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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Användningen av BIM-verktyg och Lean-principer för optimerade tidsplaner i byggprojekt : En fallstudie av implementering / The use of BIM tools and Lean principles for optimized schedules in construction projects : A case study of implementation

Alkhatib, Yazeed, Alshammaa, Mohammad January 2023 (has links)
Inom byggbranschen är förseningar i byggprojekts leveranser vanligt förekommande och utgör ett utmanande problem. För att övervinna detta problem krävs en utvecklad och noggranna tidsplaner som följs av alla berörda parter. I dagsläget använder sig byggindustrin huvudsakligen av aktivitetsbaserade tidsplaner, som representeras av Critical Path Method (CPM) och dess Gantt-schema. Trots att en annan tidsplaneringsmetod, baserad på lokalitet, visar lovande potential för att effektivt hantera förseningar i leveranser, har den inte fått samma uppmärksamhet. Line of Balance (LOB) är en metod inom location-based scheduling (LBS), där platsen behandlas som en dimension i produktionsprocessen och den har visat sig vara effektivare alternativ än Gantt-schema. I stället för att endast fokusera på aktiviteter fördelar LOB-metoden aktiviteter på lokaliteter där de ska genomföras, vilket underlättar för alla parter att följa en tydlig plan och övervaka arbeten på ett enklare sätt. BIM-verktyg har visat sig vara effektiva för att förbättra och effektivisera LOB-tidsplaner genom att tillhandahålla specialiserade verktyg som underlättar skapandet av sådana tidsplaner. CPM-metoden utgör grunden för många programvaror som används för att skapa LOB-tidsplaner såsom programmet Vico Office. Dessutom kan användning av BIM-verktyg möjliggör tillämpning av Lean-tänkande som bidrar till att förbättra arbetsflöden och öka kvalitet. Detta arbete undersöker hur tidsplaner påverkas vid övergången från aktivitetsbaserade- till lokalitetsbaserade tidsplaner, med hjälp av BIM-verktyget Vico Office. Vidare undersöks hur tillämpningen av Lean-principer såsom ”Visual Management” och ”Reduced Batch Size” påverkar lokalitetsbaserade tidsplaner. Gantt-schemat som analyserades i detta arbete är specifikt för byggföretaget NCC och omfattar utförandet av Hus A, Hus B och en förskola. Dock var endast detaljerad information om aktiviteterna som ingår i Hus A tillgängliga. För att konvertera Gantt-schemat till en lokalitetsbaserad tidsplan användes aktiviteternas varaktighet och lokaliteter från Gantt-schemat. För aktiviteter som saknade lokaliteter användes logiskt tänkande och erfarenhet för att fördela dem i lämpliga lokaliteter. Dessutom användes byggritningar som tillhandahölls av Karlstads kommunen för att tillämpa Lean-principen ”Reduced Batch Size”. LOB-diagrammet som genereras av Vico:s Schedule Planner är i enlighet med Lean-principen ”Visual Management”. Det har visat en förbättrad förmåga att upptäcka tomma områden, kollisioner och diskontinuerliga aktiviteter jämfört med Gantt-scheman. Dessutom användes Lean-principen ”Reduced Batch Size” för att minska väntetiderna mellan arbetsgrupper. Trots att byggprojektets ledtid överskreds med två veckor, resulterade konverteringen i en lokalitetsbaserad tidsplan som främjade ett kontinuerligt arbetsflöde, en effektivare arbetsrytm och en förbättrad uppföljning av byggprocessen. / In the construction industry, delays in project deliveries are a common occurrence. In order to overcome this problem, a developed and accurate schedule is required which is followed by all parties concerned. Currently, traditional activity-based Gantt charts are primarily used. However, another scheduling method based on location shows promising potential for effectively managing delivery delays but has not received the same attention. Line of Balance (LOB) is a method within location-based scheduling (LBS), where the location is treated as a dimension in the production process, and it has proven to be a more efficient alternative than the Gantt chart. BIM tools, such as Vico Office, have proven effective in improving and streamlining LOB schedules by providing specialized tools that facilitate the creation of such schedules. Additionally, the use of BIM tools can facilitate the application of Lean thinking, which helps improve workflows. This study investigates how schedules are affected by the transition from activity-based to location-based schedules using the BIM tool Vico Office. Furthermore, it examines how the application of Lean principles such as “Visual Management” and “Reduced Batch Size” affect location-based schedules. The Gantt chart analysed in this study belongs to the construction company NCC and contains detailed information on the activities in House A. The LOB diagram generated by Vico's Schedule Planner aligns with the Lean principle of “Visual Management”. It has demonstrated an improved ability to detect empty areas, collisions, and discontinuous activities compared to Gantt charts. Additionally, the Lean principle of “Reduced Batch Size” was utilized to minimize waiting times between work groups. Despite the project exceeding the allotted time by two weeks, the conversion resulted in a location-based schedule that promoted continuous workflow, enhanced efficiency, and improved monitoring of the construction process.
22

