Thèses : « Downstream changes »

1

Beck, Julia S. (Julia Samantha). « Downstream changes in river morphology as a result of dam developments ». Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52243.

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Thesis (MEng)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: A dam can have a significant impact on the downstream river morphology by altering both the flow regime and the sediment load. The effect of a dam is dependent on factors such as the storage capacity relative to the mean annual runoff (MAR), the operation of the reservoir and the sediment yield of the catchment. Changes in the river morphology include the degradation and coarsening of the riverbed, generally closer to the dam, and aggradation further downstream where the sediment delivered by tributaries cannot be carried through because of the reduced sediment transport capacity of the river. The impact of a dam can stretch over several hundreds of kilometres. The main objective of this thesis was to gain a better understanding of the impacts that dams can have on the downstream river morphology. This was done by developing equations that can describe the channel geometry, investigating the effect of the presence of clay and silt on the sediment transport behaviour of sediments, as well as detailed evaluation of simulations carried out with a one-dimensional mathematical river model (MIKE 11). The calibrated regime equations were found to be comparable to other internationally developed regime equations and to be suitable for natural rivers. It was found, however, that these regime equations are not applicable to rivers downstream of dams that have highly unnatural release patterns. Further research is needed in this regard. By investigating the effect of cohesive sediments on the sediment transport behaviour of mixed sediments it was found that as little as 7% clay and silt in the bed could affect their sediment transport characteristics. A methodology was also developed by which the critical conditions for mass erosion of cohesive sediments can be described in terms of the applied stream power. Sediment transport equations were calibrated and verified in terms of the unit input stream power for fine and non-cohesivesediments. The sediment transport equation for fine sediments was implemented in MIKE 11. The simulations over a 40 km reach of the Pongola River downstream of Pongolapoort Dam, have shown that even when a large demand is placed on the stored water, and most of the smaller floods are therefore absorbed by the dam, the downstream impact can still be considerable, with as much as 5 m deep erosion in places. The sediment loads are generally reduced (by as much as 35%), but the effective catchment area downstream of the dam has been reduced by as much as 90%, indicating that substantial erosion had to have taken place in the river. Coarsening of the riverbed was also observed during the simulations.
AFRIKAANSE OPSOMMING: 'n Dam kan 'n aansienlike impak he op die riviermorfologie stroomaf daarvan, deurdat dit beide die vloei en sedimentlading drasties kan verander. Die effek van 'n dam hang van verskeie faktore af, soos die opgaarkapasiteit in vergelyking met die gemiddelde jaarlikse afloop (GJA), die bestuur van die dam en die sedimentlewering van die opvanggebied. Veranderings in die riviermorfologie behels die degradering van die rivierbed, sowel as die uitspoel van fyn materiaal uit die rivierbed, veral nader aan die dam. Deponering vind verder stroomaf van die dam plaas, waar die sediment wat deur die sytakke ingevoer word nie deurgevoer kan word nie, weens die verlaagde sedimentdravermoe van die rivier. Sodoende kan rivierlope oor honderde kilometers deur 'n dam bemvloed word. Die hoofdoel van die tesis was om meer insig te verkry oor die impak wat damme op die stroomaf riviermorfologie kan he. Derhalwe is vergelykings ontwikkel wat die riviermorfologie kan beskryf. Die effek van die teenwoordigheid van klei en slik op die sedimentvervoer-eienskappe is ondersoek, en gedetaileerde ontledings is met 'n een-dimensionele wiskundige riviermodel (MIKE 11) is gedoen. Daar is bevind dat die regime-formules goed vergelyk met ander intemasionaalontwikkelde formules en dat hulle geskik is vir toepassing op natuurlike riviere. Daar is egter gevind dat die formules nie geskik is vir riviere wat stroomaf Ie van damme wat hoogs onnatuurlike loslatings het nie. Verdere navorsing is op hierdie gebied nodig. Ondersoek na die effek wat klei en slik op die sedimentdravermoe het, het getoon dat slegs 7% klei en slik in die rivierbed die sedimentvervoer-eienskappe van mengsels van fyn en growwe materiaal kan bemvloed. 'n Metode is ontwikkel waarmee die kritiese toestande vir massa-erosie van kohesiewe sediment beskryfkan word in terme van die aangewende stroomdrywing teen die bed. 'n Sedimentvervoer-vergelyking in terme van die eenheids-insetstroomdrywing vir fyn en nie-kohesiewe sedimente is gekalibreer en geverifieer. Die nuwe sedimentvervoer-vergelyking vir fyn sedimente is gebruik in die MIKE 11 simulasies. Hierdie simulasies oor 'n 40 km loop van die Pongolarivier stroomaf van Pongolapoort Dam, het getoon dat selfs as daar 'n groot aanvraag op 'n dam se water geplaas word, en gevolglik meeste van die kleiner vloede deur die dam geabsorbeer word, die impak van die dam nogs steeds aansienlik kan wees, met soveel as 5 m diep uitskuring in plekke. Die sedimentladings het gewoonlik verminder (met soveel as 35%), maar die die effektiewe opvanggebiedarea stroomafvan die dam het met meer as 90% verminder, wat daarop dui dat daar aansienlike erodering in die rivier plaasgevind het. Die simulasies het ook getoon dat die hoeveelheid fyn materiaal in die rivierbed verminder het.

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Chouikhi, S. M. « Mass transfer downstream of abrupt changes of duct diameter in two-phase flow ». Thesis, University of Exeter, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354027.

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Hamiton, Jorene Lynn. « Hydrologic and morphologic changes of the West Branch Delaware River, New York, downstream of the Cannonsville Dam ». Diss., Online access via UMI:, 2007.

