Data Evaluation Procedures Research Articles

Statistical Modelling of CO and NO2 Concentrations in the Athens Area - Evaluation of Emission Abatement Policies (7 pp)

This paper describes a statistical modelling approach, suggested as a policy tool in the Athens area for the assessment of the emissions reduction level required to meet the air quality standards for two criteria air pollutants. More than ten years of hourly CO and NOx-NO2 concentration data measured by the monitoring network of the Hellenic Ministry for the Environment, Physical Planning and Public Works were analyzed and the original dataset has been reduced using a data evaluation procedure. Seasonal pollutant concentration trends suggested that the reduction of CO and NOx concentrations observed in the beginning of the '90s is almost entirely attributed to the increase of the catalyst-equipped cars during this period. The numerical parameters of an empirical model relating EU standard exceedances with mean annual concentrations were defined and the model was validated using datasets from years that were not used for the estimation of these parameters. This model was used in conjunction with a roll-back equation as a policy tool for the assessment of the effect of different CO and NOx emissions reduction scenarios on air quality standard compliance for CO and NO2. Results predicted with this empirical modelling approach were assessed with monitored data averaged over a 3-year period, giving satisfactory results. A methodology suggested for assessing the effects of different emissions reduction scenarios on air quality standard attainment was successfully applied for CO and NO2 in the Athens area. The proposed methodology can provide a useful tool for the evaluation of policies already in progress as well as the development of future policies for emissions reduction in urban areas with similar characteristics, aiming at air quality standard compliance on a timely manner, Such a methodology could be applied in other urban areas of Greece characterized by dense traffic, therefore assisting the development of national policies in relation to air pollutants for which standard exceedances occur.

Modeling of time-resolved laser-induced incandescence transients for particle sizing in high-pressure spray combustion environments: a comparative study

In this study experimental single-pulse, time-resolved laser-induced incandescence (TIRE-LII) signal intensity profiles acquired during transient Diesel combustion events at high pressure were processed. Experiments were performed between 0.6 and 7 MPa using a high-temperature high-pressure constant volume cell and a heavy-duty Diesel engine, respectively. Three currently available LII sub-model functions were investigated in their performance for extracting ensemble mean soot particle diameters using a least-squares fitting routine, and a “quick-fit” interpolation approach, respectively. In the calculations a particle size distribution as well as the temporal and spatial intensity profile of the heating laser was taken into account. For the poorly characterized sample environments of this work, some deficiencies in these state-of-the-art data evaluation procedures were revealed. Depending on the implemented model function, significant differences in the extracted particle size parameters are apparent. We also observe that the obtained “best-fit” size parameters in the fitting procedure are biased by the choice of their respective “first-guess” initial values. This behavior may be caused by the smooth temporal profile of the LII cooling curve, giving rise to shallow local minima on the multi-parameter least squares residuals, surface sampled during the regression analysis procedure. Knowledge of the gas phase temperature of the probed medium is considered important for obtaining unbiased size parameter information from TIRE-LII measurements.

Terms and notations for laser-induced breakdown spectroscopy

A breakdown of the number of publications in the field of laser-induced breakdown spectroscopy (LIBS) since the early 1980s is shown in Fig. 1. These numbers are based on a database query in Chemical Abstracts conducted in February 2006 (terms used for the query: LIBS and laser, excluding abbreviations beginning with the letters LIB. The number of hits depends of course on the selected database and combination of terms used for the query. A more extended query in various databases yields more than 350 publications in the year 2005.). The dynamic growth to more than 150 publications per year reflects an increasing community of contributors, many of them appearing for the first time. Awide variety of terms and notations are used to describe the experimental set-ups, measuring parameters and data evaluation methods which thereby complicates the comparability of the analytical approaches and results. LIBS is an interdisciplinary analytical technique employed by researchers from many academic disciplines ranging from chemistry, physics, material science, geology, archeology and others who have different levels of awareness and understanding of LIBS theory, experimental procedures and data evaluation processes. Without claiming to give a complete terminology or comprehensive list of notations for LIBS, this contribution offers a first step forward towards the improved communication of LIBS data using a base set of defined and unified terms and notations that are recommended for use in scientific publications on LIBS and, therefore, should stimulate a dynamic discussion in the LIBS community. The section “Standardized and established terminology”, summarizes selected terms relevant for LIBS that are already defined in international standards or review articles. It is followed by the section on “Specific terms, notations and symbols for LIBS” which presents a new list of defined terms that are necessary for a definitive description of LIBS experiments and data evaluation procedures.

