Distributed Array Research Articles

Numerical investigation on the heat transfer of particle arrays in supercritical water

The heat transfer characteristics of particles in supercritical water (SCW) are the research foundation for the development of the technology of coal gasification in SCW. The study encounters two challenging problems: the complexity of particle spatial distribution and the special variation of SCW properties. Therefore, this work focuses on contrasting the particle interaction characteristics between in SCW and conventional fluid, instead of the direct study of particle clusters in SCW. Research is conducted by the particle-resolved numerical simulation method. In the simulations, the SCW inflow is 973 K and 25 MPa which is a usual operating condition, and all particle surface temperatures are constant and uniform with the values of 300 K, 672 K and 973 K which are respectively below, at and beyond the pseudocritical temperature zone. The side-by-side and streamwise distributed arrays, which are simple but representative, are adopted as the research objects firstly. The effects of particle number and inter-particle distance on heat transfer are studied. Results indicate that the effects of particle interaction on heat transfer under all heat transfer states are similar in the side-by-side array; while only the effects under the pseudocritical and supercritical states are similar in the streamwise array. Then the structured packed array is adopted, and the effects of void fraction (ε) under different heat transfer states are studied. Moreover, a new correlation dependent on ε and Re is built for predicting the ratio of the Nu of a particle in the structured packed array and that of a single particle.

A Direct Position Determination Method under Unknown Multi-Perturbation with Moving Distributed Arrays

Distributed array manifold perturbation, which includes synchronization errors, amplitude-phase errors, and path attenuation, has seriously degraded the accuracy of existing direct position determination (DPD) methods. In this paper, a DPD method under unknown multi-perturbation with moving distributed coprime arrays is advocated for. Firstly, by means of array position interchange, the integrated signals received from distributed arrays can be fused, which contributes to multi-position fusion. Subsequently, by resorting to the orthogonality between the noise subspace and steering vector received via distributed arrays, a quadratic optimization problem is constructed. Finally, we realize multi-parameter decoupling and achieve localization regardless of unknown perturbations. The superiority of the advocated method is substantiated from simulation examples.

Study of Pressure Distribution in Floor Tiles with Printed P(VDF:TrFE) Sensors for Smart Surface Applications

Pressure sensors integrated in surfaces, such as the floor, can enable movement, event, and object detection with relatively little effort and without raising privacy concerns, such as video surveillance. Usually, this requires a distributed array of sensor pixels, whose design must be optimized according to the expected use case to reduce implementation costs while providing sufficient sensitivity. In this work, we present an unobtrusive smart floor concept based on floor tiles equipped with a printed piezoelectric sensor matrix. The sensor element adds less than 130 µm in thickness to the floor tile and offers a pressure sensitivity of 36 pC/N for a 1 cm2 pixel size. A floor model was established to simulate how the localized pressure excitation acting on the floor spreads into the sensor layer, where the error is only 1.5%. The model is valuable for optimizing the pixel density and arrangement for event and object detection while considering the smart floor implementation in buildings. Finally, a demonstration, including wireless connection to the computer, is presented, showing the viability of the tile to detect finger touch or movement of a metallic rod.

Formation-of-Arrays Antenna Technology for High-Throughput Mobile Non-Terrestrial Networks

Effective integration of terrestrial and non-terrestrial segments is one of the key research avenues in the design of current and future wireless communication networks. To this aim, modern communication-satellite constellations intend to attain sufficiently high throughput in terms of bit rate per unit area on the ground by rather aggressive patterns of spatial frequency reuse. This goal calls for on-board narrow-beam antennas, whose size turns out to be in many cases incompatible with the size/mass and accommodation constraints of the hosting satellite. This paper investigates the attainable performance of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">large distributed arrays of antennas</i> implemented as the ensemble of a few to many simpler sub-antennas of smaller sizes, carried by one (small) satellite each. The sub-antennas can in their turn be implemented like (regular) 2D arrays of simple radiating elements, realizing an overall (distributed) antenna architecture that we call “formation of arrays” (FoA). The satellites that implement this radiating architecture need to be relatively close to each other and constitute a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">formation</i> of flying objects, to be coordinated and controlled as a whole. In this paper, we develop a theoretical analysis of an FoA antenna, and we show how to take advantage of this new technology to improve network throughput in a multi-beam S-band mobile communication network with low-earth or geostationary orbiting satellites directly providing 5G-like communication services to hand-held user terminals.

Влияние расположения затопленных импактных микроструй на конвективный теплообмен при охлаждении теплонапряженной поверхности водой и диэлектрической жидкостью

Heat transfer during cooling of a heat-stressed surface in a small-sized channel by an annular and distributed array of flooded impact microjets of water and dielectric liquid Novec 7100 has been experimentally studied. The experimental setup is a copper block cooled by an array of microjets from nozzles with a diameter of 174, 327 μm and located at a distance of 1 mm from the surface. It has been established that the use of localized arrays of microjets makes it possible to obtain effective cooling of a heat-stressed surface with pumping energy comparable to energy costs for distributed microjets.

