Steering Approach Research Articles

Point-to-multipoint beam-steering terahertz communications using a photonics-based leaky-wave transmit antenna

Abstract We report on the successful implementation of a photonic-based beam steering approach for point-to-multipoint terahertz (THz) communications. The frequency-agile radiation properties of a THz leaky-wave antenna connected to a photodiode are utilized in the remote transmitter for generating multiple individually steerable THz beams. The approach benefits from the ultra-wide frequency tunability of optical heterodyne systems for frequency-agile THz beam steering. Moreover, the approach allows to exploit high performance and mature optical modulation techniques for generating THz beams with a high data capacity. In the THz receiver, a carrier frequency insensitive envelope THz detector based upon a single Schottky-barrier diode is used. In detail, THz communications in the 300 GHz band (WR3.4) with a maximum steering angle up to 90° is reported. Experimentally, for single steerable THz beam operation, a record high data rate of 35 Gbit/s at a wireless distance of 30 cm is achieved using two-level pulse amplitude modulation. Also, longer wireless distances up to 110 cm with 5 Gbit/s are demonstrated. Furthermore, point-to-multipoint THz communications is reported using two individually steerable THz beams carrying 10 Gbit/s and 5 Gbit/s over 70 cm and 50 cm, respectively.

Apodized slanted teeth grating couplers for LiDAR applications

Solid state LiDAR systems traditionally rely on costly active components for efficient beam scanning. In this study, we propose a cost-effective, purely passive steering approach using apodized slanted grating couplers. Through apodization, we achieve a uniform upward emission profile and enhanced upward transmission. Theoretical calculations indicate successful steering of 91.5∘×42.8∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$91.5^\\circ \ imes 42.8^\\circ$$\\end{document}. Experimental results closely match theoretical predictions, validating the capabilities of our passive steering concept. Additionally, the grating couplers, with a length of 3 mm, enable a farfield FWHM of 0.026∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}, further enhancing sensing resolution.

High-precision and low-noise dielectric tensor tomography using a micro-electromechanical system mirror.

Dielectric tensor tomography is an imaging technique for mapping three-dimensional distributions of dielectric properties in transparent materials. This work introduces an enhanced illumination strategy employing a micro-electromechanical system mirror to achieve high precision and reduced noise in imaging. This illumination approach allows for precise manipulation of light, significantly improving the accuracy of angle control and minimizing diffraction noise compared to traditional beam steering approaches. Our experiments have successfully reconstructed the dielectric properties of liquid crystal droplets, which are known for their anisotropic structures, while demonstrating a notable reduction in the background noise of the images. Additionally, the technique has been applied to more complex samples, revealing its capability to achieve a high signal-to-noise ratio. This development represents a significant step forward in the field of birefringence imaging, offering a powerful tool for detailed study of materials with anisotropic properties.

A Survey of Needle Steering Approaches in Minimally Invasive Surgery.

In virtue of a curved insertion path inside tissues, needle steering techniques have revealed the potential with the assistance of medical robots and images. The superiority of this technique has been preliminarily verified with several maneuvers: target realignment, obstacle circumvention, and multi-target access. However, the momentum of needle steering approaches in the past decade leads to an open question-"How to choose an applicable needle steering approach for a specific clinical application?" This survey discusses this question in terms of design choices and clinical considerations, respectively. In view of design choices, this survey proposes a hierarchical taxonomy of current needle steering approaches. Needle steering approaches of different manipulations and designs are classified to systematically review the design choices and their influences on clinical treatments. In view of clinical consideration, this survey discusses the steerability and acceptability of the current needle steering approaches. On this basis, the pros and cons of the current needle steering approaches are weighed and their suitable applications are summarized. At last, this survey concluded with an outlook of the needle steering techniques, including the potential clinical applications and future developments in mechanical design.

Mechanical azimuthal beam‐steering Fabry–Perot resonator antenna with large deflection angle

AbstractContinuous beam steering approach with minimal power consumption is highly desirable in modern antenna designs. A simple mechanical method for achieving beam steering in the Fabry–Perot resonator antenna (FPRA) is presented. It involves rotating the upper phase gradient metasurface (PGM) mechanically to change the aperture phase distribution, so the beam is continuously steered in the azimuthal plane while maintaining a large elevation angle. The proposed PGM unit cell comprises a hexagonal ring and patch printed on both sides of the substrate, along with a honeycomb lattice. A prototype antenna operating at 5.65 GHz is fabricated and measured to validate the feasibility. Measurement results show that the FPRA achieves a gain of 14.9 dBi, and can continuously steer its beam in the azimuthal plane with an elevation angle of around θ = 50°. Measured radiation patterns in eight azimuthal directions (φ = 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°) are consistent with the simulated results. Compared with other electrical tuning methods, our design has a compact size and requires lower power for the PGM rotation.

