FPGA-based object detection using classification circuits

Dans l'apprentissage machine, la classification est le processus d’assigner une nouvelle observation à une certaine catégorie. Les classifieurs qui mettent en œuvre des algorithmes de classification ont été largement étudié au cours des dernières décennies. Les classifieurs traditionnels sont basés sur des algorithmes tels que le SVM et les réseaux de neurones, et sont généralement exécutés par des logiciels sur CPUs qui fait que le système souffre d’un manque de performance et d’une forte consommation d'énergie. Bien que les GPUs puissent être utilisés pour accélérer le calcul de certains classifieurs, leur grande consommation de puissance empêche la technologie d'être mise en œuvre sur des appareils portables tels que les systèmes embarqués. Pour rendre le système de classification plus léger, les classifieurs devraient être capable de fonctionner sur un système matériel plus compact au lieu d'un groupe de CPUs ou GPUs, et les classifieurs eux-mêmes devraient être optimisés pour ce matériel. Dans ce mémoire, nous explorons la mise en œuvre d'un classifieur novateur sur une plate-forme matérielle à base de FPGA. Le classifieur, conçu par Alain Tapp (Université de Montréal), est basé sur une grande quantité de tables de recherche qui forment des circuits arborescents qui effectuent les tâches de classification. Le FPGA semble être un élément fait sur mesure pour mettre en œuvre ce classifieur avec ses riches ressources de tables de recherche et l'architecture à parallélisme élevé. Notre travail montre que les FPGAs peuvent implémenter plusieurs classifieurs et faire les classification sur des images haute définition à une vitesse très élevée.

An Approach Towards The Development Of An Efficient Symmetric Key Encryption Scheme

n the recent years protection of information in digital form is becoming more important. Image and video encryption has applications in various fields including Internet communications, multimedia systems, medical imaging, Tele-medicine and military communications. During storage as well as in transmission, the multimedia information is being exposed to unauthorized entities unless otherwise adequate security measures are built around the information system. There are many kinds of security threats during the transmission of vital classified information through insecure communication channels. Various encryption schemes are available today to deal with information security issues. Data encryption is widely used to protect sensitive data against the security threat in the form of “attack on confidentiality”. Secure transmission of information through insecure communication channels also requires encryption at the sending side and decryption at the receiving side. Encryption of large text message and image takes time before they can be transmitted, causing considerable delay in successive transmission of information in real-time. In order to minimize the latency, efficient encryption algorithms are needed. An encryption procedure with adequate security and high throughput is sought in multimedia encryption applications. Traditional symmetric key block ciphers like Data Encryption Standard (DES), Advanced Encryption Standard (AES) and Escrowed Encryption Standard (EES) are not efficient when the data size is large. With the availability of fast computing tools and communication networks at relatively lower costs today, these encryption standards appear to be not as fast as one would like. High throughput encryption and decryption are becoming increasingly important in the area of high-speed networking. Fast encryption algorithms are needed in these days for high-speed secure communication of multimedia data. It has been shown that public key algorithms are not a substitute for symmetric-key algorithms. Public key algorithms are slow, whereas symmetric key algorithms generally run much faster. Also, public key systems are vulnerable to chosen plaintext attack. In this research work, a fast symmetric key encryption scheme, entitled “Matrix Array Symmetric Key (MASK) encryption” based on matrix and array manipulations has been conceived and developed. Fast conversion has been achieved with the use of matrix table look-up substitution, array based transposition and circular shift operations that are performed in the algorithm. MASK encryption is a new concept in symmetric key cryptography. It employs matrix and array manipulation technique using secret information and data values. It is a block cipher operated on plain text message (or image) blocks of 128 bits using a secret key of size 128 bits producing cipher text message (or cipher image) blocks of the same size. This cipher has two advantages over traditional ciphers. First, the encryption and decryption procedures are much simpler, and consequently, much faster. Second, the key avalanche effect produced in the ciphertext output is better than that of AES.