Influence of location of submerged impact microjets on convective heat transfer during cooling of a heat-stressed surface by water and dielectric liquid

Heat transfer during cooling of a heat-stressed surface in a small-sized channel by an annular and distributed array of flooded impact microjets of water and dielectric liquid Novec 7100 has been experimentally studied. The experimental setup is a copper block cooled by an array of microjets from nozzles with a diameter of 174, 327 μm and located at a distance of 1 mm from the surface. It has been established that the use of localized arrays of microjets makes it possible to obtain effective cooling of a heat-stressed surface with pumping energy comparable to energy costs for distributed microjets. Keywords: convective heat transfer, impact microjet, water, dielectric liquid.

The electric field cavity array effect of 2D nano-sieves

For the upsurge of high breakdown strength ({{{{{{rm{E}}}}}}}_{{{{{{rm{b}}}}}}}), efficiency ({{{{{rm{eta }}}}}}), and discharge energy density ({{{{{{rm{U}}}}}}}_{{{{{{rm{e}}}}}}}) of next-generation dielectrics, nanocomposites are the most promising candidates. However, the skillful regulation and application of nano-dielectrics have not been realized so far, because the mechanism of enhanced properties is still not explicitly apprehended. Here, we show that the electric field cavity array in the outer interface of nanosieve-substrate could modulate the potential distribution array and promote the flow of free charges to the hole, which works together with the intrinsic defect traps of active Co3O4 surface to trap and absorb high-energy carriers. The electric field and potential array could be regulated by the size and distribution of mesoporous in 2-dimensional nano-sieves. The poly(vinylidene fluoride-co-hexafluoropropylene)-based nanocomposites film exhibits an {{{{{{rm{E}}}}}}}_{{{{{{rm{b}}}}}}} of 803 MV m−1 with up to 80% enhancement, accompanied by high {{{{{{rm{U}}}}}}}_{{{{{{rm{e}}}}}}} = 41.6 J cm−3 and {{{{{rm{eta }}}}}},≈ 90%, outperforming the state-of-art nano-dielectrics. These findings enable deeper construction of nano-dielectrics and provide a different way to illustrate the intricate modification mechanism from macro to micro.

Late 2022 Wellbeing studies in Aotearoa New Zealand

In November 2022 Treasury released its Te Tai Waiora report on well-being, together with a considerable suite of supporting pa pers. These include a conceptual framework and measuring system concerning ‘Living Standards framework’ (LSF) which has been under development for several years with the measurement system now populated with the most recently available statistics (mainly up to 2021). The main report reviews NZ’s wellbeing in terms of the array of trends and social distributions of many of the indicators organised in terms of the LSF, with the series of supporting papers fleshing out more details for much of the coverage. Included amongst these papers is a thorough description of the wellbeing of NZ society and its major subpopulations, with particular attention devoted to the recent impacts of the Covid pandemic. Of recent months Treasury’s work has been accompanied with the release of MSD’s social cohesion baseline report and the MSD survey of young New Zealanders, and comments on these are added to the commentary provided.

Nonlinear dispersion properties of metamaterial beams hosting nonlinear resonators and stop band optimization

The nonlinear dispersion properties of a metamaterial beam embedding nonlinear resonators are investigated. The metamaterial beam incorporates a distributed array of local resonators exhibiting softening or hardening cubic nonlinearity. The nonlinear dynamic behavior of the metamaterial beam is first investigated asymptotically via the method of multiple scales, which yields the closed-form nonlinear dispersion functions with the associated stop bands and the nonlinear dispersive waves as a combination of acoustic and optical bending waves. The effects of the resonators nonlinearity and the hosting beam nonlinear bending curvature on the stop bands are investigated in terms of sensitivity with respect to the strength and type of resonators nonlinearity. A full multi-variable optimization is carried out to study the nonlinear stop band size variations with respect to the resonators nonlinearity and the acoustic/optical wave amplitudes. The results show how the exploitation of the nonlinearities offers great possibilities to enlarge the size of the stop bands compared to the corresponding linear case and, hence, greatly enhance the energy absorption bandwidth.

Manifold learning for dynamic array geometries

Large-scale distributed arrays can obtain high spatial resolution, but they typically rely on a rigid array structure. If we want to form distributed arrays from mobile and wearable devices, our models need to account for motion. The motion of multiple microphones worn by humans can be difficult to track, but through manifold techniques we can learn the movement through its acoustic response. We show that the mapping between the array geometry and its acoustic response is locally linear and can be exploited in a semi-supervised manner for a given acoustic environment. We will also investigate generative modelling of microphone positions based on their acoustic response to both synthetic and recorded data. Prior work has shown a similar locally linear mapping between source locations and their spatial cues, and we will attempt to combine these findings with our own to develop a localization model suitable for dynamic array geometries.

