Experimentelle und numerische Modellierung der hydraulischen Stabilität von geotextilen Sandcontainern für Küstenschutzwerke

More versatile materials and innovative solutions are required for the design of new, cost effective shore protection structures as well as for the reinforcement of existing threatened coastal barriers, including dune reinforcement and scour protection. Geotextile Sand Containers (GSC) is a relatively low cost, soft and reversible solution for the above problem with a history of more than 50 years in hydraulic and marine applications. Nevertheless, GSC is still an emerging technology and no proper guidelines are available for the design of GSC-structures on a sound scientific base. This PhD study attempts to evaluate the effect of the most important engineering properties of GSCs on the hydraulic stability of GSC-structures and to develop new formulae for the hydraulic stability of crest GSCs of submerged/low-crested GSC-structures. First, the present knowledge related to the engineering properties of GSCs and their effects on the stability of GSC-structures and the existing hydraulic stability formulae for GSC-structures were critically reviewed. Second, four series of especially designed laboratory experiments, which allowed us to have an insight into the influence of the above mentioned properties on the stability of GSC-structures and also to obtain the required parameters for the numerical modelling of their stability were performed. Experimental investigations consisted of two types of laboratory experiments (drop tests and pullout tests), small scale wave flume tests (hydraulic stability tests) and hydraulic flume tests (permeability tests). Third, numerical modelling of GSC-structures was conducted using the weakly coupled RANS-VOF model and FEM-DEM models. Finally, combining both the experimental and numerical results, new stability curves and simple formulae were developed for the hydraulic stability of crest GSCs. This newly developed stability curves and stability formulae are expected to foster the applications of GSC structures for coastal protection.Vielseitige und innovative Lösungen für die Bemessung effektiver Küstenschutzbauwerke sowie Verstärkung existierender, bedrohter Küstenbarrieren werden benötigt. Dies beinhaltet auch Dünenverstärkungen und Kolkschutzmaßnahmen. Sandcontainer aus Geotextilien (GSC) sind eine günstige, flexible und reversible Lösung, die schon mehr als 50 Jahre im marinen und wasserbaulichen Bereich Anwendung findet. Trotzdem befinden sich GSCs immer noch in der Entwicklung und es sind bisher keine Richtlinien zur Bemessung von GSC-Bauwerken auf Grundlage wissenschaftlicher Erkenntnisse vorhanden. Die vorliegende Arbeit ist fokussiert auf die Evaluierung der Einflüsse der wichtigsten Eigenschaften auf die hydraulische Stabilität von GSC-Bauwerken sowie der Entwicklung eines neuen Ansatzes zur Vorhersage der hydraulischen Stabilität von Kronen-GSCs von Unterwasser- bzw. sehr niedrigen GSC- Bauwerken. Zunächst wurde der Wissensstand zu den betreffenden Eigenschaften von GSCs und ihrem Einfluss auf die Stabilität von GSC-Bauwerken und bestehende hydraulische Stabilitätsansätze kritisch bewertet. Anschließend wurden vier speziell entwickelte Experimente durchgeführt, welche Einblick in den Einfluss der oben genannten Eigenschaften auf GSC-Bauwerke gewährte und die Randbedingung für die numerische Modellierung der Stabilität festlegte. Unterschiedliche Arten von Experimenten wurden durchgeführt: zwei Laborexperimente (Fall- und Zugversuche), kleinmaßstäbliche Wellenkanalversuche (hydraulische Stabilität) und Versuche im Strömungskanal (Durchlässigkeit). Weiterhin wurden numerische Simulationen der GSC-Bauwerke mit Hilfe eines schwach gekoppelten RANS-VOF und FEM-DEM Modells durchgeführt. Zuletzt wurden die Ergebnisse der experimentellen und numerischen Untersuchungen zusammengeführt und neue Stabilitätskurven und einfache Berechnungsansätze für die hydraulische Stabilität von Kronen-GSCs entwickelt

ECONOMIC FEASIBILITY OF GROWING GURICIDIA UNDER COCONUTS AS AN ENERGY SOURCE FOR DEN ORO THERMAL POWER PLANTS; AN EX-ANTE APPRAISASL

Growth of the demand for electricity intimately follows the growth of theeconomy of Sri Lanka. Since the hydro resources. the major source of electricityare insufficient to meet the growing demand for electricity, alternative powersources have to be employed. Gliricidia proves to be a promising source ofbiomass energy. Firms generating dendro-thermal power express theirwillingness to establish dendro-thermal power plants at the Coconut ResearchInstitute of Sri Lanka on build-operate and transfer (BOT) basis, and to purchaseGliricidia dry wood delivered at the power plant at Rs. 1250/MT. This studyexamines whether the farmers can supply Gliricidia at the above price with areasonable margin for them. The break-even price of a MT of dry wood deliveredat the power plant located 10 km from the coconut estate was computedemploying discounted cash now method. This was Rs.977, implying a margin ofsome 28(10 for growers. The analysis further demonstrated that the break-evenprice was more sensiti ve to variations in wood yield than the variations intransporting distances. The ex-ante appraisal concludes that the raising ofGliricidia under coconuts as an energy source for dendro-therrnal power plants isan economically viable proposition. However, other socio-economic factorsinlluencing the adoption of new technologies may be worth investigating.

