Fizikalno i matematičko modeliranje fenomena procedure s dvofaznim tokom plin-prašak kroz pokretni “packed bed” u metalurškim pećima

Physical and chemical processes in shaft furnaces proceeds in counter – current system. Reacting gas carrying powders flows up in packed bed of descending metallurgical materials. In this system the problem of bed particles hanging up appears. That is why the author undertook the investigations of gas – powder flow in descending bed. Physical model with glass bed and glass powders was constructed. The experiments were carried out and the influences of gas velocity, type and size of powders, type and size of bed particles and powder concentration in gas were established. The conditions, in which bed hanging up appears were defined. Mathematical model of two phase (gas + powder) flow in moving bed was developed.Fizikalni i kemijski procesi u metalurškim pećima odvijaju se po protustrujnom sustavu. Reakcijski plin koji prenosi prašak utječe u “packed bed” opadajućeg metalurškog materijala. Kod ovog sustava javlja se problem zaostajanja čestica u sloju. Zbog toga je autor proveo istraživanje protoka plin-prašak u opadajućem sloju. Izrađen je fizički model sa staklemim slojem i staklenim praškom. Provedeni su eksperimenti i određeni su utjecaj brzine plina, tipa i veličine praška, tipa i veličine čestica sloja (bed particles) i koncentracije praška u plinu. Definirani su uvjeti u kojima se javlja zaostajanje u sloju. Razvijen je matematički model toka dvije faze (plin+prašak) u “moving bed”

Model investigations 3D of gas-powder two phase flow in descending packed bed in metallurgical shaft furnaces

This paper presents the second phase of model investigations of static pressure radial distribution conducted on 4 levels of bed height. During the phase the diameter of glass bed particles was increased, blast-furnace pellets were introduced as bed and iron powder was used as powder. Experiments were carried out with regard to gas velocity, bed and powder type and size of bed particles. The radial distribution of 3 fractions of powder accumulated in the bed – static powder, dynamic powder and total powder was calculated from experimentally obtained values of radial distribution of static powder. The influence analysis of the change of investigated bed and powder parameters on values of interaction forces between flow phases as well as on phenomena occurring in the system was conducted

Utilisation of noise level emitted by the electric arc furnace (EAF) for optimisation of the feeding process of slag foaming materials

The present paper reveals methodology of a research and the results of noise level measurements with respect to fluctuations of active power during EAF operation in one of the melt shops in Poland. In the current stage of experiment, the authors focused themselves on finding the optimum moment to start feeding of foaming material with the aim to obtain the most efficient slag foaming with the fastest coverage of electric arcs at the lowest losses of foaming material. Achieved results indicate that relation between the level of emitted noise and fluctuations of active power during melting can be utilised to define the moment to start feeding of slag foaming materials into the furnace

Utilisation of noise level emitted by the electric arc furnace (EAF) for optimisation of the feeding process of slag foaming materials

The present paper reveals methodology of a research and the results of noise level measurements with respect to fluctuations of active power during EAF operation in one of the melt shops in Poland. In the current stage of experiment, the authors focused themselves on finding the optimum moment to start feeding of foaming material with the aim to obtain the most efficient slag foaming with the fastest coverage of electric arcs at the lowest losses of foaming material. Achieved results indicate that relation between the level of emitted noise and fluctuations of active power during melting can be utilised to define the moment to start feeding of slag foaming materials into the furnace

Improvement of the process of feeding the slag-foaming material to the electric arc furnace (EAF), using of the sound

The research described, aimed to determine the value of the sound level (originating exclusively from the operating electric arc) at which the feeding of the slag foaming material to the Electric Arc Furnace (EAF) should start, in correlation with the stabilization of the furnace’s active power consumption level. For this purpose, the frequency band generated by the working electric arc was extracted from the entire spectrum of sound emitted by the furnace. Using sound analysis in 1/3 octave bands, the focus was on the band with a center frequency of 100 Hz. It was found that feeding the foaming material should start at a sound level of 103 dB

Industrial investigations of the liquid steel filtration

Hitherto existing investigations concerning the ceramic filter use in the steel making processes have given good results. The obtained results of filtration have proved that this method may be used as an effective and cheap way of steel filtration from non-metallic inclusions. Placing filters in the tundish is the best location considering the limitation of the possibility of secondary pollution of steel. Yet, the results presented in this paper, of an experiment prepared and carried out in the industrial environment, are the only positive results obtained, which are connected with so much quantities of liquid steel processed with use of the multi-hole ceramic filters

Photoelectrochemical properties of sol–gel obtained titanium oxide

The photoelectrochemical properties of a sol–gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350 °C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO2 electrode upon illumination by UV light in H2SO4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions

CI observations in the CQ Tau proto-planetary disk: evidence for a very low gas-to-dust ratio ?

