2,314 research outputs found
Elasto-Plastic Behavior of Aluminum Foams Subjected to Compression Loading
The non-linear behavior of uniform-size cellular foams made of aluminum is investigated when subjected to compressive loads while comparing numerical results obtained in the Finite Element Method software (FEM) ANSYS workbench and ANSYS Mechanical APDL (ANSYS Parametric Design Language). The numerical model is built on AUTODESK INVENTOR, being imported into ANSYS and solved by the Newton – Raphson iterative method. The most similar conditions were used in ANSYS mechanical and ANSYS workbench, as possible. The obtained numerical results and the differences between the two programs are presented and discussed.Досліджено нелінійну поведінку однорідних кліткоподібних пін, зроблених з алюмінію і підданих стиску. Порівнено числові результати, одержані двома програмними пакетами: Finite Element Method software (FEM) ANSYS workbench і ANSYS Mechanical APDL (ANSYS Parametric Design Language). Числову модель побудовано в AUTODESK INVENTOR і надалі її імпортовано в ANSYS і розв'язано за допомогою методу Ньютона - Рафсона. Використано якомога ближчі умови у вказаних пакетах. Представлено і прокоментовано одержані числові результати і спостережені відмінності між двома пакетами
Millimeter-scale unipolar transport in high sensitivity organic-inorganic semiconductor X-Ray detectors
Hybrid inorganic-in-organic semiconductors are an attractive class of materials for optoelectronic applications. Traditionally, the thicknesses of organic semiconductors are kept below 1 micron due to poor charge transport in such systems. However, recent work suggests that charge carriers in such organic semiconductors can be transported over centimeter length scales opposing this view. In this work, a unipolar X-ray photoconductor based on a bulk heterojunction architecture, consisting of poly(3-hexylthiophene), a C70 derivative and high atomic number bismuth oxide nanoparticles operating in the 0.1 – 1 mm thickness regime is demonstrated, having a high sensitivity of ~160 µCmGy-1cm-3. The high performance enabled by hole drift lengths approaching a millimeter facilitates a device architecture allowing a high fraction of the incident X-rays to be attenuated. An X-ray imager is demonstrated with sufficient resolution for security applications such as portable baggage screening at border crossings and public events and scalable medical applications
The emerging zika virus epidemic in the Americas: Research priorities
On February 1, 2016, the World Health Organization
declared a “public health emergency of international
concern” regarding neurological disorders associated
with the rapid emergence of Zika virus (ZIKV) in the
Americas. Since being detected in Brazil in early 2015,
ZIKV has spread extensively, with most countries in
Latin America and the Caribbean now reporting local
transmission of the virus. An association between congenital
ZIKV infection and birth defects, most prominently
microcephaly, has prompted intense concern
among health officials and the public
Multi-score Learning for Affect Recognition: the Case of Body Postures
An important challenge in building automatic affective state
recognition systems is establishing the ground truth. When the groundtruth
is not available, observers are often used to label training and testing
sets. Unfortunately, inter-rater reliability between observers tends to
vary from fair to moderate when dealing with naturalistic expressions.
Nevertheless, the most common approach used is to label each expression
with the most frequent label assigned by the observers to that expression.
In this paper, we propose a general pattern recognition framework
that takes into account the variability between observers for automatic
affect recognition. This leads to what we term a multi-score learning
problem in which a single expression is associated with multiple values
representing the scores of each available emotion label. We also propose
several performance measurements and pattern recognition methods for
this framework, and report the experimental results obtained when testing
and comparing these methods on two affective posture datasets
Jatrophane and lathyrane diterpenoids from Euphorbia hyberna L
A new diterpene tetraester, from the jatrophane family, and two new diterpene triesters, with a lathyrane skeleton, have been
isolated from the chloroform extract of the roots of Euphorbia hyberna L. The structures of these compounds have been established
by spectroscopic methods, including 2D NMR experiments.info:eu-repo/semantics/publishedVersio
Radioactivity Backgrounds in ZEPLIN-III
We examine electron and nuclear recoil backgrounds from radioactivity in the ZEPLIN-III dark matter experiment at Boulby. The rate of low-energy electron recoils in the liquid xenon WIMP target is 0.750.05 events/kg/day/keV, which represents a 20-fold improvement over the rate observed during the first science run. Energy and spatial distributions agree with those predicted by component-level Monte Carlo simulations propagating the effects of the radiological contamination measured for materials employed in the experiment. Neutron elastic scattering is predicted to yield 3.050.5 nuclear recoils with energy 5-50 keV per year, which translates to an expectation of 0.4 events in a 1-year dataset in anti-coincidence with the veto detector for realistic signal acceptance. Less obvious background sources are discussed, especially in the context of future experiments. These include contamination of scintillation pulses with Cherenkov light from Compton electrons and from activity internal to photomultipliers, which can increase the size and lower the apparent time constant of the scintillation response. Another challenge is posed by multiple-scatter -rays with one or more vertices in regions that yield no ionisation. If the discrimination power achieved in the first run can be replicated, ZEPLIN-III should reach a sensitivity of pbyear to the scalar WIMP-nucleon elastic cross-section, as originally conceived.Peer Reviewe
Emergence of Anti-Cancer Drug Resistance: Exploring the Importance of the Microenvironmental Niche via a Spatial Model
Practically, all chemotherapeutic agents lead to drug resistance. Clinically,
it is a challenge to determine whether resistance arises prior to, or as a
result of, cancer therapy. Further, a number of different intracellular and
microenvironmental factors have been correlated with the emergence of drug
resistance. With the goal of better understanding drug resistance and its
connection with the tumor microenvironment, we have developed a hybrid
discrete-continuous mathematical model. In this model, cancer cells described
through a particle-spring approach respond to dynamically changing oxygen and
DNA damaging drug concentrations described through partial differential
equations. We thoroughly explored the behavior of our self-calibrated model
under the following common conditions: a fixed layout of the vasculature, an
identical initial configuration of cancer cells, the same mechanism of drug
action, and one mechanism of cellular response to the drug. We considered one
set of simulations in which drug resistance existed prior to the start of
treatment, and another set in which drug resistance is acquired in response to
treatment. This allows us to compare how both kinds of resistance influence the
spatial and temporal dynamics of the developing tumor, and its clonal
diversity. We show that both pre-existing and acquired resistance can give rise
to three biologically distinct parameter regimes: successful tumor eradication,
reduced effectiveness of drug during the course of treatment (resistance), and
complete treatment failure
Stress response inside perturbed particle assemblies
The effect of structural disorder on the stress response inside three
dimensional particle assemblies is studied using computer simulations of
frictionless sphere packings. Upon applying a localised, perturbative force
within the packings, the resulting {\it Green's} function response is mapped
inside the different assemblies, thus providing an explicit view as to how the
imposed perturbation is transmitted through the packing. In weakly disordered
arrays, the resulting transmission of forces is of the double-peak variety, but
with peak widths scaling linearly with distance from the source of the
perturbation. This behaviour is consistent with an anisotropic elasticity
response profile. Increasing the disorder distorts the response function until
a single-peak response is obtained for fully disordered packings consistent
with an isotropic description.Comment: 8 pages, 7 figure captions To appear in Granular Matte
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