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Multidimensional regulation of electromagnetic (EM) waves, especially for that joint amplitude-phase modulation occurring at different polarization channels, is pivotal for new-generation information processing and wireless communication. Helicity-multiplexed cascaded metadevices with low crosstalk and high efficiency are applied to complicated EM manipulation, but most are confined to half-space locked helicity states and modes. Herein, via introducing propagation phase with constructive interference into geometric phase, full-space helicity-dependent decoupling relationship between amplitude and phase engineering based on single-pixeled meta-particle is derived, and the implementing mechanism of nonsinterleaved completely helicity-modulated cascaded metasurface (NCHCM) in full space is further elucidated. Meanwhile, point-source diffraction method and iterative optimization algorithm are, respectively, developed to design the NCHCM, enabling precise holographic imaging performances. On this basis, two functional meta-devices assisted by energy-controllable NCHCM, including dual-channel helicity-selective complex-amplitude (CA) meta-hologram and quadruple-polarization-channel equal-amplitude phase-only meta-hologram, are demonstrated in the microwave region. The full-space completely helicity-modulated paradigm will boost the research of multidimension-controlled metasurfaces and might find multichannel delivery and information multiplexing applications in miniaturized and highly integrated systems.

Artificially elaborated metasurfaces with unparalleled manipulation of electromagnetic (EM) waves have sparked revolutionary upsurge in the microwave, terahertz, and even optics fields. Whether as the basic dimensions of EM waves, or modulated degrees of freedom (DOFs) for metasurfaces, independent customization of amplitude, phase, and polarization plays crucial roles in endowing kaleidoscopic wavefronts. However, the existing methods for simultaneous control suffer from insufficient efficiency, limited bandwidth, and transformed polarization, especially for transmissive geometry. Enlightened by twisted nematic liquid crystals, a highly efficient ultra-wideband transmissive metasurface integrating duplexing meta-particles that can enable efficient tailoring of the above three profiles. The designed planar device with subwavelength thickness is not only to implement high-performance transmission (amplitude limitation of near-unity) for linearly polarized (LP) waves along bi-directions, but can achieve complete phase modulation in ultra-wide band (fractal bandwidth of 124%). Divertingly, dual-twisted structure further eliminates crosstalk, maintaining interactive function for designated co-polarization. The concept and significance of it are validated via two proof-of-prototypes demonstrating functionalities composed of cascaded metasurfaces, which generate 2-D airy beam and complex-amplitude meta-hologram. Thus, the proposed strategy constructs a robust platform for advanced wavefronts manipulation within ultra-wide band and high efficiency, and might have remarkable potentials in beam forming, duplex communications, and information encryption.

Liquid crystals (LCs) are a kind of anisotropic materials with tunable dielectric properties in the microwave frequency band, which is of great significance for designing reconfigurable microwave devices such as beam-steering antennas, tunable phase shifters, or filters. Accurate characterization of the dielectric properties of LCs is crucial for designing and optimizing reconfigurable microwave components. In this article, a method for characterizing the dielectric properties of LCs is proposed based on epsilon-near-zero (ENZ) metamaterials. The measurement device is first designed using a waveguide-based ENZ structure. When LC-materials under tests (MUTs) are filled into the coupling tunnel, the strong electromagnetic intensity within ENZ metamaterials is fully utilized to sensitively detect the transmission response. In addition, biased circuits and preconditioned alignments are also designed and integrated to extract complex dielectric permittivities of anisotropic materials. Particularly, due to the metallic structure of the measurement device, a temperature control system consisting of a sensor and heating device can effectively and precisely control LC-MUTs’ temperature so that dielectric responses of LC-MUTs under different temperatures can be obtained. On this basis, according to the measured transmission parameters, the perturbation method is used to calculate complex dielectric permittivities of LC-MUTs. A prototype is fabricated and tested to verify the method. Complex dielectric permittivities of two LC-MUTs are extracted at 1.9 GHz, which verifies the effectiveness of the method. Note that the dielectric properties of a powder sample are also investigated using the same device, demonstrating the universality of this method. This work provides an alternative method for accurately measuring the complex permittivity of solid, liquid, and powder dielectric materials.

