Array Arrangement Research Articles

Topology-optimized terahertz real-time reconfigurable multifunctional liquid-crystal-coding metasurface

In this paper, a reflective terahertz reconfigurable multifunctional coding metasurface based on topology optimization using liquid crystal (LC) is presented. First, the LC metasurface unit is topologically optimized using the NSGA-II multi-objective optimization algorithm. By applying the bias voltage to dynamically adjust the dielectric constant of the LC, the metasurface unit is capable of 2-bit coding at the frequency of 0.67 THz. Then, based on the designed metasurface unit, the array arrangements of the coding metasurface are reversely designed, which makes the metasurface realize flexible control and dynamic switching between beam assignment and vortex beam generation. The results show that for the beam assignment, the single-beam and multi-beam control can be realized with the reflected electromagnetic waves at continuous arbitrary angles in the range of elevation angle of 40° and azimuth angle of 360°. Moreover, the elevation angle and azimuth angle of each beam in the multi-beam can be controlled independently. Using the Fourier convolution addition operation, the control range of the single-beam elevation angle can be expanded. For the vortex beam, the single vortex beam and the multi-vortex beam can be generated in the range of elevation angle of 40° and azimuth angle of 360° with topological charges l=±1, ±2, ±3 at arbitrary angles. This provides flexibility and diversity in the generation of vortex beams. Therefore, the proposed terahertz LC metasurface can realize flexible control of reconfigurable functions and has certain application prospects in terahertz communication, phased array radar, and vortex radar.

Optimal spatial arrangement of modules for large‐scale photovoltaic farms in complex topography

AbstractThe existing methods for determining the module arrangement in photovoltaic (PV) farms are considered insufficient as they are generally limited to the environment of flat ground without considering both physical and electrical factors. The orientations of PV modules may be very diverse when installed in places with complex topography, e.g. mountains and abandoned mine sites. Thus, the received irradiance by the modules is inconsistent directly results in current differences and hence leads to significant mismatch loss in the PV arrays. This paper proposes a solution to determine the most appropriate combination of tilts and orientations of PV modules as well as the arrangement of PV arrays. The complex topographies are fully considered to minimize the mismatch loss phenomenon, and hence the power generation degradation. The solution adopts a set of models, i.e. the irradiation model for the calculation of optimal module tilts and orientations, the shadow model for shadow effect analysis, and the mismatch model for mismatch condition analysis. A two‐layer multi‐objective optimization is implemented for the optimal arrangement. The proposed solution is assessed through the case study of a 30 MW PV farm. The result confirms the effectiveness of the proposed solution for the optimal spatial module placement.

Effect of soft magnetic particles content on multi-physics field of magnetorheological composite gel clutch with complex flow channel excited by Halbach array arrangement

In this paper we investigate the influence of soft magnetic particle mass fraction on the multi-physics field of proposed magnetorheological (MR) gel clutch. A novel MR gel clutch with complex cup-shaped gap is described, whose performance is based on the relative placement between Halbach array arrangement and MR gel. Smart MR gel with 40 wt%, 50 wt%, 60 wt%, 70 wt% and 80 wt% of soft magnetic particles used as the transfer medium and Halbach array is adopted as magnetic excitation system. Its magnetic/mechanical analysis is carried out based on Bingham-plastics model using COMSOL Multiphysics software, which takes into account the variation of dynamic viscosity with magnetic flux density. The distribution of the magnetic flux density, shear yield stress, post-yield viscosity, shear stress and torque in the four flow channels during the transition from engagement state to disengagement state are obtained and analyzed in detail. Multi-physics field characteristics of proposed MR gel clutch with five kinds of MR gels are studied and compared in order to give some useful suggestions in the design phase. Finally, the dynamic torque of the MR clutch with different MR gel is experimentally evaluated.

Enhancing Signal-to-Noise Ratio in Vehicle-to-Vehicle Visible Light Communication Systems Through Diverse LED Array Transmitter Geometries

In this paper, a novel method is introduced to enhance the performance of vehicle-to-vehicle (V2V) visible light communication (VLC) by employing different transmitter (Tx) light-emitting diode (LED) array arrangements with different LED orientations. Improving the signal-to-noise ratio (SNR) is crucial for V2V VLC systems to provide long communication ranges. For this purpose, six transmitter configurations are proposed: single-LED transmitters, as well as 3 × 3 square-, single hexagonal-, octagonal-, 5 × 5 square-, and honeycomb hexagonal-shaped LED arrays. Indoor VLC studies using LED arrays offer a uniform SNR, while outdoor studies focus on optimizing the receiver side to enhance system performance. This paper optimizes system performance by increasing the SNR and communication range of V2V VLC systems by changing the geometry of the Tx LED array and LED orientations. A V2V VLC system using on–off keying (OOK) is modeled in MATLAB, and the SNR and bit error rate (BER) are simulated for different Tx configurations. Our results show that the honeycomb hexagonal transmitter design provides a 19% improvement in system performance with a spacing of 1 cm, and maintains a 16% improvement when the array size is reduced by a factor of 100, making it smaller than one of the smallest industrial headlight modules.