Staging of lung cancer in a tertiary care setting in Sri Lanka, using TNM 7th edition. A comparison against TNM6

<p>Abstract</p> <p>Background</p> <p>Lung cancer is a leading cause of cancer-related mortality in Sri Lanka and throughout the world. The latest staging system for lung cancer is the tumor node metastasis (TNM) 7^thedition in which there are major changes to the previous version. The objective of our study was to find out the implications of TNM7^thedition on lung cancer staging in a resource limited setting, and to compare it with the previous TNM 6^thedition.</p> <p>Methods</p> <p>Patients with histologically proven lung cancer consecutively presented to respiratory unit of Teaching Hospital Kandy, Sri Lanka were recruited to the study over a period of one year from April 2010 to March 2011. They were staged using CT, ultrasound scan of abdomen, bronchoscopy and CT spine and brain when necessary. Staging was done using TNM 7 as well as TNM6. Surgical or non-surgical treatment arms were decided on staging and the number of patients in each treatment arm was compared between the two staging systems.</p> <p>Results</p> <p>Out of 62 patients, thirty four patients (54%) had metastatic disease and 19 (30%) of them had pleural effusions (M1a), while 15 (24%) had distant metastasis (M1b). When compared to TNM6 there was no difference in the number of patients in T1 category, but the number in T2 was higher in TNM7 (25 Vs 20). Similarly the number in T3 group was higher in TNM7 (11 Vs 5) and the number in M category was doubled (34 Vs 17 [Chi-6.46, <it>p </it>= 0.011]) compared to TNM 6. The number of patients suitable for surgery were 17(27.5%) in TNM 7 and 18(29%) [Chi-0.02, <it>p </it>= 0.88] in TNM6.</p> <p>Conclusions</p> <p>This study shows that a significant proportion of patients were having advanced disease with distant metastasis on presentation. The number of patients falling to stage IV is significantly higher when staged with TNM7 but there was no significant difference in the number of patients undergoing surgery when TNM 7 was used compared to TNM6.</p

The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP

Predictors of the development of myocarditis or acute renal failure in patients with leptospirosis: An observational study

<p>Abstract</p> <p>Background</p> <p>Leptospirosis has a varied clinical presentation with complications like myocarditis and acute renal failure. There are many predictors of severity and mortality including clinical and laboratory parameters. Early detection and treatment can reduce complications. Therefore recognizing the early predictors of the complications of leptospirosis is important in patient management. This study was aimed at determining the clinical and laboratory predictors of myocarditis or acute renal failure.</p> <p>Methods</p> <p>This was a prospective descriptive study carried out in the Teaching Hospital, Kandy, from 1st July 2007 to 31st July 2008. Patients with clinical features compatible with leptospirosis case definition were confirmed using the Microscopic Agglutination Test (MAT). Clinical features and laboratory measures done on admission were recorded. Patients were observed for the development of acute renal failure or myocarditis. Chi-square statistics, Fisher's exact test and Mann-Whitney <it>U </it>test were used to compare patients with and without complications. A logistic regression model was used to select final predictor variables.</p> <p>Results</p> <p>Sixty two confirmed leptospirosis patients were included in the study. Seven patients (11.3%) developed acute renal failure and five (8.1%) developed myocarditis while three (4.8%) had both acute renal failure and myocarditis. Conjunctival suffusion - 40 (64.5%), muscle tenderness - 28 (45.1%), oliguria - 20 (32.2%), jaundice - 12 (19.3%), hepatomegaly - 10 (16.1%), arrhythmias (irregular radial pulse) - 8 (12.9%), chest pain - 6 (9.7%), bleeding - 5 (8.1%), and shortness of breath (SOB) 4 (6.4%) were the common clinical features present among the patients. Out of these, only oliguria {odds ratio (OR) = 4.14 and 95% confidence interval (CI) 1.003-17.261}, jaundice (OR = 5.13 and 95% CI 1.149-28.003), and arrhythmias (OR = 5.774 and 95% CI 1.001-34.692), were predictors of myocarditis or acute renal failure and none of the laboratory measures could predict the two complications.</p> <p>Conclusions</p> <p>This study shows that out of clinical and laboratory variables, only oliguria, jaundice and arrhythmia are strong predictors of development of acute renal failure or myocarditis in patients with leptospirosis presented to Teaching Hospital of Kandy, Sri Lanka.</p

