MAPAN

This article describes the application of isotope dilution mass spectrometry (IDMS) to the field of reference material (RM) characterisation focusing on the approach, which is applied by the IDMS group at BAM. Emphasis is placed on IDMS measurements of highest analytical quality. Basic principles as well as the equation system are being recalled. Different calibration strategies, such as single, double or triple IDMS, are critically reviewed and the achievable uncertainties are discussed. Differences in the application of thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICPMS) are discussed as well as differences between different types of mass spectrometers such as single collector versus multi-collector or quadrupole versus magnetic sector instruments. Possible sources of errors and bias are mentioned and correction models introduced and applied within the past years are discussed. Several examples for RM characterisations in the field of elemental analysis are shown, each demonstrating excellent analytical quality. In general it can be stated that IDMS is the most important reference method for elemental analysis, offering highest accuracy and precision or smallest measurement uncertainties, when properly applied. Thus IDMS represents by far the best suited reference method for RM characterisation. Due to its universal applicability IDMS offers sufficient potential to follow future needs in analytical chemistry as well as in the RM sector

The paper contains a full derivation of formulas that enable the conversion of current transformer errors measured at unity power factor burden to equivalent errors at 0.8 power factor lagging burden, required by IEC 60044-1, as well as errors at any other burden. The assumptions and limits of the formulas are discussed.

The soluble forms of aluminum are now considered toxic or potentially toxic and they have been associated or related with neurological alterations, liver, bone, hematological disorders and breast cancer. To estimate the expanded uncertainty of a previously validated analytical method to quantify aluminum in tissues of Sprague Dawley rats through flame atomic absorption spectroscopy (FAAS) and electrothermal (ETAAS). The sources of uncertainty through an Ishikawa diagram have been established and the relative and combined standard uncertainty of the concentration of aluminum was determined from the curves of calibration, volumetric material and the dilution factor, repeatability, the purity of a standard aluminium and the concentration of aluminium in two certified reference materials (SRM-S-B and NIST 1566b). The estimates of each source of uncertainty were determined following the Eurachem/Citac Guide. It was possible to estimate the expanded uncertainty (U) with a factor k = 2, and the results were of 3.709 mgL−1 and 3.717 µgL−1 of aluminium in tissues of Sprague Dawley rats with FAAS and ETAAS, respectively. There are few works in which the expanded uncertainty of an analytical method has been found to determine aluminum in tissue, however the results are acceptable and comparable against the results obtained with other methods that estimate the uncertainty of other metals and different matrix or tissue.

The melt flow index (MFI) of commercial polystyrene samples has been investigated throughout an interlaboratory comparison study. The homogeneity samples have been assessed prior to the distribution over the participants. The one-factor analysis of variance model has been applied to separate and evaluate the uncertainty components arising from the analytical method and the heterogeneity of the samples. It has been shown that the samples are sufficiently homogenous. The stability of the samples has been monitored over 6 months. The stability and the uncertainty arising from the instability of the samples have been evaluated throughout the linear regression analysis. No significant trend could be detected over the stability assessment period. The results reported by the participants have been investigated. An almost normal distribution shape has been obtained with no evidence for outlier or systematic bias. The MFI value has been evaluated as consensus value from the results reported by the participants with a standard combined uncertainty of ~ 2.2%.

This paper introduces a novel deadweight force standard machine (DWM) with independent loading weights driving mechanism. So the weights can be individually loaded and unloaded. Because of their free movement, the weights can also be exchanged mutually, and the number of weights can be optimized. In addition, this novel machine requires only a few weights to achieve as much as possible force loading steps, which greatly expands the testing range. This structure and method have been widely used in the production and measurement detection of the DWMs. The loading speed of each step in this 20 kN force standard machine is about 5 s and hence the efficiency is greatly improved. The sensor testing experiments showed that the repeatability accuracies of this device is less than 0.005 %.

Cảm biến áp suất, bộ truyền và bộ chuyển đổi được sử dụng rộng rãi để đo và kiểm soát áp suất. Việc truy xuất số liệu đo của thiết bị cảm biến áp suất là rất quan trọng trong nhiều ứng dụng công nghiệp. Cần phải hiệu chuẩn các thiết bị đo áp suất với độ không chắc chắn chấp nhận được có liên kết với các đơn vị SI. Nghiên cứu này nhằm mục đích nghiên cứu sự lan truyền của độ không chắc chắn từ các đơn vị SI thông qua tổ hợp xilanh pit tông chuẩn chính (PCA) lên đến 500 MPa. Hệ thống phân cấp đo áp suất tại NIS dựa trên việc sử dụng PCA có diện tích hiệu quả lớn trong việc xác định áp suất 1 MPa. Đặc trưng và đánh giá PCA chuẩn chính được trình bày, sau đó là việc chuyển giao kết quả thu được đến các cấp độ truy xuất áp suất khác. Việc tính toán và lan truyền độ không chắc chắn bắt đầu từ chuẩn chính đến các đồng hồ áp suất kỹ thuật số, bộ hiệu chuẩn áp suất kỹ thuật số, cảm biến áp suất và bộ chuyển đổi áp suất đã được nghiên cứu.

Coronavirus disease (COVID-19) has changed the living environment in various aspects just like any other disaster. The goal of this study was to use time series remote sensing data to analyze vegetative cover change in the Western ghats of south India from January 2018 to June 2021 (pre & post covid scenario). In this context, biodiversity in terms of Normalized Differential Vegetation Index (NDVI) has been investigated in relation to variations in anthropogenic activity levels before and after the Covid-19 period. A spatio-temporal analysis of NDVI, LULC change, rainfall and AOD in relation to lockdown due to Covid-19 was conducted in this study. The study demonstrates the adaptability of remote sensing techniques and GIS for monitoring the changes in biodiversity in a more precise and cost-effective way, which is ideal for conservation planning and prioritization. Also, this study investigates the relationship between rainfall, AOD and NDVI during the study period. The results show that some parts of the Western Ghats which lies in Chamrajnagar of Karnataka, Erode and Dharmapuri of Tamil Nadu experienced significant vegetative cover change during the study period. It is also been inferred that there are changes in vegetative cover along the transect points situated in Shimoga of Karnataka, Palakkad and Idukki of Kerala due to the outbreak of forest fires. The restriction during the Covid-19 lock down has minimized the disturbance in the Ghats region which echoed in the increase in vegetative cover as well as areal extent of water bodies during post corona period (2021). The effect of increase in rainfall has reflected in the reduction in concentration of aerosol due to wet scavenging effect.

This work regarding the design and development of EN 24-grade steel-based force transducer has been reported along with its metrological features in line with ISO 376:2011 standard. The force transducer has been designed on the basis of analytical and computational methodology and validated through experimental observations. The force transducer presents ease of design-cum-manufacturing and practically viable alternative to the commercial force transducers with uncertainty of measurement up to 0.10% in its working range.