Folding-shearing:Shrinking and stretching sheet metal with no thickness change

50% of all sheet metal is scrapped, mainly by trimming following deep-drawing. To combat this a novel process inspired by the mechanics of spinning is proposed and its feasibility is tested with a novel experimental rig. A sheet is first folded along its long axis and then drawn through a die-set in a state of shear to reduce its width with no average reduction of thickness. The performance and limits of the process are evaluated with a novel experimental rig and new analytical and numerical simulations. The extension from this pre-cursor process to a more general forming process is discussed.</p

Artımlı Sac Şekillendirme Yönteminin Sayısal Analizinde Açık Adım Ve Kapalı Adım Sonlu Eleman Yöntemi Çözümlerinin Karşılaştırmalı Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Sacın belirli bir pot çemberine bağlanarak bir şekillendirme ucu vasıtası ile değişik noktalardan uygulanan kuvvet ile (bu kuvvetin oluşturduğu lokal plastik deformasyonlar yolu ile) şekillendirilmesi yöntemine Artımlı Sac Şekillendirme (ASŞ) tekniği denmektedir. İşlem çoğunlukla sayısal kontrollü (CNC) dik işleme tezgahlarında gerçekleştirilmektedir. ASŞ, özellikle şekillendirme sırasında bir kalıp gerektirmemesi ve bu sebeple hem maliyetinin düşük olması hem de üretim esnekliği sağlaması açısından prototip ve/veya konsept üretim benzeri düşük adetli üretimler için uygun bir imalat yöntemidir. Artımlı sac şekillendirme işlemi, seçilen parça geometrisine göre uzun süren bir yöntemdir. Ayrıca şekillendirme sırasında parçanın çeperleri istenenden fazla incelebilmekte ya da yırtılabilmektedir. Bu sebeplerden dolayı, imalat öncesinde ilgili geometrinin üretiminde seçilen takımyolu ve diğer parametrelerin sayısal bir ortamda denenerek etkinliğinin ve doğruluğunun tespit edilmesi önem arz etmektedir. Bu durum, bu çalışmanın temel motivasyonunu oluşturmaktadır. Bu çalışmada, kesik koni ve kare piramit şekillerine sahip iki ayrı parça geometrisi için öncelikle belirlenen takımyolları sonlu elemanlar yöntemi kullanılarak açık adım (explicit) ve kapalı adım (implicit) analizler ile incelenmiştir. Takımyolları üç değişik şekillendirme ucu çapı için (5mm, 10mm ve 15mm) hazırlanmıştır. Hazırlanan takımyolları MATLAB programı vasıtası ile oluşturulan bir arayüz dosyası ile ABAQUS sonlu elemanlar yazılımına girdi olarak verilmiştir. Ayrıca malzemenin detaylı simülasyona yönelik mekanik özellikleri hassas şekilde tespit edilmiş ve bu bilgiler de ilgili sonlu elemanlar yöntemi programına malzeme kartları olarak yerleştirilmiştir. Çalışmada analizleri yapılan parçaların daha sonra imalatları gerçekleştirilmiş ve imal edilen parçalar üzerinden optik ölçüm yöntemi ile hem geometrik bilgi (ölçüler ve toleranslar) hem de genleme değerleri elde edilmiştir. Optik ölçümler için GOM-Atos ve Argus optik ölçüm sistemleri kullanılmıştır. Belirli bir kesit boyunca ölçümler karşılaştırıldığında gerek açık adım gerekse kapalı adım çözümlerinin oldukça iyi sonuçlar verdiği görülebilir. Ancak çözümler kalınlık değişmesi açısından karşılaştırıldığında kapalı adım çözümlerin açık adım çözümlerine göre çok daha iyi sonuç verdiği değerlendirilmektedir. Anahtar kelimeler: artımlı sac şekillendirme, sonlu eleman yöntemi, kalıpsız şekillendirm

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Management of heart failure complicating acute coronary syndromes in Montenegro and Serbia

