Mixed Coupling Research Articles

Compact Low-Loss Half-Mode Substrate Integrated Waveguide Filter With Controllable Transmission Zeros

Two novel planar filters with controllable mixed electromagnetic couplings are developed in this brief for C band operation. They are implemented with the half mode substrate integrated waveguide (HMSIW) technology. Owing to the half mode SIW cavity, both of the filters exhibit a compact size. The size of filter I is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.53\,\,{\boldsymbol{\lambda }}_{\mathbf {0}} \times 0.30 {\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> , while the size of filter II is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.47\,\,{\boldsymbol{\lambda }}_{\mathbf {0}} \times 0.28 {\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> . ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\boldsymbol{\lambda }}_{\mathbf {0}}$ </tex-math></inline-formula> represents the wavelength in the free space at the center frequency). A wide passband response with a quasi-elliptic characteristic and good out-of-band rejection is realized due to the transmission zeros (TZs) introduced by the etched slot structures on the top metal layer. By modifying the dimensions of the structure, the strength of the electric and magnetic coupling can be independently controlled, and consequently the position of TZs is controllable to achieve desired stopband response with high selectivity. As a validation of the concept, one prototype is fabricated and tested. Excellent agreement is observed between the simulated and measured results.

Analysis of material susceptibility in silicon on insulator waveguides with combined simulation of four-wave mixing and linear mode coupling

We derive propagation equations modeling third-order susceptibility-induced nonlinear interaction and linear mode coupling in waveguides. We model material susceptibility with Raman and electronic response which include approximations suited for optical communications. We validate our model by comparing numerical integration of the propagation equations to continuous wave measurements of a silicon on insulator waveguide.

Experimental and Numerical Study on Mixed Lubrication Performance of Journal Bearing Considering Misalignment and Thermal Effect

The shaft misalignment under mixed lubrication is an important factor affecting the running performance of the bearing, which can occur under heavy load and unsatisfactory assembly. This paper presents a misaligned journal mixed lubrication model coupling for the asperity contact effect, elastic deformation, viscosity–temperature, and viscosity–pressure effect. The finite difference method was employed to calculate the model, and an experimental apparatus designed in this paper was used to test the friction and temperature characteristics of the specimens. The results show that the pressure field, film thickness, and elastic deformation of the bearing conformed to asymmetric distribution along the axial direction under misalignment conditions and there was a notable end side effect. In addition, the frictional force and side leakage flow were evidently enhanced with the increase in the inclination angle in a certain range. The experimental results showed that there was a visible wear phenomenon on the end sides of the bush and shaft. The research results are beneficial for understanding the mixed lubrication mechanism of misaligned journal bearing.

A High Out-of-Band Suppressed Compact Wideband Filtering Dipole Antenna With a Dual-Mode Compressed Parasitic Folded Dipole

This article presents a design of a high out-of-band suppressed compact wideband filtering dipole antenna with a dual-mode compressed parasitic folded dipole. The proposed antenna consists of a half-wavelength dipole and a compressed parasitic folded dipole. The half-wavelength mode and the one and a half-wavelength mode of the parasitic folded dipole are excited simultaneously. A capacitive load is utilized to tune the resonance of the half-wavelength mode of the parasitic folded dipole to make it come close to the resonant frequency of the one and a half-wavelength mode. Then, the parasitic element and the driven dipole couple with each other to achieve a wide bandwidth. Moreover, mixed coupling is observed between the driven dipole and the parasitic folded dipole, which results in the radiation nulls at the lower and the upper band, respectively. The antenna is fabricated and measured. The measurements reveal that a wide bandwidth of 37.9% is attained with an omnidirectional radiation pattern. Three radiation nulls can be observed at 580, 990, and 1545 MHz. The level of the out-of-band suppression achieves 15.1 dB. Only two resonators are utilized in this design, which makes the proposed antenna simple and compact.