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Pamidiboina, Venu [Verfasser], et Rudolf Maria [Akademischer Betreuer] Huber. « Molecular changes in EGFR downstream signalling and intracellular calcium changes associated with the cisplatin-resistant phenotype of lung cancer cells / Venu Pamidiboina ; Betreuer : Rudolf Maria Huber ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1216417822/34.

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LIMONCELLI, MARTA. « Short-term erosion pattern in the Alps-Apennines belt constrained by downstream changes of zircons morphology and U-PB ages from the Po drainage modern sands ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/29393.

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Downstream changes of the geochronological signature in the Po drainage allow to assess the relative sediment contributions shed from the orogenic source areas, in order to constrain the short-term (102-104 y) erosion pattern in the Alps-Apennines orogenic couple. In this perspective, we collected modern sands in selected tributaries draining the major tectonic units exposed in the orogen, as well as along the Po River trunk and in different sites of the Po Delta. Zircon concentrates were separated according to specific quantitative procedures coupled with grain-size and grain-density analyses, which provide an evaluation of zircon content in source rocks, of hydraulic sorting effects, and related intersample/intrasample zircon variability. Our methodological approach allows to perform sediment budgets and evaluate mineral content in diverse sediment sources (mineral fertility). Budget calculations were performed by investigating geochronological signals upstream and downstream of major confluences. We employed, LA-ICPMS U-Pb geochronology on detrital zircons, because this technique allows a full control of zircon populations during separation procedures and data analysis; we found, instead, that fission track dating on detrital zircon is affected and biased by selective grain loss. Results of U-Pb analysis performed on single grains show that all samples from the Po Delta yield similar grain-age distributions, and include grain-age populations that are rather constant both in age and size. Major peaks are found at ca. 30 Ma, ca. 280 Ma, and 400-500 Ma. Peaks in these distributions can be traced upstream up to their sources. The bulk of the geochronological signature of the Po Delta sands is displayed already upstream of the confluence of the Northern Apennines rivers, suggesting that short-term erosion rates were much lower in the Northern Apennine than in the Western and Central Alps. Age peaks typical of the eastern Lepontine dome also characterize the Apenninic tributaries, reflecting Oligo-Miocene sedimentary transfer from the Central Alps to the Adriatic foredeep, and next tectonic accretion of turbidite wedges to the Apennine belt. U-Pb analyses were complemented by zircon typology of the whole dataset, integrated by SEM observations on selected samples. Major typological groups can be traced from entry points in the Po Plain down to the Po Delta. Euhedral zircons are largely shed from the External Massifs (Mont Blanc and Argentera) and the Periadriatic plutons. Zircon grains showing signs of chemical abrasion, possibly acquired under high-grade metamorphic conditions, were detected in tributaries draining the Lepontine area.

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Gregorio, Michael Anthony. « Geomorphic Effects of the Hocking River Channelization at Athens, Ohio, on the Downstream Planform ». Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1213210389.

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Rowe, William Jason. « AN INVESTIGATION INTO THE UNINTENDED CONSEQUENCES OF DOWNSTREAM CHANNEL ALLOWANCES ». UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/9.

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Downstream channel allowances involve the practice of selling firms making payments to customers in exchange for distribution of a product. Such transactions occur most frequently in a business-to-business exchange. Although various forms of channel allowances have been investigated over the past three decades, the literature is lacking in guidance regarding whether or not, and to what extent, the salesperson should control these payments. Relying on the theoretical underpinnings of cognitive evaluation theory, this dissertation takes the initial step in understanding the effects of customer perceptions of salesperson control over allowances, with special attention to the impact on the customer-salesperson relationship. A key finding of this study is that high perceived salesperson control (from the customer‘s perspective) has moderation effects in relation to customer loyalty and salesperson performance. An explanation is offered for the unexpected findings followed by a discussion of the implications for theory, managers, and future research in the area of channel allowances.

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Winterhalt, Lesley Marie. « Physical habitat below a hydropeaking dam : examining progressive downstream change ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54407.

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This study examines the short-term physical habitat conditions at four sites on the Kananaskis River, Alberta, where a hydropeaking dam was installed in 1955. This dam imposes both the approximate pre-dam minimum flow, and the pre-dam flood (from a small flood year) on a daily basis. The purpose of this study was to examine the extent of daily changes in physical habitat conditions that organisms in the stream would have to endure, and the extent to which these fluctuations might be reduced downstream due to distance from the dam and unregulated tributary influence. Physical habitat conditions monitored over low flow and high flow dam releases were: velocity; depth; bed mobility; ramping rates; and total suspended solids. River2D was used to calculate weighted usable area and potential habitat for Brown Trout (fry, juveniles and adults) and Mountain Whitefish (fry, juveniles and adults) at the low and high flow conditions. Of the factors examined, only ramping rates and total suspended solids showed signs of downstream attenuation. Differences in depth, velocity, weighted usable area, and potential habitat between low flow and high flow dam releases were variable, and showed no downstream pattern. Between low and high flow releases, significant (p = 0.05) changes in depth were observed at all sites, and significant changes (p = 0.05) in velocity were observed at all but the second site. The second site also saw the smallest changes in measures of habitat between low flow and high flow dam releases; however, all other sites saw median differences of 48.1% to 170.9%. Percent differences in habitat between low and high flow dam releases ranged from 2.6% (second downstream site, juvenile Brown Trout) to 193.3% (third downstream site, adult Mountain Whitefish). These habitat changes happen more often than before the dam was installed (many times weekly vs. about once a year during the spring freshet) and they occur more rapidly. Because these changes happen at times of the year that are out of synchronization with the biota of the river, and as these changes are extreme, this implies challenging physical habitat conditions for indigenous stream biota.
Arts, Faculty of
Geography, Department of
Graduate

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Couperthwaite, John S. « Downstream change in channel hydraulics along the River Severn, UK ». Thesis, University of Birmingham, 1997. http://etheses.bham.ac.uk//id/eprint/702/.

