Steerable Pattern Research Articles

Pattern reconfigurable antenna with two-dimensional beam steering capability using metasurface

A two-dimensional (2-D) beam steering pattern reconfigurable antenna with an active partially reflecting surface (PRS) is presented in this paper. The proposed design incorporates a U-slot patch antenna functioning as a radiator and a superstrate composed of an active PRS layer. The PRS superstrate layer consists of 6 × 6 unit cells, divided into four sections, each comprised of 3 × 3 unit cells. To achieve reconfigurability, each unit cell within the PRS layer is loaded with two PIN diodes. Phase inconsistency can be introduced by changing the states of the PIN diode at different sections, which causes the PRS antenna to change the direction of its main beam. By controlling the operating states of PIN diodes within each unit cell, a total of sixteen radiation patterns can be generated. The proposed antenna supports 2-D beam steering in both the xz- and yz-planes, allowing for a maximum steered angle of ±40°. The performance of the fabricated antenna is experimentally verified at an operating frequency of 3.5 GHz. The proposed antenna is suitable for the 5G NR frequency band n78 and operates within the frequency range of 3.3 to 3.8 GHz.

The impact of changes in steering patterns on the probability of hurricanes making landfall in the New York City area

AbstractWe investigated the variability of annual frequencies of upper air steering patterns that were similar to the one that resulted in the recurvature of Hurricane Sandy's track towards the US east coast in 2012. The analyses showed that such steering patterns could occur over 50 times yearly, with higher probabilities in the colder season. The frequencies of these events have decreased since the beginning of the observations in 1979; however, this trend has reversed in the past 10–15 years. These trends are aligned with trends in the intensity of the negative phase North Atlantic Oscillation and the positive phase of the Southern Oscillation Index. In addition to the long‐term trends, we observed a significant periodicity in the annual frequencies of the steering pattern around 6–8 years. Combining the probabilities of relevant steering patterns with the probabilities of hurricanes per season in the relevant domain led to the conclusion that the overall probability of events like Sandy increased from approximately 0.26% in 1979 (0.48 days) to 0.45% (0.81 days) per season since 1979.

In-plane magnetic field-driven symmetry breaking in topological insulator-based three-terminal junctions

Topological surface states of three-dimensional topological insulator nanoribbons and their distinct magnetoconductance properties are promising for topoelectronic applications and topological quantum computation. A crucial building block for nanoribbon-based circuits are three-terminal junctions. While the transport of topological surface states on a planar boundary is not directly affected by an in-plane magnetic field, the orbital effect cannot be neglected when the surface states are confined to the boundary of a nanoribbon geometry. Here, we report on the magnetotransport properties of such three-terminal junctions. We observe a dependence of the current on the in-plane magnetic field, with a distinct steering pattern of the surface state current towards a preferred output terminal for different magnetic field orientations. We demonstrate that this steering effect originates from the orbital effect, trapping the phase-coherent surface states in the different legs of the junction on opposite sides of the nanoribbon and breaking the left-right symmetry of the transmission across the junction. The reported magnetotransport properties demonstrate that an in-plane magnetic field is not only relevant but also very useful for the characterization and manipulation of transport in three-dimensional topological insulator nanoribbon-based junctions and circuits, acting as a topoelectric current switch.

Microstrip leaky wave antenna for wide range of beam scanning in X band

AbstractIn this work, design of a pattern reconfigurable antenna is presented for X‐band applications as a leaky wave antenna (LWA) realization. Due to the advantages of simple design schematic, low profile, and easy impedance matching, LWA designs have been using as an efficient solution for reconfigurable antenna in many wireless communication applications. Optimization and simulation of the proposed LWA is carried out in 3‐D Microwave simulation CST environment and Honey Bee Mating is used as the optimization algorithm. Dimensions of the proposed LWA is 130 × 30 mm, which is fabricated on Rogers 5880 as capacitive loaded eight identical rectangular microstrip patches operating over 9.5‐12 GHz with a fractional bandwidth. The proposed LWA exhibits a measured peak gain of 11.8 dBi at 10 GHz with an overall gain characteristic of between 9.5 and 11.8 dBi over the range of 9.5 to 12 GHz with a steerable pattern characteristics between −45 and 50° as agreed with the theory. Furthermore, the fabricated LWA has been found to have the superior performance as compared with its counterparts.

