On the effect of power amplifier nonlinearity on MIMO transmit diversity systems

Nonlinearity of high-power amplifier (HPA) plays a crucial role in the performance of multiple-input multiple-output (MIMO) systems. In this paper, we investigate the performance of MIMO orthogonal space-time block coding (STBC) systems in the presence of nonlinear HPA. Specifically, we assess the impact of HPA nonlinearity on the average symbol error probability (SEP), total degradation (TD), and system capacity of orthogonal STBC in uncorrelated Nakagami-m fading channels. Numerical results are provided and show the effects of several system parameters, such as the output back-off (OBO) of nonlinear HPA, numbers of transmit and receive antennas, and modulation order of quadrature amplitude modulation (QAM), on performance.

An anatomy of the cooling of the North Atlantic Ocean in the 1960s and 1970s

In the 1960s and early 1970s sea surface temperatures in the North Atlantic Ocean cooled rapidly. There is still considerable uncertainty about the causes of this event, although various mechanisms have been proposed. In this observational study it is demonstrated that the cooling proceeded in several distinct stages. Cool anomalies initially appeared in the mid-1960s in the Nordic Seas and Gulf Stream Extension, before spreading to cover most of the Subpolar Gyre. Subsequently, cool anomalies spread into the tropical North Atlantic before retreating, in the late 1970s, back to the Subpolar Gyre. There is strong evidence that changes in atmospheric circulation, linked to a southward shift of the Atlantic ITCZ, played an important role in the event, particularly in the period 1972-76. Theories for the cooling event must account for its distinctive space-time evolution. Our analysis suggests that the most likely drivers were: 1) The “Great Salinity Anomaly” of the late 1960s; 2) An earlier warming of the subpolar North Atlantic, which may have led to a slow-down in the Atlantic Meridional Overturning Circulation; 3) An increase in anthropogenic sulphur dioxide emissions. Determining the relative importance of these factors is a key area for future work.

Modelling capability and affordance as properties of human/machine resource systems

Understanding how and why the capability of one set of business resources, its structural arrangements and mechanisms compared to another works can provide competitive advantage in terms of new business processes and product and service development. However, most business models of capability are descriptive and lack formal modelling language to qualitatively and quantifiably compare capabilities, Gibson’s theory of affordance, the potential for action, provides a formal basis for a more robust and quantitative model, but most formal affordance models are complex and abstract and lack support for real-world applications. We aim to understand the ‘how’ and ‘why’ of business capability, by developing a quantitative and qualitative model that underpins earlier work on Capability-Affordance Modelling – CAM. This paper integrates an affordance based capability model and the formalism of Coloured Petri Nets to develop a simulation model. Using the model, we show how capability depends on the space time path of interacting resources, the mechanism of transition and specific critical affordance factors relating to the values of the variables for resources, people and physical objects. We show how the model can identify the capabilities of resources to enable the capability to inject a drug and anaesthetise a patient.

Design of delay-tolerant space–time codes with limited feedback

In cooperative communication networks, owing to the nodes' arbitrary geographical locations and individual oscillators, the system is fundamentally asynchronous. Such a timing mismatch may cause rank deficiency of the conventional space-time codes and, thus, performance degradation. One efficient way to overcome such an issue is the delay-tolerant space-time codes (DT-STCs). The existing DT-STCs are designed assuming that the transmitter has no knowledge about the channels. In this paper, we show how the performance of DT-STCs can be improved by utilizing some feedback information. A general framework for designing DT-STC with limited feedback is first proposed, allowing for flexible system parameters such as the number of transmit/receive antennas, modulated symbols, and the length of codewords. Then, a new design method is proposed by combining Lloyd's algorithm and the stochastic gradient-descent algorithm to obtain optimal codebook of STCs, particularly for systems with linear minimum-mean-square-error receiver. Finally, simulation results confirm the performance of the newly designed DT-STCs with limited feedback.

