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Risk factors and prognosis of acute respiratory distress syndrome (ARDS) following abdominal surgery were investigated. Five hundred and thirty-two patients who underwent abdominal surgery in Dongyang People's Hospital from February 2006 to May 2016 were enrolled. Among them, 113 patients had ARDS after surgery and 45 patients died. Those patients were included in observation group. The 419 patients who did not develop ARDS were included in control group, and 11 patients died. General data of patients were statistically analyzed, and the factors with statistical significance were subjected to multivariate logistic regression analysis to analyze the risk factors of ARDS. There was a significant difference in age, infection, trauma-to-surgery time, and prognosis between the two groups (P

A tunable spoof surface plasmons antenna using sinusoidally modulated corrugated reactance surface based on a bulleye structure is proposed in this paper. The designed antenna is made of concentric metallic grooves etched on a metal plate, the depth of which is of sinusoidal periodic variation in the radial direction. This makes it possible that highly confined spoof surface plasmons along corrugated surface can be converted to radiation modes. The proposed bulleye antenna can work from 25.8 to 33 GHz and a bandwidth of 7.2 GHz and its main lobe can be directed at 30∘ from the vertical direction at 30 GHz. This antenna has a maximum gain of 15 dB and its main lobe can scan from 14∘ to 58∘ by tuning the frequency from 28 to 32 GHz.

A design method of embedded SIW slot array antenna is proposed in this paper. It regards the metal groove walls as waveguide narrow-walls, instead of the traditional metallized through holes. So that it is easier to control the resonant parameters of slots during design process. The radiation power of a taper distribution in slot array is designed, corresponding to the geometric parameters database of SIW slot. Then this paper completed the electromagnetic simulation of SIW slot array within $32 \times 36$ elements. All pattern peak value in operating frequency band is over 37 dBi, the sidelobe level is below −19.2 dB, and the half power beam width is within 2.4 °. It verifies the feasibility of design method.

In this work, a low-pass plasmonic filter based on spoof surface plasmon polaritons (SSPPs) is reported by etching the two grounds of coplanar waveguide with periodic grooves. The cutoff frequency of the filter coincides with the asymptotic frequency of the SSPPs that are supported by the periodic grooves, which can be tuned by the depth of the grooves at will. In addition, a T-shaped groove is designed to increase the equivalent depth of the groove so as to realize the miniaturization of the proposed filter by decreasing the equivalent cutoff frequency of the SSPPs. Measured S-parameters of the two proposed low-pass plasmonic filters agree well with the simulated ones, which validates our ideas and designs. This simple low-pass plasmonic filter can find potential applications in plasmonic circuits and systems.

In this work, we report a fishbone-like high-efficiency low-pass plasmonic filter based on a double-layered conformal surface plasmon waveguide (CSPW) which consists of double-layered symmetrical metal gratings (SMGs) of fishbone shape. Efficient mode conversion between the quasi-transverse electromagnetic (TEM) waves in the microstrip line and the conformal surface plasmons (CSPs) on the double-layered CSPW is realized by using gradient double-layered SMGs and impedance matching technique. Experimental results of the transmission and reflection coefficients of the straight sample show excellent loss-pass performance and agree well with the numerical simulations. The curved samples exhibit low radiation loss when the double-layered CSPW is conformal or even bent thanks to the high confinement of CSPs. The proposed structure can find potential applications in integrating conventional circuits with CSPs devices at microwave and terahertz frequencies.

A series of phosphosilicate phosphors Sr 8 La 2 (PO 4 ) 3.5 (SiO 4 ) 2 (BO 4 ) 0.5 BO 2 : Ce 3+ , Tb 3+ are synthesized by solid-state reaction for the first time. The XRD Rietveld refinement presents that the compound crystallizes in a trigonal crystal system with space group P 3 ¯ (No. 147). Under the excitation of 340 nm, commonly blue and yellowish green emissions from Ce 3+ and Tb 3+ are detected and can generate the color-tunable light with chromaticity coordinates from (0.188, 0.095) to (0.351, 0.517) by changing the ratio of Ce 3+ /Tb 3+ . By the photoluminescence spectra, decay times and energy transfer efficiency, the mechanism of energy transfer between Ce 3+ and Tb 3+ has been carefully investigated. With the increase of temperature, the Ce 3+ or Tb 3+ single doped sample shows an excellent thermal property, but when the Ce 3+ and Tb 3+ are co-doped into the host, the thermal property of sample seriously degenerates. This result indicates that the change of temperature can affect the energy transfer between Ce 3+ and Tb 3+ strongly and based on the configurational coordinate diagram, this phenomenon is explained reasonably.