An Inverse Microphone Array Method for the Estimation of a Rotating Source Directivity

Microphone arrays methods are useful for determining the location and magnitude of rotating acoustic sources. This work presents an approach to calculating a discrete directivity pattern of a rotating sound source using inverse microphone array methods. The proposed method is divided into three consecutive steps. Firstly, a virtual rotating array method that compensates for motion of the source is employed in order to calculate the cross-spectral matrix. Secondly, the source locations are determined by a covariance matrix fitting approach. Finally, the sound source directivity is calculated using the inverse method SODIX on a reduced focus grid. Experimental validation and synthetic data from a simulation are used for the verification of the method. For this purpose, a rotating parametric loudspeaker array with a controllable steering pattern is designed. Five different directivity patterns of the rotating source are compared. The proposed method compensates for source motion and is able to reconstruct the location as well the directivity pattern of the rotating beam source.

Multibeam steered pattern synthesis in time‐modulated antenna array with controlled harmonic radiation

This article deals with the synthesis of multibeam steerable patterns in time-modulated arrays (TMAs) for electronic scanning. The simultaneous generation of multiple beams in TMAs can be achieved through the exploitation of undesired harmonic radiations emitted at the multiples of modulating frequency due to the periodic switching. The direction-dependent harmonic beams are capable of producing independent information channels with different spatial distributions beneficial for electronic beam steering. Multibeam patterns associated with harmonic frequencies along with the fundamental pattern can be synthesized with suitably designed switching schemes. The potentialities of linear TMAs are explored in this article to generate a simultaneous sum and difference pattern useful for monopulse tracking systems. Further assessment of multipattern operations with linear TMAs are proposed with beam steering at lower-order harmonics. Steered double sum pattern with controlled harmonic radiations are also generated to achieve a steered multibeam with simplified beamforming network. Towards this aim, both the analytical and the optimized solutions of periodic switching sequences for different multibeam patterns are developed. Modified differential evolution with a wavelet-based mutation strategy (DEWM) is employed for the optimal solution. Representative results are assessed and compared with other published literature results to show the effectiveness of the proposed methods.

A fractional phase-coding strategy for terahertz beam patterning on digital metasurfaces.

Coding metasurfaces have drawn great attention for its digital wave manipulation in deep subwavelength-scale in the last decade, more sophisticated and flexible coding strategies suitable for terahertz wavefront manipulations are becoming more urgently demanded. Due to its rigidity in phase gradient division, both phase gradient metasurfaces and conventional phase coding technique lack the flexibility to expand applications in a large field of view and accurate targeting. This study presents a generalized coding method by precisely reconfiguring the array factor based on the phased array theory and metasurface concept, which can be applied for anomalous scattering and ultrafine radiation patterning. According to our quantitative analysis on the relationship between the deflected angles and the supercell spacing, a fractional coding method for arbitrary phase gradient distribution has been attained by logically discretizing the spacing scale of supercells. By switching on different coding sequences or incident frequencies, a single beam to multiple beam scanning in an expanded angular range with minimal step can be achieved on the fractional phase-coding metasurfaces. As a proof of concept, the 2-bit coding metasurfaces arranged by four fractional coding sequences have been fabricated and measured, demonstrating a consecutive single-beam steering pattern ranging from 22° to 74° in 0.34-0.5 THz. Crosswise verified by the good accordance among numerical prediction, simulation and experiment, the proposed coding strategy paves a path to delicate beam regulation for high-resolution imaging and detection.

