Phase Of Element Research Articles

Design of an Orthotropic Piezoelectric Composite Material Phased Array Transducer for Damage Detection in a Concrete Structure

ABSTRACTIn order to verify the feasibility and effectiveness of the sensor used in complex concrete materials, an innovative application of ultrasonic phased array detection for a concrete structure was investigated. Comparing with the traditional piezoelectric composites, orthotropic piezoelectric composite material (OPCM) can be used as transducers in damage detection show clear advantages because of their high sensitivity and directivity along the polarization direction. A low frequency ultrasonic phased array transducer consisting of 16 OPCM elements is studied. The optimal array parameters, such as the phased array element interval, the array element width, and number of elements, are obtained by studying the total displacement changes as various parameters change at the focus point in the concrete structure. This configuration allowed the variation and control of the wave field directivity in the concrete structure during the measurements. The measurements were taken on concrete specimens using a precise time-delay device. The experimental measurements were compared to theoretical calculations to investigate the influence of different array element parameters. The results show that an OPCM phased array transducer can be used to detect damage in a concrete block.

Additive process for fabrication of phased optical diffraction elements

We describe a process for fabrication of optical diffraction elements based on localized thermochemical oxidation of a thin chromium film. Once the recording procedure has been completed, the unoxidized chromium is removed, thereby forming a microrelief consisting of transparent chromium oxide.

Full Matrix Capture 기법을 통한 초음파신호 영상화 향상 연구

Abstract A conventional phased array system can control an ultrasonic beam electronically by adjusting the excitation time delay of individual elements in a multi-element probe and produce an ultrasonic image. In Contrast, full matrix capture (FMC) is a data acquisition process that allows receiving ultrasonic signals from one single shot of the phased array transducer element through all the other elements and captures the complete dataset from every possible transmit-receive combination. This FMC data can be used to create the ultrasonic image in post processing. It is possible to produce not only images equivalent to conventional phased array image but also total focusing method (TFM) images with improved resolution and sharpness, which is virtually focused at any point in a region of interest. In this paper, the system that can perform FMC by using a conventional phased array instrument is developed, and a study was conducted on the imaging algorithms to reconstruct sector B-scan and TFM images from FMC dataset.

Effective Height, Receiving Area, and Receiving Efficiency of Infinite Planar Phased Array Elements

For infinite planar phased array elements, a vector effective height is determined and the receiving area and receiving efficiency are found in terms of transmitting performance descriptors. The vector effective height allows the open-circuit received voltage to be expressed as an inner product with the incident electric field, as is for an isolated antenna. Generalizing a previously known expression, the effective area is expressed in terms of polarization mismatch, radiation efficiency, impedance mismatch, and the projected unit cell area, together with the element Floquet directivity introduced in this study that quantifies the unidirectional or bidirectional nature of radiation. An element's total receiving efficiency is defined and its expression is inspected for maximizing the received power.

Virtual Phase Shifter Array and Its Application on Ku Band Mobile Satellite Reception

A virtual phase shifter-based phased array is introduced, fabricated, and measured. Compared to the traditional analog phase shifter mechanism, the proposed virtual phase shifter has very precise phase shifting steps (14 bits over 360°) and the constant insertion loss over all phase states. To verify the concepts, a 256 ( ${\bf{16}} \times {\bf{16}}$ )-element planar rectangular grid phased array is built at Ku band for mobile satellite reception. Eleven decibel carrier to noise ratio (C/N) is obtained when the phased array was in its tracking state. System architecture, phased array element design, calibration procedure, and beam tracking methods are also presented in this paper.

