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Open access

Janusz Krawczyk and Bogdan Pawłowski

Abstract

Generally, the power and capacity of the armoured face conveyor (AFC) are determined by the motor size, pan width and chain size. It is well known that the dynamic behaviour of an AFC drive has a significant influence on tension in the AFC chain, and is therefore critical in determining the reliability of the chain and the entire AFC system. However, the chain long service life is also affected by tribological contact with the chain race plate of the AFC and with the coal. The main objective of this work was to determine the tribological properties of AFC twin chain race (top plate). Characterization of the twin chain race, made of the Hardox 450 abrasion resistant steel, included microstructural examination by light microscopy, hardness test, X-ray diffraction and examination of tribological properties. The studies were carried out on samples cut from top plate of the whitdrawn face conveyor twin chain race. It was found, that the Hardox450 steel has quite good wear resistance for such purpose as AFC twin chain race. It is possible to use more wear resistant material than Hardox 450 steel but it would cause premature wear of the AFC chain.

Open access

Janusz Pusz, Wojciech Zapała and Bogdan Papciak

Investigations of selected properties of pharmacologically active compounds by chromatographic and potentiometric methods on the chrysin example

The RP-TLC method was used to determine the dissociation constant of chrysin (5,7-dihydroxyflavone) in methanol-aqueous (1:1 v/v) solutions. In this method the pK value was quantified on the basis of retention data and a retention model. The accuracy of determining the model parameters was analysed using the following statistical criteria: the sum of the squared differences between the experimental and theoretical data, approximation of standard deviation, and the Fisher test. Besides, in this work the potentiometric method was used. Investigations were carried out at ionic strength I=0.1 at T= 298 K. The dissociation constant were determined using the Rossotti method as well as the numerical method based on the procedures of non-linear curve fitting using Microsoft Excel Solver and the user-defined function. It has been found that the differences in the evaluated pK values were relatively small and did not exceed 1.2%.

Open access

Janusz Wojdalski, Bogdan Dróżdż, Janusz Piechocki, Marek Gaworski, Zygmunt Zander and Jan Marjanowski

This paper analyzes the correlations between selected technical, process and production factors, equipment profiles and water consumption statistics in four types of dairy plants. Dairy plants were surveyed both individually and in groups. Water consumption was most highly correlated (r > 0.868) with equipment profiles. The highest water consumption was observed in dairy plants operating milk powder departments. In those plants, organization and production factors could significantly reduce water consumption levels because in addition to milk powder, those plants also supplied eight other products. The indicators of water consumption per unit of the final product were correlated (at 0.820 > | r | > 0.663) with equipment profiles, the degree of process automation and employment. Variations in water consumption per unit of the final product were best explained in small plants supplying several products. The presented equations can be used to optimize water demand of various types of equipment and to determine the correlations with energy consumption for wastewater treatment. Our results can contribute to the development of water consumption models in dairy plants and the implementation of clean production standards.

Open access

Justyna Bogdan, Ahmed Elsaftawy, Janusz Kaczmarzyk and Jerzy Jabłecki

Epidemiological Characteristic of Acute Pancreatitis in Trzebnica District

Acute pancreatitis is one of the most common surgical disease, and thus cause of hospitalization. Incidence and etiology of this condition demonstrates large regional differences. This situation is a substantial financial burden forhospital district, and changes in organization structure and funding medical service should be taken under consideration.

The aim of the study was to record the epidemiology with etiology, diagnosis and treatment of acute pancreatitis in large district (77 000 inhabitants).

Material and methods. A meta-analysis study of all 298 patients admitted to Hospital St Hedwig in Trzebnica, in the six-year period from 2005 to 2010, with acute pancreatitis was performed.

Results. Acute pancreatitis was diagnosed in 298 patients in the six - year period, giving an estimated incidence of 64.4 per 100 000. Among the group of 441 admissions for acute pancreatitis in 298 patients was confirmed. Severe acute pancreatitis developed in 22.5% (67/298) of patients, more often in males 56/208 (27%) than in females 11/90 (12%). Gallstones were found as an etiological factor in 27% (80/298), and alcohol intake in 49% of patients. 211/298 (70%) patients had only one attack, whereas 29% (87/298) were readmitted with 230 relapses. The risk of recurrent pancreatitis was 48% in alcohol induced and 6,25% in gallstone induced pancreatitis. 53/298 patients (17%) were operated, ERCP procedures were performed in 24.

Performed operations: necrosectomy in 25/53 (47%), elective cholecystectomy in 16/53 (30%), open drainage of abdominal abscess in 5/53 (9%), open drainage of cysts in 5/53 (9%), Jurasz's operation in 2/53 (3%). Majority surgical treatment was carried out in 68% cases with severe acute pancreatitis. Mortality due to acute pancreatitis was 3% (10/298); 15% in severe pancreatitis.

Conclusions. 1. Acute pancreatitis continues to be an important clinical problem. 2. Severe, necrotic acute pancreatitis is associated with high mortality rates. 3. The ethanol-intake-related episodes of acute pancreatitits are much more prevalent than the gall-stone-related ones. 4. After the exclusion of ethanol- and gall-stones-related etiologies, the subsequent diagnostic process should aim at excluding neoplastic process of the head of pancreas.

