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Goz, Caglayan. "Instream Flow Methodologies: Hydrological Environmental Flow Assessment In Pazarsuyu River." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615004/index.pdf.
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In Turkey with increasing energy demand by industrialization and urbanization, hydropower seemed to be the most environmental friendly and sustainable solution for
the problem. However, hydropower has also environmental effects especially when hydropower projects are numerous on a single river, and they use almost entire water in
the river. Environmental flow as a new term became popular in media with increased density of small hydropower projects in Turkey. It is the required flow in the part of diversion for Run-off River type of hydropower plant in order to protect health of the riverin other words, to balance components of the river, including physico-chemical quality standards, surface and groundwater, geomorphological dynamics, social, economic, cultural and landscape values. In this study, an analysis utilizing hydrological (desktop) environmental flow assessment methods is prepared for Turkey, focusing on the Pazarsuyu Basin as a case study, and the results are compared with the applications done by the Governmental Institutions. Moreover, insufficient applications with regard to environmental flow assessment are given and reasons for public concerns are pointed out due to small hydropower development in Turkey.
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Petersson, Sven. "Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-100146.
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The study of blood flow is essential in understanding the physiology and pathophysiology of the cardiovascular system. Small disturbances of the blood flow may over time evolve and contribute to cardiovascular pathology. While the blood flow in a healthy human appears to be predominately laminar, turbulent or transitional blood flow is thought to be involved in the pathogenesis of several cardiovascular diseases. Wall shear stress is the frictional force of blood on the vessel wall and has been linked to the pathogenesis of atherosclerosis and aneurysms. Despite the importance of hemodynamic factors, cardiovascular diagnostics largely relies on the indirect estimation of function based on morphological data. Time-resolved three-dimensional (3D) phase-contrast magnetic resonance imaging (MRI), often referred to as 4D flow MRI, is a versatile and non-invasive tool for cardiovascular blood flow assessment. The use of 4D flow MRI permits estimation of flow volumes, pressure losses, wall shear stress, turbulence intensity and many other unique hemodynamic parameters. However, 4D flow MRI suffers from long scan times, sometimes over 40 minutes. Furthermore, the accuracy of the many different 4D flow MRI-based applications and estimates have not been thoroughly examined. In this thesis, the accuracy of 4D flow MRI-based turbulence intensity mapping and wall shear stress estimation was investigated by using numerical simulations of MRI flow measurements. While the results from the turbulence intensity mapping agreed well with reference values from computational fluid dynamics data, the accuracy of the MRI-based wall shear stress estimates was found to be very sensitive to different parameters, especially to spatial resolution, and wall shear stress values over 5 N/m2 were not well resolved. To reduce the scan time, a 4D flow MRI sequence using spiral k-space trajectories was implemented and validated in-vivo and in-vitro. The scan time of 4D flow MRI was reduced by more than two-fold compared to a conventional Cartesian acquisition already accelerated using SENSE factor 2, and the data quality was maintained. For a 4D flow scan of the human heart, the use of spiral k-space trajectories resulted in a scan time of around 13 min, compared to 30 min for the Cartesian acquisition. By combining parallel imaging and spiral trajectories, the total scan time of a 4D flow measurement of the entire heart may be further reduced. This scan time reduction may also be traded for higher spatial resolution. Numerical simulation of 4D flow MRI may act as an important tool for future optimization and validation of the spiral 4D flow sequence. The scan-time reductions offered by the spiral k-space trajectories can help to cut costs, save time, reduce discomfort for the patient as well as to decrease the risk for motion artifacts. These benefits may facilitate an expanded clinical and investigative use of 4D flow MRI, including larger patient research studies.
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Stanger, Jonathan Jeffrey. "Experimental Assessment of Charge Flow in Electrospinning." Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8447.
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Electrospinning is a method of using high voltage electric fields to transform polymer solutions into nano-scale fibres. The field has seen significant work on processing different polymers and their resulting fibres but less work has focused the electrospinning process itself. The aim of this thesis is to present experimental observations of charge behaviour in the electrospinning process in the context of the underlying physics typically used to describe electrospinning. This thesis presents a review of existing methods of measuring aspects of the electrospinning process, and reviews published mathematical models of the process as representative examples of the current understanding of the underlying physics that drive the electrospinning phenomena. A novel measurement technique is introduced - high frequency data capture of the electric current flow simultaneously at the high voltage and collector electrode. This is used in three ways: to examine bulk charge density, to measure fibre flight time, and to quantify charge lost from the fibre in flight. Charge density is studied by comparing current and mass flow at the Taylor cone under a wide range of conditions. For 8% PVOH in water a constant bulk charge density was found of 7.7 C/kg. Flight time is studied by determining the time from the application of high voltage to the charged fibre first arriving at the collector electrode. It was found that for 8% PVOH the flight time depended strongly on applied voltage while electrode distance had a negligible effect. Charge loss was studied by comparing the magnitude of the simultaneous current flows in the quasi-steady state to determine if the charge flowing into the Taylor cone arrives with the fibre at the collector. For 8% PVOH, 8% PVOH with ionic salt, 9% PVOH in water and 18% PVB in ethanol, it was found that charge is always lost.
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Grigorescu, Fredriksson Alexandru. "Blood flow specific assessment of ventricular function : Visualization and quantification using 4D flow CMR." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143417.
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The spectrum of cardiovascular diseases is the leading cause of morbidity and mortality globally. Early assessment and treatment of these conditions, acquired as well as congenital, is therefore of paramount importance. The human heart has a great ability to adapt to various hemodynamic conditions by cardiac remodeling. Pathologic cardiac remodeling can occur as a result of cardiovascular disease in an effort to maintain satisfactory cardiac function. With time, cardiac function diminishes leading to disease progression and subsequent heart failure, the end-point of many heart diseases, associated with very poor prognosis. Within the normal cardiac ventricles blood flows in highly organized patterns, and changes in cardiac configuration or function will affect these flow patterns. Conversely, altered flows and pressures can bring about cardiac remodeling. In congenital heart disease, even after corrective surgery, cardiac anatomy and thereby intracardiac blood flow patterns are inherently altered. The clinically most available imaging technique, ultrasound with Doppler, allows only for one-directional flow assessment and is limited by the need of clear examination windows, thus failing to fully assess the complex three-dimensional blood flow within the beating heart. Cardiovascular magnetic resonance imaging (CMR) with phase-contrast has the ability to acquire three-dimensional (3D), three-directional time resolved velocity data (3D + time = 4D flow data) from which visualization and quantification of blood flow patterns over the complete cardiac cycle can be performed. Four functional blood flow components have previously been defined based on the blood route and distribution through the ventricle, where the inflowing blood that passes directly to the outflow is called Direct flow. From these components, various quantitative measures can be derived, such as component volumes and kinetic energy (KE) throughout the cardiac cycle. In addition, the 4D flow technique has the ability to quantify and visualize turbulent flow with increased velocity fluctuations in the heart and vessels, turbulent kinetic energy (TKE). The technique has been developed and evaluated for assessment of left ventricular (LV) blood flow in healthy subjects and in patients with dilated dysfunctional left ventricles, showing significant changes in blood flow patterns and energetics with disease. There is however still no study addressing the gap in the spectrum from the healthy cohorts to patients with moderate to severe left ventricular remodeling. In Paper III, 4D flow CMR was utilized to assess LV blood flow in patients with subtle LV dysfunction, and a shift in blood flow component volumes and KE was seen from the Direct flow to the non-ejecting blood flow components. In patients with both left- and right-sided acquired and congenital heart disease, right ventricular (RV) function is of great prognostic significance, however this ventricle has historically been somewhat overseen. With its complex geometry, advanced physiology and retrosternal location, assessment of the RV is still challenging and the right ventricular blood flow is still incompletely described. In Paper I, the RV blood flow in healthy subjects was assessed, and the proportionally larger Direct flow component was located in the most basal region of the ventricle and possessed higher levels of KE at end-diastole than the other flow components suggesting that this portion of blood was prepared for efficient systolic ejection. In Paper II, the blood flow was assessed in the RV of patients with subtle primary LV disease, and even if conventional echocardiographic or CMR RV parameters did not show any RV dysfunction, alterations of flow patterns suggestive of RV impairment were found in the patients with the more remodeled LVs. With improvements of the cardiovascular health care, including the surgical techniques, the number of adult patients with surgically corrected complex congenital heart diseases increases, one of which is tetralogy of Fallot (ToF). Surgical repair of ToF involves widening of the pulmonary stenosis, which postoperatively may cause pulmonary insufficiency and regurgitation (PR). Disturbed or turbulent flow patterns are rare in the healthy cardiovascular system. With pathological changes, such as valvular insufficiency, increased amounts of TKE have been demonstrated. Turbulence is known to be harmful to organic tissues and could be significant in the development of ventricular remodeling, such as dilation and other complications seen in Fallot patients. In Paper IV, the RV intraventricular TKE levels were assessed in relation to conventional measures of PR. Results showed that RV TKE was increased in ToF patients with PR compared to healthy controls, and that these 4D flow-specific measures related slightly stronger to indices of RV remodeling than the conventional measures of PR. 4D flow CMR analysis of the intracardiac blood flow has the potential of adding to pathophysiological understanding, and thereby provide useful diagnostic information and contribute to optimization of treatment of heart disease at earlier stages before irreversible and clinically noticeable changes occur. The flow specific measures used in this thesis could be utilized to detect these alterations of intracardiac blood flow and could thus act as potential markers of progressing ventricular dysfunction, pathological remodeling or used for risk stratification in adults with early repair tetralogy of Fallot. Visualizations of intracardiac flow patterns could provide useful information to cardiac/thoracic surgeons pre- and post-operatively.