In this communication, we propose a block-and-guide method of enhancing isolation between Vivaldi antennas in the whole X-band using hyperbolic metasurface (HMS). The HMS consists of periodic parallel metallic strips patterned on a thin dielectric substrate. Due to its strong anisotropy, the HMS exhibits a passband for electromagnetic (EM) waves propagating along the strip direction while a stopband for EM waves propagating along the orthogonal direction. When the HMS is placed close to the opening end of the Vivaldi antenna, the broadside radiation of the antenna can be suppressed while the endfire radiation is almost unaffected, leading to enhanced isolation between adjacent antennas. Rather than adding auxiliaries in between antennas, the HMS can be readily integrated into the antenna radiator structure, which is more favorable for practical applications, especially in compact spaces. To verify this method, the prototype was fabricated and measured. Both simulated and measured results show that when the distance is $0.5\lambda _{0}$ ( $\lambda _{0}$ is the free-space wavelength of 10.0 GHz) between two Vivaldi antenna elements, the isolation can be increased by at least 10.0 dB in the whole X-band. This work provides an alternative to enhance isolation between wideband endfire antennas and may find applications in radar, wireless communication, and so on.

As protective apparatus, electromagnetic windows (EMWs) are usually realized utilizing dielectric materials with higher permittivity or larger thickness to perform good mechanical properties. However, due to impedance mismatch, higher insertion loss is inevitably created, especially at large incident angles. It is now still a great challenge to engineer EMWs with stable operating bands and a wide range of incident angles for both transverse electric (TE)- and transverse magnetic (TM)-polarizations. In this article, we propose a method to achieve such EMWs by the synergy of multimechanism resonances, which enables broadband transmissions of both TM- and TE-polarized waves in an ultrawide range of incident angles. Fano resonance is first introduced to expand the bandwidth for TE-polarization on the basis of thickness resonance. Drude resonances are then introduced to suppress adverse influences of the parasitic Lorentz resonance for TM-polarization, to maximize the shared transmission band for TM- and TE-polarizations. The ultrawide-angle broadband functionalities of this EMW are validated by experiments, which agree well with numerical simulations. This work provides an efficient route to realize practical high-performance EMWs, under sufficient consideration of available materials, structures, and fabrication techniques, which may find wide applications in radar, communication, and imaging systems.

The continuous increase in communication capacity is accompanied by an increase in transmission frequency, which creates new demands on the transmission efficiency in modern. Signal relay transmission can increase the transmission distance, however, conventional repeaters relay the signal in a specified direction, which is difficult to accommodate communication when a receiving device suddenly appears around the repeater. In this work, we propose a new signal transmission repeater, which is implemented by an adaptively reconfigurable multi-beam reflective metasurface based on multispectral detection. The reconfigurable metasurface with varactor diodes is designed and the mapping of phase profiles to voltages is established by polynomial fitting method. Visual, laser, infrared and ultrasonic detectors are used to detect targets in different scenarios. Thus, the detection information is fed back to the reconfigurable metasurface for adaptively multi-beam switching. As verification, the adaptive metasurface repeater was fabricated and measured to verify our design. All the results exhibit consistency with theoretical design. Importantly, this work paves a new way to intelligent metasurfaces and may find applications in intelligent communications, smart home, etc.

