Concept of an interlaced phased array for beam switching

Science.gov (United States)

Reddy, C. A.; Janardhanan, K. V.; Mukundan, K. K.; Shenoy, K. S. V.

1990-04-01

A novel concept is described for feeding and phasing a large linear array of N antenna elements using only three or five feed points and phase shifters and still achieving beam switching. The idea consists of drastically reducing the number of input points by interlacing a small number of serially fed subarrays which are suitably phased. This so-called interlaced phased array (IPA) concept was tested using an array of 15 four-element Yagi antennas with a spacing equal to 0.8 wavelengths and found feasible. Some of the distinct advantages of the IPA in comparison with a conventional system of beam switching are reduced power loss, reduced phasing errors, reduced cost, increased reliability resulting from greatly reduced number of phase shifters, and better symmetry of off-zenith beams.

Phased-array radars

Science.gov (United States)

Brookner, E.

1985-02-01

The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

Statistical monitoring of linear antenna arrays

KAUST Repository

Harrou, Fouzi

2016-11-03

The paper concerns the problem of monitoring linear antenna arrays using the generalized likelihood ratio (GLR) test. When an abnormal event (fault) affects an array of antenna elements, the radiation pattern changes and significant deviation from the desired design performance specifications can resulted. In this paper, the detection of faults is addressed from a statistical point of view as a fault detection problem. Specifically, a statistical method rested on the GLR principle is used to detect potential faults in linear arrays. To assess the strength of the GLR-based monitoring scheme, three case studies involving different types of faults were performed. Simulation results clearly shown the effectiveness of the GLR-based fault-detection method to monitor the performance of linear antenna arrays.

Spatial Signature Estimation with an Uncalibrated Uniform Linear Array

Directory of Open Access Journals (Sweden)

Xiang Cao

2015-06-01

Full Text Available In this paper, the problem of spatial signature estimation using a uniform linear array (ULA with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs can only be determined within an unknown rotational angle in this array model. However, the phase ambiguity has no impact on the identification of the spatial signature. Two auto-calibration methods are presented for spatial signature estimation. In our methods, the rotational DOAs and model error parameters are firstly obtained, and the spatial signature is subsequently calculated. The first method extracts two subarrays from the ULA to construct an estimator, and the elements of the array can be used several times in one subarray. The other fully exploits multiple invariances in the interior of the sensor array, and a multidimensional nonlinear problem is formulated. A Gauss–Newton iterative algorithm is applied for solving it. The first method can provide excellent initial inputs for the second one. The effectiveness of the proposed algorithms is demonstrated by several simulation results.

Pattern Nulling of Linear Antenna Arrays Using Backtracking Search Optimization Algorithm

Directory of Open Access Journals (Sweden)

Kerim Guney

2015-01-01

Full Text Available An evolutionary method based on backtracking search optimization algorithm (BSA is proposed for linear antenna array pattern synthesis with prescribed nulls at interference directions. Pattern nulling is obtained by controlling only the amplitude, position, and phase of the antenna array elements. BSA is an innovative metaheuristic technique based on an iterative process. Various numerical examples of linear array patterns with the prescribed single, multiple, and wide nulls are given to illustrate the performance and flexibility of BSA. The results obtained by BSA are compared with the results of the following seventeen algorithms: particle swarm optimization (PSO, genetic algorithm (GA, modified touring ant colony algorithm (MTACO, quadratic programming method (QPM, bacterial foraging algorithm (BFA, bees algorithm (BA, clonal selection algorithm (CLONALG, plant growth simulation algorithm (PGSA, tabu search algorithm (TSA, memetic algorithm (MA, nondominated sorting GA-2 (NSGA-2, multiobjective differential evolution (MODE, decomposition with differential evolution (MOEA/D-DE, comprehensive learning PSO (CLPSO, harmony search algorithm (HSA, seeker optimization algorithm (SOA, and mean variance mapping optimization (MVMO. The simulation results show that the linear antenna array synthesis using BSA provides low side-lobe levels and deep null levels.

Characterization of Kerfless Linear Arrays Based on PZT Thick Film.

Science.gov (United States)

Zawada, Tomasz; Bierregaard, Louise Moller; Ringgaard, Erling; Xu, Ruichao; Guizzetti, Michele; Levassort, Franck; Certon, Dominique

2017-09-01

Multielement transducers enabling novel cost-effective fabrication of imaging arrays for medical applications have been presented earlier. Due to the favorable low lateral coupling of the screen-printed PZT, the elements can be defined by the top electrode pattern only, leading to a kerfless design with low crosstalk between the elements. The thick-film-based linear arrays have proved to be compatible with a commercial ultrasonic scanner and to support linear array beamforming as well as phased array beamforming. The main objective of the presented work is to investigate the performance of the devices at the transducer level by extensive measurements of the test structures. The arrays have been characterized by several different measurement techniques. First, electrical impedance measurements on several elements in air and liquid have been conducted in order to support material parameter identification using the Krimholtz-Leedom-Matthaei model. It has been found that electromechanical coupling is at the level of 35%. The arrays have also been characterized by a pulse-echo system. The measured sensitivity is around -60 dB, and the fractional bandwidth is close to 60%, while the center frequency is about 12 MHz over the whole array. Finally, laser interferometry measurements have been conducted indicating very good displacement level as well as pressure. The in-depth characterization of the array structure has given insight into the performance parameters for the array based on PZT thick film, and the obtained information will be used to optimize the key parameters for the next generation of cost-effective arrays based on piezoelectric thick film.

Directional spectrum of ocean waves from array measurements using phase/time/path difference methods

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.

Wave direction has for the first time been consistently, accurately and unambiguously evaluated from array measurements using the phase/time/path difference (PTPD) methods of Esteva in case of polygonal arrays and Borgman in case of linear arrays...

Statistical monitoring of linear antenna arrays

KAUST Repository

Harrou, Fouzi; Sun, Ying

2016-01-01

The paper concerns the problem of monitoring linear antenna arrays using the generalized likelihood ratio (GLR) test. When an abnormal event (fault) affects an array of antenna elements, the radiation pattern changes and significant deviation from

Determination of Focal Laws for Ultrasonic Phased Array Testing of Dissimilar Metal Welds

International Nuclear Information System (INIS)

Jing, Ye; Kim, Hak Joon; Song, Sung Jin; Song, Myung Ho; Kang, Suk Chull; Kang, Sung Sik; Kim, Kyung Cho

2008-01-01

Inspection of dissimilar metal welds using phased array ultrasound is not easy at all, because crystalline structure of dissimilar metal welds cause deviation and splitting of the ultrasonic beams. Thus, in order to have focusing and/or steering phased array beams in dissimilar metal welds, proper time delays should be determined by ray tracing. In this paper, we proposed an effective approach to solve this difficult problem. Specifically, we modify the Oglivy's model parameters to describe the crystalline structure of real dissimilar metal welds in a fabricated specimen. And then, we calculate the proper time delay and incident angle of linear phased array transducer in the anisotropic and inhomogeneous material for focusing and/or steering phased array ultrasonic beams on the desired position

Improvement of detection of stress corrosion cracks with ultrasonic phased array probes

International Nuclear Information System (INIS)

Wustenberg, H.; Mohrle, W.; Wegner, W.; Schenk, G.; Erhard, A.

1986-01-01

Probes with linear arrays can be used for the detection of stress corrosion cracks especially if the variability of the sound field is used to change the skewing angle of angle beam probes. The phased array concept can be used to produce a variable skewing angle or a variable angle of incidence depending on the orientation of the linear array on the wedge. This helps to adapt the direction of the ultrasonic beam to probable crack orientations. It has been demonstrated with artificial reflectors as well as with corrosion cracks, that the detection of misoriented cracks can be improved by this approach. The experiences gained during the investigations are encouraging the application of phased array probes for stress corrosion phenomena close to the heat effected zone of welds. Probes with variable skewing angles may find some interesting applications on welds in tubular structures e.g., at off shore constructions and on some difficult geometries within the primary circuit of nuclear power plants

Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry

Science.gov (United States)

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Khodadoust, Saeid

2015-08-01

A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r2 = 0.998) in the range of 3.0-85.0 μg L-1 with a detection limit of 0.7 μg L-1 for preconcentration of 25.0 mL of the sample and the relative standard deviation (n = 6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments.

Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry.

Science.gov (United States)

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Khodadoust, Saeid

2015-08-05

A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r(2)=0.998) in the range of 3.0-85.0 μg L(-1) with a detection limit of 0.7 μg L(-1) for preconcentration of 25.0 mL of the sample and the relative standard deviation (n=6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

New applications using phased array techniques

International Nuclear Information System (INIS)

Erhard, A.; Schenk, G.; Hauser, Th.; Voelz, U.

2001-01-01

In general, the application of phased array techniques used to be limited to heavy components with large wall thicknesses, such as those in the nuclear power industry. With the improvement of the phased array equipment, including phased array search units, other application areas are now accessible for the phased array inspection technique, e.g. the inspection of turbine blade roots, weld inspection with a wall thickness ranging from 12 to 40 mm, inspection of aircraft components, inspection of spot welds and the inspection of concrete building components. The objective for the use of phased array techniques has not significantly changed since their first application, e.g. instant adjustment of the sound beam to the geometry of the test object by steering incidence angle, skew angle and/or sound field focusing. Because some new phased array technique applications are still in the experimental (laboratory) stage, this article will focus on some examples for practical, real-weld applications

Application of optical processing to adaptive phased array radar

Science.gov (United States)

Carroll, C. W.; Vijaya Kumar, B. V. K.

1988-01-01

The results of the investigation of the applicability of optical processing to Adaptive Phased Array Radar (APAR) data processing will be summarized. Subjects that are covered include: (1) new iterative Fourier transform based technique to determine the array antenna weight vector such that the resulting antenna pattern has nulls at desired locations; (2) obtaining the solution of the optimal Wiener weight vector by both iterative and direct methods on two laboratory Optical Linear Algebra Processing (OLAP) systems; and (3) an investigation of the effects of errors present in OLAP systems on the solution vectors.

MEMS based monolithic Phased array using 3-bit Switched-line Phase Shifter

Directory of Open Access Journals (Sweden)

A. Karmakr

2017-10-01

Full Text Available This article details the design of an electronically scanning phased array antenna with proposed fabrication process steps. Structure is based upon RF micro-electromechanical system (MEMS technology. Capacitive type shunt switches have been implemented here to cater high frequency operation. The architecture, which is deigned at 30 GHz, consists of 3-bit (11.25º, 22.5º and 45º integrated Switched-line phase shifter and a linearly polarized microstrip patch antenna. Detailed design tricks of the Ka-band phase shifter is outlined here. The whole design is targeted for future monolithic integration. So, the substrate of choice is High Resistive Silicon (ρ > 8kΩ-cm, tan δ =0.01 and ϵr =11.8. The overall circuit occupies an cross-sectional area of 20 × 5 mm2. The simulated results show that the phase shifter can provide nearly 11.25º/22.5º/45º phase shifts and their combinations at the expense of 1dB average insertion loss at 30 GHz for eight combinations. Practical fabrication process flow using surface micromachining is proposed here. Critical dimensions of the phased array structure is governed by the deign rules of the standard CMOS/MEMS foundry.

Synthesis of Phase-Only Reconfigurable Linear Arrays Using Multiobjective Invasive Weed Optimization Based on Decomposition

Directory of Open Access Journals (Sweden)

Yan Liu

2014-01-01

Full Text Available Synthesis of phase-only reconfigurable array aims at finding a common amplitude distribution and different phase distributions for the array to form different patterns. In this paper, the synthesis problem is formulated as a multiobjective optimization problem and solved by a new proposed algorithm MOEA/D-IWO. First, novel strategies are introduced in invasive weed optimization (IWO to make original IWO fit for solving multiobjective optimization problems; then, the modified IWO is integrated into the framework of the recently well proved competitive multiobjective optimization algorithm MOEA/D to form a new competitive MOEA/D-IWO algorithm. At last, two sets of experiments are carried out to illustrate the effectiveness of MOEA/D-IWO. In addition, MOEA/D-IWO is compared with MOEA/D-DE, a new version of MOEA/D. The comparing results show the superiority of MOEA/D-IWO and indicate its potential for solving the antenna array synthesis problems.

Development of phased-array ultrasonic testing probe

International Nuclear Information System (INIS)

Kawanami, Seiichi; Kurokawa, Masaaki; Taniguchi, Masaru; Tada, Yoshihisa

2001-01-01

Phased-array ultrasonic testing was developed for nondestructive evaluation of power plants. Phased-array UT scans and focuses an ultrasonic beam to inspect areas difficult to inspect by conventional UT. We developed a highly sensitive piezoelectric composite, and designed optimized phased-array UT probes. We are applying our phased-array UT to different areas of power plants. (author)

Dynamic focusing of phased arrays for nondestructive testing: characterization and application

International Nuclear Information System (INIS)

Lamarre, A.; Mainguy, F.

1999-01-01

Recent developments in Phased Array hardware developed by R/D TECH for nondestructive testing now allow dynamic focusing on reception. This new option, borrowed from medical technology, enables a programmable, real-time array response on reception by modifying the delay line, the gain, and the activation of each element as a function of time. This technology is presented as a new powerful tool, which can extend the depth-of-field, reduce the beam spread and increase the overall signal-to-noise ratio. Implementation of dynamic focusing in Phased Array systems will present many advantages such as an increase of the Pulse Rate Frequency (PRF). The technology implies a lot of significant possibilities, but also an extensive beam characterization. Some results are presented to quantify the advantages and drawbacks of the technique in comparison with standard phased array zone focusing and conventional UT. Results are clearly demonstrating the effect of dynamic focusing on the depth-of-field, the beam spread, the signal-to-noise ratio, and the acquisition rate, both with linear and annular arrays. Therefore this technique is suitable for applications where long soundpaths and small beam divergence are required as boresonic, billet, and blade root inspections. (author)

SAFT-assisted sound beam focusing using phased arrays (PA-SAFT) for non-destructive evaluation

Science.gov (United States)

Nanekar, Paritosh; Kumar, Anish; Jayakumar, T.

2015-04-01

Focusing of sound has always been a subject of interest in ultrasonic non-destructive evaluation. An integrated approach to sound beam focusing using phased array and synthetic aperture focusing technique (PA-SAFT) has been developed in the authors' laboratory. The approach involves SAFT processing on ultrasonic B-scan image collected by a linear array transducer using a divergent sound beam. The objective is to achieve sound beam focusing using fewer elements than the ones required using conventional phased array. The effectiveness of the approach is demonstrated on aluminium blocks with artificial flaws and steel plate samples with embedded volumetric weld flaws, such as slag and clustered porosities. The results obtained by the PA-SAFT approach are found to be comparable to those obtained by conventional phased array and full matrix capture - total focusing method approaches.

Sonography of the chest using linear-array versus sector transducers: Correlation with auscultation, chest radiography, and computed tomography.

Science.gov (United States)

Tasci, Ozlem; Hatipoglu, Osman Nuri; Cagli, Bekir; Ermis, Veli

2016-07-08

The primary purpose of our study was to compare the efficacies of two sonographic (US) probes, a high-frequency linear-array probe and a lower-frequency phased-array sector probe in the diagnosis of basic thoracic pathologies. The secondary purpose was to compare the diagnostic performance of thoracic US with auscultation and chest radiography (CXR) using thoracic CT as a gold standard. In total, 55 consecutive patients scheduled for thoracic CT were enrolled in this prospective study. Four pathologic entities were evaluated: pneumothorax, pleural effusion, consolidation, and interstitial syndrome. A portable US scanner was used with a 5-10-MHz linear-array probe and a 1-5-MHz phased-array sector probe. The first probe used was chosen randomly. US, CXR, and auscultation results were compared with the CT results. The linear-array probe had the highest performance in the identification of pneumothorax (83% sensitivity, 100% specificity, and 99% diagnostic accuracy) and pleural effusion (100% sensitivity, 97% specificity, and 98% diagnostic accuracy); the sector probe had the highest performance in the identification of consolidation (89% sensitivity, 100% specificity, and 95% diagnostic accuracy) and interstitial syndrome (94% sensitivity, 93% specificity, and 94% diagnostic accuracy). For all pathologies, the performance of US was superior to those of CXR and auscultation. The linear probe is superior to the sector probe for identifying pleural pathologies, whereas the sector probe is superior to the linear probe for identifying parenchymal pathologies. Thoracic US has better diagnostic performance than CXR and auscultation for the diagnosis of common pathologic conditions of the chest. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:383-389, 2016. © 2016 Wiley Periodicals, Inc.

Assessment of the Roche Linear Array HPV Genotyping Test within the VALGENT framework.

Science.gov (United States)

Xu, Lan; Oštrbenk, Anja; Poljak, Mario; Arbyn, Marc

2018-01-01

Cervical cancer screening programs are switching from cytology-based screening to high-risk (hr) HPV testing. Only clinically validated tests should be used in clinical practice. To assess the clinical performance of the Roche Linear Array HPV genotyping test (Linear Array) within the VALGENT-3 framework. The VALGENT framework is designed for comprehensive comparison and clinical validation of HPV tests that have limited to extended genotyping capacity. The Linear Array enables type-specific detection of 37 HPV types. For the purpose of this study, Linear Array results were designated as positive only if one of the 13 hrHPV types also included in the Hybrid Capture 2 (HC2) was detected. The VALGENT-3 framework comprised 1600 samples obtained from Slovenian women (1300 sequential cases from routine cervical cancer screening enriched with 300 cytological abnormal samples). Sensitivity for cervical intraepithelial neoplasia of grade 2 or worse (CIN2+) (n=127) and specificity for Linear Array and for HC2 and non-inferiority of Linear Array relative to HC2 was checked. In addition, the prevalence of separate hrHPV types in the screening population, as well as the concordance for presence of HPV16, HPV18 and other hrHPV types between Linear Array and the Abbott RealTime High Risk HPV test (RealTime) were assessed. The clinical sensitivity and specificity for CIN2+ of the Linear Array in the total study population was 97.6% (95% CI, 93.3-99.5%) and 91.7% (95% CI, 90.0-93.2%), respectively. The relative sensitivity and specificity of Linear Array vs HC2 was 1.02 [95% CI, 0.98-1.05, (pLinear Array in the screening population was 10.5% (95% CI, 8.9-12.3%) with HPV16 and HPV18 detected in 2.3% and 0.9% of the samples, respectively. Excellent agreement for presence or absence of HPV16, HPV18 and other hrHPV between Linear Array and RealTime was observed. Linear Array showed similar sensitivity with higher specificity to detect CIN2+ compared to HC2. Detection of 13 hrHPV types

Linear-array systems for aerospace NDE

International Nuclear Information System (INIS)

Smith, Robert A.; Willsher, Stephen J.; Bending, Jamie M.

1999-01-01

Rapid large-area inspection of composite structures for impact damage and multi-layered aluminum skins for corrosion has been a recognized priority for several years in both military and civil aerospace applications. Approaches to this requirement have followed two clearly different routes: the development of novel large-area inspection systems, and the enhancement of current ultrasonic or eddy-current methods to reduce inspection times. Ultrasonic inspection is possible with standard flaw detection equipment but the addition of a linear ultrasonic array could reduce inspection times considerably. In order to investigate their potential, 9-element and 17-element linear ultrasonic arrays for composites, and 64-element arrays for aluminum skins, have been developed to DERA specifications for use with the ANDSCAN area scanning system. A 5 m 2 composite wing surface has been scanned with a scan resolution of approximately 3 mm in 6 hours. With subsequent software and hardware improvements all four composite wing surfaces (top/bottom, left/right) of a military fighter aircraft can potentially be inspected in less than a day. Array technology has been very widely used in the medical ultrasound field although rarely above 10 MHz, whereas lap-joint inspection requires a pulse center-frequency of 12 to 20 MHz in order to resolve the separate interfaces in the lap joint. A 128 mm-long multi-element array of 5 mmx2 mm ultrasonic elements for use with the ANDSCAN scanning software was produced to a DERA specification by an NDT manufacturer with experience in the medical imaging field. This paper analyses the performance of the transducers that have been produced and evaluates their use in scanning systems of different configurations

Pulse-echo phased array ultrasonic inspection of pultruded rod stitched efficient unitized structure (PRSEUS)

International Nuclear Information System (INIS)

Johnston, P. H.

2011-01-01

A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading.

Improvement of resolution in full-view linear-array photoacoustic computed tomography using a novel adaptive weighting method

Science.gov (United States)

Omidi, Parsa; Diop, Mamadou; Carson, Jeffrey; Nasiriavanaki, Mohammadreza

2017-03-01

Linear-array-based photoacoustic computed tomography is a popular methodology for deep and high resolution imaging. However, issues such as phase aberration, side-lobe effects, and propagation limitations deteriorate the resolution. The effect of phase aberration due to acoustic attenuation and constant assumption of the speed of sound (SoS) can be reduced by applying an adaptive weighting method such as the coherence factor (CF). Utilizing an adaptive beamforming algorithm such as the minimum variance (MV) can improve the resolution at the focal point by eliminating the side-lobes. Moreover, invisibility of directional objects emitting parallel to the detection plane, such as vessels and other absorbing structures stretched in the direction perpendicular to the detection plane can degrade resolution. In this study, we propose a full-view array level weighting algorithm in which different weighs are assigned to different positions of the linear array based on an orientation algorithm which uses the histogram of oriented gradient (HOG). Simulation results obtained from a synthetic phantom show the superior performance of the proposed method over the existing reconstruction methods.

Non-destructive visualization of linear explosive-induced Pyroshock using phase arrayed laser-induced shock in a space launcher composite

International Nuclear Information System (INIS)

Jang, Jae Kyeong; Lee, Jung Ryul

2015-01-01

Separation mechanism of Space launch vehicles are used in various separation systems and pyrotechnic devices. The operation of these pyrotechnic devices generates Pyroshock that can cause failures in electronic components. The prediction of high frequency structural response, especially the shock response spectrum (SRS), is important. This paper presents a non-destructive visualization and simulation of linear explosive-induced Pyroshock using phase arrayed Laser-induced shock. The proposed method includes a laser shock test based on laser beam and filtering zone conditioning to predict the SRS of Pyroshock. A ballistic test based on linear explosive and non-contact Laser Doppler Vibrometers and a nondestructive Laser shock measurement using laser excitation and several PZT sensors, are performed using a carbon composite sandwich panel. The similarity of the SRS of the conditioned laser shock to that of the real explosive Pyroshock is evaluated with the Mean Acceleration Difference. The average of MADs over the two training points was 33.64%. And, MAD at verification point was improved to 31.99%. After that, experimentally found optimal conditions are applied to any arbitrary points in laser scanning area. Finally, it is shown that linear explosive-induced real Pyroshock wave propagation can be visualized with high similarity based on the proposed laser technology. (paper)

Antennas for Frequency Reconfigurable Phased Arrays

NARCIS (Netherlands)

Haider, S.N.

2015-01-01

Sensors such as phased array radars play a crucial role in public safety. They are unavoidable for surveillance, threat identification and post-disaster management. However, different scenarios impose immensely diverse requirements for these systems. Phased array systems occupy a large space. In

Detecting failed elements on phased array ultrasound transducers using the Edinburgh Pipe Phantom

Science.gov (United States)

Inglis, Scott; Pye, Stephen D

2016-01-01

Aims Imaging faults with ultrasound transducers are common. Failed elements on linear and curvilinear array transducers can usually be detected with a simple image uniformity or ‘paperclip’ test. However, this method is less effective for phased array transducers, commonly used in cardiac imaging. The aim of this study was to assess whether the presence of failed elements could be detected through measurement of the resolution integral (R) using the Edinburgh Pipe Phantom. Methods A 128-element paediatric phased array transducer was studied. Failed elements were simulated using layered polyvinyl chloride (PVC) tape as an attenuator and measurements of resolution integral were carried out for several widths of attenuator. Results All widths of attenuator greater than 0.5 mm resulted in a significant reduction in resolution integral and low contrast penetration measurements compared to baseline (p tests to detect failed elements on phased array transducers. Particularly encouraging is the result for low contrast penetration as this is a quick and simple measurement to make and can be performed with many different test objects, thus enabling ‘in-the-field’ checks. PMID:27482276

Linearly tapered slot antenna circular array for mobile communications

Science.gov (United States)

Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

1993-01-01

The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

Applications of the phased array technique

International Nuclear Information System (INIS)

Erhard, A.; Schenk, G.; Hauser, Th.; Voelz, U.

1999-01-01

The application of the phased array technique was limited to heavy and thick wall components as present in the nuclear industry. With the improvement of the equipment and probes other application areas are now open for the phased array technique, e.g. the inspection of the turbine blade root, weld inspection in a wall thickness range between 12 and 40 mm, inspection of aircraft components, inspection of spot welds or inspection of concretes. The aim of the use of phased array techniques has not been changed related to the first applications, i.e. the adaptation of the sound beam to the geometry by steering the angel of incidence or the skewing angle as well as the focussing of sound fields. Due to the fact, that the new applications of the phased array techniques in some cases don't leave the laboratories for the time being, the examples of this contribution will focus applications with practical background. (orig.)

Determination of wave direction from linear and polygonal arrays

Digital Repository Service at National Institute of Oceanography (India)

Fernandes, A.A; Gouveia, A; Nagarajan, R.

documentation of Borgman (1974) in case of linear arrays; and the second issue being the failure of Esteva (1976, 1977) to correctly determine wave directions over the design range 25 to 7 sec of his polygonal array. This paper presents requisite documentation...

Linear complexity for multidimensional arrays - a numerical invariant

DEFF Research Database (Denmark)

Gomez-Perez, Domingo; Høholdt, Tom; Moreno, Oscar

2015-01-01

Linear complexity is a measure of how complex a one dimensional sequence can be. In this paper we extend the concept of linear complexity to multiple dimensions and present a definition that is invariant under well-orderings of the arrays. As a result we find that our new definition for the proce...

Intracavitary ultrasound phased arrays for thermal therapies

Science.gov (United States)

Hutchinson, Erin

Currently, the success of hyperthermia and thermal surgery treatments is limited by the technology used in the design and fabrication of clinical heating devices and the completeness of the thermometry systems used for guidance. For both hyperthermia and thermal surgery, electrically focused ultrasound generated by phased arrays provides a means of controlling localized energy deposition in body tissues. Intracavitary applicators can be used to bring the energy source close to a target volume, such as the prostate, thereby minimizing normal tissue damage. The work performed in this study was aimed at improving noninvasive prostate thermal therapies and utilized three research approaches: (1) Acoustic, thermal and optimization simulations, (2) Design and fabrication of multiple phased arrays, (3) Ex vivo and in vivo experimental testing of the heating capabilities of the phased arrays. As part of this study, a novel aperiodic phased array design was developed which resulted in a 30- 45% reduction in grating lobe levels when compared to conventional phased arrays. Measured acoustic fields generated by the constructed aperiodic arrays agreed closely with the fields predicted by the theoretical simulations and covered anatomically appropriate ranges. The power capabilities of these arrays were demonstrated to be sufficient for the purposes of hyperthermia and thermal surgery. The advantage of using phased arrays in place of fixed focus transducers was shown by demonstrating the ability of electronic scanning to increase the size of the necrosed tissue volume while providing a more uniform thermal dose, which can ultimately reduce patient treatment times. A theoretical study on the feasibility of MRI (magnetic resonance imaging) thermometry for noninvasive temperature feedback control was investigated as a means to improve transient and steady state temperature distributions achieved in hyperthermia treatments. MRI guided ex vivo and in vivo experiments demonstrated

Quantum criticality of geometric phase in coupled optical cavity arrays under linear quench

OpenAIRE

Sarkar, Sujit

2013-01-01

The atoms trapped in microcavities and interacting through the exchange of virtual photons can be modeled as an anisotropic Heisenberg spin-1/2 lattice. We study the dynamics of the geometric phase of this system under the linear quenching process of laser field detuning which shows the XX criticality of the geometric phase in presence of single Rabi frequency oscillation. We also study the quantum criticality for different quenching rate in the presence of single or two Rabi frequencies osci...

Compression dynamics of quasi-spherical wire arrays with different linear mass profiles

International Nuclear Information System (INIS)

Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Oleinik, G. M.; Ol’khovskaya, O. G.

2016-01-01

Results of experimental studies of the implosion of quasi-spherical wire (or metalized fiber) arrays are presented. The goal of the experiments was to achieve synchronous three-dimensional compression of the plasma produced in different regions of a quasi-spherical array into its geometrical center. To search for optimal synchronization conditions, quasi-spherical arrays with different initial profiles of the linear mass were used. The following dependences of the linear mass on the poloidal angle were used: m_l(θ) ∝ sin"–"1θ and m_l(θ) ∝ sin"–"2θ. The compression dynamics of such arrays was compared with that of quasi-spherical arrays without linear mass profiling, m_l(θ) = const. To verify the experimental data, the spatiotemporal dynamics of plasma compression in quasi-spherical arrays was studied using various diagnostics. The experiments on three-dimensional implosion of quasi-spherical arrays made it possible to study how the frozen-in magnetic field of the discharge current penetrates into the array. By measuring the magnetic field in the plasma of a quasi-spherical array, information is obtained on the processes of plasma production and formation of plasma flows from the wire/fiber regions with and without an additionally deposited mass. It is found that penetration of the magnetic flux depends on the initial linear mass profile m_l(θ) of the quasi-spherical array. From space-resolved spectral measurements and frame imaging of plasma X-ray emission, information is obtained on the dimensions and shape of the X-ray source formed during the implosion of a quasi-spherical array. The intensity of this source is estimated and compared with that of the Z-pinch formed during the implosion of a cylindrical array.

Very high frequency (beyond 100 MHz) PZT kerfless linear arrays.

Science.gov (United States)

Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K Kirk

2009-10-01

This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-microm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-microm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss).

HPV genotype-specific concordance between EuroArray HPV, Anyplex II HPV28 and Linear Array HPV Genotyping test in Australian cervical samples

Directory of Open Access Journals (Sweden)

Alyssa M. Cornall

2017-12-01

Full Text Available Purpose: To compare human papillomavirus genotype-specific performance of two genotyping assays, Anyplex II HPV28 (Seegene and EuroArray HPV (EuroImmun, with Linear Array HPV (Roche. Methods: DNA extracted from clinican-collected cervical brush specimens in PreservCyt medium (Hologic, from 403 women undergoing management for detected cytological abnormalities, was tested on the three assays. Genotype-specific agreement were assessed by Cohen's kappa statistic and Fisher's z-test of significance between proportions. Results: Agreement between Linear Array and the other 2 assays was substantial to almost perfect (κ = 0.60 − 1.00 for most genotypes, and was almost perfect (κ = 0.81 – 0.98 for almost all high-risk genotypes. Linear Array overall detected most genotypes more frequently, however this was only statistically significant for HPV51 (EuroArray; p = 0.0497, HPV52 (Anyplex II; p = 0.039 and HPV61 (Anyplex II; p=0.047. EuroArray detected signficantly more HPV26 (p = 0.002 and Anyplex II detected more HPV42 (p = 0.035 than Linear Array. Each assay performed differently for HPV68 detection: EuroArray and LA were in moderate to substantial agreement with Anyplex II (κ = 0.46 and 0.62, respectively, but were in poor disagreement with each other (κ = −0.01. Conclusions: EuroArray and Anyplex II had similar sensitivity to Linear Array for most high-risk genotypes, with slightly lower sensitivity for HPV 51 or 52. Keywords: Human papillomavirus, Genotyping, Linear Array, Anyplex II, EuroArray, Cervix

Brazilian Decimetric Array (BDA) project - Phase II

Science.gov (United States)

Faria, C.; Stephany, S.; Sawant, H. S.; Cecatto, J. R.; Fernandes, F. C. R.

2010-02-01

The configuration of the second phase of the Brazilian Decimetric Array (BDA), installed at Cachoeira Paulista, Brazil (Longitude 45° 0‧ 20″ W and Latitude 22° 41‧ 19″ S), is a T-shaped array where 21 antennas are being added to existing 5 antennas of the first phase. In the third phase, in each arm of the T array, four more antennas will be added and baselines will be increased to 2.5 × 1.25 km in east-west and south directions, respectively. The antennas will be equally spaced at the distances of 250 meters from the central antenna of the T-array. Also, the frequency range will be increased to 1.2-1.7, 2.8 and 5.6 GHz. The Second phase of the BDA should be operational by the middle of 2010 and will operate in the frequency range of (1.2-1.7) GHz for solar and non solar observations. Here, we present the characteristics of the second phase of the BDA project, details of the array configuration, the u-v coverage, the synthesized beam obtained for the proposed configuration.

Phased Array Ultrasonic Inspection of Titanium Forgings

International Nuclear Information System (INIS)

Howard, P.; Klaassen, R.; Kurkcu, N.; Barshinger, J.; Chalek, C.; Nieters, E.; Sun, Zongqi; Fromont, F. de

2007-01-01

Aerospace forging inspections typically use multiple, subsurface-focused sound beams in combination with digital C-scan image acquisition and display. Traditionally, forging inspections have been implemented using multiple single element, fixed focused transducers. Recent advances in phased array technology have made it possible to perform an equivalent inspection using a single phased array transducer. General Electric has developed a system to perform titanium forging inspection based on medical phased array technology and advanced image processing techniques. The components of that system and system performance for titanium inspection will be discussed

Phased antenna arrays for fast wave power generation

International Nuclear Information System (INIS)

Bosia, G.; Jacquinot, J.

1991-01-01

A method for the generation of travelling waves in the Ion Cyclotron frequency range in JET is presented. The success of the method relies on the control of the array toroidal current, which in turn, is obtained by a coordinated vectorial control of the array power sources and tuning networks. This method has general application to present and future ICRF arrays. For uninterrupted, periodically fed and resonant toroidal arrays, phased operation requires only conventional tuning devices. For localised arrays, phased operation is inefficient at low plasma coupling. This inefficiency can be however removed with the addition of external coupling structures either at the antenna or at the generator ends. The performances of JET A1 antennae in phased operation is presented. The design philosophy for the JET A2 phased arrays is also discussed. These methods are applicable and extensible to Next Step Devices design

FY16 Status of Immersion Phased Array Ultrasonic Probe Development and Performance Demonstration Results for Under Sodium Viewing

International Nuclear Information System (INIS)

Diaz, Aaron A.; Chamberlin, Clyde E.; Edwards, Matthew K.; Hagge, Tobias J.; Hughes, Michael S.; Larche, Michael R.; Mathews, Royce A.; Neill, Kevin J.; Prowant, Matthew S.

2016-01-01

This section of the Joint summary technical letter report (TLR) describes work conducted at the Pacific Northwest National Laboratory (PNNL) during FY 2016 (FY16) on the under-sodium viewing (USV) PNNL project 58745, work package AT-16PN230102. This section of the TLR satisfies PNNL's M3AT-16PN2301025 milestone and is focused on summarizing the design, development, and evaluation of two different phased-array ultrasonic testing (PA-UT) probe designs - a two-dimensional (2D) matrix phased-array probe, and two one-dimensional (1D) linear array probes, referred to as serial number 4 (SN4) engineering test units (ETUs). The 2D probe is a pulse-echo (PE), 32x2, 64-element matrix phased-array ETU. The 1D probes are 32x1 element linear array ETUs. This TLR also provides the results from a performance demonstration (PD) of in-sodium target detection trials at 260°C using both probe designs. This effort continues the iterative evolution supporting the longer term goal of producing and demonstrating a pre-manufacturing prototype ultrasonic probe that possesses the fundamental performance characteristics necessary to enable the development of a high-temperature sodium-cooled fast reactor (SFR) inspection system for in-sodium detection and imaging.

FY16 Status of Immersion Phased Array Ultrasonic Probe Development and Performance Demonstration Results for Under Sodium Viewing

Energy Technology Data Exchange (ETDEWEB)

Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chamberlin, Clyde E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Edwards, Matthew K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hagge, Tobias J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hughes, Michael S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Larche, Michael R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mathews, Royce A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Neill, Kevin J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prowant, Matthew S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-08-31

This section of the Joint summary technical letter report (TLR) describes work conducted at the Pacific Northwest National Laboratory (PNNL) during FY 2016 (FY16) on the under-sodium viewing (USV) PNNL project 58745, work package AT-16PN230102. This section of the TLR satisfies PNNL’s M3AT-16PN2301025 milestone and is focused on summarizing the design, development, and evaluation of two different phased-array ultrasonic testing (PA-UT) probe designs—a two-dimensional (2D) matrix phased-array probe, and two one-dimensional (1D) linear array probes, referred to as serial number 4 (SN4) engineering test units (ETUs). The 2D probe is a pulse-echo (PE), 32×2, 64-element matrix phased-array ETU. The 1D probes are 32×1 element linear array ETUs. This TLR also provides the results from a performance demonstration (PD) of in-sodium target detection trials at 260°C using both probe designs. This effort continues the iterative evolution supporting the longer term goal of producing and demonstrating a pre-manufacturing prototype ultrasonic probe that possesses the fundamental performance characteristics necessary to enable the development of a high-temperature sodium-cooled fast reactor (SFR) inspection system for in-sodium detection and imaging.

Manual phased arrays for weld inspections using North American codes

International Nuclear Information System (INIS)

Moles, Michael

2008-01-01

Phased arrays are primarily a method of generating and receiving ultrasound, not a new technology. In addition, the physics of ultrasound generated by phased arrays is identical to that from conventional monocrystals. Not surprisingly, all the major North American (and some European) codes accept phased arrays, either explicitly or implicitly. However, the technique and procedures needs to be proven, typically by a Performance Demonstration. The ASME (AmeicanSociety for Mechanical Engineers) Section V and API RP2X explicitly accept phased arrays. Three ASME code cases have been written specifically fo manual phased array: Code Cases 2541. 2557 and 2558. Over and above the general requirements of Article 4, these Code Cases require full waveform calibration. This is echoed in ASTM E-2491, a Standard Guide for setting up phased arrays. In addition. details such as focusing and reporting are addressed. The American Petroleum Institute QUTE procedure did not need any modifications to be compatible with manual phased arrays. The American Welding Society (AWS) Structural Welding Code D1.1 implicitly accepts phased arrays. New technologies such as phased arrays can be proven using Annex K. Nonetheless, a manual phased array unit using the standard AWS probe and displaying 45, 60 and 70degrees waveforms would be acceptable for D1.1 a s is . Overall, most major North American codes accept phased arrays, however, the technique and procedures must be proven, often using a Performance Demonstration. (author)

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

Science.gov (United States)

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

Ferrite LTCC based phased array antennas

KAUST Repository

Ghaffar, Farhan A.

2016-11-02

Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

Science.gov (United States)

Host, Nick; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix

2013-01-01

Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex, heavy and most importantly costly. This presentation paper presents a concept which overcomes these detrimental attributes by eliminating all of the phase array backend (including phase shifters). Instead, a wave velocity reconfigurable transmission line is used in a series fed array arrangement to allow phase shifting with one small (100mil) mechanical motion. Different configurations of the reconfigurable wave velocity transmission line are discussed and simulated and experimental results are presented.

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

Science.gov (United States)

Yu, Li-Li; Shou, Wen-De; Hui, Chun

2012-02-01

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.

HPV genotype-specific concordance between EuroArray HPV, Anyplex II HPV28 and Linear Array HPV Genotyping test in Australian cervical samples.

Science.gov (United States)

Cornall, Alyssa M; Poljak, Marin; Garland, Suzanne M; Phillips, Samuel; Machalek, Dorothy A; Tan, Jeffrey H; Quinn, Michael A; Tabrizi, Sepehr N

2017-12-01

To compare human papillomavirus genotype-specific performance of two genotyping assays, Anyplex II HPV28 (Seegene) and EuroArray HPV (EuroImmun), with Linear Array HPV (Roche). DNA extracted from clinican-collected cervical brush specimens in PreservCyt medium (Hologic), from 403 women undergoing management for detected cytological abnormalities, was tested on the three assays. Genotype-specific agreement were assessed by Cohen's kappa statistic and Fisher's z-test of significance between proportions. Agreement between Linear Array and the other 2 assays was substantial to almost perfect (κ = 0.60 - 1.00) for most genotypes, and was almost perfect (κ = 0.81 - 0.98) for almost all high-risk genotypes. Linear Array overall detected most genotypes more frequently, however this was only statistically significant for HPV51 (EuroArray; p = 0.0497), HPV52 (Anyplex II; p = 0.039) and HPV61 (Anyplex II; p=0.047). EuroArray detected signficantly more HPV26 (p = 0.002) and Anyplex II detected more HPV42 (p = 0.035) than Linear Array. Each assay performed differently for HPV68 detection: EuroArray and LA were in moderate to substantial agreement with Anyplex II (κ = 0.46 and 0.62, respectively), but were in poor disagreement with each other (κ = -0.01). EuroArray and Anyplex II had similar sensitivity to Linear Array for most high-risk genotypes, with slightly lower sensitivity for HPV 51 or 52. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Application of ultrasonic phased array technique for inspection of stud bolts in nuclear reactor vessel

International Nuclear Information System (INIS)

Choi, Sang Woo; Lee, Joon Ho; Park, Min Su; Cho, Youn Ho; Park, Moon Ho

2004-01-01

The stud bolt is one of crucial parts for safety of reactor vessels in nuclear power plants. Cracks initiation and propagation were reported in stud bolts using closure of reactor vessel and head. Stud bolts are inspected by ultrasonic technique during overhaul periodically for the prevention of stud bolt failure and radioactive leakage from nuclear reactor. In conventional ultrasonic testing for inspection of stud bolts, crack was detected by using shadow effect. It take too much time to inspect stud bolt by using conventional ultrasonic technique. In addition, there were numerous spurious signal reflected from every thread. In this study, the advanced ultrasonic phased array technique was introduced for inspect stud bolts. The phased array technique provide fast inspection and high detectability of defects. There are sector scanning and linear scanning method in phased array technique, and these scanning methods were applied to inspect stud bolt and detectability was investigated.

On the (Frequency) Modulation of Coupled Oscillator Arrays in Phased Array Beam Control

Science.gov (United States)

Pogorzelski, R.; Acorn, J.; Zawadzki, M.

