The combined method for uncertainty evaluation in electromagnetic radiation measurement

Electromagnetic radiation of all frequencies represents one of the most common and fastest growing environmental influence. All populations are now exposed to varying degrees of electromagnetic radiation and the levels will continue to increase as technology advances. An electronic or electrical product should not generate electromagnetic radiation which may impact the environment. In addition, electromagnetic radiation measurement results need to be accompanied by quantitative statements about their accuracy. This is particularly important when decisions about product specifications are taken. This paper presents an uncertainty budget for disturbance power measurements of the equipment as part of electromagnetic radiation. We propose a model which uses a mixed distribution for uncertainty evaluation. The evaluation of the probability density function for the measurand has been done using the Monte Carlo method and a modified least-squares method (combined method). For illustration, this paper presents mixed distributions of two normal distributions, normal and rectangular, respectively

Primena modifikovanih tanina u antikorozionim alkidnim premazima

The study of the synthesis of anticorrosive inhibitors, based on chemically modified tannins, and their use in alkyd based coatings to improve anticorrosive properties is presented in this work. Two methods of tannin modification were applied: direct method using ammonium hydroxide, ammonium hydroxide/ammonium chloride buffer or diethylenetriamine (DETA); and a two-step method including tannin modification with epichlorohydrin (ECH) in first step to produce epoxy modified tannin, ET, and further modification with heteroaromatic amines or linseed oil fatty acids (LFA) in second step. The obtained anticorrosive additives were characterized using ATR-FTIR, 1H and 13C NMR spectroscopies and elemental analysis. Epoxy, amino, hydroxyl, acid and iodine values of the synthesized inhibitors were determined according to standard methods. The prepared alkyd coating with tannin inhibitors was tested according to standard SRPS EN ISO 4628 method. Anticorrosive coating containing modified tannin based additive showed increased anticorrosive properties, good adhesion and coverage comparing to the coating with zinc phosphate additive. The alkyd coating films based on ET-LFA and ET modified with 2-amino-5- mercapto-1,3,4-thiadiazole showed best anticorrosive results.U ovom radu prikazana je sinteza antikorozionih aditiva na bazi hemijski modifikovanog tanina i njihova primena u alkidnim premazima u cilju poboljšanja antikorozionih svojstava. Prikazane su dve metode modifikacije tanina: direktna modifikacija tanina primenom amonijum-hidroksida, amonijum-hidroksid/amonijum-hlorid pufera ili dietilentriamina (DETA); i dvostepena modifikacija tanina koja u prvom stupnju uključuje modifikaciju epihlorhidrinom sa ciljem da se dobije tannin sa epoksi terminiranim funkcionalnim grupama, ET, i modifikaciju ET tanina sa heteroaromatičnim aminima ili masnim kiselinama izolovanim iz lanenog ulja (LFA) u drugom stupnju. Sintetisani antikorozioni aditivi su okarakterisani primenom ATR-FTIR, 1H i 13C NMR spektroskopija, i elementalnom analizom. Sadržaj epoksi, amino, hidroksilnih i karboksilnih grupa i vrednost jodnog broja sintetisanih aditiva određen je prema standardnim metodama. Alkidni premazi koji sadrže antikorozione aditive na bazi modifikovanog tanina ispitani su prema standardnoj SRPS EN ISO 4628 metodi. Antikorozivni alkidni premazi na bazi modfikovanih tanina pokazali su poboljšane antikorozione karakteristike i adheziju u poređenju sa alkidnim premazom na bazi cink-fosfata. Alkidni premazi koji sadrže dvostepeno modifikovani tanin sa LFA i 2-amino-5-merkapto-1,3,4-tiadiazolom pokazali su najbolje antikorozione karakteristike

The usage of 3D printing in the analysis of the product design: Case: Electronic enclosure of compact pressure transmitter