Non-invasive glucose monitoring in patients with diabetes: A novel system based on impedance spectroscopy

The aim of this work was to evaluate the performance of a novel non-invasive continuous glucose-monitoring system based on impedance spectroscopy (IS) in patients with diabetes. Ten patients with type 1 diabetes (mean+/-S.D., age 28+/-8 years, BMI 24.2+/-3.2 kg/m(2) and HbA(1C) 7.3+/-1.6%) and five with type 2 diabetes (age 61+/-8 years, BMI 27.5+/-3.2 kg/m(2) and HbA(1C) 8.3+/-1.8%) took part in this study, which comprised a glucose clamp experiment followed by a 7-day outpatient evaluation. The measurements obtained by the NI-CGMD and the reference blood glucose-measuring techniques were evaluated using retrospective data evaluation procedures. Under less controlled outpatient conditions a correlation coefficient of r=0.640 and a standard error of prediction (SEP) of 45 mg dl(-1) with a total of 590 paired glucose measurements was found (versus r=0.926 and a SEP of 26 mg dl(-1) under controlled conditions). Clark error grid analyses (EGA) showed 56% of all values in zone A, 37% in B and 7% in C-E. In conclusion, these results indicate that IS in the used technical setting allows retrospective, continuous and truly non-invasive glucose monitoring under defined conditions for patients with diabetes. Technical advances and developments are needed to expand on this concept to bring the results from the outpatient study closer to those in the experimental section of the study. Further studies will not only help to evaluate the performance and limitations of using such a technique for non non-invasive glucose monitoring but also help to verify technical extensions towards a IS-based concept that offers improved performance under real life operating conditions.

Nondestructive detection of fatigue damage in austenitic stainless steel by positron annihilation

Austenitic stainless steel specimens have been examined by positron-lifetime measurements at various stages until failure during fatigue tests at constant stress or plastic strain amplitudes. A positron-source-detector assembly has been mounted on the servohydraulic testing machines that allowed truly non-destructive positron annihilation studies without removing the specimens from the load train. Positrons were generated by a 72Se/72 As source with a maximum activity of 0.9 MBq (25 μCi). The average positron lifetime has been determined by a β+ − γ-coincidence applying a simplified data evaluation procedure. Under constant stress or plastic strain amplitudes early stages of fatigue damage could be detected. The strong increase of the average positron lifetime already during the first 10% of fatigue life could be related to the fatigue life of the specimens. Issues of lifetime prediction by positron annihilation measurements are discussed.

Evaluation of 233Pa decay data

An evaluation of the complete scheme and data for 233Pa decay, including results of the recent measurements, is presented. Several data evaluation procedures were used in the analysis of the half-life data. The half-life has been determined to be 26.971±0.013 days. All the gamma-ray emission probabilities ever published have been examined, and the gamma-ray emission probability for the reference 312-keV γ line is recommended as 38.35±0.28%. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. Other decay characteristics have been calculated using the ENSDF analysis program. Finally, a new 233Pa decay scheme has been built.

Isotope amount ratio measurements by ICP-MS: aspects of software induced measurement bias and non-linearity

The effect of a post-acquisition software induced bias on the measurement of the 235U/238U isotope amount ratio in the reference material IRMM-184 was studied. The total uranium concentration ranged from 7 to 2500 pg g−1 [80 (235U) to 3500000 (238U) counts per second], thus covering the entire pulse counting range of the ICP-MS instrument. The bias for the measured ratio increases with decreasing count rate, and it is mostly governed by the count rate of the 235U isotope. Blocking the data into large subgroups is one way of reducing the effects of the bias; however, a decreased number of blocks is accompanied by an increased scattering of the standard uncertainty. Using a more laborious, manual data evaluation procedure of a less processed raw measurement signal not only solves the problem, it also increases the linear measurement range by at least ten times. At the lowest concentration, 7 pg g−1 total uranium concentration, the combined uncertainty of the observed ratio was less than 5% (k = 2).

Pushing the Precision Limit of 14C AMS

High precision for radiocarbon cannot be reached without profound insight into the various sources of uncertainty which only can be obtained from systematic investigations. In this paper, we present a whole series of investigations where in some cases 16O:17O:18O served as a substitute for 12C:13C:14C. This circumvents the disadvantages of event counting, providing more precise results in a much shorter time. As expected, not a single effect but a combination of many effects of similar importance were found to be limiting the precision.We will discuss the influence of machine tuning and stability, isotope fractionation, beam current, space charge effects, sputter target geometry, and cratering. Refined measurement and data evaluation procedures allow one to overcome several of these limitations. Systematic measurements on FIRI-D wood show that a measurement precision of ±20 14C yr (1 σ) can be achieved for single-sputter targets.