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Madden, Jacqueline. "Flow cytometric assessment of T cell activation in asthma." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245048.
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Kao, Tsu-Mu 1958. "Incorporating flow-accelerated corrosion effects into probabilistic risk assessment." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9402.
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Cavusoglu, Ozge. "Assessment of managed lanes options." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/cavusoglu.pdf.
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Silvester, Ian Harvey. "The accurate assessment and monitoring of asthma." Thesis, Staffordshire University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262759.
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Lagerblad, Lovisa. "Assessment of environmental flow requirements in Buzi River basin, Mozambique." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-150870.
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Rivers belong to the world’s most complex ecosystems but increasing demands for water are degrading rivers worldwide. The increase in human populations and activities has resulted in an intense and difficult conflict between the development of rivers as a natural resource and their function as living ecosystems. It is now widely recognized that a naturally variable flow regime is required to sustain freshwater ecosystems. Many countries that experience river degradation have started to implement environmental flows, i.e. the unallocated flow purposely preserved in a river. The objectives of this thesis are twofold. The first aim is to briefly describe the concept and science of environmental flows and the different methodologies for calculating environmental flows. This was done based on a literature review of the subject. The second aim is to present a case study calculating the environmental flow requirements. The case study was conducted through a field study in the Buzi River basin in Mozambique and the subsequent modeling of the environmental flow requirements. The literature study showed that not only the quantity of water is important; the timing and frequency of floods, droughts, low flows and high flows are very important as well. The literature study also showed that the advances in environmental flow science have been remarkable while the water policy and management has not been equally successful in implementing environmental flow standards. The calculation of environmental flow requirements was done with the Desktop Reserve Model developed in South Africa. The results indicated that to maintain the ecological status in the Buzi River at a largely natural condition (ecological category A) an average allocation of 57 % of mean annual runoff (MAR) is required. The present ecological status was determined in Revue River, which is one of the three major tributaries to Buzi River. To maintain the Revue River at its present ecological state requires an environmental flow between 23-37 % of MAR. The major environmental threats in Revue River are erosion and flow modification. The erosion is a consequence from artisanal gold mining, inadequate farming practices and deforestation. The flow alterations are caused by the large Chicamba Dam constructed for the generation of hydropower. One of the questions this thesis aimed to answer was if it was possible to set the present ecological state with a limited amount of data. This study showed that it could be possible but that the confidence level will be low. The relationships between ecological metrics and flow alterations must be investigated in detail for this region before environmental flow requirements can be successfully calculated and implemented.Floder hör till jordens mest komplexa och känsliga ekosystem, men ett ökat tryck på våra vattenresurser har försämrat situationen för många av världens floder. Befolkningsökningen och den globala utvecklingen har resulterat i en intensiv och komplicerad konflikt mellan utnyttjandet av floder som en naturresurs och bevarandet av deras funktion som unika ekosystem. Det är nu allmänt accepterat att den naturliga flödesvariabiliteten behövs för att bevara våra sötvattenekosystem. Flera länder där försämringen av floder är ett faktum har börjat införa miljöanpassade flöden, det vill säga vatten som medvetet tilldelas flodens ekosystem. Det finns två syften med det här examensarbetet. Det första är att genom en litteraturstudie beskriva miljöanpassade flöden och de modeller som används för att beräkna detta flöde. Det andra målet är att göra en fallstudie och beräkna det miljöanpassade flödet och bestämma den ekologiska statusen för Buzi floden i Moçambique. Litteraturstudien visade att det inte bara är kvantiteten av vatten som är viktigt; tidpunkt och återkomsten av översvämning, torka, lågflöden och högflöden är mycket viktiga om man vill efterlikna det naturliga flödet. Litteraturstudien visade även att framstegen i kunskapen om miljöanpassade flöden har varit stora medan vattenlagstiftningens anpassning och införandet av miljöanpassade flöden har varit svag i flera avseenden. Modellerandet gjordes med den sydafrikanska Desktop Reserve Model. Resultaten från modellen visade att för att bibehålla den ekologiska statusen för Buzi floden i ett nära naturligt stadium (ekologisk klass A) krävs en tilldelning på 57% av medelårsavrinningen. Den nuvarande ekologiska statusen bestämdes i Revue floden, som är en av tre huvudfloder i Buzi avrinningsområdet. För att behålla Revue floden i sitt nuvarande tillstånd skulle kräva ett miljöanpassat flöde på mellan 23-37% av medelårsavrinningen. De största ekologiska hoten i Revue floden visade studien var erosion och flödesförändringar. Erosionen är en konsekvens av guldutgrävning, jordbruk med fel teknik, och skogsavverkning. Flödesförändringarna härrör från den stora vattenkraftsstationen Chicamba Dam. En av frågorna den här studien syftade till att besvara var om det är möjligt att bestämma den nuvarande ekologiska statusen med en begränsad tillgång till data. Studien visade att det är möjligt men att osäkerhetsnivån i resultatet kommer att vara stort. Studien visade även att modellen Desktop Reserve Model kan användas för snabba beräkningar av det miljöanpassade flödet, men att mer utförliga studier som till exempel Building Block Methodology måste genomföras innan resultatet med säkerhet kan verifieras. Relationen mellan ekologiska förändringar och flödesvariationer måste utredas i detalj för studieområdet innan de miljöanpassade flödesbehoven kan bli implementerade med framgång.
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Márquez, Valle Patricia. "A confidence framework for the assessment of optical flow performance." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/305105.
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L’Optical Flow (OF) és l’input d’una gran varietat de Sistemes de Suport a Decisions
(DSS) com ara assistència a la conducció, guia UAV o diagnosis mèdic. En aquestes
situacions, l’absència de ground truth ens obliga a avaluar la qualitat de l’OF calculat
mitjançant quantitats calculades a partir de les seqüències o bé a partir del mateix
OF. Aquestes quantitats es coneixen generalment com a Mesures de Confiança (CM).
Encara que tinguem una mesura de confiança, necessitem alguna eina per tal d’avaluar
la seva capacitat per descartar píxels de la imatge que tenen tendència a tindre error.
Els mètodes actuals només aporten una avaluació descriptiva del rendiment de les
CM, el problema és que aquests mètodes no són capaços de comparar equitativament
les diferents CM i OF. Així doncs, necessitem definir una metodologia que avalu¨ı el
rendiment de les tècniques d’OF.
Aquesta tesi aporta la definició d’una metodologia que ens permet decidir quines
parelles ”optical flow - mesura de confiança” (OF-CM) estan millor preparades per a
definir una cota de l’error de l’OF donat un nivell de confiança per a un DSS. Per tal
de definir aquesta metodologia, la tesis engloba els següents punts:
• Marcadors qualificatius. Es presenten 3 gràfiques descriptives que avaluen
de forma visual les capacitats de CM d’acotar l’error de l’OF. A més a més de
les gràfiques descriptives, donada una gràfica representant la parella OF-CM,
donem una qualificació automàtica que categoritza la gràfica donat el tipus de
perfil.
• Metodologia estadística. Es proporciona una metodologia comparativa que
permet determinar quina és la millor parella OF-CM per a acotar l’error de
l’OF, aquesta metodologia consta de dues parts. Primer s’avalua el valor predictiu
de la CM mitjançant la gràfica descriptiva. Després, per a una mostra
de gràfiques descriptives calculades sobre unes seqüències de training, s’obté
una corba genèrica que es podrà fer servir per a seqüències que no tenen ground
truth. En el segon pas, s’avalua la corba genèrica obtinguda i les seves capacitats
per a reflectir el valor predictiu de la mesura de confiança mitjançant ANOVA’s.
La metodologia presentada mostra el potencial en aplicació clínica per a DSS. En
concret, s’ha analitzat l’impacte de diferents artefactes en la imatge com ara soroll o
deteriorament en el resultat final d’OF per a imatges del cor. També s’ha aplicat per
a millorar la navegació dintre l’arbre bronquial en una broncoscòpia.Optical Flow (OF) is the input of a wide range of decision support systems such as car driver assistance, UAV guiding or medical diagnose. In these real situations, the absence of ground truth forces to assess OF quality using quantities computed from either sequences or the computed optical flow itself. These quantities are generally known as Confidence Measures, CM. Even if we have a proper confidence measure we still need a way to evaluate its ability to discard pixels with an OF prone to have a large error. Current approaches only provide a descriptive evaluation of the CM performance but such approaches are not capable to fairly compare different confidence measures and optical flow algorithms. Thus, it is of prime importance to define a framework and a general road map for the evaluation of optical flow performance. This thesis provides a framework able to decide which pairs ”optical flow - con- fidence measure” (OF-CM) are best suited for optical flow error bounding given a confidence level determined by a decision support system. To design this framework we cover the following points: • Descriptive scores. As a first step, we summarize and analyze the sources of inaccuracies in the output of optical flow algorithms. Second, we present several descriptive plots that visually assess CM capabilities for OF error bounding. In addition to the descriptive plots, given a plot representing OF-CMcapabilities to bound the error, we provide a numeric score that categorizes the plot according to its decreasing profile, that is, a score assessing CM performance. • Statistical framework. We provide a comparison framework that assesses the best suited OF-CM pair for error bounding that uses a two stage cascade process. First of all we assess the predictive value of the confidence measures by means of a descriptive plot. Then, for a sample of descriptive plots computed over training frames, we obtain a generic curve that will be used for sequences with no ground truth. As a second step, we evaluate the obtained general curve and its capabilities to really reflect the predictive value of a confidence measure using the variability across train frames by means of ANOVA. The presented framework has shown its potential in the application on clinical decision support systems. In particular, we have analyzed the impact of the different image artifacts such as noise and decay to the output of optical flow in a cardiac diagnose system and we have improved the navigation inside the bronchial tree on bronchoscopy.
