Calibration Interval Research Articles

Numerical Experiments on the Application of Markov Chain Monte Carlo for the Establishment of Calibration Intervals

This study presented a new approach for conducting measurement reliability analysis and establishing calibration intervals based on Markov chain Monte Carlo (MCMC). Calibration records following the Weibull and lognormal reliability models were generated under various calibration conditions, and they were used to test the validity of the method proposed in this study. Numerical experiments were used to obtain the estimates for the measurement reliability model, and the optimum calibration interval was obtained for the simulated calibration records. The results showed that the measurement reliability models obtained using the MCMC method were consistent with those obtained using the S3 method, which is considered to be the most advanced approach. In particular, both methods exhibited strong agreement in the estimation of calibration records simulated under the renew-if-failed policy. The MCMC method allows sampling to estimate the distribution, and this feature can be employed to calculate the uncertainty of the measurement reliability model and the optimal calibration interval. This uncertainty provides the reliability of the estimation and is expected to help manage the risk of establishing the calibration interval and maintaining measurement quality.

Новые данные по хронологии и стратиграфии памятника Ракушечный Яр

Rakushechny Yar site, located in the Lower Don basin, is a multilayered floodplain settlement with a series of buried soils, where Neolithic-Eneolithic and Bronze Age cultural layers have been investigated. Dates with a wide calibration interval for materials from excavation # 1 obtained from total organic content of ceramics, food crust, and charcoal previously demonstrated the length of the Early Neolithic period ranging from the mid 7th millennium BC to the end of the 6th millennium cal BC. The new data allowed us to significantly adjust chronology of the site. A new series of dating based on animal bones from the Early Neolithic layers concentrate within a narrow chronological interval of a few decades around 5600 cal BC. This suggests that burying of archaeological remains was very rapid, and sand interlayers which separated them do not form significant temporal hiatuses. The archaeological layers are distributed within restricted surfaces and correspond to different episodes of coastal zone inhabitation. The variation in the number, thickness and character of the archaeological layers points to repeated episodes of inhabitation during Early Neolithic. The time when the Early Neolithic strata might have been closed differs at various parts – from the 5th mill to the 4th millennium cal BC (based on OSL and AMS dates). The contradictions that existed between the individual dates can be explained either by the reservoir effect (for food crust dating) or by the correlation of the dating from different sections, where layers were not deposited at the same time. It is complicated to determine the rate of deposition of Early Neolithic cultural strata, which may have occurred in a single season or possibly over a longer period of time. The series of dates obtained indicate successive occupation of the site. The change in the pattern of coastal inhabitation from small-scale households’ areas with shell paved platforms and pits to dwelling complexes with clay pavement floors and clay-covered walls/roofs occurred over a very short time. This may explain the homogenous nature of the Early Neolithic material culture and the production of a certain set of clay vessels, stone, bone industry, and shell tools.

Automation of solving problems of optimization of parameters of metrological maintenance system of measuring equipment

Automation of the metrological service of the enterprise allows to reduce the use of labor to perform tasks of maintenance of measuring equipment and reduce staff errors. At the same time, the process of creating appropriate automated systems requires solving a number of problems related to the need to optimize the parameters of the designed system to ensure its highest efficiency. This article attempts to solve the problem of covering various models in the synthesis and study of simulation computer models that actively use the database of measuring instruments of enterprises. Developed and software implemented a model that allows interactive mode, taking into account the characteristics coming from the calibration laboratories of the service, and given economic and metrological criteria, to determine the values of optimal calibration and repair intervals, the optimal number of inspections in the repair interval and other parameters. The dependence of FTA reliability indicators on the quality of metrological maintenance and repair was investigated by simulation. The influence of inter - repair and inter - calibration intervals on economic efficiency of metrological service is investigated. As a result, the dependences are obtained, which also allow to investigate the influence of service quality parameters on complex reliability indicators. The use of research results allows in the dialog mode of the automated workplace of the metrologist to solve problems of optimization of parameters of metrological service on eco-nomic criteria and restrictions of concrete production on indicators of metrological reliability of measuring instruments, to carry out diagnostics and to forecast metrological reliability of measuring instruments. measurement accuracy and reduce the likelihood of hidden failures.