Optimal Arrangements and Local Anisotropy of {100} Guinier-Preston (GP) Zones by Parametric Dislocation Dynamics (PDD) Simulations.

Stress-oriented precipitation and the resulting mechanical anisotropy have been widely studied over the decades. However, the local anisotropy of precipitates with specific orientations has been less thoroughly investigated. This study models the interaction between an edge dislocation source and {100} variants of Guinier-Preston (GP) zones in Al-Cu alloys using the parametric dislocation dynamics (PDD) method. Concentric geometrically necessary dislocation (GND) loops were employed to construct a line integral model for thin platelets. The simulations, conducted with our self-developed code based on Green's function method and Eshelby inclusion theory revealed distinct strengthening behavior along the strong and weak directions for 60° GP zones, demonstrating anisotropic strengthening from the perspective of elastic interactions. Furthermore, the optimal inclined arrangement of the GP zone array was determined through elastic energy calculations, and these results were corroborated by TEM observations.

Interferometry of ionospheric E-region irregularities based on Kunming VHF radars

There is a long history of using VHF radar systems to detect ionospheric irregularities based on the theory of coherent scattering. According to previous work, there is a high occurrence of field-aligned irregularities (FAIs) in the ionospheric E-region over Kunming, China. In this paper, the VHF coherent scattering radar at Kunming is used to study the FAIs in the ionospheric E-region. Different arrangement of VHF radar antenna arrays, interferometry, and FAI echo parameter inversion methods are designed and tested. The measurement results show that the temporal and spatial characteristics of the irregularities can be obtained using these methods, as well as more refined spatial three-dimensional structure information. It is indicated that the new arrangement of the VHF radar antenna array is feasible to operate interferometry detection of E-region FAIs with the Kunming VHF radar.

Technical note: Computational study on thermal management schemes for tumor-treating fields therapy.

The study focuses on thermal management in tumor-treating fields (TTFields) therapy, crucial for patient compliance and therapeutic effectiveness. TTFields therapy, an established treatment for glioblastoma, involves applying alternating electric fields to the brain. However, managing the thermal effects generated by electrodes is a major challenge, impacting patient comfort and treatment efficiency. This research aims to explore methods for controlling temperature increases during TTFields therapy without reducing its duty cycle. The study emphasizes optimizing electrode configurations and array arrangements to mitigate temperature rise, thereby maintaining therapy effectiveness and patient compliance. Using a simplified multi-layer tissue model and finite element analysis, various electrode configurations and array shapes were tested in COMSOL Multiphysics v6.0. Adjustments included changing the electrode gel layer radius from 8 to 12mm, electrode spacing, and transitioning to a more uniform array arrangement, such as a square array or a circular array. The study revealed a strong correlation between high temperatures and edge current density distributions on electrodes. It was found that increasing the electrode gel layer's diameter, enlarging electrode spacing, and adopting a uniform array arrangement markedly mitigated temperature rises. By increasing the gel layer radius from the original 10 to 12mm, a reduction in the peak temperature increases of approximately 0.3°C was observed. Changing the layout from rectangular to circular with the same area further reduced the peak temperature rise by 0.5°C. Additionally, enlarging the spacing between electrodes also contributed to temperature control. By integrating these strategies, we designed a new circular electrode array with an electrode spacing of 45mm and a gel radius of 12mm, successfully reducing the peak temperature from 42.1°C to 40.8°C, effectively achieving temperature control. The research demonstrates that improving electrode and array configurations can effectively manage temperature in TTFields therapy without compromising treatment duration. This strategy is crucial as TTFields therapy relies on prolonged field exposure for effectiveness. The findings offer valuable insights into thermal management in electrode array design and could lead to enhanced patient compliance and treatment efficacy in TTFields therapy.

3D Light-Direction Sensor Based on Segmented Concentric Nanorings Combined with Deep Learning.

