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Sample records for adaptive waveform design

  1. Frequency Adaptability and Waveform Design for OFDM Radar Space-Time Adaptive Processing

    SciTech Connect

    Sen, Satyabrata; Glover, Charles Wayne

    2012-01-01

    We propose an adaptive waveform design technique for an orthogonal frequency division multiplexing (OFDM) radar signal employing a space-time adaptive processing (STAP) technique. We observe that there are inherent variabilities of the target and interference responses in the frequency domain. Therefore, the use of an OFDM signal can not only increase the frequency diversity of our system, but also improve the target detectability by adaptively modifying the OFDM coefficients in order to exploit the frequency-variabilities of the scenario. First, we formulate a realistic OFDM-STAP measurement model considering the sparse nature of the target and interference spectra in the spatio-temporal domain. Then, we show that the optimal STAP-filter weight-vector is equal to the generalized eigenvector corresponding to the minimum generalized eigenvalue of the interference and target covariance matrices. With numerical examples we demonstrate that the resultant OFDM-STAP filter-weights are adaptable to the frequency-variabilities of the target and interference responses, in addition to the spatio-temporal variabilities. Hence, by better utilizing the frequency variabilities, we propose an adaptive OFDM-waveform design technique, and consequently gain a significant amount of STAP-performance improvement.

  2. Waveform Design and Diversity for Advanced Space-Time Adaptive Processing and Multiple Input Multiple Output Systems

    DTIC Science & Technology

    2012-08-01

    13. SUPPLEMENTARY NOTES 14. ABSTRACT Waveform diversity refers to the adaptivity of the radar waveform to dynamically optimize the... radar performance for the particular scenario and tasks. It may also exploit adaptivity in other domains, including the antenna radiation pattern (both...Specifically, in Chapter 1, we consider the problem of waveform design for radar sensors that operate in a noncooperative network. In Chapter 2, we deal

  3. MURI: Adaptive Waveform Design for Full Spectral Dominance

    DTIC Science & Technology

    2011-03-11

    Glaser Steffen J; Luy Burkhard “Exploring the limits of broadband excitation and inversion: II. Rf-power optimized pulses,” Journal of magnetic resonance...Luy Burkhard ; Glaser Steffen J “ Linear phase slope in pulse design: application to coherence transfer,”Journal of magnetic resonance 2008; 192(2):235

  4. Adaptive OFDM waveform design for spatio-temporal-sparsity exploited STAP radar

    NASA Astrophysics Data System (ADS)

    Sen, Satyabrata; Barhen, Jacob

    2015-05-01

    We propose a sparsity-based space-time adaptive processing (STAP) algorithm to detect a slowly-moving target using an orthogonal frequency division multiplexing (OFDM) radar. The motivation of employing an OFDM signal is that it improves the target-detectability from the interfering signals by increasing the frequency diversity of the system. However, due to the addition of one extra dimension in terms of frequency, the adaptive degrees-of- freedom in an OFDM-STAP also increases. Therefore, to avoid the construction a fully-adaptive OFDM-STAP, we propose a sparsity-based STAP algorithm. We observe that the interference spectrum is inherently sparse in the spatio-temporal domain, as the clutter responses occupy only a diagonal ridge on the spatio-temporal plane and the jammer signals interfere only from a few spatial directions. Hence, we exploit that sparsity to develop an efficient STAP technique that utilizes considerably lesser number of secondary data compared to the other existing STAP techniques, and produces nearly optimum STAP performance. In addition to designing the STAP filter, we propose to optimally design the transmit OFDM signals by maximizing the output signal- to-interference-plus-noise ratio (SINR) in order to improve the STAP-performance. The computation of output SINR depends on the estimated value of the interference covariance matrix, which we obtain by applying the sparse recovery algorithm. Therefore, we analytically assess the effects of the synthesized OFDM coefficients on the sparse recovery of the interference covariance matrix by computing the coherence measure of the sparse measurement matrix. Our numerical examples demonstrate the achieved STAP-performance due to sparsity- based technique and adaptive waveform design.

  5. Performance bounds on micro-Doppler estimation and adaptive waveform design using OFDM signals

    NASA Astrophysics Data System (ADS)

    Sen, Satyabrata; Barhen, Jacob; Glover, Charles W.

    2014-05-01

    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Craḿer-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  6. Performance Bounds on Micro-Doppler Estimation and Adaptive Waveform Design Using OFDM Signals

    SciTech Connect

    Sen, Satyabrata; Barhen, Jacob; Glover, Charles Wayne

    2014-01-01

    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Cram er-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  7. Altimeter waveform software design

    NASA Technical Reports Server (NTRS)

    Hayne, G. S.; Miller, L. S.; Brown, G. S.

    1977-01-01

    Techniques are described for preprocessing raw return waveform data from the GEOS-3 radar altimeter. Topics discussed include: (1) general altimeter data preprocessing to be done at the GEOS-3 Data Processing Center to correct altimeter waveform data for temperature calibrations, to convert between engineering and final data units and to convert telemetered parameter quantities to more appropriate final data distribution values: (2) time "tagging" of altimeter return waveform data quantities to compensate for various delays, misalignments and calculational intervals; (3) data processing procedures for use in estimating spacecraft attitude from altimeter waveform sampling gates; and (4) feasibility of use of a ground-based reflector or transponder to obtain in-flight calibration information on GEOS-3 altimeter performance.

  8. Waveform Design for Wireless Power Transfer

    NASA Astrophysics Data System (ADS)

    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.

  9. ALES, the multi­mission Adaptive Leading Edge Sub­Waveform Retracker, design and validation

    NASA Astrophysics Data System (ADS)

    Passaro, Marcello; Benveniste, Jérôme; Vignudelli, Stefano; Cipollini, Paolo; Quartly, Graham; Snaith, Helen

    Satellite altimetry has revolutionized our understanding of ocean dynamics thanks to high repetition rate and global coverage. Nevertheless, coastal data has been flagged as unreliable due to land and calm water interference in the altimeter and radiometer footprint and high frequency tidal and atmospheric forcing. Our study addresses the first issue, i.e. retracking, presenting ALES, the Adaptive Leading Edge Subwaveform Retracker. ALES is potentially applicable to all the pulse­limited altimetry altimetry missions and its aim is to retrack with the same precision both open ocean and coastal data with the same algorithm. ALES selects part of each returned echo and models it with a classic ‘open ocean’ Brown functional form, by means of least square estimation whose convergence is found through the Nelder­Mead nonlinear optimization technique. By avoiding echoes from bright targets along the trailing edge, it is capable of retrieving the majority of coastal waveform up to 2 to 3 Km from the coasts. By adapting the estimation window to the significant wave height, it aims at preserving the precision of the standard data both in open ocean and in the coastal strip. ALES is validated against tide gauges in the Adriatic Sea and in the Greater Agulhas System for three different missions: Envisat, Jason­1 and Jason­2. Considerations on noise and biases provide a further verification of the strategy.

  10. Optimal radar waveform design for moving target

    NASA Astrophysics Data System (ADS)

    Zhu, Binqi; Gao, Yesheng; Wang, Kaizhi; Liu, Xingzhao

    2016-07-01

    An optimal radar waveform-design method is proposed to detect moving targets in the presence of clutter and noise. The clutter is split into moving and static parts. Radar-moving target/clutter models are introduced and combined with Neyman-Pearson criteria to design optimal waveforms. Results show that optimal waveform for a moving target is different with that for a static target. The combination of simple-frequency signals could produce maximum detectability based on different noise-power spectrum density situations. Simulations show that our algorithm greatly improves signal-to-clutter plus noise ratio of radar system. Therefore, this algorithm may be preferable for moving target detection when prior information on clutter and noise is available.

  11. Wideband Waveform Design principles for Solid-state Weather Radars

    SciTech Connect

    Bharadwaj, Nitin; Chandrasekar, V.

    2012-01-01

    The use of solid-state transmitter is becoming a key part of the strategy to realize a network of low cost electronically steered radars. However, solid-state transmitters have low peak powers and this necessitates the use of pulse compression waveforms. In this paper a frequency diversity wideband waveforms design is proposed to mitigate low sensitivity of solid-state transmitters. In addition, the waveforms mitigate the range eclipsing problem associated with long pulse compression. An analysis of the performance of pulse compression using mismatched compression filters designed to minimize side lobe levels is presented. The impact of range side lobe level on the retrieval of Doppler moments are presented. Realistic simulations are performed based on CSU-CHILL radar data and Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) radar data.

  12. Adaptive multi-step Full Waveform Inversion based on Waveform Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Hu, Yong; Han, Liguo; Xu, Zhuo; Zhang, Fengjiao; Zeng, Jingwen

    2017-04-01

    Full Waveform Inversion (FWI) can be used to build high resolution velocity models, but there are still many challenges in seismic field data processing. The most difficult problem is about how to recover long-wavelength components of subsurface velocity models when seismic data is lacking of low frequency information and without long-offsets. To solve this problem, we propose to use Waveform Mode Decomposition (WMD) method to reconstruct low frequency information for FWI to obtain a smooth model, so that the initial model dependence of FWI can be reduced. In this paper, we use adjoint-state method to calculate the gradient for Waveform Mode Decomposition Full Waveform Inversion (WMDFWI). Through the illustrative numerical examples, we proved that the low frequency which is reconstructed by WMD method is very reliable. WMDFWI in combination with the adaptive multi-step inversion strategy can obtain more faithful and accurate final inversion results. Numerical examples show that even if the initial velocity model is far from the true model and lacking of low frequency information, we still can obtain good inversion results with WMD method. From numerical examples of anti-noise test, we see that the adaptive multi-step inversion strategy for WMDFWI has strong ability to resist Gaussian noise. WMD method is promising to be able to implement for the land seismic FWI, because it can reconstruct the low frequency information, lower the dominant frequency in the adjoint source, and has a strong ability to resist noise.

  13. Design of a 9-loop quasi-exponential waveform generator.

    PubMed

    Banerjee, Partha; Shukla, Rohit; Shyam, Anurag

    2015-12-01

    We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.

  14. A Simple Adaptive Transfer Function for Deriving the Central Blood Pressure Waveform from a Radial Blood Pressure Waveform.

    PubMed

    Gao, Mingwu; Rose, William C; Fetics, Barry; Kass, David A; Chen, Chen-Huan; Mukkamala, Ramakrishna

    2016-09-14

    Generalized transfer functions (GTFs) are available to compute the more relevant central blood pressure (BP) waveform from a more easily measured radial BP waveform. However, GTFs are population averages and therefore may not adapt to variations in pulse pressure (PP) amplification (ratio of radial to central PP). A simple adaptive transfer function (ATF) was developed. First, the transfer function is defined in terms of the wave travel time and reflection coefficient parameters of an arterial model. Then, the parameters are estimated from the radial BP waveform by exploiting the observation that central BP waveforms exhibit exponential diastolic decays. The ATF was assessed using the original data that helped popularize the GTF. These data included radial BP waveforms and invasive reference central BP waveforms from cardiac catheterization patients. The data were divided into low, middle, and high PP amplification groups. The ATF estimated central BP with greater accuracy than GTFs in the low PP amplification group (e.g., central systolic BP and PP root-mean-square-errors of 3.3 and 4.2 mm Hg versus 6.2 and 7.1 mm Hg; p ≤ 0.05) while showing similar accuracy in the higher PP amplification groups. The ATF may permit more accurate, non-invasive central BP monitoring in elderly and hypertensive patients.

  15. A Simple Adaptive Transfer Function for Deriving the Central Blood Pressure Waveform from a Radial Blood Pressure Waveform

    PubMed Central

    Gao, Mingwu; Rose, William C.; Fetics, Barry; Kass, David A.; Chen, Chen-Huan; Mukkamala, Ramakrishna

    2016-01-01

    Generalized transfer functions (GTFs) are available to compute the more relevant central blood pressure (BP) waveform from a more easily measured radial BP waveform. However, GTFs are population averages and therefore may not adapt to variations in pulse pressure (PP) amplification (ratio of radial to central PP). A simple adaptive transfer function (ATF) was developed. First, the transfer function is defined in terms of the wave travel time and reflection coefficient parameters of an arterial model. Then, the parameters are estimated from the radial BP waveform by exploiting the observation that central BP waveforms exhibit exponential diastolic decays. The ATF was assessed using the original data that helped popularize the GTF. These data included radial BP waveforms and invasive reference central BP waveforms from cardiac catheterization patients. The data were divided into low, middle, and high PP amplification groups. The ATF estimated central BP with greater accuracy than GTFs in the low PP amplification group (e.g., central systolic BP and PP root-mean-square-errors of 3.3 and 4.2 mm Hg versus 6.2 and 7.1 mm Hg; p ≤ 0.05) while showing similar accuracy in the higher PP amplification groups. The ATF may permit more accurate, non-invasive central BP monitoring in elderly and hypertensive patients. PMID:27624389

  16. Design and Testing of Space Telemetry SCA Waveform

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.; Handler, Louis M.; Quinn, Todd M.

    2006-01-01

    A Software Communications Architecture (SCA) Waveform for space telemetry is being developed at the NASA Glenn Research Center (GRC). The space telemetry waveform is implemented in a laboratory testbed consisting of general purpose processors, field programmable gate arrays (FPGAs), analog-to-digital converters (ADCs), and digital-to-analog converters (DACs). The radio hardware is integrated with an SCA Core Framework and other software development tools. The waveform design is described from both the bottom-up signal processing and top-down software component perspectives. Simulations and model-based design techniques used for signal processing subsystems are presented. Testing with legacy hardware-based modems verifies proper design implementation and dynamic waveform operations. The waveform development is part of an effort by NASA to define an open architecture for space based reconfigurable transceivers. Use of the SCA as a reference has increased understanding of software defined radio architectures. However, since space requirements put a premium on size, mass, and power, the SCA may be impractical for today s space ready technology. Specific requirements for an SCA waveform and other lessons learned from this development are discussed.

  17. Waveform design for detection of weapons based on signature exploitation

    NASA Astrophysics Data System (ADS)

    Ahmad, Fauzia; Amin, Moeness G.; Dogaru, Traian

    2010-04-01

    We present waveform design based on signature exploitation techniques for improved detection of weapons in urban sensing applications. A single-antenna monostatic radar system is considered. Under the assumption of exact knowledge of the target orientation and, hence, known impulse response, matched illumination approach is used for optimal target detection. For the case of unknown target orientation, we analyze the target signatures as random processes and perform signal-to-noise-ratio based waveform optimization. Numerical electromagnetic modeling is used to provide the impulse responses of an AK-47 assault rifle for various target aspect angles relative to the radar. Simulation results depict an improvement in the signal-to-noise-ratio at the output of the matched filter receiver for both matched illumination and stochastic waveforms as compared to a chirp waveform of the same duration and energy.

  18. Integrated Range-Doppler Map and Extended Target Classification with Adaptive Waveform for Cognitive Radar

    DTIC Science & Technology

    2014-12-01

    wideband waveform. 14. SUBJECT TERMS waveform design, eigen waveform, ambiguity function, target identification , target detection , range Doppler map...are also interested in identification of extended targets . And finally, the third objective (which utilizes the results of the first two) is to...design an integrated scheme for the combined problem of range-Doppler location/ detection with extended target type identification with the use of a

  19. Efficient pulse compression for LPI waveforms based on a nonparametric iterative adaptive approach

    NASA Astrophysics Data System (ADS)

    Li, Zhengzheng; Nepal, Ramesh; Zhang, Yan; Blake, WIlliam

    2015-05-01

    In order to achieve low probability-of-intercept (LPI), radar waveforms are usually long and randomly generated. Due to the randomized nature, Matched filter responses (autocorrelation) of those waveforms can have high sidelobes which would mask weaker targets near a strong target, limiting radar's ability to distinguish close-by targets. To improve resolution and reduced sidelobe contaminations, a waveform independent pulse compression filter is desired. Furthermore, the pulse compression filter needs to be able to adapt to received signal to achieve optimized performance. As many existing pulse techniques require intensive computation, real-time implementation is infeasible. This paper introduces a new adaptive pulse compression technique for LPI waveforms that is based on a nonparametric iterative adaptive approach (IAA). Due to the nonparametric nature, no parameter tuning is required for different waveforms. IAA can achieve super-resolution and sidelobe suppression in both range and Doppler domains. Also it can be extended to directly handle the matched filter (MF) output (called MF-IAA), which further reduces the computational load. The practical impact of LPI waveform operations on IAA and MF-IAA has not been carefully studied in previous work. Herein the typical LPI waveforms such as random phase coding and other non- PI waveforms are tested with both single-pulse and multi-pulse IAA processing. A realistic airborne radar simulator as well as actual measured radar data are used for the validations. It is validated that in spite of noticeable difference with different test waveforms, the IAA algorithms and its improvement can effectively achieve range-Doppler super-resolution in realistic data.

  20. Waveform design for cognitive radar: target detection in heavy clutter

    NASA Astrophysics Data System (ADS)

    Kirk, Benjamin H.; Narayanan, Ram M.; Martone, Anthony F.; Sherbondy, Kelly D.

    2016-05-01

    In many applications of radar systems, detection of targets in environments with heavy clutter and interference can be difficult. It is desired that a radar system should detect targets at a further range as well as be able to detect these targets with very few false positive or negative readings. In a cognitive radar system, there are ways that these negative effects can be mitigated and target detection can be significantly improved. An important metric to focus on for increasing target detectability is the signal-to-clutter ratio (SCR). Cognitive radar offers solutions to issues such as this with the use of a priori knowledge of targets and environments as well as real time adaptations. A feature of cognitive radar that is of interest is the ability to adapt and optimize transmitted waveforms to a given situation. A database is used to hold a priori and dynamic knowledge of the operational environment and targets to be detected, such as clutter characteristics and target radar cross-section (RCS) estimations. Assuming this knowledge is available or can be estimated in real-time, the transmitted waveform can be tailored using methods such as transmission of a spectrum corresponding to the target-to-clutter ratio (TCR). These methods provide significant improvement in distinguishing targets from clutter or interference.

  1. Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

    DTIC Science & Technology

    2007-09-01

    correlation coefficient , or some comparable detection statistic, exceeds a given threshold. Since these methods exploit characteristic details of the full waveform, they provide exquisitely sensitive detectors with far lower detection thresholds than typical short-term average/long-term average (STA/LTA) algorithms. The drawback is that the form of the sought-after signal needs to be known quite accurately a priori, which limits such methods to instances of seismicity whereby a very similar signal has already been observed by every station used. Such instances include

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

    PubMed

    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.

  3. Optimal waveforms design for ultra-wideband impulse radio sensors.

    PubMed

    Li, Bin; Zhou, Zheng; Zou, Weixia; Li, Dejian; Zhao, Chong

    2010-01-01

    Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations.

  4. Optimal Waveforms Design for Ultra-Wideband Impulse Radio Sensors

    PubMed Central

    Li, Bin; Zhou, Zheng; Zou, Weixia; Li, Dejian; Zhao, Chong

    2010-01-01

    Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations. PMID:22163511

  5. PAPR-Constrained Pareto-Optimal Waveform Design for OFDM-STAP Radar

    SciTech Connect

    Sen, Satyabrata

    2014-01-01

    We propose a peak-to-average power ratio (PAPR) constrained Pareto-optimal waveform design approach for an orthogonal frequency division multiplexing (OFDM) radar signal to detect a target using the space-time adaptive processing (STAP) technique. The use of an OFDM signal does not only increase the frequency diversity of our system, but also enables us to adaptively design the OFDM coefficients in order to further improve the system performance. First, we develop a parametric OFDM-STAP measurement model by considering the effects of signaldependent clutter and colored noise. Then, we observe that the resulting STAP-performance can be improved by maximizing the output signal-to-interference-plus-noise ratio (SINR) with respect to the signal parameters. However, in practical scenarios, the computation of output SINR depends on the estimated values of the spatial and temporal frequencies and target scattering responses. Therefore, we formulate a PAPR-constrained multi-objective optimization (MOO) problem to design the OFDM spectral parameters by simultaneously optimizing four objective functions: maximizing the output SINR, minimizing two separate Cramer-Rao bounds (CRBs) on the normalized spatial and temporal frequencies, and minimizing the trace of CRB matrix on the target scattering coefficients estimations. We present several numerical examples to demonstrate the achieved performance improvement due to the adaptive waveform design.

  6. The use of fractally-designed waveforms in electroforming

    SciTech Connect

    Bullock, J.S.; Lawson, R.L.; Kirkpatrick, J.R.

    1996-03-01

    Pulsed electrodeposition offers the potential for superior control of deposit properties because of the additional control variables available. However, optimization of pulsed deposition processes is a challenge because of the complexity. E.g., the tendency of electroforms to acquire irregularities such as dendritic growths or other morphological instabilities, creates the need for methods to control these undesirable phenomena. One such method is periodic reverse pulses. Optimization of periodic reverse processes is not simple and can lead to local solutions that do not optimize all properties simultaneously. One method for global optimization that might, for example, control surface irregularities on several size scales, uses a periodic reverse design based on fractal time series. This incorporates deplating pulses of several lengths within one self- similar waveform. The properties of fractals permit control of highly complex designs with a small number of input variables. The creation of such waveforms, their properties, and their use in a lead- plating process are described. Speculation on the potential for further application of this method is offered. 26 figs, 11 refs.

  7. Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter.

    PubMed

    Yue, Wenzhen; Zhang, Yan; Liu, Yimin; Xie, Jingwen

    2016-06-17

    Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter's power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods.

  8. Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter

    PubMed Central

    Yue, Wenzhen; Zhang, Yan; Liu, Yimin; Xie, Jingwen

    2016-01-01

    Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter’s power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods. PMID:27322275

  9. Design and implementation of a hospital wide waveform capture system.

    PubMed

    Blum, James M; Joo, Heyon; Lee, Henry; Saeed, Mohammed

    2015-06-01

    The use of telemetry and invasive monitoring is exceptionally common in modern healthcare. To date the vast majority of this information is not stored for more than a brief duration on the local monitor. This prohibits extensive investigation into waveform data. We describe a system to collect such data in a quaternary care facility. Using standardized "packet sniffing" technology along with routine manual documentation, we reverse engineered the Unity network protocol used to transmit waveform data across the University of Michigan mission critical monitor network. Data was subsequently captured using a proprietary piece of software writing waveform data to local disks. Nightly, this data is post-processed using data from the admit-discharge-transfer system into individual patient waveforms for the day regardless of location. Over a 10 month period, over 2,785 individual patients had a total of 65,112 waveforms captured 15,978 from the operating rooms and 49,134 from the ICUs. The average OR case collected over 11 MB of data. The average single day data collection consisted of 8.6 GB of data. Entire hospital waveform data collection is possible using internally developed software enabling research on waveform data with minimal technical burden. Further research is required to determine the long-term storage and processing of such data.

  10. An adaptive subspace trust-region method for frequency-domain seismic full waveform inversion

    NASA Astrophysics Data System (ADS)

    Zhang, Huan; Li, Xiaofan; Song, Hanjie; Liu, Shaolin

    2015-05-01

    Full waveform inversion is currently considered as a promising seismic imaging method to obtain high-resolution and quantitative images of the subsurface. It is a nonlinear ill-posed inverse problem, the main difficulty of which that prevents the full waveform inversion from widespread applying to real data is the sensitivity to incorrect initial models and noisy data. Local optimization theories including Newton's method and gradient method always lead the convergence to local minima, while global optimization algorithms such as simulated annealing are computationally costly. To confront this issue, in this paper we investigate the possibility of applying the trust-region method to the full waveform inversion problem. Different from line search methods, trust-region methods force the new trial step within a certain neighborhood of the current iterate point. Theoretically, the trust-region methods are reliable and robust, and they have very strong convergence properties. The capability of this inversion technique is tested with the synthetic Marmousi velocity model and the SEG/EAGE Salt model. Numerical examples demonstrate that the adaptive subspace trust-region method can provide solutions closer to the global minima compared to the conventional Approximate Hessian approach and the L-BFGS method with a higher convergence rate. In addition, the match between the inverted model and the true model is still excellent even when the initial model deviates far from the true model. Inversion results with noisy data also exhibit the remarkable capability of the adaptive subspace trust-region method for low signal-to-noise data inversions. Promising numerical results suggest this adaptive subspace trust-region method is suitable for full waveform inversion, as it has stronger convergence and higher convergence rate.

  11. Waveform design for ultrasonic pulse-inversion fundamental imaging.

    PubMed

    Li, Pai-Chi; Shen, Che-Chou; Huang, Sheng-Wen

    2006-07-01

    Pulse-inversion (PI) fundamental imaging exhibits significantly better contrast detection than linear and second-harmonic imaging. PI fundamental imaging involves two firings with inverted waveforms. When the returning echoes from the two firings are summed, the residual signal related to tissue is limited to even-order harmonics, whereas for microbubbles, the fundamental signal is not completely canceled due to the echo under compression differing from that under rarefaction. The efficacy of PI fundamental imaging has been reported previously. In this study, we investigated the performance of PI fundamental imaging using both simulations and in vitro experiments with various transmit waveforms, including coded excitation and asymmetrical waveforms (i.e., asymmetrical between compression and rarefaction). For coded excitation, a longer waveform was found to increase the similarity in the responses to positive and negative pulses, thus lowering the contrast between microbubbles and tissue. In addition, imperfect pulse compression also decreases the contrast because it increases the residue fundamental signal emanating from tissue. Using asymmetrical waveforms noticeably increased the residual microbubble signal in the fundamental band but the nonzero DC component that is inherent in such waveforms also increases the tissue fundamental signal. The combination of these two effects decreases the contrast. From these results, it is concluded that the use of coded excitation is undesirable in PI fundamental imaging and that the waveforms should contain no DC component. Furthermore, the transmit waveform needs to be appropriately windowed in order to reduce spectral leakage. Therefore, a Gaussian pulse with the pulse length determined by the signal-to-noise ratio of the imaging system is generally optimal for PI fundamental imaging.

  12. Low probability of intercept-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems

    NASA Astrophysics Data System (ADS)

    Shi, Chenguang; Salous, Sana; Wang, Fei; Zhou, Jianjiang

    2016-12-01

    In this paper, we investigate the problem of low probability of intercept (LPI)-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems, where the radar system optimizes the transmitted waveform such that the interference caused to the cellular communication systems is strictly controlled. Assuming that the precise knowledge of the target spectra, the power spectral densities (PSDs) of signal-dependent clutters, the propagation losses of corresponding channels and the communication signals is known by the radar, three different LPI based criteria for radar waveform optimization are proposed to minimize the total transmitted power of the radar system by optimizing the multicarrier radar waveform with a predefined signal-to-interference-plus-noise ratio (SINR) constraint and a minimum required capacity for the cellular communication systems. These criteria differ in the way the communication signals scattered off the target are considered in the radar waveform design: (1) as useful energy, (2) as interference or (3) ignored altogether. The resulting problems are solved analytically and their solutions represent the optimum power allocation for each subcarrier in the multicarrier radar waveform. We show with numerical results that the LPI performance of the radar system can be significantly improved by exploiting the scattered echoes off the target due to cellular communication signals received at the radar receiver.

  13. Low probability of intercept-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems.

    PubMed

    Shi, Chenguang; Salous, Sana; Wang, Fei; Zhou, Jianjiang

    2016-01-01

    In this paper, we investigate the problem of low probability of intercept (LPI)-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems, where the radar system optimizes the transmitted waveform such that the interference caused to the cellular communication systems is strictly controlled. Assuming that the precise knowledge of the target spectra, the power spectral densities (PSDs) of signal-dependent clutters, the propagation losses of corresponding channels and the communication signals is known by the radar, three different LPI based criteria for radar waveform optimization are proposed to minimize the total transmitted power of the radar system by optimizing the multicarrier radar waveform with a predefined signal-to-interference-plus-noise ratio (SINR) constraint and a minimum required capacity for the cellular communication systems. These criteria differ in the way the communication signals scattered off the target are considered in the radar waveform design: (1) as useful energy, (2) as interference or (3) ignored altogether. The resulting problems are solved analytically and their solutions represent the optimum power allocation for each subcarrier in the multicarrier radar waveform. We show with numerical results that the LPI performance of the radar system can be significantly improved by exploiting the scattered echoes off the target due to cellular communication signals received at the radar receiver.

  14. Adaptive Sampling Designs.

    ERIC Educational Resources Information Center

    Flournoy, Nancy

    Designs for sequential sampling procedures that adapt to cumulative information are discussed. A familiar illustration is the play-the-winner rule in which there are two treatments; after a random start, the same treatment is continued as long as each successive subject registers a success. When a failure occurs, the other treatment is used until…

  15. Optimal Multicarrier Phase-Coded Waveform Design for Detection of Extended Targets

    SciTech Connect

    Sen, Satyabrata; Glover, Charles Wayne

    2013-01-01

    We design a parametric multicarrier phase-coded (MCPC) waveform that achieves the optimal performance in detecting an extended target in the presence of signal-dependent interference. Traditional waveform design techniques provide only the optimal energy spectral density of the transmit waveform and suffer a performance loss in the synthesis process of the time-domain signal. Therefore, we opt for directly designing an MCPC waveform in terms of its time-frequency codes to obtain the optimal detection performance. First, we describe the modeling assumptions considering an extended target buried within the signal-dependent clutter with known power spectral density, and deduce the performance characteristics of the optimal detector. Then, considering an MCPC signal transmission, we express the detection characteristics in terms of the phase-codes of the MCPC waveform and propose to optimally design the MCPC signal by maximizing the detection probability. Our numerical results demonstrate that the designed MCPC signal attains the optimal detection performance and requires a lesser computational time than the other parametric waveform design approach.

  16. Phase-modulated waveform design for extended target detection in the presence of clutter.

    PubMed

    Gong, Xuhua; Meng, Huadong; Wei, Yimin; Wang, Xiqin

    2011-01-01

    The problem to be addressed in this paper is a phase-modulated waveform design for the detection of extended targets contaminated by signal-dependent noise (clutter) and additive noise in practical radar systems. An optimal waveform design method that leads to the energy spectral density (ESD) of signal under the maximum signal-to-clutter-and-noise ratio (SCNR) criterion is introduced first. In order to make full use of the transmission power, a novel phase-iterative algorithm is then proposed for designing the phase-modulated waveform with a constant envelope, whose ESD matches the optimal one. This method is proven to be able to achieve a small SCNR loss by minimizing the mean-square spectral distance between the optimal waveform and the designed waveform. The results of extensive simulations demonstrate that our approach provides less than 1 dB SCNR loss when the signal duration is greater than 1 μs, and outperforms the stationary phase method and other phase-modulated waveform design methods.

  17. Robust constrained waveform design for MIMO radar with uncertain steering vectors

    NASA Astrophysics Data System (ADS)

    Yu, Xianxiang; Cui, Guolong; Piezzo, Marco; Iommelli, Salvatore; Kong, Lingjiang

    2017-01-01

    This paper considers the robust waveform design of multiple-input multiple-output (MIMO) radar to enhance targets detection in the presence of signal-dependent interferences assuming the knowledge of steering vectors is imprecise. Specifically, resorting to semidefinite programming (SDP)-related technique, we first maximize the worst-case signal-to-interference-plus-noise ratio (SINR) over uncertain region to optimize waveform covariance matrix forcing a uniform elemental power requirement. Then, based on least square (LS) approach, we devise the waveform accounting for constant modulus and similarity constraints by the obtained waveform covariance matrix using cyclic algorithm (CA). Finally, we assess the effectiveness of the proposed technique through numerical simulations in terms of non-uniform point-like clutter and uniform clutter.

  18. Model-Based Analysis and Design of Waveforms for Efficient Neural Stimulation

    PubMed Central

    Grill, Warren M.

    2016-01-01

    The design space for electrical stimulation of the nervous system is extremely large, and because the response to stimulation is highly non-linear, the selection of stimulation parameters to achieve a desired response is a challenging problem. Computational models of the response of neurons to extracellular stimulation allow analysis of the effects of stimulation parameters on neural excitation and provide an approach to select or design optimal parameters of stimulation. Here, I review the use of computational models to understand the effects of stimulation waveform on the energy efficiency of neural excitation and to design novel stimulation waveforms to increase the efficiency of neural stimulation. PMID:26541380

  19. Design of chirp excitation waveform for dual-frequency harmonic contrast detection.

    PubMed

    Shen, Che-Chou; Chiu, Yi-Yuan

    2009-10-01

    Tissue background suppression is essential for harmonic detection of ultrasonic contrast microbubbles. To reduce the tissue harmonic amplitude for improvement of contrast-to-tissue ratio (CTR), the method of third harmonic (3f(0)) transmit phasing uses an additional 3f(0) transmit signal to provide mutual cancellation between the frequency-sum component and the frequency-difference component of tissue harmonic signal. Chirp excitation can further improve the SNR in harmonic imaging without requiring an excessive transmit pressure and thus reduce potential bubble destruction. However, for effective suppression of tissue harmonic background in 3f(0) transmit phasing, the 3f(0) chirp waveform has to be carefully designed for the generation of spectrally matched cancellation pairs over the entire second harmonic band. In this study, we proposed a chirp waveform suitable for the method of 3f(0) transmit phasing, the different-bandwidth chirp signal (DBCS). With the DBCS waveform, the frequency-difference component of tissue harmonic signal becomes a chirp signal similar to its frequency-sum counterpart. Thus, the combination of the DBCS waveform with the 3f(0) transmit phasing can markedly suppress the tissue harmonic amplitude for CTR improvement together with effective SNR increase of contrast harmonic signal. Our results indicate that, as compared with the conventional Gaussian pulse, the DBCS waveform can provide 6-dB improvement of SNR in 3f(0) transmit phasing with a CTR increase of 3 dB. Nevertheless, the limitation of available transmit bandwidth and the frequency-dependent attenuation can degrade the performance of the DBCS waveform in tissue suppression. The design of the DBCS waveform is also applicable to other dual-frequency imaging techniques that rely on the harmonic generation at the difference frequency.

  20. Design of radio frequency pulse waveforms for mitigating signal inhomogeneity in magnetic resonance imaging due to metallic implants

    NASA Astrophysics Data System (ADS)

    Woo, Taeseong; Kim, Dongmin; Someya, Takao; Sekino, Masaki

    2015-05-01

    Metallic implants can result in considerable inhomogeneity in the signal intensity of magnetic resonance imaging (MRI), because the implant generates a shielding effect to the applied radio-frequency (RF) magnetic fields. In this study, we propose an acquisition method to mitigate the signal inhomogeneities using an adaptive RF pulse waveform. The effectiveness of the method was investigated using both numerical simulations and experiments. The RF pulse waveform was calculated based on inverse analyses of the Bloch equation incorporating the measured RF field distribution within the object. A simulation was carried out using a simplified numerical model of RF field inhomogeneity assumed at the center of model. An RF pulse waveform was designed to recover the attenuated signal region in the given model, and we show a significant improvement in the signal homogeneity compared with that obtained using a conventional pulse. We implemented the proposed method on a 7T-MRI system to show the efficacy experimentally. Test samples were fabricated from agarose gel with inserted copper or aluminum implants of different thicknesses. The RF pulse for selective excitation was calculated after mapping the RF field distribution of each imaging object. The acquired images exhibit an improvement in the homogeneity at the region of metallic implants. These results indicate that the proposed method is effective for MRI measurements of objects containing metallic implants.

  1. NORSAR Final Scientific Report Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

    SciTech Connect

    Gibbons, S J; Ringdal, F; Harris, D B

    2009-04-16

    Correlation detection is a relatively new approach in seismology that offers significant advantages in increased sensitivity and event screening over standard energy detection algorithms. The basic concept is that a representative event waveform is used as a template (i.e. matched filter) that is correlated against a continuous, possibly multichannel, data stream to detect new occurrences of that same signal. These algorithms are therefore effective at detecting repeating events, such as explosions and aftershocks at a specific location. This final report summarizes the results of a three-year cooperative project undertaken by NORSAR and Lawrence Livermore National Laboratory. The overall objective has been to develop and test a new advanced, automatic approach to seismic detection using waveform correlation. The principal goal is to develop an adaptive processing algorithm. By this we mean that the detector is initiated using a basic set of reference ('master') events to be used in the correlation process, and then an automatic algorithm is applied successively to provide improved performance by extending the set of master events selectively and strategically. These additional master events are generated by an independent, conventional detection system. A periodic analyst review will then be applied to verify the performance and, if necessary, adjust and consolidate the master event set. A primary focus of this project has been the application of waveform correlation techniques to seismic arrays. The basic procedure is to perform correlation on the individual channels, and then stack the correlation traces using zero-delay beam forming. Array methods such as frequency-wavenumber analysis can be applied to this set of correlation traces to help guarantee the validity of detections and lower the detection threshold. In principle, the deployment of correlation detectors against seismically active regions could involve very large numbers of very specific detectors. To

  2. Waveform Design and Scheduling in Space-Time Adaptive Radar

    DTIC Science & Technology

    2013-01-01

    scintillate in the PRI’s, the radar return from the p-th scatterer in the q-th clutter patch is given by pqs⌦ a(✓q,q)⌦ v( fcq ) where pq is its random...complex reflectivity, and fcq is the Doppler shift observed from the q-th clutter patch. It is implicitly assumed that the scatterers in a particular...identical to one another. The Doppler fcq is given by, fcq := 2foẋTr (xr xq) c||xr xq|| . (15) Since the clutter patch is stationary, the Doppler is

  3. Waveform Diversity and Design for Interoperating Radar Systems

    DTIC Science & Technology

    2013-01-01

    are completely passive, and hence undetectable. Among all the potential signals of opportunity we can mention FM radio and Digital Audio Broadcast...DAB) [DiL08], [Mal07], [How05], [Gre10], analogue TV and Digital Video Broadcast (DVB) [And05] [Gri86], [How99], Wi-Fi [Guo08] or cell phone network...signal emitted by another digital non co-operative transmitter of opportunity. Our research activity also concerned on the design of an algorithm

  4. Constant-Envelope Waveform Design for Optimal Target-Detection and Autocorrelation Performances

    SciTech Connect

    Sen, Satyabrata

    2013-01-01

    We propose an algorithm to directly synthesize in time-domain a constant-envelope transmit waveform that achieves the optimal performance in detecting an extended target in the presence of signal-dependent interference. This approach is in contrast to the traditional indirect methods that synthesize the transmit signal following the computation of the optimal energy spectral density. Additionally, we aim to maintain a good autocorrelation property of the designed signal. Therefore, our waveform design technique solves a bi-objective optimization problem in order to simultaneously improve the detection and autocorrelation performances, which are in general conflicting in nature. We demonstrate this compromising characteristics of the detection and autocorrelation performances with numerical examples. Furthermore, in the absence of the autocorrelation criterion, our designed signal is shown to achieve a near-optimum detection performance.

  5. Inherent secure communications using lattice based waveform design.

    SciTech Connect

    Pugh, Matthew Owen

    2013-12-01

    The wireless communications channel is innately insecure due to the broadcast nature of the electromagnetic medium. Many techniques have been developed and implemented in order to combat insecurities and ensure the privacy of transmitted messages. Traditional methods include encrypting the data via cryptographic methods, hiding the data in the noise floor as in wideband communications, or nulling the signal in the spatial direction of the adversary using array processing techniques. This work analyzes the design of signaling constellations, i.e. modulation formats, to combat eavesdroppers from correctly decoding transmitted messages. It has been shown that in certain channel models the ability of an adversary to decode the transmitted messages can be degraded by a clever signaling constellation based on lattice theory. This work attempts to optimize certain lattice parameters in order to maximize the security of the data transmission. These techniques are of interest because they are orthogonal to, and can be used in conjunction with, traditional security techniques to create a more secure communication channel.

  6. Waveform design for high-resolution damage detection using lamb waves.

    PubMed

    Zeng, Liang; Lin, Jing; Lei, Yaguo; Xie, Hang

    2013-05-01

    Dispersion is encountered very often in ultrasonic guided waves, and may decrease the performance for damage detection significantly. For this reason, many signal processing methods have been proposed to obtain each mode under serious dispersion. In this paper, a new scheme is established for waveform design to suppress the dispersion such that each wave packet can be separated clearly. In this method, the dispersion effect of the guided wave is pre-compensated for a particular distance as it propagates through the structure. The relationship between the resolvable resolution and the waveform parameters is discussed; this relationship is employed as a guide to separately identify the wave packets caused by different structural features. Subsequently, an experiment is carried out to compare the performance of the proposed method with the time-reversal method. By using the proposed method, closely distributed structural features can be recognized with ease in the time domain.

  7. Spatio-Temporal Waveform Design for Multiuser Massive MIMO Downlink With 1-bit Receivers

    NASA Astrophysics Data System (ADS)

    Gokceoglu, Ahmet; Bjornson, Emil; Larsson, Erik G.; Valkama, Mikko

    2017-03-01

    Internet-of-Things (IoT) refers to a high-density network of low-cost low-bitrate terminals and sensors where also low energy consumption is one central feature. As the power-budget of classical receiver chains is dominated by the high-resolution analog-to-digital converters (ADCs), there is a growing interest towards deploying receiver architectures with reduced-bit or even 1-bit ADCs. In this paper, we study waveform design, optimization and detection aspects of multi-user massive MIMO downlink where user terminals adopt very simple 1-bit ADCs with oversampling. In order to achieve spectral efficiency higher than 1 bit/s/Hz per real-dimension, we propose a two-stage precoding, namely a novel quantization precoder followed by maximum-ratio transmission (MRT) or zero-forcing (ZF) type spatial channel precoder which jointly form the multi-user-multiantenna transmit waveform. The quantization precoder outputs are optimized, under appropriate transmitter and receiver filter bandwidth constraints, to provide controlled inter-symbol-interference (ISI) enabling the input symbols to be uniquely detected from 1-bit quantized observations with a low-complexity symbol detector in the absence of noise. An additional optimization constraint is also imposed in the quantization precoder design to increase the robustness against noise and residual inter-user-interference (IUI). The purpose of the spatial channel precoder, in turn, is to suppress the IUI and provide high beamforming gains such that good symbol-error rates (SERs) can be achieved in the presence of noise and interference. Extensive numerical evaluations illustrate that the proposed spatio-temporal precoder based multiantenna waveform design can facilitate good multi-user link performance, despite the extremely simple 1-bit ADCs in the receivers, hence being one possible enabling technology for the future low-complexity IoT networks.

  8. The design and implementation of a multi-waveform radar echo simulator.

    PubMed

    Quan, Yinghui; Gao, Xiaoxiao; Li, Yachao; Xing, Mengdao

    2015-10-01

    Radar simulator is an effective tool for performance assessment of radar systems by accurately reproducing echo signals from complicated environment. This paper presents a design of fast multi-waveform radar echo generation based on deconvolution method. First, scene information is retrieved from outfield data based on improved conjugate gradient algorithm. Then, the new radar echoes are generated through convolution of new transmitted signal and restored scene information. A fast and area-efficient field programmable gate array realization is provided to meet the real-time requirement of radar echo simulation. Finally, a series of experiments are performed to evaluate the effectiveness of proposed radar simulation instrument.

  9. Equalizer design for clock recovery based on multi-level optical disk using signal waveform modulation

    NASA Astrophysics Data System (ADS)

    Shao, Meng; Pei, Jing; Yang, Bo

    2013-12-01

    With smaller pits and lands in multi-level optical disks using signal waveform modulation than those in DVD disks, the ISI and nonlinear attenuation of the read-out signal become more serious. One ordinary way is using an equalizer at sample rate 1/T, we proposed one method of designing the equalizer in fixed sample rate with digital interpolation. According to the analysis of the multi-level optical disk channel, we get the target frequency-response cure and implement it with seven order FIR filter. From the result of the read out experiment with multi-level optical disk, the clock of the RF signal could be recovered with the proposed equalizer.

  10. Adaptive clinical trial designs in oncology

    PubMed Central

    Zang, Yong; Lee, J. Jack

    2015-01-01

    Adaptive designs have become popular in clinical trial and drug development. Unlike traditional trial designs, adaptive designs use accumulating data to modify the ongoing trial without undermining the integrity and validity of the trial. As a result, adaptive designs provide a flexible and effective way to conduct clinical trials. The designs have potential advantages of improving the study power, reducing sample size and total cost, treating more patients with more effective treatments, identifying efficacious drugs for specific subgroups of patients based on their biomarker profiles, and shortening the time for drug development. In this article, we review adaptive designs commonly used in clinical trials and investigate several aspects of the designs, including the dose-finding scheme, interim analysis, adaptive randomization, biomarker-guided randomization, and seamless designs. For illustration, we provide examples of real trials conducted with adaptive designs. We also discuss practical issues from the perspective of using adaptive designs in oncology trials. PMID:25811018

  11. Dynamics of adaptive structures: Design through simulations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alexander, S.

    1993-01-01

    The use of a helical bi-morph actuator/sensor concept by mimicking the change of helical waveform in bacterial flagella is perhaps the first application of bacterial motions (living species) to longitudinal deployment of space structures. However, no dynamical considerations were analyzed to explain the waveform change mechanisms. The objective is to review various deployment concepts from the dynamics point of view and introduce the dynamical considerations from the outset as part of design considerations. Specifically, the impact of the incorporation of the combined static mechanisms and dynamic design considerations on the deployment performance during the reconfiguration stage is studied in terms of improved controllability, maneuvering duration, and joint singularity index. It is shown that intermediate configurations during articulations play an important role for improved joint mechanisms design and overall structural deployability.

  12. ERIS adaptive optics system design

    NASA Astrophysics Data System (ADS)

    Marchetti, Enrico; Le Louarn, Miska; Soenke, Christian; Fedrigo, Enrico; Madec, Pierre-Yves; Hubin, Norbert

    2012-07-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large Telescope (VLT) and the Adaptive Optics facility (AOF). It is an AO assisted instrument that will make use of the Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is planned for the Cassegrain focus of the telescope UT4. The project is currently in its Phase A awaiting for approval to continue to the next phases. The Adaptive Optics system of ERIS will include two wavefront sensors (WFS) to maximize the coverage of the proposed sciences cases. The first is a high order 40x40 Pyramid WFS (PWFS) for on axis Natural Guide Star (NGS) observations. The second is a high order 40x40 Shack-Hartmann WFS for single Laser Guide Stars (LGS) observations. The PWFS, with appropriate sub-aperture binning, will serve also as low order NGS WFS in support to the LGS mode with a field of view patrolling capability of 2 arcmin diameter. Both WFSs will be equipped with the very low read-out noise CCD220 based camera developed for the AOF. The real-time reconstruction and control is provided by a SPARTA real-time platform adapted to support both WFS modes. In this paper we will present the ERIS AO system in all its main aspects: opto-mechanical design, real-time computer design, control and calibrations strategy. Particular emphasis will be given to the system performance obtained via dedicated numerical simulations.

  13. A Design Method of Code Correlation Reference Waveform in GNSS Based on Least-Squares Fitting.

    PubMed

    Xu, Chengtao; Liu, Zhe; Tang, Xiaomei; Wang, Feixue

    2016-07-29

    The multipath effect is one of the main error sources in the Global Satellite Navigation Systems (GNSSs). The code correlation reference waveform (CCRW) technique is an effective multipath mitigation algorithm for the binary phase shift keying (BPSK) signal. However, it encounters the false lock problem in code tracking, when applied to the binary offset carrier (BOC) signals. A least-squares approximation method of the CCRW design scheme is proposed, utilizing the truncated singular value decomposition method. This algorithm was performed for the BPSK signal, BOC(1,1) signal, BOC(2,1) signal, BOC(6,1) and BOC(7,1) signal. The approximation results of CCRWs were presented. Furthermore, the performances of the approximation results are analyzed in terms of the multipath error envelope and the tracking jitter. The results show that the proposed method can realize coherent and non-coherent CCRW discriminators without false lock points. Generally, there is performance degradation in the tracking jitter, if compared to the CCRW discriminator. However, the performance promotions in the multipath error envelope for the BOC(1,1) and BPSK signals makes the discriminator attractive, and it can be applied to high-order BOC signals.

  14. A Design Method of Code Correlation Reference Waveform in GNSS Based on Least-Squares Fitting

    PubMed Central

    Xu, Chengtao; Liu, Zhe; Tang, Xiaomei; Wang, Feixue

    2016-01-01

    The multipath effect is one of the main error sources in the Global Satellite Navigation Systems (GNSSs). The code correlation reference waveform (CCRW) technique is an effective multipath mitigation algorithm for the binary phase shift keying (BPSK) signal. However, it encounters the false lock problem in code tracking, when applied to the binary offset carrier (BOC) signals. A least-squares approximation method of the CCRW design scheme is proposed, utilizing the truncated singular value decomposition method. This algorithm was performed for the BPSK signal, BOC(1,1) signal, BOC(2,1) signal, BOC(6,1) and BOC(7,1) signal. The approximation results of CCRWs were presented. Furthermore, the performances of the approximation results are analyzed in terms of the multipath error envelope and the tracking jitter. The results show that the proposed method can realize coherent and non-coherent CCRW discriminators without false lock points. Generally, there is performance degradation in the tracking jitter, if compared to the CCRW discriminator. However, the performance promotions in the multipath error envelope for the BOC(1,1) and BPSK signals makes the discriminator attractive, and it can be applied to high-order BOC signals. PMID:27483275

  15. Robust design of multiple-input multiple-output radar waveform covariance matrix in the presence of clutter

    NASA Astrophysics Data System (ADS)

    Guo, Rongyan; Wang, Hongyan

    2016-07-01

    In this work, the issue of robust waveform optimization is addressed in the presence of clutter to improve the worst-case estimation accuracy for collocated multiple-input multiple-output (MIMO) radar. Robust design is necessary due to the fact that waveform design may be sensitive to uncertainties in the initial parameter estimates. Following the min-max approach, the robust waveform covariance matrix design is formulated here on the basis of Cramér-Rao Bound to ease this sensitivity systematically for improving the worst-case accuracy. To tackle the resultant complicated and nonlinear problem, a new diagonal loading (DL)-based iterative approach is developed, in which the inner optimization problem can first be decomposed to some independent subproblems by using the Hadamard's inequality, and then these subproblems can be reformulated into convex issues by using DL method, as well as the outer optimization problem can also be relaxed to a convex issue by translating the nonlinear function into a linear one, and, hence, both of them can be solved very effectively. An optimal solution to the original problem can be obtained via the least-squares fitting of the solution acquired by the iterative approach. Numerical simulations show the efficiency of the proposed method.

  16. Designing for Productive Adaptations of Curriculum Interventions

    ERIC Educational Resources Information Center

    Debarger, Angela Haydel; Choppin, Jeffrey; Beauvineau, Yves; Moorthy, Savitha

    2013-01-01

    Productive adaptations at the classroom level are evidence-based curriculum adaptations that are responsive to the demands of a particular classroom context and still consistent with the core design principles and intentions of a curriculum intervention. The model of design-based implementation research (DBIR) offers insights into complexities and…

  17. Drought Adaptation Mechanisms Should Guide Experimental Design.

    PubMed

    Gilbert, Matthew E; Medina, Viviana

    2016-08-01

    The mechanism, or hypothesis, of how a plant might be adapted to drought should strongly influence experimental design. For instance, an experiment testing for water conservation should be distinct from a damage-tolerance evaluation. We define here four new, general mechanisms for plant adaptation to drought such that experiments can be more easily designed based upon the definitions. A series of experimental methods are suggested together with appropriate physiological measurements related to the drought adaptation mechanisms. The suggestion is made that the experimental manipulation should match the rate, length, and severity of soil water deficit (SWD) necessary to test the hypothesized type of drought adaptation mechanism.

  18. Model-based waveform design for optimal detection: A multi-objective approach to dealing with incomplete a priori knowledge.

    PubMed

    Hamschin, Brandon M; Loughlin, Patrick J

    2015-11-01

    This work considers the design of optimal, energy-constrained transmit signals for active sensing for the case when the designer has incomplete or uncertain knowledge of the target and/or environment. The mathematical formulation is that of a multi-objective optimization problem, wherein one can incorporate a plurality of potential targets, interference, or clutter models and in doing so take advantage of the wide range of results in the literature related to modeling each. It is shown, via simulation, that when the objective function of the optimization problem is chosen to maximize the minimum (i.e., maxmin) probability of detection among all possible model combinations, the optimal waveforms obtained are advantageous. The advantage results because the maxmin waveforms judiciously allocate energy to spectral regions where each of the target models respond strongly and each of the environmental models affect minimal detection performance degradation. In particular, improved detection performance is shown compared to linear frequency modulated transmit signals and compared to signals designed with the wrong target spectrum assumed. Additionally, it is shown that the maxmin design yields performance comparable to an optimal design matched to the correct target/environmental model. Finally, it is proven that the maxmin problem formulation is convex.

  19. Waveforms and Sonic Boom Perception and Response (WSPR): Low-Boom Community Response Program Pilot Test Design, Execution, and Analysis

    NASA Technical Reports Server (NTRS)

    Page, Juliet A.; Hodgdon, Kathleen K.; Krecker, Peg; Cowart, Robbie; Hobbs, Chris; Wilmer, Clif; Koening, Carrie; Holmes, Theresa; Gaugler, Trent; Shumway, Durland L.; Rosenberger, James L.; Philips, Daisy

    2014-01-01

    The Waveforms and Sonic boom Perception and Response (WSPR) Program was designed to test and demonstrate the applicability and effectiveness of techniques to gather data relating human subjective response to multiple low-amplitude sonic booms. It was in essence a practice session for future wider scale testing on naive communities, using a purpose built low-boom demonstrator aircraft. The low-boom community response pilot experiment was conducted in California in November 2011. The WSPR team acquired sufficient data to assess and evaluate the effectiveness of the various physical and psychological data gathering techniques and analysis methods.

  20. Dynamic optimization and adaptive controller design

    NASA Astrophysics Data System (ADS)

    Inamdar, S. R.

    2010-10-01

    In this work I present a new type of controller which is an adaptive tracking controller which employs dynamic optimization for optimizing current value of controller action for the temperature control of nonisothermal continuously stirred tank reactor (CSTR). We begin with a two-state model of nonisothermal CSTR which are mass and heat balance equations and then add cooling system dynamics to eliminate input multiplicity. The initial design value is obtained using local stability of steady states where approach temperature for cooling action is specified as a steady state and a design specification. Later we make a correction in the dynamics where material balance is manipulated to use feed concentration as a system parameter as an adaptive control measure in order to avoid actuator saturation for the main control loop. The analysis leading to design of dynamic optimization based parameter adaptive controller is presented. The important component of this mathematical framework is reference trajectory generation to form an adaptive control measure.

  1. SCA Waveform Development for Space Telemetry

    NASA Technical Reports Server (NTRS)

    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.

  2. Adaptive Automation Design and Implementation

    DTIC Science & Technology

    2015-09-17

    function instantiation. Finally, we develop five analysis tools for isolat ing effective AA points within a human -machine system. A function is an action... analysis tools allowing designers to identify points within a function network where the transitions between human and machine entities can facilitate...based on the four-stages of human information processing: sensory processing, perception /- working memory, decision making, and response selection

  3. Adaptive Strategies for Materials Design using Uncertainties.

    PubMed

    Balachandran, Prasanna V; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young's (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don't. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  4. Adaptive control design for hysteretic smart systems

    NASA Astrophysics Data System (ADS)

    Fan, Xiang; Smith, Ralph C.

    2009-03-01

    Ferroelectric and ferromagnetic actuators are being considered for a range of industrial, aerospace, aeronautic and biomedical applications due to their unique transduction capabilities. However, they also exhibit hysteretic and nonlinear behavior that must be accommodated in models and control designs. If uncompensated, these effects can yield reduced system performance and, in the worst case, can produce unpredictable behavior of the control system. One technique for control design is to approximately linearize the actuator dynamics using an adaptive inverse compensator that is also able to accommodate model uncertainties and error introduced by the inverse algorithm. This paper describes the design of an adaptive inverse control technique based on the homogenized energy model for hysteresis. The resulting inverse filter is incorporated in an L1 control theory to provide a robust control algorithm capable of providing high speed, high accuracy tracking in the presence of actuator hysteresis and nonlinearities. Properties of the control design are illustrated through numerical examples.

  5. Flexible receiver adapter formal design review

    SciTech Connect

    Krieg, S.A.

    1995-06-13

    This memo summarizes the results of the Formal (90%) Design Review process and meetings held to evaluate the design of the Flexible Receiver Adapters, support platforms, and associated equipment. The equipment is part of the Flexible Receiver System used to remove, transport, and store long length contaminated equipment and components from both the double and single-shell underground storage tanks at the 200 area tank farms.

