On Adaptive Density Deployment to Mitigate the Sink-Hole Problem in Mobile Sensor Networks

The use of mobile sensors is of great relevance to monitor critical areas where sensors cannot be deployed manually. The presence of data collector sinks causes increased energy depletion in their proximity, due to the higher relay load under multi-hop communication schemes (sink-hole phenomenon). We propose a new approach towards the solution of this problem by means of an autonomous deployment algorithm that guarantees the adaptation of the sensor density to the sink proximity and enables their selective activation. The proposed algorithm also permits a fault tolerant and self-healing deployment, and allows the realization of an integrated solution for deployment, dynamic relocation and selective sensor activation. We formally prove the termination of our algorithm. Performance comparisons between our proposal and previous approaches show how the former can efficiently reach a deployment at the desired variable density with moderate energy consumption under a wide range of operative settings.     

Electrode surface treatments in sludge electro-osmosis dewatering

The sewage sludge dewatering produced by wastewater treatment plants (WWTP) is a multifaceted process due to the presence of colloid fractions. Electro-osmosis could be a suitable technique to reduce the water content of the final sludge. Electric fields of 10, 15, and 20?V/cm have been studied for electro-osmosis tests under the pressure of a static or rotating piston, obtaining a dry solids content up to 40–45%, with respect to 25–30% obtained by mechanical methods. In order to optimize the process, the corrosion behavior and the wear of the anodic material appear to be the main critical aspects, due to the high circulating current density and the use of a rotating electrode. We compared the efficiency and the corrosion resistance of dimensionally stable anodes (DSA) with respect to bare stainless steel (AISI 304) and stainless steel coated by PVD technique with TiN, AlTiN, and DLC. Characterization of the anode surfaces by SEM and potentiodynamic tests show that DSA is the most suitable material for our application. However, efficiencies of the electro-osmosis processes have been found comparable, in terms of developed current densities and total energy consumptions, for short-test duration.     

Mapping the development of Open Access in Latin America and Caribbean countries. An analysis of Web of Science Core Collection and SciELO Citation Index (2005–2017)

Scientometrics - Open Access (OA) initiatives and knowledge infrastructure represent vital elements for both producing significant changes in scholarly communication and reducing limitations of...     

Optimal packing of material flow on conveyor belts

We are interested in an optimal packing density problem for material flows on conveyor belts in two spatial dimensions. The control problem is concerned with the initial configuration of parts on the belt to ensure a high overall flow rate and to further reduce congestion. An adjoint approach is used to compare the optimization results from the microscopic model based on a system of ordinary differential equations with the corresponding macroscopic model relying on a hyperbolic conservation law. Computational results highlight similarities and differences of both optimization models and emphasize the benefits of the macroscopic approach.     

A GC-EI-MS/MS Method for the Determination of 15 Polybrominated Diphenyl Ethers (PBDEs) in Fish and Shellfish Tissues

This paper describes the development and validation of an analytical method to determine 15 polybrominated diphenyl ethers (PBDEs) in fish and shellfish tissues with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS). A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)-like procedure was applied; the extract was cleaned up on an acidic Extrelut-NT3 column connected on top of a silica cartridge and further purified with gel permeation chromatography (GPC). The SIM acquisition proved to yield better results than traditional MRM approach for octa-, nona-, and deca-brominated congeners. The validation study was carried out in inter-laboratory conditions. The average recoveries were in the range 66–118%, with relative standard deviations generally lower than or equal to 22%. Quality assurance and quality control practices were thoroughly described and highlighted. These long and tedious practices are fundamental to obtain reliable quantitative data during food monitoring programs and, therefore, to support daily intake assessments. Finally, the procedure was applied to the analysis of marine fish samples collected in local markets. Mackerel and mullet were the most contaminated species.     

Property specification patterns at work: verification and inconsistency explanation

Innovations in Systems and Software Engineering - Property specification patterns (PSPs) have been proposed to ease the formalization of requirements, yet enable automated verification thereof. In...     

Proteomics in the Diagnosis of Endometriosis: Opportunities and Challenges

The non‐surgical diagnosis of endometriosis is still challenging for the clinician. Ultrasonography and magnetic resonance imaging can be used to diagnose ovarian endometriotic cysts and deep infiltrating endometriosis; but their performance is poor in the diagnosis of initial stages of endometriosis. CA‐125 and other serum markers (such as CA 19‐9, serum protein PP14, interleukins, and angiogenetic factors) have been measured in women with endometriosis but they are not reliable for the diagnosis of the disease. Although several studies used proteomics technologies to identify plasmatic markers of endometriosis, the non‐invasive diagnosis of endometriosis is far from being achieved. In this issue, Manousopoulou et al. compare the integrated quantitative proteomic profile of eutopic endometrium and serum of women with endometriosis and controls. 1214 proteins are differentially expressed in the eutopic endometrium and 404 proteins in the serum of the two study groups. 21 proteins are aberrantly expressed in both eutopic endometrium and serum of women with endometriosis. More work is needed to assess if the differentially expressed proteins identified in this study can be used as clinical markers of endometriosis.     

Infrastructure,automation and model-based operation strategy in a stand-alone hydrolytic solar-hydrogen production unit

An autonomous power system that exploits solar energy for the production of hydrogen through water electrolysis is fully assessed in terms of system implementation and optimal operating strategy. A 10 kW_p photovoltaic array supplies energy to a PEM electrolyzer rated at 6.9 kW_p. In order to maintain a smooth operation regardless of the inherent weather fluctuations, a 1000 Ah/24 V lead–acid accumulator stores energy excess and provides it when needed. The monitoring and control of the system is implemented through a Supervisory Control and Data Acquisition system (SCADA), while the interactions between electrical and chemical subsystems are addressed by a complete automation infrastructure. The mathematical models of each subsystem are validated based on real operational data and a model-based power management strategy is proposed and assessed through a parameter sensitivity analysis. Further on, an off-line optimization framework is evaluated regarding the optimal operation of the system in two diverse, but representative time periods. The optimal parameters are identified and their effect on hydrogen production and accumulator utilization is reported.     

Pressure drop during air flow in aluminum foams

This paper aims at investigating experimentally the pressure drop during air flow in six different aluminum open-cell foam samples with different number of pores per inch (PPI) and different porosity under a wide range of air mass flow rate. Three imposed heat fluxes are considered for each foam sample. The collected pressure drop data are analysed with reference to models available in the literature. A new simple pressure drop model, based on present data, has then been developed. The consistency of the proposed model is finally checked by comparison to data available in the literature from different laboratories.