Pearl culture – cultivation of pearl oysters (Bivalvia: Pteriidae)

Perlikultura je proces uzgoja bisernica namijenjenih za proizvodnju bisera. Sastoji se od skupljanja bisernica u njihovom prirodnom okolišu, premještanja u mrijestilišta, nasađivanja mladih bisernica na podlogu i proizvodnje bisera. U ovom radu obrađene su vrste Pinctada maxima, P. margaritifera i P. fucata,koje se najviše komercijalno iskorištavaju, te neke od metoda za njihov uzgoj. Metode se biraju s obzirom na vrstu bisernice i okolišne čimbenike. Iako bisernice iz uzgoja na kraju budu ubijene, a neki njihovi dijelovi prodani, razvoj perlikulture je smanjio njihovo izlovljavanje iz prirodnih staništa, a time ih je i sačuvao od istrebljenja. Perlikultura također sadrži potencijal za ekonomski razvoj malih obalnih mjesta.Pearl culture is a process of cultivating pearl oysters to produce pearls. It consists of collecting animals from their natural habitat, their relocation into hatcheries, the ongrowing of spat and pearl production. This paper presents the commercially most valuable pearl oyster species (Pinctada maxima, P. margaritifera and P. fucata) and the methods that are being used to cultivate them. The methods are being chosen according to specific species and environmental factors. Although bred pearl oysters eventually end up dead and their parts get sold, the development of pearl culture has significantly reduced fishing from their natural habitat and saved pearl oysters from extinction. Pearl culture also presents a significant potential for economic development of small coastal villages

Prvi nalaz vrste Nubensia nubens (Edwards, 1929) (Diptera: Chironomidae) u Hrvatskoj

The species Nubensia nubens (Edwards, 1929) from the dipteran family Chironomidae has been recorded for the first time in Croatian chironomid fauna. It was found in the littoral of the oligotrophic Lake Vrana on the island of Cres. The species is known from Italy, Albania and the Republic of Northern Macedonia as well as western Europe, the Czech Republic and the Pyrenees. Lake Vrana is currently the only known habitat of this species in Croatia.Vrsta Nubensia nubens (Edwards, 1929) koja pripada porodici Chironomidae zabilježena je po prvi puta u fauni Hrvatske. Pronađena je u litoralu Vranskog jezera na otoku Cresu. Ova vrsta je poznata u fauni Italije, Albanije te Republike Sjeverne Makedonije, kao i s područja zapadne Europe, Češke i Pirineja. Vransko jezero na otoku Cresu zasad je jedino poznato stanište ove vrste u Hrvatskoj

Effect of food attractants on insecticidal efficacy of entomopathogenic nematodes (Steinernema feltiae) against Tribolium castaneum larvae

Štetni kukci u uskladištenim proizvodima su postali veliki problem zbog rezistentnosti na pesticide. Pojavljuje se sve veća potreba za biološkim preparatima. Cilj istraživanja je utvrditi utjecaj hranidbenih atraktanata kao mamaca s entomopatogenim nematodama (Steinernema feltiae) na mortalitet ličinki kestenjastog brašnara (Tribolium castaneum). Pokus je postavljen u Petrijevim zdjelicama, s lomom zrna pšenice u četiri tretmana i tri ponavljanja, te je proveden u mraku na dvije temperature. Nakon desetog dana izloženosti ličinki kestenjastog brašnara nematodama S. feltiae u tretmanu 700 nematoda po kukcu, utvrđen je najveći mortalitet, odnosno utvrđeno je više od 80% uginulih ličinki kestenjastog brašnara. No, nisu utvrđene statistički značajne razlike između tretmana. Također, nije utvrđen statistički značajan utjecaj temperature u ovom pokusu. Hranidbeni atraktant nije pospješio infektivnost odnosno patogenost S. feltiae. Ličinke kestenjastog brašnara dobar su domaćin za S. feltiae, no potrebna su dodatna istraživanja koristeći druge metode ispitivanja patogenosti s obzirom da nisu utvrđene statistički značajne razlike u odnosu na kontrolu.Stored products insects pests have become a major problem in agriculture due to resistance to pesticides. There is an increasing need for biological control solutions. The aim of the study is to determine effect of food attractants on insecticidal efficacy of entomopathogenic nematodes (Steinernema feltiae) against Tribolium castaneum larvae. The experiment was set up in Petri dishes with wheat grain as food attractant in four treatments and three repetitions, and it was conducted in dark at two temperatures. The highest mortality was observed in treatment with 700 nematodes per insect larvae, where more than 80% of insect larvae were found dead. There were no statistical differences between the treatments, and no significant effect of temperature regime was observed. Food attractant did not enhance nematodes pathogenicity. The larvae of red flour beetle are susceptible and good host for S. feltiae, however different methods of testing their pathogenicity against their pest are needed to ensure significant results

