Calibration Capabilities Research Articles

Volume Measurement of Large Volumetric Vessel Using Tap Water

Being a National Metrology Institute (NMI) of India, CSIR-National Physical Laboratory, India (NPLI), provides calibration services to the industries to improve the quality of products. In the last couple of years, NPLI has provided number of calibration services of volumetric vessels up to 2000 L (unique facility in India) to the petroleum industries, flow meter manufacturing industries, etc. In general, for the calibration of volumetric instruments, distilled water is used as the medium but in the case of large volumetric vessels (say 2000 L), the use of distilled water is not practical. Hence, tap water is used and every time the density of tap water is measured against distilled water to improve the accuracy of the measurement. In this process, we have achieved measurement uncertainty less than 50 mL in 2000 L. But due to influencing factors of environmental conditions of laboratory, change of density of supplied tap water, conversion factors of tap water and distilled water in desire temperature, we have restricted our calibration and measurement capability (CMC) up to 100 mL in 2000 L. In this paper, we have discussed the detailed procedure of volume measurement of 2000-L volumetric vessel and its associated uncertainty calculations using gravimetric method.

Uncertainty evaluation and phase variation of ultrasonic interferometer manometer: A primary pressure and vacuum standard

The ultrasonic interferometer manometer (UIM) is an apex level primary pressure standard for Pascal realization established at National Physical Laboratory India (NPLI). The performance of UIM has been evaluated from time to time by participation in key comparisons, calibration and measurement capabilities (CMC) and publications in reputed international metrology journals. The pressure is measured using time of flight technique at 44 different frequencies in ultrasonic range and the phase measurement. The phase measurement combined with the time of flight measurement using the exact fractional algorithm provides highly accurate column length hence respective pressure values. The combined process helps in lowering the uncertainty in real experimental conditions. Recently, we have also changed UIM software from tbasic to window based program with the same algorithm which provides a column length measurement study. A detailed study was carried out for variation of fringe counts or oscillations with varying pressure. Experimental and theoretical calculation for both resolution and pressure dependent part has been carried out for uncertainties involves the physical parameters. The uncertainties in lower pressure range, i.e., between 1 Pa and 1000 Pa were varying equal or sometimes higher than the theoretical resolution value 0.0092 Pa (k = 2) because of environmental conditions like vibration, temperature, atmospheric pressure, and humidity whereas for higher pressure range, i.e., 1000 Pa to 130 kPa the uncertainties were either close or smaller than the pressure dependent theoretical uncertainty value, i.e. 7.2 × 10−6 of the reading.

Calibration of random fields by FFTMA-SA

A new algorithm is presented aiming to generate realizations calibrated to desired or observed field response functions. The Fast Fourier Transform Moving Average - simulated annealing algorithm (FFTMA-SA) combines the FFTMA method of simulation and the simulated annealing (SA) method for calibration. SA is performed on the uncorrelated random numbers used within the FFTMA algorithm, keeping by construction the field covariance function unchanged. Hard data exact conditioning by kriging is easily introduced into the algorithm main loop. An interesting advantage of FFTMA-SA is the capability to perturb the field locally or globally, simultaneously on any desired number of points. We therefore introduce a decreasing schedule on the number of points to perturb mimicking the cooling schedule of the temperature parameter in SA. Two cases studies are presented. The first one is a spatially asymmetric synthetic field where FFTMA-SA is shown to better reproduce the spatial asymmetry than calibrated realizations obtained either by classical SA or by FFTMA combined with gradual deformation. The second example is the Walker Lake data where regularized row and columns facies proportions are imposed. It is shown that few iterations (100) of FFTMA-SA are enough to reproduce the main characteristics of the proportion curves. Increasing the number of iterations only reduces rather uniformly the variability of realization proportions. The same data is used to illustrate the local calibration capability of the method with a local data assimilation example. The proposed algorithm offers a simple and flexible tool for calibration. It is easily adaptable for any moving average method of simulation.

