Assessing an FPGA implemented MIMO testbed with the use of channel emulator

In this paper, a channel emulator for assessing the performance of MIMO testbed implemented in a field programmable gate array technology is described. The FPGA based MIMO system includes a signal generator, modulation/demodulation and space time coding/decoding modules. The emulator uses information about a wireless channel from computer simulations or actual measurements. In simulations, a single bounce scattering model for an indoor environment is applied. The generated data is stored in the FPGA board. The tests are performed for a 2times2 MIMO system that uses Alamouti scheme for space coding/decoding. The performed tests show proper operation of the FPGA implemented MIMO testbed. Good agreement between the results using measured and simulated channel data is obtained.

Design of MIMO testbed with an FPGA board for fast signal processing

This paper describes the design of a Multiple Input Multiple Output testbed for assessing various MIMO transmission schemes in rich scattering indoor environments. In the undertaken design, a Field Programmable Gate Array (FPGA) board is used for fast processing of Intermediate Frequency signals. At the present stage, the testbed performance is assessed when the channel emulator between transmitter and receiver modules is introduced. Here, the results are presented for the case when a 2x2 Alamouti scheme for space time coding/decoding at transmitter and receiver is used. Various programming details of the FPGA board along with the obtained simulation results are reported

COMUNICAÇÃO & ASTRONOMIA: UMA UNIÃO VIRTUAL Estudos para uma teoria de comunicação organizacional on-line a partir do caso Rede de Astronomia Observacional REA/Brasil

A tese Comunicação & Astronomia, uma união virtual aborda o universo da comunicação virtual, das organizações virtuais, da ciência virtual. Um universo novo e emocionante onde a relação assíncrona espaço-temporal é o fator comum a todos os atores sociais envolvidos. O universo do virtual, das ferramentas de comunicação relacionadas às novas tecnologias, do ciberespaço, da existência concreta de uma organização imaterial. Estes elementos abrem novos horizontes para o conhecimento e compreensão dos processos de comunicação humana e organizacional na era da revolução informacional, proporcionando a oportunidade de estabelecer uma teoria de comunicação organizacional on line. A pesquisa bibliográfica apoiou-se em três bases teóricas de referência: a comunicação mediada por computador, comunicação virtual e comunicação organizacional, estas bases tiveram ainda o suporte de um estudo de caso que constituiu o corpus da pesquisa. Pudemos então compreender como ocorre a comunicação em uma organização virtual, seus processos, ferramentas e pontos cruciais que podem ser resumidos no fator motivacional necessário ao estímulo à interação virtual cooperativa, necessidade de construção e manutenção de imagem institucional forte que delimite a organização no ciberespaço e definição clara dos códigos de conduta da organização virtual.(AU)

Derivations of variational gaussian process approximation framework

Recently, within the VISDEM project (EPSRC funded EP/C005848/1), a novel variational approximation framework has been developed for inference in partially observed, continuous space-time, diffusion processes. In this technical report all the derivations of the variational framework, from the initial work, are provided in detail to help the reader better understand the framework and its assumptions.

Natural images dominate in binocular rivalry

Ecological approaches to perception have demonstrated that information encoding by the visual system is informed by the natural environment, both in terms of simple image attributes like luminance and contrast, and more complex relationships corresponding to Gestalt principles of perceptual organization. Here, we ask if this optimization biases perception of visual inputs that are perceptually bistable. Using the binocular rivalry paradigm, we designed stimuli that varied in either their spatiotemporal amplitude spectra or their phase spectra. We found that noise stimuli with “natural” amplitude spectra (i.e., amplitude content proportional to 1/f, where f is spatial or temporal frequency) dominate over those with any other systematic spectral slope, along both spatial and temporal dimensions. This could not be explained by perceived contrast measurements, and occurred even though all stimuli had equal energy. Calculating the effective contrast following attenuation by a model contrast sensitivity function suggested that the strong contrast dependency of rivalry provides the mechanism by which binocular vision is optimized for viewing natural images. We also compared rivalry between natural and phase-scrambled images and found a strong preference for natural phase spectra that could not be accounted for by observer biases in a control task. We propose that this phase specificity relates to contour information, and arises either from the activity of V1 complex cells, or from later visual areas, consistent with recent neuroimaging and single-cell work. Our findings demonstrate that human vision integrates information across space, time, and phase to select the input most likely to hold behavioral relevance.