Models and methods for power monolithic microwave integrated circuits

Computer aided design of Monolithic Microwave Integrated Circuits (MMICs) depends critically on active device models that are accurate, computationally efficient, and easily extracted from measurements or device simulators. Empirical models of active electron devices, which are based on actual device measurements, do not provide a detailed description of the electron device physics. However they are numerically efficient and quite accurate. These characteristics make them very suitable for MMIC design in the framework of commercially available CAD tools. In the empirical model formulation it is very important to separate linear memory effects (parasitic effects) from the nonlinear effects (intrinsic effects). Thus an empirical active device model is generally described by an extrinsic linear part which accounts for the parasitic passive structures connecting the nonlinear intrinsic electron device to the external world. An important task circuit designers deal with is evaluating the ultimate potential of a device for specific applications. In fact once the technology has been selected, the designer would choose the best device for the particular application and the best device for the different blocks composing the overall MMIC. Thus in order to accurately reproducing the behaviour of different-in-size devices, good scalability properties of the model are necessarily required. Another important aspect of empirical modelling of electron devices is the mathematical (or equivalent circuit) description of the nonlinearities inherently associated with the intrinsic device. Once the model has been defined, the proper measurements for the characterization of the device are performed in order to identify the model. Hence, the correct measurement of the device nonlinear characteristics (in the device characterization phase) and their reconstruction (in the identification or even simulation phase) are two of the more important aspects of empirical modelling. This thesis presents an original contribution to nonlinear electron device empirical modelling treating the issues of model scalability and reconstruction of the device nonlinear characteristics. The scalability of an empirical model strictly depends on the scalability of the linear extrinsic parasitic network, which should possibly maintain the link between technological process parameters and the corresponding device electrical response. Since lumped parasitic networks, together with simple linear scaling rules, cannot provide accurate scalable models, either complicate technology-dependent scaling rules or computationally inefficient distributed models are available in literature. This thesis shows how the above mentioned problems can be avoided through the use of commercially available electromagnetic (EM) simulators. They enable the actual device geometry and material stratification, as well as losses in the dielectrics and electrodes, to be taken into account for any given device structure and size, providing an accurate description of the parasitic effects which occur in the device passive structure. It is shown how the electron device behaviour can be described as an equivalent two-port intrinsic nonlinear block connected to a linear distributed four-port passive parasitic network, which is identified by means of the EM simulation of the device layout, allowing for better frequency extrapolation and scalability properties than conventional empirical models. Concerning the issue of the reconstruction of the nonlinear electron device characteristics, a data approximation algorithm has been developed for the exploitation in the framework of empirical table look-up nonlinear models. Such an approach is based on the strong analogy between timedomain signal reconstruction from a set of samples and the continuous approximation of device nonlinear characteristics on the basis of a finite grid of measurements. According to this criterion, nonlinear empirical device modelling can be carried out by using, in the sampled voltage domain, typical methods of the time-domain sampling theory.

LOCAL DIGITAL CONTROL OF POWER ELECTRONIC CONVERTERS IN A DC MICROGRID BASED ON A-PRIORI DERIVATION OF SWITCHING SURFACES

In power electronic basedmicrogrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. The work presented in this dissertation proposes a generalized method of derivation of geometric manifolds in a dc microgrid that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energies in all the energy storage elements of the dc microgrid and power flowing into them. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will then be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller. The presence of switched power converters in microgrids involve different control actions for different system events. The control of the switch states of the converters is essential for steady state and transient operations. A digital memory look-up based controller that uses a hysteretic sliding mode control strategy is an effective technique to generate the proper switch states for the converters. An example dcmicrogrid with three dc-dc boost converters and resistive loads is considered for this work. The geometric manifolds are successfully generated for transient events, such as step changes in the loads and the sources. The surfaces corresponding to a specific case of step change in the loads are then used as reference surfaces in an EEPROM for experimentally validating the control strategy. The required switch states corresponding to this specific transient scenario are programmed in the EEPROM as a memory table. This controls the switching of the dc-dc boost converters and drives the system states to the reference manifold. In this work, it is shown that this strategy effectively controls the system for a transient condition such as step changes in the loads for the example case.