It is essential that context-appropriate health research and health interventions take place in countries with economy in transition. The aims of this study were to describe the clinical characteristics, management, and in-hospital outcomes of acute coronary syndrome (ACS) patients with heart failure (HF) in Montenegro and Serbia. The data of this study are a framework of the International Survey of Acute Coronary Syndromes in Transitional Countries (ISACS-TC; NCT01218776), a multi-national and multicentre registry of patients hospitalized with ACS in the European countries that emerged from the Socialist era. The present analysis focused on participants admitted to 15 hospitals in Montenegro and Serbia with a diagnosis of ACS during the period between October 2012 and August 2013. Among 1115 patients, 94 (8.4%) had an admission diagnosis of HF (Killip Class II or III). Heart failure patients were significantly older (P < 0.001). Heart failure was more frequently associated with hypertension. When compared with patients presenting without HF (Killip Class I), those with HF had lower rates of reperfusion therapy either by percutaneous coronary intervention (47.9 vs. 60.7%, P = 0.015) or by fibrinolysis (2.1 vs. 11.8%, P = 0.004). In multivariate logistic regression analysis, older age, prior coronary artery bypass graft, and ST-segment elevation myocardial infarction were the relevant predictor of HF at admission. Heart failure on admission was associated with a marked increase in mortality rates during hospitalization (13.8 vs. 3.7%, P < 0.001). After adjustment for differences in clinical characteristics, HF was still associated with higher mortality (odds ratio 2.88, 95% confidence interval 1.22-6.79, P = 0.016). Heart failure is observed in nearly 9% of patients with ACS in Serbia and Montenegro and is also associated with a significant increase in in-hospital mortality. More aggressive treatment of these patients is warranted to improve prognosi

Effect of Antiplatelet Therapy on Survival and Organ Support–Free Days in Critically Ill Patients With COVID-19

International audienc

Long-term (180-Day) outcomes in critically Ill patients with COVID-19 in the REMAP-CAP randomized clinical trial

Importance The longer-term effects of therapies for the treatment of critically ill patients with COVID-19 are unknown. Objective To determine the effect of multiple interventions for critically ill adults with COVID-19 on longer-term outcomes. Design, Setting, and Participants Prespecified secondary analysis of an ongoing adaptive platform trial (REMAP-CAP) testing interventions within multiple therapeutic domains in which 4869 critically ill adult patients with COVID-19 were enrolled between March 9, 2020, and June 22, 2021, from 197 sites in 14 countries. The final 180-day follow-up was completed on March 2, 2022. Interventions Patients were randomized to receive 1 or more interventions within 6 treatment domains: immune modulators (n = 2274), convalescent plasma (n = 2011), antiplatelet therapy (n = 1557), anticoagulation (n = 1033), antivirals (n = 726), and corticosteroids (n = 401). Main Outcomes and Measures The main outcome was survival through day 180, analyzed using a bayesian piecewise exponential model. A hazard ratio (HR) less than 1 represented improved survival (superiority), while an HR greater than 1 represented worsened survival (harm); futility was represented by a relative improvement less than 20% in outcome, shown by an HR greater than 0.83. Results Among 4869 randomized patients (mean age, 59.3 years; 1537 [32.1%] women), 4107 (84.3%) had known vital status and 2590 (63.1%) were alive at day 180. IL-6 receptor antagonists had a greater than 99.9% probability of improving 6-month survival (adjusted HR, 0.74 [95% credible interval {CrI}, 0.61-0.90]) and antiplatelet agents had a 95% probability of improving 6-month survival (adjusted HR, 0.85 [95% CrI, 0.71-1.03]) compared with the control, while the probability of trial-defined statistical futility (HR >0.83) was high for therapeutic anticoagulation (99.9%; HR, 1.13 [95% CrI, 0.93-1.42]), convalescent plasma (99.2%; HR, 0.99 [95% CrI, 0.86-1.14]), and lopinavir-ritonavir (96.6%; HR, 1.06 [95% CrI, 0.82-1.38]) and the probabilities of harm from hydroxychloroquine (96.9%; HR, 1.51 [95% CrI, 0.98-2.29]) and the combination of lopinavir-ritonavir and hydroxychloroquine (96.8%; HR, 1.61 [95% CrI, 0.97-2.67]) were high. The corticosteroid domain was stopped early prior to reaching a predefined statistical trigger; there was a 57.1% to 61.6% probability of improving 6-month survival across varying hydrocortisone dosing strategies. Conclusions and Relevance Among critically ill patients with COVID-19 randomized to receive 1 or more therapeutic interventions, treatment with an IL-6 receptor antagonist had a greater than 99.9% probability of improved 180-day mortality compared with patients randomized to the control, and treatment with an antiplatelet had a 95.0% probability of improved 180-day mortality compared with patients randomized to the control. Overall, when considered with previously reported short-term results, the findings indicate that initial in-hospital treatment effects were consistent for most therapies through 6 months