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Godoy, Ramirez Karina. "Flow cytometric methods for assessment of cell-mediated immune responses /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-409-0/.
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Jelly, Thomas. "A critical assessment of turbulent flow over textured superhydrophobic surfaces." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24113.
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Over the past century, a sustained effort has been expended on the research and development of surfaces that reduce the amount of drag experienced by a fluid as it passes by, motivated by both environmental and economic savings. Superhydrophobic surfaces have recently emerged as an attractive means to reduce the levels of skin-friction drag under both laminar and turbulent flow conditions. A superhydrophobic state is attained naturally or synthetically through a combination of surface topology and surface chemistry and can, in some cases, support a free-stress gas-liquid interface. In the presence of bulk fluid motion, the interfaces permit a finite slip velocity which has been credited to the reduction of the average wall shear stress. The fundamental drag reduction mechanism, however, remains unclear. In order to accurately resolve the full spectrum of turbulent scales, direct numerical simulations of fully turbulent channel flow over superhydrophobic textures at a friction Reynolds number of Reτ ≈ 180 were conducted. The instantaneous flow fields were subject to triple decomposition which permits statistical quantities to be accumulated in a phase-averaged form. From these phase-averaged statistics the mean, periodic and stochastic fluid motions can be considered independently. Following a detailed statistical analysis, the contributions of the mean, periodic and stochastic fluid motions towards the local levels of wall shear stress were determined by the derivation and evaluation of an appropriate skin-friction identity. In addition, a new modification to superhydrophobic surfaces is investigated by means of meandering the surface topology in the streamwise direction. Relative to a streamwise-aligned topology, it was anticipated that superior drag reduction would be achieved due to the addition of an oscillatory spanwise motion to the mean flow.
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Ghouth, Nahar Nizar A. "The assessment of pulpal blood flow using laser Doppler flowmetry." Thesis, University of Leeds, 2019. http://etheses.whiterose.ac.uk/22641/.
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Aims: The overall aim of this work was to study the use of Laser Doppler flowmetry for the assessment of the dental pulp in permanent teeth. The thesis is presented as four distinct studies; 1) A systematic review was carried out to assess the published evidence on the use of laser Doppler flowmetry in the assessment of the pulp status of permanent teeth, 2) A cross-sectional survey was carried out in order to understand the use of dental pulp tests by paediatric dentists and general dental practitioners in children with dental trauma in the United Kingdom, 3) The first clinical study aimed to assess whether laser Doppler flowmetry was more accurate than the conventional pulp sensibility tests (Electric pulp test and ethyl chloride) in assessing the pulp status of permanent anterior teeth in children, and 4) The second clinical study aimed to prospectively monitor pulp sensibility/vitality of traumatised teeth using laser Doppler flowmetry, electric pulp testing and ethyl chloride, and to prospectively investigate the accuracy of each test. Methods: Systematic review: A systematic literature search, using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, www.clinicaltrials.gov and www.controlled-trials.com, in addition to citation and manual reference list searches, was conducted up to 15th January 2018. A risk of bias assessment was performed using the quality assessment for diagnostic accuracy studies tool (QUADAS-2) with all steps performed independently by two reviewers. Survey: A cross-sectional study utilising an 18-item questionnaire that was developed using the Bristol Online Survey (BOS) tool and circulated electronically to the members of the British Society of Paediatric Dentistry between June and August 2017. Clinical study 1: A cross-sectional cohort diagnostic accuracy study with randomisation was carried out in 8-16-year-old children. Participants had one maxillary central or lateral incisor with either a completed root canal treatment or pulp extirpation and a contra-lateral tooth with vital pulp. The outcome measures included the cut-off threshold for LDF and the sensitivity, specificity and predictive values as well as the repeatability of each test. The Receiver Operating Characteristic (ROC) curve and the contingency 2X2 table were used for analysis. Kappa scores were used to assess the repeatability of EPT and ethyl chloride while inter-class correlation was used for LDF. Clinical study 2: Children who sustained dental trauma to an anterior permanent tooth with uncertain pulp vitality requiring monitoring for a minimum of 12 months were included in the study. Recordings of dental pulp tests were carried out at baseline and at the end of the follow-up period. Results Systematic review: Only four studies all with a high risk of bias were included in the final systematic review for analysis. Laser Doppler flowmetry was reported to be more accurate in differentiating between teeth with normal pulps and pulp necrosis with a sensitivity of (81.8-100%) and specificity of 100 % in comparison to other vitality tests such as pulp oximetry (sensitivity = 81.3 %, specificity = 94.9 % ) and sensibility tests such as electric pulp testing (EPT) (sensitivity = 63.3 - 91.5 %, specificity = 88 - 100 %). Survey: One hundred and forty-one respondents, both, paediatric dental specialists (56%) and GDPs (44%) were included in the analysis. Almost all specialists (93.7%) reported using sensibility tests routinely in comparison to 80.6% of GDPs. Child perception and cooperation were the most commonly reported barriers. GDPs mainly used cold testing, while specialists used cold and electric pulp tests equally. Inconsistencies in recording as well as documentation the results varied among respondents. Only a few specialists reported having some experience in using laser Doppler flowmetry. Clinical study 1: There was a significant difference between the Flux values for teeth with vital and non-vital pulps. The best cut-off ratio for LDF was 0.6 yielding a sensitivity of 54 % and a specificity of 32 % which were lower than the values of electric pulp test (Sensitivity = 83.8 - 94.6 %, Specificity = 89.2 - 97.6 %) and ethyl chloride (Sensitivity = 81.1 - 91.9 %, Specificity = 73 - 81.1 %). The repeatability of LDF, EPT and ethyl chloride were 0.85, 0.86 and 0.81, respectively. Clinical study 2: The study included a convenience sample size of 15 participants with a mean age of 10.7 years (SD=1.66), age range 8-14 years. The mean follow-up period was 7.29 months (SD 1.9) with a range of 6-12 months. All traumatised teeth remained vital at the end of follow-up except one tooth. The specificity of LDF at baseline was 80% compared to 66.6% and 60-73.3% for EPT and ethyl chloride, respectively. At the end of the follow-up period, LDF showed lower specificity (71.4 %) than EPT (78.5 - 85.7 %) and ethyl chloride (71.4 - 78.5 %). Conclusion: Despite the high reported sensitivity and specificity of laser Doppler flowmetry in the systematic review, these data were found to be based on studies with a high level of bias and serious shortfalls in study designs. The survey of specialists and GDP's showed that the use of pulp sensibility tests was relatively high amongst respondents while those of vitality tests were very low. Barriers and inconsistencies in the technique and recording of the results of sensibility tests were evident. The frequency and timing of using sensibility tests in line with international guidelines were stressed. The use of standardised techniques involving methods considered to improve reliability was highlighted. The results of the clinical studies showed that there was a high probability of false results when using LDF in assessing the pulp blood flow/pulp vitality. LDF was unable to differentiate between teeth with vital and non-vital pulps in children between the ages of 8-16 years with an acceptable level of confidence in the first clinical study. Within the limitations of the second clinical study, LDF showed better specificity than both EPT and ethyl chloride in predicting the outcome of the pulp at baseline but less at the end of follow-up. Due to the small sample size and relatively short follow-up period, the results of the second clinical study have been interpreted with caution. Therefore, the published data on the accuracy of LDF can not be accepted as they are based on studies with unacceptable flaws in study design. Our studies have shown that not only the use of LDF or even the experience of clinicians with its use is extremely low, but also its specificity and sensitivity were of a level which is unacceptable for recommending its meaningful clinical use.
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Tse, Rosanna. "A critical assessment of two phase flow characterization of soil." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/28178.
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McParland, Daniel. "Empirical in-stream flow assessment tools for British Columbian channels." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45054.
