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New computational models for better predictions of the soil-compression index
Ahmet Demir, 2015, izvirni znanstveni članek

Opis: The compression index is one of the important soil parameters that are essential for geotechnical designs. Because laboratory and in-situ tests for determining the compression index (Cc) value are laborious, time consuming and costly, empirical formulas based on soil parameters are commonly used. Over the years a number of empirical formulas have been proposed to relate the compressibility to other soil parameters, such as the natural water content, the liquid limit, the plasticity index, the specific gravity. These empirical formulas provide good results for a specific test set, but cannot accurately or reliably predict the compression index from various test sets. The other disadvantage is that they tend to use a single parameter to estimate the compression index (Cc), even though Cc exhibits spatial characteristics depending on several soil parameters. This study presents the potential for Genetic Expression Programming (GEP) and the Adaptive Neuro-Fuzzy (ANFIS) computing paradigm to predict the compression index from soil parameters such as the natural water content, the liquid limit, the plastic index, the specific gravity and the void ratio. A total of 299 data sets collected from the literature were used to develop the models. The performance of the models was comprehensively evaluated using several statistical verification tools. The predicted results showed that the GEP and ANFIS models provided fairly promising approaches to the prediction of the compression index of soils and could provide a better performance than the empirical formulas.
Ključne besede: compression index, statistical analysis, genetic expression programming, adaptive neuro-fuzzy, empirical equations
Objavljeno v DKUM: 14.06.2018; Ogledov: 1295; Prenosov: 76
.pdf Celotno besedilo (274,65 KB)
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The anchored pile wall optimization using NLP approach
Helena Vrecl-Kojc, 2005, izvirni znanstveni članek

Opis: The type of a retaining structure as well as the structure configuration mainly depends on geological conditions. If geological, urban and other data allow an alternative, the costs should also be considered as an important factor. In geotechnical practise, pile walls are especially used in excavations, in the erection of traffic facilities and in the sanitation of landslides. This paper is aimed at presenting economical differences between cantilever and anchoring pile walls and the impact of different parameters on costs. The optimization method, which uses mathematical programming, gives an optimal solution to geometry, self-manufacturing costs, and other characteristics of the structure in a uniform optimization process. This paper presents the optimization process using the nonlinear programming (NLP) approach for the anchored pile wall. The application presented only serves to confirm the effectiveness of the proposed optimization method. Therefore, the retaining structure is situated in homogeneous non-cohesive soil at three different soil friction angles of 35°, 30° and 25°. The generalized analytical method, the USA method, which was first introduced by Bowles [3], isused in the application. The analysis of the results shows the impact of parameters, the main controlling factors, configuration geometry and savings. The optimal results allowed from 18 up to 47 per cent savings compared to the cantilever pile wall depending on ground and structure input data and the excavation depth.
Ključne besede: civil engineering, optimum design, retaining structures, USA analytical method, nonlinear programming
Objavljeno v DKUM: 16.05.2018; Ogledov: 1226; Prenosov: 64
.pdf Celotno besedilo (216,45 KB)
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Organization in finance prepared by stohastic differential equations with additive and nonlinear models and continuous optimization
Pakize Taylan, Gerhard-Wilhelm Weber, 2008, izvirni znanstveni članek

