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Sample records for direction-of-arrival doa estimation

  1. Spiral-shaped piezoelectric sensors for Lamb waves direction of arrival (DoA) estimation

    Science.gov (United States)

    De Marchi, L.; Testoni, N.; Marzani, A.

    2018-04-01

    A novel strategy to design piezoelectric sensors suited for direction of arrival (DoA) estimation of incoming Lamb waves is presented in this work. The designed sensor is composed by two piezoelectric patches (P1, P2) bonded on the structure to be inspected. In particular, by exploiting the Radon transform, the proposed procedure computes the shape of P2 given the shape of P1 so that the difference in time of arrival (DToA) of the Lamb waves at the two patches is linearly related to the DoA while being agnostic of the waveguide dispersion curves. With a dedicated processing procedure, the waveforms acquired from the two electrodes and digitized can be used to retrieve the DoA information. Numerical and experimental results show that DoA estimation performed by means of the proposed shaped transducers is extremely robust.

  2. The Real-Valued Sparse Direction of Arrival (DOA Estimation Based on the Khatri-Rao Product

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2016-05-01

    Full Text Available There is a problem that complex operation which leads to a heavy calculation burden is required when the direction of arrival (DOA of a sparse signal is estimated by using the array covariance matrix. The solution of the multiple measurement vectors (MMV model is difficult. In this paper, a real-valued sparse DOA estimation algorithm based on the Khatri-Rao (KR product called the L1-RVSKR is proposed. The proposed algorithm is based on the sparse representation of the array covariance matrix. The array covariance matrix is transformed to a real-valued matrix via a unitary transformation so that a real-valued sparse model is achieved. The real-valued sparse model is vectorized for transforming to a single measurement vector (SMV model, and a new virtual overcomplete dictionary is constructed according to the KR product’s property. Finally, the sparse DOA estimation is solved by utilizing the idea of a sparse representation of array covariance vectors (SRACV. The simulation results demonstrate the superior performance and the low computational complexity of the proposed algorithm.

  3. 2-D unitary ESPRIT-like direction-of-arrival (DOA) estimation for coherent signals with a uniform rectangular array.

    Science.gov (United States)

    Ren, Shiwei; Ma, Xiaochuan; Yan, Shefeng; Hao, Chengpeng

    2013-03-28

    A unitary transformation-based algorithm is proposed for two-dimensional (2-D) direction-of-arrival (DOA) estimation of coherent signals. The problem is solved by reorganizing the covariance matrix into a block Hankel one for decorrelation first and then reconstructing a new matrix to facilitate the unitary transformation. By multiplying unitary matrices, eigenvalue decomposition and singular value decomposition are both transformed into real-valued, so that the computational complexity can be reduced significantly. In addition, a fast and computationally attractive realization of the 2-D unitary transformation is given by making a Kronecker product of the 1-D matrices. Compared with the existing 2-D algorithms, our scheme is more efficient in computation and less restrictive on the array geometry. The processing of the received data matrix before unitary transformation combines the estimation of signal parameters via rotational invariance techniques (ESPRIT)-Like method and the forward-backward averaging, which can decorrelate the impinging signalsmore thoroughly. Simulation results and computational order analysis are presented to verify the validity and effectiveness of the proposed algorithm.

  4. Narrowband direction of arrival estimation for antenna arrays

    CERN Document Server

    Foutz, Jeffrey

    2008-01-01

    This book provides an introduction to narrowband array signal processing, classical and subspace-based direction of arrival (DOA) estimation with an extensive discussion on adaptive direction of arrival algorithms. The book begins with a presentation of the basic theory, equations, and data models of narrowband arrays. It then discusses basic beamforming methods and describes how they relate to DOA estimation. Several of the most common classical and subspace-based direction of arrival methods are discussed. The book concludes with an introduction to subspace tracking and shows how subspace tr

  5. Direction of arrival estimation based on information geometry

    NARCIS (Netherlands)

    Coutiño Minguez, M.A.; Pribic, R; Leus, G.J.T.; Dong, Min; Zheng, Thomas Fang

    2016-01-01

    In this paper, a new direction of arrival (DOA) estimation approach is devised using concepts from information geometry (IG). The proposed method uses geodesic distances in the statistical manifold of probability distributions parametrized by their covariance matrix to estimate the direction of

  6. Estimating Radar Velocity using Direction of Arrival Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Horndt, Volker [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States); Bickel, Douglas Lloyd [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naething, Richard M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    Direction of Arrival (DOA) measurements, as with a monopulse antenna, can be compared against Doppler measurements in a Synthetic Aperture Radar ( SAR ) image to determine an aircraft's forward velocity as well as its crab angle, to assist the aircraft's navigation as well as improving high - performance SAR image formation and spatial calibration.

  7. The effects of single bit quantization on direction of arrival estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2016-01-01

    Phased arrays can be used to estimate the direction-of-arrival (DOA) of UHF RFID tags. To save on energy consumption and hardware costs, in this paper we explore the possibility of using single bit analog-to-digital converters for our phased array setup. This setup consists of an off-the-shelf

  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. Blind Direction-of-Arrival Estimation with Uniform Circular Array in Presence of Mutual Coupling

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    Song Liu

    2016-01-01

    Full Text Available A blind direction-of-arrival (DOA estimation algorithm based on the estimation of signal parameters via rotational invariance techniques (ESPRIT is proposed for a uniform circular array (UCA when strong electromagnetic mutual coupling is present. First, an updated UCA model with mutual coupling in a discrete Fourier transform (DFT beam space is deduced, and the new manifold matrix is equal to the product of a centrosymmetric diagonal matrix and a Vandermonde-structure matrix. Then we carry out blind DOA estimation through a modified ESPRIT method, thus avoiding the need for spatial angular searching. In addition, two mutual coupling parameter estimation methods are presented after the DOAs have been estimated. Simulation results show that the new algorithm is reliable and effective especially for closely spaced signals.

  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. Direction-of-Arrival Estimation for Coherent Sources via Sparse Bayesian Learning

    Directory of Open Access Journals (Sweden)

    Zhang-Meng Liu

    2014-01-01

    Full Text Available A spatial filtering-based relevance vector machine (RVM is proposed in this paper to separate coherent sources and estimate their directions-of-arrival (DOA, with the filter parameters and DOA estimates initialized and refined via sparse Bayesian learning. The RVM is used to exploit the spatial sparsity of the incident signals and gain improved adaptability to much demanding scenarios, such as low signal-to-noise ratio (SNR, limited snapshots, and spatially adjacent sources, and the spatial filters are introduced to enhance global convergence of the original RVM in the case of coherent sources. The proposed method adapts to arbitrary array geometry, and simulation results show that it surpasses the existing methods in DOA estimation performance.

  12. A Robust Real Time Direction-of-Arrival Estimation Method for Sequential Movement Events of Vehicles.

    Science.gov (United States)

    Liu, Huawei; Li, Baoqing; Yuan, Xiaobing; Zhou, Qianwei; Huang, Jingchang

    2018-03-27

    Parameters estimation of sequential movement events of vehicles is facing the challenges of noise interferences and the demands of portable implementation. In this paper, we propose a robust direction-of-arrival (DOA) estimation method for the sequential movement events of vehicles based on a small Micro-Electro-Mechanical System (MEMS) microphone array system. Inspired by the incoherent signal-subspace method (ISM), the method that is proposed in this work employs multiple sub-bands, which are selected from the wideband signals with high magnitude-squared coherence to track moving vehicles in the presence of wind noise. The field test results demonstrate that the proposed method has a better performance in emulating the DOA of a moving vehicle even in the case of severe wind interference than the narrowband multiple signal classification (MUSIC) method, the sub-band DOA estimation method, and the classical two-sided correlation transformation (TCT) method.

  13. Novel Diagonal Reloading Based Direction of Arrival Estimation in Unknown Non-Uniform Noise

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    Hao Zhou

    2018-01-01

    Full Text Available Nested array can expand the degrees of freedom (DOF from difference coarray perspective, but suffering from the performance degradation of direction of arrival (DOA estimation in unknown non-uniform noise. In this paper, a novel diagonal reloading (DR based DOA estimation algorithm is proposed using a recently developed nested MIMO array. The elements in the main diagonal of the sample covariance matrix are eliminated; next the smallest MN-K eigenvalues of the revised matrix are obtained and averaged to estimate the sum value of the signal power. Further the estimated sum value is filled into the main diagonal of the revised matrix for estimating the signal covariance matrix. In this case, the negative effect of noise is eliminated without losing the useful information of the signal matrix. Besides, the degrees of freedom are expanded obviously, resulting in the performance improvement. Several simulations are conducted to demonstrate the effectiveness of the proposed algorithm.

  14. Direction of Arrival Estimation with a Novel Single-Port Smart Antenna

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    Chen Sun

    2004-08-01

    Full Text Available A novel direction of arrival (DOA estimation technique that uses the conventional multiple-signal classification (MUSIC algorithm with periodic signals is applied to a single-port smart antenna. Results show that the proposed method gives a high-resolution (1 degree DOA estimation in an uncorrelated signal environment. The novelty lies in that the MUSIC algorithm is applied to a simplified antenna configuration. Only 1 analogue-to-digital converter (ADC is used in this antenna, which features low power consumption, low cost, and ease of fabrication. Modifications to the conventional MUSIC algorithm do not bring much additional complexity. The proposed technique is also free from the negative influence by the mutual coupling among antenna elements. Therefore, it offers an economical way to extensively implement smart antennas into the existing wireless mobile communications systems, especially at the power consumption limited mobile terminals such as laptops in wireless networks.

  15. Experimental Results for Direction of Arrival Estimation with a Single Acoustic Vector Sensor in Shallow Water

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    Alper Bereketli

    2015-01-01

    Full Text Available We study the performances of several computationally efficient and simple techniques for estimating direction of arrival (DOA of an underwater acoustic source using a single acoustic vector sensor (AVS in shallow water. Underwater AVS is a compact device, which consists of one hydrophone and three accelerometers in a packaged form, measuring scalar pressure and three-dimensional acceleration simultaneously at a single position. A very controlled experimental setup is prepared to test how well-known techniques, namely, arctan-based, intensity-based, time domain beamforming, and frequency domain beamforming methods, perform in estimating DOA of a source in different circumstances. Experimental results reveal that for almost all cases beamforming techniques perform best. Moreover, arctan-based method, which is the simplest of all, provides satisfactory results for practical purposes.

  16. Direction-of-Arrival Estimation Based on Sparse Recovery with Second-Order Statistics

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    H. Chen

    2015-04-01

    Full Text Available Traditional direction-of-arrival (DOA estimation techniques perform Nyquist-rate sampling of the received signals and as a result they require high storage. To reduce sampling ratio, we introduce level-crossing (LC sampling which captures samples whenever the signal crosses predetermined reference levels, and the LC-based analog-to-digital converter (LC ADC has been shown to efficiently sample certain classes of signals. In this paper, we focus on the DOA estimation problem by using second-order statistics based on the LC samplings recording on one sensor, along with the synchronous samplings of the another sensors, a sparse angle space scenario can be found by solving an $ell_1$ minimization problem, giving the number of sources and their DOA's. The experimental results show that our proposed method, when compared with some existing norm-based constrained optimization compressive sensing (CS algorithms, as well as subspace method, improves the DOA estimation performance, while using less samples when compared with Nyquist-rate sampling and reducing sensor activity especially for long time silence signal.

  17. Employing beam-forming for estimating the direction of arrival in a multi-path propagation environment

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    M. Bresch

    2005-01-01

    Full Text Available Due to recent researches on traffic accidents with vulnerable road users (VRUs, several measures revealed a great opportunity of reduction. However, all measures applied so far failed to reduce the number of traffic accidents if there is no line-of-sight. Therefore, a transponder signal is utilized to make the VRU visible. The motor vehicle carries a mobile receiver for VRU detection and location. The receiver employs digital beam-forming for estimating the direction of arrival (DOA with an antenna array for RF ISM band. A sequence of DOA estimations is used for location and motion estimation purposes.

  18. Sparse DOA estimation with polynomial rooting

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Fernandez Grande, Efren

    2015-01-01

    Direction-of-arrival (DOA) estimation involves the localization of a few sources from a limited number of observations on an array of sensors. Thus, DOA estimation can be formulated as a sparse signal reconstruction problem and solved efficiently with compressive sensing (CS) to achieve highresol......Direction-of-arrival (DOA) estimation involves the localization of a few sources from a limited number of observations on an array of sensors. Thus, DOA estimation can be formulated as a sparse signal reconstruction problem and solved efficiently with compressive sensing (CS) to achieve...... highresolution imaging. Utilizing the dual optimal variables of the CS optimization problem, it is shown with Monte Carlo simulations that the DOAs are accurately reconstructed through polynomial rooting (Root-CS). Polynomial rooting is known to improve the resolution in several other DOA estimation methods...

  19. Estimation of direction of arrival of a moving target using subspace based approaches

    Science.gov (United States)

    Ghosh, Ripul; Das, Utpal; Akula, Aparna; Kumar, Satish; Sardana, H. K.

    2016-05-01

    In this work, array processing techniques based on subspace decomposition of signal have been evaluated for estimation of direction of arrival of moving targets using acoustic signatures. Three subspace based approaches - Incoherent Wideband Multiple Signal Classification (IWM), Least Square-Estimation of Signal Parameters via Rotation Invariance Techniques (LS-ESPRIT) and Total Least Square- ESPIRIT (TLS-ESPRIT) are considered. Their performance is compared with conventional time delay estimation (TDE) approaches such as Generalized Cross Correlation (GCC) and Average Square Difference Function (ASDF). Performance evaluation has been conducted on experimentally generated data consisting of acoustic signatures of four different types of civilian vehicles moving in defined geometrical trajectories. Mean absolute error and standard deviation of the DOA estimates w.r.t. ground truth are used as performance evaluation metrics. Lower statistical values of mean error confirm the superiority of subspace based approaches over TDE based techniques. Amongst the compared methods, LS-ESPRIT indicated better performance.

  20. A fast and automatically paired 2-D direction-of-arrival estimation with and without estimating the mutual coupling coefficients

    Science.gov (United States)

    Filik, Tansu; Tuncer, T. Engin

    2010-06-01

    A new technique is proposed for the solution of pairing problem which is observed when fast algorithms are used for two-dimensional (2-D) direction-of-arrival (DOA) estimation. Proposed method is integrated with array interpolation for efficient use of antenna elements. Two virtual arrays are generated which are positioned accordingly with respect to the real array. ESPRIT algorithm is used by employing both the real and virtual arrays. The eigenvalues of the rotational transformation matrix have the angle information at both magnitude and phase which allows the estimation of azimuth and elevation angles by using closed-form expressions. This idea is used to obtain the paired interpolated ESPRIT algorithm which can be applied for arbitrary arrays when there is no mutual coupling. When there is mutual coupling, two approaches are proposed in order to obtain 2-D paired DOA estimates. These blind methods can be applied for the array geometries which have mutual coupling matrices with a Toeplitz structure. The first approach finds the 2-D paired DOA angles without estimating the mutual coupling coefficients. The second approach estimates the coupling coefficients and iteratively improves both the coupling coefficients and the DOA estimates. It is shown that the proposed techniques solve the pairing problem for uniform circular arrays and effectively estimate the DOA angles in case of unknown mutual coupling.

  1. Reduced-Complexity Direction of Arrival Estimation Using Real-Valued Computation with Arbitrary Array Configurations

    Directory of Open Access Journals (Sweden)

    Feng-Gang Yan

    2018-01-01

    Full Text Available A low-complexity algorithm is presented to dramatically reduce the complexity of the multiple signal classification (MUSIC algorithm for direction of arrival (DOA estimation, in which both tasks of eigenvalue decomposition (EVD and spectral search are implemented with efficient real-valued computations, leading to about 75% complexity reduction as compared to the standard MUSIC. Furthermore, the proposed technique has no dependence on array configurations and is hence suitable for arbitrary array geometries, which shows a significant implementation advantage over most state-of-the-art unitary estimators including unitary MUSIC (U-MUSIC. Numerical simulations over a wide range of scenarios are conducted to show the performance of the new technique, which demonstrates that with a significantly reduced computational complexity, the new approach is able to provide a close accuracy to the standard MUSIC.

  2. Single snapshot DOA estimation

    Science.gov (United States)

    Häcker, P.; Yang, B.

    2010-10-01

    In array signal processing, direction of arrival (DOA) estimation has been studied for decades. Many algorithms have been proposed and their performance has been studied thoroughly. Yet, most of these works are focused on the asymptotic case of a large number of snapshots. In automotive radar applications like driver assistance systems, however, only a small number of snapshots of the radar sensor array or, in the worst case, a single snapshot is available for DOA estimation. In this paper, we investigate and compare different DOA estimators with respect to their single snapshot performance. The main focus is on the estimation accuracy and the angular resolution in multi-target scenarios including difficult situations like correlated targets and large target power differences. We will show that some algorithms lose their ability to resolve targets or do not work properly at all. Other sophisticated algorithms do not show a superior performance as expected. It turns out that the deterministic maximum likelihood estimator is a good choice under these hard conditions.

  3. Novel Direction Of Arrival Estimation Method Based on Coherent Accumulation Matrix Reconstruction

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    Li Lei

    2015-04-01

    Full Text Available Based on coherent accumulation matrix reconstruction, a novel Direction Of Arrival (DOA estimation decorrelation method of coherent signals is proposed using a small sample. First, the Signal to Noise Ratio (SNR is improved by performing coherent accumulation operation on an array of observed data. Then, according to the structure characteristics of the accumulated snapshot vector, the equivalent covariance matrix, whose rank is the same as the number of array elements, is constructed. The rank of this matrix is proved to be determined just by the number of incident signals, which realize the decorrelation of coherent signals. Compared with spatial smoothing method, the proposed method performs better by effectively avoiding aperture loss with high-resolution characteristics and low computational complexity. Simulation results demonstrate the efficiency of the proposed method.

  4. Sparse Method for Direction of Arrival Estimation Using Denoised Fourth-Order Cumulants Vector.

    Science.gov (United States)

    Fan, Yangyu; Wang, Jianshu; Du, Rui; Lv, Guoyun

    2018-06-04

    Fourth-order cumulants (FOCs) vector-based direction of arrival (DOA) estimation methods of non-Gaussian sources may suffer from poor performance for limited snapshots or difficulty in setting parameters. In this paper, a novel FOCs vector-based sparse DOA estimation method is proposed. Firstly, by utilizing the concept of a fourth-order difference co-array (FODCA), an advanced FOCs vector denoising or dimension reduction procedure is presented for arbitrary array geometries. Then, a novel single measurement vector (SMV) model is established by the denoised FOCs vector, and efficiently solved by an off-grid sparse Bayesian inference (OGSBI) method. The estimation errors of FOCs are integrated in the SMV model, and are approximately estimated in a simple way. A necessary condition regarding the number of identifiable sources of our method is presented that, in order to uniquely identify all sources, the number of sources K must fulfill K ≤ ( M 4 - 2 M 3 + 7 M 2 - 6 M ) / 8 . The proposed method suits any geometry, does not need prior knowledge of the number of sources, is insensitive to associated parameters, and has maximum identifiability O ( M 4 ) , where M is the number of sensors in the array. Numerical simulations illustrate the superior performance of the proposed method.

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

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    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.

  6. Improved ESPRIT Method for Joint Direction-of-Arrival and Frequency Estimation Using Multiple-Delay Output

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    Wang Xudong

    2012-01-01

    Full Text Available An automatic pairing joint direction-of-arrival (DOA and frequency estimation is presented to overcome the unsatisfactory performances of estimation of signal parameter via rotational invariance techniques- (ESPRIT- like algorithm of Wang (2010, which requires an additional pairing. By using multiple-delay output of a uniform linear antenna arrays (ULA, the proposed algorithm can estimate joint angles and frequencies with an improved ESPRIT. Compared with Wang’s ESPRIT algorithm, the angle estimation performance of the proposed algorithm is greatly improved. The frequency estimation performance of the proposed algorithm is same with that of Wang’s ESPRIT algorithm. Furthermore, the proposed algorithm can obtain automatic pairing DOA and frequency parameters, and it has a comparative computational complexity in contrast to Wang’s ESPRIT algorithm. By the way, this proposed algorithm can also work well for nonuniform linear arrays. The useful behavior of this proposed algorithm is verified by simulations.

  7. Statistically Efficient Methods for Pitch and DOA Estimation

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2013-01-01

    , it was recently considered to estimate the DOA and pitch jointly. In this paper, we propose two novel methods for DOA and pitch estimation. They both yield maximum-likelihood estimates in white Gaussian noise scenar- ios, where the SNR may be different across channels, as opposed to state-of-the-art methods......Traditionally, direction-of-arrival (DOA) and pitch estimation of multichannel, periodic sources have been considered as two separate problems. Separate estimation may render the task of resolving sources with similar DOA or pitch impossible, and it may decrease the estimation accuracy. Therefore...

  8. The Analysis of Sophisticated Direction of Arrival Estimation Methods in Passive Coherent Locators

    National Research Council Canada - National Science Library

    Ozcetin, Ahmet

    2002-01-01

    ...). The goal is to compare the ACMA to the MUSIC, and CBF algorithms for application to PCL. The results and analysis presented here support the use of constant modulus information, where available, as an important addition to DOA estimation...

  9. Robust DOA Estimation of Harmonic Signals Using Constrained Filters on Phase Estimates

    DEFF Research Database (Denmark)

    Karimian-Azari, Sam; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2014-01-01

    In array signal processing, distances between receivers, e.g., microphones, cause time delays depending on the direction of arrival (DOA) of a signal source. We can then estimate the DOA from the time-difference of arrival (TDOA) estimates. However, many conventional DOA estimators based on TDOA...... estimates are not optimal in colored noise. In this paper, we estimate the DOA of a harmonic signal source from multi-channel phase estimates, which relate to narrowband TDOA estimates. More specifically, we design filters to apply on phase estimates to obtain a DOA estimate with minimum variance. Using...

  10. Informed TDoA-based Direction of Arrival Estimation for Hearing Aid Applications

    DEFF Research Database (Denmark)

    Farmani, Mojtaba; Pedersen, Michael Syskind; Tan, Zheng-Hua

    2015-01-01

    Discrete Fourier Transform (IDFT) technique. To study the performance of the proposed algorithms, we run simulations for various DoAs, Signal to Noise Ratios (SNRs), and distances in large crowd noise situations. In these situations, the proposed estimator improves the estimation performance markedly over...

  11. Joint Direction-of-Departure and Direction-of-Arrival Estimation in a UWB MIMO Radar Detecting Targets with Fluctuating Radar Cross Sections

    Directory of Open Access Journals (Sweden)

    Idnin Pasya

    2014-01-01

    Full Text Available This paper presents a joint direction-of-departure (DOD and direction-of-arrival (DOA estimation in a multiple-input multiple-output (MIMO radar utilizing ultra wideband (UWB signals in detecting targets with fluctuating radar cross sections (RCS. The UWB MIMO radar utilized a combination of two-way MUSIC and majority decision based on angle histograms of estimated DODs and DOAs at each frequency of the UWB signal. The proposed angle estimation scheme was demonstrated to be effective in detecting targets with fluctuating RCS, compared to conventional spectra averaging method used in subband angle estimations. It was found that a wider bandwidth resulted in improved estimation performance. Numerical simulations along with experimental evaluations in a radio anechoic chamber are presented.

  12. Direction of Arrival Estimation Accuracy Enhancement via Using Displacement Invariance Technique

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    Youssef Fayad

    2015-01-01

    Full Text Available A new algorithm for improving Direction of Arrival Estimation (DOAE accuracy has been carried out. Two contributions are introduced. First, Doppler frequency shift that resulted from the target movement is estimated using the displacement invariance technique (DIT. Second, the effect of Doppler frequency is modeled and incorporated into ESPRIT algorithm in order to increase the estimation accuracy. It is worth mentioning that the subspace approach has been employed into ESPRIT and DIT methods to reduce the computational complexity and the model’s nonlinearity effect. The DOAE accuracy has been verified by closed-form Cramér-Rao bound (CRB. The simulation results of the proposed algorithm are better than those of the previous estimation techniques leading to the estimator performance enhancement.

  13. Direction-of-arrival estimation for co-located multiple-input multiple-output radar using structural sparsity Bayesian learning

    International Nuclear Information System (INIS)

    Wen Fang-Qing; Zhang Gong; Ben De

    2015-01-01

    This paper addresses the direction of arrival (DOA) estimation problem for the co-located multiple-input multiple-output (MIMO) radar with random arrays. The spatially distributed sparsity of the targets in the background makes compressive sensing (CS) desirable for DOA estimation. A spatial CS framework is presented, which links the DOA estimation problem to support recovery from a known over-complete dictionary. A modified statistical model is developed to accurately represent the intra-block correlation of the received signal. A structural sparsity Bayesian learning algorithm is proposed for the sparse recovery problem. The proposed algorithm, which exploits intra-signal correlation, is capable being applied to limited data support and low signal-to-noise ratio (SNR) scene. Furthermore, the proposed algorithm has less computation load compared to the classical Bayesian algorithm. Simulation results show that the proposed algorithm has a more accurate DOA estimation than the traditional multiple signal classification (MUSIC) algorithm and other CS recovery algorithms. (paper)

  14. Direction-of-arrival estimation for co-located multiple-input multiple-output radar using structural sparsity Bayesian learning

    Science.gov (United States)

    Wen, Fang-Qing; Zhang, Gong; Ben, De

    2015-11-01

    This paper addresses the direction of arrival (DOA) estimation problem for the co-located multiple-input multiple-output (MIMO) radar with random arrays. The spatially distributed sparsity of the targets in the background makes compressive sensing (CS) desirable for DOA estimation. A spatial CS framework is presented, which links the DOA estimation problem to support recovery from a known over-complete dictionary. A modified statistical model is developed to accurately represent the intra-block correlation of the received signal. A structural sparsity Bayesian learning algorithm is proposed for the sparse recovery problem. The proposed algorithm, which exploits intra-signal correlation, is capable being applied to limited data support and low signal-to-noise ratio (SNR) scene. Furthermore, the proposed algorithm has less computation load compared to the classical Bayesian algorithm. Simulation results show that the proposed algorithm has a more accurate DOA estimation than the traditional multiple signal classification (MUSIC) algorithm and other CS recovery algorithms. Project supported by the National Natural Science Foundation of China (Grant Nos. 61071163, 61271327, and 61471191), the Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics, China (Grant No. BCXJ14-08), the Funding of Innovation Program for Graduate Education of Jiangsu Province, China (Grant No. KYLX 0277), the Fundamental Research Funds for the Central Universities, China (Grant No. 3082015NP2015504), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PADA), China.

  15. Frequency Diversity Array for DOA Estimation

    Directory of Open Access Journals (Sweden)

    NAUMAN ANWAR BAIG

    2017-10-01

    Full Text Available The localization of targets has been presented in this article. DOA (Direction of Arrival is an important parameter to be determined by radar. The MLE (Maximum Likelihood Estimator has been widely used to accurately and efficiently estimate the DOAs of multiple targets. The targets at different ranges result in a variation in amplitude of the received signals, so an MLE estimator has to operate at all ranges. For accurate results of DOA, the complex amplitudes of multiple targets should not be much different and also the prior information of Doppler and number of targets is required. In this paper, an approach is proposed which uses the classical 2D algorithm to estimate range, Doppler and number of targets and then FDA (Frequency Diversity Array is used to focus power in a particular range. As a result, the MLE can get data from a particular range cell where all targets have almost same amplitude and thus MLE can accurately estimate the DOAs of multiple targets. Simulations and results have confirmed the effectiveness of proposed approach.

  16. Theory, Design, and Measurement of Novel Uniform Circular Antenna Arrays for Direction of Arrival Estimation

    Science.gov (United States)

    2015-01-01

    Queen in Right of Canada, as represented by the Minister of National Defence, 2015 c⃝ Sa Majesté la Reine (en droit du Canada), telle que réprésentée... publication in [1]. Sections 5 and 6 describe the design and fabrication of the three novel UCAs for DOA estimation and provide simulation results. Section...DoA resolution limits in MIMO channel sounding,” in 2004 IEEE International Symposium On Antennas and Propagation and USNC/URSI National Radio

  17. 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.

  18. The PARAFAC-MUSIC Algorithm for DOA Estimation with Doppler Frequency in a MIMO Radar System

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2014-01-01

    Full Text Available The PARAFAC-MUSIC algorithm is proposed to estimate the direction-of-arrival (DOA of the targets with Doppler frequency in a monostatic MIMO radar system in this paper. To estimate the Doppler frequency, the PARAFAC (parallel factor algorithm is firstly utilized in the proposed algorithm, and after the compensation of Doppler frequency, MUSIC (multiple signal classification algorithm is applied to estimate the DOA. By these two steps, the DOA of moving targets can be estimated successfully. Simulation results show that the proposed PARAFAC-MUSIC algorithm has a higher accuracy than the PARAFAC algorithm and the MUSIC algorithm in DOA estimation.

  19. Joint Pitch and DOA Estimation Using the ESPRIT method

    DEFF Research Database (Denmark)

    Wu, Yuntao; Amir, Leshem; Jensen, Jesper Rindom

    2015-01-01

    In this paper, the problem of joint multi-pitch and direction-of-arrival (DOA) estimation for multi-channel harmonic sinusoidal signals is considered. A spatio-temporal matrix signal model for a uniform linear array is defined, and then the ESPRIT method based on subspace techniques that exploits...... the invariance property in the time domain is first used to estimate the multi pitch frequencies of multiple harmonic signals. Followed by the estimated pitch frequencies, the DOA estimations based on the ESPRIT method are also presented by using the shift invariance structure in the spatial domain. Compared...... to the existing stateof-the-art algorithms, the proposed method based on ESPRIT without 2-D searching is computationally more efficient but performs similarly. An asymptotic performance analysis of the DOA and pitch estimation of the proposed method are also presented. Finally, the effectiveness of the proposed...

  20. Separate DOD and DOA Estimation for Bistatic MIMO Radar

    Directory of Open Access Journals (Sweden)

    Lin Li

    2016-01-01

    Full Text Available A novel MUSIC-type algorithm is derived in this paper for the direction of departure (DOD and direction of arrival (DOA estimation in a bistatic MIMO radar. Through rearranging the received signal matrix, we illustrate that the DOD and the DOA can be separately estimated. Compared with conventional MUSIC-type algorithms, the proposed separate MUSIC algorithm can avoid the interference between DOD and DOA estimations effectively. Therefore, it is expected to give a better angle estimation performance and have a much lower computational complexity. Meanwhile, we demonstrate that our method is also effective for coherent targets in MIMO radar. Simulation results verify the efficiency of the proposed method, particularly when the signal-to-noise ratio (SNR is low and/or the number of snapshots is small.

  1. Bound on the estimation grid size for sparse reconstruction in direction of arrival estimation

    NARCIS (Netherlands)

    Coutiño Minguez, M.A.; Pribic, R; Leus, G.J.T.

    2016-01-01

    A bound for sparse reconstruction involving both the signal-to-noise ratio (SNR) and the estimation grid size is presented. The bound is illustrated for the case of a uniform linear array (ULA). By reducing the number of possible sparse vectors present in the feasible set of a constrained ℓ1-norm

  2. 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.

  3. A Sum-of-Squares and Semidefinite Programming Approach for Maximum Likelihood DOA Estimation

    Directory of Open Access Journals (Sweden)

    Shu Cai

    2016-12-01

    Full Text Available Direction of arrival (DOA estimation using a uniform linear array (ULA is a classical problem in array signal processing. In this paper, we focus on DOA estimation based on the maximum likelihood (ML criterion, transform the estimation problem into a novel formulation, named as sum-of-squares (SOS, and then solve it using semidefinite programming (SDP. We first derive the SOS and SDP method for DOA estimation in the scenario of a single source and then extend it under the framework of alternating projection for multiple DOA estimation. The simulations demonstrate that the SOS- and SDP-based algorithms can provide stable and accurate DOA estimation when the number of snapshots is small and the signal-to-noise ratio (SNR is low. Moveover, it has a higher spatial resolution compared to existing methods based on the ML criterion.

  4. DOA Estimation of Audio Sources in Reverberant Environments

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Nielsen, Jesper Kjær; Heusdens, Richard

    2016-01-01

    Reverberation is well-known to have a detrimental impact on many localization methods for audio sources. We address this problem by imposing a model for the early reflections as well as a model for the audio source itself. Using these models, we propose two iterative localization methods...... that estimate the direction-of-arrival (DOA) of both the direct path of the audio source and the early reflections. In these methods, the contribution of the early reflections is essentially subtracted from the signal observations before localization of the direct path component, which may reduce the estimation...

  5. A FPC-ROOT Algorithm for 2D-DOA Estimation in Sparse Array

    Directory of Open Access Journals (Sweden)

    Wenhao Zeng

    2016-01-01

    Full Text Available To improve the performance of two-dimensional direction-of-arrival (2D DOA estimation in sparse array, this paper presents a Fixed Point Continuation Polynomial Roots (FPC-ROOT algorithm. Firstly, a signal model for DOA estimation is established based on matrix completion and it can be proved that the proposed model meets Null Space Property (NSP. Secondly, left and right singular vectors of received signals matrix are achieved using the matrix completion algorithm. Finally, 2D DOA estimation can be acquired through solving the polynomial roots. The proposed algorithm can achieve high accuracy of 2D DOA estimation in sparse array, without solving autocorrelation matrix of received signals and scanning of two-dimensional spectral peak. Besides, it decreases the number of antennas and lowers computational complexity and meanwhile avoids the angle ambiguity problem. Computer simulations demonstrate that the proposed FPC-ROOT algorithm can obtain the 2D DOA estimation precisely in sparse array.

  6. Sparse Bayesian Learning for DOA Estimation with Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Jisheng Dai

    2015-10-01

    Full Text Available Sparse Bayesian learning (SBL has given renewed interest to the problem of direction-of-arrival (DOA estimation. It is generally assumed that the measurement matrix in SBL is precisely known. Unfortunately, this assumption may be invalid in practice due to the imperfect manifold caused by unknown or misspecified mutual coupling. This paper describes a modified SBL method for joint estimation of DOAs and mutual coupling coefficients with uniform linear arrays (ULAs. Unlike the existing method that only uses stationary priors, our new approach utilizes a hierarchical form of the Student t prior to enforce the sparsity of the unknown signal more heavily. We also provide a distinct Bayesian inference for the expectation-maximization (EM algorithm, which can update the mutual coupling coefficients more efficiently. Another difference is that our method uses an additional singular value decomposition (SVD to reduce the computational complexity of the signal reconstruction process and the sensitivity to the measurement noise.

  7. Fundamental Frequency and Direction-of-Arrival Estimation for Multichannel Speech Enhancement

    DEFF Research Database (Denmark)

    Karimian-Azari, Sam

    Audio systems receive the speech signals of interest usually in the presence of noise. The noise has profound impacts on the quality and intelligibility of the speech signals, and it is therefore clear that the noisy signals must be cleaned up before being played back, stored, or analyzed. We can...... estimate the speech signal of interest from the noisy signals using a priori knowledge about it. A human speech signal is broadband and consists of both voiced and unvoiced parts. The voiced part is quasi-periodic with a time-varying fundamental frequency (or pitch as it is commonly referred to). We...... their time differences which eventually may further reduce the effects of noise. This thesis introduces a number of principles and methods to estimate periodic signals in noisy environments with application to multichannel speech enhancement. We propose model-based signal enhancement concerning the model...

  8. DOA estimation for attitude determination on communication satellites

    Directory of Open Access Journals (Sweden)

    Yang Bin

    2014-06-01

    Full Text Available In order to determine an appropriate attitude of three-axis stabilized communication satellites, this paper describes a novel attitude determination method using direction of arrival (DOA estimation of a ground signal source. It differs from optical measurement, magnetic field measurement, inertial measurement, and global positioning system (GPS attitude determination. The proposed method is characterized by taking the ground signal source as the attitude reference and acquiring attitude information from DOA estimation. Firstly, an attitude measurement equation with DOA estimation is derived in detail. Then, the error of the measurement equation is analyzed. Finally, an attitude determination algorithm is presented using a dynamic model, the attitude measurement equation, and measurement errors. A developing low Earth orbit (LEO satellite which tests mobile communication technology with smart antennas can be stabilized in three axes by corporately using a magnetometer, reaction wheels, and three-axis magnetorquer rods. Based on the communication satellite, simulation results demonstrate the effectiveness of the method. The method could be a backup of attitude determination to prevent a system failure on the satellite. Its precision depends on the number of snapshots and the input signal-to-noise ratio (SNR with DOA estimation.

  9. 2D-DOA and Mutual Coupling Estimation in Vehicle Communication System via Conformal Array

    Directory of Open Access Journals (Sweden)

    Yan Zou

    2015-01-01

    Full Text Available Many direction-of-arrival (DOA estimation algorithms have been proposed recently. However, the effect of mutual coupling among antenna elements has not been taken into consideration. In this paper, a novel DOA and mutual coupling coefficient estimation algorithm is proposed in intelligent transportation systems (ITS via conformal array. By constructing the spectial mutual coupling matrix (MCM, the effect of mutual coupling can be eliminated via instrumental element method. Then the DOA of incident signals can be estimated based on parallel factor (PARAFAC theory. The PARAFAC model is constructed in cumulant domain using covariance matrices. The mutual coupling coefficients are estimated based on the former DOA estimation and the matrix transformation between MCM and the steering vector. Finally, due to the drawback of the parameter pairing method in Wan et al., 2014, a novel method is given to improve the performance of parameter pairing. The computer simulation verifies the effectiveness of the proposed algorithm.

  10. DOA Estimation Based on Real-Valued Cross Correlation Matrix of Coprime Arrays.

    Science.gov (United States)

    Li, Jianfeng; Wang, Feng; Jiang, Defu

    2017-03-20

    A fast direction of arrival (DOA) estimation method using a real-valued cross-correlation matrix (CCM) of coprime subarrays is proposed. Firstly, real-valued CCM with extended aperture is constructed to obtain the signal subspaces corresponding to the two subarrays. By analysing the relationship between the two subspaces, DOA estimations from the two subarrays are simultaneously obtained with automatic pairing. Finally, unique DOA is determined based on the common results from the two subarrays. Compared to partial spectral search (PSS) method and estimation of signal parameter via rotational invariance (ESPRIT) based method for coprime arrays, the proposed algorithm has lower complexity but achieves better DOA estimation performance and handles more sources. Simulation results verify the effectiveness of the approach.

  11. DOA Estimation Based on Real-Valued Cross Correlation Matrix of Coprime Arrays

    Directory of Open Access Journals (Sweden)

    Jianfeng Li

    2017-03-01

    Full Text Available A fast direction of arrival (DOA estimation method using a real-valued cross-correlation matrix (CCM of coprime subarrays is proposed. Firstly, real-valued CCM with extended aperture is constructed to obtain the signal subspaces corresponding to the two subarrays. By analysing the relationship between the two subspaces, DOA estimations from the two subarrays are simultaneously obtained with automatic pairing. Finally, unique DOA is determined based on the common results from the two subarrays. Compared to partial spectral search (PSS method and estimation of signal parameter via rotational invariance (ESPRIT based method for coprime arrays, the proposed algorithm has lower complexity but achieves better DOA estimation performance and handles more sources. Simulation results verify the effectiveness of the approach.

  12. A Channelization-Based DOA Estimation Method for Wideband Signals

    Directory of Open Access Journals (Sweden)

    Rui Guo

    2016-07-01

    Full Text Available In this paper, we propose a novel direction of arrival (DOA estimation method for wideband signals with sensor arrays. The proposed method splits the wideband array output into multiple frequency sub-channels and estimates the signal parameters using a digital channelization receiver. Based on the output sub-channels, a channelization-based incoherent signal subspace method (Channelization-ISM and a channelization-based test of orthogonality of projected subspaces method (Channelization-TOPS are proposed. Channelization-ISM applies narrowband signal subspace methods on each sub-channel independently. Then the arithmetic mean or geometric mean of the estimated DOAs from each sub-channel gives the final result. Channelization-TOPS measures the orthogonality between the signal and the noise subspaces of the output sub-channels to estimate DOAs. The proposed channelization-based method isolates signals in different bandwidths reasonably and improves the output SNR. It outperforms the conventional ISM and TOPS methods on estimation accuracy and dynamic range, especially in real environments. Besides, the parallel processing architecture makes it easy to implement on hardware. A wideband digital array radar (DAR using direct wideband radio frequency (RF digitization is presented. Experiments carried out in a microwave anechoic chamber with the wideband DAR are presented to demonstrate the performance. The results verify the effectiveness of the proposed method.

  13. Efficient AM Algorithms for Stochastic ML Estimation of DOA

    Directory of Open Access Journals (Sweden)

    Haihua Chen

    2016-01-01

    Full Text Available The estimation of direction-of-arrival (DOA of signals is a basic and important problem in sensor array signal processing. To solve this problem, many algorithms have been proposed, among which the Stochastic Maximum Likelihood (SML is one of the most concerned algorithms because of its high accuracy of DOA. However, the estimation of SML generally involves the multidimensional nonlinear optimization problem. As a result, its computational complexity is rather high. This paper addresses the issue of reducing computational complexity of SML estimation of DOA based on the Alternating Minimization (AM algorithm. We have the following two contributions. First using transformation of matrix and properties of spatial projection, we propose an efficient AM (EAM algorithm by dividing the SML criterion into two components. One depends on a single variable parameter while the other does not. Second when the array is a uniform linear array, we get the irreducible form of the EAM criterion (IAM using polynomial forms. Simulation results show that both EAM and IAM can reduce the computational complexity of SML estimation greatly, while IAM is the best. Another advantage of IAM is that this algorithm can avoid the numerical instability problem which may happen in AM and EAM algorithms when more than one parameter converges to an identical value.

  14. DOA and Pitch Estimation of Audio Sources using IAA-based Filtering

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2014-01-01

    For decades, it has been investigated how to separately solve the problems of both direction-of-arrival (DOA) and pitch estimation. Recently, it was found that estimating these parameters jointly from multichannel recordings of audio can be extremely beneficial. Many joint estimators are based...... on knowledge of the inverse sample covariance matrix. Typically, this covariance is estimated using the sample covariance matrix, but for this estimate to be full rank, many temporal samples are needed. In cases with non-stationary signals, this is a serious limitation. We therefore investigate how a recent...... joint DOA and pitch filtering-based estimator can be combined with the iterative adaptive approach to circumvent this limitation in joint DOA and pitch estimation of audio sources. Simulations show a clear improvement compared to when using the sample covariance matrix and the considered approach also...

  15. The influence of random element displacement on DOA estimates obtained with (Khatri-Rao-)root-MUSIC.

    Science.gov (United States)

    Inghelbrecht, Veronique; Verhaevert, Jo; van Hecke, Tanja; Rogier, Hendrik

    2014-11-11

    Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to random errors in the array geometry. Therefore, we propose a stochastic collocation method that relies on a generalized polynomial chaos expansion to connect the statistical distribution of random position errors to the resulting distribution of the DOA estimates. We apply this technique to the conventional root-MUSIC and the Khatri-Rao-root-MUSIC methods. According to Monte-Carlo simulations, this novel approach yields a speedup by a factor of more than 100 in terms of CPU-time for a one-dimensional case and by a factor of 56 for a two-dimensional case.

  16. A Novel DOA Estimation Algorithm Using Array Rotation Technique

    Directory of Open Access Journals (Sweden)

    Xiaoyu Lan

    2014-03-01

    Full Text Available The performance of traditional direction of arrival (DOA estimation algorithm based on uniform circular array (UCA is constrained by the array aperture. Furthermore, the array requires more antenna elements than targets, which will increase the size and weight of the device and cause higher energy loss. In order to solve these issues, a novel low energy algorithm utilizing array base-line rotation for multiple targets estimation is proposed. By rotating two elements and setting a fixed time delay, even the number of elements is selected to form a virtual UCA. Then, the received data of signals will be sampled at multiple positions, which improves the array elements utilization greatly. 2D-DOA estimation of the rotation array is accomplished via multiple signal classification (MUSIC algorithms. Finally, the Cramer-Rao bound (CRB is derived and simulation results verified the effectiveness of the proposed algorithm with high resolution and estimation accuracy performance. Besides, because of the significant reduction of array elements number, the array antennas system is much simpler and less complex than traditional array.

  17. Tracking Positioning Algorithm for Direction of Arrival Based on Direction Lock Loop

    Directory of Open Access Journals (Sweden)

    Xiu-Zhi Cheng

    2015-06-01

    Full Text Available In order to solve the problem of poor real-time performance, low accuracy and high computational complexity in the traditional process of locating and tracking of Direction of Arrival (DOA of moving targets, this paper proposes a DOA algorithm based on the Direction Lock Loop (DILL which adopts Lock Loop structure to realize the estimation and location of DOA and can adjust the direction automatically along with the changes of a signal’s angular variation to track the position of the signal. Meanwhile, to reduce the influence of nonlinearity and noise on its performance, the UKF filter is designed for eliminating interference of the estimated target signal to improve accuracy of the signal tracking and stability of the system. Simulation results prove that the algorithm can not only get a high resolution DOA estimate signal, but can also locate and track multiple mobile targets effectively with enhanced accuracy, efficiency and stability.

  18. Surface return direction-of-arrival analysis for radar ice sounding surface clutter suppression

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Dall, Jørgen

    2015-01-01

    Airborne radar ice sounding is challenged by surface clutter masking the depth signal of interest. Surface clutter may even be prohibitive for potential space-based ice sounding radars. To some extent the radar antenna suppresses the surface clutter, and a multi-phase-center antenna in combination...... with coherent signal processing techniques can improve the suppression, in particular if the direction of arrival (DOA) of the clutter signal is estimated accurately. This paper deals with data-driven DOA estimation. By using P-band data from the ice shelf in Antarctica it is demonstrated that a varying...

  19. Wideband DOA Estimation through Projection Matrix Interpolation

    OpenAIRE

    Selva, J.

    2017-01-01

    This paper presents a method to reduce the complexity of the deterministic maximum likelihood (DML) estimator in the wideband direction-of-arrival (WDOA) problem, which is based on interpolating the array projection matrix in the temporal frequency variable. It is shown that an accurate interpolator like Chebyshev's is able to produce DML cost functions comprising just a few narrowband-like summands. Actually, the number of such summands is far smaller (roughly by factor ten in the numerical ...

  20. 2-D DOA Estimation of LFM Signals Based on Dechirping Algorithm and Uniform Circle Array

    Directory of Open Access Journals (Sweden)

    K. B. Cui

    2017-04-01

    Full Text Available Based on Dechirping algorithm and uniform circle array(UCA, a new 2-D direction of arrival (DOA estimation algorithm of linear frequency modulation (LFM signals is proposed in this paper. The algorithm uses the thought of Dechirping and regards the signal to be estimated which is received by the reference sensor as the reference signal and proceeds the difference frequency treatment with the signal received by each sensor. So the signal to be estimated becomes a single-frequency signal in each sensor. Then we transform the single-frequency signal to an isolated impulse through Fourier transform (FFT and construct a new array data model based on the prominent parts of the impulse. Finally, we respectively use multiple signal classification (MUSIC algorithm and rotational invariance technique (ESPRIT algorithm to realize 2-D DOA estimation of LFM signals. The simulation results verify the effectiveness of the algorithm proposed.

  1. Single-snapshot DOA estimation by using Compressed Sensing

    Science.gov (United States)

    Fortunati, Stefano; Grasso, Raffaele; Gini, Fulvio; Greco, Maria S.; LePage, Kevin

    2014-12-01

    This paper deals with the problem of estimating the directions of arrival (DOA) of multiple source signals from a single observation vector of an array data. In particular, four estimation algorithms based on the theory of compressed sensing (CS), i.e., the classical ℓ 1 minimization (or Least Absolute Shrinkage and Selection Operator, LASSO), the fast smooth ℓ 0 minimization, and the Sparse Iterative Covariance-Based Estimator, SPICE and the Iterative Adaptive Approach for Amplitude and Phase Estimation, IAA-APES algorithms, are analyzed, and their statistical properties are investigated and compared with the classical Fourier beamformer (FB) in different simulated scenarios. We show that unlike the classical FB, a CS-based beamformer (CSB) has some desirable properties typical of the adaptive algorithms (e.g., Capon and MUSIC) even in the single snapshot case. Particular attention is devoted to the super-resolution property. Theoretical arguments and simulation analysis provide evidence that a CS-based beamformer can achieve resolution beyond the classical Rayleigh limit. Finally, the theoretical findings are validated by processing a real sonar dataset.

  2. DOA estimation for conformal vector-sensor array using geometric algebra

    Science.gov (United States)

    Meng, Tianzhen; Wu, Minjie; Yuan, Naichang

    2017-12-01

    In this paper, the problem of direction of arrival (DOA) estimation is considered in the case of multiple polarized signals impinging on the conformal electromagnetic vector-sensor array (CVA). We focus on modeling the manifold holistically by a new mathematical tool called geometric algebra. Compared with existing methods, the presented one has two main advantages. Firstly, it acquires higher resolution by preserving the orthogonality of the signal components. Secondly, it avoids the cumbersome matrix operations while performing the coordinate transformations, and therefore, has a much lower computational complexity. Simulation results are provided to demonstrate the effectiveness of the proposed algorithm.

  3. Application of Artificial Neural Networks for Efficient High-Resolution 2D DOA Estimation

    Directory of Open Access Journals (Sweden)

    M. Agatonović

    2012-12-01

    Full Text Available A novel method to provide high-resolution Two-Dimensional Direction of Arrival (2D DOA estimation employing Artificial Neural Networks (ANNs is presented in this paper. The observed space is divided into azimuth and elevation sectors. Multilayer Perceptron (MLP neural networks are employed to detect the presence of a source in a sector while Radial Basis Function (RBF neural networks are utilized for DOA estimation. It is shown that a number of appropriately trained neural networks can be successfully used for the high-resolution DOA estimation of narrowband sources in both azimuth and elevation. The training time of each smaller network is significantly re¬duced as different training sets are used for networks in detection and estimation stage. By avoiding the spectral search, the proposed method is suitable for real-time ap¬plications as it provides DOA estimates in a matter of seconds. At the same time, it demonstrates the accuracy comparable to that of the super-resolution 2D MUSIC algorithm.

  4. Extended reactance domain algorithms for DoA estimation onto an ESPAR antennas

    Science.gov (United States)

    Harabi, F.; Akkar, S.; Gharsallah, A.

    2016-07-01

    Based on an extended reactance domain (RD) covariance matrix, this article proposes new alternatives for directions of arrival (DoAs) estimation of narrowband sources through an electronically steerable parasitic array radiator (ESPAR) antennas. Because of the centro symmetry of the classic ESPAR antennas, an unitary transformation is applied to the collected data that allow an important reduction in both computational cost and processing time and, also, an enhancement of the resolution capabilities of the proposed algorithms. Moreover, this article proposes a new approach for eigenvalues estimation through only some linear operations. The developed DoAs estimation algorithms based on this new approach has illustrated a good behaviour with less calculation cost and processing time as compared to other schemes based on the classic eigenvalues approach. The conducted simulations demonstrate that high-precision and high-resolution DoAs estimation can be reached especially in very closely sources situation and low sources power as compared to the RD-MUSIC algorithm and the RD-PM algorithm. The asymptotic behaviours of the proposed DoAs estimators are analysed in various scenarios and compared with the Cramer-Rao bound (CRB). The conducted simulations testify the high-resolution of the developed algorithms and prove the efficiently of the proposed approach.

  5. Radar velocity determination using direction of arrival measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.; Horndt, Volker

    2017-12-19

    The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis. This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.

  6. Experimental Results of Novel DoA Estimation Algorithms for Compact Reconfigurable Antennas

    Directory of Open Access Journals (Sweden)

    Henna Paaso

    2017-01-01

    Full Text Available Reconfigurable antenna systems have gained much attention for potential use in the next generation wireless systems. However, conventional direction-of-arrival (DoA estimation algorithms for antenna arrays cannot be used directly in reconfigurable antennas due to different design of the antennas. In this paper, we present an adjacent pattern power ratio (APPR algorithm for two-port composite right/left-handed (CRLH reconfigurable leaky-wave antennas (LWAs. Additionally, we compare the performances of the APPR algorithm and LWA-based MUSIC algorithms. We study how the computational complexity and the performance of the algorithms depend on number of selected radiation patterns. In addition, we evaluate the performance of the APPR and MUSIC algorithms with numerical simulations as well as with real world indoor measurements having both line-of-sight and non-line-of-sight components. Our performance evaluations show that the DoA estimates are in a considerably good agreement with the real DoAs, especially with the APPR algorithm. In summary, the APPR and MUSIC algorithms for DoA estimation along with the planar and compact LWA layout can be a valuable solution to enhance the performance of the wireless communication in the next generation systems.

  7. A Developed ESPRIT Algorithm for DOA Estimation

    Science.gov (United States)

    Fayad, Youssef; Wang, Caiyun; Cao, Qunsheng; Hafez, Alaa El-Din Sayed

    2015-05-01

    A novel algorithm for estimating direction of arrival (DOAE) for target, which aspires to contribute to increase the estimation process accuracy and decrease the calculation costs, has been carried out. It has introduced time and space multiresolution in Estimation of Signal Parameter via Rotation Invariance Techniques (ESPRIT) method (TS-ESPRIT) to realize subspace approach that decreases errors caused by the model's nonlinearity effect. The efficacy of the proposed algorithm is verified by using Monte Carlo simulation, the DOAE accuracy has evaluated by closed-form Cramér-Rao bound (CRB) which reveals that the proposed algorithm's estimated results are better than those of the normal ESPRIT methods leading to the estimator performance enhancement.

  8. Genetic algorithm-based improved DOA estimation using fourth-order cumulants

    Science.gov (United States)

    Ahmed, Ammar; Tufail, Muhammad

    2017-05-01

    Genetic algorithm (GA)-based direction of arrival (DOA) estimation is proposed using fourth-order cumulants (FOC) and ESPRIT principle which results in Multiple Invariance Cumulant ESPRIT algorithm. In the existing FOC ESPRIT formulations, only one invariance is utilised to estimate DOAs. The unused multiple invariances (MIs) must be exploited simultaneously in order to improve the estimation accuracy. In this paper, a fitness function based on a carefully designed cumulant matrix is developed which incorporates MIs present in the sensor array. Better DOA estimation can be achieved by minimising this fitness function. Moreover, the effectiveness of Newton's method as well as GA for this optimisation problem has been illustrated. Simulation results show that the proposed algorithm provides improved estimation accuracy compared to existing algorithms, especially in the case of low SNR, less number of snapshots, closely spaced sources and high signal and noise correlation. Moreover, it is observed that the optimisation using Newton's method is more likely to converge to false local optima resulting in erroneous results. However, GA-based optimisation has been found attractive due to its global optimisation capability.

  9. 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.

  10. MUSIC algorithm DoA estimation for cooperative node location in mobile ad hoc networks

    Science.gov (United States)

    Warty, Chirag; Yu, Richard Wai; ElMahgoub, Khaled; Spinsante, Susanna

    In recent years the technological development has encouraged several applications based on distributed communications network without any fixed infrastructure. The problem of providing a collaborative early warning system for multiple mobile nodes against a fast moving object. The solution is provided subject to system level constraints: motion of nodes, antenna sensitivity and Doppler effect at 2.4 GHz and 5.8 GHz. This approach consists of three stages. The first phase consists of detecting the incoming object using a highly directive two element antenna at 5.0 GHz band. The second phase consists of broadcasting the warning message using a low directivity broad antenna beam using 2× 2 antenna array which then in third phase will be detected by receiving nodes by using direction of arrival (DOA) estimation technique. The DOA estimation technique is used to estimate the range and bearing of the incoming nodes. The position of fast arriving object can be estimated using the MUSIC algorithm for warning beam DOA estimation. This paper is mainly intended to demonstrate the feasibility of early detection and warning system using a collaborative node to node communication links. The simulation is performed to show the behavior of detecting and broadcasting antennas as well as performance of the detection algorithm. The idea can be further expanded to implement commercial grade detection and warning system

  11. Two-Dimensional DOA Estimation in Compressed Sensing with Compressive-Reduced Dimension-lp-MUSIC

    Directory of Open Access Journals (Sweden)

    Weijian Si

    2015-01-01

    Full Text Available This paper presents a novel two-dimensional (2D direction of arrival (DOA estimation method in compressed sensing (CS to remove the estimation failure problem and achieve superior performance. The proposed method separates the steering vector into two parts to construct two corresponding noise subspaces by introducing electric angles. Then, electric angles are estimated based on the constructed noise subspaces. In order to estimate the azimuth and elevation angles in terms of estimates of electric angles, arc-tangent operations are exploited. The arc-tangent is a one-to-one function and allows the value of the argument to be larger than unity so that the proposed method never fails. The proposed method can avoid pair matching to reduce the computational complexity and extend the number of snapshots to improve performance. Simulation results show that the proposed method can avoid estimation failure occurrence and has superior performance as compared to existing methods.

  12. GMTI Direction of Arrival Measurements from Multiple Phase Centers.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Ground Moving Target Indicator (GMTI) radar attempts to detect and locate targets with unknown motion. Very slow-moving targets are difficult to locate in the presence of surrounding clutter. This necessitates multiple antenna phase centers (or equivalent) to offer independent Direction of Arrival (DOA) measurements. DOA accuracy and precision generally remains dependent on target Signal-to-Noise Ratio (SNR), Clutter-toNoise Ratio (CNR), scene topography, interfering signals, and a number of antenna parameters. This is true even for adaptive techniques like Space-Time-AdaptiveProcessing (STAP) algorithms.

  13. Maximum Likelihood DOA Estimation of Multiple Wideband Sources in the Presence of Nonuniform Sensor Noise

    Directory of Open Access Journals (Sweden)

    K. Yao

    2007-12-01

    Full Text Available We investigate the maximum likelihood (ML direction-of-arrival (DOA estimation of multiple wideband sources in the presence of unknown nonuniform sensor noise. New closed-form expression for the direction estimation Cramér-Rao-Bound (CRB has been derived. The performance of the conventional wideband uniform ML estimator under nonuniform noise has been studied. In order to mitigate the performance degradation caused by the nonuniformity of the noise, a new deterministic wideband nonuniform ML DOA estimator is derived and two associated processing algorithms are proposed. The first algorithm is based on an iterative procedure which stepwise concentrates the log-likelihood function with respect to the DOAs and the noise nuisance parameters, while the second is a noniterative algorithm that maximizes the derived approximately concentrated log-likelihood function. The performance of the proposed algorithms is tested through extensive computer simulations. Simulation results show the stepwise-concentrated ML algorithm (SC-ML requires only a few iterations to converge and both the SC-ML and the approximately-concentrated ML algorithm (AC-ML attain a solution close to the derived CRB at high signal-to-noise ratio.

  14. Application of Matrix Pencil Algorithm to Mobile Robot Localization Using Hybrid DOA/TOA Estimation

    Directory of Open Access Journals (Sweden)

    Lan Anh Trinh

    2012-12-01

    Full Text Available Localization plays an important role in robotics for the tasks of monitoring, tracking and controlling a robot. Much effort has been made to address robot localization problems in recent years. However, despite many proposed solutions and thorough consideration, in terms of developing a low-cost and fast processing method for multiple-source signals, the robot localization problem is still a challenge. In this paper, we propose a solution for robot localization with regards to these concerns. In order to locate the position of a robot, both the coordinate and the orientation of a robot are necessary. We develop a localization method using the Matrix Pencil (MP algorithm for hybrid detection of direction of arrival (DOA and time of arrival (TOA. TOA of the signal is estimated for computing the distance between the mobile robot and a base station (BS. Based on the distance and the estimated DOA, we can estimate the mobile robot's position. The characteristics of the algorithm are examined through analysing simulated experiments and the results demonstrate the advantages of our method over previous works in dealing with the above challenges. The method is constructed based on the low-cost infrastructure of radio frequency devices; the DOA/TOA estimation is performed with just single value decomposition for fast processing. Finally, the MP algorithm combined with tracking using a Kalman filter allows our proposed method to locate the positions of multiple source signals.

  15. 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.

  16. Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle

    Directory of Open Access Journals (Sweden)

    Junpeng Shi

    2017-02-01

    Full Text Available In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS method for two-dimensional direction of arrival (2D DOA estimation with uniform rectangular arrays (URAs in a low-grazing angle (LGA condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions.

  17. Reduced complexity FFT-based DOA and DOD estimation for moving target in bistatic MIMO radar

    KAUST Repository

    Ali, Hussain

    2016-06-24

    In this paper, we consider a bistatic multiple-input multiple-output (MIMO) radar. We propose a reduced complexity algorithm to estimate the direction-of-arrival (DOA) and direction-of-departure (DOD) for moving target. We show that the calculation of parameter estimation can be expressed in terms of one-dimensional fast-Fourier-transforms which drastically reduces the complexity of the optimization algorithm. The performance of the proposed algorithm is compared with the two-dimension multiple signal classification (2D-MUSIC) and reduced-dimension MUSIC (RD-MUSIC) algorithms. It is shown by simulations, our proposed algorithm has better estimation performance and lower computational complexity compared to the 2D-MUSIC and RD-MUSIC algorithms. Moreover, simulation results also show that the proposed algorithm achieves the Cramer-Rao lower bound. © 2016 IEEE.

