A pattern based strategy for using multidimensional sensors in process control

Multidimensional sensors can deliver vast and rich information about the industrial processes operation. At industrial level, they are becoming widely available for supervising tasks. However, their use at control level is not very widespread, since there are no standard methodologies for including the information provided by this type of sensors into existing control systems. This paper describes the traditional approach to include multidimensional information into conventional control systems, and proposes a new structure based on pattern recognition. The latter makes use of artificial neural networks and finite state machines as a framework for designing the control system. The main characteristics and limitations of both approaches are illustrated by the image based control of an experimental fluidization bed.     

Morphology and mechanical properties of heterophasic PP–EP/EVA/organoclay nanocomposites

The effect of vinyl acetat (VA) on the morphological, thermal stability, and mechanical properties of heterophasic polypropylene–(ethylene‐propylene) copolymer (PP–EP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites was studied. Tailored organoclay C20A was selected to enhance the exfoliation of the clay platelets. Depending on the VA content, there were two morphological organoclay populations in the systems. Both populations were directly observed by scanning transmission electron microscopy and measured by wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The content of VA in EVA originated spherical and elongated morphologies in the resultant nanocomposites. High‐VA content led to a better intercalation of the organoclay platelets. Measurement of thermal properties suggested that higher VA decreases thermal stability in samples both with and without organoclay, although nanocomposites had higher thermal stability than samples without clay. The storage modulus increased both with nanoclay and VA content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Understanding particles emitted from spray and wall-guided gasoline direct injection and flex fuel vehicles operating on ethanol and iso-butanol gasoline blends

Traffic-related pollutants are an ever-growing concern. However, the composition of particle emissions from new vehicle technologies using relevant current and prospective fuel blends is not known. This study tested four current and up-and-coming vehicle technologies with nine fuel blends with various concentrations of ethanol and iso-butanol. Vehicles were driven on both the federal test procedure (FTP) and the unified cycle (UC). Additional tests were conducted under steady-state speed conditions. The vehicle technologies include spray-guided gasoline direct injection (SG-GDI), wall-guided gasoline direct injection (WG-GDI), port-fuel injection flex fuel vehicle (PFI-FFV), and a wall-guided GDI-FFV. The fuels consisted of 10–83% ethanol and 16–55% iso-butanol in gasoline. The composition of soot, water-insoluble mass (WIM), water-soluble organic mass, and water-insoluble organic mass (WIOM), and OM was measured. The majority of emissions over FTP and UC were water-insoluble (>70%), and WIOM contributes mostly to OM. PFIs have lower soot and particulate matter (PM) emissions in comparison to the WG-GDI technology even while increasing the renewable fuel content. SG-GDI technology, which has not penetrated the market, show promise as soot and PM emissions are comparable to PFI vehicles while preserving the GDI fuel economy benefits. The WIM fraction in GDI-FFV consistently increased with increasing ethanol concentration. Lastly, the impact of the future vehicle emissions and traffic pollutants is discussed. SG-GDI technology is found to be a promising sustainable technology to enhance fuel economy and also reduce PM, soot, and WIM emissions.

Copyright © 2017 American Association for Aerosol Research     

Ti/TiSiNO Multilayers Fabricated by Co-sputtering

Multilayer coatings of titanium/ titanium silicon oxynitride (Ti/TiSiNO) were fabricated on stainless steel 434-L substrates by sputtering technique using Ti and TiSiO targets. The multilayers were formed by alternately and simultaneously introducing and suspending a 4-sccm flow of nitrogen together with an interchange of targets, during different time periods of 1.0, 2.0, 3.0 and 4.0 min; thus, we obtained intervals of different thickness by alternating the target (Ti) and using only argon, and later with both targets (Ti + TiSiO) and the two gases (Ar + N₂). The final thickness was within a range of 0.4-0.8 μm, depending on the number of multi layers obtained by means of glow discharge optical emission spectroscopy. The structure, topography, color, durability and nanofriction were analyzed in accordance with the growth parameters used. It was found that the values of hardness depend on the number of layers deposited. The greatest number of layers, 48 of them, was obtained with a time period of 1 min, thereby attaining the maximum value of hardness and the minimum value for both the friction coefficient and the RMS, with 31 GPa, 7.42 × 10^?3 and 0.17 nm, respectively. The phases found correspond to Ti₂N, Si₃N₄, rutile phase of TiO₂ and Ti. The TiO₂ phase was corroborated with Raman dispersion spectroscopy. The color of the coatings was affected by variation in the working pressure, which varied because of the internal process of reactive sputtering.     

