2,258 research outputs found
Gradient Hard Thresholding Pursuit for Sparsity-Constrained Optimization
Hard Thresholding Pursuit (HTP) is an iterative greedy selection procedure
for finding sparse solutions of underdetermined linear systems. This method has
been shown to have strong theoretical guarantee and impressive numerical
performance. In this paper, we generalize HTP from compressive sensing to a
generic problem setup of sparsity-constrained convex optimization. The proposed
algorithm iterates between a standard gradient descent step and a hard
thresholding step with or without debiasing. We prove that our method enjoys
the strong guarantees analogous to HTP in terms of rate of convergence and
parameter estimation accuracy. Numerical evidences show that our method is
superior to the state-of-the-art greedy selection methods in sparse logistic
regression and sparse precision matrix estimation tasks
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
Electrochemical codeposition of nickel oxide and polyaniline
Nickel oxide (NiOx) and polyaniline (PAni) were
electrocodeposited from NiSO4 and aniline through cyclic
voltammetric scans to afford PAni–NiOx composite film at
controlled pH environment. The electrochemical activities of
the film were investigated by cyclic voltammetry in 0.1 M
NaOH and 0.1 M H2SO4, respectively. Typical redox couples
of PAni in 0.1 M H2SO4 appeared at approximately 0.2 and
0.4 V vs. saturated calomel electrode (SCE); Ni(II)/Ni(III)
redox couple was observed at approximately 0.4 V vs. SCE in
0.1 M NaOH. The morphologies and elemental components
of the films were inspected by scanning electron microscopy
and energy dispersive X-ray diffraction. The stability of nickel
oxide in the films was found to be enhanced against acidic
environments. Electrochemical catalytic behavior of NiOx
within the composite film was conserved and demonstrated
by catalytic oxidation of methanol and ethanol
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