Bioelectrical dynamics of the entorhinal cortex

Killian, Nathaniel J 27 August 2014 (has links)
The entorhinal cortex (EC) in the medial temporal lobe plays a critical role in memory formation and is implicated in several neurological diseases including temporal lobe epilepsy and Alzheimer’s disease. Despite the known importance of this brain region, little is known about the normal bioelectrical activity patterns of the EC in awake, behaving primates. In order to develop effective therapies for diseases affecting the EC, we must first understand its normal properties. To contribute to our understanding of the EC, I monitored the activity of individual neurons and populations of neurons in the EC of rhesus macaque monkeys during free-viewing of photographs using electrophysiological techniques. The results of these experiments help to explain how primates can form memories of, and navigate through, the visual world. These experiments revealed neurons in the EC that represent visual space with triangular grid receptive fields and other neurons that prefer to fire near image borders. These properties are similar to those previously described in the rodent EC, but here the neuronal responses relate to viewing of remote space as opposed to representing the physical location of the animal. The representation of visual space may be aided by another EC neuron type that was discovered, free-viewing saccade direction cells, neurons that signaled the direction of upcoming saccades. Such a signal could be used by other cells to prepare to fire according to the future gaze location. Many of these spatially-responsive neurons also represented memory for images, suggesting that they may be useful for associating items with their locations. I also examined the neuronal circuitry of recognition memory for visual stimuli in the EC, and I found that population synchronization within the gamma-band (30-140 Hz) in superficial layers of the EC was modulated by stimulus novelty, while the strength of memory formation modulated gamma-band synchronization in the deep layers and in layer III. Furthermore, the strength of connectivity in the gamma-band between different layers was correlated with the strength of memory formation, with deep to superficial power transfer being correlated with stronger memory formation and superficial to deep transfer correlated with weaker memory formation. These findings support several previous investigations of hippocampal-entorhinal connectivity in the rodent and advance our understanding of the functional circuitry of the medial temporal lobe memory system. Finally, I explored the design of a device that could be used to investigate properties of brain tissue in vitro, potentially aiding in the development of treatments for disorders of the EC and other brain structures. We designed, fabricated, and validated a novel device for long-term maintenance of thick brain slices and 3-dimensional dissociated cell cultures on a perforated multi-electrode array. To date, most electrical recordings of thick tissue preparations have been performed by manually inserting electrode arrays. This work demonstrates a simple and effective solution to this problem by building a culture perfusion chamber around a planar perforated multi-electrode array. By making use of interstitial perfusion, the device maintained the thickness of tissue constructs and improved cellular survival as demonstrated by increased firing rates of perfused slices and 3-D cultures, compared to unperfused controls. To the best of our knowledge, this is the first thick tissue culture device to combine forced interstitial perfusion for long-term tissue maintenance and an integrated multi-electrode array for electrical recording and stimulation.
23

Evaluation and Comparison of Project Scheduling Methods and Software Used in the Construction Industry

Parlak, Mehmet 12 August 2016 (has links)
The objectives of this thesis are to evaluate scheduling methods and most common construction project management software (CPMS) which are Primavera and MS Project, and to determine most widely used project scheduling techniques and CPMS with a survey. The thesis focus on project scheduling since it is very deterministic for project success. Evaluation results indicate that, Gantt Chart Method and PDM are useful for small to medium projects, CPM is for complex projects, PERT is for uncertain projects, and LOB Technique is for repetitive projects. The comparison between Primavera and MS Project show that Primavera is more robust, professional, and detailed while MS Project is cheaper and easier. The survey was completed with 22 participants from construction companies in the US and Turkey and the results demonstrate CPM and Gantt Chart Method are the most common methods. Also, MS Project is the most widely used CPMS followed by the Primavera.

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