38 resultados para Fine-grained microstructure
Resumo:
We study the computational complexity of finding maximum a posteriori configurations in Bayesian networks whose probabilities are specified by logical formulas. This approach leads to a fine grained study in which local information such as context-sensitive independence and determinism can be considered. It also allows us to characterize more precisely the jump from tractability to NP-hardness and beyond, and to consider the complexity introduced by evidence alone.
Resumo:
The bacterial community composition and biomass abundance from a depositional mud belt in the western Irish Sea and regional sands were investigated by phospholipid ester-linked fatty acid profiling, denaturing gradient gel electrophoresis and barcoded pyrosequencing of 16S rRNA genes. The study area varied by water depth (12-111 m), organic carbon content (0.09-1.57% TOC), grain size, hydrographic regime (well-mixed vs. stratified), and water column phytodetrital input (represented by algal polyunsaturated PLFA). The relative abundance of bacterial-derived PLFA (sum of methyl-branched, cyclopropyl and odd-carbon number PLFA) was positively correlated with fine-grained sediment, and was highest in the depositional mud belt. A strong association between bacterial biomass and eukaryote primary production was suggested based on observed positive correlations with total nitrogen and algal polyunsaturated fatty acids. In addition, 16S rRNA genes affiliated to the classes Clostridia and Flavobacteria represented a major proportion of total 16S rRNA gene sequences. This suggests that benthic bacterial communities are also important degraders of phytodetrital organic matter and closely coupled to water column productivity in the western Irish Sea.
Resumo:
This book explores what it is like to be involved in contemporary open adoption, characterised by varying forms of contact with birth relatives, from an adoptive parent point of view.
The author’s fine-grained interpretative phenomenological analysis of adopters’ accounts reveals the complexity of kinship for those whose most significant relationships are made, unmade and permanently altered through adoption. MacDonald distinctively connects adoption to wider sociological theories of relatedness and personal life, and focuses on domestic non-kin adoption of children from state care, including compulsory adoption. The book also addresses current child welfare concerns, and suggestions are made for adoption practice. The book will be of interest to scholars and students with an interest in adoption, social work, child welfare, foster care, family and sociology.
Resumo:
At QUB we have constructed a system that allows students to self-assess their capability on the fine grained learning outcomes for a module and to update their record as the term progresses. In the system each of the learning outcomes are linked to the relevant teaching session (lectures and labs) and to [online] resources that students can access at any time. Students can structure their own learning experience to their needs to attain the learning outcomes. The system keeps a history of the student’s record, allowing the lecturer to observe how the students’ abilities progress over the term and to compare it to assessment results. The system also keeps of any of the resource links that student has clicked on.
Resumo:
With the new academic year structure encouraging more in-term assessment to replace end-of-year examinations one of the problems we face is assessing students and keeping track of individual student learning without overloading the students and staff with excessive assessment burdens.
In the School of Electronics, Electrical Engineering and Computer Science, we have constructed a system that allows students to self-assess their capability on a simple Yes/No/Don’t Know scale against fine grained learning outcomes for a module. As the term progresses students update their record as appropriately, including selecting a Learnt option to reflect improvements they have gained as part of their studies.
In the system each of the learning outcomes are linked to the relevant teaching session (lectures and labs) and to online resources that students can access at any time. Students can structure their own learning experience to their needs and preferences in order to attain the learning outcomes.
The system keeps a history of the student’s record, allowing the lecturer to observe how the students’ abilities progress over the term and to compare it to assessment results. The system also keeps of any of the resource links that student has clicked on and the related learning outcome.
The initial work is comparing the accuracy of the student self-assessments with their performance in the related questions in the traditional end-of-year examination.
Resumo:
A Fe-8.46%Mn-0.24%Nb-0.038%C (wt.%) manganese steel was investigated. The steel has a 100% bcc structure after heat treatment at 850°C for 1.5 h, water quenching or air cooling. Martensite interlocked microstructure consisting of fine martensite plates/needles with different spatial orientations was found. Austenite forms, in small amounts, after a 600°C reheating treatment. Scanning electron microscopy images and energy dispersive spectrometry of the fracture surfaces revealed both ductile and brittle types of failure and precipitates. Deep quenching after the heat treatments does not change the phase composition or the hardness. NbC is formed in the steel, in high number densities. It plays a role in the impact fracture process, by acting as void nucleation sites, facilitating ductile fracture with dimples appearing on the fracture surface.
Resumo:
Because of the requirements for the damage tolerance and fatigue life of commercial aircraft components, the high cycle fatigue (HCF) properties of Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy forgings are important. The effects of microstructure types of the α+β titanium alloy on fatigue properties need to be understood. In this paper, by analysing the fracture surfaces of the titanium alloy having four types of microstructure, the effects of microstructure are investigated. The differences of initiation areas and crack propagation among different microstructures were studied. It was found that the area of the initiation region decreases in the order of coarse basketweave, fine basketweave, Widmanstätten, and bimodal microstructure.
Resumo:
Nitride-strengthened reduced activation ferritic/martensitic (RAFM) steels are developed taking advantage of the high thermal stability of nitrides. In the current study, the microstructure and mechanical properties of a nitride-strengthened RAFM steel with improved composition were investigated. Fully martensitic microstructure with fine nitrides dispersion was achieved in the steel. In all, 1.4 pct Mn is sufficient to suppress delta ferrite and assure the steel of the full martensitic microstructure. Compared to Eurofer97, the steel showed similar strength at room temperature but higher strength at 873 K (600 °C). The steel exhibited very high impact toughness and a low ductile-to-brittle transition temperature (DBTT) of 243 K (–30 °C), which could be further reduced by purification.