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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Naturalismo e naturalismos na pintura portuguesa do séc. XX e a Sociedade Nacional de Belas-Artes

Tavares, Cristina Azevedo, 1956- January 1999 (has links)
No description available.
22

Evolutionary optimisation for Volt-VAR power quality control

Boyi Bukata, Bala January 2013 (has links)
With the more environmentally friendly smart grid initiatives during the past few years, intelligent operation and optimisation of the electricity distribution system have received an increasing attention in power system research worldwide. Power flow from the distribution substation to the customer can be optimised at Volt-Ampere-Reactive (VAR) level by reducing the reactive power. Distributed Generation (DG) and Renewable Energy Sources (RES) represent both the broadest potentials and the broadest challenges for intelligent distribution systems and smart grid control. In general, the flexibility envisaged by integrating RES during smart grid transformation is often surrounded by nonlinearities such as wave-form deformations caused by harmonic currents or voltages, which impliedly increase control system complexity. Therefore, conventional controllers presently implemented need to be re-engineered in order to solve power quality (PQ) problems therein. This work aims to improve the controllability of Distribution Static Compensators (DSTATCOMs) through the development of improved control systems using evolu- tionary computation enabled design automation and optimisation. The resultant Volt-VAR Control (VVC) optimises PQ in the presence of nonlinearities and uncertainties. It also aims at increasing overall system’s sensitivity to unconsidered parameters in the design stage like measurement noise, unmodelled dynamics and disturbances. This is otherwise known as the robustness of the system offering it with valuable potential for future smart grids control, which are anticipated to present more nonlinearities due to virtual power plant (VPP) configuration. According to European Project FENIX, a Virtual Power Plant (VPP) aggregates the capacity of many diverse Distributed Energy Resources (DER), it creates a single operating profile from a composite of the parameters characterizing each DER and can incorporate the impact of the network on aggregate DER output. To particularly solve PQ problems, two objectives are realised in this thesis. First, a non-deterministic evolutionary algorithm (EA) is adopted to generate optimum fuzzy logic controllers for DSTATCOMs. This design methodology extends the traditional computer-aided-design (CAD) to computer-automated-design (CAutoD), which provides a unified solution to diverse PQ problems automatically and efficiently. While realizing this objective, the prediction ability of the derivative term in a proportional and derivative (PD) controller is improved by placing a rerouted derivative filter in the feedback path to tame ensuing oscillations. This method is then replicated in a fuzzy PD scheme and is automated through the capability of a “generational” tuning using evolutionary algorithm. Fuzzy logic controllers (FLCs) are rule-based systems which are designed around a fuzzy rule base (RB) related through an inference engine by means of fuzzy implication and compositional procedures. RBs are normally formulated in linguistic terms, in the form of if ... then rules which can be driven through various techniques. Fundamentally, the correct choice of the membership functions of the linguistic set defines the performance of an FLC. In this context, a three rule-base fuzzy mapping using Macvicar-Whelan matrix has been incorporated in this scheme to reduce the computational cost, and to avoid firing of redundant rules. The EA-Fuzzy strategy is proven to overcome the limitation of conventional optimisation which may be trapped in local minima, as the optimisation problem is often multi-modal. The second objective of the thesis is the development of a novel advanced model-free predictive control (MFPC) system for DSTATCOMs through a deterministic non-gradient algorithm. The new method uses its “look-ahead” feature to predict and propose solutions to anticipated power quality problems before they occur. A describing function augmented DSTATCOM regime is so arranged in a closed-loop fashion to locate limit cycles for settling the systems nonlinearities in a model-free zone. Predictive control is performed upon the online generated input-output data-set through the power of a non-gradient simplex algorithm. The strategy is to boycott the usage of a system model which is often based on gradient information and may thus be trapped in a local optimum or hindered by noisy data. As a model-free technique, the resultant system offers the advantage of reduction in system modelling or identification, which is often inaccurate, and also in computational load, since it operates directly on raw data from a direct online procession while at the same time dealing with a partially known system normally encountered in a practical industrial problem. Steady-state and dynamic simulations of both control and simulation models in Matlab/Simulink environment demonstrate the superiority of the new model-free approach over the traditional trial-and-error based methods. The method has been varified to offer faster response speed and shorter settling time at zero overshoot when compared to existing methods. A SimPowerSystems software simulation model is also developed to check experimental validity of the designs. Where specific PQ problems such as harmonics distortion, voltage swells, voltage sags and flicker are solved. A noticeable record level of THD reduction to 0.04% and 0.05% has respectively been achieved. It is therefore safe to recommend to the industry the implementation of this model-free predictive control scheme at the distribution level. As the distribution system metamorphoses into decen- tralised smart grid featuring connectivity of virtual power plants mostly through power electronic converters, e.g., DSTATCOM, it stands to benefit from the full Volt-VAR automated controllability of the MFPCs low control rate. Based on CAutoD, the practical implementation of this technique is made possible through digital prototyping within the real-time workshop to automatically generate C or C++ codes from Simulink, which executes continuous and discrete time models directly on a vast range of computer applications. Its overall wired closed-loop structure with the DSTATCOM would offer reliable and competitive advantages over its PID and SVC (CAD-based) counterparts currently being implemented through physical prototyping, in terms of; quick product-to-market pace, reduced hardwire size, small footprint, maintenance free as it is model-free (and automated), where pickling the controller timers and model contingencies are unnecessary as would be with the conventional controllers. More importantly, the scheme performs the aforementioned control functions robustly at a high speed in the range of 0.005 → 0.01 seconds. High enough to capture and deal with any ensuing PQ problem emanating from changes in customer’s load and system disturbances in an environmentally friendly, but less grid-friendly renewable generators.
23

