Finite-time stability analysis of fractional order time-delay systems: Gronwall's approach

In this paper, a stability test procedure is proposed for linear nonhomogeneous fractional order systems with a pure time delay. Some basic results from the area of finite time and practical stability are extended to linear, continuous, fractional order time-delay systems given in state-space form. Sufficient conditions of this kind of stability are derived for particular class of fractional time-delay systems. A numerical example is given to illustrate the validity of the proposed procedure

Vrednosti osnovnih hematoloških parametara u perifernoj krvi radnika izloženih uticaju para žive

In the present study was assessed the influence of occupational exposure to mercury vapours on the basic haematological parameters (erythrocyte, leukocyte and platelet count, haemoglobin concentration, haematocrit, MCV, MCH and MCHC). Studies were carried out on 138 workers involved in the production of chlorine using the mercuric electrolysis method (divided into three groups: permanently, periodically and earlier exposed to mercury vapours), as well as on 38 healthy workers. The shift time - weighted averages for mercury was determined in the workplace air before research; mean value was significantly over maximum tolerated dose. The mercury content in the blood and urine of exposed workers was determined by atomic absorption spectrophotometry. In all three groups 95th percentile values of mercury in blood and urine are significantly over MTD. Peripheral blood cell parameters were determined using an automatic cell counter. In the group exposed to mercury vapours, was found a statistically significant increase of erythrocyte count with a concomitant decrease in MCV. The mean values of haemoglobin concentration, MCHC and platelet count were higher in the group of workers exposed to mercury vapours, but the difference was not statistically significant. There were no significant differences in haematocrit, MCH and leukocytes between the studied groups. Our results indicate that long-term and permanent exposure to mercury vapours induces changes in the important haematological parameters of the peripheral blood.U radu je ispitivan uticaj izloženosti parama žive iz radne sredine na osnovne hematološke parametre (broj eritrocita, leukocita i trombocita, koncentraciju hemoglobina, hematokrit, MCV, MCH i MCHC). U studiju je uključeno 138 radnika koji rade u proizvodnji hlora procesom elektrolize (podeljeni su u tri grupe: stalno izloženi, povremeno izloženi i ranije izloženi uticajima para žive), kao 38 zdravih radnika. Pre studije su određene koncentracije žive u vazduhu radne sredine; srednje vrednosti su bile znatno iznad maksimalne doze tolerancije (MTD). Koncentracije žive u krvi i urinu radnika koji su izloženi živi određena je atomskom apsorpcionom spektrometrijom. U sve tri grupe je vrednost 95-tog percentila bila znatno iznad MTD. Hematološki parametri su određeni uz pomoć automatskog brojača. U grupi koja je stalno izložena parama žive, dobijeno je značajno poveć anje srednje vrednosti broja eritrocita, kao i značajno smanjenje vrednosti MCV. Srednje vrednosti koncentracije hemoglobina, MCHC i broja trombocita u grupi radnika koji su stalno izloženi uticaju žive bile su viće nego u kontrolnoj grupi, ali ta razlika nije statistički značajna. Između posmatranih grupa nije bilo značajne razlike u vrednostima hematokrita, MCH i broja leukocita. Dobijeni rezultati pokazuju da dugotrajna i stalna izloženost parama žive može da dovede do promena u vrednostima važnih hematoloških parametara

