WorldWideScience

Sample records for waveform research methods

  1. Efficient data retrieval method for similar plasma waveforms in EAST

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying, E-mail: liuying-ipp@szu.edu.cn [SZU-CASIPP Joint Laboratory for Applied Plasma, Shenzhen University, Shenzhen 518060 (China); Huang, Jianjun; Zhou, Huasheng; Wang, Fan [SZU-CASIPP Joint Laboratory for Applied Plasma, Shenzhen University, Shenzhen 518060 (China); Wang, Feng [Institute of Plasma Physics Chinese Academy of Sciences, Hefei 230031 (China)

    2016-11-15

    Highlights: • The proposed method is carried out by means of bounding envelope and angle distance. • It allows retrieving for whole similar waveforms of any time length. • In addition, the proposed method is also possible to retrieve subsequences. - Abstract: Fusion research relies highly on data analysis due to its massive-sized database. In the present work, we propose an efficient method for searching and retrieving similar plasma waveforms in Experimental Advanced Superconducting Tokamak (EAST). Based on Piecewise Linear Aggregate Approximation (PLAA) for extracting feature values, the searching process is accomplished in two steps. The first one is coarse searching to narrow down the search space, which is carried out by means of bounding envelope. The second step is fine searching to retrieval similar waveforms, which is implemented by the angle distance. The proposed method is tested in EAST databases and turns out to have good performance in retrieving similar waveforms.

  2. Waveform relaxation methods for implicit differential equations

    NARCIS (Netherlands)

    P.J. van der Houwen; W.A. van der Veen

    1996-01-01

    textabstractWe apply a Runge-Kutta-based waveform relaxation method to initial-value problems for implicit differential equations. In the implementation of such methods, a sequence of nonlinear systems has to be solved iteratively in each step of the integration process. The size of these systems

  3. Photonic arbitrary waveform generator based on Taylor synthesis method

    DEFF Research Database (Denmark)

    Liao, Shasha; Ding, Yunhong; Dong, Jianji

    2016-01-01

    Arbitrary waveform generation has been widely used in optical communication, radar system and many other applications. We propose and experimentally demonstrate a silicon-on-insulator (SOI) on chip optical arbitrary waveform generator, which is based on Taylor synthesis method. In our scheme......, a Gaussian pulse is launched to some cascaded microrings to obtain first-, second- and third-order differentiations. By controlling amplitude and phase of the initial pulse and successive differentiations, we can realize an arbitrary waveform generator according to Taylor expansion. We obtain several typical...... waveforms such as square waveform, triangular waveform, flat-top waveform, sawtooth waveform, Gaussian waveform and so on. Unlike other schemes based on Fourier synthesis or frequency-to-time mapping, our scheme is based on Taylor synthesis method. Our scheme does not require any spectral disperser or large...

  4. Optimal overlapping of waveform relaxation method for linear differential equations

    International Nuclear Information System (INIS)

    Yamada, Susumu; Ozawa, Kazufumi

    2000-01-01

    Waveform relaxation (WR) method is extremely suitable for solving large systems of ordinary differential equations (ODEs) on parallel computers, but the convergence of the method is generally slow. In order to accelerate the convergence, the methods which decouple the system into many subsystems with overlaps some of the components between the adjacent subsystems have been proposed. The methods, in general, converge much faster than the ones without overlapping, but the computational cost per iteration becomes larger due to the increase of the dimension of each subsystem. In this research, the convergence of the WR method for solving constant coefficients linear ODEs is investigated and the strategy to determine the number of overlapped components which minimizes the cost of the parallel computations is proposed. Numerical experiments on an SR2201 parallel computer show that the estimated number of the overlapped components by the proposed strategy is reasonable. (author)

  5. Designing waveforms for temporal encoding using a frequency sampling method

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2007-01-01

    was compared to a linear frequency modulated signal with amplitude tapering, previously used in clinical studies for synthetic transmit aperture imaging. The latter had a relatively flat spectrum which implied that the waveform tried to excite all frequencies including ones with low amplification. The proposed......In this paper a method for designing waveforms for temporal encoding in medical ultrasound imaging is described. The method is based on least squares optimization and is used to design nonlinear frequency modulated signals for synthetic transmit aperture imaging. By using the proposed design method...... waveform, on the other hand, was designed so that only frequencies where the transducer had a large amplification were excited. Hereby, unnecessary heating of the transducer could be avoided and the signal-tonoise ratio could be increased. The experimental ultrasound scanner RASMUS was used to evaluate...

  6. Preliminary assessment of the waveform inversion method for interpretation of cross-well seismic data from the thermal production test, JAPEX/JNOC/GSC et al. Mallik 5L-38 gas hydrate production research well

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T. [Nagoya Univ., Nagoya (Japan). Research Center for Seismology and Volcanology; Shimizu, S. [Japan National Oil Co., Chiba (Japan); Asakawa, E. [JGI Inc., Tokyo (Japan); Kamei, R.; Matsuoka, T. [Kyoto Univ., Kyoto (Japan). Dept. of Civil and Earth Resources Engineering

    2005-07-01

    The JAPEX/JNOC/GSC et al. Mallik 3L-38 and 4L-38 test wells were subjected to repeated cross-well seismic surveys before and during the gas production test from the gas-hydrate-bearing layer at a depth of about 905 to 920 m. High-resolution velocity images in the gas-hydrate-bearing layer were obtained using the frequency-domain nonlinear waveform inversion method. An acoustic waveform inversion method was used along with the frequency-domain approach in order to detect the change in acoustic properties of the gas-hydrate-bearing layer resulting from gas production. The layered structures with small lateral heterogeneities were reconstructed by tomography analysis of preprocessed waveform data using a smaller number of source-receiver pairs. Preliminary results reveal high velocity and very high attenuation in the gas-hydrate-bearing layers. No obvious velocity decreases were noted. Information for further detailed processing was also gathered.

  7. Method and apparatus for resonant frequency waveform modulation

    Science.gov (United States)

    Taubman, Matthew S [Richland, WA

    2011-06-07

    A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.

  8. Full Waveform Inversion Using Oriented Time Migration Method

    KAUST Repository

    Zhang, Zhendong

    2016-04-12

    Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have an inaccurate update direction leading the inversion to converge into what we refer to as local minima of the objective function. In this thesis, I first look into the subject of full model wavenumber to analysis the root of local minima and suggest the possible ways to avoid this problem. And then I analysis the possibility of recovering the corresponding wavenumber components through the existing inversion and migration algorithms. Migration can be taken as a generalized inversion method which mainly retrieves the high wavenumber part of the model. Conventional impedance inversion method gives a mapping relationship between the migration image (high wavenumber) and model parameters (full wavenumber) and thus provides a possible cascade inversion strategy to retrieve the full wavenumber components from seismic data. In the proposed approach, consider a mild lateral variation in the model, I find an analytical Frechet derivation corresponding to the new objective function. In the proposed approach, the gradient is given by the oriented time-domain imaging method. This is independent of the background velocity. Specifically, I apply the oriented time-domain imaging (which depends on the reflection slope instead of a background velocity) on the data residual to obtain the geometrical features of the velocity perturbation. Assuming that density is constant, the conventional 1D impedance inversion method is also applicable for 2D or 3D velocity inversion within the process of FWI. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearized representations of the reflection response. To eliminate the cross-talk artifacts between different parameters, I

  9. Full Waveform Inversion Using Oriented Time Migration Method

    KAUST Repository

    Zhang, Zhendong

    2016-01-01

    Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have

  10. Development of a research-oriented system for collecting mechanical ventilator waveform data.

    Science.gov (United States)

    Rehm, Gregory B; Kuhn, Brooks T; Delplanque, Jean-Pierre; Guo, Edward C; Lieng, Monica K; Nguyen, Jimmy; Anderson, Nicholas R; Adams, Jason Y

    2017-10-28

    Lack of access to high-frequency, high-volume patient-derived data, such as mechanical ventilator waveform data, has limited the secondary use of these data for research, quality improvement, and decision support. Existing methods for collecting these data are obtrusive, require high levels of technical expertise, and are often cost-prohibitive, limiting their use and scalability for research applications. We describe here the development of an unobtrusive, open-source, scalable, and user-friendly architecture for collecting, transmitting, and storing mechanical ventilator waveform data that is generalizable to other patient care devices. The system implements a software framework that automates and enforces end-to-end data collection and transmission. A web-based data management application facilitates nontechnical end users' abilities to manage data acquisition devices, mitigates data loss and misattribution, and automates data storage. Using this integrated system, we have been able to collect ventilator waveform data from >450 patients as part of an ongoing clinical study. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. A Denoising Method for LiDAR Full-Waveform Data

    Directory of Open Access Journals (Sweden)

    Xudong Lai

    2015-01-01

    Full Text Available Decomposition of LiDAR full-waveform data can not only enhance the density and positioning accuracy of a point cloud, but also provide other useful parameters, such as pulse width, peak amplitude, and peak position which are important information for subsequent processing. Full-waveform data usually contain some random noises. Traditional filtering algorithms always cause distortion in the waveform. λ/μ filtering algorithm is based on Mean Shift method. It can smooth the signal iteratively and will not cause any distortion in the waveform. In this paper, an improved λ/μ filtering algorithm is proposed, and several experiments on both simulated waveform data and real waveform data are implemented to prove the effectiveness of the proposed algorithm.

  12. Micro-seismic imaging using a source function independent full waveform inversion method

    KAUST Repository

    Wang, Hanchen; Alkhalifah, Tariq Ali

    2018-01-01

    hand, the conventional micro-seismic source locating methods require, in many cases manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI

  13. A semi-automatic method for peak and valley detection in free-breathing respiratory waveforms

    International Nuclear Information System (INIS)

    Lu Wei; Nystrom, Michelle M.; Parikh, Parag J.; Fooshee, David R.; Hubenschmidt, James P.; Bradley, Jeffrey D.; Low, Daniel A.

    2006-01-01

    The existing commercial software often inadequately determines respiratory peaks for patients in respiration correlated computed tomography. A semi-automatic method was developed for peak and valley detection in free-breathing respiratory waveforms. First the waveform is separated into breath cycles by identifying intercepts of a moving average curve with the inspiration and expiration branches of the waveform. Peaks and valleys were then defined, respectively, as the maximum and minimum between pairs of alternating inspiration and expiration intercepts. Finally, automatic corrections and manual user interventions were employed. On average for each of the 20 patients, 99% of 307 peaks and valleys were automatically detected in 2.8 s. This method was robust for bellows waveforms with large variations

  14. A new method for measuring the wall charge waveforms of AC PDP

    International Nuclear Information System (INIS)

    Liang Zhihu; Liu Zujun; Liu Chunliang

    2004-01-01

    A new method is developed to measure the wall charge waveforms in coplanar alternating current plasma display panel (AC PDP). In the method, two groups of display electrodes are selected from a coplanar AC PDP and two capacitors are respectively connected with these two groups of display electrodes in series, and a measuring circuit and a reference circuit are thus constructed. With the help of special processing, discharge takes place in the cells included in the measuring circuit under a normal drive voltage but no discharge takes place in the cells included in the reference circuit under a normal drive voltage. The wall charge waveforms are obtained from the voltage difference between the two capacitors. Using the method, the wall charge waveforms are measured during resetting period, addressing period and sustaining period for the 304.8 mm (12-inch) test PDP panel. The result shows that the wall voltage is about 96 V during the sustaining period. (authors)

  15. Waveform control for magnetic testers using a quasi-Newton method

    International Nuclear Information System (INIS)

    Yamamoto, Ken-ichi; Hanba, Shigeru

    2008-01-01

    A nonlinear iterative learning algorithm is proposed to make a voltage waveform in the secondary coil sinusoidal in this paper. The algorithm employs a globally convergent Jacobian-free quasi-Newton type solver that has a BFGS-like structure. This method functions well, and it is demonstrated using typical soft magnetic materials

  16. Micro-seismic Imaging Using a Source Independent Waveform Inversion Method

    KAUST Repository

    Wang, Hanchen

    2016-01-01

    waveform inversion (FWI) is widely used. The FWI method updates the velocity model by minimizing the misfit between the observed data and the predicted data. Using FWI to locate and image microseismic events allows for an automatic process (free of picking

  17. Remote Blood Pressure Waveform Sensing Method and Apparatus

    National Research Council Canada - National Science Library

    Antonelli, Lynn T

    2008-01-01

    The invention as disclosed is a non-contact method and apparatus for continuously monitoring a physiological event in a human or animal, such as blood pressure, which involves utilizing a laser-based...

  18. Some advanced parametric methods for assessing waveform distortion in a smart grid with renewable generation

    Science.gov (United States)

    Alfieri, Luisa

    2015-12-01

    Power quality (PQ) disturbances are becoming an important issue in smart grids (SGs) due to the significant economic consequences that they can generate on sensible loads. However, SGs include several distributed energy resources (DERs) that can be interconnected to the grid with static converters, which lead to a reduction of the PQ levels. Among DERs, wind turbines and photovoltaic systems are expected to be used extensively due to the forecasted reduction in investment costs and other economic incentives. These systems can introduce significant time-varying voltage and current waveform distortions that require advanced spectral analysis methods to be used. This paper provides an application of advanced parametric methods for assessing waveform distortions in SGs with dispersed generation. In particular, the Standard International Electrotechnical Committee (IEC) method, some parametric methods (such as Prony and Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT)), and some hybrid methods are critically compared on the basis of their accuracy and the computational effort required.

  19. Full waveform inversion using oriented time-domain imaging method for vertical transverse isotropic media

    KAUST Repository

    Zhang, Zhendong

    2017-07-11

    Full waveform inversion for reection events is limited by its linearized update re-quirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate, the resulting gradient can have an inaccurate update direction leading the inversion to converge what we refer to as local minima of the objective function. In our approach, we consider mild lateral variation in the model, and thus, use a gradient given by the oriented time-domain imaging method. Specifically, we apply the oriented time-domain imaging on the data residual to obtain the geometrical features of the velocity perturbation. After updating the model in the time domain, we convert the perturbation from the time domain to depth using the average velocity. Considering density is constant, we can expand the conventional 1D impedance inversion method to 2D or 3D velocity inversion within the process of full waveform inversion. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearized representations of the reection response. To eliminate the cross-talk artifacts between different parameters, we utilize what we consider being an optimal parametrization for this step. To do so, we extend the prestack time-domain migration image in incident angle dimension to incorporate angular dependence needed by the multiparameter inversion. For simple models, this approach provides an efficient and stable way to do full waveform inversion or modified seismic inversion and makes the anisotropic inversion more practicable. The proposed method still needs kinematically accurate initial models since it only recovers the high-wavenumber part as conventional full waveform inversion method does. Results on synthetic data of isotropic and anisotropic cases illustrate the benefits and limitations of this method.

  20. Multi-Gaussian fitting for pulse waveform using Weighted Least Squares and multi-criteria decision making method.

    Science.gov (United States)

    Wang, Lu; Xu, Lisheng; Feng, Shuting; Meng, Max Q-H; Wang, Kuanquan

    2013-11-01

    Analysis of pulse waveform is a low cost, non-invasive method for obtaining vital information related to the conditions of the cardiovascular system. In recent years, different Pulse Decomposition Analysis (PDA) methods have been applied to disclose the pathological mechanisms of the pulse waveform. All these methods decompose single-period pulse waveform into a constant number (such as 3, 4 or 5) of individual waves. Furthermore, those methods do not pay much attention to the estimation error of the key points in the pulse waveform. The estimation of human vascular conditions depends on the key points' positions of pulse wave. In this paper, we propose a Multi-Gaussian (MG) model to fit real pulse waveforms using an adaptive number (4 or 5 in our study) of Gaussian waves. The unknown parameters in the MG model are estimated by the Weighted Least Squares (WLS) method and the optimized weight values corresponding to different sampling points are selected by using the Multi-Criteria Decision Making (MCDM) method. Performance of the MG model and the WLS method has been evaluated by fitting 150 real pulse waveforms of five different types. The resulting Normalized Root Mean Square Error (NRMSE) was less than 2.0% and the estimation accuracy for the key points was satisfactory, demonstrating that our proposed method is effective in compressing, synthesizing and analyzing pulse waveforms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    Science.gov (United States)

    Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

    2017-01-01

    A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

  2. Assessing the blood pressure waveform of the carotid artery using an ultrasound image processing method

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani, Effat; Mokhtari-Dizaji, Manijhe [Dept. of Medical Physics, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Fatouraee, Nasser [Dept. of Medical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Saben, Hazhir [Dept. Radiology, Imaging Center of Imam Khomaini Hospital, Tehran Medical Sciences University, Tehran (Iran, Islamic Republic of)

    2017-04-15

    The aim of this study was to introduce and implement a noninvasive method to derive the carotid artery pressure waveform directly by processing diagnostic sonograms of the carotid artery. Ultrasound image sequences of 20 healthy male subjects (age, 36±9 years) were recorded during three cardiac cycles. The internal diameter and blood velocity waveforms were extracted from consecutive sonograms over the cardiac cycles by using custom analysis programs written in MATLAB. Finally, the application of a mathematical equation resulted in time changes of the arterial pressure. The resulting pressures were calibrated using the mean and the diastolic pressure of the radial artery. A good correlation was found between the mean carotid blood pressure obtained from the ultrasound image processing and the mean radial blood pressure obtained using a standard digital sphygmomanometer (R=0.91). The mean absolute difference between the carotid calibrated pulse pressures and those measured clinically was -1.333±6.548 mm Hg. The results of this study suggest that consecutive sonograms of the carotid artery can be used for estimating a blood pressure waveform. We believe that our results promote a noninvasive technique for clinical applications that overcomes the reproducibility problems of common carotid artery tonometry with technical and anatomical causes.

  3. Assessing the blood pressure waveform of the carotid artery using an ultrasound image processing method

    International Nuclear Information System (INIS)

    Soleimani, Effat; Mokhtari-Dizaji, Manijhe; Fatouraee, Nasser; Saben, Hazhir

    2017-01-01

    The aim of this study was to introduce and implement a noninvasive method to derive the carotid artery pressure waveform directly by processing diagnostic sonograms of the carotid artery. Ultrasound image sequences of 20 healthy male subjects (age, 36±9 years) were recorded during three cardiac cycles. The internal diameter and blood velocity waveforms were extracted from consecutive sonograms over the cardiac cycles by using custom analysis programs written in MATLAB. Finally, the application of a mathematical equation resulted in time changes of the arterial pressure. The resulting pressures were calibrated using the mean and the diastolic pressure of the radial artery. A good correlation was found between the mean carotid blood pressure obtained from the ultrasound image processing and the mean radial blood pressure obtained using a standard digital sphygmomanometer (R=0.91). The mean absolute difference between the carotid calibrated pulse pressures and those measured clinically was -1.333±6.548 mm Hg. The results of this study suggest that consecutive sonograms of the carotid artery can be used for estimating a blood pressure waveform. We believe that our results promote a noninvasive technique for clinical applications that overcomes the reproducibility problems of common carotid artery tonometry with technical and anatomical causes

  4. Bayesian and Classical Machine Learning Methods: A Comparison for Tree Species Classification with LiDAR Waveform Signatures

    Directory of Open Access Journals (Sweden)

    Tan Zhou

    2017-12-01

    Full Text Available A plethora of information contained in full-waveform (FW Light Detection and Ranging (LiDAR data offers prospects for characterizing vegetation structures. This study aims to investigate the capacity of FW LiDAR data alone for tree species identification through the integration of waveform metrics with machine learning methods and Bayesian inference. Specifically, we first conducted automatic tree segmentation based on the waveform-based canopy height model (CHM using three approaches including TreeVaW, watershed algorithms and the combination of TreeVaW and watershed (TW algorithms. Subsequently, the Random forests (RF and Conditional inference forests (CF models were employed to identify important tree-level waveform metrics derived from three distinct sources, such as raw waveforms, composite waveforms, the waveform-based point cloud and the combined variables from these three sources. Further, we discriminated tree (gray pine, blue oak, interior live oak and shrub species through the RF, CF and Bayesian multinomial logistic regression (BMLR using important waveform metrics identified in this study. Results of the tree segmentation demonstrated that the TW algorithms outperformed other algorithms for delineating individual tree crowns. The CF model overcomes waveform metrics selection bias caused by the RF model which favors correlated metrics and enhances the accuracy of subsequent classification. We also found that composite waveforms are more informative than raw waveforms and waveform-based point cloud for characterizing tree species in our study area. Both classical machine learning methods (the RF and CF and the BMLR generated satisfactory average overall accuracy (74% for the RF, 77% for the CF and 81% for the BMLR and the BMLR slightly outperformed the other two methods. However, these three methods suffered from low individual classification accuracy for the blue oak which is prone to being misclassified as the interior live oak due

  5. Micro-seismic imaging using a source function independent full waveform inversion method

    Science.gov (United States)

    Wang, Hanchen; Alkhalifah, Tariq

    2018-03-01

    At the heart of micro-seismic event measurements is the task to estimate the location of the source micro-seismic events, as well as their ignition times. The accuracy of locating the sources is highly dependent on the velocity model. On the other hand, the conventional micro-seismic source locating methods require, in many cases manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI) to locate and image micro-seismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, full waveform inversion of micro-seismic events faces incredible nonlinearity due to the unknown source locations (space) and functions (time). We developed a source function independent full waveform inversion of micro-seismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with these observed and modeled to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for the source wavelet in Z axis is extracted to check the accuracy of the inverted source image and velocity model. Also, angle gathers is calculated to assess the quality of the long wavelength component of the velocity model. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity for synthetic examples used here, like those corresponding to the Marmousi model and the SEG/EAGE overthrust model.

  6. Micro-seismic imaging using a source function independent full waveform inversion method

    KAUST Repository

    Wang, Hanchen

    2018-03-26

    At the heart of micro-seismic event measurements is the task to estimate the location of the source micro-seismic events, as well as their ignition times. The accuracy of locating the sources is highly dependent on the velocity model. On the other hand, the conventional micro-seismic source locating methods require, in many cases manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI) to locate and image micro-seismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, full waveform inversion of micro-seismic events faces incredible nonlinearity due to the unknown source locations (space) and functions (time). We developed a source function independent full waveform inversion of micro-seismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with these observed and modeled to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for the source wavelet in Z axis is extracted to check the accuracy of the inverted source image and velocity model. Also, angle gathers is calculated to assess the quality of the long wavelength component of the velocity model. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity for synthetic examples used here, like those corresponding to the Marmousi model and the SEG/EAGE overthrust model.

  7. Waveform control method for mitigating harmonics of inverter systems with nonlinear load

    DEFF Research Database (Denmark)

    Wang, Haoran; Zhu, Guorong; Fu, Xiaobin

    2015-01-01

    instability in the DC power system, lower its efficiency, and shorten the lifetime of the DC source. This paper presents a general waveform control method that can mitigate the injection of the low-frequency ripple current by the single-phase DC/AC inverter into the DC source. It also discusses the inhibiting......DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create...

  8. A New Time Calibration Method for Switched-capacitor-array-based Waveform Samplers.

    Science.gov (United States)

    Kim, H; Chen, C-T; Eclov, N; Ronzhin, A; Murat, P; Ramberg, E; Los, S; Moses, W; Choong, W-S; Kao, C-M

    2014-12-11

    We have developed a new time calibration method for the DRS4 waveform sampler that enables us to precisely measure the non-uniform sampling interval inherent in the switched-capacitor cells of the DRS4. The method uses the proportionality between the differential amplitude and sampling interval of adjacent switched-capacitor cells responding to a sawtooth-shape pulse. In the experiment, a sawtooth-shape pulse with a 40 ns period generated by a Tektronix AWG7102 is fed to a DRS4 evaluation board for calibrating the sampling intervals of all 1024 cells individually. The electronic time resolution of the DRS4 evaluation board with the new time calibration is measured to be ~2.4 ps RMS by using two simultaneous Gaussian pulses with 2.35 ns full-width at half-maximum and applying a Gaussian fit. The time resolution dependencies on the time difference with the new time calibration are measured and compared to results obtained by another method. The new method could be applicable for other switched-capacitor-array technology-based waveform samplers for precise time calibration.

  9. Full-waveform detection of non-impulsive seismic events based on time-reversal methods

    Science.gov (United States)

    Solano, Ericka Alinne; Hjörleifsdóttir, Vala; Liu, Qinya

    2017-12-01

    We present a full-waveform detection method for non-impulsive seismic events, based on time-reversal principles. We use the strain Green's tensor as a matched filter, correlating it with continuous observed seismograms, to detect non-impulsive seismic events. We show that this is mathematically equivalent to an adjoint method for detecting earthquakes. We define the detection function, a scalar valued function, which depends on the stacked correlations for a group of stations. Event detections are given by the times at which the amplitude of the detection function exceeds a given value relative to the noise level. The method can make use of the whole seismic waveform or any combination of time-windows with different filters. It is expected to have an advantage compared to traditional detection methods for events that do not produce energetic and impulsive P waves, for example glacial events, landslides, volcanic events and transform-fault earthquakes for events which velocity structure along the path is relatively well known. Furthermore, the method has advantages over empirical Greens functions template matching methods, as it does not depend on records from previously detected events, and therefore is not limited to events occurring in similar regions and with similar focal mechanisms as these events. The method is not specific to any particular way of calculating the synthetic seismograms, and therefore complicated structural models can be used. This is particularly beneficial for intermediate size events that are registered on regional networks, for which the effect of lateral structure on the waveforms can be significant. To demonstrate the feasibility of the method, we apply it to two different areas located along the mid-oceanic ridge system west of Mexico where non-impulsive events have been reported. The first study area is between Clipperton and Siqueiros transform faults (9°N), during the time of two earthquake swarms, occurring in March 2012 and May

  10. Microseismic imaging using a source-independent full-waveform inversion method

    KAUST Repository

    Wang, Hanchen

    2016-09-06

    Using full waveform inversion (FWI) to locate microseismic and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, waveform inversion of microseismic events faces incredible nonlinearity due to the unknown source location (space) and function (time). We develop a source independent FWI of microseismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for source wavelet in z axis is extracted to check the accuracy of the inverted source image and velocity model. Also the angle gather is calculated to see if the velocity model is correct. By inverting for all the source image, source wavelet and the velocity model, the proposed method produces good estimates of the source location, ignition time and the background velocity for part of the SEG overthrust model.

  11. Microseismic imaging using a source-independent full-waveform inversion method

    KAUST Repository

    Wang, Hanchen

    2016-01-01

    Using full waveform inversion (FWI) to locate microseismic and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, waveform inversion of microseismic events faces incredible nonlinearity due to the unknown source location (space) and function (time). We develop a source independent FWI of microseismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for source wavelet in z axis is extracted to check the accuracy of the inverted source image and velocity model. Also the angle gather is calculated to see if the velocity model is correct. By inverting for all the source image, source wavelet and the velocity model, the proposed method produces good estimates of the source location, ignition time and the background velocity for part of the SEG overthrust model.

  12. Inferring global upper-mantle shear attenuation structure by waveform tomography using the spectral element method

    Science.gov (United States)

    Karaoǧlu, Haydar; Romanowicz, Barbara

    2018-06-01

    We present a global upper-mantle shear wave attenuation model that is built through a hybrid full-waveform inversion algorithm applied to long-period waveforms, using the spectral element method for wavefield computations. Our inversion strategy is based on an iterative approach that involves the inversion for successive updates in the attenuation parameter (δ Q^{-1}_μ) and elastic parameters (isotropic velocity VS, and radial anisotropy parameter ξ) through a Gauss-Newton-type optimization scheme that employs envelope- and waveform-type misfit functionals for the two steps, respectively. We also include source and receiver terms in the inversion steps for attenuation structure. We conducted a total of eight iterations (six for attenuation and two for elastic structure), and one inversion for updates to source parameters. The starting model included the elastic part of the relatively high-resolution 3-D whole mantle seismic velocity model, SEMUCB-WM1, which served to account for elastic focusing effects. The data set is a subset of the three-component surface waveform data set, filtered between 400 and 60 s, that contributed to the construction of the whole-mantle tomographic model SEMUCB-WM1. We applied strict selection criteria to this data set for the attenuation iteration steps, and investigated the effect of attenuation crustal structure on the retrieved mantle attenuation structure. While a constant 1-D Qμ model with a constant value of 165 throughout the upper mantle was used as starting model for attenuation inversion, we were able to recover, in depth extent and strength, the high-attenuation zone present in the depth range 80-200 km. The final 3-D model, SEMUCB-UMQ, shows strong correlation with tectonic features down to 200-250 km depth, with low attenuation beneath the cratons, stable parts of continents and regions of old oceanic crust, and high attenuation along mid-ocean ridges and backarcs. Below 250 km, we observe strong attenuation in the

  13. Full Seismic Waveform Tomography of the Japan region using Adjoint Methods

    Science.gov (United States)

    Steptoe, Hamish; Fichtner, Andreas; Rickers, Florian; Trampert, Jeannot

    2013-04-01

    We present a full-waveform tomographic model of the Japan region based on spectral-element wave propagation, adjoint techniques and seismic data from dense station networks. This model is intended to further our understanding of both the complex regional tectonics and the finite rupture processes of large earthquakes. The shallow Earth structure of the Japan region has been the subject of considerable tomographic investigation. The islands of Japan exist in an area of significant plate complexity: subduction related to the Pacific and Philippine Sea plates is responsible for the majority of seismicity and volcanism of Japan, whilst smaller micro-plates in the region, including the Okhotsk, and Okinawa and Amur, part of the larger North America and Eurasia plates respectively, contribute significant local intricacy. In response to the need to monitor and understand the motion of these plates and their associated faults, numerous seismograph networks have been established, including the 768 station high-sensitivity Hi-net network, 84 station broadband F-net and the strong-motion seismograph networks K-net and KiK-net in Japan. We also include the 55 station BATS network of Taiwan. We use this exceptional coverage to construct a high-resolution model of the Japan region from the full-waveform inversion of over 15,000 individual component seismograms from 53 events that occurred between 1997 and 2012. We model these data using spectral-element simulations of seismic wave propagation at a regional scale over an area from 120°-150°E and 20°-50°N to a depth of around 500 km. We quantify differences between observed and synthetic waveforms using time-frequency misfits allowing us to separate both phase and amplitude measurements whilst exploiting the complete waveform at periods of 15-60 seconds. Fréchet kernels for these misfits are calculated via the adjoint method and subsequently used in an iterative non-linear conjugate-gradient optimization. Finally, we employ

  14. An intelligent detection method for high-field asymmetric waveform ion mobility spectrometry.

    Science.gov (United States)

    Li, Yue; Yu, Jianwen; Ruan, Zhiming; Chen, Chilai; Chen, Ran; Wang, Han; Liu, Youjiang; Wang, Xiaozhi; Li, Shan

    2018-04-01

    In conventional high-field asymmetric waveform ion mobility spectrometry signal acquisition, multi-cycle detection is time consuming and limits somewhat the technique's scope for rapid field detection. In this study, a novel intelligent detection approach has been developed in which a threshold was set on the relative error of α parameters, which can eliminate unnecessary time spent on detection. In this method, two full-spectrum scans were made in advance to obtain the estimated compensation voltage at different dispersion voltages, resulting in a narrowing down of the whole scan area to just the peak area(s) of interest. This intelligent detection method can reduce the detection time to 5-10% of that of the original full-spectrum scan in a single cycle.

  15. Accurate Methods for Signal Processing of Distorted Waveforms in Power Systems

    Directory of Open Access Journals (Sweden)

    Langella R

    2007-01-01

    Full Text Available A primary problem in waveform distortion assessment in power systems is to examine ways to reduce the effects of spectral leakage. In the framework of DFT approaches, line frequency synchronization techniques or algorithms to compensate for desynchronization are necessary; alternative approaches such as those based on the Prony and ESPRIT methods are not sensitive to desynchronization, but they often require significant computational burden. In this paper, the signal processing aspects of the problem are considered; different proposals by the same authors regarding DFT-, Prony-, and ESPRIT-based advanced methods are reviewed and compared in terms of their accuracy and computational efforts. The results of several numerical experiments are reported and analysed; some of them are in accordance with IEC Standards, while others use more open scenarios.

  16. A New Waveform Signal Processing Method Based on Adaptive Clustering-Genetic Algorithms

    International Nuclear Information System (INIS)

    Noha Shaaban; Fukuzo Masuda; Hidetsugu Morota

    2006-01-01

    We present a fast digital signal processing method for numerical analysis of individual pulses from CdZnTe compound semiconductor detectors. Using Maxi-Mini Distance Algorithm and Genetic Algorithms based discrimination technique. A parametric approach has been used for classifying the discriminated waveforms into a set of clusters each has a similar signal shape with a corresponding pulse height spectrum. A corrected total pulse height spectrum was obtained by applying a normalization factor for the full energy peak for each cluster with a highly improvements in the energy spectrum characteristics. This method applied successfully for both simulated and real measured data, it can be applied to any detector suffers from signal shape variation. (authors)

  17. Full waveform seismic AVAZ signatures of anisotropic shales by integrated rock physics and the reflectivity method

    Science.gov (United States)

    Liu, Xiwu; Guo, Zhiqi; Han, Xu

    2018-06-01

    A set of parallel vertical fractures embedded in a vertically transverse isotropy (VTI) background leads to orthorhombic anisotropy and corresponding azimuthal seismic responses. We conducted seismic modeling of full waveform amplitude variations versus azimuth (AVAZ) responses of anisotropic shale by integrating a rock physics model and a reflectivity method. The results indicate that the azimuthal variation of P-wave velocity tends to be more complicated for orthorhombic medium compared to the horizontally transverse isotropy (HTI) case, especially at high polar angles. Correspondingly, for the HTI layer in the theoretical model, the short axis of the azimuthal PP amplitudes at the top interface is parallel to the fracture strike, while the long axis at the bottom reflection directs the fracture strike. In contrast, the orthorhombic layer in the theoretical model shows distinct AVAZ responses in terms of PP reflections. Nevertheless, the azimuthal signatures of the R- and T-components of the mode-converted PS reflections show similar AVAZ features for the HTI and orthorhombic layers, which may imply that the PS responses are dominated by fractures. For the application to real data, a seismic-well tie based on upscaled data and a reflectivity method illustrate good agreement between the reference layers and the corresponding reflected events. Finally, the full waveform seismic AVAZ responses of the Longmaxi shale formation are computed for the cases of HTI and orthorhombic anisotropy for comparison. For the two cases, the azimuthal features represent differences mainly in amplitudes, while slightly in the phases of the reflected waveforms. Azimuth variations in the PP reflections from the reference layers show distinct behaviors for the HTI and orthorhombic cases, while the mode-converted PS reflections in terms of the R- and T-components show little differences in azimuthal features. It may suggest that the behaviors of the PS waves are dominated by vertically

  18. An Overview of Radar Waveform Optimization for Target Detection

    Directory of Open Access Journals (Sweden)

    Wang Lulu

    2016-10-01

    Full Text Available An optimal waveform design method that fully employs the knowledge of the target and the environment can further improve target detection performance, thus is of vital importance to research. In this paper, methods of radar waveform optimization for target detection are reviewed and summarized and provide the basis for the research.

  19. Total variation regularization for seismic waveform inversion using an adaptive primal dual hybrid gradient method

    Science.gov (United States)

    Yong, Peng; Liao, Wenyuan; Huang, Jianping; Li, Zhenchuan

    2018-04-01

    Full waveform inversion is an effective tool for recovering the properties of the Earth from seismograms. However, it suffers from local minima caused mainly by the limited accuracy of the starting model and the lack of a low-frequency component in the seismic data. Because of the high velocity contrast between salt and sediment, the relation between the waveform and velocity perturbation is strongly nonlinear. Therefore, salt inversion can easily get trapped in the local minima. Since the velocity of salt is nearly constant, we can make the most of this characteristic with total variation regularization to mitigate the local minima. In this paper, we develop an adaptive primal dual hybrid gradient method to implement total variation regularization by projecting the solution onto a total variation norm constrained convex set, through which the total variation norm constraint is satisfied at every model iteration. The smooth background velocities are first inverted and the perturbations are gradually obtained by successively relaxing the total variation norm constraints. Numerical experiment of the projection of the BP model onto the intersection of the total variation norm and box constraints has demonstrated the accuracy and efficiency of our adaptive primal dual hybrid gradient method. A workflow is designed to recover complex salt structures in the BP 2004 model and the 2D SEG/EAGE salt model, starting from a linear gradient model without using low-frequency data below 3 Hz. The salt inversion processes demonstrate that wavefield reconstruction inversion with a total variation norm and box constraints is able to overcome local minima and inverts the complex salt velocity layer by layer.

  20. Micro-seismic Imaging Using a Source Independent Waveform Inversion Method

    KAUST Repository

    Wang, Hanchen

    2016-04-18

    Micro-seismology is attracting more and more attention in the exploration seismology community. The main goal in micro-seismic imaging is to find the source location and the ignition time in order to track the fracture expansion, which will help engineers monitor the reservoirs. Conventional imaging methods work fine in this field but there are many limitations such as manual picking, incorrect migration velocity and low signal to noise ratio (S/N). In traditional surface survey imaging, full waveform inversion (FWI) is widely used. The FWI method updates the velocity model by minimizing the misfit between the observed data and the predicted data. Using FWI to locate and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. Use the FWI technique, and overcomes the difficulties of manual pickings and incorrect velocity model for migration. However, the technique of waveform inversion of micro-seismic events faces its own problems. There is significant nonlinearity due to the unknown source location (space) and function (time). We have developed a source independent FWI of micro-seismic events to simultaneously invert for the source image, source function and velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. To examine the accuracy of the inverted source image and velocity model the extended image for source wavelet in z-axis is extracted. Also the angle gather is calculated to check the applicability of the migration velocity. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity in the synthetic experiments with both parts of the Marmousi and the SEG

  1. Full waveform inversion using oriented time-domain imaging method for vertical transverse isotropic media

    KAUST Repository

    Zhang, Zhendong; Alkhalifah, Tariq Ali

    2017-01-01

    Full waveform inversion for reection events is limited by its linearized update re-quirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate, the resulting gradient can have an inaccurate

  2. Optimized waveform relaxation domain decomposition method for discrete finite volume non stationary convection diffusion equation

    International Nuclear Information System (INIS)

    Berthe, P.M.

    2013-01-01

    In the context of nuclear waste repositories, we consider the numerical discretization of the non stationary convection diffusion equation. Discontinuous physical parameters and heterogeneous space and time scales lead us to use different space and time discretizations in different parts of the domain. In this work, we choose the discrete duality finite volume (DDFV) scheme and the discontinuous Galerkin scheme in time, coupled by an optimized Schwarz waveform relaxation (OSWR) domain decomposition method, because this allows the use of non-conforming space-time meshes. The main difficulty lies in finding an upwind discretization of the convective flux which remains local to a sub-domain and such that the multi domain scheme is equivalent to the mono domain one. These difficulties are first dealt with in the one-dimensional context, where different discretizations are studied. The chosen scheme introduces a hybrid unknown on the cell interfaces. The idea of up winding with respect to this hybrid unknown is extended to the DDFV scheme in the two-dimensional setting. The well-posedness of the scheme and of an equivalent multi domain scheme is shown. The latter is solved by an OSWR algorithm, the convergence of which is proved. The optimized parameters in the Robin transmission conditions are obtained by studying the continuous or discrete convergence rates. Several test-cases, one of which inspired by nuclear waste repositories, illustrate these results. (author) [fr

  3. A Joint Method of Envelope Inversion Combined with Hybrid-domain Full Waveform Inversion

    Science.gov (United States)

    CUI, C.; Hou, W.

    2017-12-01

    Full waveform inversion (FWI) aims to construct high-precision subsurface models by fully using the information in seismic records, including amplitude, travel time, phase and so on. However, high non-linearity and the absence of low frequency information in seismic data lead to the well-known cycle skipping problem and make inversion easily fall into local minima. In addition, those 3D inversion methods that are based on acoustic approximation ignore the elastic effects in real seismic field, and make inversion harder. As a result, the accuracy of final inversion results highly relies on the quality of initial model. In order to improve stability and quality of inversion results, multi-scale inversion that reconstructs subsurface model from low to high frequency are applied. But, the absence of very low frequencies (time domain and inversion in the frequency domain. To accelerate the inversion, we adopt CPU/GPU heterogeneous computing techniques. There were two levels of parallelism. In the first level, the inversion tasks are decomposed and assigned to each computation node by shot number. In the second level, GPU multithreaded programming is used for the computation tasks in each node, including forward modeling, envelope extraction, DFT (discrete Fourier transform) calculation and gradients calculation. Numerical tests demonstrated that the combined envelope inversion + hybrid-domain FWI could obtain much faithful and accurate result than conventional hybrid-domain FWI. The CPU/GPU heterogeneous parallel computation could improve the performance speed.

  4. Surrogate waveform models

    Science.gov (United States)

    Blackman, Jonathan; Field, Scott; Galley, Chad; Scheel, Mark; Szilagyi, Bela; Tiglio, Manuel

    2015-04-01

    With the advanced detector era just around the corner, there is a strong need for fast and accurate models of gravitational waveforms from compact binary coalescence. Fast surrogate models can be built out of an accurate but slow waveform model with minimal to no loss in accuracy, but may require a large number of evaluations of the underlying model. This may be prohibitively expensive if the underlying is extremely slow, for example if we wish to build a surrogate for numerical relativity. We examine alternate choices to building surrogate models which allow for a more sparse set of input waveforms. Research supported in part by NSERC.

  5. Revised method for forest canopy height estimation from Geoscience Laser Altimeter System waveforms.

    Science.gov (United States)

    Michael A. Lefskya; Michael Keller; Yong Panga; Plinio B. de Camargod; Maria O. Hunter

    2007-01-01

    The vertical extent of waveforms collected by the Geoscience Laser Altimeter System (onboard ICESat - the Ice, Cloud, and land Elevation Satellite) increases as a function of terrain slope and footprint size (the area on the ground that is illuminated by the laser). Over sloped terrain, returns from both canopy and ground surfaces can occur at the same elevation. As a...

  6. A New Wave Equation Based Source Location Method with Full-waveform Inversion

    KAUST Repository

    Wu, Zedong; Alkhalifah, Tariq Ali

    2017-01-01

    with illumination artifacts. We develop a waveform inversion approach with an additional penalty term in the objective function to reward the focusing of the source image. This penalty term is relaxed early to allow for data fitting, and avoid cycle skipping, using

  7. Multi-frequency accelerating strategy for the contrast source inversion method of ultrasound waveform tomography using pulse data

    Science.gov (United States)

    Lin, Hongxiang; Azuma, Takashi; Qu, Xiaolei; Takagi, Shu

    2017-03-01

    In this work, we construct a multi-frequency accelerating strategy for the contrast source inversion (CSI) method using pulse data in the time domain. CSI is a frequency-domain inversion method for ultrasound waveform tomography that does not require the forward solver through the process of reconstruction. Several prior researches show that the CSI method has a good performance of convergence and accuracy in the low-center-frequency situation. In contrast, utilizing the high-center-frequency data leads to a high-resolution reconstruction but slow convergence on large numbers of grid. Our objective is to take full advantage of all low frequency components from pulse data with the high-center-frequency data measured by the diagnostic device. First we process the raw data in the frequency domain. Then multi-frequency accelerating strategy helps restart CSI in the current frequency using the last iteration result obtained from the lower frequency component. The merit of multi- frequency accelerating strategy is that computational burden decreases at the first few iterations. Because the low frequency component of dataset computes on the coarse grid with assuming a fixed number of points per wavelength. In the numerical test, the pulse data were generated by the K-wave simulator and have been processed to meet the computation of the CSI method. We investigate the performance of the multi-frequency and single-frequency reconstructions and conclude that the multi-frequency accelerating strategy significantly enhances the quality of the reconstructed image and simultaneously reduces the average computational time for any iteration step.

  8. A Concealed Car Extraction Method Based on Full-Waveform LiDAR Data

    Directory of Open Access Journals (Sweden)

    Chuanrong Li

    2016-01-01

    Full Text Available Concealed cars extraction from point clouds data acquired by airborne laser scanning has gained its popularity in recent years. However, due to the occlusion effect, the number of laser points for concealed cars under trees is not enough. Thus, the concealed cars extraction is difficult and unreliable. In this paper, 3D point cloud segmentation and classification approach based on full-waveform LiDAR was presented. This approach first employed the autocorrelation G coefficient and the echo ratio to determine concealed cars areas. Then the points in the concealed cars areas were segmented with regard to elevation distribution of concealed cars. Based on the previous steps, a strategy integrating backscattered waveform features and the view histogram descriptor was developed to train sample data of concealed cars and generate the feature pattern. Finally concealed cars were classified by pattern matching. The approach was validated by full-waveform LiDAR data and experimental results demonstrated that the presented approach can extract concealed cars with accuracy more than 78.6% in the experiment areas.

  9. Elastic full waveform inversion based on the homogenization method: theoretical framework and 2-D numerical illustrations

    Science.gov (United States)

    Capdeville, Yann; Métivier, Ludovic

    2018-05-01

    Seismic imaging is an efficient tool to investigate the Earth interior. Many of the different imaging techniques currently used, including the so-called full waveform inversion (FWI), are based on limited frequency band data. Such data are not sensitive to the true earth model, but to a smooth version of it. This smooth version can be related to the true model by the homogenization technique. Homogenization for wave propagation in deterministic media with no scale separation, such as geological media, has been recently developed. With such an asymptotic theory, it is possible to compute an effective medium valid for a given frequency band such that effective waveforms and true waveforms are the same up to a controlled error. In this work we make the link between limited frequency band inversion, mainly FWI, and homogenization. We establish the relation between a true model and an FWI result model. This relation is important for a proper interpretation of FWI images. We numerically illustrate, in the 2-D case, that an FWI result is at best the homogenized version of the true model. Moreover, it appears that the homogenized FWI model is quite independent of the FWI parametrization, as long as it has enough degrees of freedom. In particular, inverting for the full elastic tensor is, in each of our tests, always a good choice. We show how the homogenization can help to understand FWI behaviour and help to improve its robustness and convergence by efficiently constraining the solution space of the inverse problem.

  10. Overview of intelligent data retrieval methods for waveforms and images in massive fusion databases

    Energy Technology Data Exchange (ETDEWEB)

    Vega, J. [JET-EFDA, Culham Science Center, OX14 3DB Abingdon (United Kingdom); Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: jesus.vega@ciemat.es; Murari, A. [JET-EFDA, Culham Science Center, OX14 3DB Abingdon (United Kingdom); Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padua (Italy); Pereira, A.; Portas, A.; Ratta, G.A.; Castro, R. [JET-EFDA, Culham Science Center, OX14 3DB Abingdon (United Kingdom); Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense 22, 28040 Madrid (Spain)

    2009-06-15

    JET database contains more than 42 Tbytes of data (waveforms and images) and it doubles its size about every 2 years. ITER database is expected to be orders of magnitude above this quantity. Therefore, data access in such huge databases can no longer be efficiently based on shot number or temporal interval. Taking into account that diagnostics generate reproducible signal patterns (structural shapes) for similar physical behaviour, high level data access systems can be developed. In these systems, the input parameter is a pattern and the outputs are the shot numbers and the temporal locations where similar patterns appear inside the database. These pattern oriented techniques can be used for first data screening of any type of morphological aspect of waveforms and images. The article shows a new technique to look for similar images in huge databases in a fast an efficient way. Also, previous techniques to search for similar waveforms and to retrieve time-series data or images containing any kind of patterns are reviewed.

