Simultaneous Measurement Of Temperature Research Articles

Signal processing integrated with fiber-optic Vernier effect for the simultaneous measurement of relative humidity and temperature.

A novel inline Fabry-Perot interferometer (FPI) for simultaneous relative humidity (RH) and temperature monitoring is proposed. The sensing probe consists of a section of hollow core Bragg fiber (HCBF) spliced with a single-mode fiber pigtail. The end-face of the HCBF is coated with Chitosan and ultraviolet optical adhesive (UVOA), forming two polymer layers using a well-designed fabrication process. The surfaces of the layers and splicing point will generate multiple-beam interference and form Vernier-effect (VE) related envelopes in the reflection spectrum. A signal processing (SP) method is proposed to demodulate the VE envelopes from a complicated superimposed raw spectrum. The principle of the SP algorithm is analyzed theoretically and verified experimentally. The sensor's RH and temperature response are studied, exhibiting a high sensitivity of about 0.437 nm/%RH and 0.29 nm/ ∘C, respectively. Using a matrix obtained from experiment results, the simultaneous RH and temperature measurement is achieved. Meanwhile, the simple fabrication process, compact size and potential for higher sensitivity makes our proposed structure integrated with the SP algorithm a promising sensor for practical RH and temperature monitoring.

Machine learning approach with higher accuracy for simultaneous measurement of the dual parameter by MSM fiber structure

In this paper, a novel and efficacious method for simultaneous measurement of temperature and strain by employing a multi-single-multi mode (MSM) fiber segment using an Artificial Neural network (ANN) has been reported and studied. An experiment is performed to accumulate the input dataset and employed in the ANN model for training and testing thoroughly. Captivating performance in terms of different metrics has been illustrated. The results ensure that our proposed model has attained enhancement in the root mean squared error (RMSE) of 1294 times and 301 times in comparison with the transfer matrix method for measuring the temperature and strain respectively. Furthermore, higher sensitivities are achieved using the proposed techniques. These primary findings suggest that the proposed scheme could be employed for various multiparameter sensing applications with enhanced performance capabilities.

LMAP-09 RECAPITULATING LASER INTERSTITIAL THERMAL THERAPY IN PRECLINICAL BRAIN TUMOR MODELS

Abstract Laser interstitial thermal therapy (LITT) is a minimally-invasive option for cytoreduction of recurrent or otherwise difficult-to-access intracranial tumors. Relative to resection, ablated tumor tissue remains in situ, facilitating recognition of tumor antigens and a targetable immune response. To investigate the immune consequences of LITT, we developed a model of stereotactic laser ablation for use with existing syngeneic glioma and intracranial metastasis cell lines. A 1064 nm diode-based Nd:YAG laser (Monteris Medical) was used to thermally ablate normal brain tissue or CT-2A tumors in C57BL6/J mice. Ablations were performed at 10 days post-implantation at + 2 ML, + 1 AP, -3 DV using a stereotactic frame. Simultaneous temperature measurements were taken using a thermocouple probe implanted to the same depth 2 mm posterior. We first used serial T2-weighted MRI imaging to accurately track the tumor growth characteristics and identify a safe lesion size for ablation, selecting 10 days post-implantation for subsequent experiments and 2 mm posterior as the ideal position to monitor temperature at the lesion edge. To assess the thermal characteristics of our laser, we ablated mouse brains at 1 W and 2 W for 30, 60, or 90 seconds each, finding that 1 W for 90 seconds produced an ablation that did not char or coagulate tissue outside the ablation zone and recapitulated human ablation findings on H&E staining 24h post-LITT. We next implanted CT-2A tumors for ablation with the selected dose, following mice for survival between the LITT and sham-ablated groups. A subset of mice were imaged using T2-MRI at 1, 3, 7, and 14 days post-surgery. Our model recapitulates the essential clinicopathological findings of LITT and is well suited apply to a variety of intracranial tumor models and LITT-adjunctive therapies.

Simultaneous Measurement of Temperature and Pressure Based on Forward Brillouin Scattering in Double-Coated Optical Fiber

A novel method for simultaneous measurement of temperature and pressure based on forward Brillouin scattering (FBS) in double-coated optical fiber is proposed. A new phenomenon, which is the linear relationship between frequency shift of the FBS spectra induced by radial acoustic modes and pressure surrounding the sensing fiber, is theoretically analyzed and experimentally verified. Another new interesting feature is observed that the frequency shift-pressure coefficients of different radial acoustic modes are different. Based on the phenomena that different radial acoustic modes have different frequency shift-temperature and frequency shift-pressure coefficients, we propose a brand-new method to achieve the simultaneous measurement of temperature and pressure by using the frequency shift information of two FBS scattering peaks. In a proof-of-concept experiment, a double-coated single-mode fiber is used as the sensing fiber, and the temperature and pressure measurement errors are 0.13 °C and 0.05 MPa, respectively. The proposed method is expected to become a simple, accurate, durable and stable sensing method for simultaneously measuring temperature and pressure, which has great potential in many practical applications.