High-precision, ultra-thin angular detectable imaging upon a single pixel holds significant promise for light-field detection and reconstruction, thereby catalyzing advancements in machine vision and interaction technology. Traditional light-direction angle sensors relying on optical components like gratings and lenses face inherent constraints from diffraction limits in achieving device miniaturization. Recently, angle sensors via coupled double nanowires have demonstrated prowess in attaining high-precision angle perception of incident light at sub-wavelength device scales, which may herald a novel design paradigm for ultra-compact angle sensors. However, the current approach to measuring the three-dimensional (3D) incident light direction is unstable. In this paper, we propose a sensor concept capable of discerning the 3D light-direction based on a segmented concentric nanoring structure that is sensitive to both elevation angle (θ) and azimuth angle (ϕ) at a micrometer device scale and is validated through simulations. Through deep learning (DL) analysis and prediction, our simulations reveal that for angle scanning with a step size of 1°, the device can still achieve a detection range of 0∼360° for ϕ and 45°∼90° for θ, with an average accuracy of 0.19°, and DL can further solve some data aliasing problems to expand the sensing range. Our design broadens the angle sensing dimension based on mutual resonance coupling among nanoring segments, and through waveguide implementation or sensor array arrangements, the detection range can be flexibly adjusted to accommodate diverse application scenarios.

Optimization of Sparse Camera Array Arrangement using Grid-based Method

—This study explores the application of multi-camera array technology in super-resolution (SR) imaging system. We propose an innovative method based on grid representation to optimize camera arrangements using sparse Gaussian processes and variational inference. This approach significantly enhances the image reconstruction quality of sparse camera arrays. Unlike conventional techniques that provide only qualitative conclusions, our grid-based method precisely optimizes camera positions and effectively simulates the impact of assembly errors. The optimized camera arrangement substantially improves the SR reconstruction quality of sparse array imaging systems, reducing contour jaggedness and high-frequency aliasing. Extensive simulations and experimental validations confirm the robustness and practical applicability of our method. The results demonstrate that the optimized camera arrangements can achieve high-resolution imaging with enhanced robustness against assembly errors, indicating their potential for various applications such as biological microscopy, remote sensing, and smartphone photography. This work presents a new and effective strategy for designing sparse camera array imaging systems, offering significant improvements in both image quality and system reliability.

Epitaxial Growth of Cs3Cu2I5 Single‐Crystal Arrays for UV‐Responsive Neuromorphic Devices

Copper‐based halides, a type of perovskite derivative, inherit their excellent optoelectronic properties and solution processability and also have the advantages of being nontoxic and stable. Despite the tremendous achievements of microfabrication in conventional halide perovskites, reports on copper‐based halide array devices are rare due to their difficult high‐quality crystallization. Here, by introducing single‐crystal thin films grown by space confinement method as substrates, reliable photolithography based on their single crystals is successfully achieved and controllable homoepitaxial single‐crystal arrays is demonstrated. By adjusting the substrate, angle, and growth time, the orientation, arrangement, and size of arrays could be controlled. Temperature and time are used to regulate the growth stage to obtain clean and appropriately sized arrays. ITO/Cs3Cu2I5/ITO neuromorphic device based on homoepitaxial arrays is developed. The variation of synaptic plasticity could be controlled by the number and frequency of light pulses. The device successfully simulated the process of “learning, forgetting, and relearning” in the human brain, demonstrating the potential of application in sensing‐storage‐computing‐integrated devices.

Performance enhancement of PV array using successive ring adder algorithm based reconfiguration techniques

The photovoltaic array’s output is decreased due to increase of mismatch losses (ML) under partial shading condition. Different row currents begin to flow from the PV modules as a result. Therefore, the panels must be reconfigured to minimize the row current differential in order to get the most power possible from the PV panel. This paper suggests Successive Ring Adder Algorithms (SRAA) to minimize the difference of row current. Under various shading patterns, the proposed scheme’s superiority is evaluated and contrasted with series-parallel (SP) and Total-Cross-Tied (TCT) configurations. The numerical outcomes demonstrate the superiority of the suggested algorithm. Additionally, unlike the recently reported reconfiguration techniques, it may be used with both square (9 × 9) and non-square (9 × 6) PV arrays. In comparison to SP and TCT configuration system, the maximum power generation has improved by 4.04% and 9.25%, respectively. In comparison to TCT (30.96%) and SP (37.52%), the ML was obtained with the lowest value i.e. 25.87%. The efficiency for a 9 × 9 PV array is measured at 13.18%, the highest among TCT (12.67%) and SP (12.07%) configurations. For non-squared (9 × 6) PV array arrangement, similar types of enhanced outcomes are produced.

