Temperature Drift Research Articles

A Startup Control Method for Plasma Lamps by Using Fractional-N Phase-Locked Loop Microwave Driver

The microwave-driven plasma light source has the feature of the full spectrum, similar to sunlight, and has broad application prospects. Startups of plasma lamps are very difficult since the plasma density and the resonator impedance are changing constantly with the warm-up process and the RF driver can hardly couple the power to the plasma efficiently. This paper presents a startup control method for plasma lamps by using an integrated fractional-N phase-locked loop (PLL) as the RF signal source. An RF control module including a 21 dBm RF source with a band of 430–460 MHz and detection circuits for the RF driver is developed, and the startup process of the plasma lamp is further studied by analyzing the return loss of the resonator under the plasma load. According to the test result, the maximum frequency deviation of the RF control module is 3.3 kHz over the working temperature range of −40–80 °C. The designed RF control module is used to drive a high-power amplifier to start the plasma lamp automatically. It takes 79 s to achieve the stable arc operation from the gas breakdown. The return loss of the resonator is −26 dB, with an incident power of 171 W and reflected power of 418 mW, indicating that the RF driver and the plasma achieve good coupling. Compared with continuous wave, the luminous flux of the lamp powered by RF pulse improves by 18% under the same electric power. This startup control method has stable performance, small temperature drift, and an effective control function for plasma lamps.

New temperature stable YbTaO4 microwave dielectric ceramic with monoclinic structure

A new temperature-stable YbTaO4 ceramic with monoclinic structure was fabricated using the traditional solid-state method. The relationship between the structure and properties was studied using Rietveld refinement and complex chemical bond theory. The change in the dielectric constant of YbTaO4 ceramics is affected by the relative density. The values of the dielectric constant obtained by complex chemical bond theory and the Clausius–Mossotti equation are consistent with the experimental results. Research based on complex chemical bond theory indicates that Ta–O bonds have the highest bond energy and bond iconicity, which have a decisive influence on dielectric polarizabilities and dielectric performance. The microwave dielectric properties of the YbTaO4 ceramic sintered at 1675 °C were obtained as follows: dielectric constant εr = 18.52, quality factor Q×f = 21928 GHz, and temperature drift τf = 1.28 ppm/°C.

Enhancing thermal and optical properties for liquid quantum-dot-based self-loop system toward laser illumination by controlling the layer location

White light sources based on laser diodes are considered to be the next-generation light sources owing to their high luminous efficiency, high luminous flux, and excellent directivity. Quantum dots (QDs) are new fluorescent materials that have been widely used in lighting and displays. However, when used for high-power illumination, QDs excitation and emission are accompanied by obvious attenuation problems owing to their reabsorption effect and low stability in high temperature environment. To solve these problems, this study proposes three types of QD-based self-loop systems for laser illumination and analyzes their thermal and optical properties. White light is obtained by exciting red and green QDs using a blue laser. The three types of self-loop converters are green-QD-front type (structure I), red-QD-front type (structure II), and hybrid type (structure III). The average temperatures of the excitation region of structures I and II were maintained at approximately 37.3 °C and 37.0 °C, respectively, which were both lower than that of the hybrid structure (46.7 °C). The radiation flux of structure I only attenuated by 15.6% after laser irradiation for 120 min. Furthermore, the shift in color coordinates was the smallest. When the laser driving current was changed from 500 mA to 1500 mA, the correlated color temperature (CCT) drift was only 474 K. We believe that these results will provide guidelines for QD-based laser-driven illumination.

