25 research outputs found
"Six Sigma" strategija
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Adaptive Neural Network Controller for Thermogenerator Angular Velocity Stabilization System
The paper presents an analytical and simulation approach for the selection of activation functions for the class of neural network controllers for shipās thermogenerator angular velocity stabilization system. Such systems can be found in many ships. A Lyapunov-like stability analysis is performed in order to obtain a weight update law. A number of simulations were performed to find the best activation function using integral error criteria and statistical T-tests
Production of fruit and vine planting material in 2017 in Croatia
Proizvodnju voÄnog i loznog poljoprivrednog sadnog materijala u 2017. godini za struÄni nadzor Hrvatskom centru za poljoprivredu, hranu i selo, Zavodu za sjemenarstvo i rasadaniÄarstvo prijavilo je 60 rasadnika voÄnih sadnica i 15 rasadnika loznih cijepova. Ukupno je prijavljeno 4.394.442 voÄnih sadnica i 3.057.226 loznih cijepova, Å”to predstavlja blagi porast koliÄine proizvodnje voÄnog i loznog sadnog materijala. Ukupno su u proizvodnji 31 voÄna vrsta i 69 sorti vinove loze. U prijavljenoj strukturi proizvodnje voÄnih sadnica najviÅ”e su zastupljene jabuke sa 36,01 % i lijeska sa 20,11 %, a zatim masline (6,42 %), kruÅ”ke (5,76 %), viÅ”nje (4,68 %), treÅ”nje (3,82 %), Å”ljive (3,65 %), itd. Od ukupne prijavljene koliÄine voÄnih sadnica 15 % su sadnice certificirane kategorije, dok je od ukupne prijavljene koliÄine loznih cijepova certificiranih 54 %.In the 2017 60 fruit and 15 grape vine nurseries have applied for official inspection of nursery production to Croatian Centre for Agriculture, Food and Rural Affairs, Institute for Seeds and Seedlings. 4.394.442 of fruit plants (33 species), and 3.057.226 of grape vine plants (69 varieties) have entered the sistem of official inspection which represents a minor increasing trend in fruit and vine planting material production. The largest part in production of fruit planting material are apples (36.01 % of total fruit species), followed by hazelnuts (20.11 %), olives (6.42 %), pears (5.76 %), cherries (4.68 %), sweet cherries (3.82 %), plums (3.65 %), etc. 15 % of the fruit plants and 54 % of grape vine plants in the system of official inspection of nursery control were category ācertifiedā
Nonlinear Resonant Jump in Rudder Positioning Electrohydraulic Systems
The rudder positioning electrohydraulic system, as many other complex systems, is a nonlinear
system. In nonlinear systems, a nonlinear resonant jump can occur. The paper deals with
the analysis of the rudder positioning electrohydraulic system regarding the nonlinear resonant
jump caused by saturation of the electrohydraulic proportional valve. The meaning of the term
āresonant jumpā is explained in the introduction. Then, the basics needs for occurrence of nonlinear
resonant jump phenomenon are given. The rudder positioning electrohydraulic system is also
described. Two methods of analyzing system with respect to resonant jumps are described: the
analytical method and the simulation method. When performing the analytical analysis based on
the describing function approach, the analysis of the variations of important parameters, including
saturation, is performed. Then, the confi rmation of the results of analytical analysis is illustrated
by the simulation method. Also, the simulation procedures, like creating an excitation signal and
accelerating the simulation by using vectors in Simulink/Matlab simulation software package, are
explained in detail
Supercritical CO2 extraction pilot plant design - towards IoT integration
