Broadband multi-channel quantum noise suppression and phase-sensitive modulation based on entangled beam

We present a theoretical scheme for broadband multi-channel quantum noise suppression and phase-sensitive modulation of continuous variables in a coupled resonant system with quantum entanglement properties.The effects of different coupling strengths,pumping power in suppressing quantum noise and controlling the width of quantum interference channels are analyzed carefully.Furthermore,quantum noise suppression at quadrature amplitude is obtained with phase-sensitive modulation.It shows that the entanglement strength of the output field and the quantum noise suppression effect can be enhanced significantly by a strong pumping filed due to interaction of pumping light with the nonlinear crystal.The full width at half maxima(FWHM)of the noise curve at the resonant peak(△=0 MHz)is broadened up to 2.17 times compared to the single cavity.In the strong coupling resonant system,the FWHM at △=0 MHz(△=±3.1 MHz)is also broadened up to 1.27(3.53)times compared to the weak coupling resonant system case.The multi-channel quantum interference creates an electromagnetically induced transparent-like line shape,which can be used to improve the transmission efficiency and stability of wave packets in quantum information processing and quantum memory.

Broadband Dual-Input Doherty Power Amplifier Design Based on a Simple Adaptive Power Dividing Ratio Function

In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.

A novel multi-channel porous structure facilitating mass transport towards highly efficient alkaline water electrolysis

An advantageous porous architecture of electrodes is pivotal in significantly enhancing alkaline water electrolysis(AWE)efficiency by optimizing the mass transport mechanisms.This effect becomes even more pronounced when aiming to achieve elevated current densities.Herein,we employed a rapid and scalable laser texturing process to craft novel multi-channel porous electrodes.Particularly,the obtained electrodes exhibit the lowest Tafel slope of 79 mV dec^(-1)(HER)and 49 mV dec^(-1)(OER).As anticipated,the alkaline electrolyzer(AEL)cell incorporating multi-channel porous electrodes(NP-LT30)exhibited a remarkable improvement in cell efficiency,with voltage drops(from 2.28 to 1.97 V)exceeding 300 mV under 1 A cm^(-1),compared to conventional perforated Ni plate electrodes.This enhancement mainly stemmed from the employed multi-channel porous structure,facilitating mass transport and bubble dynamics through an innovative convection mode,surpassing the traditional convection mode.Furthermore,the NP-LT30-based AEL cell demonstrated exceptional durability for 300 h under 1.0 A cm^(-2).This study underscores the capability of the novel multi-channel porous electrodes to expedite mass transport in practical AWE applications.

A flexible ultra-broadband multi-layered absorber working at 2 GHz-40 GHz printed by resistive ink

A flexible extra broadband metamaterial absorber(MMA)stacked with five layers working at 2 GHz–40 GHz is investigated.Each layer is composed of polyvinyl chloride(PVC),polyimide(PI),and a frequency selective surface(FSS),which is printed on PI using conductive ink.To investigate this absorber,both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided.Various crucial electromagnetic properties,such as absorption,effective impedance,complex permittivity and permeability,electric current distribution and magnetic field distribution at resonant peak points,are studied in detail.Analysis shows that the working frequency of this absorber covers entire S,C,X,Ku,K and Ka bands with a minimum thickness of 0.098λ_(max)(λ_(max) is the maximum wavelength in the absorption band),and the fractional bandwidth(FBW)reaches 181.1%.Moreover,the reflection coefficient is less than-10 dB at 1.998 GHz–40.056 GHz at normal incidence,and the absorptivity of the plane wave is greater than 80%when the incident angle is smaller than 50°.Furthermore,the proposed absorber is experimentally validated,and the experimental results show good agreement with the simulation results,which demonstrates the potential applicability of this absorber at 2 GHz–40 GHz.

Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials

In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.

