Numerical modelling and simulation in sheet metal forming

The application of numerical modelling and simulation in manufacturing technologies is looking back over about a 20–30 years history. In recent years, the role of modelling and simulation in engineering and in manufacturing industry has been continuously increasing. It is well known that during manufacturing processes simultaneous the effect of many different parameters can be observed. This is the reason why in former years, detailed analysis of manufacturing processes could have been done only by time-consuming and expensive trial-and-error methods. Due to the recent developments in the methods of modelling and simulation, as well as in computational facilities, modelling and simulation has become an everyday tool in engineering practice. Besides the aforementioned facts, the emerging role of modelling and simulation can also be explained by the growing globalisation and competition of the world market requiring shorter lead times and more cost effective solutions. In spite the enormous development of hardware and software facilities, the exclusive use of numerical modelling still seems to be very time- and cost consuming, and there is still often a high scepticism about the results among industrialists. Therefore, the purpose of this paper is to overview the present situation of numerical modelling and simulation in sheet metal forming, mainly from the viewpoint of scientific research and industrial applications

New Directions for Public Speaking: The Perfect Pendulum Swings

The author will present her personal and frank ideas of what she sees as a dangerous trend in public speaking events. A loose analogy of forensics to a swinging pendulum will first be explained. Then the author will explain what she sees as the current state of public speaking events, and finally, an attempt to predict some outcomes for the future of public speaking events and some suggestions for our consideration. The aim of this paper is to make us think: where are we in this quest for excellence in public speaking events? How did we get to where we are and where do we go from here

The Magellanic Bridge: The Nearest Purely Tidal Stellar Population

We report on observations of the stellar populations in twelve fields spanning the region between the Magellanic Clouds, made with the Mosaic-II camera on the 4-meter telescope at the Cerro-Tololo Inter-American Observatory. The two main goals of the observations are to characterize the young stellar population (which presumably formed in situ in the Bridge and therefore represents the nearest stellar population formed from tidal debris), and to search for an older stellar component (which would have been stripped from either Cloud as stars, by the same tidal forces which formed the gaseous Bridge). We determine the star-formation history of the young inter-Cloud population, which provides a constraint on the timing of the gravitational interaction which formed the Bridge. We do not detect an older stellar population belonging to the Bridge in any of our fields, implying that the material that was stripped from the Clouds to form the Magellanic Bridge was very nearly a pure gas.Comment: 19 pages, 9 figures. Accepted to Ap

Hypernatural Numbers as Ultrafilters

In this paper we present a use of nonstandard methods in the theory of ultrafilters and in related applications to combinatorics of numbers

The Relationship of Instruments’ Size and Shape to Handwriting Achievement

This experiment is concerned with the design of handwriting instruments. It is the purpose of this experiment to determine if the Zaner-Bloser finger-fitting instruments have any advantages as to speed and quality of handwriting over the conventional instruments as regularly used at sixth grade level

Parent Psychopathology, Marital Adjustment, and Child Psychological Dysfunction: The Mediating Role of Attachment and Sibling Relationship

This study is part of a larger research project examining family attachment processes. The current study tests a family process model that postulates the mediating role of parent-child attachment and sibling relationship quality in the associations of parent psychopathology or marital adjustment to children's psychological dysfunction. A community sample of 86 families with at least one school-aged (8-12 years) child was recruited from area schools and organizations. Families came to the UNT Family Attachment Lab, where they participated in research tasks, including interviews, self-report instruments, and videotaped interaction tasks. Specific questionnaires used in this study included the Sibling Relationship Questionnaire, the Security Scale, the Behavior Assessment System for Children, the Symptom Assessment-45 Questionnaire, and the Dyadic Adjustment Scale. Using a single indicator for each variable, path analyses tested three paternal models, three maternal models, and three systemic models using different informants' (i.e., father, mother, child) reports of child functioning as the outcome variable. Results of this study highlight the positive relationship between parent marital adjustment and parent-child attachment security, as well as the inverse relationship between maternal psychopathology and mother-child attachment security. In addition, the inverse relationship between parent-child attachment security and child psychological dysfunction was significant across nearly all paternal and maternal models. Particularly noteworthy was the consistent mediating influence of attachment security in the association between marital adjustment and child psychological dysfunction across paternal and maternal models

