Microprocessor-controlled autonomous source of constant current and voltage

Úlohou bakalářské práce je návrh a realizace spínaného zdroje pro konstrukci nabíječe olověných batérií 6/12 V řízenou mikroprocesorem. Je založený na snižujícím měniči napětí STEP-DOWN. První část prezentuje činnost měniče a vlastnosti olověných batérií, následovaná návrhem měniče pro danou aplikaci. Druhá část popisuje kritéria pro výběr jednotlivých součástek a jejich dimenzování. Výsledkem práce je simulace měniče v programu Micro-Cap 9 spolu s potřebnými výpočty, návrh zapojení zdroje s výpočtem tlumivky a metodami měření výstupních veličin. Nakonec je realizovaná deska plošného spoje spolu s několika měřeními a samotný ovládací program pro mikrokontrolér. Celý návrh a realizace je zaměřená na dosáhnutí co největší jednoduchosti zařízení a zároveň účinnosti a kvality nabíjení akumulátorů při nízkých nákladech na výrobek.The task of bachelor thesis is proposal of switching source for the construction of leadacid battery charger 6/12V controlled by microprocessor. It is based on buck converter of voltage. The first part presents the activity of converter and properties of lead-acid batteries, followed by a proposal of converter for a given application. The second part describes a criteria for selection of individual components and dimensioning them. The result of this thesis is simulation of converter in PC program Micro-Cap 9, along with the necessary calculations, a proposal of circuit with the calculation of inductor and methods of measurement of output quantities. Finally, is realized circuit board with a couple measurements and control program for the microcontroller. The entire proposal is focused to achieving the greatest simplicity of facility and efficiency and quality of charging accumulators together at low cost to the product.

Digital AM / FM transmitter

Táto diplomová práca je zameraná na teoretický popis aj praktickú realizáciu softwarovo definovaného vysielača. Hlavným zámerom práce bolo skonštruovať funkčný prototyp softwarovo definovaného vysielača v pásme FM. Teoretická časť je určená na popísanie základných častí zariadenia a princípov činnosti na pochopenie základného princípu digitálnych vysielačov a definovanie vhodnej súčiastkovej základne pre stavbu. Rozobraté sú používané typy A/D a D/A prevodníkov, bloky číslicového spracovania signálov a činnosti, ktoré tieto kompomenty vykonávajú. Druhá časť práce je zameraná prakticky. Špecifikované sú vhodné typy súčiastok, je navrhnutá bloková schéma, konkrétne zapojenie a navrhnutá doska plošného spoja v programe Eagle ako zásuvný modul pre vývojovú platformu Arduino. Ústredným bodom je riadiaci program, ktorého úlohou je celý vysielač nastaviť a riadiť. Ďalšou dôležitou časťou je impedančné prispôsobenie a vyladenie antény, ktoré je vysvetlené v praktickej časti práce. Výsledkom je funkčný prototyp softwarovo definovaného vysielača kompatibilný s platformou Arduino Uno.This master thesis is focused on the theoretical description and practical implementation of software defined transmitter. The main aim of this thesis was made the prototype of software defined transmitter in FM band. Theoretical part is determined to description of basic parts of equipment and working principles to understand the basic principle of digital transmitters and define the appropriate component base for construction. Discussed are used types of A/D and D/A converters, blocks of digital signal processing and the roles, which these components performs. The second part is focused practical. Specified are suitable types of components and block diagram is proposed for following electrical connection and printed circuit board in Eagle program as a plug-in modul for developmental platform Arduino. The main point is program, which sets and controls the transmitter. Next important part is impedance match and antenna tuning, which is explain in practical part of thesis. The result is prototype of software defined transmitter compatible with Arduino Uno platform.