2000-01-01

It has been shown that arrays of voltage controlled oscillators coupled to nearest neighbors can be used to produce useful aperture phase distributions for phased array antennas. However, placing information of the transmitted signal requires that the oscillations be modulated.

Multispectral linear array (MLA) focal plane mechanical and thermal design

Science.gov (United States)

Mitchell, A. S.; Kaminski, E. F.

1982-01-01

The mechanical and thermal design of an integrated focal plane subsystem of a Multispectral Linear Array (MLA) instrument is discussed in terms of focal-plane alignment, thermoelastic performance, and thermal requirements. The modular construction and thermal control of the focal plane array are discussed.

Phase transition in a modified square Josephson-junction array

CERN Document Server

Han, J

1999-01-01

We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.

An electromagnetic spherical phased array thermonuclear fusion reactor

International Nuclear Information System (INIS)

Okress, E.C.

1983-01-01

Discussed are salient physics aspects of a microwave singly reentrant spherical periodic phased array of uniformally distributed identical coaxial radiation elements in an essentially simulated infinite array environment. The array is capable of maintaining coherence or phase control (to the limit of the order of 300 GHz) of its spherically converging electromagnetic transverse magnetic mode radiation field, for confinement (and heating) of thermonuclear plasma in steady-state or inertial thermonuclear fusion. The array also incorporates capability for coaxial directional coupler extraction of fusionpower. The radiation elements of the array are shielded against DT Thermonuclear plasma emissions (i.e., neutrons and bremsstrahlung) by either sufficiently (available) low less tangent and cooled, spherically concentric shield (e.g., Titanium oxide); or alternately by identical material dome windows mounted on each radiation element's aperture of the array. The pump microwave power required for thermonuclear fusion feasibility comprises an array of phase-locked available klystron amplifiers (comparable gyratron amplifiers remain to be developed)

Phased-array design for MST and ST radars

Science.gov (United States)

Ecklund, W. L.

1986-01-01

All of the existing radar systems fully dedicated to clear-air radar studies use some type of phased-array antennas. The effects of beam-steering techniques including feed networks and phase shifters; sidelobe control; ground-clutter suppression; low altitude coverage; arrays with integrated radiating elements and feed networks; analysis of coaxial-collinear antennas; use of arrays with multiple beams; and array testing and measure on structural design of the antenna are discussed.

Optimal array factor radiation pattern synthesis for linear antenna array using cat swarm optimization: validation by an electromagnetic simulator

Institute of Scientific and Technical Information of China (English)

Gopi RAM; Durbadal MANDAL; Sakti Prasad GHOSHAL; Rajib KAR

2017-01-01

In this paper, an optimal design of linear antenna arrays having microstrip patch antenna elements has been carried out. Cat swarm optimization (CSO) has been applied for the optimization of the control parameters of radiation pattern of an antenna array. The optimal radiation patterns of isotropic antenna elements are obtained by optimizing the current excitation weight of each element and the inter-element spacing. The antenna arrays of 12, 16, and 20 elements are taken as examples. The arrays are de-signed by using MATLAB computation and are validated through Computer Simulation Technology-Microwave Studio (CST-MWS). From the simulation results it is evident that CSO is able to yield the optimal design of linear antenna arrays of patch antenna elements.

Design and control of phased ICRF antenna arrays

International Nuclear Information System (INIS)

Goulding, R.H.; Baity, F.W.; Hoffman, D.J.

1993-01-01

Phased antenna arrays operating in the ion cyclotron range of frequencies (ICRF) are used to produce highly directional wave spectra, primarily for use in current drive experiments. RF current drive using phased antennas has been demonstrated in both the JET and DIII-D tokamaks, and both devices are planning to operate new four-element arrays beginning early next year. Features of antenna design that are relevant to phased operation and production of directional spectra are reviewed. Recent advances in the design of the feed circuits and the related control systems for these arrays should substantially improve their performance, by reducing the coupling seen by the matching networks and rf power supplies caused by the mutual impedance of the array elements. The feed circuit designs for the DIII-D and JET phased antenna arrays are compared. The two configurations differ significantly due to the fact that one power amplifier is used for the entire array in the former case, and one per element in the latter. The JET system uses automatic feedback control of matching, phase and amplitude of antenna currents, and the transmitter power balance. The design of this system is discussed, and a time dependent model used to predict its behavior is described

Linear micromechanical stepping drive for pinhole array positioning

International Nuclear Information System (INIS)

Endrödy, Csaba; Mehner, Hannes; Hoffmann, Martin; Grewe, Adrian

2015-01-01

A compact linear micromechanical stepping drive for positioning a 7 × 5.5 mm 2 optical pinhole array is presented. The system features a step size of 13.2 µm and a full displacement range of 200 µm. The electrostatic inch-worm stepping mechanism shows a compact design capable of positioning a payload 50% of its own weight. The stepping drive movement, step sizes and position accuracy are characterized. The actuated pinhole array is integrated in a confocal chromatic hyperspectral imaging system, where coverage of the object plane, and therefore the useful picture data, can be multiplied by 14 in contrast to a non-actuated array. (paper)

Damage detection in multilayered fiber-metal laminates using guided-wave phased array

Energy Technology Data Exchange (ETDEWEB)

Maghsoodi, Ameneh; Ohadi, Abdolrezap; Sadighi, Mojtaba; Amindavar, Hamidreza [Amirkabir University, Tehran (Iran, Islamic Republic of)

2016-05-15

This study employs the Lamb wave method to detect damage in Fiber-metal laminates (FMLs). The method is based on quasiisotropic behavior approximation and beam forming techniques. Delay and sum and minimum variance distorsionless response beam formers are applied to a uniform linear phased array. The simulation in finite element software is conducted to evaluate the performance of the presented procedure. The two types of damage studied are the following: (1) Delamination between fiber-epoxy and metal layers and (2) crack on the metal layer. The present study has the following important contributions: (1) Health monitoring of multi-damaged FMLs using Lamb waves and beam forming technique, (2) detection of damage type, (3) detection of damage size by 1D phased array, and (4) identification of damages that occurred very close to the laminate edges or close to each other.

Isotropic-resolution linear-array-based photoacoustic computed tomography through inverse Radon transform

Science.gov (United States)

Li, Guo; Xia, Jun; Li, Lei; Wang, Lidai; Wang, Lihong V.

2015-03-01

Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.

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

International Nuclear Information System (INIS)

Yu Lili; Shou Wende; Hui Chun

2012-01-01

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. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Phased array antenna control

Science.gov (United States)

Doland, G. D. (Inventor)

1978-01-01

Several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements are provided. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.

Study of Defect Sizing in Carbon Steel Butt Welds using Conventional Ultrasonic Technique and Phased Array Ultrasonic

International Nuclear Information System (INIS)

Amry Amin Abas; Noorhazleena Azaman; Mohd Yusnisyam Mohd Yusoff

2016-01-01

Ultrasonic testing is a proven reliable method which is able to detect and measure the size of defects in butt welds with acceptable tolerance. Recent advancement of technology has introduced a computerized technique which is phased array. Phased array employs focal law that enable focusing and steering of beam at the active aperture axis. This enables one line scanning but covering the whole weld volume as compared to conventional technique which employs aster scan and multiple probes to completely cover the whole weld volume. Phased array also gives multiple data view which assist the interpreter. This paper is about the study of these two techniques and technical analysis of comparison between the two. The conventional technique is performed using GE USM GO with 4 MHz 45 degrees shear wave probe. The phased array technique uses OLYMPUS OMNISCAN MX2 with 5L64 linear array probe with 16 elements aperture and 55 degrees wedge emitting shear wave into the specimen. Sensitivity of both techniques are based on 1.5 mm Side Drilled Hole. The results are compared and analysis such as defect sizing and defect type determination are performed. (author)

Proceedings of the Third EPRI Phased Array Ultrasound Seminar

International Nuclear Information System (INIS)

2003-01-01

Phased array technology for ultrasonic examination is providing innovative solutions for nuclear in-service examination applications. EPRI has been a prime mover in the development and deployment of phased array ultrasound applications in the domestic nuclear market over the past decade. As part of this strategic effort, EPRI has hosted a series of seminars on phased array technology and its applications

Specificity of the Linear Array HPV Genotyping Test for detecting human papillomavirus genotype 52 (HPV-52)

OpenAIRE

Kocjan, Boštjan; Poljak, Mario; Oštrbenk, Anja

2015-01-01

Introduction: HPV-52 is one of the most frequent human papillomavirus (HPV) genotypes causing significant cervical pathology. The most widely used HPV genotyping assay, the Roche Linear Array HPV Genotyping Test (Linear Array), is unable to identify HPV- 52 status in samples containing HPV-33, HPV-35, and/or HPV-58. Methods: Linear Array HPV-52 analytical specificity was established by testing 100 specimens reactive with the Linear Array HPV- 33/35/52/58 cross-reactive probe, but not with the...

Remoting alternatives for a multiple phased-array antenna network

Science.gov (United States)

Shi, Zan; Foshee, James J.

2001-10-01

Significant improvements in technology have made phased array antennas an attractive alternative to the traditional dish antenna for use on wide body airplanes. These improvements have resulted in reduced size, reduced cost, reduced losses in the transmit and receive channels (simplifying the design), a significant extension in the bandwidth capability, and an increase in the functional capability. Flush mounting (thus reduced drag) and rapid beam switching are among the evolving desirable features of phased array antennas. Beam scanning of phased array antennas is limited to +/-45 degrees at best and therefore multiple phased array antennas would need to be used to insure instantaneous communications with any ground station (stations located at different geographical locations on the ground) and with other airborne stations. The exact number of phased array antennas and the specific installation location of each antenna on the wide body airplane would need to be determined by the specific communication requirements, but it is conceivable as many as five phased array antennas may need to be used to provide the required coverage. Control and switching of these antennas would need to be accomplished at a centralized location on the airplane and since these antennas would be at different locations on the airplane an efficient scheme of remoting would need to be used. To save in cost and keep the phased array antennas as small as possible the design of the phased array antennas would need to be kept simple. A dish antenna and a blade antenna (small size) could also be used to augment the system. Generating the RF signals at the central location and then using RF cables or waveguide to get the signal to any given antenna could result in significant RF losses. This paper will evaluate a number of remoting alternatives to keep the system design simple, reduce system cost, and utilize the functional capability of networking multiple phased array antennas on a wide body

Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

International Nuclear Information System (INIS)

Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

2013-01-01

This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects. (paper)

A Ferrite LTCC-Based Monolithic SIW Phased Antenna Array

KAUST Repository

Nafe, Ahmed A.; Ghaffar, Farhan A.; Farooqui, Muhammad Fahad; Shamim, Atif

2016-01-01

In this work, we present a novel configuration for realizing monolithic SIW-based phased antenna arrays using Ferrite LTCC technology. Unlike the current common schemes for realizing SIW phased arrays that rely on surface-mount component (p-i-n diodes, etc) for controlling the phase of the individual antenna elements, here the phase is tuned by biasing of the ferrite filling of the SIW. This approach eliminates the need for mounting of any additional RF components and enables seamless monolithic integration of phase shifters and antennas in SIW technology. As a proof of concept, a two-element slotted SIW-based phased array is designed, fabricated and measured. The prototype exhibits a gain of 4.9 dBi at 13.2 GHz and a maximum E-plane beam-scanning of 28 degrees using external windings for biasing the phase shifters. Moreover, the array can achieve a maximum beam-scanning of 19 degrees when biased with small windings that are embedded in the package. This demonstration marks the first time a fully monolithic SIW-based phased array is realized in Ferrite LTCC technology and paves the way for future larger-size implementations.

A Ferrite LTCC-Based Monolithic SIW Phased Antenna Array

KAUST Repository

Nafe, Ahmed

2016-11-17

In this work, we present a novel configuration for realizing monolithic SIW-based phased antenna arrays using Ferrite LTCC technology. Unlike the current common schemes for realizing SIW phased arrays that rely on surface-mount component (p-i-n diodes, etc) for controlling the phase of the individual antenna elements, here the phase is tuned by biasing of the ferrite filling of the SIW. This approach eliminates the need for mounting of any additional RF components and enables seamless monolithic integration of phase shifters and antennas in SIW technology. As a proof of concept, a two-element slotted SIW-based phased array is designed, fabricated and measured. The prototype exhibits a gain of 4.9 dBi at 13.2 GHz and a maximum E-plane beam-scanning of 28 degrees using external windings for biasing the phase shifters. Moreover, the array can achieve a maximum beam-scanning of 19 degrees when biased with small windings that are embedded in the package. This demonstration marks the first time a fully monolithic SIW-based phased array is realized in Ferrite LTCC technology and paves the way for future larger-size implementations.

Probe suppression in conformal phased array

CERN Document Server

Singh, Hema; Neethu, P S

2017-01-01

This book considers a cylindrical phased array with microstrip patch antenna elements and half-wavelength dipole antenna elements. The effect of platform and mutual coupling effect is included in the analysis. The non-planar geometry is tackled by using Euler's transformation towards the calculation of array manifold. Results are presented for both conducting and dielectric cylinder. The optimal weights obtained are used to generate adapted pattern according to a given signal scenario. It is shown that array along with adaptive algorithm is able to cater to an arbitrary signal environment even when the platform effect and mutual coupling is taken into account. This book provides a step-by-step approach for analyzing the probe suppression in non-planar geometry. Its detailed illustrations and analysis will be a useful text for graduate and research students, scientists and engineers working in the area of phased arrays, low-observables and stealth technology.

A random phased array device for delivery of high intensity focused ultrasound.

Science.gov (United States)

Hand, J W; Shaw, A; Sadhoo, N; Rajagopal, S; Dickinson, R J; Gavrilov, L R

2009-10-07

Randomized phased arrays can offer electronic steering of a single focus and simultaneous multiple foci concomitant with low levels of secondary maxima and are potentially useful as sources of high intensity focused ultrasound (HIFU). This work describes laboratory testing of a 1 MHz random phased array consisting of 254 elements on a spherical shell of radius of curvature 130 mm and diameter 170 mm. Acoustic output power and efficiency are measured for a range of input electrical powers, and field distributions for various single- and multiple-focus conditions are evaluated by a novel technique using an infrared camera to provide rapid imaging of temperature changes on the surface of an absorbing target. Experimental results show that the array can steer a single focus laterally to at least +/-15 mm off axis and axially to more than +/-15 mm from the centre of curvature of the array and patterns of four and five simultaneous foci +/-10 mm laterally and axially whilst maintaining low intensity levels in secondary maxima away from the targeted area in good agreement with linear theoretical predictions. Experiments in which pork meat was thermally ablated indicate that contiguous lesions several cm(3) in volume can be produced using the patterns of multiple foci.

A random phased array device for delivery of high intensity focused ultrasound

International Nuclear Information System (INIS)

Hand, J W; Shaw, A; Sadhoo, N; Rajagopal, S; Dickinson, R J; Gavrilov, L R

2009-01-01

Randomized phased arrays can offer electronic steering of a single focus and simultaneous multiple foci concomitant with low levels of secondary maxima and are potentially useful as sources of high intensity focused ultrasound (HIFU). This work describes laboratory testing of a 1 MHz random phased array consisting of 254 elements on a spherical shell of radius of curvature 130 mm and diameter 170 mm. Acoustic output power and efficiency are measured for a range of input electrical powers, and field distributions for various single- and multiple-focus conditions are evaluated by a novel technique using an infrared camera to provide rapid imaging of temperature changes on the surface of an absorbing target. Experimental results show that the array can steer a single focus laterally to at least ±15 mm off axis and axially to more than ±15 mm from the centre of curvature of the array and patterns of four and five simultaneous foci ±10 mm laterally and axially whilst maintaining low intensity levels in secondary maxima away from the targeted area in good agreement with linear theoretical predictions. Experiments in which pork meat was thermally ablated indicate that contiguous lesions several cm 3 in volume can be produced using the patterns of multiple foci.

An adjustable linear Halbach array

International Nuclear Information System (INIS)

Hilton, J.E.; McMurry, S.M.

2012-01-01

The linear Halbach array is a well-known planar magnetic structure capable, in the idealized case, of generating a one-sided magnetic field. We show that such a field can be created from an array of uniformly magnetized rods, and rotating these rods in an alternating fashion can smoothly transfer the resultant magnetic field through the plane of the device. We examine an idealized model composed of infinite line dipoles and carry out computational simulations on a realizable device using a magnetic boundary element method. Such an arrangement can be used for an efficient latching device, or to produce a highly tunable field in the space above the device. - Highlights: ► We model an adjustable ‘one-sided’ flux sheet made up of a series of dipolar magnetic field sources. ► We show that magnetic field can be switched from one side of sheet to other by a swap rotation of each of magnetic sources. ► Investigations show that such an arrangement is practical and can easily be fabricated. ► The design has a wide range of potential applications.

Electromagnetic linear machines with dual Halbach array design and analysis

CERN Document Server

Yan, Liang; Peng, Juanjuan; Zhang, Lei; Jiao, Zongxia

2017-01-01

This book extends the conventional two-dimensional (2D) magnet arrangement into 3D pattern for permanent magnet linear machines for the first time, and proposes a novel dual Halbach array. It can not only effectively increase the radial component of magnetic flux density and output force of tubular linear machines, but also significantly reduce the axial flux density, radial force and thus system vibrations and noises. The book is also the first to address the fundamentals and provide a summary of conventional arrays, as well as novel concepts for PM pole design in electric linear machines. It covers theoretical study, numerical simulation, design optimization and experimental works systematically. The design concept and analytical approaches can be implemented to other linear and rotary machines with similar structures. The book will be of interest to academics, researchers, R&D engineers and graduate students in electronic engineering and mechanical engineering who wish to learn the core principles, met...

Linear array implementation of the EM algorithm for PET image reconstruction

International Nuclear Information System (INIS)

Rajan, K.; Patnaik, L.M.; Ramakrishna, J.

1995-01-01

The PET image reconstruction based on the EM algorithm has several attractive advantages over the conventional convolution back projection algorithms. However, the PET image reconstruction based on the EM algorithm is computationally burdensome for today's single processor systems. In addition, a large memory is required for the storage of the image, projection data, and the probability matrix. Since the computations are easily divided into tasks executable in parallel, multiprocessor configurations are the ideal choice for fast execution of the EM algorithms. In tis study, the authors attempt to overcome these two problems by parallelizing the EM algorithm on a multiprocessor systems. The parallel EM algorithm on a linear array topology using the commercially available fast floating point digital signal processor (DSP) chips as the processing elements (PE's) has been implemented. The performance of the EM algorithm on a 386/387 machine, IBM 6000 RISC workstation, and on the linear array system is discussed and compared. The results show that the computational speed performance of a linear array using 8 DSP chips as PE's executing the EM image reconstruction algorithm is about 15.5 times better than that of the IBM 6000 RISC workstation. The novelty of the scheme is its simplicity. The linear array topology is expandable with a larger number of PE's. The architecture is not dependant on the DSP chip chosen, and the substitution of the latest DSP chip is straightforward and could yield better speed performance

Numerical implementation of magneto-acousto-electrical tomography (MAET) using a linear phased array transducer

Science.gov (United States)

Soner Gözü, Mehmet; Zengin, Reyhan; Güneri Gençer, Nevzat

2018-02-01

In this study, the performance and implementation of magneto-acousto-electrical tomography (MAET) is investigated using a linear phased array (LPA) transducer. The goal of MAET is to image the conductivity distribution in biological bodies. It uses the interaction between ultrasound and a static magnetic field to generate velocity current density distribution inside the body. The resultant voltage due to velocity current density is sensed by surface electrodes attached on the body. In this study, the theory of MAET is reviewed. A 16-element LPA transducer with 1 MHz excitation frequency is used to provide beam directivity and steerability of acoustic waves. Different two-dimensional numerical models of breast and tumour are formed to analyze the multiphysics problem coupled with acoustics and electromagnetic fields. In these models, velocity current density distributions are obtained for pulse type ultrasound excitations. The static magnetic field is assumed as 1 T. To sense the resultant voltage caused by the velocity current density, it is assumed that two electrodes are attached on the surface of the body. The performance of MAET is shown through sensitivity matrix analysis. The sensitivity matrix is obtained for two transducer positions with 13 steering angles between -30\\circ to 30\\circ with 5\\circ angular intervals. For the reconstruction of the images, truncated singular value decomposition method is used with different signal-to-noise ratio (SNR) values (20 dB, 40 dB, 60 dB and 80 dB). The resultant images show that the perturbation (5 mm  ×  5 mm) placed 35 mm depth can be detected even if the SNR is 20 dB.

Improved SNR of phased-array PERES coils via simulation study

International Nuclear Information System (INIS)

RodrIguez, Alfredo O; Medina, LucIa

2005-01-01

A computational comparison of signal-to-noise ratio (SNR) was performed between a conventional phased array of two circular-shaped coils and a petal resonator surface array. The quasi-static model and phased-array optimum SNR were combined to derive an SNR formula for each array. Analysis of mutual inductance between coil petals was carried out to compute the optimal coil separation and optimum number of petal coils. Mutual interaction between coil arrays was not included in the model because this does not drastically affect coil performance. Phased arrays of PERES coils show a 114% improvement in SNR over that of the simplest circular configuration. (note)

Application of Phased Array Ultrasonic Testing (PAUT) on Single V-Butt Weld Integrity Determination

International Nuclear Information System (INIS)

Amry Amin Abas; Mohd Kamal Shah Shamsudin; Norhazleena Azaman

2015-01-01

Phased Array Ultrasonic Testing (PAUT) utilizes arrays of piezoelectric elements that are embedded in an epoxy base. The benefit of having such kind of array is that beam forming such as steering and focusing the beam front possible. This enables scanning patterns such as linear scan, sectorial scan and depth focusing scan to be performed. Ultrasonic phased array systems can potentially be employed in almost any test where conventional ultrasonic flaw detectors have traditionally been used. Weld inspection and crack detection are the most important applications, and these tests are done across a wide range of industries including aerospace, power generation, petrochemical, metal billet and tubular goods suppliers, pipeline construction and maintenance, structural metals, and general manufacturing. Phased arrays can also be effectively used to profile remaining wall thickness in corrosion survey applications. The benefits of PAUT are simplifying inspection of components of complex geometry, inspection of components with limited access, testing of welds with multiple angles from a single probe and increasing the probability of detection while improving signal-to-noise ratio. This paper compares the result of inspection on several specimens using PAUT as to digital radiography. The specimens are welded plates with single V-butt weld made of carbon steel. Digital radiography is done using blue imaging plate with x-ray source. PAUT is done using Olympus MX2 with 5 MHz probe consisting of 64 elements. The location, size and length of defect is compared. (author)

Code-modulated interferometric imaging system using phased arrays

Science.gov (United States)

Chauhan, Vikas; Greene, Kevin; Floyd, Brian

2016-05-01

Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

An adjustable linear Halbach array

Energy Technology Data Exchange (ETDEWEB)

Hilton, J.E., E-mail: James.Hilton@csiro.au [CSIRO Mathematics, Informatics and Statistics, Clayton South, VIC 3169 (Australia); McMurry, S.M. [School of Physics, Trinity College, Dublin (Ireland)

2012-07-15

The linear Halbach array is a well-known planar magnetic structure capable, in the idealized case, of generating a one-sided magnetic field. We show that such a field can be created from an array of uniformly magnetized rods, and rotating these rods in an alternating fashion can smoothly transfer the resultant magnetic field through the plane of the device. We examine an idealized model composed of infinite line dipoles and carry out computational simulations on a realizable device using a magnetic boundary element method. Such an arrangement can be used for an efficient latching device, or to produce a highly tunable field in the space above the device. - Highlights: Black-Right-Pointing-Pointer We model an adjustable 'one-sided' flux sheet made up of a series of dipolar magnetic field sources. Black-Right-Pointing-Pointer We show that magnetic field can be switched from one side of sheet to other by a swap rotation of each of magnetic sources. Black-Right-Pointing-Pointer Investigations show that such an arrangement is practical and can easily be fabricated. Black-Right-Pointing-Pointer The design has a wide range of potential applications.

Phased Array Radar Network Experiment for Severe Weather

Science.gov (United States)

Ushio, T.; Kikuchi, H.; Mega, T.; Yoshikawa, E.; Mizutani, F.; Takahashi, N.

2017-12-01

Phased Array Weather Radar (PAWR) was firstly developed in 2012 by Osaka University and Toshiba under a grant of NICT using the Digital Beamforming Technique, and showed a impressive thunderstorm behavior with 30 second resolution. After that development, second PAWR was installed in Kobe city about 60 km away from the first PAWR site, and Tokyo Metropolitan University, Osaka Univeristy, Toshiba and the Osaka Local Government started a new project to develop the Osaka Urban Demonstration Network. The main sensor of the Osaka Network is a 2-node Phased Array Radar Network and lightning location system. Data products that are created both in local high performance computer and Toshiba Computer Cloud, include single and multi-radar data, vector wind, quantitative precipitation estimation, VIL, nowcasting, lightning location and analysis. Each radar node is calibarated by the baloon measurement and through the comparison with the GPM (Global Precipitation Measurement)/ DPR (Dual Frequency Space borne Radar) within 1 dB. The attenuated radar reflectivities obtained by the Phased Array Radar Network at X band are corrected based on the bayesian scheme proposed in Shimamura et al. [2016]. The obtained high resolution (every 30 seconds/ 100 elevation angles) 3D reflectivity and rain rate fields are used to nowcast the surface rain rate up to 30 minutes ahead. These new products are transferred to Osaka Local Government in operational mode and evaluated by several section in Osaka Prefecture. Furthermore, a new Phased Array Radar with polarimetric function has been developed in 2017, and will be operated in the fiscal year of 2017. In this presentation, Phased Array Radar, network architecuture, processing algorithm, evalution of the social experiment and first Multi-Prameter Phased Array Radar experiment are presented.

Optically addressed ultra-wideband phased antenna array

Science.gov (United States)

Bai, Jian

Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization

Pattern Synthesis of Dual-band Shared Aperture Interleaved Linear Antenna Arrays

Directory of Open Access Journals (Sweden)

H. Guo

2014-09-01

Full Text Available This paper presents an approach to improve the efficiency of an array aperture by interleaving two different arrays in the same aperture area. Two sub-arrays working at different frequencies are interleaved in the same linear aperture area. The available aperture area is efficiently used. The element positions of antenna array are optimized by using Invasive Weed Optimization (IWO to reduce the peak side lobe level (PSLL of the radiation pattern. To overcome the shortness of traditional methods which can only fulfill the design of shared aperture antenna array working at the same frequency, this method can achieve the design of dual-band antenna array with wide working frequency range. Simulation results show that the proposed method is feasible and efficient in the synthesis of dual-band shared aperture antenna array.

Phased Array Ultrasonic Evaluation of Space Shuttle Main Engine (SSME) Nozzle Weld

Science.gov (United States)

James, Steve; Engel, J.; Kimbrough, D.; Suits, M.; Hopson, George (Technical Monitor)

2001-01-01

This viewgraph presentation gives an overview of the phased array ultrasonic evaluation of the Space Shuttle Main Engine (SSME) nozzle weld. Details are given on the nondestructive testing evaluation approach, conventional shear wave and phased array techniques, and an x-ray versus phased array risk analysis. The field set-up was duplicated to the greatest extent possible in the laboratory and the phased array ultrasonic technique was developed and validated prior to weld evaluation. Results are shown for the phased array ultrasonic evaluation and conventional ultrasonic evaluation results.

Logical Qubit in a Linear Array of Semiconductor Quantum Dots

Directory of Open Access Journals (Sweden)

Cody Jones

2018-06-01

Full Text Available We design a logical qubit consisting of a linear array of quantum dots, we analyze error correction for this linear architecture, and we propose a sequence of experiments to demonstrate components of the logical qubit on near-term devices. To avoid the difficulty of fully controlling a two-dimensional array of dots, we adapt spin control and error correction to a one-dimensional line of silicon quantum dots. Control speed and efficiency are maintained via a scheme in which electron spin states are controlled globally using broadband microwave pulses for magnetic resonance, while two-qubit gates are provided by local electrical control of the exchange interaction between neighboring dots. Error correction with two-, three-, and four-qubit codes is adapted to a linear chain of qubits with nearest-neighbor gates. We estimate an error correction threshold of 10^{-4}. Furthermore, we describe a sequence of experiments to validate the methods on near-term devices starting from four coupled dots.

Evaluation of phased array UT conditions using ultrasonic visualization technique

International Nuclear Information System (INIS)

Furukawa, Takashi; Komura, Ichirou

2008-01-01

Phased array provides many advantages over conventional ultrasonic testing method, but phased array has also limitations. This paper describes typical results of the experimental sound field analysis generated from the array probe. A photo-elastic ultrasonic visualization technique was applied in this study. The sound fields of shear wave generated from the array probe was equivalent to that from the fixed angle probe. (author)

Blending of phased array data

Science.gov (United States)

Duijster, Arno; van Groenestijn, Gert-Jan; van Neer, Paul; Blacquière, Gerrit; Volker, Arno

2018-04-01

The use of phased arrays is growing in the non-destructive testing industry and the trend is towards large 2D arrays, but due to limitations, it is currently not possible to record the signals from all elements, resulting in aliased data. In the past, we have presented a data interpolation scheme `beyond spatial aliasing' to overcome this aliasing. In this paper, we present a different approach: blending and deblending of data. On the hardware side, groups of receivers are blended (grouped) in only a few transmit/recording channels. This allows for transmission and recording with all elements, in a shorter acquisition time and with less channels. On the data processing side, this blended data is deblended (separated) by transforming it to a different domain and applying an iterative filtering and thresholding. Two different filtering methods are compared: f-k filtering and wavefield extrapolation filtering. The deblending and filtering methods are demonstrated on simulated experimental data. The wavefield extrapolation filtering proves to outperform f-k filtering. The wavefield extrapolation method can deal with groups of up to 24 receivers, in a phased array of 48 × 48 elements.

In-phased second harmonic wave array generation with intra-Talbot-cavity frequency-doubling.

Science.gov (United States)

Hirosawa, Kenichi; Shohda, Fumio; Yanagisawa, Takayuki; Kannari, Fumihiko

2015-03-23

The Talbot cavity is one promising method to synchronize the phase of a laser array. However, it does not achieve the lowest array mode with the same phase but the highest array mode with the anti-phase between every two adjacent lasers, which is called out-phase locking. Consequently, their far-field images exhibit 2-peak profiles. We propose intra-Talbot-cavity frequency-doubling. By placing a nonlinear crystal in a Talbot cavity, the Talbot cavity generates an out-phased fundamental wave array, which is converted into an in-phase-locked second harmonic wave array at the nonlinear crystal. We demonstrate numerical calculations and experiments on intra-Talbot-cavity frequency-doubling and obtain an in-phase-locked second harmonic wave array for a Nd:YVO₄ array laser.

MTF measurement and analysis of linear array HgCdTe infrared detectors

Science.gov (United States)

Zhang, Tong; Lin, Chun; Chen, Honglei; Sun, Changhong; Lin, Jiamu; Wang, Xi

2018-01-01

The slanted-edge technique is the main method for measurement detectors MTF, however this method is commonly used on planar array detectors. In this paper the authors present a modified slanted-edge method to measure the MTF of linear array HgCdTe detectors. Crosstalk is one of the major factors that degrade the MTF value of such an infrared detector. This paper presents an ion implantation guard-ring structure which was designed to effectively absorb photo-carriers that may laterally defuse between adjacent pixels thereby suppressing crosstalk. Measurement and analysis of the MTF of the linear array detectors with and without a guard-ring were carried out. The experimental results indicated that the ion implantation guard-ring structure effectively suppresses crosstalk and increases MTF value.

Research on geometric rectification of the Large FOV Linear Array Whiskbroom Image

Science.gov (United States)

Liu, Dia; Liu, Hui-tong; Dong, Hao; Liu, Xiao-bo

2015-08-01

To solve the geometric distortion problem of large FOV linear array whiskbroom image, a model of multi center central projection collinearity equation was founded considering its whiskbroom and linear CCD imaging feature, and the principle of distortion was analyzed. Based on the rectification method with POS, we introduced the angular position sensor data of the servo system, and restored the geometric imaging process exactly. An indirect rectification scheme aiming at linear array imaging with best scanline searching method was adopted, matrixes for calculating the exterior orientation elements was redesigned. We improved two iterative algorithms for this device, and did comparison and analysis. The rectification for the images of airborne imaging experiment showed ideal effect.

Penalized Estimation in Large-Scale Generalized Linear Array Models

DEFF Research Database (Denmark)

Lund, Adam; Vincent, Martin; Hansen, Niels Richard

2017-01-01

Large-scale generalized linear array models (GLAMs) can be challenging to fit. Computation and storage of its tensor product design matrix can be impossible due to time and memory constraints, and previously considered design matrix free algorithms do not scale well with the dimension...

Hierarchical sinuous-antenna phased array for millimeter wavelengths

Science.gov (United States)

Cukierman, Ari; Lee, Adrian T.; Raum, Christopher; Suzuki, Aritoki; Westbrook, Benjamin

2018-03-01

We present the design, fabrication, and measured performance of a hierarchical sinuous-antenna phased array coupled to superconducting transition-edge-sensor (TES) bolometers for millimeter wavelengths. The architecture allows for dual-polarization wideband sensitivity with a beam width that is approximately frequency-independent. We report on measurements of a prototype device, which uses three levels of triangular phased arrays to synthesize beams that are approximately constant in width across three frequency bands covering a 3:1 bandwidth. The array element is a lens-coupled sinuous antenna. The device consists of an array of hemispherical lenses coupled to a lithographed wafer, which integrates TESs, planar sinuous antennas, and microwave circuitry including band-defining filters. The approximately frequency-independent beam widths improve coupling to telescope optics and keep the sensitivity of an experiment close to optimal across a broad frequency range. The design can be straightforwardly modified for use with non-TES lithographed cryogenic detectors such as kinetic inductance detectors. Additionally, we report on the design and measurements of a broadband 180° hybrid that can simplify the design of future multichroic focal planes including but not limited to hierarchical phased arrays.

Waveguide Phased Array Antenna Analysis and Synthesis

NARCIS (Netherlands)

Visser, H.J.; Keizer, W.P.M.N.

1996-01-01

Results of two software packages for analysis and synthesis of waveguide phased array antennas are shown. The antennas consist of arrays of open-ended waveguides where irises can be placed in the waveguide apertures and multiple dielectric sheets in front of the apertures in order to accomplish a

Fabrication of Phased Array EMAT and Its Characteristics

International Nuclear Information System (INIS)

Ahn, Bong Young; Cho, Seung Hyun; Kim, Young Joo; Kim, Ki Bok

2010-01-01

EMAT has been applied in various fields for flaw detection and material characterization because it has noncontact property in wave generation and a good mode selectivity. Unfortunately, however, EMAT shows low signal to noise ratio relative to commercial contact transducer because of low energy conversion efficiency. If the phase matching through the control of time delay between each coil consisting of the array EMAT is accomplished, it is expected that it will be a solution for the improvement of low signal to noise ratio. In this experiment, the phased array EMATs which consists of 3 or 4 meander coils and one big magnet were fabricated for surface and vertical shear wave generation. Effect of phased delay control on signal directivity and amplitude enhancement was verified. A slit with the depth of 0.5 mm and a side-drill hole of 0.5 mm diameter were clearly detected by fabricated phased array EMATs, respectively

Phase-locked, high power, mid-infrared quantum cascade laser arrays

Science.gov (United States)

Zhou, W.; Slivken, S.; Razeghi, M.

2018-04-01

We demonstrate phase-locked, high power quantum cascade laser arrays, which are combined using a monolithic, tree array multimode interferometer, with emission wavelengths around 4.8 μm. A maximum output power of 15 W was achieved from an eight-element laser array, which has only a slightly higher threshold current density and a similar slope efficiency compared to a Fabry-Perot laser of the same length. Calculated multimode interferometer splitting loss is on the order of 0.27 dB for the in-phase supermode. In-phase supermode operation with nearly ideal behavior is demonstrated over the working current range of the array.

Four-to-one power combiner for 20 GHz phased array antenna using RADC MMIC phase shifters

Science.gov (United States)

1991-01-01

The design and microwave simulation of two-to-one microstrip power combiners is described. The power combiners were designed for use in a four element phase array receive antenna subarray at 20 GHz. Four test circuits are described which were designed to enable testing of the power combiner and the four element phased array antenna. Test Circuit 1 enables measurement of the two-to-one power combiner. Test Circuit 2 enables measurement of the four-to-one power combiner. Test Circuit 3 enables measurement of a four element antenna array without phase shifting MMIC's in order to characterize the power combiner with the antenna patch-to-microstrip coaxial feedthroughs. Test circuit 4 is the four element phased array antenna including the RADC MMIC phase shifters and appropriate interconnects to provide bias voltages and control phase bits.

Acoustic emission linear pulse holography

International Nuclear Information System (INIS)

Collins, H.D.; Busse, L.J.; Lemon, D.K.

1983-01-01

This paper describes the emission linear pulse holography which produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. A thirty two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The concept behind the AE linear pulse holography is illustrated, and a block diagram of a data acquisition system to implement the concept is given. Array element spacing, synthetic frequency criteria, and lateral depth resolution are specified. A reference timing transducer positioned between the array and the inspection zone and which inititates the time-of-flight measurements is described. The results graphically illustrate the technique using a one-dimensional FFT computer algorithm (ie. linear backward wave) for an AE image reconstruction

PHARUS : PHased ARray Universal SAR

NARCIS (Netherlands)

Paquay, M.H.A.; Vermeulen, B.C.B.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

1996-01-01

In the Netherlands, a polarimetric C-band aircraft SAR (Synthetic Aperture Radar) has been developed. The project is called PHARUS, an acronm for PHased ARray Universal SAR. This instrument serves remote sensing applications. The antenna system contains 48 active modules (expandable to 96). A module

A Low-Complexity ESPRIT-Based DOA Estimation Method for Co-Prime Linear Arrays.

Science.gov (United States)

Sun, Fenggang; Gao, Bin; Chen, Lizhen; Lan, Peng

2016-08-25

The problem of direction-of-arrival (DOA) estimation is investigated for co-prime array, where the co-prime array consists of two uniform sparse linear subarrays with extended inter-element spacing. For each sparse subarray, true DOAs are mapped into several equivalent angles impinging on the traditional uniform linear array with half-wavelength spacing. Then, by applying the estimation of signal parameters via rotational invariance technique (ESPRIT), the equivalent DOAs are estimated, and the candidate DOAs are recovered according to the relationship among equivalent and true DOAs. Finally, the true DOAs are estimated by combining the results of the two subarrays. The proposed method achieves a better complexity-performance tradeoff as compared to other existing methods.

Two-dimensional Fast ESPRIT Algorithm for Linear Array SAR Imaging

Directory of Open Access Journals (Sweden)

Zhao Yi-chao

2015-10-01

Full Text Available The linear array Synthetic Aperture Radar (SAR system is a popular research tool, because it can realize three-dimensional imaging. However, owning to limitations of the aircraft platform and actual conditions, resolution improvement is difficult in cross-track and along-track directions. In this study, a twodimensional fast Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT algorithm for linear array SAR imaging is proposed to overcome these limitations. This approach combines the Gerschgorin disks method and the ESPRIT algorithm to estimate the positions of scatterers in cross and along-rack directions. Moreover, the reflectivity of scatterers is obtained by a modified pairing method based on “region growing”, replacing the least-squares method. The simulation results demonstrate the applicability of the algorithm with high resolution, quick calculation, and good real-time response.

Airborne electronically steerable phased array

Science.gov (United States)

1972-01-01

The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

Phased Array Antenna Testbed Development at the NASA Glenn Research Center

Science.gov (United States)

Lambert, Kevin M.; Kubat, Gregory; Johnson, Sandra K.; Anzic, Godfrey

2003-01-01

Ideal phased array antennas offer advantages for communication systems, such as wide-angle scanning and multibeam operation, which can be utilized in certain NASA applications. However, physically realizable, electronically steered, phased array antennas introduce additional system performance parameters, which must be included in the evaluation of the system. The NASA Glenn Research Center (GRC) is currently conducting research to identify these parameters and to develop the tools necessary to measure them. One of these tools is a testbed where phased array antennas may be operated in an environment that simulates their use. This paper describes the development of the testbed and its use in characterizing a particular K-Band, phased array antenna.

Low-redundancy linear arrays in mirrored interferometric aperture synthesis.

Science.gov (United States)

Zhu, Dong; Hu, Fei; Wu, Liang; Li, Jun; Lang, Liang

2016-01-15

Mirrored interferometric aperture synthesis (MIAS) is a novel interferometry that can improve spatial resolution compared with that of conventional IAS. In one-dimensional (1-D) MIAS, antenna array with low redundancy has the potential to achieve a high spatial resolution. This Letter presents a technique for the direct construction of low-redundancy linear arrays (LRLAs) in MIAS and derives two regular analytical patterns that can yield various LRLAs in short computation time. Moreover, for a better estimation of the observed scene, a bi-measurement method is proposed to handle the rank defect associated with the transmatrix of those LRLAs. The results of imaging simulation demonstrate the effectiveness of the proposed method.

Position sensor for linear synchronous motors employing halbach arrays

Science.gov (United States)

Post, Richard Freeman

2014-12-23

A position sensor suitable for use in linear synchronous motor (LSM) drive systems employing Halbach arrays to create their magnetic fields is described. The system has several advantages over previously employed ones, especially in its simplicity and its freedom from being affected by weather conditions, accumulated dirt, or electrical interference from the LSM system itself.

Hydrodynamics of single- and two-phase flow in inclined rod arrays

International Nuclear Information System (INIS)

Todreas, N.E.