Design of Cold-Junction Compensation and Disconnection Detection Circuits of Various Thermocouples and Implementation of Multi-Channel Interfaces Using Them-A Secondary Publication

Cold-junction compensation(CJC)and disconnection detection circuit design of various thermocouples(TC)and multi-channel TC interface circuits were designed.The CJC and disconnection detection circuit consists of a CJC semiconductor device,an instrumentation amplifier(IA),two resistors,and a diode for disconnection detection.Based on the basic circuit,a multi-channel interface circuit was also implemented.The CJC was implemented using compensation semiconductor and IA,and disconnection detection was detected by using two resistors and a diode so that IA input voltage became-0.42 V.As a result of the experiment using R-type TC,the error of the designed circuit was reduced from 0.14 mV to 3μV after CJC in the temperature range of 0°C to 1400°C.In addition,it was confirmed that the output voltage of IA was saturated from 88 mV to-14.2 V when TC was disconnected from normal.The output voltage of the designed circuit was 0 V to 10 V in the temperature range of 0°C to 1400°C.The results of the 4-channel interface experiment using R-type TC were almost identical to the CJC and disconnection detection results for each channel.The implemented multi-channel interface has a feature that can be applied equally to E,J,K,T,R,and S-type TCs by changing the terminals of CJC semiconductor devices and adjusting the IA gain.

Gradient carbonyl-iron/carbon-fiber reinforced composite metamaterial for ultra-broadband electromagnetic wave absorption by multi-scale integrated design

The demand of high-end electromagnetic wave absorbing materials puts forward higher requirements on comprehensive performances of small thickness,lightweight,broadband,and strong absorption.Herein,a novel multi-layer stepped metamaterial absorber with gradient electromagnetic properties is proposed.The complex permittivity and permeability of each layer are tailored via the proportion of carbonyliron and carbon-fiber dispersing into the epoxy resin.The proposed metamaterial is further optimized via adjusting the electromagnetic parameters and geometric sizes of each layer.Comparing with the four-layer composite with gradient electromagnetic properties which could only realize reflection loss(RL)of less than−6 dB in 2.0-40 GHz,the optimized stepped metamaterial with the same thickness and electromagnetic properties realizes less than−10 dB in the relevant frequency range.Additionally,the RL of less than−15 dB is achieved in the frequency range of 11.2-21.4 GHz and 28.5-40 GHz.The multiple electromagnetic wave absorption mechanism is discussed based on the experimental and simulation results,which is believed to be attributed to the synergy effect induced by multi-scale structures of the metamaterial.Therefore,combining multi-layer structures and periodic stepped structures into a novel gradient absorbing metamaterial would give new insights into designing microwave absorption devices for broadband electromagnetic protections.

Self-Supporting Nanoporous Copper Film with High Porosity and Broadband Light Absorption for Efficient Solar Steam Generation

Solar steam generation(SSG)is a potential technology for freshwater production,which is expected to address the global water shortage problem.Some noble metals with good photothermal conversion performance have received wide concerns in SSG,while high cost limits their practical applications for water purification.Herein,a self-supporting nanoporous copper(NP-Cu)film was fabricated by one-step dealloying of a specially designed Al_(98)Cu_(2)precursor with a dilute solid solution structure.In-situ and ex-situ characterizations were performed to reveal the phase and microstructure evolutions during dealloying.The NP-Cu film shows a unique three-dimensional bicontinuous ligament-channel structure with high porosity(94.8%),multi scale-channels and nanoscale ligaments(24.2±4.4nm),leading to its strong broadband absorption over the 200–2500 nm wavelength More importantly,the NP-Cu film exhibits excellent SSG performance with high evaporation rate,superior efficiency and good stability.The strong desalination ability of NP-Cu also manifests its potential applications in seawater desalination.The related mechanism has been rationalized based upon the nanoporous network,localized surface plasmon resonance effect and hydrophilicity.

Dielectric loss enhancement induced by the microstructure of CoFe_(2)O_(4) foam to realize broadband electromagnetic wave absorption

CoFe_(2)O_(4)has been widely used for electromagnetic wave absorption owing to its high Snoek limit,high anisotropy,and suitable saturation magnetization;however,its inherent shortcomings,including low dielectric loss,high density,and magnetic agglomeration,limit its application as an ideal absorbent.This study investigated a microstructure regulation strategy to mitigate the inherent disadvantages of pristine CoFe_(2)O_(4)synthesized via a sol–gel auto-combustion method.A series of CoFe_(2)O_(4)foams(S0.5,S1.0,and S1.5,corresponding to foams with citric acid(CA)-to-Fe(NO_(3))_(3)·9H_(2)O molar ratios of 0.5,1.0,and 1.5,respectively)with two-dimensional(2D)curved surfaces were obtained through the adjustment of CA-to-Fe^(3+)ratio,and the electromagnetic parameters were adjusted through morphology regulation.Owing to the appropriate impedance matching and conductance loss provided by moderate complex permittivity,the effective absorption bandwidth(EAB)of S0.5 was as high as 7.3 GHz,exceeding those of most CoFe_(2)O_(4)-based absorbents.Moreover,the EAB of S1.5 reached 5.0 GHz(8.9–13.9 GHz),covering most of the X band,owing to the intense polarization provided by lattice defects and the heterogeneous interface.The three-dimensional(3D)foam structure circumvented the high density and magnetic agglomeration issues of CoFe_(2)O_(4)nanoparticles,and the good conductivity of 2D curved surfaces could effectively elevate the complex permittivity to ameliorate the dielectric loss of pure CoFe_(2)O_(4).This study provides a novel idea for the theoretical design and practical production of lightweight and broadband pure ferrites.