  18. DOA Estimation of Low Altitude Target Based on Adaptive Step Glowworm Swarm Optimization-multiple Signal Classification Algorithm

    Directory of Open Access Journals (Sweden)

    Zhou Hao

    2015-06-01

    Full Text Available The traditional MUltiple SIgnal Classification (MUSIC algorithm requires significant computational effort and can not be employed for the Direction Of Arrival (DOA estimation of targets in a low-altitude multipath environment. As such, a novel MUSIC approach is proposed on the basis of the algorithm of Adaptive Step Glowworm Swarm Optimization (ASGSO. The virtual spatial smoothing of the matrix formed by each snapshot is used to realize the decorrelation of the multipath signal and the establishment of a fullorder correlation matrix. ASGSO optimizes the function and estimates the elevation of the target. The simulation results suggest that the proposed method can overcome the low altitude multipath effect and estimate the DOA of target readily and precisely without radar effective aperture loss.

  19. A New Method for the 2D DOA Estimation of Coherently Distributed Sources

    Directory of Open Access Journals (Sweden)

    Liang Zhou

    2014-03-01

    Full Text Available The purpose of this paper is to develop a new technique for estimating the two- dimensional (2D direction-of-arrivals (DOAs of coherently distributed (CD sources, which can estimate effectively the central azimuth and central elevation of CD sources at the cost of less computational cost. Using the special L-shape array, a new approach for parametric estimation of CD sources is proposed. The proposed method is based on two rotational invariance relations under small angular approximation, and estimates two rotational matrices which depict the relations, using propagator technique. And then the central DOA estimations are obtained by utilizing the primary diagonal elements of two rotational matrices. Simulation results indicate that the proposed method can exhibit a good performance under small angular spread and be applied to the multisource scenario where different sources may have different angular distribution shapes. Without any peak-finding search and the eigendecomposition of the high-dimensional sample covariance matrix, the proposed method has significantly reduced the computational cost compared with the existing methods, and thus is beneficial to real-time processing and engineering realization. In addition, our approach is also a robust estimator which does not depend on the angular distribution shape of CD sources.

  20. Multisnapshot Sparse Bayesian Learning for DOA

    DEFF Research Database (Denmark)

    Gerstoft, Peter; Mecklenbrauker, Christoph F.; Xenaki, Angeliki

    2016-01-01

    The directions of arrival (DOA) of plane waves are estimated from multisnapshot sensor array data using sparse Bayesian learning (SBL). The prior for the source amplitudes is assumed independent zero-mean complex Gaussian distributed with hyperparameters, the unknown variances (i.e., the source...

  1. Digital Beam Forming and Compressive Sensing Based DOA Estimation in MIMO Arrays

    NARCIS (Netherlands)

    Belfiori, F.; Anitori, L.; Rossum, W.L. van; Otten, M.P.G.; Hoogeboom, P.

    2011-01-01

    The paper presents different processing schemes that have been investigated in order to evaluate the direction of arrival (DOA) with a multiple-input multiple-output (MIMO) radar. Conventional digital beam forming (DBF) and super resolution algorithm (MUSIC) have been applied. The results provided

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

    Directory of Open Access Journals (Sweden)

    Xueqiang Chen

    2015-01-01

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

  3. Two-Dimensional DOA Estimation Using Arbitrary Arrays for Massive MIMO Systems

    Directory of Open Access Journals (Sweden)

    Alban Doumtsop Lonkeng

    2017-01-01

    Full Text Available With the quick advancement of wireless communication networks, the need for massive multiple-input-multiple-output (MIMO to offer adequate network capacity has turned out to be apparent. As a portion of array signal processing, direction-of-arrival (DOA estimation is of indispensable significance to acquire directional data of sources and to empower the 3D beamforming. In this paper, the performance of DOA estimation for massive MIMO systems is analyzed and compared using a low-complexity algorithm. To be exact, the 2D Fourier domain line search (FDLS MUSIC algorithm is studied to mutually estimate elevation and azimuth angle, and arbitrary array geometry is utilized to represent massive MIMO systems. To avoid the computational burden in estimating the data covariance matrix and its eigenvalue decomposition (EVD due to the large-scale sensors involved in massive MIMO systems, the reduced-dimension data matrix is applied on the signals received by the array. The performance is examined and contrasted with the 2D MUSIC algorithm for different types of antenna configuration. Finally, the array resolution is selected to investigate the performance of elevation and azimuth estimation. The effectiveness and advantage of the proposed technique have been proven by detailed simulations for different types of MIMO array configuration.

  4. Computationally Efficient 2D DOA Estimation for L-Shaped Array with Unknown Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Yang-Yang Dong

    2018-01-01

    Full Text Available Although L-shaped array can provide good angle estimation performance and is easy to implement, its two-dimensional (2D direction-of-arrival (DOA performance degrades greatly in the presence of mutual coupling. To deal with the mutual coupling effect, a novel 2D DOA estimation method for L-shaped array with low computational complexity is developed in this paper. First, we generalize the conventional mutual coupling model for L-shaped array and compensate the mutual coupling blindly via sacrificing a few sensors as auxiliary elements. Then we apply the propagator method twice to mitigate the effect of strong source signal correlation effect. Finally, the estimations of azimuth and elevation angles are achieved simultaneously without pair matching via the complex eigenvalue technique. Compared with the existing methods, the proposed method is computationally efficient without spectrum search or polynomial rooting and also has fine angle estimation performance for highly correlated source signals. Theoretical analysis and simulation results have demonstrated the effectiveness of the proposed method.

  5. A Novel Modification of PSO Algorithm for SML Estimation of DOA

    Directory of Open Access Journals (Sweden)

    Haihua Chen

    2016-12-01

    Full Text Available This paper addresses the issue of reducing the computational complexity of Stochastic Maximum Likelihood (SML estimation of Direction-of-Arrival (DOA. The SML algorithm is well-known for its high accuracy of DOA estimation in sensor array signal processing. However, its computational complexity is very high because the estimation of SML criteria is a multi-dimensional non-linear optimization problem. As a result, it is hard to apply the SML algorithm to real systems. The Particle Swarm Optimization (PSO algorithm is considered as a rather efficient method for multi-dimensional non-linear optimization problems in DOA estimation. However, the conventional PSO algorithm suffers two defects, namely, too many particles and too many iteration times. Therefore, the computational complexity of SML estimation using conventional PSO algorithm is still a little high. To overcome these two defects and to reduce computational complexity further, this paper proposes a novel modification of the conventional PSO algorithm for SML estimation and we call it Joint-PSO algorithm. The core idea of the modification lies in that it uses the solution of Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT and stochastic Cramer-Rao bound (CRB to determine a novel initialization space. Since this initialization space is already close to the solution of SML, fewer particles and fewer iteration times are needed. As a result, the computational complexity can be greatly reduced. In simulation, we compare the proposed algorithm with the conventional PSO algorithm, the classic Altering Minimization (AM algorithm and Genetic algorithm (GA. Simulation results show that our proposed algorithm is one of the most efficient solving algorithms and it shows great potential for the application of SML in real systems.

  6. DOA Estimation of Cylindrical Conformal Array Based on Geometric Algebra

    Directory of Open Access Journals (Sweden)

    Minjie Wu

    2016-01-01

    Full Text Available Due to the variable curvature of the conformal carrier, the pattern of each element has a different direction. The traditional method of analyzing the conformal array is to use the Euler rotation angle and its matrix representation. However, it is computationally demanding especially for irregular array structures. In this paper, we present a novel algorithm by combining the geometric algebra with Multiple Signal Classification (MUSIC, termed as GA-MUSIC, to solve the direction of arrival (DOA for cylindrical conformal array. And on this basis, we derive the pattern and array manifold. Compared with the existing algorithms, our proposed one avoids the cumbersome matrix transformations and largely decreases the computational complexity. The simulation results verify the effectiveness of the proposed method.

  7. DOA and Polarization Estimation Using an Electromagnetic Vector Sensor Uniform Circular Array Based on the ESPRIT Algorithm.

    Science.gov (United States)

    Wu, Na; Qu, Zhiyu; Si, Weijian; Jiao, Shuhong

    2016-12-13

    In array signal processing systems, the direction of arrival (DOA) and polarization of signals based on uniform linear or rectangular sensor arrays are generally obtained by rotational invariance techniques (ESPRIT). However, since the ESPRIT algorithm relies on the rotational invariant structure of the received data, it cannot be applied to electromagnetic vector sensor arrays (EVSAs) featuring uniform circular patterns. To overcome this limitation, a fourth-order cumulant-based ESPRIT algorithm is proposed in this paper, for joint estimation of DOA and polarization based on a uniform circular EVSA. The proposed algorithm utilizes the fourth-order cumulant to obtain a virtual extended array of a uniform circular EVSA, from which the pairs of rotation invariant sub-arrays are obtained. The ESPRIT algorithm and parameter pair matching are then utilized to estimate the DOA and polarization of the incident signals. The closed-form parameter estimation algorithm can effectively reduce the computational complexity of the joint estimation, which has been demonstrated by numerical simulations.

  8. Direction-of-Arrival Analysis of Airborne Ice Depth Sounder Data

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Yan, Jie-Bang; Gogineni, Sivaprasad

    2017-01-01

    In this paper, we analyze the direction-of arrival(DOA) of the ice-sheet data collected over Jakobshavn Glacier with the airborne Multichannel Radar Depth Sounder (MCRDS) during the 2006 field season. We extracted weak ice–bed echoes buried in signals scattered by the rough surface of the fast...

  9. Measurement reduction for mutual coupling calibration in DOA estimation

    Science.gov (United States)

    Aksoy, Taylan; Tuncer, T. Engin

    2012-01-01

    Mutual coupling is an important source of error in antenna arrays that should be compensated for super resolution direction-of-arrival (DOA) algorithms, such as Multiple Signal Classification (MUSIC) algorithm. A crucial step in array calibration is the determination of the mutual coupling coefficients for the antenna array. In this paper, a system theoretic approach is presented for the mutual coupling characterization of antenna arrays. The comprehension and implementation of this approach is simple leading to further advantages in calibration measurement reduction. In this context, a measurement reduction method for antenna arrays with omni-directional and identical elements is proposed which is based on the symmetry planes in the array geometry. The proposed method significantly decreases the number of measurements during the calibration process. This method is evaluated using different array types whose responses and the mutual coupling characteristics are obtained through numerical electromagnetic simulations. It is shown that a single calibration measurement is sufficient for uniform circular arrays. Certain important and interesting characteristics observed during the experiments are outlined.

  10. 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.

  11. Biological Inspired Stochastic Optimization Technique (PSO for DOA and Amplitude Estimation of Antenna Arrays Signal Processing in RADAR Communication System

    Directory of Open Access Journals (Sweden)

    Khurram Hammed

    2016-01-01

    Full Text Available This paper presents a stochastic global optimization technique known as Particle Swarm Optimization (PSO for joint estimation of amplitude and direction of arrival of the targets in RADAR communication system. The proposed scheme is an excellent optimization methodology and a promising approach for solving the DOA problems in communication systems. Moreover, PSO is quite suitable for real time scenario and easy to implement in hardware. In this study, uniform linear array is used and targets are supposed to be in far field of the arrays. Formulation of the fitness function is based on mean square error and this function requires a single snapshot to obtain the best possible solution. To check the accuracy of the algorithm, all of the results are taken by varying the number of antenna elements and targets. Finally, these results are compared with existing heuristic techniques to show the accuracy of PSO.

  12. A RD-ESPRIT algorithm for coherent DOA estimation in monostatic MIMO radar using a single pulse

    Science.gov (United States)

    Chen, Chen; Zhang, Xiaofei

    2014-08-01

    This paper discusses the problem of coherent direction of arrival (DOA) estimation in a monostatic multi-input multi-output (MIMO) radar using a single pulse, and proposes a reduced dimension (RD)-estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm. We reconstruct the received data and then utilise it to construct a set of Toeplitz matrices. After that, we use RD-ESPRIT to obtain the DOAs of the sources. The proposed algorithm is effective for coherent angle estimation based on a single pulse, and it has much better angle estimation performance than the forward backward spatial smoothing (FBSS)-ESPRIT algorithm and the ESPRIT-like of Li, as well as very close angle estimation performance to the ESPRIT-like of Han. For complexity comparison, our algorithm has very close complexity to the FBSS-ESPRIT algorithm, and lower complexity than the ESPRIT-like of Han and the ESPRIT-like of Li. Simulation results present the effectiveness and improvement of our approach.

  13. Primena metode MUSIC za određivanje smera dolaska radio-signala korišćenjem antenskih nizova ADCOCK / Application of the MUSIC method for direction of arrival estimation using the ADCOCK antenna arrays

    Directory of Open Access Journals (Sweden)

    Miljko M. Erić

    2002-01-01

    Full Text Available Analiziran je problem procene smera dolaska radio-signala metodom MUSIC korišćenjem antenskih nizova ADCOCK. Formulisan je matematički model signala na antenskom nizu ADCOCK. Izvedene su relacije između vektora prostiranja ADCOCK i vektora prostiranja ukupnog antenskog niza (niza od koga se ADCOCK-ov niz formira. Definisana je kriterijumska funkcija algoritma MUSIC i funkcija neodređenosti antenskog niza ADCOCK. Prikazani su rezultati simulacije, kao i rezultati praktične verifikacije mogućnosti primene metode MUSIC na antenske nizove ADCOCK. / The MUSIC based Direction of Arrival estimation using the ADCOCK antenna arrays is considered. Starting from signal model formulation, the cost function of the MUSIC algorithm and the ambiguity functions for the ADCOCK antenna array have been formulated. Some simulation results and some preliminary results of the verification in practice are presented.

  14. An Application of Artificial Intelligence for the Joint Estimation of Amplitude and Two-Dimensional Direction of Arrival of Far Field Sources Using 2-L-Shape Array

    Directory of Open Access Journals (Sweden)

    Fawad Zaman

    2013-01-01

    Full Text Available An easy and efficient approach, based on artificial intelligence technique, is proposed to jointly estimate the amplitude, elevation, and azimuth angles of far field sources impinging on 2-L-shape array. In these proposed artificial intelligence techniques, the metaheuristics based on genetic algorithm and simulated annealing are used as global optimizers assisted with rapid local version of pattern search for optimization of the adaptive parameters. The performance metric is employed on a fitness evaluation function depending on mean square error which is optimum and requires single snapshot to converge. The proposed approaches are easy to understand, and simple to implement; the genetic algorithm specifically hybridized with pattern search generates fairly good results. The comparison of the given schemes is carried out with 1-L-shape array, as well as, with parallel-shape array and is found to be in good agreement in terms of accuracy, convergence rate, computational complexity, and mean square error. The effectiveness and efficiency of the given schemes are examined through Monte Carlo simulations and their inclusive statistical analysis.

  15. DOA Estimation of Multiple LFM Sources Using a STFT-based and FBSS-based MUSIC Algorithm

    Directory of Open Access Journals (Sweden)

    K. B. Cui

    2017-12-01

    Full Text Available Direction of arrival (DOA estimation is an important problem in array signal processing. An effective multiple signal classification (MUSIC method based on the short-time Fourier transform (STFT and forward/ backward spatial smoothing (FBSS techniques for the DOA estimation problem of multiple time-frequency (t-f joint LFM sources is addressed. Previous work in the area e. g. STFT-MUSIC algorithm cannot resolve the t-f completely or largely joint sources because they can only select the single-source t-f points. The proposed method con¬structs the spatial t-f distributions (STFDs by selecting the multiple-source t-f points and uses the FBSS techniques to solve the problem of rank loss. In this way, the STFT-FBSS-MUSIC algorithm can resolve the t-f largely joint or completely joint LFM sources. In addition, the proposed algorithm also owns pretty low computational complexity when resolving multiple LFM sources because it can reduce the times of the feature decomposition and spectrum search. The performance of the proposed method is compared with that of the existing t-f based MUSIC algorithms through computer simulations and the results show its good performance.

  16. Airborne DoA estimation of gunshot acoustic signals using drones with application to sniper localization systems

    Science.gov (United States)

    Fernandes, Rigel P.; Ramos, António L. L.; Apolinário, José A.

    2017-05-01

    Shooter localization systems have been subject of a growing attention lately owing to its wide span of possible applications, e.g., civil protection, law enforcement, and support to soldiers in missions where snipers might pose a serious threat. These devices are based on the processing of electromagnetic or acoustic signatures associated with the firing of a gun. This work is concerned with the latter, where the shooter's position can be obtained based on the estimation of the direction-of-arrival (DoA) of the acoustic components of a gunshot signal (muzzle blast and shock wave). A major limitation of current commercially available acoustic sniper localization systems is the impossibility of finding the shooter's position when one of these acoustic signatures is not detected. This is very likely to occur in real-life situations, especially when the microphones are not in the field of view of the shockwave or when the presence of obstacles like buildings can prevent a direct-path to sensors. This work addresses the problem of DoA estimation of the muzzle blast using a planar array of sensors deployed in a drone. Results supported by actual gunshot data from a realistic setup are very promising and pave the way for the development of enhanced sniper localization systems featuring two main advantages over stationary ones: (1) wider surveillance area; and (2) increased likelihood of a direct-path detection of at least one of the gunshot signals, thereby adding robustness and reliability to the system.

  17. Computationally Efficient and Noise Robust DOA and Pitch Estimation

    DEFF Research Database (Denmark)

    Karimian-Azari, Sam; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2016-01-01

    Many natural signals, such as voiced speech and some musical instruments, are approximately periodic over short intervals. These signals are often described in mathematics by the sum of sinusoids (harmonics) with frequencies that are proportional to the fundamental frequency, or pitch. In sensor...... a joint DOA and pitch estimator. In white Gaussian noise, we derive even more computationally efficient solutions which are designed using the narrowband power spectrum of the harmonics. Numerical results reveal the performance of the estimators in colored noise compared with the Cram\\'{e}r-Rao lower...

  18. A Fast DOA Estimation Algorithm Based on Polarization MUSIC

    Directory of Open Access Journals (Sweden)

    R. Guo

    2015-04-01

    Full Text Available A fast DOA estimation algorithm developed from MUSIC, which also benefits from the processing of the signals' polarization information, is presented. Besides performance enhancement in precision and resolution, the proposed algorithm can be exerted on various forms of polarization sensitive arrays, without specific requirement on the array's pattern. Depending on the continuity property of the space spectrum, a huge amount of computation incurred in the calculation of 4-D space spectrum is averted. Performance and computation complexity analysis of the proposed algorithm is discussed and the simulation results are presented. Compared with conventional MUSIC, it is indicated that the proposed algorithm has considerable advantage in aspects of precision and resolution, with a low computation complexity proportional to a conventional 2-D MUSIC.

  19. ESPRIT-Like Two-Dimensional DOA Estimation for Monostatic MIMO Radar with Electromagnetic Vector Received Sensors under the Condition of Gain and Phase Uncertainties and Mutual Coupling.

    Science.gov (United States)

    Zhang, Dong; Zhang, Yongshun; Zheng, Guimei; Feng, Cunqian; Tang, Jun

    2017-10-26

    In this paper, we focus on the problem of two-dimensional direction of arrival (2D-DOA) estimation for monostatic MIMO Radar with electromagnetic vector received sensors (MIMO-EMVSs) under the condition of gain and phase uncertainties (GPU) and mutual coupling (MC). GPU would spoil the invariance property of the EMVSs in MIMO-EMVSs, thus the effective ESPRIT algorithm unable to be used directly. Then we put forward a C-SPD ESPRIT-like algorithm. It estimates the 2D-DOA and polarization station angle (PSA) based on the instrumental sensors method (ISM). The C-SPD ESPRIT-like algorithm can obtain good angle estimation accuracy without knowing the GPU. Furthermore, it can be applied to arbitrary array configuration and has low complexity for avoiding the angle searching procedure. When MC and GPU exist together between the elements of EMVSs, in order to make our algorithm feasible, we derive a class of separated electromagnetic vector receiver and give the S-SPD ESPRIT-like algorithm. It can solve the problem of GPU and MC efficiently. And the array configuration can be arbitrary. The effectiveness of our proposed algorithms is verified by the simulation result.

  20. ESPRIT-Like Two-Dimensional DOA Estimation for Monostatic MIMO Radar with Electromagnetic Vector Received Sensors under the Condition of Gain and Phase Uncertainties and Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Dong Zhang

    2017-10-01

    Full Text Available In this paper, we focus on the problem of two-dimensional direction of arrival (2D-DOA estimation for monostatic MIMO Radar with electromagnetic vector received sensors (MIMO-EMVSs under the condition of gain and phase uncertainties (GPU and mutual coupling (MC. GPU would spoil the invariance property of the EMVSs in MIMO-EMVSs, thus the effective ESPRIT algorithm unable to be used directly. Then we put forward a C-SPD ESPRIT-like algorithm. It estimates the 2D-DOA and polarization station angle (PSA based on the instrumental sensors method (ISM. The C-SPD ESPRIT-like algorithm can obtain good angle estimation accuracy without knowing the GPU. Furthermore, it can be applied to arbitrary array configuration and has low complexity for avoiding the angle searching procedure. When MC and GPU exist together between the elements of EMVSs, in order to make our algorithm feasible, we derive a class of separated electromagnetic vector receiver and give the S-SPD ESPRIT-like algorithm. It can solve the problem of GPU and MC efficiently. And the array configuration can be arbitrary. The effectiveness of our proposed algorithms is verified by the simulation result.

  1. Computationally Efficient DOA Tracking Algorithm in Monostatic MIMO Radar with Automatic Association

    Directory of Open Access Journals (Sweden)

    Huaxin Yu

    2014-01-01

    Full Text Available We consider the problem of tracking the direction of arrivals (DOA of multiple moving targets in monostatic multiple-input multiple-output (MIMO radar. A low-complexity DOA tracking algorithm in monostatic MIMO radar is proposed. The proposed algorithm obtains DOA estimation via the difference between previous and current covariance matrix of the reduced-dimension transformation signal, and it reduces the computational complexity and realizes automatic association in DOA tracking. Error analysis and Cramér-Rao lower bound (CRLB of DOA tracking are derived in the paper. The proposed algorithm not only can be regarded as an extension of array-signal-processing DOA tracking algorithm in (Zhang et al. (2008, but also is an improved version of the DOA tracking algorithm in (Zhang et al. (2008. Furthermore, the proposed algorithm has better DOA tracking performance than the DOA tracking algorithm in (Zhang et al. (2008. The simulation results demonstrate effectiveness of the proposed algorithm. Our work provides the technical support for the practical application of MIMO radar.

  2. Joint Spatio-Temporal Filtering Methods for DOA and Fundamental Frequency Estimation

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Benesty, Jacob

    2015-01-01

    some attention in the community and is quite promising for several applications. The proposed methods are based on optimal, adaptive filters that leave the desired signal, having a certain DOA and fundamental frequency, undistorted and suppress everything else. The filtering methods simultaneously...... operate in space and time, whereby it is possible resolve cases that are otherwise problematic for pitch estimators or DOA estimators based on beamforming. Several special cases and improvements are considered, including a method for estimating the covariance matrix based on the recently proposed...

  3. 高效超分辨波达方向估计算法综述%Overview of efficient algorithms for super-resolution DOA estimates

    Institute of Scientific and Technical Information of China (English)

    闫锋刚; 沈毅; 刘帅; 金铭; 乔晓林

    2015-01-01

    Computationally efficient methods for super-resolution direction of arrival (DOA)estimation aim to reduce the complexity of conventional techniques,to economize on the costs of systems and to enhance the ro-bustness of DOA estimators against array geometries and other environmental restrictions,which has been an important topic in the field.According to the theory and elements of the multiple signal classification (MUSIC) algorithm and the primary derivations from MUSIC,state-of-the-art efficient super-resolution DOA estimators are classified into five different types.These five types of approaches reduce the complexity by real-valued com-putation,beam-space transformation,fast subspace estimation,rapid spectral search,and no spectral search, respectively.With such a classification,comprehensive overviews of each kind of efficient methods are given and numerical comparisons among these estimators are also conducted to illustrate their advantages.Future develop-ment trends of efficient algorithms for super-resolution DOA estimates are finally predicted with basic require-ments of real-world applications.%高效超分辨波达方向估计算法致力于降低超分辨算法的计算量、节约系统的实现成本、弱化算法对于阵列结构的依赖性,是推进超分辨理论工程化的一个重要研究课题。从多重信号分类(multiple signal classifi-cation,MUSIC)算法的原理和构成要素入手,以基于 MUSIC 派生高效超分辨算法的目的和方法为标准,将现存高效超分辨算法划分为实值运算、波束域变换、快速子空间估计、快速峰值搜索和免峰值搜索5大类。在此基础上,全面回顾总结了各类高效算法的发展历程和最新进展,对比分析了它们的主要优缺点。最后,结合空间谱估计实际工程化的应用需求,指出了高效超分辨算法的未来发展趋势。

  4. Research on an estimation method of DOA for wireless location based on TD-SCDMA

    Science.gov (United States)

    Zhang, Yi; Luo, Yuan; Cheng, Shi-xin

    2004-03-01

    To meet the urgent need of personal communication and hign-speed data services,the standardization and products development for International Mobile Telecommunication-2000 (IMT-2000) have become a hot point in wordwide. The wireless location for mobile terminals has been an important research project. Unlike GPS which is located by 24 artificial satellities, it is based on the base-station of wireless cell network, and the research and development of it are correlative with IMT-2000. While the standard for the third generation mobile telecommunication (3G)-TD-SCDMA, which is proposed by China and the intellective property right of which is possessed by Chinese, is adopted by ITU-T at the first time, the research for wireless location based on TD-SCDMA has theoretic meaning, applied value and marketable foreground. First,the basic principle and method for wireless location, i.e. Direction of Angle(DOA), Time of Arrival(TOA) or Time Difference of Arrival(TDOA), hybridized location(TOA/DOA,TDOA/DOA,TDOA/DOA),etc. is introduced in the paper. So the research of DOA is very important in wireless location. Next, Main estimation methods of DOA for wireless location, i.e. ESPRIT, MUSIC, WSF, Min-norm, etc. are researched in the paper. In the end, the performances of DOA estimation for wireless location based on mobile telecommunication network are analyzed by the research of theory and simulation experiment and the contrast algorithms between and Cramer-Rao Bound. Its research results aren't only propitious to the choice of algorithms for wireless location, but also to the realization of new service of wireless location .

  5. A low-complexity joint 2D-DOD and 2D-DOA estimation algorithm for MIMO radar with arbitrary arrays

    Science.gov (United States)

    Chen, Chen; Zhang, Xiaofei

    2013-10-01

    In this article, we study the problem of four-dimensional angles estimation for bistatic multiple-input multiple-output (MIMO) radar with arbitrary arrays, and propose a joint two-dimensional direction of departure (2D-DOD) and two-dimensional direction of arrival (2D-DOA) estimation algorithm. Our algorithm is to extend the propagator method (PM) for angle estimation in MIMO radar. The proposed algorithm does not require peak searching and eigenvalue decomposition of received signal covariance matrix, because of this, it has low computational complexity. And it can achieve automatic pairing of four-dimensional angles. Furthermore, the proposed algorithm has much better angle estimation performance than interpolated estimation method of signal parameters via rotational invariance techniques (ESPRIT), and has very close angle estimation performance to ESPRIT-like algorithm which has higher computational cost than the proposed algorithm. We also analyze the complexity and angle estimation error of the algorithm, and derive the Cramer-Rao bound (CRB). The simulation results verify the effectiveness and improvement of the proposed algorithm.

  6. Research on Modified Root-MUSIC Algorithm of DOA Estimation Based on Covariance Matrix Reconstruction

    Directory of Open Access Journals (Sweden)

    Changgan SHU

    2014-09-01

    Full Text Available In the standard root multiple signal classification algorithm, the performance of direction of arrival estimation will reduce and even lose effect in circumstances that a low signal noise ratio and a small signals interval. By reconstructing and weighting the covariance matrix of received signal, the modified algorithm can provide more accurate estimation results. The computer simulation and performance analysis are given next, which show that under the condition of lower signal noise ratio and stronger correlation between signals, the proposed modified algorithm could provide preferable azimuth estimating performance than the standard method.

  7. 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.

  8. A new DOD and DOA estimation method for MIMO radar

    Science.gov (United States)

    Gong, Jian; Lou, Shuntian; Guo, Yiduo

    2018-04-01

    The battlefield electromagnetic environment is becoming more and more complex, and MIMO radar will inevitably be affected by coherent and non-stationary noise. To solve this problem, an angle estimation method based on oblique projection operator and Teoplitz matrix reconstruction is proposed. Through the reconstruction of Toeplitz, nonstationary noise is transformed into Gauss white noise, and then the oblique projection operator is used to separate independent and correlated sources. Finally, simulations are carried out to verify the performance of the proposed algorithm in terms of angle estimation performance and source overload.

  9. An efficient central DOA tracking algorithm for multiple incoherently distributed sources

    Science.gov (United States)

    Hassen, Sonia Ben; Samet, Abdelaziz

    2015-12-01

    In this paper, we develop a new tracking method for the direction of arrival (DOA) parameters assuming multiple incoherently distributed (ID) sources. The new approach is based on a simple covariance fitting optimization technique exploiting the central and noncentral moments of the source angular power densities to estimate the central DOAs. The current estimates are treated as measurements provided to the Kalman filter that model the dynamic property of directional changes for the moving sources. Then, the covariance-fitting-based algorithm and the Kalman filtering theory are combined to formulate an adaptive tracking algorithm. Our algorithm is compared to the fast approximated power iteration-total least square-estimation of signal parameters via rotational invariance technique (FAPI-TLS-ESPRIT) algorithm using the TLS-ESPRIT method and the subspace updating via FAPI-algorithm. It will be shown that the proposed algorithm offers an excellent DOA tracking performance and outperforms the FAPI-TLS-ESPRIT method especially at low signal-to-noise ratio (SNR) values. Moreover, the performances of the two methods increase as the SNR values increase. This increase is more prominent with the FAPI-TLS-ESPRIT method. However, their performances degrade when the number of sources increases. It will be also proved that our method depends on the form of the angular distribution function when tracking the central DOAs. Finally, it will be shown that the more the sources are spaced, the more the proposed method can exactly track the DOAs.

  10. High Resolution DOA Estimation Based on Sparse Reconstruction of Delay Correlation Function%基于延时相关的稀疏恢复高分辨来波方位估计

    Institute of Scientific and Technical Information of China (English)

    谢前朋; 王伦文

    2016-01-01

    针对 MUSIC 算法和基于四阶累积量的 MUSIC-like 算法在高斯色噪声背景下测向精度不理想的问题,提出基于延时相关的稀疏恢复高分辨来波方位估计算法。该算法利用蕴含在接收数据延时相关函数中的角度信息,采用所有阵元接收数据的延时相关函数构造新的阵列输出矩阵,进而构造新的协方差矩阵,并进行奇异值分解,建立稀疏表示模型,使用l1范数法对稀疏模型进行求解实现色噪声环境下高分辨 DOA估计。仿真实验表明,基于延时相关的稀疏表示模型的测向分辨率好于基于传统子空间的 MUSIC 算法和基于四阶累积量的 MUSIC-like算法,能降低协方差构造的复杂度,增强色噪声抑制能力。%In order to solve theproblem of angular precision of DOA estimation of MUSIC algorithm and MU-SIC-like algorithm in the background of Gaussian color noise,an approach for high resolution DOA estimation based on sparse reconstruction of the delay correlation function of the received data preprocessing was proposed. The proposed algorithm made full use of the information of the direction of arrival contained in the delay correla-tion function and used the delay correlation function of all the received data to construct a new array matrix,then through the singular value decomposition to construct the sparse representation model and using l1 norm algo-rithm to realize high resolution DOA estimation in the background of Gaussian color noise.The proposed algo-rithm had lower covariance computational complexity and good ability to restrain Gaussian color noise.Experi-mental results showed that the resolution DOA estimation of sparse representation model based on time delay correlation function had a better performance than MUSIC algorithm based on the traditional subspace and MU-SIC-like algorithm based on fourth-order cumulant.

  11. Low-complexity DOA estimation from short data snapshots for ULA systems using the annihilating filter technique

    Science.gov (United States)

    Bellili, Faouzi; Amor, Souheib Ben; Affes, Sofiène; Ghrayeb, Ali

    2017-12-01

    This paper addresses the problem of DOA estimation using uniform linear array (ULA) antenna configurations. We propose a new low-cost method of multiple DOA estimation from very short data snapshots. The new estimator is based on the annihilating filter (AF) technique. It is non-data-aided (NDA) and does not impinge therefore on the whole throughput of the system. The noise components are assumed temporally and spatially white across the receiving antenna elements. The transmitted signals are also temporally and spatially white across the transmitting sources. The new method is compared in performance to the Cramér-Rao lower bound (CRLB), the root-MUSIC algorithm, the deterministic maximum likelihood estimator and another Bayesian method developed precisely for the single snapshot case. Simulations show that the new estimator performs well over a wide SNR range. Prominently, the main advantage of the new AF-based method is that it succeeds in accurately estimating the DOAs from short data snapshots and even from a single snapshot outperforming by far the state-of-the-art techniques both in DOA estimation accuracy and computational cost.

  12. Joint 2D-DOA and Frequency Estimation for L-Shaped Array Using Iterative Least Squares Method

    Directory of Open Access Journals (Sweden)

    Ling-yun Xu

    2012-01-01

    Full Text Available We introduce an iterative least squares method (ILS for estimating the 2D-DOA and frequency based on L-shaped array. The ILS iteratively finds direction matrix and delay matrix, then 2D-DOA and frequency can be obtained by the least squares method. Without spectral peak searching and pairing, this algorithm works well and pairs the parameters automatically. Moreover, our algorithm has better performance than conventional ESPRIT algorithm and propagator method. The useful behavior of the proposed algorithm is verified by simulations.

  13. 基于超声阵列传感器与遗传MUSIC的局放源波达方向估计%Source DOA Estimation Based on Ultrasonic Array Sensor and Genetic MUSIC

    Institute of Scientific and Technical Information of China (English)

    侯姗姗; 谢庆; 廖峰; 纪巍

    2014-01-01

    基于超声阵列传感器的局放源波达方向估计是局部放电准确定位的基础。传统MUSIC测向算法的精度和搜索成功率较低,据此提出一种基于超声阵列传感器与遗传MUSIC算法的局放源波达方向估计新方法。遗传MUSIC算法利用空间谱估计公式构造适应度函数,基于遗传迭代搜索的思想对方位角进行谱峰搜索,以获得全局最优解。通过建立信号模型、阵列模型开展了大量仿真实验,并采用寻优精度、搜索成功率和搜索时间等三个指标为依据,对经典MUSIC和遗传MUSIC的测向结果进行对比。结果表明,基于遗传MUSIC算法提高了搜索成功率,绝对精度相较传统MUSIC算法误差减小0.3°,可以获得更高精度的局放源波达方向角。%Partial discharge direction of arrival ( DOA) estimation based on ultrasonic array sensor is the basis for ac-curate positioning of the partial discharge. Considering the problem of low precision and searching success rate of tra-ditional MUSIC direction finding algorithm, the paper presents a new method based on ultrasonic array sensor and ge-netic MUSIC algorithm for partial discharge DOA estimation. The genetic MUSIC algorithm constructs fitness function with spatial spectrum estimation, and searches spectral peak of the azimuth based on the idea of genetic iterative searching for global optimal solution. This paper carried out a large number of simulation experiments through the es-tablishment of signal model and array model, then uses three indicators of searching precision, searching success rate and searching time as the basis to compare the direction finding results of classical MUSIC and genetic MUSIC. Re-sults show that compared with traditional MUSIC algorithm, the genetic MUSIC based algorithm improves the searching success rate and reduces the error by 0. 3° in absolute precision, therefore obtains higher accuracy of partial discharge DOA angle.

  14. 极化敏感阵列的DOA及极化参数降维估计算法%Dimension-reduction for DOA and polarization estimation based on polarization sensitive array

    Institute of Scientific and Technical Information of China (English)

    曾富红; 曲志昱; 司伟建

    2017-01-01

    为解决极化MUSIC算法运算量大的问题,提出了一种适用于极化敏感阵列的秩亏损MUSIC算法.在极化MUSIC算法的基础上,通过运用矩阵秩亏损原理将谱函数进行降维优化成只与空域参数相关的二维谱函数,大大降低了谱峰搜索过程中的运算量,同时保证了波达方向(DOA)估计精度.在获得入射信号的DOA之后,通过公式可直接计算得到入射信号的极化参数,具有较低的运算量.通过仿真实验可以验证秩亏损MUSIC算法存在着较高的估计精度,并通过将其与极化MUSIC算法的计算复杂度进行对比,可以发现秩亏损MUSIC算法具有较好的实时性,在入射信号相同并含有极化信息的条件下,秩亏损MUSIC算法的计算复杂度相较于极化MUSIC算法降低了104数量级.%To solve the problem that polarization MUSIC algorithm has large computational complexity, a rank loss MUSIC algorithm suitable for polarization sensitive array was proposed.On the basis of polarization MUSIC algorithm, using the principle of matrix rank loss to reduce the dimensionality of the spectral function to two-dimensional spectral function related to the airspace parameters, the computation significantly was decreased but also guarantees the direction of arrival(DOA) estimation accuracy.After getting the DOA of the incident signal, the polarization parameters can be directly calculated by formula which has low computational complexity.Simulation results show that the proposed algorithm has high estimation precision.The proposed algorithm has better real-time performance compared with that polarization MUSIC algorithm.

  15. Joint angle and Doppler frequency estimation of coherent targets in monostatic MIMO radar

    Science.gov (United States)

    Cao, Renzheng; Zhang, Xiaofei

    2015-05-01

    This paper discusses the problem of joint direction of arrival (DOA) and Doppler frequency estimation of coherent targets in a monostatic multiple-input multiple-output radar. In the proposed algorithm, we perform a reduced dimension (RD) transformation on the received signal first and then use forward spatial smoothing (FSS) technique to decorrelate the coherence and obtain joint estimation of DOA and Doppler frequency by exploiting the estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm. The joint estimated parameters of the proposed RD-FSS-ESPRIT are automatically paired. Compared with the conventional FSS-ESPRIT algorithm, our RD-FSS-ESPRIT algorithm has much lower complexity and better estimation performance of both DOA and frequency. The variance of the estimation error and the Cramer-Rao Bound of the DOA and frequency estimation are derived. Simulation results show the effectiveness and improvement of our algorithm.

  16. Efficient method for location and detection of partial discharge in transformer oil by DOA estimation of circular array of ultrasonic sensors

    Science.gov (United States)

    Saravanakumar, N.; Sathiyasekar, K.

    2018-01-01

    The electrical insulation failures in oil transformers are mainly occurs due to the inappropriate placing of Partial Discharge (PD) sources. In order to eliminate the insulation defects and also to locate the PD sources in an appropriate location, a new approach called circular array of ultrasonic sensors (CAUS) with various analysis is proposed. At first de-noise the PD signal from the CAUS using the fast independent component analysis (Fast ICA) algorithm. Secondly, the wide band signal from CAUS is converted into narrow band signal by using the total least square algorithm (TLS). Third, parse representation of array covariance vector (SRACV) technique is utilized to separate DOA (Direction of Arrival) in three directions from PD to CAUS. Finally, the PD sources are placed in an appropriate location by using the pitch and azimuth angles of those three DOAs and the exact coordination of three planes are calculated by using the particle swarm optimization algorithm. The simulation result demonstrates the effectiveness of proposed approach in terms of PD location in transformer oil.

  17. Joint DOA and Fundamental Frequency Estimation Methods based on 2-D Filtering

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2010-01-01

    of the fundamental frequency and the DOA of spatio-temporarily sampled periodic signals. The first and simplest method is based on the 2-D periodogram, whereas the second method is a generalization of the 2-D Capon method. In the experimental part, both qualitative and quantitative measurements show that the proposed...

  18. Method for Establishing Direction of Arrival by Use of Signals of Opportunity

    Science.gov (United States)

    2017-08-29

    digital converter (ADC). The analog-to-digital converter sampling process that locks the relative time features of the digital signal processing...path and is sampled by the ADC. The ADC sampling process locks the relative time properties of the individual signals components arriving at...that signal. For each wave vector, the angles that define the direction of arrival are assumed to be identical at each RF port phase center in the

  19. Parameter Estimation of Multiple Frequency-Hopping Signals with Two Sensors

    Directory of Open Access Journals (Sweden)

    Le Zuo

    2018-04-01

    Full Text Available This paper essentially focuses on parameter estimation of multiple wideband emitting sources with time-varying frequencies, such as two-dimensional (2-D direction of arrival (DOA and signal sorting, with a low-cost circular synthetic array (CSA consisting of only two rotating sensors. Our basic idea is to decompose the received data, which is a superimposition of phase measurements from multiple sources into separated groups and separately estimate the DOA associated with each source. Motivated by joint parameter estimation, we propose to adopt the expectation maximization (EM algorithm in this paper; our method involves two steps, namely, the expectation-step (E-step and the maximization (M-step. In the E-step, the correspondence of each signal with its emitting source is found. Then, in the M-step, the maximum-likelihood (ML estimates of the DOA parameters are obtained. These two steps are iteratively and alternatively executed to jointly determine the DOAs and sort multiple signals. Closed-form DOA estimation formulae are developed by ML estimation based on phase data, which also realize an optimal estimation. Directional ambiguity is also addressed by another ML estimation method based on received complex responses. The Cramer-Rao lower bound is derived for understanding the estimation accuracy and performance comparison. The verification of the proposed method is demonstrated with simulations.

  20. Reduced complexity FFT-based DOA and DOD estimation for moving target in bistatic MIMO radar

    KAUST Repository

    Ali, Hussain; Ahmed, Sajid; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2016-01-01

    classification (2D-MUSIC) and reduced-dimension MUSIC (RD-MUSIC) algorithms. It is shown by simulations, our proposed algorithm has better estimation performance and lower computational complexity compared to the 2D-MUSIC and RD-MUSIC algorithms. Moreover

  1. Root-MUSIC Based Angle Estimation for MIMO Radar with Unknown Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Jianfeng Li

    2014-01-01

    Full Text Available Direction of arrival (DOA estimation problem for multiple-input multiple-output (MIMO radar with unknown mutual coupling is studied, and an algorithm for the DOA estimation based on root multiple signal classification (MUSIC is proposed. Firstly, according to the Toeplitz structure of the mutual coupling matrix, output data of some specified sensors are selected to eliminate the influence of the mutual coupling. Then the reduced-dimension transformation is applied to make the computation burden lower as well as obtain a Vandermonde structure of the direction matrix. Finally, Root-MUSIC can be adopted for the angle estimation. The angle estimation performance of the proposed algorithm is better than that of estimation of signal parameters via rotational invariance techniques (ESPRIT-like algorithm and MUSIC-like algorithm. Furthermore, the proposed algorithm has lower complexity than them. The simulation results verify the effectiveness of the algorithm, and the theoretical estimation error of the algorithm is also derived.

  2. Efficient DoA Tracking of Variable Number of Moving Stochastic EM Sources in Far-Field Using PNN-MLP Model

    Directory of Open Access Journals (Sweden)

    Zoran Stanković

    2015-01-01

    Full Text Available An efficient neural network-based approach for tracking of variable number of moving electromagnetic (EM sources in far-field is proposed in the paper. Electromagnetic sources considered here are of stochastic radiation nature, mutually uncorrelated, and at arbitrary angular distance. The neural network model is based on combination of probabilistic neural network (PNN and the Multilayer Perceptron (MLP networks and it performs real-time calculations in two stages, determining at first the number of moving sources present in an observed space sector in specific moments in time and then calculating their angular positions in azimuth plane. Once successfully trained, the neural network model is capable of performing an accurate and efficient direction of arrival (DoA estimation within the training boundaries which is illustrated on the appropriate example.

  3. DOAS urban pollution measurements

    International Nuclear Information System (INIS)

    Stevens, R.K.; Vossler, T.L.

    1991-01-01

    This paper reports that during July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc., was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 and path 2, ozone (O 3 ), sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), nitrous acid (HNO 2 ), formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH 3 ) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Data quality criteria for each compound were chosen such that the average relative standard deviation would be less than 25%. Data capture ranged from 43% for o-xylene for path 1 to 95% for ozone for path 2. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRM) instruments were located near the DOAS light receivers and measurements of O 3 , NO 2 , and NO were made concurrently with the DOAS. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's; however, there was a difference between the mean values obtained by the two methods for O 3 and NO. A gas chromatograph for measuring volatile organic compounds was operated next to the FRM's. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o-xylene

  4. Parallel Factor-Based Model for Two-Dimensional Direction Estimation

    Directory of Open Access Journals (Sweden)

    Nizar Tayem

    2017-01-01

    Full Text Available Two-dimensional (2D Direction-of-Arrivals (DOA estimation for elevation and azimuth angles assuming noncoherent, mixture of coherent and noncoherent, and coherent sources using extended three parallel uniform linear arrays (ULAs is proposed. Most of the existing schemes have drawbacks in estimating 2D DOA for multiple narrowband incident sources as follows: use of large number of snapshots, estimation failure problem for elevation and azimuth angles in the range of typical mobile communication, and estimation of coherent sources. Moreover, the DOA estimation for multiple sources requires complex pair-matching methods. The algorithm proposed in this paper is based on first-order data matrix to overcome these problems. The main contributions of the proposed method are as follows: (1 it avoids estimation failure problem using a new antenna configuration and estimates elevation and azimuth angles for coherent sources; (2 it reduces the estimation complexity by constructing Toeplitz data matrices, which are based on a single or few snapshots; (3 it derives parallel factor (PARAFAC model to avoid pair-matching problems between multiple sources. Simulation results demonstrate the effectiveness of the proposed algorithm.

  5. A New DOA Algorithm Based on Nonlinear Compress Core Function in Symmetric α-stable Distribution Noise Environment%一种对称琢稳定分布噪声环境下DOA估计新算法

    Institute of Scientific and Technical Information of China (English)

    马金全; 葛临东; 童莉

    2014-01-01

    脉冲噪声环境下波达方向( DOA)估计是阵列信号处理领域一个新兴研究方向。针对α稳定分布噪声环境下经典MUSIC算法性能退化的问题,提出了一种新的基于非线性压缩核函数( NCCF)的DOA估计算法。该算法利用基于NCCF的有界矩阵代替了MUSIC的协方差矩阵,通过对有界矩阵进行特征分解确定信号子空间和噪声子空间,借用MUSIC谱估计公式进行谱峰搜索,得到DOA的估计值。仿真结果表明,NCCF-MUSIC算法运算复杂度较低,相比于基于分数低阶统计量( FLOS)的MUSIC方法和基于广义类相关熵( GCAS)的MUSIC算法,该方法具有更好的准确度和稳定性。%Direction of arrival ( DOA) estimation in the impulse noise environment is a new research direc-tion in the array signal processing field. To solve the problem of performance degradation when applying classic MUSIC algorithm for DOA estimation in the α-stable distribution noise environment,a novel DOA estimation algorithm based on a nonlinear compress core function ( NCCF ) is provided and named as the NCCF-MUSIC. To obtain a DOA estimation,the NCCF-MUSIC method replaces the covariance matrix in MUSIC by a bounded matrix based on the NCCF,and then determines the signal subspace and the noise subspace by feature decomposition, and finally, introduces the MUSIC spectrum estimation algorithm to make a spectral peak searching. Simulation results show that the new NCCF-MUSIC method with a lower computation cost has the higher performance in accuracy and validity than the MUSIC methods based on fractional lower order statistics ( FLOS) or based on generalized correntropy-analogous statistics ( GCAS) .

  6. 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

  7. Estimation of the Paris NOx emissions from mobile MAX-DOAS observations and CHIMERE model simulations during the MEGAPOLI campaign using the closed integral method

    Science.gov (United States)

    Shaiganfar, Reza; Beirle, Steffen; Denier van der Gon, Hugo; Jonkers, Sander; Kuenen, Jeroen; Petetin, Herve; Zhang, Qijie; Beekmann, Matthias; Wagner, Thomas

    2017-06-01

    We determined NOx emissions from Paris in summer 2009 and winter 2009/2010 by applying the closed integral method (CIM) to a large set of car multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements performed within the framework of the MEGAPOLI project (dk/" target="_blank">http://megapoli.dmi.dk/). MAX-DOAS measurements of the tropospheric NO2 vertical column density (VCD) were performed in large circles around Paris. From the combination of the observed NO2 VCDs with wind fields, the NO2 influx into and the outflux from the encircled area was determined. The difference between the influx and outflux represents the total emission. Compared to previous applications of the CIM, the large number of measurements during the MEGAPOLI campaign allowed the investigation of important aspects of the CIM. In particular, the applicability of the CIM under various atmospheric conditions could be tested. Another important advantage of the measurements during MEGAPOLI is that simultaneous atmospheric model simulations with a high spatial resolution (3 × 3 km2) are available for all days. Based on these model data, it was possible to test the consistency of the CIM and to derive information about favourable or non-favourable conditions for the application of the CIM. We found that in most situations the uncertainties and the variability in the wind data dominate the total error budget, which typically ranges between 30 and 50 %. Also, measurement gaps and uncertainties in the partitioning ratio between NO and NO2 are important error sources. Based on a consistency check, we deduced a set of criteria on whether measurement conditions are suitable or not for the application of the CIM. We also developed a method for the calculation of the total error budget of the derived NOx emissions. Typical errors are between ±30 and ±50 % for individual days (with one full circle around Paris). From the application of the CIM to car MAX-DOAS observations we derive

  8. 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.

  9. Application of Modified MUSIC Algoritm in DOA Estimation of Coherent Signals%修正的MUSIC算法在相干信源DOA估计中的应用

    Institute of Scientific and Technical Information of China (English)

    赵世峰; 田梅

    2007-01-01

    引用了两种修正相关矩阵最大似然(ML)估计的方法对MUSIC算法进行优化,对相干信源的波达方向(DOA)进行估计.前向空间平滑算法要求阵列的平移不变性,将阵列划分为若干相互交叠的子阵;前向-后向空间平滑要求阵列的旋转不变性,应用了相关矩阵的倒置矩阵.两种方法均可以修正阵列接收信号的相关矩阵的最大似然估计,使之满足MU-SIC算法的前提条件.计算机仿真证明两种算法改善了传统的MUSIC算法对相干信源进行DOA估计的性能,前向-后向空间平滑算法作出了比较准确地估计.

  10. Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar

    Directory of Open Access Journals (Sweden)

    Shouguo Yang

    2015-12-01

    Full Text Available A novel spatio-temporal 2-dimensional (2-D processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters’ outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD and direction of arrival (DOA, and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results.

  11. Mini MAX-DOAS Measurements of Air Pollutants over China

    Science.gov (United States)

    Staadt, Steffen; Hao, Nan; Trautmann, Thomas

    2016-08-01

    This study continues the work of Clémer et al., (2010) and is aimed to improve trace gas retrievals with mini MAX-DOAS measurements in Nanjing. Based on that work, aerosol extinction vertical profiles are retrieved using the bePRO inversion algorithm developed by the Royal Belgian Institute for Space Aeronomy (BIRA- IASB). Afterwards, the tropospheric trace gas vertical profiles and vertical column densities (VCDs) are retrieved by applying the optimal estimation method to the O4 MAX-DOAS measurements. The Profiles for N O2 , S O2 , glyoxal, formaldehyde and nitrous acid are obtained with different results and different settings for the DOAS measurement. The AODs show small positive correlation against the AERONET values. For NO2, the retrieval shows reasonable concentrations in winter as opposed to summer and has small positive correlations with GOME-2 data. The SO2 VCDs are not correlated with the GOME-2 data, due to high uncertainties from MAX-DOAS and satellite retrievals, while the vertical mixing ratios (VMR) show good agreement with in-situ data (SORPES) at Nanjing. Nitrous acid shows a maximum in winter and a minimum in summer, while glyoxal has its maximum in August and September.

  12. A unitary ESPRIT scheme of joint angle estimation for MOTS MIMO radar.

    Science.gov (United States)

    Wen, Chao; Shi, Guangming

    2014-08-07

    The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme.

  13. DOA估计算法的一种修正MUSIC算法的研究%Research on modified MUSIC algorithm of DOA estimation

    Institute of Scientific and Technical Information of China (English)

    赵谦; 董民; 梁文娟

    2012-01-01

    传统改进MUSIC算法通过对接收信号协方差矩阵作预处理,使信号协方差矩阵分解得到信号子空间与噪声子空间正交,从而降低噪声的影响.但当信号间隔很小时,随着信噪比的降低,传统改进MUSIC算法已无法分辨出信号.基于此问题提出的修正MUSIC算法在使信号子空间与噪声子空间正交的基础上,充分利用了噪声子空间及其特征值对噪声子空间的修正,进而构造谱峰搜索函数估计出信号.通过仿真实验、证实了在信噪比很低的情况下,信号间隔很小且存在相关信号时,修正MUSIC算法能准确地估计出传统改进MUSIC算法不能估计的信号.%Traditional improved MUSIC algorithm decomposes the signal covariance matrix to make the signals subspace be orthogonal to the noise subspace, so decreases the effect of the noise. But when the signals interval are very small, traditional improved "MUSIC algorithm has been unable to distinguish the signals as the SNR decreases. To this problem, a modified MUSIC is proposed which makes full use of signals subspace and its eigenvalue, on basis of the signals subspace obtained be orthogonal to the noise subspace, construct spectrum search function and then estimate the signals. Through computer simulation, it has been approved that when the signals interval are very small under the condition of the lower SNR and exist the correlated signals, modified MUSIC can estimate the signals accurately that traditional improved MUSIC algorithm can't estimate.

  14. Doa daLam Tradisi Islam Jawa

    Directory of Open Access Journals (Sweden)

    Abdul Wahab Rosyidi

    2012-12-01

    Full Text Available Doa etymologically means request something to God in certain ways. while some ulama define doa is a self statement presence to Allah the Almighty about our weakness, shortages, inabilities, and disgraces, then we ask Allah the Almighty in order the weaknesses, shortages, inabilities, and humiliations are removed and replaced with the strengths, capabilities and a high degree both in human sight and in Allah sight. In the theory needs said, that basically human beings need to feel safe (safety need, and the safety need leads to the two forms, namely: safety needs of life and safety needs of the property. Safety needs emerged as the most important requirement if psychology needs have been fullfilled. this behavior as reflected in the lives of Javanese who always do doa  in the form of slametan ceremony. Slametan aims to achieve slamet (safety, namely a condition in which the events will move smoothly to follow a predetermined path and will not happen misfortunes to just anyone.   Doa Secara etimologi artinya memohon sesuatu kepada Allah SWT dengan cara- cara tertentu. Sedangkan beberapa ulama mendefinisikan doa berarti pernyataan diri ke hadirat Allah SWT tentang kelemahan, kekurangan, ketidakmampuan serta kehinaan kita, kemudian kita memohon sesuatu kepada Allah SWT agar kelemahan, kekurangan, ketidakmampuan serta kehinaan ini diangkat dan digantikan dengan kelebihan, kemampuan serta derajat yang tinggi baik di sisi manusia maupun di sisi-Nya. Dalam teori kebutuhan dikatakan; bahwa pada dasarnya manusia membutuhkan rasa aman (safety need, dan rasa aman itu mengarah pada dua bentuk yakni kebutuhan keamanan jiwa dan keamanan harta. Kebutuhan rasa aman muncul sebagai kebutuhan yang paling penting kalau kebutuhan psikologis telah terpenuhi. Hal tersebut sebagaimana tercermin dalam perilaku hidup orang Jawa yang selalu melakukan Doa dalam bentuk upacara slametan. Slametan bertujuan untuk mencapai keadaan slamet, yaitu suatu keadaan dimana peristiwa

  15. Pengenalan Doa-doa Pendek Melalui Video Animasi Untuk Anak Usia 3-4 Tahun

    OpenAIRE

    Muriana,; Marmawi R; Sutarmanto

    2017-01-01

    Penelitian ini menggunakan metode penelitian tindakan kelas. Sedangkan media yang digunakan adalah video animasi. Tujuan penelitian ini untuk mengetahui pengenalan doa-doa pendek melalui vodeo animasi untuk anak usia 3-4 tahun. Subjek dalam penelitian ini adalah anak yang berjumlah 10 orang, yang terdiri 3 anak laki-laki dan 7 anak perempuan. Lokasi penelitian ini adalah TPA Taman Pena Kabupaten Kubu Raya. Berdasarkan hasil penelitian yang telah dilakukan dan hasil analisis data, maka secara ...

  16. Channel Parameter Estimation for Scatter Cluster Model Using Modified MUSIC Algorithm

    Directory of Open Access Journals (Sweden)

    Jinsheng Yang

    2012-01-01

    Full Text Available Recently, the scatter cluster models which precisely evaluate the performance of the wireless communication system have been proposed in the literature. However, the conventional SAGE algorithm does not work for these scatter cluster-based models because it performs poorly when the transmit signals are highly correlated. In this paper, we estimate the time of arrival (TOA, the direction of arrival (DOA, and Doppler frequency for scatter cluster model by the modified multiple signal classification (MUSIC algorithm. Using the space-time characteristics of the multiray channel, the proposed algorithm combines the temporal filtering techniques and the spatial smoothing techniques to isolate and estimate the incoming rays. The simulation results indicated that the proposed algorithm has lower complexity and is less time-consuming in the dense multipath environment than SAGE algorithm. Furthermore, the estimations’ performance increases with elements of receive array and samples length. Thus, the problem of the channel parameter estimation of the scatter cluster model can be effectively addressed with the proposed modified MUSIC algorithm.

  17. Polarization Smoothing Generalized MUSIC Algorithm with Polarization Sensitive Array for Low Angle Estimation.

    Science.gov (United States)

    Tan, Jun; Nie, Zaiping

    2018-05-12

    Direction of Arrival (DOA) estimation of low-altitude targets is difficult due to the multipath coherent interference from the ground reflection image of the targets, especially for very high frequency (VHF) radars, which have antennae that are severely restricted in terms of aperture and height. The polarization smoothing generalized multiple signal classification (MUSIC) algorithm, which combines polarization smoothing and generalized MUSIC algorithm for polarization sensitive arrays (PSAs), was proposed to solve this problem in this paper. Firstly, the polarization smoothing pre-processing was exploited to eliminate the coherence between the direct and the specular signals. Secondly, we constructed the generalized MUSIC algorithm for low angle estimation. Finally, based on the geometry information of the symmetry multipath model, the proposed algorithm was introduced to convert the two-dimensional searching into one-dimensional searching, thus reducing the computational burden. Numerical results were provided to verify the effectiveness of the proposed method, showing that the proposed algorithm has significantly improved angle estimation performance in the low-angle area compared with the available methods, especially when the grazing angle is near zero.

  18. Replacing the AMOR with the miniDOAS in the ammonia monitoring network in the Netherlands

    NARCIS (Netherlands)

    Berkhout, Augustinus J. C.; Swart, Daan P. J.; Volten, Hester; Gast, Lou F. L.; Haaima, Marty; Verboom, Hans; Stefess, Guus; Hafkenscheid, Theo; Hoogerbrugge, Ronald

    2017-01-01

    In this paper we present the continued development of the miniDOAS, an active differential optical absorption spectroscopy (DOAS) instrument used to measure ammonia concentrations in ambient air. The miniDOAS has been adapted for use in the Dutch National Air Quality Monitoring Network. The miniDOAS

  19. Development of a DOAS System for ToTAL-DOAS Applications with Temperature Control

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Javier A; Frins, Erna, E-mail: jramos@fing.edu.uy [Instituto de Fisica, Facultad de Ingenieria, UdelaR (Uruguay)

    2011-01-01

    The ToTAL -DOAS (Topographic Target Light scattering - Differential optical Absorption Spectroscopy) is a novel atmospheric monitoring technique. The aim of our work has been enhancing a prototype, previously assembled within our research group, adding to it a temperature control and developing specific control software. The whole system offers the possibility of two dimension movement for spectra acquisition with a telescope of a field of view of approximately 0.03{sup 0}, which let in signals in the near-UV and visible spectral range. The enhanced DOAS system is intended to be located on the roof of our faculty building to monitor SO2 and NO2 traces above the city of Montevideo. We are presenting the results of device's characterization.

  20. DOAS (differential optical absorption spectroscopy) urban pollution measurements

    Science.gov (United States)

    Stevens, Robert K.; Vossler, T. L.

    1991-05-01

    During July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc. was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 (1099 m) and path 2 (1824 m), ozone (03), sulfur dioxide (SO2) nitrogen dioxide (NO2), nitrous acid (HNO2) formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH3) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Data quality criteria for each compound were chosen such that the average relative standard deviation would be less than 25%. Data capture ranged from 43% for o-xylene for path 1 to 95% for ozone for path 2. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRN) instruments were located near the DOAS light receivers and measurements of 03, NO2, and NO were made concurrently with the DOAS. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's; however, there was a difference between the mean values obtained by the two methods for 03 and NO. A gas chromatograph for measuring volatile organic compounds was operated next to the FRN's. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o- xylene. However, the correlation coefficient between the DOAS and GC measurements of toluene averaged only 0.15 for the two DOAS measurement paths. The lack of correlation and other factors indicate the possibility of a localized source of toluene near the GC. In general, disagreements between the two measurement methods could be caused by atmospheric inhomogeneities or interferences in the DOAS and other methods.

