Добірка наукової літератури з теми "Testing-machines Calibration Standards"

This research investigates the possibility of calibrating strain cylinders using laser interferometry, thus providing a new type of transducer that can provide both force and deformation indications. This new method for the calibration of strain cylinders is based on the application of a dual channel laser interferometer in a force standard machine. Using the proposed new method, the relationship between force, deformation, and strain can be calibrated in parallel when calibration forces are applied according to the procedure outlined in ISO 376. Experimental results show that the deformation of a strain cylinder has a definite and stable relationship with the force applied and can be calibrated and directly traced to the wavelength of the laser. Therefore, a new standard that can be used for both alignment verification and indication verification of compression testing machines and other uniaxial testing machines is proven. The research also illustrates the possibility of providing a new deformation-type force transducer using a non-gauged steel cylinder together with a multi-channel laser interferometer.

The accuracy between a dynamic force and a static force applied on a specimen by a fatigue machine is usually not the same. By establishing physical vibration models of fatigue machines, it is concluded that the error of a cyclic force is mainly caused by the inertial force of the vibration mass between the machine sensor and the specimen. After the inertial force is exactly corrected, the force displayed on the machine would be consistent with the real force on the specimen. A standard dynamic force calibration sensor (DFCS) with an inertial force correction method has been used to do calibration of fatigue testing machines in this paper. Compared with the replica test-piece method, the two calibration results are close to each other.

<p class="Abstract">Optical metrology has an increasing impact on observation and experimental activities in Civil Engineering, contributing to the Research and development of innovative, non-invasive techniques applied in testing and inspection of infrastructures and construction materials to ensure safety and quality of life. Advances in specific applications are presented in the paper, highlighting the application cases carried out by LNEC (the Portuguese National Laboratory for Civil Engineering). </p><p class="Abstract">The examples include: (i) structural monitoring of a long-span suspension bridge; (ii) use of close circuit television (CCTV) cameras in drain and sewer inspection; (iii) calibration of a large-scale seismic shaking table with laser interferometry; (iv) destructive mechanical testing of masonry specimens.</p><p class="Abstract">Current and future research work in this field is emphasized in the final section. Examples given are related to the use of Moiré techniques for digital modelling of reduced-scale hydraulic surfaces and to the use of laser interferometry for calibration of strain measurement standard for the geometrical evaluation of concrete testing machines.</p>

The launch of Sentinel-2A and B satellites has boosted the development of many applications that could benefit from the fine resolution of the supplied information, both in time and in space. Crop classification is a necessary task for efficient land management. We evaluated the benefits of combining Landsat-8 and Sentinel-2A information for irrigated crop classification. We also assessed the robustness and efficiency of 22 nonparametric classification algorithms for classifying irrigated crops in a semiarid region in the southeast of Spain. A parcel-based approach was proposed calculating the mean normalized difference vegetation index (NDVI) of each plot and the standard deviation to generate a calibration-testing set of data. More than 2000 visited plots for 12 different crops along the study site were utilized as ground truth. Ensemble classifiers were the most robust algorithms but not the most efficient because of their low prediction rate. Nearest neighbor methods and support vector machines have the best balance between robustness and efficiency as methods for classification. Although the F1 score is close to 90%, some misclassifications were found for spring crops (e.g., barley, wheat and peas). However, crops with quite similar cycles could be differentiated, such as purple garlic and white garlic, showing the powerfulness of the developed tool.

Background: In recent years, genetically modified technology has developed rapidly, and the potential impact of genetically modified foods on human health and the ecological environment has received increasing attention. The currently used methods for testing genetically modified foods are cumbersome, time-consuming, and expensive. This paper proposed a more efficient and convenient detection method. Methods: Near-infrared diffuse reflectance spectroscopy (NIRDRS) combined with multivariate calibration methods, including principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and support vector machines (SVM), were used for identification of different rice varieties and transgenic (Bt63)/non-transgenic rice. Spectral pretreatment methods, including Norris–Williams smooth (NWS), standard normal variate (SNV), multiplicative scatter correction (MSC), and Savitzky–Golay 1st derivative (SG 1st-Der), were used for spectral noise reduction and effective information enhancement. Accuracy was used to evaluate the qualitative discriminant models. Results: The results showed that the SG 1st-Der pretreatment method, combined with the SVM, provided the optimal model to distinguish different rice varieties. The accuracy of the optimal model was 98.33%. For the discrimination model of transgenic/non-transgenic rice, the SNV-SVM model, MSC-SVM model, and SG 1st-Der-PLS-DA model all achieved good analysis results with the accuracy of 100%. Conclusion: The results showed that portable NIR spectroscopy combined with chemometrics methods could be used to identify rice varieties and transgenic characteristics (Bt63) due to its fast, non-destructive, and accurate advantages.

Uncertainty estimation is one of the very delicate tasks in the field of measurements. For the purpose of calibration of Charpy impact testing machines, it is necessary to evaluate and identify the expanded uncertainty. Factors affecting the uncertainty estimations are; the uncertainty of reference force and length measuring devices and its long-term instability (drift), machine resolution, rated energy error, indicated energy error, losses due to the drag of the pointer, friction losses in the bearing and air resistance, and other geometric parameters. In this study, the uncertainty estimation of the Charpy impact machines is based on the direct verification used in the BS DIN ISO 148-2 standard.

