Thermoviscoplastic modelling of asymmetric effects for polymers at large strains

AbstractGlassy polymers such as polycarbonate exhibit different behaviours in different loading scenarios, such as tension and compression. To this end a flow rule is postulated within a thermodynamic consistent framework in a mixed variant formulation and decomposed into a sum of weighted stress mode related quantities. The different stress modes are chosen such that they are accessible to individual examination in the laboratory, where tension and compression are typical examples. The characterisation of the stress modes is obtained in the octahedral plane of the deviatoric stress space in terms of the Lode angle, such that stress mode dependent scalar weighting functions can be constructed. Furthermore the numerical implementation of the constitutive equations into a finite element program is briefly described. In a numerical example, the model is used to simulate the laser transmission welding process

Australian critical care nurses’ knowledge, preparedness and experiences of managing SARS-COV-2 and COVID-19 pandemic

BackgroundCoronavirus disease 2019 (COVID-19) has again highlighted the crucial role of healthcare workers in case management, disease surveillance, policy development, and healthcare education and training. The ongoing pandemic demonstrates the importance of having an emergency response plan that accounts for the safety of frontline healthcare workers, including those working in critical care settings.ObjectivesThe aim of the study was to explore Australian critical care nurses' knowledge, preparedness, and experiences of managing patients diagnosed with severe acute respiratory syndrome coronavirus 2 infection (SARS-CoV-2) and COVID-19.MethodsAn exploratory cross-sectional study of Australian critical care nurses was conducted between June and September 2020. An anonymised online survey was sent to Australian College of Critical Care Nurses' members to collect information about their knowledge, preparedness, and experiences during the COVID-19 pandemic. Descriptive statistics were used to summarise and report data.ResultsA total of 157 critical care nurses participated, with 138 fully complete surveys analysed. Most respondents reported 'good' to 'very good' level of knowledge about COVID-19 and obtained up-to-date COVID-19 information from international and local sources. Regarding managing patients with COVID-19, 82.3% felt sufficiently prepared at the time of data collection, and 93.4% had received specific education, training, or instruction. Most participants were involved in assessing (89.3%) and treating (92.4%) patients with COVID-19. Varying levels of concerns about SARS-CoV-2 infection were expressed by respondents, and 55.7% thought the pandemic had increased their workload. The most frequent concerns expressed by participants were a lack of appropriate personal protective equipment (PPE) and fear of PPE shortage.ConclusionsWhile most nurses expressed sufficient preparedness for managing COVID-19 patients, specific education had been undertaken and experiential learning was evident. Fears of insufficient or lack of appropriate PPE made the response more difficult for nurses and the community. Preparedness and responsiveness are critical to successful management of the COVID-19 pandemic and future outbreaks of emerging infectious diseases

Localization Error Bounds for 5G mmWave Systems under I/Q Imbalance

Location awareness is expected to play a significant role in 5G millimeter-wave (mmWave) communication systems. One of the basic elements of these systems is quadrature amplitude modulation (QAM), which has in-phase and quadrature (I/Q) modulators. It is not uncommon for transceiver hardware to exhibit an imbalance in the I/Q components, causing degradation in data rate and signal quality. Under an amplitude and phase imbalance model at both the transmitter and receiver, 2D positioning performance in 5G mmWave systems is considered. Towards that, we derive the position and orientation error bounds and study the effects of the I/Q imbalance parameters on the derived bounds. The numerical results reveal that I/Q imbalance impacts the performance similarly, whether it occurs at the transmitter or the receiver, and can cause a degradation up to 12% in position and orientation estimation accuracy

Very strong intrinsic supercurrent carrying ability and vortex avalanches in (Ba,K)Fe2As2 superconducting single crystals

We report that single crystals of (Ba,K)Fe2As2 with Tc = 32 K have a pinning potential, U0, as high as 10^4 K, with U0 showing very little field depend-ence. In addition, the (Ba,K)Fe2As2 single crystals become isotropic at low temperatures and high magnetic fields, resulting in a very rigid vortex lattice, even in fields very close to Hc2. The rigid vortices in the two dimensional (Ba,K)Fe2As2 distinguish this compound from 2D high Tc cuprate superconductors with 2D vortices, and make it being capable of cearrying very high critical current.Flux jumping due to high Jc was also observed in large samples at low temperatures.Comment: 4 pages, 7 figures. submitte

A statistical data-based approach to instability detection and wear prediction in radial turning processes

Radial turning forces for tool-life improvements are studied, with the emphasis on predictive rather than preventive maintenance. A tool for wear prediction in various experimental settings of instability is proposed through the application of two statistical approaches to process data on tool-wear during turning processes: three sigma edit rule analysis and Principal Component Analysis (PCA). A Linear Mixed Model (LMM) is applied for wear prediction. These statistical approaches to instability detection generate results of acceptable accuracy for delivering expert opinion. They may be used for on-line monitoring to improve the processing of different materials. The LMM predicted significant differences for tool wear when turning different alloys and with different lubrication systems. It also predicted the degree to which the turning process could be extended while conserving stability. Finally, it should be mentioned that tool force in contact with the material was not considered to be an important input variable for the model.The work was performed as a part of the HIMMOVAL (Grant Agreement Number: 620134) project within the CLEAN-SKY program, linked to the SAGE2 project for geared open-rotor development and the delivery of the demonstrator part. Funding through grant IT900-16 is also acknowledged from the Basque Government Department of Education, Universities and Research

Left-Right Symmetry and Supersymmetric Unification

The existence of an SU(3) X SU(2)_L X SU(2)_R X U(1) gauge symmetry with g_L = g_R at the TeV energy scale is shown to be consistent with supersymmetric SO(10) grand unification at around 1O^{16} GeV if certain new particles are assumed. The additional imposition of a discrete Z_2 symmetry leads to a generalized definition of R parity as well as highly suppressed Majorana neutrino masses. Another model based on SO(10) X SO(10) is also discussed.Comment: 11 pages, 2 figures not included, UCRHEP-T124, Apr 199