Determination Of Physical Quantities Research Articles

Fischerella sp. biomass measurement by using graphite electrodes

For several decades, the electrical admittance has been very useful for the determination of physical quantities, such as the characterization of some electrical properties of interest in organic samples. In this work, an electrical system based on graphite electrodes to determine the amount of living biomass of the cyanobacteria Fischerella sp. is proposed. Cyanobacteria are phototrophic microorganisms with applications on bioremediation, pharmaceutics, medicine, among others. The strain was characterized in BG-11 medium and cultured at different biomass concentrations. Samples were evaluated by electrical admittance and contrasted by the technique of dry weight in order to correlate the results registered by the/a proposal electric circuit. Scanning frequencies from admittance went in an order from 10 Hz to 1 000 000 Hz. Also, they showed a reproducibility, getting deviations of 6.45 × 10-5. This electrical system can be used to evaluate Fischerella sp. living biomass concentrations with high reliability.

Focus system sensor characterisation by mechanistic-empirical modelling

Focus system sensor characterisation involves the determination of physical quantities from experiment. Herewith an experimental model will need to specify how the sensor is expected to respond to input data and the quality of information obtained depends directly on the performance of the model. With this concern novel model building and solving techniques have been created for sensor comprehensive characterisation. These techniques incorporate a priori knowledge-based approach in mechanistic model elaboration and for attainment the enhanced level of adequacy, accuracy, and precision carry out the approximation of the exact unknown model simultaneously by available mechanistic and polynomial empirical functions. Two different approaches for mechanistic-empirical model solving have been fashioned. These techniques allow the achievement of the high degree of completeness in elaborated models. From models’ validation it has been found that the novel techniques in comparison with pure empirical modelling permit to attain less discrepancy to empirical evidence for the whole region of interest for concerned explanatory variables.

Analytical structure of steady radiative shocks in magnetic cataclysmic variables

In this paper we study specific classes of radiating shocks which are widely spread in astrophysical environments. We present new analytical solutions available for any exponents of typical power-law cooling function which generalize the five special cases (corresponding to specific values of these exponents) of radiating shocks structure and proceed to the analytical determination of physical quantities. Then an application of the results for the accretion shock in polar is realized. A discussion of the reproducibility of cooling layer in laboratory is proposed using scaling laws.

Temperature measurements according to the International Temperature Scale of 1990 and its associated uncertainties

The measurement of temperatures accompanies almost every determination of physical quantities or material properties. This paper gives an outline of the concept of the traceability of temperature measurements according to the International Temperature Scale of 1990 (ITS-90) and the determination of measurement uncertainties. Furthermore, differences between ITS-90 and thermodynamic temperatures are discussed.

Mechanistic-statistical concurrent modelling techniques

Measurements involve the determination of physical quantities by experiment. In this endeavour, an experimental model will need to specify how measurement system is expected to respond to input data, which is the key to extracting information from the system. The quality of information depends directly on the quality of the model. With this concern novel techniques for model quality improvement have been fashioned. For attaining a high level of comprehensiveness, accuracy and precision, the exact unknown model was approximated simultaneously by available mechanistic and appropriate empirical functions. Adequate modelling was accomplished by employing theoretical and empirical data integration. Herewith, additive and multiplicative approaches were elaborated. The application of developed techniques for sensor model perfection has shown that concurrent multiplicative modelling, in comparison with pure statistical modelling, permits the attainment of less discrepancy in experimental evidence for the whole region of interest for model input variables.

Abelian Projection without Ambiguities

Laplacian Abelian Projection is discussed. This term refers to the use of a new (``Laplacian'') gauge fixing prescription for implementing the Abelian Projection of QCD. The gauge condition is based on the lowest-lying eigenvector of the covariant Laplacian operator in the adjoint representation. This Laplacian gauge fixing procedure is free of the ambiguities which plague lattice simulations which work with the popular Maximally Abelian Gauge. Furthermore, Laplacian gauge fixed configurations enjoy a natural kind of smoothness. These two properties are crucial for a reliable determination of physical quantities using the Abelian Projection. We also examine a new, Higgs-field-like observable which emerges as a by-product of the method. This quantity can be used to identify magnetic monopoles in a way independent of the traditional prescription. It is argued that physically relevant magnetic monopoles are accomodated well by the Laplacian method, while they are suppressed (too) strongly in Maximally Abelian Gauge. Finally, first evidence of abelian dominance in the Laplacian Abelian Projection is presented.

Determination of Physical Parameters for Dynamical Processes

Abstract The unknown parameters of physical laws governing the dynamics of processes can be gained from measured input and output-signals in a two-step procedure. First the parameters of differential equations are estimated from measured data and then the physical parameters are calculated based on algebraic relations. This contribution describes theoretical the basics of this method and shows its efficiency in a technical application. Starting with some considerations about the input/output-model structures, the determination of physical parameters from differential equation parameters based on knowledge from theoretical modeling is discussed. Criteria for the identifiability of physical parameters from estimated differential equation parameters and for the sensitivity of the obtained results are given. Finally the determination of physical quantities of an electromechanical drive is demonstrated based on experimental results.

Modelling of Light Polarization Measurement

Abstract A model of light polarization measurement given by a general algorithm formed at the aim of coherency matrix formalism of electromagnetic wave is reported. There are shown the operations needed for measurement of any polarization state and control of measurement process at determination of physical quantities by means of polarization parameters.