Multi-channel terahertz focused beam generator based on shared-aperture metasurface

Most of existing metasurfaces usually have limited channel behavior,which seriouslyhinders their development and application.In this paper,we propose a multi-channel terahertz focused beam generator based on shared-aperture metasurface,and the generator consists of a top square metal strip,a middle layer of silica and a metal bottom plate.By changing the position and size of the shared-aperture array,the designed metasurface can generate any number of multi-channel focusing beams at different predicted positions.In addition,the energy intensity of focusing beams can be controlled.The full-wave simulation results show that the metasurface achieves four-channel vortex focused beam generation with different topological charges,and five-,six-,eight-channel focused beam generation with different energy intensities at a frequency of 1 THz,which are in good agreement with the theoretically calculated predictions.This work can provide a new idea for designing the terahertz multichannel devices.

Fast pre-stack multi-channel inversion constrained by seismic reflection features

Classical multi-channel technology can significantly reduce the pre-stack seismic inversion uncertainty, especially for complex geology such as high dipping structures. However, due to the consideration of complex structure or reflection features, the existing multi-channel inversion methods have to adopt the highly time-consuming strategy of arranging seismic data trace-by-trace, limiting its wide application in pre-stack inversion. A fast pre-stack multi-channel inversion constrained by seismic reflection features has been proposed to address this issue. The key to our method is to re-characterize the reflection features to directly constrain the pre-stack inversion through a Hadamard product operator without rearranging the seismic data. The seismic reflection features can reflect the distribution of the stratum reflection interface, and we obtained them from the post-stack profile by searching the shortest local Euclidean distance between adjacent seismic traces. Instead of directly constructing a large-size reflection features constraint operator advocated by the conventional methods, through decomposing the reflection features along the vertical and horizontal direction at a particular sampling point, we have constructed a computationally well-behaved constraint operator represented by the vertical and horizontal partial derivatives. Based on the Alternating Direction Method of Multipliers (ADMM) optimization, we have derived a fast algorithm for solving the objective function, including Hadamard product operators. Compared with the conventional reflection features constrained inversion, the proposed method is more efficient and accurate, proved on the Overthrust model and a field data set.

Ultralight pyrolytic carbon foam reinforced with amorphous carbon nanotubes for broadband electromagnetic absorption

For electromagnetic wave-absorbing materials,maximizing absorption at a specific frequency has been constantly achieved,but enhancing the absorption properties in the entire band remains a challenge.In this work,a 3D porous pyrolytic carbon(PyC)foam matrix was synthesized by a template method.Amorphous carbon nanotubes(CNTs)were then in-situ grown on the matrix surface to obtain ultralight CNTs/Py C foam.These in-situ grown amorphous CNTs were distributed uniformly and controlled by the catalytic growth time and can enhance the interface polarization and conduction loss of composites.When the electromagnetic wave enters the internal holes,the electromagnetic energy can be completely attenuated under the combined action of polarization,conductivity loss,and multiple reflections.The ultralight CNTs/Py C foam had a density of 22.0 mg·cm^(-3)and a reflection coefficient lower than-13.3 d B in the whole X-band(8.2-12.4 GHz),which is better than the conventional standard of effective absorption bandwidth(≤-10 dB).The results provide ideas for researching ultralight and strong electromagnetic wave absorbing materials in the X-band.

