Wireless Networks with Energy Harvesting and Power Transfer: Joint Power and Time Allocation

In this letter, we consider wireless powered communication networks which could operate perpetually, as the base station (BS) broadcasts energy to the multiple energy harvesting (EH) information transmitters. These employ ���harvest then transmit��� mechanism, as they spend all of their energy harvested during the previous BS energy broadcast to transmit the information towards the BS. Assuming time division multiple access (TDMA), we propose a novel transmission scheme for jointly optimal allocation of the BS broadcasting power and time sharing among the wireless nodes, which maximizes the overall network throughput, under the constraint of average transmit power and maximum transmit power at the BS. The proposed scheme significantly outperforms ���state of the art��� schemes that employ only the optimal time allocation. If a single EH transmitter is considered, we generalize the optimal solutions for the case of fixed circuit power consumption, which refers to a much more practical scenario.

Ant��gona: nome de c��digo: a pe��a em um ato de M��rio Sacramento

Sob a influ��ncia da Ant��gona sofocliana, M��rio de Sacramento escreveu uma pe��a hom��nima publicada, isoladamente, em 1959, no vol. XIX, n�� 186 da ���Revista V��rtice���, e inclu��da, no ano seguinte, na tetralogia intitulada Teatro Anat��mico. Nesta pe��a em um ato, a trag��dia hom��nima de S��focles configura-se um recurso metateatral de car��cter cr��tico-reflexivo, em que o di��logo intertextual com o ancestral texto tr��gico promove uma leitura dram��tica do destino infortunado dos sobreviventes de uma fam��lia francesa, v��tima da ocupa����o alem��o, na Segunda Guerra Mundial, que, como os ��ltimos Labd��cidas, confrontam o sofrimento de situa����es-limite, ditadas por conflitos insol��veis da condi����o humana. Neste ��ensaio dram��tico de M��rio de Sacramento, a protagonista �� uma mulher francesa, Ivonne, que no tempo do Maquis, escolhe, como nome de c��digo, ���Ant��gona���. Pretende-se, neste estudo, apresentar uma an��lise da influ��ncia exercida pela Ant��gona sofocliana neste ��ensaio dram��tico��, ao n��vel da caracteriza����o das dramatis personae e do desenvolvimento da a����o, que se sustenta numa reflex��o cr��tica sobre as motiva����es da filha de ��dipo e o sentido tr��gico das suas a����es.

Attenuation of omega mesons in cold nuclear matter

The attenuation of. mesons in cold nuclear matter has been investigated via the time-dependent multiple-scattering Monte Carlo multicollisional (MCMC) intranuclear cascade model. The inelastic. width deduced from CBELSA/TAPS Collaboration data of meson transparency in complex nuclei (Gamma* similar or equal to 30 MeV/c(2)) is approximately 5 times lower than the value obtained with recent theoretical models and consistent with an in-medium total omega N cross section within 25-30 mb for an average meson momentum of 1.1 GeV/c. The momentum-dependent transparency ratios suggest an elastic/total cross-section ratio around 40%. For the case of CLAS Collaboration data a much higher width is deduced (Gamma* greater than or similar to 120 MeV/c(2)), with the MCMC model providing a consistent interpretation of the data, assuming a much higher meson absorption (sigma(omega N)* greater than or similar to 100 mb) for p(omega) similar to 1.7 GeV/c.

A BEM model applied to failure analysis of multi-fractured structures

Due to manufacturing or damage process, brittle materials present a large number of micro-cracks which are randomly distributed. The lifetime of these materials is governed by crack propagation under the applied mechanical and thermal loadings. In order to deal with these kinds of materials, the present work develops a boundary element method (BEM) model allowing for the analysis of multiple random crack propagation in plane structures. The adopted formulation is based on the dual BEM, for which singular and hyper-singular integral equations are used. An iterative scheme to predict the crack growth path and crack length increment is proposed. This scheme enables us to simulate the localization and coalescence phenomena, which are the main contribution of this paper. Considering the fracture mechanics approach, the displacement correlation technique is applied to evaluate the stress intensity factors. The propagation angle and the equivalent stress intensity factor are calculated using the theory of maximum circumferential stress. Examples of multi-fractured domains, loaded up to rupture, are considered to illustrate the applicability of the proposed method. (C) 2011 Elsevier Ltd. All rights reserved.

Different Approaches for Modeling Grouped Survival Data: A Mango Tree Study

Interval-censored survival data, in which the event of interest is not observed exactly but is only known to occur within some time interval, occur very frequently. In some situations, event times might be censored into different, possibly overlapping intervals of variable widths; however, in other situations, information is available for all units at the same observed visit time. In the latter cases, interval-censored data are termed grouped survival data. Here we present alternative approaches for analyzing interval-censored data. We illustrate these techniques using a survival data set involving mango tree lifetimes. This study is an example of grouped survival data.

