Younger students’ difficulties regarding the analogue clock: an interview study in grades 2–3

För att på ett fördjupat sätt förstå innebörden i olika svårigheter som elever i årskurs 2–3 kan ha gällande tidsavläsning från den analoga klockan är detta en intervjustudie med sju elever som besvarar frågeställningen: vad urskiljer/urskiljer inte eleverna när de löser olika uppgifter som handlar om att avläsa tid från den analoga klockan? Som teoretisk utgångspunkt används variationsteorin då dess olika begrepp är centrala för att förstå hur en annan person uppfattar ett specifikt ämnesinnehåll. I resultatet redovisas de olika aspekter av innehållet kring tidsavläsning från den analoga klockan som eleverna urskilt eller inte urskilt som i sin tur leder till att olika svårigheter identifieras. Vidare diskuteras studiens styrkor och svagheter i relation till metodval samt hur resultatet förhåller sig till tidigare forskning, styrdokument och yrkesverksamheten. Sammanfattningsvis framgår det ur resultatet att en övergripande svårighet har att göra med att eleverna inte urskilt att klockan är uppbyggd på 60 minuter och till stor del förlitar sig på minnesassociationer vid avläsning av minutvisaren.This is an interview study with seven students. To understand the deeper meaning of various difficulties that students in grades 2–3 may have regarding time telling on the analogue clock this study answers the question: what does the students discern/not discern when they solve different tasks involving time telling on the analogue clock? As a theoretical framework, the variation theory is used as its various concepts are central to understand how another person perceives a specific curriculum content. The result shows the different aspects of the content, regarding time telling on the analogue clock, that the students did discern or did not discern, which in turn leads to the identification of various difficulties. Furthermore, a discussion is being held regarding the strengths and weaknesses in relation to the chosen method as well as how the result relates to previous research, curriculum documents and the profession of education. In summary, it is clear from the result that an overall difficulty has to do with the students not discerning that the clock is built up in 60 minutes and largely relies on memory associations when reading the minute hand

Teaching about the analogue clock and digital clock : A litterature study

Syftet med denna litteraturstudie är att ge en bild av hur matematikdidaktisk forskning beskriver elevers förståelse för den analoga respektive digitala klockan i grundskolans tidigare år. För att ta reda på detta kommer följande frågeställningar användas: vilka svårigheter och missuppfattningar kan elever visa i sin förståelse för den analoga respektive digitala klockan? Vilka arbetssätt och metoder har visat sig kunna utveckla elevers lärande om klockan i undervisning? Studien har baserats på vetenskapliga artiklar som funnits via en systematisk sökprocess i olika databaser och kedjesökning. I studien konstateras att forskare lyfter fram olika arbetsmetoder i undervisning rörande klockan, men även likheter finns. Vi har sett att elevers mognad spelar en viktig roll när det kommer till undervisning om klockan, men hur undervisningen ska bedrivas kan dock se olika ut. Vi presenterar även forskarnas syn på vilka vanliga svårigheter och missuppfattningar som elever kan visa när de ställs inför analog eller digital representation av tid. Exempelvis är timvisaren och minutvisaren något som elever vanligtvis har svårt att särskilja. Vidare är forskarna eniga om att elever har lättare att förstå och avläsa den digitala klockan jämfört med den analoga

Simulation of Sheet Metal Forming using Elastic Stamping Dies

Simulation of sheet metal forming is one of the major applications of LS-DYNA. Today, a majority of the forming industry is using Finite Element models to design the stamping dies in order to prevent excessive thinning, wrinkling and producing parts within tolerance by compensating for springback deformation. All these simulations are made using the assumption of rigid forming surfaces. Depending on the type of press, tool design and sheet metal part, this assumption could prove to be incorrect which yields a forming result that depends on the elastic deformation of the stamping die and in some cases the entire stamping press. Such deformations are usually compensated during die try-out by manual rework which is costly and time consuming. This paper presents the result of a study performed at Volvo Cars press shop in Olofström, Sweden, aiming at determining computational methods to introduce elastic stamping dies in the sheet metal forming simulations in order to minimize manual rework by performing a virtual tryout of the stamping die. The methodology to model the stamping die and the forming surfaces in LS-DYNA are presented and a simulation model is gradually improved from using nominal rigid CAD surfaces through scanned tool surfaces and finishing with an elastic model of the stamping die assembly. The part used in the study is the side door inner for Volvo XC90 and comparisons are continuously made between simulations results and measurements on parts from running production

Increased Temperature and Discharge Influence Overwinter Growth and Survival of Juvenile Salmonids in a Hydropeaking River: Simulating Effects of Climate Change Using Individual-Based Modelling

Climate change causes warming of rivers and may increase discharge, particularly during winter. Downstream of hydropower plants, fluctuating water temperature and flow create dynamic overwintering conditions for juvenile salmonids. We used inSTREAM 7.2-SD to simulate the effects of increased temperature (+2 °C) and discharge (+10%) on the overwinter growth and mortality of one-summer- and two-summer-old Atlantic salmon and brown trout in a river with a hydropeaking flow regime in a 2 × 2 design with replicated simulations. Water temperature had a major positive relationship with growth for both species and year classes, whereas increased flow alone had no major general effect on overwinter growth. For one-summer-old trout experiencing the high temperature regime, however, increased flow resulted in reduced growth. There were no major effects from temperature and flow on the survival rate of the two-summer-old fishes. On the other hand, there were significant interaction effects for the one-summer-olds, indicating that the effect of flow depended on temperature. For one-summer-old salmon, high flow resulted in increased survival in the low temperature regime, whereas it resulted in reduced survival in high temperature. In contrast, for one-summer-old trout, high flow resulted in reduced survival in the low temperature regime and increased survival in the high temperature. Different hydropower operation alternatives may interact with warming, affecting the relative competitive abilities of stream salmonids. Ecological models that predict the effects of different environmental conditions, such as temperature and flow regimes, may offer insight into such effects when in situ experiments are not feasible