Lightweight broadband microwave absorbing metamaterial with CB-ABS composites fabricated by 3D printing

The self-similarity,high geometric symmetry and spatial utilization properties of fractal structures provide new methods for the development of absorbing metamaterials.In this paper,the microwave absorption properties of the gradient dendritic fractal metamaterial structure(GDFMs)based on carbon black and acrylonitrile-butadiene-styrene composites were investigated.The optimal metamaterial structure has an effective absorption in the frequency range of 4.5-40 GHz.The rotational-symmetry GDFMs leads to the polarization independence,and the GDFMs exhibits a wide-angle absorption performance for both TE and TM waves.It is expected that the proposed GDFMs has good application prospects in electromagnetic wave absorption.

A fast-response self-powered UV–Vis–NIR broadband photodetector based on a AgIn_(5)Se_(8)/t-Se heterojunction

A type Ⅱ p–n heterojunction could improve the photodetection performance of a photodetector due to the excellent ability of carrier separation. N-type AgIn_(5)Se_(8)(AIS) exhibits a large optical absorption coefficient, high optical conductivity and a suitable bandgap, and shows potential application in broadband photodetection. Even though our previous study on AgIn_(5)Se_(8)/FePSe_(3)obtained a good response speed, it still gave low responsivity due to the poor quality of the p-type FePSe_(3)thin film. Se, with a direct bandgap(around 1.7 eV), p-type conductivity, high electron mobility and high carrier density,is likely to form a low-dimensional structure, which leads to an increase in the effective contact area of the heterojunction and further improves the photodetector performance. In this work, continuous and dense t-Se thin film was prepared by electrochemical deposition. The self-powered AgIn5Se8/t-Se heterojunction photodetector exhibited a broadband detection range from 365 nm to 1200 nm. The responsivity and detectivity of the heterojunction photodetector were 32 μA/W and 1.8×109Jones, respectively, which are around 9 and 4 times higher than those of the AgIn_(5)Se_(8)/FePSe_(3)heterojunction photodetector. The main reason for this is the good quality of the t-Se thin film and the formation of the low-dimensional t-Se nanoribbons, which optimized the transport pathway of carriers. The results indicate that the AgIn_(5)Se_(8)/t-Se heterojunction is an excellent candidate for broadband and self-powered photoelectronic devices.

Broadband ground motion simulation using a hybrid approach of the May 21, 2021 M7.4 earthquake in Maduo, Qinghai, China

In this study,the broadband ground motions of the 2021 M7.4 Maduo earthquake were simulated to overcome the scarcity of ground motion recordings and the low resolution of macroseismic intensity map in sparsely populated high-altitude regions.The simulation was conducted with a hybrid methodology,combining a stochastic high-frequency simulation with a low-frequency ground motion simulation,from the regional 1-D velocity structure model and the Wang WM et al.(2022)source rupture model,respectively.We found that the three-component waveforms simulated for specific stations matched the waveforms recorded at those stations,in terms of amplitude,duration,and frequency content.The validation results demonstrate the ability of the hybrid simulation method to reproduce the main characteristics of the observed ground motions for the 2021 Maduo earthquake over a broad frequency range.Our simulations suggest that the official map of macroseismic intensity tends to overestimate shaking by one intensity unit.Comparisons of simulations with empirical ground motion models indicate generally good consistency between the simulated and empirically predicted intensity measures.The high-frequency components of ground motions were found to be more prominent,while the low-frequency components were not,which is unexpected for large earthquakes.Our simulations provide valuable insight into the effects of source complexity on the level and variability of the resulting ground motions.The acceleration and velocity time histories and corresponding response spectra were provided for selected representative sites where no records were available.The simulated results have important implications for evaluating the performance of engineering structures in the epicentral regions of this earthquake and for estimating seismic hazards in the Tibetan regions where no strong ground motion records are available for large earthquakes.

