A Methodology to Design FPGA-based PID Controllers

This paper presents a methodology to implement PID (Proportional, Integral, Derivative) controllers in FPGAs (Field-Programmable Gate Arrays) using fixed-point numerical representation. The Matlab/Simulink environment is used for modeling, simulation and evaluation the performance provided by different fixed-point representations using a given control process. A static bit-width analyzer is used to give a specialized fixed-point representation for each operand/operator in the controller system. After bit-width analysis, a VHDL represen-tation of the system is generated. Results show that the proposed methodology leads to shorten design cycles achieving important resource savings by employing specialized fixed-point repre-sentations

Dimensionamento de estruturas de alvenaria sujeita a acções sísmicas

Com o presente trabalho apresentam-se aspectos relacionados com o dimensionamento de estruturas de alvenaria sujeitas a acções sísmicas. São referidas exigências materiais e de cálculo de estruturas de alvenaria especificadas no Eurocódigo 6 e no Eurocódigo 8. Aborda-se o dimensionamento à acção sísmica segundo os referidos eurocódigos. Apresenta-se uma discussão da formulação de cálculo sísmico de três softwares existentes no mercado para o dimensionamento de estruturas de alvenaria, e efectua-se uma comparação da aceleração sísmica obtida pelos diferentes programas e através de um cálculo manual para um edifício-exemplo

Automatic Vehicle Trajectory Extraction by Aerial Remote Sensing

Research in road users’ behaviour typically depends on detailed observational data availability, particularly if the interest is in driving behaviour modelling. Among this type of data, vehicle trajectories are an important source of information for traffic flow theory, driving behaviour modelling, innovation in traffic management and safety and environmental studies. Recent developments in sensing technologies and image processing algorithms reduced the resources (time and costs) required for detailed traffic data collection, promoting the feasibility of site-based and vehicle-based naturalistic driving observation. For testing the core models of a traffic microsimulation application for safety assessment, vehicle trajectories were collected by remote sensing on a typical Portuguese suburban motorway. Multiple short flights over a stretch of an urban motorway allowed for the collection of several partial vehicle trajectories. In this paper the technical details of each step of the methodology used is presented: image collection, image processing, vehicle identification and vehicle tracking. To collect the images, a high-resolution camera was mounted on an aircraft's gyroscopic platform. The camera was connected to a DGPS for extraction of the camera position and allowed the collection of high resolution images at a low frame rate of 2s. After generic image orthorrectification using the flight details and the terrain model, computer vision techniques were used for fine rectification: the scale-invariant feature transform algorithm was used for detection and description of image features, and the random sample consensus algorithm for feature matching. Vehicle detection was carried out by median-based background subtraction. After the computation of the detected foreground and the shadow detection using a spectral ratio technique, region segmentation was used to identify candidates for vehicle positions. Finally, vehicles were tracked using a k- shortest disjoints paths algorithm. This approach allows for the optimization of an entire set of trajectories against all possible position candidates using motion-based optimization. Besides the importance of a new trajectory dataset that allows the development of new behavioural models and the validation of existing ones, this paper also describes the application of state-of-the-art algorithms and methods that significantly minimize the resources needed for such data collection. Keywords: Vehicle trajectories extraction, Driver behaviour, Remote sensin

Mobile laboratories as an alternative to conventional remote laboratories

Remote laboratories have been playing an important role on the improvement of flexibility and the extent of practical activities in teaching and learning activities in engineering and technology. However, the current remote laboratories model does not consider dynamic scenarios including collaboration, peer-to-peer labs and mobile labs. This paper presents a set of tools for creating collaborative online mobile laboratories that allow students to develop their own labs and share them with classmates and teachers. The approach used is compatible with the machine and network configurations that the target user has in schools and at home, and provides the retrieval of information for learning evaluation.info:eu-repo/semantics/publishedVersio

Estimating sheet flow velocities using quinine as a fluorescent tracer: bare, mulched, vegetated and paved surfaces

When direct flow velocity measurements are not feasible, the use of tracers can be a valuable tool. In the present study, both laboratory and field experiments were conducted to evaluate the applicability of quinine as a fluorescent tracer for estimating mean sheet flow velocities in different ambient light and surface morphology conditions. Quinine excels in low-light conditions when exposed to UVA light. This tracer was compared with dye and thermal tracers, all in liquid form. In these tracing techniques the tracers were injected into the flow, after which surface velocity was estimated by tracking the leading edge of the tracer plumes and applying a correction factor to calculate the mean velocity (in a water column). The visibility of the tracers was evaluated by measuring the relative luminance and contrast ratio of the quinine and dye tracer plumes. Results show that the quinine tracer can be used to estimate sheet flow velocities over a wide variety of soil and urban surfaces; it has better visibility in comparison to the dye tracer but, in some conditions, lower visibility than the thermal tracer. Although quinine is invisible under bright ambient light conditions, this tracer technique requires low-cost experimental setup and is useful in low-light conditions (e.g., night; twilight; shielded environments).info:eu-repo/semantics/publishedVersio

DNA repair genes polymorphisms and genetic susceptibility to Philadelphia-negative myeloproliferative neoplasms in a Portuguese population: the role of base excision repair genes polymorphisms

Sob uma licença CC-BY-NC-ND - http://creativecommons.org/licenses/by-nc-nd/4.0/The role of base excision repair (BER) genes in Philadelphia-negative (PN)-myeloproliferative neoplasms (MPNs) susceptibility was evaluated by genotyping eight polymorphisms [apurinic/apyrimidinic endodeoxyribonuclease 1, mutY DNA glycosylase, earlier mutY homolog (E. coli) (MUTYH), 8‑oxoguanine DNA glycosylase 1, poly (ADP‑ribose) polymerase (PARP) 1, PARP4 and X‑ray repair cross‑complementing 1 (XRCC1)] in a case‑control study involving 133 Caucasian Portuguese patients. The results did not reveal a correlation between individual BER polymorphisms and PN‑MPNs when considered as a whole. However, stratification for essential thrombocythaemia revealed i) borderline effect/tendency to increased risk when carrying at least one variant allele for XRCC1_399 single‑nucleotide polymorphism (SNP); ii) decreased risk for Janus kinase 2‑positive patients carrying at least one variant allele for XRCC1_399 SNP; and iii) decreased risk in females carrying at least one variant allele for MUTYH SNP. Combination of alleles demonstrated an increased risk to PN‑MPNs for one specific haplogroup. These findings may provide evidence for gene variants in susceptibility to MPNs. Indeed, common variants in DNA repair genes may hamper the capacity to repair DNA, thus increasing cancer susceptibility.info:eu-repo/semantics/publishedVersio

Sediment transport rate-based model for rainfall-induced soil erosion

http://www.sciencedirect.com/science/article/B6VCG-4TP7HC2-1/2/2a6275ceb0176f80cedfb5efe5ef248