  11. Binary black hole coalescence in the large-mass-ratio limit: The hyperboloidal layer method and waveforms at null infinity

    International Nuclear Information System (INIS)

    Bernuzzi, Sebastiano; Nagar, Alessandro; Zenginoglu, Anil

    2011-01-01

    We compute and analyze the gravitational waveform emitted to future null infinity by a system of two black holes in the large-mass-ratio limit. We consider the transition from the quasiadiabatic inspiral to plunge, merger, and ringdown. The relative dynamics is driven by a leading order in the mass ratio, 5PN-resummed, effective-one-body (EOB), analytic-radiation reaction. To compute the waveforms, we solve the Regge-Wheeler-Zerilli equations in the time-domain on a spacelike foliation, which coincides with the standard Schwarzschild foliation in the region including the motion of the small black hole, and is globally hyperboloidal, allowing us to include future null infinity in the computational domain by compactification. This method is called the hyperboloidal layer method, and is discussed here for the first time in a study of the gravitational radiation emitted by black hole binaries. We consider binaries characterized by five mass ratios, ν=10 -2,-3,-4,-5,-6 , that are primary targets of space-based or third-generation gravitational wave detectors. We show significative phase differences between finite-radius and null-infinity waveforms. We test, in our context, the reliability of the extrapolation procedure routinely applied to numerical relativity waveforms. We present an updated calculation of the final and maximum gravitational recoil imparted to the merger remnant by the gravitational wave emission, v kick end /(cν 2 )=0.04474±0.00007 and v kick max /(cν 2 )=0.05248±0.00008. As a self-consistency test of the method, we show an excellent fractional agreement (even during the plunge) between the 5PN EOB-resummed mechanical angular momentum loss and the gravitational wave angular momentum flux computed at null infinity. New results concerning the radiation emitted from unstable circular orbits are also presented. The high accuracy waveforms computed here could be considered for the construction of template banks or for calibrating analytic models such

  12. Mixed methods research.

    Science.gov (United States)

    Halcomb, Elizabeth; Hickman, Louise

    2015-04-08

    Mixed methods research involves the use of qualitative and quantitative data in a single research project. It represents an alternative methodological approach, combining qualitative and quantitative research approaches, which enables nurse researchers to explore complex phenomena in detail. This article provides a practical overview of mixed methods research and its application in nursing, to guide the novice researcher considering a mixed methods research project.

  13. Frequency sweep of the field scattered by an inhomogeneous structure using method of moments and asymptotic waveform evaluation

    DEFF Research Database (Denmark)

    Troelsen, Jens; Meincke, Peter; Breinbjerg, Olav

    2000-01-01

    into account. To the knowledge of the authors the AWE technique has not previously been applied to a MoM solution based on this kind of integral equation. It is the purpose of this paper to investigate the use of the AWE technique as a tool to obtain a fast frequency sweep of the field scattered......In many radar applications it is necessary to determine the scattering from an object over a wide frequency band. The asymptotic waveform evaluation (AWE), which is a moment matching (MM) technique, constitutes a method to this end. In general, MM techniques provide a reduced-order model...

  14. Waveform analysis of sound

    CERN Document Server

    Tohyama, Mikio

    2015-01-01

    What is this sound? What does that sound indicate? These are two questions frequently heard in daily conversation. Sound results from the vibrations of elastic media and in daily life provides informative signals of events happening in the surrounding environment. In interpreting auditory sensations, the human ear seems particularly good at extracting the signal signatures from sound waves. Although exploring auditory processing schemes may be beyond our capabilities, source signature analysis is a very attractive area in which signal-processing schemes can be developed using mathematical expressions. This book is inspired by such processing schemes and is oriented to signature analysis of waveforms. Most of the examples in the book are taken from data of sound and vibrations; however, the methods and theories are mostly formulated using mathematical expressions rather than by acoustical interpretation. This book might therefore be attractive and informative for scientists, engineers, researchers, and graduat...

  15. A New Wave Equation Based Source Location Method with Full-waveform Inversion

    KAUST Repository

    Wu, Zedong

    2017-05-26

    Locating the source of a passively recorded seismic event is still a challenging problem, especially when the velocity is unknown. Many imaging approaches to focus the image do not address the velocity issue and result in images plagued with illumination artifacts. We develop a waveform inversion approach with an additional penalty term in the objective function to reward the focusing of the source image. This penalty term is relaxed early to allow for data fitting, and avoid cycle skipping, using an extended source. At the later stages the focusing of the image dominates the inversion allowing for high resolution source and velocity inversion. We also compute the source location explicitly and numerical tests show that we obtain good estimates of the source locations with this approach.

  16. Research Note: Full-waveform inversion of the unwrapped phase of a model

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-12-06

    Reflections in seismic data induce serious non-linearity in the objective function of full- waveform inversion. Thus, without a good initial velocity model that can produce reflections within a half cycle of the frequency used in the inversion, convergence to a solution becomes difficult. As a result, we tend to invert for refracted events and damp reflections in data. Reflection induced non-linearity stems from cycle skipping between the imprint of the true model in observed data and the predicted model in synthesized data. Inverting for the phase of the model allows us to address this problem by avoiding the source of non-linearity, the phase wrapping phenomena. Most of the information related to the location (or depths) of interfaces is embedded in the phase component of a model, mainly influenced by the background model, while the velocity-contrast information (responsible for the reflection energy) is mainly embedded in the amplitude component. In combination with unwrapping the phase of data, which mitigates the non-linearity introduced by the source function, I develop a framework to invert for the unwrapped phase of a model, represented by the instantaneous depth, using the unwrapped phase of the data. The resulting gradient function provides a mechanism to non-linearly update the velocity model by applying mainly phase shifts to the model. In using the instantaneous depth as a model parameter, we keep track of the model properties unfazed by the wrapping phenomena. © 2013 European Association of Geoscientists & Engineers.

  17. Consumer Behavior Research Methods

    DEFF Research Database (Denmark)

    Chrysochou, Polymeros

    2017-01-01

    This chapter starts by distinguishing consumer behavior research methods based on the type of data used, being either secondary or primary. Most consumer behavior research studies phenomena that require researchers to enter the field and collect data on their own, and therefore the chapter...... emphasizes the discussion of primary research methods. Based on the nature of the data primary research methods are further distinguished into qualitative and quantitative. The chapter describes the most important and popular qualitative and quantitative methods. It concludes with an overall evaluation...... of the methods and how to improve quality in consumer behavior research methods....

  18. The optimized gradient method for full waveform inversion and its spectral implementation

    KAUST Repository

    Wu, Zedong; Alkhalifah, Tariq Ali

    2016-01-01

    At the heart of the full waveform inversion (FWI) implementation is wavefield extrapolation, and specifically its accuracy and cost. To obtain accurate, dispersion free wavefields, the extrapolation for modelling is often expensive. Combining an efficient extrapolation with a novel gradient preconditioning can render an FWI implementation that efficiently converges to an accurate model. We, specifically, recast the extrapolation part of the inversion in terms of its spectral components for both data and gradient calculation. This admits dispersion free wavefields even at large extrapolation time steps, which improves the efficiency of the inversion. An alternative spectral representation of the depth axis in terms of sine functions allows us to impose a free surface boundary condition, which reflects our medium boundaries more accurately. Using a newly derived perfectly matched layer formulation for this spectral implementation, we can define a finite model with absorbing boundaries. In order to reduce the nonlinearity in FWI, we propose a multiscale conditioning of the objective function through combining the different directional components of the gradient to optimally update the velocity. Through solving a simple optimization problem, it specifically admits the smoothest approximate update while guaranteeing its ascending direction. An application to the Marmousi model demonstrates the capability of the proposed approach and justifies our assertions with respect to cost and convergence.

  19. The optimized gradient method for full waveform inversion and its spectral implementation

    KAUST Repository

    Wu, Zedong

    2016-03-28

    At the heart of the full waveform inversion (FWI) implementation is wavefield extrapolation, and specifically its accuracy and cost. To obtain accurate, dispersion free wavefields, the extrapolation for modelling is often expensive. Combining an efficient extrapolation with a novel gradient preconditioning can render an FWI implementation that efficiently converges to an accurate model. We, specifically, recast the extrapolation part of the inversion in terms of its spectral components for both data and gradient calculation. This admits dispersion free wavefields even at large extrapolation time steps, which improves the efficiency of the inversion. An alternative spectral representation of the depth axis in terms of sine functions allows us to impose a free surface boundary condition, which reflects our medium boundaries more accurately. Using a newly derived perfectly matched layer formulation for this spectral implementation, we can define a finite model with absorbing boundaries. In order to reduce the nonlinearity in FWI, we propose a multiscale conditioning of the objective function through combining the different directional components of the gradient to optimally update the velocity. Through solving a simple optimization problem, it specifically admits the smoothest approximate update while guaranteeing its ascending direction. An application to the Marmousi model demonstrates the capability of the proposed approach and justifies our assertions with respect to cost and convergence.

  20. How far away is far enough for extracting numerical waveforms, and how much do they depend on the extraction method?

    Energy Technology Data Exchange (ETDEWEB)

    Pazos, Enrique [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Dorband, Ernst Nils [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Nagar, Alessandro [Dipartimento di Fisica, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino (Italy); Palenzuela, Carlos [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Schnetter, Erik [Center for Computation and Technology, 216 Johnston Hall, Louisiana State University, Baton Rouge, LA 70803 (United States); Tiglio, Manuel [Department of Physics and Astronomy, 202 Nicholson Hall, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2007-06-21

    We present a method for extracting gravitational waves from numerical spacetimes which generalizes and refines one of the standard methods based on the Regge-Wheeler-Zerilli perturbation formalism. At the analytical level, this generalization allows a much more general class of slicing conditions for the background geometry, and is thus not restricted to Schwarzschild-like coordinates. At the numerical level, our approach uses high-order multi-block methods, which improve both the accuracy of our simulations and of our extraction procedure. In particular, the latter is simplified since there is no need for interpolation, and we can afford to extract accurate waves at large radii with only little additional computational effort. We then present fully nonlinear three-dimensional numerical evolutions of a distorted Schwarzschild black hole in Kerr-Schild coordinates with an odd parity perturbation and analyse the improvement that we gain from our generalized wave extraction, comparing our new method to the standard one. In particular, we analyse in detail the quasinormal frequencies of the extracted waves, using both methods. We do so by comparing the extracted waves with one-dimensional high resolution solutions of the corresponding generalized Regge-Wheeler equation. We explicitly see that the errors in the waveforms extracted with the standard method at fixed, finite extraction radii do not converge to zero with increasing resolution. We find that even with observers as far out as R = 80M-which is larger than what is commonly used in state-of-the-art simulations-the assumption in the standard method that the background is close to having Schwarzschild-like coordinates increases the error in the extracted waves considerably. Furthermore, those errors are dominated by the extraction method itself and not by the accuracy of our simulations. For extraction radii between 20M and 80M and for the resolutions that we use in this paper, our new method decreases the errors

  1. How far away is far enough for extracting numerical waveforms, and how much do they depend on the extraction method?

    International Nuclear Information System (INIS)

    Pazos, Enrique; Dorband, Ernst Nils; Nagar, Alessandro; Palenzuela, Carlos; Schnetter, Erik; Tiglio, Manuel

    2007-01-01

    We present a method for extracting gravitational waves from numerical spacetimes which generalizes and refines one of the standard methods based on the Regge-Wheeler-Zerilli perturbation formalism. At the analytical level, this generalization allows a much more general class of slicing conditions for the background geometry, and is thus not restricted to Schwarzschild-like coordinates. At the numerical level, our approach uses high-order multi-block methods, which improve both the accuracy of our simulations and of our extraction procedure. In particular, the latter is simplified since there is no need for interpolation, and we can afford to extract accurate waves at large radii with only little additional computational effort. We then present fully nonlinear three-dimensional numerical evolutions of a distorted Schwarzschild black hole in Kerr-Schild coordinates with an odd parity perturbation and analyse the improvement that we gain from our generalized wave extraction, comparing our new method to the standard one. In particular, we analyse in detail the quasinormal frequencies of the extracted waves, using both methods. We do so by comparing the extracted waves with one-dimensional high resolution solutions of the corresponding generalized Regge-Wheeler equation. We explicitly see that the errors in the waveforms extracted with the standard method at fixed, finite extraction radii do not converge to zero with increasing resolution. We find that even with observers as far out as R = 80M-which is larger than what is commonly used in state-of-the-art simulations-the assumption in the standard method that the background is close to having Schwarzschild-like coordinates increases the error in the extracted waves considerably. Furthermore, those errors are dominated by the extraction method itself and not by the accuracy of our simulations. For extraction radii between 20M and 80M and for the resolutions that we use in this paper, our new method decreases the errors

  2. Research Methods in Education

    Science.gov (United States)

    Check, Joseph; Schutt, Russell K.

    2011-01-01

    "Research Methods in Education" introduces research methods as an integrated set of techniques for investigating questions about the educational world. This lively, innovative text helps students connect technique and substance, appreciate the value of both qualitative and quantitative methodologies, and make ethical research decisions.…

  3. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Jardak, Seifallah

    2014-09-01

    Correlated waveforms have a number of applications in different fields, such as radar and communication. It is very easy to generate correlated waveforms using infinite alphabets, but for some of the applications, it is very challenging to use them in practice. Moreover, to generate infinite alphabet constant envelope correlated waveforms, the available research uses iterative algorithms, which are computationally very expensive. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method map the Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability-density-function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. To generate equiprobable symbols, the area of each region is kept same. If the requirement is to have each symbol with its own unique probability, the proposed scheme allows us that as well. Although, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.

  4. Discontinuous Galerkin method for computing gravitational waveforms from extreme mass ratio binaries

    International Nuclear Information System (INIS)

    Field, Scott E; Hesthaven, Jan S; Lau, Stephen R

    2009-01-01

    Gravitational wave emission from extreme mass ratio binaries (EMRBs) should be detectable by the joint NASA-ESA LISA project, spurring interest in analytical and numerical methods for investigating EMRBs. We describe a discontinuous Galerkin (dG) method for solving the distributionally forced 1+1 wave equations which arise when modeling EMRBs via the perturbation theory of Schwarzschild black holes. Despite the presence of jump discontinuities in the relevant polar and axial gravitational 'master functions', our dG method achieves global spectral accuracy, provided that we know the instantaneous position, velocity and acceleration of the small particle. Here these variables are known, since we assume that the particle follows a timelike geodesic of the Schwarzschild geometry. We document the results of several numerical experiments testing our method, and in our concluding section discuss the possible inclusion of gravitational self-force effects.

  5. Harmonic arbitrary waveform generator

    Science.gov (United States)

    Roberts, Brock Franklin

    2017-11-28

    High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.

  6. Research on teaching methods.

    Science.gov (United States)

    Oermann, M H

    1990-01-01

    Research on teaching methods in nursing education was categorized into studies on media, CAI, and other nontraditional instructional strategies. While the research differed, some generalizations may be made from the findings. Multimedia, whether it is used for individual or group instruction, is at least as effective as traditional instruction (lecture and lecture-discussion) in promoting cognitive learning, retention of knowledge, and performance. Further study is needed to identify variables that may influence learning and retention. While learner attitudes toward mediated instruction tended to be positive, investigators failed to control for the effect of novelty. Control over intervening variables was lacking in the majority of studies as well. Research indicated that CAI is as effective as other teaching methods in terms of knowledge gain and retention. Attitudes toward CAI tended to be favorable, with similar problems in measurement as those evidenced in studies of media. Chang (1986) also recommends that future research examine the impact of computer-video interactive instruction on students, faculty, and settings. Research is needed on experimental teaching methods, strategies for teaching problem solving and clinical judgment, and ways of improving the traditional lecture and discussion. Limited research in these areas makes generalizations impossible. There is a particular need for research on how to teach students the diagnostic reasoning process and encourage critical thinking, both in terms of appropriate teaching methods and the way in which those strategies should be used. It is interesting that few researchers studied lecture and lecture-discussion except as comparable teaching methods for research on other strategies. Additional research questions may be generated on lecture and discussion in relation to promoting concept learning, an understanding of nursing and other theories, transfer of knowledge, and development of cognitive skills. Few

  7. The Linearized Bregman Method for Frugal Full-waveform Inversion with Compressive Sensing and Sparsity-promoting

    Science.gov (United States)

    Chai, Xintao; Tang, Genyang; Peng, Ronghua; Liu, Shaoyong

    2018-03-01

    Full-waveform inversion (FWI) reconstructs the subsurface properties from acquired seismic data via minimization of the misfit between observed and simulated data. However, FWI suffers from considerable computational costs resulting from the numerical solution of the wave equation for each source at each iteration. To reduce the computational burden, constructing supershots by combining several sources (aka source encoding) allows mitigation of the number of simulations at each iteration, but it gives rise to crosstalk artifacts because of interference between the individual sources of the supershot. A modified Gauss-Newton FWI (MGNFWI) approach showed that as long as the difference between the initial and true models permits a sparse representation, the ℓ _1-norm constrained model updates suppress subsampling-related artifacts. However, the spectral-projected gradient ℓ _1 (SPGℓ _1) algorithm employed by MGNFWI is rather complicated that makes its implementation difficult. To facilitate realistic applications, we adapt a linearized Bregman (LB) method to sparsity-promoting FWI (SPFWI) because of the efficiency and simplicity of LB in the framework of ℓ _1-norm constrained optimization problem and compressive sensing. Numerical experiments performed with the BP Salt model, the Marmousi model and the BG Compass model verify the following points. The FWI result with LB solving ℓ _1-norm sparsity-promoting problem for the model update outperforms that generated by solving ℓ _2-norm problem in terms of crosstalk elimination and high-fidelity results. The simpler LB method performs comparably and even superiorly to the complicated SPGℓ _1 method in terms of computational efficiency and model quality, making the LB method a viable alternative for realistic implementations of SPFWI.

  8. New Methods for the Detection and Interception of Frequency-Hopped Waveforms

    Science.gov (United States)

    1990-11-01

    that £[p2 Q2 /O] = uF + 2 + o(cos 0 + 6 sin9)2 + 4n(acos0+/3sin)(7ycos0+6sinO)+o r(acos0+sinO)2 I + ( acosO +/3sinO) 2(Tcos9+ 6sin O)2 (3.134) i which...Jcins I lopk ins lI mvtrsi! t3 A pplied Physics Laborator Before1 NII After Figure 4.4: Deconvolut ion Applivod to Oi-fFci i r 100 The Johns 11opkins...Arlington, VA 20360 Library 2 Naval Postgraduate School Monterey, CA 92940 Library 2 Naval Research Laborator . Washington, DC 20375 Library 2 J. W

  9. Optimization of the ship type using waveform by means of Rankine source method; Rankine source ho ni yoru hakei wo mochiita funagata saitekika ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Hirayama, A; Eguchi, T [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

    1996-04-10

    Among the numerical calculation methods for steady-state wave-making problems, the panel shift Rankine source (PSRS) method has the advantages of rather precise determination of wave pattern of practical ship types, and short calculation period. The wave pattern around the hull was calculated by means of the PSRS method. The waveform analysis was carried out for the wave, to obtain an amplitude function of the original ship type. Based on the amplitude function, a ship type improvement method aiming at the optimization of ship type was provided using a conditional calculus of variation. A Series 60 (Cb=0.6) ship type was selected for the ship type improvement, to apply this technique. It was suggested that optimum design can be made for reducing the wave making resistance by means of this method. For the improvement of Series 60 ship type using this method, a great degree of reduction in the wave making resistance was recognized from the results of numerical waveform analysis. It was suggested that the ship type improvement aiming at the reduction of wave-making resistance can be made in shorter period and by smaller labor compared with the method using a waveform analysis of cistern tests. 5 refs., 9 figs.

  10. Research methods in information

    CERN Document Server

    Pickard, Alison Jane

    2013-01-01

    The long-awaited 2nd edition of this best-selling research methods handbook is fully updated and includes brand new coverage of online research methods and techniques, mixed methodology and qualitative analysis. There is an entire chapter contributed by Professor Julie McLeod, Sue Childs and Elizabeth Lomas focusing on research data management, applying evidence from the recent JISC funded 'DATUM' project. The first to focus entirely on the needs of the information and communications community, it guides the would-be researcher through the variety of possibilities open to them under the heading "research" and provides students with the confidence to embark on their dissertations. The focus here is on the 'doing' and although the philosophy and theory of research is explored to provide context, this is essentially a practical exploration of the whole research process with each chapter fully supported by examples and exercises tried and tested over a whole teaching career. The book will take readers through eac...

  11. Ergonomics research methods

    Science.gov (United States)

    Uspenskiy, S. I.; Yermakova, S. V.; Chaynova, L. D.; Mitkin, A. A.; Gushcheva, T. M.; Strelkov, Y. K.; Tsvetkova, N. F.

    1973-01-01

    Various factors used in ergonomic research are given. They are: (1) anthrometric measurement, (2) polyeffector method of assessing the functional state of man, (3) galvanic skin reaction, (4) pneumography, (5) electromyography, (6) electrooculography, and (7) tachestoscopy. A brief summary is given of each factor and includes instrumentation and results.

  12. Programmable waveform controller

    International Nuclear Information System (INIS)

    Yeh, H.T.

    1979-01-01

    A programmable waveform controller (PWC) was developed for voltage waveform generation in the laboratory. It is based on the Intel 8080 family of chips. The hardware uses the modular board approach, sharing a common 44-pin bus. The software contains two separate programs: the first generates a single connected linear ramp waveform and is capable of bipolar operation, linear interpolation between input data points, extended time range, and cycling; the second generates four independent square waveforms with variable duration and amplitude

  13. Shallow crustal discontinuities inferred from waveforms of microearthquakes: Method and application to KTB Drill Site and West Bohemia Swarm Area

    Czech Academy of Sciences Publication Activity Database

    Hrubcová, Pavla; Vavryčuk, Václav; Boušková, Alena; Bohnhoff, M.

    2016-01-01

    Roč. 121, č. 2 (2016), s. 881-902 ISSN 2169-9313 R&D Projects: GA ČR GA13-08971S; GA MŠk LM2010008; GA ČR(CZ) GAP210/12/1491; GA ČR(CZ) GC16-19751J Institutional support: RVO:67985530 Keywords : crustal structure * waveform stacking * microearthquakes Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 3.350, year: 2016

  14. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    DEFF Research Database (Denmark)

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method, a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous-reference-frame-based methods. The analytical, simulation, and experimental studies of a 2.5 k...

  15. Waveform inversion for acoustic VTI media in frequency domain

    KAUST Repository

    Wu, Zedong; Alkhalifah, Tariq Ali

    2016-01-01

    Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the background model using a single scattered wavefield from an inverted perturbation. However, current

  16. Research Methods Tutorial

    Science.gov (United States)

    Aguilera, Frank J.

    2015-01-01

    A guiding principle for conducting research in technology, science, and engineering, leading to innovation is based on our use of research methodology (both qualitative and qualitative). A brief review of research methodology will be presented with an overview of NASA process in developing aeronautics technologies and other things to consider in research including what is innovation.

  17. Mixed methods research in music therapy research.

    Science.gov (United States)

    Bradt, Joke; Burns, Debra S; Creswell, John W

    2013-01-01

    Music therapists have an ethical and professional responsibility to provide the highest quality care possible to their patients. Much of the time, high quality care is guided by evidence-based practice standards that integrate the most current, available research in making decisions. Accordingly, music therapists need research that integrates multiple ways of knowing and forms of evidence. Mixed methods research holds great promise for facilitating such integration. At this time, there have not been any methodological articles published on mixed methods research in music therapy. The purpose of this article is to introduce mixed methods research as an approach to address research questions relevant to music therapy practice. This article describes the core characteristics of mixed methods research, considers paradigmatic issues related to this research approach, articulates major challenges in conducting mixed methods research, illustrates four basic designs, and provides criteria for evaluating the quality of mixed methods articles using examples of mixed methods research from the music therapy literature. Mixed methods research offers unique opportunities for strengthening the evidence base in music therapy. Recommendations are provided to ensure rigorous implementation of this research approach.

  18. Mixed methods research for TESOL

    CERN Document Server

    Brown, James; Farr, Fiona

    2014-01-01

    Defining and discussing the relevance of theoretical and practical issues involved in mixed methods research. Covering the basics of research methodology, this textbook shows you how to choose and combine quantitative and qualitative research methods to b

  19. Mixed methods for telehealth research.

    Science.gov (United States)

    Caffery, Liam J; Martin-Khan, Melinda; Wade, Victoria

    2017-10-01

    Mixed methods research is important to health services research because the integrated qualitative and quantitative investigation can give a more comprehensive understanding of complex interventions such as telehealth than can a single-method study. Further, mixed methods research is applicable to translational research and program evaluation. Study designs relevant to telehealth research are described and supported by examples. Quality assessment tools, frameworks to assist in the reporting and review of mixed methods research, and related methodologies are also discussed.

  20. Imaging disturbance zones ahead of a tunnel by elastic full-waveform inversion: Adjoint gradient based inversion vs. parameter space reduction using a level-set method

    Directory of Open Access Journals (Sweden)

    Andre Lamert

    2018-03-01

    Full Text Available We present and compare two flexible and effective methodologies to predict disturbance zones ahead of underground tunnels by using elastic full-waveform inversion. One methodology uses a linearized, iterative approach based on misfit gradients computed with the adjoint method while the other uses iterative, gradient-free unscented Kalman filtering in conjunction with a level-set representation. Whereas the former does not involve a priori assumptions on the distribution of elastic properties ahead of the tunnel, the latter introduces a massive reduction in the number of explicit model parameters to be inverted for by focusing on the geometric form of potential disturbances and their average elastic properties. Both imaging methodologies are validated through successful reconstructions of simple disturbances. As an application, we consider an elastic multiple disturbance scenario. By using identical synthetic time-domain seismograms as test data, we obtain satisfactory, albeit different, reconstruction results from the two inversion methodologies. The computational costs of both approaches are of the same order of magnitude, with the gradient-based approach showing a slight advantage. The model parameter space reduction approach compensates for this by additionally providing a posteriori estimates of model parameter uncertainty. Keywords: Tunnel seismics, Full waveform inversion, Seismic waves, Level-set method, Adjoint method, Kalman filter

  1. Transformative Mixed Methods Research

    Science.gov (United States)

    Mertens, Donna M.

    2010-01-01

    Paradigms serve as metaphysical frameworks that guide researchers in the identification and clarification of their beliefs with regard to ethics, reality, knowledge, and methodology. The transformative paradigm is explained and illustrated as a framework for researchers who place a priority on social justice and the furtherance of human rights.…

  2. Velocity structure around the 410 km discontinuity beneath the East China Sea based on the waveform modeling method

    Science.gov (United States)

    Li, W.; Cui, Q.; Gao, Y.; Wei, R.; Zhou, Y.; Yu, J.

    2017-12-01

    The 410 km discontinuity is the upper boundary of the mantle transition zone. Seismic detections on the structure and morphology of the 410 km discontinuity are helpful to understand the compositions of the Earth's interior and the relevant geodynamics. In this paper, we select the broadband P waveforms of an intermediate earthquake that occurred in the Ryukyu subduction zone and retrieved from the China Digital Seismograph Network, and study the fine velocity structure around the 410 km discontinuity by matching the observed triplicated waveforms with the theoretical ones. Our results reveal that (1) the 410 km discontinuity beneath the East China Sea is mostly a sharp boundary with a small-scale uplift of 8-15 km and a gradient boundary up to 20 km in the most southern part, and (2) there exist a low velocity layer atop the 410 km discontinuity with the thickness of 50-62 km and P-wave velocity decrease of 0.5%-1.5%, and (3) a high velocity anomaly with P-wave decrease of 1.0%-3.0% below 440 km. Combining with the previous topographic results in this area, we speculate that the high velocity anomaly is relevant to the stagnancy of the western Pacific slab in the mantle transition zone, the decomposition of phase E in the slab results in the increase of water content, which would cause the uplift of the 410 km discontinuity, and the low velocity layer atop the discontinuity should be related to the partial melting of the mantle peridotite induced by the dehydration of the hydrous minerals.

  3. Retrieving rupture history using waveform inversions in time sequence

    Science.gov (United States)

    Yi, L.; Xu, C.; Zhang, X.

    2017-12-01

    The rupture history of large earthquakes is generally regenerated using the waveform inversion through utilizing seismological waveform records. In the waveform inversion, based on the superposition principle, the rupture process is linearly parameterized. After discretizing the fault plane into sub-faults, the local source time function of each sub-fault is usually parameterized using the multi-time window method, e.g., mutual overlapped triangular functions. Then the forward waveform of each sub-fault is synthesized through convoluting the source time function with its Green function. According to the superposition principle, these forward waveforms generated from the fault plane are summarized in the recorded waveforms after aligning the arrival times. Then the slip history is retrieved using the waveform inversion method after the superposing of all forward waveforms for each correspond seismological waveform records. Apart from the isolation of these forward waveforms generated from each sub-fault, we also realize that these waveforms are gradually and sequentially superimposed in the recorded waveforms. Thus we proposed a idea that the rupture model is possibly detachable in sequent rupture times. According to the constrained waveform length method emphasized in our previous work, the length of inverted waveforms used in the waveform inversion is objectively constrained by the rupture velocity and rise time. And one essential prior condition is the predetermined fault plane that limits the duration of rupture time, which means the waveform inversion is restricted in a pre-set rupture duration time. Therefore, we proposed a strategy to inverse the rupture process sequentially using the progressively shift rupture times as the rupture front expanding in the fault plane. And we have designed a simulation inversion to test the feasibility of the method. Our test result shows the prospect of this idea that requiring furthermore investigation.

  4. Methods in mummy research

    DEFF Research Database (Denmark)

    Lynnerup, Niels

    2009-01-01

    Mummies are human remains with preservation of non-bony tissue. Many mummy studies focus on the development and application of non-destructive methods for examining mummies, including radiography, CT-scanning with advanced 3-dimensional visualisations, and endoscopic techniques, as well as minima......Mummies are human remains with preservation of non-bony tissue. Many mummy studies focus on the development and application of non-destructive methods for examining mummies, including radiography, CT-scanning with advanced 3-dimensional visualisations, and endoscopic techniques, as well...... as minimally-destructive chemical, physical and biological methods for, e.g., stable isotopes, trace metals and DNA....

  5. Research Methods in Sociolinguistics

    Science.gov (United States)

    Hernández-Campoy, Juan Manuel

    2014-01-01

    The development of Sociolinguistics has been qualitatively and quantitatively outstanding within Linguistic Science since its beginning in the 1950s, with a steady growth in both theoretical and methodological developments as well as in its interdisciplinary directions within the spectrum of language and society. Field methods in sociolinguistic…

  6. Developed vibration waveform monitoring unit for CBM

    International Nuclear Information System (INIS)

    Hamada, T.; Hotsuta, K.; Hirose, I.; Morita, E.

    2007-01-01

    In nuclear power plants, many rotating machines such as pumps and fans are in use. Shikoku Research Institute Inc. has recently developed easy-to-use tools to facilitate the maintenance of such equipment. They include a battery-operated vibration waveform monitoring unit which allows unmanned vibration monitoring on a regular basis and data collection even from intermittently operating equipment, a waveform data collector which can be used for easy collection, storage, control, and analysis of raw vibration waveform data during normal operation, and vibration analysis and evaluation tools. A combination of these tools has a high potential for optimization of rotating equipment maintenance. (author)

  7. Multifunction waveform generator for EM receiver testing

    Science.gov (United States)

    Chen, Kai; Jin, Sheng; Deng, Ming

    2018-01-01

    In many electromagnetic (EM) methods - such as magnetotelluric, spectral-induced polarization (SIP), time-domain-induced polarization (TDIP), and controlled-source audio magnetotelluric (CSAMT) methods - it is important to evaluate and test the EM receivers during their development stage. To assess the performance of the developed EM receivers, controlled synthetic data that simulate the observed signals in different modes are required. In CSAMT and SIP mode testing, the waveform generator should use the GPS time as the reference for repeating schedule. Based on our testing, the frequency range, frequency precision, and time synchronization of the currently available function waveform generators on the market are deficient. This paper presents a multifunction waveform generator with three waveforms: (1) a wideband, low-noise electromagnetic field signal to be used for magnetotelluric, audio-magnetotelluric, and long-period magnetotelluric studies; (2) a repeating frequency sweep square waveform for CSAMT and SIP studies; and (3) a positive-zero-negative-zero signal that contains primary and secondary fields for TDIP studies. In this paper, we provide the principles of the above three waveforms along with a hardware design for the generator. Furthermore, testing of the EM receiver was conducted with the waveform generator, and the results of the experiment were compared with those calculated from the simulation and theory in the frequency band of interest.

  8. Sparse Frequency Waveform Design for Radar-Embedded Communication

    Directory of Open Access Journals (Sweden)

    Chaoyun Mai

    2016-01-01

    Full Text Available According to the Tag application with function of covert communication, a method for sparse frequency waveform design based on radar-embedded communication is proposed. Firstly, sparse frequency waveforms are designed based on power spectral density fitting and quasi-Newton method. Secondly, the eigenvalue decomposition of the sparse frequency waveform sequence is used to get the dominant space. Finally the communication waveforms are designed through the projection of orthogonal pseudorandom vectors in the vertical subspace. Compared with the linear frequency modulation waveform, the sparse frequency waveform can further improve the bandwidth occupation of communication signals, thus achieving higher communication rate. A certain correlation exists between the reciprocally orthogonal communication signals samples and the sparse frequency waveform, which guarantees the low SER (signal error rate and LPI (low probability of intercept. The simulation results verify the effectiveness of this method.

  9. Wavelet-Based Signal Processing of Electromagnetic Pulse Generated Waveforms

    National Research Council Canada - National Science Library

    Ardolino, Richard S

    2007-01-01

    This thesis investigated and compared alternative signal processing techniques that used wavelet-based methods instead of traditional frequency domain methods for processing measured electromagnetic pulse (EMP) waveforms...

  10. Regression methods for medical research

    CERN Document Server

    Tai, Bee Choo

    2013-01-01

    Regression Methods for Medical Research provides medical researchers with the skills they need to critically read and interpret research using more advanced statistical methods. The statistical requirements of interpreting and publishing in medical journals, together with rapid changes in science and technology, increasingly demands an understanding of more complex and sophisticated analytic procedures.The text explains the application of statistical models to a wide variety of practical medical investigative studies and clinical trials. Regression methods are used to appropriately answer the

  11. Tourism research and audio methods

    DEFF Research Database (Denmark)

    Jensen, Martin Trandberg

    2016-01-01

    • Audio methods enriches sensuous tourism ethnographies. • The note suggests five research avenues for future auditory scholarship. • Sensuous tourism research has neglected the role of sounds in embodied tourism experiences.......• Audio methods enriches sensuous tourism ethnographies. • The note suggests five research avenues for future auditory scholarship. • Sensuous tourism research has neglected the role of sounds in embodied tourism experiences....

  12. Extraction of microseismic waveforms characteristics prior to rock burst using Hilbert-Huang transform

    Science.gov (United States)

    Li, Xuelong; Li, Zhonghui; Wang, Enyuan; Feng, Junjun; Chen, Liang; Li, Nan; Kong, Xiangguo

    2016-09-01

    This study provides a new research idea concerning rock burst prediction. The characteristics of microseismic (MS) waveforms prior to and during the rock burst were studied through the Hilbert-Huang transform (HHT). In order to demonstrate the advantage of the MS features extraction based on HHT, the conventional analysis method (Fourier transform) was also used to make a comparison. The results show that HHT is simple and reliable, and could extract in-depth information about the characteristics of MS waveforms. About 10 days prior to the rock burst, the main frequency of MS waveforms transforms from the high-frequency to low-frequency. What's more, the waveforms energy also presents accumulation characteristic. Based on our study results, it can be concluded that the MS signals analysis through HHT could provide valuable information about the coal or rock deformation and fracture.

  13. Participatory Methods in Arctic Research

    DEFF Research Database (Denmark)

    Faber, Louise

    2018-01-01

    collection, analysis and conclusions and / or knowledge dissemination. The book aims to collect and share experiences from researchers active in engaging research in the Arctic. The articles reflect on the inclusive methods used in the Arctic research, on the cause and purpose thereof, while the methods......This book is a collection of articles written by researchers at Aalborg University, affiliated with AAU Arctic. The articles are about how the researchers in their respective projects work with stakeholders and citizens in different ways, for example in connection with problem formulation, data...... are exemplified to serve as inspiration for other researchers....

  14. Experimental Methods in Media Research

    NARCIS (Netherlands)

    C.W. Handke (Christian); C. Herzog (Christian)

    2017-01-01

    textabstractCausal effects are a prime concern in media policy research, and experimental research designs are widely regarded as the most effective way to identify and gauge causality. Nevertheless, explicit applications of experimental methods are rare in media policy research. This chapter

  15. Multiples waveform inversion

    KAUST Repository

    Zhang, Dongliang

    2013-01-01

    To increase the illumination of the subsurface and to eliminate the dependency of FWI on the source wavelet, we propose multiples waveform inversion (MWI) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. These virtual sources are used to numerically generate downgoing wavefields that are correlated with the backprojected surface-related multiples to give the migration image. Since the recorded data are treated as the virtual sources, knowledge of the source wavelet is not required, and the subsurface illumination is greatly enhanced because the entire free surface acts as an extended source compared to the radiation pattern of a traditional point source. Numerical tests on the Marmousi2 model show that the convergence rate and the spatial resolution of MWI is, respectively, faster and more accurate then FWI. The potential pitfall with this method is that the multiples undergo more than one roundtrip to the surface, which increases attenuation and reduces spatial resolution. This can lead to less resolved tomograms compared to conventional FWI. The possible solution is to combine both FWI and MWI in inverting for the subsurface velocity distribution.

  16. Tsunami simulation method initiated from waveforms observed by ocean bottom pressure sensors for real-time tsunami forecast; Applied for 2011 Tohoku Tsunami

    Science.gov (United States)

    Tanioka, Yuichiro

    2017-04-01

    After tsunami disaster due to the 2011 Tohoku-oki great earthquake, improvement of the tsunami forecast has been an urgent issue in Japan. National Institute of Disaster Prevention is installing a cable network system of earthquake and tsunami observation (S-NET) at the ocean bottom along the Japan and Kurile trench. This cable system includes 125 pressure sensors (tsunami meters) which are separated by 30 km. Along the Nankai trough, JAMSTEC already installed and operated the cable network system of seismometers and pressure sensors (DONET and DONET2). Those systems are the most dense observation network systems on top of source areas of great underthrust earthquakes in the world. Real-time tsunami forecast has depended on estimation of earthquake parameters, such as epicenter, depth, and magnitude of earthquakes. Recently, tsunami forecast method has been developed using the estimation of tsunami source from tsunami waveforms observed at the ocean bottom pressure sensors. However, when we have many pressure sensors separated by 30km on top of the source area, we do not need to estimate the tsunami source or earthquake source to compute tsunami. Instead, we can initiate a tsunami simulation from those dense tsunami observed data. Observed tsunami height differences with a time interval at the ocean bottom pressure sensors separated by 30 km were used to estimate tsunami height distribution at a particular time. In our new method, tsunami numerical simulation was initiated from those estimated tsunami height distribution. In this paper, the above method is improved and applied for the tsunami generated by the 2011 Tohoku-oki great earthquake. Tsunami source model of the 2011 Tohoku-oki great earthquake estimated using observed tsunami waveforms, coseimic deformation observed by GPS and ocean bottom sensors by Gusman et al. (2012) is used in this study. The ocean surface deformation is computed from the source model and used as an initial condition of tsunami

  17. DISECA - A Matlab code for dispersive waveform calculations

    Czech Academy of Sciences Publication Activity Database

    Gaždová, Renata; Vilhelm, J.

    2011-01-01

    Roč. 38, č. 4 (2011), s. 526-531 ISSN 0266-352X R&D Projects: GA AV ČR IAA300460705 Institutional research plan: CEZ:AV0Z30460519 Keywords : velocity dispersion * synthetic waveform * seismic method Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.987, year: 2011 http://www.sciencedirect.com/science/article/pii/S0266352X11000425

  18. Performance Prediction of Constrained Waveform Design for Adaptive Radar

    Science.gov (United States)

    2016-11-01

    the famous Woodward quote, having a ubiquitous feeling for all radar waveform design (and performance prediction) researchers , that is found at the end...discuss research that develops performance prediction models to quantify the impact on SINR when an amplitude constraint is placed on a radar waveform...optimize the radar perfor- mance for the particular scenario and tasks. There have also been several survey papers on various topics in waveform design for

  19. Workflows for Full Waveform Inversions

    Science.gov (United States)

    Boehm, Christian; Krischer, Lion; Afanasiev, Michael; van Driel, Martin; May, Dave A.; Rietmann, Max; Fichtner, Andreas

    2017-04-01

    Despite many theoretical advances and the increasing availability of high-performance computing clusters, full seismic waveform inversions still face considerable challenges regarding data and workflow management. While the community has access to solvers which can harness modern heterogeneous computing architectures, the computational bottleneck has fallen to these often manpower-bounded issues that need to be overcome to facilitate further progress. Modern inversions involve huge amounts of data and require a tight integration between numerical PDE solvers, data acquisition and processing systems, nonlinear optimization libraries, and job orchestration frameworks. To this end we created a set of libraries and applications revolving around Salvus (http://salvus.io), a novel software package designed to solve large-scale full waveform inverse problems. This presentation focuses on solving passive source seismic full waveform inversions from local to global scales with Salvus. We discuss (i) design choices for the aforementioned components required for full waveform modeling and inversion, (ii) their implementation in the Salvus framework, and (iii) how it is all tied together by a usable workflow system. We combine state-of-the-art algorithms ranging from high-order finite-element solutions of the wave equation to quasi-Newton optimization algorithms using trust-region methods that can handle inexact derivatives. All is steered by an automated interactive graph-based workflow framework capable of orchestrating all necessary pieces. This naturally facilitates the creation of new Earth models and hopefully sparks new scientific insights. Additionally, and even more importantly, it enhances reproducibility and reliability of the final results.

  20. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  1. Seismic waveform classification using deep learning

    Science.gov (United States)

    Kong, Q.; Allen, R. M.

    2017-12-01

    MyShake is a global smartphone seismic network that harnesses the power of crowdsourcing. It has an Artificial Neural Network (ANN) algorithm running on the phone to distinguish earthquake motion from human activities recorded by the accelerometer on board. Once the ANN detects earthquake-like motion, it sends a 5-min chunk of acceleration data back to the server for further analysis. The time-series data collected contains both earthquake data and human activity data that the ANN confused. In this presentation, we will show the Convolutional Neural Network (CNN) we built under the umbrella of supervised learning to find out the earthquake waveform. The waveforms of the recorded motion could treat easily as images, and by taking the advantage of the power of CNN processing the images, we achieved very high successful rate to select the earthquake waveforms out. Since there are many non-earthquake waveforms than the earthquake waveforms, we also built an anomaly detection algorithm using the CNN. Both these two methods can be easily extended to other waveform classification problems.

  2. Mixed-Methods Research Methodologies

    Science.gov (United States)

    Terrell, Steven R.

    2012-01-01

    Mixed-Method studies have emerged from the paradigm wars between qualitative and quantitative research approaches to become a widely used mode of inquiry. Depending on choices made across four dimensions, mixed-methods can provide an investigator with many design choices which involve a range of sequential and concurrent strategies. Defining…

  3. High Performance Harmonic Isolation By Means of The Single-phase Series Active Filter Employing The Waveform Reconstruction Method

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    current sampling delay reduction method (SDRM), a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous reference frame based methods. The analytical, simulation, and experimental studies of a 2...

  4. A fast and reliable method for simultaneous waveform, amplitude and latency estimation of single-trial EEG/MEG data.

    Directory of Open Access Journals (Sweden)

    Wouter D Weeda

    Full Text Available The amplitude and latency of single-trial EEG/MEG signals may provide valuable information concerning human brain functioning. In this article we propose a new method to reliably estimate single-trial amplitude and latency of EEG/MEG signals. The advantages of the method are fourfold. First, no a-priori specified template function is required. Second, the method allows for multiple signals that may vary independently in amplitude and/or latency. Third, the method is less sensitive to noise as it models data with a parsimonious set of basis functions. Finally, the method is very fast since it is based on an iterative linear least squares algorithm. A simulation study shows that the method yields reliable estimates under different levels of latency variation and signal-to-noise ratioÕs. Furthermore, it shows that the existence of multiple signals can be correctly determined. An application to empirical data from a choice reaction time study indicates that the method describes these data accurately.

  5. Extension of frequency-based dissimilarity for retrieving similar plasma waveforms

    International Nuclear Information System (INIS)

    Hochin, Teruhisa; Koyama, Katsumasa; Nakanishi, Hideya; Kojima, Mamoru

    2008-01-01

    Some computer-aided assistance in finding the waveforms similar to a waveform has become indispensable for accelerating data analysis in the plasma experiments. For the slowly-varying waveforms and those having time-sectional oscillation patterns, the methods using the Fourier series coefficients of waveforms in calculating the dissimilarity have successfully improved the performance in retrieving similar waveforms. This paper treats severely-varying waveforms, and proposes two extensions to the dissimilarity of waveforms. The first extension is to capture the difference of the importance of the Fourier series coefficients of waveforms against frequency. The second extension is to consider the outlines of waveforms. The correctness of the extended dissimilarity is experimentally evaluated by using the metrics used in evaluating that of the information retrieval, i.e. precision and recall. The experimental results show that the extended dissimilarity could improve the correctness of the similarity retrieval of plasma waveforms

  6. Radial artery pulse waveform analysis based on curve fitting using discrete Fourier series.

    Science.gov (United States)

    Jiang, Zhixing; Zhang, David; Lu, Guangming

    2018-04-19

    Radial artery pulse diagnosis has been playing an important role in traditional Chinese medicine (TCM). For its non-invasion and convenience, the pulse diagnosis has great significance in diseases analysis of modern medicine. The practitioners sense the pulse waveforms in patients' wrist to make diagnoses based on their non-objective personal experience. With the researches of pulse acquisition platforms and computerized analysis methods, the objective study on pulse diagnosis can help the TCM to keep up with the development of modern medicine. In this paper, we propose a new method to extract feature from pulse waveform based on discrete Fourier series (DFS). It regards the waveform as one kind of signal that consists of a series of sub-components represented by sine and cosine (SC) signals with different frequencies and amplitudes. After the pulse signals are collected and preprocessed, we fit the average waveform for each sample using discrete Fourier series by least squares. The feature vector is comprised by the coefficients of discrete Fourier series function. Compared with the fitting method using Gaussian mixture function, the fitting errors of proposed method are smaller, which indicate that our method can represent the original signal better. The classification performance of proposed feature is superior to the other features extracted from waveform, liking auto-regression model and Gaussian mixture model. The coefficients of optimized DFS function, who is used to fit the arterial pressure waveforms, can obtain better performance in modeling the waveforms and holds more potential information for distinguishing different psychological states. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Full waveform inversion based on scattering angle enrichment with application to real dataset

    KAUST Repository

    Wu, Zedong; Alkhalifah, Tariq Ali

    2015-01-01

    Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI). However, the drawback of the existing RWI methods is inability to utilize diving waves and the extra sensitivity

  8. Behavioral Methods in Consciousness Research

    DEFF Research Database (Denmark)

    that the research literature has expanded greatly, particularly in cognitive neuroscience and cognitive science. Interestingly, this scientific work has made use of a wide variety of different methods without much consensus on how one might in fact measure subjective consciousness. This situation makes...

  9. Multichannel waveform display system

    International Nuclear Information System (INIS)

    Kolvankar, V.G.

    1989-01-01

    For any multichannel data acquisition system, a multichannel paper chart recorder undoubtedly forms an essential part of the system. When deployed on-line, it instantaneously provides, for visual inspection, hard copies of the signal waveforms on common time base at any desired sensitivity and time resolution. Within the country, only a small range of these strip chart recorder s is available, and under stringent specifications imported recorders are often procured. The cost of such recorders may range from 1 to 5 lakhs of rupees in foreign exchange. A system to provide on the oscilloscope a steady display of multichannel waveforms, refreshed from the digital data stored in the memory is developed. The merits and demerits of the display system are compared with that built around a conventional paper chart recorder. Various illustrations of multichannel seismic event data acquired at Gauribidanur seismic array station are also presented. (author). 2 figs

  10. Wavelet analysis of the impedance cardiogram waveforms

    Science.gov (United States)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  11. Wavelet analysis of the impedance cardiogram waveforms

    International Nuclear Information System (INIS)

    Podtaev, S; Stepanov, R; Dumler, A; Chugainov, S; Tziberkin, K

    2012-01-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt) max ) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  12. Krylov subspace acceleration of waveform relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Lumsdaine, A.; Wu, Deyun [Univ. of Notre Dame, IN (United States)

    1996-12-31

    Standard solution methods for numerically solving time-dependent problems typically begin by discretizing the problem on a uniform time grid and then sequentially solving for successive time points. The initial time discretization imposes a serialization to the solution process and limits parallel speedup to the speedup available from parallelizing the problem at any given time point. This bottleneck can be circumvented by the use of waveform methods in which multiple time-points of the different components of the solution are computed independently. With the waveform approach, a problem is first spatially decomposed and distributed among the processors of a parallel machine. Each processor then solves its own time-dependent subsystem over the entire interval of interest using previous iterates from other processors as inputs. Synchronization and communication between processors take place infrequently, and communication consists of large packets of information - discretized functions of time (i.e., waveforms).

