Flow Heating System Research Articles

Improved detection of incipient anomalies via multivariate memory monitoring charts: Application to an air flow heating system

Detecting anomalies is important for reliable operation of several engineering systems. Multivariate statistical monitoring charts are an efficient tool for checking the quality of a process by identifying abnormalities. Principal component analysis (PCA) was shown effective in monitoring processes with highly correlated data. Traditional PCA-based methods, nevertheless, often are relatively inefficient at detecting incipient anomalies. Here, we propose a statistical approach that exploits the advantages of PCA and those of multivariate memory monitoring schemes, like the multivariate cumulative sum (MCUSUM) and multivariate exponentially weighted moving average (MEWMA) monitoring schemes to better detect incipient anomalies. Memory monitoring charts are sensitive to incipient anomalies in process mean, which significantly improve the performance of PCA method and enlarge its profitability, and to utilize these improvements in various applications. The performance of PCA-based MEWMA and MCUSUM control techniques are demonstrated and compared with traditional PCA-based monitoring methods. Using practical data gathered from a heating air-flow system, we demonstrate the greater sensitivity and efficiency of the developed method over the traditional PCA-based methods. Results indicate that the proposed techniques have potential for detecting incipient anomalies in multivariate data.

Amalgamation of anomaly-detection indices for enhanced process monitoring

Accurate and effective anomaly detection and diagnosis of modern industrial systems are crucial for ensuring reliability and safety and for maintaining desired product quality. Anomaly detection based on principal component analysis (PCA) has been studied intensively and largely applied to multivariate processes with highly cross-correlated process variables; however conventional PCA-based methods often fail to detect small or moderate anomalies. In this paper, the proposed approach integrates two popular process-monitoring detection tools, the conventional PCA-based monitoring indices Hotelling's T2 and Q and the exponentially weighted moving average (EWMA). We develop two EWMA tools based on the Q and T2 statistics, T2-EWMA and Q-EWMA, to detect anomalies in the process mean. The performances of the proposed methods were compared with that of conventional PCA-based anomaly-detection methods by applying each method to two examples: a synthetic data set and experimental data collected from a flow heating system. The results clearly show the benefits and effectiveness of the proposed methods over conventional PCA-based methods.

A nonparametric approach to design robust controllers for uncertain systems: Application to an air flow heating system

This paper presents an approach to design robust fixed structure controllers for uncertain systems using a finite set of measurements in the frequency domain. In traditional control system design, usually, based on measurements, a model of the plant, which is only an approximation of the physical system, is first built, and then control approaches are used to design a controller based on the identified model. Errors associated with the identification process as well as the inevitable uncertainties associated with plant parameter variations, external disturbances, measurement noise, etc. are expected to all contribute to the degradation of the performance of such a scheme. In this paper, we propose a nonparametric method that uses frequency-domain data to directly design a robust controller, for a class of uncertainties, without the need for model identification. The proposed technique, which is based on interval analysis, allows us to take into account the plant uncertainties during the controller synthesis itself. The technique relies on computing the controller parameters for which the set of all possible frequency responses of the closed-loop system are included in the envelope of a desired frequency response. Such an inclusion problem can be solved using interval techniques. The main advantages of the proposed approach are: (1) the control design does not require any mathematical model, (2) the controller is robust with respect to plant uncertainties, and (3) the controller structure can be chosen a priori, which allows us to select low-order controllers. To illustrate the proposed method and demonstrate its efficacy, an application to an air flow heating system is presented.

Kugelstrahlen bei erhöhter Temperatur mit einer Druckluftstrahlanlage

de

A variable temperature controller for use with a transfer gas flow heating system and powdered samples

The authors describe the design of an economic, closed-loop, variable temperature controller which incorporates a number of circuit design innovations. It was developed to control and measure the temperature of powdered samples and designed to minimize the time interval between measurements made at successive temperatures using a gas flow system for heating. Direct measurement of the sample temperature improved the temperature setting repeatability and enabled the onset of exothermic chemical reactions in the sample holder to be monitored. A detailed description is given of the version developed to upgrade an open-loop, commercial, high-temperature, electron paramagnetic resonance 9 GHz cavity, heater and power supply system. This controller achieves a short and long-term stability +or-0.1 degrees C and the temperature of a powdered sample can be determined with an accuracy of +or-1 degrees C and a precision and repeatability of +or-0.1 degrees C in the interval from near ambient to 600 degrees C.

A distributed energy management and security system

A multi-microprocessor-based energy management and security system is presented. A number of 1-bit microprocessors (MC 14500) controlling the energy consumption and security system in different locations are connected in a star configuration to an 8-bit general purpose microprocessor (MC 6800). The system proved to be flexible, reliable and cost effective. The system hardware and software is analysed and described. An example of a system interface for an air flow heating system is presented.