Calibration Solutions Research Articles

Rotation Measure study of FRB 20180916B with the uGMRT

Context. Fast Radio Burst 20180916B is a repeating FRB whose activity window has a 16.34-day periodicity that also shifts and varies in duration with the observing frequency. Recent observations report that the FRB has started to show an increasing trend in secular Rotation Measure (RM) after only showing stochastic variability around a constant value of −114.6 rad m−2 since its discovery. RM studies let us directly probe the magnetic field structure in the local environment of the FRB. The trend of the variability can be used to constrain progenitor models of the FRB. Hence, further study of the RM variability forms the basis of this work. Aims. We studied the local environment of FRB 20180916B. We did so by focusing on polarization properties, namely RM, and studied how it varies with time. The data comes from the ongoing campaigns of FRB 20180916B using the upgraded Giant Metrewave Radio Telescope (uGMRT). The majority of the observations are in Band 4, which is centered at 650 MHz with 200 MHz bandwidth. Additionally, we used a few observations where we had simultaneous coverage in Band 4 and Band 5 (centered at 1100 MHz). Methods. We applied a standard single-pulse search pipeline to search for bursts. In total, we detected 116 bursts with ∼36 hours of on-source time spanning 1200 days from December 2020 to February 2024, with two bursts detected during simultaneous frequency coverage observations. We developed and applied a polarization calibration strategy suited for our dataset. On the calibrated bursts, we used QU-fitting to measure RM. We verified the veracity of calibration solution and RM measurement by performing RM measurements on single pulses of PSR J0139+5814. We also measured various other properties such as rate, linear polarization fraction, and fluence distribution. Results. Of the 116 detected bursts, we could calibrate 79 of them. We observed in our early observations that the RM continued to follow a secular linear trend, as already seen in past observations. However, our later observations suggest that the source switched from the linear trend to stochastic variations around a constant value of −58.75 rad m−2. It has ceased any secular variability and is only showing stochastic variability. Using the predicted Milky Way RM contribution, we report a tentative detection of a sign flip in the RM in the host galaxy host-frame. We also studied a cumulative rate against fluence and note that the rate at higher fluences (1.2 Jy ms) scales as γ = −1.09(7), whereas that at lower fluences (between 0.2 and 1.2 Jy ms) only scales as γ = −0.51(1), meaning the rate at the higher fluence regime is steeper than at the lower fluence regime. Finally, we qualitatively assess the two extremely large bandwidth bursts that we detected in our simultaneous multi-band observations. Conclusions. Future measurements of RM variations would help place stronger constraints on the local environment. Moreover, any periodic behavior in the RM measurements would directly test progenitor models. Therefore, we motivate such endeavors.

Statistics of Travelling Ionospheric Disturbances Observed Using the LOFAR Radio Telescope

A climatology of Travelling Ionospheric Disturbances (TIDs) observed using the LOw Frequency ARray (LOFAR) has been created based on 2,723 hours of astronomical observations. Radio telescopes such as LOFAR must contend with many causes of signal distortions, including the ionosphere. To produce accurate astronomical images, calibration solutions are derived to mitigate these distortions as much as possible. These calibration solutions provide extremely precise measurements of ionospheric variations across the LOFAR network, enabling TIDs to be detected which may be inaccessible to more traditional techniques. Waves are detected by LOFAR under all observing conditions, with no clear dependence on solar or geomagnetic activity. The vast majority of the observed waves travel in the opposite direction to the climatological thermospheric winds, suggesting that they are caused by upward propagating atmospheric gravity waves which are filtered by the wind. Waves of different periods display slightly different propagation directions, with waves of shorter periods consistent with the winds at lower altitudes within the thermosphere ($\SI{180}{\kilo\metre}$ for $10-\SI{15}{\minute}$ periods compared to $\SI{220}{\kilo\metre}$ for $20-\SI{27}{\minute}$ periods). This suggests that either the shorter period waves are being detected at lower altitudes or that they are simply more sensitive to the winds at lower altitudes. This indicates that observations made using LOFAR may enable the investigation of vertical coupling within the neutral atmosphere. The shortest period waves in the dataset ($<\sim\SI{10}{\minute}$) display distinct characteristics, suggesting they may be from a distinct population such as previously reported disturbances in the plasmasphere. The short period waves are compared to previous observations using other radio telescopes, showing that plasmaspheric disturbances likely account for some of the shortest period waves ($<\sim\SI{5}{\min}$) but there are still a large number of waves at these periods which are of uncertain origin.

