Calibration Unit Research Articles

Distributed vibration and temperature sensing system by multiplexed fiber scattering spectra

A new, to the best of our knowledge, distributed optical fiber vibration and temperature hybrid sensing system is proposed and experimentally demonstrated. The proposed system only employs two signal channels, which is more compact and practical. Based on the structure of the optical time domain reflectometer (OTDR), the Rayleigh scattering light and the Raman anti-Stokes scattering light is extracted for vibration and temperature sensing, respectively. For vibration sensing, a new differential location algorithm based on polarization state analysis of the Rayleigh scattering light is proposed to locate the vibration events. It first rectifies the original OTDR traces by fiber attenuation compensation to make each position in it with the same pulse power level. And then, by difference of adjacent traces and threshold discrimination, the vibration positions are identified and located. For temperature sensing, a temperature calibration unit and algorithm are adopted to dynamically correct the trace data and reduce the temperature measurement error caused by the instability of the pulse laser source. The experiment is conducted with a fiber range of about 12 km and laser pulse width of 60 ns, and the experimental results show that the maximum error range for temperature measurement is −0.7∘C to 1.3°C, with a root mean square (RMS) error of 0.85°C in the entire temperature measurement range. Additionally, the spatial resolution (SR) for both vibration and temperature sensing is 6 m.

Combination of real-time and hyphenated mass spectrometry for improved characterisation of exhaled breath biomarkers in clinical research.

Exhaled breath volatilomics is a powerful non-invasive tool for biomarker discovery in medical applications, but compound annotation is essential for pathophysiological insights and technology transfer. This study was aimed at investigating the interest of a hybrid approach combining real-time proton transfer reaction-time-of-flight mass spectrometry (PTR-TOF-MS) with comprehensive thermal desorption-two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (TD-GCxGC-TOF-MS) to enhance the analysis and characterization of VOCs in clinical research, using COVID-19 as a use case. VOC biomarker candidates were selected from clinical research using PTR-TOF-MS fingerprinting in patients with COVID-19 and matched to the Human Breathomic Database. Corresponding analytical standards were analysed using both a liquid calibration unit coupled to PTR-TOF-MS and TD-GCxGC-TOF-MS, together with confirmation on new clinical samples with TD-GCxGC-TOF-MS. From 26 potential VOC biomarkers, 23 were successfully detected with PTR-TOF-MS. All VOCs were successfully detected using TD-GCxGC-TOF-MS, providing effective separation of highly chemically related compounds, including isomers, and enabling high-confidence annotation based on two-dimensional chromatographic separation and mass spectra. Four VOCs were identified with a level 1 annotation in the clinical samples. For future applications, the combination of real-time PTR-TOF-MS and comprehensive TD-GCxGC-TOF-MS, at least on a subset of samples from a whole study, would enhance the performance of VOC annotation, offering potential advancements in biomarker discovery for clinical research.

Optimization design and evaluation of composited fiber optic sensors for monitoring ammonia gas with relative error calibration unit

In this paper, a relative error calibration unit has been designed to analyze and calibrate the common relative errors in optical fiber gas detection system based on directly absorption spectrum (DAS) technology. The ammonia gas was successfully encapsulated in one cut of hollow core fiber as the closed micro-cavity reference cell by dipping saturated solution and cascade-fusing fibers. Through the difference algorithm, the maximum relative error caused by the power fluctuation of the light source is reduced by 85.3 %; to reduce the temperature drift effect caused by optical fiber structure and ammonia absorbance, the calibration equation is obtained by fitting and inversion calculation. The temperature relative error decreases by 95 %. The proposed self-referencing hollow fiber gas sensing probe has a compact structure and can be used for precise monitoring of harmful gases in harsh environments such as narrow space, strong electromagnetic interference, high temperature and humidity.

