Cristina Flores, M. Graça Dias, Mariana Santos
The performance evaluation of an RP-HPLC method to determine thiamine using different food matrices and reference materials, showed the method suitability to its purpose and to be submitted to accreditation. Intermediate precision evaluate through the relative standard deviation (RSD%) was under 8% for all food matrices tested an all the z-scores obtained for the reference materials were < 1.5.The estimated expanded measurement uncertainty was 13%.
XXI IMEKO World Congress
· TC23
· 2015
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Inês Delgado, Inês Coelho, Isabel Castanheira, Maria Antónia Calhau
Iodine is an essential trace element in human and animal diets. However iodine deficiency is reported in most of the countries. Food is the natural source of iodine. Traceable analytical values to SI units are required to guarantee reliable measurement results which are used to estimate iodine intake overtime at national and international level. The aim of this study was to create an iodine database containing analytical values, methods of analysis and metrological concepts, described in scientific publications reporting food data. This database will be used as a starting tool to define the...
XXI IMEKO World Congress
· TC23
· 2015
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Catarina André, Inês Delgado, Susana de Jesus, Ana Ramos, Carlos Brandão, Nelson Felix, Isabel Castanheira
The aim of this study was the determination of acrylamide in food with high consumed in Portugal. Samples were bought randomly from local supermarkets and from Escola Superior de Hotelaria e Turismo do Estoril. Sample preparation involved SPE (Solid Phase Extraction). Two chromatographic methods were developed, UPLC-PDA and UPLC-MS/MS which was more suitable and quantify unequivocally acrylamide. The acrylamide content in bread and pastries samples analyzed were above the indicative values published by EFSA.
XXI IMEKO World Congress
· TC23
· 2015
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Henrik Volkers, Thomas Bruns
By applying a two-degree-of-freedom system model (2-DOF) for an Endevco type 2270 back-to-back reference accelerometer, systematic deviations between measured and fitted 1-DOF transfer functions could be improved. Some key information for the identification of the model parameters is found in the frequency range beyond the first resonance, a range which was rarely considered in the past.
XXI IMEKO World Congress
· TC22
· 2015
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C. S. Veldman, T. M. Lefenya
The National Metrology Institute of South Africa designed an air bearing linear translation stage (LTS) used for primary low frequency accelerometer calibration. The LTS serves as a replacement of a commercial LTS. The motivation for the new design consideration is touched on. The performances of both LTSs were evaluated in terms of their flatness, straightness, roll, pitch and dynamic transverse motion; the results and findings of which are reported in some detail. The influence of the mechanical connection between the LTS and the electrodynamics exciter was also investigated.
XXI IMEKO World Congress
· TC22
· 2015
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Tsung Hsien Tu, Kuang-Yih Tsuei, Jiun-Kai Chen, Yu-Chung Huang, Pei-Yao Yu, Kuang-I Chang
Accelerometer comparison calibration technique involves the back-to-back coupling the accelerometer under test directly to a traceable reference standard accelerometer and both accelerometers will be experienced the same motion from shaker. Thus the sensitivity of standard accelerometer can be transferred to the test accelerometer via a calibration constant from the output signals. The results of the relative expand uncertainty for the voltage sensitivities for accelerometer are less than 1.4 %, 1.9 % and 2.9 % within frequency range from 50 Hz to 1.5 kHz, from 1.5 kHz to 5 kHz, and from 5...
XXI IMEKO World Congress
· TC22
· 2015
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Qiao Sun, Hong-bo Hu
This paper first presents the investigation work of the pilot comparison of low intensity shock calibration by laser interferometry. Two main technical concerns for a possible comparison are variety of primary shock calibration systems covered and feasibility of comparison artifact investigated. For the primary calibration system, homodyne or heterodyne laser interferometer is included as measurement standard, but the mechanical excitation is of three different types: hammer-anvil collision, pneumatic driven projectile impact and Hopkinson bar. The shock pulses generated are smooth monopole...
XXI IMEKO World Congress
· TC22
· 2015
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Yubin Sun, Li Kong, Jingjing Cheng
The random vibration of the drill collar results in the additional attenuation to the NMR LWD signals, which will bring additional error in the process of T2 spectrum inversion. The determination of the displacement will help to recuperate the signals. This paper studied the property of the drill collar and proposed a scheme to determine the random vibration displacement which used two tri-axis vibration accelerometers and a two axis magnetometer. The simulation results and the shaking table test demonstrate that this scheme is effective and can be implemented in the instrument.
XXI IMEKO World Congress
· TC22
· 2015
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Ioan Ursu, Adrian Toader, Daniela Enciu, Dan Mihai Ştefănescu
Accurate specimens representing aluminum spacecraft structures with piezoelectric wafer active sensor (PWAS) bonded on them were subjected to extreme temperature variations and radiations. The structure itself is affected by mechanical damages caused by fatigue and aging. The signature of structure’s health is the real part of electromechanical impedance spectroscopy (EMIS) curves of a PWAS bonded on structure. Based on these EMIS records, damage metrics were calculated as root mean square deviation from healthy to damaged specimen. This paper presents a concise description of four...
XXI IMEKO World Congress
· TC22
· 2015
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Alessandro Schiavi, Fabrizio Mazzoleni, Alessandro Germak
A procedure and a method for simultaneous 3-axis accelerometer primary calibration is presented. Nowadays, in the field of vibration monitoring, a relevant increase and diffusion of «low-cost» three-axial accelerometers (e.g. MEMS and NEMS) has been observed. The increased demand for calibration of MEMS and NEMS accelerometers and their inherent «low-accuracy», presupposes the opportunity to simplify the traditional calibration of triaxial accelerometers, as stated in Standard ISO 16063-21.
XXI IMEKO World Congress
· TC22
· 2015
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