92 research outputs found
A cumulus project: design and implementation
The Cloud computing becomes an innovative computing paradigm, which aims to provide reliable, customized and QoS guaranteed computing infrastructures for users. This paper presents our early experience of Cloud computing based on the Cumulus project for compute centers. In this paper, we introduce the Cumulus project with its various aspects, such as design pattern, infrastructure, and middleware
Finite element modeling of an alternating current electromagnetic weld pool support in full penetration laser beam welding of thick duplex stainless steel plates
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in M. Bachmann et al., J. Laser Appl. 28, 022404 (2016) and may be found at https://doi.org/10.2351/1.4943906.An electromagnetic weld pool support system for 20âmm thick duplex stainless steel AISI 2205 was investigated numerically and compared to experiments. In our former publications, it was shown how an alternating current (AC) magnetic field below the process zone directed perpendicular to the welding direction can induce vertically directed Lorentz forces. These can counteract the gravitational forces and allow for a suppression of material drop-out for austenitic stainless steels and aluminum alloys. In this investigation, we additionally adopted a steady-state complex magnetic permeability model for the consideration of the magnetic hysteresis behavior due to the ferritic characteristics of the material. The model was calibrated against the JilesâAtherton model. The material model was also successfully tested against an experimental configuration before welding with a 30âmm diameter cylinder of austenitic stainless steel surrounded by duplex stainless steel. Thereby, the effects of the Curie temperature on the magnetic characteristics in the vicinity of the later welding zone were simulated. The welding process was modeled with a three-dimensional turbulent steady-state model including heat transfer and fluid dynamics as well as the electromagnetic field equations. Main physical effects, the thermo-capillary (Marangoni) convection at the weld pool boundaries, the natural convection due to gravity as well as latent heat of solidâliquid phase transitions at the phase boundaries were accounted for in the model. The feedback of the electromagnetic forces on the weld pool was described in terms of the electromagnetic-induced pressure. The finite element software COMSOL Multiphysics 4.2 was used in this investigation. It is shown that the gravity drop-out associated with the welding of 20âmm thick duplex stainless steel plates due to the hydrostatic pressure can be prevented by the application of AC magnetic fields between around 70 and 90âmT. The corresponding oscillation frequencies were between 1 and 10 kHz and the electromagnetic AC powers were between 1 and 2.3âkW. In the experiments, values of the electromagnetic AC power between 1.6 and 2.4âkW at oscillation frequencies between 1.2 and 2.5âkHz were found to be optimal to avoid melt sagging or drop-out of melt in single pass full-penetration laser beam welding of 15 and 20âmm thick AISI 2205
Cloud Computing: A Perspective Study
The Cloud computing emerges as a new computing paradigm which aims to provide reliable, customized and QoS guaranteed dynamic computing environments for end-users. In this paper, we study the Cloud computing paradigm from various aspects, such as definitions, distinct features, and enabling technologies. This paper brings an introductional review on the Cloud computing and provide the state-of-the-art of Cloud computing technologies
Radiation enhancement and "temperature" in the collapse regime of gravitational scattering
We generalize the semiclassical treatment of graviton radiation to
gravitational scattering at very large energies and finite
scattering angles , so as to approach the collapse regime of impact
parameters . Our basic tool is the
extension of the recently proposed, unified form of radiation to the ACV
reduced-action model and to its resummed-eikonal exchange. By superimposing
that radiation all-over eikonal scattering, we are able to derive the
corresponding (unitary) coherent-state operator. The resulting graviton
spectrum, tuned on the gravitational radius , fully agrees with previous
calculations for small angles but, for sizeable angles
acquires an exponential cutoff of the large
region, due to energy conservation, so as to emit a finite fraction
of the total energy. In the approach-to-collapse regime of we find
a radiation enhancement due to large tidal forces, so that the whole energy is
radiated off, with a large multiplicity and a
well-defined frequency cutoff of order .
