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Abstract: 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.
Keywords: juvenile delinquency, violence, prevention, school failure, Portugal
Published in DKUM: 20.04.2020; Views: 688; Downloads: 24
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Abstract: 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).
Keywords: clay failure, seepage deformation, anti-permeability strength, high water pressure
Published in DKUM: 15.06.2018; Views: 1038; Downloads: 54
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Abstract: 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.
Keywords: limit analysis, earth pressure, passive pressure, failure surface, soil-structure interaction
Published in DKUM: 05.06.2018; Views: 790; Downloads: 62
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Abstract: 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.
Keywords: Automotive industry, high voltage contactors, testing, reliability, failure rate
Published in DKUM: 07.02.2018; Views: 1196; Downloads: 106
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Abstract: 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.
Keywords: civil engineering, finite element method (FEM), limit equilibrium method (LEM), embankments, slope stability, bearing capacity failure, geosynthetics, geogrids, shear strains
Published in DKUM: 27.09.2017; Views: 1090; Downloads: 177
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