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Abstract: Robust, automated mesh generation on arbitrary weld joint geometries, using finite element method (FEM) is a problematic task. It was previously discovered, that an arbitrary weld joint geometry can be parameterized inside a CAD environment [1], however when it comes to domain discretization and boundary conditions assignment, the parameterized approach becomes too demanding inside FEM. This results in long FEM model preparation times and sometimes in problems with the parametric model itself, which leads to a need for an additional numerical method - boundary element method (BEM), which overcomes this issue and is beneficial in this case. BEM is a numerical method, that in addition to other applications finds a use in the elasto-mechanic problems, where the only concern is the boundary of the considered geometric domain. Since notch stress calculations of weld joints fall into this category, their calculation can be carried out with it. Since there is not much available information on whether or not such calculations are a suitable alternative for the currently used FEM, this thesis had to be confirmed through a structured and step by step procedure. First, a notch mesh quality study has been made, then other entities followed. It was discovered that BEM is applicable to the problem and capable of calculating results with sufficient quality. Furthermore, the parameter driven approach and automated calculation provide for additional advantageous potentials.
Keywords: weld joint, boundary element method, finite element method, spatial discretization, notch stress
Published in DKUM: 02.11.2022; Views: 129; Downloads: 0
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Abstract: Purpose: The purpose of this paper is to review the decade of Slovenian police officer’s experiences with international peacekeeping operations. The main goal of police officers, involved in these missions, is to prevent conflicts between opposite sites, to implement basic agreements, protect humanitarian missions and reinforce policing operations in the conflict area. The purpose of the paper is to acknowledge the lessons learned while planning and implementing further cooperation of Slovenian police officers in peacekeeping (police) operations. The main purpose of the paper is to analyze the consequences of deployment to peacekeeping missions for police officers as well as their family members (partners and children) by analyzing the psychodynamic processes related to the involvement in peacekeeping missions. Design/Methods/Approach: The paper is based on the review of literature. The empirical part of the paper presents the results of the research on a small sample of police officers (n = 36) and their family members (n = 25 partners + 35 children). Findings: Police peacekeepers should be well prepared for different stress situations; they are exposed to various stress factors before, during, and after serving in a mission. That is why training and reintegration programmes are of great importance. We establish that respondents assess that deployment to a peacekeeping mission has a positive and negative impact on the relationships between family members. As many as ¾ of mission members believe deployment can have a positive impact above all in the sense of strengthening the emotional ties between partners, increased mutual trust and strengthening of the partnership. For them, deployment to a peacekeeping mission is a challenge and personal experience, which can change the way they see the world. 2/3 of partners state similar positive impacts and they also believe that there is more trust between the partners after the experience with the peacekeeping mission, they treasure their time together and thus represent bigger support for each other in difficult times. As the most common problem, respondents perceived marital problems and the occurrence of negative feelings among family members (anger, avoidance, judgment ...). A large share of respondents stressed problems with children. 43.8% of respondents also named depression as a problem. Research limitations/implications: The findings are limited to the Slovenian police and their police officer’s experiences, serving in various police peacekeeping missions and their family members. Practical implications: Based on lessons learned this paper complements the results of different surveys of the researched topic. The results cannot be completely generalized, although some findings could also be useful to similar police organizations in Europe. Originality/Value: This paper addresses and explores different small scale surveys, conducted on sampled Slovenian police officers who served in peacekeeping missions and their family members. Findings could be of interest for the general as well as expert audience.
Keywords: police, police officer’s family, peacekeeping missions, Slovenia, stress, training and reintegration programmes, SE Europe
Published in DKUM: 05.05.2020; Views: 804; Downloads: 42
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Abstract: Epigenetics is a study of heritable changes in gene expression and function that do not change the DNA sequence itself. One of the commonly described epigenetic modifications is DNA methylation where a methyl group is added to the fifth carbon of the cytosine (Lim & Maher, 2010). This may lead to gene silencing, regulation of gene expression and allows for plant plasticity to changing environment (Verhoeven et al., 2010). Epigenetic variation is often studied in species with asexual reproduction, due to the absence of genetic variation between individuals and because clonal species do not go through a germline and meiosis between generations which epigenetic resetting occurs. Lemna minor, also known as common duckweed, is the smallest flowering macrophyte that consist of modified leaf structures (fronds) and one hanging root. It is known for its rapid asexual reproduction (Ziegler et al., 2015). Daughter fronds are genetically identical to the mother plant and are produced without involvement of male or female germlines. Fast asexual reproduction makes Lemna minor a perfect candidate to study epigenetic effects of de novo gene regulatory evolution. The aim of this project is to screen divergence of environmentally-induced DNA methylation between different experimental treatments over multiple generations. The aim of this project is to screen divergence of temperature-induced DNA methylation between different experimental treatments over multiple generations. Results show that, temperature stress has a strong influence on L. minor growth and reproduction, and induces significant change in the DNA methylation in the CG and CHG methylation context. Temperature-induced DNA methylation was inherited over multiple clonal generation of L. minor in the CHG contexts, although since we did not detect any performance difference the functional consequences of this DNA methylation are unclear. This study contributes to the knowledge of environmentally-induced DNA methylation changes, which is essential regarding the increasing frequency of global climate changes.
Keywords: DNA methylation, duckweed, epigenetics, epiGBS, abiotic stress, transgenerational inheritance, asexual reproduction
Published in DKUM: 29.01.2019; Views: 1129; Downloads: 115
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Abstract: This paper reports a simplified analytical solution for estimating the soil stress distribution due to pile dependence on the pile dimensions. The exponentially increasing ultimate skin friction along the pile shaft is derived by means of an equilibrium analysis of the soil element around the pile. The soil stress distribution due to the exponentially increasing skin friction and uniformly distributed end bearing of the piles is proposed. The estimated soil stresses are compared using the original Geddes solution, which validates the derivation and formulae obtained.
Keywords: analytical solution, soil stress distribution, skin friction, end bearing
Published in DKUM: 18.06.2018; Views: 1238; Downloads: 70
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Abstract: The plastic critical depth or the conventional tension crack depth has a considerable effect on the active lateral earth pressure in cohesive soils. In this paper the depth for c-ϕ soils has been evaluated in the seismic case using the stress-characteristics or slip-line method. The plastic critical depth was calculated on the basis of the theory of the stress-characteristics method and by considering the horizontal and vertical pseudo-static earthquake coefficients. The proposed solution considers the line of discontinuity in the stress-characteristics network. The earth slope, wall slope, cohesion and friction angle of the soil and the adhesion and the friction angle of the soil-wall interface were considered in the analysis as well. The results show that the plastic critical depths of this study are smaller than those of the other methods and are closer to the modified Mononobe-Okabe method. The effects of the wall and the backfill geometry, the mechanical properties of the soil and the pseudo-static coefficients were studied.
Keywords: plastic critical depth, stress characteristics, active lateral earth pressure, seismic
Published in DKUM: 15.06.2018; Views: 985; Downloads: 71
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