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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.
11

The geomorphology of Southeast Australian mountain streams

Thompson, Chris J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2006 (has links)
This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.
12

The geomorphology of Southeast Australian mountain streams

Thompson, Chris J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2006 (has links)
This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.
13

The geomorphology of Southeast Australian mountain streams

Thompson, Chris J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2006 (has links)
This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.
14

The geomorphology of Southeast Australian mountain streams

Thompson, Chris J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2006 (has links)
This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.
15

The geomorphology of Southeast Australian mountain streams

Thompson, Chris J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2006 (has links)
This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.
16

Effektivare materialhantering från leveransmottagning till materialanvändning på en byggarbetsplats / Make the material management on a construction site more efficient from delivery to usage

Hallman, Mattias, Elham, Mirwais January 2017 (has links)
Purpose: The problem with the construction industry is inefficient material handling that creates waste in form of unnecessary activities that do not increase the value of the product. The construction industry is accused of production delays, exceedance of budget and difficulties in having a high quality. The aim is to find opportunities for improvements to make the material handling on a construction site at deliveries, material storage and material transports more efficient. Method: A qualitative case study of an organisation was carried out to achieve the aim of the report. The methods used in this study was unstructured observations, semi structured interviews and document analysis. Findings: A checklist for material handling based on the theories of Muda, 5S and JIT within Lean has been designed as an improvement and is intended to be used at a construction site. The checklist is based on the collected empirical study and consists of three parts, based on the issues of the study, which were deliveries, material storage and material transport. The purpose of the checklist is to improve the material handling at a construction site by identifying and eliminating wastes in terms of waiting, transport, storage and defects. Implications: By using the checklist, follow the delivery plan, improve the construction site plan and improve the contract between the suppliers and the company that have been concluded from the study result, waste in deliveries, material storage and material transport can be reduced. The recommendation is to follow the suggestions for improvement to make the material handling more efficient and reduce waste on a construction site. Limitations: The limitations that have been made in the study is to identify the wastes in the material handling moments that have been used in the study during the different material handling processes. The communication between workers, in what way the company plans their work activities, work environment and quality of work is not included in the study. / Syfte: Problemet i byggbranschen är ineffektiv materialhantering som skapar slöserier av resurser i form av onödiga aktiviteter som inte ökar värdet på slutprodukten. Byggnadssektorn anklagas för förseningar, budgetöverskridande och svårigheter att hålla en hög kvalitet. Målet är att hitta förbättringsmöjligheter för att effektivisera materialhantering på en byggarbetsplats vid leveransmottagning, materiallagring och materialförflyttning. Metod: För att uppnå studiens mål har en kvalitativ fallstudie av en organisation genomförts. De datainsamlingsmetoder som har använts är strukturerade observationer, semistrukturerade intervjuer och dokumentanalys. Resultat: En checklista för materialhantering baserad på teorierna Muda, 5S och JIT inom Lean har utformats som ett förbättringsförslag och är tänkt att användas på en byggarbetsplats. Checklistan är gjord utifrån studiens insamlade empiri och består av tre delar som utgår från studiens frågeställningar leveransmottagning, materiallagring och materialförflyttningen. Syftet med checklistan är att effektivisera materialhanteringen på en byggarbetsplats genom att identifiera och eliminera slöserierna i form av väntan, transport, lager och defekter. Konsekvenser: Genom att använda checklistan, följa leveransplanen, uppdatera APD-planen och förbättra kontraktet mellan leverantörer och företag som har framtagits i studiens resultat kan slöserier inom leveransmottagning, materiallagring och materialförflyttning minskas. Rekommendationerna blir att följa förbättringsförslagen för att effektivisera materialhanteringen och reducera slöserier på byggarbetsplatsen. Begränsningar: De avgränsningar som har gjorts i studien är att identifiera de valda slöserier inom Muda som behandlades i studien under olika materialhanteringsmoment. Kommunikationen mellan arbetarna, på vilket sätt företaget jobbar med att planera olika arbetsmoment, arbetsmiljö och arbetskvalitet ingår inte studien.
17

On solving the view selection problem in distributed data warehouse architectures

Lehner, Wolfgang, Bauer, Andreas 02 June 2022 (has links)
The use of materialized views in a data warehouse installation is a common tool to speed up mostly aggregation queries. The problems coming along with materialized aggregate views have triggered a huge variety of proposals, such as picking the optimal set of aggregation combinations, transparently rewriting user queries to take advantage of the summary data, or synchronizing pre-computed summary data as soon as the base data changes. The paper focuses on the problem of view selection in the context of distributed data warehouse architectures. While much research was done with regard to the view selection problem in the central case, we are not aware to any other work discussing the problem of view selection in distributed data warehouse systems. The paper proposes an extension of the concept of an aggregation lattice to capture the distributed semantics. Moreover, we extend a greedy-based selection algorithm based on an adequate cost model for the distributed case. Within a performance study, we finally compare our findings with the approach of applying a selection algorithm locally to each node in a distributed warehouse environment.

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