Sampling-sensitive multiresolution hierarchy for irregular meshes

Previous approaches of constructing multiresolution hierarchy for irregular meshes investigated how to overcome the connectivity and topology constraints during the decomposition, but did not consider the effects of sampling information on editing and signal processing operations. We propose a sampling-sensitive downsampling strategy and design a decomposition framework that produces a hierarchy of meshes with decreasing maximum sampling rates and increasingly regular vertex support sizes. The resulting mesh hierarchy has good quality triangles and enables more stable editing. The detail vectors better approximate the frequency spectrum of the mesh, thus making signal filtering more accurate.     

A sliding mode control proposal for open-loop unstable processes

This papers presents a sliding mode controller based on a first-order-plus-dead-time model of the process for controlling open-loop unstable systems. The proposed controller has a simple and fixed structure with a set of tuning equations as a function of the desired performance. Both linear and nonlinear models were used to study the controller performance by computer simulations.     

Development and validation of a high-performance liquid chromatography-mass spectrometry assay for determination of amphetamine, methamphetamine, and methylenedioxy derivatives in meconium

A procedure based on liquid chromatography-mass spectrometry (LC-MS) is described for determination of amphetamine, methamphetamine, and methylendioxy derivatives in meconium, using 3,4-methylendioxypropylamphetamine as internal standard. The analytes were initially extracted from the matrix by 17 mM methanolic HCl. Subsequently, a solid-phase extraction with Bondelut Certify columns was applied. Chromatography was performed on a C(18) reversed-phase column using a linear gradient of 10 mM ammonium bicarbonate, pH 9.0-methanol as a mobile phase. Analytes were determined in LC-MS single ion monitoring mode with an atmospheric pressure ionization-electrospray interface. The method was validated in the range 0.005-1.00 microg/g using 1 g of meconium per assay. Mean recoveries ranged between 61.1 and 87.2% for different analytes. The quantification limits were 0.005 microg/g meconium for amphetamine, methamphetamine, and 4-hydroxy-3-methoxymethamphetamine and 0.004 microg/g meconium for 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyethylamphetamine, and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine. The method was applied to analysis of meconium in newborns to assess eventual fetal exposure to amphetamine derivatives.     

Continuous hyperspectral absorption measurements of colored dissolved organic material in aquatic systems

The majority of organic carbon in the oceans is present as dissolved organic matter (DOM); therefore understanding the distribution and dynamics of DOM is central to understanding global carbon cycles. Describing the time-space variability in colored dissolved organic matter (CDOM) has been difficult, as standard spectrophotometric methods for CDOM determination are laborious and susceptible to methodological biases. Previously, measurements of CDOM absorption in discrete water samples by use of a liquid-waveguide capillary cell (LWCC) compared favorably with measurements made with a benchtop spectrophotometer. Given this, we focused on automating the LWCC technique to improve our spatial and temporal sampling capabilities for CDOM. We found strong correlations between CDOM absorption spectra collected from discrete water samples using standard methods and selected corresponding CDOM spectra collected by the automated LWCC system. The near-continuous measurements by the LWCC system made it possible to map the temporal, spatial, and spectral variability of CDOM absorption along the ship track.     

Identification of protein ligands in complex biological samples using intensity-fading MALDI-TOF mass spectrometry

The easy detection of biomolecular interactions in complex mixtures using a minimum amount of material is of prime interest in molecular and cellular biology research. In this work, a mass spectrometry MALDI-TOF based approach, which we call intensity-fading (IF MALDI-TOFMS), and which was designed for just such a purpose, is reported. This methodology is based on the use of the MALDI ion intensities to detect quickly the formation of complexes between nonimmobilized biomolecules in which a protein is one of the partners (protein-protein, protein-peptide, protein-organic molecule, and protein-nucleic acid complexes). The complex is detected through the decrease (fading) of the molecular ion intensities of the partners as directly compared to the MALDI mass spectrum of the mixture (problem and control molecules) following the addition of the target molecule. The potential of the approach is examined in several examples of model interactions, mainly involving small nonprotein and protein inhibitors of proteases, at both the qualitative and semiquantitative levels. Using this method, different protein ligands of proteolytic enzymes in total extracts of invertebrate organisms have been identified in a simple way. The proposed procedure should be easily applied to the high-throughput screening of biomolecules, opening a new experimental strategy in functional proteomics.     