Development of a Modular Virtual Calibration Platform for Power Machinery

The hardware-in-the-loop (HIL)-based virtual calibration technology for power machinery significantly enhances the efficiency and flexibility of electronic controller calibration, reducing dependency on physical experiments and lowering development costs. This paper presents an independently developed modular virtual calibration platform, designed based on the ISO/IEC 42010 architecture approach and the V-Model development process. The platform adopts a modular layered architecture comprising the physical layer, communication layer, model layer, software layer, and application layer. Each layer is independently developed and seamlessly integrated, ensuring excellent scalability and maintainability. Through performance validation conducted under steady-state and transient operating conditions of the diesel/natural gas dual-fuel engine electronic control unit (ECU), experimental results demonstrated that the platform possesses high computational accuracy, rapid response capability, and stable operation across different scenarios. The experiments validated that the platform can effectively replicate the real behavior of the controlled units in a virtual environment, confirming its adaptability and reliability. The platform offers an efficient and reliable solution for power machinery controller calibration.

Comparison of different characterization approaches for monoelemental calibration solutions at two national metrology institutes.

Monoelemental calibration solutions are the most common reference in elemental analysis, linking measurement results to the International System of Units (SI). National Metrology Institutes (NMI) prepare these solutions as certified reference materials (CRM) and determine their elemental mass fraction with high accuracy. Characterization with high accuracy is one of the most critical steps in CRM production. This report compares the approaches taken by the NMIs of Türkiye (TÜBİTAK-UME) and Colombia (INM(CO)) in preparing and characterizing cadmium calibration solutions with a nominal value of 1 g kg-1. Each NMI produced CRMs using an independent batch of cadmium calibration solution and assigned mass fraction values to both their own solutions and those of the other NMIs. TÜBİTAK-UME employed a primary difference method (PDM) to assess the purity of a cadmium metal standard, quantifying all possible impurities using a combination of instrumental analytical techniques. The defined purity standard was used for both the gravimetric preparation of the CRM and the calibration of high-performance inductively coupled plasma optical emission spectrometry (ICP-OES) measurements. On the other hand, INM(CO) used gravimetric titration with EDTA to assay cadmium in the CRM solutions. The EDTA salt was previously characterized by titrimetry. Despite the fundamentally different measurement methods and independent metrological traceability paths to the SI, the measurement results exhibited excellent agreement within the stated uncertainties. This comparative analysis demonstrates the effectiveness of varied characterization approaches and underscores the reliability of the cadmium calibration solutions prepared by TÜBİTAK-UME and INM(CO). This collaborative effort highlights the reliability and adaptability of various measurement techniques in fulfilling rigorous metrological standards for elemental calibration solutions. Furthermore, this approach enhances the robustness of the measurements in the field of elemental analysis and contributes traceability to the SI.

Simulation Study Based on the Influencing Factors of Vibrating Screen Screening Efficiency

Based on the vibrating screening simulation technology is an efficient technology to carry out research on sieving theory and sieving mechanism, which plays an irreplaceable role in promoting the rapid development of vibrating screen, the existing research direction of vibrating screening technology is introduced, the current status of research on the simulation method of the factors affecting the sieving effect in the vibrating sieving process and the current status of the application is elaborated, and the conclusions are summarized, and finally it is pointed out that the vibrating screen sieving efficiency simulation The future development direction of the research is: the combination of simulation technology and artificial intelligence, big data and other technologies will further promote the intelligent development of screening technology. The opportunities and challenges are: the simulation software will continue to improve, providing a more friendly user interface and more powerful computing power. Artificial intelligence technology will provide new solutions for parameter calibration, model simplification and result analysis.