Unprecedented acceleration of winter discharge of Upper Yenisei River inferred from tree rings

The Yenisei River is the largest contributor of freshwater and energy fluxes among all rivers draining to the Arctic Ocean. Modeling long-term variability of Eurasian runoff to the Arctic Ocean is complicated by the considerable variability of river discharge in time and space, and the monitoring constraints imposed by a sparse gauged-flow network and paucity of satellite data. We quantify tree growth response to river discharge at the upper reaches of the Yenisei River in Tuva, South Siberia. Two regression models built from eight tree-ring width chronologies of Larix sibirica are applied to reconstruct winter (Nov–Apr) discharge for the period 1784–1997 (214 years), and annual (Oct–Sept) discharge for the period 1701–2000 (300 years). The Nov–Apr model explains 52% of the discharge variance whereas Oct–Sept explains 26% for the calibration intervals 1927–1997 and 1927–2000, respectively. This new hydrological archive doubles the length of the instrumental discharge record at the Kyzyl gauge and resets the temporal background of discharge variability back to 1784. The reconstruction finds a remarkable 80% upsurge in winter flow over the last 25 years, which is unprecedented in the last 214 years. In contrast, annual discharge fluctuated normally for this system, with only a 7% increase over the last 25 years. Water balance modeling with CRU data manifests a significant discrepancy between decadal variability of the gauged flow and climate data after 1960. We discuss the impact on the baseflow rate change of both the accelerating permafrost warming in the discontinuous zone of South Siberia and widespread forest fires. The winter discharge accounts for only one third of the annual flow, yet the persistent 25 year upsurge is alarming. This trend is likely caused by Arctic Amplification, which can be further magnified by increased winter flow delivering significantly more fresh water to the Kara Sea during the cold season.

Estimation of calibration intervals using Bayesian inference

The determination of calibration intervals of instruments is an important task for assuring confidence in measurements. The methods available to estimate these intervals usually require a large database or are based on non-probabilistic approaches. Given the limitations related with the collection of data, it is highly desirable to include in the analysis previous knowledge about the performance of the instrument, this can be done through Bayesian inference. This paper presents an approach based on this method which combines robust techniques for estimation of calibration intervals with commonly available metrological information such as tolerance, specifications or experimental data of similar instruments. The proposed approach can be used with a small sample size contrary to other methodologies that are not adequate for this purpose.

Rotational Vibration Test Apparatus for Laser Vibrometer Verification

<div class="section abstract"><div class="htmlview paragraph">Prior to making rotational vibration measurements with a laser vibrometer, it is good practice to establish that the instrument is operating properly. This can be accomplished by comparative measurement of a rotational vibration source with known amplitude and frequency. This paper describes the design and development of a rotational vibration apparatus with known amplitude and frequency to be used as a reference for comparison to concurrent and co-located measurements made by a rotational laser vibrometer (RLV). The comparative measurements acquired with the apparatus are helpful to verify proper laser vibrometer operation in between regular calibration intervals, and/or whenever the functionality of the vibrometer is suspect. In the subject apparatus, a Cardan shaft with variable input speed and angle is used to provide output torsional vibration with variable frequency and amplitude. Previously derived equations of motion for Cardan joints are used to estimate operating amplitude versus speed relationship for the apparatus. To provide an independent rotational vibration measurement for comparison to the laser, a ferromagnetic toothed wheel and magnetic pickup are used. The design of the Cardan shaft and adjustable support table are described, followed by the design of the variable speed electric drive system and controller. For the finished apparatus, example operating data from the reference sensor are compared to laser vibrometer data, and to the theoretical prediction of output torsional velocity from the Cardan joint equations of motion. Finally, suggestions for future work are provided. The development and verification of rotational tuned vibration absorbers is provided as a potential additional application of the apparatus.</div></div>

Characterizing water vapour concentration dependence of commercial cavity ring-down spectrometers for continuous on-site atmospheric water vapour isotope measurements in the tropics

