Performance of an Echo Canceller and Channel Estimator for On-Channel Repeaters in DVB-T/H Networks

This paper investigates the design and performance of an FIR echo canceller for on-channel repeaters in DVB-T/H network within the framework of the PLUTO project. The possible approaches for echo cancellation are briefly reviewed and the main guidelines for the design of such systems are presented. The main system parameters are discussed. The performance of an FIR echo canceller based on an open loop feedforward approach for channel estimation is tested for different radio channel conditions and for different number of taps of the FIR filter. It is shown that a minimum number of taps is recommended to achieve a certain mean rejection ratio or isolation depending on the type of channel. The expected degradation in performance due to the use of fixed point rather than floating point arithmetic in hardware implementation is presented for different number of bits. Channel estimation based on training sequences is investigated. The performance of Maximum Length Sequences and Constant Amplitude Zero Autocorrelation (CAZAC) Sequences is compared for different channels. Recommendations are given for training sequence type, length and level for DVB-T/H on-channel repeater deployment

Testing the Mere Exposure Effect in Videogaming

Due to proliferation of media and platforms it is becoming increasingly difficult for marketers to reach and engage consumers using traditional forms of mass media such as advertising. Marketers are turning to alternate forms of communication, such as brand placement in videogames as the games industry continues to grow. To date academic research appears inconclusive in terms of validating the use of videogames as a promotional tool. Moreover, there is a lack of empirical evidence concerning the effects on consumers and brands of marketing messages in the videogame environment. This aim of this study was to investigate whether exposure to brand placement affects unknown brand likeability as a result of mere exposure for game players and game watchers in videogames. The study adopted a quasi-experiment between group design, with a Control, Watch Group and Play Group (300 participants in total) and a post exposure questionnaire. Results suggest some support a mere exposure effect which is that a frequently presented brand placement in a videogame can have a positive effect on players and watchers’ brand attitudes, although they do not recall the brand. This is the first empirical study to investigate brand placement and mere exposure effects in videogames. Theoretically, the study contributes to knowledge concerning brand placement processing in videogames and builds on the existing paradigms of MEE, low-involvement processing, implicit and explicit processing and brand attitude formation. For game developers and brand owners, the study has implications for marketing communications strategy, and graphic design elements for the placements, design of videogames and the most effective position for placements in a game

Mid-Infrared Imaging and Modelling of the Dust Shell around Post-AGB star HD 187885 (IRAS 19500-1709)

We present 10 and 20 micron images of IRAS 19500-1709 taken with the mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. We use a 2-D dust radiation transport code to fit the spectral energy distribution from UV to sub-mm wavelengths and to simulate the images.Comment: 4 pages, 5 figures. To appear in "Asymmetric Planetary Nebulae III", eds. M.Meixner, J.Kastner, N.Soker & B.Balick. 2004, ASP Conference Serie

Particle simulation of plasmas on the massively parallel processor

Particle simulations, in which collective phenomena in plasmas are studied by following the self consistent motions of many discrete particles, involve several highly repetitive sets of calculations that are readily adaptable to SIMD parallel processing. A fully electromagnetic, relativistic plasma simulation for the massively parallel processor is described. The particle motions are followed in 2 1/2 dimensions on a 128 x 128 grid, with periodic boundary conditions. The two dimensional simulation space is mapped directly onto the processor network; a Fast Fourier Transform is used to solve the field equations. Particle data are stored according to an Eulerian scheme, i.e., the information associated with each particle is moved from one local memory to another as the particle moves across the spatial grid. The method is applied to the study of the nonlinear development of the whistler instability in a magnetospheric plasma model, with an anisotropic electron temperature. The wave distribution function is included as a new diagnostic to allow simulation results to be compared with satellite observations

Optimization of Multidimensional Nuclear Magnetic Resonance Spectroscopy, for Resolution and Sensitivity, Through Application of Radial Sampling

The high probability of degenerate frequencies in NMR spectra of complex biopolymers such as proteins presented a great barrier to detailed analysis. The combination of multidimensional NMR spectroscopy and high magnetic field strengths has overcome the resulting resonance assignment problem for proteins less than 50 kDa. However, as protein size increases the sampling and sensitivity limited regimes become apparent. As a consequence, the orthogonal linear sampling requirements of conventional multidimensional NMR spectroscopy, combined with increased signal averaging require a longer acquisition time than is feasible. To overcome these limitations, radial sampling of the indirect dimensions of multidimensional experiments is utilized. It is demonstrated here, that through optimization of radial sampling acquisition parameters, it is possible to escape the linear sequential sampling requirements of Cartesian sampling, which allows for the collection of a high resolution spectrum in reduced acquisition time. Further, by exploiting a fundamental statistical advantage of radial sampling, it is possible to obtain a signal-to-noise advantage, over the traditional methodology. The approach is generalized by developing an all inclusive NMR data processing package and associated programs to optimize radial sampling acquisition parameters. An example, which utilizes the resolution and sensitivity advantages, to collect a novel application of a high resolution four-dimensional 13C, 15N edited NOESY is presented in support

High Quality, Transferable Graphene Grown on Single Crystal Cu(111) Thin Films on Basal-Plane Sapphire

The current method of growing large-area graphene on Cu surfaces (polycrystalline foils and thin films) and its transfer to arbitrary substrates is technologically attractive. However, the quality of graphene can be improved significantly by growing it on single-crystal Cu surfaces. Here we show that high quality, large-area graphene can be grown on epitaxial single-crystal Cu(111) thin films on reusable basal-plane sapphire (alpha-Al2O3(0001)) substrates and then transferred to another substrate. While enabling graphene growth on Cu single-crystal surfaces, this method has the potential to avoid the high cost and extensive damage to graphene associated with sacrificing bulk single-crystal Cu during graphene transfer.Comment: 10 pages, 3 figure

Exploring the Iron‐Binding Potential of the Ocean Using a Combined pH and DOC Parameterization

The major part of dissolved iron (DFe) in seawater is bound to organic matter, which prevents iron from adsorptive removal by sinking particles and essentially regulates the residence time of DFe and its availability for marine biota. Characteristics of iron‐binding ligands highly depend on their biological origin and physico‐chemical properties of seawater which may intensely alter under ongoing climate change. To understand environmental controls on the iron binding, we applied a function of pH and dissolved organic carbon (DOC) to describe changes in the binding strength of organic ligands in a global biogeochemical model (REcoM). This function was derived based on calculations using a thermodynamic chemical speciation model NICA. This parameterization considerably improved the modeled DFe distribution, particularly in the surface Pacific and the global mesopelagic and deep waters, compared to our previous model simulations with a constant ligand or one prognostic ligand. This indicates that the organic binding of iron is apparently controlled by seawater pH in addition to its link to organic matter. We tested further the response of this control to environmental changes in a simulation with future pH of a high emission scenario. The response of the binding potential shows a complex pattern in different regions and is regulated by factors that have opposite effects on the binding potential. The relative contributions of these factors can change over time by a continual change of environmental conditions. A dynamic feedback system therefore needs to be considered to predict the marine iron cycle under ongoing climate change