Selection and Evaluation of Test Data Based on Genetic Programming

In the literature, we find several criteria that consider different aspects of the program to guide the testing, a fundamental activity for software quality assurance. They address two important questions: how to select test cases to reveal as many fault as possible and how to evaluate a test set T and end the test. Fault-based criteria, such as mutation testing, use mutation operators to generate alternatives for the program P being tested. The goal is to derive test cases capable of producing different behaviors in P and its alternatives. However, this approach usually does not allow the test of interaction between faults since the alternative differs from P by a simple modification. This work explores the use of Genetic Programming (GP), a field of Evolutionary Computation, to derive alternatives for testing P and introduces two GP-based procedures for selection and evaluation of test data. The procedures are related to the above questions, usually addressed by most testing criteria and tools. A tool, named GPTesT, is described and results from an experiment using this tool are also presented. The results show the applicability of our approach and allow comparison with mutation testing.

Accurate determination of liquid viscosity and surface tension using surface light scattering (SLS): Toluene under saturation conditions between 260 and 380 K

Earlier reported values of the liquid kinematic viscosity and surface tension of the reference fluid toluene between 263 and 383 K under saturation conditions from surface light scattering have been recalculated. For this, an improved data evaluation scheme based on an exact description of the hydrodynamic capillary wave problem for a liquid-vapor interface has been applied. The maximum adjustments amount to 0.9 and 0.6% for the liquid kinematic viscosity and surface tension, respectively. These changes are within the uncertainties as stated in our original work which demonstrates that for the surface light scattering technique a total uncertainty of better than 1.0% for both properties of interest also holds for the revised data of the present work. Thus, in spite of the additional complexity connected with this very precise data evaluation procedure presented here, the surface light scattering technique could still be used with less complexity for a reliable determination of surface tension and liquid kinematic viscosity with an accuracy comparable or even better than that of conventional methods. While almost all of these conventional methods determine viscosity and surface tension in a relative manner with two completely different sets of experimental equipment, for the surface light scattering technique no calibration procedure is needed and both properties can be determined simultaneously without any extra effort.

Introduction to interpretation of stochastic parameters: Computer‐intensive procedures for evaluation of data in enzyme kinetics

AbstractComputer simulation of a simple enzyme kinetic model is used to train medical students in interpretation of the stochastic nature of experimentally estimated model parameters. The principles for identification of parameters and estimation of their confidence intervals with the help of Monte Carlo procedures are introduced in a simplified and easily perceivable form.

Development of a Multi-nutrient Data Quality Evaluation System

The U.S. Department of Agriculture's (USDA) Nutrient Data Laboratory (NDL) has redesigned the software of the USDA Nutrient Databank to provide a system for data acquisition, compilation, and dissemination, and as part of this system has developed a module to facilitate the evaluation of analytical data quality. USDA's first data evaluation procedures were developed as a manual system to assess the quality of analytical data for iron, selenium and carotenoids in foods. These procedures have been modified and expanded for multi-nutrient data quality evaluation. The same five evaluation categories; sampling plan, number of samples, sample handling, analytical method and analytical quality control, from the original work have been maintained but the evaluation questions have been made more objective. The rating scales for each category have been changed from discrete steps to a more continuous scale. These ratings are combined to give a Quality Index (QI), and Confidence Code (CC) that is disseminated with the nutrient data to indicate the level of confidence in the value. The algorithm for combining ratings from the five categories was revised from earlier systems to avoid the possibility that the aggregation of several mediocre data points would together, merit the highest CC.

A portable electronic nose based on embedded PC technology and GNU/Linux: hardware, software and applications

This paper describes a portable electronic nose based on embedded PC technology. The instrument combines a small footprint with the versatility offered by embedded technology in terms of software development and digital communications services. A summary of the proposed hardware and software solutions is provided with an emphasis on data processing. Data evaluation procedures available in the instrument include automatic feature selection by means of SFFS, feature extraction with linear discriminant analysis (LDA) and principal component analysis (PCA), multi-component analysis with partial least squares (PLS) and classification through k-NN and Gaussian mixture models. In terms of instrumentation, the instrument makes use of temperature modulation to improve the selectivity of commercial metal oxide gas sensors. Field applications of the instrument, including experimental results, are also presented.

Development of marine water quality criteria for the USA

The US Environmental Protection Agency has developed guidelines for deriving numerical national water quality criteria for the protection of aquatic organisms and their uses. These guidelines provide the method for deriving water quality criteria, including minimum data base requirements, data evaluation procedures, and calculations. The guidelines have been in place for a long time, and states have used them to derive water quality standards for their water bodies. More recent efforts have been directed towards the development of technical guidance based on the concept that bioassessment and biocriteria programs for estuaries and near coastal waters are interrelated and are critical components of comprehensive water resource protection and management. This is a holistic approach to protection and management, integrating biological assessments into traditional chemical and physical evaluations and augmenting the established water quality criteria. The method for deriving water quality criteria and the approach for biocriteria development for marine systems are described.