1984-01-01

Required inputs for thermal-hydraulic codes are constitutive relations for fluid-solid flow resistance, in single-phase flow, and interfacial momentum exchange (relative phase motion), in two-phase flow. An inclined rod array air-water experiment was constructed to study the hydrodynamics of multidimensional porous medium flow in rod arrays. Velocities, pressures, bubble distributions, and void fractions were measured in inline and rotational square rod arrays of P/d = 1.5, at 0, 30, 45, and 90 degree inclinations to the vertical flow direction. Constitutive models for single-phase flow resistance are reviewed, new comprehensive models developed, and an assessment with previously published and new data made. The principle of superimposing one-dimensional correlations proves successful for turbulent single-phase inclined flow. For bubbly two-phase yawed flow through incline rod arrays a new flow separation phenomena was observed and modeled. Bubbles of diameters significantly smaller than the rod diameter travel along the rod axis, while larger diameter bubbles move through the rod array gaps. The outcome is a flow separation not predictable with current interfacial momentum exchange models. This phenomenon was not observed in rotated square rod arrays. Current interfacial momentum exchange models were confirmed for this rod arrangement. Models for the two phase flow resistance multiplier for cross flow were reviewed and compared with data from cross and yawed flow rod arrays. Both drag and lift components of the multiplier were well predicted by the homogenous model. Other models reviewed overpredicted the data by a factor of two

High Rate User Ka-Band Phased Array Antenna Test Results

Science.gov (United States)

Caroglanian, Armen; Perko, Kenneth; Seufert, Steve; Dod, Tom; Warshowsky, Jay; Day, John H. (Technical Monitor)

2001-01-01

The High Rate User Phased Array Antenna (HRUPAA) is a Ka-Band planar phased array designed by the Harris Corporation for the NASA Goddard Space Flight Center. The HRUPAA permits a satellite to downlink data either to a ground station or through the Tracking and Data Relay Satellite System (TDRSS). The HRUPAA is scanned electronically by ground station / user satellite command over a 120 degree cone angle. The phased array has the advantage of not imparting attitude disturbances to the user spacecraft. The 288-element transmit-only array has distributed RF amplifiers integrated behind each of the printed patch antenna elements. The array has 33 dBW EIRP and is left-hand circularly polarized. An engineering model of a partially populated array has been developed and delivered to NASA Goddard Space Flight Center. This report deals with the testing of the engineering model at the Goddard Antenna Range near-field and compact range facilities. The antenna specifications are described first, followed by the test plan and test results.

Optically Controlled Phased Array Antenna

National Research Council Canada - National Science Library

Garafalo, David

1998-01-01

.... The antenna is a 3-foot by 9 foot phased array capable of a scan angle of 120 degrees. The antenna was designed to be conformal to the cargo door of a large aircraft and is designed to operate in the frequency range of 830 - 1400 MHz with a 30...

Phased Array Imaging of Complex-Geometry Composite Components.

Science.gov (United States)

Brath, Alex J; Simonetti, Francesco

2017-10-01

Progress in computational fluid dynamics and the availability of new composite materials are driving major advances in the design of aerospace engine components which now have highly complex geometries optimized to maximize system performance. However, shape complexity poses significant challenges to traditional nondestructive evaluation methods whose sensitivity and selectivity rapidly decrease as surface curvature increases. In addition, new aerospace materials typically exhibit an intricate microstructure that further complicates the inspection. In this context, an attractive solution is offered by combining ultrasonic phased array (PA) technology with immersion testing. Here, the water column formed between the complex surface of the component and the flat face of a linear or matrix array probe ensures ideal acoustic coupling between the array and the component as the probe is continuously scanned to form a volumetric rendering of the part. While the immersion configuration is desirable for practical testing, the interpretation of the measured ultrasonic signals for image formation is complicated by reflection and refraction effects that occur at the water-component interface. To account for refraction, the geometry of the interface must first be reconstructed from the reflected signals and subsequently used to compute suitable delay laws to focus inside the component. These calculations are based on ray theory and can be computationally intensive. Moreover, strong reflections from the interface can lead to a thick dead zone beneath the surface of the component which limits sensitivity to shallow subsurface defects. This paper presents a general approach that combines advanced computing for rapid ray tracing in anisotropic media with a 256-channel parallel array architecture. The full-volume inspection of complex-shape components is enabled through the combination of both reflected and transmitted signals through the part using a pair of arrays held in a yoke

Hydrodynamics of single- and two-phase flow in inclined rod arrays

International Nuclear Information System (INIS)

Ebeling-Koning, D.B.; Todreas, N.E.

1983-09-01

Required inputs for thermal-hydraulic codes are constitutive relations for fluid-solid flow resistance, in single-phase flow, and interfacial momentum exchange (relative phase motion), in two-phase flow. An inclined rod array air-water experiment was constructed to study the hydrodynamics of multidimensional porous medium flow in rod arrays. Velocities, pressures, and bubble distributions were measured in square rod arrays of P/d = 1.5, at 0, 30, 45, and 90 degree inclinations to the vertical flow direction. Constitutive models for single-phase flow resistance are reviewed, new comprehensive models developed, and an assessment with previously published and new data made. The principle of superimposing one-dimensional correlations proves successful for turbulent single-phase inclined flow. For bubbly two-phase incline flow a new flow separation phenomena was observed and modeled. A two-region liquid velocity model is developed to explain the experimentally observed phenomena. Fundamental data for bubbles rising in rod arrays were also taken

A phased array bread board for future remote sensing applications

Science.gov (United States)

Zahn, R. W.; Schmidt, E.

The next generation of SAR antennas will be of the active phased-array type. The ongoing development of a phased-array breadboard for remote sensing is described. Starting from a detailed system design, a functional representative breadboard was developed. The design and the performance of the breadboard are discussed.

PROSPECTS FOR THE DEVELOPMENT OF PHASED ANTENNA ARRAYS

Directory of Open Access Journals (Sweden)

A. P. Dzuba

2013-01-01

Full Text Available This article describes the main achievements in the development of phased antenna arrays (par in the past decade. Provides an overview of the most famous systems based on the PAR and PAR based on MMIC technology - PAR in radar stations, PAR to control the laser and optical beams. The existing options for the design of the PAR:ferroelectric antenna array; plasma antenna with electronic scanning; reflective grating on 100-mm semiconductor wafers; wideband antenna arrays with aperture; antenna arrays with digital beam forming.

Intracavitary ultrasound phased arrays for prostate thermal therapies: MRI compatibility and in vivo testing.

Science.gov (United States)

Hutchinson, E B; Hynynen, K

1998-12-01

A 62 element MRI-compatible linear phased array was designed and constructed to investigate the feasibility of using transrectal ultrasound for the thermal therapeutic treatment of prostate cancer and benign prostatic hyperplasia. An aperiodic design technique developed in a previous study was used in the design of this array, which resulted in reduced grating lobe levels by using an optimized random distribution of unequally sized elements. The element sizes used in this array were selected to be favorable for both grating lobe levels as determined by array aperiodicity and array efficiency as determined by width to thickness ratios. The heating capabilities and MRI compatibility of the array were tested with in vivo rabbit thigh muscle heating experiments using MRI temperature monitoring. The array produced therapeutic temperature elevations in vivo at depths of 3-6 cm and axial locations up to 3 cm off the central axis and increased the size of the heated volume with electronic scanning of a single focus. The ability of this array to be used for ultrasound surgery was demonstrated by creating necrosed tissue lesions in vivo using short high-power sonications. The ability of the array to be used for hyperthermia was demonstrated by inducing therapeutic temperature elevations for longer exposures. Based on the acoustic and heating performance of this array, it has the potential to be clinically useful for delivering thermal therapies to the prostate and other target volumes close to body cavities.

Large-Aperture Membrane Active Phased-Array Antennas

Science.gov (United States)

Karasik, Boris; McGrath, William; Leduc, Henry

2009-01-01

Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

A study for soundness of turbine blade root using ultrasonic and phased array

International Nuclear Information System (INIS)

Gil, Doo Song; Park, Sang Ki; Cho, Yong Sang; Lee, Sang Gug; Huh, Kuang Bum

2003-01-01

Power plant is consisted of many component parts for the generation of the electricity and occasionally, turbine equipment may be caused in break-down because of the damage of the blade root. Phased array ultrasonic testing system has become available for power industry. This research describes the characteristics of phased array ultrasonic testing signal for various type of blade roots in thermal power plant turbines. This application of Phased array ultrasonic testing system has been promoted mainly to save inspection time and labor cost of turbine inspection. The characteristic of phased array ultrasonic testing signal for power plant component in very simple to understand but to difficult for perform the inspection. This paper is focused on the safety of the turbine equipment by the ultrasonic measurement and phased array analysis. As a result of the test through ultrasonic and phased array method, we have concluded that the main damage in these turbine blade roots parts could be generated by the concentrated stress and centrifugal force.

Transverse Oscillations for Phased Array Vector Velocity Imaging

DEFF Research Database (Denmark)

Pihl, Michael Johannes; Jensen, Jørgen Arendt

2010-01-01

of superficial blood vessels. To broaden the usability of the method, it should be expanded to a phased array geometry enabling vector velocity imaging of the heart. Therefore, the scan depth has to be increased to 10-15 cm. This paper presents suitable pulse echo fields (PEF). Two lines are beamformed...... (correlation coefficient, R: -0.76), and therefore predict estimator performance. CV is correlated with the standard deviation (R=0.74). The results demonstrate the potential for using a phased array for vector velocity imaging at larger depths, and potentially for imaging the heart....

Circularly Polarized Planar Helix Phased Antenna Array for 5G Mobile Terminals

DEFF Research Database (Denmark)

Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

2017-01-01

In this paper, a planar helix mobile phased antenna array is proposed for 5th generation communication systems with operating frequency of 28GHz. The proposed array displays circular polarization in the endfire direction. Over 65 degrees of axial ratio beamwidth and 7GHz of axial ratio bandwidth...... has been achieved in the proposed design. The coverage performance of the proposed phased antenna array has also been studied by using the coverage efficiency metric. Coverage efficiency of 50 % at 5 dBi gain is achieved by the proposed phased mobile antenna array....

Pulse Splitting for Harmonic Beamforming in Time-Modulated Linear Arrays

Directory of Open Access Journals (Sweden)

Lorenzo Poli

2014-01-01

Full Text Available A novel strategy for harmonic beamforming in time-modulated linear arrays is proposed. The pulse splitting technique is exploited to simultaneously generate two harmonic patterns, one at the central frequency and another at a preselected harmonic of arbitrary order, while controlling the maximum level of the remaining sideband radiations. An optimization strategy based on the particle swarm optimizer is developed in order to determine the optimal parameters describing the pulse sequence used to modulate the excitation weights of the array elements. Representative numerical results are reported and discussed to point out potentialities and limitations of the proposed approach.

New fabrication of high-frequency (100-MHz) ultrasound PZT film kerfless linear array.

Science.gov (United States)

Zhu, Benpeng; Chan, Ngai Yui; Dai, Jiyan; Shung, K Kirk; Takeuchi, Shinichi; Zhou, Qifa

2013-04-01

The paper describes the design, fabrication, and measurements of a high-frequency ultrasound kerfless linear array prepared from hydrothermal lead zirconate titanate (PZT) thick film. The 15-μm hydrothermal PZT thick film with an area of 1 × 1 cm, obtained through a self-separation process from Ti substrate, was used to fabricate a 32-element 100-MHz kerfless linear array with photolithography. The bandwidth at -6 dB without matching layer, insertion loss around center frequency, and crosstalk between adjacent elements were measured to be 39%, -30 dB, and -15 dB, respectively.

Sampling phased array a new technique for signal processing and ultrasonic imaging

OpenAIRE

Bulavinov, A.; Joneit, D.; Kröning, M.; Bernus, L.; Dalichow, M.H.; Reddy, K.M.

2006-01-01

Different signal processing and image reconstruction techniques are applied in ultrasonic non-destructive material evaluation. In recent years, rapid development in the fields of microelectronics and computer engineering lead to wide application of phased array systems. A new phased array technique, called "Sampling Phased Array" has been developed in Fraunhofer Institute for non-destructive testing. It realizes unique approach of measurement and processing of ultrasonic signals. The sampling...

Small-angle tomography algorithm for transmission inspection of acoustic linear array

Directory of Open Access Journals (Sweden)

Soldatov Alexey

2016-01-01

Full Text Available The paper describes the algorithm of reconstruction of tomographic image used in the through-transition method in a small angle sounding of acoustic linear arrays and the results of practical application of the proposed algorithm. In alternate probing of each element of emitting array and simultaneous reception of all elements of the receiving array is a collection of shadow images of the testing zone. The testing zone is divided into small local areas and using the collection of shadow images computed matrix normalized transmission coefficients for each of the small local area. Tomographic image control zone is obtained by submitting the resulting matrix of normalized transmission coefficients in grayscale or colors.

Phased Array Focusing for Acoustic Wireless Power Transfer.

Science.gov (United States)

Tseng, Victor Farm-Guoo; Bedair, Sarah S; Lazarus, Nathan

2018-01-01

Wireless power transfer (WPT) through acoustic waves can achieve higher efficiencies than inductive coupling when the distance is above several times the transducer size. This paper demonstrates the use of ultrasonic phased arrays to focus power to receivers at arbitrary locations to increase the power transfer efficiency. Using a phased array consisting of 37 elements at a distance nearly 5 times the receiver transducer diameter, a factor of 2.6 increase in efficiency was achieved when compared to a case equivalent to a single large transducer with the same peak efficiency distance. The array has a total diameter of 7 cm, and transmits through air at 40 kHz to a 1.1-cm diameter receiver, achieving a peak overall efficiency of 4% at a distance of 5 cm. By adjusting the focal distance, the efficiency can also be maintained relatively constant at distances up to 9 cm. Numerical models were developed and shown to closely match the experimental energy transfer behavior; modeling results indicate that the efficiency can be further doubled by increasing the number of elements. For comparison, an inductive WPT system was also built with the diameters of the transmitting and receiving coils equivalent to the dimensions of the transmitting ultrasonic phased array and receiver transducer, and the acoustic WPT system achieved higher efficiencies than the inductive WPT system when the transmit-to-receive distance is above 5 cm. In addition, beam angle steering was demonstrated by using a simplified seven-element 1-D array, achieving power transfer less dependent on receiver placement.

Imaging San Jacinto Fault damage zone structure using dense linear arrays: application of ambient noise tomography, Rayleigh wave ellipticity, and site amplification

Science.gov (United States)

Wang, Y.; Lin, F. C.; Allam, A. A.; Ben-Zion, Y.

2017-12-01

The San Jacinto fault is presently the most seismically active component of the San Andreas Transform system in Southern California. To study the damage zone structure, two dense linear geophone arrays (BS and RR) were deployed across the Clark segment of the San Jacinto Fault between Anza and Hemet during winter 2015 and Fall 2016, respectively. Both arrays were 2 km long with 20 m station spacing. Month-long three-component ambient seismic noise data were recorded and used to calculate multi-channel cross-correlation functions. All three-component noise records of each array were normalized simultaneously to retain relative amplitude information between different stations and different components. We observed clear Rayleigh waves and Love waves on the cross-correlations of both arrays at 0.3 - 1 s period. The phase travel times of the Rayleigh waves on both arrays were measured by frequency-time analysis (FTAN), and inverted for Rayleigh wave phase velocity profiles of the upper 500 m depth. For both arrays, we observe prominent asymmetric low velocity zones which narrow with depth. At the BS array near the Hemet Stepover, an approximately 250m wide slow zone is observed to be offset by 75m to the northeast of the surface fault trace. At the RR array near the Anza segment of the fault, a similar low velocity zone width and offset are observed, along with a 10% across-fault velocity contrast. Analyses of Rayleigh wave ellipticity (H/V ratio), Love wave phase travel times, and site amplification are in progress. By using multiple measurements from ambient noise cross-correlations, we can obtain strong constraints on the local damage zone structure of the San Jacinto Fault. The results contribute to improved understanding of rupture directivity, maximum earthquake magnitude and more generally seismic hazard associated with the San Jacinto fault zone.

A study for soundness of turbine blade root using ultrasonic and phased array

International Nuclear Information System (INIS)

Gil, Doo Song; Park, Sang Ki; Cho, Yong Sang; Lee, Sang Gug; Huh, Kuang Bum

2003-01-01

Power plant is consisted of many component parts for the generation of the electricity, and occasionally, turbine equipment may be caused in break-down because of the damage of the blade root. Phased array ultrasonic testing system has become available for practical application in complicated geometry such as turbine blade root, tenon, disc in power industry. This research describes the characteristics of phased array ultrasonic testing signal for various type of blade roots in thermal Power Plant turbines. This application of Phased array ultrasonic testing system has been promoted mainly to save inspection time and labor cost of turbine inspection. The characteristic of phased array ultrasonic testing signal for power plant component in very simple to understand but to difficult for perform the inspection. This paper is focused on the safety of the turbine equipment by the ultrasonic measurement and phased array analysis. As a result of the test through ultrasonic and phased array method, we have concluded that the main damage in these turbine blade root parts could be generated by the concentrated stress and centrifugal force.

Optimal design of a double-sided linear motor with a multi-segmented trapezoidal magnet array for a high precision positioning system

International Nuclear Information System (INIS)

Lee, Moon G.; Gweon, Dae-Gab

2004-01-01

A comparative analysis is performed for linear motors adopting conventional and multi-segmented trapezoidal (MST) magnet arrays, respectively, for a high-precision positioning system. The proposed MST magnet array is a modified version of a Halbach magnet array. The MST array has trapezoidal magnets with variable shape and dimensions while the Halbach magnet array generally has a rectangular magnet with identical dimensions. We propose a new model that can describe the magnetic field resulting from the complex-shaped magnets. The model can be applied to both MST and conventional magnet arrays. Using the model, a design optimization of the two types of linear motors is performed and compared. The magnet array with trapezoidal magnets can produce more force than one with rectangular magnets when they are arrayed in a linear motor where there is a yoke with high permeability. After the optimization and comparison, we conclude that the linear motor with the MST magnet array can generate more actuating force per volume than the motor with the conventional array. In order to satisfy the requirements of next generation systems such as high resolution, high speed, and long stroke, the use of a linear motor with a MST array as an actuator in a high precision positioning system is recommended from the results obtained here

Research on calibration error of carrier phase against antenna arraying

Science.gov (United States)

Sun, Ke; Hou, Xiaomin

2016-11-01

It is the technical difficulty of uplink antenna arraying that signals from various quarters can not be automatically aligned at the target in deep space. The size of the far-field power combining gain is directly determined by the accuracy of carrier phase calibration. It is necessary to analyze the entire arraying system in order to improve the accuracy of the phase calibration. This paper analyzes the factors affecting the calibration error of carrier phase of uplink antenna arraying system including the error of phase measurement and equipment, the error of the uplink channel phase shift, the position error of ground antenna, calibration receiver and target spacecraft, the error of the atmospheric turbulence disturbance. Discuss the spatial and temporal autocorrelation model of atmospheric disturbances. Each antenna of the uplink antenna arraying is no common reference signal for continuous calibration. So it must be a system of the periodic calibration. Calibration is refered to communication of one or more spacecrafts in a certain period. Because the deep space targets are not automatically aligned to multiplexing received signal. Therefore the aligned signal should be done in advance on the ground. Data is shown that the error can be controlled within the range of demand by the use of existing technology to meet the accuracy of carrier phase calibration. The total error can be controlled within a reasonable range.

Shift of the Acoustic Center of a Closed-Box Loudspeaker in a Linear Array: Investigation Using the Beamforming Technique

DEFF Research Database (Denmark)

Chang, Ji-Ho; Jensen, Joe; Agerkvist, Finn T.

2015-01-01

The center of the spherical waves radiated from a loudspeaker is defined as its acoustic center. This study aims to investigate how the acoustic center of a closed-box loudspeaker is shifted when the loudspeaker is placed in a linear array. That is, the acoustic center of the loudspeaker is estim......The center of the spherical waves radiated from a loudspeaker is defined as its acoustic center. This study aims to investigate how the acoustic center of a closed-box loudspeaker is shifted when the loudspeaker is placed in a linear array. That is, the acoustic center of the loudspeaker...... is estimated when the loudspeaker is placed alone and then the loudspeaker is placed in a linear array composed of two or three identical loudspeakers. The acoustic center of each loudspeaker in the linear arrays is estimated with the other loudspeakers turned off and compared with that in the single...... that the acoustic center is shifted differently depending on the relative position of the loudspeaker in the array. This implies that the performance of sound field control with a linear array of loudspeakers can be improved by taking the shift of the acoustic center into account....

Broadband implementation of coprime linear microphone arrays for direction of arrival estimation.

Science.gov (United States)

Bush, Dane; Xiang, Ning

2015-07-01

Coprime arrays represent a form of sparse sensing which can achieve narrow beams using relatively few elements, exceeding the spatial Nyquist sampling limit. The purpose of this paper is to expand on and experimentally validate coprime array theory in an acoustic implementation. Two nested sparse uniform linear subarrays with coprime number of elements ( M and N) each produce grating lobes that overlap with one another completely in just one direction. When the subarray outputs are combined it is possible to retain the shared beam while mostly canceling the other superfluous grating lobes. In this way a small number of microphones ( N+M-1) creates a narrow beam at higher frequencies, comparable to a densely populated uniform linear array of MN microphones. In this work beampatterns are simulated for a range of single frequencies, as well as bands of frequencies. Narrowband experimental beampatterns are shown to correspond with simulated results even at frequencies other than the arrays design frequency. Narrowband side lobe locations are shown to correspond to the theoretical values. Side lobes in the directional pattern are mitigated by increasing bandwidth of analyzed signals. Direction of arrival estimation is also implemented for two simultaneous noise sources in a free field condition.

Linear Array Ambient Noise Adjoint Tomography Reveals Intense Crust-Mantle Interactions in North China Craton

Science.gov (United States)

Zhang, Chao; Yao, Huajian; Liu, Qinya; Zhang, Ping; Yuan, Yanhua O.; Feng, Jikun; Fang, Lihua

2018-01-01

We present a 2-D ambient noise adjoint tomography technique for a linear array with a significant reduction in computational cost and show its application to an array in North China. We first convert the observed data for 3-D media, i.e., surface-wave empirical Green's functions (EGFs) to the reconstructed EGFs (REGFs) for 2-D media using a 3-D/2-D transformation scheme. Different from the conventional steps of measuring phase dispersion, this technology refines 2-D shear wave speeds along the profile directly from REGFs. With an initial model based on traditional ambient noise tomography, adjoint tomography updates the model by minimizing the frequency-dependent Rayleigh wave traveltime delays between the REGFs and synthetic Green functions calculated by the spectral-element method. The multitaper traveltime difference measurement is applied in four-period bands: 20-35 s, 15-30 s, 10-20 s, and 6-15 s. The recovered model shows detailed crustal structures including pronounced low-velocity anomalies in the lower crust and a gradual crust-mantle transition zone beneath the northern Trans-North China Orogen, which suggest the possible intense thermo-chemical interactions between mantle-derived upwelling melts and the lower crust, probably associated with the magmatic underplating during the Mesozoic to Cenozoic evolution of this region. To our knowledge, it is the first time that ambient noise adjoint tomography is implemented for a 2-D medium. Compared with the intensive computational cost and storage requirement of 3-D adjoint tomography, this method offers a computationally efficient and inexpensive alternative to imaging fine-scale crustal structures beneath linear arrays.

Comparison of Thrust Characteristics in Pencil Sized Cylinder-type Linear Motors with Different Magnet Arrays

OpenAIRE

Nakaiwa, K; Yamada, A; Tashiro, K; Wakiwaka, H

2009-01-01

From a strong demand on the miniaturization of a chip mounter or a semiconductor device, the thrust improvement considering the magnets arrangement is studied. We accept a core stator with a Halbach type magnet array for a current linear motor. The thrust characteristics are compared with two kinds of mover, a NS magnet array and a Halbach magnet array.

Mutual-Coupling Based Phased-Array Calibration: A Robust and Versatile Approach

NARCIS (Netherlands)

Bekers, D.J.; Dijk, R. van; Vliet, F.E. van

2013-01-01

The transmit and receive modules of a large phased array are often calibrated for amplitude and phase variations by an internal calibration network and an offline characterization of the complete array in an anechoic chamber. Such a solution is less obvious in view of current trends towards

Investigation of UT procedure for crack depth sizing by phased array UT in Ni-based alloy weld

International Nuclear Information System (INIS)

Hirasawa, Taiji; Fukutomi, Hiroyuki

2013-01-01

Recently, it has been reported that the primary water stress corrosion cracking (PWSCC) has occurred in nickel based alloy weld components such as steam generator safe end weld, reactor vessel safe end weld, and so on, in PWR. Defect detection and sizing are important in order to ensure the reliable operation and life extension of nuclear power plants. In the reactor vessel safe end weld, it was impossible to measure crack depth of PWSCC. The cracks have occurred in the axial direction of the safe end weld. Furthermore, the cracks had some features such as deep, large aspect ratio (ratio of crack depth and length), sharp geometry of crack tip, and so on. Therefore, development and improvement of defect depth sizing capabilities by ultrasonic testing (UT) have been required. Phased array UT technique was applied with regard to defect depth sizing at the inside inspection in Ni-based alloy welds. Phased array UT was examined a standard block specimen with side drilled holes (SDHs). From the experimental results, the performance of linear array probes and dual matrix array probe were investigated. In the basis of the results, UT procedure for defect depth sizing was investigated and proposed. The UT procedure was applied to the defect depth measurement in Ni-based alloy weld specimen with electric discharge machine (EDM) notches. From these results, good accuracy of defect depth sizing by phased array UT for the inside inspection was shown. Therefore, it was clarified the effectiveness of the UT procedure for defect depth sizing in Ni-based alloy weld. (author)

Ku Band Phased Array Feed Development for Surface Water Ocean Topography Mission

Data.gov (United States)

National Aeronautics and Space Administration — The purpose of this project is to design components essential to the development of phased arrays and phased array feeds for use in remote sensing. Specifically the...

Phased-array technology for automatic pipeline inspection; Phased Array-Technologie fuer automatisierte Pipeline-Inspektion

Energy Technology Data Exchange (ETDEWEB)

Bosch, J.; Hugger, A.; Franz, J. [GE Energy, PII Pipetronix GmbH, Stutensee (Germany); Falter, S.; Oberdoerfer, Y. [GE Inspection Technology Systems, Huerth (Germany)

2004-07-01

Pipeline inspection pigs with individual test probes are limited in their function due to the fixed arrangement of sensors on the support. In contrast, the phased-array technology enables multitasking of tests, e.g. stress and corrosion testing which formerly required two different test runs with different sensor set-ups. The angles of inclination can be adapted to the test medium, and virtual sensors can be matched in size and overlap so that, e.g., small pittings will be detected. The sensor set-up presented here enables higher test speed and improved flaw detection. The contribution describes the measuring principle, the inspection pig (UltraScan DUO), and some results of prototype measurements. [German] Pruefmolche fuer die Pipelinepruefung mit Einzelpruefkoepfen sind in ihrem Funktionsumfang aufgrund der festliegenden Anordnung der Sensoren im Sensortraeger eingeschraenkt. Die Phased-Array-Technologie gestattet die simultane Durchfuehrung verschiedener Pruefaufgaben, wie beispielsweise der Rissund der Korrosionspruefung, die vorher zwei Prueflaeufe mit verschiedenen Sensortraegern erforderten. Die Einfallswinkel koennen auf das jeweilige Medium angepasst werden, und es besteht die Moeglichkeit, virtuelle Sensoren bezueglich ihrer Groesse und der gegenseitigen Ueberlappung so anzupassen, dass beispielsweise kleine Pittings gefunden werden koennen. Die ausgefuehrte Form gestattet hoehere Pruefgeschwindigkeit und verbesserte Fehlerauffindung. In diesem Artikel werden das Messprinzip und der Inspektionsmolch (UltraScan DUO) beschrieben sowie einige Prototyp-Messergebnisse vorgestellt.

Ultrasonic phased array examination of circumferential weld joint in reactor pressure vessel of BWR

Energy Technology Data Exchange (ETDEWEB)

Nanekar, Paritosh, E-mail: pnanekar@barc.gov.in [Quality Assurance Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jothilakshmi, N. [Quality Assurance Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

2013-12-15

Highlights: • Phased array technique developed for weld joint inspection in BWR pressure vessel. • Simulation studies were carried out for conventional and phased array probe. • Conventional ultrasonic test shows in-adequate weld coverage and poor resolution. • Focused sound beam in phased array results in good resolution and sensitivity. • Ultrasonic phased array technique is validated on mock-up with reference defects. - Abstract: The weld joints in the reactor pressure vessel (RPV) of Boiling Water Reactors (BWR) are required to be examined periodically for assurance of structural integrity. Ultrasonic phased array examination technique has been developed in authors’ laboratory for inspection of the top flange to shell circumferential weld joint in RPV of BWRs, which are in operation in India since the late 1960s. The development involved detailed simulation studies for computation of focal laws followed by validation on mock-up. The paper brings out the limitations of the conventional ultrasonic technique and how this can be overcome by the phased array approach for the weld joint under consideration. The phased array technique was successfully employed for field examination of this weld joint in RPV during the re-fuelling outage.

Removing Background Noise with Phased Array Signal Processing

Science.gov (United States)

Podboy, Gary; Stephens, David

2015-01-01

Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

Application of phased arrays in basic and in-service inspection

International Nuclear Information System (INIS)

Gebhardt, W.; Schwarz, H.P.; Bonitz, F.; Woll, H.

1985-01-01

In the scope of the reactor safety research program of the Federal Ministry of Research and Technology a flexible microcomputer controlled phased array system was developed. Meanwhile, several industrial prototypes for simple and complicated applications are built up. The applicability of phased array systems in NDE for basic and inservice inspections of reactor pressure vessels is investigated. Methods for defect detection, reconstruction and classification are described

Improvement of ultrasonic testing by use of phased arrays

International Nuclear Information System (INIS)

Gebhardt, W; Bonitz, F.; Woll, H.

1983-01-01

The paper examines the applicability of phased-array technology in non-destructive material testing for quality control, basic inspection and in-service inspections of the primary containment of nuclear power plants. Initial experiments on sonic aigrette control, defect margin reconstruction and the classification of defects have been carried out using medical equipment as commercially available which had been modified for non-destructive applications. At the same time, a for more flexible microcomputer-controlled phased-array system was developed, particularly designed for material testing. (orig./RW) [de

Wavefront sensing and adaptive control in phased array of fiber collimators

Science.gov (United States)

Lachinova, Svetlana L.; Vorontsov, Mikhail A.

2011-03-01

A new wavefront control approach for mitigation of atmospheric turbulence-induced wavefront phase aberrations in coherent fiber-array-based laser beam projection systems is introduced and analyzed. This approach is based on integration of wavefront sensing capabilities directly into the fiber-array transmitter aperture. In the coherent fiber array considered, we assume that each fiber collimator (subaperture) of the array is capable of precompensation of local (onsubaperture) wavefront phase tip and tilt aberrations using controllable rapid displacement of the tip of the delivery fiber at the collimating lens focal plane. In the technique proposed, this tip and tilt phase aberration control is based on maximization of the optical power received through the same fiber collimator using the stochastic parallel gradient descent (SPGD) technique. The coordinates of the fiber tip after the local tip and tilt aberrations are mitigated correspond to the coordinates of the focal-spot centroid of the optical wave backscattered off the target. Similar to a conventional Shack-Hartmann wavefront sensor, phase function over the entire fiber-array aperture can then be retrieved using the coordinates obtained. The piston phases that are required for coherent combining (phase locking) of the outgoing beams at the target plane can be further calculated from the reconstructed wavefront phase. Results of analysis and numerical simulations are presented. Performance of adaptive precompensation of phase aberrations in this laser beam projection system type is compared for various system configurations characterized by the number of fiber collimators and atmospheric turbulence conditions. The wavefront control concept presented can be effectively applied for long-range laser beam projection scenarios for which the time delay related with the double-pass laser beam propagation to the target and back is compared or even exceeds the characteristic time of the atmospheric turbulence change

Bestimmung der optimalen Array-Apertur für die Ultraschallprüfung von faserverstärkten Kunststoffen

OpenAIRE

Kurras, Martin

2017-01-01

Für die zerstörungsfreie Prüfung von Kohlenstofffaserverbundwerkstoffen (CFK) wird häufig die Ultraschallprüfung verwendet. Neben dem klassischen Ultraschallverfahren findet dabei auch die Phased Array Technologie Anwendung. Hierbei wird zwischen zwei Verfahren unterschieden: dem handelsüblichen Phased Array oder Conventional Phased Array (CPA) und dem tomographischen Sampling Phased Array (SPA). Der Einsatz von Phased Arrays im Zusammenhang mit Linear-Scan-Technik und das sich daraus ergeben...

K-Band Phased Array Developed for Low- Earth-Orbit Satellite Communications

Science.gov (United States)

Anzic, Godfrey

1999-01-01

Future rapid deployment of low- and medium-Earth-orbit satellite constellations that will offer various narrow- to wide-band wireless communications services will require phased-array antennas that feature wide-angle and superagile electronic steering of one or more antenna beams. Antennas, which employ monolithic microwave integrated circuits (MMIC), are perfectly suited for this application. Under a cooperative agreement, an MMIC-based, K-band phased-array antenna is being developed with 50/50 cost sharing by the NASA Lewis Research Center and Raytheon Systems Company. The transmitting array, which will operate at 19 gigahertz (GHz), is a state-of-the-art design that features dual, independent, electronically steerable beam operation ( 42 ), a stand-alone thermal management, and a high-density tile architecture. This array can transmit 622 megabits per second (Mbps) in each beam from Earth orbit to small Earth terminals. The weight of the total array package is expected to be less than 8 lb. The tile integration technology (flip chip MMIC tile) chosen for this project represents a major advancement in phased-array engineering and holds much promise for reducing manufacturing costs.

Active phase correction of high resolution silicon photonic arrayed waveguide gratings.

Science.gov (United States)

Gehl, M; Trotter, D; Starbuck, A; Pomerene, A; Lentine, A L; DeRose, C

2017-03-20

Arrayed waveguide gratings provide flexible spectral filtering functionality for integrated photonic applications. Achieving narrow channel spacing requires long optical path lengths which can greatly increase the footprint of devices. High index contrast waveguides, such as those fabricated in silicon-on-insulator wafers, allow tight waveguide bends which can be used to create much more compact designs. Both the long optical path lengths and the high index contrast contribute to significant optical phase error as light propagates through the device. Therefore, silicon photonic arrayed waveguide gratings require active or passive phase correction following fabrication. Here we present the design and fabrication of compact silicon photonic arrayed waveguide gratings with channel spacings of 50, 10 and 1 GHz. The largest device, with 11 channels of 1 GHz spacing, has a footprint of only 1.1 cm2. Using integrated thermo-optic phase shifters, the phase error is actively corrected. We present two methods of phase error correction and demonstrate state-of-the-art cross-talk performance for high index contrast arrayed waveguide gratings. As a demonstration of possible applications, we perform RF channelization with 1 GHz resolution. Additionally, we generate unique spectral filters by applying non-zero phase offsets calculated by the Gerchberg Saxton algorithm.

Simulation Based Investigation of Focusing Phased Array Ultrasound in Dissimilar Metal Welds

Directory of Open Access Journals (Sweden)

Hun-Hee Kim

2016-02-01

Full Text Available Flaws at dissimilar metal welds (DMWs, such as reactor coolant systems components, Control Rod Drive Mechanism (CRDM, Bottom Mounted Instrumentation (BMI etc., in nuclear power plants have been found. Notably, primary water stress corrosion cracking (PWSCC in the DMWs could cause significant reliability problems at nuclear power plants. Therefore, phased array ultrasound is widely used for inspecting surface break cracks and stress corrosion cracks in DMWs. However, inspection of DMWs using phased array ultrasound has a relatively low probability of detection of cracks, because the crystalline structure of welds causes distortion and splitting of the ultrasonic beams which propagates anisotropic medium. Therefore, advanced evaluation techniques of phased array ultrasound are needed for improvement in the probability of detection of flaws in DMWs. Thus, in this study, an investigation of focusing and steering phased array ultrasound in DMWs was carried out using a time reversal technique, and an adaptive focusing technique based on finite element method (FEM simulation. Also, evaluation of focusing performance of three different focusing techniques was performed by comparing amplitude of phased array ultrasonic signals scattered from the targeted flaw with three different time delays.

Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

Science.gov (United States)

Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

2009-01-01

A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

A novel serrated columnar phased array ultrasonic transducer

Science.gov (United States)

Zou, Cheng; Sun, Zhenguo; Cai, Dong; Song, Hongwei; Chen, Qiang

2016-02-01

Traditionally, wedges are required to generate transverse waves in a solid specimen and mechanical rotation device is needed for interrogation of a specimen with a hollow bore, such as high speed railway locomotive axles, turbine rotors, etc. In order to eliminate the mechanical rotation process, a novel array pattern of phased array ultrasonic transducers named as serrated columnar phased array ultrasonic transducer (SCPAUT) is designed. The elementary transducers are planar rectangular, located on the outside surface of a cylinder. This layout is aimed to generate electrically rotating transverse waveforms so as to inspect the longitudinal cracks on the outside surface of a specimen which has a hollow bore at the center, such as the high speed railway locomotive axles. The general geometry of the SCPAUT and the inspection system are illustrated. A FEM model and mockup experiment has been carried out. The experiment results are in good agreement with the FEM simulation results.

A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

Science.gov (United States)

Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

1987-01-01

A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

Microelectromechanical Switches for Phased Array Antennas

Science.gov (United States)

Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

2000-01-01

Preliminary results are presented on the fabrication and testing of a MicroElectro-Mechanical (MEM) microstrip series switch. This switch is being developed for use in a K-band phased array antenna that NASA will use for communication links in its Earth orbiting satellites. Preliminary insertion loss and isolation measurements are presented.

Simulation tools for industrial applications of phased array inspection techniques

International Nuclear Information System (INIS)

Mahaut, St.; Roy, O.; Chatillon, S.; Calmon, P.

2001-01-01

Ultrasonic phased arrays techniques have been developed at the French Atomic Energy Commission in order to improve defects characterization and adaptability to various inspection configuration (complex geometry specimen). Such transducers allow 'standard' techniques - adjustable beam-steering and focusing -, or more 'advanced' techniques - self-focusing on defects for instance -. To estimate the performances of those techniques, models have been developed, which allows to compute the ultrasonic field radiated by an arbitrary phased array transducer through any complex specimen, and to predict the ultrasonic response of various defects inspected with a known beam. Both modeling applications are gathered in the Civa software, dedicated to NDT expertise. The use of those complementary models allows to evaluate the ability of a phased array to steer and focus the ultrasonic beam, and therefore its relevancy to detect and characterize defects. These models are specifically developed to give accurate solutions to realistic inspection applications. This paper briefly describes the CIVA models, and presents some applications dedicated to the inspection of complex specimen containing various defects with a phased array used to steer and focus the beam. Defect detection and characterization performances are discussed for the various configurations. Some experimental validation of both models are also presented. (authors)

Aliasing in the Complex Cepstrum of Linear-Phase Signals

DEFF Research Database (Denmark)

Bysted, Tommy Kristensen

1997-01-01

Assuming linear-phase of the associated time signal, this paper presents an approximated analytical description of the unavoidable aliasing in practical use of complex cepstrums. The linear-phase assumption covers two major applications of complex cepstrums which are linear- to minimum-phase FIR......-filter transformation and minimum-phase estimation from amplitude specifications. The description is made in the cepstrum domain, the Fourier transform of the complex cepstrum and in the frequency domain. Two examples are given, one for verification of the derived equations and one using the description to reduce...... aliasing in minimum-phase estimation...

Nonequilibrium phase transitions in finite arrays of globally coupled Stratonovich models: strong coupling limit

International Nuclear Information System (INIS)

Senf, Fabian; Altrock, Philipp M; Behn, Ulrich

2009-01-01

A finite array of N globally coupled Stratonovich models exhibits a continuous nonequilibrium phase transition. In the limit of strong coupling, there is a clear separation of timescales of centre of mass and relative coordinates. The latter relax very fast to zero and the array behaves as a single entity described by the centre of mass coordinate. We compute analytically the stationary probability distribution and the moments of the centre of mass coordinate. The scaling behaviour of the moments near the critical value of the control parameter a c (N) is determined. We identify a crossover from linear to square root scaling with increasing distance from a c . The crossover point approaches a c in the limit N→∞ which reproduces previous results for infinite arrays. Our results are obtained in both the Fokker-Planck and the Langevin approach and are corroborated by numerical simulations. For a general class of models we show that the transition manifold in the parameter space depends on N and is determined by the scaling behaviour near a fixed point of the stochastic flow.

Image-Guided Surgery of Primary Breast Cancer Using Ultrasound Phased Arrays

National Research Council Canada - National Science Library

Ebbini, Emad S

2004-01-01

.... Piezocomposite transducer technology, especially for phased arrays, is providing high-quality HIFU applicators with increased bandwidth and reduced parasitic cross coupling between the array elements...

A general technique for characterizing x-ray position sensitive arrays

International Nuclear Information System (INIS)

Dufresne, E.; Bruning, R.; Sutton, M.; Stephenson, G.B.

1994-03-01

We present a general statistical technique for characterizing x-ray sensitive linear diode arrays and CCD arrays. We apply this technique to characterize the response of a linear diode array, Princeton Instrument model X-PDA, and a virtual phase CCD array, TI 4849, to direct illumination by x-rays. We find that the response of the linear array is linearly proportional to the incident intensity and uniform over its length to within 2 %. Its quantum efficiency is 38 % for Cu K α x-rays. The resolution function is evaluated from the spatial autocorrelation function and falls to 10 % of its peak value after one pixel. On the other hand, the response of the CCD detecting system to direct x-ray exposure is non-linear. To properly quantify the scattered x-rays, one must correct for the non- linearity. The resolution is two pixels along the serial transfer direction. We characterize the noise of the CCD and propose a model that takes into account the non-linearity and the resolution function to estimate the quantum efficiency of the detector. The quantum efficiency is 20 %

Adaptive ground implemented phase array

Science.gov (United States)

Spearing, R. E.

1973-01-01

The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.