대학 학과홈페이지의 평가요소에 대한 상대적 중요도 분석 -부산지역 수험생들의 인식을 중심으로-

본 연구는 대학 홈페이지의 성공적 관리 및 운영이 대학의 브랜딩 효과를 초래한다는 점에 착목하여 기존의 대학 홈페이지 평가요소들의 문제점을 인식하고 새로운 평가모형을 도출한 후 각 단계별 평가요소에 대한 중요도 및 우선순위를 파악하고자 하였다. 특히 본 연구는 의사결정 방법론 중 계층분석과정(AHP)을 활용함으로써 학과 홈페이지 평가요소에 대한 중요도의 객관성을 높이고자 하였다. 분석결과, 29개의 학과 홈페이지 평가요소 중 모바일 서비스, 교과과정의 구성현황 및 교과목의 설명, 학과특성을 나타내는 전문적인 교육내용, 홈페이지 이용안내 및 사이트맵 접근의 용이성, 학과의 차별화된 교육방식 등의 요소는 비교적 중요도가 높게 나타난 반면, 학과특성에 적합한 슬로건, 학과의 차별화된 이미지 및 아이덴티티, 학과 SNS와의 연동, Q&A게시판 제공, 커뮤니티 활발한 운영, FAQ기능의 제공 등의 항목은 상대적 중요도가 낮게 나타났다. 본 연구는 이상의 연구결과를 바탕으로 대학 학과홈페이지의 성공적 관리 및 운영을 위한 기본적 토대를 제시했을 뿐 아니라, 학과홈페이지의 활성화를 위한 몇 가지 시사점을 제시하였다. Form the observation that the successful management and operation of university websites brings about university branding effects, this paper attempts to identify the problems in relation to evaluation elements of university homepages and establish a new evaluation model that allows us to grasp the importance and priority of phased evaluation elements. In particular, we tried to secure the objectivity of the importance of department homepage evaluation elements by using AHP(Analytic Hierarchy Process). Our analysis shows that among 29 evaluation elements of department homepage, mobile service, curriculum, description of department's characteristics, guide to homepage usage/accessibility to site map and differentiated educational method were considered to be relatively important whereas the relative importance of department's slogan, differentiated image and identity, linkage to SNS, Q&A bulletin board, operation of department community, and FAQ was low. Based on the findings from our analysis, we present the basic foundation for successful management and operation of university department homepages along with a few suggestions for vitalizing those hompages.

Beam Control System for Ultrasound Scanning Device

The problems of FPGA based beam control system for ultrasound scanning system is considered. As a result of enhancement of algorithm of linear phased array focusing method for increasing efficiency of phased array elements is proposed. The application of the method for the real ultrasound scanning system is also considered.

Spatial Compounding of Ultrasonic Diagnostic Images for Rotating Linear Probe with Geometric Parameter Error Compensation

In ultrasonic medical imaging, spatial compounding of images is a technique where ultrasonic beam is steered to examine patient tissues in multiple angles. In the conventional ultrasonic diagnostic imaging, the steering of the ultrasonic beam is achieved electronically using the phased array transducer elements. In this paper, a spatial compounding approach is presented where the ultrasonic probe element is rotated mechanically and the beam steering is achieved mechanically. In the spatial compounding, target position is computed using the value of the rotation axis and the transducer array angular position. However, in the process of the rotation mechanism construction and the control system there arises the inevitable uncertainties in these values. These geometric parameter errors result in the target position error, and the consequence is a blurry compounded image. In order to reduce these target position errors, we present a spatial compounding scheme where error correcting transformation matrices are computed and applied to the raw images before spatial compounding to reduce the blurriness in the compounded image. The proposed scheme is illustrated using phantom and live scan images of human knee, and it is shown that the blurriness is effectively reduced.

Optimization of Element Parameters for a New OPFC Ultrasonic Phased Array Transducer

An orthotropic piezoelectric fiber composite (OPFC) element and related OPFC ultrasonic phased array transducer which applied in damage detection of metal structures are investigated by theoretical analysis, numerical simulation and experimental verification methods. Based on electromechanical coupling, the influence of the material characteristics and geometry parameters on actuation performance is studied for the thickness expansion type OPFC elements. In view of lack in the mechanic-electronic parameter design of the existing single PZT element for modern ultrasonic phased array transducer, the related OPFC ultrasonic phased array transducer which used in metal structural damage detection is designed, which have the merits such as low voltage and limit the effects on grating lobe. The focusing acoustic field distribution is analyzed by finite element method together with directivity analysis in metals. The optimal array parameters such as phased array element interval, array element width and number of element are obtained by studying the total displacement changes as various parameters changes at focus point. The preparation of OPFC actuator used in metal structural damage detection is studied. The performance of interdigital OPFC element is also obtained by testing and comparing with the traditional PZT element. The experimental results displayed good agreement with the theoretical predictions.

Design of compact tunable wavelength division multiplexing photonic phased array switches using nano-electromechanical systems on a silicon-on-insulator integration platform

We present the design of novel $$2\times 2$$ and $$4\times 4$$ photonic phased array switch elements with the capability to actively tune wavelength division multiplexing pass-bands. The switch elements use nano-electromechanical systems phase shifters located on the two longitudinal sides of the structures; offering advantages of compact footprint and low-power consumption. The design is verified using the complex finite difference mode three-dimensional full-vectorial solver of the simulation tool FIMMPROP and utilizing custom numerical analysis.

