Calibration Of Response Research Articles

Achievement of 0.005% combined transfer uncertainties in the NIST detector calibration facility

Improvements in a lamp-monochromator-based facility at the National Institute of Standards and Technology (NIST), the Visible near-infrared Spectral Comparator Facility (VisSCF) which is used to calibrate optical detectors for spectral radiant power responsivity from 300 nm to 1100 nm, are described. These changes include extending the VisSCF operational range down to 300 nm from 350 nm, thereby fully covering the ultraviolet-A (UVA) spectral region and partially covering the UVB range. These improvements have lowered the magnitudes of most of the components in the uncertainty budget and have led to combined 0.005% transfer (k = 1) uncertainties in the spectral power responsivity calibrations over most of the spectral range. Redevelopment of the uncertainty budget results in total expanded uncertainties of spectral responsivities of less than 0.1% (k = 2) over the spectral range from 380 nm to 980 nm, with the greatest uncertainty term coming from the calibrations of the transfer standards.

Particularities of pyroelectric detectors in absolute measurements of chopped radiation shown for the example of a spectral responsivity calibration in the near- and mid-infrared spectral range at two primary radiometric standards

Abstract. The Physikalisch-Technische Bundesanstalt (PTB) expanded its capabilities for the calibration of the spectral responsivity s(λ) in the spectral range between 1.5 µm and 14 µm, traceable to the International System of Units (SI), with pyroelectric detectors as transfer standards. The pyroelectric transfer standards were calibrated absolutely against two independent primary radiometric standards, regarding their spectral responsivity s(λ). The first approach uses infrared laser sources at one of the PTB's cryogenic substitution radiometer facilities, which is a primary detector standard for the measurement of radiant power. The second approach uses a blackbody radiator with a temperature of about 1200 K, whose radiation can be calculated by Planck's law and is, in addition, spectrally selected by accurately characterized optical bandpass filters. Due to their measurement principle, pyroelectric detectors can only measure temporal changes in the input radiant power and are, therefore, operated with a chopper wheel to chop the incident radiation. The detector signal, which is typically measured with a lock-in amplifier, depends not only on the amplitude but also on the temporal shape of the chopped radiant power. It is shown that the calculation of the radiant power used for the determination of the spectral responsivity must be based on an accurate approximation of the temporal shape of the chopped radiant flux at the detector. This shape is different for both applied primary methods. It is further shown that the particularities of the lock-in-technique have to be considered in the calculation of the spectral responsivity, including the correct calculation of the detector signal. The results of the calibration with both approaches are consistent, and the realized measurement uncertainty is in the range between 1 % and 14 %. The pyroelectric detectors were thereby established as transfer detectors for the SI traceable measurement of radiant power in the near-infrared (NIR) and mid-infrared (MIR).

Construction, Characterization and Measurement of Fe\u2013C and Pd\u2013C HTFPs at CEM

The current state of the art for temperature realization and dissemination above 1300 K is through the MeP-K-19 [1]. A limited set of high-temperature fixed points (HTFPs), an essential component of the MeP-K-19, has their temperature determined (Co–C (1597 K), Pt–C (1011 K) and Re–C (2747 K)). It is really a need to increase the HTFPs available for realization and dissemination of the high-temperature MeP-K. Fe–C (1426 K) and Pd–C (1765 K) has been less investigated, their thermodynamic temperature hasn’t been definitively determined, and they have been considered good candidates for their inclusion in the MeP-K in the EMPIR project “Real-K” [2]. This paper describes the construction, characterization, and measurement of HTFPs of Fe–C and Pd–C at Centro Español de Metrología as part of its contribution to the EMPIR project “Real-K”. Cells made have hybrid-type crucibles and they have been filled applying the piston method. A series of 6 HTFPs has been constructed: 3 Fe–C and 3 Pd–C. Points of inflection of the melting plateaux are repeatable after several initial measurement cycles. Their corresponding International Temperature Scale (ITS-90) temperatures (t90), referenced to a Cu fixed point, and thermodynamic temperatures (t), by means of the spectral responsivity calibration, have been calculated. Additionally, the influence of the furnace in the temperature assigned to the cells has been determined for different furnaces types (one zone and three zone) and different temperature profiles.