Key comparison CCQM-K78.b - non-polar analytes in organic solvent: methoxychlor and trifluralin in acetonitrile

Main textThe CCQM-K78.b key comparison was coordinated by the Bureau International des Poids et Mesures (BIPM) on behalf of the CCQM Organic Analysis Working Group (OAWG) of the 'Comité Consultatif pour la Quantité de Matière' (CCQM), for National Measurement Institutes (NMIs) and Designated Institutes (DIs) providing measurement services in organic analysis under the 'Comité International des Poids et Mesures' (CIPM) Mutual Recognition Arrangement (MRA).This key comparison was conducted as a 'Track A' comparison within the OAWG's 10-year strategic plan. The goal of CCQM-K78.b was to underpin capabilities for the value assignment of calibration solutions containing low polarity/non-polar organic analytes in organic solvents. The selected model system consisted of a two-component pesticide solution in acetonitrile, comprising methoxychlor and trifluralin.Participants were tasked with assigning the mass fractions, in units of μg/g, of methoxychlor and trifluralin in acetonitrile solution. The mass fraction levels and analytical challenges of the selected analytes were representative of those encountered for calibration solutions of non-polar organic analytes. Participation in CCQM-K78.b allowed for the benchmarking of capabilities for assigning the mass fraction of non-polar organic compounds (pKow < -2) in solution, at mass fractions above 5 μg/g, in an organic solvent. Additionally, the comparison assessed the capabilities for the quantitative assignment of thermally labile compounds.Participants were provided by the BIPM with ampoules containing methoxychlor and trifluralin in acetonitrile. Each participant reported the mass fraction content of each analyte in μg/g. All participants ensured the metrological traceability of their results through the use of a Primary Reference Material (PRM), which was used to prepare a primary calibrator solution for each analyte using a gravimetric procedure. The twenty participating institutes primarily used analysis procedures based on GC-MS, -IDMS, -MS/MS, -ECD, and -FID, with some participants also using LC-UV for the value assignment.The analysis of methoxychlor and trifluralin in acetonitrile solution presented several challenges, including the thermal stability of the analytes under selected analytical techniques, control of solvent volatility, and considerable variation in some results using MS-based quantification methods. The mass fraction assignments for methoxychlor and trifluralin, consistent with the key comparison reference values (KCRVs), were achieved with associated relative standard uncertainties of (0.38 - 2.9) % for methoxychlor and (0.35 - 2.5) % for trifluralin.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Enhancing pointing accuracy in Risley prisms through error calibration and stochastic parallel gradient descent inverse solution method

Enhancing pointing accuracy in Risley prisms through error calibration and stochastic parallel gradient descent inverse solution method

Atomic absorption and inductively coupled plasma atomic emission determination of iron and manganese in medicinal salt mixtures

Complete extraction of analytes from samples and the homogeneity of analyzed solutions were achieved using ultrasonic treatment (20 minutes). The sensitivity, precision, and accuracy of atomic absorption determination of analytes were improved by using Triton X-100 (4%) and calibration solutions based on iron and manganese acetylacetonates. It was demonstrated that sensitivity increased by 1.7 times for manganese and 1.5 times for iron. The iron and manganese content in medicinal salt mixtures was determined using both atomic absorption and inductively coupled plasma atomic emission methods. The results obtained by these two independent methods were compared, showing that the dispersions are homogeneous and the variation in results is minor, attributed to random error. The accuracy of the atomic absorption results was verified using the standard addition method and by varying the sample weight, confirming that systematic error is negligible. The detection limits established by the atomic absorption method were Cmin=0.009 g/mL for iron (Cmin, lit=0.015 g/mL) and Cmin=0.003 g/mL for manganese (Cmin, lit=0.004 g/mL).

Microseismicity-Based Modelling of Induced Fracture Networks in Unconventional Reservoirs

A single planar hydraulic fracture is typically the primary component used to simulate hydraulic fracturing stimulation in conventional reservoirs. However, in ultra-low-permeability shale reservoirs, a large system of fracture networks must be generated to produce hydrocarbons economically. Therefore, traditional modeling approaches centered on single planar fractures are inadequate for accurately representing the intricate geometry and behavior of fractures in these reservoirs. In previous works, 2D fractal fracture networks (FFNs) have been used to generate sets of hydraulic and natural fractures based on microseismic event (MSE) data. Since microseismic data are retrieved in 3D space, the aforementioned model cannot accurately represent induced fracture properties. The objective of this paper is to study in detail the recently developed 2D FFN model and propose a novel solution by expanding the previous model to accommodate real 3D microseismic data. First, the definitions of the 2D FFN model are described, and associated calibration mechanisms are proposed. Next, the 3D FFN model and its calibration system are demonstrated. While the novel 3D calibration solution utilizes an identical matching concept to the 2D methodology, the residual distances between the nodes and the MSE are calculated in 3D spaces. Finally, a set of real microseismic data are used to calibrate the generation of 3D fractals using the proposed workflow. The interactions between microseismicity and fractured reservoir dynamics are represented through the integration of fractal fracture models and microseismic data. This work contributes to advancing the current understanding of hydraulic fracturing in unconventional reservoirs and provides a valuable framework for improving fracture modeling’s accuracy in reservoir engineering applications.

Phased Array Antenna Calibration Based on Autocorrelation Algorithm.

The problem of calibrating phased array antennas in a noisy environment using an autocorrelation algorithm is investigated and a mathematical model of the autocorrelation calibration method is presented. The proposed calibration system is based on far-field scanning of the phased array antenna in an environment with internal noise and external interference. The proposed method is applied to a phased array antenna and compared with traditional rotating-element electric-field vector methods, which involve identifying the maximum and minimum vector-sum points (REVmax and REVmin, respectively). The proposed calibration system is verified for a phased array antenna at 3 GHz. Experimental verification of the mathematical model of the proposed method demonstrates that the autocorrelation method is more accurate than the rotating-element electric-field vector methods in determining the amplitude and phase shifts. The measured peak gain of the combined beam in the E-plane increased from 7.83 to 8.37 dB and 3.57 to 4.36 dB compared to the REVmax and REVmin methods, respectively, and the phase error improved from 47° to 55.48° and 19.43° to 29.16°, respectively. The proposed method can be considered an effective solution for large-scale phase calibration at both in-field and in-factory levels, even in the presence of external interference.

A novel high-dimensional sensor calibration framework integrating thermodynamic laws in complex HVAC systems

Accurate calibration of sensors is critical for ensuring energy efficient operation of Heating, Ventilation, and Air Conditioning (HVAC) systems in buildings. Due to the high dimensionality of sensor data and the complexity of multiple-fault scenarios, calibrating sensors in large and complex HVAC systems presents significant challenges. To address this issue, this study introduces a novel sensor calibration framework that integrates thermodynamic laws for high-dimensional sensor calibration in complex HVAC systems. The traditional calibration method heavily relies on accurate data, making it difficult to apply in practical engineering projects. The innovative aspect of our method lies in its integration of thermodynamic laws, such as mass balance and energy conservation, with sensor calibration framework. This approach enables the framework to handle high-dimensional sensor measurements effectively without any training data. We compared five optimization algorithms and applied them to a central cooling system in Hong Kong. The results demonstrated that the simulated annealing (SA) is the most robust for solving the calibration problem, even in scenarios with up to 21 faulty sensors, with the calibrated sensor accuracy meeting the standards for conventional chiller plant operations. This novel framework provides a robust and reliable solution for high-dimensional sensor calibration in large and complex HVAC systems, addressing the growing need for precise sensor calibration as the number of installed sensors increases.