THERMOSTABLE REFERENCE CURRENT AND VOLTAGE SOURCES FOR HIGH-LINEAR ANALOGUE-CODE-ANALOGUE SYSTEM

DC sources and reference voltage sources are widely used in various electronic devices: analog-to-digital and digital-to-analog converters, DC amplifiers, sample-and-hold devices, stabilized voltage sources, and others. At the same time, the accuracy and temperature characteristics of the latter largely depend on the same characteristics of direct current and voltage sources, which are subject to stringent requirements. There are quite a lot of different approaches to the construction of reference voltage and current source circuits with thermal compensation. The most famous of them – with the use of thermally compensated zener diodes operating in reverse breakdown mode. However, devices based on them have a high power consumption and low efficiency and a high level of noise, and it is difficult to implement temperature drift compensation due to a wide spread of temperature characteristics. The so-called bandgap circuits are also widely used – transistor reference voltage sources, the value of the reference voltage of which is determined by the band gap of the semiconductor. The most famous of them are Vidlar’s bandgaps and Brokau’s bandgaps. The specificity of all bandgap circuits is the rigid binding of the output voltage to the band gap of the semiconductor. The article proposes an alternative approach to the construction of direct current and voltage sources, which consists in the use of circuits of two-pole direct current sources. A new approach to the construction of thermally stable reference current sources based on bipolar transistors using the band gap voltage of a semiconductor and current mirrors is proposed. The principles of operation of the circuits are described and the possibility of achieving thermal compensation is proved. Computer modelling of the static characteristics of the proposed reference current sources, in particular, the temperature drift of the currents, has been carried out. A new approach to the construction of thermally stable reference voltage sources based on bipolar transistors with the use of thermally stable reference current generators is proposed. Analytical expressions are obtained that describe operation of circuits of reference voltage sources according to the proposed approach. A method for increasing the loading capacity of these reference voltage sources is proposed.

Multichannel ±2 order orbital angular momentum mode converter based on an elliptical-core helical intermediate-period fiber grating.

We propose and demonstrate a multichannel ±2 order orbital angular momentum (OAM) mode converter based on an elliptical-core helical intermediate-period fiber grating (E-HIPFG). By decreasing the grating pitch to ∼17.5 µm, ten wavelength channels are observed in the transmission spectrum of the E-HIPFG. Within the wavelength range of 1240-1650 nm, the ±2 order OAM modes are identified at each wavelength channel. The proposed E-HIPFG is ∼2.6 mm in length, which is more than one order of magnitude shorter than the conventional device, and thus may be more resistant to external disturbances, such as bending. Furthermore, the device exhibits an ultralow temperature drift of ∼5.84 pm/°C. Therefore, the proposed E-HIPFG can be a good candidate for a multichannel higher-order OAM mode converter.

The Dynamics of 0-Group Herring Clupea harengus and Sprat Sprattus sprattus Populations Along the Norwegian Skagerrak Coast

Coastal areas are important habitats for early life stages of many fish species. These habitats are used as nursery grounds and can provide a significant contribution to the recruitment of a fish population. In 1919, standardized sampling with a beach seine along the Norwegian Skagerrak coastline was established mainly to target 0-group fish. Here, we focus on Atlantic herring and European sprat to explore whether inter-annual variability in the abundance of these species is indicative of variability in recruitment. We investigated if the abundance of 0-group herring and sprat are affected by environmental factors. Further, the beach seine abundance indices were compared with recruitment estimates of neighboring stocks. There was a clear correlation between herring and sprat abundance in the beach seine samples. While sprat abundance was mainly affected by environmental factors such as temperature and current drift, herring abundance was positively affected by the recruitment of the neighboring stock of western Baltic spring spawners. One plausible explanation could be that sprat recruit to a more local component, while herring of the neighboring stock utilize the Skagerrak coastline as nursery grounds. This study demonstrates the importance of long time series and can provide new insight into the dynamics and structure of multiple fish species.

Temperature and wavelength drift tolerant WDM transmission and routing in on-chip silicon photonic interconnects.

