Komparativna analiza i optimizacija T i I poprečnih preseka dizalične kuke primenom dva algoritma inspirisana fizikom

This paper presents analysis and optimization of the geometric parameters of T and I cross-sections of crane hook, observed for the most critical location of its structure. The reduction of the cross-sectional area of crane hook was set as the goal in this study. The stresses at characteristic points of the most critical cross-section are taken as constraint functions, calculated according to Winkler-Bach theory, and some geometric conditions are set, too. Two metaheuristic algorithms based on the laws of physics, Charged System Search (CSS) algorithm and Thermal Exchange Optimization (TEO) algorithm, were selected for optimization methods, using by MATLAB software package. The goal of this research is to show that the proposed cross-sections give significant savings in comparison to standard crane hook, wherein the one standard capacity was observed. Both observed cross-sections were analyzed in two variants, and the comparison of their optimization results was performed to show which one achieves the best results. Also, the comparison of the applied optimization algorithms was performed.Publishe

Primena metode konačnih razlika kod određivanja ugiba nosača kontinualno promenljivog poprečnog preseka

Amongst others, the deformation criterion is to be fulfilled in the process of steel structure design. Often, it can be more restrictive than the stress criterion. Although the stress state is within the permissible limit, excessive structure deformation can lead the additional load to emerge in the carrying structure and cause improper operation and shorter life of attached devices and equipment. For that reason, besides other requirements, the allowable deformation limits of the steel carrying structure are defined. The stress-strain analysis of the structure is usually conducted by utilization of finite element method (FEM) in the early phase of the design process. Alternatively, this paper shows the application procedure of the finite difference method (FDM) for the deflection determination on the simple elastically restrained cantilever beam with continuously varying box-like cross-section and linear change of section height. Dependence of the deflection on the design parameters is obtained through programming in MATLAB and the comparison is made with the results from the finite element model built in ANSYS. The results from both numerical approaches showed excellent compliance.Publishe

Stabilnost i optimizacija stuba dizalične staze

This research has presented the built-up column analysis with batten, applied to crane runaway support, where stability is put in the foreground. Also, optimization of all essential geometrical parameters of the built-up column was performed for a given height of the crane column and changing the load capacity. The chord members were composed of as-welded I-sections instead of fabricated hot rolled sections witch are commonly used in these constructions. The mass of the built-up columns, which consists of the chord and Web members (battens) members, was taken as the goal function in this research. Additional stability and load capacity conditions were used as constraint functions, as well as specific design recommendations. The optimization procedure was performed in the Ms. EXCEL software package, using the GRG2 algorithm because certain benefits are essential in this optimization problem. In this way, the justification of applying the proposed model of calculation and optimization was shown because the necessary geometrical parameters can be reached very quickly when designing these types of structures, considering that there are a large number of variables and constraint functions. It is also shown how the mass of the column changes and the optimal geometric parameters when the compression force on the column of the runaway crane support increases.Publishe

Aksijalno-radijalni ležaj kao segment veze okretne platforme sa nosećom konstrukcijom

The paper presents the connection of rotating platforms in building and transport machines depending on the type of driving mechanism. A special attention is paid to axial-radial bearings having big diameters made by prominent manufacturers. There are some necessary conditions which have to be met by supporting frames because working capacity of the bearings depends on them. Also, the law of distribution of load of moment of external forces is proposed because it provides identification of maximum load as a starting basis for further research on determination of optimal laws of distribution of acting forces which are caused by the moment of forces.Publishe

Prilog analizi krutosti ramova utovarno-istovarnih kolica pretovarnih mosnih dizalica

The paper analyzes the dependence of the stiffness of the support frames of the cranes with loading-unloading trolley on the change of geometrical parameters of the frames. The calculation model of the frames with transverse stiffness was formed because it additionally stiffens the supporting surface of the frames for connection with the axial-radial bearing. The relations of characteristic geometrical sizes of longitudinal and transverse elements were established, at which the necessary stiffness of the frames of loading-unloading trolley was achieved. Also, the variables and constants of geometric size were introduced, as well as the constant values of appropriate coefficients, the variation of which provides the possibility to form the optimal structure of the frames of loading-unloading trolley.Publishe

Decolorization of reactive black 5 using dielectric barrier discharge in the presence of inorganic salts

Inorganic salts improve the coloration of textiles, which increase pollution load on dyehouse effluent in general. Decolorization of reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film Dielectric Barrier Discharge (DBD). Initial dye concentration in the solution was 40.0 mg L-1. The effects of addition of inorganic salt different high concentrations (NaCl, Na2SO4 and Na2CO3) on the degree of decolorization were studied. Recirculation of dye solution through the DBD reactor with applied energy density 45-315 kJ L-1 was used. The influence of residence time was investigated after 5 minutes and 24 hours of plasma treatment. Decolorization of the dyes was monitored by spectrophotometric measurement. Changes of pH values and the conductivity of dye solution after each recirculation were tested. The most effective decolorization of over 90% was obtained with the addition of NaCl (50 g L-1), applied energy density of 135 kJ L-1 and after residence time of 24 hours of plasma treatment. Decolorization of solutions containing inorganic salts Na2SO4 and Na2CO3 were lower than for the solution without salt

The impact of resistance training program on the muscle strength and bone density in adolescent athletes

