Dependence of mechanical properties on Cu content in AlSi9Cu3(Fe) alloy

Legura aluminija AlSi9Cu3(Fe) je jedna od najčešće korištenih aluminijevih legura jer je njezina primjena temeljena na dobrim mehaničkim svojstvima. U proizvodnji često nastaju odstupanja od maksimalno dopuštenih granica pojedinih legirajućih elemenata, posebice bakra. Budući da mehanička svojstva gotovih proizvoda iz ovih legura ovise o sadržaju bakra, različiti udjeli bakra su dodavani osnovnoj leguri, a sadržaj kemijskih elemenata je praćen pomoću optičkog spektrometra, ispitivanja tvrdoće HB i mjerenja vlačne čvrstoće. Uz ova ispitivanja, analiziran je i utjecaj bakra na oksidacijska svojstva i korozijsku postojanost. Najbolji rezultati dobiveni su za 3 wt. % udjela Cu.AlSi9Cu3(Fe) aluminium alloy is one of the most commonly used casting aluminium alloys because their utility is based on good mechanical properties. Production often leads to deviations of maximum levels for certain alloying elements, particularly copper. Since mechanical properties of the final products of these alloys strongly depend on the concentration of copper in the alloy, various concentrations of copper were added to the basic alloy whereas the chemical composition was monitored using an optical emission spectrometer, measuring Brinell hardness and doing tensile tests. Moreover, the impacts of copper on oxidizing and corrosion resistance of the experimental alloys were analysed. The alloy with 3 wt. % Cu showed the best results

The Influence of Foundry Scrap Returns on Chemical Composition and Microstructure Development of AlSi9Cu3 Alloy

Recycling is now, more than ever, an important part of any foundry process due to the high cost of energy. The basis of the work presented here is a study of the addition of foundry scrap returns to the melt in order to reduce material and energy costs. The most important issue in such a process is the quality of both the prepared melt and final product. In this work, scrap returns were added to the AlSi9Cu3 base alloy in different proportions. Chemical composition was monitored, the solidification path was predicted by CALPHAD calculations and monitored by thermal analysis, and the formed microstructure was studied. The mechanical properties were also determined. The results showed that as the amount of scrap returns increased, elements such as Fe, Ni, Pb, Sr, etc. were more built up and elements such as Mg, Mn, Cr, etc. were decreased due to oxidation. The different chemical composition led to a reduced Mn:Fe ratio, resulting in the formation of needle-like Fe-rich phases and a decrease in mechanical properties

The use of social stories for gaining social and communication skills with a child with intellectual disability and autism

Avtistične motnje so dandanes v porastu, pojavljajo se lahko kot samostojna motnja ali pa skupaj z drugimi razvojnimi motnjami. Ena izmed pogostih značilnosti oseb z avtističnimi motnjami je neustrezno vedenje, ki je tudi posledica nerazumevanja, kakšno vedenje je v določeni situaciji primerno. Učenje socialno primernega načina vedenja in novih spretnosti poteka na različne načine, tudi preko socialnih zgodb. Le-te skušajo pojasniti specifično situacijo skozi oči otroka z avtistično motnjo in mu s konkretnimi idejami pomagati, kako se odzvati na primeren način. V magistrskem delu je bila izvedena študija primera z devet let starim učencem, ki ima lažjo motnjo v duševnem razvoju, avtistično motnjo in lažjo gibalno oviranost in se izobražuje v prilagojenem programu vzgoje in izobraževanja z nižjim izobrazbenim standardom. Cilj dela je bilo oblikovati individualiziran program obravnave socialnih zgodb in ugotoviti, ali socialne zgodbe pomembno učinkujejo pri učenju novih socialnih in komunikacijskih spretnosti. Raziskovala sem tudi, ali bo učenec nove spretnosti po končani obravnavi še vedno uporabljal. Ustvarila sem štiri socialne zgodbe, ki so se navezovale na problemske situacije, v katerih je deček večkrat izkazal nerazumevanje dogodkov. V devetih tednih sem izvedla 14 individualnih obravnav na katerih sem učencu preko različnih metod dela predstavila socialne zgodbe in raziskovala, katere metode dela so bile za otroka najučinkovitejše Rezultati, beleženi s štirimi individualno prilagojenimi ocenjevalnimi lestvicami, so pokazali napredek na področju uporabe novih socialnih in komunikacijskih spretnosti. Učenec je nove spretnosti uporabljal delno uspešno, tako med kot po zaključeni obravnavi socialnih zgodb. Kot najučinkovitejša metoda dela se je izkazala metoda razlage v kombinaciji s še eno izmed praktičnih metod dela – igro z lutkami ali igro vlog. Rezultate, pridobljene z analizo rezultatov ocenjevalnih lestvic, sem podkrepila še z ugotovitvami neposrednega opazovanja ter pogovora z učenčevima učiteljicama in starši. V zaključku magistrskega dela sem predstavila prednosti uporabe socialnih zgodb, ki sem jih opazila tekom celotne študije primera.Nowadays, the number of cases of autism has increased. They may emerge as an autonomous disorder or combined with other developmental disorders. One of the most frequent characteristics of people with autism is inappropriate behaviour, which originates in the lack of understanding of the social context, i.e. what kind of behaviour is acceptable in a particular situation. The teaching of socially acceptable ways of behaving and social skills is conducted in various ways, including social stories. The purpose of these stories is to explain a specific situation from the point of view of a child with autism, offering concrete ideas as to how to react in a proper way. For the purposes of the master’s thesis, I conducted a study of a nine-year-old student with a mild intellectual disability, autism and a mild physical disability. The student attends an adapted education programme with a lower educational standard. The main aims were to form an individualised programme of discussing social stories and to assess the effect of social stories on the acquisition of new social and communication skills. I also monitored whether the student continued to use the newly acquired social and communication skills or not. I designed four social stories addressing situations, where the boy previously experienced difficulties with understanding the events. Fourteen individual lessons stretched over nine weeks. During the sessions, parts of the social stories were presented to the student, using different methodology in order to establish the most efficient approach. Using four individualised assessment scales, the results showed an improvement in the use of the new social and communication skills. The student was partly successful in using the newly acquired skills both during the lessons and after them. Explanation combined with a practical method (using muppets or a role-play) proved to be the most effective approach. The results acquired through the analysis of assessment scales were additionally strengthened by the findings of direct monitoring and the interviews of the student’s teachers and parents. At the end of the thesis, I presented the advantages of using social stories that I observed throughout the case study