Abstract. The recent development and improvement of commercial laser-based spectrometers have expanded in situ continuous observations of water vapour (H2O) stable isotope compositions (e.g. δ18O and δ2H) in a variety of sites worldwide. However, we still lack continuous observations in the Amazon, a region that significantly influences atmospheric and hydrological cycles on local to global scales. In order to achieve accurate on-site observations, commercial water isotope analysers require regular in situ calibration, which includes the correction of H2O concentration dependence ([H2O] dependence) of isotopic measurements. Past studies have assessed the [H2O] dependence for air with H2O concentrations of up to 35 000 ppm, a value that is frequently surpassed in tropical rainforest settings like the central Amazon where we plan continuous observations. Here we investigated the performance of two commercial analysers (L1102i and L2130i models, Picarro, Inc., USA) for measuring δ18O and δ2H in atmospheric moisture at four different H2O levels from 21 500 to 41 000 ppm. These H2O levels were created by a custom-built calibration unit designed for regular in situ calibration. Measurements on the newer analyser model (L2130i) had better precision for δ18O and δ2H and demonstrated less influence of H2O concentration on the measurement accuracy at each concentration level compared to the older L1102i. Based on our findings, we identified the most appropriate calibration strategy for [H2O] dependence, adapted to our calibration system. The best strategy required conducting a two-point calibration with four different H2O concentration levels, carried out at the beginning and end of the calibration interval. The smallest uncertainties in calibrating [H2O] dependence of isotopic accuracy of the two analysers were achieved using a linear surface fitting method and a 28 h calibration interval, except for the δ18O accuracy of the L1102i analyser for which the cubic fitting method gave the best results. The uncertainties in [H2O] dependence calibration did not show any significant difference using calibration intervals from 28 up to 196 h; this suggested that one [H2O] dependence calibration per week for the L2130i and L1102i analysers is sufficient. This study shows that the cavity ring-down spectroscopy (CRDS) analysers, appropriately calibrated for [H2O] dependence, allow the detection of natural signals of stable water vapour isotopes at very high humidity levels, which has promising implications for water cycle studies in areas like the central Amazon rainforest and other tropical regions.

The Influence of the Calibration Interval on Simulating Non-Stationary Urban Growth Dynamic Using CA-Markov Model

The temporal non-stationarity of land use and cover change (LUCC) processes is one of the main sources of uncertainty that may influence the calibration and the validation of spatial path-dependent LUCC models. In relation to that, this research aims to investigate the influence of the temporal non-stationarity of land change on urban growth modeling accuracy based on an empirical approach that uses past LUCC. Accordingly, the urban development in Rennes Metropolitan (France) was simulated using fifteen past calibration intervals which are set from six training dates. The study used Idrisi’s Cellular Automata-Markov model (CA-Markov) which is an inductive pattern-based LUCC software package. The land demand for the simulation year was estimated using the Markov Chain method. Model validation was carried out by assessing the quantity of change, allocation, and spatial patterns accuracy. The quantity disagreement was analyzed by taking into consideration the temporal non-stationarity of change rate over the calibration and the prediction intervals, the model ability to reproduce the past amount of change in the future, and the time duration of the prediction interval. The results show that the calibration interval significantly influenced the amount and the spatial allocation of the estimated change. In addition to that, the spatial allocation of change using CA-Markov depended highly on the basis land cover image rather than the observed transition during the calibration period. Therefore, this study provides useful insights on the role of the training dates in the simulation of non-stationary LUCC.

