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Sample records for linear periodic arrays

  1. ESPRIT And Uniform Linear Arrays

    Science.gov (United States)

    Roy, R. H.; Goldburg, M.; Ottersten, B. E.; Swindlehurst, A. L.; Viberg, M.; Kailath, T.

    1989-11-01

    Abstract ¬â€?ESPRIT is a recently developed and patented technique for high-resolution estimation of signal parameters. It exploits an invariance structure designed into the sensor array to achieve a reduction in computational requirements of many orders of magnitude over previous techniques such as MUSIC, Burg's MEM, and Capon's ML, and in addition achieves performance improvement as measured by parameter estimate error variance. It is also manifestly more robust with respect to sensor errors (e.g. gain, phase, and location errors) than other methods as well. Whereas ESPRIT only requires that the sensor array possess a single invariance best visualized by considering two identical but other-wise arbitrary arrays of sensors displaced (but not rotated) with respect to each other, many arrays currently in use in various applications are uniform linear arrays of identical sensor elements. Phased array radars are commonplace in high-resolution direction finding systems, and uniform tapped delay lines (i.e., constant rate A/D converters) are the rule rather than the exception in digital signal processing systems. Such arrays possess many invariances, and are amenable to other types of analysis, which is one of the main reasons such structures are so prevalent. Recent developments in high-resolution algorithms of the signal/noise subspace genre including total least squares (TLS) ESPRIT applied to uniform linear arrays are summarized. ESPRIT is also shown to be a generalization of the root-MUSIC algorithm (applicable only to the case of uniform linear arrays of omni-directional sensors and unimodular cisoids). Comparisons with various estimator bounds, including CramerRao bounds, are presented.

  2. 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.

  3. 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

  4. Linear Array Ultrasonic Transducers: Sensitivity and Resolution Study

    International Nuclear Information System (INIS)

    Kramb, V.A.

    2005-01-01

    The University of Dayton Research Institute (UDRI) under contract by the US Air Force has designed and integrated a fully automated inspection system for the inspection of turbine engines that incorporates linear phased array ultrasonic transducers. Phased array transducers have been successfully implemented into weld and turbine blade root inspections where the defect types are well known and characterized. Embedded defects in aerospace turbine engine components are less well defined, however. In order to determine the applicability of linear arrays to aerospace inspections the sensitivity of array transducers to embedded defects in engine materials must be characterized. In addition, the implementation of array transducers into legacy inspection procedures must take into account any differences in sensitivity between the array transducer and that of the single element transducer currently used. This paper discusses preliminary results in a study that compares the sensitivity of linear array and conventional single element transducers to synthetic hard alpha defects in a titanium alloy

  5. Design and Analysis of MEMS Linear Phased Array

    Directory of Open Access Journals (Sweden)

    Guoxiang Fan

    2016-01-01

    Full Text Available A structure of micro-electro-mechanical system (MEMS linear phased array based on “multi-cell” element is designed to increase radiation sound pressure of transducer working in bending vibration mode at high frequency. In order to more accurately predict the resonant frequency of an element, the theoretical analysis of the dynamic equation of a fixed rectangular composite plate and finite element method simulation are adopted. The effects of the parameters both in the lateral and elevation direction on the three-dimensional beam directivity characteristics are comprehensively analyzed. The key parameters in the analysis include the “cell” number of element, “cell” size, “inter-cell” spacing and the number of elements, element width. The simulation results show that optimizing the linear array parameters both in the lateral and elevation direction can greatly improve the three-dimensional beam focusing for MEMS linear phased array, which is obviously different from the traditional linear array.

  6. A novel method to design sparse linear arrays for ultrasonic phased array.

    Science.gov (United States)

    Yang, Ping; Chen, Bin; Shi, Ke-Ren

    2006-12-22

    In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

  7. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes...

  8. Directivity of basic linear arrays

    DEFF Research Database (Denmark)

    Bach, Henning

    1970-01-01

    For a linear uniform array ofnelements, an expression is derived for the directivity as a function of the spacing and the phase constants. The cases of isotropic elements, collinear short dipoles, and parallel short dipoles are included. The formula obtained is discussed in some detail and contour...

  9. Periodic feedback stabilization for linear periodic evolution equations

    CERN Document Server

    Wang, Gengsheng

    2016-01-01

    This book introduces a number of recent advances regarding periodic feedback stabilization for linear and time periodic evolution equations. First, it presents selected connections between linear quadratic optimal control theory and feedback stabilization theory for linear periodic evolution equations. Secondly, it identifies several criteria for the periodic feedback stabilization from the perspective of geometry, algebra and analyses respectively. Next, it describes several ways to design periodic feedback laws. Lastly, the book introduces readers to key methods for designing the control machines. Given its coverage and scope, it offers a helpful guide for graduate students and researchers in the areas of control theory and applied mathematics.

  10. Phononic thermal resistance due to a finite periodic array of nano-scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Trang Nghiêm, T. T.; Chapuis, Pierre-Olivier [Univ. Lyon, CNRS, INSA-Lyon, Université Claude Bernard Lyon 1, CETHIL UMR5008, F-69621 Villeurbanne (France)

    2016-07-28

    The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects that are both subject to reciprocity. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the 5–100 K temperature range. It is observed that the associated thermal conductance has the same temperature dependence as that without phononic filtering.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. Integrated lithography to prepare periodic arrays of nano-objects

    International Nuclear Information System (INIS)

    Sipos, Áron; Szalai, Anikó; Csete, Mária

    2013-01-01

    We present an integrated lithography method to prepare versatile nano-objects with variable shape and nano-scaled substructure, in wavelength-scaled periodic arrays with arbitrary symmetry. The idea is to illuminate colloid sphere monolayers by polarized beams possessing periodic lateral intensity modulations. Finite element method was applied to determine the effects of the wavelength, polarization and angle of incidence of the incoming beam, and to predict the characteristics of nano-objects, which can be fabricated on thin metal layer covered substrates due to the near-field enhancement under silica colloid spheres. The inter-object distance is controlled by varying the relative orientation of the periodic intensity modulation with respect to the silica colloid sphere monolayer. It is shown that illuminating silica colloid sphere monolayers by two interfering beams, linear patterns made of elliptical holes appear in case of linear polarization, while circularly polarized beams result in co-existent rounded objects, as more circular nano-holes and nano-crescents. The size of the nano-objects and their sub-structure is determined by the spheres diameter and by the wavelength. We present various complex plasmonic patterns made of versatile nano-objects that can be uniquely fabricated applying the inherent symmetry breaking possibilities in the integrated lithography method.

  16. 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.

  17. 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...

  18. Wake Vortex Detection: Phased Microphone vs. Linear Infrasonic Array

    Science.gov (United States)

    Shams, Qamar A.; Zuckerwar, Allan J.; Sullivan, Nicholas T.; Knight, Howard K.

    2014-01-01

    Sensor technologies can make a significant impact on the detection of aircraft-generated vortices in an air space of interest, typically in the approach or departure corridor. Current state-of-the art sensor technologies do not provide three-dimensional measurements needed for an operational system or even for wake vortex modeling to advance the understanding of vortex behavior. Most wake vortex sensor systems used today have been developed only for research applications and lack the reliability needed for continuous operation. The main challenges for the development of an operational sensor system are reliability, all-weather operation, and spatial coverage. Such a sensor has been sought for a period of last forty years. Acoustic sensors were first proposed and tested by National Oceanic and Atmospheric Administration (NOAA) early in 1970s for tracking wake vortices but these acoustic sensors suffered from high levels of ambient noise. Over a period of the last fifteen years, there has been renewed interest in studying noise generated by aircraft wake vortices, both numerically and experimentally. The German Aerospace Center (DLR) was the first to propose the application of a phased microphone array for the investigation of the noise sources of wake vortices. The concept was first demonstrated at Berlins Airport Schoenefeld in 2000. A second test was conducted in Tarbes, France, in 2002, where phased microphone arrays were applied to study the wake vortex noise of an Airbus 340. Similarly, microphone phased arrays and other opto-acoustic microphones were evaluated in a field test at the Denver International Airport in 2003. For the Tarbes and Denver tests, the wake trajectories of phased microphone arrays and lidar were compared as these were installed side by side. Due to a built-in pressure equalization vent these microphones were not suitable for capturing acoustic noise below 20 Hz. Our group at NASA Langley Research Center developed and installed an

  19. 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...

  20. 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.

  1. 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).

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Noise reduction in long‐period seismograms by way of array summing

    Science.gov (United States)

    Ringler, Adam; Wilson, David; Storm, Tyler; Marshall, Benjamin T.; Hutt, Charles R.; Holland, Austin

    2016-01-01

    Long‐period (>100  s period) seismic data can often be dominated by instrumental noise as well as local site noise. When multiple collocated sensors are installed at a single site, it is possible to improve the overall station noise levels by applying stacking methods to their traces. We look at the noise reduction in long‐period seismic data by applying the time–frequency phase‐weighted stacking method of Schimmel and Gallart (2007) as well as the phase‐weighted stacking (PWS) method of Schimmel and Paulssen (1997) to four collocated broadband sensors installed in the quiet Albuquerque Seismological Laboratory underground vault. We show that such stacking methods can improve vertical noise levels by as much as 10 dB over the mean background noise levels at 400 s period, suggesting that greater improvements could be achieved with an array involving multiple sensors. We also apply this method to reduce local incoherent noise on horizontal seismic records of the 2 March 2016 Mw 7.8 Sumatra earthquake, where the incoherent noise levels at very long periods are similar in amplitude to the earthquake signal. To maximize the coherency, we apply the PWS method to horizontal data where relative azimuths between collocated sensors are estimated and compared with a simpler linear stack with no azimuthal rotation. Such methods could help reduce noise levels at various seismic stations where multiple high‐quality sensors have been deployed. Such small arrays may also provide a solution to improving long‐period noise levels at Global Seismographic Network stations.

  8. 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.

  9. 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)

  10. 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.

  11. 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...

  12. The investigation of the phase-locking stability in linear arrays of Josephson junctions and arrays closed into a superconducting loop

    International Nuclear Information System (INIS)

    Darula, M.; Seidel, P.; Misanik, B.; Busse, F.; Heinz, E.; Benacka, S.

    1994-01-01

    The phase-locking stability is investigated theoretically in two structures: linear arrays of Josephson junctions shunted by resistive load and arrays closed into superconducting loop. In both cases the quasi-identical junctions are supposed to be in arrays. The stability as a function of spread in Josephson junction parameters as well as a function of other circuit parameters is investigated. Using Floquet theory it is shown that spread in critical currents of Josephson junction limit the stability of phase-locking state. From the simulations it follows that the phase-locking in arrays closed into superconducting loop is more stable against the spread in junction parameters than in the case of linear array of Josephson junctions. (orig.)

  13. 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.

  14. 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.

  15. 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...

  16. 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

  17. Comparison of heating deposition patterns for stacked linear phased array and fixed focus ultrasonic hyperthermia applicators

    International Nuclear Information System (INIS)

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

    1985-01-01

    An ultrasonic stacked linear phased array applicator for hyperthermia has been designed to heat tumors at depths from 5 to 10 cm. The power deposition pattern for this applicator is compared to that for a fixed focus applicator for several different scan paths. The power deposition pattern for the stacked linear phased array shows hot spots that are not observed for the mechanically scanned fixed focus applicator. These hot spots are related to the skewed power deposition pattern resulting from scanning the focus off the center of the linear arrays. The overall performance of the stacked linear phased array applicator is compared to that of a fixed focus applicator

  18. 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.

  19. 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.

  20. Fast photoacoustic imaging system based on 320-element linear transducer array

    International Nuclear Information System (INIS)

    Yin Bangzheng; Xing Da; Wang Yi; Zeng Yaguang; Tan Yi; Chen Qun

    2004-01-01

    A fast photoacoustic (PA) imaging system, based on a 320-transducer linear array, was developed and tested on a tissue phantom. To reconstruct a test tomographic image, 64 time-domain PA signals were acquired from a tissue phantom with embedded light-absorption targets. A signal acquisition was accomplished by utilizing 11 phase-controlled sub-arrays, each consisting of four transducers. The results show that the system can rapidly map the optical absorption of a tissue phantom and effectively detect the embedded light-absorbing target. By utilizing the multi-element linear transducer array and phase-controlled imaging algorithm, we thus can acquire PA tomography more efficiently, compared to other existing technology and algorithms. The methodology and equipment thus provide a rapid and reliable approach to PA imaging that may have potential applications in noninvasive imaging and clinic diagnosis

  1. 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.

  2. Vortex Avalanches with Periodic Arrays of Pinning Sites

    Science.gov (United States)

    Abbas, J.; Heckel, T.; Kakalios, J.

    2001-03-01

    Numerical simulations by Nori and co-workers of dynamical phase transitions for magnetic vortices in type II superconductors when the defects which act as pinning sites are arranged in a periodic array have found a dramatic non-linear relationship between vortex voltage and driving current.2,4 In order to experimentally test the predictions of these simulations, a macroscopic physical analog of an array of flux vortices in the presense of an ordered lattice of pinning sites has been constructed. This simple table-top experimental system consists of conventional household magnets, arranged in an ordered grid (serving as the lattice of fixed pinning centers). A plexiglass sheet is positioned above these fixed magnets, and another collection of magnets (representing the magnetic flux vortices), oriented so that they are attracted to the fixed magnets are placed on top of the sheet. The entire apparatus is then tilted to a given angle (the analog of the driving voltage) and the velocity of the avalanching magnets is recorded using the induced voltage in a pick-up coil. By varying the ratio of movable magnets to fixed pinning magnets, the filling fraction can be adjusted, as can the pinning strength, by adjusting the separation of the plexiglass sheet between the fixed and movable magnets. The velocity of the avalanching magnets as the filling fraction is varied displays a jamming transition, with a non-trivial dependence on the pinning strength of the lattice of fixed magnets below the sheet.

  3. 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.

  4. 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.

  5. 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...

  6. X-ray scattering from periodic arrays of quantum dots

    International Nuclear Information System (INIS)

    Holy, V; Stangl, J; Lechner, R T; Springholz, G

    2008-01-01

    Three-dimensional periodic arrays of self-organized quantum dots in semiconductor multilayers are investigated by high-resolution x-ray scattering. We demonstrate that the statistical parameters of the dot array can be determined directly from the scattering data without performing a numerical simulation of the scattered intensity.

  7. Vortex lattices in different configurations of periodic pinning line-arrays

    International Nuclear Information System (INIS)

    Lima, Clessio Leao S.; Cabral, Leonardo R.E.; Souza Silva, Clecio C. de; Aguiar, J. Albino

    2006-01-01

    The vortex lattice (VL) ground-state configurations are found using Monte Carlo (MC) simulated annealing with a local molecular dynamics (MD) in the London limit. We study the field dependence of the melting temperature for commensurate and incommensurate vortex lattices interacting with different periodic arrays of pinning. We also investigated the proliferation of topological defects and its dependence on the periodic pinning array symmetry and temperature

  8. Transverse impedance of a periodic array of cavities

    Directory of Open Access Journals (Sweden)

    A. V. Fedotov

    1999-06-01

    Full Text Available We examine the transverse impedance of a periodic array of cavities in a beam pipe at high frequency. The calculation is an extension of a previous one for the longitudinal impedance of a periodic array of azimuthally symmetric pillboxes, for which only TM modes were needed. In the present case, we must include TE modes as well. In addition, we extend the applicability of the previous calculation by including an extra term in the coupling kernel so that the results are valid for all values of the ratio of the cavity length to the period of the structure (all values of the ratio of iris thickness to structure period. In spite of the presence of TE modes, we find that the high frequency limit of the transverse impedance is simply (2/ka^{2} times the corresponding limit of the longitudinal impedance, just as it is for the resistive wall impedances, a relation which occurs frequently for azimuthally symmetric structures. Finally, we present numerical results as well as approximate expressions for the impedance per period, valid for all ratios of cavity length to structure period.

  9. RCS estimation of linear and planar dipole phased arrays approximate model

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    In this book, the RCS of a parallel-fed linear and planar dipole array is derived using an approximate method. The signal propagation within the phased array system determines the radar cross section (RCS) of phased array. The reflection and transmission coefficients for a signal at different levels of the phased-in scattering array system depend on the impedance mismatch and the design parameters. Moreover the mutual coupling effect in between the antenna elements is an important factor. A phased array system comprises of radiating elements followed by phase shifters, couplers, and terminating load impedance. These components lead to respective impedances towards the incoming signal that travels through them before reaching receive port of the array system. In this book, the RCS is approximated in terms of array factor, neglecting the phase terms. The mutual coupling effect is taken into account. The dependence of the RCS pattern on the design parameters is analyzed. The approximate model is established as a...

  10. 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.

  11. Coupled mode theory of periodic waveguides arrays

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Chigrin, Dmitry N.

    We apply the scalar coupled mode theory to the case of waveguides array consisting om two periodic waveguides. One of the waveguides is arbitrary shifted along another. A longitudinal shift acts as a parameter in the coupled mode theory. The proposed theory explains peculiarities of modes dispers...... dispersion and transmission in coupled periodic waveguides systems. Analytical results are compared with the numerical ones obtained by the plane wave expansion and FDTD methods....

  12. 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.

  13. 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.

  14. 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.

  15. Periodic linear differential stochastic processes

    NARCIS (Netherlands)

    Kwakernaak, H.

    1975-01-01

    Periodic linear differential processes are defined and their properties are analyzed. Equivalent representations are discussed, and the solutions of related optimal estimation problems are given. An extension is presented of Kailath and Geesey’s [1] results concerning the innovations representation

  16. 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.

  17. 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.

  18. 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.

  19. Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

    Energy Technology Data Exchange (ETDEWEB)

    DeVetter, Brent M.; Bernacki, Bruce E.; Bennett, Wendy D.; Schemer-Kohrn, Alan; Alvine, Kyle J.

    2017-01-01

    Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances—collective charge density oscillations on the surface of the nanoparticle—in the visible spectrum. Here, we focus on the fabrication of periodic arrays of anisotropic plasmonic nanostructures. These half-shell (or nanocup) structures can exhibit additional unique light-bending and polarization dependent optical properties that simple isotropic nanostructures cannot. Researchers are interested in the fabrication of periodic arrays of nanocups for a wide variety of applications such as low-cost optical devices, surface-enhanced Raman scattering, and tamper indication. We present a scalable technique based on colloidal lithography in which it is possible to easily fabricate large periodic arrays of nanocups using spin-coating and self-assembled commercially available polymeric nanospheres. Electron microscopy and optical spectroscopy from the visible to near-IR was performed to confirm successful nanocup fabrication. We conclude with a demonstration of the transfer of nanocups to a flexible, conformal adhesive film.

  20. 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.

  1. 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

  2. Collectively-enhanced optomechanical coupling in periodic arrays of scatterers

    DEFF Research Database (Denmark)

    Xuereb, André; Genes, Claudiu; Dantan, Aurelien Romain

    2013-01-01

    in linear optomechanical coupling strengths between the cavity field and collective motional modes of the array that may be several orders of magnitude larger than is possible with an equivalent reflective ensemble. We describe and interpret these effects in detail and investigate the nature of the scaling...... laws of the coupling strengths for the different transmissive points in various regimes....

  3. 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....

  4. 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.

  5. Three-dimensional vectorial multifocal arrays created by pseudo-period encoding

    Science.gov (United States)

    Zeng, Tingting; Chang, Chenliang; Chen, Zhaozhong; Wang, Hui-Tian; Ding, Jianping

    2018-06-01

    Multifocal arrays have been attracting considerable attention recently owing to their potential applications in parallel optical tweezers, parallel single-molecule orientation determination, parallel recording and multifocal multiphoton microscopy. However, the generation of vectorial multifocal arrays with a tailorable structure and polarization state remains a great challenge, and reports on multifocal arrays have hitherto been restricted either to scalar focal spots without polarization versatility or to regular arrays with fixed spacing. In this work, we propose a specific pseudo-period encoding technique to create three-dimensional (3D) vectorial multifocal arrays with the ability to manipulate the position, polarization state and intensity of each focal spot. We experimentally validated the flexibility of our approach in the generation of 3D vectorial multiple spots with polarization multiplicity and position tunability.

  6. 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.

  7. Voltage splay modes and enhanced phase locking in a modified linear Josephson array

    Science.gov (United States)

    Harris, E. B.; Garland, J. C.

    1997-02-01

    We analyze a modified linear Josephson-junction array in which additional unbiased junctions are used to greatly enhance phase locking. This geometry exhibits strong correlated behavior, with an external magnetic field tuning the voltage splay angle between adjacent Josephson oscillators. The array displays a coherent in-phase mode for f=, where f is the magnetic frustration, while for 0tolerant of critical current disorder approaching 100%. The stability of the array has also been studied by computing Floquet exponents. These exponents are found to be negative for all array lengths, with a 1/N2 dependence, N being the number of series-connected junctions.

  8. 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.

  9. Periodically Driven Array of Single Rydberg Atoms

    Science.gov (United States)

    Basak, Sagarika; Chougale, Yashwant; Nath, Rejish

    2018-03-01

    An array of single Rydberg atoms driven by a temporally modulated atom-field detuning is studied. The periodic modulation effectively modifies the Rabi coupling, leading to unprecedented dynamics in the presence of Rydberg-Rydberg interactions, in particular, blockade enhancement, antiblockades, and state-dependent population trapping. Interestingly, the Schrieffer-Wolf transformation reveals a fundamental process in Rydberg gases, correlated Rabi coupling, which stems from the extended nature of the Rydberg-Rydberg interactions. Also, the correlated coupling provides an alternative depiction for the Rydberg blockade, exhibiting a nontrivial behavior in the presence of periodic modulation. The dynamical localization of a many-body configuration in a driven Rydberg lattice is discussed.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Complementary periodic diffracting metallic nanohole and nanodipole arrays in the mid-infrared range

    Science.gov (United States)

    Ye, Yong-Hong; Zhang, Jia-Yu; Feng Ma, Hui; Yao, Jie; Wang, Xudong

    2012-10-01

    Metallic nanohole arrays and metallic nanodipole arrays are fabricated and experimentally characterized. A complementary response is observed in both transmission and reflection. For the metallic nanohole arrays, a peak (dip) in transmission (reflection) is observed at resonance whereas the metallic nanodipole arrays display a dip (peak) in transmission (reflection). The resonant frequency of both the metallic nanohole arrays and the nanodipole arrays depends on the dipole arm length, the incident angle, and the period. The resonant position of the nanohole arrays matches that of its complement, which means that Babinet's principle nearly holds for these structures in the mid-infrared region.

  15. 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.

  16. Voltage splay modes and enhanced phase locking in a modified linear Josephson array

    International Nuclear Information System (INIS)

    Harris, E.B.; Garland, J.C.

    1997-01-01

    We analyze a modified linear Josephson-junction array in which additional unbiased junctions are used to greatly enhance phase locking. This geometry exhibits strong correlated behavior, with an external magnetic field tuning the voltage splay angle between adjacent Josephson oscillators. The array displays a coherent in-phase mode for f=(1)/(2), where f is the magnetic frustration, while for 0 p (f)=2aV dc /Φ 0 (1-2f). The locked splay modes are found to be tolerant of critical current disorder approaching 100%. The stability of the array has also been studied by computing Floquet exponents. These exponents are found to be negative for all array lengths, with a 1/N 2 dependence, N being the number of series-connected junctions. copyright 1996 The American Physical Society

  17. 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.

  18. 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 ...

  19. 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.

  20. 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

  1. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

    International Nuclear Information System (INIS)

    Chen Sheng-Bing; Wen Ji-Hong; Wang Gang; Wen Xi-Sen

    2013-01-01

    Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches

  2. 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)

  3. 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

  4. 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.

  5. Weak-periodic stochastic resonance in a parallel array of static nonlinearities.

    Directory of Open Access Journals (Sweden)

    Yumei Ma

    Full Text Available This paper studies the output-input signal-to-noise ratio (SNR gain of an uncoupled parallel array of static, yet arbitrary, nonlinear elements for transmitting a weak periodic signal in additive white noise. In the small-signal limit, an explicit expression for the SNR gain is derived. It serves to prove that the SNR gain is always a monotonically increasing function of the array size for any given nonlinearity and noisy environment. It also determines the SNR gain maximized by the locally optimal nonlinearity as the upper bound of the SNR gain achieved by an array of static nonlinear elements. With locally optimal nonlinearity, it is demonstrated that stochastic resonance cannot occur, i.e. adding internal noise into the array never improves the SNR gain. However, in an array of suboptimal but easily implemented threshold nonlinearities, we show the feasibility of situations where stochastic resonance occurs, and also the possibility of the SNR gain exceeding unity for a wide range of input noise distributions.

  6. Enhanced transmission of transverse electric waves through periodic arrays of structured subwavelength apertures

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Peng, Liang; Mortensen, Asger

    2010-01-01

    Transmission through sub-wavelength apertures in perfect metals is expected to be strongly suppressed. However, by structural engineering of the apertures, we numerically demonstrate that the transmission of transverse electric waves through periodic arrays of subwavelength apertures in a thin...... metallic film can be significantly enhanced. Based on equivalent circuit theory analysis, periodic arrays of square structured subwavelength apertures are obtained with a 1900-fold transmission enhancement factor when the side length a of the apertures is 10 times smaller than the wavelength (a/λ =0...

  7. 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.

  8. 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.

  9. An analog of photon-assisted tunneling in a periodically modulated waveguide array

    Science.gov (United States)

    Li, Liping; Luo, Xiaobing; Yang, Xiaoxue; Wang, Mei; Lü, Xinyou; Wu, Ying

    2016-01-01

    We theoretically report an analog of photon-assisted tunneling (PAT) originated from dark Floquet state in a periodically driven lattice array without a static biased potential by studying a three-channel waveguide system in a non-high-frequency regime. This analog of PAT can be achieved by only periodically modulating the top waveguide and adjusting the distance between the bottom and its adjacent waveguide. It is numerically shown that the PAT resonances also exist in the five-channel waveguide system and probably exist in the waveguide arrays with other odd numbers of waveguides, but they will become weak as the number of waveguides increases. With origin different from traditional PAT, this type of PAT found in our work is closely linked to the existence of the zero-energy (dark) Floquet states. It is readily observable under currently accessible experimental conditions and may be useful for controlling light propagation in waveguide arrays. PMID:27767189

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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...

  15. 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...

  16. 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.

  17. 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.

  18. Anomalous transmission through heavily doped conducting polymer films with periodic subwavelength hole array

    Science.gov (United States)

    Matsui, Tatsunosuke; Vardeny, Z. Valy; Agrawal, Amit; Nahata, Ajay; Menon, Reghu

    2006-08-01

    We observed resonantly enhanced (or anomalous transmission) terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF 6 molecules [PPy(PF6)]. The anomalous transmission spectra are in good agreement with a model involving surface plasmon polariton excitations on the film surfaces. We also found that the resonantly enhanced transmission peaks are broader in the exotic metallic PPy(PF6) films compared to those formed in 2D aperture array in regular metallic films such as silver, indicating that the surface plasmon polaritons on the PPy(PF6) film surfaces have higher attenuation.

  19. 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.

  20. Model of tunnelling through periodic array of quantum dots

    Directory of Open Access Journals (Sweden)

    Meynster Dmitry

    2017-01-01

    Full Text Available Several explicitly solvable models of electron tunnelling in a system of single and double two-dimensional periodic arrays of quantum dots with two laterally coupled leads in a homogeneous magnetic field are constructed. First, a model of single layer formed by periodic array of zero-range potentials is described. The Landau operator (the Schrodinger operator with a magnetic field with point-like interactions is the system Hamiltonian. We deal with two types of the layer lattices: square and honeycomb. The periodicity condition gives one an invariance property for the Hamiltonian in respect to magnetic translations group. The consideration of double quantum layer reduces to the replacement of the basic cell for the single layer by a cell including centers of different layers. Two variants of themodel for the double layer are suggested: with direct tunneling between the layers and with the connecting channels (segments in the model between the layers. The theory of self-adjoint extensions of symmetric operators is a mathematical background of the model. The third stage of the construction is the description of leads connection. It is made by the operator extensions theory method too. Electron tunneling from input lead to the output lead through the double quantum layer is described. Energy ranges with extremely small (practically, zero transmission were found. Dependencies of the transmission coefficient (particularly, “zero transmission bands” positions on the magnetic field, the energy of electron and the distance between layers are investigated. The results are compared with the corresponding single-layer transmission.

  1. Periodic solutions of asymptotically linear Hamiltonian systems without twist conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Rong [Coll. of Mathematics and Physics, Nanjing Univ. of Information Science and Tech., Nanjing (China); Dept. of Mathematics, Southeast Univ., Nanjing (China); Zhang Dongfeng [Dept. of Mathematics, Southeast Univ., Nanjing (China)

    2010-05-15

    In dynamical system theory, especially in many fields of applications from mechanics, Hamiltonian systems play an important role, since many related equations in mechanics can be written in an Hamiltonian form. In this paper, we study the existence of periodic solutions for a class of Hamiltonian systems. By applying the Galerkin approximation method together with a result of critical point theory, we establish the existence of periodic solutions of asymptotically linear Hamiltonian systems without twist conditions. Twist conditions play crucial roles in the study of periodic solutions for asymptotically linear Hamiltonian systems. The lack of twist conditions brings some difficulty to the study. To the authors' knowledge, very little is known about the case, where twist conditions do not hold. (orig.)

  2. Stability Analysis for Multi-Parameter Linear Periodic Systems

    DEFF Research Database (Denmark)

    Seyranian, A.P.; Solem, Frederik; Pedersen, Pauli

    1999-01-01

    This paper is devoted to stability analysis of general linear periodic systems depending on real parameters. The Floquet method and perturbation technique are the basis of the development. We start out with the first and higher-order derivatives of the Floquet matrix with respect to problem...

  3. 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.

  4. 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.

  5. Periodic orbits from Δ-modulation of stable linear systems

    OpenAIRE

    Xia, X.; Zinober, A.

    2004-01-01

    The �-modulated control of a single input, discrete time, linear stable system is investigated. The modulation direction is given by cTx where c �Rn/{0} is a given, otherwise arbitrary, vector. We obtain necessary and sufficient conditions for the existence of periodic points of a finite order. Some concrete results about the existence of a certain order of periodic points are also derived. We also study the relationship between certain polyhedra and the periodicity of the �-modulated orb...

  6. 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.

  7. Surface plasmon enhanced absorption and suppressed transmission in periodic arrays of graphene ribbons

    Science.gov (United States)

    Nikitin, A. Yu.; Guinea, F.; Garcia-Vidal, F. J.; Martin-Moreno, L.

    2012-02-01

    Resonance diffraction in the periodic array of graphene microribbons is theoretically studied following a recent experiment [L. Ju , Nature Nanotech.1748-338710.1038/nnano.2011.146 6, 630 (2011)]. Systematic studies over a wide range of parameters are presented. It is shown that a much richer resonant picture would be observable for higher relaxation times of charge carriers: More resonances appear and transmission can be totally suppressed. The comparison with the absorption cross-section of a single ribbon shows that the resonant features of the periodic array are associated with leaky plasmonic modes. The longest-wavelength resonance provides the highest visibility of the transmission dip and has the strongest spectral shift and broadening with respect to the single-ribbon resonance, due to collective effects.

  8. Periodic Arrays of Film-Coupled Cubic Nanoantennas as Tunable Plasmonic Metasurfaces

    Directory of Open Access Journals (Sweden)

    Vassilios Yannopapas

    2015-03-01

    Full Text Available We show theoretically that a two-dimensional periodic array of metallic nanocubes in close proximity to a metallic film acts as a metasurface with tunable absorbance. The presence of a metallic film underneath the array of plasmonic nanocubes leads to an impedance matched plasmonic metasurface enhancing up to 4 times the absorbance of incident radiation, in the spectral region below 500 nm. The absorbance spectrum is weakly dependent on the angle of incidence and state of polarization of incident light a functionality which can find application in thermo-photovoltaics. Our calculations are based on a hybrid layer-multiple-scattering (hLMS method based on a discrete-dipole approximation (DDA/T-matrix point matching method.

  9. 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...

  10. 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.

  11. Periodic motions and grazing in a harmonically forced, piecewise, linear oscillator with impacts

    International Nuclear Information System (INIS)

    Luo, Albert C.J.; Chen Lidi

    2005-01-01

    In this paper, an idealized, piecewise linear system is presented to model the vibration of gear transmission systems. Periodic motions in a generalized, piecewise linear oscillator with perfectly plastic impacts are predicted analytically. The analytical predictions of periodic motion are based on the mapping structures, and the generic mappings based on the discontinuous boundaries are developed. This method for the analytical prediction of the periodic motions in non-smooth dynamic systems can give all possible periodic motions based on the adequate mapping structures. The stability and bifurcation conditions for specified periodic motions are obtained. The periodic motions and grazing motion are demonstrated. This model is applicable to prediction of periodic motion in nonlinear dynamics of gear transmission systems

  12. Mixed models, linear dependency, and identification in age-period-cohort models.

    Science.gov (United States)

    O'Brien, Robert M

    2017-07-20

    This paper examines the identification problem in age-period-cohort models that use either linear or categorically coded ages, periods, and cohorts or combinations of these parameterizations. These models are not identified using the traditional fixed effect regression model approach because of a linear dependency between the ages, periods, and cohorts. However, these models can be identified if the researcher introduces a single just identifying constraint on the model coefficients. The problem with such constraints is that the results can differ substantially depending on the constraint chosen. Somewhat surprisingly, age-period-cohort models that specify one or more of ages and/or periods and/or cohorts as random effects are identified. This is the case without introducing an additional constraint. I label this identification as statistical model identification and show how statistical model identification comes about in mixed models and why which effects are treated as fixed and which are treated as random can substantially change the estimates of the age, period, and cohort effects. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Flow through a cylindrical pipe with a periodic array of fractal orifices

    NARCIS (Netherlands)

    van Melick, P.A.J.; Geurts, Bernardus J.

    2013-01-01

    We apply direct numerical simulation (DNS) of the incompressible Navier–Stokes equations to predict flow through a cylindrical pipe in which a periodic array of orifice plates with a fractal perimeter is mounted. The flow is simulated using a volume penalization immersed boundary method with which

  14. Flow through a cylindrical pipe with a periodic array of fractal orifices

    NARCIS (Netherlands)

    van Melick, P.A.J.; Geurts, B.J.

    2013-01-01

    We apply direct numerical simulation (DNS) of the incompressible Navier-Stokes equations to predict flow through a cylindrical pipe in which a periodic array of orifice plates with a fractal perimeter is mounted. The flow is simulated using a volume penalization immersed boundary method with which

  15. 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.

  16. 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.

  17. Controlling the optical properties of gold nanoparticles periodic arrays by changing their topologic shapes and substrate properties

    International Nuclear Information System (INIS)

    Li Ting; Yu Li; Lu Zhixin; Song Gang; Liu Bin

    2011-01-01

    We investigated the influence of extinction of gold nanoparticles periodic arrays by varying the substrate properties and the shapes of nanoparticles with the full vectorial three dimensional finite difference time domain method. Substrates of different thicknesses and dielectric constants and ten topologically different gold nanostructures including diamond, cycle ring, rectangle ring, pentagon ring, five-pointed star, flower shape, L, Y, T and X shapes are considered. The results show that substrate properties have a significant impact on the extinction spectrum due to coupling of the modes excited in substrates and the one excited by localized surface plasmon. The extinction spectra are changed with the different shapes of nanoparticles periodic array. However, with similar structure particles periodic arrays, the extinction spectra appear similar in the visible regime. Therefore we can find an eligible shape and substrate which can be used in integrated devises.

  18. Transmission of light through periodic arrays of square holes : from a metallic wire mesh to an array of tiny holes

    NARCIS (Netherlands)

    Bravo-Abad, J.; Martin-Moreno, L.; Garcia-Vidal, F.J.; Hendry, E.; Gómez Rivas, J.

    2007-01-01

    A complete landscape is presented of the electromagnetic coupling between square holes forming a two-dimensional periodic array in a metallic film. By combining both experimental and theoretical results along with a first-principles Fano model, we study the crossover between the physics of metallic

  19. Broadband photocurrent enhancement and light-trapping in thin film Si solar cells with periodic Al nanoparticle arrays on the front

    DEFF Research Database (Denmark)

    Uhrenfeldt, C.; Villesen, T. F.; Tetu, A.

    2015-01-01

    Plasmonic resonances in metal nanoparticles are considered candidates for improved thin film Si photovoltaics. In periodic arrays the influence of collective modes can enhance the resonant properties of such arrays. We have investigated the use of periodic arrays of Al nanoparticles placed...... on the front of a thin film Si test solar cell. It is demonstrated that the resonances from the Al nanoparticle array cause a broadband photocurrent enhancement ranging from the ultraviolet to the infrared with respect to a reference cell. From the experimental results as well as from numerical simulations...

  20. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  1. Crystalline and quasi-crystalline patterns in X-Ray diffraction from periodic arrays of quantum dots

    NARCIS (Netherlands)

    Darhuber, A.A.; Holy, V.; Bauer, G.; Wang, P.D.; Song, Y.P.; Sotomayor Torres, C.M.; Holland, M.C.

    1995-01-01

    The structural properties of a square periodic array of quantum dots of a GaAs/AlAs superlattice were studied by x-ray diffractometry. If the azimuthal direction of the primary beam can be expressed by integer Miller indices, the profile is perfectly periodic. However, if its azimuthal orientation

  2. 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)

  3. 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.

  4. H-infinity Control of Linear Systems with Almost Periodic Inputs

    DEFF Research Database (Denmark)

    Larsen, Mikael

    1996-01-01

    In this paper we consider the class of linear, infinitedimensional systems with bounded input and output operators. Wederive and QTR H-infinity type result, formulated for thecase where the input signals are almost periodic in a generalizedsense. Control probelms, for which this result is relevant...

  5. Stationarity and periodicities of linear speed of coronal mass ejection: a statistical signal processing approach

    Science.gov (United States)

    Chattopadhyay, Anirban; Khondekar, Mofazzal Hossain; Bhattacharjee, Anup Kumar

    2017-09-01

    In this paper initiative has been taken to search the periodicities of linear speed of Coronal Mass Ejection in solar cycle 23. Double exponential smoothing and Discrete Wavelet Transform are being used for detrending and filtering of the CME linear speed time series. To choose the appropriate statistical methodology for the said purpose, Smoothed Pseudo Wigner-Ville distribution (SPWVD) has been used beforehand to confirm the non-stationarity of the time series. The Time-Frequency representation tool like Hilbert Huang Transform and Empirical Mode decomposition has been implemented to unearth the underneath periodicities in the non-stationary time series of the linear speed of CME. Of all the periodicities having more than 95% Confidence Level, the relevant periodicities have been segregated out using Integral peak detection algorithm. The periodicities observed are of low scale ranging from 2-159 days with some relevant periods like 4 days, 10 days, 11 days, 12 days, 13.7 days, 14.5 and 21.6 days. These short range periodicities indicate the probable origin of the CME is the active longitude and the magnetic flux network of the sun. The results also insinuate about the probable mutual influence and causality with other solar activities (like solar radio emission, Ap index, solar wind speed, etc.) owing to the similitude between their periods and CME linear speed periods. The periodicities of 4 days and 10 days indicate the possible existence of the Rossby-type waves or planetary waves in Sun.

  6. Resonantly-enhanced transmission through a periodic array of subwavelength apertures in heavily-doped conducting polymer films

    Science.gov (United States)

    Matsui, Tatsunosuke; Vardeny, Z. Valy; Agrawal, Amit; Nahata, Ajay; Menon, Reghu

    2006-02-01

    We observed resonantly-enhanced terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF6 molecules [PPy(PF6)]. The "anomalous transmission" spectra are in good agreement with a model involving surface plasmon polariton excitations on the film surfaces. We also found that the `anomalous transmission' peaks are broader in the exotic metallic PPy (PF6) films compared to those formed in 2D aperture array in regular metallic films such as silver, showing that the surface plasmon polaritons on the PPy (PF6) film surfaces have higher attenuation.

  7. Eigenstates of a particle in an array of hexagons with periodic boundary condition

    Directory of Open Access Journals (Sweden)

    A Nemati

    2013-10-01

    Full Text Available In this paper the problem of a particle in an array of hexagons with periodic boundary condition is solved. Using the projection operators, we categorize eigenfunctions corresponding to each of the irreducible representations of the symmetry group . Based on these results, the Dirichlet and Neumann boundary conditions are discussed.

  8. Doubly Periodic Traveling Waves in a Cellular Neural Network with Linear Reaction

    Directory of Open Access Journals (Sweden)

    Lin JianJhong

    2009-01-01

    Full Text Available Szekeley observed that the dynamic pattern of the locomotion of salamanders can be explained by periodic vector sequences generated by logical neural networks. Such sequences can mathematically be described by "doubly periodic traveling waves" and therefore it is of interest to propose dynamic models that may produce such waves. One such dynamic network model is built here based on reaction-diffusion principles and a complete discussion is given for the existence of doubly periodic waves as outputs. Since there are 2 parameters in our model and 4 a priori unknown parameters involved in our search of solutions, our results are nontrivial. The reaction term in our model is a linear function and hence our results can also be interpreted as existence criteria for solutions of a nontrivial linear problem depending on 6 parameters.

  9. Effective diffusion in time-periodic linear planar flow

    International Nuclear Information System (INIS)

    Indeikina, A.; Chang, H.

    1993-01-01

    It is shown that when a point source of solute is inserted into a time-periodic, unbounded linear planar flow, the large-time, time-average transport of the solute can be described by classical anisotropic diffusion with constant effective diffusion tensors. For a given vorticity and forcing period, elongational flow is shown to be the most dispersive followed by simple shear and rotational flow. Large-time diffusivity along the major axis of the time-average concentration ellipse, whose alignment is predicted from the theory, is shown to increase with vorticity for all flows and decrease with increasing forcing frequency for elongational flow and simple shear. For the interesting case of rotational flow, there exist discrete resonant frequencies where the time-average major diffusivity reaches local maxima equal to the time-average steady flow case with zero forcing frequency

  10. Non-linear second-order periodic systems with non-smooth potential

    Indian Academy of Sciences (India)

    In this paper we study second order non-linear periodic systems driven by the ordinary vector -Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth conditions on ...

  11. Non-linear second-order periodic systems with non-smooth potential

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. In this paper we study second order non-linear periodic systems driven by the ordinary vector p-Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth ...

  12. 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

  13. 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)

  14. 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.

  15. 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.

  16. 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.

  17. Active cancellation of probing in linear dipole phased array

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2015-01-01

    In this book, a modified improved LMS algorithm is employed for weight adaptation of dipole array for the generation of beam pattern in multiple signal environments. In phased arrays, the generation of adapted pattern according to the signal scenario requires an efficient adaptive algorithm. The antenna array is expected to maintain sufficient gain towards each of the desired source while at the same time suppress the probing sources. This cancels the signal transmission towards each of the hostile probing sources leading to active cancellation. In the book, the performance of dipole phased array is demonstrated in terms of fast convergence, output noise power and output signal-to-interference-and noise ratio. The mutual coupling effect and role of edge elements are taken into account. It is established that dipole array along with an efficient algorithm is able to maintain multilobe beamforming with accurate and deep nulls towards each probing source. This work has application to the active radar cross secti...

  18. 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.

  19. Linear and nonlinear stability of periodic orbits in annular billiards

    Science.gov (United States)

    Dettmann, Carl P.; Fain, Vitaly

    2017-04-01

    An annular billiard is a dynamical system in which a particle moves freely in a disk except for elastic collisions with the boundary and also a circular scatterer in the interior of the disk. We investigate the stability properties of some periodic orbits in annular billiards in which the scatterer is touching or close to the boundary. We analytically show that there exist linearly stable periodic orbits of an arbitrary period for scatterers with decreasing radii that are located near the boundary of the disk. As the position of the scatterer moves away from a symmetry line of a periodic orbit, the stability of periodic orbits changes from elliptic to hyperbolic, corresponding to a saddle-center bifurcation. When the scatterer is tangent to the boundary, the periodic orbit is parabolic. We prove that slightly changing the reflection angle of the orbit in the tangential situation leads to the existence of Kolmogorov-Arnold-Moser islands. Thus, we show that there exists a decreasing to zero sequence of open intervals of scatterer radii, along which the billiard table is not ergodic.

  20. Asymptotics of linear initial boundary value problems with periodic boundary data on the half-line and finite intervals

    KAUST Repository

    Dujardin, G. M.

    2009-08-12

    This paper deals with the asymptotic behaviour of the solutions of linear initial boundary value problems with constant coefficients on the half-line and on finite intervals. We assume that the boundary data are periodic in time and we investigate whether the solution becomes time-periodic after sufficiently long time. Using Fokas\\' transformation method, we show that, for the linear Schrödinger equation, the linear heat equation and the linearized KdV equation on the half-line, the solutions indeed become periodic for large time. However, for the same linear Schrödinger equation on a finite interval, we show that the solution, in general, is not asymptotically periodic; actually, the asymptotic behaviour of the solution depends on the commensurability of the time period T of the boundary data with the square of the length of the interval over. © 2009 The Royal Society.

  1. 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.

  2. 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.

  3. Detection of very long period solar free oscillations in ambient seismic array noise

    Science.gov (United States)

    Caton, R.; Pavlis, G. L.; Thomson, D. J.; Vernon, F.

    2017-12-01

    For nearly two decades long-period seismologists have been aware that the Earth's free oscillations are in a constant state of excitement, even in the absence of large earthquakes. This phenomenon is now called the "Earth's hum," and much research has been done to determine what generates this hum. Here we examine a hypothesis first put forward by Thomson et al. in 2007 that a portion of the hum's energy comes from the sun. They hypothesized that solar free oscillations couple into the solid Earth, likely through electromagnetic processes, and produce signals that are observable in the frequency domain. If this is true, then at least some measurement of helioseismic oscillations may be possible using relatively cheap, ground-based instruments rather than spacecraft. In this project we attempt to improve upon previous studies by producing spectra from seismic arrays, rather than a single station. We use data from two arrays: The Homestake Mine 3D array in Lead, SD, and the Pinyon Flats array, which has seismometers in boreholes drilled into bedrock. Both have exceptionally low noise levels at ultra long periods and show easily visible earth tides on horizontal component data filtered to below the microseism band. In the Homestake data, below 500 μHz we have found evidence of what we suggest may be closely spaced solar g-mode lines. Such modes are produced by a density inversion at the top of the solar core. There is no sign of these modes in the Pinyon Flats data, but we find this is likely due to the signal-to-noise ratio of those data, which is significantly lower than Homestake. Significance tests of bands below 500 μHz indicate with probability levels as high as 40σ that these lines are not the result of random processes. Critical examination of our processing steps for sources of bias indicate that the observed line structure is not a processing artifact.

  4. EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Palaversa, Lovro; Eyer, Laurent; Rimoldini, Lorenzo [Observatoire Astronomique de l' Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Ivezić, Željko; Loebman, Sarah; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Becker, Andrew C. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States); Ruždjak, Domagoj; Sudar, Davor; Božić, Hrvoje [Hvar Observatory, Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Galin, Mario [Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana [Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Srdoč, Gregor, E-mail: lovro.palaversa@unige.ch [Saršoni 90, 51216 Viškovo (Croatia); and others

    2013-10-01

    We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg{sup 2} of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the

  5. 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

  6. Ambient noise adjoint tomography for a linear array in North China

    Science.gov (United States)

    Zhang, C.; Yao, H.; Liu, Q.; Yuan, Y. O.; Zhang, P.; Feng, J.; Fang, L.

    2017-12-01

    Ambient noise tomography based on dispersion data and ray theory has been widely utilized for imaging crustal structures. In order to improve the inversion accuracy, ambient noise tomography based on the 3D adjoint approach or full waveform inversion has been developed recently, however, the computational cost is tremendous. In this study we present 2D ambient noise adjoint tomography for a linear array in north China with significant computational efficiency compared to 3D ambient noise adjoint tomography. During the preprocessing, we first convert the observed data in 3D media, i.e., surface-wave empirical Green's functions (EGFs) from ambient noise cross-correlation, to the reconstructed EGFs in 2D media using a 3D/2D transformation scheme. Different from the conventional steps of measuring phase dispersion, the 2D adjoint tomography refines 2D shear wave speeds along the profile directly from the reconstructed Rayleigh wave EGFs in the period band 6-35s. With the 2D initial model extracted from the 3D model from traditional ambient noise tomography, adjoint tomography updates the model by minimizing the frequency-dependent Rayleigh wave traveltime misfits between the reconstructed EGFs and synthetic Green function (SGFs) in 2D media generated by the spectral-element method (SEM), with a preconditioned conjugate gradient method. The multitaper traveltime difference measurement is applied in four period bands during the inversion: 20-35s, 15-30s, 10-20s and 6-15s. The recovered model shows more detailed crustal structures with pronounced low velocity anomaly in the mid-lower crust beneath the junction of Taihang Mountains and Yin-Yan Mountains compared with the initial model. This low velocity structure may imply the possible intense crust-mantle interactions, probably associated with the magmatic underplating during the Mesozoic to Cenozoic evolution of the region. To our knowledge, it's first time that ambient noise adjoint tomography is implemented in 2D media

  7. Temperature and pinning strength dependence of the critical current of a superconductor with a square periodic array of pinning sites

    International Nuclear Information System (INIS)

    Benkraouda, M.; Obaidat, I.M.; Al Khawaja, U.

    2006-01-01

    We have conducted extensive series of molecular dynamic simulations on driven vortex lattices interacting with periodic square arrays of pinning sites. In solving the over damped equation of vortex motion we took into account the vortex-vortex repulsion interaction, the attractive vortex-pinning interaction, and the driving Lorentz force at several values of temperature. We have studied the effect of varying the driving Lorentz force and varying the pinning strength on the critical current for several pinning densities, and temperature values. We have found that the pinning strength play an important role in enhancing the critical current over the whole temperature range. At low temperatures, the critical current was found to increase linearly with increasing the pinning strengths for all pinning densities. As the temperature increases, the effect of small pinning strengths diminishes and becomes insignificant at high temperatures

  8. 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

  9. 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.

  10. A Lie-Deprit perturbation algorithm for linear differential equations with periodic coefficients

    OpenAIRE

    Casas Pérez, Fernando; Chiralt Monleon, Cristina

    2014-01-01

    A perturbative procedure based on the Lie-Deprit algorithm of classical mechanics is proposed to compute analytic approximations to the fundamental matrix of linear di erential equations with periodic coe cients. These approximations reproduce the structure assured by the Floquet theorem. Alternatively, the algorithm provides explicit approximations to the Lyapunov transformation reducing the original periodic problem to an autonomous sys- tem and also to its characteristic ...

  11. 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.

  12. Periodic inventory system in cafeteria using linear programming

    Science.gov (United States)

    Usop, Mohd Fais; Ishak, Ruzana; Hamdan, Ahmad Ridhuan

    2017-11-01

    Inventory management is an important factor in running a business. It plays a big role of managing the stock in cafeteria. If the inventories are failed to be managed wisely, it will affect the profit of the cafeteria. Therefore, the purpose of this study is to find the solution of the inventory management in cafeteria. Most of the cafeteria in Malaysia did not manage their stock well. Therefore, this study is to propose a database system of inventory management and to develop the inventory model in cafeteria management. In this study, new database system to improve the management of the stock in a weekly basis will be provided using Linear Programming Model to get the optimal range of the inventory needed for selected categories. Data that were collected by using the Periodic Inventory System at the end of the week within three months period being analyzed by using the Food Stock-take Database. The inventory model was developed from the collected data according to the category of the inventory in the cafeteria. Results showed the effectiveness of using the Periodic Inventory System and will be very helpful to the cafeteria management in organizing the inventory. Moreover, the findings in this study can reduce the cost of operation and increased the profit.

  13. Linear and Non-Linear Dielectric Response of Periodic Systems from Quantum Monte Carlo

    Science.gov (United States)

    Umari, Paolo

    2006-03-01

    We present a novel approach that allows to calculate the dielectric response of periodic systems in the quantum Monte Carlo formalism. We employ a many-body generalization for the electric enthalpy functional, where the coupling with the field is expressed via the Berry-phase formulation for the macroscopic polarization. A self-consistent local Hamiltonian then determines the ground-state wavefunction, allowing for accurate diffusion quantum Monte Carlo calculations where the polarization's fixed point is estimated from the average on an iterative sequence. The polarization is sampled through forward-walking. This approach has been validated for the case of the polarizability of an isolated hydrogen atom, and then applied to a periodic system. We then calculate the linear susceptibility and second-order hyper-susceptibility of molecular-hydrogen chains whith different bond-length alternations, and assess the quality of nodal surfaces derived from density-functional theory or from Hartree-Fock. The results found are in excellent agreement with the best estimates obtained from the extrapolation of quantum-chemistry calculations.P. Umari, A.J. Williamson, G. Galli, and N. MarzariPhys. Rev. Lett. 95, 207602 (2005).

  14. 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)

  15. 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.

  16. 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.

  17. 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)

  18. Improved harmonic balance approach to periodic solutions of non-linear jerk equations

    International Nuclear Information System (INIS)

    Wu, B.S.; Lim, C.W.; Sun, W.P.

    2006-01-01

    An analytical approximate approach for determining periodic solutions of non-linear jerk equations involving third-order time-derivative is presented. This approach incorporates salient features of both Newton's method and the method of harmonic balance. By appropriately imposing the method of harmonic balance to the linearized equation, the approach requires only one or two iterations to predict very accurate analytical approximate solutions for a large range of initial velocity amplitude. One typical example is used to verify and illustrate the usefulness and effectiveness of the proposed approach

  19. Preparations, Properties, and Applications of Periodic Nano Arrays using Anodized Aluminum Oxide and Di-block Copolymer

    Science.gov (United States)

    Noh, Kunbae

    2011-12-01

    Self-ordered arrangements observed in various materials systems such as anodic aluminum oxide, polystyrene nanoparticles, and block copolymer are of great interest in terms of providing new opportunities in nanofabrication field where lithographic techniques are broadly used in general. Investigations on self-assembled nano arrays to understand how to obtain periodic nano arrays in an efficient yet inexpensive way, and how to realize advanced material and device systems thereof, can lead to significant impacts on science and technology for many forefront device applications. In this thesis, various aspects of periodic nano-arrays have been discussed including novel preparations, properties and applications of anodized aluminum oxide (AAO) and PS-b-P4VP (S4VP) di-block copolymer self-assembly. First, long-range ordered AAO arrays have been demonstrated. Nanoimprint lithography (NIL) process allowed a faithful pattern transfer of the imprint mold pattern onto Al thin film, and interesting self-healing and pattern tripling phenomena were observed, which could be applicable towards fabrication of the NIL master mold having highly dense pattern over large area, useful for fabrication of a large-area substrate for predictable positioning of arrayed devices. Second, S4VP diblock copolymer self-assembly and S4VP directed AAO self-assembly have been demonstrated in the Al thin film on Si substrate. Such a novel combination of two dissimilar self-assembly techniques demonstrated a potential as a versatile tool for nanopatterning formation on a Si substrate, capable of being integrated into Si process technology. As exemplary applications, vertically aligned Ni nanowires have been synthesized into an S4VP-guided AAO membrane on a Si substrate in addition to anti-dot structured [Co/Pd]n magnetic multilayer using S4VP self assembly. Third, a highly hexagonally ordered, vertically parallel aluminum oxide nanotube array was successfully fabricated via hard anodization technique

  20. Linear theory period ratios for surface helium enhanced double-mode Cepheids

    International Nuclear Information System (INIS)

    Cox, A.N.; Hodson, S.W.; King, D.S.

    1979-01-01

    Linear nonadiabatic theory period ratios for models of double-mode Cepheids with their two periods between 1 and 7 days have been computed, assuming differing amounts and depths of surface helium enhancement. Evolution theory masses and luminosities are found to be consistent with the observed periods. All models give Pi 1 /Pi 0 approx. =0.70 as observed for the 11 known variables, contrary to previous theoretical conclusions. The composition structure that best fits the period ratios has the helium mass fraction in the outer 10 -3 of the stellar mass (T< or =250,000 K) as 0.65, similar to a previous model for the triple-mode pulsator AC And. This enrichment can be established by a Cepheid wind and downward inverted μ gradient instability mixing in the lifetime of these low-mass classical Cepheids

  1. Seismometer array station processors

    International Nuclear Information System (INIS)

    Key, F.A.; Lea, T.G.; Douglas, A.

    1977-01-01

    A description is given of the design, construction and initial testing of two types of Seismometer Array Station Processor (SASP), one to work with data stored on magnetic tape in analogue form, the other with data in digital form. The purpose of a SASP is to detect the short period P waves recorded by a UK-type array of 20 seismometers and to edit these on to a a digital library tape or disc. The edited data are then processed to obtain a rough location for the source and to produce seismograms (after optimum processing) for analysis by a seismologist. SASPs are an important component in the scheme for monitoring underground explosions advocated by the UK in the Conference of the Committee on Disarmament. With digital input a SASP can operate at 30 times real time using a linear detection process and at 20 times real time using the log detector of Weichert. Although the log detector is slower, it has the advantage over the linear detector that signals with lower signal-to-noise ratio can be detected and spurious large amplitudes are less likely to produce a detection. It is recommended, therefore, that where possible array data should be recorded in digital form for input to a SASP and that the log detector of Weichert be used. Trial runs show that a SASP is capable of detecting signals down to signal-to-noise ratios of about two with very few false detections, and at mid-continental array sites it should be capable of detecting most, if not all, the signals with magnitude above msub(b) 4.5; the UK argues that, given a suitable network, it is realistic to hope that sources of this magnitude and above can be detected and identified by seismological means alone. (author)

  2. Fast computation of the Maslov index for hyperbolic linear systems with periodic coefficients

    International Nuclear Information System (INIS)

    Chardard, F; Dias, F; Bridges, T J

    2006-01-01

    The Maslov index is a topological property of periodic orbits of finite-dimensional Hamiltonian systems that is widely used in semiclassical quantization, quantum chaology, stability of waves and classical mechanics. The Maslov index is determined from the analysis of a linear Hamiltonian system with periodic coefficients. In this paper, a numerical scheme is devised to compute the Maslov index for hyperbolic linear systems when the phase space has a low dimension. The idea is to compute on the exterior algebra of the ambient vector space, where the Lagrangian subspace representing the unstable subspace is reduced to a line. When the exterior algebra is projectified the Lagrangian subspace always forms a closed loop. The idea is illustrated by application to Hamiltonian systems on a phase space of dimension 4. The theory is used to compute the Maslov index for the spectral problem associated with periodic solutions of the fifth-order Korteweg de Vries equation

  3. Using a 2D detector array for meaningful and efficient linear accelerator beam property validations.

    Science.gov (United States)

    Ritter, Timothy A; Gallagher, Ian; Roberson, Peter L

    2014-11-08

    Following linear accelerator commissioning, the qualified medical physicist is responsible for monitoring the machine's ongoing performance, detecting and investigating any changes in beam properties, and assessing the impact of unscheduled repairs. In support of these responsibilities, the authors developed a method of using a 2D ionization chamber array to efficiently test and validate important linear accelerator photon beam properties. A team of three physicists identified critical properties of the accelerator and developed constancy tests that were sensitive to each of the properties. The result was a 14-field test plan. The test plan includes large and small fields at varying depths, a reduced SSD field at shallow depth for sensitivity to extra focal photon and electron components, and analysis of flatness, symmetry, dose, dose profiles, and dose ratios. Constancy tests were repeated five times over a period of six weeks and used to set upper and lower investigation levels at ± 3 SDs. Deliberate variations in output, penumbra, and energy were tested to determine the suitability of the proposed method. Measurements were also performed on a similar, but distinct, machine to assess test sensitivity. The results demonstrated upper and lower investigation levels significantly smaller than the comparable TG-142 annual recommendations, with the exception of the surrogate used for output calibration, which still fell within the TG-142 monthly recommendation. Subtle changes in output, beam energy, and penumbra were swiftly identified for further investigation. The test set identified the distinct nature of the second accelerator. The beam properties of two photon energies can be validated in approximately 1.5 hrs using this method. The test suite can be used to evaluate the impact of minor repairs, detect changes in machine performance over time, and supplement other machine quality assurance testing.

  4. 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).

  5. 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.

  6. Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, J [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Franco, L [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Gomez, F [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Iglesias, A [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Pazos, A [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Pena, J [Departamento de Fisica de Particulas, Facultade de Fisica, 15782 Santiago de Compostela (Spain); Lobato, R [Hospital Clinico Universitario de Santiago, Santiago (Spain); Mosquera, J [Hospital Clinico Universitario de Santiago, Santiago (Spain); Pombar, M [Hospital Clinico Universitario de Santiago, Santiago (Spain); Sendon, J [Hospital Clinico Universitario de Santiago, Santiago (Spain)

    2005-04-21

    A liquid isooctane (C{sub 8}H{sub 18}) 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 1.7 mm x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min{sup -1}, and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm{sup 3} air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio.

  7. Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

    International Nuclear Information System (INIS)

    Pardo, J; Franco, L; Gomez, F; Iglesias, A; Pazos, A; Pena, J; Lobato, R; Mosquera, J; Pombar, M; Sendon, J

    2005-01-01

    A liquid isooctane (C 8 H 18 ) 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 1.7 mm x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min -1 , and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm 3 air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio

  8. Direction-of-Arrival Estimation for Coprime Array Using Compressive Sensing Based Array Interpolation

    Directory of Open Access Journals (Sweden)

    Aihua Liu

    2017-01-01

    Full Text Available A method of direction-of-arrival (DOA estimation using array interpolation is proposed in this paper to increase the number of resolvable sources and improve the DOA estimation performance for coprime array configuration with holes in its virtual array. The virtual symmetric nonuniform linear array (VSNLA of coprime array signal model is introduced, with the conventional MUSIC with spatial smoothing algorithm (SS-MUSIC applied on the continuous lags in the VSNLA; the degrees of freedom (DoFs for DOA estimation are obviously not fully exploited. To effectively utilize the extent of DoFs offered by the coarray configuration, a compressing sensing based array interpolation algorithm is proposed. The compressing sensing technique is used to obtain the coarse initial DOA estimation, and a modified iterative initial DOA estimation based interpolation algorithm (IMCA-AI is then utilized to obtain the final DOA estimation, which maps the sample covariance matrix of the VSNLA to the covariance matrix of a filled virtual symmetric uniform linear array (VSULA with the same aperture size. The proposed DOA estimation method can efficiently improve the DOA estimation performance. The numerical simulations are provided to demonstrate the effectiveness of the proposed method.

  9. A Mixed-Integer Linear Programming approach to wind farm layout and inter-array cable routing

    DEFF Research Database (Denmark)

    Fischetti, Martina; Leth, John-Josef; Borchersen, Anders Bech

    2015-01-01

    A Mixed-Integer Linear Programming (MILP) approach is proposed to optimize the turbine allocation and inter-array offshore cable routing. The two problems are considered with a two steps strategy, solving the layout problem first and then the cable problem. We give an introduction to both problems...... and present the MILP models we developed to solve them. To deal with interference in the onshore cases, we propose an adaptation of the standard Jensen’s model, suitable for 3D cases. A simple Stochastic Programming variant of our model allows us to consider different wind scenarios in the optimization...

  10. RF properties of periodic accelerating structures for linear colliders

    International Nuclear Information System (INIS)

    Wang, J.W.

    1989-07-01

    With the advent of the SLAC electron-positron linear collider (SLC) in the 100 GeV center-of-mass energy range, research and development work on even higher energy machines of this type has started in several laboratories in the United States, Europe, the Soviet Union and Japan. These linear colliders appear to provide the only promising approach to studying e + e - physics at center-of-mass energies approaching 1 TeV. This thesis concerns itself with the study of radio frequency properties of periodic accelerating structures for linear colliders and their interaction with bunched beams. The topics that have been investigated are: experimental measurements of the energy loss of single bunches to longitudinal modes in two types of structures, using an equivalent signal on a coaxial wire to simulate the beam; a method of canceling the energy spread created within a single bunch by longitudinal wakefields, through appropriate shaping of the longitudinal charge distribution of the bunch; derivation of the complete transient beam-loading equation for a train of bunches passing through a constant-gradient accelerator section, with application to the calculation and minimization of multi-bunch energy spread; detailed study of field emission and radio frequency breakdown in disk-loaded structures at S-, C- and X-band frequencies under extremely high-gradient conditions, with special attention to thermal effects, radiation, sparking, emission of gases, surface damage through explosive emission and its possible control through RF-gas processing. 53 refs., 49 figs., 9 tabs

  11. Linear array of photodiodes to track a human speaker for video recording

    International Nuclear Information System (INIS)

    DeTone, D; Neal, H; Lougheed, R

    2012-01-01

    Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant– the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting–a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

  12. Linear array of photodiodes to track a human speaker for video recording

    Science.gov (United States)

    DeTone, D.; Neal, H.; Lougheed, R.

    2012-12-01

    Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

  13. Array processors based on Gaussian fraction-free method

    Energy Technology Data Exchange (ETDEWEB)

    Peng, S; Sedukhin, S [Aizu Univ., Aizuwakamatsu, Fukushima (Japan); Sedukhin, I

    1998-03-01

    The design of algorithmic array processors for solving linear systems of equations using fraction-free Gaussian elimination method is presented. The design is based on a formal approach which constructs a family of planar array processors systematically. These array processors are synthesized and analyzed. It is shown that some array processors are optimal in the framework of linear allocation of computations and in terms of number of processing elements and computing time. (author)

  14. Plane-wave scattering from half-wave dipole arrays

    DEFF Research Database (Denmark)

    Jensen, Niels E.

    1970-01-01

    A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays.......A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays....

  15. Displacement measurement system for linear array detector

    International Nuclear Information System (INIS)

    Zhang Pengchong; Chen Ziyu; Shen Ji

    2011-01-01

    It presents a set of linear displacement measurement system based on encoder. The system includes displacement encoders, optical lens and read out circuit. Displacement read out unit includes linear CCD and its drive circuit, two amplifier circuits, second order Butterworth low-pass filter and the binarization circuit. The coding way is introduced, and various parts of the experimental signal waveforms are given, and finally a linear experimental test results are given. The experimental results are satisfactory. (authors)

  16. Performance study of monochromatic synchrotron X-ray computed tomography using a linear array detector

    Energy Technology Data Exchange (ETDEWEB)

    Kazama, Masahiro; Takeda, Tohoru; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Akiba, Masahiro; Yuasa, Tetsuya; Hyodo, Kazuyuki; Ando, Masami; Akatsuka, Takao

    1997-09-01

    Monochromatic x-ray computed tomography (CT) using synchrotron radiation (SR) is being developed for detection of non-radioactive contrast materials at low concentration for application in clinical diagnosis. A new SR-CT system with improved contrast resolution, was constructed using a linear array detector which provides wide dynamic ranges and a double monochromator. The performance of this system was evaluated in a phantom and a rat model of brain ischemia. This system consists of a silicon (111) double crystal monochromator, an x-ray shutter, an ionization chamber, x-ray slits, a scanning table for the target organ, and an x-ray linear array detector. The research was carried out at the BLNE-5A bending magnet beam line of the Tristan Accumulation Ring in KEK, Japan. In this experiment, the reconstructed image of the spatial-resolution phantom clearly showed the 1 mm holes. At 1 mm slice thickness, the above K-edge image of the phantom showed contrast resolution at the concentration of 200 {mu}g/ml iodine-based contrast materials whereas the K-edge energy subtraction image showed contrast resolution at the concentration of 500 {mu}g/ml contrast materials. The cerebral arteries filled with iodine microspheres were clearly revealed, and the ischemic regions at the right temporal lobe and frontal lobe were depicted as non-vascular regions. The measured minimal detectable concentration of iodine on the above K-edge image is about 6 times higher than the expected value of 35.3 {mu}g/ml because of the high dark current of this detector. Thus, the use of a CCD detector which is cooled by liquid nitrogen to improve the dynamic range of the detector, is being under construction. (author)

  17. Localized and periodic exact solutions to the nonlinear Schroedinger equation with spatially modulated parameters: Linear and nonlinear lattices

    International Nuclear Information System (INIS)

    Belmonte-Beitia, Juan; Konotop, Vladimir V.; Perez-Garcia, Victor M.; Vekslerchik, Vadym E.

    2009-01-01

    Using similarity transformations we construct explicit solutions of the nonlinear Schroedinger equation with linear and nonlinear periodic potentials. We present explicit forms of spatially localized and periodic solutions, and study their properties. We put our results in the framework of the exploited perturbation techniques and discuss their implications on the properties of associated linear periodic potentials and on the possibilities of stabilization of gap solitons using polychromatic lattices.

  18. Finding Traps in Non-linear Spin Arrays

    OpenAIRE

    Wiesniak, Marcin; Markiewicz, Marcin

    2009-01-01

    Precise knowledge of the Hamiltonian of a system is a key to many of its applications. Tasks such state transfer or quantum computation have been well studied with a linear chain, but hardly with systems, which do not possess a linear structure. While this difference does not disturb the end-to-end dynamics of a single excitation, the evolution is significantly changed in other subspaces. Here we quantify the difference between a linear chain and a pseudo-chain, which have more than one spin ...

  19. Design and optimization of multi-class series-parallel linear electromagnetic array artificial muscle.

    Science.gov (United States)

    Li, Jing; Ji, Zhenyu; Shi, Xuetao; You, Fusheng; Fu, Feng; Liu, Ruigang; Xia, Junying; Wang, Nan; Bai, Jing; Wang, Zhanxi; Qin, Xiansheng; Dong, Xiuzhen

    2014-01-01

    Skeletal muscle exhibiting complex and excellent precision has evolved for millions of years. Skeletal muscle has better performance and simpler structure compared with existing driving modes. Artificial muscle may be designed by analyzing and imitating properties and structure of skeletal muscle based on bionics, which has been focused on by bionic researchers, and a structure mode of linear electromagnetic array artificial muscle has been designed in this paper. Half sarcomere is the minimum unit of artificial muscle and electromagnetic model has been built. The structural parameters of artificial half sarcomere actuator were optimized to achieve better movement performance. Experimental results show that artificial half sarcomere actuator possesses great motion performance such as high response speed, great acceleration, small weight and size, robustness, etc., which presents a promising application prospect of artificial half sarcomere actuator.

  20. 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 %

  1. Conformal array design on arbitrary polygon surface with transformation optics

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Li, E-mail: dengl@bupt.edu.cn; Hong, Weijun, E-mail: hongwj@bupt.edu.cn; Zhu, Jianfeng; Peng, Biao; Li, Shufang [Beijing Key Laboratory of Network System Architecture and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, 100876 Beijing (China); Wu, Yongle, E-mail: wuyongle138@gmail.com [Beijing Key Laboratory of Work Safety Intelligent Monitoring, School of Electronic Engineering, Beijing University of Posts and Telecommunications, 100876 Beijing (China)

    2016-06-15

    A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

  2. Conformal array design on arbitrary polygon surface with transformation optics

    International Nuclear Information System (INIS)

    Deng, Li; Hong, Weijun; Zhu, Jianfeng; Peng, Biao; Li, Shufang; Wu, Yongle

    2016-01-01

    A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

  3. Accumulation of unstable periodic orbits and the stickiness in the two-dimensional piecewise linear map.

    Science.gov (United States)

    Akaishi, A; Shudo, A

    2009-12-01

    We investigate the stickiness of the two-dimensional piecewise linear map with a family of marginal unstable periodic orbits (FMUPOs), and show that a series of unstable periodic orbits accumulating to FMUPOs plays a significant role to give rise to the power law correlation of trajectories. We can explicitly specify the sticky zone in which unstable periodic orbits whose stability increases algebraically exist, and find that there exists a hierarchy in accumulating periodic orbits. In particular, the periodic orbits with linearly increasing stability play the role of fundamental cycles as in the hyperbolic systems, which allows us to apply the method of cycle expansion. We also study the recurrence time distribution, especially discussing the position and size of the recurrence region. Following the definition adopted in one-dimensional maps, we show that the recurrence time distribution has an exponential part in the short time regime and an asymptotic power law part. The analysis on the crossover time T(c)(*) between these two regimes implies T(c)(*) approximately -log[micro(R)] where micro(R) denotes the area of the recurrence region.

  4. Design of circular differential microphone arrays

    CERN Document Server

    Benesty, Jacob; Cohen, Israel

    2015-01-01

    Recently, we proposed a completely novel and efficient way to design differential beamforming algorithms for linear microphone arrays. Thanks to this very flexible approach, any order of differential arrays can be designed. Moreover, they can be made robust against white noise amplification, which is the main inconvenience in these types of arrays. The other well-known problem with linear arrays is that electronic steering is not really feasible.  In this book, we extend all these fundamental ideas to circular microphone arrays and show that we can design small and compact differential arrays of any order that can be electronically steered in many different directions and offer a good degree of control of the white noise amplification problem, high directional gain, and frequency-independent response. We also present a number of practical examples, demonstrating that differential beamforming with circular microphone arrays is likely one of the best candidates for applications involving speech enhancement (i....

  5. Bounded solutions of self-adjoint second order linear difference equations with periodic coeffients

    Directory of Open Access Journals (Sweden)

    Encinas A.M.

    2018-02-01

    Full Text Available In this work we obtain easy characterizations for the boundedness of the solutions of the discrete, self–adjoint, second order and linear unidimensional equations with periodic coefficients, including the analysis of the so-called discrete Mathieu equations as particular cases.

  6. 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.

  7. On the stability, the periodic solutions and the resolution of certain types of non linear equations, and of non linearly coupled systems of these equations, appearing in betatronic oscillations

    International Nuclear Information System (INIS)

    Valat, J.

    1960-12-01

    Universal stability diagrams have been calculated and experimentally checked for Hill-Meissner type equations with square-wave coefficients. The study of these equations in the phase-plane has then made it possible to extend the periodic solution calculations to the case of non-linear differential equations with periodic square-wave coefficients. This theory has been checked experimentally. For non-linear coupled systems with constant coefficients, a search was first made for solutions giving an algebraic motion. The elliptical and Fuchs's functions solve such motions. The study of non-algebraic motions is more delicate, apart from the study of nonlinear Lissajous's motions. A functional analysis shows that it is possible however in certain cases to decouple the system and to find general solutions. For non-linear coupled systems with periodic square-wave coefficients it is then possible to calculate the conditions leading to periodic solutions, if the two non-linear associated systems with constant coefficients fall into one of the categories of the above paragraph. (author) [fr

  8. Phase retrieval in near-field measurements by array synthesis

    DEFF Research Database (Denmark)

    Wu, Jian; Larsen, Flemming Holm

    1991-01-01

    The phase retrieval problem in near-field antenna measurements is formulated as an array synthesis problem. As a test case, a particular synthesis algorithm has been used to retrieve the phase of a linear array......The phase retrieval problem in near-field antenna measurements is formulated as an array synthesis problem. As a test case, a particular synthesis algorithm has been used to retrieve the phase of a linear array...

  9. 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)

  10. Performance of a high-resolution depth-encoding PET detector module using linearly-graded SiPM arrays

    Science.gov (United States)

    Du, Junwei; Bai, Xiaowei; Gola, Alberto; Acerbi, Fabio; Ferri, Alessandro; Piemonte, Claudio; Yang, Yongfeng; Cherry, Simon R.

    2018-02-01

    The goal of this study was to exploit the excellent spatial resolution characteristics of a position-sensitive silicon photomultiplier (SiPM) and develop a high-resolution depth-of-interaction (DOI) encoding positron emission tomography (PET) detector module. The detector consists of a 30  ×  30 array of 0.445  ×  0.445  ×  20 mm3 polished LYSO crystals coupled to two 15.5  ×  15.5 mm2 linearly-graded SiPM (LG-SiPM) arrays at both ends. The flood histograms show that all the crystals in the LYSO array can be resolved. The energy resolution, the coincidence timing resolution and the DOI resolution were 21.8  ±  5.8%, 1.23  ±  0.10 ns and 3.8  ±  1.2 mm, respectively, at a temperature of -10 °C and a bias voltage of 35.0 V. The performance did not degrade significantly for event rates of up to 130 000 counts s-1. This detector represents an attractive option for small-bore PET scanner designs that simultaneously emphasize high spatial resolution and high detection efficiency, important, for example, in preclinical imaging of the rodent brain with neuroreceptor ligands.

  11. A New Approach in the Simplification of a Multiple-Beam Forming Network Based on CORPS Using Compressive Arrays

    Directory of Open Access Journals (Sweden)

    Armando Arce

    2012-01-01

    Full Text Available This research paper deals with a innovative way to simplify the design of beam-forming networks (BFNs for multibeam steerable antenna arrays based on coherently radiating periodic structures (CORPS technology using the noniterative matrix pencil method (MPM. This design approach is based on the application of the MPM to linear arrays fed by CORPS-BFN configurations to further reduce the complexity of the beam-forming network. Two 2-beam design configurations of CORPS-BFN for a steerable linear array are analyzed and compared using this compressive method. Simulation results show the effectiveness and advantages of applying the MPM on BFNs based on CORPS exploiting the nonuniformity of the antenna elements. Furthermore, final results show that the integration of CORPS-BFN and MPM reduces the entire antenna system including the antenna array and the beam-forming network subsystem resulting in a substantial simplification in such systems.

  12. Electromagnetic Linear Vibration Energy Harvester Using Sliding Permanent Magnet Array and Ferrofluid as a Lubricant

    Directory of Open Access Journals (Sweden)

    Song Hee Chae

    2017-09-01

    Full Text Available We present an electromagnetic linear vibration energy harvester with an array of rectangular permanent magnets as a springless proof mass. Instead of supporting the magnet assembly with spring element, ferrofluid has been used as a lubricating material. When external vibration is applied laterally to the harvester, magnet assembly slides back and forth on the channel with reduced friction and wear due to ferrofluid, which significantly improves the long-term reliability of the device. Electric power is generated across an array of copper windings formed at the bottom of the aluminum housing. A proof-of-concept harvester has been fabricated and tested with a vibration exciter at various input frequencies and accelerations. For the device where 5 μL of ferrofluid was used for lubrication, maximum output power of 493 μW has been generated, which was 4.37% higher than that without ferrofluid. Long-term reliability improvement due to ferrofluid lubrication has also been verified. For the device with ferrofluid, 1.02% decrease of output power has been observed, in contrast to 59.73% decrease of output power without ferrofluid after 93,600 cycles.

  13. Large-area 2D periodic crystalline silicon nanodome arrays on nanoimprinted glass exhibiting photonic band structure effects

    International Nuclear Information System (INIS)

    Becker, C; Lockau, D; Sontheimer, T; Rech, B; Schubert-Bischoff, P; Rudigier-Voigt, E; Bockmeyer, M; Schmidt, F

    2012-01-01

    Two-dimensional silicon nanodome arrays are prepared on large areas up to 50 cm 2 exhibiting photonic band structure effects in the near-infrared and visible wavelength region by downscaling a recently developed fabrication method based on nanoimprint-patterned glass, high-rate electron-beam evaporation of silicon, self-organized solid phase crystallization and wet-chemical etching. The silicon nanodomes, arranged in square lattice geometry with 300 nm lattice constant, are optically characterized by angular resolved reflection measurements, allowing the partial determination of the photonic band structure. This experimentally determined band structure agrees well with the outcome of three-dimensional optical finite-element simulations. A 16% photonic bandgap is predicted for an optimized geometry of the silicon nanodome arrays. By variation of the duration of the selective etching step, the geometry as well as the optical properties of the periodic silicon nanodome arrays can be controlled systematically. (paper)

  14. Characterization and linear array LA48 Commissioner for measuring the position of the multi leaf collimator

    International Nuclear Information System (INIS)

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

    2011-01-01

    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)

  15. Time-dependent transport of a localized surface plasmon through a linear array of metal nanoparticles: Precursor and normal mode contributions

    Science.gov (United States)

    Compaijen, P. J.; Malyshev, V. A.; Knoester, J.

    2018-02-01

    We theoretically investigate the time-dependent transport of a localized surface plasmon excitation through a linear array of identical and equidistantly spaced metal nanoparticles. Two different signals propagating through the array are found: one traveling with the group velocity of the surface plasmon polaritons of the system and damped exponentially, and the other running with the speed of light and decaying in a power-law fashion, as x-1 and x-2 for the transversal and longitudinal polarizations, respectively. The latter resembles the Sommerfeld-Brillouin forerunner and has not been identified in previous studies. The contribution of this signal dominates the plasmon transport at large distances. In addition, even though this signal is spread in the propagation direction and has the lateral dimension larger than the wavelength, the field profile close to the chain axis does not change with distance, indicating that this part of the signal is confined to the array.

  16. Impact of quadratic non-linearity on the dynamics of periodic solutions of a wave equation

    International Nuclear Information System (INIS)

    Kolesov, Andrei Yu; Rozov, Nikolai Kh

    2002-01-01

    For the non-linear telegraph equation with homogeneous Dirichlet or Neumann conditions at the end-points of a finite interval the question of the existence and the stability of time-periodic solutions bifurcating from the zero equilibrium state is considered. The dynamics of these solutions under a change of the diffusion coefficient (that is, the coefficient of the second derivative with respect to the space variable) is investigated. For the Dirichlet boundary conditions it is shown that this dynamics substantially depends on the presence - or the absence - of quadratic terms in the non-linearity. More precisely, it is shown that a quadratic non-linearity results in the occurrence, under an unbounded decrease of diffusion, of an infinite sequence of bifurcations of each periodic solution. En route, the related issue of the limits of applicability of Yu.S. Kolesov's method of quasinormal forms to the construction of self-oscillations in singularly perturbed hyperbolic boundary value problems is studied

  17. Periodic molybdenum disc array for light trapping in amorphous silicon layer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiwei; Deng, Changkai [International Center of Quantum and Molecular Structures, Materials Genome Institute, and Department of Physics, Shanghai University, 99 Shangda Road, Shanghai, 200444 China (China); Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China (China); Yang, Kang; Chen, Haiyan, E-mail: chenhy@sari.ac.cn; Li, Dongdong; Chen, Xiaoyuan [Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China (China); Ren, Wei, E-mail: renwei@shu.edu.cn [International Center of Quantum and Molecular Structures, Materials Genome Institute, and Department of Physics, Shanghai University, 99 Shangda Road, Shanghai, 200444 China (China)

    2016-05-15

    We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO{sub 2}. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under light illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.

