Advanced interface models for metal forming simulations

Friction and heat transfer in metal forming simulations are usually restricted by software to be interface constants, a situation not reflected by the mechanics of real manufacturing processes. A better simulation approach is to use a micromechanics based method to estimate friction and heat transfer as evolutionary phenomenon. This paper presents a friction and heat transfer module for hot forging simulations. The friction model is based on a lubricant film thickness calculation using the Reynolds equation, and a calculation of the fractional contact area based on asperity flattening and roughening. Friction is then portioned between asperity and lubricant contacts. Heat transfer coefficients are calculated using a new model for heat conduction through asperity contact patches and lubricant that takes into account the restriction to heat flow at the contacts. The program is implemented as a user routine in a popular commercially available finite element code, DEFORM 2D.Schmid, SR.; Liu, J.; Sellés Cantó, MÁ.; Pasang, T. (2013). Advanced interface models for metal forming simulations. Computational Materials Science. 79:763-771. doi:10.1016/j.commatsci.2013.07.025S7637717

Primary Dendrite Distribution and Disorder During Directional Solidification of Pb-Sb Alloys

Pb-2.2 wt pct Sb and Pb-5.8 wt pet Sb alloys have been directionally solidified from a single-crystal seed with its [100] orientation parallel to the growth direction, to examine the primary dendrite distribution and disorder of the dendrite arrays. The dendrite distribution and ordering have been investigated using analysis techniques such as the Gauss-amplitude fit to the frequency distribution of nearest and higher-order spacings, minimum spanning tree (MST), Voronoi polygon, and Fourier transform (FT) of the dendrite centers. Since the arrangement of dendrites is driven by the requirement to accommodate side-branch growth along the (100) directions, the FT images of the fully developed dendrite centers contain spots which indicate this preferred alignment. A directional solidification distance of about three mushy-zone lengths is sufficient to ensure a steady-state dendritic array, in terms of reaching a constant mean primary spacing. However, local dendrite ordering continues throughout the directional solidification process. The interdendritic convection not only decreases the mean primary spacing, it also makes the dendrite array more disordered and reduces the ratio of the upper and lower spacing limits, as defined by the largest 5 pct and the smallest 5 pct of the population

AlGaInN laser diode technology for free-space and plastic optical fibre telecom applications

Gallium Nitride laser diodes fabricated from the AlGaInN material system is an emerging technology for laser sources from the UV to visible and is a potential key enabler for new system applications such as free-space (underwater & air bourne links) and plastic optical fibre telecommunications. We measure visible light (free-space and underwater) communications at high frequency (up to 2.5 Gbit/s) and in plastic optical fibre (POF) using a directly modulated GaN laser diode

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Influence of chlorinated water on the development of allergic diseases - an overview

Indoor swimming pools can be used all year round and serve for one of the most popular sport pursued for recreation The positive effect of swimming arises in particular from the involvement of all the muscles of the body, decreasing the burden on the joints, as well as functional improvement of both the lungs and heart. Chlorine is typically used to disinfect swimming pool water and as a result the changes that take place lead to the formation of by-products, such as monochloramines (NH2Cl), dichloramines (NH2Cl2) i trichloramines (NH2Cl3), trihalogenometans (THM) or haloacetic acid (HAA). The highest concentration of these substances is just above the water surface and they may cause irritation of skin, eyes and mucosa of the respiratory tract. The toxic effect of high chlorine concentration and its side-products on the respiratory system is known, but the effect of low concentrations of these compounds is still not fully determined. Recent studies suggest that development of allergic diseases among swimmers may be increased by epithelial disorders driven by airway barrier dysfunction caused by chlorine irritation. Swimming in chlorinated water may be linked to symptoms of bronchial hyperreactivity, asthma and rhinitis especially in children, elite swimmers and employees of indoor swimming pools. Hypersensivity pneumonitis related to the use of swimming pools may manifest as a swimming pool or sauna user lung, most commonly caused by water polluting pathogens. The article summarizes recent data concerning the influence of chlorinated water on the development of allergic diseases

On BF-perfect graphs

SIGLETIB: RO 1829 (1985,34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman