Calibration Certificate Research Articles

THE USE OF MATHEMATICAL MODELLING TO ESTABLISH THE INTERCALIBRATION INTERVAL OF MEASURING LABORATORY INSTRUMENTS OF GRAIN LABORATORIES

Calibration of measuring instruments is a critical aspect of ensuring the accuracy, reliability, and standardization of quality and safety assessments in grain laboratories. Precise measurements are essential for evaluating key agricultural product parameters, including moisture content, protein concentration, and contaminant levels, which directly influence market value, food safety, and regulatory compliance. Regular calibration of laboratory equipment is mandated by ISO/IEC 17025:2017, which establishes general requirements for the competence of testing and calibration laboratories. This standard ensures measurement traceability, harmonization with international benchmarks, and reproducibility of analytical results. However, frequent calibration procedures present a significant financial burden for laboratories, particularly those operating under budget constraints. The challenge lies in balancing the need for rigorous quality control with cost-effective calibration management. This study explores the optimization of intercalibration intervals by leveraging mathematical modelling, specifically the application of control charts and statistical regression techniques. The research analyzes calibration data from two categories of instruments: simple measuring devices, represented by glass hygrometers (229 calibration certificates), and complex precision equipment, exemplified by automatic pipettes (79 calibration certificates). A comparative assessment of eight mathematical models, including linear, quadratic, cubic, and exponential regression functions, was conducted to determine the most suitable approach for approximating error progression over time. The findings indicate that while linear regression models provide robust and interpretable predictions for simple instruments, nonlinear models, particularly cubic regression, demonstrated superior predictive accuracy for complex equipment, explaining up to 94–96% of the variance in calibration errors. However, while nonlinear models offer enhanced precision in tracking measurement deviations, they necessitate larger datasets to mitigate the risk of overfitting and erroneous extrapolations. The study underscores the importance of selecting appropriate statistical modelling techniques tailored to the specific characteristics of the instrument being calibrated. By integrating data-driven approaches, laboratories can establish optimal calibration intervals, thereby enhancing measurement reliability while reducing unnecessary calibration costs. The proposed methodology provides a framework for achieving a balance between accuracy, compliance, and economic feasibility in laboratory calibration management.

Consideration of software quality and reusability in the generation of digital calibration certificates

Consideration of software quality and reusability in the generation of digital calibration certificates

Digitalization of basic error and measurement uncertainty of reference meters for electrical energy by utilizing Digital Calibration Certificate (DCC)

Digitalization of basic error and measurement uncertainty of reference meters for electrical energy by utilizing Digital Calibration Certificate (DCC)

Digital Calibration Certificate in a trusted quality infrastructure federated data space: A proof of concept

Digital Calibration Certificate in a trusted quality infrastructure federated data space: A proof of concept

Enhancing the interoperability of calibration certificates

Enhancing the interoperability of calibration certificates

Design and implementation of a digital calibration certificate web service system based on microservice architecture

Design and implementation of a digital calibration certificate web service system based on microservice architecture

DCC2GO – Supporting the implementation of Digital Calibration Certificates in the European metrology community

DCC2GO – Supporting the implementation of Digital Calibration Certificates in the European metrology community

Clinical evaluation of a new device for acceptance testing of Ru-106 plaques in ophthalmic brachytherapy

PurposeOphthalmic brachytherapy treats eye lesions by stitching plaques containing a radionuclide (e.g. Ru-106) onto the sclera. Compliance with quality assurance standards is crucial, but practical limitations complicate independent source strength measurement in clinical practice. In this article, a new prototype for acceptance testing of Ru-106 plaques is assayed to assess its suitability for a hospital's medical physics department. Methods and materialsThe system designed for Ru-106 plaque assessment includes a phantom basin fillable with water, a Si-diode for electrons coupled with an electrometer, type-dependent plaque holders and a micrometre gauge. Testing involved the measurement of three plaque types (CCA, CIB, COB) by six medical physics experts and trainees, the assessment of inter and intra-observer variability and the suitability for measurement at the reference point, 2 mm. ResultsMeasured absorbed dose rates in water at 2 mm from the plaque surface demonstrated compatibility across all testers for the three plaques. Intra and inter-observer variability was minimal (1.0% and 1.3% of the measured value, respectively), confirming system robustness in terms of operator influence. ConclusionsThe system proves suitable for Ru-106 plaque acceptance testing ensuring accurate plaque positioning and dose rate verification at 2 mm. These findings confirm its potential as a support for compliance with quality assurance standards. These results are subject to the issue of the corresponding calibration certificate for the Si-diode.