The latter corresponds to the Hawking temperature for a black hole of mass
notably smaller than .Comment: 5 pages, 2 figures, talk presented at the European Physical Society
Conference on High Energy Physics, 5-12 July, Venice, Ital
Lessons-learned. Kollegiale und evidenzbasierte Lehrreflexion des ersten Corona-Semesters
Wie bei jedem Unterricht sind auch beim digitalen Lernen die professionelle Begleitung des Lernens und geeignete Inhalte sowie die didaktische Vermittlung entscheidend. Folglich kann nicht davon ausgegangen werden, dass allein durch den Einsatz digitaler Formate die Kompetenzen fĂŒr selbstgesteuertes Lernen zunehmen. Genau in diesem Kontext ist der Beitrag des Forscher*innenteams angesiedelt, die ihre Befunde zur Umsetzung der digitalen Lehre im Sommersemester 2021 an der UniversitĂ€t OsnabrĂŒck dokumentieren. Hier wird unter anderem deutlich, dass Dozierende dazu tendieren, von den Studierenden mehr eigenverantwortliches Lernen zu fordern, ohne ihre UnterstĂŒtzungsangebote entsprechend anzupassen und zu intensivieren. (DIPF/Orig.
The Neurocognitive Assessment in the Metabolic and Aging Cohort (NAMACO) study: baseline participant profile.
The aim of the study was to examine baseline neurocognitive impairment (NCI) prevalence and factors associated with NCI among patients enrolled in the Neurocognitive Assessment in the Metabolic and Aging Cohort (NAMACO) study.
The NAMACO study is an ongoing, prospective, longitudinal, multicentre and multilingual (German, French and Italian) study within the Swiss HIV Cohort Study. Between 1 May 2013 and 30 November 2016, 981 patients â„ 45 years old were enrolled in the study. All underwent standardized neuropsychological (NP) assessment by neuropsychologists. NCI was diagnosed using Frascati criteria and classified as HIV-associated or as related to other factors. Dichotomized analysis (NCI versus no NCI) and continuous analyses (based on NP test z-score means) were performed.
Most patients (942; 96.2%) had viral loads < 50 HIV-1 RNA copies/mL. NCI was identified in 390 patients (39.8%): 263 patients (26.8%) had HIV-associated NCI [249 patients (25.4%) had asymptomatic neurocognitive impairment (ANI)] and 127 patients (13%) had NCI attributable to other factors, mainly psychiatric disorders. There was good correlation between dichotomized and continuous analyses, with NCI associated with older age, non-Caucasian ethnicity, shorter duration of education, unemployment and longer antiretroviral therapy duration.
In this large sample of aging people living with HIV with well-controlled infection in Switzerland, baseline HIV-associated NCI prevalence, as diagnosed after formal NP assessment, was 26.8%, with most cases being ANI. The NAMACO study data will enable longitudinal analyses within this population to examine factors affecting NCI development and course
Anticholinergic and Sedative Medications Are Associated With Neurocognitive Performance of Well Treated People With Human Immunodeficiency Virus.
Background
We previously showed that anticholinergic (ACH) medications contribute to self-reported neurocognitive impairment (NCI) in elderly people with human immunodeficiency virus (PWH). The current cross-sectional study further evaluated the effect of ACH and sedative drugs on neurocognitive function in PWH who underwent comprehensive neuropsychological evaluation.
Methods
A medication review was performed in PWH enrolled in the prospective Neurocognitive Assessment in Metabolic and Aging Cohort within the Swiss HIV Cohort Study. Neurocognitive functions were analyzed in 5 domains (motor skills, speed of information, attention/working memory, executive functions, and verbal learning memory). The effect of ACH and sedative medications on neurocognitive functioning was evaluated using linear regression models for the continuous (mean z-score) outcome and multivariable logistic regression models for the binary (presence/absence) outcome.
Results
A total of 963 PWH (80% male, 92% Caucasian, 96% virologically suppressed, median age 52) were included. Fourteen percent of participants were prescribed â„1 ACH medication and 9% were prescribed â„1 sedative medication. Overall, 40% of participants had NCI. Sedative medication use was associated with impaired attention/verbal learning and ACH medication use with motor skills deficits both in the continuous (mean z-score difference -0.26 to -0.14, Pâ<â.001 and Pâ=â.06) and binary (odds ratio [OR], â„1.67; Pâ<â.05) models. Their combined use was associated with deficits in overall neurocognitive functions in both models (mean z-score difference -0.12, Pâ=â.002 and OR = 1.54, Pâ=â.03). These associations were unchanged in a subgroup analysis of participants without depression (nâ=â824).
Conclusions
Anticholinergic and sedative medications contribute to NCI. Clinicians need to consider these drugs when assessing NCI in PWH
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