A robust strategy for real-time process monitoring

An operator support system (OSS) is proposed to reliably retain salient information in a high dimensional and correlated database, to uncover linear and nonlinear correlations among variables, to reconstruct failed/unavailable sensors, and to assess process-operating performance in the presence of noise and outliers. The proposed strategy carries out the task in three steps. In the first step, a robust tandem filter is used to suppress noise and reject any outlying observations. Next, an orthogonal nonlinear principal component analysis network is utilized to optimally retain a parsimonious representation of the system. In the final step, the process status is checked against the normal operating region defined by kernel density estimation, and failed/unavailable sensors are reconstructed via constrained optimization and the trained network. The strategy is demonstrated in real-time using a pilot-scale distillation column.     

On the global stability of conventional PID control for a class of chemical reactors

The stabilization properties of derivative control for chemical reactor stabilization have been rarely studied in the literature. In a pioneering work, Aris and coworkers (textitChem. Eng. Sci. 1959; 11 :199–206.) used linear analysis to show that derivative control offers greater stabilization flexibility than proportional control. The aim of this work is to show that mixed derivative and proportional control can yield global stabilization for a large class of continuously stirred tank reactors (CSTR) characterized by having stable isothermical dynamics. The stability proof exploits the structure of CSTR models where the nonlinearity is concentrated in the chemical reaction kinetics. It is shown that the proportional mode is a type of energy shaping to induce a unique equilibrium point, while the derivative mode can be interpreted as a global damping injection to reduce undesired transient effects, such as temperature overshooting and oscillations. A numerical example is used to illustrate the different features of mixed proportional and derivative control in chemical reactor dynamics. Copyright © 2011 John Wiley & Sons, Ltd.     

Rough Surfaces Profiles and Speckle Patterns Analysis by Hurst Exponent Method

In this work, a conventional surface roughness comparator is used to perform an analysis of different textures. The Hurst exponent method for the characterization of optical profiles and speckle digital patterns obtained from the comparator was used. By implementation of a simple experimental setup with minimum alignment, information about specific points on the comparator for different roughness was obtained. The processing and analysis of optical signals and images obtained by reflection allowed calculation of Hurst coefficients, revealing a relation between surface roughness, optical profiles and speckle patterns. The setup simplicity and Hurst analysis suggest their combined application on surface metrology.     

Optimal Selection of Wavelet Coefficients for Electrocardiograph Compression

This paper presents a simple method to implement a complete on‐line portable wireless holter including an electrocardiogram (ECG) monitoring, processing, and communication protocol. The proposed algorithm significantly reduces the hardware resources of threshold estimation for ECG compression, using the standard deviation updated with each new input signal sample. The new method achieves superior performance in terms of hardware complexity, channel occupation and memory requirements, while keeping the ECG quality at a clinically acceptable level.     

Hydrodynamics of a superheated steam vacuum fluidized bed

Hydrodynamics of a superheated steam vacuum fluidized bed was experimentally studied. In these experiments, eight different types of large particles (1970–7430 μm) were used. In all cases, a behavior similar to that found in an air fluidized bed was observed. The minimum fluidization velocity was found to be increasing with decreasing operating pressure. In the case of employing superheated steam, the minimum fluidization conditions are established at a lower velocity than using air as the fluidizing medium. These tendencies are attributed to the variation of the mean free path of molecules. On the other hand, the experiments showed that the bed voidage in the minimum fluidization conditions is almost insensitive to the variation of the operating pressure. Several equations were developed to predict the minimum fluidization velocity. The values provided by these equations were compared with the experimental data as well as with the predictions of the correlations presented in the technical literature.     

Increased effectiveness of the Trichoderma harzianum isolate T‐78 against Fusarium wilt on melon plants under nursery conditions

BACKGROUND: The use of isolates of the genus Trichoderma to control Fusarium wilt in melon plants is one of the most recent and effective alternatives to chemical treatments. In this work we have studied the immobilization of the isolate Trichoderma harzianum T‐78 on different carriers as an efficient method to control vascular Fusarium wilt of melon in nurseries. Different formulations were developed: liquids (spore suspension, guar gum and carboxymethylcellulose) and solids (bentonite, vermiculite and wheat bran). RESULTS: The introduction of F. oxysporum resulted in a significant decrease in seedling fresh weight. The treatments which gave a lesser reduction in weight and showing a greater biocontrol effect were the liquid conidial suspension and the solid treatments with bentonite and superficial vermiculite. Microbiological analyses revealed that the conidial suspension and all the solid treatments, except wheat bran, significantly decreased F. oxysporum populations. Of all the treatments assayed, bentonite produced the greatest decline in the F. oxysporum population. CONCLUSIONS: The most effective treatments against Fusarium wilt on melon plants were the solid treatments bentonite and superficial vermiculite. These two treatments gave the greatest plant weight, the lowest percentage of infected plants and the greatest T. harzianum population throughout the assay. Copyright © 2009 Society of Chemical Industry     

Resveratrol metabolites have an antiproliferative effect on intestinal epithelial cancer cells

Trans-resveratrol (RV) is an active polyphenol with numerous physiological properties including antitumour activity, especially in colon cancer. RV is metabolized in the intestine and then in the liver to sulphated and glucuronidated forms that are exported to target organs. After exerting their effects, they are eliminated in the urine and stools. There are few and contradictory findings on the biological effects of RV metabolites. On the basis of RV metabolism, we selected three metabolites RV 3-O-sulphate, RV 3-O-glucuronide and RV 4′-O-glucuronide, and studied their effects on cell growth inhibition, the cell cycle and apoptosis using human adenocarcinoma cell line (Caco-2 cell) cultures.     

The contribution of syntactic–semantic approach to the search for complementary literatures for scientific or technical discovery

The present paper tries to show that the current state of the art in syntactics and semantics, in computer systems based on the theory of inventive problem solving known as TRIZ, may help in the task of literature based discovery. With a structured and logic cause linkage between concepts, LBD could be faster and with less expert involvement at the beginning of the LBD process. The author tries to demonstrate the concept with two different problems: the hearing and balance problem known as Meniere’s disease, and to some of the current problems in the lithium air batteries for electric vehicles. By using open literature based discovery from An to Bn and from Bn to Cn, and with the logic relationships of real causes and effects approach, the author finds several relative new concepts such as vitamin A. Other concepts as niacin or fish oil, are also found, as potential to help in the Meniere’s disease. Secondly, using such procedure the author is able to find patents from disparate domain of expertise, as patents about odor control or metal casting.     

Evaluation of the fracture behavior of multilayered polypropylene sheets obtained by coextrusion

The mechanical and fracture behavior of multilayered sheets (up to three layers) is presented. The sheets were processed by plane coextrusion‐calendering using two polypropylene‐based materials, isotactic polypropylene homopolymer (H0), and an ethylene–propylene block copolymer (C1) with 5.5% ethylene content in weight. Combining these materials five different sheets were produced, (H0, C1, H0–C1, H0–C1–H0, and C1–H0–C1), with an overall thickness of 0.5 mm. The processing variables (temperature, extrusion rate, calendering speed, etc.) were set constant among the different structures to facilitate the evaluation of the results. The structure of the sheets was characterized with wide angle X‐ray scattering (WAXS). The mechanical behavior was determined from dumbbell tensile specimens in the melt flow (MD) and transverse to the melt flow (TD) directions. The fracture parameters were determined by the essential work of fracture (EWF) technique in mode I in both MD and TD directions. The results show variations on the induced orientation of the sheets, with remarkable differences on the fracture properties. The poor fracture resistance of the homopolymer (H0) film in TD is improved through coextrusion with C1, obtaining the best results for toughness in the case of the three‐layered sheets. POLYM. ENG. SCI., 47:1365–1372, 2007. © 2007 Society of Plastics Engineers