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An understanding of the longstream distribution of hydraulic processes is important for evaluating the mechanisms which control the catchment-scale variation of channel stability, sediment transport and siltation, flood generation and aquatic habitats. However, little attention has been given to quantifying the detailed spatial and temporal variability of channel hydraulic parameters, despite considerable attention to reach-scale processes. This study uses a combined field and modelling approach to define the distributions of channel hydraulic parameters between the source and the near-tidal limit of the River Severn, UK. Field measurements were made at 25 logarithmically-spaced sites along the Severn, under 3 flow conditions (low, medium and high) defined by exceedence frequencies. A flow event, occurring between 15-24 February 1989, was simulated by the 1-D hydraulic model, MIKE11. The simulated reach consists of cross sections spaced at 1 km intervals between 4 km and 254 km downstream from the source. Channel hydraulic parameters showed considerable variability in both space and time, reflecting cross section geometry variation downstream. Mean velocity increased with distance downstream from 0.23 m s\(^{-1}\) to 1.72 m s\(^{-1}\) under steady, bankfull flow conditions. However, unsteady flows simulated by MIKE11 demonstrated a longitudinal decline in the mean velocity of the wave peak associated with the rapid movement and minimal attenuation of the flood wave through the unconfined upper Severn. Flow resistance (Manning's n and Darcy-Weisbach f) decreased downstream from the source (0.32 - 0.06), although under low flow conditions it increased from 0.3 to 1.1 downstream to the non-alluvial - alluvial transition at Llanidloes; thereafter it exhibited a steady downstream decline. Reach mean shear stress and unit stream power peaked near the source (5-10 km downstream; drainage area < 50 km\(^2\)) at 120 N m\(^{-2}\) and 290 W m-2 and further downstream at the Ironbridge Gorge (170 km) (38 N m\(^{-2}\); 40 W m\(^{-2}\)) in response to the lithological controls on channel slope and valley width.

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Iyer, Gopalkrishnan R. « The role pf contracts, informal agreements and coalitions in assuring downstream coordination / ». This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-172149/.

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Grove, James Robin. « Downstream change in the processes of riverbank erosion along the River Swale, UK ». Thesis, University of Birmingham, 2001. http://etheses.bham.ac.uk//id/eprint/4429/.

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This study was designed to test the hypothesis that riverbank erosion processes altered with increasing distance from a river source. The River Swale, northern England, was monitored at nine sites throughout its 109-km length, from December 1995 – March 1998. Erosion pins, bank-edge surveying, and Photo-Electronic Erosion Pins (PEEPs) were used to determine rates and timings of erosion. The rates were compared against a range of environmental variables based on temperature, river stage, and precipitation at 14-day intervals for erosion pins and 15-minute intervals for PEEPs. This allowed processes of erosion to be inferred. Catchment erosion rates were modelled using quadratic equations, simulating a mid-basin peak of 3.58 m a\(^{-1}\). Rates of erosion were low upstream, 0.07 m a\(^{-1}\), and also downstream, 0.12 m a\(^{-1}\). Subaerial processes, especially frost action, dominated upstream. Fluvial entrainment was most influential mid-catchment. Mass failures were most efficient downstream, but were more frequent mid-catchment. Piping, sapping and cantilever failures did not follow the same trends and were modelled separately. The length of the erosion season increased downstream as the number of active processes increased.

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Deshmukh, Chandrashekhar. « Greenhouse gas emissions (CH4, CO2 and N2O) from a newly flooded hydroelectric reservoir in subtropical South Asia : The case of Nam Theun 2 Reservoir, Lao PDR ». Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00862380.

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L'augmentation de l'intérêt concernant la part des réservoirs hydroélectrique dans l'augmentation de la concentration atmosphérique des Gaz à Effet de Serre (GES) a amené à mesurer les émissions nettes d'un réservoir hydroélectrique, Nam Theun 2 (NT2) dans la région subtropicale de la République Démocratique Populaire du Laos, Asie. Ce travail est la première évaluation de l'empreinte carbone des GES (c'est à dire : les émissions après ennoiement moins les émissions avant ennoiement) en relation avec la création d'un réservoir hydroélectrique. C'est le résultat d'une étude à grande échelle qui s'est déroulée pendant cinq ans (2008-2012). Nous avons tout d'abord quantifié les sources et les puits majeurs des GES des composants terrestres et aquatiques du paysage avant ennoiement (Mai 2008). Ensuite, à partir d'Avril 2009, cette étude similaire a été réalisée au niveau du réservoir, sa zone de marnage et son aval. C'est en Octobre 2009 que le réservoir hydroélectrique NT2 a, pour la première fois, atteint son niveau maximal et c'est huit mois plus tard, en Mars 2010, que les turbines ont fonctionnées pour la première fois. En se basant sur un suivi bimensuel et sur cinq missions de terrain couvrant toutes les saisons, les émissions des principaux GES (c'est à dire l'oxyde nitreux (N2O), le méthane (CH4) et le dioxyde de carbone (CO2)) ont été mesurées d'Avril 2009 à Décembre 2011. Les émissions ont été déterminées à la surface du réservoir (flux diffusifs et ébullitifs) ainsi que dans les sols de la zone de marnage, qui peut atteindre 370 km2 pour une surface totale de réservoir de 450 km2.

