Temperature Transducer Research Articles

Volumetric hydrogen sorption measurements – Uncertainty error analysis and the importance of thermal equilibration time

The design of a volumetric measurement apparatus is studied by means of an uncertainty analysis to provide guidelines for optimum hydrogen sorption measurements. The reservoir volume should be as small as possible (i.e., 10 cc) to minimize the uncertainty. In addition, the sample mass loading has a profound effect on the uncertainty and the optimum loading is a function of the sample's intrinsic storage capacity. In general, the higher the sample mass loading the lower the uncertainty, regardless of any other parameter. In cases where the material to be tested is not available in gram quantities, the use of high accuracy pressure and temperature transducers significantly mitigates the uncertainty in the sample's hydrogen uptake. Above all, the thermal equilibration time is an important parameter for high accuracy measurements and needs to be taken into consideration at the start of the measurements. Based on a computational analysis, a 5 min wait time is required for achieving thermal equilibrium when the instrument enclosure temperature is different than the ambient temperature.

Nonlinear Compensation Method for Transducer Based on Neural Network with Fourier Functions

Aiming to solve the problems in the non-linearity of thermistor temperature transducer, a compensate model based on neural network (NN) is proposed. The basic idea is using Fourier series as the basic functions of NN，the output of transducer as input samples of NN and the temperature as the expectation output of NN. The output of NN is used to approximate to the measured temperature by adjusting the weights. The results show the proposed method is effective in raising accuracy.

Modeling of Ultrasonic Measurement Systems with Waveguides

The ultrasonic pulse-echo technique is used for non-intrusive process monitoring. The material properties must be investigated in very complicated conditions - high temperature and others. The special high temperature transducers or waveguides must be used to protect the transducer from the high temperature of the material. Objective of this work was comparison of the two modeling techniques of the ultrasonic waveguides for application of the ultrasonic measurements: 1D matrix technique and 2D finite element method. Ill. 9, bibl. 9, tabl. 1 (in English; abstracts in English and Lithuanian).DOI: http://dx.doi.org/10.5755/j01.eee.123.7.2375

Design and Development of a Novel Passive Wireless Ultrasensitive RF Temperature Transducer for Remote Sensing

A wireless, passive, and ultrasensitive temperature transducer is presented in this paper. The transducer consists of split ring resonators loaded with micro-bimorph cantilevers, which can potentially operate up to millimeter-wave frequencies (above 30 GHz). As the temperature changes, the bimorph cantilevers deflect and result in a shift of the resonant frequency of the split rings. A design is proposed, that has a maximum sensitivity of 2.62 GHz/μm, in terms of frequency shift per deflection unit, corresponding to a sensitivity of 498 MHz/°C for an operating frequency around 30 GHz, i.e., a frequency shift of 1.6% per °C. Theoretically, it's about two orders of magnitude higher than the existing sensors observed in the same class. This sensor design also offers a high Q factor and is ultra-compact, enabling easy fabrication and integration in micro-electromechanical systems technology. Depending on the choice of materials, the proposed designs can also be utilized in harsh environments. As a proof of concept, a prototype is implemented around 4.7 GHz which exhibits a frequency shift of 0.05%/°C, i.e., 17 times more sensitive than the existing sensors.

Long-Term Outdoor Reliability Assessment of a Wireless Unit for Air-Quality Monitoring Based on Nanostructured Films Integrated on Micromachined Platforms

We have fabricated and tested in long-term field operating conditions a wireless unit for outdoor air quality monitoring. The unit is equipped with two multiparametric sensors, one miniaturized thermo-hygrometer, front-end analogical and digital electronics, and an IEEE 802.15.4 based module for wireless data transmission. Micromachined platforms were functionalized with nanoporous metal-oxides to obtain multiparametric sensors, hosting gas-sensitive, anemometric and temperature transducers. Nanoporous metal-oxide layer was directly deposited on gas sensing regions of micromachined platform batches by hard-mask patterned supersonic cluster beam deposition. An outdoor, roadside experiment was arranged in downtown Milan (Italy), where one wireless sensing unit was continuously operated side by side with standard gas chromatographic instrumentation for air quality measurements. By means of a router PC, data from sensing unit and other instrumentation were collected, merged, and sent to a remote data storage server, through an UMTS device. The whole-system robustness as well as sensor dataset characteristics were continuously characterized over a run-time period of 18 months.

