36 research outputs found
Neuro-genetic optimization of disc brake performance at elevated temperatures
Osnovni problem u radu koÄnica motornih vozila je pad njihovih performansi na poviÅ”enim temperaturama u kontaktu frikcionog para koÄnice (koÄnog diska i disk ploÄice). PoveÄanje temperature u kontaktu frikcionog para koÄnice Äesto dovodi do pada vrednosti momenta koÄenja u toku ciklusa koÄenja, a samim tim i do smanjenja izlaznih performansi koÄnice. Da bi se obezbedila stabilnost momenta koÄenja u toku ciklusa koÄenja, razvijen je optimizacioni model na bazi dinamiÄkih veÅ”taÄkih neuronskih mreža. Razvijeni model je iskoriÅ”Äen za modeliranje složenih sinergijskih uticaja koji dovode do pojave triboloÅ”kih fenomena koji utiÄu na izlazne performanse disk koÄnice. DinamiÄki optimizacioni neuronski model performansi disk koÄnice je razvijen na bazi rekurentnih neuronskih mreža. Model predviÄa dinamiÄku promenu momenta koÄenja u zavisnosti od trenutnih vrednosti pritiska aktiviranja koÄnice, brzine i temperature u kontaktu frikcionog para u toku ciklusa koÄenja. Genetski algoritmi su integrisani sa neuronskim dinamiÄkim modelom u cilju optimizacije pritiska aktiviranja koÄnice koji u toku ciklusa koÄenja treba da obezbedi željenu vrednost momenta koÄenja. Ovakav hibridni, neuro-genetski, model je pokazao moguÄnost uspeÅ”ne optimizacije vrednosti hidrauliÄkog pritiska aktiviranja koÄnice, potreban da bi se postigle stabilne i maksimizirane izlazne performanse koÄnice u toku ciklusa koÄenja.The basic problem of automotive brakes operation is the decreasing of their performance at elevated temperatures in the contact of friction pair (brake disc and brake pad). Increasing of the brake interface temperature often causes decreasing of braking torque during a braking cycle. In order to provide the stable level of braking torque during a braking cycle, the neural network based optimization model of the disc brake performance has been developed. The dynamic neural networks have been employed for modelling of complex synergy of tribological phenomena that affects the final disc brake performance at elevated temperatures. The dynamic optimization neural network model of disc brake performance at elevated temperatures has been developed using recurrent neural networks. It predicts the braking torque versus the dynamic change of the brake actuation pressure, sliding speed and the brake interface temperature in a braking cycle. Genetic algorithms were integrated with the neural network model for optimization of the brake actuation pressure in order to obtain the desired level of braking torque. This hybrid, neuro-genetic model was successfully used in optimization of the brake hydraulic pressure level needed to achieve the maximum and stable brake performance during a braking cycle
Neuro-genetic optimization of disc brake performance at elevated temperatures
Osnovni problem u radu koÄnica motornih vozila je pad njihovih performansi na poviÅ”enim temperaturama u kontaktu frikcionog para koÄnice (koÄnog diska i disk ploÄice). PoveÄanje temperature u kontaktu frikcionog para koÄnice Äesto dovodi do pada vrednosti momenta koÄenja u toku ciklusa koÄenja, a samim tim i do smanjenja izlaznih performansi koÄnice. Da bi se obezbedila stabilnost momenta koÄenja u toku ciklusa koÄenja, razvijen je optimizacioni model na bazi dinamiÄkih veÅ”taÄkih neuronskih mreža. Razvijeni model je iskoriÅ”Äen za modeliranje složenih sinergijskih uticaja koji dovode do pojave triboloÅ”kih fenomena koji utiÄu na izlazne performanse disk koÄnice. DinamiÄki optimizacioni neuronski model performansi disk koÄnice je razvijen na bazi rekurentnih neuronskih mreža. Model predviÄa dinamiÄku promenu momenta koÄenja u zavisnosti od trenutnih vrednosti pritiska aktiviranja koÄnice, brzine i temperature u kontaktu frikcionog para u toku ciklusa koÄenja. Genetski algoritmi su integrisani sa neuronskim dinamiÄkim modelom u cilju optimizacije pritiska aktiviranja koÄnice koji u toku ciklusa koÄenja treba da obezbedi željenu vrednost momenta koÄenja. Ovakav hibridni, neuro-genetski, model je pokazao moguÄnost uspeÅ”ne optimizacije vrednosti hidrauliÄkog pritiska aktiviranja koÄnice, potreban da bi se postigle stabilne i maksimizirane izlazne performanse koÄnice u toku ciklusa koÄenja.The basic problem of automotive brakes operation is the decreasing of their performance at elevated temperatures in the contact of friction pair (brake disc and brake pad). Increasing of the brake interface temperature often causes decreasing of braking torque during a braking cycle. In order to provide the stable level of braking torque during a braking cycle, the neural network based optimization model of the disc brake performance has been developed. The dynamic neural networks have been employed for modelling of complex synergy of tribological phenomena that affects the final disc brake performance at elevated temperatures. The dynamic optimization neural network model of disc brake performance at elevated temperatures has been developed using recurrent neural networks. It predicts the braking torque versus the dynamic change of the brake actuation pressure, sliding speed and the brake interface temperature in a braking cycle. Genetic algorithms were integrated with the neural network model for optimization of the brake actuation pressure in order to obtain the desired level of braking torque. This hybrid, neuro-genetic model was successfully used in optimization of the brake hydraulic pressure level needed to achieve the maximum and stable brake performance during a braking cycle
Structure and properties of ZnO/ZnMn2O4 composite obtained by thermal decomposition of terephthalate precursor: Scientific paper
A biphasic [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]Ā·H2O}nĀ comĀplex material, I (dipya = 2,2ā-dipyridylamine, tpht2āĀ = dianion of terephthalatic acid) was synthesized by ligand exchange reaction and characterized by XRPD and FTIR spectroscopy. A ZnO/ZnMn2O4Ā composite, II, has been prepared via thermal decomposition of I in an air atmosphere at 450 Ā°C. XRPD, FTIR and FESEM analyses of II revealed the simultaneous presence of spherical nanoĀparticles of wurtzite ZnO and elongated nanoparticles of spinel ZnMn2O4. The specific surface area of II was determined by the BET method, whereas the volume and average size of the mesopores were calculated in accordance with the BJH method. The measurements of the mean size, polydispersity index and zeta potential showed colloidal instability of II. Two band gap values of 2.4 and 3.3 eV were determined using UVāVis diffuse reflectance spectroscopy, while the measurements of photoluminescence revealed that II is active in the blue region of the visible spectrum. Testing of composite II as a pigmentary material showed that it can be used for the colouring of a ceramic glaze
Poster presentation: "Cysteine and modified cysteine as green inhibitors of aluminum alloy corrosion"
In its pure form, aluminum is easy to process and has a high level of corrosion resistance. However, due to its low strength the possibility of application of pure aluminum is reduced. When alloyed, aluminum alloys are widely used material in construction, different industries, airspace and military. Commercial 7000 series aluminum alloys have zinc as the main alloying element, followed by magnesium. This 7000 aluminum series offers a very high strength when heat-treated, which comes from its composition. The life time of these alloys is reduced due to corrosion damage. It is known that corrosion directly or indirectly affects materials, human health and safety, and it causes global economic and environmental problem. The use of inhibitors in corrosion protection is the simplest, most economical and most efficient approach that is routinely used to āreduceā this problem in industry. The most widely used inorganic inhibitors, such as chromates, are not safe, causing health and safety problems due to their toxicity. Organic compounds have increased interest of the scientific community as potential inhibitors in exchange for the most commonly used. The aim of this study was to investigate new green, eco-friendly inhibitors from the group of amino acid and their combination with lanthanides. For the purposes of this investigation, cerium-cysteine complex was synthesized and analyzed by Fourier-Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM / EDS), Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Linear Sweep Voltammetry (LSV) analyses. SEM/EDS was used for morphological analysis and to determine the composition of the aluminum alloy on which the electrochemical tests have been performed. Electrochemical measurements (PEIS, LSV) were erformed in order to test the inhibitory efficacy in 0.1M NaCl at room temperature. Different concentrations of cysteine and Ce-cysteine complex were examined to optimize the process. The adsorption of the inhibitor follows the Langmuir isotherm, and based on the electrochemical results and calculated thermodynamic potential (Gibbs free energy) it can be concluded that both cysteine and cerium-cysteine complex are mixed type of inhibitors. It can be concluded that both cysteine and Ce-cysteine complex inhibitors satisfactory inhibition effect on aluminum alloy corrosion.Abstract: [https://cer.ihtm.bg.ac.rs/handle/5448]Poster presented at: VII International congress Engineering, environment and materials in process industry EEM2021, March 17-19, 2021 Jahorina, Republic of Serbia, Bosnia and Herzegovin
Cysteine and modified cysteine as green inhibitors of aluminum alloy corrosion
In its pure form, aluminum is easy to process and has a high level of corrosion resistance. However, due to its low strength the possibility of application of pure aluminum is reduced. When alloyed, aluminum alloys are widely used material in construction, different industries, airspace and military. Commercial 7000 series aluminum alloys have zinc as the main alloying element, followed by magnesium. This 7000 aluminum series offers a very high strength when heat-treated, which comes from its composition. The life time of these alloys is reduced due to corrosion damage. It is known that corrosion directly or indirectly affects materials, human health and safety, and it causes global economic and environmental problem. The use of inhibitors in corrosion protection is the simplest, most economical and most efficient approach that is routinely used to āreduceā this problem in industry. The most widely used inorganic inhibitors, such as chromates, are not safe, causing health and safety problems due to their toxicity. Organic compounds have increased interest of the scientific community as potential inhibitors in exchange for the most commonly used. The aim of this study was to investigate new green, eco-friendly inhibitors from the group of amino acid and their combination with lanthanides. For the purposes of this investigation, cerium-cysteine complex was synthesized and analyzed by Fourier-Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM / EDS), Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Linear Sweep Voltammetry (LSV) analyses. SEM/EDS was used for morphological analysis and to determine the composition of the aluminum alloy on which the electrochemical tests have been performed. Electrochemical measurements (PEIS, LSV) were erformed in order to test the inhibitory efficacy in 0.1M NaCl at room temperature. Different concentrations of cysteine and Ce-cysteine complex were examined to optimize the process. The adsorption of the inhibitor follows the Langmuir isotherm, and based on the electrochemical results and calculated thermodynamic potential (Gibbs free energy) it can be concluded that both cysteine and cerium-cysteine complex are mixed type of inhibitors. It can be concluded that both cysteine and Ce-cysteine complex inhibitors satisfactory inhibition effect on aluminum alloy corrosion
Zeleni inhibitori korozije sa cisteinom i kompleksom cerijum-cisteina na 7000 seriji aluminijumske legure
The aim of this study was to investigate environmentally-friendly corrosion inhibitors based on the cerium-cysteine and their effect on 7xxx series aluminum alloy. The cysteine and cerium-cysteine complex structures were analyzed by Fourier-Transform Infrared spectroscopy (FTIR). The structure of cerium-cysteine was additionally determined using Nuclear Magnetic Resonance (NMR) and Elemental Analysis. Inhibitors efficiency was analyzed with Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic polarization techniques in 0.1M NaCl at room temperature, while Scanning Electron Microscopy analyzed the surface appearance and microstructure of the tested aluminum alloy with Energy Dispersive Spectroscopy (SEM / EDS) and Optical Microscope (OM). Different amounts of cysteine were examined in order to find an optimal concentration of inhibitor. The adsorption of the inhibitors followed the Langmuir isotherm, and based on the EIS results and calculated thermodynamic potential (Gibbs free energy), cysteine and cerium-cysteine proved to be good inhibitors for tested aluminum alloy. The optimal cysteine concentration of 0.06 mM as a corrosion inhibitor of 7xxx series aluminum alloy was determined. EIS diagrams confirmed that cysteine showed better inhibition than Ce-Cys complex
Dietary fibers and bread: Attitudes, beliefs and knowledge among young population
The link between dietary fibers and prevention of non-communicable diseases is well documented in the existing scientific literature. Despite that, most of the population still do not have enough knowledge about fibers and their presence in certain food. This study intended to make an insight in the knowledge of the Serbian young population about dietary fibers and bioactive compounds through a questionnaire survey. A survey was conducted to a sample of 173 individuals, (37% male and 63% female) randomly selected among students from elementary, high school and university in the Novi Sad municipality. Topics covered by the questionnaire included knowledge of the term dietary fiber, fiber content in different bread types, the relationship between fibers and health and bioactive compounds sources in food. The results for each of the particular topics addressed varied among studied groups, but generally level of knowledge was related to the education level. The highest overall knowledge about dietary fibers and bioactive compounds was expressed by the university students, although elementary and high school students showed a considerable level of knowledge on the subject. Male participants appeared as more familiar with the questions related to bioactive compounds, while females were more informed on questions regarding dietary fiber. This survey revealed that young population in Serbia is well informed about the contribution of dietary fiber and bioactive compounds in promoting health. However, further expansion of existing knowledge will be beneficial in order to improve general health of the entire community
Development of SARS-CoV-2 N-protein specific capture ELISA
Ta na dijagnoza ljudi sa sumnjom na infekciju SARS-CoV-2 je od suŔtinskog zna aja za
suzbijanje globalnog Ŕirenja COVID-19. Prisustvo SARS-CoV-2 može se otkriti RT-PCRom (otkriva RNK virusa) ili detekcijom prisustva virusnih antigena u bioloŔkim te nostima
ELISA-om ili sli nom tehnikom koje koriste antitela razvijena u životinjama. Cilj studije
je bio uspostavljanje kvantitativnog testa koji se zasniva na koriÅ” enju poliklonskih seruma
za rutinsko odre ivanje koncentracije SARS-CoV-2 nukleokapsidnog proteina merenjam
apsorbancije u standardnoj mikrotitarskoj plo ici sa 96 bunara. Za potrebe razvoja testa
proizveden je rekombinantni N-protein i koriŔ en za proizvodnju antiseruma u miŔevima i
ze evima. Proizvedeni antiserumi su pre iÅ” eni i odre en im je titar. Poliklonskiantiserumi
visokog afiniteta specifi ni za N-protein koriÅ” eni su za razvoj ELISA testa specifi nog za
ovaj protein. Test se zasniva na koriŔ enju poliklonskih seruma miŔeva koji su adherirani
na dno bunara mikrotitarske plo ice za hvatanje N-proteina iz uzorka. Razli ite
koncentracije rekombinantnog N-proteina su koriÅ” ene za standardnu krivu za
kvantifikaciju proteina. N-protein vezan za antitela miŔeva je detektovan ze jim
poliklonskim serumom i anti-ze jim antitelom povezanim sa enzimom koji obezbe uje
spektrofotometrijsko merenje. UspeŔno smo razvili prototip ELISA testa za kvantifikaciju
N-proteina sa granicom detekcije u opsegu od ng/mL. Prose na vrednost LOD za prototip
ELISA testa za detekciju N-proteina je 9,2 ng/mL, dok je prose na vrednost LOQ
10,2 ng/mL. Pokazali smo da su proizvedeni poliklonski antiserumi pogodni za detekciju
N-proteina sa sli nim ili boljim afinitetom i specifi noÅ” u od komercijalnih antitela.
ŠtaviŔe, prototip ELISA testa se može koristiti sa zadovoljavaju om pouzdanoŔ u za
kvantifikaciju N-proteina u uzorcima bogatim proteinima, poput ljudskih seruma.The accurate diagnosis of people with suspected infection with the SARS-CoV-2 is
essential to curb the global spread of COVID-19. The presence of SARS-CoV-2 can be
detected by RT-PCR (it detects RNA of the virus) or by the presence of viral antigens in
biological fluids in ELISA or similar techniques using antibodies developed in animals.
The aim of the study was the establishment of a quantitative polyclonal sera-based test for
routine measurement of the concentration of SARS CoV-2 nucleocapsid protein using
absorbance measurement in a standard 96-well microtiter plate. For the purposes of the test
development, recombinant N protein was produced and used for the production of mice
and rabbit antisera. Produced antisera were purified and titer was determined. High-affinity
polyclonal N-protein specific antisera were used for N-protein specific ELISA test
development. The test is based on mice polyclonal sera adhered to microtiter plate bottom
for the capture of the N protein from the specimen. Various concentrations of the
recombinant N-protein were used to generate a standard curve for protein quantification.
The N-protein bound to the mice antibodies was detected with rabbit polyclonal sera and
anti-rabbit antibody coupled to an enzyme that provides spectrophotometric measurement.
We have successfully developed the prototype ELISA for the quantification of N-protein
with the detection limit being in the range of ng/mL. The average LOD value for the
prototype ELISA was determined to be 9.2 ng/mL, while the average LOQ value was
10.2 ng/mL. We have demonstrated that produced polyclonal antisera are suitable for the
detection of N-protein with affinity and specificity similar to, or better than commercial
antibodies. Furthermore, the prototype ELISA can be used with satisfactory confidence for
quantification of the N-protein in protein-rich samples, similar to human sera.Poster: [https://cherry.chem.bg.ac.rs/handle/123456789/5362
Development of SARS-CoV-2 N-protein specific capture ELISA
Ta na dijagnoza ljudi sa sumnjom na infekciju SARS-CoV-2 je od suŔtinskog zna aja zasuzbijanje globalnog Ŕirenja COVID-19. Prisustvo SARS-CoV-2 može se otkriti RT-PCRom (otkriva RNK virusa) ili detekcijom prisustva virusnih antigena u bioloŔkim te nostimaELISA-om ili sli nom tehnikom koje koriste antitela razvijena u životinjama. Cilj studijeje bio uspostavljanje kvantitativnog testa koji se zasniva na koriŔ enju poliklonskih serumaza rutinsko odre ivanje koncentracije SARS-CoV-2 nukleokapsidnog proteina merenjamapsorbancije u standardnoj mikrotitarskoj plo ici sa 96 bunara. Za potrebe razvoja testaproizveden je rekombinantni N-protein i koriŔ en za proizvodnju antiseruma u miŔevima ize evima. Proizvedeni antiserumi su pre iŔ eni i odre en im je titar. Poliklonskiantiserumivisokog afiniteta specifi ni za N-protein koriŔ eni su za razvoj ELISA testa specifi nog zaovaj protein. Test se zasniva na koriŔ enju poliklonskih seruma miŔeva koji su adheriranina dno bunara mikrotitarske plo ice za hvatanje N-proteina iz uzorka. Razli itekoncentracije rekombinantnog N-proteina su koriŔ ene za standardnu krivu zakvantifikaciju proteina. N-protein vezan za antitela miŔeva je detektovan ze jimpoliklonskim serumom i anti-ze jim antitelom povezanim sa enzimom koji obezbe ujespektrofotometrijsko merenje. UspeŔno smo razvili prototip ELISA testa za kvantifikacijuN-proteina sa granicom detekcije u opsegu od ng/mL. Prose na vrednost LOD za prototipELISA testa za detekciju N-proteina je 9,2 ng/mL, dok je prose na vrednost LOQ10,2 ng/mL. Pokazali smo da su proizvedeni poliklonski antiserumi pogodni za detekcijuN-proteina sa sli nim ili boljim afinitetom i specifi noŔ u od komercijalnih antitela.ŠtaviŔe, prototip ELISA testa se može koristiti sa zadovoljavaju om pouzdanoŔ u zakvantifikaciju N-proteina u uzorcima bogatim proteinima, poput ljudskih seruma.The accurate diagnosis of people with suspected infection with the SARS-CoV-2 isessential to curb the global spread of COVID-19. The presence of SARS-CoV-2 can bedetected by RT-PCR (it detects RNA of the virus) or by the presence of viral antigens inbiological fluids in ELISA or similar techniques using antibodies developed in animals.The aim of the study was the establishment of a quantitative polyclonal sera-based test forroutine measurement of the concentration of SARS CoV-2 nucleocapsid protein usingabsorbance measurement in a standard 96-well microtiter plate. For the purposes of the testdevelopment, recombinant N protein was produced and used for the production of miceand rabbit antisera. Produced antisera were purified and titer was determined. High-affinitypolyclonal N-protein specific antisera were used for N-protein specific ELISA testdevelopment. The test is based on mice polyclonal sera adhered to microtiter plate bottomfor the capture of the N protein from the specimen. Various concentrations of therecombinant N-protein were used to generate a standard curve for protein quantification.The N-protein bound to the mice antibodies was detected with rabbit polyclonal sera andanti-rabbit antibody coupled to an enzyme that provides spectrophotometric measurement.We have successfully developed the prototype ELISA for the quantification of N-proteinwith the detection limit being in the range of ng/mL. The average LOD value for theprototype ELISA was determined to be 9.2 ng/mL, while the average LOQ value was10.2 ng/mL. We have demonstrated that produced polyclonal antisera are suitable for thedetection of N-protein with affinity and specificity similar to, or better than commercialantibodies. Furthermore, the prototype ELISA can be used with satisfactory confidence forquantification of the N-protein in protein-rich samples, similar to human sera.Abstract: [https://cherry.chem.bg.ac.rs/handle/123456789/5361