  13. Resolution analysis in full waveform inversion

    NARCIS (Netherlands)

    Fichtner, A.; Trampert, J.

    2011-01-01

    We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure. The method rests on (1) the local quadratic

  14. Effects of Conjugate Gradient Methods and Step-Length Formulas on the Multiscale Full Waveform Inversion in Time Domain: Numerical Experiments

    Science.gov (United States)

    Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José; Liu, Qinya; Zhou, Bing

    2017-05-01

    We carry out full waveform inversion (FWI) in time domain based on an alternative frequency-band selection strategy that allows us to implement the method with success. This strategy aims at decomposing the seismic data within partially overlapped frequency intervals by carrying out a concatenated treatment of the wavelet to largely avoid redundant frequency information to adapt to wavelength or wavenumber coverage. A pertinent numerical test proves the effectiveness of this strategy. Based on this strategy, we comparatively analyze the effects of update parameters for the nonlinear conjugate gradient (CG) method and step-length formulas on the multiscale FWI through several numerical tests. The investigations of up to eight versions of the nonlinear CG method with and without Gaussian white noise make clear that the HS (Hestenes and Stiefel in J Res Natl Bur Stand Sect 5:409-436, 1952), CD (Fletcher in Practical methods of optimization vol. 1: unconstrained optimization, Wiley, New York, 1987), and PRP (Polak and Ribière in Revue Francaise Informat Recherche Opertionelle, 3e Année 16:35-43, 1969; Polyak in USSR Comput Math Math Phys 9:94-112, 1969) versions are more efficient among the eight versions, while the DY (Dai and Yuan in SIAM J Optim 10:177-182, 1999) version always yields inaccurate result, because it overestimates the deeper parts of the model. The application of FWI algorithms using distinct step-length formulas, such as the direct method ( Direct), the parabolic search method ( Search), and the two-point quadratic interpolation method ( Interp), proves that the Interp is more efficient for noise-free data, while the Direct is more efficient for Gaussian white noise data. In contrast, the Search is less efficient because of its slow convergence. In general, the three step-length formulas are robust or partly insensitive to Gaussian white noise and the complexity of the model. When the initial velocity model deviates far from the real model or the

  15. SCA Waveform Development for Space Telemetry

    Science.gov (United States)

    Mortensen, Dale J.; Kifle, Multi; Hall, C. Steve; Quinn, Todd M.

    2004-01-01

    The NASA Glenn Research Center is investigating and developing suitable reconfigurable radio architectures for future NASA missions. This effort is examining software-based open-architectures for space based transceivers, as well as common hardware platform architectures. The Joint Tactical Radio System's (JTRS) Software Communications Architecture (SCA) is a candidate for the software approach, but may need modifications or adaptations for use in space. An in-house SCA compliant waveform development focuses on increasing understanding of software defined radio architectures and more specifically the JTRS SCA. Space requirements put a premium on size, mass, and power. This waveform development effort is key to evaluating tradeoffs with the SCA for space applications. Existing NASA telemetry links, as well as Space Exploration Initiative scenarios, are the basis for defining the waveform requirements. Modeling and simulations are being developed to determine signal processing requirements associated with a waveform and a mission-specific computational burden. Implementation of the waveform on a laboratory software defined radio platform is proceeding in an iterative fashion. Parallel top-down and bottom-up design approaches are employed.

  16. WFCatalog: A catalogue for seismological waveform data

    Science.gov (United States)

    Trani, Luca; Koymans, Mathijs; Atkinson, Malcolm; Sleeman, Reinoud; Filgueira, Rosa

    2017-09-01

    This paper reports advances in seismic waveform description and discovery leading to a new seismological service and presents the key steps in its design, implementation and adoption. This service, named WFCatalog, which stands for waveform catalogue, accommodates features of seismological waveform data. Therefore, it meets the need for seismologists to be able to select waveform data based on seismic waveform features as well as sensor geolocations and temporal specifications. We describe the collaborative design methods and the technical solution showing the central role of seismic feature catalogues in framing the technical and operational delivery of the new service. Also, we provide an overview of the complex environment wherein this endeavour is scoped and the related challenges discussed. As multi-disciplinary, multi-organisational and global collaboration is necessary to address today's challenges, canonical representations can provide a focus for collaboration and conceptual tools for agreeing directions. Such collaborations can be fostered and formalised by rallying intellectual effort into the design of novel scientific catalogues and the services that support them. This work offers an example of the benefits generated by involving cross-disciplinary skills (e.g. data and domain expertise) from the early stages of design, and by sustaining the engagement with the target community throughout the delivery and deployment process.

  17. Principles of waveform diversity and design

    CERN Document Server

    Wicks, Michael

    2011-01-01

    This is the first book to discuss current and future applications of waveform diversity and design in subjects such as radar and sonar, communications systems, passive sensing, and many other technologies. Waveform diversity allows researchers and system designers to optimize electromagnetic and acoustic systems for sensing, communications, electronic warfare or combinations thereof. This book enables solutions to problems, explaining how each system performs its own particular function, as well as how it is affected by other systems and how those other systems may likewise be affected. It is

  18. Seismic waveform modeling over cloud

    Science.gov (United States)

    Luo, Cong; Friederich, Wolfgang

    2016-04-01

    With the fast growing computational technologies, numerical simulation of seismic wave propagation achieved huge successes. Obtaining the synthetic waveforms through numerical simulation receives an increasing amount of attention from seismologists. However, computational seismology is a data-intensive research field, and the numerical packages usually come with a steep learning curve. Users are expected to master considerable amount of computer knowledge and data processing skills. Training users to use the numerical packages, correctly access and utilize the computational resources is a troubled task. In addition to that, accessing to HPC is also a common difficulty for many users. To solve these problems, a cloud based solution dedicated on shallow seismic waveform modeling has been developed with the state-of-the-art web technologies. It is a web platform integrating both software and hardware with multilayer architecture: a well designed SQL database serves as the data layer, HPC and dedicated pipeline for it is the business layer. Through this platform, users will no longer need to compile and manipulate various packages on the local machine within local network to perform a simulation. By providing users professional access to the computational code through its interfaces and delivering our computational resources to the users over cloud, users can customize the simulation at expert-level, submit and run the job through it.

  19. Waveform Design for Wireless Power Transfer

    Science.gov (United States)

    Clerckx, Bruno; Bayguzina, Ekaterina

    2016-12-01

    Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity of the rectenna and compare with a linear model conventionally used in the literature. We then use those models to design novel multisine waveforms that are adaptive to the channel state information (CSI). Interestingly, while the linear model favours narrowband transmission with all the power allocated to a single frequency, the non-linear model favours a power allocation over multiple frequencies. Through realistic simulations, waveforms designed based on the non-linear model are shown to provide significant gains (in terms of harvested DC power) over those designed based on the linear model and over non-adaptive waveforms. We also compute analytically the theoretical scaling laws of the harvested energy for various waveforms as a function of the number of sinewaves and transmit antennas. Those scaling laws highlight the benefits of CSI knowledge at the transmitter in WPT and of a WPT design based on a non-linear rectenna model over a linear model. Results also motivate the study of a promising architecture relying on large-scale multisine multi-antenna waveforms for WPT. As a final note, results stress the importance of modeling and accounting for the non-linearity of the rectenna in any system design involving wireless power.

  20. Electronics via waveform analysis

    CERN Document Server

    Craig, Edwin C

    1993-01-01

    The author believes that a good basic understanding of electronics can be achieved by detailed visual analyses of the actual voltage waveforms present in selected circuits. The voltage waveforms included in this text were photographed using a 35-rrun camera in an attempt to make the book more attractive. This book is intended for the use of students with a variety of backgrounds. For this reason considerable material has been placed in the Appendix for those students who find it useful. The Appendix includes many basic electricity and electronic concepts as well as mathematical derivations that are not vital to the understanding of the circuit being discussed in the text at that time. Also some derivations might be so long that, if included in the text, it could affect the concentration of the student on the circuit being studied. The author has tried to make the book comprehensive enough so that a student could use it as a self-study course, providing one has access to adequate laboratory equipment.

  1. Evaluating a small footprint, waveform-resolving lidar over coastal vegetation communities

    Science.gov (United States)

    Nayegandhl, A.; Brock, J.C.; Wright, C.W.; O'Connell, M. J.

    2006-01-01

    NASA's Experimental Advanced Airborne Research Lidar (EAARL) is a raster-scanning, waveform-resolving, green-wavelength (532 nm) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor records the time history of the return waveform within a small footprint (20 cm diameter) for each laser pulse, enabling characterization of vegetation canopy structure and "bare earth" topography under a variety of vegetation types. A collection of individual waveforms combined within a synthesized large footprint was used to define three metrics: canopy height (CH), canopy reflection ratio (CRR), and height of median energy (HOME). Bare Earth Elevation (BEE) metric was derived using the individual small-footprint waveforms. All four metrics were tested for reproducibility, which resulted in an average of 95 percent correspondence within two standard deviations of the mean. CH and BEE values were also tested for accuracy using ground-truth data. The results presented in this paper show that combining several individual small-footprint laser pulses to define a composite "large-footprint" waveform is a possible method to depict the vertical structure of a vegetation canopy. ?? 2006 American Society for Photogrammetry and Remote Sensing.

  2. Integration and interpolation of sampled waveforms

    International Nuclear Information System (INIS)

    Stearns, S.D.

    1978-01-01

    Methods for integrating, interpolating, and improving the signal-to-noise ratio of digitized waveforms are discussed with regard to seismic data from underground tests. The frequency-domain integration method and the digital interpolation method of Schafer and Rabiner are described and demonstrated using test data. The use of bandpass filtering for noise reduction is also demonstrated. With these methods, a backlog of seismic test data has been successfully processed

  3. Methods and Methods' Debates within Consumption Research

    DEFF Research Database (Denmark)

    Halkier, Bente

    2017-01-01

    This chapter takes an open look at how researchers are using new topographies, technologies, and technocultural rituals and routines in order to reconceptualize what market actors are and do, and most especially, how they should be studied. We are interested in the latest developments in consumer...... ethnography, as we have experienced and visualized them being practices in our native fields of anthropology, marketing and consumer research, and as it has touched upon industry market researchers and their workings. We do not rehash classic treatments easily available to interested scholars (e.g. Arnould...

  4. A new method to detect cerebral blood flow waveform in synchrony with chest compression by near-infrared spectroscopy during CPR.

    Science.gov (United States)

    Koyama, Yasuaki; Wada, Takafumi; Lohman, Brandon D; Takamatsu, Yuka; Matsumoto, Junichi; Fujitani, Shigeki; Taira, Yasuhiko

    2013-10-01

    The objective of the study is to demonstrate the utility of near-infrared spectroscopy (NIRS) in evaluating chest compression (CC) quality in cardiac arrest (CA) patients as well as determine its prognosis predictive value. We present a nonconsecutive case series of adult patients with CA whose cardiopulmonary resuscitation (CPR) was monitored with NIRS and collected the total hemoglobin concentration change (ΔcHb), the tissue oxygen index (TOI), and the ΔTOI to assess CC quality in a noninvasive fashion. During CPR, ΔcHb displayed waveforms monitor, which we regarded as a surrogate for CC quality. Total hemoglobin concentration change waveforms responded accurately to variations or cessations of CCs. In addition, a TOI greater than 40% measured upon admission appears to be significant in predicting patient's outcome. Of 15 patients, 6 had a TOI greater than 40% measured upon admission, and 67% of the latter were in return of spontaneous circulation after CPR and were found to be significantly different between return of spontaneous circulation and death (P = .047; P < .05). Near-infrared spectroscopy reliably assesses the quality of CCs in patients with CA demonstrated by synchronous waveforms during CPR and possible prognostic predictive value, although further investigation is warranted. © 2013 Elsevier Inc. All rights reserved.

  5. Waveform digitizing at 500 MHz

    International Nuclear Information System (INIS)

    Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.

    1988-01-01

    Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10 -10 . To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the (π + → μ + ν, μ + → e + ν/bar /nu//) decay sequence in scintillator. We report on the design and construction of 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February-May 1988 run showing performance of the system for the observation of the above decay. 8 figs

  6. Waveform digitizing at 500 MHz

    International Nuclear Information System (INIS)

    Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.

    1988-01-01

    Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10/sup /minus/10/. To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the π + → μ + → e + ν/bar /nu// decay sequence in scintillator. We report on the design and construction of over 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February--May 1988 run showing performance of the system for the observation of the above decay. 9 figs

  7. Waveform Sampler CAMAC Module

    International Nuclear Information System (INIS)

    Freytag, D.R.; Haller, G.M.; Kang, H.; Wang, J.

    1985-09-01

    A Waveform Sampler Module (WSM) for the measurement of signal shapes coming from the multi-hit drift chambers of the SLAC SLC detector is described. The module uses a high speed, high resolution analog storage device (AMU) developed in collaboration between SLAC and Stanford University. The AMU devices together with high speed TTL clocking circuitry are packaged in a hybrid which is also suitable for mounting on the detector. The module is in CAMAC format and provides eight signal channels, each recording signal amplitude versus time in 512 cells at a sampling rate of up to 360 MHz. Data are digitized by a 12-bit ADC with a 1 μs conversion time and stored in an on-board memory accessible through CAMAC

  8. A new optimization approach for source-encoding full-waveform inversion

    NARCIS (Netherlands)

    Moghaddam, P.P.; Keers, H.; Herrmann, F.J.; Mulder, W.A.

    2013-01-01

    Waveform inversion is the method of choice for determining a highly heterogeneous subsurface structure. However, conventional waveform inversion requires that the wavefield for each source is computed separately. This makes it very expensive for realistic 3D seismic surveys. Source-encoding waveform

  9. Classification of morphologic changes in photoplethysmographic waveforms

    Directory of Open Access Journals (Sweden)

    Tigges Timo

    2016-09-01

    Full Text Available An ever increasing number of research is examining the question to what extent physiological information beyond the blood oxygen saturation could be drawn from the photoplethysmogram. One important approach to elicit that information from the photoplethysmogram is the analysis of its waveform. One prominent example for the value of photoplethysmographic waveform analysis in cardiovascular monitoring that has emerged is hemodynamic compensation assessment in the peri-operative setting or trauma situations, as digital pulse waveform dynamically changes with alterations in vascular tone or pulse wave velocity. In this work, we present an algorithm based on modern machine learning techniques that automatically finds individual digital volume pulses in photoplethysmographic signals and sorts them into one of the pulse classes defined by Dawber et al. We evaluate our approach based on two major datasets – a measurement study that we conducted ourselves as well as data from the PhysioNet MIMIC II database. As the results are satisfying we could demonstrate the capabilities of classification algorithms in the automated assessment of the digital volume pulse waveform measured by photoplethysmographic devices.

  10. Colocated MIMO Radar: Beamforming, Waveform design, and Target Parameter Estimation

    KAUST Repository

    Jardak, Seifallah

    2014-04-01

    Thanks to its improved capabilities, the Multiple Input Multiple Output (MIMO) radar is attracting the attention of researchers and practitioners alike. Because it transmits orthogonal or partially correlated waveforms, this emerging technology outperformed the phased array radar by providing better parametric identifiability, achieving higher spatial resolution, and designing complex beampatterns. To avoid jamming and enhance the signal to noise ratio, it is often interesting to maximize the transmitted power in a given region of interest and minimize it elsewhere. This problem is known as the transmit beampattern design and is usually tackled as a two-step process: a transmit covariance matrix is firstly designed by minimizing a convex optimization problem, which is then used to generate practical waveforms. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method maps easily generated Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability density function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. The second part of this thesis covers the topic of target parameter estimation. To determine the reflection coefficient, spatial location, and Doppler shift of a target, maximum likelihood estimation yields the best performance. However, it requires a two dimensional search problem. Therefore, its computational complexity is prohibitively high. So, we proposed a reduced complexity and optimum performance algorithm which allows the two dimensional fast Fourier transform to jointly estimate the spatial location

  11. Nuclear methods in environmental and energy research

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, J. R. [ed.

    1977-01-01

    The topics considered in the seven sessions were nuclear methods in atmospheric research; nuclear and atomic methodology; nuclear methods in tracer applications; energy exploration, production, and utilization; nuclear methods in environmental monitoring; nuclear methods in water research; and nuclear methods in biological research. Individual abstracts were prepared for each paper. (JSR)

  12. Waveform Catalog, Extreme Mass Ratio Binary (Capture)

    Data.gov (United States)

    National Aeronautics and Space Administration — Numerically-generated gravitational waveforms for circular inspiral into Kerr black holes. These waveforms were developed using Scott Hughes' black hole perturbation...

  13. Source-independent elastic waveform inversion using a logarithmic wavefield

    KAUST Repository

    Choi, Yun Seok

    2012-01-01

    The logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating the source wavelet in the logarithmic waveform inversion, we developed a source-independent logarithmic waveform inversion algorithm. In this inversion algorithm, we first normalize the wavefields with the reference wavefield to remove the source wavelet, and then take the logarithm of the normalized wavefields. Based on the properties of the logarithm, we define three types of misfit functions using the following methods: combination of amplitude and phase, amplitude-only, and phase-only. In the inversion, the gradient is computed using the back-propagation formula without directly calculating the Jacobian matrix. We apply our algorithm to noise-free and noise-added synthetic data generated for the modified version of elastic Marmousi2 model, and compare the results with those of the source-estimation logarithmic waveform inversion. For the noise-free data, the source-independent algorithms yield velocity models close to true velocity models. For random-noise data, the source-estimation logarithmic waveform inversion yields better results than the source-independent method, whereas for coherent-noise data, the results are reversed. Numerical results show that the source-independent and source-estimation logarithmic waveform inversion methods have their own merits for random- and coherent-noise data. © 2011.

  14. SURFACE FITTING FILTERING OF LIDAR POINT CLOUD WITH WAVEFORM INFORMATION

    Directory of Open Access Journals (Sweden)

    S. Xing

    2017-09-01

    Full Text Available Full-waveform LiDAR is an active technology of photogrammetry and remote sensing. It provides more detailed information about objects along the path of a laser pulse than discrete-return topographic LiDAR. The point cloud and waveform information with high quality can be obtained by waveform decomposition, which could make contributions to accurate filtering. The surface fitting filtering method with waveform information is proposed to present such advantage. Firstly, discrete point cloud and waveform parameters are resolved by global convergent Levenberg Marquardt decomposition. Secondly, the ground seed points are selected, of which the abnormal ones are detected by waveform parameters and robust estimation. Thirdly, the terrain surface is fitted and the height difference threshold is determined in consideration of window size and mean square error. Finally, the points are classified gradually with the rising of window size. The filtering process is finished until window size is larger than threshold. The waveform data in urban, farmland and mountain areas from “WATER (Watershed Allied Telemetry Experimental Research” are selected for experiments. Results prove that compared with traditional method, the accuracy of point cloud filtering is further improved and the proposed method has highly practical value.

  15. Mixed methods research in mental health nursing.

    Science.gov (United States)

    Kettles, A M; Creswell, J W; Zhang, W

    2011-08-01

    Mixed methods research is becoming more widely used in order to answer research questions and to investigate research problems in mental health and psychiatric nursing. However, two separate literature searches, one in Scotland and one in the USA, revealed that few mental health nursing studies identified mixed methods research in their titles. Many studies used the term 'embedded' but few studies identified in the literature were mixed methods embedded studies. The history, philosophical underpinnings, definition, types of mixed methods research and associated pragmatism are discussed, as well as the need for mixed methods research. Examples of mental health nursing mixed methods research are used to illustrate the different types of mixed methods: convergent parallel, embedded, explanatory and exploratory in their sequential and concurrent combinations. Implementing mixed methods research is also discussed briefly and the problem of identifying mixed methods research in mental and psychiatric nursing are discussed with some possible solutions to the problem proposed. © 2011 Blackwell Publishing.

  16. Full Waveform Inversion for Reservoir Characterization - A Synthetic Study

    KAUST Repository

    Zabihi Naeini, E.; Kamath, N.; Tsvankin, I.; Alkhalifah, Tariq Ali

    2017-01-01

    Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI

  17. Earthquake Early Warning: Real-time Testing of an On-site Method Using Waveform Data from the Southern California Seismic Network

    Science.gov (United States)

    Solanki, K.; Hauksson, E.; Kanamori, H.; Wu, Y.; Heaton, T.; Boese, M.

    2007-12-01

    We have implemented an on-site early warning algorithm using the infrastructure of the Caltech/USGS Southern California Seismic Network (SCSN). We are evaluating the real-time performance of the software system and the algorithm for rapid assessment of earthquakes. In addition, we are interested in understanding what parts of the SCSN need to be improved to make early warning practical. Our EEW processing system is composed of many independent programs that process waveforms in real-time. The codes were generated by using a software framework. The Pd (maximum displacement amplitude of P wave during the first 3sec) and Tau-c (a period parameter during the first 3 sec) values determined during the EEW processing are being forwarded to the California Integrated Seismic Network (CISN) web page for independent evaluation of the results. The on-site algorithm measures the amplitude of the P-wave (Pd) and the frequency content of the P-wave during the first three seconds (Tau-c). The Pd and the Tau-c values make it possible to discriminate between a variety of events such as large distant events, nearby small events, and potentially damaging nearby events. The Pd can be used to infer the expected maximum ground shaking. The method relies on data from a single station although it will become more reliable if readings from several stations are associated. To eliminate false triggers from stations with high background noise level, we have created per station Pd threshold configuration for the Pd/Tau-c algorithm. To determine appropriate values for the Pd threshold we calculate Pd thresholds for stations based on the information from the EEW logs. We have operated our EEW test system for about a year and recorded numerous earthquakes in the magnitude range from M3 to M5. Two recent examples are a M4.5 earthquake near Chatsworth and a M4.7 earthquake near Elsinore. In both cases, the Pd and Tau-c parameters were determined successfully within 10 to 20 sec of the arrival of the

  18. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    Science.gov (United States)

    Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel

    2014-07-01

    We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a

  19. ADDRESSING RESEARCH DESIGN PROBLEM IN MIXED METHODS RESEARCH

    OpenAIRE

    Hamed ALAVI; Patrycja HĄBEK

    2016-01-01

    Alongside other disciplines in social sciences, management researchers use mixed methods research more and more in conduct of their scientific investigations. Mixed methods approach can also be used in the field of production engineering. In comparison with traditional quantitative and qualitative research methods, reasons behind increasing popularity of mixed research method in management science can be traced in different factors. First of all, any particular discipline in management can be...

  20. Anisotropic wave-equation traveltime and waveform inversion

    KAUST Repository

    Feng, Shihang

    2016-09-06

    The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially performed using the wave-equation traveltime inversion (WT) method. The WT tomograms are then used as starting background models for VTI full waveform inversion. Preliminary numerical tests on synthetic data demonstrate the feasibility of this method for multi-parameter inversion.

  1. Nuclear methods in environmental and energy research

    International Nuclear Information System (INIS)

    Vogt, J.R.

    1980-01-01

    A total of 75 papers were presented on nuclear methods for analysis of environmental and biological samples. Sessions were devoted to software and mathematical methods; nuclear methods in atmospheric and water research; nuclear and atomic methodology; nuclear methods in biology and medicine; and nuclear methods in energy research

  2. Nuclear methods in environmental and energy research

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, J R [ed.

    1980-01-01

    A total of 75 papers were presented on nuclear methods for analysis of environmental and biological samples. Sessions were devoted to software and mathematical methods; nuclear methods in atmospheric and water research; nuclear and atomic methodology; nuclear methods in biology and medicine; and nuclear methods in energy research.

  3. Propagation compensation by waveform predistortion

    Science.gov (United States)

    Halpin, Thomas F.; Urkowitz, Harry; Maron, David E.

    Certain modifications of the Cobra Dane radar are considered, particularly modernization of the waveform generator. For wideband waveforms, the dispersive effects of the ionosphere become increasingly significant. The technique of predistorting the transmitted waveform so that a linear chirp is received after two-way passage is one way to overcome that dispersion. This approach is maintained for the modified system, but with a specific predistortion waveform well suited to the modification. The appropriate form of predistortion was derived in an implicit form of time as a function of frequency. The exact form was approximated by Taylor series and pseudo-Chebyshev approximation. The latter proved better, as demonstrated by the resulting smaller loss in detection sensitivity, less coarsening of range resolution, and a lower peak sidelobe. The effects of error in determining the plasma delay constant were determined and are given in graphical form. A suggestion for in-place determination of the plasma delay constant is given.

  4. Using mixed methods in health research.

    OpenAIRE

    Tariq, S.; Woodman, J.

    2013-01-01

    Mixed methods research is the use of quantitative and qualitative methods in a single study or series of studies. It is an emergent methodology which is increasingly used by health researchers, especially within health services research. There is a growing literature on the theory, design and critical appraisal of mixed methods research. However, there are few papers that summarize this methodological approach for health practitioners who wish to conduct or critically engage with mixed method...

  5. Advanced Waveform Simulation for Seismic Monitoring

    Science.gov (United States)

    2008-09-01

    velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and...ranges out to 10°, including extensive observations of crustal thinning and thickening and various Pnl complexities. Broadband modeling in 1D, 2D...existing models perform in predicting the various regional phases, Rayleigh waves, Love waves, and Pnl waves. Previous events from this Basin-and-Range

  6. Teaching Qualitative Research Methods Using "Undercover Boss"

    Science.gov (United States)

    Graham, LaKresha; Schuwerk, Tara J.

    2017-01-01

    Course(s): Research Methods, Qualitative Research Methods, Organizational Communication, Business Communication. Objectives: After completing this class exercise, students should be able to identify the major components of a qualitative research study, along with the ethical dilemmas that come with doing qualitative research.

  7. Action Research Methods: Plain and Simple

    Science.gov (United States)

    Klein, Sheri R., Ed.

    2012-01-01

    Among the plethora of action research books on the market, there is no one text exclusively devoted to understanding how to acquire and interpret research data. Action Research Methods provides a balanced overview of the quantitative and qualitative methodologies and methods for conducting action research within a variety of educational…

  8. Addressing Research Design Problem in Mixed Methods Research

    Science.gov (United States)

    Alavi, Hamed; Hąbek, Patrycja

    2016-03-01

    Alongside other disciplines in social sciences, management researchers use mixed methods research more and more in conduct of their scientific investigations. Mixed methods approach can also be used in the field of production engineering. In comparison with traditional quantitative and qualitative research methods, reasons behind increasing popularity of mixed research method in management science can be traced in different factors. First of all, any particular discipline in management can be theoretically related to it. Second is that concurrent approach of mixed research method to inductive and deductive research logic provides researchers with opportunity to generate theory and test hypothesis in one study simultaneously. In addition, it provides a better justification for chosen method of investigation and higher validity for obtained answers to research questions. Despite increasing popularity of mixed research methods among management scholars, there is still need for a comprehensive approach to research design typology and process in mixed research method from the perspective of management science. The authors in this paper try to explain fundamental principles of mixed research method, its typology and different steps in its design process.

  9. Nuclear methods in coal research

    International Nuclear Information System (INIS)

    Lyon, W.S.

    1980-01-01

    Nuclear methods, particularly neutron activation analysis (NAA) provide useful information about elemental constituents in coal and fly ash, but often other techniques are required to supplement NAA data. Spark source mass spectrometry and atomic absorption have been studied as methods for determination of certain elements in coal that are not easily measured by NAA. In work concerned with the chemical speciation of elements in fly ash, a number of analytical techniques have been used; these include NAA, chemical etching and separation, optical and electron microscopy and x-ray diffraction

  10. Thermophysical methods in materials research

    International Nuclear Information System (INIS)

    Rohde, M.

    2003-01-01

    Thermophysical properties, namely the thermal conductivity, diffusivity and the heat capacity determine the behavior of every material under heat load. Therefore these properties are important not only for design purposes but also for the development of advanced materials. Within this contribution an overview will be given about measurement techniques for thermophysical properties. Some aspects of materials characterization and process development will be highlighted using selected research results. (orig.)

  11. SeisFlows-Flexible waveform inversion software

    Science.gov (United States)

    Modrak, Ryan T.; Borisov, Dmitry; Lefebvre, Matthieu; Tromp, Jeroen

    2018-06-01

    SeisFlows is an open source Python package that provides a customizable waveform inversion workflow and framework for research in oil and gas exploration, earthquake tomography, medical imaging, and other areas. New methods can be rapidly prototyped in SeisFlows by inheriting from default inversion or migration classes, and code can be tested on 2D examples before application to more expensive 3D problems. Wave simulations must be performed using an external software package such as SPECFEM3D. The ability to interface with external solvers lends flexibility, and the choice of SPECFEM3D as a default option provides optional GPU acceleration and other useful capabilities. Through support for massively parallel solvers and interfaces for high-performance computing (HPC) systems, inversions with thousands of seismic traces and billions of model parameters can be performed. So far, SeisFlows has run on clusters managed by the Department of Defense, Chevron Corp., Total S.A., Princeton University, and the University of Alaska, Fairbanks.

  12. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Ahmed, Sajid

    2016-01-13

    Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.

  13. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Ahmed, Sajid; Alouini, Mohamed-Slim; Jardak, Seifallah

    2016-01-01

    Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.

  14. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    Directory of Open Access Journals (Sweden)

    Scott E. Field

    2014-07-01

    Full Text Available We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform’s value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mc_{fit} online operations, where c_{fit} denotes the fitting function operation count and, typically, m≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 10^{5}M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in

  15. Statistical gravitational waveform models: What to simulate next?

    Science.gov (United States)

    Doctor, Zoheyr; Farr, Ben; Holz, Daniel E.; Pürrer, Michael

    2017-12-01

    Models of gravitational waveforms play a critical role in detecting and characterizing the gravitational waves (GWs) from compact binary coalescences. Waveforms from numerical relativity (NR), while highly accurate, are too computationally expensive to produce to be directly used with Bayesian parameter estimation tools like Markov-chain-Monte-Carlo and nested sampling. We propose a Gaussian process regression (GPR) method to generate reduced-order-model waveforms based only on existing accurate (e.g. NR) simulations. Using a training set of simulated waveforms, our GPR approach produces interpolated waveforms along with uncertainties across the parameter space. As a proof of concept, we use a training set of IMRPhenomD waveforms to build a GPR model in the 2-d parameter space of mass ratio q and equal-and-aligned spin χ1=χ2. Using a regular, equally-spaced grid of 120 IMRPhenomD training waveforms in q ∈[1 ,3 ] and χ1∈[-0.5 ,0.5 ], the GPR mean approximates IMRPhenomD in this space to mismatches below 4.3 ×10-5. Our approach could in principle use training waveforms directly from numerical relativity. Beyond interpolation of waveforms, we also present a greedy algorithm that utilizes the errors provided by our GPR model to optimize the placement of future simulations. In a fiducial test case we find that using the greedy algorithm to iteratively add simulations achieves GPR errors that are ˜1 order of magnitude lower than the errors from using Latin-hypercube or square training grids.

  16. Adaptive phase k-means algorithm for waveform classification

    Science.gov (United States)

    Song, Chengyun; Liu, Zhining; Wang, Yaojun; Xu, Feng; Li, Xingming; Hu, Guangmin

    2018-01-01

    Waveform classification is a powerful technique for seismic facies analysis that describes the heterogeneity and compartments within a reservoir. Horizon interpretation is a critical step in waveform classification. However, the horizon often produces inconsistent waveform phase, and thus results in an unsatisfied classification. To alleviate this problem, an adaptive phase waveform classification method called the adaptive phase k-means is introduced in this paper. Our method improves the traditional k-means algorithm using an adaptive phase distance for waveform similarity measure. The proposed distance is a measure with variable phases as it moves from sample to sample along the traces. Model traces are also updated with the best phase interference in the iterative process. Therefore, our method is robust to phase variations caused by the interpretation horizon. We tested the effectiveness of our algorithm by applying it to synthetic and real data. The satisfactory results reveal that the proposed method tolerates certain waveform phase variation and is a good tool for seismic facies analysis.

  17. Research methods for subgrouping low back pain

    DEFF Research Database (Denmark)

    Kent, Peter; Keating, Jennifer L; Leboeuf-Yde, Charlotte

    2010-01-01

    important distinctions in their treatment needs or prognoses. Due to a proliferation of research methods and variability in how subgrouping results are interpreted, it is timely to open discussion regarding a conceptual framework for the research designs and statistical methods available for subgrouping...... studies (a method framework). The aims of this debate article are: (1) to present a method framework to inform the design and evaluation of subgrouping research in low back pain, (2) to describe method options when investigating prognostic effects or subgroup treatment effects, and (3) to discuss...... the strengths and limitations of research methods suitable for the hypothesis-setting phase of subgroup studies....

  18. Qualitative Methods in Drug Utilization Research

    DEFF Research Database (Denmark)

    Almarsdóttir, Anna Birna; Bastholm Rahmner, Pia

    2016-01-01

    Qualitative research methods derive from the social sciences. Their use in drug utilization research is increasingly widespread, especially in understanding patient and prescriber perspectives. The main focus in qualitative research is exploration of a given phenomenon in order to get a wider...... understanding of why and how it appears. Qualitative research methods build on various theoretical underpinnings/schools of thought. The same validity and quality criteria cannot be used for both qualitative and quantitative methods....

  19. Lane marking detection based on waveform analysis and CNN

    Science.gov (United States)

    Ye, Yang Yang; Chen, Hou Jin; Hao, Xiao Li

    2017-06-01

    Lane markings detection is a very important part of the ADAS to avoid traffic accidents. In order to obtain accurate lane markings, in this work, a novel and efficient algorithm is proposed, which analyses the waveform generated from the road image after inverse perspective mapping (IPM). The algorithm includes two main stages: the first stage uses an image preprocessing including a CNN to reduce the background and enhance the lane markings. The second stage obtains the waveform of the road image and analyzes the waveform to get lanes. The contribution of this work is that we introduce local and global features of the waveform to detect the lane markings. The results indicate the proposed method is robust in detecting and fitting the lane markings.

  20. Methods in Lexicography and Dictionary Research | Schierholz ...

    African Journals Online (AJOL)

    Methods are used in every stage of dictionary-making and in every scientific analysis which is carried out in the field of dictionary research. This article presents some general considerations on methods in philosophy of science, gives an overview of many methods used in linguistics, in lexicography, dictionary research as ...

  1. The Delphi Method for Graduate Research

    Science.gov (United States)

    Skulmoski, Gregory J.; Hartman, Francis T.; Krahn, Jennifer

    2007-01-01

    The Delphi method is an attractive method for graduate students completing masters and PhD level research. It is a flexible research technique that has been successfully used in our program at the University of Calgary to explore new concepts within and outside of the information systems body of knowledge. The Delphi method is an iterative process…

  2. Faithful effective-one-body waveforms of small-mass-ratio coalescing black hole binaries

    International Nuclear Information System (INIS)

    Damour, Thibault; Nagar, Alessandro

    2007-01-01

    We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the effective-one-body (EOB) framework and propose a methodology for improving the current (waveform) implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform and on systematically comparing various EOB-based waveforms with exact waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio nonspinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include (i) a resummed, 3 PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the exact ones in modulus, frequency, and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within ±1.1% of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves

  3. Using Q Method in Qualitative Research

    Directory of Open Access Journals (Sweden)

    Pnina Shinebourne PhD

    2009-03-01

    Full Text Available In this paper the author outlines the features of Q method and assesses its suitability as a qualitative research method. She discusses the process of using the method and its particular approach to researching the range and diversity of subjective understandings, beliefs, and experiences. Q method is particularly suitable for identifying commonality and diversity and has a powerful capacity for thematic identification and analysis. In the author's view, Q method makes a contribution to expanding the repertoire of qualitative research methods.

  4. Time-domain simulation and waveform reconstruction for shielding effectiveness of materials against electromagnetic pulse

    International Nuclear Information System (INIS)

    Hu, Xiao-feng; Chen, Xiang; Wei, Ming

    2013-01-01

    Shielding effectiveness (SE) of materials of current testing standards is often carried out by using continuous-wave measurement and amplitude-frequency characteristics curve is used to characterize the results. However, with in-depth study of high-power electromagnetic pulse (EMP) interference, it was discovered that only by frequency-domain SE of materials cannot be completely characterized by shielding performance of time-domain pulsed-field. And there is no uniform testing methods and standards of SE of materials against EMP. In this paper, the method of minimum phase transfer function is used to reconstruct shielded time-domain waveform based on the analysis of the waveform reconstruction method. Pulse of plane waves through an infinite planar material is simulated by using CST simulation software. The reconstructed waveform and simulation waveform is compared. The results show that the waveform reconstruction method based on the minimum phase can be well estimated EMP waveform through the infinite planar materials.

  5. Integrating Research Skills Training into Non--Research Methods Courses

    Science.gov (United States)

    Woolf, Jules

    2014-01-01

    Research skills are a valued commodity by industry and university administrators. Despite the importance placed on these skills students typically dislike taking research method courses where these skills are learned. However, training in research skills does not necessarily have to be confined to these courses. In this study participants at a…

  6. [Internet research methods: advantages and challenges].

    Science.gov (United States)

    Liu, Yi; Tien, Yueh-Hsuan

    2009-12-01

    Compared to traditional research methods, using the Internet to conduct research offers a number of advantages to the researcher, which include increased access to sensitive issues and vulnerable / hidden populations; decreased data entry time requirements; and enhanced data accuracy. However, Internet research also presents certain challenges to the researcher. In this article, the advantages and challenges of Internet research methods are discussed in four principle issue areas: (a) recruitment, (b) data quality, (c) practicality, and (d) ethics. Nursing researchers can overcome problems related to sampling bias and data truthfulness using creative methods; resolve technical problems through collaboration with other disciplines; and protect participant's privacy, confidentiality and data security by maintaining a high level of vigilance. Once such issues have been satisfactorily addressed, the Internet should open a new window for Taiwan nursing research.

  7. Phase-space topography characterization of nonlinear ultrasound waveforms.

    Science.gov (United States)

    Dehghan-Niri, Ehsan; Al-Beer, Helem

    2018-03-01

    Fundamental understanding of ultrasound interaction with material discontinuities having closed interfaces has many engineering applications such as nondestructive evaluation of defects like kissing bonds and cracks in critical structural and mechanical components. In this paper, to analyze the acoustic field nonlinearities due to defects with closed interfaces, the use of a common technique in nonlinear physics, based on a phase-space topography construction of ultrasound waveform, is proposed. The central idea is to complement the "time" and "frequency" domain analyses with the "phase-space" domain analysis of nonlinear ultrasound waveforms. A nonlinear time series method known as pseudo phase-space topography construction is used to construct equivalent phase-space portrait of measured ultrasound waveforms. Several nonlinear models are considered to numerically simulate nonlinear ultrasound waveforms. The phase-space response of the simulated waveforms is shown to provide different topographic information, while the frequency domain shows similar spectral behavior. Thus, model classification can be substantially enhanced in the phase-space domain. Experimental results on high strength aluminum samples show that the phase-space transformation provides a unique detection and classification capabilities. The Poincaré map of the phase-space domain is also used to better understand the nonlinear behavior of ultrasound waveforms. It is shown that the analysis of ultrasound nonlinearities is more convenient and informative in the phase-space domain than in the frequency domain. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Adaptive Waveform Design for Cognitive Radar in Multiple Targets Situations

    Directory of Open Access Journals (Sweden)

    Xiaowen Zhang

    2018-02-01

    Full Text Available In this paper, the problem of cognitive radar (CR waveform optimization design for target detection and estimation in multiple extended targets situations is investigated. This problem is analyzed in signal-dependent interference, as well as additive channel noise for extended targets with unknown target impulse response (TIR. To address this problem, an improved algorithm is employed for target detection by maximizing the detection probability of the received echo on the promise of ensuring the TIR estimation precision. In this algorithm, an additional weight vector is introduced to achieve a trade-off among different targets. Both the estimate of TIR and transmit waveform can be updated at each step based on the previous step. Under the same constraint on waveform energy and bandwidth, the information theoretical approach is also considered. In addition, the relationship between the waveforms that are designed based on the two criteria is discussed. Unlike most existing works that only consider single target with temporally correlated characteristics, waveform design for multiple extended targets is considered in this method. Simulation results demonstrate that compared with linear frequency modulated (LFM signal, waveforms designed based on maximum detection probability and maximum mutual information (MI criteria can make radar echoes contain more multiple-target information and improve radar performance as a result.

  9. Optimal current waveforms for brushless permanent magnet motors

    Science.gov (United States)

    Moehle, Nicholas; Boyd, Stephen

    2015-07-01

    In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.

  10. 3D Electric Waveforms of Solar Wind Turbulence

    Science.gov (United States)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.

    2018-01-01

    Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individual waveforms using the three-dimensional antenna system of the SWaves experiments on the STEREO spacecraft. Samples are chosen using waveforms with an apparent periodic structure, selected visually. The short antennas of STEREO respond to density fluctuations and to electric fields. Measurement of four quantities using only three antennas presents a problem. Methods to overcome or to ignore this difficulty are presented. We attempt to decide whether the waveforms correspond to the whistler mode or the Alfvén mode by using the direction of rotation of the signal. Most of the waveforms are so oblique—nearly linearly polarized—that the direction cannot be determined. However, about one third of the waveforms can be identified, and whistlers and Alfvén waves are present in roughly equal numbers. The selected waveforms are very intense but intermittent and are orders of magnitude stronger than the average, yet their accumulated signal accounts for a large fraction of the average. The average, however, is supposed to be the result of a turbulent mixture of many waves, not short coherent events. This presents a puzzle for future work.

  11. Miscellaneous standard methods for Apis mellifera research

    DEFF Research Database (Denmark)

    Human, Hannelie; Brodschneider, Robert; Dietemann, Vincent

    2013-01-01

    A variety of methods are used in honey bee research and differ depending on the level at which the research is conducted. On an individual level, the handling of individual honey bees, including the queen, larvae and pupae are required. There are different methods for the immobilising, killing an...

  12. e-Learning Business Research Methods

    Science.gov (United States)

    Cowie, Jonathan

    2004-01-01

    This paper outlines the development of a generic Business Research Methods course from a simple name in a box to a full e-Learning web based module. It highlights particular issues surrounding the nature of the discipline and the integration of a large number of cross faculty subject specific research methods courses into a single generic module.…

  13. Optimizing How We Teach Research Methods

    Science.gov (United States)

    Cvancara, Kristen E.

    2017-01-01

    Courses: Research Methods (undergraduate or graduate level). Objective: The aim of this exercise is to optimize the ability for students to integrate an understanding of various methodologies across research paradigms within a 15-week semester, including a review of procedural steps and experiential learning activities to practice each method, a…

  14. Exploring methods in information literacy research

    CERN Document Server

    Lipu, Suzanne; Lloyd, Annemaree

    2007-01-01

    This book provides an overview of approaches to assist researchers and practitioners to explore ways of undertaking research in the information literacy field. The first chapter provides an introductory overview of research by Dr Kirsty Williamson (author of Research Methods for Students, Academics and Professionals: Information Management and Systems) and this sets the scene for the rest of the chapters where each author explores the key aspects of a specific method and explains how it may be applied in practice. The methods covered include those representing qualitative, quantitative and mix

  15. Qualitative versus quantitative methods in psychiatric research.

    Science.gov (United States)

    Razafsha, Mahdi; Behforuzi, Hura; Azari, Hassan; Zhang, Zhiqun; Wang, Kevin K; Kobeissy, Firas H; Gold, Mark S

    2012-01-01

    Qualitative studies are gaining their credibility after a period of being misinterpreted as "not being quantitative." Qualitative method is a broad umbrella term for research methodologies that describe and explain individuals' experiences, behaviors, interactions, and social contexts. In-depth interview, focus groups, and participant observation are among the qualitative methods of inquiry commonly used in psychiatry. Researchers measure the frequency of occurring events using quantitative methods; however, qualitative methods provide a broader understanding and a more thorough reasoning behind the event. Hence, it is considered to be of special importance in psychiatry. Besides hypothesis generation in earlier phases of the research, qualitative methods can be employed in questionnaire design, diagnostic criteria establishment, feasibility studies, as well as studies of attitude and beliefs. Animal models are another area that qualitative methods can be employed, especially when naturalistic observation of animal behavior is important. However, since qualitative results can be researcher's own view, they need to be statistically confirmed, quantitative methods. The tendency to combine both qualitative and quantitative methods as complementary methods has emerged over recent years. By applying both methods of research, scientists can take advantage of interpretative characteristics of qualitative methods as well as experimental dimensions of quantitative methods.

  16. Frequency-domain elastic full waveform inversion using encoded simultaneous sources

    Science.gov (United States)

    Jeong, W.; Son, W.; Pyun, S.; Min, D.

    2011-12-01

    Currently, numerous studies have endeavored to develop robust full waveform inversion and migration algorithms. These processes require enormous computational costs, because of the number of sources in the survey. To avoid this problem, the phase encoding technique for prestack migration was proposed by Romero (2000) and Krebs et al. (2009) proposed the encoded simultaneous-source inversion technique in the time domain. On the other hand, Ben-Hadj-Ali et al. (2011) demonstrated the robustness of the frequency-domain full waveform inversion with simultaneous sources for noisy data changing the source assembling. Although several studies on simultaneous-source inversion tried to estimate P- wave velocity based on the acoustic wave equation, seismic migration and waveform inversion based on the elastic wave equations are required to obtain more reliable subsurface information. In this study, we propose a 2-D frequency-domain elastic full waveform inversion technique using phase encoding methods. In our algorithm, the random phase encoding method is employed to calculate the gradients of the elastic parameters, source signature estimation and the diagonal entries of approximate Hessian matrix. The crosstalk for the estimated source signature and the diagonal entries of approximate Hessian matrix are suppressed with iteration as for the gradients. Our 2-D frequency-domain elastic waveform inversion algorithm is composed using the back-propagation technique and the conjugate-gradient method. Source signature is estimated using the full Newton method. We compare the simultaneous-source inversion with the conventional waveform inversion for synthetic data sets of the Marmousi-2 model. The inverted results obtained by simultaneous sources are comparable to those obtained by individual sources, and source signature is successfully estimated in simultaneous source technique. Comparing the inverted results using the pseudo Hessian matrix with previous inversion results

  17. Survey Research: Methods, Issues and the Future

    Science.gov (United States)

    Brewer, Ernest W.; Torrisi-Steele, Geraldine; Wang, Victor C. X.

    2015-01-01

    Survey research is prevalent among many professional fields. Both cost effective and time efficient, this method of research is commonly used for the purposes of gaining insight into the attitudes, thoughts, and opinions of populations. Additionally, because there are several types of survey research designs and data collection instruments, the…

  18. Future methods in pharmacy practice research

    DEFF Research Database (Denmark)

    Almarsdottir, A B; Babar, Z U D

    2016-01-01

    research. These are demographics, technology and professional standards. Second, deriving from this, it seeks to predict and forecast the future shifts in use of methodologies. Third, new research areas and availability of data impacting on future methods are discussed. These include the impact of aging...... of the trends for pharmacy practice research methods are discussed. © 2016, Springer International Publishing.......This article describes the current and future practice of pharmacy scenario underpinning and guiding this research and then suggests future directions and strategies for such research. First, it sets the scene by discussing the key drivers which could influence the change in pharmacy practice...

  19. Using observational methods in nursing research.

    Science.gov (United States)

    Salmon, Jenny

    2015-07-08

    Observation is a research data-collection method used generally to capture the activities of participants as well as when and where things are happening in a given setting. It checks description of the phenomena against what the researcher perceives to be fact in a rich experiential context. The method's main strength is that it provides direct access to the social phenomena under consideration. It can be used quantitatively or qualitatively, depending on the research question. Challenges in using observation relate to adopting the role of participant or non-participant researcher as observer. This article discusses some of the complexities involved when nurse researchers seek to collect observational data on social processes in naturalistic settings using unstructured or structured observational methods in qualitative research methodology. A glossary of research terms is provided.

