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We experimentally demonstrate the broadband and highly efficient inversion of the rotation direction of the terahertz circular polarization achieved by a dynamic metasurface with vanadium dioxide ( VO 2 ). This metasurface converts linear polarization into circular polarization. The rotational direction of the output circular polarization can be reversed based on the VO 2 phase transition. The VO 2 state can be dynamically switched by injecting direct current into an on-chip circuit. To improve the terahertz-wave utilization efficiency, the metasurface is operated at an incident angle of 45°, thereby eliminating the beam splitter typically used to separate the outgoing wave from the incident wave at normal incidence. To achieve broadband operation, we employ a dispersion-cancelation strategy that cancels the dispersive phase responses between orthogonal linear polarizations. This strategy was previously developed for static metasurfaces; we have applied it to the design of dynamic metasurfaces. At a center frequency of 0.99 THz, the experimental evaluation demonstrated helicity switching with conversion efficiencies of 92% and 87% for the insulating and metallic states of VO 2 , respectively. Dispersion cancelation is simultaneously achieved for the insulating and metallic states of VO 2 , resulting in a relative bandwidth of 0.26, which is 3.2 times broader than that of a previously developed efficient dynamic metasurface. [ABSTRACT FROM AUTHOR]

Although performance-based design, procurement, and construction management are now spreading rapidly in the building construction field, full-fledged study of the method for public works has barely begun. At this time, therefore, the concept expressed by the term 'performance-based design' (which in this article, for simplicity, will include procurement and construction management) varies from person to person. This article is a basic study of the concepts of performance-based standards, performance-based standardization, and performance-based ordering, which are all necessary to introduce the performance-based design approach into the civil engineering field. It is proposed that performance-based design be defined in terms of two conditions: attainment level of objective of use, and degree of freedom. The article introduces the bottom-up and top-down methods as basic performance standardization methodologies. DOI: 10.1061/(ASCE)1052-3928(2002)128:1(30) CE Database keywords: Design; Civil engineering; Performance standards.

Presents a study on the concepts of performance-based standards, performance standardization and performance-based ordering in civil engineering. Concept of performance-based design; Methods of introducing performance-based design; Details of practical performance-based standardization; Conclusions.