  1. Spectral studies of ocean water with space-borne sensor SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS

    Directory of Open Access Journals (Sweden)

    M. Vountas

    2007-09-01

    Full Text Available Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm. The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

  2. Fast Estimation Method of Space-Time Two-Dimensional Positioning Parameters Based on Hadamard Product

    Directory of Open Access Journals (Sweden)

    Haiwen Li

    2018-01-01

    Full Text Available The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA and direction of arrival (DOA parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM system, and the Cramer-Rao bound (CRB is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT algorithm and 2D matrix pencil (MP algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.

  3. Examination of temporal and spatial variability of NO2 VCDs measured using mobile-MAX-DOAS in Toronto, Canada.

    Science.gov (United States)

    Davis, Zoe; Baray, Sabour; Khanbabkhani, Aida; Fujs, William; Csukat, Csilla; McLaren, Robert

    2017-04-01

    Mobile-MAX-DOAS is an innovative technique used to estimate pollutant emission rates and validate satellite measurements and air quality models. It is essential to identify and examine factors that can significantly impact the accuracy of this developing technique. Mobile-MAX-DOAS measurements were conducted in Toronto, Canada with a mini-MAX-DOAS instrument mounted (pointing backwards) on top of a car during August and September, 2016. Scattered sunlight spectra were collected every 45 seconds in the continuously repeated sequence of elevation angles of 30o, 30o, 30o, 30o, 40o, 30o, 90o. Tropospheric VCDs were determined using the geometric approximation from DSCDs fitted using a near-noon, low NO2 VCD FRS spectrum. The study goal was to examine the validity of the assumption that VCDs remain relatively constant at each measured location on a driving route encircling an urban area of interest with typical time periods of 1.5-3 hours to estimate emissions and whether driving direction significantly impacts results. NO2 VCD temporal variability was therefore determined by repeating driving routes in both directions in quick succession on multiple days. Strong temporal variability in NO2 VCDs of up to a factor of two were observed for some routes for the same vehicle locations under constant prevailing wind conditions within cities of up to 90 mg m-2hr-1. This work will be used as a baseline experiment to apply this method in other Canadian cities.

  4. Retrieval of tropospheric NO2 using the MAX-DOAS method combined with relative intensity measurements for aerosol correction

    Directory of Open Access Journals (Sweden)

    P. F. Levelt

    2010-10-01

    Full Text Available Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS is a technique to measure trace gas amounts in the lower troposphere from ground-based scattered sunlight observations. MAX-DOAS observations are especially suitable for validation of tropospheric trace gas observations from satellite, since they have a representative range of several kilometers, both in the horizontal and in the vertical dimension. A two-step retrieval scheme is presented here, to derive aerosol corrected tropospheric NO2 columns from MAX-DOAS observations. In a first step, boundary layer aerosols, characterized in terms of aerosol optical thickness (AOT, are estimated from relative intensity observations, which are defined as the ratio of the sky radiance at elevation α and the sky radiance in the zenith. Relative intensity measurements have the advantage of a strong dependence on boundary layer AOT and almost no dependence on boundary layer height. In a second step, tropospheric NO2 columns are derived from differential slant columns, based on AOT-dependent air mass factors. This two-step retrieval scheme was applied to cloud free periods in a twelve month data set of observations in De Bilt, The Netherlands. In a comparison with AERONET (Cabauw site a mean difference in AOT (AERONET minus MAX-DOAS of −0.01±0.08 was found, and a correlation of 0.85. Tropospheric-NO2 columns were compared with OMI-satellite tropospheric NO2. For ground-based observations restricted to uncertainties below 10%, no significant difference was found, and a correlation of 0.88.

  5. Characterisation of Central-African emissions based on MAX-DOAS measurements, satellite observations and model simulations over Bujumbura, Burundi.

    Science.gov (United States)

    Gielen, Clio; Hendrick, Francois; Pinardi, Gaia; De Smedt, Isabelle; Stavrakou, Trissevgeni; Yu, Huan; Fayt, Caroline; Hermans, Christian; Bauwens, Maité; Ndenzako, Eugene; Nzohabonayo, Pierre; Akimana, Rachel; Niyonzima, Sébastien; Müller, Jean-Francois; Van Roozendael, Michel

    2016-04-01

    Central Africa is known for its strong biogenic, pyrogenic, and to a lesser extent anthropogenic emissions. Satellite observations of species like nitrogen dioxide (NO2) and formaldehyde (HCHO), as well as inverse modelling results have shown that there are large uncertainties associated with the emissions in this region. There is thus a need for additional measurements, especially from the ground, in order to better characterise the biomass-burning and biogenic products emitted in this area. We present MAX-DOAS measurements of NO2, HCHO, and aerosols performed in Central Africa, in the city of Bujumbura, Burundi (3°S, 29°E, 850m). A MAX-DOAS instrument has been operating at this location by BIRA-IASB since late 2013. Aerosol-extinction and trace-gases vertical profiles are retrieved by applying the optimal-estimation-based profiling tool bePRO to the measured O4, NO2 and HCHO slant-column densities. The MAX-DOAS vertical columns and profiles are used for investigating the diurnal and seasonal cycles of NO2, HCHO, and aerosols. Regarding the aerosols, the retrieved AODs are compared to co-located AERONET sun photometer measurements for verification purpose, while in the case of NO2 and HCHO, the MAX-DOAS vertical columns and profiles are used for validating GOME-2 and OMI satellite observations. To characterise the biomass-burning and biogenic emissions in the Bujumbura region, the trace gases and aerosol MAX-DOAS retrievals are used in combination to MODIS fire counts/radiative-power and GOME-2/OMI NO2 and HCHO satellite data, as well as simulations from the NOAA backward trajectory model HYSPLIT. First results show that HCHO seasonal variation around local noon is driven by the alternation of rain and dry periods, the latter being associated with intense biomass-burning agricultural activities and forest fires in the south/south-east and transport from this region to Bujumbura. In contrast, NO2 is seen to depend mainly on local emissions close to the city, due

  6. A Comparison of MODIS and DOAS Sulfur Dioxide Measurements of the April 24, 2004 Eruption of Anatahan Volcano, Mariana Islands

    Science.gov (United States)

    Meier, V. L.; Scuderi, L.; Fischer, T.; Realmuto, V.; Hilton, D.

    2006-12-01

    Measurements of volcanic SO2 emissions provide insight into the processes working below a volcano, which can presage volcanic events. Being able to measure SO2 in near real-time is invaluable for the planning and response of hazard mitigation teams. Currently, there are several methods used to quantify the SO2 output of degassing volcanoes. Ground and aerial-based measurements using the differential optical absorption spectrometer (mini-DOAS) provide real-time estimates of SO2 output. Satellite-based measurements, which can provide similar estimates in near real-time, have increasingly been used as a tool for volcanic monitoring. Direct Broadcast (DB) real-time processing of remotely sensed data from NASA's Earth Observing System (EOS) satellites (MODIS Terra and Aqua) presents volcanologists with a range of spectral bands and processing options for the study of volcanic emissions. While the spatial resolution of MODIS is 1 km in the Very Near Infrared (VNIR) and Thermal Infrared (TIR), a high temporal resolution and a wide range of radiance measurements in 32 channels between VNIR and TIR combine to provide a versatile space borne platform to monitor SO2 emissions from volcanoes. An important question remaining to be answered is how well do MODIS SO2 estimates compare with DOAS estimates? In 2004 ground-based plume measurements were collected on April 24th and 25th at Anatahan volcano in the Mariana Islands using a mini-DOAS (Fischer and Hilton). SO2 measurements for these same dates have also been calculated using MODIS images and SO2 mapping software (Realmuto). A comparison of these different approaches to the measurement of SO2 for the same plume is presented. Differences in these observations are used to better quantify SO2 emissions, to assess the current mismatch between ground based and remotely sensed retrievals, and to develop an approach to continuously and accurately monitor volcanic activity from space in near real-time.

  7. Molecular determinants of the interaction between Doa1 and Hse1 involved in endosomal sorting.

    Science.gov (United States)

    Han, Seungsu; Shin, Donghyuk; Choi, Hoon; Lee, Sangho

    2014-03-28

    Yeast Doa1/Ufd3 is an adaptor protein for Cdc48 (p97 in mammal), an AAA type ATPase associated with endoplasmic reticulum-associated protein degradation pathway and endosomal sorting into multivesicular bodies. Doa1 functions in the endosomal sorting by its association with Hse1, a component of endosomal sorting complex required for transport (ESCRT) system. The association of Doa1 with Hse1 was previously reported to be mediated between PFU domain of Doa1 and SH3 of Hse1. However, it remains unclear which residues are specifically involved in the interaction. Here we report that Doa1/PFU interacts with Hse1/SH3 with a moderate affinity of 5 μM. Asn-438 of Doa1/PFU and Trp-254 of Hse1/SH3 are found to be critical in the interaction while Phe-434, implicated in ubiquitin binding via a hydrophobic interaction, is not. Small-angle X-ray scattering measurements combined with molecular docking and biochemical analysis yield the solution structure of the Doa1/PFU:Hse1/SH3 complex. Taken together, our results suggest that hydrogen bonding is a major determinant in the interaction of Doa1/PFU with Hse1/SH3. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. MAX-DOAS formaldehyde slant column measurements during CINDI: intercomparison and analysis improvement

    Directory of Open Access Journals (Sweden)

    G. Pinardi

    2013-01-01

    Full Text Available We present intercomparison results for formaldehyde (HCHO slant column measurements performed during the Cabauw Intercomparison campaign of Nitrogen Dioxide measuring Instruments (CINDI that took place in Cabauw, the Netherlands, in summer 2009. During two months, nine atmospheric research groups simultaneously operated MAX-DOAS (MultiAXis Differential Optical Absorption Spectroscopy instruments of various designs to record UV-visible spectra of scattered sunlight at different elevation angles that were analysed using common retrieval settings. The resulting HCHO data set was found to be highly consistent, the mean difference between instruments generally not exceeding 15% or 7.5 × 1015 molec cm−2, for all viewing elevation angles. Furthermore, a sensitivity analysis was performed to investigate the uncertainties in the HCHO slant column retrieval when varying key input parameters such as the molecular absorption cross sections, correction terms for the Ring effect or the width and position of the fitting interval. This study led to the identification of potentially important sources of errors associated with cross-correlation effects involving the Ring effect, O4, HCHO and BrO cross sections and the DOAS closure polynomial. As a result, a set of updated recommendations was formulated for HCHO slant column retrieval in the 336.5–359 nm wavelength range. To conclude, an error budget is proposed which distinguishes between systematic and random uncertainties. The total systematic error is estimated to be of the order of 20% and is dominated by uncertainties in absorption cross sections and related spectral cross-correlation effects. For a typical integration time of one minute, random uncertainties range between 5 and 30%, depending on the noise level of individual instruments.

  9. MAX-DOAS measurements of NO2 column densities in Vienna

    Science.gov (United States)

    Schreier, Stefan; Weihs, Philipp; Peters, Enno; Richter, Andreas; Ostendorf, Mareike; Schönhardt, Anja; Burrows, John P.; Schmalwieser, Alois

    2017-04-01

    In the VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols) project, two Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) systems will be set up at two different locations and altitudes in Vienna, Austria. After comparison measurements in Bremen, Germany, and Cabauw, The Netherlands, the first of the two MAX-DOAS instruments was set up at the University of Veterinary Medicine in the northeastern part of Vienna in December 2016. The instrument performs spectral measurements of visible scattered sunlight at defined horizontal and vertical viewing directions. From these measurements, column densities of NO2 and aerosols are derived by applying the DOAS analysis. First preliminary results are presented. The second MAX-DOAS instrument will be set up in April/May 2017 at the University of Natural Resources and Life Sciences in the northwestern part of Vienna. Once these two instruments are measuring simultaneously, small campaigns including car DOAS zenith-sky and tower DOAS off-axis measurements are planned. The main emphasis of this project will be on the installation and operation of two MAX-DOAS instruments, the improvement of tropospheric NO2 and aerosol retrieval, and the characterization of the horizontal, vertical, and temporal variations of tropospheric NO2 and aerosols in Vienna, Austria.

  10. Accounting for surface reflectance in the derivation of vertical column densities of NO2 from airborne imaging DOAS

    Science.gov (United States)

    Meier, Andreas Carlos; Schönhardt, Anja; Richter, Andreas; Bösch, Tim; Seyler, André; Constantin, Daniel Eduard; Shaiganfar, Reza; Merlaud, Alexis; Ruhtz, Thomas; Wagner, Thomas; van Roozendael, Michel; Burrows, John. P.

    2016-04-01

    the derivation of air mass factors used to convert the measurements into vertical columns. Due to the high-resolution measurements, no data product of surface reflectance with sufficient spatial resolution is available. Thus the surface reflectance is estimated from AirMAP's own spectra. In this work the results of the research flights will be presented. The study focuses on the validation of AirMAP's measurements by comparison to other ground-based platforms like (mobile) MAX-DOAS measurements. Conclusions will be drawn on the quality of the measurements, their applicability for satellite data validation and possible improvements for future measurements.

  11. Comparison of stratospheric NO2 profiles above Kiruna, Sweden retrieved from ground-based zenith sky DOAS measurements, SAOZ balloon measurements and SCIAMACHY limb observations

    Science.gov (United States)

    Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Pukite, Janis; Van Roozendael, Michel; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

    2015-04-01

    Stratospheric NO2 not only destroys ozone but acts as a buffer against halogen catalyzed ozone loss by converting halogen species into stable nitrates. These two roles of stratospheric NO2 depend on the altitude. Hence, the objective of this study is to investigate the vertical distribution of stratospheric NO2. We compare the NO2 profiles derived from the zenith sky DOAS with those obtained from, SAOZ balloon measurements and satellite limb observations. Vertical profiles of stratospheric NO2 are retrieved from ground-based zenith sky DOAS observations operated at Kiruna, Sweden (68.84°N, 20.41°E) since 1996. To determine the profile of stratospheric NO2 measured from ground-based zenith sky DOAS, we apply the Optimal Estimation Method (OEM) to retrieval of vertical profiles of stratospheric NO2 which has been developed by IASB-BIRA. The basic principle behind this profiling approach is the dependence of the mean scattering height on solar zenith angle (SZA). We compare the retrieved profiles to two additional datasets of stratospheric NO2 profile. The first one is derived from satellite limb observations by SCIAMACHY (Scanning Imaging Absorption spectrometer for Atmospheric CHartographY) on EnviSAT. The second is derived from the SAOZ balloon measurements (using a UV/Visible spectrometer) performed at Kiruna in Sweden.

  12. 3 dimensional distributions of NO2, CHOCHO, and HCHO measured by the University of Colorado 2D-MAX-DOAS during MAD-CAT

    Science.gov (United States)

    Ortega, Ivan; Sinreich, Roman; Volkamer, Rainer

    2014-05-01

    We present results of 2 dimensional Multi Axis-DOAS (2D-MAX-DOAS) measurements to infer 3-dimensional measurements of trace gases by characterizing boundary layer vertical profiles and near surface azimuth horizontal distribution of NO2 (14 angles covering 360°). We combine the established optimal estimation inversion with a new parameterization approach; the first method to derive NO2 tropospheric vertical profiles and boundary layer height and the second one to retrieve the azimuth horizontal distribution of near surface NO2 mixing ratios, both at multiple wavelengths (350 nm, 450 nm, and 560 nm). This was conducted for three cloud-free days in the framework of the intensive Multi Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany 2013. By retrieving NO2 at multiple wavelengths range-resolved distributions of NO2 are derived using an 'Onion-peeling' approach, i.e., exploiting the fact that the optical path lengths at different wavelengths probe different horizontal air masses. We also measure glyoxal (CHOCHO) and formaldehyde (HCHO) distributions, and present to our knowledge the first 3-dimesional trace-gas distribution measurements of CHOCHO by a ground-based instrument. We expand the 2D-MAX-DOAS capabilities to calculate azimuth ratios of HCHO-to-NO2 (RFN) and CHOCHO-to-NO2 (RGN) to pinpoint volatile organic compound (VOC) oxidation chemistry and CHOCHO-to-HCHO (RGF) ratios as an indicator of biogenic and/or anthropogenic VOC emissions. The results of RFN correlate well with RGN and we identify azimuth variations that indicate gradients in the VOC/NOx chemistry that leads to O3 and secondary aerosol production. While there is a clear diurnal pattern in the RFN and RGN, no such variations are observed in the RGF, which shows rather constant values below 0.04 throughout the day, consistent with previous measurements, and indicative of urban air masses.

  13. The role of the Drosophila LAMMER protein kinase DOA in somatic ...

    Indian Academy of Sciences (India)

    2010-09-06

    Sep 6, 2010 ... Somatic sexual identity in Drosophila melanogaster is under the control of a ... between stages 12 and 14, in response to an X to autosome .... MER kinases used were Drosophila DOA, mouse CLK1, human CLK2 and.

  14. Five years of NO2 Mobile-DOAS measurements in Europe: an overview

    Science.gov (United States)

    Merlaud, Alexis; Fayt, Caroline; Pinardi, Gaia; Tack, Frederik; Hendrick, François; Le Roux, Anabel-Lise; Constantin, Daniel-Eduard; Voiculescu, Mirela; Shaiganfar, Reza; Wagner, Thomas; Van Roozendael, Michel

    2014-05-01

    Since the CINDI campaign held in the Netherlands in July 2009, BIRA-IASB has been operating a car-based mobile-DOAS system, primarily dedicated to tropospheric NO2 measurements. The instrument is based on two similar compact spectrometers and records scattered light spectra simultaneously in the zenith direction and 30° above the horizon, following the MAX-DOAS approach. After CINDI, Mobile-DOAS measurements were performed on a routine basis between March 2010 and August 2011, mostly across Belgium, but also in Luxembourg, France, and Germany. From 2011, another BIRA-IASB mobile-DOAS instrument, using a single zenith channel, was operated in Romania through a collaboration with the University of Galati. In June 2013, these two mobile-DOAS instruments took part in the MADCAT campaign in Mainz, Germany, together with the MPIC mobile-DOAS system, based on a mini MAX-DOAS. We describe the BIRA-IASB instruments, our strategy to retrieve the NO2 tropospheric column, and the large database that was constituted. The latter is particularly interesting for its size: it covers some 500 hours of measurements and 20 000 km, including rural, periurban and urban areas with different air quality conditions. A 2011 cloud-free subset of the measurements is compared with OMI data. We also present preliminary results of an intercomparison between the three mobile-DOAS instruments operated during MADCAT. The high spatial frequency of the measurements (around 100 m) makes them valuable to study the NO2 horizontal gradients in polluted areas. This has implications in the context of air quality satellite validation studies, in which the variability of NO2 inside a satellite pixel must be taken into account.

  15. Multi-year MAX-DOAS observations of formaldehyde and glyoxal in Phimai, Thailand

    Science.gov (United States)

    Hoque, H. M. S.; Irie, H.; Shimizu, A.; Damiani, A.

    2017-12-01

    The first long-term Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations were performed in Phimai, Thailand (15.18 °N, 102.56 °E), a site in Southeast Asia, where ground-based remote sensing observations of trace gases and aerosols are very limited. Vertical profile information of eight components was retrieved independently using the Japanese MAX-DOAS profile retrieval algorithm, version 2 (JM2). Here we focus on the two organic compounds, formaldehyde (HCHO) and glyoxal (CHOCHO), and study their volume mixing ratio data in the lowest layer (0-1 km) of our retrieved vertical profiles. In addition to the systematic climatological analysis of HCHO and CHOCHO, we also report the ratio of CHOCHO to HCHO, RGF, which is suggested to be an important tracer of changes of the volatile organic compound (VOC) emission sources. Higher concentration of HCHO and CHOCHO was observed during the dry season (January-April), whereas the concentration level was close to the background level during the wet season (June-September). Such enhancements correspond well the influence of the pronounced seasonal variation of biomass burning activity. The RGF for the Phimai site was estimated to be 0.030±0.010. Our estimated RGF during the dry season ( 0.025±0.008) was lower than that in the wet season ( 0.033±0.012). This change in the RGF is consistent with the satellite retrievals, suggesting a higher RGF for strong biogenic emission sources. While the site can be characterized as environment with a low nitrogen dioxide (NO2) concentration level ( 1 ppbv), the impact of biomass burning on the lower RGF during the dry season was confirmed by occasional enhancement of the NO2 level as an anthropogenic tracer. The results are further supported by additional error analyses for the cloud influence. Our findings are expected to be used to reduce model uncertainties related to VOC chemistry and secondary organic aerosol (SOA) formation

  16. Monitoring shipping emissions in the German Bight using MAX-DOAS measurements

    Science.gov (United States)

    Seyler, André; Wittrock, Folkard; Kattner, Lisa; Mathieu-Üffing, Barbara; Peters, Enno; Richter, Andreas; Schmolke, Stefan; Burrows, John P.

    2017-04-01

    Shipping is generally the most energy efficient transportation mode, but, at the same time, it accounts for four fifths of the worldwide total merchandise trade volume. As a result, shipping contributes a significant part to the emissions from the transportation sector. The majority of shipping emissions occurs within 400 km of land, impacting on air pollution in coastal areas and harbor towns. The North Sea has one of the highest ship densities in the world and the vast majority of ships heading for the port of Hamburg sail through the German Bight and into the river Elbe. A three-year time series of ground-based MAX-DOAS measurements of NO2 and SO2 on the island Neuwerk in the German Bight has been analyzed for contributions from shipping emissions. Measurements of individual ship plumes as well as of background pollution are possible from this location, which is 6-7 kilometers away from the main shipping lane towards the harbor of Hamburg. More than 2000 individual ship plumes have been identified in the data and analyzed for the emission ratio of SO2 to NO2, yielding an average ratio of 0.3 for the years 2013/2014. Contributions of ships and land-based sources to air pollution levels in the German Bight have been estimated, showing that despite the vicinity to the shipping lane, the contribution of shipping sources to air pollution is only about 40%. Since January 2015, much lower fuel sulfur content limits of 0.1% (before: 1.0%) apply in the North and Baltic Sea Emission Control Area (ECA). Comparing MAX-DOAS measurements from 2015/2016 (new regulation) to 2013/2014 (old regulation), a large reduction in SO2/NO2 ratios in shipping emissions and a significant reduction (by a factor of eight) in ambient coastal SO2 levels have been observed. In addition to that, selected shipping emission measurements from other measurement sites and campaigns are presented. This study is part of the project MeSMarT (Measurements of Shipping emissions in the Marine Troposphere

  17. Aliasing-free wideband beamforming using sparse signal representation

    NARCIS (Netherlands)

    Tang, Z.; Blacquière, G.; Leus, G.

    2011-01-01

    Sparse signal representation (SSR) is considered to be an appealing alternative to classical beamforming for direction-of-arrival (DOA) estimation. For wideband signals, the SSR-based approach constructs steering matrices, referred to as dictionaries in this paper, corresponding to different

  18. NO2 fluxes from Tijuana using a mobile mini-DOAS during Cal-Mex 2010

    Science.gov (United States)

    Rivera, Claudia; Barrera, Hugo; Grutter, Michel; Zavala, Miguel; Galle, Bo; Bei, Naifang; Li, Guohui; Molina, Luisa T.

    2013-05-01

    NO2 fluxes were measured using a mobile mini-DOAS during Cal-Mex 2010 field study, between May 15 and June 30, 2010, from the urban area of Tijuana, Baja California as well as the Rosarito power plant. The average calculated NO2 fluxes were 328 ± 184 (269 ± 201) g s-1, and 23.4 ± 4.9 (12.9 ± 11.9) g s-1 for Tijuana urban area and Rosarito power plant, respectively, using model based wind fields and onsite measurements (in parenthesis). Wind speed and wind direction data needed to estimate the fluxes were both modeled and obtained from radiosondes launched regularly during the field campaign, whereas the mixing layer height throughout the entire field campaign was measured using a ceilometer. Large variations in the NO2 fluxes from both the Tijuana urban area and Rosarito power plant were observed during Cal-Mex 2010; however, the variability was less when model based wind fields were used. Qualitative comparisons of modeled and measured plumes from the Tijuana urban area and Rosarito power plant showed good agreement.

  19. Crystal structure of a PFU-PUL domain pair of Saccharomyces cerevisiae Doa1/Ufd3.

    Science.gov (United States)

    Nishimasu, Rieko; Komori, Hirofumi; Higuchi, Yoshiki; Nishimasu, Hiroshi; Hiroaki, Hidekazu

    2010-10-21

    Doa1/Ufd3 is involved in ubiquitin (Ub)-dependent cellular processes in Saccharomyces cerevisiae, and consists of WD40, PFU, and PUL domains. Previous studies showed that the PFU and PUL domains interact with Ub and Hse1, and Cdc48, respectively. However, their detailed functional interactions with Doa1 remained elusive. We report the crystal structure of the PFU-PUL domain pair of yeast Doa1 at 1.9 Å resolution. The conserved surface of the PFU domain may be involved in binding to Ub and Hse1. Unexpectedly, the PUL domain consists of an Armadillo (ARM)-like repeat structure. The positively charged concave surface of the PUL domain may bind to the negatively charged C-terminal region of Cdc48. A structural comparison of Doa1 with Ufd2 revealed that they share a similar ARM-like repeat, supporting a model in which Doa1 and Ufd2 compete for Cdc48 binding and may dictate the fate of ubiquitinated proteins in the proteasome pathway.

  20. Determination of tropospheric vertical columns of NO2 and aerosol optical properties in a rural setting using MAX-DOAS

    Directory of Open Access Journals (Sweden)

    M. O. Wenig

    2011-12-01

    Full Text Available Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS measurements were performed in a rural location of southwestern Ontario during the Border Air Quality and Meteorology Study. Slant column densities (SCDs of NO2 and O4 were determined using the standard DOAS technique. Using a radiative transfer model and the O4 SCDs, aerosol optical depths were determined for clear sky conditions and compared to OMI, MODIS, AERONET, and local PM2.5 measurements. This aerosol information was input to a radiative transfer model to calculate NO2 air mass factors, which were fit to the measured NO2 SCDs to determine tropospheric vertical column densities (VCDs of NO2. The method of determining NO2 VCDs in this way was validated for the first time by comparison to composite VCDs derived from aircraft and ground-based measurements of NO2. The new VCDs were compared to VCDs of NO2 determined via retrievals from the satellite instruments SCIAMACHY and OMI, for overlapping time periods. The satellite-derived VCDs were higher, with a mean bias of +0.5–0.9×1015 molec cm−2. This last finding is different from previous studies whereby MAX-DOAS geometric VCDs were higher than satellite determinations, albeit for urban areas with higher VCDs. An effective boundary layer height, BLHeff, is defined as the ratio of the tropospheric VCD and the ground level concentration of NO2. Variations of BLHeff can be linked to time of day, source region, stability of the atmosphere, and the presence or absence of elevated NOx sources. In particular, a case study is shown where a high VCD and BLHeff were observed when an elevated industrial plume of NOx and SO2 was fumigated to the surface as a lake breeze impacted the measurement site. High BLHeff values (~1.9 km were observed during a regional smog event when high winds from the SW and high convection promoted mixing throughout the boundary layer. During this event, the regional line flux of NO2 through the region was

  1. Car MAX-DOAS measurements around entire cities: quantification of NOx emissions from the cities of Mannheim and Ludwigshafen (Germany

    Directory of Open Access Journals (Sweden)

    U. Platt

    2010-06-01

    Full Text Available We present car Multi-Axis (MAX- DOAS observations of tropospheric NO2 carried out on circles around the cities of Mannheim and Ludwigshafen (Germany on 24 August 2006. Together with information on wind speed and direction, the total emissions of the encircled source(s are quantified from these measurements. In contrast to recent similar studies based on zenith scattered sun light (elevation angle of 90°, we use a MAX-DOAS instrument mounted on a car, which observes scattered sun light under different elevation angles (here 45°, and 90°. Compared to simple zenith sky observations, MAX-DOAS observations have higher sensitivity and reduced uncertainty, and avoid systematic offsets in the determination of the vertically integrated trace gas concentration. The determination of the absolute value of the integrated tropospheric trace gas concentrations is especially important for the calculation of absolute trace gas fluxes through arbitrary transects. However, even if emission sources are completely surrounded, systematic offsets in the measured vertically integrated trace gas concentration can lead to errors in the determined total emissions, especially for observations around extended areas. In this study we discuss and quantify different error sources. In most cases, the largest error source is the variability and imperfect knowledge of the wind field. In addition – depending on the trace species observed - also chemical transformations between the emission sources and the measurement location have to be considered. For that purpose we use local observations within the encircled area to quantify and/or correct these errors. From our observations we derive a total NOx emission from the Mannheim/Ludwigshafen area of (7.4±1.8×1024 molec/sec, which if assumed to be constant throughout the year would correspond to a total emission of 17 830±4340 t/yr (calculated with the mass of NO2 t/yr, consistent with existing emission estimates. From our

  2. Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere

    Science.gov (United States)

    Volten, H.; Bergwerff, J. B.; Haaima, M.; Lolkema, D. E.; Berkhout, A. J. C.; van der Hoff, G. R.; Potma, C. J. M.; Wichink Kruit, R. J.; van Pul, W. A. J.; Swart, D. P. J.

    2012-02-01

    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM: the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference-free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 μg m-3, have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 μg m-3 for ammonia for 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day, the (mini)DOAS and AMOR results agree reasonably well, although an offset of the AMOR values compared to the (mini)DOAS results exists. On short time scales, the (mini)DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini)DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.

  3. Retrieval columns of SO2 in industrial chimneys using DOAS passive in traverse

    Science.gov (United States)

    Galicia Mejía, Rubén; de la Rosa Vázquez, José Manuel; Sosa Iglesias, Gustavo

    2011-10-01

    The optical Differential Optical Absorption Spectroscopy (DOAS) is a technique to measure pollutant emissions like SO2, from point sources and total fluxes in the atmosphere. Passive DOAS systems use sunlight like source. Measurements with such systems can be made in situ and in real time. The goal of this work is to report the implementation of hardware and software of a portable system to evaluate the pollutants emitted in the atmosphere by industrial chimneys. We show SO2 measurements obtained around PEMEX refinerys in Tula Hidalgo that enables the identification of their pollution degree with the knowledge of speed wind.

  4. Investigations of temporal and spatial distribution of precursors SO2 and NO2 vertical columns in the North China Plain using mobile DOAS

    Science.gov (United States)

    Wu, Fengcheng; Xie, Pinhua; Li, Ang; Mou, Fusheng; Chen, Hao; Zhu, Yi; Zhu, Tong; Liu, Jianguo; Liu, Wenqing

    2018-02-01

    Recently, Chinese cities have suffered severe events of haze air pollution, particularly in the North China Plain (NCP). Investigating the temporal and spatial distribution of pollutants, emissions, and pollution transport is necessary to better understand the effect of various sources on air quality. We report on mobile differential optical absorption spectroscopy (mobile DOAS) observations of precursors SO2 and NO2 vertical columns in the NCP in the summer of 2013 (from 11 June to 7 July) in this study. The different temporal and spatial distributions of SO2 and NO2 vertical column density (VCD) over this area are characterized under various wind fields. The results show that transport from the southern NCP strongly affects air quality in Beijing, and the transport route, particularly SO2 transport on the route of Shijiazhuang-Baoding-Beijing, is identified. In addition, the major contributors to SO2 along the route of Shijiazhuang-Baoding-Beijing are elevated sources compared to low area sources for the route of Dezhou-Cangzhou-Tianjin-Beijing; this is found using the interrelated analysis between in situ and mobile DOAS observations during the measurement periods. Furthermore, the discussions on hot spots near the city of JiNan show that average observed width of polluted air mass is 11.83 and 17.23 km associated with air mass diffusion, which is approximately 60 km away from emission sources based on geometrical estimation. Finally, a reasonable agreement exists between the Ozone Monitoring Instrument (OMI) and mobile DOAS observations, with a correlation coefficient (R2) of 0.65 for NO2 VCDs. Both datasets also have a similar spatial pattern. The fitted slope of 0.55 is significantly less than unity, which can reflect the contamination of local sources, and OMI observations are needed to improve the sensitivities to the near-surface emission sources through improvements of the retrieval algorithm or the resolution of satellites.

  5. Retrieval of free-tropospheric BrO from MAX-DOAS measurements at the high-altitude alpine station of Jungfraujoch

    Science.gov (United States)

    Van Roozendael, Michel; Hendrick, Francois; De Smedt, Isabelle; Fayt, Caroline; Gielen, Clio; Hermans, Christian; Pinardi, Gaia; Tack, Frederik; Theys, Nicolas

    2014-05-01

    There are currently many open questions about the sources, transport, and photochemical processing that control the abundance of BrO and its precursors in the global troposphere. Recent experimental studies based on various platforms and instrumentations indicate contrasting results reflecting the scarcity of the measurements and the experimental challenge of quantifying the typically low abundance levels of BrO. Modeling studies indicate however that the presence of only 1-2 pptv levels of reactive bromine has important consequences for free tropospheric ozone with indirect climate implications. The MAX-DOAS technique offers high sensitivity for near-surface trace gas measurements and it is well suited to BrO detection. From a high altitude site such as the Jungfraujoch which is located in the Swiss Alps at about 3600 m ASL, the free-troposphere can be sampled under favourable conditions. We report on attempts to quantify the free tropospheric BrO level based on MAXDOAS measurements performed by BIRA-IASB in the period from June 2010 until December 2012. Retrievals are based on the DOAS method followed by vertical profile inversion using an Optimal Estimation scheme. The possible sources of bias that can affect the spectral retrieval of BrO are carefully investigated and various sensitivity tests are performed to assess the stability of the inversion. Results are compared with independent estimates of the mid-latitude tropospheric BrO based on satellite measurements.

  6. Eight-component retrievals from ground-based MAX-DOAS observations

    Directory of Open Access Journals (Sweden)

    H. Irie

    2011-06-01

    Full Text Available We attempt for the first time to retrieve lower-tropospheric vertical profile information for 8 quantities from ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS observations. The components retrieved are the aerosol extinction coefficients at two wavelengths, 357 and 476 nm, and NO2, HCHO, CHOCHO, H2O, SO2, and O3 volume mixing ratios. A Japanese MAX-DOAS profile retrieval algorithm, version 1 (JM1, is applied to observations performed at Cabauw, the Netherlands (51.97° N, 4.93° E, in June–July 2009 during the Cabauw Intercomparison campaign of Nitrogen Dioxide measuring Instruments (CINDI. Of the retrieved profiles, we focus here on the lowest-layer data (mean values at altitudes 0–1 km, where the sensitivity is usually highest owing to the longest light path. In support of the capability of the multi-component retrievals, we find reasonable overall agreement with independent data sets, including a regional chemical transport model (CHIMERE and in situ observations performed near the surface (2–3 m and at the 200-m height level of the tall tower in Cabauw. Plumes of enhanced HCHO and SO2 were likely affected by biogenic and ship emissions, respectively, and an improvement in their emission strengths is suggested for better agreement between CHIMERE simulations and MAX-DOAS observations. Analysis of air mass factors indicates that the horizontal spatial representativeness of MAX-DOAS observations is about 3–15 km (depending mainly on aerosol extinction, comparable to or better than the spatial resolution of current UV-visible satellite observations and model calculations. These demonstrate that MAX-DOAS provides multi-component data useful for the evaluation of satellite observations and model calculations and can play an important role in bridging different data sets having different spatial resolutions.

  7. The effect of cloud screening on MAX-DOAS aerosol retrievals.

    Science.gov (United States)

    Gielen, Clio; Van Roozendael, Michel; Hendrik, Francois; Fayt, Caroline; Hermans, Christian; Pinardi, Gaia; De Backer, Hugo; De Bock, Veerle; Laffineur, Quentin; Vlemmix, Tim

    2014-05-01

    In recent years, ground-based multi-axis differential absorption spectroscopy (MAX-DOAS) has shown to be ideally suited for the retrieval of tropospheric trace gases and deriving information on the aerosol properties. These measurements are invaluable to our understanding of the physics and chemistry of the atmospheric system, and the impact on the Earth's climate. Unfortunately, MAX-DOAS measurements are often performed under strong non-clear-sky conditions, causing strong data quality degradation and uncertainties on the retrievals. Here we present the result of our cloud-screening method, using the colour index (CI), on aerosol retrievals from MAX-DOAS measurements (AOD and vertical profiles). We focus on two large data sets, from the Brussels and Beijing area. Using the CI we define 3 different sky conditions: bad (=full thick cloud cover/extreme aerosols), mediocre (=thin clouds/aerosols) and good (=clear sky). We also flag the presence of broken/scattered clouds. We further compare our cloud-screening method with results from cloud-cover fractions derived from thermic infrared measurements. In general, our method shows good results to qualify the sky and cloud conditions of MAX-DOAS measurements, without the need for other external cloud-detection systems. Removing data under bad-sky and broken-cloud conditions results in a strongly improved agreement, in both correlation and slope, between the MAX-DOAS aerosol retrievals and data from other instruments (e.g. AERONET, Brewer). With the improved AOD retrievals, the seasonal and diurnal variations of the aerosol content and vertical distribution at both sites can be investigated in further detail. By combining with additional information derived by other instruments (Brewer, lidar, ...) operated at the stations, we will further study the observed aerosol characteristics, and their influence on and by meteorological conditions such as clouds and/or the boundary layer height.

  8. Differential optical absorption spectroscopy (DOAS and air mass factor concept for a multiply scattering vertically inhomogeneous medium: theoretical consideration

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    V. V. Rozanov

    2010-06-01

    Full Text Available The Differential Optical Absorption Spectroscopy (DOAS technique is widely used to retrieve amounts of atmospheric species from measurements of the direct solar light transmitted through the Earth's atmosphere as well as of the solar light scattered in the atmosphere or reflected from the Earth's surface. For the transmitted direct solar light the theoretical basis of the DOAS technique represented by the Beer-Lambert law is well studied. In contrast, scarcely investigated is the theoretical basis and validity range of the DOAS method for those cases where the contribution of the multiple scattering processes is not negligible. Our study is intended to fill this gap by means of a theoretical investigation of the applicability of the DOAS technique for the retrieval of amounts of atmospheric species from observations of the scattered solar light with a non-negligible contribution of the multiple scattering.

    Starting from the expansion of the intensity logarithm in the functional Taylor series we formulate the general form of the DOAS equation. The thereby introduced variational derivative of the intensity logarithm with respect to the variation of the gaseous absorption coefficient, which is often referred to as the weighting function, is demonstrated to be closely related to the air mass factor. Employing some approximations we show that the general DOAS equation can be rewritten in the form of the weighting function (WFDOAS, the modified (MDOAS, and the standard DOAS equations. For each of these forms a specific equation for the air mass factor follows which, in general, is not suitable for other forms of the DOAS equation. Furthermore, the validity range of the standard DOAS equation is quantitatively investigated using a suggested criterion of a weak absorption.

    The results presented in this study are intended to provide a basis for a better understanding of the applicability range of different forms of the DOAS equation as

  9. Development of a cloud-screening method for MAX-DOAS measurements

    Science.gov (United States)

    Gielen, Clio; Van Roozendael, Michel; Hendrik, Francois; Fayt, Caroline; Hermans, Christian; Pinardi, Gaia; Vlemmix, Tim

    2013-04-01

    In recent years, ground-based multi-axis differential absorption spectroscopy (MAX-DOAS) has shown to be ideally suited for the retrieval of tropospheric trace gases and deriving information on the aerosol properties. These measurements are invaluable to our understanding of the physics and chemistry of the atmospheric system, and the impact on the Earth's climate. Unfortunately, MAX-DOAS measurements are often performed under (partially) cloudy conditions, causing data quality degradation and higher uncertainties on the retrievals. A high aerosol load and/or a strong cloud cover can introduce additional photon absorption or multiple scattering. The first effect strongly impacts the retrieved differential slant columns (DSCDs) of the trace gases, leading to an underestimation of the atmospheric column density. Multiple scattering, on the other hand, becomes important for low clouds with a high optical depth, and cause a strong increase in the retrieved trace gas DSCDs. The presence of thin clouds can furthermore introduce a degeneracy in the retrieved aerosol optical depth, since they will have similar effect on the MAX-DOAS measurements. In this case, only information on the trace gas DSCDs can be successfully retrieved. If the cloud cover consists of broken or scattered clouds, the MAX-DOAS method becomes very unstable, since the different elevation angels will probe regions of the sky with strongly deviating properties. Here we present a method to qualify the sky and cloud conditions, using the colour index and O4 DSCDs, as derived from the MAX-DOAS measurements. The colour index is defined as the ratio of the intensities at the short- and long-wavelength part of the visible spectral range, typically at 400 nm and 670 nm. For increasing optical thickness due to clouds or aerosols, the colour index values decrease and values for different elevation angles converge. In the case of broken clouds, the colour index shows a strong and rapid temporal variation, which

  10. SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors

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    R. Sussmann

    2012-10-01

    Full Text Available Global observations of column-averaged dry air mole fractions of carbon dioxide (CO2, denoted by XCO2 , retrieved from SCIAMACHY on-board ENVISAT can provide important and missing global information on the distribution and magnitude of regional CO2 surface fluxes. This application has challenging precision and accuracy requirements. In a previous publication (Heymann et al., 2012, it has been shown by analysing seven years of SCIAMACHY WFM-DOAS XCO2 (WFMDv2.1 that unaccounted thin cirrus clouds can result in significant errors. In order to enhance the quality of the SCIAMACHY XCO2 data product, we have developed a new version of the retrieval algorithm (WFMDv2.2, which is described in this manuscript. It is based on an improved cloud filtering and correction method using the 1.4 μm strong water vapour absorption and 0.76 μm O2-A bands. The new algorithm has been used to generate a SCIAMACHY XCO2 data set covering the years 2003–2009. The new XCO2 data set has been validated using ground-based observations from the Total Carbon Column Observing Network (TCCON. The validation shows a significant improvement of the new product (v2.2 in comparison to the previous product (v2.1. For example, the standard deviation of the difference to TCCON at Darwin, Australia, has been reduced from 4 ppm to 2 ppm. The monthly regional-scale scatter of the data (defined as the mean intra-monthly standard deviation of all quality filtered XCO2 retrievals within a radius of 350 km around various locations has also been reduced, typically by a factor of about 1.5. Overall, the validation of the new WFMDv2.2 XCO2 data product can be summarised by a single measurement precision of 3.8 ppm, an estimated regional-scale (radius of 500 km precision of monthly averages of 1.6 ppm and an estimated regional-scale relative accuracy of 0.8 ppm. In addition to the comparison with the limited number of TCCON sites, we also present a comparison with NOAA's global CO2 modelling

  11. On Improvements of Cyclic MUSIC

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    H. Howard Fan

    2005-01-01

    Full Text Available Many man-made signals encountered in communications exhibit cyclostationarity. By exploiting cyclostationarity, cyclic MUSIC has been shown to be able to separate signals with different cycle frequencies, thus, to be able to perform signal selective direction of-arrival (DOA estimation. However, as will be shown in this paper, the DOA estimation of cyclic MUSIC is actually biased. We show in this paper that by properly choosing the frequency for evaluating the steering vector, the bias of DOA estimation can be substantially reduced and the performance can be improved. Furthermore, we propose another algorithm exploiting cyclic conjugate correlation to further improve the performance of DOA estimation. Simulation results show the effectiveness of both of our methods.

  12. Retrieval of tropospheric HCHO in El Salvador using ground based DOAS

    Science.gov (United States)

    Abarca, W.; Gamez, K.; Rudamas, C.

    2017-12-01

    Formaldehyde (HCHO) is the most abundant carbonyl in the atmosphere, being an intermediate product in the oxidation of most volatile organic compounds (VOCs). HCHO is carcinogenic, and highly water soluble [1]. HCHO can originate from biomass burning and fossil fuel combustion and has been observed from satellite and ground-based sensors by using the Differential Optical Absorption Spectroscopy (DOAS) technique [2].DOAS products can be used for air quality monitoring, validation of chemical transport models, validation of satellite tropospheric column density retrievals, among others [3]. In this study, we report on column density levels of HCHO measured by ground based Multi-Axis -DOAS in different locations of El Salvador in March, 2015. We have not observed large differences of the HCHO column density values at different viewing directions. This result points out a reasonably polluted and hazy atmosphere in the measuring sites, as reported by other authors [4]. Average values ranging from 1016 to 1017 molecules / cm2 has been obtained. The contribution of vehicular traffic and biomass burning to the column density levels in these sites of El Salvador will be discussed. [1] A. R. Garcia et al., Atmos. Chem. Phys. 6, 4545 (2006) [2] E. Peters et al., Atmos. Chem. Phys. 12, 11179 (2012) [3] T. Vlemmix, et al. Atmos. Meas. Tech., 8, 941-963, 2015 [4] A. Heckel et al., Atmos. Chem. Phys. 5, (2005)

  13. Observation of the volcanic plume of Eyjafjallajoekull over continental Europe by MAX-DOAS

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, S.; Bobrowski, N.; Friess, U.; Platt, U. [IUP, University of Heidelberg (Germany); Flentje, H. [DWD, Hohenpeissenberg (Germany); Hoermann, C.; Sihler, H. [IUP, University of Heidelberg (Germany); MPI, Mainz (Germany); Kern, C. [USGS, Vancouver (Canada); Wagner, T. [MPI, Mainz (Germany)

    2011-07-01

    The recent eruption of Eyjafjallajoekull Volcano (Iceland) and the emitted ash plume which disrupted commercial air traffic over Europe has led to an exhaustive debate on how to improve our ability to quantitatively determine the ash load in the atmosphere as a function of time and geographical location. Satellite instruments detecting ash and SO{sub 2} and ground-based LIDAR stations can help constrain atmospheric transport and meteorology models used to predict ash dispersion. However, MAX-DOAS represents an additional tool with considerable potential for the quantitative detection of elevated volcanic ash and SO{sub 2} plumes. It performs especially well during weather conditions in which satellites and LIDARs are impeded in their effectiveness, e.g. in the case of dense clouds above or below the plume, respectively. Here, the advantages and disadvantages of the DOAS technique are discussed, and its potential for monitoring of volcanic ash hazards explored. Results of ash and SO{sub 2} measurements of the Eyjafjallajoekull plume as it passed over Heidelberg are presented as an example of a positive detection of a highly diluted volcanic plume. Their low cost and complementary nature makes MAX-DOAS a promising technology in the field of aviation hazard detection and management.

  14. Ship-based MAX-DOAS measurements of tropospheric NO2, SO2, and HCHO distribution along the Yangtze River

    Science.gov (United States)

    Hong, Qianqian; Liu, Cheng; Chan, Ka Lok; Hu, Qihou; Xie, Zhouqing; Liu, Haoran; Si, Fuqi; Liu, Jianguo

    2018-04-01

    In this paper, we present ship-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of tropospheric trace gases' distribution along the Yangtze River during winter 2015. The measurements were performed along the Yangtze River between Shanghai and Wuhan, covering major industrial areas in eastern China. Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved using the air mass factor calculated by the radiative transfer model. Enhanced tropospheric NO2 and SO2 VCDs were detected over downwind areas of industrial zones over the Yangtze River. In addition, spatial distributions of atmospheric pollutants are strongly affected by meteorological conditions; i.e., positive correlations were found between concentration of pollutants and wind speed over these areas, indicating strong influence of transportation of pollutants from high-emission upwind areas along the Yangtze River. Comparison of tropospheric NO2 VCDs between ship-based MAX-DOAS and Ozone Monitoring Instrument (OMI) satellite observations shows good agreement with each other, with a Pearson correlation coefficient (R) of 0.82. In this study, the NO2 / SO2 ratio was used to estimate the relative contributions of industrial sources and vehicle emissions to ambient NO2 levels. Analysis results of the NO2 / SO2 ratio show a higher contribution of industrial NO2 emissions in Jiangsu Province, while NO2 levels in Jiangxi and Hubei provinces are mainly related to vehicle emissions. These results indicate that different pollution control strategies should be applied in different provinces. In addition, multiple linear regression analysis of ambient carbon monoxide (CO) and odd oxygen (Ox) indicated that the primary emission and secondary formation of HCHO contribute 54.4 ± 3.7 % and 39.3 ± 4.3 % to the ambient HCHO, respectively. The largest contribution from primary emissions in winter suggested that

  15. Improvement to the PhytoDOAS method for identification of coccolithophores using hyper-spectral satellite data

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    A. Sadeghi

    2012-11-01

    Full Text Available The goal of this study was to improve PhytoDOAS, which is a new retrieval method for quantitative identification of major phytoplankton functional types (PFTs using hyper-spectral satellite data. PhytoDOAS is an extension of the Differential Optical Absorption Spectroscopy (DOAS, a method for detection of atmospheric trace gases, developed for remote identification of oceanic phytoplankton groups. Thus far, PhytoDOAS has been successfully exploited to identify cyanobacteria and diatoms over the global ocean from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY hyper-spectral data. This study aimed to improve PhytoDOAS for remote identification of coccolithophores, another functional group of phytoplankton. The main challenge for retrieving more PFTs by PhytoDOAS is to overcome the correlation effects between different PFT absorption spectra. Different PFTs are composed of different types and amounts of pigments, but also have pigments in common, e.g. chl a, causing correlation effects in the usual performance of the PhytoDOAS retrieval. Two ideas have been implemented to improve PhytoDOAS for the PFT retrieval of more phytoplankton groups. Firstly, using the fourth-derivative spectroscopy, the peak positions of the main pigment components in each absorption spectrum have been derived. After comparing the corresponding results of major PFTs, the optimized fit-window for the PhytoDOAS retrieval of each PFT was determined. Secondly, based on the results from derivative spectroscopy, a simultaneous fit of PhytoDOAS has been proposed and tested for a selected set of PFTs (coccolithophores, diatoms and dinoflagellates within an optimized fit-window, proven by spectral orthogonality tests. The method was then applied to the processing of SCIAMACHY data over the year 2005. Comparisons of the PhytoDOAS coccolithophore retrievals in 2005 with other coccolithophore-related data showed similar patterns in their

  16. Iterative maximum a posteriori (IMAP-DOAS for retrieval of strongly absorbing trace gases: Model studies for CH4 and CO2 retrieval from near infrared spectra of SCIAMACHY onboard ENVISAT

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    C. Frankenberg

    2005-01-01

    Full Text Available In the past, differential optical absorption spectroscopy (DOAS has mostly been employed for atmospheric trace gas retrieval in the UV/Vis spectral region. New spectrometers such as SCIAMACHY onboard ENVISAT also provide near infrared channels and thus allow for the detection of greenhouse gases like CH4, CO2, or N2O. However, modifications of the classical DOAS algorithm are necessary to account for the idiosyncrasies of this spectral region, i.e. the temperature and pressure dependence of the high resolution absorption lines. Furthermore, understanding the sensitivity of the measurement of these high resolution, strong absorption lines by means of a non-ideal device, i.e. having finite spectral resolution, is of special importance. This applies not only in the NIR, but can also prove to be an issue for the UV/Vis spectral region. This paper presents a modified iterative maximum a posteriori-DOAS (IMAP-DOAS algorithm based on optimal estimation theory introduced to the remote sensing community by rodgers76. This method directly iterates the vertical column densities of the absorbers of interest until the modeled total optical density fits the measurement. Although the discussion in this paper lays emphasis on satellite retrieval, the basic principles of the algorithm also hold for arbitrary measurement geometries. This new approach is applied to modeled spectra based on a comprehensive set of atmospheric temperature and pressure profiles. This analysis reveals that the sensitivity of measurement strongly depends on the prevailing pressure-height. The IMAP-DOAS algorithm properly accounts for the sensitivity of measurement on pressure due to pressure broadening of the absorption lines. Thus, biases in the retrieved vertical columns that would arise in classical algorithms, are obviated. Here, we analyse and quantify these systematic biases as well as errors due to variations in the temperature and pressure profiles, which is indispensable for

  17. Parameterizing radiative transfer to convert MAX-DOAS dSCDs into near-surface box-averaged mixing ratios

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    R. Sinreich

    2013-06-01

    Full Text Available We present a novel parameterization method to convert multi-axis differential optical absorption spectroscopy (MAX-DOAS differential slant column densities (dSCDs into near-surface box-averaged volume mixing ratios. The approach is applicable inside the planetary boundary layer under conditions with significant aerosol load, and builds on the increased sensitivity of MAX-DOAS near the instrument altitude. It parameterizes radiative transfer model calculations and significantly reduces the computational effort, while retrieving ~ 1 degree of freedom. The biggest benefit of this method is that the retrieval of an aerosol profile, which usually is necessary for deriving a trace gas concentration from MAX-DOAS dSCDs, is not needed. The method is applied to NO2 MAX-DOAS dSCDs recorded during the Mexico City Metropolitan Area 2006 (MCMA-2006 measurement campaign. The retrieved volume mixing ratios of two elevation angles (1° and 3° are compared to volume mixing ratios measured by two long-path (LP-DOAS instruments located at the same site. Measurements are found to agree well during times when vertical mixing is expected to be strong. However, inhomogeneities in the air mass above Mexico City can be detected by exploiting the different horizontal and vertical dimensions probed by the MAX-DOAS and LP-DOAS instruments. In particular, a vertical gradient in NO2 close to the ground can be observed in the afternoon, and is attributed to reduced mixing coupled with near-surface emission inside street canyons. The existence of a vertical gradient in the lower 250 m during parts of the day shows the general challenge of sampling the boundary layer in a representative way, and emphasizes the need of vertically resolved measurements.

  18. SO2 EMISSION MEASUREMENT BY DOAS (DIFFERENTIAL OPTICAL ABSORPTION SPECTROSCOPY AND COSPEC (CORRELATION SPECTROSCOPY AT MERAPI VOLCANO (INDONESIA

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    Hanik Humaida

    2010-06-01

    Full Text Available The SO2 is one of the volcanic gases that can use as indicator of volcano activity. Commonly, SO2 emission is measured by COSPEC (Correlation Spectroscopy. This equipment has several disadvantages; such as heavy, big in size, difficulty in finding spare part, and expensive. DOAS (Differential Optical Absorption Spectroscopy is a new method for SO2 emission measurement that has advantages compares to the COSPEC. Recently, this method has been developed. The SO2 gas emission measurement of Gunung Merapi by DOAS has been carried out at Kaliadem, and also by COSPEC method as comparation. The differences of the measurement result of both methods are not significant. However, the differences of minimum and maximum result of DOAS method are smaller than that of the COSPEC. It has range between 51 ton/day and 87 ton/day for DOAS and 87 ton/day and 201 ton/day for COSPEC. The measurement of SO2 gas emission evaluated with the seismicity data especially the rockfall showed the presence of the positive correlation. It may cause the gas pressure in the subsurface influencing instability of 2006 eruption lava.   Keywords: SO2 gas, Merapi, DOAS, COSPEC

  19. Near-field/far-field azimuth and elevation angle estimation using a single vector hydrophone

    Czech Academy of Sciences Publication Activity Database

    Tichavský, Petr; Wong, K. T.; Zoltowski, M.

    2001-01-01

    Roč. 49, č. 11 (2001), s. 2498-2510 ISSN 1053-587X R&D Projects: GA ČR GA102/97/0466; GA ČR GA102/01/0021 Institutional research plan: AV0Z1075907 Keywords : acoustic signal processing * array signal processing * direction-of-arrival estimation Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.268, year: 2001

  20. Enhanced tropospheric BrO over Antarctic sea ice in mid winter observed by MAX-DOAS on board the research vessel Polarstern

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    T. Wagner

    2007-06-01

    Full Text Available We present Multi AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS observations of tropospheric BrO carried out on board the German research vessel Polarstern during the Antarctic winter 2006. Polarstern entered the area of first year sea ice around Antarctica on 24 June 2006 and stayed within this area until 15 August 2006. For the period when the ship cruised inside the first year sea ice belt, enhanced BrO concentrations were almost continuously observed. Outside the first year sea ice belt, typically low BrO concentrations were found. Based on back trajectory calculations we find a positive correlation between the observed BrO differential slant column densities (ΔSCDs and the duration for which the air masses had been in contact with the sea ice surface prior to the measurement. While we can not completely rule out that in several cases the highest BrO concentrations might be located close to the ground, our observations indicate that the maximum BrO concentrations might typically exist in a (possibly extended layer around the upper edge of the boundary layer. Besides the effect of a decreasing pH of sea salt aerosol with altitude and therefore an increase of BrO with height, this finding might be also related to vertical mixing of air from the free troposphere with the boundary layer, probably caused by convection over the warm ocean surface at polynyas and cracks in the ice. Strong vertical gradients of BrO and O3 could also explain why we found enhanced BrO levels almost continuously for the observations within the sea ice. Based on our estimated BrO profiles we derive BrO mixing ratios of several ten ppt, which is slightly higher than many existing observations. Our observations indicate that enhanced BrO concentrations around Antarctica exist about one month earlier than observed by satellite instruments. From detailed radiative transfer simulations we find that MAX-DOAS observations are up to about one order of

  1. MAX-DOAS measurements of HONO slant column densities during the MAD-CAT campaign: inter-comparison, sensitivity studies on spectral analysis settings, and error budget

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    Y. Wang

    2017-10-01

    about half of the systematic difference between the real measurements.The differences of HONO delta SCDs retrieved in the selected three spectral ranges 335–361, 335–373 and 335–390 nm are considerable (up to 0.57  ×  1015 molecules cm−2 for both real measurements and synthetic spectra. We performed sensitivity studies to quantify the dominant systematic error sources and to find a recommended DOAS setting in the three spectral ranges. The results show that water vapour absorption, temperature and wavelength dependence of O4 absorption, temperature dependence of Ring spectrum, and polynomial and intensity offset correction all together dominate the systematic errors. We recommend a fit range of 335–373 nm for HONO retrievals. In such fit range the overall systematic uncertainty is about 0.87  ×  1015 molecules cm−2, much smaller than those in the other two ranges. The typical random uncertainty is estimated to be about 0.16  ×  1015 molecules cm−2, which is only 25 % of the total systematic uncertainty for most of the instruments in the MAD-CAT campaign. In summary for most of the MAX-DOAS instruments for elevation angle below 5°, half daytime measurements (usually in the morning of HONO delta SCD can be over the detection limit of 0.2  ×  1015 molecules cm−2 with an uncertainty of  ∼  0.9  ×  1015 molecules cm−2.

  2. The impact of vibrational Raman scattering of air on DOAS measurements of atmospheric trace gases

    Science.gov (United States)

    Lampel, J.; Frieß, U.; Platt, U.

    2015-09-01

    In remote sensing applications, such as differential optical absorption spectroscopy (DOAS), atmospheric scattering processes need to be considered. After inelastic scattering on N2 and O2 molecules, the scattered photons occur as additional intensity at a different wavelength, effectively leading to "filling-in" of both solar Fraunhofer lines and absorptions of atmospheric constituents, if the inelastic scattering happens after the absorption. Measured spectra in passive DOAS applications are typically corrected for rotational Raman scattering (RRS), also called Ring effect, which represents the main contribution to inelastic scattering. Inelastic scattering can also occur in liquid water, and its influence on DOAS measurements has been observed over clear ocean water. In contrast to that, vibrational Raman scattering (VRS) of N2 and O2 has often been thought to be negligible, but it also contributes. Consequences of VRS are red-shifted Fraunhofer structures in scattered light spectra and filling-in of Fraunhofer lines, additional to RRS. At 393 nm, the spectral shift is 25 and 40 nm for VRS of O2 and N2, respectively. We describe how to calculate VRS correction spectra according to the Ring spectrum. We use the VRS correction spectra in the spectral range of 420-440 nm to determine the relative magnitude of the cross-sections of VRS of O2 and N2 and RRS of air. The effect of VRS is shown for the first time in spectral evaluations of Multi-Axis DOAS data from the SOPRAN M91 campaign and the MAD-CAT MAX-DOAS intercomparison campaign. The measurements yield in agreement with calculated scattering cross-sections that the observed VRS(N2) cross-section at 393 nm amounts to 2.3 ± 0.4 % of the cross-section of RRS at 433 nm under tropospheric conditions. The contribution of VRS(O2) is also found to be in agreement with calculated scattering cross-sections. It is concluded, that this phenomenon has to be included in the spectral evaluation of weak absorbers as it

  3. CARIBIC DOAS observations of nitrous acid and formaldehyde in a large convective cloud

    Science.gov (United States)

    Heue, K.-P.; Riede, H.; Walter, D.; Brenninkmeijer, C. A. M.; Wagner, T.; Frieß, U.; Platt, U.; Zahn, A.; Stratmann, G.; Ziereis, H.

