Ab-initio elastic tensor of cubic Ti0.5_{0.5}Al0.5_{0.5}N alloy: the dependence of the elastic constants on the size and shape of the supercell model

In this study we discuss the performance of approximate SQS supercell models in describing the cubic elastic properties of B1 (rocksalt) Ti$_{0.5}$Al$_{0.5}$N alloy by using a symmetry based projection technique. We show on the example of Ti$_{0.5}$Al$_{0.5}$N alloy, that this projection technique can be used to align the differently shaped and sized SQS structures for a comparison in modeling elasticity. Moreover, we focus to accurately determine the cubic elastic constants and Zener's type elastic anisotropy of Ti$_{0.5}$Al$_{0.5}$N. Our best supercell model, that captures accurately both the randomness and cubic elastic symmetry, results in $C_{11}=447$ GPa, $C_{12}=158$ GPa and $C_{44}=203$ GPa with 3% of error and $A=1.40$ for Zener's elastic anisotropy with 6% of error. In addition, we establish the general importance of selecting proper approximate SQS supercells with symmetry arguments to reliably model elasticity of alloys. In general, we suggest the calculation of nine elastic tensor elements - $C_{11}$, $C_{22}$, $C_{33}$, $C_{12}$, $C_{13}$, $C_{23}$, $C_{44}$, $C_{55}$ and $C_{66}$, to evaluate and analyze the performance of SQS supercells in predicting elasticity of cubic alloys via projecting out the closest cubic approximate of the elastic tensor. The here described methodology is general enough to be applied in discussing elasticity of substitutional alloys with any symmetry and at arbitrary composition.Comment: Submitted to Physical Review

An end to Nordic exceptionalism? Europeanisation and Nordic development policies

The Nordic countries have traditionally been praised for their generous and advanced development policies. Recently, however, it has been claimed that the Nordic model has faded: that the Nordic donors have become more similar to other European donors. One possible reason for such trends is influences from EU policies, that is, Europeanisation. This article critically evaluates such claims by presenting arguments for and against Europeanisation effects. We argue that changes have indeed taken place. The Nordic exceptionalism has been eroded. At the same time, a convergence of European aid policies has occurred. The question is if this is the consequence of Europeanisation – or is it rather a result of Nordicisation (the Nordic countries influencing the EU), or perhaps like-mindisation (a broader set of progressive member states having impact upon EU policies)? We suggest that Europeanisation has been extremely weak while there is strong evidence of Nordicisation but also, and increasingly, of like-mindisation. Today, a core group of mainly northern member states, including the Nordics, are the main driving forces behind European aid convergence

Significant elastic anisotropy in Ti1−x_{1-x}Alx_xN alloys

Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti$_{1-x}$Al$_x$ N alloys. The elastic constant, C$_{11}$, changes by more than 50% depending on the Al-content. Increasing the Al-content weakens the average bond strength in the local octahedral arrangements resulting in a more compliant material. On the other hand, it enhances the directional (covalent) nature of the nearest neighbor bonds that results in greater elastic anisotropy and higher sound velocities. The strong dependence of the elastic properties on the Al-content offers new insight into the detailed understanding of the spinodal decomposition and age hardening in Ti$_{1-x}$Al$_x$N alloys.Comment: 3 figures, 3 page

The Fantasy and Symbolism of Religious Poetry?A Case Study of The Waste Land, Paradise Lost and Prometheus Unbound

Mesoporous silica SBA-15 in the form of 10-30 μm sized sheets with unusually large ordered pores has been synthesized using heptane as a cosolvent in the presence of NH4F. The resulting morphology of 400 nm thick sheets that contain easily accessed, hexagonally arranged, 18 nm sized pores running parallel to sheet normal has not been previously reported. The material has a BET surface area of 541 m2/g, large pore volume of 1.69 cm3/g and ordered mesopore structure with a narrow pore size distribution around 18 nm. A mechanism for sheet formation based on heptane droplets acting as sites for self assembling of silica crystallites is suggested.Original Publication:Emma Johansson, Jose Manuel Cordoba and Magnus Odén, Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores, 2009, Materials Letters, (63), 24-25, 2129-2131.http://dx.doi.org/10.1016/j.matlet.2009.07.013Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com