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Iyer, Gopalkrishnan R. « The role of contracts, informal agreements and coalitions in assuring downstream coordination ». Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38523.

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The importance of coordination between independent organizations in a vertical distribution system is stressed in most discussions of marketing channels and inter-organizational relations. The nature and structure of the vertical relation affording effective coordination between autonomous firms or units has been a matter of research interest as well as managerial concern. This thesis attempts to develop and empirically validate a model for understanding the institutional mechanisms for coordination between firms vertically related to each other. An emerging notion in organizational theory and economics is that the firm is a nexus of contracts and economic activities of the firm are governed by contracts ranging from the simple price-quantity contract to more complex adaptive as well as employment contracts. While most or all inter firm relations would be governed by a basic contract, the institutional framework under which any relation would be organized would vary with respect to the use of detailed, sequential contracts; pledges, guarantees and other informal or implicit agreements; and, power, dependency and centralized decision-making. The three institutional mechanisms, contracts, informal agreements, and coalitions differ with respect to their use of bonding mechanisms, power, conflict resolution, and enforcement of obligations. This research attributes the relative predominance of any one institutional mechanism in the vertical relation to relevant industry/market characteristics and firm/transaction considerations within a model unifying theories and concepts from diverse disciplines. Empirical validation of the conceptual model is through a field survey (mail questionnaire) of respondents (mainly top and middle management personnel) drawn from some representative industries. The structural form of the interrelationships between the hypothesized constructs are examined through simultaneous equations modeling and the three-stage least squares estimation procedures. The institutional environment is thus more realistically presented as arising from a combination of environmental and rational selection factors. Moreover, the economic, strategic, relational and transactional properties of inter-organizational relations are considered in one integrated framework. It is hoped that the findings of the study would lead to future theoretical insights that consider the economics, sociology and politics of organizations in a more integrative and realistic framework.
Ph. D.

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Price, Regan R. « Clic Modulates Filopodia Formation Downstream of Cdc42 and its Effectors in Drosophila Hemocytes ». Ohio University Honors Tutorial College / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1338571019.

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OCK, Giyoung. « PARTICULATE ORGANIC MATTER DYNAMICS IN THE DOWNSTREAM OF DAM RESERVOIRS : ROLES OF CHANNEL GEOMORPHOLOGY AND RESPONSES OF BENTHOS COMMUNITIES ». 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120804.

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Ayadi, Abdessalem. « Vers une organisation globale durable de l’approvisionnement des ménages : bilans économiques et environnementaux de différentes chaînes de distribution classiques et émergentes depuis l’entrepôt du fournisseur jusqu’au domicile du ménage ». Thesis, Lyon 2, 2014. http://www.theses.fr/2014LYO22010/document.

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La logistique urbaine, et celle du dernier kilomètre notamment, est un sujet de préoccupation majeure pour les villes d’aujourd’hui. Pour répondre à cette préoccupation, nous avons établi dans le chapitre introductif un historique de la problématique de la logistique urbaine pour mieux comprendre son développement au fil des années, permettant ainsi de déduire qu’il est fondamental d’étudier la globalité de la chaîne de distribution dans ce travail de thèse pour mieux résoudre la problématique de la logistique urbaine. En revanche, nous étions confrontés à un sujet redoutable par sa complexité et l’absence de données complètes et fiables. De plus, nous assistons dans les dernières années, à une multiplication des schémas logistiques que ce soit pour la livraison des magasins à partir des entrepôts des fournisseurs ou pour l’approvisionnement des clients à partir des surfaces de vente.De ce fait, nous avons fixé comme objectif d’identifier toutes les organisations logistiques existantes et émergentes en France et ailleurs (deux séjours d’un an en Angleterre et en Suisse). Pour ce faire, nous avons déterminé dans le deuxième chapitre les paramètres de différenciation des modes d’organisation en amont (de l’entrepôt du fournisseur à la surface de vente) et en aval de la chaîne (de la surface de vente au domicile du client). Or il n’existe pas aujourd’hui de bilan économique et environnemental complet permettant d’arbitrer entre différentes formes de distribution classiques et à distance en tenant compte des particularités des familles des produits (non alimentaires, secs, frais, surgelés) et de la diversité de leurs modes de livraison.Face à ces contraintes de taille, nous avons eu recours aux enquêtes de terrain dans ce travail de recherche, qui ont été l’occasion de nouer de très nombreux contacts avec les acteurs de la grande distribution, permettant ainsi de recueillir des données techniques et économiques de première main et inédites jusqu’ici. En plus de la résolution du verrou empirique dans le troisième chapitre, ce travail de thèse a permis également de lever des verrous méthodologiques relatifs à la reconstitution et à l’évaluation des coûts et des émissions logistiques (pour les entrepôts de stockage et les plateformes de transit en amont ; et pour les surfaces de vente et les plateforme de mutualisation en aval) et des coûts et des émissions des véhicules de transport (des articulés et des porteurs en amont ; et des VUL, voitures particulières, transports publics, deux roues, et marche à pied en aval). Enfin, ce travail de thèse a permis d’aboutir à la construction d’une base de données et la mise au point d’un outil d’aide à la décision permettant ainsi de déduire, dans le quatrième chapitre, les bilans économique et environnemental de la globalité de la chaîne depuis l’entrepôt du fournisseur jusqu’au domicile du ménage. Cet outil devrait se révéler très utile pour les politiques publiques, les stratégies futures des grands distributeurs et leurs prestataires logistiques afin de privilégier les modes d’organisation économes et durables, et même pour le client final afin d’estimer les coûts et les émissions de ses actes d’achat dans les différentes alternatives de vente classique et à distance
Urban logistics and the last mile in particular, is a major concern for cities today. To address this concern, we have established in the introductory chapter a history of the problem of urban logistics. This allows a better understanding of its development over the years, and deducing that it’s essential to study the supply chain in its entirety to better solve the problem of urban logistics. However, we were faced with a daunting task: the lack of comprehensive and reliable data. In addition, there has been a multiplication of distribution channels in recent years. This includes the delivery from warehouses to stores and further to households from the retail space.Therefore, we intended to identify all existing and emerging logistics organizations in France and beyond (one year exchange stay in England and Switzerland for research purposes). To do this, we established in the second chapter certain parameters that differentiate the logistics modes of various organizations upstream (from manufacturers to retail stores) and downstream (from retail stores to households). Unfortunately, there does not exist any economic and environmental assessment to settle between different forms of traditional and modern electronic distribution, by taking into account the various characteristics of different products families (non-food, dry, fresh, frozen) and the diversity of their delivery modes.Faced with constraints of such size, we conducted surveys with different actors of distribution channels, which provided the opportunity to make contacts, thus collect firsthand and so far unpublished technical and economic data. In addition to the resolution of empirical inadequacy in the third chapter, this research also helped to develop a methodological approach related to the reconstruction and evaluation of logistics costs and emissions (in warehouses, transit platforms, retail stores and shared platforms) and also the costs and emissions of vehicles (trucks, delivery van, cars, public transport, bikes, motorbikes and walking).Finally, this research has lead to the construction of a database and the development of a decision support tool to infer, in the fourth chapter, the economic and environmental appraisal of the entire supply chain from the supplier's warehouse to the final customer. This tool can be useful for public policy, future strategies of retailers and Third-Party Logistics providers to focus on efficient and sustainable modes of organization, and even it will benefit the customer to estimate the costs and emissions of its acts of purchase in classic and e-grocery shopping