  20. Research methods for English language teachers

    CERN Document Server

    McDonough, Jo

    2014-01-01

    This book offers a lively introduction to the research methods and techniques available to English language teachers who wish to investigate aspects of their own practice. It covers qualitative and quantitative methodology and includes sections on observation, introspection, diary studies, experiments, interviews, questionnaires, numerical techniques and case study research. Each method is illustrated with examples in language teaching contexts, and techniques of data collection and analysis are introduced. The authors focus particularly on research in the classroom, on tests, materials, the

  1. Elastic reflection waveform inversion with variable density

    KAUST Repository

    Li, Yuanyuan; Li, Zhenchun; Alkhalifah, Tariq Ali; Guo, Qiang

    2017-01-01

    Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion

  2. Hazard surveillance for workplace magnetic fields. 1: Walkaround sampling method for measuring ambient field magnitude; 2: Field characteristics from waveform measurements

    Energy Technology Data Exchange (ETDEWEB)

    Methner, M.M.; Bowman, J.D.

    1998-03-01

    Recent epidemiologic research has suggested that exposure to extremely low frequency (ELF) magnetic fields (MF) may be associated with leukemia, brain cancer, spontaneous abortions, and Alzheimer`s disease. A walkaround sampling method for measuring ambient ELF-MF levels was developed for use in conducting occupational hazard surveillance. This survey was designed to determine the range of MF levels at different industrial facilities so they could be categorized by MF levels and identified for possible subsequent personal exposure assessments. Industries were selected based on their annual electric power consumption in accordance with the hypothesis that large power consumers would have higher ambient MFs when compared with lower power consumers. Sixty-two facilities within thirteen 2-digit Standard Industrial Classifications (SIC) were selected based on their willingness to participate. A traditional industrial hygiene walkaround survey was conducted to identify MF sources, with a special emphasis on work stations.

  3. Design and implement of system for browsing remote seismic waveform based on B/S schema

    International Nuclear Information System (INIS)

    Zheng Xuefeng; Shen Junyi; Wang Zhihai; Sun Peng; Jin Ping; Yan Feng

    2006-01-01

    Browsing remote seismic waveform based on B/S schema is of significance in modern seismic research and data service, and the technology should be improved urgently. This paper describes the basic plan, architecture and implement of system for browsing remote seismic waveform based on B/S schema. The problem to access, browse and edit the waveform data on serve from client only using browser has been solved. On this basis, the system has been established and been in use. (authors)

  4. The Value of Mixed Methods Research: A Mixed Methods Study

    Science.gov (United States)

    McKim, Courtney A.

    2017-01-01

    The purpose of this explanatory mixed methods study was to examine the perceived value of mixed methods research for graduate students. The quantitative phase was an experiment examining the effect of a passage's methodology on students' perceived value. Results indicated students scored the mixed methods passage as more valuable than those who…

  5. Qualitative and quantitative methods in health research

    OpenAIRE

    V?zquez Navarrete, M. Luisa

    2009-01-01

    Introduction Research in the area of health has been traditionally dominated by quantitative research. However, the complexity of ill-health, which is socially constructed by individuals, health personnel and health authorities have motivated the search for other forms to approach knowledge. Aim To discuss the complementarities of qualitative and quantitative research methods in the generation of knowledge. Contents The purpose of quantitative research is to measure the magnitude of an event,...

  6. Waveform design for wireless power transfer

    OpenAIRE

    Clerckx, B; Bayguzina, E

    2016-01-01

    Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity ...

  7. Best waveform score for diagnosing keratoconus

    Directory of Open Access Journals (Sweden)

    Allan Luz

    2013-12-01

    Full Text Available PURPOSE: To test whether corneal hysteresis (CH and corneal resistance factor (CRF can discriminate between keratoconus and normal eyes and to evaluate whether the averages of two consecutive measurements perform differently from the one with the best waveform score (WS for diagnosing keratoconus. METHODS: ORA measurements for one eye per individual were selected randomly from 53 normal patients and from 27 patients with keratoconus. Two groups were considered the average (CH-Avg, CRF-Avg and best waveform score (CH-WS, CRF-WS groups. The Mann-Whitney U-test was used to evaluate whether the variables had similar distributions in the Normal and Keratoconus groups. Receiver operating characteristics (ROC curves were calculated for each parameter to assess the efficacy for diagnosing keratoconus and the same obtained for each variable were compared pairwise using the Hanley-McNeil test. RESULTS: The CH-Avg, CRF-Avg, CH-WS and CRF-WS differed significantly between the normal and keratoconus groups (p<0.001. The areas under the ROC curve (AUROC for CH-Avg, CRF-Avg, CH-WS, and CRF-WS were 0.824, 0.873, 0.891, and 0.931, respectively. CH-WS and CRF-WS had significantly better AUROCs than CH-Avg and CRF-Avg, respectively (p=0.001 and 0.002. CONCLUSION: The analysis of the biomechanical properties of the cornea through the ORA method has proved to be an important aid in the diagnosis of keratoconus, regardless of the method used. The best waveform score (WS measurements were superior to the average of consecutive ORA measurements for diagnosing keratoconus.

  8. Perceptually informed synthesis of bandlimited classical waveforms using integrated polynomial interpolation.

    Science.gov (United States)

    Välimäki, Vesa; Pekonen, Jussi; Nam, Juhan

    2012-01-01

    Digital subtractive synthesis is a popular music synthesis method, which requires oscillators that are aliasing-free in a perceptual sense. It is a research challenge to find computationally efficient waveform generation algorithms that produce similar-sounding signals to analog music synthesizers but which are free from audible aliasing. A technique for approximately bandlimited waveform generation is considered that is based on a polynomial correction function, which is defined as the difference of a non-bandlimited step function and a polynomial approximation of the ideal bandlimited step function. It is shown that the ideal bandlimited step function is equivalent to the sine integral, and that integrated polynomial interpolation methods can successfully approximate it. Integrated Lagrange interpolation and B-spline basis functions are considered for polynomial approximation. The polynomial correction function can be added onto samples around each discontinuity in a non-bandlimited waveform to suppress aliasing. Comparison against previously known methods shows that the proposed technique yields the best tradeoff between computational cost and sound quality. The superior method amongst those considered in this study is the integrated third-order B-spline correction function, which offers perceptually aliasing-free sawtooth emulation up to the fundamental frequency of 7.8 kHz at the sample rate of 44.1 kHz. © 2012 Acoustical Society of America.

  9. Using mixed methods when researching communities.

    Science.gov (United States)

    Ochieng, Bertha M N; Meetoo, Danny

    2015-09-01

    To argue for the use of mixed methods when researching communities. Although research involving minority communities is now advanced, not enough effort has been made to formulate methodological linkages between qualitative and quantitative methods in most studies. For instance, the quantitative approaches used by epidemiologists and others in examining the wellbeing of communities are usually empirical. While the rationale for this is sound, quantitative findings can be expanded with data from in-depth qualitative approaches, such as interviews or observations, which are likely to provide insights into the experiences of people in those communities and their relationships with their wellbeing. Academic databases including The Cochrane Library, MEDLINE, CINAHL, AMED, INTERNURSE, Science Direct, Web of Knowledge and PubMed. An iterative process of identifying eligible literature was carried out by comprehensively searching electronic databases. Using mixed-methods approaches is likely to address any potential drawbacks of individual methods by exploiting the strengths of each at the various stages of research. Combining methods can provide additional ways of looking at a complex problem and improve the understanding of a community's experiences. However, it is important for researchers to use the different methods interactively during their research. The use of qualitative and quantitative methods is likely to enrich our understanding of the interrelationship between wellbeing and the experiences of communities. This should help researchers to explore socio-cultural factors and experiences of health and healthcare practice more effectively.

  10. Sinusoidal oscillators and waveform generators using modern electronic circuit building blocks

    CERN Document Server

    Senani, Raj; Singh, V K; Sharma, R K

    2016-01-01

    This book serves as a single-source reference to sinusoidal oscillators and waveform generators, using classical as well as a variety of modern electronic circuit building blocks. It provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators and includes a catalogue of over 600 configurations of oscillators and waveform generators, describing their relevant design details and salient performance features/limitations. The authors discuss a number of interesting, open research problems and include a comprehensive collection of over 1500 references on oscillators and non-sinusoidal waveform generators/relaxation oscillators. Offers readers a single-source reference to everything connected to sinusoidal oscillators and waveform generators, using classical as well as modern electronic circuit building blocks; Provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators; Includes a catalog of over 600 configurations of oscillato...

  11. Research Methods in European Union Studies

    DEFF Research Database (Denmark)

    Lynggaard, Kennet; Manners, Ian; Löfgren, Karl

    Research on the European Union over the past few years has been strongly implicated in the crises that currently grip Europe with a failure to ask the pertinent questions as well as a perceived weakness in the methods and evidence used by researchers providing the basis for these allegations....... This volume moves the study of EU research strategies beyond the dichotomies of the past towards a new agenda for research on Europe through a rich diversity of problem-solving based research. This new agenda acknowledges the weaknesses of the past and moves beyond them towards greater openness and awareness...

  12. Phenomenological Research Method, Design and Procedure: A ...

    African Journals Online (AJOL)

    Phenomenological Research Method, Design and Procedure: A Phenomenological Investigation of the Phenomenon of Being-in-Community as Experienced by Two Individuals Who Have Participated in a Community Building Workshop.

  13. Food studies: an introduction to research methods

    National Research Council Canada - National Science Library

    Miller, Jeff; Deutsch, Jonathan

    2009-01-01

    .... Designed for the classroom as well as for the independent scholar, the book details the predominant research methods in the field, provides a series of interactive questions and templates to help...

  14. Complex Crustal Structure Beneath Western Turkey Revealed by 3D Seismic Full Waveform Inversion (FWI)

    Science.gov (United States)

    Cubuk-Sabuncu, Yesim; Taymaz, Tuncay; Fichtner, Andreas

    2016-04-01

    We present a 3D radially anisotropic velocity model of the crust and uppermost mantle structure beneath the Sea of Marmara and surroundings based on the full waveform inversion method. The intense seismic activity and crustal deformation are observed in the Northwest Turkey due to transition tectonics between the strike-slip North Anatolian Fault (NAF) and the extensional Aegean region. We have selected and simulated complete waveforms of 62 earthquakes (Mw > 4.0) occurred during 2007-2015, and recorded at (Δ Technological Research Council of Turkey (TUBITAK Project No: ÇAYDAG-114Y066), and EU-HORIZON-2020: COST Actions: Earth System Science and Environmental Management: ES1401 - Time Dependent Seismology (TIDES).

  15. Mixed Methods Research Designs in Counseling Psychology

    Science.gov (United States)

    Hanson, William E.; Creswell, John W.; Clark, Vicki L. Plano; Petska, Kelly S.; Creswell, David J.

    2005-01-01

    With the increased popularity of qualitative research, researchers in counseling psychology are expanding their methodologies to include mixed methods designs. These designs involve the collection, analysis, and integration of quantitative and qualitative data in a single or multiphase study. This article presents an overview of mixed methods…

  16. The Delphi Method in Rehabilitation Counseling Research

    Science.gov (United States)

    Vazquez-Ramos, Robinson; Leahy, Michael; Estrada Hernandez, Noel

    2007-01-01

    Rehabilitation researchers have found in the application of the Delphi method a more sophisticated way of obtaining consensus from experts in the field on certain matters. The application of this research methodology has affected and certainly advanced the body of knowledge of the rehabilitation counseling practice. However, the rehabilitation…

  17. Qualitative research methods for medical educators.

    Science.gov (United States)

    Hanson, Janice L; Balmer, Dorene F; Giardino, Angelo P

    2011-01-01

    This paper provides a primer for qualitative research in medical education. Our aim is to equip readers with a basic understanding of qualitative research and prepare them to judge the goodness of fit between qualitative research and their own research questions. We provide an overview of the reasons for choosing a qualitative research approach and potential benefits of using these methods for systematic investigation. We discuss developing qualitative research questions, grounding research in a philosophical framework, and applying rigorous methods of data collection, sampling, and analysis. We also address methods to establish the trustworthiness of a qualitative study and introduce the reader to ethical concerns that warrant special attention when planning qualitative research. We conclude with a worksheet that readers may use for designing a qualitative study. Medical educators ask many questions that carefully designed qualitative research would address effectively. Careful attention to the design of qualitative studies will help to ensure credible answers that will illuminate many of the issues, challenges, and quandaries that arise while doing the work of medical education. Copyright © 2011 Academic Pediatric Association. All rights reserved.

  18. Mapping Mixed Methods Research: Methods, Measures, and Meaning

    Science.gov (United States)

    Wheeldon, J.

    2010-01-01

    This article explores how concept maps and mind maps can be used as data collection tools in mixed methods research to combine the clarity of quantitative counts with the nuance of qualitative reflections. Based on more traditional mixed methods approaches, this article details how the use of pre/post concept maps can be used to design qualitative…

  19. Students' perspectives of undergraduate research methods ...

    African Journals Online (AJOL)

    Introduction: in this study we used a model of adult learning to explore undergraduate students' views on how to improve the teaching of research methods and biostatistics. Methods: this was a secondary analysis of survey data of 600 undergraduate students from three medical schools in Uganda. The analysis looked at ...

  20. Using Replication Projects in Teaching Research Methods

    Science.gov (United States)

    Standing, Lionel G.; Grenier, Manuel; Lane, Erica A.; Roberts, Meigan S.; Sykes, Sarah J.

    2014-01-01

    It is suggested that replication projects may be valuable in teaching research methods, and also address the current need in psychology for more independent verification of published studies. Their use in an undergraduate methods course is described, involving student teams who performed direct replications of four well-known experiments, yielding…

  1. Social Experiments and Participatory Research as Method

    DEFF Research Database (Denmark)

    Dirckinck-Holmfeld, Lone

    2007-01-01

    Interdisciplinary research with stakeholders and users challenge the research methodologies to be used. These have to provide a shared language for all the participants, to build up trust, and to offer insights into the diverse perspectives of the participants. Further more it challenge ways to d...... practice-based methods where "social experiments with technology" and "dialogue research" are the key-words. ...... to discuss and validate contributions from each others - across different criteria for each discipline, and crosswise different agendas for stakeholders, politicians, practitioners and researchers. Participatory research and social experiments are methodologies which have been developed to cope......Interdisciplinary research with stakeholders and users challenge the research methodologies to be used. These have to provide a shared language for all the participants, to build up trust, and to offer insights into the diverse perspectives of the participants. Further more it challenge ways...

  2. Closed-loop waveform control of boost inverter

    DEFF Research Database (Denmark)

    Zhu, Guo Rong; Xiao, Cheng Yuan; Wang, Haoran

    2016-01-01

    The input current of single-phase inverter typically has an AC ripple component at twice the output frequency, which causes a reduction in both the operating lifetime of its DC source and the efficiency of the system. In this paper, the closed-loop performance of a proposed waveform control method...... to eliminate such a ripple current in boost inverter is investigated. The small-signal stability and the dynamic characteristic of the inverter system for input voltage or wide range load variations under the closed-loop waveform control method are studied. It is validated that with the closedloop waveform...... control, not only was stability achieved, the reference voltage of the boost inverter capacitors can be instantaneously adjusted to match the new load, thereby achieving improved ripple mitigation for a wide load range. Furthermore, with the control and feedback mechanism, there is minimal level of ripple...

  3. Analysis of Gradient Waveform in Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    OU-YANG Shan-mei

    2017-12-01

    Full Text Available The accuracy of gradient pulse waveform affects image quality significantly in magnetic resonance imaging (MRI. Recording and analyzing the waveform of gradient pulse helps to make rapid and accurate diagnosis of spectrometer gradient hardware and/or pulse sequence. Using the virtual instrument software LabVIEW to control the high speed data acquisition card DAQ-2005, a multi-channel acquisition scheme was designed to collect the gradient outputs from a custom-made spectrometer. The collected waveforms were post-processed (i.e., histogram statistical analysis, data filtering and difference calculation to obtain feature points containing time and amplitude information. Experiments were carried out to validate the method, which is an auxiliary test method for the development of spectrometer and pulses sequence.

  4. Qualitative methods in pharmacy practice research

    DEFF Research Database (Denmark)

    Kaae, Susanne; Traulsen, Janine Marie

    2015-01-01

    Qualitative research within pharmacy practice is concerned with understanding the behavior of actors such as pharmacy staff, pharmacy owners, patients, other healthcare professionals, and politicians to explore various types of existing practices and beliefs in order to improve them. As qualitative...... research attempts to answer the “why” questions, it is useful for describing, in rich detail, complex phenomena that are situated and embedded in local contexts. Typical methods include interviews, observation, document analysis, and netnography. Qualitative research has to live up to a set of rigid...... quality criteria of research conduct to provide trustworthy results that contribute to the further development of the area....

  5. Experimental validation of waveform relaxation technique for power ...

    Indian Academy of Sciences (India)

    damping controller drawn our attention to a potential convergence problem which ... method was originally proposed as a method of parallelizing the numerical integration of very. Figure 2 ..... to it the features of an industrial real-time operating system. ..... Odeh F and Ruehli A 1985 Waveform relaxation: Theory and practice.

  6. Elastic reflection waveform inversion with variable density

    KAUST Repository

    Li, Yuanyuan

    2017-08-17

    Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion (RWI) provides a method to build a good background model, which can serve as an initial model for elastic FWI. Therefore, we introduce the concept of RWI for elastic media, and propose elastic RWI with variable density. We apply Born modeling to generate the synthetic reflection data by using optimized perturbations of P- and S-wave velocities and density. The inversion for the perturbations in P- and S-wave velocities and density is similar to elastic least-squares reverse time migration (LSRTM). An incorrect initial model will lead to some misfits at the far offsets of reflections; thus, can be utilized to update the background velocity. We optimize the perturbation and background models in a nested approach. Numerical tests on the Marmousi model demonstrate that our method is able to build reasonably good background models for elastic FWI with absence of low frequencies, and it can deal with the variable density, which is needed in real cases.

  7. Research on atmospheric transmission distortion of Gauss laser using multiple phase screen method

    Science.gov (United States)

    Zhang, Yizhuo; Wang, Qiushi; Gu, Haidong

    2018-02-01

    The laser beam is attenuated, broadened, defocused and may even be deflected from its initial propagation direction as it propagates through the atmosphere. It leads to the decrease of the laser intensity of the receiving surface. Gauss beam is the fundamental components of all possible laser waveforms. Therefore, research on the transmission of the Gauss laser has far-reaching consequences in optical communication, weaponry, target designation, ranging, remote sensing and other applications that require transmission of laser beams through the atmosphere. In this paper, we propose a laboratory simulation method using multi-phase screen to calculate the effects of atmospheric turbulence. Theoretical analysis of Gauss laser transmission in the atmosphere is given. By calculating the propagation of the Gauss beam TEM00, the far field intensity and phase distribution is shown. By the given method, the optical setup is presented and used for optimizing the adaptive optics algorithm.

  8. Using ethnographic methods in software engineering research

    DEFF Research Database (Denmark)

    Sharp, Helen, C.; Dittrich, Yvonne; De Souza, Cleidson

    2010-01-01

    This tutorial provides an overview of the role of ethnography in Software Engineering research. It describes the use of ethnographic methods as a means to provide an in-depth understanding of the socio-technological realities surrounding everyday software development practice. The knowledge gained......-depth discussion of methods for data collection and analysis used in ethnographic studies. It then describes how these methods can be and have been used by software engineering researchers to understand developers' work practices, to inform the development of processes, methods and tools and to evaluate...... can be used to improve processes, methods and tools as well as develop observed industrial practices. The tutorial begins with a brief historical account of ethnography in the fields of Software Engineering, CSCW, Information Systems and other related areas. This sets the stage for a more in...

  9. WaveformECG: A Platform for Visualizing, Annotating, and Analyzing ECG Data.

    Science.gov (United States)

    Winslow, Raimond L; Granite, Stephen; Jurado, Christian

    2016-01-01

    The electrocardiogram (ECG) is the most commonly collected data in cardiovascular research because of the ease with which it can be measured and because changes in ECG waveforms reflect underlying aspects of heart disease. Accessed through a browser, WaveformECG is an open source platform supporting interactive analysis, visualization, and annotation of ECGs.

  10. Classification of Pulse Waveforms Using Edit Distance with Real Penalty

    Directory of Open Access Journals (Sweden)

    Zhang Dongyu

    2010-01-01

    Full Text Available Abstract Advances in sensor and signal processing techniques have provided effective tools for quantitative research in traditional Chinese pulse diagnosis (TCPD. Because of the inevitable intraclass variation of pulse patterns, the automatic classification of pulse waveforms has remained a difficult problem. In this paper, by referring to the edit distance with real penalty (ERP and the recent progress in -nearest neighbors (KNN classifiers, we propose two novel ERP-based KNN classifiers. Taking advantage of the metric property of ERP, we first develop an ERP-induced inner product and a Gaussian ERP kernel, then embed them into difference-weighted KNN classifiers, and finally develop two novel classifiers for pulse waveform classification. The experimental results show that the proposed classifiers are effective for accurate classification of pulse waveform.

  11. Research Methods in Healthcare Epidemiology: Survey and Qualitative Research.

    Science.gov (United States)

    Safdar, Nasia; Abbo, Lilian M; Knobloch, Mary Jo; Seo, Susan K

    2016-11-01

    Surveys are one of the most frequently employed study designs in healthcare epidemiology research. Generally easier to undertake and less costly than many other study designs, surveys can be invaluable to gain insights into opinions and practices in large samples and may be descriptive and/or be used to test associations. In this context, qualitative research methods may complement this study design either at the survey development phase and/or at the interpretation/extension of results stage. This methods article focuses on key considerations for designing and deploying surveys in healthcare epidemiology and antibiotic stewardship, including identification of whether or not de novo survey development is necessary, ways to optimally lay out and display a survey, denominator measurement, discussion of biases to keep in mind particularly in research using surveys, and the role of qualitative research methods to complement surveys. We review examples of surveys in healthcare epidemiology and antimicrobial stewardship and review the pros and cons of methods used. A checklist is provided to help aid design and deployment of surveys in healthcare epidemiology and antimicrobial stewardship. Infect Control Hosp Epidemiol 2016;1-6.

  12. Is Mixed Methods Research Used in Australian Career Development Research?

    Science.gov (United States)

    Cameron, Roslyn

    2010-01-01

    Mixed methods research has become a substantive and growing methodological force that is growing in popularity within the human and social sciences. This article reports the findings of a study that has systematically reviewed articles from the "Australian Journal of Career Development" from 2004 to 2009. The aim of the study was to…

  13. Computational Stimulation of the Basal Ganglia Neurons with Cost Effective Delayed Gaussian Waveforms.

    Science.gov (United States)

    Daneshzand, Mohammad; Faezipour, Miad; Barkana, Buket D

    2017-01-01

    Deep brain stimulation (DBS) has compelling results in the desynchronization of the basal ganglia neuronal activities and thus, is used in treating the motor symptoms of Parkinson's disease (PD). Accurate definition of DBS waveform parameters could avert tissue or electrode damage, increase the neuronal activity and reduce energy cost which will prolong the battery life, hence avoiding device replacement surgeries. This study considers the use of a charge balanced Gaussian waveform pattern as a method to disrupt the firing patterns of neuronal cell activity. A computational model was created to simulate ganglia cells and their interactions with thalamic neurons. From the model, we investigated the effects of modified DBS pulse shapes and proposed a delay period between the cathodic and anodic parts of the charge balanced Gaussian waveform to desynchronize the firing patterns of the GPe and GPi cells. The results of the proposed Gaussian waveform with delay outperformed that of rectangular DBS waveforms used in in-vivo experiments. The Gaussian Delay Gaussian (GDG) waveforms achieved lower number of misses in eliciting action potential while having a lower amplitude and shorter length of delay compared to numerous different pulse shapes. The amount of energy consumed in the basal ganglia network due to GDG waveforms was dropped by 22% in comparison with charge balanced Gaussian waveforms without any delay between the cathodic and anodic parts and was also 60% lower than a rectangular charged balanced pulse with a delay between the cathodic and anodic parts of the waveform. Furthermore, by defining a Synchronization Level metric, we observed that the GDG waveform was able to reduce the synchronization of GPi neurons more effectively than any other waveform. The promising results of GDG waveforms in terms of eliciting action potential, desynchronization of the basal ganglia neurons and reduction of energy consumption can potentially enhance the performance of DBS

  14. Computational Stimulation of the Basal Ganglia Neurons with Cost Effective Delayed Gaussian Waveforms

    Directory of Open Access Journals (Sweden)

    Mohammad Daneshzand

    2017-08-01

    Full Text Available Deep brain stimulation (DBS has compelling results in the desynchronization of the basal ganglia neuronal activities and thus, is used in treating the motor symptoms of Parkinson's disease (PD. Accurate definition of DBS waveform parameters could avert tissue or electrode damage, increase the neuronal activity and reduce energy cost which will prolong the battery life, hence avoiding device replacement surgeries. This study considers the use of a charge balanced Gaussian waveform pattern as a method to disrupt the firing patterns of neuronal cell activity. A computational model was created to simulate ganglia cells and their interactions with thalamic neurons. From the model, we investigated the effects of modified DBS pulse shapes and proposed a delay period between the cathodic and anodic parts of the charge balanced Gaussian waveform to desynchronize the firing patterns of the GPe and GPi cells. The results of the proposed Gaussian waveform with delay outperformed that of rectangular DBS waveforms used in in-vivo experiments. The Gaussian Delay Gaussian (GDG waveforms achieved lower number of misses in eliciting action potential while having a lower amplitude and shorter length of delay compared to numerous different pulse shapes. The amount of energy consumed in the basal ganglia network due to GDG waveforms was dropped by 22% in comparison with charge balanced Gaussian waveforms without any delay between the cathodic and anodic parts and was also 60% lower than a rectangular charged balanced pulse with a delay between the cathodic and anodic parts of the waveform. Furthermore, by defining a Synchronization Level metric, we observed that the GDG waveform was able to reduce the synchronization of GPi neurons more effectively than any other waveform. The promising results of GDG waveforms in terms of eliciting action potential, desynchronization of the basal ganglia neurons and reduction of energy consumption can potentially enhance the

  15. Qualitative Methods in Mental Health Services Research

    Science.gov (United States)

    Palinkas, Lawrence A.

    2014-01-01

    Qualitative and mixed methods play a prominent role in mental health services research. However, the standards for their use are not always evident, especially for those not trained in such methods. This paper reviews the rationale and common approaches to using qualitative and mixed methods in mental health services and implementation research based on a review of the papers included in this special series along with representative examples from the literature. Qualitative methods are used to provide a “thick description” or depth of understanding to complement breadth of understanding afforded by quantitative methods, elicit the perspective of those being studied, explore issues that have not been well studied, develop conceptual theories or test hypotheses, or evaluate the process of a phenomenon or intervention. Qualitative methods adhere to many of the same principles of scientific rigor as quantitative methods, but often differ with respect to study design, data collection and data analysis strategies. For instance, participants for qualitative studies are usually sampled purposefully rather than at random and the design usually reflects an iterative process alternating between data collection and analysis. The most common techniques for data collection are individual semi-structured interviews, focus groups, document reviews, and participant observation. Strategies for analysis are usually inductive, based on principles of grounded theory or phenomenology. Qualitative methods are also used in combination with quantitative methods in mixed method designs for convergence, complementarity, expansion, development, and sampling. Rigorously applied qualitative methods offer great potential in contributing to the scientific foundation of mental health services research. PMID:25350675

  16. Qualitative and Mixed Methods Social Media Research

    OpenAIRE

    Chareen L. Snelson

    2016-01-01

    Social media technologies have attracted substantial attention among many types of users including researchers who have published studies for several years. This article presents an overview of trends in qualitative and mixed methods social media research literature published from 2007 through 2013. A collection of 229 qualitative studies were identified through a systematic literature review process. A subset of 55 of these articles report studies involving a combination of qualitative and q...

  17. Improving waveform inversion using modified interferometric imaging condition

    Science.gov (United States)

    Guo, Xuebao; Liu, Hong; Shi, Ying; Wang, Weihong; Zhang, Zhen

    2018-02-01

    Similar to the reverse-time migration, full waveform inversion in the time domain is a memory-intensive processing method. The computational storage size for waveform inversion mainly depends on the model size and time recording length. In general, 3D and 4D data volumes need to be saved for 2D and 3D waveform inversion gradient calculations, respectively. Even the boundary region wavefield-saving strategy creates a huge storage demand. Using the last two slices of the wavefield to reconstruct wavefields at other moments through the random boundary, avoids the need to store a large number of wavefields; however, traditional random boundary method is less effective at low frequencies. In this study, we follow a new random boundary designed to regenerate random velocity anomalies in the boundary region for each shot of each iteration. The results obtained using the random boundary condition in less illuminated areas are more seriously affected by random scattering than other areas due to the lack of coverage. In this paper, we have replaced direct correlation for computing the waveform inversion gradient by modified interferometric imaging, which enhances the continuity of the imaging path and reduces noise interference. The new imaging condition is a weighted average of extended imaging gathers can be directly used in the gradient computation. In this process, we have not changed the objective function, and the role of the imaging condition is similar to regularization. The window size for the modified interferometric imaging condition-based waveform inversion plays an important role in this process. The numerical examples show that the proposed method significantly enhances waveform inversion performance.

  18. Qualitative and Mixed Methods Social Media Research

    Directory of Open Access Journals (Sweden)

    Chareen L. Snelson

    2016-02-01

    Full Text Available Social media technologies have attracted substantial attention among many types of users including researchers who have published studies for several years. This article presents an overview of trends in qualitative and mixed methods social media research literature published from 2007 through 2013. A collection of 229 qualitative studies were identified through a systematic literature review process. A subset of 55 of these articles report studies involving a combination of qualitative and quantitative methods. Articles were reviewed, analyzed, and coded through a qualitative content analysis approach. Overall trends are presented with respect to the entire collection of articles followed by an analysis of mixed methods research approaches identified in the subset of 55 studies. The most commonly used research approaches involved collecting data from people through interview, focus group, and survey methodologies. Content analysis was the second most commonly used approach whereby researchers use Facebook posts, Tweets (Twitter posts, YouTube videos, or other social media content as a data source. Many of the studies involving combinations of quantitative and qualitative data followed a design resembling Creswell and Plano Clark’s basic mixed methods typology (e.g., convergent parallel, explanatory sequential, and exploratory sequential.

  19. Mixed Methods Designs for Sports Medicine Research.

    Science.gov (United States)

    Kay, Melissa C; Kucera, Kristen L

    2018-07-01

    Mixed methods research is a relatively new approach in the field of sports medicine, where the benefits of qualitative and quantitative research are combined while offsetting the other's flaws. Despite its known and successful use in other populations, it has been used minimally in sports medicine, including studies of the clinician perspective, concussion, and patient outcomes. Therefore, there is a need for this approach to be applied in other topic areas not easily addressed by one type of research approach in isolation, such as the retirement from sport, effects of and return from injury, and catastrophic injury. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Phenomenography: A Missed Method in Medical Research

    Directory of Open Access Journals (Sweden)

    Assarroudi Abdolghader

    2016-09-01

    Full Text Available Research is an approach with which human beings can attempt to answer questions and discover the unknowns. Research methodology is something that is determined by the researcher’s attitude toward the universe as well as by the question he is trying to answer. Some essential questions regarding the research process are: “What is the nature of reality?”, “What is the nature of the relationship between the scholar and the subject of interest?”, and “How can one understand the subject, and what are the methods?”. Research approaches can be categorized as quantitative and qualitative. In the former, measurement, prediction, and control are the bases, while in the latter, exploring, describing, and explaining the phenomena are fundamental. Among qualitative research methods, phenomenography is one of the newest methods. However, in spite of proving to be useful in various disciplines, it has yet to become popular, and many scholars mistake it for phenomenology. The focus of phenomenography is on what is known as the second-order perspective and the different ways that people can experience the same phenomenon, while phenomenology primarily emphasizes the first-order perspective and the similar essences that are derived from various experiences. This article aims to provide a better understanding of phenomenography through explaining it and comparing it with phenomenology in order to facilitate its proper and timely application in medical studies.

  1. Reliability and risk analysis methods research plan

    International Nuclear Information System (INIS)

    1984-10-01

    This document presents a plan for reliability and risk analysis methods research to be performed mainly by the Reactor Risk Branch (RRB), Division of Risk Analysis and Operations (DRAO), Office of Nuclear Regulatory Research. It includes those activities of other DRAO branches which are very closely related to those of the RRB. Related or interfacing programs of other divisions, offices and organizations are merely indicated. The primary use of this document is envisioned as an NRC working document, covering about a 3-year period, to foster better coordination in reliability and risk analysis methods development between the offices of Nuclear Regulatory Research and Nuclear Reactor Regulation. It will also serve as an information source for contractors and others to more clearly understand the objectives, needs, programmatic activities and interfaces together with the overall logical structure of the program

  2. PBX-M waveform generator

    International Nuclear Information System (INIS)

    Feng, H.; Frank, K.T.; Kaye, S.

    1987-01-01

    The PBX-M (Princeton Beta Experiment) is an unique Tokamak experiment designed to run with a highly indented plasma. The shaping control will be accomplished through a closed-loop power supply control system. The system will make use of sixteen pre-programmed reference signals and twenty signals taken from direct measurements as input to an analog computer. Through a matrix conversion in the analog computer, these input signals will be used to generate eight control signals to control the eight power supplies. The pre-programmed reference signals will be created using a Macintosh personal computer interfaced to CAMAC (Comptuer Automated Measurement And Control) hardware for down-loading waveforms. The reference signals will be created on the Macintosh by the physics operators, utilizing the full graphics capability of the system. These waveforms are transferred to CAMAC memory, which are then strobed in real time through digital-to-analog converters and fed into the analog computer. The overall system (both hardware and software) is designed to be fail-safe. Specific features of the system, such as load inhibit and discharge inhibit, are discussed

  3. Mixed methods research: a design for emergency care research?

    Science.gov (United States)

    Cooper, Simon; Porter, Jo; Endacott, Ruth

    2011-08-01

    This paper follows previous publications on generic qualitative approaches, qualitative designs and action research in emergency care by this group of authors. Contemporary views on mixed methods approaches are considered, with a particular focus on the design choice and the amalgamation of qualitative and quantitative data emphasising the timing of data collection for each approach, their relative 'weight' and how they will be mixed. Mixed methods studies in emergency care are reviewed before the variety of methodological approaches and best practice considerations are presented. The use of mixed methods in clinical studies is increasing, aiming to answer questions such as 'how many' and 'why' in the same study, and as such are an important and useful approach to many key questions in emergency care.

  4. Microseismic event location by master-event waveform stacking

    Science.gov (United States)

    Grigoli, F.; Cesca, S.; Dahm, T.

    2016-12-01

    Waveform stacking location methods are nowadays extensively used to monitor induced seismicity monitoring assoiciated with several underground industrial activities such as Mining, Oil&Gas production and Geothermal energy exploitation. In the last decade a significant effort has been spent to develop or improve methodologies able to perform automated seismological analysis for weak events at a local scale. This effort was accompanied by the improvement of monitoring systems, resulting in an increasing number of large microseismicity catalogs. The analysis of microseismicity is challenging, because of the large number of recorded events often characterized by a low signal-to-noise ratio. A significant limitation of the traditional location approaches is that automated picking is often done on each seismogram individually, making little or no use of the coherency information between stations. In order to improve the performance of the traditional location methods, in the last year, alternative approaches have been proposed. These methods exploits the coherence of the waveforms recorded at different stations and do not require any automated picking procedure. The main advantage of this methods relies on their robustness even when the recorded waveforms are very noisy. On the other hand, like any other location method, the location performance strongly depends on the accuracy of the available velocity model. When dealing with inaccurate velocity models, in fact, location results can be affected by large errors. Here we will introduce a new automated waveform stacking location method which is less dependent on the knowledge of the velocity model and presents several benefits, which improve the location accuracy: 1) it accounts for phase delays due to local site effects, e.g. surface topography or variable sediment thickness 2) theoretical velocity model are only used to estimate travel times within the source volume, and not along the whole source-sensor path. We

  5. Creative Research Methods - a reflective online discussion

    Directory of Open Access Journals (Sweden)

    Ruth Leary

    2014-03-01

    Full Text Available In November 2013, the Institute of Advanced Studies (University of Warwick hosted a meeting of interdisciplinary colleagues interested in Creative Research Methods. The aspirations were to kick-start the debate at Warwick and create a platform from which researchers can develop projects that embrace new forms of intellectual enquiry and knowledge production. Following the meeting, several of the attendees agreed to develop some of the discussion points and briefly responded to a number of questions in an online document over a period of a few weeks. This paper is the result of that real space and online collaboration.

  6. Participatory design methods in telemedicine research

    DEFF Research Database (Denmark)

    Danbjørg, Dorthe Boe; Clemensen, Jane; Rothmann, Mette Juel

    together with the patients. Participatory design is a research design and methodology that encourages the participation of users in the design process of technological solutions. Therefore, it has a potential for designing technologies that actually reflect the needs of the users, why it is relevant within...... telemedicine. The aim of this presentation is to explain the process and theoretical framework of a PD project; give an example of a project including the applied methods, and to determine its application to telemedicine with focus on the rationale for genuine participation. Theory: Participation implies....... Methods: Key activities of a Participatory Design project comprise methods such as fieldwork; literature reviewing; development and testing, and user activities as workshops. Methods that support telling, making, enacting. For instance telling activities as drivers for participation, where practitioners...

  7. Auto-correlation based intelligent technique for complex waveform presentation and measurement

    International Nuclear Information System (INIS)

    Rana, K P S; Singh, R; Sayann, K S

    2009-01-01

    Waveform acquisition and presentation forms the heart of many measurement systems. Particularly, data acquisition and presentation of repeating complex signals like sine sweep and frequency-modulated signals introduces the challenge of waveform time period estimation and live waveform presentation. This paper presents an intelligent technique, for waveform period estimation of both the complex and simple waveforms, based on the normalized auto-correlation method. The proposed technique is demonstrated using LabVIEW based intensive simulations on several simple and complex waveforms. Implementation of the technique is successfully demonstrated using LabVIEW based virtual instrumentation. Sine sweep vibration waveforms are successfully presented and measured for electrodynamic shaker system generated vibrations. The proposed method is also suitable for digital storage oscilloscope (DSO) triggering, for complex signals acquisition and presentation. This intelligence can be embodied into the DSO, making it an intelligent measurement system, catering wide varieties of the waveforms. The proposed technique, simulation results, robustness study and implementation results are presented in this paper.

  8. Statistical methods in personality assessment research.

    Science.gov (United States)

    Schinka, J A; LaLone, L; Broeckel, J A

    1997-06-01

    Emerging models of personality structure and advances in the measurement of personality and psychopathology suggest that research in personality and personality assessment has entered a stage of advanced development, in this article we examine whether researchers in these areas have taken advantage of new and evolving statistical procedures. We conducted a review of articles published in the Journal of Personality, Assessment during the past 5 years. Of the 449 articles that included some form of data analysis, 12.7% used only descriptive statistics, most employed only univariate statistics, and fewer than 10% used multivariate methods of data analysis. We discuss the cost of using limited statistical methods, the possible reasons for the apparent reluctance to employ advanced statistical procedures, and potential solutions to this technical shortcoming.

  9. Experimental methods of shock wave research

    CERN Document Server

    Seiler, Friedrich

    2016-01-01

    This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.

  10. Hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver

    International Nuclear Information System (INIS)

    Oguzkurt, Levent; Yildirim, Tulin; Torun, Dilek; Tercan, Fahri; Kizilkilic, Osman; Niron, E. Alp

    2005-01-01

    Objective: To determine the incidence of abnormal hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver (FIL). Materials and methods: In this prospective study, 40 patients with diffuse FIL and 50 normal healthy adults who served as control group underwent hepatic vein (HV) Doppler ultrasonography. The patients with the diagnosis of FIL were 23 men (57.5%) and 17 women aged 30-62 years (mean age ± S.D., 42 ± 12 years). Subjects in the control group were 27 men (54%) and 23 women aged 34-65 years (mean age ± S.D., 45 ± 14 years). The diagnosis of FIL was confirmed with computed tomography density measurements. The waveforms of HV were classified into three groups: regular triphasic waveform, biphasic waveform without a reverse flow, and monophasic or flat waveform. Etiological factors for FIL were diabetes mellitus (DM), hyperlipidemia and obesity (body mass index > 25). Serum lipid profile was obtained from all the patients with FIL. Results: Seventeen of the 40 patients (43%) with FIL had an abnormal HV Doppler waveform, whereas only one of the 50 (2%) healthy subjects had an abnormal waveform. The difference in the distribution of normal Doppler waveform pattern between the patients and the control group was significant (P 0.05). There was not any correlation between the degree of fat infiltration and the hepatic vein waveform pattern (P = 0.60). Conclusion: Patients with fatty liver has a high rate of an abnormal hepatic vein Doppler waveform pattern which can be biphasic or monophasic. We could not find a relation between the etiological factors for FIL and the occurrence of an abnormal HV Doppler waveform

  11. Proteomics in pulmonary research: selected methodical aspects

    Directory of Open Access Journals (Sweden)

    Martin Petrek

    2007-10-01

    Full Text Available Recent years witness rapid expansion of applications of proteomics to clinical research including non-malignant lung disorders. These developments bring along the need for standardisation of proteomic experiments. This paper briefly reviews basic methodical aspects of appliedproteomic studies using SELDI-TOF mass spectrometry platform as example but also emphasizes general aspects of quality assurance in proteomics. Key-words: lung proteome, quality assurance, SELDI-TOF MS

  12. Research into real-option evaluation method

    International Nuclear Information System (INIS)

    Shiba, Tsuyoshi; Wakamatsu, Hitoshi

    2002-03-01

    As an evaluational method for valuation of a corporation, an investment project, a research and development, or the evaluation technique of an enterprise strategy, a real option analysis attracts attention instead of conventional Discount Cash Flow method. The reason is that it can divert the technique for the option valuation in financial engineering to the decision-making process performed according to change in investment environment. Related references, the analysis tools, the application examples, etc. were investigated about the decision-making technique using real option analysis, and this investigation considered the application method to decision-making of the research and development at Japan Nuclear Cycle Development Institute. Consequently, since the feature is in real option analysis being the evaluation technique on condition of that business conditions and business itself also change, the real option analysis fits for evaluation of a research and development that business conditions were opaque and it turns out that the businesses are highly flexible. Moreover, it turns out that it fits also for evaluation of a capital concentration type investment issue like power plants. (author)

  13. Variance stabilization for computing and comparing grand mean waveforms in MEG and EEG.

    Science.gov (United States)

    Matysiak, Artur; Kordecki, Wojciech; Sielużycki, Cezary; Zacharias, Norman; Heil, Peter; König, Reinhard

    2013-07-01

    Grand means of time-varying signals (waveforms) across subjects in magnetoencephalography (MEG) and electroencephalography (EEG) are commonly computed as arithmetic averages and compared between conditions, for example, by subtraction. However, the prerequisite for these operations, homogeneity of the variance of the waveforms in time, and for most common parametric statistical tests also between conditions, is rarely met. We suggest that the heteroscedasticity observed instead results because waveforms may differ by factors and additive terms and follow a mixed model. We propose to apply the asinh-transformation to stabilize the variance in such cases. We demonstrate the homogeneous variance and the normal distributions of data achieved by this transformation using simulated waveforms, and we apply it to real MEG data and show its benefits. The asinh-transformation is thus an essential and useful processing step prior to computing and comparing grand mean waveforms in MEG and EEG. Copyright © 2013 Society for Psychophysiological Research.

  14. Facies Constrained Elastic Full Waveform Inversion

    KAUST Repository

    Zhang, Z.

    2017-05-26

    Current efforts to utilize full waveform inversion (FWI) as a tool beyond acoustic imaging applications, for example for reservoir analysis, face inherent limitations on resolution and also on the potential trade-off between elastic model parameters. Adding rock physics constraints does help to mitigate these issues. However, current approaches to add such constraints are based on averaged type rock physics regularization terms. Since the true earth model consists of different facies, averaging over those facies naturally leads to smoothed models. To overcome this, we propose a novel way to utilize facies based constraints in elastic FWI. A so-called confidence map is calculated and updated at each iteration of the inversion using both the inverted models and the prior information. The numerical example shows that the proposed method can reduce the cross-talks and also can improve the resolution of inverted elastic properties.

  15. Facies Constrained Elastic Full Waveform Inversion

    KAUST Repository

    Zhang, Z.; Zabihi Naeini, E.; Alkhalifah, Tariq Ali

    2017-01-01

    Current efforts to utilize full waveform inversion (FWI) as a tool beyond acoustic imaging applications, for example for reservoir analysis, face inherent limitations on resolution and also on the potential trade-off between elastic model parameters. Adding rock physics constraints does help to mitigate these issues. However, current approaches to add such constraints are based on averaged type rock physics regularization terms. Since the true earth model consists of different facies, averaging over those facies naturally leads to smoothed models. To overcome this, we propose a novel way to utilize facies based constraints in elastic FWI. A so-called confidence map is calculated and updated at each iteration of the inversion using both the inverted models and the prior information. The numerical example shows that the proposed method can reduce the cross-talks and also can improve the resolution of inverted elastic properties.

  16. Qualitative Descriptive Methods in Health Science Research.

    Science.gov (United States)

    Colorafi, Karen Jiggins; Evans, Bronwynne

    2016-07-01

    The purpose of this methodology paper is to describe an approach to qualitative design known as qualitative descriptive that is well suited to junior health sciences researchers because it can be used with a variety of theoretical approaches, sampling techniques, and data collection strategies. It is often difficult for junior qualitative researchers to pull together the tools and resources they need to embark on a high-quality qualitative research study and to manage the volumes of data they collect during qualitative studies. This paper seeks to pull together much needed resources and provide an overview of methods. A step-by-step guide to planning a qualitative descriptive study and analyzing the data is provided, utilizing exemplars from the authors' research. This paper presents steps to conducting a qualitative descriptive study under the following headings: describing the qualitative descriptive approach, designing a qualitative descriptive study, steps to data analysis, and ensuring rigor of findings. The qualitative descriptive approach results in a summary in everyday, factual language that facilitates understanding of a selected phenomenon across disciplines of health science researchers. © The Author(s) 2016.

  17. Centered Differential Waveform Inversion with Minimum Support Regularization

    KAUST Repository

    Kazei, Vladimir

    2017-05-26

    Time-lapse full-waveform inversion has two major challenges. The first one is the reconstruction of a reference model (baseline model for most of approaches). The second is inversion for the time-lapse changes in the parameters. Common model approach is utilizing the information contained in all available data sets to build a better reference model for time lapse inversion. Differential (Double-difference) waveform inversion allows to reduce the artifacts introduced into estimates of time-lapse parameter changes by imperfect inversion for the baseline-reference model. We propose centered differential waveform inversion (CDWI) which combines these two approaches in order to benefit from both of their features. We apply minimum support regularization commonly used with electromagnetic methods of geophysical exploration. We test the CDWI method on synthetic dataset with random noise and show that, with Minimum support regularization, it provides better resolution of velocity changes than with total variation and Tikhonov regularizations in time-lapse full-waveform inversion.

  18. Synchronous Generator Model Parameter Estimation Based on Noisy Dynamic Waveforms

    Science.gov (United States)

    Berhausen, Sebastian; Paszek, Stefan

    2016-01-01

    In recent years, there have occurred system failures in many power systems all over the world. They have resulted in a lack of power supply to a large number of recipients. To minimize the risk of occurrence of power failures, it is necessary to perform multivariate investigations, including simulations, of power system operating conditions. To conduct reliable simulations, the current base of parameters of the models of generating units, containing the models of synchronous generators, is necessary. In the paper, there is presented a method for parameter estimation of a synchronous generator nonlinear model based on the analysis of selected transient waveforms caused by introducing a disturbance (in the form of a pseudorandom signal) in the generator voltage regulation channel. The parameter estimation was performed by minimizing the objective function defined as a mean square error for deviations between the measurement waveforms and the waveforms calculated based on the generator mathematical model. A hybrid algorithm was used for the minimization of the objective function. In the paper, there is described a filter system used for filtering the noisy measurement waveforms. The calculation results of the model of a 44 kW synchronous generator installed on a laboratory stand of the Institute of Electrical Engineering and Computer Science of the Silesian University of Technology are also given. The presented estimation method can be successfully applied to parameter estimation of different models of high-power synchronous generators operating in a power system.

