Contact metamorphism of upper cretaceous sedimentary rocks of Rudnik

Kontaktni metamorfizam gornjokrednih sedimentnih stena na planini Rudnik ispitivan je na uzorcima iz pet bušotina. Definisano je šest varijeteta krednih stena (protolita) koji čine dve litološke jedinice izgrađene od klastičnog, karbonatnog i klastičnokarbonatnog materijala. Vulkanskom aktivnosti na Rudniku formirana su vulkanska tela koja se utiskuju duž slojevitosti sedimentnih stena, a neka ih presecaju u vidu dajkova. Starost ovog vulkanskog događaja određena je na 23.9 miliona godina. Ovaj miocenski vulkanizam doveo je do kontaktno metamorfnih promena sedimentnih stena i obrazovanja skarnova i hornfelsa. Skarnovi su klasifikovani kao epidotski, granat-vezuvijanski i granat-piroksenski, dok su hornfelsi bliže definisani po facijama na one iz albit-epidotske hornfels facije, hornblenda hornfels facije i piroksenske hornfels facije. Merenjem temperatura fluidnih inkluzija, utvrđeno je da su u vreme formiranja granata temperature hidrotermalnih fluida bile veoma visoke >560° C. Poslednja hidrotermalna faza pronađena je u kvarcu sa temperaturom homogenizacije fluidnih inkluzija oko 228° C. Granati u kontaktno metamorfnim stenama Rudnika su grosularsko-andraditskog sastava. Ispitivanjima granata na mikrosondi utvrđeno je da centar zrna ima grosularski, a obod andraditski sastav. Oštra granica između grosulara i andradita ukazuje na naglu promenu uslova kontaknog metamorfizma tokom kristalizacije granata. Termobarometrijskim modelovanjem dobijen je dijagram stabilnosti koji ukazuje na temperaturu od 430±30° C i pritisak do 800 bara. Tokom prve faze progradnog metamorfizma formirani su granati i pirokseni, a u drugoj retrogradnoj fazi formiraju se epidot i hlorit. Bitno je napomenuti da je tokom ispitivanja otkriven vezuvijan, čije prisustvo na Rudniku ranije nije zabeleženo.Contact metamorphism of the Upper Cretaceous sedimentary rocks from Rudnik Mt was studied on core samples from five boreholes. Six varieties of Cretaceous rocks (protoliths) in two distinct lithological units were distinguished. Numerous volcanic bodies that left behind volcanic event in Rudnik before 23.9 Ma are emplaced either along bedding planes in sedimentary rocks, or in a form of cutting dikes. Miocene volcanism resulted in contact metamorphism of sedimentary rocks and formation of skarn and hornfelses. Skarns are classified on epidote, garnet-vesuvianite and garnet-pyroxene skarns, while further division of hornfelses was based on facies. Thus, albite-epidote hornfels, hornblende hornfels and pyroxene hornfelses were distinguished. Thermometric measurements of fluid inclusions reflected on high temperature of hydrothermal solutions, exceeding 560° C, during the garnet growth. The last hydrothermal phase was detected by homogenization temperature of fluid inclusions in quartz at 228° C. Garnets in contact metamorphic rocks from Rudnik consider grossularite-andradite garnets. Microprobe studies revealed on grossularite in the core of garnet crystals, and their rims of andradite composition. Sharp boundary between these two garnet compositions reflects on rapid changes in conditions of contact metamorphism during garnet crystallization. According to pressure-temperature diagram based on thermobarometric modeling the temperature of 430±30° C and pressure up to 800 bars were inferred. During the first stage, i.e. prograde metamorphism formed garnet and pyroxene, whereas in the second, retrograde phase epidote and chlorite derived. It should be mentioned that mineral vesuvianite has not been recorded in Rudnik before doing these researches

Optimal Design and Control of Multi-Motor Drive System for Industrial Application

In this paper, the topology of the adjustable speed drive with active front end rectifier is considered in terms of application in multi-motor drives. A dynamic model of the rectifier with a coupled LCL filter is presented. A simulation model has been developed for the analysis of multi-motor drive system dynamics and power flow. Based on the simulation model, the functional possibilities of reversible induction motor drive with active front end converter and multiple voltage source inverters on a common DC bus at the motor side are analysed. One example of the application of a complex full regenerative multi-motor drive system on a common DC bus for an industrial crane, implemented with Siemens converters, is shown. The motor and generator mode of operation from the aspect of energy saving as well as the influence of drives on the distribution network from the aspect of higher harmonics and power factors are analysed. Siemens\u27s original software, Starter commissioning tool, for drives configuration and data acquisition is used

A hybrid rans-les method with compressible k-omegaSSTSAS turbulence model for high Reynolds number flow applications

Trodimenzionalno, kompresibilno, viskozno i nestacionarno transonično turbulentno strujanje oko krila modelirano je hibridnom RANS-LES metodom, kombiniranom s kompresibilnim k-omegaSSTSAS turbulentnim modelom. Rabljeni pristup bazira se na podjeli utjecaja fluktuirajućih i osrednjenih polja brzina u okviru subtenzora i modeliranju svakog od njih odgovarajućim turbulentnim viskozitetom. U proračunu, "RANS mod" se koristi u područjima strujnog polja koja se s prihvatljivom točnošću mogu tretirati kao stacionarna, npr. u graničnom sloju, dok se "LES mod" primjenjuje u dominantno nestacionarnim područjima, daleko od krila. Diskretizacija jednadžbi strujanja vrši se metodom konačnih razlika na nestrukturiranoj mreži. Metoda je verificirana na Onera M6 krilu. Paralelizacija se provodi dekomponiranjem mreže na subdomene i uporabom Open MPI tehnologije. Implementacija turbulentnog modela obavljena je uporabom OpenFOAM-a. Simulacija strujanja provedena je i u ANSYS Fluent-u, a rezultati dobiveni pomoću ove dvije metode uspoređeni su kako međusobno, tako i s Onera M6 eksperimentom.Three-dimensional, compressible, viscous and transient transonic turbulent flow over the wing was simulated by a hybrid RANS-LES modelling method, combined with the compressible k-omegaSSTSAS turbulence model. This approach is based on dividing the contribution of the fluctuating and the averaged velocity fields in the subgrid tensor, and modelling each of them with its corresponding turbulent viscosity. The "RANS mode" is used in flow field domains which can be treated with acceptable accuracy as relatively steady, such as in the boundary layer, while the "LES mode" is applied in the dominantly unsteady regions, far from the wing. Discretization of the governing equations is performed by Finite Volume Method on unstructured mesh. The method has been verified on the Onera M6 wing. The parallelization is achieved by decomposing the mesh into sub-domains and using the Open MPI technology. The implementation of turbulence model has been done using OpenFOAM. The flow simulation was also performed using ANSYS Fluent, and the results of the two methods were compared mutually, and with the Onera M6 experiment

THE MONOSPIRAL MOTORISED CABLE REEL IN CRANE APPLICATIONS

The main consideration of any reeling system is the effect it has on cable tensions and hence cable life. This paper explains the relationship of reel torque to cable tensions and the reasons why this relationship is so important. Such system is characterized by variable parameters, primarily a variable moment of inertia and a variable diameter of the coiled cable. For these reasons, in order to ensure proper dimensioning of the drive, it is necessary to know the motor torques that need to be developed as a function of the coiled cable. The motor should be able to develop the required torques in a very wide speed range. It is shown that for properly sizing the motor it is necessary take into account the dynamics of the cable reel drive. In this paper monospiral motorized cable reel for winding power cable in crane applications with frequency converter fed induction motor is analyzed. Also, the equipment selection procedure for the real crane with concrete data is shown. Experimental results are recorded during the crane commissioning in real condition

Giant esophageal fibrovascular polyp with clinical behaviour of inflammatory pseudotumor: A case report and the literature review

Introduction. Esophageal fibrovascular polyps are rare, benign, intraluminal, submucosal tumor-like lesions, characterized by pedunculated masses which can demonstrate enormous growth. The most frequent symptoms are dysphagia, vomiting and weight loss. Fibrovascular polyps with long stalks can regurgitate into the airways and cause asphyxia. Esophageal inflammatory pseudotumor is extremely rare lesion accompanied with various systemic manifestations as fever, anemia and thrombocytosis. Case report. We presented a 29-year-old man complaining of a long-lasting fever and dysphagia. He was found to have huge pedunculated submucosal tumor of esophagus, surgically completely resected. Histopathological examination showed that this giant tumor, 24 x 9 x 6 cm, was a fibrovascular polyp. The postoperative course was uneventful. The preoperative fever, anemia and thrombocytosis disappeared and did not recur in the postoperative course. Conclusion. We reported a patient with giant esophageal pedunculated tumor with clinical manifestations of inflammatory pseudotumor and histopathological picture of fibrovascular polyp, that we have not found described in the literature before

Giant esophageal fibrovascular polyp with clinical behaviour of inflammatory pseudotumor: A case report and the literature review

Introduction. Esophageal fibrovascular polyps are rare, benign, intraluminal, submucosal tumor-like lesions, characterized by pedunculated masses which can demonstrate enormous growth. The most frequent symptoms are dysphagia, vomiting and weight loss. Fibrovascular polyps with long stalks can regurgitate into the airways and cause asphyxia. Esophageal inflammatory pseudotumor is extremely rare lesion accompanied with various systemic manifestations as fever, anemia and thrombocytosis. Case report. We presented a 29-year-old man complaining of a long-lasting fever and dysphagia. He was found to have huge pedunculated submucosal tumor of esophagus, surgically completely resected. Histopathological examination showed that this giant tumor, 24 x 9 x 6 cm, was a fibrovascular polyp. The postoperative course was uneventful. The preoperative fever, anemia and thrombocytosis disappeared and did not recur in the postoperative course. Conclusion. We reported a patient with giant esophageal pedunculated tumor with clinical manifestations of inflammatory pseudotumor and histopathological picture of fibrovascular polyp, that we have not found described in the literature before

Anisotropic grossular-andradite garnets: Evidence of two stage skarn evolution from Rudnik, Central Serbia

This paper presents LA-ICP-MS data for garnets from the Rudnik skarn deposit (Serbia), which range from Grs45–58Adr40–52Alm2–3 in the core and Adr70–97Grs2–29Sps1 in the rim displaying anisotropy and zoning. In spite of wide compositional variations the garnets near the end-member of andradite (Adr > 90) are generally isotropic. Fe-rich rims exhibit LREE depletion and flat HREE pattern with weak negative Eu anomaly, including higher As and W contents. On the other side, the Fe-poorer core shows flat REE pattern without any significant enrichment or depletion of REE, except higher amounts of trace elements, such as U, Th and Zr. Presence of sulphide minerals indicates reduction conditions and Eu divalent state. Different REE behaviour is conditioned by Eu2+ in reduction conditions. The observed variations in optical features and garnet chemistry are the results of their two-stage evolution. The first stage and period of garnet growth is probably buffered by mineral dissolution and reactions in the country rock. The second stage is related to hydrothermal activity when W and Fe were brought into the system probably by a boiling process in the volcanic event in the late Oligocene 23.9 Ma

An assessment of burden of hospital-acquired pneumonia among abdominal surgical patients in tertiary university hospital in Serbia: A matched nested case-control study

BackgroundIn the population of abdominal surgical patients hospital-acquired pneumonia (HAP) significantly increases morbidity and mortality.Patients and methodsThrough regular hospital surveillance of patients who received abdominal operations, we identified postoperative HAP from 2007 to 2019. In an initial nested case-control study, every surgical patient with HAP was compared with three control patients without HAP. Control patients were matched to the cases by age, gender, the American Society of Anesthesiologists score, and type of surgical operation. Also, the patients with HAP, who died were compared with those who survived.ResultsMultivariate logistic regression analysis (MLRA) revealed that other postoperative infections, length of intensive care unit stay, use of H2RA, use of PPI/ H2RA, multiple transfusion, and use of vancomycin in surgical prophylaxis were independent RFs for occurrence of HAP. Also, MLRA identified that age, lenght of hospital stay, use of mechanical ventilation and ceftriaxone in HAP therapy were indepedenttly associated with poor outcome of HAP. All Acinetobacter baumannii isolates were resistant to aminoglycoside antimicrobial agents and showed carbapenem resistance. The most frequently used antibiotics in patients with HAP and without HAP were vancomycin and metronidazole, respectively.ConclusionOur study provided an insight into the burden of HAP in abdominal surgical patients, and highlighted several priority areas and targets for quality improvement