5G antenna array with wide-angle beam steering and dual linear polarizations

KAUST Repository

Klionovski, Kirill

2017-10-25

In this paper, we present the design of a switched-beam antenna array at millimeter-wave frequencies for future 5G applications. The proposed antenna array is based on wideband patch antenna elements and a Butler matrix feed network. The patch antenna has a broad radiation pattern for wide-angle beam steering and allows the simultaneous operation with two orthogonal linear polarizations. A combination of two separated Butler matrices provides independent beam steering for both polarizations in the wide operating band. The antenna array has a simple multilayer construction, and it is made on a low-cost Rogers laminate.

5G antenna array with wide-angle beam steering and dual linear polarizations

KAUST Repository

Klionovski, Kirill; Shamim, Atif; Sharawi, Mohammad Said

2017-01-01

In this paper, we present the design of a switched-beam antenna array at millimeter-wave frequencies for future 5G applications. The proposed antenna array is based on wideband patch antenna elements and a Butler matrix feed network. The patch antenna has a broad radiation pattern for wide-angle beam steering and allows the simultaneous operation with two orthogonal linear polarizations. A combination of two separated Butler matrices provides independent beam steering for both polarizations in the wide operating band. The antenna array has a simple multilayer construction, and it is made on a low-cost Rogers laminate.

Multilevel photonic modules for millimeter-wave phased-array antennas

Science.gov (United States)

Paolella, Arthur C.; Bauerle, Athena; Joshi, Abhay M.; Wright, James G.; Coryell, Louis A.

2000-09-01

Millimeter wave phased array systems have antenna element sizes and spacings similar to MMIC chip dimensions by virtue of the operating wavelength. Designing modules in traditional planar packaing techniques are therefore difficult to implement. An advantageous way to maintain a small module footprint compatible with Ka-Band and high frequency systems is to take advantage of two leading edge technologies, opto- electronic integrated circuits (OEICs) and multilevel packaging technology. Under a Phase II SBIR these technologies are combined to form photonic modules for optically controlled millimeter wave phased array antennas. The proposed module, consisting of an OEIC integrated with a planar antenna array will operate on the 40GHz region. The OEIC consists of an InP based dual-depletion PIN photodetector and distributed amplifier. The multi-level module will be fabricated using an enhanced circuit processing thick film process. Since the modules are batch fabricated using an enhanced circuit processing thick film process. Since the modules are batch fabricated, using standard commercial processes, it has the potential to be low cost while maintaining high performance, impacting both military and commercial communications systems.

Non-destructive evaluation of welding part of stainless steels by phased array system

International Nuclear Information System (INIS)

Tatematsu, Nobuhiro; Matsumoto, Eiji

2009-01-01

Recently, more accurate and convenient Non-Destructive Evaluation techniques are required for flaw inspection of structural materials. Phased array ultrasonic transducers are expected as such as NDE technique but there are many subjects to be solved. Furthermore, commercial phased array systems with conventional scanning and imaging techniques have not fulfilled their maximum potential. The purpose of this paper is to improve the phased array system to be applicable to the inhomogeneity evaluation of welding part of stainless steels. (author)

Application of immersion phased array UT technique in nickel based alloy weld

International Nuclear Information System (INIS)

Hirasawa, Taiji; Nagai, Satoshi; Murakami, Koji; Yuguchi, Yasuhiro; Ootsubo, Tooru; Naruse, Katsuhiko

2007-01-01

The improvement of defect detection and sizing capabilities for nondestructive inspection technique has been required in order to ensure the reliable operation and life extension of nuclear power plant. Immersion phased array UT technique which is not affected the surface geometry of welds has been developed for inspection of BWR internals such as shroud, shroud support, and so on. Phased array UT technique was applied for shroud support mockup specimen with fatigue crack and partially SCC. From the experimental results, the superior performance of phased array UT for the RPV outside and inside inspection was shown. (author)

ZnO nanorod array polydimethylsiloxane composite solid phase micro-extraction fiber coating: fabrication and extraction capability.

Science.gov (United States)

Wang, Dan; Wang, Qingtang; Zhang, Zhuomin; Chen, Guonan

2012-01-21

ZnO nanorod array coating is a novel kind of solid-phase microextraction (SPME) fiber coating which shows good extraction capability due to the nanostructure. To prepare the composite coating is a good way to improve the extraction capability. In this paper, the ZnO nanorod array polydimethylsiloxane (PDMS) composite SPME fiber coating has been prepared and its extraction capability for volatile organic compounds (VOCs) has been studied by headspace sampling the typical volatile mixed standard solution of benzene, toluene, ethylbenzene and xylene (BTEX). Improved detection limit and good linear ranges have been achieved for this composite SPME fiber coating. Also, it is found that the composite SPME fiber coating shows good extraction selectivity to the VOCs with alkane radicals.

A METHOD FOR SELF-CALIBRATION IN SATELLITE WITH HIGH PRECISION OF SPACE LINEAR ARRAY CAMERA

Directory of Open Access Journals (Sweden)

W. Liu

2016-06-01

Full Text Available At present, the on-orbit calibration of the geometric parameters of a space surveying camera is usually processed by data from a ground calibration field after capturing the images. The entire process is very complicated and lengthy and cannot monitor and calibrate the geometric parameters in real time. On the basis of a large number of on-orbit calibrations, we found that owing to the influence of many factors, e.g., weather, it is often difficult to capture images of the ground calibration field. Thus, regular calibration using field data cannot be ensured. This article proposes a real time self-calibration method for a space linear array camera on a satellite using the optical auto collimation principle. A collimating light source and small matrix array CCD devices are installed inside the load system of the satellite; these use the same light path as the linear array camera. We can extract the location changes of the cross marks in the matrix array CCD to determine the real-time variations in the focal length and angle parameters of the linear array camera. The on-orbit status of the camera is rapidly obtained using this method. On one hand, the camera’s change regulation can be mastered accurately and the camera’s attitude can be adjusted in a timely manner to ensure optimal photography; in contrast, self-calibration of the camera aboard the satellite can be realized quickly, which improves the efficiency and reliability of photogrammetric processing.

Characterisation of ultrasonic structural noise in multiple scattering media using phased arrays

International Nuclear Information System (INIS)

Bedetti, T; Dorval, V; Jenson, F; Derode, A

2013-01-01

The ultrasonic inspection of multiple scattering media gives rise to structural noise which makes it difficult to detect potential damage or crack inside the component. In order to predict the performances of ultrasonic inspection over such complex media, scattering models can be used. Such models rely on specific key parameters describing the multiple scattering process, which can be determined by specific measurements and post-processing techniques. Such experiments were carried out on stainless steel plates using linear phased-arrays. They consist in recording the response matrix constituted by impulse responses between all the elements of the array. By conducting post-processing on this matrix, we measure the elastic mean free path l e and the correlation distance d c of the recorded noise. Additionally, the dynamic behaviour of the coherent backscattering effect was studied in order to measure the diffusion constant D. Plane-wave beamforming has been applied to the response matrix to improve the angular resolution and the signal-to-noise ratio of the backscattered intensity. Details of postprocessing techniques will be shown

Substrate Integrated Waveguide Based Phase Shifter and Phased Array in a Ferrite Low Temperature Co-fired Ceramic Package

KAUST Repository

Nafe, Ahmed A.

2014-03-01

Phased array antennas, capable of controlling the direction of their radiated beam, are demanded by many conventional as well as modern systems. Applications such as automotive collision avoidance radar, inter-satellite communication links and future man-portable satellite communication on move services require reconfigurable beam systems with stress on mobility and cost effectiveness. Microwave phase shifters are key components of phased antenna arrays. A phase shifter is a device that controls the phase of the signal passing through it. Among the technologies used to realize this device, traditional ferrite waveguide phase shifters offer the best performance. However, they are bulky and difficult to integrate with other system components. Recently, ferrite material has been introduced in Low Temperature Co-fired Ceramic (LTCC) multilayer packaging technology. This enables the integration of ferrite based components with other microwave circuitry in a compact, light-weight and mass producible package. Additionally, the recent concept of Substrate Integrated Waveguide (SIW) allowed realization of synthesized rectangular waveguide-like structures in planar and multilayer substrates. These SIW structures have been shown to maintain the merits of conventional rectangular waveguides such as low loss and high power handling capabilities while being planar and easily integrable with other components. Implementing SIW structures inside a multilayer ferrite LTCC package enables monolithic integration of phase shifters and phased arrays representing a true System on Package (SoP) solution. It is the objective of this thesis to pursue realizing efficient integrated phase shifters and phased arrays combining the above mentioned technologies, namely Ferrite LTCC and SIW. In this work, a novel SIW phase shifter in ferrite LTCC package is designed, fabricated and tested. The device is able to operate reciprocally as well as non-reciprocally. Demonstrating a measured maximum

Depscor-95 Agile Optical Phased Arrays for Microspacecraft

National Research Council Canada - National Science Library

Fork, Richard

1999-01-01

... average power beams with little or no mechanical movement are especially interesting. Recent advances in semiconductor and optical fiber lasers suggest lightweight compact optical phased arrays suitable for microspacecraft are feasible...

CFD Analysis of a Finite Linear Array of Savonius Wind Turbines

Science.gov (United States)

Belkacem, Belabes; Paraschivoiu, Marius

2016-09-01

Vertical axis wind turbines such as Savonius rotors have been shown to be suitable for low wind speeds normally associated with wind resources in all corners of the world. However, the efficiency of the rotor is low. This paper presents results of Computational Fluid Dynamics (CFD) simulations for an array of Savonius rotors that show a significant increase in efficiency. It looks at identifying the effect on the energy yield of a number of turbines placed in a linear array. Results from this investigation suggest that an increase in the energy yield could be achieved which can reach almost two times than the conventional Savonius wind turbine in the case of an array of 11turbines with a distance of 1.4R in between them. The effect of different TSR values and different wind inlet speeds on the farm has been studied for both a synchronous and asynchronous wind farm.

A proof of the Woodward-Lawson sampling method for a finite linear array

Science.gov (United States)

Somers, Gary A.

1993-01-01

An extension of the continuous aperture Woodward-Lawson sampling theorem has been developed for a finite linear array of equidistant identical elements with arbitrary excitations. It is shown that by sampling the array factor at a finite number of specified points in the far field, the exact array factor over all space can be efficiently reconstructed in closed form. The specified sample points lie in real space and hence are measurable provided that the interelement spacing is greater than approximately one half of a wavelength. This paper provides insight as to why the length parameter used in the sampling formulas for discrete arrays is larger than the physical span of the lattice points in contrast with the continuous aperture case where the length parameter is precisely the physical aperture length.

Diode array pumped, non-linear mirror Q-switched and mode-locked

Indian Academy of Sciences (India)

A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while ...

Optimal linear generator with Halbach array for harvesting of vibration energy during human walking

Directory of Open Access Journals (Sweden)

Joonsoo Jun

2016-05-01

Full Text Available In IT business, the capacity of the battery in smartphone was drastically improved to digest various functions such as communication, Internet, e-banking, and entertainment. Although the capacity of the battery is improved, it still needs to be upgraded due to customer’s demands. In this article, we optimize the design of the linear generator with the Halbach array to improve the efficiency of harvesting vibration energy during human walking for the battery capacitance. We propose the optimal design of the tubular permanent magnet with the linear generator that uses a Halbach array. The approximate model is established using generic algorithm. Furthermore, we performed electromagnetic finite element analysis to predict the induced voltage.

Spectrally resolved modal characteristics of leaky-wave-coupled quantum cascade phase-locked laser arrays

Science.gov (United States)

Sigler, Chris; Gibson, Ricky; Boyle, Colin; Kirch, Jeremy D.; Lindberg, Donald; Earles, Thomas; Botez, Dan; Mawst, Luke J.; Bedford, Robert

2018-01-01

The modal characteristics of nonresonant five-element phase-locked arrays of 4.7-μm emitting quantum cascade lasers (QCLs) have been studied using spectrally resolved near- and far-field measurements and correlated with results of device simulation. Devices are fabricated by a two-step metal-organic chemical vapor deposition process and operate predominantly in an in-phase array mode near threshold, although become multimode at higher drive levels. The wide spectral bandwidth of the QCL's core region is found to be a factor in promoting multispatial-mode operation at high drive levels above threshold. An optimized resonant-array design is identified to allow sole in-phase array-mode operation to high drive levels above threshold, and indicates that for phase-locked laser arrays full spatial coherence to high output powers does not require full temporal coherence.

Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas

Science.gov (United States)

Poduval, Dhruva

Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must be understood and optimized under multiple design constraints, e.g. substrate material properties and thicknesses, element to element spacing, and feed lines and their orientation and arrangements with respect to the antenna elements. The focus of this thesis is to investigate, design, and develop an aperture coupled patch array with wide operating bandwidth (30%), high gain (17.5 dBi), low side lobe level (20 dB), and high Forward to Backward (F/B) ratio (21.8 dB). The target frequency range is 2.4 to 3 GHz given its wide application in WLAN, LTE (Long Term Evolution) and other communication systems. Notwithstanding that the design concept can very well be adapted at other frequencies. Specifically, a 16 element, 4 by 4 planar microstrip patch array is designed using HFSS and experimentally developed and tested. Starting from mutual coupling minimization a corporate feeding scheme is designed to achieve the needed performance. To reduce the SLL the corporate feeding network is redesigned to obtain a specific amplitude taper. Studies are conducted to determine the optimum location for a metallic reflector under the feed line to improve the F/B. An experimental prototype of the antenna was built and tested validating and demonstrating the performance levels expected from simulation predictions

Improved linear pyroelectric IR detector arrays

International Nuclear Information System (INIS)

Twiney, R.C.; Robinson, M.K.; Porter, S.G.

1987-01-01

Good agreement has been found between theoretical models and measured performance for a range of array geometries. A 64-element 80 x 140-micron element array with integral MOSFET IC buffer preamplifiers shows improved source voltage uniformity, a J-FET buffered array, and low-frequency specific detectivity (SD) of 1.7 x 10 to the 8th cm sq rt Hz/W at 40 Hz. The MOSFET array shows reduced degradation of SD at high temperatures, retaining an SD of not less than 1 x 10 to the 8th cm sq rt Hz/W at +70 C across much of the band. A 64-element array has been designed using onboard multiplexers, thus greatly reducing the connections needed to run the array

FY15 Status of Immersion Phased Array Ultrasonic Probe Development and Performance Demonstration Results for Under Sodium Viewing

Energy Technology Data Exchange (ETDEWEB)

Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Larche, Michael R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mathews, Royce [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Neill, Kevin J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Baldwin, David L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prowant, Matthew S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Edwards, Matthew K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chamberlin, Clyde E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-09-01

This Technical Letter Report (TLR) describes work conducted at the Pacific Northwest National Laboratory (PNNL) during FY 2015 on the under-sodium viewing (USV) PNNL project 58745, Work Package AT-15PN230102. This TLR satisfies PNNL’s M3AT-15PN2301027 milestone, and is focused on summarizing the design, development, and evaluation of a two-dimensional matrix phased-array probe referred to as serial number 3 (SN3). In addition, this TLR also provides the results from a performance demonstration of in-sodium target detection trials at 260°C using a one-dimensional 22-element linear array developed in FY14 and referred to as serial number 2 (SN2).

CFD Analysis of a Finite Linear Array of Savonius Wind Turbines

International Nuclear Information System (INIS)

Belkacem, Belabes; Paraschivoiu, Marius

2016-01-01

Vertical axis wind turbines such as Savonius rotors have been shown to be suitable for low wind speeds normally associated with wind resources in all corners of the world. However, the efficiency of the rotor is low. This paper presents results of Computational Fluid Dynamics (CFD) simulations for an array of Savonius rotors that show a significant increase in efficiency. It looks at identifying the effect on the energy yield of a number of turbines placed in a linear array. Results from this investigation suggest that an increase in the energy yield could be achieved which can reach almost two times than the conventional Savonius wind turbine in the case of an array of 11turbines with a distance of 1.4R in between them. The effect of different TSR values and different wind inlet speeds on the farm has been studied for both a synchronous and asynchronous wind farm. (paper)

Noise analysis and performance of a selfscanned linear InSb detector array

International Nuclear Information System (INIS)

Finger, G.; Meyer, M.; Moorwood, A.F.M.

1987-01-01

A noise model for detectors operated in the capacitive discharge mode is presented. It is used to analyze the noise performance of the ESO nested timing readout technique applied to a linear 32-element InSb array which is multiplexed by a silicon switched-FET shift register. Analysis shows that KTC noise of the videoline is the major noise contribution; it can be eliminated by weighted double-correlated sampling. Best noise performance of this array is achieved at the smallest possible reverse bias voltage (not more than 20 mV) whereas excess noise is observed at higher reverse bias voltages. 5 references

Continuous-Scan Phased Array Measurement Methods for Turbofan Engine Acoustic Testing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — ATA Engineering, Inc., (ATA) proposes an SBIR project to advance the technology readiness level (TRL) of a method for measuring phased array acoustic data for...

A fourth gradient to overcome slice dependent phase effects of voxel-sized coils in planar arrays.

Science.gov (United States)

Bosshard, John C; Eigenbrodt, Edwin P; McDougall, Mary P; Wright, Steven M

2010-01-01

The signals from an array of densely spaced long and narrow receive coils for MRI are complicated when the voxel size is of comparable dimension to the coil size. The RF coil causes a phase gradient across each voxel, which is dependent on the distance from the coil, resulting in a slice dependent shift of k-space. A fourth gradient coil has been implemented and used with the system's gradient set to create a gradient field which varies with slice. The gradients are pulsed together to impart a slice dependent phase gradient to compensate for the slice dependent phase due to the RF coils. However the non-linearity in the fourth gradient which creates the desired slice dependency also results in a through-slice phase ramp, which disturbs normal slice refocusing and leads to additional signal cancelation and reduced field of view. This paper discusses the benefits and limitations of using a fourth gradient coil to compensate for the phase due to RF coils.

An Optimal DEM Reconstruction Method for Linear Array Synthetic Aperture Radar Based on Variational Model

Directory of Open Access Journals (Sweden)

Shi Jun

2015-02-01

Full Text Available Downward-looking Linear Array Synthetic Aperture Radar (LASAR has many potential applications in the topographic mapping, disaster monitoring and reconnaissance applications, especially in the mountainous area. However, limited by the sizes of platforms, its resolution in the linear array direction is always far lower than those in the range and azimuth directions. This disadvantage leads to the blurring of Three-Dimensional (3D images in the linear array direction, and restricts the application of LASAR. To date, the research on 3D SAR image enhancement has focused on the sparse recovery technique. In this case, the one-to-one mapping of Digital Elevation Model (DEM brakes down. To overcome this, an optimal DEM reconstruction method for LASAR based on the variational model is discussed in an effort to optimize the DEM and the associated scattering coefficient map, and to minimize the Mean Square Error (MSE. Using simulation experiments, it is found that the variational model is more suitable for DEM enhancement applications to all kinds of terrains compared with the Orthogonal Matching Pursuit (OMPand Least Absolute Shrinkage and Selection Operator (LASSO methods.

Development and applications of a computer-aided phased array assembly for ultrasonic testing

International Nuclear Information System (INIS)

Schenk, G.; Montag, H.J.; Wuestenberg, H.; Erhard, A.

1985-01-01

The use of modern electronic equipment for programmable signal delay increasingly allows transit-time controlled phased arrays to be applied in non-destructive, ultrasonic materials testing. A phased-array assembly is described permitting fast variation of incident angle of acoustic wave and of sonic beam focus, together with numerical evaluation of measured data. Phased arrays can be optimized by adding programmable electronic equipment so that the quality of conventional designs can be achieved. Applications of the new technical improvement are explained, referring to stress corrosion cracking, turbine testing, echo tomography of welded joints. (orig./HP) [de

Phase Synchronization for the Mid-Frequency Square Kilometre Array Telescope

Science.gov (United States)

Schediwy, Sascha; Gozzard, David; Stobie, Simon; Gravestock, Charles; Whitaker, Richard; Alachkar, Bassem; Malan, Sias; Boven, Paul; Grainge, Keith

2018-01-01

The Square Kilometre Array (SKA) project is an international effort to build the world’s most sensitive radio telescope operating in the 50 MHz to 14 GHz frequency range. Construction of the SKA has been divided into phases, with the first phase (SKA1) accounting for the first 10% of the telescope's receiving capacity. During SKA1, a low-frequency aperture array comprising over a hundred thousand individual dipole antenna elements will be constructed in Western Australia (SKA1-low), while an array of 197 parabolic-dish antennas, incorporating the 64 dishes of MeerKAT, will be constructed in South Africa (SKA1-mid).Radio telescope arrays such as the SKA require phase-coherent reference signals to be transmitted to each antenna site in the array. In the case of the SKA1-mid, these reference signals will be generated at a central site and transmitted to the antenna sites via fiber-optic cables up to 175 km in length. Environmental perturbations affect the optical path length of the fiber and act to degrade the phase stability of the reference signals received at the antennas, which has the ultimate effect of reducing the fidelity and dynamic range of the data.Since 2011, researchers at the University of Western Australia (UWA) have led the development of an actively-stabilized phase-synchronization system designed specifically to meet the scientific needs and technical challenges of the SKA telescope. Recently this system has been select as the official phase synchronization system for the SKA1-mid telescope. The system is an evolution of Atacama Large Millimeter Array’s distributed ‘photonic local oscillator system’, incorporating key advances made by the international frequency metrology community over the last decade, as well as novel innovations developed by UWA researchers.In this presentation I will describe the technical details of the system; outline how the system's performance was tested using metrology techniques in a laboratory setting, on 186 km

An ultrasonic phased array applicator for deep localized hyperthermia

International Nuclear Information System (INIS)

Ocheltree, K.B.; Benkeser, P.J.; Foster, S.G.; Frizzell, L.A.; Cain, C.A.

1984-01-01

The use of an ultrasonic phased array applicator presents a major advantage over the fixed beam ultrasonic applicators which are typically used for clinical hyperthermia. Such an applicator allows focal region placement in the three dimensional treatment field by electronic steering instead of mechanical movement of the transducer assembly. The design of an array is discussed theoretically, considering that the constraints on grating lobes and power output for hyperthermic applications are quite different from those for imaging. The effects of various design parameters are discussed. Experimental results are presented for several arrays for frequencies under 1 Mhz

Multiobjective Optimization Method for Multichannel Microwave Components of Active Phased Array Antenna

Directory of Open Access Journals (Sweden)

Lu Wang

2016-01-01

Full Text Available Multichannel microwave components are widely used and the active phased array antenna is a typical representative. The high power generated from T/R modules in active phased array antenna (APAA leads to the degradation of its electrical performances, which seriously restricts the development of high-performance APAA. Therefore, to meet the demand of thermal design for APAA, a multiobjective optimization design model of cold plate is proposed. Furthermore, in order to achieve temperature uniformity and case temperature restrictions of APAA simultaneously, optimization model of channel structure is developed. Besides, an airborne active phased array antenna was tested as an example to verify the validity of the optimization model. The valuable results provide important reference for engineers to enhance thermal design technology of antennas.

Phased array UT (Ultrasonic Testing) used in electricity production plants

International Nuclear Information System (INIS)

Kodaira, Takeshi

2012-01-01

Phased Array-Ultrasonic testing techniques widely used for detection and quantitative determination of the lattice defects which have been formed from fatigues or stress corrosion cracking in the materials used in the electricity production plants are presented with particular focus on the accurate determination of the defects depth (sizing) and defects discrimination applicable to weld metals of austenite stainless steels and Ni base alloys. The principle of this non-destructive analysis is briefly explained, followed by point and matrix focus phased array methods developed by Mitsubishi Heavy Industries, Ltd are explained rather in detail with illustration and the evaluated results. (S. Ohno)

Amplitude and Phase Calibration of an Dual Polarized Active Phased Array Antenna

NARCIS (Netherlands)

Vermeulen, B.C.B.; Paquay, M.H.A.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

1996-01-01

In the Netherlands, a Polarimetrie C-band aircraft SAR (Synthetic Aperture Radar) has been developed. The project is called PHARUS, an acronym for Phased Array Universal SAR. This instrument serves remote sensing applications. The antenna system contains 48 modules (expandable to 96). A module is

A study on the crack inspection signal characteristics for power plant components by phased array UT

International Nuclear Information System (INIS)

Cho, Yong Sang; Lim, Sang Gyu; Kil, Du Song

2001-01-01

Phased array ultrasonic testing system has become available for practical application in complicated geometry such as turbine blade root, tenon, disc in power industry. This research describes the characteristics of phased array UT signal for various type of blade roots in thermal Power Plant turbines. This application of Phased array ultrasonic testing system has been promoted mainly to save inspection time and labor cost of turbine inspection. The characteristic of phase array UT signal for power plant component is very simple to understand but to difficult for perform the inspection. Since our sophisticated inspection technique and systems are essential for the inspection of steam turbine blade roots that require high reliability, we intend to develop new technology and improve phased array technique based on the wide and much experience for the inspection of turbine components.

Optical Techniques for Millimeter-Wave Phased Array Communications Antennas

National Research Council Canada - National Science Library

Edge, Colin

1998-01-01

The scope of this program was to study the application of optical techniques to signal distribution and beamforming networks in phased array antennas for Army mobile tactical communications systems...

Development of a Fibre-Phased Array Laser-EMAT Ultrasonic System for Defect Inspection

International Nuclear Information System (INIS)

Pei, C; Demachi, K; Koyama, K; Uesaka, M; Fukuchi, T; Chen, Z

2014-01-01

In this work, a phased array laser ultrasound system with using fibre optic delivery and a custom-designed focusing objective lens has been developed for enhancing the ultrasound generation. The fibre-phased array method is applied to improve the sensitivity and detecting ability of the laser-EMAT system for defect inspection

Multiple wall-reflection effect in adaptive-array differential-phase reflectometry on QUEST

International Nuclear Information System (INIS)

Idei, H.; Fujisawa, A.; Nagashima, Y.; Onchi, T.; Hanada, K.; Zushi, H.; Mishra, K.; Hamasaki, M.; Hayashi, Y.; Yamamoto, M.K.

2016-01-01

A phased array antenna and Software-Defined Radio (SDR) heterodyne-detection systems have been developed for adaptive array approaches in reflectometry on the QUEST. In the QUEST device considered as a large oversized cavity, standing wave (multiple wall-reflection) effect was significantly observed with distorted amplitude and phase evolution even if the adaptive array analyses were applied. The distorted fields were analyzed by Fast Fourier Transform (FFT) in wavenumber domain to treat separately the components with and without wall reflections. The differential phase evolution was properly obtained from the distorted field evolution by the FFT procedures. A frequency derivative method has been proposed to overcome the multiple-wall reflection effect, and SDR super-heterodyned components with small frequency difference for the derivative method were correctly obtained using the FFT analysis

Inspection of austenitic welds with ultrasonic phased array technology

Energy Technology Data Exchange (ETDEWEB)

Garcia, A.; Fernandez, F. [Tecnatom (Spain); Dutruc, R.; Ferriere, R. [Metalscan (France)

2011-07-01

This series of slides presents the use of ultrasonic phased array technology in the inspection of austenitic welds. The inspection from outside surface (the inspection is performed in contact using wedges to couple the probe to the outer surface of the component) shows that longitudinal wave is the most adequate for perpendicular scans and transversal ultrasonic wave is the most adequate for parallel scans. Detection and length sizing are performed optimally in perpendicular scans. The inspection from inside surface shows: -) Good results in the detection of defects (Sizing has met the requirements imposed by the Authority of the Russian Federation); -) The new design of the mechanical equipment and of the numerous ultrasonic beams refracted by the array probes has increased the volume inspected. The design of the mechanical equipment has also allowed new areas to be inspected (example a piping weld that was not accessible from the outer surface; -) The ultrasonic procedure and Inspection System developed have been validated by the Authority of the Russian Federation. Phase array technique supplies solutions to solve accessibility concerns and improve the ultrasonic inspections of nuclear components

A Multi-Band Photonic Phased Array Antenna for High-Data Rate Communication, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Multi-band phased array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. In order to steer...

A Multi-band Photonic Phased Array Antenna for High-Date Rate Communication, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Multi-band phased array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. In order to steer...

Phased arrays: A strategy to lower the energy threshold for neutrinos

Directory of Open Access Journals (Sweden)

Wissel Stephanie

2017-01-01

Full Text Available In-ice radio arrays are optimized for detecting the highest energy, cosmogenic neutrinos expected to be produced though cosmic ray interactions with background photons. However, there are two expected populations of high energy neutrinos: the astrophysical flux observed by IceCube (~1 PeV and the cosmogenic flux (~ 1017 eV or 100 PeV. Typical radio arrays employ a noise-riding trigger, which limits their minimum energy threshold based on the background noise temperature of the ice. Phased radio arrays could lower the energy threshold by combining the signals from several channels before triggering, thereby improving the signal-to-noise at the trigger level. Reducing the energy threshold would allow radio experiments to more efficiently overlap with optical Cherenkov neutrino telescopes as well as for more efficient searches for cosmogenic neutrinos. We discuss the proposed technique and prototypical phased arrays deployed in an anechoic chamber and at Greenland’s Summit Station.

Jammed-array wideband sawtooth filter.

Science.gov (United States)

Tan, Zhongwei; Wang, Chao; Goda, Keisuke; Malik, Omer; Jalali, Bahram

2011-11-21

We present an all-optical passive low-cost spectral filter that exhibits a high-resolution periodic sawtooth spectral pattern without the need for active optoelectronic components. The principle of the filter is the partial masking of a phased array of virtual light sources with multiply jammed diffraction orders. We utilize the filter's periodic linear map between frequency and intensity to demonstrate fast sensitive interrogation of fiber Bragg grating sensor arrays and ultrahigh-frequency electrical sawtooth waveform generation. © 2011 Optical Society of America

Magnetic Flux Distribution of Linear Machines with Novel Three-Dimensional Hybrid Magnet Arrays

Directory of Open Access Journals (Sweden)

Nan Yao

2017-11-01

Full Text Available The objective of this paper is to propose a novel tubular linear machine with hybrid permanent magnet arrays and multiple movers, which could be employed for either actuation or sensing technology. The hybrid magnet array produces flux distribution on both sides of windings, and thus helps to increase the signal strength in the windings. The multiple movers are important for airspace technology, because they can improve the system’s redundancy and reliability. The proposed design concept is presented, and the governing equations are obtained based on source free property and Maxwell equations. The magnetic field distribution in the linear machine is thus analytically formulated by using Bessel functions and harmonic expansion of magnetization vector. Numerical simulation is then conducted to validate the analytical solutions of the magnetic flux field. It is proved that the analytical model agrees with the numerical results well. Therefore, it can be utilized for the formulation of signal or force output subsequently, depending on its particular implementation.

Adaptive phase measurements in linear optical quantum computation

International Nuclear Information System (INIS)

Ralph, T C; Lund, A P; Wiseman, H M

2005-01-01

Photon counting induces an effective non-linear optical phase shift in certain states derived by linear optics from single photons. Although this non-linearity is non-deterministic, it is sufficient in principle to allow scalable linear optics quantum computation (LOQC). The most obvious way to encode a qubit optically is as a superposition of the vacuum and a single photon in one mode-so-called 'single-rail' logic. Until now this approach was thought to be prohibitively expensive (in resources) compared to 'dual-rail' logic where a qubit is stored by a photon across two modes. Here we attack this problem with real-time feedback control, which can realize a quantum-limited phase measurement on a single mode, as has been recently demonstrated experimentally. We show that with this added measurement resource, the resource requirements for single-rail LOQC are not substantially different from those of dual-rail LOQC. In particular, with adaptive phase measurements an arbitrary qubit state α vertical bar 0>+β vertical bar 1> can be prepared deterministically

Passive longitudinal phase space linearizer

Directory of Open Access Journals (Sweden)

P. Craievich

2010-03-01

Full Text Available We report on the possibility to passively linearize the bunch compression process in electron linacs for the next generation x-ray free electron lasers. This can be done by using the monopole wakefields in a dielectric-lined waveguide. The optimum longitudinal voltage loss over the length of the bunch is calculated in order to compensate both the second-order rf time curvature and the second-order momentum compaction terms. Thus, the longitudinal phase space after the compression process is linearized up to a fourth-order term introduced by the convolution between the bunch and the monopole wake function.

Three-dimensional real-time synthetic aperture imaging using a rotating phased array transducer

DEFF Research Database (Denmark)

Nikolov, Svetoslav; Dufait, Remi; Schoisswohl, Armin

2002-01-01

phased array, which is rotated over the volume of interest. The data is acquired using coded signals and synthetic transmit aperture imaging. Only one group of elements transmits at a time. The delays are set such as to form a cylindrical wave. The back-scattered signal carries information not only from......Current 3D real-time imaging is done either with sparse 2D arrays, or with mechanically moved phased arrays. The former results in a poor resolution and contrast due to a limited amount of elements. The latter has the disadvantage of low frame rates due to the sequential acquisition of the volume...... line-by-line and plane-by-plane. This paper describes an approach which combines mechanically moved phased array with synthetic transmit aperture imaging, resulting in high volume acquisition rates without a trade-off in image quality. The scan method uses a conventional fully populated 64 element...

Three-dimensional optoacoustic tomography using a conventional ultrasound linear detector array: whole-body tomographic system for small animals.

Science.gov (United States)

Gateau, Jerome; Caballero, Miguel Angel Araque; Dima, Alexander; Ntziachristos, Vasilis

2013-01-01

Optoacoustic imaging relies on the detection of ultrasonic waves induced by laser pulse excitations to map optical absorption in biological tissue. A tomographic geometry employing a conventional ultrasound linear detector array for volumetric optoacoustic imaging is reported. The geometry is based on a translate-rotate scanning motion of the detector array, and capitalizes on the geometrical characteristics of the transducer assembly to provide a large solid angular detection aperture. A system for three-dimensional whole-body optoacoustic tomography of small animals is implemented. The detection geometry was tested using a 128-element linear array (5.0∕7.0 MHz, Acuson L7, Siemens), moved by steps with a rotation∕translation stage assembly. Translation and rotation range of 13.5 mm and 180°, respectively, were implemented. Optoacoustic emissions were induced in tissue-mimicking phantoms and ex vivo mice using a pulsed laser operating in the near-IR spectral range at 760 nm. Volumetric images were formed using a filtered backprojection algorithm. The resolution of the optoacoustic tomography system was measured to be better than 130 μm in-plane and 330 μm in elevation (full width half maximum), and to be homogenous along a 15 mm diameter cross section due to the translate-rotate scanning geometry. Whole-body volumetric optoacoustic images of mice were performed ex vivo, and imaged organs and blood vessels through the intact abdominal and head regions were correlated to the mouse anatomy. Overall, the feasibility of three-dimensional and high-resolution whole-body optoacoustic imaging of small animal using a conventional linear array was demonstrated. Furthermore, the scanning geometry may be used for other linear arrays and is therefore expected to be of great interest for optoacoustic tomography at macroscopic and mesoscopic scale. Specifically, conventional detector arrays with higher central frequencies may be investigated.

Sampling phased array - a new technique for ultrasonic signal processing and imaging

OpenAIRE

Verkooijen, J.; Boulavinov, A.

2008-01-01

Over the past 10 years, the improvement in the field of microelectronics and computer engineering has led to significant advances in ultrasonic signal processing and image construction techniques that are currently being applied to non-destructive material evaluation. A new phased array technique, called 'Sampling Phased Array', has been developed in the Fraunhofer Institute for Non-Destructive Testing([1]). It realises a unique approach of measurement and processing of ultrasonic signals. Th...

Ultrasonic phased arrays for nondestructive inspection of forgings

International Nuclear Information System (INIS)

Wuestenberg, H.; Rotter, B.; Klanke, H.P.; Harbecke, D.

1993-01-01

Ultrasonic examinations on large forgings like rotor shafts for turbines or components for nuclear reactors are carried out at various manufacturing stages and during in-service inspections. During the manufacture, most of the inspections are carried out manually. Special in-service conditions, such as those at nuclear pressure vessels, have resulted in the development of mechanized scanning equipment. Ultrasonic probes have improved, and well-adapted sound fields and pulse shapes and based on special imaging procedures for the representation of the reportable reflectors have been applied. Since the geometry of many forgings requires the use of a multitude of angles for the inspections in-service and during manufacture, phased-array probes can be used successfully. The main advantages of the phased-array concept, e.g. the generation of a multitude of angles with the typical increase of redundancy in detection and quantitative evaluation and the possibility to produce pictures of defect situations, will be described in this contribution

Kalman filter-based tracking of moving objects using linear ultrasonic sensor array for road vehicles

Science.gov (United States)

Li, Shengbo Eben; Li, Guofa; Yu, Jiaying; Liu, Chang; Cheng, Bo; Wang, Jianqiang; Li, Keqiang

2018-01-01

Detection and tracking of objects in the side-near-field has attracted much attention for the development of advanced driver assistance systems. This paper presents a cost-effective approach to track moving objects around vehicles using linearly arrayed ultrasonic sensors. To understand the detection characteristics of a single sensor, an empirical detection model was developed considering the shapes and surface materials of various detected objects. Eight sensors were arrayed linearly to expand the detection range for further application in traffic environment recognition. Two types of tracking algorithms, including an Extended Kalman filter (EKF) and an Unscented Kalman filter (UKF), for the sensor array were designed for dynamic object tracking. The ultrasonic sensor array was designed to have two types of fire sequences: mutual firing or serial firing. The effectiveness of the designed algorithms were verified in two typical driving scenarios: passing intersections with traffic sign poles or street lights, and overtaking another vehicle. Experimental results showed that both EKF and UKF had more precise tracking position and smaller RMSE (root mean square error) than a traditional triangular positioning method. The effectiveness also encourages the application of cost-effective ultrasonic sensors in the near-field environment perception in autonomous driving systems.

SAR processing with stepped chirps and phased array antennas.

Energy Technology Data Exchange (ETDEWEB)

Doerry, Armin Walter

2006-09-01

Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

New customizable phased array UT instrument opens door for furthering research and better industrial implementation

International Nuclear Information System (INIS)

Dao, Gavin; Ginzel, Robert

2014-01-01

Phased array UT as an inspection technique in itself continues to gain wide acceptance. However, there is much room for improvement in terms of implementation of Phased Array (PA) technology for every unique NDT application across several industries (e.g. oil and petroleum, nuclear and power generation, steel manufacturing, etc.). Having full control of the phased array instrument and customizing a software solution is necessary for more seamless and efficient inspections, from setting the PA parameters, collecting data and reporting, to the final analysis. NDT researchers and academics also need a flexible and open platform to be able to control various aspects of the phased array process. A high performance instrument with advanced PA features, faster data rates, a smaller form factor, and capability to adapt to specific applications, will be discussed

A 128 pixel linear array for radiotherapy quality assurance

Energy Technology Data Exchange (ETDEWEB)

Franco, L. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Gomez, F. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain)]. E-mail: faustgr@usc.es; Iglesias, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Lobato, R. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Marin, J. [CIEMAT, Laboratorio de Electronica y Automatica, 28040 Madrid Spain (Spain); Mosquera, J. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Pardo, J. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain)]. E-mail: juanpm@usc.es; Pazos, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Pena, J. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Pombar, M. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Rodriguez, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Saavedra, D. [Universidade da Coruna, Dpto. de Enxeneria Industrial II, 15403 Ferrol Spain (Spain); Sendon, J. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Yanez, A. [Universidade da Coruna, Dpto. de Enxeneria Industrial II, 15403 Ferrol Spain (Spain)

2004-12-11

New radiotherapy techniques require detectors able to verify and monitor the clinical beam with high spatial resolution and fast response. Room temperature organic liquid ionization detectors are becoming an alternative to standard air ionization chambers, due to their tissue equivalent behavior, their sensibility and small directional dependence. A liquid isooctane filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7mmx1.7mm and a gap of 0.5mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy. The gap and the polarization voltage have been chosen in order to guarantee a linear relationship between the dose rate and the readout signal at high dose rates. As readout electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC.In the first device tests we have confirmed linearity up to a 6.7Gy/min dose rate with a deviation less than 1%. A profile with a signal-to-noise ratio around 500 can be obtained for a 4Gy/min dose rate with a 10 ms integration time.

A 128 pixel linear array for radiotherapy quality assurance

International Nuclear Information System (INIS)

Franco, L.; Gomez, F.; Iglesias, A.; Lobato, R.; Marin, J.; Mosquera, J.; Pardo, J.; Pazos, A.; Pena, J.; Pombar, M.; Rodriguez, A.; Saavedra, D.; Sendon, J.; Yanez, A.

2004-01-01

New radiotherapy techniques require detectors able to verify and monitor the clinical beam with high spatial resolution and fast response. Room temperature organic liquid ionization detectors are becoming an alternative to standard air ionization chambers, due to their tissue equivalent behavior, their sensibility and small directional dependence. A liquid isooctane filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7mmx1.7mm and a gap of 0.5mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy. The gap and the polarization voltage have been chosen in order to guarantee a linear relationship between the dose rate and the readout signal at high dose rates. As readout electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC.In the first device tests we have confirmed linearity up to a 6.7Gy/min dose rate with a deviation less than 1%. A profile with a signal-to-noise ratio around 500 can be obtained for a 4Gy/min dose rate with a 10 ms integration time

Slow and fast light in SOA-EA structures for phased-array antennas

DEFF Research Database (Denmark)

Sales, S.; Öhman, Filip; Bermejo, A.

We present an SOA-EA structure for controlling the phase and amplitude of optically fed phased-array antennas. Phase shifts of 40 degrees are obtained through slow and fast light effects by changing only the reverse voltage....