The use of social stories for gaining social and communication skills with a child with intellectual disability and autism

Nowadays, the number of cases of autism has increased. They may emerge as an autonomous disorder or combined with other developmental disorders. One of the most frequent characteristics of people with autism is inappropriate behaviour, which originates in the lack of understanding of the social context, i.e. what kind of behaviour is acceptable in a particular situation. The teaching of socially acceptable ways of behaving and social skills is conducted in various ways, including social stories. The purpose of these stories is to explain a specific situation from the point of view of a child with autism, offering concrete ideas as to how to react in a proper way. For the purposes of the master’s thesis, I conducted a study of a nine-year-old student with a mild intellectual disability, autism and a mild physical disability. The student attends an adapted education programme with a lower educational standard. The main aims were to form an individualised programme of discussing social stories and to assess the effect of social stories on the acquisition of new social and communication skills. I also monitored whether the student continued to use the newly acquired social and communication skills or not. I designed four social stories addressing situations, where the boy previously experienced difficulties with understanding the events. Fourteen individual lessons stretched over nine weeks. During the sessions, parts of the social stories were presented to the student, using different methodology in order to establish the most efficient approach. Using four individualised assessment scales, the results showed an improvement in the use of the new social and communication skills. The student was partly successful in using the newly acquired skills both during the lessons and after them. Explanation combined with a practical method (using muppets or a role-play) proved to be the most effective approach. The results acquired through the analysis of assessment scales were additionally strengthened by the findings of direct monitoring and the interviews of the student’s teachers and parents. At the end of the thesis, I presented the advantages of using social stories that I observed throughout the case study

Oxidation resistance of cast magnesium alloys

International audienceAu cours du XIXe siècle, la notion de détail s’est imposée comme un outil théorique majeur pour l’appréhension des images et comme un élément essentiel de la réflexion sur la représentation et ses techniques. Stimulée par l’apparition de l’image photographique dont le rendu exceptionnellement détaillé a joué un rôle de catalyseur, la réflexion sur le détail a gagné différentes sphères culturelles

Assessment of Air Pollution in Different Areas (Urban, Suburban, and Rural) in Slovenia from 2017 to 2021

Air pollution can have a significant effect on human health. The present work is focused on the investigation of daily, monthly, and annual concentration levels of five typical air pollutants (SO2, NO2, NOX, PM10, and PM2.5) in the Republic of Slovenia (RS) from January 2017 to December 2021. The study was conducted at five different monitoring stations of the following kind: traffic (A), industrial (D), and background (B, C, E). The obtained results showed a decline in the average concentrations for all the studied air pollutants through the years, respectively. The daily average SO2 concentrations were the lowest in the year 2021 at location B, which is classified as background location, while the highest were detected in the year 2018 at location E, which is also classified as background location. The average daily concentrations of NO2 and NOX were the highest at location A in the year 2017, whereas the lowest were detected in the year 2010 and 2021. It is believed that those results are a consequence of measures set by the Slovenian government during the COVID-19 pandemic. The PM10 and PM2.5 daily average concentrations were the highest at location A in 2017, while the lowest were observed in the year 2019 at location C. Meteorological parameters (temperature, wind speed, and relative humidity) were studied in addition. In general, the high temperatures in ambient air are responsible for the intense concentrations of air pollutants. It was found in the study results for temperature, wind speed, and relative humidity that no significant difference was shown between studied years

Comparison of cycling high temperature corrosion at 650°C in the presence of NaCl of various austenitic stainless steels

The high temperature corrosion at 650°C in the presence of NaCl at atmospheric pressure of AISI 304L, AISI 309, AISI 310S, AISI 314 and AISI 321 austenitic stainless steel was studied. The specimens were cyclically heated in the furnace and immersed in a 3.5% aqueous NaCl solution after cooling for 15 min. After each cycle, the change in mass of the samples was measured. The corroded samples were analysed by SEM /EDX, and the corrosion products were analysed by XRD. The chloride ions react with the steel surface to form porous and poorly adherent oxides and metal chlorides. After the mass increase during the first exposure cycles, spalling of the oxides occurred. The high temperature austenitic stainless steels (AISI 309, AISI 310S, AISI 314) showed less mass loss than conventional austenitic steels (AISI 304L). Surprisingly, the stainless steel AISI 321 showed a similar low weight loss after the cyclic test as AISI 309, but a detailed analysis of the exposed surfaces after the test showed a similar corrosion attack as for AISI 304. After the cyclic test at high temperature in the presence of NaCl, a higher concentration of Cr and Ni definitely improves the corrosion resistance under the present conditions, but a certain addition of Si is even more obvious