We demonstrate a temperature and wavelength shift resilient silicon transmission and routing interconnect system suitable for multi-socket interconnects, utilizing a dual-strategy CLIPP feedback circuitry that safeguards the operating point of the constituent photonic building blocks along the entire on-chip transmission-multiplexing-routing chain. The control circuit leverages a novel control power-independent and calibration-free locking strategy that exploits the 2nd derivative of ring resonator modulators (RMs) transfer function to lock them close to the point of minimum transmission penalty. The system performance was evaluated on an integrated Silicon Photonics 2-socket demonstrator, enforcing control over a chain of RM-MUX-AWGR resonant structures and stressed against thermal and wavelength shift perturbations. The thermal and wavelength stress tests ranged from 27°C to 36°C and 1309.90 nm to 1310.85 nm and revealed average eye diagrams Q-factor values of 5.8 and 5.9 respectively, validating the system robustness to unstable environments and fabrication variations.

Posture algorithm for mobile robot based on ultrawide band

Inertial measurement unit or other navigation devices are used to obtain the posture information of most mobile robots based on ultrawide band. However, problems, such as zero drift, temperature drift, and error increasing with time, exist in inertial measurement unit and other navigation devices. To overcome these problems, a posture algorithm for mobile robot based on ultrawide band is proposed in this article. Real-time posture information can be obtained by the posture algorithm without using inertial measurement unit and other navigation devices. Simulated results show that the mean absolute error and root mean square error of posture angle in the global coordinate system are 0.951° and 1.169°, respectively. Both the simulated and experimental trajectories show good agreement with the ideal trajectory. The results indicate that the posture data can be obtained accurately by the posture algorithm and the accuracy can meet the requirements for most mobile robots. This article is expected to be of great guiding significance for the development of mobile robots.

Experimental demonstration of remotely controlled tunable optical correlators of 10–50 Gbaud QPSK channels using linear and nonlinear components and laser-delivered powers

We experimentally demonstrated two enabling architectures for remotely controlled optical quadrature-phase-shift-keying (QPSK) correlators based on both linear and nonlinear elements. The correlator site was located far from the transmitter site and had no access to the local optical power. In the first demonstration, a remote correlator based on a cascade of Mach–Zehnder interferometers (MZIs) was phase-controlled through optical power sent from the transmitter via an optical fiber link. The issue of power loss because of fiber nonlinearities was further addressed by monitoring and managing the backscattered power. In this manner, the power delivered through the link was boosted by ∼13 dB. Another ∼6 dB gain in the delivered power was obtained by adding a second source of light power. The correlator was shown to be able to identify different target patterns within incoming QPSK signals at different baud rates from 10 to 50 Gbaud. In the second architecture, we experimentally demonstrated a tunable optical correlator for a 10/15-Gbaud QPSK data signal using temperature-controlled nonlinear wave mixing at a remote node. A high-power pump was phase-modulated to overcome the link backscattering effect and was sent along with the signal copies to a remote correlator node through an optical fiber link. The waves generated at the output of the correlator were sent back to the transmitter for the monitoring of the operation. We showed a power boost of more than 3 dB for the correlated signal at a temperature drift of 2 °C. Using remote control and monitoring, improved constellation diagrams with lower error vector magnitudes (EVMs) for a temperature drift range of < 2 °C were obtained.

Characteristic analysis and motion control of a novel ball double-screw hydraulic robot joint

ABSTRACT The hydraulic joint is the key driving component of a robot. To reduce the joint size of the hydraulic robot, and improve the control accuracy and dynamic response performance, this paper proposes a novel joint structure and control method of a ball double-screw hydraulic robot. Using ball and circular arc spiral groove transmission, the hydraulic joint has a small transmission friction coefficient, compact overall structure and higher transmission accuracy. Aiming to resolve the problems of low control accuracy and motion instability caused by temperature drift in valve-controlled hydraulic systems, the high-precision joint control method based on adaptive fuzzy control compensation is used to improve the control accuracy and stability. The static and dynamic characteristics of the designed hydraulic joint are analyzed by simulation. A test platform was built, and the physical prototype of the hydraulic joint underwent static testing, dynamic control, amplitude frequency response and trajectory tracking tests. The experimental results were similar to the simulation results. The ball double-screw hydraulic robot joint has the characteristics of low starting pressure, high energy density, fast dynamic response, small amplitude frequency attenuation and high control accuracy. The starting pressure is 0.5 MPa, maximum swing frequency is 3 Hz, positioning accuracy is ± 0.03°, tracking accuracy is ± 3.9° and maximum angular velocity at 10 MPa is about 7.6 rad/s, which is close to the angular velocity of the actual human joint.