Experimental Study on Simultaneous Measurement of Temperature and Pressure of Seawater Based on the Reflecting Polarization Interferometer Incorporated With Bow-Tie Fiber

Detection of simultaneous measurement of temperature and pressure of seawater is very meaningful in oceanography research. To realize the goal, the reflecting polarization interferometer incorporated with the bow tie fiber is proposed. First, the formation of birefringence in the bow tie fiber and the working principle of the sensor are studied. Then, the temperature and pressure sensing experiments are performed, respectively. The least square method is adopted to eliminate the crosstalk influence. The best temperature and pressure sensitivities after adjustment are -1.2349nm/°C and 1.9209nm/MPa, respectively. The sensitivity matrix is built by extracting the information of two dips in the spectra. After comparison between the sensor demodulated results and the CTD measured data, the correlation coefficient (r), the mean absolute error (MAE), the mean absolute percentage error (MAPE), and the root mean square error (RMSE) of temperature are 0.9984, 0.3789°C, 1.18%, 0.4365°C, respectively, and r, MAE, MAPE, and RMSE of pressure are 0.9982, 0.0266MPa, 3.18%, and 0.0308MPa, respectively. So the method is verified to be accurate and feasible. This work could provide reference to who does oceanography research, and is very prospective in the field of ocean detection.

Simultaneously Monitoring Humidity and Temperature Based on Waveguide Bragg Grating Sensor Chip

Herein, we proposed and demonstrated a novel relative humidity (RH) sensing chip with temperature compensation, which is based on waveguide Bragg grating (WBG) assisted with polyvinyl alcohol (PVA) and polydimethylsiloxane (PDMS) composite film. Half of the cladding of the WBG region was corroded with hydrofluoric acid, which results in a split of the Bragg peak into two peaks. The PVA-PDMS composite film coated on the surface of the corroded region shows a high sensitivity to RH due to the hydrophilic hydroxyl groups of PVA film. PDMS not only enhances the stability of the composite film, but also reduces the RI of the PVA film, which restricts the energy loss of the light passing through. In our experiment, average RH sensitivities of -12.2 pm/RH% and 0 pm/RH% in the RH range of 50%-90%, and temperature sensitivities of 9.6 pm/°C and 9.8 pm/°C were obtained by the two peaks shift, respectively. We testified that the simultaneous measurement of RH and temperature can be achieved by the sensitivity matrix method. Furthermore, the proposed sensor possesses remarkable stability and excellent repeatability. Such a cost-effective, integrated, easily fabricated, and reflection power detection-based humidity sensor promises great application prospects in the fields of agriculture, food industry, biological field and other production activities.

Absolute calibration of a streaked optical pyrometer at nanosecond time scale with a luminescent concentrator

The Streaked Optical Pyrometer (SOP) is a visible diagnostic widely used to study the warm dense matter regime at high energy laser facilities, gas guns, or ion accelerators. It is usually coupled with a Velocity Interferometer System for Any Reflector (VISAR) diagnostic for simultaneous shock wave velocity, reflectivity, and temperature measurements to study the Equation of State (EOS) of materials. While VISAR is a well-mastered technology that provides velocity measurements with low relative uncertainties (close to percent), SOP diagnostics still suffer from high imprecision. In this article, we present a new calibration method in order to obtain absolute temperature measurements with reduced uncertainties. This approach is based on a novel light source: a Ce:YAG luminescent concentrator pumped by LEDs. This device produces enough optical power for calibration at the nanosecond sweep duration of the streak camera. As a demonstration, it has first been installed at the LULI facility and tested on quartz samples shocked at temperatures above 4000 K.

