Determination of activation energy of the pellets and sawdust using thermal analysis

ArticleThe aim of this study is to describe the thermophysical properties of pellets and sawdust. Samples were chosen with regard to sustainability and environmental friendliness of materials. The main object of this paper was the investigation of thermal degradation of selected samples. Industrial pellets from Slovakia and sawdust from household source were compared. Materials suitable for pyrolysis are organic materials that degrade at increased temperature. Cellulose, hemicellulose and lignin are main components of biomass (wood) in varying proportions. Thermal processes were carried out from 25 °C to 850 °C using inert nitrogen atmosphere. Heating rate was linear from 5 °C min-1, 10 °C min-1 to 20 °C min-1. Mass decrease to 150 °C corresponds to release of water and other lighter unbound hydrocarbons. Samples lose 6–8% of their mass due to the temperature. At main decrease the mass loss was between 62% and 69%. In some cases this decrease is in two drops that end at the temperature around 500 °C. Pyrolysis can be considered to consist of independent parallel reactions. In order to make theoretical groundwork for biomass pyrolysis available, activation energies were calculated with the help of two kinetic models (Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa model). The residuals from pyrolysed samples are determined and temperature dependent profiles of the materials were obtained

Nova vrsta špiljskoga roda Machaerites Miller, 1855 (Coleoptera, Staphylinidae, Pselaphinae) iz Hrvatske

Machaerites udrzali sp. nov., a new cavernicolous species of the tribe Bythinini from Croatia, Plitvice, Rodićeva pećina is described and illustrated; the systematic position of the species is discussed.U radu se opisuje nova špiljska vrsta Machaerites udrzali sp. nov. iz skupine Bythinini iz Hrvatske (Plitvice, Rodićeva pećina); raspravlja se o položaju vrste u sistematici

Pakistatyrus ater gen. et sp. n. iz skupine Tyrina (Coleoptera, Staphylinidae: Pselaphinae) iz Pakistana

Pakistatyrus gen. nov. and P. ater sp. nov. are described and illustrated from Pakistan. The genus is compared with the most closely related genus Hamotulus Schaufuss.U radu se opisuje novi rod Pakistatyrus i nova vrsta P. ater iz Pakistana. Rod se uspoređuje s najsrodnijim rodom Hamotulus Schaufuss

Novi kavernikolni mravoliki kornjaš iz roda Euconnus (subg. Tetramelus) iz Hrvatske (Coleoptera: Scydmaenidae)

A new cave dwelling species of Euconnus (Tetramelus) Motschulsky is described from the Croatian cave »Bazgovačka Jama«. The relationship of the new species to the species-groups longulus and oblongus is briefly discussed and the occurrences of Tetramelus in the former Yugoslavia are concisely listed.U radu se opisuje nova špiljska vrsta iz roda Euconnus (Tetramelus) Motschulsky iz Bazgovačke Jame. Ukratko se raspravlja o odnosu nove vrste prema grupama vrsta longulus i oblongus, te se daje pregled dosadašnjeg pojavljivanja roda Tetramelus u bivšoj Jugoslaviji

Nutritional, physical and sensory quality of gingerbread prepared using different sweeteners

Received: February 11th, 2023 ; Accepted: May 28th, 2023 ; Published: June 16th, 2023 ; Correspondence: [email protected] aim of the study was to investigate the effects of replacing refined beet sucrose in gingerbread with different types of sweeteners (cane sugar, sorbitol, xylitol, maple syrup). The content of fat, dry matter, dietary fibre, ash, crude protein, amino acids, selected microelements, and caloric value were determined. Organoleptic and dimensional (3D-analysis) properties were also evaluated. The fat content in samples ranged from 11.13% to 11.97%, crude fibre content - from 0.53% to 0.55%, ash content - from 0.72% to 1.06%, and crude protein - from 7.92% to 8.12%. The analysis of amino acids revealed that glutamic acid was dominant in the samples with its concentration ranging from 19.14 mg g-1 (control sample) to 23.88 mg g-1 (sample with maple syrup). The caloric value was the highest in the control sample which contained sucrose from sugar beet and the one containing xylitol (~4,480 cal g-1 ). The lowest - in the sample with maple syrup (4,247 cal g-1 ). The total content of selected microelements determined in the tested samples with atomic absorption spectrometry (Fe, Mn, Zn, Cu, Co, Ni, Cr, Cd and Pb) were within the limits permitted by the regulations of the Slovak legislation. The 3D analysis of samples with Volscan Profiler indicated that volume, width and height was better in the samples with sweeteners than in the control sample. The gingerbread with xylitol had best organoleptic properties, as evaluated by sensory panellists

Abrasive waterjet (AWJ) forces - Potential indicators of machining quality

The necessity of monitoring the abrasive waterjet (AWJ) processes increases with the spreading of this tool into the machining processes. The forces produced on the workpiece during the abrasive waterjet machining can yield some valuable information. Therefore, a special waterjet-force measuring device designed and produced in the past has been used for the presented research. It was tested during the AWJ cutting processes, because they are the most common and the best described up-to-date AWJ applications. Deep studies of both the cutting process and the respective force signals led to the decision that the most appropriate indication factor is the tangential-to-normal force ratio (TNR). Three theorems concerning the TNR were formulated and investigated. The first theorem states that the TNR strongly depends on the actual-to-limit traverse speed ratio. The second theorem claims that the TNR relates to the cutting-to-deformation wear ratio inside the kerf. The third theorem states that the TNR value changes when the cutting head and the respective jet axis are tilted so that a part of the jet velocity vector projects into the traverse speed direction. It is assumed that the cutting-to-deformation wear ratio increases in a certain range of tilting angles of the cutting head. This theorem is supported by measured data and can be utilized in practice for the development of a new method for the monitoring of the abrasive waterjet cutting operations. Comparing the tilted and the non-tilted jet, we detected the increase of the TNR average value from 1.28 +/- 0.16 (determined for the declination angle 20 degrees and the respective tilting angle 10 degrees) up to 2.02 +/- 0.25 (for the declination angle 30 degrees and the respective tilting angle of 15 degrees). This finding supports the previously predicted and published assumptions that the tilting of the cutting head enables an increase of the cutting wear mode inside the forming kerf, making the process more efficient.Web of Science1412art. no. 330

Verification of electromagnetic calorimeter concept for the HADES spectrometer

The HADES spectrometer currently operating on the beam of SIS18 accelerator in GSI will be moved to a new position in the CBM cave of the future FAIR complex. Electromagnetic calorimeter (ECAL) will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 A GeVon the beam of the new accelerator SIS100. Calorimeter will be based on 978 massive lead glass modules read out by photomultipliers and a novel front-end electronics. Secondary gamma beam with energies ranging from 81 MeV up to 1399 MeV from MAMI-C Mainz facility was used to verify selected technical solutions. Relative energy resolution was measured using modules with three different types of photomultipliers. Two types of developed front-end electronics as well as energy leakage between neighbouring modules under parallel and declined gamma beams were studied in detail

Refugial occurrence and ecology of the land snail Vertigo lilljeborgi in fen habitats in temperate mainland Europe

Vertigo lilljeborgi (Westerlund, 1871) is one of the rarest terrestrial snail species in temperate mainland Europe, traditionally considered a glacial relict there. This contrasts with its occurrence in northern Europe where it is a widespread species. This species prefers constantly wet habitats that are neutral to slightly acidic, and avoids highly alkaline conditions, which is an extremely rare ecology for a Eurasian mollusc. Until 2012, only five historical records of this species were known in mainland Europe to the south of its main distribution in northern Europe. Since then, 20 new sites have been discovered, mostly located in the Hercynian Mountains (Bohemian Massif in the Czech Republic and Massif Central in France). In comparison with the boreal European and Alpine populations, those from the Hercynian Mountains inhabit acidic, rather soligenous and productive fens, strongly dominated by Sphagnum. Vertigo lilljeborgi does not occur in some sites with apparently suitable habitats as indicated by species composition of the vegetation. We observed a surprising correspondence between the occurrence of V. lilljeborgi and mean July air temperature and we report its first fossil record from the last glacial period from Central Europe. Although the number of its sites has increased recently, these sites represent unusual and highly unique habitats, vulnerable to drainage and destruction from human activities. This calls for a need of conservation efforts in most of the newly discovered isolated sites

A Tale of Three Signatures: practical attack of ECDSA with wNAF

One way of attacking ECDSA with wNAF implementation for the scalar multiplication is to perform a side-channel analysis to collect information, then use a lattice based method to recover the secret key. In this paper, we reinvestigate the construction of the lattice used in one of these methods, the Extended Hidden Number Problem (EHNP). We find the secret key with only 3 signatures, thus reaching the theoretical bound given by Fan, Wang and Cheng, whereas best previous methods required at least 4 signatures in practice. Our attack is more efficient than previous attacks, in particular compared to times reported by Fan et al. at CCS 2016 and for most cases, has better probability of success. To obtain such results, we perform a detailed analysis of the parameters used in the attack and introduce a preprocessing method which reduces by a factor up to 7 the overall time to recover the secret key for some parameters. We perform an error resilience analysis which has never been done before in the setup of EHNP. Our construction is still able to find the secret key with a small amount of erroneous traces, up to 2% of false digits, and 4% with a specific type of error. We also investigate Coppersmith's methods as a potential alternative to EHNP and explain why, to the best of our knowledge, EHNP goes beyond the limitations of Coppersmith's methods

A Tale of Three Signatures: practical attack of ECDSA with wNAF

International audienceAttacking ECDSA with wNAF implementation for the scalar multiplication first requires some side channel analysis to collect information, then lattice based methods to recover the secret key. In this paper, we reinvestigate the construction of the lattice used in one of these methods, the Extended Hidden Number Problem (EHNP). We find the secret key with only 3 signatures, thus reaching a known theoretical bound, whereas best previous methods required at least 4 signatures in practice. Given a specifoc leakage model, our attack is more efficient than previous attacks, and for most cases, has better probability of success. To obtain such results, we perform a detailed analysis of the parameters used in the attack and introduce a preprocessing method which reduces by a factor up to 7 the total time to recover the secret key for some parameters. We perform an error resilience analysis which has never been done before in the setup of EHNP. Our construction find the secret key with a small amount of erroneous traces, up to 2% of false digits, and 4% with a specific type of error