Analysis of Iron (Fe) Content in Breast Milk of Breastfeeding Mothers with Level Anemia Normal, Mild and Moderate

Aims: The study aimed to determine the level of iron (Fe) in breast milk samples from breastfeeding mothers who were not anemic (normal), had mild anemia, and had moderate anemia. Methodology: This research is descriptive in nature with a cross-sectional research design. The research subjects were 30 breast milk samples from breastfeeding mothers who had babies aged 0-6 months in TTU Regency, East Nusa Tenggara. 10 samples each in the categories of no anemia (normal), mild anemia, and moderate anemia. Analysis of Fe levels in breast milk samples using Atomic Absorption Spectroscopy (SSA) at the Testing, Calibration, and Certification Services Laboratory Unit, Bogor Agricultural Institute. Results: The results of the analysis showed that the average Fe content in breast milk samples from breastfeeding mothers (normal category) was 4.17 mg/L; Fe levels in breast milk samples from breastfeeding mothers (mild anemia category) were 2.01 mg/L; while the Fe level in breast milk samples from breastfeeding mothers (moderate anemia category) was 1.05 mg/L. From the average figures, it can be seen that there is no significant difference in Fe levels between the three breast milk samples, which is confirmed by the distribution of Fe levels for the 30 samples which is not much different, even from the minimum number of Fe levels in breast milk samples from breastfeeding mothers (normal). still found at 1.03 mg/L (almost the same as the minimum Fe level for breast milk samples from breastfeeding mothers (mild anemia), namely 0.70 mg/L. Conclusion: there were no significant differences in Fe levels in breast milk samples from breastfeeding mothers in the categories of no anemia (normal), mild anemia, and moderate anemia. However, it is still recommended that it is very important to ensure sufficient iron in breast milk to help the baby's growth and development.

Heimdallr, Baldr, and Solarstein: designing the next generation of VLTI instruments in the Asgard suite

High angular resolution imaging is an increasingly important capability in contemporary astrophysics. Of particular relevance to emerging fields such as the characterization of exoplanetary systems, imaging at the required spatial scales and contrast levels results in forbidding challenges in the correction of atmospheric phase errors, which in turn drives demanding requirements for precise wavefront sensing. Asgard is the next-generation instrument suite at the European Southern Observatory’s Very Large Telescope Interferometer (VLTI), targeting advances in sensitivity, spectral resolution, and nulling interferometry. In this paper, we describe the requirements and designs of three core modules: Heimdallr, a beam combiner for fringe tracking, low order wavefront correction, and visibility science; Baldr, a Zernike wavefront sensor to correct high order atmospheric aberrations; and Solarstein, an alignment and calibration unit. In addition, we draw generalizable insights for designing such system and discuss integration plans.

Experimental Investigation on the Transfer Behavior and Environmental Influences of Low-Noise Integrated Electronic Piezoelectric Acceleration Sensors

Acceleration sensors are vital for assessing engineering structures by measuring properties like natural frequencies. In practice, engineering structures often have low natural frequencies and face harsh environmental conditions. Understanding sensor behavior on such structures is crucial for reliable measurements. The research focus is on understanding the behavior of acceleration sensors in harsh environmental conditions within the low-frequency acceleration range. The main question is how to distinguish sensor behavior from structural influences to minimize errors in assessing engineering structure conditions. To investigate this, the sensors are tested using a long-stroke calibration unit under varying temperature and humidity conditions. Additionally, a mini-monitoring system configured with four IEPE sensors is applied to a small-scale support structure within a climate chamber. For the evaluation, a signal-energy approach is employed to distinguish sensor behavior from structural behavior. The findings show that IEPE sensors display temperature-dependent nonlinear transmission behavior within the low-frequency acceleration range, with humidity having negligible impact. To ensure accurate engineering structure assessment, it is crucial to separate sensor behavior from structural influences using signal energy in the time domain. This study underscores the need to compensate for systematic effects, preventing the underestimation of vibration energy at low temperatures and overestimation at higher temperatures when using IEPE sensors for engineering structure monitoring.