Determination of local material properties of OSB sample by coupling advanced imaging techniques and morphology-based FEM simulation

This is the publisher’s final pdf. The published article is copyrighted by Walter de Gruyter & Co. and can be found at: http://www.degruyter.com/.The goal was to determine local mechanical properties inside of oriented strand board (OSB) based on a realistic morphology-based finite element (FE) model and data acquired from a physical test performed on the same material. The spatial information and local grayscale intensity from CT-scans obtained from small OSB sample was transformed into a 2D regular morphology-based FE mesh with corresponding material properties. The model was then used to simulate the actual compression test performed on the specimen using simplified boundary conditions. The simulated strain fields from the model were compared with the actual strain field measured on the specimen surface during the compression test by means of a full-field optical method, named digital image correlation (DIC). Finally, the original set of material properties was adjusted by an iterative procedure to minimize the difference between the simulated and the measured strain data. The results show that the developed procedure is useful to find local material properties as well as for morphological modeling without the need of segmentation of the image data. The achieved results serve as a prerequisite for full 3D analyses of the complex materials

funcX: A Federated Function Serving Fabric for Science

Exploding data volumes and velocities, new computational methods and platforms, and ubiquitous connectivity demand new approaches to computation in the sciences. These new approaches must enable computation to be mobile, so that, for example, it can occur near data, be triggered by events (e.g., arrival of new data), be offloaded to specialized accelerators, or run remotely where resources are available. They also require new design approaches in which monolithic applications can be decomposed into smaller components, that may in turn be executed separately and on the most suitable resources. To address these needs we present funcX---a distributed function as a service (FaaS) platform that enables flexible, scalable, and high performance remote function execution. funcX's endpoint software can transform existing clouds, clusters, and supercomputers into function serving systems, while funcX's cloud-hosted service provides transparent, secure, and reliable function execution across a federated ecosystem of endpoints. We motivate the need for funcX with several scientific case studies, present our prototype design and implementation, show optimizations that deliver throughput in excess of 1 million functions per second, and demonstrate, via experiments on two supercomputers, that funcX can scale to more than more than 130000 concurrent workers.Comment: Accepted to ACM Symposium on High-Performance Parallel and Distributed Computing (HPDC 2020). arXiv admin note: substantial text overlap with arXiv:1908.0490

Multi-layer study of wave propagation in sunspots

We analyze the propagation of waves in sunspots from the photosphere to the chromosphere using time series of co-spatial Ca II H intensity spectra (including its line blends) and polarimetric spectra of Si I 10827 and the He I 10830 multiplet. From the Doppler shifts of these lines we retrieve the variation of the velocity along the line-of-sight at several heights. Phase spectra are used to obtain the relation between the oscillatory signals. Our analysis reveals standing waves at frequencies lower than 4 mHz and a continuous propagation of waves at higher frequencies, which steepen into shocks in the chromosphere when approaching the formation height of the Ca II H core. The observed non-linearities are weaker in Ca II H than in He I lines. Our analysis suggests that the Ca II H core forms at a lower height than the He I 10830 line: a time delay of about 20 s is measured between the Doppler signal detected at both wavelengths. We fit a model of linear slow magnetoacoustic wave propagation in a stratified atmosphere with radiative losses according to Newton's cooling law to the phase spectra and derive the difference in the formation height of the spectral lines. We show that the linear model describes well the wave propagation up to the formation height of Ca II H, where non-linearities start to become very important.Comment: Accepted by The Astrophysical Journa