Computational homogenization of liquid-phase sintering with seamless transition from macroscopic compressibility to incompressibility

Liquid phase sintering of particle agglomerates is modeled on the mesoscale as the viscous deformation of particle-particle contact, whereby the single driving force is the surface tension on the particle/pore interface. On the macroscale, a quasistatic equilibrium problem allows for the prediction of the shrinkage of the sintering body. The present paper presents a novel FE2 formulation of the two-scale sintering problem allowing for the transition to zero porosity, implying macroscale incompressibility. The seamless transition from compressibility to incompressibility on the macroscale is accomplished by introducing a mixed variational format. This has consequences also for the formulation of the mesoscale problem, that is complemented with an extra constraint equation regarding the prolongation of the volumetric part of the macroscopic rate-of-deformation. The numerical examples shows the sintering of a single representative volume element (RVE) which is sheared beyond the point where the porosity vanishes while subjected to zero macroscopic pressure. © 2013 The Authors

On the variationally consistent computational homogenization of elasticity in the incompressible limit

Background Computational homogenization is a well-established approach in material modeling with the purpose to account for strong micro-heterogeneity in an approximate fashion without excessive computational cost. However, the case of macroscopically incompressible response is still unresolved. Methods The computational framework for Variationally Consistent Homogenization (VCH) of (near) incompressible solids is discussed. A canonical formulation of the subscale problem, pertinent to a Representative Volume Element (RVE), is established, whereby complete macroscale incompressibility is obtained as the limit situation when all constituents are incompressible. Results Numerical results for single RVEs demonstrate the seamless character of the computational algorithm at the fully incompressible limit. Conclusions The suggested framework can seamlessly handle the transition from (macroscopically) compressible to incompressible response. The framework allows for the classical boundary conditions on the RVE as well as the generalized situation of weakly periodic boundary conditions

Methodologies for tracking learning paths: designing the online research study Making a Filmmaker

The article concerns the design of a collaborative research project (2008-09) entitled Making a Filmmaker, which examines how young Scandinavian filmmakers create their own learning paths in formal and/or informal contexts. Our interest is in how learning experiences and contexts motivate the young filmmakers: what furthers their interest and/or hinders it, and what learning patterns emerge. The aim of this article is to present and discuss issues regarding the methodology and methods of the study, such as developing a relationship with interviewees when conducting interviews online (using MSN). We suggest two considerations about using online interviews: how the interviewees value the given subject of conversation and their familiarity with being online. The benefit of getting online communication with the young filmmakers is the ease it offers, because it is both practical and appropriates a meeting platform that is familiar to our participants.Artiklen handler om forskningsdesign af et kollaborativt projekt (2008-09), At skabe en filmskaber, som handler om hvordan unge, skandinaviske filmskabere skaber deres egne læringsveje i formelle, semi-formelle og/eller uformelle kontekster. Vores overordnede interesse i projektet er at se på hvordan de unges oplevelser og kontekster påvirker deres læringsprocesser. Målet med denne artikel er at præsentere og diskutere problemstillinger angående vores anvendte metodik og metoder, herunder at udvikle et forhold med informanter via skriftlige online-interviews (med MSN). Vi drøfter både den praktiske side ved det at interviewe over lange afstande og betydningen af at bruge en medieplatform som de unge filmskabere kender

Methodologies for tracking learning paths: designing the online research study Making a Filmmaker

The article concerns the design of a collaborative research project (2008-09) entitled Making a Filmmaker, which examines how young Scandinavian filmmakers create their own learning paths in formal and/or informal contexts. Our interest is in how learning experiences and contexts motivate the young filmmakers: what furthers their interest and/or hinders it, and what learning patterns emerge. The aim of this article is to present and discuss issues regarding the methodology and methods of the study, such as developing a relationship with interviewees when conducting interviews online (using MSN). We suggest two considerations about using online interviews: how the interviewees value the given subject of conversation and their familiarity with being online. The benefit of getting online communication with the young filmmakers is the ease it offers, because it is both practical and appropriates a meeting platform that is familiar to our participants.Artiklen handler om forskningsdesign af et kollaborativt projekt (2008-09), At skabe en filmskaber, som handler om hvordan unge, skandinaviske filmskabere skaber deres egne læringsveje i formelle, semi-formelle og/eller uformelle kontekster. Vores overordnede interesse i projektet er at se på hvordan de unges oplevelser og kontekster påvirker deres læringsprocesser. Målet med denne artikel er at præsentere og diskutere problemstillinger angående vores anvendte metodik og metoder, herunder at udvikle et forhold med informanter via skriftlige online-interviews (med MSN). Vi drøfter både den praktiske side ved det at interviewe over lange afstande og betydningen af at bruge en medieplatform som de unge filmskabere kender

Current advances in digital cognitive assessment for preclinical Alzheimer\u27s disease

There is a pressing need to capture and track subtle cognitive change at the preclinical stage of Alzheimer\u27s disease (AD) rapidly, cost-effectively, and with high sensitivity. Concurrently, the landscape of digital cognitive assessment is rapidly evolving as technology advances, older adult tech-adoption increases, and external events (i.e., COVID-19) necessitate remote digital assessment. Here, we provide a snapshot review of the current state of digital cognitive assessment for preclinical AD including different device platforms/assessment approaches, levels of validation, and implementation challenges. We focus on articles, grants, and recent conference proceedings specifically querying the relationship between digital cognitive assessments and established biomarkers for preclinical AD (e.g., amyloid beta and tau) in clinically normal (CN) individuals. Several digital assessments were identified across platforms (e.g., digital pens, smartphones). Digital assessments varied by intended setting (e.g., remote vs. in-clinic), level of supervision (e.g., self vs. supervised), and device origin (personal vs. study-provided). At least 11 publications characterize digital cognitive assessment against AD biomarkers among CN. First available data demonstrate promising validity of this approach against both conventional assessment methods (moderate to large effect sizes) and relevant biomarkers (predominantly weak to moderate effect sizes). We discuss levels of validation and issues relating to usability, data quality, data protection, and attrition. While still in its infancy, digital cognitive assessment, especially when administered remotely, will undoubtedly play a major future role in screening for and tracking preclinical AD

