102,573 research outputs found
Burnishing of AM Materials to Obtain High Performance Part Surfaces
No full textPurpose: This paper aims to provide a flexible solution to include additive manufacturing into a process chain complying with Industry 4.0 pillars, overcoming major drawbacks in terms of reliability and experimental effort. Design/methodology/approach: The study is based on the combination of real experimental activities and simulated ones. Findings: The main findings of this work consist into validation of the proposed process chain, which proves to be effective in terms of process flexibility (additive manufacturing, burnishing and process simulation acting synergistically), cost and time reduction and final output quality, encouraging customer involvement towards customization. Originality/value: This paper contributes to current research on the application of burnishing process, an easy to implement and environmentally friendly post-processing method to improve the performance of AM products, by providing a unique perspective integrating a reliable simulation model. Other researchers can employ these outcomes towards manufacturing of the future. A reduced version of this work has been previously published in Procedia Computer Science (Sanguedolce, Rotella, Saffioti & Filice, 2021)
Surface Modifications Induced by Roller Burnishing of Ti6Al4V Under Different Cooling/Lubrication Conditions
No full textThe paper presents a deep analysis of surface modifications induced by roller burnishing process of Ti6Al4V titanium alloy. The extensive experimental campaign has been performed based on a Design of Experiments at varying lubrication/cooling strategies (dry, cryogenic and MQL), roller radius, burnishing speed and burnishing depth. The resulting surface integrity has been analyzed in terms of surface roughness, micro hard-ness, microstructural changes and tribological performance. In particular, the wear rate of the burnished sample has been evaluated as a quality indicator of the process. The overall results show the influence of burnishing process parameters on surface quality and wear resistance of Ti6Al4V highlighting the capability of the process to significantly improve the above performance especially when cryogenic cooling is applied. Finally, the extensive experimental activity allowed to find a combination of processing parameters and lubrication conditions able to significantly improve the surface quality of the final component
Comparison of two Drain Modulator for Multi-Mode Multi-Band Transmitters employing EER Technique
No full textThis paper compares two types of Amplitude Modulator and their applicability in High Power Ampli ̄ers (HPA) with Envelope Elimination and Restoration (EER) technique and Low Voltage supply for the use of multi-mode multi-band terminals: a very °exible terminal plays a key role in the worldwide telecommunications coverage. First of all a HPA with drain e±ciency of 88% that operates at 1.95 GHz was tested with a typical drain modulator, then is shown that a di®erent modulator can achieve a better drain e±ciency but it is going to operate with lower values of modulation index (ma)
Transverse myelitis associated with Mycoplasma pneumoniae pneumonitis: a report of two cases
No full textThe authors report two cases of transverse myelitis due to Mycoplasma pneumoniae occurring during a recent acute infection due to Epstein-Barr virus (EBV). The clinical picture included weakness of the legs, bladder dysfunction, fever, headache and in one case, a mild confusional state. Magnetic Resonance Imaging (MRI) revealed a segmental edema of the lumbar tract and cerebro-spinal fluid analysis showed a mild pleocytosis and an increased level of proteins with a blood-brain barrier damage. The diagnosis of acute infection due to Mycoplasma pneumoniae was made on serological criteria. The patients recovered completely after a 14-day course of an associated regimen with Ciprofloxacin (400 mg/day i.v.) plus prednisone (60 mg/day i.v.). The authors emphasise the immunological disorders in the combined infection with Mycoplasma pneumoniae and EBV, supposing that an infective mononucleosis may predispose to mycoplasmic transverse myelitis
Shape and dimensional accuracy in Single Point Incremental Forming: state of the art and future trends
No full textThe paper is aimed to discuss some relevant issues concerning an innovative sheet metal forming technology, namely Single Point Incremental
Forming. The advantages of this technology are addressed, including its capability to provide effective answers to some impellent industrial
requirements: process flexibility, strong customer orientation, production of highly differentiated goods at low industrial costs. As well some
relevant drawbacks are highlighted, mainly as concerns the level of accuracy permitted by the process.
A wide recognition of the research efforts in this field is presented, taking into account some general considerations on the difference sources of shape and dimensional errors, as well as the influence of the most relevant parameters. Finally, some strategies for error minimisation are presented and discussed
Hepatocellular carcinoma in HIV-infected patients with chronic hepatitis: an emerging issue.
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Management of hepatocellular carcinoma in human immunodeficiency virus-infected patients.
No full textAbstract: Hepatocellular carcinoma (HCC) resulting from chronic infection with hepatitis B or C virus (HBV, HCV) is a significant health problem. Concurrent infection with human immunodeficiency virus (HIV) may accelerate the progression from cirrhosis to HCC. Current guidelines advise screening patients with cirrhosis at 6-month intervals using ultrasonography and measurement of alpha-fetoprotein levels. In early-stage HCC, resection and liver transplantation are curative, as is percutaneous ethanol injection for small tumours in patients who are not candidates for surgery. HIV-infected patients do not qualify for liver transplantation. For late-stage HCC, chemoembolization can improve survival. Prevention of hepatitis and cirrhosis are key goals in reducing the impact of HCC. Numerous issues in HCC prevention, diagnosis, and management still remain to be resolved through large-scale, randomized clinical trials
Epatite virale NonA-NonB : aspetti ultrastrutturali degli epatociti in biopsie ecoguidate con ago sottile (tipo "screw needle") eseguite in fase precoce."
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