Exploring invention capability

Research on invention has focused on business invention and little work has been conducted on the process and capability required for the individual inventor or the capabilities required for an advice to be considered an invention. This paper synthesises the results of an empirical survey of ten inventor case studies with current research on invention and recent capability affordance research to develop an integrated capability process model of human capabilities for invention and specific capabilities of an invented device. We identify eight necessary human effectivities required for individual invention capability and six functional key activities using these effectivities, to deliver the functional capability of invention. We also identified key differences between invention and general problem solving processes. Results suggest that inventive step capability relies on a unique application of principles that relate to a new combination of affordance chain with a new mechanism and or space time (affordance) path representing the novel way the device works, in conjunction with defined critical affordance operating factors that are the subject of the patent claims.

A systematic method of parameterisation estimation using data assimilation

In numerical weather prediction, parameterisations are used to simulate missing physics in the model. These can be due to a lack of scientific understanding or a lack of computing power available to address all the known physical processes. Parameterisations are sources of large uncertainty in a model as parameter values used in these parameterisations cannot be measured directly and hence are often not well known; and the parameterisations themselves are also approximations of the processes present in the true atmosphere. Whilst there are many efficient and effective methods for combined state/parameter estimation in data assimilation (DA), such as state augmentation, these are not effective at estimating the structure of parameterisations. A new method of parameterisation estimation is proposed that uses sequential DA methods to estimate errors in the numerical models at each space-time point for each model equation. These errors are then fitted to pre-determined functional forms of missing physics or parameterisations that are based upon prior information. We applied the method to a one-dimensional advection model with additive model error, and it is shown that the method can accurately estimate parameterisations, with consistent error estimates. Furthermore, it is shown how the method depends on the quality of the DA results. The results indicate that this new method is a powerful tool in systematic model improvement.

Experimental identification of chaotic fibers

In a 2D parameter space, by using nine experimental time series of a Clitia`s circuit, we characterized three codimension-1 chaotic fibers parallel to a period-3 window. To show the local preservation of the properties of the chaotic attractors in each fiber, we applied the closed return technique and two distinct topological methods. With the first topological method we calculated the linking, numbers in the sets of unstable periodic orbits, and with the second one we obtained the symbolic planes and the topological entropies by applying symbolic dynamic analysis. (C) 2007 Elsevier Ltd. All rights reserved.

Exact vortex solutions in a CP(N) Skyrme-Faddeev type model

We consider a four dimensional field theory with target space being CP(N) which constitutes a generalization of the usual Skyrme-Faddeev model defined on CP(1). We show that it possesses an integrable sector presenting an infinite number of local conservation laws, which are associated to the hidden symmetries of the zero curvature representation of the theory in loop space. We construct an infinite class of exact solutions for that integrable submodel where the fields are meromorphic functions of the combinations (x(1) + i x(2)) and (x(3) + x(0)) of the Cartesian coordinates of four dimensional Minkowski space-time. Among those solutions we have static vortices and also vortices with waves traveling along them with the speed of light. The energy per unity of length of the vortices show an interesting and intricate interaction among the vortices and waves.

Discursos e a construção do "real": um estudo do processo de formação e institucionalização do campo da biotecnologia