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Empirical hydraulic distribution equations have been proposed as simple and inexpensive alternatives to traditional data-intensive flow assessment methodologies. Two proposed depth and three proposed velocity empirical equations were compared to measured hdraulic distributions for two channels in the Interior Region of British Columbia. Empirical velocity distributions adequately reproduced the measured velocity distribution for both channels. An empirical depth distribution was able to replicate measured depth distributions at a relatively undisturbed channel (Harris Creek) but were unable to predict the measured depth distribution following morphological change at a channel recently disturbed by forest fire (Fishtrap Creek). Furthermore, the empirical distributions were compared to modelled depth and velocity distributions produced by a 2-dimensional hydrodynamic model (River2D). The empirical distributions provided reasonable representation of the hydraulic distributions for flows < 3 m³ s-¹. At flows approaching bankfull the empirical methods, in particular the velocity equations, were unable to adequately reproduce the distributions produced in River2D. Additionally, a joint frequency depth-velocity distribution was paired with habitat suitability indices to quantify available habitat across a range of flows at Harris Creek using reach average hydraulic conditions generated by River2D. The statistical habitat model produced similar habitat values to River2D at low flows and was able to recreate the general shape and trends of the habitat indices. As well, a proposed at-a-station hydraulic geometry simulator was used alongside a channel regime model to approximate reach average channel conditions at Harris Creek. The proposed hydraulic simulator was able to accurately predict reach average depth (mean error of 1.06 %) and velocity (4.47 %) for discharges ranging from daily low flow to bankfull flow. The hydraulic simulator was coupled with the statistical habitat model to generate hydraulic distributions and subsequently habitat indices for the modelled discharges. The incorporation of the regime models allows users to examine the influence of variable flow regimes and riparian vegetation (inherent of a changing climate) on available aquatic habitat. The proposed aquatic habitat model provides practitioners with a low-input, user-friendly flow assessment tool that can be used for preliminary habitat assessments and basin-wide habitat studies in British Columbia.
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Aderinlewo, Olufikayo Oluwaseun. "Assessment of a transportation infrastructure system and its component interactions." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 378 p, 2008. http://proquest.umi.com/pqdweb?did=1617913671&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Keegan, Jennifer. "MR coronary artery imaging : assessment and implications of flow and motion." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342262.
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Yang, David S. M. Massachusetts Institute of Technology. "Experimental assessment of the internal flow behavior of supercritical carbon dioxide." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93803.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-121).
This thesis presents an experimental assessment of the internal flow behavior of supercritical carbon dioxide. The investigation focused mainly on assessing condensation onset during rapid expansion of CO₂ into the two-phase region. An experimental blowdown test-rig with a modular test section was developed with the capability of operating a converging-diverging nozzle with a wide range of charge conditions. The test-rig demonstrated repeatable results with relative errors of less than 1 percent. An innovative method to measure the speed of sound through the use of Helmholtz resonators was developed and investigated. Shock tube experiments and static high pressure air tests in the blowdown facility were conducted to determine the viscous damping in the resonators. The results indicate that a Helmholtz resonator neck Reynolds number of 106 is required for underdamped response. The speed of sound measurement technique was demonstrated at relevent Reynolds numbers and at static conditions in air, showing promise for blowdown testing in S-CO₂ Blowdown experiments were conducted in supercritical CO₂ from charge conditions both away and near the critical point to sonic conditions in the two-phase region. To determine whether there was condensation onset, static pressure measurements were compared to theoretical and numerical models. Numerical models utilized the Span-Wagner equation of state extrapolated into the two-phase region to characterize the metastable state. Away from the critical point, for operating conditions typically encountered in S-CO₂ compressor stages, condensation was not observed. Near the critical point, results were inconclusive and future work is proposed to provide more conclusive assessment of condensation near the critical region.
by David Yang.
S.M.
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Igwe, Ogbonnaya. "Assessment of flow slide initiation and motion in variably graded sands." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144189.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第12106号
理博第3000号
新制||理||1447(附属図書館)
23942
UT51-2006-J101
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 佐々 恭二, 教授 千木良 雅弘, 教授 橋本 学
学位規則第4条第1項該当
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Kanta, Lufthansa Rahman. "Vulnerability assessment of water supply systems for insufficient fire flows." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1084.
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Ryan, Thomas Michael 1963. "A laboratory assessment of flow characteristics and permeability of fractures in rock." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276629.
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Intact and fractured rock samples were studied in the laboratory in order to understand more fully the mechanism of closure of fractures subjected to high confining stresses and the resultant effect on specimen permeability. Confining stresses applied to the specimens ranged from 3.0 to 20.0 MPa, and the closure of fractures was observed by monitoring the change in the hydraulic conductivity of the specimens. Test results suggest that some resealing may occur due to crushing and realignment of mineral grains along a fracture surface. The closure of fractures is dependent upon the strength of the rock mass, the physical nature of the fracture, and the fluid pressure present in the fracture. Fracture closure is highly time dependent, and a number of nonlinear pressure flow relationships have been identified. These deviations are thought to represent two fundamentally different processes, the most important of which are turbulence in the flow and fracture expansion.
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Farnebo, Simon. "On microvascular blood flow assessment with the new microdialysis urea clearance technique." Doctoral thesis, Linköpings universitet, Hand och plastikkirurgi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63116.
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The aim of this thesis was to develop and evaluate a new way of monitoring blood flow with microdialysis. A thin catheter consisting of a semipermeable membrane is implanted in the tissue being studied. The catheter is perfused by a solution that closely resembles interstitial fluid, and small water-soluble substances are allowed to diffuse passively through the pores of the membrane with the aim at reaching equilibrium with the surrounding tissue. The minimally invasive character of microdialysis, and its ability to sample from the organ being studied, make microdialysis attractive in most research settings as well as for clinical surveillance. It has, however, become increasingly evident that microdialysis under conditions of non-equilibrium - for example, fluctuating regional blood flow, will alter the results gained. We have therefore aimed to explore the possibilities of developing a new marker of blood flow that will yield information about changes in blood flow that occur in the area of the microdialysis catheter itself. We hypothesised that the changes in the diffusion of exogenous urea could be used as markers of changes in tissue blood flow. The theoretical basis for this approach is that the mass transfer of urea will increase across the dialysis membrane secondary to increased blood flow. As removal of urea from the vicinity of the dialysis membrane increases with increased blood flow, the concentration gradient of urea between the perfusate and tissue will also increase. This in turn will result in a greater loss of urea from the perfusate. The changes noted in retrieval of urea from dialysate by the system are therefore thought to be inversely related to changes in blood flow. We tested our hypothesis in two species of animal (rat and pig) and in man, and in three organ systems (muscle, liver, and skin), and present four papers that indicate that the urea clearance technique provides reliable and reproducible results. The technique was evaluated against conventional metabolic markers (lactate and glucose), the ethanol clearance technique (microdialysis), laser Doppler perfusion imaging (LDPI), and polarisation light spectroscopy (TiVi). We present evidence that the urea clearance technique can be used to assess blood flow in the organs studied reliably and reproducibly with microdialysis. The microdialysis technique is minimally invasive and safe for the recipient, and catheters can easily be implanted during operation to monitor organs at risk. Urea is easily analysed as a standard assay among other “basic” metabolic markers (in a standard microdialysis kit) and has favourable characteristics with a standardised measurement system that is routinely used for monitoring metabolites in the clinic. The technique is also effective when used at lower perfusate flow rates (<1 μl/minute), which is advantageous as the recovery of metabolic markers increases at low perfusate flow rates.
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Uwayigira, Vedaste. "Assessment of Communication and Information flow between Trondheim Municipality and international employees." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for sosiologi og statsvitenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13121.
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This study is an examination of communication channels that are most relevant and appropriate for communication and information flow between Trondheim Municipality as a local authority and international employees who benefit the municipal services as part of its residents. The study seeks to assess the effectiveness of the existing communication channels and suggest possible ways of improving the communication and information flow between the source and the recipient. The theoretical framework applies two bodies of theories in social science, predominantly emphasizing on globalization and communication theories. These two theories are chosen to illustrate the way in which Trondheim Municipality seeks to provide a reliable means of communication to integrate the foreign employees who stay and work in the community; therefore, the two theories would form the basis of the study. The study was carried out in Trondheim, Mid-Norway. The eight respondents were selected from five organisations/ companies located in Trondheim which are NTNU, Statoil, SINTEF, ACUSTO and ATMEL Norway. The respondents were professionals from the scientific disciplines of engineering, geology, hydrology, researcher, and geophysicist. They were interviewed using semi-structured interviews. Thus, the current study examines the communication channels which are used by Trondheim Municipality that include internet, electronic mail, face-to-face communication, telephone, postal mails, brochures and booklets. The findings of the study indicated that most of information needed by the respondents was obtained from the internet. Subsequently, in order to improve communication between Trondheim Municipality and international employees, it was suggested that, the information regarding municipal services should be publicized at the strategic contact points such as police and tax office. The study concludes that generally the communication and information flow between Trondheim Municipality and international employees can be better enhanced using various modern information and communication technologies such as internet and conveyed through major world languages at various points of entry and contact offices providing the essential services that cater for an international workforce at the onset of their arrival in the area.
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García-Blanco, Raquel. "Efficient solvers for power flow equations : parametric solutions with accuracy control assessment." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/458887.
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The Power Flow model is extensively used to predict the behavior of electric grids and results in solving a nonlinear algebraic system of equations. Modeling the grid is essential for design optimization and control. Both applications require a fast response for multiple queries to a parametric family of power flow problems. Different solvers have been introduced especially designed for the algebraic nonlinear power flow equations, providing efficient solutions for single problems, even when the number of degrees of freedom is considerably large. However, there is no existing methodology providing an explicit solution of the Parametric Power Flow problem (viz. a computational vademecum, explicit in terms of the parameters).