Control loop optimisation in crude distillation unit

Ovaj rad obrađuje optimiranje regulacijskih krugova rafinerijskog procesa atmosferske destilacije nafte. U teorijskom dijelu rada opisan je proces i metode vođenja atmosferske destilacije, a zatim su prikazane metode optimiranja vođenja i razvoja empirijskih modela procesa. Eksperimentalni dio obuhvatio je analizu i optimiranje regulacije razine stripera teškog benzina i stabilizatora primarnog benzina. Na temelju podataka s postrojenja simulirano je dinamičko vladanje regulacijskih krugova, a optimirani parametri regulatora primijenjeni su na postrojenju. Djelovanje regulacijskih krugova prije i poslije optimiranja uspoređeno je kriterijima kvalitete regulacije i statističkim pokazateljima.This paper describes optimisation of control loops in crude distillation unit in oil refineries. Theoretical part contains description of processes and process control in crude distillation unit, methods for optimization of process control and development of empirical models. Experimental part includes analysis and optimisation of controller parameters for level control in processes of naphtha stripping and naphtha stabilization. Data from crude distillation unit was used to simulate dynamics of control loops. Optimized controller parameters were applied on crude distillation unit. Operation of control loops before and after optimization was compared using control quality criteria and statistical indicators

Efficiency of a new internal combustion engine concept with variable piston motion

This paper presents simulation of working process in a new IC engine concept. The main feature of this new IC engine concept is the realization of variable movement of the piston. With this unconventional piston movement it is easy to provide variable compression ratio, variable displacement and combustion during constant volume. These advantages over standard piston mechanism are achieved through synthesis of the two pairs of non-circular gears. Presented mechanism is designed to obtain a specific motion law which provides better fuel consumption of IC engines. For this paper Ricardo/WAVE software was used, which provides a fully integrated treatment of time-dependent fluid dynamics and thermodynamics by means of onedimensional formulation. The results obtained herein include the efficiency characteristic of this new heat engine concept. The results show that combustion during constant volume, variable compression ratio and variable displacement have significant impact on improvement of fuel consumption

Simple analytical models for the calculation of the electric field radiated by the base station antenna

This paper outlines four different models for the assessment of the electric field radiated by the base station antenna system, thus featuring the Free Space Model (FS), Perfect Ground Model (PG), Fresnel Reflection Coefficient Model (RC) and Modified Image Theory Model (MIT). The results obtained with these approaches are compared to the results computed via Numerical Electromagnetics Code (NEC). Several variables have been varied to examine the accuracy of each calculation model. The calculations have been undertaken for the far field only. As many European countries perform the field assessment using the FS model, the final goal of this work is to come up with the most convenient model for the field calculation

A comparison of the MIKE 3 and PCFLOW3D models for hydrodynamic simulations in the Gulf of Trieste

