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Liyue Yan, Houjun Wang, Hao Wang, Zhen Liu
A B-spline and OS-ELM Fusion Approach for Prognostics with Singularity Problems

In practice, the degradation process of electronic products is usually accompanied with singularities caused by intermittent and transient interference, improper conduct on singularity processing would inevitably and seriously affect the accuracy of products’ life-time prediction. Taking advantage of rapid development of AI technology recent year, a new surrogate approach based on spline function and online sequential extreme learning machine (OS-ELM) is developed in this paper, to address these issue. This fusion approach takes the cubic non - polynomial spline function as the prediction cell of the output from OS-ELM, the second derivative of the spline model can be adopted and calculated to form a series of observation frames, meanwhile, an improved particle swarm optimization (PSO) is used to optimize the parameters of ELM hidden network to help with forecasting the observation sequence and rebuild the spline function. In the verification stage, two numerical simulation examples and a practical application involving typical time series data with singularities demonstrate the effectiveness of this proposed fusion method, respectively.

Mohamad Syahadi, Hayati Amalia, Agah Faisal
Implementation of BIPM Calibration Values to Calibration of A Solid State DC Voltage Standard in Laboratory of National Measurement Standard for Electricity and Time – BSN (SNSU – BSN)

A method for calibrating a solid state DC voltage standard in Laboratory of National Measurement Standards for Electricity and Time (NMS ET Lab) of National Standardization Agency of Indonesia is presented in this paper. The measurement and its evaluation are carried out based on differential measurement method to the test of solid state DC voltage standard by implementing calibration values from Bureau International des Poids et Mesures (BIPM) at the nominals of 1.018 V and 10 V. Corrections due to temperature, pressure, humidity coeficient and drift are also examined. Based on evaluation result, actual values for the 1.018 V and 10 V of the test were found to be 1.0179897 V and 9.999857 V with their respective measurement uncertainties of 1 μV and 17 μV.

Phuritpach Nantasitangkool, Nitiphat Kittirakshakula, Wanna Watcharayotinkul, Worapot Prongmanee, Umaporn Lamdab, Siripassorn Sukhkhawuttigit, Hathaichanok Muenkla, Nalin Ratnarathorn, Rung Kumpoo, Nakarin Sihabunmak, Zenith Samransamruadkit
Interlaboratory Comparison of Gunshot Residue Analysis

The investigation of Gunshot Residue (GSR) in Forensic science was carried out by Scanning Electron Microscope (SEM) energy-dispersive x-ray spectroscopy (EDS) and Inductively Coupled Plasma - Optical Emission Spectrometer (ICP-OES). These techniques are not widely used in Thailand. However, the commercial laboratory (CL), Central Institute of Forensic Science (CIFS), and the Royal Thai Police (RTP) attempt to develop these techniques to promote novel ways for GSR analysis. Also, the standard measurement was a crucial requirement in ISO/IEC 17025 quality standard. As a part of quality assurance, proficiency testing and interlaboratory measurement are important criteria in technical requirements. Therefore, the preliminary design of GSR analysis for interlaboratory in Thailand was developed. The quality control sample (QC-sample) was prepared by collecting GSR from the right-hand’s volunteer after shooting. The comparison of GSR analysis between the commercial laboratory and Royal Thai Police for SEM technique and between Central Institute of Forensic Science (CIFS) and the Royal Thai Police for ICP-OES technique. This research was then compared by a paired t-test at the 95 % confidence level. The results indicated the efficiency to detect GSR under the same condition between the commercial laboratory and Royal Thai Police and Central Institute of Forensic Science (CIFS) and the Royal Thai Police are similar.

Muhammad Azzumar, Lukluk Khairiyati, Nibras Fitrah Yayienda, Mohamad Syahadi, Hayati Amalia, Hadi Sardjono, Miftahul Munir, Agah Faisal, Windi P. Kurnia , Ashri C. Khusnul
An Early Development of Software for Automatic Measurement of Multifunction Calibrator

This paper describes an early development of software for automatic measurement of the multifunction calibrator using direct measurement method with the reference multimeter. The software is developed to control the multifunction calibrator and the reference multimeter using GPIB interface. The developed software can do single point measurement and multi points measurement by configuring the instruments automatically. For the security reasons against the instruments, it is equipped with a pop-up alert to indicate that a connection change is required before the measurement begin, because the multifunction calibrator commonly has three electrical measuring quantities (voltage, current, and resistance) that have different connection for each of the quantity. The measurements can be made with some repeatability to reduce the type A uncertainty and the measurement results then tabulated as raw data. The results can be saved as a certificate of calibration automatically from the template in which the correction and the expanded uncertainty are calculated. Therefore, the accurate and precision measurements for calibrating and testing the electrical equipment can be performed with easy, safe and fast.

Andrés J Bohórquez, Sergio A. Carvajal, Ciro A. Sánchez, Astrid Riveros
Long-Term Loading Effect on Stability and Spatial Uniformity of Climatic Chambers

In this work, a study of the impact that the commonly-known ‘loading effect’ has over the determination of inhomogeneity and temporal stability of a climatic chamber is presented. Consecutive yearly characterizations of a twopressure humidity generator treated as a climatic chamber revealed that the spatial inhomogeneity strongly depends on the environmental conditions of the laboratory as well as the percentage of the work volume occupied by ‘loading devices’, such as capacitive thermohygrometers. Results show that temperature and relative humidity measurements can vary as much as 0.4 °C and 0.1 %HR, respectively, if the load occupies at least 40% of the work volume. The effect on stability is considerably lower and in the worst case is 0.01 °C and 0.06 %HR.