Bayesian calibration of quasi-static field distortions in HARMONI

ABSTRACT The high angular resolution monolithic optical and near-infrared Integral field spectrograph is the first light visible and near-infrared integral field spectrograph for the Extremely Large Telescope. To reach the diffraction limit of the telescope (≈ 10 mas) and maintain an optimal image quality over long exposures, an accurate measurement of geometrical distortions in the instrument’s guide star field is needed. Geometrical distortions affecting the guide stars map directly to pointing errors of the science field. The systematic contribution to the pointing error can be calibrated and removed by a corrective model. In this work, we propose a formulation of the corrective model that aims to calibrate the geometrical field distortions down to a given target residual, as well as reducing the time spent in calibrations. We also propose a calibration procedure that accounts for the uncertainties of the measurement process. We developed a tool named harmoni-pm to simulate the expected pointing error caused by geometrical distortions and validate the effectiveness of the proposed corrective model. We also relied on pseudo Zernike polynomials to formulate the model, and the Bayesian theoretical framework to study the propagation of uncertainties along the calibration process. Compared with the classical calibration algorithm, the Bayesian calibration algorithm was able to reduce the number of calibration points required to reach the same model residual. Additionally, we were able to optimize the hardware of the Geometrical Calibration Unit and reduce the time required to achieve the calibration goal.

Deep click interest network for reranking hotels

Nowadays, e-commerce platforms of hotels have become a new trend to help people book hotels online. Interest modeling aims to automatically construct user interests that are critical for e-commerce platforms. Although interest modeling has achieved noticeable successes in product recommendations, it has not been explored in hotel search, especially in the reranking stage. This paper studies the interest modeling task for reranking hotels, and identifies two key challenges—high behavior sparsity and large interest gap. To address the challenges, we propose the deep click interest network (DCIN). High behavior sparsity keeps us from extracting rich semantics to characterize user interest preference. Accordingly, we propose the deep click concept to model the multi-view semantics of a click and then enrich the semantics of both a single click and a click sequence, so that the difficulty caused by the behavior sparsity can be addressed. To address the interest gap challenge, DCIN models user interests with two cascaded units: (i) Mutual-attention Interest Calibration Unit (ICU), which uses the candidate hotel to calibrate the embedding of every click, since the candidate hotel is selected by the ranking stage and can represent user current interests to some extent. So the gap between the calibrated embedding and user current interests can be diminished; (ii) Multi-attention Interest Aggregation Unit (IAU), which estimates the weight of a calibrated embedding from multiple perspectives, i.e., context, user feedback and interest consistency. So the calibrated embeddings, which are relevant to the current query context and important to the user, dominate user current interests, and thus the interest gap can be further diminished. Offline experiments over two large datasets and online A/B testing over the platform of Meituan-Hotel show that DCIN significantly outperforms the baselines and improved baselines. Notably, DCIN has been deployed in Meituan-Hotel, resulting in an increase of 2.40% in Click Through Conversion Rate (CTCVR) and that of 1.09% in Click Through Rate (CTR).

Analysis of Error Sources of a Torque and Rotation Angle Calibration Unit Based on Statics

The structure and working principle of the torque calibration unit, the index angle calibration unit, and the loading mechanism are introduced. Using finite element analysis tools for static analysis, the error sources of the calibration process are obtained and the influence on the calibration results is analyzed. Among them, the influence of connecting rod deformation, torque transmission characteristics, and flexible deformation on the calibration accuracy is small and can be ignored. Bearing friction, coaxiality, and micro-deformation of the test bench are inherent errors of the system. For its own inherent error attribute, it will not affect the relationship between the sensor to be calibrated and the standard sensor on the output shaft of the index test bench, that is, it will not affect the calibration process of the sensor to be calibrated later.

A 40-50 GHz RF Front-End with Integrated Local Oscillator Leakage Calibration.