Comprehension of the processes of formation of new organizational fields is the main objective that stimulated the theoretical reflection and empirical research that I present in this paper. My intention here is to uphold the potential for the application of seemingly dichotomous perspectives in terms of the objectivity/subjectivity dimension in the comprehension of the objective in question. The contribution of Foucault, with his concept of discourse, is linked to the proposal of critical constructivism represented by Latour and studies of science and technology. Juxtaposing these perspectives, I examined the dynamics of the biotechnological field on the basis of the dialectic of movements of demarcation/circularity, which is basically a simultaneous movement of (dis)construction of the boundaries of a field. The dialectic of demarcation/circularity is made up of the set of relations established between heterogeneous elements ¿ institutions, economic and social processes, behavioral patterns, systems of norms, techniques, types of classification, forms of characterization, in other words it finds ways of emerging in the course of discursive formations. This theoretical proposal ¿ which incorporates an overlooked dimension in institutional analysis, especially in organization studies (power) ¿ has the advantage of contributing to enhancing comprehension of the dynamics of institutionalization. By proposing that the institutional processes arise within discursive fields, the argument put forward is that such processes contribute to the productivity of the power relations in these fields. In empirical terms, I conducted a descriptive and exploratory research directed at the biotechnology sector. The research was based on a historical perspective, since the analysis spans the period from the origins of genetic science (beginning of the 20th century) through to recent developments in biotechnology in the USA (beginning of the 21st century). The USA was chosen as the locus of research, principally due to the fact that structuring of the field of biotechnology originated in that country, subsequently spreading to other countries around the world. Starting from this theoretical and methodological framework, three discursive formations are highlighted: organization, information and network. Each of the discursive formations is characterized by a dominant set of discourses that prepare the ground for the appearance and (trans)formation of the focus-objects under analysis. In this process, organizations appear in at least two ways: as boundary-organizations ¿ which are important for understanding the movement of the approximation of different discursive domains ¿ and as new organizations, which accompany the (trans)formation of new fields, whereby prevailing discourses materialize at a given historical moment and contribute to breathe life into new discourses, which in turn spark off new power relations. Among the conclusions of this work, I would highlight the following: questioning the 'organizational' dimension of the fields; the relationship revealed not only between the discourses and the institutionalized practices, but also with the process of construction of legitimacy; and the redefinition of the concept of organizations, based on new conceptions relating to the limits of the topic, the objectivity/subjectivity, and space/time dichotomy.

Trabalho e família no contexto de teletrabalho: o olhar de teletrabalhadores e seus co-residentes

Esta dissertação tem como objetivo contribuir para o conhecimento sobre o teletrabalho, especialmente, sobre a dinâmica da realização do trabalho na esfera familiar, a partir do home-office telework. Investigou-se de que maneira os teletrabalhadores e sua família dão sentido aos dilemas, oportunidades e exigências da realização do trabalho no ambiente familiar, à luz de suas práticas discursivas. Para tanto, entrevistas semi-estruturadas foram realizadas com 25 teletrabalhadores e seus co-residentes e analisadas sob a ótica da análise de conteúdo. A pesquisa revela que quando a casa dá lugar às atividades profissionais do indivíduo, as relações entre as demandas pessoais, familiares e profissionais se tornam mais próximas, diluídas e entrelaçadas. A aproximação das esferas de trabalho e não-trabalho conduz a uma ruptura nas dinâmicas espaciais, temporais e psicológicas desses domínios, proporcionando aos indivíduos oportunidades de desenvolvimento pessoal. No entanto, as mudanças pelas quais os mesmos terão de passar apresentam potencialidades contraditórias. Ao mesmo tempo em que o teletrabalho proporciona uma oportunidade de integração com a família e flexibilidade para o melhor aproveitamento do tempo de trabalho e não-trabalho, a dificuldade de equilibrar dois mundos construídos sobre discursos diversos, o mundo da casa e da rua, pode despontar uma crise, dependendo do preparo de cada família para essa situação de trabalho. A fim de auxiliar na interpretação dos resultados, os pontos de conteúdo mais expressivos, os quais ilustram o exposto acima, foram expostos em quatro temas relacionados ao telehomework: espaço, flexibilidade de tempo, gênero e equilíbrio trabalho-vida pessoal.

Henri Lefebvre: possibilidades teórico-metodológicas para Arquitetura e urbanismo

This paper presents the theoretical-methodological possibilities of the French philosopher and sociologist Henri Lefebvre, for the discipline of architecture and urbanism in an effort to overcome the fragmentation imposed by the institutionalization of science in general. From Du rural à l'urbain (Lefebvre, 1970) compilation, it brings the author's other works from the period between 1968 and 1974, indicating the conduits for reflection and their interrelationships with methods, types of analyses and other procedures to treat the space-time urban. The methodology involves a research on the author s 'today and yesterday' in the scientific field, a research and analysis of his procedures in highlight of philosophical, social, economic and political aspects, the historical context of his references and provides significant and possible elements for the study, research and extension in the area in question