Wage spillovers, inter-regional effects and the impact of inward investment

This paper evaluates the extent of inter-industry and inter-regional wage spillovers across the UK. An extensive body of literature exists suggesting that wages elsewhere affect wage determination and levels of satisfaction, but this paper extends the analysis of wage determination to examine the effects of inward investment in the process. Thus far the specific effect of foreign wages on domestic wage determination has not been evaluated. We employ industry- and regional-level panel data for the UK, and contrast results from alternative approaches to space-time modelling. Each supports the notion that such wage spillovers do occur, though assumptions made concerning the modelling of spatial interaction are important. Further, such wage spillovers are more widespread for skilled than for unskilled workers and also lower in areas of high unemployment. © 2006 Regional Studies Association.

FlexSIG-Flexible software inspection groupware

The objective of this research is to design and build a groupware system which will allow members of a distributed group more flexibility in performing software inspection. Software inspection, which is part of non-execution based testing in software development, is a group activity. The groupware system aims to provide a system that will improve acceptability of groupware and improve software quality by providing a software inspection tool that is flexible and adaptable. The groupware system provide a flexible structure for software inspection meetings. The groupware system will extend the structure of the software inspection meeting itself, allowing software inspection meetings to use all four quadrant of the space-time matrix: face-to-face, distributed synchronous, distributed asynchronous, and same place-different time. This will open up new working possibilities. The flexibility and adaptability of the system allows work to switch rapidly between synchronous and asynchronous interaction. A model for a flexible groupware system was developed. The model was developed based on review of the literature and questionnaires. A prototype based on the model was built using java and WWW technology. To test the effectiveness of the system, an evaluation was conducted. Questionnaires was used to gather response from the users. The evaluations ascertained that the model developed is flexible and adaptable to the different working modes, and the system is capable of supporting several different models of the software inspection process.

Investigation of neural correlates of faces and emotional expressions using magnetoencephalography

The recognition of faces and of facial expressions in an important evolutionary skill, and an integral part of social communication. It has been argued that the processing of faces is distinct from the processing of non-face stimuli and functional neuroimaging investigations have even found evidence of a distinction between the perception of faces and of emotional expressions. Structural and temporal correlates of face perception and facial affect have only been separately identified. Investigation neural dynamics of face perception per se as well as facial affect would allow the mapping of these in space, time and frequency specific domains. Participants were asked to perform face categorisation and emotional discrimination tasks and Magnetoencephalography (MEG) was used to measure the neurophysiology of face and facial emotion processing. SAM analysis techniques enable the investigation of spectral changes within specific time-windows and frequency bands, thus allowing the identification of stimulus specific regions of cortical power changes. Furthermore, MEG’s excellent temporal resolution allows for the detection of subtle changes associated with the processing of face and non-face stimuli and different emotional expressions. The data presented reveal that face perception is associated with spectral power changes within a distributed cortical network comprising occipito-temporal as well as parietal and frontal areas. For the perception of facial affect, spectral power changes were also observed within frontal and limbic areas including the parahippocampal gyrus and the amygdala. Analyses of temporal correlates also reveal a distinction between the processing of faces and facial affect. Face perception per se occurred at earlier latencies whereas the discrimination of facial expression occurred within a longer time-window. In addition, the processing of faces and facial affect was differentially associated with changes in cortical oscillatory power for alpha, beta and gamma frequencies. The perception of faces and facial affect is associated with distinct changes in cortical oscillatory activity that can be mapped to specific neural structures, specific time-windows and latencies as well as specific frequency bands. Therefore, the work presented in this thesis provides further insight into the sequential processing of faces and facial affect.