An overview of Methods for Simulating Sheet Metal Forming with Elastic Dies

Sheet metal forming (SMF) simulations are traditionally carried out with rigid active forming surfaces. This means that the elasticity and dynamics of presses and die structures are ignored. The only geometries of the tools included in the simulations are the active forming surfaces. One reason for this simplification is the large amount of computational power that is required to solve finite element (FE) models that incorporates elastic stamping dies. Another reason is the lack of die CAD models before the later stages of stamping projects. Research during the last couple of decades indicated potential large benefits when including elastic dies in SMF simulations. For example, for simulating die try-out or for Digital Twins of presses and dies. Even though the need and potential benefits of elastic dies in simulations are well known it is not yet implemented on a wide scale. The main obstacles have been lacking data on presses and dies, long simulation times, and no standardized implementation in SMF software. This paper presents an overview of existing methods for SMF simulations with elastic dies and discuss their respective benefits and drawbacks. The survey of methods shows that simulation models with elastic tools will be needed for detailed analyses of forming operations and also for purposes like digital twins. On the other hand, simplified and robust models can be developed for non-FEA users to carry out simple one-step compensation of tool surfaces for virtual spotting purposes. The most promising and versatile method from the literature is selected, modified, and demonstrated for industrial sized dies.Eureka Smart Cambe

Three Industrial Cases of Sheet Metal Forming Simulations with Elastic Dies

Previous research and experience points to many advantages if sheet metal forming is simulated with elastic dies. Some areas that are enabled by simulations with elastic dies are virtual spotting, improved digital twins, and improved production support. A promising method was selected from the literature, and after important modifications it is deemed to be fast and robust for simulating industrial sized dies. The method consists of meshing die solids with a coarse mesh to represent the structural behaviour of the die. The forming surfaces are then represented by a fine shell mesh connected to the solid mesh by tied contacts with an offset. With additional modifications to reduce solver time this yields a robust and flexible way of modelling sheet metal forming with elastic dies. There is an increase in preprocessing and simulation time compared to using rigid tools, but industrial dies can now be modeled within an hour and solved within a working day. It is also easy to update the model by replacing separate parts such as die solids or forming surfaces. One of the main criteria in favor of the selected approach is the realistic modeling of blankholder and cushion systems. In this paper simulations of three industrial cases are demonstrated: one case of virtual die spotting and two cases of production support. The three cases demonstrate the importance and potential of using elastic dies during virtual die tryout, production support, and for cases like digital twins and production control.Eureka Smart Cambe

Distinct patterns of brain activity characterise lexical activation and competition in spoken word production

Contains fulltext : 126491.pdf (publisher's version ) (Open Access)According to a prominent theory of language production, concepts activate multiple associated words in memory, which enter into competition for selection. However, only a few electrophysiological studies have identified brain responses reflecting competition. Here, we report a magnetoencephalography study in which the activation of competing words was manipulated by presenting pictures (e.g., dog) with distractor words. The distractor and picture name were semantically related (cat), unrelated (pin), or identical (dog). Related distractors are stronger competitors to the picture name because they receive additional activation from the picture relative to other distractors. Picture naming times were longer with related than unrelated and identical distractors. Phase-locked and non-phase-locked activity were distinct but temporally related. Phase-locked activity in left temporal cortex, peaking at 400 ms, was larger on unrelated than related and identical trials, suggesting differential activation of alternative words by the picture-word stimuli. Non-phase-locked activity between roughly 350-650 ms (4-10 Hz) in left superior frontal gyrus was larger on related than unrelated and identical trials, suggesting differential resolution of the competition among the alternatives, as reflected in the naming times. These findings characterise distinct patterns of activity associated with lexical activation and competition, supporting the theory that words are selected by competition.11 p

Venous Thromboembolism During Treatment with Antipsychotics: A Review of Current Evidence

This article summarises the current evidence on the risk of venous thromboembolism (VTE) with the use of antipsychotics. An increasing number of observational studies indicate an elevated risk of VTE in antipsychotic drug users. Although the use of certain antipsychotics has been associated with VTE, current data can neither conclusively verify differences in occurrence rates of VTE between first- and second-generation antipsychotics or between individual compounds, nor identify which antipsychotic drugs have the lowest risk of VTE. The biological mechanisms involved in the pathogenesis of this adverse drug reaction are still to be clarified but hypotheses such as drug-induced sedation, obesity, increased levels of antiphospholipid antibodies, enhanced platelet aggregation, hyperhomocysteinaemia and hyperprolactinaemia have been suggested. Risk factors associated with the underlying psychiatric disorder may at least partly explain the increased risk. Physicians should be aware of this potentially serious and even sometimes fatal adverse drug reaction and should consider discontinuing or switching the antipsychotic treatment in patients experiencing a VTE. Even though supporting evidence is limited, prophylactic antithrombotic treatment should be considered in risk situations for VTE