, 1995, izvirni znanstveni članek
Opis: The well-known Sakai's theorem, which states that every derivation acting on a von Neumann algebra is inner, is used to obtain a new elegant proof of the Saworotnow's characterization theorem for associative ▫$H^\ast$▫-algebras via two-sided ▫$H^\ast$▫-algebras. This proof completely avoids structure theory.
Ključne besede: mathematics, functional analysis, ▫$H^\ast$▫-algebra, involution, automorphism, derivation, centralizer, von Neumann algebra
Objavljeno: 14.06.2017; Ogledov: 77; Prenosov: 3
Celotno besedilo (2,06 MB)