3,607 research outputs found
Flow-based approach for holistic factory engineering and design
The engineering of future factories requires digital tools along life cycle phases from investment planning to ramp-up. Manufacturers need scientific-based integrated highly dynamic data management systems for the participative and integrated factory planning. The paper presents a new approach for the continuously integrated product design, factory and process planning, through a service-oriented architecture for the implementation of digital factory tools. A first prototype of the digital factory framework has been realised by a comprehensive scenario for factory, equipment and process planning. The phases of factory operation and equipment maintenance are integrated, as well. The enabling technologies, grid computing and workflow management, which supports the comprehensive and integrated engineering of products, factory and processes are shortly introduced
An energetic approach in thermomechanical fatigue for silicium molybden cast iron
The purpose of this paper is to define a low cycle fatigue criterion in order to predict the failure of engineering structures. The major problem in defining a predictive fatigue criterion is that it should be applicable for structures submitted to complex multiaxial thermo-mechanical loadings but should be identifiable from simple experiments on specimens. After a short critical review of the principal criteria used in low cycle fatigue it will be shown that the dissipated energy per cycle permits a correlation of isothermal and anisothermal results obtained on silicon molybdenum cast iron in the case of specimens and also on structures
THE PRODUCTIVITY OF SOME WHEAT VARIETIES IN THE SOIL AND CLIME CONDITIONS FROM SOUTH-WESTERN ZONE OF MEHEDINTI COUNTY
The researches aimed the comparative study of some winter wheat varieties in conventional cropping system in the conditions of reddish preluvosoil from Vanju Mare, on a 400 ha surface for a better knowing of their features in order to recommend them for cropping. During two years (2016 – 2017) there have been cropped the following wheat crop kinds: Glossa – romanian variety and two austrian varieties: Balaton and Astardo.Regarding the yield obtained by Glossa variety, it recorded an average of 6.100 kg/ha and Balaton and Astardo varieties, an average yield of 7200 kg/ha. The high yield recorded by austrian varieties is due to the fact that they belong to Premium group, very productive, very tolerant to drought and with high ecological plasticity, with good winter resistance, high tillering capacity, highly receptive to fertilizers and superior as quality. The biologic potential is very high, reaching 11.000 kg/ha. The protein content of the wheat grain depends on the following factors: the variety, the cropping technology (irrigation, fertilization) and the soil and clime conditions. Good protein content determines a good baking quality. Among the technological factors, the fertilization is the most important that increases the protein content of the wheat kernels. The wet gluten content and the falling index are favorably influenced by the nitrogen fertilizer applying. There is recommended the cropping of wheat varieties that have a high production capacity, with a good resistance to the main risk factors of the clime, with tolerance to the main foliar diseases, with superior quality indicators from different maturity classes
Asymptotic results for renewal risk models with risky investments
We consider a renewal jump-diffusion process, more specifically a renewal insurance risk model with investments in a stock whose price is modeled by a geometric Brownian motion. Using Laplace transforms and regular variation theory, we introduce a transparent and unifying analytic method for investigating the asymptotic behavior of ruin probabilities and related quantities, in models with light- or heavy-tailed jumps, whenever the distribution of the time between jumps has rational Laplace transform
Sonographic Wrist Measurements and Detection of Anatomical Features in Carpal Tunnel Syndrome
INTRODUCTION: This study compares anatomical findings at wrist level in patients with known carpal tunnel syndrome (CTS) and controls by ultrasonography (US).
MATERIAL AND METHODS: Wrist-US investigations of 28 consecutive patients with 38 diagnosed, idiopathic CTS were compared to 49 healthy volunteers without history of CTS. Internal wrists dimensions, the presence of flexor muscle bellies in the carpal tunnel, and cross-sectional area of the median nerve were analyzed. The findings were correlated to gender, age, and BMI.
RESULTS: US demonstrated a square internal carpal tunnel configuration in CTS patients compared to controls (P < 0.001). Patients with CTS showed a trend towards the presence of flexor muscles bellies in the carpal tunnel (odds ratio 1.77, 95% CI 0.337-8.33). CTS was present in women with higher BMI (P = 0.015).
