Data-based process monitoring has become a key technology in process industries for safety, quality, and operation efficiency enhancement. This paper provides a timely update review on this topic. First, the natures of different industrial processes are revealed with their data characteristics analyzed. Second, detailed terminologies of the data-based process monitoring method are illustrated. Third, based on each of the main data characteristics that exhibits in the process, a corresponding problem is defined and illustrated, with review conducted with detailed discussions on connection and comparison of different monitoring methods. Finally, the relevant research perspectives and several promising issues are highlighted for future work.
A process analysis and quality prediction scheme is proposed based on a stage-based PLS modeling for batch processes. Without any requirement of prior process knowledge, the scheme first divides a batch process into stages of different process characteristics. Subsequently, a strategy is developed to identify stages that have critical influences on concerned qualities, defined as critical-to-quality stages. Within these critical-to-quality stages, an algorithm is then further developed to identify the variables that have significant contributions to the quality variations. Finally, based on the identified nature of quality and stage relationships, a set of algorithms is developed for online quality prediction. The applications of the proposed scheme to injection molding show that the proposed analysis and quality prediction are not only effective but are also able to enhance process understanding and identify specific variables and periods for quality improvement.
Deposition of stable boron-doped diamond (BDD) films on Ti substrates is believed to be very difficult. In the present study, the stability of Ti/BDD electrodes has been significantly improved by using an organic additive, CH2(OCH3)2. The improved electrodes had service lives of 175-264 h under accelerated life test conditions, which are 2.3-3.0 times longer than the service lives of electrodes prepared with the conventional H2 + CH4 mixture. Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) examinations demonstrated thatthe films had well-defined diamond features. The current efficiency (CE) obtained on Ti/BDD was 46.9-78.5% in oxidizing acetic acid, maleic acid, phenol, and dyes, which is 1.6-4.3-fold higher than that obtained on the typical Ti/ Sb2O5-SnO2 electrode. We used a Ti/BDD electrode prepared with H2 + CH4 + CH2(OCH3)2 for over 300 h; its activity remained superior. The successful development of stable and active Ti/BDD electrodes significantly increases the feasibility of industrial applications of anodic oxidation in wastewater treatment.
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