Narrativas do Brasil nas memórias de Pedro Nava

This thesis is a translation of work of the Brazilian doctor, Pedro da Silva Nava (1903-1984), in particular, his memoirs and chronicles, articulated with the writings of medicine history, aiming to defend that the autobiographical narratives are sources of research capable of promoting discussions on the expansion of the present at the confluence of complex and unequal society in constant changing process as the Brazilian. The theoretical and methodological support circulates around studies, proposals and thesis by Boaventura Santos about empowering past, destabilizing subjectivity, sociology of absences, cosmopolitan reason and translation work. The empirical support drawn from the literature produced by Nava were analyzed with reference this reasoning and studies that have facilitated the flow of translation among others, the studies of Antonio Candido, Arrigucci Jr., Boris Cyrulnik, Beatriz Sarlo, Ecléa Bosi, Ítalo Calvino, José Willington Germano, José Maria Cançado, Lev Vygotsky, Marilena Chauí, Paul Ricöeur and Walter Benjamim, without neglecting what we consider indispensable to scientific research, the production of relevant knowledge and prudent, in view of a decent life. The initial inflections reflect the subject of the Memoirs and its education/training, to then place the Memoir subject in the literary context, scientific, historical and Brazilian poetic (1972-2010), bringing great interpreters and discussing the rationale used by the Narrator that we defend stand closer to the cosmopolitan, showing the formation of narratives whose presence insert itself beforehand to modernist verve, linked to the discursive array against the literature as domination space, disseminated in Brazil in the early twentieth century. So, it articulate with those in which the concerns adjust the construction of the social formation of Brazil as a national heritage through literary narrative that focuses on a historical principle that becomes the past empowering, allowing his rereading, whose converge to memory, the lifestyles, the plurality of language and Brazilian culture, formed by several people, converging into a design not of culture but multiculturalism in Brazil. The memory issue was addressed in the space-time of experiences of being that narrates, shaped by a destabilizing subjectivity that sought to order the testimony of a time, a history and society, retelling them by creative imagination, almost fictional, to make circulate his knowledge about Brazil attached to his medical knowledge, as well as other subjects in his living group and other groups with whom they maintained contact. Thus, he portrayed both tangible and intangible cultural assets of the country as a form of preservation, giving them meanings and sense. It approaches, therefore, from the perspective of sociology of absences, the expansion of the present and by the logic inherent in his narratives of self and Brazil

Narrativa autobiográfica como prática de formação e de atualização de si : os grupos referência e o grupo reflexivo na mediação da constituição identitária docente

The thesis: "autobiographical narrative as practical continuous training and updating of itself: the groups-reference and the reflexive group in the mediation of identity construction of teaching" begins in the founder matter: "What are the implications of groups-reference in the process of identity formation and the teaching role of teachers which is participating of the research? This object of study deals with the continuing education of teachers of Basic Education and the role of the reflective group as space-time of (re) construction of educational knowledge, for the recognition of yourself. The thesis defends that the autobiographical narrative, as a pedagogical tool and research, for the initial and continuous training, is presented as theoretical and methodological foundation necessary for identity formation of the teacher. The research is limited to the qualitative approach with a focus on the autobiographical narrative. The participants are six teachers, three teachers and three students-teachers. The corpus comprises six autobiographical narratives, six reports of successful experiences, two studies on the biographical work, and six individual testimonials about the impact in personal and professional life. The data analysis was to reference Dausien and Alheit (2006), Bruner (1997), Contreras (2002), Delory-Momberger (2007), Freire (2005), Giddens (2002), Josso (2004), new (1988, 2002), Passeggi (2001, 2002), Pineau (2004), Ricoeur (2004), Souza (2006), Tardif (2002) and Vygotsky (2005). The research revealed that the formation of identity as a teachers of the educators occurred in the reference group, involving the formal, non-formal and informal of the processes of knowledge , in a movement of alternation training that includes yourself, the other and the ambient. Also revealed that the pedagogical choices of the teachers studied aimed at minimizing educational gaps that were lived in both field personal and social; that the personal identity is configured as an identity narrative and the methodology of the biographical work, through the mimesis of continuing education, provided the passage from the group reflective to the group of reference

O processo de invenção de si: um estudo sobre a construção identitária de pedagogas em formação