A simple physics-based method for estimating optical turbulence (Cn2) within the surface layer over snow and ice is proposed, using the Tatarski equation with an improved outer scale model. This improved outer scale model mainly requires the calculation of the wind shear and temperature gradients. Based on the measurements from a mobile polar atmospheric parameter measurement system at the Antarctic Taishan Station in 2014, Cn2 was estimated using two methods: the Tatarski equation and the Monin–Obukhov similarity (MOS) theory. Compared with 16 days of measurements from a micro-thermometer, the correlation coefficient of log_10(Cn2) estimated by the Tatarski equation is 0.72, which is a slightly more accurate Cn2 variation in trend and magnitude than the MOS theory. The results suggest that this simple method has potential value for the forecasting applications of optical turbulence.

An optical turbulence ($C_n^2$) was found to be concentrated predominantly in the thin surface layer (SL) above the Antarctic Plateau. We present an estimation of the behavior of the SL $C_n^2$ during the summer time over the entire Antarctic Plateau, using the polar-optimized version of the Weather Research and Forecast model (Polar WRF) coupled with the Monin–Obukhov similarity theory. The results show that the $C_n^2$ is affected by the sunlight direction and terrain height. The $C_n^2$ minimum occurs sometime around the morning and evening transitions, when the condition of neutral stability is achieved inside the SL. These $C_n^2$ minima may be attributed to the relatively weaker thermal convection resulting from a small temperature difference. The simulated $C_n^2$ data coincide well with the measurements taken at the Antarctic Taishan Station using a micro-thermometer and sonic anemometer; the data are also in agreement with the seeing values obtained from a differential image motion monitor. In addition, the Polar WRF captured the $C_n^2$ minimum more precisely compared to the standard WRF.

Flight scheduling is the foundation and core of all the activities of airports and airlines. This paper analyses the problem of flight landing scheduling with multi-runway and establishes mathematical model. The aim is to determine the aircraft landing sequence and the landing time with the objective to minimise the landing time deviation cost. A new heuristic approach called cost decision algorithm (CDA) is present to solve the problem. This method selects the runway and decides the landing time by comparing the costs. With a series of experiments of different scale data, the mathematical model is solved by CDA and other algorithm. The computational results demonstrated the feasibility and superiority of the proposed algorithm by comparing with other algorithms in solutions and running time.

Grouping of jobs from the same family on bottleneck resource is significant to reduce setup time of jobs. But, the grouping may result in delay of jobs. How to balance the contradiction between utilisation of bottleneck resource and delivery time is a great challenge in production scheduling. This paper considers a single machine scheduling problem in which each job to be scheduled belongs to a family and family setup times exist. This paper is aimed to identify a schedule of families of jobs to minimise total tardiness with respect to the given due dates of the jobs. A mathematical model is formulated for this problem and a heuristic solution approach is presented. Computational experiments show that the proposed heuristic algorithm performs better both in terms of solution quality and computational time.

Achieving the conversion from surface waves (SWs) to propagating waves has captivated long-standing interest, and various ingenious metasurfaces benefiting from the powerful control capability for electromagnetic waves are able to realize efficient SWs directional radiation. Nevertheless, most existing schemes still suffer from the bottlenecks of single radiation channel, uncontrollable radiation intensity, and immutable radiation pattern, which immensely hinder their practical application in high-integration intelligent devices. Herein, a series of appealing strategies are proposed to achieve the dual-channel SWs directional radiation with customizable radiation intensity and switchable radiation pattern. The dual-channel SWs radiation metadevice based on the phase modulation metasurface is designed to directionally radiate SWs in left-handed circular polarized channel and right-handed circular polarized channel and possesses the broadband frequency scanning characteristic. More strikingly, the intensity-customizable dual-channel SWs radiation metadevice loaded with lumped resistors can control the realized gain of two circular polarized radiation beams, and the pattern-switchable dual-channel SWs radiation metadevice loaded with PIN diodes can dynamically adjust the radiation direction of the radiation beams. Numerous simulations and experiments of the proof-of-concept prototypes with modular design corroborate the theoretical predictions. Our methodology shows unprecedented flexibility in regulating SWs directional radiation and has enormous potential in engineering applications.

