Analyses and solutions on technical and economical aspects of rapid prototyping technology

Ovaj članak se bavi osnovnim karakteristikama i problemima u području tehnologije brze izrade prototipa, korištenjem 3D printanja. Ta tehnologija spada u progresivne metode stvaranja modela na temelju geometrije dobivene u CAD okruženju, s mogućnosti primjene u različitim područjima. Poglavlja su usmjerena na optimizaciju procesa 3D printanja. Tu je također algoritam koji prikazuje izbor optimalnih postavki. Upotreba algoritma je objašnjena na primjeru printanja s UPrint uređajem i Catalyst softverom, sustavom stvorenim za uprabu tehnologije modeliranja taložnim srašćivanjem. Postoje izlazi u obliku grafova i tablica s puno informacija koje izravno prikazuju ekonomsku isplativost printanja. Zaključak donosi ideje o mogućem daljnjem napretku u ovom području, koje će uključivati bazu podataka s pohranjenim informacijama o prethodnim rezultatima.This article deals with basic characteristics and problems in the area of technology of Rapid Prototyping using layered manufacturing technology. It belongs to progressive methods of model creation based on geometry obtained from CAD environment with application possibilities in different industrial spheres. Chapters are focused on optimization of Rapid Prototyping preparation process. There is also an algorithm that leads to the selection of suitable settings. Utilization of the algorithm is explained on a case of printing with the use of UPrint device and Catalyst software, a system created for the utilization of Fused Deposition Modelling technology. There are outputs in the form of graphs and tables accumulating information directly affecting economical aspects of printing. Conclusion brings ideas on possible further progress in this area that would include a solution for the generation of database with stored information about previous printing results

Application of FDM rapid prototyping technology in experimental gearbox development process

Ovaj rad u svom teorijskom dijelu prikazuje osnovne i napredne metode tehnologije brze izrade prototipa s posebnim naglaskom na modeliranje taloženjem (FDM), postupkom koji su koristili autori s Fakulteta proizvodnih tehnologija Tehničkog sveučilišta u Košicama sa sjedištem u Prešovu (Slovačka). Opisan je princip FDM postupka brze izrade prototipa i materijali koji se koriste za izradu modela i proizvoda s tim postupkom. Praktični dio ovog rada opisuje proces razvoja eksperimentalne mjenjačke kutije od 3D modeliranja pojedinih dijelova, preko realizacije montaže mjenjačke kutije, do primjene FDM postupka za proizvodnju dijelova mjenjačke kutije i konačnu montažu proizvoda.This paper in its theoretical part presents basic and advanced methods of Rapid Prototyping (RP) technology with a special focus on Fused Deposition Modelling (FDM) method used by authors on Faculty of Manufacturing Technologies of Technical University of Košice with a seat in Prešov (Slovakia). Principles of FDM technology and materials used for production of models and products are described. Practical part of the paper describes development process of experimental gearbox from 3D modelling of particular parts, through the realization of gearbox assembly, to application of FDM technology for production of gearbox parts and final assembly of the product

Possibility of quick check on suitability of milling strategy

Područje računalne potpore u proizvodnji u području strojne obrade još uvijek pruža prostor za poboljšanja u pitanjima odabira odgovarajuće proizvodne strategije tijekom stvaranja NC sekvenci. Rad analizira trenutnu situaciju rješenja za strategiju glodanja i važnosti odabira odgovarajuće strategije sa stajališta nekoliko parametara. Također donosi podatke o novoj softverskoj aplikaciji koja predstavlja alat za računalnu pomoć pri odabiru strategije glodanja na temelju kriterija potrebnog vremena za glodanje. Softver se opisuje sa aspekta programiranja i funkcionalnosti, te daje rezultate ostvarenih eksperimenata. Također se spominju mogućnosti daljnjeg razvoja aplikacije.The area of computer aided manufacturing in the field of chip machining still provides space for improvements in matters of selection of a suitable manufacturing strategy during creation of NC sequences. The paper analyzes current situation in solutions for milling strategies and importance of the selection of a suitable strategy from the viewpoint of several parameters. It also provides information about a newly created software application that presents the tool of computer aid to a milling strategy selection based on the criterion of necessary milling time. It describes functional and programming aspects of the program and offers the results obtained from the realized experiments. It also mentions the possibilities for further development of the application