Operating itself safely: merging the concepts of ‘safe to operate’ and ‘operate safely’ for lethal autonomous weapons systems containing artificial intelligence

ABSTRACT The Ministry of Defence, specifically the Royal Navy, uses the ‘Duty Holder Structure’ to manage how it complies with deviations to maritime laws and health and safety regulations where military necessity requires it. The output statements ensuring compliance are ‘safe to operate’ certification for all platforms and equipment, and the ‘operate safely’ declaration for people who are suitably trained within the organisation. Together this forms the Safety Case. Consider a handgun; the weapon has calibration, design and maintenance certification to prove it is safe to operate, and the soldier is trained to be qualified competent to make predictable judgement calls on how and when to pull the trigger (operate safely). Picture those statements as separate circles drawn on a Venn diagram. As levels of autonomy and complexity are dialled up the two circles converge. Should autonomy increase to the point that the decision to fire be under the control of an Artificial Intelligence within the weapon’s software then the two circles will overlap. This paper details research conclusions within the overlap, and proposes a new methodology able to certify that an AI based autonomous weapons system is “safe to operate itself safely” when in an autonomous state.

Design and Implementation of Digital Calibration Certificate for RFID Tag Storage.

The digital transformation of metrology is one of the most active activities in the field of metrology at present, where the digital calibration certificate (DCC) being developed is the topic receiving the most concern in the current digital transformation. In practical industrial applications, the issue of storage carrier for the DCC plays a crucial role in its promotion and implementation. To address this issue, a DCC meta-model called DCC-Lite schema has been designed along with a corresponding processing method. This solution involves compressing and segmenting the DCC to make it suitable for storage using RFID tags. These RFID tags are affixed to the instruments and accompany them throughout their usage. Additionally, the DCC-RFID processing system has been developed to validate the effectiveness of the DCC meta-model and its corresponding processing method within a wireless temperature acquisition system. Experimental results demonstrate that the system successfully reads and writes the DCC stored within the RFID tag group. Furthermore, it enables automated parsing of the DCC calibration data by the machine and real-time compensation of measurement data to reduce measurement errors.

A view on distributed sound level sensors from the perspective of legal metrology

Paper-based calibration certificates are gradually being replaced by equivalent digital calibration certificates (DCCs). The DCC is human-readable as well as machine-readable which simplifies the administration process significantly. During calibration procedure a measurement instrument is tested on-site in a testing laboratory. However, nowadays sound level sensors are increasingly deployed as distributed systems, where they transmit measurement data from one location (e.g. a workplace in a factory) to a measurement laboratory over available networks. This data transmission process has until now not been considered during calibration procedure or type approval tests. Therefore, requirements for the data transmission process according to the regulations of the European Cooperation in Legal Metrology (WELMEC Guide) must be considered. In this project two digital sound level sensors were selected and tested when deployed as distributed systems. The data collected were used to compare the two systems in accordance with the regulations of the WELMEC guide. In this work the first example of an acoustical DCC is presented and discussed. Further, a list of requirements is proposed that should be considered in the future when developing sound level sensors intended to be used as distributed systems.

Investigation of Digital Calibration Certificate - Digital Test Report Sharing in Metrology Network

With the development of technology, digitalization studies have begun in metrology applications, and digital certificates in accordance with the ISO 17025 standard have started to be produced. There is a need for a platform where digital calibration certificates (DCC) / digital test report (DTR) produced today and to be created in the future are shared. In this study, the topics that digital calibration certificates / digital test report must include according to the ISO 17025 standard are explained, and information is given about the Blockchain structure, which is currently widely used in the financial field. The Blockchain platform suggested for use as a digital calibration certificates / digital test report sharing platform for metrological needs is given in this publication. Suggestions on how to run the process for using Blockchain in digital calibration certificates / digital test report sharing are also given in this study.

Uncertainty Calculation as a Service: Integrating Cloud-Based Microservices for Enhanced Calibration and DCC Generation.