Anharmonicity changes the solid solubility of an alloy at high temperatures

We have developed a method to accurately and efficiently determine the vibrational free energy as a function of temperature and volume for substitutional alloys from first principles. Taking Ti$_{1-x}$Al$_x$N alloy as a model system, we calculate the isostructural phase diagram by finding the global minimum of the free energy, corresponding to the true equilibrium state of the system. We demonstrate that the anharmonic contribution and temperature dependence of the mixing enthalpy have a decisive impact on the calculated phase diagram of a Ti$_{1-x}$Al$_x$N alloy, lowering the maximum temperature for the miscibility gap from 6560 K to 2860 K. Our local chemical composition measurements on thermally aged Ti$_{0.5}$Al$_{0.5}$N alloys agree with the calculated phase diagram.Comment: 4 pages, 5 figures, supplementary materia

Шляхи удосконалення підготовки учнів до олімпіад з фізики

(uk) Стаття присвячена проблемі формування основ методики складання задач та завдань для олімпіад з фізики учнів середніх навчальних закладів освіти.(ru) Статья посвящена проблеме формирования основ методики составления задач и заданий для олимпиад по физике учащихся средних учебных заведений образования

Mellanrum i staden

Uppsatsen undersöker hur mellanrum i staden definieras, och om Lunds Ungdoms- och Hemgårds trädgård kan räknas som ett mellanrum i staden. Detta görs bland annat genom en litteraturstudie där mellanrummens karaktärsdrag, vilken typ av aktiviteter som sker i dem, vilken roll de kan sägas ha, och ett antal begrepp kopplade till mellanrum i staden undersöks. Genom litteraturstudien skissas ett verktyg fram: ett teoretiskt ramverk över mellanrum i staden. Ramverket skulle kunna användas för identifiering av mellanrum i staden och dess kvalitéer. Uppsatsen består även av en fallstudie där en analys av Lunds Ungdoms- och Hemgårds trädgård gjorts utifrån litteraturstudien och det teoretiska ramverket. Fallstudien består av observationer av trädgården, intervju med trädgårdens besökare och Lunds Ungdoms- och Hemgårds personal. Syftet med arbetet är framförallt att bidra till kunskapsutvecklingen om mellanrum i staden och att genom en djupare förståelse kring dem kunna berika oss i vår yrkesroll som planerare och designers. Resultatet av studien visar att mellanrummen i staden är svåra att slutgiltigt definiera, och att de lämnar utrymme för olika aktiviteter som inte får plats i stadens mer väldefinierade rum. Studien visar också att mellanrummen i staden kan utveckla diskussionen kring rum. Detta eftersom de problematiserar arkitektens roll i förhållande till utveckling av programmerade miljöer och belyser att vi som programmerar rummen också kan komma att understödja rådande maktordning och normbildning, de problematiserar demokratiaspekten i stadens offentliga rum, och belyser att städer behöver platser som inte fungerar utestängande för det som inte faller inom normen. Uppsatsen kan på så sätt ge oss ett verktyg att kunna argumentera för vikten av mellanrummens existens. Resultatet av studien visar också genom fallstudien att det går att finna mellanrumskvalitéer i rum med mindre programmering, och kan därför öppna för en diskussion om att skapa den typen av rum i våra städer.This essay examines how to define urban interstices, and it also explores if “Lunds Ungdoms- och Hemgårds” garden is an urban interstice. This is made partly by a literature study where their characteristics, the activities they hold, what part they play in the city, and a couple of concepts connected with urban interstices are being studied. With this essay, a tool for identifying urban interstices and their qualities has been developed. The essay also contains a case study in which ”Lunds Ungdoms- och Hemgårds” garden is analyzed on the basis of the literature study and the tool. The case study is made from interviews and observations made at the location. The intentions of this study is to contribute to the development of knowledge of urban interstices and through a deeper understanding see how it can enrich our professional capacity as planners and designers. The results of this study show us that the urban interstices are hard to definitively define, and that they give space for activities that are having difficulties existing elsewhere in the city. The results also show that the urban interstices can contribute to the discussion of rooms, because of their capacity to problematize the architect’s role on developing programmed spaces. They also highlight the fact that the ones that program the spaces also may help the existent power structure and standard-settings. The urban interstices also problematizes the democracy of the public spaces in the city as well as highlight the fact that the city needs a type of places that do not exclude what doesn’t follow the norm. The results of the study can give us the tool to argue for the importance of the existence of urban interstices. The study also show us that there are qualities found in the urban interstices which can also be found in the less programmed spaces of the city. This can open up a debate about creating less programmed spaces in our cities

Growth and thermal stability of TiN/ZrAlN: Effect of internal interfaces

Wear resistant hard films comprised of cubic transition metal nitride (c-TMN) and metastable c-AlN with coherent interfaces have a confined operating envelope governed by the limited thermal stability of metastable phases. However, equilibrium phases (c-TMN and wurtzite(w)-AlN) forming semicoherent interfaces during film growth offer higher thermal stability. We demonstrate this concept for a model multilayer system with TiN and ZrAlN layers where the latter is a nanocomposite of ZrN- and AlN- rich domains. The interfaces between the domains are tuned by changing the AlN crystal structure by varying the multilayer architecture and growth temperature. The interface energy minimization at higher growth temperature leads to formation of semicoherent interfaces between w-AlN and c-TMN during growth of 15 nm thin layers. Ab initio calculations predict higher thermodynamic stability of semicoherent interfaces between c-TMN and w-AlN than isostructural coherent interfaces between c-TMN and c-AlN. The combination of a stable interface structure and confinement of w-AlN to nm-sized domains by its low solubility in c-TMN in a multilayer, results in films with a stable hardness of 34 GPa even after annealing at 1150 °C.Peer ReviewedPostprint (author's final draft

Hadtörténelmi Közlemények

Under 1990-talet skedde stora samhällsförändringar inom både ekonomiska och politiska områden. Skolan förändrades från en centraliserad till en decentraliserad organisation. Kommunerna fick ta ett större ansvar för den lokala skolan och mål- och resultatstyrning infördes i förskolan, grundskolan och på gymnasiet. Det uppkom en politisk föreställning om att det föränderliga samhället och den ökade internationella konkurrensen skapar nya förutsättningar på arbetsmarknaden, vilket i sin tur ställer nya krav på kunskaper och utbildning. Begreppet livslångt lärande kom därigenom att framställas som lösningen på hur medborgarna ska klara dessa förändringar. Studien belyser arbetet kring livslångt lärande och individuell utveckling samt hur eleverna i grundskolan ska uppnå målen i läroplanen och kursplanerna. Studien syftar till att undersöka vilka styrningspraktiker som kan ligga bakom hur individen ska utvecklas i skolan för att leva upp till och bli en del av det livslånga lärandet. Detta görs genom att studera olika offentliga dokument och utredningar om den svenska grundskolan. Utgångspunkten är en Foucaultinspirerad diskursanalys med inriktning på perspektivet governmentality. Studien har påvisat att det används olika verktyg och teknologier som ska leda till former av självstyrning, självreglering och kontroll av eleven. I analysen lyfts fram olika styrningspraktiker som används för att skapa det livslångt lärande subjektet, där framförallt lärarens och elevens roll belyses. Bland annat diskuteras individuella utvecklingsplaner och utvecklingssamtal för hur elevens kunskapsbildning och lärande ska förbättras

Enhanced thermal stability and fracture toughness of TiAlN coatings by Cr, Nb and V-alloying

The effect of metal alloying on mechanical properties including hardness and fracture toughness were investigated in three alloys, Ti~0.33Al0.50(Me)~0.17N (Me¿=¿Cr, Nb and V), and compared to Ti0.50Al0.50N, in the as-deposited state and after annealing. All studied alloys display similar as-deposited hardness while the hardness evolution during annealing is found to be connected to phase transformations, related to the alloy's thermal stability. The most pronounced hardening was observed in Ti0.50Al0.50N, while all the coatings with additional metal elements sustain their hardness better and they are harder than Ti0.50Al0.50N after annealing at 1100¿°C. Fracture toughness properties were extracted from scratch tests. In all tested conditions, as-deposited and annealed at 900 and 1100¿°C, Ti0.33Al0.50Nb0.17N show the least surface and sub-surface damage when scratched despite the differences in decomposition behavior and h-AlN formation. Theoretically estimated ductility of phases existing in the coatings correlates well with their crack resistance. In summary, Ti0.33Al0.50Nb0.17N is the toughest alloy in both as-deposited and post-annealed states.Peer ReviewedPostprint (author's final draft