Contractile floating barriers for confinement and recuperation of oil slicks

Marine oil spills can cause serious environmental damages to natural resources and to those whose sustenance depends upon these resources. Unfortunately experience shows that even the best efforts have not prevented occasional occurrences of major accidents on the sea. As long as massive oil spills are probable, special techniques and equipments will remain essential to facilitate spill cleanup in coastal regions. Oil spill containment booms are the most commonly adopted techniques to collect and contain oil on the sea surface, or to protect specific areas against slick spreading. Recently, an anti-pollution boom called the Cavalli system, has been designed with the intention of preventing the spread of spilled oil by trapping it inside a flexible floating reservoir and improving the pumping operation by decreasing the reservoir surface, and consequently increasing the oil layer thickness. Although flexible barriers have become increasingly common as a cleanup facility, there is no more than inadequate elaborate knowledge about their behavior. According to an extensive literature review, most of existing researches, either physical or numerical, have been done for rigid barriers. The main motivation for introducing the present research project is to study the efficiency and operational limits of the Cavalli system. However, the objectives are not constrained to this particular case. The present investigation focuses on the behavior of flexible barriers containing spilled oil. Previous researches of containment booms, even for the case of rigid barriers, have been mainly carried out in calm water. Accordingly, the main concentration is devoted to the response of a flexible barrier in presence of sea waves. Both experimental and numerical approaches were pursued to evaluate the efficiency limits and behavior of flexible barriers. Two-dimensional experiments have been carried out in a laboratory flume 6.5 m long, 1.2 m deep, and 12 cm wide. Flexible and rigid barriers containing rapeseed oil were examined, with and without waves. As the first step, the behavior of a flexible barrier in currents without waves was studied and compared to that of a rigid barrier. The key challenge was to contain the oil behind a flexible barrier that can freely deform in the water flow. This could be achieved using a slitted side skirt on the boom where it faces the lateral wall of the flume. The failure mode observed for rapeseed oil was entrainment failure. The initial failure velocity of different experimental conditions was studied and an empirical relationship was suggested in order to assess the maximum permissible oil-water relative velocity as a function of barrier draft and oil characteristics. The geometrical characteristics of the contained slick were examined and empirical equations were proposed to predict the slick length and headwave thickness as a function of contained oil volume. The second and more significant step was to conduct experiments with a flexible floating barrier in presence of five different waves. The analysis focused on the relationship between the failure velocity and the wave parameters with an emphasis on the behavior of flexible barriers. Likewise, empirical equations were proposed for the prediction of the initial failure velocity and geometrical characteristics of the slick. A type of drainage failure, namely, surging drainage was observed in the presence of waves. It was shown that the wave steepness and oil layer thickness are the dominant parameters in such failure. It was noticed that by decreasing the wave period or increasing the wave height, interfacial waves became more aggressive and consequently failure initiated at a lower velocity. Flexible barriers were more sensitive to the variations of wave characteristics. Applying appropriate time and length scales, a critical wave period of 6 s and wave height of 0.5 m were proposed for the prototype. Accurate measurements of velocity profiles and flow patterns in the vicinity of barriers with different conditions by means of Ultrasonic Velocimetry Profiling (UVP) and Large-Scale Particle Image Velocimetry (LSPIV) methods provided a reasonable understanding of the hydrodynamics in the vicinity of the barrier. The characteristics of the headwave at the upstream end of the oil slick were deliberately compared to those of a gravity current. It was concluded that despite geometrical similarities, these two phenomena are quite diverse. Furthermore, the oil-water interface was traced by detecting the maximum ultrasonic echo intensity, and velocity profiles in water and oil phases were independently obtained. To enhance the understanding of the mechanisms associated with oil containment failure, numerical simulations of multiphase flow were carried out using FLUENT code, applying the finite volume method (FVM). Comparisons between the obtained flow pattern and velocity field derived from numerical simulations and precise experimental measurements confirmed the capability of the numerical model to simulate the multiphase flow. The turbulence wake downstream of rigid and flexible barriers was simulated with and without the presence of oil phase. The simulations revealed the effect of contained oil on flow pattern and consequently the drag force acting on the barrier. Simulations of a full-scale barrier proposed a drag coefficient, Cd, of 1.90 for rigid barriers. Contrarily a constant value for the drag coefficient cannot be attributed to flexible barriers, since its deformations do not allow it to form similar shapes at different velocities. Last but not least, comparing the drag force on a rigid barrier with that of a flexible barrier towed by the same velocity demonstrated the fact that the forces acting on the skirt could be appreciably reduced by allowing flexibility