50 Years Ago We Marched: What began on the grounds of Lincoln University, ended on the steps of the Alabama State Capitol

LINCOLN UNIVERSITY - On March 25, 1965, a bus loaded with Lincoln University students and staff arrived in Montgomery, Ala. to join the Selma march for racial and voting equality. Although the Civil Rights Act of 1964 was in force, African-Americans continued to feel the effects of segregation. The 1960s was a decade of social unrest and change. In the Deep South, specifically Alabama, racial segregation was a cultural norm resistant to change. Governor George Wallace never concealed his personal viewpoints and political stance of the white majority, declaring “Segregation now, segregation tomorrow, segregation forever.” The march was aimed at obtaining African-Americans their constitutionally protected right to vote. However, Alabama’s deep-rooted culture of racial bias began to be challenged by a shift in American attitudes towards equality. Both black and whites wanted to end discrimination by using passive resistance, a movement utilized by Dr. Martin Luther King Jr. That passive resistance was often met with violence, sometimes at the hands of law enforcement and local citizens. The Selma to Montgomery march was a result of a protest for voting equality. The Student Nonviolent Coordinating Committee (SNCC) and the Southern Christian Leadership Counsel (SCLC) among other students marched along the streets to bring awareness to the voter registration campaign, which was organized to end discrimination in voting based on race. Violent acts of police officers and others were some of the everyday challenges protesters were facing. Forty-one participants from Lincoln University arrived in Montgomery to take part in the 1965 march for equality. Students from Lincoln University’s Journalism 383 class spent part of their 2015 spring semester researching the historical event. Here are their stories: Peter Kellogg “We’ve been watching the television, reading about it in the newspapers,” said Peter Kellogg during a February 2015 telephone interview. “Everyone knew the civil rights movement was going on, and it was important that we give him (Robert Newton) some assistance … and Newton said we needed to get involve and do something,” Kellogg, a lecturer in the 1960s at Lincoln University, discussed how the bus trip originated. “That’s why the bus happened,” Kellogg said. “Because of what he (Newton) did - that’s why Lincoln students went and participated.” “People were excited and the people along the sidewalk were supportive,” Kellogg said. However, the mood flipped from excited to scared and feeling intimidated. “It seems though every office building there was a guy in a blue uniform with binoculars standing in the crowd with troops and police. And if looks could kill me, we could have all been dead.” He says the hatred and intimidation was intense. Kellogg, being white, was an immediate target among many white people. He didn’t realize how dangerous the event in Alabama was until he and the others in the bus heard about the death of Viola Liuzzo. The married mother of five from Detroit was shot and killed by members of the Ku Klux Klan while shuttling activists to the Montgomery airport. “We found out about her death on the ride back,” Kellogg recalled. “Because it was a loss of life, and it shows the violence … we could have been exposed to that danger!” After returning to LU, Kellogg’s outlook on life took a dramatic turn. Kellogg noted King’s belief that a person should be willing to die for important causes. “The idea is that life is about something larger and more important than your own immediate gratification, and career success or personal achievements,” Kellogg said. “The civil rights movement … it made me, it made my life more significant because it was about something important.” The civil rights movement influenced Kellogg to change his career path and to become a black history lecturer. Until this day, he has no regrets and believes that his choices made him as a better individual. The bus ride to Alabama, he says, began with the actions of just one student. Robert Newton Robert Newton was the initiator, recruiter and leader of the Lincoln University movement to join Dr. Martin Luther King’s march in Selma. “In the 60s much of the civil rights activists came out of college,” said Newton during a recent phone interview. Many of the events that involved segregation compelled college students to fight for equality. “We had selected boycotts of merchants, when blacks were not allowed to try on clothes,” Newton said. “You could buy clothes at department stores, but no blacks could work at the department stores as sales people. If you bought clothes there you couldn’t try them on, you had to buy them first and take them home and try them on.” Newton said the students risked their lives to be a part of history and influence change. He not only recognized the historic event of his fellow Lincolnites, but also recognized other college students and historical black colleges and universities who played a vital role in history. “You had the S.N.C.C organization, in terms of voting rights and other things, including a lot of participation and working off the bureau,” Newton said. Other schools and places such as UNT, Greenville and Howard University and other historically black schools had groups that came out as leaders. Newton believes that much has changed from 50 years ago. “I think we’ve certainly come a long way from what I’ve seen from the standpoint of growing up outside of Birmingham, Alabama,” Newton said. He believes that college campuses today are more organized in their approach to social causes. “The campus appears to be some more integrated amongst students in terms of organizations and friendships.” Barbara Flint Dr. Barbara Flint grew up in the southern part of Arkansas and came to Lincoln University in 1961. She describes her experience at Lincoln as “being at Lincoln when the world was changing.