  6. Numerical design of an adaptive aileron

    NASA Astrophysics Data System (ADS)

    Amendola, Gianluca; Dimino, Ignazio; Concilio, Antonio; Magnifico, Marco; Pecora, Rosario

    2016-04-01

    The study herein described is aimed at investigating the feasibility of an innovative full-scale camber morphing aileron device. In the framework of the "Adaptive Aileron" project, an international cooperation between Italy and Canada, this goal was carried out with the integration of different morphing concepts in a wing-tip prototype. As widely demonstrated in recent European projects such as Clean Sky JTI and SARISTU, wing trailing edge morphing may lead to significant drag reduction (up to 6%) in off-design flight points by adapting chord-wise camber variations in cruise to compensate A/C weight reduction following fuel consumption. Those researches focused on the flap region as the most immediate solution to implement structural adaptations. However, there is also a growing interest in extending morphing functionalities to the aileron region preserving its main functionality in controlling aircraft directional stability. In fact, the external region of the wing seems to be the most effective in producing "lift over drag" improvements by morphing. Thus, the objective of the presented research is to achieve a certain drag reduction in off-design flight points by adapting wing shape and lift distribution following static deflections. In perspective, the developed device could also be used as a load alleviation system to reduce gust effects, augmenting its frequency bandwidth. In this paper, the preliminary design of the adaptive aileron is first presented, assessed on the base of the external aerodynamic loads. The primary structure is made of 5 segmented ribs, distributed along 4 bays, each splitted into three consecutive parts, connected with spanwise stringers. The aileron shape modification is then implemented by means of an actuation system, based on a classical quick-return mechanism, opportunely suited for the presented application. Finite element analyses were assessed for properly sizing the load-bearing structure and actuation systems and for

  7. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph; Mortensen, Dale

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. The extension of STRS to the SSP hardware will promote easier waveform reconfiguration and reuse. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. A FPGA-based transmit waveform implementation of the proposed standard interfaces on a laboratory breadboard SDR will be discussed.

  8. Generating nonlinear FM chirp waveforms for radar.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Nonlinear FM waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.

  9. Application of Optimization Techniques to Spectrally Modulated, Spectrally Encoded Waveform Design

    DTIC Science & Technology

    2008-09-01

    communication applications include television ( TV ), AM radio, FM radio, and early cellular telephones. Digital communication techniques differ from analog...fourth generation ( 4G ) communication systems based on Cognitive Radio (CR) and Software Defined Radio (SDR) techniques. As 4G SMSE communications...design that replaces previous trial and error methods. The research objective has been achieved in the sense that 4G communication design engineers now

  10. Adaptive strategies for materials design using uncertainties

    SciTech Connect

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  11. Adaptive strategies for materials design using uncertainties

    DOE PAGES

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; ...

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material withmore » desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.« less

  12. Adaptive Strategies for Materials Design using Uncertainties

    PubMed Central

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-01

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties. PMID:26792532

  13. Adaptive Mesh Refinement for Microelectronic Device Design

    NASA Technical Reports Server (NTRS)

    Cwik, Tom; Lou, John; Norton, Charles

    1999-01-01

    Finite element and finite volume methods are used in a variety of design simulations when it is necessary to compute fields throughout regions that contain varying materials or geometry. Convergence of the simulation can be assessed by uniformly increasing the mesh density until an observable quantity stabilizes. Depending on the electrical size of the problem, uniform refinement of the mesh may be computationally infeasible due to memory limitations. Similarly, depending on the geometric complexity of the object being modeled, uniform refinement can be inefficient since regions that do not need refinement add to the computational expense. In either case, convergence to the correct (measured) solution is not guaranteed. Adaptive mesh refinement methods attempt to selectively refine the region of the mesh that is estimated to contain proportionally higher solution errors. The refinement may be obtained by decreasing the element size (h-refinement), by increasing the order of the element (p-refinement) or by a combination of the two (h-p refinement). A successful adaptive strategy refines the mesh to produce an accurate solution measured against the correct fields without undue computational expense. This is accomplished by the use of a) reliable a posteriori error estimates, b) hierarchal elements, and c) automatic adaptive mesh generation. Adaptive methods are also useful when problems with multi-scale field variations are encountered. These occur in active electronic devices that have thin doped layers and also when mixed physics is used in the calculation. The mesh needs to be fine at and near the thin layer to capture rapid field or charge variations, but can coarsen away from these layers where field variations smoothen and charge densities are uniform. This poster will present an adaptive mesh refinement package that runs on parallel computers and is applied to specific microelectronic device simulations. Passive sensors that operate in the infrared portion of

  14. A Tutorial on Adaptive Design Optimization

    PubMed Central

    Myung, Jay I.; Cavagnaro, Daniel R.; Pitt, Mark A.

    2013-01-01

    Experimentation is ubiquitous in the field of psychology and fundamental to the advancement of its science, and one of the biggest challenges for researchers is designing experiments that can conclusively discriminate the theoretical hypotheses or models under investigation. The recognition of this challenge has led to the development of sophisticated statistical methods that aid in the design of experiments and that are within the reach of everyday experimental scientists. This tutorial paper introduces the reader to an implementable experimentation methodology, dubbed Adaptive Design Optimization, that can help scientists to conduct “smart” experiments that are maximally informative and highly efficient, which in turn should accelerate scientific discovery in psychology and beyond. PMID:23997275

  15. Predicting electrocardiogram and arterial blood pressure waveforms with different Echo State Network architectures.

    PubMed

    Fong, Allan; Mittu, Ranjeev; Ratwani, Raj; Reggia, James

    2014-01-01

    Alarm fatigue caused by false alarms and alerts is an extremely important issue for the medical staff in Intensive Care Units. The ability to predict electrocardiogram and arterial blood pressure waveforms can potentially help the staff and hospital systems better classify a patient's waveforms and subsequent alarms. This paper explores the use of Echo State Networks, a specific type of neural network for mining, understanding, and predicting electrocardiogram and arterial blood pressure waveforms. Several network architectures are designed and evaluated. The results show the utility of these echo state networks, particularly ones with larger integrated reservoirs, for predicting electrocardiogram waveforms and the adaptability of such models across individuals. The work presented here offers a unique approach for understanding and predicting a patient's waveforms in order to potentially improve alarm generation. We conclude with a brief discussion of future extensions of this research.

  16. Dual adaptive control: Design principles and applications

    NASA Technical Reports Server (NTRS)

    Mookerjee, Purusottam

    1988-01-01

    The design of an actively adaptive dual controller based on an approximation of the stochastic dynamic programming equation for a multi-step horizon is presented. A dual controller that can enhance identification of the system while controlling it at the same time is derived for multi-dimensional problems. This dual controller uses sensitivity functions of the expected future cost with respect to the parameter uncertainties. A passively adaptive cautious controller and the actively adaptive dual controller are examined. In many instances, the cautious controller is seen to turn off while the latter avoids the turn-off of the control and the slow convergence of the parameter estimates, characteristic of the cautious controller. The algorithms have been applied to a multi-variable static model which represents a simplified linear version of the relationship between the vibration output and the higher harmonic control input for a helicopter. Monte Carlo comparisons based on parametric and nonparametric statistical analysis indicate the superiority of the dual controller over the baseline controller.

  17. Adaptive optical antennas: design and evaluation

    NASA Astrophysics Data System (ADS)

    Weyrauch, Thomas; Vorontsov, Mikhail A.; Carhart, Gary W.; Simonova, Galina V.; Beresnev, Leonid A.; Polnau, Ernst E.

    2007-09-01

    We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

  18. Valuation of design adaptability in aerospace systems

    NASA Astrophysics Data System (ADS)

    Fernandez Martin, Ismael

    As more information is brought into early stages of the design, more pressure is put on engineers to produce a reliable, high quality, and financially sustainable product. Unfortunately, requirements established at the beginning of a new project by customers, and the environment that surrounds them, continue to change in some unpredictable ways. The risk of designing a system that may become obsolete during early stages of production is currently tackled by the use of robust design simulation, a method that allows to simultaneously explore a plethora of design alternatives and requirements with the intention of accounting for uncertain factors in the future. Whereas this design technique has proven to be quite an improvement in design methods, under certain conditions, it fails to account for the change of uncertainty over time and the intrinsic value embedded in the system when certain design features are activated. This thesis introduces the concepts of adaptability and real options to manage risk foreseen in the face of uncertainty at early design stages. The method described herein allows decision-makers to foresee the financial impact of their decisions at the design level, as well as the final exposure to risk. In this thesis, cash flow models, traditionally used to obtain the forecast of a project's value over the years, were replaced with surrogate models that are capable of showing fluctuations on value every few days. This allowed a better implementation of real options valuation, optimization, and strategy selection. Through the option analysis model, an optimization exercise allows the user to obtain the best implementation strategy in the face of uncertainty as well as the overall value of the design feature. Here implementation strategy refers to the decision to include a new design feature in the system, after the design has been finalized, but before the end of its production life. The ability to do this in a cost efficient manner after the system

  19. Adaptive enrichment designs for clinical trials.

    PubMed

    Simon, Noah; Simon, Richard

    2013-09-01

    Modern medicine has graduated from broad spectrum treatments to targeted therapeutics. New drugs recognize the recently discovered heterogeneity of many diseases previously considered to be fairly homogeneous. These treatments attack specific genetic pathways which are only dysregulated in some smaller subset of patients with the disease. Often this subset is only rudimentarily understood until well into large-scale clinical trials. As such, standard practice has been to enroll a broad range of patients and run post hoc subset analysis to determine those who may particularly benefit. This unnecessarily exposes many patients to hazardous side effects, and may vastly decrease the efficiency of the trial (especially if only a small subset of patients benefit). In this manuscript, we propose a class of adaptive enrichment designs that allow the eligibility criteria of a trial to be adaptively updated during the trial, restricting entry to patients likely to benefit from the new treatment. We show that our designs both preserve the type 1 error, and in a variety of cases provide a substantial increase in power.

  20. Waveform design and Doppler sensitivity analysis for nonlinear FM chirp pulses

    NASA Astrophysics Data System (ADS)

    Johnston, J. A.; Fairhead, A. C.

    1986-04-01

    The use of pulse compression to obtain simultaneous long-range detection and good range resolution is described. The types of modulation that can be used to obtain pulse compression are outlined with particular emphasis on their performance under Doppler shift. It is shown that nonlinear frequency-modulated (FM) signals are capable of providing low range-sidelobes while being compressed using a matched filter. A design method for nonlinear FM signals based on window functions is outlined. Simulation results for pulse compression of nonlinear FM signals based on four different window functions with Doppler shift are presented. The results are used to define the effects of Doppler shift on the pulse compression. An analysis is presented, and interpreted pictorially, that explains the effects of Doppler shift on the pulse compression. The analysis is also extended to explain the better Doppler performance of hybrid FM pulse compression systems.

  1. HIV-1 vaccines and adaptive trial designs.

    PubMed

    Corey, Lawrence; Nabel, Gary J; Dieffenbach, Carl; Gilbert, Peter; Haynes, Barton F; Johnston, Margaret; Kublin, James; Lane, H Clifford; Pantaleo, Giuseppe; Picker, Louis J; Fauci, Anthony S

    2011-04-20

    Developing a vaccine against the human immunodeficiency virus (HIV) poses an exceptional challenge. There are no documented cases of immune-mediated clearance of HIV from an infected individual, and no known correlates of immune protection. Although nonhuman primate models of lentivirus infection have provided valuable data about HIV pathogenesis, such models do not predict HIV vaccine efficacy in humans. The combined lack of a predictive animal model and undefined biomarkers of immune protection against HIV necessitate that vaccines to this pathogen be tested directly in clinical trials. Adaptive clinical trial designs can accelerate vaccine development by rapidly screening out poor vaccines while extending the evaluation of efficacious ones, improving the characterization of promising vaccine candidates and the identification of correlates of immune protection.

  2. Dual-Frequency Alternating Current Designer Waveform for Reliable Voltammetric Determination of Electrode Kinetics Approaching the Reversible Limit.

    PubMed

    Li, Jiezhen; Bentley, Cameron L; Bond, Alan M; Zhang, Jie

    2016-02-16

    Alternating current (ac) voltammetry provides access to faster electrode kinetics than direct current (dc) methods. However, difficulties in ac and other methods arise when the heterogeneous electron-transfer rate constant (k(0)) approaches the reversible limit, because the voltammetric characteristics become insensitive to electrode kinetics. Thus, in this near-reversible regime, even small uncertainties associated with bulk concentration (C), diffusion coefficient (D), electrode area (A), and uncompensated resistance (Ru) can lead to significant systematic error in the determination of k(0). In this study, we have introduced a kinetically sensitive dual-frequency designer waveform into the Fourier-transformed large-amplitude alternating current (FTAC) voltammetric method that is made up of two sine waves having the same amplitude but with different frequencies (e.g., 37 and 615 Hz) superimposed onto a dc ramp to quantify the close-to-reversible Fc(0/+) process (Fc = ferrocene) in two nonhaloaluminate ionic liquids. The concept is that from a single experiment the lower-frequency data set, collected on a time scale where the target process is reversible, can be used as an internal reference to calibrate A, D, C, and Ru. These calibrated values are then used to calculate k(0) from analysis of the harmonics of the higher-frequency data set, where the target process is quasi-reversible. With this approach, k(0) values of 0.28 and 0.11 cm·s(-1) have been obtained at a 50 μm diameter platinum microdisk electrode for the close-to-diffusion-controlled Fc(0/+) process in two ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, respectively.

  3. Stable adaptive control using new critic designs

    NASA Astrophysics Data System (ADS)

    Werbos, Paul J.

    1999-03-01

    Classical adaptive control proves total-system stability for control of linear plants, but only for plants meeting very restrictive assumptions. Approximate Dynamic Programming (ADP) has the potential, in principle, to ensure stability without such tight restrictions. It also offers nonlinear and neural extensions for optimal control, with empirically supported links to what is seen in the brain. However, the relevant ADP methods in use today--TD, HDP, DHP, GDHP--and the Galerkin-based versions of these all have serious limitations when used here as parallel distributed real-time learning systems; either they do not possess quadratic unconditional stability (to be defined) or they lead to incorrect results in the stochastic case. (ADAC or Q- learning designs do not help.) After explaining these conclusions, this paper describes new ADP designs which overcome these limitations. It also addresses the Generalized Moving Target problem, a common family of static optimization problems, and describes a way to stabilize large-scale economic equilibrium models, such as the old long-term energy mode of DOE.

  4. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. Current standards were researched and new standard interfaces were proposed. The implementation of the proposed standard interfaces on a laboratory breadboard SDR will be presented.

  5. Some challenges with statistical inference in adaptive designs.

    PubMed

    Hung, H M James; Wang, Sue-Jane; Yang, Peiling

    2014-01-01

    Adaptive designs have generated a great deal of attention to clinical trial communities. The literature contains many statistical methods to deal with added statistical uncertainties concerning the adaptations. Increasingly encountered in regulatory applications are adaptive statistical information designs that allow modification of sample size or related statistical information and adaptive selection designs that allow selection of doses or patient populations during the course of a clinical trial. For adaptive statistical information designs, a few statistical testing methods are mathematically equivalent, as a number of articles have stipulated, but arguably there are large differences in their practical ramifications. We pinpoint some undesirable features of these methods in this work. For adaptive selection designs, the selection based on biomarker data for testing the correlated clinical endpoints may increase statistical uncertainty in terms of type I error probability, and most importantly the increased statistical uncertainty may be impossible to assess.

  6. Designing and Implementing Effective Adapted Physical Education Programs

    ERIC Educational Resources Information Center

    Kelly, Luke E.

    2011-01-01

    "Designing and Implementing Effective Adapted Physical Education Programs" was written to assist adapted and general physical educators who are dedicated to ensuring that the physical and motor needs of all their students are addressed in physical education. While it is anticipated that adapted physical educators, where available, will typically…

  7. Design for an Adaptive Library Catalog.

    ERIC Educational Resources Information Center

    Buckland, Michael K.; And Others

    1992-01-01

    Describes OASIS, a prototype adaptive online catalog implemented as a front end to the University of California MELVYL catalog. Topics addressed include the concept of adaptive retrieval systems, strategic search commands, feedback, prototyping using a front-end, the problem of excessive retrieval, commands to limit or increase search results, and…

  8. Designing and Generating Educational Adaptive Hypermedia Applications

    ERIC Educational Resources Information Center

    Retalis, Symeon; Papasalouros, Andreas

    2005-01-01

    Educational Adaptive Hypermedia Applications (EAHA) provide personalized views on the learning content to individual learners. They also offer adaptive sequencing (navigation) over the learning content based on rules that stem from the user model requirements and the instructional strategies. EAHA are gaining the focus of the research community as…

  9. [Design of modulating intermediate frequency electrotherapy system based on microcontroller unit].

    PubMed

    Yu, Xuefei; Liu, Xianfeng; Peng, Daming

    2010-12-01

    This article is devoted to the design of a system for modulating intermediate frequency electrotherapy waveform output. Prescriptions with different output waveform combinations were produced using microcontroller unit (MCU). The rich output waveforms effectively improve tolerance of human adaptability and achieve a therapeutic effect.

  10. Teacher-Led Design of an Adaptive Learning Environment

    ERIC Educational Resources Information Center

    Mavroudi, Anna; Hadzilacos, Thanasis; Kalles, Dimitris; Gregoriades, Andreas

    2016-01-01

    This paper discusses a requirements engineering process that exemplifies teacher-led design in the case of an envisioned system for adaptive learning. Such a design poses various challenges and still remains an open research issue in the field of adaptive learning. Starting from a scenario-based elicitation method, the whole process was highly…

  11. Robust design of configurations and parameters of adaptable products

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Chen, Yongliang; Xue, Deyi; Gu, Peihua

    2014-03-01

    An adaptable product can satisfy different customer requirements by changing its configuration and parameter values during the operation stage. Design of adaptable products aims at reducing the environment impact through replacement of multiple different products with single adaptable ones. Due to the complex architecture, multiple functional requirements, and changes of product configurations and parameter values in operation, impact of uncertainties to the functional performance measures needs to be considered in design of adaptable products. In this paper, a robust design approach is introduced to identify the optimal design configuration and parameters of an adaptable product whose functional performance measures are the least sensitive to uncertainties. An adaptable product in this paper is modeled by both configurations and parameters. At the configuration level, methods to model different product configuration candidates in design and different product configuration states in operation to satisfy design requirements are introduced. At the parameter level, four types of product/operating parameters and relations among these parameters are discussed. A two-level optimization approach is developed to identify the optimal design configuration and its parameter values of the adaptable product. A case study is implemented to illustrate the effectiveness of the newly developed robust adaptable design method.

  12. Adaptive Design of Confirmatory Trials: Advances and Challenges

    PubMed Central

    Lai, Tze Leung; Lavori, Philip W.; Tsang, Ka Wai

    2015-01-01

    The past decade witnessed major developments in innovative designs of confirmatory clinical trials, and adaptive designs represent the most active area of these developments. We give an overview of the developments and associated statistical methods in several classes of adaptive designs of confirmatory trials. We also discuss their statistical difficulties and implementation challenges, and show how these problems are connected to other branches of mainstream Statistics, which we then apply to resolve the difficulties and bypass the bottlenecks in the development of adaptive designs for the next decade. PMID:26079372

  13. Application of Adaptive Autopilot Designs for an Unmanned Aerial Vehicle

    NASA Technical Reports Server (NTRS)

    Shin, Yoonghyun; Calise, Anthony J.; Motter, Mark A.

    2005-01-01

    This paper summarizes the application of two adaptive approaches to autopilot design, and presents an evaluation and comparison of the two approaches in simulation for an unmanned aerial vehicle. One approach employs two-stage dynamic inversion and the other employs feedback dynamic inversions based on a command augmentation system. Both are augmented with neural network based adaptive elements. The approaches permit adaptation to both parametric uncertainty and unmodeled dynamics, and incorporate a method that permits adaptation during periods of control saturation. Simulation results for an FQM-117B radio controlled miniature aerial vehicle are presented to illustrate the performance of the neural network based adaptation.

  14. Simple Waveforms, Simply Described

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2008-01-01

    Since the first Lazarus Project calculations, it has been frequently noted that binary black hole merger waveforms are 'simple.' In this talk we examine some of the simple features of coalescence and merger waveforms from a variety of binary configurations. We suggest an interpretation of the waveforms in terms of an implicit rotating source. This allows a coherent description, of both the inspiral waveforms, derivable from post-Newtonian(PN) calculations, and the numerically determined merger-ringdown. We focus particularly on similarities in the features of various Multipolar waveform components Generated by various systems. The late-time phase evolution of most L these waveform components are accurately described with a sinple analytic fit. We also discuss apparent relationships among phase and amplitude evolution. Taken together with PN information, the features we describe can provide an approximate analytic description full coalescence wavefoRms. complementary to other analytic waveforns approaches.

  15. Adaptive design lessons from professional architects

    NASA Astrophysics Data System (ADS)

    Geiger, Ray W.; Snell, J. T.

    1993-09-01

    Psychocybernetic systems engineering design conceptualization is mimicking the evolutionary path of habitable environmental design and the professional practice of building architecture, construction, and facilities management. In pursuing better ways to design cellular automata and qualification classifiers in a design process, we have found surprising success in exploring certain more esoteric approaches, e.g., the vision of interdisciplinary artistic discovery in and around creative problem solving. Our evaluation in research into vision and hybrid sensory systems associated with environmental design and human factors has led us to discover very specific connections between the human spirit and quality design. We would like to share those very qualitative and quantitative parameters of engineering design, particularly as it relates to multi-faceted and future oriented design practice. Discussion covers areas of case- based techniques of cognitive ergonomics, natural modeling sources, and an open architectural process of means/goal satisfaction, qualified by natural repetition, gradation, rhythm, contrast, balance, and integrity of process.

  16. Adaptive and Adaptable Automation Design: A Critical Review of the Literature and Recommendations for Future Research

    NASA Technical Reports Server (NTRS)

    Prinzel, Lawrence J., III; Kaber, David B.

    2006-01-01

    This report presents a review of literature on approaches to adaptive and adaptable task/function allocation and adaptive interface technologies for effective human management of complex systems that are likely to be issues for the Next Generation Air Transportation System, and a focus of research under the Aviation Safety Program, Integrated Intelligent Flight Deck Project. Contemporary literature retrieved from an online database search is summarized and integrated. The major topics include the effects of delegation-type, adaptable automation on human performance, workload and situation awareness, the effectiveness of various automation invocation philosophies and strategies to function allocation in adaptive systems, and the role of user modeling in adaptive interface design and the performance implications of adaptive interface technology.

  17. Optimal adaptive sequential designs for crossover bioequivalence studies.

    PubMed

    Xu, Jialin; Audet, Charles; DiLiberti, Charles E; Hauck, Walter W; Montague, Timothy H; Parr, Alan F; Potvin, Diane; Schuirmann, Donald J

    2016-01-01

    In prior works, this group demonstrated the feasibility of valid adaptive sequential designs for crossover bioequivalence studies. In this paper, we extend the prior work to optimize adaptive sequential designs over a range of geometric mean test/reference ratios (GMRs) of 70-143% within each of two ranges of intra-subject coefficient of variation (10-30% and 30-55%). These designs also introduce a futility decision for stopping the study after the first stage if there is sufficiently low likelihood of meeting bioequivalence criteria if the second stage were completed, as well as an upper limit on total study size. The optimized designs exhibited substantially improved performance characteristics over our previous adaptive sequential designs. Even though the optimized designs avoided undue inflation of type I error and maintained power at ≥ 80%, their average sample sizes were similar to or less than those of conventional single stage designs.

  18. Design optimization of system level adaptive optical performance

    NASA Astrophysics Data System (ADS)

    Michels, Gregory J.; Genberg, Victor L.; Doyle, Keith B.; Bisson, Gary R.

    2005-09-01

    By linking predictive methods from multiple engineering disciplines, engineers are able to compute more meaningful predictions of a product's performance. By coupling mechanical and optical predictive techniques mechanical design can be performed to optimize optical performance. This paper demonstrates how mechanical design optimization using system level optical performance can be used in the development of the design of a high precision adaptive optical telescope. While mechanical design parameters are treated as the design variables, the objective function is taken to be the adaptively corrected optical imaging performance of an orbiting two-mirror telescope.

  19. Multidimensional Adaptive Testing with Optimal Design Criteria for Item Selection

    ERIC Educational Resources Information Center

    Mulder, Joris; van der Linden, Wim J.

    2009-01-01

    Several criteria from the optimal design literature are examined for use with item selection in multidimensional adaptive testing. In particular, it is examined what criteria are appropriate for adaptive testing in which all abilities are intentional, some should be considered as a nuisance, or the interest is in the testing of a composite of the…

  20. Categorisation of full waveform data provided by laser scanning devices

    NASA Astrophysics Data System (ADS)

    Ullrich, Andreas; Pfennigbauer, Martin

    2011-11-01

    In 2004, a laser scanner device for commercial airborne laser scanning applications, the RIEGL LMS-Q560, was introduced to the market, making use of a radical alternative approach to the traditional analogue signal detection and processing schemes found in LIDAR instruments so far: digitizing the echo signals received by the instrument for every laser pulse and analysing these echo signals off-line in a so-called full waveform analysis in order to retrieve almost all information contained in the echo signal using transparent algorithms adaptable to specific applications. In the field of laser scanning the somewhat unspecific term "full waveform data" has since been established. We attempt a categorisation of the different types of the full waveform data found in the market. We discuss the challenges in echo digitization and waveform analysis from an instrument designer's point of view and we will address the benefits to be gained by using this technique, especially with respect to the so-called multi-target capability of pulsed time-of-flight LIDAR instruments.

  1. Clothing adaptations: the occupational therapist and the clothing designer collaborate.

    PubMed

    White, L W; Dallas, M J

    1977-02-01

    An occupational therapist and a clothing designer collaborated in solving the dressing problem of a child with multiple amputations. The dressing problems were identified and solutions for clothing adaptations relating to sleeves, closures, fasteners, fit, and design were incorporated into two test garments. Evaluation of the garments was based on ease in dressing and undressing, the effect on movement and mobility, the construction techniques, and their appearance. A description is given of the pattern adjustments, and considerations for clothing adaptations or selection or both are discussed. These clothing adaptations can be generalized to a wider population of handicapped persons.

  2. Adapted RF Pulse Design for SAR Reduction in Parallel Excitation with Experimental Verification at 9.4 Tesla

    PubMed Central

    Wu, Xiaoping; Akgün, Can; Vaughan, J. Thomas; Andersen, Peter; Strupp, John; Uğurbil, Kâmil; Van de Moortele, Pierre-François

    2010-01-01

    Parallel excitation holds strong promises to mitigate the impact of large transmit B1 (B1+) distortion at very high magnetic field. Accelerated RF pulses, however, inherently tend to require larger values in RF peak power which may result in substantial increase in Specific Absorption Rate in tissues, which is a constant concern for patient safety at very high field. In this study, we demonstrate adapted rate RF pulse design allowing for SAR reduction while preserving excitation target accuracy. Compared with other proposed implementations of adapted rate RF pulses, our approach is compatible with any k-space trajectories, does not require an analytical expression of the gradient waveform and can be used for large flip angle excitation. We demonstrate our method with numerical simulations based on electromagnetic modeling and we include an experimental verification of transmit pattern accuracy on an 8 transmit channel 9.4 T system. PMID:20556882

  3. Seismic waveform viewer, processor and calculator

    SciTech Connect

    2015-02-15

    SWIFT is a computer code that is designed to do research level signal analysis on seismic waveforms, including visualization, filtering and measurement. LLNL is using this code, amplitude and global tomography efforts.

  4. Optimal Design of Item Banks for Computerized Adaptive Tests.

    ERIC Educational Resources Information Center

    Stocking, Martha L.; Swanson, Len

    1998-01-01

    Applied optimal design methods to the item-bank design of adaptive testing for continuous testing situations using a version of the weighted-deviations model (M. Stocking and L. Swanson, 1993) in a simulation. Independent and overlapping item banks used items more efficiently than did a large item bank. (SLD)

  5. Design of a digital adaptive control system for reentry vehicles.

    NASA Technical Reports Server (NTRS)

    Picon-Jimenez, J. L.; Montgomery, R. C.; Grigsby, L. L.

    1972-01-01

    The flying qualities of atmospheric reentry vehicles experience considerable variations due to the wide changes in flight conditions characteristic of reentry trajectories. A digital adaptive control system has been designed to modify the vehicle's dynamic characteristics and to provide desired flying qualities for all flight conditions. This adaptive control system consists of a finite-memory identifier which determines the vehicle's unknown parameters, and a gain computer which calculates feedback gains to satisfy flying quality requirements.

  6. On waveform multigrid method

    NASA Technical Reports Server (NTRS)

    Taasan, Shlomo; Zhang, Hong

    1993-01-01

    Waveform multigrid method is an efficient method for solving certain classes of time dependent PDEs. This paper studies the relationship between this method and the analogous multigrid method for steady-state problems. Using a Fourier-Laplace analysis, practical convergence rate estimates of the waveform multigrid iterations are obtained. Experimental results show that the analysis yields accurate performance prediction.

  7. Design of Low Complexity Model Reference Adaptive Controllers

    NASA Technical Reports Server (NTRS)

    Hanson, Curt; Schaefer, Jacob; Johnson, Marcus; Nguyen, Nhan

    2012-01-01

    Flight research experiments have demonstrated that adaptive flight controls can be an effective technology for improving aircraft safety in the event of failures or damage. However, the nonlinear, timevarying nature of adaptive algorithms continues to challenge traditional methods for the verification and validation testing of safety-critical flight control systems. Increasingly complex adaptive control theories and designs are emerging, but only make testing challenges more difficult. A potential first step toward the acceptance of adaptive flight controllers by aircraft manufacturers, operators, and certification authorities is a very simple design that operates as an augmentation to a non-adaptive baseline controller. Three such controllers were developed as part of a National Aeronautics and Space Administration flight research experiment to determine the appropriate level of complexity required to restore acceptable handling qualities to an aircraft that has suffered failures or damage. The controllers consist of the same basic design, but incorporate incrementally-increasing levels of complexity. Derivations of the controllers and their adaptive parameter update laws are presented along with details of the controllers implementations.

  8. Team-Centered Perspective for Adaptive Automation Design

    NASA Technical Reports Server (NTRS)

    Prinzel, Lawrence J., III

    2003-01-01

    Automation represents a very active area of human factors research. The journal, Human Factors, published a special issue on automation in 1985. Since then, hundreds of scientific studies have been published examining the nature of automation and its interaction with human performance. However, despite a dramatic increase in research investigating human factors issues in aviation automation, there remain areas that need further exploration. This NASA Technical Memorandum describes a new area of automation design and research, called adaptive automation. It discusses the concepts and outlines the human factors issues associated with the new method of adaptive function allocation. The primary focus is on human-centered design, and specifically on ensuring that adaptive automation is from a team-centered perspective. The document shows that adaptive automation has many human factors issues common to traditional automation design. Much like the introduction of other new technologies and paradigm shifts, adaptive automation presents an opportunity to remediate current problems but poses new ones for human-automation interaction in aerospace operations. The review here is intended to communicate the philosophical perspective and direction of adaptive automation research conducted under the Aerospace Operations Systems (AOS), Physiological and Psychological Stressors and Factors (PPSF) project.

  9. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater

  10. The Potential of Adaptive Design in Animal Studies.

    PubMed

    Majid, Arshad; Bae, Ok-Nam; Redgrave, Jessica; Teare, Dawn; Ali, Ali; Zemke, Daniel

    2015-10-12

    Clinical trials are the backbone of medical research, and are often the last step in the development of new therapies for use in patients. Prior to human testing, however, preclinical studies using animal subjects are usually performed in order to provide initial data on the safety and effectiveness of prospective treatments. These studies can be costly and time consuming, and may also raise concerns about the ethical treatment of animals when potentially harmful procedures are involved. Adaptive design is a process by which the methods used in a study may be altered while it is being conducted in response to preliminary data or other new information. Adaptive design has been shown to be useful in reducing the time and costs associated with clinical trials, and may provide similar benefits in preclinical animal studies. The purpose of this review is to summarize various aspects of adaptive design and evaluate its potential for use in preclinical research.

  11. The design of digital-adaptive controllers for VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Broussard, J. R.; Berry, P. W.

    1976-01-01

    Design procedures for VTOL automatic control systems have been developed and are presented. Using linear-optimal estimation and control techniques as a starting point, digital-adaptive control laws have been designed for the VALT Research Aircraft, a tandem-rotor helicopter which is equipped for fully automatic flight in terminal area operations. These control laws are designed to interface with velocity-command and attitude-command guidance logic, which could be used in short-haul VTOL operations. Developments reported here include new algorithms for designing non-zero-set-point digital regulators, design procedures for rate-limited systems, and algorithms for dynamic control trim setting.

  12. An overview of the adaptive designs accelerating promising trials into treatments (ADAPT-IT) project.

    PubMed

    Meurer, William J; Lewis, Roger J; Tagle, Danilo; Fetters, Michael D; Legocki, Laurie; Berry, Scott; Connor, Jason; Durkalski, Valerie; Elm, Jordan; Zhao, Wenle; Frederiksen, Shirley; Silbergleit, Robert; Palesch, Yuko; Berry, Donald A; Barsan, William G

    2012-10-01

    Randomized clinical trials, which aim to determine the efficacy and safety of drugs and medical devices, are a complex enterprise with myriad challenges, stakeholders, and traditions. Although the primary goal is scientific discovery, clinical trials must also fulfill regulatory, clinical, and ethical requirements. Innovations in clinical trials methodology have the potential to improve the quality of knowledge gained from trials, the protection of human subjects, and the efficiency of clinical research. Adaptive clinical trial methods represent a broad category of innovations intended to address a variety of long-standing challenges faced by investigators, such as sensitivity to previous assumptions and delayed identification of ineffective treatments. The implementation of adaptive clinical trial methods, however, requires greater planning and simulation compared with a more traditional design, along with more advanced administrative infrastructure for trial execution. The value of adaptive clinical trial methods in exploratory phase (phase 2) clinical research is generally well accepted, but the potential value and challenges of applying adaptive clinical trial methods in large confirmatory phase clinical trials are relatively unexplored, particularly in the academic setting. In the Adaptive Designs Accelerating Promising Trials Into Treatments (ADAPT-IT) project, a multidisciplinary team is studying how adaptive clinical trial methods could be implemented in planning actual confirmatory phase trials in an established, National Institutes of Health-funded clinical trials network. The overarching objectives of ADAPT-IT are to identify and quantitatively characterize the adaptive clinical trial methods of greatest potential value in confirmatory phase clinical trials and to elicit and understand the enthusiasms and concerns of key stakeholders that influence their willingness to try these innovative strategies.

  13. Bayesian response-adaptive designs for basket trials.

    PubMed

    Ventz, Steffen; Barry, William T; Parmigiani, Giovanni; Trippa, Lorenzo

    2017-02-17

    We develop a general class of response-adaptive Bayesian designs using hierarchical models, and provide open source software to implement them. Our work is motivated by recent master protocols in oncology, where several treatments are investigated simultaneously in one or multiple disease types, and treatment efficacy is expected to vary across biomarker-defined subpopulations. Adaptive trials such as I-SPY-2 (Barker et al., 2009) and BATTLE (Zhou et al., 2008) are special cases within our framework. We discuss the application of our adaptive scheme to two distinct research goals. The first is to identify a biomarker subpopulation for which a therapy shows evidence of treatment efficacy, and to exclude other subpopulations for which such evidence does not exist. This leads to a subpopulation-finding design. The second is to identify, within biomarker-defined subpopulations, a set of cancer types for which an experimental therapy is superior to the standard-of-care. This goal leads to a subpopulation-stratified design. Using simulations constructed to faithfully represent ongoing cancer sequencing projects, we quantify the potential gains of our proposed designs relative to conventional non-adaptive designs.

  14. Designing Adaptable Ships: Modularity and Flexibility in Future Ship Designs

    DTIC Science & Technology

    2016-01-01

    web page). v Contents Preface...55 Contents vii... integrated into the new design while reducing the construction cost of the ship. Recommendations We offer both short-term, ship-specific recommendations and

  15. Experimental Design to Evaluate Directed Adaptive Mutation in Mammalian Cells

    PubMed Central

    Chiaro, Christopher R; May, Tobias

    2014-01-01

    Background We describe the experimental design for a methodological approach to determine whether directed adaptive mutation occurs in mammalian cells. Identification of directed adaptive mutation would have profound practical significance for a wide variety of biomedical problems, including disease development and resistance to treatment. In adaptive mutation, the genetic or epigenetic change is not random; instead, the presence and type of selection influences the frequency and character of the mutation event. Adaptive mutation can contribute to the evolution of microbial pathogenesis, cancer, and drug resistance, and may become a focus of novel therapeutic interventions. Objective Our experimental approach was designed to distinguish between 3 types of mutation: (1) random mutations that are independent of selective pressure, (2) undirected adaptive mutations that arise when selective pressure induces a general increase in the mutation rate, and (3) directed adaptive mutations that arise when selective pressure induces targeted mutations that specifically influence the adaptive response. The purpose of this report is to introduce an experimental design and describe limited pilot experiment data (not to describe a complete set of experiments); hence, it is an early report. Methods An experimental design based on immortalization of mouse embryonic fibroblast cells is presented that links clonal cell growth to reversal of an inactivating polyadenylation site mutation. Thus, cells exhibit growth only in the presence of both the countermutation and an inducing agent (doxycycline). The type and frequency of mutation in the presence or absence of doxycycline will be evaluated. Additional experimental approaches would determine whether the cells exhibit a generalized increase in mutation rate and/or whether the cells show altered expression of error-prone DNA polymerases or of mismatch repair proteins. Results We performed the initial stages of characterizing our system

  16. Adaptive multibeam phased array design for a Spacelab experiment

    NASA Technical Reports Server (NTRS)

    Noji, T. T.; Fass, S.; Fuoco, A. M.; Wang, C. D.

    1977-01-01

    The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio.

  17. Adaptive Control Law Design for Model Uncertainty Compensation

    DTIC Science & Technology

    1989-06-14

    AD-A211 712 WRDC-TR-89-3061 ADAPTIVE CONTROL LAW DESIGN FOR MODEL UNCERTAINTY COMPENSATION J. E. SORRELLS DYNETICS , INC. U 1000 EXPLORER BLVD. L Ell...MONITORING ORGANIZATION Dynetics , Inc. (If applicable) Wright Research and Development Center netics,_ _ I _nc.Flight Dynamics Laboratory, AFSC 6c. ADDRESS...controllers designed using Dynetics innovative aporoach were able to equal or surpass the STR and MRAC controllers in terms of performance robustness

  18. Examining Teacher Thinking: Constructing a Process to Design Curricular Adaptations.

    ERIC Educational Resources Information Center

    Udvari-Solner, Alice

    1996-01-01

    This description of a curricular adaptation decision-making process focuses on tenets of reflective practice as teachers design instruction for students in heterogeneous classrooms. A case example illustrates how an elementary teaching team transformed lessons to accommodate a wide range of learners in a multiage first- and second-grade classroom.…

  19. Instructional Design and Adaptation Issues in Distance Learning Via Satellite.

    ERIC Educational Resources Information Center

    Thach, Liz

    1995-01-01

    Discusses a qualitative research study conducted in a distance-learning environment using satellite delivery. Describes changes in instructional design and adaptation issues which faculty and professionals involved in satellite-delivery learning situations used to be successful. (Author/AEF)

  20. Individually designed PALs vs. power optimized PALs adaptation comparison.

    PubMed

    Muždalo, Nataša Vujko; Mihelčič, Matjaž

    2015-03-01

    The practice shows that in everyday life we encounter ever-growing demand for better visual acuity at all viewing distances. The presbyopic population needs correction to far, near and intermediate distance with different dioptric powers. PAL lenses seem to be a comfortable solution. The object of the present study is the analysis of the factors determining adaptation to progressive addition lenses (PAL) of the first-time users. Only novice test persons were chosen in order to avoid the bias of previously worn particular lens design. For optimal results with this type of lens, several individual parameters must be considered: correct refraction, precise ocular and facial measures, and proper mounting of lenses into the frame. Nevertheless, first time wearers encounter various difficulties in the process of adapting to this type of glasses and adaptation time differs greatly between individual users. The question that arises is how much the individual parameters really affect the ease of adaptation and comfort when wearing progressive glasses. To clarify this, in the present study, the individual PAL lenses--Rodenstock's Impression FreeSign (with inclusion of all parameters related to the user's eye and spectacle frame: prescription, pupillary distance, fitting height, back vertex distance, pantoscopic angle and curvature of the frame) were compared to power optimized PAL--Rodenstock's Multigressiv MyView (respecting only prescription power and pupillary distance). Adaptation process was monitored over a period of four weeks. The collected results represent scores of user's subjective impressions, where the users themselves rated their adaptation to new progressive glasses and the degree of subjective visual impression. The results show that adaptation time to fully individually fit PAL is easier and quickly. The information obtained from users is valuable in everyday optometry practice because along with the manufacturer's specifications, the user's experience can

  1. Arterial waveform analysis.

    PubMed

    Esper, Stephen A; Pinsky, Michael R

    2014-12-01

    The bedside measurement of continuous arterial pressure values from waveform analysis has been routinely available via indwelling arterial catheterization for >50 years. Invasive blood pressure monitoring has been utilized in critically ill patients, in both the operating room and critical care units, to facilitate rapid diagnoses of cardiovascular insufficiency and monitor response to treatments aimed at correcting abnormalities before the consequences of either hypo- or hypertension are seen. Minimally invasive techniques to estimate cardiac output (CO) have gained increased appeal. This has led to the increased interest in arterial waveform analysis to provide this important information, as it is measured continuously in many operating rooms and intensive care units. Arterial waveform analysis also allows for the calculation of many so-called derived parameters intrinsically created by this pulse pressure profile. These include estimates of left ventricular stroke volume (SV), CO, vascular resistance, and during positive-pressure breathing, SV variation, and pulse pressure variation. This article focuses on the principles of arterial waveform analysis and their determinants, components of the arterial system, and arterial pulse contour. It will also address the advantage of measuring real-time CO by the arterial waveform and the benefits to measuring SV variation. Arterial waveform analysis has gained a large interest in the overall assessment and management of the critically ill and those at a risk of hemodynamic deterioration.

  2. Design of suboptimal adaptive filter for stochastic systems

    NASA Astrophysics Data System (ADS)

    Ahn, Jun Il; Shin, Vladimir

    2005-12-01

    In this paper, the problem of estimating the system state in for linear discrete-time systems with uncertainties is considered. In [1], [2], we have proposed the fusion formula (FF) for an arbitrary number of correlated and uncorrelated estimates. The FF is applied to detection and filtering problem. The new suboptimal adaptive filter with parallel structure is herein proposed. In consequence of parallel structure of the proposed filter, parallel computers can be used for their design. A lower computational complexity and lower memory demand are achieved with the proposed filter than in the optimal adaptive Lainiotis-Kalman filter. Example demonstrates the accuracy of the new filter.

  3. High-Voltage, Asymmetric-Waveform Generator

    NASA Technical Reports Server (NTRS)

    Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik

    2008-01-01

    The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise

  4. Adaptive Modeling, Engineering Analysis and Design of Advanced Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek; Hsu, Su-Yuen; Mason, Brian H.; Hicks, Mike D.; Jones, William T.; Sleight, David W.; Chun, Julio; Spangler, Jan L.; Kamhawi, Hilmi; Dahl, Jorgen L.

    2006-01-01

    This paper describes initial progress towards the development and enhancement of a set of software tools for rapid adaptive modeling, and conceptual design of advanced aerospace vehicle concepts. With demanding structural and aerodynamic performance requirements, these high fidelity geometry based modeling tools are essential for rapid and accurate engineering analysis at the early concept development stage. This adaptive modeling tool was used for generating vehicle parametric geometry, outer mold line and detailed internal structural layout of wing, fuselage, skin, spars, ribs, control surfaces, frames, bulkheads, floors, etc., that facilitated rapid finite element analysis, sizing study and weight optimization. The high quality outer mold line enabled rapid aerodynamic analysis in order to provide reliable design data at critical flight conditions. Example application for structural design of a conventional aircraft and a high altitude long endurance vehicle configuration are presented. This work was performed under the Conceptual Design Shop sub-project within the Efficient Aerodynamic Shape and Integration project, under the former Vehicle Systems Program. The project objective was to design and assess unconventional atmospheric vehicle concepts efficiently and confidently. The implementation may also dramatically facilitate physics-based systems analysis for the NASA Fundamental Aeronautics Mission. In addition to providing technology for design and development of unconventional aircraft, the techniques for generation of accurate geometry and internal sub-structure and the automated interface with the high fidelity analysis codes could also be applied towards the design of vehicles for the NASA Exploration and Space Science Mission projects.

  5. Design of Adaptive Policy Pathways under Deep Uncertainties

    NASA Astrophysics Data System (ADS)

    Babovic, Vladan

    2013-04-01

    The design of large-scale engineering and infrastructural systems today is growing in complexity. Designers need to consider sociotechnical uncertainties, intricacies, and processes in the long- term strategic deployment and operations of these systems. In this context, water and spatial management is increasingly challenged not only by climate-associated changes such as sea level rise and increased spatio-temporal variability of precipitation, but also by pressures due to population growth and particularly accelerating rate of urbanisation. Furthermore, high investment costs and long term-nature of water-related infrastructure projects requires long-term planning perspective, sometimes extending over many decades. Adaptation to such changes is not only determined by what is known or anticipated at present, but also by what will be experienced and learned as the future unfolds, as well as by policy responses to social and water events. As a result, a pathway emerges. Instead of responding to 'surprises' and making decisions on ad hoc basis, exploring adaptation pathways into the future provide indispensable support in water management decision-making. In this contribution, a structured approach for designing a dynamic adaptive policy based on the concepts of adaptive policy making and adaptation pathways is introduced. Such an approach provides flexibility which allows change over time in response to how the future unfolds, what is learned about the system, and changes in societal preferences. The introduced flexibility provides means for dealing with complexities of adaptation under deep uncertainties. It enables engineering systems to change in the face of uncertainty to reduce impacts from downside scenarios while capitalizing on upside opportunities. This contribution presents comprehensive framework for development and deployment of adaptive policy pathway framework, and demonstrates its performance under deep uncertainties on a case study related to urban

  6. The design of service-adaptive engine for robot middleware

    NASA Astrophysics Data System (ADS)

    Baek, BumHyeon; Choi, YongSoon; Park, Hong Seong

    2007-12-01

    In this paper, we propose a design of Service-Adaptive Engine for robot middleware. This middleware called the KOMoR (Korea Object-oriented Middleware of Robot) is a middleware for robot that composed of three layers (Service Layer, Network Adaptation Layer, Network Interface Layer). In particular, Service-Adaptive Engine in Service Layer is responsible for communication between distributed applications and provides a set of features that support development of realistic distributed applications for a robot. Also, it avoids unnecessary complexity, making the middleware easy to learn and to use. For writing application, both client and server consist of a mixture of application code, library code, and code generated from IDL definition called MIDL (Module Interface Definition Language). The Service-Adaptive Engine in SL contains the client-and server-side run-time support for remote communication. The generic part of the Service-Adaptive Engine (that is, the part that is independent of the specific types you have defined in MIDL) is accessed through the SL API. The proxy code is generated from MIDL definitions and, therefore specific to the types of objects and data you have defined in MIDL.

  7. Adaptive Designs for Randomized Trials in Public Health

    PubMed Central

    Brown, C. Hendricks; Have, Thomas R. Ten; Jo, Booil; Dagne, Getachew; Wyman, Peter A.; Muthén, Bengt; Gibbons, Robert D.

    2009-01-01

    In this article, we present a discussion of two general ways in which the traditional randomized trial can be modified or adapted in response to the data being collected. We use the term adaptive design to refer to a trial in which characteristics of the study itself, such as the proportion assigned to active intervention versus control, change during the trial in response to data being collected. The term adaptive sequence of trials refers to a decision-making process that fundamentally informs the conceptualization and conduct of each new trial with the results of previous trials. Our discussion below investigates the utility of these two types of adaptations for public health evaluations. Examples are provided to illustrate how adaptation can be used in practice. From these case studies, we discuss whether such evaluations can or should be analyzed as if they were formal randomized trials, and we discuss practical as well as ethical issues arising in the conduct of these new-generation trials. PMID:19296774

  8. Low frequency AC waveform generator

    DOEpatents

    Bilharz, Oscar W.

    1986-01-01

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stabilization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform itself. The cosine is synthesized by squaring the triangular waveform, raising the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  9. Spectrally-Temporally Adapted Spectrally Modulated Spectrally Encoded (SMSE) Waveform Design for Coexistent CR-Based SDR Applications

    DTIC Science & Technology

    2010-03-01

    Faculty Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command in Partial...the time and opportunity to continue my education , and the Laboratory for Telecommunica- tions Sciences for sponsoring this research. Eric C. Like vi...the ktℎ SMSE symbol according to sk[m] = NP−1∑ i=0 N ik−1∑ z=0 di, zk a i m,ku i,z m,kc i,z m,kwme jΘi,z m,k , (3.21) Θi,zm,k = ci,zm,k + di, zk + wm

  10. Full Waveform Inversion Using Waveform Sensitivity Kernels

    NASA Astrophysics Data System (ADS)

    Schumacher, Florian; Friederich, Wolfgang

    2013-04-01

    We present a full waveform inversion concept for applications ranging from seismological to enineering contexts, in which the steps of forward simulation, computation of sensitivity kernels, and the actual inversion are kept separate of each other. We derive waveform sensitivity kernels from Born scattering theory, which for unit material perturbations are identical to the Born integrand for the considered path between source and receiver. The evaluation of such a kernel requires the calculation of Green functions and their strains for single forces at the receiver position, as well as displacement fields and strains originating at the seismic source. We compute these quantities in the frequency domain using the 3D spectral element code SPECFEM3D (Tromp, Komatitsch and Liu, 2008) and the 1D semi-analytical code GEMINI (Friederich and Dalkolmo, 1995) in both, Cartesian and spherical framework. We developed and implemented the modularized software package ASKI (Analysis of Sensitivity and Kernel Inversion) to compute waveform sensitivity kernels from wavefields generated by any of the above methods (support for more methods is planned), where some examples will be shown. As the kernels can be computed independently from any data values, this approach allows to do a sensitivity and resolution analysis first without inverting any data. In the context of active seismic experiments, this property may be used to investigate optimal acquisition geometry and expectable resolution before actually collecting any data, assuming the background model is known sufficiently well. The actual inversion step then, can be repeated at relatively low costs with different (sub)sets of data, adding different smoothing conditions. Using the sensitivity kernels, we expect the waveform inversion to have better convergence properties compared with strategies that use gradients of a misfit function. Also the propagation of the forward wavefield and the backward propagation from the receiver

  11. An Adaptive Staggered Dose Design for a Normal Endpoint.

    PubMed

    Wu, Joseph; Menon, Sandeep; Chang, Mark

    2015-01-01

    In a clinical trial where several doses are compared to a control, a multi-stage design that combines both the selection of the best dose and the confirmation of this selected dose is desirable. An example is the two-stage drop-the-losers or pick-the-winner design, where inferior doses are dropped after interim analysis. Selection of target dose(s) can be based on ranking of observed effects, hypothesis testing with adjustment for multiplicity, or other criteria at interim stages. A number of methods have been proposed and have made significant gains in trial efficiency. However, many of these designs started off with all doses with equal allocation and did not consider prioritizing the doses using existing dose-response information. We propose an adaptive staggered dose procedure that allows explicit prioritization of doses and applies error spending scheme that favors doses with assumed better responses. This design starts off with only a subset of the doses and adaptively adds new doses depending on interim results. Using simulation, we have shown that this design performs better in terms of increased statistical power than the drop-the-losers design given strong prior information of dose response.

  12. A System Approach to Adaptive Multi-Modal Sensor Designs

    DTIC Science & Technology

    2010-02-01

    Email: rhody@cis.rit.edu Program Managers: Dr. Douglas Cochran <douglas.cochran@afosr.af.mil> Dr. Kitt C. Reinhardt <kitt.reinhardt...DEPARTMENT OF COMPUTER SCIENCE CONVENT AVE & 138TH ST SCHOOL OF ENGINEERING NEW YORK, NY 10031 Approved for public release...FA9550-08-1-0199 A System Approach to Adaptive Multi-Modal Sensor Designs 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

  13. Waveform information from quantum mechanical entropy

    NASA Astrophysics Data System (ADS)

    Funkhouser, Scott; Suski, William; Winn, Andrew

    2016-06-01

    Although the entropy of a given signal-type waveform is technically zero, it is nonetheless desirable to use entropic measures to quantify the associated information. Several such prescriptions have been advanced in the literature but none are generally successful. Here, we report that the Fourier-conjugated `total entropy' associated with quantum-mechanical probabilistic amplitude functions (PAFs) is a meaningful measure of information in non-probabilistic real waveforms, with either the waveform itself or its (normalized) analytic representation acting in the role of the PAF. Detailed numerical calculations are presented for both adaptations, showing the expected informatic behaviours in a variety of rudimentary scenarios. Particularly noteworthy are the sensitivity to the degree of randomness in a sequence of pulses and potential for detection of weak signals.

  14. Optimal Bayesian Adaptive Design for Test-Item Calibration.

    PubMed

    van der Linden, Wim J; Ren, Hao

    2015-06-01

    An optimal adaptive design for test-item calibration based on Bayesian optimality criteria is presented. The design adapts the choice of field-test items to the examinees taking an operational adaptive test using both the information in the posterior distributions of their ability parameters and the current posterior distributions of the field-test parameters. Different criteria of optimality based on the two types of posterior distributions are possible. The design can be implemented using an MCMC scheme with alternating stages of sampling from the posterior distributions of the test takers' ability parameters and the parameters of the field-test items while reusing samples from earlier posterior distributions of the other parameters. Results from a simulation study demonstrated the feasibility of the proposed MCMC implementation for operational item calibration. A comparison of performances for different optimality criteria showed faster calibration of substantial numbers of items for the criterion of D-optimality relative to A-optimality, a special case of c-optimality, and random assignment of items to the test takers.

  15. A Model for Designing Adaptive Laboratory Evolution Experiments.

    PubMed

    LaCroix, Ryan A; Palsson, Bernhard O; Feist, Adam M

    2017-04-15

    The occurrence of mutations is a cornerstone of the evolutionary theory of adaptation, capitalizing on the rare chance that a mutation confers a fitness benefit. Natural selection is increasingly being leveraged in laboratory settings for industrial and basic science applications. Despite increasing deployment, there are no standardized procedures available for designing and performing adaptive laboratory evolution (ALE) experiments. Thus, there is a need to optimize the experimental design, specifically for determining when to consider an experiment complete and for balancing outcomes with available resources (i.e., laboratory supplies, personnel, and time). To design and to better understand ALE experiments, a simulator, ALEsim, was developed, validated, and applied to the optimization of ALE experiments. The effects of various passage sizes were experimentally determined and subsequently evaluated with ALEsim, to explain differences in experimental outcomes. Furthermore, a beneficial mutation rate of 10(-6.9) to 10(-8.4) mutations per cell division was derived. A retrospective analysis of ALE experiments revealed that passage sizes typically employed in serial passage batch culture ALE experiments led to inefficient production and fixation of beneficial mutations. ALEsim and the results described here will aid in the design of ALE experiments to fit the exact needs of a project while taking into account the resources required and will lower the barriers to entry for this experimental technique.IMPORTANCE ALE is a widely used scientific technique to increase scientific understanding, as well as to create industrially relevant organisms. The manner in which ALE experiments are conducted is highly manual and uniform, with little optimization for efficiency. Such inefficiencies result in suboptimal experiments that can take multiple months to complete. With the availability of automation and computer simulations, we can now perform these experiments in an optimized

  16. Launch vehicle payload adapter design with vibration isolation features

    NASA Astrophysics Data System (ADS)

    Thomas, Gareth R.; Fadick, Cynthia M.; Fram, Bryan J.

    2005-05-01

    Payloads, such as satellites or spacecraft, which are mounted on launch vehicles, are subject to severe vibrations during flight. These vibrations are induced by multiple sources that occur between liftoff and the instant of final separation from the launch vehicle. A direct result of the severe vibrations is that fatigue damage and failure can be incurred by sensitive payload components. For this reason a payload adapter has been designed with special emphasis on its vibration isolation characteristics. The design consists of an annular plate that has top and bottom face sheets separated by radial ribs and close-out rings. These components are manufactured from graphite epoxy composites to ensure a high stiffness to weight ratio. The design is tuned to keep the frequency of the axial mode of vibration of the payload on the flexibility of the adapter to a low value. This is the main strategy adopted for isolating the payload from damaging vibrations in the intermediate to higher frequency range (45Hz-200Hz). A design challenge for this type of adapter is to keep the pitch frequency of the payload above a critical value in order to avoid dynamic interactions with the launch vehicle control system. This high frequency requirement conflicts with the low axial mode frequency requirement and this problem is overcome by innovative tuning of the directional stiffnesses of the composite parts. A second design strategy that is utilized to achieve good isolation characteristics is the use of constrained layer damping. This feature is particularly effective at keeping the responses to a minimum for one of the most important dynamic loading mechanisms. This mechanism consists of the almost-tonal vibratory load associated with the resonant burn condition present in any stage powered by a solid rocket motor. The frequency of such a load typically falls in the 45-75Hz range and this phenomenon drives the low frequency design of the adapter. Detailed finite element analysis is

  17. Design of an adaptive controller for a telerobot manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Zhou, Zhen-Lei

    1989-01-01

    The design of a joint-space adaptive control scheme is presented for controlling the slave arm motion of a dual-arm telerobot system developed at Goddard Space Flight Center (GSFC) to study telerobotic operations in space. Each slave arm of the dual-arm system is a kinematically redundant manipulator with 7 degrees of freedom (DOF). Using the concept of model reference adaptive control (MRAC) and Lyapunov direct method, an adatation algorithm is derived which adjusts the PD controller gains of the control scheme. The development of the adaptive control scheme assumes that the slave arm motion is non-compliant and slowly-varying. The implementation of the derived control scheme does not need the computation of the manipulator dynamics, which makes the control scheme sufficiently fast for real-time applications. Computer simulation study performed for the 7-DOF slave arm shows that the developed control scheme can efficiently adapt to sudden change in payloads while tracking various test trajectories such as ramp or sinusoids with negligible position errors.

