The 50 most-cited articles in Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu, 2017

Optica Applicata, Vol. 47, 2017, nr 2, s. 183-198

Kinetic models can be used to characterize the flotation process.In this paper, three primary parameters, namely, distribution of flotation rate constant f(K), order of flotation process n and ultimate recovery R ∞ are presented to perform analysis of flotation kinetics.The flotation rate constant f(K) is a function of both the size and hydrophobicity of particles.Though the more commonly used distributions are Delta function as well as Rectangular, Kelsall and Gamma models, there is no agreement in the literature as to which distribution function better characterize the floatability distribution.The first-order models can be used to describe most mineral flotation processes, while there is also evidence that the nonintegral-order equation is capable of representing the kinetic characteristics of the batch flotation process.The order is lower than 1 in the initial moments of the flotation process.The solution of ultimate recovery calculated by the least squares method is greater than 100% (R ∞ >100%).An empirical model was proposed to avoid the improper phenomenon in the solution of…

Several sinkhole collapses were occurred in the many sites in urban areas and/or their rural periphery; in NE Algeria, in the last few years.The abrupt collapse causes damages to properties, infrastructures, and even lives.The most spectacular oneoccurred in February 2009 inside the Cheria city, Northwest of Tebessa department, with a diameter of more than a hundred meters.This abrupt collapse is due to a sudden rupture of the roof of a large underground karst cavity.It caused panic-stricken among the population living near the crater.In order to investigate the origin of this phenomenon, we combine several geophysical and geotechnical methods, such as Ground Penetrating Radar, Electrical Resistivity Tomography, Standard Penetration Test, Mechanical Drill Core, Cave Survey Photogrammetry, etc.It appears that each method may provide specific information.Their comparison allows to precise the results itself, the limits and the application field of each.Consequently a number of open karst voids and disturbed areas were detected in the study area.The results show that sinkholes…

Optica Applicata, Vol. 47, 2017, nr 4, s. 557-578

The Bond work index is a measure of ore resistance to crushing and grinding and is determined using the Bond grindability test. Its value constitutes ore characteristic and is used for industrial comminution plants designing. Determining the Bond work index value is quite complicated, time-consuming and requires trained operating personnel and therefore is subjected to errors. A quick method for the Bond work index approximate value determination, which is based on the first order grinding kinetics, is presented in this paper. Comparative experiments for the Bond work index value determination using the standard and quick procedures were carried out on samples of limestone and andesite, and on composite samples containing both ores in different mass proportions. This quick procedure can be performed with an arbitrary number of milling cycles, depending on the desired accuracy.

Optica Applicata, Vol. 47, 2017, nr 3, s. 421-433

Professional skepticism is an essential concept in auditing practice and theory.It has been identified in almost all existing auditing standards, however, the way it should be characterized is still unclear.Both researchers and regulators emphasize the importance of the concept but struggle on how to define and measure it.It is also often difficult to indicate if the lack of skepticism is the primary cause of audit deficiencies and what factors led to the lack of skepticism.The purpose of this paper is to synthesize research related to auditors' professional skepticism and indicate major characteristics of such an attitude.I organize research studies into six categories related to attributes that a skeptic should possess: a questioning mind, a suspension of judgment, a search for knowledge, interpersonal understanding, self-esteem, and autonomy.These research findings have implications for practice and regulations (standards), but in order to understand how skeptical judgment translates into skeptical action, additional research will need to be conducted.

Optica Applicata, Vol. 47, 2017, nr 4, s. 635-649

Power Electronics and Drives, Vol. 2 (37), No. 2, 2017, p. 137-150

Streszczenie: W ostatnich latach na rynku pracy zaznacza swoją obecność najmłodsze z pokoleń określane mianem Z, a jego przedstawiciele przyszli na świat po 1994 roku.Czasy, w których przypadło im dorastać, sprawiły, że czują się swobodnie, korzystając z dóbr nowych technologii.W związku z tym formułują wobec pracodawców roszczenia odnośnie do zmiany podejścia do warunków ich zatrudnienia.Zapoznanie się z wymaganiami, aspiracjami i podejściem pokolenia Z do wykonywanej pracy może być przyczynkiem do podjęcia działań ukierunkowanych na zmiany w zakresie konstruowania modelu zaangażowania w wypełnianie obowiązków zawodowych.W pierwszej części artykułu -teoretycznej, dokonano interpretacji pojęcia "pokolenie" oraz charakterystyki najmłodszego pokolenia określanego jako Z. Drugą część niniejszej pracy stanowi prezentacja wyników badania ankietowego.Jego celem było pozyskanie informacji na temat oczekiwań, którymi kierują się przedstawiciele pokolenia Z wobec pracy zawodowej i pracodawców. Słowa kluczowe: pokolenie Z

Search based techniques have been widely applied in the domain of software testing. This Systematic Literature Review aims to present the research carried out in the field of search based approaches applied particularly to mutation testing. During the course of literature review, renowned databases were searched for the relevant publications in the field to include relevant studies up to the year 2014. Few studies for the year 2015--16, gathered by performing snowball search, have also been included. For reviewing the literature in the field, 43 studies were evaluated, out of which 18 studies were thoroughly studied and analysed. The result of this SLR shows that search based techniques were applied to mutation testing primarily for two purposes, either for mutant optimisation or for test case optimisation. The future directions of this SLR suggests the application of search based techniques for other issues related to mutation testing, like, solution to equivalents mutants, generation of non-trivial mutants, multi-objective test data generation and non-functional testing.

Koncepcja wspólnego wykorzystywania zasobów lub dzielenia się nimi nie jest zjawiskiem nowym, jednak rozwój technologii mobilnych i społeczności internetowych spowodował, że wymiana zasobów nabrała zupełnie innego wymiaru i dynamicznie zwiększa się jej skala, obejmując coraz to nowe sektory gospodarowania. Jak większość stosunkowo nowych zjawisk, tak i sharing economy jest różnie definiowane i nie jest ustalone, które formy dzielenia się nazwa ta powinna obejmować, a których nie. W artykule przedstawiono koncepcję sharing economy, scharakteryzowano obszary jej wdrożenia oraz omówiono czynniki wywierające istotny wpływ na jej rozwój. Artykuł ma charakter przeglądowy i powstał na podstawie badań literaturowych

Optica Applicata, Vol. 47, 2017, nr 1, s. 41-49

Froth flotation of copper-zinc-lead ores is a complex process based on similar metallurgy processing and strong interactions between chalcopyrite and sphalerite. These types of ores represent 15% of the world production and 7.5% of copper deposits all over the world. In the present study, an attempt is made to assess the feasibility of froth flotation of a complex sulphide ore, where the effect of liberation grade as well as depressant, collector and frother dosage was studied. Copper flotation is dependent on the mineral liberation grade, which is significantly related with the size distribution. It was shown that longer grinding time increased the Cu grade but decreased the copper recovery due to the presence of very fine particles. Lime and sodium metabisulphite, used as depressants, allowed to achieve a good flotation performance. It was shown that for this type of ore lower dosage of the collector should be applied. Finally, a higher frother dosage led to a greater selectivity and reduced entrainment of very fine particles, but also caused low kinetic ratio and low recovery of…

Optica Applicata, Vol. 47, 2017, nr 1, s. 141-155

Power Electronics and Drives, Vol. 2 (37), No. 2, 2017, p. 49-59