The nucleation and growth of η phase in nickel-based superalloy during long-term thermal exposure

The microstructure degradation and subsequent phase transformations in Waspaloy nickel-based superalloy during thermal exposure at 780 °C for 10,000 h were investigated. Two paths of η phase formation in the centre of extra-large γ’ (EL-γ’) following the formation of EL-γ’ were observed: (i) η phase directly precipitated within EL-γ’ when the coalescence of γ’ reached a critical stage; (ii) η phase precipitated at the interface of small size MC carbide and EL-γ’, with both MC and η embedded inside EL-γ’. The phase transformation process including the formation of EL-γ’ were experimentally observed and the formation sequences were schematically suggested. Two criteria of η formation and growth within EL-γ’ were established: (i) stacking faults formation in the nucleation site and (ii) sufficient atom diffusion during nuclei growth. The study of kinetics of η formation through two different paths revealed the critical role of small size carbides in promoting η nucleation and growth. It is concluded that η formation may be suppressed by controlling the size and density of MC carbides during materials processing

An investigation into establishing a generalised approach for defining similarity metrics between 3D shapes for case-based reasoning (CBR)

This thesis investigates the feasibility of establishing a generalised approach for defining similarity metrics between 3D shapes for the casting design problem in Case-Based Reasoning (CBR). This research investigates a new approach for improving the quality of casting design advice achieved from a CBR system using casting design knowledge associated with past cases. The new approach uses enhanced similarity metrics to those used in previous research in this area to achieve improvements in the advice given. The new similarity metrics proposed here are based on the decomposition of casting shape cases into a set of components. The research into metrics defines and uses the Component Type Similarity Metric (CTM) and Maximum Common Subgraph (MCS) metric between graph representations of the case shapes and are focused on the definition of partial similarity between the components of the same type that take into account the geometrical features and proportions of each single shape component. Additionally, the investigation extends the scope of the research to 3D shapes by defining and evaluating a new metric for the overall similarity between 3D shapes. Additionally, this research investigates a methodology for the integration of the CBR cycle and automation of the feature extraction from target and source case shapes. The ShapeCBR system has been developed to demonstrate the feasibility of integrating the CBR approach for retrieving and reusing casting design advice. The ShapeCBR system automates the decomposition process, the classification process and the shape matching process and is used to evaluate the new similarity metrics proposed in this research and the extension of the approach to 3D shapes. Evaluation of the new similarity metrics show that the efficiency of the system is enhanced using the new similarity metrics and that the new approach provides useful casting design information for 3D casting shapes. Additionally, ShapeCBR shows that it is possible to automate the decomposition and classification of components that allow a case shape to be represented in graph form and thus provide the basis for automating the overall CBR cycle. The thesis concludes with new research questions that emerge from this research and an agenda for further work to be pursued in further research in the area

THE BEHAVIOR OF THE MARGIN OF STABILITY DURING ABLE-BODIED TRUNK-FLEXED GAIT

The dynamic margin of stability (MoS), defined as the difference between the anterior boundary of the base of support and the extrapolated whole-body center of mass (WBCM) at foot touchdown, reflects the control of gait dynamic stability. This study explores the behavior of MoS during level walking in able-bodied walkers (n = 10) under altered sagittal trunk orientations, including ~30°, ~50° and maximal trunk flexion from the vertical compared with upright posture. Exploiting compensatory kinematic adjustments (e.g., crouched lower-limbs) possibly allowed participates to control their postural stability, as increasing trunk flexion did not lead to a significant diminish in the MoS relative to regular upright walking. Our findings might be of clinical interest to clinician interested in the nature and impact of alteration in trunk geometry on the control of gait dynamic stability

Effect Of Aggregate Propertıes On The Mechanıcal And Absorptıon Characterıstıcs Of Geopolymer Mortar

Üretiminde önemli çevresel sorunlara neden olan Portland çimentosunun imalatı için çeşitli doğal kaynaklar tüketilmektedir. Jeopolimerizasyon adı verilen yeni bir teknolojik süreç bu konuda yenilikçi bir çözüm getirmektedir. Jeopolimerler karbon emisyonu potansiyelini düşürmenin yanı sıra, uçucu kül, öğütülmüş yüksek fırın cürufu, metakaolin, vb. gibi birçok endüstriyel atık ürünü veya doğal puzolan ile sentezlenebilir. Bu çalışmada, uçucu kül esaslı jeopolimer harcın agrega özellikleri ile bazı mühendislik özellikleri arasındaki ilişkiyi ortaya koymak amacıyla deneysel bir çalışma yürütülmüştür. Bu amaç doğrultusunda, agrega olarak iki tür kum ve dört farklı gradasyon kullanılmıştır. Jeopolimer bağlayıcı, alkalin sıvılar ve uçucu kül karışımından oluşmaktadır. Kırma kireç taşı, karışık kum ve doğal kum için sırasıyla basınç dayanımı değerleri 47.83-40.25 MPa, 44.93-38.09 MPa, ve, 39.37-28.25 MPa aralığındadır. Ayrıca, su emme ve kılcal su emme deneyleri ile jeopolimer harçların geçirimlilikleri değerlendirilmiştir. Elde edilen test sonuçlarına göre uçucu kül esaslı jeopolimer harcın su emme kapasitesinin karışık agregalı olanlarda (%50 kırma kireç taşı ve %50 doğal kum), tek tip agregalı olanlara kıyasla iyileştiği gözlenmiştir

