607 research outputs found
Development and analysis of train brake curve calculation methods with complex simulation
This paper describes an efficient method using simulation for developing and analyzing train brake curve
calculation methods for the on-board computer of the ETCS system. An application example with actual measurements is
also presented
X-ray propagation through hollow channel: PolyCAD - a ray tracing code (1)
A new CAD program, PolyCAD, designed for X-ray photon tracing in
polycapillary optics is described. To understand the PolyCAD code and its
results, the theoretical basis of X-ray transmission by a single cylindrical
channel (monocapillary) is discussed first. Then the simplest cases of
cylindrically and conically shaped polycapillary optics are examined. PolyCAD
allows any type of X-ray source to be used: an X-ray tube of finite beam
dimensions or an astrophysical object can be simulated in combination with the
polycapillary optics. The radiation distribution images formed on a screen
located at various focal distances are discussed. The good agreement of some of
the PolyCAD results with those reported in earlier papers validate the code.
This is the first paper of a series dedicated to the development of an
exhaustive CAD program, work is in progress to develop the code to include
other polycapillary-optics shapes, such as semi-lenses and full-lenses.Comment: Submitted to Applied Optic
Characterization of Roman glass tesserae from the Coriglia excavation site (Italy) via energy-dispersive X-ray fluorescence spectrometry and Raman spectroscopy
The combined use of handheld energy-dispersive X-ray fluorescence spectrometry, Raman spectroscopy, and micro-energy-dispersive X-ray fluorescence spectrometry permitted the characterization of Roman glass tesserae excavation from the Coriglia (Italy) archeological site. Analyses of ten different glass colors were conducted as spot analyses on intact samples and as both spot analyses and line scans on select cross-sectioned samples. The elemental and molecular information gained from these spectral measurements allowed for the qualitative chemical characterization of the bulk glass, decolorants, opacifiers, and coloring agents. The use of an antimony opacifier in many of the samples supports the late Imperial phasing as determined through numismatic, fresco, ceramics, and architectural evidence. And dealinization of the exterior glass layers caused by the burial environment was confirmed
Unsupervised Domain Adaptation through Inter-Modal Rotation for RGB-D Object Recognition
Unsupervised Domain Adaptation (DA) exploits the supervision of a label-rich source dataset to make predictions on an unlabeled target dataset by aligning the two data distributions. In robotics, DA is used to take advantage of automatically generated synthetic data, that come with 'free' annotation, to make effective predictions on real data. However, existing DA methods are not designed to cope with the multi-modal nature of RGB-D data, which are widely used in robotic vision. We propose a novel RGB-D DA method that reduces the synthetic-to-real domain shift by exploiting the inter-modal relation between the RGB and depth image. Our method consists of training a convolutional neural network to solve, in addition to the main recognition task, the pretext task of predicting the relative rotation between the RGB and depth image. To evaluate our method and encourage further research in this area, we define two benchmark datasets for object categorization and instance recognition. With extensive experiments, we show the benefits of leveraging the inter-modal relations for RGB-D DA. The code is available at: 'https://github.com/MRLoghmani/relative-rotation'
Strain path changes in aluminum
Sheet metal forming processes involve large plastic deformation and changes in strain path. In this work, a
detailed analysis of a commercially pure aluminum sheet subjected to tension-tension sequences with pre-strain in the
rolling direction (RD) and reloads along different directions is presented, taking into consideration the mechanical behavior
and texture evolution. Two main hardening behavior tendencies are observed, depending whether the reloading direction
occurs for an angle smaller or larger than 45º.publishe
Fetal heart rate and fetal heart rate variability in Lipizzaner broodmares
Monitoring fetal heart rate (FHR) and fetal heart rate variability (FHRV) helps to understand and evaluate normal and pathological conditions in the foal. The aim of this study was to establish normal heart rate reference values for the ongoing equine pregnancy and to perform a heart rate variability (HRV) time-domain analysis in Lipizzaner mares. Seventeen middle- and late-term (days 121–333) pregnant Lipizzaner mares were examined using fetomaternal electrocardiography (ECG). The mean FHR (P = 0.004) and the standard deviation of FHR (P = 0.012) significantly decreased during the pregnancy. FHR ± SD values decreased from 115 ± 35 to 79 ± 9 bpm between months 5 and 11. Our data showed that HRV in the foal decreased as the pregnancy progressed, which is in contrast with the findings of earlier equine studies. The standard deviation of normal-normal intervals (SDNN) was higher (70 ± 25 to 166 ± 108 msec) than described previously. The root mean square of successive differences (RMSSD) decreased from 105 ± 69 to 77 ± 37 msec between the 5th and 11th month of gestation. Using telemetric ECG equipment, we could detect equine fetal heartbeat on day 121 for the first time. In addition, the large differences observed in the HR values of four mare-fetus pairs in four consecutive months support the assumption that there might be ‘high-HR’ and ‘low-HR’ fetuses in horses. It can be concluded that the analysis of FHR and FHRV is a promising tool for the assessment of fetal well-being but the applicability of these parameters in the clinical setting and in studs requires further investigation
Characterizations of quasitrivial symmetric nondecreasing associative operations
We provide a description of the class of n-ary operations on an arbitrary
chain that are quasitrivial, symmetric, nondecreasing, and associative. We also
prove that associativity can be replaced with bisymmetry in the definition of
this class. Finally we investigate the special situation where the chain is
finite
Development of a device compatible with universal testing machine to perform hole expansion and Erichsen cupping tests
The material characterization regarding sheet metal formability is usually assessed by
the forming limit curve (FLC). The FLC requires specialized and expensive equipment, several
samples with different geometries, and can be a very time-consuming procedure for data treatment.
Alternatively, the hole expansion test (HET) and the Erichsen Cupping Test (ECT) can be used
for routine evaluations of sheet metal mechanical behavior. These formability tests require fewer
quantities of material and easy specimen preparation with a fast analysis of results. The HET and ECT
procedures provide a proper evaluation of sheet material stretch-flangeability, formability, strength,
and ductility. In this work, we developed a low-cost mechanical device capable of performing the
HET and ECT tests using a universal testing machine. The equipment is designed to meet the test
parameters set by ISO 16630 (HET) and ISO 20482 (ECT) standards. In order to verify its functionality,
tests were carried out with the dual-phase steels DP600 and DP780. The corresponding values
determined for the hole expansion ratio and the Erichsen index provided reliable results in terms of
the accuracy and repeatability of the proposed testing device.publishe
The evaluation of laser weldability of the third-generation advanced high strength steel
To meet the demands of vehicular safety and greenhouse gas emission reduction,
the automotive industry is increasingly using advanced high strength steels (AHSS) in the production
of the components. With the development of the new generation of AHSS, it is essential to study
their behavior towards manufacturing processes used in the automotive industry. For this purpose,
the welding capability of newly developed third-generation Gen3 980T steel was investigated using the
Nd:YAG (Neodymium:Yittrium Aluminum Garnet) laser-welding with different parameter conditions.
The analysis was made by uniaxial tensile tests, micro-hardness, Scanning Electron Microscopy (SEM)
and X-Ray Diffraction (XRD). The criteria used to evaluate the quality of the weld were the distance
between the fracture and the weld bead and the surface finish. A relationship between the quality of
the weld and the energy density was observed, expressed by a partial penetration for values below
the optimal, and by irregularities in the weld bead and a high number of spatters for the values above
the optimal.publishe
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