Planar Topology Research Articles

Surrogate-Assisted Differential Evolution for the Design of Multimode Resonator Topology.

The microstrip devices based on multimode resonators represent a class of electromagnetic microwave devices, promising use in tropospheric communication, radar, and navigation systems. The design of wideband bandpass filters, diplexers, and multiplexers with required frequency-selective properties, i.e., bandpass filters, is a complex problem, as electrodynamic modeling is a time-consuming and computationally intensive process. Various planar microstrip resonator topologies can be developed, differing in their topology type, and the search for high-quality structures with unique frequency-selective properties is an important research direction. In this study, we propose an approach for performing an automated search for multimode resonators' conductor topology parameters using a combination of evolutionary computation approach and surrogate modeling. In particular, a variant of differential evolution optimizer is applied, and the model of the target function landscape is built using Gaussian processes. At every iteration of the algorithm, the model is used to search for new high-quality solutions. In addition, a general approach for target function formulation is presented and applied in the proposed approach. The experiments with two microwave filters have demonstrated that the proposed algorithm is capable of solving the problem of tuning two types of topologies, namely three-mode resonators and six-mode resonators, to the required parameters, and the application of surrogated-assisted algorithm has significantly improved overall performance.

Two-loop integrals for tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document}+jet production at hadron colliders in the leading colour approximation

We compute the differential equations for the two remaining integral topologies contributing to the leading colour two-loop amplitudes for pp → tt¯j\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t}j $$\\end{document}. We derive differential equations for the master integrals by solving the integration-by-parts identities over finite fields. Of the two systems of differential equations, one is presented in canonical ‘d log’ form, while the other is found to have an elliptic sector. For the elliptic topology we identify the relevant elliptic curve, and present the differential equations in a more general form which depends quadratically on ε and contains non-logarithmic one-forms in addition to the canonical d log’s. We solve the systems of differential equations numerically using generalised series expansions with the boundary terms obtained using the auxiliary mass flow method. A summary of all one-loop and two-loop planar topologies is presented including the list of alphabet letters for the ‘d log’ form systems and high-precision boundary values.

3D analytical magnetic model calculation for Halbach PM induction heater planar topology

In this work, a 3D analytical magnetic model based on hybridation of the sub-domain’s method and the image’s theory to compute magnetic field and translational motion eddy current in the conducting plate of the Halbach permanent magnet induction heater planar topology is developed. The main objective is to remedy the problem of the transverse edge effect, and hence improving the efficiency of analytical model and the accuracy of results. The developed model also allows fast and precise simulations of 3D magnetic phenomena, and presents an important reduction in computation time compared to 3D finite element simulations.

Wideband bandpass filter with ultra-wide stopband based on cross-shaped parallel coupled lines

A broadband out-of-band rejection capability and multiple transmission zeros of wideband bandpass filter are proposed and validated in this article, which employ quadruple anti-parallel coupled-line structures to form a novel cross-shaped resonator planar topology. The centered frequency of the single wideband bandpass filter designed for verification is located at 2.4 GHz (f 0) with a fractional bandwidth of 50%. The interaction of crossed multiple anti-coupled lines with a lowpass-loaded fan constitutes the wideband with nine transmission zeros in the 5 f 0 frequency range for improved suppression extending to 26.5 GHz (10.7 f 0) with a suppression level of 12.5 dB. Moreover, the designed prototype filter is implemented and tested with a measured minimum insertion loss of 0.9 dB. Good agreement between the measured and simulated results is attained to successfully validate the correctness of the proposed design approach.

Coupled connectivity in the global complex network: the case of United Kingdom (1880–1925)

The main objective of this research is to analyse the connectivity of cities in a coupled network composed of planar (railways) and non-planar (maritime) topologies. It examines the state of the network during the 1880–1925 period, namely in the context of the first globalization wave (1880–1914), when trade and urban development were closely tied to progress in communications systems and steam propulsion especially. Edges represent intercity physical infrastructure on land, and inter-port ship voyages at sea. We tested several hypotheses in terms of inter-network specialisation and urban hierarchies with an application in the United Kingdom. The main results reveal that the networks are highly interdependent, whereas combined centrality is closely associated with city size and urban growth. We discuss the key results in light of network science, spatial science, maritime history, and transport research.

