1,549 research outputs found

    Preparation for function demonstration of basic types of oscillators

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    Tato bakal├í┼Ösk├í pr├íce v ├║vodu pojedn├ív├í o z├íkladn├şch typech oscil├ítor┼» a jejich roz─Źlen─Ťn├ş do skupin podle charakteru zapojen├ş. Pro praktickou realizaci p┼Ö├şpravku bylo vybr├íno ─Źty┼Ö r┼»zn├Żch druh┼» zapojen├ş. Byl proveden n├ívrh ├║pln├Żch obvodov├Żch zapojen├ş. Funkce n├ívrhu byla n├ísledn─Ť ov─Ť┼Öena simulac├ş na PC programem OrCAD PSpice. N├ívrh zahrnuje mo┼żnost ┼Ö├şzen├ş p┼Ö├şpravku pomoc├ş PC s mo┼żnost├ş p┼Öep├şn├ín├ş v├Żstup┼» a lad─Ťn├şm kmito─Źtu.Bachelor's thesis deals with basic types of oscillators. Oscillators were divided into groups in the introduction. For the practical implementation was chosen four different types of oscillators. For each type of selected oscillator was done circuit design. Subsequently, the design was simulated by PC software OrCAD PSpice. The proposal includes a possibility of the control device by switching between outputs and tuning oscillator's frequency.

    Iskorištavanje otpadne topline iz cementare sustavom ORC

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    U radu je okvirno razra─Ĺen potencijal ugradnje ORCa za iskori┼ítavanje otpadne topline iz pogona cementare Holcim u Koroma─Źnom. Opisani su principi rada cementare i organskog Rankineovog ciklusa. Postavljen je matemati─Źki model za prora─Źun ciklusa, a kori┼íten je program Excel. Za odre─Ĺivanje stanja tvari kori┼ítene su pozivne funkcije iz programa miniREFPROP. Optimizacija je provedena upotrebom Excelovog alata Solver. \Na kraju rada dani su rezultati za radne fluide R134a i R123 sa i bez upotrebe regeneratora. Kao rashladni spremnik odabrana je morska voda zbog blizine obale mora, a za posrednika izme─Ĺu dva izvora topline i ORCa odabrano je termalno ulje Terminol 66

    Analysis of Exergy Destruction of an Evaporator or/and a Condenser

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    This paper presents the exergy destruction of an evaporator or a condenser or evaporator and condenser. The exergy destruction can be analytically calculated by using the same non-dimensional variables which have been used by its energy analysis. The one additional variable is the ratio of absolute input temperatures of both streams. This means that the given model enables the simultaneous calculation of heat transfer effectiveness and exergy destruction respectively. The exergy destruction is put in the ratio to the heat capacity of the weaker stream. The limited values of the exergy destruction are estimated, taking into account the zero and infinite values of relevant variables. Further, exergy destruction for the case when both streams change phase is calculated, which means that the appropriate heat exchanger is condenser and evaporator simultaneously. The given model is derived as a special case of the model for calculation of exergy destruction by parallel and counter flow heat exchangers respectively. For all presented cases the only temperature differences between the streams have been taken into account. This means that the effect of a frictional pressure drop of the streams on exergy destruction has been neglected

    Energy and Exergy Efficiency Analysis of Sealing Steam Condenser in Propulsion System of LNG Carrier

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    In ship propulsion systems today diesel engines are dominant, but steam propulsion systems prevail in one type of ships and that are LNG carriers. Such steam propulsion systems consist of many different components. One interesting component of these systems is sealing steam condenser analysed in this paper. Measurements of all necessary operating parameters for analysed sealing steam condenser were performed during the ship exploitation and they were used for calculating the energy and exergy efficiency of this device. Except the displayed movement of both efficiencies the reasons for those changes and proposals for possible improvements were presented. Also, it was displayed all operating parameters of sealing steam condenser that has an impact on its performance and efficiency. During the ship exploitation, improvements related to the sealing steam condenser efficiency are hard to expect because improvements would cause an increase in the steam propulsion system operating costs

    Spiralni izmjenjiva─Źi topline u kompaktnim parnim toplinskim stanicama

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    Kompaktne parne toplinske stanice sa spiralnim izmjenjiva─Źima topline predstavljaju funkcionalno zaokru┼żenu cjelinu sustava daljinskog grijanja kod kojeg je nositelj topline pregrijana vodena para. Upravo zbog kompaktne izvedbe one predstavljaju novi, jednostavniji i povoljniji pristup projektiranju i monta┼żi parnih toplinskih stanica. U radu se najprije op─çenito govori o sustavima daljinskog grijanja te toplinskim stanicama kao jednim od glavnih komponenata sustava. Zatim se pobli┼że konstrukcijski i funkcionalno predstavljaju toplinske stanice u kompaktnoj izvedbi te spiralni izmjenjiva─Źi topline kao njihovi sastavni dijelovi. Nadalje, u radu se prikazuje metodologija termodinami─Źkog prora─Źuna spiralnih izmjenjiva─Źa topline koji rade u funkciji kondenzatora unutar parnih toplinskih stanica. Isto tako, navedeni su izrazi za koeficijente prijelaza topline koji se koriste prilikom termodinami─Źkog prora─Źuna. Poseban naglasak je stavljen na odabir termodinami─Źkog modela za izra─Źun koeficijenta prijelaza topline prilikom filmske kondenzacije vodene pare unutar spiralnih cijevi