Online Calibration for Networked Radar Tracking of UAS

The need for effective tracking mechanisms of small unmanned aircraft systems (sUAS) has become crucial as their use has increased in populated areas. This paper presents a practical tracking solution for sUAS using a network of phased array radars. Achieving optimal system performance while tracking the sUAS requires extrinsic calibration of the individual radar systems to a common frame of reference. We propose a straightforward calibration solution based upon the orthogonal Procrustes formulation that uses radar measurements from ground-mounted radar associated with real-time-kinematic global positioning system (RTK-GPS) data. Two variations of the calibration are provided: a batch processing method, and an online method for real-time adjustments. This paper provides a practical analysis of the advantages and disadvantages associated with both calibration methods. This assessment of the calibration methods, along with an evaluation of the radar network’s sUAS tracking ability, is validated by simulation studies and hardware tests. The hardware experiments especially provide valuable insights into the practical implications of the proposed tracking solution.

Colorimetric Determination of Dissolved Oxygen: Assessment of Methodological Influences on Iodine Spectra, Isosbestic Point, Precision and Accuracy.

The colorimetric method for determining dissolved oxygen concentrations in freshwater and seawater samples essentially relies on measuring the absorbance of released I2 and I3 - in a mixed form. While this approach is relatively quick and convenient, it is susceptible to significant temperature effects during analysis, irrespective of field temperatures. Additionally, the influences of spectrophotometric absorbance wavelengths and iodine concentrations on oxygen concentration determinations are ambiguous. We found that, while iodine concentration and absorbance wavelength impart minor influences, temperature changes during sample analysis alter the fractionation of two major iodine species (I2 and I3 -) and affect their spectra, with the latter effect imparting the greatest influence on oxygen concentrations. An empirical molar extinction coefficient was defined for the mixture (consisting of 96% I3 - and 4% I2), yielding values of 2282, 1115, and 792 M-1 cm-1 at 25 °C at the most commonly used wavelengths of 430, 456, and 466 nm, respectively. Altering the temperature led to variances in absorbance by 0.33%, 0.42%, and 0.51% °C-1 at 430, 456, and 466 nm, respectively. Therefore, for absorbances measured at 456 nm, a room temperature correction can be applied to the empirical molar coefficient by 1115 M-1 cm-1 × [1 + (room temperature - 25 °C) × 0.0042]. Reducing room temperature differences between samples and calibration solutions became the most important factor in maintaining the precision and accuracy of the measurement. With these precautions, a precision of ∼0.2% (coefficient of variation) over the normal surface water oxygen concentration of around 250 μM can be readily achieved at all tested wavelengths. This method offers a linear oxygen concentration range of 0-650 μM.

An accurate measurement method for serum homocysteine measurement by ID-LC/MS/MS and the application of external quality assessment

BackgroundSerum homocysteine (Hcy) measurement accuracy is essential for detecting and diagnosing cardio-cerebrovascular illnesses. Although many different methods have been developed to determine the concentration of Hcy, those different assays showed nonequivalent results. This study aimed to develop an accurate and precise isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS) method for serum homocysteine (Hcy) and assign values for reference materials used in external quality assessment (EQA) programs. MethodsDifferent concentrations of homocysteine calibration solutions were prepared with d4-Hcy as the internal standard. This method employed DTT to reduce protein-bound Hcy, followed by protein precipitation, and gradient elution on a Supelcosil LC-CN column for chromatographic separation, and multiple reaction monitor (MRM) mode with electrospray ionization (ESI) for mass spectrometric detection. After optimized ID-LC/MS/MS parameters, imprecision, trueness, the limit of quantification (LoQ), the limit of detection (LoD), and measurement uncertainty were evaluated to check the methodological performance. The established method was employed in assigning values to EQA samples, which were sent to 63 clinical laboratories in Beijing to measure Hcy. ResultsAt 10.69,15.99, and 37.80 μmol/L levels, the present method demonstrated analytical imprecision of 0.57 %, 0.65 %, and 0.57 %, and recoveries of 99.67 % to 100.21 %, respectively. The bias between the target values of GBW (Guojia Biaozhun Wuzhi) were − 0.79 % to 0.62 %. The LoQ and LoD for Hcy were 0.36 nmol/L and 0.27 nmol/L. The method had an uncertainty (U 95 %) of 1.34 % to 1.48 %. For the three levels of EQA samples, the percentage of laboratories meeting the trueness evaluation criteria (±10 %) was 81.67 %, 83.33 %, and 71.67 % respectively. ConclusionsWith optimal method precision and trueness, the ID-LC/MS/MS method to measure serum Hcy can be used for value assignment of EQA samples, which can provide reliable data for monitoring the accuracy of clinical laboratory for Hcy measurement.