A novel self‐packaged DBBPF with multiple TZs for 5G sub‐6 GHz applications

AbstractIn this article, we proposed a self‐packaged dual‐band bandpass filter (DBBPF) with high isolation and low insertion loss (IL) for 5G sub‐6 GHz applications. To get high stopband suppression, multiple and controllable transmission zeros (TZs) are introduced. A pair of quarter‐wavelength stepped‐impedance resonators (QSIRs) and half‐wavelength hairpin resonators (HWHR) are introduced to form a cross‐coupled five‐star topology to generate two passbands and multiple TZs analyzed by mixed electromagnetic couplings. A pair of U‐shape resonators are designed on G6 to fully excite the resonators and introduce source/load TZs at the same time. The generation of TZs by separate electric and magnetic coupling paths (SEMCP) is discussed. The DBBPF achieves a low IL of 0.85/1.13 dB with fractional bandwidths (FBW) of 11.0%/6.9% at center frequencies of 3.45 and 4.9 GHz for 5G sub‐6 GHz applications, respectively. The total size is only 0.32 λg × 0.45 λg.

Dual-Band Filtering Switches Using Multimode Dielectric Resonators With Hybrid Boundaries

Miniaturized dual-band filtering switches are proposed in this article using multimode dielectric resonators (DRs). The planar printed circuit boards (PCBs) are utilized not only to construct the hybrid electromagnetic boundary for quad-mode DR, but also to offer the switchable multimode feeding structures with the p-i-n diodes. When the diodes are reversely biased, all the four modes are excited simultaneously by the mixed electric and magnetic couplings and controlled flexibly to construct the dual-band response. In this manner, extra losses from diodes are avoided, and low-loss transmission is realized. When the diodes are forward biased, all the four modes are shut off at the same time. Owing to the used mixed electric and magnetic couplings, the isolation is enhanced further by the cancellation of the electric and magnetic couplings between the feeding line and the resonant modes. For demonstration, both dual-mode and quad-mode filtering switches with dual-band operations are fabricated and tested. With only one quad-mode DR, high performance, including low-loss dual-band transmission and high-level isolation, is observed in the measurement, making the proposed switches promising in high-standard multiband time division duplex (TDD) systems.

Multi-objective capacity programming and operation optimization of an integrated energy system considering hydrogen energy storage for collective energy communities

A novel grid-linked integrated energy system design combined with hydrogen energy storage for collective energy communities has been proposed and analyzed, which is driven by natural gas and solar energy to achieve coordinated supply of cooling, heating and power. The models of energy devices were established in detail, and a multi-variable multi-objective mixed integer nonlinear programming coupling maximum rectangle method and particle swarm optimization was adopted. The optimal configuration and indicators were obtained based on the comprehensive assessment of energy, economics, environment and grid dependence. A hybrid operation strategy following objective function has been developed to improve the overall performance. A real case in Xi’an of Northwest China was chosen to study according to the simulated load demand, three operation strategies were compared, hourly energy management was assessed, and four electrical energy storage schemes were contrasted. Finally, the scheme that uses surplus electricity to electrolyze water for producing hydrogen to supply consumers under hybrid operation strategy is the optimum selection and the annual hydrogen supply is as high as 81,673 kg. Besides, the effects of main device efficiencies, natural gas price and electricity price on system performance were discussed. The results indicated that the power generation efficiency of gas turbine and market factors have the most conspicuous impact on the proposed system. This work may provide theoretical guidance for relevant research and application.

Intrinsic low-dimensional manifold (ILDM)-based concept for the coupling of turbulent mixing with manifold-based simplified chemistry for the turbulent flame simulation

Manifold based simplified chemistry is an efficient reduction technique for the chemical kinetics, which aims to reduce the computational effort in numerical simulations. While the concept of reduced chemistry has been used for decades and various models have been developed up to now, their coupling with turbulent physical processes (e.g., mixing processes) has not been investigated extensively. This is attributed to the fact that the turbulent physical processes act as perturbation to the chemistry which pulls the thermo-kinetic states away from the manifold, and these states must relax back onto the manifold again. The present work gives insight into the coupling of reduced kinetic and the turbulent mixing processes. Accordingly, a strategy based on the Intrinsic Low-Dimensional Manifold concept is proposed. This coupling strategy is validated through the well-known Sandia Flame series. It is shown that the numerical results agree very well with those using detailed chemistry (no coupling model required) and experimental measurement. The suggested coupling strategy can be used for any manifold based simplified chemistry.