Multi-Core Parallel Routing

The recent increase in the amount of data (i.e., big data) led to higher data volumes to be transferred and processed over the network. Also, over the last years, the deployment of multi-core routers has grown rapidly. However, such big data transfers are not leveraging the powerful multi-core routers to the extent possible, particularly in the key function of routing. Our main goal is to find a way so we can use these cores more effectively and efficiently in routing the big data transfers. In this dissertation, we propose a novel approach to parallelize data transfers by leveraging the multi-core CPUs in the routers. Legacy routing protocols, e.g. OSPF for intra-domain routing, send data from source to destination on a shortest single path. We describe an end-to-end method to distribute data optimally on flows by using multiple paths. We generate new virtual topology substrates from the underlying router topology and perform shortest path routing on each substrate. With this framework, even though calculating shortest paths could be done with well-known techniques such as OSPF's Dijkstra implementation, finding optimal substrates so as to maximize the aggregate throughput over multiple end-to-end paths is still an NP-hard problem. We focus our efforts on solving the problem and design heuristics for substrate generation from a given router topology. Our heuristics' interim goal is to generate substrates in such a way that the shortest path between a source-destination pair on each substrate minimally overlaps with each other. Once these substrates are determined, we assign each substrate to a core in routers and employ a multi-path transport protocol, like MPTCP, to perform end-to-end parallel transfers

The effects of time management workshops on students` academic success: A study on foundation english students at Tishk International University

Time management skills have been considered fundamental to improve 21st century skills related to learning, literacy and life. Commanding the time precisely can facilitate people`s lives in many aspects. Conversely, people who are terrible at managing their time can encounter many problems throughout their lives. In this regard, the main aim of this study which was conducted by a mixed method design was to measure the effects of time management workshops on students` overall success in Foundation English course at Tishk International University located in Erbil, Iraq in 2021-2022 Academic Year. Correspondingly, 30 students in 5 different departments were chosen by convenience sampling method for this study which had a span of 8 weeks. The participants in the control group received a traditional instruction with printed copies on time management, while participants in the experimental group underwent a training period with three time management workshops. The data were collected via a questionnaire, an interview and two exams. SPSS 27 and MAXQDA were primary instruments to analyze the data. The former one was used to analyze the exams through independent samples t test, whereas the latter one was used to transcribe the expressions in the interview. The findings revealed that the students in experimental group outperformed in terms of success in the exams, the level of motivation and transforming their lives positively. The implications of this study can pave the way to integrate time management workshops into the curriculum at educational institutions globally

Lorettine Educational History in New Mexico

The purpose of this study is to relate the history of the first American Community--the Sisters of Loretto--who crossed the American Desert in 1852 to establish schools in New Mexico, and to narrate the account of the foundation, organization, and development of each school in chronological order. Today the Sisters conduct eight elementary schools and four high schools in the State. Some of these schools, begun nearly a century ago within small adobe walls, are now recognized as establishments of culture and learning

Efficacy of life skills training on increase of mental health and self esteem of the students

AbstractThe aim of this study is to achieve to effects of life skills training on providing mental health and self esteem of university students. The study method was experimental research method. The type of design was before- after test design with control group. Statistical society of the present study comprised all boys’ students accepting at 2009 and studying at University of Mohaghegh Ardabili in 2009. Also, this study was conducted only on the individuals who gained 28 or more in DASS questionnaire (which evaluates three subscales of anxiety, depression, and stress), (n=210). At the next stage the needed sample (i.e. 40 boy students {20 individuals in control group and 20 individuals in experimental group}) was selected randomly and distributed in two mentioned groups, randomly. Then, life skills were taught to experimental group for 8 sessions in four week) and no variable was exposed to control group during this period. At the end, 3 individuals from experimental group were omitted; finally the achieved data from 37 individuals was analyzed by descriptive statistics methods (frequently and percentage) as well as inferential statistics methods (independent t test, MANOVA). The results showed that life skills training affects on decreasing mental disorders symptoms especially anxiety, depression and stress of students suspected to the mental disorder. This study showed that life skills training is a good method in decreasing mental disorders symptoms among the students suspected to the mental disorder

The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air

Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500ºC for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500oC on the tensile ductility of two differently processed Ti-834 alloys was investigated. In order to simulate actual Ti-834 processing routes, forged and centrifugally cast materials were used. The tensile tests were conducted on various specimens exposed at 500ºC for 100, 200 and 500 hours to observe microstructure feature changes. Moreover, the effect of microstructure, microtexture, α-case, α2 and silicide precipitate coarsening during high temperature exposure was studied thoroughly. The cast alloy was found to have a minimum ductility and failed at 1.8% strain after exposure at 500oC/500 hour when the α-case layer was retained during testing, whilst, the ductility of the forged alloy was unaffected. The effects of individual microstructural parameters on the ductility regression in Ti-834 alloy were quantified. The results showed that 7.1% strain differences between the cast and forged alloy are related to microstructural variations including; morphology, lath widths, grain size and shape, grain orientations and microtexture. A total of 9.6 % strain loss was observed in centrifugally cast Ti-834 after aging at 500ºC/500h and quantified as follow; 3.6% due to α-case formation during high temperature exposure, 0.2% due to α2-precipitates coarsening, 4.4% due to further silicide formation and coarsening, 1.4% due to additional microstructure changes during high temperature exposure. Furthermore, silicide coarsening on α/β phase boundaries caused large void formation around the precipitates. A theoretical model supported by experimental observations for silicide precipitation in fully colony and duplex microstructures was established. The element partitioning during exposure caused Al and Ti depletion in the vicinity of the β phase in the lamellae, i.e., αs area. This resulted in lowering the strength of the alloy and facilitated the formation of Ti3(SiZr)2 precipitates. The Al depletion and nano-scale partitioning observed at the αs/β boundaries resulted in easy crack initiation and promoted propagation in the centrifugally cast colony microstructure and reduced the basal slip τcrss. Furthermore, silicides were not formed in αp (high Al, Ti and low Zr areas) in the forged duplex microstructure that promoted superior mechanical performance and ductility over the cast alloy