    Step-up DC/DC converter controlled by microcontroller

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    Obsahem bakal├í┼Ösk├ę pr├íce je p┼Öed─Ťl├ín├ş zvy┼íuj├şc├şho DC/DC m─Ťni─Źe z analogov├ęho ┼Ö├şzen├ş na digit├íln├ş pro firmu RADAN s.r.o. Tento projekt obsahuje srovn├ín├ş dvou sp├şnan├Żch zdroj┼» a jejich mo┼żnost ┼Ö├şzen├ş, zm─Ťna p┼»vodn├şho analogov├ęho zdroje na ─Ź├íst ┼Ö├şzenou mikrokontrol├ęrem.The content of the bachelorÔÇÖs thesis is the remaking of increasing DC/DC converter from analog to digital management for the company RADAN s.r.o. This project includes a comparison of the two switching power supplies and their ability to control, change the original analog sources to part controlled by a microcontroller.

    Dynamic RAM Technology and migration to DDR4 Standard

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    Memory devices play a substantial role in developing increasingly fast computer systems. Most computers use a memory hierarchy consisting of different memory types with different features. This thesis examines dynamic random access memory (DRAM), which is used as the main memory. It looks at some fundamental features of computer memory technology and explains the structure and principle of operation of DRAM devices. A major focus is on synchronous dynamic random access memory (SDRAM) and on distinctions between evolutionary double-data rate SDRAM devices. Their high capacity is mainly due to a prefetch register and burst transfer. The thesis also explores various innovations and techniques designed into the new DDR4 SDRAM device leading to performance and power advantages

    THE OPTIMIZATION OF THE STEAM PLANT BY MEANS OF AN ENGINE ROOM SIMULATOR

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    U radu je prikazano optimiranje parnoturbinskog pogonskog postrojenja na brodu za prijevoz ukapljenog prirodnog plina. Izvr┼íena je analiza pogonskih radnih parametara te su na simulatoru brodske strojarnice simulirane situacije koje utje─Źu na iskoristivost postrojenja. Izvr┼íene simulacije na simulatoru LNG broda omogu─çile su pra─çenje promjene radnih parametara pri pojavi ne┼żeljenih i neo─Źekivanih stanja za koje postoji vjerojatnost pojavljivanja unutar funkcionalnog realnog sustava. Na taj na─Źin je mogu─çe bolje dijagnosticirati gre┼íke unutar realnog sustava te odrediti optimalno pona┼íanje pojedinih elemenata sustava. Kod generatora pare analiziran je utjecaj pojave ─Źa─Ĺe na cijevima zagrija─Źa vode i pregrija─Źa pare na potro┼ínju goriva, te utjecaj izgaranja razli─Źitih goriva na emisiju NOx. Kod parne turbine analiziran je utjecaj istro┼íenosti odrivnog le┼żaja turbine i istro┼íenosti lopatica niskotla─Źne turbine na snagu, aksijalni pomak i na pojavu vibracija turbine. Dobiveni rezultati pokazuju da primjena simulatora mo┼że poslu┼żiti brodarskim kompanijama i pomorskim edukacijskim ustanovama za uvje┼żbavanje pomoraca i studenata za rad u razli─Źitim okolnostima te za brzo i u─Źinkovito reagiranje u kriti─Źnim situacijama.The optimization of the steam propulsion plant on LNG tankers is dealt with in this paper. The operational parameter analysis was performed and the situations influencing the plant efficiency were simulated on the engine room simulator. The performed simulations on the LNG simulator module enabled monitoring of the operational parameters change in undesirable and unexpected conditions for which there is a probability to occur within the operational system. In such a way an enhanced diagnostics of failures within a real system and the determination of the optimal performance of individual components are possible. The boiler analysis has concentrated not only on the influence of soot deposit on the economizer and superheater piping to the fuel consumption but also on the influence of burning different fuels to NOx emission. Another analysis has been carried out in the main turbine in which the influence of worn out thrust bearing and low-pressure turbine blades to the turbine output, axial displacement and vibrations was analysed. The results have shown that the simulator can serve the shipping companies and maritime educational institutions to train the students and seafarers for working in various situations and to prepare them to respond to emergencies promptly and efficiently

    Vodom hla─Ĺeni kondenzator

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    U ovom radu konstruirani su Shell&Tube i plo─Źasti vodom hla─Ĺeni kondenzatori za parametre zadane u programskom zadatku. Prilikom konstruiranja Shell&Tube izmjenjiva─Źa provedeni su termodinami─Źki, hidrauli─Źki i prora─Źun ─Źvrsto─çe, dok su kod plo─Źastog izmjenjiva─Źa provedeni termodinami─Źki i hidrauli─Źki prora─Źun. U radu su prikazani razli─Źiti izrazi za izra─Źun koeficijenta prijelaza topline i pada tlaka tijekom potpune kondenzacije. Ti izrazi su zatim uspore─Ĺeni za zadane po─Źetne uvjete i s parametrima izra─Źunatim tijekom konstruiranja izmjenjiva─Źa. Provedena je i financijska analiza kroz vremenski period, gdje su uspore─Ĺeni investicijski i pogonski tro┼íkovi za oba tipa izmjenjiva─Źa
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