  18. Hybrid Computerized Adaptive Testing: From Group Sequential Design to Fully Sequential Design

    ERIC Educational Resources Information Center

    Wang, Shiyu; Lin, Haiyan; Chang, Hua-Hua; Douglas, Jeff

    2016-01-01

    Computerized adaptive testing (CAT) and multistage testing (MST) have become two of the most popular modes in large-scale computer-based sequential testing. Though most designs of CAT and MST exhibit strength and weakness in recent large-scale implementations, there is no simple answer to the question of which design is better because different…

  19. Adaptive Optics System Design and Operation at Lick Observatory

    NASA Astrophysics Data System (ADS)

    Olivier, S. S.; Max, C. E.; Avicola, K.; Bissinger, H. D.; Brase, J. M.; Friedman, H. W.; Gavel, D. T.; Salmon, J. T.; Waltjen, K. E.

    1993-12-01

    An adaptive optics system developed for the 40 inch Nickel and 120 inch Shane telescopes at Lick Observatory is described. The adaptive optics system design is based on a 69 actuator continuous-surface deformable mirror and a Hartmann wavefront sensor equipped with a commercial intensified CCD fast-framing camera. The system has been tested at the Cassegrain focus of the 40 inch Nickel telescope where the subaperture diameter is 12 cm. The subaperture slope and mirror control calculations are performed on a four processor single board computer controlled by a Unix workstation. This configuration is capable of up to 1 KHz frame rates. The optical configuration of the system and its interface to the telescope is described. Details of the control system design, operation, and user interface are given. Initial test results emphasizing control system operations of this adaptive optics system using natural reference stars on the 40 inch Nickel telescope are presented. The initial test results are compared to predictions from analyses and simulations. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  20. The VIADUC project: innovation in climate adaptation through service design

    NASA Astrophysics Data System (ADS)

    Corre, L.; Dandin, P.; L'Hôte, D.; Besson, F.

    2015-07-01

    From the French National Adaptation to Climate Change Plan, the "Drias, les futurs du climat" service has been developed to provide easy access to French regional climate projections. This is a major step for the implementation of French Climate Services. The usefulness of this service for the end-users and decision makers involved with adaptation planning at a local scale is investigated. As such, the VIADUC project is: to evaluate and enhance Drias, as well as to imagine future development in support of adaptation. Climate scientists work together with end-users and a service designer. The designer's role is to propose an innovative approach based on the interaction between scientists and citizens. The chosen end-users are three Natural Regional Parks located in the South West of France. The latter parks are administrative entities which gather municipalities having a common natural and cultural heritage. They are also rural areas in which specific economic activities take place, and therefore are concerned and involved in both protecting their environment and setting-up sustainable economic development. The first year of the project has been dedicated to investigation including the questioning of relevant representatives. Three key local economic sectors have been selected: i.e. forestry, pastoral farming and building activities. Working groups were composed of technicians, administrative and maintenance staff, policy makers and climate researchers. The sectors' needs for climate information have been assessed. The lessons learned led to actions which are presented hereinafter.

  1. Reflections on the Adaptive Designs Accelerating Promising Trials Into Treatments (ADAPT-IT) Process—Findings from a Qualitative Study

    PubMed Central

    Guetterman, Timothy C.; Fetters, Michael D.; Legocki, Laurie J.; Mawocha, Samkeliso; Barsan, William G.; Lewis, Roger J.; Berry, Donald A.; Meurer, William J.

    2015-01-01

    Context The context for this study was the Adaptive Designs Advancing Promising Treatments Into Trials (ADAPT-IT) project, which aimed to incorporate flexible adaptive designs into pivotal clinical trials and to conduct an assessment of the trial development process. Little research provides guidance to academic institutions in planning adaptive trials. Objectives The purpose of this qualitative study was to explore the perspectives and experiences of stakeholders as they reflected back about the interactive ADAPT-IT adaptive design development process, and to understand their perspectives regarding lessons learned about the design of the trials and trial development. Materials and methods We conducted semi-structured interviews with ten key stakeholders and observations of the process. We employed qualitative thematic text data analysis to reduce the data into themes about the ADAPT-IT project and adaptive clinical trials. Results The qualitative analysis revealed four themes: education of the project participants, how the process evolved with participant feedback, procedures that could enhance the development of other trials, and education of the broader research community. Discussion and conclusions While participants became more likely to consider flexible adaptive designs, additional education is needed to both understand the adaptive methodology and articulate it when planning trials. PMID:26622163

  2. Low frequency ac waveform generator

    DOEpatents

    Bilharz, O.W.

    1983-11-22

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stablization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  3. Optimal design of an unsupervised adaptive classifier with unknown priors

    NASA Technical Reports Server (NTRS)

    Kazakos, D.

    1974-01-01

    An adaptive detection scheme for M hypotheses was analyzed. It was assumed that the probability density function under each hypothesis was known, and that the prior probabilities of the M hypotheses were unknown and sequentially estimated. Each observation vector was classified using the current estimate of the prior probabilities. Using a set of nonlinear transformations, and applying stochastic approximation theory, an optimally converging adaptive detection and estimation scheme was designed. The optimality of the scheme lies in the fact that convergence to the true prior probabilities is ensured, and that the asymptotic error variance is minimum, for the class of nonlinear transformations considered. An expression for the asymptotic mean square error variance of the scheme was also obtained.

  4. Adaptive designs undertaken in clinical research: a review of registered clinical trials.

    PubMed

    Hatfield, Isabella; Allison, Annabel; Flight, Laura; Julious, Steven A; Dimairo, Munyaradzi

    2016-03-19

    Adaptive designs have the potential to improve efficiency in the evaluation of new medical treatments in comparison to traditional fixed sample size designs. However, they are still not widely used in practice in clinical research. Little research has been conducted to investigate what adaptive designs are being undertaken. This review highlights the current state of registered adaptive designs and their characteristics. The review looked at phase II, II/III and III trials registered on ClinicalTrials.gov from 29 February 2000 to 1 June 2014, supplemented with trials from the National Institute for Health Research register and known adaptive trials. A range of adaptive design search terms were applied to the trials extracted from each database. Characteristics of the adaptive designs were then recorded including funder, therapeutic area and type of adaptation. The results in the paper suggest that the use of adaptive designs has increased. They seem to be most often used in phase II trials and in oncology. In phase III trials, the most popular form of adaptation is the group sequential design. The review failed to capture all trials with adaptive designs, which suggests that the reporting of adaptive designs, such as in clinical trials registers, needs much improving. We recommend that clinical trial registers should contain sections dedicated to the type and scope of the adaptation and that the term 'adaptive design' should be included in the trial title or at least in the brief summary or design sections.

  5. ECCM Waveform Investigation

    DTIC Science & Technology

    1977-08-01

    For either target model and fixed trans - mit energy, the radar performance decreases as bandwidth increases. The performance decrease with bandwidth...Active Jamming From a radar waveform viewpoint, the wideband barrage jamming environment Is essentially Identical to the thermal noise...nificant radar energy is detected. A quantitative measure of the improvement achievable by wideband techniques is obtained by considering the case

  6. An Overview of the Adaptive Designs Accelerating Promising Trials Into Treatments (ADAPT-IT) Project

    PubMed Central

    Meurer, William J.; Lewis, Roger J.; Tagle, Danilo; Fetters, Michael D; Legocki, Laurie; Berry, Scott; Connor, Jason; Durkalski, Valerie; Elm, Jordan; Zhao, Wenle; Frederiksen, Shirley; Silbergleit, Robert; Palesch, Yuko; Berry, Donald A.; Barsan, William G.

    2013-01-01

    Randomized clinical trials, which aim to determine the efficacy and safety of drugs and medical devices, are a complex enterprise with myriad challenges, stakeholders, and traditions. While the primary goal is scientific discovery, clinical trials must also fulfill regulatory, clinical, and ethical requirements. Innovations in clinical trials methodology have the potential to improve the quality of knowledge gained from trials, the protection of human subjects, and the efficiency of clinical research. Adaptive clinical trial (ACT) methods represent a broad category of innovations intended to address a variety of long-standing challenges faced by investigators, such as sensitivity to prior assumptions and delayed identification of ineffective treatments. The implementation of ACT methods, however, requires greater planning and simulation compared to a more traditional design, along with more advanced administrative infrastructure for trial execution. The value of ACT methods in exploratory phase (phase II) clinical research is generally well accepted, but the potential value and challenges of applying ACT methods in large confirmatory phase clinical trials is relatively unexplored, particularly in the academic setting. In the Adaptive Designs Accelerating Promising Trials Into Treatments (ADAPT-IT) project, a multidisciplinary team is studying how ACT methods could be implemented in planning actual confirmatory phase trials in an established, NIH funded clinical trials network. The overarching objectives of ADAPT-IT are to identify and quantitatively characterize the ACT methods of greatest potential value in confirmatory phase clinical trials, and to elicit and understand the enthusiasms and concerns of key stakeholders that influence their willingness to try these innovative strategies. PMID:22424650

  7. Analog device simulates physiological waveforms

    NASA Technical Reports Server (NTRS)

    Hickman, D. M.

    1964-01-01

    An analog physiological simulator generates representative waveforms for a wide range of physiological conditions. Direct comparison of these waveforms with those from telemetric inputs permits quick detection of signal parameter degradation.

  8. Design of Sequentially Randomized Trials for Testing Adaptive Treatment Strategies

    PubMed Central

    Ogbagaber, Semhar B.; Karp, Jordan; Wahed, Abdus S.

    2016-01-01

    An adaptive treatment strategy (ATS) is an outcome-guided algorithm that allows personalized treatment of complex diseases based on patients’ disease status and treatment history. Conditions such as AIDS, depression, and cancer usually require several stages of treatment due to the chronic, multifactorial nature of illness progression and management. Sequential multiple assignment randomized (SMAR) designs permit simultaneous inference about multiple ATSs, where patients are sequentially randomized to treatments at different stages depending upon response status. The purpose of the article is to develop a sample size formula to ensure adequate power for comparing two or more ATSs. Based on a Wald-type statistic for comparing multiple ATSs with a continuous endpoint, we develop a sample size formula and test it through simulation studies. We show via simulation that the proposed sample size formula maintains the nominal power. The proposed sample size formula is not applicable to designs with time-to-event endpoints but the formula will be useful for practitioners while designing SMAR trials to compare adaptive treatment strategies. PMID:26412033

  9. Optimal Pid Controller Design Using Adaptive Vurpso Algorithm

    NASA Astrophysics Data System (ADS)

    Zirkohi, Majid Moradi

    2015-04-01

    The purpose of this paper is to improve theVelocity Update Relaxation Particle Swarm Optimization algorithm (VURPSO). The improved algorithm is called Adaptive VURPSO (AVURPSO) algorithm. Then, an optimal design of a Proportional-Integral-Derivative (PID) controller is obtained using the AVURPSO algorithm. An adaptive momentum factor is used to regulate a trade-off between the global and the local exploration abilities in the proposed algorithm. This operation helps the system to reach the optimal solution quickly and saves the computation time. Comparisons on the optimal PID controller design confirm the superiority of AVURPSO algorithm to the optimization algorithms mentioned in this paper namely the VURPSO algorithm, the Ant Colony algorithm, and the conventional approach. Comparisons on the speed of convergence confirm that the proposed algorithm has a faster convergence in a less computation time to yield a global optimum value. The proposed AVURPSO can be used in the diverse areas of optimization problems such as industrial planning, resource allocation, scheduling, decision making, pattern recognition and machine learning. The proposed AVURPSO algorithm is efficiently used to design an optimal PID controller.

  10. Platform for Postprocessing Waveform-Based NDE

    NASA Technical Reports Server (NTRS)

    Roth, Don

    2008-01-01

    Taking advantage of the similarities that exist among all waveform-based non-destructive evaluation (NDE) methods, a common software platform has been developed containing multiple- signal and image-processing techniques for waveforms and images. The NASA NDE Signal and Image Processing software has been developed using the latest versions of LabVIEW, and its associated Advanced Signal Processing and Vision Toolkits. The software is useable on a PC with Windows XP and Windows Vista. The software has been designed with a commercial grade interface in which two main windows, Waveform Window and Image Window, are displayed if the user chooses a waveform file to display. Within these two main windows, most actions are chosen through logically conceived run-time menus. The Waveform Window has plots for both the raw time-domain waves and their frequency- domain transformations (fast Fourier transform and power spectral density). The Image Window shows the C-scan image formed from information of the time-domain waveform (such as peak amplitude) or its frequency-domain transformation at each scan location. The user also has the ability to open an image, or series of images, or a simple set of X-Y paired data set in text format. Each of the Waveform and Image Windows contains menus from which to perform many user actions. An option exists to use raw waves obtained directly from scan, or waves after deconvolution if system wave response is provided. Two types of deconvolution, time-based subtraction or inverse-filter, can be performed to arrive at a deconvolved wave set. Additionally, the menu on the Waveform Window allows preprocessing of waveforms prior to image formation, scaling and display of waveforms, formation of different types of images (including non-standard types such as velocity), gating of portions of waves prior to image formation, and several other miscellaneous and specialized operations. The menu available on the Image Window allows many further image

  11. An Adaptive Hybrid Genetic Algorithm for Improved Groundwater Remediation Design

    NASA Astrophysics Data System (ADS)

    Espinoza, F. P.; Minsker, B. S.; Goldberg, D. E.

    2001-12-01

    Identifying optimal designs for a groundwater remediation system is computationally intensive, especially for complex, nonlinear problems such as enhanced in situ bioremediation technology. To improve performance, we apply a hybrid genetic algorithm (HGA), which is a two-step solution method: a genetic algorithm (GA) for global search using the entire population and then a local search (LS) to improve search speed for only a few individuals in the population. We implement two types of HGAs: a non-adaptive HGA (NAHGA), whose operations are invariant throughout the run, and a self-adaptive HGA (SAHGA), whose operations adapt to the performance of the algorithm. The best settings of the two HGAs for optimal performance are then investigated for a groundwater remediation problem. The settings include the frequency of LS with respect to the normal GA evaluation, probability of individual selection for LS, evolution criterion for LS (Lamarckian or Baldwinian), and number of local search iterations. A comparison of the algorithms' performance under different settings will be presented.

  12. An adaptive multimeme algorithm for designing HIV multidrug therapies.

    PubMed

    Neri, Ferrante; Toivanen, Jari; Cascella, Giuseppe Leonardo; Ong, Yew-Soon

    2007-01-01

    This paper proposes a period representation for modeling the multidrug HIV therapies and an Adaptive Multimeme Algorithm (AMmA) for designing the optimal therapy. The period representation offers benefits in terms of flexibility and reduction in dimensionality compared to the binary representation. The AMmA is a memetic algorithm which employs a list of three local searchers adaptively activated by an evolutionary framework. These local searchers, having different features according to the exploration logic and the pivot rule, have the role of exploring the decision space from different and complementary perspectives and, thus, assisting the standard evolutionary operators in the optimization process. Furthermore, the AMmA makes use of an adaptation which dynamically sets the algorithmic parameters in order to prevent stagnation and premature convergence. The numerical results demonstrate that the application of the proposed algorithm leads to very efficient medication schedules which quickly stimulate a strong immune response to HIV. The earlier termination of the medication schedule leads to lesser unpleasant side effects for the patient due to strong antiretroviral therapy. A numerical comparison shows that the AMmA is more efficient than three popular metaheuristics. Finally, a statistical test based on the calculation of the tolerance interval confirms the superiority of the AMmA compared to the other methods for the problem under study.

  13. Optical Design for Extremely Large Telescope Adaptive Optics Systems

    SciTech Connect

    Bauman, Brian J.

    2003-01-01

    Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,{bar y} method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method is shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro-electromechanical system (MEMS) to track the LGS light subaperture by

  14. Optical design of the adaptive optics laser guide star system

    SciTech Connect

    Bissinger, H.

    1994-11-15

    The design of an adaptive optics package for the 3 meter Lick telescope is presented. This instrument package includes a 69 actuator deformable mirror and a Hartmann type wavefront sensor operating in the visible wavelength; a quadrant detector for the tip-tile sensor and a tip-tilt mirror to stabilize atmospheric first order tip-tile errors. A high speed computer drives the deformable mirror to achieve near diffraction limited imagery. The different optical components and their individual design constraints are described. motorized stages and diagnostics tools are used to operate and maintain alignment throughout observation time from a remote control room. The expected performance are summarized and actual results of astronomical sources are presented.

  15. Design of infrasound-detection system via adaptive LMSTDE algorithm

    NASA Technical Reports Server (NTRS)

    Khalaf, C. S.; Stoughton, J. W.

    1984-01-01

    A proposed solution to an aviation safety problem is based on passive detection of turbulent weather phenomena through their infrasonic emission. This thesis describes a system design that is adequate for detection and bearing evaluation of infrasounds. An array of four sensors, with the appropriate hardware, is used for the detection part. Bearing evaluation is based on estimates of time delays between sensor outputs. The generalized cross correlation (GCC), as the conventional time-delay estimation (TDE) method, is first reviewed. An adaptive TDE approach, using the least mean square (LMS) algorithm, is then discussed. A comparison between the two techniques is made and the advantages of the adaptive approach are listed. The behavior of the GCC, as a Roth processor, is examined for the anticipated signals. It is shown that the Roth processor has the desired effect of sharpening the peak of the correlation function. It is also shown that the LMSTDE technique is an equivalent implementation of the Roth processor in the time domain. A LMSTDE lead-lag model, with a variable stability coefficient and a convergence criterion, is designed.

  16. Adaptive strategies in designing the simultaneous global drug development program.

    PubMed

    Yuan, Zhilong; Chen, Gang; Huang, Qin

    2016-01-01

    Many methods have been proposed to account for the potential impact of ethnic/regional factors when extrapolating results from multiregional clinical trials (MRCTs) to targeted ethnic (TE) patients, i.e., "bridging." Most of them either focused on TE patients in the MRCT (i.e., internal bridging) or a separate local clinical trial (LCT) (i.e., external bridging). Huang et al. (2012) integrated both bridging concepts in their method for the Simultaneous Global Drug Development Program (SGDDP) which designs both the MRCT and the LCT prospectively and combines patients in both trials by ethnic origin, i.e., TE vs. non-TE (NTE). The weighted Z test was used to combine information from TE and NTE patients to test with statistical rigor whether a new treatment is effective in the TE population. Practically, the MRCT is often completed before the LCT. Thus to increase the power for the SGDDP and/or obtain more informative data in TE patients, we may use the final results from the MRCT to re-evaluate initial assumptions (e.g., effect sizes, variances, weight), and modify the LCT accordingly. We discuss various adaptive strategies for the LCT such as sample size reassessment, population enrichment, endpoint change, and dose adjustment. As an example, we extend a popular adaptive design method to re-estimate the sample size for the LCT, and illustrate it for a normally distributed endpoint.

  17. Multiplexed chirp waveform synthesizer

    DOEpatents

    Dudley, Peter A.; Tise, Bert L.

    2003-09-02

    A synthesizer for generating a desired chirp signal has M parallel channels, where M is an integer greater than 1, each channel including a chirp waveform synthesizer generating at an output a portion of a digital representation of the desired chirp signal; and a multiplexer for multiplexing the M outputs to create a digital representation of the desired chirp signal. Preferably, each channel receives input information that is a function of information representing the desired chirp signal.

  18. A multi-channel waveform digitizer system

    SciTech Connect

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

    1990-04-01

    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.

  19. Synthesis of MBE-4 accelerating waveforms

    SciTech Connect

    Kim, C.H.; Brady, V.O.; Fessenden, T.J.; Judd, D.L.; Laslett, L.J.

    1985-05-01

    An ion induction linac for HIF must operate near the space charge current limit along most of its length. Small errors in the voltages applied to the accelerating gaps can readily produce local unwanted beam bunching and consequent beam loss. Uncompensated space charge forces will generate current loss from longitudinal beam spreading. In the design of the MBE-4 ideal acceleration voltages were developed that assure self-similar amplifying current waveforms at each position along the accelerator. These were approximately synthesized by adding waveforms that can be obtained from realizable electrical pulsers. A code is used to study effects produced by the imperfect synthesis on the longitudinal ion dynamics and beam current waveforms in the presence of space-charge forces.

  20. Design of the Dual Conjugate Adaptive Optics Test-bed

    NASA Astrophysics Data System (ADS)

    Sharf, Inna; Bell, K.; Crampton, D.; Fitzsimmons, J.; Herriot, Glen; Jolissaint, Laurent; Lee, B.; Richardson, H.; van der Kamp, D.; Veran, Jean-Pierre

    In this paper, we describe the Multi-Conjugate Adaptive Optics laboratory test-bed presently under construction at the University of Victoria, Canada. The test-bench will be used to support research in the performance of multi-conjugate adaptive optics, turbulence simulators, laser guide stars and miniaturizing adaptive optics. The main components of the test-bed include two micro-machined deformable mirrors, a tip-tilt mirror, four wavefront sensors, a source simulator, a dual-layer turbulence simulator, as well as computational and control hardware. The paper will describe in detail the opto-mechanical design of the adaptive optics module, the design of the hot-air turbulence generator and the configuration chosen for the source simulator. Below, we present a summary of these aspects of the bench. The optical and mechanical design of the test-bed has been largely driven by the particular choice of the deformable mirrors. These are continuous micro-machined mirrors manufactured by Boston Micromachines Corporation. They have a clear aperture of 3.3 mm and are deformed with 140 actuators arranged in a square grid. Although the mirrors have an open-loop bandwidth of 6.6 KHz, their shape can be updated at a sampling rate of 100 Hz. In our optical design, the mirrors are conjugated at 0km and 10 km in the atmosphere. A planar optical layout was achieved by using four off-axis paraboloids and several folding mirrors. These optics will be mounted on two solid blocks which can be aligned with respect to each other. The wavefront path design accommodates 3 monochromatic guide stars that can be placed at either 90 km or at infinity. The design relies on the natural separation of the beam into 3 parts because of differences in locations of the guide stars in the field of view. In total four wavefront sensors will be procured from Adaptive Optics Associates (AOA) or built in-house: three for the guide stars and the fourth to collect data from the science source output in

  1. Robust Engineering Designs for Infrastructure Adaptation to a Changing Climate

    NASA Astrophysics Data System (ADS)

    Samaras, C.; Cook, L.

    2015-12-01

    Infrastructure systems are expected to be functional, durable and safe over long service lives - 50 to over 100 years. Observations and models of climate science show that greenhouse gas emissions resulting from human activities have changed climate, weather and extreme events. Projections of future changes (albeit with uncertainties caused by inadequacies of current climate/weather models) can be made based on scenarios for future emissions, but actual future emissions are themselves uncertain. Most current engineering standards and practices for infrastructure assume that the probabilities of future extreme climate and weather events will match those of the past. Climate science shows that this assumption is invalid, but is unable, at present, to define these probabilities over the service lives of existing and new infrastructure systems. Engineering designs, plans, and institutions and regulations will need to be adaptable for a range of future conditions (conditions of climate, weather and extreme events, as well as changing societal demands for infrastructure services). For their current and future projects, engineers should: Involve all stakeholders (owners, financers, insurance, regulators, affected public, climate/weather scientists, etc.) in key decisions; Use low regret, adaptive strategies, such as robust decision making and the observational method, comply with relevant standards and regulations, and exceed their requirements where appropriate; Publish design studies and performance/failure investigations to extend the body of knowledge for advancement of practice. The engineering community should conduct observational and modeling research with climate/weather/social scientists and the concerned communities and account rationally for climate change in revised engineering standards and codes. This presentation presents initial research on decisionmaking under uncertainty for climate resilient infrastructure design.

  2. Seismic waveform modeling over cloud

    NASA Astrophysics Data System (ADS)

    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.

  3. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  4. Design of high temperature adaptability cassegrain collimation system

    NASA Astrophysics Data System (ADS)

    Chen, Zhibin; Song, Yan; Liu, Xianhong; Xiao, Wenjian

    2014-12-01

    Collimation system is an indispensable part of the photoelectric detection equipment. Aimed at meeting the demand of field on-line detection for photoelectric system, the system must have higher requirements for its volume, quality and the anti-interference ability of all sorts of complex weather conditions. In order to solve this problem, this paper designed a kind of high temperature adaptability reflex cassegrain collimation system. First the technical indexes of the system was put forward according to the requirements of practical application, then the initial structure parameters was calculated by gaussian optical computing and optimized processing through Zemax. The simulation results showed that the MTF of the system was close to the diffraction limit, which had a good image quality. The system structure tube adopted hard steel material; the primary mirror and secondary mirror used low expansion coefficient of microcrystalline glass, which effectively reduced the deformation due to temperature difference and remained little change in quality and volume at the same time. The experiment results in high and low temperature environments also showed that the collimation system could keep within 30 "beam divergence angle, which proved to have good temperature adaptability, so that it can be used in the field of complex bad conditions.

  5. Adaptive antenna arrays for satellite communications: Design and testing

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.; Swarner, W. G.; Walton, E. K.

    1985-01-01

    When two separate antennas are used with each feedback loop to decorrelate noise, the antennas should be located such that the phase of the interfering signal in the two antennas is the same while the noise in them is uncorrelated. Thus, the antenna patterns and spatial distribution of the auxiliary antennas are quite important and should be carefully selected. The selection and spatial distribution of auxiliary elements is discussed when the main antenna is a center fed reflector antenna. It is shown that offset feeds of the reflector antenna can be used as auxiliary elements of an adaptive array to suppress weak interfering signals. An experimental system is designed to verify the theoretical analysis. The details of the experimental systems are presented.

  6. Wireless thermal sensor network with adaptive low power design.

    PubMed

    Lee, Ho-Yin; Chen, Shih-Lun; Chen, Chiung-An; Huang, Hong-Yi; Luo, Ching-Hsing

    2007-01-01

    There is an increasing need to develop flexible, reconfigurable, and intelligent low power wireless sensor network (WSN) system for healthcare applications. Technical advancements in micro-sensors, MEMS devices, low power electronics, and radio frequency circuits have enabled the design and development of such highly integrated system. In this paper, we present our proposed wireless thermal sensor network system, which is separated into control and data paths. Both of these paths have their own transmission frequencies. The control path sends the power and function commands from computer to each sensor elements by 2.4GHz RF circuits and the data path transmits measured data by 2.4GHz in sensor layer and 60GHz in higher layers. This hierarchy architecture would make reconfigurable mapping and pipeline applications on WSN possibly, and the average power consumption can be efficiently reduced about 60% by using the adaptive technique.

  7. An Approach to Automated Fusion System Design and Adaptation

    PubMed Central

    Fritze, Alexander; Mönks, Uwe; Holst, Christoph-Alexander; Lohweg, Volker

    2017-01-01

    Industrial applications are in transition towards modular and flexible architectures that are capable of self-configuration and -optimisation. This is due to the demand of mass customisation and the increasing complexity of industrial systems. The conversion to modular systems is related to challenges in all disciplines. Consequently, diverse tasks such as information processing, extensive networking, or system monitoring using sensor and information fusion systems need to be reconsidered. The focus of this contribution is on distributed sensor and information fusion systems for system monitoring, which must reflect the increasing flexibility of fusion systems. This contribution thus proposes an approach, which relies on a network of self-descriptive intelligent sensor nodes, for the automatic design and update of sensor and information fusion systems. This article encompasses the fusion system configuration and adaptation as well as communication aspects. Manual interaction with the flexibly changing system is reduced to a minimum. PMID:28300762

  8. Impacting patient outcomes through design: acuity adaptable care/universal room design.

    PubMed

    Brown, Katherine Kay; Gallant, Dennis

    2006-01-01

    To succeed in today's challenging healthcare environment, hospitals must examine their impact on customers--patients and families--staff and physicians. By using competitive facility design and incorporating evidence-based concepts such as the acuity adaptable care delivery model and the universal room, the hospital will realize an impact on patient satisfaction that will enhance market share, on physician satisfaction that will foster loyalty, and on staff satisfaction that will decrease turnover. At the same time, clinical outcomes such as a reduction in mortality and complications and efficiencies such as a reduction in length of stay and minimization of hospital costs through the elimination of transfers can be gained. The results achieved are dependent on the principles used in designing the patient room that should focus on maximizing patient safety and improving healing. This article will review key design elements that support the success of an acuity adaptable unit such as the use of a private room with zones dedicated to patients, families, and staff, healing environment, technology, and decentralized nursing stations that support the success of the acuity adaptable unit. Outcomes of institutions currently utilizing the acuity adaptable concept will be reviewed.

  9. Analysis and design of an adaptive lightweight satellite mirror

    NASA Astrophysics Data System (ADS)

    Duerr, Johannes K.; Honke, Robert; Alberti, Mathias V.; Sippel, Rudolf

    2002-07-01

    Future scientific space missions based on interferometric optical and infrared astronomical instruments are currently under development in the United States as well as in Europe. These instruments require optical path length accuracy in the order of a few nanometers across structural dimensions of several meters. This puts extreme demands on static and dynamic structural stability. It is expected that actively controlled, adaptive structures will increasingly have to be used for these satellite applications to overcome the limits of passive structural accuracy. Based on the evaluation of different piezo-active concepts presented two years ago analysis and design of an adaptive lightweight satellite mirror primarily made of carbon-fiber reinforced plastic with embedded piezoceramic actuators for shape control is being described. Simulation of global mirror performance takes different wavefront-sensors and controls for several cases of loading into account. In addition extensive finite-element optimization of various structural details has been performed. Local material properties of sub-assemblies or geometry effects at the edges of the structure are investigated with respect to their impact on mirror performance. One important result of the analysis was the lay-out of actuator arrays consisting of specifically designed and custom made piezoceramic actuators. Prototype manufacturing and testing of active sub-components is described in detail. The results obtained served as a basis for a final update of finite-element models. The paper concludes with an outline on manufacturing, testing, and space qualification of the prototype demonstrator of an actively controllable lightweight satellite mirror currently under way. The research work presented in this paper is part of the German industrial research project 'ADAPTRONIK'.

  10. Design, realization and structural testing of a compliant adaptable wing

    NASA Astrophysics Data System (ADS)

    Molinari, G.; Quack, M.; Arrieta, A. F.; Morari, M.; Ermanni, P.

    2015-10-01

    This paper presents the design, optimization, realization and testing of a novel wing morphing concept, based on distributed compliance structures, and actuated by piezoelectric elements. The adaptive wing features ribs with a selectively compliant inner structure, numerically optimized to achieve aerodynamically efficient shape changes while simultaneously withstanding aeroelastic loads. The static and dynamic aeroelastic behavior of the wing, and the effect of activating the actuators, is assessed by means of coupled 3D aerodynamic and structural simulations. To demonstrate the capabilities of the proposed morphing concept and optimization procedure, the wings of a model airplane are designed and manufactured according to the presented approach. The goal is to replace conventional ailerons, thus to achieve controllability in roll purely by morphing. The mechanical properties of the manufactured components are characterized experimentally, and used to create a refined and correlated finite element model. The overall stiffness, strength, and actuation capabilities are experimentally tested and successfully compared with the numerical prediction. To counteract the nonlinear hysteretic behavior of the piezoelectric actuators, a closed-loop controller is implemented, and its capability of accurately achieving the desired shape adaptation is evaluated experimentally. Using the correlated finite element model, the aeroelastic behavior of the manufactured wing is simulated, showing that the morphing concept can provide sufficient roll authority to allow controllability of the flight. The additional degrees of freedom offered by morphing can be also used to vary the plane lift coefficient, similarly to conventional flaps. The efficiency improvements offered by this technique are evaluated numerically, and compared to the performance of a rigid wing.

  11. Full waveform inversion for ultrasonic flaw identification

    NASA Astrophysics Data System (ADS)

    Seidl, Robert; Rank, Ernst

    2017-02-01

    Ultrasonic Nondestructive Testing is concerned with detecting flaws inside components without causing physical damage. It is possible to detect flaws using ultrasound measurements but usually no additional details about the flaw like position, dimension or orientation are available. The information about these details is hidden in the recorded experimental signals. The idea of full waveform inversion is to adapt the parameters of an initial simulation model of the undamaged specimen by minimizing the discrepancy between these simulated signals and experimentally measured signals of the flawed specimen. Flaws in the structure are characterized by a change or deterioration in the material properties. Commonly, full waveform inversion is mostly applied in seismology on a larger scale to infer mechanical properties of the earth. We propose to use acoustic full waveform inversion for structural parameters to visualize the interior of the component. The method is adapted to US NDT by combining multiple similar experiments on the test component as the typical small amount of sensors is not sufficient for a successful imaging. It is shown that the combination of simulations and multiple experiments can be used to detect flaws and their position, dimension and orientation in emulated simulation cases.

  12. High precision triangular waveform generator

    DOEpatents

    Mueller, Theodore R.

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  13. Solution-verified reliability analysis and design of bistable MEMS using error estimation and adaptivity.

    SciTech Connect

    Eldred, Michael Scott; Subia, Samuel Ramirez; Neckels, David; Hopkins, Matthew Morgan; Notz, Patrick K.; Adams, Brian M.; Carnes, Brian; Wittwer, Jonathan W.; Bichon, Barron J.; Copps, Kevin D.

    2006-10-01

    This report documents the results for an FY06 ASC Algorithms Level 2 milestone combining error estimation and adaptivity, uncertainty quantification, and probabilistic design capabilities applied to the analysis and design of bistable MEMS. Through the use of error estimation and adaptive mesh refinement, solution verification can be performed in an automated and parameter-adaptive manner. The resulting uncertainty analysis and probabilistic design studies are shown to be more accurate, efficient, reliable, and convenient.

  14. Assessing Accuracy of Waveform Models against Numerical Relativity Waveforms

    NASA Astrophysics Data System (ADS)

    Pürrer, Michael; LVC Collaboration

    2016-03-01

    We compare currently available phenomenological and effective-one-body inspiral-merger-ringdown models for gravitational waves (GW) emitted from coalescing black hole binaries against a set of numerical relativity waveforms from the SXS collaboration. Simplifications are used in the construction of some waveform models, such as restriction to spins aligned with the orbital angular momentum, no inclusion of higher harmonics in the GW radiation, no modeling of eccentricity and the use of effective parameters to describe spin precession. In contrast, NR waveforms provide us with a high fidelity representation of the ``true'' waveform modulo small numerical errors. To focus on systematics we inject NR waveforms into zero noise for early advanced LIGO detector sensitivity at a moderately optimistic signal-to-noise ratio. We discuss where in the parameter space the above modeling assumptions lead to noticeable biases in recovered parameters.

  15. Current Practice in Designing Training for Complex Skills: Implications for Design and Evaluation of ADAPT[IT].

    ERIC Educational Resources Information Center

    Eseryel, Deniz; Schuver-van Blanken, Marian J.; Spector, J. Michael

    ADAPT[IT] (Advanced Design Approach for Personalized Training-Interactive Tools is a European project coordinated by the Dutch National Aerospace Laboratory. The aim of ADAPT[IT] is to create and validate an effective training design methodology, based on cognitive science and leading to the integration of advanced technologies, so that the…

  16. Adaptive filter design using recurrent cerebellar model articulation controller.

    PubMed

    Lin, Chih-Min; Chen, Li-Yang; Yeung, Daniel S

    2010-07-01

    A novel adaptive filter is proposed using a recurrent cerebellar-model-articulation-controller (CMAC). The proposed locally recurrent globally feedforward recurrent CMAC (RCMAC) has favorable properties of small size, good generalization, rapid learning, and dynamic response, thus it is more suitable for high-speed signal processing. To provide fast training, an efficient parameter learning algorithm based on the normalized gradient descent method is presented, in which the learning rates are on-line adapted. Then the Lyapunov function is utilized to derive the conditions of the adaptive learning rates, so the stability of the filtering error can be guaranteed. To demonstrate the performance of the proposed adaptive RCMAC filter, it is applied to a nonlinear channel equalization system and an adaptive noise cancelation system. The advantages of the proposed filter over other adaptive filters are verified through simulations.

  17. Accelerated search for materials with targeted properties by adaptive design

    PubMed Central

    Xue, Dezhen; Balachandran, Prasanna V.; Hogden, John; Theiler, James; Xue, Deqing; Lookman, Turab

    2016-01-01

    Finding new materials with targeted properties has traditionally been guided by intuition, and trial and error. With increasing chemical complexity, the combinatorial possibilities are too large for an Edisonian approach to be practical. Here we show how an adaptive design strategy, tightly coupled with experiments, can accelerate the discovery process by sequentially identifying the next experiments or calculations, to effectively navigate the complex search space. Our strategy uses inference and global optimization to balance the trade-off between exploitation and exploration of the search space. We demonstrate this by finding very low thermal hysteresis (ΔT) NiTi-based shape memory alloys, with Ti50.0Ni46.7Cu0.8Fe2.3Pd0.2 possessing the smallest ΔT (1.84 K). We synthesize and characterize 36 predicted compositions (9 feedback loops) from a potential space of ∼800,000 compositions. Of these, 14 had smaller ΔT than any of the 22 in the original data set. PMID:27079901

  18. Designing for Change: Interoperability in a scaling and adapting environment

    NASA Astrophysics Data System (ADS)

    Yarmey, L.

    2015-12-01

    The Earth Science cyberinfrastructure landscape is constantly changing. Technologies advance and technical implementations are refined or replaced. Data types, volumes, packaging, and use cases evolve. Scientific requirements emerge and mature. Standards shift while systems scale and adapt. In this complex and dynamic environment, interoperability remains a critical component of successful cyberinfrastructure. Through the resource- and priority-driven iterations on systems, interfaces, and content, questions fundamental to stable and useful Earth Science cyberinfrastructure arise. For instance, how are sociotechnical changes planned, tracked, and communicated? How should operational stability balance against 'new and shiny'? How can ongoing maintenance and mitigation of technical debt be managed in an often short-term resource environment? The Arctic Data Explorer is a metadata brokering application developed to enable discovery of international, interdisciplinary Arctic data across distributed repositories. Completely dependent on interoperable third party systems, the Arctic Data Explorer publicly launched in 2013 with an original 3000+ data records from four Arctic repositories. Since then the search has scaled to 25,000+ data records from thirteen repositories at the time of writing. In the final months of original project funding, priorities shift to lean operations with a strategic eye on the future. Here we present lessons learned from four years of Arctic Data Explorer design, development, communication, and maintenance work along with remaining questions and potential directions.

  19. Optical Design and Optimization of Translational Reflective Adaptive Optics Ophthalmoscopes

    NASA Astrophysics Data System (ADS)

    Sulai, Yusufu N. B.

    The retina serves as the primary detector for the biological camera that is the eye. It is composed of numerous classes of neurons and support cells that work together to capture and process an image formed by the eye's optics, which is then transmitted to the brain. Loss of sight due to retinal or neuro-ophthalmic disease can prove devastating to one's quality of life, and the ability to examine the retina in vivo is invaluable in the early detection and monitoring of such diseases. Adaptive optics (AO) ophthalmoscopy is a promising diagnostic tool in early stages of development, still facing significant challenges before it can become a clinical tool. The work in this thesis is a collection of projects with the overarching goal of broadening the scope and applicability of this technology. We begin by providing an optical design approach for AO ophthalmoscopes that reduces the aberrations that degrade the performance of the AO correction. Next, we demonstrate how to further improve image resolution through the use of amplitude pupil apodization and non-common path aberration correction. This is followed by the development of a viewfinder which provides a larger field of view for retinal navigation. Finally, we conclude with the development of an innovative non-confocal light detection scheme which improves the non-invasive visualization of retinal vasculature and reveals the cone photoreceptor inner segments in healthy and diseased eyes.

  20. Designing Adaptive Instructional Environments: Insights from Empirical Evidence

    DTIC Science & Technology

    2011-10-01

    Similarly, Shute and Zapata -Rivera (2008) define adaptivity as the capability of a system to alter its behavior according to learner needs and...60(2), 265-306. Landsberg, C R., Van Buskirk, W. L., Astwood Jr., R. A., Mercado , A. D., & Aakre, A. J. (2010). Adaptive training considerations...22, 77-92. Shute, V. J., & Zapata -Rivera, D. (2008). Adaptive technologies. In J. M. Spector, M. D. Merril, J. J. G. van Merriënboer, & M. Driscoll

  1. Waveform Sampler CAMAC Module

    SciTech Connect

    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 ..mu..s conversion time and stored in an on-board memory accessible through CAMAC.

  2. Case Studies in Computer Adaptive Test Design through Simulation.

    ERIC Educational Resources Information Center

    Eignor, Daniel R.; And Others

    The extensive computer simulation work done in developing the computer adaptive versions of the Graduate Record Examinations (GRE) Board General Test and the College Board Admissions Testing Program (ATP) Scholastic Aptitude Test (SAT) is described in this report. Both the GRE General and SAT computer adaptive tests (CATs), which are fixed length…

  3. Time domain and frequency domain design techniques for model reference adaptive control systems

    NASA Technical Reports Server (NTRS)

    Boland, J. S., III

    1971-01-01

    Some problems associated with the design of model-reference adaptive control systems are considered and solutions to these problems are advanced. The stability of the adapted system is a primary consideration in the development of both the time-domain and the frequency-domain design techniques. Consequentially, the use of Liapunov's direct method forms an integral part of the derivation of the design procedures. The application of sensitivity coefficients to the design of model-reference adaptive control systems is considered. An application of the design techniques is also presented.

  4. An adaptive optics imaging system designed for clinical use.

    PubMed

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R; Rossi, Ethan A

    2015-06-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2-3 arc minutes, (arcmin) 2) ~0.5-0.8 arcmin and, 3) ~0.05-0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3-5 arcmin, 2) ~0.7-1.1 arcmin and 3) ~0.07-0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing.

  5. An adaptive optics imaging system designed for clinical use

    PubMed Central

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R.; Rossi, Ethan A.

    2015-01-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2–3 arc minutes, (arcmin) 2) ~0.5–0.8 arcmin and, 3) ~0.05–0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3–5 arcmin, 2) ~0.7–1.1 arcmin and 3) ~0.07–0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing. PMID:26114033

  6. Matched filter based iterative adaptive approach

    NASA Astrophysics Data System (ADS)

    Nepal, Ramesh; Zhang, Yan Rockee; Li, Zhengzheng; Blake, William

    2016-05-01

    Matched Filter sidelobes from diversified LPI waveform design and sensor resolution are two important considerations in radars and active sensors in general. Matched Filter sidelobes can potentially mask weaker targets, and low sensor resolution not only causes a high margin of error but also limits sensing in target-rich environment/ sector. The improvement in those factors, in part, concern with the transmitted waveform and consequently pulse compression techniques. An adaptive pulse compression algorithm is hence desired that can mitigate the aforementioned limitations. A new Matched Filter based Iterative Adaptive Approach, MF-IAA, as an extension to traditional Iterative Adaptive Approach, IAA, has been developed. MF-IAA takes its input as the Matched Filter output. The motivation here is to facilitate implementation of Iterative Adaptive Approach without disrupting the processing chain of traditional Matched Filter. Similar to IAA, MF-IAA is a user parameter free, iterative, weighted least square based spectral identification algorithm. This work focuses on the implementation of MF-IAA. The feasibility of MF-IAA is studied using a realistic airborne radar simulator as well as actual measured airborne radar data. The performance of MF-IAA is measured with different test waveforms, and different Signal-to-Noise (SNR) levels. In addition, Range-Doppler super-resolution using MF-IAA is investigated. Sidelobe reduction as well as super-resolution enhancement is validated. The robustness of MF-IAA with respect to different LPI waveforms and SNR levels is also demonstrated.

  7. Signal waveform detection with statistical automaton for internet and web service streaming.

    PubMed

    Tseng, Kuo-Kun; Ji, Yuzhu; Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying

    2014-01-01

    In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.

  8. Signal Waveform Detection with Statistical Automaton for Internet and Web Service Streaming

    PubMed Central

    Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying

    2014-01-01

    In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment. PMID:25032231

  9. Use of experimental design to optimize a triple-potential waveform to develop a method for the determination of streptomycin and dihydrostreptomycin in pharmaceutical veterinary dosage forms by HPLC-PAD.

    PubMed

    Martínez-Mejía, Mónica J; Rath, Susanne

    2015-02-01

    An HPLC-PAD method using a gold working electrode and a triple-potential waveform was developed for the simultaneous determination of streptomycin and dihydrostreptomycin in veterinary drugs. Glucose was used as the internal standard, and the triple-potential waveform was optimized using a factorial and a central composite design. The optimum potentials were as follows: amperometric detection, E1=-0.15V; cleaning potential, E2=+0.85V; and reactivation of the electrode surface, E3=-0.65V. For the separation of the aminoglycosides and the internal standard of glucose, a CarboPac™ PA1 anion exchange column was used together with a mobile phase consisting of a 0.070 mol L(-1) sodium hydroxide solution in the isocratic elution mode with a flow rate of 0.8 mL min(-1). The method was validated and applied to the determination of streptomycin and dihydrostreptomycin in veterinary formulations (injection, suspension and ointment) without any previous sample pretreatment, except for the ointments, for which a liquid-liquid extraction was required before HPLC-PAD analysis. The method showed adequate selectivity, with an accuracy of 98-107% and a precision of less than 3.9%.

  10. Adaptive design clinical trials and trial logistics models in CNS drug development.

    PubMed

    Wang, Sue-Jane; Hung, H M James; O'Neill, Robert

    2011-02-01

    In central nervous system therapeutic areas, there are general concerns with establishing efficacy thought to be sources of high attrition rate in drug development. For instance, efficacy endpoints are often subjective and highly variable. There is a lack of robust or operational biomarkers to substitute for soft endpoints. In addition, animal models are generally poor, unreliable or unpredictive. To increase the probability of success in central nervous system drug development program, adaptive design has been considered as an alternative designs that provides flexibility to the conventional fixed designs and has been viewed to have the potential to improve the efficiency in drug development processes. In addition, successful implementation of an adaptive design trial relies on establishment of a trustworthy logistics model that ensures integrity of the trial conduct. In accordance with the spirit of the U.S. Food and Drug Administration adaptive design draft guidance document recently released, this paper enlists the critical considerations from both methodological aspects and regulatory aspects in reviewing an adaptive design proposal and discusses two general types of adaptations, sample size planning and re-estimation, and two-stage adaptive design. Literature examples of adaptive designs in central nervous system are used to highlight the principles laid out in the U.S. FDA draft guidance. Four logistics models seen in regulatory adaptive design applications are introduced. In general, complex adaptive designs require simulation studies to access the design performance. For an adequate and well-controlled clinical trial, if a Learn-and-Confirm adaptive selection approach is considered, the study-wise type I error rate should be adhered to. However, it is controversial to use the simulated type I error rate to address a strong control of the study-wise type I error rate.

  11. Time domain reflectometry waveform analysis with second order bounded mean oscillation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tangent-line methods and adaptive waveform interpretation with Gaussian filtering (AWIGF) have been proposed for determining reflection positions of time domain reflectometry (TDR) waveforms. However, the accuracy of those methods is limited for short probe TDR sensors. Second order bounded mean osc...

  12. Optimal current waveforms for brushless permanent magnet motors

    NASA Astrophysics Data System (ADS)

    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.

  13. Issues and Challenges in the Design of Culturally Adapted Evidence-Based Interventions

    PubMed Central

    Castro, Felipe González; Barrera, Manuel; Holleran Steiker, Lori K.

    2014-01-01

    This article examines issues and challenges in the design of cultural adaptations that are developed from an original evidence-based intervention (EBI). Recently emerging multistep frameworks or stage models are examined, as these can systematically guide the development of culturally adapted EBIs. Critical issues are also presented regarding whether and how such adaptations may be conducted, and empirical evidence is presented regarding the effectiveness of such cultural adaptations. Recent evidence suggests that these cultural adaptations are effective when applied with certain subcultural groups, although they are less effective when applied with other subcultural groups. Generally, current evidence regarding the effectiveness of cultural adaptations is promising but mixed. Further research is needed to obtain more definitive conclusions regarding the efficacy and effectiveness of culturally adapted EBIs. Directions for future research and recommendations are presented to guide the development of a new generation of culturally adapted EBIs. PMID:20192800

  14. Bayesian optimal response-adaptive design for binary responses using stopping rule.

    PubMed

    Komaki, Fumiyasu; Biswas, Atanu

    2016-05-02

    Response-adaptive designs are used in phase III clinical trials to allocate a larger number of patients to the better treatment arm. Optimal designs are explored in the recent years in the context of response-adaptive designs, in the frequentist view point only. In the present paper, we propose some response-adaptive designs for two treatments based on Bayesian prediction for phase III clinical trials. Some properties are studied and numerically compared with some existing competitors. A real data set is used to illustrate the applicability of the proposed methodology where we redesign the experiment using parameters derived from the data set.

  15. Adapting Dam and Reservoir Design and Operations to Climate Change

    NASA Astrophysics Data System (ADS)

    Roy, René; Braun, Marco; Chaumont, Diane

    2013-04-01

    In order to identify the potential initiatives that the dam, reservoir and water resources systems owners and operators may undertake to cope with climate change issues, it is essential to determine the current state of knowledge of their impacts on hydrological variables at regional and local scales. Future climate scenarios derived from climate model simulations can be combined with operational hydrological modeling tools and historical observations to evaluate realistic pathways of future hydrological conditions for specific drainage basins. In the case of hydropower production those changes in hydrological conditions may have significant economic impacts. For over a decade the state owned hydropower producer Hydro Québec has been exploring the physical impacts on their watersheds by relying on climate services in collaboration with Ouranos, a consortium on regional climatology and adaptation to climate change. Previous climate change impact analysis had been including different sources of climate simulation data, explored different post-processing approaches and used hydrological impact models. At a new stage of this collaboration the operational management of Hydro Quebec aspired to carry out a cost-benefit analysis of considering climate change in the refactoring of hydro-power installations. In the process of the project not only a set of scenarios of future runoff regimes had to be defined to support long term planning decisions of a dam and reservoir operator, but also the significance of uncertainties needed to be communicated and made understood. We provide insight into a case study that took some unexpected turns and leaps by bringing together climate scientists, hydrologists and hydro-power operation managers. The study includes the selection of appropriate climate scenarios, the correction of biases, the application of hydrological models and the assessment of uncertainties. However, it turned out that communicating the science properly and

  16. An Automatic Online Calibration Design in Adaptive Testing

    ERIC Educational Resources Information Center

    Makransky, Guido; Glas, Cees A. W.

    2010-01-01

    An accurately calibrated item bank is essential for a valid computerized adaptive test. However, in some settings, such as occupational testing, there is limited access to test takers for calibration. As a result of the limited access to possible test takers, collecting data to accurately calibrate an item bank in an occupational setting is…

  17. Evolving RBF neural networks for adaptive soft-sensor design.

    PubMed

    Alexandridis, Alex

    2013-12-01

    This work presents an adaptive framework for building soft-sensors based on radial basis function (RBF) neural network models. The adaptive fuzzy means algorithm is utilized in order to evolve an RBF network, which approximates the unknown system based on input-output data from it. The methodology gradually builds the RBF network model, based on two separate levels of adaptation: On the first level, the structure of the hidden layer is modified by adding or deleting RBF centers, while on the second level, the synaptic weights are adjusted with the recursive least squares with exponential forgetting algorithm. The proposed approach is tested on two different systems, namely a simulated nonlinear DC Motor and a real industrial reactor. The results show that the produced soft-sensors can be successfully applied to model the two nonlinear systems. A comparison with two different adaptive modeling techniques, namely a dynamic evolving neural-fuzzy inference system (DENFIS) and neural networks trained with online backpropagation, highlights the advantages of the proposed methodology.

  18. Context-Adaptive Learning Designs by Using Semantic Web Services

    ERIC Educational Resources Information Center

    Dietze, Stefan; Gugliotta, Alessio; Domingue, John

    2007-01-01

    IMS Learning Design (IMS-LD) is a promising technology aimed at supporting learning processes. IMS-LD packages contain the learning process metadata as well as the learning resources. However, the allocation of resources--whether data or services--within the learning design is done manually at design-time on the basis of the subjective appraisals…

  19. Focal waveforms for various source waveforms driving a prolate-spheroidal impulse radiating antenna (IRA)

    NASA Astrophysics Data System (ADS)

    Altunc, Serhat; Baum, Carl E.; Christodoulou, Christos G.; Schamiloglu, Edl; Buchenauer, C. Jerald

    2008-08-01

    Impulse radiating antennas (IRAs) are designed to radiate very fast pulses in a narrow beam with low dispersion and high field amplitude. For this reason they have been used in a variety of applications. IRAs have been developed for use in the transient far-field region using parabolic reflectors. However, in this paper we focus in the near field region and develop the field waveform at the second focus of a prolate-spheroidal IRA. Certain skin cancers can be killed by the application of a high-amplitude electric field pulse. This can be accomplished by either inserting electrodes near the skin cancer or by applying fast, high-electric field pulses without direct contact. We investigate a new manifestation of an IRA, in which we use a prolate spheroid as a reflector instead of a parabolic reflector and focus in the near-field region instead of the far-field region. This technique minimizes skin damage associated with inserting electrodes near the tumor. Analytical and experimental behaviors for the focal waveforms of two and four-feed arm prolate-spheroidal IRAs are explored. With appropriate choice of the driving waveform we maximize the impulse field at the second focus. The focal waveform of a prolate-spheroidal IRA has been explained theoretically and verified experimentally.

  20. Decentralized adaptive control of robot manipulators with robust stabilization design

    NASA Technical Reports Server (NTRS)

    Yuan, Bau-San; Book, Wayne J.

    1988-01-01

    Due to geometric nonlinearities and complex dynamics, a decentralized technique for adaptive control for multilink robot arms is attractive. Lyapunov-function theory for stability analysis provides an approach to robust stabilization. Each joint of the arm is treated as a component subsystem. The adaptive controller is made locally stable with servo signals including proportional and integral gains. This results in the bound on the dynamical interactions with other subsystems. A nonlinear controller which stabilizes the system with uniform boundedness is used to improve the robustness properties of the overall system. As a result, the robot tracks the reference trajectories with convergence. This strategy makes computation simple and therefore facilitates real-time implementation.

  1. A Web-Based Adaptive Tutor to Teach PCR Primer Design

    ERIC Educational Resources Information Center

    van Seters, Janneke R.; Wellink, Joan; Tramper, Johannes; Goedhart, Martin J.; Ossevoort, Miriam A.

    2012-01-01

    When students have varying prior knowledge, personalized instruction is desirable. One way to personalize instruction is by using adaptive e-learning to offer training of varying complexity. In this study, we developed a web-based adaptive tutor to teach PCR primer design: the PCR Tutor. We used part of the Taxonomy of Educational Objectives (the…

  2. Towards Individualized Online Learning: The Design and Development of an Adaptive Web Based Learning Environment

    ERIC Educational Resources Information Center

    Inan, Fethi A.; Flores, Raymond; Ari, Fatih; Arslan-Ari, Ismahan

    2011-01-01

    The purpose of this study was to document the design and development of an adaptive system which individualizes instruction such as content, interfaces, instructional strategies, and resources dependent on two factors, namely student motivation and prior knowledge levels. Combining adaptive hypermedia methods with strategies proposed by…

  3. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  4. ADAPT: A knowledge-based synthesis tool for digital signal processing system design

    SciTech Connect

    Cooley, E.S.

    1988-01-01

    A computer aided synthesis tool for expansion, compression, and filtration of digital images is described. ADAPT, the Autonomous Digital Array Programming Tool, uses an extensive design knowledge base to synthesize a digital signal processing (DSP) system. Input to ADAPT can be either a behavioral description in English, or a block level specification via Petri Nets. The output from ADAPT comprises code to implement the DSP system on an array of processors. ADAPT is constructed using C, Prolog, and X Windows on a SUN 3/280 workstation. ADAPT knowledge encompasses DSP component information and the design algorithms and heuristics of a competent DSP designer. The knowledge is used to form queries for design capture, to generate design constraints from the user's responses, and to examine the design constraints. These constraints direct the search for possible DSP components and target architectures. Constraints are also used for partitioning the target systems into less complex subsystems. The subsystems correspond to architectural building blocks of the DSP design. These subsystems inherit design constraints and DSP characteristics from their parent blocks. Thus, a DSP subsystem or parent block, as designed by ADAPT, must meet the user's design constraints. Design solutions are sought by searching the Components section of the design knowledge base. Component behavior which matches or is similar to that required by the DSP subsystems is sought. Each match, which corresponds to a design alternative, is evaluated in terms of its behavior. When a design is sufficiently close to the behavior required by the user, detailed mathematical simulations may be performed to accurately determine exact behavior.

  5. Response-Adaptive Decision-Theoretic Trial Design: Operating Characteristics and Ethics

    PubMed Central

    Lipsky, Ari M.; Lewis, Roger J.