Adjusting external calibration intervals for auxiliary devices in testing laboratories according to intermediate checks results

ABSTRACT An unfortunate thing which is not desirable to happen in testing laboratories is that after working for weeks on tests, it is discovered that one of the used equipment is not accurate. Therefore, intermediate checking these devices from time to time is a reasonable way to reduce the risk of errors in laboratory work. The Central Laboratory for Environmental Quality Monitoring (CLEQM) performs intermediate check for testing equipment, besides the annual calibration done by an accredited body, to maintain confidence in its accuracy and precision between calibration intervals. This paper discusses the laboratory procedures to perform intermediate checks for electronic balances and micropipettes to comply with ISO/IEC:17025 requirements in the field of water quality testing. Intermediate check for balances was carried out according to OIML R111-2004 (E), while intermediate check for micropipettes was performed according to ISO 8655-6-2002. The results of intermediate checks and control charts were used to monitor equipment needs for recalibration. The results indicated that calibration of laboratory equipment is not necessarily neither to be annually nor at fixed time intervals. However, it should be based on the drift in measurements, which can be detected through regular intermediate check. Where results are tracked through control charts and in case that, it is drifted out of control limits, a nonconformance is reported, and appropriate corrective actions are taken including calibration if required. It is concluded that calibration of supporting equipment according to their intermediate check is more favorable than fixed time intervals due to the high degree of reliability of the generated test results in addition to reduced financial costs, which is expected to be 25% to 40% lower than the cost of calibration with fixed intervals.

Tutorial and spreadsheet for the evaluation of instrumental quantification uncertainty by the linear weighted regression model: Determination of elemental impurities in a nasal spray by ICP-MS

A tutorial and spreadsheet for the validation and bottom-up uncertainty evaluation of quantifications performed by instrumental methods of analysis based on linear weighted calibrations is presented. The developed tool automatically assesses if calibrator values uncertainty is negligible given instrumental signal precision, assesses signal homoscedasticity by the Levene's test, guides the selection of weighting factors and evaluates the fitness of the regression model to define the calibration curve. The spreadsheet allows the use of the linear weighted regression model without the need for collecting many replicate signals of calibrators and sample by taking previously developed detailed models of signal precision variation in the calibration interval after adjustments to the daily precision conditions. This tool was successfully applied to the determination of the mass concentration of Cd, Pb, As, Hg, Co, V and Ni in a nasal spray by ICP-MS after samples dilution and acidification. The developed uncertainty models were checked through the analysis of nasal sprays after spiking with known analyte concentration levels. The metrological compatibility between estimated and reference analyte levels for 95% or 99% confidence level supports uncertainty model adequacy. The spiked samples were quantified from many replicate signals but uncertainty evaluation from duplicate calibrator and sample signals was assessed by randomly selecting calibrators and sample signals and by numerically defining a minimum acceptable success rate of the compatibility tests. The developed model was proven adequate to quantify the uncertainty of the studied measurements.

PROBLEM ISSUES OF METROLOGICAL ACTIVITY IN THE CONDITIONS OF REFORMING THE NATIONAL METROLOGICAL SERVICE

The practice of working in the context of frequent changes in legislation in the field of technical regulation, as well as the adoption of a new edition of ISO 17025:2017 highlighted some problematic issues related to the identification of measuring instruments groups according to the international classification of measurement types, procedural issues of verification of medical devices with a measurement function, ambiguity of provisions some regulatory legal acts on the procedure for using standard samples of the composition and properties of substances and materials, etc.Special attention should be paid to the issues related to the establishment and regulation of procedures that replace the "voluntary verification" of measuring instruments and the "attestation" of test and auxiliary equipment with measurement functions, as well as approaches to the definition of procedures for checking (conformity confirmation) of the technical characteristics of devices, not a measuring instrument, but whose work is explicitly or implicitly related to the measurement and standardization of quantities (for example, refrigerators, thermostats, power supplies, etc.).In addition, issues related to the risk-oriented approach to metrological work with the aim of optimizing them are considered, among which the substantiation of the determination and adjustment of calibration intervals are especially prominent.In the report, we analyzed the above issues and suggested some ways to solve them, based on the practical activities of the Metrology Center of SE “Kharkovstandardmetrology”.

