Wavelet-based multiscale statistical process monitoring: A literature review

Data that represent complex and multivariate processes are well known to be multiscale due to the variety of changes that could occur in a process with different localizations in time and frequency. Examples of changes may include mean shift, spikes, drifts and variance shifts all of which could occur in a process at different times and at different frequencies. Acoustic emission signals arising from machining, images representing MRI scans and musical audio signals are some examples that contain these changes and are not suited for single scale analysis. The recent literature contains several wavelet-decomposition-based multiscale process monitoring approaches including many real life process monitoring applications. These approaches are shown to be effective in handling different data types and, in concept, are likely to perform better than existing single scale approaches. There also exists a vast literature on the theory of wavelet decomposition and other statistical elements of multiscale monitoring methods, such as principal components analysis, denoising and charting. To our knowledge, no comprehensive review of the work relevant to multiscale monitoring of both univariate and multivariate processes has been presented to the literature. In this paper, over 150 both published and unpublished papers are cited for this important subject, and some extensions of the current research are also discussed.     

Dengue NS1 Detection used Chemically Modified Porous Silicon Microcavity (PSMC)

Porous silicon is an adaptable platform for developing label-free biosensors with high sensitivity and low cost. Dengue viral infection is detected based on commercially available ELISA (Enzyme-linked immunosorbent assay) based serological assays and not on the more difficult and costly procedures of Haemagglutination inhibition (HI), virus isolation or RT-PCR (Real Time polymerase chain reaction). In this paper, a novel diagnostic method for the detection of Dengue virus has been developed because it is still blooming and is becoming a major health concern around the world. Fabrication of a silicon wafer to create a Porous Silicon Microcavity (PSMC) has been used to increase the surface area for the immune reaction and hence the probability of the Dengue virus detection after chemical modification with adhesives and bio-functionalization is high by the treatment of antibody and antigen. Finally, a specific antigen-antibody reaction was obtained.     

Removal of SO2 by activated carbon fibers in the presence of O2 and H2O

This work describes the potential capability of activated carbon fibers (ACFs) in continuously removing SO₂ from inert atmosphere without requiring further regeneration. A tubular reactor packed with ACF was used to study the conversion of SO₂ into H₂SO₄ in the presence of O₂ and H₂O with varying concentrations of SO₂ (3000-10,000 ppm), O₂ (10-20%), and H₂O (10-70%) and temperatures (313-348 K). The experiments were carried out on two precursors (viscose rayon and phenolic resin) based ACFs. The breakthrough data revealed that the steady-state SO₂ concentration levels at the reactor exit increased with increasing inlet SO₂ concentration and decreased with increasing concentration levels of O₂ as well as H₂O. Increase in the reaction temperature was found to moderately enhance the steady-state exit concentration levels of SO₂. The viscose rayon-based ACF exhibited higher SO₂ removal activity in comparison to the phenolic resin-based ACF. A mathematical model was developed to predict the gas concentration profiles in the reactor, incorporating the mass transfer in the bed as well as within the ACF pores, along with the surface reactions on the ACF. The model predictions agreed reasonably well with the data.     

Removal of SO2 by Activated Carbon Fibre Impregnated with Transition Metals

Phenolic resin based activated carbon fibres (ACF) impregnated with oxides of various transition metals were investigated for the catalytic oxidation of SO₂ into H₂SO₄. Oxidation was carried out in the packed bed tubular reactor in the presence of O₂ and H₂O. The activity of the various metals impregnated on ACF was observed to be in the order, Cu>Ni>Co>Cr. It was found that the metal oxides were dispersed as monolayer on ACF up to ～5% (w/w) loading, beyond which crystallites formation occurred. A kinetic mechanism for the catalytic oxidation of SO₂ into H₂SO₄ was proposed and incorporated in a transport model developed to explain the experimental breakthrough data.     

Metallurgical Investigation on Embrittlement of Copper Cable of an Electric Motor

Journal of Failure Analysis and Prevention - Copper wires used in the cable of an electric motor were found to be embrittled after a burn up. A metallurgical investigation (microstructural...     

