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This article seeks to show that, although factor analysis (mostly in its exploratory version) is a method frequently applied by social-science researchers (it is often also discussed in basic data analysis textbooks), only a very basic version of it is used, with settings that are far from optimal. However, what settings are used can have major implications, primarily in the form of conceptual problems, where the exploratory version is often used instead of the confirmatory version. Other settings used can also have an impact on the results. These are mainly partial options, which are used mainly in the exploratory version, in particular the choice of the correct correlation coefficients, the choice of method for the initial extraction of factors, the choice of the rotation method and the choice of the number of factors with which we want to work in the exploratory version. The text discusses the algorithms for ordinal variables, and the possibility of determining the number of factors through parallel analysis or MAP. The practical example discusses the advantages of the oblique rotation of factors. The article seeks to highlight good practices that best reflect the current state of the art of quantitative methodology and statistics. In addition to the general guidelines, the article contains practical advice about software and recommends a procedural schema for using factor analysis.
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Statistics is an important scientific discipline that has an impact on many areas of research. One of the most widely used statistical methods is comparative analysis, which includes a large number of tests. The article focus on selected types of comparative analysis tests with examples of its practical concept and possibilities of use in the implementation of research in the social sphere.
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This study aims to provide clarification on system analysis and the presentation of a system analysis report. The method used is meta-analytical. The conclusion is that the system analysis a) highlights the structure, factors, functions, processes and objectives / goals of the system, b) shows the extent to which the system achieves its objectives, c) whether there are computational tools that provide feedback and feedforvard , e) warns about the negative evolutions in the system and f) leads to the optimization of the presence of the system in variable contexts.
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This paper acknowledges the significance of data saturation in research as a methodological instrument governing the non-negotiable yet highly questioned scientific rigor in research. Therefore, it employs a reflective research-practice based approach to evaluate the importance of data saturation in qualitative research. It draws on context and time-bound first-hand research practices of sampling and collecting quality data using face-to-face, semi-structured interviews with migrant entrepreneurs in London between 2017-2021. This paper shows that data saturation is a complex phenomenon expanding beyond the theoretical rationale experienced as a before, during and after an iterative and reflective process of engaging with the research participants and data (i.e., triangulation of sources, disciplinary traditions, researcher’s experiences and participants’ willingness and readiness to share), which anchors researcher’s decision to resume data collection. This paper employs reflective fieldwork-based practices to demonstrate how saturation is reached in a phenomenological interpretative study. Thus, it contributes to the qualitative research scholarship by addressing the misalignment between theory and practice and bringing a practice-based, triangulated perspective on data saturation.
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Starting from Mumford's concept of the machine, the text combines anthropological, archaeological, historical and philosophical themes to outline the transformation of human beings from the earliest prehistoric epochs to the present day. The trajectory thus set out to trace technological threads in human “nature” ranges from the anthropological concept of shamanism and magic, to the question about the beginning of the technicism of human culture from the perspective of prehistory, to the specific visions of the first robots and artificial intelligence in ancient Greece and their theologically-converted reception in the Age of Enlightenment. The article also includes a brief outline of the essence of technics, going back to the early metal age and having to do with the fusion of technology and mathematics that have taken place then.
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The sum ∑𝑛𝑚ℎ≤𝑥 𝑛𝑚 will be estimated in this paper by using elementary methods. The sum ∑𝑛𝑚ℎ≤𝑥 𝑛𝑚 is a generalization of the divisor problem and it is applied when estimating the number of subgroups of the finite index in crystallographic groups ([1], [2]).
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A phosphating process modified for a high-strength low-alloy (HSLA) steel was performed at various temperatures and influence on the surface properties of the Domex steel covered by manganese phosphate (MnP) was investigated by electrochemical corrosion tests supported by a photo documentation performed by the SEM. Corrosion measurements were performed in 0.1M NaCl solution at 22±2 °C using electrochemical impedance spectroscopy and potentio-dynamic polarisation in order to obtain thermodynamic and kinetic corrosion characteristics and individual elements of equivalent circuits. It is that a temperature of the phosphating process has a very significant effect on protection properties of the created manganese phosphate coating on the Domex steel and needs to be strictly monitored. According to results of corrosion testing and surface morphology observations, the optimal temperature for the phosphating process on the tested Domex steel was chosen.
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Premature failure or damage of parts and components of the oil and gas well piping, as well as pipelines for transport of oil and gas, are generally caused by the simultaneous influence of a large number of technological, metallurgical, structural and exploitation factors. Therefore, the convenient structural solutions, which provide the mechanical safety of parts and integrity of structures, can be realized only through total comprehension of their behavior in various operation regimes. Importance of technical diagnostics for monitoring and state analysis of welded pipes/pipelines in oil industry is considered in this paper. An analysis of causes of the welded pipes failures in exploitation has been performed through use of the fault tree analysis. Based on the suggested structure of a database, regarding the causes of failure, possibilities are presented to set measures for prevention of damage and failure of welded pipes/pipelines and for extension of their service life. A suggestion for improvement of the organizational scheme for monitoring the state and maintenance of welded pipes/pipelines during the exploitation has been made, as well.