“ She was an active member of Lincoln’s History Club, which focused on current events and issues and influenced her decision to join the Selma march. “The first idea was to raise some money and then we started talking about ‘why can’t we go?’ I very much wanted to be a living witness in history.” Reflecting on the march and journey to Montgomery, Flint describes it as being filled with tension. “We were very conscious of the fact that once we got on the road past Tennessee we didn’t know what was going to happen,” said Flint during a February 2015 phone interview. “Many of the students had not been beyond Missouri, so they didn’t have that sense of what happens in the South. Having lived there you knew the balance as well as what is likely to happen and what is not likely to happen. As my father use to say, ‘you have to know how to stay on that line of balance.’” Upon arriving in Alabama she remembers the feeling of excitement and relief from everyone on the bus. “We were tired and very happy to be there and we were trying to figure out where we were going to join and get into the march,” Flint said. “There were so many people coming in and then we were also trying to stay together; that was one of the things that really stuck out for me, not just for us but the people who were coming in. You didn’t want to lose sight of the people you came with.” Flint says she was keenly aware of her surroundings. For her, it was more than just marching forward. “I can still hear those helicopters now,” Flint recalled. “Every time the helicopters would come over the sound would make people jump and look up - I think that demonstrated the extent of the tenseness that was there at the time because the helicopters kept coming over every few minutes.” She said that the marchers sang “we are not afraid,” but that fear remained with every step. “Just having been there and being a witness and marching you realize that I’m one of those drops that’s going to make up this flood and with this flood things will move,” said Flint. As a student at Lincoln in 1965, Flint says the Selma experience undoubtedly changed her life. “You can’t expect to do exactly what you came to Lincoln to do,” Flint says. “That march - along with all the other marchers and the action that was taking place - directly changed the paths that I and many other people at Lincoln would take.” She says current students and new generations need to reflect on their personal role in society. “Decide what needs to be done and ask yourself ‘how can I best contribute to it?’” Flint said. She notes technology and social media can be used to reach audiences in ways unavailable to her generation in 1965. “So you don’t always have to wait for someone else to step out there and say ‘let’s march,’ you can express your vision and your views and you have the means to do so (so) others can follow you. Jaci Newsom Jaci Newsom came to Lincoln in 1965 from Atlanta. She came to Lincoln to major in sociology and being in Jefferson City was largely different from what she had grown up with. “To be able to come into a restaurant, sit down and be served a nice meal was eye-opening to me,” said Newsom during a recent interview. She eventually became accustomed to the relaxed attitude of Missouri and was shocked by the situation she encountered on an out-of-town trip. “I took a bus trip from Atlanta to Pensacola and I encountered the worse racism that I have ever seen. I was at bus stop, I went in to be served and they would not serve me. There was a policeman sitting there at the table and he told me that privately owned places could select not to serve you.” Newsom describes her experience of marching in Montgomery as being one with a purpose. “We felt as though we achieved something - we felt a sense of unity,” Newsom said. “We were very excited (because) we were going to hear from Martin Luther King. To actually be in the presence of him and the other civil rights workers there was just such enthusiasm and excitement yet there was also some apprehension of what we might encounter.” Many of the marchers showed their inspiration and determination while pressing forward towards the grounds of the Alabama Capitol building. Newsom recalled that the marchers were singing the lyrics “ain’t gonna let nobody turn me around” and “we shall overcome.” “ I started seeing people just like me,” Newsom said. “I don’t recall any of the scowling, the hitting, the things I would see on TV later. I just saw a sea of humanity marching towards the Capitol. I don’t remember what Martin Luther King said but it was always the same message: keep the faith; we’re going to get where we’re going and let us remember what our purpose is.” Newsom offers advice on what individuals can do to make their society a more productive and peaceful place. “We have come a long way and we have ways to change things that we did not have before,” Newsom said. “You need to work in positive ways to change.” Referencing the recent unrest in Ferguson, Mo., she believes that people become destructive as a way to show and vent anger. Her generation, she says, was raised to react in lawful ways – and believe in hope. “We have faith to do things in a way that was lawful and it makes me sad what people do when they feel without hope, and there is hope,” Newsom says. “Non-violence does work - we need to include everyone to make this world a better place.” Newsom graduated from Lincoln in 1969 and describes her experience at Lincoln as, “I grew up and did more growing at Lincoln than I think I did for the rest of my life.”

Time-Precision Flexible Arithmetic Unit

Paper submitted to the XVIII Conference on Design of Circuits and Integrated Systems (DCIS), Ciudad Real, España, 2003.

Architecture to Support Quality of Service in Arrowhead Systems

Presented at INForum - Simpósio de Informática (INFORUM 2015). 7 to 8, Sep, 2015. Covilhã, Portugal.

Efficiency Comparison of DFT/IDFT Algorithms by Evaluating Diverse Hardware Implementations

In this paper we investigate various algorithms for performing Fast Fourier Transformation (FFT)/Inverse Fast Fourier Transformation (IFFT), and proper techniques for maximizing the FFT/IFFT execution speed, such as pipelining or parallel processing, and use of memory structures with pre-computed values (look up tables -LUT) or other dedicated hardware components (usually multipliers). Furthermore, we discuss the optimal hardware architectures that best apply to various FFT/IFFT algorithms, along with their abilities to exploit parallel processing with minimal data dependences of the FFT/IFFT calculations. An interesting approach that is also considered in this paper is the application of the integrated processing-in-memory Intelligent RAM (IRAM) chip to high speed FFT/IFFT computing. The results of the assessment study emphasize that the execution speed of the FFT/IFFT algorithms is tightly connected to the capabilities of the FFT/IFFT hardware to support the provided parallelism of the given algorithm. Therefore, we suggest that the basic Discrete Fourier Transform (DFT)/Inverse Discrete Fourier Transform (IDFT) can also provide high performances, by utilizing a specialized FFT/IFFT hardware architecture that can exploit the provided parallelism of the DFT/IDF operations. The proposed improvements include simplified multiplications over symbols given in polar coordinate system, using sinе and cosine look up tables, and an approach for performing parallel addition of N input symbols.

Efficiency Comparison of DFT/IDFT Algorithms by Evaluating Diverse Hardware : Implementations,Parallelization Prospectsand Possible Improvements

In this paper we investigate various algorithms for performing Fast Fourier Transformation (FFT)/Inverse Fast Fourier Transformation (IFFT), and proper techniquesfor maximizing the FFT/IFFT execution speed, such as pipelining or parallel processing, and use of memory structures with pre-computed values (look up tables -LUT) or other dedicated hardware components (usually multipliers). Furthermore, we discuss the optimal hardware architectures that best apply to various FFT/IFFT algorithms, along with their abilities to exploit parallel processing with minimal data dependences of the FFT/IFFT calculations. An interesting approach that is also considered in this paper is the application of the integrated processing-in-memory Intelligent RAM (IRAM) chip to high speed FFT/IFFT computing. The results of the assessment study emphasize that the execution speed of the FFT/IFFT algorithms is tightly connected to the capabilities of the FFT/IFFT hardware to support the provided parallelism of the given algorithm. Therefore, we suggest that the basic Discrete Fourier Transform (DFT)/Inverse Discrete Fourier Transform (IDFT) can also provide high performances, by utilizing a specialized FFT/IFFT hardware architecture that can exploit the provided parallelism of the DFT/IDF operations. The proposed improvements include simplified multiplications over symbols given in polar coordinate system, using sinе and cosine look up tables,and an approach for performing parallel addition of N input symbols.

Tecnologia .NET : Hotel SPA

Treball de Fi de Carrera sobre la tecnologia .NET de Microsoft. En aquest treball s'ha creat un servei WCF i una petita aplicació de consola per hostatjar-lo. Aquest servei utilitza unes classes de LINQ To SQL per accedir a la base de dades. L'aplicació HotelSpaWPF, creada amb WPF i XAML, consumeix el servei WCF per treballar amb la informació de que es disposa a la base de dades.L'aplicació d'escriptori HotelSpaWPF consta de dues parts, la part corresponent als clients de l'hotel, on podran consultar el serveis, activitats i recursos oferts així com fer peticions, inscripcions o reserves. La part d'administrador permet gestionar tota aquesta informació.

