Search results for "reliability"
showing 10 items of 1563 documents
Utilisation of barium-modified analcime in sulphate removal: Isotherms, kinetics and thermodynamics studies
2017
Abstract Analcime and commercial zeolite were employed as a precursor for preparing sorbent material for SO42− removal over barium modification. Three sorbents were prepared: barium-modified analcime (ANA-Na-Ba), barium-modified acid-washed analcime (ANA-Ac-Na-Ba) and barium-modified zeolite (ZSM5-Na-Ba). Of the prepared materials, ANA-Ac-Na-Ba was the most efficient sorbent material for SO42− removal, with a maximum sorption uptake of 13.7 mg g−1 at room temperature. Batch sorption experiments were performed to evaluate the effect of initial pH, initial SO42− concentration, sorbent dosage, temperature and contact time of sorption. Several isotherms were applied to describe the experimental…
Sound and reusable components for abstract interpretation
2019
Abstract interpretation is a methodology for defining sound static analysis. Yet, building sound static analyses for modern programming languages is difficult, because these static analyses need to combine sophisticated abstractions for values, environments, stores, etc. However, static analyses often tightly couple these abstractions in the implementation, which not only complicates the implementation, but also makes it hard to decide which parts of the analyses can be proven sound independently from each other. Furthermore, this coupling makes it hard to combine soundness lemmas for parts of the analysis to a soundness proof of the complete analysis. To solve this problem, we propose to c…
Data repeatability and acquisition techniques for Time-Domain Spectral Induced Polarization
2013
The Time Domain Induced Polarization (TDIP) technique is widely used in applied geophysics, particularly for environmental issues, for instance for delineating landfills or detecting leachate percolation. Because the reliability of IP data remains an issue at the field scale, this paper deals with the factors controlling data quality and compares different arrays and acquisition parameters for optimal collection of data in the field. The first part focuses on repeatability experiments carried out in the former Horlokke landfill (Denmark), in order to infer the degree of which a signal can be reproduced over time. Results show a good repeatability, with on average less than 10% of difference…
The Multivariate Individual Selection of Diagnostic Tests and the Reserved Diagnostic Statement: An Optimum Combination of Two New Methods for the Co…
1984
A combination of two new methods for the diagnostic procedure in computer-aided differential diagnosis is presented. It is constructed on the basis of new results of our own in the field of mathematical decision theory and is demonstrated by the differential diagnosis of congenital heart diseases by means of ECG features.
Probabilistic analysis of truss structures with uncertain parameters (virtual distortion method approach)
2004
A new approach for probabilistic characterization of linear elastic redundant trusses with uncertainty on the various members subjected to deterministic loads acting on the nodes of the structure is presented. The method is based on the simple observation that variations of structural parameters are equivalent to superimposed strains on a reference structure depending on the axial forces on the elastic modulus of the original structure as well as on the uncertainty (virtual distortion method approach). Superposition principle may be applied to separate contribution to mechanical response due to external loads and parameter variations. Statically determinate trusses dealt with the proposed m…
Atypical transistor-based chaotic oscillators: Design, realization, and diversity
2017
In this paper, we show that novel autonomous chaotic oscillators based on one or two bipolar junction transistors and a limited number of passive components can be obtained via random search with suitable heuristics. Chaos is a pervasive occurrence in these circuits, particularly after manual adjustment of a variable resistor placed in series with the supply voltage source. Following this approach, 49 unique circuits generating chaotic signals when physically realized were designed, representing the largest collection of circuits of this kind to date. These circuits are atypical as they do not trivially map onto known topologies or variations thereof. They feature diverse spectra and predom…
Testing equality of reliability and stability with simple linear constraints in multi-wave, multi-variable models
1998
Data from a longitudinal study on school achievement were used to develop new methods for analysing reliability of measurements and stability of behaviour over a long time interval. The proposed method of analysis makes it possible to test hypotheses about equality constraints on reliability and stability. It is known that the use of negative variances for imaginary latent variables with equality constraints between structural parameters produces standardized variances for endogenous latent variables and quality constraints for coefficients of stability. Reparameterization of random errors in measurement models allows equality constraints to be set for coefficients of cross-sectional and of…
Dynamic behaviour of cracked granite and marble columns retrofitted with steel collars
2014
Marble and heavy stone columns are widely diffused in ancient churches and historical buildings in all the Mediterranean area. Their good mechanical properties allowed carrying great load values, while their bright colours and aesthetical characteristics have been used by a lot of ancient architects to achieve structural solutions with great visual impact. Despite their good compressive strength, marble columns could be damaged from environmental effects (e.g. longterm effects or thermal loads), which could crack the structural members. In this way, the slenderness of the column increases drastically and the presence of an imposed ground shaking could be critical, since the column will be m…
Digital generation of multivariate wind field processes
2001
Abstract A very efficient procedure for the generation of multivariate wind velocity stochastic processes by wave superposition as well as autoregressive time series is proposed in this paper. The procedure starts by decomposing the wind velocity field into a summation of fully coherent independent vector processes using the frequency dependent eigenvectors of the Power Spectral Density matrix. It is shown that the application of the method allows to show some very interesting physical properties that allow to reduce drastically the computational effort. Moreover, using a standard finite element procedure for approximating the frequency dependent eigenvectors, the generation procedure requi…
Reliability of physical functioning measures in ambulatory subjects with MS.
2005
Background and Purpose. One of the primary reasons for measuring outcomes during rehabilitation is to determine the effect of physiotherapy. Repeated measurement situations are susceptible to several sources of error, including inconsistencies caused by the subject, the procedure, the instrument and the examiner. Therefore, the reliability of the measures needs to be examined. Method. The present study used a repeated-measures design. Two studies were undertaken to examine the test–retest and inter-rater reliability for physical functioning measures. The interval between the measurements was one week. The sample consisted of 19 ambulatory subjects with mutliple sclerosis (MS) in the test–re…