Experimental and numerical study on the falling film flow process on the outer wall of dome cylinder

The passive containment cooling system (PCCS) is crucial for ensuring the safety of nuclear power plants, and the thickness and temperature of the falling film on its outer wall are important parameters that determine the heat and mass transfer performances. In this paper, a compact liquid film thickness and temperature simultaneous measurement system was developed to provide a measurement method, which is based on the absorption spectroscopy technology, and then the measurement accuracy was verified by using a calibration tool. The results showed that the mean relative error of the liquid film thickness and temperature measurements from the known values were about 3.4% and 0.4%, respectively. On this basis, this system was used to study the falling film process on the outer wall of the dome cylinder analogous to the containment under different working conditions and combined with numerical simulation for comparison. The results showed that the two methods have good consistency. The variation of the liquid film heat transfer coefficient for various operating conditions was further analyzed. It was found that the average thickness of the falling film is positively correlated with the liquid flow rate, but negatively correlated with the temperature and heat transfer coefficient. In summary, this system can accurately study the falling film process on the outer wall of the dome cylinder, which is expected to accurately analyze the heat and mass transfer process in the PCCS and provide data support for its design and optimization.

Transfer-learning-based multi-wavelength laser sensor for high fidelity and real-time monitoring of ambient temperature and humidity.

Multi-wavelength laser absorption spectroscopy has the advantages of superior sensitivity, accuracy, and robustness for gas sensing applications, offering an opportunity for the development of high-performance laser-based hygrothermographs. However, accurate and fast determination of gas parameters from multiple spectral features can be quite challenging in the presence of large numbers of features, measurement noise, and increasing demands for real-time measurements. To address this challenge, we propose a transfer-learning-based multi-wavelength laser absorption sensor for the quantitative and simultaneous measurement of temperature and concentration of water vapor, with a focus on real-time monitoring of ambient temperature and relative humidity (RH). A spectral simulation based on the most-updated HITRAN database was employed as the dataset for model pre-training and transfer learning. The experimental dataset was obtained from absorption measurements using a distributed feedback laser that probed multiple water absorption features within the band of 7179-7186c m -1. To evaluate the sensor performance, mean absolute error, error distribution, and linearity were selected. In the presence of an insufficient experimental dataset for direct data training, the proposed transfer learning approach outperformed the traditional deep learning method with a lower prediction error of 0.14°C and 0.42% for temperature and RH, respectively, as compared to the values of 0.84°C and 0.66% obtained using the traditional deep learning method. Finally, the fast data post-processing performance of the proposed transfer learning approach was demonstrated in a field test against the conventional baseline fitting method.

Health Risk Assessment and Covid-19 Infection Rate by Using Bacterial Aerosol in Healthcare Workers in a Tertiary Care Hospital in Thailand During SARS-CoV-2 Pandemic

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide transmission and healthcare worker is the risk group. Therefore, the infection rate and health risk assessment from exposure to airborne transmission for healthcare workers were performed. Methods: This cross-sectional study was carried out on 106 healthcare workers at four selected service areas in Songklanagarind Hospital, Thailand, from February to September 2021. The N6 impactor was used with simultaneous measurement of temperature, relative humidity, and wind speed. The general characteristics of subjects and hospitals were collected by questionnaire and presented by descriptive statistics. Results: Most of the participants were female and they worked more than 8 hours per day. The bacteria concentration was highest in the Pediatric Outpatient Department (1837.46±177.52 cfu/m3). The lowest chronic daily intake and hazard quotient with no threshold (4.86±3.81, 95%CI: 3.59, 6.13) were at Covid-19 Intensive Care Unit - due to negative pressure ventilation in this room was effective in reducing the airborne concentration of the pathogens. Overall, the hospital’s hazard index with no threshold (30.87±35.25, 95%CI: 23.91, 37.83) was higher than 1.0, indicating that bacterial bioaerosol may affect healthcare workers’ health. The highest confirmed Covid-19 case was at Acute Respiratory Infection Clinic (19.29±10.67 cases/week). The probability of infection by SARS-CoV-2 in healthcare workers was high at Acute Respiratory Infection Clinic (1.0) and Covid-19 Intensive Care Unit (0.998±0.002, 95%CI: 0.998, 0.999). Conclusion: Therefore, inhalation reference concentration for hospitals should be as low as possible and appropriate ventilation systems should be implemented with adherence to standards to protect healthcare workers.

Polished hollow core Bragg fiber sensor for simultaneous measurement of cortisol concentration and temperature.