A virtual backbone based approach for cooperative caching in mobile ad hoc networks

Cache look up is an integral part of cooperative caching in ad hoc networks. In this paper, we discuss a cooperative caching architecture with a distributed cache look up protocol which relies on a virtual backbone for locating and accessing data within a cooperate cache. Our proposal consists of two phases: (i) formation of a virtual backbone and (ii) the cache look up phase. The nodes in a Connected Dominating Set (CDS) form the virtual backbone. The cache look up protocol makes use of the nodes in the virtual backbone for effective data dissemination and discovery. The idea in this scheme is to reduce the number of nodes involved in cache look up process, by constructing a CDS that contains a small number of nodes, still having full coverage of the network. We evaluated the effect of various parameter settings on the performance metrics such as message overhead, cache hit ratio and average query delay. Compared to the previous schemes the proposed scheme not only reduces message overhead, but also improves the cache hit ratio and reduces the average delay

COMP6037 Seminar 23 10 13: Science, knowledge and technology

Set readings 1. Sismondo S. (2009). The Kuhnian revolution. In An introduction to science and technology studies. p12-22 2. Ben-David J, Sullivan T. (1975) Sociology of science. Annual Review of Sociology p203-21 3. Clarke A, Star SL. (2008) The social worlds framework: a theory/methods package. In Hackett EJ et al. The handbook of science and technology studies. Cambridge MA: MIT Press p113-137 Bonus paper (read if you have time) 4. Mitroff I. (1974). Norms and Counternorms in a Select Group of Apollo Moon Scientists. American Sociological Review 39:79-95 • Aim to ensure that you understand the core arguments of each paper • Look up/note any new terminology (and questions you want to ask) • Think about your critical appraisal of the paper (what are the merits/demerits of the argument, evidence etc) In the seminar we will spend about 5 minutes talking about each paper, and then - building on the two lectures - discuss how these ideas might be used to think about the Web and Web Science. At the end there will be some time for questions and a chance to note your key learning points.

Dialetos Gestuais em Portugal

Os dialetos das línguas orais consistem numa variação linguística que se pode concretizar, sobretudo em alterações fonológicas e lexicais que derivam da diferenciação geográfica. Na língua gestual portuguesa (LGP) parece verificar-se o mesmo fenómeno, embora a motivação para a variação linguística possa não ser apenas geográfica. A presente dissertação de Mestrado pretende estudar os dialetos em língua gestual portuguesa, registando, para o efeito, gestos produzidos e analisados por surdos de diferentes regiões do país. Em particular, pretendem analisar-se as variantes dialetais utilizadas por surdos que tenham frequentado diferentes escolas e espaços de convívio. Serão também investigadas as relações de poder local que envolvem a escolha de determinados gestos pelos usuários da língua.

A Framework supporting collaboration on the distributed design of integrated systems