This work was developed in the course of Pedagogy, Universidade Federal do Rio Grande do Norte. Aims to understand the process of identity construction of teachers and educators in initial training. We started from the idea that such process was made by a complex and interdependent movement, once it was an inventive phenomenon wrought by individuals who are authors and actors of the story of their "real life" (KAUFMANN). This identity is rooted in the trajectories and social biographical experiences (FERREIRA), relationships with the constructed and accumulated knowledge in this route (CHARLOT) and in the developing of a sense of cultural belonging institutionally constructed (Luckmann, Berger). Then, the training involves relationships with knowledge in several instances, considering the effects, in one hand, the historic-social production and, in another hand, from the positions of subject and their biographical itinerary, existential and formative. We used the methodology of the Comprehensive Interview (KAUFMANN; SILVA), associated with a network of theoretical references, empirical and very analytical and interpretive activity. She researcher also relied on the "sensitive listening" (BARBIER), empathic attitude of "listening / seeing" the subject, and the notion of "intellectual artisan" (MILLS). The individual interviews were supplemented by the Focus Group. The approach was multi-referential (ARDOINO; MACEDO), with the intertwining of different perspectives, allowing a more complex configuration and less reductionist. In the analysis and interpretation we located the starting point, genesis of identity whose dynamics is not rigidly determined, but localized in space-time that precedes entry into the initial training. It is the time of concerns, questions and reflections about what you want to be in the future professional life. In sequence, we saw the route, multifaceted process whose the direction is the increasing involvement of individuals with their training. This training is engendered by the relations with the curricular, extracurricular and discursive knowledge, as simultaneous dynamics of self training and socio training. The self training of the individuals, understanding the critical, ethic and authority reading of their own experiences, is also seen as an exercise of shared responsibility, it assumes that the relationship with others meanings and professor mediation. The socio training refers to the collective subject and turns to the historical production and diversified knowledge, and comprehension of the various training instances. Self training and socio training are both objects of negotiation, because they are provocative of new designs, and cultural and identity maps, mobilizing the senses towards new meanings of themselves and the professional reality. It is in this interdependence between what is historically produced and the experiences of the subjects, who we located the arrival, considering it as a radically incomplete process of the professional identity and the building itself.

O sensível no trabalho docente: representação social entre docentes do Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte

The aim of this study was to analyze the social representation of the sensible among teachers of the Federal Institute of Education, Science and Technology of Rio Grande do Norte, attempting to identify its constituents and understand the dynamics that gives functionality to your organization. The study is significant considering that the professional conduct can not be delineated in its complexity without unraveling the social representations that teachers themselves have of their being and doing professional. The theoretical and methodological framework of the research is the theory of social representation. 107 teachers from various backgrounds participated. To collect the data were used as instruments : a questionnaire listing, which subsidizes the characterization of the subjects , the TALP - technique of free association of words ( ABRIC , 1994) , the PCM - Procedure for Multiple Ratings ( ROAZZI , 1995) ; questionnaire redemption of sensitive memories of the subjects in their school experiences of childhood , adolescence, youth and teaching practice . The PCM data, in which the slogan was directed at rating Give class, were submitted to multidimensional statistical analysis. Already TALP was analyzed by EVOC 2000 software, the profile questionnaire received descriptive statistical analysis and the memories received the questionnaire analysis of thematic content, Bardin (2004). Taken together, the results point to a social representation of sensitive teaching (the game, the fun, the touch, the smile, the relaxation) are not in the classroom. The sensitive pure still fits in school, but only in the courtyard, on the playground, in the intervals, therefore, outside of space-time class, playful perch that lives in each of us is totally strange to this world of the classroom . After doing the Approximation of ideas , we realized three discourses evident in the reports of teachers : the discourse of Numbness in which we perceive the distance of the teacher in relation to sensitive component as a facilitator in the learning process , the discourse of Feeling , in which we can discern small approximation to the sensitive dialogues and proposed in this study , the speech of reflection in which teachers analyze, evaluate and establish a discourse on the importance of education in sensitive , but not actualize in their teaching practice