Metrological Prerequisites for Determination of Silage Density Compacted in a Bunker silo using Gamma Rays

In order to produce high quality silage feed it is particularly important to appropriately compact the chopped material upon storage. It was the objective of the research to understand the metrological prerequisites for online density measuring, using a radiometric probe. Caesium 137 with an activity of 37 MBq was used as radiation source in the tests. Source and detector were hovered over the goods to be measured. The number of gamma photons reflected from the goods occurs to be proportional to the density of the silaged goods. The probe was tested in a compaction test arrangement on chopped grass and maize, as well as on different bulk goods. It could be shown that radiometric measuring devices are suitable to measure the density of agricultural goods, particularly ensiled goods, using back-scattering. The measuring built the basis for the development of a probe which shall be deployed on horizontal silos in the future

Dimension- and space-based intertrial effects in visual pop-out search: modulation by task demands for focal-attentional processing

Two experiments compared reaction times (RTs) in visual search for singleton feature targets defined, variably across trials, in either the color or the orientation dimension. Experiment 1 required observers to simply discern target presence versus absence (simple-detection task); Experiment 2 required them to respond to a detection-irrelevant form attribute of the target (compound-search task). Experiment 1 revealed a marked dimensional intertrial effect of 34ms for an target defined in a changed versus a repeated dimension, and an intertrial target distance effect, with an 4-ms increase in RTs (per unit of distance) as the separation of the current relative to the preceding target increased. Conversely, in Experiment 2, the dimension change effect was markedly reduced (11ms), while the intertrial target distance effect was markedly increased (11ms per unit of distance). The results suggest that dimension change/repetition effects are modulated by the amount of attentional focusing required by the task, with space-based attention altering the integration of dimension-specific feature contrast signals at the level of the overall-saliency ma

An aeroacoustic investigation into the effect of self-oscillating trailing edge flaplets

The aeroacoustics of a NACA 0012 aerofoil with an array of self-oscillating flexible flaplets attached on the trailing edge has been investigated at low to moderate chord based Reynolds number (50,000 -- 350,000) and at geometric angles of attack from $\alpha_g = 0^\circ$ -- $20^\circ$. When the aerofoil is untripped, tonal peaks are observed on the baseline aerofoil. When the passive flaplets are attached to the pressure side of the aerofoil, the tonal peak is removed. If the flaplets are then placed on the suction side, the tonal peak is reduced, but not removed. It is therefore hypothesised that the flaplets on the pressure side modifies the laminar separation bubble situated on the pressure side of the aerofoil, a key mechanism for tonal noise. Throughout all cases, both tripped and untripped, a low frequency (0.1 kHz -- 0.6 kHz) noise reduction and a slight increase at higher frequencies (>2 kHz) is seen. This gives an average overall sound pressure level (OSPL) reduction of 1.5 -- 2 dB for the flaplets affixed to the pressure side. The cases where the tonal noise component is removed an OSPL reduction of up to 20 dB can be seen

Role of facilitatory and inhibitory short-term memory mechanisms for the guidance of visual search

In the visual search paradigm, participants’ task is to detect the presence or absence of a target item, which is presented in an array of distractor items. Usually it is found that performance is dependent on specific properties of the visual display, for example, the number of items to be searched or the similarity between display items. However, recent research has demonstrated that memory mechanisms can also affect search behaviour. Further, it was found that memory mechanisms can, in principle, be either facilitatory or inhibitory, that is, that the processing of the item locations, features, or search objects themselves can be improved or impeded, respectively. This thesis investigated the effects of (1) facilitatory and inhibitory memory mechanisms based on the element positions within the search display; (2) facilitatory memory mechanisms based on the features of the search elements; and (3) inhibitory memory mechanisms based on the search objects themselves

Multisensory visuo-tactile context learning enhances the guidance of unisensory visual search

Does multisensory distractor-target context learning enhance visual search over and above unisensory learning? To address this, we had participants perform a visual search task under both uni- and multisensory conditions. Search arrays consisted of one Gabor target that differed from three homogeneous distractors in orientation; participants had to discriminate the target's orientation. In the multisensory session, additional tactile (vibration-pattern) stimulation was delivered to two fingers of each hand, with the odd-one-out tactile target and the distractors co-located with the corresponding visual items in half the trials; the other half presented the visual array only. In both sessions, the visual target was embedded within identical (repeated) spatial arrangements of distractors in half of the trials. The results revealed faster response times to targets in repeated versus non-repeated arrays, evidencing `contextual cueing'. This effect was enhanced in the multisensory session---importantly, even when the visual arrays presented without concurrent tactile stimulation. Drift--diffusion modeling confirmed that contextual cueing increased the rate at which task-relevant information was accumulated, as well as decreasing the amount of evidence required for a response decision. Importantly, multisensory learning selectively enhanced the evidence-accumulation rate, expediting target detection even when the context memories were triggered by visual stimuli alone

The evaluation of potential improvements of barton pot oxides for lead acid batteries

Lead Oxide (PbO) is the main material used for the preparation of the active material for the positive and negative electrodes in the lead acid battery where the electrochemical reaction that provides the electrical energy of the battery takes place. The particle size distribution and surface area characteristics of the lead oxide play a major role in the electrical performance of the completed battery. The two most commonly used processes to manufacture PbO in the lead acid battery industry are the Barton pot and the Ball mill processes. These two processes produce oxides that differ in particle size distribution, particle shape and surface area. It is generally accepted that the Ball mill process produces an oxide with a smaller mean particle size with a higher surface area and better initial electrical performance than the Barton pot process to the detriment of an initial higher capital and running cost. The study showed that it is possible to improve the surface area and particle size distribution characteristics of Barton pot oxide, by subsequently hammer milling the oxide particles before the paste manufacturing process. The results showed that there was an initial reduction in the particle size with an increase in the surface area. This increased the electrochemical performance in terms of the high rate discharge. However, further hammering of the oxide reduced the average particle size only slightly with little change in the surface area and a reduction in the electrochemical performance. The study showed that an improvement in Barton pot oxide can be achieved with a hammering of the oxide in order to obtain a uniform particle size with improved surface area and an improved high rate performance of the electrochemical cells made with such an oxide. As a comparison, the particle size and surface area characteristics of Ball mill lead oxide subjected to the hammer milling process was also studied. The results showed a similar effect to the Barton pot oxide on the particle size distribution. However, there was no appreciable change in the surface area due to the hammer milling process

Radiometric density measurement for silage compaction in bunker silos

Certain minimum densities should be targeted when storing silage in bunker silos.  However, farmers lack facilities to measure the actual density and then steer the compaction passes.  This study was aimed at developing a measuring device for onsite density measurement.  The basis of the measuring device was a source of caesium radiation with an activity of    37 MBq and a sodium iodide scintillation detector.  The measuring device used the backscattering method.  The source and detector were located in a measuring wheel that was connected with the tractor via the rear three-point linkage.  During measuring passes on bunker silos both the density increase in the case of several crossings and the elastic recovery of the material could be seen clearly.  In connection with satellite-based position determination, the silo surface can be mapped according to density.  As a result of the random decay of the caesium, the error in density measurement was only ±4% at   600 kg m-3.   Keywords: silage compaction, bunker silo, silage density, radiometric measuring devic