The effect of cues for calibration on learners' self-regulated learning through changes in learners’ learning behaviour and outcomes

Literature on blended learning emphasizes the importance of self-regulation for learning in blended learning environments and the role of learners' calibration. Although literature on calibration is clear on its importance for self-regulated learning, it provides inconclusive insight into the effect of support for calibration on learners' self-regulated learning. One under-investigated avenue might be learners' ability to act on the cues provided. In order to establish a more accurate picture of the effect of support for calibration on self-regulated learning, our study investigates whether providing cues for calibration affects learners' self-regulated learning, and whether this effect is different for learners with different metacognitive abilities. We investigate this effect by examining changes in learners' learning behaviour and outcomes. A pre-post design with one control and two experimental conditions was applied in a blended learning environment. Learners in the experimental conditions received either functional validity feedback (F condition) or functional and cognitive validity feedback (FC condition). Learners in the control condition did not receive any cues. Learners' behaviour was analysed using event sequence analysis. Learners' post-test learning scores were subjected to multivariate analysis of covariance, with condition and learners' metacognitive ability as independent variables. The results show a significant and unexpected impact of condition and learners' metacognitive abilities on learners' learning behaviour and outcomes. This manuscript discusses the unexpected results in terms of their theoretical and practical implications and provides recommendations for future research. We conclude that if cues for calibration are provided through functional and cognitive validity feedback, learners’ calibration capabilities will increase. Yet, we hypothesize that for this to result in goal-directed self-regulated learning, learners might need to be guided in how to apply the cognitive and metacognitive strategies needed.

Improving the measurement standard for the metrological support of the porometry of solid substances and materials

The State Primary Measurement Standard for units of specific gas adsorption, specific surface area, specific volume and pore size of solid substances and materials (GET 210–2014) is currently in operation at UNIIM. The GET 210-2014 has calibration and measurement capabilities for pore size in a range from 2 to 100 nm, while in practice there is a need to control the pore size of solid substances and materials in a range from 100 to 10,000 nm. In order to enhance the calibration and measurement capabilities of the GET 210-2014, it was proposed to include two reference systems implementing the methods of mercury porometry and stationary filtration into the measurement standard. This work considers the state of the metrology of porometry and presents the first results of studies on the metrological characteristics of reference systems implementing the methods of mercury porometry and stationary filtration. Algorithms for calculating the uncertainty of quantities being reproduced via the methods of mercury porometry and stationary filtration and characterizing the porosity of solids have been developed and tested. The reliability of the developed algorithms is confirmed by: the results of participation in 4 international comparisons, the measurements of foreign-made reference materials, along with the results of participation in 6 rounds of interlaboratory comparisons. The measurement standard improvement will provide metrological support to measuring instruments and measurement procedures for sorption properties, porosity and gas permeability of solid substances and materials in various industrial sectors. Thus, the metrological independence of the Russian Federation will be ensured and import substitution of expensive foreign reference materials carried out.

Participation of VNIIFTRI in international comparisons in thefield of physical-chemical measurements

This paper considers the participation of FSUE «VNIIFTRI» in international comparisons: in the field of physicalchemical measurements, particularly in pH-metry and ionometry (pX); in the sphere of measuring inorganic components in various matrices. Measurement and calibration capabilities are presented – CMC lines in the BIPM database.

A Defect-Tolerant Reusable Network of DACs for Wafer-Scale Integration

A novel defect-tolerant network of digital-to-analog converters (DACs) is presented in this paper. The architecture of this converter employs a single 2.5-V voltage reference and an unbalanced buffering technique to achieve a wide voltage range that extends from 864 mV to 2.538 V with an 8-bit resolution. The proposed converter incorporates a defect-tolerant architecture and is extremely compact, utilizing a per-bit silicon area of less than 350 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Although such very small area allows for embedding in dense configurable fabrics (field-programmable gate arrays) and wafer-scale integration, the overall performance is not sacrificed as reported measurements show a signal-tonoise ratio of 51.87 dB and a spurious-free dynamic range of 42.31 dB, at 10 MS/s providing 7.6 effective bits. Moreover, the proposed architecture benefits from dynamic calibration capabilities, as any converter output can be finely adjusted over a range of 25 mV. This proposed DAC is also extensively reused in the same defect-tolerant network for a successive approximation register-analog-to-digital converter, as well as for a configurable voltage reference.

