Potential for improvement of comfort parameters in off-road vehicles of Serbian armed forces

The paper presents the comparative results of comfort parameter testing inside the cabin of Land Rover Defender off-road vehicles. The measurements were carried out on two vehicle models -110 GS Hard Top and 110 GS Soft Top Heavy Duty. Tests on comfort parameters were performed only on the military off-road vehicles, or to be more precise on the military off-road vehicles used by the Serbian Armed Forces. The results of the performed tests offer some suggestions for the improvement of comfort of military off-road vehicles used by the Serbian Armed Forces. The comfort elements have been compared from the aspect of accommodation of the crew, noise, vibrations and heating efficiency. A part of the experiment was performed by intensive driving of these off-road vehicles in real world conditions, on three pre-selected types of terrain surface, in order to ensure the repeatability of the testing results: heath, gravel and asphalt base (a portion of the Belgrade-Zagreb highway at the territory near Sid was used due to its less frequent traffic and surface quality). Noise and vibration measurements were carried out at the driver's seat, co-driver's seat and other passenger seats under strictly defined vehicle speeds. Testing of the heating efficiency inside the cabin was carried out under laboratory conditions in the cold chamber of the artillery range at Nikinci at a constant ambient temperature of -16 degrees C

Potential for improvement of comfort parameters in off-road vehicles of Serbian Armed Forces

U radu su prikazani usporedni rezultati ispitivanja parametara udobnosti u kabini terenskog automobila Land Rover Defender. Mjerenja su provedena na dvije varijante vozila 110 GS Hard Top i 110 GS Soft Top – heavy duty. Testiranja parametara udobnosti obavljena su samo na vojnim terenskim vozilima, ili još preciznije, na terenskim vozilima koja su u uporabi u Vojsci Srbije. Rezultati obavljenih testiranja nude neke prijedloge za poboljšanje udobnosti vojnih terenskih vozila koja se koriste u Vojsci Srbije. Uspoređeni su elementi udobnosti s aspekta smještaja posade, buke, vibracija i efikasnosti grijanja. Dio eksperimenta je obavljen u realnim eksploatacijskim uvjetima, prilikom intenzivne vožnje terenskih vozila na tri odabrane opitne staze, kako bi se osigurala ponovljivost rezultata ispitivanja: ispresijecana ledina (Deliblatska peščara), ravničarski makadam (Fruška gora) i asfaltna podloga (dionica autoputa Beograd – Zagreb pored Šida zbog manje frekvencije saobraćaja i kvalitetne podloge). Mjerenja buke i vibracija su obavljena na mjestima vozača, suvozača i članova posade pri strogo definiranim brzinama gibanja vozila. Ispitivanje efikasnosti grijanja u kabini obavljeno je u laboratorijskim uvjetima u hladnoj komori poligona Nikinci pri konstantnoj temperaturi okoline od -16 °C.The paper presents the comparative results of comfort parameter testing inside the cabin of Land Rover Defender off-road vehicles. The measurements were carried out on two vehicle models – 110 GS Hard Top and 110 GS Soft Top Heavy Duty. Tests on comfort parameters were performed only on the military off-road vehicles, or to be more precise on the military off-road vehicles used by the Serbian Armed Forces. The results of the performed tests offer some suggestions for the improvement of comfort of military off-road vehicles used by the Serbian Armed Forces.The comfort elements have been compared from the aspect of accommodation of the crew, noise, vibrations and heating efficiency. A part of the experiment was performed by intensive driving of these off-road vehicles in real world conditions, on three pre-selected types of terrain surface, in order to ensure the repeatability of the testing results: heath, gravel and asphalt base (a portion of the Belgrade – Zagreb highway at the territory near Šid was used due to its less frequent traffic and surface quality). Noise and vibration measurements were carried out at the driver’s seat, co-driver’s seat and other passenger seats under strictly defined vehicle speeds. Testing of the heating efficiency inside the cabin was carried out under laboratory conditions in the cold chamber of the artillery range at Nikinci at a constant ambient temperature of -16 °C

Fem analysis of pressure vessel with an investigation of crack growth on cylindrical surface

To ensure reliability of pressure vessels during service it is necessary to (1) know properties of materials used in their design and (2) evaluate vessels' behaviour under different working conditions with satisfying accuracy. Due to various technical and/or technological requirements, nozzles are usually welded on vessel's shell producing geometrical discontinuities that reduce the safety factor. To evaluate their influence, vessels with two different nozzles were experimentally studied and critical areas for crack initiation have been identified by 3D Digital Image Correlation (DIC) method. After that, the numerical analysis of equivalent 3D finite element model was performed and obtained results were compared with experimental values. In the most critical area, next to the one of the nozzles, crack was initiated and then growth of the damage was simulated using extended finite element method (XFEM). In this paper evaluation of stress intensity factors (SIFs) along crack path is presented, as well as the most probable direction of the crack propagation on the shell. Based on SIFs values, critical length of the crack and number of pressure cycles to the final failure were estimated

Analysis of Comfort Parameters in Special Purpose Vehicles from Technological Development Point of View

The analysis of comfort parameters in the crew cabin space of two variants of the special purpose off-road vehicle is presented, taking technological development aspects into account. Tests of noise, vibration and heating - cooling efficiency have been performed in realistic operating conditions, during the intensive driving on three selected test tracks, in order to ensure the repeatability of the obtained results. Measuring of noise and vibration levels at the drivers, co-drivers and crew members' seats were performed at strictly defined vehicle speed. Heating efficiency tests for the cabin have been performed in laboratory conditions, inside a cold chamber with the constant temperature of (-16 degrees C), whereas cooling efficiency tests were conducted in the hot chamber at the temperature of (+ 40 degrees C). The results of these tests enable the selection of a more comfortable variant of vehicle, wherein the one with less seats for passengers in the cabin which, in addition to more comfort also has the advantage of greater storage space, and from the application flexibility standpoint, which is offered by the possibility of transporting more passengers and less load, such vehicles offer better environment control from within the vehicle

Још једном о словенском *gotovъ

Након прегледа досадашњих покушаја тумачења псл. придева *gotovъ ‘promptus, paratus, fi nitus’, аутори просуђују да је Трубачовљево извођење од супина на -t(e)u-, пореклом од пие. *gu ̯ ā-/*gu ̯ ă- ‘ићи’, једино перспектив- но и вредно даљег развијања. Прет постављају да у основи словенског придева лежи датив протерокинетичке глаголске именице, те ту творбу пореде са староиндијским participia necessitatis на -tavya-, евентуално и са грчким на -τέος, од датива пореклом од инфинитива на *-teu̯ei (> ведски -tave), чији је акценат првобитно био на суфиксалном слогу, чиме се објашњава нулска база у корену словенске речи.After a review of previous attempts to interpret the Common Slavic *gotovъ ‘ready, prepared, fi nished’, Trubačev’s etymology, which traces it back to a supine in -t(e)u- from PIE *gu̯ ā-/*gu̯ ă- ‘to go’, is judged to be the only promising explanation and is further developed by the authors. They assume that underlying the Slavic adjective there is the dative of a proterokinetic verbal noun and compare the derivation of OInd. participia necessitatis in -tavya-, perhaps also the Greek -τέος, from dative-based infi nitives in *-teu̯ei > Vedic -tave, with the stress originally laid on the suffi x syllable, which accounts for the zero-grade root vocalism of the Slavic word

Active hip orthosis for assisting the training of the gait in Hemiplegics

The gait restoration is a significant component of the rehabilitation of patients with hemiplegia after central nervous system lesion. The typical symptom of the disability is the lack of hip extension during the stance phase and hip flexion during the swing phase of the affected leg; therefore, asymmetry and perturbed balance while walking. We developed a new modular orthosis for assisting hip flexion and extension during the therapeutic sessions of the gait in hemiplegic individuals based on thorough analysis of the gait characteristics of normal gait. The system is designed to fit into the powered postural controller Walkaround®. The system is developed based on the estimation of torque and power requirement for the gait at speeds up to 1.1 m/s. The model used for the simulation is a known double pendulum in the sagittal plane. The kinematics and dynamics used as the input for the simulation have been recorded in the gait laboratory with eight cameras and force platforms. The system needs to be clinically evaluated before it possibly can be turned into innovation. © 2018, University of Kragujevac, Faculty of Science

Variability of Morphological Traits of European Beech (Fagus sylvatica L.) Seedlings in Serbia

The results of interpopulation variability of morphometric parameters of European beech (Fagus sylvatica L.) seedlings originating from eight populations from the part of natural distribution area in Serbia are presented in this paper. The studied populations of Dubašnica, Jastrebac, Boranja, Fruška Gora, Mali Pek, Goč, Beljanica, and Javor have various ecological and vegetational characteristics. The results of this paper refer to root collar diameter and height of seedlings at the age of 1+0 and 2+0. Analysis of variance showed a statistically significant difference between the populations in terms of the studied morphological traits of seedlings (p<0.01; α=0.05). Geographical differentiation of the studied populations has not been determined by applying cluster analysis, but the populations are grouped randomly and they indicate the ecotypic nature of beech genetic variation. The results of this research may serve in beech breeding and the available gene pool conservation. Based on the obtained results it can be recommended that in terms of transfer and use of the beech forest reproductive material greater attention should be paid to the ecological conditions of the parent stands and habitats where afforestation has been performed

Variability of Morphological Traits of European Beech (Fagus sylvatica L.) Seedlings in Serbia

The results of interpopulation variability of morphometric parameters of European beech (Fagus sylvatica L.) seedlings originating from eight populations from the part of natural distribution area in Serbia are presented in this paper. The studied populations of Dubašnica, Jastrebac, Boranja, Fruška Gora, Mali Pek, Goč, Beljanica, and Javor have various ecological and vegetational characteristics. The results of this paper refer to root collar diameter and height of seedlings at the age of 1+0 and 2+0. Analysis of variance showed a statistically significant difference between the populations in terms of the studied morphological traits of seedlings (p<0.01; α=0.05). Geographical differentiation of the studied populations has not been determined by applying cluster analysis, but the populations are grouped randomly and they indicate the ecotypic nature of beech genetic variation. The results of this research may serve in beech breeding and the available gene pool conservation. Based on the obtained results it can be recommended that in terms of transfer and use of the beech forest reproductive material greater attention should be paid to the ecological conditions of the parent stands and habitats where afforestation has been performed

Poređenje kinetike bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u destilovanoj vodi i fiziološkom rastvoru

The isothermal kinetics Curves of the swelling of a poly(acrylic acid) hydrogel in distilled water and physiological Solution at temperatures ranging from 20 to 40 degrees C were determined. The possibility of applying both the Fick's kinetics model anti kinetics model of the first order chemical reaction to the swelling kinetics of the PAA hydrogel in distilled water and physiological Solution were examined. It was found that the possibilities of applying these models were limited. The new model of the kinetics of swelling in distilled water and physiological solution was established. The kinetic parameters (E-a, ln A) for the swelling in distilled water and physiological solution were determined. The decrease of the equilibrium degree of swelling and the saturation swelling rate of the swelling of the PAA hydrogel in physiological solution compared to swelling in distilled water could be explained by the decreased differences in the ionic osmotic pressures between the hydrogel and the swelling medium. The increase of the initial swelling rate in the physiological solution might be caused by an increased density of charges at the network and by an increased affinity of the network towards the water molecules. The increase of the activation energy of the swelling of the PAA hydrogel in the physiological solution is a consequence of its additional "ionic crosslinking".U radu su ispitivane izotermalne kinetičke krive bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u destilovanoj vodi i fiziološkom rastvoru u temperaturnom opsegu od 20 do 40 °C. Ispitivana je mogućnost primene Fikovog kinetičkog modela kao i kinetike i reda hemijskih reakcija na kinetiku bubrenja poliakrilnog hidrogela.Utvrđeno je da su mogućnosti za njihovu primenu vrlo ograničene. Iz tih razloga primenjen je novi model kinetike bubrenja. Određeni su kinetički parametri (Ea, lnA) za procese bubrenja u destilovanoj vodi i fiziološkom rastvoru. Smanjenje ravnotežnog stepena bubrenja i saturacione brzine bubrenja hidrogela delimično neutralisane poli(akrilne) kiseline u fiziološkom rastvoru u odnosu na destilovanu vodu može se objasniti smanjenjem razlike u jonskom osmotskom pritisku između hidrogela i medijuma za bubrenje. Povećanje inicijalne brzine bubrenja u fiziološkom rastvoru u odnosu na destilovanu vodu prouzrokovano je povećanjem gustine naelektrisanja na polimernoj mreži i povećanim afinitetom prema molekulima vode. Povećanje energije aktivacije hidrogela delimično neutralisane poli(akrilne) kiseline pri bubrenju u fiziološkom rastvoru se objašnjava dodatnim "jonskim umreženjem" hidrogela u fiziološkom rastvoru