Uniform Line Research Articles

Experimental evaluation of a universal covariance matrix tapered adaptive beamformer

Covariance Matrix Tapers (CMT) widen the beampattern notches of an adaptive beamformer to improve the suppression of moving interferers. If the bearing rate of a moving interferer is known, then the ideal notch width can be found. In practice, the bearing rate is an unknown and often time-varying parameter. To address this challenge, we previously proposed a universal CMT beamformer that blends the array weights across a set of fixed notch width CMT beamformers. This universal beamformer suppressed moving interferers well in simulations. This talk presents experimental results from a 31 microphone uniform line array with a 750 Hz moving interferer at a range of 10 meters. We evaluated two scenarios with the interferer moving at different speeds. In the first experiment, the interferer moved 40deg in 814 snapshots (approximately 0.05 deg/snapshot) while in the second experiment, the interferer moved 30° in the same time. Both experiments had 25 dB INR at a single sensor. The experiments confirm that the universal CMT beamformer adapts to the best notch width for moving interferers. The results also show that the universal beamformer matches or exceeds the performance of the best fixed notch width CMT beamformer. [Work supported by ONR 321US.]

Ink Formulation and Optimum Surface Condition for a Printed Organic Light-Emitting Diode with High Boiling Point and Surface Tension Solvents

Ink formulation with the benzoate-type solvent mixture was designed to provide a mismatch in the surface tension, boiling point, and viscosity toward a stable jet printing on organic light-emitting diode (OLED) pixel pattern cell. Compared with a single component solvent ink, the mixtures showed smoother surface roughness and uniform line printed, while the dried film roughness was further improved by solvent-vapor annealing. Inkjet OLEDs on the 60 to 80 μm-scale pixels were fabricated, and the luminous quantum efficiency behavior of the printed OLEDs were characterized in terms of structural perfection of patterns and in-pixel coverage for different bank boundaries. With the optimum printing recipe and pattern-receptor surface condition, an external quantum efficiency of inkjet device was more than 82% of the value for spin-coating reference.

An EH₀-Mode Microstrip Leaky Wave Antenna on Differentially Excited Coupled Line for Transversal Single-Beam Radiation

This communication presents a method to make the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode microstrip leaky wave antenna (MLWA) radiate single beam in its transversal plane based on the differentially excited coupled microstrip line structure with low cross-polarization. The conventional EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode MLWA is constructed by periodically loading a series of shorting pins along the center line of the uniform line, but it mainly radiates dual beams in its transversal plane. If a ground plane approaches to one of its edges with rotation of the whole structure, only one radiation aperture will be left to radiate single beam in the broadside direction. Herein, a planar differentially excited coupled line configuration is implemented to validate the proposed method and simultaneously inherits the original outstanding characteristic of freely designed narrow strip width. In design, a unified equivalent model is first established to provide insight into its radiation principle through propagation characteristics. Then, the dispersion and radiation properties are further investigated under mixed geometrical parameters. Finally, a prototype MLWA with transversal single-beam radiation is designed and fabricated with good agreement between the simulated and measured results, which validates the proposed method for designing a single-beam EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> mode MLWA.

An Extension of the Guided Wave M‐Component Model Taking Into Account the Presence of a Tall Strike Object

AbstractWe present in this paper an extension of the guided‐wave M‐component model of Rakov et al. considering the presence of a vertically elevated strike object. The tall object is represented as a lossless, uniform transmission line. Expressions for the current distribution along the channel and along the strike object are derived. Simulation results for the electric field at close (100 m), intermediate (15 km), and far (100 km) distance ranges are presented, considering fast and slow M‐component currents. The results show that, for very tall structures and fast M‐component waves, the presence of a tall strike object can result in a sharp peak superimposed on the M‐component electric field at intermediate and far distance ranges (e.g., 15 and 100 km). At close distances, the electric field of a fast M‐component is characterized by an initial negative excursion followed by a polarity change. It is shown that the presence of the tower results in a decrease of the negative initial excursion of the field. For slow M‐component waveforms or for moderately tall structures, the presence of the tall strike object can be disregarded in the M‐component field calculations. A discussion on the influence of the M‐wave channel height and velocity on the electric fields for fast M‐component currents is also presented. The study suggests a noticeable effect of the M‐wave velocity on the electric fields at all distance ranges. The variations of the wave velocity and channel length affect the time of appearance of the superimposed sharp peak on the electric fields. However, the sharp peak magnitude, which is due to the presence of the tower, is independent of the channel length and wave velocity. It is determined by the injected current and the reflection coefficients from the ground and tower top.