Open access

Janusz Gołdasz and Bogdan Sapiński

Abstract

The study deals with the pinch mode of magnetorheological (MR) fluids’ operation and its application in MR valves. By applying the principle in MR valves a highly non-uniform magnetic field can be generated in flow channels in such a way to solidify the portion of the material that is the nearest to the flow channel’s walls. This is in contrary to well-known MR flow mode valves. The authors investigate a basic pinch mode valve in several fundamental configurations, and then examine their magnetic circuits through magnetostatic finite-element (FE) analysis. Flux density contour maps are revealed and basic performance figures calculated and analysed. The FE analysis results yield confidence in that the performance of MR pinch mode devices can be effectively controlled through electromagnetic means.

Open access

Adam Polak, Grzegorz Głomb, Tomasz Guszkowski, Ireneusz Jabłoński, Bogdan Kasprzak, Janusz Pękala, Andrzej Stępień, Zbigniew Świerczyński and Janusz Mroczka

Telemedical System "Pulmotel-2010" for Monitoring Patients with Chronic Pulmonary Diseases

Telemedicine is one of the most innovative and promising applications of technology in contemporary medicine. Telemedical systems, a sort of distributed measurement systems, are used for continuous or periodic monitoring of human vital signals in the environment of living. This approach has several advantages in comparison to traditional medical care: e.g. patients experience fewer hospitalizations, emergency room visits, lost time from work, the costs of treatment are reduced, and the quality of life is improved. Currently, chronic respiratory diseases comprise one of the most serious public health problems. Simultaneously patients suffering from these diseases are well suitable for home monitoring. This paper describes the design and technical realization of a telemedical system that has been developed as a platform suitable for monitoring patients with chronic pulmonary diseases and fitted to Polish conditions. The paper focuses on the system's architecture, included medical tests, adopted hardware and software, and preliminary internal evaluation. The performed tests demonstrated good overall performance of the system. At present further work goes on to put it into practice.

Open access

Janusz Gołdasz and Bogdan Sapiński

Abstract

The so-called squeeze flow involves a magnetorheological (MR) fluid sandwiched between two planar surfaces setting up a flow channel. The height of the channel varies according to a prescribed displacement or force profile. When exposed to a magnetic field of sufficient strength MR fluids develop a yield stress. In squeeze-mode devices the yield stress varies with both the magnetic field magnitude and the channel height. In this paper an unsteady flow model of an MR fluid in squeeze mode is proposed. The model is developed in Ansys Fluent R16. The MR material flow model is based on the apparent viscosity approach. In order to investigate the material's behaviour the authors prepared a model of an idealized squeeze-mode damper in which the fluid flow is enforced by varying the height of the channel. Using mesh animation, the model plate is excited, and as the mesh moves, the fluid is squeezed out of the gap. In the simulations the model is subjected to a range of displacement inputs of frequencies from 10 to 20 Hz, and local yield stress levels up to 30 kPa. The results are presented in the form of time histories of the normal force on the squeezing plate and loops of force vs. displacement (velocity).

Open access

Bogdan Pawłowski, Janusz Krawczyk, Piotr Bała, Grzegorz Cios and Tomasz Tokarski

Abstract

This paper describe the investigation of a water-expanded rock bolts failed during pressure test (inner water pressure of 330 bar). A main objective of this work was to determine the cracks nucleation and propagation mechanism. It was found that the rock bolts failure was promoted by presence of non-metallic inclusions (mainly long sulphide inclusions) but the primary cause of cracking is strain ageing of steel. Suggestions for improving the behaviour of steel used for water-expanded rock belts by the modification of its chemical composition are proposed finally.

Open access

Piotr M. Kurzydło, Antoni T. Pędziwiatr, Bogdan F. Bogacz, Janusz Przewoźnik and Dariusz Oleszak

Abstract

The spin reorientation process in the Tm2-xHoxFe14B series of compounds was studied using 57Fe Mössbauer spectroscopy over the temperature range 5.2-320 K with a focus on the analysis of conical spin arrangement. Each compound was studied by precise Mössbauer scanning in the vicinity of the transition and during the transition. By applying computer simulations based on the simplified Yamada-Kato model, as well as on some literature data for R2Fe14B (R = Tm, Ho) compounds, the above series was selected for studies as it contains compounds with different spin arrangements (axial, planar, conical). It was a crucial requirement for obtaining unambiguous angular dependences when applying a simultaneous fitting procedure of Mössbauer spectra. Such an extended procedure was applied which allowed the temperature dependence of the angle describing the position of the magnetization vector to be obtained. The results were compared with those from theoretical simulations. The spin arrangement diagram was constructed. A conical spin arrangement was confirmed over a wide temperature range.

Open access

Piotr M. Kurzydło, Bogdan F. Bogacz, Antoni T. Pędziwiatr, Dariusz Oleszak and Janusz Przewoźnik

Abstract

The materials studied were polycrystalline compounds Er2− xTbxFe14B (x = 0.1, 0.2, 0.3, 0.4) which crystallize in a tetragonal lattice and display a variety of spin arrangements. The compounds have been measured with 57Fe Mössbauer spectroscopy over the temperature range 80–320 K in order to investigate the spin reorientation processes. Each compound was studied in a wide temperature range, with precise Mössbauer scanning in the vicinity of the transition. The set of spectra obtained for a given compound was analyzed using simultaneous fitting procedure to investigate the influence of the transition on the shape of the spectra. The fitting program was specified to analyze the transition according to the ‘two state model’: spins flip abruptly from initial angle to final arrangement (90° angle). Obtained results suggest that spin reorientation process cannot be described using only the mentioned above model. Additional computer simulations based on the Yamada–Kato model were conducted to determine temperature range and the type of spin alignments in the vicinity of the transition. These theoretical results supported by spectra analysis suggest the existence of intermediate (canted) spin arrangements in the studied compounds. The spin arrangement diagram was constructed.