Control of Scour at Bridge Piers by a Downstream Bed Sill

Results are presented from laboratory experiments to investigate the effectiveness of bed sills as countermeasures against local scouring at a smooth circular bridge pier, for flow conditions near the threshold of uniform sediment motion. The bed sill was located downstream of the pier, and its effectiveness with the distance between pier and sill was evaluated. The dependence of the scour depth on different dimensionless groups was defined. The results showed that a bed sill placed at a short distance downstream of the pier reduces the scour depth, area, and volume. In particular, the smaller the distance between the two structures, the larger the effectiveness of the countermeasure. The bed sill seems to take effect some time after the beginning of the test, as the scour hole downstream of the bridge pier develops sufficiently and interacts with the countermeasure.     

Calibration transfer for solving the signal instability in quantitative headspace-mass spectrometry

It is reported that calibration transfer is able to compensate the variations in sensitivity in direct coupling of a headspace sampler to a mass spectrometer when used for quantification purposes using multivariate calibration techniques. This strategy of signal stability compensation allows the use of models constructed from large calibration standard sets without having to repeat their measurement even though variations occur in sensitivity, which may or may not be constant along the mass range. This technique offers advantages over the use of internal standards in this methodology and only requires the measurement of a small number of transfer samples with each set of unknown samples. The results obtained in the determination of six volatile organic compounds-benzene, toluene, ethylbenzene, and m-xylene (BTEX), methyl tert-butyl ether (MTBE), and mesitylene-are reported. To obtain an appropriate calibration set, a Plackett-Burman design with five levels of concentration for each component was employed. A PLS multivariate calibration model was constructed with a group of 25 samples. For selection of the optimum number of principal components, an external validation set (5 samples) was used and the prediction capacity of this set was checked with an additional group of samples that had not been used either in the construction or in the validation of the model. The results obtained can be considered highly satisfactory, and the methodology was successfully tested with natural matrixes (river and tap water).     

Hematocrit measurement by dielectric spectroscopy

Based on permittivity changes, a new method to measure hematocrit (HCT) in extracorporeal blood systems is presented. Human blood samples were tested at different HCT levels pairing the values of permittivity change, obtained by means of a commercial impedance analyzer, with traditional centrifugation measurements. Data were correlated using both linear and nonlinear regression. When using the lineal model, the comparison yielded a high correlation coefficient (r = 0.99). Theoretical simplifications suggest that the method is independent of changes in the conductivities of the intracellular and extracellular compartments. The influence of osmolarity and conductivity of the extracellular compartment was analyzed. It is shown that HCT can be predicted within an error lower than 5% when those parameters changed as much as 1 mS/cm and 50 mOsm/kg, respectively. Thus, the method appears as valid and viable showing good possibilities in applications such as renal dialysis.     

Limitation of the achievable signal-to-noise ratio in optical coherence tomography due to mismatch of the balanced receiver

Owing to the limited spectral response of the fiber directional coupler used in a balanced optical coherence tomography configuration, the spectra are different in the two outputs. This affects unfavorably operation of the balanced photodetector unit. Excess photon noise makes a larger contribution than a directional coupler with a flat spectral response. A theoretical model is developed that shows that an optimum set of parameters may be defined to maximize the achievable signal-to-noise ratio. The model leads to a redefinition of the effective noise bandwidth, which takes into account the nonflat response of the directional coupler used. The model also predicts a limitation on the signal-to-noise ratio even when the stray reflectances in the interferometer are brought to zero.     

Automatic Tuning Architecture for the Navigation Control Loops of Unmanned Aerial Vehicles

One of the most time consuming phases in the development of an Unmanned Aerial Vehicle is the tuning of the control algorithms. In this paper the hardware and software suite developed for the self-tuning of the control loops of unmanned flying platforms is presented. The VOLCAN UAV has been used as platform to test and validate the developed architecture. The simplified control system of the VOLCAN UAV is described, together with the Graphical User Interface that allows the rapid automatic tuning of the system by means of Åström and Hägglund’s method. The Hardware in the Loop architecture used to test both the control algorithms and the tuning procedure is presented in the final part of the paper, together with the obtained experimental results.     

Novel strategies for sparse regenerator placement in translucent optical networks

In this paper, we propose two strategies for sparse regenerator placement (RP) in translucent optical networks, named most used regenerator placement (MU-RP), and most simultaneous used regenerator placement (MSU-RP). Our proposals are compared to well known RP algorithms presented in literature for two different network topologies for different network loads, distribution of load along the networks and number of translucent nodes. MSU-RP presented remarkable results and outperformed all previous approaches in all cases, while MSU-RP obtained a slightly superior or similar performance when compared to previous approaches presented in the literature.     

Ivermectin residues in milk of lactating donkey (Equus asinus): current regulation and challenges for the future

Ivermectin (IVM) is a macrocyclic disaccharide anthelmintic agent with broad-spectrum antiparasitic action. It is used for controlling internal and external parasites in food-producing animals (bovine, swine and equine species), including donkey. This drug is included in Council Regulation (EEC) 2377/90, annex I, with Maximum Residue Limit (MRL) ranging from 15 to 100???g?kg^?1 depending on the species. The pharmacokinetic characteristics of IVM mainly depend on the animal species, formulation and route of administration. Due to its high lipophilicity it accumulates in milk of food producing animals. Detailed IVM pharmacokinetic studies were carried out for horse, pig, cattle, sheep, and goat, but there is lack of information for asinine species. Consequently, the absence of ??label milk withdrawal time?? and MRLs in donkey??s milk indicates that IVM should not be used in lactating animals. On the contrary, information about IVM residues in milk would be of paramount importance in view of the fact that donkey??s milk is a suggested substitute for infants suffering from hypersensitivity to cow??s, sheep??s and goat??s milk protein or from multiple hypersensitivity. European legislation does not explicitly state that an MRL should be determined for every target species; however it??s interpretation led to MRLs being adopted for each species and each foodstuff. Although IVM is approved for use in all lactating animal species the possibility of an illegal use should be considered. In this paper, the problems arising from IVM administration in lactating donkey are analysed. A particular attention is paid for the existing legislation and some proposals are suggested for regulatory framework formulation.     

Functional check test for high-speed milling centres of up to five axes

This paper offers a system for checking three or five axes high-speed machining centres by milling a sample sphere pattern. Using the right choice of toolpath, it is possible to check and compare the performance which the centre is capable of following. The main features under study here are ease of use and the great amount of information that can be drawn regarding high-speed machine performances, including the geometrical precision of the machine and tool setup for the chosen machining conditions.     

Coverage Path Planning for UAVs Photogrammetry with Energy and Resolution Constraints

Unmanned Aerial Vehicles (UAVs) are starting to be used for photogrammetric sensing of large areas in several application domains, such as agriculture, rescuing, and surveillance. In this context, the problem of finding a path that covers the entire area of interest is known as Coverage Path Planning (CPP). Although this problem has been addressed by several authors from a geometrical point of view, other issues such as energy, speed, acceleration, and image resolution are not often taken into account. To fill this gap, this paper first proposes an energy model derived from real measurements, and then uses this model to implement a coverage path planning algorithm for reducing energy consumption, as well as guaranteeing a desired image resolution. In addition, two safety mechanisms are presented: the first, executed off-line, checks whether the energy stored in the battery is sufficient to perform the planned path; the second, performed online, triggers a safe return-to-launch (RTL) operation when the actual available energy is equal to the energy required by the UAV to go back to the starting point.