Full-scale Error Research Articles

Design of a Low-Cost Thermal Dispersion Mass Air Flow (MAF) Sensor

There is a need for a low-cost sensor to be used in many practical applications, such as the control of the air–fuel ratio in combustion burners, which measures the mass flow rate of fluid. This paper focuses on the design, calibration, and testing of a mass flow sensor operating on the principle of thermal dispersion. The developed sensor implements a digital proportional-integral controller which regulates the body temperature of a heated element, recognized as a thermistor, located in the stream of the fluid flow to a constant difference with respect to the ambient air temperature. The power dissipated by this heated element was referenced to known mass flow rates of air to determine the relationship between the dissipated power and ambient temperature to the measured mass flow rate. The inclusion of air flow conditioners, which filtered unwanted debris and delivered a more laminar air flow, was imperative to the success of the design. The designed sensor was proven to measure the incoming mass air flow through a duct, in the presence of moderate disturbances in the intake air pipe and for a wide range of ambient air temperatures, with a maximum full-scale error of 5.5% and a range up to 80 kg/h.

Design of the Apparatus for Detecting and Transmitting Pressure Signals on the Probe of Electrical Impedance Scanning of Breast

In order to explore the relationship between the impact of detection probe and human contact pressure on its imaging result in the electrical impedance scanning techniques of breast, there is a need to design a set of device to extract pressure signal on EIS detection probe and transmit to the host in a long distance. The design uses Wheatstone full-bridge converter based on the resistance-type strain gauge as an extraction method for the pressure signal. After pre-amplification processing of the extracted signals, the voltage signal is converted into 4-20mA of current signal for long-line transmission via XTR106 chip. By the use of digital potentiometer chip replacing the adjustable resistance in the circuit, and by virtue of MCU chip and ADC chip, the system is characterized by automatic zero set of the full-bridge converter of sensor and adaptive control of amplifier circuit gain, thus realizing high-precision measurement and transmission of pressure signal at four locations of detection probes. The simulation and actual measurement results show that, after the automatic “zero set” operation, the output error of the system is less than ± 0.5%; the amplifier gain is within an adjustable range of 75-500, so that the full-scale output error of the system is less than ± 1%. The test results verify the reliability and validity of the system.

Localization of CO2 Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO2 leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%.

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells.

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5–60 m3/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2–60 m3/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow.

Low-coherence wavelength shifting interferometry for high-speed quantitative phase imaging.

We propose low-coherence wavelength shifting interferometry and demonstrate its application to quantitative phase imaging of dynamic specimens. By shifting the source wavelength, multiple interferograms of the sample can be acquired at different spectral bands. A sample phase is thus encoded in the phase step between consecutive acquisitions. For the particular case of four-band imaging, we show that the phase can be extracted with a modified Carré algorithm. We describe signal demodulation in detail and discuss its implication on system implementation. A swept laser-based Mach-Zehnder interferometer is used to demonstrate the technique for real-time imaging of live sperm cells at 62.5 Hz. The dynamic dry mass of the sperm head is measured with a full-scale error of ±2%, validating the technique's capability for high-sensitivity, high-speed quantitative phase imaging.

On-line measure of donkey's milk properties by near infrared spectrometry

The ranchers handle donkeys breeding in small livestock farms and there is a need to supply a suitable tool to assess milk characteristics.To this aim, near infrared (NIR) spectroscopy was assessed through nine statistical methods: partial least squares, principal components, multivariate adaptive splines, regression trees using M5′ method, least squares support vector machine, artificial neural network, regression trees, ensemble regression trees and regularized least squares regression. These methods were implemented using a forward sequential feature selection algorithm; their predicting capability was validated with ten-fold cross validation; different types of spectra pre-processing methods were tested.The trials confirmed that NIR analysis is an efficient method for quantitative analysis of protein, lactose and dry matter content of donkey's milk with a full-scale prediction error (FSPERR) of 3.0%, 4.4% and 4.5% respectively. Furthermore, a 16 NIR light emitting diodes (LED) device was investigated using simulation; in this case the prediction models of protein content showed the best FSPERR (3.1%), followed by those of dry matter content (7.0%) whereas those of the lactose content showed the worst (19.8%). These results could be used to design a low cost NIR LED device for the real-time control of donkey's milk in breeding farms.

