Distributed genetic algorithm for optimal planar arrays of aperture synthesis telescope

Sparse arrays of telescopes have a limited (u, v)-plane coverage. In this paper, an optimization method for designing planar arrays of an aperture synthesis telescope is proposed that is based on distributed genetic algorithm. This distributed genetic algorithm is implemented on a network of workstations using community communication model. Such an aperture synthesis system performs with imperfection of (u, v) components caused by deviations and(or) some missing baselines. With the maximum (u, v)-plane coverage of this rotation-optimized array, the image of the source reconstructed by inverse Fourier transform is satisfactory.

4-ELEMENT PLANAR ARRAY ANTENNA FOR UWB APPLICATION

A novel low-cost 4-element planar array antenna directly fed by a coaxial cable for Ultra-WideBand(UWB) application is presented. The proposed antenna consists of 2×2 bowtie elements and a simple 1:4 power divider feeding network. Compared to the basic bowtie element, the impedance bandwidth of the array antenna has a significant improvement that the low cut-off frequency is extended from 6 GHz of the bowtie element to 2 GHz. The measured results show that the proposed antenna has a large bandwidth of 2 GHz to 11 GHz for Voltage Standing Wave Ratio(VSWR)<2, and exhibits a bidirectional radiation pattern and a modest gain across the operating band and a peak gain of about 9 dBi at 11 GHz.

Investigation of the Resistance and Inductance of Planar Wire Array Z-Pinch at the Qiangguang Accelerator

The resistance and inductance of a wire array during an implosion are very important parameters of interest to：researchers. A variety of inductances and resistances directly affect the kinetic energy and resistance heat energy coupled from a pulsed-power generator. In this paper, the inductance and resistance of a planar wire array during the Z-pinch process are analyzed. The inductance is calculated from the data obtained by a time-resolved soft X-ray framed camera, while the resistance is calculated through the voltage and the current of the wire array load combined with the variety of the inductance. The results show that the resistance of the load increases with the development of the implosion, and reaches its maximum at 0.29 ± 0.16Ω near the pinched time.

Two dynamics modes in planar wire array Z pinch implosion

Two dynamics modes, named short ablation mode and long ablation mode, are observed in implosion experiments of planar wire array Z pinch on ＇QiangGuang-I＇ facility utilizing an optical streak camera. The long ablation mode has a lagged trajectory compared with the short ablation mode. For shot 10035 in a short ablation mode, the initial time of K-shell radiation is consistent with the interaction time for ablation plasma arriving at the centre of wire array, while for shot 10038 in long ablation mode, the initial time of K-shell radiation is about 10 ns earlier. In the two modes, the partial ablation plasma could traverse the wire array plane and then collide in the centre to form a dense plasma column with a diameter of 2.2 mm for shot 10035 and 1.5 mm for shot 10038.

Optimal Design of Improved L-shaped Coprime Array Based on Difference and Sum Co-array

The concept of difference and sum co-array(DSCA)has become a new design idea for planar sparse arrays.Inspired by the shifting invariance property of DSCA,a specific configuration named here as the improved L-shaped array is proposed.Compared to other traditional 2D sparse array configurations such as 2D nested arrays and hourglass arrays,the proposed configuration has larger central consecutive ranges in its DSCA,thus increasing the DOF.At the same time,the mutual coupling effect is also reduced due to the enlarged spacing between the adjacent sensors.Simulations further demonstrate the superiority of the proposed arrays in terms of detection performance and estimation accuracy.

2D Augmented Coprime Array Geometry Based on the Difference and Sum Coarray Concept

The concept of difference and sum(diff-sum)coarray has attracted a lot of attentions in the estimation of direction-of-arrival(DOA)for the past few years,due to its high degrees-of-freedom(DOFs).A vectorized conjugate augmented MUSIC(VCA-MUSIC)algorithm is applied to generate an equivalent signal model which contains the virtual sensor positions of both the difference and sum of the physical sensors in the two-dimensional(2D)arrays,by utilizing both the spatial and temporal information.Besides,an augmented 2D coprime array configuration is presented with the basis on the concept of difference and sum coarray.By compressing the inter-element spacing of one subarray and introducing the proper separation between the two subarrays of 2D coprime array,the redundancy between the difference coarray and the sum one can be reduced so that more virtual sensors in both coarrays can make contributions to the DOFs.As a result,a much larger consecutive area in the diff-sum coarray can be achieved,which can significantly increase the DOFs.Numerical simulations verify the superiority of the proposed array configuration.

Adaptive Uniform Circular Array Synthesis Using Cuckoo Search Algorithm

Naturally suited array geometry for 360&deg; coverage is the uniform circular array (UCA). A comparison of two types of uniform circular array configurations is presented in this paper. Due to its symmetrical geometry UCA is always targeted which results in minimal change inside lobe levels and beam width when scanned by a phased array antenna. Particle Swarm Optimization and Cuckoo algorithm are used for the calculation of complex weights of the array elements. Comparisons are drawn in the context of adaptive beam forming capabilities. Obtained results suggest that planar uniform circular array (9:10) using Cuckoo algorithm, has better beam forming properties with also reduced side lobe levels when compared to other geometry.

