Benign epithelial tumors of the lung are uncommon and can represent a diagnostic challenge. Herei... more Benign epithelial tumors of the lung are uncommon and can represent a diagnostic challenge. Herein, we describe one such emblematic case. A 59-year-old former smoker male was admitted to the hospital complaining of cough for a long time. A radiological examination showed a centrally excavated mass strictly connected to the visceral pleura. The patient underwent tumorectomy. At gross examination, the tumor was composed of solid and cystic areas containing clear liquid. Histological examination highlighted a sub-pleural encapsulated tumor, with foci of capsular invasion, characterized by a single layer of columnar and cuboidal epithelial cells lining moderately cellular fibro-vascular cores. A wide spectrum of immunohistochemical markers was performed. The final diagnosis was suggestive of a peripheral pulmonary papillary tumor of undetermined malignant potential. At the last follow-up, six years after surgery, no recurrence or metastases were described. Reporting this case, we would ...
Adding fibre reinforcement to concrete has a beneficial effect on the structural integrity and du... more Adding fibre reinforcement to concrete has a beneficial effect on the structural integrity and durability, enables construction cost&time savings. Because of these advantages, fibre reinforced concrete is gaining an increasing interest in development and use both in novel structures, as well as for repair, rehabilitation and strengthening of the existing structures. In order to determine the properties of the fibre reinforced concrete, that are necessary for design according to current guidelines, standardized tests are performed - most often flexural (or bending) test, conducted on the prismatic samples. The paper presents the results and analysis of flexural strength tests of samples made of steel fibres reinforced concrete. This concrete has potential for use in elements of the structures which are under tensile stresses in exploitation
Društvo građevinskih konstruktera Srbije - Simpozijum 2020, 2021
U radu je prikazano eksperimentalno određivanje prigušenja i frekventnih karakteristika modela če... more U radu je prikazano eksperimentalno određivanje prigušenja i frekventnih karakteristika modela čelične grede statičkog sistema grede sa dva prepusta. Izvršeno je merenje vertikalnih ubrzanja u tačkama u osi nosača sa odgovarajućom analizom registrovanih zapisa ubrzanja primenom Wavelet transformacije sa ciljem određivanja prigušenja i modalnih karakteristika modela grede.
Association of Sructural Engineering of Serbia - Symposium 2020, 2021
U radu je prezentovana identifikacija modalnih parametara konstrukcija dva turbo stola blokova A1... more U radu je prezentovana identifikacija modalnih parametara konstrukcija dva turbo stola blokova A1 i A2 u Termoelektrani Nikola Tesla-A u Obrenovcu-Republika Srbija, a na bazi merenja ambijentalnih vibracija. Merenje vibracija konstrukcija sprovedeno je u dve kampanje merenja pod ambijentalnom pobudom, oba puta na bloku koji je bio van pogona. Modalne frekvencije i modalni oblici ekstrahovani su koristeći tehniku dekompozicije frekventnog domena (Frequency Domain Decomposition-FDD) na osnovu registrovanih ubrzanja. Sprovedenom numeričkom analizom ustanovljene su dinamičke karakteristike analiziranih konstrukcija turbo-stolova adekvatne eksperimentalno utvrđenim.
Key aspects of glasses are controlled by the presence of excitations in which a group of particle... more Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the supercooled liquid is lowered. Some theories predict these excitations to cause a pseudo-gap in the spectrum of quasi-localised modes of the Hessian, D_L(ω), while others predict a gap in D_L(ω) that grows upon cooling. To unify these views and observations, we generate glassy configurations of controlled gap magnitude ω_c at temperature T=0, using so-called 'breathing' particles, and study how such gapped states respond to thermal fluctuations. We find that (i) the gap always fills up at finite T with D_L(ω) ≈ A_4(T) ω^4 and A_4 ∼(-E_a / T) at low T, (ii) E_a rapidly grows with ω_c, in reasonable agreement with a simple scaling prediction E_a∼ω_c^4 and (iii) at larger ω_c excitations involve fewer particles, as we rationalise, ...