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In this work, strength and plastic deformation effect of the dual phase steel are analysed in the static and dynamic conditions. Since the dual phase steel is extensively used in the outer body parts of the automotive vehicles, its dynamic strength and plastic strain energy absorption during the crash are essential. Dynamic strength of the dual phase steel is examined using the pendulum impact hammer tester machine. Spread of the plastic strain during the crash is an important factor for the energy absorption to passive safety, which is examined using the local hardness measurement using the Vickers hardness and local indentation yield strength is calculated using cylindrical indenter and obtained force-depth results are analysed using the Hencky theory for the plane strain indentation. Further, tested samples are observed using scanning electron microscopy for the fracture response after the static and dynamic tests.
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The paper proposes a correction method of the oblique-angle vibration for laser doppler vibrometry. It briefly discusses the key mathematical approach considering the surface of the analysed object to be a reference plane and gives a practical example of the method proper application. The proposed correction method is practically verified by laboratory measurement of natural frequencies and mode shapes for vibrations of high voltage transformer housing. The results are further compared to equivalent accelerometer measurement.
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Impact of applied current density during the plasma electrolytic oxidation (PEO) process on corrosion resistance of AZ31 magnesium alloy was studied. The PEO coatings were prepared using four different current densities with values of 0.025 A/cm2, 0.05 A/cm2, 0.1 A/cm2 and 0.15 A/cm2 in electrolyte consisting of 10 g/l Na 3PO4.12H2O and 1 g/l KOH. Morphology and chemical composition of the coatings was examined using the scanning electron microscopy and EDS analysis respectively. Electrochemical characteristics of ground and coated samples were measured by means of electrochemical impedance spectroscopy (EIS) in 0.1M NaCl solution. Obtained data in form of Nyquist diagrams were analysed by equivalent circuit method. Results of experiments showed that value of applied current density had significant effect on protective performance of the PEO coatings prepared on AZ31 magnesium alloy surface.
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This paper reports the results of the experimentally determined effects of decontaminating agents on metal surfaces resulting from passive and active decontamination after sulphur mustard (Yperite) contamination. The paper includes an analysis of the experimentally obtained results for each metal (Zinc, Nickel, Aluminium, Brass, Steel, Copper).
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Silicon nanocrystalline particles (ncSi) were fabricated from the Si swarf using the beads milling method. Observed photoluminiscence spectra (PL) of the ncSi in hexane with the dimethylanthracene molecules (DMA) show photoluminescence peaks at energies of 2.55, 2.75, 2.92, and 3.09 eV. The shape of PL spectra corresponds to the vibronic structure of adsorbed DMA molecules. The PL intensity of the ncSi-DMA system increases by ~3000 times by adsorption of DMA on Si nanoparticles. The PL enhancement results from an increase in absorption probability of incident light by DMA caused by adsorption on the surface of ncSi. Theoretical model of the PL experiment was constructed and resulting model parameters were used in analysis of possible PL transitions and charge transfer processes.
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The acoustic spectroscopy is used to study properties and changes in structural arrangement in silicone oil based magneto-rheological fluids with carbonyl iron particles upon the effect of an external magnetic field. Attenuation spectra at three temperatures for various concentrations of magnetic particles are presented. The attenuation of acoustic waves was measured for a jump change of the magnetic field to 200 mT as a function of the temperature. The relaxation effects for the acoustic attenuation after switching off the magnetic field and its decrease to the similar value as for clean silicone oil were observed. The change of acoustic attenuation in magneto-rheological fluid versus angle between the wave vector of acoustic waves and direction of the applied magnetic field was measured, too. For the anisotropy measurement are characteristic two local maxima from which results chain orientation in direction of the magnetic field.
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We provide an algorithm for generation of momenta (or energies) of relativistic particles according to the relativistic Bose-Einstein or Fermi-Dirac distributions. The algorithm uses rejection method with effectively selected comparison function so that the acceptance rate of the generated values is always better than 0.9. It might find its use in Monte-Carlo generators of particles from reactions in high-energy physics.
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We investigate how the recent LHC measurements limit the parameters of the hypothetical vector resonance triplet. The vector resonances are assumed to represent bound states of hypothetical strongly-interacting new physics, a candidate of the extension of the Standard model.
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Some biological experiments and techniques, especially electron microscopy, require special sample treatments. These treatments usually change the samples and biologist cannot apply different techniques on the very same sample. In this case, it is necessary to have some comparison method to compare different treatments. In the electron microscopy, the heavy metals are used as contrasting chemicals. Question is which contrasting method is the best or which is better for imaging of given samples. Standard method is based on visual comparison and it is user dependent. We propose to measure local contrast and some other values like SNR (Signal-to-Noise Ratio), histograms, intensity profiles on the borders of the object and calculate statistical values for pixels' intensities.
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The aim of this article is a comparison of the EDFA (Erbium Doped Fibre Amplifier) and the DRA (Distributed Raman Amplifier) in a fully optical communication system, working on a specific wavelength. The amplifiers are compared based on their position in the optical loop and are evaluated according to the Q-factor and bit error rate (BER). In the case of the DRA, the accomplished distance was smaller, while changing the optical power in CW (Continuous Wave) to attain better BER. In the application of the EDFA a similar optical loop was created, as well, while the basic parameter for comparison was a bit speed. For the EDFA the bit speed was changed from 10 to 15 Gbps. For the DRA the change was in the power from 1 to 3 mW with the bit speed kept at 10 Gbps. This publication also focuses on the need for such application of a transfer system in a software environment. It would enable examination and research and consequently a minimising of the influence of non-linear effects impacting the particular WDM (Wavelength Division Multiplex) system.
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