PC-VINS-Mono: A Robust Mono Visual-Inertial Odometry with Photometric Calibration

&lt;p&gt;Feature detection and Tracking, which heavily rely on the gray value information of images, is a very importance procedure for Visual-Inertial Odometry (VIO) and the tracking results significantly affect the accuracy of the estimation results and the robustness of VIO. In high contrast lighting condition environment, images captured by auto exposure camera shows frequently change with its exposure time. As a result, the gray value of the same feature in the image show vary from frame to frame, which poses large challenge to the feature detection and tracking procedure. Moreover, this problem further been aggravated by the nonlinear camera response function and lens attenuation. However, very few VIO methods take full advantage of photometric camera calibration and discuss the influence of photometric calibration to the VIO. In this paper, we proposed a robust monocular visual-inertial odometry, PC-VINS-Mono, which can be understood as an extension of the opens-source VIO pipeline, VINS-Mono, with the capability of photometric calibration. We evaluate the proposed algorithm with the public dataset. Experimental results show that, with photometric calibration, our algorithm achieves better performance comparing to the VINS-Mono.�&lt;/p&gt;

Comparison of length standards in the range of 0.001 to 1 mm

The COOMET Project No 569/UA/12 "Comparison of length standards in the range of 0.001 to 1 mm", KCDB Reference COOMET.L-S14, was organized by TC 1.5 "Length and Angle" of COOMET. This comparison started in July 2015 and finished in August 2016. It was piloted by the National Scientific Center "Institute of Metrology", Kharkov, Ukraine with other participants as follows VNIIM (Russia), SKS RSE KazInMetr (Kazakhstan).This supplementary comparison is carried out with the purpose of confirming calibration and measurement capabilities of the corresponding national metrology institutes of Ukraine, Russia and Kazakhstan.Standard measuring instruments are taking part in comparison with the aim of providing validity of linear dimensions of measurements, of CMCs in the field of measurements of length.The reference line gauge of comparison with a length of 1 mm scale is measured in the NSC "Institute of Metrology", thereafter it is successively delivered to all participants of comparison. After the measurement by the last participant, the reference line gauge is measured at the NSC "Institute of Metrology" for checking its stability.By the end of comparison, the reference line gauge is not used for any other purposes except comparisons.According to the results of the analysis provided by all participants of the data comparisons, the value of criterion χ2 does not exceed the critical value (χ2 0.95 = 5.99) for all measured intervals of the comparison measure, that is the objective confirmation of the announced uncertainties.The comparison results help to support the calibration and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA.KEY WORDS FOR SEARCHreference line, interval length, deviationMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of industrial platinum resistance thermometers in thermostats (-40 °C to 420 °C)

The COOMET.T-S2 comparison is a regional comparison in which the national metrological institutes of Moldova, Georgia, Kyrgyzstan, Kazakhstan, Azerbaijan, Bosnia and Herzegovina and Turkey participate.Two standard platinum resistance thermometers (100 ohm), manufactured at VNIIM, was used as a transfer standards. National Metrology Institute (NMI) of Republic of Moldova is a pilot laboratory in this comparison.The purpose of the comparisons is to verify equivalence between the participating laboratories in the calibration of industrial platinum resistance thermometers by direct comparison in the range from minus 40 °C to 420 °C. The comparison results are used to confirm the calibration and measurement capabilities in this range.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Organochlorine Pesticides in Ginseng Root