An integrated steering approach to improve a phosphate supply chain efficiency

ABSTRACT This paper presents and illustrates an original application of the redesign in the real context of a mining supply chain producing phosphate rock. One of the major challenges is to successfully produce the final products required by the customers, from raw materials whose chemical composition and availability depend on the extraction program and method. Redesign of the mining supply chain consists of considering the impact of extraction, processing, and blending stages in achieving target objectives. The proposed approach, based on a mixed integer linear programming model, allows moving from fixed production flows to dynamic ones by adopting a flexible and reactive management mode that fully satisfies customer requirements at minimum production costs. Numerical results obtained using real data, corresponding to the infrastructure and order books, illustrate (i) the flexibility, quality, and horizontal alignment ensured by our approach and (ii) the impact of the extraction method on the ability of the SC to fulfil the orders book with more efficiency.

Analisis Kebijakan Dana Desa Dalam Konsep Blue Economy Untuk Peningkatan Kesejahteraan Masyarakat Desa Di Sumatera Utara

The Indonesia Sustainable Oceans program is to support Indonesia's change to a blue economy by advancing the financial, social and natural advantages got from sound beach front and sea biological systems. This study expects to complete an enlightening monetary examination of the improvement of the Town Cash strategy connected with the issue of executing the Blue Economy idea in North Sumatra Territory, Doing recognizable proof and assessment of the utilization of the Blue Economy idea in Langkat Rule and Focal Tapanuli Regime, North Sumatra Territory, Assessing the impact of the Social Strength Record, Financial Versatility File and Ecological Flexibility List fair and square of government assistance of town networks in the waterfront areas of Langkat Rule and Focal Tapanuli Rule, North Sumatra Territory. This study utilizes quantitative and subjective strategies to answer the current issue detailing. The consequences of this study are that the Coronavirus pandemic an affects steering approaches for utilizing Town Cash. Where, in 2023, the need utilization of Town Cash is focused on public monetary recuperation, public need projects, and alleviation for dealing with regular and non-cataclysmic events in supporting the accomplishment of the Town SDGs. At present there is no exceptional program that utilizes town cash to foster beach front regions or an extraordinary Blue Economy program in Focal Tapanuli locale and Langkat region. To some degree, the Social Flexibility File (IKS) variable impacts the Local area Government assistance variable, the Financial Versatility Record (IKE) variable affects the Local area Government assistance variable, the Natural Strength File (IKL) variable affects the variable Public government assistance. And that truly intends that in the event that the IKS, IKE, IKL factors progress, the degree of government assistance of the town local area additionally propels.

A compressed sensing-based approach for null steering in partially adaptive planar arrays using a reduced number of adjustable array elements

This paper proposes two methods for multi-wide null steering in the beampattern of preconfigured partially adaptive planar array antennas using convex optimization and sparse recovery theory. The array elements are split into two categories. One of which is nonadjustable or has fixed excitations, and the other is adjustable. The weights of the adjustable part are perturbed to form wide nulls at the interference directions. In the first proposed method, all the adaptive array elements are used to steer the nulls. Here, convex optimization is used to obtain the required weight perturbations of all the adaptive elements. In addition to the constraints that are needed to impose the nulls, constraints were added to mitigate the pointing error and the lower peak-to-sidelobe ratio (PSLR) problems. In the second proposed method, the optimization problem is cast as a sparse recovery problem to reduce the number of elements to be perturbed from the set of adjustable elements only. The optimization problem is then relaxed to achieve a convex optimization problem and solved iteratively to cut down the number of radiating elements which needs to be perturbed from the set of adjustable elements. Simulations were conducted for different sizes of planar arrays up to a few hundred antennas and different configurations of adjustable elements. The results showed that changing the excitations of only 20-35% of the adjustable array elements is sufficient to steer the nulls without any pointing error or decrease in the PSLR. Also, the interference rejection ratio (IRR) achieved by the proposed methods is better than the minimum mean square error (MMSE) analytical solution.