Delayed distributed impulsive synchronization of coupled neural networks with mixed couplings

In this paper, synchronization problem of coupled neural networks (CNNs) with both the distributed delay coupling (DDC) and the nonlinear coupling is studied. Firstly, a novel array of delayed inequalities with mixed delays is introduced. Specifically, mixed delays involve the distributed delay and discrete impulsive delays. Stemmed from such newly proposed inequalities, some sufficient conditions ensuring the exponential synchronization of CNNs are obtained by utilizing technique of linear matrix inequalities (LMIs) and Kronecker product. Furthermore, the delay-dependent distributed impulsive controller is devised, where discrete delays can be nonidentical at different impulsive instants. In addition, we pay special attention on synchronization issue of large-scale CNNs and derive some low-dimensional sufficient conditions by employing the technique of the matrix decomposition. Finally, two illustrative numerical examples are provided to demonstrate the effectiveness of theoretical results.

Ground states of nonlinear Schrödinger systems with mixed couplings: the critical case

In this paper, we consider the following k-coupled nonlinear Schrödinger systems in the critical case: Here, is a smooth bounded domain, and for every , where is the first eigenvalue of with the Dirichlet boundary condition. Note that the nonlinearity and the coupling terms are both critical in dimension 4 (i.e. when ). We call the couplings are attractive if , while repulsive stands for . Under the assumption that all the couplings are purely attractive and large enough, we first show that this critical system has a fully nontrivial ground state solution, that is, a solution has all components nontrivial, under conditions providing additional , while ground state solution may be semitrivial ( has null components) without the above additional conditions. When the systems admit mixed couplings, i.e. there exist and such that and , we establish the existence of least energy positive solutions. The purpose of this paper is to solve some remaining open questions on Tavares and You (Calc. Var. Partial Differential Equations 59:26, 2020).

The Balance between the Legal Norms of Treaties and National Legislation of Israel in the field of the Right to Marriage and Family. Regulation of the Divorce Procedure for Mixed (Interfaith) Couples

The paper considers one of the most specific systems of law that includes modern democratic norms of law and conservative, religious traditions. This system of law is the national family law of the State of Israel. The centuries-old religious norms of law in the field of marriage and family relations remained archaic until the declaration of Israel’s independence. This resulted in the creation of a new national system of legislation that met international standards. However, due to the importance of preserving traditions, as well as the zealous attitude to their observance on the part of religious groups living in Israel, the norms of religious law in the field of marriage and family relations have become an obligatory part of the legislation in this area of law. At the same time, being a progressive state to the extent possible, Israel is constantly developing the legal framework in the field of human rights, especially the right to marriage and family, in accordance with all the norms of treaties to which it is a signatory. The norms of Jewish law, Muslim law are an obligatory part of the laws of the State of Israel, in particular in regulating the divorce procedure. The divorce among Jewish couples, as well as Muslim couples, is carried out in accordance with the norms of the religious law of each denomination, which are enshrined in the regulatory legal acts of the State of Israel. However, cases of termination of marital relations of mixed (interfaith) couples are not an exception. In connection with the complication of relations at the present stage, it is necessary to constantly develop legislation in the field of divorce procedure, especially in cases of termination of marital relations of mixed (interfaith) couples, so that prevent any form of discrimination.

The Polarization of the Coupling Strength of Interdependent Networks Stimulates Cooperation.

We introduce a mixed network coupling mechanism and study its effects on how cooperation evolves in interdependent networks. This mechanism allows some players (conservative-driven) to establish a fixed-strength coupling, while other players (radical-driven) adjust their coupling strength through the evolution of strategy. By means of numerical simulation, a hump-like relationship between the level of cooperation and conservative participant density is revealed. Interestingly, interspecies interactions stimulate polarization of the coupling strength of radical-driven players, promoting cooperation between two types of players. We thus demonstrate that a simple mixed network coupling mechanism substantially expands the scope of cooperation among structured populations.

Cosmology of a supercooled universe

First-order phase transitions (FOPTs) are ubiquitous in physics beyond the Standard Model (SM). Recently, models with no dimensionful parameters in the tree-level action have been attracting much attention because they can predict a very strong FOPT with ultra-supercooling. In this paper, we study the cosmological signatures of such a supercooling model. As a concrete model, we consider the SM with two additional real scalars $\phi$ and $S$, which can realize the electroweak symmetry breaking via Coleman-Weinberg mechanism. One of the additional scalars $S$ can naturally become a Dark Matter (DM) candidate due to the $Z_2^{}$ symmetry of the action. We study the FOPT of this model and calculate the Gravitational Wave (GW) signals and the thermal relic abundance of $S$ taking the filtered effects into account. Within the envelope approximation, we find that the GW peak amplitude can reach $\sim 10^{-10}$ around the frequency $f\sim 10^{-3}~$Hz for model parameters $(v_\phi^{},\lambda_{\phi S}^{})\sim (200~{\rm TeV},1.6)$ where $v_\phi^{}$ is the vacuum expectation value of $\phi$ and $\lambda_{\phi S}^{}$ is the scalar mixing coupling. On the other hand, the filtered DM mechanism only works for $0.8\lesssim \lambda_{\phi S}^{}\lesssim 1$, where the GW peak amplitude is found to be quite small $\lesssim 10^{-17}$.

