Martin Fajman

Sorption characteristics of Amaranthus stems under storage conditions and water activity prediction.

Stems of amaranthus are considered as prospective biofuel in the Czech Republic. The study presents results of water sorption tests of this biomass in the range of 10-30 degrees C and water activity (a(w)) ranging from 0.4 to 0.99. The experimental procedure used was a gravimetric dynamic method. Four sorption models (Chung-Pfost, Halsey, Henderson, Oswin) were evaluated. The modified Hendersons equation was the best model for moisture adsorption and desorption of amaranthus stems. Critical values of equilibrium moisture content, corresponding to the a(w)=0.6, were 11.45% and 13.28%(wb) for water adsorption and desorption respectively, at the temperature of 20 degrees C. Heat of sorption (q(st)) was calculated using the chosen sorption model and Clausius-Clapeyron equation. An exponential function was found to fit the experimental q(st) values of amaranthus stems at moisture contents ranging from 7% to 40%(wb) for adsorption and desorption.

Tractor Pulling Tests Supported by Ecu Data Reading

Shrnutí Članek popisuje možnost využiti dat ze sběrnice CAN nebo ISO-BUS pro tahove zkoušky traktoru. Zkoušeni sestavalo z polnich a laboratornich zkoušek, před vlastnim polnim měřenim byl motor zkoušen na dynamometru. Parametry odečtene ze sběrnice CAN byly validovany externimi snimači a byla vyhodnocena jejich chyba. Na zakladě měřeni bylo shledano, že chyba prezentovaneho zatiženi odečteneho ze sběrnice CAN je velmi vyznamna. Pro zpřesněni teto hodnoty je nutne vytvořit regresni funkci. Model byl dale ověřen a byla vypočtena nejistota. Bylo shledano, že pro zahrnuti parametrů sběrnice CAN do testovacich procedur je nutne provest předchozi statistickou analyzu parametrů. Abstract The article describes the potential for using data from the CAN- or ISO- bus for tractor pulling tests. The testing techniques consisted of both field and laboratory tests; thus, each engine was tested in the laboratory before the field pulling tests. Values of CAN were validated by external instrumentation and their reliability with respect to the true values was analyzed. A significant degree of error was determined at low engine load; thus, for higher precision under the field conditions, it was necessary to use a regression function. The model was verified and its resulting uncertainty was calculated, which led to the conclusion that it is inadequate to take only the data from CAN into account if no further statistical processing is performed.

Design of a Powertrain Based on Synchronous Electric Drives Used in Vehicles

Shrnutí Članek pojednava o konverzi čtyřkoloveho vozidla pro volny čas se zažehovym motorem na pohon ryze elektricky. Snahou vyvoje bylo vytvořit konstrukčni řešeni bez vyznamnych zasahů do ramu vozidla. Byly zvažovany rozlične varianty instalace pohonu. Typicky způsob instalace je vyměna spalovaciho motoru za motor elektricky v původnim umistěni. Pomalu jedouci vozidla však mohou s vyhodou využivat take instalaci v rafku kola. Byly vytvořeny obě varianty. Pro zkoušeni vlastnosti obou variant byly vytvořeny zkušebni metodiky na valcovem dynamometru i v silničnim provozu. Hlavnim učelem zkoušeni bylo zejmena monitorovani elektrickych vlastnosti. Zaznamenavany byly hodnoty hnaci sily, rychlosti, vypočteneho vykonu, napěti i proudu. Důraz byl kladen i na stanoveni dojezdu z Li-Pol akumulatorů a spolehlivost systemu rekuperace. Abstract This paper deals with designing the conversion of a common on-road quad equipped with spark ignition engine to a pure electric drive. The aim of the development work was to create a design solution without making significant changes to the chassis. We considered several variants of powertrain installation. In general, two possibilities of electric drive design are used. Typically, the electric drive is mounted in place of an IC engine. Slow moving vehicles may have electric drives installed in the rims. We tested both variants. Therefore, to determine the properties of the mentioned variants we had to carry out simulation tests on a chassis dynamometer as well as road load tests. The main testing procedures consisted of driving cycles with the monitoring of electric parameters. Important values such as driving force, running speed, calculated power, battery voltage and used current were acquired. A fundamental part of the testing also consisted of monitoring the durability of the used Li-Pol batteries, and the reliability of the charging system with the support of regenerative braking.