Solvent-Based and Matrix-Matched Calibration Methods on Analysis of Ceftiofur Residues in Milk and Pharmaceutical Samples Using a Novel HPLC Method.

The matrix effect is accepted as one of the critical factors that affect trueness, and it is especially important in the analysis of critical compounds, such as drugs, toxins and pesticides, in complex matrices. Ceftiofur (CEF) is a leading drug used in dairy industry for pulmonary infections. Because milk has a complex matrix, which is rich in fats, proteins and many other compounds, the determination of CEF in milk products deals with issues of trueness. On the other hand, pharmaceuticals also have a complex composition as they contain not only the active pharmaceutical ingredient but also many excipients, such as preservatives and pH modifiers. Due to its frequent use, its residues can be found in meat products or exist as an excreted compound in urine, milk and so on. The aim of this study was to investigate the effect of different calibration methods on quantitative estimation of CEF in milk and pharmaceutical samples. CEF was analysed using a new HPLC method, in which separation was achieved on a C18 bonded fused-core silica particle column by using isocratic elution; the method was optimized by testing different chromatographic conditions and validated according to the ICH Q2(R1) and United States Pharmacopeia guidelines. Interestingly, it was found that CEF signals in milk samples were higher than the ones at the same level prepared in calibration solutions with a ratio of 11.28:1. This finding reveals the necessity of matrix-matched calibration for accurate quantitative determination of CEF in milk samples. Moreover, the milk in the market and the most used pharmaceutical formulations were analysed using the current method.

Mitigating calibration errors from mutual coupling with time-domain filtering of 21 cm cosmological radio observations

Abstract The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation (EoR). This has led to the construction of low-frequency radio interferometric arrays, such as the Hydrogen Epoch of Reionization Array (HERA), aimed at systematically mapping this emission for the first time. Precision calibration, however, is a requirement in 21 cm radio observations. Due to the spatial compactness of HERA, the array is prone to the effects of mutual coupling, which inevitably lead to non-smooth calibration errors that contaminate the data. When unsmooth gains are used in calibration, intrinsically spectrally-smooth foreground emission begins to contaminate the data in a way that can prohibit a clean detection of the cosmological EoR signal. In this paper, we show that the effects of mutual coupling on calibration quality can be reduced by applying custom time-domain filters to the data prior to calibration. We find that more robust calibration solutions are derived when filtering in this way, which reduces the observed foreground power leakage. Specifically, we find a reduction of foreground power leakage by 2 orders of magnitude at k∥ ≈ 0.5 h Mpc−1.

Robust and efficient calibration method of liquid-crystal spatial light modulator based on the linear combination strategy

Abstract Phase-only spatial light modulators (SLMs) play a vital role in virous fields. However, its modulation accuracy is compromised by the static aberration and the phase response nonlinearity. To enhance the modulation accuracy, this paper presents an innovative full calibration method for SLMs, effectively addressing both static aberration and nonlinear phase responses using only two shots of camera. The main highlight of this paper is the binding of a novel linear combination strategy and a unique kinoform. This binding can eliminate phase distortion between two shots of camera, making our method dramatically robust in correcting phase response nonlinearity. Additionally, benefit from the accurate correction of phase response nonlinearity, the static aberration is accurately compensated by the single-shot spatial carrier phase-shifting technology. In conclusion, the proposed method's strong robustness, precision, and efficiency position it as an ideal solution for SLM calibration.&amp;#xD;