A Compact Wideband Endfire Filtering Antenna Inspired by a Uniplanar Microstrip Antenna

This letter presents a design of a compact wideband endfire filtering antenna. The design starts from an endfire quasi-microstrip antenna, which is unidirectional with a smaller size when compared with a Yagi–Uda antenna. A reflector and a parasitic patch are utilized to introduce two new resonant frequencies to broaden the bandwidth. They also generate two radiation nulls at the lower band and the higher band, respectively. The endfire radiation mechanism can be modeled by a two-element antenna array. The mechanism of these two radiation nulls is explained by the mixed coupling theory. Therefore, the proposed antenna also shows filtering property without any extra circuits. In addition, a capacitive feeding structure is employed to improve the level of the reflection coefficient within the upper stopband. The measured results reveal that the proposed antenna has a bandwidth of 41.9% from 2.00 to 3.06 GHz and a peak gain of 7.3 dBi with an extremely small size of 0.105 λ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (λ is the wavelength at the center frequency). Two radiation nulls are observed at 1.78 and 3.19 GHz, respectively. The out-of-band roll-off of the antenna gain achieves 15 dB.

Search for dark photons using a multilayer dielectric haloscope equipped with a single-photon avalanche diode

We report on the results of the search for dark photons with mass around 1.5$\,\rm eV/c^2$ using a multilayer dielectric haloscope equipped with an affordable and commercially available photosensor. The multilayer stack, which enables the conversion of dark photons (DP) to Standard Model photons, is made of 23 bilayers of alternating SiO$_2$ and Si$_3$N$_4$ thin films with linearly increasing thicknesses through the stack (a configuration known as a "chirped stack"). The thicknesses have been chosen according to an optimisation algorithm in order to maximise the DP-photon conversion in the energy region where the photosensor sensitivity peaks. This prototype experiment, baptised MuDHI (Multilayer Dielectric Haloscope Investigation) by the authors of this paper, has been designed, developed and run at the Astroparticle Laboratory of New York University Abu Dhabi, which marks the first time a dark matter experiment has been operated in the Middle East. No significant signal excess is observed, and the method of maximum log-likelihood is used to set exclusion limits at $90\%$ confidence level on the kinetic mixing coupling constant between dark photons and ordinary photons.

Orientation-dependent Rashba spin-orbit coupling of two-dimensional hole gases in semiconductor quantum wells: Linear or cubic

Our recent study [Phys. Rev. B 103, 085309 (2021)] verified the existence of $\bf{k}$-linear Rashba spin-orbit coupling (SOC) of two-dimensional hole gases in quantum wells (QWs) which originates from a combination of heavy-hole-light-hole (HH-LH) mixing and direct dipolar coupling to the external electric field. However, the Rashba SOC dependence on QW orientations remains unclear. Here, we explore this dependence on QW orientations and uncover an upper and lower bound to the orientation-dependent $\bf{k}$-linear Rashba SOC along the [110]- and [111]- crystalline directions by performing atomistic pseudopotential calculations associated with theoretical analysis. The intrinsic HH-LH mixing at the Brillouin zone center, maximal in [110]-oriented quantum wells and minimal in [111]- and [001]-oriented QWs, plays an essential role. Remarkably, we find that only $\bf{k}$-cubic Rashba SOC exists in [111]-oriented QWs. These findings help understand the physical mechanism of the Rashba SOC dependence on QW orientations and provide a strategic prediction for experiments to realize the large Rashba SOC.

