Seen from Siena

The article discusses a series of paintings, on a vision of a modern city, inspired by the author’s recent visit to Siena, Italy. It describes an importance of architectural visions and its complementary role in relation to an architectural practice. The article presents the author’s experiences with the process of painting. It highlights the role of a quick sketch in the process of selecting and analysing a subject. Finally, it showsthe unique importance of traditional painting techniques in a realization of the subject, impossible to be replaced by a digital visualization

Effects of good government

The following article describes Ambrogio Lorenzetti’s fresco, Effects of Good Government, introduces the artist and the period when he worked. The author also describes his own artistic experiences in relation to the fresco

Cryptographically Strong Elliptic Curves of Prime Order

The purpose of this paper is to generate cryptographically strong elliptic curves over prime fields Fp, where p is a Mersenne prime, one of the special primes or a random prime. We search for elliptic curves which orders are also prime numbers. The cryptographically strong elliptic curves are those for which the discrete logarithm problem is computationally hard. The required mathematical conditions are formulated in terms of parameters characterizing the elliptic curves.We present an algorithm to generate such curves. Examples of elliptic curves of prime order are generated with Magma

Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses

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Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses

Demand for organic foods is partially driven by consumers' perceptions that they are more nutritious. However, scientific opinion is divided on whether there are significant nutritional differences between organic and non-organic foods, and two recent reviews have concluded that there are no differences. In the present study, we carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods. Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95% CI 5, 33)%, 69 (95% CI 13, 125)%, 28 (95% CI 12, 44)%, 26 (95% CI 3, 48)%, 50 (95% CI 28, 72)% and 51 (95% CI 17, 86)% higher, respectively. Many of these compounds have previously been linked to a reduced risk of chronic diseases, including CVD and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies. Additionally, the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cd. Significant differences were also detected for some other (e.g. minerals and vitamins) compounds. There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems. In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production season

Supply asymmetry of pm motor as a vibration source – diagnostics based on frequency analysis of own signals

W artykule przedstawiono wpływ asymetrii zasilania silnika ze wzbudzeniem pochodzącym od magnesów trwałych na generację drgań w rozpatrywanej maszynie. W pracy przedstawiono model matematyczny asymetrycznie zasilanej maszyny z magnesami trwałymi oraz wyniki badań laboratoryjnych. Autor przedstawił przebiegi czasowe momentu oraz prądu wraz z analizą częstotliwościową. Dodatkowo przedstawiono przebiegi czasowe prędkości drgań dla symetrycznego oraz asymetrycznego zasilania silnika – zarówno dla biegu jałowego, jak również dla stanu obciążenia. W podsumowaniu przedstawiono również autorskie równanie matematyczne, które stanowi pewnego rodzaju marker dla rozpatrywanego zjawiska. Umożliwia to jego zdiagnozowanie na podstawie analizy częstotliwościowej sygnału własnego. Metoda diagnostyczna bazująca na przedstawionej zależności została opatentowana

Bezczujnikowa diagnostyka drganiowa generatorów z magnesami trwałymi – przykład niewywagi

This paper presents a new vibration diagnostic method designed for diagnose of permanent magnets (PM) generators. Those machines are commonly used in small wind, water systems and electrical vehicles. The described method is very innovative and unique. Specific structural properties of machines excited by permanent magnets are used in this method - electromotive force (EMF) generated due to vibrations. In this article several issues will be discussed: the method genesis, the similarity of permanent magnet machines to vibration sensor, mathematical model, and results of simulation and laboratory tests. The method of determination the technical condition of PM electrical machine basing on its own signals is the subject of patent application.Praca przedstawia zastosowanie wibracyjnej metody diagnostycznej dla generatorów z magnesami trwałymi pracujących w stanach asymetrii obciążenia. Maszyny te są wykorzystywane w małych elektrowniach wiatrowych oraz wodnych. Opisywana metoda jest innowacyjna i unikalna. Wykorzystuje ona specyficzne właściwości konstrukcyjne maszyn z magnesami trwałymi, tj. indukowanie się SEM pod wpływem wibracji. W pracy przedstawiono min. podobieństwo maszyny z magnesami trwałymi do czujnika drgań, zawarto wyniki obliczeń, symulacji oraz badań laboratoryjnych. Metoda ta jest przedmiotem zgłoszenia patentowego

Possibility of using the SEM of PM machine for vibration diagnostics

W artykule zaprezentowano wyniki badań pokazujące możliwość wykorzystania SEM maszyn z magnesami trwałymi do diagnostyki wibracyjnej. Przedstawiono właściwość polegającą na indukowaniu się składowej periodycznej SEM pod wpływem czynników zewnętrznych np. drgań. Opisano wyniki testów przeprowadzonych na stole wibracyjnym. Przedstawiono przebiegi czasowe prędkości drgań, napięć indukowanych wraz z analizą częstotliwościową – zarówno dla maszyny będącej w spoczynku, jak również napędzanej. Przedstawiono częstotliwości odpowiadające konkretnym stanom niepożądanym w maszynie PM, które udało się do tej pory wyselekcjonować autorowi.The results of research which demonstrate the possibility of using SEM of machines with permanent magnets for vibration diagnostics. Specific structural properties of PM machines are used by this method - electromotive force (EMF) generated due to vibrations. The results of tests which were made with use of vibration table was described. The waveforms of vibration velocity, induced voltages and frequency analysis are presented - for both states: machine was at rested and driven. Frequencies corresponding to specific undesirable conditions accruing in the PM machine, which the author has been able to select so far, are presented