177 research outputs found
Topographic, Hydraulic, and Vegetative Controls on Bar and Island Development in Mixed BedrockâAlluvial, Multichanneled, Dryland Rivers
We investigate processes of bedrockâcore bar and island development in a bedrockâinfluenced anastomosed reach of the Sabie River, Kruger National Park (KNP), eastern South Africa. For sites subject to alluvial stripping during an extreme flood event (~4470â5630 m3 sâ1) in 2012, preâ and postâflood aerial photographs and LiDAR data, 2D morphodynamic simulations, and field observations reveal that the thickest surviving alluvial deposits tend to be located over bedrock topographic lows. At a simulated peak discharge (~4500 m3 sâ1), most sediment (sand, fine gravel) is mobile but localized deposition on bedrock topographic highs is possible. At lower simulated discharges (<1000 m3 sâ1), topographic highs are not submerged, and deposition occurs in lower elevation areas, particularly in areas disconnected from the main channels during falling stage. Field observations suggest that in addition to discharge, rainwash between floods may redistribute sediments from bedrock topographic highs to lower elevation areas, and also highlight the critical role of vegetation colonization in bar stability, and in trapping of additional sediment and organics. These findings challenge the assumptions of preferential deposition on topographic highs that underpin previous analyses of KNP river dynamics, and are synthesized in a new conceptual model that demonstrates how initial bedrock topographic lows become topographic highs (bedrock coreâbars and islands) in the latter stages of sediment accumulation. The model provides particular insight into the development of mixed bedrockâalluvial anastomosing along the KNP rivers, but similar processes of bar/island development likely occur along numerous other bedrockâinfluenced rivers across dryland southern Africa and farther afield
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The micromorphology of glaciolacustrine varve sediments and their use for reconstructing palaeoglaciological and palaeoenvironmental change
Former glaciolacustrine systems are an important archive of palaeoglaciological, palaeoenvironmental and palaeoclimatic change. The annually laminated (varved) sediments that, under certain conditions, accumulate in former glacial lakes, offer a rare opportunity to reconstruct such changes (e.g. glacier advance and retreat cycles, glacier ablation trends, permafrost melt, nival events) at annual or even sub-annual temporal resolution. Data of this kind are desirable for their ability to guide and test numerical model simulations of glacier dynamics and palaeoclimatic change that occur over rapid time intervals, with implications for predicting future glacier response to climatic change, or the effects of weather and climate events on lake sedimentation. The most valuable records preserved in glaciolacustrine systems are continuous varved sequences formed in the distal parts of glacial lakes, where microscale lamination structures can accumulate relatively undisturbed. Technological advances, in the last few decades, have enabled improved characterisation of glaciolacustrine varve microfacies and the precise measurement of varve thickness at the micrometre scale. However, unlike in cognate fields (e.g. soil science), protocols for the robust and consistent description and interpretation of glaciolacustrine varve sediments are lacking. To fill this gap, and to provide a resource for future studies of glaciolacustrine varved sediments, this paper reviews the processes of sedimentation in glacial lake basins, and presents the defining microfacies characteristics of glacial varves using a descriptive protocol that uses consistent examination of grain size, sorting, structure, nature of contacts, development of plasmic fabrics and features such as dropgrains and intraclasts within individual laminations. These lamination types are then combined into lamination sets, whose structures can be interpreted as glaciolacustrine varves. Within this framework, we define five principal assemblages of glaciolacustrine varve microfacies which, if clearly identified in palaeoglaciolacustrine settings, enable more detailed palaeoenvironmental interpretations to be made. Finally, we discuss the utility and complexities of reconstructing the evolution of former glacial lake systems using varve microfacies and thickness datasets
Controls on tidal sedimentation and preservation : Insights from numerical tidal modelling in the Late OligoceneâMiocene South China Sea, Southeast Asia