Measurement method of flexible component pose based on discrete motion actuators

Abstract In order to address the limitations of traditional large discrete motion actuator mechanisms in realizing high-precision inter-axis relationship calibration in manufacturing environments, this paper proposes a new convolutional neural network-based attitude mapping estimation method, component pose using convolutional neural network (CPCNN). The method implicitly encodes the inter-axis relation matrix into the weight parameters of the training neural network, which results in a high degree of integration with existing large discrete motion actuator mechanisms. The CPCNN-based method directly obtains the attitude change of the adjustment cabin by reading the change of each axis of the current motion actuator mechanism in its own coordinate system. This method can overcome the limitations of the experimental process in the traditional calibration methods and improve the accuracy of attitude mapping under the influence of self-weight by selecting better motion parameters through redundant degrees of freedom. The application of this new method will provide an effective solution for the high-precision inter-axis relationship calibration of large discrete motion actuator mechanisms in manufacturing environments, offering new possibilities for improving production efficiency and product quality.

Stereo Bi-Telecentric Phase-Measuring Deflectometry.

Replacing the endocentric lenses in traditional Phase-Measuring Deflectometry (PMD) with bi-telecentric lenses can reduce the number of parameters to be optimized during the calibration process, which can effectively increase both measurement precision and efficiency. Consequently, the low distortion characteristics of bi-telecentric PMD contribute to improved measurement accuracy. However, the calibration of the extrinsic parameters of bi-telecentric lenses requires the help of a micro-positioning stage. Using a micro-positioning stage for the calibration of external parameters can result in an excessively cumbersome and time-consuming calibration process. Thus, this study proposes a holistic and flexible calibration solution for which only one flat mirror in three poses is needed. In order to obtain accurate measurement results, the calibration residuals are utilized to construct the inverse distortion map through bicubic Hermite interpolation in order to obtain accurate anchor positioning result. The calibrated stereo bi-telecentric PMD can achieve 3.5 μm (Peak-to-Valley value) accuracy within 100 mm (Width) × 100 mm (Height) × 200 mm (Depth) domain for various surfaces. This allows the obtaining of reliable measurement results without restricting the placement of the surface under test.

The Thermal Structure and Composition of Jupiter's Great Red Spot From JWST/MIRI

AbstractJupiter's Great Red Spot (GRS) was mapped by the James Webb Space Telescope (JWST)/Mid‐Infrared Instrument (4.9–27.9 m) in July and August 2022. These observations took place alongside a suite of visual and infrared observations from; Hubble, JWST/NIRCam, Very Large Telescope/VISIR and amateur observers which provided both spatial and temporal context across the jovian disc. The stratospheric temperature structure retrieved using the NEMESIS software revealed a series of hot‐spots above the GRS. These could be the consequence of GRS‐induced wave activity. In the troposphere, the temperature structure was used to derive the thermal wind structure of the GRS vortex. These winds were only consistent with the independently determined wind field by JWST/NIRCam at 240 mbar if the altitude of the Hubble‐derived winds were located around 1,200 mbar, considerably deeper than previously assumed. No enhancement in ammonia was found within the GRS but a link between elevated aerosol and phosphine abundances was observed within this region. North‐south asymmetries were observed in the retrieved temperature, ammonia, phosphine and aerosol structure, consistent with the GRS tilting in the north‐south direction. Finally, a small storm was captured north‐west of the GRS that displayed a considerable excess in retrieved phosphine abundance, suggestive of vigorous convection. Despite this, no ammonia ice was detected in this region. The novelty of JWST required us to develop custom‐made software to resolve challenges in calibration of the data. This involved the derivation of the “FLT‐5” wavelength calibration solution that has subsequently been integrated into the standard calibration pipeline.