The paper proposes a simple band stop frequency selective surface (FSS) design method based on spoof surface plasmon polaritons (spoof-SPPs). The novel FSS design is obtained by combing three-dimension (3-D) FSS and ultra-thin periodic corrugated metallic strip which supports spoof-SPPs. By placing electric-LC (ELC) resonators on the FSS surface at the bottom centre of the corrugated strip, the tight coupling occurs and we show that the SPP modes are rejected near the resonance frequencies of ELC resonators. The steep roll-off at both sides of the stopband can be demonstrated by the ELC resonators, which can find potential applications in wideband antenna radome. In addition, the 3-D FSS shows relatively stable performance with different oblique incidence angles.

In this work, a broadband and broad-angle polarization-independent random coding metasurface structure is proposed for radar cross section (RCS) reduction. An efficient genetic algorithm is utilized to obtain the optimal layout of the unit cells of the metasurface to get a uniform backscattering under normal incidence. Excellent agreement between the simulation and experimental results show that the proposed metasurface structure can significantly reduce the radar cross section more than 10 dB from 17 GHz to 42 GHz when the angle of incident waves varies from 10° to 50°. The proposed coding metasurface provides an efficient scheme to reduce the scattering of the electromagnetic waves.

In this work, a wideband band-stop plasmonic filter based on localized spoof surface plasmons is reported, which consists of a coplanar waveguide (CPW) and an ultra-thin periodic corrugated metallic strip with defect units at the back of the substrate. Defect units are used to localize the transmission energy along the CPW. Each defect unit can introduce a narrow stop band, and a series of defect units is judiciously designed to form a broadband CPW band-stop filter. The center frequency and bandwidth of the filter can be tuned by the heights and numbers of the defect units. In addition, a T-shaped unit is designed to increase the equivalent height of the lateral branch so as to realize the miniaturization of the vertical geometric dimension. Theoretical analysis of the filter has been conducted, and a sample at microwave frequency has been fabricated and measured to validate our design. This simple band-stop plasmonic filter can find potential applications in plasmonic circuits and antennas at microwave and terahertz frequencies.

Large metallic losses and short propagation lengths associated with surface plasmons (SPs) have long been considered as the obstacles which severely limit the practical applications of surface plasmonic waveguides. In this paper, we introduce the concept of dielectric spoof SPs (SSPs) and show that subwavelength high-contrast gratings (HCGs) offer a route to effectively suppress the losses and hence dramatically increase the propagation length of surface electromagnetic waves. We experimentally realized a wideband ultra-low-loss high-confinement plasmonic waveguide constructed by a high refractive-index dielectric array with deep-subwavelength periodicity on a metal substrate. Simulation and measurement results on the near-field distributions and S-parameters at microwave frequencies provide explicit evidences of strong field localization and show excellent transmission efficiency of HCGs-based SSPs across a broad frequency band. More importantly, the propagation length of the HCGs-based SSPs is proved to be at least more than one order of magnitude larger than that of metallic gratings-based SSPs at the same or even higher level of field confinement. Thus, the SSPs as experimentally realized in this paper hold great promise for numerous practical applications in ultra-low-loss and long-range transmission SP devices and circuits and may open up new vistas in SP optics. MOE (Min. of Education, S’pore)

In this paper, a phase-gradient metasurface which consists of 7 arcuate cross-shaped metal-medium-metal units with different geometries is designed to realize anomalous reflection at 3GHz with 99% reflection efficiency of both x-polarized and y-polarized waves. The simulation results on near electric field distributions show excellent agreement of the anomalous reflection angle with theoretical analysis. This metasurface can be easily scaled to other frequency bands and find potential applications in optical communications.