A Hybrid Downscaling Approach for Future Temperature and Precipitation Change

AbstractWe used empirical–statistical downscaling in a pseudoreality context, in which both large-scale predictors and small-scale predictands were based on climate model results. The large-scale conditions were taken from a global climate model, and the small-scale conditions were taken from dynamical downscaling of the same global model with a convection-permitting regional climate model covering southern Norway. This hybrid downscaling approach, a “perfect model”–type experiment, provided 120 years of data under the CMIP5 high-emission scenario. Ample calibration samples made rigorous testing possible, enabling us to evaluate the effect of empirical–statistical model configurations and predictor choices and to assess the stationarity of the statistical models by investigating their sensitivity to different calibration intervals. The skill of the statistical models was evaluated in terms of their ability to reproduce the interannual correlation and long-term trends in seasonal 2-m temperature T2m, wet-day frequency fw, and wet-day mean precipitation μ. We found that different 30-yr calibration intervals often resulted in differing statistical models, depending on the specific choice of years. The hybrid downscaling approach allowed us to emulate seasonal mean regional climate model output with a high spatial resolution (0.05° latitude and 0.1° longitude grid) for up to 100 GCM runs while circumventing the issue of short calibration time, and it provides a robust set of empirically downscaled GCM runs.

Long-term drift analysis of Zener voltage standards and proposal of an initial calibration interval using calibration records accumulated for 15 years

In electrical metrology, voltage is a key quantity together with resistance for realising all electric standards in the low-frequency range. Zener voltage standards are accepted as the most stable to disseminate voltage references traceable to the Josephson standard devices. We study the long-term drift of the Zener devices to propose their initial calibration interval (CI), statistically analysing the calibration records accumulated for 15 years at the Korea Research Institute of Standards and Science (KRISS). First, we apply the direct method where the measurement reliability is obtained by integrating the probability density functions acquired from kernel density estimation (KDE). Markov chain Monte Carlo (MCMC) has been successfully demonstrated to determine the parameters of the Weibull reliability model. A numerical experiment was performed to confirm that the MCMC method works properly and is able to replace the S3 method of NCSLI. The direct method agrees with the MCMC within the highest posterior density (HPD) obtained by the MCMC method. The KDEs of the parameters acquired by the MCMC method enable the uncertainty of the parameters to be expressed in probability distributions rather than in confidence intervals. The final result proposes an initial CI of the 10 V output taps in the Zener devices without any calibration record of 8.8 months with a 0.91-month standard deviation for 90% of the measurement reliability target (MRT) and a 16 μV tolerance limit.

Development of measurement science in the context of the fourth industrial revolution

The fourth industrial revolution is characterised by the wide introduction of cyber-physical systems, robotics and the Internet of Things. The efficiency of smart cities, smart manufacturing, smart transport, etc. can be provided only if the measurement information coming from sensors is trustworthy. In each facility, the number of sensors can vary from thousands to tens of thousands. The avalanche-like growth in the number of measuring instruments should be accompanied by quite frequent check of their metrological serviceability. In this case, a significant reduction in maintenance labour costs can be achieved by increasing calibration or verification intervals by many times. The development in this direction is challenging because of the growing demand for the increase in the number of complex properties that should be quantitatively estimated. The fundamentals of metrological check and features of applying object digital twins for debugging multichannel measuring systems have been given. The need for international standards in this field has been emphasised.

High-precision and wide-range real-time neutron flux monitor system through multipoint linear calibration

The neutron flux monitor (NFM) system is an important diagnostic subsystem introduced by large nuclear fusion devices such as international thermonuclear experimental reactor (ITER), Japan torus-60, tokamak fusion test reactor, and HL-2A. Neutron fluxes can provide real-time parameters for nuclear fusion, including neutron source intensity and fusion power. Corresponding to different nuclear reaction periods, neutron fluxes span over seven decades, thereby requiring electronic devices to operate in counting and Campbelling modes simultaneously. Therefore, it is crucial to design a real-time NFM system to encompass such a wide dynamic range. In this study, a high-precision NFM system with a wide measurement range of neutron flux is implemented using real-time multipoint linear calibration. It can automatically switch between counting and Campbelling modes with variations in the neutron flux. We established a testing platform to verify the feasibility of the NFM system, which can output the simulated neutron signal using an arbitrary waveform generator. Meanwhile, the accurate calibration interval of the Campbelling mode is defined well. Based on the above-mentioned design, the system satisfies the requirements, offering a dynamic range of 108 cps, temporal resolution of 1 ms, and maximal relative error of 4% measured at the signal-to-noise ratio of 15.8 dB. Additionally, the NFM system is verified in a field experiment involving HL-2A, and the measured neutron flux is consistent with the results.

