Instrument Calibration Research Articles

Calibration of MAJIS (Moons And Jupiter Imaging Spectrometer). I. On-ground setup description and characterization.

The visible and infrared Moon And Jupiter Imaging Spectrometer (MAJIS), aboard the JUpiter ICy Moons Explorer (JUICE) spacecraft, will characterize the composition of the surfaces and atmospheres of the Jupiter system. Prior to the launch, a campaign was carried out to obtain the measurements needed to calibrate the instrument. The aim was not only to produce data for the calculation of the radiometric, spectral, and spatial transfer functions but also to evaluate MAJIS performance, such as signal-to-noise ratio and amount of straylight, under near-flight conditions. Here, we first describe the setup implemented to obtain these measurements, based on five optical channels. We notably emphasize the concepts used to mitigate thermal infrared emissions generated at ambient temperatures, since the MAJIS spectral range extends up to 5.6 µm. Then, we characterize the performance of the setup by detailing the validation measurements obtained before the campaign. In particular, the radiometric, geometric, and spectral properties of the setup needed for the inversion of collected data and the calculation of the instrument's calibration functions are presented and discussed. Finally, we provide an overview of conducted measurements with MAJIS, and we discuss unforeseen events encountered during the on-ground calibration campaign.

Factors influencing the dissolution rate of radon gas in water

Measurements of radon (222Rn) in water are widely utilized across various disciplines, including technology, medicine, exploration, and ecological preservation. For accurate radon measurements in water, the availability of a standardized radon solution is essential. Researchers have predominantly concentrated on the radon concentration in water (RCW) once radon distribution equilibrium is achieved, rather than the rate of radon dissolution prior to equilibrium, in the development of standard radon solutions. This makes the preparation speed of the calibration standards radon solution slow, which seriously restricts the research and development of the standard device. The purpose of this paper is to investigate the correlation between the rate of radon dissolution and both the concentration of gaseous radon and the stirring speed. Four conclusions have been derived through univariate analysis. ➀ The radon concentration in water (RCW) increases with the duration of radon dissolution, eventually reaching a state of equilibrium. ➁ The increase in gas radon concentration correlates with a simultaneous rise in the rate of radon dissolution, while the time required for radon distribution equilibrium remains constant. ➂ The augmentation of the stirring speed enhances the rate of radon dissolution, Concurrently reducing the time needed for RCW to reach equilibrium.➃ When the stirring speed is excessively high, it results in substantial fluctuations in both RCW and the rate of radon dissolution. Consequently, when employing this method for the preparation of radon solutions, it is advisable to regulate the duration of radon dissolution to 30 min at a rate of 380 rad/min and 10 min at a rate of 480 rad/min. This regulation ensures the attainment of precise concentrations. Under conditions of environmental stability, manipulation of gas radon concentration alone proves sufficient for adjusting RCW . These empirical findings furnish a robust foundation for the efficient preparation of standardized radon solutions and the requisite apparatus, essential for the calibration and accuracy of radon measurement instruments.

WEATHERING THE STORM: A SYSTEMATIC LITERATURE REVIEW OF WEATHER STATIONS’ OBSERVATIONAL PRACTICES

This literature review examines the accuracy, error frequency, and the impact of workload and decision-making on the weather observations made by PAGASA synoptic station personnel in the Cordillera Administrative Region (CAR). The accuracy of weather data collected by PAGASA is critical for reliable forecasting and timely decision-making in various sectors, including agriculture, disaster management, and transportation. The review highlights key factors influencing data accuracy, such as instrument calibration and human error. Studies show that while the accuracy of weather observations is generally high, occasional discrepancies occur, often due to technical issues or human mistakes in data recording, especially during extreme weather events. The review also explores the frequency of errors in weather observation data. Research indicates that errors are infrequent, but they are more likely to occur during severe weather conditions or in cases of equipment malfunctions or power failures. Although external factors can occasionally disrupt the data collection process, the overall frequency of errors remains relatively low. Furthermore, the impact of workload and decision-making on the accuracy of observations is discussed. Heavy workloads during peak weather seasons and the pressure of rapid decision-making during extreme weather events were found to contribute to an increased likelihood of errors. Studies emphasize the importance of managing workload and decision-making stress to maintain the quality of data. The review concludes by suggesting that further research, training, and technological improvements are needed to enhance the accuracy and reliability of weather observations in PAGASA synoptic stations in CAR.