Ginseng is one of the most important traditional herbal medicines for health care and treatment of diseases. Trading of ginseng and related products is a multi-million dollar business. Four major countries including South Korea, China, Canada and the United States are the biggest producers and account for more than 99% of the total ginseng production around the world (i.e. about 80,000 tons). The Commission Regulation of European Union sets up that the maximum residue level (MRL) for hexachlorocyclohexane (sum of alpha, beta and delta isomers, except lindane) is 0.02 mg/kg and that for lindane is 1 mg/kg in ginseng. The use of reliable methods for measurement of these organochlorine pesticides is important in safeguarding the quality of ginseng and related products and public health.The Government Laboratory, Hong Kong (GLHK) previously coordinated and completed CCQM-K95 "Mid-polarity Analytes in Food Matrix: Mid-polarity Pesticides in Tea". Two organochlorine pesticide residues,beta-endosulfan and endosulfan sulfate, were selected for analysis. It is noteworthy that participating institutes in CCQM-K95 found that wetting of test samples prior to extraction was crucial for complete extraction of the incurred analytes in the test material of dried tea. It is apparent that sample extraction is a real technical challenge in the analysis of dried plant material.Ginseng root is collected after years of cultivation. It represents a higher level of analytical challenge for the participating national metrology institutes (NMIs) and designated institutes (DIs) in measuring the incurred organochlorine pesticides in dried ginseng/ginseng root, where the pesticides have been gradually accumulated in the plant material for several years. In this regard, GLHK proposed a new APMP supplementary comparison on determination of organochlorine pesticides in ginseng root at the APMP TCQM meeting in November 2015. The supplementary comparison was further discussed at the CCQM OAWG meeting in April 2016. The Chair of APMP TCQM approved the proposed supplementary comparison for 2016/17 with a study number of APMP.QM-S11 in May 2016. To allow wider participation, a pilot study APMP.QM-P32, was run in parallel with this supplementary comparison.Evidence of successful participation in formal, relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs).Seven NMIs/DIs participated in this Supplementary Comparison APMP.QM-S11 Organochlorine pesticides in ginseng root. Participants were requested to evaluate the mass fractions, expressed in μg/kg, of alpha-hexachlorocyclohexane (α-BHC, CAS No. 319-84-6) and gamma-hexachlorocyclohexane (Lindane, CAS No. 58-89-9) in a relatively complex food/plant material, termed ginseng root. The purpose of the comparison is to enable participating laboratories to demonstrate their capability in the determination of organochlorine pesticides in a relatively complex food/plant material. All participating laboratories performed wetting before extraction. Different extraction methods such as soxhlet extraction, accelerated solvent extraction, ultrasonic extraction, QuEChERS technique, shaking and vortex were used among the participants. For the instrumental analysis, all laboratories employed GC techniques for chromatographic separation and most laboratories used MS related techniques for detection and quantification. For α-BHC, the consensus mean was 413 μg/kg with standard deviation of 35.3 μg/kg from 4 participating institutes' results. For lindane, the consensus mean was 104 μg/kg with standard deviation of 10.9 μg/kg from 5 participating institutes' results.Successful participation in APMP.QM-S11 demonstrates the following measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 10 μg/kg to 1000 μg/kg in food/plant matrices.KEY WORDS FOR SEARCHGinseng, Organochlorine Pesticide, alpha-hexachlorocyclohexane, gamma-hexachlorocyclohexane, Lindane, α-BHCMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Intralaboratory quality control of calibration results

The article is devoted to the issues of intralaboratory control of measurement results in a calibration laboratory. This is highly important in controlling and supporting the relevant calibration capability of the laboratory. Up to now, there are normative documents, which describe methods for controlling internal quality indicators of analytical measurements. After analyzing all possible options of comparing the quality indicators of the measurement results with critical values in the analytical laboratories and adapting them to the measurement features of the calibration laboratory, the methods of determining the critical limits for comparative measurements in the conditions of repeatability and intermediate precision are demonstrated.Measurement uncertainty in calibration consists of uncertainty effects introduced by reference equipment, test equipment, calibration operator, external conditions, calibration and calculation method, measuring instrument (MI), which is to be calibrated. Proceeding from the well-known practice, the calibration capability of the laboratory should be three to five times smaller than the uncertainty of MIs being calibrated by this laboratory. In order to maintain such a level of calibration, it is necessary to perform timely calibrations of the measurement standards and test equipment (to carry out internal testing of test equipment), validate calibration methods, participate in interlaboratory comparisons in order to determine laboratory bias and perform intralaboratory control of the quality indicators of measurement results in calibration.Several methods of intralaboratory control of measurement results in a calibration laboratory are proposed, namely, the evaluation of consistency of the measurement results in calibration in conditions of intermediate precision with variable factors “operator”, “time” and determination of the limits of repeatability.

