Showing papers by "Nenad Bićanić published in 2015"

A model of mudflow propagation downstream from the Grohovo landslide near the city of Rijeka (Croatia)

Abstract: . Mudflows regularly generate significant human and property losses. Analyzing mudflows is important to assess the risks and to delimit vulnerable areas where mitigation measures are required. The smoothed-particle hydrodynamics (SPH) model adopted here considers, in two phases, a granular skeleton with voids filled with either water or mud. The SPH depth-integrated numerical model (Pastor et al., 2009a) used for the present simulations is a 2-D model capable of predicting the runout distance, flow velocity, deposition pattern and the final volume of mudflows. It is based on mathematical and rheological models. In this study, the main characteristics of mudflow processes that have emerged in the past (1908) in the area downstream of the Grohovo landslide are examined, and the more relevant parameters and attributes describing the mudflow are presented. Principal equations that form the basis of the SPH depth-integrated model are reviewed and applied to analyze the Grohovo landslide and the propagation of the mudflow wave downstream of the landslide. Based on the SPH method, the runout distance, quantities of the deposited materials and the velocity of mudflow progression which occurred in the past at the observed area are analyzed and qualitatively compared to the recorded consequences of the actual event. Within the SPH simulation, the Newtonian rheological model in the turbulent flow regime and the Bingham rheological model were adopted and a comparison was made of the application of the Egashira and Hungr erosion law.

Dynamic sensitivity of a multi-block stack subjected to horizontal harmonic excitation

Abstract: Dynamic sensitivity of a one-dimensional stack of four rigid blocks with controlled initial gaps, undergoing external harmonic vibrations is investigated. Time variation of the mass inertia and the relative kinetic energy are considered as dynamic block stack attributes. Numerical simulation is based on the Non Smooth Contact Dynamics (NSCD) time integration framework Solfec (http://code.google.com/p/solfec/). Sensitivity space parameters include a range of excitation frequencies and velocity amplitudes.

The relationship between bone mineral density and lipid status and anthropometric parameters in patients with dyslipidaemia

Abstract: Cilj: Statini znacajno smanjuju rizik od kardiovaskularnih bolesti, a s obzirom na mehanizamdjelovanja slican bisfosfonatima, mogu povoljno djelovati i na kostani metabolizam. Ciljje bio istražiti povezanost između mineralne gustoce kosti (BMD) slabinske kralježnice i lijevogkuka s lipidnim i antropometrijskim parametrima u pacijenata lijecenih zbog dislipidemije. Osimtoga, cilj je bio analizirati odnos između vremenskog perioda lijecenja statinima i BMD-a. Ispitanicii metode: Ispitanici su vecinom žene u postmenopauzi (N = 65), ali i muskarci (N = 15), kojise zbog dislipidemije lijece statinima. Iz ispitivane skupine iskljuceni su oni pacijenti koji se zbogosteoporoze lijece bisfosfonatima. U svih ispitanika su kostanom denzitometrijom izmjerenevrijednosti BMD-a slabinske kralježnice i lijevog kuka. Rezultati: BMD slabinske kralježnice pozitivnokorelira s koncentracijom triglicerida u krvi (r = 0, 24, P = 0, 046), ali korelira negativno sukupnim kolesterolom (r = -0, 31, P = 0, 008), HDL kolesterolom (r = -0, 28, P = 0, 020) i LDL kolesterolom(r = -0, 35, P = 0, 004). BMD lijevog kuka korelira pozitivno s trigliceridima (r = 0, 25, P = 0, 031), dok su negativne korelacije nađene s ukupnim kolesterolom (r = -0, 30, P = 0, 011), HDL kolesterolom (r = -0, 28, P = 0, 015) i LDL kolesterolom (r = -0, 30, P = 0, 010). Vremenski periodlijecenja statinima pozitivno korelira s BMD-om slabinske kralježnice (r = 0, 23, P = 0, 048).Zakljucak: Razvidno je da postoji povezanost između kostanog metabolizma i lipidnog statusa, kao i između kostanog metabolizma i vremenskog perioda lijecenja statinima. Ipak, potrebno jeprovesti nova randomizirana klinicka istraživanja kako bi se taj odnos u potpunosti razjasnio.

Dynamic sensitivity of multi-block stacks subjected to base pulse excitation - experimental evidence and non smooth contact dynamic simulations

Abstract: Experimental and computational dynamic sensitivity study of Multi-Block Stacks subjected to Pulse Base Excitation is considered. Advanced non contact optical measuring technique based on the GOM Aramis and Pontos systems, as well as the corresponding processing software (displacement history of control sensor points, with a high resolution high speed cameras) have been applied to replace conventional displacement measuring systems and accelerometers. The Non Smooth Contact Dynamics (NSCD) time integration simulation framework SOLFEC http://code.google.com/p/solfec/ is adopted here for comparative NSCD analyses, including a sensitivity study on interface characteristics, as a validation process. Series of test experiments were conducted and recorded on a bespoke platform with and without lateral constraints in the Oxford Impact Engineering Laboratory and Rijeka University Structural Dynamics Laboratory for an extensive series of controlled pulse base excitation tests of multi block stacks configurations. Impact is generated by a pin-ball mechanism with spring and a wooden projectile, attached to an optical bench. For the NSCD simulations the base was subjected to a constant acceleration over a finite time, thereby facilitating the characterisation of multi block stacks tumbling modes of failures (global or partial), as a function of stop gap distance. Creation of well documented benchmarks for the validation of simulation paradigms for discontinuous media will be extremely valuable for researchers and code developers (non smooth contact dynamics, discrete elements, discontinuous deformation analysis), as well as for safety case engineers and industry regulators. N. Čeh, A. Pellegrino, J. F. Camenen, N. Petrinić, G. Jelenić, T. Koziara and N. Bićanić __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Effect of Statin Therapy Duration on Bone Turnover Markers in Dyslipidemic Patients

Abstract: Background and Purpose: Statins are cholesterol-lowering drugs decreasing bone resorption by inhibition of the farnesyl diphosphate synthase step in the mevalonic acid pathway and therefore are believed to have beneficial effects on bone status. The objective was to examine the relationship between statin therapy duration and bone turnover markers in dyslipidemic patients. Patients and Methods: Two hundred and eighty subjects were divided into five groups depending on duration of statin therapy: (controls 0 yrs) ; (0.1- 1.5 yrs) ; (2-5 yrs) ; (6-10 yrs) ; (11-30 yrs). ELISA method was applied on fasting serums using bone formation markers: Osteoprotegerin (pmol/l) and Osteocalcin (ng/ml) and bone resorption markers: sRANKL (pmol/l) and CrossLaps (ng/ml). In statistical analysis, multiple regressions were used. Results: A common influence of studied predictor variables was statistically significant for sRANKL, Serum CrossLaps and osteocalcin (P<0.001), while statistical significance was not found for osteoprotegerin. The largest shares of contributions were recorded in Model 2 for the statin group (40%) and BMI (36%) and in Model 1 for statin group (35%) and total cholesterol (28%). Conclusions: Statins showed favorable influence on osteocalcin and sRANKL, indicating improved bone metabolism in patients with longer duration of statin therapy.