Slump Loss of Concrete Based on RCA and Prepared by Specific Mixing Approach

Concrete is a dynamic material and its consistency changes with time, having impact on technological processes at working site. It is expressed due to slump loss - the reduction in slump from the time of original batching to the point when concrete is discharged from a truck mixer. Two kinds of additives (fly ash and recycled concrete powder) were tested to find their potential to improve the performance of recycled concrete aggregate in concrete, while the principle of triple-mixing method was adopted. Slump loss was evaluated based on measurements taken at 0, 45, and 90 minutes after mixing. The kind of aggregate, as well as kind of powdery material for coating the coarse fractions play significant role for the slump loss. Mixtures with fly ash as coating material achieved the biggest slump loss for both types of aggregate. The recycled concrete powder is well acceptable having similar impact on the slump loss as the cement has. When the NA is changed to RCA, the slump loss is higher and depends on material used for coating

Power restoration in medium voltage network using multiagent system

The article describes a novel approach to a power restoration in medium voltage power distribution network. It focuses primary at searching of a new network configuration enabling to minimalize the size of faulted area and to restore the power for the highest possible number of loads. It describes characteristic features of medium voltage power distribution network and discusses the implementation of the presented approach in existing networks. A software tool, developed by the authors, including physical simulation of model network and its autonomous control system is described. An example of fault situation in a virtual distribution network is presented. Afterwards, the solution of restoration problem by proposed multiagent system is simulated using the software tool described in the paper

Characterization of Sludge From Iron Ore Processing and Properties of Mortar Prepared by Full Replacement of Natural Silica Sand

This paper focuses on the use of sludge, which is currently a landfilled sand-like material left over from the processing of iron ore (IOP), representing an environmental burden. The incorporation of the material into some building mixtures like mortar or concrete can bring both environmental and technical benefit through the improvement of some properties of final mixture. Through the realization of the experiment programme, the authors have contributed to the knowledge about IOP and have determined the impact of this material on the properties of mortar mixture. This material is characterized using chemical, mineralogical, and granulometric analysis and then applied as 100% replacement of silica sand in standard mortar mixture. Basic physical-mechanical parameters (water demand, flexural strength, compressive strength) were tested. For the strength characteristics, both the samples with IOP sludge and samples with standardized sand (reference sample) were subjected to testing for a long-term period (14, 28, 270, and 365 days). Moreover, the capillary moisture was measured for 28-day old samples. Mortar prepared with IOP sludge shows lower compressive strength compared to the reference mixture throughout the overall time development, although the values themselves are sufficient for practical application. The flexural strength was found to be even better. The performance of the IOP sludge can be deemed as promising for practical applications when used in cement mortar

Study of casting and solidification of slab ingot from tool steel using numerical modelling

The main problem in the production of forgings from tool steels, especially thick plates, blocks, pulleys and rods which are used for special machine components for demanding applications, it is the inhomogeneous structure with segregations, cracks in segregations or complex type of non-metallic inclusions MnS and TiCN. These forgings are actually produced from conventional forging ingots. Due to the size of forgings, it would be interesting the production of these forgings from slab ingots. It is possible that the production of forgings from slab ingots (which are distinguished by a characteristic aspect ratio A/B), it would reduce the occurrence of segregations. The paper presents the verification of the production process of slab steel ingots in particular by means of numerical modelling using finite element method. The paper describes the pre-processing, processing and post-processing phases of numerical modelling. The attention was focused on the prediction of behavior of hot metal during the mold filling, on the verification of the final porosity, of the final segregation and on the prediction of risk of cracks depending on the actual geometry of the mold.Web of Science6042885287

Hodnotenie konkurencieschopnosti slovenského strojárskeho priemyslu v kontexte EÚ

Príspevok bol riešený v rámci projektu KEGA 019TUKE-4/2022 Príprava manažérov nových výrobných štruktúr budúcnosti na princípoch „Overall Equipment Effectiveness“ (OEE) prostredníctvom vzdelávania študentov v predmete Manažment výroby v študijnom programe Priemyselné inžinierstvo a VEGA 1/0438/20 Interakcia digitálnych technológií za účelom podpory softvérovej a hardvérovej komunikácie pokročilej platformy systému výroby.V súčasnej dobe globalizácia predstavuje neodvratnú realitu a konkurencia na trhu stále narastá. To predstavuje pre podniky a priemyselné odvetvia riešenie problému konkurencieschopnosti a jej zabezpečenia. Dnes sa trhy stále viac otvárajú a medzinárodná konkurencia sa zintenzívňuje, je pre mnohé odvetvia priemyslu kľúčové udržať si konkurencieschopnosť. Slovenský strojársky priemysel predstavuje významnú časť národného hospodárstva a jeho konkurencieschopnosť na trhoch Európskej únie je kritická pre udržanie významného postavenia na týchto trhoch