Improved Vehicle Steering Pattern Recognition by Using Selected Sensor Data

Smartphone built-in sensors are essential components of vehicle steering mode recognition. Related driver assistance systems (DAS) and abnormal driving behavior detection systems have been studied for many years. However, the existing solutions and systems simply collect sensor data with a fixed sliding window and fuse data from multiple sensors using simple thresholds to detect different driving behaviors. The weakness of these solutions can have an adverse impact on the energy consumption and computation complexity of power-limited devices such as smartphones, and may provide coarse-grained results. In this paper, we present a new method to reduce both the energy consumption and the computation complexity, and improve the recognition accuracy of vehicle steering patterns using the following three improvements: 1) a MultiWave filter is designed to replace the fixed sliding window, which is used to identify vehicle steering events; 2) a set of eight statistical sensor features reflecting the vehicle steering modes are identified by extracting statistical features from different sensors and different axes; 3) different machine learning methods are compared based on this feature set in order to improve classifier training (Decision Tree and Random Forest). Evaluation results based on real vehicle datasets show that our improved classifiers have high real-time recognition accuracy of the five most common steering modes: left/right turns, left/right lane changes and U-turns. We also took a simple on-road testing, in which both of the two models detected all the steering behaviors under low vehicle speed.

An Extended Least Squares Method for Aliasing-Resistant Vector Velocity Estimation.

An extended least squares method for robust, angle-independent 2-D vector velocity estimation using plane-wave ultrasound imaging is presented. The method utilizes a combination of least squares regression of Doppler autocorrelation estimates and block matching to obtain aliasing-resistant vector velocity estimates. It is shown that the aliasing resistance of the technique may be predicted using a single parameter, which is dependent on the selected transmit and receive steering angles. This parameter can therefore be used to design the aliasing-resistant transmit-receive setups. Furthermore, it is demonstrated that careful design of the transmit-receive steering pattern is more effective than increasing the number of Doppler measurements to obtain robust vector velocity estimates, especially in the presence of higher order aliasing. The accuracy and robustness of the method are investigated using the realistic simulations of blood flow in the carotid artery bifurcation, with velocities up to five times the Nyquist limit. Normalized root-mean-square (rms) errors are used to assess the performance of the technique. At -5 dB channel data blood SNR, rms errors in the vertical and horizontal velocity components were approximately 5% and 15% of the maximum absolute velocity, respectively. Finally, the in vivo feasibility of the technique is shown by imaging the carotid arteries of healthy volunteers.

An analysis of the operational GFS simplified Arakawa Schubert parameterization within a WRF framework: A Hurricane Sandy (2012) long‐term track forecast perspective

AbstractHurricane Sandy (2012) is known as an incredibly destructive storm and one defined meteorologically by its large size, and its significant forecast track spreads among various operational models roughly 1 week before landfall. While the operational European Centre for Medium‐Range Weather Forecasts model accurately depicted a northeastern United States landfall, the Global Forecasting System (GFS) model consistently forecast a track toward the North Atlantic Ocean. Using a Weather Research and Forecasting (WRF) model framework, Bassill () suggested that these differences were primarily a function of differences between the two models' cumulus parameterization (CP). This study also uses a WRF model framework to examine the simplified Arakawa Schubert CP used in the GFS model. It is found that increasing the deep convective entrainment coefficient produces more realistic forecast tracks for forecasts initialized roughly 1 week before landfall. This occurs through a reorientation of the precipitation (and associated latent heating) around Sandy during a critical time period in which it was interacting with a series of upper troughs to its west and northwest. Reorienting the latent heating reshapes the upper tropospheric steering pattern toward the one that is more negatively tilted and consistent with observations.