Calibration of a stress-strain response for geopolymer concrete under axial compressive load

The use of geopolymer concrete (GPC) in common load-bearing structures is still limited, mainly due to the lack of specific design procedures and limited understanding of the stress–strain behavior under uniaxial loading. The present work investigates the mechanical responses of GPC under axial compressive load by conducting a large number of experiments. For this purpose, 198 samples with three GPC mixes were designed, including concrete grades of 30, 40, and 50 MPa. The samples were prepared following the ASTM standards to determine the stress–strain relationship under compression. The results showed that fly ash-based GPC had average elastic modulus values of 30.424, 31.497, and 33.650 GPa, respectively, for G30, G40, and G50, lower than estimated using formulae for Ordinary Portland Cement (OPC) concrete, such as ACI standard 318-11, AASHTO-2007, and others. Furthermore, a novel model of GPC stress–strain response was proposed, mainly based on the empirical formulation suggested by Sargin using a modified factor D. Besides, the deformation of GPC was observed larger than that of OPC with similar strength, for instance, the strain at peak stress [Formula: see text]. The GPC was also found to have better plasticity behavior than OPC while conducting the axial stress–strain response, with the obtained values of [Formula: see text]. The findings of this work might lead to additional in-depth research into GPC's mechanical characteristics, particularly its structural behavior.

Using Willingness to Pay and Willingness to Accept to Value Farmland Preservation under Ambiguous Property Rights and Preference Uncertainty

We use a paired-sample binary choice experiment to estimate willingness to pay (WTP) and willingness to accept (WTA) values when land is converted from agriculture to developed uses in Alberta, Canada. Validated principles for stated preference are followed in scenario design, elicitation format, experimental design, and ancillary questions. Preference uncertainty is addressed through alternative calibration of uncertain responses. Reliability and incentive compatibility measures indicate that respondents found both WTP and WTA scenarios to be plausible and incentive compatible. WTA-WTP value gaps are smaller than most previous studies, with consequentiality increasing WTA, WTP, and the gap between WTA and WTP.

Testing new analytical expression for dose response curves originating from the OTOR model

The possibility of precisely evaluating the equivalent beta dose in stimulated luminescence dating depends on the ability to fit the constructed dose response calibration curve with appropriate analytical expressions. There are a number of such expressions which successfully fit the dose response calibration curves. In the present study we use the recently developed analytical Pagonis-Kitis-Chen equation (PKC equation) to describe the dose response curves from a set of single-grain experimental data for a sedimentary sample from the Haua Fteah Cave in Libya. The PKC equation describes in analytical form the rate of filling of the electron traps during the irradiation stage in the one trap one recombination center model (OTOR). A detailed comparison was carried out between the PKC equation and two very successful equations existing in literature. The comparison criteria were the values of: (a) the reduced chi squared, (b) figure of merit, (c) Equivalent dose and (d) the possible physical meaning of the coefficients used as the free fitting parameters during the fitting procedure. The results show that the PKC equation is at least equally successful as the other two equations in fitting the experimental data.

Frequency dependence on polarization switching measurement in ferroelectric capacitors

Ferroelectric hysteresis loop measurement under high driving frequency generally faces great challenges. Parasitic factors in testing circuits such as leakage current and RC delay could result in abnormal hysteresis loops with erroneous remnant polarization (P r) and coercive field (E c). In this study, positive-up-negative-down (PUND) measurement under a wide frequency range was performed on a 10-nm thick Hf0.5Zr0.5O2 ferroelectric film. Detailed analysis on the leakage current and RC delay was conducted as the polarization switching occurs in the FE capacitor. After considering the time lag caused by RC delay, reasonable calibration of current response over the voltage pulse stimulus was employed in the integral of polarization current over time. In such a method, rational P–V loops measured at high frequencies (>1 MHz) was successfully achieved. This work provides a comprehensive understanding on the effect of parasitic factors on the polarization switching behavior of FE films.