A contribution to phased array ultrasonic inspection of welds: defect patterns and sizing capability

Energy Technology Data Exchange (ETDEWEB)

Ciorau, P., E-mail: peter.ciorau@opg.com [Ontario Power Generation Inc., Inspection, Maintenance and Commercial Services, Tiverton, Ontario (Canada)

2008-07-01

The paper presents defect patterns for weld inspection detected with phased array ultrasonic technology (PAUT). The sizing capability for length, height, outer and inner ligament for specific implanted weld defects in training samples and mock-ups with thickness between 6.4-52 mm. It is discussed the influence of beam angle on sizing the lack of fusion defect. More than 50 implanted weld defects with 70% crack population were sized using high-frequency (5-10 MHz) linear array probes. The correlation between the design/manufacturer flaw size and PAUT data for length, height and ligament is graphically presented. It was concluded the length is oversized by 2-6 mm, height and inner ligament are undersized by 0.2 to 0.5 mm, and outer ligament is oversized by 0.5 mm. The sizing results were based on non-amplitude techniques and pattern display of S- and B-scan. The sizing capability is far better than ASME XI tolerances for performance demonstration and comparable to time of flight diffraction (TOFD) ideal tolerances. (author)

A contribution to phased array ultrasonic inspection of welds: defect patterns and sizing capability

International Nuclear Information System (INIS)

Ciorau, P.

2008-01-01

The paper presents defect patterns for weld inspection detected with phased array ultrasonic technology (PAUT). The sizing capability for length, height, outer and inner ligament for specific implanted weld defects in training samples and mock-ups with thickness between 6.4-52 mm. It is discussed the influence of beam angle on sizing the lack of fusion defect. More than 50 implanted weld defects with 70% crack population were sized using high-frequency (5-10 MHz) linear array probes. The correlation between the design/manufacturer flaw size and PAUT data for length, height and ligament is graphically presented. It was concluded the length is oversized by 2-6 mm, height and inner ligament are undersized by 0.2 to 0.5 mm, and outer ligament is oversized by 0.5 mm. The sizing results were based on non-amplitude techniques and pattern display of S- and B-scan. The sizing capability is far better than ASME XI tolerances for performance demonstration and comparable to time of flight diffraction (TOFD) ideal tolerances. (author)

A CMOS 128-APS linear array integrated with a LVOF for highsensitivity and high-resolution micro-spectrophotometry

NARCIS (Netherlands)

Liu, C.; Emadi, A.; Wu, H.; De Graaf, G.; Wolffenbuttel, R.F.

2010-01-01

A linear array of 128 Active Pixel Sensors has been developed in standard CMOS technology and a Linear Variable Optical Filter (LVOF) is added using CMOS-compatible post-process, resulting in a single chip highly-integrated highresolution microspectrometer. The optical requirements imposed by the

Three-dimensionally Functionalized Reverse Phase Glycoprotein Array for Cancer Biomarker Discovery and Validation

OpenAIRE

Pan, Li; Aguilar, Hillary Andaluz; Wang, Linna; Iliuk, Anton; Tao, W. Andy

2016-01-01

Glycoproteins have vast structural diversity which plays an important role in many biological processes and have great potential as disease biomarkers. Here we report a novel functionalized reverse phase protein array (RPPA), termed polymer-based reverse phase GlycoProtein Array (polyGPA), to specifically capture and profile glycoproteomes, and validate glycoproteins. Nitrocellulose membrane functionalized with globular hydroxyaminodendrimers was used to covalently capture pre-oxidized glycan...

Multiband Photonic Phased-Array Antenna

Science.gov (United States)

Tang, Suning

2015-01-01

A multiband phased-array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. Crystal Research, Inc., has developed a multiband photonic antenna that is based on a high-speed, optical, true-time-delay beamformer. It is capable of simultaneously steering multiple independent radio frequency (RF) beams in less than 1,000 nanoseconds. This high steering speed is 3 orders of magnitude faster than any existing optical beamformer. Unlike other approaches, this technology uses a single controlling device per operation band, eliminating the need for massive optical switches, laser diodes, and fiber Bragg gratings. More importantly, only one beamformer is needed for all antenna elements.

Linear and nonlinear excitations in two stacks of parallel arrays of long Josephson junctions

DEFF Research Database (Denmark)

Carapella, G.; Constabile, Giovanni; Latempa, R.

2000-01-01

We investigate a structure consisting of two parallel arrays of long Josephson junctions sharing a common electrode that allows inductive coupling between the arrays. A model for this structure is derived starting from the description of its continuous limit. The excitation of linear cavity modes...... known from continuous and discrete systems as well as the excitation of a new state exhibiting synchronization in two dimensions are inferred from the mathematical model of the system. The stable nonlinear solution of the coupled sine-Gordon equations describing the system is found to consist...

Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

Science.gov (United States)

Oeftering, Richard C.

1999-01-01

High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

Ultraino: An Open Phased-Array System for Narrowband Airborne Ultrasound Transmission.

Science.gov (United States)

Marzo, Asier; Corkett, Tom; Drinkwater, Bruce W

2018-01-01

Modern ultrasonic phased-array controllers are electronic systems capable of delaying the transmitted or received signals of multiple transducers. Configurable transmit-receive array systems, capable of electronic steering and shaping of the beam in near real-time, are available commercially, for example, for medical imaging. However, emerging applications, such as ultrasonic haptics, parametric audio, or ultrasonic levitation, require only a small subset of the capabilities provided by the existing controllers. To meet this need, we present Ultraino, a modular, inexpensive, and open platform that provides hardware, software, and example applications specifically aimed at controlling the transmission of narrowband airborne ultrasound. Our system is composed of software, driver boards, and arrays that enable users to quickly and efficiently perform research in various emerging applications. The software can be used to define array geometries, simulate the acoustic field in real time, and control the connected driver boards. The driver board design is based on an Arduino Mega and can control 64 channels with a square wave of up to 17 Vpp and /5 phase resolution. Multiple boards can be chained together to increase the number of channels. The 40-kHz arrays with flat and spherical geometries are demonstrated for parametric audio generation, acoustic levitation, and haptic feedback.

A Centerless Circular Array Method: Extracting Maximal Information on Phase Velocities of Rayleigh Waves From Microtremor Records From a Simple Seismic Array

Science.gov (United States)

Cho, I.; Tada, T.; Shinozaki, Y.

2005-12-01

We have developed a Centerless Circular Array (CCA) method of microtremor exploration, an algorithm that enables to estimate phase velocities of Rayleigh waves by analyzing vertical-component records of microtremors that are obtained with an array of three or five seismic sensors placed around a circumference. Our CCA method shows a remarkably high performance in long-wavelength ranges because, unlike the frequency-wavenumber spectral method, our method does not resolve individual plane-wave components in the process of identifying phase velocities. Theoretical considerations predict that the resolving power of our CCA method in long-wavelength ranges depends upon the SN ratio, or the ratio of power of the propagating components to that of the non-propagating components (incoherent noise) contained in the records from the seismic array. The applicability of our CCA method to small-sized arrays on the order of several meters in radius has already been confirmed in our earlier work (Cho et al., 2004). We have deployed circular seismic arrays of different sizes at test sites in Japan where the underground structure is well documented through geophysical exploration, and have applied our CCA method to microtremor records to estimate phase velocities of Rayleigh waves. The estimates were then checked against "model" phase velocities that are derived from theoretical calculations. For arrays of 5, 25, 300 and 600 meters in radii, the estimated and model phase velocities demonstrated fine agreement within a broad wavelength range extending from a little larger than 3r (r: the array radius) up to at least 40r, 14r, 42r and 9r, respectively. This demonstrates the applicability of our CCA method to arrays on the order of several to several hundreds of meters in radii, and also illustrates, in a typical way, the markedly high performance of our CCA method in long-wavelength ranges. We have also invented a mathematical model that enables to evaluate the SN ratio in a given

Development of phased array UT technique for inspection of turbine wheel rim

International Nuclear Information System (INIS)

Komura, I.; Nagal, S.; Goto, M.; Ohmatsu, K.

1986-01-01

A phased array UT technique has been developed for the improvement of defect detection under the keyway region of shrunk-on type turbine wheel. The sector scanning mode operation with plexiglas wedge of phased array capability was applied to construct the B-scope image of turbine wheel rim region. Preceding to the inspection test of the model specimen having real shape of rim region, the distribution of sound field intensity along the steering angle of the scanning line was measured on the test block. Then, the minimum depth of detectable defect by the B-scope imaging was evaluated on the dovetail shape specimens which had different depth EDM notches at the each hook fillet. As the results, it has been realized that the B-scope imaging of the sector scanning mode phased array technique has a capability for distinguishing the defect echoes from the many reflection echoes caused by the complexed shape of wheel rim region

Ultrasound beam characteristics of a symmetric nodal origami based array

Science.gov (United States)

Bilgunde, Prathamesh N.; Bond, Leonard J.

2018-04-01

Origami-the ancient art of paper folding-is being explored in acoustics for effective focusing of sound. In this short communication, we present a numerical investigation of beam characteristics for an origami based ultrasound array. A spatial re-configuration of array elements is performed based upon the symmetric nodal origami. The effect of fold angle on the ultrasound beam is evaluated using frequency domain and transient finite element analysis. It was found that increase in the fold angle reduces near field length by 58% and also doubles the beam intensity as compared to the linear array. Transient analysis also indicated 80% reduction in the -6dB beam width, which can improve the lateral resolution of phased array. Such a spatially re-configurable array could potentially be used in the future to reduce the cost of electronics in the phased array instrumentation.

Ultrasound pulse-echo measurements on rough surfaces with linear array transducers

DEFF Research Database (Denmark)

Sjøj, Sidsel M. N.; Blanco, Esther N.; Wilhjelm, Jens E.

2012-01-01

The echo from planar surfaces with rms roughness, Rq, in the range from 0-155 μm was measured with a clinical linear array transducer at different angles of incidence at 6 MHz and 12 MHz. The echo-pulse from the surfaces was isolated with an equal sized window and the power of the echo-pulse was ......The echo from planar surfaces with rms roughness, Rq, in the range from 0-155 μm was measured with a clinical linear array transducer at different angles of incidence at 6 MHz and 12 MHz. The echo-pulse from the surfaces was isolated with an equal sized window and the power of the echo......-pulse was calculated. The power of the echo from the smooth surface (Rq = 0) is highly angle-dependent due to a high degree of specular reflection. Within the angular range considered here, -10° to 10°, the variation spans a range of 18 dB at both 6 MHz and 12 MHz. When roughness increases, the angle......-dependence decreases, as the echo process gradually changes from pure reflection to being predominantly governed by backscattering. The power of the echoes from the two roughest surfaces (Rq = 115 μm and 155 μm) are largely independent of angle at both 6 MHz and 12 MHz with a variation of 2 dB in the angular range...

Study on the near-field non-linearity (SMILE) of high power diode laser arrays

Science.gov (United States)

Zhang, Hongyou; Jia, Yangtao; Li, Changxuan; Zah, Chung-en; Liu, Xingsheng

2018-02-01

High power laser diodes have been found a wide range of industrial, space, medical applications, characterized by high conversion efficiency, small size, light weight and a long lifetime. However, due to thermal induced stress, each emitter in a semiconductor laser bar or array is displaced along p-n junction, resulting of each emitter is not in a line, called Near-field Non-linearity. Near-field Non-linearity along laser bar (also known as "SMILE") determines the outcome of optical coupling and beam shaping [1]. The SMILE of a laser array is the main obstacle to obtain good optical coupling efficiency and beam shaping from a laser array. Larger SMILE value causes a larger divergence angle and a wider line after collimation and focusing, respectively. In this letter, we simulate two different package structures based on MCC (Micro Channel Cooler) with Indium and AuSn solders, including the distribution of normal stress and the SMILE value. According to the theoretical results, we found the distribution of normal stress on laser bar shows the largest in the middle and drops rapidly near both ends. At last, we did another experiment to prove that the SMILE value of a laser bar was mainly affected by the die bonding process, rather than the operating condition.

Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array

Directory of Open Access Journals (Sweden)

K. N. Abdul Rani

2012-09-01

Full Text Available In this paper, we proposed a newly modified cuckoo search (MCS algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL and/or nulls control. The basic cuckoo search (CS algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA techniques include particle swarm optimization (PSO and genetic algorithms (GA.

Visualization and quantitative research of stress corrosion cracking using the three-dimensional phased array ultrasonic technique

International Nuclear Information System (INIS)

Kitazawa, So; Kono, Naoyuki; Kudo, Takeshi; Isaka, Katsumi

2013-01-01

The three-dimensional phased-array (3D-PA) ultrasonic technique has been applied to a stress corrosion cracking (SCC) in base metal, and its results for sizing have been quantitatively evaluated. The 3D-PA allows operators to scan objects volumetrically and to display results as 3D images facilitating evaluation processes considerably. The scanning pattern used is called the moving rotational sectorial-scan (MRS-scan) and it is composed of many sectors of different azimuth angles as moving the probe linearly. The MRS-scan significantly improves the inspection of flaws without skillful searching motion of the probe, because the flaws are stereoscopically insonified by a number of ultrasonic beams coming from various directions. The SCC was evaluated by the MRS-scan with a matrix array probe. Not only the deepest tip but also all parts of the crack were able to be successfully visualized and sized with an accuracy of the root mean square error of 0.9 mm. (author)

Application of the ultrasonic phased array technique to alloy 182 weld inspection in PWR

International Nuclear Information System (INIS)

Hsiao, Chu Chung; Shie, Namg Chian; Chu, Shyr Liang; Lee, Sou See; Toung, Jean Chung; Su, Liang Chun; Yang, Hai Ming

2006-01-01

Cracks were found in nickel-based welds frequently in some nuclear power plants. The development of inspection technique capability of finding these cracks is thus in great demand. The difficulties of inspection and evaluation for nickel-based welds include ultrasonic reflection of interface of dissimilar materials, ultrasonic distortion of anisotropic microstructure, and signal-to-noise ratio reduction of coarse grain. In this study, an Alloy 182 mock-up with the same size and material properties as in the field is designed and fabricated. The Alloy 182 mock-up specimen contains various cracks and notches for calibration. Phased array UT and other ultrasonic inspection techniques are used in this study. Based on the experiment results, the phased array probe with 2D dual crystals and low frequency (1.5MHz) longitudinal wave is found to perform well. Finally, phased array ultrasonic testing technique has been approved to be an effectively nondestructive test method for DMW with real size testing block involved. Typically, phased array probe can generate sharp tip diffraction signal and thus reliable and accurate result can be obtained for sizing the defect. Furthermore, phased array probe can also generate various angles and focal lengths and thus combinatorial effect can be achieved for several traditional probes. With a full understanding of the beam behavior and an optimized delay laws, the phased away ultrasonic technique integrated with an automatic scanner will achieve not only to save scanning time but also to reduce the amount of radiation exposure on field inspection.

Phase and amplitude detection system for the Stanford Linear Accelerator

International Nuclear Information System (INIS)

Fox, J.D.; Schwarz, H.D.

1983-01-01

A computer controlled phase and amplitude detection system to measure and stabilize the rf power sources in the Stanford Linear Accelerator is described. This system measures the instantaneous phase and amplitude of a 1 microsecond 2856 MHz rf pulse and will be used for phase feedback control and for amplitude and phase jitter detection. This paper discusses the measurement system performance requirements for the operation of the Stanford Linear Collider, and the design and implementation of the phase and amplitude detection system. The fundamental software algorithms used in the measurement are described, as is the performance of the prototype phase and amplitude detector system

Development and implementation of UT procedures for nuclear and other applications using TRL phased array probes

International Nuclear Information System (INIS)

Chardome, V.; Delaide, M.; Cermak, J.; Cruysweegs, E.; Plateau, M.

2006-01-01

In the past, Vincotte developed, qualified and applied various UT procedures for the automated in-service inspection of austenitic and dissimilar metal welds, using conventional ultrasonic probes. In a process of continuous improvement, Vincotte is upgrading these existing procedures by applying low frequency TRL phased array probes. This presentation situates this recent innovation within the phased array history of Vincotte. Particular attention will be paid to these newest phased array developments, in terms of probe development, angled beam generation and scanning patterns. (orig.)

Reconfigurable Transmission Line for a Series-Fed Ku-Band Phased Array Using a Single Feed

Science.gov (United States)

Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda. Felix, A.

2013-01-01

The paper presents a novel approach to realize a lowcost phased array using a simple feeding mechanism. Specifically, a single coplanar stripline (CPS) transmission line is used to feed the antenna array elements. By controlling the CPS's dielectric properties using a movable dielectric plunger, scanning is achieved. Due to its simplicity, single feed, and no phase shifters, this approach leads to a dramatic reduction in cost which does not scale for larger arrays.

The utility of sparse 2D fully electronically steerable focused ultrasound phased arrays for thermal surgery: a simulation study

International Nuclear Information System (INIS)

Ellens, Nicholas; Pulkkinen, Aki; Song Junho; Hynynen, Kullervo

2011-01-01

Sparse arrays are widely used in diagnostic ultrasound for their strong performance and relative technical simplicity. This simulation study assessed the efficacy of phased arrays of varied sparseness for thermal surgery, especially with regard to power consumption and near-field heating. It employs a linear ultrasound propagation model and a semi-analytical solution to the Pennes' bioheat transfer equation. The basic design had 4912 cylindrical transducers (500 kHz) arranged on a flat 12 cm disk (1.5 mm spacing). This array was compared to randomly-thinned sparse arrays with 75%, 50% and 25% populations. Temperature elevations of 60 and 70 deg. C were induced in sonication times of 5-20 s, at foci spanning depths of 50-150 mm and radii of 0-60 mm. The sparse arrays produced nearly indistinguishable focal patterns but, averaged across the foci, required 132%, 200% and 393% of the power of the full array, respectively, applied through fewer transducer elements. Comparable results were found at 1 MHz from equivalent arrays. Simulated lesions were formed (thermal dose ≥ 240 equivalent minutes at 43 deg. C (T 43 )) and 'transition' and 'unsafe' regions (both defined as 5 min 43 < 240 min) were identified, the former immediately surrounding the lesion and the latter anywhere else. At a depth of 100 mm, sparse arrays were found to produce comparable lesions to the full array at the focus, but 'unsafe', over-heated near-field regions after some ablated lesion volume: about 12 mL for the 25% array, around 100 mL for the 50% array, while the 75% and full arrays produced 150 mL lesions safely.

Mixed Linear/Square-Root Encoded Single Slope Ramp Provides a Fast, Low Noise Analog to Digital Converter with Very High Linearity for Focal Plane Arrays

Science.gov (United States)

Wrigley, Christopher James (Inventor); Hancock, Bruce R. (Inventor); Newton, Kenneth W. (Inventor); Cunningham, Thomas J. (Inventor)

2014-01-01

An analog-to-digital converter (ADC) converts pixel voltages from a CMOS image into a digital output. A voltage ramp generator generates a voltage ramp that has a linear first portion and a non-linear second portion. A digital output generator generates a digital output based on the voltage ramp, the pixel voltages, and comparator output from an array of comparators that compare the voltage ramp to the pixel voltages. A return lookup table linearizes the digital output values.

An Optimal Beamforming Algorithm for Phased-Array Antennas Used in Multi-Beam Spaceborne Radiometers

DEFF Research Database (Denmark)

Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.

2015-01-01

Strict requirements for future spaceborne ocean missions using multi-beam radiometers call for new antenna technologies, such as digital beamforming phased arrays. In this paper, we present an optimal beamforming algorithm for phased-array antenna systems designed to operate as focal plane arrays...... to a FPA feeding a torus reflector antenna (designed under the contract with the European Space Agency) and tested for multiple beams. The results demonstrate an improved performance in terms of the optimized beam characteristics, yielding much higher spatial and radiometric resolution as well as much...

Improving emission uniformity and linearizing band dispersion in nanowire arrays using quasi-aperiodicity

Energy Technology Data Exchange (ETDEWEB)

Anderson, P. Duke [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Univ. of Southern California, Los Angeles, CA (United States). Ming Hsieh Dept. of Electrical Engineering; Koleske, Daniel D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Povinelli, Michelle L. [Univ. of Southern California, Los Angeles, CA (United States). Ming Hsieh Dept. of Electrical Engineering; Subramania, Ganapathi [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2017-10-01

For this study, we experimentally investigate a new class of quasi-aperiodic structures for improving the emission pattern in nanowire arrays. Efficient normal emission, as well as lasing, can be obtained from III-nitride photonic crystal (PhC) nanowire arrays that utilize slow group velocity modes near the Γ-point in reciprocal space. However, due to symmetry considerations, the emitted far-field pattern of such modes are often ‘donut’-like. Many applications, including lighting for displays or lasers, require a more uniform beam profile in the far-field. Previous work has improved far-field beam uniformity of uncoupled modes by changing the shape of the emitting structure. However, in nanowire systems, the shape of nanowires cannot always be arbitrarily changed due to growth or etch considerations. Here, we investigate breaking symmetry by instead changing the position of emitters. Using a quasi-aperiodic geometry, which changes the emitter position within a photonic crystal supercell (2x2), we are able to linearize the photonic bandstructure near the Γ-point and greatly improve emitted far-field uniformity. We realize the III-nitride nanowires structures using a top-down fabrication procedure that produces nanowires with smooth, vertical sidewalls. Comparison of room-temperature micro-photoluminescence (µ-PL) measurements between periodic and quasi-aperiodic nanowire arrays reveal resonances in each structure, with the simple periodic structure producing a donut beam in the emitted far-field and the quasi-aperiodic structure producing a uniform Gaussian-like beam. We investigate the input pump power vs. output intensity in both systems and observe the simple periodic array exhibiting a non-linear relationship, indicative of lasing. We believe that the quasi-aperiodic approach studied here provides an alternate and promising strategy for shaping the emission pattern of nanoemitter systems.

Demonstration of an optical phased array using electro-optic polymer phase shifters

Science.gov (United States)

Hirano, Yoshikuni; Motoyama, Yasushi; Tanaka, Katsu; Machida, Kenji; Yamada, Toshiki; Otomo, Akira; Kikuchi, Hiroshi

2018-03-01

We have been investigating an optical phased array (OPA) using electro-optic (EO) polymers in phase shifters to achieve ultrafast optical beam steering. In this paper, we describe the basic structures of the OPA using EO polymer phase shifters and show the beam steering capability of the OPA. The designed OPA has a multimode interference (MMI) beam splitter and 8-channel polymer waveguides with EO polymer phase shifters. We compare 1 × 8 MMI and cascaded 1 × 2 MMI beam splitters numerically and experimentally, and then obtain uniform intensity outputs from the 1 × 8 beam splitter. We fabricate the EO polymer OPA with a 1 × 8 MMI beam splitter to prevent intensity dispersion due to radiation loss in bending waveguides. We also evaluate the optical beam steering capability of the fabricated OPA and found a 2.7° deflection of far-field patterns when applying a voltage difference of 25 V in adjacent phase shifters.

Analysis and Simulation of Multi-target Echo Signals from a Phased Array Radar

OpenAIRE

Jia Zhen; Zhou Rui

2017-01-01

The construction of digital radar simulation systems has been a research hotspot of the radar field. This paper focuses on theoretical analysis and simulation of multi-target echo signals produced in a phased array radar system, and constructs an array antenna element and a signal generation environment. The antenna element is able to simulate planar arrays and optimizes these arrays by adding window functions. And the signal environment can model and simulate radar transmission signals, rada...

Birefringent Microlens Array for Ultra High Resolution HMDs, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will be used to analyze, design, model, and test a birefringent microlens array for use in a new type of...

Robotic inspection of fiber reinforced composites using phased array UT

Science.gov (United States)

Stetson, Jeffrey T.; De Odorico, Walter

2014-02-01

Ultrasound is the current NDE method of choice to inspect large fiber reinforced airframe structures. Over the last 15 years Cartesian based scanning machines using conventional ultrasound techniques have been employed by all airframe OEMs and their top tier suppliers to perform these inspections. Technical advances in both computing power and commercially available, multi-axis robots now facilitate a new generation of scanning machines. These machines use multiple end effector tools taking full advantage of phased array ultrasound technologies yielding substantial improvements in inspection quality and productivity. This paper outlines the general architecture for these new robotic scanning systems as well as details the variety of ultrasonic techniques available for use with them including advances such as wide area phased array scanning and sound field adaptation for non-flat, non-parallel surfaces.

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

Directory of Open Access Journals (Sweden)

Lajla Bruntse Hansen

Full Text Available We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2. Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA and from rabbit serum albumin (RSA were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

Science.gov (United States)

Hansen, Lajla Bruntse; Buus, Soren; Schafer-Nielsen, Claus

2013-01-01

We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2). Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA) as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids) at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA) and from rabbit serum albumin (RSA) were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Analysis and synthesis of (SAR) waveguide phased array antennas

Science.gov (United States)

Visser, H. J.

1994-02-01

This report describes work performed due to ESA contract No. 101 34/93/NL/PB. Started is with a literature study on dual polarized waveguide radiators, resulting in the choice for the open ended square waveguide. After a thorough description of the mode matching infinite waveguide array analysis method - including finiteness effects - that forms the basis for all further described analysis and synthesis methods, the accuracy of the analysis software is validated by comparison with measurements on two realized antennas. These antennas have centered irises in the waveguide apertures and a dielectric wide angle impedance matching sheet in front of the antenna. A synthesis method, using simulated annealing and downhill simplex, is described next and different antenna designs, based on the analysis of a single element in an infinite array environment, are presented. Next, designs of subarrays are presented. Shown is the paramount importance of including the array environment in the design of a subarray. A microstrip patch waveguide exciter and subarray feeding network are discussed and the depth of the waveguide radiator is estimated. Chosen is a rectangular grid array with waveguides of 2.5 cm depth without irises and without dielectric sheet, grouped in linear 8 elements subarrays.

Monolithic Microwave Integrated Circuit (MMIC) Phased Array Demonstrated With ACTS

Science.gov (United States)

1996-01-01

Monolithic Microwave Integrated Circuit (MMIC) arrays developed by the NASA Lewis Research Center and the Air Force Rome Laboratory were demonstrated in aeronautical terminals and in mobile or fixed Earth terminals linked with NASA's Advanced Communications Technology Satellite (ACTS). Four K/Ka-band experimental arrays were demonstrated between May 1994 and May 1995. Each array had GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The 30-GHz transmit array used in uplinks to ACTS was developed by Lewis and Texas Instruments. The three 20-GHz receive arrays used in downlinks from ACTS were developed in cooperation with the Air Force Rome Laboratory, taking advantage of existing Air Force integrated-circuit, active-phased-array development contracts with the Boeing Company and Lockheed Martin Corporation. Four demonstrations, each related to an application of high interest to both commercial and Department of Defense organizations, were conducted. The location, type of link, and the data rate achieved for each of the applications is shown. In one demonstration-- an aeronautical terminal experiment called AERO-X--a duplex voice link between an aeronautical terminal on the Lewis Learjet and ACTS was achieved. Two others demonstrated duplex voice links (and in one case, interactive video links as well) between ACTS and an Army high-mobility, multipurpose wheeled vehicle (HMMWV, or "humvee"). In the fourth demonstration, the array was on a fixed mount and was electronically steered toward ACTS. Lewis served as project manager for all demonstrations and as overall system integrator. Lewis engineers developed the array system including a controller for open-loop tracking of ACTS during flight and HMMWV motion, as well as a laptop data display and recording system used in all demonstrations. The Jet Propulsion Laboratory supported the AERO-X program, providing elements of the ACTS Mobile Terminal. The successful

Phased-array radar design application of radar fundamentals

CERN Document Server

Jeffrey, Thomas

2009-01-01

Phased-Array Radar Design is a text-reference designed for electrical engineering graduate students in colleges and universities as well as for corporate in-house training programs for radar design engineers, especially systems engineers and analysts who would like to gain hands-on, practical knowledge and skills in radar design fundamentals, advanced radar concepts, trade-offs for radar design and radar performance analysis.

Calculation of coupling to slow and fast waves in the LHRF from phased waveguide arrays

International Nuclear Information System (INIS)

Pinsker, R.I.; Duvall, R.E.; Fortgang, C.M.; Colestock, P.L.

1986-04-01

A previously reported algorithm for solving the problem of coupling electromagnetic energy in the LHRF from a phased array of identical rectangular waveguides to a plane-stratified, magnetized cold plasma is numerically implemented. The resulting computer codes are sufficiently general to allow for an arbitrary number of waveguides with finite dimensions in both poloidal and toroidal directions, and are thus capable of computing coupling to both slow and fast waves in the plasma. Some of the details of the implementation and the extension of the algorithm to allow study of the Fourier spectrum of slow and fast waves launched by the array are discussed. Good agreement is found with previously reported, less general work for the slow wave launching case. The effect of phasing multirow arrays in the poloidal direction is studied, and an asymmetry between phasing 'up' and 'down' is found that persists in the case where the plasma adjacent to the array is uniform. A 4 x 3 array designed to launch fast waves of high phase velocity is studied. By using the optimal poloidal phasing, low reflection coefficients (absolute value of R 2 less than or equal to 20%) are found under some not unrealistic edge plasma conditions, but most of the input power is trapped in the outermost layer of the plasma. Implications of our results for fast wave current drive experiments are discussed

GaAs MMIC elements in phased-array antennas

Science.gov (United States)

Leonard, Regis F.

1988-01-01

Over the last six years NASA Lewis Research Center has carried out a program aimed at the development of advanced monolithic microwave integrated circuit technology, principally for use in phased-array antenna applications. Arising out of the Advanced Communications Technology Satellite (ACTS) program, the initial targets of the program were chips which operated at 30 and 20 GHz. Included in this group of activities were monolithic power modules with an output of 2 watts at GHz, variable phase shifters at both 20 and 30 GHz, low noise technology at 30 GHz, and a fully integrated (phase shifter, variable gain amplifier, power amplifier) transmit module at 20 GHz. Subsequent developments are centered on NASA mission requirements, particularly Space Station communications systems and deep space data communications.

Analysis of ultrasonic beam profile due to change of elements' number for phased array transducer (part 2)

International Nuclear Information System (INIS)

Choi, Sang Woo; Lee, Joon Hyun

1998-01-01

The phased array offers many advantages and improvements over conventional single-element transducers such as the straight-beam and angle-beam. The advantages of array sensors for large structures are two folds; firstly, array transducers provide a method of rapid beam steering and sequential addressing of a large area of interest without requiring mechanical or manual scanning which is particularly important in real-time application. Secondly, array transducer provide a method of dynamic focusing, in which the focal length of the ultrasonic beam varies as the pulse propagates through the material. There are some parameters such as number, size, center to center space of elements to design phased array transducer. In previous study. the characteristics of beam steering and dynamic focusing had been simulated for ultrasonic SH-wave with varying the number of phased array transducer's element. In this study, the characteristic of beam steering for phased array transducer has been simulated for ultrasonic SH-wave on the basis of Huygen's principle with varying center to center space of elements. Ultrasonic beam directivity and focusing due to change of time delay of each element were discussed with varying center to center space of elements.

Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy.

Science.gov (United States)

Hynynen, Kullervo; Jones, Ryan M

2016-09-07

Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

Rail flaw sizing using conventional and phased array ultrasonic testing.

Science.gov (United States)

2012-12-01

An approach to detecting and characterizing internal defects in rail through the use of phased array ultrasonic testing has shown the potential to reduce the risk of missed defects and improve transverse defect characterization. : Transportation Tech...

Photonic integration and components development for a Ku-band phased array antenna system

NARCIS (Netherlands)

Marpaung, D.A.I.; Zhuang, L.; Burla, M.; Roeloffzen, C.G.H.; Noharet, Bertrand; Wang, Qin; Beeker, W.P.; Beeker, Willem; Leinse, Arne; Heideman, Rene

2011-01-01

In this paper the development of a phased array antenna system using a photonic beamformer is reported. The paper emphasizes on the photonic integration between two main components of the beamformer, namely the photonic beamformer chip and the electroabsorption modulator array. System level

Distributed 3D Source Localization from 2D DOA Measurements Using Multiple Linear Arrays

Directory of Open Access Journals (Sweden)

Antonio Canclini

2017-01-01

Full Text Available This manuscript addresses the problem of 3D source localization from direction of arrivals (DOAs in wireless acoustic sensor networks. In this context, multiple sensors measure the DOA of the source, and a central node combines the measurements to yield the source location estimate. Traditional approaches require 3D DOA measurements; that is, each sensor estimates the azimuth and elevation of the source by means of a microphone array, typically in a planar or spherical configuration. The proposed methodology aims at reducing the hardware and computational costs by combining measurements related to 2D DOAs estimated from linear arrays arbitrarily displaced in the 3D space. Each sensor measures the DOA in the plane containing the array and the source. Measurements are then translated into an equivalent planar geometry, in which a set of coplanar equivalent arrays observe the source preserving the original DOAs. This formulation is exploited to define a cost function, whose minimization leads to the source location estimation. An extensive simulation campaign validates the proposed approach and compares its accuracy with state-of-the-art methodologies.

One-dimensional phased array with mechanical motion for conformal ultrasound hyperthermia

International Nuclear Information System (INIS)

Ju, Kuen-Cheng; Chen, Yung-Yaw; Lin, Win-Li; Kuo, Te-Son

2003-01-01

This paper investigates the feasibility of conformal heating for external ultrasound hyperthermia by using a phased array transducer with mechanical motion. In this system, a one-dimensional phased array is arranged on a shaft and moves along the shaft, while dynamically focusing on the planning target volume (PTV) with numerous focal spots. To prevent overheating in the intervening tissue between the skin and the PTV, the shaft and the phased array are rotated together to enlarge the acoustical window. With the purpose of conformal heating, the power deposition of the PTV is constructed by combinations of the focal spots and an iterative gradient descent method is then used to determine an optimal set of power weightings for the focal spots. Different tumour shapes are evaluated and the simulation results demonstrate that the volume percentage of the PTV with temperatures higher than 43 deg. C is over 95%. The overheating volume outside the PTV is less than 25% of the PTV. This method provides good conformal heating for external ultrasound hyperthermia. The concept of combining electrical focusing and mechanical motion has the advantages of both enlarging the acoustic window and providing dynamic focusing ability, which is essential for successful conformal heating

Dynamic Phases in Driven Vortex Lattices in Superconductors with Periodic Pinning Arrays.

Science.gov (United States)

Reichhardt, C.; Olson, C. J.; Nori, F.

1997-03-01

In an extensive series of simulations of driven vortices interacting with periodic pinning arrays, an extremely rich variety of novel plastic flow phases, very distinct from those observed in random arrays, are found as a function of applied driving force. We show that signatures of the transitions between these different dynamical phases appear as pronounced jumps and dips in the I-V curves, coinciding with marked changes in the microscopic structure and flow behavior of the vortex lattice. When the number of vortices is greater than the number of pinning sites, we observe up to six distinct dynamical phases, including a pinned phase, a flow of interstitial vortices between pinned vortices, a disordered flow, a 1D flow along the pinning rows, and a homogeneous flow. By varying a wide range of microscopic pinning parameters, including pinning strength, size, density, and degree of ordering, as well as varying temperature and commensurability, we obtain a series of dynamic phase diagrams. nori>A short video will also be presented to highlight these different dynamic phases.

ELECTROMAGNETIC SCATTERING AND ANTENNA TECHNOLOGY (EMSAT) Task Order 0003: Design of a Circularly Polarized, 20 60 GHZ Active Phased Array for Wide Angle Scanning

Science.gov (United States)

2017-08-08

previously published linear -to-circular polarizers. This is because the first sheet has a low inductance in the -direction, which acts as a wire-grid...GHZ Active Phased Array for Wide Angle Scanning Carl R. Pfeiffer Defense Engineering Corporation Boris Tomasic Multispectral Sensing and...GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62204F/61102F 6. AUTHOR(S) Carl R. Pfeiffer (Defense Engineering Corporation) Boris Tomasic (AFRL

Three-dimensional mid-air acoustic manipulation by ultrasonic phased arrays.

Science.gov (United States)

Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun

2014-01-01

The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method.

Phase diagram of a QED-cavity array coupled via a N-type level scheme

Energy Technology Data Exchange (ETDEWEB)

Jin, Jiasen; Rossini, Davide [CNR, NEST, Scuola Normale Superiore and Istituto di Nanoscienze, Pisa (Italy); Fazio, Rosario [CNR, NEST, Scuola Normale Superiore and Istituto di Nanoscienze, Pisa (Italy); National University of Singapore, Center for Quantum Technologies, Singapore (Singapore)

2015-01-01

We study the zero-temperature phase diagram of a one-dimensional array of QED cavities where, besides the single-photon hopping, an additional coupling between neighboring cavities is mediated by an N-type four-level system. By varying the relative strength of the various couplings, the array is shown to exhibit a variety of quantum phases including a polaritonic Mott insulator, a density-wave and a superfluid phase. Our results have been obtained by means of numerical density-matrix renormalization group calculations. The phase diagram was obtained by analyzing the energy gaps for the polaritons, as well as through a study of two-point correlation functions. (orig.)

Evidence of performance for phased array/ALOK-inspection technique

International Nuclear Information System (INIS)

Bohn, H.; Kroening, M.; Rathgeb, W.; Gebhardt, W.; Kappes, W.; Barbian, O.A.

1986-01-01

Phased-array probes combined with the ALOK method give an US test system which results in major improvements of automated ultrasonic testing of pressure vessels. The authors discuss the improvements in test execution, defect detection and interpretation by means of tandem defects and defect detection in fault displays. (DG) [de

Parallel-fed planar dipole antenna arrays for low-observable platforms

CERN Document Server

Singh, Hema; Jha, Rakesh Mohan

2016-01-01

This book focuses on determination of scattering of parallel-fed planar dipole arrays in terms of reflection and transmission coefficients at different levels of the array system. In aerospace vehicles, the phased arrays are often in planar configuration. The radar cross section (RCS) of the vehicle is mainly due to its structure and the antennas mounted over it. There can be situation when the signatures due to antennas dominate over the structural RCS of the platform. This necessitates the study towards the reduction and control of antenna/ array RCS. The planar dipole array is considered as a stacked linear dipole array. A systematic, step-by-step approach is used to determine the RCS pattern including the finite dimensions of dipole antenna elements. The mutual impedance between the dipole elements for planar configuration is determined. The scattering till second-level of couplers in parallel feed network is taken into account. The phase shifters are modelled as delay line. All the couplers in the feed n...

Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

Science.gov (United States)

Zhou, Guoquan

2011-11-21

A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail. © 2011 Optical Society of America

Supersymmetric phase transition in Josephson-tunnel-junction arrays

Energy Technology Data Exchange (ETDEWEB)

Foda, O.

1988-08-31

The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T/sub I/less than or equal toT/sub V/, then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T/sub I/=T/sub V/. Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory.

Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

Science.gov (United States)

Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

1986-01-01

A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

3D Analytical Calculation of Forces between Linear Halbach-Type Permanent Magnet Arrays

OpenAIRE

Allag , Hicham; Yonnet , Jean-Paul; Latreche , Mohamed E. H.

2009-01-01

International audience; Usely, in analytical calculation of magnetic and mechanical quantities of Halbach systems, the authors use the Fourier series approximation because the exact calculations are more difficult. In this work the interaction forces between linear Halbach arrays are analytically calculated thanks to our recent development 3D exact calculation of forces between two cuboïdal magnets with parallel and perpendicular magnetization. We essentially describe the way to separately ca...

Ultrasonic testing with the phased array method at the pipe connection inner edges in pipings

International Nuclear Information System (INIS)

Brekow, G.; Wuestenberg, H.; Hesselmann, H.; Rathgeb, W.

1991-01-01

Ultrasonic testing with the phased array method at the pipe connection inner edges in pipings. The pipe connection inner corner tests in feedwater lines to the main coolant pipe were carried out by Preussen-Elektra in cooperation with Siemens KWU and the BAM with the ultrasonic phased array method. The testing plan was developed by means of a computed model. For a trial of the testing plan, numerous ultrasonic measurements with the phased array method were carried out using a pipe test piece with TH-type inner edges, which was a 1:1 model of the reactor component to be tested. The data measured at several test notches in the pipe connection inner edge area covered by a plating of 6 mm were analyzed. (orig./MM) [de

Gravitational waves from a supercooled electroweak phase transition and their detection with pulsar timing arrays

Energy Technology Data Exchange (ETDEWEB)

Kobakhidze, Archil; Lagger, Cyril; Manning, Adrian [University of Sydney, ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, Sydney, NSW (Australia); Yue, Jason [National Taiwan Normal University, Department of Physics, Taipei (China)

2017-08-15

We investigate the properties of a stochastic gravitational wave background produced by a first-order electroweak phase transition in the regime of extreme supercooling. We study a scenario whereby the percolation temperature that signifies the completion of the transition, T{sub p}, is as low as a few MeV (nucleosynthesis temperature), while most of the true vacuum bubbles are formed much earlier at the nucleation temperature, T{sub n} ∝ 50 GeV. This implies that the gravitational wave spectrum is mainly produced by the collisions of large bubbles and characterised by a large amplitude and a peak frequency as low as f ∝ 10{sup -9}-10{sup -7} Hz. We show that such a scenario can occur in (but not limited to) a model based on a non-linear realisation of the electroweak gauge group, so that the Higgs vacuum configuration is altered by a cubic coupling. In order to carefully quantify the evolution of the phase transition of this model over such a wide temperature range we go beyond the usual fast transition approximation, taking into account the expansion of the Universe as well as the behaviour of the nucleation probability at low temperatures. Our computation shows that there exists a range of parameters for which the gravitational wave spectrum lies at the edge between the exclusion limits of current pulsar timing array experiments and the detection band of the future Square Kilometre Array observatory. (orig.)

Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

Energy Technology Data Exchange (ETDEWEB)

Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

2010-12-15

Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

Innovative phased array ultrasonic inspection solution for large rotor shafts

Energy Technology Data Exchange (ETDEWEB)

Maes, G.; Devos, D.; Tremblay, P., E-mail: gmaes@zetec.com [Zetec, Ville de Quebec, Quebec (Canada)

2016-05-15

The increasing needs of energy production led to new rotor shaft designs with larger dimensions. A new generation of nuclear power plants is already being deployed worldwide with such heavy components. Their implementation requires new inspection tools in order to guarantee the public safety and to ensure the quality of these critical parts. Due to the long sound path, conventional ultrasonic (UT) techniques cannot provide adequate detectability of the reference reflectors required by the existing codes. Also, some standards require multiple angle beams to be applied in addition to the straight beam inspection, and this leads to long inspection times. This paper will address the implementation and validation of phased array (PA) UT techniques, using a semi-flexible 2D array probe, for the inspection of large mono-block rotor shaft forgings. It will show how the beam focusing and steering capabilities of phased array UT probes can be used to overcome the issues occurring with conventional UT probes. Results of acoustic beam simulation, as well as detectability measurements and data acquisitions on representative test specimens will be presented and compared with conventional UT performance. Various aspects of the hardware and software specification will be addressed, as well as the potential reduction of the total inspection time. (author)

Development of ultrasonic inspection equipment using phased array method

International Nuclear Information System (INIS)

Kikuchi, Osamu; Yamatoya, Naofumi; Umino, Tomohiro; Baba, Atsushi

2008-01-01

This study presents new phased array UT equipments, one is developed as portable type for field inspection and the other is developed for 2D-matrix array (3D Focus-UT). The pulser of square burst wave was adopted for these new equipments to enhance flaw echo amplitude. At over 3 cycles of square burst cycle, the authors confirmed over 10 dB enhancement of bottom echo amplitude. Moreover, a new flaw imaging method using S-SAFT was also adopted for equipments to improve SN ratio and flaw echo resolution in inspection image. The authors verified effects of S-SAFT using side drilled hole specimen, about 2 times of improvement of SN ratio and flaw echo resolution. (author)

Simultaneous Transmit and Receive Performance of an 8-channel Digital Phased Array

Science.gov (United States)

2017-01-16

hardware. An 8-channel ALSTAR array prototype was constructed and demonstrated to achieve 125.5 dB effective isotropic isolation between broadside...transmit and receive beams over a 100 MHz instantaneous band centered at 2.45 GHz. I. INTRODUCTION A phased array capable of Simultaneous Transmit and...Receive (STAR) could provide significant benefits for many applications including communications, radar, spectral sens- ing, and multifunctional systems

Looking Below the Surface with Ultrasonic Phased Array

International Nuclear Information System (INIS)

Cinson, Anthony D.; Crawford, Susan L.

2010-01-01

This article is a brief tutorial on the benefits of volumetric ultrasonic phased array line scanning. The article describes the need, the approach, and the methods/practices used to analyze the data for flaw detection and characterization in the nuclear power plant component arena. If you are inspecting the integrity of nuclear power plant components during a scheduled outage, time is likely against you. Time is a luxury that most inspectors do not possess in their daily jobs. They are required to quickly and efficiently perform nondestructive testing (NDT) on various components within the nuclear power plant facility. In addition to the obvious financial impacts ($1M+ per day) of prolonging planned outages, time constraints also are put in place for the safety and health of the inspectors. For instance, while working in highly radioactive or contaminated environments of the plant, inspectors have a limited window of time to volumetrically inspect components for flaws, such as cracks, defects or other anomalies that might lead to leakage or failure during operation. In the interest of simplicity, flaws are limited to cracks for our purposes. Ultrasonic phased array volumetric line scanning is emerging as a powerful tool that allows for quick inspections of components that had been very time-consuming using earlier technologies.

Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

Science.gov (United States)

Song, Sung-Jin; Kim, Chang-Hwan

2002-05-01

Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

Wireless Power Transfer to a Microaerial Vehicle with a Microwave Active Phased Array

Directory of Open Access Journals (Sweden)

Shotaro Nako

2014-01-01

Full Text Available A wireless power transfer system using a microwave active phased array was developed. In the system, power is transferred to a circling microaerial vehicle (MAV by a microwave beam of 5.8 GHz, which is formed and directed to the MAV using an active phased array antenna. The MAV is expected to support observation of areas that humans cannot reach. The power beam is formed by the phased array with eight antenna elements. Input power is about 5.6 W. The peak power density at 1,500 mm altitude was 2.63 mW/cm2. The power is sent to a circling MAV. Therefore, the transfer beam should be polarized circularly to achieve a constant power supply independent of its yaw angle. To minimize the polarization loss, a sequentially routed antenna (SRA was applied to the transmitter antenna. Results show that the axial ratio of 0.440 dB was accomplished and that power fluctuation was kept below 1%.

Three-dimensional mid-air acoustic manipulation by ultrasonic phased arrays.

Directory of Open Access Journals (Sweden)

Yoichi Ochiai

Full Text Available The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method.

Structural-electrical coupling optimisation for radiating and scattering performances of active phased array antenna

Science.gov (United States)

Wang, Congsi; Wang, Yan; Wang, Zhihai; Wang, Meng; Yuan, Shuai; Wang, Weifeng

2018-04-01

It is well known that calculating and reducing of radar cross section (RCS) of the active phased array antenna (APAA) are both difficult and complicated. It remains unresolved to balance the performance of the radiating and scattering when the RCS is reduced. Therefore, this paper develops a structure and scattering array factor coupling model of APAA based on the phase errors of radiated elements generated by structural distortion and installation error of the array. To obtain the optimal radiating and scattering performance, an integrated optimisation model is built to optimise the installation height of all the radiated elements in normal direction of the array, in which the particle swarm optimisation method is adopted and the gain loss and scattering array factor are selected as the fitness function. The simulation indicates that the proposed coupling model and integrated optimisation method can effectively decrease the RCS and that the necessary radiating performance can be simultaneously guaranteed, which demonstrate an important application value in engineering design and structural evaluation of APAA.

A K/Ka band radiating element for Tx/Rx phased array

KAUST Repository

Sandhu, Ali Imran; Arnieri, E.; Amendola, G.; Boccia, L.; Meniconi, E.; Ziegler, V.

2017-01-01

The paper presents a K/Ka band radiating element for TX/RX phased arrays. Dual band operations is obtained using a single radiating surface: a novel radiator is adopted and placed in a configuration in which dual band and single band elements are interleaved. The array elements are optimized to scan the beam in excess of 50° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

A K/Ka band radiating element for Tx/Rx phased array

KAUST Repository

Sandhu, Ali Imran

2017-01-20

The paper presents a K/Ka band radiating element for TX/RX phased arrays. Dual band operations is obtained using a single radiating surface: a novel radiator is adopted and placed in a configuration in which dual band and single band elements are interleaved. The array elements are optimized to scan the beam in excess of 50° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

Plasma resistance behavior during the linear decay phase of RFPs in ETA BETA II

International Nuclear Information System (INIS)

Nalesso, G.F.

1982-01-01

In the aided-reversal mode RFP discharges produced in ETA BETA II, the plasma current is characterized by a linear decay phase, which follows an approximately exponential phase. During the same period the measured toroidal voltage is negative and initially increasing in absolute value (exponential phase) and then decreasing to almost zero during the linear phase before the current termination. The same behavior of the current has been observed in the quiescent phase in Zeta where a negative toroidal electric field was also observed. In this note we present a model that can explain the linear decay phase and fits with the experimental parameters and allows us to estimate the plasma resistance behavior during the linear phase of slow reversed field pinch discharges

Experimental study of the retention properties of a cyclo olefin polymer pillar array column in reversed-phase mode.

Science.gov (United States)

Illa, Xavi; De Malsche, Wim; Gardeniers, Han; Desmet, Gert; Romano-Rodríguez, Albert

2010-11-01

Experimental measurements to study the retention capacity and band broadening under retentive conditions using micromachined non-porous pillar array columns fabricated in cyclo olefin polymer are presented. In particular, three columns with different depths but with the same pillar structure have been fabricated via hot embossing and pressure-assisted thermal bonding. Separations of a mixture of four coumarins using varying mobile phase compositions have been monitored to study the relation between the retention factor and the ratio of organic solvent in the aqueous mobile phase. Moreover, the linear relation between the retention and the surface/volume ratio predicted in theory has been observed, achieving retention factors up to k=2.5. Under the same retentive conditions, minimal reduced plate height values of h(min)=0.4 have been obtained at retention factors of k=1.2. These experimental results are compared with the case of non-porous and porous silicon pillars. Similar results for the plate heights are achieved while retention factors are higher than the non-porous silicon column and considerably smaller than the porous pillar column, given the non-porous nature of the used cyclo olefin polymer. The feasibility of using this polymer column as an alternative to the pillar array silicon columns is corroborated.

Design of a linear detector array unit for high energy x-ray helical computed tomography and linear scanner

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeong Tae; Park, Jong Hwan; Kim, Gi Yoon [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of); Kim, Dong Geun [Medical Imaging Department, ASTEL Inc., Seongnam (Korea, Republic of); Park, Shin Woong; Yi, Yun [Dept. of Electronics and Information Eng, Korea University, Seoul (Korea, Republic of); Kim, Hyun Duk [Research Center, Luvantix ADM Co., Ltd., Daejeon (Korea, Republic of)

2016-11-15

A linear detector array unit (LdAu) was proposed and designed for the high energy X-ray 2-d and 3-d imaging systems for industrial non-destructive test. Specially for 3-d imaging, a helical CT with a 15 MeV linear accelerator and a curved detector is proposed. the arc-shape detector can be formed by many LdAus all of which are arranged to face the focal spot when the source-to-detector distance is fixed depending on the application. An LdAu is composed of 10 modules and each module has 48 channels of CdWO{sub 4} (CWO) blocks and Si PIn photodiodes with 0.4 mm pitch. this modular design was made for easy manufacturing and maintenance. through the Monte carlo simulation, the CWO detector thickness of 17 mm was optimally determined. the silicon PIn photodiodes were designed as 48 channel arrays and fabricated with NTD (neutron transmutation doping) wafers of high resistivity and showed excellent leakage current properties below 1 nA at 10 V reverse bias. to minimize the low-voltage breakdown, the edges of the active layer and the guard ring were designed as a curved shape. the data acquisition system was also designed and fabricated as three independent functional boards; a sensor board, a capture board and a communication board to a Pc. this paper describes the design of the detectors (CWO blocks and Si PIn photodiodes) and the 3-board data acquisition system with their simulation results.

Phase unwrapping algorithm using polynomial phase approximation and linear Kalman filter.

Science.gov (United States)

Kulkarni, Rishikesh; Rastogi, Pramod

2018-02-01

A noise-robust phase unwrapping algorithm is proposed based on state space analysis and polynomial phase approximation using wrapped phase measurement. The true phase is approximated as a two-dimensional first order polynomial function within a small sized window around each pixel. The estimates of polynomial coefficients provide the measurement of phase and local fringe frequencies. A state space representation of spatial phase evolution and the wrapped phase measurement is considered with the state vector consisting of polynomial coefficients as its elements. Instead of using the traditional nonlinear Kalman filter for the purpose of state estimation, we propose to use the linear Kalman filter operating directly with the wrapped phase measurement. The adaptive window width is selected at each pixel based on the local fringe density to strike a balance between the computation time and the noise robustness. In order to retrieve the unwrapped phase, either a line-scanning approach or a quality guided strategy of pixel selection is used depending on the underlying continuous or discontinuous phase distribution, respectively. Simulation and experimental results are provided to demonstrate the applicability of the proposed method.

Standard guide for evaluating performance characteristics of phased-Array ultrasonic testing instruments and systems

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 This guide describes procedures for evaluating some performance characteristics of phased-array ultrasonic examination instruments and systems. 1.2 Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this guide are expressed in terms that relate to their potential usefulness for ultrasonic examinations. Other electronic instrument characteristics in phased-array units are similar to non-phased-array units and may be measured as described in E 1065 or E 1324. 1.3 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated. 1.4 This guide establishes no performance limits for examination systems; if such acceptance criteria ar...

Efficient coherent beam combination of two-dimensional phase-locked laser arrays

International Nuclear Information System (INIS)

Li, Bing; Yan, Aimin; Liu, Liren; Dai, Enwen; Sun, Jianfeng; Shen, Baoliang; Lv, Xiaoyu; Wu, Yapeng

2011-01-01

An efficient technique in which a two-dimensional (2D) phase-locked laser array can be coherently combined into a high power and high quality beam by using a conjugate Dammann grating (CDG) is presented. A theoretical model is established to provide a physical interpretation of the proposed scheme. Using this technique, we investigate analytically and numerically the coherent combination of 2D laser arrays such as 5 × 5 and 32 × 32 arrangements. Far-field distributions and the near-field pattern of the combined beam are calculated and compared with experimental results. A verification experiment with a simulated 5 × 5 2D laser array using an aperture mask has been performed. Calculations and experimental results show that the proposed technique in this paper is an efficient coherent beam combination method to obtain a high power and high quality beam from laser arrays

Evaluation of Methods for In-Situ Calibration of Field-Deployable Microphone Phased Arrays

Science.gov (United States)

Humphreys, William M.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.

2017-01-01

Current field-deployable microphone phased arrays for aeroacoustic flight testing require the placement of hundreds of individual sensors over a large area. Depending on the duration of the test campaign, the microphones may be required to stay deployed at the testing site for weeks or even months. This presents a challenge in regards to tracking the response (i.e., sensitivity) of the individual sensors as a function of time in order to evaluate the health of the array. To address this challenge, two different methods for in-situ tracking of microphone responses are described. The first relies on the use of an aerial sound source attached as a payload on a hovering small Unmanned Aerial System (sUAS) vehicle. The second relies on the use of individually excited ground-based sound sources strategically placed throughout the array pattern. Testing of the two methods was performed in microphone array deployments conducted at Fort A.P. Hill in 2015 and at Edwards Air Force Base in 2016. The results indicate that the drift in individual sensor responses can be tracked reasonably well using both methods. Thus, in-situ response tracking methods are useful as a diagnostic tool for monitoring the health of a phased array during long duration deployments.

Phase Locking and Chaos in a Josephson Junction Array Shunted by a Common Resistance

International Nuclear Information System (INIS)

Tie-Ge, Zhou; Jing, Mao; Ting-Shu, Liu; Yue, Lai; Shao-Lin, Yan

2009-01-01

The dynamics of a Josephson junction array shunted by a common resistance are investigated by using numerical methods. Coexistence of phase locking and chaos is observed in the system when the resistively and capacitively shunted junction model is adopted. The corresponding parameter ranges for phase locking and chaos are presented. When there are three resistively shunted junctions in the array, chaos is found for the first time and the parameter range for chaos is also presented. According to the theory of Chernikov and Schmidt, when there are four or more junctions in the array, the system exhibits chaotic behavior. Our results indicate that the theory of Chernikov and Schmidt is not exactly appropriate. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

P-S & S-P Elastic Wave Conversions from Linear Arrays of Oriented Microcracks

Science.gov (United States)

Jiang, L.; Modiriasari, A.; Bobet, A.; Pyrak-Nolte, L. J.

2017-12-01

Natural and induced processes can produce oriented mechanical discontinuities such as en echelon cracks, fractures and faults. Previous research has shown that compressional to shear (P-S) wave conversions occur at normal incidence to a fracture because of cross-coupling fracture compliances (Nakagawa et al., 2000). Here, experiments and computer simulation are presented to demonstrate the link among cross-coupling stiffness, microcrack orientation and energy partitioning among P, S, and P-S/S-P waves. A FormLabs 2 3D printer was used to fabricate 7 samples (50 mm x 50 mm x 100 mm) with linear arrays of microcracks oriented at 0, 15, 30, 45, 60, 75, and 900 with a print resolution of 0.025 mm. The microcracks were elliptical in cross-sections (2 mm long by 1 mm wide), through the 50 mm thickness of sample, and spaced 3 mm (center-to-center for adjacent cracks). A 25 mm length of each sample contained no microcracks to act as a reference material. Broadband transducers (0.2-1.5 MHz) were used to transmit and receive P and polarized S wave signals that were propagated at normal incidence to the linear array of microcracks. P-wave amplitude increased, while S-wave amplitude remained relatively constant, as the microcrack orientation increased from 0o to 90o. At normal incidence, P-S and S-P wave conversions emerged and increased in amplitude as the crack inclination increased from 00 to 450. From 450 to 900, the amplitude of these converted modes decreased. Between negative and positive crack angles, the P-to-S and S-to-P waves were 1800 phase reversed. The observed energy partitioning matched the computed compliances obtained from numerical simulations with ABAQUS. The cross-coupling compliance for cracks inclined at 450 was found to be the smallest magnitude. 3D printing enabled the study of microstructural effects on macro-scale wave measurements. Information on the orientation of microcracks or even en echelon fractures and faults is contained in P-S conversions

A supersymmetric phase transition in Josephson-tunnel-junction arrays

International Nuclear Information System (INIS)

Foda, O.

1988-01-01

The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T I ≤T V , then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T I =T V . Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory. (orig.)

Experimental demonstration of conformal phased array antenna via transformation optics.

Science.gov (United States)

Lei, Juan; Yang, Juxing; Chen, Xi; Zhang, Zhiya; Fu, Guang; Hao, Yang

2018-02-28

Transformation Optics has been proven a versatile technique for designing novel electromagnetic devices and it has much wider applicability in many subject areas related to general wave equations. Among them, quasi-conformal transformation optics (QCTO) can be applied to minimize anisotropy of transformed media and has opened up the possibility to the design of broadband antennas with arbitrary geometries. In this work, a wide-angle scanning conformal phased array based on all-dielectric QCTO lens is designed and experimentally demonstrated. Excited by the same current distribution as such in a conventional planar array, the conformal system in presence of QCTO lens can preserve the same radiation characteristics of a planar array with wide-angle beam-scanning and low side lobe level (SLL). Laplace's equation subject to Dirichlet-Neumann boundary conditions is adopted to construct the mapping between the virtual and physical spaces. The isotropic lens with graded refractive index is realized by all-dielectric holey structure after an effective parameter approximation. The measurements of the fabricated system agree well with the simulated results, which demonstrate its excellent wide-angle beam scanning performance. Such demonstration paves the way to a robust but efficient array synthesis, as well as multi-beam and beam forming realization of conformal arrays via transformation optics.

Characteristic Assessments of the Phased Array UT System Developed by KHNP

Energy Technology Data Exchange (ETDEWEB)

Cho, Chan-Hee; Jee, Dong-Hyun; Lee, Tae-Hun; Yoo, Hyun-Ju [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

The ultrasonic testing (UT) is an important one of the nondestructive examination methods which are used for the in-service inspection in the nuclear power plant. It is mainly used for the inspection of welds in piping and nozzle for many components. Technologies for the ultrasonic testing have been advanced for the reduction of inspection time and the increase of inspection reliability. In the manual ultrasonic testing system, it is not easy to compare the variation of inspection signals over time, because the data cannot be stored during the inspection. For the purpose of inspecting nuclear power components, the KHNP developed a phased array UT system including pulser-receiver, AD converter, beam-former, phased array probe, and scanner with 3-directional degree of freedom. Characteristics of the KHNP PA system and the results of acquired signals are described in detail in this paper.

Characteristic Assessments of the Phased Array UT System Developed by KHNP

International Nuclear Information System (INIS)

Cho, Chan-Hee; Jee, Dong-Hyun; Lee, Tae-Hun; Yoo, Hyun-Ju

2016-01-01

The ultrasonic testing (UT) is an important one of the nondestructive examination methods which are used for the in-service inspection in the nuclear power plant. It is mainly used for the inspection of welds in piping and nozzle for many components. Technologies for the ultrasonic testing have been advanced for the reduction of inspection time and the increase of inspection reliability. In the manual ultrasonic testing system, it is not easy to compare the variation of inspection signals over time, because the data cannot be stored during the inspection. For the purpose of inspecting nuclear power components, the KHNP developed a phased array UT system including pulser-receiver, AD converter, beam-former, phased array probe, and scanner with 3-directional degree of freedom. Characteristics of the KHNP PA system and the results of acquired signals are described in detail in this paper

Comparison of pelvic phased-array versus endorectal coil magnetic resonance imaging at 3 Tesla for local staging of prostate cancer.

Science.gov (United States)

Kim, Bum Soo; Kim, Tae-Hwan; Kwon, Tae Gyun; Yoo, Eun Sang

2012-05-01

Several studies have demonstrated the superiority of endorectal coil magnetic resonance imaging (MRI) over pelvic phased-array coil MRI at 1.5 Tesla for local staging of prostate cancer. However, few have studied which evaluation is more accurate at 3 Tesla MRI. In this study, we compared the accuracy of local staging of prostate cancer using pelvic phased-array coil or endorectal coil MRI at 3 Tesla. Between January 2005 and May 2010, 151 patients underwent radical prostatectomy. All patients were evaluated with either pelvic phased-array coil or endorectal coil prostate MRI prior to surgery (63 endorectal coils and 88 pelvic phased-array coils). Tumor stage based on MRI was compared with pathologic stage. We calculated the specificity, sensitivity and accuracy of each group in the evaluation of extracapsular extension and seminal vesicle invasion. Both endorectal coil and pelvic phased-array coil MRI achieved high specificity, low sensitivity and moderate accuracy for the detection of extracapsular extension and seminal vesicle invasion. There were statistically no differences in specificity, sensitivity and accuracy between the two groups. Overall staging accuracy, sensitivity and specificity were not significantly different between endorectal coil and pelvic phased-array coil MRI.

Radar cross section of dipole phased arrays with parallel feed network

CERN Document Server

Singh, Hema; Jha, Rakesh Mohan

2016-01-01

This book presents the detailed analytical formulation for the RCS of parallel-fed linear dipole array in the presence of mutual coupling. The radar cross section (RCS) of an object represents its electromagnetic (EM) scattering properties for a given incident wave. The analysis of scattered field is critical in military and defence arenas, especially while designing low-observable platforms. It is well-known that the presence of an antenna/array on the target influences its echo area significantly. The primary cause for such scattering of the incident signals is reflection that occurs within the antenna aperture and its feed network. In this book, the RCS estimation is done based on the signal path within the antenna system. The scattered field is expressed in terms of array design parameters including the reflection and transmission coefficients. The computed results show the variation in the RCS pattern with and without mutual coupling. The effect of finite dipole-length, inter-element spacing, scan angle,...

Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

Energy Technology Data Exchange (ETDEWEB)

Le Bourdais, F.; Le Polles, T. [Non Destructive Testing Department at the French Atomic Energy Commission (CEA), Saclay, 91191 Gif sur Yvette CEDEX, (France); Baque, F. [Department of Sodium Technology at the French Atomic Energy Commission (CEA), Cadarache, 13108 St Paul lez Durance CEDEX, (France)

2015-07-01

This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

International Nuclear Information System (INIS)

Le Bourdais, F.; Le Polles, T.; Baque, F.

2015-01-01

This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

Development of high-performance phased-array UT system 'DYNARAY' and its application examples

International Nuclear Information System (INIS)

Ehara, Eiji

2011-01-01

This article outlined the history leading to develop high-performance phased-array (PA) UT system called DYNARAY, with up to 256 phased-array active channels and maximum 4096 focal laws, lowering the inspection time. As examples it was applied to in-service inspection of reactor pressure vessel welded joints using module of PA-UT probe or eddy-current probe, inspection of seal welds of dry storage containers using scanner of PA-UT, crack detection of end ring of generators using PA-UT probe and UT inspection of cast austenitic stainless steel using 500 kHz probe. Advanced data acquisition and analysis functions for PA-UT system had been developed. (T. Tanaka)

Frequency-domain imaging algorithm for ultrasonic testing by application of matrix phased arrays

Directory of Open Access Journals (Sweden)

Dolmatov Dmitry

2017-01-01

Full Text Available Constantly increasing demand for high-performance materials and systems in aerospace industry requires advanced methods of nondestructive testing. One of the most promising methods is ultrasonic imaging by using matrix phased arrays. This technique allows to create three-dimensional ultrasonic imaging with high lateral resolution. Further progress in matrix phased array ultrasonic testing is determined by the development of fast imaging algorithms. In this article imaging algorithm based on frequency domain calculations is proposed. This approach is computationally efficient in comparison with time domain algorithms. Performance of the proposed algorithm was tested via computer simulations for planar specimen with flat bottom holes.

Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

Science.gov (United States)

Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

2015-11-20

In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

Examination of measurement and its method of compensation of the sensitivity distribution using phased array coil for body scan

CERN Document Server

Kimura, T; Iizuka, A; Taniguchi, Y; Ishikuro, A; Hongo, T; Inoue, H; Ogura, A

2003-01-01

The influence on the quality of images by measurement of a sensitivity distribution and the use of a sensitivity compensation filter was considered using an opposite-type phased array coil and volume-type phased array coil. With the opposite-type phased array coil, the relation between coil interval and filter was investigated for the image intensity correction (IIC) filter, surface coil intensity correction (SCIC) filter (GE), and the Normalize filter (SIEMENS). The SCIC filter and Normalize filter showed distance dependability over the coil interval of signal-to-noise ratio (SNR) and uniformity was observed, and the existence of an optimal coil interval was suggested. Moreover, with the IIC filter, distance dependability over a coil interval was small, and the decrease in contrast with use was remarkable. On the other hand, with the volume-type phased array coil, the overlap of an array element was investigated to determine the influence it had on sensitivity distribution. Although the value stabilized in t...

An Extended Two-Phase Method for Accessing Sections of Out-of-Core Arrays

Directory of Open Access Journals (Sweden)

Rajeev Thakur

1996-01-01

Full Text Available A number of applications on parallel computers deal with very large data sets that cannot fit in main memory. In such applications, data must be stored in files on disks and fetched into memory during program execution. Parallel programs with large out-of-core arrays stored in files must read/write smaller sections of the arrays from/to files. In this article, we describe a method for accessing sections of out-of-core arrays efficiently. Our method, the extended two-phase method, uses collective l/O: Processors cooperate to combine several l/O requests into fewer larger granularity requests, to reorder requests so that the file is accessed in proper sequence, and to eliminate simultaneous l/O requests for the same data. In addition, the l/O workload is divided among processors dynamically, depending on the access requests. We present performance results obtained from two real out-of-core parallel applications – matrix multiplication and a Laplace's equation solver – and several synthetic access patterns, all on the Intel Touchstone Delta. These results indicate that the extended two-phase method significantly outperformed a direct (noncollective method for accessing out-of-core array sections.

Phase transition in nonuniform Josephson arrays: Monte Carlo simulations

Science.gov (United States)

Lozovik, Yu. E.; Pomirchy, L. M.

1994-01-01

Disordered 2D system with Josephson interactions is considered. Disordered XY-model describes the granular films, Josephson arrays etc. Two types of disorder are analyzed: (1) randomly diluted system: Josephson coupling constants J ij are equal to J with probability p or zero (bond percolation problem); (2) coupling constants J ij are positive and distributed randomly and uniformly in some interval either including the vicinity of zero or apart from it. These systems are simulated by Monte Carlo method. Behaviour of potential energy, specific heat, phase correlation function and helicity modulus are analyzed. The phase diagram of the diluted system in T c-p plane is obtained.

Evidence of hexatic phase formation in two-dimensional Lennard-Jones binary arrays

International Nuclear Information System (INIS)

Li, M.; Johnson, W.L.; Goddard, W.A. III

1996-01-01

We report evidence of the hexatic phase formation in Lennard-Jones binary substitutional random arrays from isothermal-isobaric molecular-dynamics simulations. The hexatic phase is analogous to those predicted in Kosterlitz-Thouless theory of melting that is characterized by short-range translational order and quasi-long-range orientational order. At the crystal to hexatic phase transition, dislocation pairs are observed to unbind into isolated dislocations. Further disordering of the hexatic phase, however, does not lead to dissociation of dislocations into disclinations. Instead, the dislocations become clustered and form dislocation networks which results in formation of amorphous phases. copyright 1996 The American Physical Society

ZnO nanorod array solid phase micro-extraction fiber coating: fabrication and extraction capability

International Nuclear Information System (INIS)

Wang Dan; Zhang Zhuomin; Li Tiemei; Zhang Lan; Chen Guonan; Luo Lin

2009-01-01

In this paper, a ZnO nanorod array has been introduced as a coating to the headspace solid phase micro-extraction (HSSPME) field. The coating shows good extraction capability for volatile organic compounds (VOCs) by use of BTEX as a standard and can be considered suitable for sampling trace and small molecular VOC targets. In comparison with the randomly oriented ZnO nanorod HSSPME coating, ZnO nanorod array HSSPME fiber coating shows better extraction capability, which is attributed to the nanorod array structure of the coating. Also, this novel nanorod array coating shows good extraction selectivity to 1-propanethiol.

Compressive Sensing for Millimeter Wave Antenna Array Diagnosis

KAUST Repository

Eltayeb, Mohammed E.

2018-01-08

The radiation pattern of an antenna array depends on the excitation weights and the geometry of the array. Due to wind and atmospheric conditions, outdoor millimeter wave antenna elements are subject to full or partial blockages from a plethora of particles like dirt, salt, ice, and water droplets. Handheld devices are also subject to blockages from random finger placement and/or finger prints. These blockages cause absorption and scattering to the signal incident on the array, modify the array geometry, and distort the far-field radiation pattern of the array. This paper studies the effects of blockages on the far-field radiation pattern of linear arrays and proposes several array diagnosis techniques for millimeter wave antenna arrays. The proposed techniques jointly estimate the locations of the blocked antennas and the induced attenuation and phase-shifts given knowledge of the angles of arrival/departure. Numerical results show that the proposed techniques provide satisfactory results in terms of fault detection with reduced number of measurements (diagnosis time) provided that the number of blockages is small compared to the array size.

Modelling of the thermal parameters of high-power linear laser-diode arrays. Two-dimensional transient model

International Nuclear Information System (INIS)

Bezotosnyi, V V; Kumykov, Kh Kh

1998-01-01

A two-dimensional transient thermal model of an injection laser is developed. This model makes it possible to analyse the temperature profiles in pulsed and cw stripe lasers with an arbitrary width of the stripe contact, and also in linear laser-diode arrays. This can be done for any durations and repetition rates of the pump pulses. The model can also be applied to two-dimensional laser-diode arrays operating quasicontinuously. An analysis is reported of the influence of various structural parameters of a diode array on the thermal regime of a single laser. The temperature distributions along the cavity axis are investigated for different variants of mounting a crystal on a heat sink. It is found that the temperature drop along the cavity length in cw and quasi-cw laser diodes may exceed 20%. (lasers)

Solar photovoltaic water pumping system using a new linear actuator

OpenAIRE

Andrada Gascón, Pedro; Castro, Javier

2007-01-01

In this paper a photovoltaic solar pumping system using a new linear actuator is presented. This linear actuator is a double-sided flat two-phase variable-reluctance linear stepper motor that moves a piston-type water pump with the help of a rope, a pulley and a counterweight. The entire actuator pump ensemble is controlled by a simple electronic unit that manages the electric power generated by a photovoltaic array. The proposed system is suitable for rural communities in developing...

Phased Array Noise Source Localization Measurements Made on a Williams International FJ44 Engine

Science.gov (United States)

Podboy, Gary G.; Horvath, Csaba

2010-01-01

A 48-microphone planar phased array system was used to acquire noise source localization data on a full-scale Williams International FJ44 turbofan engine. Data were acquired with the array at three different locations relative to the engine, two on the side and one in front of the engine. At the two side locations the planar microphone array was parallel to the engine centerline; at the front location the array was perpendicular to the engine centerline. At each of the three locations, data were acquired at eleven different engine operating conditions ranging from engine idle to maximum (take off) speed. Data obtained with the array off to the side of the engine were spatially filtered to separate the inlet and nozzle noise. Tones occurring in the inlet and nozzle spectra were traced to the low and high speed spools within the engine. The phased array data indicate that the Inflow Control Device (ICD) used during this test was not acoustically transparent; instead, some of the noise emanating from the inlet reflected off of the inlet lip of the ICD. This reflection is a source of error for far field noise measurements made during the test. The data also indicate that a total temperature rake in the inlet of the engine is a source of fan noise.

Partially coherent twisted states in arrays of coupled phase oscillators

Energy Technology Data Exchange (ETDEWEB)

Omel' chenko, Oleh E.; Wolfrum, Matthias [Weierstrass Institute, Mohrenstrasse 39, 10117 Berlin (Germany); Laing, Carlo R. [INMS, Massey University, Private Bag 102-904 NSMC, Auckland (New Zealand)

2014-06-15

We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system.

Partially coherent twisted states in arrays of coupled phase oscillators

International Nuclear Information System (INIS)

Omel'chenko, Oleh E.; Wolfrum, Matthias; Laing, Carlo R.

2014-01-01

We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system

Group Lifting Structures For Multirate Filter Banks, II: Linear Phase Filter Banks

Energy Technology Data Exchange (ETDEWEB)

Brislawn, Christopher M [Los Alamos National Laboratory

2008-01-01

The theory of group lifting structures is applied to linear phase lifting factorizations for the two nontrivial classes of two-channel linear phase perfect reconstruction filter banks, the whole-and half-sample symmetric classes. Group lifting structures defined for the reversible and irreversible classes of whole-and half-sample symmetric filter banks are shown to satisfy the hypotheses of the uniqueness theorem for group lifting structures. It follows that linear phase lifting factorizations of whole-and half-sample symmetric filter banks are therefore independent of the factorization methods used to compute them. These results cover the specification of user-defined whole-sample symmetric filter banks in Part 2 of the ISO JPEG 2000 standard.

Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

International Nuclear Information System (INIS)

Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

2012-01-01

Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

Efficient Narrowband Direction of Arrival Estimation Based on a Combination of Uniform Linear/Shirvani-Akbari Arrays

Directory of Open Access Journals (Sweden)

Shahriar Shirvani Moghaddam

2012-01-01

Full Text Available Uniform linear array (ULA geometry does not perform well for direction of arrival (DOA estimation at directions close to the array endfires. Shirvani and Akbari solved this problem by displacing two elements from both ends of the ULA to the top and/or bottom of the array axis. Shirvani-Akbari array (SAA presents a considerable improvement in the DOA estimation of narrowband sources arriving at endfire directions in terms of DOA estimation accuracy and angular resolution. In this paper, all new proposed SAA configurations are modelled and also examined, numerically. In this paper, two well-known DOA estimation algorithms, multiple signal classification (MUSIC and minimum variance distortionless response (MVDR, are used to evaluate the effectiveness of proposed arrays using total root mean square error (RMSE criterion. In addition, two new scenarios are proposed which divide angular search to two parts, directions close to array endfires as well as middle angles. For middle angles, which belong to (−70∘≤≤70∘, ULA is considered, and for endfire angles, the angles which belong to (−90∘≤≤−70∘ and (70∘≤≤90∘, SAA is considered. Simulation results of new proposed scenarios for DOA estimation of narrowband signals show the better performance with lower computational load.

A review of array radars

Science.gov (United States)

Brookner, E.

1981-10-01

Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting (phase-phase steered arrays); arrays steered + or - 60 deg, limited scan arrays, hemispherical coverage, and omnidirectional coverage arrays; array radars steering electronically in only one dimension, either by frequency or by phase steering; and array radar antennas which use no electronic scanning but instead use array antennas for achieving low antenna sidelobes.

A simple uniformity test for ultrasound phased arrays.

Science.gov (United States)

Dudley, Nicholas J; Woolley, Darren J

2016-09-01

It is difficult to test phased array ultrasound transducers for non functioning elements. We aimed to modify a widely performed test to improve its ease and effectiveness for these arrays. A paperclip was slowly moved along the transducer array, with the scanner operating in M-mode, imaging at a fundamental frequency with automatic gain and grey scale adjustment disabled. Non-functioning elements are identified by a dark vertical line in the image. The test was repeated several times for each transducer, looking for consistency of results. 2 transducers, with faults already shown by electronic transducer testing, were used to validate the method. 23 transducers in clinical use were tested. The results of the modified test on the 2 faulty transducers agreed closely with electronic transducer testing results. The test indicated faults in 5 of the 23 transducers in clinical use: 3 with a single failed element and 2 with non-uniform sensitivity. 1 transducer with non-uniform sensitivity had undergone lens repair; the new lens was visibly non-uniform in thickness and further testing showed a reduction in depth of penetration and a loss of elevational focus in comparison with a new transducer. The modified test is capable of detecting non-functioning elements. Further work is required to provide a better understanding of more subtle faults. Copyright © 2016 Associazione Italiana di Fisica Medica. All rights reserved.

Procedure Development and Qualification of the Phased Array Ultrasonic Testing for the Nuclear Power Plant Piping Weld

International Nuclear Information System (INIS)

Yoon, Byung Sik; Yang, Seung Han; Kim, Yong Sik; Lee, Hee Jong

2010-01-01

The manual ultrasonic examination for the nuclear power plant piping welds has been demonstrated by using KPD(Korean Performance Demonstration) generic procedure. For automated ultrasonic examination, there is no generic procedure and it should be qualified by using applicable automated equipment. Until now, most of qualified procedures used pulse-echo technique and there is no qualified procedure using phased array technique. In this study, data acquisition and analysis software were developed and phased-array transducer and wedge were designed to implement phased array technique for nuclear power plant in-service inspection. The developed procedure are qualified for performance demonstration for the flaw detection, length sizing and depth sizing. The qualified procedure will be applied for the field examination in the nuclear power plant piping weld inspection

Sampling phased array, a new technique for ultrasonic signal processing and imaging now available to industry

OpenAIRE

Verkooijen, J.; Bulavinov, A.

2008-01-01

Over the past 10 years the improvement in the field of microelectronics and computer engineering has led to significant advances in ultrasonic signal processing and image construction techniques that are currently being applied to non-destructive material evaluation. A new phased array technique, called "Sampling Phased Array" has been developed in the Fraunhofer Institute for non-destructive testing [1]. It realizes a unique approach of measurement and processing of ultrasonic signals. The s...

A Two-Radius Circular Array Method: Extracting Independent Information on Phase Velocities of Love Waves From Microtremor Records From a Simple Seismic Array

Science.gov (United States)

Tada, T.; Cho, I.; Shinozaki, Y.

2005-12-01

We have invented a Two-Radius (TR) circular array method of microtremor exploration, an algorithm that enables to estimate phase velocities of Love waves by analyzing horizontal-component records of microtremors that are obtained with an array of seismic sensors placed around circumferences of two different radii. The data recording may be done either simultaneously around the two circles or in two separate sessions with sensors distributed around each circle. Both Rayleigh and Love waves are present in the horizontal components of microtremors, but in the data processing of our TR method, all information on the Rayleigh waves ends up cancelled out, and information on the Love waves alone are left to be analyzed. Also, unlike the popularly used frequency-wavenumber spectral (F-K) method, our TR method does not resolve individual plane-wave components arriving from different directions and analyze their "vector" phase velocities, but instead directly evaluates their "scalar" phase velocities --- phase velocities that contain no information on the arrival direction of waves --- through a mathematical procedure which involves azimuthal averaging. The latter feature leads us to expect that, with our TR method, it is possible to conduct phase velocity analysis with smaller numbers of sensors, with higher stability, and up to longer-wavelength ranges than with the F-K method. With a view to investigating the capabilities and limitations of our TR method in practical implementation to real data, we have deployed circular seismic arrays of different sizes at a test site in Japan where the underground structure is well documented through geophysical exploration. Ten seismic sensors were placed equidistantly around two circumferences, five around each circle, with varying combinations of radii ranging from several meters to several tens of meters, and simultaneous records of microtremors around circles of two different radii were analyzed with our TR method to produce

Phased-array vector velocity estimation using transverse oscillations

DEFF Research Database (Denmark)

Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt

2012-01-01

.79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations......, but with a poorer performance compared with a 128-element transducer. The simulation and experimental results demonstrate that the TO method is suitable for use in conjunction with a phased-array transducer, and that 2-D vector velocity estimation is possible down to a depth of 15 cm....

Non-linear elastic thermal stress analysis with phase changes

International Nuclear Information System (INIS)

Amada, S.; Yang, W.H.

1978-01-01

The non-linear elastic, thermal stress analysis with temperature induced phase changes in the materials is presented. An infinite plate (or body) with a circular hole (or tunnel) is subjected to a thermal loading on its inner surface. The peak temperature around the hole reaches beyond the melting point of the material. The non-linear diffusion equation is solved numerically using the finite difference method. The material properties change rapidly at temperatures where the change of crystal structures and solid-liquid transition occur. The elastic stresses induced by the transient non-homogeneous temperature distribution are calculated. The stresses change remarkably when the phase changes occur and there are residual stresses remaining in the plate after one cycle of thermal loading. (Auth.)

Synthesis of Conformal Phased Antenna Arrays With A Novel Multiobjective Invasive Weed Optimization Algorithm

Science.gov (United States)

Li, Wen Tao; Hei, Yong Qiang; Shi, Xiao Wei

2018-04-01

By virtue of the excellent aerodynamic performances, conformal phased arrays have been attracting considerable attention. However, for the synthesis of patterns with low/ultra-low sidelobes of the conventional conformal arrays, the obtained dynamic range ratios of amplitude excitations could be quite high, which results in stringent requirements on various error tolerances for practical implementation. Time-modulated array (TMA) has the advantages of low sidelobe and reduced dynamic range ratio requirement of amplitude excitations. This paper takes full advantages of conformal antenna arrays and time-modulated arrays. The active-element-pattern, including element mutual coupling and platform effects, is employed in the whole design process. To optimize the pulse durations and the switch-on instants of the time-modulated elements, multiobjective invasive weed optimization (MOIWO) algorithm based on the nondominated sorting of the solutions is proposed. A S-band 8-element cylindrical conformal array is designed and a S-band 16-element cylindrical-parabolic conformal array is constructed and tested at two different steering angles.

Design of Linear - and Minimum-phase FIR-equalizers

DEFF Research Database (Denmark)

Bysted, Tommy Kristensen; Jensen, K.J.; Gaunholt, Hans

1996-01-01

an error function which is quadratic in the filtercoefficients. The advantage of the quadratic function is the ability to find the optimal coefficients solving a system of linear equations without iterations.The transformation to a minimum-phase equalizer is carried out by homomorphic deconvolution...