Opportunistic Routing with Multi-Channel Cooperative Neighbour Discovery

Due to the scattered nature of the network,data transmission in a dis-tributed Mobile Ad-hoc Network(MANET)consumes more energy resources(ER)than in a centralized network,resulting in a shorter network lifespan(NL).As a result,we build an Enhanced Opportunistic Routing(EORP)protocol architecture in order to address the issues raised before.This proposed routing protocol goal is to manage the routing cost by employing power,load,and delay to manage the routing energy consumption based on theflooding of control pack-ets from the target node.According to the goal of the proposed protocol techni-que,it is possible to manage the routing cost by applying power,load,and delay.The proposed technique also manage the routing energy consumption based on theflooding of control packets from the destination node in order to reduce the routing cost.Control packet exchange between the target and all the nodes,on the other hand,is capable of having an influence on the overall efficiency of the system.The EORP protocol and the Multi-channel Cooperative Neighbour Discovery(MCCND)protocol have been designed to detect the cooperative adja-cent nodes for each node in the routing route as part of the routing path discovery process,which occurs during control packet transmission.While control packet transmission is taking place during the routing path discovery process,the EORP protocol and the Multi-channel Cooperative Neighbour Discovery(MCCND)protocol have been designed to detect the cooperative adjacent nodes for each node in the routing.Also included is a simulation of these protocols in order to evaluate their performance across a wide range of packet speeds using Constant Bit Rate(CBR).When the packet rate of the CBR is 20 packets per second,the results reveal that the EORP-MCCND is 0.6 s quicker than the state-of-the-art protocols,according to thefindings.Assuming that the CBR packet rate is 20 packets per second,the EORP-MCCND achieves 0.6 s of End 2 End Delay,0.05 s of Routing Overhead Delay,120 s of Network Lifetime,and 20 J of Energy Consumption efficiency,which is much better than that of the state-of-the-art protocols.

Effects of time-delayed vibration absorber on bandwidth of beam for low broadband vibration suppression

The effects of time-delayed vibration absorber(TDVA) on the dynamic characteristics of a flexible beam are investigated. First, the vibration suppression effect of a single TDVA on a continuous beam is studied. The first optimization criterion is given,and the results show that the introduction of time-delayed feedback control(TDFC) is beneficial to improving the vibration suppression at the anti-resonance band. When a single TDVA is used, the anti-resonance is located at a specific frequency by the optimum design of TDFC parameters. Then, in order to obtain low-frequency and broad bands for vibration suppression, multiple TDVAs are uniformly distributed on a continuous beam,and the relationship between the dynamic responses and the TDFC parameters is investigated. The obtained relationship shows that the TDVA has a significant regulatory effect on the vibration behavior of the continuous beam. The effects of the number of TDVAs and the nonlinearity on the bandgap variation are discussed. As the multiple TDVAs are applied, according to the different requirements on the location and bandwidth of the effective vibration suppression band, the optimization criteria for the TDFC parameters are given, which provides guidance for the applications of TDVAs in practical projects such as bridge and aerospace.

A Miniaturized Broadband Wilkinson Power Divider Using Micro-Strip Branch Lines

A miniaturized broadband Wilkinson power divider is proposed. Micro-strip branch lines are introduced to replace multiple resistors used in multi-stage Wilkinson power dividers to increase the bandwidth of single-stage Wilkinson power dividers. To demonstrate its performance, an improved single-stage Wilkinson power divider with four micro-strip branch lines was designed. Simulated results show that the insert loss is better than 3.2 dB, the input return loss, output return loss, and isolation are better than 15 dB respectively, across a 76% bandwidth from 18 to 40 GHz. .

数字经济与城市旅游绩效研究--基于城市面板数据的实证分析

旅游产业高质量发展对推进中国式现代化具有重要作用。本文利用中国城市面板数据,实证分析数字经济对城市旅游绩效的影响。研究发现:数字经济发展可以显著提高城市旅游绩效,具体表现为数字经济发展水平越高,则该城市的人均旅游总收入和人均旅游接待总人次越多,该结论在运用工具变量和选用“宽带中国”试点作为准自然实验缓解潜在的内生性问题后仍然稳健。异质性检验显示:在金融发展较落后地区和市场化进程较缓慢地区,数字经济对城市旅游绩效的促进作用更加显著。据此,本文提出充分利用数字经济赋能旅游经济、政府主导制定差异化产业政策、加强数字与旅游政策协同的政策建议。

基于InSe/MoTe_(2)异质结构的超灵敏宽光谱光电探测器

基于光栅效应的二维材料垂直结构可实现高灵敏度和宽光谱光探测器。本文报告了一种基于硒化铟(InSe)/二碲化钼(MoTe_(2))垂直异质结构的高灵敏度光电探测器,该探测器在365~965 nm波长范围内具有出色的宽光谱探测能力。顶层的InSe用作调节沟道电流的光栅层,MoTe_(2)则用作传输层。通过结合两种材料的优势,该光电探测器的响应时间为21.6 ms,比探测率在365 nm光照下可以达到1.05×10^(13)Jones,在965 nm光照下也可达到109 Jones数量级。外量子效率可达1.03×10^(5)%,显示出强大的光电转换能力。