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Abstract: Potreba in zahteva po protimikrobni obdelavi tekstilij je zelo velika. Raziskanih je že precej različnih spojin, ki imajo te lastnosti, vendar jih je veliko škodljivih za ljudi in okolje. Zato je trend v iskanju naravnih in neškodljivih protimikrobnih sredstev. Žal pa je njihova vezava na tekstilno matrico in tudi stopnja učinkovitosti po navadi slabša. Problem s katerim smo se soočili že v diplomskem delu je, da smo dobili redukcijo mikroorganizmov na vzorcih, ki sploh niso bili obdelani s protimikrobnim sredstvom. Učinkovitost obdelanih tekstilij s protimikrobnimi sredstvi se določa z različnimi metodami, standardiziranimi in nestandardiziranimi. Vsaka od teh metod ima različen pristop k vrednotenju. Najbolj pogosto uporabljene so AATCC 100, AATCC 147, ASTM E 2149 in JIS L 1902. Problem pri nekaterih metodah je, da so rezultati pokazali nerazumljivo inhibicijo patogenih organizmov, kjer naj ne bi bila prisotna kot na primer pri neobdelanem vzorcu. Velikokrat prihaja tudi do napačne interpretacije rezultatov. Zato smo se v tem magistrskem delu osredotočili na testiranje neobdelanih tekstilnih vzorcev po različnih metodah. Izbrali smo najbolj pogoste in nam dostopne metode ASTM E 2149, ASTM E 2315 in JIS L 1902. Vzorce smo dali testirati v različne laboratorije. Kot vidimo v poglavju, Rezultati in meritve v preglednici 4.10 smo kljub temu dobili redukcijo mikroorganizmov. Zato smo preučili vpliv fizikalno-kemijskih parametrov vlaken, na mikrobiološke lastnosti vlaken.
Keywords: celuloza, bombaž, viskoza, PES vlakna, mikrobiološko testiranje, time-kill metoda ASTM E 2315, stresalna metoda ASTM E 2149, JIS L 1902, tenziometer, stični kot, površinska napetost, površinska energija
Published in DKUM: 04.04.2014; Views: 2298; Downloads: 194
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Abstract: Unemployment negatively affects the government budget and inflicts costs on the unemployed individuals as well as on the society as a whole in many ways. The direct costs of unemployment for the state budget arise due to the benefits paid out to the unemployed, and due to foregone direct and indirect taxes. On the level of an individual, nonmonetary costs are a multiple of the monetary ones, which indicates that employment plays a central role in a person’s well-being. Unemployment has a spill-over effect on the society as a whole and affects not only the unemployed, but also the employed population, particularly in the areas experiencing high unemployment rates. We take the case study of Germany, the country often used as a quintessence of how to overcome the problem of massive unemployment. Before the four Hartz reforms, which were implemented in years 2003, 2004 and 2005, Germany was characterized as the »sick man of Europe« owing to its exploding levels of unemployment, dysfunctional labor market, unsustainable social budget, and rising public debt. As the reforms were put into force, the situation in the German labor market underwent a 360° turnaround and became portrayed as the »German economic miracle«. The true effects of the reforms fully transpired in the economic and financial crisis of 2008/2009, when most countries experienced escalating unemployment rates, while Germany kept them at bay. Studies show that flexible working-time arrangements and short-time work have played a major role in inhibiting lay-offs in German companies during the recent crisis, and hence in preventing a spike in unemployment rates, which we use as one of the points that validate our Model of employment. The government subsidies made it possible for companies to reduce the working hours of their employees instead of laying them off. An important feature of the German labor market is a comparatively high percentage of part-time workers (around 25% in years 2006–2011), which also explains the low unemployment rates Germany has been recording since the reforms were introduced. The reforms cut the amount and duration of unemployment benefits, which gave the unemployed more incentives to find a job. A negative aspect of the reform may be an increased divide between the core work force and the marginal workers, which intensifies social differences and is currently on the agenda of German politics. Also some researches stress the importance of social cohesion and that the risks and opportunities in the labor market should be more evenly distributed. In the accompanying explanations to the Model of employment, some of the successful measures of Germany’s Hartz reforms may be spotted, while at the same time we avoid the »mistakes« of these reforms, thus making sure that social differences among people would narrow down upon the real-life implementation of the Model. When the number of job vacancies sharply exceeds the number of unemployed, and when there are poor prospects of new job openings in the near future, the only viable solution to the problem of unemployment is to reduce the working hours of the existing employees. The Model of employment that we develop