Design and demonstration of an ultra-thin planar microscale capillary pumped loop for electronics thermal management

With new requirements for enhanced thermal management, the minimum size of modern compact electronic devices and the maximum allowable processing speeds of the underlying microprocessor chips have become fundamentally limited by Joule heating. Miniaturizing a conventional loop heat pipe (LHP) or capillary pumped loop (CPL) to enable an ultra-thin high-heat-flux thermal transport system can lead to a paradigm shift in electronics thermal management. However, the complex thermodynamics of a CPL flow loop and the altered behavior of surface tension forces and thermal transport effects at small length scales pose several challenges to the actual implementation of a planar microscale CPL. Here we report on the design aspects of a micro-CPL device fabricated on a 500μm-thick silicon wafer, and experimentally examine the process of evaporation and two-phase flow in the device. An optical study of liquid evaporation in two distinct planar evaporator topologies during device startup reveals the critical roles played by enhanced surface tension forces and increased parasitic heat flows. Critical microfluidic device design aspects that can ensure the successful startup and operation of these ultra-thin thermal management devices are thereby revealed. Device evaporation experiments reveal successful device startup under evaporative heat fluxes of 10–20 W/cm2.

Independently controlled multifrequency rejection bands in a broadband filter design using shorted T-shaped stub loaded resonator with central square ring

This article discusses the development and analysis of a broadband filter capable of suppressing specific frequencies of wireless applications at 4.7 GHz for WLAN, 8.3 GHz, and 11.5 GHz (for satellite communication) by combining a T-shaped stub loaded resonator with a central square ring to achieves high performance and compact size within the bandwidth of interest. The filter achieves low signal loss of 0.4 dB across the entire passband of 14.9 GHz bandwidth, good reflection suppression exceeding 10 dB, and independently adjustable multi stopbands. It utilizes a simple planar topology for a small footprint of 0.52 λg × 0.32 λg, where λg represents the wavelength at 4.7 GHz. The proposed filter evaluated using classical method an even-odd-mode analysis, and a 3D software tool HFSS-15 is used for simulations. The physical prototype is built on a Rogers RO-4350 substrate using LPKF S63 ProtoLaser machine. To confirm the accuracy and performance of the prototype, measurements were conducted using a ZNB20 vector network analyser. The simulations and measurement results confirm its effectiveness, paving the way for applications in various fields such as radar systems, medical imaging, and wireless communication.

Ionic Thermoelectric Generators in Vertical and Planar Topologies Based on Fluorinated Polymer Hybrid Materials with Ionic Liquids.

Ionic thermoelectrics (TEs), in which voltage generation is based on ion migration, are suitable for applications based on their low cost, high flexibility, high ionic conductivity, and wide range of Seebeck coefficients. This work reports on the development of ionic TE materials based on the poly(vinylidene fluoride-trifluoroethylene), Poly(VDF-co-TrFE), as host polymer blended with different contents of the ionic liquid, IL, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI]. The morphology, physico-chemical, thermal, mechanical, and electrical properties of the samples are evaluated together with the TE response. It is demonstrated that the IL acts as a nucleating agent for polymer crystallization. The mechanical properties and ionic conductivity values are dependent on the IL content. A high room temperature ionic conductivity of 0.008 S cm-1 is obtained for the sample with 60 wt% of [EMIM][TFSI] IL. The TE properties depend on both IL content and device topology-vertical or planar-the largest generated voltage range being obtained for the planar topology and the sample with 10 wt% of IL content, characterized by a Seebeck coefficient of 1.2 mV K-1. Based on the obtained maximum power density of 4.9 µW m-2, these materials are suitable for a new generation of TE devices.

Biomimetic Design of a New Semi-Rigid Spatial Mesh Antenna Reflector.