Generative design of stiffened plates based on homogenization method

Stiffened plates are widely used in aerospace structures as load-bearing components. In order to obtain a novel design of stiffened structures with excellent performance, a generative design method of stiffened plates (GDMSP) based on the homogenization method is proposed in this paper, which optimizes the stiffener layout based on an equivalent model. Then, the detailed model can then be obtained by extracting the stiffener path from the discrete distribution of stiffener angles. Moreover, the optimized design can be obtained by size optimization based on the detailed model. Two examples are used to illustrate the proposed framework, including the stiffness maximization of a rectangle stiffener plate and the buckling load maximization of a square stiffener plate. The optimized stiffener configurations are characterized by streamlines and uniform lines, respectively. For the first example, the stiffness of the stiffener design has an improvement of 17%. For the second example, the optimized design improves the buckling load by 35%. Results indicate that the proposed method can effectively provide a novel generative design for stiffened plates. Moreover, the obtained results have a clear stiffener path and have a noticeable improvement in performance, which can be directly used to establish a detailed model.

Direct Fabrication of Micron-Thickness PVA-CNT Patterned Films by Integrating Micro-Pen Writing of PVA Films and Drop-on-Demand Printing of CNT Micropatterns.

The direct fabrication of micron-thickness patterned electronics consisting of patterned PVA films and CNT micropatterns still faces considerable challenges. Here, we demonstrated the integrated fabrication of PVA films of micron-thickness and CNT-based patterns by utilising micro-pen writing and drop-on-demand printing in sequence. Patterned PVA films of 1–5 μm in thickness were written first using proper micro-pen writing parameters, including the writing gap, the substrate moving velocity, and the working pressure. Then, CNT droplets were printed on PVA films that were cured at 55–65 °C for 3–15 min, resulting in neat CNT patterns. In addition, an inertia-pseudopartial wetting spreading model was established to release the dynamics of the droplet spreading process over thin viscoelastic films. Uniform and dense CNT lines with a porosity of 2.2% were printed on PVA substrates that were preprocessed at 55 °C for 9 min using a staggered overwriting method with the proper number of layers. Finally, we demonstrated the feasibility of this hybrid printing method by printing a patterned PVA-CNT film and a micro-ribbon. This study provides a valid method for directly fabricating micron-thickness PVA-CNT electronics. The proposed method can also provide guidance on the direct writing of other high-molecular polymer materials and printing inks of other nanosuspensions.

EVALUATION OF THE GENETIC HOMOGENEITY OF THE SUGAR BEET LINES USED AS SOURCES IN HYBRID PRODUCTION

Currently, efforts in sugar beet selection are aimed mainly at the creation of highly productive hybrid combinations which could be repeatedly derived from source line material. Naturally, the important step in this process is the development of constant homozygous source lines with high combining ability. Traditional approach in development of uniform sugar beet lines is based on repeated selection of self-pollinated lines. However, biennial lifecycle, cross-incompatibility and inbreeding depression all make breeding and maintaining the genetic homogeneity of sugar beet a challenging endeavor. To increase efficiency of development and preservation of genetic homogeneity of sugar beet lines used in hybrid production at the LLP “KazSRIA&amp;PG”, our biotechnology lab started working on introduction of DNA markers into the selection process. Twenty sugar beet lines of various origins and levels of ploidy from LLP “KazSRIA&amp;PG” collection have been studied, to assess their genetic homogeneity, using three SSR markers: Bvv21, Bvv53 and Bvv.