Aditivna proizvodnja uključuje izradu proizvoda složene geometrije u relativno malim količinama, kao i izradu alata i kalupa za masovnu proizvodnju. Aditivnom proizvodnjom realizuju se modeli prema digitalnom prikazu, a primena je ogromna u različitim industrijskim sektorima. U poređenju sa tradicionalnom proizvodnjom, glavni parametri u odabiru aditivne tehnologije su: ušteda energije, smanjenje otpada, smanjenje upotrebe većeg broja alata, kao i optimizacija dizajna. Aditivna proizvodnja ili tehnologija 3D štampe rade na principu dodavanja materijala u slojevima, tj. model se formira od slojeva rastopljenog materijala koji se odmah hladi i očvršćava. 3D štampa omogućava čestu i jednostavnu modifikaciju modela na zahtev kupca, a pre ulaska modela u samu proizvodnju. Ovo čini komunikaciju na relaciji proizvođač-kupac dosta jednostavnom. Polazni materijal za izradu modela je polilaktična kiselina (PLA). To je ekološki termoplastični poliester koji se prirodno razgrađuje u prirodi. Na mehaničke karakteristike realizovanog modela od PLA značajno utiču različite tehnološke promenljive kao što su: prečnik brizgaljke, debljina definisanog sloja, procentualna vrednost ispune, veličina uzorka koji se puni, brzina punjenja i temperatura proizvodnje. Cilj ovog rada je da se prikaže postupak realizacije kutije elektronike za malogabaritni transmiter pritiska na 3D štampaču. Time se projektantu daje mogućnost da ispravi postojeće greške, modifikuje proizvod prema zahtevima krajnjih korisnika i na kraju daje polazna osnova za realizaciju prototipa novog proizvoda.Additive manufacturing involves manufacturing of products with complex geometry in relatively small quantities, as well as the tools and molds manufacturing for mass production. With additive manufacturing, digital models are being realized and implementation is huge in various industrial sectors. Compared to traditional manufacturing, the main parameters in the choice of additive technology are: energy savings, waste reduction, reduced use of more tools and optimization of design. Additive manufacturing or 3D printing technology works on the principle of adding material in layers, i.e. the model is formed from layers of molten material that is immediately cooled and solidified. 3D printing allows to work with customers to solve design problems before embarking on a launch production. The starting material for the model is polyactic acid (PLA). It is an eco-friendly thermoplastic polyester, that breaks down naturally. The mechanical characteristics of the realized PLA model are significantly influenced by various technological variables, such as following: nozzle diameter, thickness of defined layer, percentage of fill, sample size to be filled, filling rate and production temperature. The aim of this paper is to present the process of realization of an electronics enclosure for a compact pressure transmitter on a 3D printer. This gives the designer the possibility to correct existing errors, modify the product according to the wishes of the end users and finally provides a starting point for the prototype of new product

The usage of 3D printing in the analysis of the product design: Case – Electronic enclosure of compact pressure transmitter

Aditivna proizvodnja uključuje izradu proizvoda složene geometrije u relativno malim količinama, kao i izradu alata i kalupa za masovnu proizvodnju. Aditivnom proizovnjom realizuju se modeli prema digitalnom prikazu, a primena je ogromna u različitim industrijskim sektorima. U poređenju sa tradicionalnom proizvodnjom, glavni parametri u odabiru aditivne tehnologije su: ušteda energije, smanjenje otpada, smanjenje upotrebe većeg broja alata, kao i optimizacija dizajna. Aditivna proizvodnja ili tehnologija 3D štampe rade na principu dodavanja materijala u slojevima, tj. model se formira od slojeva rastopljenog materijala koji se odmah hladi i očvršćava. 3D štampa omogućava čestu i jednostavnu modifikaciju modela na zahtev kupca, a pre ulaska modela u samu proizvodnju. Ovo čini komunikaciju na relaciji proizvođač-kupac dosta jednostavnom. Polazni materijal za izradu modela je polilaktična kiselina (PLA). To je ekološki termoplastični poliester koji se prirodno razgrađuje u prirodi. Na mehaničke karakteristike realizovanog modela od PLA značajno utiču različite tehnološke promenljive kao što su: prečnik brizgaljke, debljina definisanog sloja, procentualna vrednost ispune, veličina uzorka koji se puni, brzina punjenja i temperatura proizvodnje. Cilj ovog rada je da se prikaže postupak realizacije kutije elektronike za malogabaritni transmiter pritiska na 3D štampaču. Time se projektantu daje mogućnost da ispravi postojeće greške, modifikuje proizvod prema zahterima krajnjih korisnika i na kraju daje polazna osnova za realizaciju prototipa novog proizvoda.Additive manufacturing involves manufacturing of products with complex geometry in relatively small quantities, as well as the tools and molds manufacturing for mass production. With additive manufacturing, digital models are being realized and implementation is huge in various industrial sectors. Compared to traditional manufacturing, the main parameters in the choice of additive technology are: energy savings, waste reduction, reduced use of more tools and optimization of design. Additive manufacturing or 3D printing technology works on the principle of adding material in layers, i.e. the model is formed from layers of molten material that is immediately cooled and solidified. 3D printing allows to work with customers to solve design problems before embarking on a launch production. The starting material for the model is polyactic acid (PLA). It is an eco-friendly thermoplastic polyester, that breaks down naturally. The mechanical characteristics of the realized PLA model are significantly influenced by various technological variables, such as following: nozzle diameter, thickness of defined layer, percentage of fill, sample size to be filled, filling rate and production temperature. The aim of this paper is to present the process of realization of an electronics enclosure for a compact pressure transmitter on a 3D printer. This gives the designer the possibility to correct existing errors, modify the product according to the wishes of the end users and finally provides a starting point for the prototype of new product

Antimicrobial activity and cytotoxicity of silver-based nanoparticles in situ synthesized on cotton fabric using walnut leaf

U ovom radu je ispitana mogućnost in situ sinteze nanočestica na bazi srebra primenom ekstrakta lista oraha, na pamučnoj tkanini prethodno modifikovanoj limunskom kiselinom. Tokom sinteze su formirane sferne nanočestice prečnika oko 60 nm, koje su ravnomerno raspoređene po površini pamučnih vlakana. Prisustvo nanočestica na bazi srebra je obezbedilo odličnu antimikrobnu aktivnost prema bakterijama Staphylococcus aureus i Escherichia coli, kao i kvascu Candida albicans. Tekstilni nanokompozitni materijal nije citotoksičan prema ćelijama zdravih keratinocita kože (HaCaT linija) i zdravih fibroblasta (MRC-5 linija), što omogućava njegovu bezbednu primenu za medicinske potrebe.This study discusses the possibility to utilize walnut leaf extract for in situ synthesis of silver-based nanoparticles on cotton fabric previously modified with citric acid. Synthetized spherical nanoparticles with an average diameter of 60 nm were evenly distributed over the surface of cotton fibers. The presence of silver-based nanoparticles provided excellent antimicrobial activity against bacteria Staphylococcus aureus and Escherichia coli, and yeast Candida albicans. The textile nanocomposite did not show any cytotoxicity towards healthy skin keratinocytes cells (HaCaT line) and healthy fibroblast cells (MRC-5 line). Thus, it could be considered as a safe for potential medical applications

Urine-based testing for Chlamydia trachomatis among young adults in a population-based survey in Croatia: Feasibility and prevalence

<p>Abstract</p> <p>Background</p> <p>We assessed the feasibility of collecting urine samples for testing on genital <it>Chlamydia trachomatis </it>infection in a population-based survey, and prevalence of this infection among young people aged 18-25 in Croatia. In Croatia, as in the other countries of Eastern Europe, there is a lack of data on prevalence of <it>C trachomatis </it>in the general population, including young adults.</p> <p>Methods</p> <p>We sampled participants using a nationally representative, multi-stage stratified probability sample of young men and women. Detection of <it>C trachomatis </it>DNA in urine samples was performed by using a real-time PCR assay COBAS^®TaqMan^®CT Test, v2.0.</p> <p>Results</p> <p>Overall, 1005 young adults participated in the behavioural part of the survey, and 27.9% men and 37.5% women who were sexually experienced agreed to provide urine samples for testing on <it>C trachomatis</it>. Using multivariate analysis, women were significantly more likely to provide urine samples than men (aOR = 1.53, 95% CI 1.14-2.06) as were those who reported no condom use at last intercourse (aOR = 1.95, 95% CI 1.44-2.62). Prevalence of <it>C trachomatis </it>infection among those who were sexually experienced was 7.3% in men and 5.3% in women.</p> <p>Conclusions</p> <p>Population-based surveys that use probabilistic sampling are a feasible way to obtain population estimates of <it>C trachomatis </it>prevalence among young adults in Croatia, but it is challenging to obtain an adequate response rate. The prevalence of <it>C trachomatis </it>among young adults in Croatia found in this study was higher than that found in other European countries with similar survey response rates.</p