Improving relative humidity measurements on Mars: new laboratory calibration measurements

Abstract. In this paper we present new calibration measurements that have been performed with the ground reference models of the relative humidity instruments of the Mars Science Laboratory (MSL), Mars 2020 and ExoMars missions. All instruments are based on capacitive sensor head technology, and they are developed, manufactured and tested by the Finnish Meteorological Institute (FMI). Calibration of capacitive humidity sensors for the Martian environment has been a challenging task and special facilities are needed in order to create Martian conditions including all relevant environmental parameters that can be accurately controlled and measured: low pressure, low temperature, carbon dioxide environment and especially humidity. A measurement campaign was performed at the German Aerospace Center (DLR) PASLAB (Planetary Analog Simulation Laboratory) to determine relative humidity calibration datasets for REMS-H, MEDA HS and METEO-H instruments in temperatures from −30 °C down to −70 °C in low-pressure CO2. In addition to the stable point humidity calibration measurements in CO2, the instrument performance was tested with the actual Martian atmosphere composition and during long continuous measurements. The new calibration dataset has already been used in the flight calibration of the MEDA HS instrument, resulting in successful calibration and excellent accuracy. The results from this campaign will further improve relative humidity measurements on Mars by providing the means to reanalyze the current calibration of the REMS-H flight model and by allowing more accurate comparison between the two instruments currently on the Martian surface.

Optimizing radiation dosimetry: Impact of PMMA layers on electronic equilibrium for the calibration of radiation protection instruments

In radiation dosimetry, achieving electronic equilibrium is vital for accurate dose measurements in radioprotection. This study investigates the effect of Poly Methyl Methacrylate (PMMA) layers, known by its chemical formula C5H8O2 and a density of 1.19 g/cm³ (PNNL, 2011), on electronic equilibrium for the calibration of radiation protection instruments, focusing on photon beams of varying energies. Using DOSIMEX 2.0 simulation software, we modeled the influence of PMMA thickness on calibration factors across different X-ray and gamma-ray beam energies. Experimental validation with Cs-137 and Co-60 sources confirmed the reliability of the simulation. Our results highlight that while PMMA layers have a minimal impact on calibration for higher-energy beams, their role becomes significant for energies below 40 keV. For X-ray beams (From 30 to 140 kV), the results show minimal calibration factor deviation (<1.6%), whereas radionuclide beams exhibit more significant variations (4.1%), necessitating customized calibration approaches. This study underscores the importance of adhering to ISO 4037-3 standards in radioprotection, particularly in low-energy scenarios, to ensure the precision of calibration procedures and optimize radiation protection practices. Furthermore, based on the results obtained, the absence of PMMA does not have a dramatic effect on the calibration of X-ray radiation instruments, whereas for gamma-ray beams, it has a significant impact.

International intercomparison of Radon 222 activity concentration calibration facilities

The Coalition of International Radon Associations (COIRA) organised an inter-comparison of Rn-222 (radon) activity concentrations reported by calibration laboratories. A set of three AlphaGUARDs were used as transfer reference instruments against which to compare reported Rn-222 activity concentrations. Rn-222 activity concentration calibration facilities (sometimes termed chambers) from seven countries (Australia, US, Czech Republic, Spain, England, Sweden, Canada), and three continents participated in this project. The objective of the study was to provide information useful to calibration chamber operators and public health officials in the improvement of measurement and control systems, the maintenance of performance standards for measurements, and regulatory requirements for calibrations. This work builds upon and expands previous interlaboratory comparisons and provides data for estimating and using calibration uncertainty values as part of overall field error estimates and limits. A simple proportional difference between laboratories is presented here, calculated as the average for N hours of each hour’s difference between the laboratory’s concentration and the average of the three reference instruments. This percent difference ranged from less than 0.5% to just less than 8%. This work demonstrates that the ANSI/AARST standards limit of 8% for the estimated unexpanded (one sigma) individual calibration estimated uncertainty for continuous radon monitor calibration facilities in the US is achievable. However, given the few standards regarding calibration of Rn-222 activity concentration measurement instruments that themselves are often used to calibrate secondary and tertiary Rn-222 calibration facilities, there is a great need for continued interlaboratory comparisons to harmonise and document the calibration of Rn-222 activity concentrations.

