Influence of Graphite Additives on Mechanical, Tribological, Fire Resistance and Electrical Properties in Polyamide 6

New types of polymers are usually produced with different additives. In this work, the effect of graphite addition (1.5wt%, 2wt%, 2.5wt%, 3wt% and 3.5wt%) on material’s properties is analysed. Results of current investigation show that there are two possible subtypes (groups) of polyamide, containing 2% and 3.5% graphite, which reveal improved complex properties. By using graphite additives, the material becomes stiffer. In polyamide-2% graphite system, the abrasive wear tends to decrease while the fire resistance improves without significant changes in mechanical properties. In addition to improved tribological and fire resistance behaviour, polyamide with 3.5% graphite addition gains excellent antistatic properties. At the same time, in this material both the tensile and the Charpy impact strengths have decreased by 15% and 30%, respectively, whereas the Young\u27s modulus increases by 6% as a result of dispergation/adhesion between the graphite and polymer

Collaborative Systems, Operation and Task of the Manufacturing Execution Systems in the 21st Century Industry

Until the first two decades of the 21st century, as part of the Enterprise Resourse Planning (ERP), the Manufacturing Execution System (MES) and related systems have undergone development in both complexity and efficiency. In the field of production technology, there are many sources of work nowadays to get a detailed picture of the solutions offered by MES. The purpose of this article is to give a comprehensive overview of the MES solutions that currently used in industry. In addition to the general structure of the systems and Holonic MES are briefly described. Special attencion is paid to various collaborative systems that complement the MES. The additional manufacturing tools for MES is also described shematically in this article

A novel measuring technique to evaluate frictional characteristics of roll-slip contacts in polymer-metal pairs

Tribology research is aimed for desirable frictional characteristic; especially in rolling/sliding of polymer-metal contacts which helps smooth operations and energy savings. Conventional roll-slip tests for few million cycles have significant deposit of polymer transfer layer on counterface, thus having a polymer-polymer contact instead of polymer-metal contact. Besides, backtransfer affecting the friction force was never explored. Studying these phenomenon individually and characterizing frictional property without the presence of transfer layer helps for a better understanding of the combined system. A new procedure for measuring friction torque at 20% slip ratio is adapted for varying speeds from 10 to 500 rpm. The observed friction-force increases rapidly at low-speeds and becomes linear at high-speeds. The micrographs of the contact surface prove no trace of transfer layer was found in the newly developed measuring process. Also specimen surface temperature never reached the effective level to affect friction properties

Characterization of surface morphology and its correlation with friction performance of brake pads

The present work presents the morphology evolution of a brake material surface submitted to braking tests through a laboratory-scale tribometer. Optical microscope images of the material’s surface were obtained for every 10 braking operations. These images were post-processed in appropriate computational software. By means of the image segmentation technique, morphological parameters related to the brake material surface were estimated. The wear rate and also the coefficient of friction resulting from the tests were measured. For the NAO material used in this study, the friction behaviour revealed to be strongly associated with the amount of contact plateaus. Besides, the mean area of the contact plateaus was the main factor responsible for increasing the real contact area of the friction material. The higher wear rate observed in the first braking operations can be mainly attributed to the higher surface roughness measured in this condition. As the braking operations progress, the plateaus becomes flatter and wear rate is reduced. Finally, the image segmentation technique proved adequate for investigating morphological aspects in friction material surface

Surface plastic flow of three-dimensional printed polylactic acid in the tribological study of surface patterned polymer

The potential of three-dimensional (3D) printing in polymer tribology is poorly explored. Material alignment and composition play vital roles in altering the friction and wear characteristics of 3D printed materials. In the current study, 3D patterns made by fused deposition modelling are used to print advanced tribo-composites. Two different surface patterns (line and circular) are provided through 3D printing using white and silver polylactic acid (PLA). The deformation and distribution of white and silver PLA over the samples surface are observed after a wear test. Results showed that the coefficient of friction is not influenced by changes in the surface pattern. However, the wear rate increased for samples with line patterns on the contact surface, since plastic flow was more significant in this case. Moreover, the filling factor exhibited an influence on increasing the plastic flow of the contact surface for samples with a line pattern

Trade Flows and Trade Specialisation: The Case of China

Using annual data for the periods 1992–2012, this paper examines trade flows between China and its main trade partners in Asia, North America and Europe, and whether increasing trade has led to industrial structural adjustment and changes in China's trade patterns. The analysis is based on both economic indicators and the estimation of a gravity model, and applies recently developed panel data methods that explicitly take into account unobserved heterogeneity, specifically the fixed effect vector decomposition (FEVD) technique. The findings confirm the significant change in China's trading structure associated with the fast growth of foreign trade. In particular, there has been a shift from resource- and labour-intensive to capital- and technology-intensive exports

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

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