U radu je predstavljen model koji pokusava objasniti eksponente kojima se skaliraju snaga i stupa... more U radu je predstavljen model koji pokusava objasniti eksponente kojima se skaliraju snaga i stupanj, daljinska snaga i stupanj te težina veza i umnožak stupnjeva cvorova koje ta veza spaja. Model je jednostavno rjesiv u slucaju beskonacne ravne povrsine na kojoj se cvorovi nalaze te ukoliko je prostorna raspodjela cvorova Poissonova. U ostalim slucajevima moguce je napraviti analiticke procjene odstupanja od rjesenja za beskonacnu ravnu povrsinu, no kvantitativno ih moramo proucavati simulacijama. Rezultati modela dobro se slažu sa podacima iz literature dobivenim na realnim mrežama. Dan je pregled nekoliko modela koji se bave transportnim mrežama. Najveca prednost modela iznesenog u ovom radu jest u tome sto kao jedini parametar koristi dimenzionalnost prostora, odnosno nema slobodnih parametara u određivanju eksponenata za razliku od vecine ostalih modela. Napravljen je plan obrade realnih podataka te cemo moci odrediti vrijednost varijabli sposobnosti povezivanja realnih zrakoplo...
According to the results of previous research, Nebojsa tower was erected most probably after the ... more According to the results of previous research, Nebojsa tower was erected most probably after the failed Turkish siege of Belgrade in 1456, as part of extensive fortification works undertaken to renew the destroyed or damaged town fortifications. In that period, around 1460, a new fortification of the Eastern bailey with the cannon tower on the protruding corner - the present day Jaksica tower - and artillery position within the rampart. For the same purpose, a new big cannon tower - the present day Nebojsa tower - was built at the entrance into the Danube port, on the bank of the river; the purpose of this tower was to protect with artillery fire the access to the lower town gates and the town port. The result of our research shows that the original appearance of the tower could be discerned. It is a multistorey building of a regular octagonal plan, and the diameter of the interior is around 8.5 meters. The dimensions of the outer sides are 2.9 to 3 meters. The outer wall surface wa...
U svijetu postoji nekoliko vrsta goriva koja se koriste u energetske svrhe te isto tako za pogon ... more U svijetu postoji nekoliko vrsta goriva koja se koriste u energetske svrhe te isto tako za pogon vozila. Neki od njih su benzinsko i dizelsko gorivo koji su dugi niz godina prisutni u siroj uporabi. Unazad nekoliko desetaka godina uz njih se povecava uporaba prirodnog i naftnog plina. U radu je objasnjena povijest koristenja plinova u kucanstvima, industriji, a naposlijetku i kao pogonska goriva za vozila. Njih se upotrebljava u vise agregatnih stanja. Prirodni plin, kao i naftni plin, pronalazi siru uporabu u kapljevitom stanju. Naftni plin se ne koristi u plinovitom stanju, dok se prirodni koristi kao stlaceni prirodni plin. Od pocetka ukapljivanja prirodnog plina pa do danas, u procesima ukapljivanja nije doslo do velikih promjena. Prvo ukapljivanje prirodnog plina seže u 19. stoljece kada je britanski kemicar i fizicar Michael Faraday obavljao pokuse ukapljivanja plinova, između ostalog i prirodnog plina. Objasnjeni su svi problemi na koje se nailazilo tijekom povijesnog razvoja...
U pomorstvu radar je jedan od najvažnijih sustava u navigaciji morem koji omogucuje upravljanje b... more U pomorstvu radar je jedan od najvažnijih sustava u navigaciji morem koji omogucuje upravljanje brodom i otkrivanje ostalih objekata na moru cak pr
In this bachelor thesis is shown develop and designing of a tractor attachment for digging holes ... more In this bachelor thesis is shown develop and designing of a tractor attachment for digging holes in ground in purpose of planting, burying pillars ect. In the introduction is described ways to dig holes. After market analysis is conclude that all attachments work on same principle but they have different design. After analysis, based on functional decomposition and morpholigic matix, were made two concepts. Two concepts were graded and Concept 2 was chosen and elaborated with technical documentation.
Key aspects of glasses are controlled by the presence of excitations in which a group of particle... more Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the supercooled liquid is lowered. Some theories predict these excitations to cause a gap in the spectrum of quasilocalized modes of the Hessian that grows upon cooling, while others predict a pseudogap D L (ω) ∼ ω α. To unify these views and observations, we generate glassy configurations of controlled gap magnitude ω c at temperature T = 0, using so-called breathing particles, and study how such gapped states respond to thermal fluctuations. We find that (i) the gap always fills up at finite T with D L (ω) ≈ A 4 (T) ω 4 and A 4 ∼ exp(−E a /T) at low T , (ii) E a rapidly grows with ω c , in reasonable agreement with a simple scaling prediction E a ∼ ω 4 c and (iii) at larger ω c excitations involve fewer particles, as we rationalize, and eventually become stringlike. We propose an interpretation of mean-field theories of the glass transition, in which the modes beyond the gap act as an excitation reservoir, from which a pseudogap distribution is populated with its magnitude rapidly decreasing at lower T. We discuss how this picture unifies the rarefaction as well as the decreasing size of excitations upon cooling, together with a stringlike relaxation occurring near the glass transition.
Basic data about the behaviour of thermoplastic high density polyethylene pipe with metal reinfor... more Basic data about the behaviour of thermoplastic high density polyethylene pipe with metal reinforcement under lateral load were obtained in a controlled laboratory environment. Ring stiffness and flexibility pipe tests are conducted. The characteristics of the pipe samples are given in this paper,and a process and test methodology according to which the pipe samples are tested which is prescribed by standards are explained. Obtained stiffness and flexibility results of pipe tests are shown, as well as characteristics of used test equipment specialized for the large diameter pipe testing (up to 2 m).
Rezni zub je element sklopa kašike bagera vedričara čija je osnovna funkcija prodiranje, sečenje ... more Rezni zub je element sklopa kašike bagera vedričara čija je osnovna funkcija prodiranje, sečenje i odvajanje razorenog materijala. Razmatranja prikazana u okviru ovog rada usmerenа su nа definisanje odgovarajuće metodologije integrisanog rаzvojа proizvoda i njegove primenu u konstruisanju reznih elemenata za bаgere vedričare. Pošto većina procesa na bageru zavisi upravo od procesa u zoni rezanja, potrebno je posvetiti posebnu pažnju procesu kontruisanja reznih zuba i njihovo testiranje u eksplotacionim uslovima. U okviru ovog rada prikazan je proces razvoja modularnog reznog elementa za bager vedričar ERS 1000/20.
Proceedings of the National Academy of Sciences, 2019
Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, ... more Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes asperity-level disorder, elastic interaction between local slip events, and inertia. For a perfectly flat and homogeneously loaded interface, we find that slip is nucleated by avalanches of asperity detachments of extension larger than a critical radius A c governed by a Griffith criterion. We find that after slip, the density of asperities at a local distance to yielding x σ presents a pseudogap P ( x σ ) ∼ ( x σ ) θ , where θ is a nonuniversal exponent that depends on the statistics of the disorder. This result makes a link between friction and the plasticity of amorphous materials where a pseudogap is also present. For friction, we find that a consequence is that stick–slip is an extremely slowly decaying finite-size effect, whi...
definitions and history of Biomechanics and Robotics, science and technology of actuation, sensin... more definitions and history of Biomechanics and Robotics, science and technology of actuation, sensing, control, integral architecture of both living and "artificial" organisms, product development, industrial robotics, general science and technology of locomotion and manipulation, biologically inspired robotics, robotic prosthetics, orthotics, assistive and augmentative devices medical robotics, etc.
Quasi-localised modes appear in the vibrational spectrum of amorphous solids at low-frequency. Th... more Quasi-localised modes appear in the vibrational spectrum of amorphous solids at low-frequency. Though never formalised, these modes are believed to have a close relationship with other important local excitations, including shear transformations and two-level systems. We provide a theory for their frequency density, DL(ω) ∼ ω α , that establishes this link for systems at zero temperature under quasi-static loading. It predicts two regimes depending on the density of shear transformations P (x) ∼ x θ (with x the additional stress needed to trigger a shear transformation). If θ > 1/4, α = 4 and a finite fraction of quasi-localised modes form shear transformations, whose amplitudes vanish at low frequencies. If θ < 1/4, α = 3 + 4θ and all quasi-localised modes form shear transformations with a finite amplitude at vanishing frequencies. We confirm our predictions numerically.
The response of amorphous materials to an applied strain can be continuous, or instead display a ... more The response of amorphous materials to an applied strain can be continuous, or instead display a macroscopic stress drop when a shear band nucleates. Such discontinuous response can be observed if the initial configuration is very stable. We study theoretically how such brittleness emerges in athermal, quasi-statically driven, materials as their initial stability is increased. We show that this emergence is well reproduced by elasto-plastic models and is predicted by a mean field approximation, where it corresponds to a continuous transition. In mean field, failure can be forecasted from the avalanche statistics. We show that this is not the case for very brittle materials in finite dimensions due to rare weak regions where a shear band nucleates. Their critical radius is predicted to follow ac ∼ (Σ − Σ b) −2 , where Σ is the stress and Σ b the stress a shear band can carry.
Journal of research in medical sciences : the official journal of Isfahan University of Medical Sciences, 2018
Pulmonary artery intimal sarcoma (PAS) is a rare mesenchymal tumor mostly diagnosed in middle-age... more Pulmonary artery intimal sarcoma (PAS) is a rare mesenchymal tumor mostly diagnosed in middle-aged women. In a 63-year-old female, the radiological findings showed cavitation in the left upper lobe of the lung and infiltrative tumor mass around the left pulmonary artery. PAS consisted of small, round tumor cells with about 80% of mitotic activity and with myxoid background and specific immunoprofile and diagnosed as undifferentiated sarcoma with round cell features type. The final diagnosis of PAS was established according to the pathohistological, chest computed tomography scan, and surgery finding.
Benign epithelial tumors of the lung are uncommon and can represent a diagnostic challenge. Herei... more Benign epithelial tumors of the lung are uncommon and can represent a diagnostic challenge. Herein, we describe one such emblematic case. A 59-year-old former smoker male was admitted to the hospital complaining of cough for a long time. A radiological examination showed a centrally excavated mass strictly connected to the visceral pleura. The patient underwent tumorectomy. At gross examination, the tumor was composed of solid and cystic areas containing clear liquid. Histological examination highlighted a sub-pleural encapsulated tumor, with foci of capsular invasion, characterized by a single layer of columnar and cuboidal epithelial cells lining moderately cellular fibro-vascular cores. A wide spectrum of immunohistochemical markers was performed. The final diagnosis was suggestive of a peripheral pulmonary papillary tumor of undetermined malignant potential. At the last follow-up, six years after surgery, no recurrence or metastases were described. Reporting this case, we would ...
Adding fibre reinforcement to concrete has a beneficial effect on the structural integrity and du... more Adding fibre reinforcement to concrete has a beneficial effect on the structural integrity and durability, enables construction cost&time savings. Because of these advantages, fibre reinforced concrete is gaining an increasing interest in development and use both in novel structures, as well as for repair, rehabilitation and strengthening of the existing structures. In order to determine the properties of the fibre reinforced concrete, that are necessary for design according to current guidelines, standardized tests are performed - most often flexural (or bending) test, conducted on the prismatic samples. The paper presents the results and analysis of flexural strength tests of samples made of steel fibres reinforced concrete. This concrete has potential for use in elements of the structures which are under tensile stresses in exploitation
Društvo građevinskih konstruktera Srbije - Simpozijum 2020, 2021
U radu je prikazano eksperimentalno određivanje prigušenja i frekventnih karakteristika modela če... more U radu je prikazano eksperimentalno određivanje prigušenja i frekventnih karakteristika modela čelične grede statičkog sistema grede sa dva prepusta. Izvršeno je merenje vertikalnih ubrzanja u tačkama u osi nosača sa odgovarajućom analizom registrovanih zapisa ubrzanja primenom Wavelet transformacije sa ciljem određivanja prigušenja i modalnih karakteristika modela grede.
Association of Sructural Engineering of Serbia - Symposium 2020, 2021
U radu je prezentovana identifikacija modalnih parametara konstrukcija dva turbo stola blokova A1... more U radu je prezentovana identifikacija modalnih parametara konstrukcija dva turbo stola blokova A1 i A2 u Termoelektrani Nikola Tesla-A u Obrenovcu-Republika Srbija, a na bazi merenja ambijentalnih vibracija. Merenje vibracija konstrukcija sprovedeno je u dve kampanje merenja pod ambijentalnom pobudom, oba puta na bloku koji je bio van pogona. Modalne frekvencije i modalni oblici ekstrahovani su koristeći tehniku dekompozicije frekventnog domena (Frequency Domain Decomposition-FDD) na osnovu registrovanih ubrzanja. Sprovedenom numeričkom analizom ustanovljene su dinamičke karakteristike analiziranih konstrukcija turbo-stolova adekvatne eksperimentalno utvrđenim.
Key aspects of glasses are controlled by the presence of excitations in which a group of particle... more Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the supercooled liquid is lowered. Some theories predict these excitations to cause a pseudo-gap in the spectrum of quasi-localised modes of the Hessian, D_L(ω), while others predict a gap in D_L(ω) that grows upon cooling. To unify these views and observations, we generate glassy configurations of controlled gap magnitude ω_c at temperature T=0, using so-called 'breathing' particles, and study how such gapped states respond to thermal fluctuations. We find that (i) the gap always fills up at finite T with D_L(ω) ≈ A_4(T) ω^4 and A_4 ∼(-E_a / T) at low T, (ii) E_a rapidly grows with ω_c, in reasonable agreement with a simple scaling prediction E_a∼ω_c^4 and (iii) at larger ω_c excitations involve fewer particles, as we rationalise, ...
U radu je predstavljen model koji pokusava objasniti eksponente kojima se skaliraju snaga i stupa... more U radu je predstavljen model koji pokusava objasniti eksponente kojima se skaliraju snaga i stupanj, daljinska snaga i stupanj te težina veza i umnožak stupnjeva cvorova koje ta veza spaja. Model je jednostavno rjesiv u slucaju beskonacne ravne povrsine na kojoj se cvorovi nalaze te ukoliko je prostorna raspodjela cvorova Poissonova. U ostalim slucajevima moguce je napraviti analiticke procjene odstupanja od rjesenja za beskonacnu ravnu povrsinu, no kvantitativno ih moramo proucavati simulacijama. Rezultati modela dobro se slažu sa podacima iz literature dobivenim na realnim mrežama. Dan je pregled nekoliko modela koji se bave transportnim mrežama. Najveca prednost modela iznesenog u ovom radu jest u tome sto kao jedini parametar koristi dimenzionalnost prostora, odnosno nema slobodnih parametara u određivanju eksponenata za razliku od vecine ostalih modela. Napravljen je plan obrade realnih podataka te cemo moci odrediti vrijednost varijabli sposobnosti povezivanja realnih zrakoplo...
According to the results of previous research, Nebojsa tower was erected most probably after the ... more According to the results of previous research, Nebojsa tower was erected most probably after the failed Turkish siege of Belgrade in 1456, as part of extensive fortification works undertaken to renew the destroyed or damaged town fortifications. In that period, around 1460, a new fortification of the Eastern bailey with the cannon tower on the protruding corner - the present day Jaksica tower - and artillery position within the rampart. For the same purpose, a new big cannon tower - the present day Nebojsa tower - was built at the entrance into the Danube port, on the bank of the river; the purpose of this tower was to protect with artillery fire the access to the lower town gates and the town port. The result of our research shows that the original appearance of the tower could be discerned. It is a multistorey building of a regular octagonal plan, and the diameter of the interior is around 8.5 meters. The dimensions of the outer sides are 2.9 to 3 meters. The outer wall surface wa...
U svijetu postoji nekoliko vrsta goriva koja se koriste u energetske svrhe te isto tako za pogon ... more U svijetu postoji nekoliko vrsta goriva koja se koriste u energetske svrhe te isto tako za pogon vozila. Neki od njih su benzinsko i dizelsko gorivo koji su dugi niz godina prisutni u siroj uporabi. Unazad nekoliko desetaka godina uz njih se povecava uporaba prirodnog i naftnog plina. U radu je objasnjena povijest koristenja plinova u kucanstvima, industriji, a naposlijetku i kao pogonska goriva za vozila. Njih se upotrebljava u vise agregatnih stanja. Prirodni plin, kao i naftni plin, pronalazi siru uporabu u kapljevitom stanju. Naftni plin se ne koristi u plinovitom stanju, dok se prirodni koristi kao stlaceni prirodni plin. Od pocetka ukapljivanja prirodnog plina pa do danas, u procesima ukapljivanja nije doslo do velikih promjena. Prvo ukapljivanje prirodnog plina seže u 19. stoljece kada je britanski kemicar i fizicar Michael Faraday obavljao pokuse ukapljivanja plinova, između ostalog i prirodnog plina. Objasnjeni su svi problemi na koje se nailazilo tijekom povijesnog razvoja...
U pomorstvu radar je jedan od najvažnijih sustava u navigaciji morem koji omogucuje upravljanje b... more U pomorstvu radar je jedan od najvažnijih sustava u navigaciji morem koji omogucuje upravljanje brodom i otkrivanje ostalih objekata na moru cak pr
In this bachelor thesis is shown develop and designing of a tractor attachment for digging holes ... more In this bachelor thesis is shown develop and designing of a tractor attachment for digging holes in ground in purpose of planting, burying pillars ect. In the introduction is described ways to dig holes. After market analysis is conclude that all attachments work on same principle but they have different design. After analysis, based on functional decomposition and morpholigic matix, were made two concepts. Two concepts were graded and Concept 2 was chosen and elaborated with technical documentation.
Key aspects of glasses are controlled by the presence of excitations in which a group of particle... more Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the supercooled liquid is lowered. Some theories predict these excitations to cause a gap in the spectrum of quasilocalized modes of the Hessian that grows upon cooling, while others predict a pseudogap D L (ω) ∼ ω α. To unify these views and observations, we generate glassy configurations of controlled gap magnitude ω c at temperature T = 0, using so-called breathing particles, and study how such gapped states respond to thermal fluctuations. We find that (i) the gap always fills up at finite T with D L (ω) ≈ A 4 (T) ω 4 and A 4 ∼ exp(−E a /T) at low T , (ii) E a rapidly grows with ω c , in reasonable agreement with a simple scaling prediction E a ∼ ω 4 c and (iii) at larger ω c excitations involve fewer particles, as we rationalize, and eventually become stringlike. We propose an interpretation of mean-field theories of the glass transition, in which the modes beyond the gap act as an excitation reservoir, from which a pseudogap distribution is populated with its magnitude rapidly decreasing at lower T. We discuss how this picture unifies the rarefaction as well as the decreasing size of excitations upon cooling, together with a stringlike relaxation occurring near the glass transition.
Basic data about the behaviour of thermoplastic high density polyethylene pipe with metal reinfor... more Basic data about the behaviour of thermoplastic high density polyethylene pipe with metal reinforcement under lateral load were obtained in a controlled laboratory environment. Ring stiffness and flexibility pipe tests are conducted. The characteristics of the pipe samples are given in this paper,and a process and test methodology according to which the pipe samples are tested which is prescribed by standards are explained. Obtained stiffness and flexibility results of pipe tests are shown, as well as characteristics of used test equipment specialized for the large diameter pipe testing (up to 2 m).
Rezni zub je element sklopa kašike bagera vedričara čija je osnovna funkcija prodiranje, sečenje ... more Rezni zub je element sklopa kašike bagera vedričara čija je osnovna funkcija prodiranje, sečenje i odvajanje razorenog materijala. Razmatranja prikazana u okviru ovog rada usmerenа su nа definisanje odgovarajuće metodologije integrisanog rаzvojа proizvoda i njegove primenu u konstruisanju reznih elemenata za bаgere vedričare. Pošto većina procesa na bageru zavisi upravo od procesa u zoni rezanja, potrebno je posvetiti posebnu pažnju procesu kontruisanja reznih zuba i njihovo testiranje u eksplotacionim uslovima. U okviru ovog rada prikazan je proces razvoja modularnog reznog elementa za bager vedričar ERS 1000/20.
Proceedings of the National Academy of Sciences, 2019
Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, ... more Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes asperity-level disorder, elastic interaction between local slip events, and inertia. For a perfectly flat and homogeneously loaded interface, we find that slip is nucleated by avalanches of asperity detachments of extension larger than a critical radius A c governed by a Griffith criterion. We find that after slip, the density of asperities at a local distance to yielding x σ presents a pseudogap P ( x σ ) ∼ ( x σ ) θ , where θ is a nonuniversal exponent that depends on the statistics of the disorder. This result makes a link between friction and the plasticity of amorphous materials where a pseudogap is also present. For friction, we find that a consequence is that stick–slip is an extremely slowly decaying finite-size effect, whi...
definitions and history of Biomechanics and Robotics, science and technology of actuation, sensin... more definitions and history of Biomechanics and Robotics, science and technology of actuation, sensing, control, integral architecture of both living and "artificial" organisms, product development, industrial robotics, general science and technology of locomotion and manipulation, biologically inspired robotics, robotic prosthetics, orthotics, assistive and augmentative devices medical robotics, etc.
Quasi-localised modes appear in the vibrational spectrum of amorphous solids at low-frequency. Th... more Quasi-localised modes appear in the vibrational spectrum of amorphous solids at low-frequency. Though never formalised, these modes are believed to have a close relationship with other important local excitations, including shear transformations and two-level systems. We provide a theory for their frequency density, DL(ω) ∼ ω α , that establishes this link for systems at zero temperature under quasi-static loading. It predicts two regimes depending on the density of shear transformations P (x) ∼ x θ (with x the additional stress needed to trigger a shear transformation). If θ > 1/4, α = 4 and a finite fraction of quasi-localised modes form shear transformations, whose amplitudes vanish at low frequencies. If θ < 1/4, α = 3 + 4θ and all quasi-localised modes form shear transformations with a finite amplitude at vanishing frequencies. We confirm our predictions numerically.
The response of amorphous materials to an applied strain can be continuous, or instead display a ... more The response of amorphous materials to an applied strain can be continuous, or instead display a macroscopic stress drop when a shear band nucleates. Such discontinuous response can be observed if the initial configuration is very stable. We study theoretically how such brittleness emerges in athermal, quasi-statically driven, materials as their initial stability is increased. We show that this emergence is well reproduced by elasto-plastic models and is predicted by a mean field approximation, where it corresponds to a continuous transition. In mean field, failure can be forecasted from the avalanche statistics. We show that this is not the case for very brittle materials in finite dimensions due to rare weak regions where a shear band nucleates. Their critical radius is predicted to follow ac ∼ (Σ − Σ b) −2 , where Σ is the stress and Σ b the stress a shear band can carry.
Journal of research in medical sciences : the official journal of Isfahan University of Medical Sciences, 2018
Pulmonary artery intimal sarcoma (PAS) is a rare mesenchymal tumor mostly diagnosed in middle-age... more Pulmonary artery intimal sarcoma (PAS) is a rare mesenchymal tumor mostly diagnosed in middle-aged women. In a 63-year-old female, the radiological findings showed cavitation in the left upper lobe of the lung and infiltrative tumor mass around the left pulmonary artery. PAS consisted of small, round tumor cells with about 80% of mitotic activity and with myxoid background and specific immunoprofile and diagnosed as undifferentiated sarcoma with round cell features type. The final diagnosis of PAS was established according to the pathohistological, chest computed tomography scan, and surgery finding.
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Papers by Marko Popović