Development of an analytical method to determine the propagation characteristics of microstrip line on artificial perforated substrates

This paper presents an analytical method to investigate the propagation characteristics of a uniform microstrip line placed on porous substrates. The structure is periodic with a specified unit cell and the substrate is made of cascaded multi-layer dielectric slabs. The proposed method is started by solving wave equation by decomposing Helmholtz operator using appropriate eigen-functions and applying the associated boundary conditions of tangential electromagnetic fields of the unit cell. Then, using Floquet theorem, the equivalent propagation constant of a one-dimensional (1-D) periodic structure is obtained. In addition to, the proposed method is developed for two-dimensional (2-D) structures by a suitable transformation. Several practical structures are considered to verify the accuracy of the proposed method. The comparison of the proposed analytical model and measurement results and those obtained using simulation process provided by High Frequency Simulator Strctures (HFSS) are reported. It is shown that our method can be used for a wide variety of structures to quickly estimate the required parameters with a good accuracy.

Research on Fault Location of Distribution Lines Based on the Standing Wave Principle

Aiming at the fast and accurate location of a single-phase ground fault in the distribution network, a single terminal injection signal location method, based on the standing wave principle, is proposed. Firstly, the double conductor standing wave principle formation, based on uniform transmission line theory, is analyzed, and the mathematical model of the fault distance algorithm is established. Secondly, a fault detection circuit is built by simulation, and the distribution trend of the standing wave and its relationship with unit capacitance and unit inductance are studied. By setting the source signal frequency and detection point interval and other parameters, the fault location of this method under direct grounding fault and through grounding resistance fault is simulated and studied. Finally, the fault distance is calculated and located by an experiment. The results show that the positioning accuracy is high, which verifies the effectiveness of the standing wave positioning method.

Generalized Radon transform approach to target motion parameter estimation using a stationary underwater vector hydrophone.

Underwater platforms provide long-term detection of undersea targets. In this paper, we propose a method for the estimation of target motion parameters by submerged static acoustic detection equipment. The proposed method is based on the Radon transform of modeling the target moving in a uniform straight line. The heading angle, the time to the closest point of approach (CPA), and the ratio of velocity to the horizontal range of the target at the CPA to the sensor are obtained by applying the generalized Radon transform (GRT) to bearing-time records. The velocity of the target is determined by applying the GRT to the line-spectrum-time records. Furthermore, the motion trajectory of the target with respect to the detection equipment can be calculated from the above parameters. To validate the feasibility and performance of the proposed method, computer simulations and sea trials based on a fixed single vector measurement system were analyzed in this paper. The results suggest that the proposed method can accurately estimate the motion parameters and can calculate the trajectory of the moving vessel along a straight line at constant velocity.

Evolution of field line helicity in magnetic relaxation

Plasma relaxation in the presence of an initially braided magnetic field can lead to self-organization into relaxed states that retain non-trivial magnetic structure. These relaxed states may be in conflict with the linear force-free fields predicted by the classical Taylor theory, and remain to be fully understood. Here, we study how the individual field line helicities evolve during such a relaxation, and show that they provide new insights into the relaxation process. The line helicities are computed for numerical resistive-magnetohydrodynamic simulations of a relaxing braided magnetic field with line-tied boundary conditions, where the relaxed state is known to be non-Taylor. First, our computations confirm recent analytical predictions that line helicity will be predominantly redistributed within the domain, rather than annihilated. Second, we show that self-organization into a relaxed state with two discrete flux tubes may be predicted from the initial line helicity distribution. Third, for this set of line-tied simulations we observe that the sub-structure within each of the final tubes is a state of uniform line helicity. This uniformization of line helicity is consistent with Taylor theory applied to each tube individually. However, it is striking that the line helicity becomes significantly more uniform than the force-free parameter.

Analysis of multiconductor transmission lines using the time domain method of lines

In this study, the solution of lossy multiconductor transmission lines is obtained using the numerical Time Domain Method of Lines (TDMoL). The TDMoL algorithm comprises discretizing a differential equation in the spatial dimensions and using an analytical solution in the time domain. This leads to high numerical accuracy compared with full-discretizing finite difference techniques which require a significant computational time and extensive memory. In addition, investigation of the numerical dispersion characteristics of the single and multiconductor lossy and lossless transmission lines engenders a time independent relation which proves the unconditionally stability and nondispersive property of the method. To examine the accuracy of the TDMoL, three different structures including a three-coupled uniform transmission line, a nonuniform coupled transmission line and a lossy interconnect with dynamic and functional crosstalk are evaluated. The results of the proposed methodology are validated by those of leap-frog finite difference time domain (LF-FDTD) method and ADS commercial software, and reveals up to 90% reduction in CPU time while maintaining the same degree of accuracy.

Broadband Sheet Parametric Oscillator for χ (2) Optical Frequency Comb Generation via Cavity Phase MatchingSupported by the National Key Research and Development Program of China (Grant Nos. 2019YFA0705000 and 2017YFA0303700), the Key R&D Program of Guangdong Province (Grant No. 2018B030329001), the Leading-Edge Technology Program of Jiangsu Natural Science Foundation (Grant No. BK20192001), and the National Natural Science Foundation of China

We demonstrate a broadband optical parametric oscillation, using a sheet cavity, via cavity phase-matching. A 21.2 THz broad comb-like spectrum is achieved, with a uniform line spacing of 133.0 GHz, despite a relatively large dispersion of 275.4 fs2/mm around 1064 nm. With 22.6% high slope efficiency, and 14.9 kW peak power handling, this sheet optical parametric oscillator can be further developed for χ (2) comb.

Compressive Underwater Sonar Imaging with Synthetic Aperture Processing

Synthetic aperture sonar (SAS) is a technique that acquires an underwater image by synthesizing the signal received by the sonar as it moves. By forming a synthetic aperture, the sonar overcomes physical limitations and shows superior resolution when compared with use of a side-scan sonar, which is another technique for obtaining underwater images. Conventional SAS algorithms require a high concentration of sampling in the time and space domains according to Nyquist theory. Because conventional SAS algorithms go through matched filtering, side lobes are generated, resulting in deterioration of imaging performance. To overcome the shortcomings of conventional SAS algorithms, such as the low imaging performance and the requirement for high-level sampling, this paper proposes SAS algorithms applying compressive sensing (CS). SAS imaging algorithms applying CS were formulated for a single sensor and uniform line array and were verified through simulation and experimental data. The simulation showed better resolution than the ω-k algorithms, one of the representative conventional SAS algorithms, with minimal performance degradation by side lobes. The experimental data confirmed that the proposed method is superior and robust with respect to sensor loss.

Uniform and monotone line sum optimization

The line sum optimization problem asks for a (0,1)-matrix minimizing the sum of given functions evaluated at its row and column sums. We show that the uniform problem, with identical row functions and identical column functions, and the monotone problem, over matrices with nonincreasing row and column sums, are polynomial time solvable.

Guiding magnetic liquid metal for flexible circuit

Liquid metal (LM) has potential applications in flexible electronics due to its high electrical conductivity and high flexibility. However, common methods of printing LM circuits on soft substrates lack controllability, precision, and the ability to repair a damaged circuit. In this paper, we propose a method that uses a magnetic field to guide a magnetic LM (MLM) droplet to print and repair a flexible LM circuit on a femtosecond (fs) laser-patterned silicone surface. After mixing magnetic iron (Fe) particles into LM, the movement of the resultant MLM droplet could be controlled by a magnetic field. A patterned structure composed of the untreated flat domain and the LM-repellent rough microstructure produced by fs laser ablation was prepared on the silicone substrate. As an MLM droplet was guided onto the designed pattern, a soft LM circuit with smooth, uniform, and high-precision LM lines was obtained. Interestingly, the MLM droplet could also be guided to repair the circuit broken LM lines, and the repaired circuit maintained its original electrical properties. A flexible tensile sensor was prepared based on the printed LM circuit, which detected the bending degree of a finger.

Farmer Dissemination of Seeds (FDS) Deployment Method Applied to Simulated Leach Protocol

Recent communication technologies in the Wireless Sensor Networks WSN enable us to implement and construct various physical sensing nodes with electronic circuits for transmitting and receiving tasks. Low-Energy Adaptive Clustering Hierarchy LEACH is a well-known routing protocol used and implemented in researches and articles; also, there are various attempts from the researchers to modify it to achieve the best results. Since almost all of the articles considered deployment either predefined or randomly depleted for the whole reign of interest RoI. A sophisticated random node deployment method is proposed, named Farmer Disseminating the Seeds FDS, the farmer walks with almost uniform steps and parallel lines to cover the whole RoI. A formation of a uniform grid with deviated random local distances from grid crossings considered as a predefined number of normal nodes with one advance node that has double battery energy. FDS is used to improve the importance of deployment methods as an additive parameter in estimating lifetime and energy consumption in routing protocols. Traditional random deployment and FDS methods are compared.

Compact 5G Hairpin Bandpass Filter Using Non-Uniform Transmission Lines Theory

A compact three order 5G low frequency band Hairpin Bandpass Filter (HPBF) is analyzed, designed and fabricated in this paper. The designed filter operates at 5G frequency range (5.975-7.125 GHz). 17.76% compactness in each λ/2 uniform transmission line (UTL) resonator of the filter is achieved by applying Non-Uniform Transmission Lines (NTLs) theory. This compactness will make modern wireless transmitter and receiver designs more compatible. Study on the best reduction size percentage and suitable constraints to design the required NTL resonator is highlighted in this paper. Six samples with different size reductions percentage are fabricated and measured. The simulation is carried out in this study uses High Frequency Structure Simulator (HFSS) software and Computer Simulation Technology (CST) software. The simulated results for UTL HPBF and NTL HPBF with the six cases are verified with measurement. For the best size reduction percentage design, the measured results demonstrated that the 6.55 GHz NTL and UTL HPBF show good impedance matching within the unsilenced 5G frequency band.

Parametric Fault Diagnosis of Very High-Frequency Circuits Containing Distributed Parameter Transmission Lines

Parametric fault diagnosis of analog very high-frequency circuits consisting of a distributed parameter transmission line (DPTL) terminated at both ends by lumped one-ports is considered in this paper. The one-ports may include linear passive and active components. The DPTL is a uniform two-conductor line immersed in a homogenous medium, specified by the per-unit-length (p-u-l) parameters. The proposed method encompasses all aspects of parametric fault diagnosis: detection of the faulty area, location of the fault inside this area, and estimation of its value. It is assumed that only one fault can occur in the circuit. The diagnostic method is based on a measurement test arranged in the AC state. Different approaches are proposed depending on whether the faulty is DPTL or one of the one-ports. An iterative method is modified to solve various systems of nonlinear equations that arise in the course of the diagnostic process. The diagnostic method can be extended to a broader class of circuits containing several transmission lines. Three numerical examples reveal that the proposed diagnostic method is fast and gives quite accurate findings.

Massive OAM‐MIMO transmission scheme for 5G networks and beyond

The combination of orbital angular momentum (OAM) and massive multiple-input multiple-output (MIMO) brings the possibility of almost infinite transmission capability, which may be applied in the coming 5th generation networks and beyond. In this study, a uniform line array (ULA)-based massive OAM-MIMO scheme in a multipath scene is presented. The cumulative phase of OAM carriers and multiple reference coordinate systems relative to each transmitting antenna are used to describe the OAM-MIMO wireless channel model theoretically. The performance indices of interest including capacity, energy efficiency, and capacity gain are numerically investigated in detail. The results indicate that the presented ULA-based massive OAM-MIMO scheme performs better overall than a conventional MIMO scheme via enhancing the OAM multiplexing intensity, and multi-fold capacity gain can be obtained especially in the low signal-to-noise rate communications.