  18. Parallel Access of Out-Of-Core Dense Extendible Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Otoo, Ekow J; Rotem, Doron

    2007-07-26

    Datasets used in scientific and engineering applications are often modeled as dense multi-dimensional arrays. For very large datasets, the corresponding array models are typically stored out-of-core as array files. The array elements are mapped onto linear consecutive locations that correspond to the linear ordering of the multi-dimensional indices. Two conventional mappings used are the row-major order and the column-major order of multi-dimensional arrays. Such conventional mappings of dense array files highly limit the performance of applications and the extendibility of the dataset. Firstly, an array file that is organized in say row-major order causes applications that subsequently access the data in column-major order, to have abysmal performance. Secondly, any subsequent expansion of the array file is limited to only one dimension. Expansions of such out-of-core conventional arrays along arbitrary dimensions, require storage reorganization that can be very expensive. Wepresent a solution for storing out-of-core dense extendible arrays that resolve the two limitations. The method uses a mapping function F*(), together with information maintained in axial vectors, to compute the linear address of an extendible array element when passed its k-dimensional index. We also give the inverse function, F-1*() for deriving the k-dimensional index when given the linear address. We show how the mapping function, in combination with MPI-IO and a parallel file system, allows for the growth of the extendible array without reorganization and no significant performance degradation of applications accessing elements in any desired order. We give methods for reading and writing sub-arrays into and out of parallel applications that run on a cluster of workstations. The axial-vectors are replicated and maintained in each node that accesses sub-array elements.

  19. Array measurements of long-period microtremors in southwestern Kanto plain, Japan; Kanto heiya nanseibu ni okeru yaya choshuki bido no array kansoku

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, H; Sato, H; Kurita, K; Seo, K [Tokyo Institute of Technology, Tokyo (Japan)

    1997-05-27

    Array measurements of long-period microtremors were carried out in the southwestern part of Kanto Plain, Japan, to obtain S-wave velocity structures in sedimentary beds as fundamental data for estimating long-term strong ground motion in Kanto Plain. The major component in a long-term seismic motion observed in Kanto Plain is the surface wave. According to the result of observations on Love wave by Kinoshita et al, the wavelengths of the surface waves of a long-term cycle are 10 to 20 km. Therefore, if an array observation is to be performed at intervals of about two wavelengths, about 40 points will be required to cover the entire Kanto plain. The final phase velocity is decided by averaging phase velocities of each cycle obtained for each data set. The acquired phase velocities are analyzed inversely by using a genetic algorithm to derive the S-wave velocities at each observation point. The present microtremor array observation has used 13 points in the southwestern part of Kanto Plain to acquire S-wave velocity (Vs) distribution in sedimentary beds. It was made clear that beds with Vs of 1.0 km/s and Vs of 1.5 km/s exist in this area between the surface bed and the seismic foundation with Vs of about 3 km/s. 10 refs., 10 figs., 1 tab.

  20. Coulomb gap triptych in a periodic array of metal nanocrystals.

    Science.gov (United States)

    Chen, Tianran; Skinner, Brian; Shklovskii, B I

    2012-09-21

    The Coulomb gap in the single-particle density of states (DOS) is a universal consequence of electron-electron interaction in disordered systems with localized electron states. Here we show that in arrays of monodisperse metallic nanocrystals, there is not one but three identical adjacent Coulomb gaps, which together form a structure that we call a "Coulomb gap triptych." We calculate the DOS and the conductivity in two- and three-dimensional arrays using a computer simulation. Unlike in the conventional Coulomb glass models, in nanocrystal arrays the DOS has a fixed width in the limit of large disorder. The Coulomb gap triptych can be studied via tunneling experiments.

  1. Acoustic emission linear pulse holography

    Science.gov (United States)

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

    1983-10-25

    This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

  2. Non-linear vibrational modes in biomolecules: A periodic orbits description

    International Nuclear Information System (INIS)

    Kampanarakis, Alexandros; Farantos, Stavros C.; Daskalakis, Vangelis; Varotsis, Constantinos

    2012-01-01

    Graphical abstract: Vibrational frequency shifts in Fe IV = O species of the active site of cytochrome c oxidase are attributed to changes in the surrounding Coulomb field. Periodic orbits analysis assists to find the most anharmonic modes in model biomolecules. Highlights: ► Periodic orbits are extended to multidimensional potentials of biomolecules. ► Highly anharmonic vibrational modes and center-saddle bifurcations are detected. ► Vibrational frequencies shifts in Oxoferryl species of CcO are observed. - Abstract: The vibrational harmonic normal modes of a molecule, which are valid at energies close to an equilibrium point (a minimum, maximum or saddle of the potential energy surface), are extended by periodic orbits to high energies where anharmonicity and coupling of the degrees of freedom are significant. In this way the assignment of the spectra, and thus the extraction of dynamics in highly excited molecules, can be obtained. New vibrational modes emanating from bifurcations of periodic orbits and long living localized trajectories signal the birth and localization of new quantum states. In this article we review and further study non-linear vibrational modes for model biomolecules such as alanine dipeptide and the active site in the oxoferryl oxidation state of the enzyme cytochrome c oxidase. We locate periodic orbits which exhibit high anhamonicity and lead to center-saddle bifurcations. These modes are associated to an isomerization process in alanine dipeptide and to frequency shifts in the oxoferryl observed by modifying the Coulomb field around the Imidazole–Fe IV = O species.

  3. Enhanced 2D-DOA Estimation for Large Spacing Three-Parallel Uniform Linear Arrays

    Directory of Open Access Journals (Sweden)

    Dong Zhang

    2018-01-01

    Full Text Available An enhanced two-dimensional direction of arrival (2D-DOA estimation algorithm for large spacing three-parallel uniform linear arrays (ULAs is proposed in this paper. Firstly, we use the propagator method (PM to get the highly accurate but ambiguous estimation of directional cosine. Then, we use the relationship between the directional cosine to eliminate the ambiguity. This algorithm not only can make use of the elements of the three-parallel ULAs but also can utilize the connection between directional cosine to improve the estimation accuracy. Besides, it has satisfied estimation performance when the elevation angle is between 70° and 90° and it can automatically pair the estimated azimuth and elevation angles. Furthermore, it has low complexity without using any eigen value decomposition (EVD or singular value decompostion (SVD to the covariance matrix. Simulation results demonstrate the effectiveness of our proposed algorithm.

  4. Remark on periodic boundary-value problem for second-order linear ordinary differential equations

    Czech Academy of Sciences Publication Activity Database

    Dosoudilová, M.; Lomtatidze, Alexander

    2018-01-01

    Roč. 2018, č. 13 (2018), s. 1-7 ISSN 1072-6691 Institutional support: RVO:67985840 Keywords : second-order linear equation * periodic boundary value problem * unique solvability Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 0.954, year: 2016 https://ejde.math.txstate.edu/Volumes/2018/13/abstr.html

  5. Observation of Nonlinear Self-Trapping of Broad Beams in Defocusing Waveguide Arrays

    International Nuclear Information System (INIS)

    Bennet, Francis H.; Haslinger, Franz; Neshev, Dragomir N.; Kivshar, Yuri S.; Alexander, Tristram J.; Mitchell, Arnan

    2011-01-01

    We demonstrate experimentally the localization of broad optical beams in periodic arrays of optical waveguides with defocusing nonlinearity. This observation in optics is linked to nonlinear self-trapping of Bose-Einstein-condensed atoms in stationary periodic potentials being associated with the generation of truncated nonlinear Bloch states, existing in the gaps of the linear transmission spectrum. We reveal that unlike gap solitons, these novel localized states can have an arbitrary width defined solely by the size of the input beam while independent of nonlinearity.

  6. Plasmon-negative refraction at the heterointerface of graphene sheet arrays.

    Science.gov (United States)

    Huang, He; Wang, Bing; Long, Hua; Wang, Kai; Lu, Peixiang

    2014-10-15

    We demonstrate negative refraction of surface plasmon polaritons (SPPs) at the heterointerface of two monolayer graphene sheet arrays (MGSAs) with different periods. The refraction angle is specifically related to the period ratio of the two MGSAs. By varying the incident Bloch momentum, the SPPs might be refracted in the direction normal to the heterointerface. Moreover, both positive and negative refraction could appear simultaneously. Because of the linear diffraction relation, the incident and refracted SPP beams experience diffraction-free propagation. The heterostructures composed of the MGSAs may find great applications in deep-subwavelength spatial light modulators, optical splitters, and switches.

  7. Periodic oscillations in linear continuous media coupled with nonlinear discrete systems

    International Nuclear Information System (INIS)

    Lupini, R.

    1998-01-01

    A general derivation of partial differential equations with boundary conditions in the form of ordinary differential equations is obtained using the principle of stationary action for a Lagrangian function composed of continuous plus discrete parts in interaction across the boundaries of a 1-dimensional medium. This approach leads directly to the theorem of energy conservation. For linear continuous medium, homogeneous Dirichlet condition at one boundary, and nonlinear oscillator at the other boundary, the entire differential problem reduces to a nonlinear differential-difference equation of neutral type and of the second order. The lag parameter is τ = l/c, where c is the phase speed, l the length of the continuum. The Author investigate the problem of the occurrence of periodic solutions of period integer multiple of the lag (super harmonic solutions) in the case of zero inertia of the boundary system. The problem for such oscillations is shown to reduce to systems of ordinary differential equations with matching conditions in a phase space of lower dimensionality: Phase-plane techniques are used to determine solutions of period 4τ, 8τ and 6τ

  8. Development of solenoid-induced helical wiggler with four poles per period

    International Nuclear Information System (INIS)

    Ohigashi, N.; Tsunawaki, Y.; Kiyochi, M.; Nakao, N.; Fujita, M.; Imasaki, K.; Nakai, S.; Mima, K.

    1999-01-01

    A new type of helical wiggler consisting of two staggered-iron arrays inserted into a solenoid field has been developed. The field measured by a test wiggler showed linear increment with the period. It was seen that 24% of the solenoid field contributed to the induced wiggler field when the gap length and the period of the wiggler were 16 and 24 mm, respectively. This wiggler would be useful for an FEL with a low-energy electron beam propagating in a strong axial guiding field

  9. Development of solenoid-induced helical wiggler with four poles per period

    CERN Document Server

    Ohigashi, N; Kiyochi, M; Nakao, N; Fujita, M; Imasaki, K; Nakai, S; Mima, K

    1999-01-01

    A new type of helical wiggler consisting of two staggered-iron arrays inserted into a solenoid field has been developed. The field measured by a test wiggler showed linear increment with the period. It was seen that 24% of the solenoid field contributed to the induced wiggler field when the gap length and the period of the wiggler were 16 and 24 mm, respectively. This wiggler would be useful for an FEL with a low-energy electron beam propagating in a strong axial guiding field.

  10. Application of Hybrid Optimization Algorithm in the Synthesis of Linear Antenna Array

    Directory of Open Access Journals (Sweden)

    Ezgi Deniz Ülker

    2014-01-01

    Full Text Available The use of hybrid algorithms for solving real-world optimization problems has become popular since their solution quality can be made better than the algorithms that form them by combining their desirable features. The newly proposed hybrid method which is called Hybrid Differential, Particle, and Harmony (HDPH algorithm is different from the other hybrid forms since it uses all features of merged algorithms in order to perform efficiently for a wide variety of problems. In the proposed algorithm the control parameters are randomized which makes its implementation easy and provides a fast response. This paper describes the application of HDPH algorithm to linear antenna array synthesis. The results obtained with the HDPH algorithm are compared with three merged optimization techniques that are used in HDPH. The comparison shows that the performance of the proposed algorithm is comparatively better in both solution quality and robustness. The proposed hybrid algorithm HDPH can be an efficient candidate for real-time optimization problems since it yields reliable performance at all times when it gets executed.

  11. Localization of periodic orbits of polynomial vector fields of even degree by linear functions

    Energy Technology Data Exchange (ETDEWEB)

    Starkov, Konstantin E. [CITEDI-IPN, Av. del Parque 1310, Mesa de Otay, Tijuana, BC (Mexico)] e-mail: konst@citedi.mx

    2005-08-01

    This paper is concerned with the localization problem of periodic orbits of polynomial vector fields of even degree by using linear functions. Conditions of the localization of all periodic orbits in sets of a simple structure are obtained. Our results are based on the solution of the conditional extremum problem and the application of homogeneous polynomial forms of even degrees. As examples, the Lanford system, the jerky system with one quadratic monomial and a quartically perturbed harmonic oscillator are considered.

  12. Localization of periodic orbits of polynomial vector fields of even degree by linear functions

    International Nuclear Information System (INIS)

    Starkov, Konstantin E.

    2005-01-01

    This paper is concerned with the localization problem of periodic orbits of polynomial vector fields of even degree by using linear functions. Conditions of the localization of all periodic orbits in sets of a simple structure are obtained. Our results are based on the solution of the conditional extremum problem and the application of homogeneous polynomial forms of even degrees. As examples, the Lanford system, the jerky system with one quadratic monomial and a quartically perturbed harmonic oscillator are considered

  13. Dynamics of Josephson junction arrays

    International Nuclear Information System (INIS)

    Hadley, P.

    1989-01-01

    The dynamics of Josephson junction arrays is a topic that lies at the intersection of the fields of nonlinear dynamics and Josephson junction technology. The series arrays considered here consist of several rapidly oscillating Josephson junctions where each junction is coupled equally to every other junction. The purpose of this study is to understand phaselocking and other cooperative dynamics of this system. Previously, little was known about high dimensional nonlinear systems of this sort. Numerical simulations are used to study the dynamics of these arrays. Three distinct types of periodic solutions to the array equations were observed as well as period doubled and chaotic solutions. One of the periodic solutions is the symmetric, in-phase solution where all of the junctions oscillate identically. The other two periodic solutions are symmetry-broken solutions where all of the junction do not oscillate identically. The symmetry-broken solutions are highly degenerate. As many as (N - 1) stable solutions can coexist for an array of N junctions. Understanding the stability of these several solutions and the transitions among them is vital to the design of useful devices

  14. Effects of combined linear and nonlinear periodic training on physical fitness and competition times in finswimmers.

    Science.gov (United States)

    Yu, Kyung-Hun; Suk, Min-Hwa; Kang, Shin-Woo; Shin, Yun-A

    2014-10-01

    The purpose of this study was to investigate the effect of combined linear and nonlinear periodic training on physical fitness and competition times in finswimmers. The linear resistance training model (6 days/week) and nonlinear underwater training (4 days/week) were applied to 12 finswimmers (age, 16.08± 1.44 yr; career, 3.78± 1.90 yr) for 12 weeks. Body composition measures included weight, body mass index (BMI), percent fat, and fat-free mass. Physical fitness measures included trunk flexion forward, trunk extension backward, sargent jump, 1-repetition-maximum (1 RM) squat, 1 RM dead lift, knee extension, knee flexion, trunk extension, trunk flexion, and competition times. Body composition and physical fitness were improved after the 12-week periodic training program. Weight, BMI, and percent fat were significantly decreased, and trunk flexion forward, trunk extension backward, sargent jump, 1 RM squat, 1 RM dead lift, and knee extension (right) were significantly increased. The 50- and 100-m times significantly decreased in all 12 athletes. After 12 weeks of training, all finswimmers who participated in this study improved their times in a public competition. These data indicate that combined linear and nonlinear periodic training enhanced the physical fitness and competition times in finswimmers.

  15. 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

  16. Exploration of deep S-wave velocity structure using microtremor array technique to estimate long-period ground motion

    International Nuclear Information System (INIS)

    Sato, Hiroaki; Higashi, Sadanori; Sato, Kiyotaka

    2007-01-01

    In this study, microtremor array measurements were conducted at 9 sites in the Niigata plain to explore deep S-wave velocity structures for estimation of long-period earthquake ground motion. The 1D S-wave velocity profiles in the Niigata plain are characterized by 5 layers with S-wave velocities of 0.4, 0.8, 1.5, 2.1 and 3.0 km/s, respectively. The depth to the basement layer is deeper in the Niigata port area located at the Japan sea side of the Niigata plain. In this area, the basement depth is about 4.8 km around the Seirou town and about 4.1 km around the Niigata city, respectively. These features about the basement depth in the Niigata plain are consistent with the previous surveys. In order to verify the profiles derived from microtremor array exploration, we estimate the group velocities of Love wave for four propagation paths of long-period earthquake ground motion during Niigata-ken tyuetsu earthquake by multiple filter technique, which were compared with the theoretical ones calculated from the derived profiles. As a result, it was confirmed that the group velocities from the derived profiles were in good agreement with the ones from long-period earthquake ground motion records during Niigata-ken tyuetsu earthquake. Furthermore, we applied the estimation method of design basis earthquake input for seismically isolated nuclear power facilities by using normal mode solution to estimate long-period earthquake ground motion during Niigata-ken tyuetsu earthquake. As a result, it was demonstrated that the applicability of the above method for the estimation of long-period earthquake ground motion were improved by using the derived 1D S-wave velocity profile. (author)

  17. Evaluation of linear array MOSFET detectors for in vivo dosimetry to measure rectal dose in HDR brachytherapy.

    Science.gov (United States)

    Haughey, Aisling; Coalter, George; Mugabe, Koki

    2011-09-01

    The study aimed to assess the suitability of linear array metal oxide semiconductor field effect transistor detectors (MOSFETs) as in vivo dosimeters to measure rectal dose in high dose rate brachytherapy treatments. The MOSFET arrays were calibrated with an Ir192 source and phantom measurements were performed to check agreement with the treatment planning system. The angular dependence, linearity and constancy of the detectors were evaluated. For in vivo measurements two sites were investigated, transperineal needle implants for prostate cancer and Fletcher suites for cervical cancer. The MOSFETs were inserted into the patients' rectum in theatre inside a modified flatus tube. The patients were then CT scanned for treatment planning. Measured rectal doses during treatment were compared with point dose measurements predicted by the TPS. The MOSFETs were found to require individual calibration factors. The calibration was found to drift by approximately 1% ±0.8 per 500 mV accumulated and varies with distance from source due to energy dependence. In vivo results for prostate patients found only 33% of measured doses agreed with the TPS within ±10%. For cervix cases 42% of measured doses agreed with the TPS within ±10%, however of those not agreeing variations of up to 70% were observed. One of the most limiting factors in this study was found to be the inability to prevent the MOSFET moving internally between the time of CT and treatment. Due to the many uncertainties associated with MOSFETs including calibration drift, angular dependence and the inability to know their exact position at the time of treatment, we consider them to be unsuitable for in vivo dosimetry in rectum for HDR brachytherapy.

  18. Evaluation of linear array MOSFET detectors for in vivo dosimetry to measure rectal dose in DHR brachytherapy

    International Nuclear Information System (INIS)

    Haughey, A.; Coalter, G.; Mugabe, K.

    2011-01-01

    Full text: The study aimed to assess the suitability of linear array metal oxide semiconductor field effect transistor detectors (MOSFETs) as in vivo dosimeters to measure rectal dose in high dose rate brachytherapy treatments. The MOSFET arrays were calibrated with an Ir192 source and phantom measurements were performed to check agreement with the treatment planning system. The angular dependence, linearity and constancy of the detectors were evaluated. For in vivo measurements two sites were investigated, transperineal needle implants for prostate cancer and Fletcher suites for cervical cancer. The MOSFETs were inserted into the patients' rectum in theatre inside a modified flatus tube. The patients were then CT scanned for treatment planning. Measured rectal doses during treatment were compared with point dose measurements predicted by the TPS. The MOSFETs were found to require individual calibration factors. The calibration was found to drift by approximately 1% ±0.8 per 500 mV accumulated and varies with distance from source due to energy dependence. In vivo results for prostate patients found only 33% of measured doses agreed with the TPS within ±1O%. For cervix cases 42% of measured doses agreed with the TPS within ± 10%, however of those not agreeing variations of up to 70% were observed. One of the most limiting factors in this study was found to be the inability to prevent the MOSFET moving internally between the time of CT and treatment. Due to the many uncertainties associated with MOSFETs including calibration drift, angular dependence and the inability to know their exact position at the time of treatment, we consider them to be unsuitable for in vivo dosimetry in rectum for HDR brachytherapy. (author)

  19. Wave Propagation in a coaxial waveguide with a periodic slot array

    CERN Document Server

    Alesini, D; Garganese, C; Migliorati, M; Palumbo, L

    2001-01-01

    In this paper we present the numerical and experimental study of the electromagnetic elds that propagate in a coaxial waveguide having periodic slots in the inner conductor. The aim of the work is to estimate the e ects of the holes on the phase velocity of the eld propagating in structures like the LHC liner, and to which extent these elds can be considered synchronous with the generating beam. To this end we have performed a numerical analysis by using the MAFIA simulation code, and have obtained, for a given geometry, the ampli- tude of the slowing down of the phase velocity due to the presence of the slot array. We have then performed a set of measurements of this e ect on a simple coaxial resonator, measuring the shift of the resonance frequencies produced by the slots. This shift, related to the phase velocity, has been compared with the results obtained with the simulations.

  20. Restoring Low Sidelobe Antenna Patterns with Failed Elements in a Phased Array Antenna

    Science.gov (United States)

    2016-02-01

    optimum low sidelobes are demonstrated in several examples. Index Terms — Array signal processing, beams, linear algebra , phased arrays, shaped...beam antennas. I. INTRODUCTION For many phased array antenna applications , low spatial sidelobes are required, and it is desirable to maintain...represented by a linear combination of low sidelobe beamformers with no failed elements, ’s, in a neighborhood around under the constraint that the linear

  1. An Improved Isotropic Periodic Sum Method That Uses Linear Combinations of Basis Potentials

    KAUST Repository

    Takahashi, Kazuaki Z.; Narumi, Tetsu; Suh, Donguk; Yasuoka, Kenji

    2012-01-01

    Isotropic periodic sum (IPS) is a technique that calculates long-range interactions differently than conventional lattice sum methods. The difference between IPS and lattice sum methods lies in the shape and distribution of remote images for long-range interaction calculations. The images used in lattice sum calculations are identical to those generated from periodic boundary conditions and are discretely positioned at lattice points in space. The images for IPS calculations are "imaginary", which means they do not explicitly exist in a simulation system and are distributed isotropically and periodically around each particle. Two different versions of the original IPS method exist. The IPSn method is applied to calculations for point charges, whereas the IPSp method calculates polar molecules. However, both IPSn and IPSp have their advantages and disadvantages in simulating bulk water or water-vapor interfacial systems. In bulk water systems, the cutoff radius effect of IPSn strongly affects the configuration, whereas IPSp does not provide adequate estimations of water-vapor interfacial systems unless very long cutoff radii are used. To extend the applicability of the IPS technique, an improved IPS method, which has better accuracy in both homogeneous and heterogeneous systems has been developed and named the linear-combination-based isotropic periodic sum (LIPS) method. This improved IPS method uses linear combinations of basis potentials. We performed molecular dynamics (MD) simulations of bulk water and water-vapor interfacial systems to evaluate the accuracy of the LIPS method. For bulk water systems, the LIPS method has better accuracy than IPSn in estimating thermodynamic and configurational properties without the countercharge assumption, which is used for IPSp. For water-vapor interfacial systems, LIPS has better accuracy than IPSp and properly estimates thermodynamic and configurational properties. In conclusion, the LIPS method can successfully estimate

  2. An Improved Isotropic Periodic Sum Method That Uses Linear Combinations of Basis Potentials

    KAUST Repository

    Takahashi, Kazuaki Z.

    2012-11-13

    Isotropic periodic sum (IPS) is a technique that calculates long-range interactions differently than conventional lattice sum methods. The difference between IPS and lattice sum methods lies in the shape and distribution of remote images for long-range interaction calculations. The images used in lattice sum calculations are identical to those generated from periodic boundary conditions and are discretely positioned at lattice points in space. The images for IPS calculations are "imaginary", which means they do not explicitly exist in a simulation system and are distributed isotropically and periodically around each particle. Two different versions of the original IPS method exist. The IPSn method is applied to calculations for point charges, whereas the IPSp method calculates polar molecules. However, both IPSn and IPSp have their advantages and disadvantages in simulating bulk water or water-vapor interfacial systems. In bulk water systems, the cutoff radius effect of IPSn strongly affects the configuration, whereas IPSp does not provide adequate estimations of water-vapor interfacial systems unless very long cutoff radii are used. To extend the applicability of the IPS technique, an improved IPS method, which has better accuracy in both homogeneous and heterogeneous systems has been developed and named the linear-combination-based isotropic periodic sum (LIPS) method. This improved IPS method uses linear combinations of basis potentials. We performed molecular dynamics (MD) simulations of bulk water and water-vapor interfacial systems to evaluate the accuracy of the LIPS method. For bulk water systems, the LIPS method has better accuracy than IPSn in estimating thermodynamic and configurational properties without the countercharge assumption, which is used for IPSp. For water-vapor interfacial systems, LIPS has better accuracy than IPSp and properly estimates thermodynamic and configurational properties. In conclusion, the LIPS method can successfully estimate

  3. Noise destroys the coexistence of periodic orbits of a piecewise linear map

    International Nuclear Information System (INIS)

    Wang Can-Jun; Yang Ke-Li; Qu Shi-Xian

    2013-01-01

    The effects of Gaussian white noise and Gaussian colored noise on the periodic orbits of period-5 (P-5) and period-6 (P-6) in their coexisting domain of a piecewise linear map are investigated numerically. The probability densities of some orbits are calculated. When the noise intensity is D = 0.0001, only the orbits of P-5 exist, and the coexisting phenomenon is destroyed. On the other hand, the self-correlation time τ of the colored noise also affects the coexisting phenomenon. When τ c c , only the orbits of P-5 appear, and the stability of the orbits of P-5 is enhanced. However, when τ > τ' c (τ c and τ c ' are critical values), only the orbits of P-6 exist, and the stability of the P-6 orbits is enhanced greatly. When τ c , the orbits of P-5 and P-6 coexist, but the stability of the P-5 orbits is enhanced and that of P-6 is weakened with τ increasing

  4. 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.

  5. Compact Spectrometers Based on Linear Variable Filters

    Data.gov (United States)

    National Aeronautics and Space Administration — Demonstrate a linear-variable spectrometer with an H2RG array. Linear Variable Filter (LVF) spectrometers provide attractive resource benefits – high optical...

  6. Photoacoustic technique for the characterization of plasmonic properties of 2D periodic arrays of gold nanoholes

    Directory of Open Access Journals (Sweden)

    E. Petronijevic

    2017-02-01

    Full Text Available We apply photo-acoustic (PA technique to examine plasmonic properties of 2D periodic arrays of nanoholes etched in gold/chromium layer upon a glass substrate. The pitch of these arrays lies in the near IR, and this, under appropriate wave vector matching conditions in the visible region, allows for the excitation of surface plasmon polaritons (SPP guided along a dielectric – metal surface. SPP offered new approaches in light guiding and local field intensity enhancement, but their detection is often difficult due to the problematic discrimination of their contribution from the overall scattering. Here PA measures the energy absorbed due to the non-radiative decay of SPPs. We report on the absorption enhancement by presenting the spatial mapping of absorption under the incidence angles and wavelength that correspond to the efficient excitation of SPPs. Moreover, a comparison with optical transmission measurements is carried out, underlining the applicability and sensitivity of PA technique.

  7. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  8. Linear Array Ultrasonic Testing Of A Thick Concrete Specimens For Non-Destructive Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dwight A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Khazanovich, Lev [Univ. of Minnesota, Minneapolis, MN (United States); Zammerachi, Mattia [Univ. of Minnesota, Minneapolis, MN (United States); Ezell, N. Dianne Bull [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-04-01

    The University of Minnesota and Oak Ridge National Laboratory are collaborating on the design and construction of a concrete specimen with sufficient reinforcement density and cross-sectional size to represent a light water reactor (LWR) containment wall with various defects. The preliminary analysis of the collected data using extended synthetic aperture focussin technique (SAFT) reconstruction indicated a great potential of the ultrasound array technology for locating relatively shallow distresses. However, the resolution and reliability of the analysis is inversely proportional to the defect depth and the amount of reinforcement between the measurement point and the defect location. The objective of this round of testing is to evaluate repeatability of the obtained reconstructions from measurements with different frequencies as well as to examine the effect of the duration of the sending ultrasound signal on the resulting reconstructions. Two series of testing are performed in this study. The objective of the first series is to evaluate repeatability of the measurements and resulting reconstructed images. The measurements use three center frequencies. Five measurements are performed at each location with and without lifting the device. The analysis of the collected data suggested that a linear array ultrasound system can produce reliably repeatable reconstructions using 50 kHz signals for relatively shallow depths (less than 0.5 m). However, for reconstructions at the greater depths the use of lower frequency and/or signal filtering to reduce the effect of signal noise may be required. The objective of the second series of testing is to obtain measurements with various impulse signal durations. The entire grid on the smooth surface is tested with four different various impulse signal durations. An analysis of the resulting extended SAFT reconstructions suggested that Kirchhoff-based migration leads to easier interpreting reconstructions when shorter duration

  9. Waveform correlation and coherence of short-period seismic noise within Gauribidanur array with implications for event detection

    International Nuclear Information System (INIS)

    Bhadauria, Y.S.; Arora, S.K.

    1995-01-01

    In continuation with our effort to model the short-period micro seismic noise at the seismic array at Gauribidanur (GBA), we have examined in detail time-correlation and spectral coherence of the noise field within the array space. This has implications of maximum possible improvement in signal-to-noise ratio (SNR) relevant to event detection. The basis of this study is about a hundred representative wide-band noise samples collected from GBA throughout the year 1992. Both time-structured correlation as well as coherence of the noise waveforms are found to be practically independent of the inter element distances within the array, and they exhibit strong temporal and spectral stability. It turns out that the noise is largely incoherent at frequencies ranging upwards from 2 Hz; the coherency coefficient tends to increase in the lower frequency range attaining a maximum of 0.6 close to 0.5 Hz. While the maximum absolute cross-correlation also diminishes with increasing frequency, the zero-lag cross-correlation is found to be insensitive to frequency filtering regardless of the pass band. An extremely small value of -0.01 of the zero-lag correlation and a comparatively higher year-round average estimate at 0.15 of the maximum absolute time-lagged correlation yields an SNR improvement varying between a probable high of 4.1 and a low of 2.3 for the full 20-element array. 19 refs., 6 figs

  10. A Series-Fed Linear Substrate-Integrated Dielectric Resonator Antenna Array for Millimeter-Wave Applications

    Directory of Open Access Journals (Sweden)

    Ke Gong

    2018-01-01

    Full Text Available A series-fed linear substrate-integrated dielectric resonator antenna array (SIDRAA is presented for millimeter-wave applications, in which the substrate-integrated dielectric resonator antenna (SIDRA elements and the feeding structure can be codesigned and fabricated using the same planar process. A prototype 4 × 1 SIDRAA is designed at Ka-band and fabricated with a two-layer printed circuit board (PCB technology. Four SIDRAs are implemented in the Rogers RT6010 substrate using the perforation technique and fed by a compact substrate-integrated waveguide (SIW through four longitudinal coupling slots within the Rogers RT5880 substrate. The return loss, radiation patterns, and antenna gain were experimentally studied, and good agreement between the measured and simulated results is observed. The SIDRAA example provides a bandwidth of about 10% around 34.5 GHz for 10 dB return loss and stable broadside radiation patterns with the peak gain of 10.5–11.5 dBi across the band.

  11. Microfabricated linear Paul-Straubel ion trap

    Science.gov (United States)

    Mangan, Michael A [Albuquerque, NM; Blain, Matthew G [Albuquerque, NM; Tigges, Chris P [Albuquerque, NM; Linker, Kevin L [Albuquerque, NM

    2011-04-19

    An array of microfabricated linear Paul-Straubel ion traps can be used for mass spectrometric applications. Each ion trap comprises two parallel inner RF electrodes and two parallel outer DC control electrodes symmetric about a central trap axis and suspended over an opening in a substrate. Neighboring ion traps in the array can share a common outer DC control electrode. The ions confined transversely by an RF quadrupole electric field potential well on the ion trap axis. The array can trap a wide array of ions.

  12. Sensor array signal processing

    CERN Document Server

    Naidu, Prabhakar S

    2009-01-01

    Chapter One: An Overview of Wavefields 1.1 Types of Wavefields and the Governing Equations 1.2 Wavefield in open space 1.3 Wavefield in bounded space 1.4 Stochastic wavefield 1.5 Multipath propagation 1.6 Propagation through random medium 1.7 ExercisesChapter Two: Sensor Array Systems 2.1 Uniform linear array (ULA) 2.2 Planar array 2.3 Distributed sensor array 2.4 Broadband sensor array 2.5 Source and sensor arrays 2.6 Multi-component sensor array2.7 ExercisesChapter Three: Frequency Wavenumber Processing 3.1 Digital filters in the w-k domain 3.2 Mapping of 1D into 2D filters 3.3 Multichannel Wiener filters 3.4 Wiener filters for ULA and UCA 3.5 Predictive noise cancellation 3.6 Exercises Chapter Four: Source Localization: Frequency Wavenumber Spectrum4.1 Frequency wavenumber spectrum 4.2 Beamformation 4.3 Capon's w-k spectrum 4.4 Maximum entropy w-k spectrum 4.5 Doppler-Azimuth Processing4.6 ExercisesChapter Five: Source Localization: Subspace Methods 5.1 Subspace methods (Narrowband) 5.2 Subspace methods (B...

  13. Fundamentals of ultrasonic phased arrays

    CERN Document Server

    Schmerr, Lester W

    2014-01-01

    This book describes in detail the physical and mathematical foundations of ultrasonic phased array measurements.?The book uses linear systems theory to develop a comprehensive model of the signals and images that can be formed with phased arrays. Engineers working in the field of ultrasonic nondestructive evaluation (NDE) will find in this approach a wealth of information on how to design, optimize and interpret ultrasonic inspections with phased arrays. The fundamentals and models described in the book will also be of significant interest to other fields, including the medical ultrasound and

  14. FEM-based linear inverse modeling using a 3D source array to image magma chambers with free geometry. Application to InSAR data from Rabaul Caldera (PNG).

    Science.gov (United States)

    Ronchin, Erika; Masterlark, Timothy; Dawson, John; Saunders, Steve; Martí Molist, Joan

    2015-04-01

    In this study, we present a method to fully integrate a family of finite element models (FEMs) into the regularized linear inversion of InSAR data collected at Rabaul caldera (PNG) between February 2007 and December 2010. During this period the caldera experienced a long-term steady subsidence that characterized surface movement both inside the caldera and outside, on its western side. The inversion is based on an array of FEM sources in the sense that the Green's function matrix is a library of forward numerical displacement solutions generated by the sources of an array common to all FEMs. Each entry of the library is the LOS surface displacement generated by injecting a unity mass of fluid, of known density and bulk modulus, into a different source cavity of the array for each FEM. By using FEMs, we are taking advantage of their capability of including topography and heterogeneous distribution of elastic material properties. All FEMs of the family share the same mesh in which only one source is activated at the time by removing the corresponding elements and applying the unity fluid flux. The domain therefore only needs to be discretized once. This precludes remeshing for each activated source, thus reducing computational requirements, often a downside of FEM-based inversions. Without imposing an a-priori source, the method allows us to identify, from a least-squares standpoint, a complex distribution of fluid flux (or change in pressure) with a 3D free geometry within the source array, as dictated by the data. The results of applying the proposed inversion to Rabaul InSAR data show a shallow magmatic system under the caldera made of two interconnected lobes located at the two opposite sides of the caldera. These lobes could be consistent with feeding reservoirs of the ongoing Tavuvur volcano eruption of andesitic products, on the eastern side, and of the past Vulcan volcano eruptions of more evolved materials, on the western side. The interconnection and

  15. Dual-polarization, wideband microstrip antenna array for airborne C-band SAR

    DEFF Research Database (Denmark)

    Granholm, Johan; Skou, Niels

    2000-01-01

    The paper describes the development of a C-band, dual linear polarization wideband antenna array, for use in the next-generation of the Danish airborne polarimetric synthetic aperture radar (SAR) system. The array is made of probe-fed, stacked microstrip patches. The design and performance of the...... of the basic stacked patch element, operating from 4.9 GHz to 5.7 GHz, and a 2×2 element test array of these, are described.......The paper describes the development of a C-band, dual linear polarization wideband antenna array, for use in the next-generation of the Danish airborne polarimetric synthetic aperture radar (SAR) system. The array is made of probe-fed, stacked microstrip patches. The design and performance...

  16. Matter-wave scattering and guiding by atomic arrays

    International Nuclear Information System (INIS)

    Vaishnav, J. Y.; Walls, J. D.; Apratim, M.; Heller, E. J.

    2007-01-01

    We investigate the possibility that linear arrays of atoms can guide matter waves, much as fiber optics guide light. We model the atomic line as a quasi-one-dimensional array of s-wave point scatterers embedded in two-dimensions. Our theoretical study reveals how matter-wave guiding arises from the interplay of scattering phenomena with bands and conduction along the array. We discuss the conditions under which a straight or curved array of atoms can guide a beam focused at one end of the array

  17. Halbach arrays in precision motion control

    Energy Technology Data Exchange (ETDEWEB)

    Trumper, D.L.; Williams, M.E. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-02-01

    The Halbach array was developed for use as an optical element in particle accelerators. Following up on a suggestion from Klaus Halbach, the authors have investigated the utility of such arrays as the permanent magnet structure for synchronous machines in cartesian, polar, and cylindrical geometries. Their work has focused on the design of a novel Halbach array linear motor for use in a magnetic suspension stage for photolithography. This paper presents the details of the motor design and its force and power characteristics.

  18. Fiber optic spectrophotometer with photodiode linear array

    International Nuclear Information System (INIS)

    Blanc, F.; Vernet, P.

    1988-01-01

    Spectrophotometric measurements are used in a great number of industrial processes, in nuclear environment and with optical precision components. Especially the evolution of a chemical process or of an optical coating could be followed by these measurements. Spectrophotometers, using optical fibers to transport the signal out of the instrument make possible the measurement ''in-situ'' and in real time. The advantage of using a diode array to detect the signal is an instantaneous measurement all over the spectral range without moving parts. It allows an excellent reproductibility. The instrument is controlled by a micro computer. The spectrophotometer is described and technical performance presented. An extension using optical fibers on a ''classical'' spectrophotometer (a H.P. one) is also described and technical performance presented

  19. Periodic arrays of deep nanopores made in silicon with reactive ion etching and deep UV lithography

    International Nuclear Information System (INIS)

    Woldering, Leon A; Tjerkstra, R Willem; Vos, Willem L; Jansen, Henri V; Setija, Irwan D

    2008-01-01

    We report on the fabrication of periodic arrays of deep nanopores with high aspect ratios in crystalline silicon. The radii and pitches of the pores were defined in a chromium mask by means of deep UV scan and step technology. The pores were etched with a reactive ion etching process with SF 6 , optimized for the formation of deep nanopores. We have realized structures with pitches between 440 and 750 nm, pore diameters between 310 and 515 nm, and depth to diameter aspect ratios up to 16. To the best of our knowledge, this is the highest aspect ratio ever reported for arrays of nanopores in silicon made with a reactive ion etching process. Our experimental results show that the etching rate of the nanopores is aspect-ratio-dependent, and is mostly influenced by the angular distribution of the etching ions. Furthermore we show both experimentally and theoretically that, for sub-micrometer structures, reducing the sidewall erosion is the best way to maximize the aspect ratio of the pores. Our structures have potential applications in chemical sensors, in the control of liquid wetting of surfaces, and as capacitors in high-frequency electronics. We demonstrate by means of optical reflectivity that our high-quality structures are very well suited as photonic crystals. Since the process studied is compatible with existing CMOS semiconductor fabrication, it allows for the incorporation of the etched arrays in silicon chips

  20. Phased array ultrasound testing on complex geometry

    International Nuclear Information System (INIS)

    Tuan Arif Tuan Mat; Khazali Mohd Zin

    2009-01-01

    Phase array ultrasonic inspection is used to investigate its response to complex welded joints geometry. A 5 MHz probe with 64 linear array elements was employed to scan mild steel T-joint, nozzle and node samples. These samples contain many defects such as cracks, lack of penetration and lack of fusion. Ultrasonic respond is analysed and viewed using the Tomoview software. The results show the actual phase array images on respective types of defect. (author)

  1. [A capillary blood flow velocity detection system based on linear array charge-coupled devices].

    Science.gov (United States)

    Zhou, Houming; Wang, Ruofeng; Dang, Qi; Yang, Li; Wang, Xiang

    2017-12-01

    In order to detect the flow characteristics of blood samples in the capillary, this paper introduces a blood flow velocity measurement system based on field-programmable gate array (FPGA), linear charge-coupled devices (CCD) and personal computer (PC) software structure. Based on the analysis of the TCD1703C and AD9826 device data sheets, Verilog HDL hardware description language was used to design and simulate the driver. Image signal acquisition and the extraction of the real-time edge information of the blood sample were carried out synchronously in the FPGA. Then a series of discrete displacement were performed in a differential operation to scan each of the blood samples displacement, so that the sample flow rate could be obtained. Finally, the feasibility of the blood flow velocity detection system was verified by simulation and debugging. After drawing the flow velocity curve and analyzing the velocity characteristics, the significance of measuring blood flow velocity is analyzed. The results show that the measurement of the system is less time-consuming and less complex than other flow rate monitoring schemes.

  2. Communication with spatial periodic chaos synchronization

    International Nuclear Information System (INIS)

    Zhou, J.; Huang, H.B.; Qi, G.X.; Yang, P.; Xie, X.

    2005-01-01

    Based on the spatial periodic chaos synchronization in coupled ring and linear arrays, we proposed a random high-dimensional chaotic encryption scheme. The transmitter can choose hyperchaotic signals randomly from the ring at any different time and simultaneously transmit the information of chaotic oscillators in the ring to receiver through public channel, so that the message can be masked by different hyperchaotic signals in different time intervals during communication, and the receiver can decode the message based on chaos synchronization but the attacker does not know the random hyperchaotic dynamics and cannot decode the message. Furthermore, the high sensitivity to the symmetry of the coupling structure makes the attacker very difficult to obtain any useful message from the channel

  3. Seismic Background Noise Analysis of BRTR (PS-43) Array

    Science.gov (United States)

    Ezgi Bakir, Mahmure; Meral Ozel, Nurcan; Umut Semin, Korhan

    2015-04-01

    The seismic background noise variation of BRTR array, composed of two sub arrays located in Ankara and in Ankara-Keskin, has been investigated by calculating Power Spectral Density and Probability Density Functions for seasonal and diurnal noise variations between 2005 and 2011. PSDs were computed within the frequency range of 100 s - 10 Hz. The results show us a little change in noise conditions in terms of time and location. Especially, noise level changes were observed at 3-5 Hz in diurnal variations at Keskin array and there is a 5-7 dB difference in day and night time in cultural noise band (1-10 Hz). On the other hand, noise levels of medium period array is high in 1-2 Hz frequency rather than short period array. High noise levels were observed in daily working times when we compare it to night-time in cultural noise band. The seasonal background noise variation at both sites also shows very similar properties to each other. Since these stations are borehole instruments and away from the coasts, we saw a small change in noise levels caused by microseism. Comparison between Keskin short period array and Ankara medium period array show us Keskin array is quiter than Ankara array.

  4. Equivalent-circuit model for stacked slot-based 2D periodic arrays of arbitrary geometry for broadband analysis

    Science.gov (United States)

    Astorino, Maria Denise; Frezza, Fabrizio; Tedeschi, Nicola

    2018-03-01

    The analysis of the transmission and reflection spectra of stacked slot-based 2D periodic structures of arbitrary geometry and the ability to devise and control their electromagnetic responses have been a matter of extensive research for many decades. The purpose of this paper is to develop an equivalent Π circuit model based on the transmission-line theory and Floquet harmonic interactions, for broadband and short longitudinal period analysis. The proposed circuit model overcomes the limits of identical and symmetrical configurations imposed by the even/odd excitation approach, exploiting both the circuit topology of a single 2D periodic array of apertures and the ABCD matrix formalism. The transmission spectra obtained through the equivalent-circuit model have been validated by comparison with full-wave simulations carried out with a finite-element commercial electromagnetic solver. This allowed for a physical insight into the spectral and angular responses of multilayer devices with arbitrary aperture shapes, guaranteeing a noticeable saving of computational resources.

  5. Sparse Array Angle Estimation Using Reduced-Dimension ESPRIT-MUSIC in MIMO Radar

    Directory of Open Access Journals (Sweden)

    Chaozhu Zhang

    2013-01-01

    Full Text Available Sparse linear arrays provide better performance than the filled linear arrays in terms of angle estimation and resolution with reduced size and low cost. However, they are subject to manifold ambiguity. In this paper, both the transmit array and receive array are sparse linear arrays in the bistatic MIMO radar. Firstly, we present an ESPRIT-MUSIC method in which ESPRIT algorithm is used to obtain ambiguous angle estimates. The disambiguation algorithm uses MUSIC-based procedure to identify the true direction cosine estimate from a set of ambiguous candidate estimates. The paired transmit angle and receive angle can be estimated and the manifold ambiguity can be solved. However, the proposed algorithm has high computational complexity due to the requirement of two-dimension search. Further, the Reduced-Dimension ESPRIT-MUSIC (RD-ESPRIT-MUSIC is proposed to reduce the complexity of the algorithm. And the RD-ESPRIT-MUSIC only demands one-dimension search. Simulation results demonstrate the effectiveness of the method.

  6. Sparse array angle estimation using reduced-dimension ESPRIT-MUSIC in MIMO radar.

    Science.gov (United States)

    Zhang, Chaozhu; Pang, Yucai

    2013-01-01

    Sparse linear arrays provide better performance than the filled linear arrays in terms of angle estimation and resolution with reduced size and low cost. However, they are subject to manifold ambiguity. In this paper, both the transmit array and receive array are sparse linear arrays in the bistatic MIMO radar. Firstly, we present an ESPRIT-MUSIC method in which ESPRIT algorithm is used to obtain ambiguous angle estimates. The disambiguation algorithm uses MUSIC-based procedure to identify the true direction cosine estimate from a set of ambiguous candidate estimates. The paired transmit angle and receive angle can be estimated and the manifold ambiguity can be solved. However, the proposed algorithm has high computational complexity due to the requirement of two-dimension search. Further, the Reduced-Dimension ESPRIT-MUSIC (RD-ESPRIT-MUSIC) is proposed to reduce the complexity of the algorithm. And the RD-ESPRIT-MUSIC only demands one-dimension search. Simulation results demonstrate the effectiveness of the method.

  7. 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)

  8. Periodic array-based substrates for surface-enhanced infrared spectroscopy

    Science.gov (United States)

    Mayerhöfer, Thomas G.; Popp, Jürgen

    2018-01-01

    At the beginning of the 1980s, the first reports of surface-enhanced infrared spectroscopy (SEIRS) surfaced. Probably due to signal-enhancement factors of only 101 to 103, which are modest compared to those of surface-enhanced Raman spectroscopy (SERS), SEIRS did not reach the same significance up to date. However, taking the compared to Raman scattering much larger cross-sections of infrared absorptions and the enhancement factors together, SEIRS reaches about the same sensitivity for molecular species on a surface in terms of the cross-sections as SERS and, due to the complementary nature of both techniques, can valuably augment information gained by SERS. For the first 20 years since its discovery, SEIRS relied completely on metal island films, fabricated by either vapor or electrochemical deposition. The resulting films showed a strong variance concerning their structure, which was essentially random. Therefore, the increase in the corresponding signal-enhancement factors of these structures stagnated in the last years. In the very same years, however, the development of periodic array-based substrates helped SEIRS to gather momentum. This development was supported by technological progress concerning electromagnetic field solvers, which help to understand plasmonic properties and allow targeted design. In addition, the strong progress concerning modern fabrication methods allowed to implement these designs into practice. The aim of this contribution is to critically review the development of these engineered surfaces for SEIRS, to compare the different approaches with regard to their performance where possible, and report further gain of knowledge around and in relation to these structures.

  9. Vortex lattice in effective type-I superconducting films with periodic arrays of submicron holes

    International Nuclear Information System (INIS)

    Berdiyorov, G.R.; Milosevic, M.V.; Peeters, F.M.

    2006-01-01

    The vortex matter and related phenomena in superconducting films with periodic arrays of microholes (antidots) are studied within the nonlinear Ginzburg-Landau (GL) theory. By varying the GL parameter κ, the vortex-vortex interaction is fine tuned, from repulsive to attractive behavior. This interaction is of crucial importance for equilibrium vortex structures, the saturation number of the antidots, and the related quantities, such as critical current. Due to vortex attraction in effectively type-I samples, the giant-vortex state becomes energetically favorable (contrary to the type-II behavior). For the same reason, the number of vortices which can be captured by antidots, increases with decreasing κ. As a result, for given magnetic field, the critical current is larger for effectively type-I superconductors than in conventional type-II cases

  10. Acoustic field of focusing phased array probe and the scanning system

    International Nuclear Information System (INIS)

    Murai, J.; Miura, S.; Ida, T.; Shiraiwa, T.; Miya, T.

    1997-01-01

    Acoustic field of a point focusing cylindrical linear array probe, in which focusing in the axial direction of cylinder is done by the phased linear array and focusing in the orthogonal direction is done geometrically, was studied by numerical calculation and an optimum design of phased array probe for focusing has been obtained. In generally speaking, the beam width at focus point decreases with decrease of width of each transducer element and with increase of synthetic aperture made by total elements. If the number of total array elements excited as one pulse is limited, the above conditions are contradicted. Thus, an optimum element width exists for the best focusing. On the above consideration, we can get focusing ability of phased array nearly as same as geometrical focusing. A developed transducer is a linear array of polymer piezoelectric material of cylindrical shape, of which radius is from 50 mm to 75 mm. The frequency is 10 Mhz and the beam width of 0.5 mm (depending on aperture) in the orthogonal direction to the cylinder axis and 0.7 mm width in the cylinder axis (phased array focusing) have been obtained. A delay circuit for exciting the transducer was newly designed to give maximum performance to the array regarding to accuracy, stability, easy control and etc. A c-scan ultrasonic testing system equipped with this transducer has sixteen times inspection speed compared to the single probe instrument.

  11. 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.

  12. Oscillations of a Beam on a Non-Linear Elastic Foundation under Periodic Loads

    Directory of Open Access Journals (Sweden)

    Donald Mark Santee

    2006-01-01

    Full Text Available The complexity of the response of a beam resting on a nonlinear elastic foundation makes the design of this structural element rather challenging. Particularly because, apparently, there is no algebraic relation for its load bearing capacity as a function of the problem parameters. Such an algebraic relation would be desirable for design purposes. Our aim is to obtain this relation explicitly. Initially, a mathematical model of a flexible beam resting on a non-linear elastic foundation is presented, and its non-linear vibrations and instabilities are investigated using several numerical methods. At a second stage, a parametric study is carried out, using analytical and semi-analytical perturbation methods. So, the influence of the various physical and geometrical parameters of the mathematical model on the non-linear response of the beam is evaluated, in particular, the relation between the natural frequency and the vibration amplitude and the first period doubling and saddle-node bifurcations. These two instability phenomena are the two basic mechanisms associated with the loss of stability of the beam. Finally Melnikov's method is used to determine an algebraic expression for the boundary that separates a safe from an unsafe region in the force parameters space. It is shown that this can be used as a basis for a reliable engineering design criterion.

  13. Topology optimization of Halbach magnet arrays using isoparametric projection

    International Nuclear Information System (INIS)

    Lee, Jaewook; Nomura, Tsuyoshi; Dede, Ercan M.

    2017-01-01

    Highlights: • Design method of Halbach magnet array is proposed using topology optimization. • Magnet strength and direction are simultaneously optimized by isoparametric projection. • For manufacturing feasibility of magnet, penalization and extrusion schemes are proposed. • Design results of circular shaped Halbach arrays are provided. • Halbach arrays in linear actuator are optimized to maximize magnetic force. - Abstract: Topology optimization using isoparametric projection for the design of permanent magnet patterns in Halbach arrays is proposed. Based on isoparametric shape functions used in the finite element analysis, the permanent magnet strength and magnetization directions in a Halbach array are simultaneously optimized for a given design goal. To achieve fabrication feasibility of a designed Halbach magnet array, two design schemes are combined with the isoparametric projection method. First, a penalization scheme is proposed for designing the permanent magnets to have discrete magnetization direction angles. Second, an extrusion scheme is proposed for the shape regularization of the permanent magnet segments. As a result, the method systematically finds the optimal permanent magnet patterns of a Halbach array considering manufacturing feasibility. In two numerical examples, a circular shaped permanent magnet Halbach array is designed to minimize the magnitude of the magnetic flux density and to maximize the upward direction magnetic flux density inside the magnet array. Logical extension of the method to the design of permanent magnet arrays in linear actuators is provided, where the design goal is to maximize the actuator magnetic force.

  14. Topology optimization of Halbach magnet arrays using isoparametric projection

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaewook, E-mail: jaewooklee@gist.ac.kr [School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005 (Korea, Republic of); Nomura, Tsuyoshi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Aichi 480-1192 (Japan); Toyota Research Institute of North America, 1555 Woodridge Avenue, Ann Arbor, MI 48105 (United States); Dede, Ercan M. [Toyota Research Institute of North America, 1555 Woodridge Avenue, Ann Arbor, MI 48105 (United States)

    2017-06-15

    Highlights: • Design method of Halbach magnet array is proposed using topology optimization. • Magnet strength and direction are simultaneously optimized by isoparametric projection. • For manufacturing feasibility of magnet, penalization and extrusion schemes are proposed. • Design results of circular shaped Halbach arrays are provided. • Halbach arrays in linear actuator are optimized to maximize magnetic force. - Abstract: Topology optimization using isoparametric projection for the design of permanent magnet patterns in Halbach arrays is proposed. Based on isoparametric shape functions used in the finite element analysis, the permanent magnet strength and magnetization directions in a Halbach array are simultaneously optimized for a given design goal. To achieve fabrication feasibility of a designed Halbach magnet array, two design schemes are combined with the isoparametric projection method. First, a penalization scheme is proposed for designing the permanent magnets to have discrete magnetization direction angles. Second, an extrusion scheme is proposed for the shape regularization of the permanent magnet segments. As a result, the method systematically finds the optimal permanent magnet patterns of a Halbach array considering manufacturing feasibility. In two numerical examples, a circular shaped permanent magnet Halbach array is designed to minimize the magnitude of the magnetic flux density and to maximize the upward direction magnetic flux density inside the magnet array. Logical extension of the method to the design of permanent magnet arrays in linear actuators is provided, where the design goal is to maximize the actuator magnetic force.

  15. Numerical computing of elastic homogenized coefficients for periodic fibrous tissue

    Directory of Open Access Journals (Sweden)

    Roman S.

    2009-06-01

    Full Text Available The homogenization theory in linear elasticity is applied to a periodic array of cylindrical inclusions in rectangular pattern extending to infinity in the inclusions axial direction, such that the deformation of tissue along this last direction is negligible. In the plane of deformation, the homogenization scheme is based on the average strain energy whereas in the third direction it is based on the average normal stress along this direction. Namely, these average quantities have to be the same on a Repeating Unit Cell (RUC of heterogeneous and homogenized media when using a special form of boundary conditions forming by a periodic part and an affine part of displacement. It exists an infinity of RUCs generating the considered array. The computing procedure is tested with different choices of RUC to control that the results of the homogenization process are independent of the kind of RUC we employ. Then, the dependence of the homogenized coefficients on the microstructure can be studied. For instance, a special anisotropy and the role of the inclusion volume are investigated. In the second part of this work, mechanical traction tests are simulated. We consider two kinds of loading, applying a density of force or imposing a displacement. We test five samples of periodic array containing one, four, sixteen, sixty-four and one hundred of RUCs. The evolution of mean stresses, strains and energy with the numbers of inclusions is studied. Evolutions depend on the kind of loading, but not their limits, which could be predicted by simulating traction test of the homogenized medium.

  16. 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.

  17. Bearing estimation with acoustic vector-sensor arrays

    International Nuclear Information System (INIS)

    Hawkes, M.; Nehorai, A.

    1996-01-01

    We consider direction-of-arrival (DOA) estimation using arrays of acoustic vector sensors in free space, and derive expressions for the Cramacute er-Rao bound on the DOA parameters when there is a single source. The vector-sensor array is seen to have improved performance over the traditional scalar-sensor (pressure-sensor) array for two distinct reasons: its elements have an inherent directional sensitivity and the array makes a greater number of measurements. The improvement is greatest for small array apertures and low signal-to-noise ratios. Examination of the conventional beamforming and Capon DOA estimators shows that vector-sensor arrays can completely resolve the bearing, even with a linear array, and can remove the ambiguities associated with spatial undersampling. We also propose and analyze a diversely-oriented array of velocity sensors that possesses some of the advantages of the vector-sensor array without the increase in hardware and computation. In addition, in certain scenarios it can avoid problems with spatially correlated noise that the vector-sensor array may suffer. copyright 1996 American Institute of Physics

  18. Ultrasonographic findings of breast diseases during pregnancy and lactating period

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yeon Hee [Dnakook University College of Medicine, Cheonan (Korea, Republic of); Park, Yong Hyun; Kwon, Tae Hee [Cha Women' s Hospital of Seoul, Seoul (Korea, Republic of)

    1995-09-15

    To evaluate ultrasonographic findings and usefulness in the diagnosis of breast diseases during pregnancy and lactating period. The authors evaluated the ultrasonographic findings of 18 breast diseases during pregnancy and lactation retrospectively. The ultrasonographic examinations were performed with linear-array 5 MHz transducer (ATL). Final diagnoses were obtained by the excisional biopsy, fine needle aspiration and clinical follow-up. Total 18 cases of breast diseases were consisted of 8 cases of galactocele, 4 cases of fibroadenoma, 3 cases of axillary accessory breast, 2 cases of lactating adenoma, and 1 case of phylloides tumor. The ultrasonographic findings of the above breast diseases were valuable in the diagnosis and therapeutic planning. Ultrasonography is the initial and useful method of diagnosing breast diseases during pregnancy and lactating period.

  19. Ultrasonographic findings of breast diseases during pregnancy and lactating period

    International Nuclear Information System (INIS)

    Lee, Yeon Hee; Park, Yong Hyun; Kwon, Tae Hee

    1995-01-01

    To evaluate ultrasonographic findings and usefulness in the diagnosis of breast diseases during pregnancy and lactating period. The authors evaluated the ultrasonographic findings of 18 breast diseases during pregnancy and lactation retrospectively. The ultrasonographic examinations were performed with linear-array 5 MHz transducer (ATL). Final diagnoses were obtained by the excisional biopsy, fine needle aspiration and clinical follow-up. Total 18 cases of breast diseases were consisted of 8 cases of galactocele, 4 cases of fibroadenoma, 3 cases of axillary accessory breast, 2 cases of lactating adenoma, and 1 case of phylloides tumor. The ultrasonographic findings of the above breast diseases were valuable in the diagnosis and therapeutic planning. Ultrasonography is the initial and useful method of diagnosing breast diseases during pregnancy and lactating period

  20. Controlled growth of periodically aligned copper-silicide nanocrystal arrays on silicon directed by laser-induced periodic surface structures (LIPSS)

    Science.gov (United States)

    Nürnberger, Philipp; Reinhardt, Hendrik M.; Rhinow, Daniel; Riedel, René; Werner, Simon; Hampp, Norbert A.

    2017-10-01

    In this paper we introduce a versatile tool for the controlled growth and alignment of copper-silicide nanocrystals. The method takes advantage of a unique self-organization phenomenon denoted as laser-induced periodic surface structures (LIPSS). Copper films (3 ± 0.2 nm) are sputter-deposited onto single crystal silicon (100) substrates with a thin oxide layer (4 ± 0.2 nm), and subsequently exposed to linearly polarized nanosecond laser pulses (τ ≈ 6 ns) at a central wavelength of 532 nm. The irradiation triggers dewetting of the Cu film and simultaneous formation of periodic Cu nanowires (LIPSS), which partially penetrate the oxide layer to the Si substrate. These LIPSS act as nucleation centers for the growth of Cu-Si crystals during thermal processing at 500 °C under forming gas 95/5 atmosphere. Exemplified by our model system Cu/SiO2/Si, LIPSS are demonstrated to facilitate the diffusion reaction between Cu and underlying Si. Moreover, adjustment of the laser polarization allows us to precisely control the nanocrystal alignment with respect to the LIPSS orientation. Potential applications and conceivable alternatives of this process are discussed.

  1. Development of portable phased array UT system for real-time flaw imaging

    International Nuclear Information System (INIS)

    Goto, M.

    1995-01-01

    Many functions and features of phased array UT technology must be useful for NDE in the industrial field. Some phased array UT systems have been developed for the inspection of nuclear pressure vessel and turbine components. However, phased array UT is still a special NDE technique and it has not been used widely in the past. The reasons of that are system size, cost, operator performance, equipment design and others. TOSHIBA has newly developed PC controlled portable phased array system to solve those problems. The portable phased array UT system is very compact and light but it is able to drive up to 32-channel linear array probe, to display real-time linear/sector B-scan, to display accumulated B-scan with an encoder and to display profile overlaid B-scan. The first applications were turbine component inspections for precise flaw investigation and flaw image data recording

  2. Asymptotics of linear initial boundary value problems with periodic boundary data on the half-line and finite intervals

    KAUST Repository

    Dujardin, G. M.

    2009-01-01

    This paper deals with the asymptotic behaviour of the solutions of linear initial boundary value problems with constant coefficients on the half-line and on finite intervals. We assume that the boundary data are periodic in time and we investigate

  3. Ordered arrays of nanoporous gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2012-09-01

    Full Text Available A combination of a “top-down” approach (substrate-conformal imprint lithography and two “bottom-up” approaches (dewetting and dealloying enables fabrication of perfectly ordered 2-dimensional arrays of nanoporous gold nanoparticles. The dewetting of Au/Ag bilayers on the periodically prepatterned substrates leads to the interdiffusion of Au and Ag and the formation of an array of Au–Ag alloy nanoparticles. The array of alloy nanoparticles is transformed into an array of nanoporous gold nanoparticles by a following dealloying step. Large areas of this new type of material arrangement can be realized with this technique. In addition, this technique allows for the control of particle size, particle spacing, and ligament size (or pore size by varying the period of the structure, total metal layer thickness, and the thickness ratio of the as-deposited bilayers.

  4. Dumand-array data-acquisition system

    International Nuclear Information System (INIS)

    Brenner, A.E.; Theriot, D.; Dau, W.D.; Geelhood, B.D.; Harris, F.; Learned, J.G.; Stenger, V.; March, R.; Roos, C.; Shumard, E.

    1982-04-01

    An overall data acquisition approach for DUMAND is described. The scheme assumes one array to shore optical fiber transmission line for each string of the array. The basic event sampling period is approx. 13 μsec. All potentially interesting data is transmitted to shore where the major processing is performed

  5. On the existence of eigenmodes of linear quasi-periodic differential equations and their relation to the MHD continuum

    International Nuclear Information System (INIS)

    Salat, A.

    1981-12-01

    The existence of quasi-periodic eigensolutions of a linear second order ordinary differential equation with quasi-periodic coefficient f(ω 1 t,ω 2 t) is investigated numerically and graphically. For sufficiently incommensurate frequencies ω 1 , ω 2 a doubly indexed infinite sequence of eigenvalues and eigenmodes is obtained. The equation considered is a model for the magneto-hydrodynamic 'continuum' in general toroidal geometry. The result suggests that continuum modes exist at least on sufficiently irrational magnetic surfaces. (orig.)

  6. 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.

  7. Dynamic optimal control of groundwater remediation with management periods: Linearized and quasi-Newton approaches

    International Nuclear Information System (INIS)

    Culver, T.B.

    1991-01-01

    Several modifications of the linear-quadratic regulator (LQR) optimization algorithm are developed, and the computational efficiency of each algorithm with respect to groundwater remediation is evaluated. In each case, the optimization model is combined with a finite element groundwater flow and transport simulation model to determine the optimal time-varying pump-and-treat policy. The first modification of the LQR algorithm incorporated management periods, which are groups of simulation time steps during which the pumping policy remains constant. Management periods reduced the total computational demand, as measured by the CPU time, by as much as 85% compared to the time needed for the LQR solution without management periods. Complexity analysis revealed that computational savings of equal or greater magnitude can be expected in general for groundwater remediation applications and for many other applications of dynamic control. The LQR algorithm with management periods was further modified by assuming steady-state hydraulics within a management period (SSLQR), which simplifies the derivatives of the transition equation. A quasi-Newton differential dynamic programming (QNDDP) was formulated by approximating the complicated second derivatives of the transition equation using a Broyden rank-one approximation. QNDDP converged to the optimal policy for the test problem significantly faster than the LQR algorithm, requiring approximately half the computational time. With the test problem expanded to include the capacity of the treatment facility as a state variable, QNDDP with management periods can determine the optimal treatment facility capacity. With many management periods, the addition of the capital costs of the treatment facility changed the optimal policy so that the required treatment facility capacity was reduced

  8. Measurement of changes in linear accelerator photon energy through flatness variation using an ion chamber array

    International Nuclear Information System (INIS)

    Gao Song; Balter, Peter A.; Rose, Mark; Simon, William E.

    2013-01-01

    Purpose: To compare the use of flatness versus percent depth dose (PDD) for determining changes in photon beam energy for a megavoltage linear accelerator. Methods: Energy changes were accomplished by adjusting the bending magnet current by up to ±15% in 5% increments away from the value used clinically. Two metrics for flatness, relative flatness in the central 80% of the field (Flat) and average maximum dose along the diagonals normalized by central axis dose (F DN ), were measured using a commercially available planner ionization chamber array. PDD was measured in water at depths of 5 and 10 cm in 3 × 3 cm 2 and 10 × 10 cm 2 fields using a cylindrical chamber. Results: PDD was more sensitive to changes in energy when the beam energy was increased than when it was decreased. For the 18-MV beam in particular, PDD was not sensitive to energy reductions below the nominal energy. The value of Flat was found to be more sensitive to decreases in energy than to increases, with little sensitivity to energy increases above the nominal energy for 18-MV beams. F DN was the only metric that was found to be sensitive to both increases and reductions of energy for both the 6- and 18-MV beams. Conclusions: Flatness based metrics were found to be more sensitive to energy changes than PDD, In particular, F DN was found to be the most sensitive metric to energy changes for photon beams of 6 and 18 MV. The ionization chamber array allows this metric to be conveniently measured as part of routine accelerator quality assurance.

  9. Detector array and method

    International Nuclear Information System (INIS)

    Timothy, J.G.; Bybee, R.L.

    1978-01-01

    A detector array and method are described in which sets of electrode elements are provided. Each set consists of a number of linear extending parallel electrodes. The sets of electrode elements are disposed at an angle (preferably orthogonal) with respect to one another so that the individual elements intersect and overlap individual elements of the other sets. Electrical insulation is provided between the overlapping elements. The detector array is exposed to a source of charged particles which in accordance with one embodiment comprise electrons derived from a microchannel array plate exposed to photons. Amplifier and discriminator means are provided for each individual electrode element. Detection means are provided to sense pulses on individual electrode elements in the sets, with coincidence of pulses on individual intersecting electrode elements being indicative of charged particle impact at the intersection of the elements. Electronic readout means provide an indication of coincident events and the location where the charged particle or particles impacted. Display means are provided for generating appropriate displays representative of the intensity and locaton of charged particles impacting on the detector array

  10. Tunable silver-shell dielectric core nano-beads array for thin-film solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Chou Chau, Yuan-Fong, E-mail: a0920146302@gmail.com, E-mail: chou.fong@ubd.edu.bn; Lim, Chee Ming [Universiti Brunei Darussalam, Centre for Advanced Material and Energy Sciences (Brunei) (Brunei Darussalam); Chiang, Chien-Ying [National Taipei University of Technology, Department of Electro-Optical Engineering (China); Voo, Nyuk Yoong; Muhammad Idris, Nur Syafi’ie; Chai, Siew Ung [Universiti Brunei Darussalam, Centre for Advanced Material and Energy Sciences (Brunei) (Brunei Darussalam)

    2016-04-15

    The absorbance spectra of thin-film solar cells (TFSCs) can be enhanced by constructing the tunable periodic Ag-shell nano-bead (PASNB) arrays in the active material. In this paper, we investigated a plasmonic thin-film solar cell (TFSC) which composed of the arrays of PASNB deposited onto a crystalline silicon layer. By performing three-dimensional finite element method, we demonstrate that near field coupling among the PASNB arrays results in SPR modes with enhanced absorbance and field intensity. The proposed structure can significantly enhance the plasmonic activity in a wide range of incident light and enlarge working wavelength of absorbance in the range of near-UV, visible and near-infrared. We show that the sensitivity of the PASNB arrays reveals a linear relationship with the thickness of Ag-shell nano-bead (ASNB) for both the anti-bonding and bonding modes in the absorbance spectra. The broadband of absorbance spectra could be expanded as a wide range by varying the thickness of ASNB while the particle size is kept constant. Simulation results suggest this alternative scheme to the design and improvements on plasmonic enhanced TFSCs can be extended to other nanophotonic applications.

  11. Singular formalism and admissible control of spacecraft with rotating flexible solar array

    Directory of Open Access Journals (Sweden)

    Lu Dongning

    2014-02-01

    Full Text Available This paper is concerned with the attitude control of a three-axis-stabilized spacecraft which consists of a central rigid body and a flexible sun-tracking solar array driven by a solar array drive assembly. Based on the linearization of the dynamics of the spacecraft and the modal identities about the flexible and rigid coupling matrices, the spacecraft attitude dynamics is reduced to a formally singular system with periodically varying parameters, which is quite different from a spacecraft with fixed appendages. In the framework of the singular control theory, the regularity and impulse-freeness of the singular system is analyzed and then admissible attitude controllers are designed by Lyapunov’s method. To improve the robustness against system uncertainties, an H∞ optimal control is designed by optimizing the H∞ norm of the system transfer function matrix. Comparative numerical experiments are performed to verify the theoretical results.

  12. Linearization Method and Linear Complexity

    Science.gov (United States)

    Tanaka, Hidema

    We focus on the relationship between the linearization method and linear complexity and show that the linearization method is another effective technique for calculating linear complexity. We analyze its effectiveness by comparing with the logic circuit method. We compare the relevant conditions and necessary computational cost with those of the Berlekamp-Massey algorithm and the Games-Chan algorithm. The significant property of a linearization method is that it needs no output sequence from a pseudo-random number generator (PRNG) because it calculates linear complexity using the algebraic expression of its algorithm. When a PRNG has n [bit] stages (registers or internal states), the necessary computational cost is smaller than O(2n). On the other hand, the Berlekamp-Massey algorithm needs O(N2) where N(≅2n) denotes period. Since existing methods calculate using the output sequence, an initial value of PRNG influences a resultant value of linear complexity. Therefore, a linear complexity is generally given as an estimate value. On the other hand, a linearization method calculates from an algorithm of PRNG, it can determine the lower bound of linear complexity.

  13. MOS solid-state detector arrays for x-ray imaging

    International Nuclear Information System (INIS)

    Koppel, L.N.

    1977-01-01

    Two types of MOS detector arrays were used to sense directly patterns of soft x-rays, in the Lawrence Livermore Laboratory experimental laser-fusion program. A linear self-scanning photodiode array (SSPA) is used in a wave-length-dispersive spectrometer. A frame transfer charge-coupled device (CCD) facilitates the use of an x-ray microscope. Measurements and calculations of the x-ray sensitivity of these devices are presented. Their linearity and dynamic range are discussed, as well as data recovery systems for each detector. Experiences in using these devices to detect pulses of x-rays in laser-fusion experiments are described

  14. 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...

  15. Experimental Validation of a Wave Energy Converter Array Hydrodynamics Tool

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Ferri, Francesco; Kofoed, Jens Peter

    2017-01-01

    This paper uses experimental data to validate a wave energy converter (WEC) array hydrodynamics tool developed within the context of linearized potential flow theory. To this end, wave forces and power absorption by an array of five-point absorber WECs in monochromatic and panchromatic waves were...

  16. 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.

  17. THE McELIECE CRYPTOSYSTEM WITH ARRAY CODES

    Directory of Open Access Journals (Sweden)

    Vedat Şiap

    2011-12-01

    Full Text Available Public-key cryptosystems form an important part of cryptography. In these systems, every user has a public and a private key. The public key allows other users to encrypt messages, which can only be decoded using the secret private key. In that way, public-key cryptosystems allow easy and secure communication between all users without the need to actually meet and exchange keys. One such system is the McEliece Public-Key cryptosystem, sometimes also called McEliece Scheme. However, as we live in the information age, coding is used in order to protecet or correct the messages in the transferring or the storing processes. So, linear codes are important in the transferring or the storing. Due to richness of their structure array codes which are linear are also an important codes. However, the information is then transferred into the source more securely by increasing the error correction capability with array codes. In this paper, we combine two interesting topics, McEliece cryptosystem and array codes.

  18. The structure of mode-locking regions of piecewise-linear continuous maps: II. Skew sawtooth maps

    Science.gov (United States)

    Simpson, D. J. W.

    2018-05-01

    In two-parameter bifurcation diagrams of piecewise-linear continuous maps on , mode-locking regions typically have points of zero width known as shrinking points. Near any shrinking point, but outside the associated mode-locking region, a significant proportion of parameter space can be usefully partitioned into a two-dimensional array of annular sectors. The purpose of this paper is to show that in these sectors the dynamics is well-approximated by a three-parameter family of skew sawtooth circle maps, where the relationship between the skew sawtooth maps and the N-dimensional map is fixed within each sector. The skew sawtooth maps are continuous, degree-one, and piecewise-linear, with two different slopes. They approximate the stable dynamics of the N-dimensional map with an error that goes to zero with the distance from the shrinking point. The results explain the complicated radial pattern of periodic, quasi-periodic, and chaotic dynamics that occurs near shrinking points.

  19. Demonstration of Millimeter Wave 5G Setup Employing High-Gain Vivaldi Array

    Directory of Open Access Journals (Sweden)

    Waleed Tariq Sethi

    2018-01-01

    Full Text Available We present a 4 × 4 slot-coupled Vivaldi antenna (SCVA array unit cell, which offers wide bandwidth and high gain (~23 dBi at the millimeter wave (mmW frequencies of 28 GHz and 38 GHz. A single SCVA element is first presented, which has a bandwidth of 25–40 GHz with an average gain of ~13 dBi at the frequencies of interest. This antenna element is then used to design a 1 × 4 linear SCVA array matched to a 50 Ω impedance via a modified Wilkinson power divider (WPD. Next, the 1 × 4 linear array is used to construct a 4 × 4 antenna array unit cell. The proposed 4 × 4 antenna array unit cell is fabricated, and the characteristics of its elements (i.e., the single SCVA, 1 × 4 linear array, and WPD are thoroughly investigated. Further, the 4 × 4 array is tested for signal reception of various digital modulation formats at lab environment using high-speed digital signal oscilloscope. In particular, a 2.5 Gbps data rate is successfully transmitted achieving receiver sensitivity of −50 dBm at 2 × 10−3 bit error rate (BER for 32 quadrature amplitude modulation (QAM with a system baud rate of 500 MHz. The wide bandwidth and high gain along with the excellent performance of the proposed 4 × 4 antenna array unit cell makes it an excellent candidate for future 5G wireless communication applications.

  20. Attenuated total internal reflection infrared microspectroscopic imaging using a large-radius germanium internal reflection element and a linear array detector.

    Science.gov (United States)

    Patterson, Brian M; Havrilla, George J

    2006-11-01

    The number of techniques and instruments available for Fourier transform infrared (FT-IR) microspectroscopic imaging has grown significantly over the past few years. Attenuated total internal reflectance (ATR) FT-IR microspectroscopy reduces sample preparation time and has simplified the analysis of many difficult samples. FT-IR imaging has become a powerful analytical tool using either a focal plane array or a linear array detector, especially when coupled with a chemometric analysis package. The field of view of the ATR-IR microspectroscopic imaging area can be greatly increased from 300 x 300 microm to 2500 x 2500 microm using a larger internal reflection element of 12.5 mm radius instead of the typical 1.5 mm radius. This gives an area increase of 70x before aberrant effects become too great. Parameters evaluated include the change in penetration depth as a function of beam displacement, measurements of the active area, magnification factor, and change in spatial resolution over the imaging area. Drawbacks such as large file size will also be discussed. This technique has been successfully applied to the FT-IR imaging of polydimethylsiloxane foam cross-sections, latent human fingerprints, and a model inorganic mixture, which demonstrates the usefulness of the method for pharmaceuticals.

  1. Advanced statistical tools for SNP arrays : signal calibration, copy number estimation and single array genotyping

    NARCIS (Netherlands)

    Rippe, Ralph Christian Alexander

    2012-01-01

    Fluorescence bias in in signals from individual SNP arrays can be calibrated using linear models. Given the data, the system of equations is very large, so a specialized symbolic algorithm was developed. These models are also used to illustrate that genomic waves do not exist, but are merely an

  2. [Development of a portable mid-infrared rapid analyzer for oil concentration in water based on MEMS linear sensor array].

    Science.gov (United States)

    Gao, Zhi-fan; Zeng, Li-bo; Shi, Lei; Li, Kai; Yang, Yuan-zhou; Wu, Qiong-shui

    2014-06-01

    Aiming at the existing problems such as weak environmental adaptability, low analytic efficiency and poor measuring repeatability in the traditional spectral oil analyzers, the present paper designed a portable mid-infrared rapid analyzer for oil concentration in water. To reduce the volume of the instrument, the non-symmetrical folding M-type Czerny-Turner optical structure was adopted in the core optical path. With a periodically rotating chopper, controlled by digital PID algorithm, applied for infrared light modulation, the modulating accuracy reached ±0.5%. Different from traditional grating-scanning spectrophotometers, this instrument used a fixed grating for light dispersion and avoided rotating error in the course of the measuring procedures. A new-type MEMS infrared linear sensor array was applied for modulated spectral signals detection, which improved the measuring efficiency remarkably. Optical simulation and experimental results indicate that the spectral range is 2 800 - 3 200 cm(-1), the spectral resolution is 6 cm(-1) (@3 130 cm(-1)), and the signal to noise ratio is up to 5 200 : 1. The acquisition time is 13 milliseconds per spectrogram, and the standard deviation of absorbance is less than 3 x 10(-3). These performances meet the standards of oil concentration measurements perfectly. Compared with traditional infrared spectral analyzers for oil concentration, the instrument demonstrated in this paper has many advantages such as smaller size, more efficiency, higher precision, and stronger vibration & moisture isolation. In addition, the proposed instrument is especially suitable for the environmental monitoring departments to implement real-time measurements in the field for oil concentration in water, hence it has broad prospects of application in the field of water quality monitoring.

  3. Modeling and analysis of mover gaps in tubular moving-magnet linear oscillating motors

    Directory of Open Access Journals (Sweden)

    Xuesong LUO

    2018-05-01

    Full Text Available A tubular moving-magnet linear oscillating motor (TMMLOM has merits of high efficiency and excellent dynamic capability. To enhance the thrust performance, quasi-Halbach permanent magnet (PM arrays are arranged on its mover in the application of a linear electro-hydrostatic actuator in more electric aircraft. The arrays are assembled by several individual segments, which lead to gaps between them inevitably. To investigate the effects of the gaps on the radial magnetic flux density and the machine thrust in this paper, an analytical model is built considering both axial and radial gaps. The model is validated by finite element simulations and experimental results. Distributions of the magnetic flux are described in condition of different sizes of radial and axial gaps. Besides, the output force is also discussed in normal and end windings. Finally, the model has demonstrated that both kinds of gaps have a negative effect on the thrust, and the linear motor is more sensitive to radial ones. Keywords: Air-gap flux density, Linear motor, Mover gaps, Quasi-Halbach array, Thrust output, Tubular moving-magnet linear oscillating motor (TMMLOM

  4. LED Uniform Illumination Using Double Linear Fresnel Lenses for Energy Saving

    Directory of Open Access Journals (Sweden)

    Ngoc Hai Vu

    2017-12-01

    Full Text Available We present a linear Fresnel lens design for light-emitting diode (LED uniform illumination applications. The LED source is an array of LEDs. An array of collimating lens is applied to collimate output from the LED array. Two linear Fresnel lenses are used to redistribute the collimated beam along two dimensions in the illumination area. Collimating lens and linear Fresnel lens surfaces are calculated by geometrical optics and nonimaging optics. The collimated beam output from the collimating lens array is divided into many fragments. Each fragment is refracted by a segment of Fresnel lens and distributed over the illumination area, so that the total beam can be distributed to the illumination target uniformly. The simulation results show that this design has a compact structure, high optical efficiency of 82% and good uniformity of 76.9%. Some consideration of the energy savings and optical performance are discussed by comparison with other typical light sources. The results show that our proposed LED lighting system can reduce energy consumption five-times in comparison to using a conventional fluorescent lamp. Our research is a strong candidate for low cost, energy savings for indoor and outdoor lighting applications.

  5. 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

  6. Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties.

    Science.gov (United States)

    Cupo, Andrew; Masih Das, Paul; Chien, Chen-Chi; Danda, Gopinath; Kharche, Neerav; Tristant, Damien; Drndić, Marija; Meunier, Vincent

    2017-07-25

    A tunable band gap in phosphorene extends its applicability in nanoelectronic and optoelectronic applications. Here, we propose to tune the band gap in phosphorene by patterning antidot lattices, which are periodic arrays of holes or nanopores etched in the material, and by exploiting quantum confinement in the corresponding nanoconstrictions. We fabricated antidot lattices with radii down to 13 nm in few-layer black phosphorus flakes protected by an oxide layer and observed suppression of the in-plane phonon modes relative to the unmodified material via Raman spectroscopy. In contrast to graphene antidots, the Raman peak positions in few-layer BP antidots are unchanged, in agreement with predicted power spectra. We also use DFT calculations to predict the electronic properties of phosphorene antidot lattices and observe a band gap scaling consistent with quantum confinement effects. Deviations are attributed primarily to self-passivating edge morphologies, where each phosphorus atom has the same number of bonds per atom as the pristine material so that no dopants can saturate dangling bonds. Quantum confinement is stronger for the zigzag edge nanoconstrictions between the holes as compared to those with armchair edges, resulting in a roughly bimodal band gap distribution. Interestingly, in two of the antidot structures an unreported self-passivating reconstruction of the zigzag edge endows the systems with a metallic component. The experimental demonstration of antidots and the theoretical results provide motivation to further scale down nanofabrication of antidots in the few-nanometer size regime, where quantum confinement is particularly important.

  7. Electronic correlations and disorder in transport through one-dimensional nanoparticle arrays

    OpenAIRE

    Bascones, E.; Estevez, V.; Trinidad, J. A.; MacDonald, A. H.

    2007-01-01

    We analyze and clarify the transport properties of a one-dimensional metallic nanoparticle array with interaction between charges restricted to charges placed in the same conductor. We study the threshold voltage, the I-V curves and the potential drop through the array and their dependence on the array parameters including the effect of charge and resistance disorder. We show that very close to threshold the current depends linearly on voltage with a slope independent on the array size. At in...

  8. 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.

  9. Parallel algorithms for numerical linear algebra

    CERN Document Server

    van der Vorst, H

    1990-01-01

    This is the first in a new series of books presenting research results and developments concerning the theory and applications of parallel computers, including vector, pipeline, array, fifth/future generation computers, and neural computers.All aspects of high-speed computing fall within the scope of the series, e.g. algorithm design, applications, software engineering, networking, taxonomy, models and architectural trends, performance, peripheral devices.Papers in Volume One cover the main streams of parallel linear algebra: systolic array algorithms, message-passing systems, algorithms for p

  10. Resonance spectra of diabolo optical antenna arrays

    Directory of Open Access Journals (Sweden)

    Hong Guo

    2015-10-01

    Full Text Available A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  11. EMG-Torque Relation in Chronic Stroke: A Novel EMG Complexity Representation With a Linear Electrode Array.

    Science.gov (United States)

    Zhang, Xu; Wang, Dongqing; Yu, Zaiyang; Chen, Xiang; Li, Sheng; Zhou, Ping

    2017-11-01

    This study examines the electromyogram (EMG)-torque relation for chronic stroke survivors using a novel EMG complexity representation. Ten stroke subjects performed a series of submaximal isometric elbow flexion tasks using their affected and contralateral arms, respectively, while a 20-channel linear electrode array was used to record surface EMG from the biceps brachii muscles. The sample entropy (SampEn) of surface EMG signals was calculated with both global and local tolerance schemes. A regression analysis was performed between SampEn of each channel's surface EMG and elbow flexion torque. It was found that a linear regression can be used to well describe the relation between surface EMG SampEn and the torque. Each channel's root mean square (RMS) amplitude of surface EMG signal in the different torque level was computed to determine the channel with the highest EMG amplitude. The slope of the regression (observed from the channel with the highest EMG amplitude) was smaller on the impaired side than on the nonimpaired side in 8 of the 10 subjects, regardless of the tolerance scheme (global or local) and the range of torques (full or matched range) used for comparison. The surface EMG signals from the channels above the estimated muscle innervation zones demonstrated significantly lower levels of complexity compared with other channels between innervation zones and muscle tendons. The study provides a novel point of view of the EMG-torque relation in the complexity domain, and reveals its alterations post stroke, which are associated with complex neural and muscular changes post stroke. The slope difference between channels with regard to innervation zones also confirms the relevance of electrode position in surface EMG analysis.

  12. Coherent transport in a system of periodic linear chain of quantum dots situated between two parallel quantum wires

    International Nuclear Information System (INIS)

    Petrosyan, Lyudvig S

    2016-01-01

    We study coherent transport in a system of periodic linear chain of quantum dots situated between two parallel quantum wires. We show that the resonant-tunneling conductance between the wires exhibits a Rabi splitting of the resonance peak as a function of Fermi energy in the wires. This effect is an electron transport analogue of the Rabi splitting in optical spectra of two interacting systems. The conductance peak splitting originates from the anticrossing of Bloch bands in a periodic system that is caused by a strong coupling between the electron states in the quantum dot chain and quantum wires. (paper)

  13. Geometric Potential Assessment for ZY3-02 Triple Linear Array Imagery

    Directory of Open Access Journals (Sweden)

    Kai Xu

    2017-06-01

    Full Text Available ZiYuan3-02 (ZY3-02 is the first remote sensing satellite for the development of China’s civil space infrastructure (CCSI and the second satellite in the ZiYuan3 series; it was launched successfully on 30 May 2016, aboard the CZ-4B rocket at the Taiyuan Satellite Launch Center (TSLC in China. Core payloads of ZY3-02 include a triple linear array camera (TLC and a multi-spectral camera, and this equipment will be used to acquire space geographic information with high-resolution and stereoscopic observations. Geometric quality is a key factor that affects the performance and potential of satellite imagery. For the purpose of evaluating comprehensively the geometric potential of ZY3-02, this paper introduces the method used for geometric calibration of the TLC onboard the satellite and a model for sensor corrected (SC products that serve as basic products delivered to users. Evaluation work was conducted by making a full assessment of the geometric performance. Furthermore, images of six regions and corresponding reference data were collected to implement the geometric calibration technique and evaluate the resulting geometric accuracy. Experimental results showed that the direct location performance and internal accuracy of SC products increased remarkably after calibration, and the planimetric and vertical accuracies with relatively few ground control points (GCPs were demonstrated to be better than 2.5 m and 2 m, respectively. Additionally, the derived digital surface model (DSM accuracy was better than 3 m (RMSE for flat terrain and 5 m (RMSE for mountainous terrain. However, given that several variations such as changes in the thermal environment can alter the camera’s installation angle, geometric performance will vary with the geographical location and imaging time changes. Generally, ZY3-02 can be used for 1:50,000 stereo mapping and can produce (and update larger-scale basic geographic information products.

  14. Multi-Beam Radio Frequency (RF) Aperture Arrays Using Multiplierless Approximate Fast Fourier Transform (FFT)

    Science.gov (United States)

    2017-08-01

    Fourier transform, discrete Fourier transform, digital array processing , antenna beamformers 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...125 3.7 Simulation of 2-D Beams Cross Sections .................................................................... 125 3.7.1 8...unlimited. List of Figures Figure Page Figure 1: N-beam Array Processing System using a Linear Array

  15. MLAOS: A Multi-Point Linear Array of Optical Sensors for Coniferous Foliage Clumping Index Measurement

    Directory of Open Access Journals (Sweden)

    Yonghua Qu

    2014-05-01

    Full Text Available The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS, which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8–10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy.

  16. Modulational Instability in Linearly Coupled Asymmetric Dual-Core Fibers

    Directory of Open Access Journals (Sweden)

    Arjunan Govindarajan

    2017-06-01

    Full Text Available We investigate modulational instability (MI in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from the linearization with respect to small perturbations. First, we compare the MI spectra of the asymmetric system and its symmetric counterpart in the case of the anomalous group-velocity dispersion (GVD. In particular, it is demonstrated that the increase of the inter-core linear-coupling coefficient leads to a reduction of the MI gain spectrum in the asymmetric coupler. The analysis is extended for the asymmetric system in the normal-GVD regime, where the coupling induces and controls the MI, as well as for the system with opposite GVD signs in the two cores. Following the analytical consideration of the MI, numerical simulations are carried out to explore nonlinear development of the MI, revealing the generation of periodic chains of localized peaks with growing amplitudes, which may transform into arrays of solitons.

  17. Dendroclimatic transfer functions revisited: Little Ice Age and Medieval Warm Period summer temperatures reconstructed using artificial neural networks and linear algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Helama, S.; Holopainen, J.; Eronen, M. [Department of Geology, University of Helsinki, (Finland); Makarenko, N.G. [Russian Academy of Sciences, St. Petersburg (Russian Federation). Pulkovo Astronomical Observatory; Karimova, L.M.; Kruglun, O.A. [Institute of Mathematics, Almaty (Kazakhstan); Timonen, M. [Finnish Forest Research Institute, Rovaniemi Research Unit (Finland); Merilaeinen, J. [SAIMA Unit of the Savonlinna Department of Teacher Education, University of Joensuu (Finland)

    2009-07-01

    Tree-rings tell of past climates. To do so, tree-ring chronologies comprising numerous climate-sensitive living-tree and subfossil time-series need to be 'transferred' into palaeoclimate estimates using transfer functions. The purpose of this study is to compare different types of transfer functions, especially linear and nonlinear algorithms. Accordingly, multiple linear regression (MLR), linear scaling (LSC) and artificial neural networks (ANN, nonlinear algorithm) were compared. Transfer functions were built using a regional tree-ring chronology and instrumental temperature observations from Lapland (northern Finland and Sweden). In addition, conventional MLR was compared with a hybrid model whereby climate was reconstructed separately for short- and long-period timescales prior to combining the bands of timescales into a single hybrid model. The fidelity of the different reconstructions was validated against instrumental climate data. The reconstructions by MLR and ANN showed reliable reconstruction capabilities over the instrumental period (AD 1802-1998). LCS failed to reach reasonable verification statistics and did not qualify as a reliable reconstruction: this was due mainly to exaggeration of the low-frequency climatic variance. Over this instrumental period, the reconstructed low-frequency amplitudes of climate variability were rather similar by MLR and ANN. Notably greater differences between the models were found over the actual reconstruction period (AD 802-1801). A marked temperature decline, as reconstructed by MLR, from the Medieval Warm Period (AD 931-1180) to the Little Ice Age (AD 1601-1850), was evident in all the models. This decline was approx. 0.5 C as reconstructed by MLR. Different ANN based palaeotemperatures showed simultaneous cooling of 0.2 to 0.5 C, depending on algorithm. The hybrid MLR did not seem to provide further benefit above conventional MLR in our sample. The robustness of the conventional MLR over the calibration

  18. Study on data acquisition circuit used in SSPA linear array detector X-ray detection

    CERN Document Server

    Wei Biao; Che Zhen Ping

    2002-01-01

    After SSPA used as X-ray array detector is developed, the authors take a research on the data acquisition circuit applied to the detector. The experiment designed has verified the feasibility of application of this array detector and its data acquisition circuit to X-ray computed tomography (X-CT). The preliminary test results indicate that the method of the X-ray detection is feasible for industry X-CT nondestructive testing, which brings about advantage for detecting and measuring with high resolution, good efficiency and low cost

  19. Wireless Sensor Array Network DoA Estimation from Compressed Array Data via Joint Sparse Representation.

    Science.gov (United States)

    Yu, Kai; Yin, Ming; Luo, Ji-An; Wang, Yingguan; Bao, Ming; Hu, Yu-Hen; Wang, Zhi

    2016-05-23

    A compressive sensing joint sparse representation direction of arrival estimation (CSJSR-DoA) approach is proposed for wireless sensor array networks (WSAN). By exploiting the joint spatial and spectral correlations of acoustic sensor array data, the CSJSR-DoA approach provides reliable DoA estimation using randomly-sampled acoustic sensor data. Since random sampling is performed at remote sensor arrays, less data need to be transmitted over lossy wireless channels to the fusion center (FC), and the expensive source coding operation at sensor nodes can be avoided. To investigate the spatial sparsity, an upper bound of the coherence of incoming sensor signals is derived assuming a linear sensor array configuration. This bound provides a theoretical constraint on the angular separation of acoustic sources to ensure the spatial sparsity of the received acoustic sensor array signals. The Cram e ´ r-Rao bound of the CSJSR-DoA estimator that quantifies the theoretical DoA estimation performance is also derived. The potential performance of the CSJSR-DoA approach is validated using both simulations and field experiments on a prototype WSAN platform. Compared to existing compressive sensing-based DoA estimation methods, the CSJSR-DoA approach shows significant performance improvement.

  20. Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

    Science.gov (United States)

    Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

    2016-03-01

    The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

  1. Control Strategies for Arrays of Wave Energy Devices

    OpenAIRE

    Westphalen, J; Bacelli, G; Balitsky, P; Ringwood, John

    2011-01-01

    In this paper, we investigate the differences between two control strategies for a two-device linear array of wave energy converters (WEC) for device spacings of 4 to 80 times the device diameter. The WECs operate in heave only and are controlled in real time. The control strategies, called the independent device and global array control, estimate the excitation forces and calculate the optimum vertical velocity trajectory and reactive power take off force to achieve the ...

  2. Performance Analysis of Digital loudspeaker Arrays

    DEFF Research Database (Denmark)

    Pedersen, Bo Rohde; Kontomichos, Fotios; Mourjopoulos, John

    2008-01-01

    An analysis of digital loudspeaker arrays shows that the ways in which bits are mapped to the drivers influence the quality of the audio result. Specifically, a "bit-summed" rather than the traditional "bit-mapped" strategy greatly reduces the number of times drivers make binary transitions per...... period of the input frequency. Detailed simulations compare the results for a 32-loudspeaker array with a similar configuration with analog excitation of the drivers. Ideally, drivers in digital arrays should be very small and span a small area, but that sets limits on the low-frequency response...

  3. Output-only modal analysis of linear time-periodic systems with application to wind turbine simulation data

    DEFF Research Database (Denmark)

    Allen, Matthew S.; Sracic, Michael W.; Chauhan, Shashank

    2011-01-01

    to interrogate simulated measurements from a rotating wind turbine. The measurements were simulated for a 5 MW turbine modeled in the HAWC2 simulation code, which includes both structural dynamic and aerodynamic effects. This simulated system identification provides insights into the test and measurement......Many important systems, such as wind turbines, helicopters and turbomachinery, must be modeled with linear time-periodic equations of motion to correctly predict resonance phenomena. Time periodic effects in wind turbines might arise due to blade-to-blade manufacturing variations, stratification...... in the velocity of the wind with height and changes in the aerodynamics of the blades as they pass the tower. These effects may cause parametric resonance or other unexpected phenomena, so it is important to properly characterize them so that these machines can be designed to achieve high reliability, safety...

  4. 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

  5. Solving “Antenna Array Thinning Problem” Using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Rajashree Jain

    2012-01-01

    Full Text Available Thinning involves reducing total number of active elements in an antenna array without causing major degradation in system performance. Dynamic thinning is the process of achieving this under real-time conditions. It is required to find a strategic subset of antenna elements for thinning so as to have its optimum performance. From a mathematical perspective this is a nonlinear, multidimensional problem with multiple objectives and many constraints. Solution for such problem cannot be obtained by classical analytical techniques. It will be required to employ some type of search algorithm which can lead to a practical solution in an optimal. The present paper discusses an approach of using genetic algorithm for array thinning. After discussing the basic concept involving antenna array, array thinning, dynamic thinning, and application methodology, simulation results of applying the technique to linear and planar arrays are presented.

  6. Self-assembled biomimetic superhydrophobic hierarchical arrays.

    Science.gov (United States)

    Yang, Hongta; Dou, Xuan; Fang, Yin; Jiang, Peng

    2013-09-01

    Here, we report a simple and inexpensive bottom-up technology for fabricating superhydrophobic coatings with hierarchical micro-/nano-structures, which are inspired by the binary periodic structure found on the superhydrophobic compound eyes of some insects (e.g., mosquitoes and moths). Binary colloidal arrays consisting of exemplary large (4 and 30 μm) and small (300 nm) silica spheres are first assembled by a scalable Langmuir-Blodgett (LB) technology in a layer-by-layer manner. After surface modification with fluorosilanes, the self-assembled hierarchical particle arrays become superhydrophobic with an apparent water contact angle (CA) larger than 150°. The throughput of the resulting superhydrophobic coatings with hierarchical structures can be significantly improved by templating the binary periodic structures of the LB-assembled colloidal arrays into UV-curable fluoropolymers by a soft lithography approach. Superhydrophobic perfluoroether acrylate hierarchical arrays with large CAs and small CA hysteresis can be faithfully replicated onto various substrates. Both experiments and theoretical calculations based on the Cassie's dewetting model demonstrate the importance of the hierarchical structure in achieving the final superhydrophobic surface states. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

    International Nuclear Information System (INIS)

    Bloomfield, P.

    1992-01-01

    The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end

  8. 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.

  9. Theory and applications of spherical microphone array processing

    CERN Document Server

    Jarrett, Daniel P; Naylor, Patrick A

    2017-01-01

    This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to ...

  10. Direction-of-Arrival Estimation with Coarray ESPRIT for Coprime Array.

    Science.gov (United States)

    Zhou, Chengwei; Zhou, Jinfang

    2017-08-03

    A coprime array is capable of achieving more degrees-of-freedom for direction-of-arrival (DOA) estimation than a uniform linear array when utilizing the same number of sensors. However, existing algorithms exploiting coprime array usually adopt predefined spatial sampling grids for optimization problem design or include spectrum peak search process for DOA estimation, resulting in the contradiction between estimation performance and computational complexity. To address this problem, we introduce the Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) to the coprime coarray domain, and propose a novel coarray ESPRIT-based DOA estimation algorithm to efficiently retrieve the off-grid DOAs. Specifically, the coprime coarray statistics are derived according to the received signals from a coprime array to ensure the degrees-of-freedom (DOF) superiority, where a pair of shift invariant uniform linear subarrays is extracted. The rotational invariance of the signal subspaces corresponding to the underlying subarrays is then investigated based on the coprime coarray covariance matrix, and the incorporation of ESPRIT in the coarray domain makes it feasible to formulate the closed-form solution for DOA estimation. Theoretical analyses and simulation results verify the efficiency and the effectiveness of the proposed DOA estimation algorithm.

  11. Fabrication and mechanical properties of anodized zirconium dioxide nanotubular arrays

    International Nuclear Information System (INIS)

    Wang Luning; Luo Jingli

    2011-01-01

    A series of highly ordered ZrO 2 nanotubular arrays with different thickness was synthesized by changing the anodization voltage or anodization period. The thickness of the nanotubular arrays depended on the anodization voltage and anodization period. Openings of the tubular structure were only slightly affected by the anodization voltage. Microindentation tests demonstrated that the apparent Young's modulus, ratio of elastic energy to the total deformation energy and hardness decreased as the thickness of the nanotubular array films increased due to densification and collapse of longer nanotubes under external force. Resistance of nanotubular arrays to sliding wear was evaluated in different cultures. Wear loss, which was proportional to the width of the wear track, significantly decreased in water compared with that in air. The pH values of solutions slightly affected the width of the wear track of the ZrO 2 nanotubular arrays. The results showed that wear loss of the ZrO 2 nanotubular arrays and friction force on the ZrO 2 nanotubular arrays decreased with increasing pH from 2.5 to 13.

  12. A high-order perturbation of surfaces method for scattering of linear waves by periodic multiply layered gratings in two and three dimensions

    Science.gov (United States)

    Hong, Youngjoon; Nicholls, David P.

    2017-09-01

    The capability to rapidly and robustly simulate the scattering of linear waves by periodic, multiply layered media in two and three dimensions is crucial in many engineering applications. In this regard, we present a High-Order Perturbation of Surfaces method for linear wave scattering in a multiply layered periodic medium to find an accurate numerical solution of the governing Helmholtz equations. For this we truncate the bi-infinite computational domain to a finite one with artificial boundaries, above and below the structure, and enforce transparent boundary conditions there via Dirichlet-Neumann Operators. This is followed by a Transformed Field Expansion resulting in a Fourier collocation, Legendre-Galerkin, Taylor series method for solving the problem in a transformed set of coordinates. Assorted numerical simulations display the spectral convergence of the proposed algorithm.

  13. Refracting surface plasmon polaritons with nanoparticle arrays

    DEFF Research Database (Denmark)

    Radko, I.P.; Evlyukhin, A.B.; Boltasseva, Alexandra

    2008-01-01

    Refraction of surface plasmon polaritons (SPPs) by various structures formed by a 100-nm-period square lattice of gold nanoparticles on top of a gold film is studied by leakage radiation microscopy. SPP refraction by a triangular-shaped nanoparticle array indicates that the SPP effective refractive...... to design nanoparticle arrays for specific applications requiring in-plane SPP manipulation....

  14. Periodic Application of Concurrent Error Detection in Processor Array Architectures. PhD. Thesis -

    Science.gov (United States)

    Chen, Paul Peichuan

    1993-01-01

    Processor arrays can provide an attractive architecture for some applications. Featuring modularity, regular interconnection and high parallelism, such arrays are well-suited for VLSI/WSI implementations, and applications with high computational requirements, such as real-time signal processing. Preserving the integrity of results can be of paramount importance for certain applications. In these cases, fault tolerance should be used to ensure reliable delivery of a system's service. One aspect of fault tolerance is the detection of errors caused by faults. Concurrent error detection (CED) techniques offer the advantage that transient and intermittent faults may be detected with greater probability than with off-line diagnostic tests. Applying time-redundant CED techniques can reduce hardware redundancy costs. However, most time-redundant CED techniques degrade a system's performance.

  15. Dynamics of unsymmetric piecewise-linear/non-linear systems using finite elements in time

    Science.gov (United States)

    Wang, Yu

    1995-08-01

    The dynamic response and stability of a single-degree-of-freedom system with unsymmetric piecewise-linear/non-linear stiffness are analyzed using the finite element method in the time domain. Based on a Hamilton's weak principle, this method provides a simple and efficient approach for predicting all possible fundamental and sub-periodic responses. The stability of the steady state response is determined by using Floquet's theory without any special effort for calculating transition matrices. This method is applied to a number of examples, demonstrating its effectiveness even for a strongly non-linear problem involving both clearance and continuous stiffness non-linearities. Close agreement is found between available published findings and the predictions of the finite element in time approach, which appears to be an efficient and reliable alternative technique for non-linear dynamic response and stability analysis of periodic systems.

  16. Waferscale Electrostatic Quadrupole Array for Multiple Ion Beam Manipulation

    OpenAIRE

    Vinayakumar, K. B.; Persaud, A.; Seidl, P. A.; Ji, Q.; Waldron, W. L.; Schenkel, T.; Ardanuc, S.; Lal, A.

    2018-01-01

    We report on the first through-wafer silicon-based Electrostatic Quadrupole Array (ESQA) to focus high energy ion beams. This device is a key enabler for a wafer based accelerator architecture that lends itself to orders-of-magnitude reduction in cost, volume and weight of charged particle accelerators. ESQs are a key building block in developing compact Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) [1]. In a MEQALAC electrostatic forces are used to focus ions, and elec...

  17. Enhanced THz extinction in arrays of resonant semiconductor particles

    NARCIS (Netherlands)

    Schaafsma, M. C.; Georgiou, G.; J. Gomez Rivas,

    2015-01-01

    We demonstrate experimentally the enhanced THz extinction by periodic arrays of resonant semiconductor particles. This phenomenon is explained in terms of the radiative coupling of localized resonances with diffractive orders in the plane of the array (Rayleigh anomalies). The experimental results

  18. 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.

  19. Effects of linear and nonlinear time-delayed feedback on the noise-enhanced stability phenomenon in a periodically driven bistable system

    International Nuclear Information System (INIS)

    Jia, Zheng-Lin; Mei, Dong-Cheng

    2011-01-01

    We investigate numerically the effects of time delay on the phenomenon of noise-enhanced stability (NES) in a periodically modulated bistable system. Three types of time-delayed feedback, including linear delayed feedback, nonlinear delayed feedback and global delayed feedback, are considered. We find a non-monotonic behaviour of the mean first-passage time (MFPT) as a function of the delay time τ, with a maximum in the case of linear delayed feedback and with a minimum in the case of nonlinear delayed feedback. There are two peculiar values of τ around which the NES phenomenon is enhanced or weakened. For the case of global delayed feedback, the increase of τ always weakens the NES phenomenon. Moreover, we also show that the amplitude A and the frequency Ω of the periodic forcing play an opposite role in the NES phenomenon, i.e. the increase of A weakens the NES effect while the increase of Ω enhances it. These observations demonstrate that the time-delayed feedback can be used as a feasible control scheme for the NES phenomenon

  20. Vortex lattice matching effects in a washboard pinning potential induced by Co nanostripe arrays

    International Nuclear Information System (INIS)

    Dobrovolskiy, Oleksandr V.; Begun, Evgeniya; Huth, Michael; Shklovskij, Valerij A.; Tsindlekht, Menachem I.

    2011-01-01

    We furnish superconducting Nb thin films with linearly-extended uniaxial pinning nanostructures. An array of Co stripes is deposited by focused electron beam-induced deposition. Nanostructures are designed to be commensurate with the vortex lattice at small magnetic fields. We investigate vortex lattice matching effects by magneto-transport measurements. Drops in ρ(B) are observed only when the vortex lattice parameter matches the nanostructure period. No matching effects corresponding to the Co stripe width have been observed. Drops in ρ(B) are more pronounced for the vortex motion perpendicular to the Co stripes. An advanced mask-less nanofabrication technique, focused electron beam-induced deposition (FEBID), has been employed on epitaxial Nb thin films to prepare ferromagnetic decorations in the form of an array of Co stripes. These substantially modify the non-patterned films' superconducting properties, providing a washboard-like pinning potential landscape for the vortex motion. At small magnetic fields B ≤ 0.1 T, vortex lattice matching effects have been investigated by magneto-transport measurements. Step-like drops in the field dependencies of the films resistivity ρ(B) have been observed in particular for the vortex motion perpendicular to the Co stripes. The field values, corresponding to the middle points of these drops in ρ(B), meet the vortex lattice parameter matching the pinning structure's period. These disagree with the results of Jaque et al. (2002) , who observed matching effects corresponding to the stripe width in Nb films grown on periodically distributed submicrometric lines of Ni.

  1. Solitary waves under the competition of linear and nonlinear periodic potentials

    International Nuclear Information System (INIS)

    Rapti, Z; Kevrekidis, P G; Konotop, V V; Jones, C K R T

    2007-01-01

    In this paper, we study the competition of the linear and nonlinear lattices and its effects on the stability and dynamics of bright solitary waves. We consider both lattices in a perturbative framework, whereby the technique of Hamiltonian perturbation theory can be used to obtain information about the existence of solutions, and the same approach, as well as eigenvalue count considerations, can be used to obtain detailed conditions about their linear stability. We find that the analytical results are in very good agreement with our numerical findings and can also be used to predict features of the dynamical evolution of such solutions. A particularly interesting result of these considerations is the existence of a tunable cancellation effect between the linear and nonlinear lattices that allows for increased mobility of the solitary wave

  2. The data array, a tool to interface the user to a large data base

    Science.gov (United States)

    Foster, G. H.

    1974-01-01

    Aspects of the processing of spacecraft data is considered. Use of the data array in a large address space as an intermediate form in data processing for a large scientific data base is advocated. Techniques for efficient indexing in data arrays are reviewed and the data array method for mapping an arbitrary structure onto linear address space is shown. A compromise between the two forms is given. The impact of the data array on the user interface are considered along with implementation.

  3. Ring-array processor distribution topology for optical interconnects

    Science.gov (United States)

    Li, Yao; Ha, Berlin; Wang, Ting; Wang, Sunyu; Katz, A.; Lu, X. J.; Kanterakis, E.

    1992-01-01

    The existing linear and rectangular processor distribution topologies for optical interconnects, although promising in many respects, cannot solve problems such as clock skews, the lack of supporting elements for efficient optical implementation, etc. The use of a ring-array processor distribution topology, however, can overcome these problems. Here, a study of the ring-array topology is conducted with an aim of implementing various fast clock rate, high-performance, compact optical networks for digital electronic multiprocessor computers. Practical design issues are addressed. Some proof-of-principle experimental results are included.

  4. 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...

  5. Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

    Directory of Open Access Journals (Sweden)

    Zhou Lin

    2016-03-01

    Full Text Available The linear-transformer-driver (LTD is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z-pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z-pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%–90% can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32  cm/μs when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%–30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

  6. Limited Diffraction Maps for Pulsed Wave Annular Arrays

    DEFF Research Database (Denmark)

    Fox, Paul D.

    2002-01-01

    A procedure is provided for decomposing the linear field of flat pulsed wave annular arrays into an equivalent set of known limited diffraction Bessel beams. Each Bessel beam propagates with known characteristics, enabling good insight into the propagation of annular fields to be obtained...

  7. Linear and nonlinear susceptibilities from diffusion quantum Monte Carlo: application to periodic hydrogen chains.

    Science.gov (United States)

    Umari, P; Marzari, Nicola

    2009-09-07

    We calculate the linear and nonlinear susceptibilities of periodic longitudinal chains of hydrogen dimers with different bond-length alternations using a diffusion quantum Monte Carlo approach. These quantities are derived from the changes in electronic polarization as a function of applied finite electric field--an approach we recently introduced and made possible by the use of a Berry-phase, many-body electric-enthalpy functional. Calculated susceptibilities and hypersusceptibilities are found to be in excellent agreement with the best estimates available from quantum chemistry--usually extrapolations to the infinite-chain limit of calculations for chains of finite length. It is found that while exchange effects dominate the proper description of the susceptibilities, second hypersusceptibilities are greatly affected by electronic correlations. We also assess how different approximations to the nodal surface of the many-body wave function affect the accuracy of the calculated susceptibilities.

  8. 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...

  9. Angular spectrum approach for fast simulation of pulsed non-linear ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2011-01-01

    The paper presents an Angular Spectrum Approach (ASA) for simulating pulsed non-linear ultrasound fields. The source of the ASA is generated by Field II, which can simulate array transducers of any arbitrary geometry and focusing. The non-linear ultrasound simulation program - Abersim, is used...... as the reference. A linear array transducer with 64 active elements is simulated by both Field II and Abersim. The excitation is a 2-cycle sine wave with a frequency of 5 MHz. The second harmonic field in the time domain is simulated using ASA. Pulse inversion is used in the Abersim simulation to remove...... the fundamental and keep the second harmonic field, since Abersim simulates non-linear fields with all harmonic components. ASA and Abersim are compared for the pulsed fundamental and second harmonic fields in the time domain at depths of 30 mm, 40 mm (focal depth) and 60 mm. Full widths at -6 dB (FWHM) are f0...

  10. An MLC calibration method using a detector array

    International Nuclear Information System (INIS)

    Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray

    2009-01-01

    Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 ±0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of ±0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

  11. An MLC calibration method using a detector array

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray [Department of Nuclear and Radiological Engineering, University of Florida, 202 Nuclear Science Building, Gainesville, Florida 32611-8300 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States) and Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States); Department of Radiation Oncology, Tulane University, 1415 Tulane Ave, HC65, New Orleans, Louisiana 70112 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

    2009-10-15

    Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 {+-}0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of {+-}0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

  12. Chaos and loss of predictability in the periodically kicked linear oscillator

    International Nuclear Information System (INIS)

    Luna-Acosta, G.A.; Cantoral, E.

    1989-01-01

    Chernikov et.al. [2] have discovered new features in the dynamics of a periodically kicked LHO x'' + ω 0 2 x = ( K/ k 0 T 2 ) sin (k 0 x) x Σ n δ (t / T - n). They report that its phase space motion under exact resonance (p ω 0 = (2 π / T) q; p, q integers), and with initial conditions on the separatrix of the average Hamiltonian , accelerates unboundedly along a fractal stochastic web with q-fold symmetry. Here we investigate with numerical experiments the effects of small deviations from exact resonance on the diffusion and symmetry patterns. We show graphically that the stochastic webs are (topologically) unstable and thus the unbounded motion becomes considerably truncated. Moreover, we analyze numerically and analytically a simpler (integrable) version. We give its exact closed-form solution in complex numbers, realize that it accelerates unboundedly only when ω 0 = (2 π/T) q (q = ± 1,2,...), and show that for small uncertainties in these frequencies, total predictability is lost as time evolves. That is, trajectories of a set of systems, initially described by close neighboring points in phase space strongly diverge in a non-linear way. The great loss of predictability in the integrable model is due to the combination of translational and rotational symmetries, inherent in these systems. (Author)

  13. Chaos and loss of predictability in the periodically kicked linear oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Luna-Acosta, G A [Universidad Autonoma de Puebla (Mexico). Inst. de Ciencias; Cantoral, E [Universidad Autonoma de Puebla (Mexico). Escuela de Fisica

    1989-01-01

    Chernikov et.al. [2] have discovered new features in the dynamics of a periodically kicked LHO x'' + [omega] [sub 0] [sup 2] x = ( K/ k[sub 0] T [sup 2]) sin (k[sub 0] x) x [Sigma][sub n] [delta] (t / T - n). They report that its phase space motion under exact resonance (p [omega] [sub 0] = (2 [pi] / T) q; p, q integers), and with initial conditions on the separatrix of the average Hamiltonian , accelerates unboundedly along a fractal stochastic web with q-fold symmetry. Here we investigate with numerical experiments the effects of small deviations from exact resonance on the diffusion and symmetry patterns. We show graphically that the stochastic webs are (topologically) unstable and thus the unbounded motion becomes considerably truncated. Moreover, we analyze numerically and analytically a simpler (integrable) version. We give its exact closed-form solution in complex numbers, realize that it accelerates unboundedly only when [omega][sub 0] = (2 [pi]/T) q (q = [+-] 1,2,...), and show that for small uncertainties in these frequencies, total predictability is lost as time evolves. That is, trajectories of a set of systems, initially described by close neighboring points in phase space strongly diverge in a non-linear way. The great loss of predictability in the integrable model is due to the combination of translational and rotational symmetries, inherent in these systems. (Author).

  14. Fault Analysis in Solar Photovoltaic Arrays

    Science.gov (United States)

    Zhao, Ye

    Fault analysis in solar photovoltaic (PV) arrays is a fundamental task to increase reliability, efficiency and safety in PV systems. Conventional fault protection methods usually add fuses or circuit breakers in series with PV components. But these protection devices are only able to clear faults and isolate faulty circuits if they carry a large fault current. However, this research shows that faults in PV arrays may not be cleared by fuses under some fault scenarios, due to the current-limiting nature and non-linear output characteristics of PV arrays. First, this thesis introduces new simulation and analytic models that are suitable for fault analysis in PV arrays. Based on the simulation environment, this thesis studies a variety of typical faults in PV arrays, such as ground faults, line-line faults, and mismatch faults. The effect of a maximum power point tracker on fault current is discussed and shown to, at times, prevent the fault current protection devices to trip. A small-scale experimental PV benchmark system has been developed in Northeastern University to further validate the simulation conclusions. Additionally, this thesis examines two types of unique faults found in a PV array that have not been studied in the literature. One is a fault that occurs under low irradiance condition. The other is a fault evolution in a PV array during night-to-day transition. Our simulation and experimental results show that overcurrent protection devices are unable to clear the fault under "low irradiance" and "night-to-day transition". However, the overcurrent protection devices may work properly when the same PV fault occurs in daylight. As a result, a fault under "low irradiance" and "night-to-day transition" might be hidden in the PV array and become a potential hazard for system efficiency and reliability.

  15. Ferromagnetic resonance response of electron-beam patterned arrays of ferromagnetic nanoparticles

    Science.gov (United States)

    Jung, Sukkoo; Watkins, Byron; Feller, Jeffrey; Ketterson, John; Chandrasekhar, Venkat

    2001-03-01

    We report on the fabrication and the dynamic magnetic properties of periodic permalloy dot arrays. Electron-beam lithography and e-gun evaporation have been used to make the arrays with the aspect ratio of 2 (dot diameter : 40 nm, height : 80 nm) and periods of 100 - 200 nm. The magnetic properties of the arrays and their interactions have been investigated by ferromagnetic resonance (FMR), magnetic force microscopy (MFM), and SQUID magnetometry. The measured FMR data show that the position and magnitude of resonant absorption peaks strongly depend on the angle between magnetic field and the lattice structure. The results of dot arrays with various kinds of structural parameters will be presented. Supported by Army Research Office, DAAD19-99-1-0334/P001

  16. A 2x2 quantum dot array with controllable inter-dot tunnel couplings

    OpenAIRE

    Mukhopadhyay, Uditendu; Dehollain, Juan Pablo; Reichl, Christian; Wegscheider, Werner; Vandersypen, Lieven M. K.

    2018-01-01

    The interaction between electrons in arrays of electrostatically defined quantum dots is naturally described by a Fermi-Hubbard Hamiltonian. Moreover, the high degree of tunability of these systems make them a powerful platform to simulate different regimes of the Hubbard model. However, most quantum dot array implementations have been limited to one-dimensional linear arrays. In this letter, we present a square lattice unit cell of 2$\\times$2 quantum dots defined electrostatically in a AlGaA...

  17. Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring

    Science.gov (United States)

    Su, Yang

    -correlated phase and power measurements from GNSS receivers. Results of horizontal drift velocities and anisotropy ellipses derived from the parameters are shown for several detected events. Results show the possibility of routinely quantifying ionospheric irregularities by drifts and anisotropy. Error analysis on estimated properties is performed to further evaluate the estimation quality. 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. A case study of a single scintillating satellite observed by the array is used to demonstrate the uncertainty estimation process. The distributed array is used in coordination with other measuring techniques such as incoherent scatter radar and optical all-sky imagers. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30-minute period are made and compared to a collocated incoherent scatter radar, and show good agreement in horizontal drift speed and direction during periods of scintillation for cases when the characteristic velocity is less than the drift velocity. The methods demonstrated are extensible to other zones and other GNSS arrays of varying size, number, ground distribution, and transmitter frequency.

  18. Development of a versatile intra-articular pressure sensing array.

    Science.gov (United States)

    Welcher, J B; Popovich, J M; Hedman, T P

    2011-10-01

    A new sensor array intended to accurately and directly measure spatial and time-dependent pressures within a highly curved biological intra-articular joint was developed and tested. To evaluate performance of the new sensor array for application within intra-articular joints generally, and specifically to fit within the relatively restrictive space of the lumbar spine facet joint, geometric constraints of length, width, thickness and sensor spatial resolution were evaluated. Additionally, the effects of sensor array curvature, frequency response, linearity, drift, hysteresis, repeatability, and total system cost were assessed. The new sensor array was approximately 0.6mm in thickness, scalable to below the nominal 12 mm wide by 15 high lumbar spine facet joint size, offered no inherent limitations on the number or spacing of the sensors with less than 1.7% cross talk with sensor immediately adjacent to one another. No difference was observed in sensor performance down to a radius of curvature of 7 mm and a 0.66±0.97% change in sensor sensitivity was observed at a radius of 5.5mm. The sensor array had less than 0.07 dB signal loss up to 5.5 Hz, linearity was 0.58±0.13% full scale (FS), drift was less than 0.2% FS at 250 s and less than 0.6% FS at 700 s, hysteresis was 0.78±0.18%. Repeatability was excellent with a coefficient of variation less than 2% at pressures between 0 and 1.000 MPa. Total system cost was relatively small as standard commercially available data acquisition systems could be utilized, with no specialized software, and individual sensors within an array can be replaced as needed. The new sensor array had small and scalable geometry and very acceptable intrinsic performance including minimal to no alteration in performance at physiologically relevant ranges of joint curvature. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

  19. Determination of flavonoids in plant material by HPLC with diode-array and electro-array detections.

    Science.gov (United States)

    Mattila, P; Astola, J; Kumpulainen, J

    2000-12-01

    A high-performance liquid chromatographic (HPLC) method with in-line connected diode-array (DAD) and electro-array (EC) detection to identify and quantify 17 flavonoids in plant-derived foods is described. Catechins were extracted from the samples using ethyl acetate, and quantification of these compounds was performed with the EC detector. Other flavonoids were quantified with DAD after acid hydrolysis. The methods developed were effective for the determination of catechins and other flavonoids in plant-derived foods. Responses of the detection systems were linear within the range evaluated, 20-200 ng/injection (DAD) and 20-100 ng/injection (EC), with correlation coefficients exceeding 0.999. Coefficient of variation was under 10.5%, and recoveries of flavonoids ranged from 70 to 124%. Purity of the flavonoid peaks was confirmed by combining the spectral and voltammetric data.

  20. 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...

  1. 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)

  2. 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.

  3. High Performance Systolic Array Core Architecture Design for DNA Sequencer

    Directory of Open Access Journals (Sweden)

    Saiful Nurdin Dayana

    2018-01-01

    Full Text Available This paper presents a high performance systolic array (SA core architecture design for Deoxyribonucleic Acid (DNA sequencer. The core implements the affine gap penalty score Smith-Waterman (SW algorithm. This time-consuming local alignment algorithm guarantees optimal alignment between DNA sequences, but it requires quadratic computation time when performed on standard desktop computers. The use of linear SA decreases the time complexity from quadratic to linear. In addition, with the exponential growth of DNA databases, the SA architecture is used to overcome the timing issue. In this work, the SW algorithm has been captured using Verilog Hardware Description Language (HDL and simulated using Xilinx ISIM simulator. The proposed design has been implemented in Xilinx Virtex -6 Field Programmable Gate Array (FPGA and improved in the core area by 90% reduction.

  4. Random-effects linear modeling and sample size tables for two special crossover designs of average bioequivalence studies: the four-period, two-sequence, two-formulation and six-period, three-sequence, three-formulation designs.

    Science.gov (United States)

    Diaz, Francisco J; Berg, Michel J; Krebill, Ron; Welty, Timothy; Gidal, Barry E; Alloway, Rita; Privitera, Michael

    2013-12-01

    Due to concern and debate in the epilepsy medical community and to the current interest of the US Food and Drug Administration (FDA) in revising approaches to the approval of generic drugs, the FDA is currently supporting ongoing bioequivalence studies of antiepileptic drugs, the EQUIGEN studies. During the design of these crossover studies, the researchers could not find commercial or non-commercial statistical software that quickly allowed computation of sample sizes for their designs, particularly software implementing the FDA requirement of using random-effects linear models for the analyses of bioequivalence studies. This article presents tables for sample-size evaluations of average bioequivalence studies based on the two crossover designs used in the EQUIGEN studies: the four-period, two-sequence, two-formulation design, and the six-period, three-sequence, three-formulation design. Sample-size computations assume that random-effects linear models are used in bioequivalence analyses with crossover designs. Random-effects linear models have been traditionally viewed by many pharmacologists and clinical researchers as just mathematical devices to analyze repeated-measures data. In contrast, a modern view of these models attributes an important mathematical role in theoretical formulations in personalized medicine to them, because these models not only have parameters that represent average patients, but also have parameters that represent individual patients. Moreover, the notation and language of random-effects linear models have evolved over the years. Thus, another goal of this article is to provide a presentation of the statistical modeling of data from bioequivalence studies that highlights the modern view of these models, with special emphasis on power analyses and sample-size computations.

  5. Malvar-He-Cutler Linear Image Demosaicking

    Directory of Open Access Journals (Sweden)

    Pascal Getreuer

    2011-08-01

    Full Text Available Image demosaicking (or demosaicing is the interpolation problem of estimating complete color information for an image that has been captured through a color filter array (CFA, particularly on the Bayer pattern. In this paper we review a simple linear method using 5 x 5 filters, proposed by Malvar, He, and Cutler in 2004, that shows surprisingly good results.

  6. The I{sub c}(H)-T{sub c}(H) phase boundary of superconducting Nb thin films with periodic and quasiperiodic antidot arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bothner, D.; Kemmler, M.; Cozma, R.; Kleiner, R.; Koelle, D. [Physikalisches Institut and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Misko, V.; Peeters, F. [Departement Fysica, Universiteit Antwerpen (Belgium); Nori, F. [Advanced Science Institute, RIKEN (Japan)

    2011-07-01

    The magnetic field dependent critical current I{sub c}(H) of superconducting thin films with artificial defects strongly depends on the symmetry of the defect arrangement. Likewise the critical temperature T{sub c}(H) of superconducting wire networks is heavily influenced by the symmetry of the system. Here we present experimental data on the I{sub c}(H)-T{sub c}(H) phase boundary of Nb thin films with artificial defect lattices of different symmetries. For this purpose we fabricated 60 nm thick Nb films with antidots in periodic (triangular) and five different quasiperiodic arrangements. The parameters of the antidot arrays were varied to investigate the influence of antidot diameter and array density. Experiments were performed with high temperature stability ({delta}T<1 mK) at 0.5{<=}T/T{sub c}{<=}1. From the I-V-characteristics at variable H and T we extract I{sub c}(H) and T{sub c}(H) for different voltage and resistance criteria. The experimental data for the critical current density are compared with results from numerical molecular dynamics simulations.

  7. Transport and Dispersion of Nanoparticles in Periodic Nanopost Arrays

    KAUST Repository

    He, Kai; Retterer, Scott T.; Srijanto, Bernadeta R.; Conrad, Jacinta C.; Krishnamoorti, Ramanan

    2014-01-01

    Nanoparticles transported through highly confined porous media exhibit faster breakthrough than small molecule tracers. Despite important technological applications in advanced materials, human health, energy, and environment, the microscale mechanisms leading to early breakthrough have not been identified. Here, we measure dispersion of nanoparticles at the single-particle scale in regular arrays of nanoposts and show that for highly confined flows of dilute suspensions of nanoparticles the longitudinal and transverse velocities exhibit distinct scaling behaviors. The distributions of transverse particle velocities become narrower and more non-Gaussian when the particles are strongly confined. As a result, the transverse dispersion of highly confined nanoparticles at low Péclet numbers is significantly less important than longitudinal dispersion, leading to early breakthrough. This finding suggests a fundamental mechanism by which to control dispersion and thereby improve efficacy of nanoparticles applied for advanced polymer nanocomposites, drug delivery, hydrocarbon production, and environmental remediation. © 2014 American Chemical Society.

  8. Transport and Dispersion of Nanoparticles in Periodic Nanopost Arrays

    KAUST Repository

    He, Kai

    2014-05-27

    Nanoparticles transported through highly confined porous media exhibit faster breakthrough than small molecule tracers. Despite important technological applications in advanced materials, human health, energy, and environment, the microscale mechanisms leading to early breakthrough have not been identified. Here, we measure dispersion of nanoparticles at the single-particle scale in regular arrays of nanoposts and show that for highly confined flows of dilute suspensions of nanoparticles the longitudinal and transverse velocities exhibit distinct scaling behaviors. The distributions of transverse particle velocities become narrower and more non-Gaussian when the particles are strongly confined. As a result, the transverse dispersion of highly confined nanoparticles at low Péclet numbers is significantly less important than longitudinal dispersion, leading to early breakthrough. This finding suggests a fundamental mechanism by which to control dispersion and thereby improve efficacy of nanoparticles applied for advanced polymer nanocomposites, drug delivery, hydrocarbon production, and environmental remediation. © 2014 American Chemical Society.

  9. 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

  10. Periodically patterned structures for nanoplasmonic and biomedical applications

    Science.gov (United States)

    Peer, Akshit

    Periodically patterned nanostructures have imparted profound impact on diverse scientific disciplines. In physics, chemistry, and materials science, artificially engineered photonic crystals have demonstrated an unprecedented ability to control the propagation of photons through light concentration and diffraction. The field of photonic crystals has led to many technical advances in fabricating periodically patterned nanostructures in dielectric/metallic materials and controlling the light-matter interactions at the nanoscale. In the field of biomaterials, it is of great interest to apply our knowledge base of photonic materials and explore how such periodically patterned structures control diverse biological functions by varying the available surface area, which is a key attribute for surface hydrophobicity, cell growth and drug delivery. Here we describe closely related scientific applications of large-scale periodically patterned polymers and metal nanostructures. The dissertation starts with nanoplasmonics for improving photovoltaic devices, where we design and optimize experimentally realizable light-trapping nanostructures using rigorous scattering matrix simulations for enhancing the performance of organic and perovskite solar cells. The use of periodically patterned plasmonic metal cathode in conjunction with polymer microlens array significantly improves the absorption in solar cells, providing new opportunities for photovoltaic device design. We further show the unprecedented ability of nanoplasmonics to concentrate light at the nanoscale by designing a large-area plasmonic nanocup array with frequency-selective optical transmission. The fabrication of nanostructure is achieved by coating non-uniform gold layer over a submicron periodic nanocup array imprinted on polystyrene using soft lithography. The gold nanocup array shows extraordinary optical transmission at a wavelength close to the structure period. The resonance wavelength for transmission can be

  11. 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.

  12. Order quantification of hexagonal periodic arrays fabricated by in situ solvent-assisted nanoimprint lithography of block copolymers

    International Nuclear Information System (INIS)

    Simão, Claudia; Khunsin, Worawut; Kehagias, Nikolaos; Sotomayor Torres, Clivia M; Salaun, Mathieu; Zelsmann, Marc; Morris, Michael A

    2014-01-01

    Directed self-assembly of block copolymer polystyrene-b-polyethylene oxide (PS-b-PEO) thin film was achieved by a one-pot methodology of solvent vapor assisted nanoimprint lithography (SAIL). Simultaneous solvent-anneal and imprinting of a PS-b-PEO thin film on silicon without surface pre-treatments yielded a 250 nm line grating decorated with 20 nm diameter nanodots array over a large surface area of up to 4′ wafer scale. The grazing-incidence small-angle x-ray scattering diffraction pattern showed the fidelity of the NIL stamp pattern replication and confirmed the periodicity of the BCP of 40 nm. The order of the hexagonally arranged nanodot lattice was quantified by SEM image analysis using the opposite partner method and compared to conventionally solvent-annealed block copolymer films. The imprint-based SAIL methodology thus demonstrated an improvement in ordering of the nanodot lattice of up to 50%, and allows significant time and cost reduction in the processing of these structures. (papers)

  13. Synthesis of concentric circular antenna arrays using dragonfly algorithm

    Science.gov (United States)

    Babayigit, B.

    2018-05-01

    Due to the strong non-linear relationship between the array factor and the array elements, concentric circular antenna array (CCAA) synthesis problem is challenging. Nature-inspired optimisation techniques have been playing an important role in solving array synthesis problems. Dragonfly algorithm (DA) is a novel nature-inspired optimisation technique which is based on the static and dynamic swarming behaviours of dragonflies in nature. This paper presents the design of CCAAs to get low sidelobes using DA. The effectiveness of the proposed DA is investigated in two different (with and without centre element) cases of two three-ring (having 4-, 6-, 8-element or 8-, 10-, 12-element) CCAA design. The radiation pattern of each design cases is obtained by finding optimal excitation weights of the array elements using DA. Simulation results show that the proposed algorithm outperforms the other state-of-the-art techniques (symbiotic organisms search, biogeography-based optimisation, sequential quadratic programming, opposition-based gravitational search algorithm, cat swarm optimisation, firefly algorithm, evolutionary programming) for all design cases. DA can be a promising technique for electromagnetic problems.

  14. Assessing non-linear variation of temperature and precipitation for different growth periods of maize and their impacts on phenology in the Midwest of Jilin Province, China

    Science.gov (United States)

    Guo, Enliang; Zhang, Jiquan; Wang, Yongfang; Alu, Si; Wang, Rui; Li, Danjun; Ha, Si

    2018-05-01

    In the past two decades, the regional climate in China has undergone significant change, resulting in crop yield reduction and complete failure. The goal of this study is to detect the variation of temperature and precipitation for different growth periods of maize and assess their impact on phenology. The daily meteorological data in the Midwest of Jilin Province during 1960-2014 were used in the study. The ensemble empirical mode decomposition method was adopted to analyze the non-linear trend and fluctuation in temperature and precipitation, and the sensitivity of the length of the maize growth period to temperature and precipitation was analyzed by the wavelet cross-transformation method. The results show that the trends of temperature and precipitation change are non-linear for different growth periods of maize, and the average temperature in the sowing-jointing stage was different from that in the other growth stages, showing a slight decrease trend, while the variation amplitude of maximum temperature is smaller than that of the minimum temperature. This indicates that the temperature difference between day and night shows a gradually decreasing trend. Precipitation in the growth period also showed a decreasing non-linear trend, while the inter-annual variability with period of quasi-3-year and quasi-6-year dominated the variation of temperature and precipitation. The whole growth period was shortened by 10.7 days, and the sowing date was advanced by approximately 11 days. We also found that there was a significant resonance period among temperature, precipitation, and phenology. Overall, a negative correlation between phenology and temperature is evident, while a positive correlation with precipitation is exhibited. The results illustrate that the climate suitability for maize has reduced over the past decades.

  15. Array capabilities and future arrays

    International Nuclear Information System (INIS)

    Radford, D.

    1993-01-01

    Early results from the new third-generation instruments GAMMASPHERE and EUROGAM are confirming the expectation that such arrays will have a revolutionary effect on the field of high-spin nuclear structure. When completed, GAMMASHPERE will have a resolving power am order of magnitude greater that of the best second-generation arrays. When combined with other instruments such as particle-detector arrays and fragment mass analysers, the capabilites of the arrays for the study of more exotic nuclei will be further enhanced. In order to better understand the limitations of these instruments, and to design improved future detector systems, it is important to have some intelligible and reliable calculation for the relative resolving power of different instrument designs. The derivation of such a figure of merit will be briefly presented, and the relative sensitivities of arrays currently proposed or under construction presented. The design of TRIGAM, a new third-generation array proposed for Chalk River, will also be discussed. It is instructive to consider how far arrays of Compton-suppressed Ge detectors could be taken. For example, it will be shown that an idealised open-quote perfectclose quotes third-generation array of 1000 detectors has a sensitivity an order of magnitude higher again than that of GAMMASPHERE. Less conventional options for new arrays will also be explored

  16. Optical analogue of relativistic Dirac solitons in binary waveguide arrays

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Truong X., E-mail: truong.tran@mpl.mpg.de [Department of Physics, Le Quy Don University, 236 Hoang Quoc Viet str., 10000 Hanoi (Viet Nam); Max Planck Institute for the Science of Light, Günther-Scharowsky str. 1, 91058 Erlangen (Germany); Longhi, Stefano [Department of Physics, Politecnico di Milano and Istituto di Fotonica e Nanotecnologie del Consiglio Nazionale delle Ricerche, Piazza L. da Vinci 32, I-20133 Milano (Italy); Biancalana, Fabio [Max Planck Institute for the Science of Light, Günther-Scharowsky str. 1, 91058 Erlangen (Germany); School of Engineering and Physical Sciences, Heriot-Watt University, EH14 4AS Edinburgh (United Kingdom)

    2014-01-15

    We study analytically and numerically an optical analogue of Dirac solitons in binary waveguide arrays in the presence of Kerr nonlinearity. Pseudo-relativistic soliton solutions of the coupled-mode equations describing dynamics in the array are analytically derived. We demonstrate that with the found soliton solutions, the coupled mode equations can be converted into the nonlinear relativistic 1D Dirac equation. This paves the way for using binary waveguide arrays as a classical simulator of quantum nonlinear effects arising from the Dirac equation, something that is thought to be impossible to achieve in conventional (i.e. linear) quantum field theory. -- Highlights: •An optical analogue of Dirac solitons in nonlinear binary waveguide arrays is suggested. •Analytical solutions to pseudo-relativistic solitons are presented. •A correspondence of optical coupled-mode equations with the nonlinear relativistic Dirac equation is established.

  17. Co-Prime Frequency and Aperture Design for HF Surveillance, Wideband Radar Imaging, and Nonstationary Array Processing

    Science.gov (United States)

    2018-03-01

    to develop novel co-prime sampling and array design strategies that achieve high-resolution estimation of spectral power distributions and signal...by the array geometry and the frequency offset. We overcome this limitation by introducing a novel sparsity-based multi-target localization approach...estimation using a sparse uniform linear array with two CW signals of co-prime frequencies,” IEEE International Workshop on Computational Advances

  18. ERAASR: an algorithm for removing electrical stimulation artifacts from multielectrode array recordings

    Science.gov (United States)

    O'Shea, Daniel J.; Shenoy, Krishna V.

    2018-04-01

    Objective. Electrical stimulation is a widely used and effective tool in systems neuroscience, neural prosthetics, and clinical neurostimulation. However, electrical artifacts evoked by stimulation prevent the detection of spiking activity on nearby recording electrodes, which obscures the neural population response evoked by stimulation. We sought to develop a method to clean artifact-corrupted electrode signals recorded on multielectrode arrays in order to recover the underlying neural spiking activity. Approach. We created an algorithm, which performs estimation and removal of array artifacts via sequential principal components regression (ERAASR). This approach leverages the similar structure of artifact transients, but not spiking activity, across simultaneously recorded channels on the array, across pulses within a train, and across trials. The ERAASR algorithm requires no special hardware, imposes no requirements on the shape of the artifact or the multielectrode array geometry, and comprises sequential application of straightforward linear methods with intuitive parameters. The approach should be readily applicable to most datasets where stimulation does not saturate the recording amplifier. Main results. The effectiveness of the algorithm is demonstrated in macaque dorsal premotor cortex using acute linear multielectrode array recordings and single electrode stimulation. Large electrical artifacts appeared on all channels during stimulation. After application of ERAASR, the cleaned signals were quiescent on channels with no spontaneous spiking activity, whereas spontaneously active channels exhibited evoked spikes which closely resembled spontaneously occurring spiking waveforms. Significance. We hope that enabling simultaneous electrical stimulation and multielectrode array recording will help elucidate the causal links between neural activity and cognition and facilitate naturalistic sensory protheses.

  19. The behavior of the critical current density below and above the first matching field in superconductors with periodic square arrays of pinning sites

    International Nuclear Information System (INIS)

    Obaidat, I.M.; Al Khawaja, U.; Benkraouda, M.; Salmeen, N.

    2006-01-01

    We have studied the effect of the applied magnetic field on critical depinning force at zero and finite temperatures and for several values of pinning strength. This was achieved by conducting extensive series of molecular dynamic simulations on driven vortex lattices interacting with periodic square arrays of pinning sites. We have found that the critical depinning force decreases as the applied magnetic field is increased. We have also observed two distinct behaviors of dependence of the critical depinning force on the applied magnetic field below and above the first matching filed

  20. Fabrication of High-Frequency pMUT Arrays on Silicon Substrates

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Zawada, Tomasz; Hansen, Karsten

    2010-01-01

    A novel technique based on silicon micromachining for fabrication of linear arrays of high-frequency piezoelectric micromachined ultrasound transducers (pMUT) is presented. Piezoelectric elements are formed by deposition of lead zirconia titanate into etched features of a silicon substrate...

  1. What Else Is Decidable about Integer Arrays?

    OpenAIRE

    Habermehl, Peter; Iosif, Radu; Vojnar, Tomáš

    2008-01-01

    International audience; We introduce a new decidable logic for reasoning about infinite arrays of integers. The logic is in the ∃ * ∀ * first-order fragment and allows (1) Presburger constraints on existentially quantified variables, (2) difference constraints as well as periodicity constraints on universally quantified indices, and (3) difference constraints on values. In particular, using our logic, one can express constraints on consecutive elements of arrays (e.g. ∀i. 0 ≤ i < n → a[i + 1]...

  2. Excitation of high density surface plasmon polariton vortex array

    Science.gov (United States)

    Kuo, Chun-Fu; Chu, Shu-Chun

    2018-06-01

    This study proposes a method to excite surface plasmon polariton (SPP) vortex array of high spatial density on metal/air interface. A doughnut vector beam was incident at four rectangularly arranged slits to excite SPP vortex array. The doughnut vector beam used in this study has the same field intensity distribution as the regular doughnut laser mode, TEM01* mode, but a different polarization distribution. The SPP vortex array is achieved through the matching of both polarization state and phase state of the incident doughnut vector beam with the four slits. The SPP field distribution excited in this study contains stable array-distributed time-varying optical vortices. Theoretical derivation, analytical calculation and numerical simulation were used to discuss the characteristics of the induced SPP vortex array. The period of the SPP vortex array induced by the proposed method had only half SPPs wavelength. In addition, the vortex number in an excited SPP vortex array can be increased by enlarging the structure.

  3. Highly Sensitive Multi-Channel IDC Sensor Array for Low Concentration Taste Detection

    Directory of Open Access Journals (Sweden)

    Md. Rajibur Rahaman Khan

    2015-06-01

    Full Text Available In this study, we designed and developed an interdigitated capacitor (IDC-based taste sensor array to detect different taste substances. The designed taste sensing array has four IDC sensing elements. The four IDC taste sensing elements of the array are fabricated by incorporating four different types of lipids into the polymer, dioctyl phenylphosphonate (DOPP and tetrahydrofuran (THF to make the respective dielectric materials that are individually placed onto an interdigitated electrode (IDE via spin coating. When the dielectric material of an IDC sensing element comes into contact with a taste substance, its dielectric properties change with the capacitance of the IDC sensing element; this, in turn, changes the voltage across the IDC, as well as the output voltage of each channel of the system. In order to assess the effectiveness of the sensing system, four taste substances, namely sourness (HCl, saltiness (NaCl, sweetness (glucose and bitterness (quinine-HCl, were tested. The IDC taste sensor array had rapid response and recovery times of about 12.9 s and 13.39 s, respectively, with highly stable response properties. The response property of the proposed IDC taste sensor array was linear, and its correlation coefficient R2 was about 0.9958 over the dynamic range of the taste sensor array as the taste substance concentration was varied from 1 μM to 1 M. The proposed IDC taste sensor array has several other advantages, such as real-time monitoring capabilities, high sensitivity 45.78 mV/decade, good reproducibility with a standard deviation of about 0.029 and compactness, and the circuitry is based on readily available and inexpensive electronic components. The proposed IDC taste sensor array was compared with the potentiometric taste sensor with respect to sensitivity, dynamic range width, linearity and response time. We found that the proposed IDC sensor array has better performance. Finally, principal component analysis (PCA was applied

  4. Linear response theory an analytic-algebraic approach

    CERN Document Server

    De Nittis, Giuseppe

    2017-01-01

    This book presents a modern and systematic approach to Linear Response Theory (LRT) by combining analytic and algebraic ideas. LRT is a tool to study systems that are driven out of equilibrium by external perturbations. In particular the reader is provided with a new and robust tool to implement LRT for a wide array of systems. The proposed formalism in fact applies to periodic and random systems in the discrete and the continuum. After a short introduction describing the structure of the book, its aim and motivation, the basic elements of the theory are presented in chapter 2. The mathematical framework of the theory is outlined in chapters 3–5: the relevant von Neumann algebras, noncommutative $L^p$- and Sobolev spaces are introduced; their construction is then made explicit for common physical systems; the notion of isopectral perturbations and the associated dynamics are studied. Chapter 6 is dedicated to the main results, proofs of the Kubo and Kubo-Streda formulas. The book closes with a chapter about...

  5. 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.

  6. A linear laser-driver array for optical transmission in the LHC experiments

    CERN Document Server

    Cervelli, G; Moreira, P; Vasey, F

    2000-01-01

    A 4-way linear laser driver has been designed and implemented in a commercial 0.25 mu m CMOS technology. The full-custom IC is intended for analogue and digital data transmission as part of the 50 000 optical fibre links of the CMS particle tracking system. Intrinsic radiation tolerance and specific design methodologies enable the device to operate over 10 years in the harsh radiation environment of the innermost LHC detectors. Although optimised for analogue operation the driver is compatible with LVDS digital signalling. A combination of linearization methods achieves good analogue performance (8-bit equivalent dynamic range with a bandwidth of 100 MHz), while maintaining wide input common-mode range (+or-350 mV) and limited power dissipation. The linearly amplified signal is added to a DC current, which can be set over a wide range (-60 mA to +60 mA). The latter capability allows tracking of changes in laser threshold due to ageing or radiation damage. The driver gain and bias current are set via a serial ...

  7. An IBM PC-based math model for space station solar array simulation

    Science.gov (United States)

    Emanuel, E. M.

    1986-01-01

    This report discusses and documents the design, development, and verification of a microcomputer-based solar cell math model for simulating the Space Station's solar array Initial Operational Capability (IOC) reference configuration. The array model is developed utilizing a linear solar cell dc math model requiring only five input parameters: short circuit current, open circuit voltage, maximum power voltage, maximum power current, and orbit inclination. The accuracy of this model is investigated using actual solar array on orbit electrical data derived from the Solar Array Flight Experiment/Dynamic Augmentation Experiment (SAFE/DAE), conducted during the STS-41D mission. This simulator provides real-time simulated performance data during the steady state portion of the Space Station orbit (i.e., array fully exposed to sunlight). Eclipse to sunlight transients and shadowing effects are not included in the analysis, but are discussed briefly. Integrating the Solar Array Simulator (SAS) into the Power Management and Distribution (PMAD) subsystem is also discussed.

  8. The multi-period solution of a linear system of equations with the operator of differentiation along the main diagonal of the space of independent variables and delayed arguments

    Science.gov (United States)

    Sartabanov, Zhaishylyk A.

    2017-09-01

    A new approach to the study of periodic by all independent variables system of equations with a differentiation operator solutions along the direction of the main diagonal and with delayed arguments is proposed. The essence of the approach is to reduce the study of the multi-periodic solution of a linear inhomogeneous system to the construction of a solution of a simpler linear differential-difference system on the basis of the method of variating arbitrary constants of the complete integral of a homogeneous system. An integral representation of the unique multiperiodic solution of an inhomogeneous system is presented, expressed by a functional series of terms given by multiple repeated integrals. An estimate is given for the norm of a multi-periodic solution.

  9. Iterative algorithms for large sparse linear systems on parallel computers

    Science.gov (United States)

    Adams, L. M.

    1982-01-01

    Algorithms for assembling in parallel the sparse system of linear equations that result from finite difference or finite element discretizations of elliptic partial differential equations, such as those that arise in structural engineering are developed. Parallel linear stationary iterative algorithms and parallel preconditioned conjugate gradient algorithms are developed for solving these systems. In addition, a model for comparing parallel algorithms on array architectures is developed and results of this model for the algorithms are given.

  10. Shallow velocity structure of Stromboli Volcano, Italy, derived from small-aperture array measurements of Strombolian tremor

    Science.gov (United States)

    Chouet, B.; De Luca, G.; Milana, G.; Dawson, P.; Martini, M.; Scarpa, R.

    1998-01-01

    The properties of the tremor wave field at Stromboli are analyzed using data from small-aperture arrays of short-period seismometers deployed on the north flank of the volcano. The seismometers are configued in two semi-circular arrays with radii of 60 and 150 m and a linear array with length of 600 m. The data are analyzed using a spatiotemporal correlation technique specifically designed for the study of the stationary stochastic wave field of Rayleigh and Love waves generated by volcanic activity and by scattering sources distributed within the island. The correlation coefficients derived as a function of frequency for the three components of motion clearly define the dispersion characteristics for both Rayleigh and Love waves. Love and Rayleigh waves contribute 70% and 30%, respectively, of the surface-wave power. The phase velocities of Rayleigh waves range from 1000 m/sec at 2 Hz to 350 m/sec at 9 Hz, and those for Love waves range from 700 to 400 m/sec over the same frequency band. These velocities are similar to those measured near Puu Oo on the east rift of Kilauea Volcano, Hawaii, although the dispersion characteristics of Rayleigh waves at Stromboli show a stronger dependence on frequency. Such low velocities are consistent with values expected for densely cracked solidified basalt. The dispersion curves are inverted for a velocity model beneath the arrays, assuming those dispersions represent the fundamental modes of Rayleigh and Love waves.

  11. Improvement of Data Acquisition of the BRTR (PS-43) Seismic Array

    Science.gov (United States)

    Ozel, N. M.; Kocak, S.; Semin, K. U.; Necmioglu, O.; Destici, T. C.; Teoman, U.

    2010-05-01

    Bogazici University, Kandilli Observatory and Earthquake Research Institute(KOERI) is currently operating the BRTR( PS-43) seismic arrays located in the vicinity of Ankara and town Keskin, providing real-time data to IDC. PS-43 is composed of two sub-arrays, the medium-period array with a ~45km radius located in Ankara and the short-period array with ~3 km radius located in Keskin. In 2009, data availabilty of the BRTR is exceeded %98 that value is the requirment of IDC. Substantial contribution to obtain this availabiliy is implementing the improvements that mainly replacement of the grid type parabolic antennas with the heavy-duty dish antennas at necessary sites called the repeater sites RE-BRTR (CCF), RE-PS43 (Mt. Elmadag), CF-PS43 (Central Recording Building) and all MP sites. Even this renewed system is at the tentative stage, communication status of the seismic arrays are solid and continuous. BRTR is expecting another improvement, June 2010, about the power system at Mt. Elmadag and the MP site BR237. Completion of this improvement will be stabilize of our current mission.

  12. Uncooled infrared focal plane array imaging in China

    Science.gov (United States)

    Lei, Shuyu

    2015-06-01

    This article reviews the development of uncooled infrared focal plane array (UIFPA) imaging in China in the past decade. Sensors based on optical or electrical read-out mechanism were developed but the latter dominates the market. In resistive bolometers, VOx and amorphous silicon are still the two major thermal-sensing materials. The specifications of the IRFPA made by different manufactures were collected and compared. Currently more than five Chinese companies and institutions design and fabricate uncooled infrared focal plane array. Some devices have sensitivity as high as 30 mK; the largest array for commercial products is 640×512 and the smallest pixel size is 17 μm. Emphasis is given on the pixel MEMS design, ROIC design, fabrication, and packaging of the IRFPA manufactured by GWIC, especially on design for high sensitivities, low noise, better uniformity and linearity, better stabilization for whole working temperature range, full-digital design, etc.

  13. A recurrent neural network for adaptive beamforming and array correction.

    Science.gov (United States)

    Che, Hangjun; Li, Chuandong; He, Xing; Huang, Tingwen

    2016-08-01

    In this paper, a recurrent neural network (RNN) is proposed for solving adaptive beamforming problem. In order to minimize sidelobe interference, the problem is described as a convex optimization problem based on linear array model. RNN is designed to optimize system's weight values in the feasible region which is derived from arrays' state and plane wave's information. The new algorithm is proven to be stable and converge to optimal solution in the sense of Lyapunov. So as to verify new algorithm's performance, we apply it to beamforming under array mismatch situation. Comparing with other optimization algorithms, simulations suggest that RNN has strong ability to search for exact solutions under the condition of large scale constraints. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator

    Directory of Open Access Journals (Sweden)

    Maria Calado

    2012-06-01

    Full Text Available This paper proposes a distributed system for analysis and monitoring (DSAM of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs. The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.

  15. An intelligent sensor array distributed system for vibration analysis and acoustic noise characterization of a linear switched reluctance actuator.

    Science.gov (United States)

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.

  16. Heat and Mass Transfer during Hydrogen Generation in an Array of Fuel Bars of a BWR Using a Periodic Unit Cell

    Directory of Open Access Journals (Sweden)

    H. Romero-Paredes

    2012-01-01

    Full Text Available This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations.

  17. A superconducting quadrupole array for transport of multiple high current beams

    International Nuclear Information System (INIS)

    Faltens, A.; Shuman, D.

    1999-01-01

    We present a conceptual design of a superconducting quadrupole magnet array for the side-by-side transport of multiple high current particle beams in induction linear accelerators. The magnetic design uses a modified cosine 20 current distribution inside a square cell boundary. Each interior magnet's neighbors serve as the return flux paths and the poles are placed as close as possible to each other to facilitate this. No iron is present in the basic 2-D magnetic design; it will work at any current level without correction windings. Special 1/8th quadrupoles are used along the transverse periphery of the array to contain and channel flux back into the array, making every channel look as part of an infinite array. This design provides a fixed dimension array boundary equal to the quadrupole radius that can be used for arrays of any number of quadrupole channels, at any field level. More importantly, the design provides magnetic field separation between the array and the induction cores which may be surrounding it. Flux linkage between these two components can seriously affect the operation of both of them

  18. Multiwall carbon nanotube microcavity arrays

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Rajib; Butt, Haider, E-mail: h.butt@bham.ac.uk [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Rifat, Ahmmed A. [Integrated Lightwave Research Group, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 65 Landsdowne Street, Cambridge, Massachusetts 02139 (United States); Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)

    2016-03-21

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm{sup 2}) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170–180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  19. Two dimensional CCD [charged coupled device] arrays as parallel detectors in electron energy loss and x-ray wavelength dispersive spectroscopy

    International Nuclear Information System (INIS)

    Zaluzec, N.J.

    1988-08-01

    Parallel detection systems for spectroscopy have generally been based upon linear detector arrays. Replacing the linear arrays with two dimensional systems yields more complicated devices; however, there are corresponding benefits which can be realized for both x-ray and electron energy loss spectroscopy. The operational design of these systems, as well as preliminary results from the construction of such a device used for electron spectroscopy, are presented. 10 refs., 8 figs

  20. Realistic full wave modeling of focal plane array pixels.

    Energy Technology Data Exchange (ETDEWEB)

    Campione, Salvatore [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Warne, Larry K. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Jorgenson, Roy E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Electromagnetic Theory Dept.; Davids, Paul [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Applied Photonic Microsystems Dept.; Peters, David W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Applied Photonic Microsystems Dept.

    2017-11-01

    Here, we investigate full-wave simulations of realistic implementations of multifunctional nanoantenna enabled detectors (NEDs). We focus on a 2x2 pixelated array structure that supports two wavelengths of operation. We design each resonating structure independently using full-wave simulations with periodic boundary conditions mimicking the whole infinite array. We then construct a supercell made of a 2x2 pixelated array with periodic boundary conditions mimicking the full NED; in this case, however, each pixel comprises 10-20 antennas per side. In this way, the cross-talk between contiguous pixels is accounted for in our simulations. We observe that, even though there are finite extent effects, the pixels work as designed, each responding at the respective wavelength of operation. This allows us to stress that realistic simulations of multifunctional NEDs need to be performed to verify the design functionality by taking into account finite extent and cross-talk effects.

  1. 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 ... effects such as all-optical switching [7,8], nearly degenerate four-wave mixing [9,10], .... is driven by a radio frequency signal of 27.2MHz with a modulation available in.

  2. A FPGA-based signal processing unit for a GEM array detector

    International Nuclear Information System (INIS)

    Yen, W.W.; Chou, H.P.

    2013-06-01

    in the present study, a signal processing unit for a GEM one-dimensional array detector is presented to measure the trajectory of photoelectrons produced by cosmic X-rays. The present GEM array detector system has 16 signal channels. The front-end unit provides timing signals from trigger units and energy signals from charge sensitive amplifies. The prototype of the processing unit is implemented using commercial field programmable gate array circuit boards. The FPGA based system is linked to a personal computer for testing and data analysis. Tests using simulated signals indicated that the FPGA-based signal processing unit has a good linearity and is flexible for parameter adjustment for various experimental conditions (authors)

  3. Linear mixed models a practical guide using statistical software

    CERN Document Server

    West, Brady T; Galecki, Andrzej T

    2006-01-01

    Simplifying the often confusing array of software programs for fitting linear mixed models (LMMs), Linear Mixed Models: A Practical Guide Using Statistical Software provides a basic introduction to primary concepts, notation, software implementation, model interpretation, and visualization of clustered and longitudinal data. This easy-to-navigate reference details the use of procedures for fitting LMMs in five popular statistical software packages: SAS, SPSS, Stata, R/S-plus, and HLM. The authors introduce basic theoretical concepts, present a heuristic approach to fitting LMMs based on bo

  4. A Discrete Component Low-Noise Preamplifier Readout for a Linear (1x16) SiC Photodiode Array

    Science.gov (United States)

    Kahle, Duncan; Aslam, Shahid; Herrero, Frederico A.; Waczynski, Augustyn

    2016-01-01

    A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1x16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analogue signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

  5. A discrete component low-noise preamplifier readout for a linear (1×16) SiC photodiode array

    Energy Technology Data Exchange (ETDEWEB)

    Kahle, Duncan [NASA, Goddard Space Flight Center, Detector Systems Branch, Greenbelt, MD 20771 (United States); Aslam, Shahid, E-mail: shahid.aslam-1@nasa.gov [NASA, Goddard Space Flight Center, Planetary Systems Laboratory, Greenbelt, MD 20771 (United States); Herrero, Federico A.; Waczynski, Augustyn [NASA, Goddard Space Flight Center, Detector Systems Branch, Greenbelt, MD 20771 (United States)

    2016-09-11

    A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1×16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analog signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

  6. Weighted thinned linear array design with the iterative FFT technique

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2011-09-01

    Full Text Available techniques utilise simulated annealing [3]?[5], [10], mixed integer linear programming [7], genetic algorithms [9], and a hyrid approach combining a genetic algorithm and a local optimiser [8]. The iterative Fourier technique (IFT) developed by Keizer [2... algorithm being well- suited to obtaining low CTRs. Test problems from the literature are considered, and the results obtained with the IFT considerably exceed those achieved with other algorithms. II. DESCRIPTION OF THE ALGORITHM A flowchart describing...

  7. Linear distributed source modeling of local field potentials recorded with intra-cortical electrode arrays.

    Directory of Open Access Journals (Sweden)

    Rikkert Hindriks

    Full Text Available Planar intra-cortical electrode (Utah arrays provide a unique window into the spatial organization of cortical activity. Reconstruction of the current source density (CSD underlying such recordings, however, requires "inverting" Poisson's equation. For inter-laminar recordings, this is commonly done by the CSD method, which consists in taking the second-order spatial derivative of the recorded local field potentials (LFPs. Although the CSD method has been tremendously successful in mapping the current generators underlying inter-laminar LFPs, its application to planar recordings is more challenging. While for inter-laminar recordings the CSD method seems reasonably robust against violations of its assumptions, is it unclear as to what extent this holds for planar recordings. One of the objectives of this study is to characterize the conditions under which the CSD method can be successfully applied to Utah array data. Using forward modeling, we find that for spatially coherent CSDs, the CSD method yields inaccurate reconstructions due to volume-conducted contamination from currents in deeper cortical layers. An alternative approach is to "invert" a constructed forward model. The advantage of this approach is that any a priori knowledge about the geometrical and electrical properties of the tissue can be taken into account. Although several inverse methods have been proposed for LFP data, the applicability of existing electroencephalographic (EEG and magnetoencephalographic (MEG inverse methods to LFP data is largely unexplored. Another objective of our study therefore, is to assess the applicability of the most commonly used EEG/MEG inverse methods to Utah array data. Our main conclusion is that these inverse methods provide more accurate CSD reconstructions than the CSD method. We illustrate the inverse methods using event-related potentials recorded from primary visual cortex of a macaque monkey during a motion discrimination task.

  8. Arc arrays: studies of high resolution techniques for multibeam bathymetric applications

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.; Schenke, H.W.

    . This geometry is tested using the Bartlett method for varying arc and linear arrays of 30 - elements. We also examine `high resolution techniques' such as the Maximum LIkelihood (ML) method and the Maximum Entropy (ME) methods (different orders), for 16-element...

  9. Strong Laws of Large Numbers for Arrays of Rowwise NA and LNQD Random Variables

    Directory of Open Access Journals (Sweden)

    Jiangfeng Wang

    2011-01-01

    Full Text Available Some strong laws of large numbers and strong convergence properties for arrays of rowwise negatively associated and linearly negative quadrant dependent random variables are obtained. The results obtained not only generalize the result of Hu and Taylor to negatively associated and linearly negative quadrant dependent random variables, but also improve it.

  10. Sub-electron transport in single-electron-tunneling arrays

    Science.gov (United States)

    Kaplan, Daniel; Sverdlov, Viktor; Korotkov, Alexander; Likharev, Konstantin

    2002-03-01

    We have analyzed quasi-continuous charge transport in two-dimensional tunnel junction arrays with a special distribution of background charges, providing a complete suppression of Coulomb blockade thresholds of tunneling between any pair of islands. Numerical simulations show that at low currents the dc I-V curve is indeed linear, while the shot noise is strongly suppressed and approaches 1/N of the Schottky value (where N is the array length). Thus both conditions of quasi-continuous transport, formulated earlier by Matsuoka and Likharev (Phys. Rev. B, v57, 15613, 1998), are satisfied. At higher fields the electron-hole pair production begins, and shot noise grows sharply. At higher voltages still, the array enters the "plasma" regime (with nearly balanced number of electrons and holes) and the Fano factor drops to 1/N once again. We have studied the resulting shot noise peak in detail, and concluded that its physics is close to that of critical opalescence.

  11. Invariant submanifold for series arrays of Josephson junctions.

    Science.gov (United States)

    Marvel, Seth A; Strogatz, Steven H

    2009-03-01

    We study the nonlinear dynamics of series arrays of Josephson junctions in the large-N limit, where N is the number of junctions in the array. The junctions are assumed to be identical, overdamped, driven by a constant bias current, and globally coupled through a common load. Previous simulations of such arrays revealed that their dynamics are remarkably simple, hinting at the presence of some hidden symmetry or other structure. These observations were later explained by the discovery of N-3 constants of motion, the choice of which confines the resulting flow in phase space to a low-dimensional invariant manifold. Here we show that the dimensionality can be reduced further by restricting attention to a special family of states recently identified by Ott and Antonsen. In geometric terms, the Ott-Antonsen ansatz corresponds to an invariant submanifold of dimension one less than that found earlier. We derive and analyze the flow on this submanifold for two special cases: an array with purely resistive loading and another with resistive-inductive-capacitive loading. Our results recover (and in some instances improve) earlier findings based on linearization arguments.

  12. Evaluation of fiber Bragg grating sensor interrogation using InGaAs linear detector arrays and Gaussian approximation on embedded hardware

    Science.gov (United States)

    Kumar, Saurabh; Amrutur, Bharadwaj; Asokan, Sundarrajan

    2018-02-01

    Fiber Bragg Grating (FBG) sensors have become popular for applications related to structural health monitoring, biomedical engineering, and robotics. However, for successful large scale adoption, FBG interrogation systems are as important as sensor characteristics. Apart from accuracy, the required number of FBG sensors per fiber and the distance between the device in which the sensors are used and the interrogation system also influence the selection of the interrogation technique. For several measurement devices developed for applications in biomedical engineering and robotics, only a few sensors per fiber are required and the device is close to the interrogation system. For these applications, interrogation systems based on InGaAs linear detector arrays provide a good choice. However, their resolution is dependent on the algorithms used for curve fitting. In this work, a detailed analysis of the choice of algorithm using the Gaussian approximation for the FBG spectrum and the number of pixels used for curve fitting on the errors is provided. The points where the maximum errors occur have been identified. All comparisons for wavelength shift detection have been made against another interrogation system based on the tunable swept laser. It has been shown that maximum errors occur when the wavelength shift is such that one new pixel is included for curve fitting. It has also been shown that an algorithm with lower computation cost compared to the more popular methods using iterative non-linear least squares estimation can be used without leading to the loss of accuracy. The algorithm has been implemented on embedded hardware, and a speed-up of approximately six times has been observed.

  13. Changes in magnetic properties from solid state to solution in a trinuclear linear copper(II) complex

    NARCIS (Netherlands)

    Koval, I.A.; Akhideno, H.; Tanase, S.; Belle, C.; Duboc, C.; Saint-Aman, E.; Gamez, P.; Tooke, D.M.; Spek, A.L.; Pierre, J.-L.; Reedijk, J.

    2007-01-01

    A linear trinuclear copper(II) complex containing phenoxido- and alkoxido-bridges between the metal centers has been isolated and structurally characterized. The complex cation consists of a linear array of three copper ions, assembled by means of two doubly deprotonated ligands. The octahedral

  14. Spectral statistics and scattering resonances of complex primes arrays

    Science.gov (United States)

    Wang, Ren; Pinheiro, Felipe A.; Dal Negro, Luca

    2018-01-01

    We introduce a class of aperiodic arrays of electric dipoles generated from the distribution of prime numbers in complex quadratic fields (Eisenstein and Gaussian primes) as well as quaternion primes (Hurwitz and Lifschitz primes), and study the nature of their scattering resonances using the vectorial Green's matrix method. In these systems we demonstrate several distinctive spectral properties, such as the absence of level repulsion in the strongly scattering regime, critical statistics of level spacings, and the existence of critical modes, which are extended fractal modes with long lifetimes not supported by either random or periodic systems. Moreover, we show that one can predict important physical properties, such as the existence spectral gaps, by analyzing the eigenvalue distribution of the Green's matrix of the arrays in the complex plane. Our results unveil the importance of aperiodic correlations in prime number arrays for the engineering of gapped photonic media that support far richer mode localization and spectral properties compared to usual periodic and random media.

  15. 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

  16. Micro-Drilling of Polymer Tubular Ultramicroelectrode Arrays for Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Niels B. Larsen

    2013-05-01

    Full Text Available We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene (PEDOT, a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

  17. Lithographically patterned electrodeposition of gold, silver, and nickel nanoring arrays with widely tunable near-infrared plasmonic resonances.

    Science.gov (United States)

    Halpern, Aaron R; Corn, Robert M

    2013-02-26

    A novel low-cost nanoring array fabrication method that combines the process of lithographically patterned nanoscale electrodeposition (LPNE) with colloidal lithography is described. Nanoring array fabrication was accomplished in three steps: (i) a thin (70 nm) sacrificial nickel or silver film was first vapor-deposited onto a plasma-etched packed colloidal monolayer; (ii) the polymer colloids were removed from the surface, a thin film of positive photoresist was applied, and a backside exposure of the photoresist was used to create a nanohole electrode array; (iii) this array of nanoscale cylindrical electrodes was then used for the electrodeposition of gold, silver, or nickel nanorings. Removal of the photoresist and sacrificial metal film yielded a nanoring array in which all of the nanoring dimensions were set independently: the inter-ring spacing was fixed by the colloidal radius, the radius of the nanorings was controlled by the plasma etching process, and the width of the nanorings was controlled by the electrodeposition process. A combination of scanning electron microscopy (SEM) measurements and Fourier transform near-infrared (FT-NIR) absorption spectroscopy were used to characterize the nanoring arrays. Nanoring arrays with radii from 200 to 400 nm exhibited a single strong NIR plasmonic resonance with an absorption maximum wavelength that varied linearly from 1.25 to 3.33 μm as predicted by a simple standing wave model linear antenna theory. This simple yet versatile nanoring array fabrication method was also used to electrodeposit concentric double gold nanoring arrays that exhibited multiple NIR plasmonic resonances.

  18. KTOE, KEDAK to ENDF/B Format Conversion with Linear Linear Interpolation

    International Nuclear Information System (INIS)

    Panini, Gian Carlo

    1985-01-01

    1 - Nature of physical problem solved: This code performs a fully automated translation from KEDAK into ENDF-4 or -5 format. Output is on tape in card image format. 2 - Method of solution: Before translation the reactions are sorted in the ENDF format order. Linear-linear interpolation rule is preserved. The resonance parameters for both resolved and unresolved, could also be translated and a background cross section is formed as the difference of the calculated contribution from the parameters and the point-wise data given in the original file. Elastic angular distributions originally given in tabulated form are converted into Legendre polynomial coefficients. Energy distributions are calculated using a simple evaporation model with the temperature expressed as a function of the incident mass. 3 - Restrictions on the complexity of the problem: The existing restrictions both on KEDAK and ENDF have been applied to the array sizes used in the code, except for the number of points in a section which in the ENDF format are limited to 5000 points. The code only translates one material at a time

  19. An Effective Amperometric Biosensor Based on Gold Nanoelectrode Arrays

    Directory of Open Access Journals (Sweden)

    Zhu Yingchun

    2008-01-01

    Full Text Available Abstract A sensitive amperometric biosensor based on gold nanoelectrode array (NEA was investigated. The gold nanoelectrode array was fabricated by template-assisted electrodeposition on general electrodes, which shows an ordered well-defined 3D structure of nanowires. The sensitivity of the gold NEA to hydrogen peroxide is 37 times higher than that of the conventional electrode. The linear range of the platinum NEA toward H2O2is from 1 × 10−6to 1 × 10−2 M, covering four orders of magnitudes with detection limit of 1 × 10−7 M and a single noise ratio (S/N of four. The enzyme electrode exhibits an excellent response performance to glucose with linear range from 1 × 10−5to 1 × 10−2 M and a fast response time within 8 s. The Michaelis–Menten constantkm and the maximum current densityi maxof the enzyme electrode were 4.97 mM and 84.60 μA cm−2, respectively. This special nanoelectrode may find potential application in other biosensors based on amperometric signals.

  20. Measuring the linear heat generation rate of a nuclear reactor fuel pin

    International Nuclear Information System (INIS)

    Smith, R.D.

    1981-01-01

    A miniature gamma thermometer is described which is capable of travelling through bores distributed in an array through a nuclear reactor core and measure the linear heat generation rate of the fuel pins. (U.K.)

  1. Amperometric Morphine Detection Using Pt-Co Alloy Nanowire Array-modified Electrode

    International Nuclear Information System (INIS)

    Tao, Manlan; Xu, Feng; Li, Yueting; Xu, Quanqing; Chang, Yanbing; Yang, Yunhui; Wu, Zaisheng

    2010-01-01

    Pt-Co alloy nanowire array was directly synthesized by electrochemical deposition with polycarbonate template at -1.0V and subsequent chemical etching of the template. The use of Pt-Co alloy nanowire array-modified electrode (Pt- Co NAE) for the determination of morphine (MO) is described. The morphology of the Pt-Co alloy nanowire array has been investigated by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS) analysis), respectively. The resulting Pt-Co NAE offered a linear amperometric response for morphine ranging from 2.35 x 10 -5 to 2.39 x 10 -3 M with a detection limit of 7.83 x 10 -6 M at optimum conditions. This sensor displayed high sensitivity and long-term stability

  2. Measuring the electromagnetic chirality of 2D arrays under normal illumination.

    Science.gov (United States)

    Garcia-Santiago, X; Burger, S; Rockstuhl, C; Fernandez-Corbaton, I

    2017-10-15

    We present an electromagnetic chirality measure for 2D arrays of subwavelength periodicities under normal illumination. The calculation of the measure uses only the complex reflection and transmission coefficients from the array. The measure allows the ordering of arrays according to their electromagnetic chirality, which further allows a quantitative comparison of different design strategies. The measure is upper bounded, and the extreme properties of objects with high values of electromagnetic chirality make them useful in both near- and far-field applications. We analyze the consequences that different possible symmetries of the array have on its electromagnetic chirality. We use the measure to study four different arrays. The results indicate the suitability of helices for building arrays of high electromagnetic chirality, and the low effectiveness of a substrate for breaking the transverse mirror symmetry.

  3. Fault Detection Using the Clustering-kNN Rule for Gas Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Jingli Yang

    2016-12-01

    Full Text Available The k-nearest neighbour (kNN rule, which naturally handles the possible non-linearity of data, is introduced to solve the fault detection problem of gas sensor arrays. In traditional fault detection methods based on the kNN rule, the detection process of each new test sample involves all samples in the entire training sample set. Therefore, these methods can be computation intensive in monitoring processes with a large volume of variables and training samples and may be impossible for real-time monitoring. To address this problem, a novel clustering-kNN rule is presented. The landmark-based spectral clustering (LSC algorithm, which has low computational complexity, is employed to divide the entire training sample set into several clusters. Further, the kNN rule is only conducted in the cluster that is nearest to the test sample; thus, the efficiency of the fault detection methods can be enhanced by reducing the number of training samples involved in the detection process of each test sample. The performance of the proposed clustering-kNN rule is fully verified in numerical simulations with both linear and non-linear models and a real gas sensor array experimental system with different kinds of faults. The results of simulations and experiments demonstrate that the clustering-kNN rule can greatly enhance both the accuracy and efficiency of fault detection methods and provide an excellent solution to reliable and real-time monitoring of gas sensor arrays.

  4. Fault Detection Using the Clustering-kNN Rule for Gas Sensor Arrays

    Science.gov (United States)

    Yang, Jingli; Sun, Zhen; Chen, Yinsheng

    2016-01-01

    The k-nearest neighbour (kNN) rule, which naturally handles the possible non-linearity of data, is introduced to solve the fault detection problem of gas sensor arrays. In traditional fault detection methods based on the kNN rule, the detection process of each new test sample involves all samples in the entire training sample set. Therefore, these methods can be computation intensive in monitoring processes with a large volume of variables and training samples and may be impossible for real-time monitoring. To address this problem, a novel clustering-kNN rule is presented. The landmark-based spectral clustering (LSC) algorithm, which has low computational complexity, is employed to divide the entire training sample set into several clusters. Further, the kNN rule is only conducted in the cluster that is nearest to the test sample; thus, the efficiency of the fault detection methods can be enhanced by reducing the number of training samples involved in the detection process of each test sample. The performance of the proposed clustering-kNN rule is fully verified in numerical simulations with both linear and non-linear models and a real gas sensor array experimental system with different kinds of faults. The results of simulations and experiments demonstrate that the clustering-kNN rule can greatly enhance both the accuracy and efficiency of fault detection methods and provide an excellent solution to reliable and real-time monitoring of gas sensor arrays. PMID:27929412

  5. A pattern recognition approach to transistor array parameter variance

    Science.gov (United States)

    da F. Costa, Luciano; Silva, Filipi N.; Comin, Cesar H.

    2018-06-01

    The properties of semiconductor devices, including bipolar junction transistors (BJTs), are known to vary substantially in terms of their parameters. In this work, an experimental approach, including pattern recognition concepts and methods such as principal component analysis (PCA) and linear discriminant analysis (LDA), was used to experimentally investigate the variation among BJTs belonging to integrated circuits known as transistor arrays. It was shown that a good deal of the devices variance can be captured using only two PCA axes. It was also verified that, though substantially small variation of parameters is observed for BJT from the same array, larger variation arises between BJTs from distinct arrays, suggesting the consideration of device characteristics in more critical analog designs. As a consequence of its supervised nature, LDA was able to provide a substantial separation of the BJT into clusters, corresponding to each transistor array. In addition, the LDA mapping into two dimensions revealed a clear relationship between the considered measurements. Interestingly, a specific mapping suggested by the PCA, involving the total harmonic distortion variation expressed in terms of the average voltage gain, yielded an even better separation between the transistor array clusters. All in all, this work yielded interesting results from both semiconductor engineering and pattern recognition perspectives.

  6. Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Andrea Trucco

    2015-06-01

    Full Text Available For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed. In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

  7. Linear-motion tattoo machine and prefabricated needle sets for the delivery of plant viruses by vascular puncture inoculation

    Science.gov (United States)

    Vascular puncture inoculation (VPI) of plant viruses previously has been conducted either manually or by use of a commercial engraving tool and laboratory-fabricated needle arrays. In an effort to improve this technique, a linear-motion tattoo machine driving industry-standard needle arrays was tes...

  8. A Novel Approach for Analysis of the Log-Linear Age-Period-Cohort Model: Application to Lung Cancer Incidence

    Directory of Open Access Journals (Sweden)

    Tengiz Mdzinarishvili

    2009-12-01

    Full Text Available A simple, computationally efficient procedure for analyses of the time period and birth cohort effects on the distribution of the age-specific incidence rates of cancers is proposed. Assuming that cohort effects for neighboring cohorts are almost equal and using the Log-Linear Age-Period-Cohort Model, this procedure allows one to evaluate temporal trends and birth cohort variations of any type of cancer without prior knowledge of the hazard function. This procedure was used to estimate the influence of time period and birth cohort effects on the distribution of the age-specific incidence rates of first primary, microscopically confirmed lung cancer (LC cases from the SEER9 database. It was shown that since 1975, the time period effect coefficients for men increase up to 1980 and then decrease until 2004. For women, these coefficients increase from 1975 up to 1990 and then remain nearly constant. The LC birth cohort effect coefficients for men and women increase from the cohort of 1890–94 until the cohort of 1925–29, then decrease until the cohort of 1950–54 and then remain almost unchanged. Overall, LC incidence rates, adjusted by period and cohort effects, increase up to the age of about 72–75, turn over, and then fall after the age of 75–78. The peak of the adjusted rates in men is around the age of 77–78, while in women, it is around the age of 72–73. Therefore, these results suggest that the age distribution of the incidence rates in men and women fall at old ages.

  9. Electrostatic interactions in finite systems treated with periodic boundary conditions: application to linear-scaling density functional theory.

    Science.gov (United States)

    Hine, Nicholas D M; Dziedzic, Jacek; Haynes, Peter D; Skylaris, Chris-Kriton

    2011-11-28

    We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within density functional theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement, and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb interaction combined with padding of the simulation cell, approaches based on the minimum image convention, and the explicit use of open boundary conditions (OBCs). We have implemented these approaches in the ONETEP LS-DFT program and applied them to a range of systems, including a polar nanorod and a protein. We compare their accuracy, complexity, and rate of convergence with simulation cell size. We demonstrate that corrective approaches within PBCs can achieve the OBC result more efficiently and accurately than pure OBC approaches.

  10. Computer Drawing Method for Operating Characteristic Curve of PV Power Plant Array Unit

    Science.gov (United States)

    Tan, Jianbin

    2018-02-01

    According to the engineering design of large-scale grid-connected photovoltaic power stations and the research and development of many simulation and analysis systems, it is necessary to draw a good computer graphics of the operating characteristic curves of photovoltaic array elements and to propose a good segmentation non-linear interpolation algorithm. In the calculation method, Component performance parameters as the main design basis, the computer can get 5 PV module performances. At the same time, combined with the PV array series and parallel connection, the computer drawing of the performance curve of the PV array unit can be realized. At the same time, the specific data onto the module of PV development software can be calculated, and the good operation of PV array unit can be improved on practical application.

  11. Superhydrophobic hierarchical arrays fabricated by a scalable colloidal lithography approach.

    Science.gov (United States)

    Kothary, Pratik; Dou, Xuan; Fang, Yin; Gu, Zhuxiao; Leo, Sin-Yen; Jiang, Peng

    2017-02-01

    Here we report an unconventional colloidal lithography approach for fabricating a variety of periodic polymer nanostructures with tunable geometries and hydrophobic properties. Wafer-sized, double-layer, non-close-packed silica colloidal crystal embedded in a polymer matrix is first assembled by a scalable spin-coating technology. The unusual non-close-packed crystal structure combined with a thin polymer film separating the top and the bottom colloidal layers render great versatility in templating periodic nanostructures, including arrays of nanovoids, nanorings, and hierarchical nanovoids. These different geometries result in varied fractions of entrapped air in between the templated nanostructures, which in turn lead to different apparent water contact angles. Superhydrophobic surfaces with >150° water contact angles and <5° contact angle hysteresis are achieved on fluorosilane-modified polymer hierarchical nanovoid arrays with large fractions of entrapped air. The experimental contact angle measurements are complemented with theoretical predictions using the Cassie's model to gain insights into the fundamental microstructure-dewetting property relationships. The experimental and theoretical contact angles follow the same trends as determined by the unique hierarchical structures of the templated periodic arrays. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection

    Directory of Open Access Journals (Sweden)

    San-Shan Hung

    2016-12-01

    Full Text Available A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2′-bipyridyl dichlororuthenium(II hexahydrate and Tris(bipyridineruthenium(II chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

  13. A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection.

    Science.gov (United States)

    Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

    2016-12-08

    A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

  14. Technical evaluation of Solar Cells, Inc., CdTe module and array at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Kroposki, B.; Strand, T.; Hansen, R. [National Renewable Energy Lab., Golden, CO (United States); Powell, R.; Sasala, R. [Solar Cells, Inc., Toledo, OH (United States)

    1996-05-01

    The Engineering and Technology Validation Team at the National Renewable Energy Laboratory (NREL) conducts in-situ technical evaluations of polycrystalline thin-film photovoltaic (PV) modules and arrays. This paper focuses on the technical evaluation of Solar Cells, Inc., (SCI) cadmium telluride (CdTe) module and array performance by attempting to correlate individual module and array performance. This is done by examining the performance and stability of the modules and array over a period of more than one year. Temperature coefficients for module and array parameters (P{sub max}, V{sub oc}, V{sub max}, I{sub sc}, I{sub max}) are also calculated.

  15. Properties of Repetitive Long-Period Seismicity at Villarrica Volcano, Chile

    Science.gov (United States)

    Richardson, J.; Waite, G. P.; Palma, J.; Johnson, J. B.

    2011-12-01

    Villarrica Volcano, Chile hosts a persistent lava lake and is characterized by degassing and long-period seismicity. In order to better understand the relationship between outgassing and seismicity, we recorded broadband seismic and acoustic data along with high-rate SO2 emission data. We used both a densely-spaced linear array deployed on the northern flank of Villarrica, during the austral summer of 2011, and a wider aperture array of stations distributed around the volcano that was active in the austral summer of 2010. Both deployments consisted of three-component broadband stations and were augmented with broadband infrasound sensors. Of particular interests are repetitive, ~1 Hz seismic and coincident infrasound signals that occurred approximately every 2 minutes. Because these events are typically very low amplitude, we used a matched filter approach to identify them. We windowed several high-amplitude records of these events from broadband seismic stations near the vent. The record section of each event served as a template to compare with the entire dataset by cross-correlation. This approach identified ~20,000 nearly identical events during the ~7 day deployment of the linear array, which were otherwise difficult to identify in the raw records. Assuming that all of the events that we identified have identical source mechanisms and depths, we stack the large suite of events to produce low-noise records and particle motions at receivers farther than 5 km from the vent. We find that the records from stations near the edifice are dominated by tangential particle motion, suggesting the influence of near-field components. Correlation of these data with broadband acoustic data collected at the summit suggest that these repeatable seismic processes are linked to acoustic emissions, probably due to gas bubbles bursting at the magma free surface, as no eruptive products besides gas were being emitted by the volcano during the instrument deployment. The acoustic

  16. Multichannel long period seismic data acquisition system

    International Nuclear Information System (INIS)

    Kolvankar, V.G.; Rao, D.S.

    1990-01-01

    This paper discusses the specifications and performance of an eight channel long period seismic digital data acquisition system, which is developed and installed at Seismic Array Station, Gauribidanur, Karnataka State. The paper describes how these data in an unedited form are recorded on a single track of magnetic tape inter-mittantly, which has resulted in recording of 50 days data on a single tapespool. A time indexing technique which enables quick access to any desired portion of a recorded tape is also discussed. Typical examples of long period seismic event signals recorded by this system are also illustrated. Various advantages, the system provides over the analog multichannel instrumentation tape recording system, operating at Seismic Array Station for th e last two decades, are also discussed. (author). 7 figs

  17. Element sharing in interleaved antenna arrays

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2012-03-01

    Full Text Available , there is a large variation in the results for a small number of shared elements which reduces as the number of times the GA is run increases. Taken together, these points suggest that the GA implemented here does not provide consistently good results when... levels in linear arrays,? IEEE Antennas Wirel. Propag. Lett., vol. 9, pp. 771?774, 2010. [11] D. E. Goldberg, Genetic algorithms in search, optimization, and machine learning. Addison-Wesley, 1989. [12] T. Blickle and L. Thiele, ?A comparison...

  18. Analysis of electromagnetic scattering by nearly periodic structures: an LDRD report.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, William Arthur; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wilton, Donald R. (University of Houston, Houston, TX); Basilio, Lorena I.; Peters, David William; Capolino, F. (University of Houston, Houston, TX)

    2006-10-01

    In this LDRD we examine techniques to analyze the electromagnetic scattering from structures that are nearly periodic. Nearly periodic could mean that one of the structure's unit cells is different from all the others--a defect. It could also mean that the structure is truncated, or butted up against another periodic structure to form a seam. Straightforward electromagnetic analysis of these nearly periodic structures requires us to grid the entire structure, which would overwhelm today's computers and the computers in the foreseeable future. In this report we will examine various approximations that allow us to continue to exploit some aspects of the structure's periodicity and thereby reduce the number of unknowns required for analysis. We will use the Green's Function Interpolation with a Fast Fourier Transform (GIFFT) to examine isolated defects both in the form of a source dipole over a meta-material slab and as a rotated dipole in a finite array of dipoles. We will look at the numerically exact solution of a one-dimensional seam. In order to solve a two-dimensional seam, we formulate an efficient way to calculate the Green's function of a 1d array of point sources. We next formulate ways of calculating the far-field due to a seam and due to array truncation based on both array theory and high-frequency asymptotic methods. We compare the high-frequency and GIFFT results. Finally, we use GIFFT to solve a simple, two-dimensional seam problem.

  19. Periodic solutions of nonlinear vibrating beams

    Directory of Open Access Journals (Sweden)

    J. Berkovits

    2003-01-01

    Full Text Available The aim of this paper is to prove new existence and multiplicity results for periodic semilinear beam equation with a nonlinear time-independent perturbation in case the period is not prescribed. Since the spectrum of the linear part varies with the period, the solvability of the equation depends crucially on the period which can be chosen as a free parameter. Since the period of the external forcing is generally unknown a priori, we consider the following natural problem. For a given time-independent nonlinearity, find periods T for which the equation is solvable for any T-periodic forcing. We will also deal with the existence of multiple solutions when the nonlinearity interacts with the spectrum of the linear part. We show that under certain conditions multiple solutions do exist for any small forcing term with suitable period T. The results are obtained via generalized Leray-Schauder degree and reductions to invariant subspaces.

  20. Cantilever arrayed blood pressure sensor for arterial applanation tonometry.

    Science.gov (United States)

    Lee, Byeungleul; Jeong, Jinwoo; Kim, Jinseok; Kim, Bonghwan; Chun, Kukjin

    2014-03-01

    The authors developed a cantilever-arrayed blood pressure sensor array fabricated by (111) silicon bulk-micromachining for the non-invasive and continuous measurement of blood pressure. The blood pressure sensor measures the blood pressure based on the change in the resistance of the piezoresistor on a 5-microm-thick-arrayed perforated membrane and 20-microm-thick metal pads. The length and the width of the unit membrane are 210 and 310 microm, respectively. The width of the insensible zone between the adjacent units is only 10 microm. The resistance change over contact force was measured to verify the performance. The good linearity of the result confirmed that the polydimethylsiloxane package transfers the forces appropriately. The measured sensitivity was about 4.5%/N. The maximum measurement range and the resolution of the fabricated blood pressure sensor were greater than 900 mmHg (= 120 kPa) and less than 1 mmHg (= 133.3 Pa), respectively.

  1. Standard practice for radiological examination using digital detector arrays

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice establishes the minimum requirements for radiological examination for metallic and nonmetallic material using a digital detector array (DDA) system. 1.2 The requirements in this practice are intended to control the quality of radiologic images and are not intended to establish acceptance criteria for parts or materials. 1.3 This practice covers the radiologic examination with DDAs including DDAs described in Practice E2597 such as a device that contains a photoconductor attached to a Thin Film Transistor (TFT) read out structure, a device that has a phosphor coupled directly to an amorphous silicon read-out structure, and devices where a phosphor is coupled to a CMOS (Complementary metal–oxide–semiconductor) array, a Linear Detector Array (LDA) or a CCD (charge coupled device) crystalline silicon read-out structure. 1.4 The DDA shall be selected for an NDT application based on knowledge of the technology described in Guide , and of the selected DDA properties provided by the manufactu...

  2. Location and wavefield attributes of long-period signals at Villarrica volcano (Chile) determined by array and polarization-moveout analysis

    Science.gov (United States)

    Lehr, Johanna; Thorwart, Martin; Rabbel, Wolfgang

    2016-04-01

    Villarrica Volcano is the most active volcano in Chile whose latest eruption occurred in March 2015. Increasing the knowledge on its processes, structure and behavior is thus crucial to an effective monitoring and hazard assessment. In this context, long-period volcanic signals (LP) are considered to be a key to the understanding of fluid dynamics and volcanic plumbing systems, accessible by seismological observations. However, standard seismological location tools usually fail due to the emergent onset of the signal and its serious distortion caused by attenuation and scattering in a complex geology. Therefore, alternative methods are needed. In March 2012, a dense seismic network was installed at Villarrica for two weeks with 50 stations covering the volcanic edifice including 6 subarrays. About 400 LP events were identified. LP-events recorded on crater stations look similar to typical earthquakes arrivals with distinguishable P- and S-wave onsets indicating a source near the crater. But with increasing source distance waveforms gradually change into typical LP-events. To investigate how to locate these LP-events we tested two approaches at the basis of a show-case event. In a first trial, records of the subarrays were used to determine backazimuths and slowness by beamforming in the time domain. The analysis was performed in a moving window, using semblance to measure the beam quality. The epicenter was derived by intersecting azimuthal rays. It locates ca. 1 km southeast of the summit crater. Slownesses range from 0.5 s/km up to 2.0 s/km. At frequencies above 2 Hz, additional maxima appear in the semblance distribution of near-summit arrays which can be interpreted as side-scattered signals. Since the crossing points of the backazimuth rays showed some scattering we tested polarization analysis (applied to the subset of 3-component stations) as an alternative location method. Although the direct interpretation of the backazimuths was unreliable, we identified

  3. Non-Linear Metamodeling Extensions to the Robust Parameter Design of Computer Simulations

    Science.gov (United States)

    2016-09-15

    The combined-array RSM approach has been applied to a piston simulation [11] and an economic order quantity inventory model [12, 13]. A textbook ...are limited when applied to simulations. In the former case, the mean and variance models can be inadequate due to a high level of non-linearity...highly non-linear nature of typical simulations. In the multi-response RPD problem, the objective is to find the optimal control parameter levels

  4. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  5. Thin-film sparse boundary array design for passive acoustic mapping during ultrasound therapy.

    Science.gov (United States)

    Coviello, Christian M; Kozick, Richard J; Hurrell, Andrew; Smith, Penny Probert; Coussios, Constantin-C

    2012-10-01

    A new 2-D hydrophone array for ultrasound therapy monitoring is presented, along with a novel algorithm for passive acoustic mapping using a sparse weighted aperture. The array is constructed using existing polyvinylidene fluoride (PVDF) ultrasound sensor technology, and is utilized for its broadband characteristics and its high receive sensitivity. For most 2-D arrays, high-resolution imagery is desired, which requires a large aperture at the cost of a large number of elements. The proposed array's geometry is sparse, with elements only on the boundary of the rectangular aperture. The missing information from the interior is filled in using linear imaging techniques. After receiving acoustic emissions during ultrasound therapy, this algorithm applies an apodization to the sparse aperture to limit side lobes and then reconstructs acoustic activity with high spatiotemporal resolution. Experiments show verification of the theoretical point spread function, and cavitation maps in agar phantoms correspond closely to predicted areas, showing the validity of the array and methodology.

  6. Method and system for homogenizing diode laser pump arrays

    Science.gov (United States)

    Bayramian, Andy J

    2013-10-01

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  7. A Macintosh based data system for array spectrometers (Poster)

    Science.gov (United States)

    Bregman, J.; Moss, N.

    An interactive data aquisition and reduction system has been assembled by combining a Macintosh computer with an instrument controller (an Apple II computer) via an RS-232 interface. The data system provides flexibility for operating different linear array spectrometers. The standard Macintosh interface is used to provide ease of operation and to allow transferring the reduced data to commercial graphics software.

  8. Specific features of implosion of metallized fiber arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Breshkov, S. S. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2017-02-15

    Implosion of metallized fiber arrays was studied experimentally at the Angara-5-1 facility. The use of such arrays makes it possible to investigate the production and implosion dynamics of plasmas of various metals (such as tin, indium, and bismuth) that were previously unavailable for such studies. The plasma production rates m-dot (in μg/(cm{sup 2} ns)) for different metals were determined and quantitatively compared. Varying the thickness of the metal layer deposited on kapron fibers (the total linear mass of the metal coating being maintained at the level of 220 μg/cm), the current and velocity of the plasma precursor were studied as functions of the thickness of the metal coating. The strong difference in the rates of plasma production from the metal coating and kapron fibers results in the redistribution of the discharge current between the Z-pinch and the trailing fiber plasma. The outer boundary of the plasma produced from the metal coating is found to be stable against instabilities typical of the final stage of implosion of conventional wire arrays.

  9. Frequency characteristics of coordinate sequences of linear recurrences over Galois rings

    Science.gov (United States)

    Kamlovskii, O. V.

    2013-12-01

    We consider some properties of the coordinate sequences of linear recurrences over Galois rings which characterize the possibility of regarding them as pseudo-random sequences. We study the periodicity properties, linear complexity and frequency characteristics of these sequences. Up to now, these parameters have been studied mainly in the case when the linear recurring sequence has maximal possible period. We investigate the coordinate sequences of linear recurrences of not necessarily maximal period. We obtain sharpened and generalized estimates for the number of elements and r-patterns on the cycles and intervals of these sequences.

  10. Frequency characteristics of coordinate sequences of linear recurrences over Galois rings

    International Nuclear Information System (INIS)

    Certification Research Center, Moscow (Russian Federation))" data-affiliation=" (LLC Certification Research Center, Moscow (Russian Federation))" >Kamlovskii, O V

    2013-01-01

    We consider some properties of the coordinate sequences of linear recurrences over Galois rings which characterize the possibility of regarding them as pseudo-random sequences. We study the periodicity properties, linear complexity and frequency characteristics of these sequences. Up to now, these parameters have been studied mainly in the case when the linear recurring sequence has maximal possible period. We investigate the coordinate sequences of linear recurrences of not necessarily maximal period. We obtain sharpened and generalized estimates for the number of elements and r-patterns on the cycles and intervals of these sequences

  11. Controlling optical properties of periodic gold nanoparticle arrays by changing the substrate, topologic shapes of nanoparticles, and polarization direction of incident light

    International Nuclear Information System (INIS)

    Ting, Li; Li, Yu; Zhi-Xin, Lu; Gang, Song; Kai, Zhang

    2011-01-01

    The effects of various parameters including thickness and dielectric constants of substrates, shapes of nanoparticles, and polarization direction of incident light, on the extinction spectra of periodic gold nanoparticle arrays are investigated by the full-vectorial three-dimensional (3D) finite difference time domain (FDTD) method. The calculated results show that the substrate affects the extinction spectra by coupling the fields co-excited by the substrate and gold nanoparticles. Extinction spectra are influenced by the shapes of the nanoparticles, but there are no obvious changes in extinction spectra for similar shapes. The polarization direction of incident light has a great influence on the extinction spectra. The implications of these results are discussed. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. Focal plane array with modular pixel array components for scalability

    Science.gov (United States)

    Kay, Randolph R; Campbell, David V; Shinde, Subhash L; Rienstra, Jeffrey L; Serkland, Darwin K; Holmes, Michael L

    2014-12-09

    A modular, scalable focal plane array is provided as an array of integrated circuit dice, wherein each die includes a given amount of modular pixel array circuitry. The array of dice effectively multiplies the amount of modular pixel array circuitry to produce a larger pixel array without increasing die size. Desired pixel pitch across the enlarged pixel array is preserved by forming die stacks with each pixel array circuitry die stacked on a separate die that contains the corresponding signal processing circuitry. Techniques for die stack interconnections and die stack placement are implemented to ensure that the desired pixel pitch is preserved across the enlarged pixel array.

  13. X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR)

    DEFF Research Database (Denmark)

    Krawczynski, Henric S.; Stern, Daniel; Harrison, Fiona A.

    2016-01-01

    This paper describes the Polarization Spectroscopic Telescope Array (PolSTAR), a mission proposed to NASA's 2014 Small Explorer (SMEX) announcement of opportunity. PolSTAR measures the linear polarization of 3-50 keV (requirement; goal: 2.5-70 keV) X-rays probing the behavior of matter,radiation ...

  14. Rectification of light refraction in curved waveguide arrays.

    Science.gov (United States)

    Longhi, Stefano

    2009-02-15

    An "optical ratchet" for discretized light in photonic lattices, which enables observing rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically curved zigzag waveguide arrays is proposed.

  15. 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

  16. Large displacement bi-directional out-of-plane Lorentz actuator array for surface manipulation

    International Nuclear Information System (INIS)

    Park, Byoungyoul; Afsharipour, Elnaz; Chrusch, Dwayne; Shafai, Cyrus; Andersen, David; Burley, Greg

    2017-01-01

    This paper presents a large displacement out-of-plane Lorentz actuator array for surface manipulation. Actuators are formed from single crystal silicon flexible serpentine springs on either side of a rigid crossbar containing a narrow contact pillar. A rigid mounting rail system was employed to enable a 5  ×  5 array, which offers scalability of the array size. Analytical and finite element models were used to optimize actuator design. Individual actuators were tested to show linear deflection response of  ±150 µ m motion, using a  ±14.7 mA current in the presence of a 0.48 T magnetic field. This actuator array is suitable for various 2D surface modification applications due to its large deformation with low current and temperature of operation, and narrow contact area to a target surface. (paper)

  17. 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

  18. Linear LIDAR versus Geiger-mode LIDAR: impact on data properties and data quality

    Science.gov (United States)

    Ullrich, A.; Pfennigbauer, M.

    2016-05-01

    LIDAR has become the inevitable technology to provide accurate 3D data fast and reliably even in adverse measurement situations and harsh environments. It provides highly accurate point clouds with a significant number of additional valuable attributes per point. LIDAR systems based on Geiger-mode avalanche photo diode arrays, also called single photon avalanche photo diode arrays, earlier employed for military applications, now seek to enter the commercial market of 3D data acquisition, advertising higher point acquisition speeds from longer ranges compared to conventional techniques. Publications pointing out the advantages of these new systems refer to the other category of LIDAR as "linear LIDAR", as the prime receiver element for detecting the laser echo pulses - avalanche photo diodes - are used in a linear mode of operation. We analyze the differences between the two LIDAR technologies and the fundamental differences in the data they provide. The limitations imposed by physics on both approaches to LIDAR are also addressed and advantages of linear LIDAR over the photon counting approach are discussed.

  19. Monolithic blue LED series arrays for high-voltage AC operation

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping [Satellite Venture Business Laboratory, University of Tokushima, Tokushima 770-8506 (Japan); Sato, Hisao; Mizobuchi, Takashi; Morioka, Kenji; Kawano, Shunsuke; Muramoto, Yoshihiko; Sato, Daisuke; Sakai, Shiro [Nitride Semiconductor Co. Ltd., Naruto, Tokushima 771-0360 (Japan); Lee, Young-Bae; Ohno, Yasuo [Department of Electrical and Electronic Engineering, University of Tokushima, Tokushima 770-8506 (Japan)

    2002-12-16

    Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 {mu}m x 120 {mu}m and the total size is 1.1 mm x 1 mm for a 40(20+20) LED array. Deep dry etching was performed as device isolation. Two-layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On-wafer measurement shows that the output power is 40 mW for 40(20+20) LED array under ac 72 V. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  20. 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)

  1. Square and Rectangular Arrays from Directed Assembly of Sphere-forming Diblock Copolymers in Thin Films

    Science.gov (United States)

    Ji, Shengxiang; Nagpal, Umang; Liao, Wen; de Pablo, Juan; Nealey, Paul

    2010-03-01

    Patterns of square and rectangular arrays with nanoscale dimensions are scientifically and technologically important. Fabrication of square array patterns in thin films has been demonstrated by directed assembly of cylinder-forming diblock copolymers on chemically patterned substrates, supramolecular assembly of diblock copolymers, and self-assembly of triblock terpolymers. However, a macroscopic area of square array patterns with long-range order has not been achieved, and the fabrication of rectangular arrays has not been reported so far. Here we report a facile approach for fabricating patterns of square and rectangular arrays by directing the assembly of sphere-forming diblock copolymers on chemically patterned substrates. On stripe patterns, a square arrangement of half spheres, corresponding to the (100) plane of the body-centred cubic (BCC) lattice, formed on film surfaces. When the underlying pattern periods mismatched with the copolymer period, the square pattern could be stretched (up to ˜60%) or compressed (˜15%) to form rectangular arrays. Monte Carlo simulations have been further used to verify the experimental results and the 3-dimensional arrangements of spheres.

  2. Rectification of light refraction in curved waveguide arrays

    OpenAIRE

    Longhi, S.

    2010-01-01

    An 'optical ratchet' for discretized light in photonic lattices, which enables to observe rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically-curved zigzag waveguide arrays is proposed.

  3. Biodegradation mechanism of linear alkylbenzenesulfonate-14C

    International Nuclear Information System (INIS)

    Kubodera, Tadayoshi; Muto, Toshio; Yamamoto, Tatsuo

    1978-01-01

    The biodegradation of linear alkylbenzenesulfonate- 14 C (LAS- 14 C) tagged with 14 C at the linear side chain was studied on activated sludge by tracer method in addition to the methylene blue method which is widely employed in the biodegradation of LAS. It was found that there were three periods of rapid adsorption period, acclimation period, and degradation process. The radiolysis of dodecylbenzenesulfonate was studied on irradiating by 5000 Ci 60 Co source. The decomposition products were identified by GLC and GC-MS spectrometry after desulfonation. 1-Tetralone, 1-indanone, 4-methyl-1-tetralone, naphthalene et al. were found in them. (author)

  4. ArrayBridge: Interweaving declarative array processing with high-performance computing

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Haoyuan [The Ohio State Univ., Columbus, OH (United States); Floratos, Sofoklis [The Ohio State Univ., Columbus, OH (United States); Blanas, Spyros [The Ohio State Univ., Columbus, OH (United States); Byna, Suren [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prabhat, Prabhat [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wu, Kesheng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Brown, Paul [Paradigm4, Inc., Waltham, MA (United States)

    2017-05-04

    Scientists are increasingly turning to datacenter-scale computers to produce and analyze massive arrays. Despite decades of database research that extols the virtues of declarative query processing, scientists still write, debug and parallelize imperative HPC kernels even for the most mundane queries. This impedance mismatch has been partly attributed to the cumbersome data loading process; in response, the database community has proposed in situ mechanisms to access data in scientific file formats. Scientists, however, desire more than a passive access method that reads arrays from files. This paper describes ArrayBridge, a bi-directional array view mechanism for scientific file formats, that aims to make declarative array manipulations interoperable with imperative file-centric analyses. Our prototype implementation of ArrayBridge uses HDF5 as the underlying array storage library and seamlessly integrates into the SciDB open-source array database system. In addition to fast querying over external array objects, ArrayBridge produces arrays in the HDF5 file format just as easily as it can read from it. ArrayBridge also supports time travel queries from imperative kernels through the unmodified HDF5 API, and automatically deduplicates between array versions for space efficiency. Our extensive performance evaluation in NERSC, a large-scale scientific computing facility, shows that ArrayBridge exhibits statistically indistinguishable performance and I/O scalability to the native SciDB storage engine.

  5. Enhanced THz extinction in arrays of resonant semiconductor particles.

    Science.gov (United States)

    Schaafsma, Martijn C; Georgiou, Giorgos; Rivas, Jaime Gómez

    2015-09-21

    We demonstrate experimentally the enhanced THz extinction by periodic arrays of resonant semiconductor particles. This phenomenon is explained in terms of the radiative coupling of localized resonances with diffractive orders in the plane of the array (Rayleigh anomalies). The experimental results are described by numerical calculations using a coupled dipole model and by Finite-Difference in Time-Domain simulations. An optimum particle size for enhancing the extinction efficiency of the array is found. This optimum is determined by the frequency detuning between the localized resonances in the individual particles and the Rayleigh anomaly. The extinction calculations and measurements are also compared to near-field simulations illustrating the optimum particle size for the enhancement of the near-field.

  6. Switched periodic systems in discrete time: stability and input-output norms

    Science.gov (United States)

    Bolzern, Paolo; Colaneri, Patrizio

    2013-07-01

    This paper deals with the analysis of stability and the characterisation of input-output norms for discrete-time periodic switched linear systems. Such systems consist of a network of time-periodic linear subsystems sharing the same state vector and an exogenous switching signal that triggers the jumps between the subsystems. The overall system exhibits a complex dynamic behaviour due to the interplay between the time periodicity of the subsystem parameters and the switching signal. Both arbitrary switching signals and signals satisfying a dwell-time constraint are considered. Linear matrix inequality conditions for stability and guaranteed H2 and H∞ performances are provided. The results heavily rely on the merge of the theory of linear periodic systems and recent developments on switched linear time-invariant systems.

  7. 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.

  8. Linear accelerator with x-ray absorbing insulators

    International Nuclear Information System (INIS)

    Rose, P.H.

    1975-01-01

    Annular insulators for supporting successive annular electrodes in a linear accelerator have embedded x-ray absorbing shield structures extending around the accelerating path. The shield members are disposed to intercept x-ray radiation without disrupting the insulative effect of the insulator members. In preferred forms, the structure comprises a plurality of annular members of heavy metal disposed in an x-ray blocking array, spaced from each other by the insulating substance of the insulator member. (auth)

  9. Enhanced Light Narrow Transmission through Cascaded Metallic Structure with Periodic Aperture Arrays

    International Nuclear Information System (INIS)

    Yang Hong-Yan; Zhong Yan-Ru; Xiao Gong-Li; Zhang Zhen-Rong

    2012-01-01

    We present experimental and numerical studies on the enhanced light narrow transmission through cascaded Au/SiO x N y /Au aperture arrays by varying the refractive index and thickness of SiO x N y . It is found that the enhancement as well as narrowing of the optical transmission originates from the coupling role of surface plasmon polaritons. The results indicate that the transmission enhancement is highly dependent on the refractive index and thickness of SiO x N y . A higher transmission efficiency and narrower peak are obtained in Au/SiO 2.1 N 0.3 /Au structure with a small refractive index (1.6) and thin thickness (0.2 μm)

  10. Geometrical optimization of microstripe arrays for microbead magnetophoresis

    DEFF Research Database (Denmark)

    Henriksen, Anders Dahl; Rozlosnik, Noemi; Hansen, Mikkel Fougt

    2015-01-01

    Manipulation of magnetic beads plays an increasingly important role in molecular diagnostics. Magnetophoresis is a promising technique for selective transportation of magnetic beads in lab-on-a-chip systems. We investigate periodic arrays of exchange-biased permalloy microstripes fabricated using...

  11. Design and experimental validation of Unilateral Linear Halbach magnet arrays for single-sided magnetic resonance.

    Science.gov (United States)

    Bashyam, Ashvin; Li, Matthew; Cima, Michael J

    2018-07-01

    Single-sided NMR has the potential for broad utility and has found applications in healthcare, materials analysis, food quality assurance, and the oil and gas industry. These sensors require a remote, strong, uniform magnetic field to perform high sensitivity measurements. We demonstrate a new permanent magnet geometry, the Unilateral Linear Halbach, that combines design principles from "sweet-spot" and linear Halbach magnets to achieve this goal through more efficient use of magnetic flux. We perform sensitivity analysis using numerical simulations to produce a framework for Unilateral Linear Halbach design and assess tradeoffs between design parameters. Additionally, the use of hundreds of small, discrete magnets within the assembly allows for a tunable design, improved robustness to variability in magnetization strength, and increased safety during construction. Experimental validation using a prototype magnet shows close agreement with the simulated magnetic field. The Unilateral Linear Halbach magnet increases the sensitivity, portability, and versatility of single-sided NMR. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Bounded and Periodic Solutions of Semilinear Impulsive Periodic System on Banach Spaces

    Directory of Open Access Journals (Sweden)

    Wei W

    2008-01-01

    Full Text Available Abstract A class of semilinear impulsive periodic system on Banach spaces is considered. First, we introduce the -periodic PC-mild solution of semilinear impulsive periodic system. By virtue of Gronwall lemma with impulse, the estimate on the PC-mild solutions is derived. The continuity and compactness of the new constructed Poincaré operator determined by impulsive evolution operator corresponding to homogenous linear impulsive periodic system are shown. This allows us to apply Horn's fixed-point theorem to prove the existence of -periodic PC-mild solutions when PC-mild solutions are ultimate bounded. This extends the study on periodic solutions of periodic system without impulse to periodic system with impulse on general Banach spaces. At last, an example is given for demonstration.

  13. Refractive index dispersion sensing using an array of photonic crystal resonant reflectors

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron

    2015-01-01

    Refractive index sensing plays a key role in various environmental and biological sensing applications. Here, a method is presented for measuring the absolute refractive index dispersion of liquids using an array of photonic crystal resonant reflectors of varying periods. It is shown that by cove......Refractive index sensing plays a key role in various environmental and biological sensing applications. Here, a method is presented for measuring the absolute refractive index dispersion of liquids using an array of photonic crystal resonant reflectors of varying periods. It is shown...... that by covering the array with a sample liquid and measuring the resonance wavelength associated with transverse electric polarized quasi guided modes as a function of period, the refractive index dispersion of the liquid can be accurately obtained using an analytical expression. This method is compact, can...... perform measurements at arbitrary number of wavelengths, and requires only a minute sample volume. The ability to sense a material's dispersion profile offers an added dimension of information that may be of benefit to optofluidic lab-on-a-chip applications. © 2015 AIP Publishing LLC....

  14. Globally exponential synchronization in an array of asymmetric coupled neural networks

    International Nuclear Information System (INIS)

    Lu Jianquan; Ho, Daniel W.C.; Liu Ming

    2007-01-01

    In this Letter, we study the globally exponential synchronization in an array of linearly coupled neural networks with delayed coupling. The coupling configuration matrix is assumed to be asymmetric, which is more coincident with the real-world network. The difficulty arising from the asymmetry of the coupling matrix has been overcame in this work. Some synchronization criteria are given in terms of strict linear matrix inequalities (LMIs), which can be efficiently solved by using interior point algorithm. Some previous synchronization results are generalized. Numerical simulation is also given to verify our theoretical analysis

  15. Variable-Period Undulators For Synchrotron Radiation

    Science.gov (United States)

    Shenoy, Gopal; Lewellen, John; Shu, Deming; Vinokurov, Nikolai

    2005-02-22

    A new and improved undulator design is provided that enables a variable period length for the production of synchrotron radiation from both medium-energy and high-energy storage rings. The variable period length is achieved using a staggered array of pole pieces made up of high permeability material, permanent magnet material, or an electromagnetic structure. The pole pieces are separated by a variable width space. The sum of the variable width space and the pole width would therefore define the period of the undulator. Features and advantages of the invention include broad photon energy tunability, constant power operation and constant brilliance operation.

  16. Variable-Period Undulators for Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Shenoy, Gopal; Lewellen, John; Shu, Deming; Vinokurov, Nikolai

    2005-02-22

    A new and improved undulator design is provided that enables a variable period length for the production of synchrotron radiation from both medium-energy and high energy storage rings. The variable period length is achieved using a staggered array of pole pieces made up of high permeability material, permanent magnet material, or an electromagnetic structure. The pole pieces are separated by a variable width space. The sum of the variable width space and the pole width would therefore define the period of the undulator. Features and advantages of the invention include broad photon energy tunability, constant power operation and constant brilliance operation.

  17. ATMAD: robust image analysis for Automatic Tissue MicroArray De-arraying.

    Science.gov (United States)

    Nguyen, Hoai Nam; Paveau, Vincent; Cauchois, Cyril; Kervrann, Charles

    2018-04-19

    developed a novel de-arraying approach for TMA analysis. By combining wavelet-based detection, active contour segmentation, and thin-plate spline interpolation, our approach is able to handle TMA images with high dynamic, poor signal-to-noise ratio, complex background and non-linear deformation of TMA grid. In addition, the deformation estimation produces quantitative information to asset the manufacturing quality of TMAs.

  18. Controllability analysis of decentralised linear controllers for polymeric fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Serra, Maria; Aguado, Joaquin; Ansede, Xavier; Riera, Jordi [Institut de Robotica i Informatica Industrial, Universitat Politecnica de Catalunya - Consejo Superior de Investigaciones Cientificas, C. Llorens i Artigas 4, 08028 Barcelona (Spain)

    2005-10-10

    This work deals with the control of polymeric fuel cells. It includes a linear analysis of the system at different operating points, the comparison and selection of different control structures, and the validation of the controlled system by simulation. The work is based on a complex non linear model which has been linearised at several operating points. The linear analysis tools used are the Morari resiliency index, the condition number, and the relative gain array. These techniques are employed to compare the controllability of the system with different control structures and at different operating conditions. According to the results, the most promising control structures are selected and their performance with PI based diagonal controllers is evaluated through simulations with the complete non linear model. The range of operability of the examined control structures is compared. Conclusions indicate good performance of several diagonal linear controllers. However, very few have a wide operability range. (author)

  19. Photodiode 1 × 64 linear array based on a double p-InAsSbP/n-InAs{sub 0.92}Sb{sub 0.08}/n{sup +}-InAs heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Il’inskaya, N. D., E-mail: ioffeled@mail.ru; Karandashev, S. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Karpukhina, N. G. [Limited Liability Company Ioffe LED Ltd. (Russian Federation); Lavrov, A. A.; Matveev, B. A.; Remennyi, M. A.; Stus, N. M.; Usikova, A. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation)

    2016-05-15

    The results of studies of the current–voltage characteristics and of the photoelectric and luminescence properties of a monolithic diode 1 × 64 linear array based on p-InAsSbP/n-InAsSb/n{sup +}-InAs with the n{sup +}-InAs-substrate side illuminated and sensitive in the region of 4-μm are reported. An analysis is performed of the mechanisms of current flow in the temperature range of 77–353 K and also of the photosensitivity and the speed of response taking into account the spatial distribution of nonequilibrium radiation and the data of capacitance–voltage measurements.

  20. 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.

  1. 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.

  2. The linear and nonlinear response of infinite periodic systems to static and/or dynamic electric fields. Implementation in CRYSTAL code

    Energy Technology Data Exchange (ETDEWEB)

    Kirtman, Bernard [Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 (United States); Springborg, Michael [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrücken (Germany); Rérat, Michel [Equipe de Chimie Physique, IPREM UMR5254, Université de Pau et des Pays de l' Adour, 64000 Pau (France); Ferrero, Mauro; Lacivita, Valentina; Dovesi, Roberto [Departimeno di Chimica, IFM, Università di Torino and NIS - Nanostructure Interfaces and Surfaces - Centre of Excellence, Via P. Giuria 7, 10125 Torino (Italy); Orlando, Roberto [Departimento di Scienze e Tecnologie Avanzati, Università del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria (Italy)

    2015-01-22

    An implementation of the vector potential approach (VPA) for treating the response of infinite periodic systems to static and dynamic electric fields has been initiated within the CRYSTAL code. The VPA method is based on the solution of a time-dependent Hartree-Fock or Kohn-Sham equation for the crystal orbitals wherein the usual scalar potential, that describes interaction with the field, is replaced by the vector potential. This equation may be solved either by perturbation theory or by finite field methods. With some modification all the computational procedures of molecular ab initio quantum chemistry can be adapted for periodic systems. Accessible properties include the linear and nonlinear responses of both the nuclei and the electrons. The programming of static field pure electronic (hyper)polarizabilities has been successfully tested. Dynamic electronic (hyper)polarizabilities, as well as infrared and Raman intensities, are in progress while the addition of finite fields for calculation of vibrational (hyper)polarizabilities, through nuclear relaxation procedures, will begin shortly.

  3. 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.

  4. Array Phase Shifters: Theory and Technology

    Science.gov (United States)

    Romanofsky, Robert R.

    2007-01-01

    While there are a myriad of applications for microwave phase shifters in instrumentation and metrology, power combining, amplifier linearization, and so on, the most prevalent use is in scanning phased-array antennas. And while this market continues to be dominated by military radar and tracking platforms, many commercial applications have emerged in the past decade or so. These new and potential applications span low-Earth-orbit (LEO) communications satellite constellations and collision warning radar, an aspect of the Intelligent Vehicle Highway System or Automated Highway System. In any case, the phase shifters represent a considerable portion of the overall antenna cost, with some estimates approaching 40 percent for receive arrays. Ferrite phase shifters continue to be the workhorse in military-phased arrays, and while there have been advances in thin film ferrite devices, the review of this device technology in the previous edition of this book is still highly relevant. This chapter will focus on three types of phase shifters that have matured in the past decade: GaAs MESFET monolithic microwave integrated circuit (MMIC), micro-electromechanical systems (MEMS), and thin film ferroelectric-based devices. A brief review of some novel devices including thin film ferrite phase shifters and superconducting switches for phase shifter applications will be provided. Finally, the effects of modulo 2 phase shift limitations, phase errors, and transient response on bit error rate degradation will be considered.

  5. Compact, semi-passive beam steering prism array for solar concentrators.

    Science.gov (United States)

    Zheng, Cheng; Li, Qiyuan; Rosengarten, Gary; Hawkes, Evatt; Taylor, Robert A

    2017-05-10

    In order to maximize solar energy utilization in a limited space (e.g., rooftops), solar collectors should track the sun. As an alternative to rotational tracking systems, this paper presents a compact, semi-passive beam steering prism array which has been designed, analyzed, and tested for solar applications. The proposed prism array enables a linear concentrator system to remain stationary so that it can integrate with a variety of different solar concentrators, and which should be particularly useful for systems which require a low profile (namely rooftop-mounted systems). A case study of this prism array working within a specific rooftop solar collector demonstrates that it can boost the average daily optical efficiency of the collector by 32.7% and expand its effective working time from 6 h to 7.33 h. Overall, the proposed design provides an alternative way to "follow" the sun for a wide range of solar thermal and photovoltaic concentrator systems.

  6. A linear polarization converter with near unity efficiency in microwave regime

    Science.gov (United States)

    Xu, Peng; Wang, Shen-Yun; Geyi, Wen

    2017-04-01

    In this paper, we present a linear polarization converter in the reflective mode with near unity conversion efficiency. The converter is designed in an array form on the basis of a pair of orthogonally arranged three-dimensional split-loop resonators sharing a common terminal coaxial port and a continuous metallic ground slab. It converts the linearly polarized incident electromagnetic wave at resonance to its orthogonal counterpart upon the reflection mode. The conversion mechanism is explained by an equivalent circuit model, and the conversion efficiency can be tuned by changing the impedance of the terminal port. Such a scheme of the linear polarization converter has potential applications in microwave communications, remote sensing, and imaging.

  7. Observations of short period seismic scattered waves by small seismic arrays

    Directory of Open Access Journals (Sweden)

    M. Simini

    1997-06-01

    Full Text Available The most recent observations of well correlated seismic phases in the high frequency coda of local earthquakes recorded throughout the world are reported. In particular the main results, obtained on two active volcanoes, Teide and Deception, using small array are described. The ZLC (Zero Lag Cross-correlation method and polarization analysis have been applied to the data in order to distinguish the main phases in the recorded seismograms and their azimuths and apparent velocities. The results obtained at the Teide volcano demonstrate that the uncorrelated part of the seismograms may be produced by multiple scattering from randomly distributed heterogeneity, while the well correlated part, showing SH type polarization or the possible presence of Rayleigh surface waves, may be generated by single scattering by strong scatterers. At the Deception Volcano strong scattering, strongly focused in a precise direction, is deduced from the data. In that case, all the coda radiation is composed of surface waves.

  8. Infrared detectors and focal plane arrays; Proceedings of the Meeting, Orlando, FL, Apr. 18, 19, 1990

    Science.gov (United States)

    Dereniak, Eustace L.; Sampson, Robert E.

    1990-09-01

    The papers contained in this volume provide an overview of recent advances and the current state of developments in the field of infrared detectors and focal plane arrays. Topics discussed include nickel silicide Schottky-barrier detectors for short-wavelength infrared applications; high performance PtSi linear and focal plane arrays; and multispectral band Schottky-barrier IRSSD for remote-sensing applications. Papers are also presented on the performance of an Insi hybrid focal array; characterization of IR focal plane test stations; GaAs CCD readout for engineered bandgap detectors; and fire detection system for aircraft cargo bays.

  9. 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.

  10. Anisotropy of magnetic properties in 2D arrays of permalloy antidots

    Energy Technology Data Exchange (ETDEWEB)

    Kolmychek, I.A., E-mail: irisha@shg.ru [Moscow State University, 119991 GSP-1, Leninskie Gory, Moscow (Russian Federation); Krutyanskiy, V.L.; Gusev, K.S.; Murzina, T.V. [Moscow State University, 119991 GSP-1, Leninskie Gory, Moscow (Russian Federation); Tahir, N.; Kurant, Z.; Maziewski, A. [Department of Physics, University of Bialystok (Poland); Ding, J.; Adeyeye, A.O. [Department of Electrical Computer Engineering, National University of Singapore (Singapore)

    2016-12-15

    Anisotropy of linear and nonlinear magnetooptical (MO) effects in a regular array of Py antidots is studied by means of the MO Kerr effect at the fundamental and second harmonic wavelengths. We have demonstrated that the value of the MO effect, coercivity, and magnetization distribution depend substantially on the azimuthal orientation of the antidots array relatively to the external magnetic field. - Highlights: • The results from the anisotropy of Py antidots are presented. • The hard magnetization axis is oriented along the side of the antidot square lattice. • The value of the saturated LMOKE effect is isotropic. • The maximum of the SHG magnetic contrast was observed along easy axis.

  11. Force sensitive carbon nanotube arrays for biologically inspired airflow sensing

    International Nuclear Information System (INIS)

    Maschmann, Matthew R; Ehlert, Gregory J; Baur, Jeffery W; Dickinson, Ben

    2012-01-01

    The compressive electromechanical response of aligned carbon nanotube (CNT) arrays is evaluated for use as an artificial hair sensor (AHS) transduction element. CNT arrays with heights of 12, 75, and 225 µm are examined. The quasi-static and dynamic sensitivity to force, response time, and signal drift are examined within the range of applied stresses predicted by a mechanical model applicable to the conceptual CNT array-based AHS (0–1 kPa). Each array is highly sensitive to compressive loading, with a maximum observed gauge factor of 114. The arrays demonstrate a repeatable response to dynamic cycling after a break-in period of approximately 50 cycles. Utilizing a four-wire measurement electrode configuration, the change in contact resistance between the array and the electrodes is observed to dominate the electromechanical response of the arrays. The response time of the CNT arrays is of the order of 10 ms. When the arrays are subjected to constant stress, mechanical creep is observed that results in a signal drift that generally diminishes the responsiveness of the arrays, particularly at stress approaching 1 kPa. The results of this study serve as a preliminary proof of concept for utilizing CNT arrays as a transduction mechanism for a proposed artificial hair sensor. Such a low profile and light-weight flow sensor is expected to have application in a number of applications including navigation and state awareness of small air vehicles, similar in function to natural hair cell receptors utilized by insects and bats. (paper)

  12. Force sensitive carbon nanotube arrays for biologically inspired airflow sensing

    Science.gov (United States)

    Maschmann, Matthew R.; Dickinson, Ben; Ehlert, Gregory J.; Baur, Jeffery W.

    2012-09-01

    The compressive electromechanical response of aligned carbon nanotube (CNT) arrays is evaluated for use as an artificial hair sensor (AHS) transduction element. CNT arrays with heights of 12, 75, and 225 µm are examined. The quasi-static and dynamic sensitivity to force, response time, and signal drift are examined within the range of applied stresses predicted by a mechanical model applicable to the conceptual CNT array-based AHS (0-1 kPa). Each array is highly sensitive to compressive loading, with a maximum observed gauge factor of 114. The arrays demonstrate a repeatable response to dynamic cycling after a break-in period of approximately 50 cycles. Utilizing a four-wire measurement electrode configuration, the change in contact resistance between the array and the electrodes is observed to dominate the electromechanical response of the arrays. The response time of the CNT arrays is of the order of 10 ms. When the arrays are subjected to constant stress, mechanical creep is observed that results in a signal drift that generally diminishes the responsiveness of the arrays, particularly at stress approaching 1 kPa. The results of this study serve as a preliminary proof of concept for utilizing CNT arrays as a transduction mechanism for a proposed artificial hair sensor. Such a low profile and light-weight flow sensor is expected to have application in a number of applications including navigation and state awareness of small air vehicles, similar in function to natural hair cell receptors utilized by insects and bats.

  13. Downlink Channel Estimation in Cellular Systems with Antenna Arrays at Base Stations Using Channel Probing with Feedback

    Directory of Open Access Journals (Sweden)

    Biguesh Mehrzad

    2004-01-01

    Full Text Available In mobile communication systems with multisensor antennas at base stations, downlink channel estimation plays a key role because accurate channel estimates are needed for transmit beamforming. One efficient approach to this problem is channel probing with feedback. In this method, the base station array transmits probing (training signals. The channel is then estimated from feedback reports provided by the users. This paper studies the performance of the channel probing method with feedback using a multisensor base station antenna array and single-sensor users. The least squares (LS, linear minimum mean square error (LMMSE, and a new scaled LS (SLS approaches to the channel estimation are studied. Optimal choice of probing signals is investigated for each of these techniques and their channel estimation performances are analyzed. In the case of multiple LS channel estimates, the best linear unbiased estimation (BLUE scheme for their linear combining is developed and studied.

  14. Ti/TiO 2 nanotube array electrode as a new sensor to ...

    Indian Academy of Sciences (India)

    The Ti/TiO2 nanotube array (Ti-NTA) electrode was prepared by anodizing of the Ti foil ... and the pH=3.0 and =1.0 V (vs. reference electrode) were determined as the ... It was found that the photocurrent of EG was linearly dependent on the ...

  15. "Towards a Future Linear Collider" and "The Linear Collider Studies at CERN"

    CERN Document Server

    CERN. Geneva

    2010-01-01

    During the week 18-22 October, more than 400 physicists will meet at CERN and in the CICG (International Conference Centre Geneva) to review the global progress towards a future linear collider. The 2010 International Workshop on Linear Colliders will study the physics, detectors and accelerator complex of a linear collider covering both the CLIC and ILC options. Among the topics presented and discussed will be the progress towards the CLIC Conceptual Design Report in 2011, the ILC Technical Design Report in 2012, physics and detector studies linked to these reports, and an increasing numbers of common working group activities. The seminar will give an overview of these topics and also CERN’s linear collider studies, focusing on current activities and initial plans for the period 2011-16. n.b: The Council Chamber is also reserved for this colloquium with a live transmission from the Main Auditorium.

  16. Modified linear predictive coding approach for moving target tracking by Doppler radar

    Science.gov (United States)

    Ding, Yipeng; Lin, Xiaoyi; Sun, Ke-Hui; Xu, Xue-Mei; Liu, Xi-Yao

    2016-07-01

    Doppler radar is a cost-effective tool for moving target tracking, which can support a large range of civilian and military applications. A modified linear predictive coding (LPC) approach is proposed to increase the target localization accuracy of the Doppler radar. Based on the time-frequency analysis of the received echo, the proposed approach first real-time estimates the noise statistical parameters and constructs an adaptive filter to intelligently suppress the noise interference. Then, a linear predictive model is applied to extend the available data, which can help improve the resolution of the target localization result. Compared with the traditional LPC method, which empirically decides the extension data length, the proposed approach develops an error array to evaluate the prediction accuracy and thus, adjust the optimum extension data length intelligently. Finally, the prediction error array is superimposed with the predictor output to correct the prediction error. A series of experiments are conducted to illustrate the validity and performance of the proposed techniques.

  17. Controlling periodic ripple microstructure formation on 4H-SiC crystal with three time-delayed femtosecond laser beams of different linear polarizations.

    Science.gov (United States)

    He, Wanlin; Yang, Jianjun; Guo, Chunlei

    2017-03-06

    The control of laser-induced periodic ripple microstructures on 4H-SiC crystal surface is studied using temporally delayed collinear three femtosecond laser pulse trains linearly polarized in different directions. The ripple orientation appears to develop independent of the individual laser polarizations and exhibits non-monotonical change with variable time delays, whose variation tendency is also affected by the polarization intersection angles. Remarkably, the ripple period is observed to transfer from high- to low-spatial-frequency regions, accompanied by distinctly improved morphological uniformity and clearness. The results are satisfactorily interpreted based on a physical model of the surface wave excitation on a transient index metasurface, which is confirmed by further experiments. Our investigations indicate that transient noneqilibrium dynamics of the material surface provides an effective way to manipulate the laser-induced microstructures.

  18. Validity of purchasing power parity for selected Latin American countries: Linear and non-linear unit root tests

    Directory of Open Access Journals (Sweden)

    Claudio Roberto Fóffano Vasconcelos

    2016-01-01

    Full Text Available The aim of this study is to examine empirically the validity of PPP in the context of unit root tests based on linear and non-linear models of the real effective exchange rate of Argentina, Brazil, Chile, Colombia, Mexico, Peru and Venezuela. For this purpose, we apply the Harvey et al. (2008 linearity test and the non-linear unit root test (Kruse, 2011. The results show that the series with linear characteristics are Argentina, Brazil, Chile, Colombia and Peru and those with non-linear characteristics are Mexico and Venezuela. The linear unit root tests indicate that the real effective exchange rate is stationary for Chile and Peru, and the non-linear unit root tests evidence that Mexico is stationary. In the period analyzed, the results show support for the validity of PPP in only three of the seven countries.

  19. Josephson junctions array resonators

    Energy Technology Data Exchange (ETDEWEB)

    Gargiulo, Oscar; Muppalla, Phani; Mirzaei, Iman; Kirchmair, Gerhard [Institute for Quantum Optics and Quantum Information, Innsbruck (Austria)

    2016-07-01

    We present an experimental analysis of the self- and cross-Kerr effect of extended plasma resonances in Josephson junction chains. The chain consists of 1600 individual junctions and we can measure quality factors in excess of 10000. The Kerr effect manifests itself as a frequency shift that depends linearly on the number of photons in a resonant mode. By changing the input power we are able to measure this frequency shift on a single mode (self-kerr). By changing the input power on another mode while measuring the same one, we are able to evaluate the cross-kerr effect. We can measure the cross-Kerr effect by probing the resonance frequency of one mode while exciting another mode of the array with a microwave drive.

  20. Periodically structured Si pillars for high-performing heterojunction photodetectors

    Science.gov (United States)

    Melvin David Kumar, M.; Yun, Ju-Hyung; Kim, Joondong

    2015-03-01

    A periodical array of silicon (Si) micro pillar structures was fabricated on Si substrates using PR etching process. Indium tin oxide (ITO) layer of 80 nm thickness was deposited over patterned Si substrates so as to make ITO/n-Si heterojunction devices. The influences of width and period of pillars on the optical and electrical properties of prepared devices were investigated. The surface morphology of the Si substrates revealed the uniform array of pillar structures. The 5/10 (width/period) Si pillar pattern reduced the optical reflectance to 6.5% from 17% which is of 5/7 pillar pattern. The current rectifying ratio was found higher for the device in which the pillars are situated in optimum periods. At both visible (600 nm) and near infrared (900 nm) range of wavelengths, the 5/7 and 5/10 pillar patterned device exhibited the better photoresponses which are suitable for making advanced photodetectors. This highly transmittance and photoresponsive pillar patterned Si substrates with an ITO layer would be a promising device for various photoelectric applications.

  1. Numerical simulation of crosstalk in reduced pitch HgCdTe photon-trapping structure pixel arrays.

    Science.gov (United States)

    Schuster, Jonathan; Bellotti, Enrico

    2013-06-17

    We have investigated crosstalk in HgCdTe photovoltaic pixel arrays employing a photon trapping (PT) structure realized with a periodic array of pillars intended to provide broadband operation. We have found that, compared to non-PT pixel arrays with similar geometry, the array employing the PT structure has a slightly higher optical crosstalk. However, when the total crosstalk is evaluated, the presence of the PT region drastically reduces the total crosstalk; making the use of the PT structure not only useful to obtain broadband operation, but also desirable for reducing crosstalk in small pitch detector arrays.

  2. Seasonal Variations in Resistivity at a Police Forensic Site and the Effectiveness of Unconventional Array Types

    Science.gov (United States)

    Edwards, S.; Bank, C. G.

    2016-12-01

    Geophysical studies involving the detection of buried organic material can be affected by the passage of time and environmental changes such as temperature and, in more importantly, water content in the ground. These effects can be of particular concern for police forensic investigations. This study involved conducting multiple resistivity surveys across 4 months to determine how time and environmental variations affected the detection of porcine carcasses buried four years previous at a provincial police training and research site. Our research also explored survey results of non-conventional grid and square arrays versus traditional linear arrays. The study site is located in Bolton, Ontario, and measures 16 m by 30 m. It contains 18 graves plus other buried objects. Studies were conducted approximately every other week. The resistivity lines used Wenner arrays of 24 m (0.5 m electrode spacing) and 48 m (1 m spacing) in length. Environmental data was obtained from Environment Canada and through simple observations. Preliminary findings indicated that time and environmental changes affected the detection of the porcine bodies by either being too dry and having too high a resistivity to survey effectively, or too wet and having the site flushed with water making the surrounding ground similar in resistivity to the bodies. Future research is needed to further explore how best to minimize environmental changes from resistivity results to enable reliable detection of buried organic material such as human remains In regard to array configurations, the square array in particular shows promise in that it can be set up and executed in less time than running several linear arrays over the same area. The application of such unconventional arrays to police forensic work may prove valuable if the area of interest is off-limits for resistivity surveys due to physical obstructions.

  3. BLAS- BASIC LINEAR ALGEBRA SUBPROGRAMS

    Science.gov (United States)

    Krogh, F. T.

    1994-01-01

    The Basic Linear Algebra Subprogram (BLAS) library is a collection of FORTRAN callable routines for employing standard techniques in performing the basic operations of numerical linear algebra. The BLAS library was developed to provide a portable and efficient source of basic operations for designers of programs involving linear algebraic computations. The subprograms available in the library cover the operations of dot product, multiplication of a scalar and a vector, vector plus a scalar times a vector, Givens transformation, modified Givens transformation, copy, swap, Euclidean norm, sum of magnitudes, and location of the largest magnitude element. Since these subprograms are to be used in an ANSI FORTRAN context, the cases of single precision, double precision, and complex data are provided for. All of the subprograms have been thoroughly tested and produce consistent results even when transported from machine to machine. BLAS contains Assembler versions and FORTRAN test code for any of the following compilers: Lahey F77L, Microsoft FORTRAN, or IBM Professional FORTRAN. It requires the Microsoft Macro Assembler and a math co-processor. The PC implementation allows individual arrays of over 64K. The BLAS library was developed in 1979. The PC version was made available in 1986 and updated in 1988.

  4. Periodic orbits around areostationary points in the Martian gravity field

    International Nuclear Information System (INIS)

    Liu Xiaodong; Baoyin Hexi; Ma Xingrui

    2012-01-01

    This study investigates the problem of areostationary orbits around Mars in three-dimensional space. Areostationary orbits are expected to be used to establish a future telecommunication network for the exploration of Mars. However, no artificial satellites have been placed in these orbits thus far. The characteristics of the Martian gravity field are presented, and areostationary points and their linear stability are calculated. By taking linearized solutions in the planar case as the initial guesses and utilizing the Levenberg-Marquardt method, families of periodic orbits around areostationary points are shown to exist. Short-period orbits and long-period orbits are found around linearly stable areostationary points, but only short-period orbits are found around unstable areostationary points. Vertical periodic orbits around both linearly stable and unstable areostationary points are also examined. Satellites in these periodic orbits could depart from areostationary points by a few degrees in longitude, which would facilitate observation of the Martian topography. Based on the eigenvalues of the monodromy matrix, the evolution of the stability index of periodic orbits is determined. Finally, heteroclinic orbits connecting the two unstable areostationary points are found, providing the possibility for orbital transfer with minimal energy consumption.

  5. Status of the development of the brazilian decimetric array

    Science.gov (United States)

    Sawant, H. S.; Neri, J. A. C. F.; Cecatto, J. R.; Fernandes, F. C. R.; Bethi, N. K.; Viola, F. E. C.; Andrade, M. C.; Alonso, E. M. B.; Felipini, N. S.; Cassiano, A. B.; Madsen, F. R. H.; Boas, J. W. S.; Rosa, R. R.; Stephany, S.; Faria, C.; Subramanian, K. R.; Ramesh, R.; Sundararajan, M. S.; Sankararaman, M. R.; Ananthkrishnan, S.; Swarup, G.; Saito, J. H.; Moron, C. E.; Mascarenhas, N.; Botti, L. C. L.; Lüdke, E.

    2003-08-01

    Brazil is now among the 7 countries that will dominate the technology of interferometry for astrophysical high spatial and time resolution observation in microwave band. The Prototype of Brazilian Decimetric Array (PBDA), unique in Latin America, has been successfully developed. A spin off for this technical development with high pointing accuracy will have application in satellite tracking, monitoring of the frequency interference and other purposes. This array operates in the frequency range of (1.2 - 1.7) GHz. Mechanical alt-azimuth mount for parabolic dishes of 4 or 5 meter diameter mesh type antennas have been developed locally. Alt-azimuth tracking systems hardware/software to track 5 antennas simultaneously has been integrated by Inteltek Automation Company of Pune, India. Tracking systems hardware panels mounting and cables routing were done locally. Crossed log-periodic dual polarized feeders were developed, with 50 ohm impedance operating in the frequency range of (1.2 - 1.7) GHz and they were tested in anechoic chamber to measure the VSWR (Voltage Standing Wave Ratio), impedances and cross-talk between the two linear polarization. Low noise pre-amplifiers operating in the frequency range of (1.2 - 1.7) GHz mounted at the back of the feeder were developed and tested. The receivers based on high stability Phase Locked Oscillator (PLO) have been developed with final video output bandwidth of 2.5 MHz. The digital correlator for prototype has been developed and interfaced to PBDA analogue system. Tracking and pointing accuracies for solar non-solar observations, the fringe rates of 10 baselines and also the observation of a weak solar flare will be presented.

  6. 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.

  7. Periodic refractive index modifications inscribed in polymer optical fibre by focussed IR femtosecond pulses

    DEFF Research Database (Denmark)

    Stecher, Matthias; Williams, Robert J.; Bang, Ole

    Focussed femtosecond laser pulses were used to inscribe a periodic array of modifications in the core of a polymer optical fibre. Structural and refractive-index modifications have been observed at different pulse energies using DIC microscopy.......Focussed femtosecond laser pulses were used to inscribe a periodic array of modifications in the core of a polymer optical fibre. Structural and refractive-index modifications have been observed at different pulse energies using DIC microscopy....

  8. A DP based scheme for real-time reconfiguration of solar cell arrays exposed to dynamic changing inhomogeneous illuminations

    DEFF Research Database (Denmark)

    Shi, Liping; Brehm, Robert

    2016-01-01

    The overall energy conversion efficiency of solar cell arrays is highly effected by partial shading effects. Especially for solar panel arrays installed in environments which are exposed to inhomogeneous dynamic changing illuminations such as on roof tops of electrical vehicles the overall system...... efficiency is drastically reduced. Dynamic real-time reconfiguration of the solar panel array can reduce effects on the output efficiency due to partial shading. This results in a maximized power output of the panel array when exposed to dynamic changing illuminations. The optimal array configuration...... with respect to shading patterns can be stated as a combinatorial optimization problem and this paper proposes a dynamic programming (DP) based algorithm which finds the optimal feasible solution to reconfigure the solar panel array for maximum efficiency in real-time with linear time complexity. It is shown...

  9. Frequency selective surfaces integrated with phased array antennas

    NARCIS (Netherlands)

    Monni, S.

    2005-01-01

    Frequency Selective Surfaces (FSS's) are periodic arrays of patches and/or slots etched on a metal plate, having frequency and angular ??ltering properties. The FSS response to an excitation (for example a plane wave) is characterized in terms of its re ection and transmission coe??cient, and

  10. 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.

  11. 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.

  12. First light from a kilometer-baseline Scintillation Auroral GPS Array.

    Science.gov (United States)

    Datta-Barua, S; Su, Y; Deshpande, K; Miladinovich, D; Bust, G S; Hampton, D; Crowley, G

    2015-05-28

    We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100-1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies. A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed.

  13. Infrared focal plane array producibility and related materials; Proceedings of the Meeting, Orlando, FL, Apr. 20, 21, 1992

    Science.gov (United States)

    Balcerak, Ray; Pellegrini, Paul W.; Scribner, Dean A.

    The present conference discusses the commercial diversification of the U.S. IR detector industry's commercial diversification, HgCdTe focal-plane array (FPAs) manufacture, LPE of (Hg,Cd)Te FPAs, uncooled IR FPA detector producibility, a high performance staring IR camera, and novel technologies for FPA dewars. Also discussed are hybridizing FPAs, cryoprober test development, HgCdTe on Si for monolithic focal plane arrays, popcorn noise in linear InGaAs detector arrays, and the use of narrowband laser speckle for MTF characterization of CCDs. (No individual items are abstracted in this volume)

  14. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    Science.gov (United States)

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  15. Insertion of linear 8.4 μm diameter 16 channel carbon fiber electrode arrays for single unit recordings

    Science.gov (United States)

    Patel, Paras R.; Na, Kyounghwan; Zhang, Huanan; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Yoon, Euisik; Chestek, Cynthia A.

    2016-01-01

    Objective Single carbon fiber electrodes (d=8.4 μm) insulated with parylene-c and functionalized with PEDOT:pTS have been shown to record single unit activity but manual implantation of these devices with forceps can be difficult. Without an improvement in the insertion method any increase in the channel count by fabricating carbon fiber arrays would be impractical. In this study, we utilize a water soluble coating and structural backbones that allow us to create, implant, and record from fully functionalized arrays of carbon fibers with ~150 μm pitch. Approach Two approaches were tested for the insertion of carbon fiber arrays. The first method used a PEG coating that temporarily stiffened the fibers while leaving a small portion at the tip exposed. The small exposed portion (500 μm – 1 mm) readily penetrated the brain allowing for an insertion that did not require the handling of each fiber by forceps. The second method involved the fabrication of silicon support structures with individual shanks spaced 150 μm apart. Each shank consisted of a small groove that held an individual carbon fiber. Main results Our results showed that the PEG coating allowed for the chronic implantation of carbon fiber arrays in 5 rats with unit activity detected at 31 days post-implant. The silicon support structures recorded single unit activity in 3 acute rat surgeries. In one of those surgeries a stacked device with 3 layers of silicon support structures and carbon fibers was built and shown to readily insert into the brain with unit activity on select sites. Significance From these studies we have found that carbon fibers spaced at ~150 μm readily insert into the brain. This greatly increases the recording density of chronic neural probes and paves the way for even higher density devices that have a minimal scarring response. PMID:26035638

  16. Screening of Carotenoids in Tomato Fruits by Using Liquid Chromatography with Diode Array-Linear Ion Trap Mass Spectrometry Detection.

    Science.gov (United States)

    Gentili, Alessandra; Caretti, Fulvia; Ventura, Salvatore; Pérez-Fernández, Virginia; Venditti, Alessandro; Curini, Roberta

    2015-08-26

    This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

  17. Re-examining the risk–return relationship in Europe: Linear or non-linear trade-off?

    OpenAIRE

    Salvador, Enrique; Floros, Christos; Arago, Vicent

    2014-01-01

    This paper analyzes the risk–return trade-off in Europe using recent data from 11 European stock markets. After relaxing the linear assumptions in the risk–return relationship by introducing a new approach that considers the current state of the market, we obtain significant evidence for a positive risk–return trade-off for low volatility states. However, this finding is reduced or even non-significant during periods of high volatility. Maintaining the linear assumption over the risk–return t...

  18. Misfit-guided self-organization of anticorrelated Ge quantum dot arrays on Si nanowires.

    Science.gov (United States)

    Kwon, Soonshin; Chen, Zack C Y; Kim, Ji-Hun; Xiang, Jie

    2012-09-12

    Misfit-strain guided growth of periodic quantum dot (QD) arrays in planar thin film epitaxy has been a popular nanostructure fabrication method. Engineering misfit-guided QD growth on a nanoscale substrate such as the small curvature surface of a nanowire represents a new approach to self-organized nanostructure preparation. Perhaps more profoundly, the periodic stress underlying each QD and the resulting modulation of electro-optical properties inside the nanowire backbone promise to provide a new platform for novel mechano-electronic, thermoelectronic, and optoelectronic devices. Herein, we report a first experimental demonstration of self-organized and self-limited growth of coherent, periodic Ge QDs on a one-dimensional Si nanowire substrate. Systematic characterizations reveal several distinctively different modes of Ge QD ordering on the Si nanowire substrate depending on the core diameter. In particular, Ge QD arrays on Si nanowires of around 20 nm diameter predominantly exhibit an anticorrelated pattern whose wavelength agrees with theoretical predictions. The correlated pattern can be attributed to propagation and correlation of misfit strain across the diameter of the thin nanowire substrate. The QD array growth is self-limited as the wavelength of the QDs remains unchanged even after prolonged Ge deposition. Furthermore, we demonstrate a direct kinetic transformation from a uniform Ge shell layer to discrete QD arrays by a postgrowth annealing process.

  19. Characterization of cable gun plasma with a charge collector array

    International Nuclear Information System (INIS)

    Chen Yulan; Zeng Zhengzhong; Sun Fengju; Kuai Bin; Qiu Aici; Yin Jiahui; Cong Peitian; Liang Tianxue

    2003-01-01

    The density, drift velocity and reproducibility of the plasma produced by a cable plasma gun array have been measured with a charge collector array. The plasma is used to prefill a coaxial plasma-opening switch with a conducting time approaching 0.4 μs. The reproducibility of the plasma source in subsequent shots is better than 5%. Near the gun nozzle and the opposite electrode, the plasma density amounts to 10 15 cm -3 , which is 2 times to 3 times that in the gap between the two coaxial electrodes. A plasma drift velocity of about 2.4 cm/μs is observed from the time of flight of the charged particles. Both plasma density and drift velocity increase almost linearly with the rise in charge voltage

  20. Thermal analysis for folded solar array of spacecraft in orbit

    International Nuclear Information System (INIS)

    Yang, W.H.; Cheng, H.E.; Cai, A.

    2004-01-01

    The combined radiation-conduction heat transfer in folded solar array was considered as a three-dimensional anisotropic conduction without inner heat source. The three-dimensional equivalent conductivity in cell plate were obtained. The especially discrete equation coefficients of the nodes on the surfaces of adjacent cell plates were deduced by utilizing the simplified radiation network among the two adjacent cell plate surfaces and the deep cold space. All the thermal influence factors on the temperature response of the folded solar array were considered carefully. SIP method was used to solve the discrete equation. By comparing the calculation results under three cases, the temperature response and the maximum average difference of the folded solar array was obtained during the period of throw-radome of the launch vehicle and spread of the folded solar array. The obtained result is a valuable reference for the selection of the launch time of the spacecraft