The reflective surface accuracy (RSA) of traditional space mesh antennas typically ranges from 0.2 to 6 mmRMS. To improve the RSA, an active control scheme can be employed, although it presents challenges in determining the installation position of the actuator. In this study, we propose a novel design for a semi-rigid cable mesh that combines rigid members and a flexible woven mesh, drawing inspiration from both rigid ribbed antennas and biomimicry. Initially, we investigate the planar mesh topology of spider webs and determine the bionic cable surface's mesh topology based on the existing hexagonal meshing method, with RSA serving as the evaluation criterion. Subsequently, through motion simulations and careful observation, we establish the offset angle as the key design parameter for the bionic mesh and complete the design of the bionic cable mesh accordingly. Finally, by analyzing the impact of the node quantity on RSA, we determine a layout scheme for the flexible woven mesh with a variable number of nodes, ultimately settling for 26 nodes. Our results demonstrate that the inclusion of numerous rigid components on the bionic cable mesh surface offers viable installation positions for the actuator of the space mesh antenna. The reflector accuracy achieved is 0.196 mmRMS, slightly surpassing the lower limit of reflector accuracy observed in most traditional space-space mesh antennas. This design presents a fresh research perspective on combining active control schemes with reflective surfaces, offering the potential to enhance the RSA of traditional rigid rib antennas to a certain extent.

PdMo bimetallene nanozymes for photothermally enhanced antibacterial therapy and accelerated wound healing.

Although antibacterial platforms involving nanozymes have been extensively investigated, there are still problems of poor reactive oxygen species generation efficiency and obstinate bacterial biofilms. Developing a nanozyme-photothermal therapy nanoplatform with superior sterilization effects and minimal side effects would be a good alternative for completely eliminating bacteria and biofilms. Herein, an ultrathin PdMo bimetallene nanozyme with a planar topology and boosted metal utilization, exhibiting excellent photothermal and peroxidase-like activity, is designed for synergistic nanozyme-photothermal sterilization applications and accelerated wound healing. The superior catalytic activity of PdMo bimetallene nanozymes could convert a biosafe concentration of hydrogen peroxide (H2O2) into large quantities of toxic hydroxyl radicals (•OH) under laser irradiation, enhancing bacterial membrane permeability and thermal sensitivity for efficient removal of bacteria and biofilms. In addition, PdMo bimetallene presents a good wound-healing ability according to the results of fibroblast proliferation and collagen deposition with minor side effects. This work would provide an innovative avenue for developing metallene-based nanozymes for biomedical applications.

Nonlinear regimes of spin wave propagation in a waveguide with a one-dimensional hole array

Purpose. Investigation of spin-wave signal passage in a system of magnetic microwaves separated from each other by a one-dimensional array of holes. Using numerical and experimental methods to show controlled spatial-frequency selection of the signal in linear and nonlinear modes of operation. Methods. Micromagnetic modeling of the spatial intensity distributions of spin waves. Obtaining S-parameters of spin waves propagating in a tangentially magnetized structure using a vector circuit analyzer. Results. The spatially selective properties of the structure in linear and nonlinear modes are demonstrated using micromagnetic modeling. A mechanism for controlling the frequency range of the Bragg zone is revealed using a vector analyzer. Conclusion. The proposed structure can be used as a functional element in planar topologies of magnon networks and parallel signal processing devices based on them.

GENERATING LIGHTWEIGHT BUILDING MODELS WITH PRESERVED STRUCTURAL FEATURES FROM NOISY 3D MESHES

Abstract. Obtaining building instance models directly through photogrammetry and other means results in high polygon counts and structural detail levels. Therefore, it is an important challenge to preserve the features of instant building models and generate lightweight building models from them. In this paper, we propose an improved lightweight reconstruction method for 3D building models based on planar primitives extraction, topology correction, and optimal planes selection. Improvements due to our method arise from three aspects: (1) After plane segmentation based on a simple region growing method, a second plane segmentation is performed on the building model based on the similarity of normal vectors. (2) According to the building structural characteristics, the initial plane segmentation is checked to generate new plane regions within the necessary connection regions. (3) The intersection of candidate planes is improved by enlarging the region of candidate faces, and the topological connection is improved. Furthermore, the topological relations of all planar primitives that have been optimized are recorded in an undirected graph. Finally, a watertight and manifold lightweight model is extracted from the faces of a candidate set by energy minimization. Experiments on different data sets show that the improved method is more reasonable in plane segmentation, and has superior performance in algorithm robustness and necessary structure recovery of buildings. Even when dealing with imperfect data, a watertight model is still obtained.