In this work, we report the existence of spoof localized surface plasmons (spoof-LSPs) arising with closed high contrast gratings (HCGs) at deep subwavelength scales, another platform for field localization at microwave frequencies. The HCGs are in the form of a periodic array of radial dielectric blocks with high permittivity around a metal core supporting spoof-LSPs of transverse magnetic (TM) form. Simulation results validate the phenomenon and a metamaterial approach is also given to capture all the resonant features of this kind of spoof-LSPs. In addition, experimental verification of the existence of spoof-LSPs supported by a three dimensional (3D) HCGs resonance structure in the microwave regime is presented. This work expands the original spoof-LSPs theory and opens up a new avenue for obtaining resonance devices in the microwave frequencies.

This paper presents a generalized volume-surface integral equation (GVSIE) to solve electromagnetic (EM) scattering of high contrast inhomogeneous materials. Then the method of moments (MoM) is employed to solve the GVSIE. The GVSIE technique where the domain is represented by a corresponding uniform background medium coupled with a variation, together representing the overall inhomogeneity, is solve by the method of moments (MoM) using Schaubert-Wilton-Glisson (SWG) and Rao-Wilton-Glisson (RWG) basis functions. The adaptive cross approximation (ACA) algorithm combined with the equivalent dipole-moment (EDM) method are extended to reduce memory and CPU time. A highly efiective preconditioning strategy is presented to solve the system of equations without any increase in the computational complexity. Experiments on several problems representative of scattering simulations are given to illustrate the potential of the above proposed techniques for solving EM scattering involving high contrast applications.

In this work, a smooth bridge between a traditional microstrip line and a two parallel metallic strips drilled with symmetrical grooves is designed to achieve ultra-wideband low-pass filtering characteristics. Numerical simulations on the S-parameters demonstrate the good performance in the whole pass band. This kind of plasmonic filter poses potential applications in developing advanced plasmonic integrated circuits in the microwave and terahertz frequencies.

This Letter proposes a simple band-notched coplanar waveguide (BNCPW), which consists of a coplanar waveguide (CPW) and an ultra-thin periodic corrugated metallic strip that supports spoof surface plasmon polaritons (SSPPs) with defect units on the back of the substrate. By introducing a defect unit or multiple defect units into the strip, a narrow stopband or multiple narrow stopbands would be generated flexibly and conveniently. The band-notch function is based on the idea that a defect mode, which exists in the bandgap between the fundamental and the first higher mode of the SSPPs, can be introduced to form a stopband. Thus, the SSPPs field is localized around the defect units, which is another form of localized spoof surface plasmons (LSSPs). By properly tuning the dimensions of each defect unit, the absorption level and center frequency of the stopband could be adjusted independently. We offer theoretical analysis and experimental results to validate our idea and design. In this framework, a variety of band-notched devices and antennas in the microwave and terahertz (THz) frequencies can be easily designed without additional band-stop filters.

In this work, a band-pass plasmonic filter composed of a traditional microstrip line and a gradient metallic strip drilled with subwavelength holes is proposed. Numerical simulations on the S-parameters demonstrate the good performance in the pass band. This kind of plasmonic filter poses potential applications in developing advanced plasmonic integrated circuits in the microwave and terahertz frequencies.

A simple band-notched coplanar waveguide (BNCPW) is presented in this paper, which is designed based on the idea that a defect mode in the bandgap between the fundamental and higher modes of the spoof surface plasmon polaritons (SSPPs) can be introduced to form a stopband. The BNCPW, a quite simple structure, consists of a coplanar waveguide (CPW) and a periodic corrugated metallic strips on the back of the dielectric substrate. By properly tuning the geometrical parameters of the strips, we can introduce a very narrow stopband at will in the working band of the CPW. In this framework, a variety of band-notched devices and antenna can be easily designed without additional band-stop filters.

In this work, we explore the existence of multiband localized spoof plasmons (LSPs) in closed textured cavities with multiple groove depths. It is interesting to note that the spoof LSPs in each band resemble those generated by the textured 2D cavities of the same periodicity with the corresponding single groove depth, and the field distributions and confinement characteristics of the plasmon-like modes in such a corrugated cavity are different from the conventional cavity. Hence, these multiple resonance band structures can find potential applications in the microwave and terahertz frequencies.