New facility for primary calibration of differential spectral responsivity of solar cells using LDLS-based monochromatic source

A newly established setup for primary calibration and characterization of solar cells at NMCC/SASO is presented. This differential spectral responsivity (DSR) measurement instrument uses laser-driven light source (LDLS)-based modulated (AC) source to measure the spectral responsivity of photovoltaic (PV) detectors and solar cells. The setup is intended for measuring the spectral responsivity in the wavelength range from 250 nm to 2000 nm, bias level up to 1.5 kW/m2, with which a measurement uncertainty of 1.06 % (k = 2, in the range of 300 nm to 900 nm) could be achieved. We present validation measurements as well as spectral responsivity and external quantum efficiency (EQE) measurements of reference solar cells to demonstrate the objective of the setup. We present a preliminary evaluation of the associated uncertainty components as well as an uncertainty budget for validation, optimization and standardization of our setup.

Calibration and recalibration of stress response systems across development: Implications for mental and physical health.

Decades of human and animal research demonstrates that stress responsive neuroendocrine systems calibrate to the harshness of environmental conditions during fetal and early postnatal life. Emerging evidence indicates that if conditions change markedly over childhood, the hypothalamic pituitary adrenal (HPA) axis may recalibrate during puberty, another period that involves heightened neural plasticity and rapid maturation of neurobehavioral systems. These recent findings have prompted increased interest in the potential for stress system calibration/recalibration over development. To direct research in this area, this chapter integrates and discusses theoretical perspectives and empirical evidence pertaining to calibration and recalibration of the stress response. We describe how these concepts relate to other constructs, including sensitive periods, plasticity, and programming. We then consider four potential periods of calibration/recalibration: fetal, infancy, puberty, and pregnancy/lactation. In each section, we discuss evidence that the HPA and/or sympathetic medullary adrenal (SAM) system undergoes developmental change, rendering it more plastic and amenable to shift its activity in response to environmental conditions. We also review findings that the impacts of environmental harshness on stress responding persist beyond these periods. We then articulate that marked change in the quality of the environment (from harsh to benign or vice versa) is required in order for recalibration to occur, and that recalibration would result in shifts in stress responding to more closely align with the profiles of individuals who have experienced these conditions throughout life. Finally, we reflect on whether recalibration of the HPA and SAM system may extend to the other stress-responsive neurobehavioral systems.

Estimating the VIIRS Thermal Emissive Band Response Versus Scan (RVS) and Calibration Offsets Using On-Orbit Pitch Maneuver Data

The Visible Infrared Imaging Radiometer Suite (VIIRS) is onboard the Suomi National Polar-orbiting Partnership (S-NPP) and the National Oceanic and Atmospheric Administration - 20 (NOAA-20) satellites. This study presents a method for estimating VIIRS Thermal Emissive Bands (TEB) Response Versus Scan (RVS) and calibration offsets simultaneously using on-orbit pitch maneuver data (METHOD2021). Raw Earth View (EV) RVS is estimated using an existing method (METHOD2019), with prelaunch RVS and calibration offsets as first guesses. Errors in the calibration offset are derived based on a prelaunch data-based assumption. Moreover, RVS and calibration offsets are optimized iteratively using the updated calibration coefficients until results converge. Compared to the METHOD2019, the METHOD2021 derived RVS is not affected by errors in the calibration offsets. Evaluation results using independent co-located Cross-track Infrared Sounder (CrIS) observations indicate that the METHOD2021 could effectively mitigate NOAA-20 scan angle and scene temperature dependent biases in M15-M16 and I5, as well as the cold bias in S-NPP M15. S-NPP TEB striping at cold scene temperatures can also be significantly reduced. Furthermore, NOAA-20 I5 and M15 measurements become more in family with S-NPP VIIRS and other radiometers at extremely low temperatures. Our analysis indicates that the impacts of the METHOD2021 and METHOD2019 on TEB SDRs are generally comparable. The METHOD2019 is simpler, while the METHOD2021 better explains the root causes of the VIIRS TEB scan angle and scene temperature dependent biases. Both can be used for improving VIIRS TEB on-orbit calibration, especially at cold scenes.

