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Medic S.,Karlovac University of Applied science | Kondic Z.,Varazdin University of Applied science | Runje B.,University of Zagreb
Tehnicki Vjesnik | Year: 2012

The Laboratory for Precise Measurement of Length, which is at the same time the Croatian National Laboratory for Length (in text Laboratory) takes part in CIPMMRA(Comité International des Poids et Mesures, Mutual Recognition Arrangement) comparisons of length standards, which include line scales as very important standards of length.When the results reported in the comparisons, it is necessary to state the estimated measurement uncertainty. Recently, the Monte Carlo simulations (MCS) have been increasingly applied in the field of estimation measurement uncertainties. The paper presents validation of the realised measurement uncertainty by GUM method in process of precise line scales calibration using the MCS method. The MCS method is based on random number generation from the probability density functions for each input value and forming of experimental probability density function of the output value. Also, the paper presents obtained results of the international comparison measurement which representing a real validation of the device and evaluated measurement uncertainty. Source

Mihalic T.,University of Zagreb | Medic S.,Karlovac University of Applied science | Kondic Z.,Varazdin University of Applied science
Tehnicki Vjesnik | Year: 2013

The improvements of the characteristics of centrifugal pump were investigated in this work experimentally and with computational fluid dynamics (CFD) analysis of the influence of adding vortex rotor to centrifugal one. The idea behind that improvement is in creating the so-called coherent structures of eddies and turbulence in the peripheral area of the vortex rotor mounted at the back side of centrifugal rotor. Research on the energy transformations in the centrifugal vortex pump in this work was carried out using control volume method for simulations of the flow in the centrifugal and the centrifugal vortex pump, and also by taking measurements of relevant parameters that describe the performance of pumps at their physical models. The measurement results were used as experimental validation and verification of numerical simulations; in contrast, flow visualization derived from the numerical simulation was used to interpret measurements. In deriving that experimental procedure, special care was taken with the flow measurements. The reason for this is in the fact that the flow measurements had the biggest influence on the overall measurement uncertainty. However, flow measurements were the most demanding with regard to experiment design and in taking the measurement readings. This experimental - CFD research made it possible to undertake an assessment of vortex rotor contribution on the head of centrifugal vortex pump. The influence of the vortex rotor on the efficiency of the centrifugal vortex pump was studied in contrast to the efficiency of a centrifugal pump with the same geometry. An analysis of the structure of flow was conducted in order to better understand the energy transformations that are the result of interaction between vortex rotor and the flow from the channels of centrifugal part of centrifugal vortex rotor. Source

Vyroubal D.,Karlovac University of Applied science | Lackovic I.,University of Zagreb
SAS 2015 - 2015 IEEE Sensors Applications Symposium, Proceedings | Year: 2015

Target temperature effect on eddy current displacement sensing is analyzed and evaluated by simulation. The equivalent target quality factor is detected as the main factor that, along with the probe equivalent quality factor, determines this effect. It manifests in ambiguity of displacement measurement, as well as, masking the displacement variation by target temperature variation, and vice versa. The analysis and the simulation show that there is an optimal operating frequency for minimum sensitivity over an acceptable displacement range. © 2015 IEEE. Source

Jankovic A.,General Hospital Karlovac andrije Stampara 3 | Korac Z.,General Hospital Karlovac andrije Stampara 3 | Bozic N.-B.,General Hospital Karlovac andrije Stampara 3 | Stedul I.,Karlovac University of Applied science
Injury | Year: 2013

We evaluated the incidence and aetiology of anterior knee pain (AKP) in a series of patients that underwent intramedullary nailing for stabilisation of tibial fractures. During the preparation of the entry site no excision of the infrapatellar fat was allowed and electrical haemostasis was kept at the lowest level. Medullary canal was reamed and the nails inserted in position of knee flexion over 100 degrees. All fractures were fixed using medial paratendinous approach. Functional outcome was measured using Lysholm knee score. The knee range of movement and return to previous level of activity were also documented and analysed. Mean follow up was 38.9 months (range 12-84 months). In total 60 patients with 62 tibial shaft fractures were analysed. The mean age at the time of final follow up was 49.4 years (range 20-87). In 22 (35.5%) a newly developed and persisting pain in the anterior region of the operated knee was reported. According to VAP scale, the pain was mild (VAS 1-3) in 12 cases (19.4%) and moderate (VAS 4-6) in 10 (16.1%). In 16 cases (73%) the pain was noticed 6-12 months after injury and subjectively related to return to full range of working and recreational activities. The mean Lysholm knee score in the group without AKP was 90.8. In the AKP group with mild pain it was 88.4 and in the group with moderate AKP it was 79.9. Complete return to previous professional and recreational activities occurred in 49/60 patients (81.7%). Content with the treatment regarding expectations in recovery dynamics and return to desired level of activity was present in 98.3% of patients; one patient was unsatisfied with the treatment. Our results indicate that respecting the physiological motion of Hoffa pad and menisci during knee flexion, accompanied with atraumatic mobilisation of retrotendinous fat, reduces incidence and severity of anterior knee pain following intramedullary fixation of tibial shaft fractures. © 2013 Elsevier Ltd. Source

Horvat D.,University of Zagreb | Ilijic S.,University of Zagreb | Kirin A.,Karlovac University of Applied science | Narancic Z.,University of Zagreb
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Within the framework of the extended teleparallel gravity, a new class of boson stars has recently been constructed by introducing the nonminimal coupling of the scalar field to the torsion scalar. An interesting feature of these static, spherical, self-gravitating configurations of the massive complex scalar field is their central region with outwardly increasing energy density, surrounded by a thick shell within which the joining with the usual asymptotically Schwarzschild tail takes place. In this work we extend the original model with the U(1) gauge field and we find that the combined effect of the charge and coupling of the field to torsion leads to a significant increase of the maximal mass and the particle number that can be supported against gravity. We also show that some charged configurations preserve the property of having the outwardly increasing energy density over the central region, regardless of the fact that charging the configurations affects the anisotropy of the pressures in the opposite way relative to that of the field-to-torsion coupling terms. © 2015 American Physical Society. Source

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