The calibration industry is renowned for its diverse and sophisticated equipment and complex processes, which necessitate innovative solutions to keep pace with rapidly advancing technology. This paper introduces an enhancement to an existing microservice-based cloud architecture, aimed at effectively managing the inherent complexity within this field. The enhanced architecture seamlessly integrates various equipment types and communication technologies, aligning diverse stakeholder expectations into a unified system that ensures efficient and accurate calibration processes. It highlights the integration of microservices to facilitate various methods of uncertainty calculation and the generation of digital calibration certificates (DCCs). A case study on RF power measurement illustrates the practical application and benefits of the enhanced architecture. Although initially focused on RF power measurement, the flexible architecture allows for future expansions to accommodate new standards and measurement techniques. The enhanced system offers a comprehensive approach to managing data flow from calibration equipment to the final generation of DCCs, utilizing cloud-based services for efficient data processing. As a future direction, this extension sets the groundwork for broader applicability across multiple measurement types, ensuring readiness for upcoming advancements in metrology.

Investigations on the beam quality correction factor for ionization chambers in high-energy brachytherapy dosimetry

Objective. To enhance the investigations on MC calculated beam quality correction factors of thimble ionization chambers from high-energy brachytherapy sources and to develop reliable reference conditions in source and detector setups in water. Approach. The response of five different ionization chambers from PTW-Freiburg and Standard Imaging was investigated for irradiation by a high dose rate Ir-192 Flexisource in water. For a setup in a Beamscan water phantom, Monte Carlo simulations were performed to calculate correction factors for the chamber readings. After exact positioning of source and detector the absorbed dose rate at the TG-43 reference point at one centimeter nominal distance from the source was measured using these factors and compared to the specification of the calibration certificate. The Monte Carlo calculations were performed using the restricted cema formalism to gain further insight into the chamber response. Calculations were performed for the sensitive volume of the chambers, determined by the methods currently used in investigations of dosimetry in magnetic fields. Main results. Measured dose rates and values from the calibration certificate agreed within the combined uncertainty (k = 2) for all chambers except for one case in which the full air cavity was simulated. The chambers showed a distinct directional dependence. With the restricted cema formalism calculations it was possible to examine volume averaging and energy dependence of the perturbation factors contributing to the beam quality correction factor also differential in energy. Significance. This work determined beam quality correction factors to measure the absorbed dose rate from a brachytherapy source in terms of absorbed dose to water for a variety of ionization chambers. For the accurate dosimetry of brachytherapy sources with ionization chambers it is advisable to use correction factors based on the sensitive volume of the chambers and to take account for the directional dependence of chamber response.

Design and Implementation of an Ontology for Measurement Terminology in Digital Calibration Certificates.

Digital Calibration Certificates (DCCs) are a key focus in metrology digitalization, necessitating that they satisfy the criteria for machine readability and understandability. Current DCCs are machine-readable, but they are still missing the essential semantic information required for machine understandability. This shortfall is particularly notable in the lack of a dedicated semantic ontology for measurement terminologies. This paper proposes a domain ontology for measurement terminologies named the OMT (Ontology for Measurement Terminology), using a foundation of metrological terms from standards like the International Vocabulary of Metrology (VIM), the Guide to the Expression of Uncertainty in Measurement (GUM), and JJF1001. It also incorporates insights from models such as the SI Reference Point, the Simple Knowledge Organization System (SKOS), and the DCC Schema. The methodology was guided by Stanford's Seven-Step Method, ensuring a systematic development process tailored to the needs of metrological semantics. Through semantic expression capability verification and SPARQL query validations, the OMT has been confirmed to possess essential machine readability and understandability features. It has been successfully integrated into version 3.2.1 of DCCs across ten representative domains. This integration demonstrates an effective method for ensuring that DCCs are machine-readable and capable of interoperating within digital environments, thereby advancing the research in metrology digitization.

Enabling the use of digital calibration certificates in industrial calibration management systems

Abstract. Metrology has been a slowly digitalizing field in which a significant part of the handling of data has been dependent on paper-based processes. Due to the need for the improved efficiency and reliability of these processes, digitalization has become a major topic of interest in the metrology community. Data formats such as the digital calibration certificate (DCC) have an essential role as an enabler of further digitalization, acting as the harmonized data format for calibration data. Naturally, introducing these data formats into industrial usage sets new requirements with respect to the calibration management and associated systems. Diversity of metrology also means that the systems need to be flexible and scalable to fulfill the needs of actors in the global calibration infrastructure with very different requirements. This paper presents a conceptual approach for enhancing the communications between the existing systems in a calibration ecosystem and enabling DCC-based data exchange with third-party systems using the Beamex calibration ecosystem as an example. Thus, the presented system architecture concept that introduces data and DCC exchange services would provide a solution to enable the use of DCCs on Beamex systems.