Physical and numerical modeling of harbors and shore protection measures / Modélisation physique et numérique de mesures de protection portuaires et d’aménagement de plages

The expansion project of the ‘’Port de la Nautique’’ and the creation of adjacent new beaches on the ‘’Lac Léman’’ in Geneva is currently under survey. In the conceptual and study phase, numerical- and physicalscaled models have been exploited at the Ecole Polytechnique Fédérale de Lausanne (EPFL). The objectives are to analyze the courantology and the wave’s field inside the protected zone of the harbor and their influence on the stability of the new beaches. The numerical modeling is driven by two models at different scales. The large scale model provides the boundary conditions to the small one which is used to estimate the circulation of water in the new harbor and to predict the erosion and deposition processes inside the harbor and along the beaches. The physical model is built using distorted scale factors inside an experimental wave tank that covers the same area as the small numerical model. It aims to optimize the project and to confirm the numerical results concerning notably the wave heights inside the harbor and the sediment transportation processes all along the beaches. The results obtained by the complicity of the numerical and physical simulations helped to converge toward an optimal design locations, orientations, and types of the protective dikes of the port as well as the geometric configuration and number of groins and the choice of the suitable backfill grain size for the new beaches

Velocity profiles and interface instability in a two-phase fluid: investigations using ultrasonic velocity profiler

In the present study the velocity profiles and the instability at the interface of a two phase water-oil fluid were investigated. The main aim of the research project was to investigate the instability mechanisms that can cause the failure of an oil spill barrier. Such mechanisms have been studied before for a vast variety of conditions. Although the velocity field in the region behind the barrier can influence the failure significantly, it had not been measured and analyzed precisely. In the present study the velocity profiles in the vicinity of different barriers were studied. To undertake the experiments, an oil layer was contained over the surface of flowing water by means of a barrier in a laboratory flume. The ultrasonic velocity profiler method was used to measure velocity profiles in each phase and to detect the oil–water interface. The effect of the barrier geometry on velocity profiles was studied. It was determined that the contained oil slick, although similar to a gravity current, can not be considered as a gravity current. The oil–water interface, derived from ultrasonic echo, was used to find the velocity profile in each fluid. Finally it was shown that the fluctuations at the rearward side of the oil slick head are due to Kelvin–Helmholtz instabilities

Expertise hydraulique d’un projet lacustre

Dans la phase d'étude de la création de plages et de l'agrandissement de l'adjacent Port de la Nautique sur le Léman à Genève, la complémentarité des modèles numérique et physique a permis de converger vers une solution optimale pour cet aménagement complexe

Untersuchung von Renaturierungskonzepten am Seeufer Gals, Bielersee

Analyse des ökologischen Aufwertungspotentials am Seeufer Gals (Bielersee, Schweiz), welche mithilfe einer hydrodynamisch- numerischen Modellierung mit der Software MIKE 21 und Bestimmung von Makrophyten vorgenommen wurde. Unter der Annahme von zwei unterschiedlich starken Windszenarien wurden die windinduzierten signifikanten Wellenhöhen und die welleninduzierten Strömungen für verschiedene Varianten simuliert. Die Ergebnisse der Modellierungen zeigten, ob die in den Varianten geplanten Massnahmen eine Reduzierung der Wellenhöhen und der Strömungen verursachen. Das Hauptziel war, Bedingungen zu schaffen, welche den Habitatsansprüchen von Makrophyten zusagen und somit eine Neuansiedlung von Makrophytenarten an dem Seeufer Gals möglich machen und gleichzeitig die Wellenbelastung auf das Ufer zu verringern, um eine fortschreitende Erosion zu vermeiden. Mithilfe einiger Massnahmen konnten erfolgsversprechende Ergebnisse erzielt werden, die zu einer Verbesserung der aktuellen Situation führen würden. Es wurde ebenfalls gezeigt, dass Makrophyten für die Beurteilung eine bedeutende Rolle spielen, doch eine Bewertung nur anhand von ihnen sehr schwierig ist, da sie nicht nur auf Wellen- und Strömungsbedingungen, sondern auf weitere Faktoren und zudem extrem schnell auf deren Veränderungen reagieren. Die Studie wurde im Rahmen einer Masterarbeit an der TU Dresden im Landschaftswerk Biel-Seeland durchgeführt