ДОСЛІДЖЕННЯ ПОКАЗНИКА ЕФЕКТИВНОСТІ ЕКСПЛУАТАЦІЇ ЗАСОБІВ ВИМІРЮВАЛЬНОЇ ТЕХНІКИ МЕТОДОМ КОМПʼЮТЕРНОГО МОДЕЛЮВАННЯ

The operational efficiency of measuring equipment (ME) is important in determining the cost of maintaining ME. To characterize the operational efficiency of the ME, an efficiency indicator has been introduced, an increase of which will reduce costs caused by the release of defective products due to the use of ME with unreliable indications. Over time, the ME parameters change under the influence of external factors and the ME aging processes inevitably occur, as a result of which the parameters of the ME metrological service system change. Therefore, in the general case, the parameters of the metrological maintenance system of ME should be considered as random variables. Accordingly, the efficiency indicator of measuring instruments is also a random variable, for the determination of which it is advisable to apply the methods of mathematical statistics and computer simulation. The performance indicator depends on the parameters of the metrological maintenance ME system, such as the calibration interval, the time spent by the ME on metrological maintenance, and the likelihood of ME failure-free operation. As a random variable, the efficiency indicator has a certain distribution function. To determine the distribution function of the efficiency indicator and the corresponding statistical characteristics, a computer simulation method was used. A study was made of the influence on the indicator of the effectiveness of the parameters of the metrological maintenance system ME (interesting interval, the failure rate of ME). The value of the verification interval and the failure rate of MEs varied over a wide range typical of real production. The time spent by ME on metrological services is considered as a random variable with a normal distribution law. To obtain random numbers with a normal distribution law, the Box-Muller method is used. After modeling, the statistical processing of the obtained results was done. It is shown that in real production, the efficiency indicator has a normal distribution law and the value of the efficiency indicator with an increase in the calibration interval does not practically change.

Measuring instruments metrological monitoring in a medical organization based on a process approach

A model of the process of metrological control of measuring instruments is presented. The model includes 6 or9 stages, depending on the results of metrological control. Based on the list of measuring instruments, a contract is concludedfor metrological control. After the conclusion of the contract, the collection of documents necessary for verification iscollected. Further, the measuring instruments are transferred to an accredited organization. An accredited organization carriesout verification. If, according to the results of verification, the tool is deemed suitable for use, then the stage of obtainingconfirmation of the verification is carried out. The output at this stage will be a verification certificate. If, according to theresults of verification, the measuring instrument is not suitable for operation, then the stage of canceling the verificationcertificate is carried out. The next steps in this case are to receive notice of unsuitability for use and write-off of the measuringinstrument. At this process is considered complete. The target indicators (indicators) of the process are: the measurementerror of specific measuring instruments within the established limits. Monitoring (control) of the process is carried out bya metrology engineer of a medical organization. Control methods are: control of the calibration intervals of measuringinstruments. The model is recommended as a model for use in medical organizations. The use of this model in the presenceof a target indicator (indicator) of the process of metrological control will ensure the necessary quality of metrological workin a medical organization within the framework of the internal quality control system.