This article presents a transmitter (TX) front-end operating at frequencies covering 40-50 GHz, including a differential quadrature mixer with integrated amplitude and phase imbalance tuning, a power amplifier, and a detection mixer (DM) that supports local oscillator (LO) leakage signal or image signal calibration. Benefiting from the amplitude and phase imbalance tuning network of the in-phase quadrature (IQ) signal generator at the LO input, the TX exhibits more than 30 dBc image signal rejection over the full frequency band without any post-calibration. Based on the LO leakage signal fed back by the DM integrated at the RF output, the LO leakage of the TX has been improved by more than 10 dB through the LO leakage calibration module integrated in the quadrature mixer. When the intermediate frequency (IF) signal is fixed at 1 GHz, the TX's 1 dB compressed output power (OP1 dB) is higher than 13.5 dBm over the operating band. Thanks to the LO leakage signal calibration unit and the IQ signal generator, the TX is compliant with the error vector magnitude (EVM) requirement of the IEEE 802.11aj standard up to the 64-quadrature amplitude modulation (QAM) operating mode.

Learnable Distribution Calibration for Few-Shot Class-Incremental Learning.

Few-shot class-incremental learning (FSCIL) faces the challenges of memorizing old class distributions and estimating new class distributions given few training samples. In this study, we propose a learnable distribution calibration (LDC) approach, to systematically solve these two challenges using a unified framework. LDC is built upon a parameterized calibration unit (PCU), which initializes biased distributions for all classes based on classifier vectors (memory-free) and a single covariance matrix. The covariance matrix is shared by all classes, so that the memory costs are fixed. During base training, PCU is endowed with the ability to calibrate biased distributions by recurrently updating sampled features under supervision of real distributions. During incremental learning, PCU recovers distributions for old classes to avoid 'forgetting', as well as estimating distributions and augmenting samples for new classes to alleviate 'over-fitting' caused by the biased distributions of few-shot samples. LDC is theoretically plausible by formatting a variational inference procedure. It improves FSCIL's flexibility as the training procedure requires no class similarity priori. Experiments on CUB200, CIFAR100, and mini-ImageNet datasets show that LDC respectively outperforms the state-of-the-arts by 4.64%, 1.98%, and 3.97%. LDC's effectiveness is also validated on few-shot learning scenarios.

Influence of the variable geometry of the flow switch nozzle exit on the metrological characteristics of a calibration unit with weighing devices

Influence of the variable geometry of the flow switch nozzle exit on the metrological characteristics of a calibration unit with weighing devices

Modeling and optimization of synergistic ozone-ultraviolet-chlorine process for reclaimed water disinfection: From laboratory tests to software simulation.

The ozone-ultraviolet (UV)-chlorine process is a highly effective method of disinfection in water reuse system, but currently still lacks precise quantification and accurate control. It is difficult to determine the dosage of each disinfectant because of the complex interactions that occur between disinfection units and the complicated mathematical calculation required. In this study, we proposed a dosage optimization model for ozone-UV-chlorine synergistic disinfection process. The model was able to identify the cost-effective doses of the disinfectants under the constraints of microbial inactivation, decolorization, and residual chlorine retention requirements. Specifically, the simulation of microbial inactivation rates during synergistic disinfection process was accomplished through quantification of the synergistic effects between disinfection units and the introduction of enhancement coefficients. In order to solve this optimization model rapidly and automatically, a MATLAB-based software program with graphical user interface was developed. This software consisted of calibration unit, prediction unit, assessment unit, and optimization unit, and was able to simulate synergistic ozone-UV-chlorine process and identify the optimal dose of ozone, UV, and chlorine. Validation experiments revealed good agreements between the experimental data and the results calculated by the developed software. The developed software is believed to help the water reclamation plants improve disinfection efficiency and reduce the operational costs of synergistic disinfection processes.