This work aims precisely at designing algorithms producing computational vademecums for the Parametric Power Flow problem. Once these solutions are available, solving for different values of the parameters is an extremely fast (real-time) post-process and therefore both the optimal design and the control problem can readily be addressed.
In a first phase, a new family of iteratives solvers for the non-parametric version of the problem is devised. The method is based on a hybrid formulation of the problem combined with an alternated search directions scheme. These methods are designed such that it can be generalized to deal with the parametric version of the problem following a Proper Generalized Decomposition (PGD) strategy.
The solver for the parametric problem is conceived by performing the operations involving the unknowns in a PGD fashion. The algorithm follows the basic steps of the algebraic solver, but some operations are carried out in a PGD framework, that is requiring a nested iterative algorithm. The PGD solver is accompanied with an error assessment technique that allows monitoring the convergence of the iterative procedures and deciding the number of terms required to meet the accuracy prescriptions. Different examples of realistic grids and standard benchmark tests are used to demonstrate the performance of the proposed methodologies.El modelo de flujo de potencias se usa para predecir el comportamiento de redes eléctricas y desemboca en la resolución de un sistema de ecuaciones algebraicas no lineales. Modelar una red es esencial para optimizar su diseño y control. Ambas aplicaciones requieren una respuesta rápida a las múltiples peticiones de una familia paramétrica de problemas de flujo de potencias. Diversos métodos de resolución se diseñaron especialmente para resolver la versión algebraica de las ecuaciones de flujo de potencias. Sin embargo, no existe ninguna metodología que proporcione una solución explícita al problema paramétrico de flujo de potencias (esto quiere decir, un vademecum computacional explícito en términos de los parámetros). Esta tesis tiene como objetivo diseñar algoritmos que produzcan vademecums para el problema paramétrico de flujo de potencias. Una vez que las soluciones están disponibles, resolver problemas para diferentes valores de los parámetros es un posproceso extremadamente rápido (en tiempo real) y por lo tanto los problemas de diseño óptimo y control se pueden resolver inmediatamente. En la primera fase, una nueva familia de métodos de resolución iterativos para la versión algebraica del problema se construye. El método se basa en una formulación híbrida del problema combinado con un esquema de direcciones alternadas. Estos métodos se han diseñado para generalizarlos de forma que puedan resolver la versión paramétrica del problema siguiendo una estrategia llamada Descomposición Propia Generalizada (PGD). El método de resolución para el problema paramétrico calcula las incógnitas paramétricas usando la técnica PGD. El algoritmo sigue los mismo pasos que el algoritmo algebraico, pero algunas operaciones se llevan a cabo en el ambiente PGD, esto requiere algoritmos iterativos anidados. El método de resolución PGD se acompaña con una evaluación del error cometido permitiendo monitorizar la convergencia de los procesos iterativos y decidir el número de términos que requiere la solución para alcanzar la precisión preescrita. Diferentes ejemplos de redes reales y tests estándar se usan para demostrar el funcionamiento de las metodologías propuestas.
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Hamm, Christopher Eric. "AN ASSESSMENT OF FLOW QUALITY IN AN OPEN TEST SECTION WIND TUNNEL." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11022009-115210/.
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The subsonic wind tunnel facility at Mississippi State University has been converted to an open test section configuration. An experimental setup was developed which is easily configurable to allow for further research. Measurements of flow quality over select portions of the test section were made to attain a basic understanding of the performance of the new configuration. A program was developed in LabVIEW to control a 3-axis traverse and perform necessary data reduction. The traverse control program was developed to perform data acquisition using a hot-film probe to facilitate the necessary measurements. Data was gathered at two wind tunnel velocity settings over several test section locations. Results of the testing program yielded recommendations on the use of the open configuration. This paper documents the procedure and setup of the testing program to include discussion of the control/data acquisition program and a discussion of the findings and recommendations.
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Levering, Wilfridus Henricus Bernardus Maria. "External quality assessment in flow cytometry educational aspects and trends toward improvement /." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10602.
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Mastorakou, Irene. "Duplex Doppler ultrasound in the clinical assessment of the renal blood flow." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314900.
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Adeloye, A. J. "Value of river flow data for water resources and water quality assessment." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378277.
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SOTOMAYOR, JAVIER ORTEGA. "INTERDEPENDENCE OF VOLTAGE CONTROL EQUIPMENTS: COHERENCY ASSESSMENT IN THE POWER FLOW PROBLEM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20273@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Com o aumento do número de dispositivos de controle representados nos casos práticos, pode ser verificado o aparecimento de interações entre suas ações de controle. Quando estas interações não são coordenadas podem ocasionar a diminuição da eficiência do método de Newton-Raphson no problema de fluxo de potência, resultando em convergências lentas e frequentemente soluções oscilatórias ou até mesmo a divergência do método. Uma adequada identificação destas interações pode contribuir para tomar as medidas corretivas necessárias e assim evitar este tipo de problema. Com esse objetivo, identificam-se as interações entre múltiplos dispositivos de controle (mais de dois equipamentos de controle) a partir da análise dos autovalores e fatores de participação da matriz de sensibilidade de controles denominada [MSC]. Esta matriz, elaborada com base num modelo alternativo para a representação do controle de tensão local das barras PV, é obtida da redução da matriz Jacobiana expandida do problema de fluxo de potência. Dentro deste contexto, se verifica a presença de autovalores que apresentam informações similares sobre os dispositivos de controle com fortes interações entre suas ações de controle, desenvolvendo-se assim, um método baseado no conceito de colinearidade capaz de identificar e agrupar estes autovalores. Os resultados da avaliação do método desenvolvido aplicado em sistemas de pequeno e grande porte mostram a relevância e a viabilidade da utilização prática dos desenvolvimentos propostos neste trabalho.
The increasing number of control devices represented in practical cases, we can see the appearance of interactions between their control actions. When these interactions are not coordinated (conflict), the efficiency of Newton- Raphson method decrease to the power flow problem, the convergence is slow and the solutions are oscillatory. A correct identification of these interactions can help to take corrective actions and thus avoid this problem. With this objective, the identification of interactions between control devices (more than 2 control equipment) is established from the modal analysis of the sensitivity matrix [MSC]. This sensitivity matrix [MSC] is developed in based to alternative model to represent the local voltage control of the PV buses. This [MSC] is obtained from the reduction of the Jacobean matrix expanded of power flow problem. Within this context, it also checks for the presence of eigenvalues that have similar information about the significant interactions between control devices, thus developing a method based on the use index of sensitivity matrix [MSC] and concept of collinearity able to identify and group these eigenvalues. The results of the evaluation method applied to systems designed for small and large show the relevance and feasibility of practical use of proposed developments in this work.
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Larsson, Annika (Annika S. ). "Evaluation of flow battery technology : an assessment of technical and economic feasibility." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54555.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 89-90).
Energy storage has been a topic of recent political discussions. There is interest in utilizing energy storage technologies to improve the emissions and "green" the environment. Many of the energy storage technologies have been around for many decades; however, there is often little research done into the analysis of the economic and technical feasibility of these technologies. This study aims to assess the feasibility of flow batteries for both large and small scale energy storage applications. Applications for larger scale storage must meet the price point set out by utilities of $1000/kW all inclusive. Additionally, getting prices below $200/kWh is important in order to have a technology be likely to receive attention and interest from utilities and larger companies. This study breaks down the cost of the Zinc Bromine flow battery in order to assess the current cost and predictions for the future. In addition to assessing the cost, this study analyses the performance of the Zinc Bromine battery and determines for which applications and markets the Zinc Bromine battery is best suited.
by Annika Larsson.
M.Eng.
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Seyed, Jabbari Seyed Shervin. "Phytoremediation efficiency: assessment of flow system and plant performance in constructed wetland." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Water is one of the most basic human needs for survival, though, there is a shortage in the amount of drinking water around the globe. Thus, preserving the quality of available water should be of high importance for us. For this purpose, we must treat water, used in every aspect of human activity, before releasing it back to the water bodies. With an increased inclination towards sustainability and green technologies, Constructed Wetlands (CW) are getting more attention as a more eco-friendly treatment for wastewater rather than conventional treatment plants.
There are different types of CW operating around the world with a different typology of plants vegetated in them. The aim of this Thesis is to compare these differences to find the best combination for improving CW performance for wastewater treatment. Different case studies throughout Italy have been examined for this matter. Many of these cases, used Hybrid CW rather than a single stage of either Vertical Subsurface Flow CW (VSSF) or Horizontal Subsurface Flow CW (HSSF), and usually, there is a Floating Treatment Wetland (FTW) as a tertiary step for further refining water quality before releasing it. This kind of Treatment setup for CWs shows an increased abatement efficiency for wastewater.
Lastly, vegetations in CW usually improve the efficiency of wetland performance. The important parameters in selecting macrophytes are their survivability and adaptability in wetland conditions. Among the macrophytes encountered Phragmites Australis and Iris Pseudacorus generally showed a higher growth performance and more adaptability in CW conditions.
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Okell, Thomas William. "Assessment of collateral blood flow in the brain using magnetic resonance imaging." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:7e63bcf2-22bf-49e5-81ec-1644217605ae.