Disturbance of surrounding temperature inevitably affects the accuracy of fiber biosensors. To that end, we propose a compact label-free optofluidic sensor based on a polished hollow core Bragg fiber (HCBF) that can simultaneously measure the cortisol concentration and surrounding temperature in real-time. The sensor is comprised of fusion splicing single mode fiber (SMF), multimode fiber (MMF) and HCBF. HCBF is side polished to remove part of the cladding that the suspended inner surface of the fiber can contact the external environment. After the incident light passes through the MMF from the SMF, it enters the hollow area, high refractive index (RI) layers, respectively, where the anti-resonant reflecting optical waveguide (ARROW) guiding mechanism and Mach-Zehnder interferometer (MZI) are simultaneously excited. Taking advantage of the high RI layers of HCBF, compared to the fiber with uniform cladding, the light can be more confined in the cladding and more sensitive to inner surface medium. The inner surface of sensor is immobilized with cortisol aptamer for the sake of achieving high sensitivity and specific sensing of cortisol with the limit of detection (LOD) to be 4.303 pM. The proposed sensor has a compact structure, enables temperature compensation, and can be fabricated at low cost making it highly suitable for in-situ monitoring and high-precision sensing of cortisol and other biological analytes.

An Ultrafine No-Core Fiber-Based Sensor for Simultaneous Liquid Level and Temperature Measurement

An Ultrafine No-Core Fiber-Based Sensor for Simultaneous Liquid Level and Temperature Measurement

Composite Fabry-Perot interferometric gas pressure and temperature sensor utilizing four hole fiber with sensitivity boosted by high-order harmonic Vernier effect.

It is an enormous challenge for optical fiber sensors to intuitively achieve the simultaneous measurement of both gas pressure and temperature with high sensitivity. To address this challenge, the Fabry-Perot interferometer (FPI) based on high-order harmonic Vernier effect is combined with the fiber Bragg grating (FBG). A novel fiber sensor built with a cascaded FPI and an FBG for the simultaneous measurement of gas pressure and temperature is designed and experimentally investigated by virtue of the temperature sensing property of FBG and its independence on gas pressure-induced refractive index change, where a high-order harmonic Vernier effect was utilized to boost the gas pressure sensitivity of the sensor. As gas pressure increases from 0 to 1 MPa, the internal envelope of composite FBG and FPI based 10-order harmonic Vernier effect exhibits redshift with maximal sensitivities of 146.64 nm/MPa and a high magnification factor of 43. FBG is insensitive to gas pressure change, whereas, the spectral response of the internal envelope 10-order harmonic Vernier effect and FBG monotonously move and undergo blueshift and redshift as the temperature increases from 30 °C to 120 °C with maximal sensitivities of -0.48 and 0.011 nm/°C, respectively. Therefore, the distinct sensitivities of FBG and FPI to gas pressure and temperature result in extraction of both gas pressure and temperature information simultaneously by constructing measurement matrixes.

A hybrid interferometer sensor for simultaneous measurement of temperature and gas pressure based on tapered seven-core fiber and PDMS

A novel hybrid interferometer sensor composed of a tapered seven-core fiber (TSCF) and a polydimethylsiloxane (PDMS) cap at the end face of a TSCF is proposed for simultaneous measurement of temperature and gas pressure. TSCF forms a Michelson interferometer (MI), and the PDMS cap on the end surface of TSCF forms a Fabry–Pérot interferometer (FPI). The sensing head consisted of a cascade of MI and FPI. When the external temperature or gas pressure changes, owing to the thermal effect or elastic deformation of PDMS, the interference spectrum of the FPI shifts significantly, so the FPI is very sensitive to temperature and gas pressure. MI, which is made of quartz optical fiber, is sensitive only to temperature and is not to gas pressure. The experimental results show that FPI has a temperature sensitivity of −0.22 nm °C−1 in the temperature range of 40 °C–80 °C, and a gas pressure sensitivity of −2.27 nm MPa−1 in the gas pressure range of 0–0.3 MPa. MI has a temperature sensitivity of 0.05 nm °C−1 in the temperature range of 40 °C–80 °C, and a gas pressure sensitivity of zero in the gas pressure range of 0–0.3 MPa. Using the temperature and gas pressure sensitivities of FPI and MI to construct a measurement matrix, it is possible to simultaneously measure temperature and gas pressure, eliminating their cross-sensitivity. This sensor has the comprehensive advantages of compact structure, small size, easy manufacturing, low cost, high reliability, and high sensitivity, and is expected to be applied in industrial practice.

