Robust control of wind turbines based on fractional nonlinear disturbance observer

In order to assure maximum energy conversion, the angular velocity of the wind turbine rotor tracks a nominal profile depending on the wind speed. However, conventionally, wind flows present non‐differentiable components due to turbulence and gust winds, which affect the wind energy management. Thus, a fast and robust controller is required to induce such nominal regime for maximum energy transfer. A fractional‐order nonlinear disturbance‐observer (FNDOB) is proposed in this paper to cancel the non‐differentiable components of the wind speed, as well as dynamic uncertainties and other aerodynamic disturbances. The proposed FNDOB is based on continuous fractional sliding modes, assuring that disturbances and uncertainties are exactly compensated in finite‐time. A representative simulation study for a variable‐speed wind turbine is presented to show the reliability of the proposed scheme, and a comparative analysis with respect to a conventional linear disturbance observer based control is presented.     

Evaluation of MALDI-TOF/MS Technology in Olive Oil Adulteration

Adulteration of extra virgin olive oil (EVOO) by addition of other vegetable oils or lower-grade olive oils is a common problem of the oil market worldwide. Therefore, we developed a fast protocol for detection of EVOO adulteration by mass spectrometry fingerprinting of triacylglycerol (TAG) profiles based on MALDI-TOF/MS. For that purpose, EVOO TAG profiles were compared with those of edible sunflower oil and olive oil composed of refined olive oil and virgin olive oils. Adulteration of EVOO was simulated by addition of sunflower and mixture of refined olive oil and virgin olive oils at 1, 10 and 20% w/w. Results of mass spectrometry TAG profiling were compared with routinely assessed K values for identification of adulteration. MALDI-TOF/MS technology coupled with statistical analysis was proven as useful for detection of adulteration in EVOO at a rate down to 1%. In contrast, standard spectrophotometric methods failed to identify minor adulterations. In addition, the ability of MALDI-TOF/MS in detection of adulteration was tested on EVOO samples from different geographical regions. Results demonstrated that MALDI-TOF/MS technology coupled with statistical analysis is able to distinguish adulterated oils from other EVOO.     

Electrical,mechanical, and piezoresistive properties of carbon nanotube–polyaniline hybrid filled polydimethylsiloxane composites

The electrical, mechanical, and piezoresistive properties of ternary composites based on elastomeric polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and polyaniline (PANI) were studied and compared with those of binary PDMS–CNT composites. The presence of PANI affected the percolating network of the CNTs. At lower PANI concentrations (2.5 and 5%), the conductive network of the CNTs was constructively modified; this led to an enhancement in the conductivity in the sample containing 2% CNTs. A higher PANI content (7.5%) hindered the flow of main charge carriers through the composite. The piezoresistive response of the binary and ternary composites was studied by cyclic experiments under compression loads. In all of the samples, the electrical resistance increased monotonically up to a 10% strain. The reproducibility of the piezoresistive behavior in the binary and ternary composites provided evidence that the fillers could reversibly recover their initial position together with the PDMS chains without a significant displacement with respect to their original positions. The reduction of the piezoresistive sensibility by PANI addition was attributed to the displacement restrictions of the CNTs within the composite under pressure because of the volume exclusion of PANI particles; this maintained the probability of CNT contact and increased the possibility of the formation of new CNT conductive channels. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44780.     

An organic bioactive pro-oxidant behavior in thermal degradation kinetics of polypropylene films

Due to its versatility and low cost, polypropylene (PP) is one of the most widely used polymers in the world. However, since it does not easily degrade in natural environment, various methods have been studied to reduce its lifetime. The pro-degrading additives promote the polymer degradation process by accelerating the polymer degradation under heat and/or UV. Eco-one is an organic bioactive pro-oxidant additive that induces biodegradation when it is incorporated into a polymeric matrix by attracting microorganisms in the biotic phase. The aim of this work was to investigate the abiotic degradability of this organic bioactive pro-oxidant additive in PP films. Thermal oxidation studies of the specimens were carried out to investigate the abiotic degradability. We analyzed compositions of PP films containing 1, 3, and 5% Eco-one by mass. These films were characterized by thermogravimetric analysis to calculate the activation energy (E _α) and to estimate their lifetime. Differential scanning calorimetry was conducted to provide oxidative induction time. The samples were then aged at 80 °C and characterized by Fourier transform infrared spectroscopy to obtain the carbonyl index (CI). Compositions containing 1% Eco-one additive showed the optimal composition with lower activation energy, and shorter predicted lifetime, suggesting easier thermal degradation. Furthermore, high CI was also observed in samples containing 1% additive, indicating thermodegradation for this composition.     

Dietary fatty acids influence the growth and fatty acid composition of the yellow mealworm <Emphasis Type="Italic">Tenebrio molitor</Emphasis> (Coleoptera: Tenebrionidae)

Fat is the second most abundant component of the nutrient composition of the mealworm Tenebrio molitor (Coleoptera: Tenebrionidae) that represents also an interesting source of PUFA, especially n-6 and n-3 fatty acids, involved in prevention of cardiovascular diseases. This study investigated the possibility of modifying the fat content and the FA composition of yellow mealworms through feeding and how this would be influenced by developmental stages, pupal sex, and generation with the future aim of applying this coleopteran as a diet supplement for human health. Growth rate and cumulative mortality percentage on the different feeding substrates were also evaluated to select the optimal conditions for a mass-raising of this insect species. Despite the different fat content in the six different breeding substrates used, T. molitor larvae and pupae contained a constant fat percentage (>34% in larvae and >30% in pupae). A similar total fat content was found comparing larvae and male and female pupae of the second generation to those of the first generation. On the contrary, FA composition differed both in larvae and pupae reared on the different feeding substrates. However, the exemplars reared on the diets based on 100% bread and 100% oat flour showed SFA, PUFA percentages, and an n-6/n-3 ratio more suitable for human consumption; the diet based on beer yeast, wheat flour, and oat flour resulted in a contemporary diet that most satisfied the balance between a fat composition of high quality and favorable growth conditions.     