Strategic Model of Value Co-Creation of University with Emphasis on Fourth and Fifth Generation Universities

AbstractThe purpose of this article is to identify the factors, components and consequences of value co-creation of universities by emphasizing the fourth and fifth generation universities and consequently to present a conceptual model based on it. In order to conduct this research, in addition to in-depth study using the metasynthesis method to identify factors, components and consequences of value co-creation, fuzzy Delphi technique has been used to refine the factors and components. The survey was conducted in four stages and the results of each stage were refined using fuzzy Delphi method formulas. Finally, the strategic model of value co-creation of university with emphasis on value-creating and civilization-building universities with 16 factors, 23 components and 13 consequences, each designed in three categories and presented as a proposed model for value co-creation of university.IntroductionCreating and presenting common value with the cooperation of stakeholders, or co-creation of value, is a concept that has attracted the attention of many academics and universities.The dominant logic of services is the latest revolutionary achievement in the management of organizations and services. According to this logic, customers have a value in co-creation and in this process, they share their resources, especially their skills and knowledge with suppliers, and bring value-creating actions to the fore. In the meantime, the vaue co-creation process as a theme based on interaction and two-way communication between individuals is a key theme throughout the higher education network that plays an undeniable role in moving universities towards progress and overcoming the challenges ahead. This is achieved when higher education stakeholders consider moving towards value co-creation.The question now is what approaches and requirements can be used in the university and the higher education system to involve customers and stakeholders in the value co-creation process. It was informed of their needs and expectations in his own language, used their knowledge and ability to meet the needs and provide a new solution, and satisfied them with their direct cooperation in creating value, and benefiting from their ability and assistance, Did the university and the higher education system also benefit from the results and performance of this phenomenon? The answer to this question requires examining and identifying the process of dimensions and components of value co-creation in universities. In addition, despite the various researches that researchers have done on the importance of value co-creation, there are very limited studies on the development and application of value co-creation dimensions in the university and higher education system, and no comprehensive approach and model has been presented in this field. Since the creation of shared value with organizational stakeholders requires planning, careful implementation and control based on measures of dynamic capabilities to create academic value in the long run, and ultimately this leads to a move towards a value co-creating and civilization-building university. This concept is considered as a strategic concept. Therefore, designing a value creation model and elements of strategic value co-creation in the context of the value creation process can cover the above gaps and help to develop knowledge frontiers in the fields of strategic management knowledge, services and education, as well as value co-creation. Therefore, this study intends to study the subject of value co-creation, effective factors, dimensions and components and consequences of university value creation using meta-synthesis and fuzzy Delphi method and provide a suitable model for university value co-creation.Case studyState universities of Kerman province  Theoretical frameworkThis research seeks to identify the factors, dimensions and consequences of value co-creation of university and presents a new plan of value co-creation features with the approach of new generation universities and the results in implementing measures and reforms related to university development.It can be used and enables universities to use this model to self-assess and pathology of the current situation and accordingly to plan and improve activitiesMethodologyThe present study is an applied research and based on the research design and in terms of data collection, it is a descriptive (non-experimental) research and three methods have been used to collect information, documentary study, Delphi and survey and there is a trinity in the method. In this research, meta-synthesis method has been used for in-depth study of literature and identification of factors, components and consequences of value co-creation of university from research literature and fuzzy Delphi method has been used to refine these variables. The statistical population of the research is in the meta-synthesis section of all articles published in journals with research topics of value creation, and fourth and fifth generation universities indexed in 9 valid databases in the period 2007 to 2020, and for fuzzy delphi, University professors (experts) who were fully acquainted with theories of value creation and academics were used.Discussion and ResultsIn this study, by metasynthesis method and study of 66 sources, 33 factors affecting value co-creation, 85 components and 24 consequences with academic value co-creation perspective (142 cases in total) were identified, which finally 20 factors, 43 components and 24 consequences according to the value  co-creation of university was identified and combined by fuzzy Delphi method.Finally, by conducting 4 stages of fuzzy Delphi survey, 16 factors, 23 components and 13 consequences were selected for the university value co-creation model and a conceptual model was presented.ConclusionGiven the recent advances in human consciousness and knowledge and the consequent development and change in the approach of universities from knowledge-based and research-oriented universities to entrepreneurial, value-creating and civilization-building universities, it seems to provide a relatively comprehensive version of the model. The value co-creation of university can be responsible for achieving the goals of civilization and value creation, and in the meantime, the use of a native model largely fills the existing gaps. The model presented in this study is able to provide the basis for the development of value co-creation in the Iranian higher education system and enable them to extract comprehensive plans and measures of improvement while comprehensive pathology of value creation in the Iranian higher education system. Evaluate their position in the process of value creation of human resources of the university with the approach of the fourth and fifth generation universities

