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Juvenile delinquency school failure and dropout in Portugal : drafting a picture in different voices
Ana Cardoso, Heloísa Perista, Paula Carrilho, Mário Jorge Silva, 2013, izvirni znanstveni članek

Opis: Purpose: The purpose of this article is to address and discuss the relationship between different school paths and self-reported young students’ behaviours and perceptions regarding violence and delinquency. Their views on prevention deserve particular attention. This is though a picture drafted in different voices, since young students’ opinions contrast with those of several other actors in the domain of juvenile delinquency. Design/Methods/Approach: This analysis is based on the YouPrev project findings in Portugal, generated by the different empirical data collection instruments employed, thus combining a quantitative and a qualitative approach. Gender differences as well as differences between urban and rural regions are highlighted whenever relevant. Findings: School failure and dropout is a structural problem in Portugal and some expert views anticipate a reversal in recent trends and a new rise of these phenomena as a result of the current crisis. The YouPrev school survey outcomes in Portugal confirm that young people with negative school integration have a higher life-time prevalence of self-reported delinquency. Among the 1,755 young students surveyed, 29.4% reported they had committed, over their life-time, at least one of the offences listed in the questionnaire. 156 of these students reported that they had committed a violent offence during the last twelve months. Among these, 46 may be described as frequent violent offenders. The concentration of risk factors among the frequent violent offenders shows that these are also victims of other forms of violence in the context where they live in. Young people share the idea that “what works” best in the prevention of juvenile delinquency is to improve their prospects to get a job and to provide them a good general education. Both in the rural and in the urban regions the relationship between young people and the family is seen as crucial either by experts or by the young boys and girls. Research Limitations / Implications: Self-reported delinquency surveys attempt to overcome insufficiencies of the official statistics – these surveys open the possibility to obtain more diverse information and to identify delinquent practices that are not registered. But one of the possible criticisms is that, in these kinds of studies, chronic and persistent delinquents are not represented. In this particular analysis, information is missing for those students who skip school and those whose parents, for different reasons, did not give consent to their participation in the survey. The conduction of expert face-to-face interviews complemented the prospective information collected by the Delphi study, compensating and enriching the relative low number of responses to the survey. Practical Implications: The outcomes promote the awareness-raising on juvenile delinquency and prevention strategies among different actors: experts, schools, and young students. These can also be used as training material for professionals, working in social services and police forces, in particular. Originality/Value: This study contributes to the body of knowledge on the practices and views within the domain of juvenile delinquency and violence. This is a research topic insufficiently explored in Portugal, at least in a comprehensive way, either in terms of subjects or territorial coverage. It also adds to existing research with crossed views, based on a multi-method approach, on the interplay between school failure and dropout and juvenile delinquency and prevention.
Ključne besede: juvenile delinquency, violence, prevention, school failure, Portugal
Objavljeno v DKUM: 20.04.2020; Ogledov: 535; Prenosov: 19
.pdf Celotno besedilo (614,36 KB)
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Effect of particle roundness and morphology on the shear failure mechanism of granular soil under strip footing
Babak Karimi Ghalehjough, Suat Akbulut, Semet Çelik, 2018, izvirni znanstveni članek

Opis: This study investigates the effect of particles roundness and morphology on the shear failure mechanism of soil. A strip footing was modeled under laboratory conditions. Calcareous soil was tested with three roundness classes: angular, rounded and well-rounded shapes with sizes of 0.30 mm to 4.75 mm. These were divided into six different groups at three relative densities of 30%, 50% and 70%. A series of photographs was taken during the tests and analyzed using the particle image velocimetry (PIV) method to understand the soil-deformation mechanism. The results showed that increasing the sample sizes increased the affected area of the soil. At the same time, increasing the relative density caused a punching failure mechanism that went towards the general failure. The shear failure mechanism of the soil changed from general toward punching shear failure with increasing particle roundness. This effect was larger with the smaller materials. Underneath the affected layers of soil, the angular samples were deeper than the rounded and well-rounded samples. The affected depth in the angular soil was approximately 1.5B in the smallest size group. This was more than 3B and near 4B in the largest size group. Both the sides and the underlying soil layers should be considered on angular soils. The area under the footing becomes more important than the side parts after increasing the roundness of the particles.
Ključne besede: particle roundness, morphology of particles, shear failure mechanism, strip footing, PIV method, ultimate bearing capacity
Objavljeno v DKUM: 11.10.2018; Ogledov: 1028; Prenosov: 382
.pdf Celotno besedilo (701,47 KB)
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A new method for testing the anti-permeability strength of clay failure under a high water pressure
Fu-wei Jiang, Ming-tang Lei, Xiao-zhen Jiang, 2015, izvirni znanstveni članek