RSCNet: A Residual Self-Calibrated Network for Hyperspectral Image Change Detection

Deep learning-based methods (e.g., convolutional neural network (CNN)-based methods), have shown increasing potential in hyperspectral image (HSI) change detection (CD). However, the recent advances in CNN-based methods in HSI CD tasks are mostly devoted to designing more complex architectures or adding additional hand-designed blocks. This increases the number of parameters making model training difficult. In this paper, we propose an end-to-end residual self-calibrated network (RSCNet) to increase the accuracy of HSI CD. To fully exploit the spatial information, the proposed RSCNet method adaptively builds inter-spatial and inter-spectral dependencies around each spatial location with fewer extra parameters and reduced complexity. Moreover, the introduced self-calibrated convolution (SCConv) helps to generate more discriminative representations by heterogeneously exploiting convolutional filters nested in the convolutional layer. The designed RSC module can explicitly incorporate richer information by introducing response calibration operation. The experiments on four bi-temporal HSI datasets demonstrated that the proposed RSCNet method is more accurate than ten widely used benchmark methods.

Responsivity Calibration Technology for Pyroelectric Terahertz Detector

Responsivity Calibration Technology for Pyroelectric Terahertz Detector

Color Alignment for Relative Color Constancy via Non-Standard References.

Relative colour constancy is an essential requirement for many scientific imaging applications. However, most digital cameras differ in their image formations and native sensor output is usually inaccessible, e.g., in smartphone camera applications. This makes it hard to achieve consistent colour assessment across a range of devices, and that undermines the performance of computer vision algorithms. To resolve this issue, we propose a colour alignment model that considers the camera image formation as a black-box and formulates colour alignment as a three-step process: camera response calibration, response linearisation, and colour matching. The proposed model works with non-standard colour references, i.e., colour patches without knowing the true colour values, by utilising a novel balance-of-linear-distances feature. It is equivalent to determining the camera parameters through an unsupervised process. It also works with a minimum number of corresponding colour patches across the images to be colour aligned to deliver the applicable processing. Three challenging image datasets collected by multiple cameras under various illumination and exposure conditions, including one that imitates uncommon scenes such as scientific imaging, were used to evaluate the model. Performance benchmarks demonstrated that our model achieved superior performance compared to other popular and state-of-the-art methods.

Fast and simple calibration of frequency response and IQ skew for a coherent optical transmitter using a low-bandwidth photodetector.

A fast, precise, and low-cost coherent optical transmitter calibration scheme is proposed that uses multi-tone signals of a novel, to the best of our knowledge, design with unequal frequency intervals. With a single measurement, the proposed scheme can simultaneously calibrate the frequency response and the IQ skew of the transmitter using only a low-bandwidth photodiode. Simulation and experimental results indicate that the measurement error in the frequency response and coherent transmitter (Tx) skew is less than 0.3 dB and 0.2 ps, respectively. The feasibility of the proposed scheme is verified by an experiment involving 25 Gbaud 16-quadrature amplitude modulation (QAM) signal transmission using a Kramers-Kronig (KK) receiver. With the help of this calibration method, the measured bit error ratio performance was increased from 1.77e-2 to 3.52e-3 when the received optical power was -8 dBm.

JUNO Oscillation Physics

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton multi-purpose liquid scintillator detector with an expected energy resolution, under construction in a 700 m underground laboratory in the south of China (Jiangmen city, Guangdong province). The exceptional energy resolution and the massive fiducial volume of the JUNO detector offer great opportunities for addressing many essential topics in neutrino and astroparticle physics. JUNO’s primary goals are to determine the neutrino mass ordering and precisely measure the related neutrino oscillation parameters. With six years of data taking with reactor antineutrinos, JUNO can determine the mass ordering at a 3-4σ significance and the neutrino oscillation parameters sin2 θ 12, , and to a precision of better than 0.6%. In addition, the atmospheric neutrino and solar neutrino measurement at JUNO can also provide complementary and important information for neutrino oscillation physics. This work focuses on the oscillation physics of JUNO, which includes measurement and analysis of the reactor neutrinos, the atmospheric neutrinos, and the solar neutrinos. With the delicate energy response calibration and event reconstruction potential, JUNO will make a world-leading measurement on the neutrino oscillation parameters and neutrino mass ordering in the near future.