Inf uence of the variable geometry of the diverter nozzle on the metrological characteristics of a calibration unit with weighing devices

This article discusses the issues of improving the metrological characteristics, weight-dimensional and technical and economic indicators of calibration installations with weighing devices due to the introduction of a fl ow switch with a variable nozzle exit geometry into their design. It is assumed that the use of this design of the fl ow switch will solve the problem of fi lling the nozzle exit with water, reduce the dimensions of the hydraulic path, simplify the maintenance procedure, and reduce the cost of installations. A description of the design, principles of operation and a timing diagram of a fl ow switch with a variable nozzle exit geometry are presented. The local hydrodynamic characteristics of the water fl ow by a Pitot tube in the nozzle exit are studied with a change in its width in the mass fl ow rate range from 25 to 550 t/h. The optimal values of the nozzle cut width are experimentally determined depending on the value of the mass fl ow rate of the liquid, at which it is completely fi lled with liquid. A study of the metrological characteristics of a calibration installation with weighing devices, which includes a fl ow switch with a variable nozzle exit geometry, methods of indirect measurements and comparisons using a comparison standard in a wide range of liquid mass fl ow rates, has been carried out. The impact on the metrological characteristics of a calibration installation with weighing devices of the nozzle cut width in the investigated range of liquid fl ow is established. Graphical dependences of the expanded measurement uncertainty of the installation when reproducing the unit of liquid mass fl ow rate on the measurement time interval and on the mass fl ow rate of the liquid are presented. Based on the research results, the optimal values of the nozzle cut width and measurement time intervals were determined depending on the mass fl ow rates of the liquid when using a fl ow switch with a variable nozzle cut geometry. The expansion of the range of operation of weighing devices, which are part of the verifi cation installations with weighing devices, is justifi ed. According to the results of the research, the proposed design of the fl ow switch with a variable geometry of the nozzle exit is recommended for use in the design of new and modernization of installations for calibration with weight devices of fl ow switches.

Development of a flat calibration unit for accurate flat fielding in the mid-infrared region

Development of a flat calibration unit for accurate flat fielding in the mid-infrared region

Solar Light Radiometry Calibration Unit for a ScanPol Polarimeter of the Aerosol-UA Space Mission

The Aerosol-UA space mission will study aerosol microphysical characteristics in the Earth’s atmosphere based on the multispectral scanning polarimeter (ScanPol) and imaging polarimeter (MSIP). Both polarimeters must be precisely calibrated on the ground and in orbit to provide correct measurements. This paper considers the results of developing an experimental device for the radiometric calibration of the ScanPol. We consider the calibration unit design and operation principle to form a luminous flux with unchanged or well-predicted characteristics in a specified direction. The construction of the radiometric calibration unit is based on a sun-illuminated reflective diffuser made from the white opal glass MS20. We evaluated the scattering and polarization characteristics of the diffuser in laboratory experiments at a wide range of wavelengths. The results suggest that the polarization properties of the diffuser are negligible. The diffuser scattering parameters are close to Lambertian for illuminance conditions, which is necessary for radiometric calibration. The calibration unit was manufactured and tested during field observations of solar radiation. The results will be used for its improvement, mainly to reduce the observed stray scattered radiation entering the telescopes of the ScanPol polarization state analyzer.

A novel photochemical conversion technique for reliable calibration of peroxyacetyl nitrate (PAN) analyzers

Photochemical synthesis of peroxyacetyl nitrate (PAN) through irradiating air mixtures of NO and acetone is prevailingly adopted for calibrating PAN analyzers, but few users of PAN analyzers provide evidence to certify the calibration reliability. Here we report a nonnegligible variation (up to ~50 %) of PAN synthesized in the calibration unit of a commercial PAN analyzer, whereas PAN synthesized in the two custom-made reactors could achieve stable values with variations of <2.5 %. Compared with a straight quartz tube flow reactor (SQTFR), PAN synthesized by a coiled quartz tube flow reactor (CQTFR) could achieve more stable (relative standard deviation: <0.66 % versus 2.49 %) and larger (PANCQTFR/PANSQTFR: 1.04–1.10) values. The residence time and reaction temperature of photochemical mixtures in CQTFR were found to be the key factors affecting PAN synthesis, with their optimal values of 30–60 s and 30–35 °C for achieving the highest PAN levels. The photochemical conversion efficiencies of NO to PAN in CQTFR under the optimal conditions were successfully measured to be 98.5 ± 0.5 % based on the alkaline-absorption method. Therefore, CQTFR is suggested to be adopted for calibrating PAN analyzers to reduce calibration uncertainties.