Current-source converter on-line pattern generator switchingfrequency minimization

On-line pulsewidth modulation (PWM) pattern generators for current-source rectifiers and inverters offer a number of control advantages over off-line optimized patterns. However, when implemented using the principles which apply to voltage-source inverter PWM pattern generators, the switching frequency is equal to: (1) the carrier frequency in standard carrier-based implementations and (2) a function of the cycle frequency, sequence of space vectors, and selection of the zero space vector in space vector implementations. This paper shows that this frequency can be reduced to one-half of the respective frequencies. Two pattern generators are investigated: (1) an analog on-line carrier-based technique, namely, the modified dead-band technique and (2) a digital on-line space vector-based technique, where advantage is taken of the extra zero state available in current-source converters. It is shown that the switching frequency reduction is achieved with no penalty in the line current harmonic distortion. Moreover, a significant reduction of AC line current distortion is obtained with the modified dead-band technique for modulation indexes greater than 0.4. The principles of operation of the proposed schemes are explained, Experimental results on a 5 kVA current-source rectifier and a 5 kVA current-source inverter confirm the feasibility and features of the proposed pattern generators     

Sex differences in neuropsychological functioning of first-episode and chronically ill schizophrenic patients

OBJECTIVE: The purpose of this study was to determine whether men and women with schizophrenia demonstrate differences in cognitive abilities. METHOD: Two cohorts of patients with schizophrenia, an acute first-episode and a chronically hospitalized group, were evaluated with a neuropsychological battery and compared with a normal group of subjects. RESULTS: After adjustment for age, age at onset, and premorbid IQ, male chronic patients performed worse than female chronic patients on measures of visual memory. These differences were eliminated after control for symptom severity. No other differences were found in cognitive function between men and women in either cohort. CONCLUSIONS: Sex differences in cognitive function in schizophrenic patients are not robust findings.     

Powder metallurgical processing of Co-28%Cr-6%Mo for dental implants: Physical, mechanical and electrochemical properties

The parameters for conventional powder-metallurgical production of a CoCrMo alloy for dental implants were determined. With the application of these parameters an alloy with sufficient green density, low porosity after sintering, considerable hardness and spontaneously passive behavior in the Ringer solution can be achieved. The comparison of samples with different sintering temperatures revealed that a slight variation of the sintering temperature can have a considerable effect on the physical, mechanical and electrochemical properties of the alloy.     

Formation of bromoform in irradiated titanium dioxide suspensions with varying photocatalyst, dissolved organic carbon and bromide concentrations

We report the formation of bromoform in TiO₂ suspensions (P25) under simulated solar UV irradiation at different concentrations of photocatalyst (0.5-1.5 g L⁻¹) as well as initial concentrations of bromide ions (1-3 mg L⁻¹) and 2,4-dihydroxybenzoic acid (2-10 mg L⁻¹). The extent of bromoform formation (3-17 μg L⁻¹) was most strongly affected by the amount of photocatalyst present and by the initial bromide concentration, increasing either of which leads to increased bromoform formation. Important interaction effects were observed when simultaneously increasing the concentrations of TiO₂ and bromide as well as of bromide and DHBA. The time it takes for bromoform to appear in measurable concentrations in the irradiated TiO₂ suspensions was between 10 and 90 min and most strongly depended on the initial concentration of dissolved organic carbon present in the suspensions, along with the amount of photocatalyst, also in interaction with the initial bromide concentration.     

Selective harmonic elimination and current/voltage control incurrent/voltage-source topologies: a unified approach

This paper presents a unified approach for generating pulsewidth-modulated patterns for three-phase current-source rectifiers and inverters (CSR/Is) that provides unconstrained selective harmonic elimination and fundamental current control. The approach uses the chopping angles or gating patterns developed for voltage-source rectifiers and inverters in combination with a logic circuit to generate the gating patterns for CSR/Is. The circuit also includes naturally and symmetrically distributed shorting pulses. Thus, the approach avoids the hassle of positioning the shorting pulses and defining and solving a set of nonlinear equations dedicated to CSR/Is. Moreover, the approach can eliminate an even or odd arbitrary number of harmonics (e.g., fundamental current control and elimination of the 5th, 7th, and 11th harmonics). This is an improvement over existing techniques and a new approach to pattern generation. Simulated and experimental results for both static and dynamic operating conditions are presented in order to validate the effectiveness of the approach     

Compensated carrier PWM synchronization: a novel method to achieveself-regulation and AC unbalance compensation in AC fed converters

The compensated carrier PWM synchronization (CCPS) method for AC-fed PWM power converters is presented. The method provides a solution to PWM converters fed by industrial power systems (IPSs). Such environments usually present unbalances and magnitude fluctuations of AC voltages. Those circumstances impair standard PWM techniques because low-order harmonics are produced and DC-link regulation is poor. To reduce these undesirable effects produced by IPS, a method based on using independently compensated carriers per phase was conceived. In particular, CCPS prevents second harmonic generation and achieves converter self-regulation. The method can be used with any PWM technique and bidirectional power flow. The evaluation of CCPS is based on a complete performance comparison of a PWM rectifier with and without CCPS for various known PWM techniques