© 2018 Saša Bubanj et al., published by Sciendo 2018. Strength training and other modes of physical activity may be beneficial in osteoporosis prevention by maximizing bone mineral accrual in childhood and adolescence. This study focuses on the impact of the nine-month long program of resistant exercises with different level of external loads (low, middle and high) on the lower limbs explosive strength and bone tissue density in athletes adolescents aged 17 to 18 years. Sixty healthy, male athletes and non-athletes, divided into experimental (ES, sprinters, N = 45) and control sub-sample (CS, non-athletes, N = 15), were included in study. ES examinees (EG1, EG2 and EG3) were subjected to the program of resistance exercises with low level (60% of the One Repetition Maximum-1RM), middle level (70% 1RM), and high level (85% 1RM) of external loads, respectively. Bone Density values were determined by the use of a clinical sonometer.,Sahara (Hologic, Inc., MA 02154, USA). Explosive strength values of hip extensors and flexors, knee extensors and flexors, and ankle plantar and dorsiflexors were determined by the use of accelerometer.,Myotest (Sion, Switzerland) and the means of Counter Movement Jump without arms swing (CMJ) and half squat. ANOVA method for repeated measures and ANCOVA method were used to determine significant differences and resistance program effects on the lower limbs explosive strength and bone tissue density. Resistance exercise does impact the explosive strength and bone parameters in a way to increase half squat 1RM values, but decreases CMJ values, and increases speed of sound (SOS), broadband ultrasound attenuation (BUA) and bone mineral density (BMD) values in athletes-adolescents, aged 17-18 years

Spatial distribution of major and trace elements in artificial lakes in Serbia: health risk indices and suitability of water for drinking and irrigation purposes

Lakes and reservoirs are the main water resources for household, irrigation, and industrial use. Hence, it is necessary to control water pollution and have reliable information on water quality, which refers to its suitability for a particular purpose. The main objective of this study was to evaluate the suitability of water for drinking and irrigation purposes from ten artificial lakes on the territory of the Republic of Serbia. The physicochemical parameters were determined using standard analytical methods, whereas the optical emission spectrometry with inductively coupled plasma, ICP-OES, was used to determine the concentrations of 23 macro-, micro-, and trace elements in water. Health risk indices of drinking water and its suitability for irrigation purposes were evaluated. The results of physicochemical parameters, except for total organic matter, indicated that most samples were within the recommended values. Among analyzed elements, the concentration of Mg was elevated in the water of the lakes Srebrno and Prvonek. The results of health risk assessment clearly showed that there was no acute health risk (HQA < 1), whereas long-term risk (HQL) in the studied lakes was observed with respect to As (lakes Grlište and Srebrno), Mn (lakes Srebrno and Prvonek), Ni (Lake Vrutci), and Sr (Lake Grlište). The irrigation criteria indicated that the water from the examined lakes had satisfactory quality for this purpose, except for residual sodium carbonates (RSC). This criterion indicated low quality or unsuitability of the water in 7 lakes. The main outcomes provided valuable information on the suitability of water from the artificial lakes for intended uses

Impedance analysis of milk quality using functionalized polyamide textile-based sensor

Present paper demonstrates design and characterization of a textile based microfluidic chip sensor for the detection of milk adulteration through measuring the real part of the impedance and impedance phase angle. Polyamide (PA) based textile fabric was chemically functionalized with polyaniline and titanium dioxide nanoparticles (PANI/TiO2) nanocomposite and embedded in the microfluidic chip. Prototyping of microfluidic chip was performed by xurography and hot lamination using polyvinyl chloride foils. Morphological and chemical properties of fabricated textile-based PA-PANI/TiO2 chip sensor were evaluated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Quality of milk was accessed with fabricated textile sensor using cow and goat milk samples. The electrochemical impedance spectroscopy (EIS) was applied to detect the change in resistance and phase angle of pure and diluted milk. The developed PA-PANI/TiO2 chip sensor acted as a variable resistor that was able to identify adulterations and spoilage of the milk samples with sensitivity of 0.06 degrees of phase angle variation per % of water dilution. Our work promises that application of textile electronics could be efficiently exploited for food safety, point-of-care and environment monitoring applications

Synthesis, Characterization, and Cytotoxicity of a Novel Gold(III) Complex with O,O-Diethyl Ester of Ethylenediamine-N,N-Di-2-(4-Methyl)Pentanoic Acid

A novel gold(III) complex, [AuCl2{(S,S)-Et(2)eddl}]PF6, ((S,S)-Et(2)eddl = O,O-diethyl ester of ethylenediamine-N,N-di-2-(4-methyl)pentanoic acid) was synthesized and characterized by IR, 1D (H-1 and C-13), and 2D (H,H-COSY and H,H-NOESY) NMR spectroscopy, mass spectrometry, and elemental analysis. Density functional theory calculations confirmed that (R,R)-N,N diastereoisomer was energetically the most stable isomer. In vitro antitumor action of ligand precursor [(S,S)-H(2)Et(2)eddl]Cl-2 and corresponding gold(III) complex was determined against tumor cell lines: human adenocarcinoma (HeLa), human colon carcinoma (LS174), human breast cancer (MCF7), non-small cell lung carcinoma cell line (A549), and non-cancerous cell line human embryonic lung fibroblast (MRC-5) using microculture tetrazolium test (MTT) assay. The results indicate that both ligand precursor and gold(III) complex have showed very good to moderate cytotoxic activity against all tested malignant cell lines. The highest activity was expressed by [AuCl2{(S,S)-Et(2)eddl}]PF6 against the LS174 cells, with IC50 value of 7.4 +/- 1.2 mu M