/pdf/dual-function-thermoelastic-cloak-based-on-coordinate-1exwg1m5.pdf

Dual-function thermoelastic cloak based on coordinate transformation theory

Camouflaging the location of a sound source via topology-optimized source-shifter

For some products, such as radars, communication devices and key production line devices, the ability of continuous operating has an important impact on fulfilling tasks. As an important technical index, continuous operating time reflects the ability of products to operate continuously. But statistical model of continuous operating time has not yet been researched. In this paper, the definition of continuous operating time is given. Considering confidence level, an evaluation model of continuous operating time is proposed based on Minimum Order Statistic. Test plans are designed to verify continuous operating time with different consumer risks. Then a prediction model of continuous operating time is also constructed. A numerical example is introduced to illustrate the rationality and engineering applicability of the methods proposed in this paper.

An Evaluation Model for Continuous Operating Time Based on Minimum Order Statistic

Acoustic splitters and electromagnetic splitters can be applied in various fields (e.g., navigation and interference detection). However, there is still a lack of study of structures that can simultaneously split acoustic and electromagnetic beams. In this study, a novel, to the best of our knowledge, electromagnetic-acoustic splitter (EAS) based on copper plates is proposed, which can simultaneously produce identical beam-splitting effects for transverse magnetic (TM)-polarized electromagnetic and acoustic waves. Different from previous beam splitters, the beam splitting ratio of the proposed passive EAS can be simply tuned by changing the incident angle of the input beam, i.e., a tunable splitting ratio can be achieved without additional energy consumption. The simulated results verify that the proposed EAS can create two transmitted split beams with a tunable splitting ratio for both electromagnetic and acoustic waves. This may have applications in dual-field navigation/detection, which can provide additional information and higher accuracy compared with single-field navigation/detection. 

Electromagnetic-acoustic splitter with a tunable splitting ratio based on copper plates

Abstract In this chapter, we summarize this book and look to the future. In particular, we raise several key scientific questions for future directions of theoretical thermotics and potential applications in heat regulation. 

Summary and Outlook

Invisible coats inspired by metamaterials have been widely explored for different physical quantities and even with multifunctional response capabilities. In particular, a magnetic cloak has gained special attention for high practicability when compared with its electromagnetic counterparts. In this work, we report a bi-physical metamaterial invisible coating technique that could effectively hide underwater objects from being detected via both magnetic fields and acoustic waves. An ultra-thin coat could work for objects having irregular shapes like squares, greatly broadening potential practical applications. The bilayer magnetic cloaking technique is fully exploited to cast a spatially dependent permeability profile, which could quasi-statically balance out the diamagnetic response of irregular-shaped metals based on field “scattering” cancellation. Integrated with this magnetic cloak, an ultrathin acoustic metasurface made of periodic microbubbles is developed to achieve broadband acoustic absorption for acoustic stealth. This integrated magnetic-acoustic bi-physical conformal coat may lead to important applications not only for military purposes but also for civilian apparatus in shielding the field and wave disturbances, for example, in medical scanning.

Conformal metamaterial coats for underwater magnetic-acoustic bi-invisibility

Radars are the eye and ear of military equipment. The continuous working ability of a radar is to the key to guaranteeing combat effectiveness. This work proposes an assessment model of continuous working ability (CWA), based on minimal order statistics, to ensure the stability and reliability of a radar. The relationship between CWA and mean time between failure (MTBF) is analyzed to reduce the time and cost of reliability testing. Maintainability and testability are developed in expanded CWA models. Using the models, the CWA of a radar is verified considering its maintainability or testability. Finally, the relationship between CWA design, basic reliability, maintainability, and testability is examined. Methods for improvement of CWA are also introduced.

Kai Li

Papers

Conformal metamaterial coats for underwater magnetic-acoustic bi-invisibility

An Assessment Model for the Continuous Working Ability of Radars