Myśl i polityka: księga pamiątkowa dedykowana profesorowi Jackowi Marii Majchrowskiemu T. 3

Publikacja jubileuszowa z okazji 40-lecia pracy naukowej profesora Jacka Majchrowskieg

Control supply system and measurement properties of spindle with angular contact bearings using LabVIEW

The paper presents a research position with the spindle-speed. It is used in the PhD thesis, the aim of which is to develop an active bearing case. This case is intended to provide the opportunity to actively change the preload of the spindle of ball angular contact bearings. The article describes the construction of the test and the parameters of both spindle and measurement systems. It shows the hardware configuration used for the initial measurements. These measurements will allow to determine the operating parameters of the spindle so that setting a real relationship changes the preload of the spindle for changing working conditions. For data acquisition and control software environment LabVIEW was used, its general philosophy is presented in the work. The authors also present the application created in this program which allows for simultaneous control of spindle speed and monitoring of selected parameters of its work

Modelled phenomenon of burr formation during machining

A model of burr formation on the edge of the workpiece in the course of machining is presented. The material being machined, the cutting tool and the machining parameters were modelled. Material properties and type of its deformations have been modelled with the use of a constitutive Johnson - Cook model. Material damage initiation criteria and associated damage evolution have been modelled with the use of the ductile damage and the Johnson- Cook damage initiation criterion. Simulations of the machining process for different depths of cut were carried out. The real burr formation presented by Hashimura was compared with the modelled one. The influence of the cutting parameters on the form and size of burr has been analysed. Calculations have been realised utilising finite element method with the use of nonlinear analysis in ABAQUS/Explicit environment. Based on simulation results, the assessment of the form and size of burr has been made. Burr height was used to evaluate its size, which was derived according to ISO 13715 standard. The goal was to obtain a model that reliably reflects the behaviour of material during machining, with particular emphasis on supporting the creation of cutting phenomenon of burr formation. The results of simulation and computational analysis confirmed that the model reflects the real behaviour of the material

Numerical model of fricional damper for glas – making robot lance

The need to design a friction damper for glass-making robots arose because of the excessive vibrations, which occur in the course of their work. The robots are commonly used in the manufacture of glassware. The vibrations adversely affect the work of ball gatherers, which results in a large number of defects in the finished glass products. As a result of the vibrations molten glass may become unevenly distributed on the ball's surface and as the material flows down the ball into the mould the thermal conditions of its solidification may change. It is proposed to damp the vibrations by means of a prototype friction damper mounted directly on the ball gatherer lance. The glass-making robot lance with the friction damper was modelled. The vibrations of the glass-making robot lance tip under static load and impact excitation were measured during simulations. Also the relative displacements of the damper rings in the course of the excitations were measured. Moreover, the dependence between the preload force and the system's damping decrement was determined. The main aim was to select proper operating parameters for the proposed structure in order to obtain maximum system damping

Comparison of Methods for Adjusting and Controlling the Preload of Angular-Contact Bearings

The effect of preload on the operating conditions of angular-contact bearings is described. The interdependences occurring during mutual displacements of bearing rings at different bearing contact angles are discussed. The criteria of the classification into low-speed and high-speed angular-contact bearings are presented. Selected methods of preloading angular-contact bearings are compared and discussed. Their advantages and disadvantages with regard to the active control and adjustment of the bearing system during its operation are presented. The structure of a developed test stand with a spindle assembly is described. Preliminary measurements of the behaviour of the spindle assembly during operation are reported. Conclusions are drawn and the direction for further research is indicated

Finite Element Modelling of burr formation in metal cutting

The paper presents a two-dimensional FEM model of burr formation in metal cutting. Abaqus/Explicit software was used for the build of the model. The workpiece geometry, the tool and the cutting parameters were modelled. Physical properties and the method of deformation and fracture of the workpiece material is described using Johnson Cook's constitutive law and the ductile damage criterion. The simulation of the edge formation process during orthogonal cutting was carried out for different depths of cut and cutting speeds. The results of these simulations allowed the verification of the FEM model. The components of the resultant cutting force measured during the actual cutting process with the values of these forces determined based on FEM simulation of this process were compared. The geometry of burrs formed during the actual and simulated the edge forming process was assessed. The analysis showed that the FEM model built enabled a correct prediction of the shape of the workpiece edge and the estimation of geometric features of the edge

Bacterial etiology of community-acquired pneumonia in immunocompetent hospitalized patients and appropriateness of empirical treatment recommendations: an international point-prevalence study

An accurate knowledge of the epidemiology of community-acquired pneumonia (CAP) is key for selecting appropriate antimicrobial treatments. Very few etiological studies assessed the appropriateness of empiric guideline recommendations at a multinational level. This study aims at the following: (i) describing the bacterial etiologic distribution of CAP and (ii) assessing the appropriateness of the empirical treatment recommendations by clinical practice guidelines (CPGs) for CAP in light of the bacterial pathogens diagnosed as causative agents of CAP. Secondary analysis of the GLIMP, a point-prevalence international study which enrolled adults hospitalized with CAP in 2015. The analysis was limited to immunocompetent patients tested for bacterial CAP agents within 24 h of admission. The CAP CPGs evaluated included the following: the 2007 and 2019 American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA), the European Respiratory Society (ERS), and selected country-specific CPGs. Among 2564 patients enrolled, 35.3% had an identifiable pathogen. Streptococcus pneumoniae (8.2%) was the most frequently identified pathogen, followed by Pseudomonas aeruginosa (4.1%) and Klebsiella pneumoniae (3.4%). CPGs appropriately recommend covering more than 90% of all the potential pathogens causing CAP, with the exception of patients enrolled from Germany, Pakistan, and Croatia. The 2019 ATS/IDSA CPGs appropriately recommend covering 93.6% of the cases compared with 90.3% of the ERS CPGs (p < 0.01). S. pneumoniae remains the most common pathogen in patients hospitalized with CAP. Multinational CPG recommendations for patients with CAP seem to appropriately cover the most common pathogens and should be strongly encouraged for the management of CAP patients.info:eu-repo/semantics/publishedVersio

