Influence of reflectance from flat aluminum concentrators on energy efficiency of PV/Thermal collector

In this paper the results of the influence of reflectance from flat plate solar radiation concentrators made of Al sheet and Al foil on energy efficiency of PV/Thermal collector are presented. The total reflectance from concentrators made of Al sheet and Al foil is almost the same, but specular reflectance which is bigger in concentrators made of Al foil results in increase of solar radiation intensity concentration factor. With the increase of solar radiation intensity concentration factor, total daily thermal and electrical energy generated by PV/Thermal collector with concentrators increase. In this work also optimal position of solar radiation concentrators made of Al sheet and Al foil and appropriate thermal and electrical efficiency of PV/Thermal collector have been determined. Total energy generated by PV/Thermal collector with concentrators made of Al foil in optimal position is higher than total energy generated by PV/Thermal collector with concentrators made of Al sheet.     

Polyaniline as cathodic material for electrochemical energy sources: The role of morphology

Polyaniline layers of different morphologies ranging from open and “sponge-like” structures to compact and “pebble-like” surfaces were synthesized from perchlorate solutions and employed as cathode in the galvanic cell with Zn anode and NH₄Cl/ZnCl₂ electrolyte. Cathodic properties of synthesized layers were investigated by the constant current charging/discharging method in 500 cycles. Specific charge capacities and specific energies obtained form the current-time curves strongly depend on the morphology of investigated layers and discharge conditions. The results unambiguously show that charging/discharging reaction of polyaniline layers is limited to relatively thin layer at polymer/solution boundary. Specific charge capacities are inversely related to both the polymer thickness and the discharge current density. In the limit of zero current densities the specific charge capacity as high as 245 A h kg⁻¹ could be achieved for porous structures of polyaniline layers. Specific capacitance higher than 400 F g⁻¹ obtained at 2 mA cm⁻² current density makes polyaniline a promising material for the application in electrochemical supercapacitors. The electrochemical behaviour of the layers was investigated by cyclic voltammetry and electrochemical impedance spectroscopy before and after 500 cycles of charging/discharging experiments. Both, cyclic voltammetry and electrochemical impedance spectroscopy showed that some polyaniline layers develop an increased charged transfer resistance at the carbon support/polymer interface during charging/discharging process. The increased charge transfer resistance does not affect the overall specific charge of the layers. The low-frequency capacities in impedance spectra are attributed to charging/discharging of polymer/electrolyte interface and seem to be related to the specific charge capacities obtained by extrapolation to zero current density discharge reaction.     

Analysis of economic characteristics of a tariff system for thermal energy activities

Generally speaking, the creation of tariff systems for energy activities carried out as regulated or public service obligation is becoming professionally challenging. The Croatian Energy Regulatory Agency (CERA) created the methodology of the tariff system for thermal energy activities and passed this tariff system (without tariff element amounts) in May 2006. The background of the tariff system for thermal energy activities (heat generation, heat distribution and heat supply) including a legislative framework relevant for passing the tariff system, terminology, matrix of the tariff models, tariff elements and amounts of tariff entries are analyzed in this paper. Special attention is paid to the economic characteristics of the tariff system, such as the capital asset pricing model (CAPM), which is chosen among several models of the weighted average of cost of capital (WACC). Using the WACC, the regulatory authorities ensure returns to be equal to the opportunity cost of capital. Furthermore, main formulae and procedures for submitting the proposal for changing the amounts of tariff elements are analyzed as well.     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

Lead and cadmium in red deer and wild boar from different hunting grounds in Croatia

The concentration and relations of Cd and Pb as environmental risk factors were studied by atomic absorption spectrophotometry in the liver, kidney and muscle of free ranging wild boar (n = 94) and red deer (n = 45) from hunting grounds in four counties of north-east Croatia. In all four counties, the levels of Cd found in the kidney of red deer ranged from 2.28 to 5.91 mg/kg, and in wild boar from 3.47 to 21.10 mg/kg. The mean renal concentration of Cd was significantly higher in wild boar than in red deer from all four study areas. The mean hepatic (0.11 to 0.49 mg/kg, respectively) and muscle (0.01 to 0.04 mg/kg, respectively) Cd concentrations were similar in both species. The mean renal Cd concentration in wild boar and red deer exceeded 1 mg/kg in all four counties, ranging from 67.0% to 91.4% and from 45.5% to 69.2%, respectively. Also, the hepatic Cd/renal Cd ratio was lower than 1 in all animals. In all four counties, renal Pb concentration ranged from 0.058 to 3.77 mg/kg in red deer and from 0.056 to 11.60 mg/kg in wild boar. Hepatic Pb concentration was similar in both species (0.061 to 0.202 mg/kg in wild boar and 0.077 to 0.108 mg/kg in red deer). Because of the high Cd level in the organs of wild boar and red deer, further research is needed to identify the source of contamination in order to preserve the health of animals and humans.     