A Mystery of the Inconsistency Between Microwave Polarimetric Observations and Radiative Transfer Simulations

AbstractA factor of 2 difference is found between microwave brightness temperature (TB) observations and simulations from vector radiative transfer models. A physical explanation of this difference is related to the calibration process. In principle, for the calibration of polarimetric instruments of a total power radiometer, the radiation should be only half of the values derived from Planck function but in the actual calibration process, a full value is used. When this full value is converted to a TB it is approximately, but not exactly, twice the TB simulated by a vector radiative transfer model. This inconsistency is verified by simulations of three conically scanning microwave imagers (WindSat, AMSR2 and MWRI) and one cross‐track scanning microwave sounder (AMSU‐A). This difference cannot be compensated simply by dividing a factor of 2 to the processed TBs, especially at high frequencies or at low physical temperatures due to the nonlinear property of Planck function.

Magnetoelastic Immunosensor for the Rapid Detection of SARS-CoV-2 in Bioaerosols.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a protein-coated, single-stranded RNA virus that parasitizes and infects primates, including humans. The current detection methods are mainly carried out using humans as a medium, such as a chest computed tomography (CT) examination, nucleic acid detection, antibody detection, and antigen detection. In addition, SARS-CoV-2 in bioaerosols is an important way of transmission and infection, which has attracted wide attention. In this paper, we simulate a sampling system of SARS-CoV-2 in bioaerosols and detect SARS-CoV-2 in bioaerosols by means of a magnetoelastic (ME) sensing device based on an Android intelligent terminal, which can directly detect SARS-CoV-2 in bioaerosols in a certain unit environment. This approach aims to achieve early detection and prevention. The experimental results show that the sampling system can successfully collect SARS-CoV-2 in bioaerosols. In the linear range of 5-20 ng/mL, the ME sensing detection system results closely match those of the calibration instrument (VNA), with goodness-of-fit values of 0.997 and 0.995, respectively. This work demonstrates that the ME sensing detection system proposed is stable, highly specific, real-time, rapid, and has certain reference values and feasibility.

Policy Gaps and Diverging Perceptions of Effectiveness: An Assessment of Sustainable Permanent Grassland Management in Switzerland

This article focuses on the effectiveness of the Swiss policy mix promoting sustainable permanent grassland (PG) management in the country. We used the Cascade Framework and stakeholder’s sentiment analysis to qualitatively assess propagation pathways for generating policy effectiveness in terms of PGs’ deliverance of ecosystem services (ESs), to ultimately enable sustainable PG management. We employed a mixed-method approach combining a review of governmental documents, formal policies and policy evaluations with semi-structured interviews with Swiss stakeholders. Through this analysis, we identified 16 policy instruments influencing PG management, including 3 regulatory instruments, 11 incentive instruments, and 2 informational instruments. Results showed that these instruments primarily aim to promote sustainable PG management by employing measures targeting the very structure and composition of the landscape. As such, we found gaps in the types of instruments employed, particularly in terms of demand-side policies, which can explain the poor policy outcomes in relation to a number of environmental quality objectives. In parallel, we found that most of the interviewed stakeholders considered Swiss grassland policy as generally effective, mainly because it was perceived as democratic. While this study focuses on Switzerland, its novel conceptual and methodological approach of using the cascade-framework for policy analysis can be applied to other biogeographical regions and socio-economic contexts. Our findings can improve the calibration of future policy instruments to enable land managers and grassland landscape users to restore or maintain PGs in good ecological condition, by targeting mechanisms that can ensure achieving environmental quality objectives while remaining democratically legitimate.