Development of an Integrated C-Arm Interventional Imaging System With a Strip Photon Counting Detector and a Flat Panel Detector.

Modern interventional x-ray systems are often equipped with flat-panel detector-based cone-beam CT (FPD-CBCT) to provide tomographic, volumetric, and high spatial resolution imaging of interventional devices, iodinated vessels, and other objects. The purpose of this work was to bring an interchangeable strip photon-counting detector (PCD) to C-arm systems to supplement (instead of retiring) the existing FPD-CBCT with a high quality, spectral, and affordable PCD-CT imaging option. With minimal modification to the existing C-arm, a 51×0.6 cm2 PCD with a 0.75 mm CdTe layer, two energy thresholds, and 0.1 mm pixels was integrated with a Siemens Artis Zee interventional imaging system. The PCD can be translated in and out of the field-of-view to allow the system to switch between FPD and PCD-CT imaging modes. A dedicated phantom and a new algorithm were developed to calibrate the projection geometry of the narrow-beam PCD-CT system and correct the gantry wobbling-induced geometric distortion artifacts. In addition, a detector response calibration procedure was performed for each PCD pixel using materials with known radiological pathlengths to address concentric artifacts in PCD-CT images. Both phantom and human cadaver experiments were performed at a high gantry rotation speed and clinically relevant radiation dose level to evaluate the spectral and non-spectral imaging performance of the prototype system. Results show that the PCD-CT system has excellent image quality with negligible artifacts after the proposed corrections. Compared with FPD-CBCT images acquired at the same dose level, PCD-CT images demonstrated a 53% reduction in noise variance and additional quantitative imaging capability.

Identifying Internal Stresses during Mechanophore Activation

Mechanophores (MPs) undergo chemical reactions to become fluorescent in response to a mechanical stimulus that reflects the magnitude and distribution of applied stress. MPs are an emerging technology for self‐reporting damage sensing applications in polymeric materials in the aeronautical, energy generation, and automotive industries. However, quantitative calibration of the MP response to local stresses remains an outstanding challenge. Herein, a method to calibrate the intensity of the MP fluorescent activation (I) with local hydrostatic stresses (σh) is presented. Uniaxial tension is applied to a simple composite comprised of a rigid sphere (silica) embedded in a MP‐functionalized elastomeric matrix (spiropyran (SPN) functionalized polydimethylsiloxane (PDMS)). By monitoring the fluorescence intensity with a confocal microscope while a quasi‐static deformation is applied, in situ observations of MP activation as a function of applied uniaxial strain are obtained. To calculate the associated stress fields, a finite element analysis (FEA) with cohesive zone elements is employed. By comparing σh, calculated through FEA with the I of the PDMS/SPN system, a linear relationship between I and σh is directly determined. The technique presented can be employed for many MP‐containing materials systems to calibrate I to σh.

Development of electrical substitution Fourier transform spectrometry for absolute optical power measurements.

We have demonstrated the first continuous-scan electrical substitution Fourier transform spectrometer (ES-FTS), which serves initially as an apparatus for absolute spectral responsivity calibrations of detectors over the wavelength range from 1.5 µm to 11 µm. We present data on the realization of a spectral detector-comparator system with high accuracy, high dynamic range, high spectral resolution and fast measurement in the infrared region, which is tied directly to an absolute power scale through electrical substitution. The ES-FTS apparatus employs a commercial Fourier transform spectrometer and a custom electrical substitution bolometer detector to enable spectrally-resolved absolute optical power measurements. A generalization of electrical substitution techniques enables determination of the voltage waveform that must be applied to the bolometer's electrical heater to cancel the optical signal from a Michelson interferometer in order to quantify the time-dependent optical power incident on the bolometer. The noise floor of the electrical substitution bolometer is on the order of 10 pW/Hz½ and its response is expected to be linear from the noise floor to 1 mW. A direct comparison between a pyroelectric standard detector and the ES-FTS has been performed, and experimental results reported here show great potential for this technique.

