Modeling of the Protection Current/Potential Distribution

U radu je prezentirano korištenje numeričkih metoda za proračun raspodjele zaštitnih struja/potencijala u sustavima katodne zaštite s galvanskim anodama. Analizirana je kombinirana metoda BEM/FEM, tj. kombinacija metode rubnih i konačnih elemenata. Sustav katodne zaštite je vrlo učinkovit sustav za zaštitu podzemnih metalnih objekata od korozije. Optimalno i tehnički korektno definiranje raspodjele zaštitne struje predstavlja najvažniju fazu kod projektiranja sustava katodne zaštite. Određivanje raspodjele zaštitnih struja/potencijala u sustavima katodne zaštite temelji se na rješavanju Laplaceove jednadžbe uz korištenje adekvatnih, prethodno definiranih rubnih uvjeta. Ovi uvjeti su definirani preko analitičkih izraza za funkcionalne odnose između gustoća zaštitnih struja i potencijala na elektrodnim površinama, odnosno na granicama elektroda/elektrolit. Na istom objektu za kojeg su urađeni numerički proračuni izvršena su i mjerenja raspodjele zaštitnih potencijala tijekom vremena eksploatacije. Eksperimentalni podaci, koji su dobiveni tijekom puštanja sustava u funkciju te namjenski pravljenih periodičnih mjerenja tijekom održavanja sustava uspoređeni su s numerički dobivenim vrijednostima.The use of numerical methods for calculation of protection current/potential distribution in cathodic protection systems with galvanic anodes is presented in this paper. The coupled BEM/FEM method has been analysed, i.e. a combination of the Boundary Element Method (BEM) and the Finite Element Method (FEM). The cathodic protection system is a very efficient system for the protection of underground metal structures from corrosion. The most important phase of the projecting of the cathodic protection system is the optimally and technically correct defining of protection current distribution.. The calculation of protection current/potential distribution in cathodic protection systems is based on solving Laplace’s equation using adequate, previously defined, boundary conditions. These conditions are defined by using analytical expressions for the functional relationship between protection current and potential on electrode surfaces, or the electrode/electrolyte boundary. On the same structure for which the numerical calculations were made, measurements of protection potential distribution during the time of exploitation have been taken. Experimental data acquired during the start of system operations, together with intentional periodical measurements during system maintenance, are compared with data acquired by numerical calculations

Environmentally Friendly Packaging Materials Based on Thermoplastic Starch

Low-density polyethylene (LDPE) is extensively used as packaging material, and as such has a short service life, but long environmental persistence. The alternative to reducing the impact of LDPE as packaging material on the environment is to blend it with carbohydrate-based polymers, like starch. Therefore, the focus of this investigation was to prepare bio-based blends of LDPE and thermoplastic starch (TPS) containing different amounts of TPS using a Brabender kneading chamber. Due to incompatibility of LDPE/TPS blends, a styrene–ethylene/butylene–styrene block copolymer, grafted with maleic anhydride (SEBS-g-MA) containing 2 mol % anhydride groups, was added as a compatibilizer. The effect of the biodegradable, hydrophilic TPS, its content, and the incorporation of the compatibilizer on the properties of LDPE/TPS blends were analysed. The characterization was performed by means of thermogravimetric analysis (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and water absorption (WA). Based on the results of the morphological structure, a good dispersion of the TPS phase in LDPE matrix was obtained with the incorporation of compatibilizer, which resulted in better thermal and barrier properties of these materials

