Objetivos generales: - Investigar los aspectos vinculados a la obtención de servicios de streaming, el modelado de redes de datos y la caracterización del tráfico allí cursado. - Determinar un mecanismo que permita establecer un orden entre los nodos que brindan un determinado servicio o recurso deseado en una red "best effort" como es Internet Objetivos específicos: - Armar una taxonomía de los servicios que se pueden brindar en redes IP. - Analizar diferentes formas de modelizar redes de datos, de manera tal que resulte lo más fiel posible a la realidad de una red como Internet, en cuanto a topología, velocidad de enlaces, agregación y caracterización del tráfico, congestión, etc. - Diagramar y ejecutar simulaciones, en un modelo de red, que permitan cuantificar parámetros de comunicación (bandwidth, delay, jitter, packet loss) en diferentes tipos de servicios que se pueden brindar en dicha red. - Establecer un criterio que permita ordenar los nodos que ofrecen el servicio deseado considerando los resultados de las simulaciones abordadas.

The past decade has witnessed the fast development of peer-assisted video ondemand (PA-VoD) systems, which have attracted millions of online users. The efforts on improving the quality of video programs have never ceased since the beginning, and nowadays offering high-definition (HD) channels has become a common practice. However, compared with standard-definition (SD) channels, HD channels have to sustain a higher streaming rate to peers, which is a challenging task. In real systems, HD channels often suffer from poor streaming quality, or impose a heavy burden on the servers. This thesis conducts an in-depth study on peer cache and upload bandwidth management at the same time for multi-channel PA-VoD systems, where HD and SD channels coexist with different bandwidth and cache requirements. The objective is to minimize the server bandwidth consumption, and thus the maintenance cost of VoD service providers. The solution is cross-channel allocation (or view-upload decoupling), i.e., making SD channels help HD viewers with the surplus peer-contributed resources. The management of these resources includes bandwidth allocation and caching strategies. We first propose a generic modeling framework to capture the essential characteristics of PA-VoD systems: the demand and supply of bandwidth from peers. Our modeling framework can be customized or extended to model a variety of caching strategies, including FIFO, passive caching, and active caching with different user behaviors. We then apply the modeling framework to two representative scenarios: stationary scenarios, where the channels have fixed popularity; and non-stationary scenarios, in which a new movie is released, and peers enter the channel in a flash-crowd manner. We prove using our models that passive caching is efficient for stationary user behaviors, and derive the optimal caching solutions when the channels in the system demonstrate different popularity evolutions, i.e., with non-stationary behaviors. With the insights gained from our modeling work, we design effective centralized heuristic algorithms and practical distributed strategies for peer cache replacement and upload bandwidth allocation, with a near-optimal utilization of these resources. We propose centralized and distributed cross-channel allocation, and also extend the substreaming technique from live streaming to VoD systems, where it demonstrates its extreme feasibility. Our extensive simulation results verify the efficacy of these heuristic and practical strategies. / Graduate / 0984 / changlecsu@gmail.com

Τα τελευταία χρόνια είδαν την άνθιση διαδικτυακών εφαρμογών και υπηρεσιών διαμοιρασμού αντικειμένων πολυμέσων. Την τιμητική τους είχαν τα αντικείμενα οπτικοακουστικού περιεχομένου (video), δίνοντας πρωταγωνιστικό ρόλο στην ανάπτυξη συστημάτων διαμοιρασμού βίντεο. Μάλιστα, ανταποκρινόμενα στην δυνατότητα των χρηστών για επιλογή περιεχομένου, που παρείχαν η ραγδαία αύξηση της χρήσης του διαδικτύου και η βελτίωση των υποδομών αυτού, έγιναν ιδιαίτερα δημοφιλή τα συστήματα και οι υπηρεσίες διαμοιρασμού βίντεο κατόπιν ζήτησης Ωστόσο οι αυξημένες απαιτήσεις τους σε κλιμάκωση, προσαρμοστικότητα, απόδοση και ανεκτικότητα σε σφάλματα, κατέστησαν απαραίτητη την υποστήριξή τους από κατανεμημένες ή και παράλληλες αρχιτεκτονικές. Μία αρκετά υποσχόμενη προσέγγιση προς αυτή την κατεύθυνση είναι τα διομότιμα συστήματα καθώς οι ίδιοι οι χρήστες των εφαρμογών διαθέτουν ένα τεράστιο σύνολο από δικτυακούς και υπολογιστικούς πόρους. Στα συστήματα αυτά το περιεχόμενο που κατεβάζουν οι χρήστες διασπάται σε κομμάτια τα οποία ανταλλάσσονται από αυτούς ,με σκοπό την τελική επανασύνδεση και ανάκτηση του συνολικού μεγέθους των δεδομένων. Σκοπός αυτής της διπλωματικής είναι η μελέτη της αξιοποίησης του εύρους ζώνης στα πλαίσια ενός διομότιμου συστήματος διαμοιρασμού βίντεο κατόπιν ζήτησης με πολλαπλά κανάλια. Η παρατήρηση του τρόπου συμπεριφοράς των χρηστών και του συνολικού συστήματος ως προς τον πολύτιμο αυτό δικτυακό πόρο, μπορεί να αποτελέσει την βάση για την ανάπτυξη εφαρμογών με μεγαλύτερη αποδοτικότητα, πιο οικονομικών στην λειτουργία τους, και με βελτιωμένη ευελιξία. / The last year saw the flourishing of Internet applications and services sharing media objects. Their honor were the objects of audiovisual content (video), giving a leading role in the development of video sharing. Indeed, in response to users' ability to select content, provided by the rapid growth of internet usage and to improve the infrastructure of this, became very popular in the systems and services for sharing video on demand However, the increased demands on scalability, flexibility, performance and fault tolerance, made it necessary to support them or from distributed and parallel architectures. A very promising approach in this direction is the diomotima systems and the users themselves applications have a huge amount of network and computing resources. In these systems the content download users cleaved into pieces which are exchanged by them, with the final reconnection and recovery of the total size of data. The aim of this thesis is to study the utilization of bandwidth within a peer sharing system video on demand with multiple channels. The observation of how user behavior and the overall system to this valuable web resource, can provide the basis for developing applications with greater efficiency, more economical to operate, and with improved flexibility.

This diploma thesis presents a design of a wastewater treatment plant for a selected agricultural estate. Its literature research deals with technologies for wastewater treatment plants and relevant legislation. Furthermore, the characteristics of the agricultural estate are discussed in relation to the given area. The original state of wastewater treatment is presented and analysed both in terms of qualitative and quantitative agricultural data. Parameters of a new wastewater treatment plant and possible alternatives are designed and their advantages and disadvantages compared. Each of the possible solutions is then presented in the graphical part of the thesis.

This thesis deals with the evaluation of hydrochemical characteristics of groundwater (dripping water) in The Chýnov Cave and the subsequent statistical processing of the results. There were followed three sampling points, which were irregularly distributed in the cave system. Bicarbonates occured as the dominant anions in the dripping water. The dominant cation was calcium. Water can therefore be classified as bicarbonate - calcium. This corresponds with the expectations for The Chýnov cave location. There were also detected enhanced concentrations of nitrates and sulphates at sampling site Štola - this has long-term character and influences the quality of the underground stream of The Chýnov cave, which is directly connected to spring "Rutický" (source of drinking water for the town of Chýnov). Although a protective zone is declared over the whole territory of Rutice water resources, there is increased amount of nitrates and sulphates which probably has anthropogenic character and it comes from applied fertilizer and mineralization processes in arable land in the close surrounding of the National Natural Monument: The Chýnov cave.

No description available.

The Dissertation thesis compares the methods of hygienisation of wastewater treatment plants sludges with respect to meeting legislative requirements of conditions for using treated sludges on agricultural land. The thesis draws a comparison between the method of stabilisation and hygienisation of the sludge through the autothermal aerobic thermophilic stabilisation (AATS) by pure oxygen and the method of sludge hygienisation by pasteurization. The objective of the thesis is to evaluate the above-mentioned methods of hygienisation of wastewater treatment plant sludges, to compare their efficiency and a level of secondary contamination by indicator microorganisms before their subsequent treatment.

The topic of thesis deals with a hydrological model SWAT used for impact assessment of landscape structure on surface water pollution in Krivoklatsko protected area. For this purpose using ArcSWAT in the ArcGIS environment there were built hydrological models of three watersheds of various landscape structure located in the area of interest. The measured data of nitrate were used for these models. Concentration of nitrates in the surface waters were simulated by using these models in the period from 2003 until mid-2014. The statistical evaluation of the models including actual landscape structure did not show satisfactory match of the simulated values with the measured values. Due to the uncertainties of the model, including insufficient quantity of measured nitrates, it was not possible to expect exact results. After validation of basic models, it was important to create new models that would include various scenarios of landscape structure organization. New versions represented changes in the use of land classified as arable land in pasture or mixed forests, in the area around the stream to 250 m and 500 m. Modelling of the impact of individual scenarios on the structure of the landscape structure on nitrate concentrations there was displayed a positive effect of grassing and afforestation of...

Angl. resumé

In this thesis occurrence of emerging pollutants in different compartments of aquatic environment was studied. Different environmental matrices were covered: wastewater, surface water and fish tissues with the focus on pharmaceuticals, illicit drugs and perfluorinated compounds. Although numerous pharmaceuticals have been already detected in aquatic environment all over the world, still there is need for new reliable methods for their detection and quantification. The output of the study is three multi-residue methods for the analysis of pharmaceuticals and illicit drugs in water and fish samples. Their main advantage is that wide range of compounds from different classes is covered, which enables obtaining maximum information with minimum analytical effort. All the methods were validated including such key parameters as limits of quantification, selectivity, recovery and repeatability, and showed excellent performance allowing determination of target compounds at trace levels. Consequently, the methods were applied for the monitoring of POCs in different environmental samples. Wide occurrence of pharmaceuticals in Swedish WWTP effluents was shown. Rather high concentrations for the representatives of anti-hypertension drugs, some antibiotics and anti-depressants were detected. This fact stresses the importance of WWTP´ effluent monitoring as it is the main source of PPCPs in the aquatic environment. Passive sampling approach was tested for the monitoring of POCs in wastewater. Both standard configurations of POCIS were calibrated under the field conditions for a broad range of contaminants. Sampling rate values were calculated for the case of wastewater effluent. This is a significant contribution to the potential widespread application of POCIS for environmental monitoring programs. Analysis of biota samples is an essential part in the assessment of pollutants? fate in aquatic environment. Therefore, the screening of antibiotics in fish available at the Czech market was carried out. Thirty-two antibiotics from different classes were analyzed. The fish and shrimp samples were bought from the three biggest supermarkets in České Budějovice, which belong to a network of shops covering the whole Czech Republic. In total 97 samples were obtained. Found concentrations did not exceed MRL values established in the European Union. No antibiotics were detected in the fish of Czech origin. Still, presence of antibiotic residues in edible fish tissues could be a matter of concern and the sign of improper use of antibiotics in aquaculture industry, what consequently can cause adverse effects for the environment and human health.