Non-Foster Loaded Parasitic Array for Broadband Steerable Patterns

Parasitic arrays can generate steerable patterns using tunable reactive loads at the parasitic elements to provide the required phase for the scattered radiation. However, the radiation that is coupled to the parasitic elements and reflected by the attached loads has a frequency dependent phase delay, leading to a beam/null squint effect and a limited instantaneous squint-free bandwidth. In this paper, we introduce a technique for eliminating this frequency dependence using non-Foster parasitic loads, whose reflection phase has a positive phase dispersion slope that can cancel the negative phase dispersion slope associated with propagation delays. Further, by tuning the non-Foster load, we can tune the total scattered phase to achieve steerable patterns. Tunable non-Foster impedances can be designed using transistor-based negative impedance convertor (NIC) circuits. A two element parasitic array was designed for the frequencies of operation of discrete device NICs. Non-Foster impedances required for obtaining broadband or squint-free nulls at different azimuth angles were calculated using array theory and simulations. An NIC that generated the non-Foster impedance for a broadside broadband null was fabricated and attached to the parasitic antenna. Simulation and measurement results showed broadband uniform nulls from 180-350 MHz, providing about twice the null bandwidth of a passive parasitic load. Null steering across some angles of the azimuth was restricted by the stability constraints of the NIC while being tuned. With a judicious design of the parasitic antenna and the NIC, we can achieve broader bandwidths and steerable patterns with non-Foster parasitic arrays.

Array pattern synthesis approach using a genetic algorithm

In this study, a new array pattern synthesis approach using a genetic algorithm (GA) is proposed. The proposed approach has a unique set of objectives to be achieved by exploiting the GA optimisation capabilities. These objectives are: (i) steering the pattern main lobe in the direction of the signal of interest, (ii) minimising the side lobes level, (iii) steering pattern nulls in the directions of jammers and interferers, (iv) forcing the pattern nulls to have prespecified values in order to insure sufficient elimination of jammers and interferers and (v) the whole pattern synthesis will be done by changing the amplitudes and phases of the array elements’ complex weights without any physical changes in the array; thus the method will be suitable for adaptive processing applications in which the array pattern will be dynamically adapted to the environments. Numerical examples will be used to demonstrate the effectiveness of the proposed array pattern synthesis approach using a uniform linear array of isotropic elements. Finally, the effect of changing the array number of elements and the weighting factor will be investigated using numerical examples.

Environmental Impact Assessment and Integrated Water Resources Management

Environmental Impact Assessment (EIA) plays an important role in the framework of the efforts aiming at the formulation of a complete water resources management. In our paper this issue is examined in an integrated way. The following issues are particularly examined : the notion of the EIA in general, the assessment methods and techniques on the basis of the suitability of their use, the economic aspects, the Greek legislative framework, case-law positions in general as well as the action and the steering pattern of the Greek Public Administration concerning this issue. This paper presents some conclusions and proposals which are drawn by the aforementioned integrated approach.

3306 前後輪アクティブステアを有する電気自動車における航続距離延長のための最適姿勢の設計法の提案(OS3-2 設計と制御,OS3 交通・物流システムの制御,オーガナイズド・セッション(OS))

In this paper, a method of designing front and rear steering pattern is proposed. Front and Rear active steering enable vehicle to be controlled by lateral force and side slip angle independently. Thus, researches have been done to decrease cornering resistance for each seconds. However, those methods can not completely realise the minimum energ consumption y in total. Therefore, a method of designing the optimal heading angle pattern under trajectory patterns and a control to realise the optimal heading pattern sre proposed. The effectiveness of proposed method is verified by simulations and experiments.

Driving simulation protocol to determine steering strategies

ObjectiveThis paper aims to propose an experimental protocol that allow to measure the steering behavior of drivers under equal tracks. BackgroundIn order to improve the existing electric power steering system, there is a need for a better understanding of the steering task, especially for building functional driver profiles for the disabled population. MethodWe built the experimental platform proposed in this paper in order to measure the steering actions with control and disabled groups. This platform reproduces the driving position and simulates driving conditions. In addition, the platform offers a fully instrumented steering wheel and is compatible with motion capture systems and complies with the hospital's recommendations. We added a specific driving simulation protocol based on a line-tracking task. The line's shape causes the subject to reproduce steering angle that was recorded with a real car. This way, the protocol insures that the subjects perform steering patterns that are similar enough to be compared at low driving speeds. The protocol was tested on control and disabled groups. ResultsResults showed that the task was correctly performed and that all subjects completed the task with a low enough deviation, thus insuring good repeatability. We compared the steering pattern of all the subjects, and we suggest some inter-group differences, especially in steering velocity. ConclusionThe experimental platform induces the subjects to complete driving itineraries with comparable steering patterns. Other parameters can now be compared to fulfill a more in-depth analysis of the steering action in the disabled population, in order to define functional profiles of drivers. Relevance to industryExisting electric power steering system will be adapted to functional profiles of drivers that will be defined from the proposed experimental protocol.