Modeling of the Protection Current/Potential Distribution

U radu je prezentirano korištenje numeričkih metoda za proračun raspodjele zaštitnih struja/potencijala u sustavima katodne zaštite s galvanskim anodama. Analizirana je kombinirana metoda BEM/FEM, tj. kombinacija metode rubnih i konačnih elemenata. Sustav katodne zaštite je vrlo učinkovit sustav za zaštitu podzemnih metalnih objekata od korozije. Optimalno i tehnički korektno definiranje raspodjele zaštitne struje predstavlja najvažniju fazu kod projektiranja sustava katodne zaštite. Određivanje raspodjele zaštitnih struja/potencijala u sustavima katodne zaštite temelji se na rješavanju Laplaceove jednadžbe uz korištenje adekvatnih, prethodno definiranih rubnih uvjeta. Ovi uvjeti su definirani preko analitičkih izraza za funkcionalne odnose između gustoća zaštitnih struja i potencijala na elektrodnim površinama, odnosno na granicama elektroda/elektrolit. Na istom objektu za kojeg su urađeni numerički proračuni izvršena su i mjerenja raspodjele zaštitnih potencijala tijekom vremena eksploatacije. Eksperimentalni podaci, koji su dobiveni tijekom puštanja sustava u funkciju te namjenski pravljenih periodičnih mjerenja tijekom održavanja sustava uspoređeni su s numerički dobivenim vrijednostima.The use of numerical methods for calculation of protection current/potential distribution in cathodic protection systems with galvanic anodes is presented in this paper. The coupled BEM/FEM method has been analysed, i.e. a combination of the Boundary Element Method (BEM) and the Finite Element Method (FEM). The cathodic protection system is a very efficient system for the protection of underground metal structures from corrosion. The most important phase of the projecting of the cathodic protection system is the optimally and technically correct defining of protection current distribution.. The calculation of protection current/potential distribution in cathodic protection systems is based on solving Laplace’s equation using adequate, previously defined, boundary conditions. These conditions are defined by using analytical expressions for the functional relationship between protection current and potential on electrode surfaces, or the electrode/electrolyte boundary. On the same structure for which the numerical calculations were made, measurements of protection potential distribution during the time of exploitation have been taken. Experimental data acquired during the start of system operations, together with intentional periodical measurements during system maintenance, are compared with data acquired by numerical calculations

Influence of Lithium on Nanosized Films of Fe 2

We have investigated nanosized thin films of α-Fe2O3 (hematite) and α-Fe2O3 with addition of Li, by the impedance spectroscopy (IS), the Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Combining all of these methods, and earlier obtained thermally stimulated currents (TSC) on the same samples, the dependence of structural and electrical properties upon percentage of Li added into the matrix of these metal-oxide films was found. The comparison of IS, Raman, SEM, XRD, and TSC results reveals the increase of the size of nanoparticles upon inducing 1% of Li in Fe2O3 matrix followed by the decrease of the size of nanoparticles in the case of samples with 10% Li, as well as the decrease (increase) of conductivity, respectively. These changes are explained by the structural and morphological changes caused by the impact of Li+ ions in the charge transfers. This material is suitable for application in the galvanic cell of second generation that could be used as solar-cells backup

Differences between morphological characteristics and motoric capabilities of physically active and inactive female students

Background: This research was done as continuation of research made previously on male population. The goal of this research is to determine „differences between morphological characteristics and motoric capabilities of physically active and inactive female students “. Methods: Sample of physically inactive female students was made of 54 examinees and sample for active students was made of 52 girls. Average age was 12. All girls were primary school students. Physically inactive students regularly attended PE lessons and active students were involved in training process of basketball, volleyball, football and handball teams. Additional practice was done two times a week for 90 minutes. Morphological space is set by 15 variables and motoric space is set with 24 variables. Results: Statistical difference was determined by T-test on level (p<0.05). Significance given by T-test was checked by calculating Eta coefficient. Such data has differences in Chest Width (.00/.00 and η2=0,33), Weight (.00/.00 and η2=0,34), Stomach Skin Curves (.00/.00 and η2=0,37) and Back Skin Curves (.05/.05 and η2=0,16). Motoric space has differences in: Slalom with Three Medicine Balls (.00/.00 and η2=0.01), Throwing medicine ball from the chest (.00/.00 and η2=0,10), Long Jump (.00/.00 and η2=0,17), Push-ups (.02/.02 and η2=0.05), Sit-and-Reach (.04/.04 and η2=0.00) and 20m low start run (.00/.00 and. η2=0,14). Conclusions: After analysis it can be stated the aim of the research was completed and differences of anthropological status of physically active and inactive female students were determined. Students of age 12 can be recommended additional training activity to positively transform anthropological spaces with no transformation. Research with same or similar variables should be done on different age categories when compared to this one or to analyze quality of influence that specific sports have on transformation in this age category