The Basic Study of Ultrasound Characteristics and Velocimetry in Molten Glass

High temperature measurement system is presented. This system employs the ultrasonic buffer rod and pulsed Doppler method. The buffer rod has a cooling jacket to use the high efficiency room temperature transducer. For considering ultrasonic velocimetry method in the molten borosilicate glass, the temperature dependency of sound velocity at the temperature of 1000°C to 1200°C is obtained using cross-correlation technique, and its difference is within plus-minus 5%. A numerical simulation is also applied to design the optimised buffer rod, and its result shows good agreement with an experiment. Using this technique, the velocity, especially the speed of relative moving wall is obtained, and its error is within plus-minus 4% when a value remained in measurable velocity.

Temperature maps measurements on 3D surfaces with infrared thermography

The use of the infrared camera as a temperature transducer in wind tunnel applications is convenient and widespread. Nevertheless, the infrared data are available in the form of 2D images while the observed surfaces are often not planar and the reconstruction of temperature maps over them is a critical task. In this work, after recalling the principles of IR thermography, a methodology to rebuild temperature maps on the surfaces of 3D object is proposed. In particular, an optical calibration is applied to the IR camera by means of a novel target plate with control points. The proposed procedure takes also into account the directional emissivity by estimating the viewing angle. All the needed steps are described and analyzed. The advantages given by the proposed method are shown with an experiment in a hypersonic wind tunnel.

Near-Infrared Absorption of Monodisperse Silver Telluride (Ag2Te) Nanocrystals and Photoconductive Response of Their Self-Assembled Superlattices

Monodisperse 3.1 nm Ag2Te NCs show a sharp optical absorption feature at 1154 nm with a large linear temperature dependence and the photoconductive response consistent with semiconducting character in Ag2Te NCs. The wavelength of the resonance is within the window of transparency for biological tissue making it a potential in vivo temperature marker or transducer for in situ heating with deep-penetrating near-infrared radiation.

The glazing temperature measurement in solar stills – Errors and implications on performance evaluation

Although the brine temperature measurement in solar stills would be more or less conventional, the precise condensing surface temperature measurement, appears to present a significant difficulty to measure. In the present investigation, an analysis is developed aiming to underline the parameters affecting the glazing surface temperature measurement and a series of field measurements are presented, aiming to identify and evaluate the errors associated to the measurement of this crucial physical quantity. It is derived that among other reasons the surface temperature measurement accuracy may strongly be degraded owing to the sensor tip overheating due to the radiation absorption, as well as to the development of poor bond conductance between sensor bead and glazing surface. It may also be degraded owing to the temperature drop across the glazing thickness and the non-uniform temperature distribution over the entire condensing surface area, something that makes the selection of the appropriate location of the particular temperature transducer necessary. Based on the derived measurements, an order of magnitude analysis is employed for the approximate evaluation of error range in the condensing surface temperature measurement. This, which depending on specific conditions was found to vary between about 1 and 2 °C, was employed to demonstrate the implications and approximate conditions under which its effect could become excessively high in ordinary solar still investigations.

Experimental Investigation of Two-Phase-Flow Patterns and Hydraulic Performance of Electrical Submersible Pumps

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper CSUG/SPE 134089, ’Experimental Investigation on the Viscous Effect on Two-Phase Flow Patterns and Hydraulic Performance of Electrical Submersible Pumps,’ by F.E. Trevisan, SPE, and M.G. Prado, SPE, University of Tulsa, originally prepared for the 2010 Canadian Unconventional Resources & International Petroleum Conference, Calgary, 19-21 October. See Journal of Canadian Petroleum Technology, April 2011, page 45. Using a visualization prototype built from original electrical-submersible-pump (ESP) components and with minimal geometrical modifications, an experimental procedure was developed and conducted to address the viscous effect on liquid/gas two-phase flow through ESPs. On the basis of dimensionless groups that govern centrifugal-pump single-phase performance, two-phase experiments were conducted at different shaft speeds, nonslip void fractions, and viscosity values while liquid rates were kept constant at 60% of the maximum rate at the defined shaft speed. Introduction An ESP is one of the many existing artificial-lift techniques used in the petroleum industry. It consists of a series of small-diameter diffuser-type casing centrifugal pumps, mainly known for their capacity for handling high volumes. Their applications vary from producing high-productivity oil wells onshore and offshore to dewatering coalbed-methane and gas wells. The use of ESPs in liquid single-phase applications is well understood. However, the presence of a compressible phase, such as natural gas, will modify the hydraulic performance of this type of pump. The presence of a second phase often will degrade the ability of the pump to deliver pressure, and depending on the amount of gas flowing through the system, instabilities may occur. These, also referred to as surging, eventually lead to extremely low pressure generation, also known as gas lock. Experimental Description An ESP visualization prototype was designed, built, and installed in a closed-circuit loop. Fig. 1 in the full-length paper provides a graphical representation of the experimental facility. This closed circuit consisted of a 65-gal tank to store the liquid, from which the fluid passed through a booster pump and a liquid-measuring unit before flowing to the ESP prototype. Air was provided by a 1-hp compressor delivering pressures up to 10 psig and flow rates up to 10 scf/hr. Gas was injected at the liquid line close to the prototype intake and measured by rotameters. After passing through the ESP prototype, the fluids returned to the liquid storage tank that also acted as an open-air separator. Both ESP and booster-pump motors were controlled by individual variable-speed drives linked to the acquisition system. This system also received information the differential-pressure and temperature transducers.