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Chung-EnHung et 洪崇恩. « Downstream Morphologic Changes Due To Reservoir Desilting ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/89232677208761970228.

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碩士
國立成功大學
水利及海洋工程學系
103
Part of the Circum-Pacific Seismic Zone, Taiwan has been frequently struck by earthquakes that lead to soft soil. As extreme rainfall caused by climate change is increasing, a large volume of sediment from upstream flows into reservoirs in every rainy season followed by severe deposition which affects the useful life of reservoirs. To keep reservoirs sustainable, methods are carried out in many reservoirs for desilting. After desilting, a large volume of sediment flows from reservoirs to downstream that changes the downstream morphology and influences ecological safety and flood control. Taking the downstream of Agongdian Reservoir and Nanhua Reservoir as the studied area, the study through field survey and data collection (section topography and particle size analysis) evaluates the effect of desilting on the downstream morphology. According to the scouring and silting variation, it is known that, upon desilting, the bulk of sediment released from Agongdian River can be transported to the downstream at 4,436 m from the reservoir effluent. Nanhua Reservoir simulation and two topographic data demonstrate a great sediment transport in the downstream way. With simulation of sediment releasing, only a small volume of sediment in the downstream river occurs as a complement to a shortage of sediment in the downstream after reservoir is built. It is known from an analysis of the fine sediment infiltration that, without desilting tunnel, the watercourse itself with great carrying capacity improves the fine sediment infiltration. Building reservoir causes long shortage of sediment and channel erosion in the downstream river, so sediment released from reservoir is a complement to the downstream morphology. Generally, reservoir desilting has beneficial effect on the downstream morphology, in terms of sediment.

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Yeoh, Jiann Wei. « Drug-induced changes to lateral hypothalamic circuits and downstream projection targets ». Thesis, 2015. http://hdl.handle.net/1959.13/1309854.

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Research Doctorate - Doctor of Philosophy (PhD)
The lateral hypothalamus (LH) contains a large number of neuropeptide transmitter-expressing neurons that act to co-ordinate consummatory and reward-seeking behaviours. My thesis focuses on two classes of these neuropeptides; orexins, of which I generally classified as ‘pro’ reward-seeking and cocaine and amphetamine reward transcript (CART) peptides, commonly considered to be ‘anti’ reward-seeking. For example, in the context of drug addiction, activation of the orexin system generally promotes the reinstatement of cocaine-seeking behaviour, whereas the majority of the studies have demonstrated that increased CART signalling negatively regulates drug-motivated behaviours. Critically, it remains unclear how these systems interact and modulate the output of key nodes of the reward seeking circuitry. Therefore, in this thesis I address a number of outstanding questions regarding how changes in the activity of orexin or CART neurons might behavioural output controlled by the reward-seeking circuit. First, using ex vivo slice electrophysiology, I assessed how orexin circuitry in the LH is modified by cocaine exposure in rats that were passively exposed to cocaine or were trained to self-administer cocaine in operant boxes. Immunohistochemical detection of markers of glutamatergic versus GABAergic synapses was used to estimate and identify changes in presynaptic inputs onto orexin neurons after cocaine. I found evidence of increased presynaptic drive and excitatory terminals onto orexin neurons irrespective of whether animals self-administered or injected passively with cocaine. In Chapter 2, I determined if similar changes occur in orexin neurons from transgenic mice where the reporter gene (green fluorescent protein, GFP) was driven by the orexin promoter. These studies are important in order to take advantage of the expanding transgenic approaches in mice in the future. Further, I also tested the longevity of presynaptic drive to orexin neurons produced by cocaine and examined whether activation of group III metabotropic glutamate receptors could reverse any of the changes induced by cocaine. These studies showed that presynaptic drive to LH orexin neurons persists for at least two weeks after animals were withdrawn from cocaine. Further, activation of GP-III mGluRs curtailed the cocaine-induced increase in glutamate release onto orexin neurons. Previous work in our lab has identified that CART peptide injections but not orexin receptor antagonism in the PVT negatively regulates drug seeking behaviour. Therefore I assessed in Chapter 3 how cocaine influences the normal firing properties of PVT neurons and whether, as predicted by our previous behavioural studies, CART reduces PVT neuron activity. In the final chapter of my thesis, I summarise and integrate my results in the context of the wider literature and attempt to present a synthesis of LH based changes with relevance to addiction and other psychiatric conditions such as depression and anxiety.