A Whirling Dervish: Polynomial-Time Algorithm for the Regional SRLG-Disjoint Paths Problem

The current best practice in survivable routing is to compute link or node disjoint paths in the network topology graph. It can protect single-point failures; however, several failure events may cause the interruption of multiple network elements. The set of network elements subject to potential failure events is called Shared Risk Link Group (SRLG), identified during network planning. Unfortunately, for any given list of SRLGs, finding two paths that can survive a single SRLG failure is NP-Complete. In this paper, we provide a polynomial-time SRLG-disjoint routing algorithm for planar network topologies and a large set of SRLGs. Namely, we focus on regional failures, where the failed network elements must not be far from each other. We use a flexible definition of regional failure, where the only restrictions are that i) the topology is a planar graph, ii) each SRLG forms a set of connected edges in the dual of the planar graph, and iii) for each node <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$v$</tex-math> </inline-formula> , the links incident to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$v$</tex-math> </inline-formula> are part of an SRLG. The proposed algorithm is based on a max-min theorem. Through extensive simulations, we show that the algorithm scales well with the network size, and one of the paths returned by the algorithm is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4$</tex-math> </inline-formula> % longer than the shortest path on average.

Ultrasonic neural regulation over two-dimensional graphene analog biomaterials: Enhanced PC12 cell differentiation under diverse ultrasond excitation

Two-dimensional (2D) biomaterials, with unique planar topology and quantum effect, have been widely recognized as a versatile nanoplatform for bioimaging, drug delivery and tissue engineering. However, during the complex application of nerve repair, in which inflammatory microenvironment control is imperative, the gentle manipulation and trigger of 2D biomaterials with inclusion and diversity is still challenging. Herein, inspired by the emerging clinical progress of ultrasound neuromodulation, we systematically studied ultrasound-excited 2D graphene analogues (graphene, graphene oxide, reduced graphene oxide (rGO) and carbon nitride) to explore their feasibility, accessibility, and adjustability for ultrasound-induced nerve repair in vitro. Quantitative observation of cell differentiation morphology demonstrates that PC12 cells added with rGO show the best compatibility and differentiation performance under the general ultrasound mode (0.5 w/cm2, 2 min/day) compared with graphene, graphene oxide and carbon nitride. Furthermore, the general condition can be improved by using a higher intensity of 0.7 w/cm2, but it cannot go up further. Later, ultrasonic frequency and duty cycle conditions were investigated to demonstrate the unique and remarkable inclusion and diversity of ultrasound over conventional electrical and surgical means. The pulse waveform with power of 1 MHz and duty cycle of 50 % may be even better, while the 3 MHz and 100 % duty cycle may not work. Overall, various graphene analog materials can be regarded as biosafe and accessible in both fundamental research and clinical ultrasound therapy, even for radiologists without material backgrounds. The enormous potential of diverse and personalized 2D biomaterials-based therapies can be expected to provide a new mode of ultrasound neuromodulation.

Structural evolution, stability, electronic and bonding properties of sodium-doped magnesium cluster cations

Bimetallic sodium-doped magnesium cluster cations, NaMg n + (n= 2–12), have been investigated through a synergetic combination of the CALYPSO code and DFT calculations. The results reveal that the lowest-energy structures of NaMg n + exhibit linear, planar, triangular pyramid, pentagonal pyramid, and triangular prism topologies. The structures can be described as a substituted geometry of pure Mg clusters at the small size. Starting from n = 9, the dominant structures transform into a triangular prism-based configuration. Like anionic and neutral NaMg n clusters, the Na atom prefers the peripheral regions of the Mg n framework. Stability studies indicate NaMg4 + and NaMg10 + to be the~most stable clusters, which may benefit from their closed-shell electron structures. Analysis of the bonding nature shows stronger Mg-Mg interaction than the Na-Mg interaction in the NaMg4 + and NaMg10 + clusters. The reason is that covalent bonds are formed in the Mg-Mg regions, while there is no aggregation of electron density in the Na-Mg regions.

Comparison of Terahertz Transceiver Array Topologies in Multiobject Imaging

We investigate the effect of side lobe level (SLL) and multipath propagation in millimeter-wave(mmWave) and terahertz (THz) imaging systems for various transceiver array topologies. This work considers practical limitations in high-resolution active imaging systems and focuses on electrically large, planar antenna array topologies. As such, we investigate the imaging performance of sparse transmitting/receiving (Tx/Rx) array topologies that enable high angular/spatial resolution imaging with minimum hardware complexity. We show that 1) properly tapering the sparse array excitation can mitigate image clutter caused by high side lobes and 2) sparse arrays are more vulnerable to multipath reflections and clutter in dense scenes with highly reflective surfaces. We present both full-wave numerical analysis and laboratory experiments (250-300 GHz) to verify and compare the imaging array performance for several exemplary scenes.