Catalytic Potential of a New Polymer-Anchored Multisite Phase Transfer Catalyst in the Dichlorocarbene Addition to Indene

The popularity of triphase catalysis in industries is due to straightforward catalyst recovery from reaction mixture. In this work we report a facile preparation a new polymer-anchored multisite phase transfer catalyst viz., polymer-anchored-2-benzyl-2-phenyl-1,3-bis(triethylmethylene ammonium chloride) (PABPBTAC) using polystyrene-based cross-linked beads. In order to ascertain the catalytic efficiency of the new heterogeneous catalyst, we studied its catalytic activity in the conversion of indene into dichlorocyclopropyl indene using chloroform and sodium hydroxide. Comparative catalytic efficiency of the new polymer-anchored multisite phase transfer catalyst with polymer-supported single site onium salts revealed that the new heterogeneous phase transfer catalyst is highly active than others. Further, from the influence of variation of experimental parameters, such as [substrate], [catalyst], [NaOH], stirring speed and temperature on indene conversion was studied in detail.     

Embrittlement of a Duplex Stainless Steel in Acidic Environment Under Applied Cathodic Potentials

Hydrogen-induced degradation of mechanical properties of a duplex stainless steel in 0.1N H₂SO₄ solution has been studied under in situ cathodic charging conditions. Significant reductions in percentage of elongation, toughness, and time to failure were noticed due to the ingress of hydrogen into the material at various applied cathodic potentials in the range of −200 to −800 mV (SCE). Cleavage fractures were identified mainly in the ferritic phases. Crack growth was observed to be inhibited by the austenite phase. However, depending on the severity of the environment, both the ferrite and austenite phases could be embrittled. At less negative potentials, presence of surface film and low hydrogen fugacity seemed to control hydrogen ingress in the metal. Addition of thiosulfate to the acidic solution further degraded the mechanical properties of the steel at the applied cathodic potential.     

Quality Enhancement of UF-clarified Pear Juice using Adsorbent and Weak-base Resins at Different Temperatures

ABSTRACT: The efficiency of polymeric adsorbent (PA) and weak‐base anion (WBA) resins at different temperatures to improve the quality of UF‐clarified pear juice was investigated. UF‐clarified and partially concentrated pear juice was passed through PA and then through WBA resins at 23, 30, and 50 °C. Treated juice samples were analyzed for pH, titratable acidity, color, phenolics, minerals, sugars, and organic acids. Treated juice showed 85% reduction in both color and titratable acidity. There was also a significant reduction (P < 0.05) in the content of polyphenolics and organic acids. No significant changes (P > 0.05) in the nutritional value were detected. Temperatures higher than 23 °C did not significantly (P > 0.05) improve the efficiency of the resins tested.     

ULTRASOUND-ASSISTED N-ALKYLATION OF PHTHALIMIDE UNDER PHASE-TRANSFER CATALYSIS CONDITIONS AND ITS KINETICS

In this work, N-butylation of potassium phthalimide was carried out under ultrasonic-assisted phase-transfer catalysis condition using n-bromobutane as an alkylating agent. The mechanism of the solid-liquid reaction of alkyl halide and potassium salt of phthalimide in an organic solvent was verified in this work. The kinetics of the reaction depends on the amount of catalyst, agitation speed, type of quaternary ammonium salts, volume of water, type of organic solvent, volume of organic solvents, temperature, and the frequency of the ultrasound. Five different onium salts were examined for the reaction and tetrahexylammonium bromide showed maximum catalytical activity. An improvement of the reaction outcome (yield and reaction time) was achieved through the immersion of the reactor into an ultrasound bath. The rate of the reaction is two times faster under ultrasonic condition (k_app = 10.7 × 10^?3 min^?1) than silent condition (k_app = 5.5 × 10^?3 min^?1) and is five times faster when the reaction is carried out in acetonitrile medium than in cyclohexane medium. The reaction is very fast under anhydrous condition. Based on the experimental data, a rational mechanism for the reaction is proposed.