External validation of a modified trauma and injury severity score model in major trauma injury

BackgroundThe establishment of an accurate prognostic model in major trauma patients is important mainly because this group of patients will benefit the most. Clinical prediction models must be validated internally and externally on a regular basis to ensure the prediction is accurate and current. This study aims to externally validate two prediction models, the Trauma and Injury Severity Score model developed using the Major Trauma Outcome Study in North America (MTOS-TRISS model), and the NTrD-TRISS model, which is a refined MTOS-TRISS model with coefficients derived from the Malaysian National Trauma Database (NTrD), by regarding mortality as the outcome measurement. MethodThis retrospective study included patients with major trauma injuries reported to a trauma centre of Hospital Sultanah Aminah over a 6-year period from 2011 and 2017. Model validation was examined using the measures of discrimination and calibration. Discrimination was assessed using the area under the receiver operating characteristic curve (AUC) and 95% confidence interval (CI). The Hosmer-Lemeshow (H-L) goodness-of-fit test was used to examine calibration capabilities. The predictive validity of both MTOS-TRISS and NTrD-TRISS models were further evaluated by incorporating parameters such as the New Injury Severity Scale and the Injury Severity Score. ResultsTotal patients of 3788 (3434 blunt and 354 penetrating injuries) with average age of 37 years (standard deviation of 16 years) were included in this study. All MTOS-TRISS and NTrD-TRISS models examined in this study showed adequate discriminative ability with AUCs ranged from 0.86 to 0.89 for patients with blunt trauma mechanism and 0.89 to 0.99 for patients with penetrating trauma mechanism. The H-L goodness-of-fit test indicated the NTrD-TRISS model calibrated as good as the MTOS-TRISS model for patients with blunt trauma mechanism. ConclusionFor patients with blunt trauma mechanism, both the MTOS-TRISS and NTrD-TRISS models showed good discrimination and calibration performances. Discrimination performance for the NTrD-TRISS model was revealed to be as good as the MTOS-TRISS model specifically for patients with penetrating trauma mechanism. Overall, this validation study has ascertained the discrimination and calibration performances of the NTrD-TRISS model to be as good as the MTOS-TRISS model particularly for patients with blunt trauma mechanism.

Energy response of GECAM gamma-ray detector based on LaBr3:Ce and SiPM array

The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) , composed of two small satellites, is a new mission to monitor the Gamma-Ray Bursts (GRBs) coincident with Gravitational Wave (GW) events with a FOV of 100% all-sky. Each GECAM satellite detects and localizes GRBs using 25 compact and novel Gamma-Ray Detectors (GRDs) in 6 keV–5 MeV. Each GRD module is comprised of LaBr3:Ce scintillator, SiPM array and preamplifier. A large dynamic range of GRD is achieved by the high gain and low gain channels of the preamplifier. The energy response of GRD prototype was evaluated using radioactive sources in the range of 5.9–1332.5 keV. A energy resolution of 5.3% at 662 keV was determined from the 137Cs pulse height spectra, which meets the GECAM requirement (< 8% at 662 keV). Energy to channel conversion was evaluated and a nonlinearity correction was performed to reduce the residuals (< 1.5%). Also, a Geant4-based simulated in-flight background and a measured GRD LaBr3:Ce intrinsic activity were used to evaluate the capability of in-flight calibration. These results demonstrate the design of GRD.

The Development of Small Water Flow Facility at National Institute of Metrology, Thailand

The flow and volume of liquid laboratory of the National Institute of Metrology, Thailand (NIMT) has developed the latest facility which covers the liquid flow measurement ranges from (10 – 1,000) g/h. This facility has been developed according to the need of high accuracy equipment in several industries such as pharmaceutical products, fuel cells, semiconductor and medical devices. For accuracy purposes, the gravimetric method is decisively implemented as the main principle of the calibration rig. It comprises of three main parts; water supply system, weighing system and data acquisition system. Practically, the capability of the facility is confirmed via a transfer standard. With high accuracy and repeatability, the Coriolis mass flow controllers were selected as the transfer standard. The facility can provide the best capability of calibration, CMC, at 0.30% of reading. Moreover, the evidence of unofficial comparison between NIMT and Federal Institute of Metrology, METAS, Switzerland, has confirmed this capability via the degree of equivalence, En ratio. The En ratios represent that the comparison of the flow rates from (10 – 1,000) g/h between NIMT and METAS is agreed.

Improving the State Base of Measurement Standards in the Field of Photonics

The base of measurement standards of the All-Russia Research Institute of Optophysical Measurements developed and employed by the Institute for metrological support of photonics technologies and products is described. The present condition and calibration capabilities of the state primary standards as well as the direction and outlook for further improvement of the standards are reviewed.