  19. Synthetic tsunami waveform catalogs with kinematic constraints

    Science.gov (United States)

    Baptista, Maria Ana; Miranda, Jorge Miguel; Matias, Luis; Omira, Rachid

    2017-07-01

    In this study we present a comprehensive methodology to produce a synthetic tsunami waveform catalogue in the northeast Atlantic, east of the Azores islands. The method uses a synthetic earthquake catalogue compatible with plate kinematic constraints of the area. We use it to assess the tsunami hazard from the transcurrent boundary located between Iberia and the Azores, whose western part is known as the Gloria Fault. This study focuses only on earthquake-generated tsunamis. Moreover, we assume that the time and space distribution of the seismic events is known. To do this, we compute a synthetic earthquake catalogue including all fault parameters needed to characterize the seafloor deformation covering the time span of 20 000 years, which we consider long enough to ensure the representability of earthquake generation on this segment of the plate boundary. The computed time and space rupture distributions are made compatible with global kinematic plate models. We use the tsunami empirical Green's functions to efficiently compute the synthetic tsunami waveforms for the dataset of coastal locations, thus providing the basis for tsunami impact characterization. We present the results in the form of offshore wave heights for all coastal points in the dataset. Our results focus on the northeast Atlantic basin, showing that earthquake-induced tsunamis in the transcurrent segment of the Azores-Gibraltar plate boundary pose a minor threat to coastal areas north of Portugal and beyond the Strait of Gibraltar. However, in Morocco, the Azores, and the Madeira islands, we can expect wave heights between 0.6 and 0.8 m, leading to precautionary evacuation of coastal areas. The advantages of the method are its easy application to other regions and the low computation effort needed.

  20. Pulsatile pipe flow transition: Flow waveform effects

    Science.gov (United States)

    Brindise, Melissa C.; Vlachos, Pavlos P.

    2018-01-01

    Although transition is known to exist in various hemodynamic environments, the mechanisms that govern this flow regime and their subsequent effects on biological parameters are not well understood. Previous studies have investigated transition in pulsatile pipe flow using non-physiological sinusoidal waveforms at various Womersley numbers but have produced conflicting results, and multiple input waveform shapes have yet to be explored. In this work, we investigate the effect of the input pulsatile waveform shape on the mechanisms that drive the onset and development of transition using particle image velocimetry, three pulsatile waveforms, and six mean Reynolds numbers. The turbulent kinetic energy budget including dissipation rate, production, and pressure diffusion was computed. The results show that the waveform with a longer deceleration phase duration induced the earliest onset of transition, while the waveform with a longer acceleration period delayed the onset of transition. In accord with the findings of prior studies, for all test cases, turbulence was observed to be produced at the wall and either dissipated or redistributed into the core flow by pressure waves, depending on the mean Reynolds number. Turbulent production increased with increasing temporal velocity gradients until an asymptotic limit was reached. The turbulence dissipation rate was shown to be independent of mean Reynolds number, but a relationship between the temporal gradients of the input velocity waveform and the rate of turbulence dissipation was found. In general, these results demonstrated that the shape of the input pulsatile waveform directly affected the onset and development of transition.

  1. Radiation methods in research of ancient monuments

    International Nuclear Information System (INIS)

    Cechak, T.; Gerndt, J.; Kubelik, M.; Musilek, L.; Pavlik, Milan

    2000-01-01

    A 'Laboratory of Quantitative Methods in Monument Research' is being built at the CTU Prague. Its primary orientation is the investigation of historic architecture, although other objects of art can also be investigated. In the first phase, two radiation methods are being established, but it is set up in such a way, that various other methods can readily be added in its future development. The radiation methods chosen for the initial development of the laboratory are: thermoluminescence dating and X-ray fluorescence analysis. The design of the automated TL-reader, built in our laboratories, is adjusted for the purpose of dating of historic brick architecture (which, of course, does not exclude applications for ceramics and other materials). The investigation of renaissance architecture in southern Bohemia and Moravia is under preparation as the first large campaign of this kind in the Czech Republic. Radionuclide X-ray fluorescence analysis has been chosen as the basic analytical method in the laboratory. The possibility of analyses of paintings and fired building materials (bricks, roof tiles) have been investigated. The first results in both the areas are very promising

  2. Educational research methods for researching innovations in teaching, learning and assessment: The nursing lecturer as researcher.

    Science.gov (United States)

    Marks-Maran, Diane

    2015-11-01

    The author, who has had previous experience as a nurse researcher, has been engaged in helping nurse lecturers to undertake evaluation research studies into innovations in their teaching, learning and assessment methods. In order to undertake this work successfully, it was important to move from thinking like a nurse researcher to thinking like an educational researcher and developing the role of the nursing lecturer as researcher of their teaching. This article explores the difference between evaluation and evaluation research and argues for the need to use educational research methods when undertaking evaluation research into innovations in teaching, learning and assessment. A new model for educational evaluation research is presented together with two case examples of the model in use. The model has been tested on over 30 research studies into innovations in teaching, learning and assessment over the past 8 years. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Augmented kludge waveforms for detecting extreme-mass-ratio inspirals

    Science.gov (United States)

    Chua, Alvin J. K.; Moore, Christopher J.; Gair, Jonathan R.

    2017-08-01

    The extreme-mass-ratio inspirals (EMRIs) of stellar-mass compact objects into massive black holes are an important class of source for the future space-based gravitational-wave detector LISA. Detecting signals from EMRIs will require waveform models that are both accurate and computationally efficient. In this paper, we present the latest implementation of an augmented analytic kludge (AAK) model, publicly available at https://github.com/alvincjk/EMRI_Kludge_Suite as part of an EMRI waveform software suite. This version of the AAK model has improved accuracy compared to its predecessors, with two-month waveform overlaps against a more accurate fiducial model exceeding 0.97 for a generic range of sources; it also generates waveforms 5-15 times faster than the fiducial model. The AAK model is well suited for scoping out data analysis issues in the upcoming round of mock LISA data challenges. A simple analytic argument shows that it might even be viable for detecting EMRIs with LISA through a semicoherent template bank method, while the use of the original analytic kludge in the same approach will result in around 90% fewer detections.

  4. A nonlinear approach of elastic reflection waveform inversion

    KAUST Repository

    Guo, Qiang

    2016-09-06

    Elastic full waveform inversion (EFWI) embodies the original intention of waveform inversion at its inception as it is a better representation of the mostly solid Earth. However, compared with the acoustic P-wave assumption, EFWI for P- and S-wave velocities using multi-component data admitted mixed results. Full waveform inversion (FWI) is a highly nonlinear problem and this nonlinearity only increases under the elastic assumption. Reflection waveform inversion (RWI) can mitigate the nonlinearity by relying on transmissions from reflections focused on inverting low wavenumber components of the model. In our elastic endeavor, we split the P- and S-wave velocities into low wavenumber and perturbation components and propose a nonlinear approach to invert for both of them. The new optimization problem is built on an objective function that depends on both background and perturbation models. We utilize an equivalent stress source based on the model perturbation to generate reflection instead of demigrating from an image, which is applied in conventional RWI. Application on a slice of an ocean-bottom data shows that our method can efficiently update the low wavenumber parts of the model, but more so, obtain perturbations that can be added to the low wavenumbers for a high resolution output.

  5. A nonlinear approach of elastic reflection waveform inversion

    KAUST Repository

    Guo, Qiang; Alkhalifah, Tariq Ali

    2016-01-01

    Elastic full waveform inversion (EFWI) embodies the original intention of waveform inversion at its inception as it is a better representation of the mostly solid Earth. However, compared with the acoustic P-wave assumption, EFWI for P- and S-wave velocities using multi-component data admitted mixed results. Full waveform inversion (FWI) is a highly nonlinear problem and this nonlinearity only increases under the elastic assumption. Reflection waveform inversion (RWI) can mitigate the nonlinearity by relying on transmissions from reflections focused on inverting low wavenumber components of the model. In our elastic endeavor, we split the P- and S-wave velocities into low wavenumber and perturbation components and propose a nonlinear approach to invert for both of them. The new optimization problem is built on an objective function that depends on both background and perturbation models. We utilize an equivalent stress source based on the model perturbation to generate reflection instead of demigrating from an image, which is applied in conventional RWI. Application on a slice of an ocean-bottom data shows that our method can efficiently update the low wavenumber parts of the model, but more so, obtain perturbations that can be added to the low wavenumbers for a high resolution output.

  6. Metering error quantification under voltage and current waveform distortion

    Science.gov (United States)

    Wang, Tao; Wang, Jia; Xie, Zhi; Zhang, Ran

    2017-09-01

    With integration of more and more renewable energies and distortion loads into power grid, the voltage and current waveform distortion results in metering error in the smart meters. Because of the negative effects on the metering accuracy and fairness, it is an important subject to study energy metering combined error. In this paper, after the comparing between metering theoretical value and real recorded value under different meter modes for linear and nonlinear loads, a quantification method of metering mode error is proposed under waveform distortion. Based on the metering and time-division multiplier principles, a quantification method of metering accuracy error is proposed also. Analyzing the mode error and accuracy error, a comprehensive error analysis method is presented which is suitable for new energy and nonlinear loads. The proposed method has been proved by simulation.

  7. Strategies for the characteristic extraction of gravitational waveforms

    International Nuclear Information System (INIS)

    Babiuc, M. C.; Bishop, N. T.; Szilagyi, B.; Winicour, J.

    2009-01-01

    We develop, test, and compare new numerical and geometrical methods for improving the accuracy of extracting waveforms using characteristic evolution. The new numerical method involves use of circular boundaries to the stereographic grid patches which cover the spherical cross sections of the outgoing null cones. We show how an angular version of numerical dissipation can be introduced into the characteristic code to damp the high frequency error arising form the irregular way the circular patch boundary cuts through the grid. The new geometric method involves use of the Weyl tensor component Ψ 4 to extract the waveform as opposed to the original approach via the Bondi news function. We develop the necessary analytic and computational formula to compute the O(1/r) radiative part of Ψ 4 in terms of a conformally compactified treatment of null infinity. These methods are compared and calibrated in test problems based upon linearized waves.

  8. CSM research: Methods and application studies

    Science.gov (United States)

    Knight, Norman F., Jr.

    1989-01-01

    Computational mechanics is that discipline of applied science and engineering devoted to the study of physical phenomena by means of computational methods based on mathematical modeling and simulation, utilizing digital computers. The discipline combines theoretical and applied mechanics, approximation theory, numerical analysis, and computer science. Computational mechanics has had a major impact on engineering analysis and design. When applied to structural mechanics, the discipline is referred to herein as computational structural mechanics. Complex structures being considered by NASA for the 1990's include composite primary aircraft structures and the space station. These structures will be much more difficult to analyze than today's structures and necessitate a major upgrade in computerized structural analysis technology. NASA has initiated a research activity in structural analysis called Computational Structural Mechanics (CSM). The broad objective of the CSM activity is to develop advanced structural analysis technology that will exploit modern and emerging computers, such as those with vector and/or parallel processing capabilities. Here, the current research directions for the Methods and Application Studies Team of the Langley CSM activity are described.

  9. Evaluation of surface-wave waveform modeling for lithosphere velocity structure

    Science.gov (United States)

    Chang, Tao-Ming

    Surface-waveform modeling methods will become standard tools for studying the lithosphere structures because they can place greater constraints on earth structure and because of interest in the three-dimensional earth. The purpose of this study is to begin to learn the applicabilities and limitations of these methods. A surface-waveform inversion method is implemented using generalized seismological data functional theory. The method has been tested using synthetic and real seismic data and show that this method is well suited for teleseismic and regional seismograms. Like other linear inversion problems, this method also requires a good starting model. To ease reliance on good starting models, a global search technique, the genetic algorithm, has been applied to surface waveform modeling. This method can rapidly find good models for explaining surface-wave waveform at regional distance. However, this implementation also reveals that criteria which are widely used in seismological studies are not good enough to indicate the goodness of waveform fit. These two methods with the linear waveform inversion method, and traditional surface wave dispersion inversion method have been applied to a western Texas earthquake to test their abilities. The focal mechanism of the Texas event has been reestimated using a grid search for surface wave spectral amplitudes. A comparison of these four algorithms shows some interesting seismic evidences for lithosphere structure.

  10. Micro-seismic waveform matching inversion based on gravitational search algorithm and parallel computation

    Science.gov (United States)

    Jiang, Y.; Xing, H. L.

    2016-12-01

    Micro-seismic events induced by water injection, mining activity or oil/gas extraction are quite informative, the interpretation of which can be applied for the reconstruction of underground stress and monitoring of hydraulic fracturing progress in oil/gas reservoirs. The source characterises and locations are crucial parameters that required for these purposes, which can be obtained through the waveform matching inversion (WMI) method. Therefore it is imperative to develop a WMI algorithm with high accuracy and convergence speed. Heuristic algorithm, as a category of nonlinear method, possesses a very high convergence speed and good capacity to overcome local minimal values, and has been well applied for many areas (e.g. image processing, artificial intelligence). However, its effectiveness for micro-seismic WMI is still poorly investigated; very few literatures exits that addressing this subject. In this research an advanced heuristic algorithm, gravitational search algorithm (GSA) , is proposed to estimate the focal mechanism (angle of strike, dip and rake) and source locations in three dimension. Unlike traditional inversion methods, the heuristic algorithm inversion does not require the approximation of green function. The method directly interacts with a CPU parallelized finite difference forward modelling engine, and updating the model parameters under GSA criterions. The effectiveness of this method is tested with synthetic data form a multi-layered elastic model; the results indicate GSA can be well applied on WMI and has its unique advantages. Keywords: Micro-seismicity, Waveform matching inversion, gravitational search algorithm, parallel computation

  11. Efficient full waveform inversion using the excitation representation of the source wavefield

    KAUST Repository

    Kalita, Mahesh; Alkhalifah, Tariq Ali

    2017-01-01

    Full waveform inversion (FWI) is an iterative method of data-fitting, aiming at high-resolution recovery of the unknown model parameters. However, its conventional implementation is a cumbersome process, requiring a long computational time and large

  12. Inverting reflections using full-waveform inversion with inaccurate starting models

    KAUST Repository

    AlTheyab, Abdullah; Schuster, Gerard T.

    2015-01-01

    We present a method for inverting seismic reflections using full-waveform inversion (FWI) with inaccurate starting models. For a layered medium, near-offset reflections (with zero angle of incidence) are unlikely to be cycle-skipped regardless

  13. Flow pumping system for physiological waveforms.

    Science.gov (United States)

    Tsai, William; Savaş, Omer

    2010-02-01

    A pulsatile flow pumping system is developed to replicate flow waveforms with reasonable accuracy for experiments simulating physiological blood flows at numerous points in the body. The system divides the task of flow waveform generation between two pumps: a gear pump generates the mean component and a piston pump generates the oscillatory component. The system is driven by two programmable servo controllers. The frequency response of the system is used to characterize its operation. The system has been successfully tested in vascular flow experiments where sinusoidal, carotid, and coronary flow waveforms are replicated.

  14. The Documentary Method in Intercultural Research Scenarios

    Directory of Open Access Journals (Sweden)

    Henrike Evers

    2009-01-01

    Full Text Available The documentary method appears to be especially suitable for preventing possible ethnocentrisms in the interpretation of data in reconstructive research, as well as for precluding concessions with a statistic and normative cultural concept. As an illustration of this thesis, this article presents a study—undertaken at the Bremen University of Applied Sciences—in which the effects of an intercultural contact programme between international students and German families are analysed. Special emphasis is placed on the question of the students' emotional and cognitive changes, called educational processes ("Bildung" in the educational science. The theoretical and methodological background of the study and exemplary results are presented. URN: urn:nbn:de:0114-fqs0901478

  15. Variation of Pressure Waveforms in Measurements of Extracorporeal Shock Wave Lithotripter

    Science.gov (United States)

    Inose, Naoto; Ide, Masao

    1993-05-01

    In this paper, we describe measurement of variation in pressure waveforms of the acoustic field of an extra-corporeal shock-wave lithotripter (ESWL). Variations in the measured acoustic fields and pressure waveform of an underwater spark-gap-type ESWL with an exhausted spark plug electrode have been reported by researchers using crystal sensors. If the ESWL spark plugs become exhausted, patients feel pain during kidney, biliary stone disintegration. We studied the relationship between exhaustion of electrodes and the variation of pressure waveforms and shock-wave fields of the ESWL using a newly developed hydrophone.

  16. Toward Generating More Diagnostic Features from Photoplethysmogram Waveforms

    Directory of Open Access Journals (Sweden)

    Mohamed Elgendi

    2018-03-01

    Full Text Available Photoplethysmogram (PPG signals collected using a pulse oximeter are increasingly being used for screening and diagnosis purposes. Because of the non-invasive, cost-effective, and easy-to-use nature of the pulse oximeter, clinicians and biomedical engineers are investigating how PPG signals can help in the management of many medical conditions, especially for global health application. The study of PPG signal analysis is relatively new compared to research in electrocardiogram signals, for instance; however, we anticipate that in the near future blood pressure, cardiac output, and other clinical parameters will be measured from wearable devices that collect PPG signals, based on the signal’s vast potential. This article attempts to organize and standardize the names of PPG waveforms to ensure consistent terminologies, thereby helping the rapid developments in this research area, decreasing the disconnect within and among different disciplines, and increasing the number of features generated from PPG waveforms.

  17. Toward Generating More Diagnostic Features from Photoplethysmogram Waveforms.

    Science.gov (United States)

    Elgendi, Mohamed; Liang, Yongbo; Ward, Rabab

    2018-03-11

    Photoplethysmogram (PPG) signals collected using a pulse oximeter are increasingly being used for screening and diagnosis purposes. Because of the non-invasive, cost-effective, and easy-to-use nature of the pulse oximeter, clinicians and biomedical engineers are investigating how PPG signals can help in the management of many medical conditions, especially for global health application. The study of PPG signal analysis is relatively new compared to research in electrocardiogram signals, for instance; however, we anticipate that in the near future blood pressure, cardiac output, and other clinical parameters will be measured from wearable devices that collect PPG signals, based on the signal's vast potential. This article attempts to organize and standardize the names of PPG waveforms to ensure consistent terminologies, thereby helping the rapid developments in this research area, decreasing the disconnect within and among different disciplines, and increasing the number of features generated from PPG waveforms.

  18. The Modularized Software Package ASKI - Full Waveform Inversion Based on Waveform Sensitivity Kernels Utilizing External Seismic Wave Propagation Codes

    Science.gov (United States)

    Schumacher, F.; Friederich, W.

    2015-12-01

    We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full

  19. The Influence of Measurement Methodology on the Accuracy of Electrical Waveform Distortion Analysis

    Science.gov (United States)

    Bartman, Jacek; Kwiatkowski, Bogdan

    2018-04-01

    The present paper covers a review of documents that specify measurement methods of voltage waveform distortion. It also presents measurement stages of waveform components that are uncommon in the classic fundamentals of electrotechnics and signal theory, including the creation process of groups and subgroups of harmonics and interharmonics. Moreover, the paper discusses selected distortion factors of periodic waveforms and presents analyses that compare the values of these distortion indices. The measurements were carried out in the cycle per cycle mode and the measurement methodology that was used complies with the IEC 61000-4-7 norm. The studies showed significant discrepancies between the values of analyzed parameters.

  20. An Iterative Travel Time Inversion and Waveform Modeling Method to Determine the Crust Structure and Focal Mechanism: Case Study of 2015 Alxa Left Banner Ms5.8 Earthquake

    Science.gov (United States)

    Song, C.; Ge, Z.

    2017-12-01

    The boundary region between Alxa Block and Ordos Block is an area of stress concentration with strong seismicity and frequent small earthquakes. However, the knowledge of this area is limited since only a few seismic stations were deployed in this area. The 2015 Ms5.8 Alxa Left Banner Earthquake on April 15 is the largest one occurred in the surroundings since the 1976 Ms6.2 Bayinmuren Earthquake. Abundant stations built in the northern part of Chinese North-South Seismic Belt recorded this event sequence well within short distance, which provides us a great opportunity to carry out studies. We use these data to obtain a mean 1-D layered velocity structure via iterative inversion based on both travel time and waveform misfits. Then we use the travel time difference between data and synthetic seismograms to relocate the epicenter. Finally we invert the best double-couple focal mechanism and centroid depths of the source. As the result, the source is located at (39.7027° N, 106.4207° E) with a depth of 18 km and Mw 5.28. Nodal plane Ⅰ has strike 86°, dip angle 90° and slip angle -3°, while plane Ⅱ has strike 176°, dip angle 87° and slip angle 180°. Considering the dynamic structure of regional fault zone, we believe this earthquake is caused by a nearly pure left-lateral strike-slip fault with nodal plane Ⅰ being the fault plane. The seismogenic structure is likely to be an E-W striking buried fault nearby. There develops several groups of NE, NEE and E-W striking faults in Jilantai tectonic zone, parts of which have been verified by geophysical investigations. But we still know little about the dynamic nature of them. From our study, the corresponding fault of this event may indicate all groups of faults with same E-W strike has the common character of large-dip left-lateral strike-slip. Moreover, there may be some buried faults being newly born or not found yet. These results could be an important supplement to the future research of seismicity and

  1. A narrative method for consciousness research

    Science.gov (United States)

    Díaz, José-Luis

    2013-01-01

    Some types of first-person narrations of mental processes that constitute phenomenological accounts and texts, such as internal monolog statements, epitomize the best expressions and representations of human consciousness available and therefore may be used to model phenomenological streams of consciousness. The type of autonomous monolog in which an author or narrator declares actual mental processes in a think aloud manner seems particularly suitable for modeling streams of consciousness. A narrative method to extract and depict conscious processes, operations, contents, and states from an acceptable phenomenological text would require three subsequent steps: operational criteria for producing and/or selecting a phenomenological text, a system for detecting text items that are indicative of conscious contents and processes, and a procedure for representing such items in formal dynamic system devices such as Petri nets. The requirements and restrictions of each of these steps are presented, analyzed, and applied to phenomenological texts in the following manner: (1) the relevance of introspective language and narrative analyses to consciousness research and the idea that specific narratives are of paramount interest for such investigation is justified; (2) some of the obstacles and constraints to attain plausible consciousness inferences from narrative texts and the methodological requirements to extract and depict items relevant to consciousness contents and operations from a suitable phenomenological text are examined; (3) a preliminary exercise of the proposed method is used to analyze and chart a classical interior monolog excerpted from James Joyce’s Ulysses, a masterpiece of the stream-of-consciousness literary technique and, finally, (4) an inter-subjective evaluation for inter-observer agreement of mental attributions of another phenomenological text (an excerpt from the Intimate Journal of Miguel de Unamuno) is presented using some mathematical tools

  2. A narrative method for consciousness research

    Directory of Open Access Journals (Sweden)

    José-Luis eDíaz

    2013-11-01

    Full Text Available Some types of first person narrations of mental processes that constitute phenomenological parliaments and texts, such as internal monologue statements, epitomize the best expressions and representations of human consciousness available and therefore may be used to model phenomenological streams of consciousness. The type of autonomous monologue in which an author or narrator declares actual mental processes in a think aloud manner seems particularly suitable for modeling streams of consciousness. A narrative method to extract and depict conscious processes, operations, contents, and states from an acceptable phenomenological text would require three subsequent steps: operational criteria for producing and/or selecting a phenomenological text, a system for detecting text items that are indicative of conscious contents and processes, and a procedure for representing such items in formal dynamic system devices such as Petri nets. The requirements and restrictions of each of these steps are presented, analyzed, and applied to phenomenological texts in the following manner: (1 The relevance of introspective language and narrative analyses to consciousness research and the idea that specific narratives are of paramount interest for such investigation is justified; (2 Some of the obstacles and constraints to attain plausible consciousness inferences from narrative texts and the methodological requirements to extract and depict items relevant to consciousness contents and operations from a suitable phenomenological text are examined; (3 A preliminary exercise of the proposed method is used to analyze and chart a classical interior monologue excerpted from James Joyce’s Ulysses, a masterpiece of the stream-of-consciousness literary technique and, finally, an inter-subjective evaluation for inter-observer agreement of mental attributions of another phenomenological text (an excerpt from the Intimate Journal of Miguel de Unamuno is presented using some

  3. A narrative method for consciousness research.

    Science.gov (United States)

    Díaz, José-Luis

    2013-01-01

    Some types of first-person narrations of mental processes that constitute phenomenological accounts and texts, such as internal monolog statements, epitomize the best expressions and representations of human consciousness available and therefore may be used to model phenomenological streams of consciousness. The type of autonomous monolog in which an author or narrator declares actual mental processes in a think aloud manner seems particularly suitable for modeling streams of consciousness. A narrative method to extract and depict conscious processes, operations, contents, and states from an acceptable phenomenological text would require three subsequent steps: operational criteria for producing and/or selecting a phenomenological text, a system for detecting text items that are indicative of conscious contents and processes, and a procedure for representing such items in formal dynamic system devices such as Petri nets. The requirements and restrictions of each of these steps are presented, analyzed, and applied to phenomenological texts in the following manner: (1) the relevance of introspective language and narrative analyses to consciousness research and the idea that specific narratives are of paramount interest for such investigation is justified; (2) some of the obstacles and constraints to attain plausible consciousness inferences from narrative texts and the methodological requirements to extract and depict items relevant to consciousness contents and operations from a suitable phenomenological text are examined; (3) a preliminary exercise of the proposed method is used to analyze and chart a classical interior monolog excerpted from James Joyce's Ulysses, a masterpiece of the stream-of-consciousness literary technique and, finally, (4) an inter-subjective evaluation for inter-observer agreement of mental attributions of another phenomenological text (an excerpt from the Intimate Journal of Miguel de Unamuno) is presented using some mathematical tools.

  4. Demystifying Mixed Methods Research Design: A Review of the Literature

    OpenAIRE

    Gail D. Caruth

    2013-01-01

    Mixed methods research evolved in response to the observed limitations of both quantitative and qualitative designs and is a more complex method. The purpose of this paper was to examine mixed methods research in an attempt to demystify the design thereby allowing those less familiar with its design an opportunity to utilize it in future research. A review of the literature revealed that it has been gaining acceptance among researchers, researchers have begun using mixed methods research, it ...

  5. ASPECTS REGARDING NEUROMARKETING SPECIFIC RESEARCH METHODS

    Directory of Open Access Journals (Sweden)

    MIRELA-CRISTINA VOICU

    2012-05-01

    Full Text Available Information is one of the most important resources that a company must posses. Some informations are hidden deep in the black box - the mind of the consumer. Neuromarketing helps us find what is inside of the black box without troubling the consumer with questions that he doesn’t want to answer or that he can’t answer. Today because of an extensive research in mapping cortical and subcortical activity in association with behaviors and thoughts, the confidence in neurological data is growing. Thanks to discoveries in perceptual sciences we can identify the parts of the brain that are responsible for the phenomena that we experience daily. For all those interested in information obtained through neuromarketing techniques it becomes evident that there are corresponding neural substrates of consumer decision making process and these substrates can be observed, measured, and possibly manipulated. The following paper reveals some important aspects of the use of neuromarketing in studying consumer behavior by presenting the concepts, methods and techniques used under this sophisticated name, the limitations and advantages of using neuromarketing techniques and the importance of this type of information in decision making process at a company level.

  6. Exploring Reticence in Research Methods: The Experience of Studying Psychological Research Methods in Higher Education

    Science.gov (United States)

    Kingsley, Barbara E.; Robertson, Julia M.

    2017-01-01

    As a fundamental element of any psychology degree, the teaching and learning of research methods is repeatedly brought into sharp focus, and it is often regarded as a real challenge by undergraduate students. The reasons for this are complex, but frequently attributed to an aversion of maths. To gain a more detailed understanding of students'…

  7. Qualitative methods: a research approach worth considering

    African Journals Online (AJOL)

    Qualitative research forms part of the classical cycle of research. ... putting aside any preconceived ideas and “intuiting”- focusing on the ... that is, no new information is obtained. ... and communication with the scientific community are adhered.

  8. Waveform inversion for acoustic VTI media in frequency domain

    KAUST Repository

    Wu, Zedong

    2016-09-06

    Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the background model using a single scattered wavefield from an inverted perturbation. However, current RWI methods are mostly based on isotropic media assumption. We extend the idea of the combining inversion for the background model and perturbations to address transversely isotropic with a vertical axis of symmetry (VTI) media taking into consideration of the optimal parameter sensitivity information. As a result, we apply Born modeling corresponding to perturbations in only for the variable e to derive the relative reflected waveform inversion formulation. To reduce the number of parameters, we assume the background part of η = ε and work with a single variable to describe the anisotropic part of the wave propagation. Thus, the optimization variables are the horizontal velocity v, η = ε and the e perturbation. Application to the anisotropic version of Marmousi model with a single frequency of 2.5 Hz shows that this method can converge to the accurate result starting from a linearly increasing isotropic initial velocity. Application to a real dataset demonstrates the versatility of the approach.

  9. "Reading" Mixed Methods Research: Contexts for Criticism

    Science.gov (United States)

    Freshwater, Dawn

    2007-01-01

    Health and social care researchers, in their haste to "belong" to academia, have adopted the system of mixed methodology research, overestimating its ability to reveal the truth and occasionally imprisoning their thought in one system. In this article, some of the assumptions underpinning mixed methodology research and its discourse are subjected…

  10. Closed-form Solution to Directly Design FACE Waveforms for Beampatterns Using Planar Array

    KAUST Repository

    Bouchoucha, Taha; Ahmed, Sajid; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    In multiple-input multiple-output radar systems, it is usually desirable to steer transmitted power in the region-of-interest. To do this, conventional methods optimize the waveform covariance matrix, R, for the desired beampattern, which is then used to generate actual transmitted waveforms. Both steps require constrained optimization, therefore, use iterative algorithms. The main challenges encountered in the existing approaches are the computational complexity and the design of waveforms to use in practice. In this paper, we provide a closed-form solution to design covariance matrix for the given beampattern using the planar array, which is then used to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope (FACE) waveforms. The proposed algorithm exploits the two-dimensional fast-Fourier-transform. The performance of our proposed algorithm is compared with existing methods that are based on semi-definite quadratic programming with the advantage of a considerably reduced complexity.

  11. Closed-form Solution to Directly Design FACE Waveforms for Beampatterns Using Planar Array

    KAUST Repository

    Bouchoucha, Taha

    2015-04-19

    In multiple-input multiple-output radar systems, it is usually desirable to steer transmitted power in the region-of-interest. To do this, conventional methods optimize the waveform covariance matrix, R, for the desired beampattern, which is then used to generate actual transmitted waveforms. Both steps require constrained optimization, therefore, use iterative algorithms. The main challenges encountered in the existing approaches are the computational complexity and the design of waveforms to use in practice. In this paper, we provide a closed-form solution to design covariance matrix for the given beampattern using the planar array, which is then used to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope (FACE) waveforms. The proposed algorithm exploits the two-dimensional fast-Fourier-transform. The performance of our proposed algorithm is compared with existing methods that are based on semi-definite quadratic programming with the advantage of a considerably reduced complexity.

  12. Doppler waveform study as indicator of change of portal pressure after administration of octreotide

    Science.gov (United States)

    Haider, Shahbaz; Hussain, Qurban; Tabassum, Sumera; Hussain, Bilal; Durrani, Muhammad Rasheed; Ahmed, Fayyaz

    2016-01-01

    Objective: To estimate the effect of portal pressure lowering drug ‘octreotide’, by observing the Doppler waveform before and after the administration of intravenous bolus of octreotide and thus to assess indirectly its efficacy to lower the portal pressure. Methods: This quassi experimental study was carried out in Medical Department in collaboration with Radiology Department of Jinnah Postgraduate Medical Center Karachi Pakistan from September 10, 2015 to February 5, 2016. Cases were selected from patients admitted in Medical Wards and those attending Medical OPD. Diagnosis of cirrhosis was confirmed by Clinical Examination and Lab & Imaging investigation in Medical Department. Doppler waveform study was done by experienced radiologist in Radiology Department before and after administration of octreotide. Doppler signals were obtained from the right hepatic vein. Waveform tracings were recorded for five seconds and categorized as ‘monophasic’, ‘biphasic’ and ‘triphasic’. Waveform changes from one waveform to other were noted and analyzed. Results: Significant change i.e. from ‘monophasic’ to ‘biphasic’ or ‘biphasic’ to ‘triphasic’ was seen in 56% cases while ‘monophasic’ to ‘triphasic’ was seen in 20% cases. No change was seen in 24% cases. Improvement in waveform reflects lowering of portal vein pressure. Conclusion: Non invasive Hepatic vein Doppler waveform study showed improvement in Doppler waveform after administration of octreotide in 76% cases. Doppler waveform study has the potential of becoming non invasive ‘follow up tool’ of choice for assessing portal pressure in patients having variceal bleed due to portal hypertension. PMID:27648043

  13. Research on fiber Bragg grating heart sound sensing and wavelength demodulation method

    Science.gov (United States)

    Zhang, Cheng; Miao, Chang-Yun; Gao, Hua; Gan, Jing-Meng; Li, Hong-Qiang

    2010-11-01

    Heart sound includes a lot of physiological and pathological information of heart and blood vessel. Heart sound detecting is an important method to gain the heart status, and has important significance to early diagnoses of cardiopathy. In order to improve sensitivity and reduce noise, a heart sound measurement method based on fiber Bragg grating was researched. By the vibration principle of plane round diaphragm, a heart sound sensor structure of fiber Bragg grating was designed and a heart sound sensing mathematical model was established. A formula of heart sound sensitivity was deduced and the theoretical sensitivity of the designed sensor is 957.11pm/KPa. Based on matched grating method, the experiment system was built, by which the excursion of reflected wavelength of the sensing grating was detected and the information of heart sound was obtained. Experiments show that the designed sensor can detect the heart sound and the reflected wavelength variety range is about 70pm. When the sampling frequency is 1 KHz, the extracted heart sound waveform by using the db4 wavelet has the same characteristics with a standard heart sound sensor.

  14. Transient waveform acquisition system for the ELMO Bumpy Torus

    International Nuclear Information System (INIS)

    Young, K.G.; Burris, R.D.; Hillis, D.H.; Overbey, D.R.

    1984-10-01

    The transient waveform system described in this report is designed to acquire analog waveforms from the ELMO Bumpy Torus (EBT) diagnostic experiments. Pressure, density, synchrotron radiation, etc., are acquired and digitized with a Kinetic Systems TR812 transient recorder and associated modules located in a CAMAC crate. The system can simultaneously acquire, display, and transmit sets of data consisting of identification parameters and up to 1024 data points for 1 to 64 input signals (frequency range = 0.01 pulse/s to 100 kHz) of data every one or more minutes; thus, it can run continuously without operator intervention. The data are taken on a VAX 11/780 and transmitted to a data base on a DECSystem-10. To aid the programmer in making future modifications to the system, detailed documentation using the Yourdon structural methods has been given

  15. Image-domain full waveform inversion: Field data example

    KAUST Repository

    Zhang, Sanzong

    2014-08-05

    The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is the result of cycle skipping which degrades the low-wavenumber update in the absence of low-frequencies and long-offset data. An image-domain objective function is defined as the normed difference between the predicted and observed common image gathers (CIGs) in the subsurface offset domain. This new objective function is not constrained by cycle skipping at the far subsurface offsets. To test the effectiveness of this method, we apply it to marine data recorded in the Gulf of Mexico. Results show that image-domain FWI is less sensitive to the initial model and the absence of low-frequency data compared with conventional FWI. The liability, however, is that it is almost an order of magnitude more expensive than standard FWI.

  16. Image-domain full waveform inversion: Field data example

    KAUST Repository

    Zhang, Sanzong; Schuster, Gerard T.

    2014-01-01

    The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is the result of cycle skipping which degrades the low-wavenumber update in the absence of low-frequencies and long-offset data. An image-domain objective function is defined as the normed difference between the predicted and observed common image gathers (CIGs) in the subsurface offset domain. This new objective function is not constrained by cycle skipping at the far subsurface offsets. To test the effectiveness of this method, we apply it to marine data recorded in the Gulf of Mexico. Results show that image-domain FWI is less sensitive to the initial model and the absence of low-frequency data compared with conventional FWI. The liability, however, is that it is almost an order of magnitude more expensive than standard FWI.

  17. Handbook of Research Methods in Social and Personality Psychology

    Science.gov (United States)

    Reis, Harry T.; Judd, Charles M.

    2000-03-01

    This volume provides an overview of research methods in contemporary social psychology. Coverage includes conceptual issues in research design, methods of research, and statistical approaches. Because the range of research methods available for social psychology have expanded extensively in the past decade, both traditional and innovative methods are presented. The goal is to introduce new and established researchers alike to new methodological developments in the field.

  18. Toward a Conceptualization of Mixed Methods Phenomenological Research

    OpenAIRE

    Mayoh, Joanne; Onwuegbuzie, A.J.

    2015-01-01

    Increasingly, researchers are recognizing the benefits of expanding research designs that are rooted in one tradition (i.e., monomethod design) into a design that incorporates or interfaces with the other tradition. The flexibility of phenomenologically driven methods provides one such example. Indeed, phenomenological research methods work extremely well as a component of mixed methods research approaches. However, to date, a mixed methods version of phenomenological research has not been fo...

  19. Designing, Teaching, and Evaluating Two Complementary Mixed Methods Research Courses

    Science.gov (United States)

    Christ, Thomas W.

    2009-01-01

    Teaching mixed methods research is difficult. This longitudinal explanatory study examined how two classes were designed, taught, and evaluated. Curriculum, Research, and Teaching (EDCS-606) and Mixed Methods Research (EDCS-780) used a research proposal generation process to highlight the importance of the purpose, research question and…

  20. Full Waveform Inversion Using Nonlinearly Smoothed Wavefields

    KAUST Repository

    Li, Y.; Choi, Yun Seok; Alkhalifah, Tariq Ali; Li, Z.

    2017-01-01

    The lack of low frequency information in the acquired data makes full waveform inversion (FWI) conditionally converge to the accurate solution. An initial velocity model that results in data with events within a half cycle of their location in the observed data was required to converge. The multiplication of wavefields with slightly different frequencies generates artificial low frequency components. This can be effectively utilized by multiplying the wavefield with itself, which is nonlinear operation, followed by a smoothing operator to extract the artificially produced low frequency information. We construct the objective function using the nonlinearly smoothed wavefields with a global-correlation norm to properly handle the energy imbalance in the nonlinearly smoothed wavefield. Similar to the multi-scale strategy, we progressively reduce the smoothing width applied to the multiplied wavefield to welcome higher resolution. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to the conventional FWI except for the adjoint source. Examples on the Marmousi 2 model demonstrate the feasibility of the proposed FWI method to mitigate the cycle-skipping problem in the case of a lack of low frequency information.

  1. Full Waveform Inversion Using Nonlinearly Smoothed Wavefields

    KAUST Repository

    Li, Y.

    2017-05-26

    The lack of low frequency information in the acquired data makes full waveform inversion (FWI) conditionally converge to the accurate solution. An initial velocity model that results in data with events within a half cycle of their location in the observed data was required to converge. The multiplication of wavefields with slightly different frequencies generates artificial low frequency components. This can be effectively utilized by multiplying the wavefield with itself, which is nonlinear operation, followed by a smoothing operator to extract the artificially produced low frequency information. We construct the objective function using the nonlinearly smoothed wavefields with a global-correlation norm to properly handle the energy imbalance in the nonlinearly smoothed wavefield. Similar to the multi-scale strategy, we progressively reduce the smoothing width applied to the multiplied wavefield to welcome higher resolution. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to the conventional FWI except for the adjoint source. Examples on the Marmousi 2 model demonstrate the feasibility of the proposed FWI method to mitigate the cycle-skipping problem in the case of a lack of low frequency information.

  2. Debriefing Research Games : Context, Substance and Method

    NARCIS (Netherlands)

    van den Hoogen, J.; Lo, J.C.; Meijer, S.A.

    2016-01-01

    Background. Debriefing is an intrinsic part of games for learning and proper
    debriefing can also be beneficial to research games. However, the literature
    on how to debrief research games is sparse and only provides the professional
    with an abstract topic guide.
    Aim. The purpose of

  3. Variation and Commonality in Phenomenographic Research Methods

    Science.gov (United States)

    Akerlind, Gerlese S.

    2012-01-01

    This paper focuses on the data analysis stage of phenomenographic research, elucidating what is involved in terms of both commonality and variation in accepted practice. The analysis stage of phenomenographic research is often not well understood. This paper helps to clarify the process, initially by collecting together in one location the more…

  4. Methodical Problems in Organic Farming Research

    OpenAIRE

    Schäfer, Winfried

    2002-01-01

    Workshop presentation with particular focus on values, transferability and praxis relevance of organic farming research. Examples from agricultural engineering lead to the conclusion, that prototype farming, goal oriented project management, participative decision making and funding, coaching of co-operation, and coaching of conflict management may enhance long term, holistic and interdisciplinary research.

  5. Basic Research Methods for Librarians, Fifth Edition

    CERN Document Server

    Connaway, Lynn Silipigni

    2010-01-01

    Fifty-nine percent of the respondents to a 2000 survey reported that their master's programs had not adequately prepared them to conduct research, something that has not changed much in the ensuing decade. Yet, many library and information services (LIS) practitioners are routinely called upon to conducted job-related research. Where can they turn for the guidance they need?

  6. Design of pulse waveform for waveform division multiple access UWB wireless communication system.

    Science.gov (United States)

    Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu

    2014-01-01

    A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.

  7. SGRAPH (SeismoGRAPHer): Seismic waveform analysis and integrated tools in seismology

    Science.gov (United States)

    Abdelwahed, Mohamed F.

    2012-03-01

    Although numerous seismological programs are currently available, most of them suffer from the inability to manipulate different data formats and the lack of embedded seismological tools. SeismoGRAPHer, or simply SGRAPH, is a new system for maintaining and analyzing seismic waveform data in a stand-alone, Windows-based application that manipulates a wide range of data formats. SGRAPH was intended to be a tool sufficient for performing basic waveform analysis and solving advanced seismological problems. The graphical user interface (GUI) utilities and the Windows functionalities, such as dialog boxes, menus, and toolbars, simplify the user interaction with the data. SGRAPH supports common data formats, such as SAC, SEED, GSE, ASCII, and Nanometrics Y-format, and provides the ability to solve many seismological problems with built-in inversion tools. Loaded traces are maintained, processed, plotted, and saved as SAC, ASCII, or PS (post script) file formats. SGRAPH includes Generalized Ray Theory (GRT), genetic algorithm (GA), least-square fitting, auto-picking, fast Fourier transforms (FFT), and many additional tools. This program provides rapid estimation of earthquake source parameters, location, attenuation, and focal mechanisms. Advanced waveform modeling techniques are provided for crustal structure and focal mechanism estimation. SGRAPH has been employed in the Egyptian National Seismic Network (ENSN) as a tool assisting with routine work and data analysis. More than 30 users have been using previous versions of SGRAPH in their research for more than 3 years. The main features of this application are ease of use, speed, small disk space requirements, and the absence of third-party developed components. Because of its architectural structure, SGRAPH can be interfaced with newly developed methods or applications in seismology. A complete setup file, including the SGRAPH package with the online user guide, is available.

  8. Photoplethysmographic signal waveform index for detection of increased arterial stiffness

    International Nuclear Information System (INIS)

    Pilt, K; Meigas, K; Ferenets, R; Temitski, K; Viigimaa, M

    2014-01-01

    The aim of this research was to assess the validity of the photoplethysmographic (PPG) waveform index PPGAI for the estimation of increased arterial stiffness. For this purpose, PPG signals were recorded from 24 healthy subjects and from 20 type II diabetes patients. The recorded PPG signals were processed with the analysis algorithm developed and the waveform index PPGAI similar to the augmentation index (AIx) was calculated. As a reference, the aortic AIx was assessed and normalized for a heart rate of 75 bpm (AIx@75) by a SphygmoCor device. A strong correlation (r = 0.85) between the PPGAI and the aortic AIx@75 and a positive correlation of both indices with age were found. Age corrections for the indices PPGAI and AIx@75 as regression models from the signals of healthy subjects were constructed. Both indices revealed a significant difference between the groups of diabetes patients and healthy controls. However, the PPGAI provided the best statistical discrimination for the group of subjects with increased arterial stiffness. The waveform index PPGAI based on the inexpensive PPG technology can be considered as a perspective measure of increased arterial stiffness estimation in clinical screenings. (paper)

  9. Respiratory Physiology and the Impact of Different Modes of Ventilation on the Photoplethysmographic Waveform

    Directory of Open Access Journals (Sweden)

    Kirk H. Shelley

    2012-02-01

    Full Text Available The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter.  Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor.  This article will explore the response of the pulse oximeter waveform to various modes of ventilation.  Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform.

  10. Respiratory physiology and the impact of different modes of ventilation on the photoplethysmographic waveform.

    Science.gov (United States)

    Alian, Aymen A; Shelley, Kirk H

    2012-01-01

    The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform.

  11. Innovative Interpretive Qualitative Case Study Research Method ...

    African Journals Online (AJOL)

    lc2o

    The combined use of case study and systems theory is rarely discussed in the ... Scott, 2002), the main benefit of doing qualitative research is the patience ..... Teaching ICT to teacher candidates ... English Language Teachers. London: Arnold.

  12. Empirical Bayes methods in road safety research.

    NARCIS (Netherlands)

    Vogelesang, R.A.W.

    1997-01-01

    Road safety research is a wonderful combination of counting fatal accidents and using a toolkit containing prior, posterior, overdispersed Poisson, negative binomial and Gamma distributions, together with positive and negative regression effects, shrinkage estimators and fiercy debates concerning

  13. Nuclear physics methods in materials research

    International Nuclear Information System (INIS)

    1980-01-01

    The brochure contains the abstracts of the papers presented at the 7th EPS meeting 1980 in Darmstadt. The main subjects were: a) Neutron scattering and Moessbauer effect in materials research, b) ion implantation in micrometallurgy, c) applications of nuclear reactions and radioisotopes in research on solids, d) recent developments in activation analysis and e) pions, positrons, and heavy ions applied in solid state physics. (RW) [de

  14. Quality; Research of method; Consumer of satisfaction

    Directory of Open Access Journals (Sweden)

    Altamir da Silva Souza

    2004-01-01

    Full Text Available The customers' evaluation is an indicator used by the concerned organizations with the quality services. Starting from a research of evaluation of the quality services of a company of public cleaning, accomplished the denizen close to, we decided to elaborate this paper to present the found results and a critical analysis of the methodology used by the company. The research outcomes indicate a positive evaluation of the services. However, some changes are suggested on the adopted procedures.

  15. A sequential mixed methods research approach to investigating HIV ...

    African Journals Online (AJOL)

    2016-09-03

    Sep 3, 2016 ... Sequential mixed methods research is an effective approach for ... show the effectiveness of the research method. ... qualitative data before quantitative datasets ..... whereby both types of data are collected simultaneously.

