A model of surface roughness constitution in the metal cutting process applying tools with defined stereometryStanisĺaw Adamczak
, Edward Miko
, Franc Čuš
, 2009, izvirni znanstveni članek
Opis: The process of surface roughness formation is complex and dependent on numerous factors. The analysis of the latest reports on the subject shows that mathematical relationships used for determining surface irregularities after turning and milling are not complete or accurate enough and, therefore, need to be corrected. A new generalized mathematical model of roughness formation was developed for surfaces shaped with round-nose tools. The model provides us with a quantitative analysis of the effects of the tool representation, undeformed chip thickness, tool vibrations in relation to the workpiece, tool runout (for multicutter tools) and, indirectly, also tool wear. This model can be used to prepare separate models for most of the typical machining operations. Surface roughness is represented here by two parameters Ra and Rt. Simulations carried out for this model helped to develop nomograms which can be used for predicting and controlling the roughness Ra of surfaces sculptured by face milling.
Ključne besede: metal cutting, surface roughness, finishing, face milling
Objavljeno: 31.05.2012; Ogledov: 1078; Prenosov: 9
Povezava na celotno besedilo
A novel metalloprotease from Bacillus cereus for protein fibre processingFernanda de Sousa
, Suzana Jus
, Anita Erbel
, Vanja Kokol
, Artur Cavaco-Paulo
, Georg M. Gübitz
, 2007, izvirni znanstveni članek
Opis: A novel protease produced by Bacillus cereus grown on wool as carbon and nitrogen source was purified. B. cereus protease is a neutral metalloprotease with a molecular mass of 45.6 kDa. The optimum activity was at 45 °C and pH 7.0. The substrate specificity was assessed using oxidized insulin B-chain and synthetic peptide substrates. The cleavage of the insulin B-chain was determined to be Asn3, Leu6, His10-Leu11, Ala14, Glu21, after 12 h incubation. Among the peptide substrates, the enzyme did not exhibit activity towards ester substrates; with p-nitroanilide, the kinetic data indicate that aliphatic and aromatic amino acids were the preferred residues at the P1 position. For furylacryloyl peptides substrates, which are typical substrates for thermolysin, the enzyme exhibited high hydrolytic activity with a Km values of 0.858 and 2.363 mM for N-(3-[2-Furyl]acryloyl)-Ala-Phe amide and N-(3-[2-Furyl]acryloyl)-Gly-Leu amide, respectively. The purified protease hydrolysed proteins substrates such as azocasein, azocoll, keratin azure and wool.
Ključne besede: textile finishing, enzymatic modification, wool fibre, enzymes, Bacilus cereus, specificity, kinetics, metalloprotease
Objavljeno: 01.06.2012; Ogledov: 896; Prenosov: 36
Povezava na celotno besedilo
Multivariate analysis and chemometric characterisation of textile wastewater streamsDarja Kavšek
, Tina Jerič
, Alenka Majcen Le Marechal
, Simona Vajnhandl
, Adriána Bednárová
, Darinka Brodnjak-Vončina
, 2013, izvirni znanstveni članek
Opis: The aim of this work was to design a quick and reliable method for the evaluation and classification of wastewater streams into treatable and non-treatable effluents for reuse/recycling. Different chemometric methods were used for this purpose handling the enormous amount of data, and additionally to find any hidden information, which would increase our knowledge and improve the classification. The data obtained from the processes description, together with the analytical results of measured parameters' characterising the wastewater of a particular process, enabled us to build a fast-decision model for separating different textile wastewater outlets. Altogether 49 wastewater samples from the textile finishing company were analysed, and 19 different physical chemical measurements were performed for each of them. The resulting classification model was aimed at an automated decision about the choice of treatment technologies or a prediction about the reusability of wastewaters within any textile finishing or other company having similar characteristics of wastewater streams.
Ključne besede: textile finishing wastewater, chemometrics, multivariate data analysis, wastewater treatment
Objavljeno: 10.07.2015; Ogledov: 758; Prenosov: 15
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