    2014-07-01

    The chemistry in large thunderstorm clouds is influenced by local lightning-NOx production and uplift of boundary layer air. Under these circumstances trace gases like nitrous acid (HONO) or formaldehyde (HCHO) are expected to be formed or to reach the tropopause region. However, up to now only few observations of HONO at this altitude have been reported. Here we report on a case study where enhancements in HONO, HCHO and nitrogen oxides (NOx) were observed by the CARIBIC flying laboratory (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container). The event took place in a convective system over the Caribbean Sea in August 2011. Inside the cloud the light path reaches up to 100 km. Therefore the DOAS instrument on CARIBIC was very sensitive to the tracers inside the cloud. Based on the enhanced slant column densities of HONO, HCHO and NO2, average mixing ratios of 37, 468 and 210 ppt, respectively, were calculated. These data represent averages for constant mixing ratios inside the cloud. However, a large dependency on the assumed profile is found; for HONO a mixing ratio of 160 ppt is retrieved if the total amount is assumed to be situated in the uppermost 2 km of the cloud. The NO in situ instrument measured peaks up to 5 ppb NO inside the cloud; the background in the cloud was about 1.3 ppb, and hence clearly above the average outside the cloud (≈ 150 ppt). The high variability and the fact that the enhancements were observed over a pristine marine area led to the conclusion that, in all likelihood, the high NO concentrations were caused by lighting. This assumption is supported by the number of flashes that the World Wide Lightning Location Network (WWLLN) counted in this area before and during the overpass. The chemical box model CAABA is used to estimate the NO and HCHO source strengths which are necessary to explain our measurements. For NO a source strength of 10 × 109 molec cm-2 s-1 km-1 is found, which

  4. The effect of management of transport and lairage conditions on broiler chicken breast meat quality and DOA (Death on Arrival

    Directory of Open Access Journals (Sweden)

    Alexandre Oba

    2009-11-01

    Full Text Available The aim of this work was to evaluate the influence of time of broiler chicken transportation and lairage prior to slaughtering on the occurrence of PSE (Pale, Soft, Exudative meat and Death On Arrival (DOA under non-commercial conditions in the Brazilian summer. Male birds (n=250 from a commercial line were subjected to different periods of journey (30, 90, and 180 min and lairage (0, 90, and 180 min before slaughtering. The occurrence of PSE was higher in broilers subjected to shorter journeys and lairage periods, whereas DOA was more pronounced upon longer periods of transport and lairage. The DOA occurrence percentage was much higher in comparison to commercially available figures, confirming that broiler chickens are very sensitive to both transport and lairage maneuvers.O objetivo desse trabalho foi avaliar a influência do tempo de transporte e período de descanso antes do abate dos frangos na ocorrência das carnes PSE (Pale, Soft, Exudative: Pálido, Amolecido e Exsudativo e DOA (Dead On Arrival: Morte Na Chegada nas condições não comerciais durante o verão brasileiro. Frangos machos (n=250 de uma linhagem comercial foram submetidos a diferentes periodos de jornada (30, 90 e 180 min e descanso (0, 90 e 180 min antes do abate. A ocorrência do PSE foi maior em frangos submetidos tanto em tempos para as viagens curtas como para o de descanso enquanto que DOA foi mais pronunciada em condições de jornadas longas e maior periodo de descanso. A porcentagem da ocorrência do DOA foi maior ao se comparar com os resultados obtidas por empresas comerciais confirmando que os frangos são sensiveis às condições das viagens e de descanso a que são submetidos.

  5. Hemispherical Scanning Imaging DOAS: Resolving nitrogen dioxide in the urban environment

    Science.gov (United States)

    Leigh, R. J.; Graves, R. R.; Lawrence, J.; Faloon, K.; Monks, P. S.

    2012-12-01

    Imaging DOAS techniques have been used for nitrogen dioxide and sulfer dioxide for a number of years. This presentation describes a novel system which images concentrations of nitrogen dioxide by scanning an imaging spectrometer 360 degrees azimuthally, covering a region from 5 degrees below the horizon, to the zenith. The instrument has been built at the University of Leicester (UK), on optical designs by Surrey Satellite Technologies Ltd, and incorporates an Offner relay with Schwarzchild fore-optics, in a rotating mount. The spectrometer offers high fidelity spectroscopic retrievals of nitrogen dioxide as a result of a reliable Gaussian line shape, zero smile and low chromatic aberration. The full hemispherical scanning provides complete coverage of nitrogen dioxide concentrations above approximately 5 ppbv in urban environments. Through the use of multiple instruments, the three-dimensional structure of nitrogen dioxide can be sampled and tomographically reconstructed, providing valuable information on nitrogen dioxide emissions and downwind exposure, in addition to new understanding of boundary layer dynamics through the use of nitrogen dioxide as a tracer. Furthermore, certain aerosol information can be retrieved through absolute intensity measurements in each azimuthal direction supplemented by traditional techniques of O4 spectroscopy. Such measurements provide a new tool for boundary layer measurement and monitoring at a time when air quality implications on human health and climate are under significant scrutiny. This presentation will describe the instrument and tomographic potential of this technique. First measurements were taken as part of the international PEGASOS campaign in Bologna, Italy. Results from these measurements will be shown, including imaging of enhanced NO2 in the Bologna urban boundary layer during a severe thunderstorm. A Hemispherical Scanning Imaging DOAS instrument operating in Bologna, Italy in June 2012. Visible in the background

  6. Retrieve of atmospheric SO2 and O3 columns in the UV region using mobile DOAS

    International Nuclear Information System (INIS)

    Galicia, R.; La Rosa, J. de la; Stolik, S.

    2012-01-01

    We present the use of a passive DOAS system to retrieve SO2 and O3 columns emitted by industrial chimneys. It works with software built in LabVIEW and running with a PC linked to mini spectrometer and GPS. The system uses the sun light as light source, a telescope a fiber optic, a mini-spectrometer and a GPS. The spectrometer and the GPS are linked to a PC where the system is controlled and where all data are processed to retrieve the SO2 and O3 slant columns. (Author)

  7. Binding of doa kinase to specific loci in polytene chromosomes of Drosophila melanogaster

    Czech Academy of Sciences Publication Activity Database

    Kováčiková, M.; Raška, Ivan; Mateášik, A.; Chase, B. A.; Farkaš, R.

    2006-01-01

    Roč. 40, č. 1 (2006), s. 21-27 ISSN 1210-0668 R&D Projects: GA MŠk(CZ) LC535; GA ČR(CZ) GA304/02/0342 Grant - others:VEGA(SK) 2/3025/23; SAV(SK) APVT-51-027402; NSF(US) IBN-97-24006; US-SK(SK) 13/029/01 Institutional research plan: CEZ:AV0Z50110509 Keywords : specific protein kinases * DOA * polytene chromosomes Subject RIV: EB - Genetics ; Molecular Biology

  8. A Joint Audio-Visual Approach to Audio Localization

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    Localization of audio sources is an important research problem, e.g., to facilitate noise reduction. In the recent years, the problem has been tackled using distributed microphone arrays (DMA). A common approach is to apply direction-of-arrival (DOA) estimation on each array (denoted as nodes), a...... time-of-flight cameras. Moreover, we propose an optimal method for weighting such DOA and range information for audio localization. Our experiments on both synthetic and real data show that there is a clear, potential advantage of using the joint audiovisual localization framework....

  9. Direction of Radio Finding via MUSIC (Multiple Signal Classification) Algorithm for Hardware Design System

    Science.gov (United States)

    Zhang, Zheng

    2017-10-01

    Concept of radio direction finding systems, which use radio direction finding is based on digital signal processing algorithms. Thus, the radio direction finding system becomes capable to locate and track signals by the both. Performance of radio direction finding significantly depends on effectiveness of digital signal processing algorithms. The algorithm uses the Direction of Arrival (DOA) algorithms to estimate the number of incidents plane waves on the antenna array and their angle of incidence. This manuscript investigates implementation of the DOA algorithms (MUSIC) on the uniform linear array in the presence of white noise. The experiment results exhibit that MUSIC algorithm changed well with the radio direction.

  10. MAX-DOAS aerosol and trace gases measurements in megacities in China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xin [Institut fuer Energie- und Klimaforschung, Forschungszentrum Juelich (Germany); College of Environmental Science and Engineering Peking University, Beijing (China); Brauers, Theo [Institut fuer Energie- und Klimaforschung, Forschungszentrum Juelich (Germany); Shao, Min [College of Environmental Science and Engineering Peking University, Beijing (China)

    2011-07-01

    Multi Axis Differential Optical Absorption Spectroscopy (MAXDOAS) is a new remote sensing technique to measure atmospheric trace gases. Compared to other areas in the world, the atmospheric observations in megacities in China are rather limited. We present MAX-DOAS measurements at four sites in Beijing and Guangzhou in 2006 and 2008. At each site, the scattered sunlight was recorded at 7 elevation angles for about 1 months. Using the zenith spectrum as reference, the Differential Slant Column Densities (DSCDs) of HCHO, CHOCHO, O{sub 4} and NO{sub 2} at offaxis viewing geometries were derived from the DOAS fit. These DSCDs were simulated using a backward Monte Carlo radiative transfer model. The aerosol and trace gas profiles were defined by 3 parameters: the integrated quantities (T), the height of the surface layer (H), and the fraction of T below H. We fitted the modeled values to the measured values at the corresponding viewing geometries by varying the 3 parameters. The aerosol extinction and the boundary layer height were successfully retrieved from the measured O{sub 4} DSCDs as well as ground level concentrations of CHOCHO, HCHO, and NO{sub 2}, the latter being compared to simultaneous in-situ measurements.

  11. The research and development of an air pollutant monitoring system based on DOAS technology

    Science.gov (United States)

    Li, Hua; Liu, Han-peng; Zheng, Ming; Meng, Xiao-feng

    2009-07-01

    This article illuminates a kind of sensor used in measuring the concentrations of the main pollutants in flue gas streams (Dust, SO2 and NOx) based on the UV-DOAS technology in air pollutant monitoring. Using the high-level embedded microprocessors and complex programmable logic device, the sensor completes system measurement, management and signal communication, and spectrum inversion and data saving are processed by PC at the same time. Differential optical absorption spectroscopy (DOAS) technology is used in the flue gas pollutant factor analysis through the sensor construction. The absorption spectra of SO2, NOx and smoke dust are inverted to reduce the interference of other factors in flue gas streams. At the same time, the effect of light source fluctuation and optical transmission ratio is considered and removed in the measurement system. The result shows that the monitoring accuracy of concentration of sulfur dioxide and smoke dust achieves +/-2%, the concentration of nitrogen oxides accuracy achieves +/-3%, which meets the requirements of the national standard. The sensor can be directly installed in a flue. As a result, process of measuring is simplified and measurement accuracy is improved. Further more, this method increases the stability of the system and reduces the maintenance costs. Measurement data is transferred through data bus between the sensor and upper PC to realize remote control and real-time measurement. Considering the severe conditions in measuring the main pollutants in flue gas streams, applications of anti-interference and anti-corrosion etc. are taken in the system design.

  12. Remote sensing of stratospheric O3 and NO2 using a portable and compact DOAS spectrometer

    International Nuclear Information System (INIS)

    Raponi, M M; Wolfram, E; Quel, E J; Jimenez, R; Tocho, J O

    2011-01-01

    The use of passive and active remote sensing systems has largely contributed to advance our understanding of important atmospheric phenomena. Here we present a compact and portable passive DOAS (Differential Optical Absorption Spectroscopy) system, developed for measuring the vertical column density (VCD) of multiple atmospheric trace gases. We highlight the main characteristics of the system components: a mini-spectrometer (HR4000, Ocean Optics), two optical fibers (400 μm of core, 6 m and 25 cm of longitude), an external shutter and the control/data processing software. Nitrogen dioxide (NO 2 ) and ozone (O 3 ) VCDs are derived from solar spectra acquired during twilights (87 0 - 91 0 zenithal angles) using the DOAS technique. The analysis is carried out by solving the Beer-Lambert-Bouger (BLB) law for the main atmospheric absorbers at selected wavelength ranges. The algorithm minimizes the fitting residuals to the BLB law, having as unknown the slant column density (SCD) of the species to determine. We present measurements carried out at the Marambio Antarctic Base (64 0 14' 25'' S; 56 0 37' 21'' W, 197 m asl) during January - February 2008. In addition, we compare our results with co-located measurements performed with EVA, a visible absorption spectrometer of Instituto Nacional de Tecnica Aeroespacial (INTA, Spain), a Dobson spectrophotometer of Servicio Meteorologico Nacional (SMN, Argentine) and the Ozone Monitoring Instrument (OMI), on board AURA satellite.

  13. Development of 2-D-MAX-DOAS and retrievals of trace gases and aerosols optical properties

    Science.gov (United States)

    Ortega, Ivan

    Air pollution is a major problem worldwide that adversely a_ects human health, impacts ecosystems and climate. In the atmosphere, there are hundreds of important compounds participating in complex atmospheric reactions linked to air quality and climate. Aerosols are relevant because they modify the radiation balance, a_ect clouds, and thus Earth albedo. The amount of aerosol is often characterized by the vertical integral through the entire height of the atmosphere of the logarithm fraction of incident light that is extinguished called Aerosol Optical Depth (AOD). The AOD at 550 nm (AOD550) over land is 0.19 (multi annual global mean), and that over oceans is 0.13. About 43 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions, sample spatial scales that resemble satellite ground-pixels and atmospheric models, and help integrate remote sensing and in-situ observations to obtain optical closure on the effects of aerosols and trace gases in our changing environment. In this work, I present the recent development of the University of Colorado two dimensional (2-D) Multi-AXis Differential Optical Absorption Spectroscopy (2-D-MAX-DOAS) instrument to measure the azimuth and altitude distribution of trace gases and aerosol optical properties simultaneously with a single instrument. The instrument measures solar scattered light from any direction in the sky, including direct sun light in the hyperspectral domain. In Chapter 2, I describe the capabilities of 2-D measurements in the context of retrievals of azimuth distributions of nitrogen dioxide (NO2), formaldehyde (HCHO), and glyoxal (CHOCHO), which are precursors for tropospheric O3 and aerosols. The measurements were carried out during the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) campaign in Mainz, Germany and show the ability to bridge spatial scales to

  14. Stratospheric NO2 vertical profile retrieved from ground-based Zenith-Sky DOAS observations at Kiruna, Sweden

    Science.gov (United States)

    Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Pukite, Janis; Van Roozendael, Michel; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

    2014-05-01

    Stratospheric NO2 destroys ozone and acts as a buffer against halogen-catalyzed ozone loss through the formation of reservoir species (ClONO2, BrONO2). Since the importance of both mechanisms depends on the altitude, the investigation of stratospheric NO2 vertical distribution can provide more insight into the role of nitrogen compounds in the destruction of ozone. Here we present stratospheric NO2 vertical profiles retrieved from twilight ground-based zenith-sky DOAS observations at Kiruna, Sweden (68.84°N, 20.41°E) covering 1997 - 2013 periods. This instrument observes zenith scattered sunlight. The sensitivity for stratospheric trace gases is highest during twilight due to the maximum altitude of the scattering profile and the light path through the stratosphere, which vary with the solar zenith angle. The profiling algorithm, based on the Optimal Estimation Method, has been developed by IASB-BIRA and successfully applied at other stations (Hendrick et al., 2004). The basic principle behind this profiling approach is that during twilight, the mean Rayleigh scattering altitude scans the stratosphere rapidly, providing height-resolved information on the absorption by stratospheric NO2. In this study, the long-term evolution of the stratospheric NO2 profile at polar latitude will be investigated. Hendrick, F., B. Barret, M. Van Roozendael, H. Boesch, A. Butz, M. De Mazière, F. Goutail, C. Hermans, J.-C. Lambert, K. Pfeilsticker, and J.-P. Pommereau, Retrieval of nitrogen dioxide stratospheric profiles from ground-based zenith-sky UV-visible observations: Validation of the technique through correlative comparisons, Atmospheric Chemistry and Physics, 4, 2091-2106, 2004

  15. MAX-DOAS tropospheric nitrogen dioxide column measurements compared with the Lotos-Euros air quality model

    NARCIS (Netherlands)

    Vlemmix, T.; Eskes, H.J.; Piters, A.J.M.; Schaap, M.; Sauter, F.J.; Kelder, H.; Levelt, P.F.

    2015-01-01

    A 14-month data set of MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) tropospheric NO2 column observations in De Bilt, the Netherlands, has been compared with the regional air quality model Lotos-Euros. The model was run on a 7×7 km2 grid, the same resolution as the emission

  16. Experimental Validation of the Simulation Model of a DOAS Equipped with a Desiccant Wheel and a Vapor Compression Refrigeration System

    Directory of Open Access Journals (Sweden)

    Pedro J. Martínez

    2017-09-01

    Full Text Available A dedicated outdoor air system (DOAS can be designed to supply 100% of the outside air and meet the latent load of the room with dry air. The objectives of this study were to develop a model of a DOAS equipped with a desiccant wheel and a vapor-compression refrigeration system, build a prototype, validate the model with experimental data, and gain knowledge about the system operation. The test facility was designed with the desiccant wheel downstream of the cooling coil to take advantage of the operating principles of cooling coils and desiccants. A model of the DOAS was developed in the TRNSYS environment. The root mean standard error (RMSE was used for model validation by comparing the measured air and refrigerant properties with the corresponding calculated values. The results obtained with the developed model showed that the DOAS was able to maintain an indoor humidity ratio depending on outdoor conditions. Laboratory tests were also used to investigate the effect of changes in the regeneration air temperature and the process airflow rate on the process air humidity ratio at the outlet of the wheel. The results are consistent with the technical literature.

  17. Mobile MAX-DOAS observation of NO2 and comparison with OMI satellite data in the western coastal areas of the Korean peninsula.

    Science.gov (United States)

    Chong, Jihyo; Kim, Young J; Gu, Myojeong; Wagner, Thomas; Song, Chul H

    2016-01-01

    Ground-based MAX-DOAS measurements have been used to retrieve column densities of atmospheric absorbers such as NO2, SO2, HCHO, and O3. In this study, mobile MAX-DOAS measurements were conducted to map the 2-D distributions of atmospheric NO2 in the western coastal areas of the Korean peninsula. A Mini-MAX-DOAS instrument was mounted on the rooftop of a mobile lab vehicle with a telescope mounted parallel to the driving direction, pointing forward. The measurements were conducted from 21 to 24 December 2010 along the western coastal areas from Gomso harbor (35.59N, 126.61E) to Gunsan harbor (35.98N, 126.67E). During mobile MAX-DOAS observations, high elevation angles were used to avoid shades from nearby obstacles. For the determination of the tropospheric vertical column density (VCD), the air mass factor (AMF) was retrieved by the so-called geometric approximation. The NO2 VCDs from 20 and 45 degree elevation angles were retrieved from mobile MAX-DOAS measurements. The tropospheric NO2 VCDs derived from mobile MAX-DOAS measurements were compared directly to those retrieved by the OMI satellite observations. Mobile MAX-DOAS VCD was in good agreement with OMI tropospheric VCD on most days. However, OMI tropospheric VCD was much higher than that of mobile MAX-DOAS on 23 December 2010. One probable reason for this difference is that OMI retrieval might overestimate NO2 VCD under haze conditions, when a pollution plume was transported over the measurement site. The mobile MAX-DOAS observations reveal much finer spatial patterns of NO2 distributions, which can provide useful information for the validation of satellite observation of atmospheric trace gases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. MAX-DOAS observations of aerosols, formaldehyde and nitrogen dioxide in the Beijing area: comparison of two profile retrieval approaches

    Directory of Open Access Journals (Sweden)

    T. Vlemmix

    2015-02-01

    Full Text Available A 4-year data set of MAX-DOAS observations in the Beijing area (2008–2012 is analysed with a focus on NO2, HCHO and aerosols. Two very different retrieval methods are applied. Method A describes the tropospheric profile with 13 layers and makes use of the optimal estimation method. Method B uses 2–4 parameters to describe the tropospheric profile and an inversion based on a least-squares fit. For each constituent (NO2, HCHO and aerosols the retrieval outcomes are compared in terms of tropospheric column densities, surface concentrations and "characteristic profile heights" (i.e. the height below which 75% of the vertically integrated tropospheric column density resides. We find best agreement between the two methods for tropospheric NO2 column densities, with a standard deviation of relative differences below 10%, a correlation of 0.99 and a linear regression with a slope of 1.03. For tropospheric HCHO column densities we find a similar slope, but also a systematic bias of almost 10% which is likely related to differences in profile height. Aerosol optical depths (AODs retrieved with method B are 20% high compared to method A. They are more in agreement with AERONET measurements, which are on average only 5% lower, however with considerable relative differences (standard deviation ~ 25%. With respect to near-surface volume mixing ratios and aerosol extinction we find considerably larger relative differences: 10 ± 30, −23 ± 28 and −8 ± 33% for aerosols, HCHO and NO2 respectively. The frequency distributions of these near-surface concentrations show however a quite good agreement, and this indicates that near-surface concentrations derived from MAX-DOAS are certainly useful in a climatological sense. A major difference between the two methods is the dynamic range of retrieved characteristic profile heights which is larger for method B than for method A. This effect is most pronounced for HCHO, where retrieved profile shapes with method

  19. Tropospheric nitrogen dioxide column retrieval based on ground-based zenith-sky DOAS observations

    Science.gov (United States)

    Tack, F. M.; Hendrick, F.; Pinardi, G.; Fayt, C.; Van Roozendael, M.

    2013-12-01

    A retrieval approach has been developed to derive tropospheric NO2 vertical column amounts from ground-based zenith-sky measurements of scattered sunlight. Zenith radiance spectra are observed in the visible range by the BIRA-IASB Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument and analyzed by the DOAS technique, based on a least-squares spectral fitting. In recent years, this technique has shown to be a well-suited remote sensing tool for monitoring atmospheric trace gases. The retrieval algorithm is developed and validated based on a two month dataset acquired from June to July 2009 in the framework of the Cabauw (51.97° N, 4.93° E) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). Once fully operational, the retrieval approach can be applied to observations from stations of the Network for the Detection of Atmospheric Composition Change (NDACC). The obtained tropospheric vertical column amounts are compared with the multi-axis retrieval from the BIRA-IASB MAX-DOAS instrument and the retrieval from a zenith-viewing only SAOZ instrument (Système d'Analyse par Observations Zénithales), owned by Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). First results show a good agreement for the whole time series with the multi-axis retrieval (R = 0.82; y = 0.88x + 0.30) as well as with the SAOZ retrieval (R = 0.85; y = 0.76x + 0.28 ). Main error sources arise from the uncertainties in the determination of tropospheric and stratospheric air mass factors, the stratospheric NO2 abundances and the residual amount in the reference spectrum. However zenith-sky measurements have been commonly used over the last decades for stratospheric monitoring, this study also illustrates the suitability for retrieval of tropospheric column amounts. As there are long time series of zenith-sky acquisitions available, the developed approach offers new perspectives with regard to the use of observations from the NDACC

  20. Sterol homeostasis requires regulated degradation of squalene monooxygenase by the ubiquitin ligase Doa10/Teb4

    DEFF Research Database (Denmark)

    Foresti, Ombretta; Ruggiano, Annamaria; Hannibal-Bach, Hans K

    2013-01-01

    Sterol homeostasis is essential for the function of cellular membranes and requires feedback inhibition of HMGR, a rate-limiting enzyme of the mevalonate pathway. As HMGR acts at the beginning of the pathway, its regulation affects the synthesis of sterols and of other essential mevalonate......-derived metabolites, such as ubiquinone or dolichol. Here, we describe a novel, evolutionarily conserved feedback system operating at a sterol-specific step of the mevalonate pathway. This involves the sterol-dependent degradation of squalene monooxygenase mediated by the yeast Doa10 or mammalian Teb4, a ubiquitin...... ligase implicated in a branch of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway. Since the other branch of ERAD is required for HMGR regulation, our results reveal a fundamental role for ERAD in sterol homeostasis, with the two branches of this pathway acting together...

  1. NO2 and HCHO variability in Mexico City from MAX-DOAS measurements

    Science.gov (United States)

    Grutter, M.; Friedrich, M. M.; Rivera, C. I.; Arellano, E. J.; Stremme, W.

    2015-12-01

    Atmospheric studies in large cities are of great relevance since pollution affects air quality and human health. A network of Multi Axis Differential Optical Absorption Spectrometers (MAX-DOAS) has been established in strategic sites within the Mexico City metropolitan area. Four instruments are now in operation with the aim to study the variability and spatial distribution of key pollutants, providing results of O4, NO2 and HCHO slant column densities (SCD). A numerical code has been written to retrieve gas profiles of NO2 and HCHO using radiative transfer simulations. We present the first results of the variability of these trace gases which will bring new insight in the current knowledge of transport patterns, emissions as well as frequency and origin of extraordinary events. Results of the vertical column densities (VCD) valiability of NO2 and HCHO in Mexico City are presented. These studies are useful to validate current and future satellite observatopns such as OMI, TROPOMI and TEMPO.

  2. DOAS measurements of NO2 from an ultralight aircraft during the Earth Challenge expedition

    Directory of Open Access Journals (Sweden)

    O. Ronveaux

    2012-08-01

    Full Text Available We report on airborne Differential Optical Absorption Spectroscopy (DOAS measurements of NO2 tropospheric columns above South Asia, the Arabic peninsula, North Africa, and Italy in November and December 2009. The DOAS instrument was installed on an ultralight aircraft involved in the Earth Challenge project, an expedition of seven pilots flying on four ultralight aircraft between Australia and Belgium. The instrument recorded spectra in limb geometry with a large field of view, a set-up which provides a high sensitivity to the boundary layer NO2 while minimizing the uncertainties related to the attitude variations. We compare our measurements with OMI (Ozone Monitoring Instrument and GOME-2 (Global Ozone Monitoring Experiment 2 tropospheric NO2 products when the latter are available. Above Rajasthan and the Po Valley, two areas where the NO2 field is homogeneous, data sets agree very well. Our measurements in these areas are 0.1 ± 0.1 to 3 ± 1 × 1015 molec cm−2 and 2.6 ± 0.8 × 1016 molec cm−2, respectively. Flying downwind of Riyadh, our NO2 measurements show the structure of the megacity's exhaust plume with a higher spatial resolution than OMI. Moreover, our measurements are larger (up to 40% than those seen by satellites. We also derived tropospheric columns when no satellite data were available if it was possible to get information on the visibility from satellite measurements of aerosol optical thickness. This experiment also provides a confirmation for the recent finding of a soil signature above desert.

  3. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

    Directory of Open Access Journals (Sweden)

    L. Molina

    2009-08-01

    Full Text Available We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2 kg/s of HCHO and 4.4 (4.0–5.0 kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73 kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

  4. Global carbon monoxide as retrieved from SCIAMACHY by WFM-DOAS

    Directory of Open Access Journals (Sweden)

    M. Buchwitz

    2004-01-01

    Full Text Available First results concerning the retrieval of tropospheric carbon monoxide (CO from satellite solar backscatter radiance measurements in the near-infrared spectral region (~2.3µm are presented. The Weighting Function Modified (WFM DOAS retrieval algorithm has been used to retrieve vertical columns of CO from SCIAMACHY/ENVISAT nadir spectra. We present detailed results for three days from the time periode January to October 2003 selected to have good overlap with the daytime CO measurements of MOPITT onboard EOS Terra. Because the WFM-DOAS Version 0.4 CO columns presented in this paper are scaled by a constant factor of 0.5 to compensate for an obvious overestimation we focus on the variability of the retrieved columns rather than on their absolute values. It is shown that plumes of CO resulting from, e.g. biomass burning in Africa, are detectable with single overpass SCIAMACHY data. Globally, the SCIAMACHY CO columns are in reasonable agreement with the Version 3 CO column data product of MOPITT. For example, for measurements over land, where the quality of the data is typically better than over ocean due to higher surface reflectivity, the standard deviation of the difference with respect to MOPITT is in the range 0.4-0.6x1018 molecules/cm2 and the linear correlation coefficient is between 0.4 and 0.7. The level of agreement between the data of both sensors depends on time and location but is typically within 30% for most latitudes. In the southern hemisphere outside Antarctica SCIAMACHY tends to give systematically higher values than MOPITT. More studies are needed to find out what the reasons for the observed differences with respect to MOPITT are and how the algorithm can be modified to improve the quality of the CO columns as retrieved from SCIAMACHY.

  5. A Conserved C-terminal Element in the Yeast Doa10 and Human MARCH6 Ubiquitin Ligases Required for Selective Substrate Degradation.

    Science.gov (United States)

    Zattas, Dimitrios; Berk, Jason M; Kreft, Stefan G; Hochstrasser, Mark

    2016-06-03

    Specific proteins are modified by ubiquitin at the endoplasmic reticulum (ER) and are degraded by the proteasome, a process referred to as ER-associated protein degradation. In Saccharomyces cerevisiae, two principal ER-associated protein degradation ubiquitin ligases (E3s) reside in the ER membrane, Doa10 and Hrd1. The membrane-embedded Doa10 functions in the degradation of substrates in the ER membrane, nuclear envelope, cytoplasm, and nucleoplasm. How most E3 ligases, including Doa10, recognize their protein substrates remains poorly understood. Here we describe a previously unappreciated but highly conserved C-terminal element (CTE) in Doa10; this cytosolically disposed 16-residue motif follows the final transmembrane helix. A conserved CTE asparagine residue is required for ubiquitylation and degradation of a subset of Doa10 substrates. Such selectivity suggests that the Doa10 CTE is involved in substrate discrimination and not general ligase function. Functional conservation of the CTE was investigated in the human ortholog of Doa10, MARCH6 (TEB4), by analyzing MARCH6 autoregulation of its own degradation. Mutation of the conserved Asn residue (N890A) in the MARCH6 CTE stabilized the normally short lived enzyme to the same degree as a catalytically inactivating mutation (C9A). We also report the localization of endogenous MARCH6 to the ER using epitope tagging of the genomic MARCH6 locus by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome editing. These localization and CTE analyses support the inference that MARCH6 and Doa10 are functionally similar. Moreover, our results with the yeast enzyme suggest that the CTE is involved in the recognition and/or ubiquitylation of specific protein substrates. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Elevated aerosol layers modify the O2–O2 absorption measured by ground-based MAX-DOAS

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Ivan; Berg, Larry K.; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

    2016-06-01

    The oxygen collisional complex (O2-O2, or O4) is a greenhouse gas, and a calibration trace gas used to infer aerosol and cloud properties by Differential Optical Absorption Spectroscopy (DOAS). Recent reports suggest the need for an O4 correction factor (CFO4) when comparing simulated and measured O4 differential slant column densities (dSCD) by passive DOAS. We investigate the sensitivity of O4 dSCD simulations at ultraviolet (360 nm) and visible (477 nm) wavelengths towards separately measured aerosol extinction profiles. Measurements were conducted by the University of Colorado 2D-MAX-DOAS instrument and NASA’s multispectral High Spectral Resolution Lidar (HSRL-2) during the Two Column Aerosol Project (TCAP) at Cape Cod, MA in July 2012. During two case study days with (1) high aerosol load (17 July, AOD ~ 0.35 at 477 nm), and (2) near molecular scattering conditions (22 July, AOD < 0.10 at 477 nm) the measured and calculated O4 dSCDs agreed within 6.4±0.4% (360 nm) and 4.7±0.6% (477 nm) if the HSRL-2 profiles were used as input to the calculations. However, if in the calculations the aerosol is confined to the surface layer (while keeping AOD constant) we find 0.53DOAS. Opportunities to identify and better characterize these layers are also discussed.

  7. Bioética e Doação e Transplante de Órgãos

    OpenAIRE

    Goldim, José Roberto

    2016-01-01

    Slide presentation about Bioethics, Organ Donations and Transplants. A brief review about ethical issues retated to organ transplantation.Apresentação de diapositivos sobre Bioética, Doação e Transplante de Órgãos. É uma breve apresentação dobre os aspectos éticos relacionados ao transplante de órgãos. 

  8. MAX-DOAS measurements of NO2, HCHO and CHOCHO at a rural site in Southern China

    Science.gov (United States)

    Li, X.; Brauers, T.; Hofzumahaus, A.; Lu, K.; Li, Y. P.; Shao, M.; Wagner, T.; Wahner, A.

    2013-02-01

    We performed MAX-DOAS measurements during the PRIDE-PRD2006 campaign in the Pearl River Delta region (PRD), China, for 4 weeks in July 2006 at a site located 60 km north of Guangzhou. The vertical distributions of NO2, HCHO, and CHOCHO were independently retrieved by an automated iteration method. The NO2 mixing ratios measured by MAX-DOAS showed reasonable agreement with the simultaneous, ground based in-situ data. The tropospheric NO2 vertical column densities (VCDs) observed by OMI on board EOS-Aura satellite were higher than with those by MAX-DOAS. The 3-D chemical transport model CMAQ overestimated the NO2 VCDs as well as the surface concentrations by about 65%. From this observation, a reduction of NOx emission strength in CMAQ seems to be necessary in order to well reproduce the NO2 observations. The average mixing ratios of HCHO and CHOCHO were 7 ppb and 0.4 ppb, respectively, higher than in other rural or semirural environments. The high ratio of 0.062 between CHOCHO and HCHO corresponds to the high VOCs reactivity and high HOx turnover rate consistent with other observations during the campaign.

  9. Doação de órgãos: é preciso educar para avançar

    Directory of Open Access Journals (Sweden)

    Taise Ribeiro Morais

    Full Text Available O estudo refere-se a uma das principais dificuldades encontradas no processo de doação de órgãos: a deficiência de educação continuada específica para doação por parte da população e dos profissionais de saúde. Teve como objetivo enfatizar como a educação influi positivamente nas estatísticas de doações de órgãos. Trata-se de uma revisão bibliográfica, incluindo artigos de periódicos eletrônicos e obras literárias. Existe uma grande diferença entre o número de pessoas esperando transplante e o número de doadores. Medidas de educação contínua e políticas de saúde pública que incentivem as pessoas a manifestar o desejo de serem doadoras são estratégias importantes para amenizar esse problema.

  10. Tracking of Multiple Moving Sources Using Recursive EM Algorithm

    Directory of Open Access Journals (Sweden)

    Böhme Johann F

    2005-01-01

    Full Text Available We deal with recursive direction-of-arrival (DOA estimation of multiple moving sources. Based on the recursive EM algorithm, we develop two recursive procedures to estimate the time-varying DOA parameter for narrowband signals. The first procedure requires no prior knowledge about the source movement. The second procedure assumes that the motion of moving sources is described by a linear polynomial model. The proposed recursion updates the polynomial coefficients when a new data arrives. The suggested approaches have two major advantages: simple implementation and easy extension to wideband signals. Numerical experiments show that both procedures provide excellent results in a slowly changing environment. When the DOA parameter changes fast or two source directions cross with each other, the procedure designed for a linear polynomial model has a better performance than the general procedure. Compared to the beamforming technique based on the same parameterization, our approach is computationally favorable and has a wider range of applications.

  11. Preliminary Assessment about Genetic Diversity, the Stability of Potential Mutants from Two Varieties of Chrysanthemum morifolium Ramat. (Bronze Doa and Purple Farm) via Gamma Irradiation

    International Nuclear Information System (INIS)

    Nguyen Tuong Mien; Le Ngoc Trieu; Le Tien Thanh; Pham Van Nhi; Huynh Thi Trung

    2013-01-01

    The aim of this study was to evidence the efficiency of irradiation by gamma ray from 60 Co source on chrysanthemum artificial seeds, through that select a number of potential mutants from two varieties of Chrysanthemum morifolium Ramat artificial seeds (Bronze and purple chrysanthemum). The experimental result showed that LD 50 for the Bronze Doa variety was 50 Gy and Purple Farm variety was 100 Gy. Irradiated in vitro artificial seeds were transferred into fresh MS medium and placed in the growth room with three replications at each of dose. The completed in vitro plants were transplanted into ex vitro condition in green house. After 30 days in the greenhouse, survival rate of plantlets were and growth in 20 Gy and 40 Gy for Purple chrysanthemum, while the number of survival Bronze chrysanthemum plantlets were reduced gradually toward the increasing of gamma doses. In this study, on farm, through screening 18 phenotypic mutants of both chrysanthemums were recorded and collected including 6 potential mutants that selected for next research based on their phenotypic differences to the originals, their aesthetic and low mosaic. These 6 potential mutants together with their original varieties were micro-propagated to induce the potential mutant lines for estimation on farm of mutant characteristic segregation rates. (author)

  12. Off-axis Doas Measurements At Observatoire De Haute Provence During 2001

    Science.gov (United States)

    Roozendael, M. Van; de Mazière, M.; Fayt, C.; Hendrick, F.; Hermans, C.

    Since December 2000, a ground-based off-axis DOAS spectrometer has been operated by BIRA-IASB in the South of France at the Observatoire de Haute Provence (OHP, 44°N). The design of the instrument allows automated observations of the scattered light alternatively in the zenith direction and at 10° above the horizon (off-axis geometry). The spectrometer is polarised and follows the azimuth of the sun. Its temperature is regulated and it is equipped with a Princeton Instruments/ Hammamatsu cooled diode array detector. Observations are made every 5 minutes in the 320-390 nm range. The analysis of the spectra recorded between January and December 2001 demonstrates the sensitivity of the measurements to tropospheric contents of NO2, HCHO, O3 and BrO. Results show a large seasonality in the HCHO content with maximum values in summer. The tropospheric BrO column is found to be stable over the year in the range of approximately 1.5-2 x1013 molec/cm2, roughly consistent with GOME observations at Northern mid-latitudes. Large increases of the BrO concentration are observed in summer likely due to local pollution in the vicinity of the station.

  13. Forest Fire Finder - DOAS application to long-range forest fire detection

    Science.gov (United States)

    Valente de Almeida, Rui; Vieira, Pedro

    2017-06-01

    Fires are an important factor in shaping Earth's ecosystems. Plant and animal life, in almost every land habitat, are at least partially dependent on the effects of fire. However, their destructive force, which has often proven uncontrollable, is one of our greatest concerns, effectively resulting in several policies in the most important industrialised regions of the globe. This paper aims to comprehensively characterise the Forest Fire Finder (FFF), a forest fire detection system based mainly upon a spectroscopic technique called differential optical absorption spectroscopy (DOAS). The system is designed and configured with the goal of detecting higher-than-the-horizon smoke columns by measuring and comparing scattered sunlight spectra. The article covers hardware and software, as well as their interactions and specific algorithms for day mode operation. An analysis of data retrieved from several installations deployed in the course of the last 5 years is also presented. Finally, this paper features a discussion on the most prominent future improvements planned for the system, as well as its ramifications and adaptations, such as a thermal imaging system for short-range fire seeking or environmental quality control.

  14. Sterol homeostasis requires regulated degradation of squalene monooxygenase by the ubiquitin ligase Doa10/Teb4

    Science.gov (United States)

    Foresti, Ombretta; Ruggiano, Annamaria; Hannibal-Bach, Hans K; Ejsing, Christer S; Carvalho, Pedro

    2013-01-01

    Sterol homeostasis is essential for the function of cellular membranes and requires feedback inhibition of HMGR, a rate-limiting enzyme of the mevalonate pathway. As HMGR acts at the beginning of the pathway, its regulation affects the synthesis of sterols and of other essential mevalonate-derived metabolites, such as ubiquinone or dolichol. Here, we describe a novel, evolutionarily conserved feedback system operating at a sterol-specific step of the mevalonate pathway. This involves the sterol-dependent degradation of squalene monooxygenase mediated by the yeast Doa10 or mammalian Teb4, a ubiquitin ligase implicated in a branch of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway. Since the other branch of ERAD is required for HMGR regulation, our results reveal a fundamental role for ERAD in sterol homeostasis, with the two branches of this pathway acting together to control sterol biosynthesis at different levels and thereby allowing independent regulation of multiple products of the mevalonate pathway. DOI: http://dx.doi.org/10.7554/eLife.00953.001 PMID:23898401

  15. Retrieval of Vertical Aerosol and Trace Gas Distributions from Polarization Sensitive Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

    Science.gov (United States)

    Tirpitz, Jan-Lukas; Friess, Udo; Platt, Ulrich

    2017-04-01

    An accurate knowledge of the vertical distribution of trace gases and aerosols is crucial for our understanding of the chemical and dynamical processes in the lower troposphere. Their accurate determination is typically only possible by means of laborious and expensive airborne in-situ measurements but in the recent decades, numerous promising ground-based remote sensing approaches have been developed. One of them is to infer vertical distributions from "Differential Optical Absorption Spectroscopy" (DOAS) measurements. DOAS is a technique to analyze UV- and visible radiation spectra of direct or scattered sunlight, which delivers information on different atmospheric parameters, integrated over the light path from space to the instrument. An appropriate set of DOAS measurements, recorded under different viewing directions (Multi-Axis DOAS) and thus different light path geometries, provides information on the atmospheric state. The vertical profiles of aerosol properties and trace gas concentrations can be retrieved from such a set by numerical inversion techniques, incorporating radiative transfer models. The information content of measured data is rarely sufficient for a well-constrained retrieval, particularly for atmospheric layers above 1 km. We showed in first simulations that, apart from spectral properties, the polarization state of skylight is likely to provide a significant amount of additional information on the atmospheric state and thus to enhance retrieval quality. We present first simulations, expectations and ideas on how to implement and characterize a polarization sensitive Multi-Axis DOAS instrument and a corresponding profile retrieval algorithm.

  16. Doação de órgãos e tecidos: relação com o corpo em nossa sociedade

    OpenAIRE

    Roza,Bartira De Aguiar; Garcia,Valter Duro; Barbosa,Sayonara de Fátima Faria; Mendes,Karina Dal Sasso; Schirmer,Janine

    2010-01-01

    Este estudo, de revisão bibliográfica, objetivou tecer considerações teóricas sobre doação de órgãos e tecidos e sua relação com o corpo em nossa sociedade. O aumento da taxa de doação depende de um olhar ampliado além das questões técnicas do processo de doação de órgãos e tecidos. Vários países, com larga experiência temporal e, que trabalham sistematicamente nesse processo, incorporaram a abordagem social e a perspectiva ética, baseadas no voluntarismo das famílias e no respeito ao direito...

  17. Optimización de la Estimación de DOA en Sistemas de Antenas Inteligentes usando criterios de Redes Neuronales

    Directory of Open Access Journals (Sweden)

    Serguei Guerra Fernández

    2013-04-01

    Full Text Available La estimación DOA es uno de los principales problemas a resolver en las comunicaciones modernas. En el presente trabajo, se realiza un acercamiento a los sistemas de Antenas Inteligentes y los elementos teóricos referidos a la estimación de DOA, ecuaciones y modelos. Se estudian los métodos clásicos de estimación y las nuevas técnicas basadas en Redes Neuronales. Se traza una metodología para la obtención de resultados, a partir de parámetros medibles, en cada uno de los algoritmos de estimación sometidos a comparación. Finalmente, se analizan los resultados y se propone utilizar técnicas basadas en Redes Neuronales a fin de mejorar la estimación de DOA en Antenas Inteligentes.

  18. Humanização no processo de doação para transplante na perspectiva de enfermeiros de Unidades de Terapia Intensiva

    OpenAIRE

    Lúcia Piva Cabral Senna

    2014-01-01

    Introdução: O processo de doação de órgãos envolve assistência aos potenciais doadores e aos seus familiares. A humanização nesse contexto requer o envolvimento dos profissionais que participam das diversas atividades desenvolvidas e, dentre eles, os enfermeiros de Unidades de Terapia Intensiva. Objetivo: Conhecer a percepção de enfermeiros de unidades de terapia intensiva sobre a humanização no processo de doação de órgãos para transplante. Método: Trata-se de um estudo exploratório, descri...

  19. Recusa de doação de órgãos e tecidos para transplante relatados por familiares de potenciais doadores

    OpenAIRE

    Moraes,Edvaldo Leal de; Massarollo,Maria Cristina Komatsu Braga

    2009-01-01

    OBJETIVO: Conhecer a percepção de familiares de potenciais doadores sobre os motivos de recusa para doação de órgãos e tecidos para transplante. MÉTODOS: Trata-se de uma pesquisa qualitativa, na vertente fenomenológica, modalidade "estrutura do fenômeno situado". Participaram do estudo oito familiares que recusaram a doação dos órgãos e tecidos. RESULTADOS: Após análise das entrevistas, foram revelados dez motivos de recusa, considerados pelos familiares. CONSIDERAÇÕES FINAIS: As proposições ...

  20. Spektroskopische (DOAS)-Langzeitmessungen von Ozon und Vorlaeufersubstanzen an der Ostseekuestenstation Arkona. Abschlussbericht; Long term spectroscopic (DOAS) measurement of ozone and related species at the Baltic coast station Arkona. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, R [Institut fuer Troposphaerenforschung e.V. (IfT), Leipzig (Germany); Flentje, H [Institut fuer Troposphaerenforschung e.V. (IfT), Leipzig (Germany); Heintz, F [Heidelberg Univ. (Germany). Inst. fuer Umweltphysik; Karbach, H J [Institut fuer Troposphaerenforschung e.V. (IfT), Leipzig (Germany); Stutz, J [Heidelberg Univ. (Germany). Inst. fuer Umweltphysik; Platt, U [Heidelberg Univ. (Germany). Inst. fuer Umweltphysik

    1996-08-01

    Boundary layer ozone concentrations have been recorded since 1956 by the German Weather Service, (MD / DWD) at Cape Arkona, Island of Ruegen, GDR / FRG. In April 1993, a Long Path Differential Optical Absorption Spectrometer (LP-DOAS) was set up near the DWD-site. Measurements of the concentrations of O{sub 3}, NO{sub 2}, NO{sub 3} and SO{sub 2} were carried out with a newly developed DOAS system. The system incorporates two coaxially arranged Newton-type telescopes, a flat field holographic grating spectrometer and a retro reflector array. Combining the meteorological data with ozone and other gas concentrations, sector-classified results are used to identify the constraints for future evaluations of regional long-term trends of ozone concentrations. A statistical analysis of different trace gases for the periods summer, autumn, winter and spring is prepared. The long term nitrate radicals data record is used to retrieve information on the production rate of nitrate radicals, its lifetime, and possible depletion mechanism. (orig.)

  1. Remote sensing of stratospheric O{sub 3} and NO{sub 2} using a portable and compact DOAS spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Raponi, M M; Wolfram, E; Quel, E J [Division LIDAR, Centro de Investigaciones en Laseres y Aplicaciones, CEILAP (CITEFA-CONICET), Juan B. de La Salle 4397 (B1603ALO), Villa Martelli, Buenos Aires (Argentina); Jimenez, R [Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogota (Colombia); Tocho, J O, E-mail: mraponi@citefa.gov.ar [Centro de Investigaciones Opticas, CIOp (CONICET La Plata-CIC), Buenos Aires (Argentina)

    2011-01-01

    The use of passive and active remote sensing systems has largely contributed to advance our understanding of important atmospheric phenomena. Here we present a compact and portable passive DOAS (Differential Optical Absorption Spectroscopy) system, developed for measuring the vertical column density (VCD) of multiple atmospheric trace gases. We highlight the main characteristics of the system components: a mini-spectrometer (HR4000, Ocean Optics), two optical fibers (400 {mu}m of core, 6 m and 25 cm of longitude), an external shutter and the control/data processing software. Nitrogen dioxide (NO{sub 2}) and ozone (O{sub 3}) VCDs are derived from solar spectra acquired during twilights (87{sup 0} - 91{sup 0} zenithal angles) using the DOAS technique. The analysis is carried out by solving the Beer-Lambert-Bouger (BLB) law for the main atmospheric absorbers at selected wavelength ranges. The algorithm minimizes the fitting residuals to the BLB law, having as unknown the slant column density (SCD) of the species to determine. We present measurements carried out at the Marambio Antarctic Base (64{sup 0} 14' 25'' S; 56{sup 0} 37' 21'' W, 197 m asl) during January - February 2008. In addition, we compare our results with co-located measurements performed with EVA, a visible absorption spectrometer of Instituto Nacional de Tecnica Aeroespacial (INTA, Spain), a Dobson spectrophotometer of Servicio Meteorologico Nacional (SMN, Argentine) and the Ozone Monitoring Instrument (OMI), on board AURA satellite.

  2. The influence of scattering and absorption processes in sea water on atmospheric radiation - results from ship-borne DOAS measurements

    Energy Technology Data Exchange (ETDEWEB)

    Schoenhardt, Anja; Wittrock, Folkard; Richter, Andreas; Kirk, Henning; Schulte, Hagen I.D.B; Burrows, John P. [Institut fuer Umweltphysik, Universitaet Bremen (Germany)

    2009-07-01

    Absorption and inelastic scattering within water can influence the upwelling radiation over water bodies. If not identified properly, these effects impact on absorption measurements of trace gases when using nadir observations. Spectral correlations lead to incorrect trace gas amounts and reduced retrieval quality. This presentation reports on Differential Optical Absorption Spectroscopy (DOAS) measurements from a Polarstern cruise in April-May 2008 from South America to Europe. Scattered sun light was measured by two spectrometer units in the visible and UV spectral regions. The light collecting telescope was viewing alternately in different elevation angles: into zenith-sky and at slant angles above and especially below the horizon, intentionally viewing into the ocean water. The DOAS measurements were analysed in different spectral windows to identify structures not associated to well-known effects. Such persistent structures were indeed found in spectra at water viewing angles and may be caused by inelastic scattering at water molecules, by effects from substances in the water (particles, organics, etc) or by processes yet unknown. Analysing these structured residuals helps to characterise the disturbance of optical absorption measurements caused by light transmission through sea water.

  3. Doação e fila de transplante de córnea no Estado do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Gustavo Bonfadini

    2014-08-01

    Full Text Available O presente trabalho objetiva descrever o processo de doação, captação, fila de espera e transplante de órgãos e tecidos como uma das políticas de saúde no Brasil e no Estado do Rio de Janeiro, com ênfase nos procedimentos relativos aos transplantes de córnea. A baixa notificação de possíveis doadores e a alta taxa de negativa familiar na doação associado ao insuficiente número de córneas disponibilizadas por Banco de Olhos são os principais fatores que limitam o aumento do número dos transplantes de córnea no Brasil. A criação do Banco de Olhos do Rio de Janeiro, associado a politicas que estimulam o aumento da notificação e captação de córneas visa diminuir a fila de espera para transplante de córnea no Estado.

  4. Perspectives of 2D and 3D mapping of atmospheric pollutants over urban areas by means of airborne DOAS spectrometers

    Directory of Open Access Journals (Sweden)

    F. Ravegnani

    2006-06-01

    Full Text Available tants, offering numerous advantages over conventional networks of in situ analysers. We propose some innovative solutions in the field of DOAS (Differential Optical Absorption Spectroscopy remote systems, utilizing diffuse solar light as the radiation source. We examine the numerous potentialities of minor gas slant column calculations, applying the «off-axis» methodology for collecting the diffuse solar radiation. One of these particular approaches, using measurements along horizontal paths, has already been tested with the spectrometer installed on board the Geophysica aircraft during stratospheric flights up to altitudes of 20 km. The theoretical basis of these new measurement techniques using DOAS remote sensing systems are delineated to assess whether low altitude flights can provide 2D and 3D pollution tomography over metropolitan areas. The 2D or 3D trace gas total column mapping could be used to investigate: i transport and dispersion phenomena of air pollution, ii photochemical process rates, iii gas plume tomography, iv minor gas vertical profiles into the Planetary Boundary Layer and v minor gas flux divergence over a large area.

  5. Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS

    Directory of Open Access Journals (Sweden)

    W. R. Simpson

    2017-08-01

    Full Text Available Heterogeneous photochemistry converts bromide (Br− to reactive bromine species (Br atoms and bromine monoxide, BrO that dominate Arctic springtime chemistry. This phenomenon has many impacts such as boundary-layer ozone depletion, mercury oxidation and deposition, and modification of the fate of hydrocarbon species. To study environmental controls on reactive bromine events, the BRomine, Ozone, and Mercury EXperiment (BROMEX was carried out from early March to mid-April 2012 near Barrow (Utqiaġvik, Alaska. We measured horizontal and vertical gradients in BrO with multiple-axis differential optical absorption spectroscopy (MAX-DOAS instrumentation at three sites, two mobile and one fixed. During the campaign, a large crack in the sea ice (an open lead formed pushing one instrument package ∼ 250 km downwind from Barrow (Utqiaġvik. Convection associated with the open lead converted the BrO vertical structure from a surface-based event to a lofted event downwind of the lead influence. The column abundance of BrO downwind of the re-freezing lead was comparable to upwind amounts, indicating direct reactions on frost flowers or open seawater was not a major reactive bromine source. When these three sites were separated by ∼ 30 km length scales of unbroken sea ice, the BrO amount and vertical distributions were highly correlated for most of the time, indicating the horizontal length scales of BrO events were typically larger than ∼ 30 km in the absence of sea ice features. Although BrO amount and vertical distribution were similar between sites most of the time, rapid changes in BrO with edges significantly smaller than this ∼ 30 km length scale episodically transported between the sites, indicating BrO events were large but with sharp edge contrasts. BrO was often found in shallow layers that recycled reactive bromine via heterogeneous reactions on snowpack. Episodically, these surface-based events propagated aloft when

  6. A doação renal em textos científicos: entre as metáforas do presente e da mercadoria

    Directory of Open Access Journals (Sweden)

    Luciana Freitas Fernandes

    2011-09-01

    Full Text Available Este trabalho de revisão analisa a produção discursiva sobre o transplante renal com doador vivo, buscando compreender os repertórios interpretativos da doação renal intervivos construídos e disseminados na literatura médica, mediante análise de uma seleção de artigos científicos. Analisaram-se 89 artigos veiculados, entre 1999 e 2010, em periódicos internacionais. A análise destaca um conjunto de tópicos que podem ser enquadrados em dois eixos: aspectos psicossociais da doação e estratégias de ampliação do número de doadores vivos. Esses eixos ancoram-se nas metáforas do "presente" e da "mercadoria", ambas a serviço da promoção da doação de órgãos e com efeitos específicos. A metáfora do presente constrange os indivíduos à doação espontânea e altruísta; a da mercadoria constrói o corpo como um conjunto de partes recicláveis, passíveis de troca comercial.

  7. Percepção do corpo, medo da morte, religião e doação de órgãos

    Directory of Open Access Journals (Sweden)

    Bendassolli Pedro Fernando

    2001-01-01

    Full Text Available O objetivo desta pesquisa foi o de levantar as principais razões que levam estudantes universitários a doarem seus órgãos para transplante e as relações entre a doação de órgãos, o medo da morte e a religião dos participantes. Para tanto, foram realizados três estudos interdependentes, os quais somaram a participação de 192 estudantes de uma universidade pública do Estado de São Paulo. Os resultados obtidos nestes estudos sugerem, como sendo as principais razões para a doação: desejo de continuar a vida do outro; reaproveitamento dos órgãos; dar qualidade de vida aos que necessitam de um transplante; inutilidade do corpo após a morte. Quanto à não doação, as principais razões foram: crítica à lei dos transplantes; crítica ao sistema de saúde brasileiro; razões bioéticas, tais como receio de morte premeditada e contrabando de órgãos. Nestes estudos não foi encontrada relação significativa entre religião e doação de órgãos, mas foi encontrada entre o medo da morte e a não doação.

  8. Single shot DoA estimation for large-array base station systems in multi-user environments

    NARCIS (Netherlands)

    Bressner, T.A.H.; Johannsen, U.; Smolders, A.B.

    2017-01-01

    The next generation of wireless communications has to deal with the demand for higher data rates and the increase of subscribers. A feasible approach to cope with these challenges is to utilize millimeter waves (mmWaves). To provide at these high frequencies a sufficient high signal to noise ratio

  9. Multidimensional Rank Reduction Estimator for Parametric MIMO Channel Models

    Directory of Open Access Journals (Sweden)

    Marius Pesavento

    2004-08-01

    Full Text Available A novel algebraic method for the simultaneous estimation of MIMO channel parameters from channel sounder measurements is developed. We consider a parametric multipath propagation model with P discrete paths where each path is characterized by its complex path gain, its directions of arrival and departure, time delay, and Doppler shift. This problem is treated as a special case of the multidimensional harmonic retrieval problem. While the well-known ESPRIT-type algorithms exploit shift-invariance between specific partitions of the signal matrix, the rank reduction estimator (RARE algorithm exploits their internal Vandermonde structure. A multidimensional extension of the RARE algorithm is developed, analyzed, and applied to measurement data recorded with the RUSK vector channel sounder in the 2 GHz band.

  10. Performance Analysis of the Decentralized Eigendecomposition and ESPRIT Algorithm

    Science.gov (United States)

    Suleiman, Wassim; Pesavento, Marius; Zoubir, Abdelhak M.

    2016-05-01

    In this paper, we consider performance analysis of the decentralized power method for the eigendecomposition of the sample covariance matrix based on the averaging consensus protocol. An analytical expression of the second order statistics of the eigenvectors obtained from the decentralized power method which is required for computing the mean square error (MSE) of subspace-based estimators is presented. We show that the decentralized power method is not an asymptotically consistent estimator of the eigenvectors of the true measurement covariance matrix unless the averaging consensus protocol is carried out over an infinitely large number of iterations. Moreover, we introduce the decentralized ESPRIT algorithm which yields fully decentralized direction-of-arrival (DOA) estimates. Based on the performance analysis of the decentralized power method, we derive an analytical expression of the MSE of DOA estimators using the decentralized ESPRIT algorithm. The validity of our asymptotic results is demonstrated by simulations.

  11. Mixed Far-Field and Near-Field Source Localization Algorithm via Sparse Subarrays

    Directory of Open Access Journals (Sweden)

    Jiaqi Song

    2018-01-01

    Full Text Available Based on a dual-size shift invariance sparse linear array, this paper presents a novel algorithm for the localization of mixed far-field and near-field sources. First, by constructing a cumulant matrix with only direction-of-arrival (DOA information, the proposed algorithm decouples the DOA estimation from the range estimation. The cumulant-domain quarter-wavelength invariance yields unambiguous estimates of DOAs, which are then used as coarse references to disambiguate the phase ambiguities in fine estimates induced from the larger spatial invariance. Then, based on the estimated DOAs, another cumulant matrix is derived and decoupled to generate unambiguous and cyclically ambiguous estimates of range parameter. According to the coarse range estimation, the types of sources can be identified and the unambiguous fine range estimates of NF sources are obtained after disambiguation. Compared with some existing algorithms, the proposed algorithm enjoys extended array aperture and higher estimation accuracy. Simulation results are given to validate the performance of the proposed algorithm.

  12. Longpath DOAS observations of surface BrO at Summit, Greenland

    Directory of Open Access Journals (Sweden)

    J. Stutz

    2011-09-01

    Full Text Available Reactive halogens, and in particular bromine oxide (BrO, have frequently been observed in regions with large halide reservoirs, for example during bromine catalyzed coastal polar ozone depletion events. Much less is known about the presence and impact of reactive halogens in areas without obvious halide reservoirs, such as the polar ice sheets or continental snow.

    We report the first LP-DOAS measurements of BrO at Summit research station in the center of the Greenland ice sheet at an altitude of 3200 m. BrO mixing ratios in May 2007 and June 2008 were typically between 1–3 pmol mol−1, with maxima of up to 5 pmol mol−1. These measurements unequivocally show that halogen chemistry is occurring in the remote Arctic, far from known bromine reservoirs, such as the ocean. During periods when FLEXPART retroplumes show that airmasses resided on the Greenland ice sheet for 3 or more days, BrO exhibits a clear diurnal variation, with peak mixing ratios of up to 3 pmol mol−1 in the morning and at night. The diurnal cycle of BrO can be explained by a changing boundary layer height combined with photochemical formation of reactive bromine driven by solar radiation at the snow surface. The shallow stable boundary layer in the morning and night leads to an accumulation of BrO at the surface, leading to elevated BrO despite the expected smaller release from the snowpack during these times of low solar radiation. During the day when photolytic formation of reactive bromine is expected to be highest, efficient mixing into a deeper neutral boundary layer leads to lower BrO mixing ratios than during mornings and nights.

    The extended period of contact with the Greenland snowpack combined with the diurnal profile of BrO, modulated by boundary layer height, suggests that photochemistry in the snow is a significant source of BrO measured at Summit during the 2008 experiment. In addition, a rapid transport event

  13. Doação de alimentos: fetiche ou política de segurança alimentar

    OpenAIRE

    Gambardella, Alice Dianezi

    2005-01-01

    A Doação de Alimentos permanece como uma das atividades da Política de Segurança Alimentar. Tem sido ela um fetiche ou efetivamente um mecanismo constitutivo dessa política? Para examinar esta questão, foi elaborado estudo do desempenho do Banco de Alimentos do Município de São Paulo, no período de 2004. As dimensões e o alcance desta iniciativa de combate ao desperdício de alimentos serviram de base para a análise da atuação governamental sobre este tipo de ação e demais me...

  14. Fatores associados à efetividade da doação de órgãos e tecidos para transplantes

    OpenAIRE

    Freire, Izaura Luzia Silverio

    2013-01-01

    O transplante de órgãos e tecidos apresenta-se como importante opção terapêutica, tanto do ponto de vista médico, quanto social ou econômico. Assim, a identificação das variáveis que podem interferir na efetividade da doação de órgãos e tecidos para transplante precisa ser investigada de maneira adequada, pois se está diante de crescente índice de doenças crônicas e degenerativas na população, que faz com que a lista de espera para transplante aumente desproporcionalmente e os pacientes chega...