Interes za tehnologije visokog tlaka tijekom posljednjih desetljeÄa se intenzivno poveÄava. Ekstrakcija super kritiÄnim fluidima (SFE) je process koji predstavlja alternative konvencionalnim postupcima separacije. U procesu ekstrakcije superkritiÄnim fluidima koristi se ekoloÅ”ki CO2 kao ekstrakcijsko otapalo zbog relativno niskog kritiÄnog tlaka (7,38 MPa), niske kritiÄne temperature (304 K), poželjnih svojstava i niske cijene. Tijekom ovog postupka, potrebno je rabiti visoke tlakove. Ekstrakcijska posuda (posuda pod tlakom) je najvažnija oprema sustava, gdje se trebaju ostvariti kritiÄni uvjeti i gdje se odvija ekstrakcija. TakoÄer, u procesu se treba obratiti pažnja i na druge dijelove ureÄaja (separator, izmjenjivaÄe topline, ventile i sl.) zbog uporabe visokih tlakova. Sigurnost je najvažniji factor kada se radi o SFE sustavima i projektiranje takve opreme s potpunom sigurnosti procesa predstavlja vrlo težak zadatak. Stoga, kako bi se postigla visoka razina sigurnosti, pouzdan sustav kontrole mora biti osmiÅ”ljen kao komunikacijski segment sustava kontrole i podataka. RazliÄiti procesni parametri, kao Å”to su protok CO2, tlak i temperature ekstrakcije, utjeÄu na process ekstrakcije i kvalitetu dobivenog ekstrakta. Stoga ovi parametri trebaju biti precizno kontrolirani i nadzirani tijekom ekstrakcije. Projektiranje jednog laboratorijskog-pilot postrojenja za ekstrakciju superkritiÄnim CO2, te razvoj daljinskog upravljanja i nadzora sustava prikazani su u ovom radu. Razvijeni sustavi SFE (mehaniÄke i elektriÄne komponente) usporeÄeni su s postojeÄim komercijalnim sustavima, gdje su prezentirane njegove glavne prednosti u odnosu na postojeÄe sustave. OmoguÄavanjem daljinskog upravljanja i nadzora klasiÄna kontrola procesa je spojena s konceptom Interneta objekata - Internet of Things (IoT), gdje informacija postaje sve prisutna u ogromnom podruÄju Interneta.The interest in high pressure technology during last decades increased intensively. Supercritical Fluid Extraction (SFE) is a process that is growing in importance as an alternative to conventional separation processes. SFE uses environmentally friendly CO2 as the extracting agent in the process because of its relatively low critical pressure (7,38 MPa), its low critical temperature (304 K), its non-dangerous character and low cost. During this process it is necessary to use high pressures in the procedure. The extractor vessel (pressure vessel) is the most important equipment of the system, where the supercritical conditions need to be established and the extraction occurs. Also other devices (separator vessel, heat exchangers, valves etc.) are necessary to be involved in the process due to used high pressures. Safety is the most important factor while dealing with SFE systems and the design of such equipment with full safety of process is very hard task. Therefore, to achieve the high desired safety level, a reliable control system must be designed as the control system and data communication segment. Various different process parameters such as CO2 mass flow rate, extraction pressures and temperatures affect the extraction process and the quality of the extract; hence these parameters need to be precisely controlled and monitored during the extraction. A design of one supercritical CO2 extraction laboratory-pilot plant and development of a remote control and its supervision system is presented in this paper. The developed SFE system (mechanical and electrical components) was compared with the existing commercial systems and its main advantages over the existing systems are presented. By enabling remote control and supervision the classical process control is joined with the concept of Internet of Things (IoT), where the information becomes omnipresent in the vast realm of Internet
Dizajn adaptivnog regulatora s neuronskim mrežama za regulaciju frekvencije u elektroenergetskom sustavu s toplinskim turbinama