Monitoring of injection molding of thermoplastics: Average solidification pressure as a key parameter for quality control

The quality of the molded parts depends on the processing conditions, which creates a continuous demand for advanced techniques for monitoring and controlling the process. Temperature and pressure transducers are being used increasingly in industry. Therefore, the use of their measurements to obtain indications concerning the product quality could overcome the traditional resistance of industry to introduce new sensors in their production. The aim of this paper was to select a parameter, which can be identified by adopting pressure and temperature transducers, to correlate with the quality. To this goal, several series of injection molding tests were conducted by adopting a general purpose PS, changing the holding pressure and time, injection time, mould and injection temperature, nozzle length, gate and cavity thickness. The pressure histories and temperature evolution at the interface with the mould at several positions along the flow-path were measured by means of pressure-temperature transducers. The samples were measured after molding, and dimensional accuracy was assumed to be the target quality parameters. The mean solidification pressure, namely the average along the thickness direction of the pressures at which each layer solidifies, is a key parameter for quality control. A procedure not requiring simulation of the entire injection molding test and based on the knowledge of both the local pressure evolution, mold temperature and the polymer thermal diffusivity has been developed to evaluate the local solidification profile.

Use of a data measurement system for studying the characteristics of temperature sensors

The 3 C bench was developed to study the characteristics of the temperature transducers widely used in chemical fibre production. The transient responses of temperature sensors were investigated to select the optimum temperature in the texturing machine for control. The partial dynamic characteristics can be used to determine the maximum sampling period of the measurement system temperature transducers which provide for the given accuracy. The studies of signal filtration of the measurement data obtained from the temperature sensors conducted in the Matlab system allowed more substantiated establishment of the parameters of the filters in the DMS measuring channel.

Development of optical fiber-based respiration sensor for noninvasive respiratory monitoring

In this study, two types of nasal-cavity-attached fiber-optic respiration sensors have been fabricated for noninvasive respiratory monitoring. One is a silver halide optical-fiber-based respiration sensor that can measure the variations of infrared radiation generated by the respiratory airflow from a nasal cavity. The other is a thermochromic-pigment-based fiber-optic respiration sensor that can measure the intensity of reflected light which changes owing to color variations of the temperature-sensing film according to the temperature difference between inspiratory and expiratory air. We have demonstrated the similarities of the respiratory signals using the fiber-optic respiration sensors and the temperature transducer of the BIOPAC® system. In addition, we verified that respiratory signals without the deterioration of the MR image can be obtained using the fiber-optic respiration sensors. It is anticipated that the proposed noninvasive fiberoptic respiration sensors will be highly effective for respiratory monitoring of a patient during MRI procedures.

High temperature ultrasonic transducer up to 1000 °C using lithium niobate single crystal

Structural health monitoring (SHM) techniques are needed to maintain the reliability of aging power plants. The high temperature transducers are necessary to realize SHM under the working condition of power plants. In this paper, a high temperature transducer was developed using lithium niobate (LiNbO3) single crystal, which is well known as a high Curie temperature piezoelectric material. The LiNbO3 was bonded onto a stainless steel substrate. The transducer was heated in an electric furnace while measuring the bottom echoes from the substrate. We confirmed that the high temperature transducer could work up to 1000 °C.

