Some Relationships Between Malted Barleys of Different Nitrogen Levels and the Wort Properties

Barleys containing different levels of total nitrogen seem to have similar initial patterns for endosperm modification during malting. The higher nitrogen barley had a slower rate of endosperm modification, whilst the lower nitrogen barley had a faster rate of endosperm modification as germination progressed. Although the higher nitrogen barley had slower rate of endosperm modification, it transferred more nitrogen materials to the roots and shoots, whilst the lower nitrogen barley transferred less nitrogen materials to the roots and shoots. The higher nitrogen barley produced a lower yield of extract, but released higher levels of soluble nitrogen, free amino nitrogen (FAN) and peptides in the extract. The lower nitrogen barley produced a higher yield of extract and higher levels of carbohydrates (reducing sugars) in the extract. These results suggest that other important relationships exist between barleys of different nitrogen content. A drop in peptide nitrogen occurred on the same day of germination in both barley samples.     

A multi-port D-R mutator using CCIIs with current followers

A multi-port D-R mutator with new current conveyors (CFCCIIs) as the four-port active element is proposed. Each CFCCII consists of a current follower added to a second-generation current conveyor (CCII). This proposed circuit is a simple configuration using CCIIs, CFCCIIs and grounded capacitances and is applied to higher order high-pass filters. This configuration can realize a superior transmission characteristic, inheriting the characteristic of the conventional LC filter. Since all the passive elements are grounded, the influence of parasitic elements of current conveyors can be reduced with this circuit configuration. As a result, this circuit is considered a suitable configuration for monolithic integration. Results obtained from the SPICE simulations show the realized filters have excellent performance and the circuit is effective.     

Cascaded Common Nodal Point Multi-level Inverter Topology

Recent trends in the multi-level inverter (MLI) technology demand reduced number of switches, driver circuits, isolated DC sources, peak inverse voltage (PIV), appreciable number of voltage level, and lower total harmonic distortion. This paper presents an improved cascaded MLI configuration. Each module comprises ten switches, two isolated DC sources, and two capacitors; it can generate a maximum of 9-level output voltage waveform. Optimized switching sequence is developed that ensures minimum switching transitions and is implemented through single-carrier pulse width modulation for the control of the proposed topology. The classical cascaded H-bridge inverter and some recently developed MLI configurations were compared with the proposed inverter circuit. Results show that the proposed inverter configuration generates high number of output voltage levels with reduced number of power switches and PIV. It also has a lower per-unit power loss profile. Unit capacitor voltage balancing scheme is developed, which ensures proper control of the unit step voltage level in each of the cascaded modules, at extreme loading condition. For two cascaded inverter modules, simulation and experimental verifications are carried out on the proposed inverter for an R–L load. Simulation results of the output voltage waveforms and its harmonic spectrum are in conformity with experimental results.     

Moisture Diffusivity Coefficient and Convective Drying Modelling of Murta (Ugni molinae Turcz): Influence of Temperature and Vacuum on Drying Kinetics

In this study, murta (Ugni molinae Turcz) or murtilla berries were dried in single layer at air temperatures of 50, 60 and 70 °C under vacuum and atmospheric pressure conditions. The effect of drying air temperature and vacuum on the basic dehydration characteristics of murta was determined. For the kinetic modelling, ten mathematical expressions were fitted to the experimental data. Kinetic parameters and diffusion coefficients as evaluated by an Arrhenius-type equation, showed temperature dependency. Fick’s second law was used to calculate the effective moisture diffusivity that varied from 3.10 to 11.27?×?10^?10 m²/s and from 5.50 to 11.30?×?10^?10 m²/s with activation energy values of 59.27 and 34.30 kJ/mol for atmospheric pressure and vacuum drying, respectively. According to the statistical tests applied, the Midilli–Ku?uk model obtained the best-fit quality on experimental data, followed closely by the Weibull distribution model, the Page and the modified Page models.     

Performance of Husked,Acid Dehusked and Hull‐less Barley and Malt in Relation to Alcohol Production

Studies carried out on normal husked barley, normal hull‐less (naked) barley, acid dehusked barley and acid dehusked hull‐less barley, as well as the malts derived from them, showed that when acid dehusked barley samples (obtained from either husked or hull‐less barley), were processed using commercial enzyme preparations, they produced more alcohol when compared with the alcohol yield obtained from the barley samples from which the acid dehusked samples were derived. When the husked (Optic) control, acid dehusked and hull‐less barley samples were malted, Optic control barley produced malt that gave higher dextrinising units (DU) and diastatic power (DP), whilst acid dehusked Optic and hull‐less barley produced malts that gave similar DU results on day 5 of the germination time. When mashed, acid dehusked (Optic) barley malt produced wort that filtered faster than the wort obtained from the malt made from hull‐less barley. This observation is very important because it shows that the husk of the barley is not the only factor that determines the filtration performance of the malted barley, since both the malt samples made from husked and acid dehusked barley had similar filtration rates on day 5 of the germination time. The slow filtration rate observed for the wort made from hull‐less barley suggests that other factors play some role during the filtration of the mash made from hull‐less barley malt. Although hull‐less malt appeared to develop lower DU and DP enzyme activities, when compared with the values obtained for the Optic control, hull‐less barley malted faster and produced optimum predicted spirit yield (PSY) at day 4 of the germination time. In contrast, the control husked Optic barley malt that had higher DU and DP produced equivalent (optimum) predicted spirit yield one day later at 5 days germination time. This is an advantage for hull‐less barley, both in terms of time and energy saving during the malting of barley. Although the acid dehusked Optic barley produced more alcohol than the husked control when commercial enzyme preparation was used to process barley, it was surprising that when the derived malt was assessed, it gave a lower predicted spirit yield than the husked control, even though it produced a higher amount of hot water extract (HWE). The higher extract yield and lower predicted spirit yield obtained from the malt made from acid dehusked malt confirmed that high extract yield is not necessarily associated with high fermentable extract.     

Digital system for 1/f fluctuation-speed control of asmall-fan motor

To produce a comfortable breeze similar to a natural one, a digital open-loop control system was utilized to control the speed of a small fan motor with 1/f fluctuation. The system was modeled as a first-order lag element with a time constant of 1.1 s. The output was controlled by commands and produced 1/f fluctuations, even though it was an open-loop system when the holding time of the data for 1/f fluctuation was set at more than 2 s