This article reexamines the problem of estimating symmetrical sequence components, more specifically, the optimal estimation of the magnitude and phases of sequence components. We first address and ...compare different setups for the optimal Kalman filter, including those that make use of three-phase measurements and those where the measurements are transformed by the Clarke transform, in the well-known direct and quadrature (dq) reference frame. Our main contribution is to show that by disregarding some Clarke transformed measurements in the estimation of zero, positive, and negative sequence components, which is the common practice, almost always lead to an estimator with suboptimal performance. Moreover, we show that optimal performance can be recovered if all Clarke transformed measurements are made available to the filter. We use simple numerical examples to explain our results, and we finish this article with a unified set of guidelines or best practices regarding the estimation of sequence components by optimal Kalman filters.
Cardiovascular diseases (CVD) are the most important cause of mortality globally. Nevertheless, the World Health Organization have declared that a precise and quick recognition of susceptible ...individuals to develop CVD is imperative to combat those illnesses. Additionally, developing countries need affordable alternatives to effectively prognosticate cardiovascular events. Therefore, the objective of this study was to assess well-established clinical prognostic markers in Mexican women to identify affordable, specific, and useful tools to predict cardiovascular events.
A cross-sectional study was performed including 340 healthy women. Anthropometric and clinical measurements were acquired from all enrolled individuals. Also, a blood sample of each participant women was obtained to complete biochemical analyses (triglycerides, glucose, total cholesterol, LDL cholesterol, and HDL cholesterol), and serum asymmetric dimethylarginine (ADMA), and adipocyte-fatty acid binding protein (FABP4) determinations. Finally, with anthropometric, clinical and biochemical determinations, atherogenic indices (Framingham risk score, Castelli's risk index, and atherogenic index of plasma) were estimated.
A mean value of 6.5 ± 7.2 was detected for the Framingham risk score, 3.7 ± 1.3 for Castelli's risk index, and 0.12 ± 0.22 for the atherogenic index of plasma (AIP). Circulating mean ADMA and FABP4 levels found in assessed women were 0.68 ± 0.34 mmol/L and 20.3 ± 16.6 ng/mL, respectively. Furthermore, strong positive relationships (p <0.05) between AIP and serum FABP4 and ADMA concentrations were detected after adjustment by traditional CVD risk factors.
In conclusion, AIP could be recommended as a potential biomarker in the early diagnosis of CVD events in developing countries.
This paper presents a methodology aimed at extracting features to obtain information that will highlight disturbances related to the field of power quality. Due to the concept of smart grids, it is ...clear that the classification of the disturbances should be undertaken using smart meters, so that a large amount of data corresponding to the voltage and current waveforms are not exchanged using the communication channels, i.e., between smart meter and Utility's database server. Thus, it is necessary to ensure a balance between computational effort (arising from the implementation of algorithms on hardware) and the satisfactory performance of the algorithm for the classification of disturbances. Based on the assumption that the classification task is onerous, this paper proposes a step of feature extraction that may be calculated and analyzed offline using synthetic waveforms/signals, which are subsequently validated using field measurements. It should be noted that this offline analysis is required to determine the most relevant features for the process of classifying each disturbance. However, in order to establish the effectiveness of the feature extraction step, the response of decision trees of the C4.5 type and of artificial neural networks of the multilayer perceptron type were verified during the phase of disturbance classification. In short, good results were obtained that corroborate the hypothesis that the feature extraction step is necessary to classify disturbances effectively and with low computational effort.
Crystallographic texture and grain–boundary distribution are introduced as a new method of reducing susceptibility to crack formation and propagation. In this work, slow strain rate tests (SSRT) were ...performed on fully martensitic ultra-high strength Fe–18Ni–Co steel in 0.6M NaCl atmosphere at −1.2 VSCE to investigate hydrogen embrittlement (HE). Micro and meso-texture in both crack stricken and crack free regions were characterized using electron backscattering diffraction (EBSD) technique, to find a pattern between crystallographic orientation and HE susceptibility. The Taylor factor analysis was used to determine the grains with higher susceptibility to crack initiation and propagation. The results showed that cracks can initiate and propagate through //ND oriented grains, while {111} and {110}//ND fibers indicate higher resistance path for crack propagation. Moreover, the high amount of deformed fraction with high stored energy acts as one of the main reasons for high susceptibility of this steel against SSRT. It is concluded that the susceptibility of high strength Fe–18Ni–Co steel to HE can be reduced through crystallographic texture control and grain boundary engineering.
In this work, slow strain rate tests (SSRT) were performed on fully martensitic ultra-high strength Fe–18Ni–Co steel. The results showed that the LAGBs and CSLs linked to {001}//ND cannot stop the crack initiation and propagation. While in free cracked regions, LAGBs and CSLs linked to {111} and {110} are more effective in preventing crack nucleation. Also, crack favorably propagated along high Taylor factor grains exhibited less resistance against crack propagation. Display omitted
•Slow strain rate tests were performed in Fe-8Ni‐Co steel in 0.6M NaCl at −1.2VSCE to investigate hydrogen embrittlement.•The LAGBs and CSLs linked to {001}//ND cannot stop the crack initiation and propagation.•In contrast, the LAGBs and CSLs linked to {111} and {110}//ND are more resistant against crack formation.•Crack tended to propagate through nearest grains with high Taylor factor.
This paper presents a compact embedded fuzzy system for three-phase induction-motor scalar speed control. The control strategy consists in keeping constant the voltage-frequency ratio of the ...induction-motor supply source. A fuzzy-control system is built on a digital signal processor, which uses speed error and speed-error variation to change both the fundamental voltage amplitude and frequency of a sinusoidal pulsewidth modulation inverter. An alternative optimized method for embedded fuzzy-system design is also proposed. The controller performance, in relation to reference and load-torque variations, is evaluated by experimental results. A comparative analysis with conventional proportional-integral controller is also achieved.
Herein, we report a class of novel lanthanide-doped self-supported layered double hydroxide (LDH) nanotubes featuring a combination of micro- and mesoporosity. The synthesis of the nanotubes has been ...achieved by a soft-templating strategy. Incorporation of La
3+
, Pr
3+
, Nd
3+
, Sm
3+
, Eu
3+
, Gd
3+
or Tb
3+
in the LDHs assisted the self-assembly of the double hydroxide layers onto the surface of Pluronic P-123 worm-like micelles, enabling the formation of the nanotubes. Removal of the micellar template provides accessibility to the mesopores, yielding a network of hollow cylindrical nanotubes with internal diameter of about 10 nm. An antenna molecule (benzene-1,3,5-tricarboxylate, BTC) is hosted in their 1-nanometre-wide micropores. Upon UV excitation, the nanotubes emit light in a set of wavelengths ranging from the ultraviolet to the infrared.
The incorporation of triply charged lanthanides in layered double hydroxides (LDHs) enables the curvature of the LDH sheets, unlocking the possibility of using a soft templating strategy to produce a class of luminescent, hierarchical LDH nanotubes.
Summary
Demand‐side management comprises a portfolio of actions on the consumers' side to ensure reliable power indices from the electrical system. The home energy management system (HEMS) is used to ...manage the consumption and production of energy in smart homes. However, the technology of HEMS architecture can be used for the detection and classification of power quality disturbances. This paper presents low‐voltage metering hardware that uses an ARM Cortex M4 and real‐time operating system to detect and classify power quality disturbances. In the context of HEMS, the proposed metering infrastructure can be used as a smart meter, which provides the service of power quality monitoring. For this type of application, there is a need to ensure that the development of this device has an acceptable cost, which is one of the reasons for the choice of an ARM microprocessor. However, managing a wide range of operations (data acquisition, data preprocessing, disturbance detection and classification, energy consumption, and data exchange) is a complex task and, consequently, requires the optimization of the embedded software. To overcome this difficulty, the use of a real‐time operating system provided by Texas Instruments (called TI‐RTOS) is proposed with the objective of managing operations at the hardware level. Thus, a methodology with low computational cost has been defined and embedded. The proposed approach uses a preprocessing stage to extract some features that are used as inputs to detect and classify disturbances. In this way, it was possible to evaluate and demonstrate the performance of the embedded algorithm when applied to synthetic and real power quality signals. Consequently, it is noted that the results are significant in the analysis of power quality in a smart grid scenario, as the smart meter offers low cost and high accuracy in both detecting (an accuracy rate above 90%) and classifying (an average accuracy rate above 94%) disturbances.
This paper proposes a methodology for monitoring power quality using a real‐time operation system embedded in low‐cost hardware. An architecture for demand‐side management focusing in power quality is described. The developed smart meter is a low‐cost one in order to encourage consumer participation in demand‐side management programs. Fast Fourier transform and statistics metrics are used for features extraction in order to decrease the computational cost. The proposal can be extended with demand response algorithms, Internet of Things, and loads control.
•A biphasic setup was used to study naphthenic acid corrosion (NAC) in stagnant conditions.•EIS was used for NAC study at ambient temperature.•Global and localized electrochemical techniques were ...used to characterize the corroded steel.•NAC occurs in the aqueous phase, near the oil/water interface.•Corrosion is enhanced by the increasing concentration of naphthenic acids.
Naphthenic acid corrosion of steel is studied in crude oil/aqueous phase system at ambient temperature, using a biphasic stagnant liquid without emulsification, by means of electrochemical measurements and surface analysis. The in-situ electrochemical impedance is assigned to the processes occurring at the aqueous phase. Corrosion occurred only in the region of the aqueous phase, as crater-shaped pits that eventually coalesced, generating a nearly uniform attack in the vicinity of the oil phase. The impedance values, normalized to the aqueous region only, reveal corrosion rate increasing with the ratio of crude oil/water. Despite the localized character of the anodic oxidation, the iron naphthenate corrosion products became partitioned between the two phases. Surface-resolved electrochemical techniques in aqueous solution revealed enhanced activity of the regions pre-exposed to oil.
A major public health concern in Mexico is the natural contamination of groundwater with fluoride and arsenic. Therefore, this work aimed to evaluate the magnitude of human health risk after ...determining fluoride and arsenic concentrations in groundwater samples (
n
= 50) from the Metropolitan area of the city of San Luis Potosi, Mexico. Fluoride levels in water were determined via a potentiometric method using an ion-selective electrode. Arsenic concentrations in water samples were determined with an Atomic Absorption technique. Subsequently, a probabilistic health risk assessment was developed (Monte Carlo Analysis). Fluoride levels in water ranged from 0.20 to 3.50 mg/L. For arsenic, the mean level found in the assessed water samples was 15.5 ± 5.50 μg/L (range: 2.50–30.0 μg/L). In addition, when the probabilistic health risk assessment was completed, a mean HI (cumulative hazardous index) of higher than 1 was detected, indicating a high NCR (non-carcinogenic risk) for children and adults. According to the results found in this study, exposure protection campaigns are imperative in the Metropolitan area of the city of San Luis Potosí, Mexico, to successfully diminish exposure to arsenic and fluoride and, as a consequence, decrease the NCR in the population living in that region of Mexico.
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