The Effect of Ga3+ Substituting Sc3+ on Properties of BiScO3-PbTiO3 Ceramics

0.36(BiSc(1-x)Ga x O3)-0.64PbTiO3(BGSPT64-x, x = 0.001, 0.003, 0.005, 0.008, 0.01, 0.015, 0.02) solid solutions were prepared by conventional solid state reaction method. The results of x-ray diffractions revealed that the introduction of the Ga didn't change the perovskite structure of the solid solutions. The dielectric and piezoelectric properties were investigated. The results showed that BGSPT64-0.01 had an optimized characterization and its piezoelectric coefficient d 33, planar coupling coefficient k p, remnant polarization p r and the coercive field Ec are 510 pC/N, 61%, 49μC/cm2 and 2.1kv/mm, respectively. The BGSPT64-0.01 ceramics will be a good candidate material for the high temperature piezoelectric actuator and transducers.

A new three-dimensional heat flux–temperature integral relationship for half-space transient diffusion

Abstract This paper derives a new integral relationship between heat flux and temperature in a transient, three-dimensional heat conducting Cartesian half space ( x > 0 , y ∈ ( − ∞ , ∞ ) , z ∈ ( − ∞ , ∞ ) ). A unified mathematical treatment has been developed based on operational and transform methods; and singular integral equation regularization. Regularization is accomplished based on a series of observations involving the diffusive nature of the operator. This newly developed relationship provides the local heat flux perpendicular to the front surface at any location within the half space. This expression suggests that an embedded plane of temperature sensors parallel to the surface can be used to acquire the local, in-depth heat flux in the x -direction. The relationship does not require a priori knowledge of the surface boundary condition which has analytically been removed in the process. The ill-posed nature of diffusion is highlighted owing to the appearance of the heating/cooling rate (°C/s) in the integrand of the new relationship. Integral relationships of this type are highly useful for experimental investigations since the in-depth heat flux can be extracted from well-established temperature transducers.

Temperature-Compensated Cone Penetration Test Mini-Cone Using Fiber Optic Sensors

Abstract The mechanical properties obtained by using a strain gauge are influenced by the temperature change that occurs due to the electrical resistance change of the strain gauge and cable. The temperature change, which occurs during cone penetration testing, can produce an unreliable cone tip resistance. Several types of cone penetrometers with diameters ranging from 1 to 7 mm are developed by using fiber Bragg grating (FBG) sensors for the temperature compensation. The design concerns include the configuration, active and temperature sensor installation, and calibration. FBG active sensors monitor both the tip resistance and the temperature change, while the FBG temperature transducer only measures the temperature change. The experimental studies show that the tip resistance estimated by strain gauges is affected by the temperature change in both full and half Wheatstone bridges, but the tip resistance determined by the FBG sensors is independent of the temperature change. The tip resistances determined by the strain gauges and the FBG sensors are reliable after the temperature is compensated for. This study demonstrates that by using FBG sensors, cone penetrometers produce a more reliable cone tip resistance.

Automated bench based on the NI USB-6009 data acquisition board for measuring static parameters micromechanical thermistor converter

The hardware architecture, software and user’s interface of the automated stand for determination of static parameters of resistive temperature transducer are described. The structure of directly and indirectly heated micromechanical resistive membrane element and its basic parameters are specified. The measured with the designed stand transducer’s characteristics are presented and analyzed

Instrumentation system for improvement of temperature sensor performance

The semiconductor resistances known as thermistors have more advantages compared with all other temperature transducers. Unfortunately, the non-linear characteristics, lower sensitivity for the higher temperature range of measurement and the self-heating effect of thermistors are some of their disadvantages that are limiting their application. As a result of some intensive research on improvement of the measurement and instrumentation techniques with thermistors, an electronic circuit is developed that is reducing considerably the thermistor non-linearity, its self-heating effect and is increasing its sensitivity in a wider temperature range of measurements and control. The circuit involves a set of thermistors, connected in a specific Wheatstone-bridge configuration. Analysis of the circuit and testing it in real environment proves its effectiveness in improvement the performance of this temperature sensor equipment. Keywords: Sensors, Transducers, Thermistors, Characteristics, Stable, Linearity, Self-heating, Sensitivity, Range, Measurement, Wheatstone bridge

A Real-Time Thermal Model of a Permanent-Magnet Synchronous Motor

This paper presents a real-time thermal model with calculated parameters based on the geometry of the different components of a permanent-magnet synchronous motor. The model in state-space format has been discretized and a model-order reduction has been applied to minimize the complexity. The model has been implemented in a DSP and predicts the temperature of the different parts of the motor accurately in all operating conditions, i.e., steady-state, transient, and stall torque. The results have been compared with real measurements using temperature transducers showing very good performance of the proposed thermal model.