Opis: A central element in organization of financal means by a person, a company or societal group consists in the constitution, analysis and optimization of portfolios. This requests the time-depending modeling of processes. Likewise many processes in nature, technology and economy, financial processes suffer from stochastic fluctuations. Therefore, we consider stochastic differential equations (Kloeden, Platen and Schurz, 1994) since in reality, especially, in the financial sector, many processes are affected with noise. As a drawback, these equations are hard to represent by a computer and hard to resolve. In our paper, we express them in simplified manner of approximation by both a discretization and additive models based on splines. Our parameter estimation refers to the linearly involved spline coefficients as prepared in (Taylan and Weber, 2007) and the partially nonlinearly involved probabilistic parameters. We construct a penalized residual sum of square for this model and face occuring nonlinearities by Gauss-Newton's and Levenberg-Marquardt's method on determining the iteration step. We also investigate when the related minimization program can be written as a Tikhonov regularization problem (sometimes called ridge regression), and we treat it using continuous optimization techniques. In particular, we prepare access to the elegant framework of conic quadratic programming. These convex optimation problems are very well-structured, herewith resembling linear programs and, hence, permitting the use of interior point methods (Nesterov and Nemirovskii, 1993).
Ključne besede: stochastic differential equations, regression, statistical learning, parameter estimation, splines, Gauss-Newton method, Levenberg-Marquardt's method, smoothing, stability, penalty methods, Tikhonov regularization, continuous optimization, conic quadratic programming
Objavljeno v DKUM: 10.01.2018; Ogledov: 1245; Prenosov: 137
.pdf Celotno besedilo (364,34 KB)
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Career planning as a building block of personal excellence
Marija Turnšek Mikačić, Marija Ovsenik, 2013, izvirni znanstveni članek

Opis: The narrow field of research here is the development of a model for the building of personal excellence using a career plan that is empirically tested and confirmed, both qualitatively and quantitatively. The purpose of this study relates to the writing of a career plan, for the determination of the factors that influence the feeling of personal excellence of participants in career planning education, in relation to other participants who are not. The qualitative analysis consists of basic experience data that was collected during the education process, through 20 essays, and the paradigmatic model, with the final theory defined, and based on this, a questionnaire was created. The quantitative analysis involved a total of 547 participants. For the statistical analyses of the data, bivariate analysis was used to assess the linear connection of individual pairs of variables. The search for differences between the two groups used t-tests for independent samples. Factor analysis was used to determine whether the relations among the examined variables can be explained with a smaller number of indirectly examined variables. The final model consists of three elements: (1) relation with career; (2) self-esteem; and (3) perception of personal excellence. Management can use the results of this study for management decisions. The increased success of every individual organisation benefits the whole of society. This study represents an original contribution and offers a new approach that is based on the paradigm of the understanding of a career and the importance of its planning as a motive for excellence.
Ključne besede: career planning, personal excellence, career break, qualitative analyses, quantitative analyses, neurolinguistic programming
Objavljeno v DKUM: 29.11.2017; Ogledov: 1347; Prenosov: 341
.pdf Celotno besedilo (435,85 KB)
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The effects of career planning education
Marija Turnšek Mikačić, 2015, izvirni znanstveni članek

Opis: Research Question (RQ): We employed a qualitative approach to study the effects of career planning education, perceiving it as an effective way to gain a deeper understanding of introductorily-organised career education. Purpose: We researched important areas to formulate a questionnaire for quantitative analysis. Method: We used a qualitative research approach in order to develop a theoretical framework for the exploration, interpretation and identification of the impact of education on career plans, on the changing attitudes towards careers, the raising of self-esteem and perception of personal growth. We used Neuro-linguistic programming as a tool to develop and achieve personal excellence within the career planning. Results: We constructed a paradigmatic model and developed the final theory. By means of qualitative analysis, we identified the elements of design criteria for the construction of the questionnaire; we measured the effects of education on career plans. Organization: The findings of the research will prove useful in personal management and career management in the process of planning and organizing the promotion of individuals within the organizations in accordance with the needs of those organizations. Originality: A career plan as a building block of personal growth, based on the model of career education with the in-built elements and tools of NLP, has been confirmed by the most recent studies in neuroscience. This represents a novelty, and, therefore, this study offers a genuine contribution, and is an indicator of contemporary knowledge, based on the results of the research. Limitations/Future Research: The model of career education and the results of this study open new directions for further research of the influence of career planning on the organisation of companies and their success, which is the phase of the study which was not carried out.
Ključne besede: career planning, qualitative analysis, neuro-linguistic programming, personal excellence
Objavljeno v DKUM: 02.08.2017; Ogledov: 1189; Prenosov: 103
.pdf Celotno besedilo (636,67 KB)
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Probabilistic behaviour of joints on joint forces in mechanisms
Boštjan Harl, Nenad Gubeljak, Marko Kegl, 2015, izvirni znanstveni članek