External Control Of Puma 700 Series Robot Based On The Communication Protocols Lun And Ddcmp

Gebizlioglu, Onder Emin 01 December 2003 (has links) (PDF)
This thesis analyzes the supervisory control of the PUMA 700 series robot through a remote computer. Supervisory communication carries the control through MARK II controller, common controller for the PUMA robots, to a standard PC, enabling the development of purpose specific control programming without the knowledge of the VAL (Variable Assembly Language), robot-programming language. Using the supervisory communication feature of PUMA, new control software has been developed in which both VAL commands and interactive control commands can be executed simultaneously. The supervisory communication with the control software enables exploitation of third party applications and additional operating system features. The supervisory communication uses the Digital Data Communications Message Protocol (DDCMP). The frame structure of data messages, which is specific to PUMA robots, is fitted into this protocol. The messages embedded into DCMP are actually logical units, having different abilities and features. Data messages are formed with the interactive control software according to execution requests of the user. This thesis explains the implementation of the communication without using the CRC (Cyclic Redundancy Checking) on the remote computer side and the data messages formed with the interactive control software, which also enables the use of sensory inputs (camera, infrared, sound, color information) to be used for the robot motion control.
24

Deriving Strategies And Developing Balanced Scorecard For General Directorate Of Environmental Impact Assessment And Planning In Ministry Of Environment And Forestry.

Ozcan, Mehmet 01 December 2003 (has links) (PDF)
In this study, it is aimed to derive strategies and develop a Balanced Scorecard in General Directorate of Environmental Impact Assessment and Planning in Ministry of Environment and Forestry. Firstly, the objectives of the General Directorate defined in the law are reassessed and strategies to realize the objectives are derived by making use of feedback received by conducting surveys to 4 main stakeholder groups which are the staff of the General Directorate, Provincial Directorates, companies preparing EIA reports, other public institutions, and interviews with managers. Following the determination of strategies, performance measures for each strategy are specified, replaced into internal business perspective, stakeholder perspective and learning and growth perspective in the Balanced Scorecard and and finally deployed to head of departments and branch offices.
25

A New Route To The Synthesis Of Nanocomposites By Using An Unsaturated Polyester Matrix