CONCLUSION: US allowed detection of specific anatomical features at wrist level in CTS patients. This observation may enable--following confirmation in larger prospective studies--risk evaluation for CTS development
Thomas-Fermi Calculations of Atoms and Matter in Magnetic Neutron Stars II: Finite Temperature Effects
We present numerical calculations of the equation of state for dense matter
in high magnetic fields, using a temperature dependent Thomas-Fermi theory with
a magnetic field that takes all Landau levels into account. Free energies for
atoms and matter are also calculated as well as profiles of the electron
density as a function of distance from the atomic nucleus for representative
values of the magnetic field strength, total matter density, and temperature.
The Landau shell structure, which is so prominent in cold dense matter in high
magnetic fields, is still clearly present at finite temperature as long as it
is less than approximately one tenth of the cyclotron energy. This structure is
reflected in an oscillatory behaviour of the equation of state and other
thermodynamic properties of dense matter and hence also in profiles of the
density and pressure as functions of depth in the surface layers of magnetic
neutron stars. These oscillations are completely smoothed out by thermal
effects at temperatures of the order of the cyclotron energy or higher.Comment: 37 pages, 17 figures included, submitted to Ap
Optical alignment and spinning of laser-trapped microscopic particles
Light-induced rotation of absorbing microscopic particles by transfer of
angular momentum from light to the material raises the possibility of optically
driven micromachines. The phenomenon has been observed using elliptically
polarized laser beams or beams with helical phase structure. But it is
difficult to develop high power in such experiments because of overheating and
unwanted axial forces, limiting the achievable rotation rates to a few hertz.
This problem can in principle be overcome by using transparent particles,
transferring angular momentum by a mechanism first observed by Beth in 1936,
when he reported a tiny torque developed in a quartz waveplate due to the
change in polarization of transmitted light. Here we show that an optical
torque can be induced on microscopic birefringent particles of calcite held by
optical tweezers. Depending on the polarization of the incident beam, the
particles either become aligned with the plane of polarization (and thus can be
rotated through specified angles) or spin with constant rotation frequency.
Because these microscopic particles are transparent, they can be held in
three-dimensional optical traps at very high power without heating. We have
observed rotation rates in excess of 350 Hz.Comment: 4 pages, 4 figure
Data-Driven Estimation of Failure Probabilities in Correlated Structure-Preserving Stochastic Power System Models
We propose a data-driven approach for propagating uncertainty in stochastic
power grid simulations and apply it to the estimation of transmission line
failure probabilities. A reduced-order equation governing the evolution of the
observed line energy probability density function is derived from the
Fokker--Planck equation of the full-order continuous Markov process. Our method
consists of estimates produced by numerically integrating this reduced
equation. Numerical experiments for scalar- and vector-valued energy functions
are conducted using the classical multimachine model under spatiotemporally
correlated noise perturbation. The method demonstrates a more sample-efficient
approach for computing probabilities of tail events when compared with kernel
density estimation. Moreover, it produces vastly more accurate estimates of
joint event occurrence when compared with independent models.Comment: 12 pages, 6 figures, and 1 tabl
Effect of sting size on the wake of a sphere at subcritical Reynolds numbers
Vortex shedding and turbulent motion in the wake of a sphere that is supported using
a streamwise-aligned cylindrical sting are investigated at a subcritical Reynolds number of
Re=3800, using high speed particle image velocimetry. The mechanism by which the presence of a sting of increasing diameter relative to the diameter of the sphere influences the wake, in terms of both the small-scale shear instability and the larger wake instability, is
explored and brie
y compared with the two-dimensional analog of the splitter plate introduced into a cylinder wake. The difficulties associated with obtaining converged statistics,
along with the effect of free stream turbulence and sphere vibrations are detailed. An
understanding of the mechanism by which the blockage, or interference, arising from the
presence of the sting influences cross-wake communication and downstream development
is a necessary precursor to studies of active control of the wake using surface actuation on
a sting-mounted sphere
Concomitant endocarditis and spondylodiscitis due to coagulase-negative Staphylococci and a review of the literature
Background: Coagulase-negative staphylococci (CoNS) are part of the normal skin flora. Although CoNS are generally considered as low pathogenic microorganisms, they can cause serious infections, particularly in the context of foreign body material. Case report: Here we present two cases of concomitant infectious endocarditis and spondylodiscitis; one caused by S. epidermidis, the other by S. haemolyticus. Additionally, we reviewed the literature for previously reported cases of concomitant endocarditis and spondylodiscitis due to CoNS. Conclusion: In patients with back pain and a cardiac device in situ, CoNS should be considered as causative pathogens for possible endocarditis and/or spondylodiscitis, and should not be regarded as contamination.</p
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