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[en] The aim of present research was to measure and analyze the dynamic changes of internal pressure in shrinking vs. non-shrinking materials during convective drying for the use as a possible process control method. Drying experiments were carried out on wet and fired clay at 50°C and 60°C. In addition, the shrinkage curve was investigated. Experimental measurements show the existence of 4 stages of the process. The comparison of the results for wet and fired clay shows differences in pressure trends. During drying the internal pressure changes from underpressure to overpressure at the level of 3÷5kPa, what correlates well with transition from the first to the second drying period. (Author)
[en] Electrostatic collection technique is widely used in various radon monitors. The mechanism of this kind of radon monitor is that the positive Po particles, produced by decay of radon, can be collected on the surface of detector in electric field. Collection efficiency, therefore, could be affected by air humidity. Calibration under different humidity conditions or test of humidity response is necessary consequently. In this study, a humidity control technique based on Nafion membrane tube (NMT) is developed. Under a consistent flowrate with a certain stable level of radon concentration and humidity of main-path inlet, the humidity of outlet sample gas from the main-path can be adjusted and stably controlled at a certain level by changing side-path's flowrates of NMT. By adjusting main and side-path flowrate, RH of outlet gas of the main-path can be controlled from 5.3 to 80.0%. Theoretical study were also performed. Based on this, humidity influence calibration of an electrostatic radon monitor was performed, and a relationship between the sensitivity of the radon monitor and relative humidity was obtained. (authors)
[en] Complete text of publication follows. Riso B3 dosimeters were laminated by standard office lamination technique in order to protect them against environmental humidity influence. The properties of this modified dosimeter were determined and compared with the properties of the un-modified thin-film dosimeter. Irradiations were carried out at a 10 MeV electron accelerator and at a cobalt-60 gamma cell. Optimum post irradiation heating conditions were determined. It was possible to irradiate the dosimeter immersed in water, but the lamination did not provide an effective humidity barrier, and some influence of different humidities during irradiation on the response of the laminated dosimeter was found. The response of the laminated dosimeter was found to be as stable in time after irradiation as the un-modified dosimeter
[en] The safe and accurate delivery of the prescribed absorbed dose is the central function of the dose monitoring and beam stabilization system in a medical linear accelerator. The absorbed dose delivered to the patient during radiotherapy is often monitored by a transmission ionization chamber. Therefore it is of utmost importance that the chamber behaves correctly. We have noticed that the sensitivity of an unsealed chamber in a Philips SL linear accelerator changes significantly, especially during and after the summer season. The reason for this is probably a corrosion effect of the conductive plates in the chamber due to the increased relative humidity during hot periods. We have found that the responses of the different ion chamber plates change with variations in air humidity and that they do not return to their original values when the air humidity is returned to ambient conditions. (author)
[en] Concerning with applied nitrogen fertilizer, the uptake as well as loss of nitrogen is mainly related to soil water content. The effects of soil water condition in wheat field on the uptake, leach and loss of nitrogen fertilizer were studied using 15N tracing technique. The results showed that within certain range of soil water supply, from 180 to 360 mm of available water storage, the loss of nitrogen was in direct proportion to the amount of fertilizer application and the nitrogen use efficiency decreased with the increase of nitrogen application. In other words, the nitrogen use efficiency descended with the nitrogen application increased in an order of 75 kgN/ha, 150 kgN/ha, 225 kgN/ha. One interesting result was that the nitrogen use efficiencies ranged from 17.0% to 30.5% for the treatments receiving the same application rate of 75 kgN/ha
[en] Convective drying is a common process for the treatment of particulate solids also operated in continuous mode. Continuous operation is characterised by operation in steady-state with constant product throughput and constant product quality. Due to external influences, i.e. seasonal or local variations in the properties of the initial wet material, deviations in the product quality can result, for example over- or under-drying, or on-set of unwanted reaction. In this contribution a new feedback control concept is developed that is robust with respect to variations and uncertainties in the drying kinetics of the material and can reject and attenuate process disturbances. (Author)
[en] Recording high quality biosignals by dry textile electrodes is a common challenge in medical health monitoring garments. The aim of this study was to improve skin–electrode interface and enhance the quality of recorded electrocardiography (ECG) signals by modification of textile electrodes embedded in WearItMed smart garment. The garment has been developed for long-term health monitoring in patients suffering from epilepsy and Parkinson’s disease. A skin-friendly electro-conductive elastic paste was formulated to coat and modify the surface of the knitted textile electrodes. The modifications improved the surface characteristics of the electrodes by promoting a more effective contact area between skin and electrode owing to a more even surface, fewer pores, greater surface stability against touch, and introduction of humidity barrier properties. The modifications decreased the skin–electrode contact impedance, and consequently improved the recorded ECG signals obviously when low pressure was applied to the electrodes, therefore contributed to greater patient comfort. The created contact surface allowed the natural humidity of the skin/sweat to ease the signal transfer between the electrode and the body, while introducing a shorter settling time and retaining moisture over a longer time. Microscopic images, ECG signal measurements, electrode–skin contact impedance at different pressures and times, and water absorbency were measured and reported.
[en] Accurately calibrating a neutron probe for the field measurement of soil water content is not a simple task. The most straightforward calibration technique is done in the field by determining the volumetric soil water content of soil cores taken around the access tube and relating it to the instrument reading. Although the sampling procedure is time-consuming and sometimes arduous, it is probably the most accurate method currently in use. Plastic cylinders of different outside diameters have been found to be valuable intermediate standards for transferring the field calibration from one neutron probe to another when the detector type, source strength, and geometry are similar. This new technique will greatly facilitate the calibration of any number of neutron probes in many different soils. (author)
[en] In spite of extensive investigation and applications, influence of oxygen (O), and humidity on polyaniline (PANI) behaviour is not well understood. For this reason we have performed semi-empirical quantum mechanics, and ab-initio calculations of the pernigraniline base (PNB) PANI oligomers, of various lengths, before and after approach of H2O, O2 , and hydroxyl (OH −) group, and attachment of OH − and O to various molecular positions. Structure, charge and electrostatic potential distribution, relevant energies and enthalpies, infrared and electronic spectra of the PNB tetramer equilibrium conformation, and their changes induced by specific OH − , and O attachments are determined. These results provide identification of the most probable positions for O2 and H2O approach to PNB_PANI, enthalpies of OH − and O attachments to them, changes of molecular properties induced by the attachments, and infrared and electronic modes that are most suitable for the attachments detection. The results are compared to the existing experimental data, and the results of similar calculations, and implications for the PNB_PANI applications are notified. © 2019 Elsevier B.V.
[en] Multiple cropping is a centuries-old technique of intensive farming that has persisted in many areas of the world as a method of maximizing land productivity per unit area per season. One of the main advantages of multiple cropping is the better exploitation of soil resources through the uptake of nutrients and water from different soil depths and at different rates and times depending on the growth cycles and root system distribution of the crops under consideration. The evaluation of water management practices for crop systems have to be based on following moisture changes in soil profiles while taking into consideration soil physical properties and the prevailing weather conditions. This requires the performance of very large numbers of soil moisture determinations which are very tedious, expensive and time consuming. The various types of portable radiation equipment now commercially available make intensive soil moisture studies possible. The paper discusses the principles involved as well as the advantages and limitations of using different types of radiation equipment for measuring soil moisture contents. (author)