Temporal finite elements in the dynamic analysis of structures

This thesis demonstrates that the use of finite elements need not be confined to space alone, but that they may also be used in the time domain, It is shown that finite element methods may be used successfully to obtain the response of systems to applied forces, including, for example, the accelerations in a tall structure subjected to an earthquake shock. It is further demonstrated that at least one of these methods may be considered to be a practical alternative to more usual methods of solution. A detailed investigation of the accuracy and stability of finite element solutions is included, and methods of applications to both single- and multi-degree of freedom systems are described. Solutions using two different temporal finite elements are compared with those obtained by conventional methods, and a comparison of computation times for the different methods is given. The application of finite element methods to distributed systems is described, using both separate discretizations in space and time, and a combined space-time discretization. The inclusion of both viscous and hysteretic damping is shown to add little to the difficulty of the solution. Temporal finite elements are also seen to be of considerable interest when applied to non-linear systems, both when the system parameters are time-dependent and also when they are functions of displacement. Solutions are given for many different examples, and the computer programs used for the finite element methods are included in an Appendix.

Cross-orientation masking is speed invariant between ocular pathways but speed dependent within them

In human (D. H. Baker, T. S. Meese, & R. J. Summers, 2007b) and in cat (B. Li, M. R. Peterson, J. K. Thompson, T. Duong, & R. D. Freeman, 2005; F. Sengpiel & V. Vorobyov, 2005) there are at least two routes to cross-orientation suppression (XOS): a broadband, non-adaptable, monocular (within-eye) pathway and a more narrowband, adaptable interocular (between the eyes) pathway. We further characterized these two routes psychophysically by measuring the weight of suppression across spatio-temporal frequency for cross-oriented pairs of superimposed flickering Gabor patches. Masking functions were normalized to unmasked detection thresholds and fitted by a two-stage model of contrast gain control (T. S. Meese, M. A. Georgeson, & D. H. Baker, 2006) that was developed to accommodate XOS. The weight of monocular suppression was a power function of the scalar quantity ‘speed’ (temporal-frequency/spatial-frequency). This weight can be expressed as the ratio of non-oriented magno- and parvo-like mechanisms, permitting a fast-acting, early locus, as befits the urgency for action associated with high retinal speeds. In contrast, dichoptic-masking functions superimposed. Overall, this (i) provides further evidence for dissociation between the two forms of XOS in humans, and (ii) indicates that the monocular and interocular varieties of XOS are space/time scale-dependent and scale-invariant, respectively. This suggests an image-processing role for interocular XOS that is tailored to natural image statistics—very different from that of the scale-dependent (speed-dependent) monocular variety.

Concurrent multiscale modelling of atomistic and hydrodynamic processes in liquids

Fluctuations of liquids at the scales where the hydrodynamic and atomistic descriptions overlap are considered. The importance of these fluctuations for atomistic motions is discussed and examples of their accurate modelling with a multi-space-time-scale fluctuating hydrodynamics scheme are provided. To resolve microscopic details of liquid systems, including biomolecular solutions, together with macroscopic fluctuations in space-time, a novel hybrid atomistic-fluctuating hydrodynamics approach is introduced. For a smooth transition between the atomistic and continuum representations, an analogy with two-phase hydrodynamics is used that leads to a strict preservation of macroscopic mass and momentum conservation laws. Examples of numerical implementation of the new hybrid approach for the multiscale simulation of liquid argon in equilibrium conditions are provided. © 2014 The Author(s) Published by the Royal Society.