    2013-01-01

    Adaptive randomization is used in clinical trials to increase statistical efficiency. In addition, some clinicians and researchers believe that using adaptive randomization leads necessarily to more ethical treatment of subjects in a trial. We develop Bayesian, decision-theoretic, clinical trial designs with response-adaptive randomization and a primary goal of estimating treatment effect, and then contrast these designs with designs that also include in their loss function a cost for poor subject outcome. When the loss function did not incorporate a cost for poor subject outcome, the gains in efficiency from response-adaptive randomization were accompanied by ethically concerning subject allocations. Conversely, including a cost for poor subject outcome demonstrated a more acceptable balance between the competing needs in the trial. A subsequent, parallel set of trials designed to control explicitly type I and II error rates showed that much of the improvement achieved through modification of the loss function was essentially negated. Therefore, gains in efficiency from the use of a decision-theoretic, response-adaptive design using adaptive randomization may only be assumed to apply to those goals which are explicitly included in the loss function. Trial goals, including ethical ones, which do not appear in the loss function are ignored and may even be compromised; it is thus inappropriate to assume that all adaptive trials are necessarily more ethical. Controlling type I and II error rates largely negates the benefit of including competing needs in favor of the goal of parameter estimation. PMID:23558674

  6. Design of fuzzy system by NNs and realization of adaptability

    NASA Technical Reports Server (NTRS)

    Takagi, Hideyuki

    1993-01-01

    The issue of designing and tuning fuzzy membership functions by neural networks (NN's) was started by NN-driven Fuzzy Reasoning in 1988. NN-driven fuzzy reasoning involves a NN embedded in the fuzzy system which generates membership values. In conventional fuzzy system design, the membership functions are hand-crafted by trial and error for each input variable. In contrast, NN-driven fuzzy reasoning considers several variables simultaneously and can design a multidimensional, nonlinear membership function for the entire subspace.

  7. Aircraft conceptual design - an adaptable parametric sizing methodology

    NASA Astrophysics Data System (ADS)

    Coleman, Gary John, Jr.

    Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of mission, configuration and technology to quickly assess first order design and mission sensitivities. During this phase, various missions and technologies are assessed. During this phase, the designer is identifying design solutions of concepts and configurations to meet combinations of mission and technology. This research undertaking contributes the state-of-the-art in aircraft parametric sizing through (1) development of a dedicated conceptual design process and disciplinary methods library, (2) development of a novel and robust parametric sizing process based on 'best-practice' approaches found in the process and disciplinary methods library, and (3) application of the parametric sizing process to a variety of design missions (transonic, supersonic and hypersonic transports), different configurations (tail-aft, blended wing body, strut-braced wing, hypersonic blended bodies, etc.), and different technologies (composite, natural laminar flow, thrust vectored control, etc.), in order to demonstrate the robustness of the methodology and unearth first-order design sensitivities to current and future aerospace design problems. This research undertaking demonstrates the importance of this early design step in selecting the correct combination of mission, technologies and configuration to

  8. Load-Adapted Design of Generative Manufactured Lattice Structures

    NASA Astrophysics Data System (ADS)

    Reinhart, Gunther; Teufelhart, Stefan

    Additive layer manufacturing offers many opportunities for the production of lightweight components, because of the high geometrical freedom that can be realized in comparison to conventional manufacturing processes. This potential gets demonstrated at the example of a bending beam. Therefore, a topology optimization is performed as well as the use of periodically arranged lattice structures. The latter ones show the constraint, that shear forces in the struts reduce the stiffness of the lattice. To avoid this, the structure has to be adapted to the flux of force. This thesis is supported by studies on a torqueloaded shaft.

  9. Adapting Cognitive Walkthrough to Support Game Based Learning Design

    ERIC Educational Resources Information Center

    Farrell, David; Moffat, David C.

    2014-01-01

    For any given Game Based Learning (GBL) project to be successful, the player must learn something. Designers may base their work on pedagogical research, but actual game design is still largely driven by intuition. People are famously poor at unsupported methodical thinking and relying so much on instinct is an obvious weak point in GBL design…

  10. Adapting the Mathematical Task Framework to Design Online Didactic Objects

    ERIC Educational Resources Information Center

    Bowers, Janet; Bezuk, Nadine; Aguilar, Karen

    2011-01-01

    Designing didactic objects involves imagining how students can conceive of specific mathematical topics and then imagining what types of classroom discussions could support these mental constructions. This study investigated whether it was possible to design Java applets that might serve as didactic objects to support online learning where…

  11. Using engineering control principles to inform the design of adaptive interventions: a conceptual introduction.

    PubMed

    Rivera, Daniel E; Pew, Michael D; Collins, Linda M

    2007-05-01

    The goal of this paper is to describe the role that control engineering principles can play in developing and improving the efficacy of adaptive, time-varying interventions. It is demonstrated that adaptive interventions constitute a form of feedback control system in the context of behavioral health. Consequently, drawing from ideas in control engineering has the potential to significantly inform the analysis, design, and implementation of adaptive interventions, leading to improved adherence, better management of limited resources, a reduction of negative effects, and overall more effective interventions. This article illustrates how to express an adaptive intervention in control engineering terms, and how to use this framework in a computer simulation to investigate the anticipated impact of intervention design choices on efficacy. The potential benefits of operationalizing decision rules based on control engineering principles are particularly significant for adaptive interventions that involve multiple components or address co-morbidities, situations that pose significant challenges to conventional clinical practice.

  12. Design of smart composite platforms for adaptive trust vector control and adaptive laser telescope for satellite applications

    NASA Astrophysics Data System (ADS)

    Ghasemi-Nejhad, Mehrdad N.

    2013-04-01

    This paper presents design of smart composite platforms for adaptive trust vector control (TVC) and adaptive laser telescope for satellite applications. To eliminate disturbances, the proposed adaptive TVC and telescope systems will be mounted on two analogous smart composite platform with simultaneous precision positioning (pointing) and vibration suppression (stabilizing), SPPVS, with micro-radian pointing resolution, and then mounted on a satellite in two different locations. The adaptive TVC system provides SPPVS with large tip-tilt to potentially eliminate the gimbals systems. The smart composite telescope will be mounted on a smart composite platform with SPPVS and then mounted on a satellite. The laser communication is intended for the Geosynchronous orbit. The high degree of directionality increases the security of the laser communication signal (as opposed to a diffused RF signal), but also requires sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum increases the data transmission rates, but laser systems require large amounts of power, which increases the mass and complexity of the supporting systems. In addition, the laser communication on the Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also addresses the design of an active composite platform to be used to simultaneously point and stabilize an intersatellite laser communication telescope with micro-radian pointing resolution. The telescope is a Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary). The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or else the optical properties of the system will be severely degraded. The alignment will also have to be maintained during thruster firings, which will require vibration suppression capabilities of the system as well. The innovative platform has been

  13. Designing Forest Adaptation Experiments through Manager-Scientist Partnerships

    NASA Astrophysics Data System (ADS)

    Nagel, L. M.; Swanston, C.; Janowiak, M.

    2014-12-01

    Three common forest adaptation options discussed in the context of an uncertain future climate are: creating resistance, promoting resilience, and enabling forests to respond to change. Though there is consensus on the broad management goals addressed by each of these options, translating these concepts into management plans specific for individual forest types that vary in structure, composition, and function remains a challenge. We will describe a decision-making framework that we employed within a manager-scientist partnership to develop a suite of adaptation treatments for two contrasting forest types as part of a long-term forest management experiment. The first, in northern Minnesota, is a red pine-dominated forest with components of white pine, aspen, paper birch, and northern red oak, with a hazel understory. The second, in southwest Colorado, is a warm-dry mixed conifer forest dominated by ponderosa pine, white fir, and Douglas-fir, with scattered aspen and an understory of Gambel oak. The current conditions at both sites are characterized by overstocking with moderate-to-high fuel loading, vulnerability to numerous forest health threats, and are generally uncharacteristic of historic structure and composition. The desired future condition articulated by managers for each site included elements of historic structure and natural range of variability, but were greatly tempered by known vulnerabilities and projected changes to climate and disturbance patterns. The resultant range of treatments we developed are distinct for each forest type, and address a wide range of management objectives.

  14. Adaptive optoelectronic camouflage systems with designs inspired by cephalopod skins.

    PubMed

    Yu, Cunjiang; Li, Yuhang; Zhang, Xun; Huang, Xian; Malyarchuk, Viktor; Wang, Shuodao; Shi, Yan; Gao, Li; Su, Yewang; Zhang, Yihui; Xu, Hangxun; Hanlon, Roger T; Huang, Yonggang; Rogers, John A

    2014-09-09

    Octopus, squid, cuttlefish, and other cephalopods exhibit exceptional capabilities for visually adapting to or differentiating from the coloration and texture of their surroundings, for the purpose of concealment, communication, predation, and reproduction. Long-standing interest in and emerging understanding of the underlying ultrastructure, physiological control, and photonic interactions has recently led to efforts in the construction of artificial systems that have key attributes found in the skins of these organisms. Despite several promising options in active materials for mimicking biological color tuning, existing routes to integrated systems do not include critical capabilities in distributed sensing and actuation. Research described here represents progress in this direction, demonstrated through the construction, experimental study, and computational modeling of materials, device elements, and integration schemes for cephalopod-inspired flexible sheets that can autonomously sense and adapt to the coloration of their surroundings. These systems combine high-performance, multiplexed arrays of actuators and photodetectors in laminated, multilayer configurations on flexible substrates, with overlaid arrangements of pixelated, color-changing elements. The concepts provide realistic routes to thin sheets that can be conformally wrapped onto solid objects to modulate their visual appearance, with potential relevance to consumer, industrial, and military applications.

  15. Adaptive optoelectronic camouflage systems with designs inspired by cephalopod skins

    PubMed Central

    Yu, Cunjiang; Li, Yuhang; Zhang, Xun; Huang, Xian; Malyarchuk, Viktor; Wang, Shuodao; Shi, Yan; Gao, Li; Su, Yewang; Zhang, Yihui; Xu, Hangxun; Hanlon, Roger T.; Huang, Yonggang; Rogers, John A.

    2014-01-01

    Octopus, squid, cuttlefish, and other cephalopods exhibit exceptional capabilities for visually adapting to or differentiating from the coloration and texture of their surroundings, for the purpose of concealment, communication, predation, and reproduction. Long-standing interest in and emerging understanding of the underlying ultrastructure, physiological control, and photonic interactions has recently led to efforts in the construction of artificial systems that have key attributes found in the skins of these organisms. Despite several promising options in active materials for mimicking biological color tuning, existing routes to integrated systems do not include critical capabilities in distributed sensing and actuation. Research described here represents progress in this direction, demonstrated through the construction, experimental study, and computational modeling of materials, device elements, and integration schemes for cephalopod-inspired flexible sheets that can autonomously sense and adapt to the coloration of their surroundings. These systems combine high-performance, multiplexed arrays of actuators and photodetectors in laminated, multilayer configurations on flexible substrates, with overlaid arrangements of pixelated, color-changing elements. The concepts provide realistic routes to thin sheets that can be conformally wrapped onto solid objects to modulate their visual appearance, with potential relevance to consumer, industrial, and military applications. PMID:25136094

  16. Twenty-five years of confirmatory adaptive designs: opportunities and pitfalls.

    PubMed

    Bauer, Peter; Bretz, Frank; Dragalin, Vladimir; König, Franz; Wassmer, Gernot

    2016-02-10

    'Multistage testing with adaptive designs' was the title of an article by Peter Bauer that appeared 1989 in the German journal Biometrie und Informatik in Medizin und Biologie. The journal does not exist anymore but the methodology found widespread interest in the scientific community over the past 25 years. The use of such multistage adaptive designs raised many controversial discussions from the beginning on, especially after the publication by Bauer and Köhne 1994 in Biometrics: Broad enthusiasm about potential applications of such designs faced critical positions regarding their statistical efficiency. Despite, or possibly because of, this controversy, the methodology and its areas of applications grew steadily over the years, with significant contributions from statisticians working in academia, industry and agencies around the world. In the meantime, such type of adaptive designs have become the subject of two major regulatory guidance documents in the US and Europe and the field is still evolving. Developments are particularly noteworthy in the most important applications of adaptive designs, including sample size reassessment, treatment selection procedures, and population enrichment designs. In this article, we summarize the developments over the past 25 years from different perspectives. We provide a historical overview of the early days, review the key methodological concepts and summarize regulatory and industry perspectives on such designs. Then, we illustrate the application of adaptive designs with three case studies, including unblinded sample size reassessment, adaptive treatment selection, and adaptive endpoint selection. We also discuss the availability of software for evaluating and performing such designs. We conclude with a critical review of how expectations from the beginning were fulfilled, and - if not - discuss potential reasons why this did not happen.

  17. Studying the neural bases of prism adaptation using fMRI: A technical and design challenge.

    PubMed

    Bultitude, Janet H; Farnè, Alessandro; Salemme, Romeo; Ibarrola, Danielle; Urquizar, Christian; O'Shea, Jacinta; Luauté, Jacques

    2016-12-30

    Prism adaptation induces rapid recalibration of visuomotor coordination. The neural mechanisms of prism adaptation have come under scrutiny since the observations that the technique can alleviate hemispatial neglect following stroke, and can alter spatial cognition in healthy controls. Relative to non-imaging behavioral studies, fMRI investigations of prism adaptation face several challenges arising from the confined physical environment of the scanner and the supine position of the participants. Any researcher who wishes to administer prism adaptation in an fMRI environment must adjust their procedures enough to enable the experiment to be performed, but not so much that the behavioral task departs too much from true prism adaptation. Furthermore, the specific temporal dynamics of behavioral components of prism adaptation present additional challenges for measuring their neural correlates. We developed a system for measuring the key features of prism adaptation behavior within an fMRI environment. To validate our configuration, we present behavioral (pointing) and head movement data from 11 right-hemisphere lesioned patients and 17 older controls who underwent sham and real prism adaptation in an MRI scanner. Most participants could adapt to prismatic displacement with minimal head movements, and the procedure was well tolerated. We propose recommendations for fMRI studies of prism adaptation based on the design-specific constraints and our results.

  18. Water Infrastructure Adaptation in New Urban Design: Possibilities and Constraints

    EPA Science Inventory

    Natural constraints, including climate change and dynamic socioeconomic development, can significantly impact the way we plan, design, and operate water infrastructure, thus its sustainability to deliver reliable quality water supplies and comply with environmental regulations. ...

  19. An adaptive two-stage sequential design for sampling rare and clustered populations

    USGS Publications Warehouse

    Brown, J.A.; Salehi, M.M.; Moradi, M.; Bell, G.; Smith, D.R.

    2008-01-01

    How to design an efficient large-area survey continues to be an interesting question for ecologists. In sampling large areas, as is common in environmental studies, adaptive sampling can be efficient because it ensures survey effort is targeted to subareas of high interest. In two-stage sampling, higher density primary sample units are usually of more interest than lower density primary units when populations are rare and clustered. Two-stage sequential sampling has been suggested as a method for allocating second stage sample effort among primary units. Here, we suggest a modification: adaptive two-stage sequential sampling. In this method, the adaptive part of the allocation process means the design is more flexible in how much extra effort can be directed to higher-abundance primary units. We discuss how best to design an adaptive two-stage sequential sample. ?? 2008 The Society of Population Ecology and Springer.

  20. Intelligent Adaptive Interface: A Design Tool for Enhancing Human-Machine System Performances

    DTIC Science & Technology

    2009-10-01

    environment) Monitoring • OMI Design Guidelines • Automation-design Principles • OMI Design Guidelines • HCI Principles Adapt OMI Automate / Aid...technical systems, there is still a lack of well-established design guidelines for these human-machine systems, especially for advanced operator...Additionally, a lack of integration between the Human Factors (HF) and Human Computer Interaction ( HCI ) domains has increased the tendency for terminology

  1. Regulatory perspectives on multiplicity in adaptive design clinical trials throughout a drug development program.

    PubMed

    Wang, Sue-Jane; Hung, H M James; O'Neill, Robert

    2011-07-01

    A clinical research program for drug development often consists of a sequence of clinical trials that may begin with uncontrolled and nonrandomized trials, followed by randomized trials or randomized controlled trials. Adaptive designs are not infrequently proposed for use. In the regulatory setting, the success of a drug development program can be defined to be that the experimental treatment at a specific dose level including regimen and frequency is approved based on replicated evidence from at least two confirmatory trials. In the early stage of clinical research, multiplicity issues are very broad. What is the maximum tolerable dose in an adaptive dose escalation trial? What should the dose range be to consider in an adaptive dose-ranging trial? What is the minimum effective dose in an adaptive dose-response study given the tolerability and the toxicity observable in short term or premarketing trials? Is establishing the dose-response relationship important or the ability to select a superior treatment with high probability more important? In the later stage of clinical research, multiplicity problems can be formulated with better focus, depending on whether the study is for exploration to estimate or select design elements or for labeling consideration. What is the study objective for an early-phase versus a later phase adaptive clinical trial? How many doses are to be studied in the early exploratory adaptive trial versus in the confirmatory adaptive trial? Is the intended patient population well defined or is the applicable patient population yet to be adaptively selected in the trial due to the potential patient and/or disease heterogeneity? Is the primary efficacy endpoint well defined or still under discussion providing room for adaptation? What are the potential treatment indications that may adaptively lead to an intended-to-treat patient population and the primary efficacy endpoint? In this work we stipulate the multiplicity issues with adaptive

  2. Adaptive urn designs for estimating several percentiles of a dose--response curve.

    PubMed

    Mugno, Raymond; Zhus, Wei; Rosenberger, William F

    2004-07-15

    Dose--response experiments are crucial in biomedical studies. There are usually multiple objectives in such experiments and among the goals is the estimation of several percentiles on the dose--response curve. Here we present the first non-parametric adaptive design approach to estimate several percentiles simultaneously via generalized Pólya urns. Theoretical properties of these designs are investigated and their performance is gaged by the locally compound optimal designs. As an example, we re-investigated a psychophysical experiment where one of the goals was to estimate the three quartiles. We show that these multiple-objective adaptive designs are more efficient than the original single-objective adaptive design targeting the median only. We also show that urn designs which target the optimal designs are slightly more efficient than those which target the desired percentiles directly. Guidelines are given as to when to use which type of design. Overall we are pleased with the efficiency results and hope compound adaptive designs proposed in this work or their variants may prove to be a viable non-parametric alternative in multiple-objective dose--response studies.

  3. Optimal adaptive two-stage designs for early phase II clinical trials.

    PubMed

    Shan, Guogen; Wilding, Gregory E; Hutson, Alan D; Gerstenberger, Shawn

    2016-04-15

    Simon's optimal two-stage design has been widely used in early phase clinical trials for Oncology and AIDS studies with binary endpoints. With this approach, the second-stage sample size is fixed when the trial passes the first stage with sufficient activity. Adaptive designs, such as those due to Banerjee and Tsiatis (2006) and Englert and Kieser (2013), are flexible in the sense that the second-stage sample size depends on the response from the first stage, and these designs are often seen to reduce the expected sample size under the null hypothesis as compared with Simon's approach. An unappealing trait of the existing designs is that they are not associated with a second-stage sample size, which is a non-increasing function of the first-stage response rate. In this paper, an efficient intelligent process, the branch-and-bound algorithm, is used in extensively searching for the optimal adaptive design with the smallest expected sample size under the null, while the type I and II error rates are maintained and the aforementioned monotonicity characteristic is respected. The proposed optimal design is observed to have smaller expected sample sizes compared to Simon's optimal design, and the maximum total sample size of the proposed adaptive design is very close to that from Simon's method. The proposed optimal adaptive two-stage design is recommended for use in practice to improve the flexibility and efficiency of early phase therapeutic development.

  4. A modified varying-stage adaptive phase II/III clinical trial design.

    PubMed

    Dong, Gaohong; Vandemeulebroecke, Marc

    2016-07-01

    Conventionally, adaptive phase II/III clinical trials are carried out with a strict two-stage design. Recently, a varying-stage adaptive phase II/III clinical trial design has been developed. In this design, following the first stage, an intermediate stage can be adaptively added to obtain more data, so that a more informative decision can be made. Therefore, the number of further investigational stages is determined based upon data accumulated to the interim analysis. This design considers two plausible study endpoints, with one of them initially designated as the primary endpoint. Based on interim results, another endpoint can be switched as the primary endpoint. However, in many therapeutic areas, the primary study endpoint is well established. Therefore, we modify this design to consider one study endpoint only so that it may be more readily applicable in real clinical trial designs. Our simulations show that, the same as the original design, this modified design controls the Type I error rate, and the design parameters such as the threshold probability for the two-stage setting and the alpha allocation ratio in the two-stage setting versus the three-stage setting have a great impact on the design characteristics. However, this modified design requires a larger sample size for the initial stage, and the probability of futility becomes much higher when the threshold probability for the two-stage setting gets smaller. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Adaptive Pareto Set Estimation for Stochastic Mixed Variable Design Problems

    DTIC Science & Technology

    2009-03-01

    Improved Feature Extraction, Feature Selection, and Identification Techniques that Create a Fast Unsupervised Hyperspectral Target Detection Algorithm...optional): ______________________________________ General Category / Classification : [ ] core values [ ] command [ ] strategy...Optimization, 8(3), 631-657. 125 23. Davis, M. (2009). Using Multiple Robust Parameter Design Techniques to Improve Hyperspectral Anomaly

  6. Context-Aware Design for Process Flexibility and Adaptation

    ERIC Educational Resources Information Center

    Yao, Wen

    2012-01-01

    Today's organizations face continuous and unprecedented changes in their business environment. Traditional process design tools tend to be inflexible and can only support rigidly defined processes (e.g., order processing in the supply chain). This considerably restricts their real-world applications value, especially in the dynamic and…

  7. Adapting Wood Technology to Teach Design and Engineering

    ERIC Educational Resources Information Center

    Rummel, Robert A.

    2012-01-01

    Technology education has changed dramatically over the last few years. The transition of industrial arts to technology education and more recently the pursuit of design and engineering has resulted in technology education teachers often needing to change their curriculum and course activities to meet the demands of a rapidly changing profession.…

  8. A Testlet Assembly Design for Adaptive Multistage Tests

    ERIC Educational Resources Information Center

    Luecht, Richard; Brumfield, Terry; Breithaupt, Krista

    2006-01-01

    This article describes multistage tests and some practical test development considerations related to the design and implementation of a multistage test, using the Uniform CPA (certified public accountant) Examination as a case study. The article further discusses the use of automated test assembly procedures in an operational context to produce…

  9. Design and analysis of closed-loop decoder adaptation algorithms for brain-machine interfaces.

    PubMed

    Dangi, Siddharth; Orsborn, Amy L; Moorman, Helene G; Carmena, Jose M

    2013-07-01

    Closed-loop decoder adaptation (CLDA) is an emerging paradigm for achieving rapid performance improvements in online brain-machine interface (BMI) operation. Designing an effective CLDA algorithm requires making multiple important decisions, including choosing the timescale of adaptation, selecting which decoder parameters to adapt, crafting the corresponding update rules, and designing CLDA parameters. These design choices, combined with the specific settings of CLDA parameters, will directly affect the algorithm's ability to make decoder parameters converge to values that optimize performance. In this article, we present a general framework for the design and analysis of CLDA algorithms and support our results with experimental data of two monkeys performing a BMI task. First, we analyze and compare existing CLDA algorithms to highlight the importance of four critical design elements: the adaptation timescale, selective parameter adaptation, smooth decoder updates, and intuitive CLDA parameters. Second, we introduce mathematical convergence analysis using measures such as mean-squared error and KL divergence as a useful paradigm for evaluating the convergence properties of a prototype CLDA algorithm before experimental testing. By applying these measures to an existing CLDA algorithm, we demonstrate that our convergence analysis is an effective analytical tool that can ultimately inform and improve the design of CLDA algorithms.

  10. Technical Data Exchange Software Tools Adapted to Distributed Microsatellite Design

    NASA Astrophysics Data System (ADS)

    Pache, Charly

    2002-01-01

    One critical issue concerning distributed design of satellites, is the collaborative work it requires. In particular, the exchange of data between each group responsible for each subsystem can be complex and very time-consuming. The goal of this paper is to present a design collaborative tool, the SSETI Design Model (SDM), specifically developed for enabling satellite distributed design. SDM is actually used in the ongoing Student Space Exploration &Technology (SSETI) initiative (www.sseti.net). SSETI is lead by European Space Agency (ESA) outreach office (http://www.estec.esa.nl/outreach), involving student groups from all over Europe for design, construction and launch of a microsatellite. The first part of this paper presents the current version of the SDM tool, a collection of Microsoft Excel linked worksheets, one for each subsystem. An overview of the project framework/structure is given, explaining the different actors, the flows between them, as well as the different types of data and the links - formulas - between data sets. Unified Modeling Language (UML) diagrams give an overview of the different parts . Then the SDM's functionalities, developed in VBA scripts (Visual Basic for Application), are introduced, as well as the interactive features, user interfaces and administration tools. The second part discusses the capabilities and limitations of SDM current version. Taking into account these capabilities and limitations, the third part outlines the next version of SDM, a web-oriented, database-driven evolution of the current version. This new approach will enable real-time data exchange and processing between the different actors of the mission. Comprehensive UML diagrams will guide the audience through the entire modeling process of such a system. Tradeoffs simulation capabilities, security, reliability, hardware and software issues will also be thoroughly discussed.

  11. Group-Work in the Design of Complex Adaptive Learning Strategies

    ERIC Educational Resources Information Center

    Mavroudi, Anna; Hadzilacos, Thanasis

    2013-01-01

    This paper presents a case study where twelve graduate students undertook the demanding role of the adaptive e-course developer and worked collaboratively on an authentic and complex design task in the context of open and distance tertiary education. The students had to work in groups in order to conceptualise and design a learning scenario for…

  12. Incorporation of Content Balancing Requirements in Stratification Designs for Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Leung, Chi-Keung; Chang, Hua-Hua; Hau, Kit-Tai

    2003-01-01

    Studied three stratification designs for computerized adaptive testing in conjunction with three well-developed content balancing methods. Simulation study results show substantial differences in item overlap rate and pool utilization among different methods. Recommends an optimal combination of stratification design and content balancing method.…

  13. A Framework for Adaptive Learning Design in a Web-Conferencing Environment

    ERIC Educational Resources Information Center

    Bower, Matt

    2016-01-01

    Many recent technologies provide the ability to dynamically adjust the interface depending on the emerging cognitive and collaborative needs of the learning episode. This means that educators can adaptively re-design the learning environment during the lesson, rather than purely relying on preemptive learning design thinking. Based on a…

  14. An adaptive Simon Two-Stage Design for Phase 2 studies of targeted therapies.

    PubMed

    Jones, Cheryl L; Holmgren, Eric

    2007-09-01

    The field of specialized medicine and clinical development programs for targeted cancer therapies are rapidly expanding. The proposed Phase 2 design allows for preliminary determination of efficacy that may be restricted to a particular sub-population defined by biomarker status (presence/absence). The design is an adaptation of the Simon Two-Stage Design. We provide examples where the adaptation can result in substantial savings in sample size and thus potentially lead to greater efficiency in decision making during the drug development process.

  15. A new approach for designing self-organizing systems and application to adaptive control

    NASA Technical Reports Server (NTRS)

    Ramamoorthy, P. A.; Zhang, Shi; Lin, Yueqing; Huang, Song

    1993-01-01

    There is tremendous interest in the design of intelligent machines capable of autonomous learning and skillful performance under complex environments. A major task in designing such systems is to make the system plastic and adaptive when presented with new and useful information and stable in response to irrelevant events. A great body of knowledge, based on neuro-physiological concepts, has evolved as a possible solution to this problem. Adaptive resonance theory (ART) is a classical example under this category. The system dynamics of an ART network is described by a set of differential equations with nonlinear functions. An approach for designing self-organizing networks characterized by nonlinear differential equations is proposed.

  16. Simple adaptive control system design for a quadrotor with an internal PFC

    SciTech Connect

    Mizumoto, Ikuro; Nakamura, Takuto; Kumon, Makoto; Takagi, Taro

    2014-12-10

    The paper deals with an adaptive control system design problem for a four rotor helicopter or quadrotor. A simple adaptive control design scheme with a parallel feedforward compensator (PFC) in the internal loop of the considered quadrotor will be proposed based on the backstepping strategy. As is well known, the backstepping control strategy is one of the advanced control strategy for nonlinear systems. However, the control algorithm will become complex if the system has higher order relative degrees. We will show that one can skip some design steps of the backstepping method by introducing a PFC in the inner loop of the considered quadrotor, so that the structure of the obtained controller will be simplified and a high gain based adaptive feedback control system will be designed. The effectiveness of the proposed method will be confirmed through numerical simulations.

  17. Adaptive Clinical Trial Designs for Simultaneous Testing of Matched Diagnostics and Therapeutics

    PubMed Central

    Scher, Howard I.; Nasso, Shelley Fuld; Rubin, Eric H.; Simon, Richard

    2013-01-01

    A critical challenge in the development of new molecularly targeted anticancer drugs is the identification of predictive biomarkers and the concurrent development of diagnostics for these biomarkers. Developing matched diagnostics and therapeutics will require new clinical trial designs and methods of data analysis. The use of adaptive design in phase III trials may offer new opportunities for matched diagnosis and treatment because the size of the trial can allow for subpopulation analysis. We present an adaptive phase III trial design that can identify a suitable target population during the early course of the trial, enabling the efficacy of an experimental therapeutic to be evaluated within the target population as a later part of the same trial. The use of such an adaptive approach to clinical trial design has the potential to greatly improve the field of oncology and facilitate the development of personalized medicine. PMID:22046024

  18. On Adaptive Extended Compatibility Changing Type of Product Design Strategy

    NASA Astrophysics Data System (ADS)

    Wenwen, Jiang; Zhibin, Xie

    The article uses research ways of Enterprise localization and enterprise's development course to research strategy of company's product design and development. It announces at different stages for development, different kinds of enterprises will adopt product design and development policies of different modes. It also announces close causality between development course of company and central technology and product. The result indicated enterprises in leading position in market, technology and brand adopt pioneer strategy type of product research and development. These enterprise relying on the large-scale leading enterprise offering a complete set service adopts the passively duplicating type tactic of product research and development. Some enterprise in part of advantage in technology, market, management or brand adopt following up strategy of product research and development. The enterprises with relative advantage position adopt the strategy of technology applied taking optimizing services as centre in product research and development in fields of brand culture and market service.

  19. Theory and Design of Adaptive Automation in Aviation Systems

    DTIC Science & Technology

    1992-07-17

    and KOALAS programs at the Naval Air Development Center. The latter is an intelligent, man-in-the-loop, architecture that is presently being...7 This approach has been applied as a model in the Knowledgeable Operator Analysis- Unked System ( KOALAS ) for decision aiding and has in turn been...Barrett,C.L. (1988) The Knowledgeable Ooerator Analysis-Linked Advisory System ( KOALAS ) A1oroach to Decision Suooort System Design. Analysis and Synthesis

  20. Offset prediction for charge-balanced stimulus waveforms.

    PubMed

    Woods, V M; Triantis, I F; Toumazou, C

    2011-08-01

    Functional electrical stimulation with cuff electrodes involves the controlled injection of current into an electrically excitable tissue for sensory or motor rehabilitation. Some charge injected during stimulation is 'lost' at the electrode-electrolyte interface when the charge carrier is translated from an electron to an ion in the solution. The process of charge injection through chemical reactions can reduce electrode longevity and implant biocompatibility. Conventionally, the excess charge is minimized by complex hardware solutions, which are often not appropriate for robust long-term implantable solutions. Here, we present a method of waveform design that minimizes irrecoverable charge during continuous pulsing through the use of biphasic waveforms with unequally charged phases. We developed an equivalent electrical model of the electrode-electrolyte impedance based on the electrode's surface chemistry during psuedo-bipolar stimulation conditions. Simulations with the equivalent circuit determined the uncompensated charge to be a function of stimulus parameters. In vitro stimulation experiments in saline confirmed that we could preemptively compensate for the excess charge following biphasic stimulus waveforms. As a result, there was a 92% reduction in the pre-pulse potential after a pulse train with this new waveform design when compared to stimulation with conventional biphasic waveforms.

  1. Waveform-Sampling Electronics for a Whole-Body Time-of-Flight PET Scanner

    PubMed Central

    Ashmanskas, W. J.; LeGeyt, B. C.; Newcomer, F. M.; Panetta, J. V.; Ryan, W. A.; Van Berg, R.; Wiener, R. I.; Karp Fellow, J. S.

    2014-01-01

    Waveform sampling is an appealing technique for instruments requiring precision time and pulse-height measurements. Sampling each PMT waveform at oscilloscope-like rates of several gigasamples per second enables one to process PMT signals digitally, which in turn makes it straightforward to optimize timing resolution and amplitude (energy and position) resolution in response to calibration effects, pile-up effects, and other systematic sources of waveform variation. We describe a system design and preliminary implementation that neatly maps waveform-sampling technology onto the LaPET prototype whole-body time-of-flight PET scanner that serves as the platform for testing this new technology. PMID:25484379

  2. The Study and Design of Adaptive Learning System Based on Fuzzy Set Theory

    NASA Astrophysics Data System (ADS)

    Jia, Bing; Zhong, Shaochun; Zheng, Tianyang; Liu, Zhiyong

    Adaptive learning is an effective way to improve the learning outcomes, that is, the selection of learning content and presentation should be adapted to each learner's learning context, learning levels and learning ability. Adaptive Learning System (ALS) can provide effective support for adaptive learning. This paper proposes a new ALS based on fuzzy set theory. It can effectively estimate the learner's knowledge level by test according to learner's target. Then take the factors of learner's cognitive ability and preference into consideration to achieve self-organization and push plan of knowledge. This paper focuses on the design and implementation of domain model and user model in ALS. Experiments confirmed that the system providing adaptive content can effectively help learners to memory the content and improve their comprehension.

  3. Design and Preliminary Testing of the International Docking Adapter's Peripheral Docking Target

    NASA Technical Reports Server (NTRS)

    Foster, Christopher W.; Blaschak, Johnathan; Eldridge, Erin A.; Brazzel, Jack P.; Spehar, Peter T.

    2015-01-01

    The International Docking Adapter's Peripheral Docking Target (PDT) was designed to allow a docking spacecraft to judge its alignment relative to the docking system. The PDT was designed to be compatible with relative sensors using visible cameras, thermal imagers, or Light Detection and Ranging (LIDAR) technologies. The conceptual design team tested prototype designs and materials to determine the contrast requirements for the features. This paper will discuss the design of the PDT, the methodology and results of the tests, and the conclusions pertaining to PDT design that were drawn from testing.

  4. An MSK Waveform for Radar Applications

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2009-01-01

    We introduce a minimum shift keying (MSK) waveform developed for use in radar applications. This waveform is characterized in terms of its spectrum, autocorrelation, and ambiguity function, and is compared with the conventionally used bi-phase coded (BPC) radar signal. It is shown that the MSK waveform has several advantages when compared with the BPC waveform, and is a better candidate for deep-space radar imaging systems such as NASA's Goldstone Solar System Radar.

  5. Adaptive fuzzy switched control design for uncertain nonholonomic systems with input nonsmooth constraint

    NASA Astrophysics Data System (ADS)

    Li, Yongming; Tong, Shaocheng

    2016-10-01

    In this paper, a fuzzy adaptive switched control approach is proposed for a class of uncertain nonholonomic chained systems with input nonsmooth constraint. In the control design, an auxiliary dynamic system is designed to address the input nonsmooth constraint, and an adaptive switched control strategy is constructed to overcome the uncontrollability problem associated with x0(t0) = 0. By using fuzzy logic systems to tackle unknown nonlinear functions, a fuzzy adaptive control approach is explored based on the adaptive backstepping technique. By constructing the combination approximation technique and using Young's inequality scaling technique, the number of the online learning parameters is reduced to n and the 'explosion of complexity' problem is avoid. It is proved that the proposed method can guarantee that all variables of the closed-loop system converge to a small neighbourhood of zero. Two simulation examples are provided to illustrate the effectiveness of the proposed control approach.

  6. Adaptive critic autopilot design of bank-to-turn missiles using fuzzy basis function networks.

    PubMed

    Lin, Chuan-Kai

    2005-04-01

    A new adaptive critic autopilot design for bank-to-turn missiles is presented. In this paper, the architecture of adaptive critic learning scheme contains a fuzzy-basis-function-network based associative search element (ASE), which is employed to approximate nonlinear and complex functions of bank-to-turn missiles, and an adaptive critic element (ACE) generating the reinforcement signal to tune the associative search element. In the design of the adaptive critic autopilot, the control law receives signals from a fixed gain controller, an ASE and an adaptive robust element, which can eliminate approximation errors and disturbances. Traditional adaptive critic reinforcement learning is the problem faced by an agent that must learn behavior through trial-and-error interactions with a dynamic environment, however, the proposed tuning algorithm can significantly shorten the learning time by online tuning all parameters of fuzzy basis functions and weights of ASE and ACE. Moreover, the weight updating law derived from the Lyapunov stability theory is capable of guaranteeing both tracking performance and stability. Computer simulation results confirm the effectiveness of the proposed adaptive critic autopilot.

  7. Frequency-based design of Adaptive Optics systems

    NASA Astrophysics Data System (ADS)

    Agapito, Guido; Battistelli, Giorgio; Mari, Daniele; Selvi, Daniela; Tesi, Alberto; Tesi, Pietro

    2013-12-01

    The problem of reducing the effects of wavefront distortion and structural vibrations inground-based telescopes is addressed within a modal-control framework. The proposed approach aimsat optimizing the parameters of a given modal stabilizing controller with respect to a performance criterionwhich reflects the residual phase variance and is defined on a sampled frequency domain. Thisframework makes it possible to account for turbulence and vibration profiles of arbitrary complexity(even empirical power spectral densities from data), while the controller order can be kept at a desiredvalue. Moreover it is possible to take into account additional requirements, as robustness in the presenceof disturbances whose intensity and frequency profile vary with time. The proposed design procedureresults in solving a minmax problem and can be converted into a linear programming problem withquadratic constraints, for which there exist several standard optimization techniques. The optimizationstarts from a given stabilizing controller which can be either a non-model-based controller (in this caseno identification effort is required), or a model-based controller synthesized by means of turbulence andvibration models of limited complexity. In this sense the approach can be viewed not only as alternative,but also as cooperative with other control design approaches. The results obtained by means of anEnd-to-End simulator are shown to emphasize the power of the proposed method.

  8. Low Level Waste Conceptual Design Adaption to Poor Geological Conditions

    SciTech Connect

    Bell, J.; Drimmer, D.; Giovannini, A.; Manfroy, P.; Maquet, F.; Schittekat, J.; Van Cotthem, A.; Van Echelpoel, E.

    2002-02-26

    Since the early eighties, several studies have been carried out in Belgium with respect to a repository for the final disposal of low-level radioactive waste (LLW). In 1998, the Belgian Government decided to restrict future investigations to the four existing nuclear sites in Belgium or sites that might show interest. So far, only two existing nuclear sites have been thoroughly investigated from a geological and hydrogeological point of view. These sites are located in the North-East (Mol-Dessel) and in the mid part (Fleurus-Farciennes) of the country. Both sites have the disadvantage of presenting poor geological and hydrogeological conditions, which are rather unfavorable to accommodate a surface disposal facility for LLW. The underground of the Mol-Dessel site consists of neogene sand layers of about 180 m thick which cover a 100 meters thick clay layer. These neogene sands contain, at 20 m depth, a thin clayey layer. The groundwater level is quite close to the surface (0-2m) and finally, the topography is almost totally flat. The upper layer of the Fleurus-Farciennes site consists of 10 m silt with poor geomechanical characteristics, overlying sands (only a few meters thick) and Westphalian shales between 15 and 20 m depth. The Westphalian shales are tectonized and strongly weathered. In the past, coal seams were mined out. This activity induced locally important surface subsidence. For both nuclear sites that were investigated, a conceptual design was made that could allow any unfavorable geological or hydrogeological conditions of the site to be overcome. In Fleurus-Farciennes, for instance, the proposed conceptual design of the repository is quite original. It is composed of a shallow, buried concrete cylinder, surrounded by an accessible concrete ring, which allows permanent inspection and control during the whole lifetime of the repository. Stability and drainage systems should be independent of potential differential settlements an d subsidences

  9. Versatile Dual-Channel Waveform Generator

    NASA Technical Reports Server (NTRS)

    Staples, Edward J.; Lie, Sen; Ching, Michael; Budinger, James M.

    1994-01-01

    Programmable waveform generator synthesizes two independent waveforms simultaneously at frequencies up to 250 MHz. Can be in phase or out of phase with each other. Use of commercial integrated circuits helps keep cost low. Operation governed by BASIC source code enabling any user equipped with suitable personal computer to specify waveforms. User can modify source code to satisfy special needs. Other applications include simulation of Doppler waveforms for radar, and of video signals for testing color displays and computer monitors. With eventual substitution of gallium arsenide integrated circuits for its present silicon integrated circuits, instrument able to generate waveforms with 14-bit precision and sample rates as high as 2 GHz.

  10. Selection and generation of waveforms for differential mobility spectrometry

    SciTech Connect

    Krylov, Evgeny V.; Coy, Stephen L.; Nazarov, Erkinjon G.; Vandermey, John; Schneider, Bradley B.; Covey, Thomas R.

    2010-02-15

    Devices based on differential mobility spectrometry (DMS) are used in a number of ways, including applications as ion prefilters for API-MS systems, as detectors or selectors in hybrid instruments (GC-DMS, DMS-IMS), and in standalone systems for chemical detection and identification. DMS ion separation is based on the relative difference between high field and low field ion mobility known as the alpha dependence, and requires the application of an intense asymmetric electric field known as the DMS separation field, typically in the megahertz frequency range. DMS performance depends on the waveform and on the magnitude of this separation field. In this paper, we analyze the relationship between separation waveform and DMS resolution and consider feasible separation field generators. We examine ideal and practical DMS separation field waveforms and discuss separation field generator circuit types and their implementations. To facilitate optimization of the generator designs, we present a set of relations that connect ion alpha dependence to DMS separation fields. Using these relationships we evaluate the DMS separation power of common generator types as a function of their waveform parameters. Optimal waveforms for the major types of DMS separation generators are determined for ions with various alpha dependences. These calculations are validated by comparison with experimental data.

  11. Evaluation of novel stimulus waveforms for deep brain stimulation

    PubMed Central

    Foutz, TJ; McIntyre, CC

    2010-01-01

    Deep brain stimulation (DBS) is an established therapy for the treatment of a wide range of neurological disorders. Historically, DBS and other neurostimulation technologies have relied on rectangular stimulation waveforms to impose their effects on the nervous system. Recent work has suggested that non-rectangular waveforms may have advantages over the traditional rectangular pulse. Therefore, we used detailed computer models to compare a range of charge-balanced biphasic waveforms with rectangular, exponential, triangular, Gaussian, and sinusoidal stimulus pulse shapes. We explored the neural activation energy of these waveforms in both intracellular and extracellular stimulation. In the context of extracellular stimulation, we compared their effects on both axonal fibers of passage and projection neurons. Finally, we evaluated the impact of delivering the waveforms through a clinical DBS electrode, as opposed to a theoretical point source. Our results suggest that DBS with a 1 ms centered-triangular pulse can decrease energy consumption by 64 % when compared to the standard 100 μs rectangular pulse (energy cost of 48 nJ and 133 nJ, respectively, to stimulate 50 % of a distributed population of axons) and can decrease energy consumption by 10 % when compared to the most energy efficient rectangular pulse (1.25 ms duration). In turn, there may be measureable energy savings when using appropriately designed non-rectangular pulses in clinical DBS applications, thereby warranting further experimental investigation. PMID:21084732

  12. Evaluation of novel stimulus waveforms for deep brain stimulation

    NASA Astrophysics Data System (ADS)

    Foutz, Thomas J.; McIntyre, Cameron C.

    2010-12-01

    Deep brain stimulation (DBS) is an established therapy for the treatment of a wide range of neurological disorders. Historically, DBS and other neurostimulation technologies have relied on rectangular stimulation waveforms to impose their effects on the nervous system. Recent work has suggested that non-rectangular waveforms may have advantages over the traditional rectangular pulse. Therefore, we used detailed computer models to compare a range of charge-balanced biphasic waveforms with rectangular, exponential, triangular, Gaussian and sinusoidal stimulus pulse shapes. We explored the neural activation energy of these waveforms for both intracellular and extracellular current-controlled stimulation conditions. In the context of extracellular stimulation, we compared their effects on both axonal fibers of passage and projection neurons. Finally, we evaluated the impact of delivering the waveforms through a clinical DBS electrode, as opposed to a theoretical point source. Our results suggest that DBS with a 1 ms centered-triangular pulse can decrease energy consumption by 64% when compared with the standard 100 µs rectangular pulse (energy cost of 48 and 133 nJ, respectively, to stimulate 50% of a distributed population of axons) and can decrease energy consumption by 10% when compared with the most energy efficient rectangular pulse (1.25 ms duration). In turn, there may be measureable energy savings when using appropriately designed non-rectangular pulses in clinical DBS applications, thereby warranting further experimental investigation.

  13. First-order design of off-axis reflective ophthalmic adaptive optics systems using afocal telescopes.

    PubMed

    Gómez-Vieyra, Armando; Dubra, Alfredo; Malacara-Hernández, Daniel; Williams, David R

    2009-10-12

    Expressions for minimal astigmatism in image and pupil planes in off-axis afocal reflective telescopes formed by pairs of spherical mirrors are presented. These formulae which are derived from the marginal ray fan equation can be used for designing laser cavities, spectrographs and adaptive optics retinal imaging systems. The use, range and validity of these formulae are limited by spherical aberration and coma for small and large angles respectively. This is discussed using examples from adaptive optics retinal imaging systems. The performance of the resulting optical designs are evaluated and compared against the configurations with minimal wavefront RMS, using the defocus-corrected wavefront RMS as a metric.

  14. Arbitrary waveform generation using optical direct digital synthesis

    NASA Astrophysics Data System (ADS)

    Chester-Parsons, J.

    2013-11-01

    The objective of this paper is to describe the progress of a project designed to build on recent photonic capabilities in order to develop an ultra-wide band, true Arbitrary Waveform Generator (AWG) capable of providing radar quality signals in the 500MHz to 20GHz spectrum using photonic integration. Within this scope, it is planned to create a single channel radar environment simulator based on a photonic waveform generator, which will demonstrate the dynamic range, stability, and high signal fidelity required to simulate the modern complex radar environment. The paper will present recent measurements of critical parameters that are vital for the practical realisation of this system on a chip.

  15. Why Waveform Correlation Sometimes Fails

    NASA Astrophysics Data System (ADS)

    Carmichael, J.

    2015-12-01

    Waveform correlation detectors used in explosion monitoring scan noisy geophysical data to test two competing hypotheses: either (1) an amplitude-scaled version of a template waveform is present, or, (2) no signal is present at all. In reality, geophysical wavefields that are monitored for explosion signatures include waveforms produced by non-target sources that are partially correlated with the waveform template. Such signals can falsely trigger correlation detectors, particularly at low thresholds required to monitor for smaller target explosions. This challenge is particularly formidable when monitoring known test sites for seismic disturbances, since uncatalogued natural seismicity is (generally) more prevalent at lower magnitudes, and could be mistaken for small explosions. To address these challenges, we identify real examples in which correlation detectors targeting explosions falsely trigger on both site-proximal earthquakes (Figure 1, below) and microseismic "noise". Motivated by these examples, we quantify performance loss when applying these detectors, and re-evaluate the correlation-detector's hypothesis test. We thereby derive new detectors from more general hypotheses that admit unknown background seismicity, and apply these to real data. From our treatment, we derive "rules of thumb'' for proper template and threshold selection in heavily cluttered signal environments. Last, we answer the question "what is the probability of falsely detecting an earthquake collocated at a test site?", using correlation detectors that include explosion-triggered templates. Figure Top: An eight-channel data stream (black) recorded from an earthquake near a mine. Red markers indicate a detection. Middle: The correlation statistic computed by scanning the template against the data stream at top. The red line indicates the threshold for event declaration, determined by a false-alarm on noise probability constraint, as computed from the signal-absent distribution using

  16. Analysing the ventricular fibrillation waveform.

    PubMed

    Reed, Matthew J; Clegg, Gareth R; Robertson, Colin E

    2003-04-01

    The surface electrocardiogram associated with ventricular fibrillation has been of interest to researchers for some time. Over the last few decades, techniques have been developed to analyse this signal in an attempt to obtain more information about the state of the myocardium and the chances of successful defibrillation. This review looks at the implications of analysing the VF waveform and discusses the various techniques that have been used, including fast Fourier transform analysis, wavelet transform analysis and mathematical techniques such as chaos theory.

  17. Photonic Arbitrary Waveform Generation Technology

    DTIC Science & Technology

    2006-06-01

    filters or ring resonator based technologies [26-29]. Key aspects of the filter technology are the flatness of the filter channel, the crosstalk...photodetectors would also be warranted. 28 References [1] K. Nosu, “ Advanced coherent lightwave technologies ,” IEEE Commun. Magn,, vol. 26...AFRL-SN-RS-TR-2006-208 Final Technical Report June 2006 PHOTONIC ARBITRARY WAVEFORM GENERATION TECHNOLOGY University of

  18. Automated Analysis, Classification, and Display of Waveforms

    NASA Technical Reports Server (NTRS)

    Kwan, Chiman; Xu, Roger; Mayhew, David; Zhang, Frank; Zide, Alan; Bonggren, Jeff

    2004-01-01

    A computer program partly automates the analysis, classification, and display of waveforms represented by digital samples. In the original application for which the program was developed, the raw waveform data to be analyzed by the program are acquired from space-shuttle auxiliary power units (APUs) at a sampling rate of 100 Hz. The program could also be modified for application to other waveforms -- for example, electrocardiograms. The program begins by performing principal-component analysis (PCA) of 50 normal-mode APU waveforms. Each waveform is segmented. A covariance matrix is formed by use of the segmented waveforms. Three eigenvectors corresponding to three principal components are calculated. To generate features, each waveform is then projected onto the eigenvectors. These features are displayed on a three-dimensional diagram, facilitating the visualization of the trend of APU operations.

  19. Design of an LVDS to USB3.0 adapter and application

    NASA Astrophysics Data System (ADS)

    Qiu, Xiaohan; Wang, Yu; Zhao, Xin; Chang, Zhen; Zhang, Quan; Tian, Yuze; Zhang, Yunyi; Lin, Fang; Liu, Wenqing

    2016-10-01

    USB 3.0 specification was published in 2008. With the development of technology, USB 3.0 is becoming popular. LVDS(Low Voltage Differential Signaling) to USB 3.0 Adapter connects the communication port of spectrometer device and the USB 3.0 port of a computer, and converts the output of an LVDS spectrometer device data to USB. In order to adapt to the changing and developing of technology, LVDS to USB3.0 Adapter was designed and developed based on LVDS to USB2.0 Adapter. The CYUSB3014, a new generation of USB bus interface chip produced by Cypress and conforming to USB3.0 communication protocol, utilizes GPIF-II (GPIF, general programmable interface) to connect the FPGA and increases effective communication speed to 2Gbps. Therefore, the adapter, based on USB3.0 technology, is able to connect more spectrometers to single computer and provides technical basis for the development of the higher speed industrial camera. This article describes the design and development process of the LVDS to USB3.0 adapter.

  20. Design of a Model Reference Adaptive Controller for an Unmanned Air Vehicle

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Matsutani, Megumi; Annaswamy, Anuradha M.

    2010-01-01

    This paper presents the "Adaptive Control Technology for Safe Flight (ACTS)" architecture, which consists of a non-adaptive controller that provides satisfactory performance under nominal flying conditions, and an adaptive controller that provides robustness under off nominal ones. The design and implementation procedures of both controllers are presented. The aim of these procedures, which encompass both theoretical and practical considerations, is to develop a controller suitable for flight. The ACTS architecture is applied to the Generic Transport Model developed by NASA-Langley Research Center. The GTM is a dynamically scaled test model of a transport aircraft for which a flight-test article and a high-fidelity simulation are available. The nominal controller at the core of the ACTS architecture has a multivariable LQR-PI structure while the adaptive one has a direct, model reference structure. The main control surfaces as well as the throttles are used as control inputs. The inclusion of the latter alleviates the pilot s workload by eliminating the need for cancelling the pitch coupling generated by changes in thrust. Furthermore, the independent usage of the throttles by the adaptive controller enables their use for attitude control. Advantages and potential drawbacks of adaptation are demonstrated by performing high fidelity simulations of a flight-validated controller and of its adaptive augmentation.

  1. Waveform Freezing of Sonic Booms Revisited

    NASA Technical Reports Server (NTRS)

    Cleveland, Robin O.; Blackstock, David T.

    1996-01-01

    Nonlinear distortion of sonic booms propagating in the atmosphere is strongly affected by stratification and geometrical spreading. For a downward propagating sonic boom in a standard atmosphere, stratification and spreading cause a slowing down of nonlinear distortion. In certain cases a stage is reached where no further distortion takes place. When this happens, the waveform is said to be frozen. In previous work the authors argued that for most HSCT designs and flight conditions being considered, the sonic boom is not frozen when it reaches the ground. The criterion used was the value of the distortion distance x bar is a measure of the nonlinear distortion suffered by the wave (and is closely related to Hayes's E variable). The aircraft must be at an altitude greater than 27 km (80,000 ft) for x bar at the groun be within 95% of its asymptotic value. However, work reported here demonstrates that the ground waveform is much closer to the frozen state than indicated by the previous analysis. In the new analysis, duration of the sonic boom is used as the criterion for judging closeness of approach tz frozen state. In order for the duration of the sonic boom at the ground to be within 95% of its frozen value, the flight altitude of the aircraft needs to be only 15 km (45,000 ft).

  2. Backstepping Design of Adaptive Neural Fault-Tolerant Control for MIMO Nonlinear Systems.

    PubMed

    Gao, Hui; Song, Yongduan; Wen, Changyun

    2016-08-24

    In this paper, an adaptive controller is developed for a class of multi-input and multioutput nonlinear systems with neural networks (NNs) used as a modeling tool. It is shown that all the signals in the closed-loop system with the proposed adaptive neural controller are globally uniformly bounded for any external input in L[₀,∞]. In our control design, the upper bound of the NN modeling error and the gains of external disturbance are characterized by unknown upper bounds, which is more rational to establish the stability in the adaptive NN control. Filter-based modification terms are used in the update laws of unknown parameters to improve the transient performance. Finally, fault-tolerant control is developed to accommodate actuator failure. An illustrative example applying the adaptive controller to control a rigid robot arm shows the validation of the proposed controller.

  3. 75 FR 8968 - Draft Guidance for Industry on Adaptive Design Clinical Trials for Drugs and Biologics; Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-26

    ..., statistical, and regulatory aspects of a wide range of adaptive design clinical studies that can be proposed... design clinical trials (i.e., clinical, statistical, regulatory) call for special consideration, when to interact with FDA while planning and conducting adaptive design studies, what information to include in...

  4. Conceptual design for a user-friendly adaptive optics system at Lick Observatory

    SciTech Connect

    Bissinger, H.D.; Olivier, S.; Max, C.

    1996-03-08

    In this paper, we present a conceptual design for a general-purpose adaptive optics system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California`s Lick Observatory located on Mt. Hamilton near San Jose, California. The overall design goal for this system is to take the sodium-layer laser guide star adaptive optics technology out of the demonstration stage and to build a user-friendly astronomical tool. The emphasis will be on ease of calibration, improved stability and operational simplicity in order to allow the system to be run routinely by observatory staff. A prototype adaptive optics system and a 20 watt sodium-layer laser guide star system have already been built at Lawrence Livermore National Laboratory for use at Lick Observatory. The design presented in this paper is for a next- generation adaptive optics system that extends the capabilities of the prototype system into the visible with more degrees of freedom. When coupled with a laser guide star system that is upgraded to a power matching the new adaptive optics system, the combined system will produce diffraction-limited images for near-IR cameras. Atmospheric correction at wavelengths of 0.6-1 mm will significantly increase the throughput of the most heavily used facility instrument at Lick, the Kast Spectrograph, and will allow it to operate with smaller slit widths and deeper limiting magnitudes. 8 refs., 2 figs.

  5. Temporally adaptive sampling: a case study in rare species survey design with marbled salamanders (Ambystoma opacum).

    PubMed

    Charney, Noah D; Kubel, Jacob E; Eiseman, Charles S

    2015-01-01

    Improving detection rates for elusive species with clumped distributions is often accomplished through adaptive sampling designs. This approach can be extended to include species with temporally variable detection probabilities. By concentrating survey effort in years when the focal species are most abundant or visible, overall detection rates can be improved. This requires either long-term monitoring at a few locations where the species are known to occur or models capable of predicting population trends using climatic and demographic data. For marbled salamanders (Ambystoma opacum) in Massachusetts, we demonstrate that annual variation in detection probability of larvae is regionally correlated. In our data, the difference in survey success between years was far more important than the difference among the three survey methods we employed: diurnal surveys, nocturnal surveys, and dipnet surveys. Based on these data, we simulate future surveys to locate unknown populations under a temporally adaptive sampling framework. In the simulations, when pond dynamics are correlated over the focal region, the temporally adaptive design improved mean survey success by as much as 26% over a non-adaptive sampling design. Employing a temporally adaptive strategy costs very little, is simple, and has the potential to substantially improve the efficient use of scarce conservation funds.

  6. Temporally Adaptive Sampling: A Case Study in Rare Species Survey Design with Marbled Salamanders (Ambystoma opacum)

    PubMed Central

    Charney, Noah D.; Kubel, Jacob E.; Eiseman, Charles S.

    2015-01-01

    Improving detection rates for elusive species with clumped distributions is often accomplished through adaptive sampling designs. This approach can be extended to include species with temporally variable detection probabilities. By concentrating survey effort in years when the focal species are most abundant or visible, overall detection rates can be improved. This requires either long-term monitoring at a few locations where the species are known to occur or models capable of predicting population trends using climatic and demographic data. For marbled salamanders (Ambystoma opacum) in Massachusetts, we demonstrate that annual variation in detection probability of larvae is regionally correlated. In our data, the difference in survey success between years was far more important than the difference among the three survey methods we employed: diurnal surveys, nocturnal surveys, and dipnet surveys. Based on these data, we simulate future surveys to locate unknown populations under a temporally adaptive sampling framework. In the simulations, when pond dynamics are correlated over the focal region, the temporally adaptive design improved mean survey success by as much as 26% over a non-adaptive sampling design. Employing a temporally adaptive strategy costs very little, is simple, and has the potential to substantially improve the efficient use of scarce conservation funds. PMID:25799224

  7. Manipulation of zebrafish's orientation using artificial cilia in a microchannel with actively adaptive wall design.

    PubMed

    Mani, Karthick; Chang Chien, Tsung-Chun; Panigrahi, Bivas; Chen, Chia-Yuan

    2016-11-08

    The zebrafish is a powerful genetic model organism especially in the biomedical chapter for new drug discovery and development. The genetic toolbox which this vertebrate possesses opens a new window to investigate the etiology of human diseases with a high degree genetic similarity. Still, the requirements of laborious and time-consuming of contemporary zebrafish processing assays limit the procedure in carrying out such genetic screen at high throughput. Here, a zebrafish control scheme was initiated which includes the design and validation of a microfluidic platform to significantly increase the throughput and performance of zebrafish larvae manipulation using the concept of artificial cilia actuation. A moving wall design was integrated into this microfluidic platform first time in literature to accommodate zebrafish inside the microchannel from 1 day post-fertilization (dpf) to 6 dpf and can be further extended to 9 dpf for axial orientation control in a rotational range between 0 to 25 degrees at the minimum step of 2-degree increment in a stepwise manner. This moving wall feature was performed through the deflection of shape memory alloy wire embedded inside the microchannel controlled by the electrical waveforms with high accuracy.

  8. Design of a Fat-Based Adaptive Visual Servoing for Robots with Time Varying Uncertainties

    NASA Astrophysics Data System (ADS)

    Chien, Ming-Chih; Huang, An-Chyau

    2010-05-01

    Most present adaptive control strategies for visual servoing of robots have assumed that the unknown camera parameters, kinematics, and dynamics of visual servoing system should be linearly parameterized in the regressor matrix form. This is because the limitation of the traditional adaptive design in which the uncertainties should be time-invariant such that all time varying terms in the visual servoing system are collected inside the regressor matrix. However, derivation of the regressor matrix is tedious. In this article, a FAT (function approximation technique) based adaptive controller is designed for visual servo robots without the need for the regressor matrix. A Lyapunov-like analysis is used to justify the closed-loop stability and boundedness of internal signals. Moreover, the upper bounds of tracking errors in the transient state are also derived. Computer simulation results are presented to demonstrate the usefulness of the proposed scheme.

  9. Robust adaptive self-structuring fuzzy control design for nonaffine, nonlinear systems

    NASA Astrophysics Data System (ADS)

    Chen, Pin-Cheng; Wang, Chi-Hsu; Lee, Tsu-Tian

    2011-01-01

    In this article, a robust adaptive self-structuring fuzzy control (RASFC) scheme for the uncertain or ill-defined nonlinear, nonaffine systems is proposed. The RASFC scheme is composed of a robust adaptive controller and a self-structuring fuzzy controller. In the self-structuring fuzzy controller design, a novel self-structuring fuzzy system (SFS) is used to approximate the unknown plant nonlinearity, and the SFS can automatically grow and prune fuzzy rules to realise a compact fuzzy rule base. The robust adaptive controller is designed to achieve an L 2 tracking performance to stabilise the closed-loop system. This L 2 tracking performance can provide a clear expression of tracking error in terms of the sum of lumped uncertainty and external disturbance, which has not been shown in previous works. Finally, five examples are presented to show that the proposed RASFC scheme can achieve favourable tracking performance, yet heavy computational burden is relieved.

  10. An adaptive two-stage dose-response design method for establishing Proof of Concept

    PubMed Central

    Franchetti, Yoko; Anderson, Stewart J.; Sampson, Allan R.

    2013-01-01

    We propose an adaptive two-stage dose-response design where a pre-specified adaptation rule is used to add and/or drop treatment arms between the stages. We extend the multiple comparison procedures-modeling (MCP-Mod) approach into a two-stage design. In each stage, we use the same set of candidate dose-response models and test for a dose-response relationship or proof of concept (PoC) via model-associated statistics. The stage-wise test results are then combined to establish ‘global’ PoC using a conditional error function. Our simulation studies showed good and more robust power in our design method compared to conventional and fixed designs. PMID:23957520

  11. Notched spectrum: from probing waveforms to receive filters

    NASA Astrophysics Data System (ADS)

    Jiang, Yi; Gianelli, Christopher D.

    2013-05-01

    The increasing demand for wireless data services and communications is expanding the frequency footprint of both civilian and military wireless networks, and hence encroaches upon spectrum traditionally reserved for radar systems. To maximize spectral efficiency, it is desirable for a modern radar system to use waveforms with the ability to fit into tightly controlled spectral regions, which requires the formation of nulls with required notching levels on prescribed frequency stop-bands. Additionally, the waveform should posses a low peak-to-average ratio (PAR), and have good auto-correlation performance. In this work, we propose a novel method for the design of such a waveform using alternating convex optimization. The core module of the proposed algorithm is a fast Fourier transform, which makes the algorithm quite efficient and can handle waveform designs with up to 105 samples. Moreover, our algorithm can achieve a flexible tradeoff between PAR and reduced pass band ripple. A simple application in synthetic aperture radar is considered to highlight the performance of the design algorithm.

  12. Transient analysis of an adaptive system for optimization of design parameters

    NASA Technical Reports Server (NTRS)

    Bayard, D. S.

    1992-01-01

    Averaging methods are applied to analyzing and optimizing the transient response associated with the direct adaptive control of an oscillatory second-order minimum-phase system. The analytical design methods developed for a second-order plant can be applied with some approximation to a MIMO flexible structure having a single dominant mode.

  13. Development of an Assistance Environment for Tutors Based on a Co-Adaptive Design Approach

    ERIC Educational Resources Information Center

    Lavoue, Elise; George, Sebastien; Prevot, Patrick

    2012-01-01

    In this article, we present a co-adaptive design approach named TE-Cap (Tutoring Experience Capitalisation) that we applied for the development of an assistance environment for tutors. Since tasks assigned to tutors in educational contexts are not well defined, we are developing an environment which responds to needs which are not precisely…

  14. Can Approaches to Research in Art and Design Be Beneficially Adapted for Research into Higher Education?

    ERIC Educational Resources Information Center

    Trowler, Paul

    2013-01-01

    This paper examines the research practices in Art and Design that are distinctively different from those common in research into higher education outside those fields. It considers whether and what benefit could be derived from their adaptation by the latter. The paper also examines the factors that are conducive and obstructive to adaptive…

  15. Direct and Inverse Problems of Item Pool Design for Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Belov, Dmitry I.; Armstrong, Ronald D.

    2009-01-01

    The recent literature on computerized adaptive testing (CAT) has developed methods for creating CAT item pools from a large master pool. Each CAT pool is designed as a set of nonoverlapping forms reflecting the skill levels of an assumed population of test takers. This article presents a Monte Carlo method to obtain these CAT pools and discusses…

  16. Lessons Learned in Designing and Implementing a Computer-Adaptive Test for English

    ERIC Educational Resources Information Center

    Burston, Jack; Neophytou, Maro

    2014-01-01

    This paper describes the lessons learned in designing and implementing a computer-adaptive test (CAT) for English. The early identification of students with weak L2 English proficiency is of critical importance in university settings that have compulsory English language course graduation requirements. The most efficient means of diagnosing the L2…

  17. Full waveform modelling and misfit calculation using the VERCE platform

    NASA Astrophysics Data System (ADS)

    Garth, Thomas; Spinuso, Alessandro; Casarotti, Emanuele; Magnoni, Federica; Krischner, Lion; Igel, Heiner; Schwichtenberg, Horst; Frank, Anton; Vilotte, Jean-Pierre; Rietbrock, Andreas

    2016-04-01

    In recent years the increasing resolution of seismic imagining by full waveform inversion has opened new research perspectives and practices. These methods rely on harnessing the computational power of large supercomputers and new storage capabilities, to run large parallel codes to simulate the seismic wave field in three-dimensional geological settings. The VERCE platform is designed to make these full waveform techniques accessible to a far wider spectrum of the seismological community. VERCE empowers a broad base of seismology researchers to harvest the new opportunities provided by well-established high-performance wave simulation codes such as SPECFEM3D. It meets a range of seismic research needs by eliminating the technical difficulties associated with using these codes, allowing users to focus on their research questions. VERCE delivers this power to seismologists through its science gateway, supporting wave simulation codes on each of the provided computing resources. Users can design their waveform simulation scenarios making use of a library of pre-loaded meshes and velocity models, and services for selecting earthquake focal mechanisms, seismic stations and recorded waveforms from existing catalogues, such as the GCMT catalogue, and FDSN data sources. They can also supply their own mesh, velocity model, earthquake catalogue and seismic observations. They can submit the simulations onto different computing resources, where VERCE provides codes that are tuned and supported for those resources. The simulations can currently be run on a range of European supercomputers in the PRACE network, including superMUC at LRZ, GALILEO at CINECA and on selected resources like Drachenfels at SCAI and within the EGI network. The gateway automates and looks after all these stages, but supplies seismologists with a provenance system that allows them to manage a large series of runs, review progress, and explore the results. The platform automates misfit analysis between

  18. Design of artificial genetic regulatory networks with multiple delayed adaptive responses*

    NASA Astrophysics Data System (ADS)

    Kaluza, Pablo; Inoue, Masayo

    2016-06-01

    Genetic regulatory networks with adaptive responses are widely studied in biology. Usually, models consisting only of a few nodes have been considered. They present one input receptor for activation and one output node where the adaptive response is computed. In this work, we design genetic regulatory networks with many receptors and many output nodes able to produce delayed adaptive responses. This design is performed by using an evolutionary algorithm of mutations and selections that minimizes an error function defined by the adaptive response in signal shapes. We present several examples of network constructions with a predefined required set of adaptive delayed responses. We show that an output node can have different kinds of responses as a function of the activated receptor. Additionally, complex network structures are presented since processing nodes can be involved in several input-output pathways. Supplementary material in the form of one nets file available from the Journal web page at http://dx.doi.org/10.1140/epjb/e2016-70172-9

  19. Analysis and design of a high power laser adaptive phased array transmitter

    NASA Technical Reports Server (NTRS)

    Mevers, G. E.; Soohoo, J. F.; Winocur, J.; Massie, N. A.; Southwell, W. H.; Brandewie, R. A.; Hayes, C. L.

    1977-01-01

    The feasibility of delivering substantial quantities of optical power to a satellite in low earth orbit from a ground based high energy laser (HEL) coupled to an adaptive antenna was investigated. Diffraction effects, atmospheric transmission efficiency, adaptive compensation for atmospheric turbulence effects, including the servo bandwidth requirements for this correction, and the adaptive compensation for thermal blooming were examined. To evaluate possible HEL sources, atmospheric investigations were performed for the CO2, (C-12)(O-18)2 isotope, CO and DF wavelengths using output antenna locations of both sea level and mountain top. Results indicate that both excellent atmospheric and adaption efficiency can be obtained for mountain top operation with a micron isotope laser operating at 9.1 um, or a CO laser operating single line (P10) at about 5.0 (C-12)(O-18)2um, which was a close second in the evaluation. Four adaptive power transmitter system concepts were generated and evaluated, based on overall system efficiency, reliability, size and weight, advanced technology requirements and potential cost. A multiple source phased array was selected for detailed conceptual design. The system uses a unique adaption technique of phase locking independent laser oscillators which allows it to be both relatively inexpensive and most reliable with a predicted overall power transfer efficiency of 53%.

  20. Neural network-based adaptive controller design of robotic manipulators with an observer.

    PubMed

    Sun, F; Sun, Z; Woo, P Y

    2001-01-01

    A neural network (NN)-based adaptive controller with an observer is proposed for the trajectory tracking of robotic manipulators with unknown dynamics nonlinearities. It is assumed that the robotic manipulator has only joint angle position measurements. A linear observer is used to estimate the robot joint angle velocity, while NNs are employed to further improve the control performance of the controlled system through approximating the modified robot dynamics function. The adaptive controller for robots with an observer can guarantee the uniform ultimate bounds of the tracking errors and the observer errors as well as the bounds of the NN weights. For performance comparisons, the conventional adaptive algorithm with an observer using linearity in parameters of the robot dynamics is also developed in the same control framework as the NN approach for online approximating unknown nonlinearities of the robot dynamics. Main theoretical results for designing such an observer-based adaptive controller with the NN approach using multilayer NNs with sigmoidal activation functions, as well as with the conventional adaptive approach using linearity in parameters of the robot dynamics are given. The performance comparisons between the NN approach and the conventional adaptation approach with an observer is carried out to show the advantages of the proposed control approaches through simulation studies.

  1. E-ELT M4 adaptive unit final design and construction: a progress report

    NASA Astrophysics Data System (ADS)

    Biasi, Roberto; Manetti, Mauro; Andrighettoni, Mario; Angerer, Gerald; Pescoller, Dietrich; Patauner, Christian; Gallieni, Daniele; Tintori, Matteo; Mantegazza, Marco; Fumi, Pierluigi; Lazzarini, Paolo; Briguglio, Runa; Xompero, Marco; Pariani, Giorgio; Riccardi, Armando; Vernet, Elise; Pettazzi, Lorenzo; Lilley, Paul; Cayrel, Marc

    2016-07-01

    The E-ELT M4 adaptive unit is a fundamental part of the E-ELT: it provides the facility level adaptive optics correction that compensates the wavefront distortion induced by atmospheric turbulence and partially corrects the structural deformations caused by wind. The unit is based on the contactless, voice-coil technology already successfully deployed on several large adaptive mirrors, like the LBT, Magellan and VLT adaptive secondary mirrors. It features a 2.4m diameter flat mirror, controlled by 5316 actuators and divided in six segments. The reference structure is monolithic and the cophasing between the segments is guaranteed by the contactless embedded metrology. The mirror correction commands are usually transferred as modal amplitudes, that are checked by the M4 controller through a smart real-time algorithm that is capable to handle saturation effects. A large hexapod provides the fine positioning of the unit, while a rotational mechanism allows switching between the two Nasmyth foci. The unit has entered the final design and construction phase in July 2015, after an advanced preliminary design. The final design review is planned for fall 2017; thereafter, the unit will enter the construction and test phase. Acceptance in Europe after full optical calibration is planned for 2022, while the delivery to Cerro Armazones will occur in 2023. Even if the fundamental concept has remained unchanged with respect to the other contactless large deformable mirrors, the specific requirements of the E-ELT unit posed new design challenges that required very peculiar solutions. Therefore, a significant part of the design phase has been focused on the validation of the new aspects, based on analysis, numerical simulations and experimental tests. Several experimental tests have been executed on the Demonstration Prototype, which is the 222 actuators prototype developed in the frame of the advanced preliminary design. We present the main project phases, the current design

  2. Lightning current waveform measuring system

    NASA Technical Reports Server (NTRS)

    Wojtasinski, R. J.; Fuchs, J. C.; Grove, C. H. (Inventor)

    1978-01-01

    An apparatus is described for monitoring current waveforms produced by lightning strikes which generate currents in an elongated cable. These currents are converted to voltages and to light waves for being transmitted over an optical cable to a remote location. At the remote location, the waves are reconstructed back into electrical waves for being stored into a memory. The information is stored within the memory with a timing signal so that only different signals need be stored in order to reconstruct the wave form.

  3. Fractal characteristics for binary noise radar waveform

    NASA Astrophysics Data System (ADS)

    Li, Bing C.

    2016-05-01

    Noise radars have many advantages over conventional radars and receive great attentions recently. The performance of a noise radar is determined by its waveforms. Investigating characteristics of noise radar waveforms has significant value for evaluating noise radar performance. In this paper, we use binomial distribution theory to analyze general characteristics of binary phase coded (BPC) noise waveforms. Focusing on aperiodic autocorrelation function, we demonstrate that the probability distributions of sidelobes for a BPC noise waveform depend on the distances of these sidelobes to the mainlobe. The closer a sidelobe to the mainlobe, the higher the probability for this sidelobe to be a maximum sidelobe. We also develop Monte Carlo framework to explore the characteristics that are difficult to investigate analytically. Through Monte Carlo experiments, we reveal the Fractal relationship between the code length and the maximum sidelobe value for BPC waveforms, and propose using fractal dimension to measure noise waveform performance.

  4. Design and progress toward a multi-conjugate adaptive optics system for distributed aberration correction

    SciTech Connect

    Baker, K; Olivier, S; Tucker, J; Silva, D; Gavel, D; Lim, R; Gratrix, E

    2004-08-17

    This article investigates the use of a multi-conjugate adaptive optics system to improve the field-of-view for the system. The emphasis of this research is to develop techniques to improve the performance of optical systems with applications to horizontal imaging. The design and wave optics simulations of the proposed system are given. Preliminary results from the multi-conjugate adaptive optics system are also presented. The experimental system utilizes a liquid-crystal spatial light modulator and an interferometric wave-front sensor for correction and sensing of the phase aberrations, respectively.

  5. DI2ADEM: an adaptive hypermedia designed to improve access to relevant medical information.

    PubMed

    Pagesy, R; Soula, G; Fieschi, M

    2000-01-01

    The World Wide Web (web) provides the same type of information to widely different users and these users must then find the information suitable for their use in the package offered. The authors present the DI2ADEM project designed to take the user into account and intended to provide this user with appropriate medical information. To do that, DI2ADEM is suggesting an adaptive hypermedia based on the management of a meta-knowledge of the user and a knowledge of the information that can be circulated. An adaptive hypermedia prototype devoted to paediatric oncology was implemented on the intranet network of a university hospital.

  6. Design of adaptive filter amplifier in UV communication based on DSP

    NASA Astrophysics Data System (ADS)

    Lv, Zhaoshun; Wu, Hanping; Li, Junyu

    2016-10-01

    According to the problem of the weak signal at receiving end in UV communication, we design a high gain, continuously adjustable adaptive filter amplifier. Based on proposing overall technical indicators and analyzing its working principle of the signal amplifier, we use chip LMH6629MF and two chips of AD797BN to achieve three-level cascade amplification. And apply hardware of DSP TMS320VC5509A to implement digital filtering. Design and verification by Multisim, Protel 99SE and CCS, the results show that: the amplifier can realize continuously adjustable amplification from 1000 to 10000 times without distortion. Magnification error is <=%4@1000 10000. And equivalent input noise voltage of amplification circuit is <=6 nV/ √Hz @30KHz 45KHz, and realizing function of adaptive filtering. The design provides theoretical reference and technical support for the UV weak signal processing.

  7. Adjoint-Based Algorithms for Adaptation and Design Optimizations on Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Nielsen, Eric J.

    2006-01-01

    Schemes based on discrete adjoint algorithms present several exciting opportunities for significantly advancing the current state of the art in computational fluid dynamics. Such methods provide an extremely efficient means for obtaining discretely consistent sensitivity information for hundreds of design variables, opening the door to rigorous, automated design optimization of complex aerospace configuration using the Navier-Stokes equation. Moreover, the discrete adjoint formulation provides a mathematically rigorous foundation for mesh adaptation and systematic reduction of spatial discretization error. Error estimates are also an inherent by-product of an adjoint-based approach, valuable information that is virtually non-existent in today's large-scale CFD simulations. An overview of the adjoint-based algorithm work at NASA Langley Research Center is presented, with examples demonstrating the potential impact on complex computational problems related to design optimization as well as mesh adaptation.

  8. Design and Inference for the Intent to Treat Principle using Adaptive Treatment Strategies and Sequential Randomization

    PubMed Central

    Dawson, Ree; Lavori, Philip W.

    2015-01-01

    Nonadherence to assigned treatment jeopardizes the power and interpretability of intent-to-treat comparisons from clinical trial data and continues to be an issue for effectiveness studies, despite their pragmatic emphasis. We posit that new approaches to design need to complement developments in methods for causal inference to address nonadherence, in both experimental and practice settings. This paper considers the conventional study design for psychiatric research and other medical contexts, in which subjects are randomized to treatments that are fixed throughout the trial and presents an alternative that converts the fixed treatments into an adaptive intervention that reflects best practice. The key element is the introduction of an adaptive decision point midway into the study to address a patient's reluctance to remain on treatment before completing a full-length trial of medication. The clinical uncertainty about the appropriate adaptation prompts a second randomization at the new decision point to evaluate relevant options. Additionally, the standard ‘all-or-none’ principal stratification (PS) framework is applied to the first stage of the design to address treatment discontinuation that occurs too early for a mid-trial adaptation. Drawing upon the adaptive intervention features, we develop assumptions to identify the PS causal estimand and introduce restrictions on outcome distributions to simplify Expectation-Maximization calculations. We evaluate the performance of the PS setup, with particular attention to the role played by a binary covariate. The results emphasize the importance of collecting covariate data for use in design and analysis. We consider the generality of our approach beyond the setting of psychiatric research. PMID:25581413

  9. High-precision triangular-waveform generator

    DOEpatents

    Mueller, T.R.

    1981-11-14

    An ultra-linear ramp generator having separately programmable ascending and decending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  10. A New Approach to Radar Waveform Design

    DTIC Science & Technology

    2007-08-24

    published in peer-reviewed journals (N/A for none) I.Gladkova, D.Chebanov, On a new extension of Wilcox’s Method, WSEAS Transactions on Mathematics, Vol.3, p...Conference RADAR 2004, 18-22 October 2004, Toulouse, France I.Gladkova, D.Chebanov, On a new extension of Wilcox’s Method invited paper, 5th WSEAS ...extension of Wilcox’s Method, WSEAS Trans- actions on Mathematics, Vol.3, p.244–249, April 2004. 2. I.Gladkova, A Family of Frequency Modulated

  11. Integrated Coding and Waveform Design Study.

    DTIC Science & Technology

    1980-08-01

    Ou... Dec.de.,.. ... .1. . 10 0o - 2 - - - 7- - - 0 1 1 CcNLT OS RI ERIFRRINBT(B Fiur 8.......2 ecoded ....... Perfomanc ...f. a Tw...10 A: iiSW fit E~rro" Rate 3: No Inner Coda Co vlutional outer ’ i . . . . . . D ecoder , R-0.5 0 I C: Sinary Inner 0ecode...Convolut~ional Outer Decoder, R-O.25 ’. .l . . .. . . .. . . . . . 0: Channel M easurem ent Tinner Decoder, - 9Con cu citon al Oute r ecode , R

  12. Design Framework for an Adaptive MOOC Enhanced by Blended Learning: Supplementary Training and Personalized Learning for Teacher Professional Development

    ERIC Educational Resources Information Center

    Gynther, Karsten

    2016-01-01

    The research project has developed a design framework for an adaptive MOOC that complements the MOOC format with blended learning. The design framework consists of a design model and a series of learning design principles which can be used to design in-service courses for teacher professional development. The framework has been evaluated by…

  13. Carotid arterial blood pressure waveform monitoring using a portable ultrasound system.

    PubMed

    Joohyun Seo; Pietrangelo, Sabino J; Hae-Seung Lee; Sodini, Charles G

    2015-08-01

    This work presents a non-invasive arterial blood pressure (ABP) waveform monitoring technique using ultrasound. A portable ultrasound system to excite ultrasound transducers and acquire data is designed with off-the-shelf components. The insonation angles are identified using a vector Doppler technique based on the cosine dependency of the Doppler signals. The pulse pressure of an estimated waveform at the left common carotid artery is compared to the standard sphygmomanometer measurement in a clinical test. The estimated carotid ABP waveform shows excellent agreement to the finger ABP waveform with expected discrepancy of the systolic peak shape due to different measurement sites. The proposed method also tracks slow blood pressure fluctuations. This validation on human subjects shows potential for a noninvasive blood pressure waveform monitoring device at central arterial sites.

  14. Ultrabroadband radio-frequency arbitrary waveform generation with high-speed phase and amplitude modulation capability.

    PubMed

    Rashidinejad, Amir; Leaird, Daniel E; Weiner, Andrew M

    2015-05-04

    We introduce a novel photonic-assisted ultrabroadband radio-frequency arbitrary waveform generation setup capable of high-speed phase and amplitude modulation of the individual arbitrary waveforms. The waveform generator is based on an optical interferometer, within which a high-resolution optical pulse shaper and integrated optic phase and intensity modulators are placed, followed by frequency-to-time mapping. The phase and amplitude of each ultrabroadband waveform within the generated sequence can be continuously tuned by adjusting the driving voltages applied to the phase and intensity modulator pair, hence overcoming the slow update speed of conventional spatial light modulator-based pulse shapers. Moreover, this data modulation is completely independent from and does not interfere with RF waveform design. Programmable ultrabroadband RF sequences, spanning more than 4.7 octaves from 2 to 52 GHz, are modulated with real-time data in up to 16 level, M-ary phase-shift keying and quadrature amplitude modulation formats.

  15. Design Process of Flight Vehicle Structures for a Common Bulkhead and an MPCV Spacecraft Adapter

    NASA Technical Reports Server (NTRS)

    Aggarwal, Pravin; Hull, Patrick V.

    2015-01-01

    Design and manufacturing space flight vehicle structures is a skillset that has grown considerably at NASA during that last several years. Beginning with the Ares program and followed by the Space Launch System (SLS); in-house designs were produced for both the Upper Stage and the SLS Multipurpose crew vehicle (MPCV) spacecraft adapter. Specifically, critical design review (CDR) level analysis and flight production drawing were produced for the above mentioned hardware. In particular, the experience of this in-house design work led to increased manufacturing infrastructure for both Marshal Space Flight Center (MSFC) and Michoud Assembly Facility (MAF), improved skillsets in both analysis and design, and hands on experience in building and testing (MSA) full scale hardware. The hardware design and development processes from initiation to CDR and finally flight; resulted in many challenges and experiences that produced valuable lessons. This paper builds on these experiences of NASA in recent years on designing and fabricating flight hardware and examines the design/development processes used, as well as the challenges and lessons learned, i.e. from the initial design, loads estimation and mass constraints to structural optimization/affordability to release of production drawing to hardware manufacturing. While there are many documented design processes which a design engineer can follow, these unique experiences can offer insight into designing hardware in current program environments and present solutions to many of the challenges experienced by the engineering team.

  16. An implementable digital adaptive flight controller designed using stabilized single stage algorithms

    NASA Technical Reports Server (NTRS)

    Kaufman, H.; Alag, G.

    1975-01-01

    Simple mechanical linkages have not solved the many control problems associated with high performance aircraft maneuvering throughout a wide flight envelope. One procedure for retaining uniform handling qualities over such an envelope is to implement a digital adaptive controller. Towards such an implementation an explicit adaptive controller which makes direct use of on-line parameter identification, has been developed and applied to both linearized and nonlinear equations of motion for a typical fighter aircraft. This controller is composed of an on-line weighted least squares parameter identifier, a Kalman state filter, and a model following control law designed using single stage performance indices. Simulation experiments with realistic measurement noise indicate that the proposed adaptive system has the potential for on-board implementation.

  17. An Integrated Systems Approach to Designing Climate Change Adaptation Policy in Water Resources

    NASA Astrophysics Data System (ADS)

    Ryu, D.; Malano, H. M.; Davidson, B.; George, B.

    2014-12-01

    Climate change projections are characterised by large uncertainties with rainfall variability being the key challenge in designing adaptation policies. Climate change adaptation in water resources shows all the typical characteristics of 'wicked' problems typified by cognitive uncertainty as new scientific knowledge becomes available, problem instability, knowledge imperfection and strategic uncertainty due to institutional changes that inevitably occur over time. Planning that is characterised by uncertainties and instability requires an approach that can accommodate flexibility and adaptive capacity for decision-making. An ability to take corrective measures in the event that scenarios and responses envisaged initially derive into forms at some future stage. We present an integrated-multidisciplinary and comprehensive framework designed to interface and inform science and decision making in the formulation of water resource management strategies to deal with climate change in the Musi Catchment of Andhra Pradesh, India. At the core of this framework is a dialogue between stakeholders, decision makers and scientists to define a set of plausible responses to an ensemble of climate change scenarios derived from global climate modelling. The modelling framework used to evaluate the resulting combination of climate scenarios and adaptation responses includes the surface and groundwater assessment models (SWAT & MODFLOW) and the water allocation modelling (REALM) to determine the water security of each adaptation strategy. Three climate scenarios extracted from downscaled climate models were selected for evaluation together with four agreed responses—changing cropping patterns, increasing watershed development, changing the volume of groundwater extraction and improving irrigation efficiency. Water security in this context is represented by the combination of level of water availability and its associated security of supply for three economic activities (agriculture

  18. Layer-based buffer aware rate adaptation design for SHVC video streaming

    NASA Astrophysics Data System (ADS)

    Gudumasu, Srinivas; Hamza, Ahmed; Asbun, Eduardo; He, Yong; Ye, Yan

    2016-09-01

    This paper proposes a layer based buffer aware rate adaptation design which is able to avoid abrupt video quality fluctuation, reduce re-buffering latency and improve bandwidth utilization when compared to a conventional simulcast based adaptive streaming system. The proposed adaptation design schedules DASH segment requests based on the estimated bandwidth, dependencies among video layers and layer buffer fullness. Scalable HEVC video coding is the latest state-of-art video coding technique that can alleviate various issues caused by simulcast based adaptive video streaming. With scalable coded video streams, the video is encoded once into a number of layers representing different qualities and/or resolutions: a base layer (BL) and one or more enhancement layers (EL), each incrementally enhancing the quality of the lower layers. Such layer based coding structure allows fine granularity rate adaptation for the video streaming applications. Two video streaming use cases are presented in this paper. The first use case is to stream HD SHVC video over a wireless network where available bandwidth varies, and the performance comparison between proposed layer-based streaming approach and conventional simulcast streaming approach is provided. The second use case is to stream 4K/UHD SHVC video over a hybrid access network that consists of a 5G millimeter wave high-speed wireless link and a conventional wired or WiFi network. The simulation results verify that the proposed layer based rate adaptation approach is able to utilize the bandwidth more efficiently. As a result, a more consistent viewing experience with higher quality video content and minimal video quality fluctuations can be presented to the user.

  19. Noninvasive arterial blood pressure waveform monitoring using two- element ultrasound system.

    PubMed

    Seo, Joohyun; Pietrangelo, Sabino J; Lee, Hae-Seung; Sodini, Charles G

    2015-04-01

    This work details noninvasive arterial blood pressure (ABP) waveform estimation based on an arterial vessel cross-sectional area measurement combined with an elasticity measurement of the vessel, represented by pulse wave velocity (PWV), using a two-element ultrasound system. The overall ABP waveform estimation is validated in a custom-designed experimental setup mimicking the heart and an arterial vessel segment with two single element transducers, assuming a constant hemodynamic system. The estimation of local PWV using the flow-area method produces unbiased elasticity estimation of the tube in a pressure waveform comparison. The measured PWV using 16 cardiac cycles of data is 8.47 + 0.63 m/s with an associated scaling error of -1.56 + 14.0% in a direct pressure waveform comparison, showing negligible bias error on average. The distension waveform obtained from a complex cross-correlation model estimator (C3M) reliably traces small pressure changes reflected by the diameter change. The excellent agreement of an estimated pressure waveform to the reference pressure waveform suggests the promising potential of a readily available, inexpensive, and portable ABP waveform monitoring device.

  20. Opportunities and Challenges for Drug Development: Public-Private Partnerships, Adaptive Designs and Big Data.

    PubMed

    Yildirim, Oktay; Gottwald, Matthias; Schüler, Peter; Michel, Martin C

    2016-01-01

    Drug development faces the double challenge of increasing costs and increasing pressure on pricing. To avoid that lack of perceived commercial perspective will leave existing medical needs unmet, pharmaceutical companies and many other stakeholders are discussing ways to improve the efficiency of drug Research and Development. Based on an international symposium organized by the Medical School of the University of Duisburg-Essen (Germany) and held in January 2016, we discuss the opportunities and challenges of three specific areas, i.e., public-private partnerships, adaptive designs and big data. Public-private partnerships come in many different forms with regard to scope, duration and type and number of participants. They range from project-specific collaborations to strategic alliances to large multi-party consortia. Each of them offers specific opportunities and faces distinct challenges. Among types of collaboration, investigator-initiated studies are becoming increasingly popular but have legal, ethical, and financial implications. Adaptive trial designs are also increasingly discussed. However, adaptive should not be used as euphemism for the repurposing of a failed trial; rather it requires carefully planning and specification before a trial starts. Adaptive licensing can be a counter-part of adaptive trial design. The use of Big Data is another opportunity to leverage existing information into knowledge useable for drug discovery and development. Respecting limitations of informed consent and privacy is a key challenge in the use of Big Data. Speakers and participants at the symposium were convinced that appropriate use of the above new options may indeed help to increase the efficiency of future drug development.

  1. Opportunities and Challenges for Drug Development: Public–Private Partnerships, Adaptive Designs and Big Data

    PubMed Central

    Yildirim, Oktay; Gottwald, Matthias; Schüler, Peter; Michel, Martin C.

    2016-01-01

    Drug development faces the double challenge of increasing costs and increasing pressure on pricing. To avoid that lack of perceived commercial perspective will leave existing medical needs unmet, pharmaceutical companies and many other stakeholders are discussing ways to improve the efficiency of drug Research and Development. Based on an international symposium organized by the Medical School of the University of Duisburg-Essen (Germany) and held in January 2016, we discuss the opportunities and challenges of three specific areas, i.e., public–private partnerships, adaptive designs and big data. Public–private partnerships come in many different forms with regard to scope, duration and type and number of participants. They range from project-specific collaborations to strategic alliances to large multi-party consortia. Each of them offers specific opportunities and faces distinct challenges. Among types of collaboration, investigator-initiated studies are becoming increasingly popular but have legal, ethical, and financial implications. Adaptive trial designs are also increasingly discussed. However, adaptive should not be used as euphemism for the repurposing of a failed trial; rather it requires carefully planning and specification before a trial starts. Adaptive licensing can be a counter-part of adaptive trial design. The use of Big Data is another opportunity to leverage existing information into knowledge useable for drug discovery and development. Respecting limitations of informed consent and privacy is a key challenge in the use of Big Data. Speakers and participants at the symposium were convinced that appropriate use of the above new options may indeed help to increase the efficiency of future drug development. PMID:27999543

  2. Dynamic experiment design regularization approach to adaptive imaging with array radar/SAR sensor systems.

    PubMed

    Shkvarko, Yuriy; Tuxpan, José; Santos, Stewart

    2011-01-01

    We consider a problem of high-resolution array radar/SAR imaging formalized in terms of a nonlinear ill-posed inverse problem of nonparametric estimation of the power spatial spectrum pattern (SSP) of the random wavefield scattered from a remotely sensed scene observed through a kernel signal formation operator and contaminated with random Gaussian noise. First, the Sobolev-type solution space is constructed to specify the class of consistent kernel SSP estimators with the reproducing kernel structures adapted to the metrics in such the solution space. Next, the "model-free" variational analysis (VA)-based image enhancement approach and the "model-based" descriptive experiment design (DEED) regularization paradigm are unified into a new dynamic experiment design (DYED) regularization framework. Application of the proposed DYED framework to the adaptive array radar/SAR imaging problem leads to a class of two-level (DEED-VA) regularized SSP reconstruction techniques that aggregate the kernel adaptive anisotropic windowing with the projections onto convex sets to enforce the consistency and robustness of the overall iterative SSP estimators. We also show how the proposed DYED regularization method may be considered as a generalization of the MVDR, APES and other high-resolution nonparametric adaptive radar sensing techniques. A family of the DYED-related algorithms is constructed and their effectiveness is finally illustrated via numerical simulations.

  3. On Mixed Data and Event Driven Design for Adaptive-Critic-Based Nonlinear $H∞ Control.

    PubMed

    Wang, Ding; Mu, Chaoxu; Liu, Derong; Ma, Hongwen

    2017-02-01

    In this paper, based on the adaptive critic learning technique, the H∞ control for a class of unknown nonlinear dynamic systems is investigated by adopting a mixed data and event driven design approach. The nonlinear H∞ control problem is formulated as a two-player zero-sum differential game and the adaptive critic method is employed to cope with the data-based optimization. The novelty lies in that the data driven learning identifier is combined with the event driven design formulation, in order to develop the adaptive critic controller, thereby accomplishing the nonlinear H∞ control. The event driven optimal control law and the time driven worst case disturbance law are approximated by constructing and tuning a critic neural network. Applying the event driven feedback control, the closed-loop system is built with stability analysis. Simulation studies are conducted to verify the theoretical results and illustrate the control performance. It is significant to observe that the present research provides a new avenue of integrating data-based control and event-triggering mechanism into establishing advanced adaptive critic systems.

  4. Implementation of time-efficient adaptive sampling function design for improved undersampled MRI reconstruction

    NASA Astrophysics Data System (ADS)

    Choi, Jinhyeok; Kim, Hyeonjin

    2016-12-01

    To improve the efficacy of undersampled MRI, a method of designing adaptive sampling functions is proposed that is simple to implement on an MR scanner and yet effectively improves the performance of the sampling functions. An approximation of the energy distribution of an image (E-map) is estimated from highly undersampled k-space data acquired in a prescan and efficiently recycled in the main scan. An adaptive probability density function (PDF) is generated by combining the E-map with a modeled PDF. A set of candidate sampling functions are then prepared from the adaptive PDF, among which the one with maximum energy is selected as the final sampling function. To validate its computational efficiency, the proposed method was implemented on an MR scanner, and its robust performance in Fourier-transform (FT) MRI and compressed sensing (CS) MRI was tested by simulations and in a cherry tomato. The proposed method consistently outperforms the conventional modeled PDF approach for undersampling ratios of 0.2 or higher in both FT-MRI and CS-MRI. To fully benefit from undersampled MRI, it is preferable that the design of adaptive sampling functions be performed online immediately before the main scan. In this way, the proposed method may further improve the efficacy of the undersampled MRI.

  5. A versatile waveform generator for testing neuroelectric signal processors.

    PubMed

    Kohn, A F

    1989-08-01

    A multi-channel waveform generator was designed for testing neuroelectric signal processors. Smooth transient signals that resemble action potentials or evoked potentials are generated by a second order switched capacitor filter excited by brief rectangular pulses. The choice of an integrated circuit switched capacitor filter simplified the design by circumventing some of the disadvantages of conventional active filters. The waveform generator is versatile, with several signal parameters being independently adjustable from front panel controls: duration, waveshape, latency, amplitude and signal-to-noise ratio. The generator has been used for testing evoked potential acquisition and processing systems, for evaluating the effects of analog filters on evoked potentials and for testing systems designed to detect and classify trains of multi-unit action potentials.

  6. Design of signal-adapted multidimensional lifting scheme for lossy coding.

    PubMed

    Gouze, Annabelle; Antonini, Marc; Barlaud, Michel; Macq, Benoît

    2004-12-01

    This paper proposes a new method for the design of lifting filters to compute a multidimensional nonseparable wavelet transform. Our approach is stated in the general case, and is illustrated for the 2-D separable and for the quincunx images. Results are shown for the JPEG2000 database and for satellite images acquired on a quincunx sampling grid. The design of efficient quincunx filters is a difficult challenge which has already been addressed for specific cases. Our approach enables the design of less expensive filters adapted to the signal statistics to enhance the compression efficiency in a more general case. It is based on a two-step lifting scheme and joins the lifting theory with Wiener's optimization. The prediction step is designed in order to minimize the variance of the signal, and the update step is designed in order to minimize a reconstruction error. Application for lossy compression shows the performances of the method.

  7. Goldstone Solar System Radar Waveform Generator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    Due to distances and relative motions among the transmitter, target object, and receiver, the time-base between any transmitted and received signal will undergo distortion. Pre-distortion of the transmitted signal to compensate for this time-base distortion allows reception of an undistorted signal. In most radar applications, an arbitrary waveform generator (AWG) would be used to store the pre-calculated waveform and then play back this waveform during transmission. The Goldstone Solar System Radar (GSSR), however, has transmission durations that exceed the available memory storage of such a device. A waveform generator capable of real-time pre-distortion of a radar waveform to a given time-base distortion function is needed. To pre-distort the transmitted signal, both the baseband radar waveform and the RF carrier must be modified. In the GSSR, this occurs at the up-conversion mixing stage to an intermediate frequency (IF). A programmable oscillator (PO) is used to generate the IF along with a time-varying phase component that matches the time-base distortion of the RF carrier. This serves as the IF input to the waveform generator where it is mixed with a baseband radar waveform whose time-base has been distorted to match the given time-base distortion function producing the modulated IF output. An error control feedback loop is used to precisely control the time-base distortion of the baseband waveform, allowing its real-time generation. The waveform generator produces IF modulated radar waveforms whose time-base has been pre-distorted to match a given arbitrary function. The following waveforms are supported: continuous wave (CW), frequency hopped (FH), binary phase code (BPC), and linear frequency modulation (LFM). The waveform generator takes as input an IF with a time varying phase component that matches the time-base distortion of the carrier. The waveform generator supports interconnection with deep-space network (DSN) timing and frequency standards, and

  8. Analysis of Waveform Errors in Millimeter-Wave Lfmcw Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Wang, Wenqin

    2006-11-01

    In remote sensing applications, there is a special interest in the lightweight, cost effective, and high resolution imaging sensors. The combination of linearly frequency modulated continuous wave (LFMCW) technology and synthetic aperture radar (SAR) technique can lead to such a sensor. This paper concentrates on the analysis of waveform errors in millimeter-wave (MMW) LFMCW SAR. The generating scheme of millimeter-wave LFMCW waveforms with phase locked loop (PLL) and direct digital synthesizer (DDS) combined frequency synthesizer is investigated. The impacts of quantization errors, spurs, and frequency nonlinearities are analyzed. Simulation results show that the quality of LFMCW waveforms has a direct influence on the SAR images. Hence a scheme of frequency synthesizer to achieve high performance MMW LFMCW waveform is proposed. This synthesizer driven by a DDS array can adaptive suppress the spurious level without degradation of excellent frequency linearity and fast switching speed.

  9. Design of Unstructured Adaptive (UA) NAS Parallel Benchmark Featuring Irregular, Dynamic Memory Accesses

    NASA Technical Reports Server (NTRS)

    Feng, Hui-Yu; VanderWijngaart, Rob; Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    We describe the design of a new method for the measurement of the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. The method involves the solution of a stylized heat transfer problem on an unstructured, adaptive grid. A Spectral Element Method (SEM) with an adaptive, nonconforming mesh is selected to discretize the transport equation. The relatively high order of the SEM lowers the fraction of wall clock time spent on inter-processor communication, which eases the load balancing task and allows us to concentrate on the memory accesses. The benchmark is designed to be three-dimensional. Parallelization and load balance issues of a reference implementation will be described in detail in future reports.

  10. Neural Network Control-Based Adaptive Learning Design for Nonlinear Systems With Full-State Constraints.

    PubMed

    Liu, Yan-Jun; Li, Jing; Tong, Shaocheng; Chen, C L Philip

    2016-07-01

    In order to stabilize a class of uncertain nonlinear strict-feedback systems with full-state constraints, an adaptive neural network control method is investigated in this paper. The state constraints are frequently emerged in the real-life plants and how to avoid the violation of state constraints is an important task. By introducing a barrier Lyapunov function (BLF) to every step in a backstepping procedure, a novel adaptive backstepping design is well developed to ensure that the full-state constraints are not violated. At the same time, one remarkable feature is that the minimal learning parameters are employed in BLF backstepping design. By making use of Lyapunov analysis, we can prove that all the signals in the closed-loop system are semiglobal uniformly ultimately bounded and the output is well driven to follow the desired output. Finally, a simulation is given to verify the effectiveness of the method.

  11. Adaptive sliding mode control design for a class of uncertain singularly perturbed nonlinear systems

    NASA Astrophysics Data System (ADS)

    Lin, Kuo-Jung

    2014-02-01

    This paper addresses adaptive sliding mode control (ASMC) of uncertain singularly perturbed nonlinear (USPN) systems with guaranteed H∞ control performance. First, we use Takagi-Sugeno (T-S) fuzzy model to construct the USPN systems. Then, the sliding surface can be determined via linear matrix inequality (LMI) design procedure. Second, we propose neural network (NN)-based ASMC design to stabilise the USPN systems. The proposed methods are based on the Lyapunov stability theorem. The adaptive law can reduce the effect of uncertainty. The proposed NN-based ASMC will stabilise the USPN systems for all ɛ ∈ (0, ɛ*]. Simulation result reveals that the proposed NN-based ASMC scheme has better convergence time compared with the fuzzy control scheme (Li, T.-H.S., & Lin, K.J. (2004). Stabilization of singularly perturbed fuzzy systems, IEEE Transactions on Fuzzy Systems, 12, 579-595.).

  12. Design of an effective energy receiving adapter for microwave wireless power transmission application

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    In this paper, we demonstrate the viability of an energy receiving adapter in a 8×8 array form with high power reception efficiency with the resonator of artificial electromagnetic absorber being used as the element. Unlike the conventional reported rectifying antenna resonators, both the size of the element and the separations between the elements are electrically small in our design. The energy collecting process is explained with an equivalent circuit model, and a RF combining network is designed to combine the captured AC power from each element to one main terminal for AC-to-DC conversion. The energy receiving adapter yields a total reception efficiency of 67% (including the wave capture efficiency of 86% and the AC-to-DC conversion efficiency of 78%), which is quite promising for microwave wireless power transmission.

  13. Optimization of magnetic neurostimulation waveforms for minimum power loss.

    PubMed

    Goetz, S M; Truong, N C; Gerhofer, M G; Peterchev, A V; Herzog, H-G; Weyh, T

    2012-01-01

    Magnetic stimulation is a key tool in experimental brain research and several clinical applications. Whereas coil designs and the spatial field properties have been intensively studied in the literature, the temporal dynamics of the field has received little attention. The available pulse shapes are typically determined by the relatively limited capabilities of commercial stimulation devices instead of efficiency or optimality. Furthermore, magnetic stimulation is relatively inefficient with respect to the required energy compared to other neurostimulation techniques. We therefore analyze and optimize the waveform dynamics with a nonlinear model of a mammalian motor axon for the first time, without any pre-definition of waveform candidates. We implemented an unbiased and stable numerical algorithm using variational calculus in combination with a global optimization method. This approach yields very stable results with comprehensible characteristic properties, such as a first phase which reduces ohmic losses in the subsequent pulse phase. We compare the energy loss of these optimal waveforms with the waveforms generated by existing magnetic stimulation devices.

  14. A compact, multichannel, and low noise arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Govorkov, S.; Ivanov, B. I.; Il'ichev, E.; Meyer, H.-G.

    2014-05-01

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  15. A compact, multichannel, and low noise arbitrary waveform generator.

    PubMed

    Govorkov, S; Ivanov, B I; Il'ichev, E; Meyer, H-G

    2014-05-01

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  16. A compact, multichannel, and low noise arbitrary waveform generator

    SciTech Connect

    Govorkov, S.; Ivanov, B. I.; Il'ichev, E.; Meyer, H.-G.

    2014-05-15

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  17. RARtool: A MATLAB Software Package for Designing Response-Adaptive Randomized Clinical Trials with Time-to-Event Outcomes.

    PubMed

    Ryeznik, Yevgen; Sverdlov, Oleksandr; Wong, Weng Kee

    2015-08-01

    Response-adaptive randomization designs are becoming increasingly popular in clinical trial practice. In this paper, we present RARtool, a user interface software developed in MATLAB for designing response-adaptive randomized comparative clinical trials with censored time-to-event outcomes. The RARtool software can compute different types of optimal treatment allocation designs, and it can simulate response-adaptive randomization procedures targeting selected optimal allocations. Through simulations, an investigator can assess design characteristics under a variety of experimental scenarios and select the best procedure for practical implementation. We illustrate the utility of our RARtool software by redesigning a survival trial from the literature.

  18. Stakeholder Collaboration in Air Force Acquisition: Adaptive Design Using System Representations

    DTIC Science & Technology

    2003-06-01

    that CAS principles are important considerations to understand inter-organizational interactions and adaptability. The research has also expanded...fielded systems. Therefore, the design phase is a unique time when it is possible to visualize and interact with the system when changes are still...affordable. 12 Acknowledgements I want to recognize a number of individuals who helped make this dissertation possible . I start with my committee

  19. An adaptive-control switching buck regulator - Implementation, analysis, and design

    NASA Technical Reports Server (NTRS)

    Lee, F. C.; Yu, Y.

    1980-01-01

    Describing-function techniques and averaging methods have been employed to characterize a multiloop switching buck regulator by three functional blocks: power stage, analog signal processor, and pulse modulator. The model is employed to explore possible forms of pole-zero cancellation and the adaptive nature of the control to filter parameter changes. Analysis-based design guidelines are provided including a suggested additional RC-compensation loop to optimize regulator performances such as stability, audiosusceptibility, output impedance, and load transient response.

  20. A varying-stage adaptive phase II/III clinical trial design.

    PubMed

    Dong, Gaohong

    2014-04-15

    Currently, adaptive phase II/III clinical trials are typically carried out with a strict two-stage design. The first stage is a learning stage called phase II, and the second stage is a confirmatory stage called phase III. Following phase II analysis, inefficacious or harmful dose arms are dropped, then one or two promising dose arms are selected for the second stage. However, there are often situations in which researchers are in dilemma to make 'go or no-go' decision and/or to select 'best' dose arm(s), as data from the first stage may not provide sufficient information for their decision making. In this case, it is challenging to follow a strict two-stage plan. Therefore, we propose a varying-stage adaptive phase II/III clinical trial design, in which we consider whether there is a need to have an intermediate stage to obtain more data, so that a more informative decision could be made. Hence, the number of further investigational stages in our design is determined on the basis of data accumulated to the interim analysis. With respect to adaptations, we consider dropping dose arm(s), switching another plausible endpoint as the primary study endpoint, re-estimating sample size, and early stopping for futility. We use an adaptive combination test to perform final analyses. By applying closed testing procedure, we control family-wise type I error rate at the nominal level of α in the strong sense. We delineate other essential design considerations including the threshold parameters and the proportion of alpha allocated in the two-stage versus three-stage setting.

  1. Building Adaptive Game-Based Learning Resources: The Integration of IMS Learning Design and

    ERIC Educational Resources Information Center

    Burgos, Daniel; Moreno-Ger, Pablo; Sierra, Jose Luis; Fernandez-Manjon, Baltasar; Specht, Marcus; Koper, Rob

    2008-01-01

    IMS Learning Design (IMS-LD) is a specification to create units of learning (UoLs), which express a certain pedagogical model or strategy (e.g., adaptive learning with games). However, the authoring process of a UoL remains difficult because of the lack of high-level authoring tools for IMS-LD, even more so when the focus is on specific topics,…

  2. 3D design and electric simulation of a silicon drift detector using a spiral biasing adapter

    NASA Astrophysics Data System (ADS)

    Li, Yu-yun; Xiong, Bo; Li, Zheng

    2016-09-01

    The detector system of combining a spiral biasing adapter (SBA) with a silicon drift detector (SBA-SDD) is largely different from the traditional silicon drift detector (SDD), including the spiral SDD. It has a spiral biasing adapter of the same design as a traditional spiral SDD and an SDD with concentric rings having the same radius. Compared with the traditional spiral SDD, the SBA-SDD separates the spiral's functions of biasing adapter and the p-n junction definition. In this paper, the SBA-SDD is simulated using a Sentaurus TCAD tool, which is a full 3D device simulation tool. The simulated electric characteristics include electric potential, electric field, electron concentration, and single event effect. Because of the special design of the SBA-SDD, the SBA can generate an optimum drift electric field in the SDD, comparable with the conventional spiral SDD, while the SDD can be designed with concentric rings to reduce surface area. Also the current and heat generated in the SBA are separated from the SDD. To study the single event response, we simulated the induced current caused by incident heavy ions (20 and 50 μm penetration length) with different linear energy transfer (LET). The SBA-SDD can be used just like a conventional SDD, such as X-ray detector for energy spectroscopy and imaging, etc.

  3. Robust Brain-Machine Interface Design Using Optimal Feedback Control Modeling and Adaptive Point Process Filtering

    PubMed Central

    Carmena, Jose M.

    2016-01-01

    Much progress has been made in brain-machine interfaces (BMI) using decoders such as Kalman filters and finding their parameters with closed-loop decoder adaptation (CLDA). However, current decoders do not model the spikes directly, and hence may limit the processing time-scale of BMI control and adaptation. Moreover, while specialized CLDA techniques for intention estimation and assisted training exist, a unified and systematic CLDA framework that generalizes across different setups is lacking. Here we develop a novel closed-loop BMI training architecture that allows for processing, control, and adaptation using spike events, enables robust control and extends to various tasks. Moreover, we develop a unified control-theoretic CLDA framework within which intention estimation, assisted training, and adaptation are performed. The architecture incorporates an infinite-horizon optimal feedback-control (OFC) model of the brain’s behavior in closed-loop BMI control, and a point process model of spikes. The OFC model infers the user’s motor intention during CLDA—a process termed intention estimation. OFC is also used to design an autonomous and dynamic assisted training technique. The point process model allows for neural processing, control and decoder adaptation with every spike event and at a faster time-scale than current decoders; it also enables dynamic spike-event-based parameter adaptation unlike current CLDA methods that use batch-based adaptation on much slower adaptation time-scales. We conducted closed-loop experiments in a non-human primate over tens of days to dissociate the effects of these novel CLDA components. The OFC intention estimation improved BMI performance compared with current intention estimation techniques. OFC assisted training allowed the subject to consistently achieve proficient control. Spike-event-based adaptation resulted in faster and more consistent performance convergence compared with batch-based methods, and was robust to

  4. Robust Brain-Machine Interface Design Using Optimal Feedback Control Modeling and Adaptive Point Process Filtering.

    PubMed

    Shanechi, Maryam M; Orsborn, Amy L; Carmena, Jose M

    2016-04-01

    Much progress has been made in brain-machine interfaces (BMI) using decoders such as Kalman filters and finding their parameters with closed-loop decoder adaptation (CLDA). However, current decoders do not model the spikes directly, and hence may limit the processing time-scale of BMI control and adaptation. Moreover, while specialized CLDA techniques for intention estimation and assisted training exist, a unified and systematic CLDA framework that generalizes across different setups is lacking. Here we develop a novel closed-loop BMI training architecture that allows for processing, control, and adaptation using spike events, enables robust control and extends to various tasks. Moreover, we develop a unified control-theoretic CLDA framework within which intention estimation, assisted training, and adaptation are performed. The architecture incorporates an infinite-horizon optimal feedback-control (OFC) model of the brain's behavior in closed-loop BMI control, and a point process model of spikes. The OFC model infers the user's motor intention during CLDA-a process termed intention estimation. OFC is also used to design an autonomous and dynamic assisted training technique. The point process model allows for neural processing, control and decoder adaptation with every spike event and at a faster time-scale than current decoders; it also enables dynamic spike-event-based parameter adaptation unlike current CLDA methods that use batch-based adaptation on much slower adaptation time-scales. We conducted closed-loop experiments in a non-human primate over tens of days to dissociate the effects of these novel CLDA components. The OFC intention estimation improved BMI performance compared with current intention estimation techniques. OFC assisted training allowed the subject to consistently achieve proficient control. Spike-event-based adaptation resulted in faster and more consistent performance convergence compared with batch-based methods, and was robust to parameter

  5. Anti-windup adaptive PID control design for a class of uncertain chaotic systems with input saturation.

    PubMed

    Tahoun, A H

    2017-01-01

    In this paper, the stabilization problem of actuators saturation in uncertain chaotic systems is investigated via an adaptive PID control method. The PID control parameters are auto-tuned adaptively via adaptive control laws. A multi-level augmented error is designed to account for the extra terms appearing due to the use of PID and saturation. The proposed control technique uses both the state-feedback and the output-feedback methodologies. Based on Lyapunov׳s stability theory, new anti-windup adaptive controllers are proposed. Demonstrative examples with MATLAB simulations are studied. The simulation results show the efficiency of the proposed adaptive PID controllers.

  6. Optical arbitrary waveform characterization using linear spectrograms.

    PubMed

    Jiang, Zhi; Leaird, Daniel E; Long, Christopher M; Boppart, Stephen A; Weiner, Andrew M

    2010-08-01

    We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms.

  7. Electron microscopy of electromagnetic waveforms

    NASA Astrophysics Data System (ADS)

    Ryabov, A.; Baum, P.

    2016-07-01

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample’s oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available.

  8. The Applied Behavior Analysis Research Paradigm and Single-Subject Designs in Adapted Physical Activity Research.

    PubMed

    Haegele, Justin A; Hodge, Samuel Russell

    2015-10-01

    There are basic philosophical and paradigmatic assumptions that guide scholarly research endeavors, including the methods used and the types of questions asked. Through this article, kinesiology faculty and students with interests in adapted physical activity are encouraged to understand the basic assumptions of applied behavior analysis (ABA) methodology for conducting, analyzing, and presenting research of high quality in this paradigm. The purposes of this viewpoint paper are to present information fundamental to understanding the assumptions undergirding research methodology in ABA, describe key aspects of single-subject research designs, and discuss common research designs and data-analysis strategies used in single-subject studies.

  9. Design of acoustic metamaterials using the covariance matrix adaptation evolutionary strategy

    NASA Astrophysics Data System (ADS)

    Huang, Bei; Cheng, Qiang; Song, Gang Yong; Cui, Tie Jun

    2017-03-01

    Acoustic metamaterials can manipulate sound waves in surprising ways, including the focusing, cloaking, and extraordinary transmitting of sound waves. With the increasing requirements for acoustic metamaterials with extreme parameters, we propose the design of acoustic meta-atoms with a large refraction index using the covariance matrix adaptation evolutionary optimization strategy. To validate the procedure, we propose an optimized metamaterial to construct an acoustic deflection lens. The full-wave simulation results are consistent with the theoretical predictions, showing the efficacy and accuracy of the proposed method, and indicating that the optimization algorithm is a powerful tool for designing meta-atoms with excellent applications.

  10. Object-oriented software design for the Mt. Wilson 100-inch Hooker telescope adaptive optics system

    NASA Astrophysics Data System (ADS)

    Schneider, Thomas G.

    2000-06-01

    The object oriented software design paradigm has been instrumented in the development of the Adoptics software used in the Hooker telescope's ADOPT adaptive optics system. The software runs on a Pentium-class PC host and eight DSP processors connected to the host's motherboard bus. C++ classes were created to implement most of the host software's functionality, with the object oriented features of inheritance, encapsulation and abstraction being the most useful. Careful class design at the inception of the project allowed for the rapid addition of features without comprising the integrity of the software. Base class implementations include the DSP system, real-time graphical displays and opto-mechanical actuator control.

  11. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2006-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital one's or zero's. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental physical laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  12. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2004-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital ONEs or ZEROs. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental natural laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  13. Biomarker-Guided Non-Adaptive Trial Designs in Phase II and Phase III: A Methodological Review

    PubMed Central

    Antoniou, Miranta; Kolamunnage-Dona, Ruwanthi; Jorgensen, Andrea L.

    2017-01-01

    Biomarker-guided treatment is a rapidly developing area of medicine, where treatment choice is personalised according to one or more of an individual’s biomarker measurements. A number of biomarker-guided trial designs have been proposed in the past decade, including both adaptive and non-adaptive trial designs which test the effectiveness of a biomarker-guided approach to treatment with the aim of improving patient health. A better understanding of them is needed as challenges occur both in terms of trial design and analysis. We have undertaken a comprehensive literature review based on an in-depth search strategy with a view to providing the research community with clarity in definition, methodology and terminology of the various biomarker-guided trial designs (both adaptive and non-adaptive designs) from a total of 211 included papers. In the present paper, we focus on non-adaptive biomarker-guided trial designs for which we have identified five distinct main types mentioned in 100 papers. We have graphically displayed each non-adaptive trial design and provided an in-depth overview of their key characteristics. Substantial variability has been observed in terms of how trial designs are described and particularly in the terminology used by different authors. Our comprehensive review provides guidance for those designing biomarker-guided trials. PMID:28125057

  14. Modeling Gravitational Radiation Waveforms from Black Hole Mergers

    NASA Technical Reports Server (NTRS)

    Baker, J. G.; Centrelia, J. M.; Choi, D.; Koppitz, M.; VanMeter, J.

    2006-01-01

    Gravitational radiation from merging binary black hole systems is anticipated as a key source for gravitational wave observations. Ground-based instruments, such as the Laser Interferometer Gravitational-wave Observatory (LIGO) may observe mergers of stellar-scale black holes, while the space-based Laser Interferometer Space Antenna (LISA) observatory will be sensitive to mergers of massive galactic-center black holes over a broad range of mass scales. These cataclysmic events may emit an enormous amount of energy in a brief time. Gravitational waves from comparable mass mergers carry away a few percent of the system's mass-energy in just a few wave cycles, with peak gravitational wave luminosities on the order of 10^23 L_Sun. Optimal analysis and interpretation of merger observation data will depend on developing a detailed understanding, based on general relativistic modeling, of the radiation waveforms. We discuss recent progress in modeling radiation from equal mass mergers using numerical simulations of Einstein's gravitational field equations, known as numerical relativity. Our simulations utilize Adaptive Mesh Refinement (AMR) to allow high-resolution near the black holes while simultaneously keeping the outer boundary of the computational domain far from the black holes, and making it possible to read out gravitational radiation waveforms in the weak-field wave zone. We discuss the results from simulations beginning with the black holes orbiting near the system's innermost stable orbit, comparing the recent simulations with earlier "Lazarus" waveform estimates based on an approximate hybrid numerical/perturbative technique.

  15. Acquisition of L2 Japanese Geminates: Training with Waveform Displays

    ERIC Educational Resources Information Center

    Motohashi-Saigo, Miki; Hardison, Debra M.

    2009-01-01

    The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV) and auditory-only (A-only) Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two…

  16. An Adaptive Damping Network Designed for Strapdown Fiber Optic Gyrocompass System for Ships

    PubMed Central

    Sun, Jin; Xu, Xiaosu; Liu, Yiting; Zhang, Tao; Li, Yao; Tong, Jinwu

    2017-01-01

    The strapdown fiber optic gyrocompass (strapdown FOGC) system for ships primarily works on external horizontal damping and undamping statuses. When there are large sea condition changes, the system will switch frequently between the external horizontal damping status and the undamping status. This means that the system is always in an adjustment status and influences the dynamic accuracy of the system. Aiming at the limitations of the conventional damping method, a new design idea is proposed, where the adaptive control method is used to design the horizontal damping network of the strapdown FOGC system. According to the size of acceleration, the parameters of the damping network are changed to make the system error caused by the ship’s maneuvering to a minimum. Furthermore, the jump in damping coefficient was transformed into gradual change to make a smooth system status switch. The adaptive damping network was applied for strapdown FOGC under the static and dynamic condition, and its performance was compared with the conventional damping, and undamping means. Experimental results showed that the adaptive damping network was effective in improving the dynamic performance of the strapdown FOGC. PMID:28257100

  17. Design of adaptive two-stage double-arm clinical trials for dichotomous variables.

    PubMed

    Jiang, Zhiwei; Xue, Fubo; Li, Chanjuan; Wang, Ling; Cai, Hongwei; Zhang, Chunmao; Xia, Jielai

    2010-05-01

    It is well known that flexibility is one of the major advantages of an adaptive two-stage design, and the intended adaptation should be as preplanned as possible to maintain the integrity of the clinical trial. The design of adaptive two-stage double-arm clinical trials for dichotomous variables was proposed by simulation and forecasting procedure at the planning stage. To further ensure the integrity of the clinical trial, the sample size scheme for each scenario, which was supposed to be based on the first stage, was provided in the protocol by Monte Carlo simulation. In addition, the study parameters were determined by comparing the assessment indexes such as total sample size, expected sample size and the test power at the first stage. Furthermore, Fisher's combination test and pooled data analysis were considered and compared through the simulation. The latter, which has the larger overall power and the better overall type I error control, with the same sample size was adopted for further simulation and statistical analysis in the clinical trial.

  18. A new adaptive videogame for training attention and executive functions: design principles and initial validation.

    PubMed

    Montani, Veronica; De Filippo De Grazia, Michele; Zorzi, Marco

    2014-01-01

    A growing body of evidence suggests that action videogames could enhance a variety of cognitive skills and more specifically attention skills. The aim of this study was to develop a novel adaptive videogame to support the rehabilitation of the most common consequences of traumatic brain injury (TBI), that is the impairment of attention and executive functions. TBI patients can be affected by psychomotor slowness and by difficulties in dealing with distraction, maintain a cognitive set for a long time, processing different simultaneously presented stimuli, and planning purposeful behavior. Accordingly, we designed a videogame that was specifically conceived to activate those functions. Playing involves visuospatial planning and selective attention, active maintenance of the cognitive set representing the goal, and error monitoring. Moreover, different game trials require to alternate between two tasks (i.e., task switching) or to perform the two tasks simultaneously (i.e., divided attention/dual-tasking). The videogame is controlled by a multidimensional adaptive algorithm that calibrates task difficulty on-line based on a model of user performance that is updated on a trial-by-trial basis. We report simulations of user performance designed to test the adaptive game as well as a validation study with healthy participants engaged in a training protocol. The results confirmed the involvement of the cognitive abilities that the game is supposed to enhance and suggested that training improved attentional control during play.

  19. Single and Multiresponse Adaptive Design of Experiments with Application to Design Optimization of Novel Heat Exchangers

    DTIC Science & Technology

    2009-01-01

    performance evaluation method for air- cooled heat exchangers in which conventional 3D Computational Fluid Dynamics (CFD) simulation is replaced with a 2D...parts to this research thrust. First, is a new multi-level performance evaluation method for air- cooled heat exchangers in which conventional 3D...performance of a novel air- cooled heat exchanger such as tube-fin or microchannels . The novel aspect generally refers to a new fin design or a tube

  20. Waveform-Agile Tracking In Heavy Sea Clutter

    DTIC Science & Technology

    2007-01-01

    Waveform-Agile Tracking In Heavy Sea Clutter Sandeep P. Sira , Antonia Papandreou-Suppappola, Darryl Morrell†, and Douglas Cochran SenSIP Center...to a non-adaptive system. The paper is organized as follows. In Section II, we describe the models for the target dynamics, clutter, and observations ...dependence on zs[n]. C. Observations Model At the end of Sub-dwell 2 of the kth dwell, the measurement provided to the tracker is Yk = [yTn̂0−nv

  1. Designing Adaptive Low-Dissipative High Order Schemes for Long-Time Integrations. Chapter 1

    NASA Technical Reports Server (NTRS)

    Yee, Helen C.; Sjoegreen, B.; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    A general framework for the design of adaptive low-dissipative high order schemes is presented. It encompasses a rather complete treatment of the numerical approach based on four integrated design criteria: (1) For stability considerations, condition the governing equations before the application of the appropriate numerical scheme whenever it is possible; (2) For consistency, compatible schemes that possess stability properties, including physical and numerical boundary condition treatments, similar to those of the discrete analogue of the continuum are preferred; (3) For the minimization of numerical dissipation contamination, efficient and adaptive numerical dissipation control to further improve nonlinear stability and accuracy should be used; and (4) For practical considerations, the numerical approach should be efficient and applicable to general geometries, and an efficient and reliable dynamic grid adaptation should be used if necessary. These design criteria are, in general, very useful to a wide spectrum of flow simulations. However, the demand on the overall numerical approach for nonlinear stability and accuracy is much more stringent for long-time integration of complex multiscale viscous shock/shear/turbulence/acoustics interactions and numerical combustion. Robust classical numerical methods for less complex flow physics are not suitable or practical for such applications. The present approach is designed expressly to address such flow problems, especially unsteady flows. The minimization of employing very fine grids to overcome the production of spurious numerical solutions and/or instability due to under-resolved grids is also sought. The incremental studies to illustrate the performance of the approach are summarized. Extensive testing and full implementation of the approach is forthcoming. The results shown so far are very encouraging.

  2. Design of sewage treatment system by applying fuzzy adaptive PID controller

    NASA Astrophysics Data System (ADS)

    Jin, Liang-Ping; Li, Hong-Chan

    2013-03-01

    In the sewage treatment system, the dissolved oxygen concentration control, due to its nonlinear, time-varying, large time delay and uncertainty, is difficult to establish the exact mathematical model. While the conventional PID controller only works with good linear not far from its operating point, it is difficult to realize the system control when the operating point far off. In order to solve the above problems, the paper proposed a method which combine fuzzy control with PID methods and designed a fuzzy adaptive PID controller based on S7-300 PLC .It employs fuzzy inference method to achieve the online tuning for PID parameters. The control algorithm by simulation and practical application show that the system has stronger robustness and better adaptability.

  3. Just-in-time adaptive classifiers-part II: designing the classifier.

    PubMed

    Alippi, Cesare; Roveri, Manuel

    2008-12-01

    Aging effects, environmental changes, thermal drifts, and soft and hard faults affect physical systems by changing their nature and behavior over time. To cope with a process evolution adaptive solutions must be envisaged to track its dynamics; in this direction, adaptive classifiers are generally designed by assuming the stationary hypothesis for the process generating the data with very few results addressing nonstationary environments. This paper proposes a methodology based on k-nearest neighbor (NN) classifiers for designing adaptive classification systems able to react to changing conditions just-in-time (JIT), i.e., exactly when it is needed. k-NN classifiers have been selected for their computational-free training phase, the possibility to easily estimate the model complexity k and keep under control the computational complexity of the classifier through suitable data reduction mechanisms. A JIT classifier requires a temporal detection of a (possible) process deviation (aspect tackled in a companion paper) followed by an adaptive management of the knowledge base (KB) of the classifier to cope with the process change. The novelty of the proposed approach resides in the general framework supporting the real-time update of the KB of the classification system in response to novel information coming from the process both in stationary conditions (accuracy improvement) and in nonstationary ones (process tracking) and in providing a suitable estimate of k. It is shown that the classification system grants consistency once the change targets the process generating the data in a new stationary state, as it is the case in many real applications.

  4. Design and Flight Tests of an Adaptive Control System Employing Normal-Acceleration Command

    NASA Technical Reports Server (NTRS)

    McNeill, Water E.; McLean, John D.; Hegarty, Daniel M.; Heinle, Donovan R.

    1961-01-01

    An adaptive control system employing normal-acceleration command has been designed with the aid of an analog computer and has been flight tested. The design of the system was based on the concept of using a mathematical model in combination with a high gain and a limiter. The study was undertaken to investigate the application of a system of this type to the task of maintaining nearly constant dynamic longitudinal response of a piloted airplane over the flight envelope without relying on air data measurements for gain adjustment. The range of flight conditions investigated was between Mach numbers of 0.36 and 1.15 and altitudes of 10,000 and 40,000 feet. The final adaptive system configuration was derived from analog computer tests, in which the physical airplane control system and much of the control circuitry were included in the loop. The method employed to generate the feedback signals resulted in a model whose characteristics varied somewhat with changes in flight condition. Flight results showed that the system limited the variation in longitudinal natural frequency of the adaptive airplane to about half that of the basic airplane and that, for the subsonic cases, the damping ratio was maintained between 0.56 and 0.69. The system also automatically compensated for the transonic trim change. Objectionable features of the system were an exaggerated sensitivity of pitch attitude to gust disturbances, abnormally large pitch attitude response for a given pilot input at low speeds, and an initial delay in normal-acceleration response to pilot control at all flight conditions. The adaptive system chatter of +/-0.05 to +/-0.10 of elevon at about 9 cycles per second (resulting in a maximum airplane normal-acceleration response of from +/-0.025 g to +/- 0.035 g) was considered by the pilots to be mildly objectionable but tolerable.

  5. Designing Adaptive, Diagnostic Math Assessments for Individuals with and without Visual Disabilities. Research Report. ETS RR-06-01

    ERIC Educational Resources Information Center

    Shute, Valerie J.; Graf, Edith Aurora; Hansen, Eric G.

    2006-01-01

    This report summarizes the design and development of an adaptive e-learning prototype for middle school mathematics for use with both sighted and visually disabled students. Adaptation refers to the system's ability to adjust itself to suit particular characteristics of the learner. The main parts of the report describe the system's theoretical…

  6. Designing a meta-level architecture in Java for adaptive parallelism by mobile software agents

    NASA Astrophysics Data System (ADS)

    Dominic, Stephen Victor

    Adaptive parallelism refers to a parallel computation that runs on a pool of processors that may join or withdraw from a running computation. In this dissertation, a functional system of agents and agent behaviors for adaptive parallelism is developed. Software agents have the properties of robustness and have capacity for fault-tolerance. Adaptation and fault-tolerance emerge from the interaction of self-directed autonomous software agents for a parallel computation application. The multi-agent system can be considered an object-oriented system with a higher-level architectural component, i.e., a meta level for agent behavior. The meta-level object architecture is based on patterns of behavior and communication for mobile agents, which are developed to support cooperative problem solving in a distributed-heterogeneous computing environment. Although parallel processing is a suggested application domain for mobile agents implemented in the Java language, the development of robust agent behaviors implemented in an efficient manner is an active research area. Performance characteristics for three versions of a pattern recognition problem are used to demonstrate a linear speed-up with efficiency that is compared to research using a traditional client-server protocol in the C language. The best ideas from existing approaches to adaptive parallelism are used to create a single general-purpose paradigm that overcomes problems associated with nodefailure, the use of a single-centralized or shared resource, requirements for clients to actively join a computation, and a variety of other limitations that are associated with existing systems. The multi-agent system, and experiments, show how adaptation and parallelism can be exploited by a meta-architecture for a distributed-scientific application that is of particular interest to design of signal-processing ground stations. To a large extent the framework separates concern for algorithmic design from concern for where and

  7. Flow pumping system for physiological waveforms.

    PubMed

    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.

  8. Doppler-Offset Waveforms for MIMO Radar

    DTIC Science & Technology

    2010-01-01

    Division Multiple Access, or FDMA . In the MIMO radar literature, the term FDMA is used, generically, to refer to sets of waveforms occupying different...frequencies at the same time. Mathematically, the lit" FDMA waveform can be written as: S" (I) = s (I) ej 2K I.’ 0 5, 1 5, T . for /I = I, ... ,N...noise) whenever i i’ j . Page 3 of 13 Pages On transmit, FDMA MIMO radars emit all N, frequency offset waveforms simultaneously. Then, each of the N

  9. Elliptic waveforms for inspiralling compact binaries

    NASA Astrophysics Data System (ADS)

    Mikóczi, Balázs

    2010-03-01

    The inspiral of supermassive black hole binary systems with high orbital eccentricity are the most promising sources for the gravitational wave observatories. The importance of elliptic gravitational waveforms in various physical scenarios has been emphasized by several authors (Wahlquist 1987, Moreno-Garrido, Buitrago and Mediavilla 1994, Martel and Poisson 1999). Taking into account the eccentricity of the orbit in the total waveform improves the parameter estimation for these sources, as it is shown by the construction and analyzation of the Fisher information matrix. In our work we use the Fourier-Bessel analysis of the Kepler motion and the stationary phase approximation of time-depend waveforms.

  10. [Study of sharing platform of web-based enhanced extracorporeal counterpulsation hemodynamic waveform data].

    PubMed

    Huang, Mingbo; Hu, Ding; Yu, Donglan; Zheng, Zhensheng; Wang, Kuijian

    2011-12-01

    Enhanced extracorporeal counterpulsation (EECP) information consists of both text and hemodynamic waveform data. At present EECP text information has been successfully managed through Web browser, while the management and sharing of hemodynamic waveform data through Internet has not been solved yet. In order to manage EECP information completely, based on the in-depth analysis of EECP hemodynamic waveform file of digital imaging and communications in medicine (DICOM) format and its disadvantages in Internet sharing, we proposed the use of the extensible markup language (XML), which is currently the Internet popular data exchange standard, as the storage specification for the sharing of EECP waveform data. Then we designed a web-based sharing system of EECP hemodynamic waveform data via ASP. NET 2.0 platform. Meanwhile, we specifically introduced the four main system function modules and their implement methods, including DICOM to XML conversion module, EECP waveform data management module, retrieval and display of EECP waveform module and the security mechanism of the system.

  11. CONDITIONING AND PROTECTION CIRCUITRY FOR EXTERNAL MODULATION OF A PREPROGRAMMED GYROTRON CATHODE VOLTAGE COMMAND WAVEFORM

    SciTech Connect

    PONCE,D; FERRON,J.R; LEGG,R.A

    2003-10-01

    OAK-B135 The modulating voltages applied to the DIII-D gyrotrons are controlled by reference signals which are synthesized by arbitrary waveform generators.These generators allow ECH operators to pre-program reference waveforms consisting of ramps, flat tops, and various modulation shapes. This capability is independent of the DIII-D central timing and waveform facilities, which provides the ECH operators operational flexibility. The waveform generators include an amplitude modulation input, providing a means to control the pre-programmed waveform externally. This input is being used to allow the DIII-D plasma control system (PCS) to control gyrotron power in response top selected feedback signals. As the PCS control signal could potentially modulate the gyrotrons beyond operational limits or otherwise in a manner leading to recalcitrant rf generation, the control signal is conditioned so that its effect upon the ECH pre-programmed reference waveform is limited by conditions set by the ECH operators. The design of the circuitry which restricts the range over which the PCS control signal may modulate the reference waveform will be discussed. Test and DIII-D experimental results demonstrating the utility and effectiveness of gyrotron power modulated by the PCS will be presented.

  12. Wavefield Compression for Full-Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Boehm, Christian; Fichtner, Andreas; de la Puente, Josep; Hanzich, Mauricio

    2015-04-01

    We present compression techniques tailored to iterative nonlinear minimization methods that significantly reduce the memory requirements to store the forward wavefield for the computation of sensitivity kernels. Full-waveform inversion on 3d data sets requires massive computing and memory capabilities. Adjoint techniques offer a powerful tool to compute the first and second derivatives. However, due to the asynchronous nature of forward and adjoint simulations, a severe bottleneck is introduced by the necessity to access both wavefields simultaneously when computing sensitivity kernels. There exist two opposing strategies to deal with this challenge. On the one hand, conventional approaches save the whole forward wavefield to the disk, which yields a significant I/O overhead and might require several terabytes of storage capacity per seismic event. On the other hand, checkpointing techniques allow to trade an almost arbitrary amount of memory requirements for a - potentially large - number of additional forward simulations. We propose an alternative approach that strikes a balance between memory requirements and the need for additional computations. Here, we aim at compressing the forward wavefield in such a way that (1) the I/O overhead is reduced substantially without the need for additional simulations, (2) the costs for compressing/decompressing the wavefield are negligible, and (3) the approximate derivatives resulting from the compressed forward wavefield do not affect the rate of convergence of a Newton-type minimization method. To this end, we apply an adaptive re-quantization of the displacement field that uses dynamically adjusted floating-point accuracies - i.e., a locally varying number of bits - to store the data. Furthermore, the spectral element functions are adaptively downsampled to a lower polynomial degree. In addition, a sliding-window cubic spline re-interpolates the temporal snapshots to recover a smooth signal. Moreover, a preprocessing step

  13. Predicting Electrocardiogram and Arterial Blood Pressure Waveforms with Different Echo State Network Architectures

    DTIC Science & Technology

    2014-11-01

    networks were trained to predict an individual’s electrocardiogram ( ECG ) and arterial blood pressure (ABP) waveform data, which can potentially help...various ESN architectures for prediction tasks, and establishes the benefits of using ESN architecture designs for predicting ECG and ABP waveforms...alarms into true alarms and false alarms. These authors then developed an algorithm that classified alarms based on both electrocardiogram ( ECG ) and

  14. Viscoacoustic anisotropic full waveform inversion

    NASA Astrophysics Data System (ADS)

    Qu, Yingming; Li, Zhenchun; Huang, Jianping; Li, Jinli

    2017-01-01

    A viscoacoustic vertical transverse isotropic (VTI) quasi-differential wave equation, which takes account for both the viscosity and anisotropy of media, is proposed for wavefield simulation in this study. The finite difference method is used to solve the equations, for which the attenuation terms are solved in the wavenumber domain, and all remaining terms in the time-space domain. To stabilize the adjoint wavefield, robust regularization operators are applied to the wave equation to eliminate the high-frequency component of the numerical noise produced during the backward propagation of the viscoacoustic wavefield. Based on these strategies, we derive the corresponding gradient formula and implement a viscoacoustic VTI full waveform inversion (FWI). Numerical tests verify that our proposed viscoacoustic VTI FWI can produce accurate and stable inversion results for viscoacoustic VTI data sets. In addition, we test our method's sensitivity to velocity, Q, and anisotropic parameters. Our results show that the sensitivity to velocity is much higher than that to Q and anisotropic parameters. As such, our proposed method can produce acceptable inversion results as long as the Q and anisotropic parameters are within predefined thresholds.

  15. Adaptive filter design based on the LMS algorithm for delay elimination in TCR/FC compensators.

    PubMed

    Hooshmand, Rahmat Allah; Torabian Esfahani, Mahdi

    2011-04-01

    Thyristor controlled reactor with fixed capacitor (TCR/FC) compensators have the capability of compensating reactive power and improving power quality phenomena. Delay in the response of such compensators degrades their performance. In this paper, a new method based on adaptive filters (AF) is proposed in order to eliminate delay and increase the response of the TCR compensator. The algorithm designed for the adaptive filters is performed based on the least mean square (LMS) algorithm. In this design, instead of fixed capacitors, band-pass LC filters are used. To evaluate the filter, a TCR/FC compensator was used for nonlinear and time varying loads of electric arc furnaces (EAFs). These loads caused occurrence of power quality phenomena in the supplying system, such as voltage fluctuation and flicker, odd and even harmonics and unbalancing in voltage and current. The above design was implemented in a realistic system model of a steel complex. The simulation results show that applying the proposed control in the TCR/FC compensator efficiently eliminated delay in the response and improved the performance of the compensator in the power system.

  16. Design of adaptive control systems by means of self-adjusting transversal filters

    NASA Technical Reports Server (NTRS)

    Merhav, S. J.

    1986-01-01

    The design of closed-loop adaptive control systems based on nonparametric identification was addressed. Implementation is by self-adjusting Least Mean Square (LMS) transversal filters. The design concept is Model Reference Adaptive Control (MRAC). Major issues are to preserve the linearity of the error equations of each LMS filter, and to prevent estimation bias that is due to process or measurement noise, thus providing necessary conditions for the convergence and stability of the control system. The controlled element is assumed to be asymptotically stable and minimum phase. Because of the nonparametric Finite Impulse Response (FIR) estimates provided by the LMS filters, a-priori information on the plant model is needed only in broad terms. Following a survey of control system configurations and filter design considerations, system implementation is shown here in Single Input Single Output (SISO) format which is readily extendable to multivariable forms. In extensive computer simulation studies the controlled element is represented by a second-order system with widely varying damping, natural frequency, and relative degree.

  17. Formation tracker design of multiple mobile robots with wheel perturbations: adaptive output-feedback approach

    NASA Astrophysics Data System (ADS)

    Yoo, Sung Jin

    2016-11-01

    This paper presents a theoretical design approach for output-feedback formation tracking of multiple mobile robots under wheel perturbations. It is assumed that these perturbations are unknown and the linear and angular velocities of the robots are unmeasurable. First, adaptive state observers for estimating unmeasurable velocities of the robots are developed under the robots' kinematics and dynamics including wheel perturbation effects. Then, we derive a virtual-structure-based formation tracker scheme according to the observer dynamic surface design procedure. The main difficulty of the output-feedback control design is to manage the coupling problems between unmeasurable velocities and unknown wheel perturbation effects. These problems are avoided by using the adaptive technique and the function approximation property based on fuzzy logic systems. From the Lyapunov stability analysis, it is shown that point tracking errors of each robot and synchronisation errors for the desired formation converge to an adjustable neighbourhood of the origin, while all signals in the controlled closed-loop system are semiglobally uniformly ultimately bounded.

  18. Capturing the Active Ingredients of Multicomponent Participatory Organizational Stress Interventions Using an Adapted Study Design.

    PubMed

    Biron, Caroline; Ivers, Hans; Brun, Jean-Pierre

    2016-10-01

    Adapted study designs use process evaluation to incorporate a measure of intervention exposure and create an artificial control and intervention groups. Taking into account exposure levels to interventions combines process and outcome evaluation and strengthens the design of the study when exposure levels cannot be controlled. This study includes longitudinal data (two assessments) with added process measures at time 2 gathered from three complex participatory intervention projects in Canada in a hospital and a university. Structural equation modelling was used to explore the specific working mechanisms of particular interventions on stress outcomes. Results showed that higher exposure to interventions aiming to modify tasks and working conditions reduced demands and improved social support, but not job control, which in turn, reduced psychological distress. Exposure to interventions aiming to improve relationships was not related to psychosocial risks. Most studies cannot explain how interventions produce their effects on outcomes, especially when there are multiple concurrent interventions delivered in several contexts. This study advances knowledge on process evaluation by using an adapted study design to capture the active ingredients of multicomponent interventions and suggesting some mechanisms by which the interventions produce their effects on stress outcomes. It provides an illustration of how to conduct process evaluation and relate exposure levels to observed outcomes. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Adaptive uniform grayscale coded aperture design for high dynamic range compressive spectral imaging

    NASA Astrophysics Data System (ADS)

    Diaz, Nelson; Rueda, Hoover; Arguello, Henry

    2016-05-01

    Imaging spectroscopy is an important area with many applications in surveillance, agriculture and medicine. The disadvantage of conventional spectroscopy techniques is that they collect the whole datacube. In contrast, compressive spectral imaging systems capture snapshot compressive projections, which are the input of reconstruction algorithms to yield the underlying datacube. Common compressive spectral imagers use coded apertures to perform the coded projections. The coded apertures are the key elements in these imagers since they define the sensing matrix of the system. The proper design of the coded aperture entries leads to a good quality in the reconstruction. In addition, the compressive measurements are prone to saturation due to the limited dynamic range of the sensor, hence the design of coded apertures must consider saturation. The saturation errors in compressive measurements are unbounded and compressive sensing recovery algorithms only provide solutions for bounded noise or bounded with high probability. In this paper it is proposed the design of uniform adaptive grayscale coded apertures (UAGCA) to improve the dynamic range of the estimated spectral images by reducing the saturation levels. The saturation is attenuated between snapshots using an adaptive filter which updates the entries of the grayscale coded aperture based on the previous snapshots. The coded apertures are optimized in terms of transmittance and number of grayscale levels. The advantage of the proposed method is the efficient use of the dynamic range of the image sensor. Extensive simulations show improvements in the image reconstruction of the proposed method compared with grayscale coded apertures (UGCA) and adaptive block-unblock coded apertures (ABCA) in up to 10 dB.

  20. Experimental design for the eXtreme Adaptive Optics Planet Imager (XAOPI)

    NASA Astrophysics Data System (ADS)

    Graham, J. R.; Macintosh, B.; Ghez, A.; Kalas, P.; Lloyd, J.; Makidon, R.; Olivier, S.; Patience, J.; Perrin, M.; Poyneer, L.; Severson, S.; Sheinis, A.; Sivaramakrishnan, A.; Troy, M.; Wallace, J.; Wilhelmsen, J.

    2002-12-01

    Direct detection of the light emitted by extra-solar planets represents the next major hurdle in the study of extra-solar planets. The NSF Center for Adaptive Optics is carrying out a design study for a dedicated ultra-high-contrast "extreme" adaptive optics (ExAO) planet imager for an 8-m class telescope. The phase space for such a system is large and trade studies are required to choose optimal values of fundamental parameters such as the telescope diameter and delivered Strehl ratio. To predict the performance of hypothetical AO systems we use models based on Kolmogorov phase screens and Fourier optics. We incorporate additional noise sources such as wavefront measurement error and time-lag errors, and distinguish between the different speckle decorrelation times of each independent error source. To compute a figure of merit for a particular AO system we need to predict the distribution of contrast and angular separation on the sky for planets. There is a large and growing of sample of precision radial velocity detected planets, which can be used to constrain the orbital elements and masses of the underlying population. When combined with the star formation history of the solar neighborhood (or ages of local, young associations), cooling curves and young planet model atmospheres this information can be used to predict how many systems can be detected with different experimental designs. We present results which allow us to evaluate the impact of different AO design choices, observing wavelengths, and target selection. Our technique also allows us to compare and quantify the selection effects associated with precision radial velocity, astrometric and direct imaging searches. This work was supported by the NSF Science and Technology Center for Adaptive Optics, managed by UC Santa Cruz under AST-9876783. Portions of this work was performed under the auspices of the U.S. Department of Energy, under contract No. W-7405-Eng-48.

  1. Adaptive optics real time processing design for the advanced technology solar telescope

    NASA Astrophysics Data System (ADS)

    Richards, Kit

    2012-07-01

    The four meter Advanced Technology Solar Telescope (ATST) adaptive optics (AO) system will require at least twenty-four times the real time processing power as the Dunn Solar Telescope AO system. An FPGA solution for ATST AO real time processing is being pursued instead of the parallel DSP approach used for the Dunn AO76 system. An analysis shows FPGAs will have lower latency and lower hardware cost than an equivalent DSP solution. Interfacing to the proposed high speed camera and the deformable mirror will be simpler and have lower latency than with DSPs. This paper will discuss the current design and progress toward implementing the FPGA solution.

  2. Designing an ecological and adaptable virtual task in the context of executive functions.

    PubMed

    Klinger, Evelyne; Cao, Xue; Douguet, Anne-Sophie; Fuchs, Philippe

    2009-01-01

    Brain damage is a major cause of disability that often leads to deficits in Executive Functions (EF) with dramatic consequences on activities of daily living. While rehabilitation approaches of the dysexecutive syndrome are still limited, Virtual Reality (VR) has shown its potential to propose innovative intervention strategies based on ecologically valid functional tasks. The purpose of this paper is to present the design process of the Therapeutic Virtual Kitchen (TVK) in which ecological and adaptable virtual tasks may be configured by the therapists for patients' assessment and rehabilitation. The outcomes of a preliminary test of feasibility among members of our laboratory and Kerpape Rehabilitation Center are reported and discussed.

  3. Combining decoder design and neural adaptation in brain-machine interfaces.

    PubMed

    Shenoy, Krishna V; Carmena, Jose M

    2014-11-19

    Brain-machine interfaces (BMIs) aim to help people with paralysis by decoding movement-related neural signals into control signals for guiding computer cursors, prosthetic arms, and other assistive devices. Despite compelling laboratory experiments and ongoing FDA pilot clinical trials, system performance, robustness, and generalization remain challenges. We provide a perspective on how two complementary lines of investigation, that have focused on decoder design and neural adaptation largely separately, could be brought together to advance BMIs. This BMI paradigm should also yield new scientific insights into the function and dysfunction of the nervous system.

  4. Controlling a truck with an adaptive critic temporal difference CMAC design

    NASA Technical Reports Server (NTRS)

    Shelton, Robert O.; Peterson, James K.

    1993-01-01

    In this study, CMAC (Cerebellar Model Articulated Controller) neural architectures are shown to be viable for the purposes of real-time learning and control. An adaptive critic temporal difference neurocontrol design has been implemented that learns in real-time how to back up a trailer truck along a fixed straight line trajectory. The truck backer-upper experiment is a standard performance measure in the neural network literature, but previously the training of the controllers was done off-line. With the CMAC neural architectures, it was possible to train the neurocontrollers on-line in real-time on a MS-DOS PC 386.

  5. Update on Optical Design of Adaptive Optics System at Lick Observatory

    SciTech Connect

    Bauman, B J; Gavel, D T; Waltjen, K E; Freeze, G J; Hurd, R L; Gates, E I; Max, C E; Olivier, S S; Pennington, D M

    2001-07-31

    In 1999, we presented our plan to upgrade the adaptive optics (AO) system on the Lick Observatory Shane telescope (3m) from a prototype instrument pressed into field service to a facility instrument. This paper updates the progress of that plan and details several important improvements in the alignment and calibration of the AO bench. The paper also includes a discussion of the problems seen in the original design of the tip/tilt (t/t) sensor used in laser guide star mode, and how these problems were corrected with excellent results.

  6. Reliability Optimization Design for Contact Springs of AC Contactors Based on Adaptive Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Zhao, Sheng; Su, Xiuping; Wu, Ziran; Xu, Chengwen

    The paper illustrates the procedure of reliability optimization modeling for contact springs of AC contactors under nonlinear multi-constraint conditions. The adaptive genetic algorithm (AGA) is utilized to perform reliability optimization on the contact spring parameters of a type of AC contactor. A method that changes crossover and mutation rates at different times in the AGA can effectively avoid premature convergence, and experimental tests are performed after optimization. The experimental result shows that the mass of each optimized spring is reduced by 16.2%, while the reliability increases to 99.9% from 94.5%. The experimental result verifies the correctness and feasibility of this reliability optimization designing method.

  7. Update on optical design of adaptive optics system at Lick Observatory

    NASA Astrophysics Data System (ADS)

    Bauman, Brian J.; Gavel, Donald T.; Waltjen, Kenneth E.; Freeze, Gary J.; Hurd, Randall L.; Gates, Elinor L.; Max, Claire E.; Olivier, Scot S.; Pennington, Deanna M.

    2002-02-01

    In 1999, we presented our plan to upgrade the adaptive optics (AO) system on the Lick Observatory Shane telescope (3m) from a prototype instrument pressed into field service to a facility instrument. This paper updates the progress of that plan and details several important improvements in the alignment and calibration of the AO bench. The paper also includes a discussion of the problems seen in the original design of the tip/tilt (t/t) sensor used in laser guide star mode, and how these problems were corrected with excellent results.

  8. A Novel System for Studying Mechanical Strain Waveform-Dependent Responses in Vascular Smooth Muscle Cells

    PubMed Central

    Lee, Jason; Wong, Mitchell; Smith, Quentin; Baker, Aaron B.

    2013-01-01

    While many studies have examined the effects mechanical forces on vSMCs, there is a limited understanding of how the different arterial strain waveforms that occur in disease and different vascular beds alter vSMC mechanotransduction and phenotype. Here, we present a novel system for applying complex, time-varying strain waveforms to cultured cells and use this system to understand how these waveforms can alter vSMC phenotype and signaling. We have developed a highly adaptable cell culture system that allows the application of mechanical strain to cells in culture and can reproduce the complex dynamic mechanical environment experienced by arterial cells in the body. Using this system, we examined whether the type of applied strain waveform altered phenotypic modulation of vSMCs by mechanical forces. Cells exposed to the brachial waveform had increased phosphorylation of AKT, EGR-1, c-Fos expression and cytoskeletal remodeling in comparison to cells treated with the aortic waveform. In addition, vSMCs exposed to physiological waveforms had adopted a more differentiated phenotype in comparison to those treated with static or sinusoidal cyclic strain, with increased expression of vSMC markers desmin, calponin and SM-22 as well as increased expression of regulatory miRNAs including miR-143, -145 and -221. Taken together, our studies demonstrate the development of a novel system for applying complex, timevarying mechanical forces to cells in culture. In addition, we have shown that physiological strain waveforms have powerful effects on vSMC phenotype. PMID:24096612

  9. Laser-generated focused ultrasound for arbitrary waveforms

    NASA Astrophysics Data System (ADS)

    Chan, Weiwei; Hies, Thomas; Ohl, Claus-Dieter

    2016-10-01

    Transducers for laser generated focused ultrasound can achieve photoacoustic waves with several hundred bars positive pressure in water. Previous designs employed concave glass substrates decorated with catalytically grown carbon nanotubes. Here, we show that arbitrarily shaped surfaces made of polymers and printed with 3d printers allow the generation of waveforms with complex temporal and spatial shape. We first present three different polymer materials together with a simplified deposition technique. This is achieved by painting layers of carbon-nanotube powder and polydimethylsiloxane. Together with a clear resin (Formlabs Photopolymer Clear Resin), pressure amplitudes of 300 bar peak positive were obtained. With the flexibility of polymer substrates, complex waveforms can be generated. This is demonstrated with a stepped surface which launches two waves separated by 0.8 μs. Detailed pressure measurements are supported with shadowgraphy images and simulations of the wave.

  10. Principles underlying the design of "The Number Race", an adaptive computer game for remediation of dyscalculia

    PubMed Central

    Wilson, Anna J; Dehaene, Stanislas; Pinel, Philippe; Revkin, Susannah K; Cohen, Laurent; Cohen, David

    2006-01-01

    Background Adaptive game software has been successful in remediation of dyslexia. Here we describe the cognitive and algorithmic principles underlying the development of similar software for dyscalculia. Our software is based on current understanding of the cerebral representation of number and the hypotheses that dyscalculia is due to a "core deficit" in number sense or in the link between number sense and symbolic number representations. Methods "The Number Race" software trains children on an entertaining numerical comparison task, by presenting problems adapted to the performance level of the individual child. We report full mathematical specifications of the algorithm used, which relies on an internal model of the child's knowledge in a multidimensional "learning space" consisting of three difficulty dimensions: numerical distance, response deadline, and conceptual complexity (from non-symbolic numerosity processing to increasingly complex symbolic operations). Results The performance of the software was evaluated both by mathematical simulations and by five weeks of use by nine children with mathematical learning difficulties. The results indicate that the software adapts well to varying levels of initial knowledge and learning speeds. Feedback from children, parents and teachers was positive. A companion article [1] describes the evolution of number sense and arithmetic scores before and after training. Conclusion The software, open-source and freely available online, is designed for learning disabled children aged 5–8, and may also be useful for general instruction of normal preschool children. The learning algorithm reported is highly general, and may be applied in other domains. PMID:16734905

  11. Design of a Mobile Agent-Based Adaptive Communication Middleware for Federations of Critical Infrastructure Simulations

    NASA Astrophysics Data System (ADS)

    Görbil, Gökçe; Gelenbe, Erol

    The simulation of critical infrastructures (CI) can involve the use of diverse domain specific simulators that run on geographically distant sites. These diverse simulators must then be coordinated to run concurrently in order to evaluate the performance of critical infrastructures which influence each other, especially in emergency or resource-critical situations. We therefore describe the design of an adaptive communication middleware that provides reliable and real-time one-to-one and group communications for federations of CI simulators over a wide-area network (WAN). The proposed middleware is composed of mobile agent-based peer-to-peer (P2P) overlays, called virtual networks (VNets), to enable resilient, adaptive and real-time communications over unreliable and dynamic physical networks (PNets). The autonomous software agents comprising the communication middleware monitor their performance and the underlying PNet, and dynamically adapt the P2P overlay and migrate over the PNet in order to optimize communications according to the requirements of the federation and the current conditions of the PNet. Reliable communications is provided via redundancy within the communication middleware and intelligent migration of agents over the PNet. The proposed middleware integrates security methods in order to protect the communication infrastructure against attacks and provide privacy and anonymity to the participants of the federation. Experiments with an initial version of the communication middleware over a real-life networking testbed show that promising improvements can be obtained for unicast and group communications via the agent migration capability of our middleware.

  12. Milking tests on Murgese mares and the design of adapted stalls.

    PubMed

    Bellomo, F; Bianchi, B; D'Emilio, F P

    2005-01-01

    The results of research into the milking of mares of the Murgese breed are described. A comparison was made between hand and mechanical milking with two pulsation rates (120 and 140 cycles/min) with the objective of defining mechanical and operational solutions for the design or standardisation of machine milking of mares with special reference to the Murgese breed. The study was performed on four multiparous mares, after a suitable adaptation period. The trial lasted 45 days, during which the animals were milked twice a day. Research showed considerable advantages, both from productive and technical manipulation viewpoints, of milking this species by mechanical means, rather than by hand. Moreover, mechanical milking at 140 cycles/min provided better results than other techniques examined, as it is possible to obtain the best milk production, the smallest specific power consumption and, in addition, the highest working capacity and labour productivity. The adaptation of the animals to mechanical milking and the resultant production can be considered adequate. Mechanical and operating solutions are proposed for new plants, together with adaptations to ensure security in existing plants.

  13. Bayesian adaptive design: improving the effectiveness of monitoring of the Great Barrier Reef.

    PubMed

    Kang, Su Yun; McGree, James M; Drovandi, Christopher C; Caley, M Julian; Mengersen, Kerrie L

    2016-12-01

    Monitoring programs are essential for understanding patterns, trends, and threats in ecological and environmental systems. However, such programs are costly in terms of dollars, human resources, and technology, and complex in terms of balancing short- and long-term requirements. In this work, We develop new statistical methods for implementing cost-effective adaptive sampling and monitoring schemes for coral reef that can better utilize existing information and resources, and which can incorporate available prior information. Our research was motivated by developing efficient monitoring practices for Australia's Great Barrier Reef. We develop and implement two types of adaptive sampling schemes, static and sequential, and show that they can be more informative and cost-effective than an existing (nonadaptive) monitoring program. Our methods are developed in a Bayesian framework with a range of utility functions relevant to environmental monitoring. Our results demonstrate the considerable potential for adaptive design to support improved management outcomes in comparison to set-and-forget styles of surveillance monitoring.

  14. A fuzzy model based adaptive PID controller design for nonlinear and uncertain processes.

    PubMed

    Savran, Aydogan; Kahraman, Gokalp

    2014-03-01

    We develop a novel adaptive tuning method for classical proportional-integral-derivative (PID) controller to control nonlinear processes to adjust PID gains, a problem which is very difficult to overcome in the classical PID controllers. By incorporating classical PID control, which is well-known in industry, to the control of nonlinear processes, we introduce a method which can readily be used by the industry. In this method, controller design does not require a first principal model of the process which is usually very difficult to obtain. Instead, it depends on a fuzzy process model which is constructed from the measured input-output data of the process. A soft limiter is used to impose industrial limits on the control input. The performance of the system is successfully tested on the bioreactor, a highly nonlinear process involving instabilities. Several tests showed the method's success in tracking, robustness to noise, and adaptation properties. We as well compared our system's performance to those of a plant with altered parameters with measurement noise, and obtained less ringing and better tracking. To conclude, we present a novel adaptive control method that is built upon the well-known PID architecture that successfully controls highly nonlinear industrial processes, even under conditions such as strong parameter variations, noise, and instabilities.

  15. LISA Parameter Estimation using Numerical Merger Waveforms

    NASA Technical Reports Server (NTRS)

    Thorpe, J. I.; McWilliams, S.; Baker, J.

    2008-01-01

    Coalescing supermassive black holes are expected to provide the strongest sources for gravitational radiation detected by LISA. Recent advances in numerical relativity provide a detailed description of the waveforms of such signals. We present a preliminary study of LISA's sensitivity to waveform parameters using a hybrid numerical/analytic waveform describing the coalescence of two equal-mass, nonspinning black holes. The Synthetic LISA software package is used to simulate the instrument response and the Fisher information matrix method is used to estimate errors in the waveform parameters. Initial results indicate that inclusion of the merger signal can significantly improve the precision of some parameter estimates. For example, the median parameter errors for an ensemble of systems with total redshifted mass of 10(exp 6) deg M solar mass at a redshift of z is approximately 1 were found to decrease by a factor of slightly more than two when the merger was included.

  16. Efficacy of Various Waveforms to Support Geolocation

    DTIC Science & Technology

    2009-06-01

    the square root of the summed signal as shown in Figure 16. The resulting distribution of the decision variable with signal present is non- central ...resulting distribution for the case with no signal, i.e., noise only, is central Chi-squared with two degrees of freedom or Rayleigh for the case in...summing the waveform power weighted by time from the central time, and dividing this by the sum of the unweighted waveform power, or signal energy sE

  17. GRC GSFC TDRSS Waveform Metrics Report

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.

    2013-01-01

    The report presents software metrics and porting metrics for the GGT Waveform. The porting was from a ground-based COTS SDR, the SDR-3000, to the CoNNeCT JPL SDR. The report does not address any of the Operating Environment (OE) software development, nor the original TDRSS waveform development at GSFC for the COTS SDR. With regard to STRS, the report presents compliance data and lessons learned.

  18. Analysis and Application of LIDAR Waveform Data Using a Progressive Waveform Decomposition Method

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Zhang, Z.; Hu, X.; Li, Z.

    2011-09-01

    Due to rich information of a full waveform of airborne LiDAR (light detection and ranging) data, the analysis of full waveform has been an active area in LiDAR application. It is possible to digitally sample and store the entire reflected waveform of small-footprint instead of only discrete point clouds. Decomposition of waveform data, a key step in waveform data analysis, can be categorized to two typical methods: 1) the Gaussian modelling method such as the Non-linear least-squares (NLS) algorithm and the maximum likelihood estimation using the Exception Maximization (EM) algorithm. 2) pulse detection method—Average Square Difference Function (ASDF). However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform. In this paper, we proposed a fast algorithm—Progressive Waveform Decomposition (PWD) method to extract local maxims and fit the echo with Gaussian function, and calculate other parameters from the raw waveform data. On the one hand, experiments are implemented to evaluate the PWD method and the results demonstrate its robustness and efficiency. On the other hand, with the PWD parametric analysis of the full-waveform instead of a 3D point cloud, some special applications are investigated afterward.

  19. First-order design of a reflective viewfinder for adaptive optics ophthalmoscopy.

    PubMed

    Dubra, Alfredo; Sulai, Yusufu N

    2012-11-19

    Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. Diverting light from an existing pupil optical relay to the viewfinder relay allows switching field of view size. Design methods that meet all four centering and conjugation conditions using either a single concave mirror or with two concave mirrors forming an off-axis afocal telescope are presented. Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal viewfinder relay are introduced. Finally, a 2.2 × viewfinder mode is demonstrated in an AO scanning light ophthalmoscope.

  20. Active learning: effects of core training design elements on self-regulatory processes, learning, and adaptability.

    PubMed

    Bell, Bradford S; Kozlowski, Steve W J

    2008-03-01

    This article describes a comprehensive examination of the cognitive, motivational, and emotional processes underlying active learning approaches; their effects on learning and transfer; and the core training design elements (exploration, training frame, emotion control) and individual differences (cognitive ability, trait goal orientation, trait anxiety) that shape these processes. Participants (N = 350) were trained to operate a complex, computer-based simulation. Exploratory learning and error-encouragement framing had a positive effect on adaptive transfer performance and interacted with cognitive ability and dispositional goal orientation to influence trainees' metacognition and state goal orientation. Trainees who received the emotion-control strategy had lower levels of state anxiety. Implications for development of an integrated theory of active learning, learner-centered design, and research extensions are discussed.

  1. Two-Stage Adaptive Cutoff (TACO) Design for Building and Validating a Prognostic Biomarker Signature

    PubMed Central

    Polley, Mei-Yin C.; Polley, Eric C.; Huang, Erich P.; Freidlin, Boris; Simon, Richard

    2014-01-01

    Cancer biomarkers are frequently evaluated using archived specimens collected from previously conducted therapeutic trials. Routine collection and banking of high quality specimens is an expensive and time-consuming process. Therefore, care should be taken to preserve these precious resources. Here we propose a novel two-stage adaptive cutoff (TACO) design that affords the possibility to stop the biomarker study early if an evaluation of the model performance is unsatisfactory at an early stage, thereby allowing one to preserve the remaining specimens for future research. In addition, our design integrates important elements necessary to meet statistical rigor and practical demands for developing and validating a prognostic biomarker signature, including maintaining strict separation between the datasets used to build and evaluate the model and producing a locked-down signature to facilitate future validation. We conduct simulation studies to evaluate the operating characteristics of the proposed design. We show that under the null hypothesis when the model performance is deemed undesirable, the proposed design maintains type I error at the nominal level, has high probabilities of terminating the study early, and results in substantial savings in specimens. Under the alternative hypothesis, power is generally high when the total sample size and the targeted degree of improvement in prediction accuracy are reasonably large. We illustrate the use of the procedure with a dataset in patients with diffuse large-B-cell lymphoma. The practical aspects of the proposed designs are discussed. PMID:25263614

  2. Georgia tech catalog of gravitational waveforms

    NASA Astrophysics Data System (ADS)

    Jani, Karan; Healy, James; Clark, James A.; London, Lionel; Laguna, Pablo; Shoemaker, Deirdre

    2016-10-01

    This paper introduces a catalog of gravitational waveforms from the bank of simulations by the numerical relativity effort at Georgia Tech. Currently, the catalog consists of 452 distinct waveforms from more than 600 binary black hole simulations: 128 of the waveforms are from binaries with black hole spins aligned with the orbital angular momentum, and 324 are from precessing binary black hole systems. The waveforms from binaries with non-spinning black holes have mass-ratios q = m 1/m 2 ≤ 15, and those with precessing, spinning black holes have q ≤ 8. The waveforms expand a moderate number of orbits in the late inspiral, the burst during coalescence, and the ring-down of the final black hole. Examples of waveforms in the catalog matched against the widely used approximate models are presented. In addition, predictions of the mass and spin of the final black hole by phenomenological fits are tested against the results from the simulation bank. The role of the catalog in interpreting the GW150914 event and future massive binary black-hole search in LIGO is discussed. The Georgia Tech catalog is publicly available at einstein.gatech.edu/catalog.

  3. Modeling measured glottal volume velocity waveforms.

    PubMed

    Verneuil, Andrew; Berry, David A; Kreiman, Jody; Gerratt, Bruce R; Ye, Ming; Berke, Gerald S

    2003-02-01

    The source-filter theory of speech production describes a glottal energy source (volume velocity waveform) that is filtered by the vocal tract and radiates from the mouth as phonation. The characteristics of the volume velocity waveform, the source that drives phonation, have been estimated, but never directly measured at the glottis. To accomplish this measurement, constant temperature anemometer probes were used in an in vivo canine constant pressure model of phonation. A 3-probe array was positioned supraglottically, and an endoscopic camera was positioned subglottically. Simultaneous recordings of airflow velocity (using anemometry) and glottal area (using stroboscopy) were made in 3 animals. Glottal airflow velocities and areas were combined to produce direct measurements of glottal volume velocity waveforms. The anterior and middle parts of the glottis contributed significantly to the volume velocity waveform, with less contribution from the posterior part of the glottis. The measured volume velocity waveforms were successfully fitted to a well-known laryngeal airflow model. A noninvasive measured volume velocity waveform holds promise for future clinical use.

  4. A generalizable adaptive brain-machine interface design for control of anesthesia.

    PubMed

    Yuxiao Yang; Shanechi, Maryam M

    2015-08-01

    Brain-machine interfaces (BMIs) for closed-loop control of anesthesia have the potential to automatically monitor and control brain states under anesthesia. Since a variety of anesthetic states are needed in different clinical scenarios, designing a generalizable BMI architecture that can control a wide range of anesthetic states is essential. In addition, drug dynamics are non-stationary over time and could change with the depth of anesthesia. Hence for precise control, a BMI needs to track these non-stationarities online. Here we design a BMI architecture that generalizes to control of various anesthetic states and their associated neural signatures, and is adaptive to time-varying drug dynamics. We provide a systematic approach to build general parametric models that quantify the anesthetic state and describe the drug dynamics. Based on these models, we develop an adaptive closed-loop controller within the framework of stochastic optimal feedback control. This controller tracks the non-stationarities in drug dynamics, achieves tight control in a time-varying environment, and removes the need for an offline system identification session. For robustness, the BMI also ensures small drug infusion rate variations at steady state. We test the BMI architecture for control of two common anesthetic states, i.e., burst suppression in medically-induced coma and unconsciousness in general anesthesia. Using numerical experiments, we find that the BMI generalizes to control of both these anesthetic states; in a time-varying environment, even without initial knowledge of model parameters, the BMI accurately controls these two different anesthetic states, reducing bias and error more than 70 times and 9 times, respectively, compared with a non-adaptive system.

  5. A texture-analysis-based design method for self-adaptive focus criterion function.

    PubMed

    Liang, Q; Qu, Y F

    2012-05-01

    Autofocusing (AF) criterion functions are critical to the performance of a passive autofocusing system in automatic video microscopy. Most of the autofocusing criterion functions proposed are dependent on the imaging system and image captured by the objective being focused or ranged. This dependence destabilizes the performance of the system when the criterion functions are applied to objectives with different characteristics. In this paper, a new design method for autofocusing criterion functions is introduced. This method enables the system to have the ability to tell the texture directional information of the objective. Based on this information, the optimal focus criterion function specific to one texture direction is designed, voiding blindly using autofocusing functions which cannot perform well when applied to the certain surface and can even lead to failure of the whole process. In this way, we improved the self-adaptability, robustness, reliability and focusing accuracy of the algorithm. First, the grey-level co-occurrence matrices of real-time images are calculated in four directions. Next, the contrast values of the four matrices are computed and then compared. The result reflects the directional information of the measured objective surfaces. Finally, with the directional information, an adaptive criterion function is constructed. To demonstrate the effectiveness of the new focus algorithm, we conducted experiments on different texture surfaces and compared the results with those obtained by existing algorithms. The proposed algorithm excellently performs with different measured objectives.

  6. Design of a knee joint mechanism that adapts to individual physiology.

    PubMed

    Jiun-Yih Kuan; Pasch, Kenneth A; Herr, Hugh M

    2014-01-01

    This paper describes the design of a new knee joint mechanism, called the Adaptive Coupling Joint (ACJ). The new mechanism has an adaptive trajectory of the center of rotations (COR) that automatically matches those of the attached biological joint. The detailed design is presented as well as characterization results of the ACJ. Conventional exoskeleton and assistive devices usually consider limb joints as a one to three degrees of freedom (DOFs) joint synthesized by multiple one-DOF hinge joints in a single plane. However, the biological joints are complex and usually rotate with respect to a changing COR. As a result, the mismatch between limb joint motion and mechanical interface motion can lead to forces that cause undesired ligament and muscle length changes and internal mechanical changes. These undesired changes contribute to discomfort, as well as to the slippage and sluggish interaction between humans and devices. It is shown that the ACJ can transmit planetary torques from either active or passive devices to the limbs without altering the normal biological joint motion.

  7. Design, Fabrication, and Testing of SMA Enabled Adaptive Chevrons for Jet Noise Reduction

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Buehrle, Ralph D.; Cano, Roberto J.; Fleming, Gary A.