Application of Temperature Compensation Combined with Neural Network in Infrared Gas Sensor

Due to the state of the gas to be measured, the detection mechanism of the pyroelectric detector and the temperature drift of the peripheral circuit components and the detection of the ambient temperature will interfere with the measurement accuracy of the nondispersive infrared gas sensor from many aspects. This paper proposes a temperature compensation method based on the BP neural network. The compensation function of the gas sensor is realized by programming the various functional parameters in the neural network through the program provided in the Matlab neural network toolbox. Experimental simulation results show that the proposed method effectively reduces the influence of external temperature on the gas sensor output and improves its accuracy and stability.

A Method for Fiber Optic Gyroscope Temperature Drift Compensation Using Correlations between the Readings of the Gyroscope and Several Temperature Sensors

A Method for Fiber Optic Gyroscope Temperature Drift Compensation Using Correlations between the Readings of the Gyroscope and Several Temperature Sensors

Design of a precise current source with adjustable frequency for AC-FSM

AC-FSM is a new technology of external monitoring the internal corrosion for oil and gas pipelines. The current source stability of the FSM equipment is one of the important factors affecting the monitoring accuracy. According to the equipment requirements, a precision current source with adjustable frequency is designed. With C8051MCU as the control core, DAC conversion and differential amplifier are used to control the frequency and the current amount. The experiment shows that the output of excitation power supply has good consistency, the changing range was less than 0.3 %. When the temperature changes, under the condition of low frequency 5Hz, the change of current is less than 0.5 %, under the condition of high frequency 102Hz, the change of current is less than 0.4 %, which avoids the influence of temperature drift. This equipment is suitable for the long period operation of oil and gas pipelines in the field.

Characterization and compensation of thermal bias drift of a stiffness-tunable MEMS accelerometer

This paper presents characterization and compensation of the thermal bias drift of a MEMS accelerometer whose effective stiffness is electrostatically tuned to a low value with the help of the single-sided parallel plates (SSPPs) capacitors. A temperature drift model for the proposed accelerometer is built and the temperature effect on the mechanical stiffness and the circuit gains is characterized. The characterization reveals that the variations of the feedforward coefficient including the mechanical stiffness and the readout gain due to the temperature change play a significant role in the bias drift of output of the proposed closed-loop accelerometer. On the other hand, the variations of both feedback gain and tuning gain as a function of temperature are one-order-of-magnitude less than that of the feedforward coefficient. To calibrate the feedforward coefficient, an excitation signal as a form of AC reference displacement is introduced to drive the proof mass and the readout response is demodulated to calibrate the variance of the feedforward coefficient correspondingly. An open-loop compensation scheme for the temperature-induced bias drift using the variance of the calibrated response is proposed accordingly. Alternatively, the calibrated response can be controlled to a preset value by a new proportion integral derivative (PID) controller by the adjustment of the SSPP tuning voltage. The output of the PID controller is used for the calibration of the introduced bias from the electrostatic tuning force. Therefore, a closed-loop compensation of the thermal bias drift is achieved by remaining the feedforward coefficient while eliminating the calibrated bias. Experiments under a temperature cooling process and different tuning voltages are carried out to verify two proposed compensation schemes. The temperature drift coefficients (TDCs) of both compensated outputs exhibit at least one-order-of-magnitude reduction in response to the temperature change. When the effective stiffness of the accelerometer is tuned to about 4.19 N m−1, the TDC of the compensated output using the proposed open-loop or closed-loop compensation schemes is reduced to about 0.1136 or 0.0391 mg °C−1, respectively and meanwhile, the Allan bias instability is slightly increased to 48.63 or 56.14 μg, respectively.