Multiscale Modeling of Sintering of Hard Metal

In this contribution, we discuss the multiscale modeling of sintering of hard metal, which is composed of hard particles (WC) with a melted binder (Co). Numerical results are shown for a coupled FE2 analysis involving homogenization of the consolidating compact

Text Annotation Handbook: A Practical Guide for Machine Learning Projects

This handbook is a hands-on guide on how to approach text annotation tasks. It provides a gentle introduction to the topic, an overview of theoretical concepts as well as practical advice. The topics covered are mostly technical, but business, ethical and regulatory issues are also touched upon. The focus lies on readability and conciseness rather than completeness and scientific rigor. Experience with annotation and knowledge of machine learning are useful but not required. The document may serve as a primer or reference book for a wide range of professions such as team leaders, project managers, IT architects, software developers and machine learning engineers.Comment: 30 pages, white pape

Demographically adjusted Rey–Osterrieth Complex Figure Test norms in a Swedish and Norwegian cohort aged 49–77 years and comparison with North American norms

Introduction The Rey–Osterrieth Complex Figure Test (RCFT) is one of the most commonly used neuropsychological tests in Sweden and Norway. However, no publications provide normative data for this population. The objective of this study was to present demographically adjusted norms for a Swedish and Norwegian population and to evaluate these in an independent comparison group. Methods The RCFT was administrated to 344 healthy controls recruited from the Swedish Gothenburg MCI study, the Norwegian Dementia Disease Initiation study, and the Swedish Cardiopulmonary Bioimage Study. Age ranged from 49 to 77 years (mean = 62.4 years, SD = 5.0 years), and education ranged from 6 to 24 years (mean = 13.3 years, SD = 3.0 years). Using a regression-based procedure, we investigated the effects of age, sex, and years of education on test performance. We compared and evaluated our Swedish and Norwegian norms with North American norms in an independent comparison group of 145 individuals. Results In healthy controls, age and education were associated with performance on the RCFT. When comparing normative RCFT performance in an independent comparison group, North American norms generally overestimated immediate and delayed recall performance. In contrast, our Swedish and Norwegian norms appear to better take into account factors of age and education. Conclusions We presented demographically adjusted norms for the RCFT in a Swedish and Norwegian sample. This is the first normative study of the RCFT that presents normative data for this population. In addition, we showed that North American norms might produce inaccurate normative estimations in an independent comparison group

Precipitation and separation of lignin from kraft black liquor

The separation of lignin from black liquor is an attractive option to consider for pulp mills. In modern pulp mills, lignin extraction offers the opportunity of withdrawing an energy surplus in the form of a solid biofuel. The introduction of lignin separation can “de-bottleneck” pulp mills in which pulp production is limited by recovery boiler capacity. Separated lignin can be used within the mill, e.g. by replacing fuel oil in the lime kiln or fired in a power boiler, or externally e.g. in CHP plants. Today, only half of the wood material (i.e. the cellulose) is used for the production of valuable products. In a more futuristic perspective, separated lignin can be used as a raw material for the production of “green” chemicals and/or materials replacing oil as a raw material, thus increasing the value created from the wood material. In this thesis, the extraction of lignin in pulp mills, in particular by precipitation from black liquor, was studied with the focus being on quantifying separation properties of the lignin material. After precipitation, the lignin is filtered and washed. Laboratory studies showed that precipitation and filtration is a rather straight-forward process if the right conditions in terms of pH and temperature are used during precipitation. While lignin precipitated from different softwood kraft black liquors taken from the evaporators showed comparable filtration properties, lignin from membrane concentrated black liquors proved to be more difficult to filter. Direct washing of lignin filter cakes proved to be difficult; problems with plugging and uneven washing, in addition to large yield losses, were encountered. These problems were found to be caused by large gradients in pH and ionic strength in the lignin filter cake during washing. A novel washing method was proposed and developed to solve these problems. This process was investigated in laboratory, bench and pilot scale equipment with excellent results in terms of final purity of the lignin product and very low yield losses during separation. Filtration and washing characteristics were quantified and found to be similar in the three different scales that were studied. During the pilot scale trial, more than 8 tonnes of lignin could be produced using the novel separation method, with high levels of purity (<0.5 % w sodium), dry solids content (>60%) and calorific value (LHV 25.4 MJ/kg)

Is it possible to measure blood pressure with photopletysmography in combination with a bio-acoustic sensor?

The aim of the work was to investigate the possibility to combine information from PPG and bio-acoustic technology to extract information that is related to the blood pressure. The measurements have been carried out with several different configurations. First the relation between arterial sounds and the PPG-signal was studied. After those measurements with both PPG and the bio- acoustic technique was concluded on people in different positions and after riding a bike. The goal was to vary the blood pressure. The conclusion that can be drawn in this report is that the bio-acoustic and the PPG-signal in peripheral arteries have the same source. That implies that arterial sounds are a product of turbulence when the pulse wave passes by. Further it can be assumed that it is the first heart sound that is represented in the arterial sounds. The time before and after the arterial sound in one heart cycle vary whit the blood pressure. There relationship seems also to vary with the bloodpressure but it vary differently under different conditions