Newsvendor Conditional Value-at-Risk Minimisation with a Non-Parametric Approach

In the classical Newsvendor problem, one must determine the order quantity that maximises the expected profit. Some recent works have proposed an alternative approach, in which the goal is to minimise the conditional value-at-risk (CVaR), a very popular risk measure in financial risk management. Unfortunately, CVaR estimation involves considering observations with extreme values, which poses problems for both parametric and non-parametric methods. Indeed, parametric methods often underestimate the downside risk, which leads to significant losses in extreme cases. The existing non-parametric methods, on the other hand, are extremely computationally expensive for large instances. In this paper, we propose an alternative non-parametric approach to CVaR minimisation that uses only a small proportion of the data. Using both simulation and real-life case studies, we show that the proposed method can be very useful in practice, allowing the decision makers to suffer less downside loss in extreme cases while requiring reasonable computing effort

Plasmonics for surface-enhanced Raman scattering: from classical to quantum

Metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies are termed "plasmonic optical antennas". These structures enhance light-matter interactions in an efficient manner, enabling unique linear and nonlinear optical applications. One such application is surface-enhanced Raman scattering (SERS), which employs plasmonic antennas to enhance Raman cross-section of molecules by orders of magnitude. SERS has attracted a significant amount of research attention since it enables molecules to be identified through their characteristic vibrational spectra, even at the single molecule level.Engineering and Applied Science

Dynamical commensuration effect in a two-dimensional Yukawa solid modulated by periodic substrates

Transverse depinning dynamics of a periodic-square-substrate modulated two-dimensional dusty plasma solid driven by a constant force in the longitudinal direction are investigated using Langevin dynamical simulations. During the increase of the commensuration ratio (the number ratio of particles to substrate potential wells), the nonmonotonic variation trend of the critical transverse depinning force is observed. It is found that the local maxima and minima of the critical transverse depinning force just correspond to the dynamical commensurate and incommensurate conditions, respectively. The dynamical commensurate effect is also clearly exhibited from the stable one-dimensional channel particle trajectories and the highly ordered structure, however, both the particle trajectories and the structure are more disordered under the incommensurate conditions. The nonmonotonic variation of the critical transverse depinning force is attributed to the stability of the lattice structure under various commensuration ratios.Comment: 9 pages, 4 postscript figure

Point Defects in Two-Dimensional RuCl3

Defects are crucial in determining a variety of material properties especially in low dimensions. In this work, we study point defects in monolayer alpha-phase Ruthenium (III) chloride (alpha-RuCl3), a promising candidate to realize quantum spin liquid with nearly degenerate magnetic states. Our first-principles simulations reveal that Cl vacancies, Ru vacancies, and oxygen substitutional defects are the most energetically stable point defects. Besides, these point defects break the magnetic degeneracy: Cl vacancies and oxygen substitutional defects energetically favor the zigzag-antiferromagnetic configuration while Ru vacancies favor the ferromagnetic configuration, shedding light on understanding the observed magnetic structures and further defect engineering of magnetism in monolayer {\alpha}-RuCl3. We further calculated their electronic structures and optical absorption spectra. The polarization symmetry of optical responses provides a convenient signature to identify the point defect types and long-range magnetic orders.Comment: 28 pages, 8 figure