Comprehensive numerical simulations of sediment transport and flushing of a Peruvian reservoir

Numerical modeling of sediment transport in reservoirs, especially for sudden events such as flushing, is still a challenging research topic. In the present study, sediment transport and sediment flushing are simulated for a Peruvian reservoir. Situated in the Peruvian Andes, the watershed is affected by high erosion rates and the river carries high amounts of suspended sediment whose estimated annual volume is about 5 Million m3. This study aims to investigate the reservoir sedimentation using different numerical models. A one-dimensional (1D) sediment transport model, a horizontal two-dimensional (2D) hydraulic model and a vertical 2D model are used for this purpose. Annual sedimentation, full drawdown flushing, and sediment concentration in power intakes are particularly investigated

Post-revascularization Ejection Fraction Prediction for Patients Undergoing Percutaneous Coronary Intervention Based on Myocardial Perfusion SPECT Imaging Radiomics:a Preliminary Machine Learning Study

In this study, the ability of radiomics features extracted from myocardial perfusion imaging with SPECT (MPI-SPECT) was investigated for the prediction of ejection fraction (EF) post-percutaneous coronary intervention (PCI) treatment. A total of 52 patients who had undergone pre-PCI MPI-SPECT were enrolled in this study. After normalization of the images, features were extracted from the left ventricle, initially automatically segmented by k-means and active contour methods, and finally edited and approved by an expert radiologist. More than 1700 2D and 3D radiomics features were extracted from each patient’s scan. A cross-combination of three feature selections and seven classifier methods was implemented. Three classes of no or dis-improvement (class 1), improved EF from 0 to 5% (class 2), and improved EF over 5% (class 3) were predicted by using tenfold cross-validation. Lastly, the models were evaluated based on accuracy, AUC, sensitivity, specificity, precision, and F-score. Neighborhood component analysis (NCA) selected the most predictive feature signatures, including Gabor, first-order, and NGTDM features. Among the classifiers, the best performance was achieved by the fine KNN classifier, which yielded mean accuracy, AUC, sensitivity, specificity, precision, and F-score of 0.84, 0.83, 0.75, 0.87, 0.78, and 0.76, respectively, in 100 iterations of classification, within the 52 patients with 10-fold cross-validation. The MPI-SPECT-based radiomic features are well suited for predicting post-revascularization EF and therefore provide a helpful approach for deciding on the most appropriate treatment.</p

The antitumor efficiency of combined electrochemotherapy and single dose irradiation on a breast cancer tumor model

Background. The aim of this study was to investigate the antitumor effectiveness of electrochemotherapy with cisplatin combined with suboptimal radiotherapy doses. Tumor radiosensitization was evaluated on large invasive ductal carcinoma tumors in Balb/C mice. Materials and methods. Tumors of an average volume of 630 mm3 were treated with cisplatin, electric pulses, radiotherapy, electrochemotherapy, alone as well as in appropriate combinations. Tumors were irradiated with Cobalt-60 γ-rays at doses 3 Gy and 5 Gy in combination with electrochemotherapy using cisplatin. Controls included each of the treatments alone as well as the combination of the radiotherapy with electric pulses alone or with cisplatin alone. Antitumor effectiveness was evaluated by tumor growth delay, tumor-doubling time, inhibition ratio and the objective response rates. Results. As anticipated, electrochemotherapy was more effective than the treatment with cisplatin alone or the application of the electric pulses alone. When treatments were combined with tumor irradiation at either 3 or 5 Gy, the combination with electrochemotherapy was more effective: at 5 Gy, 2 animals out of 8 were in complete remission 100 days later. In general the higher 5 Gy dose of γ-radiation was more effective than the lower one of 3 Gy. Conclusions. The results of our study demonstrate that irradiation doses, 3 Gy or 5 Gy, increase the antitumor effectiveness of electrochemotherapy with cisplatin on invasive ductal carcinoma tumors. Good antitumor results were achieved in experimental tumors with a size comparable to clinical lesions, demonstrating that this three-modality combined treatment is useful for the treatment of large lesions even at sub-optimal radiotherapy doses