Opis: It is difficult to judge the failure of clay seepage under a high water pressure.This paper presents a new method to assess clay failure based on the anti-permeability strength, which is the critical water pressure to destroy the clay. An experiment is designed to test the value that avoids the problem of the time-consuming, traditional method to test clay seepage deformation. The experimental system and the process of testing are introduced in this paper. With a self-designed experimental system and method, 18 groups of sample were tested. The results show that the clay thickness and the seepage paths influence the anti-permeability strength. It also indicates that water infiltrates into the clay under the condition that its pressure exceeds a minimum value (P0).
Ključne besede: clay failure, seepage deformation, anti-permeability strength, high water pressure
Objavljeno v DKUM: 15.06.2018; Ogledov: 818; Prenosov: 43
.pdf Celotno besedilo (249,24 KB)
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Relationship between the compressive and tensile strengths of lime-treated clay containing coconut fibres
Vivi Anggraini, Bujang Huat, Afshin Asadi, Haslinda Nahazanan, 2015, izvirni znanstveni članek

Opis: The effects of coconut fibre on the mechanical characteristics of lime-treated clay are investigated in this study. The lime-treated clay specimens were prepared with a variety of coconut-fibre contents, i.e., 0.5%, 1%, 1.5% and 2%, in terms of the weight of dry soil. The stabilized specimens were tested at 7, 28 and 90 days after the treatment in order to observe the evolution of the mechanical resistance with time. The results of the unconfined compressive strength tests were used to determine the relationships between the compressive strengths and the indirect tensile strengths of the stabilized soil. Furthermore, the optimum percentage of coconut fibre mixed in the soil/lime mixtures was 1% of the dry mass and reinforcement at 90 days increases the peak compressive strength and the indirect tensile strength. Coconut-fibre inclusion changes the brittle behaviour of the lime-treated clay soil to give it a more ductile character.
Ključne besede: coconut fibre, lime, compressive strength, indirect tensile strength, clay soil, failure characteristics
Objavljeno v DKUM: 14.06.2018; Ogledov: 686; Prenosov: 37
.pdf Celotno besedilo (755,61 KB)
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The limit values and the distribution of three-dimensional passive earth pressures
Stanislav Škrabl, 2008, izvirni znanstveni članek

Opis: This paper presents a novel approach to the determination of the critical distribution and limit values of three-dimensional passive soil pressures acting on flexible walls following the upper-bound method within the framework of the limit-analysis theory. The method of limit analysis with a set of three-dimensional kinematically admissible hyperbolic translational failure mechanisms is used to determine the critical distribution of the passive pressures along the retaining structurećs height. The intensity of thepassive pressures is gradually determined with the mentioned translational failure mechanisms in the top-down direction. Thus, the critical distribution,the trust point and the resultant of the passive pressures that can be activated at the limit state for the chosen kinematic model are obtained. The results of the analyses show that the total sum of passive pressures, considering the critical distribution, is lower than the comparable values published in the literature. Furthermore, the trust point of the passive pressure resultant is independent of the friction between the retaining structures and the soil.
Ključne besede: limit analysis, earth pressure, passive pressure, failure surface, soil-structure interaction
Objavljeno v DKUM: 05.06.2018; Ogledov: 604; Prenosov: 52
.pdf Celotno besedilo (331,84 KB)
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Determination of passive earth pressure using three-dimensional failure mechanism
Helena Vrecl-Kojc, Stanislav Škrabl, 2007, izvirni znanstveni članek

Opis: This paper presents a modified three-dimensional (3D) failure mechanism for determining the 3D passive earth pressure coefficient using the upper bound theorem within the framework of the limit analysis theory. The translational kinematically admissible failure mechanism generalized with a depth of h = 1.0 is considered in the analysis. The mechanism geometry presents a volume of rigid blocks composed of the central body and two lateral rigid bodies, which are connected by a common velocity field. The front surface of the central body interacts with the retaining wall, while the upper surface can be loaded by surcharge loading. The lateral body segments represent four- and three-sided polygons in the cross section of the central body; therefore, they define the polygonal failure surface of the central part. At the outer side, each segment of the lateral body is bounded by infinitesimally spaced rigid half-cones that describe the envelope of a family of half-cones. The numerical results of 3D passive earth pressure limit values are presented by non-dimensional coefficients of passive earth pressure influenced by the soil weight Kpg and a coefficient of passive earth pressure influenced by the surcharge Kpq. This research was intended to improve the lowest values obtained until now using the limit analysis theory. The results are presentedin a graphical form depending on the geometrical parameters and soil properties. A brief description of two world-recognized failure mechanisms based on the limit analysis approach, and the comparison of three failure mechanism results are also presented.
Ključne besede: soil mechanics, passive earth pressure, upper bound theorem, optimization, three-dimensional failure mechanism
Objavljeno v DKUM: 18.05.2018; Ogledov: 722; Prenosov: 46
.pdf Celotno besedilo (504,97 KB)
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Validation test plan for relays in avtomotive industry
Urban Cotič, 2017, magistrsko delo

