Counting derangements with signed right-to-left minima and excedances

Recently Alexandersson and Getachew proved some multivariate generalizations of a formula for enumerating signed excedances in derangements. In this paper we first relate their work to a recent continued fraction for permutations and confirm some of their observations. Our second main result is two refinements of their multivariate identities, which clearly explain the meaning of each term in their main formulas. We also explore some similar formulas for permutations of type B.Comment: Advances in Applied Mathematics 152, 10259

High-dimensional quantum key distribution based on mutually partially unbiased bases

We propose a practical high-dimensional quantum key distribution protocol based on mutually partially unbiased bases utilizing transverse modes of light. In contrast to conventional protocols using mutually unbiased bases, our protocol uses Laguerre-Gaussian and Hermite-Gaussian modes of the same mode order as two mutually partially unbiased bases for encoding, which leads to a scheme free from mode-dependent diffraction in long-distance channels. Since only linear and passive optical elements are needed, our experimental implementation significantly simplifies qudit generation and state measurement. Since this protocol differs from conventional protocols using mutually unbiased bases, we provide a security analysis of our protocol

Design of a Bidirectional DC/DC Converter for Energy Storage in Electric Aircraft

High-density power conversion and energy storage solutions were and are being explored for use in Electric Aircraft (EA). A superconducting magnetic energy storage (SMES) system is a promising candidate due to its fast response and ability to satisfy large pulse loads as is expected from EA. For the SMES, Dual Active Bridge (DAB) converters can offer high-density power conversion and provide galvanic isolation. This paper proposes a design methodology for a bidirectional DC/DC converter using DAB converter and a MOSFET-based chopper to interface SMES. This paper includes analysis, performance prediction, and needs for implementation in EA. The DAB/SMES system has been successfully designed, analyzed, and is being optimized for application in EA

Design of a Bidirectional DC/DC Converter for Energy Storage in Electric Aircraft

High-density power conversion and energy storage solutions were and are being explored for use in Electric Aircraft (EA). A superconducting magnetic energy storage (SMES) system is a promising candidate due to its fast response and ability to satisfy large pulse loads as is expected from EA. For the SMES, Dual Active Bridge (DAB) converters can offer high-density power conversion and provide galvanic isolation. This paper proposes a design methodology for a bidirectional DC/DC converter using DAB converter and a MOSFET-based chopper to interface SMES. This paper includes analysis, performance prediction, and needs for implementation in EA. The DAB/SMES system has been successfully designed, analyzed, and is being optimized for application in EA

Two-dimensional to three-dimensional structural transition of gold cluster Au 10 during soft landing on TiO 2 surface and its effect on CO oxidation

We investigate the possible structural transition of a planar Au10 cluster during its soft landing on a TiO2 (110) surface with or with no oxygen defects. The collision between the gold cluster and the oxide surface is simulated using the Car–Parrinello quantum molecular dynamics method. Both high-speed and low-speed conditions typically implemented in soft-landing experiments are simulated. It is found that under a high-speed condition, the gold cluster Au10 can undergo a sequence of structural transitions after colliding with a defect-free TiO2 (110) surface. When the TiO2 (110) surface possesses oxygen vacancies, however, chemical bonds can form between gold and Ti atoms if gold atoms contact directly with the vacancies. As a consequence, one oxygen vacancy is capable of trapping one Au atom, and thus can split the Au10 into two parts while bouncing back from the surface. In addition, we study reaction pathways for the CO oxidation based on three isomer structures of Au10 observed in the soft-landing simulation: (1) the precollision two-dimensional structure, (2) a postcollision three-dimensional (3D) structure, and (3) an intermediate (transient) 3D structure that appeared in the midst of the collision. This study allows us to examine the structure-activity relationship using the Au10 as a prototype model catalyst