A Novel Temperature Drift Error Precise Estimation Model for MEMS Accelerometers Using Microstructure Thermal Analysis.

Owing to the fact that the conventional Temperature Drift Error (TDE) precise estimation model for a MEMS accelerometer has incomplete Temperature-Correlated Quantities (TCQ) and inaccurate parameter identification to reduce its accuracy and real time, a novel TDE precise estimation model using microstructure thermal analysis is studied. First, TDE is traced precisely by analyzing the MEMS accelerometer’s structural thermal deformation to obtain complete TCQ, ambient temperature T and its square T2, ambient temperature variation ∆T and its square ∆T2, which builds a novel TDE precise estimation model. Second, a Back Propagation Neural Network (BPNN) based on Particle Swarm Optimization plus Genetic Algorithm (PSO-GA-BPNN) is introduced in its accurate parameter identification to avoid the local optimums of the conventional model based on BPNN and enhance its accuracy and real time. Then, the TDE test method is formed by analyzing heat conduction process between MEMS accelerometers and a thermal chamber, and a temperature experiment is designed. The novel model is implemented with TCQ and PSO-GA-BPNN, and its performance is evaluated by Mean Square Error (MSE). At last, the conventional and novel models are compared. Compared with the conventional model, the novel one’s accuracy is improved by 16.01% and its iterations are reduced by 99.86% at maximum. This illustrates that the novel model estimates the TDE of a MEMS accelerometer more precisely to decouple temperature dependence of Si-based material effectively, which enhances its environmental adaptability and expands its application in diverse complex conditions.

A study of effect factors on thermal drift rates during cryogenic indentation via Taguchi design and finite element method

Although nanoindentation at cryogenic temperatures has been widely used to evaluate mechanical deformation behaviors and damage mechanism, thermal drift has a significant effect on accuracy and reliability of measurements. In order to acquire high-quality data of indentation, this paper proposes a novel evaluation method on the significance of effect factors and their interactions for thermal drift rates during cryogenic indentation using a Taguchi robust design combined with finite-element analysis. The results of signal-to-noise (S/N) and analysis of variance (ANOVA) are indicated that the effects of the five control factors on the measurement of thermal drift are ranked as: specimen material > indenter tip assembly’s material > loading rate > testing temperature > peak of load. It demonstrates that temperature-dependent material properties for the contact pair are the most important factors in determining the thermal drift rate. Therefore, an upgraded indenter tip assembly with the Invar 36 shaft and the diamond tip is proposed for the cryogenic indentation of different materials. To further reduce thermal drift, an atmosphere pre-cooling method for tip assembly and specimen during cryogenic indentation is recommended owing to its minimum thermal drift and high homogeneity of temperature.

Model-Based Correction of Temperature-Dependent Measurement Errors in Frequency Domain Electromagnetic Induction (FDEMI) Systems.

Data measured using electromagnetic induction (EMI) systems are known to be susceptible to measurement influences associated with time-varying external ambient factors. Temperature variation is one of the most prominent factors causing drift in EMI data, leading to non-reproducible measurement results. Typical approaches to mitigate drift effects in EMI instruments rely on a temperature drift calibration, where the instrument is heated up to specific temperatures in a controlled environment and the observed drift is determined to derive a static thermal apparent electrical conductivity (ECa) drift correction. In this study, a novel correction method is presented that models the dynamic characteristics of drift using a low-pass filter (LPF) and uses it for correction. The method is developed and tested using a customized EMI device with an intercoil spacing of 1.2 m, optimized for low drift and equipped with ten temperature sensors that simultaneously measure the internal ambient temperature across the device. The device is used to perform outdoor calibration measurements over a period of 16 days for a wide range of temperatures. The measured temperature-dependent ECa drift of the system without corrections is approximately 2.27 mSm−1K−1, with a standard deviation (std) of only 30 μSm−1K−1 for a temperature variation of around 30 K. The use of the novel correction method reduces the overall root mean square error (RMSE) for all datasets from 15.7 mSm−1 to a value of only 0.48 mSm−1. In comparison, a method using a purely static characterization of drift could only reduce the error to an RMSE of 1.97 mSm−1. The results show that modeling the dynamic thermal characteristics of the drift helps to improve the accuracy by a factor of four compared to a purely static characterization. It is concluded that the modeling of the dynamic thermal characteristics of EMI systems is relevant for improved drift correction.

Study of the characteristics of the gamma spectrometer UDS-GCA-BGO for radiometric surveying

The calibration procedure of the gamma spectrometer UDS-HZ-BGO, created at the IPGG SB RAS, is formulated. The efficiency of the technique has been confirmed experimentally. Using the example of gamma-spectrometric studies of the territory of the IPGG SB RAS, the presence of a temperature drift of the device response caused by insufficient temperature compensation was recorded. The dependences of the change in the value of the measured content of radioactive elements U, Th, K at points on the territory of the IPGG on the ambient temperature in the range from plus 15 C to minus 20 C are obtained. The results are recommended to be used for temperature correction of element concentrations during radiometric survey.

Modeling and Design of Resonant Magnetic Field Sensors in the Scheme of Differential Magnetostrictive Actuation With Compact Bias Magnetic Circuit

A type of differential resonant magnetic field sensor is developed by employing the composite elements of FeGa plates, piezoelectric quartz crystal double-ended tuning forks (DETFs) and bias permanent magnets. The model and analysis show that the differential design brings the benefits of doubled sensitivity, increased linearity and low temperature drift. Importantly, a small and compact magnetic circuit containing a pair of permanent magnets and dual FeGa plates ensures the generation of differential actuation, which not only reduces the leakage flux but also improve the field-sensitivity and resolution. The magnetic circuit model based on the “lumped parameters” method is established. As an important aid, the distribution of magnetic flux density along the longitudinal direction of the FeGa alloy is simulated by finite element analysis software. In order to avoid the prediction error caused by parameter errors, simulations in different conditions are carried out for comparative analysis. This method ensures the magnetic circuit provides qualified magnetic field. The experimental results show that the differential resonant magnetic field sensor with frequency readout has the characteristics of high sensitivity of 4.4 Hz/Oe, high resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${&lt; }3.04\times 10^{-4}$ </tex-math></inline-formula> Oe, low temperature drift and excellent linear (non-linearity error of 1.3%FS) and low hysteresis (1.5%FS) over its measurement full scale (FS) of ±100Oe.

Nonlinear correction method of pressure sensor based on data fusion

Piezoresistive sensors are widely used in the design of underwater pressure transmitters, whose nonlinear output is easily affected by the temperature of oil and gas medium. Most of the published literature focuses on hardware, software, or hybrid correction methods, but they are inflexible, have low accuracy and large temperature drift, especially can not retain the nonlinear characteristics of the sensor itself. This paper presents a nonlinear correction method for pressure sensors based on data fusion. Firstly, the pressure and temperature coupling model is established by using ANSYS software, and the extra thermal stress caused by temperature is analyzed, which makes the pressure sensor have strong nonlinear. Secondly, a nonlinear correction method combining polynomial fitting, BP neural network activated by wavelet function, and BP optimization algorithm based on particle swarm optimization (PF-W_BP-PSO_BP) is proposed. This method combines the advantages of numerical calculation and machine learning, retains the nonlinear characteristics of sensor output and restrains the influence of temperature, and proves that this method is superior to the existing correction methods. Finally, pressure and temperature data acquisition experiments are designed, which verifies the scientific nature and effectiveness of the nonlinear correction method in this paper. The method has been applied to the development project of a pressure and temperature integrated transmitter 1500 m underwater, and its practicability has been verified.