Interactive effects of deformable wave energy converters operating in close proximity

Flexible wave energy converters (FlexWECs) have been gaining increasing research and industrial interest as their deformable nature can potentially remedy the structural issues that limit the development of rigid WECs. To maximise the usage of space and infrastructure and improve energy efficiency, FlexWECs are normally deployed in close proximity, where the wave interaction with one device can influence others, signifying the opportunity to obtain energy efficiency enhancement from the interactions. To investigate the power capture performance of a FlexWEC array, this study employed a validated three-dimensional high-fidelity computational method to simulate the wave interaction with three FlexWECs in various array arrangements including power-take off. Based on systematic simulation cases, the present work analysed the relation between the geometrical characteristics of an isolated FlexWEC's perturbed wave field and the array's overall energy capture efficiency. The constructive interaction of the array was found the strongest when the longitudinal and lateral spacings of the array were 0.6 and 1 times of incident wavelength respectively, with a 15 % enhancement of overall captured energy compared to three devices operating in isolation. Overall, this study provides insights into the fluid-structure interaction of waves with multiple deformable structures, facilitating the modelling and planning of FlexWECs.

Slot-Loaded Vivaldi Antenna for Biomedical Microwave Imaging Applications: Influence of Design Parameters on Antenna's Dimensions and Performances.

This paper demonstrates the design steps of a slot-loaded Vivaldi antenna for biomedical microwave imaging applications, showing the influence of the design parameters on the antenna's dimensions and performances. Several antenna miniaturization techniques were taken into consideration during the design: reduction in the electromagnetic wavelength by using a high-permittivity substrate material (relative permittivity ϵr=10.2), the placement of the antenna inside a coupling medium (ϵr=23), and the elongation of the current path by etching slots on each side of the radiator to reduce the antenna's lowest resonant frequency without increasing its physical dimensions. Moreover, an analysis of different antenna slot design scenarios was performed considering different slot lengths, inclination angles, positions, and numbers. Considering the frequency range of microwave imaging (i.e., about 500 MHz-5 GHz) and the array arrangement typical of microwave imaging, the best design was chosen. Finally, the antenna was fabricated and its performances in the coupling medium were characterized. The simulation and measurement results showed good agreement between each other. In comparison with literature antennas, the one developed in this work shows wide bandwidth and compact dimensions.

Dual-window polarization filtering characteristics of rectangular photonic crystal fibers

This paper presents a photonic crystal fiber (PCF) polarization filter with a square array arrangement of gold film fillings, allowing for filtering at dual wavelengths. The paper analyzes the dispersion characteristics and loss properties of this structure and optimizes the structural parameters through adjustments to achieve the best performance. At 1310 nm, the confinement losses of x and y polarization fundamental modes are 903.54 dB/cm and 30.51 dB/cm, respectively; at 1640 nm, the confinement losses of y and x polarization fundamental modes are 479.02 dB/cm and 88.72 dB/cm, respectively. The corresponding filtering bandwidths are 390 and 350 nm, while the full width half maximum (FWHM) is 59.56 nm, indicating excellent selectivity and resolution of the filter. The performance metrics, such as confinement loss, extinction ratios, and bandwidth, are compared in the paper with those reported for other filters. Additionally, the study also analyzed the filter’s performance under varying manufacturing tolerances of gold film thickness and air hole diameter by 5%, revealing that the filter’s performance remains stable and feasible even in the presence of errors.

Microneedle Optimization: Toward Enhancing Microneedle's Functionality and Breaking the Traditions

Microneedles hold remarkable potential for providing convenient and unique solutions for disease diagnosis and therapy. However, their integration into clinical practices has been slow, primarily due to the challenge of developing models that meet the criteria of a particular application. A comprehensive and systematic analysis of all aspects of microneedle platforms is imperative to overcome this bottleneck. The analysis involves gathering performance‐related information and understanding the factors affecting the functionality of microneedles. The performance of microneedles is heavily influenced by parameters such as dimensions, needle shape, array arrangement, and materials (flexible, stretchable, stimuli‐responsive, biodegradable). This article presents a fresh perspective on microneedles, introducing concepts toward optimal designs across various microneedle platforms. This includes application, design, fabrication techniques, and understanding how a specific microneedle design can effectively meet the requirements of a particular application. By addressing these crucial issues, further advancement of microneedle technology occurs.