The work described in this thesis aims to support the distributed design of integrated systems and considers specifically the need for collaborative interaction among designers. Particular emphasis was given to issues which were only marginally considered in previous approaches, such as the abstraction of the distribution of design automation resources over the network, the possibility of both synchronous and asynchronous interaction among designers and the support for extensible design data models. Such issues demand a rather complex software infrastructure, as possible solutions must encompass a wide range of software modules: from user interfaces to middleware to databases. To build such structure, several engineering techniques were employed and some original solutions were devised. The core of the proposed solution is based in the joint application of two homonymic technologies: CAD Frameworks and object-oriented frameworks. The former concept was coined in the late 80's within the electronic design automation community and comprehends a layered software environment which aims to support CAD tool developers, CAD administrators/integrators and designers. The latter, developed during the last decade by the software engineering community, is a software architecture model to build extensible and reusable object-oriented software subsystems. In this work, we proposed to create an object-oriented framework which includes extensible sets of design data primitives and design tool building blocks. Such object-oriented framework is included within a CAD Framework, where it plays important roles on typical CAD Framework services such as design data representation and management, versioning, user interfaces, design management and tool integration. The implemented CAD Framework - named Cave2 - followed the classical layered architecture presented by Barnes, Harrison, Newton and Spickelmier, but the possibilities granted by the use of the object-oriented framework foundations allowed a series of improvements which were not available in previous approaches: - object-oriented frameworks are extensible by design, thus this should be also true regarding the implemented sets of design data primitives and design tool building blocks. This means that both the design representation model and the software modules dealing with it can be upgraded or adapted to a particular design methodology, and that such extensions and adaptations will still inherit the architectural and functional aspects implemented in the object-oriented framework foundation; - the design semantics and the design visualization are both part of the object-oriented framework, but in clearly separated models. This allows for different visualization strategies for a given design data set, which gives collaborating parties the flexibility to choose individual visualization settings; - the control of the consistency between semantics and visualization - a particularly important issue in a design environment with multiple views of a single design - is also included in the foundations of the object-oriented framework. Such mechanism is generic enough to be also used by further extensions of the design data model, as it is based on the inversion of control between view and semantics. The view receives the user input and propagates such event to the semantic model, which evaluates if a state change is possible. If positive, it triggers the change of state of both semantics and view. Our approach took advantage of such inversion of control and included an layer between semantics and view to take into account the possibility of multi-view consistency; - to optimize the consistency control mechanism between views and semantics, we propose an event-based approach that captures each discrete interaction of a designer with his/her respective design views. The information about each interaction is encapsulated inside an event object, which may be propagated to the design semantics - and thus to other possible views - according to the consistency policy which is being used. Furthermore, the use of event pools allows for a late synchronization between view and semantics in case of unavailability of a network connection between them; - the use of proxy objects raised significantly the abstraction of the integration of design automation resources, as either remote or local tools and services are accessed through method calls in a local object. The connection to remote tools and services using a look-up protocol also abstracted completely the network location of such resources, allowing for resource addition and removal during runtime; - the implemented CAD Framework is completely based on Java technology, so it relies on the Java Virtual Machine as the layer which grants the independence between the CAD Framework and the operating system. All such improvements contributed to a higher abstraction on the distribution of design automation resources and also introduced a new paradigm for the remote interaction between designers. The resulting CAD Framework is able to support fine-grained collaboration based on events, so every single design update performed by a designer can be propagated to the rest of the design team regardless of their location in the distributed environment. This can increase the group awareness and allow a richer transfer of experiences among them, improving significantly the collaboration potential when compared to previously proposed file-based or record-based approaches. Three different case studies were conducted to validate the proposed approach, each one focusing one a subset of the contributions of this thesis. The first one uses the proxy-based resource distribution architecture to implement a prototyping platform using reconfigurable hardware modules. The second one extends the foundations of the implemented object-oriented framework to support interface-based design. Such extensions - design representation primitives and tool blocks - are used to implement a design entry tool named IBlaDe, which allows the collaborative creation of functional and structural models of integrated systems. The third case study regards the possibility of integration of multimedia metadata to the design data model. Such possibility is explored in the frame of an online educational and training platform.

NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations

Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measuring total ozone twice daily with limited sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS spectral parameters and the calculation of air mass factors (AMF) needed for the conversion of O-3 slant column densities into vertical column amounts. The most important improvement is the use of O-3 AMF look-up tables calculated using the TOMS V8 (TV8) O-3 profile climatology, that allows accounting for the dependence of the O-3 AMF on the seasonal and latitudinal variations of the O-3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Systeme d'Analyse par Observation Zenithale) network. The revised SAOZ ozone data from eight stations deployed at all latitudes have been compared to TOMS, GOMEGDP4, SCIAMACHY-TOSOMI, SCIAMACHY-OL3, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments at Observatoire de Haute Provence (44 degrees N, 5.5 degrees E) and Sodankyla (67 degrees N, 27 degrees E), respectively. A significantly better agreement is obtained between SAOZ and correlative reference ground-based measurements after applying the new O-3 AMFs. However, systematic seasonal differences between SAOZ and satellite instruments remain. These are shown to mainly originate from (i) a possible problem in the satellite retrieval algorithms in dealing with the temperature dependence of the ozone cross-sections in the UV and the solar zenith angle (SZA) dependence, (ii) zonal modulations and seasonal variations of tropospheric ozone columns not accounted for in the TV8 profile climatology, and (iii) uncertainty on the stratospheric ozone profiles at high latitude in the winter in the TV8 climatology. For those measurements mostly sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, or to SZA like SCIAMACHY-TOSOMI, the application of temperature and SZA corrections results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.