  16. Within-footprint roughness measurements using ICESat/GLAS waveform and LVIS elevation

    International Nuclear Information System (INIS)

    Li, Xiaolu; Xu, Kai; Xu, Lijun

    2016-01-01

    The surface roughness is an important characteristic over an ice sheet or glacier, since it is an identification of boundary-layer meteorology and is an important limiter on the accuracy of surface-height measurements. In this paper, we propose a simulation method to derive the within-footprint roughness (called simulation-derived roughness) using ICESat/GLAS echo waveform, laser vegetation imaging sensor (LVIS) elevations, and laser profile array (LPA) images of ICESat/GLAS. By dividing the within-footprint surface into several elements, a simulation echo waveform can be obtained as the sum of the elementary pulses reflected from each surface element. The elevation of the surface elements, which is utilized to get the return time of the elementary pulses, is implemented based on an LVIS interpolated elevation using a radial basis function (RBF) neural network. The intensity of the elementary pulses can be obtained from the thresholded LPA images. Based on the return time and the intensity of the elementary pulses, we used the particle swarm optimization (PSO) method to approximate the simulation waveform to the ICESat/GLAS echo waveform. The full width at half maximum) (FWHM) of the elementary pulse was extracted from the simulation waveform for estimating the simulation-derived roughness. By comparing with the elevation-derived roughness (derived from the elevation) and the waveform-derived roughness (derived from the ICESat/GLAS waveform), the proposed algorithm can exclude the slope effect from waveform width broadening for describing the roughness of the surface elements. (paper)

  17. Using mixed methods research in medical education: basic guidelines for researchers.

    Science.gov (United States)

    Schifferdecker, Karen E; Reed, Virginia A

    2009-07-01

    Mixed methods research involves the collection, analysis and integration of both qualitative and quantitative data in a single study. The benefits of a mixed methods approach are particularly evident when studying new questions or complex initiatives and interactions, which is often the case in medical education research. Basic guidelines for when to use mixed methods research and how to design a mixed methods study in medical education research are not readily available. The purpose of this paper is to remedy that situation by providing an overview of mixed methods research, research design models relevant for medical education research, examples of each research design model in medical education research, and basic guidelines for medical education researchers interested in mixed methods research. Mixed methods may prove superior in increasing the integrity and applicability of findings when studying new or complex initiatives and interactions in medical education research. They deserve an increased presence and recognition in medical education research.

  18. Research method of nuclear patent information

    International Nuclear Information System (INIS)

    Mo Dan; Gao An'na; Sun Chenglin; Wang Lei; You Xinfeng

    2010-01-01

    When faced with a huge amount of nuclear patent information, the key to effective research include: (1) Choose convenient way to search, quick access to nuclear technology related patents; (2) To overcome the language barrier, analysis the technical content of patent information; (3) Organize the publication date of retrieved patent documents, analysis the status and trends of nuclear technology development; (4) Research the patented technology of main applicants; (5) Always pay attention to the legal status of patent information, free use the invalid patents, at the same time avoid the patent infringement. Summary, patent information is important to obtain the latest technical information source, and the research work of patent information is a comprehensive understanding and mastery way for advanced nuclear technology. (authors)

  19. The use of mixed methods research in interdisciplinary educational journals

    OpenAIRE

    López-Fernández, Olatz; Molina Azorín, José Francisco

    2011-01-01

    Mixed methods research is becoming increasingly important in several scientific areas. The analysis of prevalence rates is a new line of research that has emerged in mixed methods research, and this methodological approach has only been applied carefully in a handful of journals. The purpose of this article was to analyse the prevalence of mixed methods research in interdisciplinary educational journals. Moreover, the main characteristics of the mixed methods articles identified were examined...

  20. Nuclear physics methods in materials research

    International Nuclear Information System (INIS)

    Bethge, K.; Baumann, H.; Jex, H.; Rauch, F.

    1980-01-01

    Proceedings of the seventh divisional conference of the Nuclear Physics Division held at Darmstadt, Germany, from 23rd through 26th of September, 1980. The scope of this conference was defined as follows: i) to inform solid state physicists and materials scientists about the application of nuclear physics methods; ii) to show to nuclear physicists open questions and problems in solid state physics and materials science to which their methods can be applied. According to the intentions of the conference, the various nuclear physics methods utilized in solid state physics and materials science and especially new developments were reviewed by invited speakers. Detailed aspects of the methods and typical examples extending over a wide range of applications were presented as contributions in poster sessions. The Proceedings contain all the invited papers and about 90% of the contributed papers. (orig./RW)

  1. [Research on the preparative method of Arctigenin].

    Science.gov (United States)

    Zhang, Li-Ying; Yang, Yi-Shun; Zhang, Tong; Ding, Yue; Cai, Zhen-Zhen; Tao, Jian-Sheng

    2012-03-01

    To research on the preparation of Arctigenin in vitro. Took enzyme concentration, time course and substrate concentration as investigation factors, used Box-Behnken design-response surface methodology to optimize the enzyme hydrolysis path of Arctigenin. The best operational path for Arctigenin was as follows: the temperature was 50 degrees C, pH was 4.8, enzyme concentration was 0.44 U/mL, time course was 46.81 min, substrate concentration was 0.29 mg/mL, the conversion rate was 90.94%. This research can be regarded as a referencein preparing Arctigenin in vitro.

  2. Diversified Research Methods Education in LIS: Thinking outside the Box

    Science.gov (United States)

    Luo, Lili

    2017-01-01

    A small number of LIS degree programs have adopted a diversified approach to research methods education, including offering an array of specialized research methods courses in addition to a general introductory course. The current study conducted an in-depth investigation of the diversified research methods curriculum of the LIS program at San…

  3. Development of a Research Methods and Statistics Concept Inventory

    Science.gov (United States)

    Veilleux, Jennifer C.; Chapman, Kate M.

    2017-01-01

    Research methods and statistics are core courses in the undergraduate psychology major. To assess learning outcomes, it would be useful to have a measure that assesses research methods and statistical literacy beyond course grades. In two studies, we developed and provided initial validation results for a research methods and statistical knowledge…

  4. Critical Debates in Teaching Research Methods in the Social Sciences

    Science.gov (United States)

    Gunn, Andrew

    2017-01-01

    This paper explores some of the critical debates in social science research methods education and is set out in three parts. The first section introduces the importance and relevance of research methods to the social sciences. It then outlines the problems and challenges experienced in the teaching and learning of research methods, which are…

  5. Demystifying Mixed Methods Research Design: A Review of the Literature

    Science.gov (United States)

    Caruth, Gail D.

    2013-01-01

    Mixed methods research evolved in response to the observed limitations of both quantitative and qualitative designs and is a more complex method. The purpose of this paper was to examine mixed methods research in an attempt to demystify the design thereby allowing those less familiar with its design an opportunity to utilize it in future research.…

  6. A Synthesis of the Literature on Research Methods Education

    Science.gov (United States)

    Earley, Mark A.

    2014-01-01

    The purpose of this research synthesis is to examine the current research on teaching and learning research methods. The aims are to understand the themes present in the current literature and identify gaps in our understanding of how we teach, and how students learn, research methods. A synthesis of 89 studies generated three themes: (1)…

  7. Market Research Methods for Improving College Responsiveness.

    Science.gov (United States)

    Larkin, Paul G.

    1979-01-01

    Essential elements of a good marketing plan for higher education institutions are described. What market research is and how the modern concept of marketing differs from the traditional sales approach are discussed as well as market analysis and definition. Also included is a discussion of marketing for proposed new programs. (Author/SF)

  8. Innovations in Second Language Research Methods.

    Science.gov (United States)

    Gass, Susan M.

    2001-01-01

    Focuses on two approaches to research in second language acquisition: (1) various types of acceptability judgments or probes aimed at assessing acquisition of syntactic structure; and (2) various types of stimulated recall designed to gather learners' accounts of their own thought processes. (Author/VWL)

  9. Methodologies and Methods for User Behavioral Research.

    Science.gov (United States)

    Wang, Peiling

    1999-01-01

    Discusses methodological issues in empirical studies of information-related behavior in six specific research areas: information needs and uses; information seeking; relevance judgment; online searching (including online public access catalog, online database, and the Web); human-system interactions; and reference transactions. (Contains 191…

  10. Signal processing in noise waveform radar

    CERN Document Server

    Kulpa, Krzysztof

    2013-01-01

    This book is devoted to the emerging technology of noise waveform radar and its signal processing aspects. It is a new kind of radar, which use noise-like waveform to illuminate the target. The book includes an introduction to basic radar theory, starting from classical pulse radar, signal compression, and wave radar. The book then discusses the properties, difficulties and potential of noise radar systems, primarily for low-power and short-range civil applications. The contribution of modern signal processing techniques to making noise radar practical are emphasized, and application examples

  11. The application of mixed methods designs to trauma research.

    Science.gov (United States)

    Creswell, John W; Zhang, Wanqing

    2009-12-01

    Despite the use of quantitative and qualitative data in trauma research and therapy, mixed methods studies in this field have not been analyzed to help researchers designing investigations. This discussion begins by reviewing four core characteristics of mixed methods research in the social and human sciences. Combining these characteristics, the authors focus on four select mixed methods designs that are applicable in trauma research. These designs are defined and their essential elements noted. Applying these designs to trauma research, a search was conducted to locate mixed methods trauma studies. From this search, one sample study was selected, and its characteristics of mixed methods procedures noted. Finally, drawing on other mixed methods designs available, several follow-up mixed methods studies were described for this sample study, enabling trauma researchers to view design options for applying mixed methods research in trauma investigations.

  12. The laddering method in service innovation research

    DEFF Research Database (Denmark)

    Grünbaum, Niels Nolsøe

    2017-01-01

    The laddering method is a qualitative interview technique applied in a situation with one interviewer and one informant with the aim of creating an understanding of the value that business-to-consumer (B2C) customers extract from product attributes. Thus, this methodology aims to depict a mental ...

  13. Pollination Research Methods with Apis mellifera

    Science.gov (United States)

    This chapter describes field and lab procedures for doing experiments on honey bee pollination. Most of the methods apply to any insect for whom pollen vectoring capacity is the question. What makes honey bee pollination distinctive is its historic emphasis on agricultural applications; hence one fi...

  14. Research Investigation of Information Access Methods

    Science.gov (United States)

    Heinrichs, John H.; Sharkey, Thomas W.; Lim, Jeen-Su

    2006-01-01

    This study investigates the satisfaction of library users at Wayne State University who utilize alternative information access methods. The LibQUAL+[TM] desired and perceived that satisfaction ratings are used to determine the user's "superiority gap." By focusing limited library resources to address "superiority gap" issues identified by each…

  15. Mixed Methods and Action Research: similar or different?

    OpenAIRE

    Wiśniewska, Danuta

    2011-01-01

    This article attempts to analyse and compare ELT studies grounded solely in mixed methods and ELT action research studies based on a mixed methods approach in order to identify to what degree action research studies combining different methods in a single study comply with the principles of rigorous mixed methods study.

  16. Transformative, Mixed Methods Checklist for Psychological Research with Mexican Americans

    Science.gov (United States)

    Canales, Genevieve

    2013-01-01

    This is a description of the creation of a research methods tool, the "Transformative, Mixed Methods Checklist for Psychological Research With Mexican Americans." For conducting literature reviews of and planning mixed methods studies with Mexican Americans, it contains evaluative criteria calling for transformative mixed methods, perspectives…

  17. Innovative Methods: Resources for Research, Publishing, and Teaching.

    Science.gov (United States)

    Gergen, Mary; Chrisler, Joan C.; LoCicero, Alice

    1999-01-01

    Reviews a selection of innovative methods congenial to research in feminist psychology and describes undergraduate and graduate courses that emphasize these methods in their curricula. Contains a bibliography of over 300 entries organized by type of innovative method. (SLD)

  18. Using Blogs in Qualitative Educational Research: An Exploration of Method

    Science.gov (United States)

    Harricharan, Michelle; Bhopal, Kalwant

    2014-01-01

    When compared with wider social research, qualitative educational research has been relatively slow to take up online research methods (ORMs). There is some very notable research in the area but, in general, ORMs have not achieved wide applicability in qualitative educational contexts apart from research that is inherently linked to the Internet,…

  19. Effects of respiratory manoeuvres on hepatic vein Doppler waveform and flow velocities in a healthy population

    International Nuclear Information System (INIS)

    Altinkaya, Naime; Koc, Zafer; Ulusan, Serife; Demir, Senay; Gurel, Kamil

    2011-01-01

    Objective: This study was performed to determine the variations in Doppler waveforms and flow velocity during respiratory manoeuvres in healthy individuals with no liver disease. Materials and methods: In total, 100 individuals (75 women and 25 men) without known cardiac or liver disease were examined prospectively with duplex Doppler ultrasonography (US). We recorded the Doppler waveforms and peak systolic velocities (V max ) of the middle hepatic vein during normal respiration, during breath-holding after quiet expiration and also during deep inspiration. Doppler waveforms are categorised as triphasic, biphasic or monophasic. Results: During normal respiration, hepatic venous waveforms were triphasic in 93% of subjects, monophasic in 6% and biphasic in 1%. During breath-holding after quiet expiration, the percentages were 91%, 6% and 3%, respectively. During deep inspiration, they were 80%, 18% and 2%, respectively. Although significant differences were noted between rates during deep inspiration and normal respiration, they were quite similar during normal respiration and breath-holding after quiet expiration (P max were significantly higher during normal respiration compared to quiet expiration and during quiet expiration compared to deep inspiration (P < 0.05). Conclusion: The velocities and waveforms of hepatic veins varied during respiratory manoeuvres. The status of respiration must be taken into consideration whilst examining the hepatic vein waveforms and velocities with duplex Doppler US.

  20. Plasma density calculation based on the HCN waveform data

    International Nuclear Information System (INIS)

    Chen Liaoyuan; Pan Li; Luo Cuiwen; Zhou Yan; Deng Zhongchao

    2004-01-01

    A method to improve the plasma density calculation is introduced using the base voltage and the phase zero points obtained from the HCN interference waveform data. The method includes making the signal quality higher by putting the signal control device and the analog-to-digit converters in the same location and charging them by the same power, and excluding the noise's effect according to the possible changing rate of the signal's phase, and to make the base voltage more accurate by dynamical data processing. (authors)

  1. Mixed-methods research in nursing - a critical review.

    Science.gov (United States)

    Bressan, Valentina; Bagnasco, Annamaria; Aleo, Giuseppe; Timmins, Fiona; Barisone, Michela; Bianchi, Monica; Pellegrini, Ramona; Sasso, Loredana

    2017-10-01

    To review the use of mixed-methods research in nursing with a particular focus on the extent to which current practice informs nurse researchers. It also aimed to highlight gaps in current knowledge, understanding and reporting of this type of research. Mixed-methods research is becoming increasingly popular among nurses and healthcare professionals. Emergent findings from this type of research are very useful for nurses in practice. The combination of both quantitative and qualitative methods provides a scientific base for practice but also richness from the qualitative enquiry. However, at the same time mixed-methods research is underdeveloped. This study identified mixed-methods research papers and critically evaluated their usefulness for research practice. To support the analysis, we performed a two-stage search using CINAHL to find papers with titles that included the key term 'mixed method'. An analysis of studies that used mixed-methods research revealed some inconsistencies in application and reporting. Attempts to use two distinct research methods in these studies often meant that one or both aspects had limitations. Overall methods were applied in a less rigorous way. This has implications for providing somewhat limited direction for novice researchers. There is also potential for application of evidence in healthcare practice that limited validity. This study highlights current gaps in knowledge, understanding and reporting of mixed-methods research. While these methods are useful to gain insight into clinical problems nurses lack guidance with this type of research. This study revealed that the guidance provided by current mixed-methods research is inconsistent and incomplete and this compounds the lack of available direction. There is an urgent need to develop robust guidelines for using mixed-methods research so that findings may be critically implemented in practice. © 2016 John Wiley & Sons Ltd.

  2. Research on new methods in transport theory

    International Nuclear Information System (INIS)

    Stefanovicj, D.

    1975-01-01

    Neutron transport theory is the basis for development of reactor theory and reactor calculational methods. It has to be acknowledged that recent applications of these disciplines have influenced considerably the development of power reactor concepts and technology. However, these achievements were implemented in a rather heuristic way, since the satisfaction of design demands were of utmost importance. Often this kind of approach turns out to be very restrictive and not even adequate for rather typical reactor applications. Many aspects and techniques of reactor theory and calculations ought to be reevaluated and/or reformulated on the more sound physical and mathematical foundations. At the same time, new reactor concepts and operational demands give rise to more sophisticated and complex design requirements. These new requirements can be met only by the development of new design techniques, which in the case of reactor neutronic calculation lead directly to the advanced transport theory methods. In addition, the rapid development of computer technology opens new opportunities for applications of advanced transport theory in practical calculations

  3. Vapor generation methods for explosives detection research

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  4. A multi-channel waveform digitizer system

    International Nuclear Information System (INIS)

    Bieser, F.; Muller, W.F.J.

    1990-01-01

    The authors report on the design and performance of a multichannel waveform digitizer system for use with the Multiple Sample Ionization Chamber (MUSIC) Detector at the Bevalac. 128 channels of 20 MHz Flash ADC plus 256 word deep memory are housed in a single crate. Digital thresholds and hit pattern logic facilitate zero suppression during readout which is performed over a standard VME bus

  5. Full-waveform inversion: Filling the gaps

    KAUST Repository

    Beydoun, Wafik B.; Alkhalifah, Tariq Ali

    2015-01-01

    After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi

  6. Qualitative Methods in Patient-Centered Outcomes Research.

    Science.gov (United States)

    Vandermause, Roxanne; Barg, Frances K; Esmail, Laura; Edmundson, Lauren; Girard, Samantha; Perfetti, A Ross

    2017-02-01

    The Patient-Centered Outcomes Research Institute (PCORI), created to fund research guided by patients, caregivers, and the broader health care community, offers a new research venue. Many (41 of 50) first funded projects involved qualitative research methods. This study was completed to examine the current state of the science of qualitative methodologies used in PCORI-funded research. Principal investigators participated in phenomenological interviews to learn (a) how do researchers using qualitative methods experience seeking funding for, implementing and disseminating their work; and (b) how may qualitative methods advance the quality and relevance of evidence for patients? Results showed the experience of doing qualitative research in the current research climate as "Being a bona fide qualitative researcher: Staying true to research aims while negotiating challenges," with overlapping patterns: (a) researching the elemental, (b) expecting surprise, and (c) pushing boundaries. The nature of qualitative work today was explicitly described and is rendered in this article.

  7. Innovative Methods and Applications in Mucoadhesion Research

    DEFF Research Database (Denmark)

    Mackie, Alan; Goycoolea, Francisco M.; Menchicchi, Bianca

    2017-01-01

    The present review is aimed at elucidating relatively new aspects of mucoadhesion/mucus interaction and related phenomena that emerged from a Mucoadhesion workshop held in Munster on 2–3 September 2015 as a satellite event of the ICCC 13th—EUCHIS 12th. After a brief outline of the new issues......, the focus is on mucus description, purification, and mucus/mucin characterization, all steps that are pivotal to the understanding of mucus related phenomena and the choice of the correct mucosal model for in vitro and ex vivo experiments, alternative bio/mucomimetic materials are also presented....... Then a selection of preparative techniques and testing methods are described (at molecular as well as micro and macroscale) that may support the pharmaceutical development of mucus interactive systems and assist formulators in the scale-up and industrialization steps. Recent applications of mucoadhesive systems...

  8. Source-independent elastic waveform inversion using a logarithmic wavefield

    KAUST Repository

    Choi, Yun Seok; Min, Dong Joon

    2012-01-01

    The logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating

  9. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints

    KAUST Repository

    Zhang, Zhendong; Alkhalifah, Tariq Ali; Naeini, Ehsan Zabihi; Sun, Bingbing

    2018-01-01

    Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like

  10. Multiparameter Elastic Full Waveform Inversion With Facies Constraints

    KAUST Repository

    Zhang, Zhendong; Alkhalifah, Tariq Ali; Naeini, Ehsan Zabihi

    2017-01-01

    Full waveform inversion (FWI) aims fully benefit from all the data characteristics to estimate the parameters describing the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion as a tool beyond acoustic

  11. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Jardak, Seifallah; Ahmed, Sajid; Alouini, Mohamed-Slim

    2014-01-01

    , the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.

  12. EPG waveform library for Graphocephala atropunctata (Hemiptera: Cicadellidae): Effect of adhesive, input resistor, and voltage levels on waveform appearance and stylet probing behaviors.

    Science.gov (United States)

    Cervantes, Felix A; Backus, Elaine A

    2018-05-31

    Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce's disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with input resistor (Ri) levels (amplifier sensitivities) of 10 6 , 10 7 , 10 8 and 10 9  Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (10 7 and 10 9  Ohms) was performed. Intermediate Ri levels 10 7 and 10 8  Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa

  13. Empowering and Engaging Students in Learning Research Methods

    Science.gov (United States)

    Liu, Shuang; Breit, Rhonda

    2013-01-01

    The capacity to conduct research is essential for university graduates to survive and thrive in their future career. However, research methods courses have often been considered by students as "abstract", "uninteresting", and "hard". Thus, motivating students to engage in the process of learning research methods has become a crucial challenge for…

  14. Strategy to Promote Active Learning of an Advanced Research Method

    Science.gov (United States)

    McDermott, Hilary J.; Dovey, Terence M.

    2013-01-01

    Research methods courses aim to equip students with the knowledge and skills required for research yet seldom include practical aspects of assessment. This reflective practitioner report describes and evaluates an innovative approach to teaching and assessing advanced qualitative research methods to final-year psychology undergraduate students. An…

  15. Towards full waveform ambient noise inversion

    Science.gov (United States)

    Sager, Korbinian; Ermert, Laura; Boehm, Christian; Fichtner, Andreas

    2018-01-01

    In this work we investigate fundamentals of a method—referred to as full waveform ambient noise inversion—that improves the resolution of tomographic images by extracting waveform information from interstation correlation functions that cannot be used without knowing the distribution of noise sources. The fundamental idea is to drop the principle of Green function retrieval and to establish correlation functions as self-consistent observables in seismology. This involves the following steps: (1) We introduce an operator-based formulation of the forward problem of computing correlation functions. It is valid for arbitrary distributions of noise sources in both space and frequency, and for any type of medium, including 3-D elastic, heterogeneous and attenuating media. In addition, the formulation allows us to keep the derivations independent of time and frequency domain and it facilitates the application of adjoint techniques, which we use to derive efficient expressions to compute first and also second derivatives. The latter are essential for a resolution analysis that accounts for intra- and interparameter trade-offs. (2) In a forward modelling study we investigate the effect of noise sources and structure on different observables. Traveltimes are hardly affected by heterogeneous noise source distributions. On the other hand, the amplitude asymmetry of correlations is at least to first order insensitive to unmodelled Earth structure. Energy and waveform differences are sensitive to both structure and the distribution of noise sources. (3) We design and implement an appropriate inversion scheme, where the extraction of waveform information is successively increased. We demonstrate that full waveform ambient noise inversion has the potential to go beyond ambient noise tomography based on Green function retrieval and to refine noise source location, which is essential for a better understanding of noise generation. Inherent trade-offs between source and structure

  16. Research and Design of Rootkit Detection Method

    Science.gov (United States)

    Liu, Leian; Yin, Zuanxing; Shen, Yuli; Lin, Haitao; Wang, Hongjiang

    Rootkit is one of the most important issues of network communication systems, which is related to the security and privacy of Internet users. Because of the existence of the back door of the operating system, a hacker can use rootkit to attack and invade other people's computers and thus he can capture passwords and message traffic to and from these computers easily. With the development of the rootkit technology, its applications are more and more extensive and it becomes increasingly difficult to detect it. In addition, for various reasons such as trade secrets, being difficult to be developed, and so on, the rootkit detection technology information and effective tools are still relatively scarce. In this paper, based on the in-depth analysis of the rootkit detection technology, a new kind of the rootkit detection structure is designed and a new method (software), X-Anti, is proposed. Test results show that software designed based on structure proposed is much more efficient than any other rootkit detection software.

  17. Reflections on Mixing Methods in Applied Linguistics Research

    Science.gov (United States)

    Hashemi, Mohammad R.

    2012-01-01

    This commentary advocates the use of mixed methods research--that is the integration of qualitative and quantitative methods in a single study--in applied linguistics. Based on preliminary findings from a research project in progress, some reflections on the current practice of mixing methods as a new trend in applied linguistics are put forward.…

  18. A Preliminary Rubric Design to Evaluate Mixed Methods Research

    Science.gov (United States)

    Burrows, Timothy J.

    2013-01-01

    With the increase in frequency of the use of mixed methods, both in research publications and in externally funded grants there are increasing calls for a set of standards to assess the quality of mixed methods research. The purpose of this mixed methods study was to conduct a multi-phase analysis to create a preliminary rubric to evaluate mixed…

  19. Design Patterns for Mixed-Method Research in HCI

    NARCIS (Netherlands)

    Robert Holwerda; Arthur Bennis; Lambert Zaad; René Bakker; Sabine Craenmehr; Stijn Hoppenbrouwers; Dick Lenior; Marjolein Jacobs; Koen van Turnhout; Ralph Niels

    2014-01-01

    In this paper we discuss mixed-method research in HCI. We report on an empirical literature study of the NordiCHI 2012 proceedings which aimed to uncover and describe common mixed-method approaches, and to identify good practices for mixed-methods research in HCI. We present our results as

  20. The development of the miniaturized waveform receiver with the function measuring Antenna Impedance in space plasmas

    Science.gov (United States)

    Ishii, H.; Kojima, H.; Fukuhara, H.; Okada, S.; Yamakawa, H.

    2012-04-01

    Plasma wave is one of the most essential physical quantities in the solar terrestrial physics. The role of plasma wave receiver onboard satellites is to detect plasma waves in space with a good signal to noise ratio. There are two types of plasma wave receivers, the sweep frequency analyzer and the waveform capture. While the sweep frequency analyzer provides plasma wave spectra, the waveform capture obtains waveforms with phase information that is significant in studying nonlinear phenomena. Antenna sensors to observe electric fields of the plasma waves show different features in plasmas from in vacuum. The antenna impedances have specific characteristics in the frequency domain because of the dispersion of plasmas. These antenna impedances are expressed with complex number. We need to know not only the antenna impedances but also the transfer functions of plasma wave receiver's circuits in order to calibrate observed waveforms precisely. The impedances of the electric field antennas are affected by a state of surrounding plasmas. Since satellites run through various regions with different plasma parameters, we precisely should measure the antenna impedances onboard spacecraft. On the contrary, we can obtain the plasma density and by measuring the antenna impedances. Several formulas of the antenna impedance measurement system were proposed. A synchronous detection method is used on the BepiColombo Mercury Magnetospheric Orbiter (MMO), which will be launched in 2014. The digital data are stored in the onboard memory. They are read out and converted to the analog waveforms by D/A converter. They are fed into the input of the preamplifiers of antenna sensors through a resistor. We can calculate a transfer function of the circuit by applying the synchronous detection method to the output waveform from waveform receivers and digital data as a signal source. The size of this system is same as an A5 board. In recent years, Application Specific Integrated Circuit (ASIC

  1. Development of optoelectronic monitoring system for ear arterial pressure waveforms

    Science.gov (United States)

    Sasayama, Satoshi; Imachi, Yu; Yagi, Tamotsu; Imachi, Kou; Ono, Toshirou; Man-i, Masando

    1994-02-01

    Invasive intra-arterial blood pressure measurement is the most accurate method but not practical if the subject is in motion. The apparatus developed by Wesseling et al., based on a volume-clamp method of Penaz (Finapres), is able to monitor continuous finger arterial pressure waveforms noninvasively. The limitation of Finapres is the difficulty in measuring the pressure of a subject during work that involves finger or arm action. Because the Finapres detector is attached to subject's finger, the measurements are affected by inertia of blood and hydrostatic effect cause by arm or finger motion. To overcome this problem, the authors made a detector that is attached to subject's ear and developed and optoelectronic monitoring systems for ear arterial pressure waveform (Earpres). An IR LEDs, photodiode, and air cuff comprised the detector. The detector was attached to a subject's ear, and the space adjusted between the air cuff and the rubber plate on which the LED and photodiode were positioned. To evaluate the accuracy of Earpres, the following tests were conducted with participation of 10 healthy male volunteers. The subjects rested for about five minutes, then performed standing and squatting exercises to provide wide ranges of systolic and diastolic arterial pressure. Intra- and inter-individual standard errors were calculated according to the method of van Egmond et al. As a result, average, the averages of intra-individual standard errors for earpres appeared small (3.7 and 2.7 mmHg for systolic and diastolic pressure respectively). The inter-individual standard errors for Earpres were about the same was Finapres for both systolic and diastolic pressure. The results showed the ear monitor was reliable in measuring arterial blood pressure waveforms and might be applicable to various fields such as sports medicine and ergonomics.

  2. [Application of Delphi method in traditional Chinese medicine clinical research].

    Science.gov (United States)

    Bi, Ying-fei; Mao, Jing-yuan

    2012-03-01

    In recent years, Delphi method has been widely applied in traditional Chinese medicine (TCM) clinical research. This article analyzed the present application situation of Delphi method in TCM clinical research, and discussed some problems presented in the choice of evaluation method, classification of observation indexes and selection of survey items. On the basis of present application of Delphi method, the author analyzed the method on questionnaire making, selection of experts, evaluation of observation indexes and selection of survey items. Furthermore, the author summarized the steps of application of Delphi method in TCM clinical research.

  3. Using mixed methods in music therapy health care research

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2015-01-01

    »Mixed methods« (or »multiple methods») is a fairly new concept in music therapy research. It is inspired by recent methodological developments in social science, covering the interaction of quantitative and qualitative methods in one and the same research study. Mixed methods are not the same...... as the diversity or pluralism of methods advocated by many scholars who are critical towards the principles of evidence-based medicine. This article presents a concrete example of mixed methods in music therapy research: a psycho-social study of music therapy with female cancer survivors. Problems related...

  4. The imagework method in health and social science research.

    Science.gov (United States)

    Edgar, I R

    1999-03-01

    Existing alongside the traditional forms of qualitative social science research, there is a set of potential research methods that derive from experiential groupwork and the humanistic human potential movement and are only slightly used by researchers. Social science research has barely begun to use these powerful strategies that were developed originally for personal and group change but that are potentially applicable to the research domain. This article will locate these methods within the qualitative research domain and propose a novel view of their value. The study of the actual and potential use of one of these methods, imagework, will be the particular focus of this article. References to the use of artwork, sculpting, psychodrama, gestalt, and dreamwork will also be made. The hypothesis underpinning the author's approach is that experiential research methods such as imagework can elicit implicit knowledge and self-identifies of respondents in a way that other methods cannot.

  5. A Review of Research Methods in Children's Technology Design

    DEFF Research Database (Denmark)

    Jensen, Janne Jul; Skov, Mikael B.

    2005-01-01

    Research methods have been objects of discussions for dec-ades and defining research methods is still a quite substan-tial challenge. However, it is important to understand how research methods have been adapted in different disciplines as it potentially informs us on future directions and influ......-ences on the discipline. Inspired by previous studies from other disciplines, we conduct a survey of research methods in paper publications. 105 papers on children's technology design are classified on a two-dimensional matrix on research method and pur-pose. Our results show a strong focus on engineering of products...... as applied research and on evaluation of devel-oped products in the field or in the lab. Also, we find that much research is conducted in natural setting environments with strong focus on field studies....

  6. Travelling Methods: Tracing the Globalization of Qualitative Communication Research

    Directory of Open Access Journals (Sweden)

    Bryan C. Taylor

    2016-05-01

    Full Text Available Existing discussion of the relationships between globalization, communication research, and qualitative methods emphasizes two images: the challenges posed by globalization to existing communication theory and research methods, and the impact of post-colonial politics and ethics on qualitative research. We draw in this paper on a third image – qualitative research methods as artifacts of globalization – to explore the globalization of qualitative communication research methods. Following a review of literature which tentatively models this process, we discuss two case studies of qualitative research in the disciplinary subfields of intercultural communication and media audience studies. These cases elaborate the forces which influence the articulation of national, disciplinary, and methodological identities which mediate the globalization of qualitative communication research methods.

  7. Mixed methods research design for pragmatic psychoanalytic studies.

    Science.gov (United States)

    Tillman, Jane G; Clemence, A Jill; Stevens, Jennifer L

    2011-10-01

    Calls for more rigorous psychoanalytic studies have increased over the past decade. The field has been divided by those who assert that psychoanalysis is properly a hermeneutic endeavor and those who see it as a science. A comparable debate is found in research methodology, where qualitative and quantitative methods have often been seen as occupying orthogonal positions. Recently, Mixed Methods Research (MMR) has emerged as a viable "third community" of research, pursuing a pragmatic approach to research endeavors through integrating qualitative and quantitative procedures in a single study design. Mixed Methods Research designs and the terminology associated with this emerging approach are explained, after which the methodology is explored as a potential integrative approach to a psychoanalytic human science. Both qualitative and quantitative research methods are reviewed, as well as how they may be used in Mixed Methods Research to study complex human phenomena.

  8. Children's Literature in the Undergraduate Course on Communication Research Methods

    Science.gov (United States)

    Brown, Daniel S.

    2010-01-01

    Objective: Students will develop positive attitudes toward communication research by linking new values and principles with the familiar values and principles contained in children's literature. Course: Communication Research Methods.

  9. Applying Mixed Methods Research at the Synthesis Level: An Overview

    Science.gov (United States)

    Heyvaert, Mieke; Maes, Bea; Onghena, Patrick

    2011-01-01

    Historically, qualitative and quantitative approaches have been applied relatively separately in synthesizing qualitative and quantitative evidence, respectively, in several research domains. However, mixed methods approaches are becoming increasingly popular nowadays, and practices of combining qualitative and quantitative research components at…

  10. Colloquy: The Methods and Merits of Pornography Research.

    Science.gov (United States)

    Linz, Daniel; And Others

    1988-01-01

    Daniel Linz and Edward Donnerstein criticize the research methods and conclusions of pornography researchers Dolf Zillmann and Jennings Bryant (who allege that consumption of pornography results in antisocial effects). Zillman and Bryant respond. (ARH)

  11. Frequency domain, waveform inversion of laboratory crosswell radar data

    Science.gov (United States)

    Ellefsen, Karl J.; Mazzella, Aldo T.; Horton, Robert J.; McKenna, Jason R.

    2010-01-01

    A new waveform inversion for crosswell radar is formulated in the frequency-domain for a 2.5D model. The inversion simulates radar waves using the vector Helmholtz equation for electromagnetic waves. The objective function is minimized using a backpropagation method suitable for a 2.5D model. The inversion is tested by processing crosswell radar data collected in a laboratory tank. The estimated model is consistent with the known electromagnetic properties of the tank. The formulation for the 2.5D model can be extended to inversions of acoustic and elastic data.

  12. The Design Social: Framing social research methods for design postgraduates.

    OpenAIRE

    Evans, Martyn

    2010-01-01

    This paper discusses approaches for framing social research methods within postgraduate design curricula, details the responses of postgraduate design students to the possibilities presented by social research methods, and concludes with a case study of the adoption experiences of PhD students in design when engaging with social research methods. Analysis of semi-structured interviews is employed to draw out perceptions and experiences of design postgraduates when engaging with social researc...

  13. Why, and how, mixed methods research is undertaken in health services research in England: a mixed methods study

    Science.gov (United States)

    O'Cathain, Alicia; Murphy, Elizabeth; Nicholl, Jon

    2007-01-01

    Background Recently, there has been a surge of international interest in combining qualitative and quantitative methods in a single study – often called mixed methods research. It is timely to consider why and how mixed methods research is used in health services research (HSR). Methods Documentary analysis of proposals and reports of 75 mixed methods studies funded by a research commissioner of HSR in England between 1994 and 2004. Face-to-face semi-structured interviews with 20 researchers sampled from these studies. Results 18% (119/647) of HSR studies were classified as mixed methods research. In the documentation, comprehensiveness was the main driver for using mixed methods research, with researchers wanting to address a wider range of questions than quantitative methods alone would allow. Interviewees elaborated on this, identifying the need for qualitative research to engage with the complexity of health, health care interventions, and the environment in which studies took place. Motivations for adopting a mixed methods approach were not always based on the intrinsic value of mixed methods research for addressing the research question; they could be strategic, for example, to obtain funding. Mixed methods research was used in the context of evaluation, including randomised and non-randomised designs; survey and fieldwork exploratory studies; and instrument development. Studies drew on a limited number of methods – particularly surveys and individual interviews – but used methods in a wide range of roles. Conclusion Mixed methods research is common in HSR in the UK. Its use is driven by pragmatism rather than principle, motivated by the perceived deficit of quantitative methods alone to address the complexity of research in health care, as well as other more strategic gains. Methods are combined in a range of contexts, yet the emerging methodological contributions from HSR to the field of mixed methods research are currently limited to the single

  14. Theoretical-methodical Fundamentals of industrial marketing research

    OpenAIRE

    Butenko, N.

    2009-01-01

    The article proves the necessity to research theoretical and methodical fundamentals of industrial marketing and defines main key aspects of relationship management with the customers on industrial market.

  15. Waveform inversion of lateral velocity variation from wavefield source location perturbation

    KAUST Repository

    Choi, Yun Seok

    2013-09-22

    It is challenge in waveform inversion to precisely define the deep part of the velocity model compared to the shallow part. The lateral velocity variation, or what referred to as the derivative of velocity with respect to the horizontal distance, with well log data can be used to update the deep part of the velocity model more precisely. We develop a waveform inversion algorithm to obtain the lateral velocity variation by inverting the wavefield variation associated with the lateral shot location perturbation. The gradient of the new waveform inversion algorithm is obtained by the adjoint-state method. Our inversion algorithm focuses on resolving the lateral changes of the velocity model with respect to a fixed reference vertical velocity profile given by a well log. We apply the method on a simple-dome model to highlight the methods potential.

  16. 2D acoustic-elastic coupled waveform inversion in the Laplace domain

    KAUST Repository

    Bae, Hoseuk

    2010-04-01

    Although waveform inversion has been intensively studied in an effort to properly delineate the Earth\\'s structures since the early 1980s, most of the time- and frequency-domain waveform inversion algorithms still have critical limitations in their applications to field data. This may be attributed to the highly non-linear objective function and the unreliable low-frequency components. To overcome the weaknesses of conventional waveform inversion algorithms, the acoustic Laplace-domain waveform inversion has been proposed. The Laplace-domain waveform inversion has been known to provide a long-wavelength velocity model even for field data, which may be because it employs the zero-frequency component of the damped wavefield and a well-behaved logarithmic objective function. However, its applications have been confined to 2D acoustic media.We extend the Laplace-domain waveform inversion algorithm to a 2D acoustic-elastic coupled medium, which is encountered in marine exploration environments. In 2D acoustic-elastic coupled media, the Laplace-domain pressures behave differently from those of 2D acoustic media, although the overall features are similar to each other. The main differences are that the pressure wavefields for acoustic-elastic coupled media show negative values even for simple geological structures unlike in acoustic media, when the Laplace damping constant is small and the water depth is shallow. The negative values may result from more complicated wave propagation in elastic media and at fluid-solid interfaces.Our Laplace-domain waveform inversion algorithm is also based on the finite-element method and logarithmic wavefields. To compute gradient direction, we apply the back-propagation technique. Under the assumption that density is fixed, P- and S-wave velocity models are inverted from the pressure data. We applied our inversion algorithm to the SEG/EAGE salt model and the numerical results showed that the Laplace-domain waveform inversion

  17. Transcranial motor evoked potential waveform changes in corrective fusion for adolescent idiopathic scoliosis.

    Science.gov (United States)

    Kobayashi, Kazuyoshi; Imagama, Shiro; Ito, Zenya; Ando, Kei; Hida, Tetsuro; Ito, Kenyu; Tsushima, Mikito; Ishikawa, Yoshimoto; Matsumoto, Akiyuki; Nishida, Yoshihiro; Ishiguro, Naoki

    2017-01-01

    OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers

  18. Workflow for near-surface velocity automatic estimation: Source-domain full-traveltime inversion followed by waveform inversion

    KAUST Repository

    Liu, Lu; Fei, Tong; Luo, Yi; Guo, Bowen

    2017-01-01

    This paper presents a workflow for near-surface velocity automatic estimation using the early arrivals of seismic data. This workflow comprises two methods, source-domain full traveltime inversion (FTI) and early-arrival waveform inversion. Source

  19. A typology of health marketing research methods--combining public relations methods with organizational concern.

    Science.gov (United States)

    Rotarius, Timothy; Wan, Thomas T H; Liberman, Aaron

    2007-01-01

    Research plays a critical role throughout virtually every conduit of the health services industry. The key terms of research, public relations, and organizational interests are discussed. Combining public relations as a strategic methodology with the organizational concern as a factor, a typology of four different research methods emerges. These four health marketing research methods are: investigative, strategic, informative, and verification. The implications of these distinct and contrasting research methods are examined.

  20. Adapting Western research methods to indigenous ways of knowing.

    Science.gov (United States)

    Simonds, Vanessa W; Christopher, Suzanne

    2013-12-01

    Indigenous communities have long experienced exploitation by researchers and increasingly require participatory and decolonizing research processes. We present a case study of an intervention research project to exemplify a clash between Western research methodologies and Indigenous methodologies and how we attempted reconciliation. We then provide implications for future research based on lessons learned from Native American community partners who voiced concern over methods of Western deductive qualitative analysis. Decolonizing research requires constant reflective attention and action, and there is an absence of published guidance for this process. Continued exploration is needed for implementing Indigenous methods alone or in conjunction with appropriate Western methods when conducting research in Indigenous communities. Currently, examples of Indigenous methods and theories are not widely available in academic texts or published articles, and are often not perceived as valid.

  1. Mixed Methods Research in School Psychology: A Mixed Methods Investigation of Trends in the Literature

    Science.gov (United States)

    Powell, Heather; Mihalas, Stephanie; Onwuegbuzie, Anthony J.; Suldo, Shannon; Daley, Christine E.

    2008-01-01

    This article illustrates the utility of mixed methods research (i.e., combining quantitative and qualitative techniques) to the field of school psychology. First, the use of mixed methods approaches in school psychology practice is discussed. Second, the mixed methods research process is described in terms of school psychology research. Third, the…

  2. Prototype of a transient waveform recording ASIC

    Science.gov (United States)

    Qin, J.; Zhao, L.; Cheng, B.; Chen, H.; Guo, Y.; Liu, S.; An, Q.

    2018-01-01

    The paper presents the design and measurement results of a transient waveform recording ASIC based on the Switched Capacitor Array (SCA) architecture. This 0.18 μm CMOS prototype device contains two channels and each channel employs a SCA of 128 samples deep, a 12-bit Wilkinson ADC and a serial data readout. A series of tests have been conducted and the results indicate that: a full 1 V signal voltage range is available, the input analog bandwidth is approximately 450 MHz and the sampling speed is adjustable from 0.076 to 3.2 Gsps (Gigabit Samples Per Second). For precision waveform timing extraction, careful calibration of timing intervals between samples is conducted to improve the timing resolution of such chips, and the timing precision of this ASIC is proved to be better than 15 ps RMS.

  3. Digitizing and analysis of neutron generator waveforms

    International Nuclear Information System (INIS)

    Bryant, T.C.

    1977-11-01

    All neutron generator waveforms from units tested at the SLA neutron generator test site are digitized and the digitized data stored in the CDC 6600 tape library for display and analysis using the CDC 6600 computer. The digitizing equipment consists mainly of seven Biomation Model 8100 transient recorders, Digital Equipment Corporation PDP 11/20 computer, RK05 disk, seven-track magnetic tape transport, and appropriate DEC and SLA controllers and interfaces. The PDP 11/20 computer is programmed in BASIC with assembly language drivers. In addition to digitizing waveforms, this equipment is used for other functions such as the automated testing of multiple-operation electronic neutron generators. Although other types of analysis have been done, the largest use of the digitized data has been for various types of graphical displays using the CDC 6600 and either the SD4020 or DX4460 plotters

  4. Programmable Clock Waveform Generation for CCD Readout

    Energy Technology Data Exchange (ETDEWEB)

    Vicente, J. de; Castilla, J.; Martinez, G.; Marin, J.

    2006-07-01

    Charge transfer efficiency in CCDs is closely related to the clock waveform. In this paper, an experimental framework to explore different FPGA based clock waveform generator designs is described. Two alternative design approaches for controlling the rise/fall edge times and pulse width of the CCD clock signal have been implemented: level-control and time-control. Both approaches provide similar characteristics regarding the edge linearity and noise. Nevertheless, dissimilarities have been found with respect to the area and frequency range of application. Thus, while the time-control approach consumes less area, the level control approach provides a wider range of clock frequencies since it does not suffer capacitor discharge effect. (Author) 8 refs.

  5. Induced waveform transitions of dissipative solitons

    Science.gov (United States)

    Kochetov, Bogdan A.; Tuz, Vladimir R.

    2018-01-01

    The effect of an externally applied force upon the dynamics of dissipative solitons is analyzed in the framework of the one-dimensional cubic-quintic complex Ginzburg-Landau equation supplemented by a potential term with an explicit coordinate dependence. The potential accounts for the external force manipulations and consists of three symmetrically arranged potential wells whose depth varies along the longitudinal coordinate. It is found out that under an influence of such potential a transition between different soliton waveforms coexisting under the same physical conditions can be achieved. A low-dimensional phase-space analysis is applied in order to demonstrate that by only changing the potential profile, transitions between different soliton waveforms can be performed in a controllable way. In particular, it is shown that by means of a selected potential, stationary dissipative soliton can be transformed into another stationary soliton as well as into periodic, quasi-periodic, and chaotic spatiotemporal dissipative structures.

  6. Computational Intelligence and Wavelet Transform Based Metamodel for Efficient Generation of Not-Yet Simulated Waveforms.

    Directory of Open Access Journals (Sweden)

    Gabriel Oltean

    Full Text Available The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms, efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer, and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination. The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each

  7. Computational Intelligence and Wavelet Transform Based Metamodel for Efficient Generation of Not-Yet Simulated Waveforms.

    Science.gov (United States)

    Oltean, Gabriel; Ivanciu, Laura-Nicoleta

    2016-01-01

    The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms), efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer), and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination). The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each parameter on the

  8. Computational Intelligence and Wavelet Transform Based Metamodel for Efficient Generation of Not-Yet Simulated Waveforms

    Science.gov (United States)

    Oltean, Gabriel; Ivanciu, Laura-Nicoleta

    2016-01-01

    The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms), efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer), and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination). The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each parameter on the

  9. Full-waveform inversion: Filling the gaps

    KAUST Repository

    Beydoun, Wafik B.

    2015-09-01

    After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi, UAE. The workshop was organized by SEG, and its partner sponsors were Saudi Aramco (gold sponsor), ExxonMobil, and CGG. Read More: http://library.seg.org/doi/10.1190/tle34091106.1

  10. Invisible nursing research: thoughts about mixed methods research and nursing practice.

    Science.gov (United States)

    Fawcett, Jacqueline

    2015-04-01

    In this this essay, the author addresses the close connection between mixed methods research and nursing practice. If the assertion that research and practice are parallel processes is accepted, then nursing practice may be considered "invisible mixed methods research," in that almost every encounter between a nurse and a patient involves collection and integration of qualitative (word) and quantitative (number) information that actually is single-case mixed methods research. © The Author(s) 2015.

  11. Time-dependent phase error correction using digital waveform synthesis

    Science.gov (United States)

    Doerry, Armin W.; Buskirk, Stephen

    2017-10-10

    The various technologies presented herein relate to correcting a time-dependent phase error generated as part of the formation of a radar waveform. A waveform can be pre-distorted to facilitate correction of an error induced into the waveform by a downstream operation/component in a radar system. For example, amplifier power droop effect can engender a time-dependent phase error in a waveform as part of a radar signal generating operation. The error can be quantified and an according complimentary distortion can be applied to the waveform to facilitate negation of the error during the subsequent processing of the waveform. A time domain correction can be applied by a phase error correction look up table incorporated into a waveform phase generator.

  12. Graduate Students' Expectations of an Introductory Research Methods Course

    Science.gov (United States)

    Earley, Mark A.

    2013-01-01

    While there is a scattered literature base on teaching research methods courses, there is very little literature that speaks to what and how students learn in research methods courses. Students are often described as coming to the course not seeing its relevance, bringing negative attitudes and low motivation with them. The purpose of this…

  13. Take It or Leave It: Students' Attitudes about Research Methods

    Science.gov (United States)

    Wisecup, Allison K.

    2017-01-01

    This study employs a cross-sectional design to explore sociology majors' attitudes toward research methods. Survey data from a convenience sample of students enrolled in 16 departments are used to compare the attitudes of students who have and have not completed a research methods course. Despite consistent anecdotal claims that students harbor…

  14. Mixed-methods approaches in health research in Nepal

    OpenAIRE

    Simkhada, Padam; Van Teijlingen, Edwin; Wasti, Sharada Prasad; Sathian, B.