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Sackett, Judy, et Maureen Sullivan. « Downstream from Team : Riding the Rapids of Reorganization ». 2006. http://hdl.handle.net/10150/222275.

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Conference proceeding from the Living the Future 6 Conference, April 5-8, 2006, University of Arizona Libraries, Tucson, AZ.
From the mid-1990s through 2004, the University of Kentucky Libraries were organized in a team-based organizational structure. The team structure was implemented in concert with the opening of the new main library, and its focus was on service centers that featured rotating leadership and management by consensus. Over the course of six or seven years, the model thrived in some units and created difficulty in others. Find out about the process of reorganizing a library from a team-based structure, and discover how a small working group developed a new organization focusing on users, work redesign, and accountability. Learn the basic steps in a system-wide work redesign process and complete a brief assessment of your library's readiness for work redesign.

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Chiu, Shiao-Yen, et 邱曉燕. « The Formation and Changes of Local Society at the Downstream of Xihu River ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85646252056871286386.

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碩士
國立交通大學
客家文化學院客家社會與文化學程
101
This research is based on the phenomenon of the concentrated temples and the overlapped religious sphere around the Dianzai Street in Xihu County, Miaoli. By discussing the symbols of religion and the interactions of powers, the study observes the cultural aspects and connections of the local society. Constructed from bottom to top, the symbolic stratum of the local religion is used to explain the progress and development of the four outer villages in Xihu County. On the other hand, the once regionalized Xihu County which resulted from the union of the frontier guard posts evolved into “Four Outer Villages” and “Three Inner Villages”, which have two separate systems of Mazu pilgrimages that clarify the relation between the two local societies of the Xihu River Basin. This study discovers that based on the Central Place Theory, Dianzai Street is the central location due to the geological and transporting factors. The concentrated temples of the Four Outer Villages represent the struggles of powers. The diversity of the local lineages forms a superior religious stratum including the Liu family’s ancestral shrine. The Four Outer Villages and the local lineages maintain a balance based on the religious stratum. The Four Outer Villages and the Three Inner Villages share the historic memory of the union of the frontier guard posts and therefore construct two religious symbol systems to distribute water resource. The competition for power and the interaction of different cultural factors form the overlapped religious symbol systems and develop its locality and unique culture of local society.

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Hsu, Yung-Ching, et 許詠晴. « The Effects of Slit Dam Removal Processes upon Upstream and Downstream Channel Bed Form Changes Experiments ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/w8xc39.

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CHIANG, PEI-YU, et 江珮鈺. « The Impact of Land Use Changes on the Mid-Downstream of River Pollution Index in Fengshan River Basin ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/927vv6.

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碩士
國立臺中教育大學
科學教育與應用學系環境教育及管理碩士班
107
In response to the needs of human life, land use patterns are constantly changing, and while changing land use, it will also change the geography, hydrology, and ecology in the environment. In order to understand whether the change of land use pattern has any impact on river pollution, this study uses the SPOT satellite images of the Fengshan River Basin in Hsinchu County in 2003, 2013 and 2017 to use the most approximate method of supervised classification for land use type. To classify and analyze the changes in important water quality parameters of the Fengshan River Basin in Hsinchu County, and to explore the following research purposes: First, understand the changes in different land use patterns in the Fengshan River Basin. Second, understand the changes on the river pollution index and important water quality parameters in Fengshan River Basin. Third, explore the relationship between land use change and river pollution index in Fengshan River Basin. The results show that the land use pattern in the Fengshan River Basin increased from 2003 to 2017, while the river basin and the important water quality parameters showed a decrease, namely the forest area. It is negatively correlated with the river pollution index.

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韓孟學. « Experimental Study on Influence of Different Inflow Angles on Flow Field and Bed Changes Upstream and Downstream of Weir ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3w98h6.

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碩士
國立交通大學
土木工程系所
106
Due to Taiwan’s rivers being steep with rapid flood flow, dams and weirs are usually built for the purpose of water resources supply and river stabilization. There are many types of damage to the dams or weirs, and the damage on the spillway surface is the most common type. The damage comes from the collision of coarse sediments on the spillway surface, which will erode the internal structure and finally endanger the safety of the weir/dam. When the weir is built on a meandering river, the incoming flow will be not perpendicular to the weir axis and thus result in additional vortex flow. This vortex flow will pull up the bed material before the weir and the collision will occur during the passage of the flow. There are few in the literature on this topic. Therefore, this study focuses on the inflows not perpendicular to the weir axis, and uses the PIV to measure the horizontal flow fields at different vertical levels, under fixed- and movable-bed conditons. This study result reveals that upstream flow field can be divided into two parts: one flows fast to the downstream, the other becomes recirculation before the dam due to the large difference in the flow velocities. In recirculation region, size of vortex grows with water depth and flow discharge. Intensity of vortex depends on the inflow angel and velocity. Being in a cycle series, vortex grows from small to strong and then disappears due to energy disspipation with duration time between 1 to 1.8 seconds. The range of inflow angel narrows down with rising the flow rate.Upstream bed deforms amd grows as a dune and thus makes vortex concentrated and strong. Due to inclined inflow, the flow shifts forward the bank of the flume after passing the weir. The downstream scour hole shifts away from the centerline and the alternative bars occur.