Prevalence and Etiology of Community-acquired Pneumonia in Immunocompromised Patients

BACKGROUND: The correct management of immunocompromised patients with pneumonia is debated. We evaluated the prevalence, risk factors, and characteristics of immunocompromised patients coming from the community with pneumonia. METHODS: We conducted a secondary analysis of an international, multicenter study enrolling adult patients coming from the community with pneumonia and hospitalized in 222 hospitals in 54 countries worldwide. Risk factors for immunocompromise included AIDS, aplastic anemia, asplenia, hematological cancer, chemotherapy, neutropenia, biological drug use, lung transplantation, chronic steroid use, and solid tumor. RESULTS: At least 1 risk factor for immunocompromise was recorded in 18% of the 3702 patients enrolled. The prevalences of risk factors significantly differed across continents and countries, with chronic steroid use (45%), hematological cancer (25%), and chemotherapy (22%) the most common. Among immunocompromised patients, community-acquired pneumonia (CAP) pathogens were the most frequently identified, and prevalences did not differ from those in immunocompetent patients. Risk factors for immunocompromise were independently associated with neither Pseudomonas aeruginosa nor non-community-acquired bacteria. Specific risk factors were independently associated with fungal infections (odds ratio for AIDS and hematological cancer, 15.10 and 4.65, respectively; both P = .001), mycobacterial infections (AIDS; P = .006), and viral infections other than influenza (hematological cancer, 5.49; P &lt; .001). CONCLUSIONS: Our findings could be considered by clinicians in prescribing empiric antibiotic therapy for CAP in immunocompromised patients. Patients with AIDS and hematological cancer admitted with CAP may have higher prevalences of fungi, mycobacteria, and noninfluenza viruses

Prevalence and risk factors for Enterobacteriaceae in patients hospitalized with community-acquired pneumonia

Background and objective Enterobacteriaceae (EB) spp. family is known to include potentially multidrug-resistant (MDR) microorganisms, and remains as an important cause of community-acquired pneumonia (CAP) associated with high mortality. The aim of this study was to determine the prevalence and specific risk factors associated with EB and MDR-EB in a cohort of hospitalized adults with CAP. Methods We performed a multinational, point-prevalence study of adult patients hospitalized with CAP. MDR-EB was defined when >= 3 antimicrobial classes were identified as non-susceptible. Risk factors assessment was also performed for patients with EB and MDR-EB infection. Results Of the 3193 patients enrolled with CAP, 197 (6%) had a positive culture with EB. Fifty-one percent (n = 100) of EB were resistant to at least one antibiotic and 19% (n = 38) had MDR-EB. The most commonly EB identified were Klebsiella pneumoniae (n = 111, 56%) and Escherichia coli (n = 56, 28%). The risk factors that were independently associated with EB CAP were male gender, severe CAP, underweight (body mass index (BMI) < 18.5) and prior extended-spectrum beta-lactamase (ESBL) infection. Additionally, prior ESBL infection, being underweight, cardiovascular diseases and hospitalization in the last 12 months were independently associated with MDR-EB CAP. Conclusion This study of adults hospitalized with CAP found a prevalence of EB of 6% and MDR-EB of 1.2%, respectively. The presence of specific risk factors, such as prior ESBL infection and being underweight, should raise the clinical suspicion for EB and MDR-EB in patients hospitalized with CAP

Microbiological testing of adults hospitalised with community-acquired pneumonia: an international study

This study aimed to describe real-life microbiological testing of adults hospitalised with community-acquired pneumonia (CAP) and to assess concordance with the 2007 Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) and 2011 European Respiratory Society (ERS) CAP guidelines. This was a cohort study based on the Global Initiative for Methicillin-resistant Staphylococcus aureus Pneumonia (GLIMP) database, which contains point-prevalence data on adults hospitalised with CAP across 54 countries during 2015. In total, 3702 patients were included. Testing was performed in 3217 patients, and included blood culture (71.1%), sputum culture (61.8%), Legionella urinary antigen test (30.1%), pneumococcal urinary antigen test (30.0%), viral testing (14.9%), acute-phase serology (8.8%), bronchoalveolar lavage culture (8.4%) and pleural fluid culture (3.2%). A pathogen was detected in 1173 (36.5%) patients. Testing attitudes varied significantly according to geography and disease severity. Testing was concordant with IDSA/ATS and ERS guidelines in 16.7% and 23.9% of patients, respectively. IDSA/ATS concordance was higher in Europe than in North America (21.5% versus 9.8%; p<0.01), while ERS concordance was higher in North America than in Europe (33.5% versus 19.5%; p<0.01). Testing practices of adults hospitalised with CAP varied significantly by geography and disease severity. There was a wide discordance between real-life testing practices and IDSA/ATS/ERS guideline recommendations