Two-Color Pyrometer for Process Temperature Measurement During Machining

A fast fiber-optic two-color pyrometer operating on the optical communication bands is designed for temperature measurements in machining processes. Off-the-shelf low-loss fiber-optic demultiplexers and optoelectronics equipment are used in order to obtain a cost-effective sensing solution while reducing both the temperature measurement error and the minimum measurable temperature. The system is capable of measuring highly localized temperatures without using collimation lens. The designed pyrometer allows measuring temperature in the range from 300 to 650 °C, achieving a full-scale temperature error as low as 4%. Factors influencing the temperature measurements are studied in order to identify the sensor limitations, such as a possible damage on the end of the optical fiber, the spectral loss attenuation and responsivity, or the distance between the fiber end and the target. Finally, this pyrometer is applied in a turning process, using a fiber-optic sensor embedded on a standard tool holder. Temperature measurements on the Inconel 718 are reported showing a good agreement with the simulations.

Enhanced Linearisation Approach for CTA Linearisation based on Evolutionary Algorithm

An unsophisticated process is presented to obtain constant temperature anemometer (CTA) linearised outcomes. In order to improve the CTA linearity the objective function of the nonlinear ratio metric logarithmic is used in the determination of minimising the optimal values of mean square error which enhance the performances of the CTA signal linearity. The evolutionary strategy assumes to have reliably process of generating the optimal values and linearised the function by using multi objective covariance matrix adapted evolution strategy (MO-CMAES). The obtain value is hired with the parameters of various linearization to normalize the optimal values. The proposed approach is implemented and simulated the outcomes by using Lab VIEW 7.1. Experimental analysis is carried out with the evaluation of root mean square error and full-scale error. It is preserved for associating the proposed performances with the methods of a transducer's reported of linearization. Experimental outcomes sustain that the optimised process of proposed evolutionary approach of nonlinear function is linearized with better improvement in CTA linearisation and it performed the system measurement and control process.

Improvable method for Halon 1301 concentration measurement based on infrared absorption

Halon 1301 has attached much interest because of its pervasive use as an effective fire suppressant agent in aircraft related fires, and the study of fire suppressant agent concentration measurement is especially of interest. In this work, a Halon 1301 concentration measurement method based on the Beer–Lambert law is developed. IR light is transmitted through mixed gas, and the light intensity with and without the agent present is measured. The intensity ratio is a function of the volume percentage of Halon 1301, and the voltage output of the detector is proportional to light intensity. As such, the relationship between the volume percentage and voltage ratio can be established. The concentration measurement system shows a relative error of the system less than ±2.50%, and a full scale error within 1.20%. This work also discusses the effect of temperature and relative humidity (RH) on the calibration. The experimental results of voltage ratio versus Halon 1301 volume percentage relationship show that the voltage ratio drops significantly as temperature rises from 25 to 100°C, and it decreases as RH rises from 0% to 100%.

Development and validation of a computational model of the knee joint for the evaluation of surgical treatments for osteoarthritis

A three-dimensional (3D) knee joint computational model was developed and validated to predict knee joint contact forces and pressures for different degrees of malalignment. A 3D computational knee model was created from high-resolution radiological images to emulate passive sagittal rotation (full-extension to 65°-flexion) and weight acceptance. A cadaveric knee mounted on a six-degree-of-freedom robot was subjected to matching boundary and loading conditions. A ligament-tuning process minimised kinematic differences between the robotically loaded cadaver specimen and the finite element (FE) model. The model was validated by measured intra-articular force and pressure measurements. Percent full scale error between FE-predicted and in vitro-measured values in the medial and lateral compartments were 6.67% and 5.94%, respectively, for normalised peak pressure values, and 7.56% and 4.48%, respectively, for normalised force values. The knee model can accurately predict normalised intra-articular pressure and forces for different loading conditions and could be further developed for subject-specific surgical planning.

Analysis of stress distributions under lightweight wheeled vehicles

In recent years, the need for reliable modeling tools for lightweight robotic systems deployed on various terrains has spurred research efforts into development of vehicle terrain interaction (VTI) models. This paper presents an analysis of rigid wheels – dry sand interaction and compares experimental results with predictions from established terramechanics theory. A novel experimental setup, based on sensing elements placed on the wheel surface, allows inference of normal and tangential stress at the wheel-terrain interface. A particle image velocimetry (PIV) analysis is used to study the soil kinematics under the wheel. The analysis of stress profiles shows that stress patterns under lightweight vehicle wheels conform reasonably well to established terramechanics theory developed for heavy vehicles. For the wheel under investigation, the stress distribution had minor variation along wheel width for low slip conditions. The wheel model proposed by Wong and Reece was analyzed in light of the stress and soil kinematics measurements available. It was found that, by appropriately characterizing the model coefficients c1 and c2, and understanding the physical meaning of the shear modulus kx, it is possible to obtain torque, drawbar force, and sinkage predictions within 11% (full scale error) of experimental data.