Permeation of mixtures of organic liquids through polymeric membranes: Role of liquid–liquid interactions

The permeation of pure organic liquids and mixtures of organic liquids through commercial butyl, neoprene, and nitrile membranes was studied using dynamic material deformation (swelling) and permeation techniques. The derived parameters, the breakthrough time (t_BT), steady‐state permeation rate (SSPR), and initial swelling rate (SR), show deviations from additivity for the mixtures, based on the parameters of the pure liquids on a mol fraction basis. In the majority of cases for the three membranes examined, the deviations are independent of the nature of the membranes, and the signs of the deviations for t_BT are opposite to those for SSPR or SR, provided that the membranes are not degraded by one of the solvents. An approach that considers only solvent–solvent interactions based on the enthalpy of mixing was used to predict deviations for mixtures. For mixtures where the enthalpy of mixing is large and exothermic, the permeation of the mixture is less than expected, while for systems where the enthalpy of mixing is large and endothermic, the permeation is larger than expected. A simple semiempirical model predicts the sign and magnitude of the permeation of 73% of the system–permeation property combinations investigated, which show significant deviations from ideality. It is interesting to note that the wrong predictions are for systems where the predictions are positive, that is, for SSPR and SR rates with endothermic systems and for t_BT with exothermic systems. The exceptions also seem to be for systems that correspond to materials having a high resistance to one of the solvents and a very low resistance to the other solvent. Examples of ternary–mixture permeation data are also given and show that, even if two of the pure components do not permeate through a membrane, the membrane will offer little protection if the third component shows a high affinity for the membrane and if the enthalpies of mixing of this component with the other liquids are endothermic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 195–215, 2002     

Microwave Irradiation Effect on Hydrotalcite Synthesis

New synthesis method of hydrotalcites using microwave irradiation is presented, which avoids the autoclave high temperature treatment as well as the long crystallization time. The crystallite size of the obtained solids is smaller than in the conventionally prepared hydrotalcites. The highest irradiation time provided the lowest aluminium incorporation to the hydrotalcite network. Diminishing microwave irradiation time produces purer hydrotalcites. If the gel is irradiated only for two minutes a well crystallized hydrotalcite is obtained.     

Morphology studies of multilayered HDPE/PS systems

Films with alternating layers of high density polyethylene (HDPE) and polystyrene (PS) were prepared by layer‐multiplying coextrusion, using two HDPEs differing in molecular weight. The crystal structure of extremely thin PE layers confined between PS layers was studied by small angle X‐ray scattering (SAXS), wide angle X‐ray diffraction (WAXS), and also by atomic force microscopy (AFM) and differential scanning calorimetry (DSC) technique including MDSC. The morphology of HDPE in the systems studied is greatly affected by the presence of HDPE/PS interfaces. In the HDPE layers, the texture component was observed with lamellae with their basal planes normal to the interface and (200) crystallographic planes parallel to the interface. Thus, the polymer chains in this texture component are parallel to the interface between both polymers. The small fraction of lamellae parallel to the interface in thicker HDPE layers disappears with the thinning of the layers beyond 100 nm. AFM images show in these samples straight, long lamellae positioned edge‐on at HDPE/PS interface. The thickness and perfection of lamellae decrease with the decrease of individual HDPE layer thickness. Those thinner and less perfect lamellae are more susceptible to reorganization during heating as it is observed by MDSC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 597–612, 2006     

Do broadband adoption rates impact a community's health?

As broadband Internet access becomes more common, researchers have focused on the ways that it might improve society. As part of this effort, we seek to determine whether increasing levels of broadband adoption have impacted actual health outcomes by assessing changes in aggregate health measures over time. We use data from 92 metropolitan/micropolitan statistical areas in the USA over the time period 2002–2009 and incorporate a first-differenced approach to uncover the relationship between levels of broadband adoption and various self-reported health outcomes. The results show that higher rates of broadband adoption play a statistically significant role in explaining changes in 9 of the 24 health measures considered. In some cases, higher levels of online activity are related to improved health outcomes. This suggests that policies to increase broadband adoption rates may have significant externalities related to health.     

From types to type requirements: genericity for model-driven engineering

Model-driven engineering (MDE) is a software engineering paradigm that proposes an active use of models during the development process. This paradigm is inherently type-centric, in the sense that models and their manipulation are defined over the types of specific meta-models. This fact hinders the reuse of existing MDE artefacts with other meta-models in new contexts, even if all these meta-models share common characteristics. To increase the reuse opportunities of MDE artefacts, we propose a paradigm shift from type-centric to requirement-centric specifications by bringing genericity into models, meta-models and model management operations. For this purpose, we introduce so-called concepts gathering structural and behavioural requirements for models and meta-models. In this way, model management operations are defined over concepts, enabling the application of the operations to any meta-model satisfying the requirements imposed by the concept. Model templates rely on concepts to define suitable interfaces, hence enabling the definition of reusable model components. Finally, similar to mixin layers, templates can be defined at the meta-model level as well, to define languages in a modular way, as well as layers of functionality to be plugged-in into other meta-models. These ideas have been implemented in MetaDepth, a multi-level meta-modelling tool that integrates action languages from the Epsilon family for model management and code generation.