Monte Carlo bottom-up evaluation of global instrumental quantification uncertainty: Flexible and user-friendly computational tool

Many instrumental methods of analysis require the daily collection of calibrator signals to calibrate their response. The quality of quantifications based on these calibrations depends on calibrators quality, instrumental signal performance and regression model fitness. Linear Ordinary Least Squares (LOLS), Linear Weighted Least Squares (LWLS) or Linear Bivariate Least Squares (LBLS) regression models can be used to calibrate and evaluate the uncertainty from instrumental quantifications, but require the fulfilment of some assumptions, namely, constant signal variance (LOLS), high calibrators quality (LOLS and LWLS) and linear variation of instrumental signal with calibrator values. The LBLS is flexible regarding calibrator values uncertainty and correlation but requires the determination of calibrator values and signals covariances. This work developed a computational tool for the bottom-up evaluation of global instrumental quantifications uncertainty which simulates calibrator values correlations from entered calibrators preparation procedure and simulates calibrators and samples signals precision from prior precision data, allowing accurate uncertainty evaluation from a few replicate signals of the daily calibration. The used signal precision models were built from previously observed repeatability variation throughout the calibration interval adjusted to daily precision condition from a residual standard deviation adjustment factor. This approach was implemented in a user-friendly MS-Excel file and was successfully applied to the analysis of As, Cd, Ni and Pb in marine sediment extracts by Absorption Spectroscopy. Evaluations were tested by the metrological compatibility of estimated and reference values of control standards for confidence levels of 95% and 99%. The success rates of the compatibility tests were statistically equivalent to the confidence level (p-value>0.01).

2182-PUB: Feasibility of Extended Calibration Intervals with a Long-Term, Implantable CGM System

Background: Continuous Glucose Monitoring (CGM) technology has improved glycemia in people with diabetes. However, user burden including frequent calibration, and reinsertion of short-term devices limits adoption of this technology. Aim: Our objective was to retrospectively analyze CGM data from a fully implanted prototype sensor to assess feasibility of an extended calibration interval. Methods: The Eclipse® ICGM® System was surgically inserted in the lower abdomen, superficial to the rectus muscle sheath (Figure 1) in 6 adults with T1 diabetes, Mean (SD) age 42(12) years; 33% Females, HbA1c 7.1% (1.2)%/54(13) mmol/mol. For 6 months participants self-monitored blood glucose 4 times/day and wore a Dexcom G5 CGM. In addition, monthly clinic visits include meal-tests with frequent sampling YSI plasma glucose for paired analyses. Analyses of investigational device CGM data was retrospective against benchmark measurements. Results: There were no device associated adverse events. Data from three participants demonstrate intervals of 30, 48 and 85 days between calibrations without impacting overall performance. Preliminary measures show clinically relevant accuracy of >95 % within the A+B ranges. Conclusion: Interim data supports extended interval calibration for the fully implanted prototype Eclipse® ICGM® System which holds promise of CGM with fewer device interactions and enhanced patient experience. Disclosure P. Gupta: Employee; Self; GlySens Incorporated. A. Butler: Employee; Self; GlySens Incorporated. K. Bertsch: None. H. Jones: None. M.H. Lee: Research Support; Self; Medtronic. Speaker’s Bureau; Self; AstraZeneca, Medtronic. V.R. Obeyesekere: None. S.L. Martha: None. A. Jenkins: Advisory Panel; Self; Abbott, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Sanofi-Aventis. D.N. ONeal: None.

Effects of Category Aggregation on Land Change Simulation Based on Corine Land Cover Data

Several factors influence the performance of land change simulation models. One potentially important factor is land category aggregation, which reduces the number of categories while having the potential to reduce also the size of apparent land change in the data. Our article compares how four methods to aggregate Corine Land Cover categories influence the size of land changes in various spatial extents and consequently influence the performance of 114 Cellular Automata-Markov simulation model runs. We calculated the reference change during the calibration interval, the reference change during the validation interval and the simulation change during the validation interval, along with five metrics of simulation performance, Figure of Merit and its four components: Misses, Hits, Wrong Hits and False Alarms. The Corine Standard Level 1 category aggregation reduced change more than any of the other aggregation methods. The model runs that used the Corine Standard Level 1 aggregation method tended to return lower sizes of changing areas and lower values of Misses, Hits, Wrong Hits and False Alarms, where Hits are correctly simulated changes. The behavior-based aggregation method maintained the most change while using fewer categories compared to the other aggregation methods. We recommend an aggregation method that maintains the size of the reference change during the calibration and validation intervals while reducing the number of categories, so the model uses the largest size of change while using fewer than the original number of categories.