Passive distributed arrays cross-location algorithm with windowed deconvolution

To eliminate the appearance of false peaks in underwater passive distributed cross-location, a cross-location algorithm with windowed deconvolution in the spatial domain is proposed. The algorithm can effectively detect and locate passive targets and effectively eliminate passive cross-location false peaks. First, the windowed deconvolution algorithm is applied in an integral form to individual narrow sub-band spatial spectra. The spatial spectra are summed to obtain the broadband spatial energy spectrum. The estimated propagation loss and the one-dimensional broadband energy spectrum are used to deduce the sound source level of the two-dimensional scanning grid points. In the proposed method, the mean value and standard deviation of the source level are inversely deduced using multiple arrays, and the standard deviation is used to weight the fusion result for each scan point to weaken the energy output corresponding to the false position. Simulation results show that the algorithm can effectively detect and locate targets in the presence of strong interference. The crossover result for the energy line shows that ambiguity to the left and right side of the line array is overcome.

Real Time Water Pollution Monitoring RC Boat Using IOT

Nowadays drinking water is the most precious and valuable for all the human beings, drinking water utilities faces new challenges in real-time operation. This challenge occurred because of limited water resources growing population, ageing infrastructure etc. Hence therefore there is a need of better methodologies for monitoring the water quality. Traditional methods of water quality involve the manual collection of water sample at different locations, followed by laboratory analytical techniques in order the character the water quality. Such approaches take longer time and no longer to be considered efficient. Although the current methodologies analysis the physical, chemical and biological agents, it has several drawbacks: a) poor spatiotemporal coverage b) it is labor intensive and high cost(labor, operation; and equipment) c)the lack of real time water quality information to enable critical decisions for public health protection. Therefore, there is a need for continuous online water quality monitoring. The online water monitoring technologies have made a significant progress for source water surveillance and water plant operation. The use of their technologies having high cost associated with installation and calibration of a large distributed array of monitoring sensors. The algorithm proposed on the new technology must be suitable for particular area and for large system is not suitable.

Generation of a coherent distributed RF array with a strong positive correlation.

In this work, we present a coherent distributed radio frequency (RF) array, discover and quantitatively describe the strong positive correlation between reconstructed signals for the first time. Eight replicable parallel receivers are connected to the phase-locked common trunk link via eight optical couplers spaced 1 km apart. The forward and backward signals at each receiver, extracted from two ports of optical couplers, are recovered to RF signals separately and then mixed to achieve upward frequency conversion. The link delay jitter is counteracted by wavelength-tuning of the optical carrier. With the long-term stability of point-to-multipoint fiber-optic RF dissemination effectively improved, the coherent distributed array is generated, and further the relative frequency stability between signals at different receivers is studied. The proposed correlation coefficient at 103 s is ∼0.8 and shows a slight downward trend with the increase of averaging time based on our experimental results.

Distributed fault detection and isolation in time‐varying formation tracking UAV multi‐agent systems

AbstractThe problem of distributed fault detection and isolation (DFDI) in conjunction with time‐varying formation control of unmanned aerial vehicle (UAV) multi‐agent systems with multiple‐leader leader–follower structure is studied, in this paper. It is assumed that the communication data of the agents are noisy, and faults may occur in either leaders or followers. The followers are not aware of the main trajectory and just follow the leaders. The first step in this paper is to reduce the communication noise. Besides, if a fault occurs in one of the leaders causing to exit the leader from the main trajectory, the followers should be able to detect the fault, isolate the leader, use the other leaders' data, and keep the main trajectory. Tracking the trajectory by followers in such a case is the second step of this paper. Preserving the time‐varying formation despite a fault occurring in one of the followers is the next step. To reach these goals, a distributed array of Kalman filters is used for noise cancellation and data extraction. Next, the combination of state vector data fusion and some type of 2 test are employed for DFDI, in agents. Besides, a controller is implemented in each agent for formation tracking. In this controller, estimated relative position and velocity vectors of the agents are employed to keep the time varying formation while tracking the leaders. The closed‐loop stability is studied via Lyapunov stability theorem, and various simulations are carried out to demonstrate the capability of the proposed strategy.

Experimental Investigation of Large Area Subwavelength Cavity Antennas With Planar Metamaterials

We experimentally investigated the large area subwavelength cavity antenna with artificial permeability-negative metamaterials in the GHz region. It is demonstrated that this new type of planar metamaterials has better directivity and higher gain with the radiation source using the large non-uniform distributed patch array than using a uniform distributed patch array, where the current distribution of the radiation source satisfies the Chebyshev distribution. The experimental values agreed well with simulated results. This new metamaterial antenna has potential applications in weak microwave signal detection and radio observation fields.