Crystal structures and freezing of dipolar fluids

We investigate the crystal structure of classical systems of spherical particles with an embedded point dipole at T=0. The ferroelectric ground state energy is calculated using generalizations of the Ewald summation technique. Due to the reduced symmetry compared to the nonpolar case the crystals are never strictly cubic. For the Stockmayer (i.e., Lennard-Jones plus dipolar) interaction three phases are found upon increasing the dipole moment: hexagonal, body-centered orthorhombic, and body-centered tetragonal. An even richer phase diagram arises for dipolar soft spheres with a purely repulsive inverse power law potential $\sim r^{-n}$. A crossover between qualitatively different sequences of phases occurs near the exponent $n=12$. The results are applicable to electro- and magnetorheological fluids. In addition to the exact ground state analysis we study freezing of the Stockmayer fluid by density-functional theory.Comment: submitted to Phys. Rev.

Effects of Deliberate Ingestion of Organophosphate or Paraquat on Brain Stem Auditory-Evoked Potentials

Organophosphate (OP) and paraquat (PQ) ingestion is a serious health problem. A common pathology behind OP or PQ poisoning is the generation of reactive oxygen species (ROS) which is known to cause ototoxicity. The aim of the study was to identify the effects of deliberate ingestion of OP or PQ on brain stem auditory-evoked potentials (BAEPs). Consecutive patients with deliberate self-poisoning with OP or PQ who were admitted to a secondary and a tertiary care hospital in the Southern province of Sri Lanka and matched controls were recruited. BAEPs were performed at 1 week (first assessment) and 6 weeks (second assessment) after the exposure. Interpeak latencies of I–III, III–V, and I–V were measured. There were 70 and 28 patients in the OP and PQ arms with the mean age of 32 ± 12 and 29 ± 12 years, respectively. There were 70 controls and their mean age was 33 ± 12 years. In OP and PQ poisoning, 53/70 and 18/28 came for the second assessment, respectively. The interpeak latency was not statistically different in the controls vs the first assessment, controls vs the second assessment, and the first vs the second assessment. There were no significant lesions in the auditory pathway in OP or PQ poisoned patients. The generation of ROS within the perilymphatic space following the ingestion of OP or PQ may not be sufficient to cause lesions in the auditory pathway. Further studies with the assessment of auditory threshold are needed

Dynamic polarizability of rotating particles in electrorheological fluids

A rotating particle in electrorheological (ER) fluid leads to a displacement of its polarization charges on the surface which relax towards the external applied field ${\bf E}_0$, resulting in a steady-state polarization at an angle with respect to ${\bf E}_0$. This dynamic effect has shown to affect the ER fluids properties dramatically. In this paper, we develop a dynamic effective medium theory (EMT) for a system containing rotating particles of finite volume fraction. This is a generalization of established EMT to account for the interactions between many rotating particles. While the theory is valid for three dimensions, the results in a special two dimensional configuration show that the system exhibits an off-diagonal polarization response, in addition to a diagonal polarization response, which resembles the classic Hall effect. The diagonal response monotonically decreases with an increasing rotational speed, whereas the off-diagonal response exhibits a maximum at a reduced rotational angular velocity $\omega_0$ comparing to the case of isolated rotating particles. This implies a way of measurement on the interacting relaxation time. The dependencies of the diagonal and off-diagonal responses on various factors, such as $\omega_0$, the volume fraction, and the dielectric contrast, are discussed.Comment: 6 pages, 4 figures, accepted to J. Phys. Chem.

New method to characterize a machining system: application in turning

Many studies simulates the machining process by using a single degree of freedom spring-mass sytem to model the tool stiffness, or the workpiece stiffness, or the unit tool-workpiece stiffness in modelings 2D. Others impose the tool action, or use more or less complex modelings of the efforts applied by the tool taking account the tool geometry. Thus, all these models remain two-dimensional or sometimes partially three-dimensional. This paper aims at developing an experimental method allowing to determine accurately the real three-dimensional behaviour of a machining system (machine tool, cutting tool, tool-holder and associated system of force metrology six-component dynamometer). In the work-space model of machining, a new experimental procedure is implemented to determine the machining system elastic behaviour. An experimental study of machining system is presented. We propose a machining system static characterization. A decomposition in two distinct blocks of the system "Workpiece-Tool-Machine" is realized. The block Tool and the block Workpiece are studied and characterized separately by matrix stiffness and displacement (three translations and three rotations). The Castigliano's theory allows us to calculate the total stiffness matrix and the total displacement matrix. A stiffness center point and a plan of tool tip static displacement are presented in agreement with the turning machining dynamic model and especially during the self induced vibration. These results are necessary to have a good three-dimensional machining system dynamic characterization