Numerical modeling of impact damages in aeronautical structures

У току експлоатације ваздухоплова могу се јавити и ударна оштећења структуралних елемената насталихударом страног тела и изазвати озбиљна оштећења.Дисертацијом су обухваћене савремене методе моделирања ударних оштећења које се базирају на комбинованој примени метода развијених теоријским, експерименталним и нумеричким средствима.Нумеричкимметодама су анализирани различити типови удара. Дефинисани нумерички модели су примењени за анализу нормалних и косих удара пројектила различитих облика врхова о челичне, алуминијумске и сендвич структуре за широки интервал брзина удара. За извршене анализе коришћене су различите дебљине препрека (Weldox челична плоча од 6 до 20 mm, aлуминијумска од 10 до 25 mm). Комбиновањем нумеричке анализе, теоријских резултата и експерименталних испитивања остварен је шири увид у процесе који сe дешавају при ударним оштећењима на различитим структурама ваздухоплова. Представљена метода за симулацију балистичког утицаја на керамичко-металне препреке, пружа могућности за брз прорачун балистичких граничних брзинаизлазних брзина, те се показала као користан алат за пројектовање керамичко-металне сендвич структуре. У току истраживања примењене су нумеричке методе засноване на методи коначних елемената (МКЕ) и методи која се заснива на спрези методе хидродинамике глатких честица и методе коначних елемената (СФМ). Обе методе могу да предвиде одговарајуће облике лома, природне брзине пројектила и балистичке граничне брзине у поређењу са онима запаженим у претходно објављеним анализама за случајеве удара различитих облика врхова пројектила, при чему постоје границе примене једне и друге методе. Спроведена су експериментална испитивања ради утврђивање узрока оштећења (прелома) звездастог сепаратора виталног дела структуре двоцевног ваздухопловног топа, који се догодио у току дејства. За добијање резултата коришћене је метода коначних елемената (МКЕ), нумеричке анализе, мерење тврдоће, мерење енергије удара, хемијска анализа и фрактографска испитивања.During the aircraft exploitation serious damage may appear as a consequence of a foreign body impact. In this dissertation modern methods for modeling of impact, based on the combined use of methods developed by theoretical, experimental and numerical means are researched. Different types of impacts are numerically analyzed. The defined numerical models are applied in analysis of normal and oblique impacts of steel, aluminium and sandwich structures by projectiles with different nose shapes and for a wide impact velocity interval. In the analysis different barrier thickness is used (Weldox steel plate from 6 to 20 mm, aluminium plate from 10 to 25 mm). Combining the numerical analysis, theoretical results and experimental investigations a wider insight in the impact damage processes of different aircraftstructures is achieved. The presented method for simulation of the ballistic influence on ceramic/metal barriers provides the possibility for fast computation of the ballistic limitand residual velocities and therefore proved to be a useful tool for design of ceramic/metal sandwich structures. During the research numerical methods based on the finite element method (FEM) and the coupling of FEM and the smoothed particle hydrodynamics method (SPH) have been used. Both methods can predict the fracture shapes, residual velocities and ballistic limits in comparison with results observed in previously published analysis for cases of impacts with different projectile nose shapes, wherein there are limitations of the use of one or the other method. Experimental investigations are conducted in order to determine the cause of damage(fracture) of a star separator, vital part a double pipe aerial cannon, which happened during the cannon operation. For obtaining the results finite element method (FEM), hardness measurements, impact energy measurements, chemical analysis and fractografic investigations are used

Colloid electrohydrodynamics

This brief extracted review presents the recent development in basic and applied science and engineering of finely dispersed particles and related systems in general, but more profound and in-depth treatise are related to the liquid-liquid finely dispersed systems, i.e. emulsions and double emulsions. Twenty-five years ago, the idea, at first very fogy, came out from the pilot plant experiments related to the extraction Of uranium from wet phosphoric acid. In particular the solution of the entrainment problems, breaking of emulsions/double emulsions, as the succession of the extraction and stripping operations/processes, was performed In this pilot plant, secondary liquid-liquid phase separation loop was designed and carried out. The loop consisted of a lamellar coalescer and four flotation cells in series. Central equipment in the loop, relevant to this investigation, was the lamellar coalescer. The phase separation in this equipment is based on the action of external forces of mechanical and/or electrical origin, while adhesive processes at the inclined filling plates occur. Since many of related processes, e.g. adhesive processes, rupture processes and coalescence, were not very well understood, deeper research of these events and phenomena was a real scientific challenge

Fatty acid profile in muscles of carp (cyprinus carpio l.) Raised in a semi-intensive production system fed with grains, pelleted and extruded feed

The effects of grains, pelleted and extruded feed on the fatty acid content in carp meat has not been examined yet. In this work, we present evidence that the high carbohydrate content in all three types of feed causes oleic acid to predominate in all meat samples. A higher PUPA content in the meat of fish fed with granulated feed was detected. The extruded feed diet led to 69% greater n-3, and 53% lower n-6 fatty acid contents. Their ratio is thus 2.64-fold higher than in meat of carp fed with pelleted feed. A higher content of n-3 fatty acids in fish fed with extruded feed was the consequence of higher DNA (1.6 times) and EPA (3.3 times) contents. The detected differences could be the consequence of the thermal treatment of extruded feed that makes the proteins, carbohydrates and lipids more accessible to fish than in a pelleted feed

Uticaj endotelina i L-NAME na koncentraciju mokraćne kiseline i uree u plazmi kod Wistar pacova

Effects of endothelins, which include vasoconstriction and vasodilatation are possible by different molecular mechanisms. Endothelins induce increased synthesis of nitric oxide which in turn inhibits the synthesis of endothelin. Changes in biochemical parameters connected with the increased and decreased synthesis of nitric oxide are not thoroughly examined yet. In a series of experiments we compared the effects of endothelin (ET-1) on the inhibition of nitric oxide synthase (NOS), as well as the effects of L-nitro arginin metal estar (L-NAME) on plasma urea and uric acid concentration. Experiments were performed on anesthetized female adult Wistar rats. The experimental groups received an i. v. bolus of ET-1, L-NAME or saline. All parameters, heamodynamic and biochemical, were measured before the animals were sacrificed. L-NAME increased the mean arterial pressure, decreased renal blood flow and increased vascular resistance in carotid and renal arteries and increased in plasma uric acid and urea concentrations. ET- 1 significantly decreased uric acid concentration in the plasma but did not effect plasma urea concentration compared to the control group. These differences show complex relations of nitric oxide with cellular signalization compared to the basic NO-cGMP pathway.Efekti endotelina koji uključuju vazokonstrikciju I vazodilataciju ostvaruju se različitim molekularnim mehanizmima. Endotelin indukuje povećanu sintezu azotnog oksida za koji se smatra da povratno inhibira sintezu endotelina. Promene biohemijskih parametara vezanih za povećanu i smanjenu sintezu NO nisu dovoljno proučene. U ovom radu su upoređeni efekti endotelina (ET-1) i inhibitora NOS-a, L-NAME na koncentraciju mokraćne kiseline i uree u plazmi. Eksperimenti su izvedeni na anesteziranim odraslim NW pacovima, ženskog pola. Eksperimentalne životinje su u i.v. bolusu primale ET-1, L-NAME ili fiziološki rastvor. Svi hemodinamski i biohemijski parametri su mereni pre žrtvovanja. L-NAME dovodi do povećanja srednjeg arterijskog pritiska smanjenja renalnog protoka i povećanja vaskularnog otpora u karotidnoj i renalnoj arteriji i povećanja koncentracije mokraćne kiseline i uree u plazmi. ET-1 značajno smanjuje koncentraciju mokraćne kiseline u plazmi ali ne utiče na koncentraciju uree u odnosu na kontrolu. Ove razlike pokazuju kompleksnije relacije NO-a sa ćelijskom signalizacijom u odnosu na osnovni NO-cGMP put

Ageing-induced changes of reduced and oxidized glutathione in fragments of maize seedlings

A trial with four maize inbred lines with the ability to have different durations of seed germination in the course of the accelerated ageing (AA) treatment was set up. Changes of the content of total, reduced and oxidized glutathione (expressed as monomers) were observed in the seeds and seedlings before and after the treatment. For the first time, changes of glutathione in whole seedlings, as well as in the rest of the seed, were analyzed. It was noticed that maize in breds with a smaller decrease of the total glutathione but with an increase of the oxidized form had the ability of prolonged germination. In the control seed- lings, the amount of total glutathione was lower than in the treated ones. Maize seeds which lost germination faster had greater losses of total glutathione with an increased content of the oxidized form in seedlings. The ability of prolonged germination together with the possibility of glutathione synthesis in seedlings are genotypic traits.Postavljen je ogled sa četiri linije kukuruza različite dužine očuvanja klijavosti semena tokom tretmana ubrznog starenja. Ispitivane su promene ukupnog, kao i redukovanog i oksidovanog glutationa (izraženi kao monomeri) u semenu i klijancima pre i nakon ubrzanog starenja. U istraživanjima su prvi put analizirane promene glutationa u celim klijancima, kao i ostatku semena. U semenu linija kukuruza koje imaju sposobnost dužeg očuvanja klijavosti bio je manji gubitak ukupnog glutationa, uz povećanje udela oksidovanog oblika. Kod njihovih klijanaca došlo je do povećanja sadržaja ukupnog glutationa u odnosu na kontrolne klijance. Seme kukuruza koje brže gubi klijavost imalo je veće gubitke ukupnog glutationa, uz veći sadržaj oksidovanog oblika kod formiranih klijanaca. Dužina očuvanja klijavosti, kao i sinteza glutationa kod klijanaca je genotipska osobina.nul

Green living roof implementation and influences of the soil layer on its properties

Affected by undeniable climatic change, the temperature of the urban areas rises continually, increasing rapidly the energy problem of cities and amplifying the pollution problems. The thermal stress is increased, thus both the indoor and the outdoor thermal comfort levels are decreased, enhancing the health problems. Green roof implementation in the building envelope is strategy that provides heat island amelioration, thermal comfort for occupants and reduces energy consumption of buildings. Green living roofs are a passive cooling technique, which can stop the incoming solar radiation from reaching the building structure below. In this paper, we assessed the importance of the green roofs in providing environmental and building energy benefits, and brief investigation on the different configuration of the soil layer in the green roof assembly influences to the temperature of the roof surface was presented. Investigation was conducted for first phase of the living roof growth. Four cells were designed in Solid Works software where the transient thermal study was performed in order to determine differences between the behavior of the conventional roof and three green roof types

Green living roof implementation and influences of the soil layer on its properties

Affected by undeniable climatic change, the temperature of the urban areas rises continually, increasing rapidly the energy problem of cities and amplifying the pollution problems. The thermal stress is increased, thus both the indoor and the outdoor thermal comfort levels are decreased, enhancing the health problems. Green roof implementation in the building envelope is strategy that provides heat island amelioration, thermal comfort for occupants and reduces energy consumption of buildings. Green living roofs are a passive cooling technique, which can stop the incoming solar radiation from reaching the building structure below. In this paper, we assessed the importance of the green roofs in providing environmental and building energy benefits, and brief investigation on the different configuration of the soil layer in the green roof assembly influences to the temperature of the roof surface was presented. Investigation was conducted for first phase of the living roof growth. Four cells were designed in Solid Works software where the transient thermal study was performed in order to determine differences between the behavior of the conventional roof and three green roof types