High-Sensitivity Seawater Salinity Sensing With Cladding Etched Fiber Bragg Grating Technology

Seawater salinity is an essential parameter to show the basic hydrological information of the ocean. Cladding etched fiber Bragg grating (CE-FBG) technology has potential in seawater salinity sensing because of its high sensitivity to surrounding refractive index. Here, we fabricated the different CE-FBG salinity sensing elements by using hydrofluoric (HF) acid based wet chemical etching. We encapsulated a CE-FBG and a bare FBG (B-FBG) into a salinity sensor to realize simultaneous measurement of seawater salinity and temperature. Various sensing characteristics of the CE-FBG, including salinity and temperature sensitivity, response time, hysteresis, repeatability, and long-term stability were investigated systematically. The salinity and temperature measurements of the CE-FBG sensor were highly consistent with those of the electronic salinometer, which indicates that fiber optic salinity sensor provides a new means for salinity measurement. Together, our results demonstrate the great potential of the CE-FBG salinity sensor for high sensitivity, long-term, and quasi-distributed seawater salinity monitoring.

Simultaneous 3D tracking and temperature measurements of L-PBF spatter particles using a single camera

Simultaneous 3D tracking and temperature measurements of L-PBF spatter particles using a single camera

Compact Vernier sensor with an all-fiber reflective scheme for simultaneous measurements of temperature and strain.

We propose an all-fiber reflective sensing scheme to simultaneously measure temperature and strain. A length of polarization-maintaining fiber serves as the sensing element, and a piece of hollow-core fiber assists with introducing Vernier effect. Both theoretical deductions and simulative studies have demonstrated the feasibility of the proposed Vernier sensor. Experimental results have shown that the sensor can deliver sensitivities of -88.73 nm/°C and 1.61 nm/με for temperature and strain, respectively. Further, Both theoretical analyses and experimental results have suggested the capability of simultaneous measurement for such a sensor. Significantly, the proposed Vernier sensor not only presents high sensitivities, but also exhibits a simple structure, compact size and light weight, as well as demonstrates ease of fabrication and hence high repeatability, thus holding great promise for widespread applications in daily life and industry world.

Twin background subtraction technique: A novel infrared technique for simultaneous thickness and temperature measurements of micro films

The study proposes a novel non-intrusive infrared technique to measure simultaneously the thickness and temperature of a thin layer that is semi-transparent to infrared radiation. The measurement method has been called Twin Background Subtraction technique. The technique simultaneously exploits the mid-wave IR emission from the film to be measured and the radiation attenuation by the same film of the emission coming from two backgrounds at different constant temperatures. This study discusses the method theoretically and experimentally, focusing on the uncertainties and the dependence on different parameters of the set-up and fluid physical properties.The fluid adopted for the film is water, and various tests have been carried out by changing its temperature between 15 and 50 °C and its thickness from 0 to 500 µm. The TBS technique was proven to be of interest for studying micro to mini films both from a qualitative and quantitative point of view for water films ranging between 10 µm and 350 µm.

Broadband ultrafast-laser-absorption spectroscopy for multi-hydrocarbon measurements near 3.3 µm in flames.

This paper presents the development and application of a broadband ultrafast-laser-absorption-spectroscopy (ULAS) technique operating in the mid-infrared for simultaneous measurements of temperature, methane (C H 4), and propane (C 3 H 8) mole fractions. Single-shot measurements targeting the C-H stretch fundamental vibration bands of C H 4 and C 3 H 8 near 3.3µm were acquired in both a heated gas cell up to ≈650K and laminar diffusion flames at 5kHz. The average temperature error is 0.6%. The average species mole fraction errors are 5.4% for C H 4 and 9.9% for C 3 H 8. This demonstrates that ULAS is capable of providing high-fidelity hydrocarbon-based thermometry and simultaneous measurements of both large and small hydrocarbons in combustion gases.

Dual-Parameter Sensor for Temperature and Strain Measurement Based on Antiresonance Effect and Few-Mode Fiber

A simple and novel hybrid interferometer based on the antiresonance (AR) effect and Mach–Zehnder interference (MZI), which enables simultaneous measurement of temperature and strain, is proposed and investigated. The sensor is made by cascading a 30 cm section of a few-mode fiber (FMF) and a 3.376 mm hollow-core fiber (HCF) through a single-mode fiber (SMF). The FMF and SMF are fused without misalignment to excite two stable modes, thereby forming a Mach–Zehnder interferometer. Concurrently, the introduction of HCF can effectively excite the AR effect, which is manifested in the transmission spectrum as two different dips at the same time caused by the difference in the two physical mechanisms, showing diverse responses to both external temperature and strain. This difference can be used to construct a cross-coefficient matrix to implement the simultaneous measurement of temperature and strain. The experimental results demonstrate that the AR effect and MZI correspond to strain sensitivities of –0.87 and –2.29 pm/µε, respectively, and temperature sensitivities of 15.68 and –13.93 pm/°C, respectively. Furthermore, the sensor is also tested for repeatability, and the results show that it has good repeatability and great potential in sensing applications.