Simultaneous ICP atomic emission spectrometry for accurate stoichiometric determination: application to a YNi2B2C superconducting material system

For characterisation of the exact stoichiometry of semiconductor or superconductor compounds, the determination of major components with high precision and accuracy is necessary. In order to assess ICP-AES for this task, sophisticated procedures for sample preparation, measurement optimisation and data correction and evaluation, such as multi-line measurements for each analyte element, optimum calibration and recalibration, and internal standardisation, have been developed for simultaneous Echelle spectrometers with CID or CCD detectors. Procedures and results are demonstrated for superconducting materials of the YNi2B2C type. For the analyte elements Y, Ni and B, as well as for the internal standard element In, three optimum spectral lines were used. Calibration and external standardisation were carried out using different mixtures of mono-elemental standard solutions. The confidence intervals for the determination of Y, Ni and B were lowered to 0.17, 0.11 and 0.13% (w/w), respectively. Thus, the stoichiometric coefficients were determined with an error smaller than 0.002, 0.002 and 0.003 for Y, Ni and B, respectively. Using the F-test, the sample homogeneity was tested and, in this way, the presence of trace amounts of secondary phases were detected.

Data evaluation procedure for high-resolution neutron diffraction methods

An evaluation procedure for high-resolution powder neutron diffraction data was developed for determination of microstructural parameters, such as a lattice strain, microstrain, crystallite size and/or distribution of the interplanar spacing from sin

A small volume spherical resonator method for the acousticalspectrometry of liquids down to audio frequencies

A method for measuring the acoustical attenuation coefficient ofliquids in the frequency range 12.5-150 kHz is described. Details of theeasy-to-obtain spherical resonator cells with comparatively small samplevolume (⩽1 l) are shown and a favourable measuring procedure ispresented. Particular attention is paid to the resonator transfer function,including higher order vibration modes. Possible sources of error arediscussed and a procedure for an adequate evaluation of data is given.The usability of the method is illustrated by reference measurements onaqueous solutions of manganese sulphate and of the monosaccharide D-fructose.

A high frequency shear wave impedance spectrometer for low viscosityliquids

A method for measuring the complex shear viscosity spectra of lowviscosity liquids in the frequency range 6-120 MHz is described. Details ofthe resonator cell, based on a thickness shear (AT-cut) quartz resonator as central device, andof the RF bridge circuit for the compensation of the unloaded capacitance ofthe resonator are presented. A measuring and data-evaluation procedure thatallows the careful consideration of spurious higher order vibration modes andalso of intrinsic cell losses is discussed. Sources of experimental error areshown and the usability of the method is illustrated by referencemeasurements. The complex viscosity spectrum of n-dodecanol is displayed andits relaxation frequency is compared with the value resulting from broad-bandacoustical attenuation spectrometry.

Conformation of Polymer Brushes at Aqueous Surfaces Determined with X-ray and Neutron Reflectometry. 1. Novel Data Evaluation Procedure for Polymers at Interfaces

We present a new data refinement technique for the evaluation of X-ray and neutron reflectometry measurements of interface layers comprising linear molecules. The new method is particularly well-suited-but not limited to-modeling the structure of surface-grafted linear polymers organized in polymer brushes. In this paper, we discuss technical details of the data inversion technique and demonstrate its capabilities by recovering the structure of a simulated molecular ensemble for which synthetic data sets have been constructed. In the following paper, we utilize this machinery to reveal the nature of a phase transition pertinent to surface-anchored lipopolymers at high molecular densities.

Intranet in Baden-Württemberg (Germany) – using the technology of the Internet for internal information interchange within a State Plant Protection Service

This article describes the new possibilities of an intranet for internal interchange of information within the plant protection service of a German federal state. In Baden-Wurttemberg, the precondition is a closed internal network with central information servers and workstations at the local offices of agriculture. The intranet with information servers is based on the technology of the Internet and is a modern and user-friendly tool for supplying advisers highly efficiently and economically with current comments, relevant notices, files, weather data and evalutions of computer aids for decision-making. In the last 2 years, significant progress has been made in the automation of procedures for data request, transmission and evaluation of weather data for the warning service. In the plant protection service of Baden-Wurttemberg, the most important data-processing routines and evaluations of computer aids for decision-making are running automatically as batch files. In order to save time in the preparation of regional warnings, the relevant information is available to the advisers via intranet at the beginning of their work. Compared with traditional procedures, the intranet with information servers is advantageous to the information supplier (Central Institute of Plant Protection) as well as to the user (advisers at the local offices of agriculture).