Timed Transition Automata as Numerical Planning Domain

A general technique for transforming a timed finite state automaton into an equivalent automated planning domain based on a numerical parameter model is introduced. Timed transition automata have many applications in control systems and agents models; they are used to describe sequential processes, where actions are labelling by automaton transitions subject to temporal constraints. The language of timed words accepted by a timed automaton, the possible sequences of system or agent behaviour, can be described in term of an appropriate planning domain encapsulating the timed actions patterns and constraints. The time words recognition problem is then posed as a planning problem where the goal is to reach a final state by a sequence of actions, which corresponds to the timed symbols labeling the automaton transitions. The transformation is proved to be correct and complete and it is space/time linear on the automaton size. Experimental results shows that the performance of the planning domain obtained by transformation is scalable for real world applications. A major advantage of the planning based approach, beside of the solving the parsing problem, is to represent in a single automated reasoning framework problems of plan recognitions, plan synthesis and plan optimisation.

Weakly-constrained codes for suppression of patterning effects in digital communications

We propose weakly-constrained stream and block codes with tunable pattern-dependent statistics and demonstrate that the block code capacity at large block sizes is close to the the prediction obtained from a simple Markov model published earlier. We demonstrate the feasibility of the code by presenting original encoding and decoding algorithms with a complexity log-linear in the block size and with modest table memory requirements. We also show that when such codes are used for mitigation of patterning effects in optical fibre communications, a gain of about 0.5dB is possible under realistic conditions, at the expense of small redundancy 10%). © 2006 IEEE.

Holocene Mg/Ca, alkenones, and light stable isotope measurements on the outer North Iceland shelf, sediment core MD99-2269

We present new Holocene century to millennial-scale proxies for the well-dated piston core MD99-2269 from Húnaflóadjúp on the North Iceland Shelf. The core is located in 365 mwd and lies close to the fluctuating boundary between Atlantic and Arctic/Polar waters. The proxies are: alkenone-based SST°C, and Mg/Ca SST°C estimates and stable d13C and d18O values on planktonic and benthic foraminifera. The data were converted to 60 yr equi-spaced time-series. Significant trends in the data were extracted using Singular Spectrum Analysis and these accounted for between 50% and 70% of the variance. A comparison between these data with previously published climate proxies from MD99-2269 was carried out on a data set which consisted of 14-variable data set covering the interval 400-9200 cal yr BP at 100 yr time steps. This analysis indicated that the 1st two PC axes accounted for 57% of the variability with high loadings clustering primarily into "nutrient" and "temperature" proxies. Clustering on the 100 yr time-series indicated major changes in environment at ~6350 and ~3450 cal yr BP, which define early, mid- and late Holocene climatic intervals. We argue that a pervasive freshwater cap during the early Holocene resulted in warm SST°s, a stratified water column, and a depleted nutrient supply. The loss of the freshwater layer in the mid-Holocene resulted in high carbonate production, and the late Holocene/neoglacial interval was marked by significantly more variable sea surface conditions.

Do discurso da resistência à resistência do discurso: as construções identitárias de Mossoró nos enunciados da literatura de cordel

This study has as objective to investigate the identity constructions of Mossoró, at the statements of the string literature. Having as thread the episode of resistance of the city against the group of Lampião at June the thirteenth of nineteen twenty seven, our study built itself at the statements present in nine strings, produced between the space-time of 1927 and 2007, year that Mossoró celebrated eighty years of the episode. Aware that the theme extrapolated the limits of the means of communication of the time and it became part of the everyday of the people from Mossoró, producing at the collective memory the image of a resistance city at the street’s names, at companies’ names, at radios’ names with the “FM Resistance”, at the discourses of the politicians, at the city hall which name is “Palace of the Resistance”, the central question that guides our investigation congregates the discussion around the dialogical relations done at the statements about the theme in vogue. This bias, the research elected as categories of analysis the concept of social voices and chronology, considering that the different identities are produced according to placements made by the subjects, as well as, by the context of production. Admitted at the area of Applied Linguistics (AL) and its line language and pratic of social the research articulates the theorizations provided from the area of Cultural Studies (especially regarding identity) with the theoretical framework of the bakhitinian Circle (regarding the social-historical conception of language and in its dialogical character). The results indicate that even existing an axiological movement around the representations of Mossoró and of the episode of 1927, the statements of the strings converge to a hegemonic discourse, corroborating with the identity profile of resistance transported over eighty decades