Opis: The master’s thesis discusses different approaches how to assure the quality and reliability of high voltage contactors in automotive industry. In the beginning, the history of the development is described, followed by basic knowledge about materials and magnetic theory used in relays. The main part of the thesis is tests defying to qualify the relays for usage in automotive industry. There are different tests, divided in different groups. Second important part is reliability prediction according to standards used in this area of business. Reliability prediction and calculation of failure rate on different contactors are described in last chapters. Calculation also included influence of different factors on life span of the parts. In conclusion, the results are commented and proposal for development is given based on results of the research.
Ključne besede: Automotive industry, high voltage contactors, testing, reliability, failure rate
Objavljeno v DKUM: 07.02.2018; Ogledov: 1053; Prenosov: 96
.pdf Celotno besedilo (1,89 MB)

Opportunities for the applications of FMEA Model in logistics processes in Bulgarian enterprises
Maria Vodenicharova, 2017, izvirni znanstveni članek

Opis: The article explores the use of FMEA method in the logistics processes in manufacturing plants in Bulgaria. The surveyed enterprises have a system ISO 9001 and apply different methods of analysis and assessment of logistics processes. The purpose of this study is to present a model for improving the reliability of logistics processes through the FMEA (Failure Mode and Effect Analysis) method. An inquiry among 14 organizations in the implementation of FMEA was conducted. The results show that FMEA is not used for assessment in logistics processes and provides useful insights for decision-making to improve the reliability of supply. A framework based on the survey is presented for determining the reliability of logistics processes in manufacturing plants. The study demonstrates the applicability of the method in logistics processes and the role FMEA can play in assessing logistics processes.
Ključne besede: failure mode effects and analysis (FMEA), logistics process, quality
Objavljeno v DKUM: 17.11.2017; Ogledov: 1334; Prenosov: 401
.pdf Celotno besedilo (247,27 KB)
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Analytical and numerical factor of safety (uls) calculations on reinforced embankments
Tadej Vidnar, 2017, magistrsko delo

Opis: This thesis deals with factor of safety calculations on geogrid reinforced embankments carried out by commonly used limit equilibrium (LEM) and finite element methods (FEM). The study utilize LEM based software SLIDE and FEM based software PHASE2. The main difference between these two approaches is that the LEM methods are based on the static of equilibrium whereas FEM methods utilise the stress strain relationship. Unlike to LEM, numerical analysis also computes displacements. For practical example of a geogrid reinforced embankment the factor of safeta (FoS) is calculated. Reinforced soil structures are nowadays utilized for a lot of civil engineering applications. Traditionally, the design of geogrid reinforced soil is performed using analytical methods (LEM). Unfortunately, these methods missing the fundamental physics of stress-strain relationship and are therefore not able to compute a realistic stress distribution. In first step of the analysis the FoS is carried out with analytical approach. The most rigorous LEM methods, Bishop’s, Spencer’s and Morgenstern-Price are selected and the FoS for circular and polygonal slip surface is calculated. In second step of the analysis the FoS is carried out with numerical approach. Shear strength reduction (SSR) procedure was performed to determine the critical strength reduction factor (SRF) which represents the FoS of slope.
Ključne besede: civil engineering, finite element method (FEM), limit equilibrium method (LEM), embankments, slope stability, bearing capacity failure, geosynthetics, geogrids, shear strains
Objavljeno v DKUM: 27.09.2017; Ogledov: 882; Prenosov: 165
.pdf Celotno besedilo (17,05 MB)

Deformation and energy parameters of fracture of steel of the main gas pipeline
P. O. Maruščak, Sergey Panin, Ulyana Polyvana, Tomaž Vuherer, Anna Guzanová, Janette Brezinová, 2015, izvirni znanstveni članek

Opis: By example of steel 17G1S, the regularities in the impact fracture of Charpy specimens at normal and low temperatures are described. The relationship between the energy parameters of fracture (impact toughness) and the deformation response of the material (the height of shear lips) of the specimens from the pipe steel is established. The micromechanisms of impact fracture of the material are described. At 20 °C and –30 °C, focal splitting of the material was observed on the fracture surface of specimens; at –60 °C, the material failed in a brittle manner by the mechanism of cleavage.
Ključne besede: impact toughness, main gas pipeline, failure analysis
Objavljeno v DKUM: 08.08.2017; Ogledov: 784; Prenosov: 342
.pdf Celotno besedilo (2,03 MB)
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