Health Check Experiment of Active Phased Array Antenna Elements on KIZUNA (WINDS) by Two Stations Simultaneous Measurement

Health Check Experiment of Active Phased Array Antenna Elements on KIZUNA (WINDS) by Two Stations Simultaneous Measurement

Research on Improving Lateral Resolution of Ultrasound Phased Array Elements by Using Sparse Matrix

In the phased array imaging system, in order to get better images,the lateral resolution need to be improved and the grating lobes need to be eliminated. Restrainning the width of the main lobe is a way to improve the lateral resolution of the system. This article designed the non-periodic distribution of elements to decrease the width of main lobe of the transducer using sparse matrix methods. In this way, we can improve the lateral resolution, resolve the problem of high-density of elements in phased array element, eliminate the impact of the gate lobe, lowerring the effects of radiation in the neighboring elements, save costs and overcome the difficulty in production of elements.

Ultrasonic Phased Array Industrial Imaging Research with Compressed Sensing

this study presents an eight array ultrasonic signal phased array sparse sampling experiment system based ultrasonic phased array technology and Compressed Sensing (CS). Proposed system considers recovery ultrasonic beam signal received eight phased array elements with sparse samples captured using sub-Nyquist model in CS recovery algorithm. We have the block defect detection test in the system. The test result approximated the actual block defect position. Based on block defect detection test, We compared sparse sampling value using spectrum estimation to Compressed Sensing recovery algorithm imaging, and no focus and focus detection effect, proved the phased array experiment system based on Compressed Sensing .it can greatly improve the detection signal to noise ratio (SNR) and sensitivity. So we verify the phased array focus can improve the detection ability.

Ultrasonic Phased Array Industrial Imaging with Sub-Nyquist Sampling Rate

this paper uses a new type of FRI (Finite Rate of Innovation) sampling pattern based Sub-Nyquist sampling model breaked through Shannon theorem that it can get accurate signal reconstruction based on signal information rate, which requires the sampling frequency lower than two times the max signal frequency. We apply the new model in the ultrasonic phased array industrial imaging. In the experiment, ultrasonic phased array realized dynamic focusing and the high speed scan by ultrasonic array transducer of various array time delays to get flexible controllable synthesis beam composed signals that received by 32 phased array elements . The results indicate that in the model it greatly reduces the signal sampling frequency and improves the signal-to-noise ratio, frequency resolution at the same of the beam focusing and steering flexible.

On the Merit of Asymmetric Phased Array Elements

Phased array antennas with a desired symmetric scan range about broadside usually are designed with array elements that have a corresponding symmetry. However, this appears to be an unnecessary restriction. We 1) show analytically that symmetric scan performance normally is maintained even with asymmetric array elements, and 2) compare conventional symmetric patch elements, which have <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex></formula> - and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane symmetry, with patches which are asymmetric in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$E$</tex></formula> -plane, and with fully non-symmetric patches which have neither <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex> </formula> - nor <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex> </formula> -plane symmetry. The comparison is based on patch designs obtained by numerical optimization, over a 90 degree scan volume and 3:1 bandwidth, using a genetic algorithm. The elements with spoiled symmetry clearly have better scan and/or bandwidth performance. The results support our view that spoiling the symmetry may be a general technique to improve the bandwidth of phased array elements.

A 70–100 GHz Direct-Conversion Transmitter and Receiver Phased Array Chipset Demonstrating 10 Gb/s Wireless Link

A transmitter and receiver phased array chipset is demonstrated in the range between 70 and 100 GHz using a 0.18 µm SiGe BiCMOS process with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$f_{T}/f_{MAX}$</tex> </formula> of 240/270 GHz. Each chip comprises four phased array elements with distributed calibration memory and calibrated direct up- and down-conversion mixer chain. Each receive channel has a conversion gain of 33 dB and noise figure of < 7 dB from 75–95 GHz. Each transmit channel has a flat saturated output power of > 5 dBm between 70 and 100 GHz. Both transmitter and receiver arrays operate from 1.5 V and 2.5 V power supplies and consume 1 W each. Using a die-on-PCB prototype with integrated antennas, a wireless link operating at 10 Gb/s (using 16-QAM) or 8.75 Gb/s (using 32-QAM) is demonstrated at a distance of 1-meter with a carrier frequency of 88 GHz.