Transition of Standard Dosimetry of Absorbed Dose to Water in External Beam Radiotherapy [Part 1]

The radiotherapy is performed with the aim of delivering the optimal dose to the target volume with minimal side effect of surrounding normal tissue. For this purpose, quality assurance is essential to ensure that the target volume is correctly irradiated in the optimal geometrical arrangement, and the absorbed dose evaluation is essential to ensure that the prescribed dose is correctly delivered. The absorbed doses are generally evaluated using a small cavity ionization chamber that utilizes gas ionization. For the evaluation of absorbed dose to water using ionization chambers, the national dose and charge standards, ionization chambers and electrometer calibration systems are required. And it is also required standard dosimetry protocol that recommend conditions such as fields, depths, and optimal ionization chambers for the measurement, as well as reliable physical data. This manuscript reviews the transition of standard dosimetry of absorbed dose to water in external beam radiotherapy, including the background of dose standards, ionization chamber calibration systems, units, and physical constants.

Experimental Research on Unit Operation for Fruit Crops’ Bones Calibration

The article presents the results of the implementation of the mathematical planning of the experiment to determine the optimal parameters of the calibration process of cherry, sweet cherry, cherry plum, apricot and almond seeds. The essence of this process is the separation of seeds (bones) of fruit crops into fractions homogenous in size in order to highlight the middle fraction, which is about 80% of the total number of bones. The bones of the middle fraction are of the highest quality and are most suitable for sowing. The shape of the bones was evaluated by three parameters: length, width, and height. Calibration was performed according to the width of the bone. To carry out experimental studies, a calibration device was developed, the working body of which is the sieve part. Ball cleaners were used to prevent clogging of the perforated sieve. A mathematical theory of experimental planning was used. The criterion of optimization for all fruit crops was taken as an indicator of the quality of bone division into homogeneous fractions. The functional dependence of this indicator on the frequency and amplitude of oscillations of the grating part of the calibration unit, as well as on the angle of inclination of the sieves, was investigated. To implement the experimental data, we used a rotatable Boks plan of the second order. Regression models of the cherry, sweet cherry, cherry plum, apricot, and almond calibration process were obtained. Adequacy of the models was assessed by Fisher’s criterion. As a result, the optimal operating parameters of the installation were determined. This ensures the qualitative separation of the bones of fruit crops into homogeneous fractions with a mass deviation of up to 7%. An assessment of the quality of work of ball sieve cleaners was carried out. To do this, we used the coefficient of efficiency of the live cross-section. With the optimal parameters of the installation, the value of this coefficient of the unit for all fruit crops is within 0.87 to 0.95. This indicates that the calibration process is of high quality.

Calibration strategy of the JUNO-TAO experiment

The Taishan Antineutrino Observatory (TAO or JUNO-TAO) is a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). Located near a reactor of the Taishan Nuclear Power Plant, TAO will measure the reactor antineutrino energy spectrum with an unprecedented energy resolution of <2% at 1 MeV. Energy calibration is critical to achieve such a high energy resolution. Using the Automated Calibration Unit (ACU) and the Cable Loop System (CLS), multiple radioactive sources are deployed to various positions in the TAO detector for energy calibration. The residual non-uniformity can be controlled within 0.2%. The energy resolution degradation and energy bias caused by the residual non-uniformity can be controlled within 0.05% and 0.3%, respectively. The uncertainty of the non-linear energy response can be controlled within 0.6% with the radioactive sources of various energies, and could be further improved with cosmogenic ^{12}{textrm{B}} which is produced by the interaction of cosmic muon in the liquid scintillator. The stability of other detector parameters, e.g., the gain of each Silicon Photo-multiplier, will be monitored with an ultraviolet LED calibration system.