Tunable balanced bandpass filter with wide frequency‐tuning range and high selectivity

AbstractA tunable balanced bandpass filter (BPF) with a wide frequency‐tuning range (FTR) and high selectivity is presented. The designed BPF is implemented by utilizing varactor‐tuned square ring resonators (SRRs) with parallel‐coupled feedlines. A wide FTR with an almost constant absolute bandwidth (CABW) can be realized by varactors Cv2 connected between SRRs. Four transmission zeros (TZs) can be obtained by the mixed electric and magnetic coupling, source‐load (S‐L) frequency‐variant coupling, and four shunt quarter‐wavelength open and short stubs. Meanwhile, two TZs on both sides of the passband keep the relative position unchanged to achieve high selectivity. The other two are generated to improve the out‐band rejection. In addition, by employing additional stubs and capacitances on the symmetry plane, the common‐mode (CM) suppression can be enhanced. For verification, a tunable balanced BPF with 0.62‐1.27 GHz and four TZs was designed, manufactured, and tested. And experimental results agree well with the simulated ones.

Flux-based modeling of heat and mass transfer in multicomponent systems

In the present work, the macroscopic governing equations governing the heat and mass transfer for a general multicomponent system are derived via a systematic nonequilibrium thermodynamics framework. In contrast to previous approaches, the relative (with respect to the mass average velocity) component mass fluxes (relative species momenta) and the heat flux are treated explicitly, in complete analogy with the momentum flux. The framework followed here, in addition to allowing for the description of relaxation phenomena in heat and mass transfer, establishes to the fullest the analogy between all transport processes, momentum, heat, and mass transfer, toward which R. B. Bird contributed so much with his work. The inclusion of heat flux-based momentum as an additional variable allows for the description of relaxation phenomena in heat transfer as well as of mixed (Soret and Dufour) effects, coupling heat and mass transfer. The resulting models are Galilean invariant, thereby resolving a conundrum in the field, and always respect the second law of thermodynamics, for appropriate selection of transport parameters. The general flux-based dynamic equations reduce to the traditional transport equations in the limit when mass species and heat relaxation effects are negligible and are fully consistent with the equations established from the application of kinetic theory in the limit of dilute gases. As an added benefit, for the particular example case of hyperbolic diffusion we illustrate the application of the proposed models as a method to allow the use of powerful numerical solvers normally not available for solving mass transfer models more generally.

High-Selectivity Bandpass Filter with Controllable Attenuation Based on Graphene Nanoplates.

A high-selectivity band pass filter with controllable attenuation based on graphene nanoplates is proposed in this paper. Graphene with controllable resistance has a good uniform attenuation effect to electric field intensity. The filter utilizes quarter wavelength stepped impedance resonators and mixed electromagnetic coupling to have compact circuits and high performance. The graphene nanoplates are loaded on the microstrip resonator to reduce the electric field intensity, which results in a flat attenuation in the passband. In addition, the filter has two transmission zeros, which lead to a strong selectivity. Finally, a high-selectivity bandpass filter with controllable attenuation is formed. By changing the bias voltage of graphene, a controllable attenuation of 1.64–11.13 dB can be achieved in the working passband centered at 1.36 GHz. In order to validate the concept, the prototype is fabricated and measured. The measurement results are in good agreement with the simulation results. The proposed high-selectivity bandpass filter with controllable attenuation based on graphene nanoplates has widely potential in reconfigurable wireless communication systems and radar systems due to its high integration and versatility.

A high‐performance empty substrate integrated waveguide filter with mixed electric and magnetic coupling

AbstractAn empty substrate integrated waveguide (ESIW) bandpass filter with enhanced electric and magnetic coupling is proposed in this letter. ESIW uses the air as dielectric in order to reduce the dielectric loss caused by usual medium materials. However, the existence of air cavities requires at least three layers of structure, which greatly increases the difficulty of designing complex circuits with high‐performance and multiple requirements. The proposed mixed coupling structure creates the finite transmission zeros based on ESIW technology for the first time, which makes it possible to realize complex high‐performance circuits with ESIW technology. Taking advantage of the multilayer structure of the ESIW, the proposed cross‐coupling is conveniently realized with higher frequency selectivity and lower insertion loss while maintaining the substrate of three layers and the self‐encapsulation characteristics of ESIW. A fourth‐order filter with an H‐shaped slot line on the top metal plane of two adjacent air cavities is produced. A good agreement between the measurements and simulations indicates that the proposed filter achieves an insertion loss as low as 0.7 dB and the 6.1% bandwidth at 9.85‐GHz X band. It demonstrates the improvement of insertion loss and frequency selectivity, which lays a foundation for the design of complex microwave devices.