    2004-01-01

    This study presents the status and results from an effort to design, fabricate, and test an adaptive jet engine chevron concept based upon embedding shape memory alloy (SMA) actuators in a composite laminate, termed a SMA hybrid composite (SMAHC). The approach for fabricating the adaptive SMAHC chevrons involves embedding prestrained Nitinol actuators on one side of the mid-plane of the composite laminate such that thermal excitation generates a thermal moment and deflects the structure. A glass-epoxy pre-preg/Nitinol ribbon material system and a vacuum hot press consolidation approach are employed. A versatile test system for control and measurement of the chevron deflection performance is described. Projection moire interferometry (PMI) is used for global deformation measurement and infrared (IR) thermography is used for 2-D temperature measurement and feedback control. A recently commercialized constitutive model for SMA and SMAHC materials is used in the finite element code ABAQUS to perform nonlinear static analysis of the chevron prototypes. Excellent agreement is achieved between the predicted and measured chevron deflection performance, thereby validating the design tool. Although the performance results presented in this paper fall short of the requirement, the concept is proven and an approach for achieving the performance objectives is evident.

  8. Design, fabrication, and testing of SMA-enabled adaptive chevrons for jet noise reduction

    NASA Astrophysics Data System (ADS)

    Turner, Travis L.; Buehrle, Ralph D.; Cano, Roberto J.; Fleming, Gary A.

    2004-07-01

    This study presents the status and results from an effort to design, fabricate, and test an adaptive jet engine chevron concept based upon embedding shape memory alloy (SMA) actuators in a composite laminate, termed a SMA hybrid composite (SMAHC). The approach for fabricating the adaptive SMAHC chevrons involves embedding prestrained Nitinol actuators on one side of the mid-plane of the composite laminate such that thermal excitation generates a thermal moment and deflects the structure. A glass-epoxy pre-preg/Nitinol ribbon material system and a vacuum hot press consolidation approach are employed. A versatile test system for control and measurement of the chevron deflection performance is described. Projection moire interferometry (PMI) is used for global deformation measurement and infrared (IR) thermography is used for 2-D temperature measurement and feedback control. A recently commercialized constitutive model for SMA and SMAHC materials is used in the finite element code ABAQUS to perform nonlinear static analysis of the chevron prototypes. Excellent agreement is achieved between the predicted and measured chevron deflection performance, thereby validating the design tool. Although the performance results presented in this paper fall short of the requirement, the concept is proven and an approach for achieving the performance objectives is evident.

  9. Optimizing trial design in pharmacogenetics research: comparing a fixed parallel group, group sequential, and adaptive selection design on sample size requirements.

    PubMed

    Boessen, Ruud; van der Baan, Frederieke; Groenwold, Rolf; Egberts, Antoine; Klungel, Olaf; Grobbee, Diederick; Knol, Mirjam; Roes, Kit

    2013-01-01

    Two-stage clinical trial designs may be efficient in pharmacogenetics research when there is some but inconclusive evidence of effect modification by a genomic marker. Two-stage designs allow to stop early for efficacy or futility and can offer the additional opportunity to enrich the study population to a specific patient subgroup after an interim analysis. This study compared sample size requirements for fixed parallel group, group sequential, and adaptive selection designs with equal overall power and control of the family-wise type I error rate. The designs were evaluated across scenarios that defined the effect sizes in the marker positive and marker negative subgroups and the prevalence of marker positive patients in the overall study population. Effect sizes were chosen to reflect realistic planning scenarios, where at least some effect is present in the marker negative subgroup. In addition, scenarios were considered in which the assumed 'true' subgroup effects (i.e., the postulated effects) differed from those hypothesized at the planning stage. As expected, both two-stage designs generally required fewer patients than a fixed parallel group design, and the advantage increased as the difference between subgroups increased. The adaptive selection design added little further reduction in sample size, as compared with the group sequential design, when the postulated effect sizes were equal to those hypothesized at the planning stage. However, when the postulated effects deviated strongly in favor of enrichment, the comparative advantage of the adaptive selection design increased, which precisely reflects the adaptive nature of the design.

  10. Modelling Sensor and Target effects on LiDAR Waveforms

    NASA Astrophysics Data System (ADS)

    Rosette, J.; North, P. R.; Rubio, J.; Cook, B. D.; Suárez, J.

    2010-12-01

    The aim of this research is to explore the influence of sensor characteristics and interactions with vegetation and terrain properties on the estimation of vegetation parameters from LiDAR waveforms. This is carried out using waveform simulations produced by the FLIGHT radiative transfer model which is based on Monte Carlo simulation of photon transport (North, 1996; North et al., 2010). The opportunities for vegetation analysis that are offered by LiDAR modelling are also demonstrated by other authors e.g. Sun and Ranson, 2000; Ni-Meister et al., 2001. Simulations from the FLIGHT model were driven using reflectance and transmittance properties collected from the Howland Research Forest, Maine, USA in 2003 together with a tree list for a 200m x 150m area. This was generated using field measurements of location, species and diameter at breast height. Tree height and crown dimensions of individual trees were calculated using relationships established with a competition index determined for this site. Waveforms obtained by the Laser Vegetation Imaging Sensor (LVIS) were used as validation of simulations. This provided a base from which factors such as slope, laser incidence angle and pulse width could be varied. This has enabled the effect of instrument design and laser interactions with different surface characteristics to be tested. As such, waveform simulation is relevant for the development of future satellite LiDAR sensors, such as NASA’s forthcoming DESDynI mission (NASA, 2010), which aim to improve capabilities of vegetation parameter estimation. ACKNOWLEDGMENTS We would like to thank scientists at the Biospheric Sciences Branch of NASA Goddard Space Flight Center, in particular to Jon Ranson and Bryan Blair. This work forms part of research funded by the NASA DESDynI project and the UK Natural Environment Research Council (NE/F021437/1). REFERENCES NASA, 2010, DESDynI: Deformation, Ecosystem Structure and Dynamics of Ice. http

  11. Method and Apparatus for Flight Data Acquisition using an Optimized Multiple Frequency Waveform

    NASA Technical Reports Server (NTRS)

    Duke, Bryan D. (Inventor)

    2002-01-01

    The present invention comprises a method and apparatus that generates a waveform consisting of an arbitrary number of frequency sweeps combined from adding and subtracting mini frequency sweeps. Optimization routines determine the best combination order of frequency sweep to minimize or maximize design criteria such is aerodynamic surface deflection or maximum command rate of the wave form. The invention allows for arbitrary output timing, or commands per second issued for the desired waveform, arbitrary starting and ending frequencies and amplitudes, arbitrary number of frequency sweep components, arbitrary frequency sweep exponent, arbitrary amplitude sweep exponent, and arbitrary waveform length. For a given frequency range and sweep exponent, amplitude range and sweep exponent, desired total waveform time and number of frequency sweep components, the algorithm can determine the optimum arrangement of the components to minimize the maximum amplitude or rate.

  12. 4-bit Bipolar Triangle Voltage Waveform Generator Using Single-Flux-Quantum Circuit

    NASA Astrophysics Data System (ADS)

    Watanabe, Tomoki; Takahashi, Yoshitaka; Shimada, Hiroshi; Maezawa, Masaaki; Mizugaki, Yoshinao

    SFQ digital-to-analog converters (DACs) are one of the candidates for AC voltage standards. We have proposed SFQ-DACs based on frequency modulation (FM). Bipolar output is required for applications of AC voltage standards, while our previous SFQ-DACs generated only positive voltages. In this paper, we present our design of a 4-bit bipolar triangle voltage waveform generator comprising an SFQ-DAC. The waveform generator has two output ports. Synthesized half-period waveforms are alternately generated in one of the output ports. The bipolar output is realized by observing the differential voltage between the ports. We confirmed a 72-μVPP bipolar triangle voltage waveform at the frequency of 35.7 Hz.

  13. The Classroom Adaptation Scale: A Behavior Rating Scale Designed to Screen Primary Grade Children for School Adaptation Problems.

    ERIC Educational Resources Information Center

    Virbickis, Joseph A.

    After a brief historical review of the background and research, the paper focuses on development of a teacher-administered behavior rating scale to screen for school adaptation problems on a large scale basis using as Ss 15 primary grade teachers and their ratings of 315 primary grade children (ages 6-to-10 years) in their classes. A 16-item…

  14. Testing vision with angular and radial multifocal designs using Adaptive Optics.

    PubMed

    Vinas, Maria; Dorronsoro, Carlos; Gonzalez, Veronica; Cortes, Daniel; Radhakrishnan, Aiswaryah; Marcos, Susana

    2017-03-01

    Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye's aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an "ideal observer" purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance.

  15. An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures

    PubMed Central

    Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf

    2016-01-01

    Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762

  16. Range Profile Specific Optimal Waveforms for Minimum Mean Square Error Estimation

    DTIC Science & Technology

    2010-01-01

    requires as input the result of a single dwell. This is because of the effect of changing a fil- ter can be observed by simply processing the radar return...only be observed by transmitting another dwell. We have posited a joint measurement and adaptation process that assumes range cell specific waveforms...The observation resulting from using waveform s(l) is assumed to be given by ỹ(l) = AT (l)s(l) + ṽ(l) (1) where ṽ(l) is the measurement noise and A

  17. Complex Adaptive Systems of Systems (CASoS) engineering and foundations for global design.

    SciTech Connect

    Brodsky, Nancy S.; Finley, Patrick D.; Beyeler, Walter Eugene; Brown, Theresa Jean; Linebarger, John Michael; Moore, Thomas W.; Glass, Robert John, Jr.; Maffitt, S. Louise; Mitchell, Michael David; Ames, Arlo Leroy

    2012-01-01

    Complex Adaptive Systems of Systems, or CASoS, are vastly complex ecological, sociological, economic and/or technical systems which must be recognized and reckoned with to design a secure future for the nation and the world. Design within CASoS requires the fostering of a new discipline, CASoS Engineering, and the building of capability to support it. Towards this primary objective, we created the Phoenix Pilot as a crucible from which systemization of the new discipline could emerge. Using a wide range of applications, Phoenix has begun building both theoretical foundations and capability for: the integration of Applications to continuously build common understanding and capability; a Framework for defining problems, designing and testing solutions, and actualizing these solutions within the CASoS of interest; and an engineering Environment required for 'the doing' of CASoS Engineering. In a secondary objective, we applied CASoS Engineering principles to begin to build a foundation for design in context of Global CASoS

  18. Adaptive design optimization: a mutual information-based approach to model discrimination in cognitive science.

    PubMed

    Cavagnaro, Daniel R; Myung, Jay I; Pitt, Mark A; Kujala, Janne V

    2010-04-01

    Discriminating among competing statistical models is a pressing issue for many experimentalists in the field of cognitive science. Resolving this issue begins with designing maximally informative experiments. To this end, the problem to be solved in adaptive design optimization is identifying experimental designs under which one can infer the underlying model in the fewest possible steps. When the models under consideration are nonlinear, as is often the case in cognitive science, this problem can be impossible to solve analytically without simplifying assumptions. However, as we show in this letter, a full solution can be found numerically with the help of a Bayesian computational trick derived from the statistics literature, which recasts the problem as a probability density simulation in which the optimal design is the mode of the density. We use a utility function based on mutual information and give three intuitive interpretations of the utility function in terms of Bayesian posterior estimates. As a proof of concept, we offer a simple example application to an experiment on memory retention.

  19. The optical design of a visible adaptive optics system for the Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Kopon, Derek

    The Magellan Adaptive Optics system will achieve first light in November of 2012. This AO system contains several subsystems including the 585-actuator concave adaptive secondary mirror, the Calibration Return Optic (CRO) alignment and calibration system, the CLIO 1-5 microm IR science camera, the movable guider camera and active optics assembly, and the W-Unit, which contains both the Pyramid Wavefront Sensor (PWFS) and the VisAO visible science camera. In this dissertation, we present details of the design, fabrication, assembly, alignment, and laboratory performance of the VisAO camera and its optical components. Many of these components required a custom design, such as the Spectral Differential Imaging Wollaston prisms and filters and the coronagraphic spots. One component, the Atmospheric Dispersion Corrector (ADC), required a unique triplet design that had until now never been fabricated and tested on sky. We present the design, laboratory, and on-sky results for our triplet ADC. We also present details of the CRO test setup and alignment. Because Magellan is a Gregorian telescope, the ASM is a concave ellipsoidal mirror. By simulating a star with a white light point source at the far conjugate, we can create a double-pass test of the whole system without the need for a real on-sky star. This allows us to test the AO system closed loop in the Arcetri test tower at its nominal design focal length and optical conjugates. The CRO test will also allow us to calibrate and verify the system off-sky at the Magellan telescope during commissioning and periodically thereafter. We present a design for a possible future upgrade path for a new visible Integral Field Spectrograph. By integrating a fiber array bundle at the VisAO focal plane, we can send light to a pre-existing facility spectrograph, such as LDSS3, which will allow 20 mas spatial sampling and R˜1,800 spectra over the band 0.6-1.05 microm. This would be the highest spatial resolution IFU to date, either

  20. Harmonic minimization waveforms for modulated heating experiments at HAARP

    NASA Astrophysics Data System (ADS)

    Jin, G.; Spasojevic, M.; Cohen, M. B.; Inan, U. S.

    2012-11-01

    Modulated High Frequency (few MHz) heating of the D-region ionosphere under the auroral electrojet is capable of generating extremely low frequency (ELF) radio waves in the few kilohertz range by affecting the conductivity of the D-region. The HF heating is nonlinear and results in the generation of harmonics at integer multiples of the ELF modulation frequency with ∼1% of the total power outside the fundamental when sinusoidal amplitude modulation is applied to the HF carrier. For the purpose of harmonic minimization, we present a modulation scheme designed to create a sinusoidal change in the Hall conductivity at a particular altitude in the ionosphere. The modulation waveform is generated by inverting a numerical HF heating model, starting from the desired conductivity time series, and obtaining the HF power envelope at the bottom of the ionosphere. The inverted envelopes (referred to as inv-sin waveforms) are highly sensitive to the assumed ionospheric density profile and simulations indicate that these waveforms have less harmonic distortion compared to sinusoidal modulation when the actual ionospheric density is similar to or less dense than the one assumed. Experimental results indicate that sinusoidal amplitude modulation may still be preferred since it is more robust to the highly variable ionospheric profile while square wave modulation is more efficient in generation of ELF waves when harmonic distortion is not important. The inv-sin waveforms are more efficient than sinusoidal modulation while still suffering from less harmonic distortion than square wave modulation suggesting a tradeoff between harmonic distortion and ELF generation efficiency.

  1. A Review on Effectiveness and Adaptability of the Design-Build Method

    NASA Astrophysics Data System (ADS)

    Kudo, Masataka; Miyatake, Ichiro; Baba, Kazuhito; Yokoi, Hiroyuki; Fueta, Toshiharu

    In the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), various approaches have been taken for efficient implementation of public works projects, one of which is the ongoing use of the design-build method on a trial basis, as a means to utilize the technical skills and knowledge of private companies. In 2005, MLIT further introduced the a dvanced technical proposal type, a kind of the comprehensive evaluation method, as part of its efforts to improve tendering and contracting systems. Meanwhile, although the positive effect of the design build method has been reported, it has not been widely published, which may be one of the reasons that the number of MLIT projects using the design-build method is declining year by year. In this context, this paper discusses the result and review of the study concerning the extent of flexibility allowed for the process and design (proposal) of public work projects, and the follow-up surveys of the actual test case projects, conducted as basic researches to examine the measure to expand and promote the use of the design-build method. The study objects were selected from the tunnel construction projects using the shield tunneling method for developing the common utility duct, and the bridge construction projects ordering construction of supers tructure work and substructure work in a single contract. In providing the result and review of the studies, the structures and the temporary installations were separately examined, and effectiveness and adaptability of the design-build method was discussed for each, respectively.

  2. A design and analysis approach for drag reduction on aircraft with adaptive lifting surfaces

    NASA Astrophysics Data System (ADS)

    Cusher, Aaron Anthony

    Adaptive lifting surfaces, which can be tailored for different flight conditions, have been shown to be beneficial for drag reduction when compared with conventional non-adaptive surfaces. Applying multiple trailing-edge flaps along the wing span allows for the redistribution of lift to suit different flight conditions. The current approach uses the trailing-edge flap distribution to reduce both induced- and profile- components of drag with a trim constraint. Induced drag is reduced by optimally redistributing the lift between the lifting surfaces and along the span of each surface. Profile drag is reduced through the use of natural laminar flow airfoils, which maintain distinct low-drag-ranges (drag buckets) surrounding design lift values. The low-drag-ranges can be extended to include off-design values through small flap deflections, similar to cruise flaps. Trim is constrained for a given static margin by considering longitudinal pitching moment contributions from changes in airfoil section due to individual flap deflections, and from the redistribution of fore-and-aft lift due to combination of flap deflections. The approach uses the concept of basic and additional lift to linearlize the problem, which allows for standard constrained-minimization theory to be employed for determining optimal flap-angle solutions. The resulting expressions for optimal flap-angle solutions are presented as simple matrix equations. This work presents a design and analysis approach which is used to produce flap-angle solutions that independently reduce induced, profile, and total drag. Total drag is defined to be the sum of the induced- and profile-components of drag. The general drag reduction approach is adapted for each specific situation to develop specific drag reduction schemes that are applied to single- and multiple-surface configurations. Successful results show that, for the application of the induced drag reduction schemes on a tailless aircraft, near-elliptical lift

  3. Using Tests Designed to Measure Individual Sensorimotor Subsystem Perfomance to Predict Locomotor Adaptability

    NASA Technical Reports Server (NTRS)

    Peters, B. T.; Caldwell, E. E.; Batson, C. D.; Guined, J. R.; DeDios, Y. E.; Stepanyan, V.; Gadd, N. E.; Szecsy, D. L.; Mulavara, A. P.; Seidler, R. D.; Bloomberg, J. J.

    2014-01-01

    Astronauts experience sensorimotor disturbances during the initial exposure to microgravity and during the readapation phase following a return to a gravitational environment. These alterations may lead to disruption in the ability to perform mission critical functions during and after these gravitational transitions. Astronauts show significant inter-subject variation in adaptive capability following gravitational transitions. The way each individual's brain synthesizes the available visual, vestibular and somatosensory information is likely the basis for much of the variation. Identifying the presence of biases in each person's use of information available from these sensorimotor subsystems and relating it to their ability to adapt to a novel locomotor task will allow us to customize a training program designed to enhance sensorimotor adaptability. Eight tests are being used to measure sensorimotor subsystem performance. Three of these use measures of body sway to characterize balance during varying sensorimotor challenges. The effect of vision is assessed by repeating conditions with eyes open and eyes closed. Standing on foam, or on a support surface that pitches to maintain a constant ankle angle provide somatosensory challenges. Information from the vestibular system is isolated when vision is removed and the support surface is compromised, and it is challenged when the tasks are done while the head is in motion. The integration and dominance of visual information is assessed in three additional tests. The Rod & Frame Test measures the degree to which a subject's perception of the visual vertical is affected by the orientation of a tilted frame in the periphery. Locomotor visual dependence is determined by assessing how much an oscillating virtual visual world affects a treadmill-walking subject. In the third of the visual manipulation tests, subjects walk an obstacle course while wearing up-down reversing prisms. The two remaining tests include direct

  4. Adaptive neural control design for nonlinear distributed parameter systems with persistent bounded disturbances.

    PubMed

    Wu, Huai-Ning; Li, Han-Xiong

    2009-10-01

    In this paper, an adaptive neural network (NN) control with a guaranteed L(infinity)-gain performance is proposed for a class of parabolic partial differential equation (PDE) systems with unknown nonlinearities and persistent bounded disturbances. Initially, Galerkin method is applied to the PDE system to derive a low-order ordinary differential equation (ODE) system that accurately describes the dynamics of the dominant (slow) modes of the PDE system. Subsequently, based on the low-order slow model and the Lyapunov technique, an adaptive modal feedback controller is developed such that the closed-loop slow system is semiglobally input-to-state practically stable (ISpS) with an L(infinity)-gain performance. In the proposed control scheme, a radial basis function (RBF) NN is employed to approximate the unknown term in the derivative of the Lyapunov function due to the unknown system nonlinearities. The outcome of the adaptive L(infinity)-gain control problem is formulated as a linear matrix inequality (LMI) problem. Moreover, by using the existing LMI optimization technique, a suboptimal controller is obtained in the sense of minimizing an upper bound of the L(infinity)-gain, while control constraints are respected. Furthermore, it is shown that the proposed controller can ensure the semiglobal input-to-state practical stability and L(infinity)-gain performance of the closed-loop PDE system. Finally, by applying the developed design method to the temperature profile control of a catalytic rod, the achieved simulation results show the effectiveness of the proposed controller.

  5. Flight control design using a blend of modern nonlinear adaptive and robust techniques

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolong

    In this dissertation, the modern control techniques of feedback linearization, mu synthesis, and neural network based adaptation are used to design novel control laws for two specific applications: F/A-18 flight control and reusable launch vehicle (an X-33 derivative) entry guidance. For both applications, the performance of the controllers is assessed. As a part of a NASA Dryden program to develop and flight test experimental controllers for an F/A-18 aircraft, a novel method of combining mu synthesis and feedback linearization is developed to design longitudinal and lateral-directional controllers. First of all, the open-loop and closed-loop dynamics of F/A-18 are investigated. The production F/A-18 controller as well as the control distribution mechanism are studied. The open-loop and closed-loop handling qualities of the F/A-18 are evaluated using low order transfer functions. Based on this information, a blend of robust mu synthesis and feedback linearization is used to design controllers for a low dynamic pressure envelope of flight conditions. For both the longitudinal and the lateral-directional axes, a robust linear controller is designed for a trim point in the center of the envelope. Then by including terms to cancel kinematic nonlinearities and variations in the aerodynamic forces and moments over the flight envelope, a complete nonlinear controller is developed. In addition, to compensate for the model uncertainty, linearization error and variations between operating points, neural network based adaptation is added to the designed longitudinal controller. The nonlinear simulations, robustness and handling qualities analysis indicate that the performance is similar to or better than that for the production F/A-18 controllers. When the dynamic pressure is very low, the performance of both the experimental and the production flight controllers is degraded, but Level I handling qualities are still achieved. A new generation of Reusable Launch Vehicles

  6. Experimental Investigation on Adaptive Robust Controller Designs Applied to Constrained Manipulators

    PubMed Central

    Nogueira, Samuel L.; Pazelli, Tatiana F. P. A. T.; Siqueira, Adriano A. G.; Terra, Marco H.

    2013-01-01

    In this paper, two interlaced studies are presented. The first is directed to the design and construction of a dynamic 3D force/moment sensor. The device is applied to provide a feedback signal of forces and moments exerted by the robotic end-effector. This development has become an alternative solution to the existing multi-axis load cell based on static force and moment sensors. The second one shows an experimental investigation on the performance of four different adaptive nonlinear ℋ∞ control methods applied to a constrained manipulator subject to uncertainties in the model and external disturbances. Coordinated position and force control is evaluated. Adaptive procedures are based on neural networks and fuzzy systems applied in two different modeling strategies. The first modeling strategy requires a well-known nominal model for the robot, so that the intelligent systems are applied only to estimate the effects of uncertainties, unmodeled dynamics and external disturbances. The second strategy considers that the robot model is completely unknown and, therefore, intelligent systems are used to estimate these dynamics. A comparative study is conducted based on experimental implementations performed with an actual planar manipulator and with the dynamic force sensor developed for this purpose. PMID:23598503

  7. Design and evaluation of a software prototype for participatory planning of environmental adaptations.

    PubMed

    Eriksson, J; Ek, A; Johansson, G

    2000-03-01

    A software prototype to support the planning process for adapting home and work environments for people with physical disabilities was designed and later evaluated. The prototype exploits low-cost three-dimensional (3-D) graphics products in the home computer market. The essential features of the prototype are: interactive rendering with optional hardware acceleration, interactive walk-throughs, direct manipulation tools for moving objects and measuring distances, and import of 3-D-objects from a library. A usability study was conducted, consisting of two test sessions (three weeks apart) and a final interview. The prototype was then tested and evaluated by representatives of future users: five occupational therapist students, and four persons with physical disability, with no previous experience of the prototype. Emphasis in the usability study was placed on the prototype's efficiency and learnability. We found that it is possible to realise a planning tool for environmental adaptations, both regarding usability and technical efficiency. The usability evaluation confirms our findings from previous case studies, regarding the relevance and positive attitude towards this kind of planning tool. Although the prototype was found to be satisfactorily efficient for the basic tasks, the paper presents several suggestions for improvement of future prototype versions.

  8. Design and simulation of adaptive optics controller based on mixed sensitivity H∞ control

    NASA Astrophysics Data System (ADS)

    Song, Dingan; Li, Xinyang; Peng, Zhenming

    2016-10-01

    Optical systems such as telescopes are very complex, and their model usually with the uncertainty. To deal with the uncertainty of adaptive optics system and improve system robust stability, the mixed sensitivity H-infinity control has been introduced to design system controller. In order to testify the validity, wavefront aberration correction capability, as well as the robust stability, has been compared between the mixed sensitivity H-infinity controller and the classic integral controller. The computer simulation results demonstrate that the system with the mixed sensitivity H-infinity controller, while can't guarantee a better correction performance, has greater robust stability than the one with the classic integral controller. That is to say, greater robust stability is achieved at the expense of the correction capability in the system with H-infinity controller. Moreover, the greater the uncertainty is, the more proceeds the mixed sensitivity H-infinity controller will produce. It proves the efficiency of the mixed sensitivity H-infinity controller in dealing with the uncertainty of adaptive optics system.

  9. Dynamic modeling, property investigation, and adaptive controller design of serial robotic manipulators modeled with structural compliance

    NASA Technical Reports Server (NTRS)

    Tesar, Delbert; Tosunoglu, Sabri; Lin, Shyng-Her

    1990-01-01

    Research results on general serial robotic manipulators modeled with structural compliances are presented. Two compliant manipulator modeling approaches, distributed and lumped parameter models, are used in this study. System dynamic equations for both compliant models are derived by using the first and second order influence coefficients. Also, the properties of compliant manipulator system dynamics are investigated. One of the properties, which is defined as inaccessibility of vibratory modes, is shown to display a distinct character associated with compliant manipulators. This property indicates the impact of robot geometry on the control of structural oscillations. Example studies are provided to illustrate the physical interpretation of inaccessibility of vibratory modes. Two types of controllers are designed for compliant manipulators modeled by either lumped or distributed parameter techniques. In order to maintain the generality of the results, neither linearization is introduced. Example simulations are given to demonstrate the controller performance. The second type controller is also built for general serial robot arms and is adaptive in nature which can estimate uncertain payload parameters on-line and simultaneously maintain trajectory tracking properties. The relation between manipulator motion tracking capability and convergence of parameter estimation properties is discussed through example case studies. The effect of control input update delays on adaptive controller performance is also studied.

  10. Experimental investigation on adaptive robust controller designs applied to constrained manipulators.

    PubMed

    Nogueira, Samuel L; Pazelli, Tatiana F P A T; Siqueira, Adriano A G; Terra, Marco H

    2013-04-18

    In this paper, two interlaced studies are presented. The first is directed to the design and construction of a dynamic 3D force/moment sensor. The device is applied to provide a feedback signal of forces and moments exerted by the robotic end-effector. This development has become an alternative solution to the existing multi-axis load cell based on static force and moment sensors. The second one shows an experimental investigation on the performance of four different adaptive nonlinear H∞ control methods applied to a constrained manipulator subject to uncertainties in the model and external disturbances. Coordinated position and force control is evaluated. Adaptive procedures are based on neural networks and fuzzy systems applied in two different modeling strategies. The first modeling strategy requires a well-known nominal model for the robot, so that the intelligent systems are applied only to estimate the effects of uncertainties, unmodeled dynamics and external disturbances. The second strategy considers that the robot model is completely unknown and, therefore, intelligent systems are used to estimate these dynamics. A comparative study is conducted based on experimental implementations performed with an actual planar manipulator and with the dynamic force sensor developed for this purpose.

  11. Experimental evaluation of shape memory alloy actuation technique in adaptive antenna design concepts

    NASA Technical Reports Server (NTRS)

    Kefauver, W. Neill; Carpenter, Bernie F.

    1994-01-01

    Creation of an antenna system that could autonomously adapt contours of reflecting surfaces to compensate for structural loads induced by a variable environment would maximize performance of space-based communication systems. Design of such a system requires the comprehensive development and integration of advanced actuator, sensor, and control technologies. As an initial step in this process, a test has been performed to assess the use of a shape memory alloy as a potential actuation technique. For this test, an existing, offset, cassegrain antenna system was retrofit with a subreflector equipped with shape memory alloy actuators for surface contour control. The impacts that the actuators had on both the subreflector contour and the antenna system patterns were measured. The results of this study indicate the potential for using shape memory alloy actuation techniques to adaptively control antenna performance; both variations in gain and beam steering capabilities were demonstrated. Future development effort is required to evolve this potential into a useful technology for satellite applications.

  12. First-order design of off-axis reflective ophthalmic adaptive optics systems using afocal telescopes

    NASA Astrophysics Data System (ADS)

    Gómez-Vieyra, Armando; Dubra, Alfredo; Williams, David R.; Malacara-Hernández, Daniel

    2009-09-01

    Scanning laser ophthalmoscopes (SLOs) and optical coherence tomographs are the state-of-the-art retinal imaging instruments, and are essential for early and reliable diagnosis of eye disease. Recently, with the incorporation of adaptive optics (AO), these instruments have started to deliver near diffraction-limited performance in both humans and animal models, enabling the resolution of the retinal ganglion cell bodies, their processes, the cone photoreceptor and the retinal pigment epithelial cells mosaics. Unfortunately, these novel instruments have not delivered consistent performance across human subjects and animal models. One of the limitations of current instruments is the astigmatism in the pupil and imaging planes, which degrades image quality, by preventing the wavefront sensor from measuring aberrations with high spatial content. This astigmatism is introduced by the sequence of off-axis reflective elements, typically spherical mirrors, used for relaying pupil and imaging planes. Expressions for minimal astigmatism on the image and pupil planes in off-axis reflective afocal telescopes formed by pairs of spherical mirrors are presented. The formulas, derived from the marginal ray fans equation, are valid for small angles of incidence (<=15°), and can be used to design laser cavities, spectrographs and vision adaptive optics systems. An example related to this last application is discussed.

  13. Design of Robust Adaptive Unbalance Response Controllers for Rotors with Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Knospe, Carl R.; Tamer, Samir M.; Fedigan, Stephen J.

    1996-01-01

    Experimental results have recently demonstrated that an adaptive open loop control strategy can be highly effective in the suppression of unbalance induced vibration on rotors supported in active magnetic bearings. This algorithm, however, relies upon a predetermined gain matrix. Typically, this matrix is determined by an optimal control formulation resulting in the choice of the pseudo-inverse of the nominal influence coefficient matrix as the gain matrix. This solution may result in problems with stability and performance robustness since the estimated influence coefficient matrix is not equal to the actual influence coefficient matrix. Recently, analysis tools have been developed to examine the robustness of this control algorithm with respect to structured uncertainty. Herein, these tools are extended to produce a design procedure for determining the adaptive law's gain matrix. The resulting control algorithm has a guaranteed convergence rate and steady state performance in spite of the uncertainty in the rotor system. Several examples are presented which demonstrate the effectiveness of this approach and its advantages over the standard optimal control formulation.

  14. Integrated System Design: Promoting the Capacity of Sociotechnical Systems for Adaptation through Extensions of Cognitive Work Analysis.

    PubMed

    Naikar, Neelam; Elix, Ben

    2016-01-01

    This paper proposes an approach for integrated system design, which has the intent of facilitating high levels of effectiveness in sociotechnical systems by promoting their capacity for adaptation. Building on earlier ideas and empirical observations, this approach recognizes that to create adaptive systems it is necessary to integrate the design of all of the system elements, including the interfaces, teams, training, and automation, such that workers are supported in adapting their behavior as well as their structure, or organization, in a coherent manner. Current approaches for work analysis and design are limited in regard to this fundamental objective, especially in cases when workers are confronted with unforeseen events. A suitable starting point is offered by cognitive work analysis (CWA), but while this framework can support actors in adapting their behavior, it does not necessarily accommodate adaptations in their structure. Moreover, associated design approaches generally focus on individual system elements, and those that consider multiple elements appear limited in their ability to facilitate integration, especially in the manner intended here. The proposed approach puts forward the set of possibilities for work organization in a system as the central mechanism for binding the design of its various elements, so that actors can adapt their structure as well as their behavior-in a unified fashion-to handle both familiar and novel conditions. Accordingly, this paper demonstrates how the set of possibilities for work organization in a system may be demarcated independently of the situation, through extensions of CWA, and how it may be utilized in design. This lynchpin, conceptualized in the form of a diagram of work organization possibilities (WOP), is important for preserving a system's inherent capacity for adaptation. Future research should focus on validating these concepts and establishing the feasibility of implementing them in industrial contexts.

  15. Integrated System Design: Promoting the Capacity of Sociotechnical Systems for Adaptation through Extensions of Cognitive Work Analysis

    PubMed Central

    Naikar, Neelam; Elix, Ben

    2016-01-01

    This paper proposes an approach for integrated system design, which has the intent of facilitating high levels of effectiveness in sociotechnical systems by promoting their capacity for adaptation. Building on earlier ideas and empirical observations, this approach recognizes that to create adaptive systems it is necessary to integrate the design of all of the system elements, including the interfaces, teams, training, and automation, such that workers are supported in adapting their behavior as well as their structure, or organization, in a coherent manner. Current approaches for work analysis and design are limited in regard to this fundamental objective, especially in cases when workers are confronted with unforeseen events. A suitable starting point is offered by cognitive work analysis (CWA), but while this framework can support actors in adapting their behavior, it does not necessarily accommodate adaptations in their structure. Moreover, associated design approaches generally focus on individual system elements, and those that consider multiple elements appear limited in their ability to facilitate integration, especially in the manner intended here. The proposed approach puts forward the set of possibilities for work organization in a system as the central mechanism for binding the design of its various elements, so that actors can adapt their structure as well as their behavior—in a unified fashion—to handle both familiar and novel conditions. Accordingly, this paper demonstrates how the set of possibilities for work organization in a system may be demarcated independently of the situation, through extensions of CWA, and how it may be utilized in design. This lynchpin, conceptualized in the form of a diagram of work organization possibilities (WOP), is important for preserving a system's inherent capacity for adaptation. Future research should focus on validating these concepts and establishing the feasibility of implementing them in industrial

  16. Low sidelobe nonlinear stepped-frequency waveforms

    NASA Astrophysics Data System (ADS)

    Chebanov, Dmitry

    2008-04-01

    Frequency stepping is one of the known techniques employed by modern radars to attain high range resolution. One of the main advantages of this approach is that it allows to achieve wideband pulse compression through narrowband processing. It is also known that the traditional linear stepped-frequency waveform suffers from relatively high range sidelobes and grating lobes that appear due to periodicities in the Discrete Fourier Transform (DFT). An amplitude weighting (applied prior to the DFT) is typically used to reduce the near-in sidelobes. This results in undesirable losses in sensitivity. In this paper, we propose a new approach that may be used to derive families of nonlinear stepped-frequency waveforms that would have desired characteristics such as suppressed grating lobes and built-in low range sidelobes. Our approach is based on new analytical properties of stepped-frequency waveforms presented in the paper. We give examples of nonlinear waveforms generated by this approach and show that they exhibit improved performance when compared with traditional waveforms.

  17. Gaussian Decomposition of Laser Altimeter Waveforms

    NASA Technical Reports Server (NTRS)

    Hofton, Michelle A.; Minster, J. Bernard; Blair, J. Bryan

    1999-01-01

    We develop a method to decompose a laser altimeter return waveform into its Gaussian components assuming that the position of each Gaussian within the waveform can be used to calculate the mean elevation of a specific reflecting surface within the laser footprint. We estimate the number of Gaussian components from the number of inflection points of a smoothed copy of the laser waveform, and obtain initial estimates of the Gaussian half-widths and positions from the positions of its consecutive inflection points. Initial amplitude estimates are obtained using a non-negative least-squares method. To reduce the likelihood of fitting the background noise within the waveform and to minimize the number of Gaussians needed in the approximation, we rank the "importance" of each Gaussian in the decomposition using its initial half-width and amplitude estimates. The initial parameter estimates of all Gaussians ranked "important" are optimized using the Levenburg-Marquardt method. If the sum of the Gaussians does not approximate the return waveform to a prescribed accuracy, then additional Gaussians are included in the optimization procedure. The Gaussian decomposition method is demonstrated on data collected by the airborne Laser Vegetation Imaging Sensor (LVIS) in October 1997 over the Sequoia National Forest, California.

  18. Online learning control using adaptive critic designs with sparse kernel machines.

    PubMed

    Xu, Xin; Hou, Zhongsheng; Lian, Chuanqiang; He, Haibo

    2013-05-01

    In the past decade, adaptive critic designs (ACDs), including heuristic dynamic programming (HDP), dual heuristic programming (DHP), and their action-dependent ones, have been widely studied to realize online learning control of dynamical systems. However, because neural networks with manually designed features are commonly used to deal with continuous state and action spaces, the generalization capability and learning efficiency of previous ACDs still need to be improved. In this paper, a novel framework of ACDs with sparse kernel machines is presented by integrating kernel methods into the critic of ACDs. To improve the generalization capability as well as the computational efficiency of kernel machines, a sparsification method based on the approximately linear dependence analysis is used. Using the sparse kernel machines, two kernel-based ACD algorithms, that is, kernel HDP (KHDP) and kernel DHP (KDHP), are proposed and their performance is analyzed both theoretically and empirically. Because of the representation learning and generalization capability of sparse kernel machines, KHDP and KDHP can obtain much better performance than previous HDP and DHP with manually designed neural networks. Simulation and experimental results of two nonlinear control problems, that is, a continuous-action inverted pendulum problem and a ball and plate control problem, demonstrate the effectiveness of the proposed kernel ACD methods.

  19. Micro-Randomized Trials: An Experimental Design for Developing Just-in-Time Adaptive Interventions

    PubMed Central

    Klasnja, Predrag; Hekler, Eric B.; Shiffman, Saul; Boruvka, Audrey; Almirall, Daniel; Tewari, Ambuj; Murphy, Susan A.

    2015-01-01

    Objective This paper presents an experimental design, the micro-randomized trial, developed to support optimization of just-in-time adaptive interventions (JITAIs). JITAIs are mHealth technologies that aim to deliver the right intervention components at the right times and locations to optimally support individuals’ health behaviors. Micro-randomized trials offer a way to optimize such interventions by enabling modeling of causal effects and time-varying effect moderation for individual intervention components within a JITAI. Methods The paper describes the micro-randomized trial design, enumerates research questions that this experimental design can help answer, and provides an overview of the data analyses that can be used to assess the causal effects of studied intervention components and investigate time-varying moderation of those effects. Results Micro-randomized trials enable causal modeling of proximal effects of the randomized intervention components and assessment of time-varying moderation of those effects. Conclusions Micro-randomized trials can help researchers understand whether their interventions are having intended effects, when and for whom they are effective, and what factors moderate the interventions’ effects, enabling creation of more effective JITAIs. PMID:26651463

  20. Physical Constraints on Biological Integral Control Design for Homeostasis and Sensory Adaptation

    PubMed Central

    Ang, Jordan; McMillen, David R.

    2013-01-01

    Synthetic biology includes an effort to use design-based approaches to create novel controllers, biological systems aimed at regulating the output of other biological processes. The design of such controllers can be guided by results from control theory, including the strategy of integral feedback control, which is central to regulation, sensory adaptation, and long-term robustness. Realization of integral control in a synthetic network is an attractive prospect, but the nature of biochemical networks can make the implementation of even basic control structures challenging. Here we present a study of the general challenges and important constraints that will arise in efforts to engineer biological integral feedback controllers or to analyze existing natural systems. Constraints arise from the need to identify target output values that the combined process-plus-controller system can reach, and to ensure that the controller implements a good approximation of integral feedback control. These constraints depend on mild assumptions about the shape of input-output relationships in the biological components, and thus will apply to a variety of biochemical systems. We summarize our results as a set of variable constraints intended to provide guidance for the design or analysis of a working biological integral feedback controller. PMID:23442873

  1. Physical constraints on biological integral control design for homeostasis and sensory adaptation.

    PubMed

    Ang, Jordan; McMillen, David R

    2013-01-22

    Synthetic biology includes an effort to use design-based approaches to create novel controllers, biological systems aimed at regulating the output of other biological processes. The design of such controllers can be guided by results from control theory, including the strategy of integral feedback control, which is central to regulation, sensory adaptation, and long-term robustness. Realization of integral control in a synthetic network is an attractive prospect, but the nature of biochemical networks can make the implementation of even basic control structures challenging. Here we present a study of the general challenges and important constraints that will arise in efforts to engineer biological integral feedback controllers or to analyze existing natural systems. Constraints arise from the need to identify target output values that the combined process-plus-controller system can reach, and to ensure that the controller implements a good approximation of integral feedback control. These constraints depend on mild assumptions about the shape of input-output relationships in the biological components, and thus will apply to a variety of biochemical systems. We summarize our results as a set of variable constraints intended to provide guidance for the design or analysis of a working biological integral feedback controller.

  2. An implementable digital adaptive flight controller designed using stabilized single-stage algorithms

    NASA Technical Reports Server (NTRS)

    Alag, G.; Kaufman, H.

    1977-01-01

    An explicit adaptive controller, which makes direct use of on-line parameter identification, has been developed and applied to both the linearized and nonlinear equations of motion for the F-8 aircraft. This controller is composed of an on-line weighted least squares parameter identifier, a Kalman state filter, and a real model following control law designed using single-stage performance indices. The corresponding control gains are readily adjustable in accordance with parameter changes to ensure asymptotic stability if the conditions of perfect model following are satisfied, and stability in the sense of boundedness otherwise. Simulation experiments with realistic measurement noise indicate that the controller was effective in compensating for parameter variations and capable of rapid recovery from a set of erroneous initial parameter estimates which defined a set of destabilizing gains.

  3. CONFIG - Adapting qualitative modeling and discrete event simulation for design of fault management systems

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.; Basham, Bryan D.

    1989-01-01

    CONFIG is a modeling and simulation tool prototype for analyzing the normal and faulty qualitative behaviors of engineered systems. Qualitative modeling and discrete-event simulation have been adapted and integrated, to support early development, during system design, of software and procedures for management of failures, especially in diagnostic expert systems. Qualitative component models are defined in terms of normal and faulty modes and processes, which are defined by invocation statements and effect statements with time delays. System models are constructed graphically by using instances of components and relations from object-oriented hierarchical model libraries. Extension and reuse of CONFIG models and analysis capabilities in hybrid rule- and model-based expert fault-management support systems are discussed.

  4. Design of a nonlinear adaptive filter for suppression of shuttle pilot-induced oscillation tendencies

    NASA Technical Reports Server (NTRS)

    Smith, J. W.; Edwards, J. W.

    1980-01-01

    Analysis of a longitudinal pilot-induced oscillation (PIO) experienced just prior to touchdown on the final flight of the space shuttle's approach landing tests indicated that the source of the problem was a combination of poor basic handling qualities aggravated by time delays through the digital flight control computer and rate limiting of the elevator actuators due to high pilot gain. A nonlinear PIO suppression (PIOS) filter was designed and developed to alleviate the vehicle's PIO tendencies by reducing the gain in the command path. From analytical and simulator studies it was shown that the PIOS filter, in an adaptive fashion, can attenuate the command path gain without adding phase lag to the system. With the pitch attitude loop of a simulated shuttle model closed, the PIOS filter increased the gain margin by a factor of about two.

  5. Design of a shape adaptive airfoil actuated by a Shape Memory Alloy strip for airplane tail

    NASA Astrophysics Data System (ADS)

    Shirzadeh, R.; Raissi Charmacani, K.; Tabesh, M.

    2011-04-01

    Of the factors that mainly affect the efficiency of the wing during a special flow regime, the shape of its airfoil cross section is the most significant. Airfoils are generally designed for a specific flight condition and, therefore, are not fully optimized in all flight conditions. It is very desirable to have an airfoil with the ability to change its shape based on the current regime. Shape memory alloy (SMA) actuators activate in response to changes in the temperature and can recover their original configuration after being deformed. This study presents the development of a method to control the shape of an airfoil using SMA actuators. To predict the thermomechanical behaviors of an SMA thin strip, 3D incremental formulation of the SMA constitutive model is implemented in FEA software package ABAQUS. The interactions between the airfoil structure and SMA thin strip actuator are investigated. Also, the aerodynamic performance of a standard airfoil with a plain flap is compared with an adaptive airfoil.

  6. A subgroup cluster-based Bayesian adaptive design for precision medicine.

    PubMed

    Guo, Wentian; Ji, Yuan; Catenacci, Daniel V T

    2016-10-24

    In precision medicine, a patient is treated with targeted therapies that are predicted to be effective based on the patient's baseline characteristics such as biomarker profiles. Oftentimes, patient subgroups are unknown and must be learned through inference using observed data. We present SCUBA, a Subgroup ClUster-based Bayesian Adaptive design aiming to fulfill two simultaneous goals in a clinical trial, 1) to treatments enrich the allocation of each subgroup of patients to their precision and desirable treatments and 2) to report multiple subgroup-treatment pairs (STPs). Using random partitions and semiparametric Bayesian models, SCUBA provides coherent and probabilistic assessment of potential patient subgroups and their associated targeted therapies. Each STP can then be used for future confirmatory studies for regulatory approval. Through extensive simulation studies, we present an application of SCUBA to an innovative clinical trial in gastroesphogeal cancer.

  7. Adapting Rational Unified Process (RUP) approach in designing a secure e-Tendering model

    NASA Astrophysics Data System (ADS)

    Mohd, Haslina; Robie, Muhammad Afdhal Muhammad; Baharom, Fauziah; Darus, Norida Muhd; Saip, Mohamed Ali; Yasin, Azman

    2016-08-01

    e-Tendering is an electronic processing of the tender document via internet and allow tenderer to publish, communicate, access, receive and submit all tender related information and documentation via internet. This study aims to design the e-Tendering system using Rational Unified Process approach. RUP provides a disciplined approach on how to assign tasks and responsibilities within the software development process. RUP has four phases that can assist researchers to adjust the requirements of various projects with different scope, problem and the size of projects. RUP is characterized as a use case driven, architecture centered, iterative and incremental process model. However the scope of this study only focusing on Inception and Elaboration phases as step to develop the model and perform only three of nine workflows (business modeling, requirements, analysis and design). RUP has a strong focus on documents and the activities in the inception and elaboration phases mainly concern the creation of diagrams and writing of textual descriptions. The UML notation and the software program, Star UML are used to support the design of e-Tendering. The e-Tendering design based on the RUP approach can contribute to e-Tendering developers and researchers in e-Tendering domain. In addition, this study also shows that the RUP is one of the best system development methodology that can be used as one of the research methodology in Software Engineering domain related to secured design of any observed application. This methodology has been tested in various studies in certain domains, such as in Simulation-based Decision Support, Security Requirement Engineering, Business Modeling and Secure System Requirement, and so forth. As a conclusion, these studies showed that the RUP one of a good research methodology that can be adapted in any Software Engineering (SE) research domain that required a few artifacts to be generated such as use case modeling, misuse case modeling, activity

  8. Application of Adaptive Design Methodology in Development of a Long-Acting Glucagon-Like Peptide-1 Analog (Dulaglutide): Statistical Design and Simulations

    PubMed Central

    Skrivanek, Zachary; Berry, Scott; Berry, Don; Chien, Jenny; Geiger, Mary Jane; Anderson, James H.; Gaydos, Brenda

    2012-01-01

    Background Dulaglutide (dula, LY2189265), a long-acting glucagon-like peptide-1 analog, is being developed to treat type 2 diabetes mellitus. Methods To foster the development of dula, we designed a two-stage adaptive, dose-finding, inferentially seamless phase 2/3 study. The Bayesian theoretical framework is used to adaptively randomize patients in stage 1 to 7 dula doses and, at the decision point, to either stop for futility or to select up to 2 dula doses for stage 2. After dose selection, patients continue to be randomized to the selected dula doses or comparator arms. Data from patients assigned the selected doses will be pooled across both stages and analyzed with an analysis of covariance model, using baseline hemoglobin A1c and country as covariates. The operating characteristics of the trial were assessed by extensive simulation studies. Results Simulations demonstrated that the adaptive design would identify the correct doses 88% of the time, compared to as low as 6% for a fixed-dose design (the latter value based on frequentist decision rules analogous to the Bayesian decision rules for adaptive design). Conclusions This article discusses the decision rules used to select the dula dose(s); the mathematical details of the adaptive algorithm—including a description of the clinical utility index used to mathematically quantify the desirability of a dose based on safety and efficacy measurements; and a description of the simulation process and results that quantify the operating characteristics of the design. PMID:23294775

  9. Developing a Bayesian adaptive design for a phase I clinical trial: a case study for a novel HIV treatment.

    PubMed

    Mason, Alexina J; Gonzalez-Maffe, Juan; Quinn, Killian; Doyle, Nicki; Legg, Ken; Norsworthy, Peter; Trevelion, Roy; Winston, Alan; Ashby, Deborah

    2017-02-28

    The design of phase I studies is often challenging, because of limited evidence to inform study protocols. Adaptive designs are now well established in cancer but much less so in other clinical areas. A phase I study to assess the safety, pharmacokinetic profile and antiretroviral efficacy of C34-PEG4 -Chol, a novel peptide fusion inhibitor for the treatment of HIV infection, has been set up with Medical Research Council funding. During the study workup, Bayesian adaptive designs based on the continual reassessment method were compared with a more standard rule-based design, with the aim of choosing a design that would maximise the scientific information gained from the study. The process of specifying and evaluating the design options was time consuming and required the active involvement of all members of the trial's protocol development team. However, the effort was worthwhile as the originally proposed rule-based design has been replaced by a more efficient Bayesian adaptive design. While the outcome to be modelled, design details and evaluation criteria are trial specific, the principles behind their selection are general. This case study illustrates the steps required to establish a design in a novel context. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

    DTIC Science & Technology

    2008-09-01

    correlation coefficient (CC), or some comparable detection statistic, exceeds a given threshold. Since these methods exploit characteristic details of the...multiple channels since stacking can be performed on the correlation coefficient traces with a significant array-gain. A detected event that is co-located...with the master event will record the same time-difference at every site in an arbitrarily spaced network which means that the correlation coefficient traces

  11. (DURIP) MIMO Radar Testbed for Waveform Adaptive Sensing Research

    DTIC Science & Technology

    2015-06-17

    to implement image suppression and channel selection. Heterodyne receivers can achieve high sensitivity and channel selectivity, DC offset is...common to receivers with intermediate frequency conversion stages. However, significant DC offsets at the output of quadrature mixers as a result of LO...practice. In addition low-IF bandpass sampling system enables us to use a DC - blocker at the output of quadrature mixer output, eliminating the DC

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

    PubMed

    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.

  13. Photonic arbitrary waveform generator based on Taylor synthesis method.

    PubMed

    Liao, Shasha; Ding, Yunhong; Dong, Jianji; Yan, Siqi; Wang, Xu; Zhang, Xinliang

    2016-10-17

    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 dispersion, which are difficult to fabricate on chip. Our scheme is compact and capable for integration with electronics.

  14. Wavelet analysis of the impedance cardiogram waveforms

    NASA Astrophysics Data System (ADS)

    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.

  15. Krylov subspace acceleration of waveform relaxation

    SciTech Connect

    Lumsdaine, A.; Wu, Deyun

    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).

  16. Changing the waveform of circadian rhythms: considerations for shift-work.

    PubMed

    Harrison, Elizabeth M; Gorman, Michael R

    2012-01-01

    Circadian disruption in shift-work is common and has deleterious effects on health and performance. Current efforts to mitigate these harms reasonably focus on the phase of the circadian pacemaker, which unfortunately in humans, shifts slowly and often incompletely. Temporal reorganization of rhythmic waveform (i.e., the shape of its 24 h oscillation), rather than phase, however, may better match performance demands of shift-workers and can be quickly and feasibly implemented in animals. In fact, a bifurcated pacemaker waveform may permit stable entrainment of a bimodal sleep/wake rhythm promoting alertness in both night and daylight hours. Although bifurcation has yet to be formally assessed in humans, evidence of conserved properties of circadian organization and plasticity predict its occurrence: humans respond to conventional manipulations of waveform (e.g., photoperiodism); behaviorally, the sleep/wake rhythm is adaptable; and finally, the human circadian system likely derives from the same multiple cellular oscillators that permit waveform flexibility in the rodent pacemaker. In short, investigation into untried manipulations of waveform in humans to facilitate adjustment to challenging schedules is justified.

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

    PubMed

    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

  18. Direct Waveform Inversion: a New Recursive Scheme

    NASA Astrophysics Data System (ADS)

    Zheng, Y.

    2015-12-01

    The goal of the full-waveform inversion (FWI) is to find an Earth's model such that the synthetic waveforms computed using the model fit the observed ones. In practice, such a model is found in the context of the perturbation approach in an iterative fashion. Specifically, to find such a model, one starts from an initial global velocity model and perform model updating iteratively based on the Frechet derivative or single scattering by adjoint methods to minimize some cost function. However, this process often leads to local minima for the nonlinear cost function in the optimization and slow or no convergence when the starting model is far from the true model. To solve for the initial-model dependence and the convergence issue, we show a new direct waveform inversion (DWI) idea to directly invert the waveform data recursively by explicitly enforcing the causality principle. The DWI offers the advantage of assuming no global initial model and no iteration is needed for the model updating. Starting from the source-receiver region, the DWI builds the model outward recursively by fitting the earliest part of the reflection waveforms and the DWI process is always convergent. The DWI combines seismic imaging and velocity model building into one single process and this is in contrast to many industrial applications where seismic imaging/migration and velocity modeling building are done alternatively. The DWI idea is applicable to one-, two-, and three-dimensional spaces. We show numerical examples to support our idea using full waveform data including both free-surface and inter-bed multiples. Using reflection seismic data, we show that the DWI can invert for both velocity and density, separately.

  19. STEREO database of interplanetary Langmuir electric waveforms

    NASA Astrophysics Data System (ADS)

    Briand, C.; Henri, P.; Génot, V.; Lormant, N.; Dufourg, N.; Cecconi, B.; Nguyen, Q. N.; Goetz, K.

    2016-02-01

    This paper describes a database of electric waveforms that is available at the Centre de Données de la Physique des Plasmas (CDPP, http://cdpp.eu/). This database is specifically dedicated to waveforms of Langmuir/Z-mode waves. These waves occur in numerous kinetic processes involving electrons in space plasmas. Statistical analysis from a large data set of such waves is then of interest, e.g., to study the relaxation of high-velocity electron beams generated at interplanetary shock fronts, in current sheets and magnetic reconnection region, the transfer of energy between high and low frequencies, the generation of electromagnetic waves. The Langmuir waveforms were recorded by the Time Domain Sampler (TDS) of the WAVES radio instrument on board the STEREO mission. In this paper, we detail the criteria used to identify the Langmuir/Z-mode waves among the whole set of waveforms of the STEREO spacecraft. A database covering the November 2006 to August 2014 period is provided. It includes electric waveforms expressed in the normalized frame (B,B × Vsw,B × (B × Vsw)) with B and Vsw the local magnetic field and solar wind velocity vectors, and the local magnetic field in the variance frame, in an interval of ±1.5 min around the time of the Langmuir event. Quicklooks are also provided that display the three components of the electric waveforms together with the spectrum of E∥, together with the magnitude and components of the magnetic field in the 3 min interval, in the variance frame. Finally, the distribution of the Langmuir/Z-mode waves peak amplitude is also analyzed.

  20. Adaptive Flight Control Design with Optimal Control Modification on an F-18 Aircraft Model

    NASA Technical Reports Server (NTRS)

    Burken, John J.; Nguyen, Nhan T.; Griffin, Brian J.

    2010-01-01

    In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to as the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly; however, a large adaptive gain can lead to high-frequency oscillations which can adversely affect the robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient robustness. A damping term (v) is added in the modification to increase damping as needed. Simulations were conducted on a damaged F-18 aircraft (McDonnell Douglas, now The Boeing Company, Chicago, Illinois) with both the standard baseline dynamic inversion controller and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model.

  1. Adapting water treatment design and operations to the impacts of global climate change

    NASA Astrophysics Data System (ADS)

    Clark, Robert M.; Li, Zhiwei; Buchberger, Steven G.