Use of alternative scanning devices for creation of 3D models of machine parts

Snimanje 3D informacija bilo koje površine i danas je još uvijek veliki izazov. Neke komercijalne tehnike i tehnologije snimanja u uporabi su nekoliko godina, ali je potreban hardver i softver koji je još uvijek preskup za korisnike. Ovaj članak daje nekoliko jeftinijijih alternativnih postupaka snimanja površine, na temelju "open source" elemenata za komercijalnu uporabu beskontaktnih 3D skenera i dokazuje da su dobiveni podaci pogodni ne samo za hobi prostornu digitalizaciju, nego i za uporabu u industriji. U dijelu rada ukratko je opisan proces digitalizacije s nekoliko freeware i shareware programa.Capturing of 3D information about any kind of surface is currently a big challenge. A few proven commercial techniques and technologies are in use for a couple of years, but needed hardware and software are still too expensive for ordinary users of PC. This article provides a few cheaper alternatives based on open source elements to commercial non-contact 3D scanners and proves that the obtained data are suitable not only for hobby home spatial digitization but also for requisites in the industry. In various parts of the contribution there is a brief description of digitization process with mentioned freeware and shareware applications

Use of alternative scanning devices for creation of 3D models of machine parts

Snimanje 3D informacija bilo koje površine i danas je još uvijek veliki izazov. Neke komercijalne tehnike i tehnologije snimanja u uporabi su nekoliko godina, ali je potreban hardver i softver koji je još uvijek preskup za korisnike. Ovaj članak daje nekoliko jeftinijijih alternativnih postupaka snimanja površine, na temelju "open source" elemenata za komercijalnu uporabu beskontaktnih 3D skenera i dokazuje da su dobiveni podaci pogodni ne samo za hobi prostornu digitalizaciju, nego i za uporabu u industriji. U dijelu rada ukratko je opisan proces digitalizacije s nekoliko freeware i shareware programa.Capturing of 3D information about any kind of surface is currently a big challenge. A few proven commercial techniques and technologies are in use for a couple of years, but needed hardware and software are still too expensive for ordinary users of PC. This article provides a few cheaper alternatives based on open source elements to commercial non-contact 3D scanners and proves that the obtained data are suitable not only for hobby home spatial digitization but also for requisites in the industry. In various parts of the contribution there is a brief description of digitization process with mentioned freeware and shareware applications

Molecular Epidemiology and Evolutionary Trajectory of Emerging Echovirus 30, Europe

In 2018, an upsurge in echovirus 30 (E30) infections was reported in Europe. We conducted a large-scale epidemiologic and evolutionary study of 1,329 E30 strains collected in 22 countries in Europe during 2016-2018. Most E30 cases affected persons 0-4 years of age (29%) and 25-34 years of age (27%). Sequences were divided into 6 genetic clades (G1-G6). Most (53%) sequences belonged to G1, followed by G6 (23%), G2 (17%), G4 (4%), G3 (0.3%), and G5 (0.2%). Each clade encompassed unique individual recombinant forms; G1 and G4 displayed >= 2 unique recombinant forms. Rapid turnover of new clades and recombinant forms occurred over time. Clades G1 and G6 dominated in 2018, suggesting the E30 upsurge was caused by emergence of 2 distinct clades circulating in Europe. Investigation into the mechanisms behind the rapid turnover of E30 is crucial for clarifying the epidemiology and evolution of these enterovirus infections.Peer reviewe

Trends in invasive bacterial diseases during the first 2 years of the COVID-19 pandemic: analyses of prospective surveillance data from 30 countries and territories in the IRIS Consortium.