    2014-01-01

    Combining and integrating a mixture of qualitative and quantitative methods in one single study is widely used in health and social care research in high-income countries. This editorial adds a few words of advice to the novice mixed-methods researcher in Nepal.

  15. Infusing Active Learning into the Research Methods Unit

    Science.gov (United States)

    Bluestone, Cheryl

    2007-01-01

    The research methods unit of survey psychology classes introduces important concepts of scientific reasoning and fluency, making it an ideal course in which to deliver enhanced curricula. To increase interest and engagement, the author developed an expanded research methods and statistics module to give students the opportunity to explore…

  16. Triangulation, Respondent Validation, and Democratic Participation in Mixed Methods Research

    Science.gov (United States)

    Torrance, Harry

    2012-01-01

    Over the past 10 years or so the "Field" of "Mixed Methods Research" (MMR) has increasingly been exerting itself as something separate, novel, and significant, with some advocates claiming paradigmatic status. Triangulation is an important component of mixed methods designs. Triangulation has its origins in attempts to validate research findings…

  17. Mixed Methods in Intervention Research: Theory to Adaptation

    Science.gov (United States)

    Nastasi, Bonnie K.; Hitchcock, John; Sarkar, Sreeroopa; Burkholder, Gary; Varjas, Kristen; Jayasena, Asoka

    2007-01-01

    The purpose of this article is to demonstrate the application of mixed methods research designs to multiyear programmatic research and development projects whose goals include integration of cultural specificity when generating or translating evidence-based practices. The authors propose a set of five mixed methods designs related to different…

  18. Intelligent Adjustment of Printhead Driving Waveform Parameters for 3D Electronic Printing

    Directory of Open Access Journals (Sweden)

    Lin Na

    2017-01-01

    Full Text Available In practical applications of 3D electronic printing, a major challenge is to adjust the printhead for a high print resolution and accuracy. However, an exhausting manual selective process inevitably wastes a lot of time. Therefore, in this paper, we proposed a new intelligent adjustment method, which adopts artificial bee colony algorithm to optimize the printhead driving waveform parameters for getting the desired printhead state. Experimental results show that this method can quickly and accuracy find out the suitable combination of driving waveform parameters to meet the needs of applications.

  19. Image-domain full waveform inversion

    KAUST Repository

    Zhang, Sanzong

    2013-08-20

    The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is because the waveform misfit function is highly nonlinear with respect to changes in velocity model. To reduce this nonlinearity, we define the image-domain objective function to minimize the difference of the suboffset-domain common image gathers (CIGs) obtained by migrating the observed data and the calculated data. The derivation shows that the gradient of this new objective function is the combination of the gradient of the conventional FWI and the image-domain differential semblance optimization (DSO). Compared to the conventional FWI, the imagedomain FWI is immune to cycle skipping problems by smearing the nonzero suboffset images along wavepath. It also can avoid the edge effects and the gradient artifacts that are inherent in DSO due to the falsely over-penalized focused images. This is achieved by subtracting the focused image associated with the calculated data from the unfocused image associated with the observed data in the image-domain misfit function. The numerical results of the Marmousi model show that image-domain FWI is less sensitive the initial model than the conventional FWI. © 2013 SEG.

  20. Image-domain full waveform inversion

    KAUST Repository

    Zhang, Sanzong; Schuster, Gerard T.

    2013-01-01

    The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is because the waveform misfit function is highly nonlinear with respect to changes in velocity model. To reduce this nonlinearity, we define the image-domain objective function to minimize the difference of the suboffset-domain common image gathers (CIGs) obtained by migrating the observed data and the calculated data. The derivation shows that the gradient of this new objective function is the combination of the gradient of the conventional FWI and the image-domain differential semblance optimization (DSO). Compared to the conventional FWI, the imagedomain FWI is immune to cycle skipping problems by smearing the nonzero suboffset images along wavepath. It also can avoid the edge effects and the gradient artifacts that are inherent in DSO due to the falsely over-penalized focused images. This is achieved by subtracting the focused image associated with the calculated data from the unfocused image associated with the observed data in the image-domain misfit function. The numerical results of the Marmousi model show that image-domain FWI is less sensitive the initial model than the conventional FWI. © 2013 SEG.

  1. Full-waveform data for building roof step edge localization

    Science.gov (United States)

    Słota, Małgorzata

    2015-08-01

    Airborne laser scanning data perfectly represent flat or gently sloped areas; to date, however, accurate breakline detection is the main drawback of this technique. This issue becomes particularly important in the case of modeling buildings, where accuracy higher than the footprint size is often required. This article covers several issues related to full-waveform data registered on building step edges. First, the full-waveform data simulator was developed and presented in this paper. Second, this article provides a full description of the changes in echo amplitude, echo width and returned power caused by the presence of edges within the laser footprint. Additionally, two important properties of step edge echoes, peak shift and echo asymmetry, were noted and described. It was shown that these properties lead to incorrect echo positioning along the laser center line and can significantly reduce the edge points' accuracy. For these reasons and because all points are aligned with the center of the beam, regardless of the actual target position within the beam footprint, we can state that step edge points require geometric corrections. This article presents a novel algorithm for the refinement of step edge points. The main distinguishing advantage of the developed algorithm is the fact that none of the additional data, such as emitted signal parameters, beam divergence, approximate edge geometry or scanning settings, are required. The proposed algorithm works only on georeferenced profiles of reflected laser energy. Another major advantage is the simplicity of the calculation, allowing for very efficient data processing. Additionally, the developed method of point correction allows for the accurate determination of points lying on edges and edge point densification. For this reason, fully automatic localization of building roof step edges based on LiDAR full-waveform data with higher accuracy than the size of the lidar footprint is feasible.

  2. Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms

    Science.gov (United States)

    Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng

    2013-04-01

    Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.

  3. Approaches to Mixed Methods Dissemination and Implementation Research: Methods, Strengths, Caveats, and Opportunities.

    Science.gov (United States)

    Green, Carla A; Duan, Naihua; Gibbons, Robert D; Hoagwood, Kimberly E; Palinkas, Lawrence A; Wisdom, Jennifer P

    2015-09-01

    Limited translation of research into practice has prompted study of diffusion and implementation, and development of effective methods of encouraging adoption, dissemination and implementation. Mixed methods techniques offer approaches for assessing and addressing processes affecting implementation of evidence-based interventions. We describe common mixed methods approaches used in dissemination and implementation research, discuss strengths and limitations of mixed methods approaches to data collection, and suggest promising methods not yet widely used in implementation research. We review qualitative, quantitative, and hybrid approaches to mixed methods dissemination and implementation studies, and describe methods for integrating multiple methods to increase depth of understanding while improving reliability and validity of findings.

  4. Teaching Psychological Research Methods through a Pragmatic and Programmatic Approach

    Science.gov (United States)

    Rosenkranz, Patrick; Fielden, Amy; Tzemou, Effy

    2014-01-01

    Research methods teaching in psychology is pivotal in preparing students for the transition from student as learner to independent practitioner. We took an action research approach to re-design, implement and evaluate a module guiding students through a programmatic and pragmatic research cycle. These revisions allow students to experience how…

  5. Research on Language Learning Strategies: Methods, Findings, and Instructional Issues.

    Science.gov (United States)

    Oxford, Rebecca; Crookall, David

    1989-01-01

    Surveys research on formal and informal second-language learning strategies, covering the effectiveness of research methods involving making lists, interviews and thinking aloud, note-taking, diaries, surveys, and training. Suggestions for future and improved research are presented. (131 references) (CB)

  6. Rhetorical Structure of Education Research Article Methods Sections

    Science.gov (United States)

    Zhang, Baoya; Wannaruk, Anchalee

    2016-01-01

    This study investigated the rhetorical move structure of the education research article genre within the framework of Swales' (1981, 1990, 2004) move analysis. A corpus of 120 systematically sampled empirical education research articles served as data input for the analysis. The results indicate that the education research article methods section…

  7. Research and development of radioactive waste treatment methods

    International Nuclear Information System (INIS)

    Nguyen Thi Nang

    2000-01-01

    The Nuclear Research Institute (NRI) uses the reactor for research, training, isotope production and activation analyses. NRI generates about 150 m 3 of liquid and 5 m 3 of solid wastes every year. The researched methods applied to treatment of radwastes are coagulation-precipitation and two steps ion-exchange for liquid waste and compaction for solid waste are described. (author)

  8. Mixed Methods Research: What Are the Key Issues to Consider?

    Science.gov (United States)

    Ghosh, Rajashi

    2016-01-01

    Mixed methods research (MMR) is increasingly becoming a popular methodological approach in several fields due to the promise it holds for comprehensive understanding of complex problems being researched. However, researchers interested in MMR often lack reference to a guide that can explain the key issues pertaining to the paradigm wars…

  9. Towards Multi-Method Research Approach in Empirical Software Engineering

    Science.gov (United States)

    Mandić, Vladimir; Markkula, Jouni; Oivo, Markku

    This paper presents results of a literature analysis on Empirical Research Approaches in Software Engineering (SE). The analysis explores reasons why traditional methods, such as statistical hypothesis testing and experiment replication are weakly utilized in the field of SE. It appears that basic assumptions and preconditions of the traditional methods are contradicting the actual situation in the SE. Furthermore, we have identified main issues that should be considered by the researcher when selecting the research approach. In virtue of reasons for weak utilization of traditional methods we propose stronger use of Multi-Method approach with Pragmatism as the philosophical standpoint.

  10. Inventory of research methods for librarianship and informatics.

    Science.gov (United States)

    Eldredge, Jonathan D

    2004-01-01

    This article defines and describes the rich variety of research designs found in librarianship and informatics practice. Familiarity with the range of methods and the ability to make distinctions between those specific methods can enable authors to label their research reports correctly. The author has compiled an inventory of methods from a variety of disciplines, but with attention to the relevant applications of a methodology to the field of librarianship. Each entry in the inventory includes a definition and description for the particular research method. Some entries include references to resource material and examples.

  11. Storytelling as a way for humanizing research methods

    OpenAIRE

    Grenness, Tor

    2016-01-01

    This is an Open Access journal. The article is aslo available from www.idrcentre.org This article examines how the use of storytelling can serve as a pedagogical strategy in the teaching of research methods. Research methods and statistics anxiety is fairly widespread among students in higher education. Introducing storytelling has been found to decrease this anxiety. The term “humanizing research methods” implies a focus on students’ needs that goes beyond transferring knowledge of the co...

  12. How to Construct a Mixed Methods Research Design

    OpenAIRE

    Schoonenboom, Judith; Johnson, R. Burke

    2017-01-01

    This article provides researchers with knowledge of how to design a high quality mixed methods research study. To design a mixed study, researchers must understand and carefully consider each of the dimensions of mixed methods design, and always keep an eye on the issue of validity. We explain the seven major design dimensions: purpose, theoretical drive, timing (simultaneity and dependency), point of integration, typological versus interactive design approaches, planned versus emergent desig...

  13. Time stepping free numerical solution of linear differential equations: Krylov subspace versus waveform relaxation

    NARCIS (Netherlands)

    Bochev, Mikhail A.; Oseledets, I.V.; Tyrtyshnikov, E.E.

    2013-01-01

    The aim of this paper is two-fold. First, we propose an efficient implementation of the continuous time waveform relaxation method based on block Krylov subspaces. Second, we compare this new implementation against Krylov subspace methods combined with the shift and invert technique.

  14. SOCIAL RESEARCH METHODS IN FEMINIST'S PERSPECTIVE: A NEW WAY IN DOING SOCIOLINGUISTIC QUALITATIVE RESEARCH

    Directory of Open Access Journals (Sweden)

    Esther Kuntjara

    2001-01-01

    Full Text Available Traditional research methods have been dominated by positivism which assumes the importance of objectivity, contextual independency, linear causality and value free research. Feminist researchers found that such methods do not suit their inquisitive needs especially in the study of women. Naturalistic research methods, however, do not only suit them but they are also able to voice women's problems. Two methods, i.e. interviewing and ethnography are discussed as to how they are commonly used by feminist researchers on many social studies on women, including the linguistic studies of gender.

  15. Using the Delphi expert consensus method in mental health research.

    Science.gov (United States)

    Jorm, Anthony F

    2015-10-01

    The article gives an introductory overview of the use of the Delphi expert consensus method in mental health research. It explains the rationale for using the method, examines the range of uses to which it has been put in mental health research, and describes the stages of carrying out a Delphi study using examples from the literature. To ascertain the range of uses, a systematic search was carried out in PubMed. The article also examines the implications of 'wisdom of crowds' research for how to conduct Delphi studies. The Delphi method is a systematic way of determining expert consensus that is useful for answering questions that are not amenable to experimental and epidemiological methods. The validity of the approach is supported by 'wisdom of crowds' research showing that groups can make good judgements under certain conditions. In mental health research, the Delphi method has been used for making estimations where there is incomplete evidence (e.g. What is the global prevalence of dementia?), making predictions (e.g. What types of interactions with a person who is suicidal will reduce their chance of suicide?), determining collective values (e.g. What areas of research should be given greatest priority?) and defining foundational concepts (e.g. How should we define 'relapse'?). A range of experts have been used in Delphi research, including clinicians, researchers, consumers and caregivers. The Delphi method has a wide range of potential uses in mental health research. © The Royal Australian and New Zealand College of Psychiatrists 2015.

  16. Participatory methods in pediatric participatory research: a systematic review.

    Science.gov (United States)

    Haijes, Hanneke A; van Thiel, Ghislaine J M W

    2016-05-01

    Meaningful child participation in medical research is seen as important. In order to facilitate further development of participatory research, we performed a systematic literature study to describe and assess the available knowledge on participatory methods in pediatric research. A search was executed in five databases: PubMed, CINAHL, PsycINFO, Scopus, and Cochrane. After careful screening of relevant papers, finally 24 documents were included in our analysis. Literature on participatory methods in pediatric research appears generally to be descriptive, whereby high-quality evidence is lacking. Overall, five groups of participatory methods for children could be distinguished: observational, verbal, written, visual, and active methods. The choice for one of these methods should be based on the child's age, on social and demographic characteristics, and on the research objectives. To date, these methods are still solely used for obtaining data, yet they are suitable for conducting meaningful participation. This may result in a successful partnership between children and researchers. Researchers conducting participatory research with children can use this systematic review in order to weigh the current knowledge about the participatory methods presented.

  17. 10 best resources on ... mixed methods research in health systems.

    Science.gov (United States)

    Ozawa, Sachiko; Pongpirul, Krit

    2014-05-01

    Mixed methods research has become increasingly popular in health systems. Qualitative approaches are often used to explain quantitative results and help to develop interventions or survey instruments. Mixed methods research is especially important in low- and middle-income country (LMIC) settings, where understanding social, economic and cultural contexts are essential to assess health systems performance. To provide researchers and programme managers with a guide to mixed methods research in health systems, we review the best resources with a focus on LMICs. We selected 10 best resources (eight peer-reviewed articles and two textbooks) based on their importance and frequency of use (number of citations), comprehensiveness of content, usefulness to readers and relevance to health systems research in resource-limited contexts. We start with an overview on mixed methods research and discuss resources that are useful for a better understanding of the design and conduct of mixed methods research. To illustrate its practical applications, we provide examples from various countries (China, Vietnam, Kenya, Tanzania, Zambia and India) across different health topics (tuberculosis, malaria, HIV testing and healthcare costs). We conclude with some toolkits which suggest what to do when mixed methods findings conflict and provide guidelines for evaluating the quality of mixed methods research.

  18. Autoethnography as a research method: Advantages, limitations and criticisms

    Directory of Open Access Journals (Sweden)

    Mariza G. Méndez

    2014-01-01

    Full Text Available The aim of this article is to review the literature  on autoethnography as a research method. It will first describe what is meant by autoethnography, or evocative narratives, and consider the particular features of this type of method. The paper will go on to explore the advantages, limitations and criticisms this research method has endured since its emergence during the 1980s. Finally, the different approaches to the evaluation of autoethnography will be reviewed.

  19. [Application and Integration of Qualitative and Quantitative Research Methods in Intervention Studies in Rehabilitation Research].

    Science.gov (United States)

    Wirtz, M A; Strohmer, J

    2016-06-01

    In order to develop and evaluate interventions in rehabilitation research a wide range of empirical research methods may be adopted. Qualitative research methods emphasize the relevance of an open research focus and a natural proximity to research objects. Accordingly, using qualitative methods special benefits may arise if researchers strive to identify and organize unknown information aspects (inductive purpose). Particularly, quantitative research methods require a high degree of standardization and transparency of the research process. Furthermore, a clear definition of efficacy and effectiveness exists (deductive purpose). These paradigmatic approaches are characterized by almost opposite key characteristics, application standards, purposes and quality criteria. Hence, specific aspects have to be regarded if researchers aim to select or combine those approaches in order to ensure an optimal gain in knowledge. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Individual Biometric Identification Using Multi-Cycle Electrocardiographic Waveform Patterns

    Directory of Open Access Journals (Sweden)

    Wonki Lee

    2018-03-01

    Full Text Available The electrocardiogram (ECG waveform conveys information regarding the electrical property of the heart. The patterns vary depending on the individual heart characteristics. ECG features can be potentially used for biometric recognition. This study presents a new method using the entire ECG waveform pattern for matching and demonstrates that the approach can potentially be employed for individual biometric identification. Multi-cycle ECG signals were assessed using an ECG measuring circuit, and three electrodes can be patched on the wrists or fingers for considering various measurements. For biometric identification, our-fold cross validation was used in the experiments for assessing how the results of a statistical analysis will generalize to an independent data set. Four different pattern matching algorithms, i.e., cosine similarity, cross correlation, city block distance, and Euclidean distances, were tested to compare the individual identification performances with a single channel of ECG signal (3-wire ECG. To evaluate the pattern matching for biometric identification, the ECG recordings for each subject were partitioned into training and test set. The suggested method obtained a maximum performance of 89.9% accuracy with two heartbeats of ECG signals measured on the wrist and 93.3% accuracy with three heartbeats for 55 subjects. The performance rate with ECG signals measured on the fingers improved up to 99.3% with two heartbeats and 100% with three heartbeats of signals for 20 subjects.

  1. Individual Biometric Identification Using Multi-Cycle Electrocardiographic Waveform Patterns.

    Science.gov (United States)

    Lee, Wonki; Kim, Seulgee; Kim, Daeeun

    2018-03-28

    The electrocardiogram (ECG) waveform conveys information regarding the electrical property of the heart. The patterns vary depending on the individual heart characteristics. ECG features can be potentially used for biometric recognition. This study presents a new method using the entire ECG waveform pattern for matching and demonstrates that the approach can potentially be employed for individual biometric identification. Multi-cycle ECG signals were assessed using an ECG measuring circuit, and three electrodes can be patched on the wrists or fingers for considering various measurements. For biometric identification, our-fold cross validation was used in the experiments for assessing how the results of a statistical analysis will generalize to an independent data set. Four different pattern matching algorithms, i.e., cosine similarity, cross correlation, city block distance, and Euclidean distances, were tested to compare the individual identification performances with a single channel of ECG signal (3-wire ECG). To evaluate the pattern matching for biometric identification, the ECG recordings for each subject were partitioned into training and test set. The suggested method obtained a maximum performance of 89.9% accuracy with two heartbeats of ECG signals measured on the wrist and 93.3% accuracy with three heartbeats for 55 subjects. The performance rate with ECG signals measured on the fingers improved up to 99.3% with two heartbeats and 100% with three heartbeats of signals for 20 subjects.

  2. [Mixed methods research in public health: issues and illustration].

    Science.gov (United States)

    Guével, Marie-Renée; Pommier, Jeanine

    2012-01-01

    For many years, researchers in a range of fields have combined quantitative and qualitative methods. However, the combined use of quantitative and qualitative methods has only recently been conceptualized and defined as mixed methods research. Some authors have described the emerging field as a third methodological tradition (in addition to the qualitative and quantitative traditions). Mixed methods research combines different perspectives and facilitates the study of complex interventions or programs, particularly in public health, an area where interdisciplinarity is critical. However, the existing literature is primarily in English. By contrast, the literature in French remains limited. The purpose of this paper is to present the emergence of mixed methods research for francophone public health specialists. A literature review was conducted to identify the main characteristics of mixed methods research. The results provide an overall picture of the mixed methods approach through its history, definitions, and applications, and highlight the tools developed to clarify the approach (typologies) and to implement it (integration of results and quality standards). The tools highlighted in the literature review are illustrated by a study conducted in France. Mixed methods research opens new possibilities for examining complex research questions and provides relevant and promising opportunities for addressing current public health issues in France.

  3. Focus Group Interview in Family Practice Research: Implementing a qualitative research method

    OpenAIRE

    Wood, Marjorie L.

    1992-01-01

    Focus group interviews, described as a qualitative research method with good potential in family medicine, are traced from their origins in market research to their growing role in sociology and medicine. Features of this method are described, including design, conduct, and analysis. Both proven and potential areas for primary care research using focus groups are outlined.

  4. Contextual and Analytic Qualities of Research Methods Exemplified in Research on Teaching

    Science.gov (United States)

    Svensson, Lennart; Doumas, Kyriaki

    2013-01-01

    The aim of the present article is to discuss contextual and analytic qualities of research methods. The arguments are specified in relation to research on teaching. A specific investigation is used as an example to illustrate the general methodological approach. It is argued that research methods should be carefully grounded in an understanding of…

  5. Writing a Mixed Methods Report in Social Work Research

    Science.gov (United States)

    Bronstein, Laura R.; Kovacs, Pamela J.

    2013-01-01

    This article briefly chronicles the development of mixed methods research and its use in social work. We then move onto a discussion of terms and designs, reasons for (and for not) using mixed methods. Drawing upon exemplars, we address how to write up a mixed methods study when (1) the sample is single; single for one part, with a subset for the…

  6. Neutron spectrometric methods for core inventory verification in research reactors

    International Nuclear Information System (INIS)

    Ellinger, A.; Filges, U.; Hansen, W.; Knorr, J.; Schneider, R.

    2002-01-01

    In consequence of the Non-Proliferation Treaty safeguards, inspections are periodically made in nuclear facilities by the IAEA and the EURATOM Safeguards Directorate. The inspection methods are permanently improved. Therefore, the Core Inventory Verification method is being developed as an indirect method for the verification of the core inventory and to check the declared operation of research reactors

  7. Research on psychological evaluation method for nuclear power plant operators

    International Nuclear Information System (INIS)

    Fang Xiang; He Xuhong; Zhao Bingquan

    2007-01-01

    The qualitative and quantitative psychology evaluation methods to the nuclear power plant operators were analyzed and discussed in the paper. The comparison analysis to the scope and result of application was carried out between method of outline figure fitted and method of fuzzy synthetic evaluation. The research results can be referenced to the evaluation of nuclear power plant operators. (authors)

  8. Fast evolution and waveform generator for extreme-mass-ratio inspirals in equatorial-circular orbits

    International Nuclear Information System (INIS)

    Han, Wen-Biao

    2016-01-01

    In this paper we discuss the development of a fast and accurate waveform model for the quasi-circular orbital evolution of extreme-mass-ratio inspirals (EMRIs). This model simply employs the data of a few numerical Teukoulsky-based energy fluxes and waveforms to fit out a set of polynomials for the entire fluxes and waveforms. These obtained polynomials are accurate enough in the entire evolution domain, and much more accurate than the resummation post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a black hole becomes large. The dynamical equation we adopted for orbital revolution is the effective-one-body (EOB) formalism. Because of the simplified expressions, the efficiency of calculating the orbital evolution with our polynomials is also better than the traditional method which uses the resummed PN analytical fluxes. Our model should be useful in calculations of waveform templates of EMRIs for gravitational wave (GW) detectors such as the evolved Laser Interferometer Space Antenna (eLISA). (paper)

  9. Doppler waveforms of the hepatic veins in children with diffuse fatty infiltration of the liver

    International Nuclear Information System (INIS)

    Uzun, Hakan; Yazici, Burhan; Erdogmus, Besir; Kocabay, Kenan; Buyukkaya, Ramazan; Buyukkaya, Ayla; Yazgan, Omer

    2009-01-01

    Objective: The aim of this study was to investigate the effect of fatty infiltration of the liver (FIL) on the Doppler waveform pattern in the hepatic veins of obese children. Methods: In this prospective study, 59 patients with diffuse FIL and 45 normal healthy children who served as control group underwent hepatic vein B-mod and duplex Doppler sonography. The Doppler sonography spectrum of the right hepatic vein was classified into three groups: triphasic waveform, biphasic waveform, and monophasic or flat waveform. Results: There was a statistically significant difference in the phasicity of hepatic venous flow between patients and control subjects (p < 0.001). The Doppler flow pattern in the right hepatic vein was triphasic in 28 (47.5%), biphasic in 28 (47.5%), and monophasic in 3 (5%) children with fatty liver, while it was triphasic in 43 (95.6%) and biphasic in 2 (4.4%) control subjects. There was an inverse correlation between the sonographic grade of fatty infiltration of the liver and the phasicity of hepatic venous flow (r = -0.479, p < 0.001). Conclusions: Abnormal right hepatic vein Doppler waveform, biphasic as well as monophasic, can be seen in healthy obese children with diffuse FIL.

  10. Codesign of Beam Pattern and Sparse Frequency Waveforms for MIMO Radar

    Directory of Open Access Journals (Sweden)

    Chaoyun Mai

    2015-01-01

    Full Text Available Multiple-input multiple-output (MIMO radar takes the advantages of high degrees of freedom for beam pattern design and waveform optimization, because each antenna in centralized MIMO radar system can transmit different signal waveforms. When continuous band is divided into several pieces, sparse frequency radar waveforms play an important role due to the special pattern of the sparse spectrum. In this paper, we start from the covariance matrix of the transmitted waveform and extend the concept of sparse frequency design to the study of MIMO radar beam pattern. With this idea in mind, we first solve the problem of semidefinite constraint by optimization tools and get the desired covariance matrix of the ideal beam pattern. Then, we use the acquired covariance matrix and generalize the objective function by adding the constraint of both constant modulus of the signals and corresponding spectrum. Finally, we solve the objective function by the cyclic algorithm and obtain the sparse frequency MIMO radar waveforms with desired beam pattern. The simulation results verify the effectiveness of this method.

  11. Qualitative methods in radiography research: a proposed framework

    International Nuclear Information System (INIS)

    Adams, J.; Smith, T.

    2003-01-01

    Introduction: While radiography is currently developing a research base, which is important in terms of professional development and informing practice and policy issues in the field, the amount of research published by radiographers remains limited. However, a range of qualitative methods offer further opportunities for radiography research. Purpose: This paper briefly introduces a number of key qualitative methods (qualitative interviews, focus groups, observational methods, diary methods and document/text analysis) and sketches one possible framework for future qualitative work in radiography research. The framework focuses upon three areas for study: intra-professional issues; inter-professional issues; and clinical practice, patient and health delivery issues. While the paper outlines broad areas for future focus rather than providing a detailed protocol for how individual pieces of research should be conducted, a few research questions have been chosen and examples of possible qualitative methods required to answer such questions are outlined for each area. Conclusion: Given the challenges and opportunities currently facing the development of a research base within radiography, the outline of key qualitative methods and broad areas suitable for their application is offered as a useful tool for those within the profession looking to embark upon or enhance their research career

  12. Mixed methods research - the best of both worlds?

    Science.gov (United States)

    van Griensven, Hubert; Moore, Ann P; Hall, Valerie

    2014-10-01

    There has been a bias towards quantitative research approaches within manual therapy, which may have resulted in a narrow understanding of manual therapy practice. The aim of this Masterclass is to make a contribution to the expansion of methodologies used in manual therapy enquiry by discussing mixed methods research (MMR), a methodology which utilises both qualitative and quantitative methods within a single study in order to provide more comprehensive insights. To review rationales for MMR, as well as some of the common design options and potential difficulties. The paper also discusses theoretical frameworks that have been used to underpin qualitative and quantitative research, and ongoing debates about the possibility of combining them. Complexities associated with health and manual therapy cannot always be investigated satisfactorily by using a single research method. Some issues require a more comprehensive understanding, which may be provided by combining the strengths of quantitative and qualitative methods in a mixed methods study. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Improving the Development of Student's Research Questions and Hypotheses in an Introductory Business Research Methods Course

    Science.gov (United States)

    Strangman, Lauria; Knowles, Elizabeth

    2012-01-01

    In an introductory research methods course, students often develop research questions and hypotheses that are vague or confusing, do not contain measurable concepts, and are too narrow in scope or vision. Because of this, the final research projects often fail to provide useful information or address the overall research problem. A Lesson Study…

  14. Doing Mixed Methods Research Pragmatically: Implications for the Rediscovery of Pragmatism as a Research Paradigm

    Science.gov (United States)

    Feilzer, Martina Yvonne

    2010-01-01

    This article explores the practical relevance of pragmatism as a research paradigm through the example of a piece of pragmatic research that not only used both quantitative and qualitative research methods but also exploited the inherent duality of the data analyzed. Thus, the article aims to make the case that pragmatism as a research paradigm…

  15. Creating and supporting a mixed methods health services research team.

    Science.gov (United States)

    Bowers, Barbara; Cohen, Lauren W; Elliot, Amy E; Grabowski, David C; Fishman, Nancy W; Sharkey, Siobhan S; Zimmerman, Sheryl; Horn, Susan D; Kemper, Peter

    2013-12-01

    To use the experience from a health services research evaluation to provide guidance in team development for mixed methods research. The Research Initiative Valuing Eldercare (THRIVE) team was organized by the Robert Wood Johnson Foundation to evaluate The Green House nursing home culture change program. This article describes the development of the research team and provides insights into how funders might engage with mixed methods research teams to maximize the value of the team. Like many mixed methods collaborations, the THRIVE team consisted of researchers from diverse disciplines, embracing diverse methodologies, and operating under a framework of nonhierarchical, shared leadership that required new collaborations, engagement, and commitment in the context of finite resources. Strategies to overcome these potential obstacles and achieve success included implementation of a Coordinating Center, dedicated time for planning and collaborating across researchers and methodologies, funded support for in-person meetings, and creative optimization of resources. Challenges are inevitably present in the formation and operation of effective mixed methods research teams. However, funders and research teams can implement strategies to promote success. © Health Research and Educational Trust.

  16. A CTSA Agenda to Advance Methods for Comparative Effectiveness Research

    Science.gov (United States)

    Helfand, Mark; Tunis, Sean; Whitlock, Evelyn P.; Pauker, Stephen G.; Basu, Anirban; Chilingerian, Jon; Harrell Jr., Frank E.; Meltzer, David O.; Montori, Victor M.; Shepard, Donald S.; Kent, David M.

    2011-01-01

    Abstract Clinical research needs to be more useful to patients, clinicians, and other decision makers. To meet this need, more research should focus on patient‐centered outcomes, compare viable alternatives, and be responsive to individual patients’ preferences, needs, pathobiology, settings, and values. These features, which make comparative effectiveness research (CER) fundamentally patient‐centered, challenge researchers to adopt or develop methods that improve the timeliness, relevance, and practical application of clinical studies. In this paper, we describe 10 priority areas that address 3 critical needs for research on patient‐centered outcomes (PCOR): (1) developing and testing trustworthy methods to identify and prioritize important questions for research; (2) improving the design, conduct, and analysis of clinical research studies; and (3) linking the process and outcomes of actual practice to priorities for research on patient‐centered outcomes. We argue that the National Institutes of Health, through its clinical and translational research program, should accelerate the development and refinement of methods for CER by linking a program of methods research to the broader portfolio of large, prospective clinical and health system studies it supports. Insights generated by this work should be of enormous value to PCORI and to the broad range of organizations that will be funding and implementing CER. Clin Trans Sci 2011; Volume 4: 188–198 PMID:21707950

  17. Continuous-waveform constant-current isolated physiological stimulator

    Science.gov (United States)

    Holcomb, Mark R.; Devine, Jack M.; Harder, Rene; Sidorov, Veniamin Y.

    2012-04-01

    We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.

  18. Assessment of change in knowledge about research methods among delegates attending research methodology workshop

    Directory of Open Access Journals (Sweden)

    Manisha Shrivastava

    2018-01-01

    Conclusion: There was increase in knowledge of the delegates after attending research methodology workshops. Participatory research methodology workshops are good methods of imparting knowledge, also the long term effects needs to be evaluated.

  19. More than Method?: A Discussion of Paradigm Differences within Mixed Methods Research

    Science.gov (United States)

    Harrits, Gitte Sommer

    2011-01-01

    This article challenges the idea that mixed methods research (MMR) constitutes a coherent research paradigm and explores how different research paradigms exist within MMR. Tracing paradigmatic differences at the level of methods, ontology, and epistemology, two MMR strategies are discussed: nested analysis, recently presented by the American…

  20. Direct closed-form covariance matrix and finite alphabet constant-envelope waveforms for planar array beampatterns

    KAUST Repository

    Ahmed, Sajid

    2016-11-24

    Various examples of methods and systems are provided for direct closed-form finite alphabet constant-envelope waveforms for planar array beampatterns. In one example, a method includes defining a waveform covariance matrix based at least in part upon a two-dimensional fast Fourier transform (2D-FFT) analysis of a frequency domain matrix Hf associated with a planar array of antennas. Symbols can be encoded based upon the waveform covariance matrix and the encoded symbols can be transmitted via the planar array of antennas. In another embodiment, a system comprises an N x M planar array of antennas and transmission circuitry configured to transmit symbols via a two-dimensional waveform beampattern defined based at least in part upon a 2D-FFT analysis of a frequency domain matrix Hf associated with the planar array of antennas.

  1. Correlation between the respiratory waveform measured using a respiratory sensor and 3D tumor motion in gated radiotherapy

    International Nuclear Information System (INIS)

    Tsunashima, Yoshikazu; Sakae, Takeji; Shioyama, Yoshiyuki; Kagei, Kenji; Terunuma, Toshiyuki; Nohtomi, Akihiro; Akine, Yasuyuki

    2004-01-01

    Purpose: The purpose of this study is to investigate the correlation between the respiratory waveform measured using a respiratory sensor and three-dimensional (3D) tumor motion. Methods and materials: A laser displacement sensor (LDS: KEYENCE LB-300) that measures distance using infrared light was used as the respiratory sensor. This was placed such that the focus was in an area around the patient's navel. When the distance from the LDS to the body surface changes as the patient breathes, the displacement is detected as a respiratory waveform. To obtain the 3D tumor motion, a biplane digital radiography unit was used. For the tumor in the lung, liver, and esophagus of 26 patients, the waveform was compared with the 3D tumor motion. The relationship between the respiratory waveform and the 3D tumor motion was analyzed by means of the Fourier transform and a cross-correlation function. Results: The respiratory waveform cycle agreed with that of the cranial-caudal and dorsal-ventral tumor motion. A phase shift observed between the respiratory waveform and the 3D tumor motion was principally in the range 0.0 to 0.3 s, regardless of the organ being measured, which means that the respiratory waveform does not always express the 3D tumor motion with fidelity. For this reason, the standard deviation of the tumor position in the expiration phase, as indicated by the respiratory waveform, was derived, which should be helpful in suggesting the internal margin required in the case of respiratory gated radiotherapy. Conclusion: Although obtained from only a few breathing cycles for each patient, the correlation between the respiratory waveform and the 3D tumor motion was evident in this study. If this relationship is analyzed carefully and an internal margin is applied, the accuracy and convenience of respiratory gated radiotherapy could be improved by use of the respiratory sensor.Thus, it is expected that this procedure will come into wider use

  2. Linking aims, paradigm and method in nursing research.

    Science.gov (United States)

    Houghton, Catherine; Hunter, Andrew; Meskell, Pauline

    2012-01-01

    To explore the use of paradigms as ontological and philosophical guides for conducting PhD research. A paradigm can help to bridge the aims of a study and the methods to achieve them. However, choosing a paradigm can be challenging for doctoral researchers: there can be ambiguity about which paradigm is suitable for a particular research question and there is a lack of guidance on how to shape the research process for a chosen paradigm. The authors discuss three paradigms used in PhD nursing research: post-positivism, interpretivism and pragmatism. They compare each paradigm in relation to its ontology, epistemology and methodology, and present three examples of PhD nursing research studies to illustrate how research can be conducted using these paradigms in the context of the research aims and methods. The commonalities and differences between the paradigms and their uses are highlighted. Creativity and flexibility are important when deciding on a paradigm. However, consistency and transparency are also needed to ensure the quality and rigour necessary for conducting nursing research. When choosing a suitable paradigm, the researcher should ensure that the ontology, epistemology and methodology of the paradigm are manifest in the methods and research strategies employed.

  3. Methods That Matter: Integrating Mixed Methods for More Effective Social Science Research

    Science.gov (United States)

    Hay, M. Cameron, Ed.

    2016-01-01

    To do research that really makes a difference--the authors of this book argue--social scientists need questions and methods that reflect the complexity of the world. Bringing together a consortium of voices across a variety of fields, "Methods that Matter" offers compelling and successful examples of mixed methods research that do just…

  4. Mixed Methods in Biomedical and Health Services Research

    OpenAIRE

    Curry, Leslie A.; Krumholz, Harlan M.; O’Cathain, Alicia; Plano Clark, Vicki L.; Cherlin, Emily; Bradley, Elizabeth H.

    2013-01-01

    Mixed methods studies, in which qualitative and quantitative methods are combined in a single program of inquiry, can be valuable in biomedical and health services research, where the complementary strengths of each approach can yield greater insight into complex phenomena than either approach alone. Although interest in mixed methods is growing among science funders and investigators, written guidance on how to conduct and assess rigorous mixed methods studies is not readily accessible to th...

  5. Waveform shape analysis: extraction of physiologically relevant information from Doppler recordings.

    Science.gov (United States)

    Ramsay, M M; Broughton Pipkin, F; Rubin, P C; Skidmore, R

    1994-05-01

    1. Doppler recordings were made from the brachial artery of healthy female subjects during a series of manoeuvres which altered the pressure-flow characteristics of the vessel. 2. Changes were induced in the peripheral circulation of the forearm by the application of heat or ice-packs. A sphygmomanometer cuff was used to create graded occlusion of the vessel above and below the point of measurement. Recordings were also made whilst the subjects performed a standardized Valsalva manoeuvre. 3. The Doppler recordings were analysed both with the standard waveform indices (systolic/diastolic ratio, pulsatility index and resistance index) and by the method of Laplace transform analysis. 4. The waveform parameters obtained by Laplace transform analysis distinguished the different changes in flow conditions; they thus had direct physiological relevance, unlike the standard waveform indices.

  6. Elastic reflection based waveform inversion with a nonlinear approach

    KAUST Repository

    Guo, Qiang; Alkhalifah, Tariq Ali

    2017-01-01

    Full waveform inversion (FWI) is a highly nonlinear problem due to the complex reflectivity of the Earth, and this nonlinearity only increases under the more expensive elastic assumption. In elastic media, we need a good initial P-wave velocity and even a better initial S-wave velocity models with accurate representation of the low model wavenumbers for FWI to converge. However, inverting for the low wavenumber components of P- and S-wave velocities using reflection waveform inversion (RWI) with an objective to fit the reflection shape, rather than produce reflections, may mitigate the limitations of FWI. Because FWI, performing as a migration operator, is in preference of the high wavenumber updates along reflectors. We propose a nonlinear elastic RWI that inverts for both the low wavenumber and perturbation components of the P- and S-wave velocities. To generate the full elastic reflection wavefields, we derive an equivalent stress source made up by the inverted model perturbations and incident wavefields. We update both the perturbation and propagation parts of the velocity models in a nested fashion. Applications on synthetic isotropic models and field data show that our method can efficiently update the low and high wavenumber parts of the models.

  7. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints

    Science.gov (United States)

    Zhang, Zhen-dong; Alkhalifah, Tariq; Naeini, Ehsan Zabihi; Sun, Bingbing

    2018-03-01

    Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like in reservoir delineation, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Some anisotropic parameters are insufficiently updated because of their minor contributions to the surface collected data. Adding rock physics constraints to the inversion helps mitigate such limited sensitivity, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a global constraint for the whole area. Since similar rock formations inside the Earth admit consistent elastic properties and relative values of elasticity and anisotropy parameters (this enables us to define them as a seismic facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel approach to use facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such facies using Bayesian theory and update them at each iteration of the inversion using both the inverted models and a prior information. We take the uncertainties of the estimated parameters (approximated by radiation patterns) into consideration and improve the quality of estimated facies maps. Four numerical examples corresponding to different acquisition, physical assumptions and model circumstances are used to verify the effectiveness of the proposed method.

  8. Elastic reflection based waveform inversion with a nonlinear approach

    KAUST Repository

    Guo, Qiang

    2017-08-16

    Full waveform inversion (FWI) is a highly nonlinear problem due to the complex reflectivity of the Earth, and this nonlinearity only increases under the more expensive elastic assumption. In elastic media, we need a good initial P-wave velocity and even a better initial S-wave velocity models with accurate representation of the low model wavenumbers for FWI to converge. However, inverting for the low wavenumber components of P- and S-wave velocities using reflection waveform inversion (RWI) with an objective to fit the reflection shape, rather than produce reflections, may mitigate the limitations of FWI. Because FWI, performing as a migration operator, is in preference of the high wavenumber updates along reflectors. We propose a nonlinear elastic RWI that inverts for both the low wavenumber and perturbation components of the P- and S-wave velocities. To generate the full elastic reflection wavefields, we derive an equivalent stress source made up by the inverted model perturbations and incident wavefields. We update both the perturbation and propagation parts of the velocity models in a nested fashion. Applications on synthetic isotropic models and field data show that our method can efficiently update the low and high wavenumber parts of the models.

  9. Multiparameter Elastic Full Waveform Inversion With Facies Constraints

    KAUST Repository

    Zhang, Zhendong

    2017-08-17

    Full waveform inversion (FWI) aims fully benefit from all the data characteristics to estimate the parameters describing the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion as a tool beyond acoustic imaging applications, for example in reservoir analysis, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Adding rock physics constraints does help to mitigate these issues, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a boundary condition for the whole area. Since certain rock formations inside the Earth admit consistent elastic properties and relative values of elastic and anisotropic parameters (facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel confidence map based approach to utilize the facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such a confidence map using Bayesian theory, in which the confidence map is updated at each iteration of the inversion using both the inverted models and a prior information. The numerical examples show that the proposed method can reduce the trade-offs and also can improve the resolution of the inverted elastic and anisotropic properties.

  10. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints

    KAUST Repository

    Zhang, Zhendong

    2018-03-20

    Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like in reservoir delineation, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Some anisotropic parameters are insufficiently updated because of their minor contributions to the surface collected data. Adding rock physics constraints to the inversion helps mitigate such limited sensitivity, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a global constraint for the whole area. Since similar rock formations inside the Earth admit consistent elastic properties and relative values of elasticity and anisotropy parameters (this enables us to define them as a seismic facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel approach to use facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such facies using Bayesian theory and update them at each iteration of the inversion using both the inverted models and a prior information. We take the uncertainties of the estimated parameters (approximated by radiation patterns) into consideration and improve the quality of estimated facies maps. Four numerical examples corresponding to different acquisition, physical assumptions and model circumstances are used to verify the effectiveness of the proposed method.

  11. Applications of mixed-methods methodology in clinical pharmacy research.

    Science.gov (United States)

    Hadi, Muhammad Abdul; Closs, S José

    2016-06-01

    Introduction Mixed-methods methodology, as the name suggests refers to mixing of elements of both qualitative and quantitative methodologies in a single study. In the past decade, mixed-methods methodology has gained popularity among healthcare researchers as it promises to bring together the strengths of both qualitative and quantitative approaches. Methodology A number of mixed-methods designs are available in the literature and the four most commonly used designs in healthcare research are: the convergent parallel design, the embedded design, the exploratory design, and the explanatory design. Each has its own unique advantages, challenges and procedures and selection of a particular design should be guided by the research question. Guidance on designing, conducting and reporting mixed-methods research is available in the literature, so it is advisable to adhere to this to ensure methodological rigour. When to use it is best suited when the research questions require: triangulating findings from different methodologies to explain a single phenomenon; clarifying the results of one method using another method; informing the design of one method based on the findings of another method, development of a scale/questionnaire and answering different research questions within a single study. Two case studies have been presented to illustrate possible applications of mixed-methods methodology. Limitations Possessing the necessary knowledge and skills to undertake qualitative and quantitative data collection, analysis, interpretation and integration remains the biggest challenge for researchers conducting mixed-methods studies. Sequential study designs are often time consuming, being in two (or more) phases whereas concurrent study designs may require more than one data collector to collect both qualitative and quantitative data at the same time.

  12. A prospective, randomised and blinded comparison of first shock success of monophasic and biphasic waveforms in out-of-hospital cardiac arrest

    NARCIS (Netherlands)

    van Alem, Anouk P.; Chapman, Fred W.; Lank, Paula; Hart, Augustinus A. M.; Koster, Rudolph W.

    2003-01-01

    Background: Evidence suggests that biphasic waveforms are more effective than monophasic waveforms for defibrillation in out-of-hospital cardiac arrest (OHCA), yet their performance has only been compared in un-blinded studies. Methods and results: We compared the success of biphasic truncated

  13. Full-waveform inversion: From near surface to deep

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-11-01

    The ancient Persian Gulf port city of Muscat provided a spectacular setting for the SEG\\'s 2013 Workshop on Full-waveform Inversion (FWI). This active R&D topic attracted about 36 oral presentations and 20 or so posters, which added up to three intense days of ideas, images, and discussion. FWI has progressed from academic research topic to commercial workflow component in roughly 10 years, with many case studies documenting improved imaging and business value and others documenting a definite need for improved understanding of algorithms and applicability. Along with fundamental research issues of worldwide importance, the meeting provided an opportunity to showcase implications of the Middle East\\'s particular exploration challenges for the further development of FWI.

  14. Pieced Together: Collage as an Artist's Method for Interdisciplinary Research

    Directory of Open Access Journals (Sweden)

    Kathleen Vaughan

    2005-03-01

    Full Text Available As a visual artist undertaking doctoral studies in education, the author required a research method that integrated her studio practice into her research process, giving equal weight to the visual and the linguistic. Her process of finding such a method is outlined in this article, which touches on arts-based research and practice-led research, and her ultimate approach of choice, collage. Collage, a versatile art form that accommodates multiple texts and visuals in a single work, has been proposed as a model for a “borderlands epistemology”: one that values multiple distinctive understandings and that deliberately incorporates nondominant modes of knowing, such as visual arts. As such, collage is particularly suited to a feminist, postmodern, postcolonial inquiry. This article offers a preliminary theorizing of collage as a method and is illustrated with images from the author's research/visual practice.

  15. Challenges in Exploratory Methods for Tuberculosis Research in South Africa.

    Science.gov (United States)

    Macdonald, Helen; Abney, Kate; Abrams, Amber; Truyts, Carina

    2016-07-01

    Haunted by a legacy of apartheid governance that left millions in material poverty, South Africa has among the highest tuberculosis (TB) morbidity and mortality rates in the world. Our Social Markers of TB research project shared a vision of working with ethnographic research methods to understand TB-infected persons, their families, care providers, and social networks. We argue that felt and enacted TB stigma and the related HIV-TB stigma impaired our ability to collect the necessary data for a full portrait of TB-infected persons and their lived conditions. To circumvent this limitation, each researcher improvised and augmented conventional anthropological methods with more creative, directed, and at times destabilizing methods. We present three case studies as useful illustrations of the complexities and challenges we encountered in our attempts to conduct ethically sound TB research. We discuss the implications of our call for "improvisation" for the politics of research and ethical oversight. © The Author(s) 2015.

  16. Methods, measures and indicators for evaluating benefits of transportation research

    CSIR Research Space (South Africa)

    Du Plessis, Louw

    2016-04-01

    Full Text Available The purpose of this article is to provide updated information by identifying and discussing methods, measures and indicators for evaluating benefits appropriate for transportation-related research facilities/programmes. The information has been...

  17. Measuring methods, registration and signal processing for magnetic field research

    International Nuclear Information System (INIS)

    Nagiello, Z.