represents a possible solution to the problem of unemployment and thus addresses the need to reduce the costs of unemployment to the unemployed individual, to the state budget, and to the society as a whole. The crux of the Model is a re-distribution of the total number of workplaces and total annual working hours among the »new actively employed population«, which comprises all persons having the potential to become or stay employed or self-employed in a given year. The model allows for a flexible arrangement of working hours – from four and up to eight hours per employee per day. Our solution will release the working hours, make them available to the currently unemployed, and hence ensure a more equitable distribution of income and work load amongst the population. In addition, as the workers will be less tired and stressed-out, their productivity will in
Keywords: unemployment, labor force, labor market, part-time employment, full-time employment, labor market flexibility, costs of unemployment, Hartz reforms
Published in DKUM: 30.08.2013; Views: 2601; Downloads: 170
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Abstract: This article is written for undergraduate students and teachers who would like to get familiar with basic nonlinear time series analysis methods. We present a step-by-step study of a simple example and provide user-friendly programs that allow an easy reproduction of presented results. In particular, we study an artificial time series generated by the Lorenz system. The mutual information and false nearest neighbour method are explained in detail, and used to obtain the best possible attractor reconstruction. Subsequently, the times series is tested for stationarity and determinism, which are both important properties that assure correct interpretation of invariant quantities that can be extracted from the data set. Finally, as the most prominent invariant quantity that allows distinguishing between regular and chaotic behaviour, we calculate the maximal Lyapunov exponent. By following the above steps, we are able to convincingly determine that the Lorenz system is chaotic directly from the generated time series, without the need to use the differential equations. Throughout the paper, emphasis on clear-cut guidance and a hands-on approach is given in order to make the reproduction of presented results possible also for undergraduates, and thus encourage them to get familiar with the presented theory.
Keywords: nonlinear systems, nonlinear time series analyses, physics education
Published in DKUM: 07.06.2012; Views: 2089; Downloads: 36
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Abstract: We study the spatial dynamics of noise-induced waves in two-dimensional excitable media in dependence on the duration of the artificially imposed refractory time that is introduced to each constitutive system unit after an excitation. Due to the introduction of refractory times, a randomly induced spatial wave is temporarily unable to transmit information to the opposite site of its propagation direction. Thus, once the wave leaves the absorbing boundaries of the spatial grid the system has little or no recollection, depending on the duration of the refractory time, of its existence. We show that even in the presence of such memory loss, self-organization of excitatory events leads to noise-induced spatial periodicity in the media. We present a simple analytical treatment of a two-unit system to capture and explain the essence of the observed phenomenon. Since refractory times are widespread in biological systems, our results provide interesting insights into functioning of real-life organisms at the cellular as well as tissue level.
Keywords: noise, spatiotemporal noise, intensity, pattern formation, refractory time, calcium oscillations
Published in DKUM: 07.06.2012; Views: 2229; Downloads: 97
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Abstract: Schoolwork, especially lessons in manual skills is often associated with various ergonomics stresses. These stresses are the result not only of school obligations but also of the physical working environment and inadequate lesson planning. Much can be done in this field if certain approaches are taken into consideration at the work planning stage. Thus we can use certain analytical methods, such as the Method of Temporary Observations (Multi-Moment Method) and OWAS (a method for the evaluation of postural load during work), when positioning stressful lesson factors. This can be done in arelatively simple way in the field of time rationalisation as well as in the field of dimensional work adjustment to pupils. Research results in this papershow that by using a planned directed approach in this field, it is possible to achieve, a higher level of efficiency with normal levels of fatigue.
Keywords: dimensional rationalisation, manual skills lessons, pupils, technology and design education, time rationalisation
Published in DKUM: 07.06.2012; Views: 1707; Downloads: 120
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