Bilinear Control for Three-Phase Microgrids: A Proportional-Integral Passivity-Based Design

Abstract

A bilinear PI control based on passivity theory for the adequate integration of distributed energy resources (DERs) in ac microgrids is presented in this paper. DERs are integrated into the grid by voltage source converters (VSC), the most common and suitable technology for this type of application. The proposed control guarantees asymptotically stable operation for the dynamical system under closed-loop operating scenarios via Hamiltonian and Lyapunov formulations. ZP load models and π-model of the transmission lines are considered in the stability analysis of the microgrid. Conventional PI control is also implemented for comparative purposes. Simulation results in Matlab/Simulink demonstrate the effectiveness and stability of the proposed control’s performance in a radial microgrid composed of a photovoltaic generator, a supercapacitor energy storage (SCES) system and unbalanced loads.     

A ROBUST TERMINAL SLIDING COMPOSITE ADAPTIVE CONTROL SCHEME FOR RIGID ROBOTS

In this article is presented a robust adaptive control scheme for mechanical manipulators with finite error convergence time. The design combines, on the one hand, a composite adaptive controller that implements a feedback linearization control law that compensates the modelled dynamics, and, on the other hand, a terminal sliding mode control law that overcomes the uncertainties usually present in the real systems. Then, to avoid the chattering phenomenon inherent to the sliding schemes, the control law is also smoothed out. It is proved that the resulting closed loop system is stable and that the trajectory-tracking error converges to zero in finite time. Moreover, an upper bound of this error convergence time is calculated. Finally, the design is evaluated by means of simulations.     

A GRASP with path-relinking heuristic for the survivable IP/MPLS-over-WSON multi-layer network optimization problem

In this paper we deal with the survivable internet protocol (IP)/multi-protocol label switching (MPLS)-over-wavelength switched optical network (WSON) multi-layer network optimization problem (SIMNO). This problem entails planning an IP/MPLS network layer over a photonic mesh infrastructure whilst, at the same time, ensuring the highest availability of services and minimizing the capital expenditures (CAPEX) investments. Such a problem is currently identified as an open issue among network operators, and hence, its solution is of great interest. To tackle SIMNO, we first provide an integer linear programming (ILP) formulation which provides an insight into the complexity of its managing. Then, a greedy randomized adaptive search procedure (GRASP) with path-relinking (PR) together with a biased random-key genetic algorithm (BRKGA) are specifically developed to help solve the problem. The performance of both heuristics is exhaustively tested and compared making use of various network and traffic instances. Numerical experiments show the benefits of using GRASP instead of BRKGA when dealing with highly complex network scenarios. Moreover, we verified that the use of GRASP with PR remarkably improves the basic GRASP algorithm, particularly in real-sized, complex scenarios such as those proposed in this paper.     

A cognitive-behavioral model of problematic online gaming in adolescents aged 12–22 years

The aim of this study was to apply the cognitive behavioral model of problematic Internet use to the context of online game use to obtain a better understanding of problematic use of online games and its negative consequences. In total, 597 online game playing adolescents aged 12–22 years participated in this study. Results showed that the cognitive behavioral model of problematic Internet use can also be used in the context of online game use. More specifically, preference for online social interaction, mood regulation and deficient self-regulation appeared to play an important role in predicting negative outcomes from problematic online game use. Together, these cognitions and behaviors explained 79% of the variance of negative outcomes scores. These findings can be used to develop strategies that aim at reducing problematic online game behavior and its negative consequences.