Iskanje po katalogu digitalne knjižnice

Opis: In filling lines equipped with membrane separation devices in the form of filters energy, consumption is only one of the important working parameters, the other being sustainable filter performance in terms of separation efficiency. As the filling line is typically equipped with a valve, intermittent operation of the filter is an important form of its use. Whereas the overall energy consumption of the filtration process is governed by the continuous operation mode, the intermittent mode, characterised by opening/closing of the valve, contributes most to problems of filter failure, i.e., the breakthrough of filtered particles through the membrane. A model for determination of the energy intake of a microfiltration membrane during the opening and closing of a valve is presented in this work. The model is based on computational analysis of the pressure wave signals recorded during the opening/closing of the valve using Fourier transform, and expressed in a nondimensional filter area specific energy intake form. The model is applied to a case of constant pressure dead-end microfiltration with three filter types: a single membrane filter, a stacked filter and a pleated filter with filtration surface areas ranging from 17.7 cm2 to 2000 cm2. Both clean filters, as well as partially clogged filter cases are taken into account. Second order polynomial models of the energy intake are developed and evaluated based on extensive analysis of the experimental data. The analysis of energy intake results show that the largest energy intake was observed for the clean filter case. When membrane fouling occurs at the constant flow rate values it leads to larger energy intake, however, due to a decreasing specific flow rate during fouling these values do not exceed the clean filter case.
Ključne besede: membrane filtration, water hammer effect, membrane energy intake, filter clogging
Objavljeno v DKUM: 28.03.2025; Ogledov: 0; Prenosov: 1
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Opis: Soil contamination and the uptake of pollutants by food crops are widespread issues that vary greatly by region and are influenced by the mineral composition of the soil and local human activities. The Pannonian region, where agriculture has played a key role since Roman times, has been particularly impacted by the long-standing agricultural and industrial practices. While soil contamination with heavy metals is monitored by the Slovenian government, microplastic contamination and the uptake of pollutants into food crops have yet to become a regular component of monitoring efforts. In this study, we conducted a preliminary investigation into soil and crop contamination across the Pannonian region, focusing on identifying harmful contaminants and their potential uptake into food crops. Both soil and crop samples were analyzed for the presence of heavy metals with proven methods such as atomic absorption spectrometry (FASS), graphite furnace atomic absorption spectrometry (GF-AAS), atomic fluorescence spectrometry (AFS), and inductively coupled plasma–mass spectrometry (ICP-MS). Energy-dispersive X-ray spectroscopy (EDS) was found to be a potentially faster method of obtaining data on soil composition. Special attention was also given to the potential presence of microplastics in the region’s soils.
Ključne besede: soil contamination, Pannonia, soil, food crops, heavy metals, microplastics
Objavljeno v DKUM: 28.11.2024; Ogledov: 0; Prenosov: 2
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Opis: Microfiltration is an important process in the pharmaceutical industry. Filter selection and validation is a time-consuming and expensive process. Quality by design approach is important for product safety. The article covers the instrumentalization and process control of a laboratory-scale dead-end microfiltration layout. The layout is a downscale model of the actual production line, and the goal is filter validation and analysis of process parameters, which may influence filter operation. Filter size, fluid pressure, valve plunger speed, and timing issues were considered. The focus is on the identification of the most influential process parameters and their influence on the repeatability of pressure oscillations caused by valve opening. The goal was to find the worst-case scenario regarding pressure oscillations and, consequently, filter energy intake. The layout was designed as compact as possible to reduce pressure losses between the filter and valve. Valve-induced pressure oscillations proved to be prevailing over the water hammer effect. Several filters in sizes between 3.5 cm2 and 6900 cm2 were tested, and some recommendations were suggested for the reduction of energy intake of the filter and to improve the repeatability of the process.
Ključne besede: filtration, pressure oscillations, repeatability, processes, parameters
Objavljeno v DKUM: 01.02.2024; Ogledov: 425; Prenosov: 34
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Opis: Introduction: Poor adoption of electronic health records among healthcare workers can diminish their impact. Healthcare informatics solutions development should diligently acknowledge end-user needs.This study compares a user experience and perceived quality of the nursing process integration in two different applications for electronic documentation of the nursing care plan. Both applications were designed and tested in Slovenia. Methods: In the first phase, final year undergraduate nursing students were recruited (n=73) and randomly assigned into two groups. Each group used one of the applications for a duration of five hours. A survey among students was conducted. In the second phase, additional students were recruited (n=40) and invited to participate in qualitative analysis of the unfavourably rated application. Results: The modern, visually improved application was favourably rated by students in terms of all aspects of application usability. However, students reported a significant number of inadequacies regarding the nursing process methodology integration. On the contrary, the students using the poorly rated and visually outdated application reported no such concerns. Qualitative analysis of student reflections identified additional positive features of software design that were not detected in survey results analysis. Conclusion: This study showed that a user-centred approach can be used to compare diverse electronic solutions. Detected discrepancies in findings using qualitative and quantitative analysis show the importance of integrating diverse research approaches for adequate evaluation of software solutions. Furthermore, this study design promotes empowerment of healthcare workers to participate in the development and critical evaluations of software solutions.
Ključne besede: nursing process, information technology, documentation, user experience, quantitative/ qualitative approach
Objavljeno v DKUM: 12.07.2023; Ogledov: 494; Prenosov: 49
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Opis: V diplomskem delu je predstavljen trdnostni preračun priklopa gradbene prikolice GRAVIS 2000, ki jo proizvaja podjetje FARMTECH d.o.o. Ker prikolica obratuje, kjer so slabi cestni pogoji, je potrebno ob razvoju novega priklopa zagotoviti, da konstrukcija prenese dovolj velike obremenitve, katere se pojavijo med samim obratovanjem. Statična analiza se je izvedla s pomočjo programa SolidWorks, kjer smo z uporabo MKE dobili vpogled v napetostno stanje konstrukcije priklopa ter vpetja na podvozje prikolice. Model priklopa smo obremenili na dva različna načina. Po analizi dobljenih rezultatov, smo ugotovil, da priklop ne ustreza našim zahtevam, zato smo ga ustrezno spremenili, da zagotavlja statično trdnost konstrukcije.
Ključne besede: trdnostni preračun, računalniške simulacije, metode končnih elementov (MKE), SolidWorks
Objavljeno v DKUM: 07.10.2021; Ogledov: 778; Prenosov: 123
Celotno besedilo (4,02 MB)