An effective method for for controlling the absorption frequency of terahertz (THz) absorber based on graphene is presented in this paper. The absorber consists of graphene-dielectric stack with a resistive sheet on top layer and a perfect electric conductor placed at the bottom layer. A circuit model for graphene absorber was introduced to analyze the mechanism of the absorber. By changing the surface conductivity of graphene, fine tuning of the absorption resonances is achieved. The result of the proposed circuit model can be individually validated with the full-wave simulations, which are in a good agreement. In addition, the double-layer graphene-dielectric stack absorber exhibits stable resonances with respect to the incident plane wave at all oblique angles.

A rectangular waveguide (RW) to domino plas-monic waveguide (DPW) converter in X-band (8.2-12.4GHz), which is based on the high-efficiency conversion between guided waves and domino plasmon polaritons (DPPs), is proposed in this work. A matching transition composed by gradient domino arrays and flaring upper wall to match the wave number and impedance between the RW and DPW has been presented and designed. Simulated results on the S-parameters and near-field distributions show excellent transmission performance between the RW and DPW in the X-band. The proposed plasmonic metamaterial can find potential applications in advanced plasmonic integrated devices and circuits in the microwave and THz frequencies.

A kind of Chinese combined language model, that takes into account POS(part of speech) information in a trigram-based statistical language model, is presented in the paper. The theoretical analysis and experiments all show that the model not only is lower than trigram model in PP(perplexity), but also is superior to trigram model in dependence on testing text domain.

Graphene can be used as a platform for tunable absorbers for its tunability of conductivity. In this paper, we proposed an “uneven dielectric slab structure” for the terahertz (THz) tunable absorber based on graphene. The absorber consists of graphene-dielectric stacks and an electric conductor layer, which is easy to fabricate in the manufacturing technique. Fine tuning of the absorption resonances can be conveniently achieved by adjusting the bias voltage. Both narrowband and broadband tunable absorbers made of this structure are demonstrated without using a patterned graphene. In addition, this type of graphene-based absorber exhibits stable resonances with a wide range angles of obliquely incident electromagnetic waves.

The fast dipole method (FDM) is extended to analyze the scattering of dielectric and magnetic materials by solving the volume integral equation (VIE). The FDM is based on the equivalent dipole method (EDM) and can achieve the separation of the field dipole and source dipole, which reduces the complexity of interactions between two far groups (such as groupiand groupj) fromO(NiNj)toO(Ni+Nj), whereNiandNjare the numbers of dipoles in groupiand groupj, respectively. Targets including left-handed materials (LHMs), which are a kind of dielectric and magnetic materials, are calculated to demonstrate the merits of the FDM. Furthermore, in this study we find that the convergence may become much slower when the targets include LHMs compared with conventional electromagnetic materials. Numerical results about convergence characteristics are presented to show this property.

It has been demonstrated that textured closed surfaces are good platforms to support spoof localized surface plasmons with great field confinement and enhancement. Here, we propose a non-concentric textured closed structure to significantly increase the level of field confinement and enhancement. By properly texturing the closed surface with gradient-depth grooves, we show that the incoming electromagnetic waves can be highly confined and focused at the deepest groove on the closed surface. Moreover, we find that the field enhancement factor of this structure is quite sensitive to the polarization angle of the incident wave, which can find potential applications in polarization sensors and energy harvesting devices at microwave and terahertz frequencies.

In this work, a bandwidth tunable microstrip band-stop filter is theoretically investigated and experimentally verified based on the concept of localized spoof surface plasmons. By placing a conventional microstrip at the bottom center of a symmetrically periodically corrugated metallic strip, which supports spoof surface plasmons with a single defect or a series of defects of continuously variable dimensions, localization of the quasi-static field propagating along the microstrip can be realized, thus facilitating control of the central frequency, bandwidth, and absorption level of the microstrip band-stop filter. A band-notched microstrip and a band-stop one are cautiously designed and verified through simulations and experiments, which can find potential applications in microwave band-stop circuits.