    1981-01-01

    Some measuring methods and signal processing systems based on analogue and digital technics, which have been applied in magnetic field research using magnetometers with ferromagnetic transducers, are presented. (author)

  18. [Baseflow separation methods in hydrological process research: a review].

    Science.gov (United States)

    Xu, Lei-Lei; Liu, Jing-Lin; Jin, Chang-Jie; Wang, An-Zhi; Guan, De-Xin; Wu, Jia-Bing; Yuan, Feng-Hui

    2011-11-01

    Baseflow separation research is regarded as one of the most important and difficult issues in hydrology and ecohydrology, but lacked of unified standards in the concepts and methods. This paper introduced the theories of baseflow separation based on the definitions of baseflow components, and analyzed the development course of different baseflow separation methods. Among the methods developed, graph separation method is simple and applicable but arbitrary, balance method accords with hydrological mechanism but is difficult in application, whereas time series separation method and isotopic method can overcome the subjective and arbitrary defects caused by graph separation method, and thus can obtain the baseflow procedure quickly and efficiently. In recent years, hydrological modeling, digital filtering, and isotopic method are the main methods used for baseflow separation.

  19. A seamless acquisition digital storage oscilloscope with three-dimensional waveform display

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kuojun, E-mail: kuojunyang@gmail.com; Guo, Lianping [School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu (China); School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore); Tian, Shulin; Zeng, Hao [School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu (China); Qiu, Lei [School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore)

    2014-04-15

    In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6 250 000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition.

  20. A seamless acquisition digital storage oscilloscope with three-dimensional waveform display

    Science.gov (United States)

    Yang, Kuojun; Tian, Shulin; Zeng, Hao; Qiu, Lei; Guo, Lianping

    2014-04-01

    In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6 250 000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition.

  1. A seamless acquisition digital storage oscilloscope with three-dimensional waveform display

    International Nuclear Information System (INIS)

    Yang, Kuojun; Guo, Lianping; Tian, Shulin; Zeng, Hao; Qiu, Lei

    2014-01-01

    In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6 250 000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition

  2. Qualitative research methods in renal medicine: an introduction.

    Science.gov (United States)

    Bristowe, Katherine; Selman, Lucy; Murtagh, Fliss E M

    2015-09-01

    Qualitative methodologies are becoming increasingly widely used in health research. However, within some specialties, including renal medicine, qualitative approaches remain under-represented in the high-impact factor journals. Qualitative research can be undertaken: (i) as a stand-alone research method, addressing specific research questions; (ii) as part of a mixed methods approach alongside quantitative approaches or (iii) embedded in clinical trials, or during the development of complex interventions. The aim of this paper is to introduce qualitative research, including the rationale for choosing qualitative approaches, and guidance for ensuring quality when undertaking and reporting qualitative research. In addition, we introduce types of qualitative data (observation, interviews and focus groups) as well as some of the most commonly encountered methodological approaches (case studies, ethnography, phenomenology, grounded theory, thematic analysis, framework analysis and content analysis). © The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  3. Rethinking a Case Study Method in Educational Research: A Comparative Analysis Method in Qualitative Research

    Science.gov (United States)

    Murakami, Yusuke

    2013-01-01

    There are two types of qualitative research that analyze a small number of cases or a single case: idiographic differentiation and nomothetic/generalization. There are few case studies of generalization. This is because theoretical inclination is weak in the field of education, and the binary framework of quantitative versus qualitative research…

  4. Advances in Statistical Methods for Substance Abuse Prevention Research

    Science.gov (United States)

    MacKinnon, David P.; Lockwood, Chondra M.

    2010-01-01

    The paper describes advances in statistical methods for prevention research with a particular focus on substance abuse prevention. Standard analysis methods are extended to the typical research designs and characteristics of the data collected in prevention research. Prevention research often includes longitudinal measurement, clustering of data in units such as schools or clinics, missing data, and categorical as well as continuous outcome variables. Statistical methods to handle these features of prevention data are outlined. Developments in mediation, moderation, and implementation analysis allow for the extraction of more detailed information from a prevention study. Advancements in the interpretation of prevention research results include more widespread calculation of effect size and statistical power, the use of confidence intervals as well as hypothesis testing, detailed causal analysis of research findings, and meta-analysis. The increased availability of statistical software has contributed greatly to the use of new methods in prevention research. It is likely that the Internet will continue to stimulate the development and application of new methods. PMID:12940467

  5. Early Cambrian wave-formed shoreline deposits

    DEFF Research Database (Denmark)

    Clemmensen, Lars B; Glad, Aslaug Clemmensen; Pedersen, Gunver Krarup

    2017-01-01

    -preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal....... During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well...

  6. Bead Collage: An Arts-Based Research Method

    Science.gov (United States)

    Kay, Lisa

    2013-01-01

    In this paper, "bead collage," an arts-based research method that invites participants to reflect, communicate and construct their experience through the manipulation of beads and found objects is explained. Emphasizing the significance of one's personal biography and experiences as a researcher, I discuss how my background as an…

  7. Book Review: Comparative Education Research: Approaches and Methods

    Directory of Open Access Journals (Sweden)

    Noel Mcginn

    2014-10-01

    Full Text Available Book Review Comparative Education Research: Approaches and Methods (2nd edition By Mark Bray, Bob Adamson and Mark Mason (Eds. (2014, 453p ISBN: 978-988-17852-8-2, Hong Kong: Comparative Education Research Centre and Springer

  8. The research methods and model of protein turnover in animal

    International Nuclear Information System (INIS)

    Wu Xilin; Yang Feng

    2002-01-01

    The author discussed the concept and research methods of protein turnover in animal body. The existing problems and the research results of animal protein turnover in recent years were presented. Meanwhile, the measures to improve the models of animal protein turnover were analyzed

  9. Credible Phenomenological Research: A Mixed-Methods Study

    Science.gov (United States)

    Flynn, Stephen V.; Korcuska, James S.

    2018-01-01

    The authors conducted a 3-phase investigation into the credible standards for phenomenological research practices identified in the literature and endorsed by a sample of counselor education qualitative research experts. Utilizing a mixed-methods approach, the findings offer evidence that professional counseling has a distinctive format in which…

  10. The Documentary Research Method – Using Documentary Sources ...

    African Journals Online (AJOL)

    Sociologists in particular and social scientists in general tend to quickly turn to social surveys to collect data for their research projects. This stems from mainstream social science research tradition that is dominated by positivist and empiricist tradition that emphasizes quantification. There is however another method of data ...

  11. Ethnographic Decision Tree Modeling: A Research Method for Counseling Psychology.

    Science.gov (United States)

    Beck, Kirk A.

    2005-01-01

    This article describes ethnographic decision tree modeling (EDTM; C. H. Gladwin, 1989) as a mixed method design appropriate for counseling psychology research. EDTM is introduced and located within a postpositivist research paradigm. Decision theory that informs EDTM is reviewed, and the 2 phases of EDTM are highlighted. The 1st phase, model…

  12. A sequential mixed methods research approach to investigating HIV ...

    African Journals Online (AJOL)

    Sequential mixed methods research is an effective approach for investigating complex problems, but it has not been extensively used in construction management research. In South Africa, the HIV/AIDS pandemic has seen construction management taking on a vital responsibility since the government called upon the ...

  13. Multidisciplinary Methods in Educational Technology Research and Development

    Science.gov (United States)

    Randolph, Justus J.

    2008-01-01

    Over the past thirty years, there has been much dialogue, and debate, about the conduct of educational technology research and development. In this brief volume, the author helps clarify that dialogue by theoretically and empirically charting the research methods used in the field and provides much practical information on how to conduct…

  14. Moving Beyond a Deficit Perspective with Qualitative Research Methods.

    Science.gov (United States)

    Anzul, Margaret; Evans, Judith F.; King, Rita; Tellier-Robinson, Dora

    2001-01-01

    Four researchers argue the merits of qualitative methodology and its particular relevance to those in special education who seek to move beyond a deficit perspective. Unconstrained by defined variables and decontextualized settings, qualitative methods allowed the researchers to extend the scope of their studies beyond originally stated research…

  15. Complexity, Methodology and Method: Crafting a Critical Process of Research

    Science.gov (United States)

    Alhadeff-Jones, Michel

    2013-01-01

    This paper defines a theoretical framework aiming to support the actions and reflections of researchers looking for a "method" in order to critically conceive the complexity of a scientific process of research. First, it starts with a brief overview of the core assumptions framing Morin's "paradigm of complexity" and Le…

  16. Standard methods for virus research in Apis mellifera

    NARCIS (Netherlands)

    Miranda, J.R.; Bailey, L.; Ball, B.V.; Blanchard, P.; Budge, G.E.; Chejanovsky, N.; Chen, Y.P.; Gauthier, L.; Genersch, E.; Graaf, de D.C.; Ribiere, M.; Ryabov, E.; Smet, de L.; Steen, van der J.J.M.

    2013-01-01

    Honey bee virus research is an enormously broad area, ranging from subcellular molecular biology through physiology and behaviour, to individual and colony-level symptoms, transmission and epidemiology. The research methods used in virology are therefore equally diverse. This article covers those

  17. Prevalence of Mixed Methods Research in Mathematics Education

    Science.gov (United States)

    Ross, Amanda A.; Onwuegbuzie, Anthony J.

    2012-01-01

    In wake of federal legislation such as the No Child Left Behind Act of 2001 that have called for "scientifically based research in education," this study examined the possible trends in mixed methods research articles published in 2 peer-reviewed mathematics education journals (n = 87) from 2002 to 2006. The study also illustrates how…

  18. Toward a Unified Validation Framework in Mixed Methods Research

    Science.gov (United States)

    Dellinger, Amy B.; Leech, Nancy L.

    2007-01-01

    The primary purpose of this article is to further discussions of validity in mixed methods research by introducing a validation framework to guide thinking about validity in this area. To justify the use of this framework, the authors discuss traditional terminology and validity criteria for quantitative and qualitative research, as well as…

  19. Deterministic operations research models and methods in linear optimization

    CERN Document Server

    Rader, David J

    2013-01-01

    Uniquely blends mathematical theory and algorithm design for understanding and modeling real-world problems Optimization modeling and algorithms are key components to problem-solving across various fields of research, from operations research and mathematics to computer science and engineering. Addressing the importance of the algorithm design process. Deterministic Operations Research focuses on the design of solution methods for both continuous and discrete linear optimization problems. The result is a clear-cut resource for understanding three cornerstones of deterministic operations resear

  20. Feasibility of waveform inversion of Rayleigh waves for shallow shear-wave velocity using a genetic algorithm

    Science.gov (United States)

    Zeng, C.; Xia, J.; Miller, R.D.; Tsoflias, G.P.

    2011-01-01

    Conventional surface wave inversion for shallow shear (S)-wave velocity relies on the generation of dispersion curves of Rayleigh waves. This constrains the method to only laterally homogeneous (or very smooth laterally heterogeneous) earth models. Waveform inversion directly fits waveforms on seismograms, hence, does not have such a limitation. Waveforms of Rayleigh waves are highly related to S-wave velocities. By inverting the waveforms of Rayleigh waves on a near-surface seismogram, shallow S-wave velocities can be estimated for earth models with strong lateral heterogeneity. We employ genetic algorithm (GA) to perform waveform inversion of Rayleigh waves for S-wave velocities. The forward problem is solved by finite-difference modeling in the time domain. The model space is updated by generating offspring models using GA. Final solutions can be found through an iterative waveform-fitting scheme. Inversions based on synthetic records show that the S-wave velocities can be recovered successfully with errors no more than 10% for several typical near-surface earth models. For layered earth models, the proposed method can generate one-dimensional S-wave velocity profiles without the knowledge of initial models. For earth models containing lateral heterogeneity in which case conventional dispersion-curve-based inversion methods are challenging, it is feasible to produce high-resolution S-wave velocity sections by GA waveform inversion with appropriate priori information. The synthetic tests indicate that the GA waveform inversion of Rayleigh waves has the great potential for shallow S-wave velocity imaging with the existence of strong lateral heterogeneity. ?? 2011 Elsevier B.V.

  1. Successful adaptation of a research methods course in South America.

    Science.gov (United States)

    Tamariz, Leonardo; Vasquez, Diego; Loor, Cecilia; Palacio, Ana

    2017-01-01

    South America has low research productivity. The lack of a structured research curriculum is one of the barriers to conducting research. To report our experience adapting an active learning-based research methods curriculum to improve research productivity at a university in Ecuador. We used a mixed-method approach to test the adaptation of the research curriculum at Universidad Catolica Santiago de Guayaquil. The curriculum uses a flipped classroom and active learning approach to teach research methods. When adapted, it was longitudinal and had 16-hour programme of in-person teaching and a six-month follow-up online component. Learners were organized in theme groups according to interest, and each group had a faculty leader. Our primary outcome was research productivity, which was measured by the succesful presentation of the research project at a national meeting, or publication in a peer-review journal. Our secondary outcomes were knowledge and perceived competence before and after course completion. We conducted qualitative interviews of faculty members and students to evaluate themes related to participation in research. Fifty university students and 10 faculty members attended the course. We had a total of 15 groups. Both knowledge and perceived competence increased by 17 and 18 percentage points, respectively. The presentation or publication rate for the entire group was 50%. The qualitative analysis showed that a lack of research culture and curriculum were common barriers to research. A US-based curriculum can be successfully adapted in low-middle income countries. A research curriculum aids in achieving pre-determined milestones. UCSG: Universidad Catolica Santiago de Guayaquil; UM: University of Miami.

  2. On the accuracy and precision of numerical waveforms: effect of waveform extraction methodology

    Science.gov (United States)

    Chu, Tony; Fong, Heather; Kumar, Prayush; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela

    2016-08-01

    We present a new set of 95 numerical relativity simulations of non-precessing binary black holes (BBHs). The simulations sample comprehensively both black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1-3. The simulations cover on average 24 inspiral orbits, plus merger and ringdown, with low initial orbital eccentricities e\\lt {10}-4. A subset of the simulations extends the coverage of non-spinning BBHs up to mass ratio q = 10. Gravitational waveforms at asymptotic infinity are computed with two independent techniques: extrapolation and Cauchy characteristic extraction. An error analysis based on noise-weighted inner products is performed. We find that numerical truncation error, error due to gravitational wave extraction, and errors due to the Fourier transformation of signals with finite length of the numerical waveforms are of similar magnitude, with gravitational wave extraction errors dominating at noise-weighted mismatches of ˜ 3× {10}-4. This set of waveforms will serve to validate and improve aligned-spin waveform models for gravitational wave science.

  3. Comparative Research: An Approach to Teaching Research Methods in Political Science and Public Administration

    Science.gov (United States)

    Engbers, Trent A

    2016-01-01

    The teaching of research methods has been at the core of public administration education for almost 30 years. But since 1990, this journal has published only two articles on the teaching of research methods. Given the increasing emphasis on data driven decision-making, greater insight is needed into the best practices for teaching public…

  4. Phenomenography and Grounded Theory as Research Methods in Computing Education Research Field

    Science.gov (United States)

    Kinnunen, Paivi; Simon, Beth

    2012-01-01

    This paper discusses two qualitative research methods, phenomenography and grounded theory. We introduce both methods' data collection and analysis processes and the type or results you may get at the end by using examples from computing education research. We highlight some of the similarities and differences between the aim, data collection and…

  5. A randomized trial comparing monophasic and biphasic waveform shocks for external cardioversion of atrial fibrillation

    NARCIS (Netherlands)

    Koster, Rudolph W.; Dorian, Paul; Chapman, Fred W.; Schmitt, Paul W.; O'Grady, Sharon G.; Walker, Robert G.

    2004-01-01

    Background We compared efficacy of and pain felt after biphasic truncated exponential (BTE) and monophasic damped sine (MDS) shocks in patients undergoing external cardioversion of atrial fibrillation (AF). Methods Patients with AF were randomized to BTE or MDS waveform cardioversion. Successive

  6. Arctic lead detection using a waveform mixture algorithm from CryoSat-2 data

    Directory of Open Access Journals (Sweden)

    S. Lee

    2018-05-01

    Full Text Available We propose a waveform mixture algorithm to detect leads from CryoSat-2 data, which is novel and different from the existing threshold-based lead detection methods. The waveform mixture algorithm adopts the concept of spectral mixture analysis, which is widely used in the field of hyperspectral image analysis. This lead detection method was evaluated with high-resolution (250 m MODIS images and showed comparable and promising performance in detecting leads when compared to the previous methods. The robustness of the proposed approach also lies in the fact that it does not require the rescaling of parameters (i.e., stack standard deviation, stack skewness, stack kurtosis, pulse peakiness, and backscatter σ0, as it directly uses L1B waveform data, unlike the existing threshold-based methods. Monthly lead fraction maps were produced by the waveform mixture algorithm, which shows interannual variability of recent sea ice cover during 2011–2016, excluding the summer season (i.e., June to September. We also compared the lead fraction maps to other lead fraction maps generated from previously published data sets, resulting in similar spatiotemporal patterns.

  7. Arctic lead detection using a waveform mixture algorithm from CryoSat-2 data

    Science.gov (United States)

    Lee, Sanggyun; Kim, Hyun-cheol; Im, Jungho

    2018-05-01

    We propose a waveform mixture algorithm to detect leads from CryoSat-2 data, which is novel and different from the existing threshold-based lead detection methods. The waveform mixture algorithm adopts the concept of spectral mixture analysis, which is widely used in the field of hyperspectral image analysis. This lead detection method was evaluated with high-resolution (250 m) MODIS images and showed comparable and promising performance in detecting leads when compared to the previous methods. The robustness of the proposed approach also lies in the fact that it does not require the rescaling of parameters (i.e., stack standard deviation, stack skewness, stack kurtosis, pulse peakiness, and backscatter σ0), as it directly uses L1B waveform data, unlike the existing threshold-based methods. Monthly lead fraction maps were produced by the waveform mixture algorithm, which shows interannual variability of recent sea ice cover during 2011-2016, excluding the summer season (i.e., June to September). We also compared the lead fraction maps to other lead fraction maps generated from previously published data sets, resulting in similar spatiotemporal patterns.

  8. Application of weighted early-arrival waveform inversion to shallow land data

    KAUST Repository

    Yu, Han; Zhang, Dongliang; Wang, Xin

    2014-01-01

    predictions and shows that the effects of noise and unpredicted amplitude variations in the inversion are reduced using this weighted early arrival waveform inversion (WEWI). We also apply this method to a 2D land data set for estimating the near

  9. Automated seismic waveform location using Multichannel Coherency Migration (MCM)-I. Theory

    Science.gov (United States)

    Shi, Peidong; Angus, Doug; Rost, Sebastian; Nowacki, Andy; Yuan, Sanyi

    2018-03-01

    With the proliferation of dense seismic networks sampling the full seismic wavefield, recorded seismic data volumes are getting bigger and automated analysis tools to locate seismic events are essential. Here, we propose a novel Multichannel Coherency Migration (MCM) method to locate earthquakes in continuous seismic data and reveal the location and origin time of seismic events directly from recorded waveforms. By continuously calculating the coherency between waveforms from different receiver pairs, MCM greatly expands the available information which can be used for event location. MCM does not require phase picking or phase identification, which allows fully automated waveform analysis. By migrating the coherency between waveforms, MCM leads to improved source energy focusing. We have tested and compared MCM to other migration-based methods in noise-free and noisy synthetic data. The tests and analysis show that MCM is noise resistant and can achieve more accurate results compared with other migration-based methods. MCM is able to suppress strong interference from other seismic sources occurring at a similar time and location. It can be used with arbitrary 3D velocity models and is able to obtain reasonable location results with smooth but inaccurate velocity models. MCM exhibits excellent location performance and can be easily parallelized giving it large potential to be developed as a real-time location method for very large datasets.

  10. Gravitational waveforms for neutron star binaries from binary black hole simulations

    Science.gov (United States)

    Barkett, Kevin; Scheel, Mark; Haas, Roland; Ott, Christian; Bernuzzi, Sebastiano; Brown, Duncan; Szilagyi, Bela; Kaplan, Jeffrey; Lippuner, Jonas; Muhlberger, Curran; Foucart, Francois; Duez, Matthew

    2016-03-01

    Gravitational waves from binary neutron star (BNS) and black-hole/neutron star (BHNS) inspirals are primary sources for detection by the Advanced Laser Interferometer Gravitational-Wave Observatory. The tidal forces acting on the neutron stars induce changes in the phase evolution of the gravitational waveform, and these changes can be used to constrain the nuclear equation of state. Current methods of generating BNS and BHNS waveforms rely on either computationally challenging full 3D hydrodynamical simulations or approximate analytic solutions. We introduce a new method for computing inspiral waveforms for BNS/BHNS systems by adding the post-Newtonian (PN) tidal effects to full numerical simulations of binary black holes (BBHs), effectively replacing the non-tidal terms in the PN expansion with BBH results. Comparing a waveform generated with this method against a full hydrodynamical simulation of a BNS inspiral yields a phase difference of < 1 radian over ~ 15 orbits. The numerical phase accuracy required of BNS simulations to measure the accuracy of the method we present here is estimated as a function of the tidal deformability parameter λ.

  11. Patterns of digital volume pulse waveform and pulse transit time in ...

    African Journals Online (AJOL)

    In this study the digital volume pulse wave and the pulse transit time of the thumb and big toe were analyzed in young and older subjects some of whom were hypertensive. We aimed to study the components and patterns of the pulse waveform and the pulse transit time and how they might change. Material and Methods: ...

  12. Full Waveform Inversion for Reservoir Characterization - A Synthetic Study

    KAUST Repository

    Zabihi Naeini, E.

    2017-05-26

    Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI) as an alternative tool for higher-resolution reservoir characterization. An important step in developing reservoir-oriented FWI is the implementation of facies-based rock physics constraints adapted from the classic methods. We show that such constraints can be incorporated into FWI by adding appropriately designed regularization terms to the objective function. The advantages of the proposed algorithm are demonstrated on both isotropic and VTI (transversely isotropic with a vertical symmetry axis) models with pronounced lateral and vertical heterogeneity. The inversion results are explained using the theoretical radiation patterns produced by perturbations in the medium parameters.

  13. Simulation of Transient Response of Ir-TES for Position-Sensitive TES with Waveform Domain Multiplexing

    Science.gov (United States)

    Minamikawa, Y.; Sato, H.; Mori, F.; Damayanthi, R. M. T.; Takahashi, H.; Ohno, M.

    2008-04-01

    We are developing a new x-ray microcalorimeter based on a superconducting transition edge sensor (TES) as an imaging sensor. Our measurement shows unique waveforms which we consider as an expression of thermal nonuniformity of TES films. This arises from the different thermal responses, so that response signal shapes would vary according to the position of the incident x-ray. This position dependency deteriorate the measured energy resolution, but with appropriate waveform analysis, this would be useful for imaging device. For more inspection, we have developed a simulation code which enables a dynamic simulation to obtain a transient response of the TES by finite differential method. Temperature and electric current distributions are calculated. As a result, we successfully obtained waveform signals. The calculated signal waveforms have similar characteristics to the measured signals. This simulation visualized the transition state of the device and will help to design better detector.

  14. Advances in waveform-agile sensing for tracking

    CERN Document Server

    Sira, Sandeep Prasad

    2009-01-01

    Recent advances in sensor technology and information processing afford a new flexibility in the design of waveforms for agile sensing. Sensors are now developed with the ability to dynamically choose their transmit or receive waveforms in order to optimize an objective cost function. This has exposed a new paradigm of significant performance improvements in active sensing: dynamic waveform adaptation to environment conditions, target structures, or information features. The manuscript provides a review of recent advances in waveform-agile sensing for target tracking applications. A dynamic wav

  15. Symbolic interactionism as a theoretical perspective for multiple method research.

    Science.gov (United States)

    Benzies, K M; Allen, M N

    2001-02-01

    Qualitative and quantitative research rely on different epistemological assumptions about the nature of knowledge. However, the majority of nurse researchers who use multiple method designs do not address the problem of differing theoretical perspectives. Traditionally, symbolic interactionism has been viewed as one perspective underpinning qualitative research, but it is also the basis for quantitative studies. Rooted in social psychology, symbolic interactionism has a rich intellectual heritage that spans more than a century. Underlying symbolic interactionism is the major assumption that individuals act on the basis of the meaning that things have for them. The purpose of this paper is to present symbolic interactionism as a theoretical perspective for multiple method designs with the aim of expanding the dialogue about new methodologies. Symbolic interactionism can serve as a theoretical perspective for conceptually clear and soundly implemented multiple method research that will expand the understanding of human health behaviour.

  16. Data Mining and Machine Learning Methods for Dementia Research.

    Science.gov (United States)

    Li, Rui

    2018-01-01

    Patient data in clinical research often includes large amounts of structured information, such as neuroimaging data, neuropsychological test results, and demographic variables. Given the various sources of information, we can develop computerized methods that can be a great help to clinicians to discover hidden patterns in the data. The computerized methods often employ data mining and machine learning algorithms, lending themselves as the computer-aided diagnosis (CAD) tool that assists clinicians in making diagnostic decisions. In this chapter, we review state-of-the-art methods used in dementia research, and briefly introduce some recently proposed algorithms subsequently.

  17. The research on business rules classification and specification methods

    OpenAIRE

    Baltrušaitis, Egidijus

    2005-01-01

    The work is based on the research of business rules classification and specification methods. The basics of business rules approach are discussed. The most common business rules classification and modeling methods are analyzed. Business rules modeling techniques and tools for supporting them in the information systems are presented. Basing on the analysis results business rules classification method is proposed. Templates for every business rule type are presented. Business rules structuring ...

  18. The challenge of conceptual stretching in multi-method research

    OpenAIRE

    Ahram, Ariel

    2009-01-01

    Multi-method research (MMR) has gained enthusiastic support among political scientists in recent years. Much of the impetus for MMR has been based on the seemingly intuitive logic of convergent triangulation: two tests are better than one, since a hypothesis that had survived a series of tests with different methods would be regarded as more valid than a hypothesis tested only a single method. In their seminal Design-ing Social Inquiry, King, Keohane, and Verba (1994) argue that combining qu...

  19. Perceptions of physiotherapists towards research: a mixed methods study.

    Science.gov (United States)

    Janssen, J; Hale, L; Mirfin-Veitch, B; Harland, T

    2016-06-01

    To explore the perceptions of physiotherapists towards the use of and participation in research. Concurrent mixed methods research, combining in-depth interviews with three questionnaires (demographics, Edmonton Research Orientation Survey, visual analogue scales for confidence and motivation to participate in research). One physiotherapy department in a rehabilitation hospital, consisting of seven specialised areas. Twenty-five subjects {four men and 21 women, mean age 38 [standard deviation (SD) 11] years} who had been registered as a physiotherapist for a mean period of 15 (SD 10) years participated in this study. They were registered with the New Zealand Board of Physiotherapy, held a current practising certificate, and were working as a physiotherapist or physiotherapy/allied health manager at the hospital. The primary outcome measure was in-depth interviews and the secondary outcome measures were the three questionnaires. Physiotherapists were generally positive towards research, but struggled with the concept of research, the available literature and the time to commit to research. Individual confidence and orientation towards research seemed to influence how these barriers were perceived. This study showed that physiotherapists struggle to implement research in their daily practice and become involved in research. Changing physiotherapists' conceptions of research, making it more accessible and providing dedicated research time could facilitate increased involvement in the physiotherapy profession. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  20. From research methods to methodical researcher: Making use of the student voice towards a more comprehensive module evaluation

    OpenAIRE

    Hast, Michael

    2015-01-01

    It is not uncommon for undergraduate students to feel aversion towards research methods teaching. This does not change the fact that research methods play a key role in their education. Targeting module design is imperative to ensure success. However, end-of-module student evaluations may provide a false sense of security regarding satisfaction and learnt knowledge. In order to approach module design more effectively it may instead be necessary to view module evaluations from a delayed perspe...

  1. Research Circles - a method for developing guidance practices

    DEFF Research Database (Denmark)

    2012-01-01

    This video reports on our work with using research circles to improve our understanding of how to provide guidance and counseling to help young people in danger of dropping out of school. The video is based on the paper: Research Circles -- a method for developing guidance practices, and was pres......This video reports on our work with using research circles to improve our understanding of how to provide guidance and counseling to help young people in danger of dropping out of school. The video is based on the paper: Research Circles -- a method for developing guidance practices......, and was presented at the Conference for Social Justice, Prosperity and Sustainable Employment 2012 by assistant professor Helle Merete Nordentoft from DPU (http://edu.au.dk/). The film communicating the research paper was created by Mie Nørgaard...

  2. Mixed-Methods Research in Nutrition and Dietetics.

    Science.gov (United States)

    Zoellner, Jamie; Harris, Jeffrey E

    2017-05-01

    This work focuses on mixed-methods research (MMR) and is the 11th in a series exploring the importance of research design, statistical analysis, and epidemiologic methods as applied to nutrition and dietetics research. MMR research is an investigative technique that applies both quantitative and qualitative data. The purpose of this article is to define MMR; describe its history and nature; provide reasons for its use; describe and explain the six different MMR designs; describe sample selection; and provide guidance in data collection, analysis, and inference. MMR concepts are applied and integrated with nutrition-related scenarios in real-world research contexts and summary recommendations are provided. Copyright © 2017 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  3. Methods in Entrepreneurship Education Research: A Review and Integrative Framework

    DEFF Research Database (Denmark)

    Blenker, Per; Trolle Elmholdt, Stine; Frederiksen, Signe Hedeboe

    2014-01-01

    is fragmented both conceptually and methodologically. Findings suggest that the methods applied in entrepreneurship education research cluster in two groups: 1. quantitative studies of the extent and effect of entrepreneurship education, and 2. qualitative single case studies of different courses and programmes....... It integrates qualitative and quantitative techniques, the use of research teams consisting of insiders (teachers studying their own teaching) and outsiders (research collaborators studying the education) as well as multiple types of data. To gain both in-depth and analytically generalizable studies...... a variety of helpful methods, explore the potential relation between insiders and outsiders in the research process, and discuss how different types of data can be combined. The integrated framework urges researchers to extend investments in methodological efforts and to enhance the in-depth understanding...

  4. Instrumental variable methods in comparative safety and effectiveness research.

    Science.gov (United States)

    Brookhart, M Alan; Rassen, Jeremy A; Schneeweiss, Sebastian

    2010-06-01

    Instrumental variable (IV) methods have been proposed as a potential approach to the common problem of uncontrolled confounding in comparative studies of medical interventions, but IV methods are unfamiliar to many researchers. The goal of this article is to provide a non-technical, practical introduction to IV methods for comparative safety and effectiveness research. We outline the principles and basic assumptions necessary for valid IV estimation, discuss how to interpret the results of an IV study, provide a review of instruments that have been used in comparative effectiveness research, and suggest some minimal reporting standards for an IV analysis. Finally, we offer our perspective of the role of IV estimation vis-à-vis more traditional approaches based on statistical modeling of the exposure or outcome. We anticipate that IV methods will be often underpowered for drug safety studies of very rare outcomes, but may be potentially useful in studies of intended effects where uncontrolled confounding may be substantial.

  5. A sheath model for arbitrary radiofrequency waveforms

    Science.gov (United States)

    Turner, M. M.; Chabert, Pascal

    2012-10-01

    The sheath is often the most important region of a rf plasma, because discharge impedance, power absorption and ion acceleration are critically affected by the behaviour of the sheath. Consequently, models of the sheath are central to any understanding of the physics of rf plasmas. Lieberman has supplied an analytical model for a radio-frequency sheath driven by a single frequency, but in recent years interest has been increasing in radio-frequency discharges excited by increasingly complex wave forms. There has been limited success in generalizing the Lieberman model in this direction, because of mathematical complexities. So there is essentially no sheath model available to describe many modern experiments. In this paper we present a new analytical sheath model, based on a simpler mathematical framework than that of Lieberman. For the single frequency case, this model yields scaling laws that are identical in form to those of Lieberman, differing only by numerical coefficients close to one. However, the new model may be straightforwardly solved for arbitrary current waveforms, and may be used to derive scaling laws for such complex waveforms. In this paper, we will describe the model and present some illustrative examples.

  6. Mixed methods in psychotherapy research: A review of method(ology) integration in psychotherapy science.

    Science.gov (United States)

    Bartholomew, Theodore T; Lockard, Allison J

    2018-06-13

    Mixed methods can foster depth and breadth in psychological research. However, its use remains in development in psychotherapy research. Our purpose was to review the use of mixed methods in psychotherapy research. Thirty-one studies were identified via the PRISMA systematic review method. Using Creswell & Plano Clark's typologies to identify design characteristics, we assessed each study for rigor and how each used mixed methods. Key features of mixed methods designs and these common patterns were identified: (a) integration of clients' perceptions via mixing; (b) understanding group psychotherapy; (c) integrating methods with cases and small samples; (d) analyzing clinical data as qualitative data; and (e) exploring cultural identities in psychotherapy through mixed methods. The review is discussed with respect to the value of integrating multiple data in single studies to enhance psychotherapy research. © 2018 Wiley Periodicals, Inc.

  7. Efficient blind search for similar-waveform earthquakes in years of continuous seismic data

    Science.gov (United States)

    Yoon, C. E.; Bergen, K.; Rong, K.; Elezabi, H.; Bailis, P.; Levis, P.; Beroza, G. C.

    2017-12-01

    Cross-correlating an earthquake waveform template with continuous seismic data has proven to be a sensitive, discriminating detector of small events missing from earthquake catalogs, but a key limitation of this approach is that it requires advance knowledge of the earthquake signals we wish to detect. To overcome this limitation, we can perform a blind search for events with similar waveforms, comparing waveforms from all possible times within the continuous data (Brown et al., 2008). However, the runtime for naive blind search scales quadratically with the duration of continuous data, making it impractical to process years of continuous data. The Fingerprint And Similarity Thresholding (FAST) detection method (Yoon et al., 2015) enables a comprehensive blind search for similar-waveform earthquakes in a fast, scalable manner by adapting data-mining techniques originally developed for audio and image search within massive databases. FAST converts seismic waveforms into compact "fingerprints", which are efficiently organized and searched within a database. In this way, FAST avoids the unnecessary comparison of dissimilar waveforms. To date, the longest duration of continuous data used for event detection with FAST was 3 months at a single station near Guy-Greenbrier, Arkansas, which revealed microearthquakes closely correlated with stages of hydraulic fracturing (Yoon et al., 2017). In this presentation we introduce an optimized, parallel version of the FAST software with improvements to the fingerprinting algorithm and the ability to detect events using continuous data from a network of stations (Bergen et al., 2016). We demonstrate its ability to detect low-magnitude earthquakes within several years of continuous data at locations of interest in California.

  8. DFT-Based Closed-form Covariance Matrix and Direct Waveforms Design for MIMO Radar to Achieve Desired Beampatterns

    KAUST Repository

    Bouchoucha, Taha

    2017-01-23

    In multiple-input multiple-out (MIMO) radar, for desired transmit beampatterns, appropriate correlated waveforms are designed. To design such waveforms, conventional MIMO radar methods use two steps. In the first step, the waveforms covariance matrix, R, is synthesized to achieve the desired beampattern. While in the second step, to realize the synthesized covariance matrix, actual waveforms are designed. Most of the existing methods use iterative algorithms to solve these constrained optimization problems. The computational complexity of these algorithms is very high, which makes them difficult to use in practice. In this paper, to achieve the desired beampattern, a low complexity discrete-Fourier-transform based closed-form covariance matrix design technique is introduced for a MIMO radar. The designed covariance matrix is then exploited to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope waveforms for the desired beampattern. The proposed technique can be used to design waveforms for large antenna array to change the beampattern in real time. It is also shown that the number of transmitted symbols from each antenna depends on the beampattern and is less than the total number of transmit antenna elements.

  9. Analysis of vibration waveforms of electromechanical response to determine piezoelectric and electrostrictive coefficients.

    Science.gov (United States)

    Izumi, Tatsuya; Hagiwara, Manabu; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2012-08-01

    We developed a possible method to determine both coefficients of piezoelectricity (d) and electrostriction (M) at the same time by a waveform analysis of current and vibration velocity in the resonance state. The waveforms of the current and vibration velocity were theoretically described using the equations of motion and piezoelectric constitutive equations, considering the dissipation effect. The dissipation factor of the d coefficient and M coefficient is dielectric loss tangent tan δ. The waveforms measured in all of the ceramics, such as Pb(Zr,Ti)O(3) (PZT), Pb(Mg,Nb)O(3) (PMN), and 0.8Pb(Mg(1/3)Nb2/3)O(3)-0.2PbTiO(3) (PMN-PT), were well fitted with the calculated waveform. This fitting produced both the d and M coefficients, which agreed with those determined via the conventional methods. Moreover, the respective contributions of both piezoelectricity and electrostriction to the d value determined in the resonance-antiresonance method were clarified.

  10. Social network analysis: Presenting an underused method for nursing research.

    Science.gov (United States)

    Parnell, James Michael; Robinson, Jennifer C

    2018-06-01

    This paper introduces social network analysis as a versatile method with many applications in nursing research. Social networks have been studied for years in many social science fields. The methods continue to advance but remain unknown to most nursing scholars. Discussion paper. English language and interpreted literature was searched from Ovid Healthstar, CINAHL, PubMed Central, Scopus and hard copy texts from 1965 - 2017. Social network analysis first emerged in nursing literature in 1995 and appears minimally through present day. To convey the versatility and applicability of social network analysis in nursing, hypothetical scenarios are presented. The scenarios are illustrative of three approaches to social network analysis and include key elements of social network research design. The methods of social network analysis are underused in nursing research, primarily because they are unknown to most scholars. However, there is methodological flexibility and epistemological versatility capable of supporting quantitative and qualitative research. The analytic techniques of social network analysis can add new insight into many areas of nursing inquiry, especially those influenced by cultural norms. Furthermore, visualization techniques associated with social network analysis can be used to generate new hypotheses. Social network analysis can potentially uncover findings not accessible through methods commonly used in nursing research. Social networks can be analysed based on individual-level attributes, whole networks and subgroups within networks. Computations derived from social network analysis may stand alone to answer a research question or incorporated as variables into robust statistical models. © 2018 John Wiley & Sons Ltd.

  11. Mixed Methods in Biomedical and Health Services Research

    Science.gov (United States)

    Curry, Leslie A.; Krumholz, Harlan M.; O’Cathain, Alicia; Plano Clark, Vicki L.; Cherlin, Emily; Bradley, Elizabeth H.

    2013-01-01

    Mixed methods studies, in which qualitative and quantitative methods are combined in a single program of inquiry, can be valuable in biomedical and health services research, where the complementary strengths of each approach can yield greater insight into complex phenomena than either approach alone. Although interest in mixed methods is growing among science funders and investigators, written guidance on how to conduct and assess rigorous mixed methods studies is not readily accessible to the general readership of peer-reviewed biomedical and health services journals. Furthermore, existing guidelines for publishing mixed methods studies are not well known or applied by researchers and journal editors. Accordingly, this paper is intended to serve as a concise, practical resource for readers interested in core principles and practices of mixed methods research. We briefly describe mixed methods approaches and present illustrations from published biomedical and health services literature, including in cardiovascular care, summarize standards for the design and reporting of these studies, and highlight four central considerations for investigators interested in using these methods. PMID:23322807

  12. Sampling Methods in Cardiovascular Nursing Research: An Overview.

    Science.gov (United States)

    Kandola, Damanpreet; Banner, Davina; O'Keefe-McCarthy, Sheila; Jassal, Debbie

    2014-01-01

    Cardiovascular nursing research covers a wide array of topics from health services to psychosocial patient experiences. The selection of specific participant samples is an important part of the research design and process. The sampling strategy employed is of utmost importance to ensure that a representative sample of participants is chosen. There are two main categories of sampling methods: probability and non-probability. Probability sampling is the random selection of elements from the population, where each element of the population has an equal and independent chance of being included in the sample. There are five main types of probability sampling including simple random sampling, systematic sampling, stratified sampling, cluster sampling, and multi-stage sampling. Non-probability sampling methods are those in which elements are chosen through non-random methods for inclusion into the research study and include convenience sampling, purposive sampling, and snowball sampling. Each approach offers distinct advantages and disadvantages and must be considered critically. In this research column, we provide an introduction to these key sampling techniques and draw on examples from the cardiovascular research. Understanding the differences in sampling techniques may aid nurses in effective appraisal of research literature and provide a reference pointfor nurses who engage in cardiovascular research.

  13. Trafficking and Health: A Systematic Review of Research Methods.

    Science.gov (United States)

    Cannon, Abby C; Arcara, Jennet; Graham, Laurie M; Macy, Rebecca J

    2018-04-01

    Trafficking in persons (TIP) is a human rights violation with serious public health consequences. Unfortunately, assessing TIP and its health sequelae rigorously and reliably is challenging due to TIP's clandestine nature, variation in definitions of TIP, and the need to use research methods that ensure studies are ethical and feasible. To help guide practice, policy, and research to assess TIP and health, we undertook a systematic literature review of 70 peer-reviewed, published articles to (a) identify TIP and health research methods being used, (b) determine what we can learn about TIP and health from these varied methodologies, and (c) determine the gaps that exist in health-focused TIP research. Results revealed that there are various quantitative and qualitative data collection and analysis methods being used to investigate TIP and health. Furthermore, findings show that the limitations of current methodologies affect what is known about TIP and health. In particular, varying definitions, participant recruitment strategies, ethical standards, and outcome measures all affect what is known about TIP and health. Moreover, findings demonstrate an urgent need for representative and nonpurposive recruitment strategies in future investigations of TIP and health as well as research on risk and protective factors related to TIP and health, intervention effectiveness, long-term health outcomes, and research on trafficked people beyond women trafficked for sex. We offer recommendations for research, policy, and practice based on review results.

  14. Kontexte qualitativer Sozialforschung: Arts-Based Research, Mixed Methods und Emergent Methods

    OpenAIRE

    Schreier, Margrit

    2017-01-01

    In dem vorliegenden Beitrag werden drei Kontexte qualitativer Sozialforschung genauer dargestellt, die in den vergangenen Jahren zunehmend an Bedeutung gewonnen haben: Arts-Based Research, Mixed Methods und Emergent Methods. Es werden verschiedene Ansätze und Varianten von Arts-Informed und Arts-Based Research genauer beschrieben, und es wird argumentiert, dass Arts-Based Research eine eigenständige Forschungstradition darstellt, die der qualitativen Sozialforschung wichtige Impulse geben kan...

  15. Mixed Methods Research: The "Thing-ness" Problem.

    Science.gov (United States)

    Hesse-Biber, Sharlene

    2015-06-01

    Contemporary mixed methods research (MMR) veers away from a "loosely bounded" to a "bounded" concept that has important negative implications for how qualitatively driven mixed methods approaches are positioned in the field of mixed methods and overall innovation in the praxis of MMR. I deploy the concept of reification defined as taking an object/abstraction and treating it as if it were real such that it takes on the quality of "thing-ness," having a concrete independent existence. I argue that the contemporary reification of mixed methods as a "thing" is fueled by three interrelated factors: (a) the growing formalization of mixed methods as design, (b) the unexamined belief in the "synergy" of mixed methods and, (c) the deployment of a "practical pragmatism" as the "philosophical partner" for mixed methods inquiry. © The Author(s) 2015.

  16. BREEAM [Building Research Establishment Environmental Assessment Method] BRE [Building Research Establishment] assessment method for buildings

    International Nuclear Information System (INIS)

    Baldwin, R.

    1994-01-01

    Buildings account for a large share of environmental impacts in their construction, use, and demolition. In western Europe, buildings account for ca 50% of primary energy use (hence CO 2 output), far outweighing the contribution of the transport and industrial sectors. Other impacts from building energy use include the use of chemicals such as chlorofluorocarbons for cooling. In the United Kingdom, the Building Research Establishment (BRE) has developed a certificate system for environmental labelling of buildings so that the performance of the building against a set of defined environmental criteria can be made visible to clients. This system thus rewards positive actions to improve the environmental performance of buildings and assists in marketing to an environmentally aware clientele. Issues included in assessments for awarding the certificate are addressed under three main headings: global issues and use of resources, local issues, and indoor issues. Global issues include ozone depletion and CO 2 emissions; local issues include public health and water conservation; and indoor issues include air quality and lighting. 8 refs., 1 tab

  17. Participatory action as a research method with public health nurses.

    Science.gov (United States)

    Cusack, Cheryl; Cohen, Benita; Mignone, Javier; Chartier, Mariette J; Lutfiyya, Zana

    2018-02-28

    This article explores and describes participatory action research (PAR) as a preferred method in addressing nursing practice issues. This is the first study that used PAR with public health nurses (PHNs) in Canada to develop a professional practice model. Participatory action research is a sub-category of action research that incorporates feminist and critical theory with foundations in the field of social psychology. For nurses, critical analysis of long-established beliefs and practices through PAR contributes to emancipatory knowledge regarding the impact of traditional hierarchies on their practice. This study used participatory action, a non-traditional but systematic research method, which assisted participants to develop a solution to a long-standing organizational issue. The stages of generating concerns, participatory action, acting on concerns, reflection and evaluation were implemented from 2012 - 2013 in an urban Canadian city, to develop a professional practice model for PHNs. Four sub-themes specific to PAR are discussed. These are "participatory action research engaged PHNs in development of a professional practice model;" "the participatory action research cycles of "Look, Think, Act" expanded participants' views;" "participatory action research increased awareness of organizational barriers;" and "participatory action research promoted individual empowerment and system transformation." This study resulted in individual and system change that may not have been possible without the use of PAR. The focus was engagement of participants and recognition of their lived experience, which facilitated PHNs' empowerment, leadership and consciousness-raising. © 2018 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

  18. Principles, Methods of Participatory Research: Proposal for Draft Animal Power

    Directory of Open Access Journals (Sweden)

    E. Chia

    2004-03-01

    Full Text Available The meeting of researchers, who question themselves on the efficiency of their actions when they accompany stakeholders during change processes, provides the opportunity to ponder on the research methods to develop when working together with the stakeholders: participative research, research-action, research-intervention… The author proposes to present the research-action approach as new. If the three phases of research-action are important, the negotiation phase is essential, because it enables contract formalization among partners (ethical aspect, development of a common language, and formalization of structuring efforts between researchers with various specialties and stakeholders. In the research-action approach, the managing set-ups (scientific committees… play a major role: they guarantee at the same time a solution to problems, production, and the legitimacy of the scientific knowledge produced. In conclusion, the author suggests ways to develop research-action in the field of animal traction in order to conceive new socio-technical and organizational innovations that will make the use of this technique easier.

  19. Introduction to quantitative research methods an investigative approach

    CERN Document Server

    Balnaves, Mark

    2001-01-01

    Introduction to Quantitative Research Methods is a student-friendly introduction to quantitative research methods and basic statistics. It uses a detective theme throughout the text and in multimedia courseware to show how quantitative methods have been used to solve real-life problems. The book focuses on principles and techniques that are appropriate to introductory level courses in media, psychology and sociology. Examples and illustrations are drawn from historical and contemporary research in the social sciences. The multimedia courseware provides tutorial work on sampling, basic statistics, and techniques for seeking information from databases and other sources. The statistics modules can be used as either part of a detective games or directly in teaching and learning. Brief video lessons in SPSS, using real datasets, are also a feature of the CD-ROM.

  20. An overview of methods for comparative effectiveness research.

    Science.gov (United States)

    Meyer, Anne-Marie; Wheeler, Stephanie B; Weinberger, Morris; Chen, Ronald C; Carpenter, William R

    2014-01-01

    Comparative effectiveness research (CER) is a broad category of outcomes research encompassing many different methods employed by researchers and clinicians from numerous disciplines. The goal of cancer-focused CER is to generate new knowledge to assist cancer stakeholders in making informed decisions that will improve health care and outcomes of both individuals and populations. There are numerous CER methods that may be used to examine specific questions, including randomized controlled trials, observational studies, systematic literature reviews, and decision sciences modeling. Each has its strengths and weaknesses. To both inform and serve as a reference for readers of this issue of Seminars in Radiation Oncology as well as the broader oncology community, we describe CER and several of the more commonly used approaches and analytical methods. © 2013 Published by Elsevier Inc.