Analysis and interpretation of the model of a Faraday cage for electromagnetic compatibility testing

In order to improve the work of the Laboratory for Electromagnetic Compatibility Testing in the Technical Test Center (TTC), we investigated the influence of the Faraday cage on measurement results. The primary goal of this study is the simulation of the fields in the cage, especially around resonant frequencies, in order to be able to predict results of measurements of devices under test in the anechoic chamber or in any other environment. We developed simulation (computer) models of the cage step by step, by using the Wipl-D program and by comparing the numerical results with measurements as well as by resolving difficulties due to the complex structure and imperfections of the cage. The subject of this paper is to present these simulation models and the corresponding results of the computations and measurements. Construction of the cage The cage is made of steel plates with the dimensions 1.25 m x 2.5 m. The base of the cage is a square; the footprint interior dimensions are 3.76 m x 3.76 m, and the height is 2.5 m. The cage ceiling is lowered by plasticized aluminum strips. The strips are loosely attached to the carriers which are screwed to the ceiling. The cage has four ventilation openings (two on the ceiling and two on one wall), made of honeycomb waveguide holes. In one corner of the cage, there is a single door with springs made of beryllium bronze. For frequencies of a few tens of MHz, the skin effect is fully developed in the cage walls. By measuring the input impedance of the wire line parallel to a wall of the cage, we calculated the surface losses of the cage plates. In addition, we used a magnetic probe to detect shield discontinuities. We generated a strong current at a frequency of 106 kHz outside the cage and measured the magnetic field inside the cage at the places of cage shield discontinuities. In this paper, we showed the influence of these places on the measurement results, especially on the qualitative and quantitative changes of the cage resonant frequencies. Model of the cage On the basis of the testing, the initial simulation model of the cage in the Wipl-D program consists of plates with losses, including losses at plate junctions, wall ventilation openings, aluminum profiles, profile carriers, and screws. The analysis showed that this model is not satisfactory. To obtain a more accurate model of the cage, we need the additional and more precise model of the lowered ceiling. That would complicate the model and require a lot of additional testing. For obtaining a simpler, but more reliable simulation model, we dismounted the aluminum profiles from the carriers. Thereafter, the agreement between the simulation and the experimental results was better than for the initial model, but still is not good enough, due to the uncertainties caused by the strips carriers and the screws. Final model of the cage To avoid the uncertainty due to the strips carriers, we removed the carriers and the screws from the cage. A very good matching of the simulation and the experimental results was achieved. We showed that the relative difference of the resonant frequencies between simulation and measurement is less than 1 %. However, the relative difference of resonant frequency between simulation or measurement and theoretical results is also less than 1 %, except for TE101 and TE011 modes, for which the relative difference is under 5 %. We explained the exception by the influence of the places of the cage shield discontinuities on the measurement results. Conclusion The results of the simulations and the measurements for the final model show good agreement, both qualitatively and quantitatively. We showed that the resonant frequencies in the simulations and the measurement results have same positions and depths. Also, the relative differences of the resonant frequencies are less than 1 %. As future work, we will provide a technique for the identification of equivalent sources that represent the device under test. This would enable a characterization of the tested device in an arbitrary electromagnetic environment and allow a comparison of results obtained in different laboratories. </p

Simulacija rada visoke peći prilikom supstitucije koksa i sprašenog uglja granulisanom otpadnom plastikom

The possibility of using the waste plastic as reducing agent in blast furnace for obtaining pig iron is in focus for the past couple year. The simulation of blast furnace process in BFC software has been performed in order to analyze the coke and coals saving, CO2 emission and determining the economic benefits. Three different batches were made for comparative analysis, depending on the batch composition and input of batch components into the blast furnace: case 1 (C1), case 2 (C2) and case 3 (C3). The base case, C1 contains sinter (bulk material) which is needed for obtaining 1 tone of pig iron, quartz which provides slag alkalinity and coke as reducing and energy agent. C2 has the same components as C1, but contains pulverized coal instead one part of coke and C3 contains granulated waste plastic instead coke in an approximately the same amount as pulverized coal. The substitution of coke with pulverized coal and waste plastic is 18.6 % and 25.2 %, respectively. The economic, productivity and ecologic aspects have been analyzed. The consumption of each tone of waste plastic in blast furnace saves 360 $, which is 18 times more than its price, bearing in mind that the market price of coke is 380$/t % and waste plastic 20 $/t. Regarding the specific productivity, it decreases from 2.13 for C1 to 1.87 for C3. From an environmental aspect there are two main benefits: reduction of CO2 emission and impossibility of dioxin formation. The CO2 emission was 20.18, 19.46 and 17.21 for C1, C2 and C3, respectively.Mogućnost upotrebe otpadne plastike kao reducenta u visokoj peći je u fokusu interesovanja poslednjih godina. U cilju analize uštede koksa i uglja, smanjenja emisije CO2 i utvrđivanja ekonomskih benefita urađena je simulacija visokopećnog procesa u BFC programskom paketu. Radi uporedne analize simulirana su tri slučaja u zavisnosti od sastava šarže i načina unošenja komponenti šarže u visoku peć: sučaj 1 (S1), slučaj 2 (S2) i slučaj 3 (S3). Šarža u baznom slučaju, S1, se sastoji od sintera, tj. zasipa koji je potreban da se dobije 1 t gvožđa, topitelja koji obezbeđuje bazicitet troske i koksa kao reducenta i energenta. Šarža u slučaju S2, pored komponenata koje sadrži šarža u slučaju S1, sadrži sprašeni ugalj umesto jednog dela koksa, a šarža u slučaju S3 umesto koksa sadrži granulisanu otpadnu plastiku u približno istoj količini kao sprašeni ugalj. Supstitucija koksa sprašenim ugljem i otpadnom plastikom je 18,6$, što je 18 puta više od njene cene imajući u vidu da je tržišna cena koksa 380 $/t, a otpadne plastike 20$/t. Što se tiče specifične proizvodnosti, ista opada od 2,13 za S1 do 1,87 za S3. Sa ekološkog aspekta postoje dva glavna benefita: smanjenje emisije CO2 i nemogućnost formiranja dioksina. Emisija CO2 je bila 20,18; 19,46 i 17,21 % za S1, S2 i S3, respektivno

Sustainable non-woven sorbents based on jute post-industrial waste for cleaning of oil spills

Intensified oil exploitation accompanied with frequent oil spills having a detrimental impact on ecosystems are seeking efficient, environmentally and economically feasible solutions. In an attempt to develop an efficient, reusable, biodegradable and cheap sorbent for oil clean-up non-woven sorbents based on recycled jute post-industrial textile waste were fabricated. The influence of area density of non-woven sorbents and hydrophobicity of fibers on overall oil sorption performance was the focus of this research. All sorbents showed a good reusability after five sorption cycles and buoyancy in water even after 24 h independently of sorbent structure. The area density of sorbents and viscosity of studied oils (crude oil, diesel oil and two types of motor oils) highly affected the oil sorption capacity and oil retention. The sorbent with the lowest area density exhibited the best oil sorption performance. The esterification of jute with stearic fatty acid contributed to decrease in water uptake of sorbents but also to negligible change of oil sorption behavior indicating that the structure of the sorbent in this case plays a crucial role

Structurally and surface-modified alumina particles as a reinforcement in polyester-based composites with an improved toughness

Commercial gamma - Al2O3 particles, Al2O3 n, and synthesized Al2O3 doped with iron oxide (Al2O3 Fe) were used as reinforcements to enhance the toughness of an unsaturated polyester resin (UPR). Alumina modification with vinyl, Al2O3 (n, Fe)-VT, and methacryloyl, Al2O3 (n, Fe)-ME functionalities contributed to the increase in the extent of covalent binding at the UPR/filler interface. Tensile tests showed a slight improvement in the toughness of UPR/Al2O3 Fe composite and a significant improvement for the UPR/Al2O3 Fe-VT composite at a 1.0 wt.% particle loading. An enhancement in the micro Vickers hardness for UPR/Al2O3 Fe-VT and improved DMA properties were also evidenced