Stabilization of light sources with digital micromirror devices for calibration of high-precision photometric instruments

Stabilization of light sources with digital micromirror devices for calibration of high-precision photometric instruments

Predicción de lectura en instrumento patrón para una empresa de metrología a través de un dashboard empleando algoritmos de regresión

Nowadays, metrology has employed advanced techniques such as artificial intelligence, the internet of things and data analysis, all with the aim of accurately and precisely measuring different physical magnitudes. All this is known today as metrology 4.0, which has as its main objective to ensure the reliability and accuracy of measurements in fields such as industry. In this context, a web application is proposed for a company dedicated to the calibration of instruments, in which regression algorithms are applied for prediction in their calibration instruments. This will not only provide better quality and more reliable results to customers, but will also optimize the company's processes and improve the efficiency of decision making related to instrument calibration. It is expected that, through the use of regression algorithms, the company will predict when the standard instrument will give bad readings. This will make it possible to send the instrument for calibration in advance, avoiding errors and guaranteeing measurement accuracy. Although concrete results are not yet available, a significant improvement in the accuracy and reliability of predictions is anticipated, as well as in the company's operational efficiency.

The ExoMars 2028 WISDOM antenna assembly: Description and characterization

While ground penetrating radars have been extensively researched on Earth, the high-resolution exploration and imaging of the shallow subsurface of celestial bodies in our solar system is still in its early stages, with only a handful of systems capable of the task.Designing high-resolution radar systems can be a complex task due to the large frequency bandwidth required by the antennas to achieve high vertical resolution. The WISDOM GPR, as part of the 2028 ExoMars mission, is a highly capable and challenging instrument in this context, given its fully-polarimetric setup and mission constraints on the operating environment, robustness, as well as mass and size budget.This paper outlines the development and characterization process of the WISDOM antenna assembly, which can serve as a model for future radar systems. Furthermore, it presents the results of the antenna characterization as the foundation for instrument calibration and optimal radar sounding outcomes.

Analysis of silver metal with a Thermo Scientific K-Alpha XPS instrument at 50 and 200 eV pass energies

Silver metal was analyzed by x-ray photoelectron spectroscopy using a Thermo Scientific K-Alpha instrument with an Al Kα x-ray source (1486.6 eV). The silver survey spectrum and high-resolution Ag 3d, Ag M4N45N45, Ag M5N45N45, Ag 3p, O 1s, C 1s, Ar 2p, Ag 4p, and Ag 4s narrow scans were obtained. The sample analyzed is the standard instrument calibration silver foil mounted inside the analysis chamber of the K-Alpha. Sputtering with monoatomic Ar+ was performed prior to analysis to remove surface contamination. Narrow and survey scans were collected at 50 and 200 eV pass energy, respectively.

An end-to-end calibration of the Mini-EUSO detector in space

Mini-EUSO is a wide Field-of-View (44∘×44∘) telescope currently in operation from a nadir-facing Ultra-Violet (UV) transparent window in the Russian Zvezda module on the International Space Station (ISS). Mini-EUSO has been designed as a scaled-down version of the original JEM-EUSO telescope to raise its instrumentation’s technological readiness level and demonstrate its observational principle, while performing multidisciplinary studies on different fields such as atmospheric science and planetology. One of Mini-EUSO main goals is the study of the UV background for future space missions employing the same concept as the original JEM-EUSO telescope, which requires an absolute calibration of the Mini-EUSO instrument. During the past years, a few observational campaigns have been completed, employing a ground-based UV flasher to perform an end-to-end calibration of the instrument. In this paper, we present the assembled UV flasher system, the operation of the field campaign and the analysis of the obtained data. The results are interpreted by the means of a parametrization of the Mini-EUSO photon counts. The end-to-end efficiency of several pixels has been obtained, taking into account different parameters such as the atmospheric attenuation, the optics efficiency and the multi-anode photomultiplier detection efficiency.

Anticipatory climate policy mix pathways: a framework for ex-ante construction and assessment applied to the road transport sector