This paper deals with analytical and simulation approach for choice of activation functions and instead of a number of nodes for a class of neural network controllers for frequency control of thermal power systems. Neural network update laws are derived via Lyapunov like stability analysis. When number of nodes is fixed, then simulation analysis is conducted to find the best performer activation function. Best performance is chosen using integral error criteria and proper statistical tests.Älanak opisuje analitiÄko-simulacijski pristup izboru aktivacijskih funkcija i broja Ävorova za klasu regulatora s neuronskim mrežama za regulaciju frekvencije u elektroenergetskom sustavu s toplinskim turbinama. Zakoni uÄenja neuronske mreže su izvedeni kroz analizu stabilnosti primjenom funkcije Ljapunova. Nakon Å”to je odre.en broj Ävorova, proveden je simulacijski postupak za odre.ivanje najbolje aktivacijske funkcije. Najbolja funkcija za dani regulator je odre.ena koriÅ”tenjem kriterija integralne pogreÅ”ke i statistiÄkim testiranjem
Production of fruit and vine seedlings material in the Republic of Croatia
U okviru Centra za sjemenarstvo i rasadniÄarstvo (nekada Zavod) pri Hrvatskoj agenciji za poljoprivredu i hranu kojeg je osnovala Vlada Republike Hrvatske 1998. godine kao nacionalno ovlaÅ”teno tijelo za nadzor i provoÄenje poslova iz podruÄja sjemenarstva i rasadniÄarstva, nalazi se i Odjel za rasadniÄarstvo. Od poÄetka svog djelovanja Odjel za rasadniÄarstvo provodi struÄni nadzor i nadzor pod struÄnom kontrolom nad proizvodnjom voÄnog i loznog sadnog materijala, vodi evidenciju na nacionalnoj razini o matiÄnim stablima i trsovima za proizvodnju voÄnog i loznog reprodukcijskog materijala te koliÄinama proizvedenih voÄnih sadnica i loznih cijepova prema vrstama, sortama, podlogama, kategorijama. PodruÄje nadzora proizvodnje sadnog materijala i izdavanje certifikata provodi se prema Zakonu u sjemenu, sadnom materijalu i priznavanju sorti poljoprivrednog bilja (NN 110/21) i prateÄim podzakonskim aktima.The Center (before the Institute) for Seed and Seedlings at the Croatian Agency for Agriculture and Food, was established in 1998 by the Government of the Republic of Croatia as a national competent authority for seed and seedlings certification. Since the beginning of its activity Department for planting material has been carrying out official certification and certification under official supervision of fruit and vine planting material. Department for planting material has been keeping records of fruit and vine mother plants and the quantities of fruit seedlings and vine grafts produced at the national level. Those records are kept according to species, varieties, rootstocks, categories of planting materiala. Official certification including certification under official supervision is carried out according to Official Controls Regulations (The Law on Seeds, Planting Material and Registration of Agricultural Plant Varieties,Official Gazette 110/21and its accompanying by-laws
PRIJEDLOG OPSEGA PODATAKA ZA MONITORING PROIZVODNIH JEDINICA U PRIMARNOJ REGULACIJI FREKVENCIJE
Stabilan pogon elektroenergetskog sustava temelj je za sigurnu i pouzdanu opskrbu potroÅ”aÄa elektriÄnom energijom. Frekvencija, kao mjera usklaÄenosti izmeÄu proizvodnje i potroÅ”nje elektriÄne energije, kljuÄan je parametar za osiguranje stabilnosti elektroenergetskog sustava. Sve proizvodne jedinice prikljuÄene na elektroenergetski sustav opremljene su sustavima za regulaciju djelatne snage i frekvencije, ÄeÅ”Äe zvanima turbinski regulatori. Turbinski regulatori reagiraju na promjenu frekvencije elektroenergetskog sustava na naÄin da reguliraju dotok pogonskog medija, pare ili vode, na turbinu agregata. Ovaj se regulacijski proces naziva primarna regulacija frekvencije. Primarna regulacija frekvencije osigurava brzu injekciju djelatne snage u elektroenergetski sustav u sluÄaju iznenadnog gubitka odreÄene koliÄine proizvodnje djelatne snage bilo gdje u elektroenergetskom sustavu, i posljediÄnog pada vrijednosti frekvencije. Monitoring sudjelovanja proizvodnih jedinica u primarnoj regulaciji frekvencije unapreÄuje mehanizme nadzora elektroenergetskog sustava i njegovih podsustava, a samim time i poveÄava sigurnost pogona elektroenergetskog sustava