217 research outputs found
Capturing sets of ordinals by normal ultrapowers
We investigate the extent to which ultrapowers by normal measures on
can be correct about powersets for . We
consider two versions of this questions, the capturing property
and the local capturing property
. holds if there is
an ultrapower by a normal measure on which correctly computes
. is a weakening of
which holds if every subset of is
contained in some ultrapower by a normal measure on . After examining
the basic properties of these two notions, we identify the exact consistency
strength of . Building on results of Cummings,
who determined the exact consistency strength of
, and using a forcing due to Apter and Shelah, we
show that can hold at the least measurable
cardinal.Comment: 20 page
Determination of moisture ratio in parts of the hop cone during the drying process in belt dryer
ArticleThe
paper deals with monitoring the moisture content of hop cones and their parts
(strigs and bracts) in PCHB 750 hop belt dryer. When drying hop cones, the critical point is the
sufficient drying of the strig. These are therefore dried to a moisture content o
f 6 to 8%. This
exact moisture provides a sufficient guarantee ensuring that the strig is dried up. On the other
hand, bracts are dried up to such a level which makes pressing the hops impossible. Therefore,
after drying, the bracts are remoistened. This i
s called hops conditioning. After conditioning the
moisture content of hops is optimal, ranging between 8 and 11%. There is no doubt that drying
or any further moistening
does not benefit the hop cone.
During the experiment, the moisture content was determ
ined regarding the whole hop cones as
well as the bracts and strigs separately, the samples of which had been taken from the hops prior
to entering the dryer, from different parts of belts in the dryer and subsequently before and after
the conditioning. Th
e moisture content was determined by means of Mettler HE53 moisture
analyzer. After the bracts and strigs had been dried, we calculated their weight ratio which was
approx. 90% of bracts and 10% of strigs. Based on this ratio the weighted average was calcu
lated
which corresponds to the moisture
content of the whole hop cone.
The measured values indicate that the average moisture content of hops below 10% was already
at the beginning of the third belt of the dryer. The hops had been unnecessarily overdried a
long
the whole third belt. Another output refers to the moisture ratio of hop cones, bracts and strigs in
different parts of the dryer. The obtained values will serve as a basis for the follow
-
up design of
a device for monitoring the dryer parameters and i
ts visualisation
Critical velocity of solid mineral fertilizers in a vertical upward airstream and repose angle
ArticleCritical velocity of mineral fertilizers in airstream is important not only at the
application of fertilizers by spreaders but also at combine of fertilizing and sowing. The
knowledge of angles of repose is important to design hoppers on spreaders for solid mineral
fertilizers. Critical velocities for six solid mineral fertilizers were measured in the vertical
aspiration duct of a laboratory sorting machine. Variation curves were constructed for particular
fertilizers and the mean critical velocity of fertilizers (velocity of uplift) was computed. The mean
critical velocity of fertilizers was between 8.53 and 12.43 m s
-1
. The lowest critical velocity was
found out in the fertilizer UREA 46%, the highest in the fertilizer LAV. Statistical significance
of differences in the critical velocity of fertilizers was assessed. Angles of repose of eight solid
mineral fertilizers were also measured and statistical significance of differences was evaluated.
The highest values of repose angle were determined for potassium salt and ammonium sulfate
(35.9° respectively 34.9°), the lowest values for UREA and LAV (28.7° respectively 29.6°). The
obtained results extend information applicable to an assessment of parameters of the operation
quality of spreaders during mineral fertilizer application
Effect of rotors on the parameters of hop drying in belt dryers
ArticleThis article contains a design and verification for a technical solution aimed at
optimising the hop drying process in belt dryer and at increasing the quality of the final product.
Above the first belt of our belt dryer two evenly distributed double-arm rotors were installed and
tested in operation to improve the permeability of the drying air through a flattened hop layer, as
well as to improve the speed of drying. The measurements carried out in operation and comparing
the drying process with the rotors switched on and off concluded that by inclusion of rotors the
hop layer becomes more permeable, and when switched on, the rotors have a positive effect on
faster reduction of the relative humidity and on increase of the drying air temperature. With rotors
switched on, the percentage drop in the drying air relative humidity at the third inspection window
of the first belt, compared to the first inspection window, was 41% on average (values obtained
from data loggers and fixed sensors), the drying air temperature increased by 29%, and the hop
moisture content decreased by 12%. Whereas with rotors switched off, the drop in the drying air
relative humidity was only by 26% on average, the drying air temperature increased only by 14%,
and the hop moisture content decreased by 12%. Based on long-term monitoring of fuel
consumption during the whole harvesting season starting 2011 until 2017 inclusive, the average
annual consumption of LFO (2011–2014) results in 494 L t
-1 operating without rotors, and
431 L t
-1 when operating with rotors (2015–2017). This implies that due to the implementation of
rotors, the fuel saving being 13% is significant
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