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Collateral blood flow is the compensatory flow of blood to the tissue through secondary channels when the primary channel is compromised. It is of vital importance in cerebrovascular disease where collateral flow can maintain large regions of brain tissue which would otherwise have suffered ischaemic damage. Traditional x-ray based techniques for visualising collateral flow are invasive and carry risks to the patient. In this thesis novel magnetic resonance imaging techniques for performing vessel-selective labelling of brain feeding arteries are explored and developed to reveal the source and extent of collateral flow in the brain non-invasively and without the use of contrast agents. Vessel-encoded pseudo-continuous arterial spin labelling (VEPCASL) allows the selective labelling of blood water in different combinations of brain feeding arteries that can be combined in post-processing to yield vascular territory maps. The mechanism of VEPCASL was elucidated and optimised through simulations of the Bloch equations and phantom experiments, including its sensitivity to sequence parameters, blood velocity and off-resonance effects. An implementation of the VEPCASL pulse sequence using an echo-planar imaging (EPI) readout was applied in healthy volunteers to enable optimisation of the post-labelling delay and choice of labelling plane position. Improvements to the signal-to-noise ratio (SNR) and motion-sensitivity were made through the addition of background suppression pulses and a partial-Fourier scheme. Experiments using a three-dimensional gradient and spin echo (3D-GRASE) readout were somewhat compromised by significant blurring in the slice direction, but showed potential for future work with a high SNR and reduced dropout artefacts. The VEPCASL preparation was also applied to a dynamic 2D angiographic readout, allowing direct visualisation of collateral blood flow in the brain as well as a morphological and functional assessment of the major cerebral arteries. The application of a balanced steady-state free precession (bSSFP) readout significantly increased the acquisition efficiency, allowing the generation of dynamic 3D vessel-selective angiograms. A theoretical model of the dynamic angiographic signal was also derived, allowing quantification of blood flow through specified vessels, providing a significant advantage over qualitative x-ray based methods. Finally, these methods were applied to a number of patient groups, including those with vertebro-basilar disease, carotid stenosis and arteriovenous malformation. These preliminary studies demonstrate that useful clinical information regarding collateral blood flow can be obtained with these techniques.
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Jonasson, Hanna. "Model-based quantitative assessment of skin microcirculatory blood flow and oxygen saturation." Doctoral thesis, Linköpings universitet, Biomedicinsk instrumentteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-127691.
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The microcirculation, involving the smallest vessels in the body, is where the oxygen transport to all tissue occurs. Evaluating microcirculatory parameters is, therefore, important and involves the quantification of oxygen content of red blood cells (RBCs), the amount of RBCs and their speed. Diffuse reflectance spectroscopy (DRS) can be used to estimate blood oxygen saturation and fraction of RBCs in tissue since oxygenated and deoxygenated blood have different light absorption characteristics. By illuminating the skin with white light and detecting the spectrum of the backscattered light, tissue absorption and scattering can be assessed. Laser Doppler flowmetry (LDF) is a technique to measure blood flow in tissue. When laser light encounter moving objects in tissue, i.e. RBCs, the light is Doppler shifted, which can be detected and used to calculate tissue perfusion (the fraction of moving RBCs times their speed). With a small distance between light source and detector, both techniques measure superficially where most vessels are microcirculatory vessels. Photon transport in tissue can be simulated with Monte Carlo techniques and the simulations form the basis of modeled DRS and LDF spectra. The estimated microcirculatory parameters are given by the model that best describe measured DRS and LDF data. This thesis describes the development and the evaluation of an optical method to simultaneously measure oxygen saturation, RBC tissue fraction and speed resolved perfusion in absolute units by integrating DRS and LDF. By combining DRS and LDF into one system with a common tissue model, the two modalities can benefit from each other’s strengths. Different calibration methods and model assumptions for the system were evaluated in optical phantoms and in skin measurements. A simple calibration method with two detector distances for DRS was found adequate to accurately estimate absorption and scattering in optical phantoms. It was also necessary to model blood located in vessels, rather than homogeneously distributed in the skin, to obtain accurate parameter estimates. The system was evaluated in healthy subjects during standard provocations, where the parameters were in agreement with other studies and followed an expected pattern during the provocations. In patients with diabetes type 2, tissue fraction of RBCs and nutritive blood flow were reduced in baseline compared to healthy controls. These differences were not related to prevalence of microalbuminuria, a marker sign of microvascular complications in the kidneys. A combined system with DRS and LDF enables a more comprehensive assessment of the microcirculation by measuring oxygen saturation, RBC tissue fraction and speed resolved perfusion simultaneously and in absolute units. This system has clinical potential to assist in the evaluation of the microcirculation both in healthy and diseased individuals.Mikrocirkulationen innefattar de minsta kärlen i kroppen och det är här syretransporten till all vävnad i kroppen sker. Det är därför viktigt att kunna utvärdera mikrocirkulatoriska parametrar såsom syresättningen hos de röda blodkropparna, mängden röda blodkroppar samt deras hastighet. Diffus reflektansspektroskopi (DRS) kan användas för att beräkna syresättningen i blodet och mängden röda blodkroppar eftersom syresatt blod har ett karaktäristiskt sätt att absorbera ljus. Absorptionen och spridningen i vävnaden kan skattas genom att belysa huden med vitt ljus och mäta spektrumet från det tillbakaspridda ljuset. Laserdopplerbaserad flödesmätning (LDF) är en teknik som mäter blodflöde i vävnad. När laserljus träffar objekt i vävnaden som rör sig, t.ex. röda blodkroppar, så uppstår Dopplerskift. Dessa Dopplerskift kan detekteras och ett perfusionmått för vävnaden (mängden röda blodkroppar i rörelse gånger deras hastighet) kan beräknas. Med små avstånd mellan ljuskälla och detektor kan båda teknikerna mäta ytligt där den största delen av kärlen tillhör mikrocirkulationen. Fotontransporten i vävnad kan simuleras med Monte Carlo-teknik och simuleringarna ligger till grund för att modellera DRS- och LDF-spektra. De mikrocirkulatoriska parametrarna ges från den modellen som bäst passar DRS- och LDF-data. Avhandlingen beskriver utvecklingen och utvärderingen av en optisk metod för att simultant mäta syresättningen, mängden röda blodkroppar och hastighetsupplöst perfusion i absoluta enheter genom att integrera DRS och LDF. Genom att kombinera DRS och LDF i ett system med en gemensam hudmodell kan de två modaliteterna dra nytta av varandras styrkor. Olika kalibreringsmetoder och modellantaganden för systemet utvärderades i optiska fantomer och i hudmätningar. En enkel kalibreringsmetod med två detektoravstånd för DRS visade sig vara tillräckligt för att kunna skatta absorption och spridning i optiska fantomer. Det var också nödvändigt att modellera blod i kärl istället för homogent fördelat i huden för att uppnå noggranna parameterskattningar. Systemet utvärderades under standardprovokationer på friska försökspersoner där parametrarna stämde överens med andra studier och följde ett förväntat mönster under provokationerna. Hos patienter med diabetes typ 2 sågs en minskad mängd röda blodkroppar och kapillärt blodflöde i oprovocerad hud jämfört med friska kontroller. Skillnaden var inte kopplad till förekomsten av mikroalbuminuri, ett tecken på mikrovaskulära komplikationer i njurarna. Ett kombinerat system med DRS och LDF ger en mer fullständig bild av mikrocirkulationen genom att samtidigt och i absoluta enheter mäta syresättningen, mängden röda blodkroppar och hastighetsupplöst perfusion. Systemet kan användas för att utvärdera mikrocirkulationen både hos friska och sjuka individer.
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Chu, Wui-cheung Tommy. "Determination of design magnitude of debris flow hazard for mitigation measures in Hong Kong." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B43895621.
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Ensley, Ann Elizabeth. "A fluid mechanic assessment of the total cavopulmonary connection." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15724.
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Duttagupta, Suchismita Sujaya. "A reliability assessment methodology for distribution systems with distributed generation." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3851.
Full textAbstract:
Reliability assessment is of primary importance in designing and planning distribution
systems that operate in an economic manner with minimal interruption of
customer loads. With the advances in renewable energy sources, Distributed Generation
(DG), is forecasted to increase in distribution networks. The study of reliability
evaluation of such networks is a relatively new area. This research presents a new
methodology that can be used to analyze the reliability of such distribution systems
and can be applied in preliminary planning studies for such systems. The method uses
a sequential Monte Carlo simulation of the distribution systemÂs stochastic model to
generate the operating behavior and combines that with a path augmenting Max flow
algorithm to evaluate the load status for each state change of operation in the system.
Overall system and load point reliability indices such as hourly loss of load, frequency
of loss of load and expected energy unserved can be computed using this technique.
On addition of DG in standby mode of operation at specific locations in the network,
the reliability indices can be compared for different scenarios and strategies for
placement of DG and their capacities can be determined using this methodology.
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Reidy, Liermann Catherine. "Ecohydrologic impacts of dams : A global assessment." Doctoral thesis, Umeå : Department of Ecology and Environmental Science, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1394.
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Assefa, Getachew. "On sustainability assessment of technical systems : experience from systems analysis with the ORWARE and EcoEffect tools /." Doctoral thesis, Stockholm : Division of Industrial Ecology, Deparment of Chemical Engineering, School of Chemical Science and Engineering, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-550.