Carlos España, Gustavo Gómez, Katherin Holguín, Johanna Abella, Diego A. Ahumada
Proficiency testing schemes for Cadmium in cocoa powder analysis for Colombian laboratories

This paper shows the experience in the operation of a proficiency test for the analysis of Cadmium in Cocoa. Due to the limited number of analytical laboratories participating, this proficiency test was developed with two reference materials (RMs), which were prepared from cocoa beans. The certified value for Cadmium in the two RMs (low and high concentration levels of Cadmium) was based on the agreement of results of at least two methods: ICP-MS and GF-AAS conducted at the National Metrology Institute of Colombia. The homogeneity and stability studies were performed according to guide ISO 35. In the first study, it was found an uncertainty associated to homogeneity between bottles of 0.06 % for low concentration level and 0.89 % for the high concentration level. Stability contribution was estimated by 0.24 % in accelerated conditions and 0.47 % in the long-term conditions. On the other hand, the assigned value was 0.202 ± 0.018 mg/kg by low concentration of the RM and 2.32 ± 0.15 mg/kg by the second one. The proficiency testing scheme counted with the participation of 10 laboratories with unsatisfactory results only for one participant. Following this scheme, some tools for improvement were identified such as the use of both internal and subrogate quality control standards for measurement, among others.

Johanna Abella, Andrea Mojica, Diego A. Ahumada
Assessment of the homogeneity of repackaged batches of reference materials

During 2020, the National Metrology Institute of Colombia, organized one proficiency testing (PT) for the quantification of elements in water. In the PT, external reference values were used instead of consensus values derived from the participants' results. The test material used in the PT was a certified reference material from another National Metrology Institute. To maintain the confidentiality of certified values, it was necessary to carry out a repackaging process. Therefore, in this work are presented the results of several studies that sought to establish the best mechanism to carry out this repackaging process. Among the investigations carried out, were evaluated: (i) kind of sampling and (ii) the number of bottles to assess the homogeneity of the new batch. The homogeneity uncertainty was estimated based on the number of bottles and depending on the type of sampling. From the results, it was identified that (i) most of the elements evaluated, the smallest contribution to the uncertainty is obtained when every two units are systematically sampled, and (ii) the estimation of uncertainty due to homogeneity causes an overestimation up to three times when the number of bottles is varied.

Laura E. Morales, Diana C. Sinuco, Diego A. Ahumada
Stabilization strategies for unstable pesticides in calibration reference materials

To achieve measuring methods harmonization, improve reliability, and quality of measurement results, the use of certified reference materials (CRM) are necessary. Due to the instability of some compounds, the offer of CRM of pesticides is low. The National Metrology Institute of Colombia, as reference materials producer, has evaluated strategies to determinate and improve the stability of ten multiclass selected pesticides in calibration solutions. For this purpose, to obtain an overview of the degradation behavior of pesticides, ten compounds with different physicochemical characteristics were chosen. Three mixtures were prepared, which contained one polychlorinated biphenyl (PCB) as control. Various strategies were applied for the stabilization of the pesticides (an additive, inert atmosphere, and their combinations). The stability assessment was performed using an isochronous design at extreme conditions to induce a faster degradation of the compounds. Three analytical methods using gas chromatography were developed and validated. After methods validation, the stability measures were realized under repeatability conditions. The results were evaluated using regression. The results demonstrated that the strategies used for stability increasing were adequate for all of the evaluated compounds. In this study, it was found that when a stability strategy is adopted, the uncertainty associated with the stability improve up to 15 times.

Leonardo Soto, Niño Fabian, Diego A. Garzón, Diego A. Ahumada
Development of Reference Material of Mercury in Fish: A comparison of different alternatives to homogeneity assessment

A candidate to certified reference material for mercury in fish was produced from Calophysus macropterous, a species of catfish that has been reported with high levels of this contaminant at the Amazonian region. The fish was filleted, freeze-dried and degreased, then sieved, homogenized and packaged; 106 bottles were produced with a net content of 15 g. In the study of homogeneity of the material, ICP-MS in standard mode was used, like a measurement method with microwave-assisted acid digestion. The homogeneity assessment with a random sampling stratified was carried out. The preparation and measurements of the samples were carried out using microwave-assisted digestion and ICP-MS. The current study involved the evaluation of different isotopes (199Hg, 200Hg, 201Hg, 202Hg) and internal standards to correct the analytical signals. Finally, to evaluate the uncertainty due to heterogeneity, different approaches were used. The results showed that there are differences between the classic ANOVA approach and meta-analysis methods, especially when MSbetween < MSwithin. Furthermore, the most important differences were found between the uncertainties using different combinations of isotopes / internal standards, because in some cases, up to three times higher uncertainties were found.

Antonella Gaspari, Giulio D’Emilia
A Maintenance Assessment Measurement-Based Method For SMEs: Case Study of an Italian Mechanical Reality

The Industry 4.0 enabling technologies offer new opportunities of innovation for many Small and Medium Enterprises (SMEs). More and more, the information deriving from measurements by intelligent and advanced data processing gives possibility of introducing new and smart approaches in many sectors contemporaneously, like production, maintenance, energy saving and supply chain management. Validation of data to be used for this multi-purpose analysis is mandatory, starting from the very preliminary phase. Taking in mind typical operating scenarios of Italian SMEs, in this paper a set of guidelines and requirements are given, in order to take advantage of the data-driven technical solutions for smart maintenance, providing that measurement data are reliable. The most important aspects to be considered for a more reliable analysis are presented, with reference to predictive maintenance projects carried on a complex plant and a specific sub-system. Simple considerations are shown to be able to avoid heavy mistakes.

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