Web-Based Measuring Instrument Calibration Scheduling Information System

The production method has prioritized guaranteeing excellent manufacturing quality in response to the increasing competitiveness in the clothing industry. Utilizing a fabric roll meter measuring instrument dramatically enhances the overall quality of the product by guaranteeing precise measurements. Roll meter fabric measuring equipment in the garment industry evaluates product accuracy based on customer specifications, ensuring exceptional quality. Effective regulation is essential for the management and upkeep of cloth roll meter measuring instruments. Therefore, it is necessary to develop a system that can evaluate the level of urgency for calibrating various equipment and identify those that need recalibration despite having already been calibrated. This project created a web-based system for scheduling the calibration of fabric roll meters. The system was designed using the PHP programming language and MySQL for database management. Use cases delineate how the user interacts with the system, whereas an activity diagram represents the sequence of user activities. Furthermore, a sequence diagram illustrates the user's participation in chronological order. The information system implements maintenance schedules, oversees the calibration of fabric roll meter measuring instruments, stores calibration certificates, and effectively handles calibration data to guarantee precision and efficiency.

FUNDAMENTAL ASPECTS OF METROLOGICAL SUPPORT IN IoT

The application of intelligent sensors, network technologies, and machine learning in IoT and industry is increas- ingly widespread as a part of the development and implementation of Industry 4.0, Industry 5.0, and Smart City. It is necessary to review the fundamental principles of metrological support for production. This includes calibration, estimation of measurement uncertainty, traceability, and processing of large data sets to reproduce and compare the results of measurements of physical quan- tities remotely. Modern smart sensors are cost-effective, which makes traditional sensor calibration methods increasingly uneco- nomical. The utilization of advanced networking technologies, along with machine learning, complicates the pre-processing of measured values. Therefore, new solutions are required when it comes to implementing digital metrology. In this article, a metrological framework for the full life cycle of measured data in IoT is presented. It ensures transparency, comparability, consistent quality and reliability of measured data, processing methods and results. The OPC-UA digital data com- munication standard is considered, which provides a single interface for exchanging digital data with devices from different manu- facturers or via different protocols. The syntax of a machine-readable representation of SI units and derived quantities as well as the structure of the sensor network metadata model are also described. Special emphasis is placed on dynamic calibration of sen- sors, determining measurement uncertainty in sensor networks, and implementing digital calibration certificates in IoT and industry.

Measuring the enthalpy of combustion of methane gas and establishing the model function to perform comprehensive uncertainty calculations

Natural gas is a plentiful and adaptable energy source among other gases that is used all over the world with an increasing demand nowadays. It is therefore of utmost importance to measure the energy content of the natural gas with high precision for both users and sellers. In this study, methane gas, the main component of natural gas, was combusted using the reference gas calorimeter developed at TUBITAK UME (The Scientific and Technological Research Council of Turkey) - (National Metrology Institute) to determine the enthalpy of combustion. The objective was to measure the enthalpy of combustion of the methane, perform a detailed uncertainty calculation and to compare the enthalpy of combustion of the methane specified in ISO 6976:2016 with the obtained experimental results. The reference gas calorimeter was designed using the temperature, mass, power, flow control, waste water absorption, and waste gas measurement systems with the highest precision and circulating water bath with temperature control insulated so as not to exchange heat from the external environment. All measurements were performed with the instruments having calibration certificates. Experiments were carried out at the temperature of 298.15 K and a constant pressure (101.325 kPa) using the methane with a purity of 99.995 % as a reference gas. The mass of the burnt methane in combustion process was approximately 10-3 kg. As a consequence of the measurements, mean experimental enthalpy of combustion was obtained as −55518.2 kJ kg−1 with the error of 0.2 % (k = 2). The evaluations indicated that the largest source of error in the enthalpy of combustion measurements originated from the temperature and mass measurements.

Main stages of calibration of measuring instruments

The main stages of calibration of measuring instruments are described. The stage of preparation for calibration and its main steps are considered: setting a measurement task, choosing a method and equipment, choosing (developing) calibration methods and their verification (validation). The content of the measurement experiment is presented together with the main measurement methods that can be used to calibrate the indications of measuring instruments and material measures. The main steps of experimental data processing, which lead to the estimation of the numerical value and uncertainty evaluation of the measurand being calibrated, are considered. The preparation of calibration results, including the uncertainty budget and calibration certificate, is described. Procedures for assessing the probability of compliance of a calibrated measuring instrument and material measure with the specified metrological characteristics, as well as for validating their calibration methods, are considered.