Stiction detection in control valves using a support vector machine with a generalized statistical variable

Presence of nonlinear factors, such as stiction, hysteresis, and deadband, in a control valve imposes limitations on the performance of the control loop. The importance of assessing the nonlinear conditions of a control valve and detecting its possible defects is a key issue in monitoring performance. Because, this may severely impair the performance of the loop and have a direct impact on the product quality. Valve stiction is one of the most common problems of control valves that cause oscillations in the control loops. Many methods have been proposed to detect this nonlinear phenomenon based on the process model; however, failure to accurately identify the system and the variability of the system parameters make the detection of this factor important independent of the process model. Despite the uncertainty of the measured signals, statistical methods have not applied widely due to their complexities. This paper presents a method for detecting valve stiction occurrence unknown process dynamics by extending a support vector machine (SVM) with a generalized statistical variable.

EGFR mutation detection of lung circulating tumor cells using a multifunctional microfluidic chip

Microfluidics has become a reliable platform for circulating tumor cells (CTCs) detection because of its high integration, small size, low consumption of reagents and rapid response. Here, we developed a multifunctional microfluidic device consists of three parts, including CTCs capture area, single-layer membrane valves area, and microcavity nucleic acid detection and analysis region based on digital polymerase chain reaction (dPCR), allowing CTCs capture, lysis, and genetic characterization to be performed on a single chip. The CTCs capture chip is coupled to the nucleic acid detection chip via a control valve. CTCs were firstly trapped in the CTC capture area, and then lysed using proteinase K to release nucleic acids. Subsequently CTCs lysate was transferred into nucleic acid detection area consisting of 12800 micro-cavity chambers for nucleic acids detection. To evaluate the performance of this chip, this study detected EGFR-L858R mutation in lung cancer cell lines H1975 and A549 cells, as well as leukocytes from normal donors. The results showed that positive signals were only observed in H1975 cells, and the detected value had a high linear relationship with the expected value (R² = 0.9897). In conclusion, this multi-functional microfluidic chip that integrates CTCs capture, lysis and nucleic acid detection can successfully detect gene mutations in CTCs, providing reference for tumor-targeted drugs and precise diagnosis and treatment.

Laboratory experiments and simulation analysis to evaluate the application potential of pressure remote RTC in water distribution networks

Experimental tests were performed to demonstrate applicability of remote real time control (RTC) of pressures for leakage reduction in water distribution networks (WDNs). The experimental tests were carried out in a laboratory pilot system equipped with a motorized plunger valve. A RTC system with the adoption of an integral-type control algorithm was implemented in order to adjust the valve on the basis of pressure measurements acquired in real time. A numerical model of the pilot system was used to verify the suitability of the hypothesis of steady-state conditions in simulating the laboratory tests. The results of the experiments show that, under appropriate calibration of the control algorithm, the RTC system is able to perform effective control of the pressure. Comparison between results of the simulations and experiments reveals that the steady-state model describes correctly the evolution of the pressure control processes observed in the laboratory pilot system, thus opening perspectives for testing remote RTC schemes for leakage management in real WDNs.