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Fothergill, Catriona E. "The role of computational fluid dynamics in predicting atmospheric flow and dispersion in the petrochemical industry." Thesis, University of Surrey, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250858.
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Hagblad, Jimmie. "Non-invasive techniques for assessment of peripheral blood flow at different vascular depths." Licentiate thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-12226.
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Missing or reduced blood flow can lead to pressure ulcers. Monitoring blood flow in areas prone to pressure ulcer development would be a valuable tool for prevention of pressure ulcers. PPG and LDF are both established non invasive optical techniques that can be used to estimate the changes in blood flow in different tissue volumes. The aim of this thesis was to combine the established techniques, LDF and PPG, into one flexible silicon probe intended for evaluation of peripheral blood flow in tissue volumes prone to pressure ulcer development. Further, a temperature sensor was integrated. Two probe configurations combining LDF and PPG has been evaluated regarding the ability to separate between shallow, medium and deep blood flow variations, and skin temperature changes. Further, techniques to reduce or totally avoid interference between LDF and PPG have been investigated. The probes can be used to discriminate between blood flows at different vascular depths. The vascular depths reached by the different channels correspond to the depths of interest when investigating pressure ulcer aetiology. The probe itself has shown not to affect the skin surface temperature, neither due to the silicon sheet or the light. The skin temperature can be expected to rise and approach the body core temperature by lying in supine position alone, which has to be taken into consideration when designing studies. By switching between the different light sources, interference can be totally avoided. When rapid blood flow variations at several vascular depths are of interest to evaluate, a peripheral placement of the LDF-fibre and an increased illumination power of the PPG-LEDs might be used to minimize the interference between LDF and PPG. Both probes have shown potential to be used for investigation of the processes in pressure ulcer development.
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de, Macedo Soares Pires Condeixa Karina. "Material Flow Analysis and environmental impacts assessment of the construction sector in Brazil." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/454715.
Full textAbstract:
L'ampli ús de materials als edificis contribueix a l'escassetat de recursos naturals i a l'abocament de residus al medi
ambient. L'Anàlisi del Flux de Materials (MFA) s'ha utiliyat com a eina per aconseguir a desmaterialització i la
sostenibilitat dels edificis existents. Aquesta tesi s'organitza en tres capitols principals. El primer capitol presenta una
revisi bibliogràfica i un anàlisi bibliometric per recolyar lus sistematic de MFA. El segon capitol proposa un metode
basat en el MFA per a modelar la poblacio dels edificis residencials a la ciutat de Rio de Janeiro i el flux de materials
de residus, per tal de caracteritzar lstock d'edificis. El tercer capitol introdueix lus combinat de les metodologies
d'Anàlisi de Ciclo de Vida i MFA per a modelar els fluxos residuales de la poblacio d'edificis i per a avaluar els seus
impactes de cicle de vida. En resum, aquesta tesi explora les variants de la metodologia d'Anàlisi de Flux de Materials
i promou un ampli anàlisi dels edificis i dels impactes de cicle de vida dels fluxos de residus.El amplio uso de materiales en los edificios contribuye a la escasez de recursos naturales y al vertido de residuos en el medio ambiente. El Análisis del Flujo de Materiales (MFA) se ha utilizado como una herramienta para lograr la desmaterialización y la sostenibilidad de los edificios existentes. Esta tesis se organiza en tres capitulos principales. El primer capítulo presenta una revisión bibliográfica y un análisis bibliométrico para apoyar el uso sistemático del MFA. El segundo capítulo propone un método basado en el MFA para modelar la población de los edificios residenciales en la ciudad de Río de Janeiro, y el flujo de materiales y de residuos, con el fin de caracterizar el stock de edificios. El tercer capítulo introcuce el uso combinado de las metodologías de Análisis de ciclo de Vida y MFA para modelar los flujos residuales de la población de edificios y para evaluar sus impactos. En resumen, esta tesis explora las variantes de la metodología de Análisis de Flujo de Materiales y promueve un amplio análisis de los edificios y de los impactos del ciclo de vida de los flujos de residuos.
The extensive use of materials in buildins stocks contributes to the scarcity of natural resources and waste disposal on the environment. Material Flow Analysis (MFA) has been used as a tool to achieve dematerialization and sustainability of buildings stocks. This thesis is organized in three main chapters. The first chapter presents a literature review and a bibliometric analysis for supprting the systematic use of MFA. The second chapter proposes a method based on MFA to model the residential building stock in the city of Rio de Janeiro and their material and waste flows, in order to characterize the stock. The third chapter introduces the combinated use if MFA and Life Cycle Assessment methodologies to model waste flows from a building stock and to assess its life cycle impacts. In summary, this Thesis explores the variants of the MFA and promotes a broadly analysis of a building stocks and life cycle impacts from waste flows.
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Perkiö, Mattias. "Assessment of Pulse Wave Velocity in the Aorta by using 4D Flow MRI." Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110836.
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The purpose of this master thesis was to evaluate the estimation of pulse wave velocity (PWV) in the aorta using 4D flow MRI. PWV is the velocity of the pressure wave generated by the heart during systole and is a marker of arterial stiffness and a predictor of cardiovascular disease (CVD). PWV can in principle be estimated based on the time (travel-time) it takes for the pulse wave to travel a fixed distance (travel-distance), or based on the distance the pulse wave travels during a fixed time. In the commonly used time-to-travel-a-fixed-distance approach, planes are placed at two or more locations along the aorta. The travel-time is found by studying velocity waveforms at these pre-defined locations over time and thereby by estimating the time-difference for the pressure wave to reach each of these locations. In the distance-travelled-in-a-fixed-time approach, the pulse wave is located by studying at the velocity along the aorta at pre-defined instances in time. The travel-distance for the pulse wave between two instances in time is set as the difference in location of the pulse wave, where the location is identified as the location when the velocity has reached a predefined baseline. The specific aims of this thesis was to investigate the effect of using multiple locations as well as the effects of temporal and spatial resolution in the time-to-travel-a-fixed-distance approach, and to evaluate the possibility of using the distance-travelled-in-a-fixed-time approach. Additionally, the possibility of combining the two approaches was investigated. The study of using multiple locations revealed that more planes reduces the uncertainty of PWV estimation. Temporal resolution was found to have a major impact on PWV estimation, whereas spatial resolution had a more minor effect. A method for estimating PWV using 4D flow MRI using the distance-travelled-in-a-fixed-time approach was presented. Values obtained were compared favourably against previous findings and reference values, in the case of healthy young volunteers. The combination of the time-to-travel-a-fixed-distance and distance-travelled-in-a-fixed-time approaches appears feasible.
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Mould, David Charles. "Field and model assessment of the ecological impacts of redesigning compensation flow releases." Thesis, Durham University, 2007. http://etheses.dur.ac.uk/2573/.
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Rivers around the world have been regulated for a variety of reasons. Historically the flows released from these reservoirs have been set with minimal attention to ecology. The aim of this study was to use both field and modelling techniques to assess the ecological implications for altering compensation flow regimes in upland millstone grit catchments. A simple paired-catchment approach was chosen. The study catchments used were the regulated Rivelin and Loxley (tributaries of the River Don), and the unregulated Hipper. Before the 1st of April 2004， the steady state compensation releases from the Rivelin and Loxley were set at 2,6 Thousand Cubic Metres per Day (TCMD) and 28 TCMD respectively. After the Ր՛ of April 2004 the compensation flows were altered on the Rivelin and Loxley to 8.6 TCMD and 22 TCMD. This study used three broad scales of enquiry: macroinvertebrates; fisheries and modelling. Detailed macroinvertebrate surveys were conducted over a four year period (2002-2005), with samples taken in the spring, summer and autumn of each of those years. Surber samples were taken, along with associated environmental variables. Data analysis was conducted using both univariate and multivariate techniques. The invertebrate results showed that the role of flow variability is key within both of the regulated systems. The influence of flow variability is different on each of the study rivers, and the influence changes due to the alteration in compensation flows. Fisheries surveys were also conducted over this four year study period (2002-2005). Nine sites were surveyed yearly on the Rivelin and Loxley; and three on the Hipper. The fish populations in each of the rivers are dominated by brown trout (Salmo trutta). The importance of the interaction of reach scale morphology and discharge was evident in the fisheries populations with the Rivelin having similar observed densities of brown trout as the Loxley. Altering the compensation flow regimes appears to lead to an increase in the growth rate of older trout within the Rivelin.A two-dimensional hydraulic model was used to simulate the distributions of depths and velocities on four study reaches (two on the Rivelin; two on the Loxley). The model was calibrated to three separate calibration data sets. Subsequently, steady state simulations were conduced for the pre and post change compensation flows in each of the reaches. This output was subsequently linked to a fuzzy-logic based habitat model in order to generate predictions of available habitat. Predictions of available habitat were generated for four life stages of brown trout and for functional feeding groups of macroinvertebrates.
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Springer, T. M. "An assessment of the effects of with-flow bus lanes on service reliability." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371451.
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Karami, Gholam Hossein. "Assessment of heterogeneity and flow systems in karstic aquifers using pumping test data." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247880.