Metrological set-up for calibrating 2-dimensional grid plates with sub-micrometre precision

Calibration, performance verification and error correction of two dimensional (2D) optical metrology instruments, such as profile projectors, microscopes and “vision” systems are commonly carried out with the aid of calibrated 2D high-precision optical grid plates. This paper presents a high resolution 2D measurement instrument that has been developed for calibrating such grid-plates up to 300 mm × 200 mm in size and providing sub-micrometre measurement uncertainties. This instrument was specifically designed by the laboratory to ensure their calibration capabilities aligned with both the customers’ technical requirements along with their budgets and expectations too.

Design and Validation of the MBW Standard Humidity Generators

MBW Calibration AG (MBW) is the Designated Institute (DI) for humidity appointed by the Federal Institute of Metrology, METAS. MBW currently offers calibration and measurement capabilities (CMC) for frost/dew-point hygrometers by comparison with precision chilled-mirror transfer standards that have been calibrated using the primary standards of leading European National Metrology Institutes or DI. The design, construction and validation of two standard humidity generators to be used as the Swiss national standards for the primary realization of frost/dew-point temperature in the range from − 90 °C to + 95 °C are presented and discussed. The generators are operated as continuous flow “single-pressure” generators in the range from − 80 °C to − 10 °C with saturation over ice and from 0.5 °C to + 95 °C with saturation over water. Additionally, they are used in “two-pressure” mode for saturation over ice down to frost-point temperatures of − 90 °C and down to − 20 °C for saturation over water. The main saturators of both generators have been designed to fit in commercially available calibration baths with either ethanol or distilled water as the heat transfer fluid for saturator temperatures below and above 0 °C, respectively. Saturator temperature is measured using standard platinum resistance thermometers and a purpose-built precision thermometer. Pressure measurements are taken with gauge pressure transducers and a separate barometric sensor, to reduce the influence of the atmospheric pressure on the measurement of the pressure ratio and make full use of the correlation of pressure measurements and enhancement factors when operating in two-pressure mode. A totally automated pre-saturation and flow control system facilitates the calibration of state-of-the-art chilled-mirror transfer for standards without manual readjustment of the generated flowrate to ensure a constant volumetric flow at the conditions of the mirror. The uncertainty budget leading to the CMC for frost/dew-point temperature realization is presented in the context of the experimental validation performed. The results in the overlapping range of both generators are presented and used as further evidence of the saturation efficiency of both standards.

Seismometer Calibration Using a Multi-Component Acceleration Exciter

Seismometers are widely used all over the world, but rarely calibrated traceably. PTB analysed its capabilities for seismometer calibration and identified its multi-component acceleration exciter as suitable for carrying the comparably heavy seismometers. Additionally, multi-axial seismometers can be calibrated in all axes without moving the device. The calibration device needed to be analysed and tested for the required small excitation magnitudes and low excitation frequencies. The results show that it is capable of generating small sinusoidal excitation of less than 1mm/s in a frequency range down to 0.4 Hz. For this purpose, the feedback control needed to be adapted. Additionally, a temperature control of the shaker armature prevents the problem of temperature increase due to hot hydraulic fluids near the armature.The vibrations in all three translational degrees of freedom are measured by laser vibrometers and then processed according to ISO 16063-11 by sine fit procedures.

Seismometer Calibration Using a Multi-Component Acceleration Exciter

Seismometers are widely used all over the world, but rarely calibrated traceably. PTB analysed its capabilities for seismometer calibration and identified its multi-component acceleration exciter as suitable for carrying the comparably heavy seismometers. Additionally, multi-axial seismometers can be calibrated in all axes without moving the device. The calibration device needed to be analysed and tested for the required small excitation magnitudes and low excitation frequencies. The results show that it is capable of generating small sinusoidal excitation of less than 1 mm/s in a frequency range down to 0.4 Hz. For this purpose, the feedback control needed to be adapted. Additionally, a temperature control of the shaker armature prevents the problem of temperature increase due to hot hydraulic fluids near the armature.The vibrations in all three translational degrees of freedom are measured by laser vibrometers and then processed according to ISO 16063-11 by sine fit procedures.