Downconverting Module Architectures for High Performance Multipixel Cameras

Multipixel cameras represent an emerging topology for arrays receivers, improving speed and accuracy of both security scanning systems and radioastronomical sky surveys by means of a matrix of phased elements. Difficulties in the generation and proper distribution to each pixel of the local oscillator signal still limit their use to frequency ranges below a few GHz or at least seriously affect the complexity of the implementable cameras. This work presents a full comparison between two possible system architectures, alternatively based on LO frequency multiplication or subharmonic mixing strategies, aiming to overcome the aforesaid limitations: design and performance of two compact test vehicles in MMIC technology, both operating in the Q-band frequency range with ultrabroadband IF section, are reported.

The effect of variation in phased array element performance for Non-Destructive Evaluation (NDE)

This paper reports the results of an investigation into the effects of phased array element performance on ultrasonic beam integrity. This investigation has been performed using an array beam model based on Huygens’ principle to independently investigate the effects of element sensitivity and phase, and non-functioning elements via Monte Carlo simulation. The purpose of this work is to allow a new method of array calibration for Non-Destructive Evaluation (NDE) to be adopted that focuses on probe integrity rather than beam integrity. This approach is better suited to component inspections that utilise Full Matrix Capture (FMC) to record data as the calibration routine is uncoupled from the beams that the array is required to produce. For this approach to be adopted specifications must be placed on element performance that guarantee beam quality without carrying out any beam forming.The principal result of this investigation is that the dominant outcome following variations in array element performance is the introduction of beam artefacts such as main beam broadening, raising of the noise floor of the ultrasonic field, and the enlargement or creation of side lobes. Specifications for practical allowable limits of element sensitivity, element phase, and the number of non-functioning elements have been suggested based on a minimum amplitude difference between beam artefacts and the main beam peak of 8dB. Simulation at a number of centre frequencies has led to a recommendation that the product of transducer bandwidth and maximum phase error should be kept below 0.051 and 0.035 for focused and plane beams respectively. Element sensitivity should be within 50% of mean value of the aperture, and no more than 9% of the elements should be non-functioning.

Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed. In this model, the source boundary conditions of the spheroidal beam equation (SBE) for multi-annular phased elements are studied. Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov—Zabolotskaya—Kuznetsov (KZK) model, respectively. Axial dynamic focusing and the harmonic effects are presented. The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field.

비동기식 레이더의 검출 성능 비교: MIMO 레이더, 위상 배열 레이더, 지향성 MIMO 레이더

기존의 위상 배열 레이더는 인접한 안테나 단일 파형의 위상차를 이용하여 특정 방향으로 신호를 집중시키는 방식이다. 반면, MIMO(Multiple-Input Multiple-Output) 레이더는 다수 파형을 넓게 분포한 안테나를 통해 전송하는 방식이다. 이때, 다수의 파형과 넓게 분포한 안테나로부터 발생한 공간 다이버시티를 높은 SNR (Signal-Noise Ratio) 영역에서는 위상 배열 레이더보다 우수한 타켓 검출 성능을 보인다. 하지만, 낮은 SNR 영역에서는 신호를 집중시켜 어레이 이득을 얻는 위상 배열 레이더가 더 좋은 성능을 나타낸다. 본 논문에서는 MIMO 레이더에 위상 배열 안테나를 결합하여 다이버시티 이득과 어레이 이득을 모두 얻을 수 있는 지향성 MIMO 레이더의 검출 성능을 비교해 본다. 이와 더불어 실제 시스템에서 발생할 수 있는 지향각 오차에 대한 민감도가 성능에 미치는 영향을 분석허여, RF 장비의 수가 제한적이고 타켓 검출 성능이 제한적인 상황에서 각 레이더 성능을 비교하였다. In a traditional phased array radar, closely spaced antenna elements transmit a scaled version of single waveform to maximize the signal energy. On the contrary, a multiple-input multiple-output (MIMO) radar consists of widely separated antennas and transmits an arbitrary waveform from each antenna element. These waveforms and spatial diversity enable superior capabilities compared with phased array radar. At high signal-to-noise ratio (SNR), the detection performance of the MIMO radar is better than the phased array radar due to the diversity gains. However, the phased array radar outperforms the MIMO radar at low SNR, due to the energy maximization. In this paper, we investigate the compromised scheme between the MIMO radar and the phased array radar. Employing the MIMO radar equipped with phased array elements, the compromised scheme achieves both array gain and diversity gain. Also, we compare the performance degradation when the steering direction is incorrect.