Kinetic analysis of vascular marker distribution in perfused rat livers after regeneration following partial hepatectomy

Background/Aims: Liver clearance models are based on information (or assumptions) on solute distribution kinetics within the microvasculatory system, The aim was to study albumin distribution kinetics in regenerated livers and in livers of normal adult rats, Methods: A novel mathematical model was used to evaluate the distribution space and the transit time dispersion of albumin in livers following regeneration after a two-thirds hepatectomy compared to livers of normal adult rats. Outflow curves of albumin measured after bolus injection in single-pass perfused rat livers were analyzed by correcting for the influence of catheters and fitting a long-tailed function to the data. Results: The curves were well described by the proposed model. The distribution volume and the transit time dispersion of albumin observed in the partial hepatectomy group were not significantly different from livers of normal adult rats. Conclusions: These findings suggest that the distribution space and the transit time dispersion of albumin (CV2) is relatively constant irrespective of the presence of rapid and extensive repair. This invariance of CV2 implies, as a first approximation, a similar degree of intrasinusoidal mixing, The finding that a sum of two (instead of one) inverse Gaussian densities is an appropriate empirical function to describe the outflow curve of vascular indicators has consequences for an improved prediction of hepatic solute extraction.

Consumo de eletricidade nas fam��lias na Regi��o Aut��noma dos A��ores

Tese de Doutoramento em Ci��ncias Econ��micas e Empresariais, especialidade em Desenvolvimento Regional.

Analysing TDMA with slot skipping

We propose a schedulability analysis for a particular class of time division multiple access (TDMA) networks, which we label as TDMA/SS. SS stands for slot skipping, reflecting the fact that a slot is skipped whenever it is not used. Hence, the next slot can start earlier in benefit of hard real-time traffic. In the proposed schedulability analysis, we assume knowledge of all message streams in the system, and that each node schedules messages in its output queue according to a rate monotonic policy (as an example). We present the analysis in two steps. Firstly, we address the case where a node is only permitted to transmit a maximum of one message per TDMA cycle. Secondly, we generalise the analysis to the case where a node is assigned a budget of messages per TDMA cycle it may transmit. A simple algorithm to assign budgets to nodes is also presented.

Analyzing TDMA with slot skipping

Distributed real-time systems, such as factory automation systems, require that computer nodes communicate with a known and low bound on the communication delay. This can be achieved with traditional time division multiple access (TDMA). But improved flexibility and simpler upgrades are possible through the use of TDMA with slot-skipping (TDMA/SS), meaning that a slot is skipped whenever it is not used and consequently the slot after the skipped slot starts earlier. We propose a schedulability analysis for TDMA/SS. We assume knowledge of all message streams in the system, and that each node schedules messages in its output queue according to deadline monotonic. Firstly, we present a non-exact (but fast) analysis and then, at the cost of computation time, we also present an algorithm that computes exact queuing times.

Exact analysis of TDMA with slot skipping

Consider a communication medium shared among a set of computer nodes; these computer nodes issue messages that are requested to be transmitted and they must finish their transmission before their respective deadlines. TDMA/SS is a protocol that solves this problem; it is a specific type of Time Division Multiple Access (TDMA) where a computer node is allowed to skip its time slot and then this time slot can be used by another computer node. We present an algorithm that computes exact queuing times for TDMA/SS in conjunction with Rate-Monotonic (RM) or Earliest- Deadline-First (EDF).

RealCrono ���sistema de difus��o de resultados em tempo real na web

A velocidade de difus��o de conte��dos numa plataforma web, assume uma elevada relev��ncia em servi��os onde a informa����o se pretende atualizada e em tempo real. Este projeto de Mestrado, apresenta uma abordagem de um sistema distribu��do de recolher e difundir resultados em tempo real entre v��rias plataformas, nomeadamente sistemas m��veis. Neste contexto, tempo real entende-se como uma diferen��a de tempo nula entre a recolha e difus��o, ignorando fatores que n��o podem ser controlados pelo sistema, como lat��ncia de comunica����o e tempo de processamento. Este projeto tem como base uma arquitetura existente de processamento e publica����o de resultados desportivos, que apresentava alguns problemas relacionados com escalabilidade, seguran��a, tempos de entrega de resultados longos e sem integra����o com outras plataformas. Ao longo deste trabalho procurou-se investigar fatores que condicionassem a escalabilidade de uma aplica����o web dando ��nfase �� implementa����o de uma solu����o baseada em replica����o e escalabilidade horizontal. Procurou-se tamb��m apresentar uma solu����o de interoperabilidade entre sistemas e plataformas heterog��neas, mantendo sempre elevados n��veis de performance e promovendo a introdu����o de plataformas m��veis no sistema. De v��rias abordagens existentes para comunica����o em tempo real sobre uma plataforma web, adotou-se um implementa����o baseada em WebSocket que elimina o tempo desperdi��ado entre a recolha de informa����o e sua difus��o. Neste projeto �� descrito o processo de implementa����o da API de recolha de dados (Collector), da biblioteca de comunica����o com o Collector, da aplica����o web (Publisher) e sua API, da biblioteca de comunica����o com o Publisher e por fim a implementa����o da aplica����o m��vel multi-plataforma. Com os componentes criados, avaliaram-se os resultados obtidos com a nova arquitetura de forma a aferir a escalabilidade e performance da solu����o criada e sua adapta����o ao sistema existente.