Gas and dust dissipation processes of proto-planetary disks are hardly known. Transition disks between Class II (proto-planetary disks) and Class III (debris disks) remain difficult to detect. We investigate the carbon chemistry of the peculiar CQ Tau gas disk. It is likely a transition disk because it exhibits weak CO emission with a relatively strong millimeter continuum, indicating that the disk might be currently dissipating its gas content. We used APEX to observe the two CI lines at 492GHz and 809 GHz in the disk orbiting CQ Tau. We compare the observations to several chemical model predictions. We focus our study on the influence of the stellar UV radiation shape and gas-to-dust ratio. We did not detect the CI lines. However, our upper limits are deep enough to exclude high-CI models. The only available models compatible with our limits imply very low gas-to-dust ratio, of the order of a few, only. These observations strengthen the hypothesis that CQ Tau is likely a transition disk and suggest that gas disappears before dust.Comment: 5 pages, 5 figures, accepted for publication in A&

Pancreatic Cancer Malnutrition and Pancreatic Exocrine Insufficiency in the Course of Chemotherapy in Unresectable Pancreatic Cancer

Background: Malnutrition and cachexia are common in patients with advanced pancreatic ductal adenocarcinoma (PDAC) and have a significant influence on the tolerance and response to treatments. If timely identified, malnourished PDAC patients could be treated to increase their capacity to complete the planned treatments and, therefore, possibly, improve their efficacy. Aims: The aim of this study is to assess the impact of nutritional status, pancreatic exocrine insufficiency (PEI), and other clinical factors on patient outcomes in patients with advanced PDAC. Methods: PAncreatic Cancer MAlnutrition and Pancreatic Exocrine INsufficiency in the Course of Chemotherapy in Unresectable Pancreatic Cancer (PAC-MAIN) is an international multicenter prospective observational cohort study. The nutritional status will be determined by means of Mini-Nutritional Assessment score and laboratory blood tests. PEI will be defined by reduced fecal elastase levels. MAIN OUTCOME: adherence to planned chemotherapy in the first 12 weeks following the diagnosis, according to patients' baseline nutritional status and quantified and reported as "percent of standard chemotherapy dose delivered." SECONDARY OUTCOMES: rate of chemotherapy-related toxicity, progression-free survival, survival at 6 months, overall survival, quality of life, and the number of hospitalizations. ANALYSIS: chemotherapy dosing over the first 12 weeks of therapy (i.e., percent of chemotherapy received in the first 12 weeks, as defined above) will be compared between well-nourished and malnourished patients. SAMPLE SIZE: based on an expected percentage of chemotherapy delivered of 70% in well-nourished patients, with a type I error of 0.05 and a type II error of 0.20, a sample size of 93 patients per group will be required in case of a percentage difference of chemotherapy delivered of 20% between well-nourished and malnourished patients, 163 patients per group in case of a difference of 15% between the groups, and 356 patients per group in case of a 10% difference. Centers from Russia, Romania, Turkey, Spain, Serbia, and Italy will participate in the study upon Local Ethics Committee approval. Discussion: PAC-MAIN will provide insights into the role of malnutrition and PEI in the outcomes of PDAC. The study protocol was registered at clinicaltrials.gov as NCT04112836

“I’m Not Waving, I’m Drowning”: An Autoethnographical Exploration of Biographical Disruption and Reconstruction During Recovery From Prescribed Benzodiazepine Use

Benzodiazepines are group of drugs used mainly as sedatives, hypnotics, muscle relaxants, and anti-epileptics. Tapering off benzodiazepines is, for some users, a painful, traumatic, and protracted process. In this article, I use an autoethnographic approach, adopting the metaphor of water, to examine heuristically my experience of iatrogenic illness and recovery. I draw on personal journals and blog entries and former users’ narratives to consider the particular form of biographical disruption associated with benzodiazepines and the processes involved in identity reconstruction. I emphasize the role of the online community in providing benzodiazepine users such as myself with a co-cultural community through which to share a voice and make sense of our experiences. I explain how the success stories of former users provided me with the hope that I, the “medical victim,” could become the “victor” and in the process construct a new life and fresh identity