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Kuan-HsienLan et 藍冠顯. « To investigate the downstream signaling change induced by the IL-6 glycoforms ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/bq43n2.

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Thayer, James Benjamin. « Downstream Variability of Fluvial Form, Process, and Character in a Small Deglaciated Watershed, Southern Ontario ». Thesis, 2012. http://hdl.handle.net/1807/33568.

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Many deglaciated watersheds possess complex longitudinal profiles and spatially variable sediment sources derived from the last glaciation. Accordingly, downstream patterns in fluvial forms and characteristics of the channel and floodplain may diverge from conventional ‘graded’ watershed models where channel slope decreases downstream. Within a small, deglaciated watershed, five distinct fluvial forms were identified and it was found that the watershed is organized in a spatially variable, but generally inverted arrangement with stable, low-energy forms dominating the upper watershed and more dynamic, high-energy forms in the lower watershed. As a consequence of this inverted and variable downstream succession, and the spatially erratic organization of glacial sediment sources, downstream trends in channel and floodplain characteristics are poorly defined, and in many cases, deviate from expected trends. This is most true for sedimentological variables where multiple co-dominant controls exist, while morphological and hydrological variables better conform to expected downstream trends.

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Olah, Michelle Elizabeth. « The Activation of Novel Calcium-dependent Pathways Downstream of N-methyl-D-aspartate Receptors ». Thesis, 2009. http://hdl.handle.net/1807/24324.

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Calcium (Ca2+) influx through N-methyl-D-asparate receptors (NMDARs) is widely held to be the requisite step initiating delayed neuronal death following ischemic stroke. However, blocking NMDARs fails to prevent the accumulation of intracellular Ca2+ ([Ca2+]i) and subsequent neurotoxicity. This suggests that alternate, as yet uncharacterized Ca2+-influx pathways exist in neurons. Transient receptor melastatin 2 (TRPM2) is a Ca2+-permeable member of the transient receptor potential melastatin family of cation channels whose activation by reactive oxygen/nitrogen species (ROS/RNS) and ADP-ribose (ADPR) is linked to cell death. While these channels are broadly expressed in the central nervous system (CNS), the presence of TRPM2 in neurons remains controversial and more specifically, whether they are expressed in neurons of the hippocampus is an open question. Here, I employ a combination of molecular, biochemical and electrophysiological approaches to demonstrate that functional TRPM2 channels are expressed in pyramidal neurons of the hippocampus. Unlike in heterologous expression systems, the ADPR-dependent activation of TRPM2 in neurons required a concomitant rise in [Ca2+]i via either voltage-dependent Ca2+ channels or NMDARs. While short, repeated NMDA applications activated a TRPM2-like current in the absence of exogenous ADPR, sustained NMDA application to hippocampal neurons resulted in the activation of a pannexin1 (Px1) hemichannel. Px1 hemichannels are large conductance, nonjunctional gap junction channels that can be activated following periods of oxygen-glucose deprivation (OGD) in neurons. Activation of Px1 required the influx of Ca2+ through NMDARs. Supplementing the intracellular milieu with adenosine triphosphate (ATP) prevented Px1 activation, suggesting that hemichannels may be activated during periods of mitochondrial dysfunction and metabolic failure. Our findings have potential implications for the treatment of diseases such as cerebral ischemia and Alzheimer’s disease (AD) as they implicate two novel ion channels in the excitotoxic signaling cascade activated downstream of NMDARs.

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Mao, De Yu. « Chloride Intracellular Channel (CLIC) proteins function to modulate Rac1 and RhoA downstream of endothelial G-protein coupled receptors signaling ». Thesis, 2019. https://doi.org/10.7916/d8-eyrq-5w43.

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Chloride intracellular channel proteins have homology to ion channels and omega class of glutathione-S-transferases but channel activity is not well established, suggesting roles in other signaling pathways. Among the six CLICs, CLIC1 and CLIC4 are expressed in endothelial cells (EC) and act to promote EC proliferation, capillary-like networks, and lumen formation. We and others determined that Sphingosine-1-phosphate (S1P) signaling promotes transient CLIC4 membrane localization. We report that CLIC1 and CLIC4 have distinct roles in endothelial S1P signaling. In knockdown studies, CLIC1 and CLIC4 were independently required for S1PR1-mediated Rac1 activation, enhanced EC barrier integrity, and EC migration. CLIC1 was uniquely required for S1PR2/3-driven RhoA activation and actin stress fiber formation, while CLIC4 was uniquely required for thrombin/PAR-driven RhoA activation and endothelial permeability. CLICs were not required for other GPCR-mediated pathways measured, including S1PR1-mediated cAMP regulation downstream of Gαi, or Ras and ERK activation downstream of Gβγ. Endothelial β-adrenergic signaling, which uses Gαs, was unaltered by loss of CLICs. Further investigation of receptor tyrosine kinase signaling (VEGF, EGF) in endothelial cells reveals their signaling cascades do not depend on CLICs as well. We conclude that CLICs mediate S1PR-driven RhoA and Rac1 regulation, and thrombin/PAR-driven RhoA activation, and a possible mediator for endothelial GPCR by modulating Rac1 and RhoA. CLIC N-termini contain membrane insertion motifs and the putative ion channel domain, while the C-termini contain two predicted SH domains. Chimeric proteins generated by swapping N and C-termini of CLIC1 and CLIC4 were used in rescue experiments. The C-terminal domain was determined to confer S1PR1-CLIC-Rac1 mediated barrier function and migration. We further characterized N-termini of CLIC4 and membrane localization of by generating CLIC4 C-termini truncated protein, along with CLIC4 C-termini fusing with Lck-peptide for myristylation and plasma membrane re-localization. CLIC4 C-termini alone fails to rescue S1PR1-CLIC-Rac1 mediated barrier function, while membrane localization of the CLIC4 C-terminal domain functions in S1P signaling, suggesting the N-terminal domain confers membrane localization but not signaling function. Thus, we conclude S1P promotes cell localization of CLIC4 to the EC plasma membrane through N-termini, which then regulates Rac1 mediated events through C-termini. Through these findings, our work defines a molecular mechanism through which CLICs function in endothelium.

