Our study shows that some but not all computer programs for the interpretation of ECGs perform almost as well as cardiologists in identifying seven major cardiac disorders.

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To allow an exchange of measurements and criteria between different electrocardiographic (ECG) computer programs, an international cooperative project has been initiated aimed at standardization of computer-derived ECG measurements. To this end an ECG reference library of 250 ECGs with selected abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T waves. This task was performed by a group of cardiologists on highly amplified, selected complexes from the library of ECGs. With use of a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained that proved to be highly reproducible and precise. This reference data base was used to study measurement results obtained with nine vectorcardiographic and 10 standard 12-lead ECG analysis programs. The medians of program determinations of P, QRS, and T wave onsets and offsets were close to the final referee estimates. However, an important variability could be demonstrated between measurements from individual programs and mean differences from the referee estimates amounted to 10 msec for QRS for certain programs. In addition, the variances of all programs with respect to the referee point estimates were variable. Some programs proved to be more accurate and stable when the data from high-vs low-noise recordings were analyzed. Average Q wave durations calculated from ECGs for which programs agreed on the presence of a Q or QS wave differed by more than 8 msec in several program-to-program comparisons. Such differences may have important consequences with respect to diagnostic performance. Various factors that might explain these differences have been determined. The present study demonstrates that to allow an exchange of results and diagnostic criteria between different ECG computer programs, definitions, minimum wave requirements, and measurement procedures urgently need to be standardized.Circulation 71, No. 3, 523-534, 1985. DURING the last decade rapid growth has occurred in computer electrocardiographic (ECG) processing.1-3 At present, however, no standards for quantitative ECG analysis exist. There is a lack of agreement on The authors academic affiliations are listed in the Common Standards for Quantitative Electrocardiography (CSE) organizational structure that appears before the references.

In an effort to standardize and evaluate the performance of electrocardiographic computer measurement programs, a 15 lead reference library has been developed based on simultaneously recorded standard 12 lead and orthogonal XYZ lead data. A set of 250 electrocardiograms (ECGs) with selected abnormalities was analyzed by a group of five referee cardiologists and 11 different 12 lead and 6 XYZ computer programs. Attention was focused on the exact determination of the onsets and offsets of P, QRS and T waves. The referees performed their task on highly amplified, selected complexes from the library in a two round process. Median results of the referees coincided best with the median derived from all programs. An analysis of stability proved that the combined program median was a robust reference. However, some individual program results were widely divergent. Paired t tests demonstrated earlier onset for P and QRS (p less than 0.001), as well as later offset for P and T waves in the median 12 lead than in the XYZ results. Significant differences also existed among results obtained by programs analyzing all standard ECG leads at one time, the so-called multilead programs, and those obtained by the conventional standard three lead analysis programs. As a consequence, the derived P, PR, QRS and QT interval measurements varied quite widely among the various programs. Significant differences were also observed among measurements of Q, R and S duration. Some programs showed Q waves that were on the average 6 ms (p less than 0.001) longer than those of others. This may significantly influence diagnostic performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Fretting wear resulting from micro-displacement oscillatory movements is considered a serious impediment to many industrial applications like gears, turbo engines, etc. Large conformal contact configurations of industrial components are very complicated to reproduce at laboratory scale. As a result, simple non-conformal contact geometries including sphere-on-flat and cylinder-on-flat are usually adopted in research laboratories. Yet, few are the researches that examined fretting wear using flat-on-flat geometry due to its high sensitivity to alignment issues although this contact configuration allows the analysis of quasi-constant pressure condition. In the current study, fretting wear of flat-on-flat dry contact made of a steel alloy (35NCD16) is investigated experimentally by varying several parameters including test duration, contact pressure, sliding amplitude and frequency. A power law formulation is introduced providing reliable prediction of the wear rate. The analysis of test results confirms a high dependency of the wear kinetics on the loading condition regarding the transition from abrasive to adhesive wear.

This paper aims at modelling contact oxygenation concept (COC) which describes the effects of fretting loading conditions on di-oxygen flow within the interface and the associated partition between abrasive and adhesive wear domains in fretting wear scars. This is achieved by modelling oxygen transport within fretting interface using an advection-dispersion-reaction approach (ADR) by considering debris bed as a compact porous medium traversed by atmospheric gases. ADR model is calibrated using three fretting tests of flat-on-flat 34NiCrMo16 interface. Results show that ADR approach can predict the partition of abrasion and adhesion for wide range of sliding frequencies, normal forces and contact sizes. Besides, it can capture the transition of wear mechanisms from pure abrasive to mixed abrasive-adhesive wear at different loading conditions.

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