Search results for "kl"
showing 10 items of 5772 documents
Stability analysis of clay brick masonry columns: numerical aspects and modelling strategies
2014
Stability analysis of masonry piers and columns is one of the most frequently treated subjects in the field of structural engineering. This attention is probably due to the challenge to solving the problem including different effects, which play an important role in evaluating the response of eccentrically-loaded columns. In this connection, accurate stability analysis of masonry piers and columns has to take into account the non-linear stress–strain law of masonry in compression, the limited tensile strength, the induced slenderness due to crack formation and geometrical non-linearity. Different theoretical models and numerical approaches were developed in the past to analyze the combined …
Buckling and Postbuckling of Stiffened Composite Panels with Cracks and Delaminations by Ritz Approach
2017
A Ritz approach for the analysis of buckling and post-buckling of stiffened composite panels with through-the-thickness cracks and/or delaminations is presented. The structure is modeled as the assembly of plate elements whose behavior is described by the First-order Shear Deformation Theory and von Karman’s geometric nonlinearities. Penalty techniques ensure continuity along the edges of contiguous plate elements and the enforcement of the restraints on the external boundaries. They are also used to avoid interpenetration problems. General symmetric and unsymmetric stacking sequences are considered. A computer code has been developed and used to validate the proposed method, comparing the …
Hand-Held texting is less distracting than texting with the phone in a holder: anyway, don't do it
2015
We studied the effects of texting while driving and the effects of mobile phone position (hand-held, holder) on drivers' lane-keeping performance, experienced workload, and in-car glance durations in a motion-platform driving simulator with 24 participants. Overall, we found the known negative effects of texting on lane-keeping performance, workload, and visual attention on road, suggesting that texting on the road in any manner is not risk-free. As a novel finding, we found that hand-held texting led to fewer lane-keeping errors and shorter total glance times off road compared to texting with the phone in a holder. We suggest the explanation is that the drivers had considerably more experi…
Analysis of Spatial Disparities by a Structural Equations Model
2008
This paper presents a new analytical framework for assessing spatial disparities among countries. It takes for granted that the analysis of a country’s performance cannot be limited solely to either economic or social factors. The aim of the paper is to combine relevant economic and non-economic (mainly social) aspects of a country’s performance in an integrated logical framework. Based on this idea, a structural simultaneous equation model will be presented and estimated in order to explore the direction of the causal relationship between the economic and the non-economic aspects of a country’s performance. Furthermore, an exploration of the trajectory that each country has registered over…
Vides aizsardzības kluba darbība 1987-1989
2021
Maģistra darba mērķis ir raksturot Vides Aizsardzības kluba laika periodā no 1987.–1989. gadam un izvērtēt organizācijas nozīmi Latvijas atmodas procesos. Aplūkoto laika periodu raksturo plašas politiskās izmaņas PSRS, kuru rezultāta sākas plašāka sabiedrības iesaiste politiskajos procesos. Pētījumā tiek sniegts ieskats organizācijas priekšvēsturē un izveidē, tās galvenajos darbības virzienos, problēmjautājumos, kuru risināšanā organizācija iesaistījās visplašāk, kā arī iemeslos, kādēļ 1989. gadā klubs nolēma kļūt par apolitisku organizāciju. Maģistra darbā izmantoti Latvijas valsts arhīvā un Zaļās Atmodas muzejā pieejamie materiāli par VAK darbību, tostarp organizācijas dibināšanas materiā…
Mass loading, distribution, and removal of antibiotics and antiretroviral drugs in selected wastewater treatment plants in Kenya.
2020
The discharge of active pharmaceutical ingredients (APIs) into the aquatic environment from wastewater effluents is a concern in many countries. Although many studies have been conducted to evaluate the APIs removal efficiencies and emissions to the environment in wastewater treatment plants (WWTPs), most of these studies considered the aqueous and sludge phases, disregarding the suspended particulate matter (SPM) phase. To try to understand the role of the SPM, the occurrence of five most common antibiotics and three antiretroviral drugs (ARVDs) commonly used in Kenya were investigated in this study. APIs partitioning and mass loading in influents and effluents of three different WWTPs: tr…
Assaying waterborne psychoactive drugs by the response to naturalistic predator cues in the stickleback (Gasterosteus aculeatus)
2020
Abstract Ecotoxicological effects of psychiatric drugs and drug metabolites released by the human population are of increasing environmental concern. In this study we evaluate behavioral responses to visual predator cues in wild caught three-spined stickleback (Gasterosteus aculeatus) after exposure to water-born citalopram, a widely prescribed selective serotonin reuptake inhibitor with antidepressant and anxiolytic effects. Fish were exposed to ecological relevant concentrations of citalopram (0.15 or 1.5 μg L−1) for 10 or 20 days. After drug exposure, individual fish were moved to a test arena where they were exposed to two naturalistic visual predator cues; a shadow from beneath, which …
Evaluation of the effects of titanium dioxide and aluminum oxide nanoparticles through tarsal contact exposure in the model insect Oncopeltus fasciat…
2019
Abstract Despite the increasing presence of metal nanoparticles in the biosphere as a consequence of their widespread use, knowledge about the impact of these nanoparticles on fauna, ecosystems and human health is far from completion. This is especially true for terrestrial invertebrates. Insects are environmentally exposed to nanoparticles by several ways, the ectopic contact being one of the most probable. The model insect Oncopeltus fasciatus, has been used in the present work for testing toxicity of nanoparticles present in a surface. Adverse effects of TiO2 nanoparticles and Al2O3 in nanoparticulated or bulk form on mortality, reproductive and embryonic developmental parameters have be…
Biomagnification of organohalogens in Atlantic salmon (Salmo salar) from its main prey species in three areas of the Baltic Sea
2012
Abstract Factors affecting the biomagnification of organohalogens in Baltic salmon from sprat, herring and three-spined stickleback were assessed in three feeding areas. Second sea-year salmon contained (in fresh weight of whole fish) 79–250 ng g− 1 polychlorinated biphenyls (ΣPCB), 0.9–2.7 pg g− 1 dibenzo-p-dioxins (ΣPCDD), 8–19 pg g− 1 dibenzofurans (ΣPCDF), 96–246 pg g− 1 coplanar PCBs, 2.4–3.6 ng g− 1 polybrominated diphenylethers (ΣPBDE), and 39–136 ng g− 1 Σindicator PCB6. The EU limits for WHO toxic equivalent concentrations in fish feed were already exceeded in one-year-old sprat and herring and were exceeded many-fold in older age groups. The differences in the biomagnification rat…
Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.
2017
Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …