A note on permeability for a network of thin channels

We study a viscous flow through a periodic network of thin channels with small period and small thickness . We consider two cases limε --> 0 (limδ --> 0) and limδ --> 0 (limε --> 0). In both cases the limit (homogenized) problem is the Darcy law with the same permeability tensor

Existence, uniqueness and non-regularity of the solution to the Neumann problem for the mono-dimensional compressible Reynolds equation

In this paper we construct the solution of the Dirichlet problem for a mono-dimensional compressible Reynolds equation and we prove its uniqueness. The solution is smooth, if the total mass of the fluid is sufficiently large, but it is not regular if the total mass is insufficient. The reason for such deterioration of the solution is vacuum that appears in part of the domain

A Note on Boundary Conditions for the LWR Model

The paper studies the boundary conditions for the standard LWR model describing the traffic flow. The notion of the BLN (Bardos, Leroux and Nédélec) condition is described. In the context of traffic flow the BLN conditions have some natural interpretation. The conditions on the density and on the flow and their meaning in real-life situations are discussed. KEY WORDS: LWR model, traffic flow, hyperbolic conservation law, boundary condition

Utjecaj kvalitete pripreme površine osnovnog materijala na otpornost naštrcanog sloja radijalnom i aksijalnom smiku

For the purpose of this experiment, respective surfaces of 42CrMo4 base material specimens were prepared for spraying using different technologies: turning, cutting of radial notches and cutting of axial notches. Gas aided thermal spraying of wire material was performed, laying a first layer of a nickel aluminum compound and a final Chrome Molybdenum Steel coating. Metallographic structure analysis and hardness measurement suggested that surface preparation quality does not affect hardness of the sprayed layer, but its thickness. Using a suitable tool, specimens were examined on radial and axial shear and these results were compared to previous ones. It could be determined that the notch size significantly affects both the thickness of the intermediate layer and its even distribution around the edge of the notch. A smaller radial notch allows for a higher torque momentum at radial shear, whilst best overall properties are achieved with axial notches subjected to radial loads. Testing axial shear, the cutting power proved dependant of the depth of radial notches, where low depth was inherent with low shear resistance.Na ispitnim uzorcima osnovnog materijala 42CrMo4 izvršene su različite pripreme površine: tokarenjem, narezivanjem aksijalnih i narezivanjem radijalnih utora. Izvršeno je plinsko naštrcavanje žicom: međusloj nikl- aruminid i završnog sloja Cr-Mo čelik. Metalografskim pretragama strukture i kontrolom tvrdoća utvrđeno je da kvaliteta pripreme površine ne utječe značajno na tvrdoću ali utječe na postignutu debljinu sloja. Odgovarajućim alatom izvršena su ispitivanja uzoraka na radijalni i na aksijalni smik. Međusobnom usporedbom rezultata ovih mjerenja s rezultatima kontrole tvrdoće i metalografskim pretragama strukture dolazi se do zaključka da veličina utora značajno djeluje na debljinu podsloja a pogotovo na njegovu ravnomjerno naštrcavanje po obodu utora. Sitniji radijalni utor doprinosi povećanju momenta zakretanja pri radijalnom smiku, ali se najbolja svojstva postižu u uvjetima aksijalnih utora radijalno opterećenih. Pri ispitivanju na aksijalni smik sila odreza ovisi o dubini radijalnih utora pri čemu mala dubina utora daje i malu otpornost na smik

HANTAVIRUS INFECTION - EPIDEMIOLOGICAL CHARACTERISTICS IN THE AREA OF THE REPUBLIC OF CROATIA DURING THE COVID-19 PANDEMIC

Introduction: Hantaviruses are the causative agents of hemorrhagic fever with renal syndrome (HGBS). People are most often infected by inhaling a contaminated aerosol, but infection can also occur through contaminated food or water. On average, eighteen people fall ill with HGBS per year outside of epidemics. Men between the ages of 20 and 40, especially farmers, soldiers, foresters and hikers, are most often affected. Famous hotspots in Croatia are Lika, Gorski kotar and Medvednica. Objective: To analyze the frequency and epidemiological characteristics of hantavirus infections in the Republic of Croatia during the COVID-19 pandemic. Materials and methods: Data on the incidence of HGBS according to counties, seasonal occurrence, age groups and gender were analyzed, as well as the connection of recommendations for being in nature as part of the suppression of the Covid-19 pandemic to a potential increase in the number of HGBS patients. Retrospective analysis was used to process the data collected at the Croatian Institute of Public Health, and descriptive methods were used to perform statistical analyzes in the Microsoft Excel software system. Results: In the period from 2019 to 2021, there were 547 patients with HGBS, with men suffering more often than women (78.0% vs. 22.0%). The highest activity was recorded in Primorje-Gorski Kotar and Lika-Senj counties from March to August in the age groups of 30 to 39 years. In 2021, 332 patients were reported, which is more than the average, and this can be connected to the more frequent stay of people in nature due to recommendations to reduce the number of patients with the COVID-19 disease. Conclusion: The study of the epidemiological features of hantavirus infections is important for public health because it enables the identification of areas with a higher risk of infection, the recognition of epidemics and the adoption of appropriate control and prevention measures

ODREĐIVANJE KRIOPROTEKTORSKE DJELOTVORNOSTI -KARAGENA NA MIOFIBRILARNE PROTEINE PILECEG MESA POMOCU DIFERENCIJALNE MOTRIDBENE KALORIMETRIJE (DSC)

Diferencijalnom motridbenom kalorimetrijom (DSC) odreivana je krioprotektorska djelotvornost -karagena na miofibrilarne proteine pileceg surimija.Uzorci pileceg surimija pomiješani su s natrijevim-tripolifosfatom (w = 0.3%), i u razlicitim masenim omjerima s -karagenom (w = 0.6-3%, i NaCl (w = 2-10 %). Uzorci surimija pileceg mesa pripremljeni su u laboratorijskim uvjetima od mesa mladih tovljenih pilica – brojlera, zamrznuti brzim postupkom i uskladišteni 3 mjeseca na -25 °C. Temperature pocetka denaturacije (To), temperature denaturacije (Tp) i temperature završetka denaturacije (Te) te promjene entalpije denaturacije !H odreene su iz DSC termograma. Diferencijalna motridbena kalorimetrija (DSC) je pokazala da povecanje masenog udjela -karagena rezultira pomakom temperatura denaturacije miozina i aktina prema višim vrijednostima. Povecanje masenog udjela -karagena rezultiralo je povecanjem, a masenog udjela NaCl smanjenjem, vrijednosti promjena entalpija denaturacije !H miozina i aktina. S obzirom da su vrijednosti promjena entalpija denaturacije !H u izravnoj vezi s kolicinom nedenaturiranih proteina, više vrijednosti !H upucuju na bolje krioprotektorsko djelovanje -karagena