  15. Comparison of Aromatic Hydrocarbon Measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

    International Nuclear Information System (INIS)

    Jobson, Bertram T.; Volkamer, Rainer M.; Velasco, E.; Allwine, Gene; Westberg, Halvor H.; Lamb, Brian K.; Alexander, M.L.; Berkowitz, Carl M.; Molina, Luisa T.

    2010-01-01

    A comparison of aromatic hydrocarbon measurements is reported for the CENICA upersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003). Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS), long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS), and Gas Chromatography-Flame Ionization analysis (GC-FID) of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6), and were in reasonable agreement for toluene, C 2 -alkylbenzenes and C3-alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430m distance), and the point measurements collected at 37-m sampling height were best for benzene (r=0.61), and reasonably good for toluene, C2-alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5). There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the PTR-MS ethylbenzene interference. Mixing ratios easured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C2-alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients - horizontal, vertical, or both - in toluene mixing ratios were significant, and up to a factor of 2 despite the fact that all measurements were conducted above

  16. Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration

    Directory of Open Access Journals (Sweden)

    H. Fuchs

    2012-07-01

    Full Text Available During recent field campaigns, hydroxyl radical (OH concentrations that were measured by laser-induced fluorescence (LIF were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, in order to investigate the photochemical degradation of isoprene, methyl-vinyl ketone (MVK, methacrolein (MACR and aromatic compounds by OH. Conditions were similar to those experienced during the PRIDE-PRD2006 campaign in the Pearl River Delta (PRD, China, in 2006, where a large difference between OH measurements and model predictions was found. During experiments in SAPHIR, OH was simultaneously detected by two independent instruments: LIF and differential optical absorption spectroscopy (DOAS. Because DOAS is an inherently calibration-free technique, DOAS measurements are regarded as a reference standard. The comparison of the two techniques was used to investigate potential artifacts in the LIF measurements for PRD-like conditions of OH reactivities of 10 to 30 s−1 and NO mixing ratios of 0.1 to 0.3 ppbv. The analysis of twenty experiment days shows good agreement. The linear regression of the combined data set (averaged to the DOAS time resolution, 2495 data points yields a slope of 1.02 ± 0.01 with an intercept of (0.10 ± 0.03 × 106 cm−3 and a linear correlation coefficient of R2 = 0.86. This indicates that the sensitivity of the LIF instrument is well-defined by its calibration procedure. No hints for artifacts are observed for isoprene, MACR, and different aromatic compounds. LIF measurements were approximately 30–40% (median larger than those by DOAS after MVK (20 ppbv and

  17. Computationally efficient near-field source localization using third-order moments

    Science.gov (United States)

    Chen, Jian; Liu, Guohong; Sun, Xiaoying

    2014-12-01

    In this paper, a third-order moment-based estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm is proposed for passive localization of near-field sources. By properly choosing sensor outputs of the symmetric uniform linear array, two special third-order moment matrices are constructed, in which the steering matrix is the function of electric angle γ, while the rotational factor is the function of electric angles γ and ϕ. With the singular value decomposition (SVD) operation, all direction-of-arrivals (DOAs) are estimated from a polynomial rooting version. After substituting the DOA information into the steering matrix, the rotational factor is determined via the total least squares (TLS) version, and the related range estimations are performed. Compared with the high-order ESPRIT method, the proposed algorithm requires a lower computational burden, and it avoids the parameter-match procedure. Computer simulations are carried out to demonstrate the performance of the proposed algorithm.

  18. Maximum likelihood approach to “informed” Sound Source Localization for Hearing Aid applications

    DEFF Research Database (Denmark)

    Farmani, Mojtaba; Pedersen, Michael Syskind; Tan, Zheng-Hua

    2015-01-01

    Most state-of-the-art Sound Source Localization (SSL) algorithms have been proposed for applications which are "uninformed'' about the target sound content; however, utilizing a wireless microphone worn by a target talker, enables recent Hearing Aid Systems (HASs) to access to an almost noise......-free sound signal of the target talker at the HAS via the wireless connection. Therefore, in this paper, we propose a maximum likelihood (ML) approach, which we call MLSSL, to estimate the Direction of Arrival (DoA) of the target signal given access to the target signal content. Compared with other "informed...

  19. Transmit/Receive Spatial Smoothing with Improved Effective Array Aperture for Angle and Mutual Coupling Estimation in Bistatic MIMO Radar

    Directory of Open Access Journals (Sweden)

    Haomiao Liu

    2016-01-01

    Full Text Available We proposed a transmit/receive spatial smoothing with improved effective aperture approach for angle and mutual coupling estimation in bistatic MIMO radar. Firstly, the noise in each channel is restrained, by exploiting its independency, in both the spatial domain and temporal domain. Then the augmented transmit and receive spatial smoothing matrices with improved effective aperture are obtained, by exploiting the Vandermonde structure of steering vector with uniform linear array. The DOD and DOA can be estimated by utilizing the unitary ESPRIT algorithm. Finally, the mutual coupling coefficients of both the transmitter and the receiver can be figured out with the estimated angles of DOD and DOA. Numerical examples are presented to verify the effectiveness of the proposed method.

  20. Retrievals of formaldehyde from ground-based FTIR and MAX-DOAS observations at the Jungfraujoch station and comparisons with GEOS-Chem and IMAGES model simulations

    Directory of Open Access Journals (Sweden)

    B. Franco

    2015-04-01

    Full Text Available As an ubiquitous product of the oxidation of many volatile organic compounds (VOCs, formaldehyde (HCHO plays a key role as a short-lived and reactive intermediate in the atmospheric photo-oxidation pathways leading to the formation of tropospheric ozone and secondary organic aerosols. In this study, HCHO profiles have been successfully retrieved from ground-based Fourier transform infrared (FTIR solar spectra and UV-visible Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS scans recorded during the July 2010–December 2012 time period at the Jungfraujoch station (Swiss Alps, 46.5° N, 8.0° E, 3580 m a.s.l.. Analysis of the retrieved products has revealed different vertical sensitivity between both remote sensing techniques. Furthermore, HCHO amounts simulated by two state-of-the-art chemical transport models (CTMs, GEOS-Chem and IMAGES v2, have been compared to FTIR total columns and MAX-DOAS 3.6–8 km partial columns, accounting for the respective vertical resolution of each ground-based instrument. Using the CTM outputs as the intermediate, FTIR and MAX-DOAS retrievals have shown consistent seasonal modulations of HCHO throughout the investigated period, characterized by summertime maximum and wintertime minimum. Such comparisons have also highlighted that FTIR and MAX-DOAS provide complementary products for the HCHO retrieval above the Jungfraujoch station. Finally, tests have revealed that the updated IR parameters from the HITRAN 2012 database have a cumulative effect and significantly decrease the retrieved HCHO columns with respect to the use of the HITRAN 2008 compilation.

  1. TSaT-MUSIC: a novel algorithm for rapid and accurate ultrasonic 3D localization

    Science.gov (United States)

    Mizutani, Kyohei; Ito, Toshio; Sugimoto, Masanori; Hashizume, Hiromichi

    2011-12-01

    We describe a fast and accurate indoor localization technique using the multiple signal classification (MUSIC) algorithm. The MUSIC algorithm is known as a high-resolution method for estimating directions of arrival (DOAs) or propagation delays. A critical problem in using the MUSIC algorithm for localization is its computational complexity. Therefore, we devised a novel algorithm called Time Space additional Temporal-MUSIC, which can rapidly and simultaneously identify DOAs and delays of mul-ticarrier ultrasonic waves from transmitters. Computer simulations have proved that the computation time of the proposed algorithm is almost constant in spite of increasing numbers of incoming waves and is faster than that of existing methods based on the MUSIC algorithm. The robustness of the proposed algorithm is discussed through simulations. Experiments in real environments showed that the standard deviation of position estimations in 3D space is less than 10 mm, which is satisfactory for indoor localization.

  2. Participação da comunidade no 7° dia de doação de sangue na Universidade do Estado do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Cibele Rodrigues Paes Leme

    1991-12-01

    Full Text Available Esta pesquisa mostra o perfil social dos doadores que participaram do 7° Dia de Doação de Sangue na UERJ e tem como objetivo a análise dos fatores que incentivaram a comunidade a doar sangue e a avaliação da divulgação de tal evento entre os doadores. Utilizou-se o método descritivo e a técnica de investigação social através de um questionário composto de 14 perguntas, sendo sete objetivas e sete subjetivas, que foi respondido pelos doadores no ato da doação de sangue. A amostra foi constituída de 129 doadores. A campanha de doação de sangue foi realizada no "Campus" da Universidade do Estado do Rio de Janeiro, no dia 24 de abril de 1991, das 08 às 17 horas. Como resultado pode-se observar uma amostra composta em sua maioria de adultos jovens, do sexo masculino, de cor branca, solteiros, estudantes do 3° Grau, tendo a solidariedade como a principal razão para doar sangue. Recomenda-se aos organizadores do evento maior divulgação das futuras campanhas, visando com isso uma participação efetivamente significativa da comunidade como um todo.

  3. Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

    Directory of Open Access Journals (Sweden)

    P. Zieger

    2011-03-01

    Full Text Available In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%. Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties – especially the aerosol light scattering – are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient σsp(λ was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,λ is the key parameter to describe the effect of RH on σsp(λ and is defined as σsp(RH,λ measured at a certain RH divided by the dry σsp(dry,λ. The measurement of f(RH,λ together with the dry absorption measurement (assumed not to change with RH allows the determination of the actual extinction coefficient σep(RH,λ at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition a simple parameterization of f(RH,λ could not be established. If f(RH,λ needs to be predicted, the chemical composition and size distribution need to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy instruments were used to retrieve vertical profiles of σep(λ. The values of the lowest layer were compared to the in-situ values after conversion of the latter ones to ambient

  4. SCIAMACHY WFM-DOAS XCO2: comparison with CarbonTracker XCO2 focusing on aerosols and thin clouds

    Directory of Open Access Journals (Sweden)

    J. P. Burrows

    2012-08-01

    Full Text Available Carbon dioxide (CO2 is the most important greenhouse gas whose atmospheric loading has been significantly increased by anthropogenic activity leading to global warming. Accurate measurements and models are needed in order to reliably predict our future climate. This, however, has challenging requirements. Errors in measurements and models need to be identified and minimised. In this context, we present a comparison between satellite-derived column-averaged dry air mole fractions of CO2, denoted XCO2, retrieved from SCIAMACHY/ENVISAT using the WFM-DOAS (weighting function modified differential optical absorption spectroscopy algorithm, and output from NOAA's global CO2 modelling and assimilation system CarbonTracker. We investigate to what extent differences between these two data sets are influenced by systematic retrieval errors due to aerosols and unaccounted clouds. We analyse seven years of SCIAMACHY WFM-DOAS version 2.1 retrievals (WFMDv2.1 using CarbonTracker version 2010. We investigate to what extent the difference between SCIAMACHY and CarbonTracker XCO2 are temporally and spatially correlated with global aerosol and cloud data sets. For this purpose, we use a global aerosol data set generated within the European GEMS project, which is based on assimilated MODIS satellite data. For clouds, we use a data set derived from CALIOP/CALIPSO. We find significant correlations of the SCIAMACHY minus CarbonTracker XCO2 difference with thin clouds over the Southern Hemisphere. The maximum temporal correlation we find for Darwin, Australia (r2 = 54%. Large temporal correlations with thin clouds are also observed over other regions of the Southern Hemisphere (e.g. 43% for South America and 31% for South Africa. Over the Northern Hemisphere the temporal correlations are typically much lower. An exception is India, where large temporal correlations with clouds and aerosols have also been found. For all other regions the temporal correlations with

  5. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Directory of Open Access Journals (Sweden)

    R. Thalman

    2010-12-01

    Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO2, glyoxal (CHOCHO, methyl glyoxal (CH3COCHO, iodine oxide (IO, water vapour (H2O and oxygen dimers (O4. We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7 × 10−7cm−1. Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype

  6. THE IMPROVEMENT OF FAMILY COPING IN TAKING CARE OF PATIENT MENTAL DISORDER WITH SPIRITUAL THERAPY; DIRECTION, OBEDIENCE AND ACCEPTANCE (DOA

    Directory of Open Access Journals (Sweden)

    Ah. Yusuf

    2017-04-01

    Full Text Available Introduction: Mental disorder remains a stigma in society, even until now. A family who have a member with mental disorder, will experience continues objective and subjective burden, experience serious stress for a lifetime, which may cause ineffective coping. Method: Design used in this study was experimental (pre post test control group design. The population was every family of patient with mental disorder in Menur Mental Hospital along the year of 2010, has been taking care there twice, in minimum, lived in Surabaya. The samples were chosen by allocation simple random. Samples were 13 persons in each treatment and control group. The intervention was given in 60–120 minute in 8 times meeting with average interval about 1 week. Data analysis was done using paired t-test and independent t-test. Result: Results in this study showed that there was significant change in total of family coping (p = 0.040, maintaining family integration, cooperation and an optimistic definition of the stuation (p = 0.009, maintaining social support, self esteem, and psychological stability (p = 0.230, understanding the medical situations through communication with other parents and concultation with medical staff (p = 0.025. Discussion: The provision of family therapy with spiritual approach (DOA can increase family coping in taking care of patient with mental disorder.

  7. Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS in the red spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-01-01

    Full Text Available A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm reflectance structures (i.e. "fingerprint" structures of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS, which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms. The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

  8. NO2 DOAS measurements from ground and space: comparison of ground based measurements and OMI data in Mexico City

    Science.gov (United States)

    Rivera, C.; Stremme, W.; Grutter, M.

    2012-04-01

    The combination of satellite data and ground based measurements can provide valuable information about atmospheric chemistry and air quality. In this work we present a comparison between measured ground based NO2 differential columns at the Universidad Nacional Autónoma de México (UNAM) in Mexico City, using the Differential Optical Absorption Spectroscopy (DOAS) technique and NO2 total columns measured by the Ozone Monitoring Instrument (OMI) onboard the Aura satellite using the same measurement technique. From these data, distribution maps of average NO2 above the Mexico basin were constructed and hot spots inside the city could be identified. In addition, a clear footprint was detected from the Tula industrial area, ~50 km northwest of Mexico City, where a refinery, a power plant and other industries are located. A less defined footprint was identified in the Cuernavaca basin, South of Mexico City, and the nearby cities of Toluca and Puebla do not present strong enhancements in the NO2 total columns. With this study we expect to cross-validate space and ground measurements and provide useful information for future studies.

  9. Multi-Target Angle Tracking Algorithm for Bistatic Multiple-Input Multiple-Output (MIMO Radar Based on the Elements of the Covariance Matrix

    Directory of Open Access Journals (Sweden)

    Zhengyan Zhang

    2018-03-01

    Full Text Available In this paper, we consider the problem of tracking the direction of arrivals (DOA and the direction of departure (DOD of multiple targets for bistatic multiple-input multiple-output (MIMO radar. A high-precision tracking algorithm for target angle is proposed. First, the linear relationship between the covariance matrix difference and the angle difference of the adjacent moment was obtained through three approximate relations. Then, the proposed algorithm obtained the relationship between the elements in the covariance matrix difference. On this basis, the performance of the algorithm was improved by averaging the covariance matrix element. Finally, the least square method was used to estimate the DOD and DOA. The algorithm realized the automatic correlation of the angle and provided better performance when compared with the adaptive asymmetric joint diagonalization (AAJD algorithm. The simulation results demonstrated the effectiveness of the proposed algorithm. The algorithm provides the technical support for the practical application of MIMO radar.

  10. Multi-Target Angle Tracking Algorithm for Bistatic Multiple-Input Multiple-Output (MIMO) Radar Based on the Elements of the Covariance Matrix.

    Science.gov (United States)

    Zhang, Zhengyan; Zhang, Jianyun; Zhou, Qingsong; Li, Xiaobo

    2018-03-07

    In this paper, we consider the problem of tracking the direction of arrivals (DOA) and the direction of departure (DOD) of multiple targets for bistatic multiple-input multiple-output (MIMO) radar. A high-precision tracking algorithm for target angle is proposed. First, the linear relationship between the covariance matrix difference and the angle difference of the adjacent moment was obtained through three approximate relations. Then, the proposed algorithm obtained the relationship between the elements in the covariance matrix difference. On this basis, the performance of the algorithm was improved by averaging the covariance matrix element. Finally, the least square method was used to estimate the DOD and DOA. The algorithm realized the automatic correlation of the angle and provided better performance when compared with the adaptive asymmetric joint diagonalization (AAJD) algorithm. The simulation results demonstrated the effectiveness of the proposed algorithm. The algorithm provides the technical support for the practical application of MIMO radar.

  11. Toward Quantitative Estimation of the Effect of Aerosol Particles in the Global Climate Model and Cloud Resolving Model

    Science.gov (United States)

    Eskes, H.; Boersma, F.; Dirksen, R.; van der A, R.; Veefkind, P.; Levelt, P.; Brinksma, E.; van Roozendael, M.; de Smedt, I.; Gleason, J.

    2005-05-01

    Based on measurements of GOME on ESA ERS-2, SCIAMACHY on ESA-ENVISAT, and Ozone Monitoring Instrument (OMI) on the NASA EOS-Aura satellite there is now a unique 11-year dataset of global tropospheric nitrogen dioxide measurements from space. The retrieval approach consists of two steps. The first step is an application of the DOAS (Differential Optical Absorption Spectroscopy) approach which delivers the total absorption optical thickness along the light path (the slant column). For GOME and SCIAMACHY this is based on the DOAS implementation developed by BIRA/IASB. For OMI the DOAS implementation was developed in a collaboration between KNMI and NASA. The second retrieval step, developed at KNMI, estimates the tropospheric vertical column of NO2 based on the slant column, cloud fraction and cloud top height retrieval, stratospheric column estimates derived from a data assimilation approach and vertical profile estimates from space-time collocated profiles from the TM chemistry-transport model. The second step was applied with only minor modifications to all three instruments to generate a uniform 11-year data set. In our talk we will address the following topics: - A short summary of the retrieval approach and results - Comparisons with other retrievals - Comparisons with global and regional-scale models - OMI-SCIAMACHY and SCIAMACHY-GOME comparisons - Validation with independent measurements - Trend studies of NO2 for the past 11 years

  12. Comparison of aromatic hydrocarbon measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

    Directory of Open Access Journals (Sweden)

    B. T. Jobson

    2010-02-01

    Full Text Available A comparison of aromatic hydrocarbon measurements is reported for the CENICA supersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003. Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS, long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS, and Gas Chromatography-Flame Ionization analysis (GC-FID of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6, and were in reasonable agreement for toluene, C2-alkylbenzenes and C3-alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430 m distance, and the point measurements collected at 37-m sampling height were best for benzene (r=0.61, and reasonably good for toluene, C2-alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5. There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the PTR-MS ethylbenzene interference. Mixing ratios measured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C2-alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients – horizontal, vertical, or both – in toluene mixing ratios were significant, and

  13. Estimations of pollution emissions by the Moscow megapolis basing on in-situ measurements and optical remote sensing

    Science.gov (United States)

    Elansky, N.; Postylyakov, O.; Verevkin, Y.; Volobuev, L.; Ponomarev, N.

    2017-11-01

    By the present a large amount of data has been accumulated on direct measurements of the pollution and thermodynamic state of the atmosphere in the Moscow region, which was obtained at stations of Roshydromet, Mosecomonitoring, A.M.Obukhov Institute of Atmospheric Physics (OIAP), M.V. Lomonosov Moscow State University, NPO Typhoon, what allows estimating pollution emissions based on measurements and correcting existing emission inventories, which are evaluated mainly on indirect data connected with population density, fuel consumption, etc. Within the framework of the project, the whole volume of data on the concentration of ground contaminants CO, NOx, SO2, CH4, obtained at regularly operated Moscow Ecological Monitoring stations and at OIAP stations from 2005 to 2014, was systematized. Observation data on pollution concentrations are supplemented by measurements of their integral content in the atmospheric boundary layer, obtained by differential spectroscopy methods (MAX DOAS, ZDOAS) at stationary stations and by passing Moscow with DOAS-equipped car. The paper present preliminary estimates of pollution emissions in the Moscow region, obtained on the basis of the collected array of experimental data. The estimations of pollutant emissions from Moscow were obtained experimentally in a few ways: (1) on the basis of network observations of surface concentrations, (2) on the basis of measurements in the atmospheric layer 0-348 m at Ostankino TV tower, (3) on the basis of the integral pollutant (NO2) content in ABL obtained by DOAS technique from stationary stations, and (4) using a car with DOAS equipment traveling over the closed route around Moscow (for NO2). All experimental approaches yielded close values of pollution emissions for Moscow. Trends in emissions of CO, NOx, and CH4 are negative, and the trend of SO2 emission is positive from 2005 to 2014.

  14. Airborne multi-axis DOAS measurements of tropospheric SO2 plumes in the Po-valley, Italy

    Directory of Open Access Journals (Sweden)

    P. Wang

    2006-01-01

    Full Text Available During the second FORMAT (FORMaldehyde as A Tracer of oxidation in the troposphere campaign in 2003 the airborne multi-axis DOAS instrument (AMAXDOAS performed scattered-light spectroscopic measurements of SO2 over the city of Mantova and the power plant Porto Tolle, both situated in the Po-valley, Northern Italy. The SO2 vertical columns and emission flux were derived from two days of measurements, 26 and 27 September 2003. The SO2 emission flux from the power plant Porto Tolle was calculated to 1.93×1025 molec s-1 on 26 September and in good agreement with official emission data, which quote 2.25×1025 molec s-1. On 27 September the measured flux was much lower (3.77×1024 molec s-1 if ECMWF wind data are used, but of comparable magnitude (2.4×1025 molec s-1 if the aircraft on-board wind measurements are utilised. Official emission data was 2.07×1025 molec s-1 indicating only a small change from the previous day. Over the city of Mantova, the observed SO2 vertical columns were 1.1×1016 molec cm-2 and 1.9×1016 molec cm-2 on 26 and 27 September, respectively. This is in good agreement with ground-based measurements of 5.9 ppbv and 10.0 ppbv which correspond to 1.2×1016 molec cm-2 and 2.2×1016 molec cm-2 if a well mixed boundary layer of 500m altitude is assumed.

  15. Genetic and Clinical Analyses of DOA and LHON in 304 Chinese Patients with Suspected Childhood-Onset Hereditary Optic Neuropathy.

    Directory of Open Access Journals (Sweden)

    Yadi Li

    Full Text Available Leber hereditary optic neuropathy (LHON and dominant optic atrophy (DOA, the most common forms of hereditary optic neuropathy, are easily confused, and it is difficult to distinguish one from the other in the clinic, especially in young children. The present study was designed to survey the mutation spectrum of common pathogenic genes (OPA1, OPA3 and mtDNA genes and to analyze the genotype-phenotype characteristics of Chinese patients with suspected childhood-onset hereditary optic neuropathy. Genomic DNA and clinical data were collected from 304 unrelated Chinese probands with suspected hereditary optic neuropathy with an age of onset below 14 years. Sanger sequencing was used to screen variants in the coding and adjacent regions of OPA1, OPA3 and the three primary LHON-related mutation sites in mitochondrial DNA (mtDNA (m.3460G>A, m.11778G>A and m.14484T>C. All patients underwent a complete ophthalmic examination and were compared with age-matched controls. We identified 89/304 (29.3% primary mtDNA mutations related to LHON in 304 probands, including 76 mutations at m.11778 (76/89, 85.4% of all mtDNA mutations, four at m.3460 (4/89, 4.5% and nine at m.14484 (9/89, 10.1%. This result was similar to the mutation frequency among Chinese patients with LHON of any age. Screening of OPA1 revealed 23 pathogenic variants, including 11 novel and 12 known pathogenic mutations. This study expanded the OPA1 mutation spectrum, and our results showed that OPA1 mutation is another common cause of childhood-onset hereditary optic neuropathy in Chinese pediatric patients, especially those with disease onset during preschool age.

  16. Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

    Directory of Open Access Journals (Sweden)

    A. K. Thorpe

    2017-10-01

    Full Text Available At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

  17. Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

    Science.gov (United States)

    Thorpe, Andrew K.; Frankenberg, Christian; Thompson, David R.; Duren, Riley M.; Aubrey, Andrew D.; Bue, Brian D.; Green, Robert O.; Gerilowski, Konstantin; Krings, Thomas; Borchardt, Jakob; Kort, Eric A.; Sweeney, Colm; Conley, Stephen; Roberts, Dar A.; Dennison, Philip E.

    2017-10-01

    At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

  18. Pesquisa-ação com alunos do curso de graduação em enfermagem sobre o processo de doação de órgãos

    OpenAIRE

    Elton Carlos de Almeida

    2015-01-01

    Esta pesquisa centra-se na formação profissional voltada para o processo de doação/transplante de órgãos humanos, visto tratar-se de assuntos complexos que demandam, entre outros aspectos, o preparo profissional adequado para atuação oportuna. Assim, neste estudo, objetivou-se analisar a formação, o preparo e o enfrentamento dos problemas relativos ao processo de doação de órgãos, identificando esses elementos com os graduandos em Enfermagem, de uma instituição pública, possibilitando...

  19. ESPRIT-like algorithm for computational-efficient angle estimation in bistatic multiple-input multiple-output radar

    Science.gov (United States)

    Gong, Jian; Lou, Shuntian; Guo, Yiduo

    2016-04-01

    An estimation of signal parameters via a rotational invariance techniques-like (ESPRIT-like) algorithm is proposed to estimate the direction of arrival and direction of departure for bistatic multiple-input multiple-output (MIMO) radar. The properties of a noncircular signal and Euler's formula are first exploited to establish a real-valued bistatic MIMO radar array data, which is composed of sine and cosine data. Then the receiving/transmitting selective matrices are constructed to obtain the receiving/transmitting rotational invariance factors. Since the rotational invariance factor is a cosine function, symmetrical mirror angle ambiguity may occur. Finally, a maximum likelihood function is used to avoid the estimation ambiguities. Compared with the existing ESPRIT, the proposed algorithm can save about 75% of computational load owing to the real-valued ESPRIT algorithm. Simulation results confirm the effectiveness of the ESPRIT-like algorithm.

  20. Assimilative model for ionospheric dynamics employing delay, Doppler, and direction of arrival measurements from multiple HF channels

    Science.gov (United States)

    Fridman, Sergey V.; Nickisch, L. J.; Hausman, Mark; Zunich, George

    2016-03-01

    We describe the development of new HF data assimilation capabilities for our ionospheric inversion algorithm called GPSII (GPS Ionospheric Inversion). Previously existing capabilities of this algorithm included assimilation of GPS total electron content data as well as assimilation of backscatter ionograms. In the present effort we concentrated on developing assimilation tools for data related to HF propagation channels. Measurements of propagation delay, angle of arrival, and the ionosphere-induced Doppler from any number of known propagation links can now be utilized by GPSII. The resulting ionospheric model is consistent with all assimilated measurements. This means that ray tracing simulations of the assimilated propagation links are guaranteed to be in agreement with measured data within the errors of measurement. The key theoretical element for assimilating HF data is the raypath response operator (RPRO) which describes response of raypath parameters to infinitesimal variations of electron density in the ionosphere. We construct the RPRO out of the fundamental solution of linearized ray tracing equations for a dynamic magnetoactive plasma. We demonstrate performance and internal consistency of the algorithm using propagation delay data from multiple oblique ionograms (courtesy of Defence Science and Technology Organisation, Australia) as well as with time series of near-vertical incidence sky wave data (courtesy of the Intelligence Advanced Research Projects Activity HFGeo Program Government team). In all cases GPSII produces electron density distributions which are smooth in space and in time. We simulate the assimilated propagation links by performing ray tracing through GPSII-produced ionosphere and observe that simulated data are indeed in agreement with assimilated measurements.

  1. Doação de órgãos: meu corpo, minha sociedade Organ donation: my body, my society

    Directory of Open Access Journals (Sweden)

    Pedro Fernando Bendassolli

    1998-01-01

    Full Text Available A doação de órgãos é um problema de relevância social e científica, pois envolve as formas como a vida é perpetuada através do corpo de outra pessoa, especificamente por meio de seus órgãos. Quais são os fatores de resistência e de facilitação à doação de órgãos? Este artigo propõe um fator de resistência e um de facilitação. O primeiro, o narcisismo pelo próprio corpo; o segundo, o desejo de perpetuar-se a si mesmo e a vida.Organ donation is a problem of social and scientific relevance because it involves the ways through which life is perpetuated across another person’s body, specifically by its organs. What are resistance and facilitation factors to organ donation? This article proposes one factor of resistance and one of facilitation. The first, the narcissism of the own body; the second, the desire of perpetuate oneself and life.

  2. Integrating qualified nurses and non-nurses in midwifery education: the two-year experience of an ACNM DOA Accredited Program.

    Science.gov (United States)

    Fullerton, J T; Shah, M A; Schechter, S; Muller, J H

    2000-01-01

    In 1996, the Division of Accreditation (DOA) of the American College of Nurse-Midwives (ACNM) preaccredited the first direct entry program of midwifery education for candidates who already possess undergraduate degrees in non-nursing disciplines. Inaugurated through the partnership of the State University of New York Health Science Center at Brooklyn and the North Central Bronx Hospital, this 1-year, postbaccalaureate, certificate program of studies graduated two integrated classes of 22 registered nurse (RN) and nine direct entry (DE) students between 1997 and 1998. This article presents the experience of the first 2 years of this innovative program, focusing on the profiles of the DE students, their achievements, and their experiences entering the workforce. All of the data comparing nurse and non-nurse student progress through the program of studies strongly support the conclusion that, within an ACNM DOA preaccredited/accredited midwifery education program, DE students can achieve standards of academic excellence and clinical competency that are at least equivalent to those demonstrated by their RN peers.

  3. Revisão integrativa: indicadores de resultado processo de doação de órgãos e transplantes

    Directory of Open Access Journals (Sweden)

    Agenor Spallini Ferraz

    2013-09-01

    Full Text Available OBJETIVO: Identificar por meio da revisão integrativa os principais indicadores de resultado do processo de doação de órgãos e transplantes utilizados e transplantes no Brasil e no mundo. A revisão integrativa da literatura foi realizada nas bases de dados bibliográficas MedLine/PubMed e LILACS e sites governamentais e não governamentais no período de 1995 e 2011. Os descritores/palavras chaves utilizados foram doação de órgãos, transplante de órgãos e resultados em saúde, sendo selecionados 26 artigos e nove sites. A classificação do nível de evidência dos artigos variou de um a seis. RESULTADOS: Nível de evidência dos artigos na sua maioria 66,6% foi quatro (12:18 PubMed todos os artigos da base LILACS (8. Os indicadores apresentados nos artigos se propõem a avaliar, mensurar e controlar dados relacionados ao perfil do doador, condições clínicas e hospitalares, tempo de isquemia e tamanho do órgão, procedimento cirúrgico e as complicações advindas do transplante.

  4. Conhecendo os Meandros da Doação de Sangue: Implicações para a Atuação do Enfermeiro na Hemoterapia

    Directory of Open Access Journals (Sweden)

    Gilce Erbe de Miranda Silva

    2015-02-01

    Full Text Available Objetivo: o estudo tem como objetivo discutir os significados apreendidos pelos não doadores de sangue, considerando o contexto e as consequências para a atuação do enfermeiro na hemoterapia. Método: optou-se pela abordagem qualitativa, com o referencial teórico do Interacionismo Simbólico e o método daGrounded Theory. A produção de dados foi realizada por entrevista intensiva com sujeitos de três grupos amostrais de um Hospital Universitário da Cidade do Rio de Janeiro. Resultados: o fenômeno gerou duas categorias de análise: "Percebendo a questão do sangue" e "Refletindo sobre as campanhas de doação de sangue". Observou-se que o ambiente do não doador é composto pelo contato com o outro e com as informações que este possa alcançar, inclusive a mídia. Conclusão: estas foram as principais bases para o conhecimento sobre a doação de sangue, que fazem nexo com as suas crenças, cultura e valores. Portanto, todos estes aspectos devem ser considerados pelo enfermeiro que atua na captação de doadores.

  5. Wearable Sensor Localization Considering Mixed Distributed Sources in Health Monitoring Systems.

    Science.gov (United States)

    Wan, Liangtian; Han, Guangjie; Wang, Hao; Shu, Lei; Feng, Nanxing; Peng, Bao

    2016-03-12

    In health monitoring systems, the base station (BS) and the wearable sensors communicate with each other to construct a virtual multiple input and multiple output (VMIMO) system. In real applications, the signal that the BS received is a distributed source because of the scattering, reflection, diffraction and refraction in the propagation path. In this paper, a 2D direction-of-arrival (DOA) estimation algorithm for incoherently-distributed (ID) and coherently-distributed (CD) sources is proposed based on multiple VMIMO systems. ID and CD sources are separated through the second-order blind identification (SOBI) algorithm. The traditional estimating signal parameters via the rotational invariance technique (ESPRIT)-based algorithm is valid only for one-dimensional (1D) DOA estimation for the ID source. By constructing the signal subspace, two rotational invariant relationships are constructed. Then, we extend the ESPRIT to estimate 2D DOAs for ID sources. For DOA estimation of CD sources, two rational invariance relationships are constructed based on the application of generalized steering vectors (GSVs). Then, the ESPRIT-based algorithm is used for estimating the eigenvalues of two rational invariance matrices, which contain the angular parameters. The expressions of azimuth and elevation for ID and CD sources have closed forms, which means that the spectrum peak searching is avoided. Therefore, compared to the traditional 2D DOA estimation algorithms, the proposed algorithm imposes significantly low computational complexity. The intersecting point of two rays, which come from two different directions measured by two uniform rectangle arrays (URA), can be regarded as the location of the biosensor (wearable sensor). Three BSs adopting the smart antenna (SA) technique cooperate with each other to locate the wearable sensors using the angulation positioning method. Simulation results demonstrate the effectiveness of the proposed algorithm.

  6. Direct observation of two dimensional trace gas distributions with an airborne Imaging DOAS instrument

    Directory of Open Access Journals (Sweden)

    K.-P. Heue

    2008-11-01

    Full Text Available In many investigations of tropospheric chemistry information about the two dimensional distribution of trace gases on a small scale (e.g. tens to hundreds of metres is highly desirable. An airborne instrument based on imaging Differential Optical Absorption Spectroscopy has been built to map the two dimensional distribution of a series of relevant trace gases including NO2, HCHO, C2H2O2, H2O, O4, SO2, and BrO on a scale of 100 m.

    Here we report on the first tests of the novel aircraft instrument over the industrialised South African Highveld, where large variations in NO2 column densities in the immediate vicinity of several sources e.g. power plants or steel works, were measured. The observed patterns in the trace gas distribution are interpreted with respect to flux estimates, and it is seen that the fine resolution of the measurements allows separate sources in close proximity to one another to be distinguished.

  7. Development and application of a low-cost, portable DOAS system for stratospheric composition monitoring over the Argentinean Patagonia and Antarctic stations.

    Science.gov (United States)

    Raponi, Marcelo; Jiménez, Rodrigo; Ristori, Pablo; Wolfram, Elian; Tocho, Jorge; Quel, Eduardo

    2010-05-01

    A significant fraction of the Argentinean population is seasonally exposed to elevated UV radiation, particularly during severe stratospheric ozone destruction episodes in Antarctica. In order to provide early alert, global monitoring and to improve our understanding of these phenomena, various Argentinean and international organizations maintain stratospheric composition remote sensing sites from the southern tip of Argentina (Patagonia) to Antarctica. The understating of the ozone destruction dynamics will be significantly improved if more sites were available. For instance, the Laser and Applications Research Center, CEILAP (CITEFA-CONICET, Argentina) carries out systematic measurements of stratospheric ozone and tropospheric water vapor profiles at Rio Gallego (51° 36' S, 69° 19' W, 15 m asl) by means of LIDAR systems. Besides the active systems, the site possesses different passive instruments (GUV-541, UV-B and UV-A radiometers, SAOZ spectrometer, CIMEL sunphotometer) all of them working in synergy. The goal of this work is to present the design and development of a new compact atmospheric remote sensing system, able to determine the vertical column concentration in column (VCD) of multiple trace gases. We have developed a low-cost, portable passive DOAS system, ERO-DOAS, wich circumvents the cost limitations associated with new fixed monitoring sites. It is composed of commercial spectrophotometer (HR4000, Ocean Optics), a 400-μm core, 6-m long optic fiber, and a home-made automatic external shutter. We have developed a LabVIEW® based software for spectrometer/shutter control and data acquisition, and a MATLAB® based software for spectral data reduction. In the work we highlight the main characteristics of the system's components and we describe the visual interface implemented to controls the operation of the whole system, and the calculation algorithms to process the measured zenithal spectra, postulating the strategies implemented to solve the

  8. Generation of a rabbit single-chain fragment variable (scFv) antibody for specific detection of Bradyrhizobium sp. DOA9 in both free-living and bacteroid forms.

    Science.gov (United States)

    Vu, Nguyen Xuan; Pruksametanan, Natcha; Srila, Witsanu; Yuttavanichakul, Watcharin; Teamtisong, Kamonluck; Teaumroong, Neung; Boonkerd, Nantakorn; Tittabutr, Panlada; Yamabhai, Montarop

    2017-01-01

    A simple and reliable method for the detection of specific nitrogen-fixing bacteria in both free-living and bacteroid forms is essential for the development and application of biofertilizer. Traditionally, a polyclonal antibody generated from an immunized rabbit was used for detection. However, the disadvantages of using a polyclonal antibody include limited supply and cross-reactivity to related bacterial strains. This is the first report on the application of phage display technology for the generation of a rabbit recombinant monoclonal antibody for specific detection and monitoring of nitrogen-fixing bacteria in both free-living form and in plant nodules. Bradyrhizobium sp. DOA9, a broad host range soil bacteria, originally isolated from the root nodules of Aeschynomene americana in Thailand was used as a model in this study. A recombinant single-chain fragment variable (scFv) antibody library was constructed from the spleen of a rabbit immunized with DOA9. After three rounds of biopanning, one specific phage-displayed scFv antibody, designated bDOA9rb8, was identified. Specific binding of this antibody was confirmed by phage enzyme-linked immunosorbent assay (phage ELISA). The phage antibody could bind specifically to DOA9 in both free-living cells (pure culture) and bacteroids inside plant nodules. In addition to phage ELISA, specific and robust immunofluorescence staining of both free-living and bacteroid forms could also be observed by confocal-immunofluorescence imaging, without cross-reactivity with other tested bradyrhizobial strains. Moreover, specific binding of free scFv to DOA9 was also demonstrated by ELISA. This recombinant antibody can also be used for the study of the molecular mechanism of plant-microbe interactions in the future.

  9. Signal and array processing techniques for RFID readers

    Science.gov (United States)

    Wang, Jing; Amin, Moeness; Zhang, Yimin

    2006-05-01

    Radio Frequency Identification (RFID) has recently attracted much attention in both the technical and business communities. It has found wide applications in, for example, toll collection, supply-chain management, access control, localization tracking, real-time monitoring, and object identification. Situations may arise where the movement directions of the tagged RFID items through a portal is of interest and must be determined. Doppler estimation may prove complicated or impractical to perform by RFID readers. Several alternative approaches, including the use of an array of sensors with arbitrary geometry, can be applied. In this paper, we consider direction-of-arrival (DOA) estimation techniques for application to near-field narrowband RFID problems. Particularly, we examine the use of a pair of RFID antennas to track moving RFID tagged items through a portal. With two antennas, the near-field DOA estimation problem can be simplified to a far-field problem, yielding a simple way for identifying the direction of the tag movement, where only one parameter, the angle, needs to be considered. In this case, tracking of the moving direction of the tag simply amounts to computing the spatial cross-correlation between the data samples received at the two antennas. It is pointed out that the radiation patterns of the reader and tag antennas, particularly their phase characteristics, have a significant effect on the performance of DOA estimation. Indoor experiments are conducted in the Radar Imaging and RFID Labs at Villanova University for validating the proposed technique for target movement direction estimations.

  10. Conhecimento de estudantes de medicina sobre o processo de doação de córneas The knowledge of medical students about cornea donation

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2007-08-01

    Full Text Available OBJETIVO: Avaliar o conhecimento de estudantes de medicina sobre o processo de doação de córneas, comparando-o entre aqueles que já cursaram a disciplina de Oftalmologia com os demais. MÉTODOS: Foi aplicado um questionário a estudantes de medicina do interior de São Paulo, contendo dados como: idade, sexo, ano de graduação e 10 perguntas de múltipla escolha sobre o tema. As questões abordaram o limite de idade para doação, contra-indicações para o transplante, tempo para retirada das córneas, dentre outras. Foi comparado o conhecimento (% de acertos entre aqueles que haviam cursado a disciplina de Oftalmologia (Grupo A com os demais (Grupo B. RESULTADOS: Foram entrevistados 402 estudantes. Destes, 140 eram do grupo A e 262 do grupo B. Não houve diferença estatisticamente significante entre os dois grupos (p=0,8328. CONCLUSÃO: O conhecimento sobre o processo de doação de córneas mostrou-se insuficiente entre os alunos entrevistados, mesmo para aqueles que haviam cursado a disciplina de Oftalmologia, apontando a necessidade de aperfeiçoamento do conhecimento divulgado nas escolas médicas.PURPOSE: To compare knowledge of medical students about the cornea donation process among those who already studied Ophthalmology and the others. METHODOS: A questionnaire containing data as: age, sex, graduation year, and 10 multiple-choice questions about the subject was applied to medical students from the interior of São Paulo state, Brazil. The questions were: age for donation, contraindication for transplants, the time limit to remove the cornea, among others. The knowledge regarding cornea donation was compared between the two groups: students who already studied Ophthalmology (Group A and the others (Group B. RESULTS: The study group was composed of 402 students, of whom 140 were of group A and 262 of group B. Knowledge between the two groups was different, but not statistically significant (p=0.8328. CONCLUSION: Knowledge about

  11. Doação de alimentos como ação emergencial de combate à fome – subsídios aos COMSEAS

    OpenAIRE

    Boog, Maria Cristina Faber

    2015-01-01

    Os Conselhos Municipais de Segurança Alimentar – COMSEAs têm por função propor as diretrizes gerais da Política de Segurança Alimentar e Nutricional a serem implementadas pelos órgãos executores. Freqüentemente os membros dos Conselhos Municipais de Segurança Alimentar precisam posicionar-se em relação às ações emergenciais de combate à fome, ou seja, à doação de alimentos (CONSEA, 2006). Vários fatores de ordem técnica e ética precisam ser considerados na tomada de decisão sobre a pertinênci...

  12. Contribuições para a efetividade da comunicação da doação de sangue a partir de uma abordagem persuasiva

    OpenAIRE

    Ludwig, Silvia Terra

    2010-01-01

    A doação de sangue é uma necessidade para países e pessoas. O crescimento da violência, dos acidentes de trânsito, junto com a disseminação de doenças transmissíveis e com o envelhecimento da população, trazem dificuldades aos hemocentros e instituições de saúde para assegurar um adequado e consistente suprimento de sangue para atender às necessidades dos pacientes. São realizadas campanhas via TV, rádio, jornal, etc, e foi observado que as pessoas se sensibilizam com a necessidade de sangue,...

  13. MAX-DOAS measurements in southern China: retrieval of aerosol extinctions and validation using ground-based in-situ data

    Directory of Open Access Journals (Sweden)

    X. Li

    2010-03-01

    Full Text Available We performed MAX-DOAS measurements during the PRiDe-PRD2006 campaign in the Pearl River Delta region 50 km north of Guangzhou, China, for 4 weeks in June 2006. We used an instrument sampling at 7 different elevation angles between 3° and 90°. During 9 cloud-free days, differential slant column densities (DSCDs of O4 (O2 dimer absorptions between 351 nm and 389 nm were evaluated for 6 elevation angles. Here, we show that radiative transfer modeling of the DSCDS can be used to retrieve the aerosol extinction and the height of the boundary layer. A comparison of the aerosol extinction with simultaneously recorded, ground based nephelometer data shows excellent agreement.

  14. Maximum-likelihood methods for array processing based on time-frequency distributions

    Science.gov (United States)

    Zhang, Yimin; Mu, Weifeng; Amin, Moeness G.

    1999-11-01

    This paper proposes a novel time-frequency maximum likelihood (t-f ML) method for direction-of-arrival (DOA) estimation for non- stationary signals, and compares this method with conventional maximum likelihood DOA estimation techniques. Time-frequency distributions localize the signal power in the time-frequency domain, and as such enhance the effective SNR, leading to improved DOA estimation. The localization of signals with different t-f signatures permits the division of the time-frequency domain into smaller regions, each contains fewer signals than those incident on the array. The reduction of the number of signals within different time-frequency regions not only reduces the required number of sensors, but also decreases the computational load in multi- dimensional optimizations. Compared to the recently proposed time- frequency MUSIC (t-f MUSIC), the proposed t-f ML method can be applied in coherent environments, without the need to perform any type of preprocessing that is subject to both array geometry and array aperture.

  15. A importância da educação na promoção da doação de órgãos

    OpenAIRE

    Taise Ribeiro Morais; Maricelma Ribeiro Morais

    2012-01-01

    O transplante e a doação de órgãos humanos são temas polêmicos que têm despertado interesse e discussões. A falta de esclarecimento e o noticiário sensacionalista sobre tráfico de órgãos contribuem para aumentar dúvidas e tornar permanentes os mitos e preconceitos.A doação de órg��os e tecidos é vista pela sociedade, em geral, como um ato de solidariedade e amor dos familiares. No entanto, ela exige a tomada de decisão num momento de extrema dor e angústia, motivado pelo impacto da notí...

  16. Opinião e conhecimento da população da cidade de curitiba sobre doação e transplante de órgãos

    OpenAIRE

    Coelho,Julio Cezar Uili; Cilião,Camilla; Parolin,Mônica Beatriz; Freitas,Alexandre Coutinho Teixeira de; Gama Filho,Ózimo Pereira; Saad,Danilo Tatim; Pistori,Rafael Petracca; Martone,Daniel

    2007-01-01

    OBJETIVOS: Determinar a opinião e o conhecimento, de uma amostra da população da cidade de Curitiba, sobre doação e transplante de órgãos. MÉTODOS: A opinião e o conhecimento sobre doação e transplante de órgãos de mil pessoas, com idade superior a 18 anos, foram determinados através de um questionário de 20 perguntas. Os entrevistados avaliados tinham uma distribuição similar em idade, sexo e padrão socioeconômico, e escolaridade à população brasileira, determinada pelo IBGE. RESULTADOS: A m...

  17. Implementation of QR-decomposition based on CORDIC for unitary MUSIC algorithm

    Science.gov (United States)

    Lounici, Merwan; Luan, Xiaoming; Saadi, Wahab

    2013-07-01

    The DOA (Direction Of Arrival) estimation with subspace methods such as MUSIC (MUltiple SIgnal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique) is based on an accurate estimation of the eigenvalues and eigenvectors of covariance matrix. QR decomposition is implemented with the Coordinate Rotation DIgital Computer (CORDIC) algorithm. QRD requires only additions and shifts [6], so it is faster and more regular than other methods. In this article the hardware architecture of an EVD (Eigen Value Decomposition) processor based on TSA (triangular systolic array) for QR decomposition is proposed. Using Xilinx System Generator (XSG), the design is implemented and the estimated logic device resource values are presented for different matrix sizes.

  18. The CU 2-D-MAX-DOAS instrument – Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Ivan; Coburn, Sean; Berg, Larry K.; Lantz, Kathy; Michalsky, Joseph; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

    2016-01-01

    The multiannual global mean of aerosol optical depth at 550 nm (AOD550) over land is ~0.19, and that over oceans is ~0.13. About 45 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity. We employ radiative transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD430 < 0.13) we compare RSP-based retrievals of AOD430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD430 is +0.012 ± 0.023 (CIMEL), -0.012 ± 0.024 (MFRSR), -0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMELAOD - MFRSRAOD) and yields the following

  19. Doação de órgãos: compreensão na perspectiva de adolescentes Organ donation: the opinion of adolescents

    Directory of Open Access Journals (Sweden)

    Ana Maria de Carvalho Monteiro

    2011-12-01

    Full Text Available OBJETIVOS: conhecer a perspectiva dos adolescentes sobre doação de órgãos. MÉTODOS: estudo descritivo, exploratório, de abordagem qualitativa, com 13 adolescentes entre 16 a 19 anos, de duas escolas públicas do Recife/PE. A coleta dos dados ocorreu de fevereiro a maio de 2008 com entrevistas semiestruturadas, submetidas à análise de conteúdo na modalidade temática. RESULTADOS: identificaram-se quatro temáticas: concepções que podem salvar vidas; conhecimentos revelados; sentimentos facilitadores e complicadores para a doação de órgãos; outras influências que repercutem na decisão de doar órgãos. Os adolescentes demonstraram desejo de salvar vidas doando órgãos, porém, não suficiente para uma tomada de decisão. A influência da família, mídia e amigos, surgiu como fator positivo ou de resistência, e a possibilidade de contribuir para a continuidade da vida funcionou positivamente na decisão. CONCLUSÕES: Na ótica dos adolescentes, a doação de órgãos é necessária e eles desejam contribuir, porém seus conhecimentos são inadequados. Há necessidade de informações sistemáticas e precisas para tornar realidade seu desejo em doar órgãos e salvar vidas.OBJECTIVES: to learn the opinion of adolescents regarding organ donation. METHODS: a descriptive, exploratory, qualitative study was carried out with 13 adolescents aged between 16 and 19 years at two public schools in Recife, in the Brazilian State of Pernambuco. Data were collected between February and May 2008 in semi-structured interviews that were subsequently subjected to themed content analysis. RESULTS: for themes were identified: the idea of saving lives; knowledge revealed; helpful and unhelpful feelings regarding organ donation; other issues that influence the decision to donate organs. The adolescents showed a willingness to save lives by donating organs, although this was not sufficient for them to make a decision to do so. The influence of family

  20. Dioktil Adipat (DOA 'ın Sparus aurata (Çipura karaciğer ve solungaç histolojisi üzerine etkileri.

    Directory of Open Access Journals (Sweden)

    Melih Üreten

    2015-12-01

    Full Text Available Polimer üretim süreçlerinde ikincil plastikleştirici olarak çok yaygın kullanılan dioktil adipat (DOA ’ın ekotoksikolojik etkileri ayrıntılı olarak araştırılmamıştır. Bu çalışmanın amacı 15 gün süreyle 250, 500 ve 750 ppm DOA’ya maruz bırakılan erkek çipura balıklarının (Sparus aurata solungaç ve karaciğerlerindeki histopatolojik değişimlerin ışık mikroskobu ile belirlenmesidir. Kontrol grubuyla karşılaştırıldığında, deneme grubu örneklerinin solungaçlarında vakuolizasyon, merkezi venada genişleme ve çarpıcı füzyon olarak ayırt edilen önemli histopatolojik değişimler gözlenmiştir. Ayrıca solungacın epitel, pillar mukus ve mitokondri zengini hücrelerinde belirgin hipertrofi ve hiperplazi de not edilmiştir. DOA’ya maruz bırakılan balıkların karaciğerlerinin incelenmesi yağlanma, fibrozis ve nekrozis olarak bir dizi hepatosellüler değişim ortaya koymuştur. Kanamaya ek olarak parankimatik sinüzoidler ve hepatopankreasın merkezi venleri genişlemiştir. Çalışma, DOA etkisinin araştırılan her iki dokuda da çoklu histolojik değişimlere yol açtığını, üstelik bu değişimlerin hepsinin uygulanan kimyasalın artan konsantrasyonuyla bağlantılı olduğunu göstermektedir. Sonuçta DOA’nın bir sucul kirletici olarak daha fazla dikkate alınması gerektiği vurgulanmıştır

  1. Measurements of O3, NO2 and BrO during the INDOEX campaign using ground based DOAS and GOME satellite data

    Directory of Open Access Journals (Sweden)

    A. Ladstätter-Weißenmayer

    2007-01-01

    Full Text Available The INDian Ocean EXperiment (INDOEX was an international, multi-platform field campaign to measure long-range transport of air masses from South and South-East-(SE Asia towards the Indian Ocean. During the dry monsoon season between January and March 1999, local measurements were carried out from ground based platforms and were compared with satellite based data. The objective of this study was to characterise stratospheric and tropospheric trace gas amounts in the equatorial region, and to investigate the impact of air pollution at this remote site. For the characterisation of the chemical composition of the outflow from the S-SE-Asian region, we performed ground based dual-axis-DOAS (Differential Optical Absorption Spectroscopy measurements at the KCO (Kaashidhoo Climate Observatory in the Maldives (5.0° N, 73.5° E. The measurements were conducted using two different observation modes (off-axis and zenith-sky. This technique allows the separation of the tropospheric and stratospheric columns for different trace gases like O3 and NO2. These dual-axis DOAS data were compared with O3-sonde measurements performed at KCO and satellite based GOME (Global Ozone Measuring Experiment data during the intensive measuring phase of the INDOEX campaign in February and March 1999. From GOME observations, tropospheric and stratospheric columns for O3 and NO2 were retrieved. In addition, the analysis of the O3-sonde measurements allowed the determination of the tropospheric O3 amount. The comparison shows that the results of all three measurement systems agree within their error limits. During the INDOEX campaign, mainly background conditions were observed, but in a single case an increase of tropospheric NO2 during a short pollution event was observed from the ground and the impact on the vertical columns was calculated. GOME measurements showed evidence for small tropospheric contributions to the BrO budget, probably located in the free troposphere and

  2. Os conflitos do consentimento acerca da doação de órgãos post mortem no Brasil

    Directory of Open Access Journals (Sweden)

    MAYNARD, Lorena Oliveira Dantas

    2015-11-01

    Full Text Available Com o refinamento das técnicas de cirurgias e imunogenética pela medicina nas últimas décadas e com os avanços na farmacoterapia, o transplante de órgãos e tecidos tornou-se uma possibilidade real e uma alternativa essencial ao prolongamento e à qualidade da vida humana. Este estudo objetivou analisar o consentimento para remoção de órgãos e tecidos post mortem na legislação brasileira, na perspectiva da autorização da família. Adotou-se, para tanto, estratégia metodológica qualitativa através de revisão de literatura e revisão legislativa, que permitem um aprofundamento no universo dos significados, dos motivos, das aspirações, das crenças, dos valores e das atitudes em relação ao tema. Os resultados apontam que, na atual Lei de Transplantes, os direitos da personalidade e o princípio da autonomia da vontade são institutos pouco homenageados em função da predominância do monopólio da decisão familiar na hipótese de um confronto entre a vontade do doador e a vontade da família. Frente ao problema da escassez de órgãos no país, a solução mais consentânea com a justiça seria uma adequação entre os dispositivos de lei do Código Civil e a Lei de Transplantes. Oportuno partir do texto já existente do artigo 4º da Lei n. 9.434/1997, para incluir a manifestação da vontade do doador em vida, devidamente documentada. É igualmente importante a informação e a conscientização popular sobre a natureza humanitária da doação de órgãos como medidas direcionadas à discussão do princípio da solidariedade para uma política de doação de órgãos.

  3. Conhecimento da população do município de Valparaíso de Goiás sobre o processo de doação de órgãos para transplantes

    Directory of Open Access Journals (Sweden)

    Micaella Bento Felix

    2017-12-01

    Full Text Available Nos últimos anos, a política dos transplantes de órgãos tem sidouma das políticas de saúde mais trabalhadas em nosso país. O objetivodeste estudo foi verificar o conhecimento da população domunicípio de Valparaíso, GO, sobre o processo de doação de órgãospara transplantes. Trata-se de um estudo de campo de abordagemquantitativa, do tipo descritivo exploratório, utilizando como instrumentopara coleta de dados um questionário com 15 perguntasfechadas. O estudo foi realizado com moradores do município deValparaíso de Goiás, selecionados aleatoriamente, dentre a populaçãocom idade acima de 18 anos. Os dados foram coletados na sala deespera do Hospital Municipal de Valparaíso e nos domicílios. Todo oestudo obedeceu a Resolução 466/12. Os resultados demonstraramque a população possui informações sobre doação de órgãos, citandoos meios de comunicação em massa. A maioria das pessoas entrevistadasé favorável à doação, justificando que seus órgãos ajudariamoutras pessoas. Os dados demonstraram que o principal fator derecusa à doação foi a falta de confiança no sistema de saúde brasileiro.Conclui-se que é necessária a adoção de medidas educativas, a fim deesclarecer a população a respeito de todas as etapas e conceitos envolvidosno processo de doação de órgãos e tecidos para transplante.Palavras-chave: Conhecimento; Obtenção de tecidos e órgãos;Enfermagem.

  4. Robust regularized least-squares beamforming approach to signal estimation

    KAUST Repository

    Suliman, Mohamed Abdalla Elhag

    2017-05-12

    In this paper, we address the problem of robust adaptive beamforming of signals received by a linear array. The challenge associated with the beamforming problem is twofold. Firstly, the process requires the inversion of the usually ill-conditioned covariance matrix of the received signals. Secondly, the steering vector pertaining to the direction of arrival of the signal of interest is not known precisely. To tackle these two challenges, the standard capon beamformer is manipulated to a form where the beamformer output is obtained as a scaled version of the inner product of two vectors. The two vectors are linearly related to the steering vector and the received signal snapshot, respectively. The linear operator, in both cases, is the square root of the covariance matrix. A regularized least-squares (RLS) approach is proposed to estimate these two vectors and to provide robustness without exploiting prior information. Simulation results show that the RLS beamformer using the proposed regularization algorithm outperforms state-of-the-art beamforming algorithms, as well as another RLS beamformers using a standard regularization approaches.

  5. OMI satellite observed formaldehyde column from 2006 to 2015 over Xishuangbanna, southwest China, and validation using ground based zenith-sky DOAS.

    Science.gov (United States)

    Liu, Rui; Feng, Tao; Wang, Shanshan; Shi, Chanzhen; Guo, Yanlin; Nan, Jialiang; Deng, Yun; Zhou, Bin

    2018-02-01

    Formaldehyde (HCHO) provides a proxy to reveal the isoprene and biogenic volatile organic compounds emission which plays important roles in atmospheric chemical process and climate change. The ground-based observation with zenith-sky DOAS is carried out in order to validate the HCHO columns from OMI. It has a good correlation of 0.71678 between the HCHO columns from two sources. Then we use the OMI HCHO columns from January 2006 to December 2015 to indicate the interannual variation and spatial distribution in Xishuangbanna. The HCHO concentration peaks appeared in March or April for each year significantly corresponding to the intensive fire counts at the same time, which illustrate that the high HCHO columns are strongly influenced by the biomass burning in spring. Temperature and precipitation are also the important influence factors in the seasonal variation when there is nearly no biomass burning. The spatial patterns over the past ten years strengthen the deduction from the temporal variation and show the relationship with land cover and land use, elevation and population density. It is concluded that the biogenic activity plays a role in controlling the background level of HCHO in Xishuangbanna, while biomass burning is the main driving force of high HCHO concentration. And forests are greater contributor to HCHO rather than rubber trees which cover over 20% of the land in the region. Moreover, uncertainties from HCHO slant column retrieval and AMFs calculation are discussed in detail. Copyright © 2017. Published by Elsevier B.V.

  6. Marketing social para doação de sangue: análise da predisposição de novos doadores

    Directory of Open Access Journals (Sweden)

    Stephanie Ingrid Souza Barboza

    2014-07-01

    Full Text Available Este artigo objetiva compreender os fatores motivacionais que influenciam os indivíduos a doarem sangue, com a finalidade de subsidiar as ações de marketing social orientadas à captação de novos doadores. Com base em uma revisão teórica, um modelo de hipóteses foi elaborado, para análise de influências e interações de construtos na formação da predisposição das pessoas a serem doadores de sangue. Foi feito o levantamento de campo por meio de um questionário estruturado, junto a uma amostra de 346 pessoas. Para análise, foram usadas técnicas de análise descritiva, avaliação de consistência psicométrica e modelagem de equações estruturais com estimação por mínimos quadrados parciais. Como resultados, verificou-se principalmente que há uma influência negativa do medo e positiva do grupo de referência na predisposição dos sujeitos em doar sangue. Isso indicou que as ações de marketing social para a doação de sangue são mais eficientes em incentivar novos doadores se mantiverem foco nesses dois fatores.

  7. Phase Centers of Subapertures in a Tapered Aperture Array.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  8. Tracking a convoy of multiple targets using acoustic sensor data

    Science.gov (United States)

    Damarla, T. R.