The power of controlling objects with mind has captivated a popular fascination to human beings. One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces (PM), whose functions or operating modes can be switched or customized via on-site programming or pre-defined software. Nevertheless, most of existing PMs are wire-connected to users, manually-controlled and not real-time. Here, we propose the concept of remotely mind-controlled metasurface (RMCM) via brainwaves. Rather than DC voltage from power supply or AC voltages from signal generators, the metasurface is controlled by brainwaves collected in real time and transmitted wirelessly from the user. As an example, we demonstrated a RMCM whose scattering pattern can be altered dynamically according to the user’s brain waves via Bluetooth. The attention intensity information is extracted as the control signal and a mapping between attention intensity and scattering pattern of the metasurface is established. With such a framework, we experimentally demonstrated and verified a prototype of such metasurface system which can be remotely controlled by the user to modify its scattering pattern. This work paves a new way to intelligent metasurfaces and may find applications in health monitoring, 5G/6G communications, smart sensors, etc.

This study investigated the impact of incretin on early-phase insulin secretion and glucose excursion. The normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) groups included 16, 8, and 19 subjects, respectively. Subjects underwent continuous glucose monitoring for 3 days, followed by an oral glucose tolerance test. Plasma glucose, insulin, glucagon, total glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-l (GLP-1) levels were measured at 30-min increments for 2 h after glucose intake. Differences with P< 0.05 were considered statistically significant. The area under the curve (AUC) of total GIP (120-min GIP-AUC) of the T2DM group was significantly lower than those of the NGT and IGT groups. The 120-min GLP-1-AUC of the NGT group was significantly larger than those of the T2DM and IGT groups. The early-phase insulin secretion index (ΔI30/ΔG30) of the T2DM group was significantly lower than those of the NGT and IGT groups. Mean amplitudes of glycemic excursions (MAGEs) went in the order of NGT < IGT < T2DM (P< 0.01, IGT vs. NGT; P< 0.001, T2DM vs. IGT). The 120-min GIP-AUC was negatively correlated with MAGE (r= −0.464), but uncorrelated with ΔI30/ΔG30. The 120-min GLP-1-AUC was positively correlated with ΔI30/ΔG30 (r= 0.580), but negatively correlated with MAGE (r= −0.606). Incretin may ameliorate glucose excursions, and GLP-1 may exert them by promoting early-phase insulin secretion. No correlation was observed between GIP secretion and early-phase insulin secretion.

Metasurfaces with simultaneously and independently controllable amplitude and phase have provided a higher degree of freedom in manipulating electromagnetic (EM) waves. Compared with phase- or amplitude-only modulation, the capability of simultaneously controlling the phase and amplitude of EM waves can enable holography with a higher resolution. However, this drastically increases the design complexity of holographic metasurfaces, and the design process is usually quite time-consuming. In this paper, we propose an inverse design of meta-atoms that can simultaneously and independently tailor the phase and amplitude of transmitted waves using customized deep ResNet while eliminating the coupling of parameters. To demonstrate the design method, two holographic metasurfaces were designed using the trained network without the need for parameter sweeping, which will significantly enhance design efficiency. Prototypes were fabricated and measured. Both the simulated and measured results show that high-resolution holography is obtained, which sufficiently verifies the reliability of the design method. Our work paves the way for the intelligent design of metasurfaces and can also be applied to the design of other artificial materials or surfaces.

This study proposes a method of designing a shared-aperture metasurface that can realize different functionalities in a dual-spectrum for circularly polarized (CP) waves. Instead of depending on helicity, different functionalities are realized using bi-layer unit cells displaying diverse phase profiles in different bands for CP waves with the same helicity. As a proof-of-concept, we designed a shared-aperture metasurface to achieve deflected beam splitting and focusing for left-handed CP waves. The simulated and measured results are analyzed to validate the design. This work provides an alternative strategy for achieving multi-functionality and may find applications in radar and communication systems.