ABSTRACT Globally, climate policy implementation is failing to deliver on the ambitions outlined in the Paris Agreement and countries’ Nationally Determined Contributions. We argue that a more strategic and anticipatory approach to policy mix design and implementation can help contribute to realizing these ambitions. Policy mixes need to co-evolve as energy transitions progress, in order to effectively target multiple transition challenges as these change over time. Accordingly, policy assessments need to both consider interactions between instruments and adopt a dynamic perspective, in terms of design logics and evaluative criteria. We highlight the need for a construction and assessment methodology for designing policy mix pathways which explicitly considers durability risks which could weaken support and lead to dismantling, and anticipatory design principles which can help mitigate these risks. Our paper addresses this gap by proposing and illustrating a novel framework for policy instrument mix pathway construction and ex-ante assessment. We identify generalizable durability challenges for effective anticipatory design: dynamic cost effectiveness, the distributive impacts and acceptance of pathways, along with fiscal and governance requirements for effective implementation. We demonstrate the value of the approach by application to the German light-duty vehicle sector transition. We construct and comparatively assess three illustrative pathways promising to deliver the German LDV sector 2030 GHG targets. The pathways differ in logic, and which of three main market dynamics driving a diffusion-stage transition they emphasize: battery electric vehicle (BEV) purchase, vehicle stock usage, and internal combustion engine (ICE) vehicle scrappage. Accordingly, the pathways utilize different instrument combinations, design features and calibrations. We also assess the illustrative pathways and discuss trade-offs. We argue that this approach can help improve climate policy planning and implementation processes, and increase the likelihood attaining ambitious mitigation targets.

Choice of blood collection methods influences extracellular vesicles counts and miRNA profiling.

Circulating RNAs have been investigated systematically for over 20years, both as constituents of circulating extracellular vesicles (EVs) or, more recently, non-EV RNA carriers, such as exomeres and supermeres. The high level of variability and low reproducibility rate of EV/extracellular RNA (exRNA) results generated even on the same biofluids promoted several efforts to limit pre-analytical variability by standardizing sample collection and sample preparation, along with instrument validation, setup and calibration. Anticoagulants (ACs) are often chosen based on the initial goal of the study and not necessarily for the later EV and/or exRNA analyses. We show the effects of blood collection on EV size, abundance, and antigenic composition, as well on the miRNAs. Our focus of this work was on the effect of ACs on the number and antigenic composition of circulating EVs and on a set of circulating miRNA species, which were shown to be relevant as disease markers in several cancers and Alzheimer's disease. Results show that while the number of plasma EVs, their relative size, and post-fluorescence labeling profile varied with each AC, their overall antigenic composition, with few exceptions, did not change significantly. However, the number of EVs expressing platelet and platelet-activation markers increased in serum samples. For overall miRNA expression levels, EDTA was a better AC, although this may have been associated with stimulation of cells in the blood collection tube. Citrate and serum rendered better results for a set of miRNAs that were described as circulating markers for Alzheimer's disease, colon, and papillary thyroid cancers.

Reducing Instrumental Errors in Parkes Pulsar Timing Array Data

This paper demonstrates the impact of state-of-the-art instrumental calibration techniques on the precision of arrival times obtained from 9.6 yr of observations of millisecond pulsars using the Murriyang 64 m CSIRO Parkes Radio Telescope. Our study focuses on 21 cm observations of 25 high-priority pulsars that are regularly observed as part of the Parkes Pulsar Timing Array project, including those predicted to be the most susceptible to calibration errors. We employ measurement equation template matching (METM) for instrumental calibration and matrix template matching (MTM) for arrival time estimation, resulting in significantly improved timing residuals with up to a sixfold reduction in white noise compared to arrival times estimated using scalar template matching and conventional calibration based on the ideal feed assumption. The median relative reduction in white noise is 33%, and the maximum absolute reduction is 4.5 μs. For PSR J0437−4715, METM and MTM reduce the best-fit power-law amplitude (2.7σ) and spectral index (1.7σ) of the red noise in the arrival time residuals, which can be tentatively interpreted as mitigation of 1/f noise due to otherwise unmodeled steps in polarimetric response. These findings demonstrate the potential to directly enhance the sensitivity of pulsar timing array experiments through more accurate methods of instrumental calibration and arrival time estimation.

A smartphone-based multichannel magnetoelastic immunosensor for acute aortic dissection supplementary diagnosis