Timely surveillance and temporal calibration of disease response against human infectious diseases

BackgroundDisease surveillance and response are critical components of epidemic preparedness. The disease response, in most cases, is a set of reactive measures that follow the outcomes of the disease surveillance. Hence, timely surveillance is a prerequisite for an effective response.Methodology/principal findingsWe apply epidemiological soundness criteria in combination with the Latent Influence Point Process and time-to-event models to construct a disease spread network. The network implicitly quantifies the fertility (whether a case leads to secondary cases) and reproduction (number of secondary cases per infectious case) of the cases as well as the size and generations (of the infection chain) of the outbreaks. We test our approach by applying it to historic dengue case data from Australia. Using the data, we empirically confirm that high morbidity relates positively with delay in disease response. Moreover, we identify what constitutes timely surveillance by applying various thresholds of disease response delay to the network and report their impact on case fertility, reproduction, number of generations and ultimately, outbreak size. We observe that enforcing a response delay threshold of 5 days leads to a large average reduction across all parameters (occurrence 87%, reproduction 83%, outbreak size 80% and outbreak generations 47%), whereas extending the threshold to 10 days, in comparison, significantly limits the effectiveness of the response actions. Lastly, we identify the components of the disease surveillance system that can be calibrated to achieve the identified thresholds.ConclusionWe identify practically achievable, timely surveillance thresholds (on temporal scale) that lead to an effective response and identify how they can be satisfied. Our approach can be utilized to provide guidelines on spatially and demographically targeted resource allocation for public awareness campaigns as well as to improve diagnostic abilities and turn-around times for the doctors and laboratories involved.

ICF Linking and Cognitive Interviewing Are Complementary Methods for Optimizing Content Validity of Outcome Measures: An Integrated Methods Review.

Content validity is a fundamental requirement of outcome measures. After reviewing operational needs and existing definitions, content validity we as defined as: the extent to which a measure provides a comprehensive and true assessment of the key relevant elements of a specified construct or attribute across a defined range, clearly and equitably for a stated target audience and context. ICF linkage rules from 2002, 2005, and 2019 have provide increasingly clear processes for describing and evaluating content of outcome measures. ICF Core Sets provide international reference standards of the core constructs of importance for different health conditions. Both are important as reference standards during content validation. To summarize their use as reference standards, the following summary indicators were proposed: (1) Measure to ICF linkage, (2) Measure to (Brief or Comprehensive) Core Set Absolute Linkage, (3) Measure to (Brief or Comprehensive) Core Set Unique Linkage, (4) Core Set Representation, and (5) Core Set Unique Disability Representation. Methods to assess how respondents engage with content are needed to complement ICF-linking. Cognitive interviewing is an ideal method since it used to explore how respondents interpret and calibrate response to individual items on an outcome measure. We proposed a framework for classifying these responses: Clarity/Comprehension, Relevance, Inadequate response definition, Reference Point, Perspective modification, and Calibration Across Items. Our analysis of 24 manuscripts that used ICF linking for content validation since updated linking rules were published found that authors typically used linking to validate existing measures, involved multiple raters, used 2005 linking rules, summarized content at a concept level (e.g., impairment, activity, participation) and/or use core sets as a reference standard. Infrequently, ICF linking was used to create item pools/conceptual frameworks for new measures, applied the full scope of the 2019 linking rules, used summary indicators, or integrated ICF-linking with qualitative methods like cognitive interviews. We conclude that ICF linkage is a powerful tool for content validity during development or validation of PROM. Best practices include use of updated ICF linking rules, triangulation of ICF linking with participant assessments of clarity and relevance preferably obtained using cognitive interview methods, and application of defined summary indicators.