Performance Analysis of Intelligent Reflecting Surface Assisted Wireless Communication System

In this paper,we investigate the end-to-end performance of intelligent reflecting surface(IRS)-assisted wireless communication systems.We consider a system in which an IRS is deployed on a uniform planar array(UPA)configuration,including a large number of reflecting elements,where the transmitters and receivers are only equipped with a single antenna.Our objective is to analytically obtain the achievable ergodic rate,outage probability,and bit error rate(BER)of the system.Furthermore,to maximize the system’s signal-to-noise ratio(SNR),we design the phase shift of each reflecting element and derive the optimal reflection phase of the IRS based on the channel state information(CSI).We also derive the exact expression of the SNR probability density function(p.d.f.)and show that it follows a non-central Chi-square distribution.Using the p.d.f.,we then derive the theoretical results of the achievable rate,outage probability,and BER.The accuracy of the obtained theoretical results is also verified through numerical simulation.Itwas shown that the achievable rate,outage probability,and BER could be improved by increasing the number of reflecting elements and choosing an appropriate SNR regime.Furthermore,we also find that the IRS-assisted communication system achieves better performance than the existing end-to-end wireless communication.

Thinned array antenna synthesis using modified binary particle swarm optimization with minimization of sidelobes

Purpose-The purpose of this paper is to propose radiating system by avoiding electromagnetic interference in unwanted directions and to radiate the energy in the required direction with an optimization technique.Design/methodology/approach-Practically,multiple,incompatible variables require concurrent boost on a synthesis of systematic antenna assemblage.The authors have worked out the main statistic penalty function to ensure all the restrictions.Here,MBPSO(Modified Binary Particle Swarm Optimization)is developed and introduced thin planar synthesis restriction.The sigmoid function is used to update the particle position.Different analytical demonstrations have been carried out,and the exhibited methods are predominant than the algorithms.Findings-A 20310 planar antenna array is synthesized using modified BPSO.The authors have suppressed the PSLL in two principal planes and as well as in the entire f plane.Numerical results state that MBPSO outperforms the other binary BPSO,BCSO,ACO,RGA,GAoptimization techniques.MBPSO achieved a
51.84 dB PSLL level,whereas BPSO achieved
48.57 dB with the same 50%thinning.Originality/value-Planar array antenna formation is one of the most complex syntheses because the array gets filled with more antenna elements.The machine-like complication and implementation of such an antenna arrangement with a broad opening would be expensive.It is not easy to control the required radiation patterns shape by using a uniform feeding network.To get better flexibility for sustaining the sidelobe levelheaded along with consistent amplitude distribution.So as far as prominence has been given to the evolutionary algorithm,find an ideal solution for objective array combinational problems.

Landing noise of aircraft based on the fly-over measurements with a planar microphone array

A large planar microphone array, which consists of 111 microphones, was successfully developed. The positions of 111 microphones in the array were determined by a random optimization procedure for the largest possible amplification and dynamic range. The beam pattern of planar array was obtained by numerical calculation. This planar array was applied to measure a two-dimensional mapping of the sound sources on landing aircraft. It is shown that important airframe noise sources can be identified. The spectra and directivity of any interested noise source can also be obtained by this measurement.

Fast UV-vis-NIR photoresponse of self-oriented F_(16)CuPc nanoribbons

Controlling the vapor-deposited nanoribbons to grow along a consistent orientation will enable the desired in situ integration of functional devices,representing a major technological advance compared to post-growth processing strategies.In this work,ntype F_(16)CuPc molecules are self-assembled into horizontally-oriented nanoribbons with a consistent growth axis after creating periodic hydrophobic nanogrooves on a sapphire surface.Consequently,electrodes are deposited directly on the growth substrate to enable in situ fabrication of photodetectors.Depending on the deposited electrodes,these horizontally-oriented nanoribbons are connected to form a monolithic photodetector with a large sensing area or an on-chip array of photodetectors with multiple detector units.This in situ integration strategy avoids potential structural damage and contamination from impurities associated with post-growth processing steps.Therefore,the vapor-deposited nanoribbons can retain their high quality during the device manufacturing process,which contributes to performance improvement.As a result,the in-situ integrated F_(16)CuPc photodetectors exhibit a sensitive response in the ultraviolet-visible-near-infrared(UV-vis-NIR)region.The response time is on the order of tens of milliseconds,the fastest record ever for the F_(16)CuPc-based photodetectors.Furthermore,statistics from an array of 6×6 photodetectors show little variation in their sensitivity and response time,and hence this in situ fabrication scheme will contribute to the implementation of on-chip integrated photodetectors with consistent performance based on bottom-up nanoribbons.Overall,this self-oriented growth provides a versatile option to achieve desired in-situ integrated functional devices based on bottom-up nanoribbons.