A comparison between the hydrodynamic simulations of the models MIKE 3 and\ud PCFLOW3D in the Gulf of Trieste was performed.\ud The model MIKE 3 was developed at the Danish Hydraulic Institute (DHI). It is used to\ud simulate three-dimensional free-surface flow. At the Chair of Fluid Mechanics a similar\ud model PCFLOW3D is being developed and practically used since 1985. This model is used to\ud study processes in larger water bodies, such as lakes and seas, where the horizontal velocities\ud are larger than vertical for an order of magnitude. The basic characteristics of both models are\ud presented in this work.\ud The input data and a comparison of the results of some simulations performed in the Gulf of\ud Trieste with both models is further shown. Geometry and bathymetry data, temperature and\ud salinity conditions in the Gulf of Trieste and at the Soĉa river mouth, wind velocity and\ud direction as well as discharge and velocity of the River Soĉa were required for the\ud simulations. Realistic seasonal conditions were simulated using different turbulence models.\ud In the vicinity of the Soĉa river mouth a comparison of the results was performed also for a\ud refined numerical grid. The agreement of results was better in winter conditions (bora wind),\ud while simulations of tidal forcing and in summer conditions showed worse agreement of the\ud results.\ud The results of both models are comparable, despite relatively high discrepancies in some parts\ud of the modelling domain. Minor differences in numerical schemes and turbulence models\ud offered by both models and different input of boundary conditions, particularly at the open\ud boundary and in the inflow cell, were found to be the main reasons of discrepancies

Ideological-Cultural Matrix Intertwined in Space

Kroz teorijski alat raznih teoretičara prilazi se subjektovoj pozicioniranosti unutar spacijalnih praksi i konstruiranih prostora posredstvom tehnologija moći. Slojevitim slaganjem teorije kroz patchwork naglašava se analiza fragmentiranih pozicija pojedinca. Služeći se Foucaultovim metateorijskim čitanjem kroz rad pokušava se propitati ideološke niti koje ispresijecaju življeni realitet individue i na koji način to posljedično djeluje. Naglašavajući teoretska kretanja kroz binarno opozicioniranje paradigmi, pokušava se simptomatski iščitati njihovo značenje kao analognih procesa i transformacijska retorika. Razlažući početnu poziciju promatrača pokušava se odgovoriti na pitanje iz kojeg kuta pomatrati konstrukcije kojima je proţet svakodnevni realitet, te temelje na kojima počiva relacija između subjektovog stvarnog i imaginarnog u ispresijecanim prostorima življenog realiteta. Na koji način se demarkiraju pozicije unutar simboličkog, te gdje individua nalazi svoj prostor za djelovanje

An Improved Algorithm for Indirect Time domain Analysis of Thin Wire Structures

The algorithm for an indirect time domain (TD) analysis using arbitrary frequency domain method is presented. In previous work, an optimized version of the indirect timedomain method based on adaptive sampling iterative algorithm used in combination with inverse Fast Fourier Transform (FFT) was presented. In this paper, the algorithm is further improved by circumventing the use of inverse FFT altogether, and using the simple formula based on the analytical inverse Fourier transform. The proposed approach is simpler and more convenient for use with the underlying iterative optimization method, as only a part of the frequency domain (FD) signal has to be transformed to the time domain during each iteration procedure, the frequency domain discretisation does not have to be uniform, and the time domain discretisation does not have to be performed. These advantages can also lead to the reduced computational time cost of the frequency to time domain transformation when compared with the standard inverse FFT

Pastoral care in health and Catholic associations. Croatian Society of Nurses and Medical Technicians (HKDMST)

U nekoliko rečenica izneseni su podatci o nastanku i djelovanju Hrvatskoga katoličkog društva medicinskih sestara i tehničara (HKDMST) te o značajkama djelovanja društva, kao i samih katoličkih medicinskih sestara u bolnicama i nužnosti njihove suradnje s katoličkim liječnicima i posebno s duhovnicima, bolničkim kapelanima.The author briefly presented information on the development and activities of the Croatian Catholic Society of Nurses and Medical Technicians (HKDMST) and specifics of its activities, as well as the activities of Catholic nurses in hospitals and necessity of their cooperation with the Catholic doctors and particularly with clergymen, hospital chaplains