Abstract Background Widespread elimination of malaria requires an ultra-sensitive detection method that can detect low parasitaemia levels seen in asymptomatic carriers who act as reservoirs for further transmission of the disease, but is inexpensive and easy to deploy in the field in low income settings. It was hypothesized that a new method of malaria detection based on infrared spectroscopy, shown in the laboratory to have similar sensitivity to PCR based detection, could prove effective in detecting malaria in a field setting using cheap portable units with data management systems allowing them to be used by users inexpert in spectroscopy. This study was designed to determine whether the methodology developed in the laboratory could be translated to the field to diagnose the presence of Plasmodium in the blood of patients presenting at hospital with symptoms of malaria, as a precursor to trials testing the sensitivity of to detect asymptomatic carriers. Methods The field study tested 318 patients presenting with suspected malaria at four regional clinics in Thailand. Two portable infrared spectrometers were employed, operated from a laptop computer or a mobile telephone with in-built software that guided the user through the simple measurement steps. Diagnostic modelling and validation testing using linear and machine learning approaches was performed against the gold standard qPCR. Sample spectra from 318 patients were used for building calibration models (112 positive and 110 negative samples according to PCR testing) and independent validation testing (39 positive and 57 negatives samples by PCR). Results The machine learning classification (support vector machines; SVM) performed with 92% sensitivity (3 false negatives) and 97% specificity (2 false positives). The Area Under the Receiver Operation Curve (AUROC) for the SVM classification was 0.98. These results may be better than as stated as one of the spectroscopy false positives was infected by a Plasmodium species other than Plasmodium falciparum or Plasmodium vivax, not detected by the PCR primers employed. Conclusions In conclusion, it was demonstrated that ATR-FTIR spectroscopy could be used as an efficient and reliable malaria diagnostic tool and has the potential to be developed for use at point of care under tropical field conditions with spectra able to be analysed via a Cloud-based system, and the diagnostic results returned to the user’s mobile telephone or computer. The combination of accessibility to mass screening, high sensitivity and selectivity, low logistics requirements and portability, makes this new approach a potentially outstanding tool in the context of malaria elimination programmes. The next step in the experimental programme now underway is to reduce the sample requirements to fingerprick volumes.

There are several labs operating throughout the world, which does not follow a designated guideline for calculating measurement uncertainty for force calibrations done in accordance with the ASTM E74 standard. Realizing the need for a guidance document, Morehouse decided to draft this document explaining how to calculate measurement uncertainty and how uncertainty propagation for force calibration systems works. The document examines uncertainty contributors for different tiers in the calibration hierarchy. We start with tier one laboratories using primary standards which are dead weight machines and work through the uncertainty propagation through tier two or secondary laboratories and then tier three laboratories. Calibrations, repeatability studies, and other tests were performed at each tier using different types of force calibration equipment. The paper follows the uncertainty progression and answers a question of what type of calibration standard and Calibration and Measurement Capability (CMC) is needed to achieve a specific Calibration and Measurement Capability at the next tier. Through examining the various uncertainty contributors we arrive at a conclusion that several force scopes may not be realistic in their CMC claims which means they may not be able to make statements of conformance. The testing proved the importance of the reference standard in relation to overall expanded uncertainty. Deadweight primary standards are predictably the best possible reference standard. A laboratory using secondary standards—those standards calibrated by deadweight—can achieve CMC’s as low as 0.02 % of applied force if they are using several standards. Nonetheless, the downside of using several standards is that this method involves standards to be changed at least once during the calibration which often further impacts test results. Failing to account for all the uncertainty contributors at any tier and not calculating Calibration and Measurement Capability properly will influence the Unit Under Test (UUT) in several ways resulting in lower combined uncertainties and raising measurement risk levels on all instruments in the entire measurement chain.

Solving issues in testing articulated arm coordinate measuring machines by bringing homogeneity to the process was the intention of the standard but it also had the consequence of being difficult to comply with in 100% totality. Accessibility to appropriate testing standards, whether financially or in their inherent stability can prove very difficult for a commercial calibration laboratory. Through hours of design & build and with deep testing resources, Trescal has created a platform from which AACMM with effective diameters up to 10.5 ft can be tested for touch measurement, and ISO17025 accredited, with full compliance to the B89 standard.

A coordinate measuring machine (CMM) is a measuring system, with the means to move a probe system, to determine spatial coordinates on a work piece surface. It is a 3-dimensional measuring device for determining the physical geometrical characteristics of objects. To verify the performance of a CMM, it is essential to carry out acceptance tests and with subsequent periodic checks to it in accordance with ISO 10360-2, which is an international geometrical product specification standard for CMM testing. At Standards and Calibration Laboratory (SCL), a calibration method, meeting the requirements of the latest edition of ISO 10360-2, is developed using precision step gauges as the reference standards to calibrate CMMs with measurement results traceable to the unit of length (i.e. the metre). Method for estimation of measurement uncertainty is also developed in accordance with the JCGM 100:2008 (Guide to the Expression of Uncertainty in Measurement), ISO/TS 15530-1:2011 and ISO/TS 15530-3:2011 (Guidelines for the Evaluation of CMM Test Uncertainty).Learning Objectives: To develop methods for CMM calibration meeting ISO 10360-2:2009 and uncertainty evaluation in accordance with JCGM 100:2008.