Multi Frequency Controllable In-Band Suppressions in a Broad Bandwidth Microstrip Filter Design for 5G Wi-Fi and Satellite Communication Systems Utilizing a Quad-Mode Stub-Loaded Resonator

The key elements used for receiving and processing signals in communication systems are the bandpass filters. Initially, a common operating mechanism was applied for the design of broadband filters, i.e., by cascading low-pass filters or high-pass filters using multiple line resonators with length quarter-half- or full-wavelength with central frequency, but using these approaches, the design topology becomes expensive and complex. The above mechanisms can be possibly overcome using a planar microstrip transmission line structure due to its simple design fabrication procedure and low cost. So, pointing out the above problems in bandpass filters such as low-cost, low insertion loss, and good out-of-band performance, this article presents a broadband filter with multifrequency suppression capability at 4.9 GHz, 8.3 GHz, and 11.5 GHz using a T-shaped shorted stub-loaded resonator with a central square ring coupled to the basic broadband filter. Initially, the C-shaped resonator is utilized for the formation of a stopband at 8.3 GHz for a satellite communication system, and then a shorted square ring resonator is added to the existing C-shaped structure for the realization of two more stopbands at 4.9 GHz and 11.5 GHz for 5G (WLAN 802.11j) communication, respectively. The overall circuit area covered with the proposed filter is 0.52 λg × 0.32 λg (λg is the wavelength of the feed lines at frequency 4.9 GHz). All the loaded stubs are folded in order to save the circuit area, which is an important requirement of next-generation wireless communication systems. The proposed filter has been analyzed using a well-known transmission line theory, even–odd-mode, and simulated with the 3D software HFSS. After the parametric analysis, some attractive features were obtained, i.e., compact structure, simple planar topology, low insertion losses of 0.4 dB over the entire band, good return loss greater than 10 dB, and independently controlled mutli stopbands, which make the proposed design unique and can be used in various wireless communication system applications. Finally, a Rogers RO-4350 substrate is selected for the fabrication of the prototype using an LPKF S63 ProtoLaser machine and then measured using a ZNB20 vector network analyzer for matching the simulated and measured results. After testing the prototype, a good agreement was found between the results.

Analysis of On-Antenna Power Combining for Realization of Pattern-Reconfigurable Multifeed Microstrip Antennas

This article explores an on-antenna power combining concept for multifeed microstrip antennas. We incorporated different radiation modes of multifeed antennas, thereby optimally exploiting the given space of a single radiator. The analytical cavity model is revisited to facilitate analysis of the on-antenna power combining mechanism in planar topologies. The analytical modeling is first aimed to apply to conventional patch structures and offers an in-depth design methodology. As the analytical method is facing limitations in irregular-shaped antennas we proposed a reliable and computationally cheap numerical method based on the eigenvalue analysis of the scattering matrix. The proposed method can be used to extract the optimum excitation and impedance of each port of resonant-type multifeed antennas. Due to the proposed numerical method, one can examine the excitation vector and the active impedance values for different radiation modes of multifeed antenna concurrently. Next, the reliability of the solutions of the proposed numerical method is evaluated against the analytical solutions through some examples. A multifeed structure not only can furnish on-antenna power combining but also assist with tailoring reconfigurable antennas. Finally, a practical planar radiator topology featuring multifeed excitations exhibiting a high-gain reconfigurable antenna with sum and difference patterns is devised.

A Robust Fault-Tolerance Scheme with Coverage Preservation for Planar Topology Based WSN

A Robust Fault-Tolerance Scheme with Coverage Preservation for Planar Topology Based WSN

Two-loop master integrals for a planar topology contributing to pp → toverline{t}j

We consider the case of a two-loop five-point pentagon-box integral configuration with one internal massive propagator that contributes to top-quark pair production in association with a jet at hadron colliders. We construct the system of differential equations for all the master integrals in a canonical form where the analytic form is reconstructed from numerical evaluations over finite fields. We find that the system can be represented as a sum of d-logarithmic forms using an alphabet of 71 letters. Using high precision boundary values obtained via the auxiliary mass flow method, a numerical solution to the master integrals is provided using generalised power series expansions.