Opis: This paper discusses the influence of the clearance in joints on the joint reaction forces in mechanisms. By using mathematical programming, the optimal parameters of kinematic chains can be efficiently obtained by using the deterministic approach. However, the situation becomes more sophisticated if random effects of tolerances of the arm lengths and the random pin positions have to be considered. In this work the influence of clearances on joint forces is calculated by using the Taylor approximation and the Monte Carlo method. The implementation of the model is illustrated with two examples. The first example considers a closed loop chain, representing a four-bar mechanism being an actual part of a hydraulic support, employed in mining industry. The second example considers joint reaction forces of car wiper mechanism.
Ključne besede: joint forces, kinematic chain, mathematical programming, stochastic model
Objavljeno v DKUM: 12.07.2017; Ogledov: 888; Prenosov: 423
.pdf Celotno besedilo (1,11 MB)
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Mixed-integer nonlinear programming based optimal time scheduling of construction projects under nonconvex costs
Rok 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 v DKUM: 12.07.2017; Ogledov: 1415; Prenosov: 401
.pdf Celotno besedilo (807,33 KB)
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SimpleConcepts: a lightweight extension to C++ to support constraints on generic types
Reed Milewicz, Marjan Mernik, Peter Pirkelbauer, 2014, izvirni znanstveni članek

Opis: Generic programming plays an essential role in C++ software through the use of templates. However, both the creation and use of template libraries is hindered by the fact that the language does not allow programmers to specify constraints on generic types. To date, no proposal to update the language to provide concepts has survived the committee process. Until that time comes, as a form of early support, this paper introduces SimpleConcepts, an extension to C++11 that provides support for concepts, sets of constraints on generic types. SimpleConcepts features are parsed according to an island grammar and source-to-source translation is used to lower concepts to pure C++11 code.
Ključne besede: generic programming, C++ templates, C++ concepts
Objavljeno v DKUM: 06.07.2017; Ogledov: 1087; Prenosov: 366
.pdf Celotno besedilo (299,20 KB)
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Triangulation of methods of career education
Marija Turnšek Mikačić, 2015, izvirni znanstveni članek

Opis: This paper is an overview of the current research in the field of career education and career planning. Presented results constitute a model based on the insight into different theories and empirical studies about career planning as a building block of personal excellence. We defined credibility, transferability and reliability of the research by means of triangulation. As sources of data of triangulation we included essays of participants of education and questionnaires. Qualitative analysis represented the framework for the construction of the paradigmatic model and the formulation of the final theory. We formulated a questionnaire on the basis of our own experiences in the area of the education of individuals. The quantitative analysis, based on the results of the interviews, confirms the following three hypotheses: The individuals who elaborated a personal career plan and acted accordingly, changed their attitudes towards their careers and took control over their lives; in addition, they achieved a high level of self-esteem and self-confidence, in tandem with the perception of personal excellence, in contrast to the individuals who did not participate in career education and did not elaborate a career plan. We used the tools of NLP (neurolinguistic programming) as an additional technique at learning.
Ključne besede: triangulation, career planning, excellence, neurolinguistic programming
Objavljeno v DKUM: 06.07.2017; Ogledov: 1045; Prenosov: 334
.pdf Celotno besedilo (858,33 KB)
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Dynamic optimization in supply chains
Drago Pupavac, Jasmina Pašagić Škrinjar, Ratko Zelenika, 2007, izvirni znanstveni članek

Opis: Production and stock optimization in supply chains is a complex problem because it determines the optimum quantity production in time. Due to their multileveld nature, those problems are mostly solved by different methods and models of dynamic programming. The problem discussed in this paper refers to the determination of optimum quantity of production and stocks within the supply chain in a certain period of time, as well as in each sub-interval of a period, but with the condition that the production and stock expenditure remains minimal and that the predetermined demand in every sub-interval and throughout the entire observation period remains satisfied.
Ključne besede: transportation, logistics, transportation networks, supply chains, optimization, dynamic programming, traffic
Objavljeno v DKUM: 02.06.2017; Ogledov: 1294; Prenosov: 168
.pdf Celotno besedilo (1,78 MB)
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