Two-Dimensional Beam Pattern Synthesis for Phased Arrays With Arbitrary Element Geometry via Magnitude Least Squares Optimization

In this paper, an optimization procedure for synthesizing shaped beams with an arbitrary geometry phased array system with real-time capability is presented. The algorithm involves a combination of an arbitrary extension of the Woodward-Lawson synthesis procedure with the magnitude least-squares optimization method. This simple combination significantly reduces the optimization time, enabling real-time beam shaping in response to changing requirements on beam shape or evolving geometry in distributed arrays. The technique places no restrictions on element positioning in all three spatial dimensions and is demonstrated to accurately reproduce the desired beam shape in both angular dimensions. The algorithm is demonstrated for multiple beam cases with a large, randomly generated array in computational simulation. The applicability of the algorithm to practical phased array hardware is also demonstrated using full-wave electromagnetic simulations and measurements of a realized arbitrary phased array system using a near-field scanner in an anechoic chamber.

Effect of Surface Morphology Changes on Optical Properties of Silicon Nanowire Arrays.

The optical properties of silicon nanowire arrays (SiNWs) are closely related to surface morphology due to quantum effects and quantum confinement effects of the existing semiconductor nanocrystal. In order to explore the influence of the diameters and distribution density of nanowires on the light absorption in the visible to near infrared band, we report the highly efficient method of multiple replication of versatile homogeneous Au films from porous anodic aluminum oxide (AAO) membranes by ion sputtering as etching catalysts; the monocrystalline silicon is etched along the growth templates in a fixed proportion chemical solution to form homogeneous ordered arrays of different morphology and distributions on the surface. In this system, we demonstrate that the synthesized nanostructure arrays can be tuned to exhibit different optical characteristics in the test wavelength range by adjusting the structural parameters of AAO membranes.

Design and Analysis of Multi-Mode Distributed Array with Hybrid Optimization Method

In this paper, we presented an improved hybrid optimization method to construct distributed array with two identical sub-arrays, which is mainly applied on airplanes as the front-end of communication and detection system. According to different demands on array’s gain and operating distances, the proposed method presents a scheme of implementation of two operate modes by optimizing elements’ positions and excitations. Two sub-arrays are able to work together to realize high gain when the object is quite far away, and one sub-array is able to work alone when the object is relatively close. This method is presented based on Particle Swarm Optimization (PSO) method and convex method, accomplishing that peak sidelobe level (PSLL) of whole array is lowered under -10 dB, and PSLLs of sub-arrays are lowered under -20 dB by supplementing some auxiliary units and re-optimizing array’s excitation distribution. In the procedure of optimization, the hybrid method is designed catering to multiple constraints according to the requirements of practical application. A specific example for synthesizing reconfigurable distributed array is provided and the sensitivity of obtained performance affected by interference of optimized results is discussed.

Performance Analysis of Nonuniformly Arranged Array With Position Errors

In this letter, focusing on the diversity of position error generation of distributed array with different interelements’ distances, we presents a number of mathematic models of position error to give further analysis on performance of optimized distributed array. Proposed models define a tolerance analysis tool to research the uncertainties of nonuniform array’s pattern with position errors. A set of representative numerical experiments are reported and discussed to point out the effectiveness and accuracy of proposed error models. Position error tolerance of distributed array is also researched to give specific error limitation under certain demand on performance. Meanwhile, with the study of position error tolerance, it is helpful to make performance analysis of optimized distributed array with position errors more precise.

Distributed Sound Transmission and Smart City Planning Management Based on Convolutional Neural Network

In this article, we provide a detection method based on a convolutional neural network algorithm. Preamble detection is very important in underwater acoustic communication. Only the preamble signal can trigger the receiving operation to effectively process the acoustic data received underwater. The prerequisite for specifying the joint position of the distributed acoustic multiarray is the mutual calibration calculation of each array. This paper designs and develops a prototype system for microphone array sound source positioning and provides an optimized system to obtain calibration source mapping points for distributed sound transmission mutual calibration, and for mutual distributed acoustic microphone arrays, use epipolar geometry and normalization algorithm for calibration to provide a basis for a mutual calibration calculation model and functional module design. Finally, perform numerical simulation verification. It provides a design plan and implementation method for the Internet-based smart city education system, aiming to achieve professional education and educational needs related to the Internet of Things. First, we will take Internet application technology as an example to analyze the functional requirements of the education system, including the positioning of human resource development, integrated sensors, C/C#/Java application development technology, and other technical means to realize the smart city education system. Based on the theory of business management, this paper studies the business planning issues of smart city construction. The main content is divided into three parts: business composition and management and planning management. This is an important part of business. It plays a decisive role in the overall planning and implementation stage and protects the implementation progress of the project and ensures the quality of the project by including important content.