Some biomarkers of acute aortic dissection (AAD) can be used for the potential supplementary diagnosis of AAD, such as C-reactive protein (CRP), smooth muscle myosin heavy chain (SmMHC), and D-dimer (D-D). However, the current measurement methods for common markers primarily rely on sophisticated instruments. The operation process is complicated, and the reagents used are expensive. To provide chronic disease monitoring and home self-examination services for potential AAD patients in real time, we developed a smartphone-based multichannel magnetoelastic (ME) immunosensing device to detect protein levels. Our immunosensor reduced the aforementioned restrictions and demonstrated excellent performance for the supplementary diagnosis of AAD. In this paper, we successfully combined the intelligent terminal with the hardware system to sample the resonance frequency shift (RFS) on the multichannel ME immunosensor. According to the target detection objects with their respective antibodies in the immune binding response, multiple experiments were conducted to detect multiple groups of samples, and we found that a CRP concentration, a SmMHC concentration, and a D-D concentration in the range of 0.1−100μg/mL, 1−4ng/mL, and 0.25−5μg/mL were linearly proportional to the RFS of the ME immunosensor, respectively. For CRP, SmMHC, and D-D, the sensitivities were 13.37Hz/μg∙mL‐1, 155.19Hz/ng∙mL‐1, and 332.72Hz/μg∙mL‐1, respectively, and the detection limits were 2.634×10‐3μg/mL, 1.155×10‐2ng/mL, and 3.687×10‐3μg/mL, respectively. The experiments demonstrated that the accuracy and stability of our device were comparable to those of the vector network analyzer (VNA, Calibration instrument).

Intensity-energy response function of Al/Cr-K[formula omitted] x-ray photoemission instruments: An inter-laboratory study

The question of the intensity-energy response of photoemission spectrometers has been approached through a round-robin involving 13 instruments working with low (Al/Mg-Kα) and high (Cr-Kα) energy photon sources. An algorithm based on the analysis of inelastic background previously proposed [S. Guilet et al., J. Electron Spectrosc. Relat. Phenom. 285 (2022) 147225)] was intensively tested against calibrated Al/Mg-Kα instruments and calculated relative sensitivity factors (RSFs) over the 15 core level peaks of coinage metals (Ag, Au, Cu). In both cases, the linear correlation within ±10 %, over two orders of magnitude in intensity and for kinetic energies ranging from ∼400 to 1400eV, showed the consistency of the approach. All the contributions to RSFs (e.g. non-dipolar terms in the photo-ionization cross section, elastic scattering effects, surface excitations, beam polarization by the monochromator) were critically reviewed and taken into account using the state-of-the-art modellings and databases. Strong variations were evidenced among instruments, regarding not only the response functions, but also the theoretical RSFs due to different measurement geometries. For the Cr-Kα hard x-ray instruments, the same analysis was performed with a set of different materials (Al, Si, Ge, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, W, Au). A ±10 % satisfactory agreement against theoretical RSFs over 69 core levels spanning a large kinetic energy range (300–4000 eV) could be achieved with a common response function. Despite limitations that are reviewed, this work opens interesting perspectives for a systematic calibration of photoemission instruments.

Portable temperature-controlled permeation device for the generation of formaldehyde gas standard

Formaldehyde is a major indoor air pollutant. Accurate analysis of airborne formaldehyde is essential for effective monitoring and risk assessment. For many formaldehyde analysis techniques, the accuracy of the results depends on the calibration system. Existing formaldehyde calibration methods often face limitations, such as instability over time or limited concentration range. They also lack practicality for on-field calibration either because of bulkiness or because of high gas consumption. To address these challenges, a device using a paraformaldehyde permeation tube within a custom-built, temperature-controlled system was designed and evaluated.The device weighs less than 3 kg and operates using a nitrogen source. Its low gas consumption (30–100 mL min−1) enables the use of a portable gas cylinder of pure nitrogen (<2 kg) as gas supply. Formaldehyde concentrations ranging from 8.3 to 464 µg/m−3 were successfully generated, demonstrating the device’s versatility. A custom-built high-emission permeation tube could generate concentrations from 5 940 to 49 471 µg/m−3 using the same system. Additionally, the emission rate is independent of the flow rate and follows Antoine’s law with respect to temperature, enabling accurate prediction of concentration in various conditions over the evaluated range and beyond. Furthermore, the study confirms the long-term stability (1 year) of the low-emission paraformaldehyde permeation tube, with emission rates remaining mostly within ± 5 % of the average value for each temperature.The temperature-controlled permeation system approach enabled rapid stabilisation of formaldehyde generation at various concentrations and low flow rates, eliminating the need for additional dilution equipment and facilitating on-site instrument calibration at various gas concentrations. This reliable and efficient portable formaldehyde generator offers a valuable solution for field calibration, providing accurate and stable reference gas for diverse analytical needs.