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Mandour, Eldeeb Mohamed F. "Development and Assessment of Altitude Adjustable Convergent Divergent Nozzles Using Passive Flow Control." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415283904.
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Zajac, Jakub. "Assessment of Ventricular Function in Normal and Failing Hearts Using 4D Flow CMR." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141006.
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Heart failure is a common disorder and a major cause of illness and death in the population, creating an enormous health-care burden. It is a complex condition, representing the end-point of many cardiovascular diseases. In general heart failure progresses slowly over time and once it is diagnosed it has a poor prognosis which is comparable with that of many types of cancer. The heart has an ability to adapt in response to long lasting increases in hemodynamic demand; the heart conforms its shape and size in order to maintain adequate cardiac output. This process is called remodeling and can be triggered by pathologies such as hypertension or valvular disease. When the myocardial remodeling is maintained chronically it becomes maladaptive and is associated with an increased risk of heart failure. In many cases, heart failure is associated with left bundle branch block (LBBB). This electrical disturbance leads to dyssynchronous left ventricular (LV) contraction and relaxation which may contribute to cardiac dysfunction and ultimately heart failure. Mechanical dyssynchrony can be treated with cardiac resynchronization therapy (CRT). However, many heart failure patients do not demonstrate clinical improvement despite CRT. Blood flow plays an important role in the normal development of the fetal heart. However, flow-induced forces may also induce changes in the heart cells that could lead to pathological remodeling in the adult heart. Until recently, measurement tools have been inadequate in describing the complex three-dimensional and time-varying characteristics of blood flow within the beating heart. 4D (3D + time) flow cardiovascular magnetic resonance (CMR) enables acquisition of three-dimensional, three-directional, time-resolved velocity data from which visualization and quantification of the blood flow patterns over a complete cardiac cycle can be performed. In this thesis, novel 4D Flow CMR based methods are used to study the intraventricular blood flow in healthy subjects and heart failure patients with and without ventricular dyssynchrony in order to gain new knowledge of the ventricular function. Different flow components were assessed in normal heart ventricles. It was found that inflowing blood that passes directly to outflow during the same heartbeat (the Direct Flow component) was larger and possessed more kinetic energy (KE) than other flow components. Diastolic flow through the normal heart appears to create favorable conditions for effective systolic ejection. This organized blood flow pattern within the normal LV is altered in heart failure patients and is associated with decreased preservation of KE which might be unfavorable for efficient LV ejection. Inefficient flow of blood through the heart may influence diastolic wall stress, and thus contribute to pathological myocardial remodeling. In dyssynchronous LVs of heart failure patients with LBBB, Direct Flow showed even more reduced preservation of KE compared to similarly remodeled LVs without LBBB. Furthermore, in LBBB patients, LV filling hemodynamic forces, acting on the myocardium, were more orthogonal to the main flow direction compared to patients without LBBB. Deviation of LV flow forces and reduction of KE preservation and may reflect impairment of LV diastolic function and less efficient ensuing ejection related to dyssynchrony in these failing ventricles. Blood flow patterns were also studied with respect to fluctuations of the velocity of the flow (turbulent flow) in normal and failing LVs. In failing hearts, turbulent kinetic energy (TKE) was higher during diastole than in healthy subjects. TKE is a cause of energy loss and can thus be seen as a measure of flow inefficiency. Elucidating the transit of multidimensional blood flow through the heart chambers is fundamental in understanding the physiology of the heart and to detect abnormalities in cardiac function. The 4D Flow CMR parameters presented in this thesis can be utilized to detect altered intracardiac blood flow and may be used as markers of deteriorating cardiac function, pathological remodeling and mechanical dyssynchrony in heart failure.
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Eliasson, Åse. "Groundwater impact assessment and protection." Licentiate thesis, KTH, Civil and Environmental Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1234.
Full textAbstract:
In the recent decades, therehave been frequent conflicts between groundwater waterresources and environmentally hazardous activities. Newmethodologies for aiding decision-making in groundwater impactassessment and protection areneeded and in which issues ofincreased awareness, better understanding of the groundwaterresources processes, and validation of predictive mathematicalmodels are addressed.
A framework fordecisionaid, based on predictive simulations that a)predicts the environmental impacts b) provides the totaleconomical value c) visualises the impacts and the groundwaterproperties and d) describes the uncertainties in the results isproposed herein. The framework can be applied in environmentalimpact assessments, strategic environmental assessments andprotection and management of water resources. The results ofthe model are used as feedback for determining new scenarios,depending on the required uncertainties, and if the plannedactivity is sustainable, and/or fulfils the legislative andpolicy measures. This framework is applied to a particular casestudy, Nybroåsen, in the south-eastern part of Sweden,where the highway E22 is constructed through the importantglaciofluvial esker aquifer, passing the protection zone of thewater supply for the Kalmar municipality.
The impacts from the new highwayand the existing road have been predicted by two-dimensionalphysically based time-variant flow and solute groundwatermodelling. The results, breakthrough curves of contaminantconcentration in wells and maps of concentration distributions,as well as travel times, flow paths, and capture zones forwells determined by particle tracking have been presented.
The constructed model of theNybroåsen study area was calibrated by comparing observedand simulated groundwater levels for 15 observation wells forten years of measurements. The model has been evaluated bothgraphically and numerically and the calibration target wasfulfilled for 13 of the 15 observation wells. The model workincludes investigations of the catchment information, a waterbalance study, simulation of the groundwater recharge,consideration of the unsaturated zone by a numerical columnsimulation, and sensitivity analysis.
From the sensitivity analysis ofthe flow and transport parameters, it has been shown that theuncertainties are mainly due to the hydraulic conductivity.Comparison of the derived conductivity from the steady-stateautomatic calibration and the time-variant calibration showedthat there are major differences in the derived parameters,which illustrates the importance of a time dependentcalibration over both wet and dry periods and in more than onepoint in the area of interest of the model predictions.
In addition, a multi-criteriadecision analysis has been carried out for four roadalternatives (including the new highway E22) and the existingroad in the case study concerned. The multi-criteria decisionaid is applied as an illustration of how it can be used in thestudy area to identify a) interest groups of actors and theirconcerns b) ranking of alternative road scenarios according toactorspreferences and c) coalition groups of actorsi.e.groups that have similar views with regard to theroad alternatives.
Keywords:Physically-based groundwater modelling,contamination, flow and solute transport, glaciofluvialdeposits, Nybroåsen, Sweden, and multi-criteriadecision-aid.
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James, Philippe Pierre. "A technique for the assessment of strength of coupling between statistical energy analysis subsystems." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245304.
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Paudel, Bhuwani Prasad. "GIS-based Assessment of Debris Flow Susceptibility and Hazard in Mountainous Regions of Nepal." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38817.
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Rainfall-induced landslides that change into debris flows and travel large distances are one of the treacherous natural calamities that can occur in mountainous areas, particularly in Nepal’s mountains. Debris flow was the second highest cause of human death in Nepal after epidemics between 1971 and 2016. Because debris flow is common in mountainous regions, its prediction and remedial measures through land use plans are important factors to consider for saving lives and properties. The spatial distribution of the initial landslides that change into debris flow, on a watershed scale, is still an important area of study in this mountainous region to develop essential land use plan.
In this research, hydrologic, slope stability and Flow-R models are applied in GIS modeling to locate potential landslide and debris flow areas for a given threshold rainfall in a mountainous watershed-Kulekhani, Nepal. Soil samples from 73 locations within the watershed and a geotechnical investigation on one old landslide area were considered to determine the Soil Water Characteristics Curve (SWCC), friction angle, cohesion, and infiltration characteristics of the subsurface soils in the study area. This information is applied in an unsaturated slope stability model to find unstable locations in the study watershed in a GIS environment. The model is tested on a recorded 24-hour rainfall of 540 mm in the watershed, and potential landslide locations are obtained. The validation results show that there is a good agreement between the predicted and mapped landslides. For debris flow run out, Flow-R model, which has the capability to analyze debris flow inundation with limited input information, and the model software is readily available in the public domain, was chosen for further analysis. Two recent debris flow events and the study watershed are taken as case studies to identify the appropriate algorithms of Flow-R for runout analysis of the study areas.
Landslide-triggering threshold rainfall frequency is related to the frequency of landslides and the debris flow hazard in these mountains. The above validated models are applied in a GIS environment to locate potential debris flow areas in expected threshold rainfall. Rainfall records from 1980 to 2013 are computed for one- to seven-day cumulative annual maximum rainfall. The probable rainfalls for 1 in 10 to 1 in 200 years return periods are identified. The anticipated probable rainfalls are modeled in the GIS environment to identify the factor of safety of mountain slopes for landslide susceptibility in the study watershed. The Flow-R model with user-defined landslide-susceptible areas was chosen for debris flow runout analysis. A relation between the frequency of rainfall and landslide-induced debris flow hazard area is derived for return periods of 25, 50, 100, and 200 years. Also, the debris flow hazard results from the analysis are compared with a known event in the watershed and found to agree. This developed method can be applied to anticipated landslide and landslide-induced debris flow from the live rainfall record to warn hazard-prone communities for saving lives and regulating hazardous transportation corridors in these mountains. In addition to this, this methodology will be a useful tool to help policy makers create appropriate land use plans.