Današnje stanje međulonca s pokrivnim troskama u ljevaonici slabova

Tundish metallurgy development, which has been focused on steel cleanliness improvement in last few years, affected also tundish slag systems. Molten slags are the most suitable for both absorbing and refining functions of tundish cover slags, while a system of extremely low density does satisfy their isolating functions in the best way. Hence it is obvious, that it is not possible to assure the main functions using one sort of tundish covering slags. In addition, traditional acid slags, are being replaced with basic covering slags, or combination of both types. In this work, we have tried to investigate the operation of tundish covering slag under the condition of slab continuous casting. A genesis of covering slag from applied cover powders its refining functions have been investigated, as well as the changes of covering slag chemical composition during one tundish casting sequence.Razvoj metalurgije međulonca koji se usmjerio na unapređivanje čistoće čelika tijekom zadnjih nekoliko godina odrazio se i na vrste troske u međuloncu. Rastaljena troska je najpogodnija kako za funkcije apsorbiranja tako i za funkcije rafiniranja pokrovne troske međulonca sve dok sistem krajnje male gustoće zadovoljava na najbolji način njene izolacione funkcije. Iz toga je jasno, da nije moguće osigurati glavne funkcije uporabom samo jedne vrste pokrovnih troski međulonca. Osim toga, tradicionalne kisele troske zamjenjuju se bazičnim pokrovnim troskama, ili se koristi kombinacija obadva tipa. U ovom članku se nastojalo istražiti rad pokrovne troske međulonca u uvjetima kontinuiranog lijevanja slabova. Istraživano je kako se uporaba pokrovne troske razvijala iz uporabe pokrovnih prahova te njene funkcije rafiniranja kao i promjene njenog kemijskog sastava tijekom jednog ciklusa lijevanja međulonca

Pročišćavanje čelika optimiranjem konfiguracije međulonca

In continuous casting process, liquid steel flows through the tundish, which is supposed to operate as a continuous refining finisher. To provide a functionality of such a device, a pack of tundish metallurgy techniques must be applied, whose efficiency is conditioned especially with optimal symmetrical and dynamical melt flow. Flow optimizing can be achieved through the shaping of inside tundish configuration, using flow control devices such as turbulence inhibitors, impact pads, baffles, weirs, dams, etc. The theme of the present paper is the precise employment of a turbulence inhibitor, commercially known as TURBOSTOPTM, together with a pair of baffles & a flat impact pad in slab custer to improve steel cleanliness and a fluid flow phenomenon in a two strands tundish.Tijekom procesa kontinuiranog lijevanja tekući čelik prolazi kroz međulonac koji funkcionira kao kontinuirani uređaj za završnu doradu rafiniranjem. Za osiguranje funkcioniranja takvog uređaja mora se primijeniti tehnika metalurgije međulonca čija učinkovitost je uvjetovana naročito optimalnim simetrijskim i dinamičkim tečenjem taline. Optimalizacija protoka se može postići oblikovanjem unutrašnje konfiguracije međulonca uporabom takvih uređaja za kontrolu protoka kao što su inhibitori turbulencije, zadebljanje za ublažavanje udaraca, pregradne ploče, brane itd. Tema ovog rada je točna primjena inhibitora turbulencije poznatog pod trgovačkim nazivom TURBOSTOPTM, zajedno s parom skretnih pregrada i ravnim zadebljanjem za ublažavanje udaraca u lijevanom slabu radi poboljšanja čistoće čelika i fenomena toka fluida u dvije žile međulonca

Composition related electrical active defect states of InGaAs and GaAsN

This paper discusses results of electrically active defect states - deep energy level analysis in InGaAs and GaAsN undoped semiconductor structures grown for solar cell applications. Main attention is focused on composition and growth condition dependent impurities and the investigation of their possible origins. For this purpose a widely utilized spectroscopy method, Deep Level Transient Fourier Spectroscopy, was utilized. The most significant responses of each sample labelled as InG2, InG3 and NG1, NG2 were discussed in detail and confirmed by simulations and literature data. The presence of a possible dual conduction type and dual state defect complex, dependent on the In/N composition, is reported. Beneficial characteristics of specific indium and nitrogen concentrations capable of eliminating or reducing certain point defects and dislocations are stated