    2003-08-01

    In this paper we present an algorithm to track a convoy of several targets in a scene using acoustic sensor array data. The tracking algorithm is based on template of the direction of arrival (DOA) angles for the leading target. Often the first target is the closest target to the sensor array and hence the loudest with good signal to noise ratio. Several steps were used to generate a template of the DOA angle for the leading target, namely, (a) the angle at the present instant should be close to the angle at the previous instant and (b) the angle at the present instant should be within error bounds of the predicted value based on the previous values. Once the template of the DOA angles of the leading target is developed, it is used to predict the DOA angle tracks of the remaining targets. In order to generate the tracks for the remaining targets, a track is established if the angles correspond to the initial track values of the first target. Second the time delay between the first track and the remaining tracks are estimated at the highest correlation points between the first track and the remaining tracks. As the vehicles move at different speeds the tracks either compress or expand depending on whether a target is moving fast or slow compared to the first target. The expansion and compression ratios are estimated and used to estimate the predicted DOA angle values of the remaining targets. Based on these predicted DOA angles of the remaining targets the DOA angles obtained from the MVDR or Incoherent MUSIC will be appropriately assigned to proper tracks. Several other rules were developed to avoid mixing the tracks. The algorithm is tested on data collected at Aberdeen Proving Ground with a convoy of 3, 4 and 5 vehicles. Some of the vehicles are tracked and some are wheeled vehicles. The tracking algorithm results are found to be good. The results will be presented at the conference and in the paper.

  9. Double-Capon and double-MUSICAL for arrival separation and observable estimation in an acoustic waveguide

    Science.gov (United States)

    Touzé, Grégoire Le; Nicolas, Barbara; Mars, Jérôme I.; Roux, Philippe; Oudompheng, Benoit

    2012-12-01

    Recent developments in shallow water ocean acoustic tomography propose the use of an original configuration composed of two source-receiver vertical arrays and wideband sources. The recording space thus has three dimensions, with two spatial dimensions and the frequency dimension. Using this recording space, it is possible to build a three-dimensional (3D) estimation space that gives access to the three observables associated with the acoustic arrivals: the direction of departure, the direction of arrivals, and the time of arrival. The main interest of this 3D estimation space is its capability for the separation of acoustic arrivals that usually interfere in the recording space, due to multipath propagation. A 3D estimator called double beamforming has already been developed, although it has limited resolution. In this study, the new 3D high-resolution estimators of double Capon and double MUSICAL are proposed to achieve this task. The ocean acoustic tomography configuration allows a single recording realization to estimate the cross-spectral data matrix, which is necessary to build high-resolution estimators. 3D smoothing techniques are thus proposed to increase the rank of the matrix. The estimators developed are validated on real data recorded in an ultrasonic tank, and their detection performances are compared to existing 2D and 3D methods.

  10. 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.

  11. Feedback Robust Cubature Kalman Filter for Target Tracking Using an Angle Sensor.

    Science.gov (United States)

    Wu, Hao; Chen, Shuxin; Yang, Binfeng; Chen, Kun

    2016-05-09

    The direction of arrival (DOA) tracking problem based on an angle sensor is an important topic in many fields. In this paper, a nonlinear filter named the feedback M-estimation based robust cubature Kalman filter (FMR-CKF) is proposed to deal with measurement outliers from the angle sensor. The filter designs a new equivalent weight function with the Mahalanobis distance to combine the cubature Kalman filter (CKF) with the M-estimation method. Moreover, by embedding a feedback strategy which consists of a splitting and merging procedure, the proper sub-filter (the standard CKF or the robust CKF) can be chosen in each time index. Hence, the probability of the outliers' misjudgment can be reduced. Numerical experiments show that the FMR-CKF performs better than the CKF and conventional robust filters in terms of accuracy and robustness with good computational efficiency. Additionally, the filter can be extended to the nonlinear applications using other types of sensors.

  12. A doação de sangue sob a ótica de escolares: concepções e valores Blood donation in the view of schoolchildren: conceptions and values

    Directory of Open Access Journals (Sweden)

    Regina Pagotto Bossolan

    2011-01-01

    Full Text Available Nesta pesquisa investigou-se o nível de informação, percepção, motivos e sentimentos de escolares sobre a doação de sangue. 145 escolares do pré, 2ª, 4ª séries com seis, oito e 10 anos de idade foram submetidos a provas piagetianas, responderam uma entrevista, se posicionaram frente a um dilema. Verificou-se pouca informação e informações errôneas sobre a doação. A escola foi a fonte de informação menos citada. A maioria dos entrevistados tanto na entrevista, como no dilema, justificou a doação de sangue como um ato solidário, permitindo supor que valores como generosidade podem ser adquiridos na fase pré-operatória. Discute-se o papel da escola nos programas de Educação em Saúde voltados a comportamentos que serão emitidos a longo prazo e que beneficiam a coletividade.This study investigated children's values and perceptions of blood donation. A hundred forty-five students (preschool, second- and fourth-graders aged 6, 8 and 10 years old answered Piagetian tests. They were also interviewed on blood donation and faced a moral dilemma. Lack of information and misinformation were observed. The school was the least frequently cited information source. Findings showed that the participants justified blood donation as an act of solidarity. It indicates that children have a conception of values since the preoperational stage of cognitive development. It is also presented a discussion on the role of schools in Health Care Education, particularly targeting specific behaviors which will be expressed in the long term such as blood donation.

  13. Four-dimensional parameter estimation of plane waves using swarming intelligence

    International Nuclear Information System (INIS)

    Zaman Fawad; Munir Fahad; Khan Zafar Ullah; Qureshi Ijaz Mansoor

    2014-01-01

    This paper proposes an efficient approach for four-dimensional (4D) parameter estimation of plane waves impinging on a 2-L shape array. The 4D parameters include amplitude, frequency and the two-dimensional (2D) direction of arrival, namely, azimuth and elevation angles. The proposed approach is based on memetic computation, in which the global optimizer, particle swarm optimization is hybridized with a rapid local search technique, pattern search. For this purpose, a new multi-objective fitness function is used. This fitness function is the combination of mean square error and the correlation between the normalized desired and estimated vectors. The proposed hybrid scheme is not only compared with individual performances of particle swarm optimization and pattern search, but also with the performance of the hybrid genetic algorithm and that of the traditional approach. A large number of Monte—Carlo simulations are carried out to validate the performance of the proposed scheme. It gives promising results in terms of estimation accuracy, convergence rate, proximity effect and robustness against noise. (interdisciplinary physics and related areas of science and technology)

  14. Multiple Signal Classification for Gravitational Wave Burst Search

    Science.gov (United States)

    Cao, Junwei; He, Zhengqi

    2013-01-01

    This work is mainly focused on the application of the multiple signal classification (MUSIC) algorithm for gravitational wave burst search. This algorithm extracts important gravitational wave characteristics from signals coming from detectors with arbitrary position, orientation and noise covariance. In this paper, the MUSIC algorithm is described in detail along with the necessary adjustments required for gravitational wave burst search. The algorithm's performance is measured using simulated signals and noise. MUSIC is compared with the Q-transform for signal triggering and with Bayesian analysis for direction of arrival (DOA) estimation, using the Ω-pipeline. Experimental results show that MUSIC has a lower resolution but is faster. MUSIC is a promising tool for real-time gravitational wave search for multi-messenger astronomy.

  15. On the influence of microphone array geometry on HRTF-based Sound Source Localization

    DEFF Research Database (Denmark)

    Farmani, Mojtaba; Pedersen, Michael Syskind; Tan, Zheng-Hua

    2015-01-01

    The direction dependence of Head Related Transfer Functions (HRTFs) forms the basis for HRTF-based Sound Source Localization (SSL) algorithms. In this paper, we show how spectral similarities of the HRTFs of different directions in the horizontal plane influence performance of HRTF-based SSL...... algorithms; the more similar the HRTFs of different angles to the HRTF of the target angle, the worse the performance. However, we also show how the microphone array geometry can assist in differentiating between the HRTFs of the different angles, thereby improving performance of HRTF-based SSL algorithms....... Furthermore, to demonstrate the analysis results, we show the impact of HRTFs similarities and microphone array geometry on an exemplary HRTF-based SSL algorithm, called MLSSL. This algorithm is well-suited for this purpose as it allows to estimate the Direction-of-Arrival (DoA) of the target sound using any...

  16. A fast computation method for MUSIC spectrum function based on circular arrays

    Science.gov (United States)

    Du, Zhengdong; Wei, Ping

    2015-02-01

    The large computation amount of multiple signal classification (MUSIC) spectrum function seriously affects the timeliness of direction finding system using MUSIC algorithm, especially in the two-dimensional directions of arrival (DOA) estimation of azimuth and elevation with a large antenna array. This paper proposes a fast computation method for MUSIC spectrum. It is suitable for any circular array. First, the circular array is transformed into a virtual uniform circular array, in the process of calculating MUSIC spectrum, for the cyclic characteristics of steering vector, the inner product in the calculation of spatial spectrum is realised by cyclic convolution. The computational amount of MUSIC spectrum is obviously less than that of the conventional method. It is a very practical way for MUSIC spectrum computation in circular arrays.

  17. Nullspace MUSIC and Improved Radio Frequency Emitter Geolocation from a Mobile Antenna Array

    Science.gov (United States)

    Kintz, Andrew L.

    This work advances state-of-the-art Radio Frequency (RF) emitter geolocation from an airborne or spaceborne antenna array. With an antenna array, geolocation is based on Direction of Arrival (DOA) estimation algorithms such as MUSIC. The MUSIC algorithm applies to arbitrary arrays of polarization sensitive antennas and yields high resolution. However, MUSIC fails to obtain its theoretical resolution for simultaneous, closely spaced, co-frequency signals. We propose the novel Nullspace MUSIC algorithm, which outperforms MUSIC and its existing modifications while maintaining MUSIC(apostrophe)s fundamental orthogonality test. Nullspace MUSIC applies a divide-and-conquer approach and estimates a single DOA at a time. Additionally, an antenna array on an aircraft cannot be perfectly calibrated. RF waves are blocked, reflected, and scattered in a time-varying fashion by the platform around the antenna array. Consequently, full-wave electromagnetics simulations or demanding measurements of the entire platform cannot eliminate the mismatch between the true, in-situ antenna patterns and the antenna patterns that are available for DOA estimation (the antenna array manifold). Platform-induced manifold mismatch severely degrades MUSIC(apostrophe)s resolution and accuracy. We show that Nullspace MUSIC improves DOA accuracy for well separated signals that are incident on an airborne antenna array. Conventionally, geolocation from a mobile platform draws Lines of Bearing (LOB) from the antenna array along the DOAs to find the locations where the DOAs intersect with the ground. However, averaging the LOBs in the global coordinate system yields large errors due to geometric dilution of precision. Since averaging positions fails, a single emitter is typically located by finding the position on the ground that yields the Minimum Apparent Angular Error (MAAE) for the DOA estimates over a flight. We extend the MAAE approach to cluster LOBs from multiple emitters. MAAE clustering

  18. An Improved Direction Finding Algorithm Based on Toeplitz Approximation

    Directory of Open Access Journals (Sweden)

    Qing Wang

    2013-01-01

    Full Text Available In this paper, a novel direction of arrival (DOA estimation algorithm called the Toeplitz fourth order cumulants multiple signal classification method (TFOC-MUSIC algorithm is proposed through combining a fast MUSIC-like algorithm termed the modified fourth order cumulants MUSIC (MFOC-MUSIC algorithm and Toeplitz approximation. In the proposed algorithm, the redundant information in the cumulants is removed. Besides, the computational complexity is reduced due to the decreased dimension of the fourth-order cumulants matrix, which is equal to the number of the virtual array elements. That is, the effective array aperture of a physical array remains unchanged. However, due to finite sampling snapshots, there exists an estimation error of the reduced-rank FOC matrix and thus the capacity of DOA estimation degrades. In order to improve the estimation performance, Toeplitz approximation is introduced to recover the Toeplitz structure of the reduced-dimension FOC matrix just like the ideal one which has the Toeplitz structure possessing optimal estimated results. The theoretical formulas of the proposed algorithm are derived, and the simulations results are presented. From the simulations, in comparison with the MFOC-MUSIC algorithm, it is concluded that the TFOC-MUSIC algorithm yields an excellent performance in both spatially-white noise and in spatially-color noise environments.

  19. Application Research of the Sparse Representation of Eigenvector on the PD Positioning in the Transformer Oil

    Directory of Open Access Journals (Sweden)

    Qing Xie

    2016-01-01

    Full Text Available The partial discharge (PD detection of electrical equipment is important for the safe operation of power system. The ultrasonic signal generated by the PD in the oil is a broadband signal. However, most methods of the array signal processing are used for the narrowband signal at present, and the effect of some methods for processing wideband signals is not satisfactory. Therefore, it is necessary to find new broadband signal processing methods to improve detection ability of the PD source. In this paper, the direction of arrival (DOA estimation method based on sparse representation of eigenvector is proposed, and this method can further reduce the noise interference. Moreover, the simulation results show that this direction finding method is feasible for broadband signal and thus improve the following positioning accuracy of the three-array localization method. And experimental results verify that the direction finding method based on sparse representation of eigenvector is feasible for the ultrasonic array, which can achieve accurate estimation of direction of arrival and improve the following positioning accuracy. This can provide important guidance information for the equipment maintenance in the practical application.

  20. Vector-Sensor MUSIC for Polarized Seismic Sources Localization

    Directory of Open Access Journals (Sweden)

    Jérôme I. Mars

    2005-01-01

    Full Text Available This paper addresses the problem of high-resolution polarized source detection and introduces a new eigenstructure-based algorithm that yields direction of arrival (DOA and polarization estimates using a vector-sensor (or multicomponent-sensor array. This method is based on separation of the observation space into signal and noise subspaces using fourth-order tensor decomposition. In geophysics, in particular for reservoir acquisition and monitoring, a set of Nx-multicomponent sensors is laid on the ground with constant distance Δx between them. Such a data acquisition scheme has intrinsically three modes: time, distance, and components. The proposed method needs multilinear algebra in order to preserve data structure and avoid reorganization. The data is thus stored in tridimensional arrays rather than matrices. Higher-order eigenvalue decomposition (HOEVD for fourth-order tensors is considered to achieve subspaces estimation and to compute the eigenelements. We propose a tensorial version of the MUSIC algorithm for a vector-sensor array allowing a joint estimation of DOA and signal polarization estimation. Performances of the proposed algorithm are evaluated.

  1. A closed-form solution for moving source localization using LBI changing rate of phase difference only

    Directory of Open Access Journals (Sweden)

    Zhang Min

    2014-04-01

    Full Text Available Due to the deficiencies in the conventional multiple-receiver localization systems based on direction of arrival (DOA such as system complexity of interferometer or array and amplitude/phase unbalance between multiple receiving channels and constraint on antenna configuration, a new radiated source localization method using the changing rate of phase difference (CRPD measured by a long baseline interferometer (LBI only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square (PLS method, and then in the second stage, the source position and velocity are found by another PLS minimization. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable (IV method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer–Rao lower bound (CRLB and mean square error (MSE are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.

  2. Improved Coarray Interpolation Algorithms with Additional Orthogonal Constraint for Cyclostationary Signals

    Directory of Open Access Journals (Sweden)

    Jinyang Song

    2018-01-01

    Full Text Available Many modulated signals exhibit a cyclostationarity property, which can be exploited in direction-of-arrival (DOA estimation to effectively eliminate interference and noise. In this paper, our aim is to integrate the cyclostationarity with the spatial domain and enable the algorithm to estimate more sources than sensors. However, DOA estimation with a sparse array is performed in the coarray domain and the holes within the coarray limit the usage of the complete coarray information. In order to use the complete coarray information to increase the degrees-of-freedom (DOFs, sparsity-aware-based methods and the difference coarray interpolation methods have been proposed. In this paper, the coarray interpolation technique is further explored with cyclostationary signals. Besides the difference coarray model and its corresponding Toeplitz completion formulation, we build up a sum coarray model and formulate a Hankel completion problem. In order to further improve the performance of the structured matrix completion, we define the spatial spectrum sampling operations and the derivative (conjugate correlation subspaces, which can be exploited to construct orthogonal constraints for the autocorrelation vectors in the coarray interpolation problem. Prior knowledge of the source interval can also be incorporated into the problem. Simulation results demonstrate that the additional constraints contribute to a remarkable performance improvement.

  3. Direction Finding for Bistatic MIMO Radar with Uniform Circular Array

    Directory of Open Access Journals (Sweden)

    Cao Yunhe

    2013-01-01

    Full Text Available A method of direction of arrival (DOA and direction of departure (DOD angle estimation based on polynomial rooting for bistatic multiple-input multiple-output (MIMO radar with uniform circular array (UCA configuration is proposed in this paper. The steering vector of the UCA is firstly transformed into a steering vector with a Vandermonde structure by using the Jacobi-Anger expansion. Then the null-spectrum function of the MIMO radar can be written as an expression in which the transmit and receive steering vectors are decoupled. Finally, a two-step polynomial rooting is used to estimate DOA and DOD of targets instead of two-dimensional multiple signal classification (MUSIC search method for bistatic UCA MIMO radar. The angle estimation performance of the proposed method is similar to that of the MUSIC spectral search method, but the computation burden of the proposed polynomial rooting algorithm is much lower than that of the conventional MUSIC method. The simulation results of the proposed algorithm are presented and the performances are investigated and analyzed.

  4. Measurement of Rank and Other Properties of Direct and Scattered Signals

    Directory of Open Access Journals (Sweden)

    Svante Björklund

    2016-01-01

    Full Text Available We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments.

  5. Doação de leite humano: experiência de mulheres doadoras Donación de leche humana: experiencia de mujeres donantes Breast milk donation: women's donor experience

    Directory of Open Access Journals (Sweden)

    Lucienne Christine Estevez de Alencar

    2009-02-01

    Full Text Available OBJETIVO: Descrever características do comportamento de doação e identificar motivos, crenças e sentimentos relativos a essa prática, segundo relatos de mulheres doadoras. Foram investigados ainda aspectos pessoais e socioambientais de mulheres doadoras e ex-doadoras que parecem afetar a conduta de doação. MÉTODOS: Foi realizado estudo exploratório, descritivo e transversal com mulheres doadoras cadastradas em dois bancos de leite da rede pública de saúde do Distrito Federal, com coleta de dados no período de julho a setembro de 2005. Participaram 36 mulheres com idades que variaram de 14 a 33 anos (média=24,78; dp=5,22, com diferentes níveis de escolaridade, sendo 58,3% primigestas. O procedimento de coleta de dados baseou-se em entrevistas domiciliares. Além das análises estatísticas descritivas, procedeu-se à análise de conteúdo categorial dos dados qualitativos. RESULTADOS: Os motivos mais citados para a doação de leite foram altruísmo e excesso de produção lática. O intervalo de tempo mais freqüente para a concretização da doação foi de 13 dias após o parto. Contato telefônico com o banco de leite foi a conduta adotada pela maioria das participantes (n=22 para obtenção de informações que favoreceram o início do processo de doação. CONCLUSÕES: Foram identificados aspectos psicossociais e experiências de mulheres doadoras que poderão contribuir para o fortalecimento da rede de apoio social formal e informal para doação, além de servir de estímulo para a implementação de estratégias técnicas e políticas que favoreçam a prática de doação.OBJETIVO: Describir características del comportamiento de donación e identificar motivos, creencias y sentimientos relacionados con esa práctica, según relatos de mujeres donantes. Fueron investigados también aspectos personales y socioambientales de mujeres donantes y ex-donantes que parecen afectar la conducta de donación. MÉTODOS: Fue realizado

  6. Conhecimento e opinião de estudantes de medicina sobre doação e transplante de órgãos Attitude and opinion of medical students about organ donation and transplantation

    Directory of Open Access Journals (Sweden)

    Flavio H.F. Galvao

    2007-10-01

    Full Text Available OBJETIVOS: Analisar o conhecimento e a opinião de estudantes de medicina sobre doação e transplante de órgãos. MÉTODOS: Trezentos e quarenta e sete estudantes responderam, voluntariamente, questionário com 17 perguntas sobre doação e transplante de órgãos. Eles foram avaliados globalmente, para verificar tendências gerais, e agrupados de acordo com o seu ano no curso médico (primeiro ao sexto, para avaliar diferenças entre os períodos. Alunos do quinto e sexto ano foram reunidos em um só grupo. Os resultados foram analisados pelo teste Qui quadrado. RESULTADOS: A intenção de ser doador post mortem foi de 89% e intervivo de 90%, contudo, apenas 62% sabiam dos riscos da doação intervivo. Entre os 347 estudantes, 70% admitiram conhecimento regular, ruim ou péssimo do assunto, 90,2% consideraram importante o tema transplante para a graduação médica, 76,9% consideraram o consentimento informado/expresso como o melhor critério de doação e 64,3% optaram pela gravidade da doença do paciente como melhor forma de alocação. O entendimento sobre transplante aumentou conforme o avanço no curso de graduação. Estudantes do quarto, quinto e sexto ano adotaram atitude negativa, em comparação aos dos anos iniciais, quanto à doação de órgãos para pacientes alcoólatras, não doadores, usuários de drogas ilícitas, estrangeiros e criminosos. CONCLUSÃO: Este trabalho demonstrou grande interesse e atitude positiva dos estudantes de medicina sobre doação e transplante de órgãos, embora a maioria tenha declarado conhecimento deficiente sobre o tema. Observamos também atitude negativa dos estudantes do quarto, quinto e sexto ano médico em relação à doação para alcoólatras, não doadores, usuários de drogas ilícitas, estrangeiros e criminosos.We analyzed the opinion and understanding of medical students about organ donation and transplantation. METHODS: 347 students voluntarily completed a questionnaire with 17

  7. Localization and separation of acoustic sources by using a 2.5-dimensional circular microphone array.

    Science.gov (United States)

    Bai, Mingsian R; Lai, Chang-Sheng; Wu, Po-Chen

    2017-07-01

    Circular microphone arrays (CMAs) are sufficient in many immersive audio applications because azimuthal angles of sources are considered more important than the elevation angles in those occasions. However, the fact that CMAs do not resolve the elevation angle well can be a limitation for some applications which involves three-dimensional sound images. This paper proposes a 2.5-dimensional (2.5-D) CMA comprised of a CMA and a vertical logarithmic-spacing linear array (LLA) on the top. In the localization stage, two delay-and-sum beamformers are applied to the CMA and the LLA, respectively. The direction of arrival (DOA) is estimated from the product of two array output signals. In the separation stage, Tikhonov regularization and convex optimization are employed to extract the source amplitudes on the basis of the estimated DOA. The extracted signals from two arrays are further processed by the normalized least-mean-square algorithm with the internal iteration to yield the source signal with improved quality. To validate the 2.5-D CMA experimentally, a three-dimensionally printed circular array comprised of a 24-element CMA and an eight-element LLA is constructed. Objective perceptual evaluation of speech quality test and a subjective listening test are also undertaken.

  8. Maternidade desnaturada: uma análise da barriga de aluguel e da doação de óvulos "Denatured" motherhood: an analysis of surrogate gestational motherhood and egg donation

    OpenAIRE

    Naara Luna

    2002-01-01

    O artigo discute representações sociais de duas práticas decorrentes das novas tecnologias reprodutivas ou reprodução assistida. Na fertilização in vitro, o procedimento de transferência do óvulo fertilizado de uma mulher para outra separa a maternidade genética da gestacional. Isto se traduz em duas práticas sociais: a doação de óvulos, em que a gestante é designada à mãe, e a maternidade gestacional substituta ("barriga de aluguel"), em que a mãe é a fornecedora do óvulo ou idealizadora da ...

  9. Maternidade desnaturada: uma análise da barriga de aluguel e da doação de óvulos "Denatured" motherhood: an analysis of surrogate gestational motherhood and egg donation

    Directory of Open Access Journals (Sweden)

    Naara Luna

    2002-01-01

    Full Text Available O artigo discute representações sociais de duas práticas decorrentes das novas tecnologias reprodutivas ou reprodução assistida. Na fertilização in vitro, o procedimento de transferência do óvulo fertilizado de uma mulher para outra separa a maternidade genética da gestacional. Isto se traduz em duas práticas sociais: a doação de óvulos, em que a gestante é designada à mãe, e a maternidade gestacional substituta ("barriga de aluguel", em que a mãe é a fornecedora do óvulo ou idealizadora da gravidez. O foco é a análise dessas representações no discurso jurídico e em matérias da grande imprensa brasileira, além do exame de etnografias sobre doação de óvulo e maternidade substituta. A oposição entre Natureza e Cultura é uma chave para compreender a recepção distinta dessas práticas.This article discusses social representations of two practices related to the new reproductive technologies or assisted reproduction techniques. During in vitro fertilization, the transfer procedure of a woman's fertilized egg to another woman separates genetic motherhood from gestational motherhood. Two practices relate to that: in egg donation the pregnant woman is considered the mother, while in surrogate gestational motherhood the mother is the egg donor or the woman who planned the gestation. The focus is in the analysis of the representations of egg donation and surrogate motherhood in juridical discourse and in texts from the Brazilian press, considering also ethnographic articles. The opposition between Nature and Culture is a key for understanding the different reception of these practices.

  10. Application of asymptotic expansions for maximum likelihood estimators' errors to gravitational waves from inspiraling binary systems: The network case

    International Nuclear Information System (INIS)

    Vitale, Salvatore; Zanolin, Michele

    2011-01-01

    This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by nonspinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for six different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one sigma angular resolution is below 2 square degrees increases about 3 times when transitioning from the Hanford (USA), Livingston (USA) and Cascina (Italy) network to a network made of five interferometers (while keeping the network SNR fixed). The technique adopted here is an asymptotic expansion of the uncertainties in inverse powers of the SNR where the first order is the inverse Fisher information matrix. We show that the commonly employed approach of using a simplified parameter spaces and only the Fisher information matrix can largely underestimate the uncertainties (the combined effect would lead to a factor 7 for the one sigma sky uncertainty in square degrees at a network SNR of 15).

  11. Parameter Estimation

    DEFF Research Database (Denmark)

    Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian

    2011-01-01

    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....

  12. Opinião e conhecimento da população da cidade de curitiba sobre doação e transplante de órgãos Opinion and knowledge of the population of a brazilian city about organ donation and transplantation

    Directory of Open Access Journals (Sweden)

    Julio Cezar Uili Coelho

    2007-10-01

    Full Text Available OBJETIVOS: Determinar a opinião e o conhecimento, de uma amostra da população da cidade de Curitiba, sobre doação e transplante de órgãos. MÉTODOS: A opinião e o conhecimento sobre doação e transplante de órgãos de mil pessoas, com idade superior a 18 anos, foram determinados através de um questionário de 20 perguntas. Os entrevistados avaliados tinham uma distribuição similar em idade, sexo e padrão socioeconômico, e escolaridade à população brasileira, determinada pelo IBGE. RESULTADOS: A maioria dos entrevistados (87,8% era favorável à doação de órgãos. Não houve diferença na percentagem da população favorável à doação de órgãos com a relação a sexo, estado civil, religião e rendimentos. Os principais motivos para serem favoráveis à doação de órgãos foram para salvar vida, ajudar o próximo e doar vida. Os principais motivos para não serem favoráveis à doação foram falta de confiança na medicina ou no sistema de captação e distribuição de órgãos, por haver comércio de órgãos e temor de mutilação do corpo. A maioria dos entrevistados respondeu que os ricos tinham mais chances de serem transplantados do que os pobres, que existe venda de órgãos no Brasil e que existe possibilidade de erro no diagnóstico de morte encefálica estabelecido pelo médico. CONCLUSÃO: A maioria da população deste estudo é favorável à doação de órgãos e tem um bom conhecimento sobre doação e transplante de órgãos. A maioria demonstrou não confiar no sistema de distribuição de órgãos e no diagnóstico de morte encefálica.OBJECTIVE: To determine the opinion and knowledge of the population of Curitiba about organ donation and transplantation. METHODS: The opinion and knowledge about organ donation and transplantation of 1,000 subjects over 18 years of age were determined. The subjects responded to a questionnaire of 20 queries. Respondents had age, gender, social-economic, and education

  13. Investigating the use of multi-point coupling for single-sensor bearing estimation in one direction

    Science.gov (United States)

    Woolard, Americo G.; Phoenix, Austin A.; Tarazaga, Pablo A.

    2018-04-01

    Bearing estimation of radially propagating symmetric waves in solid structures typically requires a minimum of two sensors. As a test specimen, this research investigates the use of multi-point coupling to provide directional inference using a single-sensor. By this provision, the number of sensors required for localization can be reduced. A finite-element model of a beam is constructed with a symmetrically placed bipod that has asymmetric joint-stiffness properties. Impulse loading is applied at different points along the beam, and measurements are taken from the apex of the bipod. A technique is developed to determine the direction-of-arrival of the propagating wave. The accuracy when using the bipod with the developed technique is compared against results gathered without the bipod and measuring from an asymmetric location along the beam. The results show 92% accuracy when the bipod is used, compared to 75% when measuring without the bipod from an asymmetric location. A geometry investigation finds the best accuracy results when one leg of the bipod has a low stiffness and a large diameter relative to the other leg.

  14. Conhecimento e atitude da população do Hospital São Paulo sobre doação de córneas Knowledge and attitude of the general population regarding corneal transplantation

    Directory of Open Access Journals (Sweden)

    Adriana Maria Rodrigues

    2002-12-01

    Full Text Available Objetivo: O presente estudo teve por objetivo analisar o conhecimento e atitude da população em geral sobre transplante de córneas e, desta forma, tentar identificar as principais deficiências e barreiras para o aumento do número de doações. Métodos: Foi aplicado questionário a 321 pessoas que transitavam pelo Hospital São Paulo, centro de referência da cidade de São Paulo. Resultados: Do total de pessoas questionadas, 79,4% diziam-se doadoras de córneas e 20,6%, não. O principal motivo encontrado da não-doação foi o medo referente à venda de órgão e incerteza de receber o tratamento adequado à medida que se considera um doador em potencial. Foi encontrada uma diferença estatisticamente significante entre o conhecimento sobre transplante de córnea e o fato de dizer-se doador. Conclusão: Concluímos que melhoria na informação da população em geral é fator decisivo para aumentar a demanda de doadores.Purpose: To analyze the knowledge and attitude of the general population in order to identify the main deficiencies and to suggest measures to increase the number of cornea donations by the general population. Methods: Study through questionnaire polls answered by 321 people at the São Paulo Hospital. Results: Among the general population, 79.4% said to be cornea donors. The reason for the other 20.6% not to be donors was fear of trade of organ and not to receive proper treatment by the medical staff for being a potential donor. There was a statistically significant difference of knowledge about transplantation between those who said to be donors and those who did not. Conclusion: The authors concluded that better information on corneal transplantation for the general population would be of great help in increasing the number of cornea donations.

  15. Development of SAP-DoA techniques for GPR data processing within COST Action TU1208

    Science.gov (United States)

    Meschino, Simone; Pajewski, Lara; Marciniak, Marian

    2016-04-01

    This work focuses on the use of Sub-Array Processing (SAP) and Direction of Arrival (DoA) approaches for the processing of Ground-Penetrating Radar data, with the purpose of locating metal scatterers embedded in concrete or buried in the ground. Research activities have been carried out during two Short-Term Scientific Missions (STSMs) funded by the COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" in May 2015 and January 2016. In applications involving smart antennas and in the presence of several transmitters operating simultaneously, it is important for a receiving array to be able to estimate the Direction of Arrival (DoA) of the incoming signals, in order to decipher how many emitters are present and predict their positions. A number of methods have been devised for DoA estimation: the MUltiple SIgnal Classification (MUSIC) and Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) are amongst the most popular ones [1]. In the scenario considered by us, the electromagnetic sources are the currents induced on metal elements embedded in concrete or buried in the ground. GPR radargrams are processed, to estimate the DoAs of the electric field back-scattered by the sought targets. In order to work in near-field conditions, a sub-array processing (SAP) approach is adopted: the radargram is partitioned in sub-radargrams composed of few A-scans each, the dominant DoA is predicted for each sub-radargram. The estimated angles are triangulated, obtaining a set of crossings with intersections condensed around object locations. This pattern is filtered, in order to remove a noisy background of unwanted crossings, and is processed by applying the statistical procedure described in [2]. We tested our approach on synthetic GPR radargrams, obtained by using the freeware simulator gprMax implementing the Finite-Difference Time-Domain method [3]. In particular, we worked with

  16. A doação da biblioteca João do Rio ao Real Gabinete Português de Leitura: aspectos de uma história pouco conhecida

    Directory of Open Access Journals (Sweden)

    Fabiano Cataldo de Azevedo

    Full Text Available Expõe resultado de investigação acerca da origem da Biblioteca de Paulo Barreto (João do Rio no Real Gabinete Português de Leitura. Como subsídios documentais, utilizamos vários documentos pouco conhecidos pela comunidade científica. A abordagem se insere no âmbito de Formação e Desenvolvimento de Coleções, uma vez que conhecer a história das coleções que compõem uma biblioteca favorece a compreensão de sua história. Objetiva oferecer elementos para estudos acerca do escritor e jornalista. Reconstrói e relata todo o processo de doação e recepção dos livros do escritor fluminense, utilizando fontes manuscritas e impressas. Apresenta amostragem de autores presentes na coleção, analisa a forma de organização do acervo e infere que a disposição adotada atualmente é a mesma privilegiada por seu primitivo possuidor.

  17. Compressive Sound Speed Profile Inversion Using Beamforming Results

    OpenAIRE

    Youngmin Choo; Woojae Seong

    2018-01-01

    Sound speed profile (SSP) significantly affects acoustic propagation in the ocean. In this work, the SSP is inverted using compressive sensing (CS) combined with beamforming to indicate the direction of arrivals (DOAs). The travel times and the positions of the arrivals can be approximately linearized using their Taylor expansion with the shape function coefficients that parameterize the SSP. The linear relation between the travel times/positions and the shape function coefficients enables CS...

  18. Acquisition of Cooperative Small Unmanned Aerial Systems for Advancing Man Machine Interface Research

    Science.gov (United States)

    2016-08-24

    Airborne Cross Runway Departure/Landing Scenario Figure 7 Illustration of a participant looking at the 10Hz or 15Hz flickering visual stimulus in a...Figure 5 An illustration using a formation of UAVs for Direction of Arrival (DOA) mitigation of spoofing signals Spoofer Antenna array based on a...this project is to research and develop robust and jamming-resistant receivers including advanced interference mitigation algorithms and network

  19. A Space-Time Signal Decomposition Algorithm for Downlink MIMO DS-CDMA Receivers

    Science.gov (United States)

    Wang, Yung-Yi; Fang, Wen-Hsien; Chen, Jiunn-Tsair

    We propose a dimension reduction algorithm for the receiver of the downlink of direct-sequence code-division multiple access (DS-CDMA) systems in which both the transmitters and the receivers employ antenna arrays of multiple elements. To estimate the high order channel parameters, we develop a layered architecture using dimension-reduced parameter estimation algorithms to estimate the frequency-selective multipath channels. In the proposed architecture, to exploit the space-time geometric characteristics of multipath channels, spatial beamformers and constrained (or unconstrained) temporal filters are adopted for clustered-multipath grouping and path isolation. In conjunction with the multiple access interference (MAI) suppression techniques, the proposed architecture jointly estimates the direction of arrivals, propagation delays, and fading amplitudes of the downlink fading multipaths. With the outputs of the proposed architecture, the signals of interest can then be naturally detected by using path-wise maximum ratio combining. Compared to the traditional techniques, such as the Joint-Angle-and-Delay-Estimation (JADE) algorithm for DOA-delay joint estimation and the space-time minimum mean square error (ST-MMSE) algorithm for signal detection, computer simulations show that the proposed algorithm substantially mitigate the computational complexity at the expense of only slight performance degradation.

  20. Processo de doação de órgãos: percepção de familiares de doadores cadáveres Proceso de donación de órganos: percepción de familiares de donantes cadáveres Organ donation process: perception by relatives of cadaverous donors

    Directory of Open Access Journals (Sweden)

    Marcelo José dos Santos

    2005-06-01

    Full Text Available Este estudo teve como objetivo desvelar a percepção de familiares de doadores cadáveres sobre o processo de doação de órgãos para transplante. Foi realizada uma pesquisa qualitativa, na vertente fenomenológica, segundo a modalidade "estrutura do fenômeno situado". As proposições que emergiram revelaram que, para os familiares de doadores cadáveres de órgãos, o processo de doação inicia-se com a internação do paciente e termina somente com o sepultamento do mesmo, sendo considerado burocrático, demorado, desgastante e cansativo. A situação vivenciada é sofrida e estressante, mas não há arrependimento quanto à doação dos órgãos, pois, embora a dor da perda não termine, a atitude da doação conforta e traz satisfação.La finalidad de este estudio fue desvelar la percepción de familiares de donantes cadáveres sobre el proceso de donación de órganos para trasplante. Fue realizada una investigación cualitativa del tipo fenomenológico, según la modalidad de "estructura del fenómeno situado". Las proposiciones que emergieron revelaron que, para los familiares de donantes cadáveres de órganos, el proceso de donación se inicia con la internación del paciente y termina solamente con el sepelio del mismo, siendo considerado burocrático, tardado, desgastante y agotador. La situación vivenciada es sufrida y estresante, pero no hay arrepentimiento respecto a la donación de los órganos pues, aunque el dolor de la pérdida no termine, la actitud de la donación conforta y trae satisfacción.This study aimed to disclose how relatives of cadaverous donors perceive the organ donation process for transplantation. A phenomenological, qualitative research was carried out on the basis of the "situated-phenomenon structure". The statements revealed that, for the relatives of the donors, the process of donation begins with the patients' hospital admission and only ends when they are buried. Furthermore, it is considered

  1. Recusa de doação de órgãos e tecidos para transplante relatados por familiares de potenciais doadores Negación de donación de órganos y tejidos para transplante relatados por familiares de potenciales donadores Reasons for the family members' refusal to donate organ and tissue for transplant

    Directory of Open Access Journals (Sweden)

    Edvaldo Leal de Moraes

    2009-01-01

    Full Text Available OBJETIVO: Conhecer a percepção de familiares de potenciais doadores sobre os motivos de recusa para doação de órgãos e tecidos para transplante. MÉTODOS: Trata-se de uma pesquisa qualitativa, na vertente fenomenológica, modalidade "estrutura do fenômeno situado". Participaram do estudo oito familiares que recusaram a doação dos órgãos e tecidos. RESULTADOS: Após análise das entrevistas, foram revelados dez motivos de recusa, considerados pelos familiares. CONSIDERAÇÕES FINAIS: As proposições que emergiram revelaram que os motivos de recusa familiar para doação de órgãos e tecidos estão relacionados à crença, valores e inadequações no processo de doação e transplante.OBJETIVO: Conocer la percepción de familiares de potenciales donadores sobre los motivos de su negación para la donación de órganos y tejidos para transplante. MÉTODOS: Se trata de una investigación cualitativa, en la vertiente fenomenológica, modalidad "estructura del fenómeno situado". Participaron del estudio ocho familiares que se negaron a la donación de órganos y tejidos. RESULTADOS: Después del análisis de las entrevistas se revelaron diez motivos de negación expuestos por los familiares. CONSIDERACIONES FINALES: Las proposiciones que emergieron revelaron que los motivos de la negativa familiar para la donación de órganos y tejidos están relacionados a la creencia, valores e inadecuaciones en el proceso de donación y transplante.OBJECTIVE: To understand the perception of family members of potential donors in regard to their reasons for refusal to donate organ and tissue for transplant. METHODS: A qualitative phenomenological approach was used to conduct this study. A sample of eight family members who refused to donate organ and tissue for transplant participated in the study. RESULTS: Participants reported ten reasons for refusal to donate organ and tissue for transplant. FINAL CONSIDERATIONS: Reasons for the family members

  2. Bearing and Range Estimation Algorithm for Buried Object in Underwater Acoustics

    Directory of Open Access Journals (Sweden)

    Dong Han

    2009-01-01

    (DOA of objects and objects-sensors distances, is used in MUSIC algorithm instead of classical model. The influence of the depth of buried objects is discussed. Finally, the numerical results are given in the case of buried cylindrical shells.

  3. Estimating Utility

    DEFF Research Database (Denmark)

    Arndt, Channing; Simler, Kenneth R.

    2010-01-01

    A fundamental premise of absolute poverty lines is that they represent the same level of utility through time and space. Disturbingly, a series of recent studies in middle- and low-income economies show that even carefully derived poverty lines rarely satisfy this premise. This article proposes a......, with the current approach tending to systematically overestimate (underestimate) poverty in urban (rural) zones.......A fundamental premise of absolute poverty lines is that they represent the same level of utility through time and space. Disturbingly, a series of recent studies in middle- and low-income economies show that even carefully derived poverty lines rarely satisfy this premise. This article proposes...... an information-theoretic approach to estimating cost-of-basic-needs (CBN) poverty lines that are utility consistent. Applications to date illustrate that utility-consistent poverty measurements derived from the proposed approach and those derived from current CBN best practices often differ substantially...

  4. Preliminary Assessment About Genetic Diversity, The Stability Of Potential Mutants From Two Varieties Of Chrysanthemum Morifolium Ramat. (Bronze DOA And Purple Farm) Via Gamma Irradiation

    International Nuclear Information System (INIS)

    Nguyen Tuong Mien; Le Ngoc Trieu; Le Tien Thanh; Pham Van Nhi; Huynh Thi Trung

    2014-01-01

    The objects of radiation breeding were chosen, collected and in vitro propagated. The suitable modalities for acute and chronic irradiation the materials were determined. Two acute and one chronic irradiation series were executed. Thus, the irradiated materials were achieved to screening for the mutants. In this study, on farm, through screening 18 phenotypic mutants of both chrysanthemums were recorded and collected including 6 potential mutants that selected for next research based on their phenotypic differences to the originals, their aesthetic and low mosaic. These 6 potential mutants together with their original varieties were micro-propagated to induce the potential mutant lines for estimation on farm of mutant characteristic segregation rates. Six potential mutant lines of E2a, E2c, E28, E29, I7, I8 are morphologically and genetically different to their original varieties, possess the identification markers and aestheticism. They were morphologically stable on farm through 3 series of growing on farm at M1V3, M1V5 and M1V7 generations. In the genetic respect, they possessed the high stabilities through in vitro generations. All of these criteria show that, these mutant lines were already to be registered as temporary cultivars/varieties. (author)

  5. Retrieval of stratospheric and tropospheric BrO profiles and columns using ground-based zenith-sky DOAS observations at Harestua, 60° N

    Directory of Open Access Journals (Sweden)

    J. A. Pyle

    2007-09-01

    Full Text Available A profiling algorithm based on the optimal estimation method is applied to ground-based zenith-sky UV-visible measurements from Harestua, Southern Norway (60° N, 11° E in order to retrieve BrO vertical profiles. The sensitivity of the zenith-sky observations to the tropospheric BrO detection is increased by using for the spectral analysis a fixed reference spectrum corresponding to clear-sky noon summer conditions. The information content and retrieval errors are characterized and it is shown that the retrieved stratospheric profiles and total columns are consistent with correlative balloon and satellite observations, respectively. Tropospheric BrO columns are derived from profiles retrieved at 80° solar zenith angle during sunrise and sunset for the 2000–2006 period. They show a marked seasonality with mean column value ranging from 1.52±0.62×1013 molec/cm² in late winter/early spring to 0.92±0.38×1013 molec/cm² in summer, which corresponds to 1.0±0.4 and 0.6±0.2 pptv, respectively, if we assume that BrO is uniformly mixed in the troposphere. These column values are also consistent with previous estimates made from balloon, satellite, and other ground-based observations. Daytime (10:30 LT tropospheric BrO columns are compared to the p-TOMCAT 3-D tropospheric chemical transport model (CTM for the 2002–2003 period. p-TOMCAT shows a good agreement with the retrieved columns except in late winter/early spring where an underestimation by the model is obtained. This finding could be explained by the non-inclusion of sea-ice bromine sources in the current version of p-TOMCAT. Therefore the model cannot reproduce the possible transport of air-masses with enhanced BrO concentration due to bromine explosion events from the polar region to Harestua. The daytime stratospheric BrO columns are compared to the SLIMCAT stratospheric 3-D-CTM. The model run used in this study, which assumes 21.2 pptv for the Bry loading (15 pptv for long

  6. Doação e adoção como políticas para salvar os embriões humanos excedentes e congelados Donation and adoption as ways of saving excess frozen human embryos

    Directory of Open Access Journals (Sweden)

    Gerson Odilon Pereira

    2010-12-01

    Full Text Available Este artigo trata da divergência científica existente com relação à sobra de embriões congelados, particularmente entre a biologia, a religião, o direito e a bioética, e focando especialmente nos meios e nas formas com que cada uma dessas ciências caracteriza o início da vida. É objetivo dos autores, ainda, fornecer alternativas para a proteção do embrião humano, como a adoção por casais ou apenas por mulheres que, por razões médicas, não podem ser fertilizadas, mas que podem gestar. Em se tratando de Brasil, os autores concluem ser legal e legítimo a doação e a adoção de embrião humano para fertilização, desde que sejam considerados o princípio da dignidade da pessoa humana e mantido o sigilo sobre a identidade dos doadores de gametas, cujos dados devem permanecer registrados de forma permanente no centro onde ocorreu a fertilização.This article deals with the existing scientific divergence with regard to the surplus of frozen embryos, especially between biology, religion, the law and bioethics, with a specific focus on the ways in which each of these areas determines the onset of life. The aim of the authors is to suggest alternatives that protect the human embryo, such as adoption by couples or by single women, who, for medical reasons, are infertile, but are capable of bearing a child. In the case of Brazil, the authors conclude that it is legal and legitimate to donate and adopt human embryos for fertilization, so long as the principle of human dignity is upheld and confidentiality maintained regarding the identity of the donors of the gametes, whose data should remain on file permanently at the center where fertilization occurred.

  7. Novas tecnologias reprodutivas: doação de óvulos. O que pode ser novo nesse campo? New reproductive technologies: oocyte donation. What could be new in this field?

    Directory of Open Access Journals (Sweden)

    Marilena V. Corrêa

    2000-09-01

    Full Text Available Este artigo discute as "novas" tecnologias reprodutivas. Através da interrogação dessa adjetivação, são analisadas estratégias e contradições que mantêm como novo esse conjunto de técnicas e experiências médicas iniciadas há mais de duas décadas e que encontraram ampla difusão no mercado de serviço médicos. A presença, na mídia, da temática dos bebês de proveta e, sobretudo, de seus desdobramentos em termos da intervenção sobre células germinativas e sobre embriões humanos, ajuda a conferir o caráter de permanente novidade a tudo o que cerca as tecnologias reprodutivas e as intervenções genéticas por ela possibilitadas. Apesar de, sem dúvida, encontrarmo-nos diante de um processo aberto e em plena inovação, os efeitos sociais e simbólicos no plano da maternidade, paternidade e filiação são ainda pouco sentidos e discutidos. Para ilustrar tais contradições é focalizado o caso da doação de óvulos. Este evidencia a necessidade de serem buscadas novas perspectivas em termos do controle social da difusão das tecnologias reprodutivas entre nós.This article discusses the so-called "new" reproductive technologies. The author analyzes and challenges this adjective, since for over two decades this group of medical techniques and experiments has been widely disseminated in the medical market. The media's coverage of test tube babies, and especially developments in intervention on human germ cells and embryos, help challenge the supposed permanent novelty of everything surrounding reproductive technologies and genetic interventions. Society is doubtless experiencing an open process in full innovation, but the social and symbolic effects on planning maternity, paternity, and filiation are still not well perceived or discussed. To illustrate such contradictions, the article focuses on the case of oocyte donation, highlighting the need for new perspectives in terms of social control over the dissemination of

  8. Detection of Buried Objects by Means of a SAP Technique: Comparing MUSIC- and SVR-Based Approaches

    Science.gov (United States)

    Meschino, S.; Pajewski, L.; Pastorino, M.; Randazzo, A.; Schettini, G.

    2012-04-01

    This work is focused on the application of a Sub-Array Processing (SAP) technique to the detection of metallic cylindrical objects embedded in a dielectric half-space. The identification of buried cables, pipes, conduits, and other cylindrical utilities, is an important problem that has been extensively studied in the last years. Most commonly used approaches are based on the use of electromagnetic sensing: a set of antennas illuminates the ground and the collected echo is analyzed in order to extract information about the scenario and to localize the sought objects [1]. In a SAP approach, algorithms for the estimation of Directions of Arrival (DOAs) are employed [2]: they assume that the sources (in this paper, currents induced on buried targets) are in the far-field region of the receiving array, so that the received wavefront can be considered as planar, and the main angular direction of the field can be estimated. However, in electromagnetic sensing of buried objects, the scatterers are usually quite near to the antennas. Nevertheless, by dividing the whole receiving array in a suitable number of sub-arrays, and by finding a dominant DOA for each one, it is possible to localize objects that are in the far-field of the sub-array, although being in the near-field of the array. The DOAs found by the sub-arrays can be triangulated, obtaining a set of crossings with intersections condensed around object locations. In this work, the performances of two different DOA algorithms are compared. In particular, a MUltiple SIgnal Classification (MUSIC)-type method [3] and Support Vector Regression (SVR) based approach [4] are employed. The results of a Cylindrical-Wave Approach forward solver are used as input data of the detection procedure [5]. To process the crossing pattern, the region of interest is divided in small windows, and a Poisson model is adopted for the statistical distribution of intersections in the windows. Hypothesis testing procedures are used (imposing

  9. Doação de órgãos e tecidos: relação com o corpo em nossa sociedade Donación de órganos y tejidos: relación con el cuerpo en nuestra sociedad Organ and tissues donation: relation with the body in our society

    Directory of Open Access Journals (Sweden)

    Bartira De Aguiar Roza

    2010-06-01

    Full Text Available Este estudo, de revisão bibliográfica, objetivou tecer considerações teóricas sobre doação de órgãos e tecidos e sua relação com o corpo em nossa sociedade. O aumento da taxa de doação depende de um olhar ampliado além das questões técnicas do processo de doação de órgãos e tecidos. Vários países, com larga experiência temporal e, que trabalham sistematicamente nesse processo, incorporaram a abordagem social e a perspectiva ética, baseadas no voluntarismo das famílias e no respeito ao direito de autonomia dos potenciais doadores. O acompanhamento do corpo, pós-doação, solicitado pelas famílias, representa o início do luto pela morte de um parente, parte da prática de ritual fúnebre cultuada em nossa sociedade. As ações que asseguram uma sequência ético-legal, definida na legislação dos transplantes, pressupõem compromisso com a qualidade e segurança do processo de doação de órgãos e tecidos, que deve ser rigorosamente perseguida pelos profissionais que trabalham na área. Espera-se, assim, que essas atitudes construam uma cultura positiva sobre a doação no país, contribuindo, a longo prazo, para o aumento nas taxas de doação.Se trata de un estudio de revisión de literatura dirigida a elaborar consideraciones teóricas sobre la donación de órganos y tejidos y su relación con el cuerpo en nuestra sociedad. El aumento de la tasa de donación depende de una visión que va más allá de las cuestiones técnicas en el proceso de la donación de órganos y tejidos. Varios países con gran tiempo de experiencia, trabajando sistemáticamente en este proceso con un enfoque que incorpora el punto de vista social y ético, basado en voluntarios y respetando en las familias el derecho a la autonomía de los posibles donantes. El acompañamiento del cuerpo, después de la donación, generalmente solicitado por la familia, representa el comienzo del luto por la muerte de un pariente, lo que hace parte del

  10. Impacto do marketing dos processos de divulgação nas doações de córneas a um banco de tecidos oculares humanos e avaliação do perfil socioeconômico de seus doadores Marketing role of corneal graft tissue donation to an eye bank and donors' socioeconomic profile

    Directory of Open Access Journals (Sweden)

    Roberta Jansen de Mello Farias

    2008-02-01

    Full Text Available A ceratoplastia penetrante tem-se tornado a forma de transplante de maior emprego e sucesso nos Estados Unidos. No Brasil, ela teve início em 1964. OBJETIVOS: Avaliar o impacto no número de doações de córneas ao Banco de Olhos de Sorocaba a partir da implementação de um sistema de captação de córneas e traçar o perfil socioeconômico dos doadores de córneas no Banco de Olhos de Sorocaba (BOS. MÉTODOS: Foi realizado um estudo retrospectivo do volume de doações ao BOS do início de sua criação (1971 após a realização de uma intensa política de marketing interno e externo. A análise do perfil socioeconômico dos doadores de córneas foi avaliada, prospectivamente, por meio de cartas com questionário, enviadas às referidas famílias em um dado mês. RESULTADOS: O BOS iniciou o trabalho em 1971 com a divulgação da necessidade de doação de órgãos sendo feita com a utilização de palestras em igrejas, shoppings e reuniões de comunidade, programas de rádio, programas de televisão, etc. Na década de 1970 e no início da década de 1980, o número de córneas captadas oscilava entre 1 a 2/mês. Entre 1984 e 1989, houve formação de uma equipe de abordagem com treinamento de 60 horas anuais atuante em funerárias, e a partir de 2000, estas também começaram a agir em hospitais. Em 1984 foram captadas somente 260 córneas. Este número foi aumentando gradativamente, até chegar em 2004 com o total de 2.778 córneas doadas. Os questionários aplicados foram respondidos pelas famílias de 76 dos 93 doadores, dando-nos uma taxa de resposta de 81,7%. A idade dos doadores foi em média de 65,1 ± 14,7 anos, 42 (55,3% eram do sexo masculino. O nível de educação da família dos doadores foi fator importante na doação de órgãos, uma vez que 36,8% apresentavam ensino médio completo e 34,2% apresentavam ensino superior completo. A grande maioria, 63 (82,9% das 76 doações (152 córneas decorreu do esforço da equipe de

  11. Variance estimation for generalized Cavalieri estimators

    OpenAIRE

    Johanna Ziegel; Eva B. Vedel Jensen; Karl-Anton Dorph-Petersen

    2011-01-01

    The precision of stereological estimators based on systematic sampling is of great practical importance. This paper presents methods of data-based variance estimation for generalized Cavalieri estimators where errors in sampling positions may occur. Variance estimators are derived under perturbed systematic sampling, systematic sampling with cumulative errors and systematic sampling with random dropouts. Copyright 2011, Oxford University Press.

  12. Doação e transplante de órgãos: produção científica da enfermagem brasileira Donación y transplante de órganos: producción científica de la enfermería brasileña Organ donation and transplantation: Brazilian nursing publications

    Directory of Open Access Journals (Sweden)

    Emilia Aparecida Cicolo

    2010-04-01

    Full Text Available Estudo bibliográfico cujos objetivos foram identificar e caracterizar as produções científicas de enfermagem em doação e transplante de órgãos, no período de 1997 a 2007. Realizou-se busca das publicações nacionais nas bases de dados LILACS, MEDLINE, BDENF, PERIENF E DEDALUS, com as palavras-chave: "enfermagem e transplante" e "enfermagem e doação". Os 30 artigos encontrados foram analisados sob diversos aspectos, obtendo-se como resultados principais: a maioria originou-se do Sudeste, teve abordagem qualitativa, foi da autoria de enfermeiros assistenciais e abordou o tema transplante, especialmente renal e hepático. Conclui-se que se faz necessário um maior número de estudos científicos, desenvolvidos pela enfermagem de todo o país, sobre os diversos aspectos da doação e transplante de órgãos.Estudio bibliográfico cuyos objetivos fueron identificar y caracterizar las producciones científicas de enfermería sobre donación y trasplante de órganos, en el período de 1997 a 2007. Se buscaron publicaciones en las bases de datos LILACS, MEDLINE, BDENF, PERIENF Y DEDALUS, con las palabras clave: "enfermería y trasplante" y "enfermería y donación", identificándose 30 artículos. Los resultados encontrados mostraron que los trabajos se originaron principalmente en el Sudeste, el enfoque cualitativo fue el más utilizado, los enfermeros fueron los autores principales y los temas utilizados con más frecuencia fueron el trasplante renal y el hepático. Se concluye que es necesario más publicaciones de enfermería brasileña sobre donación y trasplante de órganos.The objectives of this bibliographic study were to identify and to characterize nursing scientific productions of organ donation and transplantation since 1997 to 2007. The LILACS, MEDLINE, BDENF, PERIENF AND DEDALUS databases were searched using the following keywords: "nursing and transplantation" and "nursing and donation", identifying 30 articles. The results

  13. Breast milk donation and social support: reports of women donors Donación de leche humana y apoyo social: relatos de mujeres donadoras Doação de leite humano e apoio social: relatos de mulheres doadoras

    Directory of Open Access Journals (Sweden)

    Lucienne Christine Estevez de Alencar

    2010-06-01

    . Sugerencias más frecuentes para mejorar el apoyo institucional fueron mayor atención y apoyo de los bancos de leche a las donadoras. El estudio podrá servir de estímulo para implementación de estrategias técnicas y políticas que favorezcan esa práctica.O estudo objetivou caracterizar o comportamento de doação de leite humano e descrever o apoio social informal e institucional, segundo relatos de mulheres doadoras. Trata-se de estudo exploratório, descritivo, de corte transversal, com entrevista domiciliar baseada em roteiros estruturado e semiestruturado. Participaram 36 mulheres cadastradas em dois bancos de leite humano da rede pública de saúde do Distrito Federal. Foram realizadas análises estatísticas descritivas de dados quantitativos e categorial de conteúdo dos dados qualitativos. Categorias de motivos que mais influenciaram na frequência da ordenha: alimentação, disponibilidade de tempo, emoções negativas e ingestão de líquidos. A ordenha manual foi referida como técnica predominante. O uso da “conchinha” foi citado por quase um terço das doadoras. Sugestões mais frequentes para melhorar o apoio institucional foram maior atenção e apoio dos bancos de leite às doadoras. O estudo poderá servir de estímulo para implementação de estratégias técnicas e políticas que favoreçam essa prática.

  14. Crenças que influenciam adolescentes na doação de órgãos Creencias que influyen en los adolescentes para la donación de órganos Beliefs that influence adolescents in organ donations

    Directory of Open Access Journals (Sweden)

    Márcia Wanderley de Moraes

    2006-12-01

    Full Text Available Foram objetivos do estudo identificar conhecimento, crenças comportamentais e normativas de estudantes de nível médio sobre transplante e doação de órgãos, à luz da Teoria da Ação Racional (TRA, em duas escolas da rede pública do município de São Paulo. A amostra foi constituída por 94 alunos que responderam um questionário baseado nos pressupostos da TRA e as respostas foram submetidas à análise estatística. O resultado mostra baixo conhecimento sobre doação de órgãos, pois 45,8% desconhecem o conceito de morte encefálica; 37,2% não sabem quando a morte ocorre e 70,3% não sabem quando uma pessoa se torna potencial doador. Foram evidenciadas dez crenças positivas relativas ao comportamento de ser doador de órgãos. Salientaram-se, também, sete crenças negativas sobre doação de órgãos. Foram evidenciadas oito crenças positivas e cinco crenças negativas relativas à doação de órgãos. Conclui-se ser necessário desenvolver estudos e implementar programas educativos de esclarecimento sobre o tema.Los objetivos del estudio fueron identificar el conocimiento, creencias de comportamiento y normativas de estudiantes de nivel medio respecto al transplante y donación de órganos, a la luz de la Teoría de la Acción Racional (TRA, en dos escuelas de la red pública del municipio de Sao Paulo. La muestra estuvo constituida por 94 alumnos que respondieron un cuestionario basado en las premisas de la TRA y las respuestas fueron sometidas al análisis estadístico. El resultado muestra bajo conocimiento sobre donación de órganos, pues el 45,8% desconoce el concepto de muerte encefálica; el 37,2% no sabe cuándo ocurre la muerte y el 70,3% no sabe cuándo una persona se torna en potencial donador. Fueron evidenciadas diez creencias positivas relativas al comportamiento de ser donador de órganos. Resaltaron, también, siete creencias negativas sobre donación de órganos. Se evidenciaron ocho creencias positivas y

  15. Bone Marrow Donation from the Perspective of Sibling Donors Donación de médula ósea en la perspectiva de hermanos donadores Doação de medula óssea na perspectiva de irmãos doadores

    Directory of Open Access Journals (Sweden)

    Érika Arantes de Oliveira-Cardoso

    2010-10-01

    del proceso de donación. Frente a lo encontrado, se recomienda que el equipo planifique estrategias de intervención que permitan atender las necesidades específicas de los donadores.Este estudo objetivou caracterizar o perfil sociodemográfico e descrever a percepção de irmãos doadores de medula óssea acerca da doação. Trata-se de estudo descritivo, exploratório e com recorte longitudinal. Participaram 20 doadores relacionados de medula óssea, com idade entre 18 e 42 anos (média=30,5 anos, dp=7,47. Foram utilizadas entrevistas, aplicadas antes e imediatamente após a doação. Foi realizada análise estatística descritiva dos dados sociodemográficos e análise de conteúdo categorial dos dados qualitativos. Nas entrevistas anteriores à doação, apareceram como eventos estressores o adoecimento e o tratamento do irmão e a responsabilidade de serem os doadores. No período posterior à doação, foi relatada ansiedade na véspera e no dia da doação, dor no dia seguinte, e o reconhecimento do apoio da equipe como elemento facilitador do processo de doação. Frente aos achados é interessante que a equipe possa traçar estratégias de intervenção que permitam atender as necessidades específicas dos doadores.

  16. Compressive Sound Speed Profile Inversion Using Beamforming Results

    Directory of Open Access Journals (Sweden)

    Youngmin Choo

    2018-05-01

    Full Text Available Sound speed profile (SSP significantly affects acoustic propagation in the ocean. In this work, the SSP is inverted using compressive sensing (CS combined with beamforming to indicate the direction of arrivals (DOAs. The travel times and the positions of the arrivals can be approximately linearized using their Taylor expansion with the shape function coefficients that parameterize the SSP. The linear relation between the travel times/positions and the shape function coefficients enables CS to reconstruct the SSP. The conventional objective function in CS is modified to simultaneously exploit the information from the travel times and positions. The SSP is estimated using CS with beamforming of ray arrivals in the SWellEx-96 experimental environment, and the performance is evaluated using the correlation coefficient and mean squared error (MSE between the true and recovered SSPs, respectively. Five hundred synthetic SSPs were generated by randomly choosing the SSP dictionary components, and more than 80 percent of all the cases have correlation coefficients over 0.7 and MSE along depth is insignificant except near the sea surface, which shows the validity of the proposed method.

  17. MISSION-ORIENTED SENSOR ARRAYS AND UAVs – A CASE STUDY ON ENVIRONMENTAL MONITORING

    Directory of Open Access Journals (Sweden)

    N. M. Figueira

    2015-08-01

    Full Text Available This paper presents a new concept of UAV mission design in geomatics, applied to the generation of thematic maps for a multitude of civilian and military applications. We discuss the architecture of Mission-Oriented Sensors Arrays (MOSA, proposed in Figueira et Al. (2013, aimed at splitting and decoupling the mission-oriented part of the system (non safety-critical hardware and software from the aircraft control systems (safety-critical. As a case study, we present an environmental monitoring application for the automatic generation of thematic maps to track gunshot activity in conservation areas. The MOSA modeled for this application integrates information from a thermal camera and an on-the-ground microphone array. The use of microphone arrays technology is of particular interest in this paper. These arrays allow estimation of the direction-of-arrival (DOA of the incoming sound waves. Information about events of interest is obtained by the fusion of the data provided by the microphone array, captured by the UAV, fused with information from the termal image processing. Preliminary results show the feasibility of the on-the-ground sound processing array and the simulation of the main processing module, to be embedded into an UAV in a future work. The main contributions of this paper are the proposed MOSA system, including concepts, models and architecture.

  18. Estressores vivenciados pelos familiares no processo de doação de órgãos e tecidos para transplante Estresores experimentados por los familiares en el proceso de donación de órganos y tejidos para transplante Stressor experienced by family members in the process of organ and tissue donation for transplant

    Directory of Open Access Journals (Sweden)

    Valdir Moreira Cinque

    2010-12-01

    Full Text Available O estudo propõe identificar os estressores vivenciados pelos familiares no processo de doação de órgãos, evidenciar o momento mais desgastante do processo e verificar a associação de variáveis com a experiência vivenciada pelos familiares. A amostra constituiu-se de 16 familiares que realizaram a doação por meio de uma Organização de Procura de Órgãos, na cidade de São Paulo, em 2007. Utilizou-se um instrumento estruturado com questões versando sobre a experiência e avaliação dos familiares no processo de doação. Os principais estressores foram: insatisfação com o atendimento (31,25%; receber a notícia da morte encefálica de forma intranquila (62,50%; e a demora para a liberação do corpo (62,50%, sendo este o momento mais desgastante do processo. Pelo coeficiente phi, verificou-se associação moderada entre as variáveis de interesse com a experiência da família. Conclui-se que o processo de doação é estressante para a família e que a assistência de enfermagem torna-se necessária em cada etapa da doação, oferecendo suporte para diminuir o sofrimento dos familiares.El estudio propone identificar los estresores experimentados por los familiares en el proceso de donación de órganos, evidenciar el momento más desgastante y verificar la asociación de variables con la experiencia afrontada por los familiares. La muestra se constituyó de 16 familiares que realizaron la donación en una Organización de Búsqueda de Órganos de la ciudad de São Paulo, en 2007. Se utilizó un instrumento estructurado con preguntas referidas a la experiencia y evaluación de los familiares en el proceso de donación. Lo principales estresores fueron: la insatisfacción con la atención (31,25%; recibir la noticia de muerte encefálica en forma impropia (62,50% y la demora para la liberación del cuerpo (62,50%, siendo éste el momento más desgastante. Por el coeficiente Phi, se verificó asociación moderada entre las

  19. Fatores associados à aptidão clínica para a doação de sangue: determinantes demográficos e socioeconômicos Factors associated to clinical aptness for blood donation: demographic and socioeconomic determinants

    Directory of Open Access Journals (Sweden)

    Stela Brener

    2008-04-01

    Full Text Available Crescimento significativo da preocupação com a segurança transfusional vem sendo observado nas últimas décadas, paralelo às alterações demográficas e sociais da população, além dos avanços técnico-científicos, que aumentam naturalmente a demanda por transfusões de sangue. Entretanto, apesar dos investimentos na captação de doadores, seu déficit continua sendo crônico. Este trabalho teve como objetivo comparar aspectos demográficos e socioeconômicos entre indivíduos aptos, inaptos temporários e inaptos permanentes na triagem clínica para a doação de sangue, visando identificar fatores diferenciais. Constou de estudo caso-referente realizado no Hemocentro de Belo Horizonte (1994-1995, a partir de um inquérito envolvendo 3.527 candidatos à doação. Comparações das características dos candidatos aptos e inaptos foram realizadas, estratificadas por sexo. Regressão logística multinomial foi utilizada para investigar os fatores associados à aptidão para a doação. Os candidatos à doação se assemelhavam quanto ao nível socioeconômico e eram dissimilares na distribuição por sexo, faixa etária e tipo de doação. Para ambos os sexos, as seguintes características se associaram estatisticamente à aptidão: ser mais jovem (18 a 29 anos, ter união estável, estar trabalhando e não possuir automóvel. Para homens incluiu-se, ainda, ter até duas pessoas por dormitório na residência. Distintos perfis demográficos e socioeconômicos foram identificados, de acordo com o sexo e categorias de aptidão, com maior similaridade entre o perfil dos indivíduos inaptos clínicos temporários, principalmente mulheres, com o dos aptos clínicos. Portanto, justifica-se a adoção de múltiplas estratégias de captação de doadores para atingir públicos alvos específicos.Over the last decades, growing concern regarding transfusional safety has been observed, parallel to demographic and social changes as well as

  20. Family refusal to donate organs and tissue for transplantation El rechazo familiar al pedido de donación de órganos y tejidos para transplante A recusa familiar para a doaçao de órgãos e tecidos para transplante

    Directory of Open Access Journals (Sweden)

    Edvaldo Leal de Moraes

    2008-06-01

    orienten la actuación de los profesionales en el tratamiento dado a los familiares de potenciales donadores.A pesquisa teve como objetivo conhecer a percepção dos familiares de potenciais doadores sobre o processo de tomada de decisão para recusar a doação de órgãos e tecidos para transplante. Para compreender a percepção dos familiares, foi utilizada pesquisa qualitativa, segundo a modalidade estrutura do fenômeno situado. Foram entrevistados oito familiares, resgatando quatro temas e quatorze subtemas, após análise dos discursos. As proposições que emergiram revelaram que a essência do fenômeno foi desvelada como vivenciar uma situação de choque e desespero com a internação do familiar, de desconfiança com a solicitação da doação dos órgãos, de negação da morte encefálica, de sofrimento e desgaste diante da perda do ente querido, de conflitos familiares para a tomada de decisão e de múltiplas causas para a recusa da doação. Sendo assim, o conhecimento desse fenômeno pode oferecer elementos que norteiem a atuação dos profissionais junto aos familiares de potenciais doadores.

  1. Pensamento Lean e cuidado do paciente em morte encefálica no processo de doação de órgãos Pensamiento Lean y cuidado del paciente con muerte encefálica en el proceso de donación de órganos Lean thinking and brain-dead patient assistance in the organ donation process

    Directory of Open Access Journals (Sweden)

    Aline Lima Pestana

    2013-02-01

    Full Text Available A doação de órgãos é um processo complexo que desafia os profissionais e gestores do sistema de saúde. Este estudo objetiva apresentar um modelo teórico de organização do cuidado ao paciente em morte encefálica e o processo de doação de órgãos, balizado pelas principais ideias do pensamento Lean que possibilitam a melhoria da produção a partir de ciclos de planejamentos e criação de um ambiente propício para o sucesso da sua implementação. O pensamento Lean pode tornar mais eficaz e eficiente o processo de doação de órgãos e contribuir com a sua melhoria, a partir da sistematização das informações e capacitação dos profissionais para a excelência do cuidado. O modelo apresentado configura-se como um referencial disponível para validação e aplicação pelos profissionais e gestores de saúde e enfermagem na prática da gestão do cuidado ao paciente potencial doador de órgãos em morte encefálica e respectiva demanda por transplante.La donación de órganos es un proceso complejo que desafía a profesionales y gerenciadores del sistema de salud. Se objetiva presentar un modelo teórico de organización del cuidado al paciente con muerte encefálica y el proceso de donación de órganos, orientado por las principales ideas del pensamiento Lean que posibilitan la mejora de producción mediante ciclos de planificación y creación de ambiente propicio para el éxito en su implementación. El pensamiento Lean puede mejorar eficacia y eficiencia del proceso de donación de órganos y contribuir a su mejora, a partir de la sistematización de informaciones y capacitación de los profesionales para la excelencia del cuidado. El modelo presentado configura un referencial disponible para validación y aplicación por parte de profesionales y administradores de salud y enfermería en la práctica de la gestión de cuidado al paciente potencial donante de órganos con muerte encefálica y las respectivas solicitudes de

  2. Family considerations about the decision to refuse organ donation Ponderaciones de familiares sobre la decisión de rechazar la donación de órganos Ponderações de familiares sobre a decisão de recusar a doação de órgãos

    Directory of Open Access Journals (Sweden)

    Gerlene Grudka Lira

    2012-01-01

    amparada en el contexto de la atención y acogida hospitalaria recibido, así como en valores culturales y religiosos.OBJETIVOS: Compreender as representações sociais que nortearam a decisão familiar de recusar a doação de órgãos para transplante e identificar as ações do entorno social que influenciaram esta recusa. MÉTODOS: Estudo de natureza qualitativa, utilizando um desenho descritivo exploratório. Foram entrevistados nove familiares, entre fevereiro e agosto de 2009, cuja morte do parente havia sido notificada regularmente pela Central de Transplantes de Pernambuco. Os depoimentos obtidos sofreram análise de conteúdo na modalidade temática. RESULTADOS: Emergiram três temas que fundamentaram este estudo: o modelo de atenção e gestão dos serviços de saúde é decisivo na recusa da doação; o corpo é inviolável e crença na possibilidade de retorno à vida - coração como sede da vida e fé reforçando a esperança. CONCLUSÃO: A recusa dos participantes para doação de órgãos esteve amparada no contexto do atendimento e do acolhimento hospitalar recebido, bem como em valores culturais e religiosos.

  3. Variable Kernel Density Estimation

    OpenAIRE

    Terrell, George R.; Scott, David W.

    1992-01-01

    We investigate some of the possibilities for improvement of univariate and multivariate kernel density estimates by varying the window over the domain of estimation, pointwise and globally. Two general approaches are to vary the window width by the point of estimation and by point of the sample observation. The first possibility is shown to be of little efficacy in one variable. In particular, nearest-neighbor estimators in all versions perform poorly in one and two dimensions, but begin to b...

  4. Fuel Burn Estimation Model

    Science.gov (United States)

    Chatterji, Gano

    2011-01-01

    Conclusions: Validated the fuel estimation procedure using flight test data. A good fuel model can be created if weight and fuel data are available. Error in assumed takeoff weight results in similar amount of error in the fuel estimate. Fuel estimation error bounds can be determined.

  5. Optimal fault signal estimation

    NARCIS (Netherlands)

    Stoorvogel, Antonie Arij; Niemann, H.H.; Saberi, A.; Sannuti, P.

    2002-01-01

    We consider here both fault identification and fault signal estimation. Regarding fault identification, we seek either exact or almost fault identification. On the other hand, regarding fault signal estimation, we seek either $H_2$ optimal, $H_2$ suboptimal or Hinfinity suboptimal estimation. By

  6. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  7. 极化敏感L型阵模值约束的多参数联合估计%Multi-Parameters Estimation for L-Shaped Polarization Sensitive Array Using the Modulus Constraint

    Institute of Scientific and Technical Information of China (English)

    张远芳; 周正; 李会勇

    2016-01-01

    对于极化敏感 L 型阵列的多参数联合估计问题,采用传统的多重信号分类(MUSIC)算法所需计算量大,采用旋转不变子空间(ESPRIT)算法需要考虑参数配对问题。提出了模值约束下的求根多重信号分类(root-MUSIC)算法,首先利用 L 型阵列中两个相互垂直的线阵构造两子阵接收数据的自相关函数,采用 root-MUSIC 算法进行波达方向角(DOA)估计,然后根据模值约束条件构造代价函数,通过闭合式解得到极化参数估计。该算法与传统 MUSIC 算法相比,大大减少了计算量,同时能够实现参数自动配对,避免了 ESPRIT 算法的不足。计算机仿真结果表明,该算法的角度估计性能与传统 MUSIC 算法接近,优于ESPRIT 算法,且算法收敛速度快。%A large amount of computation is required when using the traditional MUSIC algorithm and the parameter matching problem should be considered when using ESPRIT algorithm for multi-parameters estimation of L-shaped polarization sensitive array.A root-MUSIC algorithm with modulus constraint is pro-posed.This algorithm estimates the DOA and polarization parameters in two separate steps.In step one,the autocorrelation function of the received data from two mutually vertical linear arrays is constructed,and DOA parameter is estimated by root-MUSIC algorithm;in step two,the cost function is constructed according to constraint condition and polarization parameters are obtained with closed-form formulas.Compared with the traditional MUSIC algorithm,the proposed algorithm greatly reduces the amount of calculation.It can realize automatic matching parameters at the same time,which avoids the deficiency of the ESPRIT algorithm.The computer simulation results show that the angle estimation performance of the proposed algorithm is close to traditional MUSIC algorithm,and is better than ESPRIT algorithm.Furthermore,the proposed algorithm has fast convergence speed.

  8. Adjusting estimative prediction limits

    OpenAIRE

    Masao Ueki; Kaoru Fueda

    2007-01-01

    This note presents a direct adjustment of the estimative prediction limit to reduce the coverage error from a target value to third-order accuracy. The adjustment is asymptotically equivalent to those of Barndorff-Nielsen & Cox (1994, 1996) and Vidoni (1998). It has a simpler form with a plug-in estimator of the coverage probability of the estimative limit at the target value. Copyright 2007, Oxford University Press.

  9. Estimation of measurement variances

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    In the previous two sessions, it was assumed that the measurement error variances were known quantities when the variances of the safeguards indices were calculated. These known quantities are actually estimates based on historical data and on data generated by the measurement program. Session 34 discusses how measurement error parameters are estimated for different situations. The various error types are considered. The purpose of the session is to enable participants to: (1) estimate systematic error variances from standard data; (2) estimate random error variances from data as replicate measurement data; (3) perform a simple analysis of variances to characterize the measurement error structure when biases vary over time

  10. Electrical estimating methods

    CERN Document Server

    Del Pico, Wayne J

    2014-01-01

    Simplify the estimating process with the latest data, materials, and practices Electrical Estimating Methods, Fourth Edition is a comprehensive guide to estimating electrical costs, with data provided by leading construction database RS Means. The book covers the materials and processes encountered by the modern contractor, and provides all the information professionals need to make the most precise estimate. The fourth edition has been updated to reflect the changing materials, techniques, and practices in the field, and provides the most recent Means cost data available. The complexity of el

  11. Maximum likely scale estimation

    DEFF Research Database (Denmark)

    Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo

    2005-01-01

    A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...

  12. Cost function estimation

    DEFF Research Database (Denmark)

    Andersen, C K; Andersen, K; Kragh-Sørensen, P

    2000-01-01

    on these criteria, a two-part model was chosen. In this model, the probability of incurring any costs was estimated using a logistic regression, while the level of the costs was estimated in the second part of the model. The choice of model had a substantial impact on the predicted health care costs, e...

  13. Software cost estimation

    NARCIS (Netherlands)

    Heemstra, F.J.

    1992-01-01

    The paper gives an overview of the state of the art of software cost estimation (SCE). The main questions to be answered in the paper are: (1) What are the reasons for overruns of budgets and planned durations? (2) What are the prerequisites for estimating? (3) How can software development effort be

  14. Software cost estimation

    NARCIS (Netherlands)

    Heemstra, F.J.; Heemstra, F.J.

    1993-01-01

    The paper gives an overview of the state of the art of software cost estimation (SCE). The main questions to be answered in the paper are: (1) What are the reasons for overruns of budgets and planned durations? (2) What are the prerequisites for estimating? (3) How can software development effort be

  15. Coherence in quantum estimation

    Science.gov (United States)

    Giorda, Paolo; Allegra, Michele

    2018-01-01

    The geometry of quantum states provides a unifying framework for estimation processes based on quantum probes, and it establishes the ultimate bounds of the achievable precision. We show a relation between the statistical distance between infinitesimally close quantum states and the second order variation of the coherence of the optimal measurement basis with respect to the state of the probe. In quantum phase estimation protocols, this leads to propose coherence as the relevant resource that one has to engineer and control to optimize the estimation precision. Furthermore, the main object of the theory i.e. the symmetric logarithmic derivative, in many cases allows one to identify a proper factorization of the whole Hilbert space in two subsystems. The factorization allows one to discuss the role of coherence versus correlations in estimation protocols; to show how certain estimation processes can be completely or effectively described within a single-qubit subsystem; and to derive lower bounds for the scaling of the estimation precision with the number of probes used. We illustrate how the framework works for both noiseless and noisy estimation procedures, in particular those based on multi-qubit GHZ-states. Finally we succinctly analyze estimation protocols based on zero-temperature critical behavior. We identify the coherence that is at the heart of their efficiency, and we show how it exhibits the non-analyticities and scaling behavior proper of a large class of quantum phase transitions.

  16. Overconfidence in Interval Estimates

    Science.gov (United States)

    Soll, Jack B.; Klayman, Joshua

    2004-01-01

    Judges were asked to make numerical estimates (e.g., "In what year was the first flight of a hot air balloon?"). Judges provided high and low estimates such that they were X% sure that the correct answer lay between them. They exhibited substantial overconfidence: The correct answer fell inside their intervals much less than X% of the time. This…

  17. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    . The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested......In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence...... and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set...

  18. Optomechanical parameter estimation

    International Nuclear Information System (INIS)

    Ang, Shan Zheng; Tsang, Mankei; Harris, Glen I; Bowen, Warwick P

    2013-01-01

    We propose a statistical framework for the problem of parameter estimation from a noisy optomechanical system. The Cramér–Rao lower bound on the estimation errors in the long-time limit is derived and compared with the errors of radiometer and expectation–maximization (EM) algorithms in the estimation of the force noise power. When applied to experimental data, the EM estimator is found to have the lowest error and follow the Cramér–Rao bound most closely. Our analytic results are envisioned to be valuable to optomechanical experiment design, while the EM algorithm, with its ability to estimate most of the system parameters, is envisioned to be useful for optomechanical sensing, atomic magnetometry and fundamental tests of quantum mechanics. (paper)

  19. CHANNEL ESTIMATION TECHNIQUE

    DEFF Research Database (Denmark)

    2015-01-01

    A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the communicat......A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over...... the communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including...... filter characteristics of at least one known transceiver filter arranged in the communication channel....

  20. Radiation risk estimation

    International Nuclear Information System (INIS)

    Schull, W.J.; Texas Univ., Houston, TX

    1992-01-01

    Estimation of the risk of cancer following exposure to ionizing radiation remains largely empirical, and models used to adduce risk incorporate few, if any, of the advances in molecular biology of a past decade or so. These facts compromise the estimation risk where the epidemiological data are weakest, namely, at low doses and dose rates. Without a better understanding of the molecular and cellular events ionizing radiation initiates or promotes, it seems unlikely that this situation will improve. Nor will the situation improve without further attention to the identification and quantitative estimation of the effects of those host and environmental factors that enhance or attenuate risk. (author)

  1. Estimation of Jump Tails

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Victor

    We propose a new and flexible non-parametric framework for estimating the jump tails of Itô semimartingale processes. The approach is based on a relatively simple-to-implement set of estimating equations associated with the compensator for the jump measure, or its "intensity", that only utilizes...... the weak assumption of regular variation in the jump tails, along with in-fill asymptotic arguments for uniquely identifying the "large" jumps from the data. The estimation allows for very general dynamic dependencies in the jump tails, and does not restrict the continuous part of the process...... and the temporal variation in the stochastic volatility. On implementing the new estimation procedure with actual high-frequency data for the S&P 500 aggregate market portfolio, we find strong evidence for richer and more complex dynamic dependencies in the jump tails than hitherto entertained in the literature....

  2. Bridged Race Population Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — Population estimates from "bridging" the 31 race categories used in Census 2000, as specified in the 1997 Office of Management and Budget (OMB) race and ethnicity...

  3. Estimation of measurement variances

    International Nuclear Information System (INIS)

    Jaech, J.L.

    1984-01-01

    The estimation of measurement error parameters in safeguards systems is discussed. Both systematic and random errors are considered. A simple analysis of variances to characterize the measurement error structure with biases varying over time is presented

  4. APLIKASI SPLINE ESTIMATOR TERBOBOT

    Directory of Open Access Journals (Sweden)

    I Nyoman Budiantara

    2001-01-01

    Full Text Available We considered the nonparametric regression model : Zj = X(tj + ej, j = 1,2,…,n, where X(tj is the regression curve. The random error ej are independently distributed normal with a zero mean and a variance s2/bj, bj > 0. The estimation of X obtained by minimizing a Weighted Least Square. The solution of this optimation is a Weighted Spline Polynomial. Further, we give an application of weigted spline estimator in nonparametric regression. Abstract in Bahasa Indonesia : Diberikan model regresi nonparametrik : Zj = X(tj + ej, j = 1,2,…,n, dengan X (tj kurva regresi dan ej sesatan random yang diasumsikan berdistribusi normal dengan mean nol dan variansi s2/bj, bj > 0. Estimasi kurva regresi X yang meminimumkan suatu Penalized Least Square Terbobot, merupakan estimator Polinomial Spline Natural Terbobot. Selanjutnya diberikan suatu aplikasi estimator spline terbobot dalam regresi nonparametrik. Kata kunci: Spline terbobot, Regresi nonparametrik, Penalized Least Square.

  5. Fractional cointegration rank estimation

    DEFF Research Database (Denmark)

    Lasak, Katarzyna; Velasco, Carlos

    the parameters of the model under the null hypothesis of the cointegration rank r = 1, 2, ..., p-1. This step provides consistent estimates of the cointegration degree, the cointegration vectors, the speed of adjustment to the equilibrium parameters and the common trends. In the second step we carry out a sup......-likelihood ratio test of no-cointegration on the estimated p - r common trends that are not cointegrated under the null. The cointegration degree is re-estimated in the second step to allow for new cointegration relationships with different memory. We augment the error correction model in the second step...... to control for stochastic trend estimation effects from the first step. The critical values of the tests proposed depend only on the number of common trends under the null, p - r, and on the interval of the cointegration degrees b allowed, but not on the true cointegration degree b0. Hence, no additional...

  6. Estimation of spectral kurtosis

    Science.gov (United States)

    Sutawanir

    2017-03-01

    Rolling bearings are the most important elements in rotating machinery. Bearing frequently fall out of service for various reasons: heavy loads, unsuitable lubrications, ineffective sealing. Bearing faults may cause a decrease in performance. Analysis of bearing vibration signals has attracted attention in the field of monitoring and fault diagnosis. Bearing vibration signals give rich information for early detection of bearing failures. Spectral kurtosis, SK, is a parameter in frequency domain indicating how the impulsiveness of a signal varies with frequency. Faults in rolling bearings give rise to a series of short impulse responses as the rolling elements strike faults, SK potentially useful for determining frequency bands dominated by bearing fault signals. SK can provide a measure of the distance of the analyzed bearings from a healthy one. SK provides additional information given by the power spectral density (psd). This paper aims to explore the estimation of spectral kurtosis using short time Fourier transform known as spectrogram. The estimation of SK is similar to the estimation of psd. The estimation falls in model-free estimation and plug-in estimator. Some numerical studies using simulations are discussed to support the methodology. Spectral kurtosis of some stationary signals are analytically obtained and used in simulation study. Kurtosis of time domain has been a popular tool for detecting non-normality. Spectral kurtosis is an extension of kurtosis in frequency domain. The relationship between time domain and frequency domain analysis is establish through power spectrum-autocovariance Fourier transform. Fourier transform is the main tool for estimation in frequency domain. The power spectral density is estimated through periodogram. In this paper, the short time Fourier transform of the spectral kurtosis is reviewed, a bearing fault (inner ring and outer ring) is simulated. The bearing response, power spectrum, and spectral kurtosis are plotted to

  7. Approximate Bayesian recursive estimation

    Czech Academy of Sciences Publication Activity Database

    Kárný, Miroslav

    2014-01-01

    Roč. 285, č. 1 (2014), s. 100-111 ISSN 0020-0255 R&D Projects: GA ČR GA13-13502S Institutional support: RVO:67985556 Keywords : Approximate parameter estimation * Bayesian recursive estimation * Kullback–Leibler divergence * Forgetting Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 4.038, year: 2014 http://library.utia.cas.cz/separaty/2014/AS/karny-0425539.pdf

  8. Ranking as parameter estimation

    Czech Academy of Sciences Publication Activity Database

    Kárný, Miroslav; Guy, Tatiana Valentine

    2009-01-01

    Roč. 4, č. 2 (2009), s. 142-158 ISSN 1745-7645 R&D Projects: GA MŠk 2C06001; GA AV ČR 1ET100750401; GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : ranking * Bayesian estimation * negotiation * modelling Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2009/AS/karny- ranking as parameter estimation.pdf

  9. Maximal combustion temperature estimation

    International Nuclear Information System (INIS)

    Golodova, E; Shchepakina, E

    2006-01-01

    This work is concerned with the phenomenon of delayed loss of stability and the estimation of the maximal temperature of safe combustion. Using the qualitative theory of singular perturbations and canard techniques we determine the maximal temperature on the trajectories located in the transition region between the slow combustion regime and the explosive one. This approach is used to estimate the maximal temperature of safe combustion in multi-phase combustion models

  10. Low-Complexity Spatial-Temporal Filtering Method via Compressive Sensing for Interference Mitigation in a GNSS Receiver

    Directory of Open Access Journals (Sweden)

    Chung-Liang Chang

    2014-01-01

    Full Text Available A compressive sensing based array processing method is proposed to lower the complexity, and computation load of array system and to maintain the robust antijam performance in global navigation satellite system (GNSS receiver. Firstly, the spatial and temporal compressed matrices are multiplied with array signal, which results in a small size array system. Secondly, the 2-dimensional (2D minimum variance distortionless response (MVDR beamformer is employed in proposed system to mitigate the narrowband and wideband interference simultaneously. The iterative process is performed to find optimal spatial and temporal gain vector by MVDR approach, which enhances the steering gain of direction of arrival (DOA of interest. Meanwhile, the null gain is set at DOA of interference. Finally, the simulated navigation signal is generated offline by the graphic user interface tool and employed in the proposed algorithm. The theoretical analysis results using the proposed algorithm are verified based on simulated results.

  11. Entrevista familiar no processo de doação de órgãos e tecidos para transplante Entrevista familiar en el proceso de donación de órganos y tejidos para transplante Family interview in the process of donating organs and tissues for transplantation

    Directory of Open Access Journals (Sweden)

    Marcelo José dos Santos

    2012-01-01

    Full Text Available OBJETIVO: Desvelar o significado atribuído pelos profissionais que atuam em Serviços de Procura de Órgãos e Tecidos à entrevista familiar no processo de doação de órgãos e tecidos para transplante. MÉTODOS: Pesquisa de abordagem qualitativa, na vertente fenomenológica, conforme a modalidade "estrutura do fenômeno situado". Participaram do estudo, 12 profissionais. RESULTADOS: Após a análise das entrevistas, foi desvelado o significado atribuído pelos profissionais à entrevista. CONCLUSÕES: As proposições que emergiram revelaram que a entrevista familiar é uma etapa importante, pois trata da possibilidade da doação de órgãos e tecidos para salvar e/ou melhorar a qualidade de vida de pessoas que necessitam de um transplante. Este procedimento é complexo, visto que envolve aspectos relativos ao entrevistador, ao entrevistado e ao local da entrevista, além de questões éticas e legais. Também evidenciam a necessidade de capacitação profissional para conhecer, identificar e lidar com fatores que facilitam ou dificultam o diálogo com os familiares.OBJETIVO: Develar el significado atribuído por los profesionales que actúan en Servicios de Procura de Órganos y Tejidos a la entrevista familiar en el proceso de donación de órganos y tejidos para transplante. MÉTODOS: Investigación de abordaje cualitativo, en la vertiente fenomenológica, conforme la modalidad "estructura del fenómeno situado". Participaron en el estudio, 12 profesionales. RESULTADOS: Después del análisis de las entrevistas, fue develado el significado atribuído por los profesionales a la entrevista. CONCLUSIONES: Las proposiciones que emergieron revelaron que la entrevista familiar es una etapa importante, pues trata de la posibilidad de la donación de órganos y tejidos para salvar y/o mejorar la calidad de vida de personas que necesitan de un transplante. Este procedimiento es complejo, pues involucra aspectos relativos al entrevistador, al

  12. 基于MUSIC-Group Delay算法的相邻相干信号源定位%Closely spaced coherent-source localization based on MUSIC-group delay algorithm

    Institute of Scientific and Technical Information of China (English)

    郑家芝

    2016-01-01

    为了准确的进行相邻的相干信号源定位,提出了一种基于多重信号分类群延迟(MUSIC-group delay)的改进算法。首先,将空间平滑技术引入到波达方向(DoA)估计当中去除部分相干信号。由于在信号源相邻的情况下子空间算法的性能降低,就结合了 MUSIC-Group Delay算法来区分相邻的信号源,这种方法因为自身的加和性通过 MUSIC 相位谱来计算群延迟函数,从而能估计出相邻的信号源。理论分析和仿真结果表明提出的方法估计相邻的相干信号源比子空间算法更精确,分辨率更高。%In this paper,the closely spaced coherent-source localization is considered,and an improved method based on the group delay of Multiple Signal Classification (MUSIC)is presented.Firstly,we introduce the spatial smoothing technique into direction of arrival (DoA)estimation to get rid of the coherent part of signals.Due to the degraded per-formance of sub-space based methods on the condition of nearby sources,we then utilize the MUSIC-Group Delay algo-rithm to distinguish the closely spaced sources,which can resolve spatially close sources by the use of the group delay function computed from the MUSIC phase spectrum for efficient DoA estimation owing to its spatial additive property. Theoretical analysis and simulation results demonstrate that the proposed approach can estimate the DoA of the coherent close signal sources more precisely and have higher resolution compared with sub-space based methods.

  13. Shooter position estimation with muzzle blast and shockwave measurements from separate locations

    Science.gov (United States)

    Grasing, David

    2016-05-01

    There are two acoustical events associated with small arms fire: the muzzle blast (created by bullets being expelled from the barrel of the weapon), and the shockwave (created by bullets which exceed the speed of sound). Assuming the ballistics of a round are known, the times and directions of arrival of the acoustic events furnish sufficient information to determine the origin of the shot. Existing methods tacitly assume that it is a single sensor which makes measurements of the times and direction of arrival. If the sensor is located past the point where the bullet goes transonic or if the sensor is far off the axis of the shot line a single sensor localization become highly inaccurate due to the ill-conditioning of the localization problem. In this paper, a more general approach is taken which allows for localizations from measurements made at separate locations. There are considerable advantages to this approach, the most noteworthy of which is the improvement in localization accuracy due to the improvement in the conditioning of the problem. Additional benefits include: the potential to locate in cases where a single sensor has insufficient information, furnishing high quality initialization to data fusion algorithms, and the potential to identify the round from a set of possible rounds.

  14. Thermodynamic estimation: Ionic materials

    International Nuclear Information System (INIS)

    Glasser, Leslie

    2013-01-01

    Thermodynamics establishes equilibrium relations among thermodynamic parameters (“properties”) and delineates the effects of variation of the thermodynamic functions (typically temperature and pressure) on those parameters. However, classical thermodynamics does not provide values for the necessary thermodynamic properties, which must be established by extra-thermodynamic means such as experiment, theoretical calculation, or empirical estimation. While many values may be found in the numerous collected tables in the literature, these are necessarily incomplete because either the experimental measurements have not been made or the materials may be hypothetical. The current paper presents a number of simple and relible estimation methods for thermodynamic properties, principally for ionic materials. The results may also be used as a check for obvious errors in published values. The estimation methods described are typically based on addition of properties of individual ions, or sums of properties of neutral ion groups (such as “double” salts, in the Simple Salt Approximation), or based upon correlations such as with formula unit volumes (Volume-Based Thermodynamics). - Graphical abstract: Thermodynamic properties of ionic materials may be readily estimated by summation of the properties of individual ions, by summation of the properties of ‘double salts’, and by correlation with formula volume. Such estimates may fill gaps in the literature, and may also be used as checks of published values. This simplicity arises from exploitation of the fact that repulsive energy terms are of short range and very similar across materials, while coulombic interactions provide a very large component of the attractive energy in ionic systems. Display Omitted - Highlights: • Estimation methods for thermodynamic properties of ionic materials are introduced. • Methods are based on summation of single ions, multiple salts, and correlations. • Heat capacity, entropy

  15. Distribution load estimation - DLE

    Energy Technology Data Exchange (ETDEWEB)

    Seppaelae, A. [VTT Energy, Espoo (Finland)

    1996-12-31

    The load research project has produced statistical information in the form of load models to convert the figures of annual energy consumption to hourly load values. The reliability of load models is limited to a certain network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to make improvements in the load models. Distribution load estimation (DLE) is the method developed here to improve load estimates from the load models. The method is also quite cheap to apply as it utilises information that is already available in SCADA systems

  16. Generalized estimating equations

    CERN Document Server

    Hardin, James W

    2002-01-01

    Although powerful and flexible, the method of generalized linear models (GLM) is limited in its ability to accurately deal with longitudinal and clustered data. Developed specifically to accommodate these data types, the method of Generalized Estimating Equations (GEE) extends the GLM algorithm to accommodate the correlated data encountered in health research, social science, biology, and other related fields.Generalized Estimating Equations provides the first complete treatment of GEE methodology in all of its variations. After introducing the subject and reviewing GLM, the authors examine th

  17. Digital Quantum Estimation

    Science.gov (United States)

    Hassani, Majid; Macchiavello, Chiara; Maccone, Lorenzo

    2017-11-01

    Quantum metrology calculates the ultimate precision of all estimation strategies, measuring what is their root-mean-square error (RMSE) and their Fisher information. Here, instead, we ask how many bits of the parameter we can recover; namely, we derive an information-theoretic quantum metrology. In this setting, we redefine "Heisenberg bound" and "standard quantum limit" (the usual benchmarks in the quantum estimation theory) and show that the former can be attained only by sequential strategies or parallel strategies that employ entanglement among probes, whereas parallel-separable strategies are limited by the latter. We highlight the differences between this setting and the RMSE-based one.

  18. Distribution load estimation - DLE

    Energy Technology Data Exchange (ETDEWEB)

    Seppaelae, A [VTT Energy, Espoo (Finland)

    1997-12-31

    The load research project has produced statistical information in the form of load models to convert the figures of annual energy consumption to hourly load values. The reliability of load models is limited to a certain network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to make improvements in the load models. Distribution load estimation (DLE) is the method developed here to improve load estimates from the load models. The method is also quite cheap to apply as it utilises information that is already available in SCADA systems

  19. Estimating Delays In ASIC's

    Science.gov (United States)

    Burke, Gary; Nesheiwat, Jeffrey; Su, Ling

    1994-01-01

    Verification is important aspect of process of designing application-specific integrated circuit (ASIC). Design must not only be functionally accurate, but must also maintain correct timing. IFA, Intelligent Front Annotation program, assists in verifying timing of ASIC early in design process. This program speeds design-and-verification cycle by estimating delays before layouts completed. Written in C language.

  20. Organizational flexibility estimation

    OpenAIRE

    Komarynets, Sofia

    2013-01-01

    By the help of parametric estimation the evaluation scale of organizational flexibility and its parameters was formed. Definite degrees of organizational flexibility and its parameters for the Lviv region enterprises were determined. Grouping of the enterprises under the existing scale was carried out. Special recommendations to correct the enterprises behaviour were given.

  1. On Functional Calculus Estimates

    NARCIS (Netherlands)

    Schwenninger, F.L.

    2015-01-01

    This thesis presents various results within the field of operator theory that are formulated in estimates for functional calculi. Functional calculus is the general concept of defining operators of the form $f(A)$, where f is a function and $A$ is an operator, typically on a Banach space. Norm

  2. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  3. Quantifying IT estimation risks

    NARCIS (Netherlands)

    Kulk, G.P.; Peters, R.J.; Verhoef, C.

    2009-01-01

    A statistical method is proposed for quantifying the impact of factors that influence the quality of the estimation of costs for IT-enabled business projects. We call these factors risk drivers as they influence the risk of the misestimation of project costs. The method can effortlessly be

  4. Numerical Estimation in Preschoolers

    Science.gov (United States)

    Berteletti, Ilaria; Lucangeli, Daniela; Piazza, Manuela; Dehaene, Stanislas; Zorzi, Marco

    2010-01-01

    Children's sense of numbers before formal education is thought to rely on an approximate number system based on logarithmically compressed analog magnitudes that increases in resolution throughout childhood. School-age children performing a numerical estimation task have been shown to increasingly rely on a formally appropriate, linear…

  5. Estimating Gender Wage Gaps

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2011-01-01

    Course research projects that use easy-to-access real-world data and that generate findings with which undergraduate students can readily identify are hard to find. The authors describe a project that requires students to estimate the current female-male earnings gap for new college graduates. The project also enables students to see to what…

  6. Fast fundamental frequency estimation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom

    2017-01-01

    Modelling signals as being periodic is common in many applications. Such periodic signals can be represented by a weighted sum of sinusoids with frequencies being an integer multiple of the fundamental frequency. Due to its widespread use, numerous methods have been proposed to estimate the funda...

  7. On Gnostical Estimates

    Czech Academy of Sciences Publication Activity Database

    Fabián, Zdeněk

    2017-01-01

    Roč. 56, č. 2 (2017), s. 125-132 ISSN 0973-1377 Institutional support: RVO:67985807 Keywords : gnostic theory * statistics * robust estimates Subject RIV: BB - Applied Statistics, Operational Research OBOR OECD: Statistics and probability http://www.ceser.in/ceserp/index.php/ijamas/article/view/4707

  8. Estimation of morbidity effects

    International Nuclear Information System (INIS)

    Ostro, B.

    1994-01-01

    Many researchers have related exposure to ambient air pollution to respiratory morbidity. To be included in this review and analysis, however, several criteria had to be met. First, a careful study design and a methodology that generated quantitative dose-response estimates were required. Therefore, there was a focus on time-series regression analyses relating daily incidence of morbidity to air pollution in a single city or metropolitan area. Studies that used weekly or monthly average concentrations or that involved particulate measurements in poorly characterized metropolitan areas (e.g., one monitor representing a large region) were not included in this review. Second, studies that minimized confounding ad omitted variables were included. For example, research that compared two cities or regions and characterized them as 'high' and 'low' pollution area were not included because of potential confounding by other factors in the respective areas. Third, concern for the effects of seasonality and weather had to be demonstrated. This could be accomplished by either stratifying and analyzing the data by season, by examining the independent effects of temperature and humidity, and/or by correcting the model for possible autocorrelation. A fourth criterion for study inclusion was that the study had to include a reasonably complete analysis of the data. Such analysis would include an careful exploration of the primary hypothesis as well as possible examination of te robustness and sensitivity of the results to alternative functional forms, specifications, and influential data points. When studies reported the results of these alternative analyses, the quantitative estimates that were judged as most representative of the overall findings were those that were summarized in this paper. Finally, for inclusion in the review of particulate matter, the study had to provide a measure of particle concentration that could be converted into PM10, particulate matter below 10

  9. Histogram Estimators of Bivariate Densities

    National Research Council Canada - National Science Library

    Husemann, Joyce A

    1986-01-01

    One-dimensional fixed-interval histogram estimators of univariate probability density functions are less efficient than the analogous variable-interval estimators which are constructed from intervals...

  10. Automatic trend estimation

    CERN Document Server

    Vamos¸, C˘alin

    2013-01-01

    Our book introduces a method to evaluate the accuracy of trend estimation algorithms under conditions similar to those encountered in real time series processing. This method is based on Monte Carlo experiments with artificial time series numerically generated by an original algorithm. The second part of the book contains several automatic algorithms for trend estimation and time series partitioning. The source codes of the computer programs implementing these original automatic algorithms are given in the appendix and will be freely available on the web. The book contains clear statement of the conditions and the approximations under which the algorithms work, as well as the proper interpretation of their results. We illustrate the functioning of the analyzed algorithms by processing time series from astrophysics, finance, biophysics, and paleoclimatology. The numerical experiment method extensively used in our book is already in common use in computational and statistical physics.

  11. Distribution load estimation (DLE)

    Energy Technology Data Exchange (ETDEWEB)

    Seppaelae, A; Lehtonen, M [VTT Energy, Espoo (Finland)

    1998-08-01

    The load research has produced customer class load models to convert the customers` annual energy consumption to hourly load values. The reliability of load models applied from a nation-wide sample is limited in any specific network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to find improvements to the load models or, in general, improvements to the load estimates. In Distribution Load Estimation (DLE) the measurements from the network are utilized to improve the customer class load models. The results of DLE will be new load models that better correspond to the loading of the distribution network but are still close to the original load models obtained by load research. The principal data flow of DLE is presented

  12. Estimating ISABELLE shielding requirements

    International Nuclear Information System (INIS)

    Stevens, A.J.; Thorndike, A.M.

    1976-01-01

    Estimates were made of the shielding thicknesses required at various points around the ISABELLE ring. Both hadron and muon requirements are considered. Radiation levels at the outside of the shield and at the BNL site boundary are kept at or below 1000 mrem per year and 5 mrem/year respectively. Muon requirements are based on the Wang formula for pion spectra, and the hadron requirements on the hadron cascade program CYLKAZ of Ranft. A muon shield thickness of 77 meters of sand is indicated outside the ring in one area, and hadron shields equivalent to from 2.7 to 5.6 meters in thickness of sand above the ring. The suggested safety allowance would increase these values to 86 meters and 4.0 to 7.2 meters respectively. There are many uncertainties in such estimates, but these last figures are considered to be rather conservative

  13. Variance Function Estimation. Revision.

    Science.gov (United States)

    1987-03-01

    UNLSIFIED RFOSR-TR-87-±112 F49620-85-C-O144 F/C 12/3 NL EEEEEEh LOUA28~ ~ L53 11uLoo MICROOP REOUINTS-’HR ------ N L E U INARF-% - IS %~1 %i % 0111...and 9 jointly. If 7,, 0. and are any preliminary estimators for 71, 6. and 3. define 71 and 6 to be the solutions of (4.1) N1 IN2 (7., ’ Td " ~ - / =0P

  14. Estimating Risk Parameters

    OpenAIRE

    Aswath Damodaran

    1999-01-01

    Over the last three decades, the capital asset pricing model has occupied a central and often controversial place in most corporate finance analysts’ tool chests. The model requires three inputs to compute expected returns – a riskfree rate, a beta for an asset and an expected risk premium for the market portfolio (over and above the riskfree rate). Betas are estimated, by most practitioners, by regressing returns on an asset against a stock index, with the slope of the regression being the b...

  15. Estimating Venezuelas Latent Inflation

    OpenAIRE

    Juan Carlos Bencomo; Hugo J. Montesinos; Hugo M. Montesinos; Jose Roberto Rondo

    2011-01-01

    Percent variation of the consumer price index (CPI) is the inflation indicator most widely used. This indicator, however, has some drawbacks. In addition to measurement errors of the CPI, there is a problem of incongruence between the definition of inflation as a sustained and generalized increase of prices and the traditional measure associated with the CPI. We use data from 1991 to 2005 to estimate a complementary indicator for Venezuela, the highest inflation country in Latin America. Late...

  16. Chernobyl source term estimation

    International Nuclear Information System (INIS)

    Gudiksen, P.H.; Harvey, T.F.; Lange, R.

    1990-09-01

    The Chernobyl source term available for long-range transport was estimated by integration of radiological measurements with atmospheric dispersion modeling and by reactor core radionuclide inventory estimation in conjunction with WASH-1400 release fractions associated with specific chemical groups. The model simulations revealed that the radioactive cloud became segmented during the first day, with the lower section heading toward Scandinavia and the upper part heading in a southeasterly direction with subsequent transport across Asia to Japan, the North Pacific, and the west coast of North America. By optimizing the agreement between the observed cloud arrival times and duration of peak concentrations measured over Europe, Japan, Kuwait, and the US with the model predicted concentrations, it was possible to derive source term estimates for those radionuclides measured in airborne radioactivity. This was extended to radionuclides that were largely unmeasured in the environment by performing a reactor core radionuclide inventory analysis to obtain release fractions for the various chemical transport groups. These analyses indicated that essentially all of the noble gases, 60% of the radioiodines, 40% of the radiocesium, 10% of the tellurium and about 1% or less of the more refractory elements were released. These estimates are in excellent agreement with those obtained on the basis of worldwide deposition measurements. The Chernobyl source term was several orders of magnitude greater than those associated with the Windscale and TMI reactor accidents. However, the 137 Cs from the Chernobyl event is about 6% of that released by the US and USSR atmospheric nuclear weapon tests, while the 131 I and 90 Sr released by the Chernobyl accident was only about 0.1% of that released by the weapon tests. 13 refs., 2 figs., 7 tabs

  17. Estimating Corporate Yield Curves

    OpenAIRE

    Antionio Diaz; Frank Skinner

    2001-01-01

    This paper represents the first study of retail deposit spreads of UK financial institutions using stochastic interest rate modelling and the market comparable approach. By replicating quoted fixed deposit rates using the Black Derman and Toy (1990) stochastic interest rate model, we find that the spread between fixed and variable rates of interest can be modeled (and priced) using an interest rate swap analogy. We also find that we can estimate an individual bank deposit yield curve as a spr...

  18. Estimation of inspection effort

    International Nuclear Information System (INIS)

    Mullen, M.F.; Wincek, M.A.

    1979-06-01

    An overview of IAEA inspection activities is presented, and the problem of evaluating the effectiveness of an inspection is discussed. Two models are described - an effort model and an effectiveness model. The effort model breaks the IAEA's inspection effort into components; the amount of effort required for each component is estimated; and the total effort is determined by summing the effort for each component. The effectiveness model quantifies the effectiveness of inspections in terms of probabilities of detection and quantities of material to be detected, if diverted over a specific period. The method is applied to a 200 metric ton per year low-enriched uranium fuel fabrication facility. A description of the model plant is presented, a safeguards approach is outlined, and sampling plans are calculated. The required inspection effort is estimated and the results are compared to IAEA estimates. Some other applications of the method are discussed briefly. Examples are presented which demonstrate how the method might be useful in formulating guidelines for inspection planning and in establishing technical criteria for safeguards implementation

  19. Qualitative Robustness in Estimation

    Directory of Open Access Journals (Sweden)

    Mohammed Nasser

    2012-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman","serif";} Qualitative robustness, influence function, and breakdown point are three main concepts to judge an estimator from the viewpoint of robust estimation. It is important as well as interesting to study relation among them. This article attempts to present the concept of qualitative robustness as forwarded by first proponents and its later development. It illustrates intricacies of qualitative robustness and its relation with consistency, and also tries to remove commonly believed misunderstandings about relation between influence function and qualitative robustness citing some examples from literature and providing a new counter-example. At the end it places a useful finite and a simulated version of   qualitative robustness index (QRI. In order to assess the performance of the proposed measures, we have compared fifteen estimators of correlation coefficient using simulated as well as real data sets.

  20. Estimating directional epistasis

    Science.gov (United States)

    Le Rouzic, Arnaud

    2014-01-01

    Epistasis, i.e., the fact that gene effects depend on the genetic background, is a direct consequence of the complexity of genetic architectures. Despite this, most of the models used in evolutionary and quantitative genetics pay scant attention to genetic interactions. For instance, the traditional decomposition of genetic effects models epistasis as noise around the evolutionarily-relevant additive effects. Such an approach is only valid if it is assumed that there is no general pattern among interactions—a highly speculative scenario. Systematic interactions generate directional epistasis, which has major evolutionary consequences. In spite of its importance, directional epistasis is rarely measured or reported by quantitative geneticists, not only because its relevance is generally ignored, but also due to the lack of simple, operational, and accessible methods for its estimation. This paper describes conceptual and statistical tools that can be used to estimate directional epistasis from various kinds of data, including QTL mapping results, phenotype measurements in mutants, and artificial selection responses. As an illustration, I measured directional epistasis from a real-life example. I then discuss the interpretation of the estimates, showing how they can be used to draw meaningful biological inferences. PMID:25071828

  1. Adaptive Nonparametric Variance Estimation for a Ratio Estimator ...

    African Journals Online (AJOL)

    Kernel estimators for smooth curves require modifications when estimating near end points of the support, both for practical and asymptotic reasons. The construction of such boundary kernels as solutions of variational problem is a difficult exercise. For estimating the error variance of a ratio estimator, we suggest an ...

  2. Estimation of Lung Ventilation

    Science.gov (United States)

    Ding, Kai; Cao, Kunlin; Du, Kaifang; Amelon, Ryan; Christensen, Gary E.; Raghavan, Madhavan; Reinhardt, Joseph M.

    Since the primary function of the lung is gas exchange, ventilation can be interpreted as an index of lung function in addition to perfusion. Injury and disease processes can alter lung function on a global and/or a local level. MDCT can be used to acquire multiple static breath-hold CT images of the lung taken at different lung volumes, or with proper respiratory control, 4DCT images of the lung reconstructed at different respiratory phases. Image registration can be applied to this data to estimate a deformation field that transforms the lung from one volume configuration to the other. This deformation field can be analyzed to estimate local lung tissue expansion, calculate voxel-by-voxel intensity change, and make biomechanical measurements. The physiologic significance of the registration-based measures of respiratory function can be established by comparing to more conventional measurements, such as nuclear medicine or contrast wash-in/wash-out studies with CT or MR. An important emerging application of these methods is the detection of pulmonary function change in subjects undergoing radiation therapy (RT) for lung cancer. During RT, treatment is commonly limited to sub-therapeutic doses due to unintended toxicity to normal lung tissue. Measurement of pulmonary function may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy. This chapter reviews the basic measures to estimate regional ventilation from image registration of CT images, the comparison of them to the existing golden standard and the application in radiation therapy.

  3. Estimating Subjective Probabilities

    DEFF Research Database (Denmark)

    Andersen, Steffen; Fountain, John; Harrison, Glenn W.

    2014-01-01

    either construct elicitation mechanisms that control for risk aversion, or construct elicitation mechanisms which undertake 'calibrating adjustments' to elicited reports. We illustrate how the joint estimation of risk attitudes and subjective probabilities can provide the calibration adjustments...... that theory calls for. We illustrate this approach using data from a controlled experiment with real monetary consequences to the subjects. This allows the observer to make inferences about the latent subjective probability, under virtually any well-specified model of choice under subjective risk, while still...

  4. Estimating NHL Scoring Rates

    OpenAIRE

    Buttrey, Samuel E.; Washburn, Alan R.; Price, Wilson L.; Operations Research

    2011-01-01

    The article of record as published may be located at http://dx.doi.org/10.2202/1559-0410.1334 We propose a model to estimate the rates at which NHL teams score and yield goals. In the model, goals occur as if from a Poisson process whose rate depends on the two teams playing, the home-ice advantage, and the manpower (power-play, short-handed) situation. Data on all the games from the 2008-2009 season was downloaded and processed into a form suitable for the analysis. The model...

  5. Risk estimation and evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, R A.D.

    1982-10-01

    Risk assessment involves subjectivity, which makes objective decision making difficult in the nuclear power debate. The author reviews the process and uncertainties of estimating risks as well as the potential for misinterpretation and misuse. Risk data from a variety of aspects cannot be summed because the significance of different risks is not comparable. A method for including political, social, moral, psychological, and economic factors, environmental impacts, catastrophes, and benefits in the evaluation process could involve a broad base of lay and technical consultants, who would explain and argue their evaluation positions. 15 references. (DCK)

  6. Estimating Gear Teeth Stiffness

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffness’s of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact length is constant....

  7. Mixtures Estimation and Applications

    CERN Document Server

    Mengersen, Kerrie; Titterington, Mike

    2011-01-01

    This book uses the EM (expectation maximization) algorithm to simultaneously estimate the missing data and unknown parameter(s) associated with a data set. The parameters describe the component distributions of the mixture; the distributions may be continuous or discrete. The editors provide a complete account of the applications, mathematical structure and statistical analysis of finite mixture distributions along with MCMC computational methods, together with a range of detailed discussions covering the applications of the methods and features chapters from the leading experts on the subject

  8. Robust Wave Resource Estimation

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    2013-01-01

    density estimates of the PDF as a function both of Hm0 and Tp, and Hm0 and T0;2, together with the mean wave power per unit crest length, Pw, as a function of Hm0 and T0;2. The wave elevation parameters, from which the wave parameters are calculated, are filtered to correct or remove spurious data....... An overview is given of the methods used to do this, and a method for identifying outliers of the wave elevation data, based on the joint distribution of wave elevations and accelerations, is presented. The limitations of using a JONSWAP spectrum to model the measured wave spectra as a function of Hm0 and T0......;2 or Hm0 and Tp for the Hanstholm site data are demonstrated. As an alternative, the non-parametric loess method, which does not rely on any assumptions about the shape of the wave elevation spectra, is used to accurately estimate Pw as a function of Hm0 and T0;2....

  9. Estimations of actual availability

    International Nuclear Information System (INIS)

    Molan, M.; Molan, G.

    2001-01-01

    Adaptation of working environment (social, organizational, physical and physical) should assure higher level of workers' availability and consequently higher level of workers' performance. A special theoretical model for description of connections between environmental factors, human availability and performance was developed and validated. The central part of the model is evaluations of human actual availability in the real working situation or fitness for duties self-estimation. The model was tested in different working environments. On the numerous (2000) workers, standardized values and critical limits for an availability questionnaire were defined. Standardized method was used in identification of the most important impact of environmental factors. Identified problems were eliminated by investments in the organization in modification of selection and training procedures in humanization of working .environment. For workers with behavioural and health problems individual consultancy was offered. The described method is a tool for identification of impacts. In combination with behavioural analyses and mathematical analyses of connections, it offers possibilities to keep adequate level of human availability and fitness for duty in each real working situation. The model should be a tool for achieving adequate level of nuclear safety by keeping the adequate level of workers' availability and fitness for duty. For each individual worker possibility for estimation of level of actual fitness for duty is possible. Effects of prolonged work and additional tasks should be evaluated. Evaluations of health status effects and ageing are possible on the individual level. (author)

  10. 基于内插阵列变换的非圆信号MUSIC算法%Non-Circular MUSIC Algorithm Based on Virtual Interpolated Array

    Institute of Scientific and Technical Information of China (English)

    陈浩; 宋爱民; 刘剑

    2012-01-01

    针对非圆信号的波达方向(DOA)估计问题,提出一种基于内插阵列变换的非圆信号MUSIC算法(VIA-NC-MUSIC算法).利用真实阵列流型与虚拟阵列流型之间的变换矩阵,将真实协方差矩阵变换为虚拟协方差矩阵,再对虚拟协方差矩阵进行奇异值分解(SVD),利用信号子空间与噪声子空间的正交性,得出算法的空间谱函数.仿真实验表明:存在阵元位置误差的情况下,新算法通过对阵元位置校准数据进行内插阵列变换(VIA),取得与阵元位置校准的非圆信号MUSIC算法(NC-MUSIC算法)相当的估计性能,保持了高估计精度、阵列扩展能力等优点.%A non-circular MUSIC (multiple signal classification) algorithm based on virtual interpolated array (VIA-INC-MUSIC algorithm) is proposed to estimate the direction of arrival (DOA) problem of non-circular signals. By utilizing transformation matrix which is obtained through the real array manifold and virtual array manifold, the real covariance matrix can be converted to virtual covariance matrix, and the spatial spectrum function can be obtained by orthogonality of signal subspace and noise subspace after singularity value decomposition (SVD) of virtual covariance matrix. Simulation results show that if sensor position errors exist, the performance of the new algorithm is similar to the calibrated non-circular MUSIC algorithm ( NC-MU-SIC algorithm) by using virtual interpolated array (VIA) for the calibrated sensor position data, and this algorithm also keeps the performance in array extension and high accuracy.

  11. Source location in plates based on the multiple sensors array method and wavelet analysis

    International Nuclear Information System (INIS)

    Yang, Hong Jun; Shin, Tae Jin; Lee, Sang Kwon

    2014-01-01

    A new method for impact source localization in a plate is proposed based on the multiple signal classification (MUSIC) and wavelet analysis. For source localization, the direction of arrival of the wave caused by an impact on a plate and the distance between impact position and sensor should be estimated. The direction of arrival can be estimated accurately using MUSIC method. The distance can be obtained by using the time delay of arrival and the group velocity of the Lamb wave in a plate. Time delay is experimentally estimated using the continuous wavelet transform for the wave. The elasto dynamic theory is used for the group velocity estimation.

  12. Source location in plates based on the multiple sensors array method and wavelet analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hong Jun; Shin, Tae Jin; Lee, Sang Kwon [Inha University, Incheon (Korea, Republic of)

    2014-01-15

    A new method for impact source localization in a plate is proposed based on the multiple signal classification (MUSIC) and wavelet analysis. For source localization, the direction of arrival of the wave caused by an impact on a plate and the distance between impact position and sensor should be estimated. The direction of arrival can be estimated accurately using MUSIC method. The distance can be obtained by using the time delay of arrival and the group velocity of the Lamb wave in a plate. Time delay is experimentally estimated using the continuous wavelet transform for the wave. The elasto dynamic theory is used for the group velocity estimation.

  13. Comparison of variance estimators for metaanalysis of instrumental variable estimates

    NARCIS (Netherlands)

    Schmidt, A. F.; Hingorani, A. D.; Jefferis, B. J.; White, J.; Groenwold, R. H H; Dudbridge, F.; Ben-Shlomo, Y.; Chaturvedi, N.; Engmann, J.; Hughes, A.; Humphries, S.; Hypponen, E.; Kivimaki, M.; Kuh, D.; Kumari, M.; Menon, U.; Morris, R.; Power, C.; Price, J.; Wannamethee, G.; Whincup, P.

    2016-01-01

    Background: Mendelian randomization studies perform instrumental variable (IV) analysis using genetic IVs. Results of individual Mendelian randomization studies can be pooled through meta-analysis. We explored how different variance estimators influence the meta-analysed IV estimate. Methods: Two

  14. Introduction to variance estimation

    CERN Document Server

    Wolter, Kirk M

    2007-01-01

    We live in the information age. Statistical surveys are used every day to determine or evaluate public policy and to make important business decisions. Correct methods for computing the precision of the survey data and for making inferences to the target population are absolutely essential to sound decision making. Now in its second edition, Introduction to Variance Estimation has for more than twenty years provided the definitive account of the theory and methods for correct precision calculations and inference, including examples of modern, complex surveys in which the methods have been used successfully. The book provides instruction on the methods that are vital to data-driven decision making in business, government, and academe. It will appeal to survey statisticians and other scientists engaged in the planning and conduct of survey research, and to those analyzing survey data and charged with extracting compelling information from such data. It will appeal to graduate students and university faculty who...

  15. Estimating Discount Rates

    Directory of Open Access Journals (Sweden)

    Laurence Booth

    2015-04-01

    Full Text Available Discount rates are essential to applied finance, especially in setting prices for regulated utilities and valuing the liabilities of insurance companies and defined benefit pension plans. This paper reviews the basic building blocks for estimating discount rates. It also examines market risk premiums, as well as what constitutes a benchmark fair or required rate of return, in the aftermath of the financial crisis and the U.S. Federal Reserve’s bond-buying program. Some of the results are disconcerting. In Canada, utilities and pension regulators responded to the crash in different ways. Utilities regulators haven’t passed on the full impact of low interest rates, so that consumers face higher prices than they should whereas pension regulators have done the opposite, and forced some contributors to pay more. In both cases this is opposite to the desired effect of monetary policy which is to stimulate aggregate demand. A comprehensive survey of global finance professionals carried out last year provides some clues as to where adjustments are needed. In the U.S., the average equity market required return was estimated at 8.0 per cent; Canada’s is 7.40 per cent, due to the lower market risk premium and the lower risk-free rate. This paper adds a wealth of historic and survey data to conclude that the ideal base long-term interest rate used in risk premium models should be 4.0 per cent, producing an overall expected market return of 9-10.0 per cent. The same data indicate that allowed returns to utilities are currently too high, while the use of current bond yields in solvency valuations of pension plans and life insurers is unhelpful unless there is a realistic expectation that the plans will soon be terminated.

  16. Toxicity Estimation Software Tool (TEST)

    Science.gov (United States)

    The Toxicity Estimation Software Tool (TEST) was developed to allow users to easily estimate the toxicity of chemicals using Quantitative Structure Activity Relationships (QSARs) methodologies. QSARs are mathematical models used to predict measures of toxicity from the physical c...

  17. Sampling and estimating recreational use.

    Science.gov (United States)

    Timothy G. Gregoire; Gregory J. Buhyoff

    1999-01-01

    Probability sampling methods applicable to estimate recreational use are presented. Both single- and multiple-access recreation sites are considered. One- and two-stage sampling methods are presented. Estimation of recreational use is presented in a series of examples.

  18. Flexible and efficient estimating equations for variogram estimation

    KAUST Repository

    Sun, Ying; Chang, Xiaohui; Guan, Yongtao

    2018-01-01

    Variogram estimation plays a vastly important role in spatial modeling. Different methods for variogram estimation can be largely classified into least squares methods and likelihood based methods. A general framework to estimate the variogram through a set of estimating equations is proposed. This approach serves as an alternative approach to likelihood based methods and includes commonly used least squares approaches as its special cases. The proposed method is highly efficient as a low dimensional representation of the weight matrix is employed. The statistical efficiency of various estimators is explored and the lag effect is examined. An application to a hydrology dataset is also presented.

  19. Flexible and efficient estimating equations for variogram estimation

    KAUST Repository

    Sun, Ying

    2018-01-11

    Variogram estimation plays a vastly important role in spatial modeling. Different methods for variogram estimation can be largely classified into least squares methods and likelihood based methods. A general framework to estimate the variogram through a set of estimating equations is proposed. This approach serves as an alternative approach to likelihood based methods and includes commonly used least squares approaches as its special cases. The proposed method is highly efficient as a low dimensional representation of the weight matrix is employed. The statistical efficiency of various estimators is explored and the lag effect is examined. An application to a hydrology dataset is also presented.

  20. Improved Estimates of Thermodynamic Parameters

    Science.gov (United States)

    Lawson, D. D.

    1982-01-01

    Techniques refined for estimating heat of vaporization and other parameters from molecular structure. Using parabolic equation with three adjustable parameters, heat of vaporization can be used to estimate boiling point, and vice versa. Boiling points and vapor pressures for some nonpolar liquids were estimated by improved method and compared with previously reported values. Technique for estimating thermodynamic parameters should make it easier for engineers to choose among candidate heat-exchange fluids for thermochemical cycles.

  1. State estimation in networked systems

    NARCIS (Netherlands)

    Sijs, J.

    2012-01-01

    This thesis considers state estimation strategies for networked systems. State estimation refers to a method for computing the unknown state of a dynamic process by combining sensor measurements with predictions from a process model. The most well known method for state estimation is the Kalman

  2. Global Polynomial Kernel Hazard Estimation

    DEFF Research Database (Denmark)

    Hiabu, Munir; Miranda, Maria Dolores Martínez; Nielsen, Jens Perch

    2015-01-01

    This paper introduces a new bias reducing method for kernel hazard estimation. The method is called global polynomial adjustment (GPA). It is a global correction which is applicable to any kernel hazard estimator. The estimator works well from a theoretical point of view as it asymptotically redu...

  3. Uveal melanoma: Estimating prognosis

    Directory of Open Access Journals (Sweden)

    Swathi Kaliki

    2015-01-01

    Full Text Available Uveal melanoma is the most common primary malignant tumor of the eye in adults, predominantly found in Caucasians. Local tumor control of uveal melanoma is excellent, yet this malignancy is associated with relatively high mortality secondary to metastasis. Various clinical, histopathological, cytogenetic features and gene expression features help in estimating the prognosis of uveal melanoma. The clinical features associated with poor prognosis in patients with uveal melanoma include older age at presentation, male gender, larger tumor basal diameter and thickness, ciliary body location, diffuse tumor configuration, association with ocular/oculodermal melanocytosis, extraocular tumor extension, and advanced tumor staging by American Joint Committee on Cancer classification. Histopathological features suggestive of poor prognosis include epithelioid cell type, high mitotic activity, higher values of mean diameter of ten largest nucleoli, higher microvascular density, extravascular matrix patterns, tumor-infiltrating lymphocytes, tumor-infiltrating macrophages, higher expression of insulin-like growth factor-1 receptor, and higher expression of human leukocyte antigen Class I and II. Monosomy 3, 1p loss, 6q loss, and 8q and those classified as Class II by gene expression are predictive of poor prognosis of uveal melanoma. In this review, we discuss the prognostic factors of uveal melanoma. A database search was performed on PubMed, using the terms "uvea," "iris," "ciliary body," "choroid," "melanoma," "uveal melanoma" and "prognosis," "metastasis," "genetic testing," "gene expression profiling." Relevant English language articles were extracted, reviewed, and referenced appropriately.

  4. Approaches to estimating decommissioning costs

    International Nuclear Information System (INIS)

    Smith, R.I.

    1990-07-01

    The chronological development of methodology for estimating the cost of nuclear reactor power station decommissioning is traced from the mid-1970s through 1990. Three techniques for developing decommissioning cost estimates are described. The two viable techniques are compared by examining estimates developed for the same nuclear power station using both methods. The comparison shows that the differences between the estimates are due largely to differing assumptions regarding the size of the utility and operating contractor overhead staffs. It is concluded that the two methods provide bounding estimates on a range of manageable costs, and provide reasonable bases for the utility rate adjustments necessary to pay for future decommissioning costs. 6 refs

  5. Estimating Stochastic Volatility Models using Prediction-based Estimating Functions

    DEFF Research Database (Denmark)

    Lunde, Asger; Brix, Anne Floor

    to the performance of the GMM estimator based on conditional moments of integrated volatility from Bollerslev and Zhou (2002). The case where the observed log-price process is contaminated by i.i.d. market microstructure (MMS) noise is also investigated. First, the impact of MMS noise on the parameter estimates from......In this paper prediction-based estimating functions (PBEFs), introduced in Sørensen (2000), are reviewed and PBEFs for the Heston (1993) stochastic volatility model are derived. The finite sample performance of the PBEF based estimator is investigated in a Monte Carlo study, and compared...... to correctly account for the noise are investigated. Our Monte Carlo study shows that the estimator based on PBEFs outperforms the GMM estimator, both in the setting with and without MMS noise. Finally, an empirical application investigates the possible challenges and general performance of applying the PBEF...

  6. Studying Room Acoustics using a Monopole-Dipole Microphone Array

    Science.gov (United States)

    Begault, Durand R.; Abel, Jonathan S.; Gills, Stephen R. (Technical Monitor)

    1997-01-01

    The use of a soundfield microphone for examining the directional nature of a room impulse response was reported recently. By cross-correlating monopole and co-located dipole microphone signals aligned with left-right, up-down, and front-back axes, a sense of signal direction of arrival is revealed. The current study is concerned with the array's ability to detect individual reflections and directions of arrival, as a function of the cross-correlation window duration. If is window is too long, weak reflections are overlooked; if too short, spurious detections result. Guidelines are presented for setting the window width according to perceptual criteria. Formulas are presented describing the accuracy with which direction of arrival can be estimated as a function of room specifics and measurement noise. The direction of arrival of early reflections is more accurately determined than that of later reflections which are quieter and more numerous. The transition from a fairly directional sound field at the beginning of the room impulse response to a uni-directional diffuse field is examined. Finally, it is shown that measurements from additional dipole orientations can significantly improve the ability to detect reflections and estimate their directions of arrival.

  7. A new estimator for vector velocity estimation [medical ultrasonics

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2001-01-01

    A new estimator for determining the two-dimensional velocity vector using a pulsed ultrasound field is derived. The estimator uses a transversely modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation...... be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce the influence of a spatial velocity spread. Examples for different velocity vectors and field conditions are shown using both simple and more complex field simulations. A relative accuracy of 10.1% is obtained...

  8. Estimation of Water Quality

    International Nuclear Information System (INIS)

    Vetrinskaya, N.I.; Manasbayeva, A.B.

    1998-01-01

    Water has a particular ecological function and it is an indicator of the general state of the biosphere. In relation with this summary, the toxicological evaluation of water by biologic testing methods is very actual. The peculiarity of biologic testing information is an integral reflection of all totality properties of examination of the environment in position of its perception by living objects. Rapid integral evaluation of anthropological situation is a base aim of biologic testing. If this evaluation has deviations from normal state, detailed analysis and revelation of dangerous components could be conducted later. The quality of water from the Degelen gallery, where nuclear explosions were conducted, was investigated by bio-testing methods. The micro-organisms (Micrococcus Luteus, Candida crusei, Pseudomonas algaligenes) and water plant elodea (Elodea canadensis Rich) were used as test-objects. It is known that the transporting functions of cell membranes of living organisms are violated the first time in extreme conditions by difference influences. Therefore, ion penetration of elodeas and micro-organisms cells, which contained in the examination water with toxicants, were used as test-function. Alteration of membrane penetration was estimated by measurement of electrolytes electrical conductivity, which gets out from living objects cells to distillate water. Index of water toxic is ratio of electrical conductivity in experience to electrical conductivity in control. Also, observations from common state of plant, which was incubated in toxic water, were made. (Chronic experience conducted for 60 days.) The plants were incubated in water samples, which were picked out from gallery in the years 1996 and 1997. The time of incubation is 1-10 days. The results of investigation showed that ion penetration of elodeas and micro-organisms cells changed very much with influence of radionuclides, which were contained in testing water. Changes are taking place even in

  9. WAYS HIERARCHY OF ACCOUNTING ESTIMATES

    Directory of Open Access Journals (Sweden)

    ŞERBAN CLAUDIU VALENTIN

    2015-03-01

    Full Text Available Based on one hand on the premise that the estimate is an approximate evaluation, completed with the fact that the term estimate is increasingly common and used by a variety of both theoretical and practical areas, particularly in situations where we can not decide ourselves with certainty, it must be said that, in fact, we are dealing with estimates and in our case with an accounting estimate. Completing on the other hand the idea above with the phrase "estimated value", which implies that we are dealing with a value obtained from an evaluation process, but its size is not exact but approximated, meaning is close to the actual size, it becomes obvious the neccessity to delimit the hierarchical relationship between evaluation / estimate while considering the context in which the evaluation activity is derulated at entity level.

  10. Spring Small Grains Area Estimation

    Science.gov (United States)

    Palmer, W. F.; Mohler, R. J.

    1986-01-01

    SSG3 automatically estimates acreage of spring small grains from Landsat data. Report describes development and testing of a computerized technique for using Landsat multispectral scanner (MSS) data to estimate acreage of spring small grains (wheat, barley, and oats). Application of technique to analysis of four years of data from United States and Canada yielded estimates of accuracy comparable to those obtained through procedures that rely on trained analysis.

  11. Parameter estimation in plasmonic QED

    Science.gov (United States)

    Jahromi, H. Rangani

    2018-03-01

    We address the problem of parameter estimation in the presence of plasmonic modes manipulating emitted light via the localized surface plasmons in a plasmonic waveguide at the nanoscale. The emitter that we discuss is the nitrogen vacancy centre (NVC) in diamond modelled as a qubit. Our goal is to estimate the β factor measuring the fraction of emitted energy captured by waveguide surface plasmons. The best strategy to obtain the most accurate estimation of the parameter, in terms of the initial state of the probes and different control parameters, is investigated. In particular, for two-qubit estimation, it is found although we may achieve the best estimation at initial instants by using the maximally entangled initial states, at long times, the optimal estimation occurs when the initial state of the probes is a product one. We also find that decreasing the interqubit distance or increasing the propagation length of the plasmons improve the precision of the estimation. Moreover, decrease of spontaneous emission rate of the NVCs retards the quantum Fisher information (QFI) reduction and therefore the vanishing of the QFI, measuring the precision of the estimation, is delayed. In addition, if the phase parameter of the initial state of the two NVCs is equal to πrad, the best estimation with the two-qubit system is achieved when initially the NVCs are maximally entangled. Besides, the one-qubit estimation has been also analysed in detail. Especially, we show that, using a two-qubit probe, at any arbitrary time, enhances considerably the precision of estimation in comparison with one-qubit estimation.

  12. Fatores que facilitam e dificultam a entrevista familiar no processo de doação de órgãos e tecidos para transplante Factores que facilitan y dificultan la entrevista familiar en el proceso de donación de órganos y tejidos para transplante Factors that facilitate and hinder family interviews in the process of donating organs and tissues for transplantation

    Directory of Open Access Journals (Sweden)

    Marcelo José dos Santos

    2011-01-01

    Full Text Available OBJETIVO: Desvelar a percepção dos profissionais que atuam em Organizações de Procura de Órgãos sobre os fatores que facilitam e dificultam a entrevista familiar no processo de doação de órgãos e tecidos para transplante. MÉTODOS: Trata-se de pesquisa qualitativa, na vertente fenomenológica, modalidade "estrutura do fenômeno situado". Participaram do estudo 18 profissionais que atuavam em Organizações de Procura de Órgãos. RESULTADOS: Após a análise das entrevistas, foram revelados os fatores que facilitam e dificultam a entrevista familiar. CONCLUSÃO: As proposições que emergiram, revelaram que os fatores que facilitam e dificultam a entrevista familiar estão relacionados ao local da entrevista, à assistência prestada ao potencial doador e aos familiares, aos esclarecimentos fornecidos à família e a manifestação do potencial doador em vida sobre a decisão quanto à doação de órgãos.OBJETIVO: Develar la percepción de los profesionales que actúan en Organizaciones de Búsqueda de Órganos sobre los factores que facilitan y dificultan la entrevista familiar en el proceso de donación de órganos y tejidos para transplante. MÉTODOS: Se trata de una investigación cualitativa, en la vertiente fenomenológica, modalidad "estructura del fenómeno situado". Participaron en el estudio 18 profesionales que actuaban en Organizaciones de Búsqueda de Órganos. RESULTADOS: Después del análisis de las entrevistas, fueron revelados los factores que facilitan y dificultan la entrevista familiar. CONCLUSIÓN: Las proposiciones que emergieron, revelaron que los factores que facilitan y dificultan la entrevista familiar están relacionados al local de la entrevista, a la asistencia prestada al donador en potencia y a los familiares, a las aclaraciones dadas a la familia y la manifestación del potencial donador, en vida, sobre su decisión respecto a la donación de órganos.OBJECTIVE: To unveil the perceptions of

  13. Quantity Estimation Of The Interactions

    International Nuclear Information System (INIS)

    Gorana, Agim; Malkaj, Partizan; Muda, Valbona

    2007-01-01

    In this paper we present some considerations about quantity estimations, regarding the range of interaction and the conservations laws in various types of interactions. Our estimations are done under classical and quantum point of view and have to do with the interaction's carriers, the radius, the influence range and the intensity of interactions

  14. CONDITIONS FOR EXACT CAVALIERI ESTIMATION

    Directory of Open Access Journals (Sweden)

    Mónica Tinajero-Bravo

    2014-03-01

    Full Text Available Exact Cavalieri estimation amounts to zero variance estimation of an integral with systematic observations along a sampling axis. A sufficient condition is given, both in the continuous and the discrete cases, for exact Cavalieri sampling. The conclusions suggest improvements on the current stereological application of fractionator-type sampling.

  15. Optimization of Barron density estimates

    Czech Academy of Sciences Publication Activity Database

    Vajda, Igor; van der Meulen, E. C.

    2001-01-01

    Roč. 47, č. 5 (2001), s. 1867-1883 ISSN 0018-9448 R&D Projects: GA ČR GA102/99/1137 Grant - others:Copernicus(XE) 579 Institutional research plan: AV0Z1075907 Keywords : Barron estimator * chi-square criterion * density estimation Subject RIV: BD - Theory of Information Impact factor: 2.077, year: 2001

  16. Stochastic Estimation via Polynomial Chaos

    Science.gov (United States)

    2015-10-01

    AFRL-RW-EG-TR-2015-108 Stochastic Estimation via Polynomial Chaos Douglas V. Nance Air Force Research...COVERED (From - To) 20-04-2015 – 07-08-2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Stochastic Estimation via Polynomial Chaos ...This expository report discusses fundamental aspects of the polynomial chaos method for representing the properties of second order stochastic

  17. Bayesian estimates of linkage disequilibrium

    Directory of Open Access Journals (Sweden)

    Abad-Grau María M

    2007-06-01

    Full Text Available Abstract Background The maximum likelihood estimator of D' – a standard measure of linkage disequilibrium – is biased toward disequilibrium, and the bias is particularly evident in small samples and rare haplotypes. Results This paper proposes a Bayesian estimation of D' to address this problem. The reduction of the bias is achieved by using a prior distribution on the pair-wise associations between single nucleotide polymorphisms (SNPs that increases the likelihood of equilibrium with increasing physical distances between pairs of SNPs. We show how to compute the Bayesian estimate using a stochastic estimation based on MCMC methods, and also propose a numerical approximation to the Bayesian estimates that can be used to estimate patterns of LD in large datasets of SNPs. Conclusion Our Bayesian estimator of D' corrects the bias toward disequilibrium that affects the maximum likelihood estimator. A consequence of this feature is a more objective view about the extent of linkage disequilibrium in the human genome, and a more realistic number of tagging SNPs to fully exploit the power of genome wide association studies.

  18. Reactivity estimation using digital nonlinear H∞ estimator for VHTRC experiment

    International Nuclear Information System (INIS)

    Suzuki, Katsuo; Nabeshima, Kunihiko; Yamane, Tsuyoshi

    2003-01-01

    On-line and real-time estimation of time-varying reactivity in a nuclear reactor in necessary for early detection of reactivity anomaly and safe operation. Using a digital nonlinear H ∞ estimator, an experiment of real-time dynamic reactivity estimation was carried out in the Very High Temperature Reactor Critical Assembly (VHTRC) of Japan Atomic Energy Research Institute. Some technical issues of the experiment are described, such as reactivity insertion, data sampling frequency, anti-aliasing filter, experimental circuit and digitalising nonlinear H ∞ reactivity estimator, and so on. Then, we discussed the experimental results obtained by the digital nonlinear H ∞ estimator with sampled data of the nuclear instrumentation signal for the power responses under various reactivity insertions. Good performances of estimated reactivity were observed, with almost no delay to the true reactivity and sufficient accuracy between 0.05 cent and 0.1 cent. The experiment shows that real-time reactivity for data sampling period of 10 ms can be certainly realized. From the results of the experiment, it is concluded that the digital nonlinear H ∞ reactivity estimator can be applied as on-line real-time reactivity meter for actual nuclear plants. (author)

  19. Age estimation in the living

    DEFF Research Database (Denmark)

    Tangmose, Sara; Thevissen, Patrick; Lynnerup, Niels

    2015-01-01

    A radiographic assessment of third molar development is essential for differentiating between juveniles and adolescents in forensic age estimations. As the developmental stages of third molars are highly correlated, age estimates based on a combination of a full set of third molar scores...... are statistically complicated. Transition analysis (TA) is a statistical method developed for estimating age at death in skeletons, which combines several correlated developmental traits into one age estimate including a 95% prediction interval. The aim of this study was to evaluate the performance of TA...... in the living on a full set of third molar scores. A cross sectional sample of 854 panoramic radiographs, homogenously distributed by sex and age (15.0-24.0 years), were randomly split in two; a reference sample for obtaining age estimates including a 95% prediction interval according to TA; and a validation...

  20. UNBIASED ESTIMATORS OF SPECIFIC CONNECTIVITY

    Directory of Open Access Journals (Sweden)

    Jean-Paul Jernot

    2011-05-01

    Full Text Available This paper deals with the estimation of the specific connectivity of a stationary random set in IRd. It turns out that the "natural" estimator is only asymptotically unbiased. The example of a boolean model of hypercubes illustrates the amplitude of the bias produced when the measurement field is relatively small with respect to the range of the random set. For that reason unbiased estimators are desired. Such an estimator can be found in the literature in the case where the measurement field is a right parallelotope. In this paper, this estimator is extended to apply to measurement fields of various shapes, and to possess a smaller variance. Finally an example from quantitative metallography (specific connectivity of a population of sintered bronze particles is given.

  1. Laser cost experience and estimation

    International Nuclear Information System (INIS)

    Shofner, F.M.; Hoglund, R.L.

    1977-01-01

    This report addresses the question of estimating the capital and operating costs for LIS (Laser Isotope Separation) lasers, which have performance requirements well beyond the state of mature art. This question is seen with different perspectives by political leaders, ERDA administrators, scientists, and engineers concerned with reducing LIS to economically successful commercial practice, on a timely basis. Accordingly, this report attempts to provide ''ballpark'' estimators for capital and operating costs and useful design and operating information for lasers based on mature technology, and their LIS analogs. It is written very basically and is intended to respond about equally to the perspectives of administrators, scientists, and engineers. Its major contributions are establishing the current, mature, industrialized laser track record (including capital and operating cost estimators, reliability, types of application, etc.) and, especially, evolution of generalized estimating procedures for capital and operating cost estimators for new laser design

  2. Estimation of toxicity using the Toxicity Estimation Software Tool (TEST)

    Science.gov (United States)

    Tens of thousands of chemicals are currently in commerce, and hundreds more are introduced every year. Since experimental measurements of toxicity are extremely time consuming and expensive, it is imperative that alternative methods to estimate toxicity are developed.

  3. Infrasonic detection performance in presence of nuisance signal

    Science.gov (United States)

    Charbit, Maurice; Arrowsmith, Stephen; Che, Il-young; Le Pichon, Alexis; Nouvellet, Adrien; Park, Junghyun; Roueff, Francois

    2014-05-01

    The infrasound network of the International Monitoring System (IMS) consists of sixty stations deployed all over the World by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The IMS has been designed to reliably detect, at least by two stations, an explosion greater than 1 kiloton located anywhere on the Earth [1]. Each station is an array of at least four microbarometers with an aperture of 1 to 3 km. The first important issue is to detect the presence of the signal of interest (SOI) embedded in noise. The detector is commonly based on the property that the SOI provides coherent observations on the sensors but not the noise. The statistic of test, called F-stat [2], [5], [6] , calculated in a time cell a few seconds, is commonly used for this purpose. In this paper, we assume that a coherent source is permanently present arriving from an unknown direction of arrivals (DOA). The typical case is the presence of microbaroms or the presence of wind. This source is seen as a nuisance signal (NS). In [4], [3] authors assume that a time cell without the SOI (CH0) is available, whereas a following time cell is considered as the cell under test (CUT). Therefore the DOA and the SNR of the NS can be estimated. If the signal-to-noise ration SNR of the NS is large enough, the distribution of the F-stat under the absence of SOI is known to be a non central Fisher. It follows that the threshold can be performed from a given value of the FAR. The major drawback to keep the NS is that the NS could hide the SOI, this phenomena is similar to the leakage which is a well-known phenomena in the Fourier analysis. An other approach consists to use the DOA estimate of the NS to mitigate the NS by spatial notch filter in the frequency domain. On this approach a new algorithm is provided. To illustrate, numerical results on synthetical and real data are presented, in term of Receiver Operating Characteristic ROC curves. REFERENCES [1] Christie D.R. and Campus P., The IMS

  4. Condition Number Regularized Covariance Estimation.

    Science.gov (United States)

    Won, Joong-Ho; Lim, Johan; Kim, Seung-Jean; Rajaratnam, Bala

    2013-06-01

    Estimation of high-dimensional covariance matrices is known to be a difficult problem, has many applications, and is of current interest to the larger statistics community. In many applications including so-called the "large p small n " setting, the estimate of the covariance matrix is required to be not only invertible, but also well-conditioned. Although many regularization schemes attempt to do this, none of them address the ill-conditioning problem directly. In this paper, we propose a maximum likelihood approach, with the direct goal of obtaining a well-conditioned estimator. No sparsity assumption on either the covariance matrix or its inverse are are imposed, thus making our procedure more widely applicable. We demonstrate that the proposed regularization scheme is computationally efficient, yields a type of Steinian shrinkage estimator, and has a natural Bayesian interpretation. We investigate the theoretical properties of the regularized covariance estimator comprehensively, including its regularization path, and proceed to develop an approach that adaptively determines the level of regularization that is required. Finally, we demonstrate the performance of the regularized estimator in decision-theoretic comparisons and in the financial portfolio optimization setting. The proposed approach has desirable properties, and can serve as a competitive procedure, especially when the sample size is small and when a well-conditioned estimator is required.

  5. Condition Number Regularized Covariance Estimation*

    Science.gov (United States)

    Won, Joong-Ho; Lim, Johan; Kim, Seung-Jean; Rajaratnam, Bala

    2012-01-01

    Estimation of high-dimensional covariance matrices is known to be a difficult problem, has many applications, and is of current interest to the larger statistics community. In many applications including so-called the “large p small n” setting, the estimate of the covariance matrix is required to be not only invertible, but also well-conditioned. Although many regularization schemes attempt to do this, none of them address the ill-conditioning problem directly. In this paper, we propose a maximum likelihood approach, with the direct goal of obtaining a well-conditioned estimator. No sparsity assumption on either the covariance matrix or its inverse are are imposed, thus making our procedure more widely applicable. We demonstrate that the proposed regularization scheme is computationally efficient, yields a type of Steinian shrinkage estimator, and has a natural Bayesian interpretation. We investigate the theoretical properties of the regularized covariance estimator comprehensively, including its regularization path, and proceed to develop an approach that adaptively determines the level of regularization that is required. Finally, we demonstrate the performance of the regularized estimator in decision-theoretic comparisons and in the financial portfolio optimization setting. The proposed approach has desirable properties, and can serve as a competitive procedure, especially when the sample size is small and when a well-conditioned estimator is required. PMID:23730197

  6. Radiation dose estimates for radiopharmaceuticals

    International Nuclear Information System (INIS)

    Stabin, M.G.; Stubbs, J.B.; Toohey, R.E.

    1996-04-01

    Tables of radiation dose estimates based on the Cristy-Eckerman adult male phantom are provided for a number of radiopharmaceuticals commonly used in nuclear medicine. Radiation dose estimates are listed for all major source organs, and several other organs of interest. The dose estimates were calculated using the MIRD Technique as implemented in the MIRDOSE3 computer code, developed by the Oak Ridge Institute for Science and Education, Radiation Internal Dose Information Center. In this code, residence times for source organs are used with decay data from the MIRD Radionuclide Data and Decay Schemes to produce estimates of radiation dose to organs of standardized phantoms representing individuals of different ages. The adult male phantom of the Cristy-Eckerman phantom series is different from the MIRD 5, or Reference Man phantom in several aspects, the most important of which is the difference in the masses and absorbed fractions for the active (red) marrow. The absorbed fractions for flow energy photons striking the marrow are also different. Other minor differences exist, but are not likely to significantly affect dose estimates calculated with the two phantoms. Assumptions which support each of the dose estimates appears at the bottom of the table of estimates for a given radiopharmaceutical. In most cases, the model kinetics or organ residence times are explicitly given. The results presented here can easily be extended to include other radiopharmaceuticals or phantoms

  7. Risk estimation using probability machines

    Science.gov (United States)

    2014-01-01

    Background Logistic regression has been the de facto, and often the only, model used in the description and analysis of relationships between a binary outcome and observed features. It is widely used to obtain the conditional probabilities of the outcome given predictors, as well as predictor effect size estimates using conditional odds ratios. Results We show how statistical learning machines for binary outcomes, provably consistent for the nonparametric regression problem, can be used to provide both consistent conditional probability estimation and conditional effect size estimates. Effect size estimates from learning machines leverage our understanding of counterfactual arguments central to the interpretation of such estimates. We show that, if the data generating model is logistic, we can recover accurate probability predictions and effect size estimates with nearly the same efficiency as a correct logistic model, both for main effects and interactions. We also propose a method using learning machines to scan for possible interaction effects quickly and efficiently. Simulations using random forest probability machines are presented. Conclusions The models we propose make no assumptions about the data structure, and capture the patterns in the data by just specifying the predictors involved and not any particular model structure. So they do not run the same risks of model mis-specification and the resultant estimation biases as a logistic model. This methodology, which we call a “risk machine”, will share properties from the statistical machine that it is derived from. PMID:24581306

  8. Boundary methods for mode estimation

    Science.gov (United States)

    Pierson, William E., Jr.; Ulug, Batuhan; Ahalt, Stanley C.

    1999-08-01

    This paper investigates the use of Boundary Methods (BMs), a collection of tools used for distribution analysis, as a method for estimating the number of modes associated with a given data set. Model order information of this type is required by several pattern recognition applications. The BM technique provides a novel approach to this parameter estimation problem and is comparable in terms of both accuracy and computations to other popular mode estimation techniques currently found in the literature and automatic target recognition applications. This paper explains the methodology used in the BM approach to mode estimation. Also, this paper quickly reviews other common mode estimation techniques and describes the empirical investigation used to explore the relationship of the BM technique to other mode estimation techniques. Specifically, the accuracy and computational efficiency of the BM technique are compared quantitatively to the a mixture of Gaussian (MOG) approach and a k-means approach to model order estimation. The stopping criteria of the MOG and k-means techniques is the Akaike Information Criteria (AIC).

  9. Generalized Centroid Estimators in Bioinformatics

    Science.gov (United States)

    Hamada, Michiaki; Kiryu, Hisanori; Iwasaki, Wataru; Asai, Kiyoshi

    2011-01-01

    In a number of estimation problems in bioinformatics, accuracy measures of the target problem are usually given, and it is important to design estimators that are suitable to those accuracy measures. However, there is often a discrepancy between an employed estimator and a given accuracy measure of the problem. In this study, we introduce a general class of efficient estimators for estimation problems on high-dimensional binary spaces, which represent many fundamental problems in bioinformatics. Theoretical analysis reveals that the proposed estimators generally fit with commonly-used accuracy measures (e.g. sensitivity, PPV, MCC and F-score) as well as it can be computed efficiently in many cases, and cover a wide range of problems in bioinformatics from the viewpoint of the principle of maximum expected accuracy (MEA). It is also shown that some important algorithms in bioinformatics can be interpreted in a unified manner. Not only the concept presented in this paper gives a useful framework to design MEA-based estimators but also it is highly extendable and sheds new light on many problems in bioinformatics. PMID:21365017

  10. NASA Software Cost Estimation Model: An Analogy Based Estimation Model

    Science.gov (United States)

    Hihn, Jairus; Juster, Leora; Menzies, Tim; Mathew, George; Johnson, James

    2015-01-01

    The cost estimation of software development activities is increasingly critical for large scale integrated projects such as those at DOD and NASA especially as the software systems become larger and more complex. As an example MSL (Mars Scientific Laboratory) developed at the Jet Propulsion Laboratory launched with over 2 million lines of code making it the largest robotic spacecraft ever flown (Based on the size of the software). Software development activities are also notorious for their cost growth, with NASA flight software averaging over 50% cost growth. All across the agency, estimators and analysts are increasingly being tasked to develop reliable cost estimates in support of program planning and execution. While there has been extensive work on improving parametric methods there is very little focus on the use of models based on analogy and clustering algorithms. In this paper we summarize our findings on effort/cost model estimation and model development based on ten years of software effort estimation research using data mining and machine learning methods to develop estimation models based on analogy and clustering. The NASA Software Cost Model performance is evaluated by comparing it to COCOMO II, linear regression, and K-­ nearest neighbor prediction model performance on the same data set.

  11. Likelihood estimators for multivariate extremes

    KAUST Repository

    Huser, Raphaë l; Davison, Anthony C.; Genton, Marc G.

    2015-01-01

    The main approach to inference for multivariate extremes consists in approximating the joint upper tail of the observations by a parametric family arising in the limit for extreme events. The latter may be expressed in terms of componentwise maxima, high threshold exceedances or point processes, yielding different but related asymptotic characterizations and estimators. The present paper clarifies the connections between the main likelihood estimators, and assesses their practical performance. We investigate their ability to estimate the extremal dependence structure and to predict future extremes, using exact calculations and simulation, in the case of the logistic model.

  12. Likelihood estimators for multivariate extremes

    KAUST Repository

    Huser, Raphaël

    2015-11-17

    The main approach to inference for multivariate extremes consists in approximating the joint upper tail of the observations by a parametric family arising in the limit for extreme events. The latter may be expressed in terms of componentwise maxima, high threshold exceedances or point processes, yielding different but related asymptotic characterizations and estimators. The present paper clarifies the connections between the main likelihood estimators, and assesses their practical performance. We investigate their ability to estimate the extremal dependence structure and to predict future extremes, using exact calculations and simulation, in the case of the logistic model.

  13. Analytical estimates of structural behavior

    CERN Document Server

    Dym, Clive L

    2012-01-01

    Explicitly reintroducing the idea of modeling to the analysis of structures, Analytical Estimates of Structural Behavior presents an integrated approach to modeling and estimating the behavior of structures. With the increasing reliance on computer-based approaches in structural analysis, it is becoming even more important for structural engineers to recognize that they are dealing with models of structures, not with the actual structures. As tempting as it is to run innumerable simulations, closed-form estimates can be effectively used to guide and check numerical results, and to confirm phys

  14. Phase estimation in optical interferometry

    CERN Document Server

    Rastogi, Pramod

    2014-01-01

    Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre

  15. Greenhouse gas emission rate estimates from airborne remote sensing in the short-wave infrared

    Energy Technology Data Exchange (ETDEWEB)

    Krings, Thomas

    2013-01-30

    The quantification of emissions of the greenhouse gases carbon dioxide (CO{sub 2}) and methane (CH{sub 4}) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of CO{sub 2} and CH{sub 4} is the optical remote sensing instrument MAMAP, operated from aircraft. With a ground scene size of the order of 50m and a relative accuracy of the column-averaged dry air mole fractions of about 0.3% for XCO{sub 2} and less than 0.4% for XCH{sub 4}, MAMAP can make a significant contribution in this respect. Detailed sensitivity studies showed that the modified WFM-DOAS retrieval algorithm used for MAMAP has an approximate accuracy of about 0.24% for XCH{sub 4} and XCO{sub 2} in typical atmospheric conditions. At the example of CO{sub 2} plumes from two different power plants and CH{sub 4} plumes from coal mine ventilation shafts, two inversion approaches to obtain emission rates were developed and tested. One is based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data and the other is based on a simple Gaussian integral method. Compared to CO{sub 2} emission estimates as reported by the power plants' operator within the framework of emission databases (24 and 13 MtCO{sub 2} yr{sup -1}), the results of the individual inversion techniques were within ±10% with uncertainties of ±20-30% mainly due to insufficient wind information and non-stationary atmospheric conditions. Measurements at the coal mine included on-site wind observations by an aircraft turbulence probe that could be utilised to calibrate the wind model. In this case, the inversion results have a bias of less than 1

  16. An Analytical Cost Estimation Procedure

    National Research Council Canada - National Science Library

    Jayachandran, Toke

    1999-01-01

    Analytical procedures that can be used to do a sensitivity analysis of a cost estimate, and to perform tradeoffs to identify input values that can reduce the total cost of a project, are described in the report...

  17. Spectral unmixing: estimating partial abundances

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2009-01-01

    Full Text Available techniques is complicated when considering very similar spectral signatures. Iron-bearing oxide/hydroxide/sulfate minerals have similar spectral signatures. The study focuses on how could estimates of abundances of spectrally similar iron-bearing oxide...

  18. 50th Percentile Rent Estimates

    Data.gov (United States)

    Department of Housing and Urban Development — Rent estimates at the 50th percentile (or median) are calculated for all Fair Market Rent areas. Fair Market Rents (FMRs) are primarily used to determine payment...

  19. LPS Catch and Effort Estimation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data collected from the LPS dockside (LPIS) and the LPS telephone (LPTS) surveys are combined to produce estimates of total recreational catch, landings, and fishing...

  20. Exploratory shaft liner corrosion estimate

    International Nuclear Information System (INIS)

    Duncan, D.R.

    1985-10-01

    An estimate of expected corrosion degradation during the 100-year design life of the Exploratory Shaft (ES) is presented. The basis for the estimate is a brief literature survey of corrosion data, in addition to data taken by the Basalt Waste Isolation Project. The scope of the study is expected corrosion environment of the ES, the corrosion modes of general corrosion, pitting and crevice corrosion, dissimilar metal corrosion, and environmentally assisted cracking. The expected internal and external environment of the shaft liner is described in detail and estimated effects of each corrosion mode are given. The maximum amount of general corrosion degradation was estimated to be 70 mils at the exterior and 48 mils at the interior, at the shaft bottom. Corrosion at welds or mechanical joints could be significant, dependent on design. After a final determination of corrosion allowance has been established by the project it will be added to the design criteria. 10 refs., 6 figs., 5 tabs

  1. Project Cost Estimation for Planning

    Science.gov (United States)

    2010-02-26

    For Nevada Department of Transportation (NDOT), there are far too many projects that ultimately cost much more than initially planned. Because project nominations are linked to estimates of future funding and the analysis of system needs, the inaccur...

  2. Robust estimation and hypothesis testing

    CERN Document Server

    Tiku, Moti L

    2004-01-01

    In statistical theory and practice, a certain distribution is usually assumed and then optimal solutions sought. Since deviations from an assumed distribution are very common, one cannot feel comfortable with assuming a particular distribution and believing it to be exactly correct. That brings the robustness issue in focus. In this book, we have given statistical procedures which are robust to plausible deviations from an assumed mode. The method of modified maximum likelihood estimation is used in formulating these procedures. The modified maximum likelihood estimators are explicit functions of sample observations and are easy to compute. They are asymptotically fully efficient and are as efficient as the maximum likelihood estimators for small sample sizes. The maximum likelihood estimators have computational problems and are, therefore, elusive. A broad range of topics are covered in this book. Solutions are given which are easy to implement and are efficient. The solutions are also robust to data anomali...

  3. Estimating Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Jørgensen, Morten W.; Sorenson, Spencer C.

    1998-01-01

    Several parameters of importance for estimating emissions from railway traffic are discussed, and typical results presented. Typical emissions factors from diesel engines and electrical power generation are presented, and the effect of differences in national electrical generation sources...

  4. Travel time estimation using Bluetooth.

    Science.gov (United States)

    2015-06-01

    The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detection System (BPDS) to : estimate travel time in an urban area. Specifically, the study investigated the possibility of measuring overall congestion, the : ...

  5. Estimating uncertainty in resolution tests

    CSIR Research Space (South Africa)

    Goncalves, DP

    2006-05-01

    Full Text Available frequencies yields a biased estimate, and we provide an improved estimator. An application illustrates how the results derived can be incorporated into a larger un- certainty analysis. ? 2006 Society of Photo-Optical Instrumentation Engineers. H20851DOI: 10....1117/1.2202914H20852 Subject terms: resolution testing; USAF 1951 test target; resolution uncertainity. Paper 050404R received May 20, 2005; revised manuscript received Sep. 2, 2005; accepted for publication Sep. 9, 2005; published online May 10, 2006. 1...

  6. Estimating solar radiation in Ghana

    International Nuclear Information System (INIS)

    Anane-Fenin, K.

    1986-04-01

    The estimates of global radiation on a horizontal surface for 9 towns in Ghana, West Africa, are deduced from their sunshine data using two methods developed by Angstrom and Sabbagh. An appropriate regional parameter is determined with the first method and used to predict solar irradiation in all the 9 stations with an accuracy better than 15%. Estimation of diffuse solar irradiation by Page, Lin and Jordan and three other authors' correlation are performed and the results examined. (author)

  7. The Psychology of Cost Estimating

    Science.gov (United States)

    Price, Andy

    2016-01-01

    Cost estimation for large (and even not so large) government programs is a challenge. The number and magnitude of cost overruns associated with large Department of Defense (DoD) and National Aeronautics and Space Administration (NASA) programs highlight the difficulties in developing and promulgating accurate cost estimates. These overruns can be the result of inadequate technology readiness or requirements definition, the whims of politicians or government bureaucrats, or even as failures of the cost estimating profession itself. However, there may be another reason for cost overruns that is right in front of us, but only recently have we begun to grasp it: the fact that cost estimators and their customers are human. The last 70+ years of research into human psychology and behavioral economics have yielded amazing findings into how we humans process and use information to make judgments and decisions. What these scientists have uncovered is surprising: humans are often irrational and illogical beings, making decisions based on factors such as emotion and perception, rather than facts and data. These built-in biases to our thinking directly affect how we develop our cost estimates and how those cost estimates are used. We cost estimators can use this knowledge of biases to improve our cost estimates and also to improve how we communicate and work with our customers. By understanding how our customers think, and more importantly, why they think the way they do, we can have more productive relationships and greater influence. By using psychology to our advantage, we can more effectively help the decision maker and our organizations make fact-based decisions.

  8. Estimating emissions from railway traffic

    Energy Technology Data Exchange (ETDEWEB)

    Joergensen, M.W.; Sorenson, C.

    1997-07-01

    The report discusses methods that can be used to estimate the emissions from various kinds of railway traffic. The methods are based on the estimation of the energy consumption of the train, so that comparisons can be made between electric and diesel driven trains. Typical values are given for the necessary traffic parameters, emission factors, and train loading. Detailed models for train energy consumption are presented, as well as empirically based methods using average train speed and distance between stop. (au)

  9. Efficient, Differentially Private Point Estimators

    OpenAIRE

    Smith, Adam

    2008-01-01

    Differential privacy is a recent notion of privacy for statistical databases that provides rigorous, meaningful confidentiality guarantees, even in the presence of an attacker with access to arbitrary side information. We show that for a large class of parametric probability models, one can construct a differentially private estimator whose distribution converges to that of the maximum likelihood estimator. In particular, it is efficient and asymptotically unbiased. This result provides (furt...

  10. Computer-Aided Parts Estimation

    OpenAIRE

    Cunningham, Adam; Smart, Robert

    1993-01-01

    In 1991, Ford Motor Company began deployment of CAPE (computer-aided parts estimating system), a highly advanced knowledge-based system designed to generate, evaluate, and cost automotive part manufacturing plans. cape is engineered on an innovative, extensible, declarative process-planning and estimating knowledge representation language, which underpins the cape kernel architecture. Many manufacturing processes have been modeled to date, but eventually every significant process in motor veh...

  11. Guideline to Estimate Decommissioning Costs

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Taesik; Kim, Younggook; Oh, Jaeyoung [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The primary objective of this work is to provide guidelines to estimate the decommissioning cost as well as the stakeholders with plausible information to understand the decommissioning activities in a reasonable manner, which eventually contribute to acquiring the public acceptance for the nuclear power industry. Although several cases of the decommissioning cost estimate have been made for a few commercial nuclear power plants, the different technical, site-specific and economic assumptions used make it difficult to interpret those cost estimates and compare them with that of a relevant plant. Trustworthy cost estimates are crucial to plan a safe and economic decommissioning project. The typical approach is to break down the decommissioning project into a series of discrete and measurable work activities. Although plant specific differences derived from the economic and technical assumptions make a licensee difficult to estimate reliable decommissioning costs, estimating decommissioning costs is the most crucial processes since it encompasses all the spectrum of activities from the planning to the final evaluation on whether a decommissioning project has successfully been preceded from the perspective of safety and economic points. Hence, it is clear that tenacious efforts should be needed to successfully perform the decommissioning project.

  12. Comparison of density estimators. [Estimation of probability density functions

    Energy Technology Data Exchange (ETDEWEB)

    Kao, S.; Monahan, J.F.

    1977-09-01

    Recent work in the field of probability density estimation has included the introduction of some new methods, such as the polynomial and spline methods and the nearest neighbor method, and the study of asymptotic properties in depth. This earlier work is summarized here. In addition, the computational complexity of the various algorithms is analyzed, as are some simulations. The object is to compare the performance of the various methods in small samples and their sensitivity to change in their parameters, and to attempt to discover at what point a sample is so small that density estimation can no longer be worthwhile. (RWR)

  13. Weldon Spring historical dose estimate

    International Nuclear Information System (INIS)

    Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

    1986-07-01

    This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr

  14. Weldon Spring historical dose estimate

    Energy Technology Data Exchange (ETDEWEB)

    Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

    1986-07-01

    This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr.

  15. An improved estimation and focusing scheme for vector velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Munk, Peter

    1999-01-01

    to reduce spatial velocity dispersion. Examples of different velocity vector conditions are shown using the Field II simulation program. A relative accuracy of 10.1 % is obtained for the lateral velocity estimates for a parabolic velocity profile for a flow perpendicular to the ultrasound beam and a signal...

  16. Robust Pitch Estimation Using an Optimal Filter on Frequency Estimates

    DEFF Research Database (Denmark)

    Karimian-Azari, Sam; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2014-01-01

    of such signals from unconstrained frequency estimates (UFEs). A minimum variance distortionless response (MVDR) method is proposed as an optimal solution to minimize the variance of UFEs considering the constraint of integer harmonics. The MVDR filter is designed based on noise statistics making it robust...

  17. estimating formwork striking time for concrete mixes estimating

    African Journals Online (AJOL)

    eobe

    In this study, we estimated the time for strength development in concrete cured up to 56 days. Water. In this .... regression analysis using MS Excel 2016 Software performed on the ..... [1] Abolfazl, K. R, Peroti S. and Rahemi L 'The Effect of.

  18. Moving Horizon Estimation and Control

    DEFF Research Database (Denmark)

    Jørgensen, John Bagterp

    successful and applied methodology beyond PID-control for control of industrial processes. The main contribution of this thesis is introduction and definition of the extended linear quadratic optimal control problem for solution of numerical problems arising in moving horizon estimation and control...... problems. Chapter 1 motivates moving horizon estimation and control as a paradigm for control of industrial processes. It introduces the extended linear quadratic control problem and discusses its central role in moving horizon estimation and control. Introduction, application and efficient solution....... It provides an algorithm for computation of the maximal output admissible set for linear model predictive control. Appendix D provides results concerning linear regression. Appendix E discuss prediction error methods for identification of linear models tailored for model predictive control....

  19. Heuristic introduction to estimation methods

    International Nuclear Information System (INIS)

    Feeley, J.J.; Griffith, J.M.

    1982-08-01

    The methods and concepts of optimal estimation and control have been very successfully applied in the aerospace industry during the past 20 years. Although similarities exist between the problems (control, modeling, measurements) in the aerospace and nuclear power industries, the methods and concepts have found only scant acceptance in the nuclear industry. Differences in technical language seem to be a major reason for the slow transfer of estimation and control methods to the nuclear industry. Therefore, this report was written to present certain important and useful concepts with a minimum of specialized language. By employing a simple example throughout the report, the importance of several information and uncertainty sources is stressed and optimal ways of using or allowing for these sources are presented. This report discusses optimal estimation problems. A future report will discuss optimal control problems

  20. Estimation of effective wind speed

    Science.gov (United States)

    Østergaard, K. Z.; Brath, P.; Stoustrup, J.

    2007-07-01

    The wind speed has a huge impact on the dynamic response of wind turbine. Because of this, many control algorithms use a measure of the wind speed to increase performance, e.g. by gain scheduling and feed forward. Unfortunately, no accurate measurement of the effective wind speed is online available from direct measurements, which means that it must be estimated in order to make such control methods applicable in practice. In this paper a new method is presented for the estimation of the effective wind speed. First, the rotor speed and aerodynamic torque are estimated by a combined state and input observer. These two variables combined with the measured pitch angle is then used to calculate the effective wind speed by an inversion of a static aerodynamic model.

  1. Estimation and valuation in accounting

    Directory of Open Access Journals (Sweden)

    Cicilia Ionescu

    2014-03-01

    Full Text Available The relationships of the enterprise with the external environment give rise to a range of informational needs. Satisfying those needs requires the production of coherent, comparable, relevant and reliable information included into the individual or consolidated financial statements. International Financial Reporting Standards IAS / IFRS aim to ensure the comparability and relevance of the accounting information, providing, among other things, details about the issue of accounting estimates and changes in accounting estimates. Valuation is a process continually used, in order to assign values to the elements that are to be recognised in the financial statements. Most of the times, the values reflected in the books are clear, they are recorded in the contracts with third parties, in the supporting documents, etc. However, the uncertainties in which a reporting entity operates determines that, sometimes, the assigned or values attributable to some items composing the financial statements be determined by use estimates.

  2. Integral Criticality Estimators in MCATK

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Los Alamos National Laboratory; Adams, Terry R. [Los Alamos National Laboratory; Sweezy, Jeremy Ed [Los Alamos National Laboratory

    2016-06-14

    The Monte Carlo Application ToolKit (MCATK) is a component-based software toolset for delivering customized particle transport solutions using the Monte Carlo method. Currently under development in the XCP Monte Carlo group at Los Alamos National Laboratory, the toolkit has the ability to estimate the ke f f and a eigenvalues for static geometries. This paper presents a description of the estimators and variance reduction techniques available in the toolkit and includes a preview of those slated for future releases. Along with the description of the underlying algorithms is a description of the available user inputs for controlling the iterations. The paper concludes with a comparison of the MCATK results with those provided by analytic solutions. The results match within expected statistical uncertainties and demonstrate MCATK’s usefulness in estimating these important quantities.

  3. Order statistics & inference estimation methods

    CERN Document Server

    Balakrishnan, N

    1991-01-01

    The literature on order statistics and inferenc eis quite extensive and covers a large number of fields ,but most of it is dispersed throughout numerous publications. This volume is the consolidtion of the most important results and places an emphasis on estimation. Both theoretical and computational procedures are presented to meet the needs of researchers, professionals, and students. The methods of estimation discussed are well-illustrated with numerous practical examples from both the physical and life sciences, including sociology,psychology,a nd electrical and chemical engineering. A co

  4. Methods for estimating the semivariogram

    DEFF Research Database (Denmark)

    Lophaven, Søren Nymand; Carstensen, Niels Jacob; Rootzen, Helle

    2002-01-01

    . In the existing literature various methods for modelling the semivariogram have been proposed, while only a few studies have been made on comparing different approaches. In this paper we compare eight approaches for modelling the semivariogram, i.e. six approaches based on least squares estimation...... maximum likelihood performed better than the least squares approaches. We also applied maximum likelihood and least squares estimation to a real dataset, containing measurements of salinity at 71 sampling stations in the Kattegat basin. This showed that the calculation of spatial predictions...

  5. Albedo estimation for scene segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C H; Rosenfeld, A

    1983-03-01

    Standard methods of image segmentation do not take into account the three-dimensional nature of the underlying scene. For example, histogram-based segmentation tacitly assumes that the image intensity is piecewise constant, and this is not true when the scene contains curved surfaces. This paper introduces a method of taking 3d information into account in the segmentation process. The image intensities are adjusted to compensate for the effects of estimated surface orientation; the adjusted intensities can be regarded as reflectivity estimates. When histogram-based segmentation is applied to these new values, the image is segmented into parts corresponding to surfaces of constant reflectivity in the scene. 7 references.

  6. Estimation of strong ground motion

    International Nuclear Information System (INIS)

    Watabe, Makoto

    1993-01-01

    Fault model has been developed to estimate a strong ground motion in consideration of characteristics of seismic source and propagation path of seismic waves. There are two different approaches in the model. The first one is a theoretical approach, while the second approach is a semi-empirical approach. Though the latter is more practical than the former to be applied to the estimation of input motions, it needs at least the small-event records, the value of the seismic moment of the small event and the fault model of the large event

  7. Fault sound sources position estimation based on L array method%基于L型阵列的故障声源位置估计

    Institute of Scientific and Technical Information of China (English)

    刘斌; 栾忠权; 马超; 余周祥

    2017-01-01

    The traditional method of fault diagnosis is mainly based on the analysis of the vibration, whichhas great limitations in some special circumstances, but the method based on the sound signal from the equipment in the process can solve the problem.A new method for fault diagnosis based on L type acoustic array is presented in this paper.The DOA estimation based on two-dimensional MUSIC is used in radar, and the performance of the algorithm is studied.And with three kinds of different parameterson 2DDOA estimation, the computation is carried out.The comparison with the result of the rectangular arraysis carried out.The resultsshowthat the corresponding algorithm performance is changed while the different parameters have different values.And the method with suitable parameters could be better for the fault diagnosis of the gear drive system.%传统的故障诊断方法主要是基于接触式的振动信号分析,在某些特殊环境下该方法具有很大的局限性,而基于设备运转过程中的声音信号就可以解决该问题.提出了基于L型声阵列的位置估计方法来进行故障诊断,采取了雷达中常用的基于二维MUSIC的DOA估计,并研究了算法的估计性能情况.分别研究了在不同的阵元个数、信噪比和快拍数下的2D-DOA估计的计算机仿真结果,并和基于矩形阵列的DOA估计进行了比较.研究结果表明,在不同的参数下该算法的估计结果也会有很大的不同.所以在选择合适的参数条件下,该算法可以应用于齿轮箱的故障诊断中.

  8. Multicollinearity and maximum entropy leuven estimator

    OpenAIRE

    Sudhanshu Mishra

    2004-01-01

    Multicollinearity is a serious problem in applied regression analysis. Q. Paris (2001) introduced the MEL estimator to resolve the multicollinearity problem. This paper improves the MEL estimator to the Modular MEL (MMEL) estimator and shows by Monte Carlo experiments that MMEL estimator performs significantly better than OLS as well as MEL estimators.

  9. Unrecorded Alcohol Consumption: Quantitative Methods of Estimation

    OpenAIRE

    Razvodovsky, Y. E.

    2010-01-01

    unrecorded alcohol; methods of estimation In this paper we focused on methods of estimation of unrecorded alcohol consumption level. Present methods of estimation of unrevorded alcohol consumption allow only approximate estimation of unrecorded alcohol consumption level. Tacking into consideration the extreme importance of such kind of data, further investigation is necessary to improve the reliability of methods estimation of unrecorded alcohol consumption.

  10. Collider Scaling and Cost Estimation

    International Nuclear Information System (INIS)

    Palmer, R.B.

    1986-01-01

    This paper deals with collider cost and scaling. The main points of the discussion are the following ones: 1) scaling laws and cost estimation: accelerating gradient requirements, total stored RF energy considerations, peak power consideration, average power consumption; 2) cost optimization; 3) Bremsstrahlung considerations; 4) Focusing optics: conventional, laser focusing or super disruption. 13 refs

  11. Helicopter Toy and Lift Estimation

    Science.gov (United States)

    Shakerin, Said

    2013-01-01

    A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

  12. Estimation of potential uranium resources

    International Nuclear Information System (INIS)

    Curry, D.L.

    1977-09-01

    Potential estimates, like reserves, are limited by the information on hand at the time and are not intended to indicate the ultimate resources. Potential estimates are based on geologic judgement, so their reliability is dependent on the quality and extent of geologic knowledge. Reliability differs for each of the three potential resource classes. It is greatest for probable potential resources because of the greater knowledge base resulting from the advanced stage of exploration and development in established producing districts where most of the resources in this class are located. Reliability is least for speculative potential resources because no significant deposits are known, and favorability is inferred from limited geologic data. Estimates of potential resources are revised as new geologic concepts are postulated, as new types of uranium ore bodies are discovered, and as improved geophysical and geochemical techniques are developed and applied. Advances in technology that permit the exploitation of deep or low-grade deposits, or the processing of ores of previously uneconomic metallurgical types, also will affect the estimates

  13. An Improved Cluster Richness Estimator

    Energy Technology Data Exchange (ETDEWEB)

    Rozo, Eduardo; /Ohio State U.; Rykoff, Eli S.; /UC, Santa Barbara; Koester, Benjamin P.; /Chicago U. /KICP, Chicago; McKay, Timothy; /Michigan U.; Hao, Jiangang; /Michigan U.; Evrard, August; /Michigan U.; Wechsler, Risa H.; /SLAC; Hansen, Sarah; /Chicago U. /KICP, Chicago; Sheldon, Erin; /New York U.; Johnston, David; /Houston U.; Becker, Matthew R.; /Chicago U. /KICP, Chicago; Annis, James T.; /Fermilab; Bleem, Lindsey; /Chicago U.; Scranton, Ryan; /Pittsburgh U.

    2009-08-03

    Minimizing the scatter between cluster mass and accessible observables is an important goal for cluster cosmology. In this work, we introduce a new matched filter richness estimator, and test its performance using the maxBCG cluster catalog. Our new estimator significantly reduces the variance in the L{sub X}-richness relation, from {sigma}{sub lnL{sub X}}{sup 2} = (0.86 {+-} 0.02){sup 2} to {sigma}{sub lnL{sub X}}{sup 2} = (0.69 {+-} 0.02){sup 2}. Relative to the maxBCG richness estimate, it also removes the strong redshift dependence of the richness scaling relations, and is significantly more robust to photometric and redshift errors. These improvements are largely due to our more sophisticated treatment of galaxy color data. We also demonstrate the scatter in the L{sub X}-richness relation depends on the aperture used to estimate cluster richness, and introduce a novel approach for optimizing said aperture which can be easily generalized to other mass tracers.

  14. Estimation of Bridge Reliability Distributions

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper it is shown how the so-called reliability distributions can be estimated using crude Monte Carlo simulation. The main purpose is to demonstrate the methodology. Therefor very exact data concerning reliability and deterioration are not needed. However, it is intended in the paper to ...

  15. Estimation of Motion Vector Fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1993-01-01

    This paper presents an approach to the estimation of 2-D motion vector fields from time varying image sequences. We use a piecewise smooth model based on coupled vector/binary Markov random fields. We find the maximum a posteriori solution by simulated annealing. The algorithm generate sample...... fields by means of stochastic relaxation implemented via the Gibbs sampler....

  16. Multispacecraft current estimates at swarm

    DEFF Research Database (Denmark)

    Dunlop, M. W.; Yang, Y.-Y.; Yang, J.-Y.

    2015-01-01

    During the first several months of the three-spacecraft Swarm mission all three spacecraft camerepeatedly into close alignment, providing an ideal opportunity for validating the proposed dual-spacecraftmethod for estimating current density from the Swarm magnetic field data. Two of the Swarm...

  17. Estimating Swedish biomass energy supply

    International Nuclear Information System (INIS)

    Johansson, J.; Lundqvist, U.

    1999-01-01

    Biomass is suggested to supply an increasing amount of energy in Sweden. There have been several studies estimating the potential supply of biomass energy, including that of the Swedish Energy Commission in 1995. The Energy Commission based its estimates of biomass supply on five other analyses which presented a wide variation in estimated future supply, in large part due to differing assumptions regarding important factors. In this paper, these studies are assessed, and the estimated potential biomass energy supplies are discusses regarding prices, technical progress and energy policy. The supply of logging residues depends on the demand for wood products and is limited by ecological, technological, and economic restrictions. The supply of stemwood from early thinning for energy and of straw from cereal and oil seed production is mainly dependent upon economic considerations. One major factor for the supply of willow and reed canary grass is the size of arable land projected to be not needed for food and fodder production. Future supply of biomass energy depends on energy prices and technical progress, both of which are driven by energy policy priorities. Biomass energy has to compete with other energy sources as well as with alternative uses of biomass such as forest products and food production. Technical progress may decrease the costs of biomass energy and thus increase the competitiveness. Economic instruments, including carbon taxes and subsidies, and allocation of research and development resources, are driven by energy policy goals and can change the competitiveness of biomass energy

  18. Estimates of wildland fire emissions

    Science.gov (United States)

    Yongqiang Liu; John J. Qu; Wanting Wang; Xianjun Hao

    2013-01-01

    Wildland fire missions can significantly affect regional and global air quality, radiation, climate, and the carbon cycle. A fundamental and yet challenging prerequisite to understanding the environmental effects is to accurately estimate fire emissions. This chapter describes and analyzes fire emission calculations. Various techniques (field measurements, empirical...

  19. State Estimation for Tensegrity Robots

    Science.gov (United States)

    Caluwaerts, Ken; Bruce, Jonathan; Friesen, Jeffrey M.; Sunspiral, Vytas

    2016-01-01

    Tensegrity robots are a class of compliant robots that have many desirable traits when designing mass efficient systems that must interact with uncertain environments. Various promising control approaches have been proposed for tensegrity systems in simulation. Unfortunately, state estimation methods for tensegrity robots have not yet been thoroughly studied. In this paper, we present the design and evaluation of a state estimator for tensegrity robots. This state estimator will enable existing and future control algorithms to transfer from simulation to hardware. Our approach is based on the unscented Kalman filter (UKF) and combines inertial measurements, ultra wideband time-of-flight ranging measurements, and actuator state information. We evaluate the effectiveness of our method on the SUPERball, a tensegrity based planetary exploration robotic prototype. In particular, we conduct tests for evaluating both the robot's success in estimating global position in relation to fixed ranging base stations during rolling maneuvers as well as local behavior due to small-amplitude deformations induced by cable actuation.

  20. Fuel Estimation Using Dynamic Response

    National Research Council Canada - National Science Library

    Hines, Michael S

    2007-01-01

    ...?s simulated satellite (SimSAT) to known control inputs. With an iterative process, the moment of inertia of SimSAT about the yaw axis was estimated by matching a model of SimSAT to the measured angular rates...