An experimental study on improving the thermal environment of data centers by optimizing fan wall arrangement

For a fan-wall data center, a large number of fans can be installed on one side of the server room to facilitate the introduction of outdoor cold air into the server room for effective heat dissipation, thereby accomplishing the objective of energy conservation. However, fewer researches are currently available on optimizing the fan array layout of fan-wall data centers to improve the thermal environment. This study aims to explore the impact of fan array layout parameters, including the area, distance, and height of the fan array, on the cooling efficiency of server rooms through both single-factor experiments and orthogonal experiments. The results indicate that: (1) In a fan-wall cooling system, racks closest to the fan wall have high temperature fluctuations and less orderly airflow organization. (2) The optimization of the fan array layout in a data center is primarily influenced by the height, area and distance of the fan array. (3) For a DC, the fan array layout, with an area of 4320 cm2, a distance of 81 cm, and a height of 18 cm, can achieve optimal conditions and effectively enhances the overall thermal performance of the rack. By optimizing the layout of the fan array, a more efficient combination of parameters for air distribution can be achieved, providing a reference for the arrangement and layout of fan arrays in actual engineering applications.

A quad-port triple-band high isolation terahertz MIMO antenna for short-distance THz communication links

This paper introduces an arrangement of a Multiple-Input Multiple-Output antenna array implemented specifically for operating within the THz frequency bands. The antenna is designed for short-distance THz communication links. A quad-port MIMO antenna configuration has been chosen to function across three frequency bands. Each cell element is situated on top of a silicon substrate. The combined cross-sectional surface of the MIMO antenna is 70 × 50 µm². The proposed MIMO antenna device reaches the following three frequency bands: 2.6–7.9 THz, 9.66–10.3 THz and 11.5–14.1 THz. In addition, the mutual coupling coefficient is less than − 20 dB, indicating strong isolation between antenna elements. This high isolation is obtained by using a defected sibstrat structure and a specifique distance between antenna elements. The MIMO array antenna attains peak gains of 11.88 dBi, 8.78 dBi and 10.65 dBi when operating over the three cited bandwidth. Furthermore, the suggested MIMO structure exhibits favorable characteristics with CCL < 0.5 bps/Hz/sec, MEG ≤ –3.0 dB, ECC < 0.01, and DG ≈ 10 dB, over the operating bands. Based on the results obtained and compared to several works reported in the literature, the proposed implementation maintains a good size-performance compromise which allows better adaptation to applications requiring versatile performance in various communication scenarios.

Study of Partial Shading Effect on the Different Photovoltaic Array Arrangements and their Shade Resilience

Due to its ability to directly and cleanly convert solar radiation into electricity, the use of photovoltaic (PV) technology is rapidly increasing. Solar PV panels are connected in various series and parallel configurations to achieve the necessary output voltages and currents. They perform optimally when completely unshaded, but when a series connection is partially shaded (PS), bypass diodes activate and the overall voltage drops, resulting in reduced power generation. The location of bypass diodes, series-parallel combination types, and shading patterns all impact the output power. Therefore, selecting the appropriate PV panel arrangement can potentially increase output under these conditions. This study analyzes the shade resilience ability of series-parallel (SP), Total cross-tied (TCT), Bridge-linked (BL), and Honeycomb (HC) configurations.

On the prediction of the turbulent flow behind cylinder arrays via echo state networks

This study aims at the prediction of the turbulent flow behind cylinder arrays by the application of Echo State Networks (ESN). Three different arrangements of arrays of seven cylinders are chosen for the current study. These represent different flow regimes: single bluff body flow, transient flow, and co-shedding flow. This allows the investigation of turbulent flows that fundamentally originate from wake flows yet exhibit highly diverse dynamics. The data is reduced by Proper Orthogonal Decomposition (POD) which is optimal in terms of kinetic energy. The Time Coefficients of the POD Modes (TCPM) are predicted by the ESN. The network architecture is optimized with respect to its three main hyperparameters, Input Scaling (INS), Spectral Radius (SR), and Leaking Rate (LR), in order to produce the best predictions in terms of Weighted Prediction Score (WPS), a metric leveling statistic and deterministic prediction. In general, the ESN is capable of imitating the complex dynamics of turbulent flows even for longer periods of several vortex shedding cycles. Furthermore, the mutual interdependencies of the TCPM are well preserved. However, optimal hyperparameters depend strongly on the flow characteristics. Generally, as flow dynamics become faster and more intermittent, larger LR and INS values result in better predictions, whereas less clear trends for SR are observable.

Effect of array arrangement on acoustic levitation performance

Effect of array arrangement on acoustic levitation performance