Therapeutic drug monitoring of imatinib: Bayesian and alternative methods to predict trough levels

Background: The imatinib trough plasma concentration (C(min)) correlates with clinical response in cancer patients. Therapeutic drug monitoring (TDM) of plasma C(min) is therefore suggested. In practice, however, blood sampling for TDM is often not performed at trough. The corresponding measurement is thus only remotely informative about C(min) exposure. Objectives: The objectives of this study were to improve the interpretation of randomly measured concentrations by using a Bayesian approach for the prediction of C(min), incorporating correlation between pharmacokinetic parameters, and to compare the predictive performance of this method with alternative approaches, by comparing predictions with actual measured trough levels, and with predictions obtained by a reference method, respectively. Methods: A Bayesian maximum a posteriori (MAP) estimation method accounting for correlation (MAP-ρ) between pharmacokinetic parameters was developed on the basis of a population pharmacokinetic model, which was validated on external data. Thirty-one paired random and trough levels, observed in gastrointestinal stromal tumour patients, were then used for the evaluation of the Bayesian MAP-ρ method: individual C(min) predictions, derived from single random observations, were compared with actual measured trough levels for assessment of predictive performance (accuracy and precision). The method was also compared with alternative approaches: classical Bayesian MAP estimation assuming uncorrelated pharmacokinetic parameters, linear extrapolation along the typical elimination constant of imatinib, and non-linear mixed-effects modelling (NONMEM) first-order conditional estimation (FOCE) with interaction. Predictions of all methods were finally compared with 'best-possible' predictions obtained by a reference method (NONMEM FOCE, using both random and trough observations for individual C(min) prediction). Results: The developed Bayesian MAP-ρ method accounting for correlation between pharmacokinetic parameters allowed non-biased prediction of imatinib C(min) with a precision of ��30.7%. This predictive performance was similar for the alternative methods that were applied. The range of relative prediction errors was, however, smallest for the Bayesian MAP-ρ method and largest for the linear extrapolation method. When compared with the reference method, predictive performance was comparable for all methods. The time interval between random and trough sampling did not influence the precision of Bayesian MAP-ρ predictions. Conclusion: Clinical interpretation of randomly measured imatinib plasma concentrations can be assisted by Bayesian TDM. Classical Bayesian MAP estimation can be applied even without consideration of the correlation between pharmacokinetic parameters. Individual C(min) predictions are expected to vary less through Bayesian TDM than linear extrapolation. Bayesian TDM could be developed in the future for other targeted anticancer drugs and for the prediction of other pharmacokinetic parameters that have been correlated with clinical outcomes.

A Note on improving Contact Times in Panel Surveys

With increasing costs for conducting surveys, many survey agencies resort to implementing call strategies. Obtaining contact in panel surveys as early as possible, without annoying people by contacting them at undesired times and ultimately causing them to refuse, requires using efficient call time strategies. In this research, the author uses call data from the Swiss Household Panel (SHP), a centralized Computer Assisted Telephone Interview (CATI) survey with a randomized (experimental) call-household assignment. Using random effects models, the author analyzes the efficiency gains of obtaining initial contact by assigning optimal times to first calls, and times and spacing to second and later calls depending on household sociodemography and prior call patterns. The author concludes with some recommendations for making early and successful contact during fieldwork.

A simulation-based algorithm for solving the resource-assignment problem in satellite telecommunication networks

This paper proposes an heuristic for the scheduling of capacity requests and the periodic assignment of radio resources in geostationary (GEO) satellite networks with star topology, using the Demand Assigned Multiple Access (DAMA) protocol in the link layer, and Multi-Frequency Time Division Multiple Access (MF-TDMA) and Adaptive Coding and Modulation (ACM) in the physical layer.