Numerical tidal modelling, when integrated with other geological datasets, can significantly inform the analysis of physical sedimentation processes and the depositional and preservational record of ancient tide-influenced shorelineâshelf systems. This is illustrated in the OligoâMiocene of the South China Sea (SCS), which experienced significant changes in basin physiography and where tide-influenced, shorelineâshelf deposition is preserved in ca 10 sub-basins. Palaeogeographic reconstructions, palaeotidal modelling and regional sedimentary facies analysis have been integrated in order to evaluate the spatialâtemporal evolution and physiographic controls on tidal sedimentation and preservation during the ca 25 Myr OligoâMiocene record in the SCS. Palaeotidal modelling, using an astronomically forced and global tidal model (Fluidity) at a maximum 10 km resolution, indicates that spring tides along Late OligoceneâMiddle Miocene coastlines were predominantly mesotidalâ macrotidal and capable of transporting sand, which reflects two main conditions: (1) increased tidal inflow through wider ocean connections to the Pacific Ocean; and (2) tidal amplification resulting from constriction of the tidal wave in a âblind gulfâ type of basin morphology. Since the MiddleâLate Miocene, a reduction in the amplitude and strength of tides in the SCS was mainly due to diminishing tidal inflow from the Pacific Ocean caused by the northward movement of the Philippines and Izu-Bonin-Mariana arc. Sensitivity tests to palaeogeographic and palaeobathymetric uncertainty indicate that regionalâscale (100â1000s 29 km) palaeogeographic changes influencing tidal inflow versus outflow can override local30 scale (1â100s km) changes to tidal resonance and convergence effects (funnelling and shoaling), such as shelf width and shoreline geometry. Palaeotidal model results compare favourably to the distribution and sedimentary fabric of OligoâMiocene, tide-influenced, shorelineâshelf successions in peripheral SCS basins. However, the preservation potential of tidal deposits is lower in open coastline environments, probably due to enhanced reworking during storms and river floods
Individanpassad undervisning : Hinder och utmaningar utifraÌn ett ramfaktorteoretiskt perspektiv
Syftet med undersoÌkningen var att med bakgrund i en ramfaktorteoretisk ansats studera vad nio laÌrare paÌ gymnasienivaÌ tycker om moÌjligheterna och foÌrutsaÌttningarna att kunna bedriva individanpassad undervisning i skolan, framfoÌrallt med fokus paÌ formativ bedoÌmning. De ramfaktorer som valdes att studera roÌrde framfoÌrallt laÌroplanens innehaÌll, gruppsammansaÌtt- ningen, gruppstorlek och foÌrutsaÌttningar med avseende paÌ tid till undervisning. Studiens undersoÌkningsmetod har varit semistukturerade intervjuer med nio legitimerade gymnasielaÌrare och resultatet i studien aÌr uppbygd kring en tematisk analys kring studiens fraÌgestaÌllning; Vilka hinder finns foÌr att bedriva individanpassad undervisning? Hur loÌser laÌ- rare dessa hinder? VarfoÌr uppstaÌr dessa hinder? Finns det moÌjligheter att foÌrbaÌttra laÌrares ramvillkor? Studien visar paÌ att laÌrare tycker att det finns stora svaÌrigheter att jobba efter de foÌrutsaÌttning- ar som nu erbjuds i skolan i relation till de krav fraÌn laÌroplanen som finns foÌr att bedriva en individanpassad undervisning. De framhaÌver framfoÌrallt en vilja att faÌ baÌttre foÌrutsaÌttningar eller mer avsatt tid foÌr att kunna fokusera stoÌrre del av arbetet i skolan mot arbetet med for- mativ bedoÌmning
Konsumentens val av fastighetsmÀklare
Titel: Konsumentens val av fastighetsmĂ€klare Ămne: Kandidatuppsats i företagsekonomi. Författare: Elin Hjulström Nyckelord: Marknadsföring, relationer, tjĂ€nst, lojalitet, fastighetsmĂ€klare. Problemformulering: Vilka kriterier anser smĂ„hussĂ€ljare pĂ„verkar deras val av fastighetsmĂ€klare och vilka av dem Ă€r avgörande i valet? Hur ska fastighetsmĂ€klaren agera i och inför en fastighetsaffĂ€r för att skapa förtroende och för att fĂ„ kunden att Ă„terkomma? Syfte: Att beskriva vilka kriterier som Ă€r viktiga och avgörande nĂ€r en bostadssĂ€ljare vĂ€ljer fastighetsmĂ€klare. Teori: Som utgĂ„ngspunkt anvĂ€nds en modell över tjĂ€nstemarknadsföringsprocessen. Teori behandlas kring de olika stegen i modellen; önskemĂ„l och behov, utveckla och kommunicera tjĂ€nsterbjudandet, kundens förvĂ€ntningar, kundmötet samt skapandet av kvalitet och lojalitet. Metod: Kvalitativa intervjuer har genomförts med fem konsumenter som nyligen har anlitat en mĂ€klare. Respondenterna har relativt fritt fĂ„tt berĂ€tta om deras val av fastighetsmĂ€klare samt om hur de anser att processen har fortlöpt. Slutsats: Tre faktorer har visat sig vara avgörande i valet av fastighetsmĂ€klare. Den första Ă€r förtroende för mĂ€klaren som person framför allt men att mĂ€klarfirmans rykte och image speglar seriositet spelar ocksĂ„ en stor roll. Den andra gĂ€ller personkemin mellan sĂ€ljaren och fastighetsmĂ€klaren. De mĂ„ste trivas tillsammans och det mĂ„ste fungera att arbeta tillsammans under den period som försĂ€ljningen tar. Den tredje Ă€r fastighetsmĂ€klarens bemötande mot kunden, att mĂ€klaren upptrĂ€der professionellt och har förstĂ„else för kundens behov. MĂ€klaren ska vara engagerad och hela tiden hĂ„lla sĂ€ljaren uppdaterad och informerad om vad som hĂ€nder i affĂ€ren. Till skillnad frĂ„n tidigare studier pĂ„ omrĂ„det har Ă€ven hĂ„rde vĂ€rden som arvodets storlek och tjĂ€nstens innehĂ„ll visat sig ha betydelse
Autonomous agents in Industry 4.0 : A self-optimizing approach for automated guided vehicles in Industry 4.0 environments
Automated guided vehicles are an integral part of industrial production today. They are moving products to and from shelves in storage warehouses and fetching tools between different workstations in factories. These robots usually follow strict pre-determined paths and are not good at adapting to changes in the environment. Technologies like artificial intelligence and machine learning are currently being implemented in industrial production, a part of what is called Industry 4.0, with the aim of increasing efficiency and automation. Industry 4.0 is also characterized by more connected factory environments, where objects communicate their status, location, and other relevant information to their surroundings. Automated guided vehicles can take advantage of these technologies and can benefit from self-optimizing approaches for better navigation and increased flexibility. Reinforcement learning is used in this project to teach automated guided vehicles to move objects around in an Industry 4.0 warehouse environment. A 10x10 grid world with numerous object destinations, charging stations and agents is created for evaluation purposes. The results show that the agents are able to learn to take efficient routes by balancing the need to finish tasks as fast as possible and recharge their batteries when needed. The agents successfully complete all tasks without running out of battery or colliding with objects in the environment. The result is a demonstration of how reinforcement learning can be applied to automated guided vehicles in Industry 4.0 environments.Automatiserade styrda fordon Àr en integrerad del av dagens industriproduktion. De flyttar produkter till och frÄn hyllor i lagerlokaler och hÀmtar verktyg mellan olika arbetsstationer i fabriker. Dessa robotar följer vanligtvis strikta förutbestÀmda vÀgar och Àr inte bra pÄ att anpassa sig till förÀndringar i miljön. Teknik som artificiell intelligens och maskininlÀrning implementeras just nu i industriproduktion, en del av det som kallas Industri 4.0, i syfte om ökad effektivitet och automatisering. Industri 4.0 kÀnnetecknas ocksÄ av mer uppkopplade fabriksmiljöer, dÀr objekt kommunicerar sin status, plats och annan relevant information till sin omgivning. Automatiserade styrda fordon kan utnyttja de hÀr teknikerna och kan dra nytta av sjÀlvoptimerande metoder för bÀttre navigering och ökad flexibilitet. FörstÀrkningsinlÀrning anvÀnds i detta projekt för att lÀra automatiserade styrda fordon att flytta runt föremÄl i en Industri 4.0 lagermiljö. En 10x10 stor rut-vÀrld med flertalet destinationer, laddningsstationer och agenter skapas i utvÀrderingssyfte. Resultaten visar att agenterna kan lÀra sig att ta effektiva vÀgar genom att balansera behovet av att slutföra sina uppgifter sÄ fort som möjligt och ladda upp sina batterier nÀr det behövs. Agenterna slutför framgÄngsrikt sina uppgifter utan att fÄ slut pÄ batteri eller att kollidera med föremÄl i miljön. Resultatet Àr en demonstration av hur förstÀrkningsinlÀrning kan tillÀmpas pÄ automatiserade styrda fordon i Industri 4.0-miljöer
School - A good place for learning, but maybe not for making mistakes : Students' perceptions of formative assessment and feedback
The purpose of the study was to examine seven upper-secondary school students' perceptions of teachers' use of formative assessment and feedback in the classroom. The basis for the study was Wiliam (2017) and Hattie's (2008) theories on formative assessment and visible learning. The study was conducted using semi-structured interviews with seven students from six different schools to find out what their perceptions were about the use of formative assessment in the school environment. The interviews were analyzed using thematic analysis. The results of the study show that most students experience a fear of failure in their studies. More specifically, the students reported that they had difficulty understanding and using the teachersâ feedback and that this feedback was often perceived as negative. They also find it difficult to interpret what the teacher wants to say with their feedback and they do not dare to challenge themselves in the tasks they are given by teachers due to the fear of making mistakes. There are challenges in how teachers give students feedback and also how feedback is used by students. Mostly the challenge concerns the time it takes for students to get feedback from their teachers, also the difficulty for teachers and students to work formatively with learning platforms. The students reported that learning platforms risk acting more as a way for students to see what level they are reaching in courses, rather than helping students to develop
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