In this letter, dual-band trapping of spoof surface plasmon polaritons (SSPPs) is realized by a simple surface plasmon waveguide (SPW), which takes the form of a microstrip line with periodic holes. A tapered microstrip line with periodic gradient holes is built for efficient mode conversion between the quasi-transverse electromagnetic waves in the common microstrip line and the SSPPs on the SPW. It is interesting to note that negative group velocity can be clearly observed on the first high-order mode of such SPW due to the strong coupling between the corrugated microstrip line and ground. A curved SPW of the same form is also investigated for testing its field confinement and circuitry function. Measurement results agree quite well with the simulation ones, which indicate this SPW can find potential applications in plasmonic integrated circuits at microwave and terahertz frequencies.

In this work, we build a smooth bridge between a coaxial waveguide and a plasmonic waveguide with subwavelength periodically cylindrical radial grooves, to realize high-efficiency mode conversion between conventional guided waves and spoof surface plasmon polaritons in broadband. This bridge consists of a flaring coaxial waveguide connected with a metal cylindrical wire corrugated with subwavelength gradient radial grooves. Experimental results of the transmission and reflection coefficients show excellent agreement with the numerical simulations. The proposed scheme can be extended readily to other bands and the bridge structure can find potential applications in the integration of conventional microwave or terahertz devices with plasmonic circuits.

We proposed a neural network that can interpret multimeaning Chinese words correctly by using context information. The network is generated automatically basing on a Chinese-English dictionary and a knowledge-base of weights and self-organizingly builds a context according to key words of the processed text. Simulation experiment result proved that the network worked as expected.

In this work, we demonstrate that composite spoof surface plasmon polaritons can be excited by coplanar waveguide, which are composed of two different spoof surface plasmon polaritons (SSPPs) modes propagating along a periodically corrugated metallic thin film simultaneously. These two SSPPs correspond to the dominant modes of one-dimensional (1D) periodical hole and groove arrays separately. We have designed and simulated a planar composite plasmonic waveguide in the microwave frequencies, and the simulation results show that the composite plasmonic waveguide can achieve multi-channel signal transmission with good propagation performance. The proposed planar composite plasmonic metamaterial can find potential applications in developing surface wave devices in integrated plasmonic circuits and multi-channel signal transmission systems in the microwave and terahertz frequencies.

Localized spoof plasmons arising with textured closed surfaces have been theoretically studied and experimentally verified, which resemble the localized surface plasmons (LSPs) in the optical regime. In this work, we go one step further and demonstrate that part of the resonance modes in closed textured cavities pertain to spoof localized surface plasmons (spoof-LSPs) modes. We show the existence of spoof LSPs in periodically textured perfect electric conductor circular cavities and make an analogy between these spoof LSPs and the real LSPs in closed metallic cavities with the Drude model in the optical regime. Also, a metamaterial approach is presented to capture the resonant features of these modes.

A general circuit model is presented to study the absorption of electromagnetic waves by a graphene-based structure at low-terahertz frequencies. The absorber consists of a monolayer graphene which is printed on the uneven dielectric slabs, with a metallic ground plane placed at the bottom interface. The approach is based on the simple and accurate analytical models for metal strips or patches. Compared with the full-wave electromagnetic simulator software, the proposed method shows high efficiency and the results obtained from the suggested method agree well with those from the full-wave simulations for a normal and oblique incidence. It is very helpful to design novel graphene plasmonic devices in the future.

In this paper, we demonstrate that spoof surface magnon polaritons (SSMPs) can propagate along a corrugated perfect magnetic conductor (PMC) surface. From duality theorem, the existence of surface electromagnetic modes on corrugated PMC surfaces are manifest to be transverse electric (TE) mode compared with the transverse magnetic (TM) mode of spoof surface plasmon plaritons (SSPPs) excited on corrugated perfect electric conductor surfaces. Theoretical deduction through modal expansion method and simulation results clearly verify that SSMPs share the same dispersion relationship with the SSPPs. It is worth noting that this metamaterial will have more similar properties and potential applications as the SSPPs in large number of areas.

We proposed a neural network that can interpret multi-meaning Chinese words correctly by using context information. The self-organized network, designed for translating Chinese to English, builds a context according to key words of the processed text and utilizes it to interpret multi-meaning words correctly. The network is generated automatically basing on a Chinese-English dictionary and a knowledge-base of weights, and can adapt to the change of contexts. Simulation experiments have proved that the network worked as expected.