DOA and Noncircular Phase Estimation of Noncircular Signal via an Improved Noncircular Rotational Invariance Propagator Method

Directory of Open Access Journals (Sweden)

Xueqiang Chen

2015-01-01

Full Text Available We consider the computationally efficient direction-of-arrival (DOA and noncircular (NC phase estimation problem of noncircular signal for uniform linear array. The key idea is to apply the noncircular propagator method (NC-PM which does not require eigenvalue decomposition (EVD of the covariance matrix or singular value decomposition (SVD of the received data. Noncircular rotational invariance propagator method (NC-RI-PM avoids spectral peak searching in PM and can obtain the closed-form solution of DOA, so it has lower computational complexity. An improved NC-RI-PM algorithm of noncircular signal for uniform linear array is proposed to estimate the elevation angles and noncircular phases with automatic pairing. We reconstruct the extended array output by combining the array output and its conjugated counterpart. Our algorithm fully uses the extended array elements in the improved propagator matrix to estimate the elevation angles and noncircular phases by utilizing the rotational invariance property between subarrays. Compared with NC-RI-PM, the proposed algorithm has better angle estimation performance and much lower computational load. The computational complexity of the proposed algorithm is analyzed. We also derive the variance of estimation error and Cramer-Rao bound (CRB of noncircular signal for uniform linear array. Finally, simulation results are presented to demonstrate the effectiveness of our algorithm.

Phased array concept for the ultrasonic inservice inspection at the spherical bottom of BWR-pressure vessels

International Nuclear Information System (INIS)

Brekow, G.; Wuestenberg, H.; Moehrle, W.; Schulz, E.

1987-01-01

The required enhancement of the integrity assessment of perforated reactor vessel base plates has been achieved by a phased-array concept. This technique improvement is based on the fact that the quantity of individual resonant components is reduced whilst increasing the amount of web regions which fall into the sonic range of the pivoted detector due to the larger apex angle scope which the phased array concept provides. A mathematical model concept was initially developed to determine the acoustic irradiation angle and squiat angle ranges to be detected by the phased-array scanner. A prototype of this device has been constructed and tested with a steel sample possessing different perforations and experimental reflectors in order to assess and optimize the new system. The results of these investigations are presented together with those of an application at the nuclear power station in Brunsbuettel. (orig./DG) [de

Limitations of Phased Array Beamforming in Open Rotor Noise Source Imaging

Science.gov (United States)

Horvath, Csaba; Envia, Edmane; Podboy, Gary G.

2013-01-01

Phased array beamforming results of the F31/A31 historical baseline counter-rotating open rotor blade set were investigated for measurement data taken on the NASA Counter-Rotating Open Rotor Propulsion Rig in the 9- by 15-Foot Low-Speed Wind Tunnel of NASA Glenn Research Center as well as data produced using the LINPROP open rotor tone noise code. The planar microphone array was positioned broadside and parallel to the axis of the open rotor, roughly 2.3 rotor diameters away. The results provide insight as to why the apparent noise sources of the blade passing frequency tones and interaction tones appear at their nominal Mach radii instead of at the actual noise sources, even if those locations are not on the blades. Contour maps corresponding to the sound fields produced by the radiating sound waves, taken from the simulations, are used to illustrate how the interaction patterns of circumferential spinning modes of rotating coherent noise sources interact with the phased array, often giving misleading results, as the apparent sources do not always show where the actual noise sources are located. This suggests that a more sophisticated source model would be required to accurately locate the sources of each tone. The results of this study also have implications with regard to the shielding of open rotor sources by airframe empennages.

A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

Science.gov (United States)

Khachaturian, Mark Haig

2010-01-01

Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

Superconducting-normal phase boundary of quasicrystalline arrays in a magnetic field

International Nuclear Information System (INIS)

Nori, F.; Niu, Q.; Fradkin, E.; Chang, S.

1987-01-01

We study the effect of frustration, induced by a mangnetic field, on the superconducting diamagnetic properties of two-dimensional quasicrystalline arrays. In particular, we calculate the superconducting-normal phase boundary, T/sub c/(H), for several geometries with quasicrystalline order. The agreement between our theoretically obtained phase boundaries and the experimentally obtained ones is very good. We also propose a new way of analytically analyzing the overall and the fine structure of T/sub c/(H) in terms of short- and long-range correlations among tiles

Thermal therapy for breast tumors by using a cylindrical ultrasound phased array with multifocus pattern scanning: a preliminary numerical study

International Nuclear Information System (INIS)

Ho, C-S; Ju, K-C; Cheng, T-Y; Chen, Y-Y; Lin, W-L

2007-01-01

The purpose of this study is to investigate the feasibility of using a 1 MHz cylindrical ultrasound phased array with multifocus pattern scanning to produce uniform heating for breast tumor thermal therapy. The breast was submerged in water and surrounded by the cylindrical ultrasound phased array. A multifocus pattern was generated and electrically scanned by the phased array to enlarge the treatment lesion in single heating. To prevent overheating normal tissues, a large planning target volume (PTV) would be divided into several planes with several subunits on each plane and sequentially treated with a cooling phase between two successive heatings of the subunit. Heating results for different target temperatures (T tgt ), blood perfusion rates and sizes of the PTV have been studied. Furthermore, a superficial breast tumor with different water temperatures was also studied. Results indicated that a higher target temperature would produce a slightly larger thermal lesion, and a higher blood perfusion rate would not affect the heating lesion size but increase the heating time significantly. The acoustic power deposition and temperature elevations in ribs can be minimized by orienting the acoustic beam from the ultrasound phased array approximately parallel to the ribs. In addition, a large acoustic window on the convex-shaped breast surface for the proposed ultrasound phased array and the cooling effect of water would prevent the skin overheating for the production of a lesion at any desired location. This study demonstrated that the proposed cylindrical ultrasound phased array can provide effective heating for breast tumor thermal therapy without overheating the skin and ribs within a reasonable treatment time

SPS-ALPHA: The First Practical Solar Power Satellite via Arbitrarily Large PHased Array

Data.gov (United States)

National Aeronautics and Space Administration — SPS-ALPHA (Solar Power Satellite via Arbitrarily Large Phased Array) is a novel, bio-mimetic approach to the challenge of space solar power. If successful, this...

Phased Array Excitations For Efficient Near Field Wireless Power Transmission

Science.gov (United States)

2016-09-01

channeled to the battery or power plant. Figure 2. WPT System Block Diagram for Battery Charging. Source : [2]. Wireless power transfer has gained...EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION by Sean X. Hong September 2016 Thesis Advisor: David Jenn Second Reader...TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE PHASED ARRAY EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION 5

Phased array inspection of large size forged steel parts

Science.gov (United States)

Dupont-Marillia, Frederic; Jahazi, Mohammad; Belanger, Pierre

2018-04-01

High strength forged steel requires uncompromising quality to warrant advance performance for numerous critical applications. Ultrasonic inspection is commonly used in nondestructive testing to detect cracks and other defects. In steel blocks of relatively small dimensions (at least two directions not exceeding a few centimetres), phased array inspection is a trusted method to generate images of the inside of the blocks and therefore identify and size defects. However, casting of large size forged ingots introduces changes of mechanical parameters such as grain size, the Young's modulus, the Poisson's ratio, and the chemical composition. These heterogeneities affect the wave propagation, and consequently, the reliability of ultrasonic inspection and the imaging capabilities for these blocks. In this context, a custom phased array transducer designed for a 40-ton bainitic forged ingot was investigated. Following a previous study that provided local mechanical parameters for a similar block, two-dimensional simulations were made to compute the optimal transducer parameters including the pitch, width and number of elements. It appeared that depending on the number of elements, backwall reconstruction can generate high amplitude artefacts. Indeed, the large dimensions of the simulated block introduce numerous constructive interferences from backwall reflections which may lead to important artefacts. To increase image quality, the reconstruction algorithm was adapted and promising results were observed and compared with the scattering cone filter method available in the CIVA software.

Replacement of radiography with ultrasonic phased array for feeder tubes in CANDU reactors using ASME code case N-659-2

International Nuclear Information System (INIS)

Simmons, R.; Bower, Q.; Arseneau, S.

2013-01-01

In this paper we will discuss phased array technology for the replacement of radiography on new construction projects in the nuclear industry. Specifically, through the implementation of A.S.M.E. code N-659-2 and MetaPhase phased array services. Phased Array is not considered a new technique on in service welds in the nuclear industry; however it was unprecedented on new construction welds and required significant investment in regulatory approval (C.N.S.C.), technology research and development, regulatory, client and technician training for successful service implementation. This paper will illustrate the abilities and limitations associated in replacing radiography with MetaPhase, as well as the substantial benefits relative to increased production, improved weld quality, enhanced safety and overall project cost savings. (author)

Distributed sensing of ionospheric irregularities with a GNSS receiver array

Science.gov (United States)

Su, Yang; Datta-Barua, Seebany; Bust, Gary S.; Deshpande, Kshitija B.

2017-08-01

We present analysis methods for studying the structuring and motion of ionospheric irregularities at the subkilometer scale sizes that produce L band scintillations. Spaced-receiver methods are used for Global Navigation Satellite System (GNSS) receivers' phase measurements over approximately subkilometer to kilometer length baselines for the first time. The quantities estimated by these techniques are plasma drift velocity, diffraction anisotropy magnitude and orientation, and characteristic velocity. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts through linearization about the estimated values of the state. Five receivers of SAGA, the Scintillation Auroral Global Positioning System (GPS) Array, provide 100 Hz power and phase data for each channel at L1 frequency. The array is sited in the auroral zone at Poker Flat Research Range, Alaska. A case study of a single scintillating satellite observed by the array is used to demonstrate the spaced-receiver and uncertainty estimation process. A second case study estimates drifts as measured by multiple scintillating channels. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30 min period are compared to a collocated incoherent scatter radar and show good agreement in horizontal drift speed and direction during periods of scintillation for which the characteristic velocity is less than the drift velocity.

Sensor Fusion Techniques for Phased-Array Eddy Current and Phased-Array Ultrasound Data

Energy Technology Data Exchange (ETDEWEB)

Arrowood, Lloyd F. [Y-12 National Security Complex, Oak Ridge, TN (United States)

2018-03-15

Sensor (or Data) fusion is the process of integrating multiple data sources to produce more consistent, accurate and comprehensive information than is provided by a single data source. Sensor fusion may also be used to combine multiple signals from a single modality to improve the performance of a particular inspection technique. Industrial nondestructive testing may utilize multiple sensors to acquire inspection data depending upon the object under inspection and the anticipated types of defects that can be identified. Sensor fusion can be performed at various levels of signal abstraction with each having its strengths and weaknesses. A multimodal data fusion strategy first proposed by Heideklang and Shokouhi that combines spatially scattered detection locations to improve detection performance of surface-breaking and near-surface cracks in ferromagnetic metals is shown using a surface inspection example and is then extended for volumetric inspections. Utilizing data acquired from an Olympus Omniscan MX2 from both phased array eddy current and ultrasound probes on test phantoms, single and multilevel fusion techniques are employed to integrate signals from the two modalities. Preliminary results demonstrate how confidence in defect identification and interpretation benefit from sensor fusion techniques. Lastly, techniques for integrating data into radiographic and volumetric imagery from computed tomography are described and results are presented.

FPGA-based electrocardiography (ECG signal analysis system using least-square linear phase finite impulse response (FIR filter

Directory of Open Access Journals (Sweden)

Mohamed G. Egila

2016-12-01

Full Text Available This paper presents a proposed design for analyzing electrocardiography (ECG signals. This methodology employs highpass least-square linear phase Finite Impulse Response (FIR filtering technique to filter out the baseline wander noise embedded in the input ECG signal to the system. Discrete Wavelet Transform (DWT was utilized as a feature extraction methodology to extract the reduced feature set from the input ECG signal. The design uses back propagation neural network classifier to classify the input ECG signal. The system is implemented on Xilinx 3AN-XC3S700AN Field Programming Gate Array (FPGA board. A system simulation has been done. The design is compared with some other designs achieving total accuracy of 97.8%, and achieving reduction in utilizing resources on FPGA implementation.

In-line phase retarder and polarimeter for conversion of linear to circular polarization

Energy Technology Data Exchange (ETDEWEB)

Kortright, J.B.; Smith, N.V.; Denlinger, J.D. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-04-01

An in-line polarimeter including phase retarder and linear polarizer was designed and commissioned on undulator beamline 7.0 for the purpose of converting linear to circular polarization for experiments downstream. In commissioning studies, Mo/Si multilayers at 95 eV were used both as the upstream, freestanding phase retarder and the downstream linear polarized. The polarization properties of the phase retarder were characterized by direct polarimetry and by collecting MCD spectra in photoemission from Gd and other magnetic surfaces. The resonant birefringence of transmission multilayers results from differing distributions of s- and p-component wave fields in the multilayer when operating near a structural (Bragg) interference condition. The resulting phase retardation is especially strong when the interference is at or near the Brewster angle, which is roughly 45{degrees} in the EUV and soft x-ray ranges.

Dual-Polarized Planar Phased Array Analysis for Meteorological Applications

Directory of Open Access Journals (Sweden)

Chen Pang

2015-01-01

Full Text Available This paper presents a theoretical analysis for the accuracy requirements of the planar polarimetric phased array radar (PPPAR in meteorological applications. Among many factors that contribute to the polarimetric biases, four factors are considered and analyzed in this study, namely, the polarization distortion due to the intrinsic limitation of a dual-polarized antenna element, the antenna pattern measurement error, the entire array patterns, and the imperfect horizontal and vertical channels. Two operation modes, the alternately transmitting and simultaneously receiving (ATSR mode and the simultaneously transmitting and simultaneously receiving (STSR mode, are discussed. For each mode, the polarimetric biases are formulated. As the STSR mode with orthogonal waveforms is similar to the ATSR mode, the analysis is mainly focused on the ATSR mode and the impacts of the bias sources on the measurement of polarimetric variables are investigated through Monte Carlo simulations. Some insights of the accuracy requirements are obtained and summarized.

Deep local and regional hyperthermia with annular phased array

International Nuclear Information System (INIS)

Uehara, S.; Omagari, J.; Hata, K.

1989-01-01

33 refractory tumors mainly located in the pelvic cavity after definitive treatment were treated by loco-regional hyperthermia alone (n = 11) or by heat in combination with radiotherapy (n = 22) by annular phased array (APA) manufactured by BSD Corp. Tumors were heated up to more than 42 0 C in 78% of 347 total heat sessions with induction time 22 ± 1 (S.D.) minutes during which those of intra-pelvic organs were elevated up to between 41 and 42 0 C. Tumor response was CR 18%, PR 50% by heat (11.2 ± 1.5 S.D. fractions) combined with radiotherapy (43.8 ± 12.5 S.D. Gy) and by heat alone (8.6 ± 1.3 S.D. fractions) CR 18%, PR 9%. In all heat sessions superficial pain 36%, skin burn (grade 1-2) 12% inside annular array and slight to moderate systemic heat stress 100% were the main adverse reactions we experienced. (orig.)

Choosing processor array configuration by performance modeling for a highly parallel linear algebra algorithm

International Nuclear Information System (INIS)

Littlefield, R.J.; Maschhoff, K.J.

1991-04-01

Many linear algebra algorithms utilize an array of processors across which matrices are distributed. Given a particular matrix size and a maximum number of processors, what configuration of processors, i.e., what size and shape array, will execute the fastest? The answer to this question depends on tradeoffs between load balancing, communication startup and transfer costs, and computational overhead. In this paper we analyze in detail one algorithm: the blocked factored Jacobi method for solving dense eigensystems. A performance model is developed to predict execution time as a function of the processor array and matrix sizes, plus the basic computation and communication speeds of the underlying computer system. In experiments on a large hypercube (up to 512 processors), this model has been found to be highly accurate (mean error ∼ 2%) over a wide range of matrix sizes (10 x 10 through 200 x 200) and processor counts (1 to 512). The model reveals, and direct experiment confirms, that the tradeoffs mentioned above can be surprisingly complex and counterintuitive. We propose decision procedures based directly on the performance model to choose configurations for fastest execution. The model-based decision procedures are compared to a heuristic strategy and shown to be significantly better. 7 refs., 8 figs., 1 tab

Characterization and linear array LA48 Commissioner for measuring the position of the multi leaf collimator; Caracterizacion y comisionado del linear array LA48 para medir el posicionamiento del colimador multilaminas

Energy Technology Data Exchange (ETDEWEB)

Conles Picos, I.; Cenizo de Castro, E.; Aparicio martin, A. R.; Barrio Lazo, F.; Cesteros Morante, M. J.

2011-07-01

The protocol of Quality Control of electron accelerators for medical use of SEFM proposed for multi leaf collimation system (MLC) to verify the positioning of the blades connect. To do this you must find a system with sufficient accuracy and precision and, if possible, easy to assemble and offers real-time results. One of these teams is the Linear Array of PTW-Freiburg (LA48), which consists of a row of 47 ionization chambers, of 0008 cc and 8 mm apart from each other. In this paper, we describe our process of characterization and LA48 commissioner. (Author)

A Multibeam Dual-Band Orthogonal Linearly Polarized Antenna Array for Satellite Communication on the Move

Directory of Open Access Journals (Sweden)

Yi Liu

2015-01-01

Full Text Available The design and simulation of a 10 × 8 multibeam dual-band orthogonal linearly polarized antenna array operating at Ku-band are presented for transmit-receive applications. By using patches with different coupling methods as elements, both perpendicular polarization in 12.25–12.75 GHz band and horizontal polarization in 14.0–14.5 GHz band are realized in a shared antenna aperture. A microstrip Rotman lens is employed as the beamforming network with 7 input ports, which can generate a corresponding number of beams to cover −30°–30° with 5 dB beamwidth along one dimension. This type of multibeam orthogonal linearly polarized planar antenna is a good candidate for satellite communication (SatCom.

Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

Directory of Open Access Journals (Sweden)

Xin Su

2015-01-01

Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

Detection of coffee flavour ageing by solid-phase microextraction/surface acoustic wave sensor array technique (SPME/SAW).

Science.gov (United States)

Barié, Nicole; Bücking, Mark; Stahl, Ullrich; Rapp, Michael

2015-06-01

The use of polymer coated surface acoustic wave (SAW) sensor arrays is a very promising technique for highly sensitive and selective detection of volatile organic compounds (VOCs). We present new developments to achieve a low cost sensor setup with a sampling method enabling the highly reproducible detection of volatiles even in the ppb range. Since the VOCs of coffee are well known by gas chromatography (GC) research studies, the new sensor array was tested for an easy assessable objective: coffee ageing during storage. As reference method these changes were traced with a standard GC/FID set-up, accompanied by sensory panellists. The evaluation of GC data showed a non-linear characteristic for single compound concentrations as well as for total peak area values, disabling prediction of the coffee age. In contrast, the new SAW sensor array demonstrates a linear dependency, i.e. being capable to show a dependency between volatile concentration and storage time. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications

KAUST Repository

Ghaffar, Farhan A.

2015-06-01

The theory and design of a half-mode substrate-integrated waveguide ferrite low-temperature cofired ceramic-based phase shifter are presented in this paper. Unlike typical ferrite-based designs, the biasing is done through embedded windings in a multi-layer substrate that not only obviates the requirement of bulky electromagnets, but also prevents loss of bias fields at the air-to-ferrite interface. The phase shifter is operated in the partially magnetized state of ferrite substrate. Through the combined effect of embedded windings, half-mode waveguide operation, and partially magnetized state, the required bias fields have been reduced by 90% as compared with conventional ferrite-based designs employing electromagnets. A complete analytical model, backed up by electromagnetic simulations and measured results from a prototype, is presented in this paper. The fabricated prototype demonstrates a phase shift of 83.2° at a center frequency of 13.1 GHz and a figure of merit of 83.2°/dB. As a proof-of-concept, the proposed phase shifter design is monolithically integrated with a two-element antenna array to demonstrate a measured beam steering of 30°. The phase shifter design is highly efficient in terms of required bias fields, and it has a small form factor and can be easily integrated with other electronic components and systems. © 1965-2012 IEEE.

PHASED ARRAY FEED CALIBRATION, BEAMFORMING, AND IMAGING

International Nuclear Information System (INIS)

Landon, Jonathan; Elmer, Michael; Waldron, Jacob; Jones, David; Stemmons, Alan; Jeffs, Brian D.; Warnick, Karl F.; Richard Fisher, J.; Norrod, Roger D.

2010-01-01

Phased array feeds (PAFs) for reflector antennas offer the potential for increased reflector field of view and faster survey speeds. To address some of the development challenges that remain for scientifically useful PAFs, including calibration and beamforming algorithms, sensitivity optimization, and demonstration of wide field of view imaging, we report experimental results from a 19 element room temperature L-band PAF mounted on the Green Bank 20 Meter Telescope. Formed beams achieved an aperture efficiency of 69% and a system noise temperature of 66 K. Radio camera images of several sky regions are presented. We investigate the noise performance and sensitivity of the system as a function of elevation angle with statistically optimal beamforming and demonstrate cancelation of radio frequency interference sources with adaptive spatial filtering.

Diamagneto-Dielectric Anisotropic Wide Angle Impedance Matching Layers for Active Phased Arrays

NARCIS (Netherlands)

Silvestri, F.; Cifola, L.; Gerini, G.

2016-01-01

In this paper, we present the full process of designing anisotropic metamaterial (MM) wide angle impedance matching (WAIM) layers. These layers are used to reduce the scan losses that occur in active phased arrays for large scanning angles. Numerical results are provided to show the improvement in

Diamagneto-dielectric anisotropic wide angle impedance matching layers for active phased arrays

NARCIS (Netherlands)

Silvestri, F.; Cifola, L.; Gerini, G.

2016-01-01

In this paper we present the full process of designing anisotropic metamaterial (MM) wide angle impedance matching (WAIM) layers. These layers are used to reduce the scan losses that occur in active phased arrays for large scanning angles. Numerical results are provided to show the improvement in

Ultrasonic Phased Array Techniques for Detection of Flaws of Stud Bolts in Nuclear Power Plants

International Nuclear Information System (INIS)

Lee, Joon Hyun; Choi, Sang Woo

2006-01-01

The reactor vessel body and closure head are fastened with the stud bolt that is one of crucial parts for safety of the reactor vessels in nuclear power plants. It is reported that the stud bolt is often experienced by fatigue cracks initiated at threads. Stud bolts are inspected by the ultrasonic technique during the overhaul periodically for the prevention of failure which leads to radioactive leakage from the nuclear reactor. The conventional ultrasonic inspection for stud bolts was mainly conducted by reflected echo method based on shadow effect. However, in this technique, there were numerous spurious signals reflected from every oblique surfaces of the thread. In this study, ultrasonic phased array technique was applied to investigate detectability of flaws in stud bolts and characteristics of ultrasonic images corresponding to different scanning methods, that is, sector and linear scan. For this purpose, simplified stud bolt specimens with artificial defects of various depths were prepared

Degree-of-Freedom Strengthened Cascade Array for DOD-DOA Estimation in MIMO Array Systems.

Science.gov (United States)

Yao, Bobin; Dong, Zhi; Zhang, Weile; Wang, Wei; Wu, Qisheng

2018-05-14

In spatial spectrum estimation, difference co-array can provide extra degrees-of-freedom (DOFs) for promoting parameter identifiability and parameter estimation accuracy. For the sake of acquiring as more DOFs as possible with a given number of physical sensors, we herein design a novel sensor array geometry named cascade array. This structure is generated by systematically connecting a uniform linear array (ULA) and a non-uniform linear array, and can provide more DOFs than some exist array structures but less than the upper-bound indicated by minimum redundant array (MRA). We further apply this cascade array into multiple input multiple output (MIMO) array systems, and propose a novel joint direction of departure (DOD) and direction of arrival (DOA) estimation algorithm, which is based on a reduced-dimensional weighted subspace fitting technique. The algorithm is angle auto-paired and computationally efficient. Theoretical analysis and numerical simulations prove the advantages and effectiveness of the proposed array structure and the related algorithm.

Blind phase retrieval for aberrated linear shift-invariant imaging systems

International Nuclear Information System (INIS)

Yu, Rotha P; Paganin, David M

2010-01-01

We develop a means to reconstruct an input complex coherent scalar wavefield, given a through focal series (TFS) of three intensity images output from a two-dimensional (2D) linear shift-invariant optical imaging system with unknown aberrations. This blind phase retrieval technique unites two methods, namely (i) TFS phase retrieval and (ii) iterative blind deconvolution. The efficacy of our blind phase retrieval procedure has been demonstrated using simulated data, for a variety of Poisson noise levels.

Feasibility study of flexible phased array ultrasonic technology using irregular surface specimen

International Nuclear Information System (INIS)

Lee, Seung Pyo; Moon, Yong Sik; Jung, Nam Du

2015-01-01

Nuclear power plant contain many dissimilar metal welds that connect carbon steel components with stainless steel pipes using alloy 600 welding materials. Primary water stress corrosion cracks at dissimilar metal welds have been continuously reported around the world. In periodic integrity evaluations, dissimilar metal welds are examined using a generic ultrasonic testing procedure, KPD-UT-10. In this procedure, the gap between the probe and examination surface is limited to 1/32 inch (0.8 mm). It is not easy to test some dissimilar metal welds in Korean plants applying ordinary technology because of their tapered shapes and irregular surface conditions. This paper introduces a method for applying a flexible phased array technology to improve the reliability of ultrasonic testing results for various shapes and surface conditions. The artificial flaws in specimens with irregular surfaces were completely detected using the flexible phased array ultrasonic technology. Therefore, it can be said that the technology is applicable to field examination.

Feasibility study of flexible phased array ultrasonic technology using irregular surface specimen

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung Pyo; Moon, Yong Sik; Jung, Nam Du [NDE Performance Demonstration Team, Korea Hydro and Nuclear Power, Central Research Institute, Daejeon (Korea, Republic of)

2015-02-15

Nuclear power plant contain many dissimilar metal welds that connect carbon steel components with stainless steel pipes using alloy 600 welding materials. Primary water stress corrosion cracks at dissimilar metal welds have been continuously reported around the world. In periodic integrity evaluations, dissimilar metal welds are examined using a generic ultrasonic testing procedure, KPD-UT-10. In this procedure, the gap between the probe and examination surface is limited to 1/32 inch (0.8 mm). It is not easy to test some dissimilar metal welds in Korean plants applying ordinary technology because of their tapered shapes and irregular surface conditions. This paper introduces a method for applying a flexible phased array technology to improve the reliability of ultrasonic testing results for various shapes and surface conditions. The artificial flaws in specimens with irregular surfaces were completely detected using the flexible phased array ultrasonic technology. Therefore, it can be said that the technology is applicable to field examination.

A Tutorial on Optical Feeding of Millimeter-Wave Phased Array Antennas for Communication Applications

Directory of Open Access Journals (Sweden)

Ivan Aldaya

2015-01-01

Full Text Available Given the interference avoidance capacity, high gain, and dynamical reconfigurability, phased array antennas (PAAs have emerged as a key enabling technology for future broadband mobile applications. This is especially important at millimeter-wave (mm-wave frequencies, where the high power consumption and significant path loss impose serious range constraints. However, at mm-wave frequencies the phase and amplitude control of the feeding currents of the PAA elements is not a trivial issue because electrical beamforming requires bulky devices and exhibits relatively narrow bandwidth. In order to overcome these limitations, different optical beamforming architectures have been presented. In this paper we review the basic principles of phased arrays and identify the main challenges, that is, integration of high-speed photodetectors with antenna elements and the efficient optical control of both amplitude and phase of the feeding current. After presenting the most important solutions found in the literature, we analyze the impact of the different noise sources on the PAA performance, giving some guidelines for the design of optically fed PAAs.

An optical tunable filter array based on LCOS phase grating

Science.gov (United States)

Feng, Dong; Wan, Zhujun; Chen, Xu; Yan, Shijia; Luo, Zhixiang

2018-01-01

This paper reports an optical tunable filter array (TFA) based on a LCOS (liquid crystal on silicon) chip. The input broadband optical beam is first dispersed by a bulk grating and then incident on the LCOS chip. The LCOS chip is phase-only modulated and constructed as a dynamic reflective phase grating. The phase modulation is adjusted to meet the Littrow angle for a specified passband wavelength and thus the optical beam corresponding to this wavelength is steered to the output. The input/output optical beams are coupled to optical fibers with a dual-fiber collimator. Four dualfiber collimators are vertically aligned as the inputs/outputs and the pixels of the LCOS chip are vertically allocated as four independent zones. Thus the device can act as a 4-channel TFA, which is assembled and functionally demonstrated.

Bearing Estimation Using Double Frequency Reassignment for a Linear Passive Array

Directory of Open Access Journals (Sweden)

Czarnecki Krzysztof

2017-09-01

Full Text Available The paper demonstrates the use of frequency reassignment for bearing estimation. For this task, signals derived from a linear equispaced passive array are used. The presented method makes use of Fourier transformation based spatial spectrum estimation. It is further developed through the application of two-dimensional reassignment, which leads to obtaining highly concentrated energy distributions in the joint frequency-angle domain and sharp graphical imaging. The introduced method can be used for analysing, a priori, unknown signals of broadband, nonstationary, and/or multicomponent type. For such signals, the direction of arrival is obtained based upon the marginal energy distribution in the angle domain, through searching for arguments of its maxima. In the paper, bearing estimation of three popular types of sonar pulses, including linear and hyperbolic frequency modulated pulses, as well as no frequency modulation at all, is considered. The results of numerical experiments performed in the presence of additive white Gaussian noise are presented and compared to conventional digital sum-delay beamforming performed in the time domain. The root-mean-square error and the peak-to-average power ratio, also known as the crest factor, are introduced in order to estimate, respectively, the accuracy of the methods and the sharpness of the obtained energy distributions in the angle domain.

A characteristics of the small crack evaluation technique by triangle method with phased array UT

International Nuclear Information System (INIS)

Cho, Yong Sang

2005-01-01

Ultrasonic testing is a kind of nondestructive test to detect a crack or discontinuity in material or material surface by sending ultrasound to it. This conventional ultrasonic test has some difficulties to detect crack or inspect material specially in the case of complex-shaped power plant components such as Turbine blade root. Phased array UT system and its application methods for complex shaped power plant components will be a good alternative method which overcome present UT weakness. This study was aimed at developing a new method for finding the crack on material or material structures, and especially for determining the crack length without moving transducer. Especially ultrasonic phased array with electronic scan technique was used in carrying out both sizing and detect ability of crack as its depth and length changes. The response of ultrasonic phased array was analyzed to obtain the special method of determining crack length without moving the transducer and detect-ability of crack minimal length and depth from the material. The result showed a newly developed method for crack length determining is very real method which has its accuracy and verify the effectiveness of method compared to a conventional crack length determining method

Development of phased array UT procedure for crack depth sizing on nickel based alloy weld

International Nuclear Information System (INIS)

Hirasawa, Taiji; Okada, Hisao; Fukutomi, Hiroyuki

2012-01-01

Recently, it is reported that the primary water stress corrosion cracking (PWSCC) has been occurred at the nickel based alloy weld components such as steam generator safe end weld, reactor vessel safe end weld, and so on, in PWR. Defect detection and sizing is important in order to ensure the reliable operation and life extension of nuclear power plants. In the reactor vessel safe end weld, it was impossible to measure crack depth of PWSCC. The crack was detected in the axial direction of the safe end weld. Furthermore, the crack had some features such as shallow, large aspect ratio (ratio of crack depth and length), sharp geometry of crack tip, and so on. Therefore, development and improvement of defect detection and sizing capabilities for ultrasonic inspection technique is required. Phased array UT technique was applied to nickel based alloy weld specimen with SCC cracks. From the experimental results, good accuracy of crack depth sizing by phased array UT for the inside inspection was shown. From these results, UT procedure for crack depth sizing was verified. Therefore, effectiveness of phased array UT for crack depth sizing in the nickel based alloy welds was shown. (author)

Clinical evaluation of phased array multicoil for spine MR imaging

International Nuclear Information System (INIS)

Miller, G.M.; Forbes, G.S.; Onofrio, B.M.; Rasmusson, J.J.

1990-01-01

Often, it is necessary to image the entire spinal canal or cord. Current surface coil technology necessitates a small field of view (FOV) and multiple coil placements, prolonging the examination. The Phased Array Multicoil (General Electric, Milwaukee, Wis) allows for high-resolution imaging of a larger segment of the spinal axis (48 cm), negating the need for multiple coil placements. The purpose of this paper is to determine whether, this technology can produce higher-quality images with equal or better expediency in a high-volume clinical practice. The studies were performed with a modified 1.5-T system (General Electric, Milwaukee, Wis). Multiple small surface coils are electronically linked so that each coil images only a small segment of the spinal column. The individual images are then fused to display one high-resolution 512-matrix image with up to a 48-cm FOV. A variety of four coil arrays were tested, including a 24-cm FOV dedicated cervical coil, 48-cm FOV shaped cervical/thoracic and straight thoracic/lumbar coils, and a six-coil array 75-cm entire spine coil. The images were then evaluated for overall quality, resolution, signal-to-noise ratio, and area of coverage

Switchable Phased Antenna Array with Passive Elements for 5G Mobile Terminals

DEFF Research Database (Denmark)

Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

2017-01-01

In this paper, a reconfigurable phased antenna array system is constructed for the mobile terminals in the context of 5G communication system. The proposed antenna system operates at the resonance frequency of 28 GHz. The reconfigurability of the antenna element is achieved by using a passive slot...

Two-dimensional optical phased array antenna on silicon-on-insulator.

Science.gov (United States)

Van Acoleyen, Karel; Rogier, Hendrik; Baets, Roel

2010-06-21

Optical wireless links can offer a very large bandwidth and can act as a complementary technology to radiofrequency links. Optical components nowadays are however rather bulky. Therefore, we have investigated the potential of silicon photonics to fabricated integrated components for wireless optical communication. This paper presents a two-dimensional phased array antenna consisting of grating couplers that couple light off-chip. Wavelength steering of $0.24 degrees /nm is presented reducing the need of active phase modulators. The needed steering range is $1.5 degrees . The 3dB angular coverage range of these antennas is about $0.007pi sr with a directivity of more than 38dBi and antenna losses smaller than 3dB.

The Applicability of Incoherent Array Processing to IMS Seismic Array Stations

Science.gov (United States)

Gibbons, S. J.

2012-04-01

The seismic arrays of the International Monitoring System for the CTBT differ greatly in size and geometry, with apertures ranging from below 1 km to over 60 km. Large and medium aperture arrays with large inter-site spacings complicate the detection and estimation of high frequency phases since signals are often incoherent between sensors. Many such phases, typically from events at regional distances, remain undetected since pipeline algorithms often consider only frequencies low enough to allow coherent array processing. High frequency phases that are detected are frequently attributed qualitatively incorrect backazimuth and slowness estimates and are consequently not associated with the correct event hypotheses. This can lead to missed events both due to a lack of contributing phase detections and by corruption of event hypotheses by spurious detections. Continuous spectral estimation can be used for phase detection and parameter estimation on the largest aperture arrays, with phase arrivals identified as local maxima on beams of transformed spectrograms. The estimation procedure in effect measures group velocity rather than phase velocity and the ability to estimate backazimuth and slowness requires that the spatial extent of the array is large enough to resolve time-delays between envelopes with a period of approximately 4 or 5 seconds. The NOA, AKASG, YKA, WRA, and KURK arrays have apertures in excess of 20 km and spectrogram beamforming on these stations provides high quality slowness estimates for regional phases without additional post-processing. Seven arrays with aperture between 10 and 20 km (MJAR, ESDC, ILAR, KSRS, CMAR, ASAR, and EKA) can provide robust parameter estimates subject to a smoothing of the resulting slowness grids, most effectively achieved by convolving the measured slowness grids with the array response function for a 4 or 5 second period signal. The MJAR array in Japan recorded high SNR Pn signals for both the 2006 and 2009 North Korea

Fabrication of long linear arrays of plastic optical fibers with squared ends for the use of code mark printing lithography

Science.gov (United States)

Horiuchi, Toshiyuki; Watanabe, Jun; Suzuki, Yuta; Iwasaki, Jun-ya

2017-05-01

Two dimensional code marks are often used for the production management. In particular, in the production lines of liquid-crystal-display panels and others, data on fabrication processes such as production number and process conditions are written on each substrate or device in detail, and they are used for quality managements. For this reason, lithography system specialized in code mark printing is developed. However, conventional systems using lamp projection exposure or laser scan exposure are very expensive. Therefore, development of a low-cost exposure system using light emitting diodes (LEDs) and optical fibers with squared ends arrayed in a matrix is strongly expected. In the past research, feasibility of such a new exposure system was demonstrated using a handmade system equipped with 100 LEDs with a central wavelength of 405 nm, a 10×10 matrix of optical fibers with 1 mm square ends, and a 10X projection lens. Based on these progresses, a new method for fabricating large-scale arrays of finer fibers with squared ends was developed in this paper. At most 40 plastic optical fibers were arranged in a linear gap of an arraying instrument, and simultaneously squared by heating them on a hotplate at 120°C for 7 min. Fiber sizes were homogeneous within 496+/-4 μm. In addition, average light leak was improved from 34.4 to 21.3% by adopting the new method in place of conventional one by one squaring method. Square matrix arrays necessary for printing code marks will be obtained by piling the newly fabricated linear arrays up.

Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling.

Science.gov (United States)

Eckert, Paulo Roberto; Flores Filho, Aly Ferreira; Perondi, Eduardo; Ferri, Jeferson; Goltz, Evandro

2016-03-11

This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator.

Low Frequency Phased Array Application for Crack Detection in Cast Austenitic Piping

International Nuclear Information System (INIS)

Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

2006-01-01

As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address nondestructive examination (NDE) reliability of inservice inspection (ISI) programs, studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effectiveness and reliability of ultrasonic testing (UT) as related to the ISI of primary piping components in US commercial nuclear power plants. This paper describes progress, recent developments and results from an assessment of a portion of the work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner's Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, were used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays were employed in laboratory trials. Results from laboratory studies for assessing detection, localization and length sizing effectiveness are discussed.

Two-dimensional mapping of needle visibility with linear and curved array for ultrasound-guided interventional procedure

Science.gov (United States)

Susanti, Hesty; Suprijanto, Kurniadi, Deddy

2018-02-01

Needle visibility in ultrasound-guided technique has been a crucial factor for successful interventional procedure. It has been affected by several factors, i.e. puncture depth, insertion angle, needle size and material, and imaging technology. The influences of those factors made the needle not always well visible. 20 G needles of 15 cm length (Nano Line, facet) were inserted into water bath with variation of insertion angles and depths. Ultrasound measurements are performed with BK-Medical Flex Focus 800 using 12 MHz linear array and 5 MHz curved array in Ultrasound Guided Regional Anesthesia mode. We propose 3 criteria to evaluate needle visibility, i.e. maximum intensity, mean intensity, and the ratio between minimum and maximum intensity. Those criteria were then depicted into representative maps for practical purpose. The best criterion candidate for representing the needle visibility was criterion 1. Generally, the appearance pattern of the needle from this criterion was relatively consistent, i.e. for linear array, it was relatively poor visibility in the middle part of the shaft, while for curved array, it is relatively better visible toward the end of the shaft. With further investigations, for example with the use of tissue-mimicking phantom, the representative maps can be built for future practical purpose, i.e. as a tool for clinicians to ensure better needle placement in clinical application. It will help them to avoid the "dead" area where the needle is not well visible, so it can reduce the risks of vital structures traversing and the number of required insertion, resulting in less patient morbidity. Those simple criteria and representative maps can be utilized to evaluate general visibility patterns of the needle in vast range of needle types and sizes in different insertion media. This information is also important as an early investigation for future research of needle visibility improvement, i.e. the development of beamforming strategies and

Bose-Einstein condensation and chiral phase transition in linear sigma model

International Nuclear Information System (INIS)

Shu Song; Li Jiarong

2005-01-01

With the linear sigma model, we have studied Bose-Einstein condensation and the chiral phase transition in the chiral limit for an interacting pion system. A μ-T phase diagram including these two phenomena is presented. It is found that the phase plane has been divided into three areas: the Bose-Einstein condensation area, the chiral symmetry broken phase area and the chiral symmetry restored phase area. Bose-Einstein condensation can occur either from the chiral symmetry broken phase or from the restored phase. We show that the onset of the chiral phase transition is restricted in the area where there is no Bose-Einstein condensation

Mutual Coupling Effects for Radar Cross Section (RCS of a Series-Fed Dipole Antenna Array

Directory of Open Access Journals (Sweden)

H. L. Sneha

2012-01-01

Full Text Available The estimation of RCS of a phased array depends on various parameters, namely, array geometry, operational frequency, feed network, mutual coupling between the antenna elements and so fourth. This paper presents the estimation of RCS of linear dipole array with series-feed network by tracing the signal path from the antenna aperture into the feed network. The effect of mutual coupling exhibited by the dipole antenna is considered for three configurations namely, side by side, collinear, and parallel in echelon. It is shown that the mutual coupling affects the antenna pattern (and hence RCS significantly for larger scan angles. Further it is inferred that the RCS of phased array can be optimized by (i reducing the length of the dipole, (ii termination of the isolation port of the coupler with a suitable load, and (iii using suitable amplitude distribution.

Nonequilibriun Dynamic Phases of Driven Vortex Lattices in Superconductors with Periodic Pinning Arrays

Science.gov (United States)

Reichhardt, C.; Olson, C. J.; Nori, F.

1998-03-01

We present results from extensive simulations of driven vortex lattices interacting with periodic pinning arrays. Changing an applied driving force produces an exceptionally rich variety of distinct dynamic phases which include over a dozen well defined plastic flow phases. Transitions between different dynamical phases are marked by sharp jumps in the V(I) curves that coincide with distinct changes in the vortex trajectories and vortex lattice order. A series of dynamical phase diagrams are presented which outline the onset of the different dynamical phases (C. Reichhardt, C.J. Olson, and F. Nori, Phys. Rev. Lett. 78), 2648 (1997); and to be published. Videos are avaliable at http://www-personal.engin.umich.edu/ñori/. Using force balance arguments, several of the phase boundaries can be derived analyticaly.

Innervation zones of fasciculating motor units: observations by a linear electrode array.

Science.gov (United States)

Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E; Rymer, William Z; Zhou, Ping

2015-01-01

This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs.