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Taha, T., A. O. A. Lateef et Jaan H. Pu. « Laminar and turbulent analytical dam break wave modelling on dry-downstream open channel flow ». 2018. http://hdl.handle.net/10454/16598.

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Yes
A dam break wave caused by the discontinuity in depth and velocity of a flow is resulted from instantaneous release a body of water from a channel and classified naturally as a rapidly varied unsteady flow. Due to its nature, it is hard to be accurately represented by analytical models. The aim of this study is to establish the modelling differences and complexity echelons between analytically simulated explicit laminar and turbulent dry bed dam break wave free surface profiles. An in-depth solution to the free surface profile has been provided and evaluated by representing the reported dam break flow measurements at various locations. The methodology adopted utilizes the free surface profile formulations presented by Chanson 1,2, which are developed using the method of characteristics. In order to validate the results of the presented analytical models in illustrating the dam break wave under dry bed conditions, published experimental data provided by Schoklitsch 3, Debiane 4 and Dressler 5 are used to compare and analyze the performance of the dam break waves under laminar and turbulent flow conditions.

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CHEN, ALEX, et 陳宥叡. « A Study on Change of Upstream and Downstream River Bed of Flood Detention Dam been Reconstructed from the Check Dam ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/36415212735306666183.

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碩士
國立中興大學
水土保持學系
87
In Taiwan, check dam is one of the major structural measures for upstream channel improvement. However, the original river bio-system, especially, on the fish habitat, is seriously affected when the step-form stream channel is created after check dams were filled. With higher attention on natural environment protection, searching for alternatives of Check Dam becomes one of important research topics in this field and re-constructing traditional check dam into Detention Dam is one of the feasible techniques. Check Dam no.3 and no.4 of Gaul-Shane Creek were chosen for this experiment study under hydrology condition of 50 years of return period. With different final dam configurations for these two dams, the model experiments tried to conclude some principles regarding to the deposit slopes of dams, changes in cross sections, dimension of scouring hole, and sediment discharge of observed channel. From the result of this experiment, the average deposit slope, changes in cross sections, scouring hole, and sediment discharge of downstream channel of dam No.4 increased with deeper opening depth of dam No.3. Therefore, the protection of Dam No.4 should be completed to reduce potential damage before re-construction of dam No.3 being proceeded. Besides, the effects on those channel morphologic phenomena were milder when the opening-developing procedures were applied gradually.

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Heitmuller, Franklin Thomas. « Downstream trends of alluvial sediment composition and channel adjustment in the Llano River watershed, Central Texas, USA : the roles of a highly variable flow regime and a complex lithology ». 2009. http://hdl.handle.net/2152/6900.

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This study investigates the downstream controls of alluvial sediment composition and river channel adjustment in the Llano River watershed, Central Texas, USA. The Llano River watershed is characterized by a highly variable, flood-prone flow regime and a complex lithology of Cretaceous carbonate rock, Paleozoic sedimentary rock, and Precambrian igneous and metamorphic rock. Sedimentary variables for this study include particle size, sorting, carbonate content, and magnetic susceptibility. Channel adjustment includes the planform dimension and cross-sectional dimensions of bankfull- and macro-channels. Nineteen sites along the Llano River and selected tributaries were visited to measure cross-sectional channel geometry and sample bed, bank, and overbank sediment. Laboratory analyses of sediment and hydraulic analyses of cross sections were accompanied by analyses of partial-duration flood frequency, flow resistance, hydrography, digital elevation models, and statistical correlation. Findings include: (1) channel-bed material reduces in size with downstream distance, despite increasing valley confinement and bedrock exposure; (2) the downstream decrease in particle size is more evident for channel-bar deposits than for low-flow-channel (thalweg) deposits; (3) an abrupt gravel-to-sand transition occurs about 20 kilometers downstream of the Paleozoic-Precambrian contact; (4) an abrupt coarse- to fine-gravel transition occurs between 75 and 90 kilometers downstream the North Llano and South Llano Rivers; (5) channel-bank material increases downstream, contrasting with decreases in bed material; (6) carbonate content and magnetic susceptibility of alluvial sediment are inversely related, with carbonate content peaking near Junction; (7) four general categories to classify reaches of the North Llano, South Llano, and Llano Rivers are based on hydrology, planform morphology, lithology, and valley confinement; (8) mean depth increasingly compensates for bankfull discharge in a downstream direction; (9) mean depth compensates more than width for macrochannels; and (10) the return periods for bankfull and macro-channels are about 1 to 2 years and greater than 10 years, respectively. The results of this study will contribute to fluvial geomorphic theory of downstream trends in sediment composition and channel adjustment; as well as inform applied efforts related to aquatic biology, flood hazards, infrastructure design, and riparian and water-resource management in the region.
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