Process Model and Control System for the Glass Fiber Drawing Process

Drawing of glass fibers is an important industrial process used for manufacture of a variety of materials ranging from optical communications cables to fiber filter media. A variety of machines exist for performing the drawing function, but all share similar problems with control of the fiber diameters and breakage of the fibers during the extrusion process. In many cases, control systems are not configured to monitor the most critical process variables-- temperature of molten glass in the furnace, but instead use only furnace crown temperature. Upsets in disturbance variables such as ambient temperature are compensated manually by operators, usually only after significant problems with fiber breakage occur. This work seeks to provide better understanding of the effects of important process variables on the key quality and production parameters such as fiber diameter and production rates, and to develop an effective control model to monitor molten glass temperature and winder speed for good production quality even if some disturbance happens.;First an analytical model of the glass fiber based primarily on Glicksman\u27s work was developed, with the addition of a radiative heat transfer component and the addition of temperature-dependent relationships for physical properties of soda-lime glass. The model is valid for fibers in the central attenuation region, where most of fiber attenuation and breakage happens. Parametric studies have been done using the model to evaluate the effects of variation in the ambient temperature and variation of the molten glass depth in the furnace. These studies have shown that even modest changes ambient temperature and molten glass depth can generate significant changes in the final diameter of the glass fibers.;Based on those results, a state space model of the furnace has been constructed and used as the basis of a state reduced-order estimator to provide an accurate estimate of the temperature of the molten glass at the furnace bottom. A LQR controller with a reference input was applied in the model for bottom glass temperature control. A winder speed controller has been developed in parallel in order to compensate for the long time delay between application of burner firing rate changes and the response of the thermal system. Then multivariable control analysis was done on variation of ambient temperature and variation of molten glass depth. The control model manipulates both the winder speed and the burner firing rate, bringing the process back to design conditions even if some disturbance occurs, and allows greater flexibility and more accurate quality control for the glass fiber drawing process

Modeling and correction analysis of regional ionospheric modeling

The Global Navigation Satellite System (GNSS), due to its all-weather lobal monitoring and high precision, makes it possible to use GNSS observation data to accurately extract the total electron content (TEC) of the ionosphere and to study ionospheric activities. At the same time, the delay error caused by the ionosphere to GNSS signals is also one of the main sources of error in GNSS positioning. For regional users, using as few stations as possible to establish an ionospheric TEC model within the region has higher efficiency and range practicability. This paper realizes the establishment of a regional ionospheric TEC model based on spherical harmonics, and establishes an ionospheric TEC model in the 15∼45°N and 105°∼135°E regions, which is compatible with IGS (International GNSS Service, IGS) and CAS (Chinese Academy of Sciences, CAS), the overall difference is more than 70% within ±3TECU

Application of an Improved Seeds Local Averaging Algorithm in X-ray Spectrum

As an element content analysis technology, X-ray fluorescence spectrometry can be used for quantitative or semiquantitative analysis of the element content in the sample, which is of great significance for mineral census and spent fuel reprocessing. Due to the limitation of the inherent energy resolution of the detector itself, the accuracy of X-ray fluorescence analysis is difficult to be greatly improved. In some applications, even if the semiconductor detector with the best energy resolution is used, the characteristic peaks of different elements cannot be completely separated. Therefore, greatly improving the energy resolution of the detection system is a hot issue in the existing research field. To solve these problems, this paper analyzes the advantages and disadvantages of the traditional MCA (multichannel analyzer) and SLA (seeds local averaging) algorithm and proposes an ISLA (improved seeds local averaging) algorithm based on mathematical statistics. In the section of theoretical derivation, the principle of ISLA algorithm is described, whose theoretical characteristics and spectral results with different parameters are derived and simulated. In the application effect evaluation, the spectrum obtained by each method is analyzed in detail. Simulation and experimental results show that the spectrum obtained by SLA algorithm has a smaller full width at half maximum than that obtained by MCA, but the seed average process in SLA algorithm also reduces its counting rate. The optimized ISLA algorithm can not only effectively reduce the full width at half maximum of the spectral line and sharpen the spectrum peak but also compensate for the loss of the count rate of SLA algorithm