BACKGROUND The Invasive Respiratory Infection Surveillance (IRIS) Consortium was established to assess the impact of the COVID-19 pandemic on invasive diseases caused by Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Streptococcus agalactiae. We aimed to analyse the incidence and distribution of these diseases during the first 2 years of the COVID-19 pandemic compared to the 2 years preceding the pandemic. METHODS For this prospective analysis, laboratories in 30 countries and territories representing five continents submitted surveillance data from Jan 1, 2018, to Jan 2, 2022, to private projects within databases in PubMLST. The impact of COVID-19 containment measures on the overall number of cases was analysed, and changes in disease distributions by patient age and serotype or group were examined. Interrupted time-series analyses were done to quantify the impact of pandemic response measures and their relaxation on disease rates, and autoregressive integrated moving average models were used to estimate effect sizes and forecast counterfactual trends by hemisphere. FINDINGS Overall, 116 841 cases were analysed: 76 481 in 2018-19, before the pandemic, and 40 360 in 2020-21, during the pandemic. During the pandemic there was a significant reduction in the risk of disease caused by S pneumoniae (risk ratio 0·47; 95% CI 0·40-0·55), H influenzae (0·51; 0·40-0·66) and N meningitidis (0·26; 0·21-0·31), while no significant changes were observed for S agalactiae (1·02; 0·75-1·40), which is not transmitted via the respiratory route. No major changes in the distribution of cases were observed when stratified by patient age or serotype or group. An estimated 36 289 (95% prediction interval 17 145-55 434) cases of invasive bacterial disease were averted during the first 2 years of the pandemic among IRIS-participating countries and territories. INTERPRETATION COVID-19 containment measures were associated with a sustained decrease in the incidence of invasive disease caused by S pneumoniae, H influenzae, and N meningitidis during the first 2 years of the pandemic, but cases began to increase in some countries towards the end of 2021 as pandemic restrictions were lifted. These IRIS data provide a better understanding of microbial transmission, will inform vaccine development and implementation, and can contribute to health-care service planning and provision of policies. FUNDING Wellcome Trust, NIHR Oxford Biomedical Research Centre, Spanish Ministry of Science and Innovation, Korea Disease Control and Prevention Agency, Torsten Söderberg Foundation, Stockholm County Council, Swedish Research Council, German Federal Ministry of Health, Robert Koch Institute, Pfizer, Merck, and the Greek National Public Health Organization

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three genomic nomenclature systems to all sequence data from the World Health Organization European Region available until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation, compare the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2

High optical quality models for flow visualization and PIV measurement

Visualization of internal flow or PIV measurements in areas of real pipe elements is a method commonly used in flow studies. For these applications, transparent models with very complex internal geometries are required. Key features of the model are the high-quality optical access, which ideally allows to obtain image of the whole measured area without deformation and with noise suppression. The technology of 3d printing in combination with casting allows the production of almost any type of transparent models of piping elements. Models produced using this technique have almost ideal optical properties. By using index-matching fluid, optical distortions as well as reflections and refractions of light on the inner edges of the model are suppressed. The paper presents the results of visualization and 2D PIV measurements in the model of the globe valve with adjustable valve plug. The valve’s inner geometry was rapid prototyped using a water-soluble material and casted with clear silicone Sylgard 184 under vacuum. The model exhibits excellent optical properties for PIV measurements, especially in the vicinity of walls

Effect of Roller Pump Pulse in the Arterial Needle Area during Hemodialysis

Vascular access is a lifeline for hemodialysis patients. Its lifetime is affected by many hemodynamic factors such as pressure, flow regime and wall shear stress. During hemodialysis, changes in hemodynamic parameters occur due to the flow from needles inserted into the vascular system. Primarily, there is a change in shear stress that affects the vascular wall. Pathological effects of high or low WSS are known. The effect of jet from a venous needle on hemodynamics parameters was studied, but the influence of the arterial needle on hemodynamics parameters is not sufficiently studied. To understand its possible effects, we performed in vivo and in vitro studies. Methods. In vivo experiment: The existence of flow reversal around the suction needle was visualized in a group of 12 randomly selected patients using ultrasound velocity profiling (Doppler ultrasonography) during hemodialysis. In vitro experiment: The flow field was measured using the stereo particle image velocimetry method (stereo PIV). Two regimes were studied. In the first regime, the fluid in the extracorporeal circuit was pumped by a peristaltic pump. In the second regime, the continuous pump was used in the extracorporeal circuit. The conditions were set to resemble those in vascular access during a hemodialysis session. Flow volume was set to 600 mL/min for vascular access and 200 mL/min for the extracorporeal circuit. Results. The main finding of this study was that the wall in the region of the arterial needle was stressed by backflow through the arterial needle. Since this was a variable, low-shear stress loading, it was one of the risk factors for the development of stenosis. Cyclic flow reversal was apparent in all of the included hemodialysis patients. The stereo PIV in vitro experiment revealed the oscillating character of wall shear stress (WSS) inside the model. High shear stress was documented upstream of the injection point of the arterial needle. An area of very low WSS was detected right behind the injection point during a pulse of the peristaltic pump. The minimal and maximal values of the WSS during a pulse of the peristaltic pump in the observed area were −0.7 Pa and 6 Pa, respectively. The distribution of wall shear stress with the continual pump used in the extracorporeal circuit was similar to the distribution during a pulse of the peristaltic one. However, the WSS values were continual; the WSS did not oscillate. WSS ranged between 4.8 Pa and 1.0 Pa