New Method For On-line Measurement Research Articles

Double Optical Fiber Temperature Compensation Method for Measurement of Interface Pressure Between Simulated Cable and Accessory at High Temperatures

Reliable interface pressure between cables and accessories is closely associated with the safe operation of a power cable system. Using an external optical fiber Bragg grating temperature-compensating curvature sensor, a new method for online measurement of the interface pressure between a cable and an accessory at high temperatures is proposed. On the basis of the sensing principle of a fiber Bragg grating, a mathematical pure bending model, and a model of a thick-walled cylinder, a fiber Bragg grating temperature-compensating curvature sensor is fabricated using Dow Corning Sylgard-184 silicone rubber. The interface pressures of 10 kV cable accessories with different expansion rates at different temperatures are measured. The results of the measurements show that the temperature-compensated deviation of wavelength measurements made by the fiber grating curvature sensor ranges from -2.59% to 5.50%. The interface pressure between the cable and the accessory gradually increases with an increase in temperature from 30 to 60 °C. The results are consistent with the results of measurements made using a traditional piezoelectric sensor. This method is expected to evaluate the long-term reliability of the interface pressure of cable accessories in actual complex-temperature environments.

Mass flow rate measurement of gas-liquid two-phase flow using acoustic-optical-Venturi mutisensors

The measurement of multiphase flow parameters is essential for the online monitoring of industrial production and energy metering. In this paper, a multi-sensor experimental measurement device is designed based on NIR, acoustic emission sensors, and throated Venturi. The measurement information is decomposed using modal decomposition, and the characteristic variables of the gas volume fraction are extracted by flow noise decoupling and light attenuation analysis. A new gas volume fraction model is proposed based on Gradient Boosting Decision Tree (GBDT) through feature-level fusion, and the Mean Absolute Percentage Error (MAPE) of the gas volume fraction prediction models is within 4% for the three flow patterns. A new flow rate model is established based on the Homogeneous and Collins models. Laboratory results indicate that the MAPE of the flow rate model is 1.56%, and 98.61% relative deviations are within ±20% error band. The study provides a new method for online measurement of multiphase fluid motion and a theoretical basis for sensing mechanism and measurement of multiphase flow.

A new method for online measurement of the concentration of working fluids in absorption refrigeration systems

This paper proposes a new method for online measurement of the concentration of working fluids in absorption refrigeration systems: electrical conductivity is measured to determine the concentration of the solution. Compared with the common density-concentration method, electrical conductivity-concentration method has the same accuracy but helps to save cost when applied in absorption systems with ammonia–salt solutions. This novel method is also suitable for systems with traditional working fluids like water–lithium bromide solution. Electrical conductivities of ammonia–lithium nitrate, ammonia–sodium thiocyanate and water–lithium bromide solutions were measured between (293.15 and 333.15) K, using an Industrial Conductivity Meter. The ammonia mass fraction varied from 0.35 to 0.48 for ammonia–lithium nitrate solution and from 0.35 to 0.50 for ammonia–sodium thiocyanate solution. For water–lithium bromide solution, the mass fraction of lithium bromide was within the range of 40%–60%. The experimental data were correlated as a function of temperature and composition using the extended Casteel–Amis equation. In addition, correlations of refrigerant mass concentration as a function of electrical conductivity and temperature of the solution are proposed.

A New Method for on-Line Measurement of Viscosity

Based on the increase type rotary encoder and the cantilever elastic element, a new kind of single cylinder rotary online viscosity sensor is designed, This article mainly introduces the principle of this sensor operation and the design calculation of the elastic element. And then further this paper shows how the finite-element method of the ANSYS is used to analyze the maximum deflection and the stress of the elastic element. Finally, the measurement error of is analyzed.

Design of Forming Shape Measurement System for Laser Molten Pool in Laser Fabricating

In order to study forming shape distribution of laser molten pool in laser fabricating, a CCD-based image detection system was developed. The system mainly consists of a CCD-based detector, optical elements, an image acquisition card and its special software. Experiments on shape measurement of the laser molten pool were carried out. It was shown that 2D morphology and the dimension of laser molten pool could be measured in real time. The (X, Y) dimension of the laser molten pool in laser cladding was (2.6 mm, 2.5 mm) with an approximately ellipsoidal shape. Laser cladding parameters were optimized according to the measurement results. It was a non-destructive measurement method, which would be a new method for online measurement and feedback control in laser fabricating.

A new method for on-line measurement of moisture content during fluid-bed granulation

A new method for on-line measurement of moisture content during fluid-bed granulation

An innovative online VFA monitoring system for the anerobic process, based on headspace gas chromatography

A new method for online measurement of volatile fatty acids (VFA) in anerobic digesters has been developed based on headspace gas chromatography (HSGC). The method applies ex situ VFA stripping with variable headspace volume and gas analysis by gas chromatography-flame ionization detection (GC-FID). In each extraction, digester sample was acidified with H(3)PO(4) and NaHSO(4), then heated to strip the VFA into the gas phase. The gas was sampled in a low friction glass syringe before injected into the GC for measurement. The system has been tested for online monitoring of a lab-scale CSTR reactor treating manure for more than 6 months and has shown good agreement with off-line analysis. The system is capable of measuring individual VFA components. This is of advantage since specific VFA components such as propionic and butyric acid can give extra information about the process status. Another important advantage of this sensor is that there is no filtration, which makes possible application in high solids environments. The system can thus be easily applied in a full-scale biogas reactor by connecting the system to the liquid circulation loop to obtain fresh sample from the reactor. Local calibration is needed but automatic calibration is also possible using standard addition method. Sampling duration is 25-40 min, depending on the washing duration, and sensor response is 10 min. This is appropriate for full-scale reactors, since dynamics within most biogas reactors are of the order of several hours.

A new method for on-line measurement of the volumetric oxygen uptake rate in membrane aerated animal cell cultures

Oxygen is a key substrate in animal cell metabolism and its consumption is thus a parameter of great interest for bioprocess monitoring and control. A system for measuring it based on an oxygen balance on the liquid phase was developed. The use of a gas-permeable membrane offered the possibility to provide the required quantity of oxygen into the culture, while avoiding problems of foaming or shear stress generally linked to sparging. This aeration system allowed moreover to keep a known and constant k L a value through cultures up to 400 h. Oxygen uptake rate (OUR) was measured on-line with a very good accuracy of ±5%, and the specific OUR for a CHO cell line was determined during batch (growth phase) and continuous culture as, respectively, equal to 2.85×10 −13 and 2.54×10 −13 mol O 2 cell −1 h −1. It was also shown that OUR continuous monitoring gives actually more information about the metabolic state of the culture than the cell concentration itself, especially during transition phases like the end of the growth phase in a batch culture.

Etiology of ventriculomegaly in choroid plexus papilloma.

In order to test the hypothesis that overproduction of cerebrospinal fluid can cause the hydrocephalus seen in choroid plexus papillomas, adult mongrel dogs with and without hydrocephalus were subjected to high pressure intraventricular infusions of artificial cerebrospinal fluid (CSF). Pre- and postinfusion volumes were calculated, using a new method for on-line measurement of ventricular volume involving linear measurements from Conray ventriculograms. Ventricular volumes increased an average of 8% in 36 h. The dogs previously made hydrocephalic by the intracisternal injection of kaolin had a significant volume increase (34% in 36 h). Overproduction of CSF alone can produce hydrocephalus, but the presence of hydrocephalus in choroid plexus papillomas is more likely to be a result of the complex interaction of CSF overproduction and partial restriction of CSF flow.