Solving Some Array Synthesis Problems by Means of an Effective Hybrid Approach

Most global optimization based synthesis procedures act in essentially the same way on all the involved variables. In this paper, it is theoretically discussed and numerically emphasized how explicit exploitation of the convexity of the problem with respect to a part of the degrees of freedom (when available) allows to achieve increased performances with respect to previous results, and to develop new interesting design solutions. Examples are presented for the synthesis of both sum and difference patterns by using nonuniformly spaced arrays and for the so called "optimal compromise amongst sum and difference patterns." Finally, the proposed approach is exploited in developing effective design solutions (based on the concept of interleaved arrays) to the problem of achieving very flexible antennas while using simple feeding networks. As an example, array antennas capable to radiate two different beams with individually steerable patterns, or to perform jammer rejection at the physical layer or even to realize a "flat-top" beam pattern are synthesized and presented

The time course of a lane change: Driver control and eye-movement behavior

In this paper we explore the time course of a lane change in terms of the driver’s control and eyemovement behavior. We conducted an experiment in which drivers navigated a simulated multi-lane highway environment in a fixed-base, medium-fidelity driving simulator. We then segmented the driver data into standardized units of time to facilitate an analysis of behavior before, during, and after a lane change. Results of this analysis showed that (1) drivers produced the expected sine-wave steering pattern except for a longer and flatter second peak as they straightened the vehicle; (2) drivers decelerated slightly before a pass lane change, accelerated soon after the lane change, and maintained the higher speed up until the onset of the return lane change; (3) drivers had their turn signals on only 50% of the time at lane-change onset, reaching a 90% rate only 1.5–2 s after onset; (4) drivers shifted their primary visual focus from the start lane to the destination lane immediately after the onset of the lane change. These results will serve as the basis for future development of a new integrated model of driver behavior. 2002 Elsevier Science Ltd. All rights reserved.

Neuronal Mechanisms Underlying Crayfish Steering Behaviour as an Equilibrium Response

ABSTRACT When the crayfish Procambarus is rolled with legs not upon a substratum, uropod opener muscles on the lifted side are activated in co-contraction whereas antagonistic closer muscles on the same side are all relaxed simultaneously. The closers are activated and the openers are relaxed on the lowered side. This reciprocal pattern is also observed in the motor neurone activity: the contraction of opener muscles on the lifted side and closer muscles on the lowered side is caused by an increase in the activity of excitatory motor neurones innervating these muscles, whereas the relaxation of their antagonists on each side is caused by a decrease in the activity of excitatory motor neurones innervating them. Deafferentation by cutting all roots of the terminal ganglion has no significant effect on the steering pattern. The decrease in the excitatory motor neurone activity during steering was found to be due to an increase in the inhibitory input to the motor neurones. During body rolling, the statocyst receptors on the lifted side increase their activity while those on the lowered side decrease it (Takahata & Hisada, 1979). We conclude that the opener motor neurones receive excitation and inhibition respectively from the ipsilateral and the contralateral statocyst, whereas the closer motor neurones receive excitation and inhibition respectively from the contralateral and ipsilateral statocyst. From these results, the connections between the motor neurones and the identified statocyst interneurones were deduced. The normal, bilaterally organized steering pattern of the uropod muscle activity seems to be produced by the statocysts of both sides, whose information is mediated by a bilateral set of interneurones having different connections to individual motor neurones.

A Novel Slots-and-Monopole Antenna with a Steerable Cardioid Pattern

The outputs of a vertical monopole and two mutually perpendicular slots in a horizontal plane can be properly combined to yield a steerable cardioid-shaped pattern for vertically polarized waves. The required weighting factors for placing the pattern null in any desired direction are presented in graphical form. The shape and the half-power beamwidth of the steerable pattern are examined. This combination antenna unit offers important advantages in direction finding and other applications, especially at microwave frequencies.