1,010 research outputs found
Finite Element Analysis of Low-Velocity Impact Damage on Stiffened Composite Panels
To understand the factors which affect impact damage on composite structures, particularly the effects of impact position and ribs. In this paper, a finite element model (FEM) of low-velocity impact damage on the composite structure was established via the nonlinear finite element method, combined with the user-defined materials subroutine (VUMAT) of the ABAQUS software. The structural elements chosen for the investigation comprised a series of stiffened composite panels, representative of real aircraft structure. By impacting the panels at different positions relative to the ribs, the effect of relative position of ribs was found out. Then the simulation results and the experiments data were compared. Finally, the factors which affect impact damage on the structures were discussed. The paper was helpful for the design of stiffened composite structures
High-temperature cluster expansion for classical and quantum spin lattice systems with multi-body interactions
We develop a novel cluster expansion for finite-spin lattice systems subject
to multi-body quantum -- and, in particular, classical -- interactions. Our
approach is based on the use of ``decoupling parameters", advocated by Park
[34], which relates partition functions with successive additional interaction
terms. Our treatment, however, leads to an explicit expansion in a
-dependent effective fugacity that permits an explicit evaluation of
free energy and correlation functions at small . To determine its
convergence region we adopt a relatively recent cluster summation scheme that
replaces the traditional use of Kikwood-Salzburg-like integral equations by
more precise sums in terms of particular tree-diagrams [2]. As an application
we show that our lower bound of the radius of -analyticity is larger
than Park's for quantum systems two-body interactions
Rates of Approximation by ReLU Shallow Neural Networks
Neural networks activated by the rectified linear unit (ReLU) play a central
role in the recent development of deep learning. The topic of approximating
functions from H\"older spaces by these networks is crucial for understanding
the efficiency of the induced learning algorithms. Although the topic has been
well investigated in the setting of deep neural networks with many layers of
hidden neurons, it is still open for shallow networks having only one hidden
layer. In this paper, we provide rates of uniform approximation by these
networks. We show that ReLU shallow neural networks with hidden neurons can
uniformly approximate functions from the H\"older space
with rates when
. Such rates are very close to the optimal one
in the sense that is close to , when the dimension is
large
The Role of Human Capital: Evidence From Patent Generation
Firms exhibit persistence in innovation output. This paper focuses on the role played by individual inventors. Compared to firm organizational capital, human capital embedded in inventors explains a majority of the variation in innovation performance but much less in innovation style. Inventors contribute more when they are better networked, in firms with higher inventor mobility, and in industries in which innovation is more difficult. Additional tests suggest that our main findings are unlikely driven by inventors’ endogenous moving. This paper highlights the importance of human capital in enhancing firm innovation and sheds new light on the theory of the firm
Free energy expansions for renormalized systems for colloids
We consider a binary system of small and large spheres of finite size in a
continuous medium interacting via a non-negative potential. We work in the
canonical ensemble and compute upper and lower bound for the free energy at
finite and infinite volume by first integrating over the small spheres and then
treating the effective system of the large ones which now interact via a
multi-body potential. By exploiting the underlying structure of the original
binary system we prove the convergence of the cluster expansion for the latter
system and obtain a sufficient condition which involves the surface of the
large spheres rather than their volume (as it would have been the case in a
direct application of existing methods directly to the binary system). Our
result is valid for the particular case of hard spheres (colloids) for which we
rigorously treat the depletion interaction
Do Individuals or Firms Matter More? The Case of Patent Generation
This paper studies the relative importance of individual inventors’ human capital and firms’ organizational capital in promoting a firm’s innovation output. We decompose the variation in innovation output into inventor- and firm-specific components. Inventors’ human capital is about 13 times as important as firms’ organizational capital in explaining a firm’s innovation performance in terms of patent counts and citations, while inventors’ human capital is only about the same as important when explaining the firm’s innovation styles in terms of patent exploratory and exploitive scores. In the cross section, inventors contribute more to innovation output when they are better networked, in firms with higher inventor mobility, in industries in which innovation is more difficult to achieve, and in publicly traded firms. Additional tests suggest that our main findings continue to hold after accounting for inventors’ endogenous moving. This paper highlights the importance of individual inventors in enhancing firm innovation and sheds new light on the theory of the firm
Harmonics of Parton Saturation in Lepton-Jet Correlations at the EIC
Parton saturation is one of the most intriguing phenomena in the high energy
nuclear physics research frontier, especially in the upcoming era of the
Electron-Ion Collider (EIC). The lepton-jet correlation in deep inelastic
scattering provides us with a new gateway to the parton saturation at the EIC.
In particular, we demonstrate that azimuthal angle anisotropies of the
lepton-jet correlation are sensitive to the strength of the saturation momentum
in the EIC kinematic region. In contrast to the predictions based on the
collinear framework calculation, significant nuclear modification of the
anisotropies is observed when we compare the saturation physics results in e +
p and e + Au scatterings. By measuring these harmonic coefficients at the EIC,
one can conduct quantitative analysis in different collisional systems and
unveil compelling evidence for saturation effects.Comment: 7 pages, 3 figure
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