Toprak, Pelin 01 September 2004 (has links) (PDF)
This study was conducted to investigate the effects of organoclay type and concentration on the nanocomposites synthesized by &ldquo / In-Situ Polymerization&rdquo / and &ldquo / Prepolymerization&rdquo / methods. In-Situ Polymerization Method was in fact a new route which consisted of dispersing the monomers / propylene glycol, maleic anhydride and o-phthalic anhydride into the galleries of montmorillonite followed by subsequent polymerization. The Prepolymerization Method involved the addition of montmorillonite to the previously synthesized unsaturated polyester. As the first step, all the compositions were prepared by Cloisite 30B, and then for comparison of clay type, nanocomposites containing 3 wt.% of Cloisite 15A and Cloisite 25A were also synthesized. The efficiency of the two methods were compared with regards to their structural, thermal and mechanical properties. According to the results of XRD analysis, in both methods, maximum intercalation was observed when Cloisite 30B was used. An exfoliated structure was obtained in the Prepolymerization Method at 3 wt. % Cloisite 30B content. In all clay types, the increase in the d-spacings of the organoclays was higher when the Prepolymerization Method was applied. With Cloisite 30B, maximum improvement in the impact strength was obtained at 3 wt. % organoclay loading and the In-Situ Method yielded better results leading to a 77% increase in the impact strength at this organoclay loading. Among the organoclay types, Cloisite 15A was found to give rise to maximum increase in the impact strength. With the Prepolymerization Method higher improvement in flexural strength and flexural modulus was obtained owing to the lower styrene content in the crosslinking medium. The elongation at break values followed a decreasing trend with increasing clay content but did not show any significant difference when the clay types were compared.
26

Characterization Of Kizilcahamam Geothermal Field By Tracer Testing

Kaya, Tevfik 01 September 2005 (has links) (PDF)
ABSTRACT CHARACTERIZATION OF KIZILCAHAMAM GEOTHERMAL FIELD BY TRACER TESTING Tevfik Kaya M.S, Petroleum and Natural Gas Engineering Department Supervisor : Assoc. Prof. Dr. Serhat Akin Co-Supervisor : Prof. Dr. Mahmut Parlaktuna September 2005, 107 Pages Kizilcahamam Geothermal Field which is 70 km far from Ankara, has been utilized for Geothermal District Heating System, 25 MWt, 2500 residences capacity, greenhouses heating, thermal facilities since 1994. The average production rate is 350m3/h during the heating season , 150m3/h during the summer season for hot water and yearly average reinjection rate is 114m3/h from the field. The long term projections has been studied concerning on expected pressure decline by matching 10 years field history data which contain dynamic level and temperature data. The pressure decline is 140 kPa in the field between 1999 and 2005 with the existing reinjection rate, if the existing rates do not change, the additional pressure decline which is 120 kPa will be occurred up to 2011. In order to get more information from the field, the fluorescein as tracer has been injected in to the MTA-1, and the samples were collected from the MTA-2, Fethi Bey, IHL-1 and IHL-3 for 3 months. The fluorescein concentration has been detected by using fluorimeter, and tracer concentration time plots were analyzed. The fluoreiscein was detected in short breakthrough time in MTA-2 and Fethi Bey which are close to reinjection well, breakthrough time is longer in IHL-1 and IHL-3. The interpretation of tracer test shows that there is communication between all wells. Tracer concentration time plots were compared with different mathematical models, the best match was obtained with multi-fractured model. These results show that Kizilcahamam field is not homogeneous field. It is expected that increasing the reinjection rate will decrease the pressure decline in the field.
27

A cultura popular como factor de desenvolvimento local-um olhar a partir da música

Neves, José António de Matos Esteves das, 1959- January 2000 (has links)
No description available.
28

Language, discourse and ideology : the Real Academia Española and the standardisation of Spanish

Paffey, Darren J. January 2008 (has links)
This thesis aims to investigate the nature of ideologies of language, and specifically to understand what kinds of linguistic, social, political and historical factors impact upon and inform ideologies of standardisation. I consider the particular case of the Spanish language, and examine how public debates in Spain’s press constitute discursive sites in which the ideologies of language authorities are evidenced. There are few studies which identify and critique the social actors in Spanish standardisation, and this thesis is a contribution to addressing that absence. By adopting a Critical Discourse Analysis approach , I seek to relate the microstructures of texts from two of Spain’s best-selling daily newspapers (El País and ABC) to the socio-political macrostructures in which press discourse is produced, and in which hegemonic ideologies underpin debates about Spanish. The press is a crucial vehicle of transmission in which language ideologies are staked out, and the large data corpus allows me to identify recurring aspects of discourse which become ‘naturalised’ and form ‘common sense’ beliefs about Spanish, its role, its authorities, and the practices of those who ‘guard’ the language. The principal guardian of Spanish, the Real Academia Española (RAE), is the particular focus of this thesis. I interrogate RAE discourse and shed light on this institution’s role in producing and maintaining a ‘standard’ Spanish in the contemporary context. Discourses of language unity and community are central, as are themes which form a vision of Spanish on an international scale. I argue that the RAE’s discourse serves to reinforce its authority and leadership in standardisation. I further argue that this centralisation of linguistic authority is occurring simultaneously with a rescaling and expansion of standardisation practices which go beyond the nation-state paradigm in pursuit of a ‘total Spanish’ guided by ‘panhispanic norms’. The role of other elite institutions in the panhispanic language policy is also legitimised in press discourse, with important social, cultural and commercial implications for not just Spain, but the entire Spanish-speaking world.
29

A Study Of Argumentation In Turkish Within A Bayesian Reasoning Framework: Arguments From Ignorance

Karaaslan, Hatice 01 September 2012 (has links) (PDF)
In this dissertation, a normative prescriptive paradigm, namely a Bayesian theory of content-dependent argument strength, was employed in order to investigate argumentation, specifically the classic fallacy of the &ldquo / argument from ignorance&rdquo / or &ldquo / argumentum ad ignorantiam&rdquo / . The study was carried out in Turkish with Turkish participants. In the Bayesian framework, argument strength is determined by the interactions between three major factors: prior belief, polarity, and evidence reliability. In addition, topic effects are considered. Three experiments were conducted. The first experiment replicated Hahn et al.&rsquo / s (2005) study in Turkish to investigate whether similar results would be obtained in a different linguistic and cultural community. We found significant main effects of three of the manipulated factors in Oaksford and Hahn (2004) and Hahn et al. (2005): prior belief, reliability and topic. With respect to the Bayesian analysis, the overall fit between the data and the model was very good. The second experiment tested the hypothesis that argument acceptance would not vary across different intelligence levels. There was no significant main effect of prior belief, polarity, topic, and intelligence. We found a main effect of reliability only. However, further analyses on significant interactions showed that more intelligent subjects were less inclined to accept negative polarity items. Finally, the third experiment investigated the hypothesis that argument acceptance would vary depending on the presence of and the kind of evidentiality markers prevalent in Turkish, indicating the certainty with which events in the past have happened, marked with overt morpho-syntactic markers (&ndash / DI or &ndash / mIs). The experiment found a significant main effect of evidentiality as well as replicating the significant main effects of the two of the manipulated factors (prior belief and reliability) in Oaksford and Hahn (2004), Hahn et al. (2005) and in our first experiment. Furthermore, reliability and evidentiality interacted, indicating separate as well as combined effects of the two. With respect to the Bayesian analysis, the overall fit between the data and the model was lower than the one in the first experiment, but still acceptable. Overall, this study supported the normative Bayesian approach to studying argumentation in an interdisciplinary perspective, combining computation, psychology, linguistics, and philosophy.
30

One Historian Two Books: Beatriz Colomina

Karamanoglu, Sema 01 January 2013 (has links) (PDF)
This thesis aims to explore selected works of Beatriz Colomina, a revisionist architectural historian who has made influential studies on visuality, domesticity, media and gender, and their reflections in the architectural world. Colomina is a distinguished architectural historian since she places a new lens on a period when architecture ceased to be only for the elite and media has gradually penetrated into everyone&rsquo / s life in order to understand how architecture became accessible to the public through media and how this has affected the perception of modern architecture. This new lens entailed not only the inseparability of media and architecture but also how war and domesticity featured in this relationship. Against this background, this study attempts to investigate the innovative approach of Beatriz Colomina by comparing and contrasting her two prominent books: Privacy and Publicity: Modern Architecture as Mass Media (1994) and Domesticity at War (2007). The former introduces us to the relationship between architecture and media, whereas the latter exemplifies this relationship by focusing on the cold war period as a time where media became an integral part of the domestic environment. This study aims to extract Colomina&rsquo / s contribution to architectural history by first disentangling and analysing and then merging these two books under common themes. In doing so, it seeks to answer the following questions: What is the role of archives in Colomina&rsquo / s methodology in writing these two books? What is the relationship between the document and the historian that emerges from this methodology? What common themes can be extracted from these two books as an analytical framework in order to better understand and study Colomina&rsquo / s approach? What differentiates her as a historian from other historians of modern architecture, specifically from Siegfried Giedion and Kenneth Frampton? What messages does Colomina give her reader through the form as well as the content of her books? What is her contribution to architectural historiography?

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