Study of Digital Dissolved Oxygen Analytical Sensor of ppb-Level

This paper introduces the structure and working principles of the digital dissolved oxygen (DO) analytical sensor of ppb-level. The new-style tri-electrode electrochemical sensor composed of working electrode (WE), auxiliary electrode (AE), and reference electrode (RE) is reported in this paper because of the limit reaction area of the WE, the long reaction time, and the little reaction cavity of the existing sensors. We prepare a nano-porous gold electrode with high specific surface area to increase the area ratio of the AE and the WE. It makes the new-style tri-electrode electrochemical sensor steadier, more reliable and stronger in anti-interference. This paper also introduces the design of the work system, which is composed of hardware circuit, signal sampling and processing circuit, and temperature compensation circuit. Compared with the DO analyzer made in the Swiss Orbisphere Company (tri-electrode structure), the precision of self-made DO analyzer reach to ppb-level and the full scale error is less than ±3%. In conclusion, the new-style tri-electrode electrochemical sensor can be widely used to measure DO in boiler feed water in thermal power plants.

Research the wet gas flow measurement based on dual-throttle device

In this paper a novel flow measurement device composed of a long throat Venturi tube and a V-cone was proposed to deal with the wet gas flow measurement without separation, and a new metering method was put forward based on the triple differential pressures. The correlations were based on the gas densiometric Froude number, gas–liquid density ratio, and the differential pressure ratios, which were then compared and validated by the laboratory and field tests. The laboratory test results showed that the uncertainty of relative errors for the gas and liquid flow rates were less than 3% and 6%, respectively. The field test results showed that the uncertainty of relative errors for the gas flow rates before correction varied from 5.53% to 11.57%. After correction the uncertainty of relative errors for gas flow rate varied from 1.37% to 3.22% and full-scale error for liquid flow rate was less than ±10%.

Information Extraction Method of SO<sub>2</sub> Using Differential Optical Absorption Spectroscopy

The measuring principle of SO2, which is the main gaseous contaminants in flue gas, is given based on the differential optical absorption spectroscopy (DOAS). And the structure and composition of the measurement system are introduced. In the aspect of obtaining the absorption feature of measured gas, an information extraction method using statistics is presented for measuring the concentration of SO2. The nonlinear calibration and the temperature compensation for the system were executed. In the lab, the full scale error of the retrieving concentration is less than 0.5%FS. And the measuring result is-9.47mg/m3during the concentration of SO2is zero.

Design of 45nm Switched Inverter Scheme (SIS) ADCs for Low Power and High Speed Applications

The Analog to Digital converters (ADC) play a very important role in today’s world of electronic systems. The requirement of present applications demands high speed, low power dissipation, minimum area, low noise and application specific resolution. Out of the various types of ADCs available the flash ADC is most popular for its highest conversion rate and its wide applications. On the down side the flash ADC dissipates high power due to the presence of resistance ladder. The power dissipation further increases with increase in resolution. In this research two different approaches are presented which eliminates the resistor ladder completely and hence reduce the power demand drastically. The first approach is Switched Inverter Scheme (SIS) ADC; it is realized for 3 bits using 7 comparator circuits of varying size in CMOS 45nm technology with Predictive Technology Model (PTM). The test result obtained indicates an offset error of 0.014 LSB. The full scale error is of -0.112LSB. The gain error is of 0.07 LSB, actual full scale range of 0.49V, worst case DNL & INL each of -0.3V. The power dissipation for the SIS ADC is 207.987 µwatts; Power delay product (PDP) is 415.9 fWs, and the area overhead is 1.89µm 2 . The second approach is Sleep transistor SIS ADC. This approach shows 71% improvement in power dissipation. Whereas PDP is found to be 107.3 fWs and area overhead is 1.94 µm2 for Sleep transistor SIS ADC.

Characterization, modeling and vibration control of a flexible joint for a robotic system

This paper presents the experimental characterization and vibration control of a flexible robotic system. For this work, a test bench was built to characterize the harmonic drive (HD) and joint components, while control algorithms were designed and compared to minimize vibration. Encoder accuracy was critical since the difference in the measurements between two encoders was used to evaluate the vibrational behavior of the test set-up. Therefore, a laser tracker was used to characterize the error of the output encoder. Real-time compensation using this technique achieved an angular position accuracy of 50 µrad. Four rosette strain gauges were fixed to the HD’s flexible spline to determine its torsion. To reduce torque ripple, a real-time correcting function was applied. It was thus possible to reduce the error to 0.3% of the full-scale error. Two vibration control strategies were developed, namely, singular perturbation and feed-forward control. Simulation results showed that both control strategies greatly reduced vibration response compared to a common rigid control. However, test results showed that good vibration control could only be achieved with the feed-forward approach: the singular perturbation technique generated too much torque ripple to the motor. A feed-forward controller can quickly stabilize the link, achieving the same settling time as with the rigid control algorithm.

Parametric excitation of a micro Coriolis mass flow sensor

We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.

Analysis of Analog to Digital Converter for Biomedical Applications

This paper presents an ADC which can be used for biomedical application like pacemaker. For the low-power operation, monotonic switching scheme and operating voltage reduction have been implemented in the design. The 10bit 1.8V rail-to-rail (SAR) ADC is realized using UMC 0.18µm CMOS process. Simulations are performed by spectre simulation. From static performance, offset error and full scale error are noticed. This performance issue can be corrected by reducing discharge in capacitor by implementing sampling switch as bootstrapped switch and proper selection of common-mode voltage where 20fF is used as unit capacitance.

Temperature compensation of micromachined silicon hot wire sensor using ANN technique

Temperature is one of the most important factors influencing accurate silicon sensor devices and is one of the largest sources of error in measurement. In this paper, a model based on Neural Networks (NN), has been implemented to generate fluid velocity data, knowing fluid temperature measurements. The proposed model based on neural networks can provide the calibrated response characteristics irrespective of change in the sensor characteristics due to change in ambient temperature. The NN-based sensor model automatically calibrates and compensates with high accuracy for the nonlinear response characteristics and nonlinear dependency of the sensor characteristics on the environmental parameters. Through extensive simulated experiments, we have shown that the NN-based silicon hot wire sensor model can provide flow speed readout with a maximum full-scale error of only 1.5% over a temperature range from 0 to 40°C for nonlinear dependencies.

Feasibility of novel four degrees of freedom capacitive force sensor for skin interface force

BackgroundThe objective of our study was to develop a novel capacitive force sensor that enables simultaneous measurements of yaw torque around the pressure axis and normal force and shear forces at a single point for the purpose of elucidating pressure ulcer pathogenesis and establishing criteria for selection of cushions and mattresses.MethodsTwo newly developed sensors (approximately 10 mm×10 mm×5 mm (10) and 20 mm×20 mm×5 mm (20)) were constructed from silicone gel and four upper and lower electrodes. The upper and lower electrodes had sixteen combinations that had the function as capacitors of parallel plate type. The full scale (FS) ranges of force/torque were defined as 0–1.5 N, –0.5-0.5 N and −1.5-1.5 N mm (10) and 0–8.7 N, –2.9-2.9 N and −16.8-16.8 N mm (20) in normal force, shear forces and yaw torque, respectively. The capacitances of sixteen capacitors were measured by an LCR meter (AC1V, 100 kHz) when displacements corresponding to four degrees of freedom (DOF) forces within FS ranges were applied to the sensor. The measurement was repeated three times in each displacement condition (10 only). Force/torque were calculated by corrected capacitance and were evaluated by comparison to theoretical values and standard normal force measured by an universal tester.ResultsIn measurements of capacitance, the coefficient of variation was 3.23% (10). The Maximum FS errors of estimated force/torque were less than or equal to 10.1 (10) and 16.4% (20), respectively. The standard normal forces were approximately 1.5 (10) and 9.4 N (20) when pressure displacements were 3 (10) and 2 mm (20), respectively. The estimated normal forces were approximately 1.5 (10) and 8.6 N (10) in the same condition.ConclusionsIn this study, we developed a new four DOF force sensor for measurement of force/torque that occur between the skin and a mattress. In measurement of capacitance, the repeatability was good and it was confirmed that the sensor had characteristics that enabled the correction by linear approximation for adjustment of gain and offset. In estimation of forces/torque, we considered accuracy to be within an acceptable range.