Depth-based Sampling and Steering Constraints for Memoryless Local Planners

By utilizing only depth information, the paper introduces a novel two-stage planning approach that enhances computational efficiency and planning performances for memoryless local planners. First, a depth-based sampling technique is proposed to identify and eliminate a specific type of in-collision trajectories among sampled candidates. Specifically, all trajectories that have obscured endpoints are found through querying the depth values and will then be excluded from the sampled set, which can significantly reduce the computational workload required in collision checking. Subsequently, we apply a tailored local planning algorithm that employs a direction cost function and a depth-based steering mechanism to prevent the robot from being trapped in local minima. Our planning algorithm is theoretically proven to be complete in convex obstacle scenarios. To validate the effectiveness of our DEpth-based both Sampling and Steering (DESS) approaches, we conducted experiments in simulated environments where a quadrotor flew through cluttered regions with multiple various-sized obstacles. The experimental results show that DESS significantly reduces computation time in local planning compared to the uniform sampling method, resulting in the planned trajectory with a lower minimized cost. More importantly, our success rates for navigation to different destinations in testing scenarios are improved considerably compared to the fixed-yawing approach.

Design of an alternate antibody fragment format that can be produced in the cytoplasm of Escherichia coli

With increased accessibility and tissue penetration, smaller antibody formats such as antibody fragments (Fab) and single chain variable fragments (scFv) show potential as effective and low-cost choices to full-length antibodies. These formats derived from the modular architecture of antibodies could prove to be game changers for certain therapeutic and diagnostic applications. Microbial hosts have shown tremendous promise as production hosts for antibody fragment formats. However, low target protein yields coupled with the complexity of protein folding result in production limitations. Here, we report an alternative antibody fragment format ‘FabH3’ designed to overcome some key bottlenecks associated with the folding and production of Fabs. The FabH3 molecule is based on the Fab format with the constant domains replaced by engineered immunoglobulin G1 (IgG1) CH3 domains capable of heterodimerization based on the electrostatic steering approach. We show that this alternative antibody fragment format can be efficiently produced in the cytoplasm of E. coli using the catalyzed disulfide-bond formation system (CyDisCo) in a natively folded state with higher soluble yields than its Fab counterpart and a comparable binding affinity against the target antigen.

A multi-objective decentralized optimization for voltage regulators and energy storage devices in active distribution systems

Centralized optimization methods have been widely used to manage the operation of distribution systems. However, these methods have some restrictions, such as the high computational cost, the reliance on a centralized computer system, and the lack of data privacy. To overcome these limitations, decentralized optimization methods have been proposed in recent years. Decentralized methods divide the control variables of the centralized optimization problem over several controllers, and each controller solves its own subproblem independently. This paper presents a multi-objective optimization framework for managing the operation of distribution systems. The primary objective of the proposed method is to optimize the tap positions of voltage regulators and charging and discharging powers for energy storage devices locally through a decentralized coordination process. The used objective functions take into account the voltage profile within the network, the lifetime of the devices, and the energy losses in the systems. Two decentralized methods, based on the Advanced Arithmetic Optimizer algorithm and the Profile Steering approach, are proposed to address the limitations of centralized optimization methods. The decentralized methods aim to improve the reliability and efficiency of the optimization process, while also minimizing communication and computational costs. The proposed methods are evaluated and compared to a centralized approach using the IEEE 33 and 69 bus systems. The results demonstrate that the proposed decentralized methods can effectively resolve voltage problems, minimize energy losses, and find high-quality solutions with improved computational efficiency compared to the centralized approach.

A Reconfigurable Microstrip Patch Antenna With Switchable Liquid-Metal Ground Plane

This paper presentsa novel reconfigurable microstrip patch antenna that is reconfigured using liquid metal. The proposed antenna employs two approaches in unison to switch the direction of the main beam. Specifically, the antenna uses the parasitic steering approach together with a novel switchable ground plane. The antenna operates at 5.9 GHz. It consists of a driven patch surrounded by four parasitics. All five elements are circular disk resonators. Each of the parasitic resonators incorporate a drill hole. The drill holes can be filled or emptied of liquid metal to control the behavior of the parasitics. The ground plane incorporates two reconfigurable segments. The switchable ground plane can be reshaped by adding or removing the additional segments of ground plane which are formed from liquid metal. To the best of the authors' knowledge, this is the first antenna that is capable of reconfiguring its radiation pattern by reshaping the ground plane using liquid metal. A hardware prototype of the antenna was fabricated and measured. The measurement results show that the antenna can switch between five different beam directions, namely: 0°, ±20°, and ±40°. The design has only 0.5 dB of scan loss across the beam switching range.

Hybrid Mechanical and Electronic Beam Steering for Maximizing OAM Channel Capacity

Radio frequency-orbital angular momentum (RF-OAM) is a novel approach of multiplexing a set of orthogonal modes on the same frequency channel to achieve high spectrum efficiencies. Since OAM requires precise alignment of the transmit and the receive antennas, the electronic beam steering approach has been proposed for the uniform circular array (UCA)-based OAM communication system to circumvent large performance degradation induced by small antenna misalignment in practical environment. However, in the case of large-angle misalignment, the OAM channel capacity cannot be effectively compensated only by the electronic beam steering. To solve this problem, we propose a hybrid mechanical and electronic beam steering scheme, in which mechanical rotating devices controlled by pulse width modulation (PWM) signals as the execution unit are utilized to eliminate the large misalignment angle, while electronic beam steering is in charge of the remaining small misalignment angle caused by perturbations. Furthermore, due to the interferometry, the receive signal-to-noise ratios (SNRs) are not uniform at the elements of the receive UCA. Therefore, a rotatable UCA structure is proposed for the OAM receiver to maximize the channel capacity, in which the simulated annealing algorithm is adopted to obtain the optimal rotation angle at first, then the servo system performs mechanical rotation, at last the electronic beam steering is adjusted accordingly. Both mathematical analysis and simulation results validate that the proposed hybrid mechanical and electronic beam steering scheme can effectively eliminate the effect of diverse misalignment errors of any practical OAM channel and maximize the OAM channel capacity.

Dispersion-free steering beam based alignment at SwissFEL

Micron-level alignment of the undulator line is required for successful operation of linear accelerator based high gain free electron lasers to produce powerful radiation at X-rays’ wavelengths. Such precision in the straightness of the trajectory allows for an optimal transverse superposition between the electrons and the photon beam. This is extremely challenging and can only be achieved via beam-based techniques. In this paper we will report on the dispersion-free steering approach implemented at SwissFEL, that helped achieving improved performance for both the hard and soft X-ray beamlines.

Design and Analysis of a Multiple and Wide Nulling Collaborative Beamforming Scheme in the Domain of 3-Dimensional Wireless Sensor Networks

Null steering is essential in collaborative beamforming (CB) in wireless sensor networks (WSNs) to ensure minimal radiation power and interference in the direction of unintended receivers. Current research in null steering in CB in WSNs is mainly from the perspective of planar arrangements of sensor nodes and sink(s). Furthermore, there is no research dedicated to the formation of multiple wide nulls during CB in 3-dimension WSNs. Wide nulls are ideal in scenarios featuring mobile unintended sink(s). A new multiple and wide null steering scheme applicable to CB in WSNs is presented in this work (from the perspective of a 3-dimensional random arrangement of static sensor nodes). It is assumed that desired nulling directions are implicitly known at a CB cluster head. A particle swarm optimization (PSO) algorithm variant is applied in concurrent node transmit amplitude and phase perturbation with an aim of achieving beam steering alongside multiple and wide null steering. The performance of the proposed null steering scheme is validated against a basic null steering approach (with reference to current literature). Furthermore, a comparative null depth, width, and nulling accuracy analysis are done upon varying the count of collaborating nodes and the collaborating cluster radius. An increase in the number of collaborating nodes is found to increase nulling depth at an exponentially decaying rate. An increase in the collaborating nodes’ cluster radius yields a reduction in null width. The contributions of this work to the existing literature are as follows: (i) the design and investigation of a null steering scheme from the perspective of a 3-dimension random arrangement of sensor nodes; (ii) the design of a concurrent beam steering and multiple wide null steering scheme on the basis of concurrent node transmit amplitude and phase perturbation whilst ensuring null depth uniformity; (iii) a statistical analysis of the impact of a count of collaborating nodes and collaborating cluster radius on nulling performance; (iv) investigation of capacity improvement at unintended receivers upon null steering.

The CathPilot: A Novel Approach for Accurate Interventional Device Steering and Tracking

Accurate device navigation and control are significant challenges in various minimally invasive cardiovascular interventions. The long length of the devices used (e.g., catheters and guidewires), their high flexibility, and their engagement with the tortuous anatomy limit the accurate and reliable control and navigation of the device's tip. This article aims to design, develop, and assess a novel alternative solution that promises to overcome the major limitations of conventional devices. By utilizing an expandable cable-driven mechanism and a corresponding 3-D cam surface for cable length adjustment, we propose a fully manually operated system that can be navigated through the tortuous anatomy and then teleoperated to allow for accurate, reliable, and localized position control and tracking of the device. In this article, the methods of design, development, and verifications of this system are presented. The system's performance is assessed under different path tortuosity conditions and different opening diameters of the expandable frame. Our results indicate that the proposed system provides complete teleoperation of the device within the full reachable workspace of the mechanism and allows for positioning and tracking of the device with submillimeter accuracy irrespective of the tortuosity of the path and expansion size of the frame. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ex-vivo</i> phantom model experiments also show the device significantly outperforms conventional devices in terms of navigation time and success rate. The CathPilot allows for direct manipulation, accurate positioning, and tracking of the device tip relative to the anatomy, promising to overcome some of the major limitations of conventional interventional devices.

Coordination Control Strategy for Human-Machine Cooperative Steering of Intelligent Vehicles: A Reinforcement Learning Approach

This paper proposes a novel coordination control strategy through reinforcement learning approach for human-machine cooperative steering of intelligent vehicles, so as to realize a more flexible and efficient way for the human driver and the automated driving system to jointly complete the path-following. Firstly, the human-machine cooperative steering is modeled by the optimal preview driver model with adaptive preview time and the MPC lateral tracking model with adaptive prediction horizon and step, as well as the steering system with a realistic dual-motor steering-by-wire structure is also built into the human-machine cooperative steering system. Then, the human-machine coordination control strategy is designed and trained based on two reinforcement learning agents to further optimize the allocation of cooperative steering weights. Finally, the strategy is fully verified in lane departure simulation scenarios and also in real-world Steering-in-the-Loop experiments with real-time controller, which shows that both agents can effectively keep the vehicle with the small lateral and yaw errors in the simulation scenarios, and also can be successfully applied in the realistic human-machine cooperative system to maintain the lateral and yaw errors within a safe range during path-following.

A 1.2 V high‐speed low‐power preamplifier latch‐based comparator

The power consumption of chips has emerged as a major concern with the increased integration of analog circuitry. This work focuses on a two-stage comparator based on a preamplifier with latch for a successive approximation analog-to-digital converter. In order to minimize power loss and delay time, the charge steering approach was used in the design of latch as well as preamplifier. The suggested comparator is simulated in SMIC 0.18-um process in comparison to the comparator without charge steering mode. The results reveal that the average power consumption is only around 22 uW for varied input voltage at a supply voltage of 1.2 V, which is relatively lowered by approximately 30%. Meanwhile, delay time is also reduced by about 25%.

Steering-by-example for Progressive Visual Analytics

Progressive visual analytics allows users to interact with early, partial results of long-running computations on large datasets. In this context, computational steering is often brought up as a means to prioritize the progressive computation. This is meant to focus computational resources on data subspaces of interest so as to ensure their computation is completed before all others. Yet, current approaches to select a region of the view space and then to prioritize its corresponding data subspace either require a one-to-one mapping between view and data space, or they need to establish and maintain computationally costly index structures to trace complex mappings between view and data space. We present steering-by-example, a novel interactive steering approach for progressive visual analytics, which allows prioritizing data subspaces for the progression by generating a relaxed query from a set of selected data items. Our approach works independently of the particular visualization technique and without additional index structures. First benchmark results show that steering-by-example considerably improves Precision and Recall for prioritizing unprocessed data for a selected view region, clearly outperforming random uniform sampling.

A Hybrid True-Time and Phase-Delayed Approach for Millimeter-Wave Beam Steering

In this research study, a novel hybrid approach to beam steering based on the combination of true time delay and phase shift to enable continuous beam steering with minimal beam squint in wideband mm-wave transceivers is investigated. With modern high-speed communication links in the mm-wave spectrum requiring ever higher bandwidths, and losses increasing with frequency, there is a need for steerable arrays in mobile applications. This steering capability is commonly realized by phase shifters, which enable continuous beam direction control, but produce significant beam squint at large bandwidths or steering directions. An alternative is to use a time-delayed control, which resolves the squint issue but covers only a limited number of beam directions, producing considerable loss and being large in size. This research work presents the first 2-bit time delay stage operating above 200 GHz. In addition, a novel approach is described to enable broadband continuous beam control with minimal beam squint; this is achieved by combining the time delay circuit with a 90° vector-sum phase shifter. To prove the concept, the circuit is realized in a 130-nm SiGe Bipolar Complementary Metal Oxide Semiconductor (CMOS) (BiCMOS) technology. At 4.33 mW of dc power consumption, the small-signal gain is −8.6 dB at a 3-dB band of 220–250 GHz, resulting in 12.8% of relative bandwidth. The time delay stage provides coarse beam direction control with a maximum steering angle of 43.9° resulting from a maximum delay of 1.47 ps with a resolution of 0.39 ps. Across all tuning states, the root-mean-square delay error is less than 23.7 fs. The following phase shifter enables fine direction control while also compensating ±1.5 dB of gain variation resulting from the time delay. This is achieved while reducing the area consumption to half of what is required for comparable true time delay circuits. In a minimal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> antenna array, this enables continuous beam direction control between ±54.6° while limiting the beam squint to less than 2.5°, equating to a more than 75% reduction in comparison to the common phase shift approach.