    2011-12-01

    It is anticipated that global climate change will adversely impact source water quality in many areas of the United States and will therefore, potentially, impact the design and operation of current and future water treatment systems. The USEPA has initiated an effort called the Water Resources Adaptation Program (WRAP) which is intended to develop tools and techniques that can assess the impact of global climate change on urban drinking water and wastewater infrastructure. A three step approach for assessing climate change impacts on water treatment operation and design is being persude in this effort. The first step is the stochastic characterization of source water quality, the second step is the application of the USEPA Water Treatment Plant model and the third step is the application of cost algorithms to provide a metric that can be used to assess the coat impact of climate change. A model has been validated using data collected from Cincinnati's Richard Miller Water Treatment Plant for the USEPA Information Collection Rule (ICR) database. An analysis of the water treatment processes in response to assumed perturbations in raw water quality identified TOC, pH, and bromide as the three most important parameters affecting performance of the Miller WTP. The Miller Plant was simulated using the EPA WTP model to examine the impact of these parameters on selected regulated water quality parameters. Uncertainty in influent water quality was analyzed to estimate the risk of violating drinking water maximum contaminant levels (MCLs).Water quality changes in the Ohio River were projected for 2050 using Monte Carlo simulation and the WTP model was used to evaluate the effects of water quality changes on design and operation. Results indicate that the existing Miller WTP might not meet Safe Drinking Water Act MCL requirements for certain extreme future conditions. However, it was found that the risk of MCL violations under future conditions could be controlled by

  2. Tevatron anti-proton injection kicker waveform analysis

    SciTech Connect

    Hanna, B.; Finley, D.; /Fermilab

    1996-08-01

    This note describes the measurements of the waveform of the Tevatron antiproton injection kicker using the 150 Gev proton beam. This new horizontal kicker was installed at D48 during the summer of 1995 shutdown. These measurements were taken in two sessions [1] starting on October 10 and October 18, 1995. The measurements use the Tevatron BPM and flying wire systems. This note is a companion to the Tevatron proton injection kicker note published recently [2]. The design specifications for the kicker are given in Dinkel et al. [3].

  3. Human-Automation Interaction Design for Adaptive Cruise Control Systems of Ground Vehicles.

    PubMed

    Eom, Hwisoo; Lee, Sang Hun

    2015-06-12

    A majority of recently developed advanced vehicles have been equipped with various automated driver assistance systems, such as adaptive cruise control (ACC) and lane keeping assistance systems. ACC systems have several operational modes, and drivers can be unaware of the mode in which they are operating. Because mode confusion is a significant human error factor that contributes to traffic accidents, it is necessary to develop user interfaces for ACC systems that can reduce mode confusion. To meet this requirement, this paper presents a new human-automation interaction design methodology in which the compatibility of the machine and interface models is determined using the proposed criteria, and if the models are incompatible, one or both of the models is/are modified to make them compatible. To investigate the effectiveness of our methodology, we designed two new interfaces by separately modifying the machine model and the interface model and then performed driver-in-the-loop experiments. The results showed that modifying the machine model provides a more compact, acceptable, effective, and safe interface than modifying the interface model.

  4. Toward design of an environment-aware adaptive locomotion-mode-recognition system.

    PubMed

    Du, Lin; Zhang, Fan; Liu, Ming; Huang, He

    2012-10-01

    In this study, we aimed to improve the performance of a locomotion-mode-recognition system based on neuromuscular-mechanical fusion by introducing additional information about the walking environment. Linear-discriminant-analysis-based classifiers were first designed to identify a lower limb prosthesis user's locomotion mode based on electromyographic signals recorded from residual leg muscles and ground reaction forces measured from the prosthetic pylon. Nine transfemoral amputees who wore a passive hydraulic knee or powered prosthetic knee participated in this study. Information about the walking terrain was simulated and modeled as prior probability based on the principle of maximum entropy and integrated into the discriminant functions of the classifier. When the correct prior knowledge of walking terrain was simulated, the classification accuracy for each locomotion mode significantly increased and no task transitions were missed. In addition, simulated incorrect prior knowledge did not significantly reduce system performance, indicating that our design is robust against noisy and imperfect prior information. Furthermore, these observations were independent of the type of prosthesis applied. The promising results in this study may assist the further development of an environment-aware adaptive system for locomotion-mode recognition for powered lower limb prostheses or orthoses.

  5. Optical design considerations when imaging the fundus with an adaptive optics correction

    NASA Astrophysics Data System (ADS)

    Wang, Weiwei; Campbell, Melanie C. W.; Kisilak, Marsha L.; Boyd, Shelley R.

    2008-06-01

    Adaptive Optics (AO) technology has been used in confocal scanning laser ophthalmoscopes (CSLO) which are analogous to confocal scanning laser microscopes (CSLM) with advantages of real-time imaging, increased image contrast, a resistance to image degradation by scattered light, and improved optical sectioning. With AO, the instrumenteye system can have low enough aberrations for the optical quality to be limited primarily by diffraction. Diffraction-limited, high resolution imaging would be beneficial in the understanding and early detection of eye diseases such as diabetic retinopathy. However, to maintain diffraction-limited imaging, sufficient pixel sampling over the field of view is required, resulting in the need for increased data acquisition rates for larger fields. Imaging over smaller fields may be a disadvantage with clinical subjects because of fixation instability and the need to examine larger areas of the retina. Reduction in field size also reduces the amount of light sampled per pixel, increasing photon noise. For these reasons, we considered an instrument design with a larger field of view. When choosing scanners to be used in an AOCSLO, the ideal frame rate should be above the flicker fusion rate for the human observer and would also allow user control of targets projected onto the retina. In our AOCSLO design, we have studied the tradeoffs between field size, frame rate and factors affecting resolution. We will outline optical approaches to overcome some of these tradeoffs and still allow detection of the earliest changes in the fundus in diabetic retinopathy.

  6. Rational design and adaptive management of combination therapies for Hepatitis C virus infection

    SciTech Connect

    Ke, Ruian; Loverdo, Claude; Qi, Hangfei; Sun, Ren; Lloyd-Smith, James O.; Kouyos, Roger Dimitri

    2015-06-30

    Recent discoveries of direct acting antivirals against Hepatitis C virus (HCV) have raised hopes of effective treatment via combination therapies. Yet rapid evolution and high diversity of HCV populations, combined with the reality of suboptimal treatment adherence, make drug resistance a clinical and public health concern. We develop a general model incorporating viral dynamics and pharmacokinetics/ pharmacodynamics to assess how suboptimal adherence affects resistance development and clinical outcomes. We derive design principles and adaptive treatment strategies, identifying a high-risk period when missing doses is particularly risky for de novo resistance, and quantifying the number of additional doses needed to compensate when doses are missed. Using data from large-scale resistance assays, we demonstrate that the risk of resistance can be reduced substantially by applying these principles to a combination therapy of daclatasvir and asunaprevir. By providing a mechanistic framework to link patient characteristics to the risk of resistance, these findings show the potential of rational treatment design.

  7. Rational design and adaptive management of combination therapies for Hepatitis C virus infection

    DOE PAGES

    Ke, Ruian; Loverdo, Claude; Qi, Hangfei; ...

    2015-06-30

    Recent discoveries of direct acting antivirals against Hepatitis C virus (HCV) have raised hopes of effective treatment via combination therapies. Yet rapid evolution and high diversity of HCV populations, combined with the reality of suboptimal treatment adherence, make drug resistance a clinical and public health concern. We develop a general model incorporating viral dynamics and pharmacokinetics/ pharmacodynamics to assess how suboptimal adherence affects resistance development and clinical outcomes. We derive design principles and adaptive treatment strategies, identifying a high-risk period when missing doses is particularly risky for de novo resistance, and quantifying the number of additional doses needed to compensatemore » when doses are missed. Using data from large-scale resistance assays, we demonstrate that the risk of resistance can be reduced substantially by applying these principles to a combination therapy of daclatasvir and asunaprevir. By providing a mechanistic framework to link patient characteristics to the risk of resistance, these findings show the potential of rational treatment design.« less

  8. An adaptive design for updating the threshold value of a continuous biomarker

    PubMed Central

    Spencer, Amy V.; Harbron, Chris; Mander, Adrian; Wason, James; Peers, Ian

    2017-01-01

    Potential predictive biomarkers are often measured on a continuous scale, but in practice, a threshold value to divide the patient population into biomarker ‘positive’ and ‘negative’ is desirable. Early phase clinical trials are increasingly using biomarkers for patient selection, but at this stage, it is likely that little will be known about the relationship between the biomarker and the treatment outcome. We describe a single-arm trial design with adaptive enrichment, which can increase power to demonstrate efficacy within a patient subpopulation, the parameters of which are also estimated. Our design enables us to learn about the biomarker and optimally adjust the threshold during the study, using a combination of generalised linear modelling and Bayesian prediction. At the final analysis, a binomial exact test is carried out, allowing the hypothesis that ‘no population subset exists in which the novel treatment has a desirable response rate’ to be tested. Through extensive simulations, we are able to show increased power over fixed threshold methods in many situations without increasing the type-I error rate. We also show that estimates of the threshold, which defines the population subset, are unbiased and often more precise than those from fixed threshold studies. We provide an example of the method applied (retrospectively) to publically available data from a study of the use of tamoxifen after mastectomy by the German Breast Study Group, where progesterone receptor is the biomarker of interest. PMID:27417407

  9. Human-Automation Interaction Design for Adaptive Cruise Control Systems of Ground Vehicles

    PubMed Central

    Eom, Hwisoo; Lee, Sang Hun

    2015-01-01

    A majority of recently developed advanced vehicles have been equipped with various automated driver assistance systems, such as adaptive cruise control (ACC) and lane keeping assistance systems. ACC systems have several operational modes, and drivers can be unaware of the mode in which they are operating. Because mode confusion is a significant human error factor that contributes to traffic accidents, it is necessary to develop user interfaces for ACC systems that can reduce mode confusion. To meet this requirement, this paper presents a new human-automation interaction design methodology in which the compatibility of the machine and interface models is determined using the proposed criteria, and if the models are incompatible, one or both of the models is/are modified to make them compatible. To investigate the effectiveness of our methodology, we designed two new interfaces by separately modifying the machine model and the interface model and then performed driver-in-the-loop experiments. The results showed that modifying the machine model provides a more compact, acceptable, effective, and safe interface than modifying the interface model. PMID:26076406

  10. Adaptive Signal Recovery on Graphs via Harmonic Analysis for Experimental Design in Neuroimaging

    PubMed Central

    Kim, Won Hwa; Hwang, Seong Jae; Adluru, Nagesh; Johnson, Sterling C.; Singh, Vikas

    2016-01-01

    Consider an experimental design of a neuroimaging study, where we need to obtain p measurements for each participant in a setting where p′ (< p) are cheaper and easier to acquire while the remaining (p – p′) are expensive. For example, the p′ measurements may include demographics, cognitive scores or routinely offered imaging scans while the (p – p′) measurements may correspond to more expensive types of brain image scans with a higher participant burden. In this scenario, it seems reasonable to seek an “adaptive” design for data acquisition so as to minimize the cost of the study without compromising statistical power. We show how this problem can be solved via harmonic analysis of a band-limited graph whose vertices correspond to participants and our goal is to fully recover a multi-variate signal on the nodes, given the full set of cheaper features and a partial set of more expensive measurements. This is accomplished using an adaptive query strategy derived from probing the properties of the graph in the frequency space. To demonstrate the benefits that this framework can provide, we present experimental evaluations on two independent neuroimaging studies and show that our proposed method can reliably recover the true signal with only partial observations directly yielding substantial financial savings. PMID:27807594

  11. Understanding thermal adaptation of enzymes through the multistate rational design and stability prediction of 100 adenylate kinases.

    PubMed

    Howell, Stanley C; Inampudi, Krishna Kishore; Bean, Doyle P; Wilson, Corey J

    2014-02-04

    Careful balance between structural stability and flexibility is a hallmark of enzymatic function, and temperature can affect both properties. Canonical (fixed-backbone) enzyme design strategies currently do not consider the role of these properties. Herein, we describe the rational design of 100 temperature-adapted adenylate kinase enzymes using a multistate design strategy that incorporates the impact of conformational changes to backbone structure and stability, in addition to experimental analysis of thermostability and function. Comparison of the experimental temperature of maximum activity to the melting temperature across all 100 variants reveals a strong correlation between these two parameters. In turn, experimental stability data were used to produce accurate predictions of thermostability, providing the requisite complement for de novo temperature-adapted enzyme design. In principle, this level of design-based analysis can be applied to any protein, paving the way toward identifying and understanding the hallmarks of the thermodynamic and structural limits of function.

  12. Prescribed performance synchronization controller design of fractional-order chaotic systems: An adaptive neural network control approach

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Lv, Hui; Jiao, Dongxiu

    2017-03-01

    In this study, an adaptive neural network synchronization (NNS) approach, capable of guaranteeing prescribed performance (PP), is designed for non-identical fractional-order chaotic systems (FOCSs). For PP synchronization, we mean that the synchronization error converges to an arbitrary small region of the origin with convergence rate greater than some function given in advance. Neural networks are utilized to estimate unknown nonlinear functions in the closed-loop system. Based on the integer-order Lyapunov stability theorem, a fractional-order adaptive NNS controller is designed, and the PP can be guaranteed. Finally, simulation results are presented to confirm our results.

  13. Experimental Design and Primary Data Analysis Methods for Comparing Adaptive Interventions

    ERIC Educational Resources Information Center

    Nahum-Shani, Inbal; Qian, Min; Almirall, Daniel; Pelham, William E.; Gnagy, Beth; Fabiano, Gregory A.; Waxmonsky, James G.; Yu, Jihnhee; Murphy, Susan A.

    2012-01-01

    In recent years, research in the area of intervention development has been shifting from the traditional fixed-intervention approach to "adaptive interventions," which allow greater individualization and adaptation of intervention options (i.e., intervention type and/or dosage) over time. Adaptive interventions are operationalized via a sequence…

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    ) is in attention which is a technique to integrate large scale and complicated circuits. Lots of ASICs have been applied to high energy astrophysics. In this paper, we show our attempt to miniaturize the antennas impedances measurement system and Waveform Capture using the analogue ASIC. We design 8bits segment D/A converter that is implemented inside the waveform receiver ASIC chip. We improve input logic of the D/A converter to generate very weak signals accurately. The designed chip realizes the measurement of the antenna impedance as well as the waveform observation in the board size of business cards.

  15. Which uncertainty? Using expert elicitation and expected value of information to design an adaptive program

    USGS Publications Warehouse

    Runge, Michael C.; Converse, Sarah J.; Lyons, James E.

    2011-01-01

    Natural resource management is plagued with uncertainty of many kinds, but not all uncertainties are equally important to resolve. The promise of adaptive management is that learning in the short-term will improve management in the long-term; that promise is best kept if the focus of learning is on those uncertainties that most impede achievement of management objectives. In this context, an existing tool of decision analysis, the expected value of perfect information (EVPI), is particularly valuable in identifying the most important uncertainties. Expert elicitation can be used to develop preliminary predictions of management response under a series of hypotheses, as well as prior weights for those hypotheses, and the EVPI can be used to determine how much management could improve if uncertainty was resolved. These methods were applied to management of whooping cranes (Grus americana), an endangered migratory bird that is being reintroduced in several places in North America. The Eastern Migratory Population of whooping cranes had exhibited almost no successful reproduction through 2009. Several dozen hypotheses can be advanced to explain this failure, and many of them lead to very different management responses. An expert panel articulated the hypotheses, provided prior weights for them, developed potential management strategies, and made predictions about the response of the population to each strategy under each hypothesis. Multi-criteria decision analysis identified a preferred strategy in the face of uncertainty, and analysis of the expected value of information identified how informative each strategy could be. These results provide the foundation for design of an adaptive management program.

  16. Software defined radio based multi-carrier multi-function waveform for cognitive radio

    NASA Astrophysics Data System (ADS)

    Zhou, Ruolin; Li, Xue; Chakravarthy, Vasu; Wu, Zhiqiang

    2010-04-01

    In this paper, we demonstrate an adaptive multicarrier multi-function waveform generator for cognitive radio via software defined radio. Using a USRP (universal software radio peripheral) software defined radio boards and GNU radio software, we implement a multi-carrier waveform generator which can generate multi-function waveforms such as OFDM, NC-OFDM, MC-CDMA, NC-MC-CDMA, CI/MC-CDMA, NCCI/ MC-CDMA, TDCS for cognitive radio. Additionally, we demonstrate a portable overlay cognitive radio using this multicarrier multi-function waveform generator. This cognitive radio is capable of detecting primary users in real time and adaptively adjusting its transmission parameters to avoid interference to primary users. More importantly, this cognitive radio can take advantage of multiple spectrum holes by employing non-contiguous multi-carrier transmission technologies. Additionally, we demonstrate that when the primary user transmission changes, the cognitive radio dynamically adjusts its transmission accordingly. We also demonstrate seamless real time video transmission between two cognitive radio nodes, while avoiding interference from primary users and interference to primary users operating in the same spectrum.

  17. Hybrid feedback feedforward: An efficient design of adaptive neural network control.

    PubMed

    Pan, Yongping; Liu, Yiqi; Xu, Bin; Yu, Haoyong

    2016-04-01

    This paper presents an efficient hybrid feedback feedforward (HFF) adaptive approximation-based control (AAC) strategy for a class of uncertain Euler-Lagrange systems. The control structure includes a proportional-derivative (PD) control term in the feedback loop and a radial-basis-function (RBF) neural network (NN) in the feedforward loop, which mimics the human motor learning control mechanism. At the presence of discontinuous friction, a sigmoid-jump-function NN is incorporated to improve control performance. The major difference of the proposed HFF-AAC design from the traditional feedback AAC (FB-AAC) design is that only desired outputs, rather than both tracking errors and desired outputs, are applied as RBF-NN inputs. Yet, such a slight modification leads to several attractive properties of HFF-AAC, including the convenient choice of an approximation domain, the decrease of the number of RBF-NN inputs, and semiglobal practical asymptotic stability dominated by control gains. Compared with previous HFF-AAC approaches, the proposed approach possesses the following two distinctive features: (i) all above attractive properties are achieved by a much simpler control scheme; (ii) the bounds of plant uncertainties are not required to be known. Consequently, the proposed approach guarantees a minimum configuration of the control structure and a minimum requirement of plant knowledge for the AAC design, which leads to a sharp decrease of implementation cost in terms of hardware selection, algorithm realization and system debugging. Simulation results have demonstrated that the proposed HFF-AAC can perform as good as or even better than the traditional FB-AAC under much simpler control synthesis and much lower computational cost.

  18. Structures and Mechanisms Design Concepts for Adaptive Deployable Entry Placement Technology

    NASA Technical Reports Server (NTRS)

    Yount, Bryan C.; Arnold, James O.; Gage, Peter J.; Mockelman, Jeffrey; Venkatapathy, Ethiraj

    2012-01-01

    System studies have shown that large deployable aerodynamic decelerators such as the Adaptive Deployable Entry and Placement Technology (ADEPT) concept can revolutionize future robotic and human exploration missions involving atmospheric entry, descent and landing by significantly reducing the maximum heating rate, total heat load, and deceleration loads experienced by the spacecraft during entry [1-3]. ADEPT and the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) [4] share the approach of stowing the entry system in the shroud of the launch vehicle and deploying it to a much larger diameter prior to entry. The ADEPT concept provides a low ballistic coefficient for planetary entry by employing an umbrella-like deployable structure consisting of ribs, struts and a fabric cover that form an aerodynamic decelerator capable of undergoing hypersonic flight. The ADEPT "skin" is a 3-D woven carbon cloth that serves as a thermal protection system (TPS) and as a structural surface that transfers aerodynamic forces to the underlying ribs [5]. This paper focuses on design activities associated with integrating ADEPT components (cloth, ribs, struts and mechanisms) into a system that can function across all configurations and environments of a typical mission concept: stowed during launch, in-space deployment, entry, descent, parachute deployment and separation from the landing payload. The baseline structures and mechanisms were selected via trade studies conducted during the summer and fall of 2012. They are now being incorporated into the design of a ground test article (GTA) that will be fabricated in 2013. It will be used to evaluate retention of the stowed configuration in a launch environment, mechanism operation for release, deployment and locking, and static strength of the deployed decelerator. Of particular interest are the carbon cloth interfaces, underlying hot structure, (Advanced Carbon- Carbon ribs) and other structural components (nose cap, struts, and

  19. Evaluation of an Adaptive Game that Uses EEG Measures Validated during the Design Process as Inputs to a Biocybernetic Loop

    PubMed Central

    Ewing, Kate C.; Fairclough, Stephen H.; Gilleade, Kiel

    2016-01-01

    Biocybernetic adaptation is a form of physiological computing whereby real-time data streaming from the brain and body is used by a negative control loop to adapt the user interface. This article describes the development of an adaptive game system that is designed to maximize player engagement by utilizing changes in real-time electroencephalography (EEG) to adjust the level of game demand. The research consists of four main stages: (1) the development of a conceptual framework upon which to model the interaction between person and system; (2) the validation of the psychophysiological inference underpinning the loop; (3) the construction of a working prototype; and (4) an evaluation of the adaptive game. Two studies are reported. The first demonstrates the sensitivity of EEG power in the (frontal) theta and (parietal) alpha bands to changing levels of game demand. These variables were then reformulated within the working biocybernetic control loop designed to maximize player engagement. The second study evaluated the performance of an adaptive game of Tetris with respect to system behavior and user experience. Important issues for the design and evaluation of closed-loop interfaces are discussed. PMID:27242486

  20. Evaluation of an Adaptive Game that Uses EEG Measures Validated during the Design Process as Inputs to a Biocybernetic Loop.

    PubMed

    Ewing, Kate C; Fairclough, Stephen H; Gilleade, Kiel

    2016-01-01

    Biocybernetic adaptation is a form of physiological computing whereby real-time data streaming from the brain and body is used by a negative control loop to adapt the user interface. This article describes the development of an adaptive game system that is designed to maximize player engagement by utilizing changes in real-time electroencephalography (EEG) to adjust the level of game demand. The research consists of four main stages: (1) the development of a conceptual framework upon which to model the interaction between person and system; (2) the validation of the psychophysiological inference underpinning the loop; (3) the construction of a working prototype; and (4) an evaluation of the adaptive game. Two studies are reported. The first demonstrates the sensitivity of EEG power in the (frontal) theta and (parietal) alpha bands to changing levels of game demand. These variables were then reformulated within the working biocybernetic control loop designed to maximize player engagement. The second study evaluated the performance of an adaptive game of Tetris with respect to system behavior and user experience. Important issues for the design and evaluation of closed-loop interfaces are discussed.

  1. A transformer of closely spaced pulsed waveforms

    NASA Technical Reports Server (NTRS)

    Niedra, J.

    1970-01-01

    Passive circuit, using diodes, transistors, and magnetic cores, transforms the voltage of repetitive positive or negative pulses. It combines a pulse transformer with switching devices to effect a resonant flux reset and can transform various pulsed waveforms that have a nonzero average value and are relatively cosely spaced in time.

  2. Parameter Estimation using Numerical Merger Waveforms

    NASA Technical Reports Server (NTRS)

    Thorpe, J. I.; McWilliams, S.; Kelly, B.; Fahey, R.; Arnaud, K.; Baker, J.

    2008-01-01

    Results: Developed parameter estimation model integrating complete waveforms and improved instrumental models. Initial results for equal-mass non-spinning systems indicate moderate improvement in most parameters, significant improvement in some Near-term improvement: a) Improved statistics; b) T-channel; c) Larger parameter space coverage. Combination with other results: a) Higher harmonics; b) Spin precession; c) Instrumental effects.

  3. Processing Waveforms as Trees for Pattern Recognition.

    DTIC Science & Technology

    1986-05-01

    patterns (after Ganong (15]) 5.7 ECG Classification As in the previous example, waveforms were simulated with additive colored gaussian noise. In order to...Principles and Techniques- (AAPG Course Note Series 13), Amer. Assoc. Pet. Geol., Tulsa, OK,p. 86, (1984). [15] W. F. Ganong , Review of Medical Physiology. Lange, Los Altos, CA. pp. 393-408, (1973). /

  4. Matter effects on binary neutron star waveforms

    NASA Astrophysics Data System (ADS)

    Read, Jocelyn S.; Baiotti, Luca; Creighton, Jolien D. E.; Friedman, John L.; Giacomazzo, Bruno; Kyutoku, Koutarou; Markakis, Charalampos; Rezzolla, Luciano; Shibata, Masaru; Taniguchi, Keisuke

    2013-08-01

    Using an extended set of equations of state and a multiple-group multiple-code collaborative effort to generate waveforms, we improve numerical-relativity-based data-analysis estimates of the measurability of matter effects in neutron-star binaries. We vary two parameters of a parametrized piecewise-polytropic equation of state (EOS) to analyze the measurability of EOS properties, via a parameter Λ that characterizes the quadrupole deformability of an isolated neutron star. We find that, to within the accuracy of the simulations, the departure of the waveform from point-particle (or spinless double black-hole binary) inspiral increases monotonically with Λ and changes in the EOS that did not change Λ are not measurable. We estimate with two methods the minimal and expected measurability of Λ in second- and third-generation gravitational-wave detectors. The first estimate using numerical waveforms alone shows that two EOSs which vary in radius by 1.3 km are distinguishable in mergers at 100 Mpc. The second estimate relies on the construction of hybrid waveforms by matching to post-Newtonian inspiral and estimates that the same EOSs are distinguishable in mergers at 300 Mpc. We calculate systematic errors arising from numerical uncertainties and hybrid construction, and we estimate the frequency at which such effects would interfere with template-based searches.

  5. Waveform Selectivity at the Same Frequency

    PubMed Central

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J.; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F.

    2015-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071

  6. Manipulation of zebrafish’s orientation using artificial cilia in a microchannel with actively adaptive wall design

    PubMed Central

    Mani, Karthick; Chang Chien, Tsung-Chun; Panigrahi, Bivas; Chen, Chia-Yuan

    2016-01-01

    The zebrafish is a powerful genetic model organism especially in the biomedical chapter for new drug discovery and development. The genetic toolbox which this vertebrate possesses opens a new window to investigate the etiology of human diseases with a high degree genetic similarity. Still, the requirements of laborious and time-consuming of contemporary zebrafish processing assays limit the procedure in carrying out such genetic screen at high throughput. Here, a zebrafish control scheme was initiated which includes the design and validation of a microfluidic platform to significantly increase the throughput and performance of zebrafish larvae manipulation using the concept of artificial cilia actuation. A moving wall design was integrated into this microfluidic platform first time in literature to accommodate zebrafish inside the microchannel from 1 day post-fertilization (dpf) to 6 dpf and can be further extended to 9 dpf for axial orientation control in a rotational range between 0 to 25 degrees at the minimum step of 2-degree increment in a stepwise manner. This moving wall feature was performed through the deflection of shape memory alloy wire embedded inside the microchannel controlled by the electrical waveforms with high accuracy. PMID:27821862

  7. Manipulation of zebrafish’s orientation using artificial cilia in a microchannel with actively adaptive wall design

    NASA Astrophysics Data System (ADS)

    Mani, Karthick; Chang Chien, Tsung-Chun; Panigrahi, Bivas; Chen, Chia-Yuan

    2016-11-01

    The zebrafish is a powerful genetic model organism especially in the biomedical chapter for new drug discovery and development. The genetic toolbox which this vertebrate possesses opens a new window to investigate the etiology of human diseases with a high degree genetic similarity. Still, the requirements of laborious and time-consuming of contemporary zebrafish processing assays limit the procedure in carrying out such genetic screen at high throughput. Here, a zebrafish control scheme was initiated which includes the design and validation of a microfluidic platform to significantly increase the throughput and performance of zebrafish larvae manipulation using the concept of artificial cilia actuation. A moving wall design was integrated into this microfluidic platform first time in literature to accommodate zebrafish inside the microchannel from 1 day post-fertilization (dpf) to 6 dpf and can be further extended to 9 dpf for axial orientation control in a rotational range between 0 to 25 degrees at the minimum step of 2-degree increment in a stepwise manner. This moving wall feature was performed through the deflection of shape memory alloy wire embedded inside the microchannel controlled by the electrical waveforms with high accuracy.

  8. Waveform calibration strategies for a small-footprint laser scanner

    NASA Astrophysics Data System (ADS)

    Roncat, Andreas; Wagner, Wolfgang; Melzer, Thomas; Ullrich, Andreas

    2008-10-01

    Waveform calibration is a crucial task in the processing of full-waveform laser scanner data. In most cases, there is a non-linear relationship between the "raw" waveform data stored by the sensor system and the actual input power. However, to establish standardized methods for the post processing of waveform data, input data related linearly to the power input are required. For some commercially available systems, this problem is handled by using a look-up table (LUT) as a transfer function from the "raw" amplitude (stored by the sensor system) of the peaks of the waveforms to their actual amplitude. Since the transformation is only valid for the peaks of the waveform, the question arises how this transformation would perturbate the shape (i.e. position, width and amplitude) of a backscattered laser pulse if applied to the whole waveform. This paper discusses the effects of the use of such non-linear transfer functions on complex laser scanner waveforms.

  9. JTRS/SCA and Custom/SDR Waveform Comparison

    NASA Technical Reports Server (NTRS)

    Oldham, Daniel R.; Scardelletti, Maximilian C.

    2007-01-01

    This paper compares two waveform implementations generating the same RF signal using the same SDR development system. Both waveforms implement a satellite modem using QPSK modulation at 1M BPS data rates with one half rate convolutional encoding. Both waveforms are partitioned the same across the general purpose processor (GPP) and the field programmable gate array (FPGA). Both waveforms implement the same equivalent set of radio functions on the GPP and FPGA. The GPP implements the majority of the radio functions and the FPGA implements the final digital RF modulator stage. One waveform is implemented directly on the SDR development system and the second waveform is implemented using the JTRS/SCA model. This paper contrasts the amount of resources to implement both waveforms and demonstrates the importance of waveform partitioning across the SDR development system.

  10. Radar altimeter waveform modeled parameter recovery. [SEASAT-1 data

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Satellite-borne radar altimeters include waveform sampling gates providing point samples of the transmitted radar pulse after its scattering from the ocean's surface. Averages of the waveform sampler data can be fitted by varying parameters in a model mean return waveform. The theoretical waveform model used is described as well as a general iterative nonlinear least squares procedures used to obtain estimates of parameters characterizing the modeled waveform for SEASAT-1 data. The six waveform parameters recovered by the fitting procedure are: (1) amplitude; (2) time origin, or track point; (3) ocean surface rms roughness; (4) noise baseline; (5) ocean surface skewness; and (6) altitude or off-nadir angle. Additional practical processing considerations are addressed and FORTRAN source listing for subroutines used in the waveform fitting are included. While the description is for the Seasat-1 altimeter waveform data analysis, the work can easily be generalized and extended to other radar altimeter systems.

  11. Design guidelines for adapting scientific research articles: An example from an introductory level, interdisciplinary program on soft matter

    NASA Astrophysics Data System (ADS)

    Langbeheim, Elon; Safran, Samuel A.; Yerushalmi, Edit

    2013-01-01

    We present design guidelines for using Adapted Primary Literature (APL) as part of current interdisciplinary topics to introductory physics students. APL is a text genre that allows students to comprehend a scientific article, while maintaining the core features of the communication among scientists, thus representing an authentic scientific discourse. We describe the adaptation of a research paper by Nobel Laureate Paul Flory on phase equilibrium in polymer-solvent mixtures that was presented to high school students in a project-based unit on soft matter. The adaptation followed two design strategies: a) Making explicit the interplay between the theory and experiment. b) Re-structuring the text to map the theory onto the students' prior knowledge. Specifically, we map the theory of polymer-solvent systems onto a model for binary mixtures of small molecules of equal size that was already studied in class.

  12. A 6 kV arbitrary waveform generator for the Tevatron Electron Lens

    NASA Astrophysics Data System (ADS)

    Pfeffer, H.; Saewert, G.

    2011-11-01

    This paper reports on a 6 kV modulator built and installed at Fermilab to drive the electron gun anode for the Tevatron Electron Lens (TEL). The TEL was built with the intention of shifting the individual (anti)proton bunch tunes to even out the tune spread among all 36 bunches with the desire of improving Tevatron integrated luminosity. This modulator is essentially a 6 kV arbitrary waveform generator that enables the TEL to define the electron beam intensity on a bunch-by-bunch basis. A voltage waveform is constructed having a 7 μs duration that corresponds to the tune shift requirements of a 12-bunch (anti)proton beam pulse train. This waveform is played out for any one or all three bunch trains in the Tevatron. The programmed waveform voltages transition to different levels at time intervals corresponding to the 395 ns bunch spacing. Thus, complex voltage waveforms can be played out at a sustained rate of 143 kHz over the full 6 kV output range. This paper describes the novel design of the inductive adder topology employing five transformers. It describes the design aspects that minimize switching losses for this multi-kilovolt, high repetition rate and high duty factor application.

  13. A 6 kV arbitrary waveform generator for the Tevatron Electron Lens

    DOE PAGES

    Pfeffer, H.; Saewert, G.

    2011-11-09

    This paper reports on a 6 kV modulator built and installed at Fermilab to drive the electron gun anode for the Tevatron Electron Lens (TEL). The TEL was built with the intention of shifting the individual (anti)proton bunch tunes to even out the tune spread among all 36 bunches with the desire of improving Tevatron integrated luminosity. This modulator is essentially a 6 kV arbitrary waveform generator that enables the TEL to define the electron beam intensity on a bunch-by-bunch basis. A voltage waveform is constructed having a 7 μs duration that corresponds to the tune shift requirements of amore » 12-bunch (anti)proton beam pulse train. This waveform is played out for any one or all three bunch trains in the Tevatron. The programmed waveform voltages transition to different levels at time intervals corresponding to the 395 ns bunch spacing. In addition, complex voltage waveforms can be played out at a sustained rate of 143 kHz over the full 6 kV output range. This paper describes the novel design of the inductive adder topology employing five transformers. It describes the design aspects that minimize switching losses for this multi-kilovolt, high repetition rate and high duty factor application.« less

  14. A 6 kV arbitrary waveform generator for the Tevatron Electron Lens

    SciTech Connect

    Pfeffer, H.; Saewert, G.

    2011-11-09

    This paper reports on a 6 kV modulator built and installed at Fermilab to drive the electron gun anode for the Tevatron Electron Lens (TEL). The TEL was built with the intention of shifting the individual (anti)proton bunch tunes to even out the tune spread among all 36 bunches with the desire of improving Tevatron integrated luminosity. This modulator is essentially a 6 kV arbitrary waveform generator that enables the TEL to define the electron beam intensity on a bunch-by-bunch basis. A voltage waveform is constructed having a 7 μs duration that corresponds to the tune shift requirements of a 12-bunch (anti)proton beam pulse train. This waveform is played out for any one or all three bunch trains in the Tevatron. The programmed waveform voltages transition to different levels at time intervals corresponding to the 395 ns bunch spacing. In addition, complex voltage waveforms can be played out at a sustained rate of 143 kHz over the full 6 kV output range. This paper describes the novel design of the inductive adder topology employing five transformers. It describes the design aspects that minimize switching losses for this multi-kilovolt, high repetition rate and high duty factor application.

  15. Design of an Adaptive Power Regulation Mechanism and a Nozzle for a Hydroelectric Power Plant Turbine Test Rig

    NASA Astrophysics Data System (ADS)

    Mert, Burak; Aytac, Zeynep; Tascioglu, Yigit; Celebioglu, Kutay; Aradag, Selin; ETU Hydro Research Center Team

    2014-11-01

    This study deals with the design of a power regulation mechanism for a Hydroelectric Power Plant (HEPP) model turbine test system which is designed to test Francis type hydroturbines up to 2 MW power with varying head and flow(discharge) values. Unlike the tailor made regulation mechanisms of full-sized, functional HEPPs; the design for the test system must be easily adapted to various turbines that are to be tested. In order to achieve this adaptability, a dynamic simulation model is constructed in MATLAB/Simulink SimMechanics. This model acquires geometric data and hydraulic loading data of the regulation system from Autodesk Inventor CAD models and Computational Fluid Dynamics (CFD) analysis respectively. The dynamic model is explained and case studies of two different HEPPs are performed for validation. CFD aided design of the turbine guide vanes, which is used as input for the dynamic model, is also presented. This research is financially supported by Turkish Ministry of Development.

  16. Pathology and failure in the design and implementation of adaptive management

    USGS Publications Warehouse

    Allen, Craig R.; Gunderson, Lance H.

    2011-01-01

    The conceptual underpinnings for adaptive management are simple; there will always be inherent uncertainty and unpredictability in the dynamics and behavior of complex ecological systems as a result non-linear interactions among components and emergence, yet management decisions must still be made. The strength of adaptive management is in the recognition and confrontation of such uncertainty. Rather than ignore uncertainty, or use it to preclude management actions, adaptive management can foster resilience and flexibility to cope with an uncertain future, and develop safe to fail management approaches that acknowledge inevitable changes and surprises. Since its initial introduction, adaptive management has been hailed as a solution to endless trial and error approaches to complex natural resource management challenges. However, its implementation has failed more often than not. It does not produce easy answers, and it is appropriate in only a subset of natural resource management problems. Clearly adaptive management has great potential when applied appropriately. Just as clearly adaptive management has seemingly failed to live up to its high expectations. Why? We outline nine pathologies and challenges that can lead to failure in adaptive management programs. We focus on general sources of failures in adaptive management, so that others can avoid these pitfalls in the future. Adaptive management can be a powerful and beneficial tool when applied correctly to appropriate management problems; the challenge is to keep the concept of adaptive management from being hijacked for inappropriate use.

  17. SAR processing with non-linear FM chirp waveforms.

    SciTech Connect

    Doerry, Armin Walter

    2006-12-01

    Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.

  18. Item Selection in Computerized Adaptive Testing: Improving the a-Stratified Design with the Sympson-Hetter Algorithm

    ERIC Educational Resources Information Center

    Leung, Chi-Keung; Chang, Hua-Hua; Hau, Kit-Tai

    2002-01-01

    Item exposure control, test-overlap minimization, and the efficient use of item pool are some of the important issues in computerized adaptive testing (CAT) designs. The overexposure of some items and high test-overlap rate may cause both item and test security problems. Previously these problems associated with the maximum information (Max-I)…

  19. Guiding Learners through Technology-Based Instruction: The Effects of Adaptive Guidance Design and Individual Differences on Learning over Time

    ERIC Educational Resources Information Center

    Kanar, Adam M.; Bell, Bradford S.

    2013-01-01

    Adaptive guidance is an instructional intervention that helps learners to make use of the control inherent in technology-based instruction. The present research investigated the interactive effects of guidance design (i.e., framing of guidance information) and individual differences (i.e., pretraining motivation and ability) on learning basic and…

  20. Adapting Evidence-Based Pedagogy to Local Cultural Contexts: A Design Research Study of Policy Borrowing in Vietnam

    ERIC Educational Resources Information Center

    Pham, Thanh Thi Hong; Renshaw, Peter

    2015-01-01

    This study employs design-based research to investigate how university teachers and their students from Vietnam perceived and adapted an evidence-based pedagogy known as "student-teams achievement division" (STAD). Two hundred and twenty one students and their teachers from three classes at a Vietnamese university participated in this…

  1. Optimization of reactor network design problem using Jumping Gene Adaptation of Differential Evolution

    NASA Astrophysics Data System (ADS)

    Gujarathi, Ashish M.; Purohit, S.; Srikanth, B.

    2015-06-01

    Detailed working principle of jumping gene adaptation of differential evolution (DE-JGa) is presented. The performance of the DE-JGa algorithm is compared with the performance of differential evolution (DE) and modified DE (MDE) by applying these algorithms on industrial problems. In this study Reactor network design (RND) problem is solved using DE, MDE, and DE-JGa algorithms: These industrial processes are highly nonlinear and complex with reference to optimal operating conditions with many equality and inequality constraints. Extensive computational comparisons have been made for all the chemical engineering problems considered. The results obtained in the present study show that DE-JGa algorithm outperforms the other algorithms (DE and MDE). Several comparisons are made among the algorithms with regard to the number of function evaluations (NFE)/CPU- time required to find the global optimum. The standard deviation and the variance values obtained using DE-JGa, DE and MDE algorithms also show that the DE-JGa algorithm gives consistent set of results for the majority of the test problems and the industrial real world problems.

  2. Adaptation of the quality by design concept in early pharmaceutical development of an intranasal nanosized formulation.

    PubMed

    Pallagi, Edina; Ambrus, Rita; Szabó-Révész, Piroska; Csóka, Ildikó

    2015-08-01

    Regulatory science based pharmaceutical development and product manufacturing is highly recommended by the authorities nowadays. The aim of this study was to adapt regulatory science even in the nano-pharmaceutical early development. Authors applied the quality by design (QbD) concept in the early development phase of nano-systems, where the illustration material was meloxicam. The meloxicam nanoparticles produced by co-grinding method for nasal administration were studied according to the QbD policy and the QbD based risk assessment (RA) was performed. The steps were implemented according to the relevant regulatory guidelines (quality target product profile (QTPP) determination, selection of critical quality attributes (CQAs) and critical process parameters (CPPs)) and a special software (Lean QbD Software(®)) was used for the RA, which represents a novelty in this field. The RA was able to predict and identify theoretically the factors (e.g. sample composition, production method parameters, etc.) which have the highest impact on the desired meloxicam-product quality. The results of the practical research justified the theoretical prediction. This method can improve pharmaceutical nano-developments by achieving shorter development time, lower cost, saving human resource efforts and more effective target-orientation. It makes possible focusing the resources on the selected parameters and area during the practical product development.

  3. Adaption of G-TAG Software for Validating Touch and Go Asteroid Sample Return Design Methodology

    NASA Technical Reports Server (NTRS)

    Blackmore, Lars James C.; Acikmese, Behcet; Mandic, Milan

    2012-01-01

    A software tool is used to demonstrate the feasibility of Touch and Go (TAG) sampling for Asteroid Sample Return missions. TAG is a concept whereby a spacecraft is in contact with the surface of a small body, such as a comet or asteroid, for a few seconds or less before ascending to a safe location away from the small body. Previous work at JPL developed the G-TAG simulation tool, which provides a software environment for fast, multi-body simulations of the TAG event. G-TAG is described in Multibody Simulation Software Testbed for Small-Body Exploration and Sampling, (NPO-47196) NASA Tech Briefs, Vol. 35, No. 11 (November 2011), p.54. This current innovation adapts this tool to a mission that intends to return a sample from the surface of an asteroid. In order to demonstrate the feasibility of the TAG concept, the new software tool was used to generate extensive simulations that demonstrate the designed spacecraft meets key requirements. These requirements state that contact force and duration must be sufficient to ensure that enough material from the surface is collected in the brushwheel sampler (BWS), and that the spacecraft must survive the contact and must be able to recover and ascend to a safe position, and maintain velocity and orientation after the contact.

  4. Design of a Compact, Bimorph Deformable Mirror-Based Adaptive Optics Scanning Laser Ophthalmoscope.

    PubMed

    He, Yi; Deng, Guohua; Wei, Ling; Li, Xiqi; Yang, Jinsheng; Shi, Guohua; Zhang, Yudong

    2016-01-01

    We have designed, constructed and tested an adaptive optics scanning laser ophthalmoscope (AOSLO) using a bimorph mirror. The simulated AOSLO system achieves diffraction-limited criterion through all the raster scanning fields (6.4 mm pupil, 3° × 3° on pupil). The bimorph mirror-based AOSLO corrected ocular aberrations in model eyes to less than 0.1 μm RMS wavefront error with a closed-loop bandwidth of a few Hz. Facilitated with a bimorph mirror at a stroke of ±15 μm with 35 elements and an aperture of 20 mm, the new AOSLO system has a size only half that of the first-generation AOSLO system. The significant increase in stroke allows for large ocular aberrations such as defocus in the range of ±600° and astigmatism in the range of ±200°, thereby fully exploiting the AO correcting capabilities for diseased human eyes in the future.

  5. Design and analysis of self-adapted task scheduling strategies in wireless sensor networks.

    PubMed

    Guo, Wenzhong; Xiong, Naixue; Chao, Han-Chieh; Hussain, Sajid; Chen, Guolong

    2011-01-01

    In a wireless sensor network (WSN), the usage of resources is usually highly related to the execution of tasks which consume a certain amount of computing and communication bandwidth. Parallel processing among sensors is a promising solution to provide the demanded computation capacity in WSNs. Task allocation and scheduling is a typical problem in the area of high performance computing. Although task allocation and scheduling in wired processor networks has been well studied in the past, their counterparts for WSNs remain largely unexplored. Existing traditional high performance computing solutions cannot be directly implemented in WSNs due to the limitations of WSNs such as limited resource availability and the shared communication medium. In this paper, a self-adapted task scheduling strategy for WSNs is presented. First, a multi-agent-based architecture for WSNs is proposed and a mathematical model of dynamic alliance is constructed for the task allocation problem. Then an effective discrete particle swarm optimization (PSO) algorithm for the dynamic alliance (DPSO-DA) with a well-designed particle position code and fitness function is proposed. A mutation operator which can effectively improve the algorithm's ability of global search and population diversity is also introduced in this algorithm. Finally, the simulation results show that the proposed solution can achieve significant better performance than other algorithms.

  6. Continuous-waveform constant-current isolated physiological stimulator

    PubMed Central

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

    2012-01-01

    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. PMID:22559554

  7. Continuous-waveform constant-current isolated physiological stimulator

    NASA Astrophysics Data System (ADS)

    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.

  8. Precisely synchronous and cascadable multi-channel arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Tian, Shulin; Guo, Guangkun; Xiao, Yindong

    2017-03-01

    The output bandwidth and the capability to generate multiple analog outputs with accurately adjustable relative phase are important specifications of arbitrary waveform generator (AWG). To increase the output bandwidth, AWG with a multi-memory paralleled direct digital synthesizer structure (DDS) was proposed to break through operating speed limitations of memory and field programmable gate array. But this structure does complicate synchronization of the analog outputs. This paper proposes a structure for synchronization of the outputs of multi-channel high speed AWG that generates arbitrary waveforms using a multi-memory paralleled DDS. Careful distribution of the clock and trigger signals enables elimination of the random initial phase caused by the frequency divider. Based on this structure, a four-channel 600 mega samples per second AWG is designed. An embedded clock synchronization calibration module is designed to eliminate the random phase difference caused by a frequency divider inside a digital-to-analog converter. The AWG provides a 240 MHz bandwidth, 16 mega-samples storage depth, inter-channel initial skew accuracy less than 150 ps, and 0.0001° phase resolution, which can be used to generate two pairs of I/Q signals or a pair of differential I/Q signals for the quadrature modulator. Additionally, more AWGs can be cascaded to obtain more output channels with an output timing skew between adjacent channels of less than 1.6 ns.

  9. Precisely synchronous and cascadable multi-channel arbitrary waveform generator.

    PubMed

    Liu, Ke; Tian, Shulin; Guo, Guangkun; Xiao, Yindong

    2017-03-01

    The output bandwidth and the capability to generate multiple analog outputs with accurately adjustable relative phase are important specifications of arbitrary waveform generator (AWG). To increase the output bandwidth, AWG with a multi-memory paralleled direct digital synthesizer structure (DDS) was proposed to break through operating speed limitations of memory and field programmable gate array. But this structure does complicate synchronization of the analog outputs. This paper proposes a structure for synchronization of the outputs of multi-channel high speed AWG that generates arbitrary waveforms using a multi-memory paralleled DDS. Careful distribution of the clock and trigger signals enables elimination of the random initial phase caused by the frequency divider. Based on this structure, a four-channel 600 mega samples per second AWG is designed. An embedded clock synchronization calibration module is designed to eliminate the random phase difference caused by a frequency divider inside a digital-to-analog converter. The AWG provides a 240 MHz bandwidth, 16 mega-samples storage depth, inter-channel initial skew accuracy less than 150 ps, and 0.0001° phase resolution, which can be used to generate two pairs of I/Q signals or a pair of differential I/Q signals for the quadrature modulator. Additionally, more AWGs can be cascaded to obtain more output channels with an output timing skew between adjacent channels of less than 1.6 ns.

  10. L(sub 1) Adaptive Control Design for NASA AirSTAR Flight Test Vehicle

    NASA Technical Reports Server (NTRS)

    Gregory, Irene M.; Cao, Chengyu; Hovakimyan, Naira; Zou, Xiaotian

    2009-01-01

    In this paper we present a new L(sub 1) adaptive control architecture that directly compensates for matched as well as unmatched system uncertainty. To evaluate the L(sub 1) adaptive controller, we take advantage of the flexible research environment with rapid prototyping and testing of control laws in the Airborne Subscale Transport Aircraft Research system at the NASA Langley Research Center. We apply the L(sub 1) adaptive control laws to the subscale turbine powered Generic Transport Model. The presented results are from a full nonlinear simulation of the Generic Transport Model and some preliminary pilot evaluations of the L(sub 1) adaptive control law.

  11. Control and Plasticity of the Presynaptic Action Potential Waveform at Small CNS Nerve Terminals

    PubMed Central

    Hoppa, Michael B.; Gouzer, Geraldine; Armbruster, Moritz; Ryan, Timothy A.

    2014-01-01

    SUMMARY The steep dependence of exocytosis on Ca2+ entry at nerve terminals implies that voltage control of both Ca2+ channel opening and the driving force for Ca2+ entry are powerful levers in sculpting synaptic efficacy. Using fast, genetically encoded voltage indicators in dissociated primary neurons, we show that at small nerve terminals K+ channels constrain the peak voltage of the presynaptic action potential (APSYN) to values much lower than those at cell somas. This key APSYN property additionally shows adaptive plasticity: manipulations that increase presynaptic Ca2+ channel abundance and release probability result in a commensurate lowering of the APSYN peak and narrowing of the waveform, while manipulations that decrease presynaptic Ca2+ channel abundance do the opposite. This modulation is eliminated upon blockade of Kv3.1 and Kv1 channels. Our studies thus reveal that adaptive plasticity in the APSYN waveform serves as an important regulator of synaptic function. PMID:25447742

  12. Friction Stir Weld Application and Tooling Design for the Multi-purpose Crew Vehicle Stage Adapter

    NASA Technical Reports Server (NTRS)

    Alcorn, John

    2013-01-01

    The Multi-Purpose Crew Vehicle (MPCV), commonly known as the Orion capsule, is planned to be the United States' next manned spacecraft for missions beyond low earth orbit. Following the cancellation of the Constellation program and creation of SLS (Space Launch System), the need arose for the MPCV to utilize the Delta IV Heavy rocket for a test launch scheduled for 2014 instead of the previously planned Ares I rocket. As a result, an adapter (MSA) must be used in conjunction with the MPCV to account for the variation in diameter of the launch vehicles; 5.5 meters down to 5.0 meters. Prior to ight article fabrication, a path nder (test article) will be fabricated to ne tune the associated manufacturing processes. The adapter will be comprised of an aluminum frustum (partial cone) that employs isogrid technology and circumferential rings on each end. The frustum will be fabricated by friction stir welding (FSW) three individual panels together on a Vertical Weld Tool (VWT) at NASA Marshall Space Flight Center. Subsequently, each circumferential ring will be friction stir welded to the frustum using a Robotic Weld Tool (RWT). The irregular geometry and large mass of the MSA require that extensive tooling preparation be put into support structures for the friction stir weld. The tooling on the VWT will be comprised of a set of conveyors mounted on pre-existing stanchions so that the MSA will have the ability to be rotated after each of the three friction stir welds. The tooling requirements to friction stir weld the rings with the RWT are somewhat more demanding. To support the mass of the MSA and resist the load of the weld tool, a system of mandrels will be mounted to stanchions and assembled in a circle. The goal of the paper will be to explain the design, fabrication, and assembly of the tooling, to explain the use of friction stir welding on the MSA path nder, and also to discuss the lessons learned and modi cations made in preparation for ight article fabrication

  13. Designing monitoring programs in an adaptive management context for regional multiple species conservation plans

    USGS Publications Warehouse

    Atkinson, A.J.; Trenham, P.C.; Fisher, R.N.; Hathaway, S.A.; Johnson, B.S.; Torres, S.G.; Moore, Y.C.

    2004-01-01

    critical management uncertainties; and 3) implementing long-term monitoring and adaptive management. Ultimately, the success of regional conservation planning depends on the ability of monitoring programs to confront the challenges of adaptively managing and monitoring complex ecosystems and diverse arrays of sensitive species.

  14. Adaptation and Communicative Design: Patterns of Interaction in Truthful and Deceptive Conversations.

    ERIC Educational Resources Information Center

    White, Cindy H.; Burgoon, Judee K.

    2001-01-01

    Derives hypotheses concerning patterns of interaction that occur across time in truthful and deceptive conversations among undergraduate students. Examines the nature of adaptability and mutual influence in interaction, interpersonal deception theory and interaction adaptation theory. Finds that deceivers felt more anxious and were more concerned…

  15. Designing an Adaptive Web-Based Learning System Based on Students' Cognitive Styles Identified Online

    ERIC Educational Resources Information Center

    Lo, Jia-Jiunn; Chan, Ya-Chen; Yeh, Shiou-Wen

    2012-01-01

    This study developed an adaptive web-based learning system focusing on students' cognitive styles. The system is composed of a student model and an adaptation model. It collected students' browsing behaviors to update the student model for unobtrusively identifying student cognitive styles through a multi-layer feed-forward neural network (MLFF).…

  16. Designing a Semantic Bliki System to Support Different Types of Knowledge and Adaptive Learning

    ERIC Educational Resources Information Center

    Huang, Shiu-Li; Yang, Chia-Wei

    2009-01-01

    Though blogs and wikis have been used to support knowledge management and e-learning, existing blogs and wikis cannot support different types of knowledge and adaptive learning. A case in point, types of knowledge vary greatly in category and viewpoints. Additionally, adaptive learning is crucial to improving one's learning performance. This study…

  17. Optical design for the Narrow Field InfraRed Adaptive Optics System (NFIRAOS) Petite on the Thirty Meter Telescope

    SciTech Connect

    Bauman, B; Gavel, D; Dekany, R; Ellerbroek, B

    2005-08-02

    We describe an exploratory optical design for the Narrow Field InfraRed Adaptive Optics (AO) System (NFIRAOS) Petite, a proposed adaptive optics system for the Thirty Meter Telescope Project. NFIRAOS will feed infrared spectrograph and wide-field imaging instruments with a diffraction limited beam. The adaptive optics system will require multi-guidestar tomographic wavefront sensing and multi-conjugate AO correction. The NFIRAOS Petite design specifications include two small 60 mm diameter deformable mirrors (DM's) used in a woofer/tweeter or multiconjugate arrangement. At least one DM would be a micro-electromechanical system (MEMS) DM. The AO system would correct a 10 to 30 arcsec diameter science field as well as laser guide stars (LGS's) located within a 60 arcsec diameter field and low-order or tip/tilt natural guide stars (NGS's) within a 60 arcsec diameter field. The WFS's are located downstream of the DM's so that they can be operated in true closed-loop, which is not necessarily a given in extremely large telescope adaptive optics design. The WFS's include adjustable corrector elements which correct the static aberrations of the AO relay due to field position and LGS distance height.

  18. Issues in the design and optimization of adaptive optics and laser guide stars for the Keck Telescopes

    SciTech Connect

    Max, C.E.; Gavel, D.T.; Olivier, S.S.

    1994-03-01

    We discuss issues in optimizing the design of adaptive optics and laser guide star systems for the Keck Telescope. The initial tip-tilt system will use Keck`s chopping secondary mirror. We describe design constraints, choice of detector, and expected performance of this tip-tilt system as well as its sky coverage. The adaptive optics system is being optimized for wavelengths of I-2.2{mu}m. We are studying adaptive optics concepts which use a wavefront sensor with varying numbers of subapertures, so as to respond to changing turbulence conditions. The goal is to be able to ``gang together`` groups of deformable mirror subapertures under software control, when conditions call for larger subapertures. We present performance predictions as a function of sky coverage and the number of deformable mirror degrees of freedom. We analyze the predicted brightness several candidate laser guide star systems, as a function of laser power and pulse format. These predictions are used to examine the resulting Strehl as a function of observing wavelength and laser type. We discuss laser waste heat and thermal management issues, and conclude with an overview of instruments under design to take advantage of the Keck adaptive optics system.

  19. Point estimation and p-values in phase II adaptive two-stage designs with a binary endpoint.

    PubMed

    Kunzmann, K; Kieser, M

    2017-03-15

    Clinical trials in phase II of drug development are frequently conducted as single-arm two-stage studies with a binary endpoint. Recently, adaptive designs have been proposed for this setting that enable a midcourse modification of the sample size. While these designs are elaborated with respect to hypothesis testing by assuring control of the type I error rate, the topic of point estimation has up to now not been addressed. For adaptive designs with a prespecified sample size recalculation rule, we propose a new point estimator that both assures compatibility of estimation and test decision and minimizes average mean squared error. This estimator can be interpreted as a constrained posterior mean estimate based on the non-informative Jeffreys prior. A comparative investigation of the operating characteristics demonstrates the favorable properties of the proposed approach. Copyright © 2016 John Wiley & Sons, Ltd.

  20. A Phase I/II adaptive design for heterogeneous groups with application to a stereotactic body radiation therapy trial.

    PubMed

    Wages, Nolan A; Read, Paul W; Petroni, Gina R

    2015-01-01

    Dose-finding studies that aim to evaluate the safety of single agents are becoming less common, and advances in clinical research have complicated the paradigm of dose finding in oncology. A class of more complex problems, such as targeted agents, combination therapies and stratification of patients by clinical or genetic characteristics, has created the need to adapt early-phase trial design to the specific type of drug being investigated and the corresponding endpoints. In this article, we describe the implementation of an adaptive design based on a continual reassessment method for heterogeneous groups, modified to coincide with the objectives of a Phase I/II trial of stereotactic body radiation therapy in patients with painful osseous metastatic disease. Operating characteristics of the Institutional Review Board approved design are demonstrated under various possible true scenarios via simulation studies.