Characterization of traditional Istrian dry-cured ham by means of physical and chemical analyses and volatile compounds

The aroma-active compounds of Istrian dry-cured ham were investigated by using headspace-solid phase microextraction and gas chromatography-mass spectrometry (GC-MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics: moisture, protein, fat, ash and NaCl content, a(w) value; colour: L*, a*, b* and oxidation of fat: TBARS test. About 50 volatile compounds were identified and quantified which belonged to several classes of chemical: 5 alcohols, 8 aldehydes, 7 alkanes, 1 ketone, 2 esters, 9 monoterpenes and 15 sesquiterpenes. Except volatile compounds derived from lipolysis and proteolysis the most abundant constituents were terpenes (62.97; 41.43%) that originate from spices added in the salting phase of the production process.     

Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham

The aim of this work was to determine the characteristics of Istrian dry-cured ham by instrumental methods and sensory analysis. The aroma-active compounds of Istrian dry-cured ham from 2010 and 2012 were investigated by using headspace-solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics. 92 volatile aroma compounds of Istrian dry-cured ham were found. Volatile compounds belonged to several chemical groups: aldehydes (51.4; 51.3%), terpenes (16.5; 16.4%), alcohols (15.5; 13.2%), ketones (8.6; 7.4%), alkanes (3.8; 5.7%), esters (1.3; 1.6%), aromatic hydrocarbons (0.8; 3.9%) and acids (0.6; 0.9%). Principal component analysis (PCA) showed that fat content, tenderness and melting texture were positively correlated. Terpenes were strongly correlated with flavour of added spices. Sweet taste and the presence of esters were positively correlated as well as negative odour, raw meat flavour and water content.     

Oxygen plasma pretreatment improves dyeing and antimicrobial properties of wool fabric dyed with natural extract from pomegranate peel

This paper presents the application of conventional potassium aluminium sulphate wool mordanting and a biochemical method with silver nitrate (as antimicrobial agent and mordant)_, alone and in combination with oxygen plasma, as part of comprehensive research into pretreatment processes for wool dyeing with natural extract from pomegranate peel (Punica granatum L.). Pretreatment with oxygen plasma significantly improved the hydrophilicity and tensile strength of all tested samples and showed that oxygen plasma can improve K/S, washing fastness, and even replace certain mordants in wool dyeing with natural pomegranate dye. All dyed samples exhibited good antibacterial activity against Staphylococcus aureus, which can be contributed to the phenol content in pomegranate dye. Only after 28 days of intensive ageing in natural weathering conditions did K/S and antibacterial activity against Klebsiella pneumoniae slightly decrease in dyed samples pretreated with oxygen plasma.     

Salt and moisture content determination of fish by bioelectrical impedance and a needle-type multi-electrode array

The aim of this study was to test the applicability of bioelectrical measurements and a needle-type multi-electrode array in evaluating salt and moisture content of structurally heterogeneous food samples, such as fish. Impedance measurements were performed at different frequencies in order to find the most appropriate range, where impedance module and/or phase angle are the most sensitive to salt and moisture content. The salt, moisture, and water phase salt (WPS) of the salted rainbow trout samples were successfully evaluated by the impedance module measured at 50 kHz (AdR2 > 0.85). Due to rapid and non-destructive analysis coupled with low cost device design, this method for determination of salt and/or moisture has potential as the quality control technique for the fish industry.     

Triacylglycerols composition of oil in OS soybean cultivars

Oil content in grain and triacylglycerol composition of several Croatian soybean cultivars (Glycine max (L) Merrill) was investigated. Trials were conducted at two localities during three years and involved seven soybean cultivars. All investigated cultivars were created in soybean breeding program at the Agricultural Institute Osijek in Croatia. Oil content in grain was determined by NMR method. Triacylglycerols were analyzed by reversed phase high performance liquid chromatography with refractive index detector and identified by comparing their retention time to standards.Oil content was similar in soybean cultivars within year and localities but varied significantly among years. Chromatograms of every injected sample showed 15 individual triacylglycerol peaks, and the main components are trilinolein, dilinoleoolein, and dilinoleopalmitin. A small difference of triacylglycerol composition was noticed among soybean cultivars whereas larger one was noticed among the investigated years. The obtained results will be able to use in further breeding work for soybean cultivars grain quality improvement.