A Phased Array Approach to Rock Blasting

Energy Technology Data Exchange (ETDEWEB)

Leslie Gertsch; Jason Baird

2006-07-01

A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

A Novel Approach to Beam Steering Using Arrays Composed of Multiple Unique Radiating Modes

Science.gov (United States)

Labadie, Nathan Richard

Phased array antennas have found wide application in both radar and wireless communications systems particularly as implementation costs continue to decrease. The primary advantages of electronically scanned arrays are speed of beam scan and versatility of beamforming compared to mechanically scanned fixed beam antennas. These benefits come at the cost of a few well known design issues including element pattern rolloff and mutual coupling between elements. Our primary contribution to the field of research is the demonstration of significant improvement in phased array scan performance using multiple unique radiating modes. In short, orthogonal radiating modes have minimal coupling by definition and can also be generated with reduced rolloff at wide scan angles. In this dissertation, we present a combination of analysis, full-wave electromagnetic simulation and measured data to support our claims. The novel folded ring resonator (FRR) antenna is introduced as a wideband and multi-band element embedded in a grounded dielectric substrate. Multiple radiating modes of a small ground plane excited by a four element FRR array were also investigated. A novel hemispherical null steering antenna composed of two collocated radiating elements, each supporting a unique radiating mode, is presented in the context of an anti-jam GPS receiver application. Both the antenna aperture and active feed network were fabricated and measured showing excellent agreement with analytical and simulated data. The concept of using an antenna supporting multiple radiating modes for beam steering is also explored. A 16 element hybrid linear phased array was fabricated and measured demonstrating significantly improved scan range and scanned gain compared to a conventional phased array. This idea is expanded to 2 dimensional scanning arrays by analysis and simulation of a hybrid phased array composed of novel multiple mode monopole on patch antenna sub-arrays. Finally, we fabricated and

Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

Science.gov (United States)

Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

2016-07-01

Modern multi-mode active phased array radars require highly efficient radar control system for hassle free real time radar operation. The requirement comes due to the distributed architecture of the active phased array radar, where each antenna element in the array is connected to a dedicated Transmit-Receive (TR) module. Controlling the TR modules, which are generally few hundreds in number, and functioning them in synchronisation, is a huge task during real time radar operation and should be handled with utmost care. Indian MST Radar, located at NARL, Gadanki, which is established during early 90's, as an outcome of the middle atmospheric program, is a remote sensing instrument for probing the atmosphere. This radar has a semi-active array, consisting of 1024 antenna elements, with limited beam steering, possible only along the principle planes. To overcome the limitations and difficulties, the radar is being augmented into fully active phased array, to accomplish beam agility and multi-mode operations. Each antenna element is excited with a dedicated 1 kW TR module, located in the field and enables to position the radar beam within 20° conical volume. A multi-channel receiver makes the radar to operate in various modes like Doppler Beam Swinging (DBS), Spaced Antenna (SA), Frequency Domain Interferometry (FDI) etc. Present work describes the real-time radar control (RC) system for the above described active phased array radar. The radar control system consists of a Spartan 6 FPGA based Timing and Control Signal Generator (TCSG), and a computer containing the software for controlling all the subsystems of the radar during real-time radar operation and also for calibrating the radar. The main function of the TCSG is to generate the control and timing waveforms required for various subsystems of the radar. Important components of the RC system software are (i) TR module configuring software which does programming, controlling and health parameter monitoring of the

Critical linear thermal expansion in the smectic-A phase near the nematic-smectic phase transition.

Science.gov (United States)

Anesta, E; Iannacchione, G S; Garland, C W

2004-10-01

Recent high-resolution x-ray investigations of the smectic- A (SmA) phase near the nematic-to-SmA transition provide information about the critical behavior of the linear thermal expansion coefficient alpha// parallel to the director. Combining such data with available volume thermal expansion alpha(V) data yields the in-plane linear expansion coefficient alpha(perpendicular) . The critical behaviors of alpha// and alpha(perpendicular) are the same as those for alpha(V) and the heat capacity Cp. However, for any given liquid crystal, alpha//(crit) and alpha(perpendicular)(crit) differ in sign. Furthermore, the quantity alpha// (crit) is positive for SmAd partial bilayer smectics, while it is negative for nonpolar SmAm monomeric smectics. This feature is discussed in terms of the molecular structural aspects of these smectic phases.

Enhanced linear-array photoacoustic beamforming using modified coherence factor

Science.gov (United States)

Mozaffarzadeh, Moein; Yan, Yan; Mehrmohammadi, Mohammad; Makkiabadi, Bahador

2018-02-01

Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound imaging and the contrast of optical imaging. For linear-array PAI, a beamformer can be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamformer leads to low-resolution images as well as high sidelobes due to nondesired contribution of off-axis signals. Coherence factor (CF) is a weighting method in which each pixel of the reconstructed image is weighted, based on the spatial spectrum of the aperture, to mainly improve the contrast. We demonstrate that the numerator of the formula of CF contains a DAS algebra and propose the use of a delay-multiply-and-sum beamformer instead of the available DAS on the numerator. The proposed weighting technique, modified CF (MCF), has been evaluated numerically and experimentally compared to CF. It was shown that MCF leads to lower sidelobes and better detectable targets. The quantitative results of the experiment (using wire targets) show that MCF leads to for about 45% and 40% improvement, in comparison with CF, in the terms of signal-to-noise ratio and full-width-half-maximum, respectively.

Transverse phase-locking in fully frustrated Josephson junction arrays: A new type of fractional giant steps

International Nuclear Information System (INIS)

Marconi, Veronica I.; Kolton, Alejandro B.; Dominguez, Daniel; Gronbech-Jensen, Niels

2003-05-01

We study, analytically and numerically, phase locking of driven vortex lattices in fully-frustrated Josephson junction arrays at zero temperature. We consider the case when an ac current is applied perpendicular to a dc current. We observe phase locking, steps in the current-voltage characteristics, with a dependence on external ac-drive amplitude and frequency qualitatively different from the Shapiro steps, observed when the ac and dc currents are applied in parallel. Further, the critical current increases with increasing transverse ac-drive amplitude, while it decreases for longitudinal ac-drive. The critical current and the phase-locked current step width, increase quadratically with (small) amplitudes of the ac-drive. For larger amplitudes of the transverse ac-signal, we find windows where the critical current is hysteretic, and windows where phase locking is suppressed due to dynamical instabilities. We characterize the dynamical states around the phase-locking interference condition in the IV curve with voltage noise, Lyapunov exponents and Poincare sections. We find that zero temperature phase-locking behavior in large fully frustrated arrays is well described by an effective four plaquette model. (author)

Simulation and experiment for depth sizing of cracks in anchor bolts by ultrasonic phased array technology

Science.gov (United States)

Lin, Shan

2018-04-01

There have been lots of reports about the occurrence of cracks in bolts in aging nuclear and thermal power plants. Sizing of such cracks is crucial for assessing the integrity of bolts. Currently, hammering and visual tests are used to detect cracks in bolts. However, they are not applicable for sizing cracks. Although the tip diffraction method is well known as a crack sizing technique, reflection echoes from threads make it difficult to apply this technique to bolts. This paper addresses a method for depth sizing of cracks in bolts by means of ultrasonic phased array technology. Numerical results of wave propagation in bolts by the finite element method (FEM) shows that a peak associated within the vicinity of a crack tip can be observed in the curve of echo intensity versus refraction angle for deep cracks. The refraction angle with respect to this peak decreases as crack depth increases. Such numerical results are verified by experiments on bolt specimens that have electrical discharge machining notches or fatigue cracks with different depths. In the experiment, a 10-MHz linear array probe is used. Depth of cracks in bolts using the refraction angle associated with the peak is determined and compared to actual depths. The comparison shows that accurately determining a crack depth from the inspection results is possible.

Phase and Frequency Control of Laser Arrays for Pulse Synthesis

Science.gov (United States)

2015-01-02

SUBTITLE Phase and Frequency Control of Laser Arrays for Pulse Synthesis 875 North Randolph Street Arlington VA 22203-1768 5a. CONTRACT NUMBER...Hachtel, M. Gillette, J. Barkeloo, E. Clements, S. Bali , B. Unks, N. Proite, D. Yavuz, P. Martin, J. Thorn, and D. Steck, Am. J. Phys., 82, 805 (2014...Opt. 37, 4871-4875 (1998). 17. J. Kangara, A. Hachtel, M. Gillette, J. Barkeloo, E. Clements, S. Bali , B. Unks, N. Proite, D. Yavuz, P. Martin, J

Three-Dimensionally Functionalized Reverse Phase Glycoprotein Array for Cancer Biomarker Discovery and Validation.

Science.gov (United States)

Pan, Li; Aguilar, Hillary Andaluz; Wang, Linna; Iliuk, Anton; Tao, W Andy

2016-11-30

Glycoproteins have vast structural diversity that plays an important role in many biological processes and have great potential as disease biomarkers. Here, we report a novel functionalized reverse phase protein array (RPPA), termed polymer-based reverse phase glycoprotein array (polyGPA), to capture and profile glycoproteomes specifically, and validate glycoproteins. Nitrocellulose membrane functionalized with globular hydroxyaminodendrimers was used to covalently capture preoxidized glycans on glycoproteins from complex protein samples such as biofluids. The captured glycoproteins were subsequently detected using the same validated antibodies as in RPPA. We demonstrated the outstanding specificity, sensitivity, and quantitative capabilities of polyGPA by capturing and detecting purified as well as endogenous α-1-acid glycoprotein (AGP) in human plasma. We further applied quantitative N-glycoproteomics and the strategy to validate a panel of glycoproteins identified as potential biomarkers for bladder cancer by analyzing urine glycoproteins from bladder cancer patients or matched healthy individuals.

Model Building of Photovoltaic Array with MPPT Function and Research on Single Phase Grid Connected

Directory of Open Access Journals (Sweden)

Li Zhengzhou

2016-01-01

Full Text Available With the continued development of solar photovoltaic technology, research on distributed grid connected photovoltaic system has become a research focus in the field of photovoltaic grid power plant and the computer simulation technology is an effective technology means in the study. On the basis of the photovoltaic array output characteristic equation, the photovoltaic array maximum power control simulation model based on M function is established by using MATLAB/Simulink and the simulation model of single phase grid connected photovoltaic array is proposed. It overcomes the shortcomings of the process of building the model of the PV array by using Simulink component library and provides the basic guarantee for the realization of system simulation, guiding theory research and system design.

A Small Ku-Band Polarization Tracking Active Phased Array for Mobile Satellite Communications

Directory of Open Access Journals (Sweden)

Wei Shi

2013-01-01

Full Text Available A compact polarization tracking active phased array for Ku-band mobile satellite signal reception is presented. In contrast with conventional mechanically tracking antennas, the approach presented here meets the requirements of beam tracking and polarization tracking simultaneously without any servo components. The two-layer stacked square patch fed by two probes is used as antenna element. The impedance bandwidth of 16% for the element covers the operating frequency range from 12.25 GHz to 12.75 GHz. In the presence of mutual coupling, the dimensional parameters for each element of the small 7 × 7 array are optimized during beam scanning and polarization tracking. The compact polarization tracking modules based on the low-temperature cofired ceramic (LTCC system-in-package (SiP technology are proposed. A small active phased array prototype with the size of 120 mm (length × 120 mm (width × 55 mm (height is developed. The measured polarization tracking patterns of the prototype are given. The polarization tracking beam can be steered in the elevation up to 50°. The gain of no less than 16.0 dBi and the aperture efficiency of more than 50% are obtained. The measured and simulated polarization tracking patterns agreed well.

Ambiguity Resolution for Phase-Based 3-D Source Localization under Fixed Uniform Circular Array.

Science.gov (United States)

Chen, Xin; Liu, Zhen; Wei, Xizhang

2017-05-11

Under fixed uniform circular array (UCA), 3-D parameter estimation of a source whose half-wavelength is smaller than the array aperture would suffer from a serious phase ambiguity problem, which also appears in a recently proposed phase-based algorithm. In this paper, by using the centro-symmetry of UCA with an even number of sensors, the source's angles and range can be decoupled and a novel algorithm named subarray grouping and ambiguity searching (SGAS) is addressed to resolve angle ambiguity. In the SGAS algorithm, each subarray formed by two couples of centro-symmetry sensors can obtain a batch of results under different ambiguities, and by searching the nearest value among subarrays, which is always corresponding to correct ambiguity, rough angle estimation with no ambiguity is realized. Then, the unambiguous angles are employed to resolve phase ambiguity in a phase-based 3-D parameter estimation algorithm, and the source's range, as well as more precise angles, can be achieved. Moreover, to improve the practical performance of SGAS, the optimal structure of subarrays and subarray selection criteria are further investigated. Simulation results demonstrate the satisfying performance of the proposed method in 3-D source localization.

On the chiral phase transition in the linear sigma model

International Nuclear Information System (INIS)

Tran Huu Phat; Nguyen Tuan Anh; Le Viet Hoa

2003-01-01

The Cornwall- Jackiw-Tomboulis (CJT) effective action for composite operators at finite temperature is used to investigate the chiral phase transition within the framework of the linear sigma model as the low-energy effective model of quantum chromodynamics (QCD). A new renormalization prescription for the CJT effective action in the Hartree-Fock (HF) approximation is proposed. A numerical study, which incorporates both thermal and quantum effect, shows that in this approximation the phase transition is of first order. However, taking into account the higher-loop diagrams contribution the order of phase transition is unchanged. (author)

Automated Array Assembly, Phase 2. Quarterly technical progress report, April-June 1979

Energy Technology Data Exchange (ETDEWEB)

Carbajal, B.G.

1979-07-01

The Automated Array Assembly Task, Phase 2 of the Low Cost Solar Array (LSA) Project is a process development task. This contract provides for the fabrication of modules from large area Tandem Junction Cells (TJC). The key activities in this contract effort are (a) Large Area TJC including cell design, process verification and cell fabrication and (b) Tandem Junction Module (TJM) including definition of the cell-module interfaces, substrate fabrication, interconnect fabrication and module assembly. The overall goal is to advance solar cell module process technology to meet the 1986 goal of a production capability of 500 megawatts per year at a cost of less than $500 per peak kilowatt. This contract will focus on the Tandem Junction Module process. During this quarter, effort was focused on design and process verification. The large area TJC design was completed and the design verification was completed. Process variation experiments led to refinements in the baseline TJC process. Formed steel substrates were porcelainized. Cell array assembly techniques using infrared soldering are being checked out. Dummy cell arrays up to 5 cell by 5 cell have been assembled using all backside contacts.

Design of photonic phased array switches using nano electromechanical systems on silicon-on-insulator integration platform

Science.gov (United States)

Hussein, Ali Abdulsattar

This thesis presents an introduction to the design and simulation of a novel class of integrated photonic phased array switch elements. The main objective is to use nano-electromechanical (NEMS) based phase shifters of cascaded under-etched slot nanowires that are compact in size and require a small amount of power to operate them. The structure of the switch elements is organized such that it brings the phase shifting elements to the exterior sides of the photonic circuits. The transition slot couplers, used to interconnect the phase shifters, are designed to enable biasing one of the silicon beams of each phase shifter from an electrode located at the side of the phase shifter. The other silicon beam of each phase shifter is biased through the rest of the silicon structure of the switch element, which is taken as a ground. Phased array switch elements ranging from 2x2 up to 8x8 multiple-inputs/multiple-outputs (MIMO) are conveniently designed within reasonable footprints native to the current fabrication technologies. Chapter one presents the general layout of the various designs of the switch elements and demonstrates their novel features. This demonstration will show how waveguide disturbances in the interconnecting network from conventional switch elements can be avoided by adopting an innovative design. Some possible applications for the designed switch elements of different sizes and topologies are indicated throughout the chapter. Chapter two presents the design of the multimode interference (MMI) couplers used in the switch elements as splitters, combiners and waveguide crossovers. Simulation data and design methodologies for the multimode couplers of interest are detailed in this chapter. Chapter three presents the design and analysis of the NEMS-operated phase shifters. Both simulations and numerical analysis are utilized in the design of a 0°-180° capable NEMS-operated phase shifter. Additionally, the response of some of the designed photonic phased

Dynamic wedge, electron energy and beam profile Q.A. using an ionization chamber linear array

International Nuclear Information System (INIS)

Kenny, M.B.; Todd, S.P.

1996-01-01

Since the introduction of multi-modal linacs the quality assurance workload of a Physical Sciences department has increased dramatically. The advent of dynamic wedges has further complicated matters because of the need to invent accurate methods to perform Q.A. in a reasonable time. We have been using an ionization chamber linear array, the Thebes 7000 TM by Victoreen, Inc., for some years to measure X-ray and electron beam profiles. Two years ago we developed software to perform Q.A. on our dynamic wedges using the array and more recently included a routine to check electron beam energies using the method described by Rosenow, U.F. et al., Med. Phys. 18(1) 19-25. The integrated beam and profile management system has enabled us to maintain a comprehensive quality assurance programme on all our linaccs. Both our efficiency and accuracy have increased to the point where we are able to keep up with the greater number of tests required without an increase in staff or hours spent in quality assurance. In changing the processor from the Z80 of the Thebes console to the 486 of the PC we have also noticed a marked increase in the calibration stability of the array. (author)

Ultra-Wideband Phased Array for Millimeter-Wave 5G and ISM

Science.gov (United States)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2016-01-01

Growing mobile data consumption has prompted the exploration of the millimeter-wave spectrum for large bandwidth, high speed communications. However, the allocated bands are spread across a wide swath of spectrum: fifth generation mobile architecture (5G): 28, 38, 39, 64-71 GHz, as well as Industrial, Scientific, and Medical bands (ISM): 24 and 60 GHz. Moreover, high gain phased arrays are required to overcome the significant path loss associated with these frequencies. Further, it is necessary to incorporate several of these applications in a single, small size and low cost platform. To this end, we have developed a scanning, Ultra-Wideband (UWB) array which covers all 5G, ISM, and other mm-W bands from 24-72 GHz. Critically, this is accomplished using mass-production Printed Circuit Board (PCB) fabrication.

Power and phase monitoring system for the lower hybrid phased array heating system on ATC machine

International Nuclear Information System (INIS)

Reed, B.W.

1975-01-01

A four waveguide phased array slow wave structure has been constructed to couple microwave energy into plasma in the ATC Tokamac at Princeton. Theory has indicated that the coupling of power into the plasma column is a strong function of the imposed fourier spectrum at the antenna aperture. To optimize heating, and to verify theoretical results, a precision amplitude and phase monitoring system has been designed and constructed. The system data output is routed to an IBM 1800 computer where the fourier spectrum in n/sub parallel/ space is computed for discrete increments of time during an RF pulse. Computer output data is used to update the adjustment of transmission line parameters in between pulses

New approach for location of continuously emitting acoustic emission sources by phase-controlled probe arrays

International Nuclear Information System (INIS)

Hoeller, P.; Klein, M.; Waschkies, E.; Deuster, G.

1991-01-01

Usually burst-like acoustic emission (AE) is localized by triangulation. For continuous AE, e.g. from leakages, this method is not feasible. Therefore a new method for localization of continuous AE has been developed. It is based on a phase-controlled probe array which consists of many single sensor elements. The AE signals received by the different sensor elements are delayed according to their time-of-flight differences from the source to the single elements of the receiver array. By choosing special combinations of time differences between the array elements the directivity pattern of the sensitivity of the array can be changed, e.g. rotated in the plane of a large plate. Thus, the source direction can be determined by one array. Some preliminary experiments with an artificial noise source, positioned on a large steel plate, have been performed and have demonstrated the feasibility of this approach. (orig.)

Lifted linear phase filter banks and the polyphase-with-advance representation

Energy Technology Data Exchange (ETDEWEB)

Brislawn, C. M. (Christopher M.); Wohlberg, B. E. (Brendt E.)

2004-01-01

A matrix theory is developed for the noncausal polyphase-with-advance representation that underlies the theory of lifted perfect reconstruction filter banks and wavelet transforms as developed by Sweldens and Daubechies. This theory provides the fundamental lifting methodology employed in the ISO/IEC JPEG-2000 still image coding standard, which the authors helped to develop. Lifting structures for polyphase-with-advance filter banks are depicted in Figure 1. In the analysis bank of Figure 1(a), the first lifting step updates x{sub 0} with a filtered version of x{sub 1} and the second step updates x{sub 1} with a filtered version of x{sub 0}; gain factors 1/K and K normalize the lowpass- and highpass-filtered output subbands. Each of these steps is inverted by the corresponding operations in the synthesis bank shown in Figure 1(b). Lifting steps correspond to upper- or lower-triangular matrices, S{sub i}(z), in a cascade-form decomposition of the polyphase analysis matrix, H{sub a}(z). Lifting structures can also be implemented reversibly (i.e., losslessly in fixed-precision arithmetic) by rounding the lifting updates to integer values. Our treatment of the polyphase-with-advance representation develops an extensive matrix algebra framework that goes far beyond the results of. Specifically, we focus on analyzing and implementing linear phase two-channel filter banks via linear phase lifting cascade schemes. Whole-sample symmetric (WS) and half-sample symmetric (HS) linear phase filter banks are characterized completely in terms of the polyphase-with-advance representation. The theory benefits significantly from a number of new group-theoretic structures arising in the polyphase-with-advance matrix algebra from the lifting factorization of linear phase filter banks.

Nuclear resonant scattering measurements on (57)Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector.

Science.gov (United States)

Kishimoto, S; Mitsui, T; Haruki, R; Yoda, Y; Taniguchi, T; Shimazaki, S; Ikeno, M; Saito, M; Tanaka, M

2014-11-01

We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm(2)) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10(7) cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on (57)Fe.

Development and Calibration of a Field-Deployable Microphone Phased Array for Propulsion and Airframe Noise Flyover Measurements

Science.gov (United States)

Humphreys, William M., Jr.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.; Ravetta, Patricio A.; Johns, Zachary

2016-01-01

A new aeroacoustic measurement capability has been developed consisting of a large channelcount, field-deployable microphone phased array suitable for airframe noise flyover measurements for a range of aircraft types and scales. The array incorporates up to 185 hardened, weather-resistant sensors suitable for outdoor use. A custom 4-mA current loop receiver circuit with temperature compensation was developed to power the sensors over extended cable lengths with minimal degradation of the signal to noise ratio and frequency response. Extensive laboratory calibrations and environmental testing of the sensors were conducted to verify the design's performance specifications. A compact data system combining sensor power, signal conditioning, and digitization was assembled for use with the array. Complementing the data system is a robust analysis system capable of near real-time presentation of beamformed and deconvolved contour plots and integrated spectra obtained from array data acquired during flyover passes. Additional instrumentation systems needed to process the array data were also assembled. These include a commercial weather station and a video monitoring / recording system. A detailed mock-up of the instrumentation suite (phased array, weather station, and data processor) was performed in the NASA Langley Acoustic Development Laboratory to vet the system performance. The first deployment of the system occurred at Finnegan Airfield at Fort A.P. Hill where the array was utilized to measure the vehicle noise from a number of sUAS (small Unmanned Aerial System) aircraft. A unique in-situ calibration method for the array microphones using a hovering aerial sound source was attempted for the first time during the deployment.

Design and characterization of a laterally mounted phased-array transducer breast-specific MRgHIFU device with integrated 11-channel receiver array.

Science.gov (United States)

Payne, A; Merrill, R; Minalga, E; Vyas, U; de Bever, J; Todd, N; Hadley, R; Dumont, E; Neumayer, L; Christensen, D; Roemer, R; Parker, D

2012-03-01

This work presents the design and preliminary evaluation of a new laterally mounted phased-array MRI-guided high-intensity focused ultrasound (MRgHIFU) system with an integrated 11-channel phased-array radio frequency (RF) coil intended for breast cancer treatment. The design goals for the system included the ability to treat the majority of tumor locations, to increase the MR image's signal-to-noise ratio (SNR) throughout the treatment volume and to provide adequate comfort for the patient. In order to treat the majority of the breast volume, the device was designed such that the treated breast is suspended in a 17-cm diameter treatment cylinder. A laterally shooting 1-MHz, 256-element phased-array ultrasound transducer with flexible positioning is mounted outside the treatment cylinder. This configuration achieves a reduced water volume to minimize RF coil loading effects, to position the coils closer to the breast for increased signal sensitivity, and to reduce the MR image noise associated with using water as the coupling fluid. This design uses an 11-channel phased-array RF coil that is placed on the outer surface of the cylinder surrounding the breast. Mechanical positioning of the transducer and electronic steering of the focal spot enable placement of the ultrasound focus at arbitrary locations throughout the suspended breast. The treatment platform allows the patient to lie prone in a face-down position. The system was tested for comfort with 18 normal volunteers and SNR capabilities in one normal volunteer and for heating accuracy and stability in homogeneous phantom and inhomogeneous ex vivo porcine tissue. There was a 61% increase in mean relative SNR achieved in a homogeneous phantom using the 11-channel RF coil when compared to using only a single-loop coil around the chest wall. The repeatability of the system's energy delivery in a single location was excellent, with less than 3% variability between repeated temperature measurements at the same

A novel ultrasonic phased array inspection system to NDT for offshore platform structures

Science.gov (United States)

Wang, Hua; Shan, Baohua; Wang, Xin; Ou, Jinping

2007-01-01

A novel ultrasonic phased array detection system is developed for nondestructive testing (NDT). The purpose of the system is to make acquisition of data in real-time from 64-element ultrasonic phased array transducer, and to enable real- time processing of the acquired data. The system is composed of five main parts: master unit, main board, eight transmit/receive units, a 64-element transducer and an external PC. The system can be used with 64 element transducers, excite 32 elements, receive and sample echo signals form 32 elements simultaneously at 62.5MHz with 8 bit precision. The external PC is used as the user interface showing the real time images and controls overall operation of the system through USB serial link. The use of Universal Serial Bus (USB) improves the transform speed and reduces hardware interface complexity. The program of the system is written in Visual C++.NET and is platform independent.

The Implications of Encoder/Modulator/ Phased Array Designs for Future Broadband LEO Communications

Science.gov (United States)

Vanderaar, Mark; Jensen, Chris A.; Terry, John D.

1997-01-01

In this paper we summarize the effects of modulation and channel coding on the design of wide angle scan, broadband, phased army antennas. In the paper we perform several trade studies. First, we investigate the amplifier back-off requirement as a function of variability of modulation envelope. Specifically, we contrast constant and non-constant envelope modulations, as well as single and multiple carrier schemes. Additionally, we address the issues an(f concerns of using pulse shaping filters with the above modulation types. Second, we quantify the effects of beam steering on the quality of data, recovery using selected modulation techniques. In particular, we show that the frequency response of the array introduces intersymbol interference for broadband signals and that the mode of operation for the beam steering controller may introduce additional burst or random errors. Finally, we show that the encoder/modulator design must be performed in conjunction with the phased array antenna design.

Design of Vivaldi antenna array with end-fire beam steering function for 5G mobile terminals

DEFF Research Database (Denmark)

Ojaroudiparchin, Naser; Shen, Ming; Pedersen, Gert F.

2015-01-01

to form a linear phased array in the edge region (top-side) on a mobile phone PCB. The simulated results show that the antenna has the reflection coefficient (S11) less than -10 dB in the frequency range of 27.4 to 28.6 GHz. The proposed phased array antenna has good gain, efficiency, and 3D beam steering...... characteristics in the entire operation band, which makes it suitable for millimeter-wave 5G communications. In addition, the performance of the antenna in the vicinity of user’s hand has been investigated in this study....

Linearly interpolated sub-symbol optical phase noise suppression in CO-OFDM system.

Science.gov (United States)

Hong, Xuezhi; Hong, Xiaojian; He, Sailing

2015-02-23

An optical phase noise suppression algorithm, LI-SCPEC, based on phase linear interpolation and sub-symbol processing is proposed for CO-OFDM system. By increasing the temporal resolution of carrier phase tracking through dividing one symbol into several sub-blocks, i.e., sub-symbols, inter-carrier-interference (ICI) mitigation is achieved in the proposed algorithm. Linear interpolation is employed to obtain a reliable temporal reference for sub-symbol phase estimation. The new algorithm, with only a few number of sub-symbols (N(B) = 4), can provide a considerably larger laser linewidth tolerance than several other ICI mitigation algorithms as demonstrated by Monte-Carlo simulations. Numerical analysis verifies that the best performance is achieved with an optimal and moderate number of sub-symbols. Complexity analysis shows that the required number of complex-valued multiplications is independent of the number of sub-symbols used in the proposed algorithm.

Comparison of Thrust Characteristics in Pencil Sized Cylinder-type Linear Motors with Different Magnet Arrays(Asia-Pacific Symposium on Applied Electromagnetics and Mechanics (APSAEM08))

OpenAIRE

K., Nakaiwa; A., Yamada; K., Tashiro; H., Wakiwaka; Tamagawa-Seiki Co., Ltd; Shinshu University; Shinshu University; Shinshu University

2009-01-01

From a strong demand on the miniaturization of a chip mounter or a semiconductor device, the thrust improvement considering the magnets arrangement is studied. We accept a core stator with a Halbach type magnet array for a current linear motor. The thrust characteristics are compared with two kinds of mover, a NS magnet array and a Halbach magnet array.

Effect of the plasma production rate on the implosion dynamics of cylindrical wire/fiber arrays with a profiled linear mass

International Nuclear Information System (INIS)

Aleksandrov, V. V.; Mitrofanov, K. N.; Gritsuk, A. N.; Frolov, I. N.; Grabovski, E. V.; Laukhin, Ya. N.

2013-01-01

Results are presented from experimental studies on the implosion of arrays made of wires and metalized fibers under the action of current pulses with an amplitude of up to 3.5 MA at the Angara-5-1 facility. The effect of the parameters of an additional linear mass of bismuth and gold deposited on the wires/fibers is investigated. It is examined how the material of the wires/fibers and the metal coating deposited on them affect the penetration of the plasma with the frozen-in magnetic field into a cylindrical array. Information on the plasma production rate for different metals is obtained by analyzing optical streak images of imploding arrays. The plasma production rate m-dot m for cylindrical arrays made of the kapron fibers coated with bismuth is determined. For the initial array radius of R 0 = 1 cm and discharge current of I = 1 MA, the plasma production rate is found to be m-dot m approx. 0.095 ± 0.015 μg/(cm 2 ns)

Millimeter-wave pseudomorphic HEMT MMIC phased array components for space communications

Science.gov (United States)

Lan, G. L.; Pao, C. K.; Wu, C. S.; Mandolia, G.; Hu, M.; Yuan, S.; Leonard, Regis

1991-01-01

Recent advances in pseudomorphic HEMT MMIC (PMHEMT/MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. This paper describes the development of PMHEMT/MMIC components at Ka-band and V-band. Specifically, the following PMHEMT/MMIC components will be described: power amplifiers at Ka-band; power amplifiers at V-band; and four-bit phase shifters at V-band. For the Ka-band amplifier, 125 mW output power with 5.5 dB gain and 21 percent power added efficiency at 2 dB compression point has been achieved. For the V-band amplifier, 112 mW output power with 6 dB gain and 26 percent power added efficiency has been achieved. And, for the V-band phase shifter, four-bit (45 deg steps) phase shifters with less than 8 dB insertion loss from 61 GHz to 63 GHz will be described.

Recent experiences with ultrasonic inservice inspection systems with phased array probes on spherical bottoms of boiling water reactors

International Nuclear Information System (INIS)

Wustenberg, H.; Brekow, G.; Erhard, A.; Hein, E.

1988-01-01

The special geometry of the spherical bottom of boiling water reactors with control rods and measuring nozzles requires a very special surveillance technique during the in-service inspection. Reside visual inspection an ultrasonic inspection has been established due to the requirements of German authorities. A first application of a new phased array system took place August 1987. The 100% inspection of a spherical bottom had been enabled by the application of phased array probes with electronically controlled skewing angles. The data acquisition had been based on the storage of whole A-scans, which had been pixellized into 256 points. This A-scan storage procedure makes possible the application of a simple and fast algorithm to present the data as TD-(time displacement)-scans. Defect reconstruction by echotomographique approaches are under development. This paper presents the ultrasonic technique applied including the phased array probes, the electronic system, as well as the software package used for the control of the inspection parameters depending on the probe position

A novel, flat, electronically-steered phased array transducer for tissue ablation: preliminary results

International Nuclear Information System (INIS)

Ellens, Nicholas P K; Lucht, Benjamin B C; Gunaseelan, Samuel T; Hudson, John M; Hynynen, Kullervo H

2015-01-01

Flat, λ/2-spaced phased arrays for therapeutic ultrasound were examined in silico and in vitro. All arrays were made by combining modules made of 64 square elements with 1.5 mm inter-element spacing along both major axes. The arrays were designed to accommodate integrated, co-aligned diagnostic transducers for targeting and monitoring. Six arrays of 1024 elements (16 modules) and four arrays of 6144 elements (96 modules) were modelled and compared according to metrics such as peak pressure amplitude, focal size, ability to be electronically-steered far off-axis and grating lobe amplitude. Two 1024 element prototypes were built and measured in vitro, producing over 100 W of acoustic power. In both cases, the simulation model of the pressure amplitude field was in good agreement with values measured by hydrophone. Using one of the arrays, it was shown that the peak pressure amplitude dropped by only 24% and 25% of the on-axis peak pressure amplitude when steered to the edge of the array (40 mm) at depths of 30 mm and 50 mm. For the 6144 element arrays studied in in silico only, similarly high steerability was found: even when steered 100 mm off-axis, the pressure amplitude decrease at the focus was less than 20%, while the maximum pressure grating lobe was only 20%. Thermal simulations indicate that the modules produce more than enough acoustic power to perform rapid ablations at physiologically relevant depths and steering angles. Arrays such as proposed and tested in this study have enormous potential: their high electronic steerability suggests that they will be able to perform ablations of large volumes without the need for any mechanical translation. (paper)

Phased Arrays 1985 Symposium - Proceedings

Science.gov (United States)

1985-08-01

anjl with an1 au~ U lar fy b)eanir. ( mice the 1311 0 ,0 - (a ) ,[ -40.0. -80𔃺 , -90.0 -45.0 0𔃺 45.0 90.0 ANGLE FROM BROADSIDE (DEGREES) aii ia -40,0...Electronic Scanning", RADC-TR-83-128, Dec. 1983. AL) A138808 222 m " ; . . . • " - " - . . . . -" ARRAYS OF COAXIALIY-FED MONOPOLE ELEMENTS IN A PARALLEL...Research Institute Hanscom AFB, MA 01731 Farmingdale, NY 11735 AB ST RAC U Arrays of coaxially-fed monopoles radiating into a parallel plate region

Timed arrays wideband and time varying antenna arrays

CERN Document Server

Haupt, Randy L

2015-01-01

Introduces timed arrays and design approaches to meet the new high performance standards The author concentrates on any aspect of an antenna array that must be viewed from a time perspective. The first chapters briefly introduce antenna arrays and explain the difference between phased and timed arrays. Since timed arrays are designed for realistic time-varying signals and scenarios, the book also reviews wideband signals, baseband and passband RF signals, polarization and signal bandwidth. Other topics covered include time domain, mutual coupling, wideband elements, and dispersion. The auth

32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

Science.gov (United States)

Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

2006-07-01

A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

Numerical Analysis of Ultrasonic Beam Profile Due to the Change of the Number of Piezoelectric Elements for Phased Array Transducer

International Nuclear Information System (INIS)

Choi, Sang Woo; Lee, Joon Hyun

1999-01-01

A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased

Improved Titanium Billet Inspection Sensitivity through Optimized Phased Array Design, Part I: Design Technique, Modeling and Simulation

International Nuclear Information System (INIS)

Lupien, Vincent; Hassan, Waled; Dumas, Philippe

2006-01-01

Reductions in the beam diameter and pulse duration of focused ultrasound for titanium inspections are believed to result in a signal-to-noise ratio improvement for embedded defect detection. It has been inferred from this result that detection limits could be extended to smaller defects through a larger diameter, higher frequency transducer resulting in a reduced beamwidth and pulse duration. Using Continuum Probe Designer TM (Pat. Pending), a transducer array was developed for full coverage inspection of 8 inch titanium billets. The main challenge in realizing a large aperture phased array transducer for billet inspection is ensuring that the number of elements remains within the budget allotted by the driving electronics. The optimization technique implemented by Continuum Probe Designer TM yields an array with twice the aperture but the same number of elements as existing phased arrays for the same application. The unequal area element design was successfully manufactured and validated both numerically and experimentally. Part I of this two-part series presents the design, simulation and modeling steps, while Part II presents the experimental validation and comparative study to multizone

The linear parameters and the decoupling matrix for linearly coupled motion in 6 dimensional phase space

International Nuclear Information System (INIS)

Parzen, G.

1997-01-01

It will be shown that starting from a coordinate system where the 6 phase space coordinates are linearly coupled, one can go to a new coordinate system, where the motion is uncoupled, by means of a linear transformation. The original coupled coordinates and the new uncoupled coordinates are related by a 6 x 6 matrix, R. It will be shown that of the 36 elements of the 6 x 6 decoupling matrix R, only 12 elements are independent. A set of equations is given from which the 12 elements of R can be computed form the one period transfer matrix. This set of equations also allows the linear parameters, the β i , α i , i = 1, 3, for the uncoupled coordinates, to be computed from the one period transfer matrix

Enhanced linear-array photoacoustic beamforming using modified coherence factor.

Science.gov (United States)

Mozaffarzadeh, Moein; Yan, Yan; Mehrmohammadi, Mohammad; Makkiabadi, Bahador

2018-02-01

Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound imaging and the contrast of optical imaging. For linear-array PAI, a beamformer can be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamformer leads to low-resolution images as well as high sidelobes due to nondesired contribution of off-axis signals. Coherence factor (CF) is a weighting method in which each pixel of the reconstructed image is weighted, based on the spatial spectrum of the aperture, to mainly improve the contrast. We demonstrate that the numerator of the formula of CF contains a DAS algebra and propose the use of a delay-multiply-and-sum beamformer instead of the available DAS on the numerator. The proposed weighting technique, modified CF (MCF), has been evaluated numerically and experimentally compared to CF. It was shown that MCF leads to lower sidelobes and better detectable targets. The quantitative results of the experiment (using wire targets) show that MCF leads to for about 45% and 40% improvement, in comparison with CF, in the terms of signal-to-noise ratio and full-width-half-maximum, respectively. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Real-time 3D imaging methods using 2D phased arrays based on synthetic focusing techniques.

Science.gov (United States)

Kim, Jung-Jun; Song, Tai-Kyong

2008-07-01

A fast 3D ultrasound imaging technique using a 2D phased array transducer based on the synthetic focusing method for nondestructive testing or medical imaging is proposed. In the proposed method, each column of a 2D array is fired successively to produce transverse fan beams focused at a fixed depth along a given longitudinal direction and the resulting pulse echoes are received at all elements of a 2D array used. After firing all column arrays, a frame of high-resolution image along a given longitudinal direction is obtained with dynamic focusing employed in the longitudinal direction on receive and in the transverse direction on both transmit and receive. The volume rate of the proposed method can be increased much higher than that of the conventional 2D array imaging by employing an efficient sparse array technique. A simple modification to the proposed method can further increase the volume scan rate significantly. The proposed methods are verified through computer simulations.

The structure of single-phase turbulent flows through closely spaced rod arrays

International Nuclear Information System (INIS)

Hooper, J.D.; Rehme, K.

1983-02-01

The axial and azimuthal turbulence intensity in the rod gap region has been shown, for developed single-phase turbulent flow through parallel rod arrays, to strongly increase with decreasing rod spacing. Two array geometries are reported, one constructed from a rectangular cross-section duct containing four rods and spaced at five p/d or w/d ratios. The second test section, constructed from six rods set in a regular square-pitch array, represented the interior flow region of a large array. The mean axial velocity, wall shear stress variation and axial pressure distribution were measured, together with hot-wire anemometer measurements of the Reynolds stresses. No significant non-zero secondary flow components were detected, using techniques capable of resolving secondary flow velocities to 1% of the local axial velocity. For the lowest p/d ratio of 1.036, cross-correlation measurements showed the presence of an energetic periodic azimuthal turbulent velocity component, correlated over a significant part of the flow area. The negligible contribution of secondary flows to the axial momentum balance, and the large azimuthal turbulent velocity component in the rod gap area, suggest a different mechanism than Reynolds stress gradient driven secondary flows for the turbulent transport process in the rod gap. (orig.) [de

Development of Infrared Phase Closure Capability in the Infrared-Optical Telescope Array (IOTA)

Science.gov (United States)

Traub, Wesley A.

2002-01-01

We completed all major fabrication and testing for the third telescope and phase-closure operation at the Infrared-Optical Telescope Array (IOTA) during this period. In particular we successfully tested the phase-closure operation, using a laboratory light source illuminating the full delay-line optical paths, and using an integrated-optic beam combiner coupled to our Picnic-detector camera. This demonstration is an important and near-final milestone achievement. As of this writing, however, several tasks yet remain, owing to development snags and weather, so the final proof of success, phase-closure observation of a star, is now expected to occur in early 2002, soon after this report has been submitted.

On photonic controlled phase gates

International Nuclear Information System (INIS)

Kieling, K; Eisert, J; O'Brien, J L

2010-01-01

As primitives for entanglement generation, controlled phase gates have a central role in quantum computing. Especially in ideas realizing instances of quantum computation in linear optical gate arrays, a closer look can be rewarding. In such architectures, all effective nonlinearities are induced by measurements. Hence the probability of success is a crucial parameter of such quantum gates. In this paper, we discuss this question for controlled phase gates that implement an arbitrary phase with one and two control qubits. Within the class of post-selected gates in dual-rail encoding with vacuum ancillas, we identify the optimal success probabilities. We construct networks that allow for implementation using current experimental capabilities in detail. The methods employed here appear specifically useful with the advent of integrated linear optical circuits, providing stable interferometers on monolithic structures.

An Ultra-Wideband Millimeter-Wave Phased Array

Science.gov (United States)

Novak, Markus H.; Miranda, Felix A.; Volakis, John L.

2016-01-01

Wideband millimeter-wave arrays are of increasing importance due to their growing use in high data rate systems, including 5G communication networks. In this paper, we present a new class of ultra-